JPS61279404A - Chucking device for cylindrical work - Google Patents

Abstract

PURPOSE:To prevent a work from being deformed and accurately machine the work as desired, by inserting a split collect into a cylinder of the cylindrical work while a tapered spindle into the collect by a suitable pressure and permitting a main spindle to hole the work. CONSTITUTION:A main spindle 30 provides in its point end integrally and concentrically a split collect 32 having a slit 34. A chucking device, inserting the collect 32 into the cylinder of a work W, adapts a large contour part 36 to an inner side of the cylindrical work. The device spreads the collet 32 to the outer by forcing a tapered spindle 40, mounted to a tailstock or the like, to be fitted to a tapered hole 38 of the collet 32. The device, spreading also the large contour part 36 to the outer, holds the work W to be fixed to the collet 32. Subsequently, the work is machined for its peripheral surface or both end surfaces.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to an improvement in a chucking device for holding a cylindrical workpiece on the main shaft of a machine tool based on its inner diameter (compared to the prior art). Problems) When grinding the outer circumferential surface of a hollow cylindrical workpiece, conventionally the cylindrical workpiece W is generally chucked into a cylindrical grinder or the like as shown in FIG.

In FIG. 3, 10 is a mandrel, 12 is a tailstock shaft, and the small diameter portions 10a and 12a at the tips of these are connected to the cylindrical workpiece W.
is inserted into the cylinder from both ends of the cylindrical workpiece W, and both end surfaces of the cylindrical workpiece W are sandwiched and fixed from both sides by the stepped portions at the roots of the small diameter portions ioa and i2a.

The chucking device shown in FIG. 3 has a problem in that both end surfaces of the cylindrical workpiece W cannot be processed because both end surfaces of the cylindrical workpiece W are held down by the stepped portions of the mandrel 10 and the tailstock shaft 12. Furthermore, when chucking the workpiece W based on the inner diameter of the tube, the small diameter part 10a of the mandrel 10 and the small diameter part 12a of the tail stock @12 must be made to almost match the inner diameter of the cylindrical workpiece W. The fitting between the mandrel 10 and the tailstock shaft 12 becomes too tight, and the mandrel 10 and the tailstock shaft 12 cannot be inserted into the workpiece W depending on an error in the inner diameter of the workpiece W.

Therefore, in reality, the small diameter portion 10a. A slight difference must be made between the inner diameter of the work W and the inner diameter of the work W, and this becomes an error of the work W. If the workpiece W is not correctly positioned based on the inner diameter and the outer peripheral surface is subjected to grinding, the cylindricity of the outer diameter and the coaxiality between the inner diameter and the outer diameter deteriorate.

FIG. 4 shows another conventional example. Here, an annular rubber pad 14 is fitted to the small diameter portion 10a of the mandrel 10, and a metal bushing 16 is fitted to the tip side of the rubber pad 14, and the end surface of the bushing 16 is connected to a bolt 18 screwed into the tip of the mandrel 10 and a washer 20. It is configured to press in the axial direction. The outer diameter of the rubber pad 14 is slightly smaller than the inner diameter of the cylindrical work W.

Insert this device into the cylinder of the cylindrical workpiece W, and
4 is near the center of the workpiece W, and bolt 1
8 is screwed in, the rubber pad 14 is compressed in the axial direction, and the outer diameter of the rubber pad 14 is expanded by compressive deformation. Due to the expansion of the outer diameter of the rubber pad 14, force acts radially on the inner peripheral surface of the cylindrical work W, and the work W is fixed by this force.

The chucking device shown in Fig. 4 enables machining of the end face of the workpiece W, but the workpiece W must be fixed and released by rotating the bolt 18, and it takes time to attach and detach the workpiece W, resulting in poor productivity. There is a problem. In addition, the rubber pad 14 was severely worn and had to be replaced frequently, which was also very troublesome.

(Objective of the Invention) This invention was made in view of the above-mentioned conventional problems, and its purpose is to enable end face processing of a cylindrical workpiece, to accurately position the cylindrical workpiece based on the inner diameter of the cylindrical workpiece, and to To provide a chucking device which can be attached and detached very easily and in a short time.

(Structure of the Invention) Therefore, in the present invention, a split collet having an outer diameter slightly smaller than the inner diameter of the work is inserted into the cylinder of a cylindrical work, and a tapered shaft is inserted into the cylinder from the end face of the split collet to apply appropriate pressure. By inserting the split collet, the outer diameter of the split collet is expanded, and the cylindrical workpiece is held by a force that acts radially on the inner circumferential surface of the split collet.

(Embodiment) FIGS. 1 and 2 show a chucking device according to an embodiment of the present invention. In both figures, 30 is a main shaft, and a splitting collet 32 is integrally and concentrically attached to the tip of this main shaft 30.
is provided. The split collet 32 is a cylindrical body having a tapered hole 38 with a large diameter toward the open end, and a plurality of slits 34 are formed at equal intervals along the axial direction from the tip side.

Further, a large diameter portion 36 in the form of an annular band is integrally formed in the center portion of the split collet 32. The outer diameter of this large diameter portion 36 is slightly smaller than the inner diameter of the cylindrical workpiece W.

A tapered shaft 40 is attached to a tailstock or the like coaxially with the main shaft 30 and facing the split collet 32. The tip side facing the split collet 32 is tapered, and the tapered hole 38 of the split collet 32 is tapered. Fits concentrically.

The tapered shaft 40 is reciprocated in the axial direction by a feed mechanism (not shown), but the pressing force when fitting the tapered shaft 40 into the taper hole 38 of the split collet 32 is adjusted to a predetermined amount by a spring or the like. is controlled by.

In order to chuck the cylindrical workpiece W using the above-mentioned chucking device, first, the tapered shaft 40 is moved backward,
This is pulled out from the tapered hole 38 of the split collet 32. Next, the workpiece W is mounted so that the split collet 32 is relatively inserted into the cylinder of the cylindrical workpiece W, and the workpiece W is brought into a position where the belt-shaped large diameter portion 36 is applied to the central portion of the workpiece W.

Next, the tapered shaft 40 is advanced, and the tapered tip portion is press-fitted into the tapered hole 38 of the split collet 32. The pressing force of the tapered shaft 40 at this time is controlled by a spring or the like as described above.

By press-fitting the tapered shaft 40, the slit 34
The split collet 32 having a split collet 32 expands outward due to the calibration effect, and its outer diameter expands. Of course, the outer diameter of the large diameter portion 36' is expanded, and its circumferential surface uniformly contacts the inner circumferential surface of the cylindrical workpiece W, and a uniform pressing force acts radially on the inner circumferential surface of the cylindrical workpiece W. This pressing force splits the cylindrical workpiece into collet 3.
It is held fixed at 2.

FIG. 1 shows a state in which the cylindrical work W is fixed to the split collet 32, and as is clear from the figure, the cylindrical work W
Not only the outer circumferential surface of the workpiece W but also both end surfaces of the workpiece W can be processed without any problem.

To remove the workpiece, split the taper shaft 40 with the collet 3.
2, and then the fixing force of the cylindrical workpiece W will no longer act, so the workpiece W can be easily removed from the split collet 32. The above-described operation of attaching and detaching the work W can be easily automated using a simple handling device and can be performed at extremely high speed.

As is clear from the above explanation, the force for fixing the workpiece W can be adjusted by the pressing force of the tapered shaft 40 against the split collet 32, and this pressing force can be set appropriately according to the strength and dimensions of the workpiece W. put. In this way, the fixed state of the workpiece W is extremely stable, and deformation of the workpiece W can be prevented, and high machining accuracy can be obtained due to the accurate inner diameter reference.

(Effects of the Invention) As explained in detail above, according to the chucking device for a cylindrical workpiece according to the present invention, it is possible to grind not only the outer peripheral surface but also both end surfaces of the cylindrical workpiece while it is being chucked. Moreover, the operation of attaching and detaching the workpiece W is extremely simple, and automation and speeding up are easy. In addition, since the cylindrical workpiece can be accurately positioned with respect to the inner diameter, it is possible to perform processing to achieve high precision in the cylindricity of the outer diameter and the coaxiality of the inner and outer diameters.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a cylindrical workpiece fixed to a chucking device according to an embodiment of the present invention, FIG. 2 is a perspective view showing details of the split collet 32 in FIG. 1, and FIGS. 3 and 4. 1A and 1B are cross-sectional views showing two configuration examples of a conventional chucking device for a cylindrical workpiece. W...Work 32...Split collet 34...Slit 36...Large diameter part 38...
・Tapered hole 40...Tapered shaft Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] (1) By inserting a split collet with an outer diameter slightly smaller than the inner diameter of the workpiece into the cylinder of a cylindrical workpiece, and inserting a tapered shaft into the cylinder from the end face of the splitting collet with appropriate pressure, the above-mentioned A chucking device for a cylindrical workpiece, characterized in that the outer diameter of a split collet is expanded and the cylindrical workpiece is held by a force that acts radially on the inner peripheral surface of the cylindrical workpiece.