WO2016113777A1 - 射出成形方法、射出成形機のスクリュ及び射出成形機 - Google Patents
射出成形方法、射出成形機のスクリュ及び射出成形機 Download PDFInfo
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- WO2016113777A1 WO2016113777A1 PCT/JP2015/000167 JP2015000167W WO2016113777A1 WO 2016113777 A1 WO2016113777 A1 WO 2016113777A1 JP 2015000167 W JP2015000167 W JP 2015000167W WO 2016113777 A1 WO2016113777 A1 WO 2016113777A1
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- screw
- mixture
- throttle
- injection molding
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- 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
- B29C45/58—Details
- B29C45/60—Screws
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- 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
- B29C45/0005—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor using fibre reinforcements
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2101/00—Use of unspecified macromolecular compounds as moulding material
- B29K2101/12—Thermoplastic materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
- B29K2105/12—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of short lengths, e.g. chopped filaments, staple fibres or bristles
Definitions
- the present invention relates to injection molding of a resin containing reinforcing fibers.
- Molded products of fiber reinforced resin which has been strengthened by containing reinforced fibers, are used in various applications.
- This molded product is produced by injecting a mixture of a thermoplastic resin and reinforcing fibers melted by the rotation of a screw in a cylinder constituting a plasticizing apparatus into a mold of an injection molding machine.
- Patent Document 1 discloses an injection molding screw in which individually prepared resin raw materials and reinforcing fibers are supplied together at a position corresponding to an upstream screw base to be plasticized and melted. Each of the compression section and the weighing section is owned by a screw, and further mixed at the tip to knead and disperse the molten resin and reinforcing fibers.
- Patent Document 2 provides a raw material compression section in which the shaft diameter is made larger than that of other portions at the screw measurement section or at a position downstream of the screw, and the passage cross-sectional area of the mixture of molten resin and reinforcing fibers is reduced. Propose that. In this raw material compression section, the mixture sent from the upstream side is abruptly compressed to apply a shearing force to promote mixing and dispersion of reinforcing fibers in the molten resin.
- the supplied reinforcing fibers form a bundle and reach the inside of the cylinder. Opening the fiber bundle is important for uniformly dispersing the reinforcing fibers.
- the fiber forming the bundle is crushed and tightly tightened by the resin compression pressure in the compression portion of the screw. Therefore, it is difficult for the fiber bundle to open even if shearing force due to screw rotation and position replacement by tip mixing are added, and the fiber bundle is mixed into the finally obtained molded product. This leads to poor quality.
- the fiber bundle blocks a part of the nozzle injection port, which is a channel having a small diameter, when the mixture is injected toward the cavity of the mold. It becomes a flow resistance.
- the backflow prevention valve has a narrow internal molten resin flow path, so that a fiber bundle with insufficient opening remains in the mixture. If so, there is a possibility that the fiber bundle will block a part of the flow path to cause clogging. In this case, there is a possibility that the plasticizing ability is lowered or a state incapable of plasticizing (unmeasurable) occurs. Furthermore, there is a case where a fiber bundle is caught in the flow path closing portion of the backflow prevention valve at the time of injection, and a flow path failure is generated, preventing the backflow of the mixture to the screw side.
- an object of the present invention is to provide an injection molding method capable of proceeding with the opening even if the fiber is crushed and tightly tightened. Another object of the present invention is to provide an injection molding machine screw and an injection molding machine suitable for such an injection molding method.
- the inventors have made a springback phenomenon for the fiber bundle by reducing the pressure after compressing the mixture of the fiber bundle and the molten resin, and causing a ballast effect for the molten resin.
- the idea was to expand the fiber bundle by kneading by rotating the screw after the expansion. That is, the present invention supplies a solid resin raw material and reinforcing fibers to a cylinder having a screw that can be rotated about a rotation axis and that can be moved forward and backward along the rotation axis.
- a strong compressive force is applied to the mixture of the reinforcing fiber and the molten resin as compared with the upstream side of the throttle region, and then the downstream that has passed through the throttle region.
- the mixture is kneaded by rotating the screw.
- the solid resin raw material and the reinforcing fiber are supplied upstream from the drawing region, and a mixture of the reinforcing fiber and the molten resin may be generated before reaching the drawing region. it can.
- screw, mixture produced is provided on at least a part of the region through, the outer diameter D 2 than the shaft diameter D 1 of the said upstream side of the screw than the partial region and enlarged aperture portion, continuous with the constricted portion at the downstream side, a pressure reducing unit for the shaft diameter D 3 is reduced from the outer diameter D 2 of the throttle section, continuous to the downstream end of the vacuum unit, the kneading section for kneading the mixture
- the throttle region is provided inside the cylinder and around the throttle part, the expansion region is provided inside the cylinder and around the pressure reduction part, and the kneading part is provided inside the cylinder. Thus, it can be provided around the expansion region.
- the screw the ratio of the shaft diameter D 3 to the outer diameter D 2 (shaft diameter D 3 / outer diameter D 2) is preferably 0.5 to 0.95. Also this screw, than the shaft diameter D 1 of the upstream side of the screw than the diaphragm portion, it is possible to reduce the shaft diameter D 3 in the decompression portion.
- the screw of the injection molding machine of the present invention is used to obtain a fiber reinforced resin by injection molding a mixture of a molten resin and a reinforced fiber, and is made by plasticizing and melting a solid resin material. It is provided in the melting part that produces a mixture of resin and reinforcing fibers, and in at least a part of the region through which the produced mixture passes, and the outer diameter is expanded more than the axial diameter of the screw upstream of the part of the region.
- the throttle portion preferably has a ring shape in which the outer diameter is expanded over the entire circumference rather than the axial diameter of the screw.
- the throttle section includes a main flight and a subflight whose outer diameter is set smaller than that of the main flight.
- the subflight has a lead angle larger than that of the main flight, and both ends thereof are the main flight. Is preferably closed.
- the injection molding machine of the present invention is provided in a cylinder provided with a discharge nozzle and inside the cylinder so as to be able to rotate around the rotation axis and to be capable of moving forward and backward along the rotation axis.
- An injection molding machine for injection-molding fiber reinforced resin wherein the screw plasticizes and melts a solid resin material to produce a mixture of molten resin and reinforced fibers, Provided in at least a part of the region through which the mixed mixture passes, and a throttle part having an outer diameter larger than the axial diameter of the screw on the upstream side of the part of the part, and a throttle part on the downstream side. And a kneading part that is connected to the downstream end of the throttle part and kneads the mixture discharged from the throttle part by the rotation of a screw.
- the fiber bundle by reducing the pressure after applying compression, a springback phenomenon is caused in the fiber bundle, and a ballast effect is caused in the molten resin, thereby expanding the mixture and breaking the bundle of the fiber bundle. Thereafter, the fiber bundle can be opened by kneading by rotating the screw.
- FIG. 1 shows schematic structure of the injection molding machine which concerns on this embodiment. It is a figure which shows typically the molten state of the resin in each procedure of the injection molding which concerns on this embodiment, (a) is the time of plasticization start, (b) is the time of completion of plasticization, (c) is the time of completion of injection. Show. (A) is an enlarged view of the vicinity of the throttle portion of the screw shown in FIGS. 1 and 2, (b) shows a springback phenomenon, and (c) shows a ballast phenomenon of the molten resin.
- the screw applicable to this embodiment is shown, (a) shows the example, (b) shows another example, (c) has shown the behavior of the molten resin.
- the injection molding machine 1 includes a mold clamping unit 100, a plasticizing unit 200, and a control unit 50 that controls the operation of these units.
- a mold clamping unit 100 the configuration and operation of the mold clamping unit 100 and the outline of the configuration and operation of the plasticizing unit 200 will be described, and then the procedure of injection molding by the injection molding machine 1 will be described.
- the mold clamping unit 100 is fixed on the base frame 101 and on a sliding member 107 such as a rail or a sliding plate by operating a stationary die plate 105 to which a stationary mold 103 is attached and a hydraulic cylinder 113. And a plurality of tie bars 115 for connecting the fixed die plate 105 and the movable die plate 111 to each other.
- the fixed die plate 105 is provided with a hydraulic cylinder 117 for clamping a die coaxially with each tie bar 115, and one end of each tie bar 115 is connected to a ram 119 of the hydraulic cylinder 117.
- Each of these elements performs a necessary operation in accordance with an instruction from the control unit 50.
- the general operation of the mold clamping unit 100 is as follows. First, the movable die plate 111 is moved to the position of the two-dot chain line in the figure by the operation of the hydraulic cylinder 113 for opening and closing the mold, and the movable mold 109 is brought into contact with the fixed mold 103. Next, the male screw portion 121 of each tie bar 115 and the half nut 123 provided on the movable die plate 111 are engaged to fix the movable die plate 111 to the tie bar 115. Then, the pressure of the hydraulic oil in the oil chamber on the movable die plate 111 side in the hydraulic cylinder 117 is increased, and the fixed mold 103 and the movable mold 109 are tightened. After performing the mold clamping in this way, the molten resin M is injected from the plasticizing unit 200 into the cavity of the mold to form a molded product.
- the screw 10 of this embodiment is a system in which individually prepared thermoplastic resin pellets P and reinforcing fibers F are introduced into a supply hopper 207 provided in the vicinity of the upstream end of the screw 10 and mixed.
- the configuration of the mold clamping unit 100 specifically described below is merely an example, and does not prevent other configurations from being applied or replaced.
- the hydraulic cylinder 113 is shown as an actuator for opening and closing the mold in the present embodiment, it may be replaced with a combination of a mechanism that converts rotational motion into linear motion and an electric motor such as a servo motor or an induction motor.
- a ball screw or a rack and pinion can be used.
- the upstream and downstream are determined based on the direction in which the resin pellets P (molten resin M) and the reinforcing fibers F are conveyed.
- the resin pellets P and the reinforcing fibers F are injected into a cavity from a discharge nozzle 203 provided at the downstream end, which is introduced by a supply hopper 207 provided at the upstream end.
- the plasticizing unit 200 is supplied with a cylindrical heating cylinder 201, a discharge nozzle 203 provided at the downstream end of the heating cylinder 201, a screw 10 provided inside the heating cylinder 201, a resin pellet P and a reinforcing fiber F. Supply hopper 207. Further, the plasticizing unit 200 includes a first electric motor 209 that moves the screw 10 forward or backward, and a second electric motor 211 that rotates the screw 10 forward or backward. Each of these elements performs a necessary operation in accordance with an instruction from the control unit 50.
- a load cell (not shown) is interposed between the downstream end (rear end) of the screw 10 and the first electric motor 209, and the load received by the screw 10 in the axial direction can be detected.
- the plasticizing unit 200 by the electric motor controls the back pressure of the screw 10 during plasticization based on the load detected by the load cell.
- the screw 10 has a two-stage design similar to a so-called gas vent type screw. Specifically, the screw 10 includes a first stage 21 provided on the upstream side and a second stage 22 connected to the first stage 21 and provided on the downstream side, and the first stage 21 is sequentially supplied from the upstream side.
- the second stage 22 includes a supply unit 25, a compression unit 26, and a measurement unit 28 in order from the upstream side. Further, the screw 10 includes a throttle portion 35 between the first stage 21 and the second stage 22. In FIG. 1, the right side is the upstream side, and the left side is the downstream side.
- a first flight 31 is provided on the first stage 21, and a second flight 33 is provided on the second stage 22.
- the screw grooves between the flights in the supply units 23 and 25 are relatively deep, and the screw grooves between the flights of the compression units 24 and 26 are gradually reduced from the upstream side toward the downstream side.
- the screw grooves in the measuring portions 27 and 28 are set to be the shallowest.
- the first flight 31 of the first stage 21 has its flight lead (L1) set to be equal to or less than the flight lead (L2) of the second flight 33 of the second stage 22, that is, L1 ⁇ L2 It is preferable to hold.
- the flight lead (hereinafter simply referred to as “lead”) refers to the interval between adjacent flights.
- the lead L1 of the first flight 31 is preferably 0.4 to 1.0 times, more preferably 0.5 to 0.9 times the lead L2.
- the flight width of the second flight 33 is preferably 0.01 to 0.3 times the lead L2 (0.01 ⁇ L2 to 0.3 ⁇ L2). If the flight width is less than 0.01 times the lead L2, the strength of the second flight 33 is insufficient, and if the flight width exceeds 0.3 times the lead L2, the screw groove width becomes smaller and the fiber is at the top of the flight. This is because it becomes difficult to fall into the groove due to being caught in. Further, in addition to the above-described preferable form in which L1 ⁇ L2 is satisfied, the second flight 33 of the second stage 22, in particular, a part or all of the supply unit 25 may be a plurality of flights instead of a single flight.
- the molten resin M discharged from the first stage 21 is divided and distributed into screw grooves partitioned by a plurality of flights, so that the fiber bundle and the molten resin M are respectively in each screw groove. Since they are contacted and mixed, it is effective for impregnating the molten resin M into the fiber bundle.
- the throttle part 35 provided between the first stage 21 and the second stage 22 has an outer diameter D 2 of the measuring part 27 of the first stage 21 as shown in FIG. It is set larger than the shaft diameter D 1 and the outer diameter D 3 of the supply unit 25 of the second stage 22.
- the diameter of the shaft portion of the screw 10 is larger in the radial direction than the measuring portion 27 in the throttle portion 35, and the shaft portion of the supply portion 25 connected to the throttle portion 35 is The diameter is shrinking.
- the screw 10 is set so that the outer diameter D 3 of the supply unit 25 of the second stage 22 is smaller than the outer diameter D 1 of the measuring unit 27.
- the pressure can be reduced. That is, the inside of the heating cylinder 201 and the periphery of the throttle unit 35 forms the throttle region of the present invention, and the inside of the heating cylinder 201 and the periphery of the supply unit 25 in the vicinity of the throttle unit 35 It constitutes the reduced pressure region of the invention. Thereby, while producing a spring back phenomenon about a fiber bundle, a ballast effect can be produced about molten resin. This will be described in detail later. In FIG. 3, the description of the first flight 31 and the second flight 33 is omitted.
- the general operation of the plasticizing unit 200 is as follows. Please refer to FIG.
- pellets (resin pellets P) made of thermoplastic resin and reinforcing fibers F supplied from the supply hopper 207 are discharged to the discharge nozzle 203 at the downstream end of the heating cylinder 201. It is conveyed toward.
- the resin pellets P become the molten resin M.
- a predetermined amount is injected into a cavity formed between the fixed mold 103 and the movable mold 109 of the mold clamping unit 100.
- the basic operation of the screw 10 is that the injection is performed by moving forward after the screw 10 is moved backward while receiving the back pressure as the resin pellet P melts.
- other configurations such as providing a heater for melting the resin pellets P on the outside of the heating cylinder 201 are not prevented from being applied or replaced.
- the injection molding machine 1 including the above elements performs injection molding according to the following procedure.
- the injection molding is performed by closing the movable mold 109 and the fixed mold 103 and clamping at a high pressure, and plasticizing the resin pellet P by heating and melting in the heating cylinder 201.
- a plasticizing step an injection step of injecting and filling the plasticized molten resin M into a cavity formed by the movable mold 109 and the fixed mold 103, and until the molten resin M filled in the cavity is solidified.
- a holding process to cool, a mold opening process to open the mold, and a take-out process to take out the molded product that has been cooled and solidified in the cavity are carried out, and the above-mentioned processes are performed sequentially or partially in parallel. Thus, one cycle of injection molding is completed.
- the resin pellets P and the reinforcing fibers F are supplied from a supply port corresponding to the supply hopper 207 on the upstream side of the heating cylinder 201.
- the screw 10 at the beginning of plasticization is located downstream of the heating cylinder 201, and is retracted while rotating the screw 10 from the initial position (FIG. 2 (a) "Begin plasticization”).
- the resin pellet P supplied between the screw 10 and the heating cylinder 201 is gradually melted while being heated by receiving a shearing force, and is conveyed downstream.
- the rotation (direction) of the screw 10 in the plasticizing step is assumed to be normal rotation.
- the reinforcing fibers F are kneaded and dispersed in the molten resin M, and are conveyed downstream together with the molten resin M.
- the molten resin M is transported to the downstream side of the heating cylinder 201 together with the reinforcing fibers F and is accumulated downstream of the screw 10. .
- the screw 10 is moved backward by a balance between the resin pressure of the molten resin M accumulated downstream of the screw 10 and the back pressure that suppresses the screw 10 from moving backward. Thereafter, when the amount of molten resin M necessary for one shot is weighed and accumulated, the rotation and retreat of the screw 10 are stopped (FIG. 2 (b) “plasticization completed”).
- FIG. 2 shows the states of resin (resin pellet P, molten resin M) and reinforcing fiber F in four stages of “unmelted resin”, “resin melt”, “fiber dispersion”, and “fiber dispersion complete”. ing.
- fiber dispersion completion downstream of the screw 10 indicates a state in which the reinforcing fibers F are dispersed in the molten resin M and used for injection, and “fiber dispersion” It shows that the supplied reinforcing fiber F is dispersed in the molten resin M with the rotation of the screw 10.
- reinforcing fiber F may be unevenly distributed in the “fiber dispersion complete” region.
- FIG. 3B shows a model of the springback phenomenon in the radial direction, in reality, the springback phenomenon occurs similarly in the circumferential direction.
- the molten resin M When attention is paid to the molten resin M passing through the throttle portion 35, the molten resin M has viscoelasticity, so that a ballast effect is generated.
- This state is shown in FIG. 3C by modeling the molten resin M as an arrow.
- the molten resin M that has been transported on the upstream side of the throttle unit 35 receives a compressive force when passing through the throttle unit (squeezing region) 35 and therefore contracts from the upstream side.
- interval of the arrow represents shrinkage
- the reinforcing fiber F floats in the molten resin M and adheres to the molten resin M, the fiber bundles included in the molten resin M are changed as the molten resin M expands due to the ballast effect.
- Each reinforcing fiber F constituting the fiber bundle is pulled by the expansion of the adhering molten resin M, and a gap between the fiber bundles is widened. Therefore, the fiber bundle is easily opened, and the molten resin M is formed in the gap. While entering and preventing the gap between the spread fibers from being bound again, the shearing force due to the molten resin M easily propagates to the reinforcing fibers F existing inside the fiber bundle.
- the mixture of the reinforcing fiber F and the molten resin M that is easily opened by the synergistic effect of the springback phenomenon and the ballast effect is supplied to the supply unit 25, the compression unit 26, and the metering unit of the second stage 22.
- the fiber bundle When passing through the portion 28, the fiber bundle is subjected to shearing forces in various directions while being sufficiently swung or displaced in the screw groove by the rotation of the screw, so that the opening of the fiber bundle is promoted and the opening of the fiber is promoted. It is possible to prevent molding defects due to defects or defective filling during injection and measurement defects during plasticization.
- the effect of the mixture passing through the constricted portion 35 becomes significant when a shearing force is applied in two orthogonal directions. That is, as shown in FIG. 3A, the shearing force applied to the reinforcing fiber bundle when passing through the narrowed portion 35 is the shearing force Q in the direction of the rotation axis C of the screw 10 due to the flow of the molten resin M. H and shear forces Q V in a direction orthogonal to the rotation axis C are applied in a direction independent from each other.
- the flow path of the mixture in the throttle part 35 is the outer diameter surface of the screw 10 on the inner diameter side, and the inner diameter surface of the heating cylinder 201 on the outer diameter side. Therefore, when the screw 10 is retracted during plasticization measurement, the inner diameter surface of the heating cylinder 201 moves relatively forward when the position of the screw 10 is used as a reference.
- the mixture located in the vicinity of the inner diameter surface of the heating cylinder 201 in the throttle portion 35 receives not only the pressure at the tip of the first stage 21 but also the drag force due to the relative movement of the inner diameter surface of the heating cylinder 201. become. Dragging the mixture in the squeezing part 35 to the supply part 25 by this drag force effectively works to prevent the clogging of the mixture at the squeezing part 35.
- the degree of the effect of the described spring back phenomenon and ease of opening based on Barus effect is governed by the ratio of the shaft diameter D 3 of the supply unit 25 to the outer diameter D 2 of the diaphragm portion 35, to the outer diameter D 2 the larger the ratio of the shaft diameter D 3 (shaft diameter D 3 / outer diameter D 2) is small, the degree of the compression to decompression increases, spring back phenomenon and Barus effect tends to be remarkable.
- the shaft diameter D 3 / outer diameter D 2 is preferably 0.95 or less, more preferably 0.9 or less, and further preferably 0.8 or less.
- the shaft diameter D 3 / outer diameter D 2 is preferably 0.5 or more, and more preferably 0.6 or more. preferable.
- the shaft diameter D 3 of the supply unit 25 it is preferable that the shaft diameter D 1 less the metering section 27 is the end portion of the first stage. This reduces the pressure applied to the reinforcing fibers F and the molten resin M at the end of the first stage, in order to facilitate the opening of the reinforcing fibers F, the shaft diameter D 3 of the supply portion 25 of the first stage not more than the shaft diameter D 1 of the metering section 27 is the end portion, is because effective to enlarge the groove volume of the supply unit 25 from the groove volume of the metering unit 27.
- the compression applied to the reinforcing fiber F and the molten resin M is sufficiently released at the end of the first stage, and the opening is performed in an environment where the reinforcing fiber F can freely rotate and replace its position ignoring the pressure. to facilitate, it is further preferred shaft diameter D 3 smaller than the shaft diameter D 1.
- the screw 10 according to the present embodiment is obtained by kneading the mixture of the reinforcing fiber F and the molten resin M, which is easily opened by providing the throttle portion 35, in the second stage 22. Since the opening of the fiber bundle can be promoted, it is possible to prevent molding failure due to poor fiber opening, poor filling during injection, and poor metering during plasticization.
- the present invention has been described based on the embodiments.
- the configuration described in the above embodiments may be selected or changed to other configurations as appropriate without departing from the gist of the present invention. is there.
- the throttle portion 35 is provided at the boundary of the two-stage screw 10 including the first stage 21 and the second stage 22, but the reinforcing fiber F and the molten resin M are in a mixed state.
- the present invention is not limited to this as long as the springback phenomenon and the ballast effect are obtained.
- the two-stage screw 10 can be provided within the range of the first stage 21 or can be provided within the range of the second stage 22.
- the diaphragm 35 is provided in the range of the second stage 22, such as two or three or more places. It can also be provided.
- the screw to which the throttle unit 35 is applied is not limited to the two-stage type, but may be a one-stage type that includes one supply unit and one compression unit.
- the throttle portion 35 is ring-shaped and has an all-around dam shape
- the present invention is not limited to this.
- the main flight 36 and the sub flight 37 (37 ⁇ / b> A, 37 ⁇ / b> B) having an outer diameter smaller than that of the main flight 36 are set in the screw 10. )
- the sub flight 37 can function as the throttle portion 35.
- 4A shows an example in which the sub flight 37 has one stage
- FIG. 4B shows an example in which the sub flight 37 has two stages at intervals.
- the main flight 36 corresponds to the first flight 31 or the second flight 33.
- the sub flight 37 has a barrier flight shape in which the lead angle is set larger than that of the main flight 36 and both ends thereof are closed with respect to the main flight 36, and the effects of the present invention can be obtained.
- the throttle portion composed of the secondary flights 37 (37A, 37B) has a screw structure, as shown in FIG. 4C, the secondary flight 37, which is the throttle portion when the screw rotates, is indicated by an arrow in the drawing. Even if the reinforcing fiber F is easily clogged at the squeezed part due to the high content of the reinforcing fiber F, the reinforcing fiber is not clogged by the conveying force that can be formed by the screw structure. A mixture of F and molten resin M can be passed through the throttle portion.
- the lower limit of the size of the gap between the outer diameter of the secondary flight 37 and the cylinder inner diameter is 0.1 mm, and the upper limit is 8 mm or 60% of the groove depth. It is preferable that either one of these be smaller. If it is smaller than 0.1 mm, the reinforcing fiber F closes the gap, and if it is larger than 8 mm or 60% of the groove depth, whichever is smaller, clogging occurs due to insufficient resin transport capacity downstream of the flight leads. This is because the prevention effect cannot be expected.
- the range of the size of the gap can also be applied to a ring shape and an all-around dam shape. This can more effectively prevent clogging in the ring-shaped throttle part.
- the outer diameter of the throttle portion provided on the downstream side of the throttle portions provided at the plurality of locations is further set to the outer diameter of the throttle portion provided on the upstream side.
- it may be relatively large.
- a large gap between the upstream cylinder inner diameter and the outer diameter of the throttle part breaks up the remaining fiber bundle, and the separated fibers are strengthened with advanced fiber opening in the small throttle part of the downstream gap. It is effective to apply uniform shear to the fiber bundle and uniformly disperse it in the molten resin.
- the outer diameters of the subflights 37A and 37B are constant, but the outer diameter of the subflight 37B on the downstream side is larger than that of the subflight 37A on the upstream side (right side in the figure). Is.
- the outer diameter of the sub flight 37A increases from the upstream end toward the downstream end, and the outer diameter of the sub flight 37B increases from the upstream end toward the downstream end. It is also possible to combine the first form and the second form.
- the expansion element of the mixture by decompressing the mixture discharged from the throttle part was shown as the springback phenomenon of the reinforcing fiber F and the ballast effect of the molten resin M
- the volatile gas component is contained in a large amount.
- the volatile component dissolved in the molten resin M due to reduced pressure can be gasified and become apparent, and can also be used as an expansion element of the molten resin M.
- the throttle part 35 is applied to an injection molding machine that supplies resin pellets P and reinforcing fibers F together on the upstream side in the longitudinal direction of the screw. It is not limited to.
- the present invention can be applied to an injection molding machine that supplies resin pellets P on the upstream side and supplies reinforcing fibers F on the downstream side.
- the resin pellet P is supplied to the supply part or compression part of the first stage 21 and the reinforcing fiber F is supplied to the supply part of the second stage 22 using a two-stage screw. If the narrowed portion 35 is provided in the range of the second stage 22 where the reinforcing fiber F and the molten resin M are in a mixed state, the spring back phenomenon and the ballast effect can be obtained.
- the resin and reinforcing fiber applied to the present invention are not particularly limited, and are known resins such as general-purpose resins such as polypropylene and polyethylene, engineering plastics such as polyamide and polycarbonate, and glass fibers and carbon fibers. Widely includes known materials such as known reinforcing fibers such as bamboo fiber and hemp fiber. In order to obtain the effects of the present invention remarkably, it is preferable to target a fiber reinforced resin having a high content of reinforcing fibers of 10% or more.
- the content of the reinforcing fiber applied to the present invention is preferably 10 to 70%, more preferably 15 to 50%.
- the reinforcing fiber and the resin raw material to be supplied are mixed and supplied separately from the reinforcing fiber and the raw material resin in order to obtain the effects of the present invention remarkably, but the reinforcing fiber is impregnated with the resin. There is no problem even if an integrated composite material is used.
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Abstract
Description
これに対して、特許文献1は、個別に用意された樹脂原料と強化繊維を、上流側のスクリュ基部に対応する位置で一緒に供給して可塑化溶融する射出成形のスクリュにおいて、供給部、圧縮部、計量部をそれぞれ1カ所有し、さらに先端にミキシングを備えたスクリュで、溶融樹脂と強化繊維の混練、分散を図っている。
また、特許文献2は、スクリュの計量部若しくはそれよりも下流側の位置に軸径を他の部分より大にして、溶融樹脂と強化繊維の混合物の通過断面積を小さくした原料圧縮部を設けることを提案している。この原料圧縮部において、上流側より送られてきた当該混合物を急激に圧縮することによりせん断力を負荷して、溶融樹脂内での強化繊維の混合、分散の促進を図ろうとしている。
ところが、特許文献1において、スクリュの圧縮部における樹脂圧縮圧力により、束をなしている繊維が潰れて固く引き締まってしまう。したがって、スクリュの回転によるせん断力および先端ミキシングによる位置置換などを加えても、繊維束が開繊するのは難しく、最終的に得られる成形品中に繊維束が混入することにより、成形品の品質不良につながる。また、混合物中に開繊不足の繊維束が残っていると、混合物を金型のキャビティに向けて射出する際に、口径の小さい流路であるノズルの射出口の一部を繊維束が塞いでしまい流動抵抗となってしまう。この場合、キャビティに充填するのに過大な高圧が必要となるとともに、混合物の充填時の流動速度も低下してしまうので、混合物が十分にキャビティに充填できず成形品形状の一部が欠損した充填不足の成形不良につながる。
また、特許文献2においても同様であり、通過断面積の小さい原料圧縮部を通過する過程で、繊維が潰れて固く引き締まってしまい、原料圧縮部においてせん断力を受けても、開繊が十分に進まない。したがって、特許文献2においても、繊維束が成形品に混入して、成形品の品質不良につながる。また、特に特許文献2においては、スクリュの下流側に逆流防止弁が備えられているが、一般に逆流防止弁は内部の溶融樹脂流路が狭いため、混合物中に開繊不足の繊維束が残っていると、流路の一部を繊維束が塞いで目詰まりが発生してしまうおそれがある。この場合、可塑化能力の低下、あるいは可塑化不能(計量不能)な状態を発生してしまうおそれがある。さらには、射出時の逆流防止弁の流路閉鎖部に繊維束が挟まり流路閉鎖不良を発生させて、混合物のスクリュ側への逆流を防止できない場合がある。この場合、所定量に可塑化計量した溶融樹脂が減量してしまうため、成形品形状の一部が欠損した充填不足の成形不良が発生する。
そこで本発明は、繊維が潰れて固く引き締まってしまったとしても、その開繊を進めることのできる射出成形方法を提供することを目的とする。
また本発明は、そのような射出成形方法に好適な射出成形機のスクリュ及び射出成形機を提供することを目的とする。
すなわち本発明は、回転軸を中心にして回転が可能で、かつ、回転軸に沿って前進及び後退が可能なスクリュを備えるシリンダに、固体状の樹脂原料と強化繊維を供給し、スクリュを正転させることにより、強化繊維と溶融樹脂の混合物を生成する可塑化工程と、強化繊維と溶融樹脂の混合物を、金型のキャビティに向けて射出する射出工程と、を備え、可塑化工程において、強化繊維と溶融樹脂の混合物に対し、スクリュの回転軸方向の少なくとも一部に設けられる絞り領域において、当該絞り領域よりも上流側に比べて強い圧縮力を与え、次いで、絞り領域を通過した下流側における減圧領域において、減圧させた後、混合物をスクリュの回転により混練することを特徴とする。
このスクリュは、外径D2に対する軸径D3の比(軸径D3/外径D2)が、0.5~0.95であることが好ましい。
またこのスクリュは、絞り部よりも上流側のスクリュの軸径D1よりも、減圧部における軸径D3を小さくすることができる。
このスクリュにおいて、絞り部は、スクリュの軸径よりも外径が全周に亘って拡大されたリング状の形態をなすことが好ましい。また、この絞り部は、主フライトと、主フライトよりも外径が小さく設定されている副フライトと、を備え、副フライトは、主フライトよりリード角が大きく設定されて、その両端が主フライトに対して閉塞されていることが好ましい。
また、本発明の射出成形機は、吐出ノズルが設けられたシリンダと、シリンダの内部に、回転軸を中心にして回転が可能で、かつ、回転軸に沿って前進及び後退が可能に設けられたスクリュと、を備え、繊維強化樹脂を射出成形する射出成形機であって、スクリュは、固体状の樹脂原料を可塑化溶融して溶融樹脂と強化繊維の混合物を生成する溶融部と、生成された混合物が通過する少なくとも一部の領域に設けられ、当該一部の領域よりも上流側のスクリュの軸径よりも外径が拡大された絞り部と、下流側において絞り部に連なり、絞り部の外径よりも軸径が縮小された減圧部と、絞り部の下流端に連なり、絞り部から吐出した混合物をスクリュの回転により混練する混練部と、を備えることを特徴とする。
本実施形態に係る射出成形機1は、図1に示すように、型締ユニット100と、可塑化ユニット200と、これらのユニットの動作を制御する制御部50と、を備えている。
以下、型締ユニット100の構成と動作、可塑化ユニット200の構成と動作の概略について説明し、次いで、射出成形機1による射出成形の手順について説明する。
型締ユニット100は、ベースフレーム101上に固設されるとともに固定金型103が取り付けられた固定ダイプレート105と、油圧シリンダ113を作動させることによってレールや摺動板などの摺動部材107上を図中左右方向に移動するとともに可動金型109が取り付けられた可動ダイプレート111と、固定ダイプレート105と可動ダイプレート111とを連結する複数のタイバー115とを備えている。固定ダイプレート105には、各タイバー115と同軸に型締め用の油圧シリンダ117が設けられており、各タイバー115の一端は油圧シリンダ117のラム119に接続されている。
これらの各要素は制御部50の指示にしたがって必要な動作を行なう。
型締ユニット100の概略の動作は以下の通りである。
まず、型開閉用の油圧シリンダ113の作動により可動ダイプレート111を図中の二点鎖線の位置まで移動させて可動金型109を固定金型103に当接させる。次いで、各タイバー115の雄ねじ部121と可動ダイプレート111に設けられた半割りのナット123を係合させて、可動ダイプレート111をタイバー115に固定する。そして、油圧シリンダ117内の可動ダイプレート111側の油室の作動油の圧力を高めて、固定金型103と可動金型109とを締め付ける。このようにして型締めを行った後に、可塑化ユニット200から金型のキャビティ内に溶融樹脂Mを射出して成形品を成形する。
なお、本実施形態及び本発明において、上流及び下流は、樹脂ペレットP(溶融樹脂M)及び強化繊維Fが、搬送される向きを基準にして定められるものである。樹脂ペレットP及び強化繊維Fは上流端に設けられる供給ホッパ207にて投入される、下流端に設けられる吐出ノズル203からりキャビティへ射出される。
可塑化ユニット200は、筒型の加熱シリンダ201と、加熱シリンダ201の下流端に設けた吐出ノズル203と、加熱シリンダ201の内部に設けられたスクリュ10と、樹脂ペレットPと強化繊維Fが供給される供給ホッパ207と、を備えている。また、可塑化ユニット200は、スクリュ10を前進又は後退させる第1電動機209と、スクリュ10を正転又は逆転をさせる第2電動機211と、を備えている。これらの各要素は制御部50の指示にしたがって必要な動作を行なう。
スクリュ10の下流側の端部(後端)と第1電動機209の間には、図示を省略するロードセルが介在しており、スクリュ10が軸方向に受ける荷重を検知することができる。電動機による可塑化ユニット200は、ロードセルで検知した荷重に基づいて、可塑化におけるスクリュ10の背圧を制御する。
第1ステージ21及び第2ステージ22ともに、相対的に、供給部23,25におけるフライト間のスクリュ溝が深く、圧縮部24,26のフライト間のスクリュ溝が上流側から下流側に向けて漸減していうように設定され、計量部27,28におけるスクリュ溝が最も浅く設定されている。
この機能を得るために、第1ステージ21の第1フライト31は、そのフライトリード(L1)が第2ステージ22の第2フライト33のフライトリード(L2)以下とすること、つまりL1≦L2が成り立つことが好ましい。なお、フライトリード(以下、単にリード)とは、前後に隣接するフライトの間隔をいう。一つの指標として、第1フライト31のリードL1は、リードL2の0.4~1.0倍とするのが好ましく、0.5~0.9倍とすることがより好ましい。
また、上述したL1≦L2が成り立つ好ましい形態の他、第2ステージ22の特に供給部25の一部または全部の第2フライト33は、1条フライトではなく、複数条数のフライトでもよい。この場合、第1ステージ21から吐出された溶融樹脂Mが、複数条数のフライトにより区画されたスクリュ溝にそれぞれ分割して分配されるため、各スクリュ溝内で繊維束と溶融樹脂Mがそれぞれ接触、混合されるので、繊維束への溶融樹脂Mの含浸に有効である。
可塑化ユニット200の概略の動作は以下の通りである。なお、図1を参照願いたい。
加熱シリンダ201の内部に設けられたスクリュ10が回転すると、供給ホッパ207から供給された熱可塑性樹脂からなるペレット(樹脂ペレットP)と強化繊維Fは、加熱シリンダ201の下流端の吐出ノズル203に向けて搬送される。この過程で、樹脂ペレットPは溶融樹脂Mとなる。溶融樹脂Mは強化繊維Fと混合された後に、型締ユニット100の固定金型103と可動金型109の間に形成されるキャビティへ所定量だけ射出される。なお、樹脂ペレットPの溶融に伴いスクリュ10が背圧を受けながら後退した後に、前進することで射出を行なうというスクリュ10の基本動作を伴うことは言うまでもない。また、加熱シリンダ201の外側には、樹脂ペレットPの溶融のためにヒータを設けるなど、他の構成を適用し、あるいは置換することを妨げない。
以上の要素を備える射出成形機1は、以下の手順で射出成形を行なう。
射出成形は、よく知られているように、可動金型109と固定金型103を閉じて高圧で型締めする型締工程と、樹脂ペレットPを加熱シリンダ201内で加熱、溶融して可塑化させる可塑化工程と、可塑化された溶融樹脂Mを、可動金型109と固定金型103により形成されるキャビティに射出、充填する射出工程と、キャビティに充填された溶融樹脂Mが固化するまで冷却する保持工程と、金型を開放する型開き工程と、キャビティ内で冷却固化された成形品を取り出す取り出し工程と、を備え、上述した各工程をシーケンシャルに、あるいは一部を並行させて実施して1サイクルの射出成形が完了する。
[可塑化工程]
可塑化工程では、樹脂ペレットP及び強化繊維Fを加熱シリンダ201の上流側の供給ホッパ207に対応する供給口から供給する。可塑化開始当初のスクリュ10は、加熱シリンダ201の下流に位置しており、その初期位置からスクリュ10を回転させながら後退させる(図2(a)「可塑化開始」)。スクリュ10を回転させることで、スクリュ10と加熱シリンダ201の間に供給された樹脂ペレットPは、せん断力を受けて加熱されながら徐々に溶融して、下流に向けて搬送される。なお、本発明では可塑化工程におけるスクリュ10の回転(向き)を正転とする。スクリュ10の回転に伴い、強化繊維Fは溶融樹脂Mに混錬、分散して溶融樹脂Mとともに下流に搬送される。樹脂ペレットP、強化繊維Fの供給を継続するとともに、スクリュ10を回転し続けると、溶融樹脂Mが強化繊維Fとともに加熱シリンダ201の下流側に搬送され、かつ、スクリュ10よりも下流側に溜まる。スクリュ10の下流に溜まった溶融樹脂Mの樹脂圧力とスクリュ10の後退を抑制する背圧とのバランスによってスクリュ10を後退させる。この後、1ショットに必要な量の溶融樹脂Mが計量され溜まったところで、スクリュ10の回転及び後退を停止する(図2(b)「可塑化完了」)。
この可塑化工程で、溶融樹脂Mと強化繊維Fの混合物(以下、単に混合物ということがある)が絞り部35を通過する過程で、前述したスプリングバック現象とバラス効果が生じる。以下、図3(b),(c)を参照して説明する。
第1ステージ21において、可塑化溶融された溶融樹脂M中で強化繊維Fが混練され、繊維束をある程度は分散されるが、第1ステージ21に連なる絞り部35に溶融樹脂Mとともに強化繊維Fが流入し、絞り部35を通過すると、第2ステージ22の供給部25に流入する。つまり、混合物は、絞り領域で圧縮された後に減圧領域に達する。そして、この減圧領域は、混合物に対して、膨張環境になる。
絞り部35よりも上流側では、繊維束Bはこれを構成する強化繊維Fが屈曲するなどして相互に所定の隙間を有しているが、絞り部(絞り領域)35に達すると、圧縮力を受けることにより、それぞれの強化繊維Fが潰れて繊維束Bは引き締まる。しかし、絞り部35を通過して供給部25の周囲の減圧領域に達すると、それぞれの強化繊維Fにスプリングバック現象が生じることで、繊維束Bを構成する束ねられたそれぞれの強化繊維Fの隙間が広がり、繊維束を開繊しやすい状態を作り出すことができる。なお、図3(b)は径方向におけるスプリングバック現象をモデル化して示しているが、現実には、周方向においても同様にスプリングバック現象が生じることになる。
また、強化繊維Fは溶融樹脂Mの中に浮遊しており、溶融樹脂Mに付着しているので、バラス効果による溶融樹脂Mの膨張に伴って、溶融樹脂Mの中に含まれる繊維束を構成するそれぞれの強化繊維Fが、付着している溶融樹脂Mの膨張に引っ張られて、繊維束の間の隙間が広がるので、繊維束が開繊しやすくなるとともに、この隙間の中に溶融樹脂Mが浸入して、広がった繊維間の隙間が再び結着してしまうのを防ぐとともに、溶融樹脂Mによるせん断力が繊維束の内部に存在する強化繊維Fにも伝搬しやすくなる。
つまり、図3(a)に示すように、絞り部35を通過する際に、強化繊維束に負荷されるせん断力は、溶融樹脂Mの流れによるスクリュ10の回転軸Cの方向のせん断力QHと、回転軸Cと直交する方向のせん断力QVという、互いに独立な方向のせん断力が負荷される。したがって、溶融樹脂Mの中に含まれる強化繊維F及び繊維束の方向が如何なる方向に向いていても、絞り部35を通過する際に、せん断力QHとせん断力QVのいずれかが繊維束を解くように負荷することができるので、絞り部35を通過することによる開繊の効果を顕著なものにする。
射出工程に入ると、図2(c)に示すように、スクリュ10を前進させる。そうすると、スクリュ10の先端部に備えられている図示しない逆流防止弁が閉鎖することで、スクリュ10の下流に溜まった溶融樹脂Mの圧力(樹脂圧力)が上昇し、溶融樹脂Mは吐出ノズル203からキャビティに向けて吐出される。
以後は、保持工程と、型開き工程と、取り出し工程を経て、1サイクルの射出成形が完了し、次のサイクルの型締め工程、可塑化工程が行われる。
以上説明したように、本実施形態によるスクリュ10は、絞り部35を設けることにより、開繊しやすい状態となった強化繊維Fと溶融樹脂Mの混合物を、第2ステージ22において混練することによって、繊維束の開繊を促進できるので、繊維の開繊不良や射出時の充填不良による成形不良や可塑化時の計量不良を防止できる。
例えば、以上の本実施形態では、第1ステージ21と第2ステージ22を備える2ステージ型のスクリュ10の境界に絞り部35を設けたが、強化繊維Fと溶融樹脂Mが混合状態にあって、スプリングバック現象とバラス効果が得られる限り、本発明はこれに限定されない。2ステージ型のスクリュ10について、第1ステージ21の範囲内に設けることができるし、第2ステージ22の範囲内に設けることもできる。また、例えば、第1ステージ21と第2ステージ22の境界部分に加えて、第2ステージ22の範囲内にも設けるというように、絞り部35を2か所又は3か所以上の複数か所に設けることもできる。また、絞り部35が適用されるスクリュは、2ステージ型に限るものではなく、供給部と圧縮部を一つずつ備える1ステージ型であってもよい。
また、図4(b)に示すように、絞り部を複数個所に設けられる副フライト37A,37Bによって形成した場合は、副フライト37A,37Bにおける外径を上流側から下流側に向けて滑らかにあるいは段階的に拡大させてもよい。これにはいくつかの形態が含まれている。一つ目の形態は、副フライト37A,37Bのそれぞれの外径は一定であるが、上流側(図中の右側)の副フライト37Aに比べて下流側の副フライ37Bの外径が大きいというものである。二つ目の形態は、副フライト37Aの外径が上流端から下流端に向けて大きくなり、副フライト37Bの外径が上流端から下流端に向けて大きくなるというものである。一つ目の形態と二つ目の形態を組み合せることもできる。
10 スクリュ
21 第1ステージ
22 第2ステージ
23,25 供給部
24,26 圧縮部
27,28 計量部
31 第1フライト
33 第2フライト
35 絞り部
36 主フライト
37,37A,37B 副フライト
50 制御部
100 型締ユニット
101 ベースフレーム
103 固定金型
105 固定ダイプレート
107 摺動部材
109 可動金型
111 可動ダイプレート
113 油圧シリンダ
115 タイバー
117 油圧シリンダ
119 ラム
121 雄ねじ部
123 ナット
200 可塑化ユニット
201 加熱シリンダ
203 吐出ノズル
207 供給ホッパ
209 第1電動機
211 第2電動機
C 回転軸
F 強化繊維
M 溶融樹脂
P 樹脂ペレット
Claims (9)
- 回転軸を中心にして回転が可能で、かつ、前記回転軸に沿って前進及び後退が可能なスクリュを備えるシリンダに、固体状の樹脂原料と強化繊維を供給し、前記スクリュを正転させることにより、前記強化繊維と溶融樹脂の混合物を生成する可塑化工程と、
前記混合物を、金型のキャビティに向けて射出する射出工程と、を備え、
前記可塑化工程において、
前記混合物に対し、
前記スクリュの前記回転軸方向の少なくとも一部に設けられる絞り領域において、前記絞り領域よりも上流側に比べて強い圧縮力を与え、
次いで、前記絞り領域を通過した下流側における減圧領域において、減圧させ、
減圧後に前記スクリュの前記回転により前記混合物に対し混練を加える、
ことを特徴とする射出成形方法。 - 前記可塑化工程において、
前記樹脂原料と前記強化繊維は、前記絞り領域よりも、上流側において供給され、
前記絞り領域に達するまでの間に、前記混合物が生成される、
請求項1に記載の射出成形方法。 - 前記スクリュは、
生成された前記混合物が通過する少なくとも一部の領域に設けられ、当該一部の領域よりも上流側の前記スクリュの軸径D1よりも外径D2が拡大された絞り部と、
下流側において前記絞り部に連なり、前記絞り部の外径D2よりも軸径D3が縮小された減圧部と、
前記減圧部の下流端に連なり、前記混合物を混練する混練部と、を備え、
前記絞り領域は、前記シリンダの内部であって、前記絞り部の周囲に設けられ、
前記膨張領域は、前記シリンダの内部であって、前記減圧部の周囲に設けられ、
前記混練部を、前記シリンダの内部であって、前記膨張領域の周囲に設ける、
請求項1又は請求項2に記載の射出成形方法。 - 前記外径D2に対する前記軸径D3の比(軸径D3/外径D2)が、0.5~0.95である、
請求項3に記載の射出成形方法。 - 前記絞り部よりも上流側の前記スクリュの軸径D1よりも、前記減圧部における前記軸径D3が小さい、
請求項3又は請求項4に記載の射出成形方法。 - 溶融樹脂と強化繊維の混合物を射出成形して繊維強化樹脂を得るのに用いられる射出成形機のスクリュであって、
固体状の樹脂原料を可塑化溶融して前記溶融樹脂と前記強化繊維の混合物を生成する溶融部と、
生成された前記混合物が通過する少なくとも一部の領域に設けられ、当該一部の領域よりも上流側の前記スクリュの軸径よりも外径が拡大された絞り部と、
下流側において前記絞り部に連なり、前記絞り部の外径よりも前記軸径が縮小された減圧部と、
前記減圧部の下流端に連なり、前記混合物を混練する混練部と、
を備えることを特徴とするスクリュ。 - 前記絞り部は、
前記スクリュの軸径よりも外径が全周に亘って拡大されたリング状の形態をなす、請求項6に記載のスクリュ。 - 前記絞り部は、
主フライトと、前記主フライトよりも外径が小さく設定されている副フライトと、を備え、
前記副フライトは、前記主フライトよりリード角が大きく設定されて、その両端が前記主フライトに対して閉塞されている、
請求項6又は請求項7に記載のスクリュ。 - 吐出ノズルが設けられたシリンダと、
前記シリンダの内部に、回転軸を中心にして回転が可能で、かつ、前記回転軸に沿って前進及び後退が可能に設けられたスクリュと、を備え、繊維強化樹脂を射出成形する射出成形機であって、
前記スクリュは、
固体状の樹脂原料を可塑化溶融して溶融樹脂と強化繊維の混合物を生成する溶融部と、
生成された前記混合物が通過する少なくとも一部の領域に設けられ、当該一部の領域よりも上流側の前記スクリュの軸径よりも外径が拡大された絞り部と、
下流側において前記絞り部に連なり、前記絞り部の外径よりも軸径が縮小された減圧部と、
前記減圧部の下流端に連なり、前記混合物を混練する混練部と、を備える、
ことを特徴とする射出成形機。
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US15/543,783 US20180022003A1 (en) | 2015-01-16 | 2015-01-16 | Injection molding method, screw for injection molding machine, and injection molding machine |
PCT/JP2015/000167 WO2016113777A1 (ja) | 2015-01-16 | 2015-01-16 | 射出成形方法、射出成形機のスクリュ及び射出成形機 |
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DE102020111510A1 (de) | 2020-04-28 | 2021-10-28 | Kraussmaffei Technologies Gmbh | Plastifiziereinheit |
CN114083793B (zh) * | 2021-10-18 | 2024-05-17 | 深圳市创想三维科技股份有限公司 | 挤出机构及3d打印机 |
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AU3582278A (en) * | 1977-05-17 | 1979-11-08 | Continental Group | Injection molding screw |
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