JPH0454340Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Industrial application field) The invention relates to a half-split plain bearing.
This relates to a half-split plain bearing in which eccentric finishing is applied to the entire inner circumferential surface of the overlay plating layer.

(Prior Art) Conventional sliding bearings include a half type 10 and a bush type 11 shown in FIGS. 3A and 3B. As shown in FIG. 4, each of these is constructed by lining a back metal 3 made of a steel plate on the outer peripheral side with a bearing alloy layer 2, and further plating an overlay plating layer 1a containing lead as a main component. The thickness of the overlay plating layer 1a is approximately 20 μm as a standard, and is obtained with a manufacturing tolerance of ±4 μm.

The purpose of forming the overlay plating layer 1a is to
The purpose is to bury foreign particles that enter the oil clearance between the sliding friction surface of a sliding bearing and the shaft into a soft overlay plating layer 1a, thereby preventing seizure and improving compatibility with the shaft. Note that the overlay plating layer 1a
By making the thickness thinner than the standard value of 20 μm, the load bearing capacity and fatigue strength will improve, but the embeddability will decrease, and by making it thicker than the standard value of 20 μm, the relationship will be reversed. It is known.

(Problems to be solved by the invention) The overlay plating layer 1a forming the sliding friction surface of the above-mentioned conventional sliding bearing, in which the overlay plating layer 1a forms a cylindrical surface, is as follows:
It was formed through a plating process so that its wall thickness was uniform. That is, the cylindrical overlay plating layer 1a was given a uniform thickness at the center and end portions in the circumferential direction of the plain bearing. As a result, it was not possible to achieve good compatibility between the aforementioned embeddability, load resistance, and fatigue resistance, or to improve the lubrication performance.

(Means for Solving the Problems) The present invention has been made in view of the above circumstances, and consists of a half-split plain bearing consisting of a backing metal, a bearing alloy layer, and an overlay plating layer sequentially from the outer circumferential side. , eccentric finishing is applied to the inner peripheral surface of the overlay plating layer, which is pre-plated thicker than the required wall thickness, so that the thickness in the central axis direction is equal,
This is a half-split sliding bearing in which an overlay plating layer having different thicknesses at the center and both ends in the circumferential direction is formed so that the inner circumferential surface that becomes the sliding friction surface forms a cylindrical surface.

(Function) The overlay plating layer of this half-split plain bearing is formed thicker at the center in the circumferential direction than at the ends, depending on how the tool is eccentrically placed during eccentric finishing, and in other cases. In some cases, the center portion in the direction is formed thinner than the end portions.

If the overlay plating layer is formed so that the center part in the circumferential direction is thinner than the end parts, for example, when applied to the big end of the piston rod of an engine, the overlay plating layer will be thinner than the overlay plating layer of equal thickness. As a result, it is possible to improve the load resistance and fatigue resistance at the center portion, which receives the maximum load, and to ensure the ability to embed foreign matter at the end portions. In addition, if the overlay plating layer is formed so that the center part in the circumferential direction is thicker than the end part, when similarly applied to the large end of the piston rod, it will be compared to a case where an overlay plating layer of equal thickness is formed. As a result, the center part has good foreign matter embedding property, and a large lubricating oil reservoir is secured at the end parts, so the oil circulation is improved.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the main parts of a half-split plain bearing according to a first embodiment of the present invention.

First, a bearing alloy layer 2 is lined on the inner circumferential surface of the backing metal, and an unprocessed overlay plating layer 1a' is applied to the inner circumferential surface of the bearing alloy layer 2 to a thickness thicker than the required thickness as shown by the imaginary line. It was formed into a semi-cylindrical shape in the plating process. The overlay plating layer 1a' mainly contains lead, for example, copper: 2.5%, tin: 10%, lead:
Consists of residue. Specifically, it was formed with a thickness W of 35 μm. Thereafter, eccentric finishing is applied to the entire inner circumferential surface of the semi-cylindrical overlay plating layer 1a' before processing at room temperature, and a backing metal or An eccentric cylindrical surface was formed on the bearing alloy layer 2. This eccentric finishing is performed, for example, by cutting with a cutting tool whose axis is placed a predetermined amount closer to the center A side with respect to the central axis of the overlay plating layer 1a'. As a result, the circumferential center part A and both ends are smoothly connected on the cylindrical surface, and the thickness in the center axis direction is equal, and the circumferential center part A is thinner than both ends. Layer 1' is formed. Specifically, the thickness W _B of the central part A is 15 μm, and the thickness W _A of both ends is
were each formed to a thickness of 20 μm. The overlay plating layer 1' after processing has the same thickness in the central axis direction on the sliding friction surface portion excluding oil grooves, oil holes, etc. (not shown).

According to such a half-split sliding bearing, the entire sliding friction surface of the overlay plating layer 1' after processing is
Finishing by cutting ensures a finished surface roughness of 1S, and the variation in the thickness of the overlay plating layer 1' for each bearing can be kept within ±2 μm, achieving practically satisfactory accuracy. It was done.

In addition, when this half-split plain bearing is used, for example, at the big end of the piston rod of an engine, the load resistance and fatigue resistance at the circumferential center part A, which receives the maximum load, will improve, and the maximum load will be Metal abrasion powder, foreign matter in lubricating oil, etc. can be well buried at both ends where no action is taken. As a result, it is possible to satisfactorily achieve both load resistance, fatigue resistance, and foreign matter embedding property, which cannot be achieved with an overlay plating layer of equal thickness.

FIG. 2 shows the main parts of a half-split plain bearing according to a second embodiment of the present invention.

In this embodiment, first, a bearing alloy layer 2 is lined on the inner circumferential surface of the back metal, and this bearing alloy layer 2 is
As shown by the imaginary line, an unprocessed overlay plating layer 1a' was formed in a semi-cylindrical shape on the inner circumferential surface of the plating process to a thickness greater than the required thickness, specifically, a thickness W of 35 μm. Thereafter, eccentric finishing is applied to the entire inner circumferential surface of the semi-cylindrical overlay plating layer 1a' before processing at room temperature, and the inner circumferential surface of the overlay plating layer 1a' is coated with the backing metal or bearing alloy layer 2. In contrast, an eccentric cylindrical surface was formed. This finishing process is performed, for example, on the overlay plating layer 1.
Cutting is performed using a cutting tool whose axis is placed a predetermined distance away from the center A side with respect to the central axis of a'.

As a result, the circumferential center part A and both ends are smoothly connected on the cylindrical surface, and the overlay plating after processing is made such that the thickness in the center axis direction is equal and the circumferential center part A is thicker than both ends. Layer 1'' was formed. Specifically, the thickness W _B of the central part A was formed to 20 μm, and the thickness W _A of both ends was formed to 15 μm. Note that the overlay plating layer 1'' after processing was formed. teeth,
The thickness in the central axis direction is the same, except for oil grooves, oil holes, etc. (not shown).

According to such a half-split plain bearing, in finishing processing by cutting, the entire sliding friction surface of the overlay plating layer 1'' after processing has a finished surface roughness of 1S.
was ensured, and a practically satisfactory effect was obtained as in the first embodiment.

In addition, when this half-split sliding bearing is used, for example, at the large end of an engine's piston rod, both ends are machined to be thinner than the center part A in the circumferential direction.
It is possible to embed foreign matter in the center, and at both ends where the maximum load is not applied, a relatively large gap is secured between the shaft and the crankshaft. Therefore, the ability to retain lubricating oil at both ends is improved, and the flow of oil to the sliding friction surface is improved compared to an overlay plating layer of equal thickness. As a result, it helps prevent seizure.

In each of the above examples, the inner circumferential surface of the overlay plating layer was finished by cutting, but this is because the overlay plating layer is mainly composed of lead, which is a soft metal, and a grinding tool was not used. Even eccentric grinding is not impossible.

(Effects of the invention) As understood from the above explanation, the half-split sliding bearing according to the invention provides the following effects.

(b) Since eccentric finishing is applied to the entire inner circumferential surface of the overlay plating layer, which becomes the sliding friction surface, this finishing process not only provides a high degree of finishing accuracy for the sliding friction surface, but also creates a semi-cylindrical shape. This process is efficient because the thickness of the overlay plating layer is made different at the center and at the ends in the circumferential direction at the same time.

In addition, since the overlay plating layer has the same thickness in the central axis direction, it is possible to perform eccentric finishing continuously with multiple half-split plain bearings arranged abutting each other in a semi-cylindrical shape. and has good processing efficiency. Furthermore, by eccentric finishing, the sliding friction surface is formed into a cylindrical surface eccentric from the rotation center of the shaft, and the circumferential center and end portions, which have different thicknesses, are connected with an extremely smooth curved surface. Discontinuity of the lubricating oil film is less likely to occur and a good lubricating oil film can be formed.

(b) If the overlay plating layer is formed so that the center part in the circumferential direction is thinner than both ends, the load resistance and fatigue resistance at the center part will be improved, and foreign matter will not be buried at the ends. Yield can be ensured. As a result, when used, for example, at the large end of a piston rod in a high-load engine, it is possible to achieve both load resistance, fatigue resistance, and embeddability, and the life of the half-split plain bearing is significantly extended.

(c) If the overlay plating layer is formed so that the center part in the circumferential direction is thicker than both ends, the oil circulation will be improved and the lubrication performance will be improved. Coupled with the fact that the bearings are connected with an extremely smooth curved surface, seizing is prevented when used, for example, at the large end of a piston rod in an engine with a low load, and the life of the half sliding bearing is significantly extended.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the main parts of the first embodiment of the present invention,
FIG. 2 is a diagram showing the main parts of the second embodiment, and FIG.
Figures A and B are perspective views showing the half-split type and bush type of the sliding bearing, respectively.
It is an enlarged view of each part A of (b). 1', 1''...overlay plating layer, 1a'...
Overlay plating layer before finishing processing, 2... Bearing alloy layer, W... Thickness of overlay plating layer before finishing processing, W _A , W _B ... Thickness of overlay plating layer after finishing processing.

Claims (1)

[Scope of utility model registration request] In a half-split plain bearing consisting of a backing metal, a bearing alloy layer, and an overlay plating layer in order from the outer circumference, eccentric finishing is performed on the inner circumferential surface of the overlay plating layer, which is plated thicker than the required wall thickness in advance, and An overlay plating layer having the same thickness and different thicknesses at the center and both ends in the circumferential direction is formed so that the inner circumferential surface serving as the sliding friction surface forms a cylindrical surface. Plain bearing.