KR860001967B1 - Method sintering of oxidation of piston ring - Google Patents

Abstract

The method is for forming one or several grooves on the outer face of the piston ring, next pressing the doughy mixtures of 100 wt.% blends, which consist of 97 wt.% Fe3O4 particles under 100 micron size and 3 wt.% graphite powder, and 20-25 wt.% sodium silicate as a binder into grooves of the piston ring, and finally sintering the piston ring at 300-350≰C for 60 minutes.

Description

Iron oxide sintering method of piston ring

1 is a perspective view of a piston ring made in accordance with the present invention.

2 is an enlarged sectional view taken along the line A-A of FIG.

The present invention relates to a method for sintering iron oxide in a piston ring. In particular, the present invention relates to a piston ring iron oxide sintering method which is rich in retention property and excellent in self-lubrication property that can exert an excellent effect on welding and wear resistance in a high load engine under severe operating conditions.

In recent years, due to the remarkable development of various industries, the expansion of various means of transportation such as automobiles, railways, ships and airplanes, and industrial machinery for agricultural and construction has been rapidly promoted. This necessitated high load operation.

However, the high load operation causes partial melting of the cylinder inner wall due to severe friction between the piston ring and the cylinder inner wall, which plays a role in adjusting the lubricating oil in the cylinder during suction and compression stroke of the cylinder. In addition, accelerated partial wear of the cylinder inner wall shortens the engine life and, in some cases, renders the engine impossible, causing various accidents.

)특성을 갖는 사삼산화철 Fe₃O₄와 흑연을 압입소결하여 피스톤링의 윤활조건을 개선함으로서 고부하 운전 조건에서도 장기간 견딜 수 있는 피스톤링을 제조하려는 시도가 수없이 행하여졌다. 그러나 이같은 산화철 소결방법에 의해 피스톤링을 실제 제작하는 경우에, (1)소결시의 압입 산화철 수축에 따른 결합 불량, (2)사용윤활유에 의한 산화철 용해 유출현상 및 (3)고부하운전시 산화철 소결체의 압입홈 이탈현상등의 발생으로 오히려 실린더 내벽의 보유성 및 윤활성 등이 불량해지고 엔진성능 및 내구성에 악영향을 미치는등 부작용이 수없이 발생함으로서 이 방법 또한 만족할만한 효과를 얻지 못하고 있었다.As a way to solve this problem, a method of reducing the wear of the cylinder wall caused by high load operation is known by applying hard chromium to the outer peripheral surface of the piston ring, but even when using such a hard chrome plated piston ring If the high-load operation condition is prolonged for a long time, the occurrence of fusion wear or abnormal abrasion cannot be avoided, which is not a satisfactory solution. As a way to alleviate the disadvantages of such hard chromium-plated piston rings, one or more grooves may also be provided along the outer circumference of the piston ring, which itself is a solid lubricant and welder.

Many attempts have been made to produce piston rings that can withstand long periods of time under high load operating conditions by press-sintering and sintering iron trioxide Fe ₃ O ₄ and graphite. However, when the piston ring is actually manufactured by the iron oxide sintering method, (1) poor coupling due to shrinkage of the press-fitted iron oxide during sintering, (2) leakage of iron oxide dissolution by lubricating oil, and (3) iron oxide sintered body during high load operation. This method also failed to obtain a satisfactory effect because of the numerous side effects such as poor retention and lubrication of the inner wall of the cylinder and adversely affecting engine performance and durability.

As a result of numerous studies to solve the above problems, the present inventors have selected the optimal state of the iron oxide blending method and the heat treatment method, so that the iron oxide is indented in the high load operating conditions with excellent iron oxide hardness, bonding strength and filling degree. The iron oxide ring can be manufactured that does not dislodge at all and does not dissolve in lubricating oil and can sustain excellent effect of welding and wear resistance.

More specifically, the present invention, as shown in FIG. 2, forms one or several grooves on the outer circumferential surface of the piston ring, and the iron trioxide (Fe ₃ O ₄ ) and graphite (97) having a particle size of 100 microns or less. : 3) The initial contact state between the piston ring and the inner wall of the cylinder is improved by injecting 100 parts by weight and 20 to 25% by weight of a sodium silicate dough into a sintering furnace at 300 to 350 ° C. for 60 minutes. It is possible to provide a method of sintering the iron oxide of the piston ring which can increase the wear resistance by improving the prevention of scuffing and lubricity.

In general, the role of the piston ring in the cylinder includes (1) hermetic action, (2) heat transfer action, and (3) lubricating oil adjustment action. The purpose is to promote.

In other words, the present invention maintains the strength of cast iron, which is the material of the piston ring, while producing and retaining excellent retention of the oil width getter derived from the porous structure of the fine iron oxide powder sintered body. It is. The main purpose of the lubricating oil is to supply lubricating oil to the inner wall of the cylinder once it is kept in the sintered body space, thereby improving the lubrication conditions and preventing the lubrication of the lubricating oil film.

In the present invention, the use of the iron oxide and graphite (97 + 3) mixture is intended to use graphite as a solid lubricant, but when the content exceeds 3% by weight, the bond strength and hardness of the piston ring and the sintered iron oxide are reduced. It cannot be used as a piston ring.

At this time, iron trioxide and graphite use materials having a particle size of 100 microns or less, because when these particles have a particle size of 100 microns or more, the density of iron oxide in the packing decreases, and thus the required hardness cannot be obtained.

As the binder, sodium silicate is used, and the binder content is preferably 20 to 25 parts by weight based on 100 parts by weight of the iron oxide / graphite (97 + 3) mixture. If the amount of the binder is 20 parts by weight or less, the bond strength and hardness decreases due to the lack of the binding force between the iron oxide particles. If the amount of the binder is 25 parts by weight or more, the bond strength and hardness between the iron oxide particles are increased, but the filling degree of iron oxide is increased. Is lowered.

In addition, the temperature of the heat treatment furnace can be used at 200 to 400 ℃, 300 to 350 ℃ is preferred. If the heat treatment temperature is 200 ° C. or lower, the bond strength and hardness are lowered due to the lack of coking force of sodium silicate. If the heat treatment temperature is 400 ° C. or higher, the bond film itself is cracked, and the bond strength and hardness are also decreased. . Moreover, when 700 degreeC or more, the hardness of a ring material (cast iron) falls and is unsuitable. When the heat treatment time is 1 hour or more, a softener or an excellent product can be obtained. However, the heat treatment time is 60 minutes in consideration of energy saving effects.

The invention is readily apparent from the illustration of Figures 1 and 2.

1 is an overall perspective view of a piston ring manufactured according to the present invention, which is composed of a ring body 1, an iron oxide sintered body 2, and a ring free space 3.

2 is an enlarged cross-sectional view taken along the line A-A of FIG.

The invention can be explained in more detail from the following examples.

Example 1

Combination Ratio Test of Iron Oxide and Binder

As shown in FIG. 2, 0.5 mm (width) x 2 mm (depth) groove processing is performed along the outer peripheral surface of the piston ring, and the mixing ratio of the iron oxide and graphite (97 + 3) mixture and the binder (B: sodium silicate) is shown. After filling the groove with the dough-like material prepared by changing as shown in Table 1 and sintered for 1 hour in the sintering furnace of about 315 ℃ temperature, the bond strength, hardness and filling test was conducted according to the following method, The results are listed in Table 1. Conventional blends (iron oxide 97 + graphite 3 + sodium silicate 3) were used as control experiments.

A) Bond strength test

The finished piston ring was hung on the universal testing machine to break the free space (3) with a force of about 45 kg / mm 2, and then the length of the groove in which the filling was peeled to the bottom was measured with a vernier caliper. The length of the peeled groove was less than 10 mm as a pass product.

B) hardness test

The width of the scratched magnetic pole generated by moving the diamond particles to the piston ring groove surface 2 filled with the filler by applying a load of 100 g to the Vickers hardness tester was measured using a metal microscope and a photographing apparatus.

The width | variety of the scratched magnetic pole was less than 0.2 mm as a pass product.

C) Filling test

The completed piston ring was visually inspected. Less than one unfilled part whose length of the part not filled up to the ring groove bottom was 1 mm or less was made into the pass product.

TABLE 1

In Table 1, A: B is the weight ratio of the iron oxide, graphite (97 + 3) mixture and the binder (sodium silicate), and D / C is the number of pass test pieces / use test pieces.

From the test it can be easily seen that the use ratio of the binder 20 to 25% by weight is optimal. In addition, it was found that the hardness and filling degree were very excellent in the control experiment.

Example 2

Heat treatment temperature test

The ratio of the iron oxide / graphite (97 + 3) mixture and the binder was 100: 20, and the piston ring was manufactured in the same manner as in Example 1 except that the sintering temperature was changed as shown in Table 2. And the filling test was performed, the test results are listed in Table 2.

TABLE 2

From Table 2 it can be easily seen that the heat treatment temperature is suitable for 300 to 350 ℃.

Note: If the heat treatment temperature is 700 ℃ or higher, the hardness of the ring material (cast iron) decreases and is not suitable.

Example 3

Heat treatment time test

The ratio of the iron oxide / graphite (97 + 3) mixture and the binder was 100: 20, and the piston was prepared in the same manner as in Example 1 except that the sintering temperature was fixed at 300 ° C. and the sintering time was changed as shown in Table 3. Rings were prepared and tested for bond strength and hardness. Test results are listed in Table 3 below.

TABLE 3

As a result of measuring the wear amount on the outer circumferential surface of the ring, the wear amount of the present invention was only 1/2 as compared to the conventional piston ring.

Claims (1)

One or several grooves are formed on the outer circumferential surface of the pisdeling, and in this groove, tetrahexan oxide having a particle size of 100 microns or less, (Fe ₃ O ₄ ) and 100 parts by weight of a mixture of graphite (97: 3) and a binder (sodium silicate) 20 to 20 A method of sintering iron oxides in a piston ring, characterized in that 25 parts by weight of mixed dough material is pressed in and then sintered in a sintering furnace at a temperature of 300 to 350 ° C. for 60 minutes.

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