Patent Publication Number: US-7584698-B2

Title: Embossing assembly for sheet material

Description:
RELATED APPLICATION 
   Applicants claim priority of Italian Patent Application No. MI 2004A 002038, filed Oct. 26, 2004. 
   BACKGROUND 
   The present invention refers to an embossing assembly for sheet material, in particular paper, such as tissue paper, toilet paper and the like. 
   Embossing machines provided with embossing rollers or cylinders supported rotatably at their ends, by means of bearings, in the side panels of the embossing machine frame are known on the market. Such embossing rollers are provided with a sleeve, generally of steel, engraved with the embossing patterns, so as to be able to perform embossing of respective plies of paper which are subsequently coupled together by nested or tip-to-tip coupling, so as to obtain a multi-ply embossed web. 
   Embossing rollers must be accessible and/or removable both for maintenance (for example, replacement of bearings) and due to the need to change the embossing patterns on the web and thus the engraving on the sleeve of the embossing roller. Removal of the embossing rollers leads to considerable machine stoppages, because it is necessary to remove and re-assemble some parts of the embossing machine due to the difficult accessibility to these embossing rollers. Furthermore, the embossing rollers must be set to make the engravings of the two plies coincide. For this purpose it is necessary to perform a relative transverse and angular adjustment of the rollers. This operation proves to be complex, slow and laborious. For these reasons, machine stoppages for replacement of the embossing rollers are of the order eight hours. 
   Furthermore, depending upon the diameter and engravings of each embossing roller, it is necessary to vary the center distance between the two embossing rollers. In embossing machines of the prior art, the center distance between the embossing rollers is generally fixed since the embossing roller supports are integral with the side panels of the frame in a fixed position, or the housing of the bearing is even formed in the side panels themselves. 
   There are other embossing machines in which an embossing roller is mounted on a movable side panel which is pivoted to a fixed side panel. In these machines adjustment of the center distance between the embossing rollers is achieved by adjusting the rotation and thus the proximity of the movable side panel to the fixed side panel. This solution makes production of the machine costly and adjustment of the center distance complex. 
   European patent application EP 0 928 682 discloses an embossing machine in which an embossing roller is supported rotatably at its ends by two movable portions of the side panel, pivoted to the two fixed side panels of the machine frame. In this manner, to carry out replacement of the embossing rollers, the two movable portions of the side panel are rotated so as to move the two embossing rollers apart and leave space for removal thereof. 
   Even if this system speeds up embossing roller changes compared to embossing machines in which the rollers are mounted in fixed side panels, there still remain therein some drawbacks in that the access space is in any case limited, it is not possible to carry out simultaneous replacement of both rollers, and adjustment of the distance between the rollers is complex. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is to overcome the drawbacks of the prior art by providing an embossing assembly for sheet material that is able to simplify and speed up embossing roller replacement and adjustment operations. 
   Another object of the present invention is to provide such an embossing assembly that is reliable and at the same time suitable to be installed in a compact embossing machine that occupies little space. 
   These objects are achieved in accordance with the invention with the characteristics listed in the appended independent claims. Additional advantageous embodiments of the invention are described in the dependent claims. 
   The embossing assembly for sheet material according to the invention comprises at least two embossing rollers, the ends of which are mounted rotatably in the side panels of an embossing machine. Each of the side panels is divided into a portion of a fixed side panel and at least one portion of a movable side panel. 
   The ends of the embossing rollers are mounted in supports which are fixed removably in seats formed in the fixed side panels or in the movable side panels of the machine. In this manner, when the movable side panel is moved with respect to the fixed side panel, a space is cleared for removal of at least one portion of the support of the embossing rollers. 
   It is obvious that this system allows easy replacement of the embossing rollers, which can be raised and lowered by means of a hoist, after disengagement from the side panel of the portions of the support or of the support. 
   The movable portion of side panel advantageously translates with respect to the fixed portion of the side panel, and the supports of the embossing rollers are mounted removably in the fixed side panel. According to an alternative embodiment, the movable portion of side panel is pivoted to the fixed portion of the side panel. 

   
     DESCRIPTION OF THE DRAWING 
     Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non-limiting embodiment thereof, illustrated in the appended drawings, in which: 
       FIG. 1  is a perspective view of an embossing machine according to the invention in which the gluing assembly has been removed; 
       FIG. 2  is a diagrammatic view in cross section of the embossing machine of  FIG. 1 , taken along a vertical plane between the two side panels of the machine and parallel thereto, in which the gluing assembly has also been schematised; 
       FIG. 3  is a fragmentary perspective view illustrating one of the fixed shoulders of the machine which supports the embossing assembly according to the invention, and a movable shoulder part in the open position for changing the embossing rollers; 
       FIG. 4  is a fragmentary perspective view, illustrating the other fixed shoulder of the machine which supports the embossing rollers, showing one of the other rollers about to be removed and the part of movable shoulder omitted for greater clarity; 
       FIG. 5  is a partially exploded perspective view illustrating two embossing rollers supported at their ends by the bottom part of the supports according to the invention, the upper parts of the supports being illustrated in a raised position; 
       FIG. 6  is a perspective view of the assembled supports for the ends of the embossing rollers; 
       FIG. 7  is a fragmentary longitudinal sectional view of an embossing roller supported at its ends by fixed supports on the fixed side panels of the machine; 
       FIG. 7A  is an enlarged view of the detail enclosed in the circle A of  FIG. 7 ; 
       FIGS. 8 through 13  are six diagrammatic side elevational views illustrating the various stages for removal of the embossing cylinders; 
       FIG. 14  is a side elevational view showing a device for simultaneous removal of both embossing cylinders; 
       FIG. 15  illustrates another embodiment of the invention in which a portion of the side panel is rotatably or tiltingly mounted with respect to a fixed portion of the side panel; 
       FIG. 16 , illustrates the rotatable portion of the side panel of  FIG. 15  in a closed position; 
       FIG. 17  illustrates a locking device for the movable portion of the side panel; and 
       FIGS. 18 and 19  are enlarged fragmentary views of the locking device of  FIG. 17 . 
   

   DESCRIPTION OF SPECIFIC EMBODIMENT 
   An embossing assembly according to a preferred embodiment of the invention is described with the aid of the figures. 
     FIG. 1  shows an embossing machine, denoted as a whole with reference numeral  1 . The embossing machine  1  comprises two side panels or shoulders, each of which comprises at least one fixed portion  2 ,  2 ′ disposed fixedly on a base  3 . Two rollers or embossing cylinders  4 A,  4 B are mounted rotatably in the fixed portions  2 ,  2 ′ of the side panels. Each embossing roller  4 A,  4 B comprises a sleeve of engraved steel  5 A,  5 B and two end portions  6 A,  6 B with a smaller diameter. The ends  6 A,  6 B of the embossing rollers are supported rotatably on supports  7  mounted in the fixed portions  2 ,  2 ′ of the side panels. 
   The operation of the embossing machine  1  is described schematically with reference to  FIG. 2 . The embossing machine  1  works two plies W 1 , W 2  of material, for example, paper, and carries out embossing of each of the two plies between a pair of rollers coupled together, comprising an engraved steel roller and a rubber-coated counter-pressure roller. The upper ply W 1  passes through the top pair of rollers consisting of a first embossing roller  4 A and a rubber-coated roller  8 A. The two rollers  4 A,  8 A are brought into contact with a working pressure. The upper ply W 1  passes through the two rollers  4 A,  8 A so as to be marked with the engraving of the steel roller  4 A. 
   On leaving the point of contact between the two rollers  4 A,  8 A, the upper ply W 1  remains in contact with the steel roller  4 A for an angle of about 270°. In this manner the upper ply W 1  can come into contact with a glue distributing assembly  9  which, by means of a distributing roller  10 , deposits a layer of glue on the ply W 1 . It should be noted that the distributing roller  10  and the upper embossing roller  4 A are not in contact, but are adjusted so that the glue comes into contact only with the paper ply W 1 . 
   The glue distributing assembly  9  works as follows. The glue is contained in a tank  11 . A first roller  12  rotates partially immersed in the tank  11  and distributes the glue which is deposited on the its surface on the glue distributing roller  10 . The glue distributing roller  10 , thanks to its particular surface finish, collects a uniform amount of glue on its surface and spreads a uniform layer of glue on the paper ply W 1 . 
   The bottom ply of paper W 2  passes between the bottom pair of rollers consisting of the second embossing roller  4 B and a rubber-coated roller  8 B so as to be marked by the engraving of the steel roller  4 B. The ply W 2  remains wound on the steel roller  4 B for an angle greater than 90°. The bottom ply W 2  then detaches from the steel roller  4 B to couple with the upper ply W 1 . In this coupling the surface of the bottom ply W 2  comes into contact with the glued surface of the upper ply W 1 . 
   The two embossing rollers  4 A and  4 B are near to, but not in contact with, each other. A gap  14  just large enough for the two plies W 1 , W 2  to pass without touching each other is left therebetween. Moreover, the embossing rollers  4 A and  4 B must be placed at a definite center distance to facilitate the timing system of the rollers, that is, to ensure that the engravings of the two plies W 1 , W 2  are superimposed one upon another during coupling, in the case of nested coupling. 
   Above the bottom embossing roller  4 B there is disposed a coupling roller  13 , commonly known as a marrying roller, mounted on arms which are pivoted to the side panels of the machine. In this manner, the marrying roller  13  enters into contact with the upper embossing roller  4 A and presses the two plies W 1 , W 2  together so as to cause gluing to take place and to obtain a two-ply embossed web W as the output. The two-ply embossed web W is guided out of the embossing machine  1  by means of idler rollers  15  suitably disposed to adjust the pull thereof. 
   It should be noted that this embossing machine  1  proves to be very compact, and, without the invention, access to the steel rollers  4 A and  4 B would be problematical because the rollers are obstructed by the gluing assembly  9  and by the upper rubber-coated roller  8 A on one side and by the marrying roller and the lower rubber-coated roller  8 B on the other side. Furthermore, for the operating reasons described above, the embossing rollers  4 A and  4 B must be disposed near to each other and at a well-defined center distance to regulate their timing and the width of the gap  14  for passage of the plies W 1  and W 2 . 
   The embossing assembly according to the invention is described hereunder. 
   With reference to  FIGS. 1 ,  3  and  4 , two oblique, upwardly open seats, designed to receive the supports  7  of the ends  6 A,  6 B of the embossing rollers, are formed in the fixed portions  2 ,  2 ′ of the side panels of the machine. Alongside the seat of each support  7  is disposed a bracket  20  integral with the fixed portion of the side panel  2 ,  2 ′. A guide rail  21  ( FIG. 3 ) disposed along a horizontal plane is formed on the upper edge of the bracket  20 . A movable portion  23  of the side panel is disposed in a vertical plane coinciding with the plane of the fixed portion  2 ,  2 ′ of the side panel, and is mounted on slides  22  so that the movable portion  23  can slide on the guide rail  21 . 
   The bottom edge of the movable portion  23  of the side panel ( FIG. 3 ) has a profile  24  which repeats the profile of the upper part of the support  7 . In this manner, the movable portion  23  of the side panel, translating on the guide rail  21 , can move from a closed position (illustrated in  FIGS. 1  and  2 ) in which the profile  24  of the bottom edge of the movable portion of the side panel is situated above the support  7  for the ends of the embossing rollers, to an open position (illustrated in  FIG. 3 ) in which an open space is left above the support  7  for the ends of the embossing cylinders. 
   As shown in  FIG. 2 , the marrying roller  13  and the various idler rollers  15  are mounted in the movable portion  23  of the side panel. Thus, translation of the movable portion of the side panel  23  into the open position opens a space above the embossing rollers  4 A and  4 B to allow easy replacement thereof, for example, by raising and lowering by means of an overhead crane or hoist. Clearly, during operation of the embossing machine  1 , the movable portion of side panel  23  must be closed to bring the marrying roller  13  and the idler rollers  15  into the correct working position. 
   The two movable side panels  23  disposed on the fixed portions  2 ,  2 ′ of the side panels can be moved manually or in an automated fashion by means of actuators or a motorized system. Clearly, movement of the two movable portions of the side panel is synchronized. Locking systems are provided to lock the movable portions  23  of the side panels in the open and closed positions. The slides  22  of the movable portions  23  of the side panels are connected to the guide rails  21  of the bracket  20  by means of precise locators (for example, pins), so as to ensure that the relative positions of the marrying roller  13  with respect to the first embossing roller  4 A are respected. 
   In the above description and in the figures a single movable portion of the side panel has been illustrated on each fixed portion of the side panel. However, each side panel can be provided with a plurality of movable portions of the side panel slidable on the fixed portions of the side panel or a plurality of movable portions mutually slidable with respect to each other. 
   The support  7  for the ends of the embossing rollers is described in detail with reference to  FIGS. 5 ,  6 ,  7  and  7 A. As shown in  FIG. 6 , the support  7  is shaped substantially as an overturned “8”, so as to define two annular seats  40  within which bushes  32  ( FIG. 5 ) mounted at the ends  6 A,  6 B of the embossing cylinders  4 A,  4 B are housed. As shown in  FIG. 7A , roller or ball bearings  38  are housed inside the bushes  32 . 
   With reference mainly to  FIG. 6 , the support  7  comprises a bottom portion  30  and a top portion  31  that can be assembled with each other. Each of the bottom and top portions  30 ,  31  of the support  7  is shaped as an overturned “3”, so as to define a concave arched seat with an arc of 180°. The top support  31  can be in a single piece or divided into two separate parts  31 A and  31 B, each consisting of a substantially C-shaped arc of 180°. 
   The bottom part  30  of the support has a flat protruding bar  33  provided with holes  34  to receive bolts for fixing to the fixed portion  2 ,  2 ′ of the side panel of the machine along the oblique edge of the seat designed to receive the support  7 . Through holes  34  are also provided in the bottom part  30  of the support to receive bolts for fixing to the fixed portion of the side panel. 
   The top part  31  of the support has feet  35  in which through holes  36  are formed to receive bolts for fixing to the bottom part  30  of the support. 
   Annular grooves  41  are formed in the annular seats  40  of the support  7  for receiving an annular protrusion  39  formed in the bearing bushes  32  for correct centering of the bushes  32  in the seats  40  of the support. Furthermore, as shown in  FIG. 7A , thrust pins  50 , disposed with their axes parallel to the axis of the embossing cylinder  4 A, are provided in the bushes  32  to allow axial adjustment of the bushes  32 . 
   The use of this support  7  for the bearing bushes  32  which can be mounted integrally with the fixed portion  2 ,  2 ′ of the side panel, but is distinct and removable thereform, allows various advantages. In fact, it is also possible to disconnect the entire support  7  from the fixed portion  2 ,  2 ′ of the side panel and to remove the embossing rollers  4 A,  4 B together with the support  7 . In this manner the embossing rollers can be replaced with another pair of rollers already assembled with another support. 
   By changing the size of the support  7  and in particular the center distance between the two housings  40  for the bushes  32  at the ends of the embossing rollers, it is possible to achieve complete flexibility in the choice of the embossing rollers (diameter and working distance between the sleeves of the two embossing rollers). In fact, the two embossing rollers  4 A,  4 B must work at a distance from each other that is well defined but variable according to the engraving present in the roller sleeve. 
   Furthermore, by varying the diameter of the rollers, their peripheral speed is adapted to the ideal embossing speed (in relation to the engraving or the product being processed), without changing the transmission system when the pair of embossing rollers is changed. 
   The support system  7  together with the bearing bush  32  mounted on the end of the embossing roller allows easy mounting of the roller to be performed. In the first assembly, the grooved guide  41  formed in the seat  40  of the support  7  facilitates centering of the bush  32  during housing, in that the protrusion  39  of the bush engages in the grooved guide  41 . Furthermore, by means of the thrust pins  50  for axial adjustment, it is possible to adjust the position of the bush  32  and cause the embossing roller to translate axially to perform transverse timing of the rollers, and to lock the bearing  38  inside the bush  32 . 
   Once the previous adjustment has been performed, in subsequent operations of replacement and assembly of the embossing roller, transverse timing will be maintained and it will only be necessary to fix the top part  31  of the support after having lowered the roller with an overhead crane so that the bushes  32  of the roller engage in the seats  40  of the bottom part  30  of the support. 
   Although in the figures the support  7  has been illustrated mounted in the fixed portion of side panel and a movable portion  23  of the side panel translating with respect to the fixed portion  2 ,  2 ′ of the side panel has been provided, it will be understood that the support  7  according to the invention can also be mounted removably either in a movable portion of the side panel or in a fixed portion of the side panel of the machine, irrespective of whether the movable portion of the side panel of the machine translates or rotates with respect to the fixed portion of the side panel. 
   In fact, in any case, movement of the movable portion of the side panel with respect to the fixed portion of the side panel will create the space necessary for removal of the entire support  7  or of portions  31 ,  31 A,  31 B of the support to perform replacement of the rollers. Thus, provision of the removable support considerably facilitates the operation of replacement of the embossing rollers compared to the prior art. 
   Furthermore, even though in the figures the support  7  has been illustrated with a single bottom portion  31  provided with two seats  40  to receive the two ends of two embossing rollers, the support  7  can clearly be divided into two separate supports, each to receive the end of a mandrel. In this case each support will have a bottom part with a single seat  40  to receive the end of the mandrel. 
   The method of replacement of the embossing assembly according to the invention is described with the aid of  FIGS. 8-14 . 
     FIG. 8  illustrates an embossing machine  1  in operation, in which the bushes on the ends of the embossing rollers  4 A,  4 B are engaged in the supports  7  which are closed (i.e., the bottom part  30  and the top part  31  of the supports  7  are assembled together). The supports  7  are fixed to the fixed portions  2 ,  2 ′ of the side panels of the machine. The movable portions  23  of the side panels are in the closed position with their bottom edges above the top parts  31  of the supports  7 . 
   When embossing rollers must be replaced, the motor system of the machine is stopped and, as shown in  FIG. 9 , the movable portions  23  of the side panels are translated on the guides  21  of the fixed portions  2 ,  2 ′ of the side panels to bring them into the open position, so as to leave an empty space above the embossing rollers  4 A,  4 B and the supports  7 . 
   At this point, as shown in  FIG. 10 , the bolts that fixed the top part  31 A of the support  7  are unscrewed and the top part  31 A of each support  7  is removed. 
   Subsequently, as shown in  FIG. 11 , the first embossing roller  4 A is gripped with a hoist or overhead crane equipped with a suitable gripper  55  and raised so as to remove the bushes  32  on the ends of the embossing roller from the housings  40  of the bottom parts  30  of the respective supports. 
   After having removed the first embossing roller, the second top portion  31 B of each support  7  is removed as shown in  FIG. 12 , and the second embossing roller  4 B is also removed by means of a hoist as shown  FIG. 13 . 
   As shown in  FIG. 14 , the hoist for lifting the embossing rollers can have a particular gripper means  56  able to simultaneously lift both rollers  4 A,  4 B. 
   At this point the two housings  40  of each bottom support  30  are free to receive the new embossing rollers. Clearly, in an inverse manner with respect to the previous description, the supports  7  are closed, fixing the top parts  31 A,  31 B on the bushes of the new embossing rollers, and the movable portions  23  of the side panels are closed to start a new machine cycle. 
   If it is desired to change the center distance between the embossing rollers  4 A,  4 B, the two supports  7  are removed from the side panels together with the embossing rollers  4 A,  4 B, disengaging the bottom support  30  from each fixed portion  2 ,  2 ′ of the side panels. A new support  7  is then mounted on each fixed portion of the side panels with a different center distance between the seats from the previous one. 
     FIGS. 15 and 16  illustrate a modified embodiment which is similar to the previous embodiment except that movable portions  123  of the side panels are rotatably or tiltingly mounted with respect to the fixed portions  2 ,  2 ′ of the side panel. The movable portions are mounted for a rotation on a journal or axle  60  which is mounted on the fixed portions  2 ,  2 ′ of the side panels. 
     FIG. 15  illustrates the movable portions of the side panels in an open position.  FIG. 16  illustrates the movable portions of the side panels in a closed position. 
     FIGS. 17-19  illustrate a locking device  62  which can be used to lock the movable portions of the side panels. The locking device can be used with any type of movable side panels. 
   Referring to  FIGS. 18 and 19 , the locking device includes a latch  63  which is rotatably mounted on each of the movable portions  23  or  123  of the side panels and which is engagable with a pin  64  on the fixed portions  2 ,  2 ′ of the side panels. The latch  63  is movable between latched ( FIG. 18 ) and unlatched ( FIG. 19 ) positions by an actuator  65 . In the embodiment illustrated the actuator is a piston  66  and a cylinder  67 . Extension of the piston rotates a lever  68  counterclockwise which rotates the latch clockwise. 
   Numerous changes and modifications of detail which are within the reach of a person skilled in the art can be made to the present embodiment of the invention without thereby departing from the scope of the invention as set forth in the appended claims.