JPS6293571A - Piston ring - Google Patents

Abstract

PURPOSE:To improve scuffing resistance and wearing resistance in a cylinder and a ring groove, by coating the surface of a piston ring in which steel material conforming to SKH51-54 is molded to apply heat treatment to hardness of Hv600-900. CONSTITUTION:A piston ring 4 is manufactured in such a manner that after high speed steel SKH51-54 is molded, this molded material applies heat treatment so as to provide its hardness of Hv600-900. And said piston ring 4 forms its sliding peripheral surface 8 to be coated by the ion plating method with a coating film 5a of TiN. Consequently, the piston ring 4, while holding its hardness and durability, prevents further a cylinder bore 1 and/or a ring groove 3 from their wearing and damage.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an internal combustion engine in which a coating film having scuff resistance and four-wear resistance is formed on a steel ring (piston ring body) having high hardness (My 600 or more). This is related to piston rings.

(Prior Art) Conventionally, piston rings have been made of cast iron such as spheroidal graphite cast iron (FCJ), spring steel (5WO8C-V), tool steel (
SK-5) is quenched and tempered, 13Cr and 17
A steel/IJ ring made of Cr stainless steel with gas filling is used. .

On the other hand, 7s/Daboa is cast iron (PCz3) father QmaA, /-
In recent years, A390 alloy and FRM (aluminum alloy casting) At thread materials have become mainstream due to issues such as weight reduction.

However, with At yarn materials, it is difficult to obtain a good surface condition because the 49 At matrix plastically flows during the finish honing process.

Therefore, the surface of the piston ring that slides on the wall surface of the cylinder bore is subjected to Cr plating, channel porous Cr plating, gas nitriding, etc. However, with these treatments alone, scuffing, which is a type of micro-wear, occurs in the piston ring at the stage in the initial stage of use.

For this reason, the cylinder bore is usually finish honed and the surface roughness is RzQ, 5 to 1. After finishing to about 0μ and making the surface smooth, the elongated matrix was extracted by ECM (electrolytic polishing) treatment, and the recesses with a depth of just over 1μ were completely formed.
Initial scuffing is prevented by the oil trap effect of the recess.

1.In order to eliminate the drawbacks of conventional Cr-plating and A4O thermal spraying, the sliding motion of the piston ring is coated with TiN, TiN, and
There is one in which a coating made of a carbide such as Tic or CrN is formed (see Japanese Patent Application Laid-Open No. 57-57868-1ij).

Further, 1. At least the sliding outer peripheral surface of the piston ring is coated with a titanium nitride (TiN) coating by ion plating, and the hardness of the coating is 1 (v1300 or more, thickness 3~
There is a piston ring with a roughness of 20μ and the sliding outer peripheral surface of 2μ or less (see Japanese Patent Laid-Open No. 57-65837).
.

These piston rings have excellent abrasion resistance in the sliding motion, so there is little wear on the mating cylinder bore, and even under high heat loads, there is no significant decrease in hardness, increase in crankshaft, or deterioration of the coating. It also has the advantage of being superior in terms of anti-seizure properties.

(Problems to be solved by the invention) However, in the above-mentioned piston ring, surface treatment (
Ion plating, etc.) Name of the piston ring body: μ, Nishitetsu, spring steel, tool steel, 13Cr and l7
Since it is Cr stainless steel, the mechanical properties of the material itself and ion plating treatment (heat treatment temperature around 500℃)
The piston ring body has a Pinkers hardness of 1 (V 400 or less), and there is a problem that the purity of the upper and lower surfaces, which is one of the performance characteristics of a piston ring, is insufficient. , 13Cr and 17Cr stainless steels tend to form a passive film, and if care is not taken in the cleaning process before ion plating or OR plating, the film formed on the piston ring body will have poor adhesion.

In addition, the stainless steel mentioned above is treated with gas nitriding.
There are problems such as sufficient adhesion cannot be obtained unless the compound layer formed on the surface is removed by in-machine polishing or chemical polishing, and PVD treatment reduces the fatigue strength of the piston ring body.

In order to solve these problems, the present invention facilitates the process before surface treatment such as ion plating, increases the hardness of the piston ring body, and improves scuff resistance and The purpose is to provide a piston ring with improved wear resistance.

(Means for Solving the Problems) In order to achieve the above objects, the piston ring of the present invention is made by forming a steel wire material whose chemical composition conforms to SKH51 to 54, and heat-treating the material to a hardness of 1-IV600 to 900. The main feature of this piston ring body is that at least the sliding outer circumferential surface of the piston ring body is surface-treated to form a one-needle scuff taste and a coating film that is resistant to rusting.

(Function) By setting the above-mentioned process to A, the ion plating table can be heated to 500°C by the 5ILI process.
One side of the piston ring body against the processing temperature of the tube,! The inner base material of the piston ring maintains a hardness of 1 within a predetermined range in contrast to the hardness of the Vl film on the surface of the piston ring, so the toughness of the piston ring itself is ensured. The piston ring can be installed in the ring groove of the piston without breaking, and the life of the piston ring can be improved by using a coating film that has good adhesion to the piston ring body and has scuff resistance and wear resistance. can.

(Example) Embodiments of the present invention will be described based on the drawings.

Figure 1 shows a partially detailed cross-sectional view of the V-shaped piston 2 in the cylinder bore 1 with the piston 2 spaced apart.

A piston ring 4 is fitted into an algebraic ring groove 3 (one of which is shown in the figure) formed on the outer periphery of the piston 2. 1.1 [port] 5 is applied to cylinder bore 1 4i and 6 with a predetermined soil filling force.

On the outer periphery 5 of the piston ring 4, a broken coating film 5a of 'I'iN is formed by ion plating.

The piston ring body, which is the base material of the piston ring in this example, has a chemical composition of phase family C! :0.8~1.4 inch, W
: 5-7 yen, V: 1.5-. 1.5 chi, +)1 o:
4.5-5.5%, Cr; 3.8-4.5%, p
e: High predicate steel 8K) 151 to 5, which is the composition ratio of the crosspiece
All 4 are adopted. These (1) steel wire rods having a quality are formed to produce (f) a fixed-shaped piston ring body 7.
It is heat treated to a range of 900°C.

The heat treatment conditions for the steel wire rod having the cross-sectional shape shown in Fig. 2 are as follows:
Tempering is performed twice at 550C and air cooling for 90 minutes to obtain a hardness of 1) 1v350.

In addition, in order to lower the hardness, tempering temperature is 630℃Cζ
and cool 6099/1. For example, the hard gHv650 Noviston ring body 7 can be used.

Here, the reason for limiting the material and hardness of the piston ring 4 is to prevent deformation of the piston ring 4 and overall low hardness due to the treatment temperature of 5,000 yen by ILI treatment such as ion plating. child. Waru. In addition, the hardness is too high, causing damage to the cylinder bore 1 and the ring groove 3 of the piston ring 2, which form a VC sliding surface between the piston ring 4 and the piston ring 4. The purpose is to avoid the problem of temples breaking.

In addition, coating failure such as ion plating 95
Even if a is simple, the wear resistance will not be significantly impaired due to the hardness of the internal base material.

After the heat treatment, a coating film 5a of 'l' i N is formed on the sliding outer circumferential surface 8 of the piston ring body 7 by the ion grating method so that the film thickness T is 1 to 15 μm.

In addition, since the surface roughness ILz of the coating depends on the roughness of the base surface before treatment, considering the aggressiveness of the coating rupture 5a against the wall surface 6 of the cylinder bore 1 on the wall surface 6 of the cylinder bore 1, It is desirable that the roughness Rz is 1 μ or less.

Therefore, Rz
After U, 5-0.8μ VC finishing, a coating film of '1' r N is formed at a processing temperature of around 500°C.

A piston ring with non-conventional "L' i N coating" is installed in a 20,000C 4-cycle water-cooled 6-cylinder gasoline engine for a high lead gun IJ 7<pb
3.2 y'/US Ga 7) was used to test the test case under full load for 300 hours.

Table 1 shows the measurement results of the above trial and shows the 15 wear fi and the occurrence of initial scuff when the piston ring is used as a top ring.

Here, n is the sample of this embodiment, and B, C, and D are samples 1. of the conventional example. Compared to '2.3.4, it has a scuff resistance of 9' and a wear resistance that is 2 to 5 times higher.

In addition, wear as an oil ring sight rail''!jt
Although not shown in above-1, the wear on the outer circumferential surface of the ring l
It is recommended that f be +111, which is 10% of the top ring plus 8 degrees and 1 inch.

In this example, the surface treatment by ion plating θ3'C was described, and the coating was removed using a 1 m surface treatment method such as composite plating with Ni-based and Fe-based hard particles dispersed. Thickness′
1゛ is about 100μ, or cylinder bore is limited to cast iron, but cylinder carbon and low carbon iron-chromium alloy thermal spray coating is formed, and the film thickness T is about 100μ. A similar effect is produced (ko11).

(Effects of the Invention) As is clear from the above explanation and the above, by limiting the steel type or chemical composition of the base material of the piston ring of the present invention and setting the hardness in the range of Hv 600 to 900, ion spray The hardness of the piston ring body can be significantly reduced during surface treatments such as ion plating. Since the treatment process before formation is completely easy to manage, it is possible to improve the properties of the coating film with the base material, as well as increase the scuff resistance and scratch resistance, and the service life of the coating film.

[Brief explanation of drawings]

FIG. 1 is a partially detailed sectional view showing a state in which a piston ring according to the invention is mounted on a piston in a cylinder bore, and FIG. 2 is an enlarged sectional view showing a coating film of the piston ring of FIG. 1. 4...Piston ring 5...Outer peripheral surface 5a...Coating film 7...Piston ring body 8...Sliding outer peripheral surface'FjJ 'n Participant: Toyota Motor Corporation (and 1 other person) Figure 1 and Figure 2

Claims (4)

[Claims] (1) A scuff-resistant and abrasion-resistant coating is applied to at least the sliding outer peripheral surface of the piston ring body, which is formed from a steel material whose chemical composition complies with SKH51-54 and is heat-treated to a hardness of Hv600-900. A piston ring characterized by forming. (2) The piston ring according to claim 1, wherein the coating film is a titanium nitride film formed by ion plating, and has a thickness of 1 to 15 μm. (3) The coating film is made of composite plating in which Ni and Fe-based hard particles are dispersed, and the film thickness is 100 mm.
The piston ring according to claim 1, which has a diameter of approximately μ. (4) The piston ring according to claim 1, wherein the coating film is made of a sprayed high-carbon and low-carbon iron-chromium alloy, and has a film thickness of about 100 μm.