A gripping tool

The invention relates to a gripping tool of the kind that is defined in the preamble of claim 1.

Gripping tools are previously known, which have a tool body having a first fixed handle branch, a fixed clamping jaw, a movable clamping jaw, which is displaceable toward and away from the fixed clamping jaw by means of a slide guide, a movable handle branch, which is movable toward and away from the fixed handle branch, and a transmission that drives the movable clamping jaw toward the fixed clamping jaw and that is connected between the branches in order to afford a selected force ratio so that the tool can apply a higher gripping force against an object between the clamping jaws, when the branches are brought together by a relatively small force. It is also known to form the transmission so that it, in the beginning of the bringing together of the branches, affords the movable clamping jaw a quick movement by a low force, and subsequently to afford a higher force ratio.

A drawback of previously known gripping tools is that the transmission changes over into the strongly force-changing state thereof at varying distances between the branches, depending on the size of the object squeezed-in between the clamping jaws.

Therefore, an object of the invention is to provide a grip- ping tool, by means of which the transmission is activated into the force-changing state thereof at one and the same distance between the handle branches, independently of the size of the gripped object. In this way, the ergonomics of the tool is improved, since the force application by the hand against the tool branches becomes uniform and independent of the distance between the clamping jaws, when the

transmission is activated into the force-changing state thereof.

An additional object is to provide a simple and robust con- struction for such a gripping tool.

The objects are entirely or partly attained by the invention.

The invention is defined in the appended independent claim.

Embodiments of the invention are defined in the appended dependent claims.

In the following, the invention will be described by way of examples, reference being made to the appended drawing.

Fig. 1 schematically shows an oblique perspective view of a gripping tool according to the invention.

Fig. 2 shows a slider, which is carried by the movable clamping jaw in the tool according to Fig. 1.

Fig. 3 shows schematically and in perspective a rack that is carried by the slider according to Fig. 1.

Fig. 4 shows, in a view corresponding to Fig. 1, a variant of the gripping tool.

Fig. 1 illustrates a tool body 10, which has a fixed handle branch 48 and a fixed clamping jaw 11. The body carries a slide guide 4 for a movable clamping jaw 3, which is dis- placeable toward and away from the fixed clamping jaw 11. The clamping jaws 3, 11 have mutually facing, preferably parallel and plane surfaces, between which a object 12 can be gripped and squeezed-in. A movable tool branch 5 is par ^¬ allel to the handle branch 48 and is guided into parallel

displacement by spring legs 1, 2. Each of the spring legs 1, 2 are shown to comprise a sleeve, which is shown carried by the branch 5 and which at the opposite end thereof receives a bar carried by the branch 48, a weak spring 71 and 72, respectively, being received in the sleeve. The springs 71, 72 bias the branch 5 to an outer end position by a weak spring force.

The branch 5 is also coupled to the movable jaw 3 by means of a spring leg 6 containing a weak spring 73, so that, upon displacement of the branch 5 toward the branch 48, the jaw 3 is displaced by a weak force toward the first jaw 11. A long lever 70 is pivotally mounted by a pivot mounting 15 to the tool body 10 near the clamping jaws 3, 11 and extends along the branch 48 to the area of the end thereof, where the lever 70 has a projecting shoulder 14, which can co-operate with the branch 5 when the same assumes a displacement position near the branch 48. A rack 13 may be coupled to the movable clamping jaw 3 by means of a locking mechanism 45. The locking mechanism may have the design shown in Fig. 1, the clamping jaw 3 being carried by a support 31 having a recess facing the rack 13 and receiving a slider 7, which by means of slide guides 20, 201 is dis- placeable toward and away from the rack 13, which extends parallel to the path of motion of the displacement (the slide guide 4) of the clamping jaw 3.

The slider 7 carries a rack 9. The racks 9 and 13 have toothings of saw-tooth shape facing each other, accordingly one flank of the teeth being substantially directed perpendicularly to the longitudinal direction of the racks.

The branch 5 is shown to have a bar 8 oriented in the displacement direction of the branch 5 and having a front chamfered surface 81, which is facing a complementary chamfered surface 21 on the side of the rack 9 facing away from the rack 13. When the branch 5 is displaced to a distance

from the branch 48, which depends on the size of the object, the chamfered surfaces 81, 21 engage each other and the rack 9 is displaced into engagement with the rack 13.

Upon continued bringing together of the branches 5, 48, the bar 8 can pass behind the rack 9 and lock the same into engagement with the rack 13. A retraction spring 161 is arranged to retract the slider 7 and thereby the rack 9 to the bottom area of the recess of the support 31 when the bar 8 is retracted toward the position shown in Fig. 1.

When the locking device 45 has locked the clamping jaw 3 to the rack 13 in respect of movement in the direction of the slide guide 4 and the rack 13, the rack 13 contacts the lever 70 by means of a supporting shoulder 16 at a small distance from the pivot mounting 15. The rack 13 is shown displaceably mounted on a slide guide 29 for displacement motion in the longitudinal direction thereof.

The rack 13 is shown displaced toward a normal position along the guide 29 by means of a weak spring 28.

Correspondingly, the lever 70 is shown to be biased by a weak spring 25 toward a starting end position. At a predetermined displacement position of the movable branch 5, this engages with and begins to actuate the lever 70, independently of the size of the object 12.

Immediately after the bar chamfer 81 has passed the chamfered surface 81 of the rack 9, the supporting shoulder 14 of the lever 70 is in the immediate vicinity of the side of the branch 5 facing thereto. A continued bringing together of the branches 5 and 48 then means that the lever 70 is turned counter-clockwise, and can by the gear ratio thereof (the distance of the supporting shoulders 16, 14 from the pivot mounting 15) displace, by the corresponding gear ratio, the jaw 3 toward the jaw 11, the object 12 being squeezed-in by a great force.

In Fig. 2, it can be seen that the slider 7 has grooves 20 on opposite sides, the grooves 20 receiving the appurtenant guiding rails 201 on the opposite side walls of the recess. Furthermore, in Fig. 2, it can be seen that the rack 9 abuts against the slider side that lies in the plane of Fig. 1. On this slider side 50, there is a groove 19 that extends parallel to the guide 4. On the side 51 of the rack 9 facing thereto, there is a projecting rail 191, the length of which is smaller than the length of the groove

19, but the height of which corresponds to the width of the groove 19. At each end of the rail 191, there is a spring 17 and 18, respectively, which rests against the short end walls of the groove 19 when the rack 9 and the slider 7 abut against each other via the side surfaces 50, 51. The rack 9 has, as viewed in Fig. 1, a width that is somewhat smaller than the width of the slider 7 (the width of the recess) . In this way, the rack 9 is afforded a limited mobility from a centred intermediate position in relation to the slider, in the longitudinal direction of the rack 13. This means that even if the teeth of the racks are relatively large, they can engage each other properly when the locking device 45 is locked, since the springs 17, 18 and the length difference between the groove 19 and the rail 191 affords a relative displacement between the racks 9, 13 corresponding to one tooth. In this way, a proper tooth engagement can be obtained between the racks 9, 13, independently of the size of the teeth, when the locking device locks. As soon as the branch 5 is detached, the branch 5 is displaced away from the branch 48 under the impact of the springs 71, 72, the bar being retracted, and the rack 9 being retracted by the spring 16 from the engagement with the rack 13, so that the jaw 3 can be displaced away from the jaw 11 and is ready for a new gripping operation. Since the transmission of the tool affords a high force ratio, the tool can, in principle, also be used

as a spanner, or as pliers, or as a shearing tool, if the jaws 3, 11 are provided with suitable edges and/or dies.

Fig. 4 shows a gripping tool that in many respects corre- sponds with the tool according to Fig. 1 in the structural and functional respect.

Therefore, the description of the object of Fig. 4 will be focused on the parts of the tool that differ from the cor- responding parts in the embodiment according to Fig. 1.

Thus, in Fig. 4 it can be seen that the handle branch 5, which is connected to the linearly guided shaft 8 carrying the wedge, has a first branch part 51 fixedly connected to the shaft 8, and a second branch part 52 that is connected to the first part 51 by a pivot joint 53 for turning toward and away from the fixed handle branch 48. A return spring 59 is arranged to turn the branch part 52 toward a turned- out turning end position (shown in Fig. 4) in the direction away from the first branch 48. In this turning end position, a ratchet 60, which is carried by the branch part 52 by means of a locking element 63, can engage an appurtenant groove 64 on the branch part 51. When the handle part 52 is turned around the hinge toward the branch 48, the distance between the point of attachment of the ratchet to the branch part 52 and the groove 64 increases so that the locking element comes loose from the groove 64 by an elas ^¬ tic deflection. The ratchet 60 has a shaft part, and a nose angled-out thereto, which, after having come loose from the groove 64, rests with the end thereof against the surface of the branch part 51, and is biased against the same, in order to again be able to snap into the groove 64 when the branch part 52 returns to the outer turning end position thereof .

At the hinge 53 thereof, the branch part 52 carries a short lever 54 substantially deflected 90° therefrom and gener-

ally directed toward the body 130 in order to, in the outer turning end position of the branch part 52, be able to engage under an edge of a pivotally mounted 55 slider 56, when the movable branch 5 has been displaced toward the fixed branch 48 and the clamping jaws have come into gripping engagement. Upon the turning of the branch part 52, the lever 54 will apply a force in the longitudinal direction of the shaft part 52 against the slider 56, which then, having a surface 58 that essentially is perpendicular to the surface 57 that contacts the lever 54, applies a force against the rack 13 in the longitudinal direction thereof. The rack 13 is guided by the guide rail 29 and is biased toward a displacement neutral position by a leaf spring 128 carried by the body 130.

By means of a leaf spring 59 carried by the body 130, the slider 56 is biased toward a turning neutral position shown in Fig. 4, in order to be in the correct rotary position for the co-operation with the lever 54 when the shaft part 52 is turned from the turning end position thereof.

In Fig. 4, it can also be seen that the body 130 carries a linear guide 140 for the shaft 8. Furthermore, it can be seen that the body 7 received and guided in the recess 202 on the underside thereof is provided with the serration that comes into engagement with the tooth bar 13, and that the wedge 9' co-operating with the wedge 81 is fixedly connected to the body 7, which is supported in the displacement direction of the wedge 81 by the walls of the recess 202.

Thus, the pivotally mounted lever, which is formed by the branch part 52 and the lever arm 54 thereof, affords a high force ratio for the displacement of the rack 13. When dis- placing the branch 5 via the branch part 52, the ratchet 60 will initially hold the branch part 52 in the end position thereof shown in Fig. 4, until the lever 54 comes into

engagement position in relation to the slider 56. A continued increased displacement force against the branch part 52 entails that the lock 60 comes loose, the lever 54 turning the slider 56 around the mounting thereof, whereby the rack 13 being displaced by a great force for displacement of the movable clamping jaw toward the fixed clamping jaw. By means of the force-changing transmission including the branch part 52 made as a pivotally mounted double lever, and the pivotally mounted slider/link 54, the space requirement for the force-changing mechanism is reduced and the same gets a robust and simple structure. Furthermore, the manual force application can be carried out in a smooth and easy way.