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Title:
INJECTION MOLDING FLOW CONTROL APPARATUS AND METHOD
Document Type and Number:
WIPO Patent Application WO/2013/177526
Kind Code:
A1
Abstract:
Apparatus for routing gas entrapped within a hydraulic drive fluid comprising an actuator cylinder having a bore that has an inner surface and a piston received within the bore of the cylinder for reciprocal upstream-downstream movement of the piston within the bore of the cylinder, the piston comprising a body sealed against the inner surface of the cylinder, a bleed bore formed within the body of the piston, the bleed bore having an upstream port and a downstream port, the upstream and downstream ports enabling hydraulic fluid and the entrapped gas to flow through the bleed bore in the piston.

Inventors:
GALATI VITO (US)
LEE CHRISTOPHER W (US)
Application Number:
US2013/042674
Publication Date:
November 28, 2013
Filing Date:
May 24, 2013
Export Citation:
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Assignee:
SYNVENTIVE MOLDING SOLUTIONS (US)
GALATI VITO (US)
LEE CHRISTOPHER W (US)
International Classes:
F15B15/14; B29C45/28; F15B21/04
Foreign References:
FR1211772A1960-03-18
JPH08312609A1996-11-26
US4389002A1983-06-21
Attorney, Agent or Firm:
OLIVERIO, M., Lawrence (100 Cambridge Street Suite 210, Boston MA, US)
Download PDF:
Claims:
What is claimed is:

1 Apparatus for routing gas entrapped within a hydraulic drive fluid used in driving a valve pin, the apparatus comprising an actuator comprised of a cylinder having a bore that has an inner surface and a piston received within the bore of the cylinder for reciprocal upstream-downstream movement of the piston within the bore of the cylinder,

the drive fluid being input and output under pressure to and from a fluid sealed chamber formed between the piston and the cylinder to cause the piston to move upstream and downstream,

the piston comprising a body having an outer surface sealed against the inner surface of the cylinder to form the fluid sealed chamber,

the body of the piston being drivable to travel between upstream and downstream positions and maintaining a seal against leakage of fluid within the fluid sealed chamber during the course of travel;

wherein a bleed bore is formed within the body of the piston, the bleed bore having an upstream port formed in an upstream surface of the body of the piston against which fluid in the sealed chamber engages under pressure to drive the piston downstream,

the bleed bore having a downstream port formed in a downstream surface of the body of the piston against which fluid engages under pressure to drive the piston upstream, the upstream and downstream ports communicating with the fluid sealed chamber to enable hydraulic fluid and the entrapped gas to flow through the bleed bore in the piston between the upstream surface and the downstream surfaces of the piston.

2. The apparatus of claim 1 wherein the body of the piston comprises a first portion and a flange portion disposed between upstream and downstream ends of the first portion, the flange portion having an outer surface sealed against the inner surface of the cylinder, bleed bore being formed within the flange.

3. The apparatus of claim 1 including a valve mechanism disposed within the bleed bore.

4. The apparatus of claim 3 wherein the valve mechanism comprises an insert fixedly mounted within the bleed bore and a flow restriction member disposed within the bleed bore, the insert having a bore enabling flow of drive fluid between the upstream and downstream ports of the bleed bore, the flow restriction member being adapted to travel within the bleed bore under force of flow of the drive fluid between a position of

engagement with an internally disposed end surface of the insert and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore.

5. The apparatus of claim 4 wherein the internally disposed end surface of the insert and the flow restriction member are adapted to allow flow of drive fluid through the bore of the insert at a restricted rate of flow on engagement of the flow restriction member with the internally disposed end surface of the insert.

6. The apparatus of claim 4 wherein the flow restriction member is adapted to close off flow through the one or the other of the upstream and downstream ports of the bleed bore on engagement of the flow restriction member with the surface leading to the one or the other of the upstream and downstream ports under force of flow of the drive fluid.

7. The apparatus of claim 4 wherein one of the flow restriction member and the internally disposed end surface of the insert has a groove that enables the drive fluid to flow through the bore of the insert on engagement of the flow restriction member with the internally disposed end surface of the insert.

8. The apparatus of claim 4 wherein the flow restriction member comprises a pin, the groove being formed in a surface on the pin that engages the internally disposed end surface of the insert.

9. The apparatus of claim 4 wherein the flow restriction member comprises a ball, the groove being formed in the internally disposed end surface of the insert.

10. The apparatus of claim 3 wherein the valve mechanism comprises a flow restriction member disposed within the bleed bore, the flow restriction member being adapted to travel within the bleed bore under force of flow of the drive fluid between a travel stopped position within the bleed bore where flow of the drive fluid is enabled at a restricted rate of flow and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore where flow of the drive fluid is closed off or stopped.

1 1. The apparatus of claim 1 wherein the bleed bore includes an internally disposed surface against which a flow restriction member is engageable to enable flow of the drive fluid through the feed bore at a restricted rate of flow.

12. The apparatus of claim 2 wherein the first portion of the piston has an outer surface upstream and downstream of the flange that are sealed against the inner surface of the cylinder bore, the sealed chamber comprising an upstream sealed chamber and a downstream sealed chamber formed into the inner surface of the cylinder, the upstream and downstream chambers being in fluid communication via the bleed bore disposed through the flange portion of the piston.

13. An apparatus for routing gas entrapped within a hydraulic drive fluid used in driving a valve pin, the apparatus comprising a cylinder having a bore that has an inner surface and a piston received within the bore of the cylinder for reciprocal upstream-downstream movement of the piston within the bore of the cylinder,

the drive fluid being input and output under pressure to and from a fluid sealed chamber formed between the piston and the cylinder to cause the piston to move upstream and downstream,

the piston comprising a body having an outer surface sealed against the inner surface of the cylinder to form the fluid sealed chamber,

the body of the piston being drivable to travel between upstream and downstream positions and maintaining a seal against leakage of fluid within the fluid sealed chamber during the course of travel;

wherein a bleed bore is formed within the body of the piston, the bleed bore having an upstream port formed in an upstream surface of the body the piston against which fluid in the sealed chamber engages under pressure to drive the piston downstream, the bleed bore having a downstream port formed in a downstream surface of the body of the piston against which fluid engages under pressure to drive the piston upstream;

the upstream and downstream ports communicating with the fluid sealed chamber to enable hydraulic fluid and the entrapped gas to flow through the bleed bore in the piston between the upstream surface and the downstream surfaces of the piston;

the body of the piston comprising a first portion and a flange portion disposed between upstream and downstream ends of the first portion, the flange portion having an outer surface sealed against the inner surface of the cylinder, bleed bore being formed within the flange; the apparatus including a flow restriction member disposed within the bleed bore, the flow restriction member being adapted to travel within the bleed bore under force of flow of the drive fluid between a travel stopped position within the bleed bore where flow of the drive fluid is enable at a restricted rate of flow and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore where flow of the drive fluid is closed off or stopped;

the bleed bore including an internally disposed surface against which the flow restriction member is engageable to enable flow of the drive fluid through the feed bore at a restricted rate of flow,

14. A method of bleeding gas entrapped within the flow of a drive fluid used in driving a valve pin in an apparatus comprised of an actuator that is comprised of a cylinder having a bore that has an inner surface and a piston received within the bore of the cylinder for reciprocal upstream-downstream movement of the piston within the bore of the cylinder, the drive fluid being input and output under pressure to and from a fluid sealed chamber formed between the piston and the cylinder to cause the piston to move upstream and downstream,

the piston comprising a body having an outer surface sealed against the inner surface of the cylinder to form the fluid sealed chamber,

the body of the piston being drivable to travel between upstream and downstream positions and maintaining a seal against leakage of fluid within the fluid sealed chamber during the course of travel;

the method comprising:

forming a bleed bore within the body of the piston, the bleed bore having an upstream port formed in an upstream surface of the body of the piston against which fluid in the sealed chamber engages under pressure to drive the piston downstream, the bleed bore having a downstream port formed in a downstream surface of the body of the piston against which fluid engages under pressure to drive the piston upstream;

forming the upstream and downstream ports to communicate with the fluid sealed chamber to enable hydraulic fluid and the entrapped gas to flow through the bleed bore in the piston between the upstream surface and the downstream surfaces of the piston. Such a method typically further comprises disposing a valve mechanism within the bleed bore to restrict the flow of drive fluid through the bleed bore.

15. The method of claim 14 further comprising;

forming the piston into a first portion and a flange portion disposed between upstream and downstream ends of the first portion,

forming the flange portion with an outer surface adapted to seal against the inner surface of the cylinder, and,

forming the bleed bore within the flange.

16. The method of claim 14 further comprising:

disposing a flow restriction member within the bleed bore, and,

adapting the flow restriction member to travel within the bleed bore under force of flow of the drive fluid between a travel stopped position within the bleed bore where flow of the drive fluid is enabled at a restricted rate of flow and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore where flow of the drive fluid is closed off or stopped.

17. The method of claim 14 further comprising forming the bleed bore to include an internally disposed surface against which the flow restriction member is engageable to enable flow of the drive fluid through the feed bore at a restricted rate of flow.

18. The method of claim 14 further comprising:

fixedly mounting an insert within the bleed bore, the insert having a bore enabling flow of drive fluid between the upstream and downstream ports of the bleed bore,

disposing a flow restriction member within the bleed bore between the insert and one or the other of the upstream and downstream ports of the bleed bore, and,

adapting the flow restriction member to be engageable with an internally disposed end surface of the insert and a surface leading to the one or the other of the upstream and downstream ports of the bleed bore.

Description:
INJECTION MOLDING FLOW CONTROL APPARATUS AND METHOD

PRIORITY APPLICATION

[01] This application claims priority to U.S. Serial No. 61/651 ,861 filed 25 May 2012.

RELATED APPLICATIONS

[02] The disclosures of all of the following are incorporated by reference in their entirety as if fully set forth herein: U.S. Patent No. 5,894,025, U.S. Patent No. 6,062,840, U.S.

Patent No. 6,294,122, U.S. Patent No. 6,309,208, U.S. Patent No. 6,287,107, U.S. Patent No. 6,343,921 , U.S. Patent No. 6,343,922, U.S. Patent No. 6,254,377, U.S. Patent No. 6,261 ,075, U.S. Patent No. 6,361 ,300 (7006), U.S. Patent No. 6,419,870, U.S. Patent No. 6,464,909 (7031 ), U.S. Patent No. 6,599,116, U.S. Patent No. 6,824,379, U.S. Patent No. 7,234,929 (7075US1 ), U.S. Patent No. 7,419,625 (7075US2), U.S. Patent No. 7,569,169 (7075US3), U.S. Patent Application Serial No. 10/214,118, filed August 8, 2002 (7006), U.S. Patent No. 7,029,268 (7077US1 ), U.S. Patent No. 7,270,537 (7077US2), U.S. Patent No. 7,597,828 (7077US3), U.S. Patent Application Serial No. 09/699,856 filed October 30, 2000 (7056), U.S. Patent Application Serial No. 10/269,927 filed October 11 , 2002 (7031 ), U.S. Application Serial No. 09/503,832 filed February, 15, 2000 (7053), U.S. Application Serial No. 09/656,846 filed September 7, 2000 (7060), U.S. Application Serial No.

10/006,504 filed December 3, 2001 , (7068) and U.S. Application Serial No. 10/101 ,278 filed March, 19, 2002 (7070).

BACKGROUND OF THE INVENTION

[03] Injection molding systems have been developed having bleed valves that allow air or gas that is embedded in the liquid hydraulic fluid used in the hydraulic drive system to be purged from the piping, tubing, fluid chambers and hydraulic fluid lines leading to and from the cylinder of the actuator.

SUMMARY OF THE INVENTION

[04] In accordance with the invention there is provided an apparatus for routing gas entrapped within a hydraulic drive fluid used in driving a valve pin, the apparatus being comprised of a cylinder having a bore that has an inner surface and a piston received within the bore of the cylinder for reciprocal upstream-downstream movement of the piston within the bore of the cylinder, the drive fluid being input and output under pressure to and from a fluid sealed chamber formed between the piston and the cylinder to cause the piston to move upstream and downstream,

the piston comprising a body having an outer surface sealed against the inner surface of the cylinder to form the fluid sealed chamber,

the body of the piston being drivable to travel between upstream and downstream positions and maintaining a seal against leakage of fluid within the fluid sealed chamber during the course of travel;

wherein a bleed bore is formed within the body of the piston, the bleed bore having an upstream port formed in an upstream surface of the body of the piston against which fluid in the sealed chamber engages under pressure to drive the piston downstream, the bleed bore having a downstream port formed in a downstream surface of the body of the piston against which fluid engages under pressure to drive the piston upstream;

the upstream and downstream ports communicating with the fluid sealed chamber to enable hydraulic fluid and the entrapped gas to flow through the bleed bore in the piston between the upstream surface and the downstream surfaces of the piston.

[05] The body of the piston typically comprises a first portion and a flange portion disposed between upstream and downstream ends of the first portion, the flange portion having an outer surface sealed against the inner surface of the cylinder, bleed bore being formed within the flange.

[06] The apparatus preferably includes a valve mechanism disposed within the bleed bore.

[07] The valve mechanism can comprise an insert fixedly mounted within the bleed bore and a flow restriction member disposed within the bleed bore, the insert having a bore enabling flow of drive fluid between the upstream and downstream ports of the bleed bore, the flow restriction member being adapted to travel within the bleed bore under force of flow of the drive fluid between a position of engagement with an internally disposed end surface of the insert and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore. [08] The internally disposed end surface of the insert and the flow restriction member are preferably adapted to allow flow of drive fluid through the bore of the insert at a restricted rate of flow on engagement of the flow restriction member with the internally disposed end surface of the insert.

[09] The flow restriction member is preferably adapted to close off flow through the one or the other of the upstream and downstream ports of the bleed bore on engagement of the flow restriction member with the surface leading to the one or the other of the upstream and downstream ports under force of flow of the drive fluid.

[10] Typically, one of the flow restriction member and the internally disposed end surface of the insert has a groove that enables the drive fluid to flow through the bore of the insert on engagement of the flow restriction member with the internally disposed end surface of the insert.

[11] The flow restriction member can comprise a pin, the groove being formed in a surface on the pin that engages the internally disposed end surface of the insert.

[12] The flow restriction member can comprise a ball, the groove being formed in the internally disposed end surface of the insert.

[13] The valve mechanism preferably comprises a flow restriction member disposed within the bleed bore, the flow restriction member being adapted to travel within the bleed bore under force of flow of the drive fluid between a travel stopped position within the bleed bore where flow of the drive fluid is enabled at a restricted rate of flow and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore where flow of the drive fluid is closed off or stopped.

[14] The bleed bore preferably includes an internally disposed surface against which the flow restriction member is engageable to enable flow of the drive fluid through the feed bore at a restricted rate of flow.

[15] The first portion of the piston typically has an outer surface upstream and downstream of the flange that are sealed against the inner surface of the cylinder bore, the sealed chamber comprising an upstream sealed chamber and a downstream sealed chamber formed into the inner surface of the cylinder, the upstream and downstream chambers being in fluid communication via the bleed bore disposed through the flange portion of the piston. [16] In another aspect of the invention there is provided, an apparatus for routing gas entrapped within a hydraulic drive fluid used in driving a valve pin the apparatus being comprised of a cylinder having a bore that has an inner surface and a piston received within the bore of the cylinder for reciprocal upstream-downstream movement of the piston within the bore of the cylinder,

the drive fluid being input and output under pressure to and from a fluid sealed chamber formed between the piston and the cylinder to cause the piston to move upstream and downstream,

the piston comprising a body having an outer surface sealed against the inner surface of the cylinder to form the fluid sealed chamber,

the body of the piston being drivable to travel between upstream and downstream positions and maintaining a seal against leakage of fluid within the fluid sealed chamber during the course of travel;

wherein a bleed bore is formed within the body of the piston, the bleed bore having an upstream port formed in an upstream surface of the body the piston against which fluid in the sealed chamber engages under pressure to drive the piston downstream, the bleed bore having a downstream port formed in a downstream surface of the body of the piston against which fluid engages under pressure to drive the piston upstream;

the upstream and downstream ports communicating with the fluid sealed chamber to enable hydraulic fluid and the entrapped gas to flow through the bleed bore in the piston between the upstream surface and the downstream surfaces of the piston;

the body of the piston comprising a first portion and a flange portion disposed between upstream and downstream ends of the first portion, the flange portion having an outer surface sealed against the inner surface of the cylinder, bleed bore being formed within the flange;

the apparatus including a flow restriction member disposed within the bleed bore, the flow restriction member being adapted to travel within the bleed bore under force of flow of the drive fluid between a travel stopped position within the bleed bore where flow of the drive fluid is enable at a restricted rate of flow and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore where flow of the drive fluid is closed off or stopped; the bleed bore including an internally disposed surface against which the flow restriction member is engageable to enable flow of the drive fluid through the feed bore at a restricted rate of flow.

[17] In another aspect of the invention there is provided, a method of bleeding gas entrapped within the flow of a drive fluid used in driving a valve pin in an apparatus comprising an actuator comprised of a cylinder having a bore that has an inner surface and a piston received within the bore of the cylinder for reciprocal upstream-downstream movement of the piston within the bore of the cylinder, the drive fluid being input and output under pressure to and from a fluid sealed chamber formed between the piston and the cylinder to cause the piston to move upstream and downstream,

the piston comprising a body having an outer surface sealed against the inner surface of the cylinder to form the fluid sealed chamber,

the body of the piston being drivable to travel between upstream and downstream positions and maintaining a seal against leakage of fluid within the fluid sealed chamber during the course of travel;

the method comprising:

forming a bleed bore within the body of the piston, the bleed bore having an upstream port formed in an upstream surface of the body of the piston against which fluid in the sealed chamber engages under pressure to drive the piston downstream, the bleed bore having a downstream port formed in a downstream surface of the body of the piston against which fluid engages under pressure to drive the piston upstream;

forming the upstream and downstream ports to communicate with the fluid sealed chamber to enable hydraulic fluid and the entrapped gas to flow through the bleed bore in the piston between the upstream surface and the downstream surfaces of the piston.

[18] Such a method typically further comprises disposing a valve mechanism within the bleed bore to restrict the flow of drive fluid through the bleed bore.

[19] Such a method can further comprise:

forming the piston into a first portion and a flange portion disposed between upstream and downstream ends of the first portion,

forming the flange portion with an outer surface adapted to seal against the inner surface of the cylinder, and, forming the bleed bore within the flange.

[20] Such a method typically further comprises:

disposing a flow restriction member within the bleed bore, and,

adapting the flow restriction member to travel within the bleed bore under force of flow of the drive fluid between a travel stopped position within the bleed bore where flow of the drive fluid is enabled at a restricted rate of flow and a position of engagement with a surface leading to one or the other of the upstream and downstream ports of the bleed bore where flow of the drive fluid is closed off or stopped.

[21] Such a method can further comprise forming the bleed bore to include an internally disposed surface against which the flow restriction member is engageable to enable flow of the drive fluid through the feed bore at a restricted rate of flow.

[22] Such a method can further comprise:

fixedly mounting an insert within the bleed bore, the insert having a bore enabling flow of drive fluid between the upstream and downstream ports of the bleed bore, and, disposing a flow restriction member within the bleed bore between the insert and one or the other of the upstream and downstream ports of the bleed bore, and,

adapting the flow restriction member to be engageable with an internally disposed end surface of the insert and a surface leading to the one or the other of the upstream and downstream ports of the bleed bore.

Brief Description of the Drawings

[23] The above and further advantages of the invention may be better understood by referring to the following description in conjunction with the accompanying drawings in which:

[24] Fig. 1 is a cross-sectional side view of a prior art actuator system incorporating a bleed valve one within the cylinder housing of the actuator;

[25] Fig. 2 is an enlarged fragmentary cross-sectional side view of the actuator assembly 52 of FIG. 1 ;

[26] Fig. 3A is a top sectional perspective view of one embodiment of a bleed valve mounted within a flange of an actuator piston according to the invention; [27] Fig. 3B is a top perspective exploded view of the bleed valve embodiment of Fig. 3A;

[28] Fig. 3C is a side cross-sectional view of the bleed valve of Fig. 3A showing the pin of the valve in a downstream flow closed position;

[29] Fig. 3D is a side cross-sectional view of the bleed valve of Fig. 3A showing the pin of the valve in an upstream flow open position;

[30] Fig. 4 is a side cross-sectional view of an actuator having a floating pin bleed valve embedded within the body of the flange of a hydraulic actuator's piston, the piston shown in the downstream -most driven position within the actuator cylinder, the floating bleed valve pin being in a flow closed position under force of the downstream flow of the liquid hydraulic drive fluid;

[31] Fig. 5 is a side cross-sectional view of the Fig. 4 actuator showing the piston shown in the upstream-most driven position within the actuator cylinder, the floating bleed valve pin being in a flow open position under force of the upstream flow of the liquid hydraulic drive fluid;

[32] Fig. 6 is an enlarged view of the sealed liquid fluid chamber that is formed between the piston and the cylinder and sealed by O-rings of the Figs. 4, 5 actuator, showing the bleed valve pin in an upstream open position and showing a pocket of air disposed immediately below the inlet orifice of the valve readied for escape through the orifice under the force of upstream pressure from the hydraulic liquid being driven by the pump in the upstream piston-up position;

[33] Fig. 7 is enlarged detail view of the area encircled by arrows 7-7 in Fig. 4, showing a later in time relative to the view of Fig. 6 showing the pin still in the upstream position with the pocket of air reduced in size due to a portion of the original pocket of air having escaped upstream through the valve and showing some of the liquid hydraulic fluid flowing upstream through the valve passage way travelling toward eventual emptying into the reservoir tank 500;

[34] Fig. 8 is an enlarged detail view of the area encircled by arrows 8-8 in Fig. 5 at a point in time in an injection cycle where the directional valve 600 has been switched to the downstream drive position 604 seen in Fig, 10B showing the liquid hydraulic fluid being driven in the downstream, direction thus causing the bleed valve pin to be driven to the flow closed position and causing the piston to be driven to the fully downstream position and showing an air bubble or pocket having been driven partially downstream within the flow of the liquid hydraulic fluid to a position within the fluid sealed chamber formed between the piston and the cylinder;

[35] Fig. 9 is an enlarged view similar to the Fig. 8 view, later in time in an injection cycle when the directional valve 600 has been switched to the upstream drive position 602 seen in Fig. 10A showing the liquid hydraulic fluid being driven in the upstream direction thus causing the piston to be driven to the fully upstream position and thus causing the bleed valve pin to be driven to the flow open position and showing an air bubble or pocket having been driven further upstream on the upstream drive cycle within the liquid drive fluid toward the fluid reservoir tank 500;

[36] Fig. 10A is a cross-sectional view of a liquid hydraulic system showing a liquid reservoir tank 500 containing the liquid hydraulic fluid and a pump interconnected between the fluid reservoir and the inlet lines or flow channels or tubes leading into and out of the sealed fluid drive chamber formed between the actuator piston and the actuator cylinder, a controllable directional valve being disposed between the pump and the sealed fluid chamber, the actuator being in the up position shown in Fig. 7 and an air bubble A has just passed through the bleed valve 700;

[37] Fig. 10 B is a cross-sectional view similar to Fig. 10A but showing the actuator in the down position shown in Fig. 8 in which there is no flow of fluid through the bleed valve 700;

[38] Fig. 11 is an enlarged sectional view similar to the Figs. 6-9 views showing another embodiment of a bleed valve having a floating ball, the valve shown at a position in time during an injection cycle where the ball is driven to an upstream flow open position with a pocket of air shown at the entrance to the exhaust orifice of the bleed valve under the force of hydraulic fluid being driven in the upstream, piston-up direction such that the air bubble or pocket can bleed out or escape toward the tank 500;

[39] Fig. 12 is a further enlarged sectional view of the ball and screw-plug

components of the bleed valve embodiment of Fig. 11 showing the ball seated in its upstream-most position at the downstream orifice of the screw-plug component, the downstream orifice end of the screw plug having a transverse groove that enables fluid and air to bleed around the surface of the ball and through the transverse groove and eventually upstream through the axial orifice of the screw-plug while the ball is seated within the orifice at the downstream end of the screw-plug;

[40] Fig. 13 is an enlarged sectional view similar to the Fig. 12 view showing the floating ball positioned at a later point in time in the injection cycle where the directional valve 600 has been reversed to the downstream drive position 602 and the liquid hydraulic drive fluid is being driven by the pump in a downstream direction thus driving the ball to the downstream fluid closed position;

[41] Fig. 14 is an enlarged perspective view similar to the Fig. 13 view showing more details of the relative contour and positioning of the groove and screw-plug components of the Figs. 1 1 , 12 bleed valve embodiment with the floating ball positioned at a point in time in the injection cycle where the directional valve 600 has been reversed to the downstream drive position 602 and the liquid hydraulic drive fluid is being driven by the pump in a downstream direction thus driving the ball to the downstream fluid closed position;

[42] Fig. 15 is an enlarged top perspective exploded view similar to the Fig. 14 view showing the screw-plug component exploded relative to the flange of the piston in which the screw-plug and floating ball are mounted;

[43] Fig. 16 is a top, front perspective view of another embodiment of a bleed valve mounted in a flange of an actuator piston according to the invention;

[44] Fig. 17 is an exploded view of the Fig. 16 apparatus;

[45] Fig. 18 is a side cross-sectional view of a floating ball bleed valve mounted in the flange of an actuator piston in an arrangement where the floating ball closes off bleed flow of liquid hydraulic drive fluid when the liquid hydraulic drive fluid is driven in the upstream direction, Fig. 18 showing the system at a point in time during the injection cycle where the hydraulic flow is downstream and the floating ball is in a position against the groove of the plug where flow of hydraulic fluid or entrapped gas or air is enabled to flow through the groove and the plug and thus bleed in the downstream direction of fluid flow;

[46] Fig. 19 is a view of the Fig. 18 apparatus at a point in time in the injection cycle where the hydraulic fluid is driven in the upstream direction thus driving the floating ball of the bleed valve into compressed engagement with the upstream orifice of the valve closing off flow of fluid and gas in the upstream direction of flow. DETAILED DESCRIPTION

[47] FIGS. 1 -2 illustrate an injection molding system 10 used to mold a plastic part. As illustrated, there is a mold part 12, typically called a core block, and a mold part 14, typically called a cavity block. Disposed over the upper mold part 14 is the hot runner manifold 16. As illustrated in, for example, FIGS. 1 and 2, the hot runner manifold 16 supports nozzles 18, which are threadably screwed therein. About each nozzle 18 there is provided a heater 20, for maintaining the melt material passing through the nozzle at its process temperature. Also, heat pipes may be employed in the nozzle 18, alone, or in conjunction with the band heaters 20, such as illustrated in U.S. Pat. No. 4,389,002.

[48] Fig. 2 illustrates a prior art embodiment of a bleed or check valve apparatus incorporated into an injection molding system, the check or bleed valve system comprising a floating pin 76 mounted within a check or bleed bore, a stop 104 for limiting travel of the floating pin 76 within the bleed bore and expansion plugs 108 for capping the ends of the bleed bore. In such a prior system the bleed bore of the check valve is formed within the body of the stationarily mounted actuator cylinder housing 54, the associated operable parts 76, 104 of the check or bleed valve being similarly mounted within the body of the cylinder housing 54.

[49] As illustrated between mold parts 12 and 14, there is a cavity 22 that determines the contour of the molded part being produced. Also, as noted in particular in FIG. 3, at the end of the nozzle 18, there is provided a nozzle tip 24, disposed about a nozzle insert 26.

[50] FIG. 2 illustrates the valve pin 28 in its closed position. The valve pin 28 extends through a central bore in the nozzle 18, and, in the embodiment illustrated, has a tapered end 30 that mates with a like tapered gate 32 in the mold. It should be noted that the invention is not limited to a particular type of nozzle arrangement, as different tip and insert configurations are possible. For example, the gate 32 could be formed in the nozzle, with the valve pin mating with the tapered surface of the tip. Furthermore, as shown in FIGS. 1 and 3, when gating directly onto an angled part surface, the valve pin can be contoured to match the part.

[51 ] FIG. 1 illustrates the machine nozzle 34 of the injection molding machine that feeds the molten plastic material through a porting arrangement that extends through the top clamping plate 36. This porting arrangement also feeds through a bore 38 in the hot runner manifold 16. The bore 38 feeds each of the nozzles 18.

[52] FIG. 1 also illustrates spacers 42 for properly positioning the clamping plate 36 relative to the mold part 14. The clamping plate 36 is cooled as illustrated by the water channels 44. To position the manifold 16 there is provided a locating pin 46 disposed between the manifold and the mold part. FIG. 1 also illustrates a series of support pads 48 for providing proper distancing and positioning between the mold part 14, the manifold 16, and the cooled clamping plate 36.

[53] As shown a hydraulic liquid fluid driven actuator 52 is connected to a well or source of liquid drive fluid 500, typically oil, that is pumped via a controllably operable pump, Fig. 10, in two directions, upstream and downstream via controlled adjustment of directional valve 600 having an upstream drive position 602 and a downstream drive position 604 where the hydraulic drive fluid 500 is driven so as drive the piston 56 and its interconnected valve pin 28 between upstream-most and downstream-most positions such as shown in Figs. 4/5 or 7/8 or 19/18.

[54] In a system according to the invention, a check or bleed valve 700 is formed within the body of the piston 56 of an actuator 52 as shown in Figs. 3A-19 such that the bleed or check valve 700 itself travels upstream U and downstream D together with the piston 56 during the course of an injection cycle. Preferably the bleed valve 700 is formed and mounted within the body of the flange 1 10 of the piston 56 with the exit 702 and entrance 704 ports of the bleed bore 706 of the valve 700 formed in the upstream 110a and downstream 1 10b surfaces of the flange 1 10 itself. The bleed valve or bore 700 could alternatively be formed within the first or main portion 57 of the piston 56 and otherwise function in the manner described herein where the bleed valve or bore 700 is disposed in the flange portion 1 10 of the piston 56.

[55] As shown in Figs. 3A-19, the check valve 700 can have a variety of

configurations. One embodiment, Figs. 3A-3D can employ an insert, plug or bushing 710, 710a, 710b fixedly mounted in the bleed bore 706 having an internally disposed surface 71 Ou and a pin 708 having an engagement surface 708u and a groove 708g for allowing fluid and air bubble A flow through the insert bore 710ib when the surfaces 708u and 71 Ou are engaged, Figs. 3A-3D. [56] Another embodiment, Figs. 1 1 -19, can comprise a ball 712 and an insert, plug or bushing 710 having a groove or port 71 Og for enabling fluid flow through the bore 710ib of the insert 710 when the ball 712 is engaged with the internally disposed surface 71 Ou of the insert 710.

[57] The bleed bore 706 of the apparatus preferably includes a surface 706ps leading to the port 704 that is complementary to the configuration of the end surface 708cs of the insert 708 or outer surface of the ball 712 such that the surfaces 706ps and 708cs are readily mated when engaged thus closing off flow of fluid 500 through port 704 as shown in Figs. 3C, 8, 13, 14, 16 for example.

[58] As shown in the Figs. 3A-3D examples, the insert 710 comprises two pieces 710a, 710b, an insert bore, 71 Oib formed in the center or axis of the assembly for allowing flow of fluid 500 therethrough. Similarly, in the Figs. 16, 17 embodiment, the insert 710 comprises two pieces, 710a, 710b. The two pieces 710a, 710b are fixedly mounted within the bleed bore 706 while the pin 710 or ball 712 is free floating within the bore 706 between the fixed pin 710 and the surface 706ps of the port 704.

[59] In the Figs. 3A-3D, 1 1 -17 embodiments, the valve 700 is arranged and adapted such that the pin 708 or ball 712 closes off flow through the port 704 as well as through the insert or valve bore 71 Oib when the drive fluid 500 is being pumped or driven in the downstream D direction. And, in such Figs. 3A-3D, 16-17 embodiments, a restricted rate of flow of fluid 500 is enabled and effected through bore 71 Oib in the upstream direction, when the pin surface 708u or ball 712 is engaged with the internally disposed surface 71 Ou of the insert 710 such restricted flow being enabled and effected by and through groove 708g, 71 Og.

[60] Conversely in the Figs. 18, 19 embodiment, the valve 700 is arranged and adapted to close off flow through the port 704 as well as through the insert or valve bore 71 Oib when the drive fluid 500 is being pumped or driven in the upstream U direction as shown in Fig. 19. And, in such Figs. 18, 19 embodiments, a restricted rate of flow of fluid 500 is enabled and effected in the downstream direction through bore 71 Oib as shown in Fig. 18, when the ball 712 (or pin surface 708u) is engaged with the internally disposed surface 71 Ou of the insert 710 such restricted flow being enabled and effected by and through groove 708g or 71 Og. Any of the pin 76, 708 or ball 712 and bleed bore 706 configurations as described herein can be employed in the alternative system of Figs. 18, 19 where the air bubble exhausts by travelling in from the upstream chamber 56u to the downstream chamber 56d in the downstream D direction.

[61] As shown by the series of Figures 4-1 OB, an air bubble A that may be entrapped within a fluid line 501 , 502 leading to or from the upstream sealed chamber 56u or downstream sealed chamber 56d of the actuator 52, will gradually travel through the lines over the course of several upstream-downstream movements of piston 56 until the air bubble A reaches either upstream entrance 702 or downstream entrance 704 of the bleed bore 706. On entry of the air bubble A through a port 702, 704, the bubble A will continue to travel either upstream U or downstream D until it passes entirely through the bore 706 and eventually travels out the terminus 503 of the fluid lines 501 , 502 or into the reservoir 500 where the bubble A exhausts to ambient air and is purged from the system.

[62] In the bleed bore embodiment shown in Figs. 4-9, the floating pin 76 is moved upstream U out of blocking engagement with downstream port 704 when the hydraulic fluid is pumped into the downstream chamber 56d thus enabling the air bubble to enter the bore and eventually travel upstream U through the upstream port 702 and out of the system as described above. As can be readily imagined, the pin is driven downstream D to a position shown in Figs. 5, 8 when the fluid driven into upstream chamber 56u on the down cycle of the process, the downstream port 704 being blocked against fluid flow therethrough when the pin 76 is so driven. The cross-sectional diameter of the cylindrical bleed bore 706 of the Figs. 6-8 embodiments is selected to be slightly larger than the cross-sectional diameter of the cylindrical pin 76 such that flow of fluid through bore 706 around the outer surfaces of pin 76 will be restricted by the narrowness of the space between the outer surface of pin 76 and the inner surface of bore 706 when the pin 76 is in an upstream position as shown for example in Figs. 6, 7, 9 when the fluid is being pumped into downstream chamber 56d.

[63] Similarly for all of the other embodiments shown and described, when the pin 708 is driven to the downstream position shown in Fig. 3C by downstream D drive of the actuator 56, fluid flow is stopped through the downstream port 704 by virtue of the mating of complementary surface 708cs with complementary surface 706ps. Similarly when the outer surface of ball 712 is driven downstream D to a position as shown for example in Fig. 13, the outer surface of ball 712 is complementary to and mates with the complementary surface 706ps and closes off downstream port 704 from flow of fluid or air bubble A.