JPH04210840A - Method for forging spiral gear or the like - Google Patents

Abstract

PURPOSE:To provide efficient manufacturing method for spiral gear, etc., in low cost by forming plural recessed parts or projection parts for engaging a die knock-out to a circular burring part at the center part of a raw material. CONSTITUTION:The raw material W is hot-forged with an upper and lower die blocks 3, 2 in a die 1 for forging tooth form. In such a manner, after forming outer shape and tooth form to the raw material W, while rotating the formed raw material W with the die knock-out 6, this is released from the die and the forging to the spiral gear, etc., is executed. Then, plural projection parts 12 or recessed parts for engaging the die knock-out are formed to the circular burring part at the center part of raw material W. The die 5 in the lower die block 2 and a punch 13 in the upper die block 3 are provided and the raw material W is formed between both 5, 13. By this method, the formed raw material is surely and smoothly released from the die and it is no fear that deformation, etc., of formed teeth is generated.

Description

[Detailed description of the invention]

[00011

[Field of Industrial Application] The present invention relates to a forging method for reliably and properly releasing a molded material in a manufacturing method in which a spiral gear or the like is molded using a forging die. [0002] [0002] For example, differential gears used in power transmission mechanisms of automobiles or agricultural equipment use bevel gears such as spiral bevels, staggered shaft gears such as hypoid gears, etc. Conventionally, the gear portion of such a spiral gear is generally manufactured by cutting a blank formed by forging or rolling using a special gear cutting machine such as Gleason. On the other hand, some literature and report examples have been introduced in which gear parts such as bevel gears are formed by precision forging, and they are mainly introduced as being easy to apply to gears with straight tooth traces such as straight bevel gears. . [0003]

[Problem to be solved by the invention] However, when machining is carried out using a special gear cutting machine as in the past, the gear cutting machine is expensive, and especially in recent years, for example, with the trend toward high-end products, it is difficult to obtain high output. When forming components into automotive parts, it is necessary to repeat various processes to improve tooth contact in order to reduce noise and vibration, improve durability, etc., which reduces manufacturing costs. There was a problem that it took a while. Therefore, if it can be manufactured using precision forging, which is being researched in some areas,
Various processes can be reduced and it is advantageous in terms of cost. However, when trying to form, for example, a spiral gear with an undercut tooth surface on one side of the tooth profile by forging, the tooth profile formed on the material and the mold are lost during demolding. A problem arose in that the tooth molds of the molded teeth interfered and deformed the molded teeth, and a means was needed to release the mold while reliably avoiding this interference. [0004]

[Means for Solving the Problems] In order to solve the problems, the present invention forges a gear material with a die, molds the outer shape and tooth profile, and then releases the molded material while rotating it by die knockout. In the method for forging spiral gears, etc., a plurality of recesses or projections for die knockout engagement are formed in a circular burr at the center of the material. [0005]

[Operation] By engaging the die knockout with the plurality of concave or convex portions formed in the circular burr at the center of the material, the rotation of the die knockout is reliably transmitted to the material during demolding, and the molded material is prevented by interference etc. The tooth profile formed in this way will not be deformed. The circular burr in the center will be removed in a later process. [00061

[Example] An example of the method for forging spiral gears, etc. of the present invention will be described based on the attached drawings. 1 to 3 are state diagrams showing the process of tooth forming using a tooth-forming forging die, and FIG. 4 is a plan view of the die knockout. Before explaining the method for forming spiral gears and the like of the present invention, a die for tooth profile forging will first be explained based on FIG. 1. The tooth profile forging die 1 includes an upper die 3 that opens and closes by moving up and down relative to the lower die 2.
The material W positioned between the two is processed by hot forging. The lower mold 2 includes a die 5 provided on a die holder 4 and a die knockout 6 provided in the center, and the die 5 has a ring-shaped forging tooth profile 7 formed therein. [0007] The tooth profile 7 of the die 5 has a spiral tooth trace in order to form a finished material W as shown in FIG. 7, for example a spiral bevel gear, and as shown in FIG. The surface 8 has an undercut shape and is tapered back by a required amount t. Incidentally, such a forged tooth pattern 7 of the die 5 is formed with high precision by, for example, electrical discharge machining. [0008] On the other hand, the die knockout 6 can be freely raised and lowered by a knockout bin 9 located below, and a plurality of outer circumferential ribs 10 are provided on the outer periphery of the die knockout 6 in a circumferential direction, and are provided on the die holder 4. It engages with the lead groove 11. Since the outer ring 10 and the lead groove 11 are inclined vertically, the die knockout 6 lifted by the knockout bin 9 rises while rotating around the vertical central axis. Further, the direction of this inclination is such that the forming material W rotates toward the undercut tooth surface 8 side of the forged tooth die 7, as shown in FIG. Of course, the relationship between the outer peripheral rib 10 and the lead groove 11 may be reversed, that is, the lead groove may be provided on the outer periphery of the die knockout 6, and the rib may be provided protrudingly on the die holder 4 side. On the other hand, a plurality of engaging convex portions 12 are provided on the upper peripheral edge of the die knockout 6 in the circumferential direction. That is, for example, as shown in FIG. 4, four engagement protrusions 12 are provided at equal intervals on the circumference, and the engagement protrusions 12 form recesses Wo in the material W and engage the two. The molding material W is rotated when the die knockout 6 rotates. The shape of the engaging convex portions 12 is not limited to a convex shape, but may be a concave shape, and it goes without saying that four or more engaging convex portions 12 may be provided. On the other hand, the upper mold 3 has a punch 13 having a molding part 14 on the lower surface.
As mentioned above, the mold is opened and closed by moving up and down. [00101 A method for forging a spiral gear etc. with the above configuration is as follows. First, a disk-shaped material cut out from a material is roughly formed and positioned on the lower die 2 of FIG. The shape of the material W at this time may be one with a hole pre-drilled in the center as shown in Figure 1, or may be one without any holes, but it is better to drain water from the beginning. This is more preferable since it can reduce the pressure. [0011] This molding is performed, for example, by heating the material W to about 1150°C.
It is hot forging performed by heating to a degree of 1000 to 15
The forging is performed at a forging pressure of 00 tons. Then, on the bottom surface of the material W,
The tooth profile formed by the forged tooth profile 7 and the engagement protrusion 12 form the recess WO (
5) is formed, and the punch forming part 14 is formed on the upper surface of the material W.
The molding is done by Recessed portion W formed by this engaging convex portion 12
o is formed in the burr W1 on the inner peripheral edge of the material, as shown in FIG. The burr W1 has an annular shape along the edge of the six layers when the material has been drained in advance, and has a solid disc shape when the material has not been drained. This burr W1 is then cut off in the final step. In addition, FIG. 7 shows the recess W
This is an example in which molding is performed using a mold provided with eight retaining convex portions 12. [0012] Next, as shown in FIG. 3, when the punch 13 rises, the knockout bin 9 moves upward, and the die knockout 6
is raised while rotating due to the engagement between the outer circumferential rib 10 and the lead groove 11. Therefore, the molding material W also rises while rotating due to the engagement between the engagement protrusion 12 and the recess WO. Since the direction of rotation is in the direction of the acida cut tooth surface 8 of the tooth profile 7 in FIG. There is no risk of deformation of the molded teeth. Then, this forming material W undergoes another forging process and the like to improve the tooth profile accuracy and become a finished product. [0013] The forging method of the present invention as described above can be applied not only to spiral bevel gears but also to hypoid gears and the like, and the shape of the engaging protrusion 12 is not limited to a convex shape, but can also be a concave shape. It can also be a shape. [0014]

Effects of the Invention As described above, the forging method of the present invention enables the forging of spiral gears, which has conventionally been difficult due to problems such as mold releasability, to be performed by rotating the material by forming four or convex portions on the burr portion of the material. The solution was to release the mold while the process was in progress, providing an inexpensive and efficient manufacturing method in place of the conventional gear cutter.

[Brief explanation of the drawing]

[Figure 1] Diagram of the opening state of a tooth-shaped forging die

[Figure 2] Diagram of the closed state of the tooth-shaped forging die

[Figure 3] Diagram of the release state of the tooth profile forging die

[Figure 4] Plan view of die knockout

[Figure 5] Recess formed in the burr part of the material

[Figure 6] Partially enlarged sectional view showing the relationship between the tooth profile of the mold and the tooth profile of the material

[Figure 7] Perspective view of molding material

[Explanation of symbols]

1　Tooth profile forging mold 2 Lower mold 3 Upper mold 6 Die knockout 12 Engagement protrusion W Material W○ recess Wl Burr part

Claims (1)

[Claims] [Claim 1] A method for forging a spiral gear, etc., in which a gear material is forged in a die, an external shape and a tooth profile are formed, and then the molded material is released from the mold while being rotated by a die knockout. A method for forging spiral gears, etc., characterized by forming a plurality of concave portions or convex portions for die knockout engagement in a circular burr portion at the center of the material.