Numerical control device and computer-readable storage medium

Abstract

This numerical control device comprises: a calculation unit that calculates, from a machining program, a start point and an end point of a reciprocating movement of a feed shaft; a control unit that synchronous controls, between the start point and the end point calculated by the calculation unit, a feed movement of the feed shaft and a relative rotational movement between a tool and a workpiece; and a determination unit that determines whether a condition for reversing the feed direction of the feed shaft has been satisfied before the feed shaft reaches the start point or the end point during synchronous control. When the determination unit determines that the condition for reversing the feed direction of the feed shaft has been satisfied, the control unit reveres the feed direction of the feed shaft before the feed shaft reaches the start point, or the end point.

Description

[Technical Field]

[0001] The present disclosure relates to a numerical control device and a computer-readable storage medium. [Background technology]

[0002] It is known that when honing the inner surface of a hole, grinding marks consisting of intersecting spiral grooves are imparted to the machined surface. These grinding marks function as lubrication grooves that retain lubricant when a sliding object slides inside the hole. For example, the grinding marks act as lubrication grooves when a piston slides inside a cylinder. Patent Document 1 discloses synchronous control of the feed rate and rotation speed of a tool to maintain a constant intersection angle of the grinding marks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-224753 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the feed rate and rotation rate of the tool are controlled synchronously, the rotation of the tool is temporarily stopped when the feed direction of the tool is reversed. If the rotation of the tool is started after the rotation of the tool has stopped, a large frictional force will be generated between the tool and the workpiece, which may result in a deterioration in the quality of the machined surface.

[0005] Therefore, it is desirable to improve the quality of the machined surface in the honing of the inner surface of a hole. [Means for solving the problem]

[0006] The numerical control device includes a calculation unit that calculates the start point and end point of the reciprocating motion of the feed axis from the machining program, and a The aforementioned the starting point, and The aforementionedBetween the ends, For each control period, Feed axis feed operation Number of pulse signals related to and the relative rotational movement between the tool and the workpiece. Number of pulse signals related to a control unit that controls the synchronization of the The aforementioned During synchronous control The aforementioned The feed axis The aforementioned Start point or The aforementioned Before reaching the end The aforementioned a determination unit that determines whether a condition for reversing the feed direction of the feed axis is satisfied, The aforementioned By the Judgment Department The aforementioned If the conditions are deemed to be met, The aforementioned The control unit The aforementioned The feed axis The aforementioned the starting point, or The aforementioned Before reaching the end The aforementioned Feed direction of the feed axis only Invert.

[0007] A computer-readable storage medium calculates a start point and an end point of a reciprocating motion of a feed axis from a machining program, and The aforementioned the starting point, and The aforementioned Between the ends, For each control period, Feed axis feed operation Number of pulse signals related to and the relative rotational movement between the tool and the workpiece. Number of pulse signals related to and synchronously controlling the The aforementioned During synchronous control The aforementioned The feed axis The aforementioned Start point or The aforementioned Before reaching the end The aforementioned determining whether a condition for reversing the feed direction of the feed axis is satisfied; The aforementioned If the conditions are deemed to be met, The aforementioned The feed axis The aforementioned the starting point, or The aforementioned Before reaching the end The aforementioned Feed direction of the feed axis only and storing instructions for causing a computer to execute the following: [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to improve the quality of the machined surface in honing the inner surface of a hole. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram showing an example of a hardware configuration of a machine tool. [Figure 2] FIG. 1 is a diagram showing an outline of honing processing. [Figure 3] FIG. 10 is a diagram illustrating crosshatching. [Figure 4] FIG. 2 is a diagram illustrating an example of a function of a numerical control device. [Figure 5] FIG. 10 is a diagram showing an example of a honing program. [Figure 6A] FIG. 4 is a diagram illustrating an example of a pulse signal output to a servo amplifier. [Figure 6B] FIG. 10 is a diagram illustrating an example of a pulse signal output to a spindle amplifier. [Figure 7A] FIG. 10 is a diagram showing an example of a pulse signal output to a servo amplifier in the prior art. [Figure 7B] FIG. 10 is a diagram showing an example of a pulse signal output to a spindle amplifier in the prior art. [Figure 8] FIG. 10 is a diagram illustrating an example of the operation of the tool. [Figure 9] FIG. 10 is a diagram showing a change in the position of a tool during honing. [Figure 10] 3 is a flowchart illustrating an example of processing executed in the numerical control device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Numerical control devices according to embodiments of the present disclosure will be described below with reference to the drawings. Note that not all combinations of features described in the following embodiments are necessarily required to solve the problems. In addition, more detailed explanation than necessary may be omitted. Furthermore, the following description of the embodiments and the drawings are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the scope of the claims.

[0011] A numerical control device is, for example, a control device that controls industrial machinery. Industrial machinery includes machine tools and industrial robots. Machine tools include, for example, lathes, machining centers, drilling centers, and multi-tasking machines. Note that, below, a numerical control device that controls a machine tool will be described as an example.

[0012] FIG. 1 is a block diagram showing an example of the hardware configuration of a machine tool equipped with a numerical control device.

[0013] The machine tool 1 includes a numerical control device 2, an input / output device 3, a servo amplifier 4, a servo motor 5, a spindle amplifier 6, a spindle motor 7, and auxiliary equipment 8.

[0014] The numerical control device 2 is a device that controls the entire machine tool 1. The numerical control device 2 includes a hardware processor 201, a bus 202, a ROM (Read Only Memory) 203, a RAM (Random Access Memory) 204, and a non-volatile memory 205.

[0015] The hardware processor 201 is a processor that controls the entire numerical control device 2 in accordance with a system program. The hardware processor 201 reads the system program stored in the ROM 203 via the bus 202 and performs various processes based on the system program. The hardware processor 201 controls the servo motor 5 and the spindle motor 7 based on the machining program. The hardware processor 201 is, for example, a CPU (Central Processing Unit) or an electronic circuit.

[0016] The hardware processor 201 analyzes the machining program and outputs control commands to the servo motor 5 and the spindle motor 7, for example, for each control period.

[0017] The bus 202 is a communication path that connects the various pieces of hardware within the numerical control device 2. The various pieces of hardware within the numerical control device 2 exchange data via the bus 202.

[0018] The ROM 203 is a storage device that stores a system program for controlling the entire numerical control device 2. The ROM 203 is a computer-readable storage medium.

[0019] The RAM 204 is a storage device that temporarily stores various data and functions as a work area for the hardware processor 201 to process various data.

[0020] The nonvolatile memory 205 is a storage device that retains data even when the machine tool 1 is turned off and no power is supplied to the numerical control device 2. The nonvolatile memory 205 stores, for example, machining programs and various parameters. The nonvolatile memory 205 is a computer-readable storage medium. The nonvolatile memory 205 is configured, for example, by a battery-backed memory or an SSD (Solid State Drive).

[0021] The numerical control device 2 further includes an interface 206 , an axis control circuit 207 , a spindle control circuit 208 , a PLC (Programmable Logic Controller) 209 , and an I / O unit 210 .

[0022] The interface 206 connects the bus 202 and the input / output device 3. The interface 206 sends various data processed by the hardware processor 201 to the input / output device 3, for example.

[0023] The input / output device 3 is a device that receives and displays various data via the interface 206. The input / output device 3 also accepts input of various data and sends the data via the interface 206 to, for example, the hardware processor 201.

[0024] The input / output device 3 is, for example, a touch panel. When the input / output device 3 is a touch panel, the input / output device 3 is, for example, a capacitive touch panel. Note that the touch panel is not limited to a capacitive touch panel and may be a touch panel of another type. The input / output device 3 is installed in an operation panel (not shown) in which the numerical control device 2 is housed.

[0025] The axis control circuit 207 is a circuit that controls the servo motor 5. The axis control circuit 207 receives a control command from the hardware processor 201 and outputs a command to drive the servo motor 5 to the servo amplifier 4. The axis control circuit 207 sends, for example, a torque command to control the torque of the servo motor 5 to the servo amplifier 4.

[0026] The servo amplifier 4 receives a command from the axis control circuit 207 and supplies a current to the servo motor 5 .

[0027] The servo motor 5 is driven by receiving a current supply from the servo amplifier 4. The servo motor 5 is connected to, for example, a ball screw that drives a tool post. When the servo motor 5 is driven, structures of the machine tool 1, such as the tool post, move in the directions of the feed axes. The servo motor 5 has a built-in encoder (not shown) that detects the position and feed speed of the feed axis. Position feedback information and speed feedback information indicating the position and feed speed of the feed axis, respectively, detected by the encoder are fed back to the axis control circuit 207. In this way, the axis control circuit 207 performs feedback control of the feed axis.

[0028] The spindle control circuit 208 is a circuit for controlling the spindle motor 7. The spindle control circuit 208 receives a control command from the hardware processor 201 and sends a command to the spindle amplifier 6 to drive the spindle motor 7. The spindle control circuit 208 sends, for example, a spindle speed command to the spindle amplifier 6 to control the rotation speed of the spindle motor 7.

[0029] The spindle amplifier 6 receives a command from the spindle control circuit 208 and supplies a current to the spindle motor 7 .

[0030] The spindle motor 7 is driven by receiving a current supplied from the spindle amplifier 6. The spindle motor 7 is connected to the main shaft and rotates the main shaft.

[0031] The PLC 209 is a device that executes a ladder program to control the auxiliary device 8. The PLC 209 sends commands to the auxiliary device 8 via an I / O unit 210.

[0032] The I / O unit 210 is an interface that connects the PLC 209 and the auxiliary device 8. The I / O unit 210 sends a command received from the PLC 209 to the auxiliary device 8.

[0033] The auxiliary device 8 is a device that is installed in the machine tool 1 and performs auxiliary operations in the machine tool 1. The auxiliary device 8 operates based on commands received from the I / O unit 210. The auxiliary device 8 may also be a device that is installed in the periphery of the machine tool 1. The auxiliary device 8 is, for example, a tool changer, a cutting fluid injection device, or an opening / closing door drive device.

[0034] Next, we will explain the machining performed by the machine tool 1. Honing is performed by the machine tool 1. Honing is a process in which the workpiece and the tool are reciprocated and rotated relative to each other while the tool is pressed against the inner surface of a hole. The hole to be machined is, for example, a cylinder. The tool used in honing is a grinding wheel.

[0035] Figure 2 is a diagram explaining the outline of honing. In honing, a grinding stone attached to a spindle moves back and forth inside a hole while rotating. The grinding stone has a diameter expansion function, and processes the inner surface of the hole while applying pressure to the inner surface.

[0036] The workpiece and the tool rotate and reciprocate relative to each other. For example, the tool may rotate and reciprocate while the workpiece is fixed. Alternatively, the workpiece may rotate and reciprocate while the tool is fixed. Alternatively, one of the tool or the workpiece may rotate, while the other reciprocates. Below, an example will be described in which machining is performed while the tool rotates and reciprocates.

[0037] Honing creates a mesh-like grinding mark on the inner surface of the hole. The mesh-like grinding mark is formed by multiple spiral, parallel grinding marks that intersect with each other at a predetermined angle. The grinding marks function as lubrication grooves that retain lubricating oil when a piston moves inside the hole, for example. Hereinafter, the grinding marks formed by honing are referred to as crosshatching.

[0038] Figure 3 is an explanatory diagram of the crosshatching formed on the inner surface of a hole. It is desirable for the crosshatching to be formed at a constant angle throughout the hole. Therefore, in the honing process, synchronous control is performed to synchronize the feed rate and rotational speed of the tool. When synchronous control is performed, the crosshatching is formed at a constant angle. As a result, multiple crosshatchings intersect with each other at a constant angle.

[0039] Next, the function of the numerical control device 2 will be described.

[0040] 4 is a diagram showing an example of the functions of the numerical control device 2. The numerical control device 2 includes a storage unit 21, a calculation unit 22, a control unit 23, and a determination unit 24. The storage unit 21 is realized, for example, by storing various data in a RAM 204 or a non-volatile memory 205. The calculation unit 22, the control unit 23, and the determination unit 24 are realized, for example, by the hardware processor 201 performing arithmetic processing using a system program stored in a ROM 203, and a machining program and various data stored in the non-volatile memory 205.

[0041] The storage unit 21 stores processing programs, which include, for example, a honing program.

[0042] FIG. 5 is a diagram showing an example of a honing program. In the honing program, a positioning command "G00X_Y_Z_;" is specified to position the tool at the positioning point. "_" indicates that a specific numerical value is entered. The numerical values ​​following "X", "Y", and "Z" respectively specify the X-coordinate, Y-coordinate, and Z-coordinate positions in a specific coordinate system.

[0043] "G_X_Y_Z_R_M_S_F_;" written on the line following the positioning command is a honing cycle command for executing honing.

[0044] "G_" is a G code that indicates a honing cycle. The G code is designated by, for example, "G" and a predetermined two-digit number.

[0045] "X_Y_" is a code that specifies the X and Y coordinate positions where the hole will be formed in a predetermined coordinate system. "M_" is an M code that specifies the type of honing process.

[0046] "S_" is an S code that specifies the rotational speed of the spindle. "R_" is a code that specifies the distance from the tool positioning point to the starting point of the tool's reciprocating motion. The starting point is also called the R point. The starting point is located, for example, at a position about 1 / 3 of the length of the grinding wheel from the entrance of the hole into the hole. When the tool is located at the starting point, about 1 / 3 of the tip of the grinding wheel is inserted into the hole.

[0047] "Z_" is a code that specifies the distance from the start point to the end point of the tool's reciprocating motion. The end point is also called the Z point. The end point is, for example, a position that is about 2 / 3 of the length of the grinding wheel outside the hole from the exit of the hole. When the tool is positioned at the end point, about 1 / 3 of the base end of the grinding wheel is inserted inside the hole. "Z_" may also be a code that specifies the position of the end point in a specified coordinate system. "F_" is an F code that specifies the cutting feed rate.

[0048] The honing program is not limited to the format shown in FIG. 5. For example, the crosshatch angle may be specified using "Q_". Here, the crosshatch angle is, for example, the angle at which multiple crosshatches intersect with each other. Also, the hole diameter may be specified using ",D_".

[0049] The calculation unit 22 calculates the start point and end point of the reciprocating motion of the feed axis from the machining program. The calculation unit 22 calculates the position of the start point based on, for example, the positioning point specified in the positioning command and "R_" specified in the honing cycle command. The calculation unit 22 also calculates the position of the end point based on the calculated position of the start point and "Z_" specified in the honing cycle command. The start point and end point are expressed, for example, by coordinate values ​​in the workpiece coordinate system.

[0050] The control unit 23 synchronizes the feed motion of the feed axis and the relative rotational motion between the tool and the workpiece between the start point and end point calculated by the calculation unit 22. In the synchronized control, the control unit 23 synchronizes the relative rotational motion between the tool and the workpiece, for example, based on the feed motion of the feed axis. In this case, the synchronized control can be said to be control that makes the rotational motion of the rotation axis follow the feed speed of the feed axis. Alternatively, the synchronized control can be said to be control that makes the position of the rotation axis follow the position of the feed axis.

[0051] The determination unit 24 determines whether a condition for reversing the feed direction of the feed axis is satisfied before the feed axis reaches the start point or the end point during synchronous control. The condition for reversing the feed direction is a condition for changing the feed direction to the opposite direction. When the feed direction is toward the end point, the determination unit 24 determines whether a condition for reversing the feed direction is satisfied before the tool reaches the end point. In this case, the reversal direction is toward the start point.

[0052] If the feed direction is toward the start point, the determination unit 24 determines whether or not the condition for reversing the feed direction is satisfied before the tool reaches the start point. In this case, the reversal direction is toward the end point.

[0053] The condition is, for example, that the rotational speed in the rotational operation reaches or falls below a predetermined rotational speed. Under synchronous control, the feed speed of the feed axis is decelerated near the start or end point, and the rotational speed of the rotary axis is also decelerated. The condition for reversing the feed direction of the feed axis is that this decelerated rotational speed falls below a predetermined rotational speed.

[0054] If the judgment unit 24 determines that the condition is satisfied, the control unit 23 reverses the feed direction of the feed axis before the feed axis reaches the start point or the end point. Specifically, the control unit 23 reverses the feed direction by outputting a command to reverse the feed direction of the feed axis to the servo amplifier 4. The command to reverse is a pulse signal.

[0055] Fig. 6A is a diagram showing an example of pulse signals output to a servo amplifier. The vertical axis represents the number of pulse signals in one control cycle, and the horizontal axis represents time. The positive side represents the number of pulse signals when moving the feed axis in the direction toward the end point, and the negative side represents the number of pulse signals when moving the feed axis in the direction toward the start point. Fig. 6B shows the number of pulse signals output to the spindle amplifier when the pulse signal shown in Fig. 6A is output.

[0056] When decelerating the feed speed of the feed axis, the control unit 23 gradually reduces the number of pulse signals output to the servo amplifier for each control cycle, as shown in Fig. 6A. Furthermore, when the condition for reversing the feed direction of the feed axis is satisfied, the control unit 23 outputs a pulse signal to the servo amplifier for moving the feed axis in a direction toward the start point from the next control cycle. The control unit 23 gradually increases the number of pulses.

[0057] When the control unit 23 decelerates the feed speed of the feed axis, it gradually reduces the number of pulse signals output to the spindle amplifier for each control cycle, as shown in Fig. 6B. Furthermore, when the condition for reversing the feed direction of the feed axis is satisfied, the control unit 23 outputs a pulse signal to the spindle amplifier for rotating the rotary axis from the next control cycle. Therefore, the rotation of the rotary axis does not stop.

[0058] For comparison, an example of a pulse signal output to a servo amplifier and an example of a pulse signal output to a spindle amplifier in the prior art are shown in FIGS. 7A and 7B, respectively.

[0059] When the control unit decelerates the feed speed of the feed axis, as shown in FIG. 7A, it gradually reduces the number of pulse signals output to the servo amplifier for each control cycle. When the feed axis reaches the end point, the control unit stops outputting the pulse signals. From the control cycle following the control cycle in which the output of the pulse signals was stopped, the control unit outputs pulse signals to the servo amplifier to move the feed axis in the direction toward the start point. Thereafter, the control unit gradually increases the number of pulses.

[0060] When the control unit decelerates the feed speed of the feed axis, as shown in Figure 7B, it gradually reduces the number of pulse signals output to the spindle amplifier for each control cycle. When the feed axis reaches the end point, the control unit stops outputting pulse signals. From the control cycle following the control cycle in which the output of pulse signals was stopped, the control unit outputs pulse signals to the spindle amplifier to rotate the rotating axis. Therefore, the rotating axis stops when it reaches the end point.

[0061] Next, the operation of the tool in the honing process will be described.

[0062] Figure 8 shows an example of the operation of a tool in honing. First, the tool is positioned at the positioning point (operation 1). At this time, the rotation of the spindle to which the tool is attached is stopped. Next, the tool moves to the starting point (operation 2).

[0063] Next, the tool starts to rotate and moves toward the end point (operation 3). While the tool is moving toward the end point, the feed rate and rotation rate of the tool are controlled by synchronous control. As the tool approaches the end point, the feed rate of the feed axis is decelerated and the rotation rate of the tool is also decelerated.

[0064] If the conditions for reversing the feed direction of the feed axis are met before the tool reaches the end point, the feed direction of the tool is reversed (operation 4). At this time, the rotation of the tool does not stop.

[0065] When the feed direction of the feed axis is reversed, the feed speed of the feed axis gradually increases, and the rotation speed of the tool also gradually increases (operation 5). While the tool is moving toward the starting point, the feed speed and rotation speed of the tool are controlled by synchronization control. Furthermore, as the tool approaches the starting point, the feed speed of the feed axis decreases, and the rotation speed of the tool also decreases.

[0066] If the conditions for reversing the feed direction of the feed axis are met before the tool reaches the start point, the feed direction of the tool is reversed (operation 6). At this time, the rotation of the tool does not stop.

[0067] After steps 3 to 6 have been repeated a predetermined number of times, the tool returns to the positioning point and the honing process is completed.

[0068] Figure 9 shows the change in the position of the tool in the Z-axis direction during honing. The tool moves from the start point toward the end point. As the feed axis approaches the end point and the conditions for reversing the feed axis are met, the feed axis reverses. Therefore, the feed direction of the feed axis reverses before reaching the end point. When the feed direction reverses, the feed axis moves toward the start point. Also, as the feed axis approaches the start point and the conditions for reversing the feed axis are met, the feed direction of the feed axis reverses. Therefore, the feed direction of the feed axis reverses before reaching the start point.

[0069] Next, the processing executed in the numerical control device 2 will be described.

[0070] 10 is a flowchart showing an example of processing executed by the numerical control device 2. First, the calculation unit 22 calculates the start point and end point of the reciprocating motion of the feed axis from the machining program (step S1).

[0071] Next, the control unit 23 synchronously controls the feed operation of the feed axis and the relative rotation operation between the tool and the workpiece between the start point and the end point calculated by the calculation unit 22 (step S2).

[0072] If the processing is completed (Yes in step S3), the process ends.

[0073] If the machining has not yet ended, the determination unit 24 determines whether or not the condition for reversing the feed direction of the feed axis is satisfied before the feed axis reaches the start point or the end point (step S4).

[0074] If the determining unit 24 determines that the condition is not satisfied (No in step S5), the synchronization control continues until the condition is satisfied.

[0075] If the judgment unit 24 determines that the condition is met (Yes in step S5), the control unit 23 reverses the feed direction of the feed axis before the feed axis reaches the start point or the end point (step S6) and continues to control the feed axis.

[0076] As described above, the numerical control device 2 includes the calculation unit 22 that calculates the start point and end point of the reciprocating motion of the feed axis from the machining program, the control unit 23 that synchronizes the feed motion of the feed axis and the relative rotational motion between the tool and the workpiece between the start point and the end point calculated by the calculation unit 22, and the determination unit 24 that determines whether a condition for reversing the feed direction of the feed axis is satisfied before the feed axis reaches the start point or the end point during the synchronized control. If the determination unit 24 determines that the condition is satisfied, the control unit 23 reverses the feed direction of the feed axis before the feed axis reaches the start point or the end point. The condition for reversing the feed direction of the feed axis can be that the rotational speed in the rotational motion reaches or exceeds a predetermined rotational speed.

[0077] Therefore, the numerical control device 2 can reverse the feed direction of the feed axis without stopping the rotation of the rotary axis, thereby preventing a decrease in the quality of the machined surface of the workpiece.

[0078] In the above-described embodiment, the control unit 23 reverses the feed direction of the feed axis when the rotation speed of the rotation axis reaches a predetermined rotation speed or less. However, the condition for reversing the feed direction of the feed axis is not limited to this. For example, the control unit 23 may reverse the feed direction of the feed axis when the feed speed of the feed axis reaches a predetermined feed speed or less.

[0079] The control unit 23 may reverse the feed direction of the feed axis on the condition that a position error between the position of the feed axis and the rotation angle of the rotation axis, which occurs when the feed direction of the feed axis is reversed, is estimated to be less than a predetermined reference position error.The control unit 23 may also reverse the feed direction of the feed axis on the condition that a speed error between the feed speed of the feed axis and the rotation speed of the rotation axis, which occurs when the feed direction of the feed axis is reversed, is estimated to be less than a predetermined reference speed error.

[0080] The relational equations showing the relationship between the position of the feed axis and the position error, and the relational equations showing the relationship between the feed rate and the speed error may be calculated in advance based on, for example, experiments, etc. Furthermore, the numerical control device 2 may include an estimation unit that estimates the position error or the speed error in real time based on the relational equations.

[0081] In addition, the control unit may reverse the feed direction of the feed axis on the condition that it is estimated that the angular error of the crosshatch angle that occurs when reversing the feed direction of the feed axis will be less than a predetermined reference angle error.

[0082] The angle error is calculated based on, for example, the relational expression showing the relationship between the feed speed of the feed axis and the speed error, and the following formula 1 or formula 2 for calculating the crosshatch angle. Formula 1 is a formula for calculating the crosshatch angle in the feed-per-minute mode. Formula 2 is a formula for calculating the crosshatch angle in the feed-per-minute mode.

[0083]

number

[0084]

number

[0085] In the above-described embodiment, the condition for reversing the feed direction of the feed axis may be specified in the machining program. For example, the condition may be specified using "P_" in the honing cycle command. "P_" may specify, for example, at least one of the rotation speed of the rotary axis, the feed speed of the feed axis, the reference position error, the reference speed error, and the reference angle error.

[0086] The present disclosure is not limited to the above-described embodiments, and can be appropriately modified without departing from the spirit and scope of the present disclosure. In the present disclosure, any component of the embodiments can be modified or omitted. [Explanation of symbols]

[0087] 1 Machine tools 2. Numerical control device 21 Memory section 22 Calculation section 23 Control Unit 24 Judgment Department 201 Hardware Processor 202 Bus 203 ROM 204 RAM 205 Non-volatile memory 206 Interface 207 Axis control circuit 208 Spindle control circuit 209 PLC 210 I / O units 3 Input / Output Devices 4 Servo amplifiers 5 Servo motors 6 Spindle amplifier 7 Spindle motor 8 Auxiliary equipment

Claims

1. a calculation unit that calculates a start point and an end point of a reciprocating motion of the feed axis from a machining program; a control unit that synchronizes and controls the number of pulse signals related to the feed operation of the feed axis and the number of pulse signals related to the relative rotation operation between the tool and the workpiece for each control period between the start point and the end point calculated by the calculation unit; a determination unit that determines whether or not a condition for reversing the feed direction of the feed axis is satisfied during the synchronization control and before the feed axis reaches the start point or the end point, When the determining unit determines that the condition is satisfied, the control unit reverses only the feed direction of the feed axis before the feed axis reaches the start point or the end point. Numerical control device.

2. 2. The numerical control device according to claim 1, wherein the condition is that the rotation speed in the rotation operation reaches a predetermined rotation speed or less, or that the feed speed in the feed operation reaches a predetermined feed speed or less.

3. 2. The numerical control device according to claim 1, wherein the condition is that a position error between the position of the feed axis and the rotation angle of the rotary axis, which occurs when the feed direction of the feed axis is reversed, is estimated to be less than a predetermined reference position error, or that a speed error between the feed speed of the feed axis and the rotation speed of the rotary axis, which occurs when the feed direction of the feed axis is reversed, is estimated to be less than a predetermined reference speed error.

4. 2. The numerical control device according to claim 1, wherein the condition is that an angular error of a crosshatch angle occurring when reversing the feed direction of the feed axis is estimated to be less than a predetermined reference angular error.

5. Calculating the start point and end point of the reciprocating motion of the feed axis from the machining program; Synchronously controlling the number of pulse signals related to the feed operation of the feed axis and the number of pulse signals related to the relative rotation operation between the tool and the workpiece for each control period between the calculated start point and end point; determining whether or not a condition for reversing the feed direction of the feed axis is satisfied during the synchronous control and before the feed axis reaches the start point or the end point; When it is determined that the condition is satisfied, only the feed direction of the feed axis is reversed before the feed axis reaches the start point or the end point; A computer-readable storage medium that stores instructions for causing a computer to execute the above.

Images