JPH06238600A - Cut separation of sintered material - Google Patents

Abstract

PURPOSE:To surely carry out the cut from a prescribed part in a short time without using materials uselessly. CONSTITUTION:When a powder material is shaped to a prescribed shape, separation-predetermined parts 12a and 12b are shaped separately, and then the separation-predetermined surfaces 12c and 12d of the separation- predetermined parts 12a and 12b are closely attached, and sintering is carried out, keeping the separation-predetermined parts 12a and 12b in an integral form, and the load P in the cut separation direction is applied to the close attached part 12e of a sinterred member 11 formed through sintering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reliably breaking and separating a sintered body at a predetermined portion.

[0002]

2. Description of the Related Art Sintered metal is used in various fields because of its high productivity and easy mass production. 6 and 7 show a case where the connecting rod of the internal combustion engine is made of sintered metal. As is well known, the sintered metal is metal powder that is pressed into a predetermined shape and then sintered in a reducing atmosphere.

As shown in FIG. 6, a large end 2 is formed on one side of the connecting rod 1 and a small end 3 is formed on the other side. The large end 2 must be separated from the central part when it is mounted on a crankshaft (not shown). When the large end 2 is separated, as shown in FIGS. 8 and 9, for example, a cutter 4 for cutting the large end 2 by rotation is required, and the separation takes time. Also,
It is necessary to secure a cutting allowance W for the blade thickness of the cutter 4 in advance at the large end portion 2, which causes a problem in terms of material cost.

Therefore, without wasting the material,
It is desired to separate the large end portion 2 in a short time. Although not an example of a sintered metal, as an example of a technique for separating the large end portion of the connecting rod, for example, Japanese Patent Laid-Open No. 64-647
No. 29 publication is known. This publication discloses that a V-groove or the like is previously formed by machining at a predetermined site for fracture separation and is used as a fracture starting point.

[0005]

However, in this case, an apparatus for processing the V groove in the connecting rod is required, which causes a problem in cost. Further, when the breaking separation force is applied, the load is not always concentrated on the V groove, and there is a problem that the breaking occurs at a portion other than the breaking separation planned site.

It is an object of the present invention to provide a fracture separation method for a sintered body which can surely perform fracture separation from a predetermined portion in a short time without wasting material.

[0007]

A method for fracture separation of a sintered body according to the present invention for achieving this object is a method for fracture separation of a sintered body obtained by solidifying and burning powder. Then, when the powder is molded into a predetermined shape, the parts to be separated are separately molded, and then the surfaces to be separated of the parts to be separated are closely adhered to each other, and the parts to be separated are sintered in an integrated state,
The method comprises applying a load in the breaking separation direction to the contact portion of the sintered body produced by the sintering.

[0008]

In the fracture separation method for a sintered body having the above-described structure, at the time of sintering, the surfaces to be separated of the parts to be separated are brought into close contact with each other and the parts to be separated are integrated. . Here, although the powder is strongly bonded due to the sintering phenomenon due to the sintering, since the parts to be separated are separately pressure-molded separately in advance, the powder is mechanically bonded at the close contact part of the parts to be separated. The force is small, and even after sintering, the metallic bonding force in the contact portion is smaller than that in other portions.

After the sintering, a load in the breaking separation direction is applied to the close contact portion of the sintered body having a small metallic bonding force, so that the sintered body is easily broken and separated from the close contact portion. As a result, it is possible to reliably separate the fracture from a predetermined portion in a short time without wasting the material.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the fracture separation method for a sintered body according to the present invention will be described below with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a first embodiment of the present invention.
Especially, the case where the invention is applied to a connecting rod of an internal combustion engine is shown. FIG. 1A shows a connecting rod obtained by pressure-molding powder. Powder 10 shown in FIG.
Is made of, for example, iron powder to which copper powder, graphite and a lubricant are added. The powder 10 is pressure-molded into a shape as shown in FIG. 1A by a mold having a predetermined shape.

In FIG. 1A, the connecting rod 11 is composed of a large end portion 12, a small end portion 13 and a connecting portion 14. Usually, the large end 12 and the small end 13 are
Although connected through the connecting portion 14, in FIG. 1A, the large end portion 12 has the first large end portion 12a and the second large end portion 1
It is separated into 2 of 2b. The first large end portion 12a as a part to be separated is integrally formed with the connecting portion 14 and the small end portion 13. The second large end portion 12b as a part to be separated is pressure-molded separately from the first large end portion 12a.

At the first large end 12a, the planned separation surface 12 is formed.
c is formed. A planned separation surface 12d is formed on the second large end 12b. Plane for separation 12c, 12
d is located at the center of the large end portion 12 and is orthogonal to the center line A of the connecting rod 11.

As shown in FIG. 1B, the planned separation surface 12c of the first large end 12a and the planned separation surface 12d of the second large end 12b are adhered to each other before sintering. This close contact is performed, for example, via a jig (not shown), and this close contact state is maintained until the sintering work is completed. As shown in FIG. 1 (B), the connecting rod 11 to which the planned separation surfaces 12c and 12d are in close contact is heated in a reducing atmosphere and sintered.

When the sintering is completed, the powders are strongly metallically bonded to each other. FIG. 2 shows the planned separation surface 1 after sintering.
2c shows a close contact portion 12e between the planned separation surface 12d.
As shown in FIG. 2, since the first large end portion 12a and the second large end portion 12b are separately pressure-molded, the close contact portion 12e.
The powder 10 has a small mechanical binding force, and the metallic binding force in the contact portion 12e is smaller than that of other portions even after sintering.

Since the first large end 12a and the second large end 12b are joined by sintering, the separation surface 12c of the first large end 12a and the separation of the second large end 12b are planned. Face 12
The jig (not shown) that was in close contact with d is removed. Next, the connecting rod 11, which is a sintered body, is shown in FIG.
As shown in (C) of FIG. The breaking and separating mold 11 includes a left expansion mold 22 and a right expansion mold 2.
3 and wedge 24.

The large end hole of the large end portion 12 of the connecting rod 11 is broken. The left expansion mold 22 and the right expansion mold 2 of the separation mold 21.
When the wedge 24 is driven into the gap between the left expandable mold 22 and the right expandable mold 23 in a state of being fitted in 3, the large end 2 is subjected to a load in the breaking separation direction (arrow direction) due to the wedge effect. To do.

Since the close contact portion 12e between the planned separation surface 12c and the planned separation surface 12d after sintering has a smaller metallic bonding force than the other portions, the large end 12 is broken by the driving of the wedge 24 in the separation direction. When the load P acts, the contact part 1
Breaking starts from 2e as a starting point, and the large end 12 is separated into two.

Second Embodiment FIGS. 3 and 4 show a second embodiment of the present invention.
The second embodiment is different from the first embodiment only in the presence or absence of forging after sintering, and the other parts are the same as those in the first embodiment. Therefore, the same parts are denoted by the same reference numerals as those in the first embodiment. Therefore, the description of the corresponding parts will be omitted, and only different parts will be described.

The steps of FIGS. 3A and 3B are the same as those of FIG.
3 (A) and (B), and after the sintering operation in FIG. 3 (B) is completed, as shown in FIG. 3 (C), a connecting rod which is a sintered body is obtained. Eleven forging processes are performed. Since the sintered body is a manufacturing method in which powder is solidified and baked, voids remain in the sintered body. Therefore, in order to increase the fatigue strength of the sintered body, it is necessary to perform a forging process to eliminate the voids.

Connecting rod 11 which is a sintered body
Is compressed by a forging die (not shown), the holes in the sintered body are crushed, and the density of the connecting rods 11 becomes high. By this forging process, the degree of adhesion between the planned separation surface 12c of the first large end 12a and the planned separation surface 12d of the second large end 12b is also increased.

Here, as shown in FIG. 3B, when the connecting rod 11 is taken out of the sintering furnace after the sintering operation, the separation planned surface 12c of the first large end 12a is formed.
And the contact portion 1 between the planned separation surface 12d of the second large end portion 12b
Air enters the uncontacted portion of 2e. Therefore, the oxide film 16 is intermittently formed at the contact portion between the planned separation surface 12c and the planned separation surface 12d by the invading air, as shown in FIG.

The adhesion portion 12e on which the oxide film 16 is formed
Has a lower bonding force than the other parts of the sintered body, and as shown in FIG. 3D, when the load P in the fracture separation direction is applied to the large end portion 12, the oxide film 16 is Breakage starts from the formed contact portion 12e, and the large end portion 12 is separated into two.

Third Embodiment FIG. 5 shows a third embodiment of the present invention. In the first and second embodiments, the planned separation surfaces 12c, 12
Although d is linear, in the present embodiment, the first large end 12a is formed.
A concave portion 17a is formed on the planned separation surface 12c, and a convex portion 17b is formed on the planned separation surface 12d of the second large end portion 12b. The concave portion 17a and the convex portion 17b are adapted to fit together.

In the third embodiment constructed in this manner, when the connecting rod 11 is fractured and separated into the first large end portion 12a and the second large end portion 12b, the separation planned surface 12 is formed.
It is possible to forcibly form the concave portion 17a and the convex portion 17b in the c and 12d. Therefore, the work of assembling the first large end 12a and the second large end 12b becomes easy, and the assembling accuracy can be improved.

[0026]

According to the present invention, when the powder is molded into a predetermined shape, the parts to be separated are molded separately, and then the surfaces to be separated of the parts to be separated are brought into close contact with each other, and the parts to be separated are integrated. Since the load in the breaking and separating direction is applied to the contact portion of the sintered body produced by the sintering, the material is not wasted and the load from the predetermined portion is reduced in a short time. Break separation can be performed.

[Brief description of drawings]

FIG. 1 is a process drawing showing a manufacturing process of a connecting rod by a fracture separation method for a sintered body according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a bonded state of powders in the step (B) of FIG.

FIG. 3 is a process drawing showing a manufacturing process of a connecting rod by a fracture separation method for a sintered body according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a bonded state of powders in the step (C) of FIG.

FIG. 5 is a plan view showing a process of manufacturing a connecting rod by a fracture separation method for a sintered body according to a third embodiment of the present invention.

FIG. 6 is a plan view of a conventional connecting rod made of a sintered body.

7 is a cross-sectional view of FIG.

8 is a front view of a cutter used to separate the large end of the connecting rod of FIG. 6. FIG.

9 is a side view of the cutter of FIG. 8. FIG.

[Explanation of Codes] 10 Powder 11 Connecting Rod (Sintered Body) 12 Large End 12a First Large End 12b as a Part to Be Separated 12b Second Large End 12c as a Part to Be Separated 12c Separable Surface 12d Separation Planned surface 12e Adhesion part 16 Oxide film 21 Breaking separation mold

Claims (1)

[Claims] 1. A method for breaking and separating a sintered body obtained by solidifying and burning powder at a predetermined site, wherein separate parts to be separated are separately formed when the powder is formed into a predetermined shape, and , The surfaces to be separated of the parts to be separated are brought into close contact with each other, and the parts to be separated are sintered in an integrated state, and a load in the breaking separation direction is applied to the close contact part of the sintered body produced by the sintering. A characteristic method for fracture separation of a sintered body.