JPS6219930B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a forging method used for processing stepped shafts as one of plastic working methods.

[Prior art and its problems]

As is well known, when forging a stepped shaft, for example, the desired final product shape may not be obtained by just one step of rolling, and in such cases, additional processing is required in the next step. Local forging is performed. Figures 1A and 1B show an example of this, in which a flange part F is formed at one end of a stepped shaft W, which is a semi-finished product, in the pre-processing process, and a flange part F is formed in the next process by so-called forward push forging.
The shaft portion S is formed by pushing in the peripheral edge of the flange portion F and extruding the center portion of the flange portion F in the same direction as the advancing direction X of the punch 1, thereby obtaining the final product shape. Note that 2 is a die and 3 is a knockout pin.

Moreover, what is shown in FIGS. 2A and 2B shows a processing method using an upsetter, in which the pre-processed part is firmly gripped, leaving a partially tapered flange part F, and the peripheral edge of the flange part F is crushed downward. This is for molding the shaft portion S.

By the way, when trying to form a multi-stage stepped shaft (product) _W1 as shown in Fig. 3, for example, rolling is a desirable processing method from the viewpoint of improving manufacturability and product accuracy. Since it is difficult to obtain the final product shape at once using only the rolling process such as the cross rolling process shown in A to E, this rolling process produces a semi-finished product W ₂ as shown in FIGS. 4E and 5.
It is a good idea to plastically deform the flange portion F of the semi-finished product W ₂ using one of the additional methods described above in the post-process to obtain the final product shape shown in FIG. 3. In other words, when rolling to the final product shape, scraps (excess material that cannot become part of the product) are generated at both ends, which requires machining in the subsequent process, which leads to a decrease in material yield. be.

Incidentally, FIG. 4 shows an example of a so-called two-piece cutting process in which the material is divided in step E to obtain two semi-finished products _W2 at the same time.

However, when trying to adopt the aforementioned forward extrusion forging method (Fig. 1 A, B) as an additional method to obtain the final product shape shown in Fig. 3, the shape of the pre-processed part of the semi-finished product is complicated. Therefore, it is impossible to insert the pre-processed parts other than the flange into the upper mold for forging, and if you try to use crush forming using the upsetters shown in Fig. 2 A and B, the shaft height (raised Since the ratio (h/d) between h and outer diameter d is less than 0.3, the amount of heaping up is insufficient and the desired final product shape cannot be obtained.

[Purpose of the invention]

An object of the present invention is to provide a forging method that can obtain a necessary and sufficient build-up amount without being constrained by the shape of the pre-processed part.

[Structure of the invention]

In the present invention, the pre-processed part of the semi-finished product excluding the flange part is gripped and restrained by a fixed mold that can be split in half, and then the flange part is The peripheral edge of the flange is pushed in, and the material at the center of the flange is pushed out in a direction opposite to the direction of movement of the punch, thereby sealing it in the closed space defined by the die and the fixed mold to form a predetermined shaft part. It is characterized by

〔Example〕

Hereinafter, more specific embodiments of the present invention will be described in detail using the drawings.

FIGS. 6A and 6B are diagrams for explaining one embodiment of the present invention. Although this semi-finished product _W2 is formed by rolling as shown in FIG. 4, detailed explanation is omitted. vinegar. Reference numeral 5 designates a hollow punch having a predetermined shaft space R formed in the inner cylindrical portion, 6 a knockout pin inserted into the punch 5, and 7 a spacer, which constitute an upper mold 8. In addition, 9a and 9b are grip inserts that also serve as dies, 10a and 10
b is an insert, and both of these constitute the lower mold 11 as a fixed mold. These grip inserts 9a, 9b and inserts 10a, 10b
are formed in half and can be opened to the left and right, and these half-shaped grip inserts 9a, 9
b and the inserts 10a, 10b firmly grip the semi-finished product _W2 , which is the raw material, as will be described later.

The lower surface of the punch 5 is tapered at an angle α in order to prevent the generation of dead metal on the pressurized surface layer of the material and to improve the swelling of the material, while the inner cylinder of the punch 5 is also tapered with the material ( A draft angle of approximately 30' is provided to improve the release of the product (product) from the mold. The angle α mentioned above is determined taking into account the amount of heaping up and other conditions, but in this embodiment it is set to 5°.

Then, the pre-processed parts of the semi-finished product W ₂ which have been pre-processed by rolling as described above, except for the flange part F, are firmly clamped with grip inserts 9a, 9b and inserts 10a, 10b, and then the punch 5 is lowered to push in the peripheral edge of the flange portion F of the semi-finished product _W2 with the lower surface of the punch 5. That is, by pushing the peripheral edge of the flange portion F in a direction that reduces its thickness, a portion of the peripheral edge portion is moved toward the center, and further, as the punch 5 descends, the thickness of the flange center portion is pushed toward the center. It is pushed up in the opposite direction to the direction of movement of 5 and swells.

When the punch 5 reaches the bottom dead center, the material meat that has been heaped up as described above is transferred to the punch 5, the knockout pin 6, and the grip inserts 9a, 9.
The shaft portion S is formed into a predetermined shape by filling the shaft space R closed by the inserts 10a and 10b.

After the molding is completed, the punch 5 is raised while pushing down the knockout pin 6, and the grip inserts 9a, 9b and the inserts 10a, 10b are opened left and right to take out the final product _W1 .

In other words, according to the above embodiment, by holding the pre-processed part of the semi-finished product with a fixed die and performing closed backward extrusion forging, the heap height h and the flange part F can be adjusted as shown in FIG. This means that the ratio (h/d) to the outer diameter d can be improved by more than three times that of the conventional method.

Here, when selecting the material diameter, that is, the diameter of the flange portion at the semi-finished product stage, the following points should be considered.
First, if a material with a diameter that is significantly smaller than the diameter of the flange part in the final product stage is used, the meat will flow in the radial direction and the meat will not bulge in the axial direction.
Extra thickness called a standing beam tends to occur on the extruded side of the outer periphery of the flange, or insufficient thickness is likely to occur at the corner of the extruded shaft. On the other hand, when using a material with a diameter equivalent to the diameter of the flange part in the final product stage, there is a strong flow of flesh in the axial direction, so although the above-mentioned standing burrs and missing parts are less likely to occur, the outer peripheral surface of the flange part Sink marks are likely to occur.
Therefore, considering the best balance between stand-up, underfill, and sink, it is desirable to select a material diameter that is 93 to 95% of the diameter of the flange portion in the final product stage.

〔Effect of the invention〕

As explained in detail above, according to the present invention, the pre-processed part of a pre-processed semi-finished product is gripped by a fixed die that can be split in half, and the raw material is pushed out in the opposite direction to the advancing direction of the die. By using closed rear extrusion forging, local extrusion forging can be performed as an additional process without being affected by the shape of the pre-processed semi-finished product, and the amount of material build-up is more than three times that of conventional methods. can be done. Furthermore, if rolling is performed as a pre-processing, complex shaft products can be manufactured in a short time with a high yield.

[Brief explanation of the drawing]

Figures 1A and B are explanatory diagrams for explaining the conventional forward extrusion forging method, Figures 2A and B are explanatory diagrams for explaining the conventional crush forming using an upsetter, and Figure 3 is an explanatory diagram for explaining the stage of the product. An explanatory diagram showing an example of an attached shaft, Fig. 4 is an explanatory diagram to explain the rolling process as a pre-processing, Fig. 5 is an explanatory diagram of a semi-finished product, and Figs. 6 A and B are one embodiment of the present invention. FIG. 3 is a cross-sectional explanatory diagram for explaining an example. 5... Punch, 9a, 9b... Grip insert, 11... Lower die (fixed type), W ₁ ... Product (stepped shaft), W ₂ ... Semi-finished product, F... Flange part, S... Shaft part,
R...Axis space part.

Claims (1)

[Claims] 1. A method in which a flange portion is formed in advance on a part of a pre-processed semi-finished product, and the flange portion is crushed in a subsequent process to form a shaft portion by forging, wherein the half-finished product excluding the flange portion is The pre-processed part of the product is gripped and restrained by a fixed die that can be split in half, and then the peripheral edge of the flange is pushed in using a punch with a predetermined axial space formed in the inner cylinder. A method for forging a shaft, characterized in that a predetermined shaft portion is formed by extruding the material at the center in a direction opposite to the advancing direction of a punch and sealing it in a closed space defined by a die and a fixed die. 2. The method for forging a shaft according to claim 1, wherein the pre-processing is a rolling process.