JP2010099799A - Machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To gently stop the rotation of a tool magazine when the deviation amount between an actual rotating position of the tool magazine rotated by a servomotor and an indexing designated position of the tool magazine becomes excessive in a machine tool equipped with a tool changer. <P>SOLUTION: The deviation amount of a magazine shaft position is calculated from the difference between an actual rotating position in a magazine motor 55 and a rotating position indicated in the amount of movement command. When the amount of the magazine shaft position is larger than a threshold value concerning an over deviation amount error (S3; Yes), it is determined that an alarm is activated due to the over deviation amount error (S4), and a magazine shaft operation stop processing performing a stop operation with the rotational speed of the magazine motor 55 decelerated at a constant speed is started. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a machine tool including a tool changer.

  2. Description of the Related Art Conventionally, a machine tool is provided with a tool changer having a tool magazine for storing a plurality of tools, and can automatically change a tool attached to a spindle. This tool changer includes a servo motor and a speed reducer, and has a practical configuration in which a tool magazine is rotated via the speed reducer by driving the servo motor.

  For example, in the control method and control device for a tool magazine of Patent Document 1, a plurality of sprockets that are appropriately arranged in the same plane, an endless annular chain that hangs around the sprocket, and a plurality of tools that are connected to the chain at predetermined intervals. A tool magazine including a holding pot and a servomotor for driving a sprocket is disclosed.

  In this tool magazine, the sprocket is driven to rotate by a servo motor, and the chain is rotated accordingly. As a result, the tool holding pot connected to the chain moves in the same direction as the chain, and the predetermined tool holding pot is exchanged. I'm trying to figure out.

In a tool changer configured to rotate the tool magazine by driving the servo motor, if the servo motor is suddenly stopped while the tool magazine is rotating, the tool falls due to the inertial force acting on the tool stored in the tool magazine. There is a fear. Therefore, when the emergency stop button is pressed or a power failure occurs, the numerical control device is set to perform a stop operation while decelerating the servo motor based on the internal parameters set in the numerical control device.
JP 2002-200355 A

However, the servo motor indicated by the actual rotation position of the servo motor and the command value from the numerical control unit may cause the torque of the servo motor to be insufficient due to an increase in the viscosity of the lubricating grease in the reducer at low temperatures. In some cases, the amount of deviation from the rotation position becomes excessive.
Therefore, the deviation amount between the actual rotation position of the tool magazine and the index designation position of the tool magazine becomes excessive.

  In this case, since the magazine drive circuit urgently performs a stop operation, the stop operation is not performed while the servo motor is decelerated. Therefore, when the servo motor suddenly stops, the rotation of the tool magazine stops suddenly, and the tool stored in the tool magazine may fall. Thus, it is necessary to perform control so that the rotation of the tool magazine is not suddenly stopped even when the deviation amount is excessive.

  The object of the present invention is that in a machine tool provided with a tool changer, when the deviation amount between the actual rotation position of the tool magazine rotated by the servo motor and the index designation position of the tool magazine is excessive, This is to gently stop the rotation of the tool magazine.

  The machine tool according to claim 1 includes a tool magazine for storing a plurality of tools, a servo motor having a holding brake and rotating the tool magazine in response to a command from a numerical control device, In a machine tool including a tool changer to be replaced, the tool changer includes a rotation position detection unit that detects a rotation position of the servo motor, and the numerical control unit is detected by the rotation position detection unit. When the deviation amount between the rotation position of the servo motor and the rotation position of the servo motor indicated by the command value commanded to the servo motor from the numerical controller exceeds a predetermined threshold value, the servo motor is decelerated and controlled. The holding brake is operated for a predetermined time while the servo motor is operated in a non-excited state after the predetermined time has elapsed.

  In this machine tool, the servo motor rotation position detected by the rotation position detection means and the numerical control device when the torque of the servo motor is insufficient due to an increase in the viscosity of the lubricating grease in the speed reducer at low temperatures. When the deviation amount from the rotation position of the servo motor indicated by the command value commanded to the servo motor exceeds a predetermined threshold, the numerical control device operates the holding brake for a predetermined time while controlling the servo motor to decelerate. After a predetermined time has elapsed, the numerical control device operates the servo motor in a non-excited state. As a result, the rotation of the servo motor can be gently stopped, so that the tool magazine does not stop suddenly.

  The machine tool of claim 2 is characterized in that, in the invention of claim 1, the predetermined threshold is set based on a deviation counter overflow value that is an overflow value of the deviation amount and a deviation amount allowable ratio. Yes.

  According to a third aspect of the present invention, the numerical control device according to the first or second aspect of the invention is characterized in that the holding brake is actuated when the rotation speed of the servo motor is almost stopped.

  According to the first aspect of the present invention, the numerical control device includes the rotation position of the servo motor detected by the rotation position detecting means and the rotation position of the servo motor indicated by the command value commanded to the servo motor from the numerical control device. When the deviation amount exceeds the predetermined threshold value, the holding brake is operated for a predetermined time while the servomotor is controlled to decelerate, and after the predetermined time has elapsed, the servomotor is operated in a non-excited state. In such a case, the rotation of the tool magazine can be gently stopped by gently stopping the servo motor. Therefore, since a large inertia force does not act on the tool stored in the tool magazine, it is possible to prevent the tool from dropping.

  According to the second aspect of the present invention, the predetermined threshold is set based on the deviation counter overflow value, which is the deviation amount overflow value, and the deviation amount allowable ratio, so that a value lower than the deviation counter overflow value is used as the threshold value. Can be set. Thereby, since abnormality of a servomotor and a reduction gear can be discovered at an early stage, the safety at the time of tool exchange can be improved significantly.

  According to the invention of claim 3, since the numerical control device operates the holding brake when the rotation speed of the servo motor is almost stopped, it reliably prevents the tool stored in the tool magazine from dropping. be able to.

  Hereinafter, the best mode for carrying out the present invention will be described.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of a spindle head 3 and a tool changer 2 of a machine tool 1 according to an embodiment of the present invention. As shown in FIGS. 1 and 2, the machine tool 1 relatively moves the workpiece and the tool independently in the directions of the respective axes in the XYZ orthogonal coordinate system based on a command from the control device 30 (see FIG. 3). Thus, desired machining (for example, “boring”, “milling”, “drilling”, “cutting”, etc.) can be performed on the workpiece.

  The spindle head 3 is supported by a guide rail extending in the vertical direction on the front side of a column (not shown) extending vertically upward via a linear guide (not shown). A Z-axis motor 53 is fixed to the upper end of the spindle head 3 with a plurality of bolts 7. The Z-axis motor 53 drives the spindle head 3 up and down in the Z-axis direction (vertical direction in FIG. 1). A main shaft 3A that is rotatably supported is provided inside the main shaft head 3. A tool changer (ATC) 2 is provided on the front side of the spindle head 3 to attach and exchange a tool holder (not shown) of a tool (not shown) at the tip of the spindle 3A.

Next, the tool changer 2 will be described.
As shown in FIGS. 1 and 2, the tool changer 2 includes a tool magazine 10 that supports a plurality of tools, a magazine motor 55, a speed reducer 15, and the like. The tool magazine 10 is mainly composed of a cylindrical magazine base 11 with a flange and a plurality of grip arms 20 supported radially on the outer periphery of the magazine base 11. A magazine support (not shown) fixed to the front ends of the pair of frames 6 supports the magazine base 11 so as to be rotatable with respect to the magazine shaft 14.

As shown in FIGS. 1 and 2, the magazine base 11 mainly includes a cylindrical boss portion 13 into which the magazine shaft 14 is inserted, and a flange portion 12 provided in a hook shape on the front end side of the boss portion 13. It is.
A reduction gear 15 is disposed on the outer peripheral side of the magazine shaft 14, and a magazine motor 55 with a holding brake 55 b (see FIG. 3) is disposed on the upper side of the reduction gear 15. The magazine motor 55 rotates the tool magazine 10 via the speed reducer 15. On the outer peripheral side of the magazine base 11, 14 covers 21 are arranged in the circumferential direction at a required central angle, and the 14 grip arms 20 can be covered.

  In a magazine shaft operation stop process described later, when the rotation speed of the magazine motor 55 is almost stopped (50 rpm or less), the holding brake 55b is operated. Further, the magazine motor 55 has a dynamic brake function, the dynamic brake is activated when the magazine motor 55 is not energized (de-energized state), and the dynamic brake is released when the magazine motor 55 is energized (excited state). It is constituted as follows. The holding brake 55b is deactivated when the CPU 31 outputs an on signal to the magazine drive circuit 45, and is activated when an off signal is output. The magazine motor 55 is in an excited state during normal use by outputting an off signal to the magazine drive circuit 45 as a motor excitation signal when the machine tool power is turned on. In an emergency, the CPU 31 outputs an ON signal to the magazine drive circuit 45 to enter a non-excitation state.

Next, the electrical configuration of the control system of the machine tool 1 will be described.
As shown in FIG. 3, the control device 30 is configured to include a microcomputer, and includes an input interface 34, a CPU 31, a ROM 32, a RAM 33, and an input / output interface 35. The input interface 34 is connected to a keyboard 36 and a Z-axis origin sensor 37 that detects an origin (Z-axis origin) in the Z-axis of the main shaft 3A. The input / output interface 35 is connected to an X-axis motor 51, a Y-axis motor 52, a Z-axis motor 53, a main shaft motor 54, and a magazine motor 55 via drive circuits 41 to 45, respectively.

  The X-axis motor 51 and the Y-axis motor 52 are for moving a table (not shown) in the X-axis direction and the Y-axis direction, respectively. The Z-axis motor 53 drives the spindle head 3 to move up and down in the Z-axis direction. The magazine motor 55 is for rotating the tool magazine 10. The main shaft motor 54 is for rotating the main shaft 3A. These motors 51 to 55 are servo motors, and are provided with encoders 51a to 55a for detecting the rotational positions of the motors 51 to 55, respectively. The encoder 55a provided in the magazine motor 55 corresponds to the rotation position detecting means.

  The drive circuits 41 to 45 receive the movement command amount from the CPU 31 and output a drive current corresponding to the movement command amount to the motors 51 to 55. The drive circuits 41 to 45 receive position feedback signals from the encoders 51a to 55a and perform position feedback control. Further, the input / output interface 35 is connected to the display 56 via a CRT drive circuit 46.

  The CPU 31 calculates the actual rotation position (magazine shaft position) of the tool magazine 10 based on the rotation position of the magazine motor 55 detected by the encoder 55a and the gear ratio of the speed reducer 15. Similarly, the CPU 31 determines the rotation position (magazine indexing) of the tool magazine 10 based on the rotation position of the magazine motor 55 indicated by the movement command amount for the magazine drive circuit 45 and the gear ratio of the speed reducer 15. (Specified position) is calculated.

  The ROM 32 has a main control program for causing the machining program of the machine tool 1 to function, a control program for excessive deviation error detection control shown in FIG. 4, a control program for magazine axis operation stop processing shown in FIG. 5, and a magazine axis shown in FIG. It stores a control program for recovery processing after the operation stops. The RAM 33 stores a deviation counter overflow value, which is an overflow value of the deviation amount between the actual rotation position of the tool magazine 10 and the index designation position of the tool magazine 10, a magazine axis position deviation amount allowable ratio, and the like.

  The magazine shaft position deviation amount allowable ratio and the deviation counter overflow value are set in advance by the manufacturer before the machine tool 1 is shipped, and based on the magazine shaft position deviation amount allowable ratio and the deviation counter overflow value, A threshold for an excessive deviation amount error, which will be described later, can be set.

Next, deviation amount excessive error detection control executed by the control device 30 will be described based on the flowcharts of FIGS. 4 and 5. In the figure, Si (i = 1, 2,...) Indicates each step.
This deviation amount excessive error detection control is executed by the control device 30 when the tool changer 2 changes the tool. First, the rotation position detection signal transmitted from the encoder 55a to the magazine drive circuit 45, the movement command amount of the magazine motor 55 transmitted from the CPU 31 to the magazine drive circuit 45, the deviation counter overflow value from the RAM 33, and the magazine axis position deviation amount allowable ratio, etc. Are read (S1).

  Next, the position deviation amount of the magazine shaft 14 is calculated (S2). Specifically, it is calculated from the difference between the actual rotation position of the magazine motor 55 and the rotation position indicated by the movement command amount. A threshold relating to an excessive deviation amount error is calculated by multiplying the deviation counter overflow value by the magazine axis position deviation amount allowable ratio / 100, and it is determined whether or not the magazine axis position deviation amount is larger than this threshold value. If the magazine axis position deviation amount is larger than the threshold value (S3; Yes), it is determined that an alarm due to an excessive deviation amount error has occurred (S4), and the process proceeds to S5. However, when the magazine axis position deviation amount is smaller than the threshold value or when the magazine axis position deviation amount is the same value as the threshold value (S3; No), the process proceeds to S1.

When the control device 30 executes the magazine axis operation stop process in S5, the process proceeds to S10.
As shown in the timing chart of FIG. 6, the amount of current supplied from the magazine drive circuit 45 to the magazine motor 55 is reduced by a command from the CPU 31 (the alarm generation signal is turned on), and the rotation speed of the magazine motor 55 is kept constant. (S10). When the rotation speed of the magazine motor 55 is almost stopped (50 rpm or less) (S11; Yes), after the holding brake 55b of the magazine motor 55 is operated by a command from the CPU 31 (holding brake excitation signal is turned on). (S12), the timer is started (S13).

  When 300 msec has elapsed since the holding brake 55b was activated (S14; Yes), the magazine motor 55 is de-energized (de-energized) in response to a command from the CPU 31 (the motor excitation signal is turned on and the holding brake 55b signal is turned on). To do. The magazine drive circuit 45 detects that the magazine motor 55 is in a non-excited state, and activates the dynamic brake of the magazine motor 55 (S15). Thereafter, the timer is stopped (S16), and this process is terminated.

  Next, recovery processing after stopping the magazine shaft when an excessive deviation error is detected will be described based on the flowchart of FIG. In the figure, Si (i = 20, 21...) Indicates each step. This process is started when the power of the machine tool 1 is turned on after the magazine shaft 14 is stopped when an excessive deviation amount error is detected. First, the stop position (magazine shaft position) of the magazine shaft 14 calculated based on the rotation position of the magazine motor 55 detected by the encoder 55a and the gear ratio of the speed reducer 15 is acquired (S20). Next, the control device 30 determines whether or not the magazine axis position matches the magazine index designation position. If they match (S21; Yes), the control device 30 determines that an alarm has not occurred, and the process ends.

  On the other hand, if they do not match (S21; No), the control device 30 determines that an alarm has occurred (S22), and the operator performs a recovery operation on the control device 30 (S23). This process ends.

Next, the operation and effect of the machine tool 1 described above will be described.
In this machine tool 1, the magazine shaft position deviation amount may increase when the torque of the magazine motor 55 is insufficient due to an increase in the viscosity of the lubricating grease in the speed reducer 15 at a low temperature. When the magazine shaft position deviation amount exceeds a threshold value related to an excessive deviation amount error, the control device 30 controls the magazine motor 55 to decelerate. When the rotation speed of the magazine motor 55 becomes 50 rpm or less, the holding brake 55b is operated. After 300 msec from the operation of the holding brake 55b, the control device 30 sets the magazine motor 55 in a non-excited state to operate the dynamic brake.

  Thus, the control device 30 calculates the magazine shaft position deviation amount calculated based on the difference between the actual rotation position of the magazine motor 55 and the rotation position indicated by the movement command amount and the speed ratio of the speed reducer 15. When the deviation exceeds the predetermined threshold value, the magazine motor 55 is decelerated and controlled to stop. Therefore, when the deviation amount becomes excessive, the magazine motor 55 is gently stopped to rotate the tool magazine 10. It can be stopped gently. Therefore, since a large inertia force does not act on the tool stored in the tool magazine 10, it is possible to prevent the tool from falling.

  In addition, since the control device 30 operates the holding brake 55b when the rotation speed of the magazine motor 55 is almost stopped (50 rpm or less), it reliably prevents the tool stored in the tool magazine 10 from dropping. be able to.

  Since the threshold value is set based on a deviation counter overflow value that is an overflow value of the magazine axis position deviation amount and a magazine axis position deviation amount allowable ratio, a value lower than the deviation counter overflow value can be set as the threshold value. it can. Thereby, since the abnormality of the magazine motor 55 and the reduction gear 15 can be discovered at an early stage, the safety at the time of tool exchange can be improved markedly.

Next, a modified example in which the above embodiment is partially modified will be described.
1] The operator may be able to input the magazine axis position deviation amount allowable ratio via the keyboard 36. In this case, based on the magazine shaft position deviation amount allowable ratio and the deviation counter overflow value, the operator can freely set a threshold value regarding the deviation amount excessive error.

1 is a perspective view of a spindle head and a tool changer of a machine tool according to an embodiment of the present invention. FIG. 4 is a side view of the spindle head and the tool changer of the machine tool in a state where only the tool changer has a cross section and the right frame is removed. It is a block diagram which shows the control system of a machine tool. It is a flowchart of a deviation amount excessive error detection control program. It is a flowchart of a control program of magazine axis operation stop processing. It is a timing chart of magazine axis operation stop processing at the time of deviation amount excessive error detection. It is a flowchart of the recovery process after a magazine axis operation stop at the time of the deviation amount excessive error detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Machine tool 2 Tool changer 3A Spindle 10 Tool magazine 30 Controller 55 Magazine motor 55a Encoder 55b Holding brake

Claims (3)

A tool magazine that stores a plurality of tools, a servo motor that has a holding brake and rotates the tool magazine in response to a command from the numerical controller, and includes a tool changer that changes the tool with respect to the spindle. In machine tools,
The tool changer comprises a rotation position detection means for detecting the rotation position of the servo motor,
The numerical control device has a deviation amount between the rotation position of the servo motor detected by the rotation position detecting means and the rotation position of the servo motor indicated by a command value commanded to the servo motor from the numerical control device. A machine tool, wherein when the predetermined threshold value is exceeded, the holding brake is operated for a predetermined time while performing deceleration control of the servo motor, and after the predetermined time has elapsed, the servo motor is operated in a non-excited state.   2. The machine tool according to claim 1, wherein the predetermined threshold is set based on a deviation counter overflow value that is an overflow value of the deviation amount and a deviation amount allowable ratio.   3. The machine tool according to claim 1, wherein the numerical control device operates the holding brake when a rotation speed of the servo motor is almost stopped. 4.