JPH0263627A - Manufacture of forged part - Google Patents

Abstract

PURPOSE:To prevent the generation of a crack-like groove of a forged part by casting a blank stock so that a recessed curved part is formed in the outside periphery of a gate cut remaining part, and subsequently, bringing this blank stock to plastic deformation by a die and a punch. CONSTITUTION:At the time of casting in advance a blank stock B to a prescribed shape, a recessed curved part b3 is formed in the outside periphery of a gate cut remaining part b2 which is formed, and a step difference to the end face of a blank stock body b1 is smoothened. Subsequently, this blank stock B is set to the lower die 2 of a forging device 1, forged and compressed between said die and a punch 5 being the upper die, and brought to plastic deformation. In such a way, at the time of forging, a metal of the curved part b3 of the blank stock B comes to be protruded more quickly than that of a metal of the periphery, therefore, it is prevented that a crack-like groove is generated in the part corresponding to the outside periphery of the gate cut remaining part b2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a method for manufacturing a forged product by forging a blank material cast into a predetermined shape.

(Prior art) Generally, AΩ-8i-Cu alloys, A, Q-8iCu-
Mg-based alloys have good castability and can obtain excellent strength and toughness through heat treatment, so they have been widely used as alloys for casting rocker arms and other engine parts for automobiles and other vehicles. There is. but,
Nowadays, there is a demand for higher engine output, and since the rocker arms and the like are exposed to severe conditions during operation, there is a further demand for improvements in mechanical properties such as the above-mentioned strength and toughness. Therefore, in order to meet this demand, for example,
As disclosed in Japanese Patent No. 187539, by casting a blank material using the above-mentioned Al1-8 i -Cu alloy, etc., and then forging this blank material,
Methods for improving mechanical properties are known.

(Problem to be solved by the invention) By the way, the blank material used for forging as described above is
After casting, since the weir is cut and separated from the weir for injecting the molten metal into the mold, the weir cut residue C remains protruding from the main body of the blank material a, as shown in FIG. 3(a). Then, when a blank material a having such a weir cut residue C is set in a die d of a forging device and forged, the blank material a is compressed and plastically deformed by the die d and punch e. Due to the flow of the material of blank material a due to deformation,
As shown in FIG. 3(b), there was a problem in that a crack-like groove f was generated in a portion of the forged product g corresponding to the outer periphery of the weir cut remaining portion C. This occurrence of the groove f is due to the fact that the weir cut residue C protrudes perpendicularly to the end surface of the blank main body, forming a step. This is due to the fact that the closer the object is, the faster it approaches.

The present invention has been made in view of these points, and its purpose is to specify the outer circumferential shape of the weir-cut remaining portion of a blank material to be subjected to forging, so that the shape corresponds to the outer circumference of the weir-cut remaining portion. The object is to obtain a forged product that does not have crack-like grooves in its parts.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is a method of manufacturing a forged product by forging a blank material cast into a predetermined shape. A blank material having a protruding weir cut portion is cast so that a concave rounded portion is formed on the outer periphery of the weir cut portion. Next, this blank material is compressed and plastically deformed using a die and a punch of a forging device to obtain a forged product.

(Function) With the above configuration, in the method of the present invention, the outer periphery of the weir cut remaining part protruding from the blank body of the blank material to be forged is formed with a gentle step with the end surface of the blank body due to the concave rounded part. Therefore, during forging, either the above-mentioned step is eliminated due to plastic deformation of the blank material (the flesh of the concave rounded part is pushed out due to plastic deformation of the blank material), or the flesh around it is pushed out faster. This reliably prevents the formation of crack-like grooves in a portion corresponding to the outer periphery of the weir cut remaining portion.

(Example) Hereinafter, an example of the present invention will be explained based on the drawings in Figure 1 (
Figures a) and (b) show the case of forging a rocker arm A as an engine part for a vehicle such as an automobile by the forged product manufacturing method according to the embodiment of the present invention. To explain the manufacturing procedure, first, a blank material B having a predetermined shape is cast using a casting device (not shown). As shown in enlarged detail in FIG. 2(a), on the end face of the blank wood body b1 of this blank material B, a weir for injecting molten metal into the mold after casting and a cut weir cut portion b2 protrude. has been done. Further, as a feature of the present invention, a concave radiused portion b3 is formed on the outer periphery of the weir cut remaining portion 2 of the blank body b1, and the concave radiused portion b3 forms a gentle step with the end surface of the blank body b1. has been done. The size of this concave rounded portion b3 is appropriately determined depending on the cross-sectional area and amount of protrusion of the weir cut remaining portion b2, but for example, it is preferable to set the radius of curvature to be larger than the amount of protrusion of the weir cut remaining portion b2. This has been obtained through experiments.

Next, the blank material B cast as described above is carried into the forging device 1 and set in the die 2 serving as the lower die of the forging device 1. Specifically, a support pin 4 which is biased upward by the spring force of a coil spring 3 and whose tip protrudes into the impression is retractably disposed on the die 2, and the support pin 4 and the die 2 The blank material B is supported at three points to prevent it from wobbling.

Thereafter, as shown in FIG. 1(b), the punch 5 serving as an upper mold, which is disposed above the die 2 so as to be movable up and down, is lowered, and as shown in enlarged detail in FIG. A rocker arm A is obtained by compressing and plastically deforming a blank material B using a die 2 and a punch 5. At this time, the support pin 4 is retracted against the spring force of the coil spring 3 by the downward movement of the punch 5, and its base end is brought into contact with the cylindrical member 6, so that its tip is on the same plane as the shaped part of the die 2. It is designed to be located in

Therefore, in this example, since the step between the weir-cut remaining portion b2 of the blank material body b1 and the end face of the blank material body b1 is formed gently by the concave rounded portion b3, the above step difference is caused by plastic deformation of the blank material B during forging. The direction in which the crack disappears (the protrusion of the flesh of the concave rounded part b3 due to plastic deformation of the blank material B) is faster than the direction in which the surrounding flesh protrudes, and as a result, the crack-shaped groove is formed on the outer periphery of the weir cut remaining part b2. It is possible to reliably prevent this from occurring in areas corresponding to .

Thereafter, after raising the punch 5, the rocker arm A is taken out from the forging device 1 and subjected to T under predetermined heat treatment conditions.
After performing the 6 treatments, the flash (paris) a+ formed during forging is removed using a trim die (not shown) to obtain a product.

After that, rocker arm A with this flash a1 removed
The forging process is then carried out to the shot peening process where the surface is polished and the forging process is completed.

In addition, in the above-mentioned example, the case where the forged product is a rocker arm A as an engine part for a vehicle such as an automobile is shown.
Needless to say, this is not the only option.

(Effects of the Invention) As explained above, according to the method of the present invention, a blank material having a weir cut portion protruding from the blank material body is cast so that a concave rounded portion is formed on the outer periphery of the weir cut portion. Next, this blank material is compressed and plastically deformed by the die and punch of the forging device, so that during forging, the flesh of the concave radius that bulges out due to the plastic deformation of the blank material bulges out faster than the surrounding meat. This makes it possible to reliably prevent crack-like grooves from forming in a portion corresponding to the outer periphery of the weir cut remaining portion.

[Brief explanation of the drawing]

The drawings show an embodiment of the invention, and FIGS. 1(a) and (b)
2(a) and (b) are longitudinal cross-sectional views showing the forging device before and after forging, respectively, and FIGS. 2(a) and (b) are FIGS.
) is an enlarged view of the main parts. FIGS. 3(a) and (1)) are views corresponding to FIGS. 2(a) and (b) of the conventional example, respectively. 1...Forging device, 2...Die, 5...Punch, A
...Rocker arm (forged product), B...Blank material,
bl...Blank material body, b2...Weir cutting remainder, b
3...Concave rounded part.

Claims (1)

[Claims] (1) A method of manufacturing a forged product by forging a blank material cast into a predetermined shape, the blank material having a weir cut portion protruding from the blank material body, and a concave radius formed on the outer periphery of the weir cut portion. Cast to form a part,
A method for manufacturing a forged product, characterized in that the blank is then compressed and plastically deformed using a die and a punch of a forging device to obtain a forged product.