PINCER TOOL WITH ASYMMETRICAL WEDGE

Abstract

A pincer tool (10) for tightening a band clamp. The pincer tool (10) includes a pincer head (12) including a base element (14), two jaw elements (16a, 16b) pivotably attached to the base element (14), wherein the jaw elements (16a, 16b) each include a jaw end (20a, 20b) and a rear end (22a, 22b) on opposite sides of the pivot point, and a wedge element (26) mounted on the base element (14) to be movable in a longitudinal direction (D) by pressure of a pressurizing agent, wherein the wedge element (26) is configured to separate the rear ends (22a, 22b) of the jaw elements (16a, 16b) when being pressed in the longitudinal direction (D) so as to move each of the jaw ends (20a, 20b) by a stroke.

Claims

1. A pincer tool (10) for tightening a band clamp, the pincer tool (10) including a pincer head (12), the pincer head (12) comprising: a. a base element (14); b. two jaw elements (16a, 16b) pivotably attached to the base element (14) on a pivot point, wherein the jaw ele-ments (16a, 16b) each include a jaw end (20a, 20b) and a rear end (22a, 22b) on opposite sides of the pivot point; and c. a wedge element (26) mounted on the base element (14) so as to be movable in a longitudinal direction (D) by pressure of a pressurizing agent, wherein the wedge element (26) is configured to separate the rear ends (22a, 22b) of the jaw elements (16a, 16b) when being pressed in the longitudinal direction (D) so as to move each of the jaw ends (20a, 20b) by a stroke, wherein the wedge element (26) has at least one configuration in which the strokes by which the jaw ends (20a, 20b) are moved differ from each other.

2. The pincer tool (10) according to claim 1, wherein the wedge element (26) includes wedge surfaces (26a, 26b) with different slopes.

3. The pincer tool (10) according to claim 1, wherein the wedge element (26) includes a rear element (30) guided in the longitudinal direction (D) and a front element (28) configured to be pivoted by a difference in counterforces exerted by the rear ends (22a, 22b).

4. The pincer tool (10) according claim 3, wherein the rear element (30) and the front element (28) include opposing abutment surfaces (30a, 30b, 28a, 28b) configured to stop the pivoting at predetermined maximum pivot angles.

5. The pincer tool (10) according claim 4, wherein the opposing abutment surfaces (30a, 30b, 28a, 28b) are curved and shaped in such a manner that a contact area be-tween the rear element (30) and the front element (28) in-creases with increasing difference in counter-forces.

6. The pincer tool (10) according to claim 3, wherein the front element (28) includes a main body (32 and joint head (34) engaging in a socket structure (36) of the rear element (30, wherein the joint head (34) is connected to the main body by a neck part (38.

7. The pincer tool (10) according to claim 1, wherein the rear ends (22a, 22b) of the jaw elements (16a, 16b) are provided with rolls (161a, 161b).

Description

[0019] The figures illustrate the following:

[0020] FIG. 1 illustrates a pincer tool according to a first embodiment of the invention; and

[0021] FIG. 2 illustrates a pincer tool according to a second embodiment of the invention.

[0022] FIG. 1 shows pincer tool 10 according to a first embodiment of the invention. The pincer tool 10 is configured for tightening a band clamp, in particular a band clamp with overlapping inner- and outer band portions which are moved relative to one another when the band clamp is being closed. This includes but is not limited to low-profile clamps with engagement hooks or engaging the jaws of the pincer tool 10 and so-called stepless ear clamps.

[0023] The pincer tool 10 includes a main body (not illustrated) with one or more pistons to be moved by the pressure of a pressurizing agent. The pressurizing agent may by air in the case of a pneumatic pincer tool 10 or hydraulic oil in the case of a hydraulic pincer tool 10.

[0024] A pincer head 12 is attached to a front end of the main body. The pincer head 12 includes a plate-shaped base element 14 and two jaw elements 16a, 16b pivotably attached to the base element 14 via a pivot bolt 18a, 18b on a pivot point, respectively.

[0025] The jaw elements 16a, 16b each include a jaw end 20a, 20b and a rear end 22a, 22b on opposite sides of the pivot point such that the jaw ends 20a, 20b are approached to each other when the rear ends 22a, 22b are separated and vice versa. The pivot axis of the jaw elements 16a, 16b as defined by the pivot bolts 18a, 18b is oriented in a direction perpendicular to the longitudinal direction. A spiral spring 24 is arranged between the jaw elements 16a, 16b and configured to restore the jaw elements 16a, 16b into an open configuration when no force is exerted to the rear ends 22a, 22b.

[0026] The pincer head 12 further includes a wedge element 26 mounted on the base element 14 so as to be movable in a longitudinal direction D by pneumatic pressure. The wedge element 26 is directly or indirectly connected to the foremost piston in the main body or be formed as one piece with the piston. The wedge element 26 is configured to separate the rear ends 22a, 22b of the jaw elements 16a, 16b when being pressed in the longitudinal direction D so as to move each of the jaw ends 20a, 20b by a stroke along a curved path around the pivot point, wherein the path is oriented in a direction substantially perpendicular to the longitudinal direction D and perpendicular to the pivot axis.

[0027] According to the embodiment of FIG. 1, the wedge element 26 includes wedge surfaces 26a, 26b with different slopes in relation to the longitudinal direction D. The rear ends 22a, 22b of the jaw elements 16a, 16b are provided with rolls 161a, 161b in contact with the opposing wedge surfaces 26a, 26b such that the slopes of the wedge surfaces 26a, 26b set the gear ratio of the translation of the longitudinal movement of the wedge element 26 into the transversal movement of the jaw ends 20a, 20b of the jaw elements 16a, 16b. The wedge element 26 is asymmetrical with regard to the longitudinal direction D.

[0028] As a consequence of the different slopes, the wedge element 26 has a configuration which is such that the strokes by which the jaw ends 20a, 20b are moved by a full or predetermined stroke of the wedge element 26 differ from each other.

[0029] FIG. 2 shows a second embodiment of the invention. In order to avoid repetition, the following description of the second embodiment is essentially limited to differences from the first embodiment of the invention. Because of the unchanged features, the skilled person is referred to the description of the first embodiment. The same reference signs are used for features of the second embodiment that have the same or similar effect in order to emphasize the similarities.

[0030] In the second embodiment of FIG. 2, the wedge element 26 includes a rear element 30 guided in the longitudinal direction D and a flexible, pivotable front element 28 configured to be pivoted by a difference in counterforces exerted by the rear ends 22a, 22b. In the forceless configuration of FIG. 2, the wedge surfaces 26a, 26b of the front element 28 have opposing slopes with the same absolute value in relation to the longitudinal direction D such that, in the forceless configuration, the wedge element 26 is symmetrical with regard to the longitudinal direction D.

[0031] When a difference in counterforces exerted by the rear ends 22a, 22b of the jaw elements 16a, 16b exists, the an angular momentum acts on the front element 28 and the front element 28 is pivoted around a pivot axis perpendicular to the longitudinal direction D by a certain amount.

[0032] The rear element 30 and the front element 28 include opposing abutment surfaces 30a, 30b, 28a, 28b configured to stop the pivoting at predetermined maximum pivot angles. The opposing abutment surfaces 30a, 30b, 28a, 28b are curved and shaped in such a manner that a contact area between the rear element 30 and the front element 28 increases with increasing difference in counterforces. When large forces are applied, the abutment surfaces 30a, 30b, 28a, 28b will almost inevitably be in full contact such that the pressure is transmitted via the entire abutment surfaces 30a, 30b, 28a, 28b rather than the pivot joint between the rear element 30 and the front element 28.

[0033] More specifically, the front element 28 includes a main body 32 and a joint head 34 engaging in a socket structure 36 of the rear element 30, wherein the joint head is connected to the main body by a neck part 38.

[0034] When a difference in transversal counterforces is applied to the jaw ends 20a, 20b of the jaw elements 16a, 16b, a difference proportional to the former difference exists between the forces applied by the rolls 161a, 161b onto the wedge surfaces 26a, 26b. The resultant force pivots the front element 28 into one of the two opposite directions and moves the wedge element 26 into an asymmetrical configuration in which the slopes of the wedge surfaces 26a, 26b as measured with reference to the longitudinal direction D differ from each other. This applies in particular to a configuration where two of the opposing pairs of abutment surfaces 30a, 30b, 28a, 28b are in contact. As a consequence, the wedge element 26 has a configuration which is such that the strokes by which the jaw ends 20a, 20b are moved by a full or predetermined stroke of the wedge element 26 differ from each other as in the embodiment of FIG. 1.

[0035] Tests showed a better result compared to a standard wedge. A higher closing force could be reached before hook breaking.

LIST OF REFERENCE NUMBERS

[0036] 10 pincer tool [0037] 12 pincer head [0038] 14 base element [0039] 16a, 16b jaw elements [0040] 18a, 18b pivot bolts [0041] 20a, 20b jaw ends [0042] 22a, 22b rear ends [0043] 24 spiral spring [0044] 26 wedge element [0045] 26a, 26b wedge surface [0046] 28 front element [0047] 28a, 28b abutment surfaces [0048] 30 rear element [0049] 30a, 30b abutment surfaces [0050] 32 main body [0051] 34 joint head [0052] 36 socket structure [0053] 38 neck part [0054] 161a, 161b rolls