SI21177A - Workpiece clamping device - Google Patents

Abstract

A clamping device comprises a basic assembly (1) and a workpiece holder (2) attachable to it, where aligning elements (5, 10, 27, 28) acting in pairs are distributed and are aligning the workpiece holder (2) on the basic assembly (1) along three mutually perpendicular coordinate axes and at proper angles. Clamping elements (4, 11) are grasping the workpiece holder (2) with their clamping force on the basic assembly (1) in the position determined by the aligning elements. Each clamping element has a clamping head (4) on the basic assembly (1) and a clamping male (11) on the workpiece holder (2). Stopping faces (27, 28) located mutually one against another are available as aligning elements for fixing the position along the coordinate axis (Z) parallel to the direction of the clamping force action. To make the workpiece holder (2) structure as simple as possible and its manufacture cost-effective, it has an overall even surface in the clamped state on the side (9) turned against the basic assembly (1), which is creating stopping faces (28) lying on this side for respective areas and where aligning elements (10) lying on this side for fixing the coordinate axes and clamping males (11) are attached.

Description

Preparation for mounting the workpiece

The present invention relates to a clamping device, in particular a positional (positional) defined clamping of a workpiece at the workpiece of the machine, the device comprising a base assembly which is fixed at the workplace of the machine tool and a workpiece carrier to be mounted on said base assembly , where it clamps. Furthermore, the alignment (directional) elements acting in pairs are provided on the base assembly and the workpiece carrier, and the workpiece carrier is aligned in three rectangular coordinate axes (X, Y, Z) with respect to the base assembly (X, Y, Z) and rotated correctly. The clamping device of the invention lastly comprises a clamping device, the clamping force of which holds the workpiece carrier on the base assembly in a position as determined by the alignment members.

Clamping devices of this type should, if properly dimensioned, be suitable for clamping relatively large and heavy workpieces and, moreover, be able to withstand the forces involved in cutting work without affecting the desired positioning accuracy.

The development of larger clamping devices is based on the experience gained from smaller clamping devices. In one of the known smaller clamping devices, two pairs of linear alignment elements for determining the correct rotation of the coordinate planes (Χ-Υ) defined over a two coordinate axes (X, Y) are arranged in a circle around the central clamping device, the line of operation of the clamping device it lies in the third coordinate axis (Z) and the working flanks of the wedge centering rulers and the working edges of the corresponding centering grooves extend radially to the Z axis. The center grooves are formed by cutouts in the common plate, which is in the direction of the Z axis. This plate is located on the workpiece carrier, while the centers of the ruler are hidden on the base assembly. The clamping device consists of a clamping head with a ball retainer in the base assembly and a clamping plug that protrudes from the workpiece carrier and is inserted into the clamping head on the base assembly for clamping the workpiece carrier. For fixing the position in the Z axis, centrally symmetrically arranged side arms are used on the workpiece carrier, which with their front face is applied to the support surfaces on the base assembly.

Clamping devices of such an embodiment are characterized by the required repeatability of the position of the workpiece carrier relative to the base assembly, and it has long been the case since they have been carried out, especially when negligible forces are exerted on the workpiece, such as in the case of electro-erosion treatment. for positionally defined workpiece clamping.

When cutting by clipping, the load capacity of such clamping devices limits their scope mainly to workpieces whose dimensions are no larger than the size of the clamping device itself. When machining larger workpieces, forces may occur on the clamping device which, under the circumstances, are such that the linear alignment elements and the clamping device are overloaded and their functions can no longer be fulfilled in the desired manner and, above all, no longer with the required precision. Particularly critical are the torques exerted by the machining forces on the workpiece carrier with respect to the Z axis, which may produce excessively large compressive force forces on the positioning points of the X and Y axes of the respective pairs of alignment elements. These compressive forces can only be kept within the permissible limits by providing for larger workpieces to be provided with larger clamping devices in which the said two linear alignment elements are suitably stronger and radially spaced from the Z axis. As regards the structure of the known clamping device described above, it is not suitable to be adapted to the size of the intended workpiece by simple linear enlargement of its dimensions. In particular, the central placement of the coupling device would prove inappropriate, since a single coupling body would become appropriately large due to the greater coupling force. The clamping device would thus become rather shapeless and difficult and therefore unsuitable for practical use. A further problem exists with the arrangement of the jibs for position fixation in the Z axis. If the jibs are at a greater distance from the coupling force line, then the workpiece carrier bending, which impairs positioning accuracy, must be considered. On the other hand, when positioning the pistons close to the coupling force, there are twisting moments that are undesirable for the same reasons.

The object of the invention is, in view of the aforementioned drawbacks, to create an improved clamping device suitable for heavy loads. Some further aspects should be taken into account. First of all - given the fact that significantly more workpiece carriers are required in a particular workpiece than the basic workpieces, it is increasingly necessary to take into account that the cost share for the workpiece carrier is decisively reduced. Furthermore, the supplier of such clamping devices is supposed to enable the supplier of the clamping devices to be able to use the workpiece supports from their own development program.

The task underlying this invention is, after all, to create a clamping device of a kind that is constructed in such a way that it is simple, cost effective and flexible, especially with respect to the workpiece carrier, and ensures that the necessary precision is maintained at all emergent loads. positioning.

The solution to this problem is obtained if the aforementioned clamping device according to the invention has at least two of the three claimed characteristics in claim 1.

With this design, the workpiece carrier can be made as a simple piano board with parallel work surfaces, which must be equipped, for example, with holes or holes only. threaded holes for securing said linear alignment elements and clamping plugs and for fixing the workpiece by means of screws. Not only is this design extremely cost-effective, it also offers the ability to adapt the workpiece carrier of a third-party machine without much difficulty to the prerequisites for installing alignment elements and clamping plugs with respect to a particular base assembly.

Preferably, the workpiece carrier plate has through holes to be inserted into the screws to secure the side (i.e. workpiece-bound) linear alignment elements and clamping plugs so that all the fastening screws can be accessed from the side facing away. from the parts we tighten. However, if the mounting screws in the respective through holes have radial clearance, the exact position of the coupling plugs and, in particular, the linear alignment elements can be fixed by mounting the workpiece carrier with the freely mounted aligned elements and the coupling plugs on the finished base assembly. . This way, the parts that need to be fixed on the board are aligned with the antibodies on the base assembly. The fastening screws are then tightened to secure the position occupied by the aforementioned parts. In this way, the bearings for said parts, which need to be manufactured with great precision, are eliminated and the assembly method is significantly reduced. Furthermore, it also makes it easier for the manufacturer of the workpiece carrier to mount the supplied alignment elements and clamping plugs with the required precision.

As regards the Z-axis positioning support plates, there is a preferred embodiment in that the basic assembly of the adapted support surfaces are offset annular surfaces from the top of the basic assembly, which are arranged concentrically with the clamping head each time and adjacent directly to the movement space these for the coupling plug. This is to ensure that the support surfaces that receive the clamping force are located as close as possible to the center of action of the clamping force, so that the bending moments acting through the clamping forces on the plate are as small as possible. Furthermore, the planar dimension of the support surfaces should be as large as possible in order to obtain sufficiently large friction forces which, under the influence of transverse forces, counteract the reciprocal movement of the respective support surfaces, thereby preventing the lateral movement of the workpiece carrier relative to the base assembly.

Preferably, the planar dimension of each annular surface is many times greater than the planar dimension of the cross-section of the clamping plug at the location of its longitudinal dimension, which is most loaded. Under these circumstances, it is guaranteed that the position of the workpiece carrier inside the Χ / ravn plane does not change beyond the tolerance limit even under high load due to transverse forces, and that the respective alignment element pairs are not overloaded.

Regarding the fixation of the X, Y, Z coordinate axes, a principle known in principle is foreseen, in which each of the two linear alignment elements has a wedge-centered ruler and a counterbalance with a nearly centered groove. In the present example, we recommend a structure in which the counterpart of the two linear alignment elements for fixing the X, Y, Z coordinate axes in the Z axis direction extends one, and the rigid portion transposed on the Z axis, with the wedge centered ruler, wherein the centering groove portion is located in the middle of the antibody between the two fixing slats and is connected to these fixing slats via flexibly elastic bridges. Since antibodies occupy more planar space than center plugs, in view of the need for loosening of the coupling bodies, it may be prudent to attach the centrally-grooved antibodies to the workpiece carrier, since coupling plugs require less planar space than opposite coupling heads. .

By positioning the clamping bodies and linear alignment elements near the circumference of the clamping device, it is possible to leave a blank space in the middle of the clamping device for the installation of a smaller clamping device. The larger clamping device thus forms a support for the smaller clamping device and can be used with larger or smaller workpieces, if necessary.

On the basis of the accompanying drawings, an embodiment of the invention will now be described in more detail below. The sketches show:

FIG. 1 basic assembly of the clamping device in the top view;

FIG. 2 is a basic cross-sectional assembly assembly;

FIG. 3 shows the workpiece carrier of the clamping device in the bottom view;

FIG. 4 is a cross-sectional view of the workpiece holder of the clamping device; and

FIG. 5 illustrates the clamping arrangement according to FIGS. 1 to FIG. 4 with workpiece carrier positioned and fixed on base assembly.

The presented clamping device consists of a base assembly 1 (FIG. 1 and FIG. 2) and a workpiece carrier 2 (FIG. 3 and FIG. 4), which is mounted on the base assembly 1 and fixed thereon in a defined position.

The base assembly 1, which is fixed at the workplace of the machine tool or, optionally, also the measuring station, has a flat housing of 3 square feet. It is provided with a clamping device comprising four clamping heads 4 with each ball retainer according to FIG. 1 arranged centrally symmetrically in the four corners of the housing 3. On the upper side of the housing 3 there are further dashed linear alignment elements 5 arranged crosswise with respect to each other, each with two adjacent clamping heads 4. In the middle of the housing 3 there is an empty space (at Fig. 1 is indicated by the dotted dotted circle 6), which can accept in a known manner the basic assembly of a smaller clamping device, such as the one described above. The fixings of the base assembly 1 in the workplace are known as such and are not represented here.

In the case of the workpiece 1, the workpiece mountable and fixed to it by the workpiece is a plate 7 with planar parallel working surfaces 8 and 9, with the workpiece to be machined attached to the upper surface 8 in a known manner. The means required for this purpose, such as the threaded holes provided in panel 7, are not shown in the drawings. In the lower surface 9, which faces the base assembly 1 in the mounted state of the workpiece carrier 2, it is a completely flat surface where two-sided linear alignment elements 10 and s cooperate with the alignment elements 5 of the base assembly 1 in pairs. by means of screws 13 clamping plugs 11 clamping device. The mounting screws 12, 13 are provided through holes where the fixing screws have radial clearance.

Each of the base assembly 1 provided with a clamping head 4 comprises a clamping sleeve 14 which is secured in the recessed cutout on the housing 3 of the base assembly 1 by screws 15 and has a hollow space 16 for receiving the clamping plug 11. The hollow space 16 is in the entry section 17 of the clamping unit. cone 14 extends conically outwards. Attached to this inlet section 17 is an annular section 18 which is provided with a crown of radially movable retaining beads 19 that form a ball retainer. The clamping ball 19 moves with the pressure medium to a bilaterally loaded piston 20 disposed in the cylinder space 21 in the housing 3 and with the annular attachment 22 encloses the annular section 18 of the coupling sleeve 14. The slightly conical inner surface of the annular attachment 22 is in its end region at outwardly more conically expanded, with this funnel portion of the annular attachment 22 interacting in a known manner with the retaining beads 19 of the ball retainer. To the upper or. the lower sides of the piston 20 are guided by the inlets 23 and 24 for the pressure medium. The piston 20 is further loaded by the force of the compression springs 25 which are mounted on the end plate 26 which closes the space 21 from below.

The upper front faces 27 of the clamping sleeves 14 lie in a plane that is offset from the upper surface of the housing 3 and form annular abutments, on which the workpiece plate 7 of the workpiece carrier 2 rests with its lower surface 9. The respective plan areas 28 of panel 7 are shown in FIG. 3 indicated by dotted shading. These two and two cooperating support surfaces 27 and 28, respectively, form pairs of alignment members for fixing the position of the workpiece carrier 2 in the Z axis.

On base assembly 1, there may be means which in a known manner can be used to clean the support surfaces 27, 28 prior to their removal. For this purpose, air ducts may be provided having an outlet on the front sides of the 27 coupling sleeves 14.

In the basic assembly 1, the alignment elements 5 provided are as shown in FIG. 1 and FIG. 2 for prismatic center rulers 30, which are inserted into the grooves 31 of the housing 3 and are fastened therein by screws 32. The outer longitudinal sides of the center rulers 30 are inclined surfaces 33 which extend in a wedge-shaped profile with the inclination angle on each side. it is about 7 °. The mounting of the centering rulers 30 in terms of their exact position is not critical, since the respective line-aligned wedge surfaces 33 of the two diametrically opposite one another of the centering rulers 30, after the rulers are installed, can be jointly cut to a precise dimension.

Each participant with a linear alignment element 5 of the base assembly 1, as the 'centered groove antibody', the named alignment element 10 of the workpiece carrier 2 is shown in FIG. 3 and FIG. 4 is a profiled plate 40 with a median portion 42 between the fasteners 41 having a center groove 43 with a wedge-shaped lateral face plate 44, with the wedge angle again about 7 ° on each side. The middle portion 42 is connected to the mounting brackets 41 via bending elastic bridges 45 and thus forms a rigid portion in the direction of the Z axis and transversely to the Z axis. Each of the clamping head 14 of the cooperating clamping plugs 11 has, according to FIG. 4 at its free end, the buzzer 50, which is bounded at its rear by a conical annular surface 51, where the retaining beads 19 of the clamping head

14.

In the FIG. 2 is a representation of the base station 1 in idle state. The pistons 20 of the clamping heads 4 are loaded because there is no compressive load, only the compression springs 25 which press the pistons 20 to the clamping sleeve 14. In this position of the pistons, the retaining balls 19 of the ball retainer are in the extreme restraint position, where inherently unknown means are present here. the retaining beads 19 protect against falling out of their beds into the hollow space 16 of the coupling sleeve 14.

In order to prepare the base assembly 1 to receive the workpiece carrier 2, the upper side of the pistons 20 is pressurized through the inlet channels 23, such as compressed air, and then the pistons 20 are moved against the force of the pressure springs 25 away from the coupling sleeves 14 to the lower end position, and thereby releasing the ball retainer for the passage of the coupling plugs 11 of the workpiece carrier 2. When the clamping plug 11 is inserted into the clamping sleeve 14 in question, the locating bead 50 (FIG. 4) of the retaining ball 19 pushes radially out at the head of the clamping plug 11.

When the workpiece carrier 2 is mounted on the base assembly 1, the inlet clamping plugs 11 provide a pre-positioning of the workpiece carrier 2 in the conical inlet section 17 of the coupling sleeves, so that two and two cooperating pairs of alignment elements 5.10 are recovered from each other, centering the ruler each time. 30 is harvested by the slots 43 of the antibody 10. When the workpiece carrier 2 is freely attached to the base assembly 1 and then interrupted the supply of compressed air through the channels 23, the pressure springs 25 by pushing the pistons 20 against the clamping sleeves 14, closing the ball retainer, in each case, the annular nozzle 22 of the piston 20 moves radially inward with its funnel portion of the retaining ball 19, so that they are grabbed from the back by the clamp 50 of the clamping plug 11. At the latest, at this stage, the normally available cleaning agents for the backrests 27, 28 are included. in a known manner, through bordering, they also allow the coupling operation to be controlled.

Tighten the workpiece carrier 2 mounted on the base assembly 1 according to FIG. 5 through compression of the underside of the piston 20 s through the ducts 24 supplied with compressed air. The retaining beads 19 are thereby radially inwardly forced into the retaining ball 19 and then by their increased radial pressure, they are tightened to the clamping head 11 (Fig. 4) of the clamping plugs 11 into the clamping head 4. In this step, the linear alignment elements 5, by aligning each wedge-centered ruler 30 with the respective groove 43 of the antibody 10, are aligned precisely with the corresponding alignment elements 10, each time contacting the mutually engaging sloping surfaces 33, 44 (FIG. 2 and SL). 4). This pick-up occurs before the workpiece carrier carrier plate 7 is then locked in place on the annular support surfaces of the 27 coupling sleeves.

14. Thus, from the point of view of rotation, the position of the workpiece carrier in the plane Χ / Υ and the position

-1010 Z axis fixed already before the workpiece carrier 2 is finally connected to the base assembly

1.

In the final clamping phase, the centers of the ruler 30 are strongly pressed into the grooves 43 towards the parts 10, the middle portion 42 of which, under the effect of this force, bends in the direction of the Z axis. In the final coupling state, as shown in FIG. 5, the workpiece carrier plate 7 with its flat underside 9 under high pressure rests on the support surface 27 of the base assembly. This, together with relatively large-scale contact, results in a silo, which can also withstand large transverse forces. As a result, the transmittance of the transverse forces is essentially spared to the antibodies 10, which serve as linear alignment elements. In this way, otherwise stretching or stretching is possible. shrinkage of bending bridges 45 and the associated transverse displacement of the workpiece carrier 2 to keep within permissible limits.

The carrier 2 of the workpiece of the described clamping device can be further removed with the clamping plugs 11 as legs to the mounting surface, since the front sides of the clamping plugs 11 have no alignment function and therefore no special care is required.

Claims (14)

Patent claims A device for positionally defined mounting of a workpiece at the workpiece workstation, with a base assembly (1) fixed at the workpiece workstation and a workpiece holder (2) mounted on said workpiece assembly where it is clamped , in addition, the alignment elements (5, 10, 27, 28) provided in pairs and the workpiece carrier with respect to the basic assembly are aligned in three coordinate axes arranged perpendicularly to each other with the base assembly and the workpiece carrier (X, Y, Z). and properly rotated, and with a clamping device (4, 11), the clamping force of which holds the workpiece carrier (2) on the base assembly (1) in a position determined by the alignment members, characterized by the combination of at least two of the following characteristics: • as two pairs of alignment elements for position fixing in relation to the line of action of the coupling force, parallel coordinate axes (Z) are available on the base assembly and the workpiece carrier opposite to each other, the supporting surfaces (27, 28), while for position fixing in of two other coordinate axes (X, Y), for each coordinate axis, are provided for two pairs of linear alignment elements (5, 10) having one wedge-centered ruler (30) and one antibody (40) with a ruler-centered groove (43) ); The clamping device comprises clamping bodies (4, 11) having one clamping plug (11) and one clamping head (4) arranged on the workpiece carrier (2), and one clamping head (4) arranged on the base assembly (1); and • the workpiece carrier (2) has a flat surface, which forms the two-sided abutment surfaces (28) on the side, which is in the engaged state facing the base assembly (1), and on which the lateral linear alignment elements (10) are attached. for fixing the coordinate axes (X, Y, Z) and clamping plugs (11) of the clamping bodies (4, 11). Device according to claim 1, characterized in that the workpiece carrier (2) is formed by a plate (7) with planar parallel working surfaces (8, 9). -1212 Device according to Claim 2, characterized in that the plate (7) has through holes to be inserted into the screws (12, 13) for attaching the toe linear alignment elements (10) and the clamping plugs (11). Device according to claim 3, characterized in that the mounting screws (12, 13) have radial clearance in the respective through holes. Apparatus according to Claim 1, characterized in that the base assembly (1) of the adjoining support surfaces is disposed annularly from the top of the base assembly (27), which are in each case arranged concentrically with the clamping head (4) and directly adjacent to the movement space of the clamping plug (11). Device according to claim 5, characterized in that the planar dimension of each annular surface (27) is several times greater than the planar dimension of the cross-section of the coupling plug (11) at the point where it is most loaded. Device according to one of the preceding claims, characterized in that the base assembly (1) has a flat housing (3) of a quadrangular floor plan, with four clamping heads (4) with ball attachment and centrally symmetrically arranged in four corners of the housing (3). ). Device according to Claims 5 and 7, characterized in that the clamping heads, each with retaining beads (19), are provided with a clamping sleeve (14) projecting above the housing (3) and the front side of which forms the support surface (27) of the base assembly (1). Device according to one of the preceding claims, characterized in that, with the wedge-centered ruler (30), the counterpart (10) of the pairs of linear alignment elements for fixing the coordinate axes (X, Y, Z) in the direction of the Z axis is provided with one transverse on the Z axis, the rigid part (42) where the centering groove (43) is located. -1313 Device according to claim 9, characterized in that the part (42) having the centering groove (43) is located in the middle of the antibody (10) between the fixing slats (41) and is connected to the latter by bending elastic bridges (45). Device according to one of the preceding claims, characterized in that the wedge-shaped centering elements (30) have a prismatic design and are inserted into the grooves (31) and secured therein by means of screws (32), having from the grooves (31) projecting out of the longitudinal sides of the centering rulers (30) of the oblique surface (33). Device according to Claim 11, characterized in that the angle of the wedge of the oblique surfaces (33) of the centering rulers (30) is approximately 7 ° on both sides. Apparatus according to one of the preceding claims, characterized in that the coordinate axes (X, Y, Z) of the prepared pair of linear alignment elements (5, 10) are arranged so as to be arranged between the support surfaces (27, 28) such that the intersection of the axes is located at least approximately in the middle of the system plot of the preparation. Device according to one of the preceding claims, characterized in that the alignment elements (5) formed by the wedge-centered rulers (30) attached to the base assembly (1) are antibodies (10) having a centering groove (43). ) on the workpiece carrier (2).