CA2019707A1 - Injection molding apparatus with direct gas connection to valve member - Google Patents
Injection molding apparatus with direct gas connection to valve memberInfo
- Publication number
- CA2019707A1 CA2019707A1 CA 2019707 CA2019707A CA2019707A1 CA 2019707 A1 CA2019707 A1 CA 2019707A1 CA 2019707 CA2019707 CA 2019707 CA 2019707 A CA2019707 A CA 2019707A CA 2019707 A1 CA2019707 A1 CA 2019707A1
- Authority
- CA
- Canada
- Prior art keywords
- valve member
- gas
- nozzle
- injection molding
- supply line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Landscapes
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A valve gated gas assisted apparatus having a hollow elongated valve member. A stream of pressurized gas flows from the forward end of the valve member. The stream of gas is surrounded by pressurized melt as it flows through the gate into the cavity to form a hollow product. The pressurized gas is received through a gas supply line which is connected directly to the rear end of the valve member. The gas supply line is sufficiently flexible to allow the valve member to reciprocate continuously. In one embodiment, the gas supply line has a loop to provide additional flexability.
A valve gated gas assisted apparatus having a hollow elongated valve member. A stream of pressurized gas flows from the forward end of the valve member. The stream of gas is surrounded by pressurized melt as it flows through the gate into the cavity to form a hollow product. The pressurized gas is received through a gas supply line which is connected directly to the rear end of the valve member. The gas supply line is sufficiently flexible to allow the valve member to reciprocate continuously. In one embodiment, the gas supply line has a loop to provide additional flexability.
Description
2 ~
IN31e CTIO~ ~OLDI~IG APPARATllS ~ITEI DIRIECT
GAS (::O~E~CTIOL~ TO ~J~L~ Hl~B131R
BACKGROUND OF THE INVENTION
1 This invention relates generally to injection molding and more particularly to valve gated gas assisted apparatus for making plastic products having a hollow or gas filled central portion.
Providing a flow of gas along with the pressurized melt to form hollow plas~ic produc~s is known in the art and is generally referred to as l'gas assisted injection moldingnO An early example is shown in U.S, patent number 4,101,617 to Friederich which issued July 18, 1978O More recent arrangements are shown in European patent application serial number 09360tl89 to Engel Maschinenbau GOmOb3HO published March 28 t 1990 and U.S, : , ~ , -- ~0~7~7 patent number 4,917,594 to Gellert which issued April 17, 1990. It is very desirable for many applications that these systems be valve gated, but the previous valve gated gas assisted systems have had the disadvantage that relatively complicated arrangements have been necessary to supply the gas to the reciprocating valve pin or member.
This has increased the manufacturing cost and resulted in malfunctions during use.
"~ ' 10 SUMMARY OF THE_INVENTION
Accordingly, it is an object of the invention to at least partially overcome the problems of the prior art by providing valve gated gas assisted injection molding apparatus having a flexible gas supply line connected directly to the valve member~
To this end, in one of its aspects, the invention provides valve gated gas assisted injection molding apparatus having a heated nozzle with a rear end, the nozzle being seated in a well in a cavity plate wi.th the rear end abutting against a heated manifold, a melt passage extending to convey pressurized melt from an inlet in the manifold to a gate extending through the cavity plate to a cavity, the nozzle having a central bore extending therethrough~ an elongated valve member having a forward end and a rear end being received in the central .. : ., : :., 2~7~7 1 bore of the nozzle whereby a portion of the melt passage extends in the central bore around a forward portion of the valve member, and valve member actuating means to reciprocate the valve member between a retracted open position and a forward closed position in which the forward end of the valve member is seated in the gate, the improvement wherein the elongated valve member has a hollow central passage extending therethrough, to the forward end of the valve member, a flexible gas supply line being connected to the valve member to supply pressurized gas to the central passage according to a predetermined cycle to provide during injection, a stream of gas from the forward end of the valve member flowing through the gate into the cavity, with melt from the portion of the melt passage around the valve member flowing around the stream of gas into the cavity.
Further objects and advantages of the invention will appear from the following description, taken toge~her with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional view of a portion of a valve gated injection molding system according to one embodiment of the invention showing the melt passage;
- :` 2~7~7 1 Figure 2 is a sectional view taken along line 2-2 in Figure 1 showing the valve member actuating mechanism;
Figure 3 is a similar partial view showing the valve member in the closed position;
Figure 4 is a partial isometric view of the valve member according to this embodiment of the invention;
Figure 5 is a sectional view of a portion of an injection molding system according to another embodiment of the invention; and Figure 6 is a sectional view of a por~ion of Figure 5 showing the piston in the open position.
DETAILED DESCRIPTION OF THE DRAWI~GS
Reference is first made to Figures 1 to 3 which shows a valve gated gas assisted injection molding system or apparatus having a melt passage 10 which extends from a central inlet 12 in a manifold 14, through a central bore 16 of a heated nozzle 18 and a ga~e 20 to a cavity 22~ In this embodiment the melt passage 10 branches from the central inlet 12 into two channels 24 around the valve member actuating mechanism and rejoins in a valve member bushing 26 which is seated in the nozzle 18. ~s can be seen, a portion 27 of the melt passage 10 extends towards ... . ~ . . .
-' 2 ~ 7 ~ 7 1 the gate 20 along a valve member 28 in the central bore 16 which is considerably larger in diameter than the valve member 28.
The nozzle 18 is seated in a well 30 in the cavity plate 32 by an insulation flange or bushing 34 which abuts against a circumferential shoulder 36. This accruately locates the nozzle 18 with the central bore 16 in alignment with the gate 20 and provides an insulative air space 38 between the nozzle 18 and the surrounding cavity plate 32. The nozzle 18 has an electrical heating element 40 which is integrally cast into it and the cavity plate 32 is cooled by pumping cooling water through cooling conduits 42. An injection molding nozzle seal 44 as described in Gellert's U.S. patent number 4,286,941 which issued September 1, 1981 is seated in the nose portion 46 of the nozzle 18 and bridges the air space 38 around the gate 20 to prevent the air space 38 filling with melt.
The manifold 14 is secured in correct alignment to the nozzle 18 by bolts 48. The nozzle 18 and manifold 14 are in turn held in place by a locating ring 50 which is secured by bolts 52 extènding through the support plate 54 into the cavity plate 32.
The valve member bushing 26 i5 securely seated in an opening 56 in the rear end 58 of the nozzle 18 and -- \
-i 2~l9~7 ' ' "',' 1 has a valve member bore 60 extending therethrough in alignment with the central bore 16 through the nozzle 18. As described in UOS~ patent number 4,433,969, the valve member bore 60 which extends into a rearwardly projecting portion 62 of the valve pin bushing 26 is of sufficient length and fits snugly enough around the valve member 28 to seal against leakage of the pressurized melt :
around the valve member 28 as it reciprocates. As can be :
seen, the valve member bushing 26 is shaped to connect the -two channels 24 of the melt passage 10 to the central bore 16 through the nozzle 18. The valve member bushing 26 and the opening 56 in which it is seated in the nozzle 18 are oblong shaped to accurately align it, and the rearwardly projecting portion 62 has two outwardly facing flat surfaces 64.
The elongated valve member 28 has a hollow passage 66, a rear end 68 and a forward end 70 which seats in the gate 20 in the forward closed position. As seen in Figure 4, in this embodiment, the rear end 68 of the valve : 20 member 28 has an enlarged connector portion 72 with a threaded opening 74 to receive a fitting 76 from a flexible gas supply line 78. The valve member 28 also has an enlarged flange portion 80 which is spaced from the connector portion 72. The flange portion 80 has a flat face 82 which is aligned with a flat face 84 of the connector portion 72.
1 The manifold has an electrical heating element 86 which is integrally brazed into it and has a radial opening 88. The slot 88 receives the rearwardly projecting portion 62 of the valve member bushing 26 and a r`ack member 90. The rack member 90 has two inwardly facing flat surfaces 92 which slid against the outwardly acing flat surfaces 64 of the rearwardly projecting portion 62 of the bushing 26. The valve member 28 extends through a groove 94 in the rack member 90, with the enlarged flange portion 80 being engageably received in a transverse slot 96. The rack member 90 also has a toothed portion 98 with a row of outwardly facing teeth 100. The opening 88 in the manifold 14 extends radially outward to receive a pinion lever member 102 which is pivotally ~ ;:
mounted on a pivot pin 104 which extends into the manifold .
14 on opposite sides of the opening 88. The pinion member 102 also has teeth 106 which engage the teeth 100 of the rack member 90 and a pivot lever arm 108 which extends ;~
outwardly through the mouth 110 of the opening 88. The pivot lever arm 108 is connected by a rod 112 to a double- ~ :
acting piston 114 which is driven by air received through hoses (not shown) leading to connectors 116 to reciprocate in a pivotally mounted cylinder 118. While the pivot ;
lever arm 108 is curved in this embodiment to match the location of the cylinder 118 and piston 114, other ~ -~. .. " . , 2 ~ ~ ~ 7 1i~ 7 1 suitable arrangements can be used to drive the pinion lever member 102.
In use, the system is assembled as shown and electrical power is applied to the heating elements 40,86 to heat the manifold 14 and the nozzle 18 to a predetermined operating temperature. Pressurized melt from a molding machine (not shown~ is introduced into the melt passage 10 through the central inlet 12 and a pressurized gas such as nitrogen or air is applied through gas supply line 78 according to a predetermined cycle.
Controlled pneumatic pressure is applied to the cylinder 118 to operate the piston 114 according to a matching cycle. When the piston 114 pivots the pinon lever member 102 to the open position shown in Figure 3 the rack member 90 and the valve member 28 slide rearwardly to withdraw the forward end 70 from the gate 20. Then, injection melt pressure and gas pressure are applied. This produces a stream 120 of gas which flows from the forward end 70 of the valve member 28 through the gate 20 into the cavity 22 with melt from the adjacent portion 27 of the melt passage 10 flowing around it. As seen in Figure 2, this produces a melt bubble 122 which expands until it contacts the walls of the cavity 20. After there is a build up of gas pressure in the filled cavity 20, the piston 114 drives the pinion lever member 102 and the valve member to the . , ., , , . :
,~
2 ~ 1lL 9 7 0 7 1 forward closed position shown in Figure 1 in which the forward end 70 of the valve member 28 is seated in the gate 20. Injection pressure is then released, and after a short cooling period, the gas pressure is released and a suction can be briefly applied so the walls do not blow when the mold is opened. The forward end 70 of the valve member has a porous portion 124 which is formed by - : , sintering stainless steel powder. This allows the gas to ~ -flow outward to the cavity 22, while preventing the melt from flowing back in to plug the hollow passage 66. The mold is then opened along the parting line 126 to eject the hollow molded product. After ejection, the mold is closed and hydraulic pressure is reapplied to the cylinder 118 to withdraw the valve member 28 to the open position ;~
and injection and gas pressure are reapplied to refill the ~ ~
cavity 22. This oycle is repeated continuously with a -frequency dependent upon the size of cavity and type of material being molded. As seen in Figures 2 and 3, in ,:
this embodiment, the gas supply line 78 has several loops 2Q 128 in it to provide additional flexability for its connection to the valve member 28 which reciprocates ~-between the open and closed positions.
Figures 5 and 6 illustrates an injection molding system according to another embodiment of the invention. ~ -The elements of this embodiment which are common to the ,,",, 10 2 ~ 7 . ':
1 first embodiment described above are described and illustrated using the same reference numerals. In this case, the nozzle 18 is similarly seated in well 30 in the cavity plate 32. However, in this embodiment, the valve member actuating means is a piston 130 which reciprocates in a cylinder 132, rather than the rack and pinion mechanism described above. The cylinder 132 is seated in a back plate 134 and hydraulic pressure is applied through hydraulic fluid lines 136 to reciprocate the piston 130 according to a predetermined cycle. The piston 130 has a neck portion 138 which extends through a V-shaped hydraulic seal 140. The piston also has central bore 142 which is threaded adjacent the rear end to receive the ;
valve member 28.
The elongated valve member 28 has a hollow central passage 66 extending from the forward end to the rear end 68. While the forward end is not shown, it is the same as that described above in the first embodiment. In this embodiment, the valve member 28 has an enlarged connector portion 72 which extends through an opening 144 through a cap 146 which is screwed into the cylinder 132. Another hydraulic seal 148 is seated in the cap 146 to prevent leakage of hydraulic fluid as the valve member 28 reciprocates. An L-shaped connector fitting 150 is screwed into an opening 152 in the rear of the connector portion 72 to connect to the gas supply line 78.
- 2~ 7~7 1 In this embodiment of the invention, the heated nozzle 18 is one of several nozzles in a multi-cavity system. The melt passage 10 extends through an elongated manifold 154 having an integral heating element 156. The melt passage 10 extends diagonally through the valve member bushing 26 to join the central bore of the nozzle 18 as described in U.S. patent number 4,433,969 to Gellert which issued February 2B, 1984.
The operatlon cf this embodiment is similar to that described above in regard to the first embodiment- ;
with the valve member 28 being actuated by the piston 130 to which it is connected. As seen in Figure 6, in this embodiment, the gas supply line 78 does not have any loops. If the line 78 is made of a suitable flexible material such as braided high pressure hydraulic hose and it is long enough, it has been found to have sufficient flexability to provide for the continuous movement of the valve member 28.
While the description of the valve gated gas assisted injection molding system has been provided with regard to preferred embodiments, it is not to be construed in a limiting sense. Variations and modifications will occur to those skilled in the art. For instance, the gas `~
supply line 78 can have a single longitudinal loop to provide the necessary flexibility. The forward end 70 of --: 2~7~7 .
1 the valve member 28 can have a number of laser cut holes instead of porous portion 124. Reference is made to the appended claims for a definition of the invention.
.,.. ' ,~ - ~
IN31e CTIO~ ~OLDI~IG APPARATllS ~ITEI DIRIECT
GAS (::O~E~CTIOL~ TO ~J~L~ Hl~B131R
BACKGROUND OF THE INVENTION
1 This invention relates generally to injection molding and more particularly to valve gated gas assisted apparatus for making plastic products having a hollow or gas filled central portion.
Providing a flow of gas along with the pressurized melt to form hollow plas~ic produc~s is known in the art and is generally referred to as l'gas assisted injection moldingnO An early example is shown in U.S, patent number 4,101,617 to Friederich which issued July 18, 1978O More recent arrangements are shown in European patent application serial number 09360tl89 to Engel Maschinenbau GOmOb3HO published March 28 t 1990 and U.S, : , ~ , -- ~0~7~7 patent number 4,917,594 to Gellert which issued April 17, 1990. It is very desirable for many applications that these systems be valve gated, but the previous valve gated gas assisted systems have had the disadvantage that relatively complicated arrangements have been necessary to supply the gas to the reciprocating valve pin or member.
This has increased the manufacturing cost and resulted in malfunctions during use.
"~ ' 10 SUMMARY OF THE_INVENTION
Accordingly, it is an object of the invention to at least partially overcome the problems of the prior art by providing valve gated gas assisted injection molding apparatus having a flexible gas supply line connected directly to the valve member~
To this end, in one of its aspects, the invention provides valve gated gas assisted injection molding apparatus having a heated nozzle with a rear end, the nozzle being seated in a well in a cavity plate wi.th the rear end abutting against a heated manifold, a melt passage extending to convey pressurized melt from an inlet in the manifold to a gate extending through the cavity plate to a cavity, the nozzle having a central bore extending therethrough~ an elongated valve member having a forward end and a rear end being received in the central .. : ., : :., 2~7~7 1 bore of the nozzle whereby a portion of the melt passage extends in the central bore around a forward portion of the valve member, and valve member actuating means to reciprocate the valve member between a retracted open position and a forward closed position in which the forward end of the valve member is seated in the gate, the improvement wherein the elongated valve member has a hollow central passage extending therethrough, to the forward end of the valve member, a flexible gas supply line being connected to the valve member to supply pressurized gas to the central passage according to a predetermined cycle to provide during injection, a stream of gas from the forward end of the valve member flowing through the gate into the cavity, with melt from the portion of the melt passage around the valve member flowing around the stream of gas into the cavity.
Further objects and advantages of the invention will appear from the following description, taken toge~her with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional view of a portion of a valve gated injection molding system according to one embodiment of the invention showing the melt passage;
- :` 2~7~7 1 Figure 2 is a sectional view taken along line 2-2 in Figure 1 showing the valve member actuating mechanism;
Figure 3 is a similar partial view showing the valve member in the closed position;
Figure 4 is a partial isometric view of the valve member according to this embodiment of the invention;
Figure 5 is a sectional view of a portion of an injection molding system according to another embodiment of the invention; and Figure 6 is a sectional view of a por~ion of Figure 5 showing the piston in the open position.
DETAILED DESCRIPTION OF THE DRAWI~GS
Reference is first made to Figures 1 to 3 which shows a valve gated gas assisted injection molding system or apparatus having a melt passage 10 which extends from a central inlet 12 in a manifold 14, through a central bore 16 of a heated nozzle 18 and a ga~e 20 to a cavity 22~ In this embodiment the melt passage 10 branches from the central inlet 12 into two channels 24 around the valve member actuating mechanism and rejoins in a valve member bushing 26 which is seated in the nozzle 18. ~s can be seen, a portion 27 of the melt passage 10 extends towards ... . ~ . . .
-' 2 ~ 7 ~ 7 1 the gate 20 along a valve member 28 in the central bore 16 which is considerably larger in diameter than the valve member 28.
The nozzle 18 is seated in a well 30 in the cavity plate 32 by an insulation flange or bushing 34 which abuts against a circumferential shoulder 36. This accruately locates the nozzle 18 with the central bore 16 in alignment with the gate 20 and provides an insulative air space 38 between the nozzle 18 and the surrounding cavity plate 32. The nozzle 18 has an electrical heating element 40 which is integrally cast into it and the cavity plate 32 is cooled by pumping cooling water through cooling conduits 42. An injection molding nozzle seal 44 as described in Gellert's U.S. patent number 4,286,941 which issued September 1, 1981 is seated in the nose portion 46 of the nozzle 18 and bridges the air space 38 around the gate 20 to prevent the air space 38 filling with melt.
The manifold 14 is secured in correct alignment to the nozzle 18 by bolts 48. The nozzle 18 and manifold 14 are in turn held in place by a locating ring 50 which is secured by bolts 52 extènding through the support plate 54 into the cavity plate 32.
The valve member bushing 26 i5 securely seated in an opening 56 in the rear end 58 of the nozzle 18 and -- \
-i 2~l9~7 ' ' "',' 1 has a valve member bore 60 extending therethrough in alignment with the central bore 16 through the nozzle 18. As described in UOS~ patent number 4,433,969, the valve member bore 60 which extends into a rearwardly projecting portion 62 of the valve pin bushing 26 is of sufficient length and fits snugly enough around the valve member 28 to seal against leakage of the pressurized melt :
around the valve member 28 as it reciprocates. As can be :
seen, the valve member bushing 26 is shaped to connect the -two channels 24 of the melt passage 10 to the central bore 16 through the nozzle 18. The valve member bushing 26 and the opening 56 in which it is seated in the nozzle 18 are oblong shaped to accurately align it, and the rearwardly projecting portion 62 has two outwardly facing flat surfaces 64.
The elongated valve member 28 has a hollow passage 66, a rear end 68 and a forward end 70 which seats in the gate 20 in the forward closed position. As seen in Figure 4, in this embodiment, the rear end 68 of the valve : 20 member 28 has an enlarged connector portion 72 with a threaded opening 74 to receive a fitting 76 from a flexible gas supply line 78. The valve member 28 also has an enlarged flange portion 80 which is spaced from the connector portion 72. The flange portion 80 has a flat face 82 which is aligned with a flat face 84 of the connector portion 72.
1 The manifold has an electrical heating element 86 which is integrally brazed into it and has a radial opening 88. The slot 88 receives the rearwardly projecting portion 62 of the valve member bushing 26 and a r`ack member 90. The rack member 90 has two inwardly facing flat surfaces 92 which slid against the outwardly acing flat surfaces 64 of the rearwardly projecting portion 62 of the bushing 26. The valve member 28 extends through a groove 94 in the rack member 90, with the enlarged flange portion 80 being engageably received in a transverse slot 96. The rack member 90 also has a toothed portion 98 with a row of outwardly facing teeth 100. The opening 88 in the manifold 14 extends radially outward to receive a pinion lever member 102 which is pivotally ~ ;:
mounted on a pivot pin 104 which extends into the manifold .
14 on opposite sides of the opening 88. The pinion member 102 also has teeth 106 which engage the teeth 100 of the rack member 90 and a pivot lever arm 108 which extends ;~
outwardly through the mouth 110 of the opening 88. The pivot lever arm 108 is connected by a rod 112 to a double- ~ :
acting piston 114 which is driven by air received through hoses (not shown) leading to connectors 116 to reciprocate in a pivotally mounted cylinder 118. While the pivot ;
lever arm 108 is curved in this embodiment to match the location of the cylinder 118 and piston 114, other ~ -~. .. " . , 2 ~ ~ ~ 7 1i~ 7 1 suitable arrangements can be used to drive the pinion lever member 102.
In use, the system is assembled as shown and electrical power is applied to the heating elements 40,86 to heat the manifold 14 and the nozzle 18 to a predetermined operating temperature. Pressurized melt from a molding machine (not shown~ is introduced into the melt passage 10 through the central inlet 12 and a pressurized gas such as nitrogen or air is applied through gas supply line 78 according to a predetermined cycle.
Controlled pneumatic pressure is applied to the cylinder 118 to operate the piston 114 according to a matching cycle. When the piston 114 pivots the pinon lever member 102 to the open position shown in Figure 3 the rack member 90 and the valve member 28 slide rearwardly to withdraw the forward end 70 from the gate 20. Then, injection melt pressure and gas pressure are applied. This produces a stream 120 of gas which flows from the forward end 70 of the valve member 28 through the gate 20 into the cavity 22 with melt from the adjacent portion 27 of the melt passage 10 flowing around it. As seen in Figure 2, this produces a melt bubble 122 which expands until it contacts the walls of the cavity 20. After there is a build up of gas pressure in the filled cavity 20, the piston 114 drives the pinion lever member 102 and the valve member to the . , ., , , . :
,~
2 ~ 1lL 9 7 0 7 1 forward closed position shown in Figure 1 in which the forward end 70 of the valve member 28 is seated in the gate 20. Injection pressure is then released, and after a short cooling period, the gas pressure is released and a suction can be briefly applied so the walls do not blow when the mold is opened. The forward end 70 of the valve member has a porous portion 124 which is formed by - : , sintering stainless steel powder. This allows the gas to ~ -flow outward to the cavity 22, while preventing the melt from flowing back in to plug the hollow passage 66. The mold is then opened along the parting line 126 to eject the hollow molded product. After ejection, the mold is closed and hydraulic pressure is reapplied to the cylinder 118 to withdraw the valve member 28 to the open position ;~
and injection and gas pressure are reapplied to refill the ~ ~
cavity 22. This oycle is repeated continuously with a -frequency dependent upon the size of cavity and type of material being molded. As seen in Figures 2 and 3, in ,:
this embodiment, the gas supply line 78 has several loops 2Q 128 in it to provide additional flexability for its connection to the valve member 28 which reciprocates ~-between the open and closed positions.
Figures 5 and 6 illustrates an injection molding system according to another embodiment of the invention. ~ -The elements of this embodiment which are common to the ,,",, 10 2 ~ 7 . ':
1 first embodiment described above are described and illustrated using the same reference numerals. In this case, the nozzle 18 is similarly seated in well 30 in the cavity plate 32. However, in this embodiment, the valve member actuating means is a piston 130 which reciprocates in a cylinder 132, rather than the rack and pinion mechanism described above. The cylinder 132 is seated in a back plate 134 and hydraulic pressure is applied through hydraulic fluid lines 136 to reciprocate the piston 130 according to a predetermined cycle. The piston 130 has a neck portion 138 which extends through a V-shaped hydraulic seal 140. The piston also has central bore 142 which is threaded adjacent the rear end to receive the ;
valve member 28.
The elongated valve member 28 has a hollow central passage 66 extending from the forward end to the rear end 68. While the forward end is not shown, it is the same as that described above in the first embodiment. In this embodiment, the valve member 28 has an enlarged connector portion 72 which extends through an opening 144 through a cap 146 which is screwed into the cylinder 132. Another hydraulic seal 148 is seated in the cap 146 to prevent leakage of hydraulic fluid as the valve member 28 reciprocates. An L-shaped connector fitting 150 is screwed into an opening 152 in the rear of the connector portion 72 to connect to the gas supply line 78.
- 2~ 7~7 1 In this embodiment of the invention, the heated nozzle 18 is one of several nozzles in a multi-cavity system. The melt passage 10 extends through an elongated manifold 154 having an integral heating element 156. The melt passage 10 extends diagonally through the valve member bushing 26 to join the central bore of the nozzle 18 as described in U.S. patent number 4,433,969 to Gellert which issued February 2B, 1984.
The operatlon cf this embodiment is similar to that described above in regard to the first embodiment- ;
with the valve member 28 being actuated by the piston 130 to which it is connected. As seen in Figure 6, in this embodiment, the gas supply line 78 does not have any loops. If the line 78 is made of a suitable flexible material such as braided high pressure hydraulic hose and it is long enough, it has been found to have sufficient flexability to provide for the continuous movement of the valve member 28.
While the description of the valve gated gas assisted injection molding system has been provided with regard to preferred embodiments, it is not to be construed in a limiting sense. Variations and modifications will occur to those skilled in the art. For instance, the gas `~
supply line 78 can have a single longitudinal loop to provide the necessary flexibility. The forward end 70 of --: 2~7~7 .
1 the valve member 28 can have a number of laser cut holes instead of porous portion 124. Reference is made to the appended claims for a definition of the invention.
.,.. ' ,~ - ~
Claims (4)
1. In valve gated gas assisted injection molding apparatus having a heated nozzle with a rear end, the nozzle being seated in a well in a cavity plate with the rear end abutting against a heated manifold, a melt passage extending to convey pressurized melt from an inlet in the manifold to a gate extending through the cavity plate to a cavity, the nozzle having a central bore extending therethrough, an elongated valve member having a forward end and a rear end being received in the central bore of the nozzle whereby a portion of the melt passage extends in the central bore around a forward portion of the valve member, and valve member actuating means to reciprocate the valve member between a retracted open position and a forward closed position in which the forward end of the valve member is seated in the gate, the improvement wherein;
the elongated valve member has a hollow central passage extending therethrough, to the forward end of the valve member, a flexible gas supply line being connected to the valve member to supply pressurized gas to the central passage according to a predetermined cycle to provide during injection, a stream of gas from the forward end of the valve member flowing through the gate into the cavity, with melt from the portion of the melt passage around the valve member flowing around the stream of gas into the cavity.
the elongated valve member has a hollow central passage extending therethrough, to the forward end of the valve member, a flexible gas supply line being connected to the valve member to supply pressurized gas to the central passage according to a predetermined cycle to provide during injection, a stream of gas from the forward end of the valve member flowing through the gate into the cavity, with melt from the portion of the melt passage around the valve member flowing around the stream of gas into the cavity.
2. An injection molding apparatus as claimed in claim 1 wherein the gas supply line is connected to the rear end of the valve member.
3. An injection molding apparatus as claimed in claim 1 wherein the gas supply line has at least one loop leading to the nozzle to provide additional flexability.
4. An injection molding apparatus as claimed in claim 1 wherein the gas supply line extends laterally from the valve member.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2019707 CA2019707A1 (en) | 1990-06-22 | 1990-06-22 | Injection molding apparatus with direct gas connection to valve member |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2019707 CA2019707A1 (en) | 1990-06-22 | 1990-06-22 | Injection molding apparatus with direct gas connection to valve member |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2019707A1 true CA2019707A1 (en) | 1991-12-22 |
Family
ID=4145320
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2019707 Abandoned CA2019707A1 (en) | 1990-06-22 | 1990-06-22 | Injection molding apparatus with direct gas connection to valve member |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2019707A1 (en) |
-
1990
- 1990-06-22 CA CA 2019707 patent/CA2019707A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |