Abstract:
The invention relates to a balancing or measuring adapter ( 1 ) for clamping a component ( 2 ) on a rotating machine element of a balancing or measuring machine, which has a main body ( 4, 5 ) with a receiving opening ( 6 ) for the component ( 2 ) to be clamped, a collet chuck ( 11 ) arranged inside the main body ( 4, 5 ) with clamping tongues ( 26 ) for centrally clamping the component ( 2 ) and an actuator ( 12 ) axially adjustable between a clamp position and a release position for actuating the collet chuck ( 11 ). The collet chuck ( 11 ) is arranged inside the main body ( 4, 5 ) so as to be axially moveable such that, upon a displacement of the actuator ( 12 ) from the release position into the clamp position, in a first clamping phase the clamping tongues ( 26 ) of the collet chuck ( 11 ) move radially outwards, firstly to a front chucking area ( 27 ) allocated to the component ( 2 ) to be clamped, and that in a second clamping phase, the clamping tongues ( 26 ) move radially outwards with an axial movement inside the main body ( 4, 5 ) to a rear chucking area ( 28 ) allocated to the main body ( 4, 5 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to a balancing or measuring adapter and to a balancing or measuring machine having such a balancing or measuring adapter. 
     BACKGROUND OF THE INVENTION 
     Such balancing or measuring adapters are used for clamping a rotating component onto a balancing or measuring machine. A balancing machine having a balancing adapter of the type in question is known from DE 299 80 181. It contains a main body having a centered receiving opening for the component to be clamped and a claw actuating unit, movable relative to the main body, for a collet chuck. In this known design, the collet chuck is fixedly mounted on the main body and is not movable axially relative thereto. The clamping tongues of the collet chuck are therefore moved only radially when the claw actuating unit is displaced axially, and therefore the axial retraction travel is limited. 
     SUMMARY OF THE INVENTION 
     Some embodiments of the invention address the issue of creating a balancing or measuring adapter that enables a precisely positioned and reproducible reception and holding of a component to be clamped, with an enlarged retraction travel. 
     Expedient improvements and advantageous embodiments of the invention are also disclosed. 
     In the balancing or measuring adapter according to the invention, the collet chuck is arranged so as to be movable axially inside the main body such that, during a displacement of the actuating element from the release position into the clamping position, the clamping tongues of the collet chuck first move radially outward, during a first clamping phase, on a front clamping region associated with the component to be clamped, and during a second clamping phase, the clamping tongues move with an axial movement inside the main body and radially outward on a second clamping region associated with the main body. Thereby the clamping tongues of the collet chuck can first pivot at their outer, free ends and engage with a corresponding clamping groove on the inner side of a depression of the component to be clamped, while the rear clamping regions of the clamping tongues do not undergo a radial movement. Only during a further displacement of the actuating element into the clamping position do the clamping tongues also undergo an axial movement inside the main body and are also pressed radially outward on a rear clamping region. An enlarged axial retraction travel inside the main body [can] be achieved via this additional axial movement. 
     The actuating element expediently has a first outer conical surface associated with the front clamping region of the clamping tongues, and at least one second conical surface associated with the rear clamping region of the clamping tongues, the second conical surface being arranged offset axially relative to the first conical surface such that the first conical surface initially engages with the clamping tongues of the collet chuck during a displacement of the actuating element into the clamping position, and later the second conical surface engages with the clamping tongue of the collet chuck. 
     In an advantageous embodiment, the clamping tongues have a first inner clamping surface and a second inner clamping surface for contact with the first conical surface and the second conical surface, respectively, of the actuating element. The actuating element can additionally have a third conical surface adjoining the second conical surface, for contact with a third inner clamping surface of the clamping tongues, the third conical surface of the actuating element and the third conical surfaces of the clamping tongues having a lower inclination relative to the central axis of the main body than the second conical surface of the actuating element and the second conical surfaces of the clamping tongues. This has the effect that the clamping tongues initially have a large clamping travel with lesser clamping force and then have a smaller clamping travel with greater clamping force. A conical contact surface for contact with a conical inner clamping surface of the main body is preferably provided on the outer side of the rear clamping region of the clamping tongues. 
     In a favorable embodiment, the clamping tongues are formed integrally with a sleeve-like socket. The integral formation reduces the number of parts that are movable relative to one another and thereby a uniform mass distribution during the clamping process can be achieved. Rear slots, which are aligned with front axial slots between the clamping tongues and are open toward the front slots and closed to the rear, can be arranged in the socket. Thereby the elasticity of the collet chuck itself can be used for the radial return movement. No separate return elements are necessary. The rear slots are preferably wider than the front slots. Thereby the clamping tongues are very flexible and pliable in the rear region. 
     The collet chuck can be inserted into a recess in the main body and is supported at its lower end on a pressure disk impinged upon by compression springs. The collet chuck can be secured against inadvertently dropping out by radial pins in the main body. 
     The clamping tongues are designed to be relatively elongated in the front region, in order to be able to compensate for irregularities such as concentricity errors on the clamping surfaces. Thereby an axial elasticity can be achieved. In particular, the length of the front region of the collet chuck is greater than the diameter of the collet chuck. 
     In order to reduce the friction during the axial movement of the collet chuck inside the main body, the collet chuck can be arranged so as to be axially movable in the main body, for example by a bearing ring furnished with rolling elements. 
     The rolling elements can be radially prestressed, so that play-free guidance results. 
     The invention further relates to a balancing or measuring machine containing a balancing or measuring adapter having the above-described features. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional details and advantages of the invention emerge from the following description of a preferred embodiment with reference to the drawing. In the drawing: 
         FIG. 1 : shows a longitudinal section of a balancing or measuring adapter in a release position; 
         FIG. 2 : shows a longitudinal section of a balancing or measuring adapter from  FIG. 1  in an intermediate position; 
         FIG. 3 : shows a longitudinal section of a balancing or measuring adapter from  FIG. 1  in a clamping position; and 
         FIG. 4 : shows a collet chuck in a perspective view. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The balancing or measuring adapter  1  shown in different clamping positions in  FIGS. 1-3  is conceived for clamping a rotating component  2  on a balancing or measuring machine. Centered, highly precise and repeatable holding of the component  2  to be balanced or measured is of particular importance in such machines. The balancing or measuring adapter  1  contains a main body, which can be inserted into the drive spindle of the balancing or measuring machine for example, and which consists in the illustrated embodiment of a hollow cylindrical upper part  4  furnished with a flange  3  and a lower part  5  screwed onto the upper part. The main body can be mounted on the upper side of the drive spindle by means of the flange  3 , for example. 
     The upper part  4  has an upper receiving opening  6  for a shaft  7  of the component  2  to be clamped and a lower passage region  8  with conical inner clamping surfaces  9 . The component  2  can be a tool holder for a drilling, milling or grinding tool, a rotor or some other machine part to be balanced or measured. The shaft  7  is shaped conically and can have a polygonal, circular or other suitable cross section. The receiving opening  6  of the upper part  4  is correspondingly conical and has an inner contour matched to the cross section of the shaft  7 . A bearing bushing  10  with multiple rolling elements arranged in a cage can be inserted into the receiving opening  6  of the upper part  4 . Thereby the introduction of the shaft  7  into the upper part  4  of the main body can be facilitated. A collet chuck  11  and an actuating element  12  coaxial with the collet chuck are arranged in the main body, composed of the upper part  4  and the lower part  5 , in order to actuate the collet chuck  11 . 
     The actuating element  12  contains a lower rod-like guidance region  13  and an upper actuating head  14  with a first outer conical surface  15  in the upper part and two adjoining second and third outer conical surfaces  16  and  17  having different inclinations in the lower part. The actuating head  14  of the actuating element  12  engages at its upper part with a recess  18  in the shaft  7  of the component  2  to be clamped. In the embodiment shown, the first and second conical surfaces  15  and  16  have an inclination of 45° and the third conical surface  17  has an inclination of 4° relative to the center axis of the main body. The actuating element  12  is guided movably in the lower part  5  of the main body by the rod-like guidance region  13  by means of a bearing sleeve  19  provided with rolling elements. The bearing sleeve  19  is inserted into the central passage hole  20  in the lower part  5 . The rolling elements can be radially prestressed so that play-free guidance results. A piston  21  is mounted at the end of the rod-shaped guidance region  13  pointing downward relative to the lower part  5 . 
     Compression springs  22  that are visible in  FIGS. 2 and 3  are tensioned between the piston  21  and the lower part  5 . For stable retention, the compression springs  22  are inserted into blind holes, not visible, in the lower part  5  and in the piston  21 . The actuating element  12  is pressed by these compression springs  22  into the clamping position shown in  FIG. 3 . By displacing the piston  21  against the force of the compression springs  22 , the actuating element  12  can be pushed via an intermediate position shown in  FIG. 2  into the release position shown in  FIG. 1 . For this purpose, the piston  21  can be movably arranged, sealed via a radial seal  23 , in the drive spindle of the balancing or measuring machine and can be impinged upon from the lower side with compressed air. 
     The collet chuck  11 , shown separately in  FIG. 4 , has a sleeve-like socket  24  and a plurality of radially resilient clamping tongues  26  separated from one another by axial slots  25  and having a front clamping region  27  associated with the component  2  to be clamped and a rear clamping region  28  associated with the main body. The two clamping regions  27  and  28  are designed as thickened parts of the clamping tongues  26 . Rear slots  29 , which are open toward the front slots  25  and closed toward the rear end of the socket  24 , are arranged in the sleeve-like socket  24  of the collet chuck  11  and are also aligned with the front slots  25 . The rear slots  29 , transitioning into the front slots  25 , have a larger width than the front slots  25 . An external annular groove  30  is introduced into the rear end of the socket  23 . 
     The front clamping regions  27  facing the component  2  to be clamped have first inner conical clamping surfaces  31  for contact with the first outer conical surface  15  on the actuating head  14  of the actuating element  12 . First outer clamping surfaces  32  for contact with an inner clamping surface  33  of a clamping groove  34  arranged on the inner side of the recess  18  are also provided on the front clamping regions  27 . Successive conical second and third clamping surfaces  35  and  36  for contact with the second and third conical surfaces  16  and  17  of the actuating element  12  are located on the inner side of the rear clamping regions  28 . Corresponding to the second and third conical surfaces  16  and  17 , the second and third conical clamping surfaces  35  and  36  are inclined differently and have an angle of 45° and 4°, respectively, relative to the central axis in the illustrated embodiment. A conical contact surface  37  for contacting the conical inner clamping surface  9  on the inner side of the upper part  4  is provided on the outer side of the rear clamping regions  28 . 
     The collet chuck  11  is inserted via the annular socket  24  into a corresponding recess  38  of the lower part  5  and rests at its lower end on a pressure disc  40  pushed upward by compression springs  39 . A bearing ring  41  having a plurality of rolling elements arranged inside a cage for guiding the collet chuck  11  inside the recess  38  is arranged in the annular groove  30  at the lower end of the collet chuck  11 . These rolling elements can also be radially prestressed so that play-free guidance results. Inwardly protruding radial pins  43  for engagement with the lower slots  29  of the collet chuck  11  are inserted into radial bores  42  in the lower part  5 . Thereby the collet chuck  11  is axially secured inside the main body and the collet chuck  11  can be prevented from inadvertently falling out. The radially arranged pins  43  can be secured by axial threaded studs  44 . 
     The operation of the above-described balancing or measuring adapter will be explained below with reference to  FIGS. 1-3 . 
     The balancing adapter  1  is shown in a release position in  FIG. 1 . The actuating element  12  is pressed upward by means of the piston  21  impinged upon by compressed air or some other pressure medium. In the illustrated release position, the thickened portions  27  of the resilient clamping tongues  26  of the collet chuck  11  contact a first cylindrical region  45  of the actuating head  14  underneath the first conical surface  15 , and contact a second cylindrical surface  46  underneath the second conical surface  16  in the region of the rear thickened portion  28 . In the first cylindrical region  45 , the actuating head  14  has a smaller diameter than in a third cylindrical region  47  above the first conical surface  15 . Thereby the front clamping regions  27  of the collet chuck  11  are tilted radially inward out of the clamping groove  34  and release the component  2  for removal from or insertion into the balancing adapter  1 . 
     If the force acting from below on the piston  21  decreases, the actuating element  12  is pressed downward via the compression springs  22  tensioned between the lower part  5  and the piston  21 . Thereby the front clamping regions  27  at the front, free ends of the resilient clamping tongues  26  of the collet chuck  11 , which are engaged with the recess  18  of the component  2  to be clamped, slide on their inner conical clamping surfaces  31  along the first conical surface  15  of the actuating head  14 , whereby the front ends of the resilient clamping tongues  26  are pressed radially outward into the clamping groove  34  on the inner side of the component  2 . In a first clamping phase, only the front clamping regions  27  at the front, free ends of the resilient clamping tongues  26  are pressed radially outward until the second conical surface  16  of the actuating head  14  comes into contact with the conical clamping surfaces  35  of the collet chuck  11 . As the axial displacement of the actuating element  12  increases, the rear clamping regions  28  are also pressed radially outward in a second clamping phase, and the collet chuck  11  carries out an axial movement against the force of the compression springs  39  due to the contact of the conical contact surface  37  with the conical inner clamping surface  9  of the upper part  4 . 
     During movement of the rear clamping regions  28  along the 45°-angled conical surface  16 , the clamping tongues  26  of the collet chuck  11  carry out a long clamping travel with a small clamping force. When the conical clamping surfaces  36  of the collet chuck  11  come into contact with the 4°-angled third conical surface  17  during further axial movement of the actuating element  12 , a greater clamping force is then produced with a smaller clamping travel. The third conical surface  17  is arranged in the axial direction in such a manner that a movement of the rear clamping region  28  of the clamping tongues  26  along this surface and thus a clamping with greater force takes place only when the clamping tongues  26  are located with their front clamping region  27  in the cylindrical region  47  above the first conical surface  15  of the actuating element  12 . In the second and third clamping phases, the collet chuck  11  is displaced axially inside the main body against the force of the compression springs  39 . 
     By applying pressure to the piston  21 , the release process can take place in the opposite manner, wherein the actuating head  14  comes into contact with the component  2  at its upper end face in the final phase of the release stroke and presses the component out of the receiving opening  18  of the main body. Thereby the component  2  can be simply removed. 
     The invention is not limited to the embodiment described above and illustrated in the drawings. Thus individual clamping phases can also overlap in part. In addition, the clamping system can be used analogously also for clamping processes in which the radial clamping movement progresses from the outside to the inside.