JPH06137316A - Manufacture of split bearing - Google Patents

Abstract

PURPOSE:To restrain deformation of a bearing part of a material to be worked by preventing a slip between the inner peripheral surface of a hole of the material to be worked and the outer peripheral surfaces of rupture dies. CONSTITUTION:In a manufacturing method of a split bearing to rupture and separate a bearing part of a material 1 to be worked by moving plural rupture dies 6 and 7 having an external shape to coincide almost with a bearing shape in a direction for separating from each other, rupture and separation are carried out by using the rupture dies 6 and 7 where a recess and projection shape is applied on the outer peripheral surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split bearing manufacturing method by fracture separation, and is used, for example, in manufacturing a large end bearing of a connecting rod of an internal combustion engine.

[0002]

2. Description of the Related Art A split bearing manufacturing method by fracture separation is
For example, it is disclosed in JP-A-64-64729. There, by inserting a plurality of split dies (cracking dies) into the large end hole of the connecting rod large end bearing part in which the cap and the main body are integrally molded, and moving the rupture dies in mutually opposing directions. , The large end is broken and separated into the cap and the body side.

[0003]

However, in the production of split bearings by fracture separation, for example, two fractured molds are moved in opposite directions so that the fractured molds contradict the integrated bearing portion of the workpiece. When the breaking load of
Before the bearing breaks, it extends in the load direction and becomes an oval,
A shape error will occur in the bearing after fracture. Such deformation of the work piece is accompanied by a slip between the inner peripheral surface of the hole of the work piece and the outer peripheral surface of the fracture type in contact with the inner peripheral surface of the hole. That is, since the friction between the inner peripheral surface of the hole of the workpiece and the outer peripheral surface of the fracture type is insufficient to prevent slippage, slippage occurs and the workpiece plastically deforms into an oval shape. Conversely speaking, if the slippage between the inner peripheral surface of the hole and the outer peripheral surface of the fracture type of the workpiece is stopped, the deformation of the bearing portion of the workpiece is suppressed, and the shape accuracy after fracture separation is improved.

The object of the present invention is to increase the friction between the inner peripheral surface of the hole of the workpiece and the divided outer peripheral surface of the breaking die to prevent slippage, and to increase the elongation at break of the workpiece. It is intended to provide a method for manufacturing a split bearing, in which the shape error of the entire area of the bearing portion after fracture is reduced by concentrating on

[0005]

The above object can be achieved by the following method of manufacturing a split bearing according to the present invention. That is, a plurality of breaking dies are prepared, the breaking dies are inserted into the holes of the bearing portion integrally formed with the workpiece, and a load is applied to the plurality of breaking dies to separate the breaking dies from each other. In the method of manufacturing a split bearing in which the bearing portion of the above is fractured and separated at a predetermined fracture surface, a fractured die is provided that has an uneven shape that is uneven in the radial direction on the outer peripheral surface, and when a fracture load is applied to the fractured die. The uneven shape of the outer peripheral surface of the break type is hard to fit into the inner peripheral surface of the hole in the bearing part of the work piece, while suppressing slippage between the outer peripheral surface of the break type and the inner peripheral surface of the hole part of the work piece A method of manufacturing a split bearing in which a breaking load is applied to the.

[0006]

In the split bearing manufacturing method of the present invention, when a breaking load is applied to the work piece from the breaking die, the convex and concave portions of the breaking die bite into the work piece in a small amount. And the coefficient of friction between the inner peripheral surface of the hole of the workpiece become large,
Slip between both sides stops. Therefore, the break-type uneven surface portion suppresses the elongation of the portion engaged with the uneven surface portion of the workpiece, and concentrates the elongation of the workpiece only at the planned break portion that is not engaged with the uneven surface portion. Let Therefore, the deformation of the bearing portion of the workpiece into the elliptical shape is suppressed, and the fracture also occurs with high accuracy on the expected fracture surface. After that, the bearing surface and the fracture surface are machined, but the amount of machining of the bearing member whose deformation into an ellipse is suppressed is small and the machining is easy.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a split bearing manufacturing method of the present invention will be described below with reference to the drawings. In FIG. 1, a work piece 1 is composed of, for example, a connecting rod of an internal combustion engine, in which case the split bearing 4 is a large end bearing, and is composed of a connecting rod body 2 and a cap 3. The large end bearing is in sliding contact with the crankpin of the crankshaft when assembled to the internal combustion engine. A joint surface (a predetermined fracture surface at the time of breaking) 5 between the connecting rod body 2 and the cap 3 is located in a plane that passes through the center of the large end hole and is orthogonal to the longitudinal axis of the connecting rod body 2.

As one method of manufacturing such a split bearing 4, the work piece 1 made of a rough material in which the cap and the connecting rod body are integrally formed is prepared by preliminary forging.
A plurality of breaking dies 6, 7 are inserted into the holes (large end holes) of the bearing portion of the workpiece 1, and a load is applied to the breaking dies 6, 7 in a direction to separate the breaking dies 6, 7 from each other. There is a fracture separation method in which the workpiece 1 is fractured and separated at a predetermined fracture surface (the portion of the joint surface 5). After the fracture separation, the inner peripheral surface and the joint surface 5 are machined.

In the present invention, as shown in the enlarged view of FIG. 2, the outer peripheral surface of the breakable dies 6 and 7 (the surface in contact with the inner peripheral surface of the bearing hole of the workpiece 1) has an uneven shape 8 which is uneven in the radial direction. Prepare the mold. When the breaking load is applied to the breaking molds 6 and 7, the tip of the convex portion of the concave and convex shape 8 is embedded in the hole inner peripheral surface 9 of the work piece 1 to increase the friction coefficient and to break the breaking mold. The purpose is to prevent slippage between the outer peripheral surfaces 10 and 11 of 6 and 7 and the inner peripheral surface 9 of the hole. In the example of FIG. 2, the concavo-convex shape 8 is formed on the entire outer peripheral surfaces 10 and 11 of the fracture molds 6 and 7. The teeth of the concavo-convex shape 8 have sharp tips, and the pitch P, the included angle θ of the valley, and the tooth height t are set to respective values that can prevent slippage. For example, the included angle of the valley θ
Is preferably 30 ° ≦ θ ≦ 90 °, and the tooth height t is t ≧
It is preferably 0.5 mm. This is because θ is 90 °
If it exceeds, it will be difficult for the teeth to dent into the work piece and θ will be 3
This is because if it is smaller than 0 °, the strength of the tooth becomes small, and t
Is less than 0.5 mm, the tip of the work piece may come into contact with the root of the tooth and the biting may be poor when the tooth is difficult to work.

Next, a plurality of breaking molds 6 and 7 are inserted into the bearing holes of the workpiece 1, and the outer peripheral surfaces 10 and 11 of the breaking molds 6 and 7 are brought into contact with the hole inner peripheral surface 9. At this time, a gap a is formed between the breaking dies 6 and 7. In the gap a, the outer peripheral surfaces 10 and 11 of the breakable dies 6 and 7 and the inner peripheral surface 9 of the hole do not contact each other,
In this portion, the work piece 1 is not restricted by the break dies 6 and 7. Then, the breaking dies 6 and 7 are positioned so that the predetermined fracture surface 5 of the workpiece 1 exactly coincides with the center of the gap a.

Next, the breaking molds 6, 7 are
A breaking load is applied in the direction in which 7 are separated from each other, and a breaking load is applied to the workpiece 1. The load may be applied by inserting a wedge into the gap a of the breaking molds 6 and 7 to push it apart, or as shown in FIG.
A load may be applied from the outside in a direction in which the plates 12 and 13 fixed to the plate are separated from each other. Plates 12 and 13 are guides 1
You will be guided at 4.

When a breaking load is applied, the tips of the teeth of the uneven shape 8 formed on the outer peripheral surfaces 10, 11 of the breaking molds 6, 7 are pressed against the inner peripheral surface 9 of the hole of the workpiece 1 to be processed. It is difficult to fit within 1. Therefore, the coefficient of friction in the circumferential direction between the rupturable outer peripheral surfaces 10 and 11 and the inner peripheral surface 9 of the hole becomes substantially infinite, and the surfaces 10 and 11 and the surface 9 do not slip in the hole circumferential direction. Therefore, even if a breaking load is applied, the work piece 1
At the portion of the uneven shape 8 that engages with the breaking dies 6 and 7, there is almost no circumferential extension and the circular shape is retained, and the bearing portion maintains a good circular shape even after the fracture. Then, the elongation is mainly concentrated on the portion having the uneven shape 8 that does not engage with the breaking dies 6 and 7, that is, the portion corresponding to the gap a. Therefore, the work piece 1 is fractured and separated at the central portion of the gap a with high accuracy. In order to make the fracture at the predetermined fracture surface more surely, a predetermined notch may be provided in the predetermined fracture surface portion of the work piece 1, or at the same time when the separating loads of the fracture molds 6 and 7 are applied. Alternatively, another wedge member may be provided earlier than that to make a notch with a predetermined fracture surface.

Due to the breakage, the work piece 1 is separated into the connecting rod body 2 and the cap 3. After the separation, the fracture surface 5 and the inner peripheral surface are cut. Such break-off and machine finishes have lower production costs than machine cuts and finishes. Further, since the bearing portion maintains a good circular shape due to the deformation constraint due to the engagement due to the concave-convex shape 8, as compared with the case where the circular precision of the inner peripheral surface is obtained by machining the conventional deformed oval shape. The cutting allowance is small, and the machining is easy, shortening the machining time, reducing the amount of cutting allowance,
Cost reduction can be achieved. After the fracture, but before finishing, the indentations of the teeth of the concavo-convex shape 8 remain on the inner peripheral surface of the bearing portion, but the depth is about 20 to 100 microns, and about 1 mm is provided for the finishing allowance by machining after the fracture. Since there is, the indentation disappears after machining and there is no problem.

In the examples shown in FIGS. 1 and 2, the elongation of the work piece 1 is concentrated in the portion corresponding to the gap a between the fracture molds 6 and 7, but this elongation concentrated portion is between the fracture molds 6 and 7. When it is desired to widen the gap a, as shown in FIG. 3, a toothless portion 15 having a toothless concave and convex shape may be formed in the breaking dies 6 and 7 in the vicinity of a predetermined cut surface 5 of the workpiece 1. . In the toothless portion 15, circumferential slippage is allowed to occur between the outer peripheral surfaces of the breakable dies 6 and 7 and the inner peripheral surface of the workpiece 1, and the workpiece 1 is locally localized at that portion. Can grow. Therefore, the stretched portion extends from the gap a in FIGS. 1 and 2 to the length b + of the toothless portion 15.
b '. By doing so, the flow of the stress lines in the predetermined fracture portion 5 of the work piece 1 becomes parallel, and a clean fracture surface can be obtained at the time of fracture.

[0015]

According to the present invention, since the fracture separation of the bearing portion of the work piece is performed by using the fracture mold having the irregular shape on the outer peripheral surface, the irregular shape is applied when the fracture load is applied. The tips of the teeth are difficult to work, and the elongation of the part of the work that is engaged by the break type and the uneven shape is suppressed, and the elongation is concentrated in the part that is not engaged with the break type uneven shape. To do. As a result, it is possible to prevent the bearing portion from being excessively deformed, and to reliably cause a fracture at a predetermined fracture surface, and it is possible to manufacture a split bearing with high accuracy.

[Brief description of drawings]

FIG. 1 is a front view of an apparatus for carrying out a method of manufacturing a split bearing according to an embodiment of the present invention.

FIG. 2 is an enlarged front view of the apparatus of FIG. 1 in the vicinity of a bearing of a fractured die and a workpiece.

FIG. 3 is an enlarged front view of a fractured die and a vicinity of a bearing portion of a workpiece, which are used in a method of manufacturing a split bearing according to another embodiment of the present invention.

[Explanation of symbols]

 1 Workpiece 2 Connecting rod main body 3 Cap 4 Split bearing 5 Predetermined fracture surface 6 Fracture type 7 Fracture type 8 Concavo-convex shape 9 Hole inner peripheral surface 10 Fracture type outer peripheral surface 11 Fracture type outer peripheral surface 12 Plate 13 Plate 14 Guide 15 Missing teeth Department

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[Procedure amendment]

[Submission date] December 24, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

In the split bearing manufacturing method of the present invention, when a breaking load is applied to the work piece from the breaking die, the convex and concave portions of the breaking die bite into the work piece in a small amount. And the coefficient of friction between the inner peripheral surface of the hole of the workpiece become large,
Slip between both sides stops. Therefore, the break-type uneven surface portion suppresses the elongation of the portion engaged with the uneven surface portion of the workpiece, and concentrates the elongation of the workpiece only at the planned break portion that is not engaged with the uneven surface portion. Let Therefore, the deformation of the bearing portion of the workpiece into the elliptical shape is suppressed, and the fracture also occurs with high accuracy on the expected fracture surface. After that, the bearing surface is machined, but the amount of processing of the bearing member whose deformation into an ellipse is suppressed is small, and the processing is easy.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

As one method of manufacturing such a split bearing 4, the work piece 1 made of a rough material in which the cap and the connecting rod body are integrally formed is prepared by preliminary forging.
A plurality of breaking dies 6, 7 are inserted into the holes (large end holes) of the bearing portion of the workpiece 1, and a load is applied to the breaking dies 6, 7 in a direction to separate the breaking dies 6, 7 from each other. There is a fracture separation method in which the workpiece 1 is fractured and separated at a predetermined fracture surface (the portion of the joint surface 5). After fracture separation, the inner peripheral surface is machined.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

Due to the breakage, the work piece 1 is separated into the connecting rod body 2 and the cap 3. After the separation, the inner peripheral surface is cut. Such break-off and inner peripheral machining finishing requires lower production costs than cutting and finishing by machining. Also,
Since the bearing portion maintains a good circular shape due to the deformation constraint due to the engagement due to the concavo-convex shape 8, compared with the case where the circular shape of the inner peripheral surface is obtained by machining the deformed oval shape as in the conventional case, the cutting allowance is increased. It also requires less amount of time and is easier to process, which shortens the processing time, reduces the cutting margin, and reduces the cost. After rupture and before finishing, the indentations of the teeth of the uneven shape 8 remain on the inner peripheral surface of the bearing portion, but the depth is 2
Since it is about 0 to 100 μm and the machining allowance after breaking is provided with about 1 mm, there is no problem because the indentation disappears after machining.

Claims (1)

[Claims] 1. A plurality of breaking dies are prepared, the breaking dies are inserted into holes of a bearing portion integrally formed with a workpiece, and a load is applied to the plurality of breaking dies in a direction of separating the breaking dies from each other. In the method of manufacturing a split bearing in which the bearing part of the work piece is fractured and separated at a predetermined fracture surface, prepare a fractured die with a concave and convex shape in the radial direction on the outer peripheral surface, and apply a fracture load to the fractured die. When actuated, the uneven shape of the outer peripheral surface of the fracture mold is hard to fit into the hole inner peripheral surface of the bearing part of the workpiece to suppress slippage between the outer peripheral surface of the fracture mold and the inner peripheral surface of the hole of the workpiece bearing part. At the same time, a breaking load is applied to the work piece, and a method for manufacturing a split bearing.