JPS59138757A - Piston ring and manufacturing thereof - Google Patents

Abstract

PURPOSE:To obtain a piston ring which is made of a cheap base material but has the properties of high seizing-resistance, scuffing-resistance and wear-resistance, by forming a flame sprayed layer in an annular groove formed in the center section of the outer peripheral surface of the piston ring, and as well by coating a highly wear-resistant material on both lateral parts of the annular groove. CONSTITUTION:An annular groove 5 is formed in the center section of the outer peripheral surface of a steel piston ring base material 1 during the drawing process of the latter, and the outer peripheral surface of the base metal 1 is subjected to the flame spraying of a metal such as, for example, Mo, Ni, Cr or Fe, to form a flame sprayed layer 2. Thereafter, not only the flame sprayed layer in the boundry section but also the base material 1 are slightly polished during its polishing step to expose the base material 1 on both sides 6 of the annular groove 5 so that the base material 1 is made in a slightly tapered shape. The flame sprayed layer 2 is left only in the annular groove 5 so that it projects largely more than both side sections 6. After coating a chromium plated layer 7 on the peripheral surface of the base material 1, the part coating the flame sprayed layer is removed during its barrel lapping step, and therefore, the chromium plated layer 7 is left only in the part in the vicinity of the lateral part thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston ring for an internal combustion engine, and more particularly to an improvement in an inlaid thermal sprayed ring having a thermal sprayed layer within an annular groove formed along its outer circumferential surface.

Among piston rings, particularly for G and F rings which are subjected to a large heat load, thermal sprayed rings are often used because they have various properties and can easily be coated on all metal sliding surfaces. However, in conventional inlaid thermal sprayed rings, the base material is exposed on both sides of the annular groove in which the sprayed layer is formed, that is, on the upper and lower parts of the sliding surface, so there is a possibility that this base material may come into sliding contact with the cylinder gear. This may cause scuffing and wear. For this reason, it is not possible to freely select the material for the base material of the inlaid thermal spray ring, and cast iron, which is compatible with the bore, is widely used. However, when a di-inlaid thermal spray ring is manufactured from cast iron, there is a problem in that the manufacturing cost increases due to the necessity of machining an annular groove in which to embed the thermal spray layer.

On the other hand, steel rings, which do not require special groove machining and are highly mass-producible, generally have poor compatibility with cylinder bores, and 74? Because it is easy to cause scuffing and abrasion of the
Application is limited.

The present invention aims to make it possible to manufacture an inlaid thermal sprayed ring that has sufficient performance in terms of seizure resistance, scuff resistance, wear resistance, etc. using an inexpensive base material such as steel. It was done for a purpose.

In the first invention, an annular groove is carved along the center of the outer circumferential surface, and a sprayed layer is formed in the annular groove, and
The present invention provides a piston ring characterized in that both sides of the annular groove are coated with a wear-resistant material.

A second invention relates to a method for manufacturing the above-mentioned piston ring. a thermal spraying step of forming the entire thermal sprayed layer on the surface, a polishing step of removing the thermal sprayed layer on the sides of the annular groove to expose the base material on the side, and applying a wear-resistant material to the outer peripheral surface. It is characterized in that a coating step for coating and a removal step for removing the wear-resistant material coated on the surface of the sprayed layer in the annular groove are performed in sequence.

A third invention relates to another method of manufacturing the piston ring.
This manufacturing method includes a coating step of coating the outer circumferential surface of an annularly formed member with a wear-resistant material, and (2) carving an annular groove along the center of the outer circumferential surface to expose the base material. a groove processing step, a thermal spraying step of forming a thermal sprayed layer on the outer peripheral surface where the groove has been formed, and a thermal spraying step of removing the thermal sprayed layer on the side of the annular groove from the thermal spraying layer to obtain a wear-resistant It is characterized by sequentially performing a removal step to expose the elastic material.

The present invention will be explained below with reference to the illustrated embodiments.

A steel wire rod to be drawn is formed with grooves on one side during this outer drawing process, and then bent into an annular shape with the grooves on the outside and cut. As shown in FIG. 1, the ring member 1 formed into an annular shape is made into a cylindrical body by polymerizing a plurality of pieces, and is fitted and supported by a rod-shaped holder (not shown). After shot blasting, the outer peripheral surface of this cylindrical body was coated with Mo and Ni.
, Or +Fe, etc. are thermally sprayed to form a thermal sprayed layer 2.

This sprayed layer 2 is polished by grinding the grindstone 3 while rotating it around the axis 9, and as shown in FIG. Borders are removed. Grindstone 3 is used to sharpen this boundary area more.
An annular raised portion 4 is formed in a portion corresponding to this boundary portion. During this polishing process, not only the sprayed layer at the boundary but also the base material of the ring member 1 is slightly polished.
As a result, both sides 6 of this annular groove 5 expose the base material and are slightly tapered, and the sprayed layer 2 remains only within the annular groove 5 and protrudes beyond the both sides 6.

When the thermal spray layer at the boundary portion is removed in this way, each ring member 1 is separated from each other, and as shown in FIG. A chromium plating layer 7 with good compatibility is coated. This chrome plating layer 7 is applied to the thermal spray layer 2 in the parel lag process described below.
As a result, the chrome plating layer 7 remains only on the side 6 and in the vicinity of the side 6 of the sprayed layer 2, as shown in FIG.

Figure 5 shows an outline of the equipment for carrying out the parallel wrapping process.
This device includes a hole 8 having a slightly larger diameter than the ring member 1 on which the plating layer shown in FIG. and a pair of restraining plates 10.11 fixed to the support rod 9 so as to be inclined in mutually opposite directions. The ring member 1 is fitted onto the support rod 9 between these holding plates 10 and 11. Thus, when the support rod 9 is raised and lowered while being rotated around its axis, when descending, the ring member 1 rotates while being inclined following the upper restraining plate 10, and conversely, when ascending, the ring member 1
follows the lower restraining plate 11 and rotates while being inclined. As a result, the protruding portion of the chrome plating layer 7 of the ring member 1, that is, the portion on the sprayed layer 2, slides against the inner wall of the hole 8 and is removed, and the portion of the sprayed layer 2 is exposed in a barrel shape. . Note that the angle of inclination of the holding plates 10 and 11 and the hole 8
Needless to say, the diameter of the chrome plating layer 7 on the side portion 6 is determined to be such that the chrome plating layer 7 on the side portion 6 is not removed.

In the piston ring manufactured as described above, a chip-shaped chromium plating layer 7 is formed on the surface of the base material above and below the sliding surface, and the sprayed layer 2 is the most protruding.

Therefore, this ring has a small amount of deflection during operation (even if parts other than the sprayed layer 2 come into contact with the cylinder bore,
? It is effective in preventing the occurrence of ascarafes, etc., and can significantly improve durability compared to conventional inlaid thermal spraying rings.

6 to 8 show a second method of manufacturing piston rings. In this manufacturing method, the steel wire to be drawn does not have grooves as in the first manufacturing method, but is first bent and cut. Next, as shown in FIG. 6, the outer circumferential surface of the ring member 1 is coated with chrome plating Jso 7, and then a groove machining process is performed to form an annular groove in the center of the outer circumferential surface as shown in FIG. 5 is polished. As a result, the plating layer or the annular groove 5 remains only on both sides. The outer peripheral surface of the ring member 1 having the annular groove 5 formed thereon is shot blasted, and then a metal such as Mo + Nt + Cr is thermally sprayed in the same manner as in the first manufacturing method. This metal sprayed layer mainly consists of the annular groove 5.
However, the plating layer 70 portions on both sides of the plating layer 70 are also coated. The sprayed layer on the plating layer 7 is removed when the outer peripheral surface is formed into a barrel shape in the barrel lano process. As a result, as shown in FIG.
A piston ring is manufactured which has a thermally sprayed layer 2 therein and a plating layer 7 on both sides thereof.

Note that in the piston ring manufactured by the first manufacturing method, the plating layer 7 may be slightly coated on the side 6 side of the thermal sprayed layer 2 (see Fig. 4); In the piston ring manufactured by this method, the thermal spray layer 2 is not coated with a plating layer.

In any of the above manufacturing methods, a shot blasting step is performed before the thermal spraying step, but if the adhesion strength of the thermal sprayed layer is sufficient, this shot blasting step can be omitted. That is, this is a case where a large number of micropores can be formed to tightly adhere the sprayed layer to the surface of the base material.

In addition, if there is a risk that the plating layer 7 will be excessively worn due to ring tilt due to wear on the upper and lower surfaces of the piston ring, it is recommended to use SUS steel as the base material and to apply tuftride treatment to the upper and lower surfaces. I like it.

Further, the plating layer 7 may be formed by composite plating, or Teflon may be applied instead of the plating layer.

It goes without saying that the present invention can also be applied to keystone rings.

As described above, the present invention has the advantage that it is possible to obtain an inexpensive inlaid thermal spray ring with sufficient durability.

[Brief explanation of the drawing]

Figure 1 is a partial cross-sectional side view showing the polishing process in an embodiment of the first manufacturing method, Figure 2 is a cross-sectional view of the main part of the ring member after the polishing process, and Figure 3 is a chrome-plated ring. FIG. 4 is a cross-sectional view of the main part showing an example of a piston ring manufactured by the first manufacturing method; FIG. 5 is a schematic view showing an apparatus for performing barrel lapping. FIG. 6 to FIG. 8 show the ring member at each step in the embodiment of the second manufacturing method, and FIG.
Fig. 7 shows the main part of the ring member formed with the annular groove.
The top view and FIG. 8 are cross-sectional views of essential parts showing an example of a piston ring manufactured by the second manufacturing method. 2... Thermal spray layer, 5... Annular groove, 6... Side part, 7...
...Chrome plating layer. Patent Applicant Toyota Motor Corporation Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Kyo Nakayama Akira Yamaguchi Figure 1 Figure 2 Figure 3 []
M94 gu:] Nini γ゛5・□ Figure 6 Figure 7] Figure 8

Claims (1)

[Claims] 1. An annular groove is carved along the center of the outer circumferential surface, a sprayed layer is formed on the annular groove, and both sides of the annular groove are coated with a wear-resistant material. A piston ring characterized by: 2. The piston ring according to claim 1, wherein the sprayed layer substantially protrudes beyond the coating layer made of the wear-resistant material on both sides of the annular groove. 3. A groove processing step of carving an annular groove along the center of the outer peripheral surface of the annularly formed material, a thermal spraying step of forming a thermal spray layer on the outer peripheral surface, and a thermal spraying step of forming the annular groove in the thermal spray layer. a polishing step of removing the sprayed layer on the side to expose the base material of the side; a coating step of covering the outer peripheral surface with a wear-resistant material;
A method for producing a piston ring, comprising sequentially performing a removing step of removing the wear-resistant material coated on the surface of the sprayed layer in the annular groove. 4. The method of manufacturing a piston ring according to claim 3, wherein the surface of the sprayed layer in the annular groove formed by the polishing step also protrudes from the sides of the annular groove. 5. A coating step in which the outer peripheral surface of the annularly formed material is coated with a wear-resistant material; and a groove processing step in which an annular groove is carved along the center of the outer peripheral surface to expose the base material. , a thermal spraying step of forming a sprayed layer on the outer peripheral surface where the groove is formed; and a removing step of removing the thermal sprayed layer on the side of the annular groove to expose the wear-resistant material on the side. A method for manufacturing a piston ring characterized by sequentially performing the following steps. 6. The piston ring manufacturing method according to claim 5, wherein the surface of the sprayed layer after the removal step protrudes beyond the surface of the wear-resistant material on the side of the annular groove.