JP2017035821A - Injection molding machine and injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be able to sufficiently prevent deterioration in the mechanical strength of a molded article and to be able to sufficiently improve the durability.SOLUTION: An injection molding machine includes: an injection device; a mold device; a molding material push-in device including a push-in member and a push-in drive part; and a control part which, when the molding material is divided and right before joined at a confluent part in a cavity space Cv, pushes the molding material in a molding material reservoir part into the cavity space Cv to make the molding material in the cavity space Cv flow back into a cylinder member. Since the molding material in the molding material reservoir part is pushed into the cavity space Cv to be flown back into the cylinder member right before the molding material joins at the confluent part, the molding material can be sufficiently circulated in the confluent part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an injection molding machine and an injection molding method.

  Conventionally, in an injection molding machine, a resin as a molding material is melted in a heating cylinder, filled in a cavity space in a mold apparatus, cooled in the cavity space, and solidified to form a molded product. It has come to be.

  The injection molding machine has a mold apparatus and an injection apparatus, and the mold apparatus is a fixed mold, a movable mold disposed so as to be movable back and forth with respect to the fixed mold, and advancing and retracting the movable mold. A mold clamping device that opens and closes the mold, and the injection device includes a heating cylinder for heating and melting the resin, a screw disposed in the heating cylinder so as to be rotatable and movable back and forth, and the screw A drive device or the like is provided for rotating and reciprocating.

  In the injection device, when the drive device is driven to rotate the screw and measure the resin, the screw is retracted while accumulating resin melted forward (hereinafter referred to as “molten resin”). In the mold clamping device, a cavity is formed between the fixed mold and the movable mold by advancing the movable mold and bringing it into contact with the fixed mold. When the drive device is driven to advance the screw, the molten resin is injected from the injection nozzle and filled into the cavity space.

  By the way, in the injection molding machine, depending on the shape of the molded product, the molten resin may flow in the cavity space. In this case, when the divided molten resin joins, a weld is formed. At the boundary portion where the molten resin joins, that is, at the weld, the molten resin is almost solidified to form a weld line in the molded product. As a result, the bending strength is reduced or cracks are generated. As a result, the mechanical strength is lowered and the durability of the molded product is lowered.

  Therefore, an injection molding machine is provided in which a resin reservoir is formed at a predetermined location in the cavity space. In the injection molding machine, as the molten resin enters the resin pool, a pressure difference is generated in the weld portion, and the molten resin flows through the weld portion. Thereby, it can prevent that the mechanical strength of a molded article becomes low and can improve durability (for example, refer patent document 1).

Japanese Patent No. 2945146

  However, in the conventional injection molding machine, even if the molten resin enters the resin reservoir, a sufficient pressure difference does not occur in the weld portion, and the molten resin does not flow sufficiently in the weld portion. Therefore, the mechanical strength of the molded product cannot be prevented from being lowered, and the durability cannot be sufficiently improved.

  In particular, when molding a small and thin molded product, the skin layer is formed in the majority of the cavity space, and the core layer is hardly formed. Therefore, there is no pressure difference in the weld, and the molten resin is welded. The part does not flow. As a result, the mechanical strength of the molded product is lowered and the durability is lowered.

  The present invention solves the problems of the conventional injection molding machine, can sufficiently prevent the mechanical strength of the molded product from being lowered, and can sufficiently improve the durability. And it aims at providing the injection molding method.

  Therefore, in the injection molding machine of the present invention, a cylinder member, an injection member that is rotatably and reciprocally disposed in the cylinder member, and has a head portion at the tip, front and rear of the head portion A communication mechanism that selectively communicates with the injection device, and an injection device that includes a drive device for rotating and advancing and retracting the injection member; a first mold; A mold apparatus for forming a cavity space between the first and second molds when the second mold is brought into contact with the first mold. A molding material reservoir formed in communication with the cavity space, and a pushing member disposed so as to be able to advance and retreat with the tip facing, and a pushing drive unit for moving the pushing member forward and backward. A molding material pushing device and an injection member in the cylinder member The molten molding material is injected and injected into the cavity space, and the molding material is diverted in the cavity space, and the pressing member is advanced immediately before the molding material is joined at the joining portion. The molding material in the reservoir is pushed into the cavity space, the injection member is retracted in the cylinder member, the molding material in the cavity space is caused to flow back into the cylinder member, and then the injection member is advanced in the cylinder member. And a controller for increasing the pressure of the molding material in the cavity space.

  According to the present invention, in an injection molding machine, a cylinder member, an injection member that is rotatably and reciprocally disposed in the cylinder member, and has a head portion at the tip, front and rear of the head portion A communication mechanism that selectively communicates with the injection device, and an injection device that includes a drive device for rotating and advancing and retracting the injection member; a first mold; A mold apparatus for forming a cavity space between the first and second molds when the second mold is brought into contact with the first mold. A molding material reservoir formed in communication with the cavity space, and a pushing member disposed so as to be able to advance and retreat with the tip facing, and a pushing drive unit for moving the pushing member forward and backward. The molding material pushing device and the injection member are advanced in the cylinder member. The molten molding material is injected, filled into the cavity space, and immediately before the molding material is diverted into the cavity space and joined at the joining portion, the pushing member is advanced to collect the molding material. The molding material in the section is pushed into the cavity space, the injection member is retracted in the cylinder member, the molding material in the cavity space is caused to flow back into the cylinder member, and then the injection member is advanced in the cylinder member. And a controller for increasing the pressure of the molding material in the cavity space.

  In this case, in the cavity space, the molding material is diverted, and immediately before joining at the joining portion, the pushing member is advanced, and the molding material in the molding material reservoir is pushed into the cavity space, and in the cylinder member The injection member is retracted, the molding material in the cavity space is caused to flow back into the cylinder member, and then the injection member is advanced in the cylinder member, thereby increasing the pressure of the molding material in the cavity space. Therefore, it is possible to sufficiently flow the molding material melted at the joining portion.

  Therefore, it is possible to prevent the weld from being formed at the joining portion, and to increase the mechanical strength of the molded product. As a result, the durability of the molded product can be sufficiently improved.

It is principal part sectional drawing of the metal mold | die apparatus in the 1st Embodiment of this invention. It is a conceptual diagram of the injection molding machine in the 1st Embodiment of this invention. It is a disassembled perspective view of the screw in the 1st Embodiment of this invention. It is a control block diagram of the injection molding machine in the 1st Embodiment of this invention. It is a perspective view which shows the example of the molded article in the 1st Embodiment of this invention. It is a top view which shows the example of the molded article in the 1st Embodiment of this invention. It is AA sectional drawing of FIG. It is a longitudinal cross-sectional view of the metal mold apparatus in the 1st Embodiment of this invention. It is a top view of the fixed metal mold | die in the 1st Embodiment of this invention. It is a top view of the movable metal mold | die in the 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the protrusion apparatus and molding material pushing-in apparatus in the 1st Embodiment of this invention. It is a principal part top view of the fixed metal mold | die in the 1st Embodiment of this invention. It is a principal part top view of the movable metal mold | die in the 1st Embodiment of this invention. It is sectional drawing which shows the cavity space in the 1st Embodiment of this invention. It is a top view which shows the cavity space in the 1st Embodiment of this invention. It is a 1st figure which shows the state in which a weld is formed. It is a 2nd figure which shows the state in which a weld is formed. It is a 3rd figure which shows the state in which a weld is formed. It is a figure which shows the state which prevents that a weld is formed in the cavity space in the 1st Embodiment of this invention. It is a time chart for demonstrating operation | movement of the injection molding machine in the 1st Embodiment of this invention. It is principal part sectional drawing of the metal mold | die apparatus in the 2nd Embodiment of this invention. It is principal part sectional drawing of the metal mold | die apparatus in the 3rd Embodiment of this invention. It is principal part sectional drawing of the metal mold | die apparatus in the 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a conceptual diagram of an injection molding machine according to the first embodiment of the present invention.

  In the figure, reference numeral 10 denotes an injection molding machine, and the injection molding machine 10 includes an injection device 11, a mold device 12, and a mold clamping device 13.

  The injection device 11 includes a heating cylinder 21 as a cylinder member for heating and melting a resin as a molding material, in the present embodiment, a thermoplastic resin, and is rotatable in the heating cylinder 21 and advances and retreats. A screw 22 as an injection member provided with a screw head 61 (FIG. 3) as a head portion, which will be described later, at the tip, and disposed at the rear end of the screw 22. A driving device 23 and the like. A spiral groove m1 is formed on the surface of the screw 22 by the flight 22a formed in a spiral shape.

  The heating cylinder 21 is provided with an injection nozzle 24 for injecting molten resin at the front end, and a supply port 25 for supplying resin (pellet) into the heating cylinder 21 at the rear end. A heater 26 is attached as a heating body for heating the heating cylinder 21 and melting the resin. The drive device 23 includes a metering motor 31 as a metering drive unit for rotating the screw 22, an injection motor 32 as an injection drive unit for moving the screw 22 back and forth, and the like.

  When the metering motor 31 is driven and the screw 22 is rotated, the resin supplied into the injection device 11 through the supply port 25 is sent forward along the groove m1 of the screw 22 and gradually melted. It becomes a molten resin. Then, as the molten resin is stored in the front in the heating cylinder 21, the screw 22 is retracted.

  After the resin is metered in this way, when the injection motor 32 is driven and the screw 22 is moved forward (moved toward the mold device 12 side), the molten resin stored in front of the screw 22 is injected into the injection nozzle 24. The cavity space in the mold apparatus 12 is filled. In this embodiment, the injection speed at this time is 350 [mm / sec], and the injection pressure is 35 [MPa] to 40 [MPa].

  The mold apparatus 12 includes a fixed mold 33 as a first mold, a movable mold 34 as a second mold disposed so as to be able to contact with and separate from the fixed mold 33, and the like. Prepare. A cavity space in which the molten resin injected from the injection nozzle 24 is filled between the fixed mold 33 and the movable mold 34 by advancing the movable mold 34 and bringing it into contact with the fixed mold 33. Is formed.

  The mold clamping device 13 includes a frame 35 as a support plate, a fixed platen 36 as a first platen fixed to the frame 35, and a fixed platen 36 for attaching the fixed mold 33, and a predetermined distance from the fixed platen 36. The rear platen 37 is movably disposed with respect to the frame 35, and four tie bars 38 (two tie bars 38 are shown in the figure) installed between the fixed platen 36 and the rear platen 37. ) Between the fixed platen 36 and the rear platen 37, which is disposed movably along the tie bar 38, and is disposed on the movable platen 39 and the frame 35 as a second platen for mounting the movable mold 34. A guide 41 that guides the movable platen 39, and is disposed between the rear platen 37 and the movable platen 39. By advancing and retracting the platen 39, mold closing of the mold apparatus 12 comprises a toggle mechanism 43 such as a mold opening and closing apparatus for mold clamping and mold opening.

  On the back surface of the movable platen 39 (on the rear platen 37 side), when the mold is opened, an ejector pin (not shown) as a protruding member is protruded to drive the molded product away from the movable mold 34. The pushing motor 44 as a part, and a pushing drive part for advancing a pushing pin 251 (FIG. 1) as a pushing member, which will be described later, and as an actuator when the cavity space is filled with molten resin A push motor 45 is attached. Note that a hydraulic or pneumatic piston can be used as the drive unit for protrusion and the drive unit for pushing.

  A mold clamping motor 48 is attached to the rear surface of the rear platen 37 as a mold opening / closing drive unit for expanding and contracting the toggle mechanism 43.

  By the way, in general, in the injection molding machine 10, after weighing is performed, in order to prevent the molten resin from dripping from the tip of the injection nozzle 34, suck back is performed, and the screw 22 rotates. The pressure of the molten resin stored in front of the screw 22 is lowered by being retracted by a small amount without being moved. However, when the molten resin in the groove m1 moves forward of the screw 22 when the screw 22 is retracted, the amount of molten resin stored in front of the screw 22 varies.

  Therefore, in the present embodiment, the molten resin in the groove m1 is prevented from moving forward of the screw 22 when suckback is performed.

  FIG. 3 is an exploded perspective view of the screw according to the first embodiment of the present invention.

  In the figure, reference numeral 22 denotes a screw. The screw 22 is provided with a screw head 61 at the tip, and a helical flight 22 a is formed on the surface of the main body 62 of the screw 22 behind the screw head 61. A groove m1 is formed by 22a.

  The screw head 61 includes a head main body portion 63 having a conical shape at a front portion and a small diameter portion 64 at a rear portion, and a plurality of pairs of regulation protrusions 64a and 64b at a front end of the small diameter portion 64 (this embodiment). 2 pairs) are formed. The head bolt 65 is passed through the screw head 61, and the screw head 61 is screwed to the main body portion 62 by a screw portion 65 a formed at the rear end of the head bolt 65.

  An annular first ring 67 is fixed to the front end of the main body portion 62, and an annular second ring 68 is disposed on the outer periphery of the small diameter portion 64 so as to be adjacent to the first ring 67. The 67 and the second ring 68 constitute a backflow prevention mechanism for preventing the resin from flowing back when the resin is injected. The backflow prevention mechanism functions as a communication mechanism that selectively communicates the front and rear of the screw head 61 in the heating cylinder 21 (FIG. 2).

  The thickness of the second ring 68 is slightly smaller than the distance between the rear ends of the restricting protrusions 64 a and 64 b and the front end of the first ring 67 so that the second ring 68 does not rotate with the screw head 61. It is made smaller. This forms a clearance of about 0.1 to 0.2 mm before and after the second ring 68, but the second ring 68 moves in the axial direction when switching between injection and metering. There is nothing.

  The outer diameter of the second ring 68 is slightly smaller than the inner diameter of the heating cylinder 21, and the inner diameter is slightly larger than the outer diameter of the small diameter portion 64.

  The said 1st ring 67 has the trough part 67b as the 1st molding material flow path formed between the peak part 67a and each peak part 67a in the several places in the circumferential direction of an outer periphery.

  The second ring 68 has an opening 69 through which the small-diameter portion 64 penetrates in the center, and a second molding formed at a plurality of locations in the circumferential direction inside the outer peripheral edge so as to correspond to the valley portion 67b. It has a through hole 70 as a material flow path. Further, locking claws 71 and 72 are formed on the surface of the second ring 68 on the screw head 61 side so as to correspond to each pair of the restriction protrusions 64a and 64b, and are respectively formed between the restriction protrusions 64a and 64b. Placed.

  Therefore, the first ring 67 and the second ring 68 are made relatively swingable, and the swing range is set by the swing restricting means constituted by the locking claws 71 and 72 and the restricting protrusions 64a and 64b. Be regulated. When weighing is performed, when the screw 22 is rotated forward in the direction of arrow A, the first ring 67 is first rotated in the same direction as the screw 22, and then the second ring 68 is moved to the first ring 68. It is rotated in the same direction as the screw 22 by the frictional force generated between the ring 67 and the flow of resin generated along with the rotation of the first ring 67.

  In this case, since the first ring 67 is rotated in advance, the first ring 67 and the second ring 68 are rotated relatively, but the locking claws 71 and 72 abut against the restricting protrusion 64a. Then, it is rotated integrally. At this time, the valley portion 67b of the first ring 67 and the through hole 70 of the second ring 68 are placed at the same position in the circumferential direction and communicated with each other. The molten resin in the groove m <b> 1 62 is moved forward through the valley portion 67 b and the through hole 70 and stored in front of the screw head 61.

  When the metering is completed in this way, suckback is performed. Before the suckback is performed, the screw 22 is rotated in the direction opposite to the arrow A direction. Then, the first ring 67 is rotated in the same direction as the screw 22, and then the second ring 68 is caused by the friction force generated between the first ring 67 and the rotation of the first ring 67. The screw is rotated in the same direction as the screw 22 by the flow of the molten resin generated.

  In this case, since the first ring 67 is rotated in advance, the first ring 67 and the second ring 68 are rotated relatively, but the locking claws 71 and 72 are in contact with the restricting protrusion 64b. Then, it is rotated integrally. At this time, the valley portion 67b of the first ring 67 and the through hole 70 of the second ring 68 are placed at different positions in the circumferential direction, are not communicated, and are sealed.

  Thereafter, the screw 22 is retracted and suck back is performed, and the pressure of the resin stored in front of the screw head 61 is lowered. This prevents the resin from dripping from the tip of the injection nozzle 24. Further, at this time, even if the screw 22 is retracted, the molten resin in the main body 62 does not move forward, so that the amount of resin stored in front of the screw head 61 is prevented from fluctuating. Can do.

  Next, the control device of the injection molding machine 10 will be described.

  FIG. 4 is a control block diagram of the injection molding machine according to the first embodiment of the present invention.

  In the figure, 51 is a control unit for performing overall control of the injection molding machine 10, 52 is a memory as a storage device, and the control unit 51 is connected to the metering motor 31 via a driver dr1 and via a driver dr2. The injection mold 32 projects via a driver dr3 to the coil 53 as a heating body that heats the stationary mold 33 (FIG. 2) and the movable mold 34 by induction heating, via a driver dr4, and to the motor 44. It is connected to the push-in motor 45 via the driver dr5 and to the mold clamping motor 48 via the driver dr6.

  The control unit 51 is disposed in a control valve 55 and a heating cylinder 21 for adjusting a flow rate of a cooling chiller (not shown) as a temperature control medium for cooling the fixed mold 33 and the movable mold 34, and the heating cylinder 21, in the present embodiment, a sensor 56 as a first temperature detection unit for detecting the temperature of the molten resin in the heating cylinder 21, and a predetermined portion of the fixed mold 33 or the movable mold 34. It is provided and connected to a sensor 57 serving as a second temperature detecting unit for detecting the temperature of the mold apparatus 12 and, in the present embodiment, the temperature of the molten resin in the cavity space. The sensor 56 is disposed in the vicinity of the injection nozzle 24, and the sensor 57 is disposed in the fixed mold 33 or the movable mold 34 in the vicinity of the joining portion p3 (FIG. 14) where the molten resin in the cavity space joins. The

  By the way, in the injection molding machine 10, depending on the shape of the molded product, the molten resin may be diverted in the cavity space. In this case, when the diverted molten resin is joined and solidified at a predetermined location, a weld is formed. End up. In addition, even when a plurality of gates are provided for one cavity space, a weld is formed when the molten resin that has entered the cavity space through each gate joins and solidifies at a predetermined location. .

  Next, an example of a molded product in which a weld is formed when the molten resin is solidified at the joining portion will be described.

  FIG. 5 is a perspective view showing an example of a molded product according to the first embodiment of the present invention, FIG. 6 is a plan view showing an example of the molded product according to the first embodiment of the present invention, and FIG. It is AA sectional drawing.

  In the figure, 81 is a molded product, and the molded product 81 includes a bottom part wb having a square shape and a side part ws formed by rising from four edges of the bottom part wb, and is provided at the center of the bottom part wb. The hole 82 having a circular shape has a substantially rectangular shape at the corners of the four corners of the bottom portion wb, and a reinforcing portion 83 having a large thickness for reinforcing the molded product 81 is formed. In the present embodiment, the height of the side portion ws of the molded article 81 is set to 0.4 [mm], and the thickness of the bottom portion wb is set to 0.2 [mm].

  When forming a molded product having a hole 82 in the center, such as the molded product 81, a convex portion having a circular shape is formed at a location corresponding to the hole 82 in the core in the cavity space. In this case, after the molten resin is diverted by the convex portions in the cavity space, the molten resin is merged at a predetermined location, so that when the molten resin is solidified at the merged portion, a weld is formed.

  Next, the mold apparatus 12 for molding the molded product 81 will be described.

  FIG. 1 is a cross-sectional view of the main part of a mold apparatus according to the first embodiment of the present invention, FIG. 8 is a longitudinal cross-sectional view of the mold apparatus according to the first embodiment of the present invention, and FIG. FIG. 10 is a plan view of a movable mold according to the first embodiment of the present invention, and FIG. 11 is a projection device and molding according to the first embodiment of the present invention. FIG. 12 is a plan view of a main part of a fixed mold according to the first embodiment of the present invention, and FIG. 13 is a movable mold according to the first embodiment of the present invention. FIG. 14 is a sectional view showing the cavity space in the first embodiment of the present invention, FIG. 15 is a plan view showing the cavity space in the first embodiment of the present invention, and FIG. FIG. 17 shows a state in which a weld is formed. FIG. 18 is a third diagram showing a state in which a weld is formed, and FIG. 19 is a diagram showing a state in which a weld is prevented from being formed in the cavity space according to the first embodiment of the present invention. FIG. FIG. 15 is a view of the cavity space Cv as viewed from the fixed mold 33 side.

  In the figure, 111 is a fixed mold mounting plate as a first mounting plate, and 33 is a fixed mold. The fixed mold 33 is fixed to the fixed platen 36 (FIG. 2) via the fixed mold mounting plate 111. Attached to. Reference numeral 112 denotes a locating ring, 113 denotes a sprue bushing, and 120 denotes a sprue that is formed through the sprue bushing 113. When the injection device 11 is advanced in the injection process, the front end of the injection nozzle 24 is brought into contact with the sprue bush 113.

  Reference numeral 115 denotes a movable mold mounting plate as a second mounting plate, and 34 denotes a movable mold. The movable mold 34 is movable via a spacer block 114 and a movable mold mounting plate 115 as intermediate members. Attached to the platen 39.

  The fixed mold 33 has a fixed-side mold plate 121 and a rectangular shape (in this embodiment, a square shape), and a nesting 122 disposed in a central portion of the fixed-side mold plate 121. Holding blocks 123 to 126 are provided on the top and bottom and on the left and right to surround and hold the insert 122. The nest 122 has a main body 131 and a flange 132 formed to protrude vertically and horizontally on the surface of the main body 131 facing the movable mold 34. A rectangular annular space 134 is formed between the main body 131 and the holding blocks 123 to 126, and the coil 53 is wound around the outer peripheral surface of the main body 131 in the annular space 134.

  A flow path 136 formed by extending through the fixed side mold plate 121 in the horizontal direction above the nest 122 in the fixed side mold 121 is below the nest 122 in the fixed side mold 121. A flow path 137 formed by penetrating the fixed side mold plate 121 and extending in the horizontal direction is formed in the holding blocks 123 to 126 so as to surround the insert 122. A flow path 139 is formed at the center of the plate 121 in communication with the flow path 138, and each of the flow paths 136 to 139 is connected to a cooling chiller supply source (not shown) as a temperature control medium supply source.

  The movable mold 34 has a movable side mold plate 141 and a rectangular shape (square in the present embodiment), and a nest 142 disposed in a central portion of the movable side mold plate 141. Holding blocks 143 to 146 that surround and hold the insert 142 are provided in the vertical and horizontal directions. The nest 142 includes a main body 151 and a flange 152 formed to protrude vertically and horizontally on the surface of the main body 151 facing the fixed mold 33 of the main body 151. A rectangular annular space 154 is formed between the main body 151 and the holding blocks 143 to 146, and the coil 53 is wound around the outer peripheral surface of the main body 151 in the annular space 154.

  In place of the coil 53, a heater as a heating body for heating the fixed mold 33 and the movable mold 34 by resistance heating can be provided.

  A flow path 156 formed by passing through the movable side mold plate 141 and extending in the horizontal direction above the nest 142 in the movable side mold 141 is below the nest 142 in the movable side mold 141. A flow path 157 formed by penetrating the movable mold plate 141 and extending in the horizontal direction is formed in the holding blocks 143 to 146 so as to surround the insert 142. A flow path 159 is formed at the center of the plate 141 in communication with the flow path 158, and the flow paths 156 to 159 are connected to the cooling chiller supply source.

  When the mold device 12 is closed, clamped and opened by the toggle mechanism 43 (FIG. 2), the fixed side mold plate is used to align the position of the fixed mold 33 and the position of the movable mold 34. Guide bushes 161 as guide members having a cylindrical shape are formed at four corners of 121 through the fixed side mold plate 121, and guided members are provided at positions corresponding to the guide bush 161 in the movable side mold plate 141. The guide pin 162 is disposed, and the end of the guide pin 162 on the spacer block 114 side is fixed by sandwiching the head portion 163 between the movable mold 34 and the spacer block 114, and the guide pin 162 The end on the fixed mold 33 side is protruded from the movable mold 34 and is slidably fitted into the guide bush 161.

  By the way, in the present embodiment, in the injection molding machine 10, a plurality of molded products 81 (FIG. 5) in the present embodiment can be formed by one injection and filling. In this way, four cavity spaces Cv are formed by bringing the fixed mold 33 and the movable mold 34 into contact with each other.

  For this purpose, four cavities Csi (i = 1, 2,..., 4) are inserted into the insert 122 of the fixed mold 33, and four cores Cmi (i = 1, 2,..., 4) are inserted into the insert 142 of the movable mold 34. 4) is formed, and when the fixed mold 33 and the movable mold 34 are brought into contact with each other, the insert 122 and the insert 142 are brought into contact with each other, and a cavity space Cv is formed by each cavity Csi and the core Cmi. .

  In the present embodiment, as described above, the molded product 81 has the hole 82 having a circular shape at the center of the bottom portion wb, and the reinforcing portions 83 at the corner portions of the four corners of the bottom portion wb. A convex portion 82P having a circular shape is formed at a location corresponding to the hole 82 in the core Cmi, and a concave portion 83Q is formed at a location corresponding to each reinforcing portion 83.

  The sprue 120 and each cavity space Cv are connected via a runner 171 and four gates 172. In the present embodiment, the runner 171 has a horizontal length of 2 mm, a vertical length of 1.5 mm, and a height of 1.5 mm. The diameter of the gate 172 is set to 0.2 [mm].

  A band-shaped convex portion 173 is formed on the surface of the insert 122 of the fixed mold 33 facing the movable mold 34 so as to extend in the horizontal direction, and the surface of the insert 142 of the movable mold 34 facing the fixed mold 33. In addition, a strip-shaped recess 174 is formed in the horizontal direction so as to correspond to the projection 173, and the runner 171 is formed by forming a groove in which the fixed mold 33 side is opened in the recess 174. Then, each gate 172 is formed by forming a hole penetrating from the convex portion 173 toward each cavity space Cv. Each gate 172 is a submarine gate.

  The runner 171 includes, in the concave portion 174, vertical channels 175 and 176 extending from the portion p1 facing the tip of the sprue 120 to the left and right, vertical channels 178 and 179 extending vertically from the horizontal channel 175, and vertically from the horizontal channel 176. The longitudinal channels 181 and 182 extend. Each gate 172 is formed in the convex portion 173 so as to connect the tip of each longitudinal flow path 178, 179, 181, 182 and each cavity space Cv.

  By the way, in order to release the molded product 81 from the movable mold 34 when the mold opening is performed, a sprue lock pin 202 is disposed facing the tip of the sprue 120 and facing each cavity space Cv. In addition, an ejector pin 203 is disposed so as to be able to advance and retract so as to face a predetermined recess 83Q, for example, a recess 83Q adjacent to the gate 172. Both the sprue lock pin 202 and the ejector pin 203 are movable molds 34. The sprue lock pin 202 holds the molded product 81 and leaves it on the movable mold 34 side when the mold is opened, and the ejector pin 203 protrudes from the movable mold 34 after the mold is opened. The molded product 81 is released from the movable mold 34 and pushed down.

  For this purpose, head portions 204 and 205 are formed at the rear ends of the sprue lock pin 202 and the ejector pin 203, and are sandwiched by the ejector plates 211 and 212. The ejector plates 211 and 212 are supported with respect to the movable mold 34 so as to be able to advance and retract in the accommodating portion Sp1 formed in the spacer block 114. Accordingly, when the ejector motor 44 (FIG. 2) is driven and the rotational movement of the ejector motor 44 is converted into a linear motion by a motion direction changing mechanism (not shown) to advance the ejector plates 211 and 212, the sprue lock pin 202 and The ejector pin 203 can be advanced. The sprue lock pin 202, the ejector pin 203, the ejector plates 211 and 212, the protrusion motor 44, the movement direction conversion mechanism, and the like constitute a protrusion device.

  An undercut 230 is formed at the tip of the sprue lock pin 202, and the undercut 230 holds the molded product 81 when the mold is opened, and the resin solidified in the sprue 120, that is, sprue resin The sprue bushing 113 is pulled out. After the mold opening is performed, the sprue lock pin 202 functions as an ejector pin and protrudes sprue resin.

  By the way, as described above, in the present embodiment, the hole 82 is formed in the molded product 81, and the convex portion 82P having a circular shape is formed at a location corresponding to the hole 82 in the core Cmi. It has become. Therefore, as shown in FIG. 15, the molten resin flows in the cavity space Cv in the direction of arrow D, hits the convex portion 82P, is divided (molten resin Re1, Re2), flows around the convex portion 82P, It merges at the portion opposite to the mold inlet p2, that is, at the merge portion p3.

  Then, the flow fronts hd1 and hd2 of the molten resins Re1 and Re2 reach the merged portion p3 in a substantially solidified state similarly to the skin layers sk1 and sk2 formed in contact with the inner peripheral surface of the cavity space Cv, When solidified as it is, a weld Wd is formed at the joining portion p3, and a weld line Ln is formed on the molded product 81 by the weld Wd as shown in FIG. In that case, the bending strength becomes low or cracks occur, the mechanical strength of the molded product 81 becomes low, and the durability decreases.

  Therefore, in the present embodiment, a predetermined portion of the core Cmi, in this embodiment, in the vicinity of the joining portion p3 where the weld Wd is formed in the cavity space Cv, is opposed to the recess 83Q, and the cavity A resin reservoir 231 as a molding material reservoir is formed in communication with the space Cv, and the molten resin in the resin reservoir 231 is pushed into the cavity space Cv at a predetermined timing immediately before the weld Wd is formed in the cavity space Cv. At the same time, the molten resin in the cavity space Cv is caused to flow back into the heating cylinder 21 (FIG. 2) via the gate 172, the runner 171 and the sprue 120. It should be noted that a predetermined timing immediately before the weld Wd is formed in the cavity space Cv, that is, the molten resin in the resin reservoir 231 is pushed into the cavity space Cv, and the molten resin in the cavity space Cv is gated 172 and the runner 171. The timing of backflow into the heating cylinder 21 via the sprue 120 is set by performing a simulation, operating the injection molding machine 10 and molding the molded product 81.

  For this purpose, the push-in pin 251 is disposed so as to be able to advance and retreat with the ejector plates 211 and 212 and the movable mold 34 penetrating and with the tip facing the resin reservoir 231. Further, the head portion 253 formed at the rear end portion of the push pin 251 is sandwiched between the push plates 261 and 262. The pushing plates 261 and 262 are supported with respect to the movable mold 34 so as to be able to advance and retreat in a housing portion Sp2 formed in the spacer block 114 behind the housing portion Sp1. Accordingly, the pusher motor 45 (FIG. 2) is driven, and the pusher pin 251 is moved forward by converting the rotational motion of the pusher motor 45 into a straight motion by a motion direction changing mechanism (not shown). You can move forward. Note that a molding material pushing device is constituted by the pushing pins 251, the pushing plates 261 and 262, the pushing motor 45, the movement direction changing mechanism, and the like.

  Further, when the push pin 251 is advanced, the screw 22 is rotated in the reverse direction in the injection device 11 so that the front and the rear of the screw head 61 are not communicated with each other. By pulling back by the amount, suckback is performed.

  At this time, the molten resin in the resin reservoir 231 is pushed into the cavity space Cv, and the molten resin in the cavity space Cv is caused to flow back into the heating cylinder 21, so that as shown in FIG. In the merged portion p3, a pressure difference is formed between the portion ε1 on the side close to the resin reservoir 231 and the portion ε2 on the side far from the resin reservoir 231. Therefore, since the molten resin before solidification immediately before the weld Wd is formed is caused to flow so as to cross the merged portion p3, it is possible to prevent the weld Wd from being formed in the merged portion p3. Further, even if the weld Wd is formed, the weld Wd can be eliminated. As a result, the mechanical strength and elastic modulus of the molded product 81 can be increased. In FIG. 19, reference numeral 241 denotes a molten resin skin layer, and reference numeral 243 denotes a molten resin flow crossing the merged portion p3.

  Further, after the suckback is performed, the screw 22 is advanced while the front and rear of the screw head 61 are not connected to each other, so that the suckback is returned and the pressure in the cavity space Cv is increased. As a result, it is possible not only to prevent the occurrence of sink marks or the like in the molded product 81 but also to further increase the mechanical strength and elastic modulus of the molded product 81.

  Further, after the suck back is performed, the screw 22 is pushed forward to perform pressure holding. Therefore, even if the molten resin is solidified in the cavity space Cv and contracts, the pressure in the cavity space Cv does not decrease. As a result, the quality of the molded product 81 can be improved.

  In addition, the induction heating of the mold apparatus 12 is turned on from the start of mold closing to the end of holding pressure, and an induced current is applied to the coil 53 according to the temperature detected by the sensor 57 (FIG. 4). The temperature of the molten resin in the heating cylinder 21 and the temperature of the molten resin in the cavity space Cv are set to a predetermined temperature, which is 360 [° C.] in the present embodiment. And the temperature of the molten resin in the cavity space Cv are set within a set range, in this embodiment, 0 [°].

  Therefore, the pushing pin 251 is advanced, the molten resin in the resin reservoir 231 is pushed into the cavity space Cv, the screw 22 is retracted in the heating cylinder 21, and the molten resin in the cavity space Cv is heated in the heating cylinder 21. Since the temperature of the molten resin in the heating cylinder 21 and the temperature of the molten resin in the cavity space Cv are equalized when being flown back into the inside, the flow of molten resin 243 that crosses the junction p3 is reliably generated. Can be made.

  In addition, the induction heating of the mold apparatus 12 is turned off from the start of the cooling of the mold apparatus 12 to the end of the mold opening, and the mold apparatus 12 is cooled by the cooling chiller. The temperature of 12 is set to 180 [°] to 220 [°].

  Next, the operation of the injection molding machine 10 will be described.

  FIG. 20 is a time chart for explaining the operation of the injection molding machine according to the first embodiment of the present invention.

  First, in the fixed mold 33 (FIG. 2), the control unit 51 (FIG. 4) drives the mold clamping motor 48 to extend the toggle mechanism 43 at the timing t <b> 0 so that the movable platen 39 faces the fixed platen 36. Move forward and close the mold. When the movable mold 34 comes into contact with the fixed mold 33, the controller 51 further drives the mold clamping motor 48 to extend the toggle mechanism 43, presses the movable mold 34 against the fixed mold 33, and clamps the mold. Do. At this time, the movable mold 34 is pressed against the fixed mold 33 by the toggle mechanism 43 with a mold clamping force corresponding to the toggle magnification. A cavity space Cv is formed between the movable mold 34 and the fixed mold 33.

  Then, at the timing t0, the control unit 51 supplies an induction current to the coil 53, turns on induction heating of the mold apparatus 12, heats the inserts 122 and 142, and melts the molten resin in the cavity space Cv. Keep temperature at a constant value. For this purpose, the sensor 57 detects the temperature of the molten resin and sends it to the control unit 51, and the control unit 51 controls the value of the induced current supplied to the coil 53 according to the detected temperature.

  Further, the control unit 51 opens the control valve 55 at the timing t0, supplies the cooling chiller from the cooling chiller supply source to the flow paths 136 to 139 and 156 to 159, and sets the fixed mold 33 and the movable mold 34 to each other. Cooling.

  Subsequently, at timing t1, the control unit 51 finishes the mold clamping, drives the injection motor 32 to advance the screw 22 at a set speed, and injects the molten resin stored in front of the screw 22 from the injection nozzle 24. Then, the cavity space Cv in the mold apparatus 12 is filled. The sensor 56 detects the temperature of the molten resin stored in front of the screw 22 and sends it to the control unit 51. The control unit 51 determines the value of the current supplied to the heater 26 according to the detected temperature. To control.

  Then, the control unit 51 drives the push motor 45 and advances the push pin 251 at the timing t2 before the weld Wd is formed in the cavity space Cv.

  Further, at timing t2, the control unit 51 drives the metering motor 31 in the injection device 11 to rotate the screw 22 in the reverse direction, and in the communication mechanism, the front and rear of the screw head 61 are disconnected from each other. Thus, the sucking back is performed by driving the injection motor 32 and retracting the screw 22 by a predetermined amount without rotating it. That is, the control unit 51 drives the push motor 45 to synchronize the timing for moving the push pin 251 forward with the timing for moving the screw 22 backward by a predetermined amount without rotating it.

  As a result, the molten resin in the resin reservoir 231 is pushed into the cavity space Cv, and the molten resin in the cavity space Cv is caused to flow back into the heating cylinder 21. As a result, a molten resin flow 243 that crosses the joining portion p3 in the cavity space Cv is formed, and the formation of the weld Wd is prevented.

  In addition, after the suck back pull is performed, the control unit 51 drives the injection motor 32 and advances the screw 22 while the front and the rear of the screw head 61 are disconnected from each other at the timing t3. Perform back-back.

  Further, after performing the suckback return, the control unit 51 drives the injection motor 32 and pushes the screw 22 forward to hold the pressure at timing t4.

  Subsequently, when the predetermined time has elapsed and the holding pressure is finished, the control unit 51 stops the supply of the induction current to the coil 53 at timing t5, turns off the induction heating of the mold apparatus 12, and fixes it. Cooling of the mold 33 and the movable mold 34 is started, and the metering motor 31 is driven in the injection device 11 to rotate the screw 22 to perform metering.

  Then, when the metering is finished at timing t6, the control unit 51 drives the metering motor 31 again, rotates the screw 22 in the reverse direction, disconnects the front and rear of the screw head 61, and subsequently, The injection motor 32 is driven, and the suckback is performed by retracting a predetermined amount without rotating the screw 22.

  As a result, the screw 22 is retracted by a small amount without being rotated, the pressure of the molten resin stored in front of the screw 22 is lowered, and the molten resin droops into the sprue 120 from the tip of the injection nozzle 24, It is prevented from solidifying.

  Subsequently, when a predetermined time elapses and the cooling is finished, the control unit 51 finishes the suck back pulling at the timing t7, drives the mold clamping motor 48 to contract the toggle mechanism 43, and moves the movable platen 39. The mold is released from the fixed platen 35 and the mold is opened.

  When the mold opening is completed, the control unit 51 drives the protruding motor 44 at the timing t8 to advance the sprue lock pin 202 and the ejector pin 203, thereby protruding the molded product 81.

  When projecting the molded product 81 in this way, the control unit 51 drives the injection motor 32 and advances the screw 22 at time t9 to drive back the suck back and drive the pushing motor 45. The push pin 251 is retracted. Further, at the timing t9, the control unit 51 supplies an induction current to the coil 53, turns on the induction heating of the mold apparatus 12, and heats the inserts 122 and 142 again.

  Subsequently, when the suck back is returned and the pushing pin 251 is moved backward, the control unit 51 starts molding of the next cycle at timing t10, advances the movable platen 39 toward the fixed platen 36, and closes the mold. At the same time, the movable mold 34 is pressed against the fixed mold 33 to perform mold clamping.

  As described above, in the present embodiment, the molten resin is divided in the cavity space Cv, and immediately before the molten resin is merged at the merged portion p3, the push pin 251 is advanced, and the molten resin in the resin reservoir 231 is Since the molten resin in the cavity space Cv is pushed into the space Cv, the molten resin in the cavity space Cv is caused to flow back into the heating cylinder 21, and then the screw 22 is advanced to increase the pressure of the molten resin in the cavity space Cv. A sufficient flow 243 of molten resin can be formed across the junction p3.

  Therefore, it is possible to prevent the weld Wd from being formed in the merged portion p3, so that the mechanical strength and elastic modulus of the molded product 81 can be increased. As a result, the durability of the molded product 81 can be improved.

  By the way, in the present embodiment, a thermoplastic resin is used as a molding material, but a liquid crystal polymer such as a liquid crystalline polyester having a linear molecular structure or a liquid crystalline polyamide is used as the molding material. can do. A liquid crystal polymer is composed of a rigid polymer, and even when melted, the molecular chain is not easily bent, maintains a rod-like shape, has crystal properties, has little entanglement of molecules when melted, and has a slight shear force. Just receiving it, the molecules are oriented in one direction. And when it cools, it has the property that a molecule | numerator solidifies with orientation and the state which the molecule | numerator orientated to one direction is hold | maintained stably.

  From this, when the molded product is molded using the liquid crystal polymer, the linear molecules are aligned linearly in the flow direction of the molten resin due to the injection pressure in the injection device 11, so that the mechanical property of the molded product 81 in the alignment direction is Strength and elastic modulus can be increased.

  Moreover, when fillers such as fibers, amorphous particles, and needle whiskers are mixed in the liquid crystal polymer, linear molecules are linearly aligned in the flow direction of the molten resin by the injection pressure in the injection device 11, and reinforcing fibers are also formed. Since it is oriented, the mechanical strength and elastic modulus of the molded product 81 can be further increased.

  However, when the molded product 81 is molded using the liquid crystal polymer, the molten resin that has entered the cavity space Cv is divided and merged to form a weld Wd. Since the entanglement is extremely small, the mechanical strength of the molded article 81 is lowered and the durability is lowered as compared with the case where a resin other than the liquid crystal polymer, for example, a thermoplastic resin is used.

  In the present embodiment, as described above, immediately before the weld Wd is formed in the cavity space Cv, the molten resin in the resin reservoir 231 is pushed into the cavity space Cv and the melt in the cavity space Cv. Since the resin is allowed to flow back into the heating cylinder 21 through the gate 172, the runner 171 and the sprue 120, the mechanical strength and elastic modulus of the molded article 81 can be increased even when a liquid crystal polymer is used as the molding material. it can.

  By the way, in the present embodiment, one gate 172 is arranged in one cavity space Cv. However, a plurality of gates are arranged in one cavity space Cv, and each gate is interposed. May be filled with molten resin.

  For example, when molding a molded product used for mobile product parts, such as a connector for a flexible printed circuit (FPC), a lens frame of a camera module, etc., the molded product is extremely thin and the mounting height is possible. As low as possible. In that case, since warpage is likely to occur in the molded product, a plurality of gates (submarine gates) are arranged in one cavity space Cv in order to prevent the warpage from occurring. Thus, the molten resin that has entered the cavity space Cv merges at a plurality of locations, and a plurality of welds Wd are formed.

  Therefore, when a plurality of gates are provided for one cavity space Cv, a plurality of resin reservoirs are formed in one cavity space Cv to prevent the formation of weld Wd. A second embodiment of the invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 21 is a fragmentary cross-sectional view of a mold apparatus according to the second embodiment of the present invention.

  In the drawing, 171 and 271 are runners, 172 and 272 are gates, 231 is a resin reservoir as a first molding material reservoir portion formed in communication with the cavity space Cv and corresponding to the gate 172, 331. Is a resin reservoir as a second molding material reservoir formed in communication with the cavity space Cv and corresponding to the gate 272. Further, reference numeral 251 denotes a pressing pin as a first pressing member and a first actuator disposed with the tip thereof facing the resin reservoir 231, and reference numeral 351 denotes a tip of the resin reservoir 331. The head portions 253 and 353 formed at the rear end portions of the push pins 251 and 351 are the push pins as the second push member and the second actuator disposed as shown in FIG. 262.

  In this case, even if the molten resin that has entered the cavity space Cv through the gates 172 and 272 joins at a plurality of locations, it is possible to prevent the weld Wd from being formed.

  Incidentally, in each of the embodiments described above, the resin reservoirs 231 and 331 are formed in the cavity space Cv, but a resin reservoir can also be formed in the runner.

  Next, a third embodiment of the present invention in which a resin reservoir is formed in the runner will be described. In addition, about the thing which has the same structure as 1st, 2nd embodiment, the same code | symbol is provided and the effect of the embodiment is used about the effect of the invention by having the same structure.

  FIG. 22 is a cross-sectional view of an essential part of a mold apparatus according to the third embodiment of the present invention.

  In the figure, reference numeral 431 denotes a resin reservoir as a molding material reservoir formed in the runner 271 in communication with the cavity space Cv, and reference numeral 451 denotes a pushing member disposed with the tip thereof facing the resin reservoir 431. The head portion 453 formed at the rear end of the push pin 451 is sandwiched between the push plates 261 and 262.

  By the way, in each of the above embodiments, when the molten resin in the resin reservoirs 231, 331, 431 is pushed into the cavity space Cv by the push pins 251, 351, 451, a pressure difference is formed in the molten resin, and the molten resin A flow 243 (FIG. 19) crossing the merging portion p3 (FIG. 14) is formed. However, for example, when a portion having a large cross-sectional area exists in the cavity space Cv, the molten resin is guided to a portion having a large cross-sectional area. Thus, the pressure difference may not be formed. In that case, it becomes impossible to form the flow 243 that crosses the joining portion p3 of the molten resin, and the weld Wd is formed in the joining portion p3 of the molten resin.

  Therefore, it is possible to control the flow of the molten resin in the cavity space Cv, prevent the molten resin from being guided to a portion having a large cross-sectional area, and form a flow crossing the merged portion p3 of the molten resin. A fourth embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st-3rd embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 23 is a cross-sectional view of an essential part of a mold apparatus according to the fourth embodiment of the present invention.

  In the figure, reference numeral 255 denotes a flow control pin as an in-mold flow control member which is disposed so as to freely advance and retreat at a predetermined location in the cavity space Cv. The flow control pin 255 moves the cavity when the push pin 251 as the push member and the actuator is advanced and the molten resin in the resin pool 231 as the molding material pool portion is pushed into the cavity space Cv. The flow of the molten resin in the space Cv is controlled.

  For this purpose, the flow control pin 255 is disposed through the push-in plates 261 and 262, the ejector plates 211 and 212, and the movable mold 34, with the tip facing the cavity space Cv. The head portion 283 formed at the rear end portion of the flow control pin 255 is sandwiched between the resin flow control plates 291 and 292.

  The flow control pin 255 is advanced at a predetermined timing immediately before the push pin 251 is advanced when a portion having a large cross-sectional area exists in the cavity space Cv, and is protruded into the cavity space Cv. 251 prevents the molten resin pushed into the cavity space Cv from the resin reservoir 231 from being guided to a portion having a large cross-sectional area, and forcibly sends the molten resin to the joining portion p3. Therefore, it is possible to reliably form the flow 243 that crosses the joining portion p3 of the molten resin.

  The flow control pin 255 is configured such that the molten resin in the resin reservoir 231 is pushed into the cavity space Cv, and the molten resin in the cavity space Cv passes through the gate 172, the runner 171 and the sprue 120 and is a heating cylinder as a cylinder member. After being made to flow backward in 21, the screw 22 as the injection member is retracted at a timing before being advanced again.

  By the way, in the present embodiment, when a portion having a large cross-sectional area exists in the cavity space Cv, the molten resin is prevented from being guided to a portion having a large cross-sectional area. When a portion having a small cross-sectional area exists in Cv, the flow resistance of the molten resin at the portion having a small cross-sectional area increases, and a pressure difference may not be formed. In that case, it becomes impossible to form the flow 243 that crosses the joining portion p3 of the molten resin, and the weld Wd is formed in the joining portion p3 of the molten resin.

  Therefore, the flow control pin 255 can be used in order to reduce the flow resistance of the molten resin at a portion having a small cross-sectional area.

  The flow control pin 255 is retracted at a predetermined timing immediately before the push pin 251 is advanced when there is a portion having a small cross-sectional area in the cavity space Cv. As a result, a resin reservoir is formed in front of the flow control pin 255, and the molten resin in the cavity space Cv is guided into the resin reservoir to form a pressure difference. As a result, a flow crossing the merged portion p3 of the molten resin can be reliably formed.

  In the present embodiment, the flow control pin 255 is used as the in-mold flow control member, but a flow control piece can be used instead of the flow control pin 255.

  The present invention is not limited to the above embodiments, and various modifications can be made based on the gist of the present invention, and they are not excluded from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Injection molding machine 11 Injection apparatus 12 Mold apparatus 21 Heating cylinder 22 Screw 23 Drive apparatus 33 Fixed mold 34 Movable mold 45 Pushing motor 51 Control part 61 Screw head 67 1st ring 68 2nd rings 231, 331, 431 Resin Reservoir 251, 351, 451 Push pin 261, 262 Push plate Cv Cavity space

Claims (15)

(A) A cylinder member, an injection member that is rotatably and reciprocatingly disposed in the cylinder member, and that has a head portion at a tip thereof, and a communication mechanism that selectively communicates the front and rear of the head portion And an injection device provided with a drive device for rotating and advancing and retracting the injection member;
(B) A first mold and a second mold disposed so as to be able to contact with and separate from the first mold are provided, and the second mold is brought into contact with the first mold. A mold apparatus for forming a cavity space between the first and second molds,
(C) a molding material reservoir formed in communication with the cavity space, and a pushing member disposed so as to be able to advance and retreat with the tip facing, and a pushing drive unit for moving the pushing member forward and backward. Molding material pushing device,
(D) Immediately before the injection member is advanced in the cylinder member, the molten molding material is injected, the cavity space is filled, the molding material is divided in the cavity space, and just before joining at the joining portion. The pushing member is moved forward to push the molding material in the molding material reservoir into the cavity space, the injection member is retracted in the cylinder member, and the molding material in the cavity space is caused to flow back into the cylinder member. An injection molding machine comprising: a controller that increases the pressure of the molding material in the cavity space by advancing the injection member in the cylinder member.   The control unit sets a difference between the temperature of the molten molding material in the cylinder member and the temperature of the molding material in the cavity space at a timing at which the molding material in the cavity space flows back into the cylinder member. The injection molding machine according to claim 1, wherein the injection molding machine is placed inside.   The injection molding machine according to claim 2, wherein the mold apparatus includes a coil for induction heating in order to heat the molding material in the cavity space.   The controller advances the pushing member to push the molding material in the molding material reservoir into the cavity space, and retracts the injection member in the cylinder member to bring the molding material in the cavity space into the cylinder member. The injection molding machine according to any one of claims 1 to 3, wherein the timing of backflow is synchronized.   5. The control unit according to claim 1, wherein the control unit disconnects the front and the rear from the head unit in the communication mechanism at a timing at which the molding material in the cavity space flows back into the cylinder member. The injection molding machine described.   The injection molding machine according to any one of claims 1 to 5, wherein the molding material reservoir is formed in the cavity space.   The injection molding machine according to claim 1, wherein the molding material reservoir is formed on a runner for supplying molding material to the cavity space.   The injection molding machine according to any one of claims 1 to 7, wherein the mold apparatus includes a plurality of gates for one cavity space.   The injection molding machine according to any one of claims 1 to 8, wherein a plurality of the molding material reservoirs are formed in one cavity space.   The in-mold flow control member that controls the flow of the molding material in the cavity space when the pushing member is advanced and the molding material in the molding material reservoir is pushed into the cavity space. The injection molding machine according to item 1.   The injection molding machine according to claim 10, wherein the control unit advances the in-mold flow control member to control the flow of the molding material in the cavity space.   The injection molding machine according to claim 10, wherein the control unit retracts the in-mold flow control member to control the flow of the molding material in the cavity space.   The injection molding machine according to any one of claims 1 to 12, wherein the molding material is a liquid crystal polymer having a linear molecular structure.   The injection molding machine according to claim 13, wherein a filler is mixed into the molding material. (A) The injection member is advanced in the cylinder member to inject the molten molding material, and fill the cavity space of the mold apparatus;
(B) In the cavity space, the melted molding material is diverted, and at the timing just before joining at the joining portion, the pushing member is advanced in the molding material reservoir portion formed in communication with the cavity space, The molding material in the molding material reservoir is pushed into the cavity space, the injection member is retracted in the cylinder member, and the molding material in the cavity space is caused to flow back into the cylinder member,
(C) An injection molding method characterized in that the pressure of the molten molding material in the cavity space is increased by moving the injection member forward in the cylinder member.

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