Plastic article or earthenware shaping or treating: apparatus – Preform reshaping or resizing means: or vulcanizing means... – By fluid pressure actuated flexible diaphragm
Patent
1996-07-12
1998-04-28
Nguyen, Khanh P.
Plastic article or earthenware shaping or treating: apparatus
Preform reshaping or resizing means: or vulcanizing means...
By fluid pressure actuated flexible diaphragm
425389, 425392, 72478, 72352, 72360, B21D 5316
Patent
active
057441758
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a device for expanding rotationally symmetrical shaped parts, particularly bearing cages, comprising a divided expanding mold, a pressure die and a pressurizing means.
STATE OF THE ART
An already known device of this type comprises a two-part expanding mold whose mold halves are pressed firmly against each other during the shaping process by a conical ring. A rubber ring used as a pressurizing means is pressed radially outwards by a longitudinally displaceable die so that the inserted sheet metal blank to be shaped is pressed by the rubber ring into the desired final shape. The two mold halves are then separated and the finished shaped part can be removed (Oehler, Kaiser: Schnitt-, Stanz- und Ziehwerkzeuge, Springer Verlag, Berlin, Heidelberg, New York 1973, Page 502).
The drawback of such a device is the two-piece configuration of its expanding mold. A misalignment of the two mold halves at the mold joint can lead to material accumulations in the part shaped therein and have a detrimental effect on its later operation. For example, in the case of bearing cages, this material accumulation could be in the form of a sharp-edged flash on the end faces and cause damage when the cage contacts the rims of a bearing ring. It is therefore necessary to remove such accumulations of material in an additional work step such as grinding so that the products in which such a shaped part is used become more expensive.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to configure an expanding mold for bearing cages such that no accumulations of material occur at points of frictional contact.
SUMMARY OF THE INVENTION
The invention achieves this object by the fact that, measured with reference to an already expanded shaped part, a mold cavity of the expanding mold extends in axial directions at least as far as the regions of the end faces of the shaped part and is delimited axially by a continuous annular mold at each end while being defined in radial direction in the region of the peripheral surface of the shaped part by two mold halves.
This four-part configuration of the expanding mold assures that the mold cavity is uninterrupted in the functionally important contact regions of the shaped part, i.e. at the end faces of the rolling bearing cage so that there are no mold parting lines and therefore no undesired accumulation of material in these regions. Due to the two-part configuration of the expanding mold in the region of the peripheral surface of the rolling bearing cage, material accumulations occur only in this region where, however, they present no problem because in cages guided by rolling elements there is no contact between the outer raceway and the regions of material accumulations.
If the shaped part to be expanded presents different diameters at its peripheral surface, as is the case for example with M-shaped cages, according to an advantageous embodiment of the invention, the mold parting plane between the annular molds and the mold halves is arranged in the region of the smallest diameter of the peripheral surface of the shaped part. By this measure, any material accumulations are shifted towards the center of the rolling bearing cage and have no contact with the raceways even in the case of raceway-guided cages.
In a further development of the invention, the parting plane between the continuous annular molds and the mold halves extends vertically or inclined to the central axis of the expanding mold. In the first case, the manufacture of the four-part mold is facilitated while in the second case, the inclined configuration simplifies the assembly of the four parts into a whole.
The invention will now be described more closely with the help of some examples of embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial longitudinal cross-section of a four-part expanding mold of the invention;
FIG. 2a is a cross-section taken along line IIa--IIa of FIG. 1;
FIG. 2b is a cross-section taken along line IIb--IIb of FIG. 1;
FIG. 3
REFERENCES:
patent: 2088265 (1937-07-01), Hulin et al.
patent: 2305803 (1942-12-01), Bayer
patent: 2689539 (1954-09-01), Lyon
patent: 3732836 (1973-05-01), Molloy et al.
patent: 3983739 (1976-10-01), Randolph
patent: 4723430 (1988-02-01), Hahn
patent: 4984445 (1991-01-01), Ohuchi et al.
Lingner Horst
Muntnich Leo
Steinberger Wolfgang
INA Walzlager Schaeffler KG
Nguyen Khanh P.
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