Abstract:
A flash removing apparatus is provided which has a pair of blades driven by an actuator through a linkage assembly, simultaneously and in opposite directions, between a bottle receiving position and a closed position to aid in removing flash from a plastic product disposed on the blades. Preferably, the blades can also be moved to a fully open position to permit a bottle to pass between the blades and increase manufacturing flexibility and efficiency of the apparatus. The linkage assembly has a center link rotatable about a fixed pivot and at least one link arm connected to the center link and operably connected to the actuator to unfold and fold the linkage assembly in response to movement of the actuator between its advanced and retracted positions. The folding and unfolding of the linkage assembly moves the blades between their open and closed positions in cycles to remove flash from consecutive plastic products.

Description:
FIELD OF THE INVENTION 
     The field of the invention relates to the manufacture of molded plastic products, and more particularly, to a flash removal apparatus for molded plastic products. 
     BACKGROUND OF THE INVENTION 
     In manufacturing molded hollow plastic products, it is common to use a blow molding process. Blow molding inherently leaves flash on the bottle where the molten parison material is trapped between the mold halves. To achieve the desired final appearance and finish, the flash needs to be removed. 
     Flash on the bottom of the bottle has been removed with a pair of blades by disposing the bottle on top of the blades with the flash disposed between the blades. One blade is fixed and the other blade is driven between advanced and retracted positions defining closed and open positions, respectively, of the blades. Undesirably, with the stationary blade in position to receive the bottle thereon, a bottle cannot be rejected at the flash removal workstation before the flash removal operation is performed. Additionally, the arrangement with one movable blade may not properly or completely remove the flash requiring the bottle to be rejected or a secondary flash removal operation which increase the time and cost to manufacture the bottles. 
     SUMMARY OF THE INVENTION 
     A flash trimming assembly is provided which has a pair of blades driven by an actuator through a linkage assembly, simultaneously and in opposite directions, between a bottle receiving position and a closed position to aid in removing flash from a plastic product disposed on the blades. Preferably, the blades can also be moved to a fully open position to permit a bottle to pass between the blades and increase manufacturing flexibility and efficiency of the apparatus. The linkage assembly has a center link rotatable about a fixed pivot and at least one link arm connected to the center link and operably connected to the actuator to unfold and fold the linkage assembly in response to movement of the actuator between its advanced and retracted positions. The folding and unfolding of the linkage assembly moves the blades between their open and closed positions in cycles to remove flash from consecutive plastic products. 
     In one embodiment, the flash trimming assembly is incorporated into a rotary blow-molding machine, such as may be used for forming plastic bottles. Freshly molded bottles are positioned on the blades with the flash to be removed from a bottle received between the blades. Thereafter, the blades are moved to their closed position to engage the bottle flash from opposed sides, and the bottle is moved relative to the blades to remove the flash from the bottle. Preferably, to facilitate removing bottles which do not meet desired specifications from the system, the blades can be moved to their fully open position permitting a bottle to pass between them without removing any flash from the bottle. 
     Accordingly, one advantage of incorporating opposing blades that move simultaneously is the ability to accurately and repeatedly clamp the bottle flash to facilitate satisfactory removal of the flash. 
     Another advantage of the present invention is to provide opposed blades driven simultaneously in opposed directions of the same stroke length by a single, linear actuator. This provides a more efficient, cost-effective apparatus. 
     Another advantage of the present invention is to provide for an efficient process for ejecting or rejecting bottles from the molding system. By moving the opposing blades to their filly open position, the bottles can be removed from the system quickly and easily. 
     Another advantage of the present invention is to reduce scrap, improve efficiency, and reduce associated costs in manufacturing plastic bottles. 
     Another advantage of the present invention is to provide a reliable, efficient apparatus to remove flash which is of relatively simple design and economical manufacture and assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features and advantages of this invention will be apparent from the following detailed description of the preferred embodiment and best mode, appended claims, and accompanying drawings in which: 
     FIG. 1 is a side view of a portion of a rotary blow molding machine having a bottle flash trimming assembly embodying this invention and illustrating blades of the assembly in an intermediate, bottle receiving position; 
     FIG. 2 is a side view of the blow molding machine of FIG. 1 illustrating the blades of the flash trimming assembly in their closed position engaging tail flash on a bottle; 
     FIG. 3 is a plan view of a portion of a rotary blow molding machine of FIG.  1  and the bottle flash trimming assembly with the blades in a fully open position; 
     FIG. 4 is a side view of the flash trimming assembly; 
     FIG. 5A is a plan view of a linkage assembly with the blades of the flash trimming assembly in their fully open position; 
     FIG. 5B is a plan view of the linkage assembly with the blades of the flash trimming assembly in their closed position, and 
     FIG. 6 is a side view of the linkage assembly in the position shown in FIG.  5 B. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring in more detail to the drawings, FIGS. 1-6 illustrate a portion of a rotary blow molding machine  10  used to form plastic bottles  12  and having a flash trimming workstation  14  wherein flash  16  along a bottom  18  of the bottle  12  is removed from each bottle  12 . As best shown in FIGS. 5A and 5B, the workstation  14  has a flash trimming assembly  20  comprising first and second blades  22 ,  24  driven by an actuator  26  through a linkage assembly  28  in opposed directions from a bottle receiving position, as shown in FIG. 1, to a closed or flash engaging position as shown in FIG.  2 . As shown in FIGS. 1 and 2, the workstation  14  has a pusher nest assembly  30  and transport guide assembly  32  which move the bottles  12  relative to the blades  22 ,  24  and transfer them to a conveyor  33  which moves the bottles  12  to downstream processing workstations. 
     Generally, in the manufacture of a plastic bottle  12 , as best shown in FIG. 1, a bottle take out assembly  34  transfers a molded bottle  12  from a bottle mold cavity (not shown) to the flash trimming workstation  14  and places the bottle  12  on the blades  22 ,  24  of the flash trimming assembly  20  which are in their bottle receiving position. A stripper assembly  36  is advanced to ensure the bottle  12  is removed from the take out assembly  34  when the takeout assembly  34  is retracted from the bottle  12  and the pusher nest assembly  30  and the transport guide assembly  32  converge towards and engage opposed sides of the bottle  12  to hold it in an axially upright position. Next, the blades  22 ,  24  of the flash trimming assembly  20  are driven to their fully closed position shown generally in FIG. 2, such that the strip of flash  16  along the bottom  18  of the bottle  12  is captured between the blades  22 ,  24 . The pusher nest assembly  30  is then advanced to push the bottle  12  from the blades  22 ,  24  to a conveyor, which carries the bottle  12  to a downstream workstation. To reset the flash trimming workstation  14 , the flash trimming assembly  20 , stripper assembly  36 , pusher nest assembly  30  and transport guide assembly  32  are each retracted to permit the next bottle  12  to be processed. 
     In more detail, the bottle take out assembly  34  has a take out wheel (not shown), a plurality of take out arms  40  each carried at one end  42  on the take out wheel, and a take out pin  44  disposed at a free end  46  of each take out arm  40 . The take out wheel is rotatably indexed to sequentially index the take out arms  40  relative to various workstations of the blow-molding machine  10 . Each take out arm  40  is driven by a pneumatic cylinder  48  between an extended and a retracted position to vary the position of its take out pin  44  relative to the take out wheel. Each take out pin  44  can be expanded radially outwardly to increase its effective outer diameter and contracts radially inwardly to reduce its outer diameter relative to the expanded position, preferably under pneumatic control, to be receivable in and selectively engageable with a bottle mouth  50 . 
     The stripper assembly  36  has an actuator  52 , which is preferably a pneumatic cylinder, supported by a frame  54  of the blow molding machine  10 , a stripper arm  56  driven between extended and retracted positions by the actuator  52 , and a stripper fork  58  carried by the stripper arm  56  for co-movement therewith. The stripper fork  58  has two times  60  extending in a generally horizontal plane that are spaced apart a predetermined distance to be received around a bottle neck  62  to ensure that the bottle  12  is removed from the take out pin  44  of the take out assembly  34  when the take out assembly  34  is withdrawn from the bottle  12 . 
     As best shown in FIGS. 1,  2  and  4 , the pusher nest assembly  30  has an actuator  64  carried by the frame  54 , a rod  66  driven between extended and retracted positions by the actuator  64 , a plate  68  carried by the rod  66  and adapted to engage a side portion of the bottle  12 , an arm  70 , and a bumper  72  carried by the arm  70 . The pusher nest assembly  30  is used to help remove flash  16  from the bottle  12  and to move the bottle  12  from the flash trimming workstation  14  to the conveyor. 
     As best shown in FIGS. 1-3, the transport guide assembly  32  has an actuator  74  carried by the frame  54 , a rod  76  driven between retracted and advanced positions by its actuator  74 , a mounting plate  78  connected to an end  80  of the rod  76 , one or more arms  82  connected to and extending from the mounting plate  78 , a suction cup  84  at a free end  86  of each arm  82 , a limit arm  88 , and a stop or bumper  90  carried by the limit arm  88 . The suction cups  84  are adapted to engage a side portion of the bottle  12  in the flash trimming workstation  14  and may communicate a low pressure or vacuum source with the bottle  12  through a passage in each arm  82  to help to maintain engagement of the cups  84  with the bottle  12 . One end  94  of the limit arm  88  is threaded and receives a nut  96  which cooperates with a proximity sensor  98  carried on the stationary frame  54  to indicate when the transport guide assembly  32  is fully retracted. 
     The flash trimming assembly  20  has first and second blades  22 ,  24  driven simultaneously in opposed directions by the single actuator  26  having a linear stroke to facilitate removing flash  16  from a molded plastic article. The first blade  22  is carried by a first carriage  100  which has a base  102 , and a mounting plate  104  on the base  102  and to which the first blade  22  is fixed by capscrews  106  (FIGS.  5 A and  5 B). The base  102  extends between and is slidably received on a pair of spaced apart, parallel rails  108 . As shown in FIG. 6, the base  102  of the first carriage  100  has a through bore  110 , a pair of counterbores  112  and a bushing  114  in each counterbore  112 . As shown in FIGS. 3,  5 A and  5 B, to facilitate its slidable movement along the rails  108 , the base  102  is preferably fixed to bearing blocks  116  slidably received on the rails  108 . The first blade  22  has a serrated leading edge  118  to facilitate severing or shearing off the flash  16  from the molded article. The first blade  22  is driven toward the second blade  24  by the actuator  26  and the linkage assembly  28  connected between the actuator  26  and first carriage  100 . 
     As shown in FIGS. 1,  2  and  4 , the second blade  24  is carried by a second carriage  120  which has a base  122  and a mounting plate  124  on the base  122  and to which the second blade  24  is fixed by cap screws  125 . As best shown in FIGS. 5A and 5B, the base  122  is operably connected to a tie bar  126  for co-movement therewith by the pair of rails  108  extending between them. The rails  108  are slidably received through a pair of bearing blocks  127  attached to the frame  54 . The tie bar  126  is in turn connected to the linkage assembly  28  and is driven by the actuator  26  to move the second blade  24 . The second blade  24  preferably also has a serrated leading edge  130  to facilitate severing or shearing off the flash  16  from the molded article. 
     The actuator  26  may be a pneumatic cylinder and is carried by the frame  54 . As best shown in FIG. 5A, the actuator  26  has an actuator rod  132  driven between retracted and extended positions to move the blades  22 ,  24  between their fully open and fully closed positions. The actuator rod  132  has a free end  134  extending out of an actuator housing  136  and connected to a coupler  138  which, in turn, is connected to the tie bar  126 . The tie bar  126  in turn, is connected to a first link  140  of the linkage assembly  28 . As best shown in FIG. 6, the tie bar  126  has a through bore  142  and a pair of counterbores  144  opening to opposed sides of the tie bar  126  and in each of which a bushing  148  is disposed to facilitate pivotal movement of the first link  140  relative to the tie bar  126 . 
     The first link  140  is preferably defined by a pair of parallel plates  150  and has a first end  152  having aligned bores  154  through both plates  150  for connection to the tie bar  126  by a bolt  156  passing through the aligned bores  154 , the bushings  148 , and the through bore  142  in the tie bar  126 . A nut  158  on one end retains the bolt  156 . A second end  162  of the first link  140  has aligned bores  164  through both plates  150  to permit connection with a center link  166  in a similar manner. 
     The center link  166  has a first end  172  with a through bore  168  and a pair of counterbores  176  with a separate bushing  180  in each of the counterbores  176 . To connect the first link  140  to the center link  166 , a bolt  182  extends through the aligned bores  164  of the second end  162  of the first link  140  and through the bore  168  of the center link  166  and its associated bushings  180 . To permit connection of the center link to a second link  200 , a through bore  170 , a pair of counterbores  178  and a separate bushing  181  in each counterbore  178  are provided in a second end  176  of the center link. The center link  166  rotates about a pivot pin  184  received through a through bore  186  between the first and second ends  172 ,  174  of the center link  166 . The pivot pin  184  is fixed to a base  188  by a nut  190  on one end and has an enlarged head  194  at its other end bearing on the center link  166 . The base  188  is in turn fixed to the frame  54  by several cap screws  196 . Desirably, to journal the center link  166  for rotation, one or more bushings  198  are received in the through bore  186 . 
     A second link  200  of the linkage assembly  28  has a pair of spaced apart parallel plates  202  having a first end and second end  204 ,  206  and is connected at the first end  204  to the second end  174  of the center link  166  by a bolt  207  extending through aligned bores  208  through each plate  202 , the bushings  181  and the bore  170  through the center link  166 . Aligned bores  210  through both plates  202  at the second end  206  of the second link  200  and the bore  110  through the base  102  of the first carriage  100  receive a bolt  212  in assembly to pivotally connect the second link  200  to the base  102  which carries the first blade  22 . 
     So connected, the linkage assembly  28  is connected to the first blade  22  via the first carriage  100  and to the second blade  24  via the tie bar  126  which is operably connected to the second blade  24 . As best shown in FIGS. 5A and 5B, the linkage assembly  28  is driven by the actuator  26  between a folded or retracted position (FIG. 5A) and an unfolded or extended position (FIG. 5B) when the actuator  26  is in its extended position and retracted position, respectively. 
     As the rod  132  is moved by the actuator  26  from its extended position shown in FIG. 5A to its retracted position shown in FIG. 5B, the tie bar  126  is pulled towards the actuator  26  and the second blade  24  is pulled toward the first blade  22 . Simultaneously, movement of the tie bar  126  causes movement of the first link  140  connected thereto which in turn causes the center link  166  to rotate clockwise about the pivot pin  184  (as viewed in FIGS.  5 A and  5 B). This rotation of the center link  166  drives the second link  200  away from the actuator  26  to move the first blade  22  towards the second blade  24 . Desirably, the first and second blades  22 ,  24  are moved relative to each other at the same rate and over the same stroke length to provide accurate engagement of the blades  22 ,  24  with the flash  16  on a bottle  12 . In the embodiment shown and described, this is accomplished by pivoting the center link  166  midway between its ends  172 ,  174  and by providing the first and second links  140 ,  200  of the same effective length. 
     The actuator  26  retracts the rod  132  until the first and second blades  22 ,  24  are in their fully closed position shown in FIG.  5 B. When the blades  22 ,  24  are in their closed position, the linkage assembly  28  is unfolded or extended with the first end  152  of the first link  140  and the second end  206  of the second link  200  at their furthest distance from one another. To open the first and second blades  22 ,  24  the actuator  26  drives the rod  132  toward its extended position which drives the tie bar  126  and the first link  140  connected thereto away from the actuator  26 . Movement of the tie bar  126  also moves the second blade  24  connected thereto away from the first blade  22 . This causes the center link  166  to rotate in a counterclockwise direction about the pivot pin  184  causing the second link  200  to move towards the actuator  26 . The second link  200  pulls the first carriage  100  and hence, the first blade  22  connected thereto away from the second blade  24  as the second blade  24  likewise moves away from the first blade  22 . When the rod  132  is fully extended, the blades  22 ,  24  are in their fully open position (as viewed in FIG. 5A) and the linkage assembly  28  is in its folded or retracted position. 
     Desirably, the linkage assembly  28  permits a single actuator  26  to move the first and second blades  22 ,  24  in opposed directions of the same stroke and speed, and in a very controlled manner to accurately and repeatedly engage the first and second blades  22 ,  24  with the flash  16  on the bottle  12 . Also, the actuator  26  and linkage assembly  28  preferably drive the blades  22 ,  24  to an intermediate or bottle receiving position between the fully open and fully closed positions as best shown in FIG.  1 . In this position, a molded bottle  12  can be received directly on the blades  22 ,  24  with a tail of flash  16  to be removed extending down between the blades  22 ,  24 . In contrast, in the fully open position of the blades  22 ,  24 , a bottle  12  may pass directly between the blades  22 ,  24 . This is desirable to permit a bottle  12  to be rejected for quality control or other reasons. 
     OPERATION 
     In a rotary blow molding machine  10  for forming plastic bottles  12 , after a bottle  12  is formed in a mold of the machine, a take out arm  40  is indexed into position adjacent to the mold and is driven to its extended position to insert its take out pin  44  into the bottle mouth  50  or opening of the bottle  12  while the bottle  12  is still in the mold (not shown). The take out pin  44  is expanded radially outwardly to engage and retain the bottle  12  on the takeout pin  44 , and the take out arm  40  is retracted to remove the bottle  12  from the mold. The take out wheel  38  is indexed to position the take out arm  40  with the bottle  12  thereon directly above the first and second blades  22 ,  24 . The take out arm  40  is then extended to dispose the bottle  12  on the first and second blades  22 ,  24  which are in their intermediate or bottle receiving position, shown generally in FIG.  1 . The pusher nest  30  and transport guide  32  are advanced towards each other by their respective actuators  64 ,  74 , until they engage and hold the bottle  12  in an upright position. The bumpers  72 ,  90  of the pusher nest  30  and transport guide  32 , respectively, meet to prevent these mechanisms from collapsing or placing undue force on the bottle  12 . 
     Next, to remove the bottle  12  from the take out pin  44 , the actuator  52  advances the stripper fork  58  until the times  60  are on opposed sides of the bottle neck  62 . The take out pin  44  is contracted and the take out arm  40  is retracted to withdraw the takeout pin  44  from the bottle  12 . Should the bottle  12  adhere to the take out pin  44 , the stripper fork  58  will knock the bottle  12  off of the take out pin  44  to ensure separation of the bottle from the pin  44 . 
     With the bottle  12  positioned on the blades  22 ,  24  the flash trimming assembly  20  is driven by the actuator  26  so that the blades  22 , 24  move simultaneously towards each other in opposed directions until they engage the bottle flash  16  in their fully closed position. With the bottle flash  16  engaged on opposed sides by the first and second blades  22 ,  24  the actuator  64  advances the pusher nest  30  which drives the transport guide  32  via the engaged bumpers  72 ,  90  to push the bottle  12  from the first and second blades  22 ,  24  onto the conveyor  33  without crushing or collapsing the bottle  12 . The bottle flash  16  remains between the first and second blades  22 ,  24  and thus is separated from the bottle  12  and may be reclaimed and recycled. 
     The stripper assembly  36  and pusher nest assembly  30  return to their initial, retracted positions to begin another cycle. The flash trimming assembly  20  returns to its intermediate or bottle receiving position as shown in FIG. 1 to receive a subsequent bottle  12  to be processed. Desirably, a bottle  12  may be rejected or scrapped before the flash  16  on it is removed by moving the blades  22 ,  24  to their fully open position shown in FIG. 5A so that a bottle  12  may pass between them to be removed from the processing cycle. For example, at the start of a production run, the initial bottles  12  formed may not meet desired specifications and so, they may be rejected before any flash  16  is removed by passing these bottles between the fully opened blades  22 ,  24 . After a desired time or number of bottles have been rejected, the blades  22 ,  24  are moved to their intermediate or bottle receiving position to conduct the flash removal operation on subsequent bottles.