Combined mold carrier and linkage apparatus

Abstract: An injection molding machine (11) having a plurality of axially arranged mold stations (A,B,C,D) including structure for supporting sets of mold plates (19,21;31,32;36,37) and a mechanism for opening, closing and overstroking mold plates.

Description: BACKGROUND OF THE INVENTION The present invention relates to an injection molding machine according to the prior art portion of claim 1 and relates, in particular, to machines having a plurality of axially arranged mold stations each station having cooperating mold plates defining mold cavities in well known fashion. This mold arrangement is known in the art as a stack mold. In prior art machines a plurality of sets of mold plates, one set of mold plates for each mold station, are operated, open and closed, by a variety of mechanisms many of which are complicated and obstruct access for servicing molds at the various mold stations. Typical prior art mold operating mechanisms are shown in FIG. 2 of U.S. Patent No. 3,659,997 and FIG. 1 of U.S. Patent No. 4,207,051. An injection molding machine of the type indicated in the preamble of claim 1 is disclosed in FR-A-2 145 610. In prior art arrangements there are numerous problems relating to alignment, support and precise movement of mold plates in order to achieve the highest quality molded product with minimum wear and tear of the mechanisms utilized to open and close the mold cavity at the various mold stations. One other problem is the lack of adequate access in the open mold condition to service the molds and mold plates and to replace molds without having to dismantle the molding machine. That is, many prior art units support the mold plates on the machine tie rods which involves a cumbersome, time consuming, laborious task when one wishes to replace molds. Such a step frequently involves removal of tie rods. Furthermore, it is desirable to provide a mold actuating mechanism that moves the various sets of mold plates from the open and closed positions so that all mold stations open and close simultaneously and precisely during the course of a continuous molding cycle. In addition it is desirable to provide a mechanism that one can "overstroke" readily to increase access to service and replace molds and/or mold plates without major disassembly of the molding machine. The term overstroke is intended to mean intentional opening of the various mold stations a distance beyond the normal open stroke distance of the normal cycle of operation. A set of mold plates in the disclosed embodiment of the present invention includes mold plates, per se, and support plates to which the mold plates are attached, sometimes referred to collectively as a "set of plates". OBJECTS OF THE INVENTION A principal feature of the present invention is the provision of a novel means for supporting a stack mold having a plurality of molding stations. A further important feature of the invention is the provision of a simple, durable mechanism for opening and closing all molds at a plurality of molding stations simultaneously, precisely and with uniform stroke. A further feature is the provision of mold support means and mold actuating means which facilitates rapid, and convenient installation and removal of elements of multilevel molds (a plurality of axially arranged molding stations, i.e. stack mold) with minimum dismantling of molding machine. A still further feature of the invention is the provision of a novel method of opening and closing a plurality of axially arranged mold stations simultaneously and precisely. SUMMARY OF THE INVENTION The present embodiment of the invention includes a basic machine frame including the classic tie bars which extend, in upper and lower pairs, from a fixed platen at one end to the machine frame at the opposite end of the tie bars. The injection molding machine of the present invention is characterized by the features of claim 1, preferred embodiments are subject of dependent claims. A movable platen reciprocates along the upper and lower pairs of tie bars. A central set of mold plates are received in a support member which, in turn, is supported by and is movable along the upper and lower tiers of tie bars. The central set of mold plates are readily removable in that they may be lifted vertically free of the support member. Correspondingly new or replacement central plates are installed by merely lowering the plates until they bottom on the support member. A primary crank mechanism is pivotally connected to the central set of mold plates via the support member and is linked pivotally at opposed ends to the movable platen and to the fixed platen. The connection to the platens is accomplished by pivotally mounted links. The primary crank mechanism straddles the injection molding machine and exists in the form of a pair of primary cranks which are spaced outwardly of the tie bars. To and fro motion of the movable platen actuates the primary crank mechanism maintaining the central mold plates equidistant from the fixed and movable platens as the molding machine cycles from open to closed positions. A secondary crank mechanism, comprising in the disclosed embodiment, opposed pairs of smaller cranks supported pivotally and individually by sets of mold plates which are positioned on opposite sides of the central set. One end of the secondary cranks are linked pivotally to opposite sides of the central plates and the opposite end of a first pair of secondary cranks are linked pivotally to the movable platen while the opposite end of a second pair of secondary cranks are linked pivotally to the fixed platen. The secondary cranks are disposed inwardly of the machine tie bars in opposed pairs. Thus motion of the movable platen drives the primary cranks and in so doing drives the secondary cranks so that the primary and secondary cranks provide the motion to open and close the mold stations in a precise and simultaneous manner which will be more apparent as this specification proceeds. While the disclosed embodiment of the invention discloses one pair of primary cranks and two pairs of secondary cranks operating and providing motion for four (4) mold stations it is entirely within the spirit and scope of the invention that the described crank arrangement be duplicated axially to operate many axially arranged mold stations. Sets of mold plates (second and third sets) on opposite sides of the central set of mold plates (first set) are supported by pairs of laterally spaced pins projecting from the mold plates which are fastened to the movable and fixed platens, respectively. The pairs of pins are offset vertically so as to avoid interference as the mold stations open and close. The pins are received in sleeve bearings or bushings formed in the upper ends of the second and third sets of mold plates. In normal mold open and close positions the pins are also received in sleeve bearing formed in the central set of mold plates which provides support for the terminal ends of the pins. When the mold stations are overstroked i.e., moved to a mold open position beyond the normal open position to provide operator increased access for servicing the molds, the support pins withdraw from the bushings of the central set of mold plates. To compensate for the loss of support for the free or terminal ends of the pins and loss of support for the second and third sets of mold plates, auxiliary support means are provided in the form of "outriggers" extending from the second and third sets of mold plates. The outriggers are bearing means or shoes which bear upon and move along the upper pair of tie rods thus augmenting pin support in the overstroked condition. Other features and advantages of the present invention will become more apparent from an examination of succeeding specification when read in conjunction with the appended drawings; in which: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view of a portion of an injection molding machine showing a multi-level mold (axially arranged mold stations) in the open mold position; Figure 2 is a view similar to the showing of Figure 1 illustrating the closed mold position; Figure 3 is a schematic illustration of the overstroked position; Figure 4 is a vertical section of Figure 1 in the plane of the line 4-4 as viewed in the direction of the arrows showing a mold face with the primary crank means removed; Figure 5 is a vertical section of Figure 1 in the plane of the line 5-5 as viewed in the direction of the arrows with the primary crank means removed; Figure 6 is a top plan view of the various sets of mold plates showing, schematically, the mold stations in the open mold condition as well as the disposition of the primary and secondary crank means. Guide pins for the several sets of mold plates are not shown for purposes of clarity; Figure 7 shows, schematically, an alternative mechanism for opening and closing molds; the mold stations A, B, C and D are shown in the closed condition; Figure 8 is similar to Figure 7 showing the mold stations in the open condition; and Figures 9 and 10 show an alternate embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS AND METHODS Referring in detail to the drawings, in particular Figures 1, 2 4, and 6, the reference numeral 11 indicates, generally, a portion of an injection molding machine comprising a plurality of mold stations A, B, C and D, all in the open mold position, disposed between a fixed platen 12 and a movable platen 13 with a pair of upper tie bars 14 and 16 and a pair of lower tie bars 17 and 18. Mold stations A and B are supplied with moldable material via supply conduit S and mold stations C and D are supplied via conduit S'. The tie bars are secured at one end to fixed platen 12 and at the opposite end to a machine frame member, not shown. In classical fashion the movable platen 13 is supported by and is moved, to and fro, along the tie bars to open and close the mold stations by conventional drive means such as a hydraulic ram, not shown. A central set of mold support plates 19 and 21 carrying mold plates 25 and 30 are received in and supported by support member 22 in turn, carried movably by the lower pair of tie bars 17 and 18 and stabilized by engagement with an upper pair of the bars 14 and 16. The plates 19 and 21 and all associated mold plates comprising mold stations A-D are removable as an assembly by lifting the assembly vertically free of the support member 22. Note that the support member 22 includes a pair of shoes or bearings 50 which engage and ride along upper tie bars 14 and 16 and a pair of shoes 55 which engage and ride along the lower tie bars 17 and 18 thereby guiding and stabilizing support member 22. As is most apparent in Figure 1 the upper end of the plates 19 and 21 are formed with primary and secondary sleeve bearings or bushings 23 and 24 operable to receive ends of guide or support pins 26 and 27 respectively. That is, a pair of pins 26-26 are received in a pair of primary bushings 23-23 and a pair of pins 27-27 are received in the secondary bushings 24-24. Reference numerals are hyphenated in the drawings to indicate pairs. Opposite ends of the pairs of pins 26-26 and 27-27 are fastened to the movable platen 13 and the fixed platen 12 by means of plates 15 and 20, respectively. The reference numerals 28 and 29 denote pairs of clearance holes for the guide pins when the mold stations reach the closed position as is most apparent in Figure 2. A second set of plates 31 and 32, supporting mold plates 33 and 34, and a third set of plates 36 and 37 supporting mold plates 38 and 39 are also formed with pairs of primary and pairs of secondary bushings 41-41 and 42-42 respectively. That is, the primary bushings 41-41 of the second set of plates 31 and 32 receive pins 26-26 to support the second set of plates while the pair of secondary bushings 42-42 provide additional support for the pair of pins 27-27 when the molds are in the closed position. Correspondingly the third set of plates 36 and 37 are supported by the engagement of the pair of pins 27-27 in the secondary bushings 42-42 while the primary bushing 41-41 of this set of plates provide additional support for the pins 26-26 as the mold stations close. The reference numeral 43 denotes the mold plate which cooperates with mold plate 33 while the reference numeral 44 denotes the mold plate which cooperates with mold plate 39. A pair of primary cranks 46 (only one shown in Figure 1) are mounted pivotally to the plate support member 22 on opposed sides of the member 22. Ends of the crank 46 are connected pivotally by means of pivot links 47 and 48 to movable platen 13 and fixed platen 12, respectively. Each of the second and third sets of plates (31 and 32 and 36 and 37) support pivotally pairs of secondary cranks 49 and 51 (only one crank of each pair shown in Figure 1). One end of the secondary cranks are connected by pivot links 52 and 53 to central plates 19 and 21 and at their opposite ends are connected to plates 15 and 20 respectively. Figure 3 shows the mold stations in the overstroked condition providing wide spacing between mold plates to facilitate servicing. Note that in the Figure 3 position of the mold stations the pins 26-26 and 27-27 have withdrawn from central plates 19 and 21 leaving the ends of the pins without the support normally provided by central plates. In order to compensate for this loss of support in the overstroked condition the second and third sets of mold plates are provided with outriggers or auxiliary bearings 54 and 56 as best seen in Figure 5. These bearings bear upon and move along the upper tier of tie bars 14 and 16. While these bearings are operative during the normal open and close cycling of the various mold stations their utility is especially important when the molds are overstroked. Note further that during the course of normal operation of the mold stations including overstroking the primary and secondary cranks and their connecting links operate with precision opening and closing all molds simultaneously and the central mold set remains equidistant from the movable and stationary plates at all times. Referring to Figure 7, an alternative mechanism for opening and closing the mold plates is shown schematically wherein fixed platen 120 and movable platen 130 straddle mold stations A, B, C and D, illustrated in the closed condition. A rack 61 (first rack) is fastened at one end to fixed platen 120 and the opposite end is supported and engaged by pinion 62 (first pinion) carried by movable platen 130. A primary rack 63 (second rack) is fastened at one end to a set of central mold plates (first set) via plate support member 220 and the opposite end is supported and engaged by pinion 64 (second pinion). Pinions 62 and 64 are keyed together so that they rotate in unison upon shaft 66 secured to movable platen 130. Secondary racks 67 and 68, at mold stations A and B, are fastened to mold plates 69 and 71, respectively, and engage pinion 72. Secondary racks 73 and 74 at mold stations C and D are fastened to mold plates 76 and 77, respectively and engage pinion 78. Pinions 72 and 78, mounted on mold plates 310 and 360, respectively are identical and operate in conjunction with their respective racks to open and close mold stations A, B, C and D in precise and simultaneous fashion during the molding cycle. That is, the opening and closing strokes of the molds at stations A, B, C, and D are identical and occur simultaneously. The relative mechanical advantage among the pinions 62,64 and identical pinions 72 and 78 is such that upon moving the movable platen 130 in an opening stroke (by well known means) to open all mold stations, platen 130 moves a distance x, central mold plates in members 220 move a distance x/2 and the mold plates 310 and 360 move a distance x/4 (all in the same direction) so that all mold stations open precisely and with a uniform opening dimension. It is to be understood that mold plates 69 and 77 are mounted upon opposed sides of member 220, plate 71 is mounted upon movable platen 130 and plate 76 is mounted upon fixed platen 120. Mold plates 69' and 71' are mounted upon opposed sides of plate 310 while mold plates 76' and 77' are mounted upon opposed sides of plate 360. The differential movement described above is achieved by selecting the diameter and therefore the peripheral measurement of the several pinions so as to generate the desired linear motion. Motion of the member 220 operates to open mold stations C and D in response to the action of racks 73 and 74 cooperating pinion 78. Figures 9 and 10 show an alternate embodiment of the present invention, with Figure 9 showing the mold closed position and Figure 10 showing the mold open position. In this embodiment, there are three mold support members 104A, 104B and 104C, with each mold support member supporting respective mold plates. The previous embodiment used only one such support located centrally on the mold, with support for the second and third sets of mold plates coming from guide or support pins through the top of the mold plates which remained engaged even when the mold was opened. The disadvantage of the previously described design is that the secondary mold linkages could further be improved to provide greater access to the open spaces between the mold portions when the mold is in the open position. The embodiment of Figures 9 and 10 does not use the long guide or support pins through the top of the mold which can bend or sag with heavy mold portions. Instead, the similar mold support members 104A, 104B and 104C each carry a portion of the mold assembly to locate and guide it during wide opening strokes, as clearly shown in Figures 9 and 10. The support members may run on precision alignment features of the molding apparatus, such as the tie bars or machine ways or the like. Separation between the mold portions is provided via linkages or secondary motion means 102 which are connected at one end to the respective mold support members and at the other end to the primary motion means 101. As the moving platen 105 is caused to move away from the stationary platen 106, link arms 103 insure that the center most portion of the mold remains equidistant between the two machine platens. Additionally, the secondary motion means 102 are caused to move since they are attached to the primary motion means 101. Secondary motion means 102 are designed and positioned such that they will maintain a equal spacing between the open mold portions as shown at Y in Figure 10. In the embodiment of Figures 9 and 10, the pivot point of secondary motion means 102 is halfway between the center pivot point of primary motion means 101 and its extreme pivot point with link arms 103. Additionally, secondary motion means 102 is half the length of link arm 103 and is pivotably attached to the respective mold support members 104B and 104C such that it runs parallel to link arm 103 at all times. This insures that the spacings Y will be equal through the entire mold open movement, if so desired. The advantage of this embodiment is the more accessible area between the mold open spacing and a simpler mold movement actuation device with the relatively simple movements of the primary and secondary motion means. It is anticipated that numerous variations and modifications may be derived without departing from the spirit and scope of the invention. For example, a variety of mechanisms may be devised to provide the motion for opening and closing the mold stations in precise fashion.

Claims: Injection molding machine including a first stationary platen assembly (12) and a second platen assembly (13) movable relative to said first platen assembly, a mold arrangement comprising a plurality of movable plates (19,21;31,32;36,37) defining a plurality of mold halves between cooperating sets of mold plates (25,30;33,34;38,39), said plurality of movable plates including at least one first plate and a first set of opposed mold halves mounted thereon, a primary motion means (46) connected to said stationary (12) and movable platen assemblies (13) and operative to move said first set of opposed mold halves, wherein said sets of mold plates are disposed axially to define a plurality of axially arranged mold stations (A,B,C,D) operable to open and close all of said axially arranged mold stations simultaneously during cyclic molding machine operation, characterized by at least a second set of opposed mold halves on one side of the first set of opposed mold halves and at least a third set of opposed mold halves on the opposite side of the first set of opposed mold halves, wherein said first plate is spaced between said second and third sets of opposed mold halves, a first secondary motion means (49) operative to move said second set of opposed mold halves, and a second secondary motion means (51) operative to move said third set of opposed mold halves, wherein said first secondary motion means (49) is on one side of the at least one first plate and the second secondary motion means (51) is on the opposed side of the at least one first plate, said first secondary motion means (49) and said second secondary motion means (51) being further connected so that movement of the primary motion means (46) is operative to move said first and second secondary motion means, and wherein said first and second secondary motion means are operative to move said second and third sets of opposed mold halves, respectively. Machine according to claim 1 wherein said secondary motion means ist further connected to said stationary and movable platens, respectively, and to said first set of plates. Machine according to claim 1 or 2 including a first support means (22) for receiving and supporting said first set of plates (19,21), said first support means being disposed between the primary motion means, and providing a carriage for said first set of plates. Machine according to one of the claims 1 to 3 including a second support means for receiving and supporting said second set of plates (31,32), said second support means being disposed between the secondary motion means and providing a carriage for the second set of plates, wherein the secondary motion means is further connected to said primary motion means and said secondary support means. Machine according to one of the claims 1 to 4 wherein the primary motion means defines an elongated arm, and link means connected to opposed ends of said arm, a first link means (47) connected to said movable platen (13) and a second link means (48) connected to said fixed platen (12). Machine according to one of the claims 1 to 5 wherein the primary motion means includes a pair of crank means (46) disposed on opposite sides of said plates, each crank means of said pair of crank means being positioned outwardly of said tie bars. Machine according to one of the claims 1 to 6 including a third set of plates (36,37), a second secondary motion means connected to said third set of plates. Machine according to claim 7 wherein the first secondary motion means and the second secondary motion means are connected to opposite sides of said first set of plates. Machine according to claim 7 wherein the first and second secondary motion means define elongated arms including link means joined to opposed ends of said arms, the link means of said first secondary motion means being connected to said movable platen and to said first set of plates, the link means of said second secondary motion means being connected to said fixed platen and to said first set of plates. Machine according to claim 7, including a second support means for supporting and guiding said second and third sets of plates. Machine according to claim 10 wherein the second support means includes opposed pairs of pin means extending from said platens, a first pair of pin means (26) being offset from a second set of pins (27 ) to provide pin means clearance as the mold stations open and close. Machine according to claim 11 wherein the second support means includes first bearing means (41) in said second and third plates for receiving said set of pins. Machine according to claim 12 wherein the pin means includes end portions opposite the respective platens and the first set of plates is formed with bearing means (23,24) for receiving and supporting said end portions. Machine according to claim 12 wherein the second and third sets of plates include second bearing means (42) engageable with the upper pair of tie bars to provide additional support for said second and third sets of plates. Machine according to claim 14 wherein the first and second bearing means (41,42) or the second and third sets of plates are disposed on opposite sides of said second and thirs sets of plates. Machine according to one of the claims 1 to 15 wherein the primary motion means comprises: rack means (61,63) and cooperating pinion means (62,64), a support member (220) for supporting said first set of plates (19,21), a first portion of the rack means (61) being secured to the fixed platen (120), a second portion of the rack means (63) being secured to said support member (220), said pinion means defining a plurality of pinions (62,64) fixed to said movable platen (130), and each rack position having a cooperating pinion individual thereto whereby motion of the movable platen is effective to move said first set of plates via motion of said support member.

Inventors: DI SIMONE JOHN, SCHAD ROBERT D, DI SIMONE, JOHN, SCHAD, ROBERT D.
Applicants: HUSKY INJECTION MOLDING, HUSKY INJECTION MOLDING SYSTEMS LTD.
Application year: 1995
Main classification: B29C45
IPC codes: B29C45