JPH0767592B2 - Bevel gear forging method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bevel gear forging method for manufacturing a bevel gear by cold forging.

[Conventional technology]

Generally, bevel gears are widely used for power transmissions of various machines or differentials of self-propelled vehicles such as automobiles and tractors.

Conventionally, such a bevel gear is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-177845.
It is manufactured by the method as disclosed in the publication.

FIG. 7 shows a bevel gear forging apparatus disclosed in this publication. In the drawing, reference numeral 11 is a material 13 for forming a bevel gear.
1 shows a die with holes 15 for inserting

In front of the hole portion 15 of the die 11, a tooth profile portion 17 having a shape corresponding to the tooth profile of the bevel gear to be molded is carved.

An open portion 19 having a shape as shown in FIG. 8 is formed in front of the tooth profile 17 so as to communicate with the tooth profile 17.

In the drawing, reference numeral 21 indicates a punch, reference numeral 23 indicates a knockout pin, and reference numeral 25 indicates a shaft hole of the material 13.
27 shows a pin inserted into 27.

In the bevel gear forging device as described above, the material 13 is inserted into the hole 15
After being accommodated in the inside, the tooth 13 is sequentially filled with the material 13 by the forward extrusion process by the punch 21, and further, as shown in FIG. 9, an opening 19 formed in front of the tooth 17 of the die 11 is formed. The bevel gear is pressed by extruding a part of the material 11 as extra thickness.

Further, according to such a bevel gear forging method, the tooth profile portion is formed.
Since the open part 19 is provided in front of the 17, the extra material material escapes to the open part 19, and it is possible to perform the forging by the steady plastic flow under a constant pressure regardless of the volume of the material material. It is possible to effectively prevent a decrease in accuracy due to a variation in volume, and to effectively prevent a decrease in product accuracy due to the excessive lubricating oil, lubricant, scale, etc. being discharged from the open portion 19. It has the effect of being able to

[Problems to be Solved by the Invention]

However, in such a conventional bevel gear forging method, as shown in FIG.
Since the shape of 19 is a tooth shape that is continuous with the toothed portion 17, when removing the excess thickness extruded in the open portion 19 by cutting or the like, intermittent cutting occurs, and burr occurs,
Since this burr interferes with the mating gear, there is a problem that the burr needs to be reliably removed.

On the other hand, in order to solve such a problem, it may be considered that the diameter of the open portion 19 is simply made smaller than the diameter of the conical tip portion of the bevel gear. There has been a problem that the load increases and the life of the mold becomes extremely short.

The present invention has solved the above-mentioned problems, and can eliminate the need for intermittent cutting by forming a tooth-shaped surplus portion on the conical tip of a bevel gear, and at the same time reduce the forming load of the bevel gear. An object of the present invention is to provide a method for forging a bevel gear that does not increase.

[Means for Solving the Problems]

The bevel gear forging method according to claim 1 is such that a material for forming a bevel gear is inserted into a mold in which a tooth profile of the bevel gear is engraved in a molding portion, and the material is sequentially extruded to the tooth profile by forward extrusion. In the bevel gear forging method, in which the bevel gear is filled up and a part of the material is extruded as a surplus into an open part formed in communication with the forming part in front of the forming part of the mold to complete the forming, Of the bevel gear is smaller than the root diameter of the conical tip portion of the bevel gear, and the depth of the tip surface of the material is equal to or higher than the height of the material that has flowed into the opening when the molding is completed. This is to preliminarily form a molding concave space which becomes a concave space.

The bevel gear forging method according to claim 2 is such that a material for forming a bevel gear is inserted into a mold in which a tooth profile of the bevel gear is engraved, and the material is sequentially extruded to fill the tooth profile. A bevel gear forging method for forming a bevel gear, wherein a forming recess space having a shape and a volume such that the material is just filled with the tooth profile portion at the time of completion of forming is previously formed on the tip end surface of the material. Is.

[Work]

In the bevel gear forging method according to claim 1, since the diameter of the open portion is set to be smaller than the root diameter of the conical tip portion of the bevel gear, a tooth-shaped excess portion is not formed in the bevel gear. In addition, since the molding recessed space, which is a recessed space having a depth equal to or higher than the height of the material flowing into the open portion at the time of completion of molding, is previously formed on the tip end surface of the material, the molding load increases. Things will disappear.

In the bevel gear forging method according to the second aspect of the present invention, since the forming recess space having a shape and a volume that allows the material to be filled in the tooth profile portion when the forming is completed is formed in the tip end surface of the material in advance, No excess portion is formed at the tip of the cone.

〔Example〕

 Hereinafter, details of the method of the present invention will be described with reference to the drawings.

FIG. 1 shows a bevel gear forging apparatus used in an embodiment of a bevel gear forging method according to the present invention.
Reference numeral 31 denotes a die having a hole portion 35 into which a material 33 for forming a bevel gear is inserted.

A molding portion 37 is formed in front of the hole portion 35 of the die 31,
A tooth profile portion 39 having a shape corresponding to the tooth profile of the bevel gear to be molded is engraved on the molding portion 37.

As shown in FIG. 2, an open portion 41 having a circular cross section is formed in front of the toothed portion 39 so as to communicate with the forming portion 37.

The diameter of this open portion 41 is the conical tip portion 43 of the bevel gear to be formed.
Is smaller than the root diameter D of

Thus, in this embodiment, the distal end surface 45 of the material 33 is formed with the molding recess space 47 in advance.

The molding recess space 47 has, for example, a truncated cone shape, and has a depth equal to or higher than the height H of the material 33 flowing into the opening 41 at the time of completion of molding, as shown in FIG. It has such a shape and volume that it becomes a concave space 49.

In the figure, reference numeral 51 indicates a punch and reference numeral 53 indicates a knockout pin.

In the bevel gear forging device configured as described above, the material 33
After being housed in the hole 35, the material 51 is sequentially extruded by the punch 51 so as to be filled in the toothed portion 39, and further formed in front of the forming portion 37 of the die 31 as shown in FIG. The bevel gear is forged by extruding a part of the material 33 as the extra thickness 55 into the opened portion 41.

In the bevel gear forging method described above, the diameter of the open portion 41 is set to be smaller than the root diameter D of the conical tip portion 43 of the bevel gear, so that the bevel gear has a tooth-shaped surplus portion. This eliminates the need for intermittent cutting.

Then, at the end surface 45 of the material 33, when the molding is completed, the open portion 41
Since the molding concave space 47 to be the concave space 49 having a depth equal to or more than the height H of the material 33 flowing in the above is formed in advance, the molding load can be reduced.

That is, the forming recess space 47 previously formed in the material 33.
Is gradually compressed as the material 33 is pressed forward by the punch 51 on the molding portion 37, and after the material 33 is filled in all the spaces of the toothed portion 39, when the excess thickness 55 flows into the open portion 41, Since the material 33 is present inside the open portion 41, it is hollow when the material 33 flows into the open portion 41, and the open portion 41 is much lower in load than the solid material 33 flowing into the open portion 41.
Since the material 33 flows out, the forming load of the bevel gear can be significantly reduced as compared with the conventional case.

Further, the variation in the volume of the material 33 is effectively absorbed by the height H of the extra thickness 55 and the volume of the recessed space 49 after molding.

FIG. 4 shows another embodiment of the method for forging a bevel gear according to the present invention. In this embodiment, the die 61 has no specially formed opening, and the tip surface 65 of the material 63 is formed. In addition, when the molding is completed, a molding recess space (not shown) having such a shape and volume that the material 63 is just filled with the tooth-shaped portion 39 is formed in advance and the pressing is performed.

That is, in this embodiment, the molding recess space gradually shrinks by molding to become the recess space 67 as shown in the figure,
No excess thickness is formed at the conical tip of the gear, and intermittent cutting can be dispensed with, and the forming load of the bevel gear can be reduced, as in the above-described embodiment.

In the embodiment described above, the example in which the forming concave space 47 is formed on the side of the material 33 that becomes the conical tip portion 43 of the gear is described, but the present invention is not limited to this embodiment. Of course, for example, as shown in FIG. 5, a recess 71 may be formed on the side opposite to the molding recess space 47.

Further, in the embodiment described above, the example in which the cylindrical material 33 is formed is described, but the present invention is not limited to such an embodiment, and for example, as shown in FIG. It is needless to say that the invention can be applied to the material 75 in which the shaft hole 73 is formed, and in this case, the molding recess space 77 may be formed in a chamfered shape.

〔The invention's effect〕

As described above, in the bevel gear forging method according to claim 1,
Since the diameter of the open portion is set to be smaller than the root diameter of the conical tip portion of the bevel gear, the bevel gear does not have a tooth-shaped excess thickness portion, and intermittent cutting can be unnecessary. Further, since the forming recessed space, which is a recessed space having a depth equal to or higher than the height of the material that has flowed into the open portion at the time of completion of forming, is previously formed on the tip end surface of the material, the forming load is reduced. be able to.

In the bevel gear forging method according to the second aspect of the present invention, since the forming recess space having a shape and a volume that allows the material to be filled in the tooth profile portion when the forming is completed is formed in the tip end surface of the material in advance, There is no advantage that a surplus part is not formed at the tip of the cone, intermittent cutting is unnecessary, and the forming load of the bevel gear can be reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a bevel gear forging apparatus used in an embodiment of a bevel gear forging method according to the present invention. FIG. 2 is a transverse sectional view taken along the line II-II in FIG. FIG. 3 is a longitudinal sectional view showing a state at the end of forming by the bevel gear forging device of FIG. FIG. 4 is a vertical sectional view showing a bevel gear forging apparatus used in another embodiment of the bevel gear forging method according to the present invention. FIG. 5 and FIG. 6 are vertical sectional views showing other material shapes used in the bevel gear forging method of the present invention. FIG. 7 is a vertical sectional view showing a conventional bevel gear forging device. FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. FIG. 9 is a longitudinal sectional view showing a state at the end of molding by the bevel gear forging apparatus of FIG. 7. [Explanation of symbols of main parts] 31,61 …… Die (die) 33,63 …… Material 37 …… Molding part 39 …… Tooth profile 41 …… Open part 43 …… Cone tip 45,65… … Tip surface 47 …… Recessed space for molding 49, 67 …… Recessed space 51 …… Punch.

Claims (2)

[Claims] 1. A material for forming a bevel gear is inserted into a mold in which a tooth portion of a bevel gear is engraved in a molding portion, and the material is sequentially extruded to fill the tooth portion, and further, In the bevel gear forging method in which a part of the material is extruded as a surplus to an open portion formed in communication with the forming portion in front of the forming portion of the mold to complete the forming, a diameter of the opening portion is set to bevel gear. The diameter of the root of the conical tip is smaller than that of the conical tip, and at the time of completion of the forming, a forming concave space which becomes a concave space equivalent to the height of the material flowing into the open portion is formed in advance at the end surface of the material. A bevel gear forging method. 2. A bevel gear is formed by inserting a material for forming a bevel gear into a mold in which a tooth profile of the bevel gear is carved in a molding portion, and by sequentially extruding this material into the tooth profile. In the forging method of a bevel gear to be molded, a molding recess space having a shape and a volume such that the material is just filled in the tooth profile when the molding is completed is formed in advance on the tip end surface of the material. How to forge bevel gears.