Control method and machine tool having a rotary feed axis

Abstract

The present invention provides a machine tool and a control method thereof that improves machining efficiency while reducing the influence of inertial forces caused by the acceleration and deceleration of a linear feed axis, which acts as a disturbance load on the drive device of the rotary feed axis. [Solution] In a control method for a machine tool 10, the NC device 42 reads a command for a machining program, and if the command includes a clamp command for the first rotary feed axis A, the clamp device 40a clamps the first rotary feed axis A, and the linear acceleration / deceleration control unit 52 sends a first value to the NC device 42 as an acceleration / deceleration parameter for the first linear feed axis, and if the command includes an unclam command for the first rotary feed axis A, the clamp device 40a unclams the first rotary feed axis A, and the linear acceleration / deceleration control unit 52 sends a second value smaller than the first value to the NC device 42 as an acceleration / deceleration parameter, and the NC device 42 sends a movement command using the acceleration / deceleration parameter.

Description

[Technical Field]

[0001] The present invention relates to a control method for a machine tool having a rotary feed axis and to a machine tool. [Background technology]

[0002] Some machining centers are designed to further improve machining efficiency by adding two rotational axes, such as a trunnion table as shown in Patent Document 1, in addition to the three linear axes of the machine tool. In such machine tools, torque interference can occur between the motors of the linear and rotary feed axes due to the difference in the center of gravity of the trunnion table and the center of the rotary feed axis, which can affect machining efficiency.

[0003] On the other hand, rotary tables equipped with a clamping device on the rotary feed axis are known. For example, Patent Document 1 discloses a method for correcting errors in the position and orientation of the tool relative to the workpiece in a machine tool equipped with a clamping device for clamping or unclamping the rotary feed axis, by calculating a correction value for the rotary axis when the rotary feed axis is unclamped, and maintaining the correction value for the rotary axis at the previous value when the rotary feed axis is clamped.

[0004] However, in machining operations where the rotary feed axis is unclamped and the linear and rotary feed axes are controlled simultaneously, the posture and center of gravity of the cradle rotatably mounted on the trunnion table change moment by moment. As a result, the inertial force generated by the acceleration and deceleration of the linear motion may place a load on the drive mechanism of the rotary feed axis, but the invention described in Patent Document 1 does not take into consideration the effects of the acceleration and deceleration of the linear motion. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5713764 [Overview of the project] [Problems that the invention aims to solve]

[0006] In view of the above circumstances, the present invention aims to provide a machine tool and a control method thereof that improve machining efficiency while reducing the influence of inertial force due to the acceleration and deceleration of the linear feed axis acting as an external disturbance load on the drive device of the rotary feed axis, in a machine tool having a rotary feed axis that rotates together with the linear feed axis and around a central axis perpendicular to the linear feed axis. [Means for solving the problem]

[0007] One aspect of the present invention relates to a control method for a machine tool having a rotary feed axis, comprising: a machine tool body having a rotary feed axis that moves a rotary table or slewing spindle head in a linear fashion, and a rotary feed axis that rotates the rotary table or slewing spindle head around a central axis perpendicular to the rotary feed axis; a clamping device for clamping or unclamping the rotary feed axis; and a linear acceleration / deceleration control unit for controlling the acceleration and deceleration of the rotary feed axis, wherein the NC device reads a command from an input machining program; if the command includes a command to clamp the rotary feed axis, the clamping device clamps the rotary feed axis and the linear acceleration / deceleration control unit sends a pre-stored first value to the NC device as an acceleration / deceleration parameter for the linear feed axis; if the command includes an unclamping command for the rotary feed axis, the clamping device unclams the rotary feed axis and the linear acceleration / deceleration control unit sends a second value smaller than the first value to the NC device as an acceleration / deceleration parameter; and the NC device sends a movement command using the acceleration / deceleration parameter to the drive device of the linear feed axis.

[0008] One aspect of the present invention relates to a machine tool having a linear feed axis that moves a rotary table or a slewing spindle head in a linear fashion, and a rotary feed axis that rotates the rotary table or slewing spindle head around a central axis perpendicular to the linear feed axis, comprising: a clamping device for clamping or unclamping the rotary feed axis; an NC device that reads commands from a machining program and sets acceleration and deceleration for the read linear feed axis movement commands, and sends movement commands for the linear feed axis and rotary feed axis to the drive devices of each feed axis; a clamping control unit that sends a clamping command or an unclamping command to the clamping device based on the command read by the NC device and receives a completion signal after the clamping device completes clamping or unclamping; a parameter storage unit that stores acceleration and deceleration parameters for the linear feed axis; and an acceleration and deceleration parameter selection unit that, when a completion signal is received after the clamping device completes clamping or unclamping, selects the corresponding acceleration and deceleration parameter from the parameter storage unit, or, if the command includes setting acceleration and deceleration parameters, selects the acceleration and deceleration parameter included in the command and sends it to the NC device. [Effects of the Invention]

[0009] According to one aspect of the present invention, a control method for a machine tool having a rotary feed axis, if the command read by the NC device includes a clamp command for the rotary feed axis, the clamping device of the machine tool clamps the rotary feed axis, and the linear acceleration / deceleration control unit can send a pre-stored first value to the NC device as the acceleration / deceleration parameter for the linear feed axis. If the command read by the NC device includes an unclam command for the rotary feed axis, the clamping device of the machine tool unclams the rotary feed axis, and the linear acceleration / deceleration control unit can send a second value smaller than the first value to the NC device as the acceleration / deceleration parameter. The NC device can then send a movement command using the acceleration / deceleration parameter set in this way to the drive unit of the linear feed axis. Therefore, the machine tool can generate and send a movement command to the drive unit in response to the clamping and unclamping of the rotary feed axis, in order to reduce the influence of the inertial force due to the acceleration / deceleration of the linear feed axis acting as a disturbance load on the drive unit of the rotary feed axis. This suppresses interference between the linear feed axis and the rotary feed axis and improves machining efficiency.

[0010] According to one aspect of the present invention, a machine tool having a rotary feed axis includes a clamping device for clamping or unclamping the rotary feed axis, a clamping control unit that sends a clamping command or an unclamping command to the clamping device based on a command read by an NC device and receives a completion signal after the clamping or unclamping of the clamping device is completed, and a linear acceleration / deceleration control unit for controlling the acceleration and deceleration of the linear feed axis. Therefore, when a completion signal is received after the clamping or unclamping of the clamping device is completed, the machine tool can select the corresponding acceleration / deceleration parameter from a parameter storage unit that stores the acceleration / deceleration parameters of the linear feed axis, or, if the command read by the NC device includes the setting of acceleration / deceleration parameters, it can select the acceleration / deceleration parameter included in the command and send it to the NC device. Therefore, in response to the clamping and unclamping of the rotary feed axis, the machine tool can generate a movement command to reduce the influence of the inertial force due to the acceleration / deceleration of the linear feed axis acting as a disturbance load on the drive unit of the rotary feed axis and send it to the drive unit. This suppresses interference between the linear feed axis and the rotary feed axis and improves machining efficiency. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows an external perspective view of a machine tool according to the first embodiment. [Figure 2] Figure 2 shows a block diagram of the machine tool according to this embodiment. [Figure 3] Figure 3 shows the time series of the feed axis speed of the linear feed axis according to this embodiment. [Figure 4] Figure 4 shows a flowchart of the control method for a machine tool according to this embodiment. [Figure 5A] Figure 5A shows a side view of the cradle (with the workpiece mounting surface facing horizontally upwards). [Figure 5B] Figure 5B shows a side view of the cradle (with the workpiece mounting surface oriented vertically). [Figure 5C] Figure 5C shows a side view of the cradle (with the workpiece mounting surface facing diagonally downwards). [Figure 5D]FIG. 5D shows a side view of the cradle (the workpiece mounting surface is obliquely upward). [Figure 5E] FIG. 5E shows a side view of the cradle (the workpiece mounting surface is obliquely downward). [Figure 6] FIG. 6 shows an external perspective view of the machine tool according to the second embodiment. [Figure 7A] FIG. 7A shows a plan view of the rotary table (the rotation angle is 180 degrees). [Figure 7B] FIG. 7B shows a plan view of the rotary table (the rotation angle is 135 degrees). [Figure 7C] FIG. 7C shows a plan view of the rotary table (the rotation angle is 90 degrees). [Figure 7D] FIG. 7D shows a plan view of the rotary table (the rotation angle is 45 degrees). [Figure 7E] FIG. 7E shows a plan view of the rotary table (the rotation angle is 0 degrees). [Figure 7F] FIG. 7F shows a plan view of the rotary table (the rotation angle is -45 degrees). [Figure 7G] FIG. 7G shows a plan view of the rotary table (the rotation angle is -90 degrees). [Figure 8] FIG. 8 shows a side view of the swivel type spindle head according to the first modification. [Figure 9] FIG. 9 shows a front view of the trunnion table according to the second modification. [Figure 10] FIG. 10 shows a plan view of the machining center according to the third modification.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, a machine tool having a rotary feed shaft according to an embodiment and its control method will be described with reference to the accompanying drawings. The same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted. For ease of understanding, the scale of the drawings may be changed for the description.

[0013] (First Embodiment) Figure 1 shows an external perspective view of a machine tool 10 according to the first embodiment. The machine tool 10 includes a machining center 12 as the main body of the machine tool for machining. In addition, a machining chamber 24 is formed in front of the machining center 12, which has space for machining a workpiece with a tool (not shown) attached to (gripped) by the spindle unit 22.

[0014] The machine tool 10 is equipped with a bed 14 placed on the floor of a factory or other facility where it is installed. A column 16 is erected on the upper surface of the rear portion 14b of the bed 14, which is on the Z-axis rear side. A spindle unit 22 is located on the front side of the column 16, and the spindle unit 22 is configured to move linearly along a second linear feed axis in the left-right direction (X-axis direction) and a third linear feed axis in the up-down direction (Y-axis direction). For this reason, an X-axis feed device for moving the spindle unit 22 along the X-axis direction and a Y-axis feed device for moving it along the Y-axis direction (both not shown) are provided on the rear portion 14b of the bed and the column 16, respectively. In addition, at the boundary between the front portion 14a of the bed 14 and the rear portion 14b of the bed 14, retractable left and right telescopic covers 18 and an upper and lower telescopic cover 20 are provided to cover the front side of the column 16 in order to prevent chips generated during machining from scattering towards the rear portion 26b of the bed. In this example, the column 16 moves linearly along the rear of the bed 14b in the X-axis direction. However, the column may be fixed to the rear of the bed, a saddle is provided on the column that moves linearly along the X-axis direction, and a spindle device is provided on the saddle that moves linearly along the Y-axis direction.

[0015] Rails 38 extending in the front-to-back direction (Z-axis direction) are arranged on both the left-to-right direction (X-axis direction) of the upper surface of the front part 14a of the bed, and a trunnion table 26 is arranged above the rails 38. Trunnion base legs 32 are formed on both the left and right sides of the lower end of the trunnion table 26, and the trunnion base legs 32 are arranged on the rails 38 via a carriage 36. The carriage 36 is configured to move the trunnion table 26 linearly along a first linear feed axis in the front-to-back direction (Z-axis direction). For this reason, a Z-axis feed device (not shown) is arranged on the bed 14 to move the trunnion table 26 along the Z-axis direction. This makes it possible to machine a workpiece by relatively moving a workpiece attached to the trunnion table 26 side moving along the first linear feed axis and a tool held by the spindle device moving along the second and third linear feed axes.

[0016] The trunnion table 26 consists of a trunnion base 30 on which trunnion base legs 32 are formed, and a central axis O located inside the trunnion base 30 in the left-right direction (X-axis direction). A The system includes a cradle 28 configured to swing along a first rotary feed axis A, which rotates around the system. A workpiece mounting base 34 is positioned in the center of the cradle 28, having a workpiece mounting surface 34a on its upper side for mounting a workpiece. The workpiece mounting base 34 is configured to rotate relative to the cradle 28 and has a central axis O perpendicular to the workpiece mounting surface 34a on which the workpiece is mounted. B In Figure 1, the central axis O in the vertical direction (Y-axis direction) is the surrounding area. B It can be rotated along a second rotary feed axis B, which acts as a rotary feed axis that rotates around it.

[0017] Furthermore, the trunnion table 26 is equipped with a clamping device 40a for clamping or unclamping the rotation of the first rotary feed axis A of the cradle 28 and a clamping device 40b for clamping or unclamping the rotation of the second rotary feed axis B of the workpiece mounting surface 34a (see Figure 2 for both). The clamping devices 40a and 40b are, for example, equipped with a structure that clamps a disk that rotates simultaneously with the tilting oscillating feed axis and the rotary feed axis using hydraulic pads. The clamping devices 40a and 40b are also configured to detect clamping or unclamping by proximity sensors based on the position of the clamping pads and to transmit a clamping completion signal / unclamping completion signal. Here, the workpiece mounting table 34 is described as being configured to oscillate along the first rotary feed axis A and to rotate along the second rotary feed axis B, but it is not limited to this configuration, and the workpiece mounting table may be configured to oscillate only along the first rotary feed axis.

[0018] Figure 2 shows a block diagram of the machine tool 10. The machine tool 10 includes an NC device 42 for controlling the machining center 12. Here, the NC device 42 includes a read / interpretation unit 44, an acceleration / deceleration setting unit 46, a servo control unit 48, and a feed motor drive control unit 50. The read / interpretation unit 44 is configured to read and interpret the machining program input by the operator and send commands including movement commands to the mechanisms in the NC device 42 from the read / interpretation unit 44 onward. The acceleration / deceleration setting unit 46 sends movement commands that take into account acceleration / deceleration parameters in addition to the movement commands read from the machining program. The servo control unit 48 interpolates the movement commands and distributes them from the first linear feed axis to the third linear feed axis, the first rotary feed axis A, and the second rotary feed axis B. It is also configured to correct the position commands and speed commands sent to each feed axis in response to the position and speed feedback signals returned from each feed axis of the machining center 12.

[0019] Furthermore, the feed motor drive control unit 50 is configured to amplify the output from the servo control unit 48 and generate a current to drive the drive devices (not shown) for each feed axis of the machining center 12. Here, a servo motor is used as the drive device. The torque of the servo motor of the first rotary feed axis A that oscillates the cradle 28 is set to a torque that can withstand the allowable cutting force that acts a vertically downward moment on the first rotary feed axis A when the straight-line distance between the center of gravity of the cradle 28 with the maximum load of workpiece (not shown) attached and the center of the rotation axis is horizontal in a side view, and that also incorporates a safety factor to allow the torque to oscillate in the direction of lifting the workpiece at a predetermined acceleration.

[0020] The machine tool 10 includes a machine control device 58 electrically connected to a machining center 12 and an NC device 42. The machine control device 58 is configured to send operation signals to each part of the machining center 12 in accordance with the M-code commands in the machining program read by the NC device 42, such as operation commands for turning the spindle motor ON / OFF, discharging / stopping coolant, changing tools, changing pallets, etc., and to control the operation of each part according to a predetermined sequence. For this reason, the machine control device 58 has a clamp control unit 60, and the clamp control unit 60 is configured to send a clamp command or unclam command for the first rotary feed axis A and the second rotary feed axis B to the clamp devices 40a and 40b if the command read by the reading interpretation unit 44 includes a clamp command or unclam command for the first rotary feed axis A and the second rotary feed axis B, and to receive a clamp or unclam completion signal when the clamping or unclamping of the clamp devices 40a and 40b is completed.

[0021] The machine tool 10 includes a linear acceleration / deceleration control unit 52 for controlling the acceleration and deceleration of the linear feed axis from the first linear feed axis to the third linear feed axis. The linear acceleration / deceleration control unit 52 includes a parameter storage unit 56 for storing acceleration / deceleration parameters of the linear feed axis, and an acceleration / deceleration parameter selection unit 54 for selecting acceleration / deceleration parameters stored in the parameter storage unit 56. The acceleration / deceleration parameter selection unit 54 is configured to select the corresponding acceleration / deceleration parameter from the parameter storage unit 56 when it receives a clamp completion signal or an unclamping completion signal via the machine control device 58 after the clamping or unclamping of the clamping devices 40a, 40b is completed. Here, when the acceleration / deceleration parameter selection unit 54 receives a clamp completion signal, it selects a first value stored in the parameter storage unit 56. Also, when the acceleration / deceleration parameter selection unit 54 receives an unclamping completion signal, it selects a second value that is smaller than the first value stored in the parameter storage unit 56. The first and second values ​​are values ​​set based on the relationship between the configuration of the first linear feed axis to the third linear feed axis and the configuration of the first rotary feed axis A and the second rotary feed axis B. Furthermore, the acceleration / deceleration parameter selection unit 54 is configured to select the acceleration / deceleration parameter included in the command as the third value, instead of the first and second values, when the command read by the reading and interpretation unit 44 includes the setting of an acceleration / deceleration parameter, and the value of this acceleration / deceleration parameter is between the first and second values. The acceleration / deceleration parameter selection unit 54 is configured to send the selected acceleration / deceleration parameter to the acceleration / deceleration setting unit 46 of the NC device 42. Here, the linear acceleration / deceleration control unit 52 is described as being configured independently of the machining center 12 and the NC device 42, but it is not limited to this configuration and may be incorporated into the machining center, NC device, or machine control device.

[0022] The acceleration / deceleration parameters described herein refer to the acceleration value around 50% of the command speed (when the speed exceeds or falls below 50% of the command speed). Figure 3 shows an example of a time series of linear axis feed speed with time t on the horizontal axis. As shown in Figure 3, the acceleration value, which is the derivative (dv / dt) of the linear axis feed speed v around 50% of the command speed, refers to the acceleration / deceleration parameters. Here, the magnitude of the acceleration / deceleration parameters means that the absolute value of the acceleration value (|dv / dt|) is large. Therefore, a large acceleration / deceleration parameter means that the acceleration time constant, which represents the time it takes to reach 63.2% of the command speed from the start of movement, is small, and the deceleration time constant, which represents the time it takes to stop from 63.2% of the command speed, is small. Furthermore, a large acceleration / deceleration parameter means that the rise time and fall time are small.

[0023] Figures 5A to 5E show the relationship between the rotational orientation of the tilting oscillating feed axis (first rotary feed axis A) of the cradle 28 and the acceleration / deceleration of the first linear feed axis. The spindle device 22 is located on the right side of each figure, but is omitted from the illustration here. The cradle 28 shown in Figures 5A to 5E each has a different rotational orientation. Figure 5A shows the workpiece mounting surface 34a in a horizontal upward position, and Figure 5E shows the workpiece mounting surface 34a in a nearly horizontal downward position. The center of gravity G of the cradle 28 is usually on the central axis O of the first rotary feed axis A. A It is located in a different position, and when the cradle 28 is accelerated or decelerated along the direction of travel LD (Z-axis direction), the first rotary feed shaft A has acceleration, center of gravity position G and the central axis O of the first rotary feed shaft A. A An inertial force (moment of inertia) acts depending on the vertical distance from the center of gravity G and the central axis O of the first rotational feed axis A. In the rotational postures shown in Figures 5A and 5E, the center of gravity G and the central axis O of the first rotational feed axis A are in the same position. A As the vertical distances L1 and L5 increase, the inertial force increases. On the other hand, when the workpiece mounting surface 34a is aligned vertically as shown in Figure 5B, or when the workpiece mounting surface 34a is angled downwards as shown in Figure 5C, the distance between the center of gravity G and the central axis O of the first rotational feed axis A increases compared to the cases in Figures 5A and 5E. ASince the vertical distances L2 and L3 from it become smaller (L5 > L1 > L3 > L2), the influence of the inertial force becomes relatively smaller. Also, in the state where the work mounting surface 34a is obliquely upward as shown in FIG. 5D, the center axis O of the center of gravity position G and the first rotational feed axis A A are almost at the same vertical position (L2 > L4 ≒ 0), so the influence of the inertial force hardly occurs.

[0024] In the machine tool 10 having the trunnion table 26, when accelerating and decelerating with a relatively large acceleration in the Z-axis direction, depending on the rotational posture of the cradle 28, the acceleration and the center axis O of the center of gravity position G and the first rotational feed axis A AAn inertial force (moment of inertia) corresponding to the vertical distance acts on the first rotary feed axis A, which may result in exceeding the rated torque of the drive device (e.g., servo motor) for the first rotary feed axis A. This can lead to risks such as the servo motor becoming overloaded, reducing the rotation angle of the first rotary feed axis A and the positioning accuracy of the machined surface, or the drive device overheating and triggering a thermal alarm. For this reason, conventionally, the acceleration and deceleration of the Z axis was always set to a relatively small, safe value. In machine tools 10 that perform machining by mounting a workpiece (not shown) on the workpiece mounting base 34 of a trunnion table 26 having the first rotary feed axis A, when performing so-called indexing machining such as drilling, surface milling, and pocket machining, the first rotary feed axis A is often clamped by a clamping device 40a and the machining is performed with the first rotary feed axis A positioned at a certain angle. In this invention, we focused on this point and conceived the idea of ​​changing the acceleration / deceleration parameter of the Z axis depending on whether the first rotary feed axis A is mechanically clamped (at which time, power supply to the motor of the first rotary feed axis A is also turned OFF) or unclamped. That is, when the first rotary feed axis A is unclamped, the acceleration / deceleration parameter of the Z axis is set to a relatively small, safe value (second value) as in the conventional method, and when it is clamped, it is set to a first value that is larger than the second value. Therefore, the acceleration / deceleration parameter selection unit 54 selects the first value (acceleration value) set in this way after receiving the clamping completion signal. As a result, even if the acceleration / deceleration parameter of the Z axis is set relatively large to move the trunnion table 26 quickly in order to perform rapid traverse positioning and high-speed feed cutting of the X, Y, and Z axes, the inertial force acting on the first rotary feed axis A can be supported by the clamping device 40a. This makes it possible to improve machining efficiency without putting a burden on the servo motor of the first rotary feed axis A.

[0025] On the other hand, in machining operations that perform multi-axis simultaneous feeding using the first rotary feed axis A and three linear feed axes (X axis, Y axis, and Z axis), the first rotary feed axis A cannot be clamped. Therefore, in machining operations that perform multi-axis simultaneous feeding, if a rotational posture such as those shown in Figures 5A and 5E may occur, the acceleration / deceleration parameter selection unit 54 is configured to select a second value (acceleration value) that is smaller than the first value stored in the parameter storage unit 56 after receiving the unclamping completion signal. This suppresses or prevents the servo motor of the first rotary feed axis A from becoming overloaded due to the inertial force acting on the first rotary feed axis A due to acceleration / deceleration in the Z axis direction, thereby maintaining machining accuracy.

[0026] Furthermore, although the acceleration / deceleration parameter selection unit 54 is affected by inertial force, if the effect is relatively small as shown in Figures 5B, 5C, and 5D, and if the command (M code) read by the reading and interpretation unit 44 after receiving the unclamping completion signal includes a third value (acceleration value) of the acceleration / deceleration parameter, and this value lies between the first and second values, the acceleration / deceleration parameter selection unit 54 can select the third value as the value of the acceleration / deceleration parameter.

[0027] The effects and advantages of the machine tool 10 having a rotary feed axis and its control method according to this embodiment will be explained below through the flowchart shown in Figure 4.

[0028] As shown in Figure 4, when the machine tool 10 starts machining in step S10, it moves to step S20, where the reading and interpretation unit 44 of the NC device 42 reads commands from the machining program entered by the operator. If the read commands include a clamp command, it moves to step S30, where the reading and interpretation unit 44 sends a clamp command to the clamp control unit 60. Furthermore, upon receiving the clamp command, the clamp control unit 60 moves to step S40, activates the clamping devices 40a and 40b to clamp the first rotary feed axis A and the second rotary feed axis B, and then moves to step S50.

[0029] When the process moves to step S50, the acceleration / deceleration parameter selection unit 54 receives the clamping completion signal and selects the first value (acceleration value) stored in the parameter storage unit 56 as the acceleration / deceleration parameter. Once the acceleration / deceleration parameter selection unit 54 has selected the first value, the process moves to step S60, where the NC device 42 sends a command including the acceleration / deceleration parameter to the machining center 12, and the machining center 12 begins machining. When the machining is completed, the process moves to step S70. If the machining program has not finished at that point, the process moves to step S20, and steps S30 to S60 are repeated for the remaining machining program. If the machining program has finished, the process moves to step S120 to complete the machining.

[0030] On the other hand, if the command read in step S20 includes an unclamping command, the process moves to step S30, where the reading interpretation unit 44 sends an unclamping command to the clamp control unit 60. Upon receiving the unclamping command, the clamp control unit 60 moves to step S80, activates the clamping devices 40a and 40b to unclam the first rotary feed axis A and the second rotary feed axis B, and then moves to step S90. After receiving the unclamping completion signal, the acceleration / deceleration parameter selection unit 54, if the command (M code) read by the reading interpretation unit 44 includes a third value (acceleration value) of the acceleration / deceleration parameter and is between the first and second values, moves to step S100. In step S100, the acceleration / deceleration parameter selection unit 54 selects the third value as the acceleration / deceleration parameter and moves to step S60 to start machining. The third value is selected, for example, in the unclamped state when the cradle 28 is in the rotational position shown in Figures 5B and 5C. Furthermore, if the command (M code) does not include a third value for the acceleration / deceleration parameter, or if the third value is not between the first and second values, the acceleration / deceleration parameter selection unit 54 proceeds to step S110. In step S110, the acceleration / deceleration parameter selection unit 54 selects the second value as the acceleration / deceleration parameter and proceeds to step S60 to start machining. The second value is selected, for example, in the unclamped state, when the cradle 28 is in the rotational position shown in Figures 5A, 5D, and 5E.

[0031] According to the machine tool 10 and its control method having a first rotary feed axis A according to this embodiment, the machine tool 10 includes clamping devices 40a and 40b for clamping or unclamping the first rotary feed axis A and the second rotary feed axis B, a clamping control unit 60 that sends clamping commands or unclamping commands to the clamping devices 40a and 40b based on commands read by the NC device 42 and receives a completion signal after the clamping or unclamping of the clamping devices 40a and 40b is completed, and a linear acceleration / deceleration control unit 52 for controlling the acceleration and deceleration of the first linear feed axis. Therefore, when a completion signal is received after the clamping or unclamping of the clamping devices 40a and 40b is completed, the corresponding acceleration / deceleration parameter can be selected from the parameter storage unit 56 that stores the acceleration / deceleration parameters of the first linear feed axis, or, if the command read by the NC device 42 includes the setting of acceleration / deceleration parameters, the acceleration / deceleration parameter included in the command can be selected and sent to the NC device 42. Therefore, the machine tool 10 can generate and send movement commands to the drive devices for the first rotary feed axis A and the second rotary feed axis B in response to the clamping and unclamping of the first rotary feed axis A and the second rotary feed axis B, in order to reduce the influence of the inertial force caused by the acceleration and deceleration of the first linear feed axis, which acts as a disturbance load on the drive devices for the first rotary feed axis A and the second rotary feed axis B. This suppresses the influence of the inertial force caused by the acceleration and deceleration of the first linear feed axis on the first rotary feed axis A and the second rotary feed axis B, and improves machining efficiency by allowing the Z axis to move quickly.

[0032] Furthermore, according to the machine tool 10 having a first rotary feed axis A and its control method according to this embodiment, the first value stored in the parameter storage unit 56 is the acceleration, the center of gravity position G, and the central axis O of the first rotary feed axis A. AEven when an inertial force (moment of inertia) corresponding to the vertical distance acts on the clamped first rotary feed axis A, the acceleration value is set such that it does not exceed the rated torque of the drive device for the first rotary feed axis A. Therefore, even if the acceleration / deceleration parameter of the Z axis is set relatively large to move the trunnion table 26 quickly in order to perform rapid traverse positioning and high-speed feed cutting on the X, Y, and Z axes, the inertial force acting on the first rotary feed axis A can be supported by the clamping device 40a. This reduces the load on the first rotary feed axis A and improves machining efficiency.

[0033] Furthermore, according to the machine tool 10 having the first rotary feed axis A and its control method according to this embodiment, even when the first rotary feed axis A is unclamped, the system is configured to select a second value (acceleration value) that is smaller than the first value stored in the parameter storage unit 56. This allows the acceleration, the center of gravity position G, and the central axis O of the first rotary feed axis A to be controlled. A Even when an inertial force (moment of inertia) acts on the first rotary feed axis A in proportion to its vertical distance, it is possible to suppress or prevent overloading of the servo motor and the occurrence of a thermal alarm, thereby maintaining machining accuracy.

[0034] Furthermore, according to the machine tool 10 having a first rotary feed axis A and its control method according to this embodiment, when the influence of inertial force on the first rotary feed axis A is relatively small, the acceleration / deceleration parameter selection unit 54, after receiving the unclamping completion signal, can select the third value (acceleration value) of the acceleration / deceleration parameter as the value of the acceleration / deceleration parameter if the command (M code) read by the reading and interpretation unit 44 includes a third value of the acceleration / deceleration parameter and this value is between the first value and the second value. This makes it possible to improve machining efficiency while suppressing the load on the first rotary feed axis A.

[0035] As described above, the machine tool 10 having the first rotary feed axis A and its control method according to this embodiment can improve machining efficiency while reducing the influence of inertial force due to the acceleration and deceleration of the first linear feed axis acting as a disturbance load on the drive device of the first rotary feed axis A.

[0036] In this embodiment, the machine tool 10 is described as a horizontal spindle machine, but the present invention is not limited to this and may also be applied to machine tools with vertical spindles.

[0037] In this embodiment, the cradle 28 of the machine tool 10 was described as having arms attached to both sides in the left-right direction. However, the present invention is not limited to this, and may also be applied to machine tools having a cantilever trunnion table in which the cradle is held by only one arm.

[0038] (Second Embodiment) The machine tool 70 and its control method according to the second embodiment will be described below with reference to Figures 6 and 7A to 7G. Elements similar to or corresponding to those in the first embodiment are denoted by the same reference numerals, and redundant explanations are omitted.

[0039] Figure 6 shows an external perspective view of the machine tool 70 according to the second embodiment. The machine tool 70 is similar to the machine tool 10 according to the first embodiment in that it has a horizontal spindle, but it differs from the machine tool 10 according to the first embodiment in that it has a rotary table with an angle plate instead of a trunnion table 26.

[0040] The machine tool 70 is equipped with a bed 14 placed on the floor of a factory or other facility where it is installed. A column base 72 is positioned on the upper surface of the rear portion 14b of the bed 14 on the Z-axis rear side, and a column 16 is positioned vertically above the column base 72. A spindle unit 22 is positioned on the front side of the column 16, and the column 16 is configured to move linearly relative to the column base 72 along a second linear feed axis in the left-right direction (X-axis direction). The spindle unit 22 is also configured to move linearly relative to the column 16 along a third linear feed axis in the up-down direction (Y-axis direction). For this reason, the column 16 is equipped with an X-axis servo motor 74 as a drive device for moving the spindle unit 22 along the X-axis direction and a Y-axis servo motor 76 as a drive device for moving it along the Y-axis direction.

[0041] A saddle 80, whose upper part is formed in the shape of a disc, is positioned on the upper surface of the front part 14a of the bed. The saddle 80 is configured to move back and forth along the Z-axis direction on the upper surface of the front part 14a of the bed by a Z-axis servo motor 78, which is a drive device positioned on the front part 14a of the bed side. The central axis O in the vertical direction (Y-axis direction) is located on the upper surface side of the saddle 80. B A B-axis table 82 is positioned to rotate the horizontal plane ±180 degrees along a second rotary feed axis B, which acts as a rotary feed axis that rotates around it. An angle base 86, which is formed in an L-shape when viewed from the side, is attached to the upper side of the B-axis table 82, and the central axis O in the front-to-back direction (Z-axis direction) is located on the upper part of the angle base 86. CA C-axis table 88 is rotatably supported to rotate infinitely on a vertical plane along a third rotary feed axis C that rotates around it. A workpiece mounting base 90 is detachably attached to the C-axis table 88. The upper surface of the workpiece mounting base 90, along the vertical direction, is the workpiece mounting surface 90a, and is configured to allow a workpiece (not shown) to be mounted. Here, the rotary-on-rotary table having the B-axis table 82, angle base 86, and C-axis table 88 described above is referred to as an angle plate type rotary table 84. Here, the angle plate type rotary table 84 is described assuming that the B-axis table 82 and C-axis table 88 are rotatable, but it is not limited to this configuration, and only the B-axis table may be configured to be rotatable.

[0042] Figures 7A to 7G show plan views of the angle plate type rotary table 84 to illustrate the relationship between the rotational orientation of the second rotary feed axis B and the acceleration / deceleration of the first linear feed axis. The B-axis table 82 of the angle plate type rotary table 84 shown in Figures 7A to 7G has different rotational orientations of the second rotary feed axis B. Here, the rotation angle of the B-axis table 82 is defined as 0 degrees (Figure 7E) when the workpiece mounting base 90 and workpiece face the spindle unit 22 along the Z-axis direction, and the rotation angle of the B-axis table 82 is defined as 180 degrees (Figure 7A) when the angle base 86 faces the spindle unit 22 along the Z-axis direction. The figures show the state rotated counterclockwise in 45-degree increments from 180 degrees to -90 degrees. The center of gravity G of the angle plate type rotary table 84 is the central axis O of the second rotary feed axis B. B Because they are in different positions, when the angle plate type rotary table 84 is accelerated or decelerated along the Z-axis direction, the second rotary feed axis B is in a position that is different from the center axis O of the second rotary feed axis B. B It may be affected by the inertial force (moment of inertia) that arises depending on the distance in the X-axis direction from the center of gravity G and the central axis O of the second rotational feed axis B. B The distance in the X-axis direction from the center of gravity G differs depending on the rotational orientation of the B-axis table 82. For example, when the rotation angles of the B-axis table 82 are 0 degrees and 180 degrees, as shown in Figures 7E and 7A, the distance between the center of gravity G and the central axis O of the second rotational feed axis B is different. BSince it is located on a straight line along the Z-axis direction, the distance in the X-axis direction becomes 0, and the second rotary feed axis B is hardly affected by inertial force. On the other hand, when the rotation angle of the B-axis table 82 is ±90 degrees as shown in FIGS. 7C and 7G, the center of gravity position G and the central axis O of the second rotary feed axis B B Since it is located on a straight line along the X-axis direction, the distance L in the X-axis direction becomes the maximum. For this reason, the second rotary feed axis B is likely to be greatly affected by inertial force. Further, when the rotation angle of the B-axis table 82 is 135 degrees and ±45 degrees as shown in FIGS. 7B, 7D, and 7F, the distance M (M < L) in the X-axis direction is obtained, and although it is smaller than the case where the rotation angle is ±90 degrees, the second rotary feed axis B can be affected by inertial force.

[0043] According to the machine tool 70 having the second rotary feed axis B according to the present embodiment and its control method, the first value stored in the parameter storage unit 56 is the first rotary feed axis B clamped, the acceleration, the center of gravity position G, and the central axis O of the second rotary feed axis B B Even when an inertial force (moment of inertia) corresponding to the vertical distance to acts, an acceleration value is set that does not exceed the rated torque of the drive device of the second rotary feed axis B. For this reason, in order to perform rapid feed positioning and high-speed feed cutting of the X-axis, Y-axis, and Z-axis, even if the acceleration / deceleration parameter of the Z-axis is made relatively large and the angle plate type rotary table 84 is moved sensitively, the inertial force acting on the second rotary feed axis B can be supported by the clamping device 40b. Thereby, the burden on the second rotary feed axis B can be suppressed, and the machining efficiency can be improved.

[0044] Furthermore, according to the machine tool 70 having the second rotary feed axis B according to the present embodiment and its control method, even when the second rotary feed axis B is unclamped, a second value (acceleration value) smaller than the first value stored in the parameter storage unit 56 is selected. As a result, the acceleration, the center of gravity position G, and the central axis O of the second rotary feed axis B BEven when an inertial force (moment of inertia) acts on the second rotary feed axis B in proportion to its distance in the X-axis direction, it is possible to suppress or prevent overloading of the drive mechanism of the second rotary feed axis B and the occurrence of a thermal alarm, thereby maintaining machining accuracy.

[0045] Furthermore, according to the machine tool 70 having a second rotary feed axis B and its control method according to this embodiment, when the influence of the inertial force on the second rotary feed axis B is relatively small, the acceleration / deceleration parameter selection unit 54, after receiving the unclamping completion signal, can select the third value (acceleration value) of the acceleration / deceleration parameter as the value of the acceleration / deceleration parameter if the command (M code) read by the reading and interpretation unit 44 includes a third value of the acceleration / deceleration parameter and this value is between the first value and the second value. This makes it possible to improve machining efficiency while suppressing the load on the second rotary feed axis B.

[0046] As described above, the machine tool 70 having a second rotary feed axis B and its control method according to this embodiment can improve machining efficiency while reducing the influence of inertial force due to the acceleration and deceleration of the first linear feed axis acting as a disturbance load on the drive device of the second rotary feed axis B.

[0047] (First variation) The following describes a machine tool and its control method according to the first modified example, using Figure 8. Elements that are the same as or corresponding to those in the first and second embodiments are denoted by the same reference numerals, and redundant explanations are omitted.

[0048] Figure 8 shows a side view of the swivel spindle head 100. The swivel spindle head 100 is mounted on an X-slider 102 that is configured to slide along the X-axis. The swivel spindle head 100 is configured so that the third rotary feed axis C is rotatable around the central axis Oc, and comprises a spindle head 106 and a fork 104 that swivels in the direction of the third rotary feed axis C and supports the spindle head 106 so that it can swivel in the direction of the first rotary feed axis A. If a heavy tool (not shown) is attached to the tip of the spindle head 106 configured in this way, there is a certain distance between the center of gravity of the spindle head 106 with the tool attached and the central axis Oc of the third rotary feed axis C. Therefore, when accelerating or decelerating along the linear feed axis in the X-axis or Z-axis direction, the third rotary feed axis C may be affected by the inertial force generated by the spindle head 106 with the tool attached. According to the modified machine tools 10, 70 and their control method having a third rotary feed axis C, the machining efficiency can be improved while suppressing the influence of inertial force on the third rotary feed axis C by setting the acceleration / deceleration parameter (acceleration / deceleration value) in the X-axis direction or the Z-axis direction to a first value when the clamped state is in place, and to a second or third value when the unclamped state is in place.

[0049] (Second variation) The following describes a machine tool and its control method according to a second modified example, using Figure 9 as a reference. Elements that are the same as or corresponding to those in the first and second embodiments are denoted by the same reference numerals, and redundant explanations are omitted.

[0050] Figure 9 shows a front view of a trunnion table 120 configured to slide along the X-axis. Here, the trunnion base 122 is configured to slide along the X-axis. The trunnion base 122 also includes a cradle 124 configured to swing on a first rotary feed axis A, and a workpiece mounting table 126 rotatably mounted on the cradle 124 on a second rotary feed axis B. Here, the central axis O of the second rotary feed axis B is located on the workpiece mounting table 126. BWhen a workpiece is positioned off-center (eccentric load EL), the acceleration and deceleration of the trunnion base 122 along the X-axis direction affects the drive mechanism of the second rotary feed axis B with inertial force. According to the machine tools 10, 70 and their control method having the second rotary feed axis B according to this modified example, by setting the acceleration / deceleration parameter (acceleration / deceleration value) in the X-axis direction to a first value when clamped, and to a second or third value when unclamped, the influence of inertial force on the second rotary feed axis B can be suppressed while improving machining efficiency.

[0051] (Third variation) Hereinafter, a machine tool 140 and its control method according to a third modified example will be described with reference to Figure 10. Elements that are the same as or corresponding to those in the first and second embodiments are denoted by the same reference numerals, and redundant explanations are omitted.

[0052] Figure 10 shows a plan view of a machine tool 140 comprising a column 142 configured to slide along the X-axis, a spindle unit 144 attached to the column 142, and a rotary table 146 configured to rotate by a second rotary feed axis B. Here, the central axis O of the second rotary feed axis B is on the rotary table 146. B When a workpiece (not shown) is positioned off-center, the acceleration and deceleration of the rotary table 146 along the Z-axis direction affects the drive mechanism of the second rotary feed axis B with inertial force. According to the machine tool 140 having the second rotary feed axis B and its control method according to this modified example, by setting the acceleration / deceleration parameter (acceleration / deceleration value) in the Z-axis direction to a first value when clamped, and to a second or third value when unclamped, the influence of inertial force on the second rotary feed axis B can be suppressed while improving machining efficiency.

[0053] The embodiments of machine tools 10, 70, and 140 having a first rotary feed axis A and a second rotary feed axis B have been described above, but the present invention is not limited to the above embodiments. In addition to the above, it is expected that those skilled in the art will understand that various modifications of the above embodiments are possible. [Explanation of symbols]

[0054] 10 Machine tools 12. Machining Center (Machine Tool Body) 26 Trunnion Table 28 Cradle 40a Clamping device 40b Clamping device 42 NC device 44 Reading and Interpretation Section 46 Acceleration / Deceleration Setting Section 52 Linear acceleration / deceleration control unit 54 Acceleration / Deceleration Parameter Selection Section 56 Parameter Storage Unit 60 Clamp control unit 70 Machine tools 84 Angle Plate Type Rotating Table 86 Angle Base 90a Workpiece mounting surface 100 Swivel type spindle head

Claims

1. A control method for a machine tool having a rotary feed axis, comprising: a machine tool body having a linear feed axis that moves a rotary table or a slewing spindle head in a straight line; a rotary feed axis that rotates the rotary table or the slewing spindle head around a central axis perpendicular to the linear feed axis; a clamping device for clamping or unclamping the rotary feed axis; and a linear acceleration / deceleration control unit for controlling the acceleration and deceleration of the linear feed axis, wherein The NC device reads commands from the input machining program, If the command includes a clamping command for the rotary feed shaft, the clamping device clamps the rotary feed shaft, and the linear acceleration / deceleration control unit sends a pre-stored first value as the acceleration / deceleration parameter for the linear feed shaft to the NC device. If the command includes an unclamping command for the rotary feed shaft, the clamping device unclams the rotary feed shaft, and the linear acceleration / deceleration control unit sends a second value smaller than the first value as the acceleration / deceleration parameter to the NC device. The NC device sends a movement command using the acceleration / deceleration parameters to the drive device of the linear feed axis. A control method for a machine tool having a rotary feed axis, including the above.

2. A control method for a machine tool having a rotary feed shaft according to claim 1, wherein when the clamping device unclams the rotary feed shaft, the command further includes setting the acceleration / deceleration parameter to a third value between the first value and the second value, the linear acceleration / deceleration control unit sends the third value to the NC device.

3. In a machine tool having a linear feed axis that moves a rotary table or a swivel spindle head in a straight line, and a rotary feed axis that rotates the rotary table or the swivel spindle head around a central axis perpendicular to the linear feed axis, A clamping device for clamping or unclamping the aforementioned rotary feed shaft, An NC device having a reading and interpretation unit for reading commands from a machining program, and an acceleration / deceleration setting unit for setting acceleration / deceleration to the movement commands of the linear feed axis that have been read, and sending the movement commands of the linear feed axis and the rotary feed axis to the drive devices of each feed axis, A clamp control unit sends a clamp command or an unclam command to the clamping device based on the command read by the NC device, and receives a completion signal after the clamping or unclamping is completed by the clamping device. A linear acceleration / deceleration control unit having: a parameter storage unit for storing acceleration / deceleration parameters of the linear feed axis; and an acceleration / deceleration parameter selection unit that, upon receiving the completion signal after the clamping or unclamping of the clamping device, selects the corresponding acceleration / deceleration parameter from the parameter storage unit, or, if the command includes setting the acceleration / deceleration parameter, selects the acceleration / deceleration parameter included in the command and sends it to the NC device; It is equipped with, If the command includes a clamping command for the rotary feed shaft, the clamping device clamps the rotary feed shaft, and the linear acceleration / deceleration control unit sends a pre-stored first value as the acceleration / deceleration parameter for the linear feed shaft to the NC device. If the command includes an unclamping command for the rotary feed shaft, the clamping device unclams the rotary feed shaft, and the linear acceleration / deceleration control unit sends a second value smaller than the first value as the acceleration / deceleration parameter to the NC device. A machine tool having a rotary feed shaft, characterized in that when the clamping device unclams the rotary feed shaft, the command further includes setting the acceleration / deceleration parameter to a third value between the first value and the second value, the linear acceleration / deceleration control unit sends the third value to the NC device.

4. The rotary feed axis is as described in claim 3, wherein the rotary table includes a workpiece mounting base, is positioned in the cradle of the trunnion table, and the rotary feed axis is an inclined oscillating feed axis that rotates the cradle around a horizontal central axis perpendicular to the linear feed axis along the horizontal direction.

5. The rotary table is an angle plate type rotary table on which an angle base having a vertical workpiece mounting surface is mounted and which rotates in a horizontal plane along the rotary feed axis about a vertical central axis, according to claim 3, a machine tool having a rotary feed axis.

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