Abstract:
A device for consecutively forming one or more notches in a first surface and one or more notches in second surface of a hollow workpiece. The notching device including a first die and a second die that is fixed relative to the first die; and a shiftable punch having opposing first and second cutting surfaces. The punch shiftable between a first punching position and a second punching position and aligned such that the first cutting surface and the first die cooperating to form a first notch when the punch proceeds towards the first position, and the second cutting surface and the second die cooperating to form a second notch when the punch proceeds towards a second position.

Description:
TECHNICAL FIELD 
   The technology generally relates to notching equipment, and more specifically to a device that is capable of consecutively forming notches in a hollow workpiece. 
   BACKGROUND 
   Polyvinyl tubing is commonly used for a variety of products such as fencing, decking and lawn furniture. In these and other similar applications it is often required to process the tubing through multiple manufacturing steps to produce a single complete part. For example, in many applications notches must be formed into two or more of the tube sidewalls in order to permit an end portion of one piece of tubing to be inserted and locked within a cooperating aperture of another piece. In one exemplary application, the notched end of one tubular polyvinyl fence rail is inserted into a receiving aperture in a tubular polyvinyl fence post, thereby forming an easy to assemble joint. 
   The processing of such components often requires the polyvinyl tubing to go through several repetitions in a single position notching die to create a complete section of tubing. In such a process, the workpiece (e.g. a piece of hollow polyvinyl tubing or some other tubing material) is aligned and inserted into the notching die. The die is cycled to create a notch on a first surface, and then the workpiece is removed from the die and reoriented. The reoriented workpiece is again inserted into the die to create another notch on a second surface. This process is repeated until the desired number and location of notches is achieved. 
   In order to improve processing efficiencies, it may be desirable to create multiple notches without having to remove and reorient the workpiece. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is perspective view of a device for notching a hollow workpiece; 
       FIG. 2  is an enlarged side elevational view of the die set of the notching device illustrated in  FIG. 1 , and the workpiece prior to the beginning of the notching cycle; 
       FIG. 2A  is an enlarged side elevational view of another embodiment of the punch of the notching device illustrated in  FIG. 1 ; 
       FIG. 3  is a front elevational view of the notching device illustrated in  FIG. 1  showing the installed workpiece prior to the beginning of the notching cycle; 
       FIG. 4  is a side elevational view of the notching device illustrated in  FIG. 1  with the workpiece installed; 
       FIG. 5  is a side elevational view similar to  FIG. 4  but showing the notching device in the first notching position; 
       FIG. 6  is a side elevational view similar to  FIGS. 4 and 5  but showing the notching device in the second notching position; 
       FIG. 7  is a side elevational view similar to  FIGS. 4 through 6  but showing the completed workpiece being removed from the notching device; 
       FIG. 8  is an enlarged fragmentary perspective view in of a notch formed in a hollow workpiece; and 
       FIG. 9  is an enlarged fragmentary perspective view in of a notched workpiece engaging a hollow member. 
   

   DETAILED DESCRIPTION 
   The following detailed description is not intended to limit the scope of the device to the precise form or forms detailed herein. Instead, the following description is intended to be illustrative of the principles disclosed herein so that others may follow the teachings. 
     FIG. 1  illustrates a notching device generally indicated by the numeral  100 . The notching device  100  includes a pair of two-position die sets  102  and  104 . The first die set  102  includes a punch block  106 , a top die  108 , and a bottom die  110 . The second die set  104  includes a punch block  112 , a top die  114 , and a bottom die  116 . Preferably both the first die set  102  and the second die set  104  are manufactured from a tool steel, such as S-7, A-2, O-6, CPM, or any other applicable series of steel, all of which are commonly employed in the art. Moreover, it will be understood that the notching device disclosed herein is described as having a vertical orientation, only for the sake of convenience, and not because it impacts the operation or effectiveness of the device in any way. The notching device further includes a fixed top support block  118 , a fixed bottom support block  120  and a shiftable support block  122  disposed therebetween. The shiftable support block  122  is fixedly mounted to at least one actuator  124  and to a coupling block  126 . The coupling block  126 , in turn, is fixedly attached to at least one linear bearing slide  128 . 
   The actuator  124  may be a commercially available P ARKER ® hydraulic cylinder or a B IMBA ® pneumatic cylinder, both of which are configured to have three operating positions, top, at-rest (neutral), and bottom, and are sized to generate sufficient force to notch the workpiece. The linear bearing slide  128  may be, for example, a T HK ® SR-85T LM guide or a T HOMSON ® continuously supported single ( 1 CA) RoundRail® linear guide or any other suitable bearing system. Typical linear bearing slides include a ground shaft or contoured rail  130  and at least one slider  132 . The slider  132  is designed to engage the rail  130  with a plurality of roller elements (not shown) such as ball, cylindrical or tapered bearings, to provide smooth continuous motion between two points. The actuator  124  and linear bearing slide  128  cooperate to shift and precisely guide the shiftable support block  122  during punching operations. 
   The top die  108  and bottom die  110  are vertically aligned and fixedly attached to the top support plate  118 , and the bottom support plate  120 , respectively. The punch block  106  is fixedly attached to the shiftable support block  122 , as well as the actuator  124  and the linear bearing slide  128 , and is vertically aligned between the top die  108  and the bottom die  110 . A plurality of fasteners A, or any other suitable attachment means, may be used to fixedly assembled the above-discussed components. Examples of suitable fasteners A may include shoulder bolts, cap head screws, quick release fasteners, and dowel pins. The physical configuration of the top die  108 , the bottom die  110  and the movable punch block  106  therebetween, creates a top and bottom receiving cavity  134  and  136 . The receiving cavities  134  and  136  are defined as the space between the top die  108  and the punch block  106 , and the punch block  106  and the bottom die  110 . 
     FIG. 2  illustrates an enlarged view of the first die set  102  and the surrounding components when the actuator  124  is in the at-rest position. The top die  108  is fixedly attached to the top fixed support block  118  via an adaptor  138  and a fastener A. The top die  108  includes a first cutting surface  140  and a second cutting surface  142 . The second cutting surface  142  may be placed into operation by removing fasteners A from the adaptor  138 , inverting the top die  108  and reattaching the top die  108  to the adaptor  138  via a predrilled hole  144  and the fastener A. The bottom die  110  is fixedly attached to the bottom fixed support block  120  via an adaptor  146  and the fastener A. The bottom die  110  includes a first cutting surface  148  and a second cutting surface  150 . The bottom die  110 , similar to the top die  108 , may be inverted by reorienting the die block and reattaching it using the predrilled hole  144  and the fastener A. 
   A workpiece  152  having an interior  154  is shown positioned within the receiving cavities  134  and  136 . A first end  156  of the workpiece  152  is gauged or positioned against the shiftable support block  122 , as indicated by the numeral  158 . A gap  162  is shown separating the top surface of workpiece  152  and the top die  108 , while the bottom surface of the workpiece  152  is firmly supported by the bottom die  110 . The gap  162  is sized to allow the finished workpiece (as illustrated in  FIG. 8 ) to be removed from the receiving cavities  134  and  136 . 
   The punch block  106  includes a cantilevered punch  164  extending from the main body of the punch block  106  into the interior  154  of the workpiece  152 , thereby positioning the punch  164  between the top die  108  and the bottom die  110 . The punch  164  includes a first punching surface  166  that is angled upwards in the direction of the first die surface  140 . The punch  164  further includes a second opposing punching surface  168  that is angled downwards in the direction of the second die surface  148 . The relative angle of the punching surfaces  166  and  168  effectively magnifies the cutting force experienced by the workpiece  152  by reducing the contact area through which the force is transmitted. The reduced contact area, in effect, focuses the cutting force and allows the punch to “scissor” through the material, thereby increasing the overall efficiency of the notching device  100 . 
     FIG. 2A  illustrates an alternate embodiment of the punch block  106 . A punch block  106 A includes a punch  164 A formed to accept a pair of removable cutting surfaces  166 A and  168 A. The removable cutting surfaces  166 A and  168 A are fixedly attached to the punch  164 A using at least one fastener A. Moreover, the cutting surfaces  166 A and  168 A may be further positioned using a ground dowel pin or a specially formed pocket or step formed within the punch  164 A. By forming the punch  164 A in this manner, which is well known in the art, the precise location of the cutting surfaces  166 A and  168 A can be insured. 
     FIG. 3  illustrates a front view of the notching device  100  of  FIG. 1  showing the workpiece  152  positioned within the receiving cavities  134  and  136 , prior to the beginning of the notching cycle. The notching device  100  further includes a cover  170  designed to limit access to the individual components of the notching device  100 . The cover  170  further provides a safety shield to guard against potential injuries and unwanted and potentially harmful material from entering and fouling the operation of the notching device  100 . 
   As will be readily apparent to a person of ordinary skill in the art, the notching device  100  is generally symmetrical about a centerline CL. Moreover, the two-position die sets  102  and  104  are shown (in  FIGS. 1 and 3 ) as mirror images of each other. For the sake of brevity and clarity, the symmetrical die set  102  has exclusively been described about the centerline CL (see  FIG. 3 ). It will be understood that although the operation of the second two-position die  104  is identical, the physical configuration may or may not be the same as the first two-position die set  102 , depending on the defined manufacturing requirements. 
     FIGS. 4 to 7  illustrate the notching device  100  in discrete positions throughout one of the preferred embodiments of the notching cycle.  FIG. 4  illustrates the notching device  100  in the at-rest position which is defined as the point at which an actuator rod  172  is in the neutral, or non-punching position. The workpiece  152  is inserted into the receiving cavities  134  and  136 , in the direction indicated by the arrow  174 . The first end  156  of the workpiece  152  is gauged by the shiftable support block  122  at the point  158 , thereby properly positioning the workpiece within the notching device  100 . 
     FIG. 5  illustrates the notching device  100  in the top or first punching position. The notching device  100  shifts from the at-rest position (shown in  FIG. 4 ) to the first punching position, in response to the extension of the actuator rod  172  in the direction indicated by the arrow  174 . The actuator rod  172  may be fixedly attached to the shiftable support plate  122  by engaging the threaded end (not shown) of the actuator rod  172  and a complementary aperture formed into the shiftable support plate  122 . The shiftable support plate  122 , attached punching block  106 , and cantilevered punch  164  respectively, are in turn sequentially, vertically guided by the coupling block  126  and linear slide bearing  128 . The extension of the actuator rod  172  forces the punch  164  and the first punching surface  166  into contact with an interior surface  176  of the workpiece  152 . The workpiece  152 , the punch  164 , and the first punching surface  166  shift upward until an external surface  178  of the workpiece  152  engages the first cutting surface  140  of the top die  108 . At this point, the first punching surface  166  passes through a plane defined by the first cutting surface  140 , thereby piercing the workpiece and forming an upper notch  180 . 
     FIG. 6  illustrates the notching device  100  in the bottom or second punching position. The notching device  100  shifts downward from the first punching position (shown in  FIG. 5 ) through the at-rest position (shown in  FIG. 4 ), to the second punching position in response to the retraction of the actuator rod  172  in the direction indicated by the arrow  182 . The retraction of the actuator rod  172 , the attached slidable support plate  122  and punching block  106  forces the punch  164  and the second punching surface  168  into contact with an interior surface  184  of the workpiece  152 . The workpiece  152 , the punch  164 , and the second punching surface  168  shift downward until an external surface  186  of the workpiece  152  engages the first cutting surface  148  of the bottom die  110 . At this point, the second punching surface  168  passes through a plane defined by the first cutting surface  148 , thereby piercing the workpiece and forming a bottom notch  188 . 
     FIG. 7  illustrates the notching device  100  in the at-rest position (similar to  FIG. 4 ) at the completion of a notching cycle. The completed workpiece  152  having the upper notch  180  and the bottom notch  188  is removed from the receiving cavities  134  and  136 , in the direction indicated by the arrow  190 . It should be noted that the bottom notch  188  may be retained within the bottom die  110  thereby requiring the workpiece  152  to be rocked (laterally or vertically) to facilitate removal. The gap  162 , as previously discussed, is sized to allow the finished workpiece to be removed from the receiving cavities  134  and  136 . 
     FIGS. 8 and 9  illustrate a finished workpiece  152  external to the notching device  100 , and an exemplary application of the workpiece  152  in operation.  FIG. 8  illustrates a hollow workpiece  152  having a first end  156  and the upper notch  180  formed proximate to the first end  156 .  FIG. 9  illustrates the finished workpiece  152  engaged, for example, with a complementary fencing piece  192 . The complementary fencing piece  192  includes a receiving aperture  194  sized to accept the first end  156 , the upper notch  180  and the bottom notch  188  of the workpiece  152 . Upon insertion of the first end  156  into the receiving aperture  194 , the upper notch  180  and the lower notch  188  flex to positions contiguous with the external surfaces  178 ,  184  of the workpiece  152 . Once clear of the receiving aperture  194 , the notches  180  and  188  return to their original, notched positions and engage the inner surface  196  of the complementary fencing piece  192  to prevent removal of the workpiece  152 . 
   Those skilled in the art will appreciate that, although the teachings of the invention have been illustrated in connection with certain embodiments, there is no intent to limit the invention to such embodiments. On the contrary, the intention of this application is to cover all modifications and embodiments fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.