Abstract:
A punching apparatus for forming a series of slots in a board, comprising: an upper wheel and a lower wheel, wherein the upper wheel is opposed to the lower wheel, and further wherein: the upper wheel comprises a series of punches disposed on a frame of the upper wheel, wherein each punch comprises a shearing portion that extends from the frame, and which is configured in the shape of a slot; and the lower wheel comprises a series of mating dies, wherein each mating die of the series of mating dies comprises a cavity, wherein the shearing portion of a particular punch is gradually disposed within the cavity of a particular mating die of the series of mating dies as the upper wheel and the lower wheel move in relation to each other.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/747,629 filed on May 18, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally related to an apparatus for punching. More particularly, this invention is related to an apparatus for punching slots into profiled cellular polyvinylchloride (cellular PVC) boards, wherein an exemplary application of such punched, profiled cellular PVC is in the use as siding. 
     2. Background of the Invention 
     This invention relates to a novel apparatus for punching slots into profiled cellular PVC boards to be used as siding. Slot punching of cellular PVC boards at the required production throughput rate demands an entirely unique approach to achieve the required slot punching accuracy as compared to prior art punching apparatuses used to punch traditionally used rigid vinyl siding materials. 
     Conventional high speed rigid rotary vinyl siding slot punching consists of a single rotary punching wheel, combined with two lower stationary side cutting blades. This conventional arrangement is typically located just downstream of the extruder on a vinyl siding extrusion line, punching through just extruded, warm vinyl. The geometry of this conventional arrangement shears the slot sides but does not perform actual punch/die shearing of the slot ends. In warm, newly extruded vinyl, this lack of shearing of the slot ends does not pose a problem and slots are punched with relatively clean slot ends. 
     Profiled cellular PVC boards are milled from previously extruded cellular PVC sheets. The material has been cured and is therefore harder and more brittle than warm cellular PVC. Profiled cellular PVC boards punched with the above described conventional arrangement, show significant breakage along the shear line, uneven cuts and structural fractures in the slot vicinity due to not fully shearing the entire slot. Therefore, the conventional slot punching arrangement is totally inadequate for forming slots in cellular PVC boards. Accordingly, a new approach is needed that would punch slots in cellular PVC material at the required rates, wherein all of the exposed sides of the slot are sheared. Additionally, specially contoured and coated tooling is required when punching cellular PVC material due to its highly abrasive qualities, as compared to conventional vinyl siding material. 
     BRIEF SUMMARY OF THE INVENTION 
     The foregoing needs have been satisfied by the development of a unique rotary type slot punching apparatus of extreme speed, precision and robustness that incorporates unique and innovative cellular PVC processing techniques such as special tooling design and coatings and electrostatic charge abatement. More particularly, the present invention incorporates a unique approach to siding slot punching by utilizing two opposed, precision, counter-rotating wheels: the upper wheel having punches and the lower wheel having a series of mating dies complementary to the punches in the upper wheel. These punches and their mating dies incorporate cutting edges on the entire periphery of the slot shape thereby providing full shearing of the entire slot including the ends. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic depicting an elevation view of an exemplary punching apparatus; 
         FIG. 2  is a schematic depicting an in-feed end view of an exemplary punching apparatus; 
         FIG. 3  is a schematic depicting a detail of the slotting process; and 
         FIG. 4  is a schematic depicting an exemplary cellular PVC board. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The punching apparatus of the present invention forms slots in boards, wherein an exemplary use of the slotted boards is as siding material. Although the boards may comprise a variety of materials, in an especially preferred embodiment the board comprises cellular PVC. The inventive punching apparatus offers a novel approach for the formation of slots in the nailing flange area of the board, wherein the punching apparatus is designed to shear all of the exposed sides of the slot, and not merely just the slot&#39;s lateral sides as is done in conventional punching operations. To accomplish this, the inventive punching apparatus comprises a plurality of punches disposed about a frame of an upper wheel. Each of the punches forming the plurality comprise a shearing portion that extends from the frame, and which is configured to fit within a cavity of a respective mating die located on a lower wheel. The shearing portion comprises a geometrical shape and size to match that of the desired geometrical shape and size of the slot to be formed in the board. The board is disposed between the upper and the lower wheels. Therefore, as the upper and lower wheels continuously rotate, thereby causing the shearing portion of the punch to progressively enter the cavity of the mating die, the shearing portion progressively punches through the board leaving a slot having the same configuration as the punch. Continuous rotation of the upper wheel and the lower wheel as the board drives through the punching apparatus results in the formation of a slotted board having improved working characteristics as compared to boards formed using traditional punching methods. 
     An exemplary punching apparatus and punching operation will be discussed below with reference to the figures. However, it is to be understood that the invention shall not be limited to the exemplary embodiments depicted in the figures, but that it shall include all obvious modifications and variations thereto that would occur to one of ordinary skill in the art. 
     Referring to  FIGS. 1-3 , a profiled cellular PVC board  12  may be longitudinally fed into an exemplary punching apparatus  10  in continuous motion fashion, lying flat. Punching apparatus  10  comprises a uniquely designed nip roll drive  14  and a rotary punch and die mechanism  16 . 
     In an exemplary embodiment, nip roll drive  14 , which is powered and synchronized by rotary punch and die mechanism  16 , through timing belts  23  and  24 , preferably comprises two lower drive wheels  18  and  19  and two articulated upper pressure wheels  20  and  21 . In an exemplary embodiment, lower drive wheels  18  and  19  are hardened and comprise ground tool steel, and articulated upper pressure wheels  20  and  21  are urethane coated, wherein the urethane coating provides an excellent compromise between grip, damage protection, and wear. 
     Upper pressure wheels  20  and  21  may be actuated by adjustable compression springs  17 . Lower drive wheels  18  and  19 , which are powered by a gear motor  22  via a timing belt  24 , work in concert with upper pressure wheels  20  and  21  to firmly grasp and propel cellular PVC board  12  between an upper wheel  26  and a lower wheel  28  of rotary punch and die mechanism  16 . This drive preferably incorporates a datum fence  36  to accurately align and position cellular PVC board  12  for punching. Cellular PVC board  12  may be kept in constant contact with datum fence  36  by an opposing adjustable guide fence  38 . In operation, the cellular PVC boards will preferably enter the punching area in continuous motion fashion. 
     As previously mentioned, rotary punch and die mechanism  16  comprises upper wheel  26  and lower wheel  28 , wherein upper and lower wheels  26  and  28  oppose each other, and wherein, in combination, upper and lower wheels  26  and  28  perform the actual physical punching operation. In an exemplary embodiment, each of upper and lower wheels  26  and  28  comprises a diameter of approximately 11 inches. 
     In an exemplary embodiment, upper wheel  26  comprises a plurality of specially coated and contoured punches  30  equally spaced around an outer periphery  60  of a frame  48  of upper wheel  26 . Each punch  30  comprises a shearing portion  40  which extends outwardly from frame  48  such that an outer edge  52  of frame  48  is recessed in relation to shearing portion  40 . Shearing portion  40  is configured in the shape of the slot to be formed in cellular PVC board  12 . For example, to form a slot  13  as depicted in  FIG. 4 , shearing portion  40  of punch  30  comprises an identical geometry to that of slot  13 . As the entire slot is formed by a single punch  30 , all of the exposed sides  15  of slot  13  would be properly sheared upon formation of slot  13 . In an exemplary embodiment, plurality of punches  30  comprises about 20 individual punches. 
     Additionally, in an exemplary embodiment, lower wheel  28  comprises a plurality of specially coated mating dies  32  equally spaced around an outer periphery  58  of a frame  54  of lower wheel  28 . Each of mating dies  32  comprises an upper boundary  46  that is recessed relative to an outer edge  56  of frame  54 . Additionally each of mating dies comprises a lateral edge  42  opposite to a lateral edge  44 , wherein upper boundary  46  is disposed therebetween such that a portion  48  and  50  of respective lateral edges  42  and  44  extends above top edge  46 , thereby causing formation of a cavity  33 . Lateral edges  42  and  44  are preferably flush with outer edge  56 . Preferably, the number of mating dies forming plurality of mating dies  32  is equal to the number of punches forming plurality of punches  30 . 
     Upper and lower wheels  26  and  28  are preferably synchronized by a set of precision, anti-backlash gears  34 , which may be powered by electric-driven gear motor  22  and timing belt  23 . It is preferable that anti-backlash gears  34 , upper wheel  26 , and lower wheel  28  have approximately the same diameter to provide precise synchronization of the punching process. 
     Referring to the figures, cellular PVC board  12  is disposed between upper wheel  26  and lower wheel  28  and between articulated upper pressure wheels  20  and  21  and lower drive wheels  18  and  19 . Referring to  FIGS. 3 and 4 , as upper and lower wheels  26  and  28  rotate in continuous fashion, and as cellular PVC board moves forward between upper and lower wheels  26  and  28 , shearing portion  40  from a punch  30 ′ progressively enters cavity  33  of mating die  32 ′, thereby progressively piercing cellular PVC board  12  in a nailing flange area  11  of board  12 . The progressive piercing of cellular PVC board  12  causes a slot blank  29  to be carved from cellular PVC board  12 . Once completely carved from cellular PVC board  12 , slot blank  29  is removed from mating die  32  by gravitational force. Slot blank  29 , therefore, is replaced by the formation of a slot  13  in cellular PVC board  12 , wherein slot  13  is shaped to the configuration of shearing portion  40 . Once slot  13  is formed, and as rotation of upper and lower wheels  26  and  28  continues, shearing portion  40  is lifted out of cavity  33 , wherein the punching process will continue with punch  30 ″ and mating die  32 ″. 
     The unique, continuous, rotary motion slot punching apparatus of the present invention will allow punching rates of up to approximately 1,400 slots per minute. Given the required slot spacing, this punching rate will allow the punching process to meet a desired product flow of at least about 200 feet per minute in a continuous motion, inline fashion. Thus, the slot punching throughput of this single apparatus will satisfy projected production requirements without the need for like parallel processes. 
     An exemplary punching process utilizing the inventive punching apparatus disclosed herein will be described with reference to the figures, wherein it is again to be appreciated that the process may include obvious variations and modifications thereto. Additionally, although the terms “clockwise” and “counterclockwise” are used to give a sense of orientation, it is to be understood that the directions of rotation may be the reverse of those stated. 
     Referring to  FIG. 1 , timing belt  24  is circuitously attached to lower wheel  28 , lower drive wheel  18 , and lower drive wheel  19  (i.e., timing belt  24  is disposed over a hub  31  of lower drive wheel, over a hub  37  of lower drive wheel  19 , over a hub  41  of an intermediate wheel  35 , and over a hub  27  of lower wheel  28 ). Rotational movement of lower wheel  28  causes movement of timing belt  24  over the various hubs, thereby causing the counterclockwise movement of lower drive wheel  18  and lower drive wheel  19 . Additionally, compression springs  17  drive the rotational movement of respective articulated upper pressure wheels  20  and  21 . Though the efforts of timing belt  24  and compression springs  17 , board  12  is driven though punching apparatus  10 . 
     As board  12  is driven through punching apparatus  10 , lower wheel  28  and upper wheel  26  are rotated relative to each other to form slots in board  12 . The rotational movement of lower wheel  28  is ultimately accomplished by a gear motor  22 . When activated, e.g., turned on, gear motor  22  drives the counterclockwise rotation of a motorized wheel  25 . Via timing belt  23 , which is attached to a hub  39  of motorized wheel  25  and to a hub  27  of lower wheel  28 , the counterclockwise rotational movement of motorized wheel  25  causes lower wheel  28  to rotate in a counterclockwise direction. 
     The counterclockwise rotational movement of lower wheel  28  drives the clockwise rotational movement of upper wheel  26 . That is, referring to  FIG. 3 , as lower wheel  28  rotates, and as a greater portion of shearing portion  40  of punch  30 ′ is exposed to cavity  33  of mating die  32 ′, a gravitational force pulls shearing portion  40  of punch  30 ′ into cavity  33  of mating die  32 ′. As lower wheel  28  continues to rotate, portion  50  of lateral edge  44  of mating die  32 ′ pushes against an edge  62  of shearing portion  40  of mating die  32 ′, thereby causing the rotation of upper wheel  26  in an oppositely directed rotational motion. Such push continues until outer edge  52  of upper wheel  26  abuts outer edge  56  of lower wheel  28 . An edge  64  of sharing portion  40  of punch  30 ″ then pushes against portion  48  of lateral edge  42  of mating die  32 ″ to continue the rotation. The process continues until the power from gear motor  22  is deactivated. 
     In this manner, then, cellular PVC board  12  is driven through punching apparatus  10 , and slots are evenly formed and distributed on cellular PVC board  12 . Furthermore, as shearing portions  40  are configured in the shape of the slot, the process allows for the formation of slots having all of their exposed sides completely sheared in a single operation. This then, creates an improved product for the use of siding as the improved resulting clapboard shows significantly reduced breakage along the shear line, and significantly reduced uneven cuts and structural fractures in the slot vicinity. 
     Although the principles of the present invention have been illustrated and explained in the context of certain specific embodiments, it will be appreciated by those having skill in the art that various modifications beyond those illustrated can be made to the disclosed embodiment without departing from the principles of the present invention.