Patent Abstract:
A transfer device having high productivity and is compact. The present invention uses cross bars that have a blank attachment member that are suitable for transferring large blank materials that, prior to processing, do not have rigidity. These large blank materials have a tendency to sag in the center and are difficult to transport. The present invention also jointly uses fingers that are suitable for rapid transport of blank materials that, after processing, are molded and have rigidity.

Full Description:
This is a continuation-in-part of application Ser. No. 09/793,692 filed Feb. 26, 2001, now abandoned. 
    
    
     BACKGROUND OF THE PRESENT INVENTION 
     1. Field of the Invention 
     The present invention relates to a transfer device equipped with feed bars having fingers for gripping an end part of a blank. The present invention also relates to a transfer device equipped with cross bars having a blank attachment member. 
     2. Description of the Related Art 
     For transfer devices having a feed bar placed in the blank transfer direction, the typical method of transfer is to grasp the end part of a blank material with a clamping motion of a pair of feed bars that are arranged parallel to each other. For example, the operation can be conducted at an approximate stroke of 45 times per minute. However, as the front-back measurement of the blank material becomes larger (for example, 1,300 mm or greater) there is sagging of the center portion of the blank material because the blank material loses rigidity. Transfer is especially difficult in the steps prior to the processing the blank material, e.g. bending or the like. 
     With large blank materials (for example, blank materials of 2,500 mm or greater), there is the cross-bar method in which transfer occurs by having a blank attachment member that attaches to the upper surface of the blank material. With a lifting and lowering motion, after attaching to the blank material, the cross bars transfer the blank material to the next stage. The cross-bars are held in a position that does not interfere with the die during processing, and after the processing, they return to the previous stage to transport the next blank material. 
     For the cross-bar method as described above, a large amount of time is needed for the motions for one cycle, and as a result, the mechanical device averages only 10 strokes per minute. Compared to the transfer by the previously described fingers, the productivity is reduced. Furthermore, a driving device for moving the cross bars must be provided on the feed bars. As a result, the mechanical device becomes large. 
     Thus, there is still a need in the art to develop a transfer device that can move large blank materials at a high rate of speed and is of a compact size. 
     OBJECT AND SUMMARY OF THE INVENTION 
     It is the foregoing and various other drawbacks of the prior art which the present invention seeks to overcome by providing a transfer device that has high productivity and is compact. 
     The present invention uses cross bars that have a blank attachment member and that are suitable for transferring large blank materials that, prior to processing, do not have rigidity, sag in the center and are difficult to transport. Additionally, the present invention also jointly uses fingers that are suitable for rapid transport of blank materials that, after processing, are molded and have rigidity. 
     The transfer device of the present invention has a construction in which two types of transfer devices are jointly used. These two types are cross bars that have a blank attachment member and fingers for gripping the blank end parts. The invention is a transfer device having a pair of parallel arranged feed bars. 
     Two types of transferring devices are used concurrently. One type of transferring device is cross bars that span the feed bars and that have a blank attachment member and are used for transferring a blank material, which has been brought to an idle stage of the transfer device, to a next stage. A second type of transferring device is fingers for gripping blank end parts and are used for each downstream stage from the second stage and beyond the feed bars. Further, the transfer device may include a rack formed in a center portion of the pair of cross bars. One of the facing ends of cross bars are fixed on guides, which are affixed to the upper surfaces of the feed bars, and the other ends are slidably guided. In addition, a pinion is rotatably provided on a plate that is joined near the center part of the cross bars, and the pinion meshes with the rack to construct a rack-pinion mechanism. 
     The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of a specific embodiment thereof, especially when taken in conjunction with the accompanying drawings wherein like reference numerals in the various figures are utilized to designate like components, and wherein: 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a plan view of a transfer device according to the present invention; 
     FIG. 2 is an enlarged detail of the top view of the transfer device of FIG. 1; 
     FIG. 3 is a longitudinal section taken along lines  3 — 3  of FIG. 2; 
     FIGS. 4A-4F illustrate the sequence of steps performed by the transfer device of the present invention; and 
     FIG. 5 is a timing chart indicating the actions of the transfer device and the slide of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, an embodiment of the present invention is illustrated. FIG. 1 illustrates a press machine  50  equipped with a bed  42 . A crown is supported on this bed  42  via a column  1 . Bolster  2  is located on top of bed  42 , the bolster  2  may be fixed or may shift location. A slide that can move vertically with respect to bolster  2  is provided. A plurality of lower molds and upper molds are attached on the opposing surfaces of bolster  2  and the slide. In addition, pairs of feed bars  5 ,  6 ,  7  that transport the blank materials from die to die are arranged parallel to each other and are placed on top of the bolster  2 . 
     Feed rails  52  are constructed from three sections of feed bars  5 ,  6 ,  7 . Feed bars  5  and feed bars  6  are detachable from each other by a joint  12 . Similarly, feed bars  6  and feed bars  7  are detachable from each other by a joint  13 . This configuration is convenient for removing only sections of the press machine  50  at a time. For example, only feed bars  6  need to be removed together with the moving bolster  2  when exchanging dies. 
     A slider  14  that guides feed rails  52  in the transfer direction is linked to feed bars  7 . On slider  14 , there are upright pins  15 , and they can be inserted into holes opened on the end of feed bars  7 . 
     Furthermore, slider  14  conducts an advance/return motion by a rack-pinion construction having a servo motor  16  as the driving means. In conjunction with this motion, feed rails  52  also conduct an advance-return motion (refer to FIG.  2 ). 
     In addition, feed bars  6  and feed bars  7  are received by U-shaped guide parts  8  and guide parts  9 . Guide parts  8 , and  9  conduct a clamp-unclamp motion (refer to FIG. 2) by a ball-screw mechanism that has a driving means of a servo motor that is provided on a clamp lift unit  3  and clamp lift unit  4 . In addition, guide parts  8  and guide parts  9  conduct a lifting and lowering motion (illustrated in FIG. 3) by a rack-pinion mechanism that has as a driving means, and a different servo motor inside clamp lift unit  3  and clamp lift unit  4 . 
     The above embodiment allows the feed bars  5 ,  6 , and  7  to conduct three-dimensional motions. However, another embodiment will allow feed bars  5 ,  6 , and  7  to conduct two-dimensional motions in relation to a horizontal plane. In this embodiment, a cylinder  18   a  is provided on blank attachment member  18 , that is attached to a plate  20  provided on cross bar  17 . This arrangement allows the press machine  50  to conduct the lifting and lowering motion of only blank attachment member  18 . 
     In addition, a conveyor belt  10  and a conveyor belt  11  are installed on the transfer device for bringing in and taking out the blank material. Conveyor belt  10  brings in blank materials to idle stage  23  at a constant pitch. Conveyor belt  11  brings out the product that has completed the final processing to a product receiver. 
     Feed bars  6  are equipped with cross bars  17  and fingers  22  for gripping the blank end part. In conjunction with the three dimensional or two dimensional movement of feed rails  52 , cross bars  17  and fingers  22  for gripping the blank end part to transfer the blank materials to the next stage in sequence. 
     Guides  21  for installing cross bars  17  are affixed to feed bars  6 . One of the facing ends A of the pair of crossbars  17  are affixed to guide  21 . In addition, the opposite the facing ends B of cross bars  17  are slidably guided by guide  21 . 
     A plate  20  is provided on cross bars  17 . In addition, a blank attachment member  18 , such as a vacuum cup or magnet, is provided on plate  20 . A rack  19   b  is formed in the center part of cross bars  17 . The rack meshes with a pinion  19   a  that is rotatably provided on plate  20 , and a rack and pinion mechanism  19  is constructed. Blank attachment member  18  is always maintained at a middle point between feed bars  6 . 
     Referring to FIGS. 2 and 3, a detailed drawing of the principal parts in the area of blank attachment member  18  and plate  20  is shown. FIG. 2 illustrates a detailed drawing in which the principal parts of FIG. 1 are enlarged. FIG. 3 is a longitudinal cross-section of FIG. 2 viewed across line  3 — 3 . Furthermore, referring to FIGS. 2 and 3, both are spilt by dividing line X—X, the illustration to the right half of dividing line X—X illustrates the condition when feed bars  6  are unclamped, and the illustration to the left half of dividing line X—X illustrates the condition when feed bars  6  are clamped. 
     As described above, facing ends A of cross bars  17  are anchored to guide  21 . The other facing ends B are slidably guided by bushing  21   a  of guide  21 . Also, plate  20  is slidably provided on two cross bars  17 . A pinion gear  19   a  is provided at the center of plate  20 . A pin  26  is affixed to pinion gear  19   a . Pin  26  is rotatably supported by bearings  27 ,  28 . Therefore, pinion gear  19   a  is rotatably supported. Rack  19   b  is provided at the center part of cross bars  17 . Pinion gear  19   a  and rack  19   b  engage to construct a rack pinion mechanism  19 . 
     Furthermore, as described above, blank attachment member  18  is provided on plate  20 . Blank attachment member  18  is provided at Four sites. In the present embodiment, blank attachment member  18  is formed by a vacuum cup. Blank attachment member (vacuum cup)  18  is affixed to a piston rod  18   b  which joins with cylinder  18   a . A vacuum generating device  18   c  provided at the top of vacuum cup  18  creates a vacuum in the interior of vacuum cup  18  when air enters vacuum generating device  18   c.    
     An air circuit  31 , which includes electromagnetic valve  29  and an air source  30 , is connected to cylinder  18   a . Piston rod  18   b  and blank attachment member (vacuum cup)  18  which is affixed thereto move up and down by the switching of electromagnetic valve  29 . Thus, when electromagnetic valve  29  is in condition  29   a , air will enter the upper chamber of cylinder  18  and blank attachment member (vacuum cup)  18  is lowered. In addition, because air also enters vacuum generating device  18   c , the inside of blank attachment member (vacuum cup)  18  becomes a vacuum, and blank material is attached to blank attachment member (vacuum cup)  18 . 
     When electromagnetic valve  29  is in condition  29   b , air enters the lower chamber of cylinder  18   a . As a result, blank attachment member (vacuum cup)  18  rises. At this time, because air does not enter vacuum generating device  18   c , the attachment is released. 
     The series of motions of the transfer device is now described. The blank material that has been transferred to idle stage  23  by conveyor belt  10  is brought to first stage  24  by blank attachment member  18 . The blank material that has been molded by a die is transferred from first stage  24  to second stage  25  by fingers  22  for gripping the blank end part. Similarly, the product is molded in sequence at each of the stages downstream from second stage  25  (i.e third stage  40  and fourth stage  41 ). The final product is brought to a product receiver by conveyor belt  11 . 
     Referring to FIGS. 4A through 4F, the sequence of steps performed by the transfer device of the present invention are illustrated in further detail. FIG. 4A illustrates the principal parts of the transfer device as viewed from the side. The sequence from  4 A- 4 F, consists of blank material W being transported from idle stage  23  to first stage  24 . 
     As illustrated in FIG. 4A, blank material W is transported to idle stage  23 , and a blank material that has been pressed (partially fabricated product W′) is mounted at the first stage  24 . Presently, feed bar  6  is in the “down” position. In addition, a clamping motion is conducted, and partially fabricated product W′ is held between fingers  22 . By the action of rack-pinion mechanism  19 , plate  20  is maintained at a center position in the clamp-unclamp direction (i.e. along the midline between feed bars  6 ). 
     FIG. 4B illustrates the next series of steps. Almost simultaneously with the clamping action of feed bar  6 , blank attachment member (vacuum cup)  18  is lowered. Once lowered, it is possible to attach blank material W to blank attachment member (vacuum cup)  18 . Thus, blank material W is attached to attachment member (vacuum cup)  18 . 
     FIG. 4C illustrates feed bar  6  being raised by a lifting motion. Blank material W is attached and held by blank attachment member (vacuum cup)  18 . Partially fabricated product W′ is held between fingers  22 . 
     Next, feed bar  6  advances up the line. Also, conveyor  10  (FIG. 1) transports the next blank material W to idle stage  23  (see FIG.  4 D). 
     FIG. 4E illustrates feed bar  6  performing a downward motion. Blank material W is transported to first stage  24 . Partially fabricated product W′ is transported to second stage  25 . 
     Lastly, the suction is released from the blank attachment member (vacuum cup)  18 , and blank attachment member  18  is raised. Afterwards, feed bar  6  is unclamped, and the partially fabricated product W′ is released from its hold. Thereupon, a slide of a press (not shown) is lowered and pressing is conducted at each of the stages. At this time, feed bar  6  has a returning motion, and after pressing, the conditions become restart as illustrated in FIG.  4 A. 
     As described above, by linking the motions of FIGS. 4A-4F with the motions of the slide (upper mold) of the press (not shown), pressing can be conducted continuously. 
     Furthermore, by the clamping motion of feed bar  6  and the lowering motion of blank attachment member (vacuum cup)  18 , the timing for the motions is set according to the dies and product to be manufactured so as to avoid interference. 
     FIG. 5 illustrates a timing chart that shows when the motions of the slide of the press are combined with the motions of feed bar  6  and blank attachment member  18 . This timing matches the movements illustrates in FIGS. 4A-4F. The horizontal axis is the crank angle of the press. According to the timing chart of FIG. 5, the crank angle for each of the stages illustrated in FIGS. 4A-4F is approximately the following: FIG. 4A is at 225 degrees, FIG. 4B is at 260 degrees, FIG. 4C is at 270 degrees, FIG. 4D is at 300 degrees, and FIG. 4E is at 60 degrees, FIG. 4F is at 100 degrees. 
     The embodiment in FIGS. 4A-4F illustrate a three dimensional motion of the feed bar  6 . However, two-dimensional motion is also possible. Two-dimensional motion is defined as the feed bar  6  clamping and holding the partially fabricated product. In addition, blank attachment member  18  is lowered, attaches to the blank, is raised, then advances. Feed bar  6  then unclamps, and the partially fabricated product is released (mounted). In addition, blank attachment member  18  is lowered, the attachment released, and then blank attachment member  18  is raised. 
     Furthermore, with the above embodiment, a vacuum cup is used for blank attachment member  18 . However, as described above, a magnet may also be used. Thus, it is known by those skilled in the art that the optimal blank attachment member is selectable according to the type of blank material. 
     In the present invention, cross bars  17  having blank attachment member  18  are used for carrying the blank material to first stage  24  when sagging of the blank material is a concern. For second stage  25  and beyond, the blank material is molded and rigid, and, thus suitable fingers  23  are used for the transfer of these blank materials. In other words, with one machine, two types of transfer devices are used together. As a result, there are advantages in terms of cost and high productivity in the various processing from small blank materials to large blank materials. 
     Thus, while there have been shown, described, and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions, substitutions, and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is expressly intended that all combinations of those elements and/or steps which perform substantially the same function, in substantially the same way, to achieve the same results are within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated. It is also to be understood that the drawings are not necessarily drawn to scale, but that they are merely conceptual in nature. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Technology Classification (CPC): 1