Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2014/000545, filed Mar. 4, 2014, which claims priority of European Application No. 13001151.3, filed Mar. 7, 2013, the contents of which are incorporated by reference herein. The PCT International Application was published in the French language. 
     
    
       [0002]    The present invention concerns a method for adjusting the radial gap existing between two tools for converting a flat substrate. The invention relates to a converting arrangement for a flat substrate, the arrangement provided with two cylindrical converting tools, in a machine for producing packaging. The invention also relates to a converting cassette for a flat substrate, comprising a converting arrangement for the flat substrate. The invention concerns a converting unit for a flat substrate, provided with a converting cassette for the flat substrate. The invention concerns a converting unit for a flat substrate, comprising at least one converting arrangement for the flat substrate. The invention also concerns a machine for producing packaging from a flat substrate, comprising at least one converting unit for the flat substrate. 
       TECHNICAL BACKGROUND 
       [0003]    A machine for producing packaging is intended for the manufacture of boxes which form the packaging, after folding and gluing of the boxes. In the machine, an initial flat substrate, such as a continuous web of cardboard, is unwound and is printed by a printing machine, which is made up of printer groups. The web is then transferred into a converting unit, in order to make plate elements, in this case boxes. 
         [0004]    The converting unit comprises at least one converting arrangement provided with two cylindrical rotary tools, which are positioned parallel to one another so as to cooperate. The web circulates between the two tools in order to be converted there. The two tools turn in respective opposite directions. The first tool is rotatably mounted in first and second spaced apart bearings and the second tool is rotatably mounted in third and fourth spaced apart bearings. Tightening elements maintain firmly together and prestress the first and the third bearings and also the second and the fourth bearings. Most of time, the converting arrangement forms a cassette. The cassette is inserted by sliding it into each of the lateral supporting frames of the unit. 
         [0005]    The cassette allows the tools to be changed quickly, in terms of the conversions of the substrate to be carried out. The packaging manufacturer has at least two cassettes. A first cassette is in the machine currently operating and is configured and adapted in terms of the current converting job. During this time, a second cassette is in the process of being assembled and adjusted so as to be adapted and configured in terms of the following converting job. When the job is changed, the operator takes out the old cassette and inserts the new cassette, reducing the time the machine is stopped to a minimum. 
         [0006]    For example, one of the arrangements or one of the cassettes is a rotary cutting arrangement or a rotary cutting cassette respectively. A first cylindrical cutting tool is provided with knifes, and a second cylindrical tool is smooth and is called an anvil. A radial gap between the first cylindrical cutting tool and the second cylindrical tool has to be adjusted in a very precise manner. 
         [0007]    At the moment of the cut, the edges of the knives of the cutting tool must pass as close as possible to the anvil cylinder so as to carry out a clean cut. The edges of the knives, however, must not touch the anvil cylinder as they would be irretrievably destroyed during rotation. The constituent material of the substrate, i.e. the fibers in the case of cardboard, must not appear at the cut. Neither is it desirable to have dust originating from the cut in the constituent material of the substrate. The point of adjusting the radial gap is also to compensate for the progressive wear on the knifes of the cutting tool. This is why the optimum radial gap between the two cylindrical rotary tools is adjusted to the micron. 
       Prior art 
       [0008]    Document EP-0&#39;764&#39;505 describes a cutting station where each end of the two cylindrical rotary tools comprises a conical lateral rolling ring. The two rings of the first tool roll along the two rings, which are associated and diametrically opposed, of the second tool respectively. Each of the rings has a truncated form, with an inclined surface which comes into contact with the inclined surface of the directly associated ring. The position of the rings of the first tool is able to be modified laterally. The lateral displacement of a ring with respect to its associated ring brings about a variation in the overall thickness of the two rings together. This varies the space between the first and the second tools, so that the radial gap is obtained in a precise manner. 
         [0009]    To do this, the operator initially loosens the elements for tightening the bearings. Then he displaces the assembly formed by the first bearing, the second bearing and the first tool so as to move it away from the assembly formed by the third bearing, the fourth bearing and the second tool respectively. This displacement is provided by pivoting adjusting wedges mounted on micrometer screws. 
         [0010]    However, the solution takes a long time. Each of the wedges has to be turned manually and in a sequential manner, which takes time. Another disadvantage is that it is difficult to displace the first and the second bearings in a simultaneous manner and over the same distance. Often, the first bearing is lifted being skewed with respect to the second bearing. 
       SUMMARY OF THE INVENTION 
       [0011]    A main objective of the present invention is to implement a method of adjustment for an arrangement intended to convert a flat substrate. A second objective consists in providing a method allowing an adjustment of the radial gap existing between two converting tools for a flat substrate to be facilitated. A third objective is to perfect a converting arrangement for a flat substrate, intended for a converting unit in a machine producing packaging. A fourth objective is to realize a converting arrangement with rotary tools allowing simplified adjustment to be obtained and the time taken to adjust the radial gap between the two tools to be reduced. A fifth objective is to resolve the technical problems mentioned for the arrangements of the prior art. A sixth objective consists in providing a cassette comprising a converting arrangement for the converting unit. Yet another objective is succeeding in inserting a converting unit into a machine for producing packaging. 
         [0012]    A method is used to adjust a radial gap existing between two tools for converting a flat substrate, in a converting arrangement for the flat substrate. The converting arrangement for the flat substrate comprises a first cylindrical rotary converting tool and a second cylindrical rotary converting tool. Each of the first and the second cylindrical rotary converting tools is provided with two conical lateral rolling rings respectively. The first cylindrical and the second cylindrical rotary converting tools are arranged together and cooperate to convert the substrate. The converting arrangement for the flat substrate comprises a first lateral bearing and a second lateral bearing which hold the first cylindrical rotary converting tool for rotation. The converting arrangement for the flat substrate also comprises a third lateral bearing and a fourth lateral bearing which hold the second cylindrical rotary converting tool for rotation. The converting arrangement for the flat substrate comprises elements for tightening the first lateral bearing to the third lateral bearing and elements for tightening the second lateral bearing to the fourth lateral bearing. 
         [0013]    In accordance with one aspect of the present invention, the method comprises the steps of:
       loosening the elements for tightening the first lateral bearing to the third lateral bearing,   loosening the elements for tightening the second lateral bearing to the fourth lateral bearing   pushing the first lateral bearing away from the third lateral bearing, along a predetermined distance, and leaning on the third lateral bearing,   pushing the second lateral bearing away from the fourth lateral bearing, along a predetermined distance, and leaning on the fourth lateral bearing,   modifying a lateral position of at least one of the conical lateral rolling rings on at least one of the cylindrical rotary converting tools,   moving the first lateral bearing closer to the third lateral bearing,   moving the second lateral bearing closer to the fourth lateral bearing,   retightening the elements for tightening the first lateral bearing to the third lateral bearing, and   retightening the elements for tightening the second lateral bearing to the fourth lateral bearing.       
 
         [0023]    In other words, in one stage, the first bearing is pushed to move it away from the third bearing, and the second bearing is pushed to move it away from the fourth bearing. The stages that consisting in pushing and moving the corresponding bearings away or closer are each effected simultaneously and in one single action. With such stages for pushing away in one stage, adjustment are simpler, which thus allows operator errors to be avoided. As a result, adjustment time is reduced. 
         [0024]    The flat substrate is defined, for example, as a material in a continuous web, such as paper, flat cardboard, corrugated cardboard, glued corrugated cardboard, flexible plastic, for example polyethylene (PE), polyethylene-terephthalate (PET), bioriented polypropylene (BOPP) or yet other materials. 
         [0025]    A converting arrangement for a flat substrate comprises a first cylindrical rotary converting tool and a second cylindrical rotary converting tool. Those tools are arranged together and cooperate together to provide conversion of the flat substrate. The converting arrangement for the flat substrate comprises a first lateral bearing and a second lateral bearing which respectively hold the first cylindrical rotary converting tool for rotation. The converting arrangement for the flat substrate also comprises a third lateral bearing and a fourth lateral bearing which hold the second cylindrical rotary converting tool for rotation. 
         [0026]    In another aspect of the invention, the converting arrangement for the flat substrate comprises translation means to move apart in a radial direction over a predetermined distance, and conversely in order to move closer, the first lateral bearing from/to the third lateral bearing, and the second lateral bearing from/to the fourth lateral bearing, between two positions, a first position moved closer in which the two cylindrical rotary converting tools cooperate, and a second position moved apart in which the two cylindrical rotary converting tools are capable of being modified, so as to adjust a radial gap between the first cylindrical rotary converting tool and the second cylindrical rotary converting tool. 
         [0027]    Expressed another way, the translation means are of an on-off type. An operator moves the translation means between the off and on positions. With the translation means in the on position, the first lateral bearing and the third lateral bearing are moved apart from the second lateral bearing and from the fourth lateral bearing, respectively. The two tools are therefore also moved apart from one another, which allows an operator to intervene in order to modify the tools easily and to adjust them as a result. When the translation means are in the off position, the tools are once again in the operating state. 
         [0028]    In another aspect of the invention, a converting cassette for a flat substrate comprises a converting arrangement for the flat substrate which has one or several of the technical characteristics described above. The converting cassette makes access, assembly and disassembly of the tools easier for the operator carrying out the adjustments and maintenance of the unit and of the machine. 
         [0029]    According to another aspect of the invention, a converting unit for a flat substrate is provided with at least one converting cassette for the flat substrate. The cassette is provided with a converting arrangement for the flat substrate, having one or several of the technical characteristics described above. 
         [0030]    According to another aspect of the invention, a converting unit for a flat substrate comprises at least one converting arrangement for the flat substrate, having one or several of the technical characteristics described above and claimed. 
         [0031]    According to another aspect of the invention, a machine for producing packaging from a flat substrate comprises at least one converting unit for the flat substrate, having one or several of the technical characteristics described above and claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    The invention will be well understood and its diverse advantages and different characteristics will be highlighted better from the following description and from the non-limiting exemplary embodiment, with reference to the accompanying schematic drawings, in which: 
           [0033]      FIG. 1  shows a schematic side view of a converting unit; 
           [0034]      FIG. 2  shows an isometric view of a cassette provided with a converting arrangement according to the invention; 
           [0035]      FIG. 3  shows a partial longitudinal sectional view of two front bearings of the cassette in  FIG. 2 ; 
           [0036]      FIGS. 4 and 5  show an enlarged longitudinal sectional view of the translation means with a first position moved closer and a second position moved apart respectively; 
           [0037]      FIG. 6  shows a partial isometric view of the actuating means for the translation means. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0038]    A machine for producing packaging (not shown) processes a material or a flat substrate. In this case, it is a substrate in the form of a continuous web, for example of flat cardboard. As shown in  FIG. 1 , the machine comprises a converting unit for a substrate  1  in order to convert the web  2 . The direction of feed or of unwinding (Arrow F in  FIG. 1 ) of the web  2  and of the converted web following the longitudinal direction indicates the upstream direction and the downstream direction of the unit  1 . The positions front and rear are defined with regard to the cross direction, as being the driver or operator side and the side opposite the driver or operator side respectively. 
         [0039]    The machine can have a web unwinder, units such as printing units, means for controlling the quality and the register of the print, a web guiding means and yet other units which are positioned upstream of the unit  1 . 
         [0040]    The converting unit  1  is a unit for embossing, creasing and cutting. The web  2  arrives in the unit  1  through the upstream transverse side thereof, at a constant speed. An infeed group comprising drive rollers and return rollers for the web  2  is provided at the input to the unit  1 . The unit  1  converts the web  2 , gradually by embossing it, creasing it and cutting it. 
         [0041]    The unit  1  delivers repeats or converted boxes  3 , being as a result in embossed, creased and cut flat cardboard. The boxes  3  leave the unit  1  through the downstream transverse side thereof, at the same constant speed. 
         [0042]    The boxes  3 , prepared in the unit  1 , are then separated laterally and longitudinally from one another in a separating station then are received in a receiving station (not shown). 
         [0043]    The unit  1  first comprises a first arrangement for providing the embossing  4 , arranged upstream, i.e. at the input to the unit  1 . The embossing arrangement  4  is provided with the top rotary embossing tool  6 , positioned parallel to a bottom rotary embossing tool  7 . In the exemplary embodiment, an embossing cassette  8  comprises the embossing arrangement  4 . 
         [0044]    The unit  1  comprises a second arrangement for providing the creasing  9 , disposed downstream of the embossing arrangement  4 . The creasing arrangement  9  is provided with a top rotary creasing tool  11 , positioned parallel to a bottom rotary creasing tool  12 . In the exemplary embodiment, a creasing cassette  13  comprises the creasing arrangement  9 . 
         [0045]    The unit  1  comprises a third arrangement providing the cutting  14 , disposed downstream of the creasing arrangement  9 , i.e. at the output of the unit  1 . The cutting arrangement  14  is provided with a first top rotary cutting tool  16 , positioned parallel to a second bottom rotary cutting tool  17 . In the exemplary embodiment, a cutting cassette  18  comprises the cutting arrangement  14 . 
         [0046]    The arrangements  4 ,  9  and  14 , and thus the cassettes  8 ,  13  and  18 , are placed following one another so that each one realizes its respective conversion, by embossing, creasing and cutting the web  2 . A waste stripping tool in the form of a cylinder provided with stripping needles can also be provided in place of the bottom rotary cutting tool  17 . Other combinations are possible such as a top cylinder forming both a cutting tool and a creasing tool. 
         [0047]    The rotational axis of each of the tools for embossing  6  and  7 , creasing  11  and  12  and cutting  16  and  17  is oriented transversely with respect to the unwinding direction F of the web  2 . The rotational direction (Arrow Rs in  FIG. 2 ) of the top tools for embossing  6 , creasing  11  and cutting  16  is reversed with respect to the rotational direction (Arrow Ri in  FIG. 2 ) of the bottom tools for embossing  7 , creasing  12  and cutting  17 . 
         [0048]    The cassettes for embossing  8 , creasing  13  and cutting  18  are capable of being introduced into a supporting structure  19  of the unit  1 , of being fixed to the supporting structure  19 , of producing, then conversely, are capable of loosened from the positive connection with the supporting structure  19  and of being extracted from the supporting structure  19 . The unit  1  thus comprises three transverse housings provided in the supporting structure  19  for each of the three cassettes  8 ,  13  and  18 . The cassettes  8 ,  13  and  18  are introduced vertically, from above, with respect to the supporting structure  19  into the transverse housings. Conversely, the cassettes  8 ,  13  and  18  can be removed vertically with respect to the supporting structure  19 , out of their respective transverse housings. 
         [0049]    The cutting arrangement  14 , and therefore the cutting cassette  18 , comprises (see  FIG. 2 ) the first top cylindrical rotary tool  16  which is provided with cutter threads (not shown) machined or built on its circumference in terms of the configuration of the boxes to be realized. The second bottom cylindrical rotary tool or anvil  17  has a smooth circumference. The web  2  unwinds F in the radial gap  20  between the top tool  16  and the anvil  17 . The top tool  16  is arranged so as to cooperate with the anvil  17  in order to convert, i.e. cut the web  2 . 
         [0050]    The top tool  16  is provided at its front end with a first front top rolling ring  21 . The top tool  16  is provided at its rear end with a second rear top rolling ring  22 . The anvil  17  is provided at it front end with a third front bottom rolling ring  23 . The anvil  17  is provided at its rear end with a fourth rear bottom rolling ring  24 . 
         [0051]    All the rings  21 ,  22 ,  23  and  24  have a truncated form. The top rings  21  and  22  thus have an inside curved surface laid flat against the curved surface of the top tool  16 . The bottom rings  23  and  24  have an inside curved surface laid flat against the curved surface of the anvil  17 . The top rings  21  and  22  of the top tool  16  contact, bear on and roll on the opposite bottom rolling rings  23  and  24 , respectively of the anvil  17 . This results in the front top ring  21  having an outside conical surface which abuts against an outside conical surface of the front bottom ring  23  and the rear top ring  22  having an outside conical surface which abuts against an outside conical surface of the rear bottom ring  24 . 
         [0052]    In the exemplary embodiment, the two top rings  21  and  22  of the top tool  16  are laterally displaceable (Arrow L in  FIG. 2 ). When the operator displaces laterally L a ring  21  and  22  with respect to its opposite ring  23  and  24 , for example by a few tenths of a millimeter, their respective conical surfaces are not positioned in the same place. The overall accumulated thickness of the front ring  21  of the top tool  16  and of the front ring  23  of the anvil  17 , or of the rear ring  22  of the top tool  16  and of the rear ring  24  of the anvil  17  vary compared to one another. This results in a variation in the radial space, i.e. in the radial gap  20 , between the top tool  16  and the anvil  17 . 
         [0053]    The cutting arrangement  14 , and therefore the cutting cassette  18 , comprises a first top front bearing  26  and a second top rear bearing  27 , which hold the first tool, i.e. the top tool  16 , by its rotational axis  28  for rotation. The cutting arrangement  14 , and therefore the cutting cassette  18 , comprises a third bottom front bearing  29  and a fourth bottom rear bearing  31  which hold the second tool, i.e. the anvil  17 , by it rotational axis  32  for rotation. The base of the two bottom bearings  29  and  31  rests on the supporting structure  19  when the cutting cassette  18  is inserted into the unit  1 . 
         [0054]    The cutting arrangement  14 , and therefore the cutting cassette  18 , comprises driving means, in the form of a gear wheel arrangement (not shown in the Figures), intended to rotate the two tools  16  and  17 . When the cassette  18  is inserted into the supporting structure  19 , the gear wheel arrangement meshes with the teeth of a gear wheel combined with an electric motor for rotational movement. 
         [0055]    The first top front bearing  26  of the top tool  16  is fixed to the third bottom front bearing  29  of the anvil  17 , and the second top rear bearing  27  of the top tool  16  is fixed to the fourth bottom rear bearing  31  of the anvil  17 , so as to constitute the cutting cassette  18 . To hold the cassette  18  all in one unit, tightening elements, in the form of four ties, front upstream and front downstream  33 , and rear upstream and rear downstream  36 , in a vertical manner cross the top front bearing  26  and the top rear bearing  27 , on both sides of the rotational axis  28  of the top tool  16 . The bottom end of each of the four ties, front  33  and rear  36 , is threaded and is screwed into a female thread of the bottom front bearing  29  and of the bottom rear bearing  31  respectively. Four nuts, front upstream and front downstream  34 , and rear upstream and rear downstream  37 , are screwed onto the top end of the four ties, front  33  and rear  36 , respectively. The nuts  34  and  37  block the ties  33  and  36  by bearing on a top face of the top front bearing  26  and of the top rear bearing  27  respectively and allowing the bearings to be prestressed in twos. 
         [0056]    The cutting cassette  18 , as well as the embossing cassette  8  and the creasing cassette  13 , comprise two gripping lugs  38  each provided on the top face of the top front bearing  26  and of the top rear bearing  27 . The two lugs  38  are intended for cooperating with the lifting means in order to raise the cassette  18 ,  8  and  13  vertically and transport it outside of the supporting structure  19 . 
         [0057]    So as to be able to carry out an adjustment of the radial gap  20  between the top tool  16  and the anvil  17 , just one top ring or more often the two top rings  21  and  22  have to be displaced along their tool  16 . To do this, the top tool  16  is moved vertically away from the anvil  17 , and the rings  21 ,  22 ,  23  and  24  are thus freed from any constraint of support. 
         [0058]    According to the invention, the cutting arrangement  14 , and therefore the cutting cassette  18 , comprises first translation means  39  in order to move the first bearing  26  vertically away (Arrow U in  FIGS. 3 and 4 ) from the third bearing  29 , and conversely in order to move the first bearing  26  vertically closer (Arrow D in  FIGS. 3 and 5 ) to the third bearing  29 . The cutting arrangement  14 , and therefore the cutting cassette  18 , comprises second translation means in order to move the second bearing  27  vertically away from the fourth bearing  31 , and conversely in order to move the second bearing  27  vertically closer to the fourth bearing  31 . The first and second means of translation  39  move the first bearing  26  and the second bearing  27  respectively along a predetermined distance. 
         [0059]    The means of translation  39  have two positions ( FIGS. 4 and 5 ). Consequently, the first and second bearings  26  and  27  have the same two positions and, consequently, the top tool  16  and the anvil  17  have the same two positions. In a first position moved closer, the two tools  16  and  17  are arranged with respect to one another with an optimum radial gap  20 , and cooperate to realize the cutting function. In a second position moved away, the two tools  16  and  17  have a space between them and are capable of being modified by displacement of their rings  21  and  22  respectively. 
         [0060]    The translation means  39  are advantageously disposed between the first lateral bearing  26  and the third lateral bearing  29  so as to lift up the first lateral bearing  26 . The translation means  39  are advantageously disposed between the second lateral bearing  27  and the fourth lateral bearing  31  so as to lift up the second lateral bearing  27 . 
         [0061]    To do this, the translation means  39 , in a preferred manner, are in the form of a first front device  41 , in order to move the first bearing  26  away from the third bearing  27  by lifting, and conversely in order to move the first bearing  26  closer to the third bearing  27  by lowering. The translation means  39 , in a preferred manner, are in the form of a second rear device, in order to move the second bearing  27  away from the fourth bearing  31  by lifting, and conversely in order to move the second bearing  27  closer to the fourth bearing  31  by lowering. 
         [0062]    In the embodiment, the device  41  comprises a cylindrical rod  42  which is vertical, approximately parallel to the front ties  33  and centered with respect to the rotational axis  28  of the top tool  16  and with respect to the rotational axis  32  of the anvil  17 . The rod  42  is capable of sliding along a rectilinear vertical movement U and D, between the position moved closer and the position moved away and conversely between the position moved away and the position moved closer. The rod  42  carries out a maximum run (e in  FIG. 4 ) of sliding U. The rod  42  thus reaches a high point which corresponds to the desired and necessary gap between the top tool  16  and the anvil  17  so as to carry out the displacement of the two top rings  21  and  22 . 
         [0063]    One end or one top face  43  of the rod  42  abuts in an overall manner against a bottom face  44  of the first bearing  26 . A first obstructed, vertical, cylindrical housing  46  is arranged in a bottom part of the first bearing  26  and opens out at the bottom face  44  of said first bearing  26 . The bottom part of the rod  42  with the top end  43  is thus inserted into the first housing  46 . 
         [0064]    In a preferred manner, the device  41  comprises an eccentric  48 , positioned at the third bearing  29 . In order to obtain the sliding movement U and D, an end or a bottom face  47  of the rod  42  can bear on the eccentric  48 . A second cylindrical housing  49  is arranged in a top part of the third bearing  29  and opens out at the top face  51  of said third bearing  29 . The bottom part of the rod  42  with the bottom end  47  is inserted into the second housing  49 . The eccentric  48  is inserted to the bottom of the second housing  49 . 
         [0065]    The rod  42  is capable of being actuated manually, by rotating the eccentric  48 . The eccentric  48  is capable of turning (Arrows Tu and Td in  FIGS. 4 and 5 ) in a perpendicular manner with respect to the rod  42  and to the third bearing  29 , i.e. in this case horizontally. The device  41  comprises means for manually actuating the rod  42 . Said means comprise a shaft which is appreciably horizontal and extends the eccentric  48  and a rotary actuating knob  52  which is provided with a finger  53 , extending out of the outside face  54  of the third bearing  29 , and fixed to the shaft of the eccentric  48 . The rear device comprises the same constituent parts. 
         [0066]    According to the invention, a method for adjusting a radial gap  20  existing between two converting tools, the top tool  16  and the anvil  17 , in the converting arrangement, i.e. for cutting  14  the web  2 , comprises several successive stages. 
         [0067]    In a first stage, the operator releases the prestress by loosening the tightening elements, i.e. in this case the nuts  34  and  37 . The operator actuates the actuating knobs  52  by turning them Pu clockwise by half a turn and the eccentric  48  turns Tu in a corresponding manner (see  FIGS. 4 and 6 ). This causes the rod  42  to slide U upward and the first bearing  26  is directly pushed away along the predetermined distance, i.e. the gap e. In said second stage, the first bearing  26  is pushed away U from the third bearing  29  and the second bearing  27  is pushed away from the fourth bearing  31  along a predetermined distance e. The stage consisting in pushing the first bearing  26  away from the third bearing  29  and the second bearing  27  away from the fourth bearing  31  is implemented with two positions, one position moved closer in which the two tools  16  and  17  cooperate for the converting function, and one position moved away in which the lateral position of the ring or rings  21  and  22  is modifiable. 
         [0068]    The displacement U of the first bearing  26  thus creates the gap e between the top tool  16  and the anvil  17  so as to allow the radial gap  20  to be adjusted by subsequent displacement of one ring or of the rings  21  and  22 . In a third stage, the operator modifies a lateral position of one ring or of the two rings  21  and  22 . 
         [0069]    The operator actuates the actuating knob  52  by turning it Pd anticlockwise by half a turn (see  FIGS. 5 and 6 ), and the eccentric  48  turns Td in a corresponding manner. This causes the rod  42  to slide D downward, and the first bearing  26  to move closer. In a fourth stage, the first bearing  26  is moved closer to the third bearing  29  and the second bearing  27  is moved closer the fourth bearing  31 . Said displacement U of the first bearing  26  thus moves the top tool  16  closer to the anvil  17 , in order to allow the cutting function with the optimum radial gap  20  to be re-established. 
         [0070]    In a fifth and last stage, the operator re-establishes a prestress by retightening the tightening elements, i.e. the nuts  34  and  37 . 
         [0071]    The present invention is not limited to the embodiments described and illustrated. Numerous modifications can be realized without in any way departing from the framework defined by the scope of the set of claims.

Technology Category: 7