Pneumatically operable work tool

Abstract

A pneumatically operable work tool for use in body construction in the motor vehicle industry includes a cylinder which has a cylinder housing, a piston moveable therein and a piston rod, which is connected to said piston, moveable linearly and guided out of the cylinder housing, and with a head housing connected to the cylinder housing, wherein a region of the piston rod protruding into the head housing cooperates with at least one toggle lever to pivot an arm assigned to the toggle lever, in particular a gripper arm or clamping arm, wherein this arm is mounted in the head housing and is pivotable between a closed position and an opened position. In the region of its end protruding into the head housing, the piston rod receives a bearing element for the toggle lever, wherein the bearing element is guided in a guide of the head housing in the direction of the longitudinal axis of the piston rod, and the bearing element, at a radial distance from the longitudinal axis of the piston rod, has a receiver for pivotable mounting of a hinge connector, which in the region of an end facing away from the bearing element is connected pivotably to the arm at a distance from a pivot axis of the arm, wherein the end pivot axes of the hinge connector and the pivot axis of the arm are arranged parallel to each other.

Claims

1. A pneumatically operable work tool, with a cylinder which has a cylinder housing, a piston moveable therein and a piston rod which is connected to said piston, moveable linearly and guided out of the cylinder housing, and with a head housing connected to the cylinder housing, wherein a region of the piston rod protruding into the head housing cooperates with at least one toggle lever to pivot an arm assigned to the toggle lever, wherein the arm is mounted in the head housing and is pivotable between a closed position and an opened position, wherein in the region of an end of the piston rod protruding into the head housing, the piston rod receives a bearing element for the toggle lever, wherein the bearing element is guided in a guide of the head housing in the direction of a longitudinal axis of the piston rod, and the bearing element, at a radial distance from the longitudinal axis of the piston rod, has a receiver for pivotable mounting of a hinge connector, which in the region of an end of the hinge connector facing away from the bearing element is connected pivotably to the arm at a distance from a pivot axis of the arm, wherein a pair of end pivot axes of the hinge connector and the pivot axis of the arm are arranged parallel to each other, wherein a base of the cylinder housing facing away from the head housing has a tappet configured for engaging a facing end of the piston rod and for rotation of the piston rod in the closed position of the arm when the piston is arranged in the region of the base.

2. The work tool as claimed in claim 1, wherein a single toggle lever is provided for pivoting an assigned arm, or two toggle levers are provided for pivoting an assigned arm and each of the toggle levers serves to pivot a respective arm.

3. The work tool as claimed in claim 2, wherein the bearing element has two recesses for pivotable mounting of two hinge connectors, wherein the two hinge connectors, in the region of the ends of the hinge connectors facing away from the bearing element, are connected pivotably to the two arms at a distance from the pivot axes of the arms, and wherein the pivot axes of the hinge connectors and the pivot axes of the arms are arranged parallel to each other.

4. The work tool as claimed in claim 3, wherein the bearing element, the hinge connectors and the arms are arranged symmetrically to a plane running through the longitudinal axis of the piston rod.

5. The work tool as claimed in claim 3, wherein the respective receiver has a plate-like shoulder connected to a base body of the bearing element, and wherein the shoulder has a hole for receiving a bearing bolt for engagement with the respective hinge connector.

6. The work tool as claimed in claim 1, wherein in the axial direction of the piston rod, the bearing element has bearing parts arranged behind each other and spaced apart for mounting the bearing element in the head housing, and wherein at least one receiver is arranged between the bearing parts in relation to the axial direction of the piston rod.

7. The work tool as claimed in claim 1, wherein the bearing element is mounted in the guide of the head housing by means of a plain bearing or a roller bearing.

8. The work tool as claimed in claim 1, wherein the guide has parallel guide faces which are arranged parallel to the pivot axis of the arm.

9. The work tool as claimed in claim 1, wherein the tappet is configured for axially displacing the piston rod in the closed position of the arm when the piston is arranged in the region of the base, in order to move the toggle lever out of an over-dead-center position.

10. A pneumatically operable work tool, with a cylinder which has a cylinder housing, a piston moveable therein and a piston rod which is connected to said piston, moveable linearly and guided out of the cylinder housing, and with a head housing connected to the cylinder housing, wherein a region of the piston rod protruding into the head housing cooperates with at least one toggle lever to pivot an arm assigned to the toggle lever, wherein the arm is mounted in the head housing and is pivotable between a closed position and an opened position, wherein in the region of an end of the piston rod protruding into the head housing, the piston rod receives a bearing element for the toggle lever, wherein the bearing element is guided in a guide of the head housing in the direction of a longitudinal axis of the piston rod, and the bearing element, at a radial distance from the longitudinal axis of the piston rod, has a receiver for pivotable mounting of a hinge connector, which in the region of an end of the hinge connector facing away from the bearing element is connected pivotably to the arm at a distance from a pivot axis of the arm, wherein a pair of end pivot axes of the hinge connector and the pivot axis of the arm are arranged parallel to each other, wherein the piston rod is not variable in length and the opened position of the arm is adjustable, wherein the piston rod has a threaded portion and in the region of the threaded portion receives a buffer part which is adjustable in the direction of the longitudinal axis of the piston rod and, in the opened position of the arm, lies on a support face that is stationary relative to the head housing, wherein a tappet engages a facing end of the piston rod such that the piston rod is rotatable relative to the longitudinal axis, and wherein the piston rod is rotatable relative to the bearing element.

11. The work tool as claimed in claim 10, wherein the buffer part is positioned rotationally fixedly in the head housing.

12. The work tool as claimed in claim 10, wherein the stationary support face is formed as a support face of the head housing.

13. The work tool as claimed in claim 10, wherein in the closed position of the arm, the toggle lever is arranged in an over-dead-center position.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) The accompanying drawing figures depict the present invention with reference to exemplary embodiments, without being restricted thereto and/or limited thereby.

(2) FIG. 1 shows a first exemplary embodiment of a pneumatically operable work tool which has a single arm, illustrated in a section view in a set opened position of 30.

(3) FIG. 2 shows the work tool according to FIG. 1 in an opened intermediate position.

(4) FIG. 3 shows the work tool according to FIGS. 1 and 2 in the closed position.

(5) FIG. 4 shows the first exemplary embodiment of the work tool in a section through a piston rod axis of the work tool, perpendicular to the section view in FIGS. 1 to 3, illustrating a modified set opened position.

(6) FIG. 5 shows the first exemplary embodiment of the work tool illustrating a set opened position of 50.

(7) FIG. 6 shows the work tool according to FIG. 5 in an intermediate opened position.

(8) FIG. 7 shows the work tool according to FIGS. 5 and 6 in the closed position.

(9) FIG. 8 shows a second exemplary embodiment of a pneumatically operable work tool which has two arms, illustrated in a section view at a set opened position of 90.

(10) FIG. 9 shows the work tool according to FIG. 8 in an intermediate opened position.

(11) FIG. 10 shows the work tool according to FIGS. 8 and 9 in the closed position.

(12) FIG. 11 shows the second exemplary embodiment of the work tool illustrating the set opened position of 160.

(13) FIG. 12 shows the work tool according to FIG. 11 in an intermediate opened position.

(14) FIG. 13 shows the work tool according to FIGS. 11 and 12 in the closed position.

(15) FIG. 14 shows an enlarged section view through the base region of the cylinder when the tappet is not in the active position.

(16) FIG. 15 shows a section view according to FIG. 14 with the tappet in the active position.

(17) FIG. 16 shows an enlarged section view of the connection of the bearing element to an arm.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

(18) The drawing figures show a pneumatically operable work tool 1 which is in particular used in body construction in the motor vehicle industry. The work tool 1 as a handling gripper is fitted with a single arm 2 (gripper arm) according to the exemplary embodiment in FIGS. 1 to 7, or with two arms 2 (two gripper arms) according to the exemplary embodiment in FIGS. 7 to 13. Both embodiments have a similar structure. To this extent, initially the first exemplary embodiment will be described with reference to the depiction in FIGS. 1 to 4.

(19) According to the view in FIGS. 1 to 4, the work tool 1 has a cylinder 3. A head housing 5 is connected to a cylinder housing 4 via fixing means (not shown). The cylinder housing 4 receives a piston 6 displaceable therein, and a piston rod 7 which is connected to said piston, is moveable linearly and guided tightly outside the cylinder housing 4, and is not variable in length. A region of the piston rod 7 protruding into the head housing 5 cooperates with at least one toggle lever 8 for pivoting its assigned arm 2. This arm 2 is mounted in the head housing 5 via an axis 9 and can pivot about this axis 9 between an opened position (FIG. 1) and a closed position (FIG. 3).

(20) The opened position of the arm 2 is fully adjustable. For this, the piston rod 7 has a threaded portion 10 and in the region of this receives a buffer part 11 which is adjustable in the length direction of the piston rod 7. In the opened position of the arm 2, the buffer part 11 lies against a support which is stationary relative to the cylinder housing 4 and formed as an annular support surface 12 of the head housing 5, surrounds the piston rod 7 and is arranged orthogonally to the longitudinal axis 13 of the piston rod 7. The support surface of the buffer part 11, carrying reference numeral 14, is also annular and cooperates with the support surface 12 of the head housing 5. This support surface 14 is arranged parallel to the support surface 12.

(21) The buffer part 11 is positioned rotationally fixedly in the head housing 5, in concrete terms via a groove (not shown) which extends parallel to the longitudinal axis 13 of the piston rod 7 and in which the buffer part 11 engages. The thread in the region of the threaded portion 10 between the piston rod 7 and the buffer part 11 is self-locking.

(22) The piston rod 7 is rotatable relative to its longitudinal axis 13 and, in the region of its end facing the toggle lever 8, receives a bearing element 15 for the toggle lever 8. The piston rod 7 is rotatable about the longitudinal axis 13 relative to the bearing element 15. For this, the piston rod 7 is inserted in a receiver 16 of the bearing element 15 and connected fixedly to the bearing element 15 by means of a form-fit ring 17 in the extension of the longitudinal axis 13.

(23) This connection allows rotation of the piston rod 7 about the longitudinal axis 13 relative to the receiver 16 and hence to the bearing element 15.

(24) A base 18 of the cylinder housing 4 facing away from the head housing 5 has means 19 for turning the piston rod 7 into the closed position (FIG. 3) of the arm 2 when the piston 6 is arranged in the region of the base 18. The means 19 is a tappet which is mounted tightly in the base 18 and is displaceable in the direction of the longitudinal axis 13 of the piston rod 7. The end of the tappet 19 arranged outside the cylinder housing 4 has a hexagonal recess 20 to receive a tool (not shown) for turning the tappet 19 about the longitudinal axis 13, wherein the tool is inserted with a hexagonal end in the hexagonal recess 20. The end arranged inside the cylinder housing 4 has a protrusion 21 with a hexagonal cross section. These details are shown in the view in FIG. 14 with the tappet 19 not engaged. FIG. 15 shows the engagement of the tappet 19, wherein in the closed position of the arm 2, the protrusion 21 is inserted in a recess 22 of hexagonal cross section in the facing end of the piston rod 7. By twisting the tappet 19 using the tool, the piston rod 7 can be turned and consequently the position of the buffer part 11 relative to the piston rod 7 changed. FIG. 15 illustrates that, when the piston rod 7 is in the end position close to the base and the tappet 19 is inserted in the recess 22, an axial gap 23 remains between a head 24 of the tappet 19 and the base 18, so that on application of an external force or impact force on the tappet 19 in the region of its head 24, the tappet 19 is displaced axially, leading to a mechanically induced, axial displacement of the piston rod 7 slightly away from the base 18.

(25) The bearing element 15 is formed symmetrical relative to a plane running through the longitudinal axis 13 of the piston rod 7. Two shafts 25 are mounted in the bearing element 15, wherein the respective shaft 25 receives roller-like bearing elements 26 on both sides of the bearing element 15, which are guided in a bearing groove 27 extending in the direction of the longitudinal axis 13. As shown in FIG. 2, the bearing groove 27 has parallel guide faces 27A which are arranged parallel to the pivot axis 9 of the arm 2. Thus the bearing element 15 is guided substantially play-free in the direction of the longitudinal axis 13. On its sides facing away from each other, the bearing element 15 has plate-like receivers 28 in the form of tabs which are connected to a base body 39 of the bearing element 15. Each receiver 28 is designed to receive a plate-like hinge connector 29 in the region of an axis 30. In the embodiment which has only one arm 2, only one receiver 28 is engaged, while the other receiver 28 remains free. This other receiver 28 is only engaged in the case where a second arm 2 is provided.

(26) In the axial direction 13 of the piston rod 7, the bearing element 15 has roller bearing elements 26 arranged behind each other and spaced apart for mounting the bearing element 15 in the head housing 5. The receiver 28 or the two receivers 28 are arranged between these roller bearing elements 26 relative to the axial direction 13 of the piston rod 7.

(27) In the region of its end facing away from the bearing element 15, the hinge connector 29 is connected pivotably to the arm 2 in the region of an axis 31. This axis 31 is positioned spaced from the axis 9 of the arm 2. The axis 9 and the axes 30 and 31 are arranged parallel to each other. The axes 9, 30 and 31 are constructed such that axes 30 and 31, and 9 and 31, form the toggle levers 8, wherein in the opened position of the arm 2 according to FIG. 1, the connecting line between the axes 30 and 31 forms an angle of less than 90 relative to the connecting line of axes 9 and 31, in relation to their center point, whereas in the closed position of the arm 2 according to FIG. 3, this angle is slightly greater than 90 so that a slight over-dead-center position results in which the bearing element 15 is fixed in the direction of the longitudinal axis 13 and in the direction of the piston rod 7, wherein the roller bearing elements 26 on the piston rod side, in the region of the end of the bearing groove 27 facing the piston rod, lie at the end 32 of the bearing groove 27.

(28) FIG. 16 shows the detail of the mounting of the hinge connector 29 in the arm 2. Here the axis 31 is extended and engages in a guide groove 33 of the head housing 5 extending substantially over a quarter circle.

(29) The function of the work tool 1 according to the exemplary embodiment shown in FIGS. 1 to 4 is as follows:

(30) The cylinder housing 4 is divided by the piston 5 into two working chambers 34 and 35 of the fluid. Starting from an opened position of the arm 2 at 30 relative to the longitudinal axis 13, in which the arm 2 is in the maximum opened position relative to the set position of the buffer part 11, in the known manner the working chamber 34 is pressurized with fluid so that the piston 6 is moved in the direction of the base 18. Here the buffer part 11 in the region of its support surface 14 comes out of contact with the support surface 12 of the head housing 5. The piston 6 and the piston rod 7 draw the bearing element 15 with them and via the toggle lever 8, the arm 2 moves with its gripper element 36 arranged in the region of the free end of the arm 2 in the direction of a gripper element 37 mounted in the head housing 5. The intermediate position is shown in FIG. 2.

(31) On further movement of the piston 6, this finally reaches its end position close to the base 18 in which the two gripper elements 36 and 37 make contact and a metal sheet arranged between them is gripped by the gripper elements 36 and 37. When the arm 2 is closed, the toggle lever 8 is in a slightly over-dead-center position in which the connecting line of the two axes 30 and 31, relative to their center point, is arranged at an angle of slightly not equal to 90 to the longitudinal axis 13 of the piston rod 7, such that the center point of the axis 30 is arranged slightly closer to the base 18 than the center point of the other axis 31. Since a stop position is also formed in this closed position of the arm 2, in which the roller bearing elements 26 on the piston rod side lie at the end 32 of the guide groove 33, the toggle lever 8 can only be moved out of this over-dead-center position by active pressurization of the other working chamber 35, into the fully opened position according to FIG. 1 when the buffer part 11 is supported on the head housing 5.

(32) If the fluid supply to the work tool 1, in particular to the working chamber 35, has failed, this over-dead-center position of the toggle lever 8 can only be released by the previously described mechanical action on the tappet 19. Here, via the axial displacement of the piston rod 7 and hence the corresponding axial displacement of the bearing element 15, the hinge connector 29 is pivoted slightly so that the center point of the axis 30 is further away from the base 18 than the center point of the axis 31. In this position, a pivoting of the arm 2 is mechanically possible when the arm 2 is held.

(33) As explained above in relation to the depiction of FIGS. 14 and 15 in particular, the position of the buffer part 11 can be changed by turning the piston rod 7. The tappet 19 is inserted in the recess 22 of the piston rod 7. On pressurization of the cylinder 3 to transfer the piston 6 from the closed position of the work tool, the tappet 19 is moved back, wherein pressure medium is supplied to the working chamber 35 and also acts on the facing end of the tappet 19. On mechanical actuation of the tappet 19 to transfer the toggle lever 8 from the over-dead-center position, the subsequent return movement of the tappet 19 also takes place because of the pressure medium supplied to the working chamber 35 (after the pressure medium has been made available again).

(34) In FIG. 4, reference numeral 38 designates a sampling device which is mounted in the head housing 5 and serves to sample the position of the bearing element 15 or buffer part 11.

(35) FIGS. 5 to 7 show the operating states described above for FIGS. 1 to 4 for a work tool 1 with a changed opening angle, with an opening angle of 50. This position clearly results for example because, with the arm 2 closed, the support surface 12 and the support surface 14 have a different distance from each other, wherein the change of distance corresponds to the change in position of the buffer part 11 relative to the piston rod 7.

(36) The exemplary embodiment in FIGS. 8 to 13 largely corresponds to that of FIGS. 1 to 7. To avoid repetition, reference is made to the detailed description of the first exemplary embodiment.

(37) In the exemplary embodiment according to FIGS. 8 to 13, instead of one arm 2, two arms 2 are provided. The second arm is connected in the same way as the first arm according to the first exemplary embodiment, wherein the bearing element 15, hinge connectors 29 and arms 2 are arranged symmetrically to the plane running through the longitudinal axis 13 of the piston rod 7. To this extent, reference is made to the description above concerning the connection of the one arm 2.

(38) The second exemplary embodiment differs from the first exemplary embodiment in that the respective arm 2 is modified and, in addition, the gripper element 37 is part of the second arm 2.

(39) FIG. 8 shows the work tool 1 with the two arms 2 in an opened position of 90, FIG. 9 shows the intermediate position and FIG. 10 the closed position, in which the two gripper elements 36 and 37 make contact with each other.

(40) For the design of the work tool 1 with two arms 2, FIG. 11 shows a different position of the buffer part 11, giving an opened position of 160 according to FIG. 11, FIG. 12 shows the intermediate position and FIG. 13 the closed position.

(41) The two exemplary embodiments illustrate that, by simple conversion or supplementing of the work tool 1, this can be converted to the variant with one arm 2 or two arms 2. It is merely necessary, starting from the variant with one arm 2, to use a modified head housing 5 which has no receiver for the gripper element 37 and instead, in a modified head housing 5, mount the two arms 2 via the toggle lever 8 and connect them to the bearing element 15.