Abstract:
A changing device for shaft and hub connections, comprising a shaft end, a hub part surrounding the shaft end, and a conical clamping bushing disposed therebetween. There is also provided a mechanism for retaining the clamping bushing on the end of the shaft in a way so that it cannot be lost, and at the same time serves to initiate biaxial displacement of the clamping bushing in relation to the end of the shaft. This permits assembling and dismantling of the hub part, whereby all other parts of the shaft and hub connection can remain mounted on the end of the shaft. This leads to particularly short tool changing times.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Ser. No. 08/942,959 filed Oct. 2, 1997 corresponding to U.S. Pat. No. 6,056,473. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a changing device for shaft and hub connections, including a shaft end, a hub surrounding the shaft end, and a bushing disposed in between for radially clamping the hub. 
     2. The Prior Art 
     These types of changing devices for shaft and hub connections are known, for example from “Taschenbuch für den Maschinenbau” [Handbook of Mechanical Engineering] (of DUBBEL, 18 th  edition, G25, illustration 33f). 
     When the hub is to be changed, however, the drawback is that a safety nut and a safety ring have to be completely removed so that the hub can be pulled off. This leads to costly additional work steps and prolongs the tool changing time. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to develop a changing device for shaft and hub connections of the above type, which permits quick changes of hubs with plain cylindrical bores, while all other parts of the shaft and hub connection remain mounted on the end of the shaft. Furthermore, the device ensures a safe transmission of forces and torques between the shaft and hub, and a precise repeatability of the axial position of the hub relative to the shaft. When the shaft and hub connection is released or clamped, the friction between the components moving in relation to each other is kept as low as possible. Furthermore, it is an object of the invention to permit the location of a shaft bearing close to the face of the hub which is opposite to the side of the shaft end. It is necessary to locate the shaft bearing next to the hub in order to transmit the radial forces generated by the operation of the machine directly from the hub into the shaft and to the shaft bearing, thereby minimizing any elastic deflection of the shaft which might reduce the precision of the rolling process in the machine. 
     According to the invention, there is provided a conical bushing between the end of the shaft and the hub, and means for safely retaining the bushing on the end of the shaft which at the same time provide an axial displacement of the bushing relative the end of the shaft in both directions. The outside diameter of the means for safely retaining the bushing is at least slightly smaller than the inside diameter of the hub, and these means are located on the side of the hub which points towards the end of the shaft. Axial displacement in both directions is initiated hydraulically so that the shaft and hub connection can be safely clamped and released and the hub can be quickly changed. Furthermore, the axial movement of the bushing during the clamping action presses the hub axially against a shoulder on the shaft which leads to an enhanced adjustment of the hub with regard to its axial position and its face runout. 
     In another object of the invention for safely retaining the clamping bushing and simultaneously initiating an axial displacement, there is provided a clamping pin rigidly mounted on the end of the shaft, and a nut screwed on to the clamping pin. In this way, the inside step of the bushing engages an intermediate space formed by an outside step of the clamping pin and the nut, to preserve the axial play of the bushing. Thus, a very simple and favorably priced engineering solution is provided with a flawless function. 
     It is useful if the nut and the outer step are each provided with circular grooves on their sides facing the inside step. Each nut and step displaceably receives a sealing ring and a pressure ring, so that the clamping pin and the nut each have means for building up pressure in the grooves. In this way, an axial displacement of the bushing can be easily and reliably initiated by the nut and the circular step, and the pressure rings inserted in their grooves. 
     In another useful embodiment of the invention, a fitted ring is provided between the end of the shaft and the clamping pin. The clamping pin can be fitted into the end of the shaft as required, and the required axial path of displacement of the bushing leading to radial clamping of the hub part can be preadjusted. 
     According to the invention, there is also provided means for safely retaining the bushing so that it cannot be lost, while at the same time biaxially displacing the bushing relative to the end of the shaft. The means for safely retaining the bushing are at least slightly smaller than the inside diameter of the hub part with respect to their spatial width perpendicular to the end of the shaft. The means for safely retaining the bushing are designed in the form of a part permanently mounted on the end of the shaft, and a receiving part movably connected with the part for a double-acting axial support. A means for transmitting an axial component of motion of the receiving part to the axial support is provided, and simultaneously transmitted to the bushing. This assures quick change of the hub part, and a safe clamping of the shaft and hub connection as well. Furthermore, there are comparatively low frictional forces as the changing device is being actuated, and the bushing is only moved axially, which provides a flawless adjustment of the part. 
     In a further advantageous object of the invention, the receiving part is rotatably connected via an inside thread with the outside thread of the part permanently mounted on the end of the shaft. In this way, there is a biaxial displacement of the bushing in a very easy and reliable way, and very precise paths of displacement can be adjusted. 
     The invention also provides that the double-acting support on the receiving part is axially fixed, and the biaxial displacement of the receiving part is transmitted to the bushing or an additional part fastened on the bushing. It is very advantageous if the double-acting support is fixed via a shaft nut against a step of the receiving part. This leads to a simple and safe axial securing of the support, and reliable further transmission of an axial component of motion of the receiving part. 
     In a highly useful embodiment of the invention, provision is made for a sealing ring between the double-acting axial support and the shaft nut, using radial sealing elements. This leads to increased protection of the double-acting axial support and thus a longer useful life. 
     If the part permanently mounted on the end of the shaft has a flange or step corresponding with a circular cavity of the end of the shaft, a reliable and space-saving connection of the part can be provided, permanently mounted on the shaft end with the end of the shaft, and axial securement of the part can be provided in an easy manner. 
     Additional axial guidance of the receiving part can be easily provided if the part, permanently mounted on the end of the shaft, has a cylindrical section corresponding with an inside diameter of the receiving part. 
     To easily actuate the alternative changing device, the receiving part can have a nut-shaped end or, alternatively, a cavity-like recess on the face side. 
     According to an advantageous embodiment of both alternative embodiments of the invention, the bushing is provided with a conical inside zone and the end of the shaft is conical, so that the conical inside zone corresponds with the conical end of the shaft. In this way, the outside diameter of the bushing can be designed cylindrically, which leads to a design of the hub part that is simpler, and which simplifies the adjustment of the hub part. 
     Advantageously, the bushing is provided with longitudinal slots, which provides good radial deformability. Moreover, the longitudinal slots are cast in an elastic sealing material in order to prevent any penetration of dust, water, dirt or the like. 
     The changing devices of the invention can be used very advantageously in connection with floating bearings of hub parts. However, the changing devices according to the invention are also useful in connection with double-sided bearings of the hub part. In this case, it is advantageous if the bushing has zones with a cylindrical surface having a diameter smaller than the inside diameter of the hub part. Thus, the hub part can be easily pushed over the bushing without the risk of damaging the smaller cylindrical outer surface serving as the bearing seat. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention. 
     In the drawings, wherein similar reference characters denote similar elements throughout the several views: 
     FIG. 1 shows a longitudinal cross section through the line I—I in FIG. 2 of a hydraulically operated changing device according to the invention; 
     FIG. 2 shows a front view of part of the changing device, specifically the clamping bushing of FIG. 1, whereby only the part is represented; 
     FIG. 3 shows a longitudinal cross section through a mechanical changing device according to the invention; 
     FIG. 4 shows a longitudinal cross section through a mechanical changing device according to the invention, in connection with a double-sided bearing; and 
     FIG. 5 shows a longitudinal cross section through a hydraulically operated changing device with a double-sided bearing according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, the right-hand side shows a conical shaft end  10  surrounded by a hub part  20 . Hub part  20  rests against a step  100  of shaft end  10  and may be, for example a profile-shaping straightening roll or comparable tool, which has to be changed as quickly as possible at low expenditure. Changing device  1  according to the invention permits a quick and simple dismantling of hub part  20 , on the one hand, and provides a safe and secure support of hub part  20  on shaft end  10 . As shown, changing device  1  consists substantially of a clamping bushing  30 , a clamping pin  40 , and a clamping nut  50 . As mentioned before, changing device  1  provides a greatly reduced friction of its parts moving relative to each other, i.e., in the present case clamping bushing  30 , clamping pin  40  and clamping nut  50 . In order to explain the mode of operation of changing device  1  of the invention, the following description describes how the parts are mounted for easier understanding. 
     The parts shown in FIG. 1 are substantially rotation-symmetric. On its right side, clamping pin  40  has an outside thread  404   b  joined at the left by a step  403 , extending all around. Prior to assembly, a fitted ring  80  is first pushed over the right outside thread  404   b  up to step  403  extending all around. With fitted ring  80 , it is possible to pre-adjust the required axial path of displacement of clamping bushing  30 , which provides a radial clamping of hub part  20 . Clamping pin  40  is subsequently completely screwed with its right outside thread  404   b  into a mating threaded blind-end bore  101  of conical shaft end  10 . FIG. 1 shows, furthermore, that within the zone of step  403  extending circumferentially, clamping pin  40  has a groove  4030  extending all around, the groove being open toward the left end of clamping pin  40 . On the bottom of circular groove  4030 , provision is made for a sealing ring  60   b.  A pressure ring  70   b  is placed on top of sealing ring  60   b.  Circular step  403  is joined by a second shaft step  405 , whose outside diameter is distinctly smaller than circular step  403  and slightly larger than the right-hand outside thread  404   b  of clamping pin  40 . Following the second shaft stop  405 , provision is made for a left outside thread  404   a,  the circumference of which approximately corresponds with the right outside thread  404   b.  The left outside thread  404   a  is followed by a short end piece of clamping pin  40 , which may be designed in the form of a multi-edged or hex nut in order to facilitate screwing of clamping pin  40  into shaft end  10 . 
     FIG. 1 shows that clamping bushing  30  basically has the shape of a can having its bottom and lid missing. Across about ⅔ of its length, starting from the right end, clamping bushing  30  has a conically tapering inside zone  304  corresponding with conical shaft end  10 . Conical inside zone  304  is followed by a cylindrical inside zone  305  having a width or bore only slightly larger than the one of circular step  403  of clamping pin  40 . Following the cylindrical inside zone  305 , provision is made for a step  303  extending all around, the latter in turn being followed by a cylindrical inside zone  306 . The latter has approximately the same diameter as cylindrical inside zone  305 . However, the inside diameter of inside step  303  is only slightly larger than the outside diameter of the second shaft stop  405  of clamping pin  40 . It will be shown later that this is required in order to permit a smooth axial reciprocation of clamping bushing  30  on shaft end  10 , and to minimize the frictional forces between clamping bushing  30  and clamping pin  40 . 
     Furthermore, FIG. 1 shows that starting from its right-hand end, clamping bushing  30  has a substantially cylindrical outer contour. Only in the zone of the left cylindrical inside zone  306  is provision made for a conical outer zone or surface  307 , tapering toward the left end of clamping bushing  30 , so that hub part  20  can be later pushed more easily over clamping bushing  30 . 
     FIGS. 1 and 2, furthermore, show that clamping bushing  30  has longitudinal slots  301  uniformly distributed over its circumference. Within the zone of inside step  303  of the clamping bushing, their slots change into the axial bores  302 . Clamping bushing  30  is circumferentially divided by the longitudinal slots  301  into clamping wing sections  308 , which can be radially expanded outwardly, which, as explained herein below, is required for a flawless radial clamping effect of clamping bushing  30 . Axial bores  302  serve only to reduce the notch effect. Following assembly, the longitudinal slots  301  can be cast in elastic sealing compound in order to prevent the penetration of dust or the like. 
     As mentioned above, when the changing device is assembled, clamping pin  40  is first tightly screwed into conical shaft end  10 . Subsequently, clamping bushing or collet  30  is pushed over clamping pin  40  on shaft end  10  from the left side. After clamping bushing  30  has been completely pushed over clamping pin  40  and shaft end  10 , clamping nut  50  is then screwed to the left outer thread  404   a  of clamping pin  40  until it rests against the second shaft step  405 . The maximum outer dimensions of clamping nut  50 , which, for example, may be a multi-edge nut, are slightly smaller than the inside diameter of the cylindrical inside zone  306 , which now surrounds about half of clamping nut  50 . In this way, an axial movement of clamping bushing  30  is not obstructed by the outside dimensions of clamping nut  50 . 
     The width of clamping nut  50  conforms to approximately the width of step  403  of the clamping pin extending circumferentially so that clamping nut  50  also has sufficient space for circular groove  503 , with the opening thereof being directed toward the inside step  303  of clamping bushing  30  and being approximately aligned with groove  4030 . As in circular groove  4030 , there is provided both a sealing ring  60   a  and pressure ring  70   a  in circular groove  503 . 
     In FIG. 1, after clamping nut  50  has been installed as described above, changing device  1  forms a clamping system which is closed within itself and rigidly connected with shaft end  10 . Its axial path of displacement S is limited by clamping nut  50  and step  403  of clamping pin  40 , and remains available only to inside step  303  of clamping bushing  30 . As opposed to what has been stated above, changing device  1  according to the invention can be screwed to shaft end  10  by means of clamping pin  40  also in the form of a pre-assembled unit comprised of clamping pin  40 , clamping bushing  30  and clamping nut  50 . 
     FIG. 1 shows changing device  1  in the “clamped” operating condition. In this condition, circular groove  503  is acted upon by oil pressure via a hydraulic nipple  501  of clamping nut  50 . Through a hydraulic duct  5010 , pressure build-up is effected on sealing ring  60   a  and thus also on pressure ring  70   a  downstream, whereby pressure ring  70   a  is pressed against the left side  3030   a  of inside step  303  of clamping bushing  30 , attempting to push the latter as far as possible in the direction of conical shaft end  10 . Through longitudinal slots  301  of clamping bushing  30 , it is now possible for clamping wings  308  to spread radially outwardly in the direction of shaft end  10  in proportion to the axial path of displacement S, which results in a clamping effect between clamping bushing  30  and hub part  20 , on the one hand, and shaft end  10  on the other hand. This clamping effect is substantial, so that changing device  1  is suitable for transmitting high torque, as well as radial and axial forces between the shaft and the hub even without interconnecting a fitted spring. 
     To insure safe clamping, a small gap has to be provided between right side  3030   b  of step  303  and circular step  403  of clamping pin  40 , when the changing device is in the clamping condition, as shown in FIG.  1 . This gap can be adjusted by means of fitted ring  80 , which has to be ground to the required thickness. Furthermore, it is necessary to make sure that in the “clamped” operating mode, clamping bushing  30  can be displaced as far as possible to the right in the direction of shaft end  10 . For this reason, provision is made for a vent  402  in clamping pin  40 , which, upon actuation of a venting screw  4020 , releases vent ducts  4021 , so that pressure ring  70   b,  which still may project from groove  4030 , is capable of yielding smoothly to the right, in the direction of the bottom of the groove. It has to be noted here that hub part  20 , which prior to clamping is loosely pushed onto clamping bushing  30 , is forced, in a defined way, against step  100  of shaft end  10  by the movement of clamping bushing  30  to the right. This represents an important adjustment advantage. 
     When the changing device is to be changed from operating mode “clamp” to operating mode “released”, the procedure is as follows: 
     Oil is supplied via a hydraulic nipple  401  of clamping pin  40  and received by sealing ring  60   b  via a hydraulic duct  4010 . Similar to the way the “clamping” mode worked in groove  503 , oil pressure now builds up in circular groove  4030 , and acts on pressure ring  70   b  via sealing ring  60   b.  Pressure ring  70   b  is thereby pressed in the axial direction to the left, out of groove  4030 , and thereby acts directly on the right side  3030   b  of inside step  303 , causing the latter to be displaced to the left. Together with the displacement of inside step  303 , the entire clamping bushing  30  is simultaneously forced axially to the left as well. Due to the concentricity, clamping wings  308  again move radially inward, returning to their starting positions, which finally cancels the clamping effect between the participating components (shaft end  10 , clamping bushing  30 , hub part  20 ). FIG. 1 shows that the maximum axial displacement path S of clamping bushing  30  is limited in this connection by the right side of clamping nut  50 , the latter representing a stop for the left side  3030   a  of inside step  303 . Naturally, the release of clamping bushing  30  functions flawlessly only if provision is also made for a vent  502  of circular groove  503  in this case, which, upon actuation of a vent screw  5020 , releases a vent duct  5021 , so that pressure ring  70   a,  which may still project, is capable of yielding without problems to the left in the direction of the bottom of the groove. Since the inside diameter  3031  (FIG. 2) of inside step  303  is slightly larger than the outside diameter of the second shaft step  405  of clamping pin  40 , then a slight axial displacement of clamping bushing  30  is not obstructed. 
     Hub part  20  can thus be pulled without any problem from clamping bushing  30  to the left, and thus from shaft end  10  and replaced by another hub part. It has to be noted that a suitable fit is maintained between the outside diameter of clamping bushing  30  and the inside diameter of hub part  20 . When changing device  1  is in the released condition, this arrangement permits an easy axial displacement of hub part  20  on clamping bushing  30 . 
     As described above, clamping pin  40 , clamping bushing  30  and clamping nut  50  form a so-called closed system, which remains connected with shaft end  10  both in the “released” and “clamped” modes, wherein there is only a slight axial play remaining available to clamping bushing  30 . This play can be used to clamp and release hub part  20 . Thus, it is possible for a quick and simple “overhead” assembly and dismantling of hub part  20 . It is also noted that when bushing  30  is clamped and released, it executes a pure axial displacement S, without rotation. No frictional forces occur between clamping bushing  30  and clamping pin  40  or clamping nut  50  and pressure rings  70 . This leads to a very reliable mode of operation of changing device  1 . 
     Referring to FIG. 3, there is shown an alternative embodiment consisting of a changing device  2  according to the invention. As opposed to the first alternative of FIG. 1, which is operated hydraulically, this embodiment is actuated mechanically. The parts shown in FIG. 3 are substantially rotationally symmetric as well, whereby changing device  2  substantially consists of a threaded bolt  24 , a threaded bushing  25 , a clamping bushing  23 , a sleeve-like retaining ring  26 , a shaft nut  27 , and a double-acting axial bearing  29 . As explained in greater detail below, these parts cooperate with a conical shaft end  22  and a hub part  21  so that a rapid and safe clamping of hub part  21  on shaft end  22 , and also an easy release of hub part  21  can be accomplished any time. Moreover, when changing device  2  is clamped, hub part  21  is pressed, in a defined way, to the right against a step  220  of shaft end  22 . 
     On the left side, threaded bolt  24  has an outside thread  243 , and at its right end, a flange  241  with through extending bores for screws  242 . To assemble changing device  2 , threaded bolt  24  with its flange  241  is first inserted in a circular hole  221  of the conical shaft end  22  and fastened by means of screws  242 . Subsequently, clamping bushing  23  is pushed over the conical shaft end  22 . FIG. 3 shows that in this case too, clamping bushing  23  has on its outside a cylindrical surface, and on its inside a conical inside surface  234  extending over about ⅔ of its length, its inside zone  234  corresponding with the concentricity of shaft end  22 . Furthermore, there are also provided longitudinal slots  231 , comparable to the slots of clamping bushing  30  shown in FIG. 1, in order to permit a radial spreading of clamping bushing  23  and thus a clamping effect. Clamping bushing  23 , furthermore, has an inside step  232  extending around its left front third, the inside diameter of the step approximately corresponding to the diameter of the circular hole  221  of shaft end  22 . In addition, at its left end, clamping bushing  23  has a plane surface  233 . 
     Threaded bushing  25  is provided with an inside thread  254 , which can be screwed to the outside thread  243  of threaded bolt  24 . On the right side, inside thread  254  is followed by a slightly larger inside diameter  257 . 
     Furthermore, at its right-hand side on the outside, threaded bushing  25  has a step  255  with sealing elements  256 , whereby the outside diameters of the elements approximately correspond with the inside diameter of inside step  232 . Double-action axial bearing  29  is pushed onto threaded bushing  25  up to step  255 , the bearing having a center ring  291  and two lateral rings  292 . The outside diameter of center ring  291  is preferably slightly smaller than the inside diameter of clamping bushing  23  surrounding the ring. A sealing ring  28  is mounted later for sealing. Double-action axial bearing  29  and sealing ring  28  are subsequently secured by means of shaft nut  27  which, via an outside thread  253  of threaded bushing  25 , is screwed to the latter. It is shown, furthermore, that threaded bushing  25  adjoining outside thread  253  is a nut- or hex-shaped end  251 , in which provision is made for a connection  252  for lubricating ducts  2520 . These lubricating ducts may later serve for lubricating double-action axial bearing  29 . 
     Finally, retaining ring  26  has to be screwed on to clamping bushing  23 . Retaining ring  26  has a flange  262  which, when compared to the right side of retaining ring  26 , is slightly recessed to the left, thus forming a right step  263  having an outside diameter approximately corresponding with the outside diameter of center ring  291  of double-action axial bearing  29 . 
     Retaining ring  26  is thus pushed over threaded bushing  25  until the right-hand step  263  abuts the left side  2912  of center ring  291 . Subsequently, retaining ring  26  is screwed on to the face  233  of clamping bushing  23  by means of screws  260 . It is important that after retaining ring  26  has been screwed on, center ring  291  is inserted without play between inside step  232  of clamping bushing  23 , on the one hand, and the right hand step  263  of the retaining ring, on the other hand, so that axial forces can be transmitted free of play. For this purpose, a minimum gap has to remain available between face  233  of clamping bushing  23  and flange  262  of retaining ring  26 . 
     FIG. 3 shows that after changing device  2  has been assembled, threaded bushing  25  and the parts mounted on this bushing form a unit which, when changing device  2  is actuated, executes an axial displacement S′, so that only threaded bolt  24  remains stationary in its position. This is explained in greater detail on the mode of operation of changing device  2 . 
     Assumed first that changing device  2  according to FIG. 3 is in the “clamped” operating mode. To release its clamping effect, i.e., the clamping effect of clamping bushing  23  versus hub part  21  and shaft end  22 , threaded bushing  25  has to be turned counterclockwise at its nut-like end  251  by means of a suitable tool. This puts threaded bushing  25  into an axial motion S′ and an axial flow of force starts to act on the right-hand step  263  of retaining ring  26 , starting from step  255  via center ring  291 . 
     Due to the fact that retaining ring  26  and clamping bushing  23  are screwed together, an axial movement takes place simultaneously to the left of clamping bushing  23 . The mode of operation is similar to the one described for FIG.  1 . The clamping wings of clamping bushing  23 , created by the longitudinal slots  231 , are relieved axially inwardly and thereby release the clamp. Hub part  21  can be easily pulled off to the left via clamping bushing  23  and flange  262  disposed and aligned adjacent to the bushing. Thereafter, a replacement hub part can be pushed onto bushing  23 . This change of parts can be helped by providing a tubular pull-off aid or tool  90 , which is applied to retaining ring  26  and aligned with clamping bushing  23 . This pull-off aid, of course, could be used also in connection with the changing device according to FIG.  1 . 
     Subsequent clamping of hub part  21  is accomplished by turning the nut-like end  251  to the right. This initiates an axial force via shaft nut  27 , which is transmitted by the right side  2911  of center ring  291  to inside step  232  of clamping bushing  23 . Analogous to the action of the clamping bushing described in connection with FIG. 1, a radially acting clamping effect is obtained through clamping bushing  23  in this case as well. 
     As the outside diameters of the lateral rings  292  are slightly smaller than inside bore  261  of the retaining ring, or the inside diameter of inside step  232 , a smooth rotary relative motion is possible between threaded bushing  25  and clamping bushing  23  and retaining ring  26 . Additional axial guidance of threaded bushing  25  is assured by its right-hand inside diameter  257 , the latter corresponding with a matching step of threaded bolt  24 , such step adjoining flange  241 . 
     It is clear that the “overhead” dismantling and mounting of hub part  21  is made possible also by the alternative embodiment of changing device  2  of the invention according to FIG. 3, whereby all elements of the changing device may remain on shaft end  22 . Changing hub part  21  is thus substantially facilitated and accelerated in this way. In the present case, nearly no frictional forces occur between clamping bushing  23  and threaded bushing  25  when clamping device  2  is actuated, except for negligible rolling friction of bearing  291 , so that clamping bushing  23  executes a purely (and defined) axial motion. 
     FIG. 4 shows in detail another application of the changing device of the invention. In the present case, the use of a mechanically actuated changing device  3  is shown. The mode of operation of this device is comparable to changing device  2  of FIG.  3 . Changing device  3  is used in the present case not for clamping a floatingly supported hub part but a hub part  33  supported in a double-sided way. Double-sided support is effected by a bearing stand  4  (indicated only) and a second bearing  5 . Double-sided bearings are required in cases where radial forces are particularly high. 
     As in the case of changing device  2  of FIG. 3, changing device  3  comprises a threaded bolt  34  screwed into a shaft end  32 , with a threaded bushing  35  with an inside thread  351  being rotatably connected with the bolt. Alternatively, threaded bushing  35  could be arranged with its inside thread  351  directly on the shaft and threaded bolt  34  omitted. A double-acting axial bearing  36  is secured on threaded bushing  35  by means of a shaft nut  37  against a step  350  of threaded bushing  35 . A clamping bushing  31  serves to radially clamp hub part  33 . Furthermore, there is also provided a sleeve-like retaining ring  38 , which presses the double-action axial bearing  36  against an inside step  310  of clamping bushing  31 , this step extending all around. This causes axial displacements S″, which are effected by turning threaded bushing  35 , to be transmitted to clamping bushing  31 . Within the range of its left end, retaining ring is provided with an outside thread, which is screwed into an inside thread at the left end of clamping bushing  31 . The left end of clamping bushing  31  has a cylindrical receiving surface  311  for a bearing sleeve  41 , on which is mounted a bearing  42  of bearing stand  4 . The outside diameter of receiving surface  311  is slightly smaller than the outside diameter of clamping bushing  31  which receives hub part  33 . 
     When hub part  33  is to be exchanged, bearing stand  4  is first pulled off so that the left end of changing device  3  is exposed. By turning threaded bushing  35  counterclockwise, threaded bushing  35  executes a motion to the left and, due to the forces transmitted further by axial bearing  36 , clamping bushing  31  is driven to the left as well. Hub part  33  is released and can be pulled off to the left via changing device  3 . 
     When hub part  33  is clamped, threaded bushing  35  is turned to the right, whereby clamping bushing  31  is also displaced to the right, hub part  33  is pushed in a defined way against a stop  320  of shaft end  32 , and thus hub part  33  is radially clamped. 
     Thus, with the arrangement according to FIG. 4, the radial forces are transferred directly towards the left onto bearing sleeve  41  and bearing stand  4  by clamping bushing  31  clamped between hub part  33  and conical shaft end  32 . It does not matter whether threaded bolt  34  is screwed into shaft end  32  or if inside thread  351  is arranged directly on the extended shaft end since bolt  34  and shaft end  32  do not have to absorb transverse forces. 
     This embodiment with clamping bushing  31  extended towards the left could be carried out also by using hydraulic operations. An embodiment in which a hydraulically operated changing device is used with a double-sided bearing is shown in FIG.  5 . FIG. 5 shows this embodiment with a hydraulic operation; however, the embodiment could also be designed as being mechanically operated. In the embodiment according to FIG. 5, the radial forces emanating from hub part  20  are guided into shaft  11  via clamping bushing  30  and are transferred via the left shaft end and clamping sleeve  50  to bearing sleeve  41  and bearing stand  4 . In this embodiment, shaft end  40  is not a screwed-in bolt, but rather is directly part of shaft  11  as a screwed-in bolt would not bring about the necessary radial stiffness or the necessary exactness. 
     Referring to FIG. 5, the right-hand side shows a conical section  10  of a shaft  11  surrounded by a hub part  20 . Hub part  20  rests against a step  100  of shaft  11  and may be, for example a profile-shaping straightening roll or comparable tool, which has to be changed as quickly as possible at low expenditure. Changing device  1  according to the invention permits a quick and simple dismantling of hub part  20 , on the one hand, and provides a safe and precise support of hub part  20  on shaft  11 . As shown, changing device  1  consists substantially of a clamping bushing  30 , a shaft end  40 , and a clamping sleeve  50 . The clamping sleeve  50  has a cylindrical receiving surface  511  for a bearing sleeve  41 , on which is mounted a bearing  42  of bearing stand  4 . The outside diameter of receiving surface  511  is slightly smaller than the outside diameter of clamping bushing  30  which receives hub part  20 . 
     The parts shown in FIG. 5 are substantially rotation-symmetric. FIG. 5 shows that within the zone of step  403  extending circumferentially, the shaft end  40  has a groove  4030  extending all around, the groove being open toward the end of shaft end  40 . On the bottom of circular groove  4030 , provision is made for a sealing ring  60   b.  A pressure ring  70   b  is placed on top of sealing ring  60   b.  Circular step  403  is joined by a second shaft step  405 , whose outside diameter is distinctly smaller than circular step  403 . 
     FIG. 5 shows that clamping bushing  30  basically has the shape of a can having its bottom and lid missing. Across about ⅔ of its length, starting from the right end, clamping bushing  30  has a conically tapering inside zone  304  corresponding with conical shaft section  10 . Conical inside zone  304  is followed by an internal circumferential groove  3050  and a cylindrical inside zone  305  having a width or bore only slightly larger than the one of circular step  403  of shaft end  40 . Following the cylindrical inside zone  305 , provision is made for a step  303  extending all around. 
     FIG. 5 shows that starting from its right-hand end, clamping bushing  30  has a substantially cylindrical outer contour. FIGS. 5 and 2, furthermore, show that clamping bushing  30  has longitudinal slots  301  uniformly distributed over its circumference. Clamping bushing  30  is circumferentially divided by the longitudinal slots  301  into clamping wing sections  308 , which can be radially expanded outwardly, which, as explained herein below, is required for flawless radial clamping effect of clamping bushing  30 . The longitudinal slots  301  can be cast in elastic sealing compound in order to prevent the penetration of dust or the like. In order to explain the mode of operation of changing device  1  of the invention, the following description describes how the parts are mounted for easier understanding. 
     When the changing device is assembled, clamping bushing or collet  30  is pushed over shaft end  40  from the left side. After clamping bushing  30  has been completely pushed over shaft end  40 , clamping sleeve  50  is then screwed to shaft end  40  until it rests against the end face of shaft end  40 . 
     The radial width of clamping sleeve  50  conforms to approximately the width of step  303  of the clamping bushing  30  extending circumferentially so that clamping sleeve  50  has sufficient space for circular groove  503 , with the opening thereof being directed toward the inside step  303  of clamping bushing  30 . As in circular groove  4030 , there is provided both a sealing ring  60   a  and pressure ring  70   a  in circular groove  503 . 
     In FIG. 5, after clamping sleeve  50  has been installed as described above, changing device  1  forms a clamping system which is closed within itself and rigidly connected with shaft end  40 . The axial path of displacement of the clamping bushing  30  is limited by clamping sleeve  50  and step  403  of shaft end  40 . 
     FIG. 5 shows changing device  1  in the “unclamped” operating condition. However, the outboard bearing stand  4  with the bearing  42  and the bearing sleeve  41  has already been connected to the clamping sleeve  50  by means of screws  507 . 
     In order to connect hub part  20  to the shaft  11 , threaded pin  408  has to be moved to the left as far as possible in order to allow piston  401  to move. Then, by turning the threaded pin  508 , piston  501  in clamping sleeve  50  is actuated and generates oil pressure in the circular groove  503  through a hydraulic duct  5010 . Pressure build-up is effected on sealing ring  60   a  and thus also on pressure ring  70   a  downstream, whereby pressure ring  70   a  is pressed against the left side  3030   a  of inside step  303  of clamping bushing  30 , attempting to push the latter as far as possible in the direction of conical shaft section  10 . Through longitudinal slots  301  of clamping bushing  30 , it is now possible for clamping wings  308  to spread radially outwardly in the direction of shaft end  10  in proportion to the axial path of displacement, which results in a clamping effect between clamping bushing  30  and hub part  20 , on the one hand, and shaft section  10  on the other hand. This clamping effect is substantial, so that changing device  1  is suitable for transmitting high torque, as well as radial and axial forces between the shaft and the hub even without interconnecting a fitted spring. 
     To ensure safe clamping, a small gap has to be provided between right side  3030   b  of step  303  and circular step  403  of shaft end  40 , when the changing device is in the clamped condition. It has to be noted here that hub part  20 , which prior to clamping is loosely pushed onto clamping bushing  30 , is forced, in a defined way, against step  100  of shaft  11  by the movement of clamping bushing  30  to the right. This represents an important adjustment advantage. 
     When the changing device is to be changed from operating,mode “clamped” to operating mode “released”, the procedure is as follows: 
     After removing the screws  507  which connect the bearing sleeve  41  to the clamping sleeve  50 , the bearing stand  4  with the bearing  42  and the bearing sleeve  41  can be removed. Threaded pin  508  is moved to the left as far as possible in order to allow piston  501  to move. Oil is supplied via the hydraulic piston  401  of shaft end  40  and received by sealing ring  60   b  via a hydraulic duct  4010 . Similar to the way the “clamping” mode worked in groove  503 , oil pressure now builds up in circular groove  4030 , and acts on pressure ring  70   b  via sealing ring  60   b.  Pressure ring  70   b  is thereby pressed in the axial direction to the left, out of groove  4030 , and thereby acts directly on the right side  3030   b  of inside step  303 , causing the latter to be displaced to the left. Together with the displacement of inside step  303 , the entire clamping bushing  30  is simultaneously forced axially to the left as well. Due to their elasticity, clamping wings  308  again move radially inward, returning to their starting positions, which finally cancels the clamping effect between the participating components (shaft section  10 , clamping bushing  30 , hub part  20 ). FIG. 5 shows that the maximum axial displacement path of clamping bushing  30  is limited in this connection by the right side of clamping sleeve  50 , the latter representing a stop for the left side  3030   a  of inside step  303 . Since the inside diameter  3031  (FIG. 2) of inside step  303  is slightly larger than the outside diameter of the second shaft step  405  of clamping pin  40 , the axial displacement of clamping bushing  30  is not obstructed. 
     Hub part  20  can thus be pulled without any problem from clamping bushing  30  to the left, and thus from shaft end  10  and replaced by another hub part. It has to be noted that a suitable fit is maintained between the outside diameter of clamping bushing  30  and the inside diameter of hub part  20 , which, when changing device  1  is in the released condition, permits an easy axial displacement of hub part  20  on clamping bushing  30 . 
     Changing devices  1 ,  2 ,  3  for shaft and hub connections described above can be preferably used for rolling mills, straightening machines, tube-welding installations and profiling plants. However, other application cases are, of course, conceivable. 
     While several embodiments of the present invention have been shown and described, it will be obvious that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.