JP4505655B2 - Gear finishing method - Google Patents

Description

  The present invention provides a finishing method of a gear by a revitalization process, and in particular, performs a precision finishing process such as gear shaving by a cutter and gear honing by a grindstone on a gear which is a workpiece under a synchronous rotation with a predetermined synchronization ratio with a cutter or a grindstone. Regarding the method.

  In order to precisely finish gear shaving and gear honing by creating a gear that is a workpiece and a gear-shaped cutter (or grindstone) that meshes with it, the cutter (or grindstone) has a drive motor and drives it. Asynchronous drive method in which the work shafts engaged with each other rotate, and synchronous drive method in which both the cutter shaft (or grindstone shaft) and the work shaft have drive motors and are driven synchronously with a predetermined synchronization ratio. is there.

  Asynchronous and synchronous drive processing methods give an axis crossing angle to the gear-shaped cutter shaft (or grindstone shaft) and the workpiece shaft, and press the cutter (or grindstone) against the tooth surface of the gear to be machined. Processing using relative slip phenomenon.

  In gear shaving and gear honing, it is necessary to finish the surfaces (flanks) on both sides of the teeth equally. Particularly in the synchronous drive system, it is necessary to perfectly match the tooth phase of the cutter (grinding stone) with the tooth phase of the workpiece.

  In gear shaving and gear honing processing, the gear to be processed and the cutter or grindstone are processed in close contact with each other. However, in the pre-processing of the gear to be processed, which is a workpiece, profile error, single, adjacent pitch error, tooth gap flare, etc. There is a dimensional error, and a plurality of teeth with different pitch errors are rotated and processed in close contact with the cutter (or grindstone) and the gear. As the rotation rotates, the teeth of the cutter (or grindstone) and the gear to be processed change sequentially, so in the synchronous drive method in particular, the electrical phase matching point set at the initial meshing stage, the cutter (or grindstone) and the workpiece Deviation occurs in the meshing phase with the gear. If machining is performed with the phase shifted, either the left or right tooth surface will be biased, and the accumulated pitch error will increase, possibly affecting the profile and lead machining accuracy.

  In the asynchronous drive system, the workpiece rotates with the cutter (or grindstone), which is a so-called rotating state. Therefore, the combination state of the cutter (or grindstone), the workpiece gear that is the workpiece, and a plurality of teeth with different pitch errors can be obtained. The phase shift during rotation always changes as it rotates, but the phase shift during rotation always changes. However, since there is no action for forcibly matching the phases as in the synchronous drive method, there is no large phase shift. However, the accumulated pitch error remains unresolved in the pre-processed state. The so-called asynchronous drive method does not improve the cumulative pitch error. In addition, the work tooth surface on the side pressed by the cutter (or grindstone) having a drive motor has extra cutting torque, acceleration torque due to the gear and inertia of the jig for holding the gear, and torque to compensate for friction resistance. It will hang. As a result, the surface pressure differs between the driven tooth surface and the non-driven tooth surface on the opposite side, and the drive-side tooth surface and the non-driven tooth surface, such as shape error, processing distortion and residual stress, each tooth and the left and right facing each other. This is a so-called biasing process that is different for each tooth surface. In order to eliminate this uneven machining and to finish both surfaces of the teeth (flank) evenly, it was necessary to reverse the rotation direction of the cutter during the machining. FIG. 5 shows the relationship between the machining stage from the start to the completion of machining in the asynchronous drive system and the rotation direction of the cutter. In order to reversely rotate the cutter, since the cutter or the grindstone is temporarily stopped and then reversely activated, the machining time is increased accordingly.

On the other hand, since the synchronous drive system has drive motors on both the work shaft and the cutter (or grindstone) shaft, it can be controlled freely including the magnitude and direction of the torque applied to the gear tooth surface. In addition to eliminating the uneven machining, there is no need to stop the cutter (or grindstone) during machining and reverse rotation as in the asynchronous drive system. For example, during machining, the same effect as reverse rotation can be obtained by applying an adjustable torque in one direction up to a predetermined machining and in the opposite direction up to the next predetermined dimension. In this case, the torque may be changed to a desired magnitude in each processing stage. Therefore, it is known that the synchronous drive method performs processing by only one-way synchronous rotation, so that there is no stop / restart time during the processing, and it can be shortened accordingly (for example, see Patent Documents 1 and 2). FIG. 6 shows the relationship from the start of machining to the completion of machining, the rotation direction of the cutter or grindstone, and the torque between the cutter and the workpiece shaft.
JP 2000-317733 A JP 2003-200332 A

  According to the synchronous drive method, since the cutter or the grindstone and the gear are electrically meshed with each other and processed in phase, the left and right tooth surfaces follow the locus of the theoretical contact point. It is possible to cut with tooth pressure that meshes with each other and offsets left and right.

  However, in practice, hobbing, which is the pre-finishing process, or gears after the tooth surface quenching process has variations in single and adjacent pitch error, tooth gap runout, profile and lead accuracy, etc. As a reference for gear shaving and gear honing processing, the pitch of the pre-processing is set as the point where the phase of the workpiece and the cutter (or grindstone) coincided with the electrical phase coincidence point before starting the machining. (Or grindstone) and the teeth of the gear to be machined are determined so that the same teeth do not mesh with each other during rotation. The set mechanical phase coincidence point shifts. That is, as processing is performed, the meshed teeth change and the electrical phase coincidence point is fixed, so that there is a deviation between both initially set phases. When machining in such a state of phase shift, pulsation occurs in the drive torque of the cutter (or grindstone) and the workpiece due to the phase deviation caused by the pre-processing accuracy and the unbalance of the machining allowance due to the processing accuracy, and as a result Variations in tooth surface pressure and uneven cutting due to phase shift occur, and as a result, machining distortion and residual stress differ between each tooth and the left and right tooth surfaces. In addition, it has been difficult to perform high-level finishing by cutting more than one tooth surface due to uneven cutting due to phase shift. To prevent bias cutting, visually check the finished tooth surface, determine the phase shift amount before starting the next gear to be processed, and input it to the NC unit before starting. It is normal to superimpose the input phase shift amount at the coincident point and correct the bias cutting. In this way, judging from the state of the processed gear, the phase correction is biased at the gear to be processed next. Repeated several times until no more shaving, but not complete.

  Next, when the two control motors are started / stopped in a state where the cutter (or grindstone) and the gear to be processed are engaged in the synchronous drive method, the difference in output and the gear and cutter ( (Or grinding wheel) due to the difference in the number of rotations, the difference in the electromechanical constants, and the difference in the moment of inertia applied to each motor shaft, the torque characteristics during acceleration / deceleration, especially the rise (fall) time Is completely different. In addition, since they are engaged with each other and started, the two having different characteristics check each other, and both generate large torque fluctuations. As a result, mechanically induces vibration, scratches the gear tooth surface, and extremely shortens the tool life. In order to prevent this, it is necessary to adjust the characteristics of both control systems to be the same as possible, and it is necessary to have an optimal state where they cannot be controlled, but if the type and shape of the workpiece are different, the rotation speed of the workpiece axis, In order to make a difference in the moment of inertia applied to the cutter (or grindstone) shaft, it was necessary to adjust each time the workpiece was changed.

  As a solution, there is a torque limit item of the control parameter in the NC device, and there is a method of setting one or both of the torque limit parameters to limit the output torque and suppressing mutual check. The motor driven with a large torque at (1) bears the acceleration / deceleration torque of the shaft driven with the opposite small torque. In this case, since the inertia and gear ratio differ for each work change, it is necessary to set a torque limiting parameter for each gear specification. If the torque value to be limited is set to be large, it is possible to solve a gear type with a certain degree of difference, but the start / stop time is increased accordingly.

  When starting / stopping with the control motor engaged, set the acceleration / deceleration constant and gain (control motor axis conversion inertia and control motor inertia ratio) of both control motors to adjust the acceleration / deceleration to the optimum state. However, many factors are involved in the acceleration / deceleration constant setting, and it is impossible for the operator to set or adjust the acceleration / deceleration constant to an optimum state, and a sufficient solution cannot be made.

  Therefore, the first object of the present invention is to suppress the severe torque fluctuation caused by the check between the workpiece and the cutter caused by the uneven acceleration / deceleration characteristics at the time of start / stop under the synchronous drive system, and further start / stop. It is an object of the present invention to provide a gear finishing method that does not cause a long time and does not cause a flaw on a tooth surface and a reduction in tool life.

  The second object of the present invention is to perform asynchronous driving under the synchronous drive system, without torque limitation during processing and phase shift, without switching the rotation direction of the cutter or grindstone in the middle of processing, and further preventing uneven cutting. It is to process in a state close to the same conditions as the method.

  A third object of the present invention is to provide a better gear finishing method by performing torque control in each processing stage under a synchronous drive system.

  In order to achieve the first and second objects, the gear finishing method according to the present invention includes, as a first means, a gear serving as a workpiece and a control motor for driving each of a cutter or a grindstone with a predetermined synchronization ratio. A method of machining a gear that is created and finished by synchronously driving at the same time, and by changing a gain constant set in advance in the control system of at least one control motor, the check torque of both motors at least during acceleration / deceleration One control motor speed gain is made to have a high response or a low response to the command as compared with the other control motor speed gain.

  Further, as a second means, in order to obtain a machining state close to asynchronous machining, at each machining stage except at the time of start / stop, the gain of at least one of the respective control motors is changed to change the direction of the force applied to the tooth surface of the gear. It is characterized by being able to.

  Generally, after completion of machine assembly, various control parameters of each motor are set to standard values specified by the control motor manufacturer. However, for the drive control motor of the cutter (or grindstone) axis and workpiece axis, the workpiece type is If different, the inertia applied to the cutter or grindstone drive motor shaft and the motor shaft that drives the workpiece gear that is the workpiece, and also the rotation speed of the workpiece shaft will be different. The gain may increase and vibration may occur, and if it is too small, the deviation becomes large. Generally, the standard value of the gain is often set to a value close to the limit value in order to make maximum use of the motor characteristics. In order to deal with various gears, a value slightly lower than the standard value is set to prevent transmission of vibration. In that case, the deviation becomes large, and the characteristics of the control motor cannot be fully utilized.

  In order to make maximum use of the characteristics of the control motor, it is necessary to set it to an appropriate value. However, as described above, it is difficult to set it to the operator every time the workpiece type changes. Is set in the data table of the NC controller, and the optimum gain value set in the data table is extracted from the result calculated according to the use of the input gear and cutter (or grindstone). It is advantageous to set the gain to an optimum value by replacing it with gain data. When the standard value of the gain is not the maximum value, the gain may be multiplied by a constant increase rate. In some cases, the gain value is replaced with a predetermined gain value from the standard value.

  The gain can be controlled as part of a machining program or by a machining sequence.

  Some motor control devices have an area for storing data. This area preferably stores acceleration / deceleration constants that do not require much data. That is, in order to prevent occurrence of abnormal torque fluctuation during acceleration / deceleration at the time of starting / stopping, a pre-adjusted gain value or a constant rate is stored in this data area, and the workpiece inputted by the host NC device and The data stored in the host NC unit is specified from the result of calculating the inertia and rotation number converted to each motor shaft based on the specifications of the cutter (or grindstone), and adjusted to the optimum acceleration / deceleration gain constant at start / stop It is preferable.

  In order to achieve the third object, the gear finishing method according to the present invention includes, as a third means, a gear shaft or a cutter (or a grindstone) in a plurality of processing stages excluding acceleration / deceleration at start / stop. ) Any one of the shafts is controlled according to a torque pattern set in advance according to the plurality of machining steps. As a result, in each step of the machining stage, either the cutter (or grindstone) shaft or the workpiece shaft is torque controlled, and machining is performed under the optimum conditions for the gear to be machined. The third means also depends on the first means during acceleration / deceleration.

  The torque pattern is preferably formed by a target torque value set in accordance with each step of roughing, finishing, dwell, and back movement in a machining cycle. It is preferable that the control system has a torque compensation circuit for controlling to the target torque.

  In addition, a third shaft that rotates synchronously with the gear shaft or cutter (or grindstone) shaft that is the object to be controlled is set, and the gear shaft or cutter (or grindstone) shaft that is the object to be controlled is A synchronization command is sent from the NC device so as to rotate in synchronization with the shaft 3, and the torque compensation circuit compares the actual torque of the gear shaft or cutter (or grindstone) shaft to be controlled with the target torque value to produce a torque deviation. And an addition unit that superimposes the torque deviation on the synchronization command to the gear shaft or cutter (or grindstone) shaft to be controlled.

  That is, in addition to the cutter (or grindstone) axis or the workpiece axis, a new third axis that is synchronized with the axis for torque control is set, and a preset target torque value is stored in the data table, or part of the machining program As described above, an appropriate torque in each process is programmed, and the command torque value is compared with the actual torque value fed back from the torque-controlled control motor, and the deviation is calculated to obtain torque information. The host NC device issues a synchronization command to the newly set third axis and the axis for torque control, and the position command of the host NC device for either the cutter (or grindstone) or workpiece axis for torque control, The above torque information is superimposed, and the gear is processed with the target torque for all the processes. The third axis may be a so-called virtual axis that does not have a control motor and a control amplifier, or a so-called real axis that has a control motor and its control amplifier.

  According to the first means of the present invention, under the synchronous drive method, by changing a gain constant set in advance in the control system of at least one control motor, the motors are controlled at least during acceleration / deceleration. The desired torque curve can be obtained without limiting the torque from start to processing and stop by making one control motor have a high response or low response to the command compared to the other control motor so as to suppress the torque. In addition, it is possible to suppress severe torque fluctuations during acceleration / deceleration at start / stop, to achieve high-precision finishing, and to prevent a reduction in tool life.

  According to the second means of the present invention, the value of the gain constant of the control motor is changed as in the first means, and the cutter (or grindstone) shaft is not simply processed with a desired torque curve. Alternatively, the target torque (torque magnitude and direction) at each machining stage is set in one of the workpiece axis drive control motors, and machining is performed with an ideal magnitude torque and a torque curve including the direction. Therefore, with the same gear type, all the workpieces can be processed with the same target torque value. This torque control axis is implemented by either a cutter (or grindstone) axis or a work axis depending on the gear specifications.

  First, a first embodiment of the present invention will be described below with reference to the accompanying drawings. 1 and 2 show the configuration of a gear finishing apparatus to which the gear finishing method according to the present invention can be applied, and FIG. 3 is a typical block diagram of its control system. In addition, the same code | symbol was attached | subjected to the same component through all embodiment and all the figures.

  In this gear finishing device, as shown in the figure, a work shaft (arbor) 3 is sandwiched between a head stock chuck 1 and a tail stock center 2, and a work (gear) W is fixed to the work shaft (arbor) 3. Has been. The chuck 1 is driven by a control motor 4 together with the work shaft 3. Further, the cutter (or grindstone) C is arranged so that it can be engaged with and released from the workpiece W. The drive shaft 5 of the cutter (or grindstone) C in FIG. 1 is driven by a cutter (or grindstone) shaft control motor 6. In FIG. 2, the cutter (or grindstone) C is driven by the control motor 6 via a gear 5a for rotating it and a gear 5b meshing with the gear 5a. In the illustrated example, the control motor 4 is a built-in AC spindle motor, and the control motor 6 is an AC digital servo motor in the case of FIG. 1, and an AC spindle motor or an AC digital servo motor in the case of FIG.

  The control motors 4 and 6 are driven and controlled by amplifiers (control devices) 7 and 8 that control their positions, speeds, and torques. The amplifiers 7 and 8 receive position commands from the NC device 9 which is a host control device. The amplifiers 7 and 8 receive information on the position and speed from the encoders 10 and 11 and further receive information on the torque from the control motor, and control the control motors 4 and 6 so as to follow the command of the host controller 9 faithfully. Yes.

  The flow of commands will be described with reference to FIG. In FIG. 3, the host control device (NC device) 9 sends a master position command of the drive control motor 6 to the cutter (grinding stone) shaft amplifier 8, and the control motor 4 that drives the workpiece W is a slave of the cutter (grinding stone) C. Then, a slave position command having a synchronization ratio α to the master position command is sent to the workpiece axis control amplifier 7 so that the cutter (or grindstone) C and the workpiece W are synchronously driven. The synchronization ratio α is determined by the ratio of the number of teeth of the cutter C and the workpiece W and the configuration of each drive system. The master may be the work axis and the slave may be the cutter axis. This depends on which of the correction axes is advantageous.

  In the amplifier 8 on the cutter (grinding stone) C side, the inputted master position command and the position feedback signal detected by the encoder 11 are collated, and the obtained position deviation is sent to the position gain Kp. This part is called position control. The signal calculated by the position gain is sent to the next speed control as a speed command. The speed command is checked against the speed feedback signal, and the speed deviation is calculated by speed control. For speed control, PI (proportional / integral) control is basically used. By adjusting the proportional gain Kp and the integral gain Ki, the control motor can be controlled in a state closest to the command value. FIG. 3 shows basic PI control. The output calculated by the speed control is sent to the next current control as a current (torque) command, and the control motor is further controlled by a current amplifier.

  The first and second means of the present invention control the torque characteristic by rewriting the constant value of the integral gain in the speed control or multiplying the gain constant by a constant rate. The proportional gain is desirably set to a value just before oscillation or a standard value. Note that the torque characteristic can be controlled by cutting the accumulated pulse, overriding the gain constant, or the like instead of multiplying the gain by a constant rate or rewriting the gain.

  First, in order to obtain an optimum operating state in the normal operation in which the cutter (or grindstone) C and the workpiece W are not meshed with each other, the cutter (or grindstone) C side and the workpiece W side are related to the specifications of the cutter (grindstone) and the workpiece gear, respectively. Standard gain constants corresponding to information, for example, outer shape, number of teeth, tooth width, etc. are extracted from the data table and replaced with this value.

  As the standard gain constant, a numerical value obtained by trial and error is set in the data table of the host control device 9 in advance. The standard gain constant is generally a value given by the control motor manufacturer.

  When there is a memory (ROM) area in the control motor amplifier, it is desirable to set a value or a reduction rate that can be fixed to some extent, such as start / stop, in the memory area.

  A gain command or constant rate (decrease rate, increase rate, etc.) that matches the command is extracted from preset gain values stored in advance by a gain command programmed by the machining program (using an auxiliary function such as an M code). In the acceleration / deceleration of start / stop, the standard gain constant is rewritten in each of the rough machining stage, the finishing machining stage, and the dwell, or the standard gain constant is multiplied by a constant rate and machining is performed with an ideal torque curve. Each set of stages is programmed into a machining program or performed in a predetermined sequence.

  Hereinafter, the relationship between gain and torque will be described in detail with reference to the graph shown in FIG. In this example, the reduction rate is multiplied by the value of the gain Ki of the workpiece axis drive control motor, but the gain of the cutter (grinding stone) axis drive control motor may be adjusted depending on the specifications of the workpiece and the cutter (grinding stone).

  In the example of FIG. 4A, first, in the acceleration stage from the start to the arrival of the command rotational speed, the speed integral gain of the work axis control motor 4 is reduced by 20% from the initial set value (standard gain constant). . As a result, the response speed of the cutter (grinding stone) axis control motor is relatively faster (high response) than the workpiece axis control motor, and the work axis is somewhat rotated with the cutter (grinding stone) axis. Since the check torque is not output, it is smoothly accelerated. Since the workpiece shaft is not torque limited, the cutter (grinding stone) shaft motor does not have to bear the acceleration torque of the workpiece shaft so much. At the time of acceleration that is difficult to synchronize, the cutter (grinding stone) takes the lead in this way, so that each other does not restrain each other and accelerates smoothly, and abnormal torque fluctuations that cause vibration do not occur. It is possible to prevent the tool life from being shortened without causing any damage to the tooth surface of the workpiece.

  Next, when the designated rotational speed is reached, the rough machining stage is entered. In this figure, the speed integral gain (Ki) of the workpiece axis control motor is set slightly higher than the normal value (90% of the oscillation limit). In this case, since the response speed of the workpiece axis is increased, the cutter (grinding stone) axis is pushed by the workpiece axis and becomes free.

  In the next finishing step, the workpiece shaft speed integral gain is multiplied by a reduction rate of 20%. In this state, the response of the workpiece axis is delayed, and the response of the cutter (grinding stone) shaft is in a normal state, so that the cutter (grinding stone) axis pushes the workpiece axis.

  By changing the gain value in this way, it is possible to perform the same operation as the effect of normal rotation and reverse rotation asynchronously.

  Next, the back movement stage is entered, but since the gain remains unchanged, the cutter (grinding stone) shaft is in a pushing state.

  Next, it becomes a stop operation stage. Here, it is reduced by 20%, which is the same as at the time of starting, and the cutter (grinding stone) C takes the lead and prevents abnormal fluctuations in the work shaft torque, so the speed is smoothly reduced. As a result, the work tooth surface is not damaged and the tool life is also prevented.

  4 (B) to 4 (D) show other control examples in which various speed gains on the workpiece side are set. Depending on the specifications of the workpiece and the cutter (grinding stone), the gain constant value on the cutter (grinding stone) C side may be set at each stage. In this way, processing can be performed by applying a surface pressure to any one of the left and right tooth surfaces without limiting the torque and without shifting the phase.

  Next, a second embodiment of the present invention will be described. Also in the second embodiment, the finishing is performed by synchronously driving a control motor that drives each of the gears and cutters (grinding stones) serving as workpieces at a predetermined synchronization ratio.

  In the second embodiment, the machining method of the first embodiment is applied during acceleration / deceleration of start / stop, and the machining stage (that is, the stage excluding acceleration / deceleration) is different from the machining method of the first embodiment. .

  In the machining method according to the second embodiment, first, a new third axis is set in addition to the workpiece axis and the cutter (grindstone) axis. This axis may be a so-called virtual axis that does not have a control amplifier and a control motor, or a real axis other than a work axis and a cutter (grinding stone) axis that has a control amplifier and a control motor.

  Next, individual target torques in each processing stage are set. The machining stage refers to all machining stages except for acceleration / deceleration at start / stop. The processing steps are generally roughing, dwell, finishing, dwell, back movement and dwell. Note that “dwell” means a step of cutting the amount of displacement by stopping the temporary feeding. The dwell is generally performed at the end point of the rough machining stage and the end point of the machining.

  The target torque value is designated by programming in the machining program. In this machining program, a desired torque value is programmed for each process. When the machining program is executed, a torque value command designated in each process is issued. FIG. 7 is a block diagram showing the control system having a torque compensation circuit for controlling the target torque. The designated torque value is collated with the actual torque fed back and becomes a torque deviation. The torque deviation is calculated, and the calculated signal is superimposed on the position command of the NC device, which is the higher-order control device for the shaft that performs torque control, by issuing a command for synchronizing the newly set third axis.

  In this way, by superimposing the calculated torque deviation on the position command of the host NC device, machining according to a constant torque pattern at the machining stage is performed with the torque value specified at each machining stage. Can do. The target torque includes the magnitude and direction (±), and can be processed by applying a surface pressure to each of the left and right tooth surfaces.

It is the schematic which shows one Embodiment of the gear finishing apparatus which can apply the finishing method of the gear which concerns on this invention. It is the schematic which shows other embodiment of the gear finishing apparatus which can apply the finishing method of the gear concerning this invention. It is a block diagram which shows the control system of the gear finishing apparatus of FIG.1 and FIG.2. It is a graph which shows the change of the cutter (grinding stone) shaft drive torque applied to the control system of FIG. 3 according to a process step. It is a diagram which shows the relationship between the rotation stage of a cutter (grinding stone), and the torque of a workpiece | work axis | shaft from the starting to the completion of a process in the conventional finishing method of an asynchronous drive system. It is a diagram which shows the relationship between the process stage from the starting to the completion of a process in the finishing process method in a synchronous drive system, the rotation direction of a cutter, and the torque of a workpiece | work axis | shaft. It is a block diagram which shows the principal part of the torque control system regarding 2nd Embodiment.

Explanation of symbols

4, 6 Control motor 7, 8 Amplifier 9 Host controller C Cutter W Workpiece

Claims (10)

A processing method of a gear that is created and finished by synchronously driving a control motor that drives each of a gear and a cutter or a grindstone as a workpiece with a predetermined synchronization ratio,
By changing a gain constant set in advance in the control system of at least one control motor, the control motor speed gain of one control motor speed is controlled so as to suppress the check torque of both motors at least during acceleration / deceleration. A gear finishing method characterized by having a high response or a low response compared to a gain. 2. The gear finishing method according to claim 1, wherein the gain constant is changed by multiplying a preset gain constant by a constant rate. 3. The gear finishing method according to claim 1, wherein the gain constant is changed in real time during execution of the machining program. Each gain constant adjusted in advance according to the specifications such as the type and shape of the cutter or the grindstone and the gear is recorded in a data table in the NC device, and based on input information regarding the specifications of the cutter or the grindstone and the gear. A gear constant finishing method according to any one of claims 1 to 3, wherein a gain constant is extracted from the data table, and a preset gain constant is changed according to the extracted gain constant. . Various information related to the specifications of the gears and cutters or grindstones that are workpieces are input to the NC unit. From the input information, the drive motor shaft equivalent inertia and rotation speed of the gears and cutters or grindstones are calculated. 5. The gear finishing method according to claim 4, wherein a gain constant adapted to the drive motor is extracted from the data table based on a calculation result. The gear constant according to any one of claims 1 to 5, wherein the change of the gain constant is executed according to the plurality of machining stages even in a machining stage excluding acceleration / deceleration at start / stop. Finishing method. In a plurality of machining stages excluding acceleration / deceleration at start / stop, either the gear shaft or the cutter (grindstone) shaft is controlled according to a torque pattern set in advance according to the plurality of machining stages. A finishing method for a gear according to any one of claims 1 to 5. The gear according to claim 7, wherein the torque pattern is formed by a target torque value set in accordance with each step of roughing, finishing, dwell, and back movement in a machining cycle. Finishing method. The gear finishing method according to claim 7 or 8, further comprising a torque compensation circuit for controlling the target torque in a control system. The gear shaft, cutter shaft, or grindstone shaft to be controlled is set to a third axis that rotates synchronously with the gear shaft, cutter shaft, or grindstone shaft, and the gear shaft, cutter shaft, or grindstone shaft to be controlled is set to the third axis. Synchronous command is sent from the NC unit to rotate synchronously, and the torque compensation circuit compares the actual torque of the gear shaft, cutter shaft or grindstone shaft to be controlled with the target torque value and outputs a torque deviation And an adder for superimposing the torque deviation on a command to synchronize the torque deviation with a third axis on the synchronization command to the gear shaft, cutter shaft or grindstone shaft to be controlled. The gear finishing apparatus as described.

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