Abstract
Gripping or clamping device comprising a housing body and at least one jaw guide which is provided in the housing body and has two lateral walls, including at least one jaw which can be moved in the jaw guide along a movement direction, guide surfaces being provided on the lateral walls and the jaw having sliding surfaces which interact with the guide surfaces to form a sliding guide, characterized in that at least one raceway part and rolling elements are provided in the jaw guide, the jaw and the raceway part each having a raceway for abutting against the rolling elements to form a roller guide, and in that pretensioning means are provided for generating a pretensioning force, the pretensioning force acting on the raceway part such that the rolling elements are pressed against the jaw-side raceways.
Claims
1. Gripping or clamping device comprising a housing body and at least one jaw guide which is provided in the housing body and has two lateral walls, comprising at least one jaw which can be moved in the jaw guide along a movement direction, guide surfaces being provided on the lateral walls and the jaw having sliding surfaces which interact with the guide surfaces to form a sliding guide, characterized in that at least one raceway part and rolling elements are provided in the jaw guide, the jaw and the raceway part each having a raceway for abutting against the rolling elements to form a roller guide, and in that pretensioning means are provided for generating a pretensioning force, the pretensioning force acting on the raceway part such that the rolling elements are pressed against the jaw-side raceways.
2. Gripping or clamping device according to claim 1, characterized in that the sliding guide has a clearance between the guide surfaces and the sliding surfaces, such that the guide surfaces only act against the sliding surfaces if an external force which is counter to the direction of the pretensioning force and counteracts or exceeds the pretensioning force acts on the jaw.
3. Gripping or clamping device according to claim 1, characterized in that a raceway part provided on each lateral wall, the raceway parts being arranged symmetrically with respect to one another and/or with respect to a central plane which extends in the movement direction.
4. Gripping or clamping device according to claim 1 characterized in that the raceway parts have raceways extending in parallel with one another.
5. Gripping or clamping device according to claim 1, characterized in that one raceway part has two raceways which include an angle (β, γ), and in that the jaw has sliding surfaces which extend correspondingly thereto.
6. Gripping or clamping device according to claim 1, characterized in that a plurality of guide surfaces are provided on each lateral wall, the planes in which adjacent guide surfaces are located including an acute angle (α).
7. Gripping or clamping device according to claim 1, characterized in that the jaw has at least two sliding surfaces which interact with a lateral wall, and in that at least one jaw-side raceway is arranged between said sliding surfaces.
8. Gripping or clamping device according to claim 1, characterized in that the pretensioning means are integral with the raceway part and/or the housing body.
9. Gripping or clamping device according to claim 1, characterized in that the pretensioning means are designed as spring elements provided between the housing body and the raceway part.
10. Gripping or clamping device according claim 1, characterized in that adjusting means are provided for adjusting the pretensioning force of the pretensioning means.
11. Gripping or clamping device according to claim 1, characterized in that the rolling elements are trapped in a cage, the cage having sliding portions which interact with the raceways.
12. Gripping or clamping device according to claim 1, characterized in that the rolling elements are designed as balls, barrels, rollers or needles.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In the drawings:
[0027] FIG. 1 is an isometric view of a gripping device according to the invention;
[0028] FIG. 2 shows a cross section of the gripping device according to FIG. 1;
[0029] FIG. 3 shows a cross section of an additional gripping device according to the invention;
[0030] FIG. 4 shows a detail of the device according to FIG. 3 with an adjusting means;
[0031] FIG. 5 shows a partial cross section of an additional gripping device according to the invention;
[0032] FIG. 6 is an isometric view of a detail of FIG. 5 without a jaw and without a raceway part;
[0033] FIG. 7 is the view according to FIG. 6 with a raceway part;
[0034] FIG. 8 is a view corresponding to FIG. 6 with a differently designed pretensioning means;
[0035] FIG. 9 is the view according to FIG. 8 with a raceway part, rolling elements and a jaw;
[0036] FIG. 10 shows a longitudinal section of the embodiment according to FIG. 9 along the plane X-X;
[0037] FIG. 11 shows cross sections of an additional gripping device according to the invention;
[0038] FIG. 12 shows a cross section of an additional gripping device according to the invention;
[0039] FIG. 13 shows a section along the line XIII in FIG. 12;
[0040] FIG. 14 is a force-distance diagram of a jaw of a gripping device according to the invention.
DETAILED DESCRIPTION
[0041] The gripping device 10 shown in FIG. 1 comprises a housing body 12 having a jaw guide 14 extending through the housing body 12 in the longitudinal direction. Two displaceably mounted jaws 16, 18 are provided in the jaw guide 14, which can be moved towards and away from one another along the movement direction 26, which is indicated by a double arrow.
[0042] As is also clear from the cross section according to FIG. 2, the jaw guide 14 has two mutually opposite lateral walls 22, on which guide surfaces 24 are provided. The jaws 16, 18 have sliding surfaces 26 which interact with the guide surfaces 24 to form a sliding guide.
[0043] In the embodiment according to FIGS. 1 and 2, a total of eight guide surfaces 24.1 to 24.8 are provided which interact with eight sliding surfaces 26.1 to 26.8 to form a sliding guide. The respectively adjacent guide surfaces 24.1 and 24.2; 24.3 and 24.4; 24.5 and 24.6; and 24.7 and 24.8 each include an acute angle α. Correspondingly, the associated jaw-side sliding surfaces 26.1 to 26.8 each include a corresponding acute angle α, which is in particular in the range of from 20° to 40°, and further in the range of from 28° to 32° and preferably in the range of 30°.
[0044] Overall, the lateral walls 22 and the portions of the jaws 16, 18 which interact with the lateral walls 22 are formed symmetrically with respect to a central plane 56 which extends in the movement direction 26 and lies between the side walls.
[0045] In the jaw guide 14, on the lateral walls 22, two raceway parts 30 arranged opposite each other are provided. Rolling elements 32, for example in the form of barrels or rollers, are provided between the raceway parts 30 and the relevant jaw 16, 18. The arrangement of the rolling elements 32 can in this case correspond to the arrangement in a crossed roller bearing. The raceway parts 30 provide raceways 34 for abutting the rolling elements 32. Likewise, the jaws 16, 18 provide jaw-side raceways 36 for abutting the rolling elements 32. The raceways 34 provided on a raceway part 30 each include an obtuse angle β which is in the range of 270°. In addition to the sliding guide formed by the guide surfaces 24 and sliding surfaces 26, a roller guide of the jaws 16, 18 is provided due to the provision of the rolling elements 32.
[0046] Between the housing body 12 and the raceway parts 30, pretensioning means 38 are provided for generating pretensioning forces F which press the raceway parts 30 toward the jaw 16, 18, so that the rolling elements 32 are pressed against the jaw-side raceways 36. Because the pretensioning forces F are of equal magnitude in the idle state, the relevant jaw 16, 18 is held largely centrally in the jaw guide 14. In FIG. 2, the pretensioning means 38 are designed as elastomer spring blocks; helical springs, coil springs or other spring elements can also be used instead of these elastomer spring blocks.
[0047] The sliding guide is preferably designed as a sliding guide which has clearance, which guide has clearance between the guide surfaces 24 and the sliding surfaces 26. In this case, the clearance is such that the guide surfaces 24 act against the sliding surfaces 26 when a force which acts transversely to the movement direction, counter to the relevant pretensioning force F, and counteracts or exceeds the relevant pretensioning force F acts on the relevant jaw 16, 18.
[0048] An external force of this kind can result in particular from an overload, an impact or a shock. The clearance of the sliding guide is chosen such that when external forces of this kind occur, the sliding guides come into effect before the rolling elements 32 or the raceways 34, 36 can be damaged. The roller guide is consequently protected from overload by sliding guides which come into use.
[0049] Due to the provision of the spring means and the provided pretensioning forces, the roller guide is designed to be zero clearance. This results in the jaws 16, 18 being set into motion in a very low-friction manner, and therefore easily; a slip-stick effect, as occurs in the case of simple sliding guides, is reduced and preferably prevented. If greater loads or forces act on the jaw 16, 18, the resulting force can be diverted into the housing body 12 via the sliding guide without causing damage to the roller guide.
[0050] In the embodiment shown in FIG. 2, the relevant pretensioning element 38 and the relevant pretensioning force F resulting therefrom are relatively small. It is thereby achieved that a movement of the jaws 16, 18 takes place via the roller guide without an external force acting on the jaws 16, 18. Because of the low pretensioning forces, the sliding guide comes into effect as soon as external forces act on the jaws 16, 18. It is advantageous that no stick-slip effect occurs when the jaws 16, 18 are started.
[0051] In the embodiment according to FIG. 3, as in the embodiment according to FIG. 2, a sliding guide and a roller guide are provided. Components corresponding to FIG. 2 have corresponding reference signs.
[0052] In contrast to FIG. 2, in the embodiment according to FIG. 3 the raceways 34 each include an acute angle γ in the range of preferably 90° on the raceway part 30. Providing an angle γ of 90° results in similar conditions in the direction extending transverse to the movement direction, due to the asymmetrical conditions. If the angle γ is less than 90°, this results in better properties in the z-direction, i.e. in FIG. 2 in the upward direction. If the angle γ is more than 90°, this results in better properties in the γ-direction, i.e. in the direction of the right-hand or left-hand side in FIG. 2. The rolling elements 32 are provided between the relevant raceway 34 and the jaw-side raceway 36 which corresponds thereto. In total, two rows of rolling elements 32 interact with each raceway part 30. According to the embodiment according to FIG. 2, in the embodiment according to FIG. 3, the jaw-side raceways 36 are arranged between jaw-side sliding surfaces 26.
[0053] In the embodiment according to FIG. 3, the sliding surfaces 26 and the raceways 36 form a zigzag line in the section plane shown in FIG. 3, which line extends symmetrically with respect to a central longitudinal plane, which is identified in FIG. 3 by reference sign 40. The sliding surface 26.1 in this case includes a 90° angle together with the raceway 36 adjoining said sliding surface. The two raceways 36 in turn include an angle of 90°, and the lower raceway 36 likewise includes an angle of 90° together with the sliding surface 26.2 adjoining said lower raceway, as is clear from FIG. 3.
[0054] In the embodiment according to FIG. 3, the pretensioning means 38 are designed as spring tongues which are integral with the raceway part 30. The spring-tongue-like pretensioning means 38 have free ends 42 which, in order to provide the pretensioning forces F, act against the housing body 12 in an elastically compliant manner.
[0055] Also in the embodiment according to FIG. 3, the sliding guide produced by the guide surfaces 24 and sliding surfaces 26 is a sliding guide which has clearance and is designed such that the guide surfaces 24 act against the sliding surfaces 26 when a force which exceeds the relevant pretensioning force F acts on the jaw 16, 18.
[0056] In the embodiment according to FIG. 3, by comparison with the embodiment according to FIG. 2, significantly greater pretensioning forces F are provided. As a result, the sliding guide forms an overload protection. During normal operation of the gripping device 10, the roller guide, which has comparatively large dimensions, comes into effect. The resulting forces are only absorbed by the sliding guide in the event of overload, impacts or shocks, when the external forces acting on the jaw counteract or exceed the relevant pretensioning force F. This has the advantage that the shock-sensitive roller guide is protected in the critical region by the sliding guide.
[0057] A development of the embodiment according to FIG. 3 is shown in FIG. 4. In the embodiment according to FIG. 4, adjusting means 44 are additionally provided in the form of threaded bolts which are screwed into the main body 12 to different degrees. By means of the relevant adjusting means 44, the pretensioning force F acting on the relevant raceway part 30, which is provided by the relevant pretensioning element 38, can be adjusted. For better introduction of force, a pressure plate 46 is provided between the adjusting means 44 and the raceway part 30. The embodiment according to FIG. 4 therefore has the advantage that the pretensioning force F can be actively changed, as a result of which the switchover point between the roller guide and the sliding guide can also be changed and adapted to different uses.
[0058] The embodiment shown in FIGS. 5 to 7 substantially corresponds to the embodiment according to FIG. 3, a pretensioning means 38 being provided separately from the raceway part 30 in this case. As is clear from the isometric view according to FIG. 6, the pretensioning means 38 is designed as a pretensioned leaf spring 38, which acts against the housing body 12 on one side and against the relevant raceway part 30 on the other side.
[0059] In the embodiment according to FIGS. 8 to 10, the pretensioning means 38 is designed as a wave spring which is provided between the housing body 12 and the relevant raceway part 30. In the section according to FIG. 10, it is also clear that the individual rolling elements 32 are trapped in a cage 48.
[0060] Two further embodiments of a gripping device according to the invention are shown in cross section in FIG. 11, in which components corresponding to components in the previous embodiments have corresponding reference signs. In the embodiment shown in the left-hand half of FIG. 11, pretensioning means 38 are provided as material recesses in the housing body 12. In the embodiment shown on the right-hand side in FIG. 11, the pretensioning means 38 are provided as material recesses in the raceway part 30. According to the invention, a combination of the embodiment shown in FIG. 11 is also conceivable, i.e. material recesses in the housing body 12 and also in the relevant raceway part 30.
[0061] A further embodiment is shown in FIGS. 12 and 13, in which components corresponding to the other embodiments are identified with corresponding reference signs. In this embodiment, a pretensioning means 38 in the form of a spring plate is shown on the face of the raceway parts 30 that face the housing body 12. In the edge region, the spring plate interacts with contact portions 50 of the relevant raceway part 30. In the central region, a raised portion 52 on the housing body acts against the pretensioning means. The relevant pretensioning force F is provided by elastic deformation of the pretensioning means 38.
[0062] In the embodiment according to FIGS. 12 and 13, the rolling elements 32 are arranged in a cage 48. The cage 48 has sliding portions 54 which extend in parallel with the raceways 34, 36 and are shown in FIG. 13. The sliding portions 54, together with the raceways 34, 36, can be used as a sliding guide when a force, due to which the rolling elements are resiliently compressed in the radial direction, is exceeded. In the embodiment shown in FIG. 13, the rolling elements 32 can be designed as hollow rollers or hollow needles, as a result of which they are elastically compliant in the radial direction. The compliance can be selected in such a way that the pretensioning means 38 in the form of the spring plate, as shown in FIG. 12, can be omitted. The compliant hollow rollers or hollow needles then assume the function of the pretensioning means 38.
[0063] In the embodiment shown in FIGS. 12 and 13, the guide surfaces 24 and sliding surfaces 26, which interact directly with one another, can consequently be omitted and replaced with a sliding guide, which is formed by the cage 48 or by the sliding portions 54 of the sliding guide and the raceways 34, 36. By using the rolling element cage 48 to form the sliding guide, a very compact gripping or clamping device 10 can be provided overall.
[0064] FIG. 14 shows the force F acting on a jaw 16, 18 transversely to the movement direction 26 by means of the spring travel s of the pretensioning means 38. At point P.sub.1, the pretensioning force F.sub.V acts on the jaw 16, 18. The pretensioning means 38 is compressed by the spring travel s.sub.1. If the external force F acting on the jaw 16, 18 increases from point P1, the pretensioning means 38 is compressed further by the clearance of the sliding guide s.sub.GF until the force F.sub.GF, at which the sliding guide comes into effect, is present at point P.sub.2. If the force continues to increase at point P.sub.2, this further increasing force is absorbed only by the sliding guide, which relieves the roller guide; there is then only minimal deformation due to the resilience of the materials used.
