JPS61137641A - Manufacture of connecting rod - Google Patents

Abstract

PURPOSE:To produce a connecting rod which has no defects such as bent and has a good shape by a closed-die forging method at a high material yield and with simple means by using a blank which is preliminarily produced by taking the metal distribution in the longitudinal direction of the connecting rod into consideration. CONSTITUTION:Such blank 10 which suppresses the flow of the metal in the longitudinal direction at the large end and small end of the connecting rod 1 and forces quickly the material to arrive in the direction intersecting orthogonally therewith is prepd. More specifically the metal of the material in the part 11 corresponding to at least, for example, the large end 2 is made into a spherical shape or the shape resembling thereto. Upper and lower punches 6a, 6b, 7a, 7b are first fixed in the retreat position of the stroke shown in the figure. The blank 10 is then imposed between upper and lower dies 5a and 5b and is thereafter compressed by the dies 5a, 5b by which an I section part 4 is formed to the prescribed shape. While the dies 5a, 5b are held closed, the stock is compressed by the punches 6a, 6b, 7a, 7b, by which only the large end 2 and small end 3 are formed to the prescribed shape.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to forging technology, and more specifically, in the production of connecting rods or connecting rods (hereinafter referred to as "connecting rods"), defect-free connecting rods are manufactured by closed forging. Relating to a method of manufacturing.

(Prior Art and Problems) Conventionally, connecting rods for automobiles and the like are manufactured by a forging method, and the large and small ends thereof are subjected to finishing processes such as drilling and cutting.

Connecting rods are generally forged by using a round bar cut to an appropriate length as a raw material, heating it, free forging it with a hammer to form a blank material, and then producing it by a paring forging method. However, with this manufacturing method, the material yield is approximately 50% due to the large gripping and breaking parts of the material.
That's extremely bad.

Closed forging methods or closed forging methods have been attempted as a means to improve such low yields, but the current situation is that they have not yet reached the stage of practical use. That is,
In particular, the details and problems of the closed forging method are as follows.

The closed forging method will be explained with reference to FIGS. 4 to 6 when manufacturing the cooking stove 1.

The large end 2 and small end 3 can be filled with meat by making the die a double-acting type, but the I-cut section 4 cannot be filled with meat because there is no material flow in the longitudinal direction. The problem is that it is a national policy.

Therefore, attempts have been made to perform closed forging of this I-cuff 23 part 4 as a vertically moving type or a double acting type only on one side. That is, as shown in FIG. 5, first, upper and lower dies 5a, 5b equipped with upper and lower punches 6a, 6b, 7a, 7b
The material is compressed by

The large end and small end are compressed by upper and lower punches 6a, 6b, 7a, 7b as the first punch.

On the other hand, the flesh of the L section fills the hole of the upper die 5a (or lower die 5b) serving as a closing mold due to compression by the dies 5a and 5b, and then is inserted into the upper die 5a as a second punch. The I section portion is compressed by the operation of the punch 8. However, in this case, since the meat did not flow in the longitudinal direction, it was not possible to prevent folding flaws 9 (FIG. 6) from occurring at both longitudinal ends of the punch 8.

(Object of the Invention) In view of the extremely low material yield achieved by the conventional forging method described above, the present invention improves the closed forging method to make it possible to improve the material yield by a rational and simple means, and
The object of the present invention is to provide a new method for manufacturing a connecting rod without folding defects.

(Structure of the Invention) In order to achieve the above object, the present inventors conducted various experiments and conducted research to investigate the cause of folding defects caused by the double action of the section section and countermeasures for the above-mentioned closed forging method. As a result of overlapping, if the shape of the forged material is manufactured with due consideration to the longitudinal thickness distribution of the forged product (conrod), it can be made into an integral structure with the upper and lower gougs instead of being a double-acting type using punch 8. It has been found that there is no occurrence of cracks, and that a predetermined product shape can be obtained at both the I section, large end, and small end due to the swelling of the meat, and no folding defects occur.

That is, the present invention provides closed forging of a connecting rod,
By using a pre-manufactured material that takes into account the longitudinal thickness distribution of the connecting rod, the double-acting type can be omitted for the (2) section section and it can be made integral with the upper and lower gougers.

First, as a first punch, a closed mold divided into two parts is used to compress the mold, and then, as a second punch, only the holes at the large and small ends of the connecting rod are compressed using an upper punch and a lower punch, respectively. The purpose is to fill the specified amount of meat.

The present invention will be explained in detail below with reference to the drawings.

First, the material to be subjected to the closed forging of the present invention has a specific shape, and the shape needs to take into consideration the longitudinal thickness distribution of the connecting rod.

In other words, in the forging according to the present invention, the flow of the material in the longitudinal direction at the large and small ends of the connecting rod is suppressed, the material is quickly allowed to reach the direction perpendicular to this, and then the material flows into the central hole. In order to increase the thickness of the connecting rod, the shape is designed to take into account the distribution of the meat in the longitudinal direction.1For example, as shown in FIG. Make the material into a spherical shape or a shape similar to it (for example, approximately spherical, polyhedral, etc.).

The material of the portion 12 corresponding to the small end may also have a similar shape.

The shaped material 10 having such a shape can be easily manufactured by a well-known forging method, such as rotary forging or cross rolling.

The raw material 10 is forged into a connecting rod of a predetermined shape through the steps described below.

The configuration of the die used is as shown in Figure 1.
The divided closing mold is provided with upper punches 6a, 7a and lower punches 6b, 7b for compressing only the holes at the large end and small end of the connecting rod.

Each die has a unitary construction without the need for a punch as shown in FIG.

First, before performing closed forging of the material 10 as a first punch, the lower punches 6a, 6b, 7a, and 7b are fixed at the stroke retreat position shown in FIG.

In this state, the material 1"0 is placed between the upper and lower dies 5a and 5b, and then compressed by the upper and lower dies 5a and 5b.

This gives the I-section portion a predetermined shape.

Next, as a second punch, with the upper and lower dies 5a and 5b closed (compressed state 1fA), as shown in FIG.
2. Compression is performed using the lower punches 6a, 6b, 7a, and 7b, and only the large end and small end become the predetermined shape.

The connecting rod 1 thus obtained has no folding flaws at the large end or small end, and of course, no bending flaws at the I section, and can be manufactured at an extremely high yield.

(Example) A molded material having the shape shown in FIG. 3 was manufactured by rotary forging using two types of materials: Cr-Mail and Ti alloy. This was subjected to closed forging of the first punch using a die having the configuration shown in Fig. 1, and then punching of the second punch was performed (
Example of the present invention). For comparison, a connecting rod was manufactured by rotating the forged material (comparative example). In addition,
In both methods, the forging temperature was 1100°C.

As a result, in the example of the present invention, the material yield (
(excluding scale loss) was 100%,
In the comparative example, it was 95%. While the material yield when using the conventional free forging method is extremely poor at about 50%, the present invention can improve the yield to 100% as described above, which is compared to the comparative example using the improved formed material. It has also improved compared to other countries.

(Effects of the Invention) As detailed above, according to the present invention, connecting rods with good shapes and no defects such as folding defects can be manufactured using a closed forging method at an extremely high material yield and by simple means. This has great effects, such as making it practical to manufacture connecting rods by closed forging.

[Brief explanation of drawings]

1 to 3 are diagrams explaining an embodiment of the method of the present invention, in which FIG. 1 is a sectional view showing the first punching step, and FIG. 2 is a sectional view showing the second punching step.
Figure 3 is a cross-sectional view showing the punching process, Figure 3 is a vertical cross-sectional view showing an example of the shape of the material, and Figure 4 is a plan view of the connecting rod. 5 and 6 are views for explaining the conventional method. FIG. 5 is a cross-sectional view showing the conventional closed forging method, and FIG. 6 is an explanatory view showing folding defects caused by earth removal. 1... Connecting rod, 2... Big end, 3... Small end, 4... I section part. 5a...upper die, 5b...lower die. 6a, 7a...upper punch, 6b, 7b...lower punch, 8...punch, 9...folding flaw. 10... Formed material, 11... Large end portion equivalent,
12... Portion corresponding to the small end. Patent applicant: Daido Steel Co., Ltd. Patent attorney Hisashi Nakamura Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] When manufacturing a connecting rod by closed forging, a material manufactured with consideration to the longitudinal thickness distribution of the connecting rod is used, and a closed mold divided into two upper and lower parts is used as a first punch to compress the material, and then a second punch is used to compress the connecting rod. A method for manufacturing a connecting rod, comprising compressing only the holes at the large end and small end of the connecting rod using upper and lower punches as punches.