Abstract:
In replacing a sleeve on a printing machine drum, the diameter of the drum is reduced by moving the drum parts toward one another to facilitate removing the sleeve, and/or mounting another sleeve onto the drum, and increasing the drum diameter by moving the drum parts away from one another.

Description:
FIELD OF THE INVENTION 
     The invention pertains to a sleeve on a drum and a process for changing a sleeve on a drum. 
     BACKGROUND OF THE INVENTION 
     In the printing industry a number of rollers and drums are used for various purposes. Drums in printing machines are often equipped with sleeves that have various layers, and depending upon the use of the drum, fulfill different functions. For example, imaging cylinders in a photoelectric printing machine are equipped with photoelectric sleeves, that are capable of accepting a latent electrostatic image to which toner particles adhere, whereby a printed image is created that is transferred to a printing medium when the imaging cylinder is rolled over the printing medium. The sleeves on the drums are replaced from time to time, whereby the drum as the element that supports the sleeve, continues to be used, and is not replaced. 
     Prior art provides, for example, a compressed air mechanism for replacing the sleeve, which makes compressed air available from inside the drum. The diameter of the sleeve is enlarged by the compressed air, the strength of the bonding between the sleeve and the drum is diminished, and the sleeve that is ordinarily tightly held against the drum, can be slid off. A disadvantage of this prior art solution is the fact that a compressed air apparatus, along with a compressor for providing compressed air at several bars, must be available. 
     With the prior art process, not all kinds of sleeves can be securely attached to a drum. At a certain thickness and with certain characteristics of the material, the process for replacing the sleeve from the drum by compressed air fails to work. For example, sleeves made of thick metal cannot be slid onto a drum. The result is that metal sleeves with a smaller wall thickness are manufactured in order to assure that they can be mounted on a drum, whereby the manufacturing process becomes more complicated and expensive. 
     SUMMARY OF THE INVENTION 
     One object of the invention is to make it possible to easily replace sleeves on drums. An additional object of the invention is to mount, even thick-walled sleeves made of hard material onto a drum. 
     The invention achieves these objects by providing for replacing a sleeve on a drum in a printing machine, whereby the diameter of the drum is decreased, in that the drum parts are moved closer to one another, the sleeve is removed, another sleeve is slid onto the drum. The diameter of the drum is increased, by moving the drum parts away from one another. In addition, a sleeve-supporting drum for a printing machine is made available, where the drum has two drum halves that can be moved toward one another, in order to change the diameter of the drum. 
     The drum parts are beneficially placed under compression by at least one clamping bolt together with a compression spring for the purpose of moving the parts toward one another, and they are moved against the compression by an eccentric mechanism for the purpose of moving them apart from one another. In this way a simple structure is achieved. 
     As a particular benefit, the drum parts are placed under compression by at least one clamping bolt together with a compression spring, and to move the drum parts away from one another they are relieved of the compression via a second conical ring around a shaft of the drum that engages with a first slotted conical ring between the drum parts, and moves the drum parts away from one another. 
     In another embodiment of the invention, a shaft of the drum has a conical shape for engaging on the drum parts, for the purpose of moving the drum parts toward one another and apart from one another. In another special embodiment the drum is a processing apparatus for manufacturing and processing sleeves of every kind. In this instance the drum serves as a temporary mounting for the sleeves during the manufacturing process and processing. Because changing out the sleeves happens very often for these functions, the drum is particularly well suited for this purpose. 
     The drum is used in a particularly beneficial manner, as an imaging cylinder in an electro-photographic printing machine. Using the drum as an imaging cylinder also fulfills the increased demand for imaging cylinders with respect to precision fitting of the sleeve on the drum, where great precision is required for transfer of the image. In addition, because such drums are often replaced, the drum is capable of serving as a coated drum in a printing machine, for example, as a fuser roller, a pressure roller, or an intermediate roller. 
     The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiment presented below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which: 
         FIG. 1  shows schematically, a sectional side elevation of a drum with two clamping bolts, two compression springs, and a lever along with an eccentric mechanism for applying and releasing compression from sleeves of every kind; 
         FIG. 2  shows schematically, a longitudinal section of the drum, whereby the clamping bolt springs are relieved of compression, and the diameter of the drum around the eccentric path is reduced; 
         FIG. 3  shows schematically, a longitudinal section of the drum, similar to the view shown in  FIG. 2 , whereby the clamping bolt springs are under compression, and the diameter of the drum is increased to a standard compressioned size, whereby the sleeve fits tightly on the drum; 
         FIG. 4   a  shows schematically, a side view of the drum similar to the view shown in  FIG. 1 , without the lever, however, whereby the eccentricity of a second bearing is illustrated, the clamping bolt springs are under compression, and the sleeve fits tightly on the drum; 
         FIG. 4   b  shows schematically, a longitudinal section of the drum similar to the view shown in  FIG. 3 , whereby the drum is under compression as in  FIG. 4   a;    
         FIG. 5  shows a perspective view of the drum, with the two drum parts of an alternative embodiment of the invention; 
         FIG. 6  shows a cross section through the drum, with the two drum parts as in  FIG. 5 ; 
         FIG. 7  shows a longitudinal section through the drum, with the two drum parts as in  FIG. 5 , with a second slotted ring on the shaft with conically shaped outer surfaces and first ring near the drum parts with corresponding inner surfaces; 
         FIG. 8  shows a perspective cutaway view of a drum, similar to the ones in  FIGS. 5 through 7 ; 
         FIG. 9  shows a perspective cutaway view of a drum like the one in  FIGS. 5 through 8 , in which an L-shaped recess for guiding the pin can be seen; 
         FIG. 10  shows a perspective view of an alternative embodiment of the invention; 
         FIG. 11  shows a cross section of the embodiment shown in  FIG. 10  with (1) a shaft nut and corresponding threads in a third slotted ring with cone-shaped slotted outer surfaces, whereby the third slotted ring can be pushed forward and backward on a shaft; and (2) the third slotted ring with corresponding cone-shaped inner surfaces; 
         FIG. 12  shows a cross section of the drum shown in  FIGS. 10 and 11 ; 
         FIG. 13  shows a perspective cutaway view of the drum shown in  FIGS. 10 through 12 ; and 
         FIG. 14  shows another perspective view of the drum shown in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the accompanying drawings,  FIG. 1  shows schematically, a side view of an exemplary drum  2 , for example, for use as an imaging cylinder in an electro-photographic printing machine. The drum  2  can also be used, for example, to hold a sleeve that is being processed, i.e., the drum  2  is in such case an apparatus used for manufacturing and processing sleeves  1 , and serves as a temporary mount. The drum  2  incorporates an eccentric mechanism  18  that is described below and is shown in  FIG. 1  as an extruded profile. Other constructions of the drum  2  are feasible. The drum  2  has an inner bearing seat  20  and an outer bearing seat  21  that has a larger diameter than the inner bearing seat  20 . The inner bearing seat  20  and the outer bearing seat  21  are joined together by ribs  22  that extend from the inner bearing seat  20  to the outer bearing seat  21 , connect the two bearing seats, and are preferably manufactured as a unit from the same material as the bearing seats. Between the inner bearing seat  20 , the outer bearing seat  21 , and the ribs  22 , are recesses which in this side view, have a near-trapezoidal shape. 
     The drum  2  includes a first drum part  4  and a second drum part  5 . Each of the two drum parts  4  and  5  constitutes half of the drum  2 , each having a flat side and a curved side, and when joined together on their flat sides they form a complete drum  2  between which is a crack  23 , as shown in  FIG. 1 . When the two drum parts  4  and  5  are pushed together, the inner bearing seat  20  and the outer bearing seat  21  become closed rings, and a narrow crack  23  forms between the two drum parts  4  and  5 . Inside the drum  2 , a shaft  17  is mounted that rotates the drum  2  during operation. 
     The two drum parts  4  and  5  are tightly connected together along the crack  23  via two clamping bolts  6  that pass on both sides through holes located between the inner bearing seat  20  and the outer bearing seat  21 . In  FIG. 1 , one clamping bolt  6  is placed on each of the two sides of the inner bearing seat  20 , while two additional clamping bolts  6  are placed at corresponding locations at the other longitudinal end of the drum  2 , however, the latter two bolts are not visible in  FIG. 1 . The two drums parts  4  and  5  are precisely and firmly attached to each other so that neither of the drum parts  4  and  5  overlap the other drum part  4  or  5 , axially or vertically relative to the axis of the drum, i.e., the two drum parts  4  and  5  must be in suitable coincidence, one with the other. This is achieved mainly by the sleeve  1 , which guides the two drum parts  4  and  5  tightly together. This results in the drum being formed into a geometrically precise cylinder shape. 
     Two clamping bolts  6  can be seen, one on each side of the drum  2 . The clamping bolts  6  extend through holes in the ribs  22  of the first drum part  4 , and through holes in the ribs  22  of the second drum part  5 , whereby the holes of the first drum part  4  and the second drum part  5  align, and the clamping bolts  6  extend from a recess  3  in the first drum part  4  to a recess  3  in the second drum part  5 . 
     Encircling each of the clamping bolts  6  are two compression springs  7 , whereby each clamping bolt  6  has a compression spring  7  in the first drum part  4 , and a compression spring  7  in the second drum part  5 . The ends of the compression springs  7  make contact respectively with the bolt head  8  of the clamping bolt  6  and the rib  22  of each drum part  4  and  5 , and the springs are compressed between the two. The compression springs  7  exert a force in the direction shown by the arrow, which ascertains, that the first drum part  4  and the second drum part  5  are pressed securely against one another. In this way, a force exerted between the drum parts  4  and  5  presses the drum parts  4  and  5  against one another. 
     In addition, a lever  10  is mounted on the drum  2 , which encircles the shaft  17  at one end of the drum  2 , so that pushing on the lever  10  results in rotation of the shaft  17 . The lever  10  is used here as an example, and serves to secure the shaft  17  so that it cannot turn, relative to the bearings  12  and  14  of the drum parts  4  and  5 . Other mechanisms for securing the shaft  17 , so as to prevent turning are feasible. For this purpose, the lever  10  has two lever arms  100  that embrace the shaft  17 , whereby a pin  25  connects both lever arms that secure the shaft  17  to one another and assures that the lever arms  100  embrace the shaft  17  securely and tightly, so that the lever  10  is clamped to the shaft  17 . Securing the lever  10  to the shaft  17  with the lever arms  100  assures that a movement of the lever  10  is converted to a rotation of the shaft  17 . 
     When the shaft  17  is rotated by the lever  10 , the diameter of the drum  2  is changed as described below. The drum parts  4  and  5  are moved toward one another, in the direction of the arrow, by rotation of the lever  10  and the resulting exertion of force. The drum parts  4  and  5  are pressed against one another by the compression springs  7 . This is the condition in which the sleeve  1  is slid onto the drum  2 , namely, the condition of the drum  2  with the compression relieved. After the sleeve  1  has been slid onto the drum  2  the lever  10  is moved against the direction of the curved arrow and back into its initial position as shown in  FIG. 1 . This results in the diameter of the drum  2  increasing to its standard diameter. This is the diameter that is suited for operation of the ideally, cylindrically shaped drum  2 . The drum parts  4  and  5  move apart from one another.  FIG. 1  shows a sleeve  1  that has been slid onto the drum  2 ; such a sleeve usually consists of a thin-walled pipe. After the sleeve  1  has been slid onto the drum  2  and the diameter of the drum has been enlarged, the drum  2  is ready for operation. In its operationally ready condition, the drum  2  has an optimally round cylindrical shape; as opposed to the situation that exists when the drum is not under compression, namely, the drum  2  is not out of round. 
       FIG. 2  shows a side section through an embodiment of the drum  2  of the invention. Shown is a first eccentric disk  11  on the shaft  17 , through the center of which the shaft  17  extends. Encircling the first eccentric disk  11  is a first bearing  12 , which has the same width as the first eccentric disk  11  and which on its outer side, extends into a first recess  15  on the inner side of the first drum part  4  and the second drum part  5 . The first recess  15  is formed evenly on the inner side of the first drum  4  and the second drum  5  and has a depth a 1  on the inner side of the first drum part  4  and the second drum part  5 . The depth a 1  of the first recess  15  amounts, for example, to 0.3 mm. The circumferential surface of the first bearing  12  lies on the inner surface of the first drum part  4  and the second drum part  5 , in the first recess  15 . The drum parts  4  and  5  are supported on the first bearing  12 . 
     In addition, a second eccentric disk  13  is provided next to the first eccentric disk  11 , which corresponds in size approximately to the first eccentric disk  11 , and through which the shaft  17  extends, not through the center, but eccentrically. One of the side surfaces of the second eccentric disk  13  lies against a side surface of the first eccentric disk  11 . The drum  2  is not to be operated in the compression free condition shown in  FIG. 2 . This condition is used only for replacing the sleeve  1 . The drum  2 , with the sleeve  1 , does not have an optimally cylindrical form when in this condition. The first eccentric disk  11  and the second eccentric disk  13  are shifted radially a certain distance apart from one another. The axes of the first eccentric disk  11  and the second eccentric disk  13  are not in alignment with one another, as can be seen in  FIG. 2 . 
     The distance between the upper surface of the shaft  17  and the circumferential surface of the second eccentric disk  13  on one side of the shaft  17 , is shown by b 1 , while the distance between the shaft  17  and circumferential disk  13  on the opposite side of the shaft  17 , is shown by b 2 , whereby b 1  is not equal to b 2 . In this case b 1  is greater than b 2 . This means that the second eccentric disk  13  on the shaft  17  is out of round or balance, relative to the shaft  17 , because the shaft  17  does not extend through the center of the second eccentric disk  13 . The second eccentric disk  13  has, as does the first eccentric disk  11 , a second bearing  14  that embraces the second eccentric disk  13 , whereby the outer side of the second bearing  14  extends into the first recess  15  in the first drum part  5 , while its outer side extends into a second recess  16  in the second drum part  5 . 
     The second recess  16  on the inner side of the second drum part  5  is deeper than is the first recess  15  on the inner side of the first drum part  4  and the second drum part  5 . The depth of the second recess  16 , relative to the first recess  15  on the inner side of the second drum part  5 , is shown by a 2 . Thus, two steps are formed on the inner side of the second drum part  5 , a first step from the inner side of the second drum part  5  to the first recess  15 , and a second step from the first recess  15  to the second recess  16 . On the inner side of the first drum part  4 , a step is formed from the inner side of the first drum part  4  to the first recess  15 , but there is no second step. Viewed from the inner side of the second drum part  5 , the second recess  16  is deeper in the second drum part  5  than the first recess  15 . The first recess  15  passes over from the first drum part  4  to the second drum part  5 , without an offset or a step, while the second recess  16  in the second drum part  5  forms an offset, or a step, with the first recess  15  in the first drum part  4 . In this condition, the shaft  17  is rotated such that the second bearing  14  around the second eccentric disk  13  extends into the second recess  16 , and exerts no pressure on the inner side of the second drum part  5 , so that the free second drum part  5  presses against the first drum  4 . 
     The circumferential surface of the second bearing  14  in the area of the inner side of the second drum part  5 , shown in  FIG. 2  above, does not butt against the recess  16 , and it is also at a certain distance from the inner surface in the area of the inner side of the first drum part  4 , shown in the lower part of FIG.  2 . Therefore, the second bearing  14  is not in contact with the drum parts  4  and  5 . The distance of the drum parts  4  and  5  from one another is defined and determined by the diameter of the first bearing  12 . The subject condition is referred to as the compression-free condition, because the sleeve is no longer held in place by drum parts  4  and  5 , and the sleeve is easily replaceable because of the play between it and the drum  2 . In the condition depicted in  FIG. 2 , the drum parts  4  and  5  lie close to one another, and the diameter of the drum  2  is minimal. The two drum parts  4  and  5  are closer to one another in  FIG. 2  than in  FIG. 3 . Thus, a manual replacement of the sleeve  1  is also possible. The shape of the drum  2  continues to be adjustable and changeable by the compression springs. 
       FIG. 3  shows a side view that is similar to the one in  FIG. 2 , but the condition here is the under-compression condition. The shaft  17  has been rotated by reversing the lever position, for example, by 180°, compared to the position of the shaft  17  in  FIG. 2 . As can be seen, the second eccentric disk  13  is now in a different position, relative to the first eccentric disk  11 , than was the case in  FIG. 2 . The second eccentric disk  13  and the second bearing  14  that is attached to it have been rotated along with the shaft  17 . The larger distance b 1  from the shaft  17  to the outer side of the second bearing  14  is now, after reversal, of the position of the lever  10 , located on the lower side of the second eccentric disk  13 . The smaller distance b 2  is located on the opposite side, i.e., on the upper side of the second eccentric disk  13 . Consequently, the second bearing  14 , which encircles the second eccentric disk  13 , has been moved out of the second recess  16  of the drum part  5 . 
     In the under-compression condition the second bearing  14  projects out into the first recess  15  of the second drum part  5  and the first drum part  4 . The circumferential surface of the second bearing  14  is now located in the area of the inner side of the second drum part  5 , shown in the upper area of  FIG. 3 , in the first recess  15  at a certain distance from the second recess  16 , while in the area of the inner side of the first drum  4 , shown in the lower area of  FIG. 3 , in the first recess  15  it abuts against the inner surface of the first drum part  4 . One half of the second bearing  14  that is located in the first drum part  4  borders on the inner surface of the first drum part  4 , while the other half of the bearing  14  that is located in the second drum part  5  does not border on the inner surface of the second drum part  5 . In other words, the drum part  5  rests on the first bearing  12  and drum part  4  rests the second bearing  14 . The drum parts  4  and  5  have, relative to their positions in the compression-free condition as shown in  FIG. 2 , been moved farther apart from one another. 
     The positioning of the eccentric second eccentric disk  13  has been selected so that the standard target dimension of the drum  2  is achieved. The first bearing  12  surrounding the first eccentric disk  11 , which is not out of round relative to the shaft  17 , is located in both conditions, i.e., the under-compression condition and the compression-free condition, at the same level in the first recess  15 . Because the drum parts  4  and  5  are farther apart from one another in the operational or under-compression condition, the first bearing  12  borders only the inner surface of the second drum  5 ; and in the first drum part  4  there is a certain distance between the first bearing  12  and the inner surface of the first drum part  4 . The under-compression condition that is shown here, is characterized by the fact that the first bearing  12  abuts tightly against the second drum part  5 , and the second bearing  14  abuts tightly against the first drum part  4 , whereby the drum parts  4  and  5  are moved during operation, by a friction fit with bearings  12  and  14 . In the under-compression condition as shown in  FIG. 3 , the operational condition, the diameter of the drum  2  is, relative to the condition as shown in  FIG. 2 , increased to its standard size, i.e., the operational condition for printing or for processing the sleeve  1  is achieved because the sleeve  1  is securely held on the drum  2 . Both of the drum parts  4  and  5  are located farther apart from one another in  FIG. 3  than in  FIG. 2 . In this condition it is not possible to replace the sleeve. 
       FIG. 4   a  schematically shows a side view of a drum  2  in an embodiment of the invention that is similar to that shown in  FIG. 1 . Shown here is a section through the second eccentric disk  13  and the second bearing  14 . A dashed line shows the center line of the drum  2 . It can be seen, that the center line of the drum  2  does not coincide with the below-lying center line  30  of the second eccentric disk  13  and the second bearing  14 . The center line  30  of the second eccentric disk  13  runs through the second eccentric disk  13 , which is at a distance a 3  from the center line of the drum  2 . This distance a 3 , is the eccentric throw of the drum  2 . The shaft  17 , not shown in  FIG. 4   a , has been rotated by the lever  10  into the position shown in  FIG. 3 . When the lever  10  is in this position, the drum  2  is in its under-compression condition, in which the diameter of the drum  2  is set at its standard size, and the sleeve  1  is securely held in place and is ready for operation. For operation of the printing machine the drum  2  is in the condition shown in  FIG. 4   a.    
       FIG. 4   b , schematically shows a longitudinal section of an embodiment of the drum  2  in the same under-compression condition as is shown in  FIG. 3  and  FIG. 4   a . The center line of the shaft  17 , shown by a dashed line, runs through the center of the first eccentric disk  11 , but not through the center of the second eccentric disk  13 . The center line  30 , running through the second eccentric disk  13 , is at a distance a 3  from the center line of the first eccentric disk  11 , and from the center line of the drum  2 , the eccentric throw. The circumferential surface of the first bearing  12 , surrounding the first eccentric disk  11  abuts against the inner surface of the first drum part  5 , and is at a certain distance from the inner surface of the second drum part  4 . The circumferential surface of the second bearing  14 , surrounding the second eccentric disk  13 , abuts against the inner surface of the first drum part  4 , and is at a certain distance from the inner surface of the second drum part  5 . 
       FIG. 5  shows a perspective view of an embodiment of the invention, which has a shaft  17 , that passes through two solid drum halves  4  and  5 , similar to what is shown in the previous example. A pin  110  runs through the shaft  17 ; its purpose is to slide a conical second slotted ring  27  along the shaft  17 . The structure and function of this embodiment will be described below, with the aid of the drawings that follow.  FIG. 6  shows a bottom view of the view shown in  FIG. 5 .  FIG. 7  shows a longitudinal view through the drum parts  4  and  5 , and the shaft  17  from  FIGS. 5 and 6 , whereby the structure of the embodiment is graphically shown. The second, multi-slotted ring  27 , which is cone shaped, surrounds a section of the shaft  17 . The outer surface of this second slotted ring  27  tapers in the direction of drum parts  4  and  5 . On the inner side of the drum parts  4  and  5  is a first slotted ring  26 , on which the outer surface of the cone shaped, second slotted ring  27  slides along the shaft  17 . When the pin  110 , along with the second slotted ring  27 , is pushed in the direction of the arrow, between the drum parts  4  and  5  and the outer surfaces of the second slotted ring  27  on the shaft slide along the inner surfaces of the first slotted ring  26 , the drum parts  4  and  5  are pressed apart. The drum parts  4  and  5  move away from one another, and the diameter of the drum  2  is increased. 
     A spring  70  located in a recess  170 , which is in the shaft  17 , encircles the shaft  17 , and begins at the tapered end of the cone shaped, second slotted ring  27 , and ends at a first detent  36 . The spring  70 , on the shaft  17 , is compressed when the pin  110  is pushed in, whereby the spring  70 , together with the second slotted ring, is pushed in the direction of the drum parts  4  and  5 , until the ring reaches a final position, at which the diameter of the drum  2  is increased, and the drum  2  with the sleeve in place is ready for operation. For replacement of the sleeve  1 , the diameter of the drum  2  is reduced in that the second slotted ring  27  is moved away from the drum parts  4  and  5 , whereby the spring expands and relaxes, and the drum parts  4  and  5  move toward one another. The spring  70  exerts an outward force against the direction of the arrow, and contributes greatly to the fact that the second slotted ring  27  is moved away from the drum parts  4  and  5 . The result is that replacing the sleeve  1  becomes a great deal easier. 
       FIG. 8  shows a perspective cutaway view of the embodiment of the invention, shown in  FIGS. 5 through 7 . In this view, the drum parts  4  and  5  are of solid construction. Visible here, in particular, is the first slotted ring  26  that is located between the drum parts  4  and  5  and the shaft  17 . The first slotted ring  26  contains a number of neighboring fingers  250 , which are both separated from each other and formed by the slots  260 . The second slotted ring  27  has a similar construction, so that the conical surfaces of the first slotted ring  26  and the second slotted ring  27  come together, one with the other. The end of the first slotted ring  26 , which is located between the drum parts  4  and  5  and faces inward relative to the drum  2 , abuts against a second detent  40 , that is formed from a shoulder on the inner side of the drum parts  4  and  5 . The first slotted ring  26  is solid and flexible, so that pressure applied to it from the outer side of the first slotted ring  26  reduces the diameter of the first slotted ring  26 . This change in diameter is assured by the fact that the first ring  26  is especially constructed to have slots  260 . 
     If the second slotted ring  27  is pushed toward the drum parts  4  and  5  in the direction of the arrow by a force applied to the pin  110 , a force from the inner side of the drum parts  4  and  5  acts upon the slotted ring  26 , so that the fingers  250  move away from one another, and the slots  260  become wider. By the cone-shaped second slotted ring  27  on the shaft  17 , whose diameter increases toward the outside relative to the drum parts  4  and  5 , against the direction of the arrows, the force that is acting on the slotted ring  26  from the inside is increased when the pin  110  is pushed in. The pin  110  makes contact with the first slotted ring  26  and the force applied to the pin  110  is transmitted to the first slotted ring  26 . The outer part of the second slotted cone-shaped ring  27  that has a larger diameter is pushed between the drum parts  4  and  5 . While this is occurring, an increasing force from the first slotted ring  26  to the inner sides of the drum parts  4  and  5  develops, which causes the diameter of the drum  2  to increase. 
     When pulling on the pin  110  causes the pin  110  to be pulled out of the drum parts  4  and  5 , the fingers  250  of the first slotted ring  26  move toward one another, the slots  260  become narrower, the force on the inner side of the drum parts  4  and  5  abates, and the diameter of the drum  2  decreases in size. Now, one part of the second slotted cone-shaped ring  27  that has a smaller diameter than the other part with the larger diameter, the tapered part, is still located between the drums  4  and  5 , the other part of the slotted cone-shaped ring  27  that has a larger diameter, is located outside the drum  2 , separated from the two drum parts  4  and  5 . In this case, the diameter of the drum  2  is decreased. 
       FIG. 9  shows a perspective cutaway view of the embodiment, as shown in  FIGS. 5 through 8 . Here, an L-shaped recess  111 , for guiding the pin  110 , has been formed in the shaft  17 . It extends from one side of the shaft  17  to the other, as can be seen in  FIG. 7 . The pin  110  fits vertically into the L-shaped recess  111  from one side of the shaft  17 , and comes out on the other side of the shaft  17 . The L-shaped recess  111  has a longer, longitudinal recess that runs parallel to the axis of the shaft  17 , and an equally wide, shorter, longitudinal recess that runs perpendicular to the axis of the shaft  17  and connects with the other recess. The pin  110  is inserted into the L-shaped recess in the larger section parallel to the axis of the shaft  17  for pushing the first slotted ring  27  in and out, and the pin locks in position in the smaller section perpendicular to the axis of the shaft  17  when the first slotted ring  27  is pushed the proper distance into the drum  2 , and the drum parts  4  and  5  are apart from one another, i.e., the diameter of the drum  2  is increased as described above. When the pin  110  becomes locked in place in the smaller longitudinal recess perpendicular to the axis of the shaft  17  of the L-shaped recess  111 , the positions of the pin  110  and the first slotted ring  27  that abuts against the pin  110  are securely fixed, as is the diameter of the drum  2 . The drum  2  is then ready for use. 
       FIG. 10  shows a perspective view of another embodiment of the invention. Here, the change in diameter of drum  2  is accomplished by an arrangement that is described in the following drawings.  FIG. 11  shows a cross section through the two drum parts  4  and  5  and through the shaft  17 . Attached to the shaft  17  is a threaded shaft nut  29 . A third slotted ring  33 , which encircles the shaft  17 , and can be moved along it, engages with the shaft nut  29 , whereby the third slotted ring  33  is connected to the shaft nut  29 . The third slotted ring  33  has a conical surface, whereby the third conical ring  33  becomes narrower in the direction of drum  2 . The side of the third slotted ring  33  that lies against the shaft nut  29 , has a greater diameter than the side of the third slotted ring  33  that lies against the drum parts  4  and  5 . The first slotted ring  26 , along which the outer surfaces of the third slotted ring  33  slide when the shaft  17  is moved, is located on the inner sides of the drum parts  4  and  5 . When the shaft nut  29  is turned, it moves in the direction of the arrow, and the third slotted ring  33  also moves because it is connected to the shaft nut  29 . The third slotted ring  33  moves in the direction of the arrow, along the shaft  17 , until the shaft nut  29  reaches the first detent  36 , which runs around the shaft  17  and forms a shoulder on it. The shaft  17 , thus, has an offset at the first detent  36  at which the diameter of the shaft  17  increases in the direction of the drum  2 . Because of the conical shape of the third slotted ring  33  when it is inserted, the diameter of the first slotted ring  26 , increases and the drum parts  4  and  5  that are lying against the first slotted ring  26 , are pressed apart. Turning the shaft nut  29  causes the drum parts  4  and  5  to separate from one another and the diameter of the drum  2  to increase. 
       FIG. 12  shows a bottom view of the drum  2  as it is shown in  FIG. 10 , along with the shaft nut  29  and the drum parts  4  and  5 .  FIG. 13  shows a perspective cutaway view of the above embodiment with the first slotted ring  26 , and the second slotted ring  27 , which encircle the shaft  17 . Finally,  FIG. 14  shows another cutaway perspective view, similar to that shown in  FIG. 13 . The operation is in each case as described in detail above. 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
     PARTS LIST 
     
         
           1  sleeve 
           2  drum 
           3  recesses 
           4  first drum part 
           5  second drum part 
           6  clamping bolts 
           7  compression spring 
           8  bolt heads 
           9  lever 
           11  first eccentric disk 
           12  first bearing 
           13  second eccentric disk 
           14  second bearing 
           15  first recess 
           16  second recess 
           17  shaft 
           18  eccentric mechanism 
           20  inner bearing seat 
           21  outer bearing seat 
           22  ribs 
           23  crack 
           25  pin 
           26  first slotted, conical ring 
           27  second slotted, conical ring 
           29  shaft nut 
           30  center line 
           31  threads 
           33  third slotted ring 
           36  first detent 
           40  second detent 
           70  spring 
           100  lever arm 
           110  pin 
           111  L-shaped recess 
           170  recess 
           250  finger 
           260  slot