JP2016078223A - Control device and control method for controlling machine tool for controlling synchronous operation of main spindle and feed shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten cycle time by carrying out control for exhibiting the acceleration performance of a main spindle to a maximum limit with a simple configuration in a machine tool for executing tap processing by the synchronous operation of the main spindle and a feed shaft.SOLUTION: A main spindle control unit 18 includes an initial operation control unit 30 for accelerating and rotating a main spindle 12 from a processing start position to a target screw depth with a highest rotational speed V0 fed from a numerical value control unit 16 set as a target value at maximum performance, a maximum acceleration detection part 32 for detecting maximum acceleration A0 based on a rotation position FBS during accelerated rotation, a residual rotation amount detection part 34 for detecting the residual rotation amount Sr of the main spindle 12 from a current position to the target depth based on a total rotation amount S0 fed from the numerical value control unit 16 and the rotation position FBS, a current speed detection part 36 for detecting the current speed Vc of the main spindle 12 based on the rotation position FBS, and a positioning operation control unit 38 for decelerating and rotating the main spindle 12 at maximum performance to reach the target depth based on the maximum acceleration A0, the residual rotation amount Sr, and the current speed Vc after the accelerated rotation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a machine tool control device that controls synchronous operation of a main shaft and a feed shaft. The present invention also relates to a machine tool control method for controlling synchronous operation of a main shaft and a feed shaft.

  In a machine tool that performs tapping by synchronous operation of a main shaft and a feed shaft, various configurations for improving machining accuracy and shortening cycle time have been proposed. For example, Patent Document 1 is a screw machining device that performs tapping while the feed shaft follows the rotation of the main shaft, and calculates a feed command value for the feed shaft from the rotation speed and rotational acceleration of the main shaft and the screw pitch. In addition, a screw machining apparatus is disclosed in which the feed command value is corrected in accordance with the actual rotational position of the spindle, thereby improving the accuracy of tapping. Patent Document 2 discloses a spindle motor acceleration / deceleration control method for a numerical controller that performs synchronous control of a spindle and a feed axis for tapping, where the numerical controller is an acceleration / deceleration command corresponding to the output characteristics of the spindle. A spindle motor acceleration / deceleration control method is disclosed in which the response of the spindle is improved by controlling the spindle in accordance with this acceleration / deceleration command, and as a result, the cycle time can be shortened.

Japanese Patent No. 2629729 Japanese Patent No. 3553741

  In a machine tool that performs tapping by synchronous operation of the main shaft and the feed shaft, the cycle time is generally determined depending on the acceleration capability of the main shaft. With a simpler configuration, the numerical control device can perform the spindle operation without performing preliminary work that requires advanced technology, such as parameter settings and adjustments required for creating acceleration / deceleration commands corresponding to the output characteristics of the spindle. It is desired that the cycle time can be shortened by performing control to maximize the acceleration capability.

  One aspect of the present invention is a machine tool control device that controls synchronous operation of a spindle and a feed axis, a numerical control unit that creates a spindle command and a feed axis command based on a tap machining program, and a spindle according to the spindle command A spindle control unit that controls the rotation operation of the spindle, a rotation detection unit that detects the rotation position of the spindle, and a feed axis control unit that controls the feed operation of the feed axis based on the rotation position of the spindle according to the feed axis command. The numerical control unit obtains the total spindle rotation speed and maximum rotation speed from the machining start position to the target screw depth from the tapping program, and uses the total rotation speed and maximum rotation speed as the spindle command. A spindle command output unit to be sent to the control unit. The spindle control unit has an initial operation control unit for accelerating and rotating the spindle at the maximum capacity from the machining start position to the target screw depth with the maximum rotation speed as a target value. The maximum acceleration detection unit that detects the maximum acceleration based on the rotation position of the spindle during acceleration rotation at the shaft, and the remaining rotation of the spindle from the current position to the target screw depth based on the total rotation amount and the rotation position of the spindle A remaining rotation amount detection unit for detecting the amount, a current speed detection unit for detecting the current speed of the main spindle based on the rotation position of the main shaft, and a maximum acceleration, a remaining rotation amount, and a current speed after the acceleration rotation at the maximum capacity. And a positioning operation control unit that rotates the main shaft at a reduced speed to reach the target screw depth.

  Another aspect of the present invention is a method for controlling a machine tool that controls synchronous operation of a main shaft and a feed shaft, wherein the control device includes a total amount of rotation of the main shaft from a machining start position to a target screw depth. The maximum rotation speed is acquired from the tap machining program, the maximum rotation speed is set as the target value, the spindle is accelerated from the machining start position to the target screw depth at the maximum capacity, and the spindle rotates during the acceleration rotation at the maximum capacity. The maximum acceleration is detected based on the position feedback value, the remaining amount of rotation of the main spindle from the current position to the target screw depth is detected based on the total rotation amount and the rotation position feedback value, and the main spindle is detected based on the rotation position feedback value. A control method that detects the current speed of the spindle and, after accelerating rotation at the maximum capacity, rotates the spindle at the maximum capacity to reach the target screw depth based on the maximum acceleration, the remaining rotation amount, and the current speed. It is.

  According to the control device according to one aspect, when the spindle performs a cutting operation from the machining start position to the target screw depth, the numerical controller controls only the total rotation amount and the maximum rotation speed of the spindle relative to the spindle control unit. As the spindle command, and the spindle control unit executes the cutting operation by accelerating the spindle with the maximum output that uses the maximum allowable current for the maximum rotation speed according to the spindle command, and the maximum acceleration Based on the remaining amount of spindle rotation and the current speed that are detected sequentially, the cutting operation to the target screw depth is continuously executed in the shortest time while the spindle is decelerated at the maximum deceleration to reach the target screw depth. This eliminates the need to set and adjust parameters for creating acceleration / deceleration commands corresponding to the output characteristics of the spindle for the numerical control unit, and maximizes the spindle's acceleration capability with a simpler configuration. Performing deceleration control, it is possible to shorten the cycle time of tapping.

  According to the control method according to another aspect, an effect equivalent to the effect of the control device described above is exhibited.

It is a functional block diagram which shows the structure of one Embodiment of a machine tool control apparatus. It is a flowchart which shows the cutting operation control method of the tap process as one Embodiment of the machine tool control method. It is a figure which shows an example of operation | movement of the main axis | shaft in embodiment of FIG. It is a figure which shows the other example of operation | movement of the main axis | shaft in embodiment of FIG. It is a figure which shows the further another example of operation | movement of the main axis | shaft in embodiment of FIG. It is a figure which shows the further another example of operation | movement of the main axis | shaft in embodiment of FIG. It is a flowchart which shows the return operation control method of the tap process as one Embodiment of the machine tool control method. It is a functional block diagram which shows the structure of the modification of the control apparatus of FIG. It is a functional block diagram which shows the structure of the other modification of the control apparatus of FIG. It is a flowchart which shows the cutting and return operation | movement control method of the tap process as other embodiment of the machine tool control method. It is a figure which shows an example of operation | movement of the main axis | shaft in embodiment of FIG. It is a figure which shows the other example of operation | movement of the main axis | shaft in embodiment of FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.

  FIG. 1 is a functional block diagram showing the configuration of a machine tool control apparatus 10 according to an embodiment. In a machine tool (for example, a lathe, a drilling machine, a machining center, etc.) that performs tapping by synchronous operation of the main shaft 12 and the feeding shaft 14, the control device 10 considers the screw pitch specified by the tapping program P. On the other hand, the synchronous operation that operates so as to follow the rotational operation of the main shaft 12 is controlled. Although not shown, the main shaft 12 is a control shaft that is set in a drive device such as a servo motor that rotates a gripping portion that grips a workpiece or a tool at a speed necessary for processing. Although not shown, the feed shaft 14 is a control shaft set in a drive device such as a servo motor that feeds and moves a support portion that supports a workpiece or a tool at a speed necessary for machining. For example, in a lathe, a tool can be linearly fed with a feed shaft 14 to a workpiece rotating on the main shaft 12, or a work rotated with the main shaft 12 can be linearly fed to the tool with a feed shaft 14. In the drilling machine, the tool rotating on the main shaft 12 can be linearly fed to the workpiece by the feed shaft 14, or the workpiece can be linearly fed by the feed shaft 14 to the tool rotating on the main shaft 12. In either case, the feed shaft 14 having a relatively large margin for operating acceleration / deceleration torque operates so as to follow the spindle 12 having a relatively small margin for operating acceleration / deceleration torque, thereby reducing synchronization errors. Thus, processing accuracy can be improved. In the present invention, the configuration of the machine tool is not particularly limited.

  The control device 10 includes a numerical control unit 16 that generates a spindle command CS and a feed axis command CF based on the tap machining program P, a spindle control unit 18 that controls the rotation operation of the spindle 12 according to the spindle command CS, and the rotation of the spindle 12. A rotation detection unit 20 that detects the position, and a feed axis control unit 22 that controls the feed operation of the feed shaft 14 based on the rotation position detected by the rotation detection unit 20 in accordance with the feed axis command CF. The numerical control unit 16 includes a program interpretation unit 24 that interprets the tap machining program P, a spindle command CS that generates a spindle command CS according to the interpretation of the program interpretation unit 24, and a spindle command output unit 26 that sends the spindle command CS to the spindle control unit 18. And a feed axis command output unit 28 that generates a feed axis command CF according to the interpretation of the program interpretation unit 24 and sends the feed axis command CF to the feed axis control unit 22. The numerical control unit 16 can have a hardware configuration of a known CNC device.

Prior to the start of tap machining, the spindle command output unit 26 determines from the command value of the tap machining program P interpreted by the program interpretation unit 24 to the target screw depth (rotation position) from the machining start position (rotation position). The total rotation amount S0 and the maximum rotation speed V0 of the spindle 12 are acquired, and the total rotation amount S0 and the maximum rotation speed V0 are sent to the spindle control unit 18 as a spindle command CS. For example, when the tapping program P includes a command to machine a female screw having a screw pitch of 1.25 mm and a screw depth of 30 mm with a maximum rotational speed V0 of the spindle 12 of 3000 / min, the processing reaches the target screw depth from the machining start position. Since the total rotation amount S0 of the main shaft 12 in the interval is 30 ÷ 1.25 = 24 (rev), the main shaft command output unit 26 sets V0 = 3000 (min ⁻¹ ) and S0 = 24 (rev) to the main shaft. Notify the control unit 18. Thus, the spindle command CS does not include a position command or an acceleration / deceleration command for rotating the spindle 12 to the target screw depth.

  The main shaft control unit 18 controls the rotation operation of the main shaft 12 by general feedback control using the rotation position (feedback value, hereinafter referred to as the rotation position FBS) of the main shaft 12 detected by the rotation detection unit 20. In addition to the feedback value of the feed position of the feed shaft 14, the feed shaft control unit 22 uses the rotational position FBS of the main shaft 12 to control the feed operation of the feed shaft 14 that follows the operation of the main shaft 12 by feedback control. The rotation detection unit 20 can acquire the rotation position FBS from the output of a position detector (not shown) such as an encoder that detects the operating position of the drive device of the main shaft 12.

The spindle control unit 18 uses the maximum rotational speed V0 (min ⁻¹ ) sent from the spindle command output unit 26 as a target value, and initially rotates the spindle 12 at maximum capacity from the machining start position to the target screw depth. The operation controller 30, the maximum acceleration detector 32 that detects the maximum acceleration A 0 (min ⁻¹ / s) based on the rotational position FBS during acceleration rotation at the maximum capacity, and the total rotation sent from the spindle command output unit 26 Based on the amount S0 (rev) and the rotational position FBS, a residual rotational amount detector 34 that detects the residual rotational amount Sr (rev) of the main shaft 12 from the current position (rotational position) to the target screw depth, the current speed detecting section 36 for detecting the current speed Vc ^{(min -1)} of the spindle 12 based on the position FBS, after acceleration rotation at maximum capacity, maximum acceleration A0 and the remaining amount of rotation Sr current based on the speed Vc The spindle 12 and rotated at a speed at maximum capacity to reach the target thread depth and a positioning operation control unit 38. In one embodiment, the positioning operation control unit 38 can be configured to cause the spindle 12 to rotate at a reduced speed with the maximum capacity and to stop at the target screw depth.

  FIG. 2 shows a cutting operation control method of the spindle 12 in tapping as an embodiment of a machine tool control method executed by the control device 10. Hereinafter, the detailed configuration of the control device 10 will be described with reference to the tapping process control flow illustrated in FIG. First, in step S1, the numerical control unit 16 (spindle command output unit 26) instructs the main shaft control unit 18 of the total rotation amount S0 and the maximum rotation speed V0 of the main shaft 12. In step S2, the spindle control unit 18 (the initial motion control unit 30, the maximum acceleration detection unit 32, and the remaining rotation amount detection unit 34) uses the spindle 12 as a drive source with the maximum rotation speed V0 as the target speed from the machining start position. Tap processing is executed by accelerating rotation with the maximum capacity utilizing the allowable current to the maximum, and the maximum acceleration A0 during that time is detected, and the remaining rotation amount Sr from the current position is sequentially detected. The spindle control unit 18 notifies the numerical control unit 16 of the detected remaining rotation amount Sr each time it is detected.

  Next, in step S3, the spindle control unit 18 (current speed detection unit 36) sequentially detects the current speed Vc during acceleration rotation at the maximum capacity, and the current speed Vc reaches the maximum rotation speed V0 each time it is detected. Judge whether or not. If Vc has not reached V0, in step S4, the spindle control unit 18 determines whether or not the remaining rotation amount Sr is less than or equal to ½ of the total rotation amount S0. If Sr is less than or equal to 1/2 of S0, in step S5, the spindle control unit 18 continues the tapping process by rotating the spindle 12 at a reduced speed with the maximum capacity using the allowable current of the drive source to the maximum. Run. If Sr is not less than 1/2 of S0, the process returns to step S3.

  Referring now to FIG. 3, when the remaining rotational speed Sr becomes ½ of the total rotational speed S0 before the current speed Vc reaches the maximum rotational speed V0 (the determinations in steps S3 and S4 are both YES) The movement of the spindle 12 in the case) is represented by a speed-time curve. In FIG. 3, Vb is set in advance on the main shaft 12 as a rotational speed (for example, a base speed of a servo motor) that can be accelerated with a constant torque (that is, a constant acceleration) from the start to the speed Vb. For example, it can be stored as one of the control parameters in a memory (not shown) of the control device 10. In practice, the speed Vb may be equal to or lower than the base speed of the servo motor (a speed in consideration of the speed reduction ratio when a speed reduction ratio exists between the servo motor and the main shaft 12).

  The acceleration rotation with the maximum capacity of the main shaft 12 in step S2 is executed at times T1 and T2 in FIG. 3, and the maximum acceleration A0 is detected during the constant acceleration at time T1. When the rotational speed of the main shaft 12 exceeds Vb, the acceleration of the main shaft 12 gradually decreases from the maximum acceleration A0 due to, for example, the characteristics of the servo motor. Time point A when the remaining rotation amount Sr becomes 1/2 of the total rotation amount S0 (that is, the rotation amount from the start of machining becomes 1/2 of the total rotation amount S0) (when the determination in step S4 becomes YES) ), The operation of the main shaft 12 is changed from the acceleration rotation to the deceleration rotation, and at time T3, the decelerating rotation with the maximum capacity of the main shaft 12 in step S5 is executed. At time T3, the spindle 12 is decelerated and rotated from the point A using the speed Vb as a target value. During this time, the deceleration of the spindle 12 gradually increases due to, for example, the characteristics of the servo motor. Even during decelerating rotation at the maximum capacity, the spindle control unit 18 (remaining rotation amount detection unit 34, current speed detection unit 36) sequentially detects the remaining rotation amount Sr and the current speed Vc from the current position of the spindle 12. Thus, at time T1 to T3, the spindle control unit 18 controls the speed of the spindle 12 (a stepped speed command is illustrated by a broken line).

After step S5, the spindle control unit 18 (positioning operation control unit 38) monitors the remaining rotation amount Sr (rev) and the current speed Vc (min ⁻¹ ) that are sequentially detected, and the current speed Vc (min ⁻¹ ) to Sr = 0 (that is, the target screw depth is reached) when the vehicle is decelerated at the maximum deceleration A0 (negative value) corresponding to the maximum acceleration A0 (min ⁻¹ / s). 3 is obtained as the absolute value of the remaining rotation amount Sr (negative value) as seen from the point of Sr = 0.
Formula: (Vc / 60) ² = 2 × | A0 | / 60 × | Sr |
| Sr | = Vc ² / | A0 | / 120

Here, in this embodiment, it is assumed that the spindle 12 is decelerated from the point B at a constant maximum deceleration A0. Therefore, at the point B, it is assumed that the current speed Vc of the main shaft 12 has reached Vb. That is, the position | Sr |
| Sr | = Vb ² / | A0 | / 120
Can be obtained as

In this embodiment, it is assumed that torque required for acceleration of the main shaft 12 (hereinafter referred to as acceleration torque) and torque required for deceleration (hereinafter referred to as deceleration torque) are equal to each other. In general, a load (resistance) on the mechanical structure is generated during the rotation of the main shaft 12, and the acceleration torque becomes larger than the deceleration torque. Therefore, when the acceleration torque and the deceleration torque are equal, the maximum speed is compared when compared with the same speed change. The acceleration time at the ability is longer than the deceleration time at the maximum ability. Therefore, in practice, the main shaft 12 reaches the speed Vb in a time shorter than the time T2 after decelerating from the point A, and the position | Sr | at this time is | Sr |> Vc ² / | A0 | / 120.
After that, by rotating at a constant speed Vb for a minimum time,
| Sr | = Vb ² / | A0 | / 120
The point B is reached (FIG. 3).

Referring to FIG. 2 again, in step S6, the spindle control unit 18 (positioning operation control unit 38) determines that the absolute value | Sr | of the remaining rotation amount at the current position of the spindle 12 is | Sr | = Vb ² / | A0. It is determined whether or not | / 120 is satisfied (that is, whether or not the rotational position of the spindle 12 has reached point B). When | Sr | = Vb ² / | A0 | / 120 is satisfied, in step S7, the spindle control unit 18 (positioning operation control unit 38) decelerates and rotates the spindle 12 at the maximum deceleration A0, and Sr = 0. A command (in one embodiment, a command to stop at the target screw depth) for reaching the point (namely, the target screw depth) is created, and the position of the spindle 12 is controlled by this command. If | Sr | = Vb ² / | A0 | / 120 is not satisfied, the determination is repeated until this equation is satisfied. The spindle 12 rotates at a maximum deceleration A0 from the point B toward the target screw depth in accordance with a command from the spindle control unit 18 (positioning operation control unit 38), executes tapping, and Sr = 0. The target screw depth is reached (in one embodiment, it stops at the target screw depth). As described above, at the time T4 (FIG. 3) from the point B to the target screw depth, the spindle control unit 18 controls the position of the spindle 12 (constant acceleration speed command is illustrated by a broken line. ).

  If it is determined in step S3 that the current speed Vc has reached the maximum rotational speed V0, in step S8, the spindle control unit 18 determines that the spindle 12 from the machining start position when the maximum rotational speed V0 has been reached. The rotation amount (that is, the rotation position FBS) is stored as the acceleration rotation amount Sa. In step S9, the spindle control unit 18 determines whether or not the remaining rotation amount Sr is equal to or less than the acceleration rotation amount Sa. If Sr is equal to or less than Sa, the process proceeds to step S5, and then steps S6 and S7 are executed to perform processing up to the target screw depth. If Sr is not less than or equal to Sa, the determination is repeated until Sr becomes less than or equal to Sa.

  While the main shaft control unit 18 controls the rotation operation from the machining start position of the main shaft 12 to the target screw depth, the feed shaft control unit 22 uses the rotation position FBS of the main shaft 12 to change the feed shaft 14 to the operation of the main shaft 12. The feed operation is performed under control to follow. The numerical control unit 16 monitors the remaining rotation amount Sr notified from the spindle control unit 18 while the main shaft control unit 18 executes the processes of Steps S1 to S9, and the remaining rotation amount Sr is a first predetermined value. When the value becomes (minimum value close to zero) or less, it is determined that tapping has reached the target thread depth.

  FIG. 4 shows the operation of the spindle 12 when the current speed Vc reaches the maximum rotational speed V0 before the remaining rotational amount Sr becomes 1/2 of the total rotational amount S0 (when the determination in step S3 is NO). It is shown by a speed-time curve. As shown in FIG. 4, the maximum speed acceleration rotation of the main shaft 12 in step S2 is executed at time T1 and T2, and the current speed Vc of the main shaft 12 reaches the maximum rotation speed V0, and then is constant over time T5. The main shaft 12 rotates at the speed V0 and the tapping is continued, and the operation of the main shaft 12 is performed at a time A (when the determination in step S9 is YES) when the remaining rotation amount Sr becomes equal to the acceleration rotation amount Sa. The acceleration rotation is changed to the deceleration rotation, and at time T3, the decelerating rotation with the maximum capacity of the main shaft 12 at step S5 is executed, and at time T4, the position control of the main shaft 12 at step S7 is executed. At times T1, T2, T3, and T4, the main shaft 12 operates in the same manner as the operation shown in FIG.

  The configuration shown in FIGS. 3 and 4 is based on the premise that the maximum rotational speed V0 of the main shaft 12 is higher than a predetermined speed Vb (for example, the base speed of the servo motor). On the other hand, depending on the configuration of the machine tool, the maximum rotation speed V0 of the spindle 12 may be smaller than the speed Vb. In this case, the times T2 and T3 in FIGS. 3 and 4 are eliminated, and the main shaft 12 operates at a constant acceleration and deceleration from the machining start position to the target screw depth.

  FIG. 5 shows a case where the remaining rotational speed Sr becomes ½ of the total rotational speed S0 before the current speed Vc reaches the maximum rotational speed V0 (<Vb) (the determinations in steps S3 and S4 are both YES). The movement of the main shaft 12 in the case of (case) is shown by a speed-time curve. As shown in the figure, the main shaft 12 performs only the operations at times T1 and T4 in FIG. That is, the spindle 12 rotates at a maximum acceleration A0 with a maximum rotational speed V0 as a target value at a time T1, and changes from acceleration to deceleration at a time A when Sr becomes 1/2 of S0, and remains from a point A at a time T4. The vehicle is decelerated and rotated at the maximum deceleration A0 to the position where the rotation amount Sr = 0. While the main shaft 12 rotates at a reduced speed, the main shaft control unit 18 (positioning operation control unit 38) executes only the position control of the main shaft 12.

  FIG. 6 shows the case where the current speed Vc reaches the maximum rotational speed V0 (<Vb) before the remaining rotational speed Sr becomes 1/2 of the total rotational speed S0 (when the determination in step S3 is NO). The operation of the spindle 12 is shown by a speed-time curve. As shown in the figure, the main shaft 12 performs the operations at times T1 and T4 in FIG. 4 and the operation corresponding to the time T5 in FIG. That is, the spindle 12 rotates at a maximum acceleration A0 with the maximum rotation speed V0 as a target value at time T1, and after reaching the maximum rotation speed V0, the remaining rotation amount Sr becomes equal to the acceleration rotation amount Sa at time T6. The motor rotates at a constant speed V0 until A, and decelerates and rotates at a maximum deceleration A0 from point A to a position where the remaining rotation amount Sr = 0 at time T4. While the main shaft 12 rotates at a constant speed and a reduced speed, the main shaft control unit 18 (positioning operation control unit 38) executes only the position control of the main shaft 12.

  In tapping using a machine tool, it is necessary to perform a return operation for extracting a tool from a work after cutting the prepared hole of the work to a target screw depth. In the above embodiment, when the positioning operation control unit 38 is configured to decelerate and rotate the spindle 12 with the maximum capacity and stop at the target screw depth, the control device 10 performs the above-described target screw depth in the return operation. The same control as the previous cutting operation control can be performed. FIG. 7 shows a return motion control method of the spindle 12 in tapping as an embodiment of a machine tool control method executed by the control device 10. Hereinafter, an example of the control flow of the return operation by the control device 10 will be described with reference to FIG.

  The numerical control unit 16 (spindle command output unit 26) determines that the tap machining has reached the target thread depth in the processing flow of FIG. 2, and then the tap machining program P interpreted by the program interpretation unit 24 in step S10. From the command value, the total return rotation amount S0 ′ and maximum return rotation speed V0 ′ of the spindle 12 from the target screw depth to the return completion position are acquired, and these total return rotation amount S0 ′ and maximum return rotation speed are obtained. V0 'is sent to the spindle control unit 18 as a spindle command CS. The spindle command CS for the return operation also does not include a position command or an acceleration / deceleration command for rotating the spindle 12 to the return completion position. The return completion position may be the same as the machining start position or may be different from the machining start position. When the return completion position is the same as the machining start position, the total return rotation amount S0 ′ is equal to the total rotation amount S0 at the time of cutting, but the maximum return rotation speed V0 ′ does not necessarily coincide with the maximum rotation speed V0 at the time of cutting.

  In step S11, the spindle control unit 18 (initial motion control unit 30, maximum acceleration detection unit 32, remaining rotation amount detection unit 34) performs the following processing. The initial operation control unit 30 accelerates and reversely rotates the spindle 12 from the target screw depth toward the return completion position with the maximum return rotational speed V0 ′ as the target speed, with the maximum capacity utilizing the allowable current of the drive source to the maximum. To return. The maximum acceleration detection unit 32 detects the maximum acceleration A0 ′ of reverse rotation based on the rotation position FBS during acceleration reverse rotation with the maximum capacity. Based on the total return rotation amount S0 ′ and the rotation position FBS, the remaining rotation amount detection unit 34 sequentially detects the remaining return rotation amount Sr ′ of the main shaft 12 from the current position to the return completion position. The main spindle control unit 18 notifies the numerical control unit 16 of the detected return rotation amount Sr ′ each time it is detected.

  Next, in step S12, the spindle control unit 18 (current speed detection unit 36) sequentially detects the current speed Vc ′ of reverse rotation based on the rotation position FBS during acceleration reverse rotation at the maximum capacity, and each time it is detected, It is determined whether or not the speed Vc ′ has reached the maximum return rotational speed V0 ′. If Vc ′ has not reached V0 ′, in step S13, the spindle control unit 18 determines whether or not the remaining return rotation amount Sr ′ is less than or equal to ½ of the total return rotation amount S0 ′. If Sr ′ is equal to or less than ½ of S0 ′, in step S14, the spindle control unit 18 returns the spindle 12 by decelerating and reversely rotating the spindle 12 with the maximum capacity using the allowable current of the drive source to the maximum. Continue operation. If Sr ′ is not less than 1/2 of S0 ′, the process returns to step S12.

Next, in step S15, the spindle control unit 18 (positioning operation control unit 38) determines that the absolute value | Sr ′ | of the remaining return rotation amount Sr ′ at the current position of the spindle 12 is | Sr ′ | = Vb ² / | A0. It is determined whether or not ′ | / 120 is satisfied. When | Sr ′ | = Vb ² / | A0 ′ | / 120 is satisfied, the spindle control unit 18 (positioning operation control unit 38) decelerates and rotates the spindle 12 at the maximum deceleration A0 ′ in step S16. Then, a command for stopping at the point of Sr ′ = 0 (that is, the return completion position) is created, and the position of the spindle 12 is controlled by this command. If | Sr ′ | = Vb ² / | A0 ′ | / 120 is not satisfied, the determination is repeated until this equation is satisfied. In accordance with a command from the main spindle control unit 18 (positioning operation control unit 38), the main spindle 12 decelerates and reversely rotates at the maximum deceleration A0 'toward the return completion position, and returns to Sr' = 0. Stop at the moment.

  If it is determined in step S12 that the current speed Vc ′ has reached the maximum return rotational speed V0 ′, the spindle control unit 18 in step S17 determines the main spindle 12 when the maximum return rotational speed V0 ′ has been reached. The rotation amount from the target screw depth (that is, the rotation position FBS) is stored as the rotation amount Sa ′ during acceleration of the return operation. In step S18, the spindle control unit 18 determines whether or not the remaining return rotation amount Sr ′ is equal to or less than the acceleration rotation amount Sa ′. If Sr ′ is equal to or lower than Sa ′, the process proceeds to step S14, and then step S15 and step S16 are executed to perform the return operation to the return completion position. If Sr ′ is not less than or equal to Sa ′, the determination is repeated until Sr ′ becomes less than or equal to Sa ′.

  The return operation of the main shaft 12 described above can be represented by a speed-time curve similar to the cutting operation shown in FIG. 3 or FIG. When the total return rotation amount S0 ′ and the maximum return rotation speed V0 ′ are the same as the total rotation amount S0 and the maximum rotation speed V0 at the time of cutting, the cutting operation and the return operation have substantially the same speed-time curve. Show. On the other hand, when the total return rotation amount S0 ′ and the maximum return rotation speed V0 ′ are different from the total rotation amount S0 and the maximum rotation speed V0 at the time of cutting, the cutting operation and the return operation do not necessarily show the same speed-time curve.

  While the main shaft control unit 18 controls the reverse rotation operation from the target screw depth of the main shaft 12 to the return completion position, the feed shaft control unit 22 uses the rotation position FBS of the main shaft 12 to move the feed shaft 14 to the main shaft 12. A reverse feed operation is performed by controlling to follow the operation. The numerical controller 16 monitors the return rotation amount Sr ′ notified from the spindle control unit 18 while the spindle control unit 18 executes the processes of Steps S10 to S18. When the value is equal to or smaller than a predetermined value of 2 (minimum value close to zero), it is determined that the return operation is completed and the tool is pulled out from the workpiece.

  When the control device 10 according to the above embodiment causes the spindle 12 to perform a cutting operation from the machining start position to the target screw depth, the numerical control unit 16 controls the spindle control unit 18 with the total rotation amount S0 of the spindle 12. Only the maximum rotation speed V0 is notified as the spindle command CS, and the spindle control unit 18 accelerates the spindle 12 with the maximum output using the maximum allowable current for the maximum rotation speed V0 in accordance with the spindle command CS. , And based on the maximum acceleration A0 and the remaining rotation amount Sr of the main shaft 12 and the current speed Vc that are sequentially detected, the cutting operation to the target screw depth is performed in the shortest time while the main shaft 12 is decelerated at the maximum deceleration A0. It is constituted so that the target screw depth can be reached by continuously executing. Therefore, according to the control device 10, it is not necessary to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 with respect to the numerical controller 12, and the spindle 12 can be configured with a simpler configuration. Acceleration / deceleration control that maximizes the acceleration capability of the tapping process can be performed to shorten the tapping cycle time.

  Further, in the control device 10 according to the above embodiment, when the spindle 12 performs the return operation from the target screw depth to the return completion position, the numerical controller 16 makes the total return of the spindle 12 to the spindle controller 18. Only the rotation amount S0 ′ and the maximum return rotation speed V0 ′ are notified as the spindle command CS, and the spindle control unit 18 follows the spindle command CS and outputs the maximum output using the maximum allowable current with the maximum return rotation speed V0 ′ as a target. The main shaft 12 is accelerated to perform a return operation, and the main shaft 12 is moved to the maximum deceleration A0 'based on the maximum acceleration A0' during this time and the remaining rotational speed Sr 'of the main shaft 12 and the current speed Vc' which are sequentially detected. The return operation until the return completion position is continuously executed in the shortest time while decelerating at, and stopped at the return completion position. Therefore, according to the control device 10, it is not necessary to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 with respect to the numerical controller 12, and the spindle 12 can be configured with a simpler configuration. Acceleration / deceleration control that maximizes the acceleration capability of the tapping process can be performed to shorten the tapping cycle time.

  The configuration of the control device 10 according to the above embodiment can be described as a machine tool control method for controlling the synchronous operation of the main shaft 12 and the feed shaft 14. In this control method, the control device 10 acquires the total rotation amount S0 and the maximum rotation speed V0 of the spindle 12 from the machining start position to the target screw depth from the tapping program P, and sets the maximum rotation speed V0 to the target. As a value, the spindle 12 is accelerated and rotated at the maximum capacity from the machining start position toward the target screw depth, and the maximum acceleration A0 is detected based on the rotational position feedback value FBS of the spindle 12 during the acceleration rotation at the maximum capacity, and the total rotation Based on the amount S0 and the rotational position feedback value FBS, the remaining rotational amount Sr of the main shaft 12 from the current position to the target screw depth is detected, and based on the rotational position feedback value FBS, the current speed Vc of the main shaft 12 is detected. After the acceleration rotation at the maximum capacity, the spindle 12 is decelerated and rotated at the maximum capacity based on the maximum acceleration A0, the remaining rotation amount Sr, and the current speed Vc, and the target screw depth It is intended to reach the. At this time, the spindle 12 can be configured to rotate at a reduced speed with the maximum capacity and to stop at the target screw depth.

  In the above control method, the control device 10 acquires the total return rotation amount S0 ′ and the maximum return rotation speed V0 ′ of the main shaft 12 from the target screw depth to the return completion position from the tapping program P, and the maximum Based on the rotational position feedback value FBS of the main shaft 12 during the reverse rotation at the maximum capacity, the main shaft 12 is accelerated and reverse rotated at the maximum capacity from the target screw depth toward the return completion position with the return rotational speed V0 ′ as the target value. Maximum reverse rotation acceleration A0 ′ is detected, and based on total return rotation amount S0 ′ and rotational position feedback value FBS, residual rotation amount Sr ′ of spindle 12 from the current position to the return completion position is detected, Based on the rotational position feedback value FBS, the current speed Vc ′ of the reverse rotation of the main shaft 12 is detected. After the acceleration reverse rotation at the maximum capacity, the maximum acceleration A0 ′ of the reverse rotation and the remaining rotation amount Based on the r 'and the reverse rotation of the current speed Vc', it is intended to stop the main shaft 12 at the end position return together to decelerate reverse rotation at full capacity.

  In tapping using a machine tool, it is desirable that the control device continuously recognizes the rotational position of the main shaft and the feed position of the feed shaft during tapping. FIG. 8 is a functional block diagram showing the configuration of the control device 40 according to a modified example to which the position recognition function of the main shaft and the feed shaft is added. The control device 40 has the same configuration as the control device 10 of FIG. 1 except that a position recognition function is added. Corresponding components are denoted by common reference numerals, and detailed description thereof is omitted.

  The control device 40 includes a numerical control unit 16 that generates a spindle command CS and a feed axis command CF based on the tap machining program P, a spindle control unit 18 that controls the rotation operation of the spindle 12 according to the spindle command CS, and the rotation of the spindle 12. The rotation detection unit 20 that detects the position, the feed axis control unit 22 that controls the feed operation of the feed shaft 14 based on the rotation position detected by the rotation detection unit 20 according to the feed axis command CF, and the feed position of the feed shaft 14 And a feed detection unit 42 for detecting. The feed axis command output unit 28 of the numerical control unit 16 determines the total feed amount of the feed shaft 14 corresponding to the target screw depth from the command value of the tap machining program P interpreted by the program interpretation unit 24 prior to the start of tapping. D0 (mm) and screw pitch P (mm / rev) are acquired, and the total feed amount D0 and screw pitch P are sent to the feed axis control unit 22 as a feed axis command CF. Thus, the feed axis command CF does not include a position command or acceleration / deceleration command for feeding the feed shaft 14 to the target screw depth.

  The feed axis control unit 22 includes a rotation position FBS of the main shaft 12 detected by the rotation detection unit 20, a screw pitch P, and a feed position of the feed shaft 14 detected by the feed detection unit 42 (feedback value; hereinafter referred to as a feed position FBF). ) Based on the feed operation control unit 44 for controlling the feed operation of the feed shaft 14, and the remaining feed of the feed shaft 14 from the current position to the target screw depth based on the total feed amount D0 and the feed position FBF. A remaining feed amount detection unit 46 for detecting the amount Dr. The feed detector 42 can acquire the feed position FBF from the output of a position detector (not shown) such as an encoder that detects the operating position of the drive device of the feed shaft 14.

  The remaining rotation amount detection unit 34 of the spindle control unit 18 sequentially detects the remaining rotation amount Sr from the current position of the spindle 12 while the spindle 12 is being cut from the machining start position to the target screw depth. The numerical value control unit 16 is notified of the rotation amount Sr. The remaining feed amount detection unit 46 of the feed shaft control unit 22 sequentially detects the remaining feed amount Dr from the current position of the feed shaft 14 while the feed shaft 14 is fed from the machining start position to the target screw depth. Each time the remaining feed amount Dr is notified to the numerical control unit 16. Further, the feed axis control unit 22 notifies the numerical control unit 16 of the initial position Di (feed position FBF) of the feed shaft 14 at the start of machining.

  The numerical control unit 16 includes a position recognition unit 48 that recognizes the current position of the main shaft 12 based on the remaining rotation amount Sr and recognizes the current position of the feed shaft 14 based on the remaining feed amount Dr. The position recognition unit 48 uses the total rotation amount S0 of the spindle 12 acquired from the tap machining program P and the remaining rotation amount Sr of the spindle 12 notified from the spindle control unit 18 to determine the current position of the spindle 12 (S0). -Sr). The position recognition unit 48 uses the total feed amount D0 of the feed shaft 14 acquired from the tap machining program P, the remaining feed amount Dr of the feed shaft 14 and the initial position Di notified from the feed shaft control unit 22, and The current position of the feed shaft 14 is recognized as (D0−Dr + Di).

  In the control device 40 having the above configuration, the spindle command CS generated by the numerical control unit 16 does not include the position command or acceleration / deceleration command of the spindle 12, and the feed axis command CF generated by the numerical control unit 16 includes the feed axis 14 Even in a configuration that does not include a position command or an acceleration / deceleration command, the position recognition unit 48 of the numerical control unit 16 can recognize the current positions of the spindle 12 and the feed shaft 14. Therefore, according to the control device 40, the numerical control unit 16 which is a higher-order controller of the main shaft control unit 18 and the feed shaft control unit 22 that performs feedback control is configured to change the operation states of the main shaft 12 and the feed shaft 14 while tapping is being performed. Therefore, the reliability of tapping control can be improved.

  In the control device 40, the position recognition unit 48 of the numerical control unit 16 can similarly recognize the current positions of the main shaft 12 and the feed shaft 14 while controlling the return operation of the tapping process. In this case, as described above, when the numerical control unit 16 determines that the tapping has reached the target thread depth, the feed axis command output unit 28 instructs the tapping program P interpreted by the program interpretation unit 24. From the value, the total return feed amount D0 '(mm) and the screw pitch P (mm / rev) of the feed shaft 14 corresponding to the target screw depth are obtained, and the total return feed amount D0' and the screw pitch P are obtained. Is sent to the feed axis control unit 22 as a feed axis command CF. Usually, the total return feed amount D0 ′ coincides with the total feed amount D0.

  The feed operation control unit 44 of the feed shaft control unit 22 performs a return feed operation of the feed shaft 14 based on the rotational position FBS of the return operation of the main shaft 12, the screw pitch P, and the feed position FBF of the return operation of the feed shaft 14. To control. The remaining feed amount detection unit 46 of the feed shaft control unit 22 detects the remaining return feed amount Dr ′ of the feed shaft 14 from the current position to the return completion position based on the total return feed amount D0 ′ and the feed position FBF. To do. The remaining rotation amount detection unit 34 of the main shaft control unit 18 sequentially detects the remaining return rotation amount Sr ′ from the current position of the main shaft 12 while the main shaft 12 is returned from the target screw depth to the return completion position. Each time, the numerical control unit 16 is notified of the remaining return rotation amount Sr ′. The remaining feed amount detection unit 46 of the feed shaft control unit 22 sequentially detects the remaining return feed amount Dr ′ from the current position of the feed shaft 14 while the feed shaft 14 is being fed back from the target screw depth to the return completion position. Then, each time the detection is made, the numerical controller 16 is notified of the remaining return feed amount Dr ′. Further, the feed axis control unit 22 notifies the numerical control unit 16 of the initial position Di ′ (feed position FBF) of the feed shaft 14 at the start of the return operation. The position recognition unit 48 of the numerical control unit 16 recognizes the current position (S0′-Sr ′) of the main shaft 12 by using the total return rotation amount S0 ′ and the remaining return rotation amount Sr ′ of the main shaft 12, and feed axis. The current position (D0′−Dr ′ + Di ′) of the feed shaft 14 is recognized using the total return feed amount D0 ′, the remaining return feed amount Dr ′, and the initial position Di ′.

  In tapping using a machine tool, it is desirable for the control device to continuously recognize the synchronization error between the spindle and the feed axis during tapping. FIG. 9 is a functional block diagram showing the configuration of a control device 50 according to a modification in which a function of recognizing the synchronization error between the main shaft and the feed shaft is added. The control device 50 has the same configuration as the control device 10 of FIG. 1 except that a synchronization error recognition function is added. Corresponding components are denoted by common reference numerals, and detailed description thereof is omitted.

  The control device 50 includes a numerical control unit 16 that generates a spindle command CS and a feed axis command CF based on the tap machining program P, a spindle control unit 18 that controls the rotation operation of the spindle 12 according to the spindle command CS, and the rotation of the spindle 12. The rotation detection unit 20 that detects the position, the feed axis control unit 22 that controls the feed operation of the feed shaft 14 based on the rotation position detected by the rotation detection unit 20 according to the feed axis command CF, and the feed position of the feed shaft 14 And a feed detection unit 42 for detecting. The feed axis command output unit 28 of the numerical control unit 16 determines the total feed amount of the feed shaft 14 corresponding to the target screw depth from the command value of the tap machining program P interpreted by the program interpretation unit 24 prior to the start of tapping. D0 (mm) and screw pitch P (mm / rev) are acquired, and the total feed amount D0 and screw pitch P are sent to the feed axis control unit 22 as a feed axis command CF. Thus, the feed axis command CF does not include a position command or acceleration / deceleration command for feeding the feed shaft 14 to the target screw depth.

  The feed axis control unit 22 includes a rotation position FBS of the main shaft 12 detected by the rotation detection unit 20, a screw pitch P, and a feed position of the feed shaft 14 detected by the feed detection unit 42 (feedback value; hereinafter referred to as a feed position FBF). ) Based on the feed operation control unit 44 for controlling the feed operation of the feed shaft 14, and the remaining feed of the feed shaft 14 from the current position to the target screw depth based on the total feed amount D0 and the feed position FBF. A remaining feed amount detection unit 46 for detecting the amount Dr. The remaining rotation amount detection unit 34 of the spindle control unit 18 sequentially detects the remaining rotation amount Sr from the current position of the spindle 12 while the spindle 12 is being cut from the machining start position to the target screw depth. The numerical value control unit 16 is notified of the rotation amount Sr. The remaining feed amount detection unit 46 of the feed shaft control unit 22 sequentially detects the remaining feed amount Dr from the current position of the feed shaft 14 while the feed shaft 14 is fed from the machining start position to the target screw depth. Each time the remaining feed amount Dr is notified to the numerical control unit 16.

The numerical control unit 16 includes a synchronization error calculation unit 52 that calculates the synchronization error of the synchronous operation of the main shaft 12 and the feed shaft 14 based on the remaining rotation amount Sr, the remaining feed amount Dr, and the screw pitch P. The synchronization error calculation unit 52 includes a remaining rotation amount Sr (rev) of the main shaft 12 notified from the main shaft control unit 18, a remaining feed amount Dr (mm) of the feed shaft 14 notified from the feed shaft control unit 22, and a screw. Using the pitch P (mm / rev), the synchronization error E between the main shaft 12 and the feed shaft 14 is calculated by the following equation.
When calculating the synchronization error E by converting it into the amount of rotation of the spindle 12:
E (rev) = Sr−Dr / P
When calculating the synchronization error E by converting it into the feed amount of the feed shaft 14:
E (mm) = Sr × P-Dr

  In the control device 50 having the above configuration, even if the numerical control unit 16 does not perform feedback control of the main shaft 12 and the feed shaft 14, the synchronization error calculation unit 52 of the numerical control unit 16 includes the main shaft 12 and the feed shaft 14. And the synchronization error E can be obtained. Therefore, according to the control device 50, the numerical control unit 16 which is a higher-order controller of the main spindle control unit 18 and the feed axis control unit 22 that performs feedback control, detects the synchronization error E between the main shaft 12 and the feed axis 14 by tapping. It is possible to always grasp or manage during execution, thereby improving the reliability of tapping control.

  The numerical control unit 16 of the control device 50 can include a display control unit 56 that causes the display device 54 to display the synchronization error E obtained by the synchronization error calculation unit 52. According to this configuration, the operator can sequentially check the synchronization error E while the machine tool is performing the tap machining, and thus, it is possible to quickly execute a countermeasure according to the synchronization error E. .

  In the control device 50, the synchronization error calculation unit 52 of the numerical control unit 16 can similarly calculate the synchronization error E between the main shaft 12 and the feed shaft 14 while controlling the return operation of the tapping process. In this case, as described above, when the numerical control unit 16 determines that the tapping has reached the target thread depth, the feed axis command output unit 28 instructs the tapping program P interpreted by the program interpretation unit 24. From the value, the total return feed amount D0 '(mm) and the screw pitch P (mm / rev) of the feed shaft 14 corresponding to the target screw depth are obtained, and the total return feed amount D0' and the screw pitch P are obtained. Is sent to the feed axis control unit 22 as a feed axis command CF. Usually, the total return feed amount D0 ′ coincides with the total feed amount D0.

  The feed operation control unit 44 of the feed shaft control unit 22 performs a return feed operation of the feed shaft 14 based on the rotational position FBS of the return operation of the main shaft 12, the screw pitch P, and the feed position FBF of the return operation of the feed shaft 14. To control. The remaining feed amount detection unit 46 of the feed shaft control unit 22 detects the remaining return feed amount Dr ′ of the feed shaft 14 from the current position to the return completion position based on the total return feed amount D0 ′ and the feed position FBF. To do. The remaining rotation amount detection unit 34 of the main shaft control unit 18 sequentially detects the remaining return rotation amount Sr ′ from the current position of the main shaft 12 while the main shaft 12 is returned from the target screw depth to the return completion position. Each time, the numerical control unit 16 is notified of the remaining return rotation amount Sr ′. The remaining feed amount detection unit 46 of the feed shaft control unit 22 sequentially detects the remaining return feed amount Dr ′ from the current position of the feed shaft 14 while the feed shaft 14 is being fed back from the target screw depth to the return completion position. Then, each time the detection is made, the numerical controller 16 is notified of the remaining return feed amount Dr ′. The synchronization error calculation unit 52 of the numerical control unit 16 synchronizes the main shaft 12 and the feed shaft 14 by using the residual return rotation amount Sr ′ of the main shaft 12, the residual return feed amount Dr ′ of the feed shaft 14, and the screw pitch P. The error E (E = Sr′−Dr ′ / P or E = Sr ′ × P−Dr ′) is calculated.

  FIG. 10 shows a cutting and return motion control method of the spindle 12 in tapping as another embodiment of the machine tool control method that can be executed by the control device 10 of FIG. 11 and 12 show two examples of the operation of the main shaft 12 in the embodiment of FIG. Hereinafter, with reference to FIG. 1, FIG. 2, FIG. 7 and FIG. 10 to FIG. 12, a machine tool control method (tapping cutting and return operation control method) according to another embodiment, and other methods for executing the method A configuration of the control device 10 according to the embodiment will be described. Note that the control device 40 (FIG. 8) and the control device 50 (FIG. 9) according to the above-described modification can also execute the tap cutting and return operation control method described below.

  In general, in the embodiment shown in FIGS. 10 to 12, the control device 10 taps shown in FIG. 2 until the spindle 12 reaches the target screw depth (rotation position) from the machining start position (rotation position). Steps similar to the cutting operation control method for machining are executed to control the cutting operation of the spindle 12. The spindle control unit 18 (positioning operation control unit 38) of the control device 10 does not stop the spindle 12 at the target screw depth when the spindle 12 reaches the target screw depth (that is, zero acceleration). The main shaft 12 is accelerated and reversely rotated to a predetermined rotational position with the same reverse acceleration A0 (negative value) as the maximum deceleration A0 (negative value) in the deceleration rotation with the maximum capacity. Composed. After the spindle 12 is accelerated and reversely rotated to a predetermined rotational position, the control device 10 executes the same steps as the tap machining return operation control method shown in FIG. 7 to control the return operation of the spindle 12. . The configuration of this embodiment will be described in detail below, but the description of the components corresponding to the components of FIGS. 2 and 7 will be omitted as appropriate.

  As shown in FIG. 10, the control device 10 first executes steps S1 to S6, S8, and S9 shown in FIG. 2 (step U1). Referring now to FIG. 11, when the remaining speed Sr becomes 1/2 of the total speed S0 before the current speed Vc reaches the maximum speed V0 during the cutting operation (steps S3 and S4 in FIG. 2). The operation of the main shaft 12 is shown by a speed-time curve. The operation of the main shaft 12 at times T1, T2, T3 and T4 in the speed-time curve of FIG. 11 corresponds to the operation of the main shaft 12 at times T1, T2, T3 and T4 in the speed-time curve of FIG. In other words, as shown in FIG. 11, at the time T1 and T2, the maximum capacity acceleration rotation of the main shaft 12 is executed, and the operation of the main shaft 12 is performed at the time A when the remaining rotation amount Sr becomes 1/2 of the total rotation amount S0. Changes from accelerated rotation to decelerated rotation, and at time T3, the decelerated rotation with the maximum capacity of the main shaft 12 is executed, and at time T4, position control of the main shaft 12 is executed.

When the control device 10 executes Step U1 (Steps S1, S2, S3, S4, S5, and S6 in FIG. 2), the spindle 12 is changed to the time shown in FIG. 3 at times T1, T2, T3, and T4 shown in FIG. The operation is similar to the operation at the times T1, T2, T3, and T4 shown. However, the main shaft control unit 18 (positioning operation control unit 38) determines that the absolute value | Sr | of the remaining rotation amount at the current position of the main shaft 12 is | Sr | = Vb ² / | A0 | / 120 in step S6 of FIG. Is satisfied (that is, the rotational position of the main shaft 12 has reached the point B), the main shaft 12 is decelerated and rotated at the maximum deceleration A0 in step U2 (FIG. 10). That is, after reaching the target screw depth), a command for accelerating and reversely rotating the spindle 12 to a predetermined rotational position (corresponding to the point C in FIG. 11) with the same reverse rotational acceleration A0 as the maximum deceleration A0. And the position of the spindle 12 is controlled by this command.

  As shown in FIG. 11, the spindle 12 performs a cutting operation while rotating at a reduced speed with a maximum deceleration A0 from the point B toward the target screw depth in accordance with a command from the spindle control unit 18 (positioning operation control unit 38). Then, when Sr = 0, the target screw depth is reached (time T4). At the moment when the target screw depth is reached, the current speed Vc of the spindle 12 becomes zero, but the spindle 12 maintains the maximum deceleration A0 according to a command from the spindle control unit 18 (positioning operation control unit 38). A reverse operation from the target screw depth toward the point C is performed over time T7 by acceleration reverse rotation that generates reverse rotation acceleration A0 and gradually increases the current speed Vc (negative value). As described above, at the time T4 from the point B to reach the target screw depth and the time T7 from the target screw depth to the point C, the spindle control unit 18 controls the position of the spindle 12 (step U2). And continuously operating at a constant acceleration A0 (constant acceleration speed command is illustrated by a broken line). The spindle 12 has a current speed Vc of zero at the target screw depth, but this is instantaneous and does not stop at the target screw depth.

The position of the point C of the main shaft 12 can be arbitrarily set. For example, as shown in FIG. 11, the same position as the point B where the deceleration rotation at the maximum deceleration A0 is started during the cutting operation can be set as the point C. In this case, the point C is a position reversely rotated by a rotation amount corresponding to | Sr | = Vb ² / | A0 | / 120 from the target screw depth. According to this configuration, as shown in FIG. 11, the cutting operation (time T1 to T4) of the main shaft 12 from the start of machining through the point B to the target screw depth and the point C from the target screw depth. The return operation (time T7 to T10) of the main shaft 12 until reaching the return completion position can be represented by substantially the same speed-time curve except that the sign of the speed is reversed. That is, the main shaft 12 rotates at the constant acceleration A0 at the same time as the acceleration rotation at the constant maximum acceleration A0 at the time T1, at the time T7. Strictly speaking, however, as a control characteristic, the maximum deceleration A0 (time T4) at the time of decelerating rotation of the maximum capacity by the position control is compared with the maximum acceleration A0 (time T1) of the maximum capacity by the speed control. As a result, the reverse rotation acceleration A0 at time T7 tends to be slightly lower than the maximum acceleration A0 at time T1.

  While the main shaft control unit 18 controls the rotation operation from the machining start position of the main shaft 12 to the target screw depth, the feed shaft control unit 22 uses the rotation position FBS of the main shaft 12 to change the feed shaft 14 to the operation of the main shaft 12. The feed operation is performed under control to follow. The numerical control unit 16 monitors the remaining rotation amount Sr notified from the spindle control unit 18 while the spindle control unit 18 executes the processes of Step U1 and Step U2, and the remaining rotation amount Sr is a first predetermined value. When the value becomes (minimum value close to zero) or less, it is determined that tapping has reached the target thread depth. Then, the numerical control unit 16 (spindle command output unit 26) determines that the tap machining has reached the target thread depth, and then in parallel with step U2, the tap machining program interpreted by the program interpretation unit 24 in step U3. From the command value of P, the total return rotation amount S0 ′ and the maximum return rotation speed V0 ′ of the spindle 12 from the target screw depth to the return completion position are obtained, and these total return rotation amount S0 ′ and the maximum return The rotation speed V0 ′ is sent to the spindle control unit 18 as a spindle command CS.

  After the main shaft 12 reaches the predetermined rotational position (point C), in step U4, the main shaft control unit 18 (initial operation control unit 30) sets the maximum return rotational speed V0 ′ as the target speed and the predetermined rotational position (point C). ) To the return completion position, the spindle 12 is accelerated and reverse-rotated with the maximum capacity utilizing the maximum allowable current of the drive source, and the return operation is executed. The spindle control unit 18 (remaining rotation amount detection unit 34) sequentially calculates the remaining return rotation amount Sr 'of the main shaft 12 from the current position to the return completion position based on the total return rotation amount S0' and the rotation position FBS. To detect. The main spindle control unit 18 notifies the numerical control unit 16 of the detected return rotation amount Sr ′ each time it is detected.

  Next, the control apparatus 10 performs step S12-S18 shown in FIG. 7 (step U5). In the operation example of FIG. 11, the spindle control unit 18 (current speed detection unit 36) sequentially detects the current speed Vc ′ of reverse rotation based on the rotational position FBS during acceleration reverse rotation (time T8) at the maximum capacity, Each time it is detected, it is determined whether or not the current speed Vc ′ has reached the maximum return rotational speed V0 ′ (step S12). When Vc ′ has not reached V0 ′, the spindle control unit 18 determines whether or not the remaining return rotation amount Sr ′ is equal to or less than ½ of the total return rotation amount S0 ′ (step S13). When Sr ′ is less than or equal to ½ of S0 ′, the main spindle control unit 18 continuously performs the return operation by rotating the main spindle 12 by decelerating and reversely rotating with the maximum capacity utilizing the allowable current of the drive source. (Step S14).

  In the example shown in FIG. 11, since the current speed of reverse rotation exceeds Vb (negative value) after reaching the predetermined rotational position (point C), the main shaft 12 is, for example, a servo in acceleration reverse rotation with the maximum capacity. Due to the characteristics of the motor, the reverse rotation acceleration of the main shaft 12 gradually decreases from A0 (time T8). At the time point D when the remaining return rotation amount Sr ′ becomes 1/2 of the total return rotation amount S0 ′ (that is, the rotation amount from the target screw depth becomes 1/2 of the total rotation amount S0 ′), the main shaft 12 The operation is changed from the reverse acceleration to the reverse deceleration, and at time T9, the reverse reverse rotation with the maximum capacity of the spindle 12 is executed. As described above, at time T8 to T9, the spindle control unit 18 controls the speed of the spindle 12 (a stepped speed command is exemplified by a broken line).

Next, the spindle control unit 18 (positioning operation control unit 38) determines that the absolute value | Sr ′ | of the remaining return rotation amount Sr ′ at the current position of the spindle 12 is | Sr ′ | = Vb ² / | A0 ′ | / 120. (That is, whether or not the rotational position of the spindle 12 has reached point E (FIG. 11)) is determined (step S15). When | Sr ′ | = Vb ² / | A0 ′ | / 120 is satisfied, the spindle control unit 18 (positioning operation control unit 38) reduces the spindle 12 to the maximum deceleration A0 ′ (acceleration of reverse rotation A0 at time T7). A command for decelerating and reversely rotating at a point of Sr ′ = 0 (that is, a return completion position) is generated, and the position of the spindle 12 is controlled by this command (step S16). In accordance with a command from the main spindle control unit 18 (positioning operation control unit 38), the main spindle 12 decelerates and reversely rotates at the maximum deceleration A0 'toward the return completion position, and returns to Sr' = 0. Stop at the moment. As described above, at the time T10 (FIG. 11) from the point E to the return completion position, the spindle control unit 18 controls the position of the spindle 12 (constant acceleration speed command is exemplified by a broken line).

  While the main shaft control unit 18 controls the reverse rotation operation from the target screw depth of the main shaft 12 to the return completion position, the feed shaft control unit 22 uses the rotation position FBS of the main shaft 12 to move the feed shaft 14 to the main shaft 12. A reverse feed operation is performed by controlling to follow the operation. The numerical controller 16 monitors the return rotation amount Sr ′ notified from the spindle control unit 18 while the spindle control unit 18 executes the processes of Step U3 to Step U5. When the value is equal to or smaller than a predetermined value of 2 (minimum value close to zero), it is determined that the return operation is completed and the tool is pulled out from the workpiece.

  FIG. 12 shows a case where the current speed Vc reaches the maximum rotational speed V0 before the remaining rotational speed Sr becomes 1/2 of the total rotational speed S0 during the cutting operation in Step U1 of FIG. 10 (Step S3 of FIG. 2). The operation of the spindle 12 when the determination of NO is NO) is shown by a speed-time curve. The operation of the main shaft 12 at the times T1, T2, T3, T4 and T5 in the speed-time curve of FIG. 12 is the operation of the main shaft 12 at the times T1, T2, T3, T4 and T5 in the speed-time curve of FIG. Corresponding to That is, as shown in FIG. 12, at the times T1 and T2, the maximum speed acceleration rotation of the main shaft 12 is executed, the current speed Vc of the main shaft 12 reaches the maximum rotation speed V0, and then the constant speed over the time T5. At time point A when the main shaft 12 is rotated at V0 and tapping is continued, and the remaining rotation amount Sr becomes equal to the rotation amount Sa during acceleration, the operation of the main shaft 12 changes from acceleration rotation to deceleration rotation. Deceleration rotation with the maximum capacity of 12 is executed, and position control of the spindle 12 is executed at time T4.

When the control device 10 executes step U1 (steps S1, S2, S3, S8, S9, S5, and S6 in FIG. 2), the spindle 12 is in the time T1, T2, T3, T4, and T5 shown in FIG. The operation is similar to the operation at times T1, T2, T3, T4, and T5 shown in FIG. However, the main shaft control unit 18 (positioning operation control unit 38) determines that the absolute value | Sr | of the remaining rotation amount at the current position of the main shaft 12 is | Sr | = Vb ² / | A0 | / 120 in step S6 of FIG. Is satisfied (that is, the rotational position of the main shaft 12 has reached the point B), the main shaft 12 is decelerated and rotated at the maximum deceleration A0 in step U2 (FIG. 10). That is, after reaching the target screw depth), a command for accelerating and reversely rotating the spindle 12 to a predetermined rotational position (corresponding to point C in FIG. 12) at the same reverse rotational acceleration A0 as the maximum deceleration A0. And the position of the spindle 12 is controlled by this command.

  As shown in FIG. 12, the spindle 12 performs a cutting operation while rotating at a reduced speed with a maximum deceleration A0 from the point B toward the target screw depth in accordance with a command from the spindle control unit 18 (positioning operation control unit 38). Then, when Sr = 0, the target screw depth is reached (time T4). At the moment when the target screw depth is reached, the current speed Vc of the spindle 12 becomes zero, but the spindle 12 maintains the maximum deceleration A0 according to a command from the spindle control unit 18 (positioning operation control unit 38). A reverse operation from the target screw depth toward the point C is performed over time T7 by acceleration reverse rotation that generates reverse rotation acceleration A0 and gradually increases the current speed Vc (negative value). As described above, at the time T4 from the point B to reach the target screw depth and the time T7 from the target screw depth to the point C, the spindle control unit 18 controls the position of the spindle 12 (step U2). And continuously operating at a constant acceleration A0 (constant acceleration speed command is illustrated by a broken line). The operation of the main shaft 12 at times T4 and T7 is the same as the operation of the main shaft 12 at times T4 and T7 shown in FIG.

  Next, the control device 10 executes Steps U3 and U4 in FIG. In step U5, as shown in FIG. 12, at time T8, acceleration reverse rotation of the maximum capacity of the main shaft 12 is executed, and the current speed Vc (negative value) of the main shaft 12 becomes the maximum rotational speed V0 (negative value). After that, at a time D when the main shaft 12 reversely rotates at a constant speed V0 and continues the return operation over time T11, and the remaining return rotation amount Sr ′ becomes equal to the acceleration rotation amount Sa. The operation changes from acceleration rotation to deceleration rotation, and at time T9, deceleration reverse rotation with the maximum capacity of the spindle 12 is executed, and at time T10, position control to the return completion position of the spindle 12 is executed. The operation of the main shaft 12 at times T8, T9, and T10 is the same as the operation of the main shaft 12 at times T8, T9, and T10 shown in FIG.

  While the main shaft control unit 18 controls the reverse rotation operation from the target screw depth of the main shaft 12 to the return completion position, the feed shaft control unit 22 uses the rotation position FBS of the main shaft 12 to move the feed shaft 14 to the main shaft 12. A reverse feed operation is performed by controlling to follow the operation. The numerical controller 16 monitors the return rotation amount Sr ′ notified from the spindle control unit 18 while the spindle control unit 18 executes the processes of Step U3 to Step U5. When the value is equal to or smaller than a predetermined value of 2 (minimum value close to zero), it is determined that the return operation is completed and the tool is pulled out from the workpiece.

  The control device 10 according to the embodiment shown in FIGS. 10 to 12 performs the cutting operation from the machining start position to the target screw depth on the main shaft 12 in the same manner as the control devices 10, 40 and 50 according to the embodiment of FIGS. When performing, the numerical control unit 16 notifies only the total rotation amount S0 and the maximum rotation speed V0 of the main shaft 12 to the main shaft control unit 18 as the main shaft command CS, and the main shaft control unit 18 follows the main shaft command CS. The spindle 12 is accelerated with the maximum output using the maximum allowable current with the maximum rotational speed V0 as a target, and the cutting operation is executed. At the same time, the maximum acceleration A0 and the remaining rotational amount Sr of the spindle 12 and the current speed detected sequentially. Based on Vc, the spindle 12 is decelerated at the maximum deceleration A0, and the cutting operation up to the target screw depth is continuously executed in the shortest time to reach the target screw depth. Therefore, according to the control device 10, it is not necessary to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 with respect to the numerical controller 12, and the spindle 12 can be configured with a simpler configuration. Acceleration / deceleration control that maximizes the acceleration capability of the tapping process can be performed to shorten the tapping cycle time.

  When the control device 10 according to the embodiment shown in FIGS. 10 to 12 causes the main shaft 12 to perform the return operation from the target screw depth to the return completion position, first, the main shaft 12 is moved to the target screw at the end of the cutting operation. Without stopping at the depth (that is, without making the acceleration zero), the spindle 12 is moved to the predetermined rotational position with the same reverse rotation acceleration A0 (negative value) as the maximum deceleration A0 (negative value). It is configured to accelerate and reversely rotate under control. This configuration eliminates the change in acceleration when the operation of the spindle 12 is switched from the cutting operation to the return operation. Therefore, the change is caused by an impact on the mechanical structure that can occur in the spindle 12 due to the change in acceleration or a change in acceleration. Thus, an increase in synchronization error that may occur between the main shaft 12 and the feed shaft 14 can be avoided. In the returning operation of the main shaft 12 shown in FIG. 7, after the main shaft 12 is temporarily stopped at the target screw depth at the end of the cutting operation (that is, the acceleration is made zero), the main shaft 12 is accelerated from the target screw depth with the maximum output. In order to perform reverse rotation speed control, the constant acceleration speed command (position control) is switched to a step speed command (speed control) when the spindle 12 is reversed, and static friction becomes dynamic friction between machine components. Due to switching or the like, an impact on the mechanical structure or an increase in synchronization error may occur.

  In the control device 10 according to the embodiment shown in FIGS. 10 to 12, after the spindle 12 is accelerated and reversely rotated by position control to a predetermined rotational position, the spindle 12 notified to the spindle controller 18 by the numerical controller 16. In accordance with the spindle command CS of only the total return rotation amount S0 ′ and the maximum return rotation speed V0 ′, the spindle 12 is accelerated at the maximum output to execute the return operation, and the maximum corresponding to the reverse rotation acceleration A0 when the operation is reversed. While decelerating the spindle 12 at the deceleration A0 ′, the return operation to the return completion position is continuously executed in the shortest time and stopped at the return completion position. Therefore, according to the control device 10, it is not necessary to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 with respect to the numerical controller 12, and the spindle 12 can be configured with a simpler configuration. Acceleration / deceleration control that maximizes the acceleration capability of the tapping process can be performed to shorten the tapping cycle time.

  The configuration of the control device 10 according to the embodiment shown in FIGS. 10 to 12 can be described as a machine tool control method for controlling the synchronous operation of the main shaft 12 and the feed shaft 14. In this control method, the control device 10 acquires the total rotation amount S0 and the maximum rotation speed V0 of the spindle 12 from the machining start position to the target screw depth from the tapping program P, and sets the maximum rotation speed V0 to the target. As a value, the spindle 12 is accelerated and rotated at the maximum capacity from the machining start position toward the target screw depth, and the maximum acceleration A0 is detected based on the rotational position feedback value FBS of the spindle 12 during the acceleration rotation at the maximum capacity, and the total rotation Based on the amount S0 and the rotational position feedback value FBS, the remaining rotational amount Sr of the main shaft 12 from the current position to the target screw depth is detected, and based on the rotational position feedback value FBS, the current speed Vc of the main shaft 12 is detected. After the acceleration rotation at the maximum capacity, the spindle 12 is decelerated and rotated at the maximum capacity based on the maximum acceleration A0, the remaining rotation amount Sr, and the current speed Vc, and the target screw depth Without stopping the spindle 12 at the target screw depth, the spindle 12 is moved at a reverse rotation acceleration A0 (negative value) that is the same as the maximum deceleration A0 (negative value) in the deceleration rotation at the maximum capacity. Acceleration reverse rotation is performed up to a predetermined rotation position.

  Further, in this control method, the control device 10 acquires the total return rotation amount S0 ′ and the maximum return rotation speed V0 ′ of the main shaft 12 from the target screw depth to the return completion position from the tapping program P, and the maximum Using the return rotational speed V0 ′ as a target value, the main shaft 12 is accelerated and reversely rotated at a maximum capacity from a predetermined rotational position toward the return completion position, and the total return rotational amount S0 ′ and the rotational position feedback value FBS of the main shaft 12 are obtained. On the basis of this, the remaining return rotation amount Sr ′ of the main shaft 12 from the current position to the return completion position is detected, and the current speed Vc ′ of the reverse rotation of the main shaft 12 is detected based on the rotation position feedback value FBS. After the acceleration reverse rotation, the spindle 12 is decelerated and reversely rotated with the maximum capacity based on the reverse rotation acceleration A0 (negative value), the remaining return rotation amount Sr ′, and the reverse rotation current speed Vc ′. It is intended to stop at the return completion position.

10, 40, 50 Control device 12 Spindle 14 Feed axis 16 Numerical control section 18 Spindle control section 20 Rotation detection section 22 Feed axis control section 26 Spindle command output section 28 Feed axis command output section 30 Initial motion control section 32 Maximum acceleration detection section 34 Remaining rotation amount detection unit 36 Current speed detection unit 38 Positioning operation control unit 42 Feed detection unit 44 Feed operation control unit 46 Remaining feed amount detection unit 48 Position recognition unit 52 Synchronization error calculation unit 56 Display control unit

One aspect of the present invention is a machine tool control device that controls synchronous operation of a spindle and a feed axis, a numerical control unit that creates a spindle command and a feed axis command based on a tap machining program, and a spindle according to the spindle command A spindle control unit that controls the rotation operation of the spindle, a rotation detection unit that detects the rotation position of the spindle, and a feed axis control unit that controls the feed operation of the feed axis based on the rotation position of the spindle according to the feed axis command. The numerical control unit obtains the total spindle rotation speed and maximum rotation speed from the machining start position to the target screw depth from the tapping program, and uses the total rotation speed and maximum rotation speed as the spindle command. A spindle command output unit to be sent to the control unit. The spindle control unit has an initial operation control unit for accelerating and rotating the spindle at the maximum capacity from the machining start position to the target screw depth with the maximum rotation speed as a target value. The maximum acceleration detection unit that detects the maximum acceleration based on the rotation position of the spindle during acceleration rotation at the shaft, and the remaining rotation of the spindle from the current position to the target screw depth based on the total rotation amount and the rotation position of the spindle A remaining rotation amount detection unit for detecting the amount, a current speed detection unit for detecting the current speed of the main spindle based on the rotation position of the main shaft, and a maximum acceleration, a remaining rotation amount, and a current speed after the acceleration rotation at the maximum capacity. And a positioning operation control unit that decelerates and rotates the main shaft at a maximum deceleration corresponding to the maximum acceleration to reach a target screw depth.

Another aspect of the present invention is a method for controlling a machine tool that controls synchronous operation of a main shaft and a feed shaft, wherein the control device includes a total amount of rotation of the main shaft from a machining start position to a target screw depth. The maximum rotation speed is acquired from the tap machining program, the maximum rotation speed is set as the target value, the spindle is accelerated from the machining start position to the target screw depth at the maximum capacity, and the spindle rotates during the acceleration rotation at the maximum capacity. The maximum acceleration is detected based on the position feedback value, the remaining amount of rotation of the main spindle from the current position to the target screw depth is detected based on the total rotation amount and the rotation position feedback value, and the main spindle is detected based on the rotation position feedback value. current detecting the speed, after acceleration rotation at maximum capacity, based on the maximum acceleration and the remaining amount of rotation and the current speed, depth target screw rotated at a speed at the maximum deceleration that corresponds to the maximum acceleration of the spindle To reach a control method.

When the control device 10 according to the above embodiment causes the spindle 12 to perform a cutting operation from the machining start position to the target screw depth, the numerical control unit 16 controls the spindle control unit 18 with the total rotation amount S0 of the spindle 12. Only the maximum rotation speed V0 is notified as the spindle command CS, and the spindle control unit 18 accelerates the spindle 12 with the maximum output using the maximum allowable current for the maximum rotation speed V0 in accordance with the spindle command CS. , And based on the maximum acceleration A0 and the remaining rotation amount Sr of the main shaft 12 and the current speed Vc that are sequentially detected, the cutting operation to the target screw depth is performed in the shortest time while the main shaft 12 is decelerated at the maximum deceleration A0. It is constituted so that the target screw depth can be reached by continuously executing. Therefore, according to the control device 10, there is no need to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 to the numerical control unit 16 , and the spindle can be configured with a simpler configuration. It is possible to reduce the tapping cycle time by performing acceleration / deceleration control that maximizes the acceleration capability of twelve.

Further, in the control device 10 according to the above embodiment, when the spindle 12 performs the return operation from the target screw depth to the return completion position, the numerical controller 16 makes the total return of the spindle 12 to the spindle controller 18. Only the rotation amount S0 ′ and the maximum return rotation speed V0 ′ are notified as the spindle command CS, and the spindle control unit 18 follows the spindle command CS and outputs the maximum output using the maximum allowable current with the maximum return rotation speed V0 ′ as a target. The main shaft 12 is accelerated to perform a return operation, and the main shaft 12 is moved to the maximum deceleration A0 'based on the maximum acceleration A0' during this time and the remaining rotational speed Sr 'of the main shaft 12 and the current speed Vc' which are sequentially detected. The return operation until the return completion position is continuously executed in the shortest time while decelerating at, and stopped at the return completion position. Therefore, according to the control device 10, there is no need to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 to the numerical control unit 16 , and the spindle can be configured with a simpler configuration. It is possible to reduce the tapping cycle time by performing acceleration / deceleration control that maximizes the acceleration capability of twelve.

In the example shown in FIG. 11, since the current speed of reverse rotation exceeds Vb (negative value) after reaching the predetermined rotational position (point C), the main shaft 12 is, for example, a servo in acceleration reverse rotation with the maximum capacity. Due to the characteristics of the motor, the reverse rotation acceleration of the main shaft 12 gradually decreases from A0 (time T8). At the time point D when the remaining return rotation amount Sr ′ becomes 1/2 of the total return rotation amount S0 ′ (that is, the rotation amount from the target screw depth becomes 1/2 of the total return rotation amount S0 ′), the spindle The operation 12 is changed from the reverse acceleration to the reverse deceleration, and at the time T9, the reverse rotation at the maximum capacity of the spindle 12 is executed. As described above, at time T8 to T9, the spindle control unit 18 controls the speed of the spindle 12 (a stepped speed command is exemplified by a broken line).

Next, the control device 10 executes Steps U3 and U4 in FIG. In step U5, as shown in FIG. 12, at the time T8, the acceleration reverse rotation with the maximum capacity of the main shaft 12 is executed, and the current speed Vc ′ (negative value) of the main shaft 12 becomes the maximum return rotation speed V0 ′ (negative). After that, over the time T11, the main shaft 12 reversely rotates at a constant speed V0 ′ and continues the return operation, and the remaining return rotation amount Sr ′ becomes equal to the acceleration rotation amount Sa ′. Thus, the operation of the spindle 12 changes from acceleration rotation to deceleration rotation, the deceleration reverse rotation with the maximum capacity of the spindle 12 is executed at time T9, and the position control to the return completion position of the spindle 12 is executed at time T10. . The operation of the main shaft 12 at times T8, T9, and T10 is the same as the operation of the main shaft 12 at times T8, T9, and T10 shown in FIG.

The control device 10 according to the embodiment shown in FIGS. 10 to 12 performs the cutting operation from the machining start position to the target screw depth on the main shaft 12 in the same manner as the control devices 10, 40 and 50 according to the embodiment of FIGS. When performing, the numerical control unit 16 notifies only the total rotation amount S0 and the maximum rotation speed V0 of the main shaft 12 to the main shaft control unit 18 as the main shaft command CS, and the main shaft control unit 18 follows the main shaft command CS. The spindle 12 is accelerated with the maximum output using the maximum allowable current with the maximum rotational speed V0 as a target, and the cutting operation is executed. At the same time, the maximum acceleration A0 and the remaining rotational amount Sr of the spindle 12 and the current speed detected sequentially. Based on Vc, the spindle 12 is decelerated at the maximum deceleration A0, and the cutting operation up to the target screw depth is continuously executed in the shortest time to reach the target screw depth. Therefore, according to the control device 10, there is no need to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 to the numerical control unit 16 , and the spindle can be configured with a simpler configuration. It is possible to reduce the tapping cycle time by performing acceleration / deceleration control that maximizes the acceleration capability of twelve.

In the control device 10 according to the embodiment shown in FIGS. 10 to 12, after the spindle 12 is accelerated and reversely rotated by position control to a predetermined rotational position, the spindle 12 notified to the spindle controller 18 by the numerical controller 16. In accordance with the spindle command CS of only the total return rotation amount S0 ′ and the maximum return rotation speed V0 ′, the spindle 12 is accelerated at the maximum output to execute the return operation, and the maximum corresponding to the reverse rotation acceleration A0 when the operation is reversed. While decelerating the spindle 12 at the deceleration A0 ′, the return operation to the return completion position is continuously executed in the shortest time and stopped at the return completion position. Therefore, according to the control device 10, there is no need to set or adjust parameters for creating an acceleration / deceleration command corresponding to the output characteristics of the spindle 12 to the numerical control unit 16 , and the spindle can be configured with a simpler configuration. It is possible to reduce the tapping cycle time by performing acceleration / deceleration control that maximizes the acceleration capability of twelve.

Claims (14)

A machine tool control device for controlling the synchronous operation of a main shaft and a feed shaft,
A numerical control unit that creates a spindle command and a feed axis command based on a tap machining program;
A spindle control unit for controlling the rotation operation of the spindle according to the spindle command;
A rotation detector for detecting a rotation position of the spindle;
In accordance with the feed axis command, comprising a feed axis control unit for controlling the feed operation of the feed axis based on the rotational position,
The numerical control unit obtains the total rotation amount and the maximum rotation speed of the spindle from the machining start position to the target screw depth from the tapping program, and calculates the total rotation amount and the maximum rotation speed. A spindle command output unit that sends the spindle command to the spindle control unit,
The spindle control unit
An initial operation control unit for accelerating and rotating the spindle at a maximum capacity from the machining start position toward the target screw depth with the maximum rotation speed as a target value;
A maximum acceleration detector that detects a maximum acceleration based on the rotational position during acceleration rotation at the maximum capacity;
Based on the total rotation amount and the rotation position, a remaining rotation amount detection unit that detects a remaining rotation amount of the spindle from the current position to the target screw depth;
A current speed detector for detecting a current speed of the spindle based on the rotational position;
A positioning operation control unit that, after accelerating rotation at the maximum capacity, based on the maximum acceleration, the remaining rotation amount, and the current speed, causes the spindle to rotate at a reduced speed to reach the target screw depth;
A control device comprising: A feed detector for detecting the feed position of the feed shaft;
The numerical control unit acquires a total feed amount and a screw pitch of the feed shaft from the machining start position to the target screw depth from the tapping program, and the total feed amount and the screw pitch. A feed axis command output unit that sends the feed axis command to the feed axis control unit,
The feed axis controller is
A feed operation control unit for controlling a feed operation of the feed shaft based on the screw pitch and the rotational position;
A remaining feed amount detection unit that detects a remaining feed amount of the feed shaft from the current position to the target screw depth based on the total feed amount and the feed position;
The control device according to claim 1.   The control device according to claim 2, wherein the numerical control unit includes a position recognition unit that recognizes a current position of the main shaft based on the remaining rotation amount and recognizes a current position of the feed shaft based on the remaining feed amount. .   The control device according to claim 2, wherein the numerical control unit includes a synchronization error calculation unit that calculates a synchronization error of the synchronous operation based on the remaining rotation amount, the remaining feed amount, and the screw pitch.   The control device according to claim 1, wherein the positioning operation control unit stops the main shaft at the target screw depth. The numerical control unit monitors the remaining rotation amount and determines that tapping has reached the target screw depth when the remaining rotation amount is equal to or less than a first predetermined value, and outputs the spindle command output. The total return rotation amount and maximum return rotation speed of the main shaft from the target screw depth to the return completion position are acquired from the tapping program, and the total return rotation amount and the maximum return rotation speed are acquired. To the spindle control unit as the spindle command,
The spindle control unit is configured such that the initial motion control unit accelerates and reversely rotates the spindle at a maximum capacity from the target screw depth toward the return completion position with the highest return rotation speed as a target value, and detects the maximum acceleration. A maximum acceleration of reverse rotation based on the rotation position during acceleration reverse rotation at the maximum capacity, and the remaining rotation amount detection unit detects a current position based on the total return rotation amount and the rotation position. The remaining return rotation amount of the main spindle from the return completion position to the return completion position, the current speed detection unit detects the current speed of reverse rotation of the main spindle based on the rotation position, and the positioning operation control unit After the acceleration reverse rotation at the maximum capacity, the spindle is decelerated and reverse rotated at the maximum capacity based on the maximum acceleration of the reverse rotation, the remaining return rotation amount, and the current speed of the reverse rotation, and the return completion position To stop,
The control device according to claim 5.   The positioning operation control unit accelerates the spindle to a predetermined rotational position with the same reverse rotation acceleration as the maximum deceleration in the deceleration rotation at the maximum capacity without stopping the spindle at the target screw depth. The control device according to claim 1, wherein the control device is reversely rotated. The numerical control unit monitors the remaining rotation amount and determines that tapping has reached the target screw depth when the remaining rotation amount is equal to or less than a first predetermined value, and outputs the spindle command output. The total return rotation amount and maximum return rotation speed of the main shaft from the target screw depth to the return completion position are acquired from the tapping program, and the total return rotation amount and the maximum return rotation speed are acquired. To the spindle control unit as the spindle command,
The spindle control unit is configured to cause the initial operation control unit to rotate the spindle at a maximum capacity from the predetermined rotation position toward the return completion position with the highest return rotation speed as a target value, and to perform the remaining rotation. An amount detection unit detects a residual return rotation amount of the spindle from the current position to the return completion position based on the total return rotation amount and the rotation position, and the current speed detection unit detects the rotation position. And detecting the current speed of the reverse rotation of the main spindle based on the acceleration, the positioning operation control unit after the acceleration reverse rotation at the maximum capacity, the acceleration of the reverse rotation, the amount of return rotation, and the current speed of the reverse rotation Based on the above, the spindle is decelerated and reversely rotated at maximum capacity and stopped at the return completion position.
The control device according to claim 7.   9. The numerical control unit according to claim 6, wherein the numerical control unit monitors the remaining return rotation amount and determines that the return operation is completed when the remaining return rotation amount is equal to or less than a second predetermined value. Control device. A feed detector for detecting the feed position of the feed shaft;
When it is determined that tapping has reached the target screw depth, the numerical control unit calculates a total return feed amount and a screw pitch of the feed shaft from the target screw depth to the return completion position. A feed axis command output unit that is acquired from the tapping program and sends the total return feed amount and the screw pitch to the feed axis control unit as the feed axis command,
The feed axis controller is
A feed operation control unit for controlling a return feed operation of the feed shaft based on the screw pitch and the rotational position;
A residual feed amount detector that detects a residual feed amount of the feed shaft from the current position to the return completion position based on the total return feed amount and the feed position;
The control device according to claim 6, 8 or 9.   11. The numerical control unit according to claim 10, further comprising a position recognition unit that recognizes a current position of the main shaft based on the residual return rotation amount and recognizes a current position of the feed shaft based on the residual return amount. Control device.   The control according to claim 10 or 11, wherein the numerical control unit includes a synchronization error calculation unit that calculates a synchronization error of the synchronous operation based on the residual rotation amount, the residual feed amount, and the screw pitch. apparatus.   The control device according to claim 4, wherein the numerical control unit includes a display control unit that displays the synchronization error on a display device. A machine tool control method for controlling synchronous operation of a spindle and a feed axis,
The control unit
The total amount of rotation and the maximum rotation speed of the main spindle from the machining start position to the target screw depth are acquired from the tap machining program,
The spindle is accelerated and rotated at maximum capacity from the machining start position toward the target screw depth with the maximum rotational speed as a target value,
Detecting the maximum acceleration based on the rotational position feedback value of the spindle during acceleration rotation at the maximum capacity;
Based on the total rotation amount and the rotation position feedback value, a remaining rotation amount of the main shaft from the current position to the target screw depth is detected,
Detecting the current speed of the spindle based on the rotational position feedback value;
After accelerating rotation at the maximum capacity, based on the maximum acceleration, the remaining rotation amount, and the current speed, the spindle is rotated at a reduced speed to reach the target screw depth.
Control method.

Images