Tools – Wrench – screwdriver – or driver therefor – Rigid jaws
Patent
1997-06-12
2000-10-17
Smith, James G.
Tools
Wrench, screwdriver, or driver therefor
Rigid jaws
81186, 811211, B25B 1300
Patent
active
061314935
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a torque transmission unit comprising a male clamp member such as a bolt and a female clamp member such as a wrench, and more particularly to a torque transmission unit comprising male and female clamp members which have engaging portions thereof designed such that they can transmit a large amount of torque without greatly damaging the male and/or female clamp member.
BACKGROUND ART
In general, a male clamp member such as a bolt, a screw, etc. is fastened to a work by means of a female clamp member such as a wrench, a driver, etc. At this time, it is important to cause effective transmission of torque between the male clamp member (located radially inside) and the female clamp member (located radially outside).
To this end, the conventional torque transmission unit employs a male clamp member with a hexagonal head portion and a female clamp member with a socket portion of a similar shape to the head portion, or employs a female clamp member with a cross-shaped groove and a male clamp member with a corresponding cross-shaped projection.
In the conventional clamp method, however, application of excessive torque may well round a corner portion of the male clamp member and/or a groove portion of the female clamp member.
This is because there is a clearance for fitting between engaging surfaces of the male and female clamp members. The clearance permits slight rotation of the male clamp member in the female clamp member, resulting in, for example, concentration of a clamp force on a corner portion of the male clamp member. As a result, the corner portion will be rounded or deformed. Such rounding or deformation will interrupt effective transmission of torque.
Moreover, while the male clamp member rotates in the female clamp member, the axis of rotation of the former may well deviate from that of the latter. In such a state, torque cannot uniformly be applied to the clamp members, with the result that even a relatively small amount of torque may round a corner portion, etc. of the male clamp member, thereby interrupting effective transmission of torque.
Thus, in the conventional torque transmission unit, it is necessary to perform clamping while adjusting the amount of torque so as not to damage the clamp members.
The present invention has been developed in light of the above-described circumstances, and aims to provide a torque transmission unit capable of transmitting a large amount of torque without greatly damaging male and female clamp members incorporated therein.
DISCLOSURE OF INVENTION
According to a first aspect of the invention, to perform clamping, a female clamp member which has curved inner peripheral surfaces with an outline consisting of circular arcs circumscribing the sides of a square, respectively, is engaged with a male clamp member which has curved outer peripheral surfaces with an outline consisting of circular arcs circumscribing the sides of a square, respectively.
According to a second aspect of the invention, each curved inner peripheral surface of the female clamp member is made to have a smaller curvature than each curved outer peripheral surface of the male clamp member, such that the curved outer peripheral surfaces rotate relative to the curved inner peripheral surfaces and slide thereon.
According to a third aspect of the invention, each of the curved inner peripheral surfaces of the female clamp member and a corresponding one of the curved outer peripheral surfaces of the male clamp member are brought into contact with each other when the female clamp member is rotated in a direction through a predetermined angle relative to the male clamp member, and are brought out of contact from each other when the female clamp member is rotated in a direction opposite to the aforementioned direction.
According to a fourth aspect of the invention, the male clamp member and the female clamp member are made to have the same axis of rotation by rotating the male and female clamp members relative to each other, thereby bringing each of the curved o
REFERENCES:
patent: 4765009 (1988-08-01), Hung
patent: 4938731 (1990-07-01), Nguyen et al.
patent: 5019080 (1991-05-01), Hemer
patent: 5020954 (1991-06-01), Dreger
patent: 5279190 (1994-01-01), Goss et al.
patent: 5388486 (1995-02-01), Ruzicka et al.
Tanaka Michihiko
Yamamoto Toshiji
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