JPS6153142B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a ring gear with a small wire diameter, such as a ring gear for an automobile, and in particular, the present invention relates to a method for manufacturing a ring gear with a small wire diameter, such as a ring gear for an automobile, and in particular, a method for manufacturing a ring gear with a narrow wire diameter, such as a ring gear for an automobile. The present invention relates to a ring gear forging method in which a material is forged with a taper punch so that the diameter of the material is expanded from the inner periphery to form a tooth profile on the outer periphery.

As shown in FIGS. 1 and 2, in the conventional gear forging method in which the tooth profile 3 formed on the die 2 is filled with the material 5, the tooth 7 adjacent to one side of the tooth trace
The molded gear 6 is molded with an excess portion 9 or a large amount of burr that connects each other. Therefore, the forging force inevitably increases, a forging machine with a large capacity is required, and the life of the die is inevitably shortened.
Further, a lot of machining is required, such as cutting off the excess thickness 9 after forging, and there is a lot of wasted material.

In addition, the conventional method of applying an axial rolling load to the material and increasing the outer diameter of the material to form a tooth profile on the outer periphery requires a high heading ratio, especially for ring gears with a small wire diameter, making it difficult to form the tooth profile. It was extremely difficult. Therefore, when the material is heated to a high temperature and hot forged in order to improve its fluidity, it not only causes roughness but also has the drawback that the desired tooth precision cannot be obtained.

Therefore, the present invention has been devised to eliminate such drawbacks of the prior art, and aims to provide a forging method that can form a highly accurate and strong tooth profile on the outer periphery of a ring-shaped material with a small forming force. do.

A feature of the present invention is that a lower mold having a tooth profile for tooth forming formed on the inner periphery is fixed on a machine base plate, and a ring-shaped material is inserted into the inner peripheral position of the tooth profile of the lower mold. After constraining the top and bottom of the material, a punch with a conical outer peripheral surface that gently slopes toward the tip is press-fitted into the inner periphery of the material, thereby converting the downward movement of the punch into an expanding movement in a plane perpendicular to the punch axis. In other words, the punch acts like a wedge,
The purpose is to expand the material diameter of the ring-shaped material from the inner circumferential side and press the outer periphery of the material against the tooth profile, thereby forming completed teeth on the outer periphery of the ring-shaped material.

The ring-shaped material 30 used to form the ring gear 31 partially shown in FIG. 3 is made by winding a steel wire formed into a predetermined cross-sectional shape by drawing or rolling to obtain a desired diameter. 4 and 7 by welding the abutted surfaces.

FIG. 4 shows a cross section of the main part of the forging device, with the left half showing a state in which the ring-shaped material 30 is attached, and the right half showing a state in which the upper die ring 38 is lowered. The upper mold ring 38 has a substantially cylindrical shape and has a shoulder end face 28 extending horizontally at its lower tip, and an outer circumferential tooth mold 29 having a tooth profile formed on its upper outer periphery. This upper mold ring 38 is
It is connected to a ram (not shown) of a forging device, and is mounted so as to be able to reciprocate and face the upper surface of the machine base plate 11.

Reference numeral 26 denotes a punch disposed on the inner periphery of the upper mold ring 38, and a truncated conical guide portion 27 is provided on the outer periphery on the distal end side of the punch, which is inclined at a gentle taper angle θ toward the distal end.

This punch 26 is also connected to a ram (not shown) of the forging device, and is mounted so as to be able to reciprocate independently of the upper die ring 38, facing the upper surface of the machine base plate 11.

A die 18 is fixed to the upper surface of a machine base plate 11 of a forging device with a pressure receiving plate 13 and a spacer ring 22 interposed therebetween by a tightening ring 21.

The die 18 has a tooth profile 19 on the inner periphery for forming teeth on the outer periphery of the ring-shaped material 30, and
It is fixed on the same axis as 6.

Reference numeral 14 denotes a knockout, which is provided facing the tip of the punch so as to be movable back and forth in the axial direction of the punch 26. A pressure receiving plate 13 is disposed above the knockout, and a cylindrical knockout 15 is disposed above the pressure receiving plate 13.

12 is a pressure receiving ring.

A meshing tooth profile 20 is formed on the outer periphery of the knockout ring 15, and the meshing tooth profile 20 engages with the tooth profile 19 on the inner periphery of the die 18 without a gap. forms the bottom surface 16 (FIG. 7) of the tooth preparation space. The knockout ring 15 is configured to move back and forth in the tooth forming space in the axial direction while remaining engaged with the tooth profile 19 as the knockout 14 moves up and down.

On the other hand, an upper die ring 38 provided on the outer periphery of the punch 26
When the upper die ring 38 is lowered, it engages with the tooth profile 19 of the die 18 with almost no gap, and in this state, the lower surface of the outer circumferential tooth profile 29, that is, the shoulder end surface 28 forms the die engraving upper surface (FIG. 8) of the tooth forming space. do.

Next, the dimensional relationship between the inner and outer diameters of the material, the inner diameter of the tooth profile 19, the inner diameter of the knockout ring 15, etc. will be explained.

The inner diameter of the upper inner edge 37 of the knockout ring 15 is formed to be approximately equal to the inner diameter of the desired ring gear 31.

Further, the upper die ring 38 is also formed so that its inner diameter is approximately equal to the inner diameter of the desired ring gear 31. The ring-shaped material 30 has an outer diameter of the die 18.
The inner diameter of the knockout ring is slightly smaller than the inner diameter of the tooth profile 19, and the inner diameter is considerably smaller than the inner diameter of the upper inner circumferential edge 37 of the knockout ring. The upper inner edge of the knockout ring 37 is located on the lower edge of the inner circumference of the material 30 adjacent to the upper inner edge of the knockout ring.
It has a chamfered portion 32 whose peripheral edge is cut out to a diameter position considerably larger than the inner diameter of 7.

Further, the diameter of the outer periphery of the conical punch guide portion 27 is smaller than the inner diameter of the ring-shaped material 30, and the diameter of the outer periphery of the upper end thereof is equal to or slightly smaller than the inner diameter of the upper edge 37 of the inner periphery of the knockout ring. Molded small.

Next, the operation of the device with the above configuration will be explained using the ring-shaped material 3.
This will be explained along with the process of forming a tooth profile on the outer periphery of 0.

First, as shown on the left side of FIG.
Insert it into the inner peripheral side of the tooth profile 19 of No.8. At this time, the material 30 is
Since the chamfered portion 32 is formed on the lower periphery of the inner periphery, the knockout ring 15 contacts the bottom surface 16 of the die at a position on the outer periphery side of the inner periphery upper edge 37 of the knockout ring 15.

Next, as shown on the right side of Fig. 4, the upper mold ring 3
8 and lower the shoulder end surface 2 at the tip as shown in Figure 8.
8 is brought into contact with the upper surface of the material 30. At this time, the outer peripheral tooth profile 29 of the upper mold ring 38 descends while engaging with the tooth profile 19 of the die 18. Upper mold ring 3
8 has its lowered end set by, for example, a stopper 42, and after being lowered, it is kept at that lowered position until the molding is completed.

Next, as shown on the left side of FIG. 5, the punch 26 is lowered to allow the guide portion 27 to enter the inner periphery of the material 30. As a result, the conical surface of the punch guide portion 27 acts like a wedge, expanding the material diameter of the ring-shaped material 30 in the radial direction from the inner circumferential side as shown in FIG. Tooth profile 1
Press it to 9.

As a result, the outer peripheral side of the material 30 has a shoulder end surface 28
and the bottom surface 16 of the die are pressed into the space within the tooth profile which is closed at the top and bottom.

At this time, the chamfered portion 32 on the lower periphery of the inner circumference of the material becomes smaller as the material swells toward the space between the upper inner periphery edge 37 of the knockout ring and the surface of the guide portion 27 as the punch 26 descends. Become.
However, since the distance between the inner circumferential upper edge 37 and the surface of the guide portion 27 is also relatively small, the material 30 does not enter between the knockout ring 15 and the punch 26.

Eventually, when the punch 26 descends to a predetermined position as shown on the right side of FIG. 5, the gap between the inner upper edge 37 of the knockout ring 15 and the outer periphery of the punch guide portion 27 becomes very small as shown in FIG. At the same time, the gap between the lower inner peripheral edge 45 of the upper mold ring 38 and the outer periphery of the punch guide portion 27 also becomes minute.

In this way, the material 30 is pressed into the nearly sealed die-cutting space by the conical punch 26, filling the space and almost perfectly shaping the ring gear.

When the molding is completed, the upper die ring 38 and punch 26 rise first as shown on the left side of FIG. 6, and then the knockout ring 15 rises as shown on the right side of FIG.
is raised to push up the molded ring gear 31.

The ring gear 31 formed in this way is
Unlike ring gears formed by conventional ring gear forging methods, there are no unformed portions or large burrs that interconnect adjacent teeth on one side of the tooth trace. In other words, instead of rolling the material in the axial direction to form teeth on the outer periphery of the material, as in the past, the material is expanded radially within the space of the tooth forming part whose outer periphery and upper and lower sides are sealed, and teeth are formed on the outer periphery of the material. Because it is molded, teeth with smooth material flow, good flow connection, and excellent strength, like rolled gears, are molded.
Moreover, since there is no strain on the flow of the material around the outer periphery of the material, not only is it possible to cold forge the ring gear, but the tooth profile 19 of the die 18 is less worn. The wear of the mold is rather due to the guide portion 27 of the punch 26.
Although the wear of the guide portion 27 is greater, the wear of the guide portion 27 has little effect on molding accuracy, so there is no problem in mass production of ring gears.

Although there are many other possible forging devices and material cross-sectional shapes in addition to the above embodiments, an example of the forging device will be described below.

FIG. 11 shows that when the punch 126 is lowered, the punch 126 is attached to the upper mold ring 138 that was lowered in advance.
This represents an example in which a rolling load is finally applied to the material 130 in the axial direction by rear-end collision, and the symbols in the figure are indicated by adding 100 to the locations corresponding to the symbols of the example in FIG. 4. has been done.

In this embodiment, a double-acting hydraulic press is used as the forging device, and a pressure-receiving surface 144 is formed at a suitable location on the inner periphery of the upper die ring 138, and a stepped end surface 143 is provided on the punch 126 in correspondence with the pressure-receiving surface 144.

As a result, as shown on the right side of FIG. 11, the material 130 is surrounded in the vertical direction by the shoulder end surface 128 of the upper die ring 138 and the stamping bottom surface 116 of the knockout ring 115, and its inner and outer peripheries are punched. The outer peripheral surface of the guide portion 127 of 126 and the die 1
When surrounded by the surface of the tooth profile 119 of 18, the step end face 143 collides with the pressure receiving surface 144, and the upper mold ring 138 receives the downward load of the punch 126 and transmits the rolling load in the axial direction to the material 130. The blank 130 is thus finally pressed into a substantially sealed die-cutting space, further ensuring filling of the space.

In this case, a stopper at the lower end of the upper mold ring 138 is not particularly provided, and the upper mold ring 138 is always pressed against the upper surface of the material by hydraulic pressure during lowering.

As described above, the present invention restrains the upper and lower sides of a ring-shaped material with a special cross-sectional shape inserted into the inner periphery of the tooth profile of the die, and also uses the wedge action of the gently conical tapered surface on the outer periphery of the punch to wedge the ring-shaped material. Since the completed tooth is formed on the outer periphery of the material by expanding in the outer radial direction, a highly accurate and strong tooth profile can be formed on the outer periphery of a pre-prepared ring-shaped material with a thin wire diameter with a small forming force. Since burrs do not occur during the early and middle stages of the punch's descent, and the material is forged in a nearly sealed state with no excess metal in the later stages, it is possible to form a highly accurate ring gear with minimal burrs and excess thickness. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional ring gear forging method.
FIG. 2 is an explanatory cross-sectional view of a ring gear forged by the method shown in FIG. 1. FIG. 3 is a partially enlarged perspective view of the ring gear. FIG. 4 to FIG. 6 are explanatory diagrams showing an embodiment of the present invention and showing the molding process step by step. FIGS. 7 to 10 are explanatory diagrams showing enlarged portions of the molding process shown in FIGS. 4 and 5. FIGS. FIG. 11 shows a different embodiment from FIG. 4 and is an explanatory diagram of a forging device. (Explanation of symbols), 11... Machine base plate. 15...
Notsuku out ring. 16...Bottom surface of die carving. 17
...lower mold. 18... Dice. 19...Tooth shape. 23
...upper mold. 26...Ponchi. 27...Information part.
28... Shoulder end surface. 30...Material. 31...Ring gear. 32... Chamfered portion. 33...molded teeth. 3
8... Upper mold ring. θ...Taper angle.

Claims (1)

[Claims] 1. A ring-shaped material with a chamfer formed at least on the lower side periphery of the inner periphery is placed at the inner periphery position of the tooth profile of the lower mold, which is fixed on the machine surface plate and has a tooth profile for tooth forming formed on the inner periphery. Next, a cylindrical upper die ring, which faces the upper surface of the machine surface plate and reciprocates on the same axis as the lower die, and has an outer peripheral tooth profile that meshes with the tooth profile formed on the outer periphery, is placed on the upper surface of the material. Then, lower the inner periphery of the upper mold ring to face the upper surface of the machine surface plate and lower the punch that reciprocates on the same axis as the lower mold. A conical guide portion formed on the outer periphery of the punch tip and gently sloping toward the tip is press-fitted into the inner periphery of the ring-shaped material, thereby expanding the ring-shaped material from the inner periphery toward the outer diameter. A forging method for forming a tooth profile on the outer periphery of a ring-shaped material.