JPS58133454A - Cylinder whose inner circumference is treated by hardening - Google Patents

Abstract

PURPOSE:To prevent wear, etc. at the stage near the boundaryof a hardened layer and a cylinder mother metal in such a way that the hardened layer which is gradually shallowed in the axial direction toward the skirt side is formed, in the pressure ring sliding range around the inner circumference of the cylinder. CONSTITUTION:In a cylinder, depth of quenched layer is grandually shallowed toward the skirt side and laser quenching is spirally performed in such a way that a quenched layer width (A) is secured approximately 50mm. in the axial direction from near the top dead point of a top ring to the skirt side, a quenched layer width E is secured to approximately 2.5mm. at the pitch of approximately 5mm., and a quenched layer depth H is secured to approximately 0.3mm. near the top dead point of the top ring. In consequence, the boundary by the hardened layer and the cylinder mother metal can be prevented from being subjected to the local wear in such a way that its positions are grandually transferred owing to the wear.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder having a hardened layer on its inner circumferential surface, particularly a cylinder used in an internal combustion engine, etc., a cylinder inner circumferential surface, and a cylinder sleeve (hereinafter simply referred to as a cylinder). It is.

As shown in FIG. 1, a worn cylinder is generally found to have more wear between the top ring's top dead center and the second ring's top dead center. The main reason for this wear is that the area near the top dead center of the top ring is close to the combustion chamber and is exposed to high temperatures, making it easy for lubricating oil to run out and deforming the cylinder.Also, the back pressure on the piston ring is high due to explosion pressure. This is because microscopic scuffing phenomenon is more likely to occur. Therefore, in order to extend the life of the cylinder, it is especially important to take measures against wear near the top dead center of the top ring.

Conventional methods to prevent this wear include sub hardening, induction hardening, carburizing,
There are methods such as nitriding, and methods of applying wear-resistant coatings such as chrome plating and thermal spraying, and there are many conventional methods such as applying these methods only to the inner circumferential surface of the cylinder or to areas that are subject to a lot of wear. . Among these, as shown in Fig. 2, the top ring 2 installed in the ring groove of the piston 1 has been hardened, chrome plated, or thermally sprayed near the sliding area in consideration of economical aspects. The hardness difference between these hardened layers 5 and the cylinder base material 4 is large, causing stepped wear 5 near the boundary between the two, which can lead to wear on the upper and lower surfaces of the piston ring, blow pie, or breakage of the piston ring, which can lead to serious engine trouble. induce.

The present invention solves the above-mentioned drawbacks by providing a hardened layer within the pressure ring sliding area on the inner peripheral surface of the cylinder, and making the depth of the hardened layer gradually shallower in the axial direction toward the skirt side. In addition to imparting wear resistance and scuffing resistance to the cylinder, the hardening layer is installed one foot deep only in areas of severe wear near the boundary between the cylinder base material and the hardened layer, unlike conventional methods. As a result of placing all emphasis on wear resistance and relying only on improving hardness, differences in mechanical properties due to material differences between the cylinder base material and the hardened layer are ignored, especially on sliding surfaces that undergo reciprocating motion. Since the material strength of the surface layer has a large influence on wear resistance, stepped wear occurs near the boundary between the cylinder base material and the hardened layer.

Therefore, in the case of the present invention, in order to avoid sudden changes in material properties at the boundary between the hardened layer and the cylinder base material, the depth of the hardened layer is made gradually shallower toward the cylinder base material. The material is close to that of .

Furthermore, since the depth of the hardened layer is shallow at the boundary with the cylinder base material, the hardened layer is gradually worn away as the inner circumference of the cylinder wears out, so the boundary position moves from the skirt side to the top ring top dead center. gradually move to the side. Therefore, in a conventional cylinder in which a hardened layer of local VC is provided with a constant depth, the boundary with the cylinder base material is at a constant position in the axial direction, so stepped wear is likely to occur at that part. If the boundary between the hardened layer and the cylinder base metal shifts its position sequentially due to wear, it is possible to prevent local wear. .

A laser beam is used as the heating source. This beam has good focusing properties such as #1, which can heat only the irradiated area, and can easily harden cast iron.It has a high energy density, and it is easy to control the treatment area, width, depth, etc., and it can be used in the atmosphere. This is because it has the advantage that it can be treated with Since there is a lot of wear, a midline of the hardened layer of 10 to 50 cm is appropriate.

The maximum depth of the hardened layer is 0.1 to 0 based on normal wear conditions.
．． Five items are appropriate. If it is less than 0.1, the desired hardness cannot be obtained and the wear resistance may be insufficient.
If it exceeds 5gl11, it is economically inferior.

If the hardened layer is laser hardened, there will be a remarkable effect on wear resistance and scuffing resistance Kli+, and partial hardening is possible, making it easy to control the hardening depth, hardening, etc.

Further, if the hardened layer has a crystalline structure of graphite precipitation, it has a remarkable effect on scuffing resistance and wear resistance under severe friction conditions.

Furthermore, if the hardened layer has a chilled structure and a quenched structure, in addition to the scuffing resistance and wear resistance of the chilled structure, the quenched structure with self-lubricating graphite can withstand even harsher conditions. It has a remarkable effect on scuffing resistance and wear resistance under friction conditions, and by changing the prefocus distance of the laser beam, it is easy to change from a chilled structure to a hardened structure. It is appropriate to create a chilled structure with no graphite precipitation for 5 to 20 m from the top dead center of the top ring toward the skirt side, and to laser harden the 5 to 30 mm following the chilled layer.

Further, it is preferable to provide the hardened layer line spirals, horizontal stripes, vertical stripes, intersecting lines, etc. at intervals. In that case, the area ratio of the hardened layer to the inner peripheral surface of the cylinder in the area where the hardened layer is provided is 4.
A value of 0 to 100X is appropriate. 40. This is because if it is less than %', wear resistance and durability will be insufficient.

Next, an example will be described.

[Example 1] 7, 03.10! X, Bi2.15! X%Mn0.7
5! X, Po, 20%', Oro, 31 N, remainder? The following four types of cylinders were fabricated using a carbon dioxide laser device on the inner circumferential surface of a cylinder made of flaky graphite cast iron having an angle of θ.

As shown in Fig. 3, the cylinder
50■, pitch P 5■, hardened layer K k 2.5 cod, hardened layer depth HYr 0.5m near the top dead center of the top ring, and gradually reduce the hardened layer depth toward the skirt side. The laser hardening irradiation conditions are output 1.0EI and irradiation speed 1.
1I/,, prefocus toward the skirt side 6
Gradually increase the depth from 0 to 8o■, and gradually reduce the depth of the hardened layer.

The cylinder Y is made of the above-mentioned material and has an axial width of 10cm from the top ring top dead center to the skirt side, and a pitch P.
(5-, chill width F 2.5■, chill layer depth Ht) 0.3■ near the top dead center of the tube, and gradually reduce the chill layer depth toward the skirt side in a spiral shape. Laser chill T-applied, axial width following the chill layer is 60cm, pitch P is 5m,
The hardened layer E was set to 2.5 cm, and the depth of the hardened layer was gradually decreased toward the skirt side, and laser hardening was performed in a spiral manner.

The irradiation conditions were an output of 1.0EN and an irradiation speed of 6oo to 1oo.

-1. Pre-focus [gradually increased from 3o to 8o- to allow chill layer and hardened layer to coexist.

Cylinder V and cylinder zB were tested as comparatively soft materials.

The cylinder V is made of the above-mentioned material, with an axial internal force A of 50 mm from the top ring top dead center toward the skirt side, and a pitch P'.
IH2.5 cod, quenched layer K 2.5 snow, quenched layer depth Hf
A cylinder with a constant depth Hi was produced by hardening the entire surface in a medium A in the axial direction at O65m.

Cylinder ZJff, an untreated cylinder made of the above-mentioned material was produced.

The above four types of cylinders have an inner diameter of 116, water-cooled 6 cylinders,
A 7,860 cc, 185 horsepower diesel engine was installed with six cylinders each, and the engine was tested twice under full load for 400 hours. The dog ring is hard chrome plated.

Figure 4 shows the average wear amount and stepped wear amount measured at eight locations on the top dead center of the top ring of the cylinder after the test. The wear is approximately 1/3 of that of untreated material 2, and there is no stepped wear at the boundary between the cylinder base material and the laser-hardened layer, unlike in cylinder V, which is laser hardened to a constant depth, resulting in extremely excellent wear. The characteristics were shown.

Also, cylinder 2 has numerous visible scratches all over its surface.
Compared to the above, the sliding surfaces of cylinder X and cylinder Y have very clean surfaces with no visible sliding scratches. Prove.

[Example 2] T, 05.25%, 812.10%, MnO, 70%
, PD, 32%, 80, 04%, Oro, 26%
, remaining? A carbon dioxide laser device W is used on the inner peripheral surface of a cylinder made of flaky graphite cast iron with an output of 1.0■ and an irradiation speed of 600.
``/=, The prefocus was gradually increased toward the skirt side with a prefocus of 60 to 50 mm, and the depth of the chill layer was made shallower.The depth of the chill layer was 50 m, the pitch P was 5 m, and the chill width E was 2. Cod, Chill Layer Depth Ht) Cylinder W was made by laser chilling in a spiral manner by setting the chill layer depth to 0.5 m near the top dead center of cod, and gradually decreasing the depth of the chill layer toward the skirt side.

'□ Cylinder W has an inner diameter of φ91.1, water-cooled 4 cylinders, 2!
Two cylinders were installed in a 100 cc, 95 horsepower diesel engine, and two untreated cylinders 2' made of flake graphite cast iron with the chemical composition mentioned above were installed as comparison materials. A full load 200 hour durability test was carried out.

The top ring is plated with hard chrome.

After the test, there was no stepped wear on the cylinder W at the boundary between the cylinder base material and the laser-hardened layer, and it is clear from the average wear amount measured at eight locations at the top dead center of the top ring as shown in Figure 5. As can be seen, the wear characteristics of the cylinder W according to the present invention are very excellent, and there are no visible sliding scratches in the sliding movement, and the surface is very clean, so it has good scuffing resistance. Turns out to be excellent.

The scuffing limit load tests conducted on laser-hardened and laser-chilled materials will be described below.

As shown in Figure 6, length 70cm, medium 17m, thickness %, M
nO, 81X, Po, 25%, Oro, 28N
, remaining? A carbon dioxide laser device was used to test a flaky graphite cast iron specimen 6 of θ with an output of 1.0 Kll[, an irradiation speed of 1 sea, a pitch P of 5 cm, a quenching process of Σt-2,5■, a quenching depth of H
'l(0,3-9 laser hardened, output 1.0K
11[.

Irradiation speed 600-1, pitch P t 5 mm, in the chill layer! Nine specimens were laser-chilled to a temperature of 2.0 mm and a chill layer depth H of 0.5, and a reciprocating friction test was conducted to determine the scuffing limit load. The treated materials were tested.

Figure 7 shows a schematic diagram of the reciprocating friction testing machine used in the test. 7 is a mating bottle, and 8 is a hydraulic device for lifting the load.

Test conditions were stroke 50■ and friction speed i 1100c.
p, number of frictions total 200 cycles, load f 30kgf
The test was carried out at every 5 kgf up to 60 kgf. Lubrication is done in a so-called semi-dry manner, in which light oil is applied to the friction surface and then wiped with gauze.
A round bar with hard chrome plating applied to the tip to make the test surface spherical was used.

The method of determining the scuffing limit load is to apply friction up to 200 cycles under each load, mark those that did not cause scuffing during that period as good (○), and those that did cause scuffing as (×). ○) number is 5
The load obtained by 0% or more was defined as the scuffing limit load.

As is clear from the test results shown in Table 1, the laser-treated material according to the present invention exhibits a much higher scuffing limit load than the untreated material in both the quenched and chilled structures. and
It is clear that the scuffing resistance is excellent.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the amount of wear on the cylinder inner peripheral surface with respect to the position in the cylinder axial direction, Fig. 2 is an enlarged vertical cross-sectional view of the piston top dead center position of a conventional cylinder, and Fig. 3 is a main part of the cylinder according to the present invention. Longitudinal cross-sectional view, Figure 4 is a graph showing the amount of cylinder wear in Example 1 of the present invention, Figure 5 is a graph showing the amount of cylinder wear in Example 2 of the present invention, and Figure 6 is a graph showing the amount of cylinder wear in Example 2 of the present invention. FIG. 7 is a perspective view of the tested test piece and a schematic diagram of a reciprocating friction tester. 2...Top ring 6-...Hardened layer 4...
Cylinder. Representative Patent Attorney Yugawa Satoshi - 1 other person Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Procedural amendment May 31, 1982? 5 Permission Office Nagatomi Haruki Shimada 1 Small C indication 11d Sum 57 +1- Patent mft *TO14
735'i2, Issue #'lZ) Name: Hardening treatment place, has a 9-inner circumferential surface 3. Person making the correction: Relationship with cylinder 414: Applicant (11.jl, Mr. 9-9 Yaesu-chome, Chuo-ku, Tokyo). (Name) Tei 1 Piston Ring Co., Ltd. 4 Representative Agent 〒108 (1) Amend “Mu” in line 7 of page 8 of the specification to “B”. (2; Line 12 of page 8 of specification Correct as rAJ krCJ. (3) Specification 1g11, line 13 “Also on the sliding surface”?
Also, the sliding @ surface is corrected as "compared to cylinder Z'." (4) "Scuffing" in the rightmost column of Table 1 on page 14 of the specification is corrected to "scuffing." (5) Correct Figure 3 as shown in the attached drawing.

Claims (1)

[Claims] (1) A hardened layer is provided within the pressure ring sliding area on the inner peripheral surface of the cylinder, and the depth of the hardened layer is gradually shallowed in the axial direction toward the skirt side. A cylinder with a hardened inner surface. (2) The cylinder according to claim 1, wherein the hardened layer is laser hardened. (5) The cylinder according to claim 1, wherein the hardened layer is melted by a laser beam and has a chilled structure free of graphite precipitation. (4) The cylinder according to claim 1, wherein the hardened layer is melted with a laser beam to form a mixture of a chilled structure without nine graphite precipitation and a laser-hardened structure. (5) The cylinder according to claim 1, characterized in that in the cylinder, the hardened layers are provided with an interval between them.