JPS61152330A - Preparation of piston ring - Google Patents

Abstract

PURPOSE:To permit the minute beveling for the lower-edge corner part of the outer peripheral surface of a taper ring by carrying-out machining, chrome plating treatment, and grinding work, and then polishing the party by using a buffing wheel which possesses elasticity and fine polishing efficiency. CONSTITUTION:The first process is for machining, and large beveling work is carried-out for the upper-edge corner part 14 on the outer peripheral surface 12 of a piston ring 10, and small beveling work is performed for the lower-edge corner part 16. In the second process, an abrasion-resistive layer 20 consisting of chrome plating, etc. is formed onto the outer peripheral surface 12. In the third process, the outer peripheral surface 12 is formed into a taper, and the grinding work for forming the lower-edge corner part 16 into an arcuate angle is carried-out. At last, polishing is applied by using a buffing wheel 22, and minutely beveled part is formed at the lower-edge corner part 16, and if necessary, lapping finishing is performed. The above-described method is suitable for mass production, and the blowing-out of combustion gas from the bevelled part at the outer peripheral lower edge part is little on a product.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a piston ring for internal combustion a, particularly a taper face type piston ring (hereinafter abbreviated as a taper ring).

(Prior Art) In recent years, high-speed internal combustion engine flywheels have come to be required to have a tapered ring with a slight inclination on the sliding surface with the cylinder for reasons of performance.

In other words, the outer circumferential surface is tapered to reduce the contact area with the cylinder compared to the old trend, and the comb shape increases the bottom pressure, improving conformability at the beginning of operation, and making it possible to stabilize oil consumption and probe in a short time. It became so. Furthermore, the tapered ring facilitates the formation of an appropriate oil film on the sliding surface during the piston's upward stroke, and has the effect of sweeping away excess oil during the downward stroke.

In addition, if the taper starting point, i.e., the bottom corner of the outer peripheral surface, is left at an acute angle, the taper ring will cause corner chipping or scratches on the inner wall of the cylinder, which is undesirable. In order to create deeper scratches on products, the corners are usually chamfered to a depth of about 0.2 mm.

The chamfer size of this lower end corner part needs to be very small in order to further reduce the blow pie, but especially on the outer circumferential surface and the lower surface that sandwich the corner part, the chamfer size is 0.1111.
! The following manufacturing methods were used to form the minute chamfer at the bottom.

i) After chamfering the outer circumferential surface by cutting with a cutting tool or the like, a wear-resistant layer such as plating is formed, and then grinding is performed to form a tapered surface (first
Figures (a) to (c)).

11) If a sufficiently small chamfer cannot be obtained by the method i) described above, the bottom surface of the ring is roughly ground following the step i) to form a minute chamfer.

1if) After forming a wear-resistant layer such as plating, the bottom corner is made into an acute angle by taper grinding, and then fine chamfering is performed (FIGS. 2(A) to 2(C)).

(Problems to be Solved by the Invention) The conventional methods described above have the following problems. That is, in method i), it is difficult to make the thickness of the wear-resistant layer 7 and the amount of taper grinding constant, and the final finished dimensions tend to vary.

Method 11) requires a lot of man-hours and is not suitable for mass production.

Furthermore, in the method iii>, it is difficult to achieve the target minute chamfer size only by the final chamfer grinding, and the number of man-hours increases.

In view of the above, an object of the present invention is to provide an effective manufacturing method for forming a minute chamfer, particularly a chamfer of Q, 1 JIIl or less, at the corner portion of the lower end of a tapering ring.

(Means for Solving the Problems) A method for manufacturing a piston ring according to the present invention that enables the above-mentioned object is such that the outer peripheral surface of the ring is vertically asymmetrical at the corner portions of the upper end and the lower end, and the lower end is smaller than the upper end. A first step of performing machining such as cutting to form a chamfer, a second step of forming a wear-resistant layer on the outer peripheral surface, and forming the outer peripheral surface into a tapered shape and making the bottom corner part an acute angle. The present invention is characterized by comprising a third step in which a grinding process is performed as shown in FIG.

Further, after buffing, a lapping finish is further performed if necessary.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

First, as shown in FIG. 3, on the outer circumferential surface 12 of the ring 10, the upper and lower corner portions 14 and 164 are cut so that chamfers are vertically asymmetrical and the lower corner portion 16 is smaller than the upper corner portion 14. 18 etc., but this chamfering is to improve the adhesion condition when forming a wear-resistant layer such as hard chrome plating in the subsequent process, and to make it easier to take apart after plating. It is. The amount of vertically asymmetrical chamfering is carefully set in consideration of the thickness of the wear-resistant layer, the subsequent taper grinding, and the size of the micro chamfer, but in general, the lower end corner portion 16 is 1/1/2 of the upper end corner portion 14. It is appropriate to make it 3 to 1/2 the size.

Next, as shown in FIG. 4, after forming a wear-resistant layer 20 such as hard chrome plating, the corner portion 16 at the lower end of the outer peripheral surface is ground into an acute angle to form a tapered shape.

Finally, as shown in FIG. 5, a buff 22 is applied to the outer circumferential surface 12 and the corner portion 16 at the lower end of the outer circumferential surface
Form a minute chamfer on the surface. By applying the buff 22 which has elasticity and has precise polishing ability, the buff 22 can be polished as shown in the figure.
As shown, it wraps around the bottom surface of the ring 4, and the corner part 1
O, l respectively from the acute angle apex on the outer peripheral surface and lower surface sandwiching 6.
A chamfer with a minute roundness of n or less is formed.

If necessary, after buffing, a normal lapping finish is performed to improve the perfect circularity of the ring.

(Example) The ring diameter was 137 mm by the method shown in Figure 3.

A cast iron piston ring material with an axial width of 3.5 mm and a radial width of 5.4 mm has a curvature radius of 0.35 ml at the upper end and a curvature radius of 0.15 at the lower end by cutting with a cutting tool.
A chamfer of m1 was formed.

Next, after forming a hard chrome plating layer with a thickness of 0.23 mm+ on the outer circumferential surface, the upper end of the outer circumferential surface has a thickness of 0.1 mm+ by the method shown in FIG. 11 m, the lower end was ground by 0.09111111 to form a tapered surface with an inclination angle of 50 minutes, and the lower end corners were made into acute angles.

Next, as shown in FIG. 6, between each washer 24.
24,... are set between the centers of the polishing machine 10. When the buff 22 set on the rotating shaft is applied to the outer peripheral surface of 10,... and both are rotated in opposite directions. At the same time, by moving the buff 22 in the direction of the rotation axis, a curved chamfer was formed at the lower corner of the outer circumferential surface of the ring, with 0.07111111 removed from the acute apex on the outer circumferential surface.

Finally, by performing finishing polishing by lapping, the removed portion at J5 on the outer circumferential surface is 0.0411111. A chamfer of 0.0311IIll was formed from the apex of the intersection angle on the lower surface.

The conditions for buffing were as follows.

Work rotation speed: 330 rpm Buff rotation speed: 1500 rpm Buff feed movement speed: 10 m + 11/S Buffing material Commercially available nonwoven fabric impregnated with aluminum dioxide (effects of the invention) As described above, the method of the present invention When chamfering the lower end corners, buff polishing, which is elastic and has precise polishing ability, is used, making it possible to create minute chamfers, making it a method suitable for mass production. The tapered ring manufactured by the present invention can particularly reduce blow-by of combustion gas from the chamfered portion at the lower end of the outer periphery.

[Brief explanation of drawings]

FIGS. 1 and 2 show a conventional method for manufacturing a taper ring. FIGS. 3 to 6 show the manufacturing method of the present invention in the order of steps. Explanation of symbols 10... Piston ring, 12... Outer circumferential surface, 16...
...Bottom corner, 22...buff.

Claims (3)

[Claims] (1) A method for manufacturing a piston ring having a tapered contact surface, the method being such that a chamfer is formed at the corners of the upper and lower ends of the outer circumferential surface with a vertically asymmetrical chamfer that is smaller at the lower end than at the upper end using a machine such as cutting. A first step of processing;
a second step of forming a wear-resistant layer on the outer circumferential surface; a third step of grinding the outer circumferential surface so as to make it tapered and make the bottom corner part an acute angle; and buffing the outer circumferential surface. A method for manufacturing a piston ring, comprising a fourth step of forming a minute chamfer at the corner of the lower end. (2) The method for manufacturing a piston ring according to claim 1, wherein after the fourth step, the outer peripheral surface is further subjected to lapping finishing. (3) The minute chamfer formed at the corner of the lower end of the outer circumferential surface in the fourth step is a curved chamfer of 0.1 mm or less from the acute apex on the outer circumferential surface and the lower surface that sandwich the corner, respectively. A method for manufacturing a piston ring according to claim 1.