GB2126146A - A power tool for inserting and extracting a clamp - Google Patents

Abstract

The tool has a housing (26, 27) which receives a clamp (10) at its front end. A fixed socket (30) is engageable with the body (17) of the clamp to prevent its rotation relative to the housing. A rotatable socket (32) driven by an air motor (28) via an adjustable ratchet clutch (29) is engageable with the nut (19) of the clamp and has an external screwthread (34). A sleeve (35) is axially slidably mounted on the housing and has a trigger (37) pivoted thereon. The trigger has a part thread (39) engageable with the external screw thread (34) when the trigger is depressed. Locking means in the form of balls (43) in apertures (42) are provided at the front end of the housing. To insert a clamp into a hole in a component, the clamp is put into the tool and the collet legs (12, 13) of the clamp are pushed through the hole. The motor is then rotated forwards to screw down the nut (19). A separator (16) opens the collet legs and the component is clamped between the heads (14) of the collet legs and the body of the clamp. To extract the clamp the trigger is depressed and the motor is rotated in reverse. The nut (19) is unscrewed and at the same time the sleeve (35) is moved forwards to engage the locking means to hold the clamp in the socket (30) and to push against the component so as to pull the clamp out of the hole. <IMAGE>

Description

SPECIFICATION A power tool for inserting and extracting a clamp This invention relates to a power tool for inserting and extracting a clamp of the type which comprises an externally threaded stem having at one end collet legs with heads at their free ends, a nut engageable with the threaded stem, and an axially slidable body mounted on the stem between the nut and the heads of the collet legs and carrying a separator interposed between the collet legs (referred to hereinafter as the type hereinbefore defined).

Clamps of the aforesaid type are well known and have particular application in clamping together two metal skins while an adhesive interposed between the skins is allowed to set.

Initially, the nut is unscrewed, i.e. screwed back to the end of the stem remote from the collet legs and the clamp is released by moving the body back towards the nut; in this position the separator is retracted and the heads of the collet legs are not separated. The clamp can be inserted by pushing the collet legs through aligned holes in the two skins, whereupon the nut is screwed down to move the body towards the ends of the collet legs. The separator extends forwards and opens up the legs and the two skins are clamped together between the heads of the collet legs and the body. To extract the clamp the nut is unscrewed, the body is then moved back retracting the separator and the collet legs are pulled out of the holes in the skins.

One problem is that the adhesive between the two skins seeps into the holes and this makes it difficult to remove the collet legs from the holes in the skin.

It is an object of the invention to provide a power tool for inserting and extracting clamps of the type hereinbefore defined.

According to the present invention, there is provided a power tool for inserting and extracting a clamp of the type hereinbefore defined, the tool comprising a housing having a front end for receiving the clamp and a rear end, a fixed socket at the front end of the housing engageable with the body of the clamp to prevent rotation of the clamp body relative to the housing, a rotatable socket mounted in the housing and engageable with the nut of the clamp, the rotatable socket having an external screwthread, a reversible motor for rotating the rotatable socket, the motor being rotatable in one direction to insert the clamp and in the opposite direction to extract the clamp, a sleeve axially slidably mounted on the housing, a clamp extraction operating member having a part thread thereon and mounted on the sleeve for movement between a first inoperative position and a second position in which the part thread engages the external thread on the rotatable socket such that the sleeve is moved forwards when the motor is rotating in said opposite direction, and locking means operable by forwards movement of the sleeve to hold the clamp in the fixed socket.

To insert the clamp, the clamp is put into the front of the tool and the collet legs are pushed through a hole in a component to be clamped. The motor is then rotated in said one direction to screw down the nut. To extract the clamp, the tool is slid over the clamp. Then the clamp extraction operating member is moved to its second position and the motor is rotated in said opposite direction.

The nut is unscrewed and at the same time the sleeve is moved forwards to engage the locking means so as to hold the clamp in the fixed socket and to push against the component so that the clamp is pulled out of the hole.

Preferably, a ratchet clutch is provided between the motor and the rotatable socket and is arranged to slip at a predetermined torque when the motor is rotating in said one direction but not to slip when the motor is rotating in said opposite direction.

Hence, when inserting the clamp the nut can be screwed down to a predetermined tightness.

Conveniently, the locking means comprises one or more apertures in the fixed socket, a locking element in the or each aperture and one or more internal grooves in the sleeve and aligned with the aperture or apertures in the fixed socket when the sleeve is in a rearmost position to allow the locking element(s) to move radially outwards, the arrangement being such that forwards movement of the sleeve takes the groove or grooves out 3f alignment with the aperture or apertures and the locking element(s) is/are constrained by the sleeve to move axially inwards. In this case, preferably, there are six locking elements in the form of balls which are, in use, longitudinally aligned with and disposed forwards of the corners of a hexagonal portion of the body part of the clamp.

The clamp extraction operating member may be manually operable, in which case it is preferably urged away from its second position by a spring. Alternatively, it can be operated by fluid pressure operated means in which case the sleeve can be provided with an associated return spring.

Advantageously, the pitch of the thread on the rotatable socket is arranged to be finer than the pitch of the thread on the clamp. This will ensure that the clamp is fully released before it is extracted.

Conveniently, the motor is an air motor.

Preferably, the sleeve has a plastics end piece at its front end to prevent damage from occurring to the surface of the component when the skin clamp is extracted.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 is a longitudinal sectional view through a typical clamp to be inserted and extracted by a tool according to the invention; Figure 2 is a view partly in section of one embodiment of a power tool according to the invention, in one state of operation; and Figure 3 is a view of part of the tool of Figure 2 in a different state of operation.

Referring firstly to Figure 1 , the clamp 10 shown therein comprises an externally threaded stem 11 having at one end two collet legs 12, 13 each with a part conical head 1 4 at its free end.

An axially slidable body 1 5 is mounted on the stem. The body 1 5 carries a separator 1 6 interposed between the collet legs and has a hexagonal portion 1 7 and a cylindrical portion 1 8.

The latter has a diameter equal to the spacing between each pair of opposite sides of the hexagonal portion 1 6. A hexagonal nut 1 9 is engageable with the threaded stem and a washer 20 and stiff compression spring 22 are mounted on the stem between the body and the nut. The end portion 23 of the stem remote from the collet legs has been turned down, and therefore, has no thread; this end portion is fitted with an end cap 24. The nut is retained on the stem by the end cap, and is free to turn in a counter thread engaging direction.

Referring now to Figures 2 and 3, the power tool shown therein comprises a pistol grip 25 and a generally tubular two part housing 26, 27. The rear part 26 of the housing accommodates a reversible air motor 28 and a ratchet clutch 29 and the front part 27 of the housing, which is screwed to the rear part 26, has an elongate fixed hexagonal socket 30 at its front end. The ratchet clutch 29 is of the type that can be adjusted to give the required torque when inserting a clamp, but is automatically locked against slipping when the motor operates in reverse, to extract the clamp.

A clutch spindle 31 extends forwards of the clutch and is coupled to an elongate rotatable socket 32. The socket 32 has a hexagonal socket portion 33 at its front end and an external screw thread 34. The socket 32 is mounted for rotation within the housing and its front end is set back from the socket 30.

A sleeve 35 is mounted on the housing 26, 27, so as to be axially slidable but not angularly movable relative to the housing. The sleeve 35 extends forwards of the front end of the socket 30 and has a nylon or other plastics end cap 36 snap fitted to its front end.

A clamp extraction operating member in the form of a manually operable trigger 37 is pivotably connected to the sleeve by a pin 38. The trigger is formed with a part female screw thread 39. The front end part 27 of the housing is provided with an elongate slot 40 so that the screw thread 39 can be brought into engagement with the external screw thread 34 on the socket 30 when the trigger is pivoted against the force of a return spring 41.

The elongate socket 30 has six circumferentially spaced apertures 42 near its front end. The apertures are located at the intersections of the six sides of the socket 30. A baIl 43 is located in each aperture and has a diameter slightly larger than the through length of the aperture. The sleeve 35 has an annular groove 44 in its inner wall. The groove 44 is aligned with the apertures 42 when the sleeve 35 is in its rearmost position relative to the housing 26, 27.

The arrangement of the socket 30, the socket portion 33 and the apertures 42 is such that when a clamp 10 is inserted into the front of the tool with the nut 19 unscrewed and the body 15 drawn back the nut fits into the socket portion 1 6 and the clamp body fits into the socket 30 with the front edge of the hexagonal portion 1 6 rearwardly of the apertures 42. It is important that the pitch of the screw thread 34 on the socket 30 is finer than the pitch of the screwthread on the clamp stem 11 for a purpose which will be explained later.

To insert one of the clamps 10 into for example aligned holes in two metal skins 45, 46 with an adhesive layer 47 interposed between the skins, the clamp (in the unscrewed state) is inserted into the front of the tool. As the sleeve 35 is in its rearmost position the balls 43 move radially outwards into the groove 44 to allow the hexagonal portion 16 of the clamp body to pass them. Forward rotation of the motor 28 is selected, and the collet legs 12, 13 of the clamp are passed through the holes in the skins 45, 46.

The motor is then energised by pressing a button 48 on the pistol grip, but the trigger 37 is not operated. The nut 1 9 is screwed down by rotation of the socket portion 33. This in turn moves the clamp body 15, and with it the separator 16, forwards, the body 1 5 being guided by the socket 30. The separator 1 6 opens up the heads 14 of the collet legs and the two skins are clamped between the heads 1 4 and the cylindrical portion 18 of the clamp body (see Figure 2), the clutch 29 slipping when a predetermined torque is reached.

The tool is then switched off manually and withdrawn from the clamp.

To extract the clamp 10 from the holes, reverse rotation of the motor 28 is selected. The tool is placed over the clamp. The trigger 37 is manually depressed and held, to engage its part female screw thread 39 with the external screwthread 34 on the socket 30. The motor is then energised by depressing button 48. The socket portion 33 unscrews the nut 19 and at the same time the sleeve 35 is screwed forwards locking the six balls 43 in a radially inwards position. These balls are aligned with the corners of the hexagonal portion 1 6 of the clamp body and prevent the latter from coming out of engagement with the socket 30.

The sleeve 35 pushes via the nylon end cap 36 against the skins 45, 46, hence pulling the clamp out of the holes (see Figure 3). As previously mentioned the pitch of the screwthread 34 or the socket 30 is finer than the pitch of the screwthread on the clamp stem 11, and this ensures that the clamp is fully released before it is extracted. Moreover, the ratchet clutch in this direction is locked, preventing it from slipping, to ensure maximum torque is available to release the clamp and push the sleeve 35 forwards. The sleeve is then slid back manually and the clamp removed from the tool.

If the tool is to be used with a robot the trigger 37 can be operated by an air cylinder and the sleeve 35 can be provided with a return spring.

The tool can be used to insert and extract other clamps similar but not identical to the clamp 10.

For instance, one such clamp does not have the spring 22 and another has three collet legs.

Claims (11)

1. A tool for inserting and extracting a clamp of the type hereinbefore defined, the tool comprising a housing having a front end for receiving the clamp and a rear end, a fixed socket at the front end of the housing engageable with the body of the clamp to prevent rotation of the clamp body relative to the housing, a rotatable socket mounted in the housing and engageable with the nut of the clamp, the rotatable socket having an external screwthread, a reversible motor for rotating the rotatable socket, the motor being rotatable in one direction to insert the clamp and in the opposite direction to extract the clamp, a sleeve axially slidably mounted on the housing, a clamp extraction operating member having a part thread thereon and mounted on the sleeve for movement between a first inoperative position and a second position in which the part thread engages the external thread on the rotatable socket such that the sleeve is moved forwards when the motor is rotating in said opposite direction, and locking means operable by forwards movement of the sleeve to hold the clamp in the fixed socket.

2. The tool of claim 1, wherein a ratchet clutch is provided between the motor and the rotatable socket and is arranged to slip at a predetermined torque when the motor is rotating in said one direction but not to slip when the motor is rotating in said opposite direction.

3. The tool of claim 1 or claim 2, wherein the locking means comprises one or more apertures in the fixed socket, a locking element in the or each aperture and one or more internal grooves in the sleeve and aligned with the aperture or apertures in the fixed socket when the sleeve is in a rearmost position to allow the locking element(s) to move radially outwards, the arrangement being such that forwards movement of the sleeve takes the groove or grooves out of alignment with the aperture or apertures and the locking element(s) is/are constrained by the sleeve to move radially inwards.

4. The tool of claim 3, wherein the or each locking element is a ball.

5. The tool of any one of the preceding claims, wherein the clamp extraction operating member is manually operable and is urged away from its second position by a spring.

6. The tool of any one of claims 1-4, wherein the clamp extraction operating member is operable by fluid pressure operated means.

7. The tool of any one of the preceding claims, wherein the sleeve has an associated return spring.

8. The tool of any one of the preceding claims, wherein the pitch of the thread on the rotatable socket is arranged to be finer than the pitch of the thread on the clamp.

9. The tool of any one of the preceding claims, wherein the motor is an air motor.

10. The tool of any one of the preceding claims, wherein the sleeve has a plastics end piece at its front end.

11. A power tool for inserting and extracting a skin clamp, substantially as hereinbefore described with reference to and as shown in Figures 2 and 3 of the accompanying drawings.