GB2151964A

GB2151964A - Improved screw driving tool

Info

Publication number: GB2151964A
Application number: GB08334387A
Authority: GB
Inventors: Brian Ronald Tompkins; Julien Lankry
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-12-23
Filing date: 1983-12-23
Publication date: 1985-07-31
Also published as: GB2151964B; GB8334387D0

Abstract

A screw driver attachment (10) for use with a drilling machine comprises an elongate member (11) of which one end (12) is received in the jaws of the machine. The other end (13) of the elongate member (11) has a recess (14) therein housing a clutch device (17, 40, 42) and receiving a screw driving member (15) therein. Screw retaining sleeves (18, 19) are mounted on the elongate member (11) so as to be slidable longitudinally thereof between two positions in each of which the clutch device (17, 40, 42) disengages the drive from the elongate member (11) to the screw driving member (15) whilst between those positions retaining balls (17) located in the eiongate member (11) are forced radially inwardly by the inner retaining sleeve (18) so as to engage a flat part (41) of the screw driving member (15) and transmit the rotary drive thereto. <IMAGE>

Description

SPECIFICATION Improved screw driving tool This invention relates to screw driving tools.

In addition to the use of screwdrivers by hand, it is known to use power tools for the above purpose.

The use of power tools in this context is particularly advantageous in the event that a large number of screws are to be tightened or removed, since in such a case the use of a hand screwdriver can be arduous and cause discomfort to the person concerned.

However, particular difficulty is experienced in the use of power tools in the case of inserting and tightening screws, for example wood screws, into a workpiece or fixture. This is due to the lack of control exercisable by the operator of the power tool on the retention of the tool in or around the screw head, and in respect of the direction of intended insertion of the screw into the workpiece or fixture. Also such power tools as have been proposed are expensive and unless they are used frequently such expense is not justified.

There is described in British Patent Publication NO. 2088264 a screw driving device whereby the abovementioned operation can be performed with the use of a power tool in a manner not having the aforementioned disadvantages, or at least in which such disadvantages are substantially reduced. It is an object of the present invention to provide a screw driving tool which is an improvement on that described in the aforementioned published specification.

The invention provides a device for use in rotating a screw or the like comprising an elongate member having one end thereof adapted to receive a screw driving member and the other end adapted to be received in the jaws of a rotary machine, a screw driving member received by said one end of said elongate member, a screw retaining means disposed around said elongate member and said driving member and movable longitudinally relative thereto, and clutch means disposed between said elongate member and said screw driving member.

By screw or the like is intended to include screws, for example wood screws, bolts, studs, nuts or the like having a screw threaded portion and having a slot, a recess or an outer form adapted to receive a screwdriver, Allen (R.T.M.) key or spanner for the purpose of tightening or removal of the screw.

Preferably said retaining means is resiliently biased longitudinally of said elongate member.

The said screw driving member may comprise a screwdriver bit or blade, an Allen (R.T.M.) key or plug, or a socket spanner device.

The said other end of said elongate member may be of circular or hexagonal cross-section.

The screw driving member may comprise a screw engaging part and a body part, and said body part may have at least one flat portion around its periphery. Preferably said body part is hexagonal in cross-section.

The clutch means may comprise at least one engaging member located in said elongate member and movable radially thereof. Preferably three engaging members are provided disposed equi-spaced around the axis of said elongate member.

Said retaining means may be movable longitudinally of said elongate member between two positions, in each of which the or each said engaging member is able to move radially outwardly relative to said elongate member and disengage said screw driving member, whilst when said retaining means is disposed between said two positions said retaining means retains the or each engaging member radially inwardly relative to said elongate member so as to engage said screw driving member. The or each engaging member may comprise a ball.

Afurther ball may be disposed between an end of said body part of said screw driving member and an end of an axial bore in said one end of said elongate member in which bore said screw driving member is received.

Said retaining means may comprise inner and outer sleeves which are relatively movable axially of said device. Said inner sleeve may have at least one aperture therein and a movable member retained in the or each aperture for movement therein radially of said inner sleeve. Preferably a plurality of movable members are provided disposed equi-spaced around the axis of said inner sleeve. The or each movable member may comprise a ball. The outer sleeve may comprise an inner conical surface which in use is engaged by the or each movable member.

The device may comprise stop means disposed on said elongate member so as to limit the movement of said retaining means in a direction towards said other end. Said stop means may comprise a cap, the position of which is adjustable axially of said elongate member. The retaining means and the stop means may be resiliently biassed away from each other.

The invention will now be further described with reference to the accompanying drawings in which: Figures 1 to 3 are half-sectional elevations of one embodiment.

Referring now to Figure 1 there is shown a tool 10 comprising an elongate member 11 having one end thereof in the form of a shaft 12 which is of circular or hexagonal cross-section and may be received in the jaws of a drilling machine (not shown) in conventional manner. The other end 13 of elongate member 11 is provided with an axially extending bore 14 of circular cross-section and in which a bit 15 is received. The bit 15 shown in Figure lisa flat bladed screwdriver and may be replaced by a cruciform screwdriver bit or an allen key bit as required by a screw (not shown) to be tigthened or unscrewed.

Inner 18, and outer 19, guide sleeves surround the elongate member 11 and bit 15 and are movable axially relative thereto and relative to each other. A cap 20 is mounted on elongate member 11 and is positionally adjustable axially thereof by means of spigots 21,which are provided on a sleeve 16 secured to elongate member 11 by a pin 35, engaging in respective ones of a plurality of internal grooves 22 axially extending by differing amounts in cap 20 (see Figures 2 and 3). Alternatively cap 20 may be screwed onto sleeve 16. A spring 23 is located in an annular recess 24 in cap 20 and reacts against a washer 25 which in turn abuts outer sleeve 19, whereby cap 20 and outer sleeve 19 are resiliently biassed away from each other. Internal circlip 26 in outer sleeve 19 abutting outer circlip 27 on sleeve 16 limits the movement of outer sleeve 19 away from cap 20.A spring 28 is disposed within outer sleeve 19 to react between circlip 27 and an internal rib 29 so as to bias outer sleeve 19 away from the shaft 12.

If cap 20 is screwed to sleeve 16 either one of spring 23 or 28 is not required. Inner sleeve 18 is resiliently biassed away from shaft 12 by a spring 30 and is limited in its axial movement by a rib 31 abutting an internal conical surface 32 of outer sleeve 19. The conical surface 32 is stepped at 38 so as to accommodate a wide range of screw shank diameters with which the tool 10 may be used. Inner sleeve 18 has four apertures 33 in which balls 34 are retained, the apertures 33 having a lip 36 at the inner edge to prevent the balls 34 from passing therethrough and also maintaining separation of the balls 34 when in their innermost position and not retaining a screw within the tool 10. In this way also a wide range of sizes of screw can be accommodated by the tool 10.

Before use of the tool 10 it is in a configuration as shown in Figure 1 with inner sleeve 18 protruding from outer sleeve 19. By pushing inner sleeve 18 into outer sleeve 19 against the force of spring 30 the head of a screw may be inserted into the tool 10. The balls 34 may move radially outwardly along conical surface 32 to allow the head of a screwto pass therebetween and to engage bit 15. The tool 10 will then return substantially to the configuration as shown in Figure 1, since the spring 30 will push inner sleeve 18 away from shaft 12 so that balls 34 are forced radially inwardly to engage the shank of the screw, the head of the screw being retained in contact with bit 15.In this configuration the bit engaging balls 17, which are located in the end part 13 of elongate member 11, can move radially outwardly so that the shaft 12 can rotate relative to bit 15. A ball bearing 39 is located between the bottom of the bore 14 and the end of bit 15 to faciliate such relative rotation.

The screw is then offered to the workpiece to commence screwing. During this operation the balls 34 support and securely locate the screw. The inner sleeve 18 is drawn by hand towards the shaft 12 so thatthe bit engaging balls 17 are forced radially inwardly by the inner end 40 of sleeve 18. The bit engaging balls 17 then engage the flat surfaces of the hexagonal body part 41 of bit 15 to cause the bit 15 to rotate with the shaft 12.

The outer end 37 of inner sleeve 18 will eventually abut the workpiece and further screwing causes the inner sleeve 18to be retracted into outer sleeve 19 and relative to elongate member 11. Thereafter outer sleeve 19 will also abut the workpiece and both sleeves 18,19 are forced toward shaft 12. After further insertion of the screw into the workpiece washer 25 abuts cover 20 as shown in Figure 2.

During the second phase of the screwing operation the retraction of inner sleeve 18 into outer sleeve 19 allows the balls 34 to move radially outwardly so that the screw is released and the head of the screw can again pass between balls 34.

When the situation as shown in Figure 2 is reached the bit engaging balls 17 become aligned with the annular recess 42 and can move radially outwardly into the recess 42, thereby disengaging the hexagonal body part 41 of bit 15 and allowing relative rotation between the shaft 12 and the bit 15. By this means screwing will cease. The axial location of cap 20 relative to sleeve 16 determines the amount of retraction of sleeves 18,19 and hence the height of the head of the screw relative to the workpiece at the termination of screwing. By adjustment of cap 20 axially of sleeve 16 it can be arranged accurately, easily and conveniently, that the head of the screw be proud of, flush with or recessed relative to the surface of the workpiece.In Figure 1 the cap 20 is shown in a position of adjustment for which the screw head will remain slightly proud of the surface of the workpiece when screwing terminates, whereas in Figure 2 the cap 20 is shown in a position of adjustment for which the screw head will be recessed into the workpiece by a small amount.

By means of the invention a large range of sizes of screw may be securely retained and guided by the tool 10 during a screwing or unscrewing operation, the commencement and termination of the screwing operation being automatic, smooth and free from snatching.

When using a drilling machine which has a reverse drive facility or when using a drilling machine with a drive reversing attachment as described in British patent application No.8324518 (Serial No 2146563), a screw may be withdrawn simply in the following manner. As shown in Figure 3 a slightly longer bit 15athan previously used is located in the tool 10 and the cap 20 is put in a position of adjustment such that when the sleeves 18 and 19 are pressed against the workpiecethe bit-engaging balls 17 are not aligned with annular recess 42. In consequence, the bit engaging balls 17 are forced radially inwardly by the tubular inner part 40 of sleeve 18 so as to engage the hexagonal body part 41 of the bit 15a. The bit 15a is thereby caused to rotate with the shaft 12 and the screw may be withdrawn from the workpiece. The bit 15a may be for example 2mm longer than the bit 15 used for inserting the screw.

Claims

1. A device for rotating a screwthreaded fastener, said device comprising an elongate member having one end thereof adapted to be received in the jaws of a rotary machine, and a recess in the other end thereof, a screw driving member removably engageable within said recess, clutch means dis posed within said recess between said elongate member and said screw driving member, said clutch means being adapted to prevent or to allow relative rotation between said elongate member and said screw driving member, and retaining means slidably mounted on said elongate member so as to be movable longitudinally relative thereto.

2. A device according to claim 1 wherein said retaining means comprises inner and outer sleeve members mounted on said elongate member so as to be slidable relative thereto and to each other, at least one movable member located by said inner sleeve member but movable radially thereof and a recess in said outer sleeve member adapted to receive said movable member, and first and second spring means operable to bias said inner and outer sleeve members respectively longitudinally of said elongate member away from said one end.

3. A device according to claim 1 or claim 2 further comprising adjustable stop means disposed on said elongate member so as to limit the movement of said retaining means in a direction towards said one end.

4. A device according to any one of claims 1 to 3 wherein said driving member comprises a screwdriver blade.

5. A device according to any one of claims 1 to 3 wherein said driving member comprises an allen key.

6. A device according to any one of claims 1 to 5 wherein said one end is of circular cross-section.

7. A device according to any one of claims 1 to 5 wherein said one end is of hexagonal cross-section.

8. A device according to any one of claims 1 to 7 wherein said recess in said elongate member is adapted to receive a head of a screw therein.

9. A device according to claim 2 or any claim dependent thereon wherein said inner sleeve member has at least one aperture therein, a movable member being retained in the or each aperture for movement therein radially of said device.

10. A device according to claim 9 wherein said inner sleeve member has therein a plurality of equi-angularly spaced apertures, each aperture having a lip at the innermost end thereof whereby said movable members are prevented from passing through said apertures and from mutual contact when in their innermost positions.

11. A device according to claim 9 or claim 10 wherein said outer sleeve member comprises an inner conical surface which in use is engaged by the or each movable member.

12. A device according to claim 11 wherein said conical surface is stepped.

13. A device according to claim 3 or any claim dependent thereon wherein said stop means comprises a cap the position of which is adjustable axially of said elongate member.

14. A device according to claim 13 wherein said retaining means and said stop means are resiliently biased away from each other.

15. A device according to any one of claims 1 to 14 wherein said screw driving member comprises a screw engaging part and a body part, said body part having at least one flat portion around its periphery.

16. A device according to claim 15 wherein said body part is hexagonal in cross-section.

17. A device according to claim 15 or claim 16 wherein said clutch means comprises at least one engaging member located in said elongate member and movable radially thereof.

18. A device according to claim 17 wherein said clutch means comprises three engaging members equi-spaced around the axis of said elongate member.

19. A device according to claim 17 or claim 18 wherein said retaining means is movable longitudinally elongate member between two positions, in each of which the or each engaging member is able to move radially outwardly relative to said elongate member and disengage said screw driving member, whilst between said positions said retaining means retains the or each engaging member radially inwardly relative to said elongate member so as to engage said screw driving member.

20. A device according to any one of claims 17 to 19 wherein the or each engaging member comprises a ball.

21. A device according to claim 20 comprising a further ball disposed between an end of said body part and an end of said recess in said elongate member.

22. A device for rotating a screwthreaded fastener substantially as hereinbefore described with reference to and as illustrated in any one of the various figures of the accompanying drawings.