JPS5935745B2 - Super-finishing device for annular workpieces on a super-finishing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a super-finishing device for annular workpieces such as inner and outer races of ball bearings in a super-finishing machine.

In general, workpieces to be superfinished are ones that have been subjected to precision finishing such as grinding and precision turning prior to processing. Their finished surface is quite smooth, but the finished surface has a maximum height of 2~
It consists of peaks and valleys with an unevenness of about 10μ. When this is superfinished using an oil whetstone, even though the pressure applied to the whetstone is small at the beginning, the area of the uneven ridges that maintain contact with the whetstone is very small, so A large pressure is applied per unit area, and the peaks are rapidly removed. Then, as the workpiece is gradually removed, the roughness of the finished surface becomes smooth, corresponding to the roughness of the scratches produced by the grindstone. Since the contact area between the workpiece and the grindstone increases step by step as the work progresses, the pressure per unit area decreases and the finishing efficiency gradually decreases. Furthermore, the generated metal chips become stuck in the gaps between the abrasive grain cutting edges of the grinding wheel, causing clogging. This phenomenon of eye clogging also plays a major role in reducing the grinding efficiency of the grindstone. As superfinishing progresses as described above, the degree of clogging becomes more severe, and eventually the surface of the whetstone becomes completely clogged and appears black. This is the time when super finishing is completed, and the finished surface of the workpiece becomes smooth. The whetstone is <
When clogging occurs, the sharp cutting edges of the abrasive grains are covered with chips, so the grinding action is stopped and the surface of the workpiece is simply rubbed. At this time, the working fluid acts as a lubricant, preventing the cutting edges of the abrasive grains from biting into the workpiece, and also preventing the surface of the workpiece from being rubbed by the clogged grindstone. help. As a result, a thin layer of processing damage forms on the finished surface, making the surface extremely smooth and shiny and mirror-like. In addition, after one workpiece is super-finished in this way, the next workpiece is super-finished, but at this time, the grinding wheel that caused the clogging in the previous process is removed. This means that the grinding ability has been lost.

However, in this case, the irregularities on the surface of the new workpiece will cause strong pressure to be applied to the surface of the grindstone, and the grindstone that has become clogged will need to be reconditioned. Therefore, in superfinishing, the surface of a new workpiece is first reconditioned with a whetstone to ensure that the whetstone is in a sharp condition before work begins; in other words, an automatic reshaping action is performed. Therefore, there is no need to perform additional reshaping work as in the case of grinding. In order to obtain a true mirror surface through super-finishing, the grindstone must become clogged.
It is essential to raise the issue.

However, if clogging occurs, the grinding action stops and only friction is produced on the machined surface. Therefore, it is best to make sure that the amount of workpiece that can be finished before ``clogging'' occurs is equal to the finishing allowance for super-finishing. If ``moon clogging'' occurs before the depth of the flaws from the previous process is reached, the resulting surface will be a mirror surface with the flaws from the previous process remaining in some places, and these flaws will have to be removed. However, the whetstone is clogged and has no grinding ability, requiring a very long time. On the contrary, the radius of the machined surface may become distorted or the cylindricity may deteriorate, resulting in poor accuracy. Therefore, it is necessary to prevent clogging until the necessary finishing allowance, that is, the depth of the flaw in the previous machining, is reached, and to process the work in a short time. This invention uses a super-finishing machine to provide appropriate amplitude motion to the grinding wheel as needed during oscillating super-finishing of the raceway surfaces of the inner and outer races of ball bearings, thereby increasing cutting efficiency and achieving high efficiency and precision. The aim is to apply super-finishing to the material.

The present invention comprises a drive unit that rotates an annular workpiece around the main axis using a shoe center ↓less method, a grindstone holder unit that holds a grindstone pressed against the processing surface of the workpiece, and a grindstone holder unit that is attached to one end of the drive unit. A rocking shaft that is fixed and swings around a rocking axis passing through the center of curvature of the machined surface of the workpiece and perpendicular to the main axis, and a rocking shaft to which the grinding wheel holder unit is fixed are rocked. It is characterized by comprising an amplitude unit that vibrates in the direction of the dynamic axis.

To explain the case where an example of the present invention is applied to an inner groove superfinishing machine for an outer ring of a ball bearing, reference numeral 1 denotes a drive unit in which a backing plate 2 is attached to the tip of a spindle that rotates around the spindle center; As the workpiece rotates, the workpiece W supported by the shutter 3 attached to the work head is rotated while being pressed by the pressure roller 14.

Reference numeral 5 denotes a swing shaft that transmits swing motion to the grindstone C via the grindstone holder unit 6, and this swing shaft 5 is connected to the crank mechanism T,
The swing shaft 5 swings with the rotation of the prime mover 10 via the connecting rod 8 and the swing arm 9, and the swing shaft 5 is centered around the center of curvature o of the ball bearing groove D, which is the machined surface of the workpiece W. It swings around a swing axis 21 that is perpendicular to the main axis and perpendicular to the main axis.

By changing the amount of eccentricity of the eccentric pin 11 of the crank mechanism T, this swinging momentum arbitrarily selects the swinging angle R of the grindstone G and superfinishes the ball bearing groove D into a predetermined arc shape. Reference numeral 12 denotes an amplitude unit that gives an amplitude motion to the grindstone G via the grindstone holder unit 6. This amplitude unit 12 is slidable in the direction of the swing axis 21 with respect to the hydrostatic bearing IT, and
It is vibrated together with the swing shaft 5 in the direction of the swing axis via the vibration arm 14 as the prime mover 15 rotates.

In this case as well, by adjusting the eccentricity between the eccentric shaft 13 and the eccentric sleeve 16, the amplitude P of the grindstone G can be arbitrarily selected. In this case, the holding means of the amplitude unit 12 can be improved in wear resistance by using a static pressure bearing or a plain metal IT, and the center of curvature o of the workpiece W and the center of the swing axis can be Adopts a cored mechanism system that always matches and never goes out of order. Note that since the swing shaft 5 is also vibrated together by the amplitude unit 12, the motor 10 can be fixed by using a self-aligning bearing in the connecting portion 22 between the swing arm 9 and the connecting rod 8. To enable a swing shaft 5 to slightly vibrate while swinging even when the swing shaft 5 is moving. As is well known, the grindstone G of the present invention is fitted into a fixed holder 18 fixed to a grindstone holder unit 6, and has its upper end pressed by a pressure lever 19 fixed to a piston that is constantly pressed inside this unit 6. The grinding wheel G is given an oscillating motion to super-finish the arcuate surface of the ball bearing groove D, and during this oscillating super-finishing process, the grinding wheel G is subjected to oscillating motion to press the lower end to the ball bearing groove D. It is capable of superfinishing the circumferential surface of the ball bearing groove D by repeatedly applying the required amplitude movement in a direction perpendicular to the swinging movement for a certain period of time, or stopping it at a certain position. The cutting effect of the annular workpiece, that is, the ball bearing groove surface D of the inner and outer rings of the ball bearing can be enhanced by the movement, and the finished surface can be efficiently superfinished.

That is, in the present invention, by vibrating the grindstone G in the direction of the rocking axis, the abrasive grains of the grindstone are caused to fall off, and a new cutting edge is generated.

This point will be explained with reference to FIG.

The grindstone G vibrates with an amplitude P in the direction 23 of the oscillation axis on the processing surface D of the rotating workpiece W. The grindstone G moves to the displacement position G1 due to the vibration, but the workpiece W
is rotating, whereas the grindstone is in linear motion,
The pressing force on the left half 25 of the abutment surface 24 of the grindstone G in the figure increases, and this causes the abrasive grains of the grindstone to fall off, forming a new cutting edge. By doing this, it is possible to delay clogging of the grindstone and obtain the necessary finishing allowance. Additionally, in general, the longer you use super finishing, the less accurate it becomes. For example, the shape of the radius may be distorted,
The cylindricity may be lost. Therefore, it is important to cut quickly in order to improve accuracy, but in the present invention, by vibrating the grindstone in the direction of the oscillating axis, the abrasive grains are caused to fall off, making it difficult to reshape. By delaying clogging, the required finishing allowance can be obtained in a short time, allowing for highly accurate super finishing. As described above, the present invention improves the cutting efficiency when superfinishing annular workpieces such as ball bearing grooves, and enables superfinishing with high efficiency and high accuracy.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the application to the inner super finishing machine of the outer ring of a ball bearing, Fig. 2 is a vertical cross-sectional side view of the same, Fig. 3 is a front view showing only the support state of the workpiece, and Fig. 4 is FIG. 5 is a longitudinal sectional front view showing the operating state of the grindstone; FIG. 5 is a longitudinal sectional front view showing the oscillating motion state; FIG.
The figure is a side view showing the contact portion between the grindstone and the workpiece. 1...Drive unit, 3...Shuttle 1, 4...Bresher roller 1, 5......
Swing shaft, 6... Grinding wheel holder, T... Crank mechanism, 10, 15... Prime mover, 11...
... Eccentric pin, 12 ... Amplitude unit, 1
3...Eccentric shaft, 14...Amplitude arm, 16
...Eccentric sleeve, W...Workpiece,
G... Grindstone, R... Rocking angle, D...
...Ball bearing groove (machined surface), P...Amount of amplitude.

Claims (1)

[Claims] 1. A drive unit that rotates an annular workpiece around the main axis using a shoe centerless method, a grindstone holder unit that holds a grindstone pressed against the processing surface of the workpiece, and a grindstone holder unit fixed to one end. The oscillating shaft passes through the center of curvature of the machined surface of the workpiece and oscillates about the oscillating axis that is perpendicular to the main axis, and the oscillating shaft to which the grinding wheel holder unit is fixed is connected to the oscillating shaft. A super-finishing device for an annular workpiece in a super-finishing machine, characterized by comprising an amplitude unit that vibrates in the direction of the center.