Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Internally threaded fastener element – e.g. – nut – etc. – Multipart
Reexamination Certificate
1998-11-27
2001-07-17
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Internally threaded fastener element, e.g., nut, etc.
Multipart
C411S428000, C411S917000
Reexamination Certificate
active
06261041
ABSTRACT:
DETAILED DESCRIPTION
1. Technical Field of the Invention
This invention is a clamping screw such as an attachment nut or an attachment bolt and used to fix to the drive shaft of an electric tool a rotating tool such as the grindstone of a hand grinder or a circular hand saw, and relates to a clamping screw which is able to clamp by increasing the torque of a manually input rotational force.
2. Prior Art
The above-mentioned attachment nuts or bolts in prior art are clamping screws comprised of a threaded member forming a thread for attachment to the drive shaft of said electric tool, an operating ring to which the rotational force for clamping is input manually, and a differential retardation mechanism provided between these which increases torque by retarding the rotational force of the operating ring (for example, Japanese Patent No.4-257419).
Since the above-described differential retardation mechanism increases the torque by retardation, despite the advantage that the rotating tool can be clamped and fixed strongly with a small rotation of the operating ring, the mechanism is complex and has the disadvantage that precision is required in manufacture.
Problems To Be Resolved By The Invention
This invention has as its purpose the provision of a clamping screw which, unlike a structure such as the above-mentioned differential retardation mechanism, is not complex and does not require precision manufacture, has a power structure (a torque-increasing mechanism) of simple construction, and is able to clamp powerfully with a small rotational input.
This invention is characterized in being a clamping screw provided with a threaded member forming an attachment thread which screws together with the thread for attachment of the member to be attached to the shaft part, an operating ring supported on the outer surface of the outer end of said threaded member so as to freely rotate only and to which rotational force is input, a flange ring inserted over the outer surface of the inner end of said threaded member and having a flange surface which abuts the object to be attached on the clamping side from the inner end of said threaded member, and a torque-increasing mechanism on the outer surface of said threaded member between said operating ring and said flange ring and which increases the torque of the rotational force of the operating ring transmitting this to the flange ring, said torque-increasing mechanism being comprised with an inclined cam surface which applies an effective force in the direction of clamping to elements in contact through the rotation in the direction of clamping of said operating ring formed in the circumferential direction of the inner surface of said operating ring, a cam ring which is freely slidable in the axial direction only inserted over the outer surface of said threaded member, a coupled inclined cam surface which corresponds to the sloping cam surface of said operating ring formed on said cam ring, a needle bearing supported on a retainer fitted between the inclined cam surface of said operating ring and the coupled inclined cam surface of said cam ring, and a spring fitted between said cam ring and said operating ring which returns said cam ring to its initial position when the cam ring is not in operation, and moreover is characterized in being a clamping screw fitted with an adjustment ring between said cam ring and flange ring which applies to an adjustment to the rotation relative to the operating ring.
According to the invention, up until the point where the flange surface of the flange ring abuts the object to be attached with the attachment thread of the threaded member screwed onto the thread for attachment of member to be attached, since the screw resistance of the attachment thread of the threaded member is small, when the operating ring is rotated the threaded member rotates integrally due to the load resistance of the torque-increasing mechanism, the attachment thread of the threaded member being screwed onto the attachment thread of the member to be attached. When the flange surface of the flange ring comes in contact with the object to be attached, the forward screwing motion of the threaded member ceases and the rotational force on the operating ring thereafter acts on the torque-increasing mechanism and the inclined cam surface on the operating ring side of said mechanism presses against the coupled inclined cam surface of the cam ring via the needle bearing, so that said cam ring presses against the flange ring on the side in the direction of clamping through the increased torque force applied by the cam, the object to be attached being clamped by this increased torque pressure.
As a result of the above, since the torque-increasing mechanism is comprised of an inclined cam surface and a coupled inclined cam surface, the structure of the torque-increasing mechanism is simplified, manufacture is simple, and a satisfactory improvement in torque can be obtained without the requirement for precision.
Moreover, the use of a needle bearing results in linear contact with the inclined cam surface, so that smooth operation can be achieved over long periods without damage in the form of dents which interfere with smooth rotation being caused by extremely heavy loads acting to the cam surface through point pressure from, for example, ball-bearings.
Furthermore, by fitting an adjustment ring, it is possible to sense the degree of increased torque clamping. Moreover, it is possible to prevent both inclined cam surfaces overriding one another by means of two return springs or one return spring and position-restricting balls and restricting grooves, so that an accurate clamping and releasing action can be obtained.
REFERENCES:
patent: 4955744 (1990-09-01), Barth et al.
patent: 5388942 (1995-02-01), Bonacina et al.
patent: 5567100 (1996-10-01), Nakamura
patent: 5810533 (1998-09-01), Nakamura
patent: 5871322 (1999-02-01), Nakamura
patent: 5899648 (1999-05-01), Kanaan et al.
patent: 6050741 (2000-04-01), Aultman et al.
Nelson Mullins Riley & Scarborough
Wilson Neill
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