SK5332002A3 - Clamping device for workpieces - Google Patents

Abstract

Clamping fixture has base (1) and workpiece bracket (2) which can be firmly clamped on it, on which they are arranged directional links (5, 10, 27, 28) that cooperate with the pair and the workpiece holder (2) aligns in three on perpendicular coordinate axes and angular to pedestal (1). Several clamping bodies (4, 11) hold their hold the clamping force (2) of the workpiece in the position specified directional links, on the pedestal (1). Each clamping body has a clamping sleeve (4) on the pedestal (1) and on the handle (2) workpiece clamping pin (11). As directional articles for determination the position in the coordinate axis, parallel to the efficiency line the clamping force, there are abutting stops areas (27, 28). In order to construct the workpiece grip (2) as simple and cost-effective as possible this on the side (9) in the clamped state facing the pedestal (1) continuously flat surface that locally on this side (27) and on which they are on directional elements (10) are fixed on the side to determine the co-ordinate as well as the clamping pins (11).

Description

Workpiece fixture

Technical field

The present invention relates to a fixture for position-defined clamping of a workpiece at a machine tool workstation, with a stand fixed at a machine tool workstation and a workpiece grip that can be seated and firmly clamped thereon, further with directional elements on the workpiece stand and gripper The workpiece cooperates in a paired manner and aligns the workpiece grip in three mutually perpendicular coordinate axes (X, Y, Z) and angled on the pedestal, and with a fixture whose clamping force firmly holds the workpiece grip in a position determined by directional links on the pedestal.

BACKGROUND OF THE INVENTION

Clamping jigs of this type are to be suitable, when appropriately sized, for clamping relatively large and heavy workpieces, and to this end they can transmit the forces that occur during machining with chip removal, without affecting the required positioning accuracy.

The development of larger fixtures is based on the experience of smaller fixtures. In one of the known fixtures of smaller construction, two linear pairs of directional elements for determining the angular position are arranged in a circle around the central fixture, in the coordinate plane (XY) formed by the two coordinate axes (XY), the third coordinate axis (Z) and the working sides of the wedge centering ruler and the working edge respectively extend radially to the Z axis formed by recesses in a common plate that is yieldable in the Z axis direction. This plate is located on the workpiece holder while the centering rulers are attached on the pedestal, the clamping jig consists of a clamping sleeve disposed in the pedestal with a ball closure and a clamping pin protruding on the workpiece clamp that can be inserted into the clamping sleeve on the pedestal to clamp the workpiece clamp. To determine the position in the Z-axis, pins, centrally symmetrically placed on the workpiece clamp, which face the stop faces on the base with their face.

centering crevices Centering crevices are

The clamping jigs in this embodiment have a high reproducibility of the workpiece grip position relative to the base and have recently proven to be positionally defined for workpiece gripping, especially when the forces exerted on the workpieces during the machining process are negligible, as in electroerosion machining.

In machining with chip removal, the load-bearing capacity of such a clamping device limits their field of application substantially to a workpiece whose dimensions are not larger than the dimensions of the actual fixture. When machining larger workpieces, forces may occur on the fixture, which in some circumstances become so large that the linear direction elements and the fixture are overloaded and their function can no longer be performed in any way, and in particular can no longer perform with the required accuracy. Particularly critical are the rotational moments exerted by the machining forces on the workpiece holding with respect to the Z axis, which can generate excessively high compressive forces on the working flanks of the pairs of directional links for determining the X and Y axes, which affect the positioning accuracy. These compressive forces can be held within their respective limits by providing larger clamping jigs for machining larger workpieces, wherein said linear pairs of directional links are correspondingly stronger and have a sufficiently large radial distance from the Z axis. it is suitable for its design to be adapted to the size of the workpieces to be machined by simply increasing its dimensions. In particular, the central arrangement of the fixtures appears to be unsuitable, since a single clamping organ would be correspondingly large due to the higher clamping force. The fixture would thus become considerably clumsy and heavy and thus unsuitable for practical use. Another difficulty exists with respect to the positioning pins in the Z axis.

If these pins are at a greater distance from the clamping force efficiency line, it is necessary to take into account the deflection of the workpiece grip, which affects the positioning accuracy. On the other hand, when the pins are arranged close to the clamping force efficiency line, tipping moments may occur, which for the same reason are undesirable.

treatment, arrangement

It is an object of the present invention to provide a larger load clamping device which is improved in view of the above drawbacks. A number of other aspects should also be taken into account. On the one hand, the fact that a much larger number of workpiece clamps are required at the manufacturing plant than the corresponding supports should be taken into account to a greater extent by decisively reducing the cost of the workpiece clamping. On the one hand, the user of such fixtures has to be provided by their supplier in order to be able to use the workpiece clamps of his own development.

The object of the invention is therefore to provide a fixture of the initially mentioned type, which is simple, cost-effective in particular with respect to the workpiece grip, and which ensures that the positioning accuracy required is designed to be adaptable and favorable to all loads.

SUMMARY OF THE INVENTION

Fixture for position-defined workpiece clamping at a machine tool workstation, with a machine-fixable base and a workpiece clamp that can be laid and firmly clamped on it, with directional elements on the base and workpiece clamp, cooperate in a paired manner and align the workpiece grip in three perpendicular coordinate axes (X, Y, Z) and angularly on the pedestal, and with a fixture whose clamping force firmly holds the workpiece grip in a position determined by directional links on the pedestal; is a combination of at least two of the following characters:

as pairs of direction elements for positioning in the coordinate axis Z parallel to the clamping force efficiency line, there are opposing stop surfaces on the base and on the workpiece holder, while for positioning the two remaining coordinate axes X, Y are for each coordinate axis two linear pairs of directional links, each having one wedge centering ruler and one counterpart with one centering slot aligned thereon.

the clamping fixture comprises a plurality of clamping members having one clamping pin arranged on the workpiece holder and a clamping sleeve arranged on the base.

the workpiece holder has a flat surface on the side in the clamped state facing the base, which forms locally on this side the abutment surfaces and on which linear directional elements are fixed on this side to determine the X, Y and Z coordinate axes as well as clamping pins authorities.

With this concept, the workpiece holder can be formed by a simple plate with planar side faces, which must be provided, for example, only with holes or threaded holes for fastening said linear direction elements and clamping pins and for fastening the workpiece by means of screws. This embodiment is not only the most cost-effective, but also offers the possibility that the workpiece grip of other origin can be adapted to the location of the directional links and the clamping pins with respect to a particular base without great demands.

The workpiece forming plate preferably has through holes for receiving screws for fastening on this side of the linear direction members and clamping pins so that all the fastening screws can be operated from the side of the plate facing away from the members to be fastened. Moreover, if the fastening screws have a radial clearance in the respective through holes, the exact position of the clamping pins and in particular of the linear direction links can be determined by placing the workpiece holder with loosely mounted direction elements and clamping pins on the finished pedestal. In this way, the members to be fastened are oriented towards the counterparts on the pedestal. Then, the fastening screws may be tightened to fix the position occupied by said members. In this way, the clamps for said members, which need to be manufactured with high precision, are eliminated, and the assembly costs can be greatly reduced by the said calibration method. Furthermore, it also makes it easier for manufacturers of their own workpiece fixtures to assemble the supplied direction elements and clamping pins themselves with the required accuracy.

With respect to the Z-axis abutment surfaces, the preferred embodiment is that the abutment surfaces associated with the pedestal are annular surfaces offset from the upper side of the pedestal, which are arranged just concentrically on the collet and adjoin the movement space for the clamping pin. . In this way, it is to be achieved that the abutment surfaces receiving the clamping force are as close as possible to its center of efficiency so that the bending forces exerted by the clamping forces on the plate are kept as low as possible. Furthermore, the surface area of the abutment surfaces should be as large as possible in order to obtain sufficiently large frictional forces which counteract the mutual displacement of the abutment surfaces which just cooperate under the influence of transverse forces and thus prevent lateral displacement of the workpiece grip with respect to the base.

Preferably, the area of each annular surface is several times larger than this clamping pin at the most stressed location of its longitudinal dimension. Under these circumstances, there is a guarantee that the position of the tool carriage does not change outward across the tolerance limits even in the X / Y plane, even under heavy transverse loads, and that the respective pairs of directional links do not overload.

In order to determine the coordinate axes (X, Y, Z), a solution is known, in principle known, in which each pair of directional links has a wedge centering ruler and a counterpart with a centering slot aligned therewith. In this case, it is recommended that the counterpart of the linear pairs of directional links for determining the coordinate axes (X, Y, Z), cooperating with the wedge ruler, has a member yielding in the Z axis direction transversely to the Z axis, there is a centering slot, preferably a member having a centering slot is located in the center of the counterpart between the two fastening strips and is connected to the fastening strips by a bend-elastic rib. Since the counterparts occupy more surface space than the centering pins, it may be expedient, in view of the space requirement of the clamping members, to fasten the counterparts having a centering slot to the tool support, since the clamping pins require less space than the counterclamping bushes on the pedestal.

By arranging the clamping members and the linear directional links close to the periphery of the clamping fixture, a free space for accommodating a smaller fixture can be held in the middle. The larger fixture forms a support for the smaller fixture and can optionally be used for larger or smaller workpieces with this additional option.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, an exemplary embodiment of the invention is explained in more detail below. In the picture it means:

Fig. 1 is a top view of the fixture pedestal,

Fig. 2 a cross-section of a support fixture,

Fig. 3 is a bottom view of the workpiece fixture;

Fig. 4 is a cross-sectional view of a workpiece fixture; and

Fig. 5 is a cross-sectional view of the fixture of FIG. ^: L to 4, the positioning of the workpiece grip and firmly clamped on the base.

DETAILED DESCRIPTION OF THE INVENTION

The clamping jig shown comprises a base 11 (FIGS. 1 and 2) and a workpiece holder 2 (FIGS. 3 and 4) which can be mounted on the base 1 and can be clamped thereon in a defined position.

The base 1, which can be fixed at a work station of a machine tool or, optionally, a measuring station, has a plate cover 2 ^{with a} quadratic base surface. Inside there is a clamping device which comprises four ball-shaped clamping sleeves 5, which are centrally symmetrically arranged in four corners of the housing 2 according to FIG. 1. Further, on the upper side of the housing 2 ^there are four linear directional links 5 which are arranged relative to each other crosswise and between two adjacent clamping sleeves 4. In the center of the housing there is a clearance (indicated by a dotted circle 6 in FIG. 1), which can be received in a manner known per se by a pedestal of a smaller construction, for example in the embodiment described at the beginning. The means for fixing the base 1 to the work place are known per se and are not shown.

on here

The workpiece holder 2 which can be mounted on and clamped on the base 7 is formed by a plate 7 with planar side surfaces 8 and the workpiece to be machined is fixed in a known manner on the upper side surface 13. The means necessary for this, for example threaded holes, provided in the plate 7 are not shown in the figure. The lower side surface 9, which in the clamped state of the workpiece holder 2 faces the base 1, forms a continuously flat surface on which it is fastened on this side by means of screws 12 or 13, so-called. Linear directional links 10 and clamping pins 11 of the fixture, paired with the directional links 5 on the base A · Through holes are provided for the fastening screws 12, 13 in which the fastening screws have a radial clearance.

Each clamping sleeve 6 provided on the pedestal 1 comprises a clamping sleeve 14 which is fastened to the housing 3 of the pedestal 1 by means of screw recesses and has a hollow space 16 on the clamping pin 11. The hollow space 16 is in the inlet section 17 of the clamping sleeve. 14 conical widened outwards. To this inlet section 17 is connected an annular section 18 which is provided with a ball closure with a ring of radially movable closing balls 19. The closing balls 19 are actuated in the clamping process by means of a piston 20 which is loaded with pressure medium and which is in the cylindrical space. 21 of the cover 2 ^{and the} annular collar 22 surrounds the annular portion 18 of the collar 14. The weakly conical inner surface of the annular collar 22 is more conically widened outwardly in its end region, the hollow conical annular member 22 cooperating in a known manner with ball shutter 19 . The feed lines for the pressurized medium to the upper or lower portions are referred to as 23 and 24. In addition, the piston 20 is arranged, under the influence of the compression springs 25 which support the cylindrical space on both sides of a certain number, on a cover plate 26 closing downwards.

The upper faces 27 of all the clamping sleeves 14 lie in a plane spaced from the upper side of the housing 3 and form an annular abutment surfaces on which the lower face 2 of the plate 17 is shown. These surfaces 27 and 28, cooperating in pairs with their surface forming the workpiece grip 2 on the board in a stop manner, form pairs of directional links for determining the position of the workpiece grip 2 in the Z axis. There may be means on the pedestal 5 which allow the abutment surfaces 27, 28 to be cleaned before being joined in a manner known per se. For this purpose, compressed air channels can be provided which open on the end faces 27 of the clamping sleeves 14.

Linear directional links 5 provided on a pedestal

1 and 2, which are inserted in the grooves therein, are fixed by means of screws longitudinally centering the prismatic centering rulers 31 of the cover 3 and are 32.

rulers

The protruding 30 forms wedge surfaces 33, extending in relation to each other in a wedge-like profile, the wedge angle being about 7 ° on both sides. The assembly of the centering rulers 30 is not critical with respect to their exact position, since it is precisely after assembly that they can be ground together to the exact dimension in the mating wedge surfaces 33 of a pair of opposing centering rulers 30.

Each directional member 10 of the workpiece holder 2, designated as a counterpart with a centering slot, cooperating with the linear directional member 5 of the pedestal 5 is shown in FIG. 3 and 4, a profiled plate 40 with a central member 42 located between two fastening strips 41 has a groove 43 with a wedge-shaped side surfaces 44 as the centering slot, the wedge angle again being approximately 7 ° on both sides. The central member 42 is connected to the fastening strips 46 by means of resilient ribs 46 and in this way forms a rigid member yieldable in the direction of the axis 6, transverse to the axis 6, on the other hand, rigid. Each of the clamping pins 11 cooperating with the clamping sleeve 14 has, according to FIG. 4, at its free end a ridge 50 which is delimited at its rear by a conical annular surface 51 with which the closing balls 19 of the clamping sleeve 14 cooperate.

Fig. 2 shows the pedestal 1 at rest. The pistons 20 of the collet 4 are without pressure under themselves under the influence of the compression springs 25 which hold the pistons 20 in the stop on the clamping sleeve 14. In this piston position the ball shut-off balls 19 are in the extreme shut-off position. prevent the sealing balls 19 from falling from their position into the cavity 16 of the closing sleeve 14.

To prepare the base 1 for clamping the workpiece grip j? the upper side of the piston 20 is loaded with a pressurized medium, for example compressed air, through the inlet ducts 23, such that the pistons 20 move against the force of the compression springs 25 away from the clamping sleeves 14 to the lower end position thereby releasing the ball closure for the workpiece clamping pins 11 to pass. . When the clamping pin 11 is inserted into the respective clamping sleeve 14, the closure balls 19 are pushed outwards by the elevation 50 (FIG. 4) at the end side on the clamping member 11.

When the workpiece holder 2 is placed on the base 1, the clamping pins 11, which enter the conical entry section 17 of the clamping sleeves 14, provide for the pre-positioning of the workpiece holder 2 so that the linearly paired linear pairs of directional links J5, 10 interact. just the centering ruler 30 engages the groove 43 of the counterpart 10. As soon as the workpiece grip 2 is freely seated on the base 7 and then the compressed air supply through the channels 23 is interrupted, the compression springs 25 close the ball closure while pushing the pistons 20 against the clamping sleeves 14. wherein the respective annular collar 22 of the piston 20 pushes the shut-off balls 19 radially outward with their hollow conical members so that they engage the elevation 50 of the clamping pin 11. Later in this phase, the normally existing means for cleaning the stop surfaces 27,28 are put into operation. which are also known to us They allow the clamping process to be controlled by dynamic pressure measurement.

The clamping of the workpiece holder 2, which is mounted on the base 7, is carried out by compressing the underside of the piston 20 with compressed air supplied through the channels 24. The locking balls 19 are pushed with increased force into the interior and cause their intensified radial pressures against the conical annular surface. 51 (FIG. 4) of the clamping pins 11, pulling the clamping pins 11 into the clamping sleeve 4. In this process, the linear directional links 5 are oriented exactly to the respective directional links 10, where each wedge centering ruler 30 aligns into a corresponding groove 43 on the counterpart 11), whereby the wedge surfaces just assigned to each other come into contact with each other.

33, .44 (FIGS. 2 and 4). This alignment exists before the workpiece holder plate 7 reaches the annular stop surfaces 27 of the clamping sleeves 14 by friction. of the workpiece with the base 11 determined by the straight position of the workpiece grip in the X / Y plane and the position of the Z axis.

In the final stage of the clamping process, the centering rulers 30 are forcefully pressed into the grooves 43 of the counterparts 10, the central member 42 of which deflects under this force in the direction of the axis jZ. In the final state of the clamping process shown in FIG. 5, the workpiece holder plate 7 lies with its flat underside 9 under high pressure on the abutment surfaces 27 of the base 11. This, together with the relatively large surface contact, creates a force connection which can also absorb large transverse forces. As a result, the counterparts 10 serving as linear directional elements are relieved from transverse forces. In this way, a possible elongation or extension can be kept within the permissible limits. pressing the flexible rib 45 and the associated transverse displacement of the workpiece holder 2.

The clamp 2 of the workpiece described above can be removed without further support with the clamping pin 11 as a support, the clamping pins 11 have no and therefore do not require any particular fixture on the mattress platform because the fronts compensate for the gentle handling function.

Claims (14)

PATENT CLAIMS 1. Tool for position-defined clamping of a workpiece at a machine tool work station, with a stand (I) fixed at the machine tool work station and a workpiece clamp (2) that can be seated on it and firmly clamped thereon, 5,10,27,28) on the base and on the workpiece holder, which cooperate in pairs and align the workpiece holder in three mutually perpendicular coordinate axes (X, Y, Z) and angled on the base, and with the fixture (4,11) the clamping force of which holds the workpiece grip (2) firmly in the position determined by the directional links on the base (1), characterized by a combination of at least two of the following features: as pairs of directional positioning points in the coordinate axis (Z) parallel to the clamping force efficiency line, there are opposing stop surfaces (27,28) on the base and on the workpiece holder, while positioning in the two remaining coordinate axes (X, Y), for each coordinate axis, two linear pairs (5, 10) of the directional links are provided separately, having one wedge centering ruler (30) and one counterpart (40) with one aligned therewith. centering slot (43). the clamping fixture comprises a plurality of clamping members (4, 11) having one clamping pin (II) arranged on the workpiece clamp (2) and a clamping sleeve (4) arranged on the base (1). the workpiece holder (2) has, on the side (9), in the clamped state facing the base (1), a continuously flat surface which forms locally on this side stop surfaces (28) and on which linear directional members (10) are fixed on this side ) for determining the coordinate axes (X, Y, Z) as well as the clamping pins (11) of the clamping members (4, 11). The device according to claim 1, characterized in that the workpiece holder (2) is formed by a plate (7) with planar side faces (8,9). The device according to claim 2, characterized in that the plate (7) has through holes for receiving screws (21, 13) for fastening on this side of the linear directional links (10) and the clamping pins (11). The jig according to claim 3, characterized in that the fastening screws (12, 13) have a radial clearance in the respective through holes. Device according to claim 1, characterized in that the stop surfaces assigned to the base (1) are annular surfaces (27) spaced from the upper side of the base, which are each arranged concentrically to the clamping sleeve (4) and border immediately with space for movement of clamping pins (11) · A device according to claim 5, characterized in that the area of each annular surface (27) is several times greater than this from the cross-section of the clamping pin (11) at the most stressed location of its length extension. Device according to one of the preceding claims, characterized in that the base with a quadrangular base, four chucks (4) are centrally symmetrical (1) having a plate cover (3) in which they are arranged with a ball lock and arranged in four corners cover (3). 8. The device according to claim 1, characterized in that the clamping sleeve (14), the balls (19) and whose front sides of the base (1). of claim 5 and 7, characterized in that the clamping bushes have one which are provided with a closing protrusion over the cover (3) and form stop surfaces (27) Preparation according to one of the preceding claims, characterized in that the counterpart (10) of the linear pairs of directional links for determining the coordinate axes (X, Y, Z) cooperating with the wedge centering ruler (30) has a member (42) yielding. in the Z-axis direction, transverse to the Z-axis, on the other hand, rigid in which the centering slot (43) is located. A device according to claim 9, characterized in that the member (42) having the centering slot (43) is located in the center of the counterpart (10) between the two mounting strips (41) and with these mounting strips (41) is connected by bend-elastic ribs (45). A jig according to one of the preceding claims, characterized in that the wedge centering rulers (30) are prismatic, inserted into the grooves (31) and are fastened therein by means of screws (32), part of the long sides of the centering rulers (30). protruding from the grooves (31) form wedge surfaces (33). The jig according to claim 11, characterized in that the wedge angle of the wedge surfaces (33) of the centering rulers (30) on both sides is approximately 7 °. Preparation according to one of the preceding claims, characterized in that the linear pairs of directional members (5, 10) existing for determining the coordinate axes (X, Y, Z) are arranged in such a way between the stop faces (27, 28), that the axial cross is at least approximately in the center of the device. Device according to one of the preceding claims, characterized in that the directional links (5) formed by the wedge centering rulers (30) are fixed to the base (1) and the counterparts (10) having the centering groove (43) on the clip (2) workpiece.