JPS6131770Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for rotationally driving a workpiece by supporting both centers.

The purpose of this invention is to smoothly and reliably attach the inner hole of the workpiece to the collet in a device having a collet at the tip of the spindle center that expands and grips the inner hole of the workpiece.

When a workpiece is supported by both centers installed on the headstock and tailstock and the rotation of the spindle is transmitted to the workpiece for machining, it is possible to transmit the rotation of the spindle to the outer diameter or end face of the workpiece. When there is a rotary drive point that can be rotated, the workpiece is rotated by gripping this rotary drive point with a normal drive transmission means. In the case of a workpiece of a special shape that does not have a drive point, it cannot be rotationally driven using normal drive transmission means. As a drive device for such a specially shaped workpiece, an inner diameter collect mechanism is provided at the tip of the center on the spindle side, and rotational power can be transmitted to the workpiece by expanding and gripping the workpiece using the inner hole collect mechanism. It is being done. In this device, since the workpiece is rotated with reference to the center, the inner diameter collect mechanism needs to float in the radial direction relative to the spindle center. Conventionally, the spindle center and the collect body were connected by a spline. , the collector body was allowed to float in the radial direction.

However, since there is no function to hold the collector body concentrically with the spindle axis when the collet is unclamped, the tip of the collet hangs down and is displaced from the spindle axis.

The workpiece carried into this collet is carried into the collet by gripping the end face of the workpiece on the inner hole side concentrically with the spindle axis using a carrying device, etc., so that the tip of the collet is displaced from the spindle axis. There was a problem that the end face of the workpiece would come into contact with the tip of the collet, making it impossible to install the workpiece smoothly and reliably.

In addition, coolant may enter the spindle center through the gap between the collet body and the spindle center, causing corrosion of the guide surface that guides the collet body so that it can move in the radial direction, inhibiting the floating action of the collet body. It was hot.

This idea improves the above conventional problem,
The feature is that the collet body, which is inserted into the tip of the spindle center while allowing displacement in the radial direction, is always elastically supported concentrically with the spindle axis, and this elastic support mechanism An object of the present invention is to provide an effective device that also has a sealing function to prevent the intrusion of foreign substances.

Examples of this invention will be described below with reference to the drawings. 1 is a headstock, 2 is a bearing sleeve, 3 is a main shaft rotatably supported by the bearing sleeve 2 and rotationally driven by a drive device (not shown), 4 is tapered fitted to the main shaft 3 and rotates integrally with the main shaft 3 Spindle center, 5
is a tailstock center facing the main spindle center 4 on the same axis, and 6 is a grinding wheel.

In this invention, the spindle center 4 is provided with the following structure. That is, the shaft portion 8 of the collet body 7 is inserted into the axial center hole of the tip of the spindle center 4.
are inserted so as to be freely movable in the radial direction with a gap 11 between them. This collect body 7 has a workpiece W at its tip.
An extended gripping portion 9 is provided which presses onto the inner circumferential surface of the inner hole Wd. This expanded gripping portion 9 is provided with axial grooves 15 at several locations around its circumference, and the grooves 15 are filled with seal rubber. Further, a flange portion 10 is formed at the rear end, and a gap 12 exists between the flange portion 10 and the inner hole of the spindle center 4. A notch 13 is provided on the outer periphery of the flange portion 10, into which a drive key 14 screwed onto the spindle center 4 is engaged, thereby transmitting the rotation of the spindle center 4 to the collector body 7.

As described above, the collet main body 7 is fitted into the spindle center 4 to allow displacement in the radial direction and to rotate integrally in the rotational direction, and the shaft portion 8 is connected to the annular elastic body 1.
6, it is elastically supported concentrically with the axis of the main shaft 3. It is desirable that the annular elastic bodies 16 be disposed at two locations separated by a required distance in the axial direction of the collector body 7. In this case, an auxiliary sleeve 17 having a gap 25 between it and the outer periphery of the shaft portion 8 is inserted in order to maintain the positions of the pair of annular elastic bodies 16 that are spaced apart from each other.

Furthermore, a draw rod 18 that is movable forward and backward in the axial direction is passed through the center of the collector body 7. A tapered tip 19 is formed at the tip of the draw rod 18 for expanding and contracting the expansion grip portion 9 at the tip of the collector body 7.

Although the rear end of the draw rod 18 may be connected to the piston rod 24 of the fluid pressure cylinder via a joint, the following structure is preferable in order to improve the operability of attaching and detaching the main shaft center 4. . That is, an inner hole 27 is provided in the rear end of the spindle center 4 in the axial direction, and the end cap 21 is screwed into the open end of the inner hole 27. Also, inner hole 2
A regulating member 22 serving as a spring receiver and regulating the backward movement of the collector body 7 is screwed onto the inner end of the collector body 7. A flange 20 facing the regulating member 22 is formed at the rear end of the draw rod 18, and a clamping spring 23 is interposed between the flange 20 and the regulating member 22 to keep the draw rod 18 in the backward direction. In other words, the gripper 19 applies an axial movement force in the direction of expanding the expansion grip portion 9. The outer peripheral surface of the flange 20 and the spindle center 4
There is a gap 28 between the draw rod 1 and the inner hole 27 of the draw rod 1.
8 is also displaced. Further, the flange 20 is integrally formed with a protrusion 26 that penetrates the end cap 21 and protrudes to the outside, and is configured to face a piston rod 24 of a fluid pressure cylinder (not shown) for unclamping. According to this structure, the piston rod 24 and the draw rod 18
Since there is no need for connection with the main shaft center 4, the connection means is omitted, and furthermore, the operation of attaching and detaching the spindle center 4 becomes easy.

Next, the operation of this invention will be explained. When mounting the workpiece W, the previously machined workpiece is unclamped, that is, the piston rod 24 moves forward and presses the protrusion 26, the draw rod 18 moves forward against the spring 23, and the workpiece 19 moves forward. The expansion grip portion 9 is released from expansion and is in a contracted state. In this state, the unprocessed workpiece W is carried by the carrying device toward the spindle center 4 so that the extended grip part 9 enters into the inner hole Wd, and the inner peripheral edge of the opening of the inner hole Wd is supported on the tapered surface of the spindle center 4. let At this time, the axis of the workpiece W to be carried in is made to substantially coincide with the axis of the main spindle 3. Therefore, if the collet main body 7 is displaced by its own weight and the extended gripping part 9 is hanging down, it will interfere with the end surface of the inner hole Wd of the workpiece W and smooth and reliable mounting cannot be achieved.
In this invention, the annular elastic body 16 always holds the collector body 7 concentrically with the spindle axis, so that there is no problem of interference as described above, and the collet can be mounted smoothly and reliably. Moreover, since the annular elastic body 16 enables the radial behavioral displacement of the collet body 7 through elastic deformation, the center of the spindle center support surface of the workpiece W supported by the spindle center 4 and the extended gripping portion 9
If there is a deviation between the center of the contact surface and the inner hole Wd, this is absorbed by the radial displacement action of the collector body 7.

Next, after being supported by the tailstock center 5, the piston rod 24 is retracted. As a result, the draw rod 18 is moved backward by the expansion action of the spring 23, and the gripper 19 expands the extended grip portion 9 in the radial direction and is evenly crimped and clamped onto the inner peripheral surface of the inner hole Wd of the workpiece W. The workpiece W is substantially integrated with the spindle center 4, and the rotation of the spindle 3 is transmitted to the collet body 7 via the spindle center 4, the drive pin 14, and the flange portion 10.

As described above, this invention has the following effects.

The collet body, which must be inserted into the spindle center while allowing radial displacement, has its shaft supported within the center hole of the spindle center by an annular elastic body, so the collet body always remains on the spindle axis. When the workpiece is carried in by the workpiece carrying device, it is installed smoothly and reliably without interfering with the collet.Moreover, the misalignment after installation is absorbed by the radial movement of the collet body due to the elastic deformation of the annular elastic body. Obtained by displacement.

In addition, the coolant seeping from the workpiece support part of the spindle center is prevented from entering the collector body by filling the split groove of the extended grip part with seal rubber, and the annular elastic body is attached to the outer periphery of the collector body by the seal ring. Since this prevents the collector from entering the center of the spindle, it has the advantage of ensuring smooth floating of the collector body over a long period of time.

Furthermore, the above functions and effects are achieved by interposing an annular elastic body between the collet body and the spindle center, so it also has the advantage of solving the conventional problems with a simple structure. .

[Brief explanation of the drawing]

The drawing is a sectional view of this invention. 1... Headstock, 3... Spindle, 4... Spindle center, 7... Collet body, 9... Extended gripping section, 1
4... Drive pin, 16... Annular elastic body, 18...
Dororod, 19... Kotsuta, 24... Piston Rod.

Claims (1)

[Scope of utility model registration request] The collet main body, which has an expanded gripping part at the tip that expands and contracts as the collet moves forward and backward and presses against the inner circumferential surface of the inner hole of the workpiece, is moved in the radial direction to the axial center hole at the tip of the spindle center. The workpiece is characterized in that it is fitted so as to be able to rotate integrally with the center of the spindle by a power transmission mechanism in the rotational direction, and that an annular elastic body is fitted between the outer periphery of the collector body and the center hole of the center of the spindle. Object drive device.