Abstract:
A system and method for continuous automated production of insert pieces and insert injection molded parts has insert material supply reels loaded with a flexible insert material which is fed into an insert cutter and feeder assembly. The insert material supply reels supply large quantities of insert material ready for fabrication into insert pieces for direct insertion into an injection mold. The insert cutter and feeder assembly has one or more tracks along which the insert material is guided by unit-directional rollers to a cutter which severs insert pieces from the continuous strand of insert material. The continuously produced insert pieces are inserted into injection mold cavities by various inserted/pusher mechanisms between injection molding cycles. A control system synchronizes the cutting and feeding of insert pieces with the molding cycle for continuous production of insert molded parts.

Description:
FIELD OF THE INVENTION 
     The present invention pertains generally to manufacture of parts by injection molding and, more particularly, to continuous molding of parts which have a separate insert piece which is inserted into a mold cavity prior to injecting the mold. 
     BACKGROUND OF THE INVENTION 
     Insert molding, as referred to herein, generally refers to the practice of molding a material about or around a separate piece, so that the molded material is integral with, bonded to, or partially or completely surrounds or encapsulates the separate insert piece in a finished part. To accomplish this, the insert piece must be inserted into the cavity of a mold, such as a plastic injection mold or casting mold, prior to injecting the mold with a molding material. A new insert piece must be inserted into the mold at the start of each mold cycle. Typically, the insert is positioned in the mold by hand or by robot, during the period when the mold is opened between injection/compression cycles. Of course, this additional operation per part greatly reduces the rate of mass production. 
     In continuous production of insert molded parts, the insert pieces must be arranged for rapid and continuous insertion into a mold. Small insert pieces may be arranged upon racks, or stacked in a magazine which feeds into the mold cavity. The insert piece supply system be constantly re-stocked and monitored throughout the production process. Typically, the insert pieces are manufactured in an operation completely separate from the molding operation, and then arranged for continuous insert molding production. This amounts to two different manufacturing operations in order to produce a single finished part. 
     SUMMARY OF THE INVENTION 
     The present invention provides an automated system for the continuous production of plastic injection molded parts which include an insert part cut from a continuous feed of insert stock material. In accordance with one general aspect of the invention, there is provided a system for automated molding of parts around insert pieces which are continuously fed, cut and inserted into a die in an injection molding machine. In accordance with a more particular aspect of the invention, there is provided a system for continuous production of insert molded parts, wherein each part has a flexible insert piece cut from a continuous strand and fed into an injection molding machine, and wherein the part is formed by injection of plastic molding material around the insert piece. The continuous cutting and feeding of the insert pieces from a supply source enables uninterrupted production of insert molded parts, eliminating many of the intermediate steps in prior production processes. 
     In one particular application of the invention, there is provided one or more reels for spooling up of a continuous strand of material from which insert pieces are cut for insertion into an injection mold. In a preferred embodiment, the reel has multiple spool channels for receiving multiple strands of insert material, for simultaneous feeding into multiple mold cavities. The reels are rotationally mounted and driven for continuous feed according to a rate of injection mold operation. A cutting and feeding assembly is adapted for operative association with an injection molding machine, and operates to cut insert pieces from the reel-fed supply of material, and insert the pieces into an injection mold. In one particular embodiment of the insert piece cutting and feeding assembly, the insert material is fed through roller blocks which grip the material and hold it in position for severing an insert piece by a cutting station. The severed insert piece is then advanced through the feeder assembly and inserted into a mold cavity. The mold is then closed about the insert, and molding material is injected and molded around the insert to form an insert molded part. 
     These and other aspects of the invention are herein described in detail with reference to the accompanying Figures. 
    
    
     DESCRIPTION OF THE FIGURES 
     FIG. 1 is a schematic elevation of an automated system for molding of articles with insert pieces; 
     FIG. 2 is a side elevation view of an insert material reel of the present invention; 
     FIG. 3 is an end elevation view of two insert material reels mounted in tandem; 
     FIG. 4 is an elevation view of a portion of an insert piece cutting and feeding assembly of the present invention, taken in the direction of the arrows  4 — 4  in FIG. 1; 
     FIG. 5 is a top view of a portion of an insert piece cutting and feeding assembly of the present invention; 
     FIG. 6 is partial cross-sectional view of a portion of an insert piece cutting and feeding assembly, taken in the direction of the arrows  6 — 6  in FIG. 5; 
     FIG. 7 is a partial cross-sectional view of a portion of an insert piece cutting and feeding assembly, taken in the direction of the arrows  7 — 7  in FIG. 5; 
     FIG. 8 is a partial cross-sectional view of a portion of an insert piece cutting and feeding assembly of the present invention, and 
     FIGS. 9,  10  and  11  are perspective, plan and elevation views, respectively, of an insert molded product which can be produced in accordance with the machinery and methods of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention provides a system and method for automated continuous production of insert molded articles, i.e., articles which are injection molded about another piece inserted into an injection mold. FIGS. 9-11 are representative of only one type of insert molded part which can be manufactured in accordance with the invention. It is described for illustrative purposes only, and does not limit the scope or applicability of the invention. As shown in FIGS. 9-11, a molded article  100  has an insert piece  200 . Molded material  110  is molded around the insert piece  200 , to encapsulate the insert piece and form an integral multiple component part. The molded article  100  has appendages  120  which extend from a main body  130 , which surrounds the insert piece  200 . The body and appendages are molded out of any material which is suitable for injection molding, such as ABS or polypropylene. The insert piece  200  is in this example generally elongate and planar, and is dimensioned to extend the approximate length of the body  130 . The insert piece material may be virtually anything, but is in the described example and machinery generally flexible material which can be wound upon a reel, and which is able to be cut by shearing, chopping, sawing or other severing operations. The principles of the invention are not limited to any particular materials or forms of the molded material  110  and insert piece  200 . Also, the invention is not limited to the insert material being in spooled or wound form, but rather includes the continuous feed of insert material in any configuration. 
     As shown in FIG. 1, the invention includes an automated system, indicated overall at  10 , for manufacture of injection molded articles, of the type of FIGS. 9-11, which include insert pieces. The system  10  includes one or more reels  20  upon which a continuous strand of insert material  201 , such as steel, glass, plastic, fibers or plastic encapsulated fibers such as pultrusions, or any other suitable material with sufficient flexibility is spooled. The insert material  201  is fed from reel  20  into an insert piece cutter/feeder assembly, indicated generally at  30 , which is operatively associated with an injection molding machine, indicated generally at  60 , for insertion of insert pieces, cut from the continuous strand of insert material  201 , into one or more mold cavities in the injection molding machine. Each of the three main components of the system, the reel  20 , cutter/feeder assembly  30  and injection molding machine  60  are further described below. 
     As separately depicted in FIG.  2  and FIG. 3, the reel  20  is formed by major rings  21  arranged in parallel planes about a hub  22 . Spoke members  23  extend from hub  22  to rings  21 . As shown in FIG. 3, between rings  21  are a plurality of spacer rings  24  arranged in spaced apart parallel planes about hub  22 , and also supported by spoke members which extend from the hub. In the embodiment shown, five spacer rings  24  form six separate reel channels  25 , between the major rings  21  for spooling of six different feeds or continuous strands of insert material, flexible enough to be wound about hub  22 . The reel  20  can be dimensioned according to the type and amount of insert material to be spooled. In one embodiment, for example, the approximate diameter of the major rings  21  may be as large as seven to eight feet, and the diameter of the hub  22  approximately two to three feet. Of course, the reel  20  can be made larger or smaller. Different numbers of spacer rings can be used, or no spacer rings at all. 
     As further shown in FIG.  2  and FIG. 3, the major rings  21  of the reel  20  are mounted upon rollers  29 , one or more of which are rotationally driven by motors  26  and belts  27 , in order to spool material on to the reel in preparation for production, and to spool material off of the reel at a rate which corresponds to the rate of injection molding, as further described below. The rollers  29  and motors  26  are mounted upon a support frame  28 , which can be positioned proximate to an injection molding machine as further described. The low profile of the frame  28  as shown is advantageous for loading and unloading of the reels. By mounting two reels in tandem, as shown in FIG. 3, production does not have to be interrupted during a reel change. 
     The continuous strands of insert material  201  are fed from the reels  20  into an insert piece cutter/feeder assembly, indicated generally at  30  in FIG. 1, and further illustrated in FIGS. 4-8. The insert piece cutter/feeder assembly  30  includes a frame  31  which can be separately supported or attached directly to a molding machine  60 , or to a mold within the molding machine. The frame  31  supports one or more tracks  32  along which strands of the insert material  201  are guided toward the injection molding machine  60 . As further shown in FIG.  4  and FIG. 5, on each track  32  is mounted a first roller block  34 , and a second roller block  35 . The roller blocks each include one or more sets of vertically opposed upper and lower rollers  36 . The upper or lower rollers are mounted in spring bias against the opposing rollers to exert a variable compression force against material positioned between the rollers. As shown in FIG. 4, the top rollers  36  may be configured with flanges  37  which bear against the opposing lower rollers, and whereby rotation of the top rollers drives opposite rotation of the lower rollers. The flanges  37  also function to keep the insert material in alignment with the contact surfaces of the rollers. 
     The roller axes  38  are ratchet mounted for rotation in only one direction, to allow the insert material to pass through the first roller block  34 , and to prevent withdrawal of the insert material from the second roller block  35 . As shown in FIG. 5, the first roller block  34  is actuated, by linear actuator  33 , to reciprocate along track  32 , toward and away from roller block  35 . As roller block  34  travels to the left over the insert material, the upper rollers  36  rotate counterclockwise while the opposing lower rollers rotate clockwise. This counter, unidirectional rotation is induced by frictional contact of the insert material traveling between the upper and lower rollers. When the first roller block  34  then reciprocates to travel to the right (in FIG.  4 ), the upper and lower rollers  36  lock up, binding the insert material between them and advancing the insert material along the track  32  toward and into the second roller block  35 . In the second roller block  35  the rollers similarly rotate unidirectionally, with the upper rollers rotating counterclockwise and the lower rollers rotating clockwise. The frictional gripping force of the upper and lower rollers of the second roller block prevent the insert material from retracting from the second roller block  35  (to the left in FIG. 4) when the first roller block  34  reciprocates back to the left. 
     Once the insert material has passed through the first and second roller blocks  34  and  35 , it then passes through a cutting station, indicated generally at  40  in FIGS. 1,  5  and  6 . The cutting station  40  includes a fixed cutting edge  41  mounted on the track  32 , and a moving cutting blade  42  which travels vertically to shear the material against the fixed cutting edge  41 , shearing off or otherwise forming an insert piece  200  from the strand of insert material to a desired length for insertion into the cavity of an injection mold. 
     As shown in FIG. 5, once the insert piece  200  is sheared off from the strand of insert material, it is translated laterally by an actuator  43  (also referred to as a “shuttler”) into a trough  44  within track  32 . In the particular embodiment shown, linear actuator  33  is connected to the first roller block  34 , through a pusher block  46 . As shown in FIGS. 7 and 8, upper and lower insert piece pushers  50  and  51  extend from block  46  toward trough  44 . When actuator  33  advances the first roller block  34  and pusher block  46  toward the second roller block  35  (to the phantom position shown in FIG. 4 ), the upper pusher  50  advances the insert piece  200  from trough  44  into a transfer station  55 . When the pusher block  46  is advanced again (toward the second roller block  35  (to the phantom position shown in FIG.  4 ), the lower insert piece pusher  51  linearly advances the insert piece from the transfer station  55  into a mold cavity  61  of an injection mold. The pushers are then retracted for the next cycle, whereupon the mold is closed about the insert piece, and molding material is injected about the insert piece to form an insert molded part. 
     The described system thus provides continuous production of insert molded parts, with a large continuous supply of insert material which does not have to be pre-manufactured or divided into individual parts. The system is applicable to any type of mold wherein a suitable entry port into the mold cavity can be made. In the described example, the inserts  200  slide into the mold cavity through a side entry configured to the cross-section of the insert. Separate reel and cutter/feeder assemblies can be arranged on opposing sides of a multiple cavity mold, so that inserts are simultaneously fed into both sides of the mold. Alternatively, the inserts can be simply positioned between the mold halves when the mold is open and otherwise held in place until the mold is closed. 
     The invention also includes a control system for controlling operation of the insert piece material stock supply, and the insert piece cutting and feeding assembly in synchronization with the operation of an injection molding machine. For example, a machine control system, such as a statistical process controller (such as manufactured by the Allen-Bradley Company) or as supplied with an injection molding machine, is connected to the drive mechanism of the insert piece material stock reel(s) and to the insert piece cutting and feeding assembly. In general, the control system is programmed to supply insert pieces to the mold according t the molding cycle. For example, if the mold opens every fifteen seconds and a newly molded part is removed or ejected, another insert piece is supplied to the mold shortly thereafter, whereupon the mold closed to form the next part. While the mold is closed, the insert piece for the next part is cut and prepared or positioned for insertion into the mold. The rate of advancement of the insert material supply reel(s) is set and controlled according to the mold cycle, and the corresponding rate of operation of the insert cutting and feeding assembly. The invention is thus adaptable to any type and speed molding operation. In many applications, the controller for that injection molding machine can be modified or programmed to control the synchronous operation of the insert piece cutting and feeding assembly. 
     Although the invention has been described with reference to certain preferred and alternate embodiments, the concepts and principles of the invention are not limited to these specific arrangements. For example, other types of insert material, in forms other than spooled reels, may be used. Also, the insert piece cutting and feeding assembly may be used in connection with any type of molding, forming, stamping, cutting or fastening machine, and with different types of molds or jigs or dies, including multiple cavity molds with multiple mold plates.