JPS6240424B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a piston ring for an internal combustion engine, and more specifically, the present invention relates to a method for manufacturing a piston ring for an internal combustion engine, and more specifically, the present invention relates to a method for manufacturing a piston ring for an internal combustion engine. It relates to a method of applying

In recent years, the performance of internal combustion engines has improved steadily, with high output and
With the trend toward higher speeds, piston rings are required to satisfy these conditions, and are also required to withstand long-term use. Particularly in diesel internal combustion engines, piston rings are increasingly required to have seizure resistance, abrasion resistance, and scuffing resistance as diesel internal combustion engines increase in speed due to the occurrence of carbon suits.

Conventionally, improved piston rings are known in which the outer peripheral surface that contacts the cylinder liner is plated with chromium (Cr) or sprayed with molybdenum. Among these, chrome-plated piston rings have good wear resistance, but do not have good seizure resistance with the mating cylinder liner cast iron material.
It has the disadvantage of being prone to seizure and scuffing. For these reasons, molybdenum thermal spraying, carbide thermal spraying, ceramic thermal spraying, etc. have been adopted or are being considered, but because there are various restrictions on the thermal spraying process in manufacturing, many processes are required and the cost is high. It is also a contributing factor.

That is, since the piston rings are too small to be thermally sprayed one by one, a large number of piston rings 1, 1, 1... are stacked together to form a cylindrical body 11 as shown in FIG. The method of thermal spraying on the outer periphery of the cylindrical body 11 and then separating it into individual rings has been conventionally carried out because it is economical. There was a problem with not being able to split it into individual rings. Therefore, conventionally, a ring groove 2 is formed at the center of the outer circumference of the ring as shown in FIG.
The actual situation is that a sprayed layer 3 is formed within this ring groove 2.

In this conventional method, as shown in Fig. 1, piston rings 1, 1...... are stacked to form a cylindrical body 11, and then the cylindrical body 11 is rotated around holders 4, 4 at both ends. , 1 of ring 1 as shown in Figure 4A.
After cutting a ring groove 2 into each book and shotplast, preheat and thermal spray (Fig. 4B).
The sprayed surface was ground until a part of the ring surface was scraped off (up to the X-X line in Figure 4B), and the cylindrical bodies were individually separated to obtain the sprayed ring (Figure 4). C).

However, when using the above conventional method, compared to the chrome plating method, there is a disadvantage that the number of processes such as groove processing and thermal spray layer grinding increases, and the sliding surface of the product decreases. Also, since it is more expensive than the chrome plating method in terms of cost,
The reality is that thermal sprayed rings are not used in Japan except for special vehicles, despite their advantages in terms of performance and durability.

An object of the present invention is to provide a new manufacturing method that allows thermal spray piston rings to be manufactured in mass production at low cost without grooving rings in the process of manufacturing thermal spray rings.

In the present invention, at least one end of the outer peripheral sliding surface of a piston ring made of cast iron or steel base material is chamfered by 0.1 to 0.3 ^c , and a large number of such rings are chamfered so that the chamfered portions are in the same direction. The rings are stacked one on top of the other around a common axis to form a cylindrical body, and the cylindrical body is thermally sprayed at an angle that prevents thermal spray particles from adhering to the side ends or one chamfer of the ring.

By performing thermal spraying after chamfering in this manner, it is possible to separate the cylinder state into individual piston rings after thermal spraying. Therefore, the removal by grinding after thermal spraying only requires processing the surface roughness of the sprayed surface, making it possible to manufacture thermal sprayed rings with excellent scuffing and seizure resistance at a cost comparable to that of chrome plating. .

Next, the present invention will be explained with reference to FIGS. 5A to 5C.

First, as shown in Fig. 3, piston rings with a chamfer 5 on one end of the outer circumferential sliding surface are stacked together with the chamfer 5 facing in the same direction to form a cylindrical body 11, and only the outer circumferential surface is processed. After finishing it to the predetermined dimensions (Fig. 5A), it is shot plus, preheated, and thermal sprayed. Thermal spraying is performed by rotating the cylindrical body 11 about its common axis and spraying from the direction opposite to the surface of the chamfer 5 so that the spray particles do not adhere to the side end 6 of the ring 1 (fifth Figure B). The upper surface of the thermally sprayed layer 3 of the cylindrical body thus thermally sprayed is subjected to finish grinding to obtain the desired thermally sprayed piston ring (FIG. 5C).

In thermal spraying, if the thermal spray coating on the outer peripheral surface has poor adhesion to the base material, a metal material with excellent adhesion and heat resistance is sprayed as a base thermal spray, and then a coating with wear resistance, seizure resistance, and scuffing resistance is applied. It is preferable to form a thermal spray coating with excellent properties on the outer peripheral surface. Further, the chamfering process of the ring described above may be performed after forming the ring into a cylindrical body.

When comparing the present invention with the conventional method, in order to obtain a product ring with a thermal spray coating thickness of 0.2 mm or more, in the conventional method, the ring groove should be 0.25 to 0.3 mm, taking into account machining allowance.
mm, and the sprayed layer thickness is 0.25mm
More than that is required. At this time, the thermal spray coating is as shown in Fig. 4B.
As shown in the figure, since it adheres to areas other than the ring groove, the grinding allowance after thermal spraying is 0.25 to 0.3 mm thick of the thermal spray layer.
and ring machining allowance of 0.05 to 0.1mm, 0.3 to 0.4
mm, and grinding is time-consuming. On the other hand, according to the method of the present invention, in addition to chamfering, 0.25~
With thermal spraying of 0.3 mm, the machining allowance is only 0.05 to 0.10, which is less than 1/4 of the conventional machining allowance, which can greatly reduce the amount of grinding.

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

Example 1 As shown in FIG. 7, a plurality of piston ring base materials 1 made of spheroidal graphite cast iron having a cross-sectional shape with a chamfer 5 at an angle of 60 degrees with respect to the axis 7 on both ends of the outer peripheral surface are prepared, and the base materials 1 are stacked one on top of the other. Together, a cylindrical body 11 is formed, and while the cylindrical body 11 is rotated about the axis 7, the outer circumferential surface of the ring is cut to a predetermined dimension that takes into account the thickness of the thermal spray coating, and then the outer circumferential surface is shot plus. Preheat. Next, molybdenum is gas-sprayed onto the cylindrical body 11 rotating about the axis 7 using a thermal spray gun 8 having an angle of 50 degrees with respect to the axis 7 to coat it to a predetermined thickness that takes into account the grinding machining allowance. (Figure 6). Thereafter, the outer peripheral surface was ground using a cylindrical grinder and finished to the product dimensions to complete the thermal sprayed piston ring.

If the angle to the axis of the thermal spray gun is 60° or more, the piston ring cannot be separated after grinding, as shown in the reference example, and if the angle is 30° or less, the adhesion of the molybdenum to the base material may be affected. Since the angle of the spray gun was set to between 30° and 60°, piston rings could be produced.

The product dimensions and thermal spraying conditions for this piston ring are as follows.

Piston ring nominal diameter 90mm, thickness 3mm, width
2.5mm, outer circumferential chamfering ^0.2c (60° to the axis), thermal spray coating thickness 0.2 to 0.25mm, gas spraying by METCO in the US
The process was carried out using a ``3K'' gas spraying machine under the following conditions.

Oxygen gas flow rate: 95ft ³ /hour Acetylene gas flow rate: 45ft ³ /hour Spraying distance: 100mm Molybdenum 1/8 inch, reference example of using wire Rod The same cylindrical body as in Example 1 was attached to a thermal spray gun with an angle of 90° to the axis. When molybdenum was gas-sprayed, a molybdenum spray coating was formed on the chamfered portions of both ends of the outer peripheral surface of the ring, and the piston rings could not be separated one by one even after grinding.

Example 2 Instead of chamfering both ends of the outer peripheral surface of Example 1, a cylindrical body was formed from a piston ring base material having a cross-sectional shape with a 0.2 ^c chamfer on only one side as shown in FIG. Cutting, shot blasting, and preheating the outer peripheral surface of the ring, then
A piston ring was completed by spraying molybdenum using a thermal spray gun with an angle of 0.2 degrees, followed by grinding and finishing to the product dimensions. The piston ring was easily separated after grinding, and a thermally sprayed piston ring with good wear resistance was obtained.

[Brief explanation of the drawing]

Figure 1 is a side view of the piston ring cylindrical body, Figure 2 is a side view of the piston ring cylindrical body;
The figure is a partially cut-off perspective view of a piston ring made by a conventional method, FIG. 3 is a partially cut-off perspective view of a piston ring base material that has been chamfered, and FIGS. Cross-sectional view of part a, Figures 5A to C
6 is a sectional view of the main part a of the cylindrical body for explaining the present invention, FIG. 6 is a side view of the cylindrical body for explaining the spray angle, and FIG. 7 is for explaining another embodiment of the present invention. FIG. 6 is a sectional view of part b of FIG. In the figure, 1...piston ring, 11...tubular body, 2...groove, 3...sprayed layer, 5...chamfer, 7
...Axis of the cylindrical body, 8...Thermal spray gun.

Claims (1)

[Claims] 1. A method for obtaining a thermally sprayed piston ring by stacking a large number of piston rings to form a cylindrical body and spraying metal, ceramic, etc. on the outer periphery of the cylindrical body, in which one or both ends of the outer periphery of the piston ring are chamfered, A thermal sprayed piston ring characterized by stacking piston rings to form a cylindrical body so that the chamfered portions are in the same direction, and spraying from an angle that prevents thermal spray particles from adhering to the side end of the piston ring or one of the chamfered portions. manufacturing method.