Abstract:
A tube-forming device for notching and/or punching a tubular work piece includes a work piece holder to hold the tubular work piece, a tool insertable into an end of the work piece; a tool holder to hold the tool, and a dual action cam assembly to alternately drive the tool in first and second directions to engage the tool with first and second sides of the work piece.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to tools for forming, notching and cutting tubular work piece and, more particularly, to a tube-forming device to perform operations on opposing sides of a tubular work piece without removing the tubular work piece from the tool.  
         BACKGROUND OF THE INVENTION  
         [0002]    Metal tubing is used as a structural component in many consumer products, such as bicycles, furniture, lawn and garden equipment, fencing, and playground equipment. Joining two pieces of tubular stock requires notching the end of a first piece of stock to fit against the curved surface of a second piece of stock. The two pieces can then be joined by welding or brazing.  
           [0003]    Machines for forming notches in tubular stock are known. For example, it is known to use a punch and die to shear a notch in the end of a tubular work piece. A common practice is to enclose the tubular work piece in a die that extends around the outer periphery of the work piece and guide a punch through the work piece with sufficient force to shear away the material necessary to produce the desired shape. Because the wall initially contacted by the punch is not supported internally, the wall of the tube is deformed by this process and requires secondary finishing operations.  
           [0004]    Another common practice involves the use of a die that extends around the outer periphery of the work piece as described above. The punch is inserted in the open end of the work piece. The punch shears away material on one side of the work piece. The work piece is then removed from the machine, rotated 180 degrees, and reinserted to shear the other side of the work piece. This method has several drawbacks. First, it requires two operations to form a notch in both sides of the work piece. Secondly, care must be taken when reinserting the work piece to insure that the notches in the two sides are properly aligned.  
           [0005]    Accordingly, there is a need for a tube notching device that is can form notches in tubular stock in a single operation without requiring secondary operations to prepare the work piece for joining.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is a tube-forming device for notching and/or punching a tubular work piece. The tube-forming device comprises a work piece holder to hold the tubular work piece, a tool insertable into an end of the work piece; a tool holder to hold the tool, and a dual action cam assembly to alternately drive the tool in first and second directions to engage the tool with first and second sides of the work piece.  
           [0007]    The work piece holder may comprise a fixed die block having an opening therein to accommodate one or more interchangeable dies. The dies are in the form of a sleeve that surrounds the work piece outer circumference of the work piece. A cutting edge is formed at one end of the sleeve that cooperates with the tool to shear material from the work piece.  
           [0008]    The tool may, for example, comprise a shear or punch that is shaped to form a notch or other shape in the end of the work piece. The tool may also comprise piercing tool to form openings in the work piece.  
           [0009]    The tool holder may comprise a carrier block that slides in a channel in the die block. The carrier block may include an opening therein to removably receive one or more interchangeable tools. The carrier block may further include an opening for the dual action cam assembly that produces a reciprocating motion. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a perspective view of the tube forming device of the present invention.  
         [0011]    [0011]FIG. 2 is an exploded perspective view of a die block used in the tube forming device.  
         [0012]    [0012]FIG. 3 is an exploded perspective view of a carrier block used in the tube notching apparatus to carry a tool.  
         [0013]    [0013]FIG. 4 is a perspective view of a die that inserts into the die block.  
         [0014]    [0014]FIG. 5 is a perspective view of a tool that cooperates with the die to shear the work piece.  
         [0015]    [0015]FIG. 6 is a longitudinal cross-section of the tool assembly.  
         [0016]    [0016]FIG. 7 is a transverse cross-section of the tool assembly.  
         [0017]    [0017]FIG. 8 is an exploded cross-section of the tool assembly.  
         [0018]    [0018]FIGS. 9A through 9D are schematic illustrations showing the operation of the dual action cam assembly. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    Referring now to the drawings, the tube-forming device of the present invention is shown therein and indicated generally by the numeral  10 . The tube-forming device  10  comprises a housing  12  and a tool assembly  14 . The tool assembly  14 , which is shown in more detail in FIGS.  2 - 9 , includes a die block assembly  16  and a carrier block assembly  18 . The die block assembly  16  accepts interchangeable dies  60  that receive tubular work pieces of varying sizes. The carrier block assembly  18  accepts a tool  90 , such as a shear or punch, that is used to notch or perforate the tubular work piece. A dual action cam assembly  100  causes the carrier block assembly  18  to linearly reciprocate. As will be described hereinafter in greater detail, a tubular work piece slides into the die  60  and is notched or perforated on two opposing sides by the tool  90  as it reciprocates back and forth.  
         [0020]    [0020]FIG. 2 is an exploded perspective view of the die block assembly  16 , which functions as a work piece holder. The die block assembly  16  includes a die block  30  and one or more interchangeable dies  60 . The die block  30  includes a top plate  32 , bottom plate  34 , and end plates  36  and  38 . Die block  30  includes an opening  50  to receive one or the interchangeable dies  60 , shown in FIG. 4. Clearance areas  52  are formed on the inner surface of the die block  30  on either side of the opening  50 . Clearance areas  52  provide clearance for the material that is removed from the tubular work piece. The removed material falls through openings  46  in the bottom plate  34 . The top plate  32  includes a down-turned lip  40 . The bottom plate  34  includes an up-turned lip  42 . The die block  30 , top plate  32 , and bottom plate  34  form a channel  44  when assembled together (see FIG. 6). The ends of the channel  44  are closed off by end blocks  36  and  38 .  
         [0021]    [0021]FIG. 4 is a perspective view of an exemplary die  60  that fits into the opening  50  of the die block  30 . The die  60  comprises a generally cylindrical sleeve  64  having a flange  62  at one end thereof. In the embodiment shown in FIG. 4, the end of the sleeve  64  opposite the flange  62  includes a notch  66 . The flange  62  includes a series of holes  68  that accept bolts for attaching the die  60  to the die block  30 . The inner diameter of the die  60  is sized to receive a tubular work piece of a predefined outside diameter. Typically, the tube-forming device  10  would include a plurality of dies  60  adapted to receive tubular work pieces of different sizes and adapted to form notches of a plurality of different shapes and sizes.  
         [0022]    The carrier block assembly  18  is slideably mounted in the channel  44  in the die block assembly  16  so as to be movable relative to the die block assembly  16 . The carrier block assembly  18  comprises a carrier block  70  and tool  90 . Carrier block  70  includes a cylindrical opening  72  and generally rectangular recess  74 , which are adapted to receive the tool  90 , as will be hereinafter described. Carrier block  70  further includes a pair of cam openings  76  and  78 . Cam openings  76  and  78  are rectangular in form and are formed in opposing sides of the carrier block  70 . Cam opening  76  is formed in the front side of the carrier block  70 , while cam opening  78  is formed in the back side of the carrier block  70 . Cam openings  76  and  78  are offset with respect to one another as shown in FIG. 3.  
         [0023]    The tool  90 , shown in FIG. 5, comprises a base  92 , intermediate portion  94 , and a head portion  96 . The intermediate portion  94  of the tool  90  is received in the cylindrical opening  72  in the carrier block  70 , while the base  92  is received in the recess  74 . The head portion  96  of the tool  90  projects from the front of the carrier block  70 . In the disclosed embodiment, the head portion  96  of the tool  90  functions as a shearing member to shear material from the tubular work piece. More particularly, the head portion  96  is shaped to notch the tubular work piece. The head portion  98  could have a variety of shapes to form notches of different shapes (e.g., v-shaped). Also, the head portion  96  could comprise a punch designed to form perforations of various shapes in the work piece.  
         [0024]    Tool  90  is designed to be easily removed from the carrier block  70 . A series of openings  98  are formed in the base  92  of the tool  90 . Openings  98  align with corresponding openings  88  in the carrier block  70 . Bolts  86  secure the tool  90  to the carrier block  70 .  
         [0025]    [0025]FIG. 7 illustrates the tool assembly  14  in cross-section assembled with the die  60  and tool  90  inserted. Note that the shape of the notch  66  in the die  60  matches the configuration of the head portion  96  of the tool  90  so that the two parts function as a shear. An exploded cross-section of the tool assembly  14  is shown in FIG. 8.  
         [0026]    In a normal or neutral position, the carrier block  70  is positioned such that the tool  90  is centered with respect to the die  60 . Springs  80  may be used to bias the carrier block  70  to the neutral position. While the carrier block  70  is in the neutral position, a work piece may be inserted into the die  60  over the head portion  96  of the tool  90  until the work piece engages the land surrounding the head portion  96 . As the carrier block  70  moves in either direction from the neutral position, the tool  90  shears off material from the work piece as shown in FIG. 6.  
         [0027]    A dual action cam assembly  100  reciprocates the carrier block  70  relative to the die block assembly  16 . The dual action cam assembly  100  comprises a first cam  102 , a second cam  104 , a cam shaft  106 , and a motor  108 . Cam  102  is disposed in cam opening  76  and cam  104  is disposed in cam opening  78 . The main lobes of the cams  102  and  104  are disposed at an angle of approximately 90° with respect to one another. Cams  102  and  104  are mounted on a cam shaft  106  and rotate as a single unit. The cams  102  and  104  push against the walls of the opening  76  and  78 , respectively, causing the carrier block  70  to reciprocate linearly in channel  44  when the cams  102  and  104  are rotated. While the dual action cam assembly in the disclosed embodiment comprises two separate cams  102  and  104 , a single cam with multiple lobes could be designed for equivalent operation.  
         [0028]    FIGS.  9 A- 9 D illustrate the operation of the cams  102  and  104 . In FIG. 9A, the carrier block  70  is in a neutral position. In this position, the tool  90  is aligned with the axis of the die  60 . The cams  102  and  104  rotate clockwise to the position shown in FIG. 9B to begin a first phase of the tool cycle. As the cams  102  and  104  rotate from the position shown in FIG. 9A to the position shown in FIG. 9B, cam  102  pushes against the front wall  76 A of cam opening  76 . The action of the cam  102  pressing against front wall  76 A pushes the carrier block  70  to the left (as seen in FIG. 9B). As the carrier block  70  moves to the left, the tool  90  shears material on one side of the work piece. As the dual action cam assembly  100  continues rotating, cam  102  begins pushing on the rear wall  76 B of cam opening  76 , causing the carrier block  70  to begin moving in a rearward direction. This is the start of a second phase of the tool cycle. When the cam assembly  100  reaches the position shown in FIG. 9C, the carrier block  70  will be in the rear-most position. As the carrier block  70  moves from the position shown in FIG. 9B to the position shown in FIG. 9C, the tool  90  shears off material on the rear side of the work piece. As the cam assembly  100  rotates from the position shown in FIG. 9C to the position shown in FIG. 9D, cam  104  pushes against the front wall  78 A of the cam opening  78  to push the carrier block  70  back to the neutral position. This is the third phase, referred to as the idle phase, of the tool cycle. During the idle phase a new work piece may be inserted.  
         [0029]    The tube-forming device  10  of the present invention is a simple, yet highly, efficient machine for notching or perforating a tubular work piece. Unlike prior art to notching devices, the tube-forming device  10  of the present invention does not require the operator to remove and reinsert the work piece in order to notch both sides of the work piece. Using the tubeforming device  10  of the present invention, the work piece is simply inserted into the die  60  and both sides are notched or punched without any further action taken on the part of the operator. The operator simply inserts and removes the work pieces in synchronism with the action of the carrier block  70 . Using the present invention, a single operator could process up to 3600 work pieces per hour.  
         [0030]    The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.