JPH11277356A - Tool replacement device for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten cycle time required by tool replacement operations. SOLUTION: A tool replacement arm is provided, which performs replacement operations between each tool mounted to a spindle and each tool housed in a tool magazine, and a tool replacement cam is also provided, which actuates the tool replacement arm. A driving motor for driving the tool replacement cam is provided, and concurrently, an original point sensor is provided, which detects that the tool replacement cam is in the original point zone where the rotary angle of the cam does not contribute to a cam action at all. One rotation of the tool replacement cam from the original point zone back to the same original point zone, allows a tool replacement action to be processed. A control device allows the driving motor (tool replacement cam) to be accelerated from its starting condition up to first rotation speed Vh set in advance, which allows the cam to be drivingly rotated, and when timer time T has elapsed, the cam is decelerated clown to second replacement speed Vs set in advance, which allows the cam to be decelerated and suspended. Cycle time can thereby be shortened by the period of time made higher in speed than first rotation speed Vh.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool changing device for a machine tool, which changes a tool attached to a main shaft of a machine tool by operating a tool changing arm by a tool changing cam.

[0002]

A machine tool such as a machining center includes a tool changing device for automatically changing tools between a spindle and a tool magazine. Such a tool changing device includes a tool changing arm which has gripping portions at both ends and is turned at the center, a tool changing cam for operating the tool changing arm, and a drive for rotating and driving the tool changing cam. There is one configured with a motor or the like.

In this apparatus, the tool changing cam is rotated once by the drive motor to move the tool changing arm at the standby position to the tool holding position, and the tools of the main spindle and the tool magazine are respectively held by the two holding portions. The step of gripping, the step of rotating the tool change arm about 180 degrees therefrom to change the position of both tools, and the step of mounting the tools on the spindle and the tool magazine respectively and returning the tool change arm to the standby position It is performed continuously.

At this time, in order to control the rotation of the tool changing cam, that is, to stop the rotation when the rotation angle of the tool changing cam is in the origin area (the area where the tool changing arm is located at the standby position), FIG. As shown in FIG. 5, a rotating disk 33 which rotates integrally with the tool changing cam and has a slit 33a in an angular range corresponding to the origin region is provided.
An origin sensor including a photo sensor (not shown) for detecting the slit 33a of the rotating disk 33 is provided.

The detection signal of the origin sensor is input to a control circuit for controlling the drive motor, and the drive motor (and, consequently, the tool changing cam) is provided with a so-called equal leg as shown in FIG. It is driven in a trapezoidal speed pattern. That is, when a rotation command is output (time t0), the drive motor is accelerated and rotated at the rotation speed v1. When the rotating disk 33 makes substantially one rotation and the origin sensor relatively enters the slit 33a (time t1), the rotation command is stopped based on the detection signal of the origin sensor and deceleration is started. The drive motor is stopped while the origin sensor detects the slit 33a.

In such a tool changer, it is desirable to reduce the tact time as much as possible. To achieve this, it is conceivable to increase the rotation speed of a drive motor (cam for tool change). However, FIG.
As shown in the figure, the rotation speed of the drive motor is simply set to v1
When the speed is increased from v2 to v2, the tool changing cam cannot be stopped in the origin region at the time of deceleration and stop, which causes a problem of so-called overrun.

Therefore, in order to solve such a problem, another sensor is provided so as to detect the slit 33a a little before the detection of the origin sensor, and based on a detection signal of the sensor. To start deceleration. However, this increases the number of sensors and increases the cost. As another method, it is conceivable to widen the slit 33a slightly before the origin area and start deceleration just before entering the original origin area. However, this makes it impossible to correctly detect that the tool-changing cam is in the home region, and may stop before the home region when the drive motor is rotated at a low speed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to increase the number of sensors and to reliably detect that a tool changing cam is located at an origin area, but to perform a tool changing operation. An object of the present invention is to provide a tool changer for a machine tool that can reduce the tact time.

[0009]

In order to achieve the above object, a tool changing device for a machine tool according to the present invention comprises a tool changing cam for operating a tool changing arm by rotary driving, and a rotating tool changing cam. A drive motor to be driven, and detection means for detecting that the rotation angle of the tool change cam is in an origin region that does not contribute to the operation of the tool change arm,
Motor control means for controlling the drive motor to rotate the tool changing cam in the origin area substantially one rotation and stop again in the origin area based on the detection of the detection means, The means is configured to rotate the tool changing cam at a high first rotation speed at the beginning of rotation start, and to rotate at a second rotation speed lower than the first rotation speed after elapse of a predetermined timer time. (The invention of claim 1).

Here, when decelerating and stopping the tool changing cam, which is driven to rotate at a certain speed, the time required for stopping and, moreover, the amount of rotation from the start of deceleration to the stop of the tool changing cam is the rotation just before the deceleration. Corresponds to speed. Therefore, in order to stop the tool changing cam in the origin region based on the detection of the detecting means during the rotation of the tool changing cam, the rotation speed immediately before the start of the deceleration is required from the start of the deceleration to the stop. The speed may be set so that the tool changing cam does not overrun the origin area within the time.

According to the above configuration, the tool control cam is rotated by the motor control means at the high first rotation speed at the beginning of the rotation start, and after the fixed timer time elapses, the second rotation becomes lower than the first rotation speed. Speed is reduced to speed. At this time, the second rotation speed is set to such a speed that the tool changing cam does not overrun the origin region, and a certain timer time is set before the deceleration is started.
Even when the rotation speed is increased, the tool changing cam can be stopped in the origin region. Thereby, the first
The time required for one rotation of the tool changing cam can be reduced by an amount corresponding to the increased rotation speed. In addition, the number of sensors does not increase, and the detection means can reliably detect that the tool changing cam is in the origin area.

In this case, the first rotation speed may be changed in accordance with the type of tool to be replaced, and the timer time may be changed in accordance with the change (the invention of claim 2). According to this, the first rotation speed can be set to an appropriate speed according to the type of the tool, for example, by lowering the rotation speed for a heavy tool, and the appropriate timer time can be set accordingly. It can be.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. First, FIG. 3 shows an external configuration of a main part of a machine tool (machining center) 1. Here, a column 3 is provided on the base 2 so as to extend upward. A linear guide 4 extending in a vertical direction is provided on a front surface of the column 3, and a headstock 5 is provided along the linear guide 4. Are supported to be able to move up and down.

The column 3 is provided with a Z-axis motor 6 and a ball screw mechanism (only the ball screw 7 is shown) for freely moving the headstock 5 in the vertical direction. At the front of the base 2, a work (not shown) is set, and an XY table 8 is provided for freely moving the work in the XY directions.

The headstock 5 is provided with a machining head 9, a rotary tool magazine 10 and a tool changer 11 according to the present embodiment. The machining head 9 has a spindle 12 at a lower portion thereof and a spindle motor 13 for rotating the spindle 12 at an upper portion thereof. A tool 14 is provided on the spindle 12.
Are detachably attached.

Thus, the machining head 9 rotates the tool 14 attached to the spindle 12 while rotating the Z-axis motor 6.
The work set on the XY table 8 is moved in the horizontal direction at the same time, whereby the work is performed on the work. At this time, the XY table 8, the Z-axis motor 6, the spindle motor 13 and the like are controlled by an NC control device (not shown).

Although a detailed illustration and description are omitted, the tool magazine 10 has a plurality of tool pots (not shown) capable of storing tools 14 arranged in a ring shape. Tool pot (tool 14)
Is positioned at the lowermost tool access position. The tool changing device 11 includes a tool 14 housed in a tool pot at a tool access position,
(If the tool 14 is in only one of them, the tool 14 is transferred to the other). Hereinafter, the tool changing device 11 according to the present embodiment will be described.

As shown in FIGS. 2 and 4, the tool changing device 11 includes a tool changing arm 16 for performing a tool changing operation.
(See FIG. 4), the tool change arm 16
, A drive motor 18 for rotating and driving the cam 17, and a drive motor 1
8 is provided with a control device 19 (see FIG. 2) as a motor control means for controlling the motor 8.

As shown in FIG. 4, the tool change arm 16 is provided at an intermediate portion between the tool access position of the tool magazine 10 and the spindle 12 and provided at a lower portion of the headstock 5. 20, gripping portions 21 and 21 for gripping and transporting the tool 14 are provided at both ends thereof in a point-symmetric manner. The arm support 20 is connected to a lower end of a pivot 22 that is rotatably and vertically movable within the headstock 5.

The drive motor 18 is a geared motor in which a speed reducer is built in an induction motor, and is mounted downward on a top surface of the headstock 5 via a bracket 23. The tool changing cam 17 has a cylindrical shape that is long in the up-down direction, and shaft portions 17a at both upper and lower ends thereof are rotatably supported via bearings 38 and are disposed in the headstock 5. The shaft 17a at the upper end of the tool changing cam 17 is connected to the output shaft 18a of the drive motor 18 via a coupling 24.

The tool changing cam 17 includes a parallel cam 25, a first cam groove 26, and a second cam groove 2 in order from the top.
7, a third cam groove 28 is provided. Although the detailed description is omitted, the parallel cam 25 is provided for rotating the turning shaft 22 via a driven roller 29 or the like, and the parallel cam 25 is rotated during one rotation of the tool changing cam 17 in the arrow A direction. , The rotating shaft 22 (and thus the tool change arm 1)
6) is rotated (turned) by 180 degrees in the direction of arrow B.

The first cam groove 26 is provided to swing a swing member 30 (only a part is shown) to operate a tool release pin (not shown) provided on the main shaft 12. . The second cam groove 27 is connected to the turning shaft 22 and thus the tool changing arm 1 via a swing lever 31.
6 is provided to move up and down. The third cam groove 28 rotates the tool changing arm 16 by a predetermined amount with respect to the arm support 20 via a gear mechanism 32 or the like (reciprocating operation between a standby position and a tool changing position described later).
It is provided for the purpose.

With the rotation of the tool changing cam 17 by one rotation, the tool changing arm 16 operates as follows to change the tool. In other words, the tool change arm 16 normally rotates the gripping portions 21 and 21 rearward in the rotational direction (opposite to the arrow B) from the tool 14 of the main spindle 12 and the tool 14 positioned at the tool insertion / removal position of the tool magazine 10, respectively. ) In the standby position, which is slightly separated from the standby position. At this time, in the tool magazine 10,
The tool 14 to be replaced has been moved to the tool access position in advance.

When the tool changing cam 17 rotates, first, the tool changing arm 16 pivots by a small amount in the direction of the arrow B to move to the tool changing position.
The tool 1 grips the tool 14 attached to the main shaft 12 and the tool located at the tool entry / exit position of the tool magazine 10, respectively. Next, from that state, the tool change arm 1
6 descends integrally with the turning shaft 22, and the two tools 14 are respectively extracted. When removing the tool 14, the tool release pin of the main shaft 12 is operated.

Subsequently, the turning shaft 22 is rotated in the direction of arrow B, and the tool changing arm 16 is turned by 180 degrees.
The positions of the two tools 14 and 14 held by the tools 1 and 21 are exchanged. After that, the tool change arm 16 moves up,
A new tool 14 is mounted on the spindle 12 and the tool 14 previously attached to the spindle 12 is attached to the tool magazine 10.
And the grips by the grippers 21 and 21 are released. Thereafter, the tool change arm 16 is moved to the arm support 20.
, A slight amount of turning movement in the direction opposite to the arrow B and the return to the standby position.

The operation of the above-mentioned tool change and the rotation of the tool change cam 17 are performed by controlling the drive motor 18 by the control device 19. At this time, the operation of one tool change is performed by the tool change arm 16.
Is performed by rotating the tool changing cam 17 substantially one turn until the tool changing cam 17 is returned to the waiting position substantially half a turn from the standby position which does not contribute to the changing operation. At one time, the tool change arm 16 is positioned at the standby position, and the origin area thereof is set to an angle range of, for example, about 40 ° in this case.

As shown in FIGS. 2 and 4, the coupling 24 is provided with a detecting means for detecting that the rotation angle of the tool changing cam 17 is in the origin region. In the present embodiment, the detecting means includes a rotating disk 33 fixedly attached to the coupling 24 and an origin sensor 34 attached to the bracket 23.

As shown in FIG. 5, the rotating disk 33 has a slit 33a in the outer peripheral portion thereof in an angular range corresponding to the origin region, and the tool changing cam 17 is provided.
It is designed to rotate integrally with. On the other hand, the origin sensor 34 is composed of, for example, a transmission type photo sensor, and as is well known, a light projecting element and a light receiving element are arranged opposite to each other on both ends of a U-shaped holder, and The outer peripheral portion of the rotating disk 33 is provided so as to pass therethrough. Therefore, when the slit 33a exists between the light emitting element and the light receiving element, the origin sensor 34 outputs an ON signal to detect that the tool changing cam 17 is in the origin area. Has become.

As shown in FIG. 2, the controller 19 comprises a controller 35 comprising a microcomputer and the like,
6. It comprises an inverter 37 for driving the drive motor 18 at a variable speed. The detection signal of the origin sensor 34 is input to the controller 35. As will be described later, the controller 35 is configured to output a rotation command signal or a rotation speed command signal to the inverter 37 and cut off the signal based on the detection signal of the origin sensor 34. . The timer 36 counts a preset timer time T from the time when the controller 35 outputs the rotation command signal, and outputs a speed change command signal when the timer time T has elapsed. It has become.

At this time, as shown in FIG. 1, a first rotation speed Vh and a lower second rotation speed Vs are set in the controller 35 in advance. The rotation speed command of the first rotation speed Vh is output to the inverter 37, and when the speed change command signal of the timer 36 is input, the rotation speed command is changed to the second rotation speed Vs.
To be changed to And the inverter 37
When the rotation command signal is received from the controller 35 (time t0), the drive motor 18 is accelerated from the stopped state to the first rotation speed Vh and maintained at that speed. After the timer time T has elapsed, the rotation speed command is changed. Then, the rotation speed of the drive motor 18 is reduced to the second rotation speed Vs. Then, when the rotation command signal of the controller 35 is cut off (time t1), the drive motor 18 is decelerated and stopped.

Next, the operation of the above configuration will be described. In the tool changer 11 described above, the driving motor 18 drives the tool changing cam 17 substantially one rotation in the direction of arrow A from the state of being in the origin area, and is stopped again in the origin area. As described above, the tool exchange operation is performed in which the tool exchange arm 16 at the standby position exchanges the tool 14 between the spindle 12 and the tool magazine 10 and returns to the standby position again.

At this time, the controller 35 for controlling the drive motor 18 detects when the tool changing cam 17 has entered the origin area by the origin sensor 34 in order to stop the tool changing cam 17 in the origin area. That is, the rotation command signal is cut off when the ON signal is input from the origin sensor 34 (time t1 shown in FIG. 1). Then, the drive motor 18 and thus the tool changing cam 17 are
The motor decelerates from the time t1 and stops in the origin area. Note that the control device 19 (controller 35) controls the origin sensor 34 when the drive motor 18 stops.
Is turned on.

Here, when decelerating and stopping the drive motor 18 (the tool changing cam 17), which is rotationally driven at a certain speed, the time required for the stop, and consequently, the rotation of the tool changing cam 17 from the start of the deceleration to the stop. The amount corresponds to the rotation speed immediately before the deceleration of the tool changing cam 17 and thus the drive motor 18. Therefore, in order to stop the tool changing cam 17 in the origin region, the rotation speed (second rotation speed Vs) immediately before the start of the deceleration is adjusted by the tool changing cam 17 within the time required from the start of the deceleration to the stop. The second rotation speed Vs is set in advance to such a speed that the tool changing cam 17 does not overrun the origin region.

As described above, if the second rotation speed Vs is set immediately before the start of deceleration, the rotation speed may be higher than the second rotation speed Vs before that (at the beginning of rotation). Since there is no problem in stopping the tool changing cam 17, the first rotation speed Vh is set higher than the second rotation speed Vs and an appropriate speed in advance, and a timer is set in accordance with the first rotation speed Vh. The time T is set in advance. Thus, the drive motor 18 (and thus the tool changing cam 17) is driven by the control device 19 in a speed pattern as shown in FIG.

According to this embodiment, the rotation speed of the drive motor is kept constant (the speed v1 shown in FIG. 6) as in the prior art.
), The first rotation speed Vh can be increased, and the time required for one rotation of the tool changing cam 17, that is, the time required for the tool changing operation can be shortened. Obtainable. By the way, in the related art (see FIG. 6), the tact time (time from time t0 to t1) is 0.7 seconds, whereas in the present embodiment, the tact time (time from time t0 to t1) is used. Was reduced to 0.5 to 0.6 seconds.

Moreover, in the present embodiment, only one origin sensor 34 for detecting that the tool changing cam 17 is in the origin region is provided, and the number of sensors does not increase. Further, the slit 33a of the rotating disk 33 does not need to be unnecessarily widened, and the slit 33a corresponding to the origin area can be used. Therefore, regardless of the rotation speed of the tool exchange cam 17, the tool exchange cam 17 Can be reliably detected in the origin region.

In the above embodiment, the first rotation speed Vh
, The timer time T, and the second rotation speed Vs are set to constant values, however, the speed and the timer time may be changed according to the type (weight, etc.) of the tool 14 to be replaced. According to this, for example, a heavy tool 1
In the case of No. 4, a more appropriate speed and timer time can be set according to the type of the tool 14, such as lowering the rotation speed, and more precise and smooth control can be performed.

In addition, the mechanical structure of each part such as a tool changing arm and a tool changing cam can be variously modified. The detecting means is not limited to a transmissive photo sensor, but may be various sensors. The present invention can be implemented with appropriate changes without departing from the gist of the invention, such as adopting a switch or the like, and further changing the rotation speed in three or more steps.

[0039]

As is apparent from the above description, according to the tool changing device for a machine tool of the present invention, a tool changing cam for causing a tool changing arm to execute a tool changing operation is provided at a high speed at the beginning of rotation. Is rotated at a first rotation speed, and after a certain timer time elapses, it is rotated at a second rotation speed lower than the first rotation speed. Therefore, the number of sensors is increased and the tool changing cam can be used. This is an excellent practical effect that the tact time of the tool changing operation can be reduced while reliably detecting that it is in the origin region.

[Brief description of the drawings]

FIG. 1 illustrates an embodiment of the present invention and illustrates a relationship between a rotation speed of a drive motor over time and an ON / OFF state of an origin sensor at that time.

FIG. 2 is a diagram schematically showing an electrical configuration related to control of a drive motor.

FIG. 3 is a perspective view of a main part of the machine tool.

FIG. 4 is a longitudinal sectional view showing a configuration of a main part of the tool changing device.

FIG. 5 is a plan view of a rotating disk.

FIG. 6 is a diagram corresponding to FIG. 1 showing a conventional example.

FIG. 7 is a diagram corresponding to FIG. 6 when the rotation speed is increased.

DESCRIPTION OF THE SYMBOLS In the drawings, 1 is a machine tool, 10 is a tool magazine, 11 is a tool changing device, 12 is a spindle, 14 is a tool, 16 is a tool changing arm, 17 is a tool changing cam, 18 is a drive motor, 1
9 is a control device (motor control means), 33 is a rotating disk, 3
3a is a slit, 34 is an origin sensor (detection means), 35
Denotes a controller, 36 denotes a timer, and 37 denotes an inverter.

Claims (2)

[Claims] 1. A tool for exchanging a tool attached to a main shaft of a machine tool by an operation of a tool exchanging arm, comprising: a tool exchanging cam for operating the tool exchanging arm by rotational driving; and rotating the tool exchanging cam. A drive motor to be driven; detecting means for detecting that the rotation angle of the tool changing cam is in an origin area which does not contribute to the operation of the tool changing arm; and Motor control means for controlling the drive motor so as to rotate the tool changing cam substantially once and stop at the origin area again, and the motor control means sets the tool changing cam at an initial rotation start time. Is configured to rotate at a high first rotation speed and to rotate at a second rotation speed lower than the first rotation speed after a certain timer time has elapsed. Tool changer of the machine tool, characterized by being. 2. The machine tool according to claim 1, wherein the first rotation speed is changed in accordance with a type of a tool to be replaced, and the timer time is also changed in accordance with the change. Tool changer.