JPH08141688A - Forging method of gear - Google Patents

Abstract

PURPOSE: To form a gear with a forging, in the forging method for gear with a rotary swaging machine arranging a die for forming the gear. CONSTITUTION: The die 16 for forming the gear is arranged in the rotary swaging machine and the gear having many teeth is formed by forming the same number of teeth as the dies 16 without rotating a blank 15 or with a small number of dies 16 by applying the rotation of the blank 15. However, in the latter case, at the time of shifting to the following stroke part of the die 16, the already formed tooth form is ridden across by executing one stroke quantity of the die 16 with the same as or higher than the tooth height of the targeted gear so as to prevent the collision of the tooth form and the die 16, and the blank 15 can be made to be smoothly rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear forging method using a rotary waving machine having a gear forming die.

[0002]

2. Description of the Related Art In the conventional gear forging method, as shown in FIG. 1, a material 1 is formed on a die 1 having a tooth forming blade 2 on its inner circumference.
Extrusion method, die 4 as shown in Figure 2
Method of forming a tooth profile by pushing the material 7 into the inner blade 5 of the machine with upper and lower punches 6, a method of rolling with a rack type or a round die, or JP-A-59-1991.
As shown in FIG. 3 disclosed in Japanese Patent Publication No. 41, no.
There is a method of forming a tooth profile by hot forging in which the material 9 is sequentially rotated at a pitch angle by a pressing force of each tooth profile punch 8 and heated by a high frequency heating source 12 or the like.

[0003]

The above-described conventional gear forging method has the following problems. In the method in which the material 3 is extruded and passed through the die 1 having the tooth forming blade 2 on its inner circumference or is pushed into the blade of the die 4, the materials 3 and 7 are plastically deformed by the blades formed in the dies 1 and 4. In order to accurately form a desired gear, it is necessary to manufacture large-scale dies 1 and 4 having high rigidity.

The method of forming the material 9 while sequentially rotating the material 9 at the pitch angle by the tooth profile punch 8 is one tooth profile or two tooth profiles.
It takes a lot of time to form each piece individually. Further, since the tooth profile is formed by one stroke of the tooth profile punch 8, it is difficult to form due to work hardening in the cold, so the material 9 is hot-worked while being heated by a high frequency or the like. At this time, there are problems such as dimensional change due to heating and cooling and scale generation due to oxidation. An object of the present invention is to forge gears such as spur gears and helical gears by using a rotary waving machine capable of hitting a large number of dies at the same time.

[0005]

In order to achieve the above object, in the gear forging method of the present invention, several dies for gear forming are evenly arranged in a rotary wazing machine, and the dies between the dies and the hammer are arranged. While moving the die toward the center of the material one after another by the wedge in Fig. 2, the tooth profile is forged by repeatedly striking the material from the direction in which the die is arranged. The die is repeatedly hit,
When the material is rotated, the amount of impact must be equal to or greater than the target gear tooth height. One of the dice
In order to make the amount of impact equal to or greater than the tooth height, it is preferable that the amount of the hammer mounted on the roller be equal to or greater than the tooth height of the target gear.

[0006]

The amount of one impact of the tooth forming die placed on the rotary waving machine as described above is determined by the amount of the hammer riding on the roller. When a gear with a large number of teeth is to be formed with a small number of dies (about 2 to 4), the material must be rotated. Therefore, when one impact amount of the die is made smaller than the target tooth height of the gear, the die is prevented from impacting between the next tooth profiles. That is, when the impact amount of the die is larger than the tooth height of the target gear, when the die impacts between the next tooth profiles, the die crosses over the already formed tooth profile and prevents the tooth profile from colliding with the die. Can be rotated smoothly.

[0007]

The present invention will be described below with reference to the accompanying drawings. FIG. 4 shows an outline of the rotary waving machine. The rotary waving machine has a housing 13
Alternatively, the spindle 19 is rotated, and when the hammer 18 rides on the roller 14, the raw material 15 is struck by the die 16 once in the radial direction, and the wedge 17 between the die 16 and the hammer 18 is further ejected to successively produce the die 16. It is a machine for cold working the material 15 from a large diameter to a small diameter while moving in the center direction.

FIG. 5 shows a tooth forming method. In the case of the housing drive system, if the rotation of the spindle 19 is stopped, the die 16 does not rotate. Therefore, by disposing the tooth forming die 16 facing the tooth profile of the target gear by the same number of teeth as the tooth profile. Can be molded. That is, FIG.
In this case, the gear has eight teeth, and eight dies 16 for forming teeth facing each other between the tooth profiles may be evenly arranged on the swaging machine. Material 1 in this case
Since 5 is not rotated, one impact amount of the die 16 may be smaller than the target tooth height of the gear.

On the other hand, when the number of teeth is several tens, it becomes difficult to arrange the same number of dies 16 as the number of teeth.
A molding method using several (about 2 to 4) dies 16 will be described below. Similarly to the above, when the spindle is fixed by the housing drive method, the number of hits S of one die 16 (striking / m
in) is represented by S = R · Nk. R is the number of rollers 11, and Nk is the number of rotations (rpm) of the roller cage 20.

Here, if the rotation of the material 15 is fixed, the number of teeth is 2, 3 in the 2, 3 or 4 die system, respectively.
Alternatively, since only 4 gears can be formed, the number of teeth is increased by rotating the material 15. Dice 1
The number of teeth M that can be formed for the number n of 6 is determined by M = n · m, and when forming a gear with the number of teeth M, the rotation speed Nw of the material 15 is shown by Nw = S · m / M. Be done. m is an integer. For example, when molding a gear having a number of teeth M = 52, a module = 1, and a tooth height = 2.3 mm, the number of rollers 11 is R =
When twelve housing-driven swaging machines are used, the outer diameter Ds of the spindle 19 is 340 mm,
Inner diameter Dh of housing 13 = 460 mm, housing 1
3 rotation speed Nh = 80 rpm, Nk = Nh · D
From h / (Ds + Dh), the rotation speed Nk of the roller cage 20
Is 46 rpm, and the number of hits S of the die 16 is 552 hits / min. The number of teeth M (52) = 4 dice × 1
Dispose 4 dies 16 by 3 and set the material 15 to Nw =
It is molded by rotating at an integral multiple of 10.6 rpm. In this case, since the material 15 is rotating, one hit amount of the die 16 is adjusted so as to be larger than the target gear tooth height of 2.3 mm.

FIG. 6 shows a method of adjusting the amount of one hit of the die 16. FIG. 6 shows details before and after the hammer 18 rides on the roller 14. The hammer 18 has a hammer roller 21 at its tip, and the hammer roller 21 slides on the roller cage 20. When the hammer roller 21 comes into contact with the roller 14 and rides on the roller 14, the hammer 18 becomes the material 15.
Since it is pushed in the direction of, the one hit amount of the die 16 is determined by the gap h between the roller cage 20 and the roller 14. By setting the gap h to have a tooth length of 2.3 mm or more, the die 16 can overcome the tooth profile even if the material 15 rotates.

The tooth forming die 16 used at this time may basically have a shape in which the tooth profile of the target gear is opposed to each other. However, since the material 15 rotates by a certain angle Δθ during the time ΔT of one hit of the die 16, it is necessary to make the die 16 slightly narrower than the target tooth profile of the gear.

FIG. 7 shows a method of calculating the time ΔT for one impact of the die and the angle Δθ at which the material 15 rotates during that time. The time ΔT for hitting the die 1 is the time when the hammer 18, that is, the hammer roller 21 rides on the roller 14. Therefore, considering that the roller 14 moves by the distance x on the circle of Dk = Ds + 2h, which is obtained by adding the one hit amount h of the die 16 to the outer diameter Ds of the spindle 19 during one hit of the die, the rotation speed of the roller cage 20 is changed. ΔT = 2√ (((Dr / 2) ² − ((Dr / 2) −h) ² ) because ΔT is moving at Nk.
It is shown by / (Nk * Dk * (pi)). The numerator of this formula indicates the distance x.

Further, the angle Δθ at which the material 15 rotates during ΔT is represented by Δθ = 360Nw · ΔT. When ΔT and Δθ when the number of teeth M = 52 is calculated from the above equation, the die 1 is obtained when the outer diameter Dr of the roller 14 is 60 mm.
6 with 1 hitting time ΔT = 0.02 sec, Δθ = 1.7
It becomes 7 °. Therefore, FIG. 8 shows a schematic cross-sectional view of the tooth forming die 16, and the material from the material 22 shown by the dotted line to the material 23 shown by the solid line is Δθ = 1.7 while the die 16 makes one impact.
Since it rotates by 7 °, it is necessary to prepare the tooth forming die 16 that corrects this amount.

[0015]

As described above, according to the present invention, a gear is formed by arranging a large number of teeth forming dies on a rotary waving machine. Generally, when a material is forged, work hardening occurs and processing becomes difficult,
The swaging processed surface layer undergoes dynamic recovery due to repeated plastic deformation even at room temperature, and it is possible to form a relatively hard material without heating because it can form a good tooth formation shape without hardening.
Highly accurate tooth profile can be formed without dimensional change due to heating and cooling and scale generation due to oxidation. The number of hits of the die depends on the number of rollers and the number of revolutions of the housing or spindle, but it is possible to hit several hundreds to several thousands of revolutions per minute, and the processing time is several seconds to several tens of seconds.

[Brief description of drawings]

FIG. 1 is a perspective view showing a method of extrusion molding a gear with a die having a blade on its inner circumference.

FIG. 2 is a side view showing a method of push-molding a gear using a die having a blade on its inner circumference.

FIG. 3 is a perspective view showing a method for forming a gear by pressing force of a tooth-shaped punch.

FIG. 4 is a side view and a front view showing a schematic configuration of a rotary waving machine.

FIG. 5 is a front view for explaining a molding method using the same number of dies as the number of teeth.

FIG. 6 is an enlarged front view showing a method for adjusting the amount of one hit of the die.

FIG. 7 is a schematic diagram illustrating a method of calculating a single hitting time of a die and a rotation angle of a material.

FIG. 8 is a front view showing a tooth forming die for which the amount of rotation of the material is corrected.

[Explanation of symbols]

1, 4, 16 are dies, 2, 5 are inner blades, 3, 7, 9, 1
5, 22, and 23 are materials, 4 are dies, 6 are upper and lower punches, 8 is a tooth punch, 10 is a mandrel, 11 is a stopper, 12 is a high-frequency heating source, 13 is a housing, 14 is a roller, 17 is a wedge, 18 Is a hammer, 19 is a spindle, 20 is a roller cage, and 21 is a hammer roller.

Claims (2)

[Claims] 1. A gear forging method, comprising: arranging a gear for forming a gear on a rotary waving machine, and forming a tooth profile by hitting the material with the die. 2. The gear forging method according to claim 1, wherein the amount of one impact of the die when rotating the material is equal to or greater than the tooth height of the target gear.