CARRIER DEVICE AND METHOD FOR OPERATING A CARRIER DEVICE

Description

[0001] The present invention relates to a support device for a metal-cutting processing machine having a base body and at least one clamping device arranged on the base body for fastening a processing unit, wherein the at least one clamping device and / or the base body is designed to be rotatable along an axis of rotation running in a first direction, wherein the at least one clamping device has a clamping element arrangement which is designed to at least partially engage the processing unit in a fastening state by moving clamping elements in a direction running perpendicular to the axis of rotation.

[0002] Such support devices can fundamentally be designed in different ways and used for various purposes within a metal-cutting machine. For example, the machining unit may be a tool, such as a drill or a milling cutter, which is attached to the base body via at least one clamping device. In such a case, the clamping device itself is typically designed to be rotatable, thus enabling metal-cutting machining as a result of the rotation of the tool.

[0003] Alternatively, the machining unit can also be a workpiece that engages in the clamping device either directly or via an additional pallet and is then fixed to the base body by means of the latter. The use of a pallet as a machining unit is particularly useful in this context, since the clamping element arrangement gives the clamping device a predetermined clamping geometry, which usually requires a corresponding counterpart on the machining unit. The clamping element arrangement is designed in such a way that it has several clamping elements arranged along a circumference, which would move radially inward during fixation and then engage in a section of the machining unit, thereby fixing it.Thus, the machining unit requires a bolt-shaped section that can be inserted into the opening between the clamping elements and that has a recess or circumferential groove in the bolt-shaped section, into which the clamping elements then engage when fastened. Such a design is significantly easier to implement with prefabricated pallets than directly on the workpiece, so that the workpiece is usually first clamped on a pallet and then fixed to the base body together with the pallet via at least one clamping device. Within the scope of the invention, with such a design, the pallet together with the workpiece to be machined forms the machining unit.

[0004] Furthermore, in such a case, it is usually not the clamping device itself but rather the base body that is designed to rotate, while the clamping device is fixed in the base body in a non-rotatable manner. Such a design is therefore also referred to as a rotary table, whereby the workpiece can be positioned within the metal-cutting machine by rotating the base body.

[0005] Such support devices are generally known from the prior art. For example, EP 2 301 712 B1 describes a metal-cutting processing machine with a workpiece carrier and a tool holder, wherein both the workpiece carrier and the tool holder form a support device to which either a tool or a workpiece can be attached in the sense of a processing unit. In this context, the tool carrier is designed as a rotary-swivel table in which not only the workpiece itself can be rotated about a rotational axis. Rather, the base body can also be pivoted relative to a horizontal axis, which allows the positioning of the workpiece to be influenced to a greater extent.

[0006] Such carrier devices are also sold, for example, by CyTec Zylindertechnik GmbH under the product name CyTurn. These are so-called rotary tables, which are designed either as classic rotary tables or as rotary-tilting tables. Accordingly, these rotary tables can be rotated along a rotary axis, with a total of four clamping devices arranged one behind the other in the circumferential direction. Such clamping devices are also referred to as zero-point clamping systems and are used to fix a workpiece or a pallet with a workpiece. The clamping devices are usually driven hydraulically or pneumatically, whereby the principle of such a clamping device is described, for example, in EP 0 219 594 B1.Accordingly, a bolt is inserted into a receiving opening of the clamping device and then a sliding sleeve is moved parallel to the bolt by applying pressure, whereby clamping elements are simultaneously pressed radially inwards and thereby clamping the bolt.

[0007] With such support devices, it is common for the weight of the machining unit to change during the machining process. This is even more crucial when the piece being machined is a workpiece that is directly subject to the machining process. Therefore, both the weight and the weight change are relevant variables that are of particular importance for different work steps. For example, a powerful yet precisely running drive motor is required to be able to rotate or position a correspondingly heavy workpiece on a turntable. Since such drives are usually designed as electric motors, they are assigned a characteristic curve for the purpose of motor control, which is determined based on empirical values ​​and the original weight.However, due to the change in weight during operation, this characteristic curve cannot be adjusted precisely, since the control unit required for this does not receive immediate feedback about such a weight loss.

[0008] From WO 2021 / 01 8408, which forms the basis for the preamble of claim 1, it is also known to use sensors which determine the clamping force between a machining unit and the clamping device.

[0009] The present invention is based on the object of providing a carrier device which is characterized by more effective and precise working behavior compared to the carrier devices known so far.

[0010] This object is achieved by a carrier device according to patent claim 1, a processing machine according to patent claim 11 and a method for operating a carrier device according to the invention according to patent claim 12.

[0011] Accordingly, it is provided that the at least one clamping device is assigned a force sensor, which is designed to detect a force acting from the machining unit on the at least one clamping device. This force is the weight force or a weight component of a clamped machining unit, wherein the weight component is determined based on the orientation of the clamping device or the base body.

[0012] The force sensor itself can basically be designed in different ways and is arranged outside the clamping element arrangement regardless of the design. The force sensor is preferably designed as a piezoelectric force sensor. The heart of such a sensor then forms a piezoelectric crystal, e.g. quartz crystal. When force is applied, such a piezoelectric crystal releases a charge which is proportional to the force acting on the crystal. The charge can then be measured and the acting force determined using appropriate electronics. Alternatively, the force sensor can also be designed as an inductive force sensor. In addition, the force can also be determined using so-called strain sensors. If the force sensor is designed as a strain sensor, the strain is determined using strain gauges.The elasticity of the stretching material can then be used to determine the force applied. Furthermore, it is also possible to design the force sensor as a spring-loaded sensor, so that the force applied can be determined based on deformation and knowledge of the spring constant.

[0013] According to a preferred embodiment of the invention, the force sensor is designed at least to detect a force acting parallel to the axis of rotation. Such a design is particularly useful when the base body is arranged substantially horizontally before or during the machining process or can be pivoted into a horizontal position, so that the axis of rotation is then arranged obliquely or parallel to the weight of the machining unit arranged in the at least one clamping device. In the case of a machining unit arranged parallel to the weight, the weight of the machining unit can then be determined directly via the at least one force sensor. If the axis of rotation is or can be arranged obliquely, the carrier device preferably also has a protractor, via which the inclination of the base body and thus also of the axis of rotation can be determined.Based on the data determined by at least one force sensor and the protractor, the weight of the processing unit can then be determined.

[0014] Although preferably at least one force acting parallel to the axis of rotation should be detected by the force sensor, in a further development of the invention the force sensor can also detect forces along multiple axes. For example, it is conceivable for the force sensor to also be designed to detect forces acting perpendicular to the axis of rotation and, in particular, to be able to detect forces acting in all spatial directions. This makes it possible to detect the weight of the machining unit even in the case of a base body with an axis of rotation arranged perpendicular to the acting weight force. Furthermore, the force sensor can also be designed to detect moments, so that tilting moments due to an uneven weight load can also be detected by the at least one force sensor. Within the scope of the invention, therefore, reference is also made to forces with regard to moments.

[0015] In order to be able to detect the weight force of a machining unit directly on the at least one clamping device using the at least one force sensor, different embodiments are fundamentally suitable. According to a first alternative, the at least one clamping device is supported on the base body exclusively via the at least one force sensor. Accordingly, the at least one force sensor forms the only possible path via which a weight force acting from the machining unit on the clamping device can be transmitted to the base body. Since the clamping device is only attached to the base body via the force sensor, a weight force cannot act directly from the clamping device on the base body. Such a configuration has the advantage that the clamping force acting from the clamping device on the machining unit has no influence on the measurement with the at least one force sensor.Regardless of whether the clamping element arrangement is in a fixed or released state, the actual force exerted by the machining unit on the clamping device is always measured. This makes it possible to perform continuous measurements during operation or independently of the clamping element arrangement, or to perform measurements at different times without first having to release the clamping element arrangement. Support is preferably parallel to the first direction or the rotation axis.

[0016] Alternatively, it is also possible to arrange the force sensor not between the clamping device and the base body, but rather between the clamping device and the machining unit. According to such an embodiment, the at least one force sensor is then arranged in an upper section of the at least one clamping device facing the machining unit in such a way that, when the clamping element arrangement is released, the machining unit is supported on the at least one clamping device exclusively via the force sensor. Since the force sensor is now located between the machining unit and the clamping device, in a fastened state, not only the force acting by the machining unit is measured, but also the clamping force acting by the clamping element arrangement, so that the determination of the weight force can only take place in a released state.According to such an embodiment, the clamping element arrangement must therefore be released between two successive machining steps. Only then can the weight force be measured or determined. The clamping element arrangement is then returned to a fastened state and the next machining step can begin. The upper section facing the machining unit can be a housing section of the clamping device, which on the one hand enables the introduction of a section of the machining unit and at the same time allows the accommodation of the force sensor. Regardless of the specific embodiment of the invention, the force sensor is preferably provided as a load cell which, if arranged on an upper section of the clamping device, has at least one central opening through which the section of the machining unit to be fastened can be passed.

[0017] Although the carrier device can be designed in a variety of ways and can serve to hold both a tool and a workpiece, it is preferably designed in the form of a rotary table. According to such a configuration, the base body is designed as a receiving plate which is arranged so as to be rotatable relative to a mounting body. The at least one clamping device is then fixed to the receiving plate in a non-rotatable manner. Accordingly, the mounting body represents the area via which the carrier device is mounted or fastened in a processing machine. The receiving plate then forms the actual rotary table to which the at least one clamping device is fastened in one of the ways described above. With the aid of the rotatable receiving plate, the workpiece or the workpiece fastened on a pallet can be rotated and positioned.Preferably, the rotary table can be used not only for positioning, but also for generating the rotation required for chip removal. For this purpose, a fast-rotating drive motor is used, which generates a sufficiently high speed and torque so that a chip removal process can be carried out by applying a tool.

[0018] In such a configuration, the mounting plate preferably has at least one cavity in which the at least one clamping device is arranged, with the upper section of the clamping device protruding from an outer surface of the mounting plate facing the machining unit. This ensures that the machining unit rests exclusively on the at least one clamping device, so that the weight force is transmitted entirely to the base body via the at least one clamping device. Accordingly, the clamping device then has a sufficiently large contact surface so that the force exerted by the machining unit can be dissipated over the largest possible area.

[0019] According to a further development, at least three clamping devices are arranged on the rotatable support plate, each of which is assigned a force sensor. Accordingly, force can be measured on at least three separate clamping devices, all of which are attached to the base body in the same way. By using three different clamping devices, it is possible to fix the machining unit in at least three positions on the base body. This is particularly advantageous for large and / or heavy machining units. The weight can then be recorded via a measurement on all three force sensors together. Alternatively, it is also possible to clamp several machining units to one of the clamping devices instead of just one machining unit, whereby the weight of only one machining unit is measured accordingly using the respective force sensors.Preferably, however, not only three but at least or exactly four clamping devices are provided.

[0020] According to a further development of the invention, the clamping devices are arranged one behind the other in the circumferential direction. In the context of the invention, the "circumferential direction" refers to a direction that runs perpendicular to the first direction or the axis of rotation with respect to a rotary table or, in a configuration with a rotatable support plate, with the axis of rotation representing the central axis of such a circumferential direction. If the clamping devices are then arranged one behind the other along the circumferential direction, they preferably have the same distance in the radial direction from the axis of rotation, resulting in a symmetrical arrangement with respect to the geometric configuration. This also means that the distances between two consecutive clamping devices in the circumferential direction are constant, and the clamping devices therefore define a uniform division of the circumference.If three clamping devices are provided, they are spaced apart from each other in the circumferential direction at an angular distance of 120°. However, it is particularly preferred to provide four separate clamping devices on the base body, so that they are spaced apart from each other in the circumferential direction at an angular distance of 90°.

[0021] According to a further development of the invention, an electric motor is assigned to the base body and / or the at least one clamping device as a drive motor. This is preferably a so-called torque motor. Torque motors are brushless permanent magnet synchronous motors that achieve high torque with a comparatively small size and at medium speed. In particular, a high degree of positioning accuracy is achieved, making such motors particularly suitable for machine tool construction. Furthermore, by incorporating electrically operated drive motors, the characteristic curve can be specifically adapted to the required loads. For example, with a particularly heavy machining unit, a high torque is applied at the beginning of rotation, whereas this torque may be lower with a comparatively light load.This results in greater efficiency in terms of both the performance to be achieved and the energy required.

[0022] Based on such an embodiment, a particularly preferred embodiment provides for a control unit to be provided which is designed to detect the force or weight determined by the at least one force sensor, to determine at least one characteristic property of the machining unit on the basis of the determined force, and to determine at least one drive parameter for the at least one drive motor on the basis of the characteristic property. The drive motor of the carrier unit and / or of the at least one clamping device is then controlled and / or regulated on the basis of the at least one drive parameter. The characteristic property is in particular the weight of the machining unit. Especially when using multiple clamping devices or force sensors which can also detect tilting moments, the characteristic property can also be a weight distribution orIt could be an imbalance.

[0023] Preferably, the control unit has a memory unit, wherein the data stored in the memory unit enables a comparison between the characteristic properties and the drive parameters.

[0024] The invention further relates to a processing machine, e.g., a milling machine, a lathe, or a milling / lathe according to claim 11, with a carrier device according to the invention for receiving a workpiece or for receiving a pallet with a workpiece and a processing head designed to machine the workpiece. Accordingly, the processing head is a turning head, a milling head, or a turning / milling head.

[0025] The invention further relates to a method for operating a carrier device according to the invention according to claim 12, wherein the at least one force sensor detects a force or force component acting from the processing unit on the at least one clamping device and transmits it to the control unit, wherein the control unit determines characteristic properties of the processing unit on the basis of the detected force and determines at least one drive parameter based on the characteristic properties, and wherein the control unit controls and / or regulates the drive motor of the carrier unit and / or the at least one clamping device on the basis of the at least one drive parameter.

[0026] All of the features previously mentioned in connection with the carrier device naturally also apply to the processing machine or to the method for operating the carrier device according to the invention. According to the method, the measurement of the force or force component acting on the force sensors from the processing unit is now used to determine characteristic properties of the processing unit. As already explained, this particularly concerns the weight or weight distribution or imbalance of the processing unit. In addition, other parameters can of course also be included in the determination of the characteristic properties. For example, the position of the processing unit can be recorded using a protractor and the data obtained from this can be used in combination with the data from the measuring sensors to determine, for example, the weight.

[0027] Accordingly, the control unit preferably determines the weight of the machining unit as a characteristic variable based on the detected forces. Alternatively or additionally, several clamping devices are arranged one behind the other in the circumferential direction, and each of these clamping devices is assigned a force sensor. The machining unit rests on the base body via the clamping devices, and the control unit determines the weight distribution of the machining unit as a characteristic variable based on the detected forces.

[0028] Of course, the weight distribution can also be determined using only one force sensor, in which case the force sensor is designed and configured to detect moments.

[0029] The measurement and / or determination of the drive parameters can be performed either continuously or discontinuously between two work processes. Furthermore, with discontinuous measurement, the clamping element arrangement of the at least one clamping device can be released between two consecutive machining steps, so that, even when the force sensor is arranged between the machining unit and the clamping device, the weight of the machining unit can be determined based on the measurement of the at least one force sensor.

[0030] Regardless of the specific design, it is therefore possible to determine the weight or weight distribution of the machining unit at different times during the machining process and adjust the drive motor's drive parameters based on these characteristics. This enables highly targeted control and regulation of the drive motor.

[0031] The invention is explained in more detail below using an exemplary embodiment. The figures show: Fig. 1, 2 a carrier device according to the invention designed as a turntable, Fig. 3 a cross section through the carrier device according to the Fig. 1 , Fig. 4 a detailed view of a clamping device installed in the carrier device and Fig. 5 an isolated representation of a clamping device with a force sensor.

[0032] The Fig. 1 shows a support device designed as a rotary table with a base body 1 designed as a receiving plate, which is rotatably arranged on a mounting body 2. The rotary table shown is designed such that the base body 1 is aligned horizontally in a proper assembly state, so that a processing unit 3 rests flat on the base body 1.

[0033] In this context, the processing unit 3 is only in the Fig. 2 , in this case a pallet is shown on which a workpiece to be machined can be secured via an additional clamping mechanism. For clarity, the machining unit 3 has been omitted from the remaining figures.

[0034] To secure the machining unit 3 to the base body 1, a total of four clamping devices 4 are provided, each of which is identically designed. It is also clearly visible that the four clamping devices 4 are arranged along the circumferential direction U, and any two consecutive clamping devices 4 are always spaced at the same angular distance of 90° from each other. This creates a symmetrical configuration, ensuring a uniform load on all four clamping devices 4.

[0035] In particular, based on a comparative analysis with the Fig. 3 It becomes clear how the four clamping devices 4 are attached to the base body 1. The base body 1 has four cavities 5 in each of which the clamping devices 4 are inserted, with an upper section 6 protruding from an outer surface 7 of the base body 1. Furthermore, a force sensor 8 is arranged between the base body 1 and the clamping devices 4, which is designed to detect a force acting on the clamping devices 4 from the processing unit 3.

[0036] Especially in comparison with the Fig. 4 It becomes clear that the force sensors 8 are designed as ring-shaped load cells and the clamping devices 4 are supported on the base body 1 exclusively via the force sensors 8.

[0037] With the help of the force sensors 8, it is now possible to detect a force acting parallel to the rotational axis D, regardless of the clamping state of the clamping devices 4. Due to the horizontal arrangement of the base body 1, the weight of the machining unit 3 also acts perpendicular to the rotational axis D, so that the weight of the machining unit 3 can be determined with the help of the four clamping devices 4.

[0038] The carrier device has, according to the Fig. 1 and 3a control unit 9 with a storage unit 10, which is configured to record the force determined by the force sensors 4 and, based on the determined force, to determine at least one characteristic property of the processing unit 3. This characteristic property can be the weight on the one hand, but also the weight distribution or possible imbalances, which can be determined due to the four clamping devices 4 arranged at different positions. Based on these characteristic properties, a comparison with relevant drive parameters can then be made via the storage unit 10, wherein the drive motor 11 is controlled or regulated on the basis of these drive parameters. This can take place continuously during the clamping process.However, an embodiment is preferred in which a measurement is carried out by means of the force sensors 4 between two successive processing steps and then an adjustment of the drive parameters takes place.

[0039] The specific design of the clamping devices can in particular Fig. 4 and 5 be taken.

[0040] The clamping devices 4 are essentially rotationally symmetrical and are pneumatically operated.

[0041] The clamping device 4 has a cylinder housing 12 with a piston 13 that is displaceable in the axial direction X. The axial direction X represents the first direction running along the axis of rotation D within the framework of the support device. At the upper end of the clamping device 4, a circular opening 14 is provided, into which a drawbar 15 can be inserted. This drawbar 15 can then be attached either to a pallet or directly to a workpiece in the sense of a machining unit 3. By moving the lifting piston 13, the individual clamping elements of the clamping element arrangement 16 are moved inwards in a direction running perpendicular to the axial direction X and partially engage in an annular groove or two annular grooves of the draw bolt 15.

[0042] By moving the lifting piston 13 in an opposite direction, the individual clamping elements of the clamping element arrangement 16 can be pushed outwards again and the tension bolt 15 can be removed.

[0043] Furthermore, the force sensor 5 is arranged on a lower section of the clamping device 4, via which the clamping device 4 can be fastened to the base body 1, so that the clamping device 4 is supported on the base body 1 exclusively via the force sensor 5.

Claims

1. A carrier device for a cutting processing machine with a base body (1) and at least one clamping device (4) that is arranged on the base body (1) and serves for fastening a processing unit (3), wherein the at least one clamping device (4) and / or the base body (1) is designed so as to be rotatable along a rotational axis (D) extending in a first direction, wherein the at least one clamping device (4) has a clamping element arrangement (16) that is designed for at least partially engaging into the processing unit (3) in a fastening state by moving clamping elements in a direction extending perpendicular to the rotational axis (D), and wherein a force sensor (8) is assigned to the at least one clamping device (4), characterized in that the force sensor (8) is designed for measuring a weight force or weight force component exerted upon the at least one clamping device (4) by the processing unit (3).

2. The carrier device according to claim 1, characterized in that the force sensor (8) is designed for at least measuring a force acting parallel to the rotational axis (D).

3. The carrier device according to claim 1 or 2, characterized in that the at least one clamping device (4) is exclusively supported on the base body (1) by the at least one force sensor (8).

4. The carrier device according to claim 1 or 2, characterized in that the at least one force sensor (8) is arranged in an upper section (6) of the at least one clamping device (4) in such a way that the processing unit (3) is exclusively supported on the at least one clamping device (4) by the force sensor (8) in a released state of the clamping element arrangement (16).

5. The carrier device according to one of claims 1 to 4, characterized in that the base body (1) is realized in the form of a receiving plate and arranged so as to be rotatable relative to a mounting body (2), wherein the at least one clamping device (4) is fixed on the receiving plate.

6. The carrier device according to claim 5, characterized in that the receiving plate has at least one cavity (5), in which the at least one clamping device (4) is arranged, wherein the upper section (6) of the clamping device (4) protrudes relative to an outer surface (7) of the receiving plate.

7. The carrier device according to claim 5 or 6, characterized in that at least three clamping devices (4) are arranged on the rotatable receiving plate, wherein a force sensor (8) is assigned to each of the clamping devices (4).

8. The carrier device according to claim 7, characterized in that the clamping devices (4) are arranged successively in the circumferential direction (U).

9. The carrier device according to one of claims 1 to 8, characterized in that an electric motor in the form of a rotary driving motor (11) is respectively assigned to the base body (1) and / or the at least one clamping device (4).

10. The carrier device according to claim 9, wherein a control unit (9) is provided and designed for acquiring the force measured by the at least one force sensor (8), determining a characteristic property of the processing unit (3) on the basis of the measured force, determining at least one drive parameter for the at least one driving motor (11) by means of the characteristic property and controlling and / or regulating a driving motor (11) of the base body and / or the at least one clamping device (4) on the basis of the at least one drive parameter.

11. A processing machine with a carrier device according to one of claims 1 to 10 and a processing head that is designed for processing the workpiece by means of cutting.

12. A method for operating a carrier device according to claim 10, wherein the at least one force sensor (8) measures a force exerted upon the at least one clamping device (4) by the processing unit (3) and transmits said force to the control unit (9), wherein the control unit (9) determines characteristic properties of the processing unit (3) on the basis of the measured force and ascertains at least one drive parameter by means of the characteristic properties, and wherein the control unit (9) controls and / or regulates the driving motor (11) of the base body (1) and / or the at least one clamping device (4) on the basis of the at least one drive parameter.

13. The method according to claim 12, wherein the control unit (9) determines a characteristic parameter in the form of the weight of the processing unit (3) on the basis of the measured forces.

14. The method according to claim 11 or 12, wherein multiple clamping devices (4) are arranged successively in the circumferential direction (U) and a force sensor (8) is respectively assigned to each clamping device (4), wherein the processing unit (3) rests on the base body (1) by means of the clamping devices (4), and wherein the control unit (9) determines a characteristic parameter in the form of the weight distribution of the processing unit (3) on the basis of the measured forces.