Chuck

Abstract

The invention relates to a chuck. The invention relates to a chuck (1) for clamping a pallet (46) having a clamping bolt (47). The chuck (1) has a receiving opening (5) for the clamping bolt (47) and a clamping device. The clamping device comprises an actuating piston which can be displaced between an initial position and a locking position in order to actuate a clamping member, by means of which the clamping bolt (47) is clamped in the receiving opening (5). The chuck (1) has a monitoring line which can be pneumatically acted and leads from an inlet to an outlet, and the receiving opening (5) comprises a conical insertion area (6), into which at least one control hole (7) connected to the monitoring line emerges, the control hole being able to be closed by means of the clamping bolt (47), and a valve device is arranged between the inlet and the outlet of the monitoring line, by means of which the flow of a fluid through the monitoring line can be varied depending on the position of the actuating piston.

Description

Technical Field

[0001] The present invention relates to a chuck for clamping a pallet having a clamping pin, a clamping device for clamping a pallet, a chuck arrangement structure and a method for detecting a clamping state of a pallet clamped on the chuck arrangement structure. Background Art

[0002] Chucks of the type discussed here are used for defined position clamping of pallets and / or workpiece carriers. In addition to single chucks for clamping pallets or workpiece holders (with one spigot), multi-chucks are also known, which include at least two chucks for clamping pallets (with a corresponding number of spigots). Such multi-chucks are also specifically referred to as clamping devices below, wherein their chucks are arranged on a clamping base. The term chuck arrangement structure is used to refer to the corresponding single or multiple chucks, including its surroundings, such as connections or pressure lines, sensors, pressure regulators, throttles, etc.

[0003] The chuck or the corresponding clamping base is usually mounted and fixed on the machine table of the processing machine, and the pallet can be clamped on the chuck or the clamping device accurately and repeatedly. The corresponding chuck has a receiving opening and a clamping device for clamping the clamping bolt in the receiving opening. The pallet usually carries the workpiece or tool to be processed.

[0004] When such a chuck or clamping base is used in a work process which is carried out semi-automatically or fully automatically, the pallet is usually fed to the chuck or clamping device and removed from it again by means of a handling robot. It is important that the pallet is securely clamped and held. If, for example, the pallet is not correctly fixed on the chuck or clamping device, there is a risk that the chuck or clamping device can work loose during machining of the workpiece clamped thereon, for example during a milling process, which can lead to considerable damage and endanger personal safety.

[0005] EP 1 344 599 A1 discloses a clamping device with a chuck and a clamping bolt that can be clamped thereon. The chuck has a central opening for receiving the clamping bolt. The chuck also comprises a plurality of openings for blowing out air. Some of these blow-out openings are arranged in the conical insertion section of the central opening and can be closed by means of the clamping bolt or its centering surface section. The blow-out openings are only used for cleaning the above-mentioned centering surface section.

[0006] A clamping device is known from EP 2 052 808 A1, which has a releasably fixed chuck for a workpiece carrier. The chuck has a locking mechanism comprising a plurality of clamping elements, which engage in a clamping bolt connected to the workpiece carrier when in a locked position. Each clamping element has a through hole, which is closed on one side when the corresponding clamping element is correctly locked. In addition or alternatively, an actuating element with a through hole is assigned to each clamping element, and the through hole about it is closed on one side when the corresponding clamping element is correctly locked and / or unlocked. The through hole of the clamping element or the actuating element is connected to a pneumatic source via a common connecting line. At least one sensor for detecting an airflow is provided in the connecting line. With the aid of the sensor, it is possible to detect whether the clamping element has been correctly released or clamped. The sensor is connected to an electronic control and evaluation device.

[0007] A quick-acting clamping cylinder for clamping a retractable nipple is known from EP 2 177 309 A1. The quick-acting clamping cylinder is intended to be used to control the function of the retractable nipple during clamping. The quick-acting clamping cylinder comprises a housing having a central cutout for receiving a retractable nipple arranged on a pallet. A locking mechanism with a pressure medium-actuated piston and a plurality of locking bodies is arranged in the housing. The piston moves into a locked position by means of a set of springs and is unlocked in a pressure medium-actuated manner. Arranged in the displacement path of the set of springs is a first actuating element, whose actuation signal is monitored. A second actuating element is located upstream of the control flow of the first actuating element, which detects the displacement state of the retractable nipple. The two actuating elements are designed as switches in the form of fluid control valves, which can be actuated depending on the path, the fluid control valves being arranged in a control line and opening or closing the latter in a state-dependent manner.

[0008] Another quick-acting clamping cylinder for clamping a retractable nipple is known from EP 2 218 541 A1. This quick-acting clamping cylinder seeks to provide control means for correctly locking the retractable nipple in the housing of the quick-acting clamping cylinder. For this purpose, a spring-loaded actuating element is arranged in the housing of the quick-acting clamping cylinder, which can be actuated by the retractable nipple against the spring force and whose displacement path controls the passage for the control medium.

[0009] Finally, US 4,504,824 A discloses a tool sensing system for a processing machine (milling machine). The processing machine has a stationary part, and a spindle is usually rotatably mounted inside the stationary part. The tool holder has a conical cutout for receiving the conical shaft of the processing tool. The stationary part has an annular chamber around the spindle, and radial holes pass through the spindle to the conical cutout. The annular chamber is connected to a pressure source via a pipeline, wherein a pressure regulator is arranged in the pipeline. In addition, the pipeline is connected to a pressure switch. Once the processing tool is received and clamped in the holder, the radial holes from the conical shaft of the processing tool are closed, which can be monitored by means of a pressure switch. Summary of the invention

[0010] The object of the present invention is to develop a chuck for clamping a pallet with clamping pegs, for clamping a pallet with clamping pegs, making it possible to monitor the presence of the pallet in the chuck.

[0011] The technical solution of this object is defined by the technical solution of the invention. According to the invention, the chuck has a monitoring line that can be acted on pneumatically and leads from an inlet to an outlet, wherein the receiving opening comprises a conical insertion area into which at least one control hole connected to the monitoring line emerges, which control hole can be closed by means of a clamping bolt.

[0012] Since the chuck has a monitoring line that can be pneumatically acted and leads from the inlet to the outlet and the receiving opening includes a conical insertion area, at least one control hole connected to the monitoring line is exposed in the conical insertion area, and the control hole can be closed by means of a clamping bolt, so a basic possibility of establishing the presence of the clamping bolt in the receiving opening is provided. The specific advantage of this embodiment lies in the fact that the chuck can be incorporated into the infrastructure / periphery of the processing machine that usually already exists with relatively little effort. Since such a processing machine usually includes at least one pneumatic pressure line to open and / or close the chuck, compressed air can also be used to act on the monitoring line with it and measure the pressure therein at a given time. As long as no clamping bolt is received in the receiving opening of the chuck, the pressure escapes via the control hole, which can be measured by means of a pressure sensor connected to the monitoring line and recorded and evaluated by means of an evaluation electronics. Since evaluation electronics are usually also present, only the evaluation electronics need to be software adapted in addition to at least one pressure sensor.

[0013] Preferred embodiments and developments of the chuck are described in the preferred embodiments.

[0014] Therefore, in a preferred development, a clamping device of a chuck is provided, which comprises an actuating piston displaceable between an initial position and a locking position for actuating the clamping member, and the chuck comprises a valve device arranged between the inlet and the outlet of the monitoring line, by means of which the flow of the fluid through the monitoring line can be varied depending on the position of the actuating piston. The position of the actuating piston can be determined by means of such a valve device. Together with the technical solution of the invention, the presence of the clamping bolt and its correct clamping in the chuck can be checked by means of such an embodiment.

[0015] The valve device preferably comprises a valve housing and a valve body at least partially accommodated therein, the valve body being displaceable relative to the valve housing between a closed position and an open position in order to change the flow of the fluid through the monitoring line. Such a valve device is particularly suitable for mechanically coupling with an actuating piston so that the latter can open or close the valve device.

[0016] Particularly preferably, the valve body is in the open position when the actuating piston is correctly displaced into the locking position, and in the closed position when the actuating piston is not correctly displaced into the locking position. Thus, a basic prerequisite for positive reliability is created, wherein the valve body only occupies the open position when the actuating piston occupies the locking position required for reliable clamping of the clamping bolt. As long as the monitoring line is subjected to excess pressure at the inlet side, the position of the valve body and therefore of the actuating piston can be easily determined by comparing the pressures before and after the valve body.

[0017] In a further preferred development of the chuck, the valve body is arranged to be stationary, while the valve housing is connected to the actuating piston in a firmly bonded manner. On the one hand, the moving parts can thus be kept small, which leads to good utilization of space. On the other hand, the radial and axial play of the inner housing part can also be kept small, because in the case of a reversal of the movement, i.e. when the valve body is arranged to be movable and the housing is stationary, the above-mentioned play would have to be increased due to the lever action. In addition, this embodiment is also particularly suitable for series connection of valve devices.

[0018] In a particularly preferred development, the valve housing comprises a first outer part and a second inner part, wherein the outer part is connected to the actuating piston in a firmly bonded manner, and the inner part is connected to the outer part in a form-fitting manner, and wherein the inner part is accommodated in the outer part with radial play. Such an embodiment enables the valve device to slightly compensate for play in the radial direction and thus function reliably. This is therefore advantageous, since the actuating piston must always have some radial play in order for it to function reliably over time and to be able to reliably move back and forth between the initial position and the locking position.

[0019] A preferred development of the chuck is such that the axial inlet opening leads from the upper side into the valve body and the axial outlet opening leads from the bottom side into the valve body, wherein the axial inlet opening emerges into the first radial through hole, and wherein the axial outlet opening emerges into the second radial through hole, and wherein the first radial through hole extends above the second radial through hole, and wherein the inner part of the valve housing has an annular space, whose axial length corresponds at least to the distance between the two radial through holes, and wherein the annular space extends above the two radial holes when the actuating piston is in its locking position. Such a valve device is reliable and simple in design. Furthermore, the previously mentioned "floating" accommodation of the interior in the outer housing part can therefore be implemented particularly well.

[0020] Particularly preferably, when the clamping bolt is received in the receiving opening of the chuck and is correctly locked by means of the clamping device, the monitoring line is continuously open between the inlet and the outlet, but is closed to the atmosphere. Such an embodiment also contributes to positive reliability, wherein a sufficient predetermined pressure can be built up at the outlet side only when the clamping bolt is received and likewise correctly locked in the corresponding chuck.

[0021] A further object of the invention is to develop a clamping device with at least two chucks according to the invention for clamping a pallet with a number of clamping pegs corresponding to the number of chucks, so that it is possible to verify in a straightforward manner whether the clamping pegs are received in all chucks.

[0022] The technical solution of this object is defined by the technical solution of the invention. For this purpose, the chucks of the clamping device are accommodated in a common clamping base, wherein the clamping base has a monitoring line that can be acted pneumatically and leads from an inlet to an outlet, and wherein the monitoring line is connected to all control holes provided in the insertion area of ​​the respective chuck.

[0023] By means of such an embodiment, a basic possibility is provided to check by means of the monitoring line whether the clamping bolts are received in all chucks, since sufficient pressure can be built up in the monitoring line only when all control openings are closed in each case by the clamping bolts.

[0024] Very particularly preferably, each chuck of the clamping device comprises a valve device by means of which the flow of the fluid through the monitoring line can be varied depending on the position of the actuating piston, wherein the valve devices are arranged between the inlet and outlet of the monitoring line and are connected in series with one another so that a passage exists between the inlet and outlet of the monitoring line only when all actuating pistons are correctly locked. In the case of such an embodiment, a sufficient pressure is built up at the outlet of the monitoring line only when all clamping bolts are correctly locked.

[0025] Another particularly preferred development provides that in the region of the respective chuck, a pneumatic refastening line opens into a refastening space arranged above the respective actuating piston, wherein each refastening line is directly or indirectly connected to a monitoring line. This embodiment makes it possible to refasten all actuating pistons by introducing compressed air into the monitoring line. Since a "refastening line" is usually already provided in a universal clamping device, an existing refastening line can be used simultaneously with the monitoring line. For this purpose, relatively small adaptations of the existing clamping device are required, in particular since an inlet and an outlet with a coupling are already present.

[0026] A further object of the present invention is to achieve a chuck arrangement structure having a chuck or clamping device according to the present invention, which has means for monitoring the presence and correct clamping of a pallet with a clamping pin in the chuck or has means for monitoring the presence and correct clamping of a pallet with multiple clamping pins in the clamping device.

[0027] This object is achieved with the chuck arrangement according to the invention.

[0028] Because the chuck arrangement comprises an inlet line which can be connected to a pneumatic pressure source and to the inlet of a monitoring line passing through the clamping base, and because the monitoring line is connected to an outlet line on the outlet side and the outlet line is connected to at least one pressure sensor for detecting the pressure at the outlet side, the presence and correct clamping of the pallet in the chuck or clamping device can be monitored by means of the pressure sensor at the outlet side.

[0029] A preferred development of the cartridge arrangement provides that a throttle valve which limits the flow of air is arranged in the inlet line, wherein the inlet line is connected to a first pressure sensor and the outlet line is connected to a second and a third pressure sensor for detecting the pressure prevailing in the monitoring line at the outlet side, and wherein the cartridge arrangement comprises evaluation electronics for recording and evaluating the pressures determined with the aid of the three pressure sensors.

[0030] Since a throttle valve which limits the amount of air flowing is provided in the inlet line and detects the inlet pressure on the one hand and the pressure prevailing in the outlet line on the other hand by means of two pressure sensors, reliable information can be obtained as to whether the respective pallet is correctly clamped in the chuck or the clamping device, in particular since a comparison can be made between the pressure at the inlet side and at the outlet side. Monitoring also becomes redundant due to the provision of two pressure sensors at the outlet side.

[0031] Finally, a further object of the present invention is to provide a method for detecting the clamping state of a pallet clamped on a chuck arrangement according to the present invention, with which method a reliable and safe monitoring of the clamping state can be achieved. This object is achieved by the process steps according to the present invention.

[0032] In order to enable a pressure build-up in the pneumatic system, i.e. in the monitoring line with the associated components, the inlet line is pressurized and, after a predetermined time, the pressure in the inlet line is measured and compared with the pressure measured at the outlet or the pressure measured in the outlet. If the pressure difference measured between the inlet and the outlet is less than 25%, a correct clamping of the pallet is detected. On the other hand, if a pressure difference between the inlet and the outlet reaches more than 25%, a defective clamping of the pallet is detected. The above information is based on previously empirical values. Depending on the size and design of the chuck or the clamping device, these values ​​may differ from the above orders of magnitude. The only important point is that there is a clear and reliably measurable difference between a correctly and an incorrectly clamped pallet.

[0033] A preferred development of the method provides that two pressure sensors for detecting the pressure are arranged in the outlet line of the chuck arrangement, which is connected to the monitoring line at the outlet side, wherein the inlet line is pressurized and the pressure in the inlet line is measured after a predetermined time and compared with the pressure measured by means of the two pressure sensors arranged at the outlet side, and in the event of a measured pressure difference between the two pressure sensors arranged at the outlet side of greater than 10%, an error message is output and / or a defective clamping of the pallet is detected. Defective pressure sensors can thus be identified, which contributes to increased security with regard to reliable detection of the clamping state.

[0034] Further advantageous embodiments and combinations of features of the invention emerge from the following detailed description and from all claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In the figure of the accompanying drawings for explaining an example of an embodiment:

[0036] Figure 1 The chuck is shown in perspective view together with the tray;

[0037] Figure 2 A partial cross-sectional perspective view shows Figure 1 Chuck;

[0038] Figure 3 An alternative cross section is shown according to Figure 1 Chuck;

[0039] Figure 4 The chuck is shown in partial cross-sectional perspective view together with the tray clamped thereto;

[0040] Figure 5 An alternative cross section is shown according to Figure 4 a chuck with a tray clamped thereon;

[0041] Figure 6 Shows Figure 4 Magnified details of

[0042] Figure 7 A chuck arrangement with a chuck is shown with the aid of a simplified diagram;

[0043] Figure 8 A clamping device having four chucks is shown;

[0044] Fig. 9 The chuck arrangement with the clamping device is shown with the aid of a simplified illustration. DETAILED DESCRIPTION

[0045] Figure 1 The chuck 1 is shown in a perspective view together with a tray 46. The tray 46 has a clamping bolt 47 arranged on the bottom side. The term tray here represents any type of carrier, on which, for example, a tool or a workpiece can be fastened. The chuck 1 accommodated in the clamping base 20 comprises a circular clamping plate 2, which has a hollow cylindrical extension, which extends vertically downward into a cutout of the clamping base 20. The inner space of the hollow cylindrical extension forms a receiving opening 5 for the clamping bolt 47.

[0046] The clamping plate 2 is arranged on the upper side and has outer and inner Z supports 3a, 3b for the tray 46, wherein both the outer Z supports 3a and the inner Z supports 3b are arranged to be evenly distributed along a circle. The insertion area 6 of the receiving opening 5 is formed as a cone. Two control holes are exposed in the insertion area 6, which are opposite in diameter and whose functions will be explained in more detail below, wherein only one of the two control holes 7 can be seen from this figure. The control hole 7 preferably has a diameter between approximately 2 and 3 mm. A plurality of cleaning holes 8 are also exposed in the insertion area 6 of the receiving opening 5, which are used to clean the conical centering area 48 of the clamping bolt 47. The chuck 1 has a clamping device not shown in this figure, which includes a spherical clamping member for the clamping bolt 47 in the receiving opening 5. The clamping device includes an actuating piston that can be displaced between an open position and a locked position to actuate the clamping member. The clamping base 20 has a plurality of channels and lines which are introduced into and out of the clamping base 20 by means of couplings / connectors 9a, 9b. One of these connectors 9a forms an inlet for a monitoring line, while the other connector 9b forms an outlet for a monitoring line, as will be described below by means of Figure 7 More specific explanation.

[0047] The clamping pin 47 has, on its rear side facing the tray 46, a conical centering area 48 which matches the conical insertion area 6 of the chuck 1. Towards the front end, the clamping pin 47 has a conical front section 49, the rear side of which forms a shoulder 50 into which a clamping member of the clamping device can engage in order to pull the clamping pin 47 into the chuck 1 and fix it.

[0048] Figure 2 The chuck 1 in the open position together with the clamping base 20 is shown in a partially cross-sectional perspective view. Since the basic design of such a chuck is known, for example, from EP 1 321 221 A1, all elements of the chuck will not be discussed below, but several elements that are substantially related to the present invention will be described in particular. Among other things, from this figure, it is possible to see the hollow cylindrical extension 4, the receiving opening 5 with the conical insertion area 6, two control holes 7, two cleaning holes 8, the clamping device 10, the actuating piston 11, the spherical clamping member 12 of the clamping device 10 and a section of the monitoring line 40, etc. By means of a compression spring (not shown) supported on the clamping plate 2, the actuating piston 11 is loaded in the direction toward the bottom of the clamping base 20. The actuating piston 11 is shown in an initial position together with the clamping member 12, where the clamping bolt can be introduced into the receiving opening 5 and also removed from it. A pressure space 27 is formed between the bottom side of the actuating piston 11 and the bottom of the clamping base 20. In order to move the actuating piston 11 to the initial position shown in the figure against the force of the compression spring, the space 27 is subjected to compressed air and a predetermined overpressure is established. Therefore, the actuating piston 11 is pneumatically pressed against the upper stop against the force of the compression spring and is displaced to the initial position shown here. In order to clamp the pallet on the chuck 1 by means of the clamping bolt, the overpressure in the pressure space 27 must be reduced. For this purpose, the pressure space 27 is preferably opened toward the atmosphere. Once the overpressure in the pressure space 27 drops below a specific value, the actuating piston 11 moves downward to its locking position by means of the compression spring. The clamping member 12 is radially displaced inwardly into the receiving opening 5, so that the clamping bolt inserted into the receiving opening 5 is further pulled into the receiving opening, i.e., pulled downward in the direction of the bottom of the clamping base 20, and is fixed or clamped in the chuck 1. The clamping device 10 is designed such that the actuating piston 11 together with the clamping member 12 holds and locks the clamping bolt in the chuck 1 by means of self-locking. Such a clamping device 10, known per se, seeks to ensure that the pallet is and remains clamped in the chuck 1 in an unpressurized state.

[0049] The chuck 1 also has a valve device 16, which forms a passage that can be shut off in the monitoring line 40. The valve device 16 includes a valve housing 17 and a substantially cylindrical valve body 21 contained therein in sections. The valve housing 17 includes a first outer part 18 and a second inner part 19, wherein the outer part 18 is connected to the actuating piston 11 in a firmly combined manner. The inner part 19 of the housing is connected to the outer part 18 in a form-fitting manner in the axial direction, wherein the inner part 19 is contained in the outer part 18 and has radial play. Both valve housing parts 18, 19 are formed in the shape of a socket. The valve body 21 is displaceably mounted relative to the valve housing 17 so as to change the flow of the fluid between the shut-off position and the open position. Air or compressed air is preferably used as fluid. The valve body 21 is fixedly connected to the clamping plate 2 by means of screws, and the outer part 18 of the valve housing 17 is fixedly contained in the hole 31 of the actuating piston 11. The valve body 21 has an axial inlet bore 22, which leads into the valve body 21 from the upper side and leads out again approximately in the middle of the valve body 21 via a first radial bore 23. The first radial bore 23 crosses the valve body 21 in the diametrical direction and emerges from the valve body 21 on both sides. A second radial bore 24 is positioned in the valve body 21, which is arranged below the first bore 23 and also crosses the valve body 21 radially. This second radial bore 24 is connected to an axial outlet bore 25, which extends downward out of the valve body 21. In the region of the two radial bores 23, 24, a groove or a slot-shaped recess is provided in each case in the lateral surface of the valve body 21. At the inside, the inner part 19 of the valve housing 17 has a recess, which forms an annular space around the valve body 21, the axial length of which corresponds at least to the distance between the two radial through-bores 23, 24. The inner part 19 of the valve housing 17 is guided and accommodated in the outer part 18 of the valve housing 17 and floats in the radial direction, i.e. has a degree of radial play of the order of tens of micrometers, while in the axial direction it is connected to the outer part 18 of the valve housing 17 in a form-fitting manner with a certain degree of play. Due to the floating bearing of the inner part 19 of the valve housing 17, the radial play of the actuating piston 11, in particular (the radial play is accommodated in the clamping base 20 with a certain degree of play in the radial direction for system reasons), can be compensated, in particular because only the inner part 19 of the valve housing 17, which is connected to the valve body 21, is functionally important for monitoring the opening and closing of the pipeline 40.

[0050] The annular space provided in the inner part 19 of the valve housing 17 is adapted to the valve body 21 so that in a predetermined first axial position of the valve body 21 relative to the inner part 19, the two radial holes 23, 24 are connected to one another via the annular space, whereas in a predetermined second axial position, the two radial holes 23, 24 are not connected to one another, since at least one hole, but preferably both holes 23, 24, are located below the annular space in the axial direction in the region of an annular protrusion in the inner part 19 which limits the annular space downwards. The latter state occurs when the actuating piston 11 is in the illustrated initial position. On the other hand, in the locked position, the two radial holes 23, 24 are connected to one another via the annular space, as described below with the aid of Figure 3 When the two radial holes 23, 24 are connected to each other via the annular space, the valve device 16 is in the open position, i.e. the inlet of the monitoring line 40 is pneumatically connected to its outlet through the valve device 16, because the annular space extends in the axial direction over the two radial holes 23, 24. In short, the monitoring line 40 is shut off by the valve device between the inlet and the outlet when the actuating piston 11 is not in the locked position, and the monitoring line 40 is continuously open between the inlet and the outlet when the actuating piston 11 is in the locked position.

[0051] The monitoring line 40 is also connected to at least one control line 15, which connects the two control holes 7 arranged in the conical insertion area 6 of the receiving opening to the monitoring line 40. If the clamping bolt is not received in the receiving opening 5, the two control holes are open, while when the clamping bolt is correctly received in the receiving opening, the two control holes 7 are closed by the conical centering area of ​​the clamping bolt. In the case of such an embodiment of the chuck, it is possible to detect by the measured pressure at the outlet of the monitoring line 40 whether the clamping bolt is correctly received in the receiving opening 5 and whether the locking piston 11 is in the locking position.

[0052] Figure 3 An alternative cross section is shown according to Figure 2chuck. In this figure, one of the plurality of compression springs 14 can be seen, which presses the actuating piston 11 downwards in the direction of its locking position. Furthermore, the inlet hole 22, which is introduced axially into the valve body 21 from the upper side, the first radial hole 23, the second radial hole 24 and the outlet hole 25, which leaves the valve body 21 axially downwards, can be seen. The annular space 30 surrounding the valve body 21 can also be seen. In this state, in which the actuating piston 11 is in its initial position of upward displacement, there is no passage between the inlet hole 22 and the outlet hole 25, since the annular space 30 is located above the two radial holes 23, 24. The lifting of the inner housing part that limits the annular space 30 downwards surrounds the lateral surface of the valve body 21 above the two radial holes 23, 24. There is therefore no pneumatic connection between the two radial holes 23, 24, except for a small leakage via the existing gap.

[0053] Figure 4 The chuck 1 with the tray 46 clamped thereon is shown in a partial cross-sectional perspective view. Once the clamping bolt 47 connected to the tray 46 is inserted into the receiving opening 5 and the tray 46 is placed on the chuck 1, the tray 46 is clamped on the chuck 1. For this purpose, the overpressure in the pressure space 27 is reduced, and the pressure space is preferably open to the atmosphere so that its pressure drops to the ambient pressure. The effect of doing so is that the actuating piston 11 moves downward to its enabled position under the action of the compression spring. As the actuating piston 11 moves downward, it presses the clamping member 12 inwardly, which then makes it partially abut against the shoulder 50 of the clamping bolt 47, and presses the clamping bolt 47 downward toward the bottom of the clamping base 20. The bottom side of the tray 46 is located on the Z support 3a of the chuck 1. When the actuating piston 11 moves downward, the valve housing also moves, that is, the outer part 18 and the inner part 19 move relative to the valve body 21, which is fastened to the clamping plate 2 and does not move. Due to the relative movement between the inner part 19 of the valve housing and the valve body 21, the valve device moves to the open position, as described below by means of Figure 6 explained in more detail.

[0054] Figure 5 The cross-sectional view shows the Figure 4 The chuck with the pallet 46 clamped thereon. Among other things, two of the compression springs 14 can be seen from this figure, which press the actuating piston 11 downwards into its final or locked position.

[0055] Figure 6 Shows Figure 4, 35 . In this figure, the annular space 30 provided in the inner part 19 of the valve housing can be seen. When the actuating piston 11 is pushed completely downwards, the annular space 30 is located above the two radial holes 23, 24 of the valve body 21. Due to the fact that the annular space 30 is located above the two radial holes 23, 24 and the valve body 21 has groove-like grooves 34, 35 in the region of the radial holes 23, 24, there is a pneumatic connection between the first radial hole 23 and the second radial hole 24 and therefore between the axial inlet hole 22 and the axial outlet hole of the valve body 21. Furthermore, the air flowing from the monitoring line 40 into the valve body 21 from above can flow via the annular space 30 from the first radial hole 23 into the second radial hole 24 and therefore from the axial inlet hole 22 to the axial outlet hole 25 ( Figure 3 ). The air can flow forward from the axial outlet opening in the direction of the outlet into the monitoring line 40. In the lower region, the outer part 18 of the valve housing has a safety ring 32, which serves as an axial drive disk for the inner part 19 of the valve housing when there is an outward movement of the outer housing part 18. It can also be seen that the outer part 18 of the valve housing has a sealing ring 33 on its inner side, which bears against a lateral surface of the valve body 21 in a sealing manner.

[0056] Figure 7 The previously explained chuck 1 and further elements of a chuck arrangement 80 with the chuck 1 are shown with the aid of a simplified diagram together with a clamping base 20. The above further elements are usually parts of the periphery of a processing machine on which the chuck is used or parts belonging to the periphery of the processing machine. In addition to the chuck 1, the chuck arrangement 18 also comprises a first pressure sensor 88 connected to the monitoring line 40 at the inlet side and two further pressure sensors 89, 90 connected to the monitoring line 40 at the outlet side. The monitoring line 40 is introduced into the clamping base 20 from the inlet 82, wherein the control line 15 branches off from the monitoring line 40 after the inlet 82, which control line is also regarded as a part of the monitoring line 40. This figure also schematically presents the actuating piston 11 of the clamping device, one of the compression springs 14, the valve device 16 for shutting off the monitoring line 40 and one of the preferably two control holes 7 arranged in the receiving opening. It can also be seen that the re-tightening line 26 branches off from the control line 15 and leads into the re-tightening space provided above the actuating piston 11. If the control line 7 is closed by the clamping bolt, sufficient pressure can be built up in the monitoring line 40 by means of a pressure source connected at the inlet side, which can also be used to re-tighten the actuating piston 11 in the locked position. Since the re-tightening of the actuating piston 11 and the detection of the pressure at the outlet side can take place more or less simultaneously, the chuck arrangement only needs to have for this purpose in each case an inlet and an outlet for the monitoring line 40, which simultaneously serves as a pneumatic re-tightening line.

[0057] The chuck arrangement 80 also includes many other elements, such as a pressure control 86, a control element 87, a throttle valve 91 and a pneumatic pressure line 92. The space 27 below the actuating piston 11 can be pressurized by means of the pressure line 92 so that the actuating piston 11 can be displaced to its initial position against the force of the compression spring 14. The pressure regulator 86 at the inlet side is connected to the inlet 82 via a line 84, and the line 85 leads from the outlet 83 to the two pressure sensors 89, 90 arranged in parallel at the outlet side. For a clearer representation, no further elements are shown, such as, for example, a pneumatic pressure source or evaluation electronics connected to the line 84. The first pressure sensor 88 arranged at the inlet side and the two further pressure sensors 89, 90 connected to the monitoring line 40 at the outlet side are connected to the evaluation electronics. Due to the fact that the two pressure sensors 89, 90 are provided at the outlet side, a cross comparison of the pressures at the respective pressure sensors 89, 90 can be performed and an error message can be output in the event of a deviation exceeding a certain limit value. In all cases, increased reliability can be achieved by means of the two pressure sensors 89 , 90 arranged at the outlet side, and a faulty pressure sensor can be detected.

[0058] The function of the chuck arrangement 80 with regard to monitoring the presence and correct clamping of the pallet is explained in more detail below with the aid of various variants, wherein in all variants it is assumed that the pressure space 27 arranged below the respective actuating piston 11 is not subject to excess pressure.

[0059] Variant 1: No tray exists.

[0060] This variant assumes that no pallet and therefore no clamping bolt is received on the chuck 1 or in the receiving opening. In order to check whether the pallet is correctly clamped in the chuck 1 by means of the clamping bolt, the monitoring line 40 is pneumatically subjected to an overpressure via the line 84 at the inlet side. After a predetermined time X, for example after 3-5 seconds, the pressure present at the connecting line 84 at the inlet side and the pressure present at the connecting line 85 at the outlet side are measured using the corresponding pressure sensors 88, 89, 90. If no clamping bolt is received in the receiving opening, the air flowing into the monitoring line 40 escapes to the atmosphere via the control orifice 7. Since the mass of the air flowing into the monitoring line 40 is limited by the throttle valve 91 at the inlet side, only a small overpressure is formed in the monitoring line 40 when no clamping bolt is present, which in all cases is well below the limit value of approximately 4.5 bar defined for correct clamping.

[0061] The size of the throttle valve depends on the ability of the air supply to maintain the inlet pressure and the line length and line cross section between the control element 87 and the inlet 82. The throttle valve must therefore be closed so that even with a short large line and a very stable air supply, the absence of the clamping bolt still leads to a significant pressure drop and can be reliably detected by the low pressure at the outlet 83. The throttle valve is therefore set so that in the absence of the clamping bolt and the correct locking of the chuck, the pressure at the outlet 83 is less than or equal to 2 bar.

[0062] In the absence of a clamping bolt, a pressure is therefore set at the two pressure sensors 89, 90 arranged at the outlet side which is much lower than the pressure of, for example, 6 bar which is preset at the inlet side by means of the pressure regulator 86. If the actuating piston 11 is in the locked position, the valve body of the valve device 16 is admittedly in the open position, but since the air flowing into the monitoring line 40 escapes via the control orifice 7, the pressure sensors 89, 90 at the outlet side measure a pressure which is much lower than the set pressure of 6 bar. The measured values ​​have shown that the pressure prevailing at the outlet side in the absence of a clamping bolt is of the order of magnitude of approximately 1.5-2.5 bar. It goes without saying that the pressure measured at the outlet side, in addition to the overpressure set at the inlet side, depends on various other parameters, such as the number and diameter of the control orifices 7, the volume of air fed in, leaks in the system, the diameter of the monitoring line 40, the taper or throttling point between the inlet and outlet, etc. The diameter of the control hole 7 arranged in the insertion area of ​​the chuck is in each case selected such that, on the one hand, a sufficiently large amount of air can escape via the control hole 7, so that a significant pressure drop occurs in the absence of the clamping bolt, and, on the other hand, the control hole 7 can be reliably sealed by means of the clamping bolt. It is particularly important that, by means of the pressure measured at the outlet side, a clear distinction is made between a correctly clamped pallet and an incorrectly clamped pallet or the absence of a pallet. The different states are preferably detected by means of a test and pressure ranges are assigned to the respective states. In the absence of a throttle valve 91 at the inlet side, there would be a risk that there would not be a sufficiently large pressure difference between the inlet and the outlet in the absence of the clamping bolt, because the measured outlet pressure can be very high in the case of short lines and a large amount of air feed-in, wherein a reliable distinction cannot be made between the presence of the clamping bolt and the absence of the clamping bolt.

[0063] If no clamping bolt is received in the receiving opening and the volume of the inflowing air is limited, as described by the throttle valve at the inlet side, the pressure escapes via the control opening 7. It is irrelevant whether the valve device 16 or its valve body is in the closed position or the open position, because in both cases, the pressure present at the pressure sensors 89, 90 arranged at the outlet side is far below the nominal pressure of 6 bar. In all cases, it is recognized by the evaluation electronics, which are not shown in detail, that the pressure present at the two pressure sensors 89, 90 does not correspond to the overpressure required for reliable clamping (e.g. 4.5 bar or 450 kPa).

[0064] Variant 2: There is a pallet including clamping pins but it is not clamped correctly.

[0065] In this variant it is assumed that the pallet is located on the chuck 1 and its clamping bolt is received in the receiving opening. If the clamping bolt is received in the receiving opening of the chuck, the control hole 7 is closed by the conical centering area of ​​the clamping bolt. However, as long as the actuating piston 11 is not in the locking position, for example it is stuck, the valve device 16 occupies the locking position and at the two pressure sensors 89, 90 connected to the monitoring line 40 on the outlet side there is again a pressure that is much lower than the inlet nominal pressure of 6 bar set by means of the pressure regulator 86. If the valve body of the valve device 16 occupies the locking position, the pressure that is therefore present at the two pressure sensors 89, 90 corresponds essentially to the ambient pressure. However, taking into account a certain leakage of the valve device 16, the measured outlet pressure will of course be slightly higher than the ambient pressure; in any case, however, the pressure in the connecting line 85 on the outlet side can be lower than 2 bar.

[0066] In the case where the actuating piston 11 is already in the locking position before the pallet is placed on the chuck 1 and its clamping bolt is inserted into the receiving opening, the clamping bolt cannot be fully inserted into the receiving opening because the clamping member is in the advanced locking position ( Figure 6 ), thus preventing the clamping bolt from being fully inserted, because the front portion 49 ( Figure 1 ) abuts against the clamping member and insertion cannot be completed. The control hole 7r is also not closed by the clamping bolt and the pressure generated at the inlet side can escape via the control hole 7. In this case as well, a pressure of less than 2 bar is present at the two pressure sensors 89, 90 at the outlet side. In this case as well, it is detected by means of the evaluation electronics that correct clamping and locking of the tray has not yet occurred.

[0067] Variant 3: The pallet is correctly clamped in the chuck.

[0068] In this variant it is assumed that the pallet is located on the chuck 1 and its clamping bolt is clamped and correctly locked by means of the clamping device. The actuating piston 11 is in the lower locking position, in which it presses the clamping member inwardly into the receiving opening. The clamping member abuts against the shoulder of the clamping bolt and, with great force, pulls the latter downward together with the pallet so that the bottom side of the pallet lies fixedly on the raised Z support of the chuck 1. All control holes 7 arranged in the insertion area of ​​the receiving opening are therefore also tightly sealed by the conical centering area of ​​the clamping bolt. In the locked position of the actuating piston 11, the two radial holes 23, 24 are connected via the inner part 19 ( Figure 6 ) are connected to each other in the valve body 21 of the valve device. Therefore, the inlet 82 of the monitoring line 40 is connected to the outlet 83 thereof.

[0069] Taking into account the leakage of the system, when the clamping bolt is correctly locked, when a nominal pressure of 6 bar is set at the inlet side by means of the pressure regulator 86, a pressure of the order of magnitude of approximately 4.5-5.5 bar is present at the two pressure sensors 89, 90 connected to the monitoring line 40 at the outlet side. In order to recognize the correct clamping of the pallet, it is necessary to measure on the one hand by means of the two pressure sensors 89, 90 at the outlet side up to at least 75% of the pressure set and possibly measured at the inlet side. Furthermore, a pressure difference of at most 10% is present and measured at the two pressure sensors 89, 90 connected to the monitoring line 40 at the outlet side, because otherwise an error message is output and / or a defective clamping of the pallet is detected.

[0070] If the monitoring line 40 does not leak but is completely sealed, then theoretically after a certain time, i.e. when the pressure has been fully built up in the monitoring line 40, a set nominal pressure of 6 bar is present at the pressure sensors 89, 90 arranged in the monitoring line on the outlet side. However, since such a pneumatic system has a certain amount of leakage, the pressure present at the outlet is approximately 25% less than the set nominal pressure. If the amount of the pressure difference between the inlet 84 and the outlet 85 is less than 25%, a correct clamping of the pallet is identified, while a defective clamping of the pallet is identified in the case of a pressure difference between the inlet 84 and the outlet 85 of more than 25%. However, in the present case, the system is designed so that the pressure difference between the inlet 84 and the outlet 85 when the clamping bolt is not present reaches approximately 50%.

[0071] It can thus be determined that in the case of a correct clamping and locking of a pallet with clamping pins, at an inlet pressure of 6 bar, there is a pressure of the order of magnitude of approximately 4.5-5.5 bar at the two pressure sensors 89, 90 arranged at the outlet side in the monitoring line, whereas in the absence of a clamping pin or its incorrect locking, there is a pressure of less than 3 bar. This difference is nevertheless large enough to be able to determine with the aid of the evaluation electronics whether the pallet is correctly clamped. While the difference, in particular the pressure measured at the outlet, should preferably be classified within the maximum range in the case of new chucks, it may be somewhat smaller in the case of long-used chucks, wherein measurements have shown that even after more than 50,000 clamping procedures the difference is still large enough to be able to reliably distinguish whether a pallet is correctly clamped.

[0072] Figure 8 A further example of an embodiment of the invention is shown, namely a clamping device 53 having a clamping base 54 comprising four chucks 59, 60, 61, 62 for clamping a workpiece carrier 74. Each clamping pin 59, 60, 61, 62 is designed according to the example of embodiment explained previously, for which reason the respective chuck 59, 60, 61, 62 will not be described in detail hereinafter. The workpiece carrier 74 has on its bottom side four clamping pins 75, 76, 77, 78 arranged corresponding to the chucks 59, 60, 61, 62. During clamping on the clamping device 53, the bottom side of the workpiece carrier 74 rests on the Z support of the respective chuck 59, 60, 61, 62. In the clamping base 54, the monitoring line again extends from the coupling 57 arranged at the inlet side to the coupling 56 arranged at the outlet side.

[0073] The four valve devices of the four cartridges 59, 60, 61, 62 are connected in series with one another, i.e. the outlet of the first valve device is connected to the inlet of the second valve device, the outlet of the second valve device is connected to the inlet of the third valve device, and the outlet of the third valve device is connected to the inlet of the fourth valve device. The inlet of the first valve device is connected to the inlet of the monitoring line, while the outlet of the fourth valve device is connected to the outlet of the monitoring line. The inlet of the monitoring line is thus connected to the outlet of the monitoring line via the four valve devices connected in series with one another. A further line branches off from the monitoring line between the inlet of the monitoring line and the first valve device, and a fourth control line branches off from this line in turn, which leads to a control opening arranged in the insertion area of ​​the respective cartridge 59, 60, 61, 62. All control openings are therefore connected in parallel with one another.

[0074] Fig. 9A further element of the second chuck arrangement 81 with the previously explained clamping device 53 is shown by means of a simplified diagram. The further element is likewise a peripheral part of the processing machine on which the clamping device 52 is used or a part belonging to the periphery of the processing machine. In this example, it is assumed that the processing machine is used, such as has been done by means of Figure 7 The elements and lines provided at the machine side therefore have the same reference numerals as in the first chuck arrangement 80 . The clamping device 53 comprises four chucks 59 , 60 , 61 , 62 which are arranged on a clamping base 54 .

[0075] The monitoring line from the inlet 82 through the clamping device 53 to the outlet 83 is provided at the inlet side with the reference numeral 40. Individual subsections of the monitoring line are provided with the reference numerals 40a-40e.

[0076] In addition to the clamping device 53, the second cartridge arrangement 81 also comprises a first pressure sensor 88 connected to the monitoring line 40 at the inlet side and two further pressure sensors 89, 90 connected to the monitoring line 40e at the outlet side. In each case, each of the four cartridges 59, 60, 61, 62 has an actuating piston loaded by means of a compression spring and a valve arrangement 69, 70, 71, 72. Likewise, at least one control bore 7 emerges in each case into the receiving opening of the respective cartridge 59, 60, 61, 62, but preferably each cartridge 59, 60, 61, 62 has two control bores 7. As further elements of the cartridge arrangement 81, a pressure regulator 86, a control element 87, a throttle valve 91 and a pressure line 92 can likewise be seen, via which the space below the respective actuating piston 11 can be pressurized. A pressure regulator 86 on the inlet side is connected to the inlet 82 via a line 84, while a line 85 leads from the outlet 83 to two pressure sensors 89, 90 arranged in parallel at the outlet side. For a clearer representation, further elements such as evaluation electronics are not represented. The pressure sensor 88 on the inlet side and the two pressure sensors 89, 90 connected to the monitoring lines at the outlet side are both connected to the evaluation electronics.

[0077] The monitoring line 40 is connected to the control openings 7 of all the chucks 59, 60, 61, 62. For this purpose, a connecting line 40a branches off from the monitoring line 40 after the inlet 82, wherein the connecting line 40a is also regarded as part of the monitoring line 40. Control lines 64, 65, 66, 67 again branch off from this connecting line 40a in each case in the region of the respective chuck 59, 60, 61, 62, which lead to the control opening 7 or to the control opening of the associated chuck 59, 60, 61, 62. As can be seen with the aid of the first chuck 59, a line also leads from the respective control line 64 into the space above the actuating piston 11 of the chuck 59. The monitoring line 40 can thus also be used in order to load the actuating piston 11 downwards in the direction of its locking position, which can be used in particular for re-tightening the respective locking piston 11 after clamping the clamping bolt. It is important, however, that no compressed air is delivered into the re-tightening space as long as the chuck remains open. If the clamping bolt is not received in each chuck 59, 60, 61, 62, sufficient pressure can be built up in the monitoring line 40 and all actuating pistons 11 can also be re-tightened simultaneously by introducing compressed air. In the opposite case, an already existing "re-tightening line" (such as is usually already present with a universal clamping device) can also be used to check the presence of the clamping bolt. For this purpose, the chucks 59, 60, 61, 62 must be designed according to the invention and the corresponding lines must be connected to the re-tightening line.

[0078] It can also be seen that the four valve devices 69, 70, 71, 72 are connected in series with one another and that the inlet 82 of the monitoring line 40 is connected to the outlet 83 of the monitoring line 40 via the four valve devices 69, 70, 71, 72. For this purpose, the connecting line 40a is connected to the inlet of the first valve device 69 in the region of the first cartridge 59. The outlet of the first valve device 69 is connected via the line 40b to the inlet of the second valve device 70, which is connected via the line 40c to the inlet of the third valve device 71. The outlet of the third valve device 71 is connected via the line 40d to the inlet of the fourth valve device 72. The line 40e leads from the outlet of the fourth valve device 72 (which is also regarded as part of the monitoring line 40) to the outlet 83.

[0079] The function of the chuck arrangement 81 with respect to monitoring the presence and correct clamping of the pallet is essentially the same as in the previously described example, with the difference that all chucks 59, 60, 61, 62 are monitored. Various variants are explained again below, with only partial reference to the reference numerals of the first chuck 59, since the four chucks are of identical design. In all variants it is assumed that the pressure space 27 arranged below the respective actuating piston 11 is not subject to overpressure.

[0080] Variant 1: No tray exists.

[0081] In this variant it is assumed that no pallet is placed on the clamping device 53. In the absence of a pallet, the clamping pins are also not received in any of the clamping discs 59, 60, 61, 62. In order to check whether the pallet is correctly clamped on the clamping device 53 by means of the four clamping pins, the monitoring line 40 is pneumatically subjected to an overpressure via the connecting line 84 at the inlet side. If the clamping pins are not received in any of the clamping discs 59, 60, 61, 62, the air flowing into the monitoring line 40 escapes to the atmosphere via the control opening 7 of the corresponding clamping disc 59. Since the mass of the air flowing into the monitoring line 40 is limited by the throttle valve 91 at the inlet side, if at least one of the clamping pins is not present, only a small overpressure is formed in the monitoring line 40, which in all cases is well below the limit value of approximately 4.5 bar defined for correct clamping. The pressure present at the two pressure sensors 89, 90 connected to the monitoring line 40e at the outlet side is therefore significantly less than the pressure of 6 bar set at the inlet side by means of the pressure regulator 86. If the actuating piston 11 of the corresponding chuck 50 is in the locked position, the corresponding valve body of the corresponding valve device 69, 70, 71, 72 is in the open position, but because the air flowing into the monitoring line 40 escapes via the control hole 7, the pressure sensors 89, 90 at the outlet side measure a pressure far below the set pressure of 6 bar. As mentioned above, the pressure measured at the outlet side depends on various further parameters. However, it is also important that, by means of the pressure measured at the outlet side, a clear distinction can be made between a correct clamping of the pallet and an incorrect clamping of the pallet or the absence of the chuck. In the case of such a clamping device 53, different states are also preferably identified by means of a test, and a pressure range is assigned to a given state. In all cases, in variant 1 the pressure prevailing at the two pressure sensors 89 , 90 can be detected by means of evaluation electronics (not shown in detail here) which does not correspond to the overpressure required for a secure clamping (at least 4.5 bar or 450 kPa).

[0082] Variant 2: A tray is present, but at least one clamping pin is not present

[0083] In this variant it is assumed that the pallet is located on the clamping device, but at least one clamping bolt is not present, so no clamping bolt is received in at least one clamping disk 59, 60, 61, 62. In this case as well, the introduced compressed air escapes via the control opening of the clamping disk in which no clamping bolt is received. Since the mass of the air flowing into the monitoring line 40 is limited by the throttle valve 91 at the inlet side, only a small overpressure is formed in the monitoring line 40 when no clamping bolt is present.

[0084] The throttle valve is dimensioned so that, in the event of the absence of a clamping bolt and correct locking of the chuck, the pressure at the outlet 83 is less than or equal to 2 bar.

[0085] Therefore, also in this case, the pressure measured by the two pressure sensors 89, 90 at the outlet side is less than approximately 2 bar, regardless of the position of the actuating piston 11 and the correspondingly associated valve means 69, 70, 71, 72. Therefore, the pressure present at the two pressure sensors 89, 90 detected by means of the evaluation electronics does not correspond to the overpressure required for a secure clamping.

[0086] Variant 3: The pallet is present with all clamping pins, but is not clamped correctly

[0087] In this variant, it is assumed that the pallet with four clamping bolts is located on the four chucks 59, 60, 61, 62 of the clamping device 53, and all four clamping bolts are received in the receiving openings of the corresponding chucks 59, 60, 61, 62. The control hole of the corresponding chuck is closed by the corresponding clamping bolt. However, as long as at least one actuating piston is not in the locking position, wherein for example the actuating piston 11 of the first chuck 59 is stuck, the associated valve device 69 occupies the shut-off position and blocks the passage in the monitoring line at the corresponding point. Because the four valve devices 69, 70, 71, 72 are connected in series with each other, again, at the two pressure sensors 89, 90 connected to the monitoring line 40 at the outlet side, there is a pressure that is much smaller than the inlet pressure of 6 bar set by means of the pressure regulator 86. If at least one of the four valve devices 69, 70, 71, 72 occupies the shut-off position, the pressure existing at the two pressure sensors 89, 90 corresponds essentially to the ambient pressure, but in all cases is lower than 2 bar. Therefore, it is detected by means of the evaluation electronics that a reliable clamping of the workpiece carrier has not yet taken place.

[0088] In the case where at least one of the actuating pistons 11 of the four chucks 59, 60, 61, 62 is already in the locked position before the pallet is placed on the clamping device 53 and its clamping pin is inserted into the receiving opening of the corresponding chuck 59, 60, 61, 62, the clamping pin at the chuck in the locked position cannot be fully inserted into the receiving opening, as previously described by means of Figure 7 (Variant 2) Already explained. In this case as well, it is recognized by means of the evaluation electronics that a secure clamping of the workpiece carrier has not yet taken place.

[0089] Variant 4: Correct clamping of the pallet in the chuck with the aid of all clamping pins.

[0090] In this variant it is assumed that the pallet is located on the clamping device 53 and that the four clamping bolts are clamped and correctly locked by means of the four chucks 59, 60, 61, 62. The actuating piston of the respective chuck is in its lower locking position, in which it presses the clamping member inwardly into the receiving opening. The clamping member abuts against the shoulder of the respective clamping bolt and the latter is pulled downwards together with the pallet with great force, so that the bottom side of the pallet is fixedly located on the raised Z-supports of the four chucks 59, 60, 61, 62 of the clamping device 53. All control holes 7 arranged in the insertion area of ​​the respective receiving opening are therefore tightly closed by the conical centering area of ​​the corresponding clamping bolt. Because the actuating pistons 11 of all four chucks 59, 60, 61, 62 are in the locking position, the two radial holes in the respective valve body are also connected to each other via the annular space of the internal insert ( Figure 6 ) and all four valve devices 69, 70, 71, 72 are in the open position. The inlet side 82 of the monitoring line 40 is therefore connected to its outlet side 83 via the four valve devices 69, 70, 71, 72.

[0091] Taking into account the leakage of the system, when the four clamping bolts are correctly locked, a pressure of the order of magnitude of approximately 4.5-5.5 bar prevails at the two pressure sensors 89 , 90 arranged at the outlet side in the monitoring lines and the evaluation electronics recognize the correct clamping of the pallet.

[0092] In summary, it can be said that in the case of correct clamping and locking of a pallet with four clamping bolts, in the case of an inlet pressure of 6 bar, there is a pressure of the order of magnitude of approximately 4.5-5.5 bar at the two pressure sensors 89, 90 arranged at the outlet side in the monitoring line, whereas in the case of the absence of at least one clamping bolt or at least one clamping bolt not correctly locked, there is a pressure of less than 2 bar. By means of this difference, it is possible to reliably identify with the aid of the evaluation electronics whether the pallet has been correctly clamped. Likewise, it can be mentioned again that in the case of correct clamping of the pallet, in the case of a new chuck, the pressure at the outlet can preferably be classified in the upper range, i.e. between approximately 5 and 5.5 bar, whereas after several thousand or tens of thousands of clamping procedures, it tends to be slightly lower and can be approximately 4.5 to 5 bar. However, in any case, the pressure present at the outlet side in the case of correct clamping of the pallet is still large enough to reliably determine that the pallet is also correctly clamped.

[0093] Furthermore, the compressed air fed into the monitoring line 40 can be used to clean the contact surfaces on the underside of the pallet and / or on the clamping pins by means of blowing. For this purpose, at least one valve must be provided, by means of which the compressed air introduced into the monitoring line 40 is deflected to the cleaning opening 8 ( Figure 1). Since the clamping systems designed according to the prior art usually already have a pneumatic coupling or a pneumatic connection for introducing compressed air for blowing off / cleaning the contact surface, existing processing machines can also be retrofitted relatively easily. In the case of clamping systems designed according to the prior art, the pneumatic coupling or a pneumatic connection is also usually arranged at the outlet side, which is connected to the outlet of one and / or the other pipeline.

[0094] It goes without saying that the above examples of embodiments are not decisive, but different embodiments are certainly possible within the scope of the invention. Thus, for example, instead of two control holes, a plurality of control holes differentiated therefrom can be provided for each chuck. Providing at least two control holes for each chuck has the advantage that an increased volume flow and thus a larger measurable ΔP is achieved when no clamping bolt is present.

[0095] Although only clamping systems with one or four chucks were explained previously, clamping systems with two, three, five or more chucks can of course also be designed according to the invention and the correct clamping of the pallet can be monitored.

[0096] Since the throttle valve is dimensioned so that the pressure at the outlet 83 is less than or equal to 2 bar in the absence of just one clamping bolt and with one or more cartridges correctly locked, the pressure measured on the outlet side is less than or equal to 2 bar in the absence of at least one clamping bolt. Regardless of the number of cartridges, the pressure measured upward on the outlet side is always less than or equal to 2 bar in the absence of at least one clamping bolt.

[0097] The following briefly summarizes the advantages of the chuck designed according to the present invention:

[0098] - in the case of a chuck designed according to the invention, the correct clamping of the pallet in the chuck can be reliably monitored;

[0099] - the absence of a clamping pin and therefore of a pallet can also be reliably detected;

[0100] In the case of a clamping device having a plurality of chucks for clamping a pallet having a plurality of clamping pegs, both the presence of all clamping pegs and their correct clamping can be reliably monitored;

[0101] a chuck designed according to the invention or a clamping device designed according to the invention is suitable for long-term use and functions in a stable manner over a long period of time;

[0102] - Relatively few mechanical parts need to be provided;

[0103] Existing processing machines can be retrofitted or equipped relatively easily and cost-effectively with a chuck designed according to the invention or with a clamping device designed according to the invention.

[0104] List of reference numerals:

[0105] 1. Chuck

[0106] 2. Clamping plate

[0107] 3.3a ​​Internal Z support / 3b External Z support

[0108] 4. Hollow cylindrical extension

[0109] 5. Receiving opening

[0110] 6. Insertion area (conical)

[0111] 7. Control hole

[0112] 8. Clean the hole

[0113] 9. Connectors

[0114] 10. Clamping device

[0115] 11. Actuating piston

[0116] 12. Clamping member (sphere)

[0117] 14.Compression spring

[0118] 15. Control pipeline

[0119] 16. Valve device

[0120] 17. Valve housing

[0121] 18. External part (valve housing)

[0122] 19. Internal part (valve housing)

[0123] 20. Clamping base

[0124] 21. Valve body

[0125] 22. Axial inlet hole

[0126] 23. First radial hole

[0127] 24. Second radial hole

[0128] 25. Axial outlet hole

[0129] 26. Re-tighten the pipeline

[0130] 27. Space below the actuating piston

[0131] 30. Ring Space

[0132] 31. Hole actuating piston

[0133] 32. Snap ring

[0134] 33. Seals

[0135] 34. Slotted cut

[0136] 35. Slotted cut

[0137] 40. Monitoring pipeline

[0138] 44. Dashed Line

[0139] 46. ​​Tray

[0140] 47. Clamping bolt

[0141] 48. Rear centering area

[0142] 49. Front part

[0143] 50. Shoulders

[0144] 53. Clamping device

[0145] 54. Clamping base

[0146] 56. Connection entrance

[0147] 57.Connection export

[0148] 59. First Chuck

[0149] 60. Second chuck

[0150] 61. Third Chuck

[0151] 62. The fourth chuck

[0152] 64.First control pipeline

[0153] 65. Second control pipeline

[0154] 66. Third control pipeline

[0155] 67.Fourth control pipeline

[0156] 69.First valve device

[0157] 70. Second valve device

[0158] 71. Third valve device

[0159] 72.Fourth valve device

[0160] 74. Workpiece carrier

[0161] 75.First clamping bolt

[0162] 76. Second clamping bolt

[0163] 77. Third clamping bolt

[0164] 78.Fourth clamping bolt

[0165] 80.First chuck arrangement structure

[0166] 81. Second chuck arrangement structure

[0167] 82. Entrance

[0168] 83. Export

[0169] 84.Connect pipeline inlet side

[0170] 85.Connect the pipeline outlet side

[0171] 86. Pressure regulator

[0172] 87. Control elements

[0173] 88. Pressure sensor inlet side

[0174] 89.First pressure sensor outlet side

[0175] 90. Second pressure sensor outlet side

[0176] 91. Throttle valve.

Claims

1. A chuck (1) for clamping a tray (46) having a clamping bolt (47), wherein the chuck (1) has a receiving opening (5) for the clamping bolt (47) and a clamping device (10), the clamping device (10) comprising a clamping member (12) for clamping the clamping bolt (47) in the receiving opening (5), characterized in that The chuck (1) has a monitoring line (40) which can be pneumatically acted and leads from an inlet (82) to an outlet (83), and the receiving opening (5) comprises a conical insertion area (6), into which at least one control hole (7) connected to the monitoring line (40) protrudes, the control hole being able to be closed by means of the clamping bolt (47) so that it can be checked by means of the monitoring line (40) whether the clamping bolt (47) is correctly received in the chuck (1), wherein the control hole is in fluid communication with the monitoring line between the inlet and the outlet, and wherein a first pressure sensor (88) is connected to the monitoring line (40) at the inlet side, and a second pressure sensor (89) and a third pressure sensor (90) are connected to the monitoring line (40) at the outlet side.

2. The chuck (1) according to claim 1, wherein the clamping device (10) comprises an actuating piston (11) displaceable between an initial position and a locking position for actuating the clamping member (12), characterized in that The chuck (1) comprises a valve device (16) arranged between the inlet (82) and the outlet (83) of the monitoring line (40), by means of which the flow of fluid through the monitoring line (40) can be varied depending on the position of the actuating piston (11).

3. The chuck (1) according to claim 2, characterized in that The valve device (16) comprises a valve housing (17) and a valve body (21) at least sectionally accommodated therein, wherein the valve housing (17) is displaceable relative to the valve body (21) or the valve body (21) is displaceable relative to the valve housing (17) between a closed position and an open position so as to change the flow of the fluid.

4. The chuck (1) according to claim 3, characterized in that The valve body (21) or the valve housing (17) is connected to the actuating piston (11) so that when the actuating piston (11) is correctly displaced into the locking position, the valve device (16) is in the open position, and when the actuating piston (11) is not correctly displaced into the locking position, the valve device (16) is in the closed position.

5. The chuck (1) according to claim 3 or 4, characterized in that The valve body (21) is arranged to be stationary, whereas the valve housing (17) is connected to the actuating piston (11) in a firmly bonded manner.

6. The chuck (1) according to claim 5, characterized in that The valve housing (17) comprises an outer part (18) and an inner part (19), wherein the outer part (18) is connected to the actuating piston (11) in a firmly bonded manner, and the inner part (19) is connected to the outer part (18) in an axial direction in a form-fitting manner, and wherein the inner part (19) is accommodated in the outer part (18) with radial play.

7. The chuck (3) according to claim 3 or 4, characterized in that An axial inlet hole (22) opens into the valve body (21) from the upper side and an axial outlet hole (25) opens into the valve body (21) from the bottom side, wherein the axial inlet hole (22) emerges into a first radial through hole (23), and wherein the axial outlet hole (25) emerges into a second radial through hole (24), and wherein the first radial through hole (23) extends over the second radial through hole (24), and wherein the inner part (19) of the valve housing (17) has an annular space (30) whose axial length corresponds at least to the distance between the two radial through holes (23, 24), and wherein the annular space (30) extends over the two radial holes (23, 24) when the actuating piston (11) is in its locked position.

8. The chuck (1) according to any one of claims 2 to 4, characterized in that: When the clamping bolt (47) is received in the receiving opening (5) of the chuck (1) and is correctly locked by means of the clamping device (10), the monitoring line (40) is continuously open between the inlet (82) and the outlet (83), but is closed to the atmosphere.

9. A clamping device (53) for clamping a pallet (74), the clamping device (53) having at least two chucks (59, 60, 61, 62) designed according to any one of claims 1 to 8, the clamping device (53) comprising a plurality of clamping pins (75, 76, 77, 78) corresponding to the number of the chucks (59, 60, 61, 62), characterized in that: The chucks (59, 60, 61, 62) are housed in a common clamping base (54), and the clamping base (54) has a pneumatically actuatable monitoring line (40) leading from an inlet (82) to an outlet (83), the monitoring line (40) being connected to all control holes (7) arranged in the region of the insertion tube of the respective chuck (59, 60, 61, 62).

10. A clamping device (53) according to claim 9, wherein each chuck (59, 60, 61, 62) comprises valve means (69, 70, 71, 72) by means of which the flow of fluid through the monitoring line (40) can be varied depending on the position of the respective actuating piston (11), characterized in that The valve devices (69, 70, 71, 72) are arranged between the inlet (82) and the outlet (83) of the monitoring line (40) and are connected in series with each other so that a passage exists between the inlet (82) and the outlet (83) of the monitoring line (40) only when all the actuating pistons (11) are correctly locked.

11. The clamping device according to claim 9 or 10, characterized in that: In the region of the respective chuck (59, 60, 61, 62), pneumatic refastening lines open into a refastening space arranged above the respective actuating piston (11), wherein each refastening line is directly or indirectly connected to the monitoring line (40).

12. The clamping device according to claim 9 or 10, characterized in that: When the clamping bolts (75, 76, 77, 78) are received in the receiving openings of each chuck (59, 60, 61, 62) and are correctly locked by means of the respective clamping means, the monitoring line (40) is continuously open between the inlet (82) and the outlet (83), but closed with respect to the atmosphere.

13. A chuck arrangement (81, 81) having a chuck (1) designed according to any one of claims 1 to 8 or a clamping device (53) designed according to any one of claims 9 to 12, wherein the chuck arrangement (80, 81) comprises an inlet line (84) which can be connected to a pneumatic pressure source and is connected to the inlet (40) of the monitoring line (40) passing through the clamping base, characterized in that The monitoring line (40) is connected to an outlet line (85) on the outlet side and the outlet line (85) is connected to at least one pressure sensor for detecting the pressure.

14. The chuck arrangement (80, 81) according to claim 13, characterized in that A throttle valve (91) which limits the amount of air flow is arranged in the inlet line (84), wherein the inlet line (84) is connected to a first pressure sensor (88), and the outlet line (85) is connected to a second pressure sensor (89) and a third pressure sensor (90) for detecting the pressure prevailing in the monitoring line (40) at the outlet side, and wherein the cartridge arrangement comprises evaluation electronics for recording and evaluating the pressures determined by means of the first pressure sensor (88), the second pressure sensor (89) and the third pressure sensor (90).

15. A method for detecting the clamping state of a pallet (74) clamped on a chuck arrangement (80, 81) according to claim 13 or 14, wherein the monitoring line (40) is connected to a pneumatic pressure source via the inlet line (84), and wherein at least one pressure sensor for detecting the pressure is arranged in the outlet line (85) connected to the monitoring line (40) at the outlet side, characterized in that The inlet line (84) is pressurized and after a predetermined time the pressure existing at the outlet (85) is measured and compared with the pressure measured or set at the inlet (84), and correct clamping of the pallet (74) is detected if the pressure difference between the inlet (84) and the outlet (85) is less than 25%, and / or defective clamping of the pallet (74) is detected if the pressure difference between the inlet (84) and the outlet (84) is more than 25%.

16. The method according to claim 15, wherein the outlet line (85) connected to the monitoring line (40) at the outlet side is connected to a second pressure sensor (89) and a third pressure sensor (90), characterized in that The inlet line (84) is pressurized and after a predetermined time the pressure in the inlet line (84) is measured and compared with the pressure measured by means of the second pressure sensor (89) and the third pressure sensor (90) arranged at the outlet side and, in the event that the measured pressure difference between the second pressure sensor (89) and the third pressure sensor (90) arranged at the outlet side is greater than 10%, an error message is output and / or defective clamping of the pallet (74) is detected.

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