Abstract:
Injection molded parts having bodies and lids connected by living hinges have the lids closed against the bodies during an opening sequence of mold plates. The lid closing mechanism is arranged in an intermediate plate disposed between a movable B plate and a fixed A plate. Movable and fixed cavities can meet within the intervening plate where a lid closer accomplishes lid closing as mold plates separate during mold opening. Accomplishing the lid closure during a mold opening sequence avoids any increase in the mold cycle time.

Description:
TECHNICAL FIELD 
     Closing living hinge lids of injection molded parts 
     BACKGROUND 
     Closing the lids of injection molded parts having bodies and lids connected by a living hinge has been problematic. Previous solutions have proposed that the lids be closed to the bodies after the mold opens. This involves reaching into the open mold space with something to move the lids closed, which adds costly seconds to the mold cycle time. Another solution has been to eject the parts into a machine that closes the lids outside the mold. This does not add to mold cycle time, but it adds expensive additional equipment for handling the ejected parts. Solutions have also included separately powered arms or devices to reach into the space available in an open mold to remove parts or close lids. This requires accurate timing and sensing of locations so that components of the mold do not crash into each other. 
     SUMMARY 
     The solution reached by this invention accomplishes lid closure during the opening movements of the mold plates without adding any time to the molding cycle. It also accomplishes lid closing by deriving the necessary movements from the moving mold plates themselves so that no additional power source or sensing systems are required. Since parts with closable lids are manufactured in huge numbers, accomplishing lid closure without increasing mold cycle time is highly valued. Also, accomplishing lid closure during opening movement of the mold plates, without requiring any additional machinery to close the lids of molded parts, saves much of the expense that previous solutions suffered. 
     The invention adds to a conventional mold an additional X plate between a fixed A plate and a movable B plate. The intervening X plate holds a lid closing assembly while allowing an A cavity and a B cavity to meet within the intervening X plate. Then as a support for the B plate begins an initial movement of an opening sequence, a core that forms a back or top side of the lid is removed from behind the lids. At the same time, a lid closer mounted in the intervening X plate is raised into the position behind the lids that the removed core previously occupied. In a subsequent move of opening mold plates, the B cavity and the X plate separate from the A cavity while the B cavity holds the bases of the molded parts. This movement pivots the lid closer through an arc that closes the lids as this mold opening sequence progresses. By the time that the mold plates are fully opened, the lids have been closed, and the parts are ejected without requiring any additional operation. Significantly, the lid closing process is accomplished within the normal opening time for the mold plates without adding any time to the molding cycle. When the mold recloses, the motions of all the moving components are reversed to bring the mold back to a closed relationship where the mold can be shot again. 
    
    
     
       DRAWINGS 
         FIG. 1  is an exploded schematic view of a preferred embodiment of mold plates capable of closing lids according to the invention. 
         FIG. 2  is a schematic view of a first opening split between the mold plates occurring during an initial opening movement of the mold parts. 
         FIG. 3  is a schematic view of a second split of the mold plates, with an intervening plate omitted for convenience of illustration. 
         FIG. 4  is a schematic view of a fully opened mold allowing ejection of the closed lid parts. 
         FIG. 5  is a schematic view of a cam mechanism for moving a lid closer into a position behind lids as a core is retracted from such a behind the lids position. 
         FIG. 6  is a schematic view showing movement of the cam system of  FIG. 5  to a position elevating a lid closer into a behind-the-lids position. 
         FIGS. 7 and 8  are similar schematic views of a rack and pinion arrangement for pivoting a lid closer from the starting position shown in  FIG. 7  through an arc to the lid closing position shown in  FIG. 8 . 
         FIGS. 9 and 10  are similar schematic views of a cam arrangement driving a rack that rotates the pinion of  FIGS. 7 and 8  to pivot a lid closer through a closing arc. 
         FIG. 11  schematically illustrates an aligned pair of molded parts with a lid closer behind the lids where it is ready to rotate the lids to a closed position when the illustrated pinions are rotated. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrations are schematic and eliminate many details necessary to a mold, but unnecessary for understanding the invention. Persons skilled in the art of injection molding will understand the details that must be added to make a mold successful and workable. The following description assumes up, down, forward, and back motions typical of an injection mold, but the reader should understand that molds and movements can be oriented in different ways and that these expressions are for convenience only. 
     Beginning with the exploded view of  FIG. 1 , a mold according to the invention includes a fixed A plate  20 , a movable B plate support  25 , a B plate  30 , and an intervening X plate  50 . The B plate includes a movable cavity  31  for a body portion  32  of a molded part that includes a lid  33  joined to base  32  by a living hinge  34 . A core  26  on the B support plate  25  serves as a portion of the B mold by forming the back or top side of lid  33 . The movable B cavity  31  meets the fixed A cavity  20  within the intervening X plate  50 , which carries a lid closer  70 . Ordinarily, a mold will have many A and B cavities arranged in rows and columns, but for simplicity of illustration the drawings show only a single row of 2 cavities. 
     When the exploded plates of  FIG. 1  are moved to closed positions, they abut each other, with the movable cavity  31  meeting the fixed cavity  21  within the intervening X plate  50 . In this position, lid closer  70  is located below lids  33  and is aligned with a space behind lids  33 . This space, in the closed mold position, is occupied by core  26 . The mold is then ready to be shot to produce bodies  32  with lids  33  and living hinges  34 . 
     After the cavities of a mold are shot, and the mold is ready to be opened, the initial movement in an opening sequence is movement of the B support plate away from the B plate, as illustrated in  FIG. 2 . The core  26  that is attached to the B support plate is thus withdrawn during the initial movement. This moves core  26  away from behind lids  33 , which are preferably arranged in rows within mold  10 . This initial opening movement also moves cam  27  with its fork-shaped angled slot  28 , as shown in  FIG. 1 . 
     Lid closer  70 , which has a bar shape that can extend along a row of lids  33 , as shown in  FIG. 11 , has end regions that engage slots  28  of a pair of cam forks  27 . The withdrawal of cam forks  27  with the movement of the B support plate  25  causes lid closer  70  to move up behind lids  33  into the space previously occupied by core  26 . 
     This upward movement of lid closer  70  is best shown in  FIGS. 5 and 6 . Before any movement of B support plate  25 , lid closer  70  is in the position shown in  FIG. 5  where its ends are near the closed end of slot  28 . Lid closer  70  is also constrained to move only vertically by a slot  63  in pivoter  60  that allows only vertical movement of lid closer  70 . Pivoter  60  is attached to a pinion  61  driven by a rack  62 . 
     As fork cam  27  withdraws with core  26  and B support plate  25 , lid closer  70  is forced upward by slot  28  and is allowed to move only vertically by pivoter slot  63  to the position shown in  FIG. 6 . When lid closer  70  reaches this position at the top of its vertical travel, it is held in place by detent  71 . By this time, forks  27  have moved clear of lid closer  70  and pivoter  60 . This positions lid closer  70  in the now empty space behind lids  33 , as shown in  FIG. 11 . Lid closer  70  is then in position to close and latch lids  33  against bodies  32 . 
     The next movement in the mold opening sequence moves intervening X plate  50  away from fixed A plate  20 . X plate  50  remains engaged with B plate  30 , which also holds the molded parts in its cavities  31 . The movement results in a gap where molded parts have departed from fixed cavity  21  in A plate  20 , as shown in  FIG. 3 , where X plate  50  has been removed to reveal the lid closing assembly. The moved X plate  50  reappears in  FIG. 4  where it is spaced from A plate  20 . Plate  50  is limited in opening travel by latch  51  that keeps plate  50  connected with A plate  20 , even when open, as shown in  FIG. 4 . 
     The opening movement of X plate  50  away from fixed A plate  20  as shown in  FIGS. 7 and 8 , operates a cam  55  that moves rack  62  upward as shown in  FIGS. 7 and 8 . Cam  55 , illustrated in  FIGS. 1 ,  9  and  10 , has a cam slot  56  that is followed by a bearing  57 . The raising of rack  62  rotates pinion  61  of pivoter  60 , which pivots with rotation of pinion  61 . This pivoting motion pivots lid closer  70  through an arc that closes and latches lids  33  against bodies  32 . This completes the lid closing operation during the opening movement sequence of the mold plates. 
     Since the lid closing is accomplished mechanically by movements derived from movements of mold plates themselves, timing of these motions is cam controlled so that components cannot crash into each other. The same movements that close the lids are reversed when the mold plates move back to a closed position for another shot. Completing lid closures within the normal opening sequence of the mold avoids additional cycle time so that the mold can operate at its top speed. One example of a 48-cavity mold operating according to the invention has saved 5 seconds of cycle time from 16 seconds used to close lids by a separate mechanism, compared with 11 seconds for closing the lids during the mold opening sequence as explained above. This results in enormous savings for parts that must be mass produced.