Actuator for controlling multiple injection molding valve pins

Abstract

A valve gate assembly having an actuator assembly configured to simultaneously control multiple valve pins to regulate the flow of liquid resin into a mold cavity of an injection molding machine is configured to allow for fast and easy simultaneous removal of the actuator assemblies from the pins by providing a valve plate having multiple slots or pockets for receiving and releasably retaining corresponding ones of the pins.

Description

[Technical field]

[0001] This application claims priority to U.S. Patent Application No. 16 / 579,093, filed Sep. 23, 2019, which is incorporated by reference in its entirety.

[0002] The present disclosure relates to injection molding apparatus, and more particularly to a valve gate assembly having an actuator that simultaneously controls the flow of liquid resin through two or more injection nozzles. [Background technology]

[0003] An injection molding apparatus having an actuator controlling the flow of liquid resin through two or more injection nozzles reduces the number of actuators required to control the flow of resin into multiple cavities defined in a mold or into multiple mold inlets to a single cavity, thus reducing both capital and operating costs, while allowing for closer nozzle centers. A fastening means is provided for connecting each valve pin to a valve pin carrier that is coupled to a cylinder rod of the actuator. Maintenance requires disassembly of each individual connection between the valve pin carrier and the valve pin, and the valve pins are usually captured or stuck in place by solidified resin. Conventional disassembly involves extended inspection and maintenance time and reduced production time. It is an object of the present disclosure to provide a valve gate assembly that reduces inspection and maintenance time and increases production time. Summary of the Invention

[0004] The present disclosure is directed to a valve gate assembly, and an actuator assembly, which provides a quick disconnect and quick assembly arrangement that allows for quick and easy removal of the actuator assembly from and assembly onto a plurality of valve pins, thereby reducing the time required to service the valve gate assembly or a molding apparatus with which the valve gate assembly is associated and increasing available production time.

[0005] The valve gate assembly includes a manifold defining a number of channels for delivering resin to a number of injection nozzles, a number of nozzles associated with corresponding cavities or cavities, a number of valve pins that move linearly within the axial bores of the associated nozzles to control the flow of resin through the gates of the nozzles, one or several actuators having linearly movable rods, and a valve pin plate including valve pin couplers connected to the rods and associated with each of the plurality of valve pins.

[0006] In some embodiments, the valve pin coupler includes a valve pin head receiving section and a valve pin head retaining section. The valve pin head retaining section retains the pin so that it moves with linear movement of the valve pin plate and actuator rod, and the valve pin receiving section allows for insertion and removal of the valve pin head. Multiple valve pin couplers are oriented relative to each other such that linear movement of the plate relative to the valve pin moves all of the pins simultaneously between the associated retaining and receiving sections. A lock, such as a set screw, may retain the valve pin plate relative to the valve pin and actuator. [Brief description of the drawings]

[0007] [Figure 1]FIG. 1 is a cross-sectional view of an injection molding apparatus incorporating the valve gate assembly and actuator assembly of the present disclosure. [Diagram 2] FIG. 2 is a perspective view of the valve gate assembly shown in FIG. [Diagram 3] FIG. 3 is a perspective view of the actuator assembly shown in FIGS. 1 and 2, partially cut away to show internal detail. [Figure 4] 4 is a cross-sectional view of the actuator assembly of FIG. 3 at a stage during disassembly. [Diagram 5] 4 is a cross-sectional view of the actuator assembly of FIG. 3 at a stage during disassembly. [Figure 6] 4 is a cross-sectional view of the actuator assembly of FIG. 3 at a stage during disassembly. [Figure 7] 4 is a cross-sectional view of the actuator assembly of FIG. 3 at a stage during disassembly. [Figure 8] FIG. 4 is a top view of the valve pin plate from the actuator assembly of FIG. [Figure 9] FIG. 9 is an enlarged top view of a pin retaining pocket defined in the valve pin plate of FIG. [Figure 10] FIG. 13 is a perspective view of an alternative embodiment in which the actuator can be disengaged from multiple valve pins by rotational movement. [Figure 11A] FIG. 13 is a perspective view of an alternative valve plate configuration to facilitate removal of the actuator assembly from the hot runner system without removing the valve pin from the manifold. [Figure 11B] FIG. 13 is a perspective view of an alternative valve plate configuration to facilitate removal of the actuator assembly from the hot runner system without removing the valve pin from the manifold. [Figure 11C] FIG. 13 is a perspective view of an alternative valve plate configuration to facilitate removal of the actuator assembly from the hot runner system without removing the valve pin from the manifold. [Figure 11D]FIG. 13 is a perspective view of an alternative valve plate configuration to facilitate removal of the actuator assembly from the hot runner system without removing the valve pin from the manifold. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A hot runner assembly 10 (shown in cross section in FIG. 1) for an injection molding apparatus includes a heatable manifold 12 having a plurality of passages that define a hot runner system that facilitates the flow of liquid resin (typically a thermoplastic polymeric composition) from an inlet channel 16 defined in a sprue busing 17 to a plurality of nozzles 20. The gating assembly shown includes a two-piece manifold 12 including an upper manifold section 12A and a lower manifold section 12B. Locating pins 13 may be used to ensure proper alignment of sections 12A and 12B. Manifold 12 is illustrative of a two-section manifold. However, the novel concepts of the present disclosure may be used with manifolds having a single section or any number of sections.

[0009] Each nozzle 20 has a cylindrical shape and includes a cylindrical bore 26 extending along the nozzle's cylindrical (or longitudinal) axis. One end of the cylindrical bore defines a gate 27. A valve pin 28 is centered within the cylindrical bore 26 and extends generally through the cylindrical bore from an actuator assembly 30 mounted on the manifold 12. The valve pin 28 also has a generally cylindrical shape (circular cross section) with a diameter less than the diameter of the cylindrical bore 26, and is generally centered within the bore 26 to define an annular space 32 between the wall of the bore 26 and the outer surface of the valve pin 28. The valve pin 28 is linearly movable along the longitudinal axis of the nozzle 20 between a first position (shown on the left side of FIG. 1) and a second position (shown on the right side of FIG. 1) in which a lower end of the valve pin is located within the gate 27 to prevent flow from the nozzle into a mold cavity 34 defined by a mold plate 36, and in the second position in which the lower end of the valve pin 28 is spaced from the gate. An upper end 38 of the nozzle 20 may be provided with external threads that engage internal threads in a nozzle receiving bore of the manifold 12 to facilitate disassembly of the assembly 10 for maintenance.

[0010] The illustrated assembly 10 employs hot runner technology in which the channels or other conduits used to carry liquid resin from the injection molding machine to the cavity 34 are continuously maintained at elevated temperatures during normal operation by a sprue heater 40, a manifold heater 42, and a nozzle heater 44. Heaters 40, 42, and 44 may be electrical resistance heaters.

[0011] The assembly 10 includes various support / alignment structures 46 , 48 , 50 , 52 to facilitate proper and stable alignment and spacing of the assembly 10 with the mid-plate 54 and top plate 56 .

[0012] 2, the assembly 10 includes a number of nozzles 20 associated with each of the actuator assemblies 30. In the embodiment shown, the flow of resin through three nozzles is regulated by each of two actuator assemblies 30. However, this example is illustrative and any number of nozzles may be associated with a single actuator assembly (e.g., two, three, or four nozzles may be controlled by a single actuator assembly).

[0013] The actuator assembly 30 and valve pin associated with the nozzle 20 are shown in Figure 3. The assembly 30 includes a cylinder actuator 60 (e.g., a hydraulic, electric, or pneumatic actuator) which may be a single-acting actuator, for example, where actuating fluid acts on only one side of a piston 62 and a mechanical load, such as a spring or compressed air, acts on the other side to cause controlled linear movement of a drive rod 64 attached to the piston 62. Alternatively, a double-acting actuator may be used, where actuating fluid acts on both sides of the piston to control the linear movement of the valve pin plate 66 and rod 64.

[0014] As shown in FIG. 3, the actuator assembly 30 includes a piston housing 63 in which a piston 62 is housed. The housing 63 is supported by a valve pin plate housing 65 in which a valve pin plate 66 is disposed. A circumferential ledge or shoulder 67 extends radially inward from an upper edge of the valve pin plate housing 65, and a vertical circumferential wall or collar 69 extends upward from the radially inner edge of the shoulder 67. The piston housing 63 is releasably supported on the valve pin plate housing 65 with a lower edge of the housing 63 supported on the shoulder 67 and with a lower end of a radially inwardly facing surface of the housing 63 abutting a radially outwardly facing surface of the collar 69. The housing 63 is releasably secured to the housing 65 by a plurality of screws 71 having thin or sharp ends that extend into the circumferential grooves 11 on the outwardly facing surface of the collar 69. The screws 71 pass through openings 73 in the piston housing 63.

[0015] The piston 62 is retained and reciprocates within a chamber 75 defined by the housing 63 and a cap 77 which is secured to the housing 63 by a snap ring 79. A pin seal retaining disk 90 is retained on the manifold 12 by bolts. The housing 65 is secured to the manifold by bolts 83. The pin seal retaining disk 90 also works with the pin seal 88 and the valve pin 28 to provide a seal against the flow of molten resin upward from the manifold.

[0016] A valve pin plate 66 is connected to the rod 64 and moves linearly therewith as determined by control of the actuator 60. The valve pin plate 66 includes a plurality of pockets 70 (FIGS. 8 and 9) for releasably receiving and retaining the valve pins 28. The pockets 70 are at least partially lipped, with the lip of each pocket configured to engage the underside of a head 72 (FIG. 4) of the valve pin 28. Each pocket 70 has a pin head receiving section 74 (FIGS. 8 and 9) configured to allow the head 72 to be inserted into the pocket, and a pin head retaining section 76 narrower than the pin head and having a ledge or lip 78 spaced to define a gap less than the diameter of the valve pin head 72 and at least equal to or slightly greater than the diameter of the stem portion 80 of the valve pin 28 such that when the pin head 72 is placed in the pin head retaining section 76 of the pocket 70, the valve pin 28 is retained within the pocket 70 and restricted from movement other than linearly with the valve pin plate 66. The pin head insertion section 76 is configured (shaped and dimensioned) such that the valve pin plate 66 can be disengaged (lifted) from the valve pin 28 when the pin head 72 is placed in the pin head retaining section.

[0017] FIG. 6 shows the actuator 30 moved linearly relative to the valve pin 28 to a position where the pin head 72 can pass through the pin head receiving section 72 to allow separation into components 99 as shown in FIG. 7.

[0018] Regardless of the number of pockets 70 for the pins 28, the pockets are oriented such that the plate 66 can be moved linearly or rotated (as shown in FIG. 10) to simultaneously position all of the pins 28 within the pin head retaining section 76 to facilitate simultaneous control of flow through each associated nozzle 20, or moved in the opposite direction to simultaneously position all of the pins 28 within the pin head insertion section 74 to facilitate separation of the actuator assembly 30 from the pins 28. To allow separation of the actuator assembly from the pins using linear motion, the linear portions of the pockets are arranged parallel. To allow separation using rotational motion, the lipped narrow portions of the pockets can be arranged along a circular path in the plane of the valve plate. A lock 91 is used to hold the position of the plate 66 relative to the pins 28 as they are retained within the pin head retaining section 76. The lock 91 shown is a socket head screw received in a threaded hole extending from a side edge of the plate 66' to the surface of the rod 64'. An opening 82 can be provided in the wall of the actuator assembly housing 84 to provide access to the head of a set screw. Other mechanical locks (such as spring-loaded pins or latch mechanisms) may be used in place of set screws.

[0019] In some alternative embodiments, pocket 70 may be replaced with a slot having a shape similar to pocket 70 ( FIG. 9 ), including a pin-receiving section through which pin head 72 can pass and a narrower pin-retaining section that prevents pin head 72 from passing through when the underside of pin head 72 engages the upper surface of plate 66.

[0020] In some embodiments, plate 66 may include an opening 86 (FIG. 8) that facilitates removal of plate 66 from rod 64 when lock 81 is disengaged (e.g., unsecured) from rod 64. Opening 86 includes a larger diameter section through which a flanged nut may be passed and a narrower section through which the flange on the nut may not be passed.

[0021] 4-7 illustrate removal of the actuator assembly 30 from the pins 28. In the fully assembled condition (FIGS. 1 and 4), the pins 28 are guided by pin seals 88 held in pin seal retaining disks 90 secured to the manifold 12, with the pin heads 72 held in the lipped portions of the pockets 70. Simultaneous removal of the actuator assemblies 30 from all associated valve pins 28 is accomplished by loosening (e.g., unscrewing) the locks 81 as shown in FIG. 5, linearly (or rotationally) moving the actuator assemblies from an orientation in which the pin heads 72 are positioned in the retaining section 76 to an orientation in which the pin heads 72 are positioned in the insertion / extraction section 74 of the pockets 70 (as shown in FIG. 6), and separating the actuator assemblies from the pins (as shown in FIG. 7). Installation is accomplished by reversing the removal steps. This arrangement significantly simplifies separation of the actuator assemblies from multiple pins. Another advantage is that because the valve pins remain with the manifold or hot runner assembly and are instead separate from the actuator assembly, the valve pins do not need to have their position adjusted every time the system is serviced, thus further reducing labor and production interruptions.

[0022] In an alternative embodiment shown in FIG. 10 that allows removal of the pin heads 72 from the pockets 70 by rotation of the valve pin plate 66' (indicated by arrow 2), a U-shaped retaining clip 85 securable to the plate 66' by bolts 87 secures the plate 66' to the piston rod 64'. A screw 91 extends radially through the valve pin plate into the narrower portion of the pocket to prevent rotation of the plate 66' relative to the pin and pin seal retaining disk 90 during normal operation of the hot runner assembly 10. The actuator assembly is removed, leaving the pins 28 in the manifold, by first removing or loosening the screw 91 (indicated by arrow 1 in FIG. 10), then rotating the actuator assembly in the direction indicated by arrow 2 in FIG. 10, and finally lifting the actuator as indicated by arrow 3 in FIG. 10.

[0023] As shown in FIG. 5, a screw 81 extends through a threaded hole from one side of the plate 66 to the piston rod 64. When the radially inner end of the screw 81 is engaged with the rod 64, the pin head 72 of the pin 28 is locked in place within the pin head retaining section 76 of the pocket 70 for normal operation of the hot runner assembly 10. When servicing the actuator, the screw 81 is rotated (e.g., counterclockwise) to pull the inwardly facing end of the screw 81 away from the rod 64. A screw access opening 82 through the housing 65 may be configured such that when the head of the screw 81 engages an inner surface of the housing 65 adjacent the opening 82, further rotation moves the disk 66 away from the head of the screw 81 and moves the pin head toward the pin head insertion (and removal) section 74 of the pocket 70 to allow removal of the actuator assembly.

[0024] 11A-11D show an alternative valve plate for facilitating removal of the actuator assembly 30 without removing the valve pin 28. The valve pin plate 166 includes multiple valve plate segments 166A, 166B, 166C bolted together, such as by bolts 97, having interfacing surfaces that together define a pin head retaining pocket 170. In the segmented valve pin plate shown, three segments define three interfacing surfaces, each interfacing surface configured to define a single pin head retaining pocket. Generally, it is preferred that each segment have two surfaces that interfacing with another segment to define a pin head retaining pocket. For example, four segments may be used to define four pin head retaining pockets on each of the four interfacing surfaces. However, other arrangements are possible, including a single interfacing surface that defines more than one pocket, or interfacing surfaces that do not define a pocket. An access opening 111 is provided for the bolt 97 to allow the spacing between the segments to be relaxed to provide the clearance needed to remove the actuator assembly without removing the pin 28.

[0025] Figure 11A shows the actuator assembly 30 and segmented valve pin plate 166 in a fully assembled condition for normal operation. Removal of the actuator for service is accomplished by first loosening the bolts 97 as shown by the arrows in Figure 11B. The actuator assembly 30 is then rotated slightly to separate the mutual contact surfaces of the segments as shown in Figure 11C, allowing the actuator assembly 30 to be lifted off the manifold and valve pin 28.

[0026] In some embodiments, the piston rod 89 may include a bore at its lower end adjacent the manifold to reduce conductive heat transfer from the manifold to the actuator through the rod 89.

[0027] According to the present disclosure, because the pins 28 remain with the manifold during removal of the actuator assembly 30, the pin positioning does not have to be adjusted to properly align the pin tips with the nozzle gates each time the actuator is removed for service, further reducing labor and downtime. The upper end of the piston rod 64 includes a hexagonal recess 93 (or other driver engagement feature) to facilitate pin alignment with a driver tool.

[0028] The above description is intended to be illustrative, not limiting. The scope of the invention should be determined with reference to the appended claims and their full scope of equivalents. It is anticipated and intended that further advances will occur in the art, and that the disclosed devices, kits, and methods will be incorporated into such future embodiments. Thus, the present invention is capable of modification and variation, and is limited only by the scope of the following claims.

Claims

1. 1. A valve gate assembly for an injection molding apparatus, comprising: a manifold having a plurality of passages for conveying liquid resin from the injection molding machine to the mold cavities; a plurality of nozzles attached to the manifold, each nozzle having a longitudinal axis and a cylindrical bore extending along the longitudinal axis for conveying liquid resin from the manifold to the mold cavity; a plurality of valve pins, each valve pin associated with a corresponding one of the nozzles and configured for linear movement within and along the cylindrical bore to control flow of liquid resin into the mold cavity, each valve pin having a head portion; an actuator having a linearly movable piston rod; a valve plate coupled to the actuator, the valve plate having a plurality of slots or pockets that receive and releasably retain corresponding ones of the plurality of head portions; a lock for engaging said piston rod and for holding said head portion in place within said slot or pocket, said lock being received through an edge of said valve plate; The valve gate assembly comprises:

2. 2. The assembly of claim 1, wherein the valve plate has a plurality of pockets including portions sized to allow insertion of the head portions and narrower portions for retaining the head portions.

3. 3. The assembly of claim 2, wherein the plurality of pockets are arranged with the narrow portions parallel such that the valve plate can be moved linearly to receive a plurality of the head portions and simultaneously position all of the head portions in the narrower portions of the pockets.

4. 2. The assembly of claim 1, wherein the valve plate is disposed within a valve plate housing, the valve plate housing being releasably coupled to an actuator housing including a reciprocable piston connected to the linearly moveable piston rod.

5. 5. The assembly of claim 4, wherein said valve plate housing has a circumferential ledge extending radially inward from an upper edge of a wall generally defining said valve plate housing, and a vertical circumferential wall extending upwardly from the radially inner edge of said circumferential ledge, whereby a piston housing is releasably supported on said valve plate housing with a lower edge of said piston housing supported on said circumferential ledge and with lower ends of radially inwardly facing surfaces of said pistons abutting a radially outwardly facing surface of said vertical circumferential wall.

6. 6. The assembly of claim 5, wherein said radially outwardly facing surface of said vertical circumferential wall has a circumferential groove, and said piston housing is releasably secured to said valve plate housing by threads which engage said circumferential groove.

7. 3. The assembly of claim 2, wherein the plurality of pockets are arranged such that the actuator and valve plate can receive a plurality of the head portions and can be rotated to simultaneously position all of the head portions in the narrower portions of the pockets.

8. 8. The assembly of claim 7, wherein a U-shaped retaining clip extends around said piston rod and is bolted to said valve plate, thereby securing said valve plate to said piston rod.

9. 8. The assembly of claim 7, wherein threads extend radially through said valve plate into said narrower portion of said pocket to prevent rotation of said valve plate relative to said valve pin.

10. 2. The assembly of claim 1, wherein said valve plate has an opening that facilitates removal of said valve plate from said piston rod when said lock is disengaged from said piston rod.

11. The assembly of claim 1 , wherein the lock is a screw received within a threaded hole extending through the edge of the valve plate.

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