JPH0134745B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an automatic tool changer for a machine tool,
In particular, the present invention relates to an indexing mechanism for an automatic tool changer that indexes a tool magazine using rotation of a spindle motor and uses balls and springs for final positioning.

[Conventional technology]

The automatic tool changer (hereinafter referred to as ATC) for machine tools is disclosed in Japanese Patent Application Laid-Open No. 132874/1983 and Japanese Patent Application Laid-Open No. 1983-
It is publicly known as described in Publication No. 53373,
A tool magazine carrying a plurality of tools is rotated to index the desired tool position.

[Problem to be solved by the invention]

The above-mentioned Japanese Patent Application Laid-open No. 53-132874 employs a ratchet feed mechanism that can rotate the tool magazine one tool pitch at a time by using the reciprocating motion of the machine tool's Y-axis feed motor to index the tool magazine. are doing. ATC requires that the selected tool be positioned precisely in alignment with the spindle. However, although the mechanical ratchet feed mechanism can move a certain amount in one direction, the amount of feed is not necessarily accurate, and therefore requires accurate positioning means. The publication employs a positioning mechanism in which grooves are provided in the fixed part of the tool magazine and balls are arranged in the rotating part.

The above-mentioned Japanese Patent Application Laid-Open No. 54-53373 discloses indexing a tool magazine using a spindle motor for rotating the spindle. According to this method, the transmission path from the spindle motor to the tool magazine can be simplified, the amount of rotation of the spindle motor can be made to correspond to the amount of rotation of the tool magazine, and a position coder is provided to detect the position of the tool magazine. If the spindle motor is controlled according to the signal, the tool magazine can be accurately positioned.

However, in an indexing device that transmits the rotation of the spindle motor to the tool magazine, the spindle motor is rotated at high speed during machining, which is the main operation, and relatively slowly when indexing the tool magazine, which is a sub-operation. It is necessary to operate at rotational speed. When changing tools, it is necessary to operate at a slow rotational speed and decelerate as the tool magazine approaches the target position, which takes time and places a large load on the spindle motor. Ta. For this reason,
When rotating the tool magazine, it was necessary to avoid applying as much load to the spindle motor as possible.

[Means to solve the problem]

To achieve the above object, the indexing and positioning mechanism of an automatic tool changer according to the present invention comprises a rotating part that carries a tool and is rotatable about a predetermined axis, and a rotating part that is maintained in a fixed position relative to the rotating part. a tool magazine having a fixed part; a means for detecting a rotational position of the rotating part of the tool magazine about the axis; and a rotation of a spindle motor driven in accordance with an output of the detection means for transmitting the rotation to the tool magazine. a plurality of shallow grooves corresponding to the pitch of the tools are provided on a circumference centered on the axis of the fixed part of the tool magazine, and a plurality of shallow grooves are provided in the rotating part of the tool magazine facing the shallow grooves. A plurality of guide grooves are provided on the same circumference as the shallow groove, and a ball is inserted into the guide groove, and the ball has a size that partially fits into the shallow groove, and when the ball enters the shallow groove. At least half of the ball is in the guide groove, and a spring is provided in the guide groove to press the ball toward the shallow groove, so that the ball is inserted into the guide groove when the tool magazine is indexed by the spindle motor. It is characterized in that it fits into the shallow groove.

[Operation] In the above configuration, the position of the tool magazine can be determined only by the spindle motor by driving the spindle motor while detecting the position of the tool magazine using a detection means such as a position coder. can. The spring-loaded balls roll along the opposing surfaces of the stationary part of the tool magazine as it rotates and enter shallow grooves in the opposing surfaces when the tool magazine comes to rest. Therefore, the time constant during deceleration of the spindle motor can be reduced, and the time until it stops can be shortened. However, at the beginning of indexing the tool magazine, the ball escapes from the shallow groove, so the load on the spindle motor increases.

〔Example〕

The present invention will be described below based on embodiments with reference to the drawings. FIG. 1 is a diagram showing the entire ATC device according to the present invention, in which a pair of gears 46,
48 shows the state where the tool is separated and the tool is gripped by the spindle at the same time. Figure 2 shows a pair of gears 4 used to drive the tool magazine when changing tools.
6 and 48 are diagrams illustrating the engagement and the tool being removed from the main shaft at the same time.

In the figure, 2 indicates the main shaft, 4 indicates the main shaft head, and the main shaft 2
is rotatably held by the spindle head 4, and is driven by the spindle motor 6 via a belt. A position coder 8 is also rotatably connected to the main shaft 2, and the main shaft motor 6 and position coder 8 are electrically connected to a control device NC10 and are controlled by commands from the NC10.

Spindle 2 in the vertical axis direction (hereinafter referred to as the Z-axis direction)
In order to drive the spindle head 4 to the nut 12,
It is connected to a Z-axis feed motor 16 via a feed screw 14. The Z-axis feed motor 16 is connected to an X-axis motor 22 and a Y-axis motor 24 that drive a table 20 carrying a workpiece 18 in the horizontal X-axis and Y-axis directions.
It is electrically connected to the NC 10 and drives the spindle 2 and table 20, respectively, according to commands from the NC 10.

A slider 30 is slidably supported on the spindle head 4, and a support member 32 extends from the spindle head 4.
A spring 34 is tensioned between the slider 30 and the slider 30. Due to the action of the spring 34, the slider 30 is normally in integral relationship with the spindle head 4, and when the spindle head 4 is raised in the Z-axis direction, the slider 30 comes into contact with a stopper 36 fixed to the frame 38.

The slider 30 has a shaft 41 for supporting the tool magazine.
is fixed, and the tool magazine 40 is rotatably supported by this shaft 41. The tool magazine 40 holds a plurality of tools 42 at regular intervals on its circumference. These tools 42 are provided with an arbor 44 and are adapted to be fitted into the tapered portion of the main shaft 2.
The spindle 2 and the tool magazine 40 have a relative positional relationship; the tool 42 is held by the spindle 2 during machining, and the Z of the spindle 2 and the tool magazine 40 is held during tool exchange.
The tool 42 is held in the tool magazine 40 by the relative movement in the axial direction, and the subsequent tool magazine 4
One end of the tool 42 does not come into contact with the main shaft 2 during the zero rotation, and a new tool 42 indexed by the rotation of the tool magazine 40 is placed on the same line as the main shaft.

Further, a gear 46 is fixed to the main shaft 2 and a gear 48 is fixed to the magazine 40, and these pair of gears 4
6 and 48 are separated during machining as shown in FIG. 1, and are engaged during tool exchange as shown in FIG.

FIG. 3 is a cross-sectional view with some details omitted of the area of the tool magazine 40 shown by A in FIG. 2.
In the figure, 41 is a support shaft of the tool magazine 40 fixed to the slider 30 mentioned above, and this support shaft 41
A circular plate 50 is fixed to the circular plate 50, and the circular plate 50 has a circumferential convex portion 50', and a tool 4 is attached to the convex portion 50'.
A shallow groove 52 is provided corresponding to the pitch where 2 is to be attached. The support shaft 41 and the circular plate 50 form a fixed part for the rotation of the tool magazine 40. on the other hand,
Rotating parts of the tool magazine 40 (hatched in the diagram)
A guide groove 54 is provided opposite to the shallow groove 52 on the same circumference as the convex portion 50' provided with the shallow groove 52, and a ball 56 and a spring 58 are inserted into the guide groove 54, and by the action of the spring 58. The ball 56 is pressed against the shallow groove 52. The number of guide grooves 54 is 52.
may be equal to or less than the number of

FIG. 4 is a sectional view of the shallow groove 52, guide groove 54, ball 56, and spring 58 shown in FIG. 3, viewed from the radial direction of FIG. In this example, the shallow groove 52 is a V-groove, and the ball 56 is large enough to partially fit into the shallow groove 52, and at least half of the ball 56 enters the guide groove 54 when it enters the shallow groove 52. It's starting to happen. The balls 56 are adapted to fall into the shallow grooves 52 during indexing of the tool magazine 40.

Next, the operation of the ATC indexing mechanism of the present invention will be explained. During machining, the gears 46 and 48 are not engaged, as shown in FIG. 1, and the tool magazine 40 does not rotate even if the spindle motor 6 is driven. The slider 30 can move integrally with the spindle head 4 in the Z-axis direction, and moves the desired tool 42.
is gripped by the main spindle 2, and machining is performed based on commands from the NC 10. The Z-axis feed motor 16 transmits feed in the Z-axis direction to the spindle head 4 supporting the spindle Z within a predetermined range with a predetermined origin as the upper limit. When changing tools, the spindle head 4 is raised to the origin, and during this time the spindle motor 6 orients the spindle 2. As the spindle head 4 is further raised by the Z-axis feed motor 16, the tool arbor 44 is loosened from the taper gripping portion of the spindle 2, and then the slider 30 supporting the tool magazine 40 comes into contact with the stopper 36. At this position, the slider 30 stops, and only the spindle head 4 further rises. During this time, the arbor 44 of the tool 42 is removed from the tapered part of the main shaft 2, and at the same time, the gear 48 fixed to the tool magazine 40 is removed.
A gear 46 fixed to the main shaft 2 meshes with the gear 46. Here, the main shaft motor 6 is rotationally driven, and the position coder 8 indexes the tool magazine 40 while detecting the rotation of the main shaft motor 6.

When indexing the tool magazine 40 by relying only on the drive of the spindle motor 6, the weight of the tool magazine 40 carrying a large number of tools 42 usually becomes a large load on the spindle motor 6. When the tool magazine 40, which has a large load inertia, is to be finally positioned, the speed of the spindle motor 6 immediately before it stops is small, and it is necessary to take more time to position the tool magazine 40 with high accuracy. In the present invention, a ball 56 is dropped into a shallow groove 52 and attracted by a spring 58 for the final indexing position of the tool magazine 40. Once the tool magazine 40 has been positioned, the Z-axis feed motor 16 can be driven in the reverse order as described above to return to a state in which machining can be performed.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided means for transmitting the rotation of the spindle motor to the tool magazine, and the ball is inserted into the guide groove provided in the rotating part of the tool magazine and is biased by a spring. of the spindle motor by configuring the spring-biased balls to fall into shallow grooves in the opposing fixed parts, such that the spring-biased balls engage surfaces containing the shallow grooves in the opposed fixed parts. Although the load will increase, the time constant during deceleration of the spindle motor can be made smaller and the time until it stops can be shortened. That is, the time constant can be made smaller than the controllable time constant determined by the load until it becomes equal to the acceleration of the balls falling into the plurality of shallow grooves in the fixed part of the tool magazine. In addition, when indexing the tool magazine, the ball biased by the spring engages with the surface containing the shallow groove of the opposing fixed part, which increases the load on the spindle motor. It also functions as an automatic locking device that prevents the tool magazine from rotating if it falls into the shallow groove of the fixed part. In addition, by providing multiple balls in the rotating part that engage with the shallow grooves provided in the fixed part, the forces acting on the tool magazine are better balanced, allowing smooth rotation and positioning for indexing. At the same time, since the positioning force (spring force) per piece can be reduced, wear is also reduced.

[Brief explanation of drawings]

FIG. 1 includes the magazine indexing mechanism of the present invention.
A diagram showing ATC when ATC is present during machining, FIG. 2 is a similar diagram when ATC is during tool exchange, and FIG. 3 is an enlarged sectional view of part A in FIG. FIG. 4 is a cross-sectional view of the groove and ball portion of FIG. 3, viewed from the radial direction. 2...Main shaft, 6...Main shaft motor, 40...Magazine (rotating part), 50...Fixed part, 52...
Shallow groove, 54... Guide groove, 56... Ball, 58
...Spring.

Claims (1)

[Claims] 1. A tool magazine having a rotating part that can carry a tool and rotate about a predetermined axis, and a fixed part that is maintained in a fixed position opposite to the rotating part, and a circle centered around the axis of the fixed portion of the tool magazine, comprising means for detecting a rotational position around the rotational position, and means for transmitting rotation of a spindle motor driven in accordance with the output of the detection means to a tool magazine; A plurality of shallow grooves corresponding to the pitch of the tools are provided on the circumference, and a plurality of guide grooves are provided on the same circumference as the shallow grooves and opposite to the shallow grooves in the rotating part of the tool magazine, and the guide groove a ball is inserted into the guide groove, the ball is sized to partially fit into the shallow groove, and at least half of the ball enters the guide groove when the ball enters the shallow groove; Indexing and positioning of an automatic tool changer, characterized in that a spring is provided inside to press the ball toward the shallow groove so that the ball enters the shallow groove when the tool magazine is indexed by the spindle motor. mechanism.