JPH0562012B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a forging method for cylindrical parts, in particular, a forging process for cylindrical parts, in particular a method in which the central part in the longitudinal direction is the thickest part, and the inner circumferential surfaces on both ends are tapered surfaces. This relates to a forging method for cylindrical parts.

(Prior Art) Generally, a cylindrical part (hereinafter referred to as a "tapered inner cylindrical part") in which the central part in the longitudinal direction is the thickest part and the inner circumferential surfaces on both ends are tapered surfaces is used, for example, in the piston pin of an engine. It is used.

Conventionally, as an example of a manufacturing method for the tapered inner cylindrical component, a cylindrical material having a uniform inner diameter and outer diameter is formed by casting, forging, etc., and the inner periphery of this cylindrical material is tapered at both ends. The cylindrical part was formed by cutting so as to expand.

(Problems to be Solved by the Invention) However, according to the above conventional manufacturing method of cylindrical parts, the inner circumferential surface of a thick-walled cylindrical material is cut to form a tapered inner circumferential surface. As a result, the manufacturing cost of cylindrical parts increases due to wear of the cutting tool and deterioration of material yield.

Furthermore, even if a cylindrical material is formed with high precision, when cutting it, the machining accuracy decreases due to defects in the cutting tool (for example, misalignment of the rotation axis, wear of the cutting blade, etc.), and the finished product is There was also the problem that the quality of the tapered inner cylindrical part became unstable.

The present invention has been made in view of the above problems, and aims to suppress manufacturing costs of cylindrical parts and stabilize quality.

(Means for Solving the Problems) A feature of the forging method for cylindrical parts according to the present invention to achieve the above object is that a cylindrical material having a uniform inner diameter and an outer diameter is By inserting the cylindrical material into a die having a hollow portion, and then upsetting both end surfaces of the cylindrical material with a punch, the longitudinal center portion of the cylindrical material is made the thickest portion, and the inner part of the cylindrical material in the direction of both ends is expanded from this center portion. The reason is that the circumferential surfaces are respectively tapered surfaces.

(Function) As described above, a cylindrical part having a tapered inner peripheral surface that expands in both directions is forged.
A tapered inner cylindrical part can be easily formed by simply performing compression using a forging die with a simple configuration, taking advantage of the deformable nature of the cylindrical material. Moreover, since the plastic processing called forging is used, the finished cylindrical part can be given strength characteristics such as toughness, and the precision of the cylindrical part is also improved.

Furthermore, by providing a tapered guide part on the pressing end surface of the forging die punch with a tapered outer circumferential surface corresponding to the tapered inner circumferential surface of the cylindrical part, the machining accuracy of the shape of the cylindrical part can be achieved with high reliability. It is also possible to make it a thing.

As described above, the yield of materials is improved,
Since there is no wear of cutting tools, etc., manufacturing costs can be reduced, and a tapered inner circumferential cylindrical part with stable quality can be obtained by improving machining accuracy.

(Example) Hereinafter, an example of the forging method for a cylindrical component according to the present invention will be described in detail using the drawings.

1 to 3 are for explaining one embodiment of the present invention, and FIG. 1 is a partially cutaway perspective view showing a casting mold used in the method of the present invention, and FIGS.
The figures are partially cutaway perspective views showing the forging process.

In each figure, the forging die 1 includes a cylindrical die 3 whose outer circumferential side is reinforced by a reinforcing ring 2, a punch 4 that fits into the hollow part 3a of the die 3 from above and below,
5. Taper guide portions 4b and 5b each having a tapered outer circumferential surface whose diameter decreases toward the tip in the pressing direction are formed protruding from the lower end surface 4a and upper end surface 5a, which are the pressing surfaces of the punches 4 and 5, respectively.

The process of forging a cylindrical material 6 into a tapered inner cylindrical part 7 using the forging die 1 having the above configuration will be described with reference to FIGS. 1 to 3. First, as shown in FIG. 1, the cylindrical material 6 is placed in the hollow part 3a of the die 3. At this time, the inner peripheral surface of the hollow portion 3a of the die 3 and the outer peripheral surface 6a of the cylindrical material 6 are set to have substantially the same diameter.

Next, as shown in FIG. 2, the punches 4 and 5 are synchronized and lowered and raised from above and below the hollow portion 3a, so that both end surfaces 6b and 6b of the cylindrical material 6 and the punch 4,
The end surfaces 4a and 5a of 5 are brought into contact with each other. In this state, when the punches 4 and 5 are further advanced in the pressing direction, the cylindrical material 6 is pressed from both ends, and since the outer peripheral side 6a is in close contact with the inner peripheral surface of the hollow part 3a of the die 3, the cylindrical material 6 is pressed from both ends. The inner circumferential surface 6c side of 6 is pushed out along the tapered surface of the guide portions 4b and 5b,
As shown in FIG. 3, the cylindrical component 7 has an inner circumferential surface 7a that bulges out, a central portion in the longitudinal direction being the thickest portion, and inner circumferential surfaces 7a tapered on both end faces.
is completed.

As an effect specific to the embodiment described above, taper guide portions 4a, 5b having tapered outer peripheral surfaces are formed protrudingly on the upper and lower end surfaces 4a, 5a of the punches 4, 5, respectively, and the cylindrical material 6 is By pressing, the inner circumferential surface of the die hollow part 3a, the punch end surfaces 4a, 5
Since the cylindrical part 7 is obtained by surrounding and forging each surface of the outer peripheral surfaces of the tapered guide parts 4b and 5b, the cylindrical part 7 has high shape accuracy.

Also, the punches 4 and 5 are connected to the taper guide portions 4a and 5b.
The forging process is completed by simply pressing the forging die 1 until the tip surfaces of the forging die 1 come into contact with the cylindrical part 7. Therefore, there is no need to control the working operation of the forging die 1 using a complicated control mechanism in order to keep the length of the cylindrical part 7 constant. Another unique effect is that the forging process can be controlled with a simple configuration of setting the shape of the pressing surface of the punch.

It should be noted that what has been described above merely shows one embodiment of the present invention, and any modifications and changes may be made without departing from the purpose, structure, and effects of the present invention.

For example, taper guide portions 4 are provided on the end surfaces of punches 4 and 5.
b, 5b, the present invention is not limited thereto, but as shown in FIGS. Arranging the cylindrical material 16 having
Punch 1 the end surfaces 16b, 16b of the cylindrical material 16.
4 and 15 may be pressed by the end surfaces 14a and 15a, and a cylindrical component 17 having an enlarged diameter and a tapered surface may be formed at both ends of the inner circumferential surface 17a by forging.

By forging as described above using the punches 14 and 15 configured as described above, it is possible to form a cylindrical component in which the central portion in the longitudinal direction of the inner circumferential surface is thicker than the end portions without being constrained by accuracy. is possible,
It has the unique effect of simplifying forging equipment and improving processing efficiency by making the manufacturing process easier.

(Effects of the Invention) As described above in detail, the forging method for cylindrical parts according to the present invention provides the following effects.

First, a cylindrical material is placed in a die having a hollow part with approximately the same diameter as the outer peripheral surface of the cylindrical material, and both end surfaces of the cylindrical material are upset with a punch to make the longitudinal center part the thickest part. By forging a cylindrical part with tapered inner circumferential surfaces at both ends, there is no tool wear or material yield deterioration that occurs in cutting processes, and manufacturing costs are reduced. can be suppressed.

Further, since the cylindrical material is forged from both end faces and deformation in the outer circumferential direction is prevented, the processing accuracy of the cylindrical part having a tapered circumferential surface can be improved, and the quality can be stabilized.

Furthermore, regardless of the manufacturing method of the material, the completed cylindrical part is forged using a forging die, so the density of the material becomes tight and uniform, which also has the secondary effect of improving tenacity.

[Brief explanation of drawings]

1 to 3 show an embodiment of the forging method for cylindrical parts according to the present invention, and FIG. 1 is a partially cutaway perspective view showing a forging die used in this embodiment, and FIG. 3 are partially cutaway perspective views showing the forging process. Furthermore, FIGS. 4 and 5 are perspective views illustrating another embodiment of the forging method for cylindrical parts according to the present invention. 3, 13...Die, 3a, 13a...Hollow part,
4, 5, 14, 15...Ponchi, 4a, 5a, 1
4a, 15a... Pressing end surface, 4b, 5b... Taper guide portion, 6, 16... Cylindrical material, 7, 17...
Cylindrical parts, 7a, 17a...Tapered inner peripheral surface.

Claims (1)

[Scope of Claims] 1. Inserting a cylindrical material having uniform inner and outer diameters into a die having a hollow portion with approximately the same diameter as the outer diameter, and then upsetting both end surfaces of the cylindrical material with a punch. A forging method for a cylindrical part, characterized in that the central part in the longitudinal direction of the cylindrical material is the thickest part, and the inner circumferential surfaces in the direction from the central part to both ends are tapered surfaces. 2 A tapered guide portion having an outer circumferential surface corresponding to a desired tapered inner circumferential surface of the cylindrical component is protrudingly provided on the end face of the punch, so that when the cylindrical material is upset by the punch, the inner circumferential surface of the cylindrical material is 2. The method for forging a cylindrical component according to claim 1, wherein the tapered guide portion has a tapered surface along the outer circumferential surface thereof.