LT5083B - Apparatus for clamping a work piece - Google Patents

Abstract

The apparatus for clamping a work piece in a well-defined position within the operating area of a machine tool comprises a support (1) and a work piece carrier (2) to be mounted on the support (1). Guiding elements (5, 10, 27, 28) are mounted on thework piece carrier (2) and cooperate to define the position of the work piece carrier (2) along three coordinate axes each running perpendicular to each other as well as with regard to the angular orientation. Fastening means (4, 11) fasten the workpiece carrier (2) on the support (1) in the position guided by the guiding elements. Each of fastening means has a securing chuck (4) on the support (1) and a fixing neck (11) on the work piece carrier (2). Pushing planes 27, 28) are provided opposite to each other and act as the guiding elements serving to determine a line position of acting forces.

Description

BACKGROUND OF THE INVENTION The present invention relates to workpiece clamping devices, in particular to positioning workpiece clamping in the working position of a machine tool. The machine is equipped with a fixed fixed workpiece in the working position and a workpiece holder that is fixed and firmly fixed to the machine. Further, guides are provided on the stand and on the workpiece bracket, which interact in pairs and orient the workpiece bracket on the workpiece in three perpendicular axes (X, Y, Z) and in angular directions. Finally, the clamping device according to the present invention comprises a fastening device, the clamping force of which holds the device firmly in place in the position of the guide elements.

This type of clamping device must, with the appropriate dimensions, be adapted to the possible attachment of larger and heavier parts and, when machined, can raise the resulting force without compromising positioning accuracy.

The development of larger clamping devices is based on the experience of the method of manufacturing smaller clamping devices. Known clamping device of the smaller style has two pairs of linear guide elements for an angular arrangement of position, fixed in the center circle of the anchorage, in a coordinate plane (Χ-Υ) formed by two coordinate axes (X, Y), and the operating line is disposed in the third coordinate axis. The working side edges of the wedge-shaped centering ruler and the working edges of the corresponding centering groove run radially to the Z axis.

Centering grooves through the recesses form a common plate that is flexible in the Z-axis direction. This plate is pressed into the workpiece holder with the centering ruler fixed to the fixture. The fastener consists of a fixed mounting cartridge having a ball sphere and protruding mounting necks protruding from the component holder, which are mounted on the mounting cartridge to press the component holder into the mounting cartridge. The solid positioning in the Z-axis is served by pins that are symmetrically pressed in the center of the workpiece bracket and which, on a permanent basis, face their rear sides in the support plane.

The clamping devices, in this embodiment, have a high ability to reproduce the position of the workpiece holder in relation to the constant and are reliable in fixing the workpieces for a sufficiently long position, particularly when the workpiece is subjected to negligible force during processing.

The load of such clamping devices is limited when particleboard is used, and their application is essentially limited to parts whose dimensions do not exceed those of the clamping devices themselves. When machining larger parts, the clamping device may develop a force that may be so great that the linear guides and fastener become overloaded and can no longer function in the desired manner and, above all, cannot maintain the required accuracy. Particularly critical are the torques that affect machining forces acting on the workpiece in the Z-axis, which are too large for the working sides, which are designed to provide firm positioning of the guide elements along the X- and Y-axes, and which induce pressure forces that compromise precise positioning accuracy. This pressure force allows the limits to be kept within limits, so larger parts need to be provided with larger clamping devices which have a stronger linear guiding element and a sufficiently large radial distance on the Z-axis. However, the known clamping device described herein is not suitable due to its manufacture, since it is only through enlarging its linear dimensions that it is adapted to the size of the workpieces. In particular, the central arrangement of the fastener is poor, whereby the corresponding clamping force is rendered inappropriate by the relatively high clamping force. The clamping device is of relatively poor shape and heavy and is therefore unsuitable for practical use. Further inconvenience arises from the positioning of the pins in the Z-axis. If these pins are located at a greater distance from the clamping force line of action, a deflection of the part holder is obtained, which compromises positioning accuracy. If the pins are placed closer to the clamping force line of action, a torque may occur, which is also undesirable in this case.

The object of the invention is to provide a better clamping device which can withstand higher loads and which does not have the disadvantages mentioned above. Therefore, we need to look at this object from a different angle. First and foremost is the fact that there is a need for a large number of manufactured clamping devices as well as a constant fit for them. On this basis, it was found to significantly reduce the cost of producing the part holder. Secondly, if the clamping device allows the user to use such a clamping device, another correspondingly perfect part holder can also be used.

The object of the present invention is to develop a clamping device based on the above-described state of the art, which is extremely obviously simple, inexpensive, with an easily adjustable component holder and which maintains the necessary positioning accuracy under all loadings.

The solution to this task is achieved by the fact that the clamping device initially selected in accordance with the present invention has at least two or three of the features set forth in the first claim of the invention.

According to this plan, the part holder can be made as a simple plate with flat parallel end planes, which, for example, must be provided solely with drilled holes, respectively, threaded holes for fixing the said linear guide elements, and with fixing nuts and nuts for details for mounting the bracket. This example of the invention is not only cheap; it also offers the possibility that another type of fixture holder can be adapted at a low cost for attaching the guide members and fastening necks to a defined permanent fixture.

Advantageously, the part-forming plate has through-hole drilling holes for securing the linear guides and fastening nuts by nuts, so that all fastening nuts are useful here. When the locking nuts have a radial clearance in the through-hole drill holes communicating therewith, this allows the locking necks to be positioned in an exact position, and in particular linear guides, so that the fixture with loosely mounted guide members and tie-downs is mounted and secured on the finished fixture. As a result, the latter adjusts on the plate to the attached part above the permanent on the associated parts. Correspondingly, the locking nuts may be tightened tightly on the said parts to lock in the occupied position. In this case, one can distinguish between the high accuracy of the production of said parts and the significant reduction in installation costs due to the above calibration methods. It can be further noted that the manufacturer of the characteristic fixture brackets can install the simpler guides and fasteners provided, achieving the required precision.

Ideally, the support plane for positioning relative to the Z-axis is made such that the support plates for the constant are removable from the top of the constant by circular planes that are respectively centrally disposed relative to the mounting chuck and directly restricting the mounting neck gap. It is possible to arrange the fixing force of the removable support planes as close as possible to the operating center, so that the bending force acting on the plate is minimized due to the fixing force. Further, the area of the support planes shall be as large as possible to achieve a sufficiently high frictional force to act against the displacement of the correspondingly interacting support planes resulting from the transverse force and to stop the displacement of the part holder relative to the constant.

Ideally, each annular surface area is several times larger than the cross-sectional area of the anchor neck at its most loaded location in its longitudinal extension. Under these circumstances, it is ensured that the position of the part holder inside the Χ / Υ planes, also under strong transverse force, does not change within the tolerance to the outside and does not overload the contacting pairs of elements.

For the solid arrangement of the coordinate axes (X, Y, Z), a solution known in principle 5 is provided, whereby each linear pair of guide elements has a wedge-shaped centering ruler and a fitting with a suitable centering groove. In this case, the preferred embodiment is where the wedge-centered ruler fitting has linear guides for positioning the coordinate axes (X, Y, Z) in the Z10 axis, which are inclined, transversely to the Z axis, in front of the protruding part. groove. Further, the centering groove portion is preferably located in the middle of the joint between the two fixing plates and is connected to these fixing plates via a flexible plastic bridge. Here, the fitting occupies a larger area where the centering neck, with respect to the space occupied, is justified by the presence of fasteners secured to the fitting having a centering groove for attaching the device to the article; here, the mounting necks as the mounting cartridges placed against each other on a permanent basis require less space.

Due to the location of the fasteners and linear guides near the edge of the clamping device, a smaller object can be obtained in the middle of the space for mounting the fastening device. The larger clamping device forms a bracket for the smaller clamping device and this clamping option allows the optional fixing of a larger or smaller piece.

An exemplary embodiment of the invention is illustrated in the accompanying drawings.

The drawings show:

FIG. 1 top view of the clamping device;

FIG. 2 cross-section through a constant of the clamping device;

FIG. 3, bottom view of clamping device detail holder;

FIG. 4 cross-section of the clamping device detail holder; and

FIG. 5 is a cross-sectional view of the clamping device according to FIG. 1 - 4 with fixture clamped in position 5 fixed to constant 5.

The clamping device shown consists of a stand (1) (Figs. 1 and 2) and a stand (2) (Figs. 3 and 4) which is mounted on a stand (1) and secured in a fixed position.

In the working position of the machine tool or in the measuring position, the fixed (1) has a flat body (3) with a square base plane. Here, a fastening device is provided having a plurality of fastening cartridges (4) with barrier spheres which according to Figs. 1 are symmetrically centered at four corners of the housing (3). In addition, on the upper side of the housing (3) there are four linear guide elements (5) arranged in a cross relative to each other between the two adjacent mounting cartridges (4). In the center of the housing (3) there is a free space (a circle (6) depicted in dotted line in Fig. 1) in which it is known to accommodate a constant of a smaller clamping device, for example as in the initially described example. A means for fixing a constant in a working position is known and not shown here.

The part holder (2), which is mounted and secured on the stand (1), is designed as a plate (7) with flat parallel end planes (8) and (9), and the workpiece is secured in a known manner on the upper plane (8). Necessary means, such as threaded holes provided in the plate (7), are not shown in the drawings. The lower plane (9), which in the fixed state of the part holder (2) is directed towards the constant (1), forms a continuous smooth upper plane on which the linear elements interacting with the guide elements (5) on the constant (1) (10) and the fastening necks (11) of the mounting device are secured by means of nuts (12) and, respectively, (13). The fastening nuts (12, 13) are provided with through-drilled bore holes in which the fastening nuts have radial gaps.

Each mounting bracket (4) provided on the stand (1) has a mounting sleeve (14) 5 which is secured by a nut (15) on the housing (3) of the stand (1). The cavity (16) in the inlet segment (17) of the sleeve (14) is tapered outwards. Connected to this entrance segment (17) is a ring-shaped segment (18) provided with a spherical constraint formed by a crown of radially movable barrier balls (19). The engagement of the shutter balls (19) in the clamping process takes place through a press environment on both sides of the pressed piston (20) disposed in the cylindrical space (21) of the housing (3) and the annular sleeve (22) surrounding the ring of the mounting sleeve (14). shape segment (18). The slightly tapered annular sleeve (22) is more extensively tapered on its inner surface outwardly at its end surface, and this hollow conical portion of the annular sleeve (22) interacts with spherical barrier spheres (19) in a known manner. (23) and (24) are marked feed openings for supplying a pressurized environment to the upper, respectively, lower side of the piston (20). The supply pistons (20) are arranged beneath a certain number of pressure springs (25), which rest on a cylindrical space (21) defining from below the cover plate (26). The flanges (27) of all bushings (14) are disposed above the upper side of the housing (3) in a raised plane and form ring-shaped support planes on which the lower plane (9) of the plate (7) of the part holder (2) rests. Said planar areas (28) on the plate (7) FIG. 3 are marked with strikethroughs. These pairwise interacting support plates (27) and (28) form pairs of guide members for securing the position of the part holder (2) in the Z axis. The center (1) may have a center, which in a known manner enables the support planes (27, 28) to be neatly formed. For this purpose, air pressure channels are provided which are included in the support plate (27) of the bushing (14).

The linear guide elements (5) provided on the riser (1) according to FIG. 1 and is a prismatic centering ruler (30) which is housed in a groove (31) of the housing (3) and secured therein by nuts (32). The longitudinal planes of the projecting centering ruler (30) form wedge planes (33) which are wedged in relation to each other in profile, and the angle of the wedge on each side is about 7 °. The fitting of the centering ruler (30) is not critical with respect to its exact position, whereby, respectively, the two wedge planes lying in line with one another can co-locate two diametrically opposed centering rulers more accurately.

Each connecting member interacting with the linear guide member (5) of the constant (1) with a centering groove defined by the guide member (10) of the component holder (2) is in accordance with FIG. 3 and 4 profile plate (40) with a central portion (42) between the two fasteners (41) having a centering groove (43) with wedge-shaped lateral planes (44), with the angle of the wedge again in both. The middle portion (42) is connected to the fastening plate (41) through a curved elastic bridge (45) and thus forms a flexible but transversely spaced but rigid portion in the Z-axis. Each fastening neck (11) interacting with the mounting cartridge (14) has a configuration according to FIG. 4, at its free end, a thickening (50), which at its rear is bounded by an annular plane (51) and barrier balls (19) of the mounting cartridge (14). FIG. 2 represents the constant (1) in the static state. The piston (20) of the mounting cartridge (4) is depressurised, exerted only by the pressure springs which hold the piston (20) against the mounting sleeve (14). In this position of the piston, the spherical barrier balls (19) are in the extreme closed position and, in addition, a known means prevents the barrier balls (19) from falling from their position into the cavity (16) of the mounting sleeve (14).

In the initial position of the stand (1) for receiving the component holder, the upper side of the piston (20) through the inlet channel (23) is exposed to a pressurizing medium such as compressed air such that the pistons (20) move against the force of pressure springs (25) ) to the lower end position, thereby releasing the sphere closure to accommodate the attachment neck (11) of the component holder (2). When the retaining neck (11) enters the respective retaining sleeve (14), the locking balls (19) are pushed radially to the side by the rear thickening (50) of the retaining neck (11) (Fig. 4).

By positioning the part holder (2) on the constant (1), it is attempted to position the attachment necks (11) of the part holder (2) entering the conical entry segment (17) of the mounting sleeve 5 so that the pairs of linear guide elements (5,10) interact ) to engage with each other, furthermore, respectively, the centering ruler (30) enters into the groove (43) of the fitting (10). As soon as the part holder (2) is freely placed on the stand (1) and as a result the supply of compressed air through the channels (23) is interrupted, the pressure springs close the spherical blocker and simultaneously press the piston (20) against the mounting sleeve (14), furthermore, the respective annular sleeve (22) of the piston (20) with its hollow conical portion pushes the locking balls (19) radially outwards so that they catch the thickening (50) of the fastening neck (11). Later in this phase, the normally existing middle of the thrust planes (27, 28) is cleanly blown into the action zone and also controls the fastening process in a known manner by measuring the dynamic pressure.

The clamping of the part holder (2) placed on the constant (1) according to Figs. 5 proceeds through an interruption of compressed air discharged through the lower half of the piston (20) through the channel (24). The locking balls (19) are simultaneously pushed radially inwardly by increased force and act through their enhanced radial pressure against the conical annular plane (51) of the securing necks (11) (Fig. 4) by engaging the securing necks into the securing cartridge (4). According to this process, the linear guide members (5) are aligned exactly on their respective guide members (10), so that each wedge-shaped centering ruler (30) hits the corresponding groove (43) of the joint member (10), , overlapped by wedge planes (33, 44) respectively (Figs. 2 and 4). This alignment occurs before the plate (7) of the component holder (2) rests, by frictional closure, on the annular displacement plane (27) of the mounting sleeve (14). In this way, the position of the undistorted angular relationship of the part holder (2) in the Χ / ir plane and the position of the Z axis before the final connection of the part holder (2) to the constant (1) is determined.

In the final phase of the fastening process, the centering ruler (30) is firmly pressed into the groove (43) of the fitting (10), the middle part (42) of which is inclined in the Z axis due to the action of the force. FIG. In the final position of the fastening process shown in Fig. 5, the plate (7) of the component holder (2) with its smooth lower side (9) is positioned under high pressure on the constant displacement plane (27). In combination with a relatively large area contact, this provides a closing force that is also capable of absorbing a large transverse force. Therefore, the load of transverse force acting on them is further reduced from the fittings (10) which serve as linear guides. In this way, a possible extension of the flexibly elastic bridge (45) is obtained, respectively, flattening and the associated transverse displacement of the part holder (2) within the permissible limits.

The clip holder (2) of the clamping device described above allows the fastening necks (11) to be openly oriented on a support plane as a support; here the transverse ends of the fastening necks (11) have no guide function and therefore do not require special protection.

Claims (14)

Definition of the Invention 1. A device for clamping a workpiece by positioning it in the working position of a machine tool having a fixed fixed position (1) and A part holder (2) disposed on and fixed to the stand (1), further comprising guide members (5, 10, 27, 28) on the stand and the part holder which interact in pairs and orient the part holder on the stand three the other perpendicular to the coordinate axes (Χ, Υ, Ζ), both in the angular directions and in the attachment device (4, 11), which has a clamping force 10 secures the part holder (2) by means of the guide elements in a fixed position on the constant (1), characterized by a combination of at least two of the following features: - one position is provided as a pair of guide elements for positioning the clamping force acting parallel to the coordinate axis (Z) In the positioning with respect to the other two coordinates (X, Y), two pairs of guide members (5, 10), which are wedge-shaped, are provided separately for each axis in the positioning of the 15 forward displacement planes (27, 28) a centering ruler (30) and a fitting (40) with a corresponding centering groove (43); 20 - the fastening device comprises a plurality of fastening means (4, 11), each having a fastening neck (11) disposed on the component holder (2) and a fastening cartridge (4) disposed on the constant (1); - the part holder (2), when secured, has a continuous, flat top plane on the recessed side (9) forming a lateral side 25, and on which lateral linear guides (10) are fixed for determining the coordinate axes (Χ, Υ, Ζ) as well as the fixing necks (11) of the fixing means (4,11). Device according to claim 1, characterized in that the parts The bracket (2) 30 is a plate (7) having parallel end planes (8, 9). 3. Apparatus according to claim 2, characterized in that the plate (7) has bore holes for inserting nuts (12, 13) securing lateral linear guide elements (10) and fastening necks (11). 4. Device according to claim 3, characterized in that the fastening nuts (12,13) have a radial gap in the respective boreholes. 10th 5. A device according to claim 1, characterized in that in the displacement planes assigned to the constant (1), annular planes (27) are formed from the upper side of the constant which are respectively centrally disposed about the mounting cartridge (4) and directly adjacent to the mounting neck (11). between the movements. 6. A device according to claim 5, characterized in that the area of each annular plane (27) is several times larger than the cross-sectional area of the fastening neck (11) at its most loaded location in its longitudinal extension. 20th Device according to one of the preceding claims 1 to 6, characterized in that the constant (1) has a flat body (3) with a rectangular base surface, in which four fixing cartridges (4) arranged symmetrically in relation to the center are fixed by a ball bar. at the corners of the housing (3). 8. A device as claimed in claims 5 and 7, characterized in that the mounting cartridge has one mounting sleeve (14) with provided retaining balls (19) which protrude above the housing (3) and whose front side forms the displacement planes (1) of the constant (1). 27). Device according to one of Claims 1 to 8, characterized in that the coupling part (10) interacting with the wedge-shaped centering ruler (30) has a pair of linear guide elements serving the coordinate axes (X, Y, Z). for adjustment with a relatively rigid portion (42), in the flexible direction of the Z-axis containing the centering groove (43). Device according to Claim 9, characterized in that the part (42) having a centering groove (43) is located in the middle of the joint (10) between the two fastening ribs (41) and is connected to these fastening plates via a flexible elastic bridge (45). 41). Device according to one of Claims 1 to 10, characterized in that the wedge-shaped centering ruler (30) is prismatic, inserted into the groove (31) and secured therewith by means of the nuts (32). 31) a centering ruler (30) formed in the projecting portion 15 sides of the wedge plane (33). 12. A device according to claim 11, characterized in that the wedge angle of the wedge planes (33) of the centering ruler (30) is about 7 °. Device according to one of the preceding claims 1 to 12, characterized in that for the determination of the coordinate axes (X, Y, Z) there exist a pair of linear guide elements (5, 10) between the displacement planes (27, 28) are arranged such that the intersection of the axes is at least approximate 25 in the middle of the device plane. Device according to one of the preceding claims 1 to 13, characterized in that the guide elements (5) and the centering groove (43) are formed on the constant (1) through a wedge-shaped centering ruler (30). The fitting 30 (10) is secured to the piece holder (2).