This manual explains the servo/spindle tuning so that the configured machine will be ready for the mechanical adjustment. Note that retuning is necessary when performing the following items: - Roundness measurement - Synchronous tapping adjustment - Adjustment for the shortest and optimum acceleration/deceleration - Actual machining test Refer to the following manuals. MDS-D/DH Series Instruction Manual (IB-1500025) MDS-D-SVJ3/SPJ3 Series Instruction Manual (IB-1500193) MS Configurator Instruction Manual (IB-1500154) CAUTION 1. Items related to servo tuning Keep the axis from collision when moving it. 2. Items related to spindle adjustment Do not adjust when possible risks associated with adjustment procedures are not thoroughly taken into consideration. Before tuning, ensure the safe operation at the maximum rotation speed. Be sure to break in the machine before tuning. Be careful when touching rotating section, or your hand may be caught in or cut. Changing of parameters has to be done carefully. CONTENTS 1 Introduction ..................................................................... 1 1.1 Aims of Servo/Spindle Tuning.................................................................................... 2 1.2 General Description of Servo Axis Control................................................................. 3 1.3 Speed loop gain ......................................................................................................... 4 1.4 Position loop gain....................................................................................................... 6 1.5 Relation of Speed Loop Gain and Position Loop Gain............................................... 8 1.6 Load inertia ................................................................................................................ 9 1.7 Resonance frequency ................................................................................................ 9 1.8 Acceleration/Deceleration Time Constant.................................................................. 9 1.9 General Description of Spindle Control.................................................................... 10 1.10 NC Screen.............................................................................................................. 11 1.10.1 Parameter Screen........................................................................................... 11 1.10.2 Drive Monitor Screen ...................................................................................... 12 1.11 MS Configurator ..................................................................................................... 13 2 Servo Tuning Procedure .............................................. 15 2.1 Flow of Servo Tuning ............................................................................................... 16 2.2 Setting Initial Parameters ......................................................................................... 17 2.2.1 Servo Parameters ............................................................................................. 17 2.2.2 Axis Specifications Parameters ........................................................................ 17 2.2.3 Machine Error Compensation Parameters........................................................ 18 2.3 Setting Resonance Frequencies .............................................................................. 19 2.4 Measuring Load Inertia Ratio ................................................................................... 22 2.5 Setting the Speed Loop Gain ................................................................................... 24 2.6 Setting the Position Loop Gain................................................................................. 28 2.7 Setting the Acceleration/Deceleration Time Constant.............................................. 30 2.8 Measuring Waveforms and Tuning .......................................................................... 32 2.8.1 Waveform Examples after Tuning..................................................................... 32 3 Spindle Tuning Procedure ........................................... 37 3.1 Flow of Spindle Tuning............................................................................................. 38 3.2 Setting Initial Parameters ......................................................................................... 39 3.3 Checking the Operation and Tuning ........................................................................ 40 3.3.1 Checking the Operation toward Maximum Rotation Speed .............................. 40 3.3.2 Setting the Acceleration/Deceleration Time Constant ...................................... 41 3.3.3 Tuning in Orientation......................................................................................... 43 3.4 Measuring Waveforms ............................................................................................. 44 3.4.1 Waveforms in Acceleration/Deceleration .......................................................... 44 3.4.2 Waveform in Orientation ................................................................................... 45 3.4.3 Others ............................................................................................................... 45 3.5 Waveform Examples and Tuning Methods .............................................................. 46 3.5.1 Waveforms in Acceleration/Deceleration .......................................................... 46 3.5.2 Waveform in Orientation ................................................................................... 52 1 Introduction 1 MITSUBISHI CNC 1 Introduction 1.1 Aims of Servo/Spindle Tuning Servo/spindle tuning aims at the following two points: (1) To achieve machine's high performance Servo/spindle parameter standard values allow a machine to successfully operate in spite of some inertia. However, conditions connected to the motor (inertia, machine's configuration and specifications (accuracy-oriented or efficiency-oriented), etc.) are not involved in the values. Therefore, the machinespecific optimum setting is required. (2) To find and solve problems Waveforms are not irrelevant to the machine's faults, unsatisfactory machining results or servo/spindle alarms. As the inertia increases, the current value will also increase. If machining surface is not good, the factors may be shown in the waveform (if not shown, mechanical factor will be assumed). If an alarm occurs, an abnormal waveform will be surely found. Thus, problems and countermeasures (retuning, replacing of machine parts or mechanical readjustment) will be clarified by measuring waveforms and tuning. Tuning is also used as a "life extension measure": if a machining failure occurs due to mechanical friction, the machine is basically not allowed to operate until the parts are replaced. However, tuning under the current state allows the machine to be used in the meanwhile. 2 Servo/Spindle Tuning Guide 1.2 General Description of Servo Axis Control 1.2 General Description of Servo Axis Control Servo axis control is to keep the axis at the cyclically-commanded position (at every communication cycle between NC and servo amplifier) and at the commanded feedrate (rotation speed). During axis stop Control No rotation. Keep the commanded position! Machine Table Disturbance (pushing force) Tension (returning force) Tension is produced to keep the commanded position. During axis movement Control Follow the commanded position and rotation speed! Machine Disturbance (pushing force) Table Tension (returning force) As the command will not change in spite of dropping rotation speed, tension is produced to regain the commanded rotation speed and position. In the example above, the tension against the disturbance (the force to regain the speed and position by passing a current through the motor) is controlled by speed loop gain and position loop gain. 3 MITSUBISHI CNC 1 Introduction 1.3 Speed loop gain Speed loop gain is the response speed to regain the commanded speed when the motor speed deviates due to cutting load and the like. Comparison at the speed deviation When speed loop gain is increased When the speed loop gain is decreased Responsiveness Command speed will be quickly regained. Machining will be less affected by speed deviation factors (load change. etc), producing smoother rotation. Command speed will be slowly regained. Machining will be easily affected by speed deviation factors (load change. etc), producing rougher rotation. Machining result Machining result will be like the one when the torque (power) has been increased. (Ex: The machining surface is improved.) Machining result will be like when the torque (power) has been decreased. (Ex: The machining surface gets worse.) Setting the higher speed loop gain is a key of servo tuning. Will the highest speed loop gain lead the best machining? If the speed loop gain is too high or too low, the following cases will occur. (a) When too good responsiveness (too high gain) is set for the machine with small weight and friction which regains the commanded speed with a small force: The regained speed will exceed the commanded speed. If the responsiveness against the excessive speed is too sharp, oscillation will eventually occur. -> Vibrations with high frequency will occur. The speed deviation will be rather larger. Continuous vibration with high frequency is called "oscillation". The higher the speed loop gain is, the more the oscillation is likely to occur; the lower, the less. (Waveform example) Speed feedback - Position droop waveform Narrow vibrations are distributed on the whole. 4 Servo/Spindle Tuning Guide 1.3 Speed loop gain (b) When too little responsiveness (too low gain) is set for the machine with large weight and friction which requires a large force to regain the commanded speed: The response to regain the commanded speed will be slow. -> Vibrations with low frequency will occur. The speed deviation will not be reduced (the commanded speed will be hardly regained). Constant unstable waveform with low frequency is called "fluctuation". (Waveform example) Speed feedback - Position droop waveform 5 or 6 waves have occurred in 1 or 2 second(s). Set the appropriate speed loop gain corresponding to the inertia ratio (weight ratio) to the motor. 5 MITSUBISHI CNC 1 Introduction 1.4 Position loop gain Position loop gain is the responsiveness in time; how quickly the motor reaches the commanded position (spped) when a different command is issued. Comparison when a different rotation speed is commanded Responsiveness Position (speed) will be quickly changed. When position loop gain is Response to the rotation change will be increased faster. Position (speed) will be slowly changed. When the position loop Response to the rotation change will be gain is decreased slower. Machining result Machining result will be like when the time constant has been shorten. (Ex: The shape (size, etc) is accurate.) Machining result will be like when the time constant has got longer. (Ex: The shape (size, etc) is inaccurate.) Setting the higher position loop gain is also a key of servo tuning. Will the highest position loop gain lead the best machining? If the position loop gain is too high or too low, the following cases will occur. (a) When too good responsiveness (too high gain) is set for the machine with small rigidity (loader and the like, whose weight balance is not good) -> The machine vibrates at the change of the command speed, or overshoot occurs at acceleration/deceleration. "Overshoot" means that the machine's position exceeds the commanded position at a speed change (acceleration -> constant speed or deceleration -> stop). (Waveform example) Speed feedback - Position droop waveform Overshoots happen at the circled points. 6 Servo/Spindle Tuning Guide 1.4 Position loop gain (b) When too little responsiveness (too high gain) is set for the machine with rigidity (machine whose weight balance is good, or light and small machine) -> The machine will work slowly. The machining accuracy will deteriorate. (Waveform example) Position command - Position feedback waveform (A) When position loop gain is appropriate (B) When position loop gain is low Set the appropriate position loop gain corresponding to the machine's configuration and the inertia ratio. 7 MITSUBISHI CNC 1 Introduction 1.5 Relation of Speed Loop Gain and Position Loop Gain As explained so far, speed loop gain is the responsiveness to the speed deviation, and position loop gain is the responsiveness to the command speed change. If an overshoot occurs after increasing the position loop gain, the overshoot can be eliminated by increasing the speed loop gain, because the overshoot is related to the speed deviation. In reverse, if an overshoot occurs at acceleration/deceleration, the overshoot can be eliminated by decreasing the position loop gain and applying slow accelecation/deceleration, because the acceleration/ deceleration means a change of command speed. Which is set first? Considering the following features, set the speed loop gain first, then set the position loop gain. Speed loop gain Standard speed loop gain is determined by measuring the inertia ratio. Axis-specific setting is available (because each axis has a different inertia ratio.) Upper limit is determined by the inertia ratio. Setting over the upper limit is impossible. Position loop gain Determined by the mechanical structure, as well as the inertia ratio. Whether the value is high or low is only judged by moving the axis. Adjustment among interpolation axes is required. For interporation axes, upper limit is determined by the speed loop gain. Set the speed loop gain first. Then set the position loop gain considering the determined speed loop gain and the mechanical structure. 8 Servo/Spindle Tuning Guide 1.6 Load inertia 1.6 Load inertia Inertia is physical quantity to express load amount. In servo control, load inertia (diameter, friction, etc.), which is converted into motor axis, is more important than load weight. Servo response is in proportion to speed loop gain and in inverse proportion to load inertia. It is essential to know the load inertia amount when determining appropriate speed loop gain. Load inertia In servo tuning, measure the load inertia first. Then determine the standard speed loop gain accoriding to the inertia. 1.7 Resonance frequency "Resonance" is a large vibration when machine and motor's own vibration frequencies affect each other. All machines have a resonance point and the resonance of ball screw is a serious problem. Resonance has to be suppressed as it prevents the speed loop gain from being raised. Notch filter is installed on servo and it suppresses the resonance. However, resonance frequency has to be set for each machine to set parameters. Vibration waveform Recognizing resonance frequency and suppressing resonance for raising the speed loop gain is a key in servo tuning. 1.8 Acceleration/Deceleration Time Constant Shorter and smoother acceleration/deceleration is also important. When the position loop gain is adjusted, acceleration/deceleration time constant should also be adjusted, because the position loop gain is related to the time to complete positioning. Set the time constant with parameters. The values should be set so that the maximum current at acceleration/deceleration will not exceed the maximum current command value. Set the acceleration/deceleration time constant so that the current value will not exceed the maximum current command value. 9 MITSUBISHI CNC 1 Introduction 1.9 General Description of Spindle Control Spindle control is largely divided into two types. Control 1: Always follows the commanded rotation speed with the maximum power of spindle amplifier and motor -> Only the responsiveness to the commanded speed is provided, which is mainly controlled by speed loop gain. Spindle always follows the maximum power; the position and acceleration/deceleration time constant need not to be considered. The catch-up time difference is due to the power of spindle amplifier and motor, as well as the inertia (weight, friction and centrigugal force) of an object to rotate. It is like when a man who carries a burden runs 100m at full speed. Power of spindle amplifier and motor = The man's ability A burden = machine's inertia To run faster (to shorten the acceleration/deceleration time), raising the ability (increasing the power of spindle amplifier and motor) and reducing the burden (decreasing the inertia) are required. As reducing the burden (inertia) is hardly possible, raising the ability (increasing the power) should be considered. The adjustment of spindle's speed loop gain is the same as that of servo axis. Control 2: Like servo axis, follows the commanded position -> Controlled by speed loop gain and position loop gain. In the following operations, spindle is controlled similarly as servo axis. (a)Orientation (Stop at fixed position) (b)Spindle/ C axis control (c)Synchronous tap control (d)Spindle synchronization Spindle must stop at a fixed position, which requires the control according to the commanded position. Spindle is controlled like a servo C axis (rotation axis), which requires the position control all the time including acceleration/ decelertion. Spindle and servo axis (Z axis) are simultaneously controlled. (When the pitch 1mm is commanded, spindle is controlled to rotate once per 1mm of Z axis movement. Position control is required all the time including acceleration/decleration. Spindles (or spindle and servo axis) are controlled to be at the commanded speed and postition all the time including acceleration/deceleration. These operations require the time constant setting according to the inertia. 10 Servo/Spindle Tuning Guide 1.10 NC Screen 1.10 NC Screen The following screens are mainly used in servo/spindle tuning. 1.10.1 Parameter Screen Parameters are displayed and set. How to display the parameter screen and set a value (1) Press key to display the Mainte screen. (2) Select [Mainte] and then [Psswd input] menus. (3) Enter "MPARA" in the setting area and press the INPUT key. (4) Select [Param] menu. (5) Select [Param number] menu. Enter the parameter No. in the setting area and press the INPUT key. The cursor moves to the entered parameter position. (6) Enter a value and press the INPUT key. The menus on the parameter screen ([Servo param], [Spindle spec param] and [Spindle param]) are also available for the parameter display. 11 MITSUBISHI CNC 1 Introduction 1.10.2 Drive Monitor Screen The diagnosis information from the drive section can be monitored with this screen. How to display the drive monitor screen (1) Press key to display the Diagn screen. (2) Select [Drv mon] menu. (3) Select [Servo unit] to display the servo monitor screen. Select [Spindle unit] to display the spindle monitor screen. 12 Servo/Spindle Tuning Guide 1.11 MS Configurator 1.11 MS Configurator With MS Configurator, the servo parameters can be automatically adjusted by activating the motor with test NC programs or vibration signals, and analyzing the machine characteristics. Data measurement function is also provided. Cable H200 In this manual, MS Configurator is used in servo tuning to sample waveforms. 13 2 Servo Tuning Procedure 15 MITSUBISHI CNC 2 Servo Tuning Procedure 2.1 Flow of Servo Tuning Start Setting Initial Parameters Refer to 2.2 Setting Resonance Frequencies Refer to 2.3 Set the resonance frequency of filter to suppress resonance. Measuring the Load Inertia Ratio Refer to 2.4 Perform an axis reciprocation with G00 (Rapid traverse) at full stroke to measure the load inertia ratio. Setting the Speed Loop Gain Refer to 2.5 Set the speed loop gain according to the measured load inertia ratio. Then check for any unusual noise or vibration. Setting the Position Loop Gain Refer to 2.6 Set the parameters for position loop gain. Then check for any mechanical vibration. Setting the Acceleration/Deceleration Refer to 2.7 Adjust the acceleration/deceleration time constants at G00 and G01 so that the current does not exceed the maximum current command value. Refer to 2.8 Execute G01 (cutting feed) and then G00 (rapid traverse), measuring waveforms and tuning. Time Constant Measuring Waveforms and Tuning End 16 Servo/Spindle Tuning Guide 2.2 Setting Initial Parameters 2.2 Setting Initial Parameters 2.2.1 Servo Parameters (1) Set standard values in the servo parameters on the axes for tuning. Refer to "List of standard parameters for each servomotor" of the servo drive unit's Instruction Manual. (2) Set all the following compensation/filter/ resonance frequency parameters to "0 (Disabled)". No. Parameter name Setting #2227 SV027 (SSF1) Servo function selection 1 Set "4000" #2233 SV033 (SSF2) Servo function selection 2 Set "0000" #2238 SV038 (FHz1) Notch filter frequency 1 Set "0" #2246 SV046 (FHz2) Notch filter frequency 2 Set "0" #2283 SV083 (SSF6) Servo function selection 6 Set "0" #2287 SV087 (FHz4) Notch filter frequency 4 Set "0" #2288 SV088 (FHz5) Notch filter frequency 5 Set "0" (3) Enable the speed feedback filter to eliminate high-frequency vibration noise. No. #2217 Parameter name SV017 (SPEC1) Servo specification selection 1 Setting Change "00*0" to "00*8" 2.2.2 Axis Specifications Parameters (1) Temporarily disable the backlash compensation. Take a note of the axis' original set values in "#2011" and "#2012". Then set both to "0". No. Parameter name Setting #2011 G0back G0 backlash Set "0" #2012 G1back G1 backlash Set "0" Be sure to take a note and set the original values back after tuning. (2) Enable the feed forward gain. Set "#2139" to "1" to apply the conventional feed forward control. No. #2139 Parameter name omrff_off Setting Set "1: Temporarily disable". OMR-FF invalid 17 MITSUBISHI CNC 2 Servo Tuning Procedure 2.2.3 Machine Error Compensation Parameters Temporarily disable the machine error compensation. Take a note of the axis' original set value of "#4006 (, #4016, #4026...)". Then set it to "0". No. #4006 (#4016, 4026...) Parameter name sc Compensation scale factor Setting Set "0" Be sure to take a note and set the original values back after tuning. 18 Servo/Spindle Tuning Guide 2.3 Setting Resonance Frequencies 2.3 Setting Resonance Frequencies Parameters to set No. Parameter name Setting #2205 SV005 (VGN1) Speed loop gain 1 Set a speed loop gain #2238 SV038 (FHz1) Notch filter frequency 1 Set a resonance frequency #2246 SV046 (FHz2) Notch filter frequency 2 Set a resonance frequency (When SV038 has already been set) #2233 SV033 (SSF2) Servo function selection 2 Set the depth of notch filter 2 * Set for each axis. Set the resonance frequency of filter to suppress resonance. Attach the cover to the table and take the workpiece off before setting. Keep the axis from collision when moving it. (1) Display the servo monitor screen. (2) Move the axis by handle/JOG feed. Check for any unusual noise or vibration. If unusual noise or vibration occurs: (1) See the resonance frequency on the servo monitor screen. ("AFLT frequency") 19 MITSUBISHI CNC 2 Servo Tuning Procedure (2) Display the parameter screen. Set the resonance frequency in "#2238 SV038". (3) Display the parameter screen. Set "(speed loop gain standard parameter value) + 50" in "#2205 SV005". For the standard parameter value, refer to "List of standard parameters for each servomotor" of the drive unit's Instruction Manual. 20 Servo/Spindle Tuning Guide 2.3 Setting Resonance Frequencies (4) Move the axis by handle/JOG feed again. Check for any unusual noise or vibration. If no noise or vibration occurs: Set the standard parameter value in SV005. If any noise or vibration occurs: (1) See the resonance frequency on the servo monitor screen. ("AFLT frequency") (2) Display the parameter screen. Set the frequency in "#2238 SV038" (or "#2246 SV046" when "#2238" has already been set). (3) Move the axis again. If no noise or vibration occurs, set the standard parameter value in SV005. Before setting SV046, set "#2233 SV033" to "**8*". If the displayed frequency is almost the same as SV038 frequency (within ±30Hz): Set "#2233 SV033" smaller as follows; "***0"(- ∞ ) -> "***2"(-18.1db) -> "***4" (-12.0db) -> "***6" (-8.5db)... Confirm the resonance frequency ("AFLT frequency") shows "0" or different value from SV038 on the servo monitor screen. If the resonance frequency is unstable ("AFLT frequency" shows more than ±10 deviation): Lower the SV005 value until the frequency is stabilized. If the resonance frequency still exists after both SV038 and SV046 settings: Lower the SV005 value until the frequency shows "0". If the frequency is over 900Hz (a keening noise is heard), the amount may not be displayed. In such a case, set "1125", "2250" or "900" in SV038 (or SV046). (5) Move the axis by rapid traverse with override 100%. Check for any unusual noise or vibration. If any problem occurs, take the same measures as (4). 21 MITSUBISHI CNC 2 Servo Tuning Procedure 2.4 Measuring Load Inertia Ratio Parameters to set No. Parameter name #2232 SV032 (TOF) #2004 #2005 #2235 #2237 Setting Torque offset 1 Set the unbalance torque of vertical axis G0tL G0 time constant (linear) G0t1 G0 time constant (primary delay) Set a time constant for rapid traverse acceleration/deceleration SV035 (SSF4) Servo function selection 4 SV037 (JL) Load inertia scale Set "1" in bitF. "0000" is changed to "8000". Set a load inertia * Set for each axis. Perform an axis reciprocation with G00 (Rapid traverse) at full stroke to measure the load inertia ratio. (1) Set an unbalance torque in "#2232 SV032" on vertical axis when used. Move the axis at about F1000 and measure the load current on the servo monitor screen. Then apply the following formula. Unbalance torque = {(+ Feed load current (%)) + (- Feed load current (%))} / 2 (2) Prepare an MDI/memory operation of rapid traverse with override 100%. (Ex.) G00 feed for reciprocation of 200mm with onesecond dwell time *Apply the maximum travel amount for a short stroke less than 200mm. Always use MDI or memory operation. JOG or Rapid feed does not provide an average inertia value in a constant cycle. (3) Carry out a test run with the program prepared in (2). During the test run, see the maximum current value shown in "Max current 2 (or 3)" on the servo monitor screen. 22 Servo/Spindle Tuning Guide 2.4 Measuring Load Inertia Ratio (4) Set the time constant so that the maximum current value stays between 150 and 200 (%). Adjust the "#2004/#2005" value until "Max current 2 (3)" shows "150 to 200" at acceleration/deceleration. (5) Stop the run and set the display of load inertia ratio on the servo monitor screen. Display the parameter screen. Set "1" in "#2235 SV035/bitF". ("0000" is changed to "8000".) Complete the step (4) before (5). Slowly raising the feedrate after (5) will add extra 15 to 30 minutes to stabilize the inertia display. (6) Set the feedrate to 100% and run the (2) program for about 15 minutes. During the run, see the load inertia ratio on the servo monitor screen. Run the program until the load inertia ratio is stabilized "with 1% or less deviation in five reciprocations". (7) Take a note of the load inertia ratio stabilized in (6). Then stop the run. (8) Display the parameter screen. Set the noted inertia ratio in "#2237 SV037". (9) Cancel the load inertia ratio display. Set "1" in "#2235 SV035/bitF". ("*000" is changed to "0000".) 23 MITSUBISHI CNC 2 Servo Tuning Procedure 2.5 Setting the Speed Loop Gain Parameters to set No. Parameter name #2205 SV005 (VGN1) Setting Speed loop gain 1 Set a speed loop gain #2238 SV038 (FHz1) Notch filter frequency 1 Set a resonance frequency #2246 SV046 (FHz2) Notch filter frequency 2 Set a resonance frequency (When SV038 has already been set) * Set for each axis. Set the speed loop gain according to the measured load inertia ratio. Then check for any unusual noise or vibration. If any vibration occurs, set a resonance frequency again. Attach the cover to the table and take the workpiece off before setting. Keep the axis from collision when moving it. (1) Determine the speed loop gain according to the load inertia ratio in "#2237 SV037". Refer to "Standard VGN1 graph" below and set the motor-specific speed loop gain. (2) Set "(determined value in (1)) + 50" in "#2205 SV005". (3) Execute the handle, JOG and then Rapid operation. If no noise or vibration occurs: Set the determined value in (1) in "#2205 SV005". If any noise or vibration occurs: (1) See the resonance frequency on the servo monitor screen. ("AFLT frequency") (2) Display the parameter screen. Set the frequency in "#2238 SV038" (or "#2246 SV046" when "#2238" has already been set). (3) Move the axis again. If no noise or vibration occurs, set the determined value in (1) in SV005. Refer to the chapter of "Setting Resonance Frequencies" written before. 24 Servo/Spindle Tuning Guide 2.5 Setting the Speed Loop Gain Reference MDS-D/DH Series Standard VGN1 graph (servo motor HF, HF-H Series) [ HF75, HF54 [ HF-H75, HF-H54 ] ] [ HF105, HF104, HF154 [ HF-H105, HF-H104, HF-H154 Isolated motor Standard VGN1 Isolated motor 600 600 500 500 400 400 300 300 200 200 100 100 0 100 200 300 400 500 600 0 100 [ HF204, HF354 [ HF-H204, HF-H354 ] ] Isolated motor 400 500 600 ] ] Isolated motor 600 500 500 400 400 300 300 200 200 When OSA166 used When OSA 105 used 100 200 300 [ HF453, HF703 [ HF-H453, HF-H703 600 0 100 200 Load inertia magnification (%) Load inertia magnification (%) Standard VGN1 ] ] 300 400 500 When OSA166 used When OSA105 used 100 600 0 100 200 300 400 500 Load inertia magnification (%) Load inertia magnification (%) 25 600 MITSUBISHI CNC 2 Servo Tuning Procedure MDS-D/DH Series Standard VGN1 graph (servo motor HP, HP-H Series) [ HP54, HP154, HP224 [ HP-H54, HP-H154, HP-H224 ] ] [ HP104 [ HP-H104 Isolated motor Standard VGN1 Isolated motor 600 600 500 500 400 400 300 300 200 200 100 100 0 100 200 300 400 500 600 0 100 Load inertia magnification (%) [ HP204, HP354, HP454 [ HP-H204, HP-H354, HP-H454 ] ] 400 500 600 ] ] Isolated motor 600 500 500 400 400 300 300 200 200 When OSA166 used When OSA105 used 100 200 300 [ HP704, HP903, HP1103 [ HP-H704, HP-H903, HP-H1103 600 0 100 200 Load inertia magnification (%) Isolated motor Standard VGN1 ] ] 300 400 500 When OSA166 used When OSA105 used 100 600 0 100 200 300 400 500 Load inertia magnification (%) Load inertia magnification (%) 26 600 Servo/Spindle Tuning Guide 2.5 Setting the Speed Loop Gain MDS-D-SVJ3 Series Standard VGN1 graph (servo motor HP, HP-H Series) [ HF75, HF54 ] [ HF105, HF104, HF154 Isolated motor Standard VGN1 Isolated motor 600 600 500 500 400 400 300 300 200 200 100 100 0 100 200 300 400 500 600 [ HF204, HF354 ] Isolated motor 600 500 400 300 200 When OSA166 used When OSA 105 used 100 0 100 200 300 400 500 0 100 200 300 400 500 Load inertia magnification (%) Load inertia magnification (%) Standard VGN1 ] 600 Load inertia magnification (%) 27 600 MITSUBISHI CNC 2 Servo Tuning Procedure 2.6 Setting the Position Loop Gain Parameters to set No. Parameter name Setting ratio #2203 SV003 (PGN1) Position loop gain 1 #2204 SV004 (PGN2) Position loop gain 2 #2257 SV057 (SHGC) SHG control gain #2208 SV008 (VIA) Speed loop lead compenSet "1900", the standard value, in SHG control sation 700 to 2500 #2215 SV015 (FFC) Acceleration rate feed forSet "100", the standard value, in SHG control ward gain 0 to 300 #1194 H_acdc Time constant 0 for handle feed 1 Standard setting range Setting example 8 3 6 18 21 23 26 33 38 47 18 to 70 48 56 61 70 88 101 125 48 to 186 108 126 138 156 198 228 282 108 to 420 Set "0" when using time constant for G01 in manual handle feed mode * Set for each axis. Interpolation axes (synchronously controlled) must have the same lowest value. Set the parameters for position loop gain. Then check for any mechanical vibration. SHG control changes the position loop to a high-gain by smoothly compensating the servo system position loop through a delay. This allows the settling time to be reduced and a high precision to be achieved. (SHG: Smooth High-Gain) This manual explains the setting with SHG control. Use the setting example above for the SHG control parameters (SV003, SV004 and SV057). When the axis is synchronized with spindle (in synchronous tap or spindle/C axis control), the spindle will have automatically-calculated values (SV003 : SV004 : SV057 = 1: 8/3 :6). Set the calculated values (rounded to the nearest integer) for the servo axis accordingly. (1) Set the following parameters using "SV003=33" settings. SV003 (PGN1): "33" SV004 (PGN2): "88" SV008 (VIA): "1900" SV015 (FFC): "100" SV057 (SHGC): "198" "SV003=33" settings are normally used. "SV003=26" settings are used for the system with scale specifications, rotary axis, gear or belt drive, which is more vibratable than semi-closed one. "SV003=9" settings can be used for the system with longer machine end such as loader axis or especially arm axis. 28 Servo/Spindle Tuning Guide 2.6 Setting the Position Loop Gain (2) Execute the handle, JOG and then Rapid operation. Check for any mechanical vibration at acceleration/deceleration. When any vibration occurs at acceleration/ deceleration: Decrease SV003, SV004 and SV057 values, keeping the ratio 1 : 8/3 : 6, until the vibration disappears. Setting the longer time constant will also eliminate the vibration. However, if the vibration still exists while the maximum current value at the acceleration/deceleration is down to 50% or less, time constant does not help suppress the vibration. Then set the lower SHG control gain. When the vibration occurs only in the handle feed: Set "0" in "#1194 H_acdc (Time constant 0 for handle feed)". Then set the longer time constant for G01. For the G01 time constant setting, use "#2007" or "#2008" according to the acceleration/ deceleration mode. (3) When using multiple axes, carry out these adjustments for each axis. Interpolation axes must have the same position loop gain value. Set the same lowest value for all the interpolation axes. 29 MITSUBISHI CNC 2 Servo Tuning Procedure 2.7 Setting the Acceleration/Deceleration Time Constant Parameters to set No. Parameter name Setting #2001 rapid Rapid traverse rate Set the rapid traverse feedrate for each axis #2002 clamp Cutting feedrate for clamp function Set the maximum cutting feedrate for each axis #2004 G0tL G0 time constant (linear) #2005 G0t1 G0 time constant (primary delay) #2007 G1tL G1 time constant (linear) #2008 G1t1 G1 time constant (primary delay) Set a time constant for rapid traverse acceleration/deceleration Set a time constant for cutting acceleration/ deceleration * Set for each axis. When setting "#2007" or "#2008" for multiple axes, set the same lowest value for all the axes. Adjust the acceleration/deceleration time constants at rapid traverse (G00) and cutting feed (G01) so that the current does not exceed the maximum current command value ("max."). (1) Display the parameter screen. Set a rapid traverse rate (G00) in "#2001", a cutting feedrate (G01) in "#2002". (2) Display the servo monitor screen. (3) Move the axis in MDI or memory mode at the rapid traverse rate (G00) and the maximum cutting feedrate (G01). (4) See "Max current 2 (or 3)" on the servo monitor screen. Confirm that the current peak value at the acceleration/deceleration does not exceed the "max." (or 70% of the "max." in cutting feed). "Max current 1" shows the current peak value after the power ON. "Max current 2 (or 3)" shows the instantaneous peak value of load current. 30 Servo/Spindle Tuning Guide 2.7 Setting the Acceleration/Deceleration Time Constant For the maximum current command value ("max."), refer to the chart below. When the current exceeds the "max.": Set the longer time constant. When the current is below the "max.": Shortening the time constant is allowed. When the current is below the "max.", vibration occurred by shortening the time constant: Adjust the time constant so that the vibration does not occur. Set the time constant in any of the parameters "#2004" to "#2008". (5) When using multiple axes, carry out these adjustments for each axis. G01 time constant ("#2007" or "#2008") must be the same among all the axes. Set the same lowest value for all the axes. Reference: Maximum current command value when adjusting acceleration/deceleration time constant Motor model HF75 HF105 HF54 HF104 HF154 HF204 HF354 HF453 HF703 HF903 MDS-D Series (200V) Max. current Motor command model value Within 350% HP54 Within 270% HP104 Within 420% HP154 Within 504% HP204 Within 378% HP354 Within 340% HP454 Within 331% HP704 Within 298% HP903 Within 238% HP1103 Within 291% Max. current command value Within 306% Within 262% Within 434% Within 312% Within 320% Within 311% Within 216% Within 215% Within 184% Motor model HF-H75 HF-H105 HF-H54 HF-H104 HF-H154 HF-H204 HF-H354 HF-H453 HF-H703 HF-H903 MDS-DH Series (400V) Max. current Motor command model value Within 350% HP-H54 Within 270% HP-H104 Within 420% HP-H154 Within 504% HP-H204 Within 378% HP-H354 Within 312% HP-H454 Within 331% HP-H704 Within 298% HP-H903 Within 238% HP-H1103 Within 291% MDS-D-SVJ3 Series (200V) Max. current Motor model command value HF75 437 HF105 337 HF54 525 HF104 439 HF154 472 HF204 356 HF354 290 31 Max. current command value Within 306% Within 262% Within 434% Within 312% Within 320% Within 311% Within 216% Within 215% Within 184% MITSUBISHI CNC 2 Servo Tuning Procedure 2.8 Measuring Waveforms and Tuning Execute G01 (cutting feed) and then G00 (rapid traverse), measuring waveforms and tuning. In each mode, sample the waveforms in the following order: (1) Speed feedback- Position droop waveform (deviation between the command and the position feedback) (2) Speed feedback - Current feedback waveform Tuning is for achieving good machining results. In order to achieve good machining results, it is essential to keep the stable droop or the waveform without overshoot or fluctuation, especially in G01 (cutting feed). After realizing the stability, try shortening the time constant (or tact time) and improving the responsibility (or accuracy). Thus, a position droop waveform should be firstly sampled to confirm that the servo motor’s rotation is stable. For the waveform measurement, refer to "MS Configurator Instruction Manual" (IB-1500154). 2.8.1 Waveform Examples after Tuning The following shows the waveforms measured by MS Configurator. These are the examples in G01 (cutting feed). The result will be the same in G00 (rapid traverse). As for G00, however, the allowable fluctuation is 5μm. In other mode, the allowance is should be 1μm (3μm during the axis travel) Check the points in both forward and backward travels. Speed feedback - Position droop waveform Point 3 Point 1 Point 2 32 Servo/Spindle Tuning Guide 2.8 Measuring Waveforms and Tuning Point 1: At acceleration -> constant speed: Make sure there is no overshoot or delay in feed (more than 3μm). "Delay in feed" is a waveform where the feed seems to stop once and move again. Tuning method (1) Set the longer time constant. (2) If the peak current value shows 50% or less, set the lower position loop gain (SV003, SV004 and SV057). After confirming the stable waveform, shorten the time constant. Point 2: At constant speed: Make sure there is no fluctuation (over 3μm) except cyclic vibration. Tuning method Set the higher speed loop gain (SV005). If any cyclic vibration is found, sample a waveform at a different feedrate. If the vibration cycle changes depending on the feedrate, mechanical factor (such as core deflection) may be affecting the vibration. Point 3: At deceleration -> stop: Make sure there is no overshoot or delay in feed (more than 1μm). Tuning method (1) Set the longer time constant. (2) If the peak current value shows 50% or less, set the lower position loop gain (SV003, SV004 and SV057). After confirming the stable waveform, shorten the time constant. 33 MITSUBISHI CNC 2 Servo Tuning Procedure Speed feedback - Current feedback waveform Point 4 Point 5 34 Servo/Spindle Tuning Guide 2.8 Measuring Waveforms and Tuning Point 4: Make sure there is no current value exceeding the "max." For the "max." value, refer to the chart in the chapter 2.7. Tuning method (1) Set the longer time constant. (2) If the peak current value shows 50% or less, set the lower position loop gain (SV003, SV004 and SV057). After confirming the stable waveform, shorten the time constant. Point 5: At constant speed: Make sure there is no fluctuation (more than 3μm). Tuning method Set the higher speed loop gain (SV005). If any cyclic vibration is found, sample a waveform at a different feedrate. If the vibration cycle changes depending on the feedrate, mechanical factors (such as core deflection) may be affecting the vibration. Check for any change (up and down) of current value as well during the axis travel. Especially on horizontal axis, the load current change may be caused by mechanical factors (such as guides’ crossing angle). 35 3 Spindle Tuning Procedure 37 MITSUBISHI CNC 3 Spindle Tuning Procedure 3.1 Flow of Spindle Tuning Keys of spindle tuning (1) Always check the waveform while tuning. (Note) At a point of May, 2008, MS Configurator’s spindle waveform measure functions don’t support all the models or all kinds of data. For exact spindle tuning, waveforms should be sampled from spindle amplifier's D/A output, using a measure device such as a waveform recorder. When using such a device, set the time axis range to either 20ms/DIV or 50ms/DIV. With the range 100ms/DIV or more, the device will not sample an accurate waveform. (2) Tune the spindle at every rotation speed, not only at the maximum. As rotation speed changes, torque (power) will also change. (3) Repeat accelerations/decelerations when sampling waveforms. As temperature changes, friction may also change due to heat expansion, etc. (4) Always mount the chuck before tuning. Results may differ due to the chuck weight. CAUTION 1. 2. 3. 4. 5. Do not adjust when possible risks associated with adjustment procedures are not thoroughly taken into consideration. Before tuning, ensure the safe operation at the maximum rotation speed. Be sure to break in the machine before tuning. Be careful when touching rotating section, or your hand may be caught in or cut. Changing of parameters has to be done carefully. Start Setting Initial Parameters Refer to 3.2 Checking the Operation and Tuning Refer to 3.3 Checking the Operation Tuning in Orientation Setting the Acceleration/ Deceleration Time Constant (Tuning in other operations) Rotate the spindle up to the maximum rotation speed. Check for any fluctuation in rotation or vibration in the waveform. Repeat accelerations/decelerations. Sample waveforms both in room temperature and in high temperature for tuning. Take this tuning method when using orientation. Execute orientations from the maximum rotation speed, every rotation speed and from 180 degrees position. Sample waveforms and tune the spindle in each orientation. Tune the spindle in the other operation such as spindle/C axis control. End 38 Servo/Spindle Tuning Guide 3.2 Setting Initial Parameters 3.2 Setting Initial Parameters (1) Set the following parameters: "#3001 slimit1" to "#3137 stap_ax_off" according to the machine's specifications; "#13001 SP001" to "#13256 SP256" according to the "Parameter setting list" from MITSUBISHI. (2) Set the following filter-setting parameters to "0". No. Parameter name Setting #13038 SP038 (FHz1) Notch filter frequency 1 Set "0" #13046 SP046 (FHz2) Notch filter frequency 2 Set "0" #13087 SP087 (FHz4) Notch filter frequency 4 Set "0" #13088 SP088 (FHz5) Notch filter frequency 5 Set "0" Follow the parameter setting list. As long as the spindle inertia is within 3-fold (in almost all machining centers), the operation will have no problem with standard values from the list. If the inertia exceeds 3-fold (in lathe system with chuck, etc.), set "#13005 SP005" to "200" instead of "150". 39 MITSUBISHI CNC 3 Spindle Tuning Procedure 3.3 Checking the Operation and Tuning Parameters to set No. Parameter name #13001 SP001 (PGV) #13005 SP005 (VGN1) Setting Position loop gain Non-interpolation mode Start with "15" ("5" in lathe system) Speed loop gain 1 Change the value when a problem occurs even if SP001 is lowered to "5" 3.3.1 Checking the Operation toward Maximum Rotation Speed Rotate the axis with gradually raising the rotation speed toward the maximum. Check for any rough rotation or fluctuation in the waveform. Before tuning, ensure the safe operation at the maximum rotation speed. At the first rotation command since the power ON, the rotation speed is raised up to the "#3109 zdetspd (Z phase detection speed)" speed. The speed will be raised up to the commanded speed after Z phase detection. If the rotation speed has not been raised for a long time, check the PLG. (1) Display the parameter screen and set "15" ("5" in lathe system) in "#13001 SP001". (2) Rotate the spindle with gradually raising the rotation speed (1000 to 2000 r/min at a time). Check for any fluctuation in the following waveforms at every rotation speed. (a) Speed - Phase current waveform (b) Speed - Current feedback waveform (Ex.) Run the following program with executing single blocks. S1000 M3; S2000; S3000; : S**; (**: Max. rotation speed (Smax value)) M5 Watch the waveform in the recorder during the run. Check only the constant speed rotation waveform. When any fluctuation occurs during constant speed rotation: (1) Stop the operation and raise the speed loop gain (SP005). (2) Restart the operation with the speed at which the fluctuation occurred. Check the waveform. (3) If the fluctuation still exists, lower the speed loop gain. 40 Servo/Spindle Tuning Guide 3.3 Checking the Operation and Tuning 3.3.2 Setting the Acceleration/Deceleration Time Constant Repeat accelerations/decelerations. Sample waveforms both in room temperature and in high temperature for tuning. (1) Display the spindle monitor screen. Wait until the spindle temperature goes down to the room temperature. Spindle temperature is shown in "Temperature". (2) Sample waveforms in acceleration/ deceleration at room temperature. Execute "stop --> maximum rotation speed" for sampling them. (Ex.) Run the following program with executing single blocks. S8000 M3; M5 Dwell time setting is also available if the speedstabilized time is confirmed. For how to sample waveforms, refer to the later chapter of "Measuring Waveforms". (3) Repeat accelerations/decelerations until the temperature on the spindle monitor screen reaches around 80 C°. (4) Sample waveforms in acceleration/ deceleration at 80 C°. Execute "stop --> maximum rotation speed" for sampling them. For how to sample waveforms, refer to the later chapter of "Measuring Waveforms". 41 MITSUBISHI CNC 3 Spindle Tuning Procedure (5) Compare the waveforms between (2) and (4). Apply the temperature at which the waveform shows worse. Tune the spindle in acceleration/deceleration toward/from the maximum rotation speed. When both waveforms are similarly not good: (1) Start tuning at the temperature with shorter deceleration time. (2) Then, tune at the other temperature. When both waveforms are good: Choose the temperature with shorter deceleration time for tuning. For checking waveforms and tuning, refer to the later chapter of "Waveform Examples and Tuning Methods". (6) Decrease the rotation speed (1000 to 2000 r/ min at a time). Tune the spindle at every rotation speed. Execute "stop --> rotation speed" and sample waveforms for tuning at every rotation speed. For checking waveforms and tuning, refer to the later chapter of "Waveform Examples and Tuning Methods". (7) After completing tunings at every rotation speed, raise the position loop gain. Set "33" ("15" in lathe system) in "#13001 SP001". (8) Execute accelerations/decelerations, sample waveforms and tune the spindle at every rotation speed toward the maximum. Start with the lowest rotation speed. Then gradually raise the speed. When an overshoot occurs: Lower the position loop gain (SP001) until no overshoot is found. When an overshot occurs even if SP001 is lowered to "5": (1) Set "200" and "100" in "#13005 SP005". Sample each two sets of waveforms. (2) Compare the waveforms. Choose the SP005 value with less problem. 42 Servo/Spindle Tuning Guide 3.3 Checking the Operation and Tuning 3.3.3 Tuning in Orientation Parameters to set No. Parameter name #13016 SP016 (DDT) #3107 ori_spd Setting Phase alignment deceleration rate Set the single-rotation position alignment deceleration rate for orientation stopping Orientation command speed Set the spindle speed during orientation command Take this tuning method when using orientation. Execute orientations from the maximum rotation speed, every rotation speed and from 180 degrees position. Sample waveforms and tune the spindle in each orientation. (1) Execute an orientation from the maximum rotation speed. Sample waveforms and tune the spindle. (a) Execute with a tool (workpiece) of the largest weight that allows the spindle maximum rotation speed. (b) Execute with the tool (workpiece) of the largest weight allowed to be mounted to the spindle. For how to sample waveforms, refer to the later chapter of "Measuring Waveforms". For checking waveforms and tuning, refer to the later chapter of "Waveform Examples and Tuning Methods". (2) Execute orientations from every rotation speed (every 1000 to 2000 r/min). Sample waveforms and tune the spindle. (3) Confirm the standard value "100" is set in "#3107 ori_spd". Be sure to set "#3107". Otherwise, an orientation from stop is not possible. (4) Execute an orientation from 180 degrees position. Sample waveforms and tune the spindle. (a) Mount a tool (workpiece) of the largest weight allowed to be mounted to the spindle. (b) Stay the spindle at the orientation position. (c) Rotate the spindle to 180 degrees position. (d) Execute an orientation. 43 MITSUBISHI CNC 3 Spindle Tuning Procedure 3.4 Measuring Waveforms Sample waveforms in the following order for tuning. (1) Waveforms in acceleration/deceleration (at maximum rotation speed and every rotation speed) (2) Waveforms in orientation (from maximum rotation speed, every rotation speed and from stop) (3) Others (in synchronous tap, spindle synchronization and spindle/C-axis control) (Note 1) As spindle power characteristics (base rotation speed, rated output max. speed, instantaneous rating, etc.) will change depending on the rotation speed, waveforms at each speed are required in addition to those at max. speed. However, for the waveform type noted later as "Sampled at maximum rotation speed only", waveforms at each speed are not required because the problem shows most clearly at the highest speed. (Note 2) At a point of May, 2008, MS Configurator’s spindle waveform measure functions don’t support all the models or all kinds of data. For exact spindle tuning, waveforms should be sampled from spindle amplifier's D/A output, using a measure device such as a waveform recorder. When using such a device, set the time axis range to either 20ms/DIV or 50ms/DIV. With the range 100ms/DIV or more, the device will not sample an accurate waveform. 3.4.1 Waveforms in Acceleration/Deceleration Sample waveforms in the following order: - Sampled at each rotation speed. (1)Speed - Phase current waveform - When the motor has coil switch specifications, sample both L coil and H coil waveforms at maximum rotation speed. - U and V phases are available. D/A output is as well. (2)Speed - Current feedback waveform - Sampled at each rotation speed. - When the motor has coil switch specifications, sample both L coil and H coil waveforms at maximum rotation speed. (3)Speed - q axis integral term current * q axis integral term current: Controls the current applied to the motor stator’s coil - Sampled at maximum rotation speed only. - When the motor has coil switch specifications, sample both L coil and H coil waveforms at maximum rotation speed. (4)Speed - d axis integral term current * d axis integral term current: Controls the current applied to the motor rotor’s coil (waveforms are unnecessary for IPM spindle, whose rotor is not coil but magnet) Key point Acceleration time is determined by (a) motor’s power characteristics, (b) power of spindle amplifier, and (c) machine’s inertia (including mechanical loss due to friction). In tuning, setting a longer acceleration time is allowed for protecting the machine, while shortening the time is not allowed. For shorter acceleration time, it is necessary to improve the factors (a) to (c) above. 44 Servo/Spindle Tuning Guide 3.4 Measuring Waveforms Settings of D/A output No. and output magnification Set the following parameters when using D/A output. Setting No. Parameter name #13125 SP125 D/A output channel 1 data No. #13126 SP126 D/A output channel 2 data No. #13127 SP127 D/A output channel 1 output scale #13128 SP128 D/A output channel 2 output scale (1)Speed Phase current waveform (2)Speed Current feedback waveform (3)Speed q axis integral term current (4)Speed d axis integral term current 31778 31782 1 31764 3 Differs according to the machine's maximum rotation speed. (Ex.) "20" when maximum speed is 10000r/min, "40" when 5000r/min 2 100 2 2 3.4.2 Waveform in Orientation Sample the following waveform: - Sampled at each rotation speed. Current command Orientation completion signal - The same waveform should be sampled in the orientation from stop. Settings of D/A output No. and output magnification Set the following parameters when using D/A output. No. Parameter name Setting #13125 SP125 D/A output channel 1 data No. 2 #13126 SP126 D/A output channel 2 data No. 16492 #13127 SP127 D/A output channel 1 output scale 100 #13128 SP128 D/A output channel 2 output scale 100 3.4.3 Others For synchronous tap, spindle synchronization and spindle/C-axis control, the followings are required: speed waveform, droop waveform and current feedback waveform. 45 MITSUBISHI CNC 3 Spindle Tuning Procedure 3.5 Waveform Examples and Tuning Methods 3.5.1 Waveforms in Acceleration/Deceleration The following shows the examples of each type waveform before and after tuning. Speed - Current feedback waveform (Before tuning) (After tuning) Point 1: Acceleration end --> constant speed: Make sure that the waveform is as stable as possible (less than half in the range of 50%/ DIV, with two or less fluctuations). Factors of unstableness: (a) speed loop gain is too low or (b) position loop gain is too high Tuning method Set the higher speed loop gain (SP005) or lower position loop gain (SP001). 46 Servo/Spindle Tuning Guide 3.5 Waveform Examples and Tuning Methods Point 2: During constant speed: Make sure that the waveform is as stable as possible (with less current fluctuation). Factors of unstableness: (a) speed loop gain is too low or (b) oscillation Tuning method (1) Set the higher speed loop gain (SP005). (2) If the fluctuation still exists, lower the speed loop gain. Current value will change depending on the load current during rotation. Large current value is acceptable as long as it stays below 70% of the value at acceleration. If the current value is 70% or above, the machine may have problems such as a lack of motor’s capacity or an excessive inertia. Point 3: Constant speed --> deceleration start: Make sure there is no "jump" in the current waveform. "Jump" means the instantaneous fluctuation within 10ms or less time. "Overvoltage" or "Overcurrent" alarm is likely to occur at the current's jump. Tuning method Lower the "#13071 SP071" and "#13072 SP072" values. No. Parameter name #13071 SP071 #13072 SP072 Setting Variable current limit during decel- Set this parameter to adjust the deceleraeration, lower limit value tion time by changing the current limit value Variable current limit during decel- during deceleration according to the motor speed. eration, break point speed 47 MITSUBISHI CNC 3 Spindle Tuning Procedure Speed - Phase current waveform (Before tuning) (After tuning) 48 Servo/Spindle Tuning Guide 3.5 Waveform Examples and Tuning Methods Point 4: During constant speed: Make sure the waveform is as stable as possible (with less current fluctuation). Factors of unstableness: (a) speed loop gain is too low or (b) oscillation Tuning method (1) Set the higher speed loop gain (SP005). (2) If the fluctuation still exists, lower the speed loop gain. Current value will change depending on the load current during rotation. Large current value is acceptable as long as it stays below 70% of the value at acceleration. If the current value is 70% or above, the machine may have problems such as a lack of motor’s capacity or an excessive inertia. Point 5: Constant speed --> deceleration start: Make sure there is no "jump" in the current waveform. Phase current waveform may have more obvious "jump". "Overvoltage" or "Overcurrent" alarm is likely to occur at the current's jump. Tuning method Lower the "#13071 SP071" and "#13072 SP072" values. 49 MITSUBISHI CNC 3 Spindle Tuning Procedure Speed - q axis integral term current (Before tuning) (After tuning) Point 6: After acceleration (during constant speed rotation and deceleration): Make sure that the fluctuation is within ±1V, and the current is stable (with no fluctuation including cyclic current fluctuation) during constant speed. (Ignore the waveform in acceleration.) Factors of unstableness: (a) speed loop gain is too low or (b) oscillation Tuning method (1) Set the higher speed loop gain (SP005). (2) If the fluctuation still exists, lower the speed loop gain. 50 Servo/Spindle Tuning Guide 3.5 Waveform Examples and Tuning Methods Speed - d axis integral term current (Before tuning) (After tuning) Point 7: After acceleration (during constant speed rotation and deceleration): Make sure that the fluctuation is within ±1V, and the current is stable (with no fluctuation including cyclic current fluctuation) during constant speed. (Ignore the waveform in acceleration.) Factors of unstableness: (a) speed loop gain is too low or (b) oscillation Tuning method (1) Set the higher speed loop gain (SP005). (2) If the fluctuation still exists, lower the speed loop gain. 51 MITSUBISHI CNC 3 Spindle Tuning Procedure 3.5.2 Waveform in Orientation Acceleration/deceleration --> Orientation (Current command - Orientation completion signal) Deceleration Orientation Current command Orientation completion signal Point 1: Make sure that the current peak value in orientation is smaller than the value in deceleration. Tuning method If the current value is over the range: Lower the "#13016 SP016" value until the current value is within the range. If the current value is within the range: "#13016 SP016" can be set higher for shortening the orientation time (Point 2). No. #13016 Parameter name SP016 (DDT) Phase alignment deceleration rate 52 Setting Set the single-rotation position alignment deceleration rate for orientation stopping Servo/Spindle Tuning Guide 3.5 Waveform Examples and Tuning Methods Stop (at 180 degrees position) --> Orientation (Current command - Orientation completion signal) Current command Orientation completion signal Point 3: Make sure that the current peak value in orientation is less than 100%. Tuning method If the current value is over the range: Lower the "#3107 ori_spd" value until the current value is within the range. If the current value is within the range: "#3107 ori_spd" can be set higher for shortening the orientation time (Point 4). No. #3107 Parameter name ori_spd Orientation command speed 53 Setting Set the spindle speed during orientation command Revision History Date of revision Jun. 2008 Manual No. BNP-C8027-023A(ENG) First edition created. Revision details