CA1153519A - Injection molding apparatus for the production of thermoplastic bodies having a continuous skin and a cellular core - Google Patents
Injection molding apparatus for the production of thermoplastic bodies having a continuous skin and a cellular coreInfo
- Publication number
- CA1153519A CA1153519A CA000350017A CA350017A CA1153519A CA 1153519 A CA1153519 A CA 1153519A CA 000350017 A CA000350017 A CA 000350017A CA 350017 A CA350017 A CA 350017A CA 1153519 A CA1153519 A CA 1153519A
- Authority
- CA
- Canada
- Prior art keywords
- passage
- mold
- channel
- slider
- cylinder
- 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.)
- Expired
Links
- 238000001746 injection moulding Methods 0.000 title claims description 7
- 230000001413 cellular effect Effects 0.000 title claims description 5
- 238000004519 manufacturing process Methods 0.000 title claims description 5
- 229920001169 thermoplastic Polymers 0.000 title claims description 5
- 239000004416 thermosoftening plastic Substances 0.000 title claims description 5
- 239000000463 material Substances 0.000 claims description 15
- 229920003002 synthetic resin Polymers 0.000 claims description 6
- 239000000057 synthetic resin Substances 0.000 claims description 6
- 230000000903 blocking effect Effects 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 2
- 241001052209 Cylinder Species 0.000 claims 1
- 238000004891 communication Methods 0.000 abstract description 5
- 238000000465 moulding Methods 0.000 abstract description 5
- 238000002347 injection Methods 0.000 description 7
- 239000007924 injection Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 5
- 238000010348 incorporation Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000002861 polymer material Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000004616 structural foam Substances 0.000 description 2
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
Landscapes
- Moulds For Moulding Plastics Or The Like (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A molding apparatus in which a slider is slidable in an inclined channel into which a passage opens at one side for communication with a mold cavity while a pair of passages open at the opposite side for communication with a plasticating (worm) cylinder and a further cylinder provided with a plunger or piston. The slider has a U-shaped passage, the arms of which are positioned to interconnect both of the passages on the other side of the channel in a position of the slider in which the passage to the mold is blocked but which connects only the accumulating cylinder passage through the bight of the U-shaped passage to the mold in another position of the slider. A check valve is provided in the passage of the worm cylinder.
A molding apparatus in which a slider is slidable in an inclined channel into which a passage opens at one side for communication with a mold cavity while a pair of passages open at the opposite side for communication with a plasticating (worm) cylinder and a further cylinder provided with a plunger or piston. The slider has a U-shaped passage, the arms of which are positioned to interconnect both of the passages on the other side of the channel in a position of the slider in which the passage to the mold is blocked but which connects only the accumulating cylinder passage through the bight of the U-shaped passage to the mold in another position of the slider. A check valve is provided in the passage of the worm cylinder.
Description
3s~
The present invention relates to an injection molding apparatus Eor the production of thermoplastic bodies with a continuous skin and a cellular core, particularly for molding by the gas counter-pressure method, as disclosed in Canadian Patent 1,028460 issued on March 28, 1978, having as inventors Angel Touchev BALEVSKI et al.
There are knowndistributing devices for machines of this type which are used for injection molding by the low-pressure process. In one of them, the foamable polymer melt streams are controlled by a rotating three-position valve or two two-position valves, while in machines for molding by the gas counterpressure method there is also used a distributing device, which is disposed between an accumulating cylinder, the injection mold and the plasticating unit, this device comprising a non-return valve between the plasticating unit and the accumulating cylinder.
A drawback of these known distributing devices for machines of this type lies in that, because of the direct connection between plasticating unit, mold and accumulating cylinder, there is the possibility that not only fresh or virgin plasticated material will be introduced into the mold, but also material already foamed during the previous cycle before the formation of a skin, thus impairing the quality of the latter. Another drawback lies in the necessity of separate devices for the actuation and control of the valves.
herefore, it is a general object of this invention to provide a distributing device for machines for injection molding of thermoplastic bodies with a solid skin and a cellu-! lar core, in which the control unit performs the functions of the known distributing devices without any danger of deterio-ration of the virgin unfoamed polymer, the device to be of compact construction, simply actuated and controlled, and .5~ 9 suitable for incorporation. in different injection molding machines for the production of structural foam bodies by low or high pressure, as well as by the gas counter-pressure method.
According to the present invention there is provided an injection molding apparatus for the production of thermoplastic bodies having a continuous skin and a cellular core, comprising:
a mold having the shape of a body to be produced and provided with a mold cavity formed with an inlet for foamable synthetic resin material; a plasticating unit including a worm and worm cylinder for preparation of said synthetic resin material, the plasticating unit having an outlet spaced from said mold; an accumulating cylinder laterally spaced from and parallel to the cylinder of the plasticating unit and provided with a piston; and a distributing device disposed between the plasti-cating unit, the accumulating cylinder and the mold. The distributing device comprises a distributing body formed with a channel inclined to the axes of the cylinders, means forming a first passage communicating with the inlet and open at one side of the channel, means forming a second passage communi cating with the outlet oE the plasticating unit and opening at a side of the channel opposite the one side, a third passage communicating with the accumulating cylinder and opening at the opposite side of said channel. A two-position slider is shiftable in the channel and is formed with a generally U-shaped passage having respective arms communicating with the second and third passages in one position of the slider in which the slider blocks said first passage. The U-shaped passage has a bight region communicating with the first j 30 passage when one of the arms communicates with the third passage in a second position of the slider blocking the second passage. A check valve is provided in the second passage ~2--~ ~;35~.~
blocking flow of synthetic resin material through the second passage toward the plasticating unit.
The distributing device uses a simple two-position linear motion of the plunger, which allows ready incorporation in the systems for actuation and control of any type of machine for injection mo]ding of structural foam parts, while the U-shaped communication channel provides for the introduc-tion only of virgin polymer material into the mold until the skin is formed, and for the filling-up of the core portion of the molded body with foamed material from the previous cycle only at the end of the molding cycle, since there is no direct connection between the plasticating unit and the mold. More-over, the compactness of the distributing device and the suita-bility for its incorporation in machines or different design contribute to its versatility which, contributes to a greater versatility of the machine, making it possible for them to produce by different processes bodies with smooth and uniformly colored surfaces without swirl patterns and flow marks and, hence, to eliminate the necessity of additional finishing ope-rations such as polishing and painting.
For a better understanding of the invention, reference should be made to the accompanying drawing in which the sole figure is a cross section illustrating a preferred embodiment of the invention.
The illustrated device comprises a body 2 disposed between a warm-type plasticating unit 1, a mold 3 and an accu-mulating cylinder 6, parallel to but laterally spaced from unit 1, a two-position plunger 4, moving inside a blind bore machined at an angle to the direction of injection in body 2, (i.e. at an angle to the axes of the feed passage and units 1 and 6). sody 2 in its one side is shaped as a connector with an injection channel 3a, pressed against mold 3, while at its ~ ~35~ ~
opposite side there are machined two other channels 4a, 4b ending with adjoining surfaces, oriented, with regard to the attachment of body 2 towards the plasticating unit 1 and the accumulating cyoinder 6, in the direction of injectlon.
In an enlarged portion of the channel towards the plasticating unit 1 there is provided a non-return or check valve 5, while the connection of plasticating unit 1 to the accumulating cylinder 6 and of the accumulating cylinder 6 to the mold 3 is effected through a U-shaped communication channel 4c machined in the two-position plunger 4, both ends of this channel being open towards the plasticating unit 1 and the accumulating cylinder 6, respectively, while in its opposite side, this U-shaped channel is open towards the mold 3.
The operation of the distributing device is as follows:
When the pressure inside the plasticating unit 1 is increased above a preset magnitude, the non-return valve 5 is opened and lets through plasticated material, which passes through the U-shaped communication channel 4c, to plunger 4 and into the accumulating cylinder 6 until it fills a preset volume, the plunger 4 being in its upper position, which connects the plasticating unit 1 to the accumulating cylinder 6. After moving the plunger 4 in bottom position, in which the accumulating cylinder 6 is connected to the mold 3, there is provided a possibility for filling the mold 3 with polymer material, as well as for the formation of a cellular core in a solid skin by egression of excess melt into the accumulating cylinder 6 as a result of retraction of the injection ram 7.
At upper position of plunger 4, the injection channel 3a towards the mold is closed and the molded body 2 can be removed.After compression by the injection ram 7 of the excess foamed mate-rial within the accumulating cylinder 6, this material is : -4-~.~L5~S~.9 is pushed towards the front part of the cylinder 6 by the entering virgin material introduced from the ylasticating unit 1 for the next molding cycle; after this, by moving plunger 4 into its bottom position, first virgin material and then compressed foamed material from the previous cycle are fed to the mold by plunger 7.
~;~
The present invention relates to an injection molding apparatus Eor the production of thermoplastic bodies with a continuous skin and a cellular core, particularly for molding by the gas counter-pressure method, as disclosed in Canadian Patent 1,028460 issued on March 28, 1978, having as inventors Angel Touchev BALEVSKI et al.
There are knowndistributing devices for machines of this type which are used for injection molding by the low-pressure process. In one of them, the foamable polymer melt streams are controlled by a rotating three-position valve or two two-position valves, while in machines for molding by the gas counterpressure method there is also used a distributing device, which is disposed between an accumulating cylinder, the injection mold and the plasticating unit, this device comprising a non-return valve between the plasticating unit and the accumulating cylinder.
A drawback of these known distributing devices for machines of this type lies in that, because of the direct connection between plasticating unit, mold and accumulating cylinder, there is the possibility that not only fresh or virgin plasticated material will be introduced into the mold, but also material already foamed during the previous cycle before the formation of a skin, thus impairing the quality of the latter. Another drawback lies in the necessity of separate devices for the actuation and control of the valves.
herefore, it is a general object of this invention to provide a distributing device for machines for injection molding of thermoplastic bodies with a solid skin and a cellu-! lar core, in which the control unit performs the functions of the known distributing devices without any danger of deterio-ration of the virgin unfoamed polymer, the device to be of compact construction, simply actuated and controlled, and .5~ 9 suitable for incorporation. in different injection molding machines for the production of structural foam bodies by low or high pressure, as well as by the gas counter-pressure method.
According to the present invention there is provided an injection molding apparatus for the production of thermoplastic bodies having a continuous skin and a cellular core, comprising:
a mold having the shape of a body to be produced and provided with a mold cavity formed with an inlet for foamable synthetic resin material; a plasticating unit including a worm and worm cylinder for preparation of said synthetic resin material, the plasticating unit having an outlet spaced from said mold; an accumulating cylinder laterally spaced from and parallel to the cylinder of the plasticating unit and provided with a piston; and a distributing device disposed between the plasti-cating unit, the accumulating cylinder and the mold. The distributing device comprises a distributing body formed with a channel inclined to the axes of the cylinders, means forming a first passage communicating with the inlet and open at one side of the channel, means forming a second passage communi cating with the outlet oE the plasticating unit and opening at a side of the channel opposite the one side, a third passage communicating with the accumulating cylinder and opening at the opposite side of said channel. A two-position slider is shiftable in the channel and is formed with a generally U-shaped passage having respective arms communicating with the second and third passages in one position of the slider in which the slider blocks said first passage. The U-shaped passage has a bight region communicating with the first j 30 passage when one of the arms communicates with the third passage in a second position of the slider blocking the second passage. A check valve is provided in the second passage ~2--~ ~;35~.~
blocking flow of synthetic resin material through the second passage toward the plasticating unit.
The distributing device uses a simple two-position linear motion of the plunger, which allows ready incorporation in the systems for actuation and control of any type of machine for injection mo]ding of structural foam parts, while the U-shaped communication channel provides for the introduc-tion only of virgin polymer material into the mold until the skin is formed, and for the filling-up of the core portion of the molded body with foamed material from the previous cycle only at the end of the molding cycle, since there is no direct connection between the plasticating unit and the mold. More-over, the compactness of the distributing device and the suita-bility for its incorporation in machines or different design contribute to its versatility which, contributes to a greater versatility of the machine, making it possible for them to produce by different processes bodies with smooth and uniformly colored surfaces without swirl patterns and flow marks and, hence, to eliminate the necessity of additional finishing ope-rations such as polishing and painting.
For a better understanding of the invention, reference should be made to the accompanying drawing in which the sole figure is a cross section illustrating a preferred embodiment of the invention.
The illustrated device comprises a body 2 disposed between a warm-type plasticating unit 1, a mold 3 and an accu-mulating cylinder 6, parallel to but laterally spaced from unit 1, a two-position plunger 4, moving inside a blind bore machined at an angle to the direction of injection in body 2, (i.e. at an angle to the axes of the feed passage and units 1 and 6). sody 2 in its one side is shaped as a connector with an injection channel 3a, pressed against mold 3, while at its ~ ~35~ ~
opposite side there are machined two other channels 4a, 4b ending with adjoining surfaces, oriented, with regard to the attachment of body 2 towards the plasticating unit 1 and the accumulating cyoinder 6, in the direction of injectlon.
In an enlarged portion of the channel towards the plasticating unit 1 there is provided a non-return or check valve 5, while the connection of plasticating unit 1 to the accumulating cylinder 6 and of the accumulating cylinder 6 to the mold 3 is effected through a U-shaped communication channel 4c machined in the two-position plunger 4, both ends of this channel being open towards the plasticating unit 1 and the accumulating cylinder 6, respectively, while in its opposite side, this U-shaped channel is open towards the mold 3.
The operation of the distributing device is as follows:
When the pressure inside the plasticating unit 1 is increased above a preset magnitude, the non-return valve 5 is opened and lets through plasticated material, which passes through the U-shaped communication channel 4c, to plunger 4 and into the accumulating cylinder 6 until it fills a preset volume, the plunger 4 being in its upper position, which connects the plasticating unit 1 to the accumulating cylinder 6. After moving the plunger 4 in bottom position, in which the accumulating cylinder 6 is connected to the mold 3, there is provided a possibility for filling the mold 3 with polymer material, as well as for the formation of a cellular core in a solid skin by egression of excess melt into the accumulating cylinder 6 as a result of retraction of the injection ram 7.
At upper position of plunger 4, the injection channel 3a towards the mold is closed and the molded body 2 can be removed.After compression by the injection ram 7 of the excess foamed mate-rial within the accumulating cylinder 6, this material is : -4-~.~L5~S~.9 is pushed towards the front part of the cylinder 6 by the entering virgin material introduced from the ylasticating unit 1 for the next molding cycle; after this, by moving plunger 4 into its bottom position, first virgin material and then compressed foamed material from the previous cycle are fed to the mold by plunger 7.
~;~
Claims
1.- An injection molding apparatus for the produc-tion of thermoplastic bodies having a continuous skin and a cellular core, said apparatus comprising:
a mold having the shape of a body to be produced and provided with a mold cavity formed with an inlet for foamable synthetic resin material;
a plasticating unit including a worm and worm cylin-der for preparation of said synthetic resin material, said plasticating unit having an outlet spaced from said mold;
an accumulating cylinder laterally spaced from and parallel to the cylinder of said plasticating unit and provided with a piston; and a distributing device disposed between said plasti- :
cating unit, said accumulating cylinder and said mold, said distributing device comprising:
a distributing body formed with a channel inclined to the axes of said cylinders, means forming a first passage communicating with said inlet and open at one side of said channel, means forming a second passage communicating with said outlet of said plasticating unit and opening at a side of said channel opposite said one side, a third passage communicating with said accumula-ting cylinder and opening at said opposite side of said channel, a two-position slider shiftable in said channel and formed with a generally U-shaped passage having respective arms communicating with said second and third passages in one posi-tion of said slider in which said slider blocks said first passage, said U-shaped passage having a bight region communi-cating with said first passage when one of said arms commu-nicates with said third passage in a second position of said slider blocking said second passage, and a check valve in said second passage blocking flow of synthetic resin material through said second passage toward said plasticating unit.
a mold having the shape of a body to be produced and provided with a mold cavity formed with an inlet for foamable synthetic resin material;
a plasticating unit including a worm and worm cylin-der for preparation of said synthetic resin material, said plasticating unit having an outlet spaced from said mold;
an accumulating cylinder laterally spaced from and parallel to the cylinder of said plasticating unit and provided with a piston; and a distributing device disposed between said plasti- :
cating unit, said accumulating cylinder and said mold, said distributing device comprising:
a distributing body formed with a channel inclined to the axes of said cylinders, means forming a first passage communicating with said inlet and open at one side of said channel, means forming a second passage communicating with said outlet of said plasticating unit and opening at a side of said channel opposite said one side, a third passage communicating with said accumula-ting cylinder and opening at said opposite side of said channel, a two-position slider shiftable in said channel and formed with a generally U-shaped passage having respective arms communicating with said second and third passages in one posi-tion of said slider in which said slider blocks said first passage, said U-shaped passage having a bight region communi-cating with said first passage when one of said arms commu-nicates with said third passage in a second position of said slider blocking said second passage, and a check valve in said second passage blocking flow of synthetic resin material through said second passage toward said plasticating unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000350017A CA1153519A (en) | 1980-04-16 | 1980-04-16 | Injection molding apparatus for the production of thermoplastic bodies having a continuous skin and a cellular core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000350017A CA1153519A (en) | 1980-04-16 | 1980-04-16 | Injection molding apparatus for the production of thermoplastic bodies having a continuous skin and a cellular core |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153519A true CA1153519A (en) | 1983-09-13 |
Family
ID=4116727
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000350017A Expired CA1153519A (en) | 1980-04-16 | 1980-04-16 | Injection molding apparatus for the production of thermoplastic bodies having a continuous skin and a cellular core |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1153519A (en) |
-
1980
- 1980-04-16 CA CA000350017A patent/CA1153519A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |