Abstract:
A vertical compression bending machine that uses linear bearings to guide the ram and cushions assemblies. The inventive machine also employs an adjustment mechanism to align the wing dies relative to one another.

Description:
BACKGROUND 
     1. Field of Invention 
     The present invention relates to a machine that bends tubing. The machine employs linear ball bearings to reduce friction in the system. 
     2. Description of Art 
     Manufacturers of industrial equipment have been building tube bending machines to bend tubing for decades. One such machine is a vertical compression bending machine. A vertical compression bender makes use of a ram die and two wing dies. During the bending process, the ram die, along with a supporting ram assembly, advances in a linear fashion toward the two wing dies. A tube, supported by the two wing dies, is initially contacted by the ram die during the advancement of the ram assembly. After the ram die makes initial contact with the tube, it continues to push through the tube while forcing the wing dies to rotate away and outward from the ram die. The ram die sees resistance from the tube along with the resistance from the wing dies. In order for the tube to stay up and inside the ram die during the bending process, the wing dies must provide a counter force (cushion) in a direction against the advancing ram die. The counter force from the wing dies will hold the tube in a firm position against the ram die. The ram die continues to advance while at the same time overcoming the resistance of the tube and wing dies. The ram die continues to advance until the tube reaches the required bend angle. At that point, the ram assembly reverses direction and returns to its home position. The wing dies also reverse direction and both wing dies rotate back to their home position. 
     Over the years manufacturers have relied on various types of wear pads to guide the ram assembly during the bending process. A typical wear pad is constructed from bronze and acts as a bearing surface guiding the ram die and thus the ram assembly during a bending stroke. Wear pads were designed into this application decades ago because they afforded the best load bearing capability at a reasonable cost. 
     A compression bender is depicted in U.S. Pat. No. 2,997,141 issued to Bower et al. The Bower et al. patent shows a bender that uses guide members  25  and  26  along with wing slides  29  and  30  to ensure that the ram die  36  is guided along a linear path during a bending operation. The guide members  25  and  26  act as wear plates. These wear plates, most often constructed from a bronze material, are the bearing surfaces that allow the ram die to lynamically thrust to and from the wing dies while at the same time providing a bearing surface guide the ram assembly along a linear path. 
     The Bower et al. patent also uses the same approach when guiding the motion of the piston rods  87  and  96 . Bower et al. relies on the bushings inside the cushion cylinders  77  and  78  to help support the forces on the piston rods  87  and  96 . Cylinders  77  and  78  provide a counter force (cushion) to the advancing ram die  36 . This counter force is transmitted to the ram die  36  through the wing dies  59  and  66  and the tube. 
     One disadvantage of the Bower et al. patent is the friction associated with the wear plates that guide the ram assembly. These bearing surfaces often require constant maintenance and eventually will need to be replaced due to the friction associated with the wear plates. 
     Another disadvantage of the Bower et al. patent is the side loads on the piston rods  87  and  96 . These side loads will in time require unnecessary maintenance and thus the bushings in the cylinders  77  and  78  will have to be replaced. In general, these bushings should never take side loading. 
     SUMMARY OF THE INVENTION 
     Accordingly, several objects and advantages of my invention are: 
     (a) to reduce the friction associated with the ram assembly during a bending operation; 
     (b) to reduce the cost of maintenance associated the ram and cushion assemblies; 
     (c) to reduce the friction of the bearing assembly used to guide the cushion assembly; and 
     (d) to prevent a side load from imparting on the cushion cylinder&#39;s piston rod. 
     Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
     The foregoing objects and advantages can be achieved by providing a vertical compression bending machine comprising a first wind die which supports a second part of the tube, a frame supporting a first linear rail, a first linear bearing which slidably moves along the first linear rail, a ram block mounted to the first linear bearing, and a ram die, mounted to the ram block, which vertically moves to form a bend in the tube, wherein the ram block and first linear bearing move in conjunction with the ram die so that the first linear bearing slides along the first linear rail, and the first and second wing dies provide movable support to the tube as the ram die bends the tube. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an isometric view of the first embodiment depicting the linear rail and linear bearing supporting the ram assembly; 
     FIG. 2 shows an isometric view of the first embodiment depicting a tube being bent; 
     FIG. 3 shows an isometric view of the wing die assemblies, the cushion assembly, a linear rail supporting the cushion assembly, and a mechanism to adjust the wing dies relative to one another. 
     FIG. 4 shows an isometric view of the first linear rail and its internal lubrication passage. 
     FIG. 5 shows an isometric view of the second linear rail and its internal lubrication passage. 
     FIG. 6 shows the mechanism to adjust the position of the wing dies. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With initial reference to FIG. 1, the first embodiment  10  is shown. A ram die  11  is mechanically fastened to a ram block  12 . Ram block  12  is mechanically fastened to a linear bearing  13 . Linear bearing  13  may be of the type described by Teramachi in U.S. Pat. No. 4,040,679 and by Teramachi in U.S. Pat. No. 4,252,709. 
     In both U.S. Pat. No. 4,040,679 and U.S. Pat. No. 4,252,709, Teramachi teaches about a linear bearing that employs recirculating ball bearings. The ball bearings recirculate in a track while the bearing block advances in a linear fashion along a linear rail. The grooves in the linear rail help captivate the ball bearings as the ball bearings recirculate within the bearing block. This technique results in rolling friction as the linear bearing moves relative to the linear rail. 
     Linear bearing  13  is coupled to a linear rail  14 . A lube passage  63  is formed into linear rail  14 , see FIG.  4 . 
     Linear rail  14  is fastened to frame  15 . Ram block  12  is fastened to a coupling  17 . Coupling  17  is fastened to a piston rod  18  and piston rod  18  is joined to a ram cylinder  19 . Ram cylinder  19  is fastened to frame  15 . 
     A wing die  20  is supported by a wear strip  22 , a wear strip  24 , and a wear strip  26 . Wear strips  22 ,  24 , and  26  are supported by a support housing  55 . Support housing  55  is fastened to a support block  28 . Support block  28  is fastened to a cushion shaft  30 . Wear strips  22 ,  24 , and  26 , support housing  55 , and cushion shaft  30  are considered the first cushion shaft assembly  65 . 
     A wing die  21  is supported by a wear strip  23 , a wear strip  25 , and a wear strip  27 , see also FIG.  3 . Wear strips  23 ,  25 , and  27  are supported by a support housing  56 . Support housing  56  is fastened to a support block  29 . Support block  29  is fastened to a cushion shaft  31 , see also FIG.  3 . Wear strips  23 ,  25 , and  27 , support housing  56 , and cushion shaft  31  are considered the second cushion shaft assembly  66 . 
     Cushion shaft  30  is supported by a bearing block  32  and a bearing block  34 . Bearing blocks  32  and  34  are fastened to frame  15 . 
     Cushion shaft  31  is supported by a bearing block  33  and a bearing block  35 , see also FIG.  2 . Bearing blocks  33  and  35  are fastened to frame  15 . 
     From FIG. 2, located in wing dies  20  and  21  is a tube  57 . 
     From FIG. 1, an encoder bracket  58  is fastened to bearing block  35 . Fastened to encoder bracket  58  is an encoder  59 . Encoder  59  is coupled to cushion shaft  31 . 
     From FIGS. 3 and 6, a rocker arm  36  and a rocker arm  37  are fastened to cushion shafts  30  and  31  respectively. A rocker bearing  60  is supported by a pin  43 . Pin  43  is fastened to rocker arm  36 . A rocker bearing  61  is supported by a pin  44 . Pin  44  is fastened to rocker arm  37 . 
     Rocker arm  36 , rocker bearing  38 , and pin  43  are considered the rocker arm assembly  68 . Rocker arm  37 , rocker bearing  39 , and pin  44  are considered the rocker arm assembly  69 . 
     From FIG. 6, rocker bearings  60  and  61  roll inside a tilt block  40  on surface  40   a  and  40   b , respectively. A cap block  41 , fastened to tilt block  40 , captivates rocker bearings  60  and  61  against tilt block  40 , see FIG. 6. A pin  45  supports tilt block  40 . Pin  45  is fastened to housing  42 . A bolt  70  and a bolt  71  are threaded into housing  42  and both bolts  70  and  71  butt up against tilt block  40 . Housing  42  is fastened to a piston rod  49 . Piston rod  49  is connected to a cushion cylinder  50 . Cushion cylinder  50  is fastened to frame  15 . Housing  42  is fastened to a linear bearing  47 . Linear bearing  47  is coupled to a linear rail  48 . Linear rail  48  is fastened to frame  15 . 
     Linear bearing  47  may be of the type described by Teramachi in U.S. Pat. No. 4,040,679 and by Teramachi in U.S. Pat. No. 4,252,709. 
     In both U.S. Pat. No. 4,040,679 and U.S. Pat. No. 4,252,709, Teramachi teaches about a linear bearing that employs recirculating ball bearings. The ball bearings recirculate in a track while the bearing block advances in a linear fashion along a linear rail. The grooves in the linear rail help captivate the ball bearings as the ball bearings recirculate within the bearing block. This technique results in rolling friction as the linear bearing moves relative to the linear rail. 
     Linear bearing  47  is coupled to linear rail  48 . Linear rail  48  is of the type described by Teramachi in U.S. Pat. Nos. 4,040,679 and 4,253,709. A lube passage  64  (see FIG. 5) is formed into linear rail  48 . 
     Tilt block  40 , cap block  41 , pin  45 , bolt  70 , bolt  71 , and housing  42  make up the cushion assembly  67 . 
     In operation, pressure is applied to one side of cylinder  19  causing piston rod  18 , initially extended in its home position, to retract toward cylinder  19 . The retraction of piston rod  18  causes coupling  17 , ram block  12 , ram die  11 , and linear bearing  13  to advance toward cylinder  19 . 
     Prior to ram die  11  making initial contact with tube  57 , sufficient pressure is present in cushion cylinder  50  to cause piston rod  49  to be fully extended in the home position. At this point, wing dies  20  and  21  are adjacent to one another at a right angle as shown in FIG.  1 . 
     From FIG. 2, the ram die  11  continues to advance toward ram cylinder  19  and thus starts to bend tube  57 . As the bending process continues, a pressure is maintained in cushion cylinder  50 . This pressure creates a counter force (cushion) against the advancing ram die  11 . 
     The counter force is realized by ram die  11  when wing dies  20  and  21  are forced to rotate about cushion shafts assemblies  65  and  66 . The pressure in cushion cylinder  50  tends to prevent cushion shaft assemblies  65  and  66  from rotating. With a pressure in cushion cylinder  50 , piston rod  49  tends to force cushion assembly  67  away from cushion cylinder  50 . This causes rocker arm assemblies  68  and  69  to keep a counter torque on cushion shaft assemblies  65  and  66 . This counter torque is in opposition to the advancing ram die  11 . As ram die  11  advances, it not only bends tube  57 , but it also forces piston rod  49  to retract into cushion cylinder  50 . Linear bearing  47  and linear rail  48  support cushion assembly  67  and piston rod  49  as piston rod  49  travels in a direction parallel to linear rail  48 . Any side loading caused by rocker arm assemblies  68  and  69  on cushion assembly  67  will be carried by linear bearing  47  and linear rail  48 . 
     When encoder  59  realizes the preset bend angle, the pressure in ram cylinder  19  causes ram die  11  to return to its home position. This in turn causes cushion cylinder  50  to extend piston rod  49  and thus returns both wing dies  20  and  21  to their home position. 
     During the initial setup of the machine, it may be necessary to adjust the relative position of wing die  20  with respect to wing die  21 . When in the correct home position, both wing dies  20  and  21  should be adjacent and at a right angle to one another in the home position. Therefore, both die  20  and die  21  should be inline to one another when cylinder  19  is in the extended position. Wing dies  20  and  21  can be adjusted to ensure that both wing dies  20  and  21  are inline to one another (coplanar). By adjusting bolts  70  and  71 , the angle between housing  42  and tilt plate  40  will change. Adjusting bolts  70  and  71  will rotate tilt plate  40  about pin  45 . By advancing bolt  70  and retracting bolt  71 , wing die  20  will rotate up and away from ram cylinder  19 . At the same time, wing die  21  will rotate down and toward ram cylinder  19 . By retracting bolt  70  and advancing bolt  71  toward tilt plate  40 , wing die  20  will rotate down and toward cylinder  19  and wing die  21  will rotate up and away from cylinder  19 . This adjustment feature provides for ease of assembly to ensure that both wing dies are inline (parallel and coplanar) to one another in the home position. When wing die  20  and wing die  21  are inline, the relative angle formed between both dies  20  and  21  is zero. The relative angle is measured in the plane at which tube  57  is being bent. 
     During operation of the inventive machine, lubrication can be supplied to the rolling elements located inside linear bearings  13  and  47  through lube passage  63  and  64 , respectively. As lubrication is supplied to lube passages  63  and  64 , the rolling elements inside linear bearings  13  and  47  respectively will come in contact with the lubricant being transported through lube passages  63  and  64 . 
     Linear bearings  13  and  47  make use of ball bearings as a rolling element. It should be noted that the ball bearings could be replaced with roller bearings or needle bearings. Both the roller bearings and needle bearings would take the form of a right circular cylinder. This approach would improve the load bearing capability of the linear bearing. 
     Cylinders  19  and  50  operate on hydraulic pressure. However, any number of mechanical power devices could replace one or both of cylinders  19  and  50 . For example, an all electric actuator could replace either cylinder  19  and/or cylinder  50 . 
     Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.