JPS59199142A - Cold forging method of hollow cylindrical body - Google Patents

Abstract

PURPOSE:To form a forward drawn or straight central hole to a cylindrical body in cold forging the hole part to said body by forming the projecting part at the top end of a molding formed by extrusion into the forward divergent shape having a central mandrel and drawing the outside diameter of the projecting part by a knocking out process. CONSTITUTION:A pin 20A for punching and extrusion is moved upward to form a projecting central hole body 42 at the same instant when a blank material M is inserted into a die 10 and an extruding punch 50 is forced therein. The projecting part 11 of the die 10 is forward divergent. When a ring ejector 30 is knocked out by retreating the pin 20A, a forward divergent part 42 is drawn straight and a fine hole 41a is made into the forward drawn hole. If the pin 20A is tapered, the hole 41a is made straight. The forward drawn fine hole and straight deep hole which are impossible to be worked by cold forging are easily forged by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold forging method for a hollow cylindrical body, and more specifically, the outer shape of the front convex part of the hollow cylindrical body is a straight cylindrical shape, and the inner shape of the hole in the front convex part is a front drawing ( The inner diameter of the front end is smaller than the inner diameter of the rear end) or a thin large stray! -Relates to a method for mass producing hollow cylindrical bodies by cold forging.

As a conventional cold forging method for hollow cylindrical bodies, for example, Japanese Patent Application No. 56-47604 (Japanese Unexamined Patent Publication No. 57-16
No. 0543) There is an invention. The outer shape of the front convex portion of the hollow cylindrical body formed by this method is a front convex shape, and a straight through hole is bored in this convex portion. Therefore, with this method, it is impossible to form a hollow cylindrical body whose outer shape is a straight cylinder and whose front convex part has a straight cylindrical shape and the inner shape of the hole in this convex part is a front drawing or a narrow straight hole, only by cold forging. be.

This invention provides a hollow cylindrical body that can be easily formed, in which the outer shape of the front convex part of the hollow cylindrical body is a straight cylindrical shape, and the internal shape of the hole in the front convex part is a front drawing or a narrow straight shape. The purpose is to provide a cold forging method.

Further, the gist of the present invention is to form the outer shape of the front convex part of the hollow cylindrical body into a wide-forward shape by extrusion processing, and at the same time, drill a straight or front-wide hole in the front convex part. The outer shape is formed into a straight cylindrical shape, and at the same time the inner shape of the hole is formed into a forward drawing or a narrow straight hole.

Hereinafter, an explanation will be given based on FIGS. 1 to 4 showing embodiments of this invention method.

(First embodiment) In FIGS. 1 and 2, the outer shape of the front convex part 42 formed in the hollow cylinder 40 is a straight columnar shape, and the inner shape of the hole 41a formed in the front convex part 42 is a front aperture. The cold forging process of the hollow cylindrical body 40 (which has an inverted truncated conical shape when viewed from the front of the convex portion 42) is shown in FIG. 1 when the forming of the hollow cylindrical body 40 is completed, and FIG. The state in which the body 40 is being ejected from the mold 10 is shown.

(Cold forging method) (1) Immediately after placing the material M in the mold lO, the extrusion punch 5
0 is lowered to pressurize the material M from above, and at the same time, the material M is perforated and extruded by the perforation extrusion pin 20A to perform composite extrusion processing.

(2) At this time, the outer diameter of the hollow cylinder 40 expands forward due to the truncated conical convex molding part 11 formed in the center of the mold 10 (the outer diameter of the front end is the outer diameter of the rear end). A front convex portion 42 with a straight hole bored inside is formed (see FIG. 1).

(3) When the ring ejector 30 is raised to eject the hollow cylindrical body 40 out of the mold 10 after completion of molding, the front convex portion 42
Since the outer diameter of the front end portion 42 of the front end portion 42 is reduced (squeezed) by the rear end portion 11A of the convex portion molding portion 11, the outer shape of the front convex portion 42 is a straight cylindrical shape with the same diameter as the diameter of the rear end portion 11A. The inner shape of the hole of equal diameter formed by the punching push-out pin 20A is formed into the front drawing hole 41a (see FIG. 2).

(Second Embodiment) In Figures 3 and 4, the outer shape of the front protrusion 42 formed in the hollow cylinder 4o is a straight columnar shape, and the inner shape of the hole 41b formed in the front protrusion 42 is a narrow hole. Straight hollow cylindrical body 4
0 cold forging process is shown.

FIG. 3 shows the hollow cylindrical body 40 when the molding is completed, and FIG. 4 shows the hollow cylindrical body 40 that has been molded and is being discharged from the mold 10.

The cold forging method in this case is the same as in the first embodiment, with the only difference being that the perforated portion of the perforated push-out pin 20B is tapered (truncated conical).

(Cold forging method) (1) The material M is subjected to composite extrusion processing in the same manner as in the first embodiment.

(2) At this time, due to the truncated conical convex molding part 11 formed in the center of the mold 10, the outer shape of the hollow cylinder 40 expands forward, and a hole similar to this expands forward. A front convex portion 42 having a hole therein is formed (see FIG. 3).

(3) When the ring ejector 30 is raised to eject the hollow cylindrical body 40 out of the mold 10 after completion of molding, the front convex portion 42
Since the outer shape of the front end portion 42b of the front end portion 42b is reduced (squeezed) by the rear end portion 11A of the convex portion molding portion 11, the outer shape of the front convex portion 42 becomes a straight cylindrical shape with the same diameter as the diameter of the rear step portion 11A. As a result, the inner shape of the drilled front widening hole is formed into a straight hole 41b (see FIG. 4).

Note that this cold forging method can be used for extrusion processes other than composite extrusion processes, and can also be used for forming articles other than hollow cylinders.

As described above, the method of the present invention uses only the extrusion process using an extrusion punch and a punching extrusion pin and the ejection process of the processed product using a ring ejector. This has the effect that it is possible to cold forge a hollow cylindrical body that is forward drawn or straight.

When making a hollow cylindrical body in which the outer shape of the front convex part is cylindrical and the inner shape of the hole in the front convex part is a front diaphragm using the conventional method, for example, the outer shape of the front convex part and the inner shape of the hole formed in this convex part are In both cases, a large number of man-hours were required to cold-forge the front drawing and then to form the outer shape of the front convex part into a straight cylindrical shape by cutting, but the method of this invention significantly reduces the number of man-hours and can be easily mass-produced. It is possible to do so.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing cold forging in the first embodiment of the method of the present invention, and FIGS. 3 and 4 show cold forging in the second embodiment of the method of the present invention. It is a schematic diagram. 41a... Front aperture hole, 41b... Straight hole, 42... Front convex portion. Patent applicant

Claims (1)

[Claims] By extrusion processing, the outer shape of the front convex part of the hollow cylindrical body is formed into a shape that spreads forward, and at the same time, a straight or wide hole is bored in the front convex part, and then the outer shape of the front convex part is made into a straight cylindrical shape. A method for cold forging a hollow cylindrical body, characterized by forming the inner shape of the hole into a forward drawing or a straight shape at the same time as forming.