CA1310456C - Extruding apparatus for extruding synthetic resin - Google Patents
Extruding apparatus for extruding synthetic resinInfo
- Publication number
- CA1310456C CA1310456C CA000616031A CA616031A CA1310456C CA 1310456 C CA1310456 C CA 1310456C CA 000616031 A CA000616031 A CA 000616031A CA 616031 A CA616031 A CA 616031A CA 1310456 C CA1310456 C CA 1310456C
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- cylinder
- vent hole
- screw shaft
- extruder
- resin
- Prior art date
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Abstract
A structure of an extruding apparatus for extruding a synthetic resin, including a first extruder and a second extruder having a vent hole, is disclosed. The extruding apparatus includes: a first extruder; and a second extruder having a cylinder with a vent hole, a supply port provided at the proximal end of the cylinder, and connected to a discharge port of the first extruder, a distribution/supply means provided inside the cylinder, having a plurality of passages for fluidically connecting the supply port and a space inside the cylinder, and distributing and supplying a molding material supplied to the supply port into the cylinder, a discharge port provided at the distal end of the cylinder, a screw shaft arranged inside the cylinder, and a motor for driving the screw shaft. An airtight vacuum chamber connected to the vacuum pump is mounted on an outer portion of the vent hole.
Description
~ 1 3 1 0456 ~ 7~-165 EXTRUD[N~ APPARAT~S F~
EXTRUDING SYNTHETIC RESIN
The present invention relates to an extruding apparatus for ex-truding a synthetic resin and, more partieularly, to an extrudiny appara-tus for extruding a synthetic resin, comprising two extruders, a supply port of one of whieh is connected to a diseharge por-t of the other and a vent hole for exhaus-ting by-produet gas.
The present appliea-tion is divided from Canadian Patent Applieation Serial No. 528,808 filed February 3, 1987, the parent application.
A eonventional extruding appara-tus is disclosed in Japanese Patent Disclosure ~Kokai~ No. 48-79864. This extruding apparatus ineludes first and second extruders eaeh having a eylinder whieh has a screw shaft -therein.
The second extruder, located at a front portion, has a single supply port connected to a discharge port of the first extruder, located at a rear portion. The supply port has a sectional area corresponding to the amount of a molding material supplied to the cylinder of the second extruder.
Accordingly, the molding material is softened by the first extruder, at the rear portion, into a semimolten ~5 state, and is supplied into a space between the cylinder and the screw shaft of the second extruder, -through the supply port thereof. However, when the space becomes filled with semimolten resin, a problem occurs at the outer surface of a screw shaft except helical blades or flight of the screw shaft. More specifically, no axial feed effect oeeurs at the outer surfaee of -the shaft, and the semimolten resin beeomes attached to the outer surface of the shaft. The semimolten resin gradually aeeumula-tes on the already attaehed resin, and the seetional area of the spaee between the eylinder and the screw shaft becomes ~31~5~
significantly reduced. In addition, the resin -that has been attached for a long time is removed from the screw shaft and tran~erred to a discharge port. So that a discharge amount of the re~in i~ unstabilized and quality of the extruded resin is degraded.
The second extruder disclosed in Japanese Patent Disclosure (Kokai) No. 48-79864 is provided with a vent hole for exhausting a gas generated when the molding material is melted. This conventional vent hole is situated adjacent to a position in a cylinder where pellet~ used as a molding material are heated and begin to melt, and passes through the cylinder perpendicular thereto. In addition, the vent hole is normally connected directly to a vacuum pump.
However, ~ome of the resin melted near the vent hole is extruded outwardly therefrom, and is drawn by the vacuum pump thereby disturbing the operation of the pump. When the vacuum pump is unable to operate properly, it must then be cleaned by temporarily stopping the operation of the extruder, or else the extruder must be driven by ~witching the vacuum pump to an auxiliary pump which is located in advance during cleaning of the pump, Such a process effectively prevents an extruding operation, and inevitably results in higher operating costs.
The pre~ent invention provides an extruding apparatus for extruding a synthetic resin, that can be continuously driven without the need for it to be periodically stopped.
Continuous operation i~s pos~ible due to the presence of a venting arrangement.
Accordingly, the present invention provides an extruding apparatus comprising a cylinder, a supply port provided at a proximal end of ~aid cylinder, and supplying a re~in molding material into ~aid cylinder, a di.scharge port provided at a distal end of said cylinder, and discharging -the resin moldiny material contained in said cylinder, a screw shaf-t arranged inside said cylinder, and having a helical blade, a motor connected to and driving said screw shaft, a vent hole formed in a side wall portion of said cylinder which a distal end of the helical blade of said screw sha~t opposes when said helical blade moves downward by rotation of said screw shaft, an axis of said vent hole having a predetermined angle wi-th respect to a vertical line, so that an outer end of said vent hole is situated at a higher level than its inner end and wherein the axis of said vent hole is inclined, with respect to a normal line of said screw shaft, at an angle within the range of from 30 to 90 in a direction opposite to a direction of rotation of said screw shaft:
an airtight vacuum chamber connected to said vent hole and mounted on the side wall portion of the cylinder of the extruder including a bottom cover, a top cover and side walls, wherein the vacuum chamber allows gas which is evolved from the semimolten resin molding material to readily be released under a reduced pressure prevalen-t within that chamber, while allowing that resin which enters a vent hole at the time of gas removal and is cured there to be collected within the chamber; and a vacuum pump connected to said airtight vacuum chamber.
This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a plan view, partially in cross section, of a complete extruding apparatus according to the present invention;
Fig. 2 is a vertical sectional view of a second extruder, taken along the line I - I of Fig. 1;
An embodiment of the,present invention will now be described in detail, with re~erence to the accompanying drawings.
. -` t 3 1 0456 As is shown in Fig. 1, an extru~ing apparatus according to the present invention includes first extruder
EXTRUDING SYNTHETIC RESIN
The present invention relates to an extruding apparatus for ex-truding a synthetic resin and, more partieularly, to an extrudiny appara-tus for extruding a synthetic resin, comprising two extruders, a supply port of one of whieh is connected to a diseharge por-t of the other and a vent hole for exhaus-ting by-produet gas.
The present appliea-tion is divided from Canadian Patent Applieation Serial No. 528,808 filed February 3, 1987, the parent application.
A eonventional extruding appara-tus is disclosed in Japanese Patent Disclosure ~Kokai~ No. 48-79864. This extruding apparatus ineludes first and second extruders eaeh having a eylinder whieh has a screw shaft -therein.
The second extruder, located at a front portion, has a single supply port connected to a discharge port of the first extruder, located at a rear portion. The supply port has a sectional area corresponding to the amount of a molding material supplied to the cylinder of the second extruder.
Accordingly, the molding material is softened by the first extruder, at the rear portion, into a semimolten ~5 state, and is supplied into a space between the cylinder and the screw shaft of the second extruder, -through the supply port thereof. However, when the space becomes filled with semimolten resin, a problem occurs at the outer surface of a screw shaft except helical blades or flight of the screw shaft. More specifically, no axial feed effect oeeurs at the outer surfaee of -the shaft, and the semimolten resin beeomes attached to the outer surface of the shaft. The semimolten resin gradually aeeumula-tes on the already attaehed resin, and the seetional area of the spaee between the eylinder and the screw shaft becomes ~31~5~
significantly reduced. In addition, the resin -that has been attached for a long time is removed from the screw shaft and tran~erred to a discharge port. So that a discharge amount of the re~in i~ unstabilized and quality of the extruded resin is degraded.
The second extruder disclosed in Japanese Patent Disclosure (Kokai) No. 48-79864 is provided with a vent hole for exhausting a gas generated when the molding material is melted. This conventional vent hole is situated adjacent to a position in a cylinder where pellet~ used as a molding material are heated and begin to melt, and passes through the cylinder perpendicular thereto. In addition, the vent hole is normally connected directly to a vacuum pump.
However, ~ome of the resin melted near the vent hole is extruded outwardly therefrom, and is drawn by the vacuum pump thereby disturbing the operation of the pump. When the vacuum pump is unable to operate properly, it must then be cleaned by temporarily stopping the operation of the extruder, or else the extruder must be driven by ~witching the vacuum pump to an auxiliary pump which is located in advance during cleaning of the pump, Such a process effectively prevents an extruding operation, and inevitably results in higher operating costs.
The pre~ent invention provides an extruding apparatus for extruding a synthetic resin, that can be continuously driven without the need for it to be periodically stopped.
Continuous operation i~s pos~ible due to the presence of a venting arrangement.
Accordingly, the present invention provides an extruding apparatus comprising a cylinder, a supply port provided at a proximal end of ~aid cylinder, and supplying a re~in molding material into ~aid cylinder, a di.scharge port provided at a distal end of said cylinder, and discharging -the resin moldiny material contained in said cylinder, a screw shaf-t arranged inside said cylinder, and having a helical blade, a motor connected to and driving said screw shaft, a vent hole formed in a side wall portion of said cylinder which a distal end of the helical blade of said screw sha~t opposes when said helical blade moves downward by rotation of said screw shaft, an axis of said vent hole having a predetermined angle wi-th respect to a vertical line, so that an outer end of said vent hole is situated at a higher level than its inner end and wherein the axis of said vent hole is inclined, with respect to a normal line of said screw shaft, at an angle within the range of from 30 to 90 in a direction opposite to a direction of rotation of said screw shaft:
an airtight vacuum chamber connected to said vent hole and mounted on the side wall portion of the cylinder of the extruder including a bottom cover, a top cover and side walls, wherein the vacuum chamber allows gas which is evolved from the semimolten resin molding material to readily be released under a reduced pressure prevalen-t within that chamber, while allowing that resin which enters a vent hole at the time of gas removal and is cured there to be collected within the chamber; and a vacuum pump connected to said airtight vacuum chamber.
This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a plan view, partially in cross section, of a complete extruding apparatus according to the present invention;
Fig. 2 is a vertical sectional view of a second extruder, taken along the line I - I of Fig. 1;
An embodiment of the,present invention will now be described in detail, with re~erence to the accompanying drawings.
. -` t 3 1 0456 As is shown in Fig. 1, an extru~ing apparatus according to the present invention includes first extruder
2 and second extruder 12. First cylinder 4 is provided for extruder 2. First supply port 5 for supplying a molding material into c~linder 4, is provided at the proximal end of cylinder 4. First screw shaft 6 for transferring the molding material supplied from port 5, is arranged inside cylinder 4, and first motor ~ for driving shaft 6 is mounted at the proximal end of extruder 2.
Discharge port 10 is provided a-t the dis-tal end of extruder 2. Extruder 2 includes second cylinder 14, and second supply port 22 for supplying the material into cylinder 14 is provided to the proximal end thereof~
Second screw shaft 16 is arranged inside cylinder 14, and second motor 18 for driving shaft 16 is mounted at the proximal end of extruder 12. Coupling member 20 has first communication passage ~4 for connecting discharge port 10 of cylinder 4 and supply port 22 of cylinder 140 First pressure gage 26 for measuring resin pressure in passage 24 and pressure control valve 28 for controlling the resin pressure to be supplied to extruder 2, are mounted to member 20.
Inner diameter Dl of cylinder 4 of extruder 2 and inner diameter D2 of cylinder 14 of extruder 12 are designed in accordance with the following relationship;
Dl/D2 < 1 and more preferably, in accordance with the following equation;
Dl/D2 = 0.9 to 0.65 For example, when Dl = 100 mm, D2 = about 130 mm.
Extruding port 30 of extruder 12 is coupled to extruding die 32 by connecting member 36 having passage
Discharge port 10 is provided a-t the dis-tal end of extruder 2. Extruder 2 includes second cylinder 14, and second supply port 22 for supplying the material into cylinder 14 is provided to the proximal end thereof~
Second screw shaft 16 is arranged inside cylinder 14, and second motor 18 for driving shaft 16 is mounted at the proximal end of extruder 12. Coupling member 20 has first communication passage ~4 for connecting discharge port 10 of cylinder 4 and supply port 22 of cylinder 140 First pressure gage 26 for measuring resin pressure in passage 24 and pressure control valve 28 for controlling the resin pressure to be supplied to extruder 2, are mounted to member 20.
Inner diameter Dl of cylinder 4 of extruder 2 and inner diameter D2 of cylinder 14 of extruder 12 are designed in accordance with the following relationship;
Dl/D2 < 1 and more preferably, in accordance with the following equation;
Dl/D2 = 0.9 to 0.65 For example, when Dl = 100 mm, D2 = about 130 mm.
Extruding port 30 of extruder 12 is coupled to extruding die 32 by connecting member 36 having passage
3~. Second and third pressure gages 33 and 40 ~or measuring the internal resin pressure are provided near port 30, and are in the middle of second connecting member .
~ . i' ~310~5~
36. Thermometer 42 for measuring mol-ten resin temperature inside passage 34 is provided on mernber 36.
Vent hole 44 for exhausting a gas generate~ when the resin is mel-ted is provided in suppl~ por-tion 46 of extruder 12. More specifically, it is provided in a cylinder side wall, which the distal end of blade or flight 72 of shaft 16 opposes when b:lade 72 moves down~
ward, by way of rotation of shaft 16, in an arrow direc-tion, as is shown in Fig. 2. In this embodiment, hole 44 is provided such that its axis is inclined -to the horizontal or vertical, at about 45, and at the same time, is inclined with reæpect to a normal line of shaft 16, at an angle of 45, in a direction opposite to the direction of rotation of shaf-t 16. However, inclina-tion angle ~, with respect to the normal line of shaf-t 16, may be arbitrarily selected, as long as it falls within 30 to 90.
As is shown in Fig. 2, airtight vacuum chamber 48 is connected to the outer end of hole 44. Chamber 48 is constituted by side wall 52, bottom cover 50, and top cover 62, and has a space 49 which is shielded from the ambient atmosphere. Space 49 is normally set in a vacuum.
Opening 56 of hole 44 is provided in a side wall portion at an upper level, rather than in a middle portion, of chamber 48. Bottom cover 50 is mounted on a bottom portion of side wall 52, to be opened and closed by a suitable fastener 78, such as a bolt. Cooling coils 54 and 55 are attached to the outer surfaces of side wall 52 and bottom cover 50, respectively, and their inner surfaces serve as heat-exchange surfaces for cooling the resin overflowing from hole 44. The heat-exchange surfaces are provided at a predetermined distance below opening 56 of hole 44. On the other hand, pump-connecting port 60, cowpled -to vacuum pump 58, is provided in a side wall portion, at a level above that of opening 56. Top cover 62 for closing an upper opening of chamber I ~ ~ 0456 48 is formed partially of a -transparent material, -this transparent portion serving as a window for external observa-tion of the interior of the airtight vacuum chamber.
The operation of the extruding apparatus will now be described below.
Firs-t, a thermoplas-tic synthetic resin or a mix-ture 25 of this resin and a powder of a filler ma-terial is supplied as a raw material from supply port 5 of first extruder 2. Yirst and second screw shafts 6 and 16 are rotated by motors 8 and 18, respectively, and selectecl portions of cylinders 4 and 14 are heated to a prede-termined temperature, by a conven-tional method. As a result, the resin in a semimolten state, prepared by extruder 2, is discharged from discharge por-t 10, and is supplied, through communica-tion passage 24, to supply port 22 of second extruder 12~ The semimolten resin supplied into the cylinder of extruder 12 is transferred toward the distal end by second screw shaft 16, and is further heated during transfer. ~ gas generated while the resin is passing through cylinder 14 is drawn and exhausted by vacuum pump 58, through vent hole 44 formed to sllpply portion 46, and through airtight vacuum chamber 48.
On the other hand, the molten resin minus the gas, is further mixed by shaft 16. The resultant resin is then supplied -to die 32 from extruding port 30, through passage 34. Upon supply to die 32, the molten synthetic resin is molded into a desired shape.
When the molten resin passes near the inner end of hole 44, a part thereof is extruded into hole 44.
However, since hole 44 is inclined by a predetermined angle, as is shown in Fig. 2, most of the extruded resin returns by its own weight, into cylinder 14, and is then milled again by shaft 16, and mixed with ano-ther portion of resin. Thereafter, the resin is mixed uniformly and supplied -to die 32.
In the apparatus of this embodiment, the amount of resin supplied to die 32 is controlled by the rotational frequency of shaft 16, and the rotational frequency of shaft 6 of extruder 2 is controlled so that the pressure indicated by second pressure gage 38 will be always maintained substantially constant. In addition, pressure control valve 2~ is controlled when needed, to s-tabilize the pressure indicated by gage 38. This control may be manually executed by an operator, while observing the pressure of gage 38 and the amount of molten resin supplied from hole 44 and extruded into the airtight vacuum chamber. Alternatively, an automatic control device provided with a plurality of sensors may be mounted to automatically control the rotational frequency of shaft 6.
Furthermore, in the extruding apparatus according to the present invention, since inner diameter Dl of the cylinder of first extruder 2 is smaller than inner diameter D2 of the cylinder of second extruder 12, extruder 12 is less adversely affected by variations in : the amount of resin extruded from extruder 2. Since the rotational speeds of the respective shafts can be easily and finely controlled, the rotational frequency of the screw sha~t of extruder 2 may be selected to stabilize the pressure, so that the amount of resin extruded from the vent hole can be reduced.
In addition, since the cylinders of the first and second extruders have different diameters, the rotational speed of the screw shaft of the first extruder can be relatively increased. For this reason, the plasticising efficiency and melting efficiency of -the pellets are increased.
'' 1310~5~
On the other hand, the inner diameter of the cylinder of the second extruder is formed larger, and the screw shaft of the second ex-truder is rota-ted more slowly, by about 10 to 50% of that of the screw shaft of the first extruder. Accordingly, the resin transferred inside the cylinder is heated sufficiently by a heater, but is not overheated because of the low rotational speed of the second screw shaft, resulting in less degradation of the resin.
However, when the ratio of the inner diameters of cylinders of two extruders is smaller than that describecl above, almost no above-mentioned effects can be obtained by cylinders having different inner diameters. When the ratio is larger than that described above, the ro-tati.onal frequency of -the screw shaft of the first extruder becomes faster than is needed, thereby adversely affecting the resin.
In this extruding apparatus, when the entire apparatus is operating, the semimolten pelle-ts and the filler material are transferred axially with respect to cylinder 14 and shaft 16, and the gas, produced when the resin is melted, is exhausted through hole 44 during transfer. A part of resin 66 in a molten or semimolten state is extruded into hole 44 as described above, but the resin or the filler material in hole 44 is :orced to return into cylinder 14, by force of gravi-ty, due to hole 44 being inclined aæ shown in Fig. 2. In addition, since hole 44 is inclined, with respect to the normal line of the screw shaft, at a predetermined angle, in a direction opposite to the direction of rotation of the screw shaft, the resin emerging from hole 44 is scraped by blade 72, as shaft 16 rota-tes, thereby most of the remaining resin then returning into cylinder 14.
However, the molten or semimolten resin t.rapped in hole 44 and attached to its inner wall surface gradually -` t 31 045~
g expands, pushes an~ opens normally closed valve 76, and then is extruded into airtigh-t vacuum chamber ~8.
The resin extruded into chamber 48 flows downward, and is stored thereinO At the same time, the gas and the resin are separated, the gas being drawn GUt and removed by pump 5~.
When the resin stored in chamber 48 approaches connecting port 56 of the ven-t hole, pump 58 is tem-porarily stopped to equalize the pressure inside chamber l() 48 with an ambient atmosphere, fastener 78 is loosened to open bottom cover 50, and the solidified resin is removed from chamber 48. Thereafter, cover 50 is closed and fastened by fastener 78, and pump 58 is restarted.
As is described above, in the extruding apparatus of the present invention, the resin extruded from the vent hole is solidified in chamber 48. For this reason, the resin can be easily removed, and the resin extruded into the airtight vacuum chamber can be re-used, because it is almost uncontaminated by a polluted ambient atmosphere.
In addition, the interior of chamber 48 can be easily observed, since top cover 62 includes a transparent portion. Moreover, top and bottom covers 62 and 50 can be opened to facilitate cleaning of the interior of chamber 48.
When inclination angle A of hole 44 is se-t within the range described above, with respect to the normal line of cylinder 14, -the resin supplied into hole 44 can be easily returned to the cylinder. When angle A is set outside the above range, the amount of resin supplied into hole 44 is increased.
When the angle of inclination of hole 44, with respect -to the horizontal, is set to about 45, chamber 48 - lo -- 1 3 1 04 5 6 can be easily mounted thereon, ancl the supplied amount of -the molten resin can be reduced.
As a modification of this embodiment, two such airtight vacuum chamberæ 48 may be provided and moun-ted -to be alternately slid to opening 56 of hole 44. When one of the airti.ght vacuum chambers becomes full of resin, and the resin is to be removed, another airtight vacuum chamber may then be connected to opening 56, replacing the first chamber. Thus, the efficiency of the extruding apparatus can be further increased.
In addition, since a vent hole for exhausting by -produced gas is provided at a portion near the supply port, the surface a.rea of the pelletized semimolten resin is increased near the vent hole, with the result that the gas included therein is completely exhausted out.
~ . i' ~310~5~
36. Thermometer 42 for measuring mol-ten resin temperature inside passage 34 is provided on mernber 36.
Vent hole 44 for exhausting a gas generate~ when the resin is mel-ted is provided in suppl~ por-tion 46 of extruder 12. More specifically, it is provided in a cylinder side wall, which the distal end of blade or flight 72 of shaft 16 opposes when b:lade 72 moves down~
ward, by way of rotation of shaft 16, in an arrow direc-tion, as is shown in Fig. 2. In this embodiment, hole 44 is provided such that its axis is inclined -to the horizontal or vertical, at about 45, and at the same time, is inclined with reæpect to a normal line of shaft 16, at an angle of 45, in a direction opposite to the direction of rotation of shaf-t 16. However, inclina-tion angle ~, with respect to the normal line of shaf-t 16, may be arbitrarily selected, as long as it falls within 30 to 90.
As is shown in Fig. 2, airtight vacuum chamber 48 is connected to the outer end of hole 44. Chamber 48 is constituted by side wall 52, bottom cover 50, and top cover 62, and has a space 49 which is shielded from the ambient atmosphere. Space 49 is normally set in a vacuum.
Opening 56 of hole 44 is provided in a side wall portion at an upper level, rather than in a middle portion, of chamber 48. Bottom cover 50 is mounted on a bottom portion of side wall 52, to be opened and closed by a suitable fastener 78, such as a bolt. Cooling coils 54 and 55 are attached to the outer surfaces of side wall 52 and bottom cover 50, respectively, and their inner surfaces serve as heat-exchange surfaces for cooling the resin overflowing from hole 44. The heat-exchange surfaces are provided at a predetermined distance below opening 56 of hole 44. On the other hand, pump-connecting port 60, cowpled -to vacuum pump 58, is provided in a side wall portion, at a level above that of opening 56. Top cover 62 for closing an upper opening of chamber I ~ ~ 0456 48 is formed partially of a -transparent material, -this transparent portion serving as a window for external observa-tion of the interior of the airtight vacuum chamber.
The operation of the extruding apparatus will now be described below.
Firs-t, a thermoplas-tic synthetic resin or a mix-ture 25 of this resin and a powder of a filler ma-terial is supplied as a raw material from supply port 5 of first extruder 2. Yirst and second screw shafts 6 and 16 are rotated by motors 8 and 18, respectively, and selectecl portions of cylinders 4 and 14 are heated to a prede-termined temperature, by a conven-tional method. As a result, the resin in a semimolten state, prepared by extruder 2, is discharged from discharge por-t 10, and is supplied, through communica-tion passage 24, to supply port 22 of second extruder 12~ The semimolten resin supplied into the cylinder of extruder 12 is transferred toward the distal end by second screw shaft 16, and is further heated during transfer. ~ gas generated while the resin is passing through cylinder 14 is drawn and exhausted by vacuum pump 58, through vent hole 44 formed to sllpply portion 46, and through airtight vacuum chamber 48.
On the other hand, the molten resin minus the gas, is further mixed by shaft 16. The resultant resin is then supplied -to die 32 from extruding port 30, through passage 34. Upon supply to die 32, the molten synthetic resin is molded into a desired shape.
When the molten resin passes near the inner end of hole 44, a part thereof is extruded into hole 44.
However, since hole 44 is inclined by a predetermined angle, as is shown in Fig. 2, most of the extruded resin returns by its own weight, into cylinder 14, and is then milled again by shaft 16, and mixed with ano-ther portion of resin. Thereafter, the resin is mixed uniformly and supplied -to die 32.
In the apparatus of this embodiment, the amount of resin supplied to die 32 is controlled by the rotational frequency of shaft 16, and the rotational frequency of shaft 6 of extruder 2 is controlled so that the pressure indicated by second pressure gage 38 will be always maintained substantially constant. In addition, pressure control valve 2~ is controlled when needed, to s-tabilize the pressure indicated by gage 38. This control may be manually executed by an operator, while observing the pressure of gage 38 and the amount of molten resin supplied from hole 44 and extruded into the airtight vacuum chamber. Alternatively, an automatic control device provided with a plurality of sensors may be mounted to automatically control the rotational frequency of shaft 6.
Furthermore, in the extruding apparatus according to the present invention, since inner diameter Dl of the cylinder of first extruder 2 is smaller than inner diameter D2 of the cylinder of second extruder 12, extruder 12 is less adversely affected by variations in : the amount of resin extruded from extruder 2. Since the rotational speeds of the respective shafts can be easily and finely controlled, the rotational frequency of the screw sha~t of extruder 2 may be selected to stabilize the pressure, so that the amount of resin extruded from the vent hole can be reduced.
In addition, since the cylinders of the first and second extruders have different diameters, the rotational speed of the screw shaft of the first extruder can be relatively increased. For this reason, the plasticising efficiency and melting efficiency of -the pellets are increased.
'' 1310~5~
On the other hand, the inner diameter of the cylinder of the second extruder is formed larger, and the screw shaft of the second ex-truder is rota-ted more slowly, by about 10 to 50% of that of the screw shaft of the first extruder. Accordingly, the resin transferred inside the cylinder is heated sufficiently by a heater, but is not overheated because of the low rotational speed of the second screw shaft, resulting in less degradation of the resin.
However, when the ratio of the inner diameters of cylinders of two extruders is smaller than that describecl above, almost no above-mentioned effects can be obtained by cylinders having different inner diameters. When the ratio is larger than that described above, the ro-tati.onal frequency of -the screw shaft of the first extruder becomes faster than is needed, thereby adversely affecting the resin.
In this extruding apparatus, when the entire apparatus is operating, the semimolten pelle-ts and the filler material are transferred axially with respect to cylinder 14 and shaft 16, and the gas, produced when the resin is melted, is exhausted through hole 44 during transfer. A part of resin 66 in a molten or semimolten state is extruded into hole 44 as described above, but the resin or the filler material in hole 44 is :orced to return into cylinder 14, by force of gravi-ty, due to hole 44 being inclined aæ shown in Fig. 2. In addition, since hole 44 is inclined, with respect to the normal line of the screw shaft, at a predetermined angle, in a direction opposite to the direction of rotation of the screw shaft, the resin emerging from hole 44 is scraped by blade 72, as shaft 16 rota-tes, thereby most of the remaining resin then returning into cylinder 14.
However, the molten or semimolten resin t.rapped in hole 44 and attached to its inner wall surface gradually -` t 31 045~
g expands, pushes an~ opens normally closed valve 76, and then is extruded into airtigh-t vacuum chamber ~8.
The resin extruded into chamber 48 flows downward, and is stored thereinO At the same time, the gas and the resin are separated, the gas being drawn GUt and removed by pump 5~.
When the resin stored in chamber 48 approaches connecting port 56 of the ven-t hole, pump 58 is tem-porarily stopped to equalize the pressure inside chamber l() 48 with an ambient atmosphere, fastener 78 is loosened to open bottom cover 50, and the solidified resin is removed from chamber 48. Thereafter, cover 50 is closed and fastened by fastener 78, and pump 58 is restarted.
As is described above, in the extruding apparatus of the present invention, the resin extruded from the vent hole is solidified in chamber 48. For this reason, the resin can be easily removed, and the resin extruded into the airtight vacuum chamber can be re-used, because it is almost uncontaminated by a polluted ambient atmosphere.
In addition, the interior of chamber 48 can be easily observed, since top cover 62 includes a transparent portion. Moreover, top and bottom covers 62 and 50 can be opened to facilitate cleaning of the interior of chamber 48.
When inclination angle A of hole 44 is se-t within the range described above, with respect to the normal line of cylinder 14, -the resin supplied into hole 44 can be easily returned to the cylinder. When angle A is set outside the above range, the amount of resin supplied into hole 44 is increased.
When the angle of inclination of hole 44, with respect -to the horizontal, is set to about 45, chamber 48 - lo -- 1 3 1 04 5 6 can be easily mounted thereon, ancl the supplied amount of -the molten resin can be reduced.
As a modification of this embodiment, two such airtight vacuum chamberæ 48 may be provided and moun-ted -to be alternately slid to opening 56 of hole 44. When one of the airti.ght vacuum chambers becomes full of resin, and the resin is to be removed, another airtight vacuum chamber may then be connected to opening 56, replacing the first chamber. Thus, the efficiency of the extruding apparatus can be further increased.
In addition, since a vent hole for exhausting by -produced gas is provided at a portion near the supply port, the surface a.rea of the pelletized semimolten resin is increased near the vent hole, with the result that the gas included therein is completely exhausted out.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An extruding apparatus comprising:
a cylinder a supply port provided at a proximal end of said cylinder, and supplying a resin molding material into said cylinder;
a discharge port provided at a distal end of said cylinder, and discharging the resin molding material contained in said cylinder;
a screw shaft arranged inside said cylinder, and having a helical blade;
a motor connected to and driving said screw shaft;
a vent hole formed in a side wall portion of said cylinder which a distal end of the helical blade of said screw shaft opposes when said helical blade moves downward by rotation of said screw shaft, an axis of said vent hole having a predetermined angle with respect to a vertical line, so that an outer end of said vent hole is situated at a higher level than its inner end and wherein the axis of said vent hole is inclined, with respect to a normal line of said screw shaft, at an angle within the range of from 30° to 90° in a direction opposite to a direction of rotation of said screw shaft:
an airtight vacuum chamber connected to said vent hole and mounted on the side wall portion of the cylinder of the extruder including a bottom cover, a top cover and side walls, wherein the vacuum chamber allows gas which is evolved from the semimolten resin molding material to readily be released under a reduced pressure prevalent within that chamber, while allowing that resin which enters a vent hole at the time of gas removal and is cured there to be collected within the chamber; and a vacuum pump connected to said airtight vacuum chamber.
a cylinder a supply port provided at a proximal end of said cylinder, and supplying a resin molding material into said cylinder;
a discharge port provided at a distal end of said cylinder, and discharging the resin molding material contained in said cylinder;
a screw shaft arranged inside said cylinder, and having a helical blade;
a motor connected to and driving said screw shaft;
a vent hole formed in a side wall portion of said cylinder which a distal end of the helical blade of said screw shaft opposes when said helical blade moves downward by rotation of said screw shaft, an axis of said vent hole having a predetermined angle with respect to a vertical line, so that an outer end of said vent hole is situated at a higher level than its inner end and wherein the axis of said vent hole is inclined, with respect to a normal line of said screw shaft, at an angle within the range of from 30° to 90° in a direction opposite to a direction of rotation of said screw shaft:
an airtight vacuum chamber connected to said vent hole and mounted on the side wall portion of the cylinder of the extruder including a bottom cover, a top cover and side walls, wherein the vacuum chamber allows gas which is evolved from the semimolten resin molding material to readily be released under a reduced pressure prevalent within that chamber, while allowing that resin which enters a vent hole at the time of gas removal and is cured there to be collected within the chamber; and a vacuum pump connected to said airtight vacuum chamber.
2. An apparatus according to claim 1, wherein an angle of inclination of said vent hole, with respect to the horizontal line, is set to be 45°.
3. An apparatus according to claim 1, wherein said bottom cover is formed to be opened and closed, said top cover is partially formed of a transparent plate, so that an interior can be observed therethrough.
4. An apparatus according to claim 1, wherein an opening of the outer end of said vent hole is formed in a side wall portion, at a slightly higher level than a middle portion of said airtight vacuum chamber, and a connecting port for communicating with said vacuum pump is formed in a side wall portion, at a higher level than said opening.
5. An apparatus according to claim 1, wherein a cooling coil is mounted on at least one region of the side wall of said airtight vacuum chamber.
6. An apparatus according to claim 1, wherein the cooling coil is mounted on said bottom cover of said airtight vacuum chamber.
7. An extruding apparatus for extruding a synthetic resin, comprising:
a first extruder, having a first cylinder, a first supply port provided at a proximal end of said first cylinder and supplying a resin molding material into said first cylinder, a first discharge port provided at a distal end of said first cylinder, and discharging the resin molding material contained in said first cylinder, a first screw shaft arranged inside said first cylinder, and having a helical blade, and a first motor connected to and driving said first screw shaft;
a second extruder, having a second cylinder, a second supply port, provided at a proximal end of said second cylinder, and supplying the molding material into said second cylinder, a second discharge port, provided at a distal end of said second cylinder, and discharging the resin molding material contained in said second cylinder, a second screw shaft, arranged inside said second cylinder, and having a helical blade, a second motor, connected to and driving said second screw shaft, a vent hole formed in a side wall portion of said second cylinder, which a distal end of the helical blade of said second screw shaft opposes when said helical blade moves downward by rotation of said second screw shaft, an axis of said vent hole having a predetermined angle with respect to a horizontal line, so that an outer end of said vent hole is situated at a higher level than its inner end and wherein the axis of said vent hole is inclined, with respect to a normal line of said screw shaft, at an angle within the range of from 30° to 90° in a direction opposite to a direction of rotation of said screw shaft, an airtight vacuum chamber connected to said vent hole and mounted on the side wall portion of the cylinder of the extruder including a bottom cover formed to he opened and closed, a top cover and side walls, wherein the vacuum chamber allows gas which is evolved from the semimolten resin molding material to readily be released under a reduced pressure prevalent within that chamber, while allowing that resin which enters a vent hole at the time of gas removal and is cured there to be collected within the chamber, a vacuum pump connected to said airtight vacuum chamber; and a coupling member for coupling said first discharge port of said first extruder and said second supply port of said second extruder.
a first extruder, having a first cylinder, a first supply port provided at a proximal end of said first cylinder and supplying a resin molding material into said first cylinder, a first discharge port provided at a distal end of said first cylinder, and discharging the resin molding material contained in said first cylinder, a first screw shaft arranged inside said first cylinder, and having a helical blade, and a first motor connected to and driving said first screw shaft;
a second extruder, having a second cylinder, a second supply port, provided at a proximal end of said second cylinder, and supplying the molding material into said second cylinder, a second discharge port, provided at a distal end of said second cylinder, and discharging the resin molding material contained in said second cylinder, a second screw shaft, arranged inside said second cylinder, and having a helical blade, a second motor, connected to and driving said second screw shaft, a vent hole formed in a side wall portion of said second cylinder, which a distal end of the helical blade of said second screw shaft opposes when said helical blade moves downward by rotation of said second screw shaft, an axis of said vent hole having a predetermined angle with respect to a horizontal line, so that an outer end of said vent hole is situated at a higher level than its inner end and wherein the axis of said vent hole is inclined, with respect to a normal line of said screw shaft, at an angle within the range of from 30° to 90° in a direction opposite to a direction of rotation of said screw shaft, an airtight vacuum chamber connected to said vent hole and mounted on the side wall portion of the cylinder of the extruder including a bottom cover formed to he opened and closed, a top cover and side walls, wherein the vacuum chamber allows gas which is evolved from the semimolten resin molding material to readily be released under a reduced pressure prevalent within that chamber, while allowing that resin which enters a vent hole at the time of gas removal and is cured there to be collected within the chamber, a vacuum pump connected to said airtight vacuum chamber; and a coupling member for coupling said first discharge port of said first extruder and said second supply port of said second extruder.
Applications Claiming Priority (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28183/86 | 1986-02-12 | ||
| JP61028182A JPS62184829A (en) | 1986-02-12 | 1986-02-12 | Vent type extruder |
| JP61028183A JPH0747293B2 (en) | 1986-02-12 | 1986-02-12 | Vent type different diameter two-stage extruder |
| JP28182/86 | 1986-02-12 | ||
| JP27891/86 | 1986-02-13 | ||
| JP61027891A JPH0657421B2 (en) | 1986-02-13 | 1986-02-13 | Two-stage type extruder |
| CA000528808A CA1288921C (en) | 1986-02-12 | 1987-02-03 | Extruding apparatus for extruding synthetic resin |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000528808A Division CA1288921C (en) | 1986-02-12 | 1987-02-03 | Extruding apparatus for extruding synthetic resin |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1310456C true CA1310456C (en) | 1992-11-24 |
Family
ID=27426453
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616031A Expired - Fee Related CA1310456C (en) | 1986-02-12 | 1991-03-22 | Extruding apparatus for extruding synthetic resin |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1310456C (en) |
-
1991
- 1991-03-22 CA CA000616031A patent/CA1310456C/en not_active Expired - Fee Related
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| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |