GB2035869A - Screwing up or thread chasing machine - Google Patents

Abstract

An apparatus for loosening and displacing nuts which are stuck fast on screws of considerable lengths has a nut retaining chuck 16 which has a through bore to receive the screw and is rotatable by gears and chains. The screw is held against rotation by a two-jaw clamp 37, 38 which is free to move relative to the chuck 16, on rollers 28. Rotation of the chuck causes the nut to be displaced along the screw. Limit switches 42, 43 can be provided to effect a predetermined displacement of the nut along the screw. The apparatus can chase out existing screw-threads. The chuck may be freely movable relative to the clamp. <IMAGE>

Description

SPECIFICATION Apparatus for releasing screw threaded members The present invention concerns an apparatus for releasing and effecting relative displacement between two inter-engaged screw threaded members.

The invention is particularly suited for loosening nuts and the like which are stuck fast on screw threaded members and for displacing nuts and the like between required positions on screw threaded members. The invention provides an apparatus which can receive screw threaded members of considerable lengths, for example scaffolding and screw-jacks as used in ship-building, and irrespective of the positions along said members of the nuts to be displaced.

According to the present invention an apparatus for effecting relative displacement between inter-engaged male and female screw threaded members comprises a power driven chuck assembly having a chuck head to receive the female member, an axial bore through the chuck assembly to allow passage of the male member, an assembly for clamping the male member against rotation, and freely movable support means for one of said assemblies whereby with the female member located in the chuck head and the male member secured in the clamping assembly rotation of the chuck head causes the displacement of the female member along the male member.

The invention will be described further, by way of example, with reference to the acompanying drawings; in which: Figure 1 is a schematic plan view of an embodiment of an apparatus according to the invention; Figure 2 is a schematic elevation of the apparatus of Fig. 1; Figure 3 is a selection on the line A-A in Fig. 1; Figure 4 is an end view of a head chuck forming a part of the apparatus; and Figure 5 is a section on the line B-B in Fig.

1.

The apparatus comprises a base 1, conveniently formed from channel-shaped sections, mounted on legs 2. A chuck assembly and associated drive mechanism is mounted on one end of the base 1, the left hand end as shown in the drawings. A clamping assembly carrying jaw blocks is supported between side frame members 3 of the base, the clamping assembly being freely movable along the base 1.

The chuck assembly and associated drive mechanism is mounted on a support platform 4. A drive motor 5 is coupled through a gear box 6 to chuck assembly 7. Thus, drive shaft 8 of motor 5 is provided with pinion 9 which is linked by chain 10 to chain wheel 11 of the gear box 6. In turn, the output shaft 12 of the gearbox 6 is provided with chain pinion 1 3 which is coupled by chain 1 4 to chain wheel 1 5 on the chuck assembly. Purely by way of example, the pinion 9 can have 1 9 teeth at a chain pitch of 0.5 inch Duplex and the wheel 11 can have 57 teeth at the same pitch.The pinion 1 3 can have 1 4 teeth at a pitch of 54 inch Duplex and wheel 1 5 can have 56 teeth also at a pitch of 54 inch Duplex. It will be appreciated that the above sizes are given merely as examples and that the drive mechanism is not confined to chain wheels and pinions. Likewise, although each pinion and wheel is shown as a double or twin assembly with two chains between each cooperating pinion and wheel it will be appreciated that the drive mechanism is not restricted to such an arrangement.

With reference to Fig. 3, the chuck assembly comprises a head 1 6 which is bolted or otherwise secured to flanged end of a tubular head shaft 1 7. The chain wheel 1 5 is splined or keyed to the shaft 17 by key 18. The shaft 1 7 is journalled for rotation in a head block 19, suitable bearings 20 being provided about the shaft. A collar 21 is secured to the end of the shaft projecting beyond the end of the block 1 9. Thrust washers 22 are arranged between the collar 21 and the adjacent end of the block 1 9 and also between the opposite end of the block and the wheel 1 5. A spacer 23 is provided between the wheel 1 5 and the flanged end of the shaft 1 7.

The head 1 6 is formed with an opening 24 to receive and engage a nut.

In Fig. 4, the opening 24 is hexagonal although again this is purely an example. A locking plate 25 is mounted by means of a locking pin 26 in a recess in the free end face of the head 1 6. The locking plate 25 has a cut-out portion which conforms to the shape of the opening 24. Thus, in Fig. 4 the locking plate is shown in a position to enable free unimpeded access to the opening 24, the cutout portion being a notch having an angle equal to the included angle of 120 between two sides of the hexagonal opening 24. The plate 25 can be rotated about the axis of the pin 26 to a position to obstruct the opening and as shown in Fig. 3.

The clamping assembly comprises a saddle 27 located between side frame members 3.

The saddle 27 is provided with wheels which engage and run along a flange of each side frame member 3. With reference to Figs. 1 and 5, four flanged saddle wheels 28, arranged two at each end of the saddle, run on the upper surfaces of the side frame members 3. Two further saddle wheels 29 (Fig. 5) located on the longitudinal centre line of the saddle and are at each end of the saddle bear against the lower surfaces of the flanges of the side members 3. The wheels 29 are preferably bevelled or chamfered to match a corresponding taper on the flange.

With reference to Fig. 5, a left hand/right hand screw 30 is journalled in blocks 31 carried on the saddle. The screw 30 is located in position by locking collars 32 which are secured to the screw shaft to abut against the blocks 31. Between the blocks 31 the screw 30 is provided with two opposite screw threads 33 and 34 which are separated by an unthreaded central portion 35. For example, the thread 33 at the left in Fig. 5 can be a left hand screw thread and the thread 34 at the right in Fig. 5 can be a right hand screw thread. Thrusf washers 36 are provided between the blocks 31 and the screw thread portions 33 and 34.

A jaw block 37, having an appropriately threaded bore, is mounted on each of the screw threads 33 and 34. Each block 37 carried a removable jaw 38. The blocks are slidable on supports 39 arranged beneath the saddle. Conveniently, two supports 39 are provided and are arranged one along each side of the saddle. Each support can be substantially L-shaped in section with base portions 40 directed inwardly towards each other and serving as slides for the jaw blocks.

The jaw blocks 37 are disposed equidistantly one at each side of a centre line which coincides with the axis of the chuck head.

The screw 30 extends outwardly beyond one of the side frame members 3 and terminates in a hand wheel 41 or the like. Preferably the hand wheel is mounted on an extension shaft which is releasably connected to the end of the screw 30.

The apparatus operates as follows:- Suppose it is required to release a nut fast on a long screw threaded member, for example a length of scaffolding. The screw threaded member is positioned along the axis of the apparatus with the nut located in the chuck head and the member itself clamped between the jaws 38. The jaws 38 are brought into firm clamping engagement with the member by means of the handwheel 41, rotation of which actuates simultaneous movement of the jaw blocks 37. The chuck assembly has a through bore formed by the openended tubular head shaft 1 7. Consequently, the portion of the screw threaded member extending beyond the nut remote from the clamping assembly can be passed into and through the bore.The chuck assembly can therefore receive a nut which can be located at any distance from an end of the screw threaded member.

With the nut located within the chuck head 16, the locking plate 25 is actuated to a position to prevent axial withdrawal of the nut. The drive mechanism is actuated to rotate the chuck head 1 7 and hence the nut located therein. As the screw-threaded member carrying the nut is held between the jaws 38 the nut winds or unwinds itself along the screw thread, this being possible as the sad dle is free to run along the frame members 3.

If desired, the nut can be displaced to a predetermined position along the screw threaded member. This can be achieved by controlling the extent of movement of the saddle. Thus limit switches or the like can be adjustably positioned along the path of travel of the saddle to control the operation of the drive mechanism for the chuck head. Two such limit switches are denoted diagrammatically in Fig. 1 by the reference numerals 42 and 43. If; for example, the saddle is drawn to the left upon rotation of the nut in the chuck head then the switch 42 can be located at a position spaced from the initial position of the saddle by a distance equal to that to be moved by the nut along the screw thread. The drive mechanism is stopped when the saddle contacts the switch 42.

The apparatus can also be used for chasing out an existing thread on a screw threaded member.

It will be appreciated that a variety of different chuck heads can be fitted to the chuck assembly. The chuck head is releasably mounted on the flanged end of the shaft 1 7 whereby it can readily be changed as and when required during operation of the apparatus. Thus the apparatus can be used to receive different types and sizes of nuts and the like female members.

It will be further appreciated that alternatively, the chuck assembly can be mounted for linear movement along the frame members with the clamping assembly fixed at a set position.

Claims (6)

1. An apparatus for effecting relative displacement between interengaged male and female screw-threaded members comprising a power driven chuck assembly having a chuck head to receive the female member, an axial bore through the chuck assembly to allow passage of the male member, an assembly for clamping the male member against rotation, freely movable support means for one of the chuck assembly and the clamping assembly whereby with the female member located in the chuck head and the male member secured in the clamping assembly rotation of the chuck head causes the displacement of the female member along the male member.

2. An apparatus according to claim 1 in which the chuck assembly is stationary and the clamping assembly is movable towards and away from the chuck assembly.

3. An apparatus according to claim 2 including a support frame for the clamping assembly, the clamping assembly comprising a saddle arranged to travel along the frame and a pair of jaw blocks disposed on the saddle one at each side of the axis of the chuck assembly.

4. An apparatus according to claim 3 including means for effecting simultaneous and equal displacements of the jaw blocks, to engage and disengage the male member.

5. An apparatus according to claim 1 including means for effecting a predetermined displacement of the female member along the male member, said means comprising limit switches positioned in the path of movement of the saddle to isolate the drive to the chuck assembly on contact by the saddle.

6. An apparatus for effecting relative displacement between interengaged male and female screw-threaded members substantially as herein described with reference to and as illustrated in the accompanying drawings.