DE20309300U1 - Parallel clamp for sheet metal presentation to laser welding unit has jaws retaining parallel presentation in both open and closed positions - Google Patents

Abstract

A grip has parallel jaws which are brought together to hold pieces of sheet metal at readiness e.g. for a laser welding process. The clamp head is esp. slides and/or at right angles to the clamp head centreline. The clamp head slides axially relative to the surrounding housing. The jaws retain their parallel presentation in both the open and closed positions.

Description

Edward Baumgartner
Pneumatics GmbH
Diesel Street 15

63579 Freigericht

Description

Parallel clamp

The invention relates to a parallel clamp comprising a housing with clamping elements arranged in a clamping head, which can be moved from an open position to a closed position and back via a drive.

Such a gripping device or clamping device is described, for example, in EP 0 790 106 A1. The gripping device is designed for manually operated or automatic handling devices and comprises a gripper housing, at least one base jaw slidably mounted in the gripper housing and a drive for the base jaw, the drive being formed by a hydraulically or pneumatically actuated piston slidably mounted in a cylinder and a wedge hook gear. In the known gripping device, it is provided that the workpieces to be gripped or clamped are moved by means of an automatic handling device or a travel carriage. The clamping elements are then actuated in order to clamp or grip the workpieces. Another gripping or clamping device of this type is also known from WO 01/68328 A1.
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EP O 313 947 A2 describes a clamping device with a clamping head in which the clamping elements are movably attached and which is firmly connected to the drive. The opening and closing movement of the clamping elements is achieved via a reversing lever by a back and forth movement of a rod such as a piston rod protruding from the preferably pneumatic drive. The clamping elements are each arranged so that they can pivot about a swivel joint in the clamping head and are moved via the reversing levers in the manner of pliers.

To clamp sheets to be welded for laser welding, for example, the parallel clamp known from the state of the art must be positioned in the open state as a complete unit, i.e. drive and clamping head, using a sliding unit, with the clamping elements then being closed to clamp the sheets via the drive. Due to a fixed distance between the swivel joints of the two clamping elements, parallel gripping is only guaranteed within a certain clamping dimension, which also limits the use of the parallel clamp. After opening the clamping elements, the clamping head must be moved away from the sheets to be clamped together with the drive, which also involves additional effort and work steps.

Based on this, the present invention is based on the problem of developing a parallel clamp of the aforementioned type in such a way that it is easy to move towards the objects to be clamped, whereby a high and variable clamping force can be exerted on the objects to be clamped. Furthermore, the parallel clamp should be suitable for clamping different pieces of material.

This problem is solved according to the invention in that the clamping elements are mounted in the clamping head so as to be displaceable parallel and/or perpendicular to a central axis of the clamping head, wherein the clamping head itself is arranged so as to be axially displaceable relative to the housing and can be displaced by the drive from a basic position in which the clamping elements assume an open position into a working position in which the clamping elements maintain their position relative to the clamping head in the open position and that the clamping head can be moved from the working position into a closed position, wherein the

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Clamping elements can be moved into a closed position for clamping objects due to the axial movement of the clamping head via deflection means.

The parallel clamp according to the invention has the advantage over the prior art that the clamping elements together with the clamping head can initially be brought into a working position in which the clamping elements already encompass the objects to be clamped, so that in a final step it is only necessary to move from the working position to the closed position in order to close the clamping elements. It is therefore not necessary to move the entire parallel clamp, consisting of the clamping head and drive, via a sliding carriage.

In order to achieve parallel clamping of the clamping elements, it is provided that they are arranged in a plane spanned by the objects to be clamped (clamping plane) so as to be displaceable parallel and/or perpendicular to this plane, wherein the clamping elements each have deflection means such as cams which engage in cam guides provided in the clamping head such that upon axial movement of the clamping head from the working position into the closed position, a closing movement of the clamping elements is achieved by the cam guide.

Preferably, the cam guide is designed as a slotted guide which is inclined relative to the central axis.

Furthermore, it is provided that the clamping elements are guided along at least one guide element running perpendicular to the central axis, which is connected to the drive housing via an axially extending further guide element such as a rod and is mounted in the latter in order to limit an axial movement of the clamping elements in the working position or closed position.

In a particularly preferred embodiment, the clamping elements are held in their open position by means of a spring element such as a compression spring. The spring element is designed as a spiral spring which is parallel or substantially

June 11, 2003-43254£täiSp· \ *

runs parallel to the guide elements and is held in the holders of the clamping elements.

In order to enable flexible use of the parallel clamp, it is provided that it is connected to a holder via spring elements such as spring bands that run parallel to one another and parallel to the clamping plane, which is preferably arranged on a tripod so that it can be moved in a horizontal direction.

This allows the parallel clamp to be set to a desired height, with the spring bands providing parallel compensation if the center axis of the parallel clamp is not exactly in line with the clamping axis of the objects. The tripod and the swivel axis allow the parallel clamp to be used flexibly.

Furthermore, it can be provided that one of the spring bands is acted upon by a compensating cylinder, which causes a force to act perpendicular to the plane spanned by the spring band and thus enables a fine adjustment of the positioning of the parallel clamp.

In order to ensure safe approach and clamping of metal sheets, particularly those lying on top of one another in stacks, it is provided that a clamping surface of the clamping element is arranged in an articulated manner on the clamping element, wherein the clamping surfaces of both clamping elements, in the open position, assume a V-shaped open position in the direction of the objects to be clamped.

Furthermore, it is provided that the drive is designed as a pneumatic drive, comprising a piston arranged in a cylinder, to which the piston rod for actuating the clamping head is attached. The drive can apply a clamping force F at a pressure P of P = 6 bar in the range of 1000 to 3000 N, preferably F = 2000 N. The strength of the clamping force can be variably adjusted using a pressure reducer (not shown).

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Further details, advantages and features of the invention emerge not only from the claims, the features to be derived therefrom - individually and/or in combination - but also from the preferred exemplary embodiment to be derived from the following description.
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Show it:

Fig. la, b, c a side view and top view of the parallel clamp in a

Initial position,
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Fig. 2a, b Side views of the parallel clamp in a working position,

Fig. 3 a side view of the parallel clamp in closed position,

Fig. 4a, b, c different views of the Paral mounted on a tripod

lelspanners.

Figures Ia-Ic show a side view and two top views, partially sectioned, of a parallel clamp 10 in a basic position. The parallel clamp 10 consists of a housing 12 in which a clamping head 14 is mounted so as to be movable in the axial direction. Clamping elements (16, 18) for clamping objects such as metal sheets 19, for example for a laser welding process, are arranged in the clamping head 14.

The housing 12 further comprises a preferably pneumatic drive 20, consisting of a cylinder 22 in which a piston 24 is arranged so as to be displaceable along the central or longitudinal axis 26 under the action of compressed air from a compressed air source (not shown).

The piston 24 is connected to a piston rod 28, which is connected via a flange 30 to guide elements 32, 34 of the clamping head 14.

By applying pressure to the cylinder 22 with compressed air, the clamping head 14 can be moved from the basic position shown in Fig. 1 a by a so-called travel stroke into a position shown in 11.Juni2003-43254feVfK'"''"'""'"'■'.''."'.'"."ll"''' ·

Fig. 2a and 2b shown working position. At the same time, the clamping elements 16, 18, which are mounted in the clamping head 14 so that they can move both in the axial direction and perpendicular to the axial direction, are advanced via a guide element 36 mounted in the housing 12. The clamping elements 16, 18 are held in their open position by a spring element 38, which is arranged as a compression spring between the two clamping elements 16, 18. A first end 40 of the guide element 36 is limited in the axial direction by a stop when the clamping head 14 is advanced, so that the axial position of the clamping elements 16, 18 is limited. A further guide element 44 is provided at a second end 42 of the guide element 36, which runs perpendicular to the longitudinal axis 26, i.e. perpendicular to a plane spanned by the elements to be clamped. The further guide element engages in guide receptacles 46, 48, which are each introduced into the clamping elements 16, 18 in order to enable movement transversely to the axis 26.

In the working position, the clamping elements 16, 18 are already positioned in such a way that they encompass the objects to be clamped. In order to achieve optimum clamping of the objects, the clamping elements 16, 18 are provided with movable clamping surfaces 50, 52, which in the open position form a V-shaped opening in the direction of the objects.

Finally, in Fig. 3, the parallel clamp 10 is shown in a closed position. To reach the closed position, the clamping head 14 is moved from its working position by a further axial movement of the piston 24 and the piston rod 28 in the axial direction, i.e. in the direction of the arrow 54, but without the clamping elements 16, 18 performing an axial movement, since they rest firmly against a housing wall due to the stop 40 of the guide element 36. In order to achieve a closing movement of the clamping elements 16, 18, it is provided that they each have a cam 56, 58 on both sides, which engages in a cam guide 60, 62 provided in a side wall 70 of the clamping head 14, wherein the cam guide 60, 62 is designed as an elongated hole that runs at an angle of preferably 35° with respect to the longitudinal axis or clamping plane 26. In this position, both the clamping head 14 and the clamping elements 16, 18 are held firmly to a housing wall of the housing 12 via the flange connected to the piston, so that at a pressure of, for example, P = 6 bar, a

A clamping force of approximately F = 2000 N can be achieved. Of course, it is possible to adjust the clamping force variably using a pressure reducer (not shown).

Fig. 4 a) to c) shows a fastening device 64 for the parallel clamp 10. The fastening device 64 comprises a tripod stand 66 on which a slide 68 is slidably mounted. The slide is connected to the housing 12 of the parallel clamp 10 via parallel spring elements such as spring bands 70, 72. The spring bands 70, 72 serve to compensate for a parallel compensation in the direction of the arrow 74. The dimensions can be in the range of 0 <= L < 20 mm, preferably L = 0 to 5 mm. Furthermore, a drive 76 is provided between the spring bands 70, 72, which acts in the vertical direction on at least one spring band 70 in order to mechanically effect the compensation L.

Furthermore, it is provided that the carriage 68 has a joint 78, via which the parallel clamp 10 together with the spring bands 70, 72 is mounted so as to be rotatable by 360° in the direction of the arrow 80.

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Claims (12)

1. Parallel clamp ( 10 ), comprising a housing ( 12 ) with clamping elements ( 16 , 18 ) arranged in a clamping head ( 14 ), which can be moved from an open position into a closed position and back via a drive ( 20 ), characterized in that the clamping elements ( 16 , 18 ) are mounted displaceably in the clamping head ( 14 ) parallel and/or perpendicular to a central axis ( 26 ) of the clamping head ( 14 ), wherein the clamping head ( 14 ) itself is arranged axially displaceably relative to the housing ( 12 ) and can be moved by the drive ( 20 ) from a basic position, in which the clamping elements ( 16 , 18 ) assume an open position, into a working position, in which the clamping elements maintain their position relative to the clamping head ( 14 ) in the open position, and that the clamping head ( 14 ) can be moved from the working position into a closed position, wherein the clamping elements ( 16 , 18 ) can be displaced into a closed position via deflection means ( 56 , 58 , 60 , 62 ) for clamping objects ( 19 ) due to the axial movement of the clamping head ( 14 ). 2. Parallel clamp according to claim 1, characterized in that the clamping elements ( 16 , 18 ) are arranged in a plane spanned by the objects to be clamped ( 19 ) (clamping plane) so as to be displaceable parallel and/or perpendicular to this plane, wherein the clamping elements ( 16 , 18 ) are each designed via deflection means designed as cams ( 56 , 58 ) and engaging in cam guides ( 60 , 62 ) of the clamping head ( 14 ), so that upon an axial movement of the clamping head ( 14 ) from the working position into the closed position, a closing movement of the clamping elements ( 16 , 18 ) is achieved by the cam guide ( 60 , 62 ). 3. Parallel clamp according to claim 1 or 2, characterized in that the cam guide ( 60 , 62 ) is designed as an elongated hole guide which runs inclined with respect to the central axis ( 26 ). 4. Parallel clamp according to at least one of the preceding claims, characterized in that the clamping elements ( 16 , 18 ) are guided along at least one guide element ( 44 ) running perpendicular to the central axis ( 26 ), which is connected to the drive housing via an axially extending further guide element ( 36 ) such as a rod and is mounted in the latter in order to limit an axial movement of the clamping elements in the working or closed position. 5. Parallel clamp according to at least one of the preceding claims, characterized in that the clamping elements ( 16 , 18 ) are held in their open position by means of a spring element ( 38 ) such as a compression spring. 6. Parallel clamp according to one of the preceding claims, characterized in that the spring element ( 38 ) is a spiral compression spring which runs parallel or substantially parallel to the guide elements ( 44 ) and is held in receptacles of the clamping elements ( 16 , 18 ). 7. Parallel clamp according to at least one of the preceding claims, characterized in that the parallel clamp ( 10 ) is connected to a holder via spring elements such as spring bands running parallel to one another and parallel to the central axis ( 26 ), which is preferably displaceable in a horizontal direction on a tripod. 8. Parallel tensioner according to at least one of the preceding claims, characterized in that at least one of the spring bands is acted upon by a compensating cylinder which causes a force to act perpendicular to the plane spanned by the spring band and thus enables fine compensation of the positioning of the parallel tensioner. 9. Parallel clamp according to at least one of the preceding claims, characterized in that a clamping surface ( 50 , 52 ) of the clamping element ( 16 , 18 ) is arranged in an articulated manner on the clamping element, wherein the clamping surfaces ( 50 , 52 ) of both clamping elements assume a V-shaped open position in the direction of the objects to be clamped ( 19 ) in the open position. 10. Parallel clamp according to at least one of the preceding claims, characterized in that the drive ( 20 ) is designed as a pneumatic drive, comprising a piston ( 24 ) arranged in a cylinder ( 22 ), to which the piston rod ( 28 ) for actuating the clamping head ( 14 ) is fastened. 11. Parallel clamp according to at least one of the preceding claims, characterized in that a clamping force can be applied to the objects ( 19 ) by the clamping elements ( 16 , 18 ) at a pressure P of P = 6 bar in the range from F = 1000 to F = 3000 N, preferably F = 2000 N. 12. Parallel clamp according to at least one of the preceding claims, characterized in that the clamping force F is adjustable via a pressure reducer.