Patent Publication Number: US-6983903-B2

Title: Multi-functional shredder

Description:
FIELD OF THE INVENTION 
     The present invention relates to a multi-functional shredder, and in particular a shredder that has cutting elements suitable for cutting rigid or semi-rigid objects, such as CDs and DVDs, as well as paper. 
     BACKGROUND OF THE INVENTION 
     Shredders are well-known for use in shredding documents and other papers. Often, shredders are used for destroying outdated or extraneous documents, particularly those with confidential information. Typically, shredder designs have been directed specifically towards meeting the need for efficient, quiet, and effective shredding of paper, as that has been the traditional medium for storing information for many years. 
     With advances in information storage technology, many companies are storing information on computer mediums, and in particular recordable compact discs (CDs) and digital video discs (DVDs). CDs and DVDs allow a great deal of information to be stored in an extremely compact manner. Because CDs and DVDs are often used to store the same type of information as paper, it logically follows that businesses would still want to destroy CDs and DVDs containing confidential information. CDs and DVDs, however, are generally disc-shaped structures that are rigid, or at least semi-rigid, and the cutting elements typically used in shredders for cutting paper are not well-suited for effectively destroying such objects. Specifically, most shredders employ cutting elements having negative profiles because they have found to be the best for cutting paper. These negative profiles, however, tend to function poorly for cutting rigid/semi-rigid objects, such as CDs. 
     SUMMARY OF THE INVENTION 
     The present invention provides a multi-functional shredder that is capable of effectively destroying both paper documents and rigid/semi-rigid objects, such as CDs or DVDs. This multifunctional shredder comprises a housing; a drive system including at least one motor; and at least two shafts rotatably mounted within the housing and coupled to the drive system to enable the drive system to counter-drive the shafts in respective opposing rotational cutting directions. Each of the shafts includes positive cutter elements and negative cutter elements, configured to cooperate to shred articles as the shafts are rotationally counter-driven by the drive system in the respective rotational cutting directions thereof. The positive cutting elements on each shaft have positive cutting parts angled in the respective rotational cutting directions of the shafts, and the negative cutting elements on each shaft have negative cutting parts angled opposite the respective rotational cutting directions of the shafts. 
     Other objects, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a shredder; 
         FIG. 2  is a perspective view of a pair of shafts used in the shredder of  FIG. 1 , with both positive and negative cutting elements arranged thereon, the shafts being isolated from the remainder of the shredder; 
         FIG. 3  is an isolated perspective view of a positive cutting element on the shafts in  FIG. 2 ; 
         FIG. 4  is an isolated perspective view of a negative cutting element on the shafts in  FIG. 2 ; 
         FIG. 5  is a perspective view of one half of an exemplary positive cutting element; 
         FIG. 6  is a profile view of the half cutter element of  FIG. 5 ; 
         FIG. 7  is a radial view of the half cutter element of  FIG. 5 ; 
         FIG. 8  is a perspective view of the other half of an exemplary cutting element, which couples to the half of  FIG. 5 ; 
         FIG. 9  is a profile view of the half cutter element of  FIG. 8 ; 
         FIG. 10  is a radial view of the half cutter element of  FIG. 8 ; 
         FIG. 11  is a perspective view of another exemplary positive cutter element; 
         FIG. 12  is a profile view of the cutter element of  FIG. 11 ; 
         FIG. 13  is a radial view of the cutter element of  FIG. 11 ; 
         FIG. 14  is a profile view of an exemplary negative cutter element; and 
         FIG. 15  is a detailed view of subject matter in  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT OF THE INVENTION 
       FIG. 1  illustrates an example of a multi-functional shredder, generally indicated at  10 , constructed in accordance with the present invention. The shredder  10  includes a housing  12 , which may have any suitable configuration. The present invention is not limited to the one illustrated. By way of the example, the present invention may be incorporated into Model 480, 480CC and 480HS Powershred® shredders available from Fellowes, Inc., of Itasca, Ill., or any other type of shredder. Reference may be made to any one of the following U.S. patents for details concerning the general construction of a shredder: U.S. Pat. Nos. 5,071,080, 5,295,633, 5,511,732, 5,636,801, 6,260,780, 5,961,059, 5,655,725, 5,961,058, 5,954,280, 5,829,697, 5,826,809, 5,799,887, and 5,676,321, each of which is assigned to the assignee of the present application and hereby incorporated into the present application by reference. The shredder  10  also includes a drive system including at least one motor, which may be electrically powered. In the illustrated embodiment, only one motor is used. However, the drive system may have any number of motors, and may include one or more transmissions. 
     At least two shafts  18 ,  20  are rotatably mounted within the housing  12  and coupled to the drive system to enable the drive system to counter-drive the shafts in respective opposing rotational cutting directions. In  FIG. 2 , these counter-rotating directions would be the upper one rotating clockwise, and the lower one rotating counter-clockwise, thereby enabling cutter elements on the shafts  18 ,  20  to shred articles fed in the shafts  18 ,  20  and drive such articles down through the nip area defined between the shafts  18 ,  20 . Each of the shafts  18 ,  20  includes positive cutter elements  22  and negative cutter elements  24 . These cutter elements  22 ,  24  are configured to cooperate to shred articles as the shafts  18 ,  20  are rotationally counter-driven by the drive system in the respective rotational cutting directions thereof. 
     As best shown in  FIG. 3 , the positive cutting elements  22  on each shaft  18 ,  20  have positive cutting parts  26  angled in the respective rotational cutting directions of the shafts  18 ,  20 . Likewise, as best shown in  FIG. 4 , the negative cutting elements  24  on each shaft  18 ,  20  have negative cutting parts  28  angled opposite the respective rotational cutting directions of the shafts  18 ,  20 . As can be appreciated from the Figures, the positive cutting elements  22  have a body  23 , and the negative cutting elements  24  also have a body  25 . The positive cutting parts  26  extend radially from the body  23  and at their respective angles, and the negative cutting parts  28  extend radially from the body  25  and at their respective angles. 
     Preferably, but not necessarily, the positive cutting elements  22  on each shaft  18 ,  20  are arranged in at least one positive cutter element group  30  including a series of the positive cutting elements  22  arranged directly adjacent one another. Likewise, the negative cutting elements  24  on each shaft  18 ,  20  are arranged in at least one negative cutter element group  32  including a series of the negative cutting elements  24  arranged directly adjacent one another. The at least one positive element cutter group  30  and the at least one negative cutter element group  32  on one shaft  18  are arranged to cooperate with the at least one positive element cutter group  30  and the at least one negative cutter group  32 , respectively, on the other shaft  20  to shred articles as the shafts  18 ,  20  are rotationally counter-driven by the drive system in the respective rotational cutting directions thereof. Each shaft  18 ,  20  may include at least three of these groups  30 ,  32  arranged in alternating relation between the positive and negative cutter element groups  30 ,  32 . However, any number and any specific arrangement of groups may be used. In the illustrated embodiment, as best shown in  FIG. 2 , these groups includes one positive cutter element group  30  disposed generally centrally on each shaft  18 ,  20  and two negative cutter element groups  32  on opposing sides of the positive cutter element group  30 . The cutter elements  22 ,  24  in these groups  30 ,  32  are arranged helically to ensure even cutting. The present invention, however, is not intended to be limited to the embodiment illustrated and is intended to encompass a wide range of variations. For example, the positive and negative elements  22 , 24  could be alternated along the shafts  18 , 20  and need not be grouped together. 
     As seen in  FIG. 3 , each positive cutting element  22  preferably has a plurality of the positive cutting parts  26 , and as seen in  FIG. 4 , each negative cutting element  24  has a plurality of the negative cutting parts  28 . Preferably, each positive cutting part  26  terminates in at least one sharp leading point  34  for piercing articles being shredded. That is, the point  34  leads the part  26  in the rotational cutting direction so as to lead the piercing action into the article being shredded. This is particularly useful for destroying rigid/semi-rigid articles, such as CDs and DVDs. Specifically, the piercing action helps to break up these types of articles into and through the interface of the counter-rotating elements. In the illustrated, exemplary embodiment of  FIG. 3 , each positive cutting part  26  terminates in a pair of such sharp points  34  for piercing articles being shredded. It is within the scope of the invention to use only one point per cutting part, or to use more than two points per cutting part, such as a three or four-pointed cutting part. 
       FIGS. 5–10  illustrate one exemplary positive cutter element  22 . Specifically,  FIGS. 5–7  illustrate one half  22   a  of the element  22  and  FIGS. 8–10  illustrate the other half  22   b . The halves are coupled by pins  33  on half  22   a  that are received in openings  35  in the other half  22   b  to rotationally lock them together. The halves  22   a  and  22   b  are otherwise mirror images and couple together to form the cutter element  22  illustrated in  FIG. 3 . The cutter element halves  22   a ,  22   b  are preferably formed by stamping or casting, but could also be formed by machining. 
       FIGS. 11–13  illustrate another exemplary positive cutter element  22 , but made from one piece of metal, preferably by stamping. 
     As best seen in  FIG. 4 , each negative cutting part  28  preferably includes at least one sharp cutting edge  36  angled opposite the respective rotational cutting directions of the shafts  18 ,  20  for slicing articles being shredded. As opposed to a positive cutting profile, this negative cutting profile is more efficient and effective for cutting flexible materials, such as paper. In the illustrated embodiment, each negative cutting part  28  includes two such sharp cutting edges  36  angled opposite the respective rotational cutting directions of the shafts  18 ,  20  for slicing articles being shredded. As with the positive cutter parts  26  of the positive cutter element  22 , each negative cutter part  28  may have more or less than two cutting edges  36  (e.g. one, or three or more). 
       FIGS. 14 and 15  show details of a profile for an exemplary negative cutter element  24 . The profile shown may be applied to a one-piece element  24 , which is what is depicted in  FIGS. 14 and 15 . Moreover, the structure in  FIGS. 14 and 15  could also be one-half of a cutter element and be coupled to another mirror image half, as is the case with the positive cutter element as shown in  FIGS. 5–10 . The negative cutter element  24  could be formed by stamping or casting, or also by machining. 
     It should be understood the cutter element profiles illustrated herein are intended only to be examples and in no way limit the breadth of the invention. 
     Any suitable construction may be used to affix the cutter elements  22 ,  24  to the cutter shafts  18 ,  20 , or the cutter elements  22 ,  24  may be integrally formed on the shafts  22 ,  24 . As an exemplary way of attaching cutter elements  22 ,  24  to the shafts  18 ,  20 , each cutter element  22 ,  24  may be provided with an interlocking structure  38  thereon. Each shaft  18 ,  20  may be a hollow shaft defined by a substantially tubular wall  40  and the tubular walls  40  of the shafts  18 ,  20  may be diametrically expanded to securely engage the tubular walls  40  with the interlocking structures  38  on the cutter elements  22 ,  24  to thereby secure the cutter elements  22 ,  24  on the shafts  18 ,  20 . The tubular walls  40  of the shafts  18 ,  20  may be diametrically expanded to form protruding portions (not shown) on opposing sides of each cutter element  22 ,  24  to thereby secure the cutter elements  22 ,  24  against axial movement on the shafts  18 ,  20 . Further, the interlocking structure  38  of each cutter element  22 ,  24  may be a series of teeth  42  on an internal opening of each cutter element  22 ,  24  sized to receive the shafts  18 ,  20  therein. Further details of this exemplary way of attaching the cutter elements are discussed in U.S. Pat. No. 5,799,887, the entirety of which is incorporated into the present application. 
     Alternatively, the shafts  18 ,  20  could have polygonal cross-sections (such as a regular hexagon) and the cutter elements  22 ,  24  could have matching polygonal internal openings for receiving the shafts. This would rotationally lock the cutter elements  22 ,  24  on the shafts  18 ,  20 . 
     The foregoing detailed description has been provided solely to illustrate the functional and structural principles of the present invention, and is not intended to be limiting. To the contrary, the present invention is intended to encompass all variations, modifications, substitutions, and alterations within the spirit and scope of the appended claims.