Rotary shafts – gudgeons – housings – and flexible couplings for ro – Coupling accommodates drive between members having... – Coupling transmits torque via radially spaced ball
Reexamination Certificate
2000-05-25
2002-06-18
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Coupling accommodates drive between members having...
Coupling transmits torque via radially spaced ball
C403S359100, C072S060000, C464S111000, C464S905000, C464S906000
Reexamination Certificate
active
06406374
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a molding method for components having grooves and the like in its inner diameter and a molding device for the same. More specifically, the relevant components are preferably tubular components, such as constant velocity joint outer rings and internal gears and the like for automobiles. The grooves and the like refer to grooves which guide rolling elements and irregularities of gears. Constant velocity joints include tripod type, ball joint type, Rzeppa type, and the like. Internal gears include helicals. The present invention also relates to an outer ring for a constant velocity universal joint used in drive systems and the like of automobiles. The present invention further relates to a method of joining a tubular component and a shaft component useful in, for example, universal joints of automobile drive systems.
Conventional outer rings for constant velocity joints include a tubular component and a shaft component press molded in a unitary manner by a multi-step cold forging process. This multi-step process includes annealing and surface lubrication treatment of a cylindrical material, forward extrusion, swaging, annealing and surface lubrication treatment, rear extrusion, annealing and surface lubrication treatment, and, in the inner perimeter of the tubular component, molding of a catching part to engage with a bearing.
In recent years, in order to lighten the outer ring of the constant velocity joint, a method has been introduced wherein the outer ring of the constant velocity joint is separated into a tubular component and a shaft component. After press working to form these components, they are coupled and made unitary. The present inventors have studied methods for coupling the tubular component and shaft component of such outer rings of a constant velocity joint.
Japanese Laid-Open Publication No. 7-317792 discloses an outer ring of a constant velocity joint and its manufacturing method. A pipe is used and molded into a shell type outer ring. This conventional outer ring has a tubular component, a joint part, and a cylindrical part. A serration groove is formed on the cylindrical part, or, in the alternative, the cylindrical part is formed as a polygon. One end of the cylindrical part is coupled with the shaft. In another embodiment, a joining member is disposed between the cylindrical part and the shaft.
However, with respect to the coupling between the shell type outer ring, which is formed from pipe material, and the shaft, the coupling strength is determined by the thickness of the pipe material. Therefore, a uniform coupling force is unachievable with such a construction. Furthermore, with respect to outer rings in which a joining member is pushed into the cylindrical part, extra costs are needed to manufacture joining members having a plurality of grooves of flat surfaces in the shaft direction of the inner and outer perimeter surfaces. Extra costs and labor are also incurred from the process required for pushing the joining member into the cylindrical part. Additionally, because the constant velocity joint is constructed by the coupling of three components, specifically the outer ring, joining member, and shaft, the coupling precision of the joint part of the outer ring and shaft is a source of additional concern.
Japanese Laid Open Patent Publication No. 8-49727 discloses a constant velocity joint construction wherein a hole is provided on a shell type outer ring (tubular component). The tubular component is formed by press molding of a plate material. A plurality of grooves or flat surfaces are formed in the shaft direction of the inner perimeter surface of this hold. After a protruding part of the shaft is pushed in and engaged with the tubular component, the end surface of the protruding part is swaged. As a result, the shell type outer ring and the shaft are joined in a unitary manner.
However, with this conventional coupling method, the coupling force generated where the outer ring and the shaft are pushed in and engaged is reduced by the swaging of the end surface of the protruding part. Furthermore, because only the thickness of the outer ring is the part which engages with the shaft, a large coupling force is not anticipated. When pushing in the shaft into the outer ring, the part which engages is only the thickness of the plate of the outer ring. As a result, the engaging length is short, and there is concern that the outer ring could become deformed. The coupling precision of the tubular component and the shaft component is also a concern.
Conventional tubular components are manufactured by heat forging, cold forging, cutting, or by a method which combines two or more of these methods.
U.S. Pat. No. 2,523,372 shows an example of a technology in which a constant velocity outer ring is manufactured by heat forging and cold forging. In this patent publication, in the section entitled “Problems to be solved by the invention”, it is stated that “when molding a cup-shaped component such as a constant velocity joint outer ring, so-called rear extrusion is conducted using a punch that is the same shape as the cup inner surface shape. However, stress concentrates on one part of the punch, and cracks can occur easily, and the generation of these cracks is very sensitive to the size of the molding load. The lifespan of the mold can be greatly influenced by small differences in the stress value.”
According to the above conventional processing method, an excessive stress is applied on the die, and the lifespan of the die is short. In order to reduce the friction between the die and the material, bond treatment of the material is generally conducted. This bond treatment is disfavored due to environmental problems. In order to have a lighter weight, it is preferable to eliminate any excess from each part of the product. As a result, the outer shape is made to take on a modified shape to match the inner shape of the product. However, this cannot be realized due to the stress that is applied to the die. In other words, there is a large equipment cost, as well as a problem with precision.
Japanese Laid-Open Patent Publication No. 8-49727 discloses an example of a technology for manufacturing a constant velocity joint by a method of sheet metal molding of a constant velocity joint outer ring. This outer ring is then coupled with a shaft that is separately molded. When the constant velocity joint outer ring is molded from a sheet metal, stress on each part differs, and the product precision deteriorates. The molding of the desired detailed parts is difficult. There are a large number of steps, and the cost becomes high.
The above described conventional internal gear is manufactured by broaching the gear part and welding with a flange part which has been separately molded. It is not mass produced by cold forging. Broaching generates cutting shavings. As a result, such a method is unable to be deemed energy conserving.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a molding method and device for forming a tubular component which overcomes the foregoing problems.
It is another objection of the present invention to provide a molding method and device for forming a tubular component which has high precision, has a long die lifespan, does not require bond treatment, and is energy conserving.
It is a further object of the present invention to provide an outer ring for a constant velocity joint and a manufacturing method for the same which overcomes the foregoing problems.
It is still a further object of the present invention to provide an outer ring for a constant velocity joint and a manufacturing method for the same which, in order to lighten the overall weight, is composed by coupling a tubular component and a shaft component which are molded by press working.
It is another object of the present invention to provide an outer ring for a constant velocity joint and a manufacturing method for the same which has a strong coupling force and a high coupling precision.
Briefly
Ishinaga Nobuyuki
Kanamaru Hisanobu
Kobayashi Kazuto
Matsumura Akira
Aida Engineering Co., Ltd.
Browne Lynne H.
Dunwoody Aaron M
Morrison Law Firm
LandOfFree
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