JPH0760392A - Method for forging parts having arm part - Google Patents

Abstract

PURPOSE:To increase the mechanical strength of forged articles obtd. with decreased flashes, high yield and easy operation even if these articles are parts of intricate shapes (steering knuckles, crank shafts, etc.) consisting of cup-shaped head parts having various projecting parts and curved or flexed arm parts. CONSTITUTION:The head parts 8 are molded by closed forging from a blank cut and heated by using dies 1, 2, having a blank extrusion port 3 of an approximately arm part shape directed in the outlet direction toward the front end of the arm parts and inner punches 5, 6 in the method for forging the parts consisting of the head parts and the bent arm parts extending from the head parts. The roughly shaped arm parts 9 are extruded form the blank extrusion port 3 and the arm parts are forged by open dies from the roughly shaped arm parts 9, by which the parts are molded to into specified shapes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forging a component having an arm portion, and more particularly to a method for forging a component comprising a head portion such as a steering knuckle or a crankshaft and a bent arm portion.

[0002]

2. Description of the Related Art Manufacturing of components such as a steering knuckle, which comprises a head portion and an arm portion having a bent portion such as an offset bend extending from the head portion, is usually carried out by forging. Roll process-forming process-core deburring process-outside It is carried out through a series of steps including a deburring process. Of these, in the first roll step, since the shape of the crude material obtained by roll forging is usually straight, although there is no problem in the case of a part in which the arm portion to be forged is straight, offset bending, etc. For forming an arm portion having a bent portion, it is necessary to make the roll diameter of the rough material obtained after the rolling step larger than the diameter of the target arm portion, and the yield is very low. In order to overcome this, it is possible to bend the arm part after the rolling process, but it is difficult to bend it accurately according to the impression shape of the forging die, and if the forming press is equipped with an automatic transporter, it is further difficult. Difficult and impractical.
Further, the above-mentioned forming process is performed in a few steps using an open forging die, but as shown in FIG. 6, the impressions 18, 1 of the head part and the arm part of the forged part are respectively formed.
Mold 1 with impression 20 with 9 integrated
6 and 17, the head portion and the arm portion are simultaneously molded. Since the roll-forged rough shape material used for this molding is considerably larger than the product shape after molding, before the outflow of the material to the outer burr in the flash land part is suppressed, that is, the interval between the flash land parts is large. In the meantime, a large amount of material flows out to the outer burr part, and as a result, the burr 22 becomes very large in the molded part 21 as shown in FIG.
Yield decreases. For example, the yield in the case of forming a steering knuckle having a shape as shown in FIG. 7 from a solid round bar-shaped steel material was 40 to 50%, which was considerably low.
Moreover, since the cup-shaped head portion has various convex portions and has a complicated shape, it takes a lot of time and effort to remove burrs around the head portion, resulting in a decrease in productivity.

On the other hand, as a forging method for reducing the burr of molded parts and improving the yield, Japanese Patent Laid-Open No. 55-922 has been proposed.
Japanese Patent Laid-Open No. 45-45 discloses a method for forging a part having a shaft portion and a flange portion at its end, in which the shaft portion is formed by closing forging to form the shaft portion, and then the flange portion is formed by closing forging. There is. However, the method of the publication is effective for a part having a shape in which a shaft portion extends straight from a flange, but cannot be directly applied to forging a part having a bent arm portion.

Further, in Japanese Patent Laid-Open No. 166842/1989, forging waste having a plurality of radial branches is formed by closed forging and then finished by deburring forging. A forging method is disclosed. As described above, according to this method, the preform formed by the closed forging is further subjected to the flash forging. However, although the method of the publication can be applied to the production of a flat article such as a forged product with radial branches, it cannot be applied as it is to the forging of a part having a head part and a bent arm part, and the head part is not applicable. And, the more complicated the shape of the arm portion, the lower the availability of the method of the above publication.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of such a situation, and has a component including a head portion and a bent arm portion extending from the head portion, particularly a cup-shaped head portion. Even for parts with complicated shapes consisting of curved or bent arms, parts with low burr, high yield, easy operation, and without impairing the mechanical strength of the obtained forged product. It is an object to provide a forging method.

[0006]

That is, the present invention is a method for forging a component including a head portion and a bent arm portion extending from the head portion, and a material in which an outlet direction is directed to the tip of the arm portion. The head part is formed by closed forging using a die having an extrusion port, and the material is extruded from the material extrusion port to form a rough arm part, and then the rough arm part of this molding material is forged with an open die. The present invention relates to a method for forging a component having an arm portion, which is characterized by being formed into a predetermined shape.

In the forging method of the present invention, the head portion of the component is molded using not only the impression of the head portion itself but also a die having a material extrusion port whose outlet direction is directed to the tip of the arm portion of the component. Be seen. At the time of molding the head portion, the material is extruded from the material extruding port to form the rough arm portion at the same time. However, the head portion is surely formed and then the rough arm portion is extruded. As described above, it is preferable to prevent the molding material from entering the material extrusion opening too early, for example, by providing a bent portion or the like at the entrance of the material extrusion opening. An inner punch may be used depending on the desired shape of the head portion of the component. The shape of the head is not particularly limited as long as it can be closed and forged, but various shapes such as lumps or plates, cups or H-shaped cross-sections, various mounting parts in addition to the above shapes, etc. The present invention can be applied to those having uneven portions and other complicated shapes. This step is performed by closed forging, and burrs do not come out, so even in the case of a part having a complicatedly shaped head part that was difficult to deburr in the case of conventional open type forging, No deburring operation is required, contributing to improved productivity.

Since the die used in the closed forging is provided with a material extruding port whose outlet direction is directed to the tip of the arm portion, at the time of closed forging, a part of the material is ejected from the extruding port to the arm portion. It is extruded to the approximate shape (coarse arm part). As a result, the open die forging of the arm portion following the forming of the head portion by the closed forging is more easily performed, and the burrs that occur are even on the left and right and can be extremely reduced. Therefore, in the present invention, it is preferable that the material extrusion port of the die is set so that the overall shape thereof substantially corresponds to the shape of the arm portion of the component.

In the present specification, the "bent arm portion extending from the head portion" means that the axis line of the connecting portion of the arm portion to the head portion is deviated from the axis line of the other arm portion, for example, Both axes are offset in parallel, that is, a so-called offset bend is present, a plurality of axes are offset in the arm portion, an arm that is curved in a bow shape as a whole, or an arm that has at least one bending portion. In addition, it means an arm or the like having both the above-mentioned axis shift and the curved portion.

In the forging method of the present invention, the open die used for forming the arm portion may have an opening corresponding to the head portion as long as it has an impression of the arm portion, but the arm portion may be opened. In order to prevent the parts from bending during molding, it is preferable to have a structure for pressing the head portion. Further, the structure for pressing the head portion may be separated from the arm portion forming die.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, but the present invention is not limited to this embodiment. 1 to 5 show an example of manufacturing a steering knuckle according to the forging method of the present invention. The steps will be described below in order. First, as shown in FIG. 1, the molding of the head portion and the rough arm portion is performed by inserting the die into a shape having only one material extrusion port 3 when the upper and lower dies 1 and 2 are closed. Then, the upper and lower inner punches 5 and 6 for imparting a cup shape to the head portion are used. A solid cylindrical steel material 7 having a predetermined volume cut into a predetermined length is heated to an appropriate temperature, and the material 7 is placed vertically. After closing with the dies 1 and 2, the inner punches 5 and 6 are inserted into the upper surface and the lower surface of the material 7, respectively, so that the head portion of the component is closed and forged, and at the same time, the rough arm portion is pushed out from the material extrusion port 3. . The impression portion of the dice 1 and 2 is provided with a concave portion 4 which forms a convex portion of the head portion.
The material extruding port 3 provided at the arm portion joint portion 2 has an outlet directed toward the tip end portion of the arm portion, and the shape is approximately equivalent to the arm portion, and the material extruding port 3 is formed from the arm portion joint portion on the side surface of the head portion. The structure is inclined downward toward the exit. FIG. 2 is a cross-sectional view showing a state after the head portion 8 is closed and forged as shown in FIG. 1 and at the same time the rough arm portion 9 is extruded from the material extrusion port 3. Further, FIG. 3 is a plan view showing the same state as FIG. 2 except for the die 1 and the inner punch 5. No burr is generated on the outer circumference of the head portion 8, and the rough arm portion 9 is bent so that the rough arm portion 9 can be easily molded into a curved arm portion later, and its tip is directed to the tip of the arm portion after molding. .

The thus-obtained rough component including the head portion 8 and the rough arm portion 9 is die-forged by the open dies 10 and 11 as shown in FIG. The open type 10,1
1 has an impression 12 to be molded in the arm portion, and the portion corresponding to the head portion 8 is completely opened, but the head portion 8 is held down at only one position of each open mold 10, 11, Prevents bending of parts during forging. The part 14 after forging with the open molds 10 and 11 is shown in FIG.
As shown in the drawing, there is no burr around the cup-shaped head portion 8 as shown in the figure, and the burr generated on the curved arm portion 13 is extremely small, and the burr is substantially even on the left and right sides. For this reason, the component 14 was then subjected to the core deburring and outer deburring steps, which were very easy and completed in a short time. The yield of the component (steering knuckle) 14 obtained as described above is 75 to 85.
% Was extremely high. Further, although the component 14 obtained as described above has a shape in which a curved arm portion extends from a head portion having a considerably complicated shape, an excessive force is not applied during molding. Therefore, it has sufficient mechanical strength and can be used as a steering knuckle with a high load. On the other hand, in the case of the conventional forging method using the open die in which the impression of the head portion and the arm portion are integrated, the yield is 40 to 50% as described above, which is considerably lower than the method of the present invention.

[0013]

As described above in detail, in the method for forging a component having an arm portion according to the present invention, the head portion is formed by closed forging, the rough arm portion is extruded, and then the rough shape is formed. Since the arm part bent from the arm part is formed by open die forging, burrs do not occur on the outer periphery of the head part, the burrs that occur on the arm part are extremely small, and even on the left and right, the forging yield It is high and the deburring work is very easy. Also, since the arm part is molded from the rough arm part that is extruded toward the tip direction, it is very easily and accurately performed, and the mechanical part is joined at the bent part and the head part. The strength does not decrease. Therefore, according to the forging method of the present invention, it is possible to obtain a component having a complicated shape having a bent arm portion with high yield and high mechanical strength. As described above, the present invention accurately manufactures various parts such as a steering knuckle, a crankshaft, a suspension arm, and the like, which are required to have high mechanical strength, including a head part and a bent arm part, with high yield and easy operation. To be able to do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state before forming a head portion of a component in a closed forging die according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing molding of a head portion and extrusion of a rough arm portion of a component in the closed forging die shown in FIG.

FIG. 3 is a plan view showing a state after molding of a head portion of a component and extrusion of a rough arm portion in the closed forging die shown in FIG. 2 with an upper die and an inner punch removed.

FIG. 4 is a cross-sectional view showing molding of an arm portion of an open-type component according to an embodiment of the present invention.

5 is a plan view of the forged component obtained after the molding shown in FIG.

FIG. 6 is a sectional view of a forging die used in a conventional forging method of a steering knuckle.

FIG. 7 is a plan view of a steering knuckle obtained by the conventional method shown in FIG.

[Explanation of symbols]

 1, 2 dies 3 material extrusion port 4 head convex portion forming die recessed portion 5, 6 inner punch 7 material 8 head portion 9 rough arm portion 10, 11 open type 12 open type impression 13 arm portion 14 forged part 15 burr

Claims (1)

[Claims] 1. A method for forging a component including a head portion and a bent arm portion extending from the head portion, wherein the head is formed by using a die having a material extrusion port whose outlet direction is directed to the tip of the arm portion. Characterized in that the portion is formed by closed forging and the raw material is extruded from the raw material extrusion port to form a coarse arm portion, and then the coarse arm portion of this forming material is forged by an open die to be formed into a predetermined shape. Forging a component having an arm portion.