HK1048783A1

HK1048783A1 - Method of manufacturing ring gear

Info

Publication number: HK1048783A1
Application number: HK03101061A
Authority: HK
Inventors: 饭塚博
Original assignee: 株式会社饭塚制作所
Priority date: 2001-01-10
Filing date: 2003-02-14
Publication date: 2003-04-17
Also published as: JP3418180B2; HK1048783B; TW544351B; CN1364668A; CN1166473C; JP2002205137A

Abstract

This invention provides a manufacturing method of a ring gear which has short manufacturing time, is excellent in yield of the material, and is capable of reducing the manufacturing cost. A first intermediate product is obtained by forming a bottomed hole having internal teeth on the inner circumference by forging a material. Next, a second intermediate product is formed by punching a hole bottom of the bottomed hole having the internal teeth by a press to form a hole having the internal teeth. Then, a punch is used to perform punching operation on the second intermediate product. In the punching operation, the second intermediate product is fitted in a setting groove part of a fitting groove of a die, and the pressure is applied to an upper part of the second intermediate product by the punch to form recesses in an outer circumferential part of the second intermediate product by a blade part, and to form the ring gear with a part between the recesses forming an arm and having internal teeth.

Description

Method for manufacturing toothed ring

Technical Field

The invention relates to a method for producing a toothed ring for a vehicle safety belt mechanism.

Background

As a prior art ring gear used for a seat belt mechanism of an automobile, a ring gear is known which has a hole with internal teeth on an inner periphery thereof and a shank on an outer periphery thereof, as shown in the figure. This ring gear 4 is used to wind up the seat belt in the event of a collision accident or the like. That is, a pinion 32 is provided on a roller 31 on which a webbing is wound by a coil spring winding mechanism, and the pinion 32 is disposed in the hole 2 of the ring gear 4. Since the ring gear 4 is fixed to a base supporting the roller 31 rotatably by the pin 33, the internal teeth 3 of the ring gear 4 are not meshed with the external teeth 35 of the pinion gear at ordinary times. However, when receiving an impact due to a collision or the like, gunpowder provided at one end of the guide tube 34 explodes, and steel balls (not shown in the drawings) are ejected from the guide tube 34. The steel balls collide with the shank 1 provided protrudingly on the outer periphery of the ring gear 4, and the ring gear 4 is rotated while cutting the pin 33 that fixes the ring gear 4. Thereby, the internal teeth 3 of the ring gear 4 mesh with the external teeth 35 of the pinion gear 32, and the webbing is wound up and driven.

In the conventional technique, the ring gear 4 is manufactured by the process shown in fig. 10a to 10 d. That is, as shown in fig. 10a, after the blank 30 is inserted into the die 36, pressure is applied to the blank 30 in the direction of the arrow in fig. 10a to plastically deform the blank 30, thereby forming a first intermediate product 38 having a protrusion 37 on the outer periphery. In this case, the inclined portion 40 for retraction of the material 30 at the time of forming is formed on the blade portion 39 of the die 36, and in order to ensure such retraction, the material 30 to be used must be thicker than the final product.

Then, the first intermediate product 38 is cut by cutting the E portion indicated by the cross hatching of fig. 10b to obtain a second intermediate product. In this cutting process, the portion that ensures the aforementioned escape of the first intermediate product 38 is cut away.

Then, as shown in fig. 10c, the second intermediate product is cut to form the hole 2 and the protrusion 37 is cut into a predetermined shape, thereby obtaining a third intermediate product 41 having the shank 1 on the outer periphery.

Next, as shown in fig. 10d, internal teeth 3 are formed on the inner periphery of the hole 2 of the third intermediate product 41 by broaching. Finally, a pin hole machining (not shown) is performed to obtain the ring gear 4.

However, in the above-described conventional example, the internal teeth are formed by a plurality of times of cutting and broaching, and therefore, there is a problem that the manufacturing time is long. Further, since the blank 30 needs to be thick, there is a problem that the material utilization efficiency is low and the manufacturing cost is high.

Disclosure of Invention

In view of the above-described problems, an object of the present invention is to provide a method for manufacturing a ring gear having a hole with internal teeth on an inner periphery thereof and a protruding shank on an outer periphery thereof in a short manufacturing time with high yield.

That is, the method for manufacturing a ring gear of the present invention comprises:

a step of forging the blank to form a bottomed hole having internal teeth on the inner periphery thereof to obtain a first intermediate product,

a step of punching the hole bottom of the hole with the bottom of the first intermediate product by a press machine to form a hole with internal teeth on the inner periphery to obtain a second intermediate product,

a step of blanking the second intermediate product by a blanking device,

wherein the blanking device is provided with a die and a blanking punch head,

the die comprises a sleeve having an insert groove, and fitted in the insert groove so as to be movable up and down, and a guide body disposed in the insert groove,

the embedding groove comprises an assembly groove part with the same inner circumference shape as the outer circumference shape of the second intermediate product at the upper part and a forming groove part with a blade part protruding from the inner wall at the lower part,

the sleeve has an outer peripheral shape identical to an inner peripheral shape of the forming groove portion, and sleeve teeth provided on an inner periphery have an identical shape to inner teeth of the second intermediate product, the guide body has a cross section having an identical shape to a hole in which the inner teeth of the second intermediate product are provided, and guide teeth capable of meshing the inner teeth and the sleeve teeth are formed on an outer peripheral portion,

the punching punch has an outer peripheral shape identical to the inner peripheral shape of the forming groove portion, and has an escape groove formed on the outer periphery,

moreover, the blanking process includes:

a step of projecting the upper portion of the guide body from the sleeve in a state where the guide teeth of the guide body are engaged with the sleeve teeth of the sleeve, fitting the upper portion of the guide body into the hole of the second intermediate product so that the inner teeth of the second intermediate product are engaged with the guide teeth, and disposing the second intermediate product in the fitting groove portion of the fitting groove,

a step of moving the punching punch, which is positioned so that the retreat groove portion of the punching punch engages with the blade portion of the forming groove portion, applying pressure to the second intermediate product, forming a plurality of concave portions on the outer periphery of the second intermediate product by the blade portion, and obtaining a ring gear in which the portion between the concave portions constitutes the shank portion,

and moving the sleeve to push the gear ring to take out the gear ring from the mold.

According to the above method, in the process of manufacturing the ring gear having the hole provided with the internal teeth and the shank formed on the outer periphery, the forging, the punching and the blanking are only required in addition to the cutting step of the finishing process, so that the ring gear can be manufactured in a short time without the time-consuming broaching process of the conventional art, and the manufacturing cost can be greatly reduced.

Further, since the punching process is performed by applying pressure by the punching punch in a state where the internal teeth provided in the hole of the second intermediate product are engaged with the guide teeth of the guide body and positioned, the concave portion can be formed in the second intermediate product with high accuracy. That is, in the punching process, the inner wall of the fitting groove prevents the blank from retreating in the outer direction of the second intermediate product, and the guide prevents the blank from retreating in the inner direction of the second intermediate product, so that the punching waste is discharged only from the retreat groove portion provided on the outer periphery of the punching punch, and therefore, the punching process can be performed with high accuracy.

Further, by positioning the blade portion of the die in meshing engagement with the outer periphery of the sleeve, positioning the sleeve teeth of the sleeve in meshing engagement with the guide teeth of the guide body, and further positioning the guide teeth of the guide body in meshing engagement with the internal teeth of the second intermediate product, it is possible to perform accurate punching processing in a positional relationship (phase) defined by design between the internal teeth in the hole of the ring gear as a final product and the shank portion of the outer periphery.

In particular, since the guide body serving as a member for preventing the blank from retreating during the punching process and the sleeve serving as a member for ejecting the obtained product and taking out the product from the die can be used as the positioning member during the punching process, the punching apparatus can be made to have a refined and simple structure.

Thus, according to the present invention, although this is a comparatively simple method using a punching apparatus having a comparatively simple structure, it is possible to manufacture a ring gear with extremely high accuracy at high efficiency.

Further features of the invention and its attendant advantages will be more clearly understood by the following description of the best mode for carrying out the invention with reference to the accompanying drawings.

Drawings

Fig. 1a to 1e are explanatory views showing a method of manufacturing a ring gear according to a preferred embodiment of the present invention;

fig. 2a and 2b are a plan view and a cross-sectional view, respectively, of a toothed ring manufactured by the method shown in fig. 1;

FIG. 3 is a sectional view showing a forging apparatus using the method shown in FIG. 1;

fig. 4 is an explanatory view showing a punching apparatus using the method shown in fig. 1;

FIG. 5 is a sectional view A-A of FIG. 4;

FIG. 6 is a cross-sectional view B-B of FIG. 4;

FIG. 7 is a cross-sectional view C-C of FIG. 4;

FIG. 8 is a cross-sectional view D-D of FIG. 4;

FIG. 9a is a cross-sectional view of the blade; FIG. 9b is a cross-sectional view of the sleeve; FIG. 9c is a cross-sectional view of the guide body; FIG. 9d is a cross-sectional view of the punch; fig. 9e is a cross-sectional view of the blanking scrap;

FIGS. 10a to 10d are explanatory views showing a method of manufacturing a ring gear according to the prior art;

fig. 11 is an explanatory view showing a state of use of a conventional ring gear.

Detailed Description

Hereinafter, a method of manufacturing a ring gear according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The ring gear 4 of the present embodiment has internal teeth 3 on the inner periphery and a plurality of shanks (projections) 1 on the outer periphery, and is used in an automobile seatbelt mechanism, and is manufactured in the order shown in fig. 1a to 1e, for example.

First, a blank (workpiece) 30 shown in fig. 1a is forged to produce a first intermediate product 5 having a bottomed hole 2a with internal teeth 3 formed on the inner periphery thereof as shown in fig. 1 b. To obtain such a first intermediate product 5, for example, as shown in fig. 3, a disk-shaped blank 30 is fitted into the forging die 20. Then, the workpiece is forged by a punch 22 having a protrusion 21 for tooth forming provided on the outer periphery thereof, thereby obtaining a first intermediate product 5 shown in fig. 1 b. This process of obtaining the first intermediate product 5 is a forging process. In fig. 3, numeral 23 denotes a release liner, and after the first intermediate product 5 is processed, the release pin 24 is raised, and the first intermediate product 5 is taken out from the forging die 20 by the release liner 23.

Next, the bottom 19 of the hole of the bottomed hole 2a of the first intermediate product 5 is pressed by a press to form the through-hole 2 having the internal teeth 3 on the inner periphery. Thereby, a second intermediate product 6 shown in fig. 1c is obtained. This process of obtaining the second intermediate product 6 is a stamping process.

Then, the second intermediate product 6 is subjected to a punching step to produce a ring gear 4 having internal teeth 3 on the inner periphery and a plurality of shank portions 1 protruding on the outer periphery as shown in fig. 1d, 2a, and 2 b. Such a punching step can be performed by a punching apparatus shown in fig. 4, for example.

This punching apparatus is mainly composed of a die (die)7 and a punching punch 12, and a die 7 is formed with an insert groove 11 opened upward. The upper part of the fitting groove 11 forms an assembly groove 8, and the lower part thereof forms a molding groove 10 communicating with the assembly groove 8.

The fitting groove 8 has an inner peripheral shape identical to the outer peripheral shape of the second intermediate product 6. The vertical length of the mounting groove 8 is set to be larger than the vertical (height) length of the second intermediate product 6. On the other hand, the forming groove portion 10 has a plurality of blades 9 projecting from the inner wall thereof. Fig. 9a shows a cross-sectional view of the blade 9.

In fig. 4, numeral 13 denotes a vertically movable sleeve which is fitted into the groove portion 11 for fitting. As shown in fig. 5, the sleeve 13 has an outer peripheral shape identical to the inner peripheral shape of the forming groove 10, and an inner peripheral shape identical to the inner teeth 3 provided in the hole of the second intermediate product 6. That is, an engagement groove 26 that engages with the blade 9 is formed on the outer periphery of the sleeve 13, and sleeve teeth 15 are formed on the inner periphery of the sleeve 13. The sleeve 13 can be moved up and down in the embedding groove 11 by driving the release pin 25. Fig. 9b shows a cross-sectional view of the sleeve 13.

In fig. 4, reference numeral 16 denotes a guide body disposed in the center of the insert groove 11 of the mold 7. As shown in fig. 6, the guide body 16 has a cross section having the same shape as the hole 2 in which the tooth portion 3 of the second intermediate product 6 is provided, and a guide tooth 14 engageable with the tooth portion 3 of the second intermediate product 6 and the sleeve tooth 15 of the sleeve 13 is formed on the outer peripheral portion. The lower end of the guide body 16 is held by the bottom of the fitting groove 11. Fig. 9c shows a cross-sectional view of the guide body 16.

As shown in fig. 5, the guide teeth 14 are engaged with the sleeve teeth 15 of the sleeve 13, and the engagement groove 26 of the sleeve 13 is engaged with the blade 9, whereby the blade 9, the sleeve 13, and the guide body 16 are positioned relative to each other. Further, the sleeve 13 is slidable in the vertical direction while maintaining the positioning state with the blade 9 and the guide 16.

The punching punch 12 has the same outer peripheral shape as the inner peripheral shape of the forming groove 10. That is, as shown in fig. 8, the relief groove portion 17 having the same outer peripheral shape as the blade portion 9 protruding from the inner wall of the forming groove portion 10 is provided on the outer peripheral surface of the punching punch 12. Accordingly, when the retreat groove portion 17 is engaged with the blade 9, the blade 9 and the retreat groove portion 17 are positioned relative to each other. Fig. 9d shows a sectional view of the blanking punch 12.

The punching process of the present invention is performed as follows by using the punching apparatus described above. Fig. 5 to 8 are sectional views taken along line a-a, line B-B, line C-C and line D-D in fig. 4, respectively.

First, the second intermediate product 6 is placed in the fitting groove 8 of the insert groove 11 of the mold 7. That is, in a state where the guide teeth 14 of the guide body 16 are engaged with the sleeve teeth 15 of the sleeve 13, the upper portion of the guide body is projected from the sleeve, and the upper portion of the guide body 16 is fitted into the hole 2 of the second intermediate product 6 so that the guide teeth 14 of the guide body 16 are engaged with the internal teeth 3 of the second intermediate product 6.

After the blanking punch is positioned so that the relief groove 17 of the blanking punch 12 engages with the blade portion 9, the upper portion of the second intermediate product 6 is pressed by the blanking punch 12 while the second intermediate product 6 is positioned at a predetermined position in the die 7, and the second intermediate product 6 is plastically deformed along the blade portion 9, thereby forming a concave portion 18 in the outer peripheral portion of the second intermediate product 6. At this time, since the second intermediate product 6 is moved downward in a positioned state in which the internal teeth 3 of the second intermediate product 6 are guided along the guide teeth 14 of the guide body 16, the concave portion 18 can be formed with high accuracy on the outer peripheral portion of the second intermediate product 6 by the blade portion 9.

Thereby, it is possible to form, as the ring gear 4 of the shank 1, the boundary portion between the recesses 18 adjoining each other in the circumferential direction on the outer periphery of the second intermediate product 6. By forming the ring gear 4 in this manner, the internal teeth 3 formed on the inner periphery and the shank 1 formed on the outer periphery can be accurately formed in the positional relationship (phase) in plan view in accordance with the positional relationship (phase) defined in design. In the punching process, the punching scrap 27 is discharged upward from the escape groove 17 provided in the outer peripheral portion of the punching punch 12. The blanking scrap 27 has a shape shown in fig. 9e, for example.

After the punching process, the punching punch 12 is moved upward, and then the sleeve 13 is moved upward by driving the release pin 25, and if the ring gear 4 is pressed upward by the sleeve 13, it can be easily removed from the die 7. The ring gear 4 manufactured by the above method is finished by performing finish cutting as shown in fig. 1e, and then by performing pin hole machining (not shown) as in the conventional art.

According to the method for manufacturing a ring gear of the present invention, since a series of forging, pressing, and punching processes are performed in addition to the finish cutting process, it is not necessary to perform a time-consuming broaching process as in the conventional art, and thus the manufacturing time can be significantly shortened and the ring gear can be manufactured with higher efficiency. Further, the utilization rate of the billet is high as compared with the conventional method which almost entirely relies on cutting, so that the cost can be greatly reduced.

Claims

1. A method for manufacturing a ring gear having a hole with internal teeth on the inner periphery and a protruding shank on the outer periphery, comprising the steps of:

a step of blanking the second intermediate product by a blanking device,

wherein the blanking device is provided with a die and a blanking punch head,

the sleeve has an outer peripheral shape identical to an inner peripheral shape of the forming groove portion, and sleeve teeth provided on an inner periphery have an identical shape to inner teeth of the second intermediate product,

the guide body has a cross section having the same shape as the hole in which the internal teeth of the second intermediate product are provided, and guide teeth capable of meshing the internal teeth with the sleeve teeth are formed on the outer peripheral portion,

moreover, the blanking process includes: