Abstract:
The invention includes a clamping system for a workpiece on a measuring machine, with a multiple-jaw clamping chuck. A rotary drive rotates the multiple-jaw clamping chuck. The rotary drive includes a stator and a rotor. The multiple-jaw clamping chuck has a chuck body wherein the clamping jaws are radially movable for clamping a workpiece or loosening it from the clamping chuck, a flat spiral mounted rotating relative to the chuck body in positive engagement with the clamping jaws, and an outer rim rotating with respect to the stator. The flat spiral is firmly joined to the rotor of the rotary drive, but can turn relative to the chuck body in order to move the clamping jaws radially inward or outward. Using a coupling, a part of the clamping system can be secured so that the rotary drive takes on the function of adjusting the clamping jaws.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention is directed to a clamping system for a workpiece on a measuring machine, with a multiple-jaw clamping chuck and with a rotary drive provided for the rotation of the multiple-jaw clamping chuck, wherein the rotary drive comprises a stator and a rotor and wherein the multiple-jaw clamping chuck has a chuck body, in which the clamping jaws are radially movable for clamping a workpiece in the clamping chuck or loosening it from the clamping chuck, a flat spiral mounted so that it can rotate relative to the chuck body, being in positive engagement with the clamping jaws, and an outer rim able to rotate with respect to the stator. 
         [0003]    2. Discussion of the Related Art 
         [0004]    A measuring machine, on which a clamping system of the aforementioned kind is used, can be found for example in the company brochure “KLINGELNBERG P26/P40 Precision Measuring Centers” with the publication information “DE 05/2013”. On page 4 this describes a precision measuring center in which the measuring machine has a heavy-duty precision rotary table. This is designed as a measuring axis (C axis) and concentrically holds the workpieces being checked. In combination with three linear measuring axes: tangential (X axis), radial (Y axis) and vertical (Z axis), the precision measuring centers probe functional surfaces on gear teeth and general drive components in generator mode and verify them with utmost accuracy of measurement and reproduction. 
         [0005]    In the present P series of the applicant, to which the precision measuring centers P26 and P40 belong according to the aforementioned company brochure, there is the possibility of holding the workpieces by clamping between centers (shown in the company brochure on page 4), holding it in the clamping chuck (shown in the company brochure on page 12, left figure in the next to last row of figures) and direct placement of the workpiece on the rotary table, possibly with an adapted base (boom or faceplate). Direct placement is used in practice only for large workpieces. In a measuring machine as is partly visible in the aforementioned figure on page 12 of the company brochure there is no backstop, so that the clamping between centers does not occur in this machine. When it involves workpieces of low weight, a measuring of workpieces only set down in place is not recommended. Therefore, in the machine per page 12 of the company brochure the workpieces being measured are held in a clamping system with a multiple-jaw clamping chuck. Such a multiple-jaw clamping chuck is shown in the enclosed drawings in  FIGS. 7 and 8 , to which reference shall now be made. 
         [0006]    The multiple-jaw clamping chuck designated overall as  11 ′ is provided with an electrical rotary drive  12 ′ for rotation of the multiple-jaw clamping chuck. The rotary drive  12 ′ comprises a stator  12   a ′ and a rotor  12   b ′. Moreover, the multiple-jaw clamping chuck  11 ′ has a chuck body  14 ′. The chuck body  14 ′ is firmly joined to the rotor  12   b ′ internally. Jaws  16   a ′,  16   b ′ and  16   c ′ in the chuck body  14 ′ are moved radially in order to clamp a workpiece (not shown) in the multiple-jaw clamping chuck  10 ′ or to loosen it from the multiple-jaw clamping chuck  11 ′. A flat spiral  18 ′ is mounted with ability to rotate relative to the chuck body  14 ′ and in positive engagement with the jaws  16   a ′,  16   b ′ and  16   c ′. While the chuck body  14 ′ is held by one hand, the flat spiral  18 ′ is rotated to clamp or release a workpiece (not shown) by the other hand via an external rim  20 ′. The external rim  20 ′ is firmly arranged on the flat spiral  18 ′, for example, it is integrally formed therewith. By turning the flat spiral  18 ′ relative to the chuck body  14 ′, the clamping jaws  16   a ′,  16   b ′ and  16   c ′ are moved radially. The rotary drive  12 ′ serves to rotate the complete multiple-jaw clamping chuck  10 ′ including the clamped workpiece. The performance of the clamping process in this known clamping system is not comfortable, because the activating of the clamping system must be done with both hands. Accordingly, the operator has no hands free to hold the workpiece while clamping or loosening it. Furthermore, the known clamping system only handles a small range of clamping situations. Moreover, the operator has little control over the force exerted on the workpiece being clamped. What is more, the clamping jaws require many steps when the clamping range is large and the clamping diameter has to be set quickly and manually. 
         [0007]    The object of the invention is to ensure an easier handling of the clamping system and handle a broader range of clamping situations for a clamping system of the aforementioned kind. 
       SUMMARY OF THE INVENTION 
       [0008]    This object is achieved according to the invention, starting from a clamping system of the kind mentioned above, in that the flat spiral is firmly joined to the rotor of the rotary drive, but can turn relative to the chuck body in order to move the clamping jaws radially inward or outward, and with the help of a coupling a part of the clamping system can be secured during a clamping or releasing process so that the rotary drive takes on the function of adjusting the clamping jaws. 
         [0009]    As compared to a manually operated clamping system the clamping system of the invention, which is motorized, i.e., operated by the electrical rotary drive of the multiple-jaw clamping chuck, offers the following advantages:
       One or a few steps are needed in the clamping jaws when the clamping range is large enough, because the clamping diameter can be quickly set in motorized manner.   The setting of the clamping diameters can be done automatically by selecting the drawing number.   Comfortable single-hand operation, clamping by the press of a button.   The workpiece clamping force can be adjusted.   Easy automation is possible.       
 
         [0015]    These advantages are achieved because the invention involves a motorized clamping system, in which the electric rotary drive present any way in the C axis is used for the activation. The clamping function of the clamping system according to the invention is realized on the basis of standard technologies of a multiple-jaw clamping chuck, especially a three-jaw clamping chuck. With the help of a coupling, a part of the clamping system is secured during a clamping or loosening process, so that the drive unit takes on the function of the adjustment of the clamping jaws. The torque of the C axis rotary drive can be regulated with high precision. Thanks to this torque regulation, a regulating of the force of the workpiece clamping is possible. The direct coupling of the C axis rotary drive to the C axis remains intact in the clamping system of the invention. As a result, the C axis regulation is not influenced by the clamping system. 
         [0016]    Thanks to the use according to the invention of the electric rotary drive which is present any way and standard technology for the clamping system, an economically attractive solution is also achieved. 
         [0017]    In one embodiment of the clamping system according to the invention, the fixable part of the clamping system comprises the outer rim. The outer rim is joined to the chuck body in torque-proof manner. The chuck body can be coupled in frictional or positive manner by the other rim across the coupling to the stator of the rotary drive. Both coupling options allow the rotary drive to use the C axis in easy manner to fix a part of the clamping system with the help of the coupling during a clamping or loosening process, so that the rotary drive of the C axis takes on the function of the clamping jaw adjustment. This does not interrupt the direct coupling of the C axis/rotary drive to the C axis by the coupling, so that the C axis control as already mentioned is not affected by the clamping system according to the invention. 
         [0018]    In a further embodiment of the clamping system according to the invention, the outer rim is configured such that the chuck body can be coupled by friction to the stator of the rotary drive in the manner of a drum or disk brake. In this and in another embodiment of the clamping system according to the invention, in which the outer rim has a toothing and the coupling has a coupling lever with a toothing linked to the stator of the rotary drive, which can be brought into engagement with the toothing of the outer rim, the coupling is activated only by the press of a button. The clamping or loosening process then occurs with the aid of the electrical rotary drive of the multiple-jaw chuck. The chuck body is in fact joined to the outer rim in torque-proof manner and mechanically coupled via the coupling toothing and the coupling lever to the stator, so that the chuck body does not turn along while the rotor turns the flat spiral. When the coupling is not activated and the workpiece is clamped, the rotary drive serves as usual to rotate the complete multiple-jaw chuck, including the workpiece. 
         [0019]    In yet a further embodiment of the clamping system according to the invention, the chuck body is designed as a brake drum and the coupling has a clamping ring with brake shoes linked to the stator of the rotary drive, by which the chuck body can be coupled by friction to the stator of the rotary drive. This is an advantageous embodiment of a clamping system in which the chuck body can be coupled by friction with the stator of the rotary drive in the manner of a drum brake. 
         [0020]    In yet a further embodiment of the clamping system according to the invention, the outer rim is configured as a brake disk and the coupling has, as actuator, a caliper firmly connected to the stator of the rotary drive, which encloses the brake disk like pliers and carries brake linings, so that the chuck body can be coupled frictionally to the stator by pressing the brake linings against the brake disk. This is an advantageous embodiment of a clamping system in which the chuck body can be coupled frictionally to the stator of the rotary drive in the manner of a disk brake. 
         [0021]    In yet a further embodiment of the clamping system according to the invention, the chuck body can be coupled frictionally or by form fitting to the stator of the rotary drive with the help of a manually, electrically, pneumatically or hydraulically operated actuator. This enables, as already mentioned, the clamping by press of a button, and thus a comfortable single-hand operation of the clamping system as well as easy automation. 
     
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
         [0022]    Sample embodiments of the invention shall be described more closely in the following, making reference to the drawings. These show 
           [0023]      FIG. 1  a first embodiment of a motorized clamping system according to the invention in a partial sectional view, 
           [0024]      FIG. 2  the clamping system of  FIG. 1 , but in which besides a chuck body provided with an outer rim there is also shown a flat spiral in a partial sectional view, 
           [0025]      FIG. 3  the clamping system of  FIG. 2 , but with a clamped workpiece, 
           [0026]      FIG. 4  the clamping system of  FIG. 1  in a view from above, 
           [0027]      FIG. 5  a second embodiment of the motorized clamping system according to the invention, 
           [0028]      FIG. 6  a third embodiment of the motorized clamping system according to the invention, 
           [0029]      FIG. 7  a traditional three-jaw clamping chuck in a partial sectional view, and 
           [0030]      FIG. 8  the traditional three-jaw clamping chuck of  FIG. 7  in another partial sectional view. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    A first embodiment of a motorized clamping system according to the invention is shown in  FIG. 1  in a partial sectional view and in  FIG. 4  in a view from above and designated generally as  10 . A multiple-jaw clamping chuck  11 , being a three-jaw chuck in the case of the embodiment shown in  FIGS. 1 and 4 , is provided with an electrical rotary drive  12  for turning the multiple-jaw clamping chuck  11 . The rotary drive  12  comprises a stator  12   a  and a rotor  12   b . Furthermore, the multiple-jaw clamping chuck  11  has a chuck body  14 . The chuck body  14  is not connected firmly to the rotor  12   b  on the inside as is the chuck body  14 ′ in the traditional multiple-jaw clamping chuck  11 ′ of  FIGS. 7 and 8 , but rather can turn relative to the rotor  12   b . Clamping jaws  16   a ,  16   b  and  16   c  are radially movable in the chuck body  14  so as to clamp a workpiece  22  (shown in  FIG. 3 ) in the multiple-jaw clamping chuck  11  or loosen it from the multiple-jaw clamping chuck  11 . 
         [0032]    A flat spiral  18 , on which the chuck body  14  is rotationally mounted, if connected firmly on the inside to the rotor  12   b  or forms a single piece with the rotor  12   b  as in the representation of  FIG. 3 , yet continues to be able to turn relative to the chuck body. The flat spiral  18  engages with the clamping jaws  16   a ,  16   b  and  16   c  by positive engagement or positive coupling. Thanks to a rotation of the flat spiral  18  relative to the chuck body  14  brought about with the help of the electrical rotary drive  12 , the clamping jaws  16   a ,  16   b  and  16   c  are moved radially. However, the turning of the flat spiral  18  is not done manually, as in the traditional multiple-jaw clamping chuck  11 ′, but is motorized with the help of the electrical rotary drive  12 , which is the rotary drive of a measuring machine (not shown), in whose C axis the multiple-jaw clamping chuck  11  is arranged with the workpiece  22  being measured. The measurement on the workpiece  22  and the measurement layout correspond to those in a measuring machine according to the aforementioned company brochure “KLINGELNBERG P26/P40 precision measuring centers”. A rotary table of the measuring machine, which is designed as the measuring or C axis, holds the workpiece being checked in concentric fashion. 
         [0033]    In the embodiment shown in  FIGS. 1 and 4 , an outer rim  20  is integrally formed on the chuck body  14 , i.e., it forms a single piece with it. On its outer circumference the outer rim  20  does not have a knurling or the like to facilitate the manual activation of the outer rim  20 , but instead a toothing  24 , which is part of a coupling designated overall as  30 . With the help of the coupling  30 , a part of the clamping system  10  can be fixed during a clamping or loosening process, so that the electrical rotary drive of the measuring machine, being represented here by the stator  12   a  and the rotor  12   b , can take on the function of the clamping jaw adjustment. The fixable part of the clamping system  10  is the chuck body  14  with the outer rim  20 . The coupling  30  comprises a coupling lever  32  with a toothing  34 , spring-hinged to the stator  12   a  of the electrical rotary drive  12  on a support block  13 , which can engage in positive coupling manner with the toothing  24  of the outer rim  20 . The activating of the coupling lever  32  is done by a manually, electrically or pneumatically controlled actuator  36 . Thus, by means of the coupling  30 , the outer rim  20  and thus the chuck body  14  can be fixed on the stator  12   a , so that the electrical rotary drive  12  takes on the function of the clamping jaw adjustment by placing the flat spiral  18  in rotation relative to the chuck body  14 . In this way, the clamping jaws  16   a ,  16   b  and  16   c  are moved radially. Since the chuck body  14  is mechanically linked to the stator  12   a  across the coupling toothings  24  and  34  and the coupling lever  32 , the chuck body  14  does not rotate along when the rotor  12   b  turns the flat spiral  18 . When the coupling  30  is not activated and a workpiece  22  is clamped in the clamping jaws  16   a ,  16   b  and  16   c , the electrical rotary drive  12  serves to turn the multiple-jaw clamping chuck  11  along with the workpiece  22  in traditional fashion. The force acting upon the clamped workpiece  22  via the clamping jaws  16   a ,  16   b  and  16   c  is adjusted by controlling the torque of the electrical rotary drive  12 . The operation of the clamping system  10  can be done with one hand by pressing a button  38 , which controls the actuator  36 . The operator&#39;s other hand is free to hold the workpiece  22  while it is being clamped or released. 
         [0034]    In the representation in  FIG. 2  of the clamping system  10  of  FIG. 1 , besides the chuck body  14  provided with the outer rim  20  there is also shown the flat spiral  18  in a partial sectional view. The firm connection of the flat spiral  18  to the rotor  12   b  can be produced by a positive or material-bonded connection (the latter is shown in  FIG. 2 ). 
         [0035]      FIG. 5  shows a second embodiment of a motorized clamping system according to the invention, being generally designated as  110 . It differs from the clamping system  10  in that a coupling  130  couples the chuck body  14  to the stator  12   a  of the rotary drive  12  not by positive coupling through an outer rim, but instead couples the chuck body  14  frictionally to the stator  12   a  of the rotary drive  12 . For this purpose, the chuck body  14  with the outer rim is fashioned on the outside as a brake drum  120 . 
         [0036]    Furthermore, the coupling lever  32  present in the first embodiment is replaced by a clamping ring, designated overall as  132 . The clamping ring has two clamping ring segments  132   a  and  132   b . The clamping ring segments  132   a ,  132   b  each carry a brake shoe  134   a  and  134   b . The clamping ring segments  132   a ,  132   b  are each linked at one end  135   a  and  135   b  to a support block  113 , which is firmly mounted on the stator  12   a  like the support block  13  of the clamping system  10 , for example by means of a screw fastening. The latter is not shown in  FIG. 5 , but it is shown with the support block  13  of the clamping system  10  (for example, in  FIG. 1 ). The clamping ring segment  132   a  is linked at another end  135   c  to an actuator  136 . The actuator  136  can be a piston and cylinder unit, which is pneumatically, hydraulically or electromagnetically operated, like the actuator  36 . In  FIG. 5 , only one end of the actuator  136  can be seen. This end of the actuator  136  is linked to the end  135   c  of the clamping ring segment  132   a . When the actuator  136  is a piston and cylinder unit, the actuator  136  is linked at its other end, which cannot be seen in  FIG. 5 , by an end of a piston rod sticking out from the actuator  136  to the other end of the clamping ring segment  132   b , also not seen in  FIG. 5 . Thanks to an operating button, which also cannot be seen in  FIG. 5 , the actuator  136  of the clamping system  110  can be controlled like the actuator  36  of the clamping system  10 . When the actuator  136  is activated for clamping by the operating button, the piston rod is retracted into the actuator  136  and thereby clamps the brake shoes  134   a ,  134   b  firmly against the brake drum  120  with the help of the clamping ring  132 , so as to couple the chuck body  14  frictionally to the stator  12   a . Thus, the fixable part of the clamping system  110  here is the chuck body  14 , which is configured as the brake drum  120 . 
         [0037]      FIG. 6  shows a third embodiment of a motorized clamping system according to the invention, designated generally as  210 . It differs from the clamping system  110  of  FIG. 5  in that the chuck body  14  is configured not as a brake drum  120 , but instead carries a brake disk  140 . In other words, the outer rim  20  of the clamping system  10  in the case of the clamping system  110  is fashioned as a brake disk  140 . Moreover, the coupling  230  has as its actuator a caliper  213  firmly connected to the stator  12   a  of the rotary drive  12 . The caliper  213  encloses the brake disk  140  like pliers and carries brake linings  234   a ,  234   b , so that the chuck body  14  can be frictionally coupled to the stator  12   a  by pressing the brake linings  234   a ,  234   b  against the brake disk  140 . Thus, the fixable part of the clamping system  210  is the chuck body  14  with the brake disk  140  integrally formed therewith or firmly mounted on it. 
         [0038]    In the clamping system  110  of  FIG. 5  and the clamping system  210  of  FIG. 6 , the chuck body  14  can be coupled to the stator  12   a  of the rotary drive  12  by means of a manually, electrically, pneumatically or hydraulically operated actuator  136  or  236 , but by frictional coupling and not by positive coupling The actuator  236  is only suggested in the representation of  FIG. 6 . This involves the typical activating mechanism for the brake linings, which is arranged inside the caliper  213 . 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
           10 , Clamping system 
           11 ,  11 ′ Multiple-jaw clamping chuck 
           12 ,  12 ′ Rotary drive 
           12   a ,  12   a ′ Stator 
           12   b ,  12   b ′ Rotor 
           13  Support block 
           14 ,  14 ′ Chuck body 
           16   a ,  16   a ′ Clamping jaw 
           16   b ,  16   b ′ Clamping jaw 
           16   c ,  16   c ′ Clamping jaw 
           18 ,  18 ′ Flat spiral 
           20 ,  20 ′ Outer rim 
           22  Workpiece 
           24  Toothing 
           30  Coupling 
           32  Coupling lever 
           34  Toothing 
           36  Actuator 
           38  Button 
           110  Clamping system 
           113  Support block 
           120  Brake drum 
           130  Coupling 
           132  Clamping ring 
           132   a ,  132   b  Clamping ring segment 
           134   a ,  134   b  Brake shoe 
           135   a ,  135   b  End 
           136  Actuator 
           140  Brake disk 
           142  Brake caliper 
           210  Clamping system 
           230  Coupling 
           232  Caliper 
           234   a ,  234   b  Brake lining 
           236  Actuator