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WO1991013741A1 - Procede et appareil de moulage par injection avec filtrage du bain de fusion - Google Patents

Procede et appareil de moulage par injection avec filtrage du bain de fusion Download PDF

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Publication number
WO1991013741A1
WO1991013741A1 PCT/JP1990/001301 JP9001301W WO9113741A1 WO 1991013741 A1 WO1991013741 A1 WO 1991013741A1 JP 9001301 W JP9001301 W JP 9001301W WO 9113741 A1 WO9113741 A1 WO 9113741A1
Authority
WO
WIPO (PCT)
Prior art keywords
injection
melt
valve
screw plunger
nozzle passage
Prior art date
Application number
PCT/JP1990/001301
Other languages
English (en)
Inventor
Shigeru Tsutsumi
Original Assignee
Seiki Corporation
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from PCT/JP1990/000300 external-priority patent/WO1991005651A1/fr
Application filed by Seiki Corporation filed Critical Seiki Corporation
Priority to AU67143/90A priority Critical patent/AU6714390A/en
Priority to PCT/JP1990/001503 priority patent/WO1992005939A1/fr
Priority to AU70799/91A priority patent/AU7079991A/en
Priority to PCT/JP1991/000089 priority patent/WO1992005940A1/fr
Priority to JP3503160A priority patent/JPH06506405A/ja
Priority to CA002070425A priority patent/CA2070425A1/fr
Priority to US07/859,721 priority patent/US5246660A/en
Priority to DE69110269T priority patent/DE69110269T2/de
Priority to EP91902786A priority patent/EP0504406B1/fr
Priority to PT97995A priority patent/PT97995A/pt
Priority to CS912052A priority patent/CS205291A3/cs
Priority to CN91104917A priority patent/CN1060621A/zh
Publication of WO1991013741A1 publication Critical patent/WO1991013741A1/fr
Priority to CN94104786A priority patent/CN1097373A/zh
Priority to HK31696A priority patent/HK31696A/xx

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/20—Injection nozzles
    • B29C45/24—Cleaning equipment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
    • B29C45/47—Means for plasticising or homogenising the moulding material or forcing it into the mould using screws
    • B29C45/50—Axially movable screw
    • B29C45/52—Non-return devices

Definitions

  • the present invention relates to an improved and apparatus for injection molding of plastic materials with melt filtration thereof.
  • prior arts including the above U.S. patent incorporate melt filtering devices provided in a nozzle detachably connected to a barrel forming a body of the injection machine.
  • the filtering device comprises a tubular member having a plurality of round 30 or elongated perforations formed therethrough in a parallel and .spaced relation.
  • the perforated tubular member is disposed in or connected to the nozzle so that the perforations communicate with the nozzle.
  • such a melt 35 filtering device or means is provided with a means for purging the impurities accumulated upstream of, but in the vicinity of, the perforations, as needed.
  • a purging operation for example, is performed with the melt including the accumulated impurities discharged out of an outlet of the nozzle without passing through the perforations. This requires detachment of the nozzle with the barrel from a mold arrangement defining the mold cavity, and thus requires a relatively long period of time to reset up the injection molding machine for a normal injection molding operation.
  • the conventional melt filtering device has an inherent problem in that it is subjected to a high pressure loss or exhibits a high pressure resistance against a hot plasticized material, as called "melt" in the process of injection.
  • a high pressure loss due to the filtration is increased as filtration performance is increased and also as an injection rate or speed is increased.
  • the filtration performance relys on a size of the perforations.
  • an injection molding apparatus comprising a mold arrangement, including a cavity mold and a hot runner mold and/or a manifold, and an injection machine having the nozzle, is required to be subjected to a high fluid pressure loss or exert an injection pressure, for
  • melt filtering means is likely to operate with an injection rate lower (for example, 60 to 65 g/sec) than that (for example, 70 g/sec) of the same apparatus but with melt filtering nozzle means provided.
  • an injection rate lower for example, 60 to 65 g/sec
  • melt filtering nozzle means provided.
  • a first object of the present invention is to provide a process and apparatus for injection molding of plastic material with improved melt filtration for removing possible impurities contained in a plasticized material, which melt filtration is effected with no substantial increase in driving power for injection relative to a case where no melt filtration is effected.
  • a second object of the present invention is to provide a process and apparatus for injection molding of plastic material with improved melt filtering means which facilitates purging of accumulated impurities out of the machine system, and also removing impurities clogging the filtering means therefrom, resulting in increased long run productivity due to a decreased period of time during which temporary stopping of the operational run is effected for the purging and/or the removing and then for resetting the apparatus for normal injection molding operation. Both the purging and removing processes can be performed without substantially disassembling any part of the apparatus.
  • a process of injection molding with melt filtration using an injection machine having a body provided with an injection plunger therein and a hollow extension, comprising a nozzle, therefrom forming a nozzle passage, and a mold arrangement defining a cavity, the mold arrangement incorporated with the machine to communicate between the interior of the machin-e body and the mold cavity via the nozzle passage.
  • the process comprises the steps of: having a plastic material, in every shot cycle, plasticized and metered while being heated within the machine body; having the hot plasticized material injected under pressure for the mold cavity through the nozzle passage; and having the hot injected material held at least partially within the entire mold cavity under pressure while the mold arrangement is being cooled to thereby provide and freeze a molded article therein.
  • the process is characterized in that the plasticizing and metering step is carried out such that the plasticized material is subjected to the melt filtration during the metering, and the injecting step is carried out with the filtered and metered material.
  • the above characterizing feature may be applied in a universality used non-pressure-holding chamber system where the nozzle passage is kept open to the barrel after the injecting step, and the pressure-holding is effected by a screw plunger of the injection machine per se.
  • the nozzle passage is inter- rupted midway therealong from communication between the interior of the machine body and the mold cavity, after the injection step but while the material pressure- holding step is being carried out; and upon or after the nozzle passage interruption, the plasticizing and metering step is carried out by the injection machine for a next shot or injection with the plasticized material subjected to the melt filtration during the pressure-holding step.
  • the third kind of system is an improvement from the above second kind of system, and is disclosed in an International Application (in English) No.
  • an injection machine for carrying out plasticizing, metering and injecting steps of injection molding with a plastic material supplied therein, comprising a machine body forming a cylindrical barrel provided with a heating means, a nozzle connected thereto and a screw plunger therein of a rod form with a herical screw thereabout for rotation and axially reciprocating movements.
  • the screw plunger has a tip head portion and a main screw portion with a check valve therebetween.
  • the check valve comprises a movable annular valve body member and a stationary circumferential valve seat member, and is provided to be opened for allowing a plasticized material to flow forwardly therethrough during the plasticizing and metering step where the screw plunger is allowed to move rearwardly against a back pressure with a metered material being accumulated in an axially variable space downstream of the tip head portion defined by the nozzle, the barrel and the screw plunger, and to be closed for allowing the screw plunger to push the entire amount of the accumulated material forwardly toward said nozzle in the injection step.
  • the machine is charac ⁇ terized in that means for effecting a melt filtration while the plasticized material is subjected to the metering is provided in the machine body and incorporated with the check valve.
  • the melt filtering means comprises the valve member having circumferentially arranged perforations for the filtering and being mounted to the screw plunger between the valve body member and the main screw portion.
  • the perforations are positioned to communicate with both an annular valve passage of the check valve between a rod section of the screw plunger and the annular valve body member of a solid form and a plasticizing space defined between the main screw plunger portion and the barrel therein in which space the plastic material is plasticized.
  • the melt filtering means may comprise: the annular valve body member having circumferentially arranged perforations for the filtration and being axially slidably mounted to the screw plunger; and the circumferential valve seat member of a solid form being fixed to the screw plunger and slidably fitted to an internal surface of the barrel.
  • the perforated valve body member is slidably fitted to both the internal barrel surface and an peripheral rod surface of the screw plunger with the perforations allowing the plasticized material to pass therethrough to thereby have the material pass over the check valve at an opened position thereof.
  • it further comprises a radially extending through-hole or purging hole formed in a cylindrical wall of said barrel and a plug to be detachably connected thereto.
  • the purging hole is located in a axial position so that it opens to a local zone of the interior of the barrel in the vicinity of a rear face of the perforated member, when the screw plunger is in the most forward position, in order to have a portion of the plasticized material, with non-filtered impurities or residual foreign materials accumulated on the perforated rear face, in the local space discharged therefrom, intermittently during a long run operation, through the purging hole by rotating the screw plunger in the most forward position.
  • the perforations may be either of a round shape cross section or an elongated shape cross section.
  • the melt filtering means of the present invention incorporated therein is more meritorious than that incorporated in the universal non-pressure-holding system in that the former case enables the valve means for interrupting the nozzle passage to be utilized so that the filtering means being clogged with impurities is released from the clogging, that is the impurities are removed from the filtering means, by effecting a quasi-injection operation while the nozzle passage interruption is effected intentionally, whereas in the latter case such a releasing process as above cannot be performed since no corresponding nozzle passage interruption is ever effected.
  • such a quasi-injection operation may be instantaneous and can also be repeated.
  • Figure 1 is a cross-sectional diagram showing an injection molding apparatus of an internal pressure- holding chamber system incorporated with a melt filtering means according to the present invention
  • Fig. 2 is a plan view of a perforated disk forming the melt filtering means, seen in a direction A in Fig. 1;
  • Fig. 3 is a cross-sectional diagram corresponding to Fig. 1, showing another injection molding apparatus of an internal pressure-holding chamber system and a remetering system in combination with a melt filtering means according to the present invention, and
  • Fig. 4 is a cross-sectional view of a portion of an injection molding apparatus corresponding to those shown in Figs. 1 and 3, showing an embodied combination of a check valve and a melt filtering means according to the present invention.
  • each apparatus for injection molding of plastic material has a conventional single barrel type injection machine 1 and a mold arrangement 10 incorporated therewith.
  • the machine 1 is axially movable for a suck-back operation and for injection, plasticizing and metering operations, and comprises a body forming a cylindrical barrel 2 having a screw plunger 3 therein, a hydraulic piston-cylinder (not shown) with a piston connected to the plunger 3, and a cylindrical hollow extension 20 extending forwardly from the barrel 2.
  • the apparatus further comprises a hot runner ' mold 13 incorporated with a manifold.
  • the hot runner mold 13 is incorporated in the mold arrangement 10 in a thermal-insulating manner involving an air spacer 13a and solid spacer 13b.
  • the cylindrical extension 20 is in direct contact with the hot runner mold 13 at its forward end, but is connected with the mold arrangement 10 at its forward end via a solid thermal insulator 13c.
  • the mold arrangement 10 comprises a stationary mold half 11 and a movable mold half 12.
  • the stationary mold half 11 is connected to the hot runner mold 13.
  • Both mold halves have cooling means 14 and 15, and define at least one cavity 10a for a molded article, which cavity has at least one gate 10b.
  • the gate 10b has a pointed heat-generating module 16, such as a so called “spear", received therein to thereby have the module heat a cold part of the material at the gate temporarily and instantaneously with the effect that the gate is opened to the cavity for a next shot, after the suck-back step is completed.
  • the hot runner mold 13 and the module 16 incorpo ⁇ rated therewith result in a runnerless article being molded.
  • the cylindrical hollow extension 20 is divided into three parts, that is, a forward part 21 connected to the hot runner mold 13, an intermediate piston part 22 axially disposed in the forward part, and a rear part 23.
  • the rear part 23 forms a head portion of the barrel 2, and the intermediate piston part 22 forms a so called “nozzle” detachably connected to the head barrel portion 23.
  • the cylindrical extension 20 is designed so that its hollow space has an enlarged diameter portion 20A, and is provided with band heaters 25 at its periphery.
  • the hot runner mold 13 and the cylindrical extension 20 of the machine 1 in combination form a hollow extension defining a nozzle passage Y communi ⁇ cating the interior of the barrel 2 with the cavity gate 10b.
  • the rear cylindrical extension part 23 is incorpo- rated with a valve means 40.
  • the nozzle passage Y forms an internal pressure-holding chamber X between the valve means 40 and the cavity gate 10b.
  • the intermediate piston part 22 of the cylindrical extension 20, as the "nozzle”, consists of a cylindrical body and a circumferential flange 22a provided to work as a stopper against the forward part 21 at an abutting end face thereof, and also as a sealing means for preventing leakage of the hot material when the material is injected.
  • An axial position of the nozzle 22 relative to the forward part 21 is fixed when the flange 22a abuts against the abutting end face of the forward part 21.
  • the machine 1 with the nozzle 22 is sucked back by a predetermined stroke from the above position. Referring to Figs.
  • the valve means 40 comprises a driving means, for example, a pulse motor (not shown) mounted on the rear cylindrical part 23, and a circular valve rod 42 extending vertically from the motor.
  • the rear part 23 has a vertically circular hole 30 crossing the nozzle passage Y.
  • the valve rod 42 is rotatably disposed in the vertical hole 30, and has a horizontal through-hole 42a.
  • the valve hole 42a forms a portion of the nozzle passage Y when the valve means 40 or the valve rod 42 is in an opened position.
  • the valve rod 42 effects a nozzle passage interruption or a chamber closing against communication of the barrel 2 with the cavity 10a, when it is in a closed position.
  • valve means 40 Immediately after a plasticized and metered material (melt) is injected from the barrel 2 using the screw plunger 3 toward the mold cavity 10a through the nozzle passage Y, the valve means 40 is forced to a closed position by the pulse motor to effect the nozzle passage interruption and to thereby have a closed space z, consisting of the mold cavity 10a and the chamber X, fixed in volume. As a result, most of the injected material is compacted in the closed and fixed space Z to thereby exert an internal pressure against the melt filled in the mold cavity 10a, which pressure is called an "internal holding pressure".
  • a conventional pressure-holding chamber system (not shown) comprises a piston-cylinder device in association with a corresponding chamber X'. Upon a corresponding nozzle passage interruption, the piston-cylinder exerts an external pressure against the melt in a corresponding space Z' which is not fixed but variable in volume.
  • the conventional pressure-holding chamber system may be called an
  • Both kinds of the pressure-holding chamber systems incorporated in the injection molding apparatuses have a common advantage relative to a universal non-pres ⁇ sure-holding chamber system where a holding pressure is exerted by an injection machine per se with a screw plunger.
  • the common advantage resides in that a period of one shot cycle is considerably shortened, leading to an increased productivity. This is because, while an external or internal pressure-holding step is performed, the injection machine is allowed to perform a plasti ⁇ cizing and metering step for a next shot. Therefore, it is preferable to perform such plasticizing and metering step upon the nozzle passage interruption which is to be effected immediately after an injection step in order to minimize a period of one shot cycle in a continuing cyclic injection molding run.
  • the universal non-pressure-holding chamber system where an external pressure-holding is performed by an injection machine per se using a screw plunger for use in the- plasticizing and metering and the injection, is substantially equivalent to the external pressure- holding chamber system in that the pressure-holding relys on an external hydraulic driving source such as the injection machine (in the non-pressure-holding chamber system) or the additional piston-cylinder device (in the external pressure-holding system), and thus the external driving source is likely to cause the weight of a molded product to be varied due to an inevitable pressure variation occurring with the external holding pressure effected.
  • an external hydraulic driving source such as the injection machine (in the non-pressure-holding chamber system) or the additional piston-cylinder device (in the external pressure-holding system)
  • the internal pressure-holding chamber system is advantageous relative to both the above systems in that such a pressure variation as the above does not occur during the internal pressure- holding operation, and thus variation in the weight of a molded product is considerably decreased.
  • the internal pressure-holding chamber system can be used effectively in production of precision molded products with high productivity.
  • the first embodiment as shown in Fig. 1 has no other valve means other than the valve means 40, in association with the internal pressure-holding chamber X.
  • the head barrel portion 23 is provided with a remetering means associated with the first mentioned valve means 40.
  • the remetering means comprises a pressure-sensitive check valve 50 of a valve seat type in association with the first valve means 40.
  • the valve rod 42 of the first valve means 40 has a groove 42b formed at its surface portion.
  • the head barrel portion or the rear part 23 has an outlet hole 30a extending horizontally therefrom to open to the vertical hole 30 in such a position that the groove 42b communicates with both the chamber X and the check valve 50, when the first valve means 40 is in the closed position, and when the first valve means 40 is in the opened position, the horizontal outlet hole 30a is closed by the valve rod 42.
  • the check valve 50 comprises a cylindrical valve chamber 51, having a vertical or radial opening (not shown) for discharging the melt out of the system, a piston valve body 52 of a seat type, and means 53 for urging or biasing the valve body against the melt in the chamber X at a predetermined pressure.
  • the biasing means 53 comprises an inner rod 53a abutting against the valve body 52, an outer rod 53b, coil spring 53c encircling both the rods and sandwiched by the rods, inner and outer threaded housing cylinders 53d and 53e screwed to each other to form a housing for the spring and rods, and a load cell or pressure sensor 53f connected to a free end of the outer housing cylinder
  • a force of the spring 53c is adjusted by screwing the outer housing cylinder 53e relative to the inner housing cylinder 53d.
  • the load cell 53f is provided to detect the spring force or the predetermined pressure for the remetering.
  • the piston valve body 52 has a circumferential chamfered edge at its free end, which edge is to be forced by the spring 53c to abut against a counterpart circumferential outlet edge of the horizontal hole 30a.
  • the second valve means 50 When the first valve means 40 is in the closed position and if the melt pressure is over the predetermined valve, the second valve means 50 is forced by the melt pressure to be in the opened position against the force of the coil spring 53c to thereby allow an excess part of the melt in the space Z to be discharged out of the machine system through the above mentioned passage route until the remaining part ' of the melt in the space Z is balanced with or reduced to the predetermined pressure exerted by the coil spring 53c.
  • the melt compacted in the space Z upon the nozzle passage interruption which is effected by the first valve means 40 immediately after injection, is regulated to a predetermined pressure or metered to a predetermined amount (mass) with a possible excess part of the melt being discharged out of the system.
  • the above compacted melt is metered once in the barrel 2 in cooperation with the screw plunger 3 and then injected through the nozzle passage Y toward the mold cavity 10a.
  • the second valve means may be called the "remetering means”.
  • the remetered melt in the fixed and closed space Z consisting of the mold cavity 10a and the chamber X exerts an internal holding pressure against the mold cavity 10a.
  • a non-remetered melt compacted in a corresponding space Z exerts a corresponding internal holding pressure as previously stated.
  • the remetering and internal pressure-holding chamber system as shown in Fig. 3 is advantageous, relative to the non-remetering internal pressure-holding system as shown in Fig. 1, in that an amount of the melt injected and compacted in the space Z, which amount is likely- to vary due to an operational variation in the metering in every shot cycle, is remetered or regulated to a predetermined level so that the resultant or remetered melt, remaining in the space Z, has a reduced amount of variation.
  • each of the first and second embodied apparatuses as shown in Figs. 1 and 3 has a melt filtering means 60 provided in the machine body, not the nozzle connected thereto, for filtering a plasticized material during the metering in the barrel 2 (the first metering relative to the second metering or remetering in the second embodiment).
  • the screw plunger 3 is of a conventional rod form with a herical screw thereabout, and has a tip head portion 3a, a main screw portion 3b and an intermediate portion 3c therebetween.
  • the tip head portion 3a has an enlarged diameter local portion defining an annular space gap with the barrel 2 therebetween. This space gap allows the melt to flow over the tip head portion 3a into a forward spacial portion 2a therethrough.
  • the intermediate plunger portion 3c in combination with the tip head plunger portion 3a of a cone shape converging in an axially forward direction, forms a check valve 70 of a valve seat type which prevents metered melt from flowing back or rearwardly in the injection step.
  • the check valve 70 comprises a valve chamber defined by the barrel 2, the tip head portion 3a, a rod portion of the intermediate plunger portion 3c and a valve seat member 61 of a disk form connected to the plunger rod 3b'and a valve body member 71 of an annular form axially slidable in the valve chamber.
  • the melt filtering means 60 comprises the valve seat member 61, which has circumferentially arranged perforations 62 of a round cross-sectional shape, and is slidably fitted to an inner surface of the barrel 2 so that the melt is allowed to flow forwardly through only the perforations 62.
  • the annular valve body member 71 is also slidably fitted to the barrel inner surface with an annular space gap between the valve body member 71 and the plunger rod portion, which space gap forms a valve passage. The valve passage is closed when the valve body member 71 closes the filtering perforations 62 of the valve seat member 61 with the valve body member 71 abutting against the valve seat member 61.
  • the tip head portion 3a has a stopper for stopping a forward movement of the valve body member ⁇ - t an d it in combination with the valve body member defines several outlet openings communicating with the valve passage.
  • the perforations 62 of the valve seat member 61 may be called as "valve inlet openings", which communicate with the valve passage only when the check valve 70 is in an opened position.
  • the check valve 70 of the present invention is provided to be opened for allowing a plasticized material or melt to flow forwardly therethrough, while a plasticizing and metering step is carried out with the screw plunger 3 being forced to rotate and move rearwardly against a back pressure by an increasing part of the melt which has passed through the check valve 70 and accumulated in the forward spacial portion 2a, a so called “metering chamber” .
  • the metering chamber 2a is variable in volume, and is defined by the tip head portion 3a, the check valve 70, the valve rod 42 of the first valve means 40 within both the nozzle passage and the interior of the barrel 2. That is, the metering chamber 2a is followed by the internal pressure-holding chamber X, and is increased in volume as the amount of the accumulated melt is increased. This accumulation is the so called “metering”, which is carried out over a predetermined rearward stroke of the rotating and axially withdrawing screw plunger.
  • the check valve 70 is in a closed position, while the screw plunger 3 is in an injecting operation.
  • the valve body member 71 is forced to abut at its rear end against the disk member or valve seat member 61 by the melt pressure, which is equivalent to an injection pressure, to thereby close the perfora- tions 62 of the disk member 61.
  • the conventional main screw portion 3b of the plunger 3 is an axially extending plunger rod 3'b having a screw projection extending radially from a periphery of the plunger rod 3'b and extending helically about the plunger rod 3'b over its entire length.
  • the melt filtering means 60 further comprises an impurity purging means.
  • the purging means comprises a through-hole 63 formed in a cylindrical wall of the barrel 2 to extend horizontally as shown in Figs. 1 and 3, and open to the atmosphere, and a threaded plug 64 to be detachably screwed into the purging hole 63.
  • the purging hole 63 is located in an axial position so that it opens to a local zone of a plasticizing space in the vicinity of a rear face of the perforated disk member 61 when the screw plunger with the disk member fixed thereto is in the most forward position as shown in Fig. 1.
  • the screw plunger is forced to rotate, while it is axially fixed, to thereby have non-filtered or residual impurities or foreign materials accumulated on the rear face of the disk member discharged out of the machine system through the purging hole 63.
  • This purging operation is performed intermittently during a long run operation, as needed.
  • the perforated disk member 61 With the perforated disk member 61, it is pref ⁇ erable to have a peripheral portion 61a extending radially from a level of a periphery of the plunger rod 3'b, which peripheral portion 61a has a conical face as the rear face, converging in a rearward direction as shown in Fig. 1 and being exposed to the plasticizing space, with a helical groove 62b formed thereon as shown in Fig. 2.
  • the perforations 62 are arranged in the helical groove 62b therealong, and the purging hole 63 is located in the vicinity of a periphery of the conical rear face when the screw plunger 3 with the disk member 61 in the most forward position as shown in Fig. 1, where the screw plunger is prevented from moving forward any further by a stopper provided in the machine.
  • the perforations 62 may be designed to be as small in size as 0.7mm or less and as low in number as 36 or less.
  • the filtering means 60 for use in association with the metering occurring in the machine body, or the barrel 2, as shown in Figs. 1 and 3, is advantageous in that it enables the purging operation to be performed while an injection molding apparatus is kept together as a unit without being separated into two parts at the nozzle 22 contrary to the case of the prior art, and thus interruption of the injection molding run for the purging of the accumulated impurities is allowed to be shortened considerably in time, in comparison with the prior art case.
  • the internal pressure-holding system is advantageous in that it can perform an injection molding with high productivity in not only a short run but also in a long run where the impurity purging is effected intermittently, compared with the universal non-chamber system incorporating the conventional filtering device.
  • the filtering means of the present invention mounted to the screw plunger is advantageous in the following aspects.
  • the electric energy required to operate the injection molding apparatus is substantially the same as that required to operate a conventional apparatus involving a filtering means mounted to not the screw plunger but a nozzle located downstream of the metering chamber.
  • a braking performance of the screw plunger against an inertial movement thereof to be exhibited due to the flow resistance of the melt having a high viscosity when the driving of the screw plunger for rotation is stopped, or switched off, is enhanced with the effect that a rearward braking stroke of the screw plunger is decreased with considerably less stroke variation, compared with an apparatus with no such filtering means connected to the screw plunger.
  • This reduced braking stroke variation results in more accurate metering of the melt to be injected in every shot cycle, leading to a reduced weight variation of -a mold product, which is desired for molding a precision product.
  • an injecting power required to attain the same high injection rate (for example, 70 g/sec) is equivalent to that required in a non-filtering apparatus, whereas a filtering apparatus having a nozzle incorporated with a filtering device requires a greater injecting power to attain the same high injecting rate.
  • the filtering of the present invention is advantageous, since it does not require such an increased injecting power to attain a desired high injection rate as in the above case.
  • impurities clogging the perforated disk member 61 can be easily released from the perforated filtering member in the pressure-holding chamber system by performing the following process without disassembling the apparatus.
  • the releasing operation can be performed as follows.
  • the valve means 40 is intentionally closed so that the nozzle passage interruption is effected and during the intentional nozzle passage interruption a quasi-metering operation is performed to some extent and then is intentionally changed to a quasi-injecting operation with the effect that a metered melt in the metering chamber limited by the valve means 40 at.
  • the impurities clogging the disk member 61 are forced to be subjected to the above rearward pressure which is high but lower than a normal injection pressure, during a very short period of time at least until the check valve 70 is closed with the valve body member 71 abutting against the perforated valve seat disk member 61 at the forward face thereof.
  • the impurities accumulated in a local zone facing the rear face of the perforated disk member 61 can be purged with some part of the melt in the plasticizing space in the barrel 2 through the purging hole 63 as needed.
  • the purging is effected by rotating the screw plunger 3 at the most forward axial position thereof, while the purging hole 63 is opened. It is preferable to carry out the above-mentioned impurity removing process and the purging process in this order.
  • the purging process can be carried out in a considerably short period of time without disassembling any part of the apparatus except for the plug 64 being removed from the purging hole 63. In this connection, reduction of the working ratio or productivity in a long molding run due to the purging process being repeated as needed is suppressed or considerably improved in comparison with that in the case of the conventional melt filtration occurring at the nozzle during the injection step.
  • Fig. 4 shows another embodiment of an injection molding apparatus, which is different from the apparatuses shown in Figs. 1 and 3 in only the following features.
  • the apparatus as shown in Fig. 4 has a check valve 70' comprising; a circumferential solid or non-perforated disk member 61' providing a valve seat; a perforated movable annular member 71' forming a valve body; and a section of a screw plunger 3.
  • the valve body 71' is slidably contacted with or fitted to an internal circumferential surface of a barrel 2 and a peripheral rod surface of the plunger section so that it is axially movable relative to the screw plunger section.
  • the disk member 61' is fixed to the screw plunger and defines an annular space gap between the barrel and its periphery.
  • the valve body 71' has an annular groove 72 axially extending in a rearward direction from a forward surface of the valve body, and many axial perforations 62' for melt filtration open to both the annular groove 72 and a rear surface of the valve body forming an abutting face against the valve seat.
  • the disk member 61' has a forwardly extending circumferential projection 61' A which provides the valve seat of a circumferential form and defines an - annular recess about the screw plunger.
  • the valve seat or circumferential projection 61' A is positioned so that it can abut against a peripheral or outer portion of the rear valve body surface and the annular recess can cover all of the perforations 61' with a local space zone 74, when the check valve 70' is in a closed position, to thereby have the valve body perforations 61'interrupted from communicating with a plasticizing space defined between the barrel 2 and a main screw portion of the screw plunger.
  • This design of the annular valve seat projection 61' A relative to the valve body perforations 62' is intended not to have the filtering perforations 62' closed directly by the annular projection 61' A.
  • a tip head portion 3a of the screw plunger 3 forms a stopper for stopping a forward axial movement of the valve body 71' .
  • This stopper and notched grooves formed in a peripheral surface of the valve body at a forward end thereof define several outlet openings 73' of the check valve 70'. In an opened position, the check valve 70' allows the melt to flow forwardly from the plasticizing space to a metering chamber through the perforations 62' and the outlet openings 73' .
  • the difference between the apparatuses shown in Fig. 4 and Fig. 1 or 3 resides in that the former apparatus incorporates the check valve 70' which is designed to have the perforated valve body member 71' exert a melt filtering function, whereas the latter apparatus is designed to have the perforated valve seat member 61 exert the same melt filtering function.
  • the apparatus having the filtering check valve 70' as shown in Fig. 4 has the same advantages as those of Figs. 1 and 3, but is more advantageous in comparison with an apparatus as shown in Fig. 1 or 3 as well as with a conventional injection molding apparatus provided with no filtering check valve in that the perforated filtering valve body 71' of Fig.
  • the check valve 70' causes the check valve 70' to be closed quickly upon the screw plunger 3 commencing a forward axial movement for injection.
  • an operational period of time from the opened position to the closed position is decreased or shortened.
  • This quick closing action taken by the perforated valve body 71' improves an injection operation of the screw plunger, so that a weight variation of a molded product is considerably reduced.
  • the check valve 70' having the perforated filtering valve body 71' is more preferable for use in producing a precision molded article in a long run with high productivity. This preference is enhanced with the internal pressure- holding chamber system as shown in Fig. 1 or 3 being incorporated with the check valve 70' as shown in Fig. 4.
  • the apparatus with the check valve 70' incorporated therein as shown in Fig. 4 has a purging hole 63 and a plug 64 corresponding to those of the apparatus shown in Fig. 1 or 3.
  • the corresponding purging hole 63 is axially positioned so that it opens to the local space zone 73 in the vicinity of the rear surface of the perforated valve body 71' between the valve body and the non-perforated valve seat member 61', when the screw plunger is in the most forward position with the check valve being in the opened position.
  • the melt with impurities accumulated on the rear perforated surface of the valve body 71' can be discharged out of the machine system through the purging hole 63 by rotating the screw plunger at the most forward position thereof .

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

Un procédé et un appareil de moulage par injection de matières plastiques comprennent un dispositif amélioré à perforations de filtrage du bain de fusion, formé d'une soupape de retenue (70) agencée dans un corps de la machine et dont la fonction est de filtrer un matériau plastifié ou un bain de fusion pendant une opération de dosage associée à une opération de plastification, avant l'opération d'injection, de manière à ne pas affecter la vitesse élevée d'injection pendant l'opération d'injection. Ce dispositif amélioré de filtrage du bain de fusion permet d'éliminer les impuretés qui s'accumulent sur sa face postérieure sans détacher la buse, à travers un orifice de purge (63) ménagé dans le corps (2) de la machine. En outre, un système à chambre externe ou interne de maintien de la pression permet d'obtenir une productivité élevée lors du moulage par injection. Ce système comprend une soupape (40) qui bloque le passage de la buse. Le dispositif de filtrage du bain de fusion peut se libérer des impuretés qui l'obstruent par une opération de quasi-injection effectuée pendant que le passage de la buse est bloqué.
PCT/JP1990/001301 1990-03-07 1990-10-06 Procede et appareil de moulage par injection avec filtrage du bain de fusion WO1991013741A1 (fr)

Priority Applications (14)

Application Number Priority Date Filing Date Title
AU67143/90A AU6714390A (en) 1990-10-06 1990-11-16 Process and apparatus for injection molding with melt filtration
PCT/JP1990/001503 WO1992005939A1 (fr) 1990-10-06 1990-11-16 Procede et dispositif de moulage par injection avec filtrage de la matiere en fusion
EP91902786A EP0504406B1 (fr) 1990-10-06 1991-01-28 Appareil de moulage par injection avec filtration et melange de la matiere en fusion
US07/859,721 US5246660A (en) 1990-10-06 1991-01-28 Process and apparatus for injection molding with melt filtration and mixing
PCT/JP1991/000089 WO1992005940A1 (fr) 1990-10-06 1991-01-28 Procede et appareil de moulage par injection avec filtration et melange de la matiere en fusion
JP3503160A JPH06506405A (ja) 1990-10-06 1991-01-28 メルトロ過と混合を伴う射出成形法と装置
CA002070425A CA2070425A1 (fr) 1990-10-06 1991-01-28 Procede et appareil de moulage par injection avec dispositif de filtation et de melange
AU70799/91A AU7079991A (en) 1990-10-06 1991-01-28 Process and apparatus for injection molding with melt filtration and mixing
DE69110269T DE69110269T2 (de) 1990-10-06 1991-01-28 Vorrichtung zum spritzgiessen mit filtration und mischen der schmelze.
PT97995A PT97995A (pt) 1990-10-06 1991-06-17 Processo e aparelho para fundicao injectada com filtragem e mistura do material fundido
CS912052A CS205291A3 (en) 1990-10-06 1991-07-03 Process of injection moulding with a filtering and agitating of a melt and apparatus for making the same
CN91104917A CN1060621A (zh) 1990-10-06 1991-07-16 带熔融料过滤与混合的注射成型的方法和设备
CN94104786A CN1097373A (zh) 1990-10-06 1994-05-04 带熔融料过滤与混合的注射成型的方法和设备
HK31696A HK31696A (en) 1990-10-06 1996-02-22 Apparatus for injection molding with melt filtration and mixing

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JPPCT/JP90/00300 1990-03-07
PCT/JP1990/000300 WO1991005651A1 (fr) 1989-10-12 1990-03-07 Procede et appareil ameliores de moulage a injection du type a chambre sous pression

Publications (1)

Publication Number Publication Date
WO1991013741A1 true WO1991013741A1 (fr) 1991-09-19

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Application Number Title Priority Date Filing Date
PCT/JP1990/001301 WO1991013741A1 (fr) 1990-03-07 1990-10-06 Procede et appareil de moulage par injection avec filtrage du bain de fusion

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Country Link
AU (1) AU6514490A (fr)
WO (1) WO1991013741A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118124086A (zh) * 2024-05-06 2024-06-04 恩格尔注塑机械（常州）有限公司 一种注塑机喷涂装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2524746A1 (de) * 1975-06-04 1976-12-16 Gerhard Prof Dr Ing Schenkel Kunststoff-spritzgiessmaschine mit schneckenplastifizierung und massefilter
DE2541738A1 (de) * 1975-09-19 1977-03-24 Werner & Pfleiderer Spritzgiessmaschine zum verarbeiten plastischer massen
FR2324443A1 (fr) * 1975-09-17 1977-04-15 Netstal Ag Maschf Giesserei Dispositif de plastification pour machines a moulage par injection de matiere plastique
WO1990003879A1 (fr) * 1988-10-13 1990-04-19 Seiki Corporation Co., Ltd. Procede et appareil de moulage par injection

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2524746A1 (de) * 1975-06-04 1976-12-16 Gerhard Prof Dr Ing Schenkel Kunststoff-spritzgiessmaschine mit schneckenplastifizierung und massefilter
FR2324443A1 (fr) * 1975-09-17 1977-04-15 Netstal Ag Maschf Giesserei Dispositif de plastification pour machines a moulage par injection de matiere plastique
DE2541738A1 (de) * 1975-09-19 1977-03-24 Werner & Pfleiderer Spritzgiessmaschine zum verarbeiten plastischer massen
WO1990003879A1 (fr) * 1988-10-13 1990-04-19 Seiki Corporation Co., Ltd. Procede et appareil de moulage par injection

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118124086A (zh) * 2024-05-06 2024-06-04 恩格尔注塑机械（常州）有限公司 一种注塑机喷涂装置

Also Published As

Publication number Publication date
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