WO2021051190A1

WO2021051190A1 - Injection molding apparatus with adjustable valve pin

Info

Publication number: WO2021051190A1
Application number: PCT/CA2020/051238
Authority: WO
Inventors: Appu Jacob VARGHESE MANNOOR; Denis Babin
Original assignee: Mold-Masters (2007) Limited
Priority date: 2019-09-17
Filing date: 2020-09-15
Publication date: 2021-03-25

Abstract

An injection molding apparatus includes a mold assembly including a mold plate, a manifold, an actuator mounted on and upstream of the manifold, at least one nozzle coupled to and downstream of the manifold, and a valve pin having an upstream end coupled to the actuator and a downstream end opposite the upstream end distal from the actuator and received in the nozzle. The actuator includes a piston and an adjustment mechanism for adjusting an axial distance between the piston and the downstream end of the valve pin. The adjustment mechanism includes a valve pin holder coupling the valve pin to the piston. The valve pin holder is received in the piston and both having a shared axis of rotation and configured to prevent the valve pin holder from rotating about the shared axis.

Description

INJECTION MOLDING APPARATUS WITH ADJUSTABLE VALVE PIN

Inventors: Appu Jacob Varghese Mannoor, and Denis Babin

FIELD

[0001] The invention relates generally to an injection molding apparatus and, in particular, to an injection molding apparatus having an actuator with an adjustable valve pin.

BACKGROUND

[0002] Injection molding heats a material (e.g., plastic) into a melt, injects the melt into a cavity of a mold, and, after the melt cools and forms a solid article in the mold, ejects the article from the cavity. Melt flows into the cavity via a gate. In valve-gated injection molding, a pin regulates the flow of melt into a cavity by obstructing the melt flowing into the gate. An ability to adjust the fixed maximum distance the pin can extend into the gate is desirable.

BRIEF SUMMARY

[0003] In an illustrated embodiment, an injection molding apparatus is provided. The injection molding apparatus comprises: a mold assembly including a mold plate, a manifold, an actuator mounted on and upstream of the manifold, at least one nozzle coupled to and downstream of the manifold, and a valve pin having an upstream end coupled to the actuator and a downstream end opposite the upstream end distal from the actuator and received in the nozzle, the actuator for reciprocating the valve pin between an open position allowing a melt to pass through the nozzle and a closed position preventing the melt from passing through the nozzle, the actuator including a piston and an adjustment mechanism for adjusting an axial distance between the piston and the downstream end of the valve pin, the adjustment mechanism including a valve pin holder coupling the valve pin to the piston, the valve pin holder received in the piston, the valve pin holder and the piston having a shared axis of rotation and both configured to prevent the valve pin holder from rotating about the shared axis. [0004] The piston can include a radially extending member and an axially extending member central to the radially extending member, the axially extending member defining a bore to receive the valve pin holder.

[0005] The adjustment mechanism can include a sleeve received in the bore, the sleeve defining a channel. The channel can include an upstream end and a downstream end opposite of the upstream end of the channel. The sleeve can include an internally threaded portion at the downstream end of the channel. The valve pin holder can include an upstream end and a downstream end opposite of the upstream end of the valve pin holder. The valve pin holder can include an externally threaded portion at the upstream end of the valve pin holder. The externally threaded portion of the valve pin holder can in part be received in and mated with the internally threaded portion of the sleeve.

[0006] The bore can include a shoulder abutting the downstream end of the sleeve.

[0007] The adjustment mechanism can include an externally threaded member received in the bore upstream of and abutting the upstream end of the sleeve, the externally threaded member mated with an internally threaded portion of the bore.

[0008] The adjustment mechanism can include a set screw received in and mated with another internally threaded portion upstream of the internally threaded portion at the downstream end of the channel.

[0009] The valve pin holder can include a slot and the valve pin can include a head received in the slot.

[0010] The slot can include a flat portion matching another flat portion of the valve pin head to prevent the valve pin from rotating about the shared axis.

[0011] The actuator can include a housing having a slot and the actuator can include a key received in the slot, the key having a flat portion matching another flat portion of the axially extending member to prevent the axially extending member from rotating about the shared axis.

BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 is a schematic view of an injection molding apparatus, according to an embodiment of the present application;

[0013] FIG. 2 is a schematic view of a mold assembly of FIG. 1, according to an embodiment of the present application;

[0014] FIG. 3 is a sectioned view of a portion of the mold assembly of FIG. 2, according to an embodiment of the present application;

[0015] FIG. 4 is a perspective view of an actuator of FIG. 2;

[0016] FIG. 5 is a top view of the actuator of FIG. 4;

[0017] FIG. 6 is a sectioned view of the actuator of FIG. 5 taken along the line A- A;

[0018] FIG. 7 is a sectioned view of the actuator of FIG. 2;

[0019] FIG. 8 is a sectioned view of the actuator of FIG. 7 taken along the line B-B; and

[0020] FIG. 9 is a sectioned view of the actuator of FIG. 7 taken along the line C-C. DETAILED DESCRIPTION

[0021] Specific embodiments of the present application are now described with reference to the figures. The following detailed description is merely exemplary in nature and is not intended to limit the concepts and uses of the concepts. Furthermore, there is no intention to be restricted by any expressed or implied theory in the present disclosure. In the description, “downstream” is used with reference to the direction of the melt flow from an injector to a mold cavity, and also with reference to the order of components, or features thereof, through which the melt flows from the injector to the mold cavity, whereas “upstream” is used with reference to the opposite direction.

[0022] FIG. 1 is a schematic side view of an injection molding apparatus 10 comprising: an injection unit 15, a mold assembly 20, and a clamping unit 25. Referring to FIG. 2, mold assembly 20 includes a moving half 30 and a stationary half 35. Clamping unit 25 is configured to move moving half 30 towards stationary half 35 to close mold assembly 20 and away from stationary half 35 to open mold assembly 20. Moving half 30 includes a core plate 40 and a stripper plate 45. Stationary half 35 includes a cavity plate 50, a manifold plate 55 housing a manifold 60, and, depending on the application of injection molding apparatus 10, other plates 62. Mold assembly 20 is bounded by a clamp plate 72 on each end thereof (see FIG. 2). (Persons skilled in the art would appreciate that, depending on the application, some plates can be combined into one plate. For example, clamp plate 72 can be combined with core plate 40.)

[0023] Mold assembly 20 comprises a plurality of nozzles 68 (and will henceforth be referred to individually as nozzle 68 and collectively as nozzles 68). Manifold 60 is a melt delivery body, which, depending on the application of injection molding apparatus 10, can include a network of melt channels (not shown) for distributing melt from injection unit 15 to nozzles 68. Core plate 40 includes a plurality of cores 65. Cavity plate 50 includes a plurality of cavities 70 (and will henceforth be referred to individually as cavity 70 and collectively as cavities 70).

[0024] In operation, clamping unit 25 closes mold assembly 20 and clamps mold assembly 20 shut, in a closed position, to prevent mold assembly 20 from opening under the pressure of melt being injected, by injection unit 15, into cavities 70. With mold assembly 20 clamped in the closed position, melt is injected in to a space 75, shaped and dimensioned to create an article (not shown), between core 65 and corresponding cavity 70. When the article is ready to depart mold assembly 20, the article clings to core 65. To remove the article from core 65, mold assembly 20 opens allowing stripper plate 45 to move upstream to eject the article from core 65.

[0025] Mold assembly 20 comprises manifold 60 housed in manifold plate 55, a mold plate 100 upstream and in contact with manifold plate 55, and an actuator 64 mounted on and upstream of manifold 60. Mold plate 100 is actively cooled by cooling lines 101. In some embodiments, mold plate 100 is clamp plate 72. In some embodiments, mold assembly 20 comprises a plurality of actuators 64 (and will henceforth be referred to individually as actuator 64 and collectively as actuators 64). [0026] Referring to FIG. 3 showing a sectioned view of a portion of injection molding apparatus 10 according to an embodiment of the present application. Actuator 64 includes a housing 80 and a piston 85 housed in housing 80. Actuator 64 is for reciprocating a valve pin 95 between an open position allowing a melt (not shown) to pass through nozzle 68 and a closed position preventing the melt from passing through nozzle 68. Nozzle 68 is coupled to and downstream of manifold 60.

[0027] FIG. 4 and FIG. 5 are a top perspective view and top view, respectively, of actuator 64 according to an embodiment of the present application. FIG. 6 is a sectioned view of actuator 64 along line A-A of FIG. 5 according to an embodiment of the present application. Actuator 64 includes an adjustment mechanism 120. Piston 85 includes a radially extending member 125 and an axially extending member 130 central to the radially extending member 125. Axially extending member 130 defines a bore 135 having a step 140. Bore 135 has an upstream end 145 and a downstream end 150 opposite upstream end 145. Valve pin 95 has an upstream end 155 coupled to actuator 64 and a downstream end 160 opposite upstream end 155 distal from actuator 64 and received in nozzle 68 (see FIG. 3). Adjustment mechanism 120 is for adjusting an axial distance D between downstream end 160 of valve pin 95 and piston 85. Adjustment mechanism 120 includes a valve pin holder 165 coupling valve pin 95 to piston 85. Valve pin holder 165 has an upstream end 170 and a downstream end 175 opposite upstream end 170. Valve pin holder 165 is received in piston 85. Both valve pin holder 165 and piston 85 have a shared axis of rotation axis X (see FIG. 3). Both valve pin holder 165 and piston 85 are configured to prevent valve pin holder 165 from rotating about axis X. Valve pin holder 165 includes a flat portion 180 at downstream end 175 matching a flat portion 185 of bore 135 at downstream end 150 to prevent valve pin holder 165 from rotating about axis X when valve pin holder 165 is received in bore 135 (see FIG. 8).

[0028] Adjustment mechanism 120 includes a sleeve 190 received in bore 135 upstream of valve pin holder 165. Sleeve 190 has an upstream end 195 and a downstream end 200 opposite upstream end 195. Sleeve 190 defines a channel 205. Channel 205 includes an internally threaded portion 210 at downstream end 200. Valve pin holder 165 includes an externally threaded portion 215 at upstream end 170. Externally threaded portion 215 is, at least in part, received in and mated with internally threaded portion 210 of sleeve 190.

[0029] Adjustment mechanism 120 includes an externally threaded member 220 received in bore 135 upstream of and abutting upstream end 195 of sleeve 190. Bore 135 includes an internally threaded portion 225 at upstream end 145. Externally threaded member 220 is, at least in part, mated with internally threaded portion 225. Channel 205 includes an internally threaded portion 230 upstream of internally threaded portion 210. Adjustment mechanism 120 includes a set screw 235 received in and mated with internally threaded portion 230 abutting upstream end 170 of valve pin holder 165.

[0030] Referring to FIG. 8, valve pin 95 includes a valve pin head 240 received in a slot 245 of valve pin holder 165. Slot 245 includes a flat portion 250 matching a flat portion 255 of valve pin head 240 to prevent valve pin 95 from rotating about axis X.

[0031] Referring to FIG. 9, actuator housing 80 includes a slot 260. Actuator 64 includes a key 265 received in slot 260. Key 265 includes a flat portion 270 matching a flat portion 275 of axially extending member 130 to prevent axially extending member 130 from rotating about axis X. Key 265 is secured in slot 260 by screws 290.

[0032] Valve pin 95, piston 85, sleeve 190, and externally threaded member 220 all have a shared axis of rotation axis X. Externally threaded member defines a bore 280 with a hexagonal cross-section. Channel 205 includes a portion 285 with a hexagonal cross-section at upstream end 195.

[0033] Adjusting distance D can be effected by loosening externally threaded member 220 from bore 135, loosening set screw 235 from channel 205, rotating sleeve 190 with a hex tool inserted into portion 285, tightening set screw 235 against valve pin holder 165, and tightening externally threaded member 220 to urge sleeve 190 against shoulder 140.

[0034] Valve pin 95 can be replaced without removing actuator 64, and depending on the application, without draining hydraulic fluid (not shown). Valve pin 95 can be replaced by removing externally threaded member 220, removing adjustment mechanism 120 by threading a screw into channel 205 and pulling adjustment mechanism 120 out along with valve pin 95. Valve pin 95 can be slid out of valve pin holder 165 via slot 245. A new valve pin 95 can be placed in valve pin holder 165 and the process reversed to secure the new valve pin 95 to actuator 64. This way, valve pin 95 can be changed out without having to open actuator 64, remove the plates of the mold assembly 20, or drain any fluid.

[0035] Valve pin 95 can be left in place and actuator 64 can be removed. Valve pin 95 can be left in place while actuator assemblies are swapped out by removing externally threaded member 220, removing the sleeve 190 by rotating it to loosen from internally threaded portion 210 of sleeve 190. Actuator 64 can now be removed with valve pin 95 left in place along with valve pin holder 165.

[0036] While various embodiments according to the present application have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons of ordinary relevant skills in the relevant art that various changes in form and detail can be made therein without departing from the scope of the invention. Thus, the breadth and scope of the present invention should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the appended claims and their equivalents.

Claims

CLAIMS What is claimed is:

1. An injection molding apparatus comprising: a mold assembly including a mold plate, a manifold, an actuator mounted on and upstream of the manifold, at least one nozzle coupled to and downstream of the manifold, and a valve pin having an upstream end coupled to the actuator and a downstream end opposite the upstream end distal from the actuator and received in the nozzle, the actuator for reciprocating the valve pin between an open position allowing a melt to pass through the nozzle and a closed position preventing the melt from passing through the nozzle, the actuator including a piston and an adjustment mechanism for adjusting an axial distance between the piston and the downstream end of the valve pin, the adjustment mechanism including a valve pin holder coupling the valve pin to the piston, the valve pin holder received in the piston, the valve pin holder and the piston having a shared axis of rotation and both configured to prevent the valve pin holder from rotating about the shared axis.

2. The injection molding apparatus of claim 1, wherein the piston includes a radially extending member and an axially extending member central to the radially extending member, the axially extending member defining a bore to receive the valve pin holder.

3. The injection molding apparatus of claim 2, wherein the adjustment mechanism includes a sleeve received in the bore, the sleeve defining a channel, the channel including an upstream end and a downstream end opposite of the upstream end of the channel, the sleeve including an internally threaded portion at the downstream end of the channel, the valve pin holder including an upstream end and a downstream end opposite of the upstream end of the valve pin holder, the valve pin holder including externally threaded portion at the upstream end of the valve pin holder, the externally threaded portion of the valve pin holder in part received in and mated with the internally threaded portion of the sleeve.

4. The injection molding apparatus of claim 3, wherein the bore includes a shoulder abutting the downstream end of the sleeve.

5. The injection molding apparatus of claim 4, wherein the adjustment mechanism includes an externally threaded member received in the bore upstream of and abutting the upstream end of the sleeve, the externally threaded member mated with an internally threaded portion of the bore.

6. The injection molding apparatus of claim 5, wherein the adjustment mechanism includes a set screw received in and mated with another internally threaded portion upstream of the internally threaded portion at the downstream end of the channel.

7. The injection molding apparatus of claim 6, wherein the valve pin holder includes a slot and the valve pin includes a head received in the slot.

8. The injection molding apparatus of claim 7, wherein the slot includes a flat portion matching another flat portion of the valve pin head to prevent the valve pin from rotating about the shared axis.

9. The injection molding apparatus of claim 6, wherein the actuator includes a housing having a slot and the actuator includes a key received in the slot, the key having a flat portion matching another flat portion of the axially extending member to prevent the axially extending member from rotating about the shared axis.