Patent Application
20080093773
These and other features and advantages of the present disclosure will be better understood by reading the following detailed description, taken together with the drawings wherein:
A sectional view of one embodiment of an injection nozzle assembly 10 is shown in
A stationary platen 30, which the nozzle assembly 10 extends through, may include a bushing plate 32, a retainer plate 34 and a cooling device 36. Attached to the cavity plate 24 may be an adapter plate 28 which engages a bushing 38 that surrounds at least a portion of the nozzle assembly 10. The bushing 38 may include seals 40 (such as metallic seals or the like) which engage the bushing plate 32.
The nozzle assembly 10 may comprise a nozzle body or tip 12 and a melt channel 16 which communicates molding material (for example, but not limited to, plastic) from the injection unit (not shown) to the mold cavity space 26 through a gate 42. According to one embodiment, the melt channel 16 may run the length of the nozzle assembly 10. Alternatively, the melt channel 16 may run only partially through the length of the nozzle assembly 10. The nozzle assembly 10 may also include one or more seals 44 to the bushing plate 32 to substantially prevent leakage of resin past the nozzle assembly 10.
The nozzle assembly 10 also includes a valve gating portion 93 for controlling the flow of resin into the mold cavity 26. According to one embodiment, the valve gating portion 93 may comprise a stationary valve stem 14 which may be at least partially located within the melt channel 16. The valve stem 14 may be secured (either removeably or permanently) to part of the nozzle assembly 10 (for example using a mounting flange 96) or may be formed as a unitary, single part of the nozzle assembly 10. While the valve stem 14 is shown substantially axially with the melt channel 16, other arrangements of the valve stem 14 with respect to the nozzle tip are possible and are considered within the scope of the present disclosure. For example, the valve stem 14 may be disposed at an angle with respect to the nozzle tip 12 and/or the melt channel 16.
According to one embodiment, a portion of the valve stem 14 may extend beyond the outlet of the melt channel 16. Alternatively, the valve stem 14 may be substantially entirely disposed within the melt channel 16. When the injection molding machine is in the closed position shown in
Referring now to
The amount that the gate 42 may be moved relative to the nozzle body 12 and valve stem 14 may be quite small, for instance, about 0.11 inches to about 0.22 inches, to open and close the gate. Of course, the gate 42 may be move more or less depending upon the intended application. According to one embodiment, this distance may be regulated by the mold clamping system.
Thus, rather than relying on pneumatic or hydraulic actuators to retract the valve stem 14 within the nozzle body 12 to allow material to flow through the gate 42, the injection mold 20 may be moved relative to the nozzle assembly 10. According to one embodiment, an actuator mechanism 200 of the injection molding machine may be coupled to the injection mold 20 and/or the bushing plate 32 to move the injection mold 20 relative to the nozzle assembly 10. The actuator mechanism 200 may also be used to separate the mold plates 22, 24 from the stationary platen along split line B to allow material to flow into the mold cavity space 26. Any modifications to the injection molding machine are considered within the knowledge of one of ordinary skill in the art in view of the present disclosure. Alternatively, a separate actuator mechanism 200 may be used to move the injection mold 20 relative to the nozzle assembly 10.
Put another way, the gate 42 may be moved relative to the injection nozzle 12 and valve stem 14 (which may both remain stationary) by the action of the machine open/close actuator. Since the valve stem 14 does not move relative to the nozzle body 12, the use of a separate mechanism for retracting the valve stem within the nozzle body can be eliminated. Additionally, since multiple nozzle assemblies 10 may be disposed within the bushing plate 32, the open/close actuator according to the present disclosure may be used to eliminate the need for individual valve stem actuators for each nozzle assembly 10. This improvement may be achieved even if an actuator is used that is separate from the open/close actuator.
For example, according to one embodiment the actuator mechanism 200 may include an actuator 300,
Those skilled in the art will recognize that a wide range of actuator mechanisms 200 may be used to move the gate 42 relative to then injection nozzle 12. For example, the actuator mechanisms 200 may include one or more springs (not shown) disposed between the adapter plate 28 and the bushing plate 32 which takes advantage of the injection machine clamping force in order to move the gate 42 relative to the injection nozzle 12. Alternatively, a camming device (such as, but not limited to, an offset cam bolt or the like) may be linked or otherwise coupled to the plates 20, 28, 32 to provide the necessary motion. The present disclosure is not limited to any specific embodiment for providing this motion unless specifically claimed as such.
According to one embodiment, the present disclosure may feature one or more injection molds 20 having multiple mold cavities 26 wherein the gate regions 42 are opened/closed substantially simultaneously. Alternately, the present disclosure may also feature one or more injection molds 20 defining multiple mold cavities 26 wherein the gate regions 42 of the injection molds 20 and the nozzle assemblies 10 may be moved independently with respect to each other such that the opening/closing of a specific mold cavity 26 may be controlled independently of the other mold cavities 26.
Control systems using hydraulic fluid, pressurized air and electric motors in combination with numerous switches and a controller may be used to control both the positioning of the platens and the application and removal of clamp-up force for opening and closing the mold. A locking device may also engage the tie bars of the machine. According to one embodiment, positioning of the platens includes opening and closing the mold halves 22, 24 along split line A as well as positioning of the cavity plate 24 (and gate 42) in relation to the nozzle tip 12 and valve stem 14 such that the valve stem 14 engages the gate 42 and seals the mold cavity space 26.
The mold halves 22, 24 may be closed later in the injection cycle to compress the plastic material in the mold cavity space 26 after a predetermined amount of material has been injected. The gate 42 may be closed by moving the cavity plate 24 so that the gate 42 engages the valve stem 14.
While the present disclosure has been described wherein the injection mold 20 moves relative to the nozzle assembly 10, this is not a limitation of the present disclosure and the nozzle assembly 10 may be moved relative to the injection mold 20 provided the valve gating portion 93 (e.g., valve stem 14) remains substantially stationary with respect to the nozzle assembly 10. Additionally, while the present disclosure has been described wherein valve gating portion 93 includes a valve stem 14, this is not a limitation of the present disclosure.
Referring to
The nozzle tip 91 may be removably secured to the nozzle body 12 in any manner known to those skilled in the art such as, but not limited to, a threaded connection or the like. Alternatively, the nozzle tip 91 may be an integral or unitary element with the nozzle body 12. For example, the nozzle tip 91 may be manufactured from a single piece of material or may be permanently joined to the nozzle body 12 (for example by welding or the like).
The nozzle tip 91 may comprise a valve gating portion 93 and a tip passageway 94. The tip passageway 94 is fluidly coupled to the melt channel 16. The valve gating portion 93 may be sized and shaped to seal against at least a portion of the gate 42 when the nozzle assembly 10 and/or injection mold 20 are moved towards each other as described above and shown in
As mentioned above, the present disclosure is not intended to be limited to a system or method which must satisfy one or more of any stated or implied object or feature of the invention and should not be limited to the preferred, exemplary, or primary embodiment(s) described herein. The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as is suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the claims when interpreted in accordance with breadth to which they are fairly, legally and equitably entitled.
