JP2002239679A - Method for forge-forming cylindrical shaft material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forge-forming a cylindrical shaft material with which high productivity is attained and service life of a punch can be extended. SOLUTION: This method is constituted of a forging process, in which a solid intermediate formed product having the whole length at shorter than that of the desired cylindrical shaft material, is formed from a cylindrical solid blank, and a pierce forming process, in which pushing-out is performed with the punch in the forging apparatus from one end part of the intermediate formed product and simultaneously, the forged thickness is pushed out to the other end part side and the desirable outer shape and through-hole are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging method for forming a cylindrical shaft having a through hole penetrating in the axial direction.

[0002]

2. Description of the Related Art Conventionally, when a cylindrical shaft is formed, as shown in FIG. 8, a cylindrical solid material W100 (FIG. 8A) is subjected to forging multiple times to obtain a desired cylindrical shaft. An intermediate molded product W101 (FIG. 8 (A)) having substantially the same outer shape as W102 (FIG. 8 (C)) is formed, and then the center of the intermediate molded product W101 near the center is restrained with the outer periphery thereof constrained. Through hole 10 of cylindrical shaft object W102 desired by punch
A molding distance t equal to the distance in the seven axial directions was punched out to form the cylindrical shaft W102.

[0003]

When the cylindrical shaft W102 is formed by the forging method as described above, the cylindrical shaft W102 can be formed in a small number of steps, and there is an advantage that the productivity is improved.

However, an intermediate molded product W10 as shown in FIG.
When the cylindrical shaft W102 is formed from No. 1, the punching load applied to the punch increases in proportion to the distance of the shaft having a long pushing distance, and the life of the punch may be shortened. Therefore, when the shaft is pushed out, it may be pushed out a plurality of times, but there is a problem that the number of steps is increased.

[0005] Further, after forming the intermediate molded product W101, a through hole 107 may be formed by a drill. However, in the drill forming, it takes more time than in the punching, so that the productivity may be reduced.

Accordingly, the present invention solves the above-mentioned problems,
An object of the present invention is to provide a method of forging a cylindrical shaft having high productivity and capable of extending the life of a punch.

[0007]

The method of forging a cylindrical shaft according to the present invention is as follows.

[0008] A forging process of forming a solid intermediate molded product having a shorter overall length than a desired cylindrical shaft from a cylindrical solid material, and punching out one end of the intermediate molded product with a punch of a forging device. At the same time, a piercing process for extruding the forged meat toward the other end and forming a desired outer shape and a through hole is performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1C is provided with a through-hole 7 near the center in the axial direction, a cylindrical body 8 extending in a cylindrical shape near the center in the axial direction, and a flange projecting circumferentially outward on one end at one end. A cylindrical shaft W2 that forms a small-diameter extending part 6 smaller in diameter than the cylindrical main body 8 at the other end of the part 3. The step of forming the cylindrical shaft W2 will be described with reference to FIG. First, (A) of FIG.
A cylindrical solid material W0 as shown in FIG. 1 is pressed in the axial direction to form a concave portion 4 which is concave in the axial direction at one end, and a flange 3 of a desired cylindrical shaft W2 is formed on the outer peripheral side at one end. Is formed, and an intermediate molded product W1 which is continuous with the flange portion 3 and is formed by molding a cylindrical main body 5 having the same shape as the outer periphery of the cylindrical main body 8 of the cylindrical shaft W2.

Next, a piercing process for forming a hollow cylindrical shaft W2 from the solid intermediate molded product W1 will be described.

FIG. 2 shows the forging device 11 in a state before the molding in which the intermediate molded product W1 is arranged. Reference numeral 31 denotes a lower die, which is a forming die 32 defining a die-forming space 33 in which the intermediate molded product W1 is arranged.
And a die holder 34 for holding the forming die 32,
The ring-shaped holding plate 35 is formed by the forming die 32 and the die holder 3.
4 and is fixed to the holding plate 35 with bolts 36 so that they are integrally assembled. Here, the forming die 32 has a first inner peripheral portion 32a having the same shape as the outer periphery of the cylindrical main body 8 of the desired cylindrical shaft W2 and a first inner peripheral portion 32a having the same shape as the outer periphery of the small-diameter extending portion 6 from the punch 22 side described later. A second inner peripheral portion 32b and a discharge inner peripheral portion 32c into which the punch 22 is inserted are formed. Reference numeral 37 denotes a stopper which is engaged with a column 38 provided on the upper surface of the die holder 34, is disposed on the upper end side of the column 38 by the restoring force of a contracted spring 40, and is positioned by a stopper 39 fixed to the column 38. You. An upper die 21 has the same outer diameter as the through-hole 7 of the cylindrical shaft W2, and holds a punch 22 that can be inserted into the discharge inner peripheral portion 32c of the lower die 31 and a lower die side of the punch 22. A punch 22 and a punch holder 23.
Is fixed integrally with a ring-shaped upper guide 24 to a vertically movable upper base 25 with bolts 26.

When a cylindrical shaft W2 is formed from the intermediate molded product W1 by the forging device 11, first, as shown in FIGS. 2 and 4, the cylindrical main body W1 is positioned with the flange 3 of the intermediate molded product W1 positioned upward. 5 is the first inner peripheral portion 3 of the forming die 32 of the lower die 31
The intermediate molded product W <b> 1 is put into the molding space 33 of the lower die 31 so as to engage with 2 a. After that, the upper mold 21 is lowered,
Extrusion and punching by the punch 22 are started, and the processing state will be described with reference to FIGS.

First, as shown in FIG. 5, the intermediate molded product W1 is pressed from above by the punch 22, and the forged meat in the area facing the tip end face of the punch 22 is extruded downward.
The flow to the space defined by the second inner peripheral portion 32b of the second 2 starts. When the punch 22 further descends, as shown in FIG. 6, the through hole 7 is formed up to the cylindrical main body 5 of the intermediate molded product W1, and the punch 22 is extruded almost all over the space defined by the second inner peripheral portion 32b. Is filled with forged meat,
Thereafter, when the punch 22 further descends, the space defined by the second inner peripheral portion 32b is completely filled with the forged meat, and the punch 22 pushes out the filled portion, and as shown in FIG. The formed small-diameter extension 6 is formed, and the formation of the cylindrical shaft W2 is completed.

The upper die 21 is moved downward while the stopper 3
When the push-out is completed, the spring 40 is contracted by the lowering of the stopper 37 at the time when the pushing-out is completed, as shown in FIG. The contraction of the spring 40 is for applying an urging force for returning the stopper 37 to the initial position as the upper mold 21 rises. In addition, the stopper 37 is arranged to restrict the rise of the cylindrical shaft W2 and remove the cylindrical shaft W2 from the punch 22 when the formed cylindrical shaft W2 adheres to the punch 22 and rises.

As described above, according to the forging method of the cylindrical shaft W2, a forging step of forming a solid intermediate molded product W1 having a shorter overall length than the desired cylindrical shaft W2 from the cylindrical solid material W0. And a piercing process for extruding forged meat from the one end of the intermediate molded product W1 with the punch 22 of the forging device 11 to the other end and simultaneously forming the desired outer shape and the through hole 7. Therefore, the forming distance T1 of the punching in the initial stage of the punching is short, and the amount of the punching is small, so that the punching load applied to the punch 22 can be reduced. The hole 7 can be formed.
Further, the through-hole 7 can be formed by a single operation without dividing the punching operation into a plurality of operations.

[0017]

As described above, according to the method for forging a cylindrical shaft according to the present invention, a forging process for forming a solid intermediate molded product having a shorter overall length than a desired cylindrical shaft from a cylindrical solid material. And, because it consists of a pierce forming step of extruding the forged meat to the other end side while simultaneously punching out from one end of the intermediate molded product with a punch of a forging device, and forming a desired outer shape and through hole, Since the forming distance of the punching at the initial stage of the punching is short and the punching amount is small, the punching load applied to the punch can be reduced, and the life of the punch can be extended. Further, since the punching is completed by a single molding, the productivity can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional plan view showing a forging process of a cylindrical shaft according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional plan view showing a state before forging forming for forming a cylindrical shaft from an intermediate molded product according to an embodiment of the present invention.

FIG. 3 is a partial cross-sectional plan view showing a state after forging of a cylindrical shaft formed from an intermediate product according to an embodiment of the present invention.

FIG. 4 is an enlarged view of a portion A in FIG. 2;

FIG. 5 is a cross-sectional plan view illustrating a first stage of a forging process of forming a cylindrical shaft from an intermediate product according to an embodiment of the present invention.

FIG. 6 is a cross-sectional plan view showing a second stage of a forging process of forming a cylindrical shaft from an intermediate product according to an embodiment of the present invention.

FIG. 7 is a cross-sectional plan view illustrating a third stage of a forging process of forming a cylindrical shaft from an intermediate product according to an embodiment of the present invention.

FIG. 8 is a cross-sectional plan view showing a conventional forging process of a cylindrical shaft.

[Explanation of symbols]

 7 Through-hole 11 Forging device 22 Punch W0 Solid material W1 Intermediate molded product W2 Cylindrical shaft

Claims (1)

[Claims] 1. A forging step of forming a solid intermediate molded product (W1) having a shorter overall length than a desired cylindrical shaft (W2) from a cylindrical solid material (W0), and the intermediate molded product (W1).
Of the forging device (11) with the punch (22) of the forging device (11), and at the same time, extrude the forged meat to the other end.
A forging method for a cylindrical shaft, comprising a piercing step of forming a desired outer shape and a through hole (7).