JPS61178168A - Machining of clearance groove for superfinishing - Google Patents

Abstract

PURPOSE:To form clearance grooves at both ends of a shank of a work adjacent to the filler radius portions thereof without doing damage to the filler radius portions by employing a belt of abrasive cloth which is pressed by retainer pieces so as to form the clearance grooves. CONSTITUTION:In order to cut clearance grooves, both arms 2 are closed, and an abrasive cloth 7 is pressed into contact with both ends of a shank Wa of a work W by retainer pieces 6 with pressure applied from the backsides of the retainer pieces 6, and then the work W is rotated. Thus, both ends of the shank Wa are ground by the abrasive cloth 7. projections 6a which serve as abutments of the retainer piece 6 against the abrasive cloth 7 can be so thin as to have a width of about 2-3mm and form clearance grooves adjacent to filler radius portions Wb without overlapping them. Even if the side edge of the abrasive cloth 7 rides the filler radius portion Wb, pressing force is not applied so strong at this portion, that the hardened layer Wc produced by cyanide bathing or the like will not be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming relief grooves at both ends of a shaft portion of a workpiece in a pre-process of superfinishing the peripheral surface of the shaft portion.

(Prior art) It has been known to superfinish the peripheral surface of the shaft of a work such as a crankshaft by oscillation grinding using a grindstone (US Pat. No. 3,562,966). In this case, the oscillation stroke end of the grindstone and It is necessary to form relief grooves in advance at both ends of the shaft portion.

Conventionally, relief grooves deeper than the grinding depth during superfinishing are formed at both ends of the shaft by turning, etc. in the pre-process of superfinishing, but in this case, the relief grooves become weaker parts. However, there are problems in applying it to strong parts such as crankshafts. In order to solve this problem, the applicant of the present application used a thin grinding wheel a at both ends of the shaft portion Wa of the workpiece W to grind the same depth as the grinding depth during superfinishing, as shown in Fig. 1. Previously, we proposed a method in which relief grooves were formed.

(Problem to be solved by the invention) However, in the above-mentioned proposal by Hikari, there is a limit in terms of strength even if the grinding wheel a is made into a book width, so the relief groove should be formed as close to the shaft end as possible. In this case, the grindstone a comes into contact with the fillet rounded part wb at the end of the shaft and damages the rounded part wb, and especially when performing relief groove processing after forming a hardened layer WC by cyanide salt bath treatment etc. Fillet 1-R part wb
There is a problem in that the hardened 1i4wc is removed, resulting in a decrease in strength.

An object of the present invention is to provide a relief groove machining method that solves these problems.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for forming relief grooves at both ends of a shaft portion of a workpiece in a pre-process of super-finishing the peripheral surface of the shaft portion. A belt-shaped polishing cloth is attached to the circular surface of the shaft, and the workpiece is rotated while the parts of the polishing cloth located at both ends of the shaft are pressurized from the back side by a presser piece. It is characterized by forming an escape groove.

(Example) The present invention will be explained with reference to embodiments shown in FIG. 2 and below.

Figure 2 shows a device used to carry out the present invention, which consists of a pair of upper and lower arms (2) pivotally supported on the fuselage (1).
2), and both arms (2) (2) are attached to the aircraft (1).
The tlfl can be closed freely via a toggle mechanism consisting of a slider (4) and a link (5) connected to the cylinder (3) by a cylinder (3) provided in the cylinder (3), and the inner surface of the tip of each arm (2) has a As shown in FIG. 3, a presser piece (6) having a concave cross section and having a pair of opposing protrusions (6aH6a) on both sides is attached to both ends of the shaft part Wa of the journal part of the crankshaft, etc., which is the workpiece W, and Both arms (2> (2
) A belt-shaped polishing cloth (7) is stretched along these holding pieces (6) (6) between the two arms (2) (2).
According to the closing operation of the polishing cloth (7), the polishing cloth (7) is attached to the circumferential surface of the shaft portion Wa from above and below, and the polishing cloth (7) is 8 to 10 kg from the back side by each projection (6a) of the presser piece (6).
It was pressurized at a pressure of about 1/2/ci to be brought into pressure contact with the circumferential surface of each end.

In addition, each of the protrusions (6a) was formed so that the contact surface against the polishing cloth (7) was an arcuate surface with a radius equal to the radius of the shaft portion Wa plus the thickness of the polishing cloth (7). .

In addition, in the illustrated example, the diameter of the opening of the oil hole wd, which opens on the circumferential surface of the shaft portion Wa at the same time as the clearance groove machining, is also increased. A cylinder (8) is attached to the arm (2) so that it can be polished.
A bushing bin (9), which is operated by A cloth 7) is pushed into the mouth edge by the bottle (9) so that its polishing takes place 1.:.

In the drawing, (IG) indicates a guide roller for the polishing cloth (7) provided on each arm (2).

(Function) When machining the relief groove, first, as described above, both arms (2
) Close (2) and apply the polishing cloth (7) to the shaft part Wa of the workpiece W.
Pressure is applied to both ends of the shaft part (6) from the back side of the shaft part (6), and then the workpiece W is rotated. According to this, both ends of the shaft part Wa are ground by the polishing cloth (7),
Here, the width of the protrusion (6a), which is the abutting part of the presser piece (6) against the polishing cloth (7>), can be made as thin as possible, about 2 to 3 m, unlike a grindstone. (6a)
An escape groove A can be formed as shown in FIG. 4 at a position as close as possible to the fillet rounded part wb so that it does not overlap with the fillet rounded part wb. However, the pressing force is not strongly applied to this portion, so that the rounded portion wb is not ground deeply and the hardened layer WC caused by cyanide salt bath treatment or the like is not removed.

In addition, when machining this clearance groove, it is also possible to perform oscillation grinding by oscillating the workpiece W in a minute direction in the axial direction of the shaft portion Wa simultaneously with the rotation of the workpiece W. In this case, the holding piece (6 ) The distance between the two protrusions (6a) (6a) is set somewhat short considering the oscillation.

After forming the relief groove A as described above, in a superfinishing step, the circumferential surface of the shaft portion Wa is oscillated ground using a grindstone to the same depth as the relief groove A, as shown by the two-dot chain line in FIG.

Note that this grinding depth is 2 to 3 μm, and the thickness of the hardened layer WC is usually 0.1 M or more, so there is no problem in terms of strength.

(Effects of the invention! When using the present invention like Riko, a belt-shaped polishing cloth is used,
This is pressurized from the back with a holding piece to form relief grooves at both ends of the shaft of the workpiece. Even if there is a fillet radius at both ends of the shaft, it can be pressed as close as possible to the radius without damaging the radius. This has the advantageous effect of forming an escape groove.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view illustrating the conventional method of machining relief grooves.
Figure 2 shows one of the relief processing devices used to carry out the method of the present invention.
A side view of the example, Fig. 3 is an enlarged cross-sectional view taken along the line ■-■ of Fig. 2,
FIG. 4 is an enlarged cross-sectional view of the main part of a workpiece processed by the method of the present invention. W...Workpiece Wa...Shaft A...Escape groove (6)...Press piece (7)...Outer polishing cloth 2
given name

Claims (1)

[Claims] A method for processing relief grooves formed at both ends of a shaft part in a pre-process of superfinishing the circumferential surface of a shaft part of a workpiece, the polishing method comprising: attaching a belt-shaped abrasive cloth to the peripheral surface of the shaft part; Relief groove machining for super-finishing processing, characterized in that the relief grooves are formed by rotating the workpiece while pressing the parts located at both ends of the shaft of the cloth from the back side with a presser piece. Method.