JPH048174B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for grinding a circular body such as a cylinder or a cylindrical body, and more specifically, the present invention relates to a method for grinding a circular body such as a cylinder or a cylindrical body. The present invention relates to a method for grinding a circular object, in which a relief groove is formed and the relief groove is erased during oscillation grinding.

Conventional methods for grinding cylindrical bodies, cylindrical bodies, etc. include traverse grinding, plunge grinding, and oscillation grinding. Among these, oscillation grinding is a method in which either the workpiece or the grinding wheel is reciprocated relative to the longitudinal direction with a relatively short stroke, and the machined surface can be precisely ground with high efficiency. . Therefore, it can be said that this method is particularly suitable for grinding ultra-hard materials with high precision.

For example, if we explain the conventional technology related to automobiles, the following methods have been adopted so far. That is, as the output and rotational speed of the engine have increased, the load on the bearings has also increased. For this reason, it is necessary to improve the finishing accuracy of not only the bearing metal but also the shaft supported by the bearing metal, and to increase the load capacity of the bearing. As a result, after the normal grinding, the machined shaft is subjected to super-finishing using methods such as paper lapping, a combination of paper lapping and polishing with chromium oxide, or polishing with a finishing whetstone, in order to improve the metal contact between the shaft and the bearing. It came.

However, it has been extremely difficult to achieve a highly accurate shape using paper lap or chemical grinding.

In order to avoid these difficulties, oscillation grinding as described above has been adopted for bearings, but this method also has the following problems. That is, when pressing a grindstone against the peripheral surface of a rotating processing shaft to grind the peripheral surface of the processing shaft, sufficient shape accuracy of the processing surface cannot be obtained unless the grindstone performs oscillation grinding in the direction of the processing axis. However, when oscillation is applied to the grindstone, the boundary between the band-shaped processed surface and the non-processed surface becomes unclear, and a sloped portion (sag) that cannot be used effectively is created between the two.

As described above, since superfinishing using a grindstone improves shape accuracy by overtravel or oscillation of the grindstone, the conventional method has the disadvantage that the effective shaft width is reduced. This is a big problem, especially in the case of engine crankshafts that are subjected to very heavy loads.

Therefore, the inventors of the present invention took advantage of the advantage of machining using a grindstone, which allows for highly accurate shapes to be obtained.
Moreover, as a result of extensive research into a method of machining a circular object by oscillation grinding that does not reduce the effective machining width, we created a relief groove approximately equal to the grinding width between the machined surface and the non-machined surface in advance. Furthermore, it has been found that if the depth is set below the machining depth, an ideal shaft finishing method can be obtained that eliminates the sag that is a drawback of the conventional finishing method described above.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a finishing method for a shaft that has high shape accuracy and does not reduce the effective machining width. More specifically, the object of the present invention is to provide a finishing method for a circular body that takes advantage of the high machining accuracy of a grindstone and does not reduce the effective machining width.

In order to achieve the above object, the present invention presses a grindstone against the outer circumferential surface of a rotating circular body, and while making a minute reciprocating motion in a direction perpendicular to the rotational direction of the circular body, the present invention In a grinding method in which the machined surface of a circular body is ground with the grindstone, two annular grooves are carved in advance on the outer circumferential surface of the circular body at a depth substantially equal to the working depth of the grinding process and spaced apart from each other by a predetermined distance. and a step of grinding the remaining machined surface up to the processing depth of the groove, and the two grooves are spaced apart by a width substantially the same as a predetermined grinding width. do.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, with reference to preferred embodiments and apparatus for carrying out the invention.

FIG. 1 shows a plate-shaped grindstone used for grinding grooves, and a holder 10 is composed of an insertion part 12 and a grindstone support part 14. A pair of plate-shaped grindstones 18, 18 are held at both ends of the grindstone mounting surface 16 of the grindstone support portion 14. In this case, these plate-shaped grindstones 18, 18 have a width W that is approximately equal to the effective grinding width, and have a width W that is approximately equal to the effective grinding width, and also has a width W that is approximately the same as the effective grinding width, and also has a width W that is approximately equal to the effective grinding width, and is
A notch 22 having a curvature corresponding to the radius of is provided.

Next, a method of forming grooves in advance on a shaft to be machined using the plate-shaped grindstones 18 will be described.
As shown in FIGS. 2 and 3, the insertion part 12 of this holder 10 is inserted into a recess 26 formed in a grindstone head 24 of a cylindrical grinding machine (not shown), and rotated in the direction of arrow A. Press against the peripheral surface 28 of the processing shaft 20. At this time, it is preferable to apply a minute oscillation in the axial direction B perpendicular to the rotational direction A. In this way, the belt-shaped machining surface 3 of the machining shaft 20
0 and the unprocessed surface 32, that is, the processed surface 30
A pair of annular grooves 34 are formed at both ends of the groove. Note that the depth of the groove 34 is set to a value substantially equal to the machining depth of the machining surface 30.

Next, with reference to FIGS. 4 to 7, a finishing whetstone for oscillation grinding the band-shaped processed surface 30 sandwiched between the grooves 34 will be described. Holder 3
6 includes an insertion part 38 and a grindstone support part 40. The finishing whetstone 42 has this whetstone support part 4 on one side.
It is fixed at 0. The pressing surface of the support portion 40 located on the opposite side of the grindstone fixing surface forms a concave surface 44 with a curvature corresponding to the radius of the processing shaft 20, and the concave surface 44 has a length sufficiently shorter than the interval between the grooves 34, 34. It has a certain quality.

A finishing method for grinding the processing surface 30 of the processing shaft 20 in which the grooves 34 have been formed in advance as described above using the finishing grindstone 42 is as follows.

As shown in FIG. 5, the insertion part 38 of the holder 36 is inserted into the recess 48 of the grindstone head 46 formed corresponding to the insertion part, and is tightened and fixed with bolts and nuts 50. In this way, the pressing concave surface 44 of the grindstone 42 supported by the grindstone head 46 is pressed against the processing surface 30 of the processing shaft 20 rotating in the direction of arrow A. That is, the grindstone 42 is pressed within the interval between the grooves 34, 34, and a relatively large oscillation in the direction of arrow C is applied to the grindstone 42, thereby grinding the machined surface 30 with high shape accuracy. As mentioned above, the depth from the non-machined surface 32 to the groove 34 is set to be substantially equal to the grinding depth of the finishing grindstone 42. Therefore, when the finish machining of the machined surface 30 is completed, the bottom of the groove 34 and the machined surface 30 are flush with each other, and the outer wall of the groove 34 forms a boundary between the machined surface 30 and the non-processed surface 32 (Fig. 7). reference). Although it has been mentioned here that the depth of the groove 34 is substantially equal to the machining depth of the machined surface 30, this means that the groove 34 does not remain between the machined surface 30 and the non-machined surface 32 and is completely erased. , moreover, it means a range in which no sagging due to oscillation occurs between the two. Therefore, even if the machining depth of the machining surface 30 is somewhat greater than the depth of the groove 34, the two are substantially equal as long as the difference is such that no sag occurs.

FIG. 8 is a curve showing the time relationship between the above-mentioned processing steps. Curve D is the grooving time with the plate-shaped grindstone 18, curve E is the grinding finish process with the finishing grindstone 42, that is, the shaft machining time cycle, curve F is the rotation time of the processing shaft 20, and curve G is the plate-shaped The duration of oscillation of the grindstone 18 and the finishing grindstone 42 is shown.

Note that in the method according to the above embodiment, the shaft is ground after the grooving process is completed;
You can do both at the same time. That is, the plate-shaped grindstone 18 and the finishing grindstone 42 are simultaneously pressed against the surface 28 of the rotating processing shaft 20 from the left and right sides (see FIG. 9),
While forming grooves 34 with the plate-shaped grindstone 18, the processing surface 30 is ground while applying oscillation to the finishing grindstone 42 using the grooves 34.

Further, in the method according to the above-described embodiment, the machining depth of the machining surface 30 is kept constant, but it is also possible to increase the depth as the depth approaches the boundary of the machining surface 30. That is, the pressing concave surface 44 of the finishing whetstone 42 is also curved in the axial direction of the processing shaft 20 so as to be concave with respect to the circumferential surface 28 of the processing shaft 20, and this is pressed against the processing surface 30 (10th
(see figure). In this case, it is easily understood that the depth of the groove 34 is substantially the same as the machining depth of the boundary portion of the machining surface 30.

In the present invention, as described above, a groove with a depth substantially equal to the machining depth of the machining surface of the machining axis is formed in advance at the end of the machining surface, and the machining surface is ground while giving oscillation to the finishing whetstone, so that effective machining can be achieved. Finishing can be performed with high shape accuracy without reducing the width.

The present invention has been described above with reference to preferred embodiments, but the present invention is not limited to these embodiments, and can be applied to cylindrical bodies other than shafts, as well as grinding of cylindrical bodies. Of course, various improvements and design changes are possible without departing from the above.

[Brief explanation of drawings]

Figure 1 is a perspective view of a plate-shaped grindstone that performs grooving on a processing shaft according to the method of the present invention, and Figure 2 shows that the grindstone shown in Figure 1 is pressed against the processing shaft to perform grooving. FIG. 3 is a partially cutaway plan view of the machining state shown in FIG. Fig. 5 is a front view showing the state in which the grindstone shown in Fig. 4 is pressed against the processing shaft for grinding, and Fig. 6 is a front view showing the state in which the grindstone shown in Fig. 5 is pressed against the processing shaft for grinding. A plan view showing the state in which finishing processing is being performed,
FIG. 7 is a plan view showing the relationship between the grinding wheel and the shaft when grinding has almost reached the completion stage, FIG. 8 is a curve showing the time relationship of each processing step according to the method of the present invention, and FIG.
Figure 10 is a plan view showing another embodiment of the present invention.
The figure is a partially omitted sectional view showing still another embodiment of the present invention. 10... Holder, 12... Insertion part, 14... Grindstone support part, 16... Grindstone mounting surface, 18... Plate grindstone, 20... Machining shaft, 22... Notch, 24... Grindstone head, 26... Recess, 28... Circumferential surface, 30... Processed surface, 32... Unprocessed surface, 34... Groove, 36...
holder, 38...insertion part, 40...grindstone support part,
42... Finishing whetstone, 44... Pressing concave surface, 46...
Grindstone head, 48... recess.

Claims (1)

[Scope of Claims] 1. A grindstone is pressed against the outer circumferential surface of a rotating circular body, and the machined surface of the circular body is machined while the grindstone is made a minute reciprocating motion in a direction perpendicular to the rotational direction of the circular body. The grinding method includes the steps of: carving in advance two annular grooves on the outer circumferential surface of the circular body at a depth substantially equal to the processing depth of the grinding process and spaced apart from each other by a predetermined distance; Grinding the remaining machined surface up to the processing depth, the two grooves being spaced apart by substantially the same width as a predetermined grinding width. Method. 2. In the method described in claim 1,
When performing rotational movement around the axis of the circular body,
Pressing a set of plate-shaped grindstones on the outer peripheral surface of the circular body,
A method for grinding a circular body, comprising grinding the circumferential surface of the circular body to form two grooves spaced apart by a predetermined distance. 3. In the method described in claim 2,
A method for grinding a circular body, comprising a notch having a radius of curvature corresponding to the radius of the circular body on the end face of a plate-shaped grindstone.