JPS5932654B2 - piston ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a piston ring for internal combustion engines with wear resistance,
This invention relates to surface treatment technology for sliding surfaces that require seizure resistance.

In recent years, internal combustion engines have seen a trend towards higher rotation speeds and higher compression in order to improve performance, as well as an increase in heat load to combat exhaust gas, which puts strain on the sliding parts of the piston, piston ring, and cylinder liner. It is becoming.

Particularly in diesel engines, carbon suits occur, and for high-speed rotation, the wear resistance between the piston ring and cylinder liner, seizure resistance, wear resistance between the piston ring and piston, seizure resistance, ζ anti-scuffing, etc. Gender becomes an issue. Conventionally, as a countermeasure against this problem, Cr plating or M
o The upper and lower surfaces in contact with the piston are coated with Cr plating and/or shaped, and the piston side, where the piston ring is attached, is fitted with a wear-resistant ring.

Cr-plated piston rings (hereinafter referred to as Cr-plated ring rollers) do not have good seizure resistance with the mating cylinder liner cast iron material, so ordinary cast iron is prone to seizure and scuffing.

For this reason, cast iron cylinder rattoners to which Ni, Cr, Mo, B, and Nb are added are used, but the workability is poorer than that of conventional cast iron, and the cost is also high. Mo
Thermal sprayed piston rings (hereinafter referred to as Mo thermal sprayed rings) have good seizure resistance with the mating cylinder liner cast iron material, but in engines that are subjected to heat loads of 300 to 350°C or higher, the oxidation of Mo causes the base material piston to Adhesion between the ring and the sprayed layer becomes a problem, and the Mo material cost is extremely high, resulting in a high-cost piston ring. In addition, recently mixed thermal spraying of Fe-based + Mo-based or Fe-based + ceramic-based systems has been seen, but Mo-based systems are expensive, and there are few engines that require such high scuffing resistance.
Mixed thermal spraying of ceramic type and ceramic type leaves problems with workability, adhesion, and a decrease in hardness at high temperatures.

Mixed thermal spraying of Fe type and Mo type can be expected to have a certain degree of adhesion, scuffing resistance, wear resistance, etc., but the cost is higher than that of the piston ring of the present invention. Also, since it uses Mo, it has excellent scuffing resistance, but
Essentially, oxidation of Mo during high-temperature use poses a problem. The present invention eliminates the drawbacks of the prior art and not only has excellent wear resistance and seizure resistance of the piston ring itself, but also improves the wear resistance and seizure resistance of the cylinder liner cast iron, which is the mating material. The present invention provides a low-cost piston ring that is of good quality and is cheaper than a Mo sprayed ring and comparable to a Cr-plated ring.

The gist of the present invention is 55-70(f)C-7
Fe-C-C consisting of 0%Cr-3~9%C and balance Fe
The r-alloy star/ping powder is made into a rounded powder with a particle size of 44μ (350 meshes) to 10μ, and then the powder is sprayed onto at least a part of the sliding surface of the piston ring by plasma spraying. It is located in the piston ring.

In the Fe-C-Cr alloy of the present invention, the amount of C is 3 to 91
: fl) was chosen because if the C% is less than 3q1), the stamping ability will be poor and the powder cost will be high, and if the C% is too high, the adhesion and thermal spray workability will be poor, so the upper limit was set at 9%. And so.

Also, Cr% is 55~55 from the viewpoint of powder cost and wear resistance.
It was set to 70% Cr. Note that Si, Mn, P, S, etc. may be used in amounts that are generally present in carbon steel.
Further, if the powder particle size is coarser than 44μ, the porosity becomes large, resulting in poor wear resistance and scuffing resistance, and if the powder particle size is too fine than 10μ, the thermal spraying efficiency is extremely poor. For this reason, the particle size of the thermal spray powder was set to 44μ to 10μ. Furthermore, among the above particle size ranges, 50% of the total particles are in the particle size range of 37μ to 20μ.
The above conditions bring about more favorable results.

In the present invention, stamping powder is used. In the case of atomized powder, the particle size varies widely, and the yield of thermal spray powder in the particle size range of 44μ to 10μ used in the present invention is 20μ
Since it is low at ~40% and expensive, it is not suitable for practical use. In the present invention, the powder particles were rounded using a dinit mill or a pole mill.
In the piston ring according to the present invention, the thermal spray powder produced as described above is applied to the ring groove 2 of a cast iron or steel piston ring 1 as shown in FIG.
It can be obtained by plasma spraying to a thickness of 5 mm and grinding to a finished thickness of 0.1 to 0.25 mm.

In addition, the surface-treated piston rig of the present invention is particularly suitable for high loads,
It exhibits excellent characteristics as a low-cost piston ring for high-speed rotating diesel engines, but it can also be satisfactorily used as a piston ring for internal combustion engines such as gasoline engines.

Example 1 Spherical graphite piston ring base material (shape nominal diameter =
90φ, T size = 3.8U77! , After machining the outer circumferential surface and upper and lower surfaces of dimension B = 2.5 m0, grooves were made on the outer circumferential surface as shown in Figure 1 and 2 (groove depth 0.2 m0, and after degreasing, cleaning, and drying,
Plasty/glued with calcined alumina.

It is then sieved to reduce the particle size to 350 mesh (4
4μ) A finer powder consisting of 63% Cr-8.2% remaining Fe is 0.3 to 0.3 μm by plasma spraying.
5 coated. After coating, the piston ring is finished to the specified dimensions by grinding with a grinder, and in order to check the adhesion between the base metal and the sprayed layer, the piston ring is put on a tensile tester and pulled until it peels off. did. After further finishing, 350'CX
The sample was kept in an oxidizing atmosphere for 30 hours, and after being slowly cooled, it was similarly applied to a tensile tester to determine the adhesion strength. The Fe-C-Cr alloy powder of 63% Cr-8.2% C-balance Fe used in this case was crushed by stamping, then passed through a supersonic dinit mill and heated at an air pressure of 5.5 mm/cm. (
177!2, inflowing air with a flow rate of 3Nm''/Min,
It is struck from a nozzle against a collision plate at high speed to give it a rounded shape as shown in Figure 3.

Similarly, MO thermal sprayed rings used as conventional thermal sprayed piston rings, 65 to 90% MO-10 to 35 (F6Ni alloy thermal sprayed piston rings found in literature, etc.) are also used at room temperature and 350% to obtain adhesion. ℃×
The specimen was kept in an oxidizing atmosphere for 300 hours, and after slow cooling, a tensile test was conducted. The sprayed piston ring of the present invention has a temperature of 23% at room temperature.
0-26.0mm 1350℃ x 3OO hours is 24
．． There was almost no difference between 5 and 26.0 mm. M
O-Ni alloy sprayed piston ring is 22.5~2 at room temperature.
6.0m” 350℃ x 300 hours is 17.9~
19.9 mm, while the MO sprayed piston ring showed a relatively high value of 19.0 to 22.5 mm at room temperature, but the value of 12.1 to 1
It showed an extremely low value of 4.4 mm. In addition, the limit of adhesion strength is 15 to 17 mm f) MO by a tensile test.
Diesel engine (2.2e) VC installed with thermal spraying ring, 1000r. p. m no load~4400r, p. m1
A deep down bench test with repeated full loads for 300 times.
When I observed the piston ring after disassembling it for a while, I found that
Since peeling of the sprayed layer was observed, it seems that a tensile test value of 17 degrees or more is required.

Example 2 The star/ping powder of 63% Cr-8.2% C with balance Fe of Example 1 was not subjected to dinit milling, but the powder particle size of 74μ (200 mesh) to 5μ was used to produce plasma in the same manner as in Example 1. I did thermal spraying.

As seen in FIG. 2, the shape of the powder varied, and the thermal spraying efficiency and thermal spraying yield decreased to 2/3 to 1/2. Furthermore, as shown in FIG. 5, the number of pores on the surface of the sprayed layer (FIG. 4) is larger than that of the layer pulverized by a dinit mill. Thermal spraying efficiency here means the coating thickness per unit time when spraying is carried out under the same conditions, and the thermal spraying yield is the amount of powder attached to the object to be sprayed and the amount of powder consumed when spraying is carried out for a certain period of time. means the percentage of

Example 3 0.7%C-0.4 with low powder cost
8%Si-0.47%Mn-13.0%Cr-balance Fe
(7) After spraying Fe-Cr alloy onto piston rings by plasma spraying and finishing by grinding, MO
Sprayed ring, together with the piston ring of the present invention VC4 (1)
After being kept in a furnace at °C (10-2 mmHg vacuum furnace) for 5 hours,
It was taken out and the tension was measured.

This result shows that the MO sprayed ring and the piston ring of this invention showed almost no change in tension compared to new ones, whereas the Fe-based 13% Cr steel powder showed a decrease in tension of 1.
．． The weight was found to be 5 to 2.5 kg. Example 4 The amount of wear of each piston ring and cylinder liner was measured when a Cr metal ring, an MO sprayed ring, and a piston ring according to the present invention were used.

In the test, these piston rings were installed in a 2200cc engine and the engine was operated at 4400r. pm for 100 hours under full load. The results are shown in FIG. In Fig. 6, the upper part shows the wear amount of the piston ring, and the lower part shows the wear amount of the cylinder liner. Indicates the amount of wear on piston rings and cylinder liners. Example 1 VC as seen 5
Piston rings thermally sprayed with a Fe-C-Cr alloy of 5-70Cr-3-9C and the balance Fe exhibit sufficient oxidation resistance even in an oxidizing atmosphere at 350°C. , MOO3 oxides were present, which significantly reduced the adhesion to the base material cast iron or steel. Also MOichiNi
Even after conducting an oxidation test at 350°C for 300 hours, the adhesion of the alloy mixed sprayed piston ring is 17 to 20 mm.
The scuffing resistance and seizure resistance are also the same as those of MO sprayed rings, but there is almost no difference in cost compared to MO sprayed rings, and the hardness is also higher than that of MO sprayed rings.
70Cr-3-9C-balance Fe sprayed layer Hv7OO~9
00 (Vickers hardness), which was lower at Hv6OO~850 than Hv850~1050, and its own wear amount was about twice that of the piston ring according to the present invention. On the other hand, the 55-70Cr-3-9C-balance-Fe piston ring of the present invention has inferior scuffing resistance and seizure resistance compared to the MO sprayed ring, but the amount of wear on the mating member and the amount of wear on itself is also small. , excellent abrasion resistance, and good adhesion under high temperature loads. Compared to Cr metal ring, the seizure resistance and scuffing resistance are lower than that of Cr due to the presence of pores in the sprayed layer.
It is superior to Metsuki ring, and its wear resistance is almost the same as Cr Metsuki ring. 55-70% Cr-3-9%
Powder of C and balance Fe is used as a ferroalloy when alloying cast iron and steel, and is easily available commercially, but the commercially available powder is manufactured by stamping and has a particle size of 74μ to 5μ. It shows a wide distribution, and if used as is, the sprayed layer will have many pores, and the spraying yield and efficiency will be poor. Therefore, after sifting it into an appropriate particle size range, it is introduced into a supersonic air stream and struck against a collision plate at high speed. It is necessary to give the powder particles a roundness by a method or by using a ball mill or the like.

If the stamping powder is used as it is, even if the powder particle size is within the same range as that of the present invention, when thermal spraying is carried out under the same thermal spraying conditions as the present invention, the thickness of the sprayed amount will be 43 to 55μ. Compared to the hot one, the one that was rounded by the dinit mill had a thickness of 79 to 95μ, about twice as thick, and showed excellent thermal spraying efficiency. Changes in the fluidity of thermal spray powder during mass production increase the variation in thickness, which requires a correspondingly large processing allowance, leading to increased costs. Fe-Cr alloys with low Cr content of 13% have hardness of Hv6l3~
813, which is 150 to 250 lower than the ring of the present invention, and it also has problems such as the possibility that the tension will decrease when used under high loads. The piston ring according to the present invention has a high load edge y1 which is a problem with conventional Cr plating 117g.
For example, it is particularly effective in high-speed diesel engines, and the low-cost piston ring of the present invention can be used satisfactorily without using a high-cost MO sprayed ring.

The piston Y ring according to the present invention has the following effects.

(1) Lower cost than conventional thermal spray rigs.

(2) The scuffing resistance is superior to that of the -Cr metal ring. (3) Wear resistance is superior to MO sprayed rings and equal to or better than Cr metal rings.

(4) Adhesion is superior to MO sprayed rings, and is particularly excellent as a piston ring for high-speed, high-load diesel engines.

(5) There is no decrease in adhesion, hardness, or tension due to high temperature use.

(6) The powder used is widely commercially available and easy to obtain.

[Brief explanation of the drawing]

Figure 1 is a partial sectional view of the piston and piston ring;
Figure 2 is a photograph showing the shape of stamping powder (X5OO)
, Figure 3 is a photograph (x500) showing the shape of the stamping powder after it has been applied to a dinit mill, and Figure 4 is a photograph (X
Figure 5 is a photograph (X
Fig. 6 shows the amount of wear of each of the three types of thermal sprayed rings, Cr metal rings, and piston rings according to the present invention, and the amount of wear of the cylinder liner, which is the mating member. This is a graph showing. 1... Piston ring, 2... Sprayed layer, 3... Piston, 4... Cylinder liner, A... Amount of wear when using MO sprayed ring, B... Using Cr metal ring Amount of wear when using the piston ring according to the present invention, C... Amount of wear when using the piston ring according to the present invention.

Claims (1)

[Claims] 1 Stamping powder of Fe-C-Cr alloy consisting of 55 to 70% Cr, 3 to 9% C, and balance Fe was stamped with a particle size of 44μ.
A piston ring characterized in that the powder is formed into a rounded powder with a diameter of ~10μ and then sprayed on at least a part of the sliding surface of the piston ring by plasma spraying.