Abstract:
A production line including a molding press for molding a resin on a strand of material and a cutting press for cutting parts from the strand. The production line feeds the strand at a uniform rate without slack. The cutting press includes a die that moves toward and away from the strand. The die moves transversely to the strand to transport cut parts.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to automated press lines, and more particulary, to an automated press line including presses, each performing a different process, that are connected to each other by a transferring apparatus. 
     Conventionally, a number of presses, each of which performs a different process, have been arranged along a line and connected to each other by a transferring apparatus to perform a continuous operation. 
     FIG. 8 shows a typical press line. As shown in FIG. 8, a press line  50  carries out three processes. In process A, which is a press process, a material S is bent. In process B, which is a molding press process, resin is outsert molded to the material S. In process C, which is a cutting press process, molded resin products formed on the material S are cut off. FIGS.  9 ( a ),  9 ( b ), and  9 ( c ) each show the material S after completing processes A, B, and C, respectively. 
     The press line  50  includes an uncoiler  51 . A strip of material S is stamped out into a predetermined shape during a preliminary stamping process and then wound about the uncoiler  51 . The material S is fed from the uncoiler  51  by a first gripper feeder  52  to a press  53  to undergo bending (the completion of which is shown in FIG.  9 ( a )) and then to a molding press  54  to undergo resin molding (the completion of which is shown in FIG.  9 ( b )). 
     Afterward, a second gripper feeder  55  feeds the resin-molded material S to a buffer  56 , where a buffer dryer  57  dries the resin. The buffer  56  provides the material S with slack, the amount of which is constantly maintained by a loop controller  58 . 
     A third gripper feeder  59  then feeds the material S to a cutting press  60 , which cuts out molded products P from the material S at cutting positions X as shown in FIG.  9 ( c ). After the molded products P are cut off, the remaining margins of the material S are lifted away from the cutting position. A lower mold holding the molded products P is moved away from the cutting position so that the molded products P can be retrieved from the lower mold one at a time. 
     The molded products P are then inspected by an inspecting apparatus  61 . A robot hand  62  subsequently carries the molded products to an automatic stocker  63  for storage. 
     The cycle time of the cutting press  60  differs from that of the molding press  54 . Hence, if the material S were fed to the cutting press  60  from the molding press  54  in accordance with the cycle time of the molding press  54 , the material S would interfere with the cutting press  60 . This would hinder smooth delivery of the material S. 
     Therefore, the buffer  56  provides the material S with a constant amount of slack between the molding press  54  and the cutting press  60  so that the material S can be fed to the cutting press  60  from the molding press  54  in accordance with the cutting timing of the cutting press  60 . However, the buffer  56  lengthens the press line  50 . 
     When starting continuous production on the press line  50 , the material S is first fed manually through processes A, B and C. That is, the material S is fed manually during the first cycle. Furthermore, when ending continuous production, the material S in the buffer  56  must be manually fed to the cutting press  60 . As a result, the manual operations carried out when starting and ending continuous production prolong the production time. 
     The third gripper feeder  59  stops feeding the material S when detecting the trailing end of the material S. Thus, molded products P cannot be produced on the portion of the material S located between the third gripper feeder  59  and the pressing location of the cutting press  60 . This wastes some of the material S. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an objective of the present invention to provide a press line having a shorter length. 
     To achieve the above objective, the present invention provides a part production line for producing molded parts. The production line includes a plurality of machines arranged in series. Each machine performs a different operation on a continuous strand of material to produce the molded parts. The production line also includes a base and a molding press for molding resin material to sections of the strand in a molding operation cycle. The molding press is mounted on the base. A cutting press separates portions of the strand, which include the resin material, from the strand in a cutting operation cycle. The cutting press is immediately downstream from the molding press and is mounted on the base. A conveyor intermittently transfers the strand along the production line. The conveyor feeds new sections of the strand into the cutting press and the molding press at the same speed and with the same timing. 
     In a further aspect of the present invention, a method of producing parts is proposed. The method includes intermittently feeding a strand of material through a production line. The production line includes a mold press and a cutting press. The method also includes molding resin material onto portions of the strand with the mold press, and cutting parts, which include the resin, from the strand with the cutting press. The cutting includes moving a die towards an upper tool to clamp the strand between the die and the upper tool and severing the parts from the strand. The method further includes returning the die to a position spaced from the strand after the cutting operation. The severed parts are retained by the die when the die is returned to the spaced position. Furthermore, the method includes moving the die in a direction transverse to the feed direction of the strand to deliver the parts to a retrieval conveyor. 
     Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
     FIG. 1 is a side view showing a press line according to a first embodiment of the present invention; 
     FIG. 2 is an enlarged partial side view showing the presses of FIG. 1; 
     FIG. 3 is an end view showing the movement of a lower mold of the cutting press; 
     FIG. 4 is an enlarged partial cross-sectional side view showing the lower mold of the cutting press in a normal state; 
     FIG. 5 is an enlarged partial cross-sectional side view showing the lower mold of the cutting press in a cutting state; 
     FIG. 6 is an enlarged partial cross-sectional side view showing the lower mold of the cutting press after cutting; 
     FIG. 7 is a chart showing the timing of a cutting press process; 
     FIG. 8 is a side view showing a prior art press line; and 
     FIGS.  9 ( a ),  9 ( b ), and  9 ( c ) are perspective views of a strip of material showing completion of various steps of the press line operation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will now be described with reference to FIGS. 1 to  7 . The processes performed on material S by the prior art press line, the completion of which is shown in FIGS.  9 ( a ) to  9 ( c ), are also carried out in the press line of the preferred and illustrated embodiment. 
     As shown in FIG. 1, a press line  1  carries out three processes, a bending press process A, a molding press process B, and a cutting press process C. 
     A frame  3  is spaced from and downstream of an uncoiler  2 . The frame  3  includes a common base  4 . A first gripper feeder  5 , a bending press  6 , a molding press  7 , a cutting press  8 , and a second gripper feeder  9  are arranged on the base  4 . The first and second gripper feeders  5 ,  9  each serve as a transferring apparatus. An inspecting apparatus  10  and an automatic stocker  11  are arranged downstream of the second gripper feeder  9  in the frame  3 . 
     As shown in FIG. 2, the bending press  6  has a lower part  12  and an upper part  14 , and the molding press  7  has a lower part  13  and an upper part  15 . The lower parts  12 ,  13  are fixed to the base  4 . The bending press  6  includes columns  16  to support the upper part  14  in a vertically movable manner. The molding press  7  includes columns  17  to support the upper part  15  in a vertically movable manner. 
     The cutting press  8  has a lower tool  20  and an upper tool  22 . The lower tool  20  is arranged on a bolster  21 , which moves along the base  4 . Columns  23  support the upper tool  22  in a vertically movable manner. 
     As shown in FIG. 3, a cylinder  24  is arranged at one side of the lower tool  20 . The cylinder  24  moves (leftward and rightward as viewed in FIG. 3) the lower tool  20  of the cutting press  8  between a pressing location L and a retrieving location M. When the lower tool  20  is located at the pressing location L, the center axes of the lower and upper tools  20 ,  22  are aligned with each other. When the lower tool  20  is at the retrieving location M, the center axes of the lower and upper tools  20 ,  22  are offset from each other by a predetermined distance. 
     The lower surface of the upper tool  22  includes four equally spaced indentations  25  (only one is shown in FIG. 4) that are shaped to conform to the molded products P. A cam  26  is supported by the upper tool  22 . The distal end of the cam  26  includes an inclined cam surface  28 . 
     The upper tool  22  includes eight punches  27  (only two are shown in FIG.  4 ), which cut off the molded products P from the material S. The punches  27  are located to correspond to the cutting positions X. The cam  26  and the punches  27  are projected from and retracted into the upper tool  22  by a driving mechanism (not shown). 
     The lower tool  20  of the cutting press  8  includes a support plate  29  and an upper plate  30 . The support plate  29  and the upper plate  30  are arranged on the bolster  21 . 
     An air cylinder E, which serves as a lifting device, is arranged below the support plate  29 . The air cylinder E has a cylinder rod  31 , which projects from and retracts into the cylinder E. A bore  32  is formed in the support plate  29  to receive the cylinder rod  31 . 
     An L-shaped receptacle  33  extends through the upper plate  30  at a position corresponding to the cam  26 . The receptacle  33  receives the cam  26 . A slot  34  extends through the middle of the upper plate  30  near the receptacle  33 . The slot  34  connects the receptacle  33  to the bore  32  of the support plate  29 . 
     A follower block  35  is arranged on the upper surface of the support plate  29  in the receptacle  33 . One end of the follower block  35  includes an inclined follower surface  36 , which cooperates with the cam surface  28  of the cam  26 . 
     A spring  37  is arranged adjacent to the follower block  35  to constantly bias the follower block  35  in an upstream or leftward direction (as viewed in FIG.  4 ). The leftward movement of the follower block  35  is restricted when the block  35  contacts the wall of the receptacle  33 , which faces the block  35  and is perpendicular to the upper surface of the support plate  29 . 
     An intermediate plate  38  and die  39  are arranged one upon the other in the slot  34 . The intermediate plate  38  and the die  39  are vertically movable along the walls of the slot  34 . The upper surface of the die  39  is flush with the upper surface of the upper plate  30  when in a normal state. 
     A lifter block  40  extends from the lower surface of the intermediate plate  38  into the bore  32  of the support plate  29 . A support block  41  also extends from the lower surface of the intermediate plate  38  near the lifter block  40 . The support block  41  has a smaller vertical dimension that the lifter block  40 . The intermediate plate  38  is supported on the upper surface of the support plate by the support block  41  when in the normal state (the state of FIG. 4 in which the molded products P are not being cut). 
     In the normal state, the lifter block  40  is located in the bore  32  of the support plate  29 , and the intermediate plate  38  and the support plate  29  are separated from each other by distance Y 1 , which corresponds to the height of the support block  41 . A sink  42  is formed in the upper surface of the intermediate plate  38 . A bore  43  extends downward from the bottom of the sink  42 . 
     The die  39  has a bore  44 , which is connected with the bore  43  of the intermediate plate  38 , and four indentations  45  (only one is shown in FIG.  4 ), which are shaped to conform to the molded products P and are located opposite to the indentations  25  of the upper tool  22 . Eight holes  46  (only two are shown in FIG. 4) are formed on the upper surface of the die  39  at locations corresponding to the punches  22  of the upper tool  22 . Thus, four molded products P are cut off simultaneously. 
     A pin  47  is inserted through the bore  44 , the sink  42 , and the bore  43 . The lower end of the pin  47 , which extends through the lower surface of the intermediate plate  38 , is fixed to the upper surface of the support plate  29 . A head  48  is provided on the upper end of the pin  47 . A spring  49  is arranged between the pin head  48  and the bottom of the sink  42  to constantly bias the intermediate plate  38  and the die  39  downward. Contact between the support block  41  and the upper surface of the support plate  29  restricts downward movement of the intermediate plate  38  and the die  39 . In the normal state, which is shown in FIG. 4, the pin head  48  never projects above the upper surface of the die  39 . 
     As shown in FIGS. 2 and 7, lowering of the upper part  15  to close the upper and lower parts  15 ,  13  of the molding press  7  (operation S 1 ), injection and swelling (operation S 2 ), cooling (operation S 3 ), and, opening of the upper part  15  (operation S 4 ) are performed during the molding press process B to outsert mold four molded products P on the material S. 
     The molding press  7  sends the material S, on which the molded products P are formed, to the cutting press  8  upon completion of each cycle. When the molded products P are fed out of the molding press  7 , a new section of the material S, which has been bent in the preceding press process A by the bending press  6 , is sent into the molding press  7 . The molding press  7  then performs the molding press process B on the new section. 
     While the molding press process B is performed on the new section of the material S, the cutting press process C and retrieval of the four cut-off molded products P are performed within a time period shorter than the cycle time of the molding press process B. After the retrieval of the molded products P, new molded products P are sent into the cutting press  8 . These operations are repeated until the continuous production is completed. 
     The cutting of the molded products P, which have been molded on the material S during the molding press process B, will now be described with reference to FIG.  3  and FIGS. 5 to  7 . The cylinder  24 , which is located on one side of the lower tool  20 , is first driven to move the lower tool  20  from location M, which is offset from the upper tool  22 , to location L, which is aligned with the upper tool  22  (operation T 1 ). 
     The air cylinder E located below the support plate  29  is then driven to project the cylinder rod  31  into the bore  32 . The cylinder rod  31  contacts and lifts the lifter block  40 , which is located in the bore  32 , into the slot  34 . This moves the intermediate plate  38  and the die  39  upward against the biasing force of the spring  49  (operation T 2 ). 
     As a result, the die  39  moves above the upper surface of the upper plate  30 , so that the upper surface of the die  39  contacts the material S. The lower halves of the molded products P are received in the indentations  45  of the die  39 . In this state, the intermediate plate  38  and the support plate  29  are separated from each other by distance Y 2 , which is substantially the same as the height of the follower block  35 , as shown in FIG.  5 . This permits the follower block  35  to move into the space between the intermediate plate  38  and the support plate  29 . 
     The upper tool  22  is then lowered by a driving means (not shown) toward the lower tool  20  to clamp the tools  20 ,  22  together (operation T 3 ). In this state, the material S is held between the upper tool  22  and the die  39 . The upper halves of the molded products P are received in the indentations  25  of the upper tool  22 . 
     When the upper tool  22  is lowered and the tools  20 ,  22  are clamped together, the cam  26  is lowered into the receptacle  33  of the lower tool  20 . This presses the cam surface  28  of the cam  26  against the follower surface  36  of the follower block  36 , which moves the follower block  35  toward the right (as viewed in FIGS. 4 to  6 ). Hence, the follower block  35  is forced into the slot  34  between the intermediate plate  38  and the support plate  29  against the biasing force of the spring  37 . 
     In this state, the punches  27  of the upper tool  22  are lowered toward the die  39  so that they pierce the material S at the cutting positions X (FIG.  9 ( b )) and cut off the four molded products P simultaneously. After piercing the material S, the punches  27  enter the corresponding holes  46 . When cutting off the molded products P, the downward force applied to the die  39  is transmitted by the intermediate plate  38  and the follower block  35  to the support plate  29 . 
     After the molded products are cut off, the cam  26  and the punches  27  are retracted into the upper tool  22  and the upper tool  22  is lifted away from the lower tool  20  to unclamp the tools  20 ,  22  (operation T 4 ). 
     As the cam  26  retracts, the biasing force of the spring  37  returns the follower block  35  to its original position, which is shown in FIG.  6 . This permits the intermediate plate  38  and the die  34  to move downward along the walls of the slot  34 . 
     The air cylinder E below the support plate  29  is then driven to retract the cylinder rod  31 . With the assistance of the biasing force of the spring  49 , this lowers the intermediate plate  38  and the die  39  and returns the support block  41  to a position contacting the upper surface of the support plate  29  (operation T 5 ). 
     The cut-off molded products P are held in the indentations  45  of the die  39  as the die  39  moves downward. As shown in FIG. 6, this creates a gap Z between the molded products P and the material S and permits the material S to move without interference with the lower tool  20 . 
     Afterward, the cylinder  24  is driven to move the lower tool  20  along the base  4  (toward the left as viewed in FIG.  3 ) to location M (operation T 6 ). This enables retrieval of the molded products P. 
     A robot arm R (FIG.  3 ), which is located near the frame  3 , is then moved to a position above the molded products P (operation T 7 ). 
     Subsequently, the robot arm R simultaneously picks up the four molded products P, carries the products P to the inspecting apparatus  10 , and then stores the products P in the automatic stocker  11  (operation T 8 ). 
     After completing the retrieval of the molded products P, the robot arm R is returned to its original position (not shown). 
     Operations T 1  to T 9  are repeated until the continuous operation is completed. 
     The preferred and the illustrated embodiment has the advantages described below. 
     The lower parts  12 ,  13  and the lower tool  20  of the respective presses  6 ,  7 ,  8  are arranged on a common base  4 , and the buffer  56  of the prior art is not necessary. Therefore, the length of the press line  1  is shortened compared to the prior art. Accordingly, the press line  1  occupies less floor space. 
     The shortened press line  1  decreases the time required for manual operation, which is required when starting continuous production. Furthermore, the material S need not be fed out of a buffer manually. This also decreases the manual operation time when starting continuous production. 
     The need for the third gripper feeder  59 , which is used in the prior art, is eliminated. Thus, molded products P are produced from the material S even at locations close to the trailing end of the material S. Thus, material S is not wasted. 
     The lower parts  12 ,  13  and the lower tool  20  of the respective presses  6 ,  7 ,  8  are arranged on the same base  4 . Thus, the presses  6 ,  7 ,  8  form a single apparatus, which simplifies maintenance. 
     The lower parts  12 ,  13  and the lower tool  20  of the respective presses  6 ,  7 ,  8  are arranged on the same base  4 . Thus, the need for the buffer  56 , the loop controller  58 , and the third gripper feeder  59 , which are used in the prior art, is eliminated. This decreases equipment costs. 
     After cutting off the molded products P, a gap Z is created between the material S and the molded products P, which are held on the die  39 . Thus, the molded products P can be retrieved without interference between the material S and the lower tool  20  of the cutting press  8  even when the molding press process B is being performed. 
     When cutting off the molded products P, the cutting pressure applied to the lifted die  39  is transmitted by the follower block  35 . This prevents damage to the die  39 . 
     After cutting off the molded products P, the lower tool  20  is moved from location L to location M on the bolster  21 . This simplifies the retrieval of the cut-off molded products. 
     Four molded products P are retrieved simultaneously whereas the molded products P are retrieved one at a time in the prior art. This improves production efficiency. 
     The die  39  is lifted and lowered by the air cylinder E and the spring  49 , which are inexpensive parts. This decreases the cost of the press line  1 . 
     The cam  26  and the follower block  35  are formed to receive the forces applied to the lifted die  39 . This simplifies the structure of the lower tool  20  and the upper tool  22 . 
     It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms. 
     The support block  41  may be replaced by an elastic member, such as a rubber cushion. Furthermore, a spring, a hydraulic damper, or the like may be arranged between the support block  41  and the intermediate plate  38 . Such structures would absorb the impact produced when lowering the die  39 . 
     The springs  37 ,  49  may be replaced by hydraulic dampers, or the like. This would provide the same advantages as the preferred and illustrated embodiment. 
     The intermediate plate  38  and the die  39  may be formed integrally with each other. This would decrease the number of parts. 
     The type of uncoiler  2  employed is not limited. For example, the uncoiler  2  may have a single-mandrel type structure or a dual-mandrel type structure. The advantages of the preferred and illustrated embodiment would be obtained regardless of the type of uncoiler  2  used. 
     Furthermore, the uncoiler  2  may be replaced by a cradle straightener and the advantages of the preferred and illustrated embodiment would still be achieved. 
     The first gripper feeder  5  may be replaced by a roll feeder or an air feeder. Such feeders would also send the material S to the pressing positions of each press  6 ,  7 ,  8  in accordance with the pressing timing. 
     The press line  1  may include a coil car, which automatically mounts the material S on the uncoiler  2 , and a leveller for straightening the material S. The advantages of the preferred and illustrated embodiment would still be achieved regardless of the additional equipment. 
     The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.