Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Thread or shank structure
Patent
1981-04-09
1984-10-30
Holko, Thomas J.
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Thread or shank structure
411421, 411437, F16B 3302, F16B 3708
Patent
active
044797486
DESCRIPTION:
BRIEF SUMMARY
The subject invention relates to screws and screw joints of the kind comprising a screw spindle body formed with at least one non-threaded section extending along the spindle body, and at least one nut member formed with a threaded section which matches the non-threaded section on the screw spindle body. The screw spindle body and the nut member are arranged to move axially relative to one another, during which movements the threaded nut member section travels along the non-threaded section of the screw spindle body. The screw spindle and the nut member may also be turned relative to one another to effect engagement between said nut member section and the threads of the screw spindle body.
Screw spindles and screw joints of this type permit rapid displacement of the screw spindle body and nut member axially relative to one another, thus giving a quick grip and a quick release action, and screw spindles and screw joints of this kind may be used for instance in vices or valves adapted to shut off large flows quickly.
One problem inherent in screw joints of this kind is that removal of the threads on one or several sections of the screw body and the nut member results in a considerable reduction of the strength of the screw joint. The screw spindle threads, being the weakest ones, are those most exposed to stress. Another problem is the difficulty in obtaining, in a resonable manner, an advantageous distribution of the area of thread engagement over the periphery of the screw spindle body. The most common solution to this latter problem is to divide the threaded portion into two, three or four sections which are distributed symmetrically over the periphery. However, this arrangement adds considerably to the manufacturing costs and in addition weakens the threads further, since each screw thread in each section requires two bevelled entrances. Furthermore, additional portions of the faces of engagement of the threads cannot either be used because of the clearance that is required between the threaded sections of the screw spindle body and the nut member. Such clearance is necessary, as any dirt or dust particles that might enter between the screw spindle body and the nut member could otherwise easily interfere with the operation of the screw or screw joint. An additional disadvantage with the provision of several threaded sections is that it increases the number of angular positions in which the threads are completely out of mesh, and the consequence is a reduction of the circumferential length over which grip is possible.
The purpose of the invention is to eliminate the disadvantages outlined above in screws and screw joints of the kind referred to. The subject invention provides a screw joint possessing considerably enhanced gripping strength compared with prior-art screw joints of this type.
In accordance with the teachings of the invention, this is achieved in that the non-threaded section of the screw spindle body as well as the threaded section on the nut member extend helically along the screw spindle body and the nut member, respectively.
The invention will be described in closer detail in the following with reference to some embodiments thereof illustrated in the accompanying drawings, wherein
FIG. 1 is a lateral view of a screw joint in accordance with the invention, showing a first embodiment thereof,
FIG. 2 is a lateral view of the screw joint in accordance with a second embodiment, and
FIGS. 3 and 4 are sectional views of nut members cooperating with the screw joints shown respectively in FIG. 1 and in FIG. 2.
The screw joint of FIG. 1 consists of a screw spindle body 1 and a nut member 2 and they are illustrated in their tightened positions on either side of a work piece 3. In accordance with the invention, the screw spindle body is formed with a threaded portion 4 extending around the screw spindle along the entire length thereof, as well as with a section 5 which is not threaded and which extends helically around the screw spindle body, separating the threads thereon. The section 5 forms a heli
REFERENCES:
patent: 476316 (1892-06-01), Rodgers
patent: 506485 (1893-10-01), Fichner
patent: 1296038 (1919-03-01), Baker
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