A gripping tool with displaceable jaws

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

An object of the invention is to provide a gripping tool, which initially, upon manual operation with a small force, offers a quick distance decrease between the parallel clamping jaws of the tool, for gripping the object in ques- tion, and which then, as a continuation of the manual operation by a relatively small driving force, offers a pressing of the clamping jaws by a great force against the object .

The object is attained by the invention.

The invention is defined in the appended independent claim 1.

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 a side view of an embodiment example of a gripping tool according to the invention .

Fig. 2 schematically shows a section taken along the line H-II in Fig. 1.

Fig. 3 schematically shows a section taken along the line

IH-III in Fig. 1.

Fig. 4 shows in a broken-away perspective view, another embodiment of the mounting of the second handle branch in the frame of the gripping tool.

Fig. 5 schematically shows a side view of another gripping tool .

Fig. 1 shows a gripping tool that comprises a frame 30, comprising a first fixed clamping jaw 31, and a first fixed handle branch 32, which extend perpendicularly to the clamping surface of the first clamping jaw. The first handle branch 32 is provided with a slide guide 33 projecting perpendicularly thereto for a slider 6. The slider 6 carries a lever 4 via a pivot mounting 3. The lever 4 has a first part 41 that forms a second handle branch of the tool. A second clamping jaw 2, which is parallel to the first clamping jaw 31, is arranged guided along the frame 3 for movement to and away from the fixed clamping jaw 31. On the frame 31, a body 21 is turnably mounted via a pivot mounting 22. A transmission bar 51 is coupled between a pivot mounting 24 on the body 21 and the pivot mounting 3 of the lever 4 on the slider 6. The mounting 24 is shown displaced in the longitudinal direction of the branch 32 from the pivot mounting 22, in the direction away from the clamping jaw 31. A transmission bar 27 is connected to the movable clamping jaw 2 and extends in the longitudinal direction of the branch 32, and is turnably connected by a pivot mounting 23 to the body 21. The pivot mounting 23 is situated at a distance from the pivot mounting 22, and on the other side of the pivot mounting 22 from the guide 7. The transmission bar 27 contains a spring assembly 10, which gives the bar 27 a variable length. At the outer end portion of the guide 7, a spring 9 is shown, which pulls the lever 4 in the displacement direction of the slider 6 away from the body 21 toward an end position. As an alter ^¬ native, the spring 9 may be arranged to act between the clamping jaw 2 and the frame 30 in the longitudinal direc-

tion of the branch 32. At the nose thereof, the second part 42 of the lever, which is on the other side of the pivot mounting 3 in respect of the branch 41, carries a rack piece 61, which is shown pivotally mounted to the lever part 42. The lever part 61 is directed toward and generally parallel to an associated second rack part 62, which is arranged on a part of the second clamping jaw 2. Furthermore, there is seen that a tension spring 8 is coupled between the slider 6 and the branch part 41 of the lever, at a distance from the pivot mounting 3. Furthermore, there is an arresting mechanism 5 coupled between the branch part 41 of the lever and the slider 6. The arresting mechanism offers a pivot anchoring of the lever 4 up to a torque of a predetermined level around the pivot mounting 3 of the lever on the slider 6.

The tool functions in the following way. An operator grips with his/her hand over the handle branches 32 and 41. Initially, the branch 41 experiences a parallel displacement toward the branch 32, the slider 6 being conveyed against the action of the tension spring 9, which aims to bring back the slider 6 toward an outer end position in the slide guide 7. During the parallel displacement of the branch 41, the branch's displacement movement and thereby the slider's 6 displacement movement of the transmission bar 51 is transferred to the body 21, which thereby turns around the pivot mounting 22, the transmission bar 27 being displaced upward in Fig. 1 during the conveying of the movable clamp ^¬ ing jaw 2 toward an object inserted between the clamping jaws 2, 31. When the clamping jaw 2 is braked by the contact with the object 70, a continued parallel displacement movement of the branch 41 can be accommodated by the com ^¬ pression of the springs members 10 of the transmission bar 27, all the way until the rack element 61 comes into engagement with the rack 52. Upon a continued force action by the movable branch 41, subsequently the bias force of the tension spring 8 and finally the limit load of the dis-

engagable arrester 5 are overcome, after which the lever 4 begins to turn around the pivot mounting 3 of the slider 6. The distance between the pivot mounting and the tooth element 61 is considerable smaller than the distance between the pivot mounting and the contact area of the movable handle branch 41 with the hand of the operator, and therefore the applied torque around the pivot mounting 3 will result in a great upwardly directed displacement force of the movable clamping jaw 2 toward the object 70 and the fixed clamping jaw 31. Possible movements of the first transmission 51, 21, 27, 10 are accommodated by the spring 10.

The force ratio of the second transmission, established by the lever ratio of the lever 4, may be made so high that the object 70 in practice is locked in between the jaws 31, 2 by means of the force that manually can be applied over the branches 32, 41.

For releasing the object 70, the operation is performed in the opposite direction, i.e., the branch 41 is unloaded, whereby the same turns back around the pivot mounting 3 under the impact of the tension spring 8, so that the arresting mechanism 5 is brought back into an arrested state, the springs 9 and 10 being unloaded and bringing back the slider 6 to an outer end position in the guide 7, the first transmission bringing away the movable clamping jaw 2 from the fixed clamping jaw 31 in a relatively quick movement .

Fig. 2 illustrates that the movable clamping jaw 2 has a pair of branches 25 straddling the frame 30. Furthermore, it is seen in Fig. 2 that the frame 30 has an undercut groove 36, which receives a correspondingly formed protrusion 28 on the movable clamping jaw 2.

From Fig. 3, it can be understood that the guide 7 offers a stable linear guiding of the slider 6 and that the slider 6

has a laterally placed recess in which the lever arm 51 of the transmission is received for turning motion.

The tooth segment 61 could, per se, be replaced by a single tooth that engages the row of teeth 62, but it is preferred to allow the first tooth element 61 to have a plurality of teeth and be in the shape of a bar, which is turnably mounted at the end of the lever by means of a pivot mounting 62', so that the force transfer per tooth is reduced and so that the tooth element can be held in parallel engagement with the toothing 62 during the turning motion of the lever.

The co-operating teeth of the toothing 62 and the tooth element 61, respectively, are shown to have a saw-tooth shape in order to prevent the appearance of forces that tend to displace the tooth element 61 and thereby the slider 6 in the direction away from the toothing 62 upon the application of great clamping force along the toothing 62.

From Fig. 1, it can be understood that the arresting mechanism 5, in a known manner per se, comprises two co-operating wedge elements carried by the movable handle branch and the slider respectively, at a distance from the second handle branch pivot mounting 3 on the slider. One of the wedge elements is arranged displaceably out of the engagement with the other wedge element against the action of biasing members for releasing the arrester. Said biasing members may be made up by at least one of the wedge elements being resiliently elastically carried by a resilient bar. Furthermore, it is shown that the biasing members 8 aim to bring back the handle branch 41 to the end position in which the wedge elements are brought into arresting engagement.

Fig. 4 shows that the handle branch 4 carries an out of round journal 3', which is received in a rotationally locked way for displacement along the first longitudinal section 74 of the slide guide 7 up to the displacement end position, where the tooth element 61 comes into engagement with the rack 62 and where the slide guide 7 has a widened section 75 in which the journal 3' can rotate so that the second transmission 4, 42, 61, 62 can be activated.

Fig. 5 shows another embodiment, in which the branch 4 has a lug 3" that is received rotationally rigidly in the guide 7. The front end 42 of the branch 4 is rounded and meets a free end of a long shank part 81 of a lever, which is mounted on the branch 32 by the mounting 83. The long branch 82 of the lever carries one end of a bar 85, which at the other end carries tooth segment 61. The bar 85 is turnably movable in the plane of Fig. 5, between a stopper 68 and the cogging 62.

The bar 85 is biased by a leaf spring 91 against the stopper 68. The long branch 81 of the lever is biased by a leaf spring 92 against the front end 42 of the branch 4 in the plane of Fig. 5. The branch 4 is shown carrying a spring 97, which is directed in the linear displacement direction of the branch 4 and which preferably carries a stopper shoulder 96 on the end thereof turned toward the arm 85, which contacts the arm 85 when the branch has been dis ^¬ placed so far that the jaws of the pliers have gripped an object. In this way, the arm 85 is turned against the action of the spring 91 so that the tooth segment 61 engages the cogging 62, whereby the second transmission 80 is engaged.