JPS5853128Y2 - mold - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mold for forming, by plastic deformation, a protruding ridge portion such as a torsion spline or a helical gear having a loose twist on its curved surface.

For spline shafts, gears, etc., in order to prevent fitting or meshing with other parts, the protrusions such as the toothed parts should be twisted loosely with respect to the axis. many.

Such a spline shaft with twisted protrusions can be obtained, for example, by press-fitting a material to be formed into a mold having torsion protrusions on the curved surface and plastically deforming the curved surface. It was difficult to form stripes, and it was not possible to obtain a strip with high precision.

In addition, with repeated use, the left and right sides of the protruding part of the mold, which determines dimensional accuracy and amount of twist, will wear out, but this wear cannot be corrected later, and it is not suitable for long-term use. I couldn't stand it at all.

The present invention provides a mold that eliminates the above-mentioned drawbacks, and the projecting strips provided on the peripheral surface of the mold are extended parallel to the direction in which the material to be molded is introduced without being twisted. It is characterized in that a torsional force is applied to the material to be formed by the tip end surface of the strip.

The present invention will be described below with reference to illustrated embodiments in which the present invention is applied to a mold for forming twisted splines on the outer peripheral surface of a material to be molded.

In FIG. 1, reference numeral 1 denotes an extrusion mold as a mold, and a plurality of protrusions 3.degree. 3.. are provided on the circumferential surface of an extrusion hole 2 extending in the vertical direction.

These protrusions 3 are arranged at predetermined intervals in the circumferential direction of the extrusion hole 2, and each protrusion 5, that is, both side surfaces 3a thereof.
, 3a extend parallel to the axis of the extrusion hole 2.

As shown in FIG. 2, each protrusion portion 3 has a tip end surface (upper end surface) composed of three surfaces: left and right inclined surfaces 3 b t 3 c and a middle surface 3 d, and the left and right inclined surfaces 3 b t 3
c is a tapered surface that is inclined rearward toward the side surface 3a, and the middle surface 3d is a horizontal surface.

This middle surface 3d is offset to the right by δ with respect to the center line l of the protrusion 3, and the left and right inclined surfaces 3b, 3
The inclination angles of c are different angles that form α and β (α>β) with respect to the horizontal plane.

In the embodiment, a material to be formed 4 as shown in FIG. 3 is forcibly pushed into the extrusion hole 2 from above.

When the material to be formed 4 passes through the protrusion 3, it is subjected to different resistance forces due to the left and right inclined surfaces 3b*3c of its upper end surface, so the material to be formed 4 is subjected to torsional force. Become.

Due to the plastic deformation accompanied by such torsional force, the outer circumferential surface of the material to be formed 4 after forming has protrusions 4a, 4a, 4a, 4a, 4a, 4b, etc. as splines with loose twists as shown in FIGS. 4 and 5.・
・ will be formed by the number of times corresponding to the protrusion portion 3.

Here, the amount of twist of the protruding portion 4a of the material to be formed 4 increases as the offset amount δ increases and the angle difference α-β increases.

Note that, since the torsional force due to the above-mentioned torsional deformation acts on the left and right side surfaces 3a, 3a of each protruding strip 3, it is necessary to prevent the torsional deformation of the material to be formed 4 from being hindered, and also to prevent the extrusion mold of the material to be formed 4. 1, it is desirable to keep the length of each protrusion 3 as short as possible.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

(2) The left and right inclined surfaces 3 b and 3 c may directly intersect to form a ridgeline, without providing a particular horizontal surface 3 d on the upper end surface of the protrusion 3 .

■ It can be applied not only to splines but also to all cases where twisted protrusions are formed, such as the teeth of helical gears.

■ It can also be applied to forming twisted protrusions on the inner circumferential surface of a material to be formed, such as the inner circumferential surface of the boss portion of a gear.

Of course, in this case, the protruding stripes 3 are provided on the outer periphery of the mold.

■ It can be applied not only to extrusion molds but also to all molds that plastically modify the material to be formed using a fitting means.

■ When molding the outer peripheral surface of the material to be molded, the material to be molded may be hollow.

As described above, in the present invention, since the protruding part of the mold is linear without twisting, the protruding part can be easily finished with high precision, and the forming precision of the material to be formed can be improved. .

In addition, even if the end face of the protrusion that determines the amount of twist wears out, it can be easily reused by re-polishing the end face or by replacing only the end face part with a new end face part that has been separately machined. Since it can be used, it can be used for a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of the present invention, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is an external view showing the state of the material to be formed before forming, and Fig. 4 is FIG. 5 is an external view showing the state of the molded material after molding, and FIG. 5 is a cross-sectional view taken along the line -V in FIG. 1...Extrusion die (molding die), 3...Protrusion portion, 3 b t 3 c... Inclined surface, 4...
...Material to be formed.

Claims (1)

[Scope of utility model registration request] In a molding die in which a protrusion protrudes from the circumferential surface and the torsion protrusion is plastically worked on the circumferential surface of the material to be formed by forcibly fitting the material to be formed, The protrusion is extended parallel to the fitting direction of the material to be formed, and two left and right inclined surfaces are formed on the tip end surface of the protrusion of the mold, each of which gradually recedes toward the side surface of the protrusion. A mold characterized in that the shapes of the two inclined surfaces are asymmetrical.