Abstract:
A replacement device for clamping heads comprises a plurality of clamping jaws and is provided with pivoting parts, which are pivotably mounted on a carrier. The pivoting parts extend essentially in the axial direction of said device and can engage in holes on the clamping jaws. A radially active force applying device pushes the pivoting parts outwards, causing the clamping jaws connected thereto to be pressed together. In this way, the clamping head can be used in a housing or a machine-tool.

Description:
FIELD OF APPLICATION AND PRIOR ART  
       [0001]     The invention relates to a replacement or changing device for clamping heads having several clamping jaws.  
         [0002]     DE 283 1140 A discloses a clamping jaw comprising a clamping head and a body. Such clamping jaws are characterized in that they can be very rapidly re-tooled. The body and clamping head are connected by a coupling. The clamping head comprises several clamping jaws linked by an elastomer. As a result of the elastomer, at least in the vicinity of the coupling, the clamping head can be compressed for connecting and disconnecting the coupling.  
         [0003]     The coupling between the body and the clamping head is usually formed by a radial projection. The connection and disconnection of the connecting coupling takes place through radial compression of the individual clamping jaws of the clamping head or by a tilting movement of the individual clamping jaws leading to disengagement of the radial coupling. For releasing the coupling use is made of a tool, which engages in axial recesses on the front face of the segments of the clamping head, such as is also described in DE 283 1140 A. This type of operation suffers from the disadvantage that it is not in accordance with the force distribution. If the elastomer between the clamping jaws of the clamping head is compressed, there is a superproportional increase in the force necessary for this, so that at the end of the process a great detail of force must be applied by an operator.  
         [0004]     This problem can be solved by the use of a gear system which is in accordance with this force distribution. De 10138343 A1 describes such a device, which is operated by a lever mechanism. Hydraulically or pneumatically operated devices are also known. It is common to all the known devices that they have pivoting parts, whose number is matched to the number of clamping jaws of the clamping head. These pivoting parts are directed radially and are mounted in tangentially directed shafts. The operating force necessary for pivoting purposes is initiated by a central tie bolt.  
         [0005]     As a result of the arrangement of the pivoting parts, the known replacement tools have very large radial dimensions and are usually much larger than the clamping head to be replaced. This makes difficult a use in machines having tools arranged around the machining spindles or where the spindles are closely juxtaposed. It is also necessary in some applications to as far as possible support the workpiece to be machined or to keep its extension length as small as possible. For this purpose the clamping head is constructed with an extended projecting part. This projecting part necessary for support purposes extends from the front face of the clamping head. The projecting part usually has a small diameter, so that there is an adequate collision free space for the tools required for machining. In such cases the clamping head can no longer be changed with the known changing devices, because the central arrangement of the tie bolt and the radial extension of the pivoting parts prevent a joining of the clamping head. In order to still enable replacement to take place, the pins necessary for operation are made extremely long. However, this unfavourably changes the leverage, so that the operating force increases enormously and can scarcely be manually provided.  
       Problem and Solution  
       [0006]     The problem of the invention is to provide a replacement device of the aforementioned type making it possible to avoid the problems of the prior art and in particular enabling the replacement of clamping heads with a projecting part, whilst simultaneously using little force, whilst also significantly reducing the radial construction space.  
         [0007]     This problem is solved by a replacement device having the features of claim  1 . Advantageous and preferred developments of the invention form the subject matter of further claims and are explained in greater detail hereinafter. By express reference the wording of the claims is made into part of the content of the description.  
         [0008]     The replacement or changing device has a carrier, which extends radially from a central axis, particularly a median longitudinal axis, of the replacement device with outer areas so as to project from the central axis. A bearing is provided for one pivoting part per clamping jaw at the outer areas or ends or carrier plates fixed thereto. The pivoting part has at least one and in certain circumstances two extending sections cooperating with a clamping jaw. With such a cooperation, which can for example be brought about by engagement in the clamping jaw, a radial force and a torque can be transmitted. If the pivoting part is pivoted about the bearing, the extending portions also pivot and radially are drawn closer together, particularly at their ends. Therefore, in per se known manner, they press together the clamping jaws, particularly at the remote end, in order to produce or release the aforementioned coupling. According to the invention for pivoting the pivoting parts a force application device is provided, whose action direction is substantially radial, it acting on a point on the pivoting parts for pivoting purposes having an axial spacing from the bearing and to the extending portions. In particular, the force application device can act substantially radially outwards.  
         [0009]     Thus, other than in the prior art, the pivoting parts can at least partly and advantageously largely run in the axial direction. Radially within the bearing for the pivoting parts can be formed a free space, into which can for example project a projecting part of a clamping head. As a result the lever length or leverage by which the force application device acts on the pivoting parts, can be chosen independently of the radial extension.  
         [0010]     The force application part acting on the pivoting parts can, according to a development of the invention, have a lever system. This can in particular be a toggle lever system for an advantageous force distribution and a type of automatic locking. Thus, an essentially axially acting operating force can be converted into the force acting radially on the pivoting parts. The replacement device can have a lever carrier, which is axially movable relative to the carrier or the two parts are movable relative to one another. There is at least one lever per pivoting part on the lever carrier and is operatively connected to the pivoting part, for example is mounted in rotary manner by a screw coupling or the like. The lever is at an inclined angle to the radial direction or central axis. Advantageously it can slope in the same direction towards the pivoting part in which the lever carrier moves towards the carrier during the relative movement of the two parts. For example said angle can be approximately 30 to 60ø, preferably approximately 45ø. It is particularly advantageous if the ratio between the axial operating path and the radial operating path for the lever at the end of pivoting is at a maximum, because then the force ratio is also very large. The lever end angle is advantageously virtually 90ø.  
         [0011]     If the lever carrier and carrier are moved relative to one another and in particular towards one another, as a result of its bearing both on the lever carrier and on the pivoting part, the lever is rotated radially in an ever shallower angle, so that it presses the pivoting parts outwards. This for example makes it possible for a type of self-locking to so-to-speak over-press the lever beyond the radial direction and it is locked in this position by the opposing force. This is then a typical toggle lever system.  
         [0012]     In an alternative development of the invention the force application device can have a wedge or key gear. In this case part of the wedge gear is placed on a pivoting part and another part is placed on a wedge gear carrier, which is axially relatively movable with respect to the carrier. The parts of the wedge gear can cooperate in such a way that during the relative movement there is a pivoting of the pivoting parts. To the wedge gear carrier is for example fixed a conical part, which acts against correspondingly cooperating opposing parts on the pivoting parts, particularly with a corresponding bevel, the taper of the cone being in the direction of the relative movement between carrier and wedge gear carrier. During the relative movement the cone presses apart the pivoting parts.  
         [0013]     Advantageously the pivoting parts are substantially axially directed, i.e. directed parallel to the central axis. This permits a radially relatively confined arrangement. It makes it possible to construct the replacement device somewhat longer in the axial direction so that in the case of a limited radial extension an adequate leverage can be exerted on the extending portions and therefore the clamping jaws.  
         [0014]     An application point of the force application device on the pivoting parts can have roughly the same radial spacing from the central axis as the bearing of the pivoting parts on the carrier. Alternatively said point can be displaced radially inwards or radially outwards. Moreover, in conjunction with the radial acting force application device or the force distribution produced by it the pivoting characteristics of the pivoting parts can be adjusted or positively influenced in a desired manner. Thus, it is possible for said high force to be reached precisely at the end of the pivoting of the pivoting parts, when the force to be applied to the clamping jaws is at a maximum.  
         [0015]     It is also possible within the scope of the invention to construct the pivoting parts with a radially inwardly directed bend on which the force application device acts. This can also influence the force distribution.  
         [0016]     To achieve very low operating forces in the case of minimum construction sizes, the bearing of a pivoting part on the carrier or a carrier plate fixed thereto can be located at an axial end region of the pivoting part. An application point of the force application device on the pivoting part can be axially far removed therefrom, in particular roughly at the other end region.  
         [0017]     The carrier and bearing of the pivoting parts are advantageously located on those sides of the replacement device which are directed towards the clamping head. This makes it possible to displace the fulcrum of the pivoting parts, which is also the fulcrum of the clamping jaws, as close as possible towards the said clamping jaws. As a result the clamping jaws of the clamping head can be particularly advantageously compressed, namely particularly at the remote end, which is intended to engage in the coupling of the body or the machine tool.  
         [0018]     As a function of the size of the replacement device, it can be advantageous if an extending portion runs in its longitudinal extension or the imaginary continuation of the longitudinal direction through the bearing of the pivoting parts on the carrier. This makes it possible to create a very large free inner space for clamping heads with a projecting part. However, this can be varied as a function of whether the replacement device is to be provided for clamping heads with a very large projecting part or with a minimum radial extension. The longitudinal extension can run past radially inside or outside.  
         [0019]     The outer area of the carrier can be constructed as a projecting arm. In particular, for this purpose the carrier can be constructed in one piece and in a roughly radial form. The outer area of the carrier can be constructed as a projecting arm, to whose sides are in each case fixed a carrier plate close to the end. These carrier plates are angular and can outwardly cover part of the replacement device. To these carrier plates are fixed bearing pins, advantageously roughly at right angles to the radial extension of the projecting arms of the carrier. A pivoting part can be mounted between two carrier plates. Through the fixed connection of the carrier plates to the carrier or its projecting arms, a fixed bearing for the pivoting parts on the carrier is obtained.  
         [0020]     A pivoting part can for example be constructed in such a way that it has a U-section extending in its longitudinal direction and which is open towards the central axis of the replacement device. The at least one extending portion is fixed to the base, particularly to the inside of the U-section. Advantageously the extending portion extends over the entire length of the U-section as an integral part, for example as a cylindrical pin. Thus, the extending portion can essentially take over the force transmission between the force application device and the clamping jaw.  
         [0021]     In particular, the extending portion should extend at least up to the area where the force application device acts on the pivoting part, which particularly adequately permits force transmission. It is possible for the force application device to act directly on the extending portion.  
         [0022]     To produce the relative movement between carrier and a further carrier on which the force application device acts, particularly the aforementioned lever carrier or wedge gear carrier, it is possible to link the two carriers by means of a guide pin or force transmission pin running along the central axis. One of the two carriers is firmly connected to the pin, whereas the other is mounted in axially movable manner thereon. Advantageously the guide pin is fixed to the carrier and projects over and beyond the force application device carrier, particularly away from the clamping head. Thus, an operating device can so-to-speak easily engage on the carrier, for example in that it engages both on the force application device carrier and on the guide pin extending over and beyond the same and brings about a relative movement between the two, for operating the replacement device. For this purpose the guide pin can be terminally provided with a thread onto which is screwed a corresponding thread on the operating device. On further screwing thereon, it presses against the carrier of the force application device and consequently brings about a relative movement of both parts. Alternatively lever systems or the like can be used, such as are in particular known from DE 101 38 343 A.  
         [0023]     These and further features can be gathered from the claims, description and drawings and individual features, both singly or in the form of subcombinations, can be implemented in an embodiment of the invention and in other fields and can represent advantageous, independently protectable constructions for which protection is claimed here. The subdivision of the application into individual sections and the subheadings in no way restrict the general validity of the statements made thereunder. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     Embodiments of the invention are described in greater detail hereinafter relative to the attached drawings, wherein show:  
         [0025]      FIG. 1 A  partial representation of an inventive replacement device with a view of the interior.  
         [0026]      FIG. 2 A  lateral partial section through the replacement device of  FIG. 1 .  
         [0027]      FIG. 3  An outside view of a complete inventive replacement device on a clamping head in the unoperated position.  
         [0028]      FIG. 4 A  lateral partial section through the arrangement of  FIG. 3 .  
         [0029]      FIG. 5  The arrangement according to  FIG. 3  in the operated state with compressed clamping head.  
         [0030]      FIG. 6  An alternative construction of an operating device for an inventive replacement device in a lateral partial section. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0031]      FIG. 1  shows a replacement or changing device  11  according to the invention. This is constructed for a clamping head having three clamping jaws, as becomes clear from the representation in FIGS.  3  to  5 . To a carrier  13  having three projecting arms are fixed to the sides of said arms carrier plates  15 , for example by welding or screwing. The carrier plates  15  are in each case provided between two adjacent arms of carrier  13 , as is more particularly shown in  FIG. 3 .  
         [0032]     On the carrier plates  15  are provided pivot bearings  17 . In a simple case these are formed by holes in the carrier plate  15 , into which engage projecting shafts or the like. On the pivot bearings  17  are mounted pivoting parts  20  comprising an elongated U-section  21 , which is open towards the centre or the central axis shown in broken line form in  FIG. 2 . In the U-sections  21  of pivoting parts  20  are in each case inserted two rods  23  as extending portions and are advantageously fixed therein. They clearly project downwards beyond the U-sections  21  for engagement in the clamping jaws of the chuck. The fixing of the rods  23  to the pivot bearings  17  or the construction of this arrangement can be readily carried out by the expert. At the other end of the pivoting parts  20  is in each case provided a lever bearing, particularly as a through shaft or the like. A lever  31  is arranged in articulated manner thereon. In turn it is placed in articulated manner on a lever carrier  33 , whose outer contour is similar to carrier  13 . Like the latter it has three arms, a lever  31  being mounted on each arm.  
         [0033]     A guide pin  35  is fixed or integrally constructed on carrier  13  and projects through a corresponding opening in lever carrier  33  and projects somewhat beyond the same. This projecting length can differ as a function of the construction and further reference will be made thereto hereinafter.  
         [0034]      FIG. 2  shows the pivoting parts  20  in an at least partly pivoted position. The original, unoperated position  23 ′ in which the rods  23  are roughly parallel to the central axis is shown in broken line form.  
         [0035]      FIG. 3  shows a finished replacement device  11  in the unoperated state and is attached to a clamping head  40 . The latter is essentially constructed like a conventional clamping head, as described hereinbefore. It has three clamping jaws  41 , having in each case two front face holes  42 . Clamping jaws  41  are connected to rubber joints  43 , as is also known from the prior art. In the lower area the clamping jaws  41  have a circumferential groove  45  beneath which there is a circumferential projection  46 . Thus, the clamping jaws  41  or the clamping head  40  engage in the corresponding coupling of a tie rod or the like in a body or machine tool. It can also be seen that projecting parts  48  are constructed on the clamping head  40  radially inside the front face holes  42 .  
         [0036]     In  FIG. 3 , compared with  FIG. 2 , it can be gathered that the spacing between carrier  13  and lever carrier  31  is relatively large in the unoperated state.  
         [0037]     From the partial section of  FIG. 4  in the unoperated or starting state, it can be seen that here the rods  23  are parallel to the central axis shown in broken line form. The levers  31  project roughly in an angle of 45ø to the radial direction and therefore also to the central axis. As a result of the set back carrier  13  and the relatively widely outwardly positioned pivoting parts  20  or U-sections  21  and rods  23 , a large clearance is obtained, where there is adequate space for the projecting part  48  of clamping head  40 . The angled carrier plates  15  can be used for twisting-resistant guidance of the lever carrier  33  during relative movement with respect to carrier  13 .  
         [0038]     In this construction the guide rod  35  can have an external thread  36 , on which is mounted a handwheel  50  having an internal thread  52  matching the external thread  36 . The underside of handwheel  50  engages on lever carrier  33 .  
         [0039]      FIG. 5  shows how the handwheel  50  is screwed onto the guide pin  35 , where it presses the lever carrier  33  against carrier  13 . This leads to the change apparent from comparing  FIGS. 4 and 2 . Lever  31  is pivoted or drawn up and presses pivoting part  20  radially outwards. The latter pivots about pivot bearing  17 , so that the rods  23  projecting over U-section  21  or pivot bearing  17  are rotated radially inwards with the end thereof. In the maximum pivoted position shown in  FIG. 5 , lever carrier  33  can be moved still further towards the carrier  13 . The point at which the levers  31  are mounted on the lever carrier  33  can axially move past the lever bearing  30 . It is axially closer to carrier  13 . This corresponds to the toggle lever principle, in which the toggle lever arrangement is so-to-speak overpressed and comes into a stable position. No further force then has to be applied by the operating device.  
         [0040]     Alternatively to the bearing of rods  23  shown in  FIG. 2  and which is precisely at the height of pivot bearing  17 , it is possible for the rods  23  to run past the same radially inwards or radially outwards. The attainable advantages can be of a differing nature. For example, the pivoting movement of rods  23  from the broken line position  23 ′ shown in  FIG. 2  can be influenced.  
         [0041]      FIG. 6  shows a further replacement device  111 , which is attached to a known clamping head  40 . With the exception of the operating device, the replacement device  111  is constructed in a substantially identical manner to what has been described hereinbefore. The operating device is here a folding grip  155 , which has a gripping tray  157  provided with an attachment  158 . Attachment  158  engages on the top of carrier plates  115 . A folding part  159  is pivotably mounted on a bearing  160 .  
         [0042]     Guide pin  135  projecting from carrier  113  is connected to the gripping tray  157  and passes through a correspondingly large recess in folding part  159 . With the portion to the left of bearing  160 , folding part  159  is applied to the top of lever carrier  133 . If folding part  159  is pressed counterclockwise against the gripping tray  157 , then the latter, via guide pin  135  retains the carrier  113  whereas the lever carrier  133  is pressed downwards and against the same. Thus, once again the aforementioned rotation of lever  131  takes place and consequently a pivoting of pivoting parts  120  for compressing the clamping jaws  41  of clamping head  40 .