Floating clamp

Abstract

Floating clamp for clamping a workpiece in a processing machine with a first wedge bar (52, 104, 204) and a second wedge bar (62, 106, 206), and a piston (70, 130, 230, 342) which is designed to exert a pushing movement in the pushing direction (20, 80, 140, 240) for clamping the workpiece, wherein the first wedge bar (52, 104, 204) is movably received in a first recess in a first support bolt (110, 210) and the second wedge bar (62, 108, 208) is movably received in a second recess in a second support bolt (112, 212), the first wedge rod (52, 104, 204) and the first recess are directed at a first wedge angle to the thrust direction (20, 80, 140, 240) which is greater than 0°, and the second wedge rod (62, 108, 208) and the second recess are directed at a second wedge angle to the thrust direction (20, 80, 140, 240) which is greater than 0°, a first clamping means (120, 220) is assigned to the first support bolt (110, 210) and a second clamping means (122, 222) is assigned to the second support bolt (112, 212), and the first wedge rod (52, 104, 204) and the second wedge rod (62, 108, 208) are connected to the piston (70, 130, 230, 342) via a rotatably mounted cross connection (72).

Description

The invention relates to a floating clamp which serves for clamping a workpiece in a processing machine.Floating clamps are mechanical clamping elements for clamping and supporting, in particular, overdefined or additional clamping points and generally enable low-distortion clamping of components or workpieces. Floating clamps are thus workpiece clamps, the task of which is to fix and retain a component or workpiece to be mechanically machined on a machine tool in its position, so that the latter resists the machining forces.It should be taken into account that, in order to tension a workpiece in a processing machine in a statically determined manner, three support points and three workpiece tensioners are required. However, in the case of larger components, it is not sufficient to tension on the three bearing points. In this case, tensioning must be carried out at further points in order to ensure stable tensioning. However, since the workpiece is statically determined by the three points in the processing machine, further clamping points must operate in a floating manner. For this purpose, floating clamps, which are also referred to as compensating clamps, are used.Against this background, a floating tensioner according to claim 1 is presented. Embodiments will be apparent from the dependent claims and from the description.The floating clamp presented serves for clamping a workpiece and is used, for example, in a processing machine. The floating tensioner includes a first wedge rod and a second wedge rod, and a piston configured to apply a thrust motion in the thrust direction for clamping the workpiece. For clamping and releasing the workpiece, the piston is thus guided back and forth in a thrust direction, typically guided.The first wedge rod is movably received in a first recess in a first support bolt. Accordingly, the second wedge rod is movably received in a second recess in a second support bolt. This means that the wedge rods can each be moved back and forth in the associated recess, which is formed corresponding to the wedge rod.The first wedge rod and the first recess are directed at a first wedge angle to the direction of thrust that is greater than 0°. Accordingly, the second wedge rod and the second recess are directed at a second wedge angle to the direction of thrust that is greater than 0°. A movement of the wedge rods, which are typically guided, thus leads to a movement of the respective supporting bolt, which are likewise regularly guided, in a clamping direction, which in turn is typically substantially transverse to the direction of thrust.A first clamping means is assigned to the first support bolt, and a second clamping means is likewise assigned to the second support bolt. Movement of the piston in the thrust direction causes movement of the wedge rods also in the thrust direction. By means of the cooperation of the alignment of the wedge rods and the correspondingly aligned recesses in the support bolts in conjunction with suitable guides, the support bolts move opposite to one another in a plane parallel to the clamping direction and substantially perpendicular or transverse to the pushing direction.Furthermore, the first wedge rod and the second wedge rod are connected to the piston via a rotatably mounted transverse connection. This realizes the floating mounting of the wedge rods.Floating clamping is understood here in particular to mean a position-flexible clamping which is possibly also useful for supporting the workpiece.The floating clamp presented is distinguished in that it can retain a workpiece in regions without influencing its position or shape. This can ensure that in particular unstable workpieces can be supported and that the machining forces do not deform the workpiece. In addition, oscillations on the workpiece can be damped or even eliminated. This is achieved in that the components involved in the clamping act smoothly on the workpiece with the smallest possible force and in that a holding force is subsequently generated which holds the workpiece firmly without changing its position or shape. External forces, on the other hand, which act on the workpiece at this point oppose the greatest possible resistance.The rotatably mounted transverse connection can be designed as a pendulum drive and can also have a rocker independently thereof.Furthermore, the clamping means can be designed as clamping jaws, with which the workpiece can be securely clamped.In addition, the clamping jaws can each be connected to the associated support bolt via one or more push rods or tie rods.In a further embodiment, the wedge angles are less than 25°. This enables a reliable transmission of the thrust movement of the piston to the clamping means. However, a force effect on the clamping means, for example caused by a machining of the workpiece, counter to the clamping direction does not cause a movement of the piston counter to the thrust direction.The wedge angles can be in a range between 1 and 25°. Typically, the two wedge angles are the same. However, it is also conceivable for the two wedge angles to be different.The piston can be actuated mechanically, hydraulically and / or pneumatically.In the case of hydraulic or pneumatic actuation, it is appropriate if necessary seals are arranged before the transverse connection.Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.BRIEF DESCRIPTION OF THE DRAWINGFIG. 1 shows an exploded view of a greatly simplified schematic component of a floating tensioner presented. FIG. 2 shows the components from FIG. 1 in an operable arrangement. FIG. 3 shows further components of the floating tensioner presented. FIG. 4 shows embodiments of the presented float tensioner in several representations. FIG. 5 shows a further embodiment of the floating tensioner presented in several representations.Embodiments of the InventionThe invention is schematically illustrated in the drawing on the basis of embodiments and is described in detail below with reference to the drawing.FIG. 1 shows a greatly simplified schematic illustration of a wedge slide 10 which carries a wedge rod 12, and a supporting bolt 14. Correspondingly aligned or formed, a recess 18 is provided in the support bolt 14. This recess is likewise formed in the support bolt 14 rotated by the wedge angle 16 and is configured to partially or completely receive the wedge rod 16.FIG. 2 also shows the wedge slide 10 with the integrally formed wedge rod 12 which now extends partially into the recess 18 in an operational manner. This means that the wedge rod 12 is partially accommodated in the recess 18. If the wedge rod is now moved together with the wedge slide 10 upward in the direction of thrust 20, wherein the movement of the wedge slide 10 and thus at least indirectly the movement of the wedge rod 12 is guided, the support bolt 14, if a movement upward is inhibited in the latter, moves leftward in a clamping direction 22.The wedge angle (reference numeral 16 in FIG. 1 ) affects the relationship between vertical movement and horizontal movement. Since the wedge angle is smaller than 25° here, a good transfer of the vertical movement of the wedge rod 12 into the horizontal movement of the supporting bolt 14 is ensured. On the other hand, a force on the support bolt 14 in the horizontal direction, which force is caused, for example, by machining a clamped workpiece, does not cause any movement of the wedge rod 12 and thus of the wedge slide 10 in the horizontal direction.FIG. 3 shows a first wedge slide 50 with a first wedge rod 52 and a second wedge slide 60 with a second wedge rod 62, The slopes of the wedge rods 52, 62 are defined via a first wedge angle 54 and a second wedge angle 64. The illustration also shows a central piston 70, on which a transverse connection 72 is rotatably mounted about a bearing point 74. A movement of the piston 70 in the thrust direction 80 brings about corresponding movements of the two wedge slides 50, 60 or of the two wedge rods 52, 62, respectively.For reasons of clarity, neither the support bolts assigned to the wedge rods 52, 62 (see FIGS. 1 and 2 ) nor any clamping means are reproduced in the illustration. The special connection via the transverse connection 72 enables floating clamping of a workpiece with the clamping means or clamping jaws. If one of the two clamping means abuts the workpiece, then initially in the further course only the other clamping means moves in the clamping direction towards the workpiece. Only when both clamping means bear against the latter is a clamping force exerted by both clamping means on the workpiece.FIG. 4 shows two embodiments of the floating tensioner presented in several representations.The illustration shows at the top in illustrations I and II a floating tensioner, which is denoted overall by the reference numeral 100. A first wedge slide 102 with a first wedge rod 104 and a second wedge slide 106 with a second wedge rod 108 can be seen. The first wedge rod 104 interacts with a first supporting bolt 110. The second wedge rod 108 interacts with a second support bolt 112. The support bolts 110, 112 are in turn each connected to a clamping means 120, 122. Furthermore, a piston 130 is provided which is connected via a rotatably mounted rocker 132 to the two wedge slides 102, 106 and thus to the two wedge rods 104, 108.A movement of the piston 130 back and forth in a thrust direction 140 brings about a movement of the two clamping means 120, 122 towards one another or away from one another in the clamping direction 142. It can be seen that in the operating position on the left-hand side, in which the wedge rods 104, 108 have moved further into the recesses in the support bolts 110, 112, the clamping means 120, 122 are located further away from one another. Depending on the type of workpiece and the type of clamping, illustration I or illustration II may show the clamped operating position.Furthermore, the illustration at the bottom in illustrations III and IV shows a floating tensioner which is denoted overall by the reference numeral 200. A first wedge slide 202 with a first wedge rod 204 and a second wedge slide 206 with a second wedge rod 208 can be seen. The first wedge bar 204 interacts with a first support bolt 210. The second wedge rod 208 interacts with a second support bolt 212. The support bolts 210, 212 are in turn each connected to a clamping means 220, 222. Furthermore, a piston 230 is provided, which is connected via a rotatably mounted rocker 232 to the two wedge slides 202, 206 and thus to the two wedge rods 204, 208.A movement of the piston 230 back and forth in a thrust direction 240 brings about a movement of the two clamping means 220, 222 towards one another or away from one another in the clamping direction 242. It can be seen that in the operating position on the left-hand side, in which the wedge rods 204, 208 have moved further into the recesses in the support bolts 210, 212, the clamping means 220, 222 are located further away from one another.Illustrations I and II illustrate the clamping of a relatively large workpiece. The embodiment of FIGS. III and IV serves, for example, for clamping a workpiece on a rib or can be used for so-called inner clamping.Illustration V shows the situation in which the wedge bars 104, 108 are mounted, and they are thus not yet mounted.Representations VI and VII show side views.FIG. 5 shows a further embodiment of the float clamp 300 in different representations. Illustration I shows the floating tensioner 300 from above, illustration II shows the floating tensioner 300 from the side, and illustration III shows the floating tensioner 300 from below. A section along line A-A is shown in Figure IV.Illustration I shows a first jaw 302, a second jaw 304, a first push rod 306, first hexagon socket screws 308, and a housing 310.Illustration II shows second hexagon socket screws 320, a second push rod 324, and a further push rod 326.Illustration III shows an O-ring 330 and further hexagon socket screws 332.Illustration IV shows a receiving bolt 340, a piston 342, a thrust washer 344, a rocker 346, a base plate 348, an internally threaded cylinder pin 350, a receiving bolt 352, the housing 310, an axle 352, a piston seal 354, and an O-ring 356.Two clamping jaws are thus used for clamping, as they are also used, for example, in two-jaw chucks. In the conventional jaw chuck, the clamping jaws operate centrally, i.e. the workpiece is clamped in a centering manner. However, the object to be achieved here requires a chuck which does not center the workpiece, i.e. forces it into a specific position. The workpiece, on the other hand, should remain at the position in which it is located and be supported there. The two clamping jaws which clamp the workpiece are controlled or actuated by a respective wedge rod.In a known two-jaw chuck, the wedge rods must be guided absolutely synchronously. In the floating clamp presented, however, the wedge rods and thus the clamping means or clamping jaws do not move synchronously but at will. Therefore, as a rule, a clamping jaw will first reach the workpiece. There, their movement through the workpiece is stopped and the other clamping jaw continues to move until the latter has also reached the workpiece. Previously, no forces must build up because these forces would load the workpiece on one side and press it out of its position or shape. Only when both clamping jaws abut the workpiece does the actual clamping forces build up. This should also be done very uniformly on both sides. The smooth pendulum movement of the wedge rods required for this is achieved in that the entire movable arrangement is very smooth. No appreciable frictional forces must inhibit the movements. This is achieved in that no seals prevent ready running on the components involved.If a clamping jaw is in contact with the workpiece in a manner driven by the associated wedge rod, it can no longer be displaced in its position by forces on the clamping jaw. This is achieved in particular by the flat wedge angles which, on the one hand, multiply the forces during clamping and, on the other hand, do not yield to a counterforce.The floating tensioner presented can be actuated hydraulically or pneumatically as well as mechanically. For the build-up of force in the hydraulic and pneumatic embodiment, seals are required which, however, may greatly inhibit ready running and thus supply the floating with excessively strong undesired asymmetric forces. This can be avoided by locating these seals, which contribute to the stroke, in the middle of the chuck in front of the pendulum drive.

Claims

A float clamp for clamping a workpiece in a processing machine, comprising a first wedge rod (52, 104, 204) and a second wedge rod (62, 106, 206), and a piston (70, 130, 230, 342) configured to exert a thrust movement in the thrust direction (20, 80, 140, 240) for clamping the workpiece, wherein the first wedge rod (52, 104, 204) is movably received in a first recess in a first support bolt (110, 210) and the second wedge rod (62, 108, 208) is movably received in a second recess in a second support bolt (112, 212), the first wedge rod (52, 104, 204) and the first recess are directed at a first wedge angle to the thrust direction (20, 80, 140, 240) that is greater than 0°, and the second wedge rod (62, 108, 208), 208) and the second recess are directed at a second wedge angle to the direction of thrust (20, 80, 140, 240) that is greater than 0°, a first clamping means (120, 220) is associated with the first support bolt (110, 210) and a second clamping means (122, 222) is associated with the second support bolt (112, 212), and the first wedge rod (52, 104, 204) and the second wedge rod (62, 108, 208) are connected to the piston (70, 130, 230, 342) via a rotatably mounted transverse connection (72).Floating tensioner according to claim 1, in which the rotatably mounted transverse connection (72) is designed as a pendulum drive.Floating tensioner according to claim 1 or 2, wherein the rotatably mounted transverse connection (72) has a rocker (132, 232, 346).Floating clamp according to one of Claims 1 to 3, in which the clamping means (120, 122, 220, 222) are designed as clamping jaws (302, 304).Floating clamp according to one of Claims 1 to 4, in which the clamping jaws (302, 304) are each connected to the associated supporting bolt via a push rod (306, 326).Floating tensioner according to one of claims 1 to 5, wherein the wedge angles (16) are less than 25°.Floating tensioner according to claim 6, wherein the wedge angles (16) are in a range between 1 and 25°.Floating tensioner according to one of claims 1 to 7, wherein the piston (70, 130, 230, 342) is mechanically actuatable.Floating tensioner according to one of claims 1 to 7, wherein the piston (70, 130, 230, 342) is hydraulically actuatable.The float tensioner of any of claims 1 to 7, wherein the piston (70, 130, 230, 342) is pneumatically operable.Floating tensioner according to claim 9 or 10, wherein seals are provided which are arranged before the transverse connection (72).Floating tensioner according to one of claims 1 to 11, wherein the wedge rods (12, 52, 62, 104, 108, 204, 208) are each part of a wedge slide (10, 50, 60, 102, 106, 202, 206).

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