JPH0434268A - Spraying piston ring - Google Patents

Abstract

PURPOSE:To improve initial adaptability and to prevent a spraying layer from easily exfoliating and to prevent a cylinder bore from abnormally wearing due to exfoliation of the spraying layer and formation of a sharp edge by providing the spraying layer of upper layer, which is less hard than the spraying layer of lower layer, on the spraying layer of lower layer. CONSTITUTION:Blast treatment is applied to a spherical graphite cast iron-made piston ring material 1 after work of grooving the periphery. Next, WC-Co (WC dust is coated with Co by plating) is sprayed by using a plasma spraying machine, thereafter, a spraying layer 4 of upper layer is finish-polished by using a flame fusion coating machine to spray nylon 11 resin. In the drawing, a number 2 is a shallow recessed groove formed over the full periphery in the peripheral surface of the piston ring base material 1, a number 3 is the spraying layer of lower layer, provided in the total surface in the recessed groove 2, to bear wear resistance and a number 4 is the spraying layer of upper layer, provided on the spraying layer 3 of lower layer, to bear mainly the initial adaptability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal sprayed piston ring suitable for high-load internal combustion engines.

C. Prior Art] In recent years, there has been a remarkable trend toward higher speeds and higher outputs in internal combustion engines, and as a result, the load on piston rings has become higher and higher. Since piston rings for such engines are required to have higher wear resistance, seizure resistance, and corrosion resistance, conventional piston rings coated with hard chrome plating cannot be used.

Conventionally, thermal sprayed piston rings have been used next to hard chrome plated piston rings because of their excellent wear resistance, seizure resistance, and corrosion resistance.

In this thermal sprayed piston ring, when thermal spraying material other than MO is thermally sprayed, for example, when ferrochrome or high chromium cast iron material is thermally sprayed as a wear-resistant layer, it is necessary to Aj- between the material and the surface sprayed layer
It is common to provide a base sprayed layer of Ni-based alloy or the like.

On the other hand, regarding the cross-sectional shape of the sprayed layer, the Fu
ll Face Type (1 is the piston ring base material, 20 is the thermal sprayed layer provided on the outer peripheral surface of the base material) is rarely used because it has the disadvantage of increasing blow pie and is expensive to manufacture, as shown in Figure 2. Channel
el Type is often used. In FIG. 2, 2 is a shallow groove formed on the entire outer circumferential surface of the piston ring base material 1, 10 is a base sprayed layer provided on the entire surface inside the groove 2, and 11 is a base sprayed layer on the base sprayed layer 10. This is a thermal sprayed surface layer. Note that the bonding surface between the base sprayed layer 10 and the surface sprayed layer 11 is a schematic representation of an interlock bond.

[Problem to be solved by the invention]

However, since the surface sprayed layer of conventional thermal sprayed piston rings is made of a material with a high melting point, the surface tends to become porous even with the plasma spraying method.For this reason, combined with its high hardness, the finished surface roughness is 1 μmRz or less. It is more capable than mass production technology.

Due to this relatively rough finished surface roughness and poor initial conformability, conventional thermal sprayed piston rings are operated for a long period of time with a high coefficient of wear between the cylinder bore and the piston ring. A period of large twist deformation in the vertical direction continues for a long time, causing peeling of the sprayed layer.

Furthermore, the two-layer thermal sprayed piston ring has the following disadvantages.

■The 17-Ni alloy of the base sprayed layer has a hardness of about H,200, which is softer than the surface sprayed layer or base material, so it is easily abraded by hard powder of combustion products, and when the base sprayed layer is worn out. A recess 12 (see FIG. 3) is formed there, causing a notch effect and deteriorating the peeling resistance of the sprayed layer.

■As the above-mentioned recesses occur, sharp edges are formed in the green of the hard surface sprayed layer, causing stepped wear near the top dead center of the cylinder bore.

■When stepped wear occurs in the cylinder bore, the twist deformation of the piston ring becomes larger, causing plate-like M4# of the sprayed layer.

In addition, the thickness of the base sprayed layer is approximately 60 pm ± 30 μm, and this cannot be reduced because it is necessary to ensure bonding strength with the base material. It can be said that the thermal sprayed layer is placed on the piston ring, and the structure is hard enough to easily form cracks as the piston ring deforms.

An object of the present invention is to provide a thermal sprayed piston ring suitable for a high-load internal combustion engine that solves the above-mentioned drawbacks.

[Means to solve the problem]

The configuration of the first aspect of the present invention is characterized in that an upper thermal sprayed layer is provided on the lower thermal sprayed layer formed on the outer periphery, and the hardness of the upper thermal sprayed layer is lower than the hardness of the lower thermal sprayed layer.

In the second aspect of the present invention, an upper sprayed layer is provided on the lower sprayed layer formed on the outer periphery, and the hardness of the upper sprayed layer is lower than the hardness of the cylinder bore (the hardness of the lower sprayed layer is lower than the hardness of the cylinder bore). is characterized by a hardness higher than that of the cylinder bore.

The lower thermal sprayed layer preferably has a structure in which fine hard particles are dispersed in a matrix made of Co, Ni-P alloy, C0-P alloy, or co-Ni-P alloy, for example, Co-based WC %Crt 03 %Cr s C
Dispersion of hard particles such as t s T 10 ,
A material in which hard particles such as SiC%S'zNa, BN, etc. are dispersed in a matrix of Ni--P, Co--P%, Co--NiP is preferable (see, for example, Japanese Patent Application No. 2-76234).

[Effect]

In the present invention, since the upper thermal sprayed layer having lower hardness is provided on the lower thermal sprayed layer, the initial conformability is improved compared to the case where only the lower thermal sprayed layer is used.

Therefore, the vertical twist deformation of the piston ring is
As the initial familiarization progresses, it becomes smaller in a relatively short period of time,
PAllll of the sprayed layer is less likely to occur.

Furthermore, since the lower thermal sprayed layer is harder than the upper thermal sprayed layer, it is not preferentially abraded by hard powder of combustion products, and the above-mentioned depressions are not formed. Abnormal wear of the cylinder bore is less likely to occur.

The lower sprayed layer is made of Co, Ni-P alloy, Co-P
Having a structure in which fine hard particles are dispersed in a matrix made of alloy or Co-Ni-P alloy has good bonding strength with the base material and also has good wear resistance.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained.A piston ring material made of spheroidal graphite cast iron is machined with grooves on the outer periphery and then blasted using a 7MC plasma spraying machine manufactured by MF and TCO. The particle size distribution is 10-44. um's WC
- After thermally spraying 17% by weight Co (WC powder coated with Co by plating), using a flame spraying machine (Terodyne System 2000, manufactured by Nippon Utec Co., Ltd.), nylon 11 resin (coated powder, manufactured by Nippon Utec Co., Ltd.) was sprayed. Troop 293
30) was thermally sprayed, and the upper thermally sprayed layer was polished and finished.

Fig. 1 shows a thermally sprayed piston ring of the present invention, where 2 is a shallow groove formed on the entire circumference of the piston ring base material l, and 3 is a lower thermal sprayed layer provided on the entire surface inside the groove 2. 4 is an upper thermal sprayed layer provided on the lower thermal sprayed layer 3, which is mainly responsible for initial conformability.The thickness of the lower thermal sprayed layer 3 is 50 μm 1The hardness is Hv850 The thickness of layer 4 is 15 μm. The adhesion strength between the lower thermal sprayed layer 3 and the base material l of this thermal sprayed piston ring is 68M.
5Aj-, which has been used as a base thermal spray layer in Pa,
The adhesion strength of 95N+ is equivalent to 68 MPa, and the adhesion to the base material is good.

The base thermal spray layer thickness of conventional thermal spray piston ring is 50μm,
Compared to the surface sprayed layer thickness of 100 μm and a total of 150 μm, the lower sprayed layer in this example has a thickness of 50 μm and the upper sprayed layer has a thickness of 15 μm, totaling 65 μm, and the sprayed thickness is 1/2 Reduced to below. This increases productivity and also improves the peeling resistance of the sprayed layer.

In the above example, nylon 1 was used as the upper thermal spray layer.
1 resin was used, but the upper thermal spray layer is not limited to this, and may also include, for example, copper-Ninkel alloy, graphite powder coated with nickel, or a mixture of silicon-aluminum alloy and polyester. The upper sprayed layer must be at least 5 μm in thickness to close the surface roughness, pores, etc. of the lower sprayed layer and make it smooth. . However, if the initial run-in allowance exceeds 30 μm, it is undesirable because the amount of initial wear increases.
The thickness of the upper sprayed layer is preferably 5 to 30 μm, and
The thickness of the lower sprayed layer is 50. um is sufficient. As mentioned above, in the tS spraying method, due to the melting point of the sprayed material, a high-power spraying method such as plasma spraying is used for the lower sprayed layer, but a low-temperature spraying method can be used for the upper sprayed layer. .

〔Effect of the invention〕

As explained above, according to the present invention, since the upper sprayed layer with lower hardness is provided on the lower sprayed layer, the initial conformability is improved and peeling of the sprayed layer is prevented. (stomach.

Furthermore, since the lower sprayed layer is harder than the upper sprayed layer, no recesses are formed, and abnormal wear of the cylinder bore due to peeling of the sprayed layer or formation of sharp edges is less likely to occur.

Then, the lower sprayed layer is made of C01Ni-P alloy, Co-P
If it has a structure in which fine hard particles are dispersed in a matrix made of alloy or Co-Ni-P alloy, it will have good adhesion to the base material and also have good wear resistance.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, and is a sectional view showing a part of a thermally sprayed piston ring, Fig. 2 is a sectional view showing a part of a conventional thermally sprayed piston ring, and Fig. 3 shows a worn conventional thermally sprayed piston ring. A cross-sectional view showing a part of the Fu
FIG. 2 is a sectional view showing a portion of a thermal sprayed piston ring of ll Face Type. 1 is the piston ring base material, 2 is the groove, 3 is the lower sprayed layer, and 4 is the upper sprayed layer. Patent applicant Teikoku Piston Ring Co., Ltd. Agent
Patent Attorney Ken OkabeFigure 3Figure 4

Claims (3)

[Claims] (1) A thermal sprayed piston ring characterized in that an upper thermal sprayed layer is provided on the lower thermal sprayed layer formed on the outer periphery, and the hardness of the upper thermal sprayed layer is lower than the hardness of the lower thermal sprayed layer. (2) An upper sprayed layer is provided on the lower sprayed layer formed on the outer periphery, and the hardness of the upper sprayed layer is lower than that of the cylinder bore, and the hardness of the lower sprayed layer is higher than that of the cylinder bore. A thermal sprayed piston ring characterized by: (3) A claim characterized in that the lower sprayed layer has a structure in which fine hard particles are dispersed in a matrix made of Co, Ni-P alloy, Co-P alloy, or Co-Ni-P alloy. The sprayed piston ring according to 1 or 2.