Abstract:
A rotary cutter includes a hollow rotary mantle having a cutter arbour on an outer periphery thereof, through holes extending radially through the mantle, and an air distribution mechanism. The air distribution mechanism includes first and second parts. The first part is affixed to the mandrel coaxially therein for rotation therewith. The second part is arranged inside the first part, wherein the first distribution part is rotatable relative to the second distribution part. The first and second air distribution parts define air passages for communicating selective ones of the through-holes of the mantle with an air source in response to relative rotation between the first and second distribution parts.

Description:
[0001]     The present application claims priority under 35 U.S.C. § 119 to Patent Application Serial No. 0402666-2 filed on Nov. 3, 2004 and Patent Application Serial No. 0401734-9 filed on Jul. 2, 2004 in Sweden, respectively.  
       TECHNICAL BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to an air distribution assembly for a rotary cutting apparatus having a shaft and a mantle, the mantle having at least one cutting member.  
         [0003]     The invention also relates to a rotary cutting apparatus provided with such an air distribution assembly.  
         [0004]     Air distribution in a rotary cutting apparatus is previously known and is performed by radial bores formed in the circumferential surface of a solid rotary cutter. Axial bores connect the radial bores with sources of vacuum and/or atmospheric pressure or over-pressure. Drilling of such axial and radial bores is time consuming and expensive, in particular since they have to be made with high accuracy.  
         [0005]     U.S. Pat. No. 4,770,078 discloses in a discussion of the prior art ( FIGS. 1-3 ) a one piece rotary cutter, which has to be removed from the frame when maintenance is needed. In order to allow the machine to be used during maintenance, a further rotary cutter including its static shaft must always be accessible.  
         [0006]     In order to overcome that problem, U.S. Pat. No. 4,770,078 suggests to divide the rotary cutter into a rotatable shaft and a mantle. The mantle is connected to the rotatable shaft by means of pneumatic pressure. A drawback with this kind of rotary cutter is that it is difficult to index the rotary cutter relative to the anvil. Another drawback is the lack of support of the rotary cutter on the side opposite to the driven side.  
       SUMMARY OF THE INVENTION  
       [0007]     An object of the invention is to provide the known rotary cutter with a simplified connection to sources of vacuum and/or atmospheric pressure or over-pressure.  
         [0008]     This has been achieved by the air distribution assembly of the initially defined kind, which comprises a first air distribution part adapted to rotate together with said mantle and a second air distribution part adapted to be connected to the center shaft.  
         [0009]     Preferably, said first air distribution part is provided with openings adapted to correspond to through holes of said mantle and wherein said second air distribution part is provided with openings adapted to at least intermittently correspond to the openings of said first air distribution part. Hereby is achieved a simplified distribution of air to the exterior of the surface of the rotary cutter.  
         [0010]     More particularly, said first air distribution part is provided with at least one first opening adapted to correspond to through holes of the mantle intended to influence a region of the mantle relating to the residues of a cut sheet or the sheet to be cut, and at least one second opening adapted to correspond to through holes of the mantle intended to influence a region of the mantle regarding the cut article or the article to be cut.  
         [0011]     Alternatively, only the region comprising the first or the second opening is influenced.  
         [0012]     In addition, said second air distribution part is provided with at least one third opening adapted to at least intermittently correspond to said first opening, said third opening being associated with a source of vacuum.  
         [0013]     Suitably, said second air distribution part is provided with at least one fourth opening adapted to at least intermittently correspond to said second opening, said fourth opening being associated with a source of vacuum.  
         [0014]     Alternatively, said second air distribution part is provided with at least one third opening adapted to at least intermittently correspond to said first opening and/or to said second opening, said third opening being associated with a source of vacuum;  
         [0015]     Suitably the radial peripheral surface of the second air distribution part is provided with a groove.  
         [0016]     Hereby are achieved different possibilities of controlling the air flow from different through-hole on the surface of the rotary cutter.  
         [0017]     Preferably, said second air distribution part is provided with at least one fifth opening for influencing a region of the mantle regarding the region of the mantle regarding the cut article and/or the residue of the cut sheet, said fifth opening being associated with atmospheric pressure or a source of over-pressure.  
         [0018]     Suitably, the radial peripheral surface of the second air distribution part is provided with a groove for performing the influence to the region of the mantle regarding the cut article and the residue of the cut sheet.  
         [0019]     Hereby are achieved different possibilities of controlling the air flow to different through-hole on the surface of the rotary cutter.  
         [0020]     Advantageously, said first air distribution part is adapted to be arranged radially peripheral to that of said second air distribution part.  
         [0021]     In particular, said first air distribution part is substantially circular cylindrical and said second air distribution part is substantially circular cylindrical, and wherein said first and second air distribution parts are coaxially arranged in a rotatable interrelationship.  
         [0022]     Hereby, a suitable shape of the air distributor parts is achieved.  
         [0023]     Preferably, at least one of said shafts is hollow and is associated with a source of vacuum, said second air distribution part being associated with said hollow shaft.  
         [0024]     Hereby is achieved a simple and efficient air distribution to the exterior of the rotary cutter.  
         [0025]     This has been achieved by a rotary cutter and a rotary cutting apparatus of the initially defined kind, wherein the shaft is adapted to be rigidly mounted in a frame part, and wherein the mantle is rotatably arranged relative to the shaft. Hereby, indexing of the mantle relative to the shaft is made easier, since the mantle can be rotated relative to the static shaft. Furthermore, it is only necessary to perform maintenance of the mantle, i.e. the shaft can be used together with another mantle such that the production can be continued while maintenance is performed on the worn mantle.  
         [0026]     Preferably, the mantle is adapted to be connected to a power source for creating a rotational movement of the mantle.  
         [0027]     Preferably bearings are provided between the mantle and the shaft. Hereby, a controlled positional and rotational relationship between the static shaft and the mantle is achieved.  
         [0028]     Suitably, a power transmission means is provided for transmitting the rotational movement to said mantle.  
         [0029]     Advantageously, the mantle has an axial extension and opposite axial ends, wherein said mantle is adapted to be supported by the shaft and connected to the power source in the region of one of the ends of said mantle, and wherein said mantle is adapted to be supported by the shaft in the region of the opposite end.  
         [0030]     Alternatively, said shaft is divided into a first and a second shaft member, the mantle having an axial extension and opposite axial ends, wherein said mantle is adapted to be supported by the first shaft member and connected to the power source in the region of one of the ends of said mantle, and wherein said mantle is adapted to be supported by the second shaft member in the region of the opposite end.  
         [0031]     Advantageously, the frame part of the rotary cutting apparatus further comprises a fastening means for said shaft and a power transmission connection means for said mantle.  
     
    
     DRAWING SUMMARY  
       [0032]     In the following, the invention will be described in greater detail by reference to the accompanying drawings, in which  
         [0033]      FIG. 1  illustrates a rotary cutting apparatus comprising an anvil and a cross-section of a rotary cutter according to a first embodiment of the invention;  
         [0034]      FIG. 2  is a cross-section of a second embodiment of the rotary cutter;  
         [0035]      FIG. 3  is a cross-section of a third embodiment of the rotary cutter;  
         [0036]      FIGS. 4A and 4B  is an exploded view and an axial cross-section of the first embodiment, provided with an air distribution assembly;  
         [0037]      FIGS. 5A and 5B  are cross-sections in part of the air distribution assembly shown in  FIG. 4B  provided with first and a second air distribution parts;  
         [0038]      FIG. 5C  is a perspective view of the second air distribution part;  
         [0039]      FIGS. 6A and 6B  are cross-sections in part of alternative air distribution assemblies; and  
         [0040]      FIGS. 7A and 7C  illustrate the air distribution parts and the mantle in different angular positions. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0041]      FIG. 1  shows a rotary cutting apparatus  2 , comprising a rotary cutter  4  and an anvil roll  6 . The rotary cutter  4  comprises a divided static (stationary) shaft  8 , comprising axially spaced shaft members  8   a ,  8   b , each member being rigidly connected to a respective frame part  10   a ,  10   b  by means of screws  12 . A drive axle  14  is associated with a not-shown power source for transmitting a rotational movement to a tool in the form of a mantle  16  via an intermediate transmission member  18   a . The rotational movement is further transmitted to a rotational support  18   b . Cylindrical bearings  19  are provided between the shaft members  8   a ,  8   b  and the intermediate transmission members  18   a ,  18   b , respectively, for centering the mantle  16  relative to the shaft members  8   a ,  8   b . The frame parts  10   a ,  10   b  are secured to the rest of the frame by means of suitable, not-shown fastening means. The mantle  16  is provided with at least one cutting member  17  (See  FIG. 4A ) which is endless so as to be able to cut an article from a sheet.  
         [0042]     During disassembly, the frame parts  10   a ,  10   b  are unsecured from the rest of the frame such that the static shaft members  8   a ,  8   b  including the transmission members  18   a ,  18   b  can be pulled out from the mantle  16 . The mantle  16  is taken away and maintenance can thus be performed. Another mantle.  16  is mounted in place of the other one, and the rotary cutting device can be utilised without long stoppage.  
         [0043]     Of course, it may be enough to take away either of the static shaft members  8   a  and  8   b , respectively, rather than both.  
         [0044]      FIG. 2  shows a second embodiment of a rotary cutting apparatus  2 ′ and rotary cutter  4 ′. The cross-section is such that the cutting member  17 ′ has been omitted, but is of course present (see  FIG. 4 ). The static shaft  8 ′ is in this case a single part and is connected to the frame  10 ′ on either side of the mantle  16 ′ by screws  12 ′. The rotational movement of the drive axle  14 ′ is transmitted to the mantle  16 ′ via a gear train  20   a ′,  20   b ′,  20   c ′,  20   d ′. It should be noted that the parts  20   b ′,  20   c ′,  20   d ′ could be produced as two pieces or even one single piece. Centering is performed by means of cylindrical bearings  19 ′.  
         [0000]     During disassembly, the frame part  10   b ′ in the right part of  FIG. 2  is unsecured from the rest of the frame (i.e. the left frame part remains secured). The mantle  16 ′ can then be pulled away from the shaft  8 ′.  
         [0045]      FIG. 3  shows a third embodiment of a rotary cutting apparatus  2 ″ and a rotary cutter  4 ″. Also in this case, the cross-section is such that the cutting member has been omitted. The drive axle  14 ″ transmits rotational movement directly to the mantle  16 ″ via a coupling member  22 ″. The static shaft  8 ″ is divided into two shaft members  8   a ″,  8   b ″ connected to the frame parts  10   a ″,  10   b ″ on either sides of the mantle  16 ″. The mantle  16 ″ is centered relative to the shaft members  8   a ″,  8   b ″ and the driving axle  14 ″ by means of conical bearings  24 ″.  
         [0046]     For maintenance purposes, the shaft member  8   b ″ is unsecured from the frame parts  10   a ″,  10   b ″, and then the mantle  16 ″ is released from the shaft member  8   a ″.  
         [0047]     The mantle  16 ,  16 ′,  16 ″ may be made of a multiphase material, such as steel, cemented carbide or cermet (hard phase bonded by a metal).  
         [0048]      FIG. 4A  shows a rotary cutting apparatus  2 ′″ and a rotary cutter  4 ″″ similar to the first embodiment (see  FIG. 1 ), so the same reference numerals designating the same elements as in  FIG. 1  will be used in  FIG. 4A . A major difference between the embodiments of  FIGS. 1 and 4 A is that in  FIG. 4A  the rotary cutter  4 ′″ is provided with an air distribution assembly  30  which comprises a first air distribution part  32 , a second air distribution part  34 , an air connection piece  36  and said shaft member  8   b ′″, now hollow, for interconnecting the second air distribution part  34  and said air connection piece  36 . The air connection piece  36  is connected to a section of an air source  35 , namely to a source of vacuum pressure  35   a  (see  FIG. 4A ).  
         [0049]     The first and second air distribution parts  32 ,  34  may be made of a polymer, a metal, a hard metal or ceramics. It is however not necessary that the parts  32  and  34  be made of the same material.  
         [0050]     As already stated above, cylindrical bearings  19  are provided between the shaft members  8   a ,  8   b ′″ and the intermediate transmission members  18   a ,  18   b , respectively, for centering the mantle  16  relative to the shaft members  8   a ,  8   b′″.    
         [0051]     The mantle  16  is connected to the first air distribution part  32  by press-fit, fastening means or gluing, whereas the second air distribution part  34  is connected to the connection piece  36  shaft member  8   b ′″, preferably by a fastening means. Thus, during operation the first air distribution piece  32  rotates together with the mantle  16 , whereas the second air distribution piece  34  is static.  
         [0052]     The mantle  16  is provided with first through-holes  40  outside the cutting member  17  and second through-holes  42  inside the cutting member  17 . The reason for this will be explained further below.  
         [0053]      FIG. 4B  shows the assembled rotary cutter  4 ′″, the mantle  16  and the first and second distribution parts  32 ,  34  being coaxially arranged. First and second openings  44  and  46  in the first distribution part are provided for connection to respective through-holes  40 ,  42  (see  FIG. 4A ) of the mantle  16 . The first and second distribution parts  32 ,  34  are hollow and substantially circular cylindrical in shape. During operation, the second distribution part  34  defines a coaxial lumen  47  which connects to the interior of the air connection piece  36 , which in turn is connected to the source of vacuum pressure  35   a.    
         [0054]     A connector  49   a  is connected to another section of the air source  35 , namely a source of pressure  35   b  which is at least at atmospheric pressure  35   b , i.e., atmospheric pressure or an over-pressure. A bore  49   b  connects the connector  49   a  with a substantially radial bore  49   c  of the second air distribution part.  
         [0055]     In  FIG. 5A , a portion of the first distribution part  32  has been cut away and shows in that relative position of the first and second air distribution parts  32 ,  34 , how the first openings  44  connect to a third opening  48  of the second distribution part  34 . The third opening  48  connects in turn to the lumen  47 .  
         [0056]     In  FIG. 5B , a further portion of the first distribution part  32  has been cut away and shows how the second openings  46  connect to a fourth opening  50  of the second distribution part  34 . The fourth opening  50  connects in turn to the lumen  47 .  
         [0057]     Furthermore, in the rotational direction after the fourth opening  50 , a groove  52  is provided in the second distribution part  34 . A longitudinal portion  52   a  thereof connects to the second openings  46 , whereas a circumferential portion  52   b  continues in the circumferential direction of the second air distribution part  34 .  
         [0058]     As can be seen in  FIG. 5C , the circumferential portion  52   b  of the groove  52  continues with a further longitudinal portion  52   c  and continues with a substantially radial bore  49   c , which in turn is connected to the connector  49   a  via the bore  49   b  (see  FIG. 4B ).  
         [0059]     The size of the second opening  46  is substantially constant in order to fit the size of the fourth opening  50 . However, in order to fit the form of the article to be cut, i.e. the shape of the knife member  17 , an axial groove  54  is arranged in the surface of first distribution part  32 .  
         [0060]     In the same manner, the size of the second opening  44  is substantially constant in order to fit the size of the third openings  48 , and in order to fit the form of the residue of the sheet, i.e. also in this case the shape of the knife member  17 , an axial groove  56  is arranged in the surface of first distribution part  32 .  
         [0000]     In  FIG. 6A , an alternative embodiment of a second distribution part  34   a  is presented, according to which the third and fourth openings  48 ,  50  have been interconnected by a longitudinal groove  60 .  
         [0061]     In  FIG. 6B , the groove  60  is a radial opening, i.e. it projects radially through the part  34   a , whereby the openings  48 ,  50 ,  60  form a single opening.  
         [0062]      FIGS. 7A-7C  illustrate how the openings of the air distribution parts  32 ,  34  correspond to the through-holes of the mantle  16  in different relative positions.  
         [0063]     Consequently, in  FIG. 7A  broken lines A and B indicate different circumferential positions of the first and second air distribution parts  32 ,  34  and the mantle  16  of a pre-determined angular position of the first and second air distribution parts.  
         [0064]     The through-holes  40  outside the knife member  17  are connected to the third openings  48  via the first openings  44  along the line A. Similarly, the through-holes  42  along line B and inside the knife member  17  are connected to the fourth opening  50  via the second openings  46 .  
         [0065]     Consequently, the through-holes  40  as well as the through-holes  42  will be subjected to a vacuum.  
         [0066]     In  FIG. 7B  is shown that the through-holes  42  along the line C are connected to the groove  52 , whereas the through-holes  40  along the lines D are connected to third openings  48 .  
         [0067]     Thus, the through-holes  40  will remain subjected to a vacuum, whereas the through-holes  42  will be subjected to atmospheric pressure or an over-pressure.  
         [0068]     However, at line E, also the through-holes  40  along the line E will also be subjected to atmospheric pressure or an over-pressure.  
         [0069]     It should be noted that along lines F, the openings  46  are closed, i.e they do not face an opening or a groove in the second air distribution member  34 .  
         [0070]     In  FIG. 7C  is shown that along lines G, the openings  44  as well as the openings  46  are closed.  
         [0071]     Thus, during cutting of a sheet, e.g. a web, a cardboard or a metallic foil, and due to vacuum distributed to predetermined through-holes  40  and  42  (see the lines A and B in  FIG. 7A ), the whole sheet will stick to the surfaces both outside and inside the knife member  17 , while the knife-member cuts against the anvil roll  6  (see  FIG. 1 ).  
         [0072]     After cutting the article, the mantle  16  and the first air distribution part  32  has rotated away from the contact with the anvil roll  6 , and to another position of the second air distribution part  34  (see the lines C in  FIG. 7B ). The article will come loose from the mantle  16 , due to atmospheric pressure or over-pressure distributed to the same predetermined through-holes  42 , whereas the rest of the sheet will stick to the mantle  16 , due to the vacuum distributed to the same predetermined through-holes  40 . A slight further rotation will cause the openings  46  to close (see the lines F in  FIG. 7B ).  
         [0073]     Further rotation of the mantle  16  and the first air distribution part  32  relative to the anvil roll  6  and to the second air distribution part  34  will cause also the rest of the sheet to come loose from the mantle  16 , since the same predetermined through-holes  40  will then be subjected to atmospheric pressure or an over-pressure (see line E in  FIG. 7B ).  
         [0074]     A slight further rotation will cause the openings  46  and then the openings  44  to close (see line G in  FIG. 7C ).  
         [0075]     With minor modifications of the rotary cutter shown in  FIG. 2 , it would also be possible to use the air distribution parts  32 ,  34  in that embodiment.  
         [0076]     Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.