Clamping module, in particular for a clamping device for machining workpieces

Abstract

Clamping module, in particular for a clamping device for machining workpieces, which comprises a base body (4) designed as a slide with at least one clamping jaw (8) fastened thereto, wherein the base body (4) is adjustable in the direction of the clamping force by means of a spindle (7) guided by the slide, wherein a slotted link (9) is provided in the base body (4) which is displaceable to a limited extent in the axial direction of the spindle (7) and is adjustable by the spindle (7), and effective preload springs (10) are arranged between this slotted link (9) and the base body (4) in the direction of the clamping force, by the spring force of which the base body (4) with the clamping jaw (8) fastened thereto automatically readjusts when the clamping force is released, characterized in that the preload springs (10) are placed in pairs symmetrically around the spindle (7) in the slotted link (9) and are guided there axially parallel to the spindle (7) by guide pins (11) seated in the slotted link (9).

Description

[0001] The invention relates to a clamping module, in particular for a clamping device for machining workpieces, which comprises a base body designed as a slide with at least one clamping jaw fastened thereto, wherein the base body is adjustable in the direction of the clamping force by means of a spindle guided by the latter. Such clamping modules are used, for example, in multiple clamping devices for clamping geometrically complex workpieces in machine tools, machining centers, or similar systems. This is achieved with simple manual movements by operating the spindle, which moves the clamping modules against each other. To ensure that the workpiece remains fixed during the machining process, the module's clamping jaws are equipped with embossed teeth that imprint themselves on the workpiece when clamped.

[0002] For example, DE 10 2012 000 905 A1 shows universal grip inserts for clamping systems that are inserted into clamping jaws. The teeth of the inserts penetrate the workpiece material, while the clamping contour encloses the workpiece with a defined residual force. The inserts are dimensioned and positioned using a computer program to ensure vibration-damping and positive clamping.

[0003] However, in the case of workpieces made of soft materials such as aluminum or aluminum-containing alloys, vibrations and other mechanical stresses can cause the embossing teeth to work deeper into the workpiece during the machining process, which in turn can result in a reduction in the clamping force until the workpiece is released.

[0004] GB 972 119 A describes a mechanical-hydraulic vise that can be operated from both sides—front or back. The clamping device comprises a guide rail that is axially displaceable within the base body and adjustable by a spindle, as well as a preload spring that acts between the guide rail and the base body in the direction of the clamping force. This spring force causes an automatic readjustment process when the clamping force is released. However, the preload pressure of the springs cannot be evenly distributed across the base body.

[0005] The invention is therefore based on the object of eliminating these disadvantages and of creating a spindle-operated clamping module of the type mentioned at the outset which ensures an almost constant clamping force even for workpieces made of soft materials using structurally simple means.

[0006] This object is achieved according to the invention in that a guide rail is provided in the base body which is displaceable to a limited extent in the axial direction of the spindle, which guide rail is adjustable by the spindle and between this and the base body pre-tensioning springs are arranged which act in the direction of the clamping force, by the spring force of which the base body with the clamping jaw attached to it can be automatically readjusted when the clamping force is released.

[0007] The preload springs built into the clamping module ensure that the clamping of the workpiece does not loosen in the event of vibrations, plastic deformation of the workpiece and similar influences, even in the case of workpieces made of soft materials, because its base body, which is loaded with the preload springs, automatically maintains the required clamping pressure.

[0008] In order for the preload springs to fully achieve the readjustment effect, the displaceability of the link and the spring stroke of the preload springs are matched to one another according to the invention in such a way that after the workpiece has been clamped, an adjustment stroke is still available to enable re-clamping.

[0009] The preload force of the preload springs can conveniently be adjusted using preload screws that can be screwed into the base body. To distribute the preload pressure of the springs evenly across the base body, the invention provides for the preload springs to be positioned in pairs symmetrically around the spindle in the guide rail and guided there axially parallel to the spindle by guide pins located in the guide rail.

[0010] For convenient handling, it is advantageous if the preload screws to adjust the preload force of the springs can be screwed into an end wall of the base body and are provided with a central blind hole on the back to accommodate the guide pins for the preload springs.

[0011] The latter are designed according to the invention as disc spring assemblies, whereby it is expedient both for reasons of space and with regard to the required preload force to provide preferably four disc spring assemblies, each with a plurality of disc springs arranged in the same direction

[0012] The clamping jaws are designed as embossed inserts that are screwed onto the base body. This makes it possible to vary the profile of the clamping jaws as needed.

[0013] The invention is explained in more detail below using an exemplary embodiment with reference to the drawing. In the drawings: Fig. 1 a clamping device with a clamping module according to the invention, shown in perspective, Fig. 2 a front view of the clamping device according to Fig. 1, Fig. 3 a section of the clamping device along the line III-III according to Fig. 2, Fig. 4 a perspective view of the clamping module and the link with the clamping screws according to Fig. 1 from the bottom, Fig. 5 a section of the clamping module and part of the frame, and Fig. 6 a detail VI of the preload spring according to Fig. 5, shown enlarged.

[0014] The clamping device 1 according to Fig. 1 to Fig. 3 has two clamping modules 2 and 3, whose base bodies 4, designed as slides, are guided in a frame 5 with guide grooves 6 and can be moved towards or away from each other in opposite directions by means of a spindle 7 guided through them. Clamping jaws 8 designed as embossing inserts are fastened to the clamping modules 2, 3. The spindle 7 is rotatably held in the center by a bearing 7' on the frame 5. The clamping module 2 is designed according to the invention, and actuation takes place here via a link 9 in the base body 4, which is movable to a limited extent in the axial direction of the spindle 7 and into which the spindle 7 is screwed.

[0015] In the described embodiment, the other clamping module 3 is conventionally designed, being actuated directly by the spindle 7 screwed into it. In principle, however, it could also be equipped according to the invention.

[0016] Conveniently, the base body 4 is provided with an opening 18 on its underside through which the guide 9 can be installed. The preload springs 10 can, in turn, be inserted through the front wall 16 of the base body.

[0017] Between the base body 4 and the link 9 there are four preload springs 10 placed in pairs symmetrically around the spindle 7, which - as can be seen from Fig. 4 to 6 - are guided on guide pins 11 located in the link 9, axially parallel to the spindle 7. The preload springs 10 acting in the direction of the clamping force are designed as disc spring assemblies, each with a plurality of disc springs 12 arranged in the same direction.

[0018] The distance 14 formed between the guide 9 and the base body 4 and the spring stroke of the preload springs 10 are coordinated such that, after the workpiece has been clamped, an adjustment stroke is still available to allow re-clamping. The preload force of the preload springs 10 can be adjusted using preload screws 15, which are screwed into the front wall 16 of the base body 4 and are provided with a blind bore 17 on the front side for accommodating the guide pins 11.

[0019] In Fig. Figure 3 illustrates the clamping module 3 with the clamping jaw 8 in the relaxed state. In this state, the guide 9 is retracted by the preload force of the preload springs 10 until its rear surface 9' strikes the opening 18 in the base body 4.

[0020] In the clamped state, the link 9 is loaded by the tensile force of the spindle 7 and with it the base body 4 with the clamping jaw 8 is pressed against the workpiece. If in this state the clamping force exerted on the workpiece by the clamping module 2 drops, for example because the embossed teeth of the clamping jaws imprint themselves deeper into the workpiece as a result of vibrations or other effects, the base body 4 with the clamping jaw 8 is automatically readjusted by the preload springs 10 until the full clamping force is still exerted on the workpiece. The distance 14 is reduced compared to the unclamped state. If the clamping force decreases for the reasons mentioned, the link 9 remains fixed, while the base body 4 is pressed against the workpiece by the spring force between it and the link and the contact force is maintained, whereby this distance 14 increases slightly.

[0021] The required preload of the preload springs 10 can be adjusted on a case-by-case basis by operating the preload screws 15. The type, number, and arrangement of the preload springs 10 can, of course, vary depending on the operating conditions. For example, it is in principle possible to use coil springs or similar springs instead of disc springs, as well as to use more or fewer than two pairs of preload springs.

[0022] The clamping module 2 according to the invention is characterized by the fact that it maintains the clamping force exerted on workpieces made of soft materials, even when the stamping teeth penetrate deeper into the workpiece due to vibrations and similar influences. Another particularly advantageous feature is that no springback occurs during the machining process, and that the clamping module according to the invention has the same external dimensions as conventionally designed clamping modules, making it easy to retrofit correspondingly designed clamping devices. It also enables direct stamping without re-clamping during component assembly.

Claims

[1] Clamping module, in particular for a clamping device for machining workpieces, comprising a base body (4) designed as a slide with at least one clamping jaw (8) attached thereto, wherein the base body (4) is adjustable in the direction of the clamping force by means of a spindle (7) guided through it, wherein a cam (9) is provided in the base body (4) which is displaceable within limits in the axial direction of the spindle (7) and which is adjustable by the spindle (7), and effective preload springs (10) are arranged between this cam (9) and the base body (4) in the direction of the clamping force, by means of whose spring force the base body (4) with the clamping jaw (8) attached thereto automatically readjusts itself when the clamping force decreases, characterized by , that the preload springs (10) are placed symmetrically in pairs around the spindle (7) in the cam (9) and are guided there parallel to the spindle (7) with guide pins (11) located in the cam (9). [2] Clamping module according to claim 1, characterized by , that the distance (14) formed between the cam (9) and the base body (4) and the spring stroke of the preload springs (10) are coordinated so that after clamping the workpiece there is still an adjustment stroke that allows re-tensioning. [3] Clamping module according to claim 1 or 2, characterized by , that the preload force of the preload springs (10) is adjustable by means of preload screws (15) which can be screwed into the base body (4). [4] Clamping module according to claim 3, characterized by , that the preload screws (15) can be screwed into an end wall (16) of the base body (4) and are provided on the rear side with a central blind bore (17) for receiving the guide pins (11) for the preload springs (10). [5] Clamping module according to claim 4, characterized by, that the preload springs (10) are designed as disc spring assemblies and the cam (9) is provided with preferably four disc spring assemblies, each with a plurality of disc springs (12) arranged in the same direction. [6] Clamping module according to one of claims 1 to 5, characterized by , that the clamping jaws (8) are formed by embossing inserts attached to the base body (4). [7] Clamping module according to one of claims 1 to 6, characterized by , that the base body (4) is provided on the underside with an opening (18) through which the cam (9) can be installed therein, while the preload springs (10) can be inserted through the front wall (16) of the base body (4) and connected to the cam (9).

Images