JPH06190492A - Formation of member having h-shaped cross section - Google Patents

Abstract

PURPOSE:To obtain a forging means, in which rising of the forming load and the die surface pressure at the time of forging is restrained and the formation of a member having thin H-shaped cross section can be executed. CONSTITUTION:At the time of forming the H-shaped cross sectional part in 'the member having H-shaped cross sectional part' by forging, in a first process, in the condition of arranging one pair of side surface tools 4, 4' having mountain type cross section faced to the die surfaces in which the slopes continue while retreating to the vertical direction from R parts projected at the center part, at both side of the blank 2, one pair of upper and lower tools 5, 5' are approached to execute the reverse extrusion to the blank to form an H-shaped cross sectional web part and a half-forming flange part. Successively, in a second process, instead of the side surface tools 4, 4' having mountain type cross section, by using one pair of side surface tools 6, 6' having flat die surface and also by pressing the half-forming product from both sides in the condition of fixing the position of the upper and lower tools 5, 5', while remaining little recessed parts 7, 7' in the center part of the outer side surface of the half- forming flange till completing the working, the compression and the bending are executed to the half-forming flange part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin H-shaped cross section such as "beam part of connecting rod for automobiles" by forging.

[0002]

2. Description of the Related Art Generally, when forming an H-shaped cross section on a part of a metal member by forging, a pair of side surface tools 1 and 1'having flat mold surfaces are provided on both sides of a blank 2 as shown in FIG. A method is employed in which a pair of upper and lower tools 3, 3'are brought close to each other in a state of being arranged on a surface and reverse extrusion (indirect extrusion) is performed by each of these upper and lower tools.

However, the thickness of the flange of the molded member (see FIG.
When t _f ) is thin, the surface pressure applied to the mold (tool) becomes extremely high and the life of the mold becomes extremely short according to the above method. Therefore, it is difficult to form such a member by forging. It is said to be impossible.

For example, a connecting rod, which is an important constituent member of an automobile engine section, comprises a small end portion, a beam portion and a large end portion, as shown in FIG. As shown in FIG. 9, the cross-sectional shape of the beam portion is H-shaped, which consists of the flange portion and the web portion, but the beam portion tends to become thinner and thinner with the development of high-strength materials, and only forging is required. It is becoming difficult to mold by molding.

Therefore, recently, a) the thickness of the flange portion and the thickness of the web portion (t _{w in} FIG. 7).
Is forged so that the surface pressure applied to the mold does not become excessively high, and is then forged by machine cutting to finish thin, b) Finishing everything from the material by machining The current situation is to deal with this by methods, and there was a considerable disadvantage in terms of manufacturing efficiency and material yield.

On the other hand, on the other hand, development of a mold material having excellent wear resistance capable of withstanding a high surface pressure has been carried out (for example, in JP-A-62-180033, a chemical composition is devised). However, even if the mold material is improved, it is necessary to enlarge the equipment because a high processing load is required to form a thin material, which is not always industrially advantageous. I couldn't say it was a good way.

However, from the viewpoint of reducing the load during forming, the processing is temporarily interrupted during the forging and a hole is made in the center of the semi-finished product to smooth the material flow (in the direction of the hole) A proposal (Japanese Patent Publication No. 62-33015) to continue the process from the fact that a material flow also occurs), but this method can be applied to a hole in the central portion such as a gear. It was limited to the manufacture of products.

In view of the above, the object of the present invention is to suppress the increase of molding load and mold surface pressure, which are problems at the time of manufacturing a thin-walled member by forging, and to reduce the mold life (mold surface pressure). Is one of the major factors that determine the life of the mold), and the like, was to establish a forging means for enabling the formation of a member having a thin H-shaped cross section that could not be processed by forging. .

[0009]

The present invention has been completed based on the results of research conducted by the present inventor who has been earnestly conducted to achieve the above object. When forming the H-shaped cross-section of the “member having”, as shown in FIG. 1, in the first step, a pair of “R-parts (rounded parts) protruding in the center from the pair of“ R-parts (rounded parts) which are inclined planes are A pair of vertical tools 5, with the side tools "4, 4'having a chevron-shaped cross section with the die surfaces facing each other retracted in the vertical direction, are arranged.
5'approach and reverse extrusion of the material is performed to form the H-section web part and the semi-formed flange part. In the second step that follows, instead of the side surface tools 4, 4'having a chevron cross-section, a pair of flat mold surfaces is used. By using the side tools 6 and 6'and pressing the semi-molded product from both sides with the positions of the upper and lower tools 5 and 5'fixed, the central part of the outer surface of the semi-molded flange may be slightly pressed until the end of processing. By compressing and bending the semi-formed flange while leaving the recesses 7 and 7 ', it is possible to forge a member with an H-shaped cross section under a low forming load and mold surface pressure. " It has a great feature.

[0010]

That is, according to the present invention, the forming step is divided into two steps when forming the H-shaped cross section of a "member having an H-shaped cross section" such as a connecting rod for automobiles. First, in the first step, Unlike the conventional method shown in FIG. 7, as the side surface tools, tools 4, 4'having an appropriate inclination angle .alpha. And a tip rounding radius R on the working surface as shown in FIG. 1 are used. Then, the processing material 2 is placed in between, and these are opposed and fixed at a predetermined interval.

Then, in this state, the same pair of upper and lower tools 5 and 5'as in the conventional method are brought close to each other to perform reverse extrusion (indirect extrusion) of the material to form a semi-finished product before reaching the H-shaped cross section. (Process shown in the center of FIG. 1). Here, in this semi-finished product, the web part is finished to the dimensions of the final product, but the flange part has a shape that opens outward along the working surface of the side tools 4, 4 ′ and has a thickness. It is made thicker than the product thickness. The thickness of the semi-formed flange portion is adjusted by the side tool tip position L shown in FIG.

In this way, in the first step of reverse extrusion of the material, the working surfaces of the side tools 4, 4'corresponding to the container are mountain-shaped, and the thickness of the semi-formed flange is increased. Since the material flow is very smooth, the surface pressure applied to the tool when the semi-formed flange is formed by the material flow is very small.

Next, the second step (step shown at the right end of FIG. 1) starts. In the second step, with the upper and lower tools 5, 5'fixed at the final position of the first step, the side surface tools 4 and 4'having the chevron side surface are used instead of the working surface (mold surface). This is a process of pressing the semi-formed flange portion from both sides with flat side tools 6, 6 ', bending and reducing the thickness of the semi-formed flange portion, and adjusting the H-shaped cross-sectional shape and dimensions to that of the final product.

The pressing / compression molding of the semi-molded flange portion by the side surface tools 6, 6'having flat working surfaces is performed by pressing the outer surface of the semi-molded flange central portion (side surface tool having a chevron-shaped working surface) until the molding is completed. (The part where the rounded tip R of 4, 4'abuts)
Is carried out with some recesses 7 and 7'remaining (the depth of this recess is basically determined by the side tool tip position L having the above-mentioned chevron working surface).

As a result, the flow of the material is not limited to the direction of the flange end portion (see FIG. 3) as in the conventional method, but as shown in FIG. Occurs in both directions (the direction of the depression), and therefore the material flow is easy and smooth even in this second step,
It is possible to minimize the "contact pressure applied to the mold", which has a great effect on the life of the mold (tool).

Next, the present invention will be described with reference to examples.

EXAMPLE "The surface pressure applied to a mold (tool)" when forming an H-shaped cross section according to the process of the present invention shown in FIG. 1 was investigated and compared with that in the conventional method (the method shown in FIG. 7). did.

Here, since the maximum surface pressure which is actually a problem in the process shown in FIG. 1 is applied in the "second process using a side tool having a flat working surface", the surface pressure in the second process is used in this embodiment. Was surveyed.

Since it is difficult to experimentally check the surface pressure applied to the die, as shown in Table 1, the values to be changed are "side tool inclination angle α", "side tool tip radius R" and "side tool tip radius R". The side-tool tip position L ″ was taken (in the present invention examples, all were values in the first step), and simulation was performed using the rigid-plastic finite element method capable of deformation / temperature coupled analysis.

[0019]

Table 2 shows the calculation conditions in that case. The deformation resistances shown in Table 2 were determined by assuming steel equivalent to S35C. Further, the pressurizing speed is a value determined by assuming a hydraulic press. Furthermore, the coefficient of friction is due to Coulomb friction.

[0021]

[Table 2]

The calculation results by the simulation performed under such conditions are summarized and shown in FIG. Figure 5
As is clear from the results shown in Fig. 1, in the conventional example, the surface pressure exceeds 100 kgf / mm ² , whereas in the present invention example, when the side tool tip radius R in the first step is too small, The dent that occurs on the outer surface of the product flange becomes sharp, and in order to eliminate this, the surface pressure applied to the side tool in the second step must be increased, but if the side tool tip radius R is selected properly, the maximum It can be seen that the surface pressure is 88 kgf / mm ² , which is approximately 13% lower than that of the conventional example.

Further, in addition to the above simulation, a molding experiment according to the present invention was carried out by using a material that is easy to mold and a plane strain was assumed, and compared with that of the conventional method. In this experiment, lead was used as a material that can be easily molded, and a "die that can be uniformly compressed vertically by a spring 8" as shown in FIG. 6 was used as a test device. Here, in the mold device according to the present invention, the side surface tool 9,
9 ', and in the second step, the upper and lower tools 10, 10' were each constructed as a container.

Even in this case, since it is difficult to experimentally obtain the surface pressure applied to the mold, it was estimated by measuring the load. The results of this experiment are shown in Table 3.

[0025]

From the results shown in Table 3, the molding load is
It can be seen that when the conventional method was 4.71 tons, when the method of the present invention was used, it was reduced to 3.88 tons by 17%.

In the above description, hot steel was assumed, but in the method of the present invention, the temperature at the time of processing is not particularly limited, and the material is not particularly limited, It is needless to say that the present invention can be applied to the plastic working material of No. 3, and can be applied to the manufacture of any product having an H-shaped cross section. Of course, the shape of the material and the shape of the mold (tool) can be arbitrarily selected.

[0028]

[Summary of Effects] As described above, according to the present invention, since the flow of the material during molding can be made smooth in two directions, the surface pressure applied to the mold (tool) can be made extremely small and high. The H-shaped cross section of the "member having the H-shaped cross section" can be forged under the life of the die, making it possible to mass-produce even a member having a thin H cross section at low cost and stably. , The industrially useful effect is brought about.

[Brief description of drawings]

FIG. 1 is an explanatory view of a molding process according to the present invention.

FIG. 2 is a side view tool position explanatory diagram of a first step in the forming steps according to the present invention.

FIG. 3 is an explanatory diagram of material flow in a conventional method.

FIG. 4 is an explanatory diagram of material flow in the first step of the molding steps according to the present invention.

FIG. 5 shows the relationship between the radius of the tip rounded portion R of the side tool used in the first step and the maximum surface pressure of the mold (tool) applied in the first step as the maximum surface pressure level of the mold in the conventional method. It is the graph shown in comparison.

FIG. 6 is a schematic explanatory diagram of a mold device used in an experiment using lead as a material.

FIG. 7 is an explanatory view of a shape of an automobile connecting rod.

FIG. 8 is an explanatory view of a cross-sectional shape of a beam portion of an automotive connecting rod.

[Explanation of symbols]

 1 Side tool 1'Side tool 2 Material 3 Upper tool 3'Lower tool 4 Side tool 4'Side tool 5 Upper tool 5'Lower tool 6 Side tool 6'Side tool 7 Recess 7'Recess 8 Spring 9 Side tool 9'Side Tool 10 Upper tool 10 'Lower tool

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[Procedure amendment]

[Submission date] September 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

FIG. 7 is an explanatory diagram of a conventional molding process.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

FIG. 8 is an explanatory view of the shape of an automotive connecting rod.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] Figure 9

[Correction method] Added

[Correction content]

FIG. 9 is an explanatory diagram of a cross-sectional shape of a beam portion of a connecting rod for an automobile.

Claims (1)

[Claims] 1. When forming the H-shaped cross-section of a "member having an H-shaped cross-section" by forging, in the first step, a pair of "inclined flat surfaces from the R-projected center R" are formed on both sides of the material. A pair of upper and lower tools are brought close to each other with the side surface tool "having a chevron cross-section with the mold surfaces facing each other retracted in the vertical direction facing each other" and the material is reverse extruded to form the H-section web portion and the semi-formed flange portion. , In the subsequent second step, a pair of side tools with flat mold surfaces are used instead of the side tools having a chevron cross section, and the semi-finished product is pressed from both sides with the positions of the upper and lower tools fixed, thereby completing the processing. The method for forming a member having an H-shaped cross section, characterized in that the semi-formed flange portion is subjected to compression / bending while leaving a slight recess in the central portion of the outer surface of the semi-formed flange.