JPH035037A - Gold forging shaft having special shaped part at one end and its manufacture and apparatus thereof - Google Patents

Abstract

PURPOSE:To obtain the excellent cold forging shaft without decreasing of its strength by forming a flange part at the intermediate part on the cold forging shaft having special shaped part at one end and forming the tapered part becoming gradually smaller diameter at the opposite base part against the above special shaped part. CONSTITUTION:The special shaped part 12 is formed with extrusion working at the one end part of rod material. While the special shaped part is being restricted, the opposite part is drawn with extrusion working. The flange part 13 is formed with the upsetting at the intermediate part and also the tapered part 14 becoming gradually smaller diameter and continuing to the base of this flange part is formed. Therefore the shape changing at the continuing part is become gentle and so the stress against the torsion is dispersed easily at the correcting time and the driving power transmission, and its strength is increased. The cold forging work for the shaft having the special shaped part is executed efficiently and easily with a series of processes and, especially, the special shaped part is obtained with high accuracy by forming again.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a cold-forged shaft having an irregularly shaped part such as a gear or a serenoid at one end, such as used in an armature shaft of a starter motor of an internal combustion engine. The present invention relates to a manufacturing method and an apparatus for manufacturing the same.

[Prior Art] Generally, as shown in FIG. 8, for example, one end of an armature shaft 2 used in a starter motor 1 of an internal combustion engine has a gear 3 connected to the crankshaft of the internal combustion engine via a one-way clutch. is formed.

By the way, the formation of the external shape of the armature shaft 2 and the formation of the gear 3 are generally performed by cutting, or cold forging has been attempted to simplify the manufacturing process.

The conventional cold forging of the rotor shaft 2 is carried out by the method shown in FIGS. 9 to 11.

That is, a bar W1 as a raw material as shown in FIG. 9 is prepared, and this bar W1 is squeezed by forward extrusion using a forging die to form a small diameter portion 4a and a large diameter portion 4b as shown in FIG. Next, as shown in FIG. 11, a small diameter portion 4a is formed using another mold.
is narrowed again to form a small diameter part 4a having uniform external dimensions, and the end of the large diameter part 4b is slightly narrowed to form a flange part 4c, and the other end of the large diameter part 4b is formed into a flange part 4C. The armature shaft 2 is obtained by forming a gear 3 to a predetermined length.

[Problems to be Solved by the Invention] However, the above-described conventional armature shaft 2 causes the following problems.

That is, when the armature shaft 2 is formed by cold forging as described above, the armature shaft 2 may be bent due to the heat treatment after forming, and the bend must be corrected after forming. At this time, since the continuous portion between the small diameter portion 4a and the flange portion 4C changes greatly in shape, stress due to the straightening force concentrates on this continuous portion, resulting in problems such as damage.

Furthermore, when the starter motor 1 is started, the armature shaft 2 is twisted due to the reaction force from the crankshaft, but the torsional force and torsional vibration at this time are also caused by the small diameter portion 4a and the flange portion 4C as described above. This may cause stress concentration in the continuous portion with the armature shaft 2, leading to a decrease in the strength of the armature shaft 2.

[Means for Solving the Problems] The present invention aims to provide a cold-forged shaft having an irregularly shaped portion at one end, a method for manufacturing the same, and a manufacturing device thereof, which can effectively solve the above-mentioned problems. In the first embodiment, a cold forged shaft having an irregularly shaped part at one end, a flange part is formed in the middle part in the length direction, and a base part of the flange part on the opposite side from the irregularly shaped part has a gradually smaller diameter. It is characterized by having a tapered portion formed therein.

Further, the second aspect of the method for manufacturing a cold forged shaft having an irregularly shaped portion at one end is characterized by having the following steps 11 (1) and (3).

■ A process in which an irregularly shaped part is formed at one end of an unprocessed bar by extrusion.

(2) After step I, a step of squeezing the side opposite to the irregularly shaped part by extrusion while the irregularly shaped part is restrained.

III. After the above step II, a step of forming a flange portion in the intermediate portion by upsetting, and forming a tapered portion that gradually becomes smaller in diameter following the base of the flange portion.

Furthermore, the third aspect of the manufacturing apparatus for a cold forged shaft having an irregularly shaped portion at one end includes a pair of first and second dies, and a transfer of the shaft between these dies. the first mold includes a sizing hole in one of the molds that is opened toward the other mold and that restricts the outer shape of the cold forged shaft; teeth for forming a deformed shape portion formed at an inner end of the second mold, one end of the cold forged shaft is inserted into one of the second molds, and the cold forged shaft is inserted into the second mold. Teeth are formed to adjust the shape of the irregularly shaped part formed on the shaft, and the other mold is opened toward the one mold, and the diameter gradually decreases from the open end toward the inside. A sizing hole with a tapered portion is formed.

[Operation] According to the cold forged shaft having an irregularly shaped portion at one end according to the first aspect of the present invention, this is achieved by connecting the continuous portion between the flange portion and the other portion following the flange portion through the tapered portion. The shape change of the continuous portion is made gentler, thereby smoothing stress distribution during twisting during straightening or power transmission, thereby improving strength.

Further, according to the manufacturing method according to the second aspect, cold forging of a shaft having an irregularly shaped portion at one end can be efficiently and easily performed through a series of steps, and in particular, the irregularly shaped portion can be Since it is formed by one mold and then re-molded by upsetting with a second mold to adjust its shape, it has extremely high precision.

Further, according to the manufacturing apparatus according to the third aspect, the manufacturing method described above can be carried out smoothly.

[Example] Hereinafter, an example of the first aspect of the present invention will be described based on FIGS. 1 and 2.

Reference numeral 10 in FIG. 1 indicates a cold forged shaft according to this embodiment, in which a gear 12 which is an irregularly shaped part is formed at one end of the shaft main body 11, and a flange part 13 is formed in the middle part of the shaft main body 11. As shown in FIG. 2, a tapered part 14 whose diameter gradually becomes smaller is formed at the base of the flange part 13 on the opposite side from the gear 12, and a small diameter part 15 is formed at the other end. The length from the flange portion 13 to the end on the small diameter portion 15 side is longer than the length from the flange portion 13 to the end on the gear 12 side. The tapered portion 14 is formed on the small diameter portion 15 side.

This shaft 10 is used for the starter motor described above.
It is mounted by inserting the small diameter portion 15 into the bearing of the housing.

Therefore, the cold forged shaft 10 of this embodiment configured as described above bends during heat treatment, and when it becomes necessary to correct the bend, even if an external force perpendicular to the axial direction is applied, the taper does not bend. Since the portion 14 provides a gentle cross-sectional change from the shaft body portion 11 on the small diameter portion 15 side to the flange portion 13, the flange portion 1
3 and the shaft body 11 are smoothly dispersed, and stress concentration is avoided.

Therefore, a decrease in strength during straightening is suppressed, and quality can be easily ensured.

Further, for the above-mentioned reason, stress concentration can be avoided and the strength can be improved even when the cold forged shaft 10 is attached to a starter motor or the like and used for power transmission.

Next, FIG. 3 to FIG. 7 and FIG.
This will be explained based on the diagram.

Reference numeral 20 in FIG. 3 indicates a manufacturing apparatus for a cold forged shaft according to this embodiment, in which a pair of first and second molds 21 and 22 and a cold-forging shaft are formed between these molds 21 and 22. The forged shaft 10 is also provided with a conveying device 23 that transfers the forged shaft 10.

The first mold 21 has a sizing hole 24 that is opened toward the other mold 21b in one mold 21a and that restricts the outer shape of the cold forged shaft IO, and an inner part of the sizing hole 24. Teeth 25 for forming a gear (11) are formed at the end.

One end of the cold forged shaft 10 is inserted into the second mold 22, and one end of the cold forged shaft 10 is inserted into the second mold 22.
Teeth 26 are formed to adjust the shape of the gear 11 formed in the mold 22H, and the other mold 22H is opened toward the one mold 22b, and as shown in FIG. A sizing hole 27 is formed with a tapered portion 27a that gradually becomes smaller in diameter toward the inside.

To explain these in detail, the sizing hole 24 formed in one of the molds 21a constituting the first mold 21 extends inward (downward in FIG. 3) as shown in FIG. It is formed so that the diameter becomes gradually smaller as it goes, and a knockout pin 28 for pushing out the cold forged shaft 10 formed by the sizing hole 24 from the sizing hole 24 is slidably inserted inside. .

Also, similar knockout pins 29 and 30 are slidably inserted into both molds 22a and 22b of the second mold 22.

Further, the sizing hole 27 formed in the second mold 22 has a larger diameter overall than the sizing hole 24 formed in the first mold 21, and has a smaller diameter on the lower end side. It has a two-tiered shape.

As shown in FIG. 5, the conveyance device 23 is equipped with clamps 31 and 32 corresponding to each of the molds 21 and 22, and is moved back and forth as a whole along the arrangement direction of the molds 21 and 22. and each clamp 3
1 and 32 are molds 21 for each set. a, 21b, 22a
and 22b are spaced apart from each other, and the cold forged shaft 1
The cold forged shaft 10 is gripped when it is pushed out of the molds 21 and 22.

Further, a clamp 31 provided corresponding to the first mold 21 is provided with a clamp 31 in response to the reciprocating motion of the conveying device 23.
A reversing mechanism 33 that rotates 1 by 180 degrees is connected thereto.

As shown in FIG. 6, the reversing mechanism 33 has a pinion 34 integrally attached to the clamp 31, and is always kept in mesh with the pinion 34.
1, and an actuator 36 fixed to the clamp 31. When the clamp 31 moves, the actuator 36 rotates the drive gear 35 and the pinion gear 34, The clamp 31 is adapted to be reversed.

On the other hand, the molds 21 and 22 are arranged at the same pitch, and the moving range of the conveying device 23 is also made to match the pitch, and furthermore, by moving the conveying device 23 by one pitch, The clamp 31 is rotated by 180 degrees by a reversing mechanism 33 so that the first mold 21 faces the second mold 22.

Next, the manufacturing apparatus 20 of this embodiment configured as described above
The manufacturing method according to the second aspect of the present invention will be explained together with the operation thereof.

First, the unprocessed cylindrical bar shown in FIG. 7(a) is inserted into the sizing hole 24 of the first mold 21 up to the tooth 26, and then The molds 21b and 22b located above in FIG. 3 are moved toward the molds 21a and 22a located below in FIG.
The first mold 21 performs forward extrusion processing on the bar.

By processing with this first mold 21, as shown in FIG. 7(b), a cold forged semi-processed state is formed in which a gear 12 is formed at one end and the diameter is expanded in multiple steps toward the other end. Shaft I
O is formed.

When the processing is completed and the upper molds 21b and 22b and the lower molds 21a and 22a are separated, the cold forged shaft 10 formed in the first mold 21 is moved to the first mold by the knockout pin 28. is pulled out from the mold 21 and held by the clamp 31 of the transport mechanism 23.

At this time, since the cold forged shaft 10 is formed in a multi-step shape by the steps formed on the inner diameter of the sizing hole 24 of the first mold 21, the mold 21 is moved by a small relative movement.
The adhesion force, that is, the frictional resistance, is reduced, making removal easier.

By the subsequent movement of the conveyance mechanism 23, the cold forging shaft 10 is separated from the first mold 21, and is also reversed by 180° to a predetermined position in the mold 22a below the second mold 22. Then, by releasing the grip by the clamp 31, the cold forged shaft 10 is inserted in the inverted state 4 up to the small diameter portion of the sizing hole 27 of the lower mold 22a.

Simultaneously with the insertion of the cold forged shaft 10 into the sizing hole 27, a new bar material is supplied to the first mold 21.

When inserting the cold forged shaft 10 into the sizing hole 27 of the second die 22, since the taper forming part 27a is provided at the open end of the sizing hole 27,
The cold forged shaft 10 is guided by the inclination of the taper forming portion 27II, and is inserted smoothly and reliably.

Next, the upper molds 21b and 22b are replaced again with the lower mold 2.
By lowering it toward 1a and 22a, cold forging is performed in the first die 21 and the second die 22.

Here, in the second mold 22, the two molds 22
b, when the first mold 2 is lowered by the teeth 26.
In step 1, the gear 12 formed on the cold-forged shirt 10 is squeezed to adjust its shape, and the end opposite to the gear 12 is squeezed to form the small diameter portion 15. When the tip of the small diameter portion 15 hits the knockout pin 29 and the downward movement stops, the upsetting process is started, and the flange portion 13 is formed at the intermediate portion (from the gear 12) of the shaft body portion 11 of the cold forged shaft 10. A tapered portion 14 is simultaneously formed near the flange portion 13 on the opposite side by the taper forming portion 27a.

As a result, the cold forged shaft IO having the final shape shown in FIG. 1 is obtained.

The size of the flange portion 13 changes depending on the position where the tip of the small diameter portion 15 of the shaft 10 abuts the knockout pin 29.
It is also possible not to form the flange portion 13.

The cold forged shaft 10 thus formed is gripped by the clamp 32 and discharged.

With the manufacturing method and manufacturing apparatus 20 of the cold-forged shirt 10 of this embodiment, the cold-forging shaft IO having the gear 12 at one end can be efficiently and easily cold-forged through a series of steps. It can be carried out. Especially that gear
Since it is formed by the first mold 21 and then re-molded by upsetting with the second mold 22, its shape is adjusted, so that it has extremely high precision.

Note that the above example is just an example, and various changes can be made based on design requirements and the like. For example, the gear is not limited to being formed at the tip of the shaft, but may be serrations, knurling, prismatic, etc. In short, any irregular shape smaller than the outer diameter of the shaft may be used.

[Effects of the Invention] As explained above, according to the cold forged shaft having the irregularly shaped portion at one end according to the first aspect of the present invention, the flange portion is formed at the intermediate portion in the length direction, and the flange portion is formed at the intermediate portion in the longitudinal direction. The flange part is characterized by a taper part that gradually becomes smaller in diameter at the base on the opposite side of the gear, and by connecting the continuous part of the flange part and other parts following it by a tapered part. This has the effect of slowing down the shape change of this continuous portion, thereby smoothing stress distribution during twisting during straightening or power transmission, and thereby improving strength.

Further, according to the method for manufacturing a cold-forged shaft having an irregularly shaped portion at one end according to the second aspect of the present invention, I. forming an irregularly shaped portion at one end of an unprocessed bar material by extrusion processing; and (1) After the step I, a step of squeezing the side opposite to the irregularly shaped part by extrusion while the irregularly shaped part is restrained; Cold forging of a shaft with an irregularly shaped part at one end is characterized by forming a flange part and forming a tapered part with a gradually smaller diameter following the base of the flange part. This can be done efficiently and easily through a series of steps, and in particular, the irregularly shaped part is formed by the first mold and then re-molded by upsetting with the second mold. Since the shape can be adjusted, products with extremely high precision can be obtained.

Furthermore, according to the apparatus for manufacturing a shaft having an irregularly shaped portion at one end according to the third aspect of the present invention, the first
and a second mold, and a conveying device that transfers a shaft between these molds, the first mold being opened into one mold toward the other mold. Additionally, a sizing hole for constraining the outer shape of the cold-forged shaft and teeth for forming an irregularly shaped part formed at the inner end of the sizing hole are provided, and the second mold is configured to fit one of the two molds. The die is formed with teeth into which one end of the cold-forged shaft is inserted to adjust the shape of the irregularly shaped portion formed on the cold-forged shaft, and the other die is provided with teeth that adjust the shape of the irregularly shaped portion formed on the cold-forged shaft. The manufacturing method described above can be carried out smoothly because the sizing hole is formed with a tapered portion that is opened toward the inside and gradually becomes smaller in diameter from the open end toward the inside.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the first aspect of the present invention, in which FIG. 1 is a front view, FIG. 2 is an enlarged vertical sectional view of the flange portion and its surroundings, and FIGS. FIG. 6 shows an embodiment of the third aspect of the present invention, in which FIG. 3 is a longitudinal sectional view, FIG. 4 is an enlarged longitudinal sectional view of a part of the second mold,
Fig. 5 is a schematic plan view of the conveyance device, and Fig. 6 is the VI of Fig. 5.
-A cross-sectional view taken along the line -1111, Figure 7(a) is a front view showing the unprocessed bar, and Figure 7(b) shows the cold forged shaft after it has been forged by the first die. The front views shown in FIGS. 8 to 11 are for explaining a conventional cold-forged shaft, and FIG. 8 is a partially sectional front view showing a starter motor to which the cold-forged shaft is applied, and FIG. 11 through 11 are front views of a cold-forged shaft showing stepwise forging of the cold-forged shaft. O...Cold forged shaft, 1...Shaft main body, 2...Gear (oddly shaped part), 3...Flange part, 4...Tapered part, 5... Small diameter part, 0...Cold forged shaft manufacturing device, 1...First mold, 2...Second mold, 3...Transfer device, 4.27... Sizing hole, 5.26... Teeth, 7a... Taper forming part, 1.32... Clamp, 3... Reversing mechanism.

Claims (3)

[Claims] (1) A cold-forged shaft with an irregularly shaped part at one end, a flange part is formed in the middle part in the length direction, and the diameter of the flange part gradually decreases at the base on the opposite side of the irregularly shaped part. A cold-forged shaft having an irregularly shaped portion at one end, characterized in that a tapered portion is formed. (2) A method for manufacturing a cold-forged shaft with an irregularly shaped portion at one end, the method comprising the following steps I, II, and III. Method. I. A process of forming an irregularly shaped part on one end of an unprocessed bar by extrusion processing. II. After step I above, a step of squeezing the side opposite to the irregularly shaped part by extrusion while the irregularly shaped part is restrained. III. After the above step II, a step of forming a flange portion in the intermediate portion by upsetting, and forming a tapered portion that gradually becomes smaller in diameter following the base of the flange portion. (3) A manufacturing device for a cold-forged shaft having an irregularly shaped portion at one end, comprising first and second molds arranged in a pair;
a conveying device that transfers the shaft between these molds, and the first mold has an opening in one of the molds toward the other mold, and has an outer shape of the cold-forged shaft. The second mold is provided with a sizing hole for restraining the cold-forged shaft, and teeth for forming an irregularly shaped part formed at the inner end of the sizing hole. Teeth are formed into which one end is inserted to adjust the shape of the irregularly shaped part formed on this cold forged shaft, and the other mold is opened toward the one mold, and the open end thereof is formed. 1. A manufacturing device for a cold forged shaft having an irregularly shaped portion at one end, the sizing hole having a tapered portion whose diameter gradually decreases from the portion to the inside.