EP0066640B1

EP0066640B1 - Rapid advancing and retracting mechanism for clamping device

Info

Publication number: EP0066640B1
Application number: EP81104412A
Authority: EP
Inventors: Anny Hu
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-06-09
Filing date: 1981-06-09
Publication date: 1985-10-16
Also published as: EP0066640A1; ATE16084T1; DE3172658D1

Abstract

Advancing and retracting mechanism for clamping means comprising a pair of split nuts (3, 3 min ) resiliently retained in place inside a hollow cylindrical body (1) by spring means, which mechanism can either slidably hold a screw spindle (2) to rapidly push it to working position or retract it to dismount the workpiece when the threads (31, 31 min ) of split nuts (3, 3 min ) are not in mesh with the screw spindle (2) or offer a snug. Complete engagement between the split nuts (3, 3 min ) and screw spindle (2) in which the load is equally distributed, thereby largely reducing the wear thereof, and allowing the device to be fabricated in relatively small size.

Description

The present invention relates to a rapid operating mechanism for advancing or retracting the screw spindle of clamping means, for example clamps, vises, and such-like.
Yet known clamping devices fall into two categories: manual type, and hydraulic type. Despite its relatively high cost of production, the application of the former is much limited due to the structure thereof, and adapted only to special C-clamps. Moreover, such device entails a preparatory step to set the screw in operating position and is therefore inconvenient. For this reason, it is not preferably accepted by the public. While the cost of production of the latter is also high, it is not adapted to ordinary use. Provided with a hydraulic chamber, the layout of such device is inconveniently bulky, thus limiting its application to some specialized works.
A yet known means to obtain the rapid advance or retraction of clamping means to fasten or release the workpiece is accomplished by an eccentric nut provided with thread means on half of its internal surface, which nut, normally does not in engagement with the screw spindle, yet when turned inside a hollow cylindrical body in the frame, will produce a radial displacement such that its half-threads engage with the screw spindle penetrating through it. Rapidly as it can fasten or release the workpiece, such device suffers several disadvantages as follows:

1. Since only half of the inner wall is provided with thread, the load is mostly exerted on the threaded portion in operation, therefore largely increasing the wear of the thread and screw spindle. Moreover, such device cannot convert the torsion of the operator completely and efficiently into the pressure against the workpiece, particularly when the load is heavy.
2. The provision of a cylindrical body and the eccentric nut renders the size of the resulting assembly inconveniently large, which largely limits the use of such device. Also, the nut must provide enough number of threads to convert the angular torque into axial thrust, thus the required length is also inappropriately long.
3. In operation, only three effort points are bearing the propulsion of the screw spindle, thus causing the wear of the entrance and the exit of the cylindrical body, and enlarging the size of the opening thereof after long use, so that the screw spindle is liable to slacken during operation and fails to hold the workpiece snugly and securely.

Another known means (US-A-3,669,440), comprising also a half-nut but supported by a yoke about the screw spindle, with a spring carried by the yoke bearing against the spindle, has the same deficiencies.
Accordingly, it is the chief object of this invention to provide a rapid advancing and retracting mechanism to supersede the yet known means, thereby curing the deficiencies of the latter.
The invention concerns a rapid advancing or retracting mechanism for a clamping device, comprising a screw spindle, a nut provided with female threads which can mesh with the male threads of said screw spindle, support means for said nut and spring means, said support means and spring means cooperating with each other so that when said nut is not in mesh with said spindle, at least part of said nut is resiliently urged against the spindle, insomuch that the screw spindle is allowed to make frictional axial movement in said nut, and the nut can frictionally co-rotate with said spindle, and a radial displacement of said nut with respect to the axis of said spindle is produced when the nut co-rotates with said spindle, so that the threads of said nut and the threads of said spindle engage when said spindle is turned in a first direction of rotation that produces axial advancing of the spindle, or disengage when said spindle is turned in a second direction of rotation that produces axial retracting of the spindle, characterized in that said nut comprises a pair of nut halves which, when completely meshing with the screw spindle, form an entire nut having a cylindrical outer surface, that said support means comprises a hollow body receiving said pair of nut halves therein and provided with two opposite pins projecting inwardly from its inner wall symmetrically to the central axis thereof, that said spring means comprise two springs each of which has one of its ends fixed to one end of one of said nut halves, so that the nut halves are resiliently biased toward the spindle, and that stop means are provided for preventing said nut halves and said spring means from further co-rotation in said first direction with said spindle when said nut halves are completely in mesh with the threads of said spindle.
Owing to the pair of nut halves which constrict to knuckle the screw spindle when the latter is turned in one direction (i.e. the direction which results in advance) and expand to release the screw spindle when the latter is turned in the other direction (i.e. the direction which results in retract), the load is equally distributed to the two nut halves as well as the periphery of the screw spindle, thus largely reducing the wear thereof.
According to a preferred feature of the invention, the said two springs are interconnected in an end-to-end manner to define a loop wrapping around said nut halves and each of said two springs is provided with elongate slots extending along the length of the spring along the path that said pins make relative to the springs when each spring is turned in said hollow body, including an open slot and a close slot, separated by a stop piece which is so positioned that when the threads of said nut halves are completely in mesh with said screw spindle, the springs are stopped by said pins with their stop piece lying in the pins' path of relative motion.
Preferably, each spring is formed integrally by a piece of highly tough, resilient metal.
Additional objects of the invention will be brought out in the following description of a preferred embodiment of the same taken in conjunction with the accompanying drawings, in which:

Figure 1A is a partial sectional view of this invention in released condition;
Figure 1 B is a partial sectional view as A, in engaged condition;
Figure 2 is a graphical representation of one of the two same springs used in this invention, respectively showing the plan view, and edge view of the spring in straightened and bent states;
Figure 3A and Figure 3B are respectively the transverse sectional views showing the screw spindle and the split nuts in disengaged and engaged state;

Figure 4 is an embodiment of this invention. Referring now to Figures 1A and 1B, this invention comprises a hollow cylindrical body 1 for receiving a pair of split nuts 3, 3', resiliently retained in place by a pair of springs 4, 4'. The inner wall cylindrical body 1 is provided with two opposite pins 11 which form an integral part of cylindrical body 1. Referring to Figures 3A and 3B, the broken lines with reference numerals 31 and 31' designate the female thread of the split nuts 3, 3'. The arrow X in Figures 1A and 1 B indicates the direction of the advance of the screw spindle 2. In Figure 3A, the threads 31 and 31' of nuts 3, 3' are not in mesh with the male thread 21 of screw spindle 2, thus allowing the screw spindle to be pushed axially to the working position or retracted directly without turning. Under such conditions, the two split nuts 3, 3' are spaced apart by a gap. However, in order to retain the two split nuts 3, 3' in position, they are interconnected by two like springs 4, 4' which are connected in a head-to-tail manner to define a loop wrapping around the nuts. The outer surface of each of split nuts 3, 3' is provided with a groove 33, 33' to receive the heads 43, 43' of springs 4, 4'. Each of the tails 42, 42' of springs 4, 4' is structured to engage with the heads 43', 43 of another spring. In Figure 2, there is shown a plane view of one of the aforementioned springs, which is formed integrally by a highly tough, flexible and machine- able steel plate with two slots including a closed slot 44 and an open slot (not numeralled) extending along the length of the spring to allow a pin to pass through. A stop piece 41 divides the slot into two. Both sides of ends of the heads 43, 43' are flanged, to define an inserter 431 to insert into groove 33 and to abut the tail 42 of another spring, whereas only one side of the end of the tail 42 is flanged. Empirically, a tapering 34, 34' of the thickness of the nut wall at the two margins is found to give better results.
As shown in Figures 3A and 3B, when the screw spindle 2 is turned in a first direction, the split nuts 3, 3' together with springs 4, 4' are also turned in this direction until the stop pieces 41, 41' touch pins 11 so that the split nuts 3, 3' and the springs 4, 4' can no more be turned. Now the gaps between the two split nuts 3, 3' diminish. A resulting nut fully in mesh with screw spindle 2 is formed. Inasmuch as the nut can no more be turned, the screw spindle 2 can now be turned in the first direction relative to the nut to produce an axial thrust.
To bring the state in Figure 3B back to that of Figure 3A, one only needs to make about half a turn of the screw spindle 2 in a second or reverse direction. The operation of this invention is similar to the prior art, but the result is much better. Figure 4 is an embodiment of this invention. In operation, one only needs to push the screw spindle 2 forward to touch the workpiece, and then fasten it with a few turns in the first direction. Likewise, while dismounting the workpiece, one only needs to make a turn in reverse direction, then pull the screw spindle 2 back.

Claims

1. A rapid advancing or retracting mechanism for a clamping device, comprising a screw spindle (2), a nut (3, 3') provided with female threads (31, 31') which can mesh with the male threads (21) of said screw spindle (2), support means (1) for said nut (3, 3') and spring means (4, 4'), said support means (1) and spring means (4, 4') cooperating with each other so that when said nut (3, 3') is not in mesh with said spindle (2), at least part of said nut (3, 3') is resiliently urged against the spindle, in order that the screw spindle is allowed to make frictional axial movement in said nut, and the nut can frictionally co-rotate with said spindle, and a radial displacement of said nut with respect to the axis of said spindle is produced when the nut co-rotates with said spindle, so that the threads of said nut and the threads of said spindle engage when said spindle is turned in a first direction of rotation that produces axial advancing of the spindle, or disengage when said spindle is turned in a second direction of rotation that produces axial retracting of the spindle, characterized in that said nut comprises a pair of nut halves (3, 3') which, when completely meshing with the screw spindle (2), form an entire nut having a cylindrical outer surface, that said support means comprises a hollow body (1) receiving said pair of nut halves (3, 3') therein and provided with two opposite pins (11) projecting inwardly from its inner wall symmetrically to the central axis thereof, that said spring means comprise two springs (4,4') each of which has one of its ends fixed to one end of one of said nut halves (3,3'), so that the nut halves (3, 3') are resiliently biased toward the spindle, and that stop means (41, 41') are provided for preventing said nut halves (3, 3') and said spring means (4, 4') from further co-rotation in said first direction with said spindle when said nut halves are completely in mesh with the threads (21) of said spindle (2).

2. The mechanism according to claim 1, wherein the said two springs (4, 4') are interconnected in an end-to-end manner to define a loop wrapping around said nut halves (3, 3') and wherein each of said two springs (4, 4') is provided with elongate slots extending along the length of the spring (4, 4') along the path that said pins (11) make relative to the springs (4, 4') when each spring is turned in said hollow body (1), including an open slot and a closed slot (44), separated by a stop piece (41) of the stop means which is so positioned that when the threads (31, 31') of said nut halves (3,3') are completely in mesh with said screw spindle (2), the springs (4, 4') are stopped by said pins (11) with their stop piece (41) lying in the pins' path of relative motion.

3. The mechanism according to claim 2, wherein each spring (4, 4') is formed integrally by a piece of highly tough, resilient metal.