JPS62208812A - Machining method for piston ring - Google Patents

Abstract

PURPOSE:To reduce tapering cost for piston ring by coupling pistons as stacked between a jig having a predetermined taper and a clamp plate and machining the external surface of the piston rings as tightened and deformed. CONSTITUTION:Many piston rings 9 having an unprocessed external surface 10 are coupled to the shrinked part 3 of a jig 1. Then, when a clamp plate 2 has been tightened to the end of the shrinked part 3 with a bolt 8, the piston rings 9 as stacked come to be tightened between a slope 5 and another slope 7 respectively having a predetermined taper angle and elastically deformed to a form along both shapes 5 and 7. The jig devices 1 and 2 are set, for example, to a work turntable 11 on a milling machine in such a way as to turn about a center axial line 'L' and the externals surface of the piston rings 9 are machined with a milling cutter 12 of cylindrical shape. A piston ring of tapered face to an angle (theta) can thereby be machined to a precise angle very easily and at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing method for forming a taper on the outer circumferential surface of a piston ring fitted to a piston of an internal combustion engine.

In a reciprocating internal combustion engine, the airtightness between the piston and cylinder is maintained by a piston ring fitted to the outer circumferential surface of the piston, and piston rings with various cross-sectional shapes are used. One example is a so-called tapered face type in which the outer peripheral surface, that is, the sliding surface is tapered.

When manufacturing such a taper face type piston ring, in order to form a taper on the outer peripheral surface, conventionally, the first
As shown in the figure, piston ring 01 to be processed
are mounted concentrically on the mandrel 03 via the spacer 02, and while rotating the
A method was adopted in which the outer circumferential surface of the piston ring 01 was cut using a lathe or the like using a tool 05 having a diameter of 4.

°shi and ll1vr However, in the conventional processing method as described above, each piston ring 01 must be attached to the mandrel 03 with the spacer 02 interposed therebetween, which is time-consuming. Furthermore, since the angle of the taper is determined by the shape of the cutting edge of each 5104, it is necessary to prepare a special bit that is carefully finished with a predetermined cutting edge shape, which increases tool costs and processing costs.

1. For this reason, in the method of the present invention, a diameter-reduced portion in the shape of a straight column having an outer circumferential surface substantially matching the inner circumferential surface of a piston ring, and an axially inner end of the reduced-diameter portion are provided. A large number of piston rings are stacked and fitted into the reduced diameter part of the jig, which has a conical slope protruding radially outward from the reduced diameter part, and the sloped surface is provided on the outer periphery of the jig. By fastening a clamp plate having an inclined surface of substantially the same shape and size to the outer end surface of the reduced diameter portion, the mutually stacked piston rings are sandwiched between the two inclined surfaces and shaped to follow the inclined surface. The outer circumferential surfaces of these piston rings are cut to form a straight cylindrical surface parallel to the axis of the reduced diameter portion.

According to the present invention, a large number of piston rings may be stacked as they are without intervening spacers or the like, and then fitted into the reduced diameter portion of the jig. Then, a clamp plate is fastened to the outer end surface of the reduced diameter portion, and the screw ring is sandwiched between two slopes provided on the reduced diameter portion and the clamp plate. These slopes have an angle of inclination equal to the Taber angle to be formed with respect to the end face of the piston ring, so each piston ring has its outer circumference warped along the slope by an angle equal to the Taber angle. deforms elastically. The jig with the screw rings attached in this way is attached to a machine tool, such as a milling machine, and the circumferential surface of the stacked piston rings is cut into a straight cylindrical surface with a predetermined contour using an ordinary helical cutter. . After cutting, each screw ring is removed from the jig, and each piston ring returns to its original flat state due to elasticity, and the cutter cuts the piston ring into a straight column shape. It becomes a tapered surface inclined at a predetermined angle.

The screw l-silling to be processed by the method of the present invention may be an ordinary circular one or an elliptical one having a major axis and a minor axis.

Tsubasa JLJ Hereinafter, the present invention will be described with reference to illustrated embodiments.

FIG. 2 is an exploded side view of the jig device used in the method of the present invention. The jig device consists of a jig 1 and a clamp plate 2, and the jig 1 has a large diameter portion 4 and a reduced diameter portion 3 extending from the large diameter portion 4. The outer circumferential shape of the reduced diameter portion 3 almost matches the inner circumferential shape of the piston ring to be machined.
Moreover, it has a straight column shape so that a large number of these piston rings can be stacked and fitted. The case of machining a normal circular piston ring will be described below. In this case, the reduced diameter portion 3 has a cylindrical shape having an outer diameter approximately equal to the inner diameter of the piston ring. The part where the reduced diameter part 3 transitions to the large diameter part 4 is a conical slope 5, and the angle θ that the slope 5 makes with respect to a plane perpendicular to the axis of the reduced diameter part 3 is equal to the angle θ of the piston ring. The angle of taper to be formed on the outer peripheral surface is 0 (
(see FIG. 6). Clamp plate 2
The jig 1 has a disk shape having approximately the same diameter as the large diameter portion 4 of the jig 1, and a dish-shaped recess 6 is formed on the upper surface. The peripheral edge of the concave portion 6 is a conical slope 7 having the same inclination angle θ as the slope 5, and the central portion is a circular bottom surface 6a that closely contacts the end surface 3a of the reduced diameter portion 3. .

This clamp plate 2 connects the bottom surface 6a to the end surface 3 of the reduced diameter portion 3.
a, and can be fastened to the reduced diameter part 3 with the bolt 8.8. At this time, the slope 5 and the slope 7 protrude outward from the circumferential surface of the reduced diameter part 3, and are parallel to each other. face to face.

When processing piston rings, first, as shown in FIG. 3, a piston ring 9 having an unprocessed outer peripheral surface 10 is prepared.
A large number of these are stacked and fitted into the reduced diameter portion 3 of the jig 1. Next, when the clamp plate 2 is fastened to the end of the reduced diameter part 3 with the bolt 8, the stacked piston rings 9, 9... are tightened between the slopes 5 and 7, as shown in FIG. It is elastically deformed into a shape along the slope 5°7. Although the angle θ is exaggerated in the drawings, it is actually about 1 to 36, so the above modification can be performed relatively easily. As shown in FIGS. 4 and 5, the outer circumferential surface 10 of each piston ring 9 after deformation is inclined at an angle θ with respect to the axial direction, and the lower edge protrudes outward from the upper edge. The outer peripheral surface has a serrated cross section as a whole.

A jig device in which a large number of piston rings 9 are stacked and deformed as described above is mounted on a workpiece rotating table 11 on a milling machine, for example, so as to rotate around the central axis of the piston rings 9. .

Then, while rotating the piston ring 9, cutting is performed using a cylindrical milling cutter 12 having a rotation axis L' parallel to the center axis, and the overall shape of the stacked piston rings 9, 9... The outer peripheral surface is a cylindrical surface as shown by the broken line C in FIG. This cylindrical surface forms the original outer circumference 10 of the piston ring 9 and also the upper surface 9 of the piston ring 9.
Needless to say, it is inclined by an angle θ with respect to a.

When the piston ring 9 that has been cut is removed from the jig 1, the piston ring 9 returns to the flat state shown in FIG. 6 due to its elasticity, and the cylindrical surface indicated by the broken line C in FIG. The tapered surface 13 is inclined at an angle θ with respect to the end face of each of the screws 1 to 9.

FIG. 7 shows a modification of the jig used in the method of the present invention. In this modification, the screw 1-shilling is 98 and 9b 2
VtR# is divided into groups. 1a is a first jig similar to the jig 1 in the embodiment described above, and m second jigs 1b are attached to this first jig 1a. The second jig 1b has a slope 7b similar to the slope 7 of the clamp plate 2 on the upper surface of the large diameter portion 4b, and the piston ring 9a has a slope 7b on the upper surface of the large diameter portion 4b.
is tightened between the slope 5a of the jig 1b and the slope 7b of the jig 1b, and is deformed. The jig 1b is also provided with a slope 5b similar to the slope 5 of the jig 1 described above, and by tightening the ramp plate 2 to the jig 1b, which is similar to the slope 5 of the jig 1 described above, the gap between the slope 5a and the slope 7 is A piston ring group 9b is sandwiched between. By interposing the slopes 7b and 5b of the jig 1b between the piston rings stacked in large numbers in this manner, each piston ring can be more easily and accurately deformed.

Although the case where a circular piston ring is processed has been described above, it is also possible to process a non-circular piston ring, such as an oval or oval-shaped piston ring, by the method of the present invention. In this case, the profile of the cross section of the aforementioned reduced diameter portion 3 and the slope 5.7 is oval to match the piston ring, and the reduced diameter portion 3 becomes a straight columnar body having such a cross section. The cutting process is performed using an NC milling machine, and the rotational axis L' of the milling cutter 12 is moved along the arrow a according to the rotation angle around the axis of the screw 1 and the sill 9 in FIG.
It is sufficient to advance and retreat with respect to the axis as shown in . Of course, the axis may be moved back and forth with respect to the axis L'.

l1 animal 113- As described above, in the present invention, a straight column-shaped reduced diameter portion having an outer circumferential portion that approximately coincides with the inner circumferential surface of the piston ring;
A large number of piston rings are stacked on the reduced diameter part of the jig, which has a conical slope extending outward in the radial direction from the reduced diameter part at the inner end in the axial direction of the reduced diameter part. By fitting a clamp plate having a slope substantially the same shape and size as the slope on the outer periphery to the outer end surface of the reduced diameter portion, the piston rings stacked v1 on each other are fixed to the two slopes. The outer circumferential surfaces of the piston rings are sandwiched between them and deformed into a shape that follows the slope, and the outer circumferential surfaces of these piston rings are cut to form a straight cylindrical surface parallel to the @ line of the reduced diameter portion. Since the taper is formed in the piston ring, it is possible to process the taper extremely easily and at an accurate angle on each of the large number of piston rings.・Furthermore, there is no need for special tools that are carefully finished to form a predetermined tip shape, reducing processing costs.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the conventional piston ring processing method;
Fig. 2 is an exploded side view showing an example of a jig device used in the method of the present invention, Fig. 3 is a side view showing a state in which a piston ring is fitted to the jig, and Fig. 4 is a side view showing various parts during cutting. Figure 5 is an enlarged sectional view showing the state of the piston ring during cutting, Figure 6 is a side view showing the state of the piston ring after machining, and Figure 7 is a side view showing the state of the piston ring after machining.
The figure is a sectional view showing a modified example of the jig device. 1...Jig, 2...Clamp plate, 3...Reduced diameter part,
4...Large diameter part, 5...Slope, 6...Concave part, 7...
・Slope, 8... Bolt, 9... Piston ring, 1
0... Outer peripheral surface, 11... Turntable, 12... Milling cutter, 13... Tapered surface.

Claims (1)

[Claims] A method for forming a taper on the outer circumferential surface of a piston ring, comprising: a straight column-shaped reduced diameter portion having an outer circumferential surface that substantially matches the inner circumferential surface of the piston ring, and the reduced diameter portion at an axially inner end of the reduced diameter portion. A large number of piston rings are stacked and fitted into the reduced diameter part of the jig, which has a conical slope extending outward in the radial direction from the center of the jig, and the outer peripheral part has a conical slope substantially the same shape as the slope. By tightening a clamp plate having slopes of the same size to the outer end surface of the reduced diameter portion, the piston rings stacked on top of each other are sandwiched between the two slopes and deformed into a shape along the slopes. A method for processing a piston ring, comprising cutting the outer circumferential surface of the piston ring so as to form a straight cylindrical surface parallel to the axis of the reduced diameter portion.