JPH0369665B2 - - Google Patents

Description

Detailed Description of the Invention The present invention has a tightening flange and a support flange, and a plurality of wedges extending in the longitudinal direction and protruding in the radial direction are provided on the circumferential surface of the support portion of the support flange. This invention relates to a tightening device for a ring-shaped grindstone, in which a groove is provided in a hole of the ring-shaped grindstone to correspond to a wedge.

Ring-shaped grinding wheels usually have a circular hole, and correspondingly the support pins of the clamping flange are also usually circular in cross-section. Since the grinding wheel rotates at a very high speed, if the grinding wheel bearing is eccentric, a dangerously large inertial force will be generated. Therefore, when fixing the grinding wheel, care must be taken to carefully prevent imbalance and to ensure accurate centering. In the known ring-shaped grinding wheels, therefore, the gap between the hole in the grinding wheel and the support pin is kept very small. Although this prevents unbalance, it has the disadvantage that it becomes very difficult to fit the grinding wheel onto the support pin. In other words, since the gap is extremely small, the whetstone tends to tilt when it is fitted, requiring a lot of skill each time, and even if the tilt can be corrected, there is a risk of breaking the whetstone by trying again to fit it into the support pin. It is impossible without it. Many industrial accidents during grinding are due to virtually invisible defects sustained by the grinding wheel when it is secured to a clamping device.

Conventionally, when using a grinding wheel in a grinding machine, the grinding wheel is fitted into a support part of a spindle or a support flange, and the grinding wheel is fixed at an end position, for example, by a tightening flange (as disclosed in US Pat. 2497217). A major drawback of this known grinding wheel clamping device is that, due to the small tolerances, it is difficult to fit the grinding wheel into the support, especially if the grinding wheel is fitted into the support with a slight inclination. Not only will it be impossible to do so, but the hole in the whetstone may even be damaged when it is tilted. This also results in the disadvantage that the grindstone rotates eccentrically.

Furthermore, a ring-shaped grindstone tightening device (French Patent Specification No.
445807) is also well known, but this also has the drawbacks mentioned above.

Furthermore, although it is not a grindstone tightening device, it is
As stated in Publication No. 68707 and its full specification,
The annular circumferential surface of the stator fixed to the tube end of the inner round tube is formed into an eccentric circular surface with equal diameter of one-third of the circumference, and an eccentric circular surface with the same shape as the above-mentioned equal diameter eccentric circular surface is formed on the inner circumference. The C-shaped band ring formed on the surface is fitted into the annular groove of the stator, and by rotating the stator, the diameter of the C-shaped band ring is expanded outward, and as a result, the inner peripheral surface of the outer round tube A fixing device is also known in which both round tubes are attached by pressing them against each other. However, this configuration requires a C-shaped band ring as a completely separate member in addition to the two elements that are to be engaged, and furthermore, this C-shaped band ring itself has an outer peripheral shape of the stator. It must have a predetermined shape and dimensions. Since there is almost no gap between the outer circumferential surface of the stator, which has eccentric circular surfaces of the same shape on the inner or outer surface, and the inner circumferential surface of the C-shaped band ring, it is difficult to align and assemble the two. This method has the same drawback as the prior art described above in that it is extremely difficult to do so. Furthermore, the need to prepare a C-shaped band ring with an eccentric circular surface of the same shape is itself a cause of high costs, and engagement is achieved by expanding the C-shaped band ring. C
Since the fulcrum of the expanding movement of the mold band ring is deviated from the central position, highly accurate centering cannot be expected at all.

It is an object of the present invention to enable ring-shaped grinding wheels to be produced more cheaply than ever before, with larger radial tolerances, i.e., hole gaps, and thus to facilitate fitting into support flanges. The object of the present invention is to improve the conventional ring-shaped grinding wheel device in such a way that sufficient centering and perfect concentric rotation can be easily obtained by reducing the gap before fixing.

According to the first aspect of the present invention, this purpose is to reduce the radius of the support portion of the drive shaft including the wedge (however, in the first aspect, it is a protrusion that does not have a substantial wedge effect). This is achieved by making the radius very slightly smaller than the radius of the hole in the shape grindstone.

Preferably, three wedges are provided at equal intervals on the circumferential surface of the support portion of the support flange.

Preferably, the tolerance between the two radii is at most 5 μm.

The tightening device according to the present invention is particularly for a ring-shaped grinding wheel composed of cubic boron nitride, and when the radial tolerance of the hole in the grinding wheel is around 5 μm with respect to the diameter of the support part, the tightening device is suitable for ring-shaped grinding wheels made of cubic boron nitride. In contrast to the method in which the grindstone cannot be attached, the present invention allows the grindstone to be easily fitted into the support as long as the grooves of the grindstone are aligned in a straight line facing the wedges on the circumferential surface of the support. has great advantages. The required fit can be obtained by simply standing the grindstone perpendicular to the axis of the support and then turning the grindstone. In this state, the grindstone is fixed between the support flange and the clamping flange as usual.

In order to achieve the above object, in a second aspect of the present invention, the cross-sectional profile of each wedge having a substantially wedge action is varied from a small radius smaller than the radius of the hole of the ring-shaped grinding wheel to a radius larger than the radius of the hole. It can be formed to gradually rise to a larger radius.

Even when the outer contour of the cross-sectional profile rises, such as a wedge-shaped sliding surface, the wedge comes into contact with the groove edge of the grinding wheel, and the grinding wheel is controlled by the wedge-shaped slope and slides to the exactly centered position. Then centering is performed. This centering method eliminates the need for a narrow concentric seat of the wedge in the wheel hole, and thus eliminates the need to use wheels with tight radial tolerances. Grinding wheels with relatively wide radial tolerances can be manufactured relatively inexpensively.

Preferably, the ascending cross-sectional profile of each wedge from the minor radius to the major radius is an arc of radius having a center of curvature laterally offset from the center of the support portion of the support flange by a certain eccentricity. This allows for some flexibility in centering due to the increased radial tolerances of the ring-shaped grinding wheel, and furthermore, the rising wedge profile of the cross-section can be easily processed on a conventional milling machine without the need for complex special equipment. It also has the advantage of being able to be manufactured with

Advantageously, the profile of each wedge rises in a direction opposite to the direction of rotation of the support.

In a tightening device configured in this way, torque is also transmitted from the support flange to the grinding wheel fixed thereto by means of a frictional connection. Therefore, no rotational force is transmitted to the portion where the wedge is not yet centered and rests against the groove edge, and the grinding wheel can rotate in both directions. It is not normal for the grinding wheel to loosen its grip on the support flange, but if for some reason it does, the wedge will move away from the groove edge, canceling out the centering, and immediately creating a large imbalance that can cause serious damage or damage. It may even cause an accident. The tightening device according to the invention prevents this. This is because centering is maintained even in such emergencies, so that dangerous imbalances are avoided.

In both the first and second aspects of the present invention, it is preferable to arrange three wedges at equal intervals on the circumferential surface of the support portion of the support flange. Just as a three-legged chair does not wobble, a support with three equally spaced wedges can also rest on the grindstone at three equally spaced locations (and only at three locations).

The tightening device configured in this manner not only allows ring-shaped grindstones to be easily fitted and accurately centered, but also has a great advantage in that grindstones with large radial tolerances can be manufactured at low cost.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Other advantages of the invention will become apparent from the description below.

In the first aspect of the invention shown in FIG. 1, a ring-shaped grindstone 1 is fitted through its hole 10 into a support 3 of a tightening device attached to a drive shaft 4.
The support part 3 is part of a support flange 5, which has a flat annular surface as a clamping surface 6, which clamping surface 6 is exactly perpendicular to the longitudinal axis of the drive shaft 4.

As shown in FIG. 1, the grinding wheel 1 has a support flange 5
It is held on the support part 3 by a tightening flange 2 which is screwed on.

The hole 10 having an inner radius B1 has three grooves 8 parallel to the axis at equal intervals, as clearly shown in FIGS. 2-4, while wedges 9 are also provided at equal intervals on the circumference of the support 3. There is. Wedge 9 is the width of groove 8 of grindstone 1
slightly narrower than The outer surface of the wedge 9 is a cylindrical surface and lies on a radius D1 that is very slightly smaller than the radius B1. Therefore, by forming a groove 8 wider than this at a position facing the wedge 9, the grindstone 1 can be fitted into the support part 3 with a gap so large that it does not touch the support part 3 at all. I can do it. If the front surface 7 of the grinding wheel 1 is brought into contact with the support flange 5, the grinding wheel will be exactly perpendicular to the axis of rotation. Thereafter, the grindstone 1 is rotated together with its support 3 relative to the flange 5 until it reaches the state shown in FIG. Finally, the grinding wheel 1 is secured to a clamping device in a known manner, for example using the clamping flange 2 shown in FIG.

As a result, the grindstone 1 rotates in a perfect circle, so it will not be damaged and can be assembled very easily. Furthermore, the radius D1 of the wedge 9
(see FIG. 2) is approximately equal to the radius B1 of the hole 10 of the grindstone, and the centering of the grindstone at the support portion can be performed in μm units.

The tightening device according to the second aspect of the present invention shown in FIGS. 5 and 6 is also for fixing the ring-shaped grindstone 1. Experience has shown that this abrasive wheel formed from boron nitride with a suitable bonding agent is extremely sensitive to unbalance. The clamping device consists of a drive shaft 2, a support flange 5, a support pin 3, a clamping surface 6 and a clamping flange 2.

The grindstone 1 is installed as follows. Fit the grindstone into the support part 3 of the support flange 5 until the grindstone 1 contacts the clamping surface 6, then fit the clamping flange 2 onto the support pin 3 of the support flange 5 until the clamping flange 2 contacts the grindstone 1. Finally, the grindstone 1 is centered, and the clamping flange 2 is fastened to the support flange 5 using screws (indicated by dashed lines in FIG. 1). As a result, the grindstone 1 is fixed, and when the drive shaft 4 rotates, the grindstone 1 also rotates due to the frictional coupling between the flanges 2 and 5.

As shown in Figures 5 and 6, the grinding wheel 1 is placed in the hole 10.
It has a plurality of grooves 8 which are also axis-parallel and which are equidistantly spaced, that is to say offset from each other by 120°. The support part 3 of the support flange 5 again has three equally spaced wedges 11, 12, 13 offset by 120 DEG. Each wedge 11, 12, 13 (wedge 11 in Figures 5 and 6)
The cross-sectional profile of (see) gradually rises from a small radius R1 smaller than the hole radius B1 to a larger radius R2 larger than the hole radius B1. As a result, the outline of the wedge 11 is a slope acting as a wedge, and when the grinding wheel 1 is turned clockwise, the slope moves along the edge of the groove 8. This is the same for all three wedges 11, 12, 13. Therefore, when the grinding wheel 1 is turned clockwise, it abuts the contours of all three wedges and slides under the control of these contours to the centering position shown in FIG. At this position, the tightening flange 2 is tightened to fix the grindstone.

In other words, in the second aspect of the present invention shown in FIGS. 5 and 6, it is possible to easily fit the grinding wheel with a large play as shown in FIG. Accurate centering can be performed without having a narrow seat at the center of the hole 10. Or rather, wedges 11, 12, 1
A wedge effect is formed between the rising contour of 3 and the edge of the groove 8, resulting in the narrow "seat" required for centering. It is thus possible to use a grinding wheel 1 with relatively large radial tolerances in the hole 10 of the grinding wheel. Such wheels can be manufactured more cheaply than conventional ring-shaped wheels because the radial tolerances of the holes may be large.

The direction of rotation of the tightening device is indicated by arrow 15 in FIG. Preferably, the profile of the wedge rises in the opposite direction to the direction of rotation of the arrow 15, for example from the small radius R1 of the wedge 11 to the large radius R2.

The rise of the wedge profile from the small radius R1 to the large radius R2 can be realized in various ways. In principle, a linear rise is also possible, but FIG. 6 shows a very simple solution in terms of manufacturing technology. According to this, the outline of the wedge 11 is a circular arc, and the center of curvature M2 of the circular arc having a radius R is laterally shifted from the center M1 of the support portion 3 of the support flange 5 by an eccentricity X.

[Brief explanation of drawings]

FIG. 1 is a partially sectional side view showing a ring-shaped grindstone, a tightening device, and an assembled state. FIG. 2 is an enlarged view of the "X" portion in FIG. 3 showing the tightening device according to the first aspect of the present invention. FIG. 3 is a sectional view showing the relative position of the grindstone with respect to the support portion of the support flange during assembly of the grindstone in the tightening device according to the first aspect of the present invention. FIG. 4 is a sectional view corresponding to FIG. 3 showing the state after the grindstone has been rotated with respect to the support portion. FIG. 5 is a sectional view of the tightening device according to the second aspect of the present invention taken along the line A--A in FIG. 1 at the centering position. FIG. 6 is an enlarged view of a portion of FIG. 5 in the fitted position. 1...Ring-shaped grindstone, 2...Tightening flange, 3
... Support part, 5 ... Support flange, 8 ... Groove,
9, 11, 12, 13... Wedge, 10... Hole of ring-shaped grindstone, B1... Radius of hole of ring-shaped grindstone, D1, R1, R2... Radius of wedge.

Claims (1)

[Scope of Claims] 1. A clamping flange and a support flange, and a plurality of wedge-shaped protrusions extending in the longitudinal direction and protruding in the radial direction are provided on the peripheral surface of the support portion of the support flange, and the wedge-shaped A groove wider than the wedge-shaped projection is provided in the hole of the ring-shaped grinding wheel corresponding to the projection, and the radius D1 including the wedge-shaped projection 9 is larger than the radius B1 of the hole of the ring-shaped grinding wheel 1 not including the groove. A ring-shaped grindstone tightening device that is extremely small. 2. The tightening device according to claim 1, characterized in that three wedge-shaped protrusions 9 are provided at equal intervals on the circumferential surface of the support portion 3 of the support flange 5. 3. The tightening device according to claim 1 or 2, wherein the difference between the two radii D1 and B2 is at most 5 μm. 4. It has a tightening flange and a support flange, and a plurality of wedges extending in the longitudinal direction and protruding in the radial direction are provided on the peripheral surface of the support part of the support flange, and holes in the ring-shaped grindstone are formed in correspondence with the wedges. A groove wider than the above wedge is provided in each of the wedges 11, 12, 1.
3, the cross-sectional profile of the ring-shaped grinding wheel 1 gradually rises from a small radius R1 smaller than the radius B1 of the hole not including the groove to a larger radius R2 larger than the radius B1 of the hole. Grinding wheel tightening device. 5 The cross-sectional contour of each wedge 11, 12, 13 rising from the small radius R1 to the second radius R2 is shifted laterally by a certain eccentricity x from the center M1 of the support portion 3 of the support flange 5. The tightening device according to claim 4, wherein the tightening device is a circular arc having a radius R and a center of curvature M2. 6. A tightening device according to claim 4, characterized in that the cross-sectional contour of each wedge (11, 12, 13) rises in a direction opposite to the direction of rotation (15) of the support (3). 7. The tightening device according to claim 4, characterized in that three wedges 11, 12, 13 are arranged at equal intervals on the circumferential surface of the support portion 3 of the support flange 5.