Abstract:
A forming press apparatus with which forming of a plurality of different workpieces can be carried out using a single press. The press has raise/lowerable upper and lower die sets. A plurality of forming die pairs corresponding to a plurality of forming steps to be carried out on a pre-drawn workpiece are mounted en bloc to the die sets. The forming die pairs are disposed in a row on the die sets in the order of the forming steps.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a forming press apparatus for bending a trimmed workpiece. 
     2. Description of the Related Art 
     FIG. 7 hereof shows a typical vehicle body panel forming line of related art. This forming line is made up of three specialized machines: a drawing machine  100 , a trimming machine  103  and a bending machine  106 . 
     The drawing machine  100  has a drawing die pair  102  fitted to a press  101 . The drawing die pair  102  consists of an upper die  102   a  and a lower die  102   b . The trimming machine  103  has a trimming die pair  105  fitted to a press  104 . The trimming die pair  105  consists of an upper die  105   a  and a lower die  105   b . The bending machine  106  has a bending die pair  108  fitted to a press  107 . The bending die pair  108  consists of an upper die  108   a  and a lower die  108   b.    
     An example of forming a vehicle body panel with these specialized machines  100 ,  103  and  106  will now be described. 
     First, a blank is set in the drawing die pair  102  of the drawing machine  100 . Then, the press  101  is operated and the blank is drawn. By this means, a drawn forming  110  is obtained. 
     Next, the drawn forming  110  is set in the trimming die pair  105  of the trimming machine  103 . The press  104  is then operated and the edge  110   a  of the drawn forming  110  is trimmed off. By this means, a trimmed forming  111  is obtained. 
     The trimmed forming  111  is then set in the bending die pair  108  of the bending machine  106 . The press  107  is then operated and bending is carried out on the edge  111   a  of the trimmed forming  111 . By this means, a bent forming  112  is obtained. 
     Finally, various holes are made in the bent forming  112  to produce a vehicle body panel, and the vehicle body panel is assembled to a vehicle body on an assembly line. 
     In this way, a method has been typically employed wherein to manufacture a vehicle body panel at low cost wherein the vehicle body panel is mass-produced using three separate specialized machines like the drawing machine  100 , the trimming machine  103  and the bending machine  106 . 
     However, in recent years there has been a trend for car model changes to be made in relatively short cycles, and there has also been a change from the mass production of a few product types to the smaller-volume production of each of numerous product types. In the case of this high-variety, small-volume production, if three specialized machines like the drawing machine  100 , the trimming machine  103  and the bending machine  106  are provided separately in a vehicle body panel forming line, the cost of the plant cannot be recovered and it is difficult for the cost of the vehicle body panel to be kept down. 
     In this connection, in U.S. Pat. No. 4,625,540 there is disclosed a press apparatus wherein a plurality of forming die pairs corresponding to a plurality of forming steps are mounted to a single press, and drawing is carried out at a first working station, piercing and finishing are carried out at a second working station, and trimming and splitting are carried out at a third working station. 
     However, when an upper/lower pair of dies for drawing are mounted in a row with other dies in the same press, because of the need to lay out cushion pins and the like for carrying out drawing from a flat sheet workpiece, inevitably the press itself becomes large. 
     And also, when a flat sheet workpiece is to be formed into a three-dimensional shape, because the forming load of the drawing step of the first working station is larger than the forming loads of the second and third working stations, the second and third working stations exert locally high loads. Consequently, the press as a whole becomes load-imbalanced, and the overall balance of the press may not be optimal for carrying out pressing in one shot. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a forming press apparatus with which product cost can be kept down; which is not overly large; and which as a whole does not become load-imbalanced during pressing. 
     To achieve this and other objects, the invention provides a press apparatus for manufacturing a forming by press-forming a workpiece in a plurality of successive forming steps, which comprises a single press and die sets mounted raise/lowerably to the press and carrying en bloc a plurality of forming die pairs corresponding to the plurality of forming steps, wherein the plurality of forming die pairs include a primary forming die pair and a secondary forming die pair so that the plurality of forming steps are carried out simultaneously. 
     A primary forming is carried out on a metal sheet workpiece with the primary forming die pair in one shot of the press, and then the workpiece is transferred to the secondary forming die pair and a primary forming and a secondary forming are carried out simultaneously in the next shot. 
     Preferably, the plurality of forming die pairs are disposed in a row on the die sets in the order of the forming steps. 
     Thus, in this invention, because a plurality of forming die pairs of differing types are provided en bloc on upper and lower die sets on a single press, only one press is required for the plurality of forming steps; a plurality of die pairs can be moved simultaneously; and forming of a plurality of different workpieces can be carried out at the same time. In particular, because the forming of workpieces is carried out after drawing, which involves a large forming load, even when simultaneous forming is carried out with a single press there is no load-imbalance, and a well-balanced load can be applied to the plurality of die pairs. 
     The plurality of die pairs may preferably include a trimming die pair for trimming a pre-drawn forming, a coarse bending die pair for carrying out coarse bending on the trimmed forming obtained, and a finish bending die pair for carrying out finish bending on the coarsely bent forming obtained. 
     The stroke necessary for a trimming die and the stroke necessary for a bending die sometimes differ. Because normally the stroke of a bending die is larger than that of a trimming die, when a trimming die and a bending die are mounted on a single press, sometimes the stroke necessary for the bending cannot be provided and the required bent forming cannot be obtained; in this invention, however, two die pairs, a coarse bending die pair and a finish bending die pair, are provided as the bending die pair. Consequently, coarse bending can be carried out on the trimmed forming with the coarse bending die pair, and finish bending can be carried out with the finish bending die pair on the coarsely bent forming obtained. As a result, the workpiece can be bent in two stages and the workpiece can be bent to the desired shape. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A presently preferred embodiment of the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is an exploded view of a forming press apparatus according to the invention; 
     FIG. 2 is an enlarged sectional view showing a plurality of forming die pairs fitted to upper and lower die sets shown in FIG. 1; 
     FIG. 3 is a side view of the forming press apparatus, showing the plurality of forming die pairs mounted by way of the die sets to a single press; 
     FIG. 4 is a sectional view, corresponding to FIG. 2, showing the upper die set lowered; 
     FIG. 5 is a side view of the forming press apparatus, corresponding to FIG. 3, showing the upper die set raised; 
     FIG. 6 is a view illustrating how workpieces are press-formed and then transferred to the die pair of the next step; and 
     FIG. 7 is a schematic view of a vehicle body panel forming line of related art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description is merely exemplary in nature and is in no way intended to limit the invention, its application or uses. 
     In FIG. 1, a forming press apparatus  10  is made up of a primary forming die pair (trimming die pair)  12  for trimming a drawn forming; a secondary forming die pair (coarse bending die pair)  25  for coarsely bending a workpiece (trimmed forming) thus obtained; a finish bending die pair  40  for finish-bending a workpiece (coarsely bent forming) thus obtained; upper and lower die sets  65 ,  67  for carrying these die pairs  12 ,  25  and  40 ; and a single press  70 , to which the upper and lower die sets  65 ,  67  are mounted and which moves the upper die set  65  toward the lower die set  67 . 
     The trimming die pair  12 , the coarse bending die pair  25  and the finish bending die pair  40  will now be described in detail with reference to FIG.  2 . 
     An upper die  13  of the trimming die pair  12 , an upper die  26  of the coarse bending die pair  25  and an upper die  41  of the finish bending die pair  40  are mounted en bloc to the upper die set  65 . 
     A lower die  20  of the trimming die pair  12 , a lower die  32  of the coarse bending die pair  25 , a lower die  47  of the finish bending die pair  40 , a finish bender  50  and a piercer  55  are mounted en bloc to the lower die set  67 . 
     The press  70  has a base  71 . The base  71  has a pair of columns  72 ,  72  mounted at its sides. The columns  72 ,  72  have guides  73 ,  73 . A slider  74  is fitted between the guides  73 ,  73  so that it can be raised and lowered. Raising and lowering means  75  for raising and lowering the slider  74  is mounted on a bridge part  76 . 
     The raising and lowering means  75  consists of pair of cylinders  77 ,  77  mounted on the bridge part  76 . Rods  77   a ,  77   a  of the cylinders  77 ,  77  are connected to the slider  74 . 
     FIG. 2 shows the trimming die pair  12 , the coarse bending die pair  25  and the finish bending die pair  40  shown in FIG. 1 mounted to the upper and lower die sets  65 ,  67 . 
     The trimming die pair  12  trims a drawn forming  23  set between the upper die  13  and the lower die  20 , by the upper die  13  being lowered to the lower die  20 . 
     The upper die  13  is made up of a holder  14  attached to the upper die set  65 , a pressing pad  15  attached movably up and down to the holder  14 , a plurality of pressing springs  16 ,  16  provided between the pressing pad  15  and the holder  14 , and a cutter  17  disposed outward of the pressing pad  15 . 
     The pressing pad  15  has around the periphery of its lower face a pressing face  15   a  for pressing the periphery of the drawn forming  23 . 
     The pressing springs  16  press the pressing pad  15  against the drawn forming  23  while trimming of the edge  23   a  of the drawn forming  23  is carried out. The lower die  20  is attached to the lower die set  67 ; the drawn forming  23  is set on the lower die  20 , and the lower die  20  trims the drawn forming  23  in cooperation with the upper die  13 . 
     The coarse bending die pair  25  carries out coarse bending on a trimmed forming  35  set between the upper die  26  and the lower die  32 , by the upper die  26  being lowered to the lower die  32 . 
     The upper die  26  is made up of a holder  27  attached to the upper die set  65 , a pressing pad  28  attached movably up and down to the holder  27 , a plurality of pressing springs  29 ,  29  provided between the pressing pad  28  and the holder  27 , and a coarse bend pressing die  30  disposed outward of the pressing pad  28 . 
     The pressing pad  28  has around the periphery of its lower face a pressing face  28   a  for pressing on the periphery of the trimmed forming  35 . 
     The pressing springs  29  press the pressing pad  28  against the trimmed forming  35  while coarse bending is being carried out on the trimmed forming  35 . 
     The coarse bend pressing die  30  has at a left side lower face a sloping bend pressing surface  30   a  and has at a right side lower face a right angle bend pressing surface  30   b.    
     The lower die  32  is attached to the lower die set  67 ; the trimmed forming  35  is set on the lower die  32 , and the lower die  32  carries out coarse bending on the trimmed forming  35  in cooperation with the upper die  26 . 
     The finish bending die pair  40  carries out finish bending with the finish bender  50  and hole-making with the piercer  55  on a coarsely bent forming  49  set between the upper die  41  and the lower die  47 , by the upper die  41  being lowered to the lower die  47 . 
     The upper die  41  is made up of a holder  42  attached to the upper die set  65 , a pressing pad  43  attached movably up and down to the holder  42 , a plurality of springs  44 ,  44  provided between the pressing pad  43  and the holder  42 , and a finish bend pressing die  45  disposed on outward of the pressing pad  43 . 
     The pressing  43  has around the periphery of its lower face a pressing face  43   a  for pressing on the periphery of the coarsely bent forming  49 . 
     The springs  44  press the pressing pad  43  against the coarsely bent forming  49  while finish bending and piercing are being carried out on the coarsely bent forming  49 . 
     The finish bend pressing die  45  has at a left side lower face a first pressing surface  45   a  for actuating the finish bender  50 , and has at a right side lower face a second pressing surface  45   b  for actuating the piercer  55 . 
     The lower die  47  is attached to the lower die set  67 , and the coarsely bent forming  49  is set on the lower die  47 . This lower die  47  has a finish bending surface  47   a  for bending over a sloping bend face  49   a  of the coarsely bent forming  49  and has a piercing surface  47   b  for making holes in a right angle bend face  49   b  of the coarsely bent forming  49 . 
     The finish bender  50  is made up of a guide  51  disposed on the left side of the lower die  47 , a moving member  52  movable on the guide  51 , and a finish bending blade  53  attached to an inner end of the moving member  52 . 
     The piercer  55  is made up of a guide  56  disposed on the right side of the lower die  47 , a moving member  57  movable on the guide  56 , and a hole-making punch  58  attached to an inner side end of the moving member  57 . 
     FIG. 3 shows the forming press apparatus  10  with the plurality of die pairs consisting of the trimming die pair  12 , the coarse bending die pair  25  and the finish bending die pair  40  mounted en bloc on the upper and lower die sets  65 ,  67  and the upper and lower die sets  65 ,  67  mounted to the press  70 . 
     In the press  10  of this preferred embodiment, first the drawn forming  23  is trimmed with the trimming die pair  12  in one shot of the press  70  and then the resulting trimmed forming  35  is transferred to the coarse bending die pair  25  and coarsely bent in the next shot; after that, the resulting coarsely bent forming  49  is transferred to the finish bending die pair  40  and finish bent in a further shot. In this way, a plurality of forming steps can be carried out with a single press  70 . That is, the plurality of steps that are the trimming effected by the trimming die pair  12 , the coarse bending effected by the coarse bending die pair  25  and the finish bending effected by the finish bending die pair  40  can be executed simultaneously. 
     The trimming die pair  12 , the coarse bending die pair  25  and the finish bending die pair  40  are provided en bloc on a single press  70  by way of upper and lower die sets  65 ,  67 . Consequently, only one press  70  is needed, and plant costs can be kept down. As a result, the cost of the product can be lowered. 
     Also, because the trimming die pair  12 , the coarse bending die pair  25  and the finish bending die pair  40  can be controlled simultaneously just by controlling the single press  70 , control can be made simple. 
     The operation of this forming press apparatus  10  will now be explained, on the basis of FIG.  2  through FIG.  5 . 
     As explained above with reference to FIG. 3, as a result of a plurality of shots of the press  70  being made, a drawn forming  23  is set on the lower die  20  of the trimming die pair  12 , a trimmed forming  35  is set on the lower die  32  of the coarse bending die pair  25 , and a coarsely bent forming  49  is set on the lower die  47  of the finish bending die pair  40 . 
     In this state, the raising and lowering means  75  of the press  70  is operated, and the slider  74  is thereby lowered. The upper die set  65  shown in FIG. 2 is lowered as shown with an arrow, and the upper die  13  of the trimming die pair  12 , the upper die  26  of the coarse bending die pair  25  and the upper die  41  of the finish bending die pair  40  all descend simultaneously as shown in FIG.  4 . 
     In FIG. 4, when the upper die  13  of the trimming die pair  12  descends, the drawn forming  23  shown in FIG. 2 is sandwiched between the pressing pad  15  and the lower die  20 . And when from this state the upper die set  65  is lowered further, only the cutter  17  descends further, as shown with arrows, and the edge  23   a  of the drawn forming  23  is trimmed by a blade part  17   a  of the cutter  17 , and a trimmed forming  35  is obtained. 
     At the same time, when the upper die  26  of the coarse bending die pair  25  descends, the trimmed forming  35  is sandwiched between the pressing pad  28  and the lower die  32 , as shown in FIG.  2 . And when from this state the upper die set  65  descends further, only the coarse bend pressing die  30  descends further, as shown with arrows. As it does so, a left side peripheral part of the trimmed forming  35  is bent by the sloping bend pressing surface  30   a  of the coarse bend pressing die  30  to form the sloping bend face  49   a , and at the same time a right side peripheral part of the trimmed forming  35  is bent through a right angle by the right angle bend pressing surface  30   b  of the coarse bend pressing die  30  to form the right angle bend face  49   b , whereby a coarsely bent forming  49  is obtained. 
     And also at the same time, when the upper die  41  of the finish bending die pair  40  descends, the coarsely bent forming  49  shown in FIG. 2 is sandwiched by the pressing pad  43  and the lower die  47 . When from this state the upper die set  65  descends further, only the finish bend pressing die  45  descends further, as shown with arrows. As it does so, the first pressing surface  45   a  of the finish bend pressing die  45  presses on the moving member  52  of the finish bender  50 . The moving member  52  is thereby moved inward toward the side face of the lower die  47 , as shown with an arrow, and the finish bending blade  53  forms a finish bent edge  60   a . At the same time, the second pressing surface  45   b  of the finish bend pressing die  45  presses on the moving member  57  of the piercer  55 . The moving member  57  is thereby moved inward toward the lower die  47 , as shown with an arrow, and the punch  58  makes a hole  60   b  in the right angle bend face  49   b , whereby finished workpiece (finish bent forming)  60  is obtained. 
     Thus, in this preferred embodiment, two die pair sets, the coarse bending die pair  25  and the finish bending die pair  40 , are provided as the bending die pair. The coarse bending die pair  25  performs coarse bending of the trimmed forming  35 , and the finish bending die pair  40  performs finish bending of the coarsely bent forming  49  obtained. And these two stages of bending can be carried out simultaneously. 
     After the trimming, coarse bending and finish bending effected by one descent of the upper die set  65  have been carried out as described above, as shown in FIG. 5 the raising and lowering means  75  of the press  70  is operated and the upper die set  65  is lifted, as shown with an arrow, along with the slider  74 . 
     As shown in FIG. 6, after the upper die set  65  is lifted, the finish bent forming  60  is taken from the lower die  47  of the finish bending die pair  40 , as shown with an arrow. The finish bent forming  60  thus taken out is then carried to a subsequent step. The coarsely bent forming  49  is transferred from the lower die  32  of the coarse bending die pair  25  to the lower die  47  of the finish bending die pair  40 , as shown with an arrow. And the trimmed forming  35  is transferred as shown with an arrow from the lower die  20  of the trimming die pair  12  to the lower die  32  of the coarse bending die pair  25 . Then, a drawn forming  23  of the kind shown in FIG. 2 is transferred from a drawing die pair  80  as shown with an arrow to the lower die  20  of the trimming die pair  12 . Thereafter, workpieces are processed continuously by the steps described above being repeated in order. 
     The transferring of the formings can be carried out for example by transfer robots having suction cups. Or the formings can be transferred by hand. 
     Although in this preferred embodiment an example wherein cylinders are used as the raising and lowering means  75  has been described, the invention is not limited to this, and alternatively for example the rods  77   a ,  77   a  may be attached to a crankshaft and the crankshaft rotated by a rotational drive source to raise and lower the rods  77   a ,  77   a.    
     Obviously, various minor changes and modifications of the present invention are possible in the light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.