GB2178680A - Driving tools for screw-threaded fasteners - Google Patents

Abstract

A driving tool for rotating a nut or bolt is connectible to a power drill (11) and includes a nut or bolt engaging member (12). There is provided between the power drill (11) and the engaging member (12) a reverse mechanism (13) for determining the direction of rotation of the engaging member (12) and a torque-adjusting mechanism (71) including clutch means rotatably associated with the reverse mechanism. The reverse mechanism (13) comprises a planetary gear system, whereof the planet carrier (46) can be locked by a control mechanism (14) to effect rotation of the engaging member (12) in an unscrewing sense (i.e. reverse rotation) or to be released to effect rotation of the engaging member (12) in a tightening sense (i.e. forwards rotation). The engaging member (12) has jaws (29) positionally adjustable in a radial direction to accommodate differing sizes of nut or bolt. <IMAGE>

Description

SPECIFICATION Driving tools for screw-threaded fasteners This invention relates to tools, and in particular to tools for use in tightening or removing screwthreaded fasteners such, for example, as screws, bolts, nuts or the like of the type having a shaped outer surface or head for engagement by a spanner or wrench (hereinafter referred to as "nuts and bolts").

In addition to the use of spanners or wrenches by hand, it is known to use power tools for the above purpose. The use of power tools is particularly advantageous in the event that a large number of nuts and bolts are to be tightened or removed, since in such a case the use of hand tools can be arduous and cause discomfort to the person concerned. In addition the applied torque can be more readily controlled by use of a power tool than when tightening by hand unless a specially adapted torque wrench is used. It is known to provide such power tools with a driven driving member of square or hexagonal cross-section to receive an appropriately sized one of a plurality of sockets for each nut or bolt to be tightened or removed.However frequent changing of the size of socket can be tiresome and since there are many types of nuts and bolts having differing head dimensions, several ranges of sockets are required in order to ensure use of the correctly sized socket with any particular nut or bolt. Also such power tools as have been proposed are expensive and unless they are used frequently such expense is not justified.

It is an object of the present invention to provide an improved driving tool for use with a rotary machine which avoids the aforementioned disadvantages.

According to the present invention there is provided a driving tool for rotating a screwthreaded fastener, the tool having one end thereof adapted to be received in a rotary machine and a fastener engaging member at the other end thereof, comprising a reversing mechanism for determining the direction of rotation of the fastener engaging member, including clutch means rotatably associated with said reversing mechanism, and said fastener engaging member comprising a plurality of jaws mounted on a driver part for radial movement relative thereto and adjustment means operable to positionally adjust said jaws radially of said driver part.

Preferably said driving tool also comprises a torque adjusting mechanism.

One embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of a driving tool for rotating a nut or bolt, Fig. 2 is a sectional view of the reversing and torque adjustment mechanism of the driving tool to an enlarged scale, Fig. 3 is a detail view in transverse section of the mechanism of Fig. 2, Fig. 4 is a detail view of various components of the reversing and torque-adjustment mechanism of Fig. 2, Fig. 5 is a plan view of the manual adjustment device for the mechanism of Fig. 2, Fig. 6 is a side elevation of the device of Fig. 5, and, Fig. 7 is a half-sectional side elevation of the fastener engaging mechanism of the driving tool to an enlarged scale.

Referring to Figs. 1 to 6, the screw rotating device or tool comprises three assemblies drivingly connected to the chuck or jaws 10 of a power drilling machine generally indicated at 11, for example a hand-held power drill.

The three assemblies comprise a fastener engaging mechanism 12, a reversing mechanism 13 for determining the direction and rotational speed of screwing, and an adjustment mechanism 14 which serves to control the mechanism 13.

Reference is now made to the mechanism 13, which is in effect a forward and reverse planetary gear and a torque adjustment, and in particular to Figs. 2 to 4.

The mechanism 13 comprises an inner sleeve 40 having at one end a closing plate 41 provided with a central opening surrounded by equi-angularly spaced openings disposed radially outwardly of the central opening.

A drive shaft 42 with an outer squared end 43 extends into the inner sleeve 40 and has a gear wheel 44 mounted thereon, the squared end 43 being received in the chuck or jaws 10 of the power drill 11.

The inner sleeve 40 is peripherally internally geared as indicated at 45 at its end adjacent the closing plate 41.

Between the closing plate 41 and the adjacent end of the inner sleeve 40 is a gear support plate 46 having openings corresponding to those in the closing plate 41. Axially spaced from the gear support plate 46 and the closing plate 41 is a second gear support plate 47 having complementary openings to those of the support plate 46.

The circumference of the gear support plate 46 is provided with three equi-angularly spaced cut-outs or recesses 48.

The inner sleeve 40 has on its outer circumference two axially spaced grooves 49, is formed with a radial hole 50 intermediate its ends, and is externally slotted as indicated at 51 at the closing plate end.

Three rotatable shafts or spindles 52 each carrying a gearwheel 53 bridge and connect the gear support plates 46 and 47, the gear wheels 53 meshing with the central gear wheel 44 and the gear annulus 45 of the inner sleeve 40. Thus the se gears 44,45 and 53 constitute a planetary gear. The spindles 52 are received in the three equi-angularly spaced openings in the support plates 46 and 47.

The support plates 46 and 47 are spaced apart by bushes 54 within which are secured headed fastening bolts 55 extending through complementary holes in the closing plate 41, the gear support plate 46 and the gear support plate 47, the holes in the iatter having screw-threads therein.

An outer sleeve 56 surrounds and is axially movable relative to the inner sleeve 40. The outer sleeve 56 has at each end a slot 57 within which is received an end of a flat tension spring 58 having a central dimple 59 engageable in one of the grooves 49 of the inner sleeve 40. The outer sleeve 56 has a slot 60 intermediate its ends and aligned with the end slots 57. Thus, the central portion of the flat tension spring 57 registers with the slot 59. The outer sleeve 56 is slotted as indicated at 61 at a location diametrically opposed to the end slots 57 and the intermediate slot 60, and at said location is formed with an inner key 62 engageable in the slot 51 of the inner sleeve 40.

Finally, the outer sleeve 56 has on its outer surface a pair of etched marker lines 63.

A bearing plate 64 abuts the gear support plate 47, and abutting the plate 64 is a torque limit bearing plate 65 having a circumferential projection 66 keying it to the inner sleeve 40.

This torque limit bearing plate 65 has three equi-angularly spaced holes each of which accommodates a ball bearing 67.

An output drive shaft 68 having an integral frusto-conical bearing plate 69 is located within the inner sleeve 40, the bearing plate 69 having three radial grooves 70 which at their inner ends engage the ball bearings 67.

The bearing plates 65 and 69, and ball bearing 67, thus constitute a clutch.

The inner sleeve 40 is closed by a screw cap 71 through which the output drive shaft 68 extends, a compression spring 72 within the cap 71 surrounding the output drive shaft 68 and loading the bearing plate 69 against the ball bearings 67.

A retaining spring 72a engages the outer surface of the cap 71 and the inner surface of the inner sleeve 40 to resist egress of the cap 71 from the inner sleeve.

It will be manifest that the torque applied during screwing or unscrewing can be varied by adjusting the screw cap 71 relative to the inner sleeve 40, this being of particular advantage if over-tightening of a nut or bolt is to be avoided.

The output drive shaft 68 has a hexagonal blind bore 73 for receiving the end 16 of the shaft 15 of the mechanism 12, which shaft 15 is releasably secured in position by a ball bearing 74 carried by the shaft 68 and a sur rounding clip or sleeve 75 which forces the ball bearing 74 against the shaft 15.

The outer sleeve 56 is, in fact, a gear selector sleeve which is used to determine forward or reverse gear and here it should be noted that the gear ratios are selected to give a reverse drive which is one third the speed of the forward drive. The gearing and gear ratios could be varied to provide a different lesser speed reverse drive.

Before describing the selection of forward or reverse gear, the control mechanism 14 will be described, with particular reference to Figs.

5 and 6.

This mechanism 14 comprises a U-bolt 80 by which the mechanism is secured to the power drill 11, the limbs of the U-bolt 80 being connected by a yoke 81 on which is pivoted a support frame 82. A tension leaf spring 83 interconnects the yoke 81 and the support frame 82 and serves normally to urge the frame 82 to a position aligned with yoke 81, shown in full lines in Fig. 6.

The support frame 82 carries at its yokeremote end an adjusting plate or finger 84 which is perpendicular to the support frame 82 and whose position relative to the support frame 82 is adjustable by means of complementary slots 85,86 in the support frame 82 and the adjusting plate 84 respectively and a securing bolt 87.

To select reverse drive for unscrewing, the outer sleeve 56 is pushed forwards relative to the inner sleeve 40, i.e. towards the mechanism 12, and the support frame 82 is pivoted to the perpendicular position, shown in Fig. 1 and in dashed lines in Fig. 6, to engage the adjusting plate or finger 84 in one of the slots of the gear support plate 46. This holds the gear support plates 46 and 47 (the planet carrier) and gears 53 against bodily rotation, thereby causing the annulus gear 45, the inner and outer sleeves 40 and 56, the clutch 65, 67, 69 and the output drive shaft 68 to rotate in counter direction to the direction of rotation of the shaft 43, and at one third the speed thereof.

To select forward drive for screwing, the support frame 82 and the adjusting finger or plate 84 are pivoted to the aforementioned aligned position. The marker lines 63 on the outer sleeve 56 are aligned with the cut-outs or slots 48 on the gear support plate 46, and the outer sleeve 56 is slid towards the chuck 10 to cover these slots 48. In this condition, the gear support plates 46 and 47 and the gears 53 can rotate bodily to cause the drive from the shaft 46 to be transmitted to the output drive shaft 68, which then rotates in the same sense of rotation and at the same speed as the drive shaft 46.

The dimple 59 on the flat tension spring 58 is received in the appropriate groove 49 on the inner sleeve 40 to locate the outer sleeve 56 in a position where it exposes the re cesses or slots 48 or a position where it con ceals the latter.

Reference is now made to the fastener engaging mechanism 12, and, in particular to Fig. 7. The mechanism 12 comprises a driver part or shaft 15 having one end 16 thereof of hexagonal cross-section so as to be received and retained in bore 73 of the output drive shaft 68 of the mechanism 13. The shaft 15 has a first central part 17 of relatively large diameter and a second central part 18 of reduced diameter relative to the first central part 17. At the other end of the shaft 15 from the end 16 is a relatively small diameter end 24.

The face 19 between the first and second central parts 17, 18 is of helical form except for a longitudinally extending stop face 20.

The shaft 15 fits within a sleeve 21 which has a correspondingly stepped bore 25 at one end thereof providing a helically formed step face 22 and a longitudinally extending stop face 23. In the other end of sleeve 21 is a conical bore 26. The second central part 18 has three equi-angularly spaced radially extending slots 27 in each of which a locating end 28 of a jaw 29, and a three pronged leaf spring 30 biasses the jaws 29 radially outwardly. Each jaw 29 has a conical cam surface 31, the cone angle of bore 26 and surfaces 31 being the same. A ring of ball bearings 32 is located in a recess in conical bore 26 so that the ball bearings bear on the conical surfaces 31 of the jaws 29.

On assembly the sleeve 21 is placed over the shaft 15 and rotated until helical surfaces 19,22 and stop faces 20,23 abut each other.

In this position the spring 30 and the jaws 29 can be inserted into slots 27 through the gap between the conical bore 26 of sleeve 21 and the smaller diameter end 24 of shaft 15. This position is the widest possible adjustment of the jaws 29. Rotation of the sleeve 21 causes its movement longitudinally of the shaft 15 due to the interaction of helical faces 19,22 and the bearings 32 to force the jaws 29 radially inwardly against the force of the spring 30. By this means any size of nut or bolt head within the range of adjustment of the mechanism 12 can be gripped by the jaws 29 and screwing or unscrewing effected dependent upon the selection of rotation direction using the mechanisms 13,14. The friction between the surfaces 19 and 22 and between the bore 25 and the outer surfaces of central parts 17 and 18 prevent opening of the jaws 29 in use. Alternatively a ratchet or "clickstop" arrangement may be provided. Rotation of the sleeve 21, after release of any ratchet or click-stop mechanism if provided and required, allows the spring 30 to force the jaws 29 radially outwardly to release the nut or bolt head, the bearings 32 ensuring a nonjamming operation.

The device or tool according to the present invention can readily be fitted to any power drill; it can accommodate any sized nuts and bolts within its range of adjustment, and a nut or bolt automatically ceases to be driven when it is sufficiently tightened in accordance with a pre-set torque limit.

Claims (25)

1. A driving tool for rotating a screwthreaded fastener the tool having at one end thereof a shaft adapted to be received in a rotary machine, and a fastener engaging member at the other end thereof, comprising a reversing mechanism for determining the direction of the fastener engaging member, and said fastener engaging member comprising a plurality of jaws mounted on a driver part for radial movement relative thereto and adjustment means operable to positionally adjust said jaws radially of said driver part.

2. A tool according to claim 1 further comprising clutch means rotatably associated with said reversing mechanism.

3. A tool according to claim 2 wherein said clutch means comprises a torque adjusting mechanism.

4. A tool as claimed in any one of claims 1 to 3 in which the reversing mechanism comprises a planetary gear system, whereof the planet carrier is adapted to be locked to effect rotation of the fastener engaging member in an unscrewing sense (i. e. reverse rotation) or to be released to effect rotation of the fastener engaging member in a screwing sense (i.e. forwards rotation).

5. A tool as claimed in claim 4, in which the gear ratios of the planetary gear system are selected so that the speed of reverse rotation is less than that of forwards rotation.

6. A tool as claimed in claim 5, in which the gear ratios of the planetary gear system are selected so that the speed of reverse rotation is one third of that of forwards rotation.

7. A tool as claimed in any one of claims 4 to 6, in which the planetary gear system is housed in an inner sleeve whereof part of the inner surface is toothed to provide the annulus of the planetary gear system.

8. A tool as claimed in claim 7 in which the planetary gear carrier comprises a pair of plates between which the planet gears are supported with one of the plates being external of the inner sleeve and having at least one peripheral slot or recess to receive a locking element.

9. A tool as claimed in claim 8 comprising an outer sleeve surrounding the inner sleeve and axially movable relative thereto to expose or conceal said peripheral slots or recesses.

10. A tool as claimed in claim 9, in which the outer sleeve has an internal dimple or projection adapted to seat in one of two axiallyspaced grooves on the outer surface of the inner sleeve in either the slot or recess exposing or concealing position.

11. A tool as claimed in any one of claims 4 to 10, in which the sun wheel of the planetary gear system is carried by said shaft.

12. A tool as claimed in any one of claims 7 to 11 when dependent on claim 2, in which the clutch means comprising a pair of plates housed within the inner sleeve, the plates being drivingly connectable by balls carried by one plate and engaging the other end with the ball-carrying plate being keyed to the inner sleeve.

13. A tool as claimed in claim 12 when dependent on claim 3, in which a torque-adjusting cap is connected into the inner sleeve, a clutch-loading spring being disposed between the cap and the other plate, a relative movement between the cap and the inner sleeve varying said loading and consequently the torque applied to the fastener engaging member.

14. A tool as claimed in clalm 13, in which the other clutch plate has connected thereto an output drive shaft which projects out of the torque-adjusting cap.

15. A tool as claimed in claim 14, in which the output drive shaft is hollow removably to receive the fastener engaging member.

16. A tool as claimed in claim 8 or any claim dependent thereon in combination with a control mechanism detachably connectible with the rotary machine and comprising an arm or finger adapted to be moved between a position clear of the planetary gear system (forwards rotation) and a position where the arm or finger engages in said peripheral slot or recess in the planet gear carrier to lock same against bodily rotation (reverse rotation).

17. A tool as claimed in claim 16, in which the arm or finger is carried on a support plate pivoted to a clamp adapted to be detachably connected on a stationary part of the rotary machine.

18. A tool as claimed in claim 17, in which the arm or finger is adjustably mounted on the support plate.

19. A tool as claimed in claim 17 or claim 18 in which the support plate is spring loaded relative to the clamp to the position clear of the planetary gear system.

20. A tool according to any one of claims 1 to 19 wherein said driver part of said fastener engaging member comprises a stepped outer peripheral surface having a first helical face forming a step thereon and a longitudinally extending first stop surface between opposed ends of said first helical face, and said adjustment means comprises a sleeve rotatably mounted on said driver part, said sleeve having a stepped bore therein with a second helical face forming a step therein and a longitudinally extending second stop surface between opposed ends of said second helical face.

21. A tool according to claim 20 wherein said driver part has a plurality of radial slots therein, each of which is adapted to receive a locating end of a respective jaw.

22. A tool according to claim 20 or claim 21, wherein said sleeve has a conical bore therein and each of said jaws has a conical cam surface.

23. A tool according to claim 22, wherein a ring of ball bearings is disposed between said conical bore and said conical cam surfaces.

24. A tool according to any one of claims 20 to 23 wherein a spring having a plurality of arms is mounted in said driver part and is operable to bias said jaws radially outwardly.

25. A tool for rotating a screw-threaded fastener substantially as hereinbefore described with reference to the accompanying drawings.