Molding apparatus and molding method

Abstract

To provide a molding apparatus capable of effectively preventing a resin material from leaking from a resin flow path, and a molding method using the molding apparatus.SOLUTION: An injection molding machine 1 has a gate 21, a resin flow path 22, and a valve pin 23. The gate 21 is disposed at the vicinity of a first end portion 22a of the resin flow path 22. The resin flow path 22 is formed with a through hole 22c that allows the valve pin 23 to penetrate the inside of the flow path and the outside of the flow path. The valve pin 23 realizes a closed state in which the gate 21 is closed from the inside of the resin flow path 22 by an advancing movement and an opened state in which the gate 21 is opened by a retraction movement to enable injection of a resin material 6 from the gate 21. A diaphragm 24 for sealing the through hole 22c to block the inside and the outside of the resin flow path 22 is disposed at the vicinity of the through hole 22c. The diaphragm 24 is at least partially fixed to the valve pin 23, and is deformable in accordance with forward and backward movement of the valve pin.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a molding apparatus and a molding method, and more particularly to a molding apparatus for runnerless molding using a resin material. [Background technology]

[0002] Plastic injection molding technology is used in various industrial fields as a means of manufacturing and shaping products and parts, and is expanding into fields that require high precision. In such injection molding, molds play an important role along with molding machines.

[0003] In recent years, various attempts have been made in the field of injection molding to make more efficient use of resources, such as resource saving and recycling. Among these, the runnerless molding method, which keeps the resin in the runner at a viscosity that allows it to be injected, has become widely adopted.

[0004] In runnerless molding, resin maintained at an injectable viscosity is directly injected from an outlet (gate) on the fixed mold side into the gap (inside the mold) formed by the fixed mold and the movable mold. In the fixed mold, the sprue and runner are kept in an injectable state by temperature control in the sprue flow path and the runner flow path even after the resin is injected, so solid sprues and runners that are generated as by-products in conventional molding are not generated (for example, Patent Document 1). Runnerless molding, which does not generate sprues and runners, is advantageous from the viewpoints of resource conservation and cost reduction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-160265 A Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional runnerless molding, a valve pin is placed inside a hollow probe (resin flow path) through which the resin material flows, and the gate is opened and closed by the up and down (or back and forth) movement of the valve pin. The valve pin opens and closes the gate from inside the resin flow path. However, because the drive source that operates the valve pin is placed outside the resin flow path, the valve pin is placed penetrating from the inside to the outside of the resin flow path.

[0007] A through hole for inserting the valve pin is formed in the middle of the resin flow path. The valve pin moves up and down or back and forth while fitted in the through hole. An issue was that the resin material leaked out of the resin flow path from the gap between the through hole and the valve pin. When introducing the resin material into the resin flow path or when injecting the resin material from the resin flow path into the mold, pressure is applied to the resin flow path, which makes the leakage of the resin material more noticeable, making it even more of an issue.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and has an exemplary object to provide a molding apparatus that can effectively prevent leakage of resin material from a resin flow path, and a molding method using the molding apparatus. [Means for solving the problem]

[0009] In order to solve the above problems, a molding apparatus as an exemplary aspect of the present invention has the following configuration.

[0010] an injection port for injecting a resin material into the mold; a resin flow path that guides the resin material to the injection port; a valve pin extending in a generally axial shape, capable of moving forward or backward along a direction in which the axis extends, and disposed midway through the resin flow path so as to penetrate an inside and an outside of the resin flow path, the injection port is disposed near a first end of the resin flow path that is closer to the inside of the mold, a through hole is formed in the resin flow path, through which the valve pin passes from the inside of the flow path to the outside of the flow path; the valve pin realizes a closed state in which the valve pin closes the injection port from inside the resin flow path by forward movement, and an open state in which the valve pin opens the injection port to allow the resin material to be injected from the injection port by backward movement, a sealing member is disposed near the through hole to seal the through hole and isolate the inside and outside of the resin flow path; At least a portion of the sealing member is fixed to the valve pin and is deformable in accordance with back and forth movement of the valve pin.

[0011] A molding method according to another exemplary aspect of the present invention has the following configuration.

[0012] A molding method using the molding apparatus described above, an opening step of moving the valve pin backward from the closed state in which the resin material is filled in the resin flow path to the open state; an injection step of applying a positive pressure to the resin material in the resin flow path after the opening step to inject the resin material into the mold; a depressurization step of applying a negative pressure to the resin material in the resin flow path after the injection step; and a closing step of moving the valve pin forward to achieve the closed state, after or together with the depressurizing step.

[0013] Further objects and other features of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. Effect of the Invention

[0014] According to the present invention, it is possible to provide a molding apparatus capable of effectively preventing leakage of resin material from a resin flow path, and a molding method using the molding apparatus. [Brief description of the drawings]

[0015] [Figure 1] 1 is an overall configuration diagram of an injection molding machine according to an embodiment of the present invention; [Diagram 2] 2 is a schematic diagram showing a fixed mold and its periphery attached to the injection molding machine of FIG. 1. [Diagram 3] FIG. 3 is a front view showing the valve pin of FIG. 2 together with a diaphragm. [Figure 4] FIG. 3 is an exploded perspective view showing an assembly state of the valve pin and the diaphragm in FIG. 2. [Diagram 5] 3A and 3B are enlarged partial cross-sectional views showing the vicinity of a diaphragm in a state in which the valve pin in FIG. 2 is attached to an injection molding machine, in which (a) shows a gate in an open state and (b) shows a gate in a closed state. [Figure 6] 4 is a flowchart illustrating a resin molding method using an injection molding machine according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Embodiment] <Injection molding machine 1> Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an injection molding machine (molding device) 1 according to an embodiment. The injection molding machine 1 is a molding device for performing runnerless molding. The injection molding machine 1 has a press device 2, and is configured so that a fixed mold (mold with a built-in runnerless device) 3 and a movable mold 4 can be attached. Note that the molding device of the present invention is not necessarily limited to an injection molding machine for runnerless molding. The present invention can be applied to injection molding machines other than those for runnerless molding, and to various resin molding machines other than injection molding.

[0017] The fixed mold 3 is clamped together with the movable mold 4 to form a space 10 for a resin molded product, and is the side that is attached to the injection molding machine 1 by the press device 2, i.e., the side that is not moved by the press device 2. The fixed mold 3 is configured to have, for example, a mounting plate 11, a manifold 12, a back plate 13, and a cavity plate 14.

[0018] A hollow bush 1b is attached to the mounting plate 11, and resin material 6 supplied from a nozzle 1a by a dispenser (material supply means) 5 (described later) flows from the bush 1b into the inside of a resin flow path 22.

[0019] Nozzle 1a of dispenser 5 is joined to stationary mold 3 via bushing 1b. Resin material 6 supplied by dispenser 5 from a resin material tank (not shown) reaches stationary mold 3 and flows inside resin flow path 22. Resin material 6 flowing inside resin flow path 22 is injected (discharged) through gate (injection port) 21 into space 10 defined by stationary mold 3 and movable mold 4. Note that, since injection molding is explained in this specification, discharge and injection are used as substantially the same meaning.

[0020] The movable die 4 can be moved relative to the fixed die 3 by the press device 2. With the movable die 4 moved so as to come into close contact with the fixed die 3 and clamped, a resin material 6 is injected into a gap (inside the die) 10 formed between both dies, and a resin molded product is produced according to the shape of the gap 10. The press device 2 is constituted by an actuator such as a hydraulic cylinder or a servo motor, and clamps the die with a press pressure of several tens to several hundreds of tons.

[0021] Note that other components of the injection molding machine, such as a resin material tank, are publicly known, and therefore illustrations and explanations are omitted. Also, with regard to the resin molding process in runnerless molding, the parts related to the present invention will be explained below, but other parts are publicly known, and therefore explanations are omitted. Also, in Fig. 1, for ease of understanding, details of the structure near through hole 22c (described later) and details of components arranged therein are omitted and shown in a simplified manner.

[0022] 2 is a schematic diagram showing the fixed mold 3 and its periphery attached to the injection molding machine 1. The injection molding machine 1 has a gate (injection port) 21, a resin flow path 22, and a valve pin .

[0023] In order to distinguish between the fixed mold 3, which has the mounting plate 11, manifold 12, back plate 13, and cavity plate 14 and in which the resin flow path 22 is formed, and the valve pin 23, which is arranged across the inside and outside of the resin flow path 22 but can move back and forth (up and down) independently of the fixed mold 3, components such as the mounting plate 11, manifold 12, back plate 13, cavity plate 14, and resin flow path 22 (i.e., components that do not operate synchronously with the valve pin 23) may be collectively referred to as "components on the fixed mold 3 side."

[0024] The gate 21 is an injection port for injecting the resin material 6 in the resin flow path 22 toward the gap 10. The gate 21 is disposed near a first end 22a of the resin flow path 22. The first end 22a is the end closer to the gap 10 among a plurality of ends of the resin flow path 22. The gate 21 is a hole formed near the first end 22a of the resin flow path 22, and is configured to be opened and closed by the back and forth movement of a valve pin 23 described later.

[0025] The resin material 6 is supplied into the resin flow path 22 by the dispenser 5 from a second end 22b different from the first end 22a. The second end 22b is the end farther from the gap 10 among the multiple ends of the resin flow path 22. The resin material 6 is heated by a heater (not shown) (or is not heated depending on the type of resin material) and has fluidity. The resin material 6 is supplied into the resin flow path 22 by applying a predetermined positive pressure to the resin material 6 by the dispenser 5.

[0026] The resin flow path 22 is a flow path that guides the resin material 6 supplied by the dispenser 5 to the gate 21. As shown in Fig. 1, in this embodiment, the resin flow path 22 has one second end 22b and two first ends 22a after branching into two. The resin material 6 supplied from the second end 22b passes through the inside of the resin flow path 22 and is injected into the gap 10 from each of the two gates 21 arranged near the two first ends 22a.

[0027] A through hole 22c for passing the valve pin 23 therethrough is formed in the middle of the resin flow path 22. In this embodiment, the through hole 22c is formed at two locations corresponding to the two gates 21. The through hole 22c allows the valve pin 23, which will be described later, to pass through and be disposed so that the valve pin 23 communicates with the inside and outside of the resin flow path 22.

[0028] <Valve pin 23> Fig. 3 is a front view showing the valve pin 23 together with the diaphragm 24, and Fig. 4 is an exploded perspective view showing the assembly of the valve pin 23 and the diaphragm 24. Fig. 5 is an enlarged partial cross-sectional view showing the vicinity of the diaphragm 24 as a sealing member with the valve pin 23 attached to the injection molding machine 1, where (a) shows the open state of the gate 21 and (b) shows the closed state of the gate.

[0029] As shown in Figs. 3 and 4, the valve pin 23 is an axial member having a roughly axial shape, and is generally made of metal. The valve pin 23 is disposed inside the resin flow path 22 with its tip end 23a facing the gate 21, and a part of it passes through a through hole 22c formed in the middle of the resin flow path 22 and is disposed outside the resin flow path 22. The rear end 23b disposed outside the resin flow path 22 is connected or coupled to the driving means M1, and the valve pin 23 can be moved back and forth by the driving means M1 along the direction in which the axis extends (the direction of the arrow X in Fig. 3). The moving direction of the valve pin 23 is expressed as a front-rear direction and a vertical direction. The downward direction in Fig. 3 is the forward direction, and the upward direction is the backward direction.

[0030] 3 illustrates an example in which the diameter of the rear end 23b of the valve pin 23 is larger than the diameter of the entire main body shaft portion of the valve pin 23. How to form this rear end 23b is adjusted appropriately depending on design or manufacturing considerations. For example, a smaller diameter portion (the main body shaft portion of the valve pin 23 and the vicinity of the tip portion 23a) may be formed by cutting or grinding a cylinder with the same diameter as the diameter of the rear end 23b.

[0031] In order to further reduce processing costs and simplify the manufacturing process, for example, rear end 23b may be formed with a nut, and the corresponding portion on the shaft side of the valve pin 23 may be threaded, and rear end 23b as a nut may be screwed onto the thread on the shaft side of the valve pin 23 to secure it.

[0032] When the valve pin 23 has moved forward, the gate 21 is in a closed state. In this closed state, the tip 23a of the valve pin 23 closes the gate 21 from inside the resin flow path 22, and the resin material 6 is not injected from the gate 21 into the gap 10. When the valve pin 23 has moved backward, the gate 21 is in an open state. In this open state, the tip 23a of the valve pin 23 has moved backward toward the inside of the resin flow path 22 (i.e., above the gate 21 in FIG. 3) to open the gate 21, and the resin material 6 can be injected from the gate 21 into the gap 10.

[0033] <Diaphragm 24> A diaphragm 24 is attached to the valve pin 23. The diaphragm 24 is a member for preventing the resin material 6 in the resin flow path 22 from leaking out of the resin flow path 22 through the through hole 22c. The shape of the diaphragm 24 is not particularly limited as long as it is a shape that can prevent the resin material 6 from leaking out of the through hole 22c, but in this embodiment, it is a donut shape (ring shape). The diaphragm 24 has an opening hole 24a near its center that has approximately the same diameter as the shaft diameter of the valve pin 23, and an outer edge 24b is a circle with a predetermined diameter that is larger than the opening hole 24a.

[0034] The material of the diaphragm 24 is appropriately selected depending on the design of the injection molding machine 1 and the characteristics of the resin material 6 used, and for example, an elastic material such as a rubber material such as urethane rubber, natural rubber, butyl rubber, nitrile rubber, fluororubber, silicone rubber, etc. Also, as long as it allows the deformation of the diaphragm 24 as described later, the diaphragm 24 may be formed from, for example, a thin plate of metal or resin. Examples of the metal material include iron, stainless steel, aluminum, copper, or alloys thereof, or alloys of these with zinc, tin, etc.

[0035] Valve pin 23 has a stepped portion 23c that protrudes from the shaft portion to the outer periphery, and diaphragm 24 is fixed to valve pin 23 by stepped portion 23c and nut 25. Opening hole 24a of diaphragm 24 is tightly closed by stepped portion 23c and nut 25, preventing resin material 6 from leaking from the inside of resin flow path 22 to the outside from the vicinity of opening hole 24a of diaphragm 24.

[0036] Here, in order to prevent the diaphragm 24 from rotating with the rotation of the nut 25, it is preferable to sandwich a washer 26 between the nut 25 and the diaphragm 24 (see FIG. 4). In this case, the nut 25, the washer 26, and the stepped portion 23c cooperate to tightly close the opening hole 24a of the diaphragm 24.

[0037] The method of fixing the diaphragm 24 to the valve pin 23 is not limited to the method described above. For example, it is also possible to use a so-called double nut method in which the stepped portion 23c is not formed on the valve pin 23 and the diaphragm 24 is fixed to the valve pin 23 by fastening two nuts 25 to each other from both sides.

[0038] In addition, in FIG. 4, an example in which the stepped portion 23c protruding from the shaft portion to the outer periphery is formed has been described, but this is not limited thereto. A step having a smaller diameter from the rear end portion 23b side toward the tip end portion 23a may be provided in the middle of the shaft portion of the valve pin 23 in the longitudinal direction. When a cylindrical ring member (having an inner diameter substantially the same as the diameter of the shaft portion on the side closer to the tip end portion 23a and an outer diameter larger than the diameter of the shaft portion on the side closer to the rear end portion 23b) is fitted and inserted from the tip end portion 23a side, it is locked at the stepped portion. Then, the outer diameter of the cylindrical ring member becomes the stepped portion 23c. Then, the stepped portion 23c and the nut 25 allow the diaphragm 24 to be fixed to the valve pin 23.

[0039] With this configuration, there is no need to form a portion of the shaft of the valve pin 23 that has a larger diameter than the other portions, which contributes to reducing the manufacturing costs of the valve pin 23 and the number of processes.

[0040] An outer edge 24b of the diaphragm 24 is fixed to the fixed mold 3. For example, as shown in Fig. 5, a fastening member 15 and a supporting member 16 may be arranged on an attachment plate 11 on the fixed mold 3 side, and the outer edge 24b of the diaphragm 24 may be tightly clamped by the fastening member 15 and the supporting member 16, thereby fixing the outer edge 24b of the diaphragm 24 to the fixed mold 3 side.

[0041] Here, the fastening member 15 and the support member 16 are members fixed to the fixed mold 3 side, and do not move back and forth in synchronization with the back and forth movement of the valve pin 23. An opening is formed in the center of both the fastening member 15 and the support member 16, through which the valve pin 23 passes so as to be movable back and forth. The outer edges of both the fastening member 15 and the support member 16 are fitted into a fitting recess 11a formed in the mounting plate 11. Therefore, the resin material 6 in the resin flow path 22 is prevented from leaking out of the resin flow path 22 from the vicinity of the outer edge 24b of the diaphragm 24 as well.

[0042] In this embodiment, the fastening member 15 and the support member 16 are described as separate members from the mounting plate 11, but of course at least one of them may be integrated with the mounting plate 11. Also, the fastening member 15 and the support member 16 only need to be arranged on the fixed mold 3 side, and may not necessarily be arranged in the mounting plate 11, but may be arranged, for example, in the manifold 12 or the back plate 13. In that case, the fitting recess 11a corresponding to the support member 16 etc. will also be formed in, for example, the manifold 12 or the back plate 13.

[0043] As described above, the opening 24a of the diaphragm 24 is tightly closed by the stepped portion 23c, the nut 25, and the washer 26, and the outer edge 24b is tightly closed by the fastening member 15 and the support member 16. As a result, the resin material 6 inside the resin flow path 22 is blocked by the diaphragm 24, and is prevented from leaking out to the outside of the resin flow path 22.

[0044] As described above, the diaphragm 24 is formed from an elastic material or a thin plate of a deformable metal, resin, or the like. Therefore, it is deformable in accordance with the forward and backward movement of the valve pin 23, and the tightness of the opening hole 24a and the tightness of the outer edge 24b of the diaphragm 24 are maintained whether the gate 21 is in a closed state due to the forward movement of the valve pin 23 or in an open state due to the backward movement of the valve pin 23. In other words, the inside and outside of the resin flow path 22 are kept isolated whether in the closed state or the open state.

[0045] <Support member 16> As shown in Fig. 5, the support member 16 has an opposing surface 16a that faces the diaphragm 24. The opposing surface 16a is shaped to fit the rear surface of the diaphragm 24 in the open state, and is typically an inclined surface as shown in Fig. 5.

[0046] When the valve pin 23 moves backward and the gate 21 is in the open state, the opposing surface 16a of the support member 16 is in contact with the rear surface of the diaphragm 24 or is located immediately behind it with a small gap. In this state, the diaphragm 24 is supported by the opposing surface 16a of the support member 16. In the open state, the opposing surface 16a supports the diaphragm 24 from outside the resin flow path 22, thereby restricting deformation of the diaphragm 24 outward from the resin flow path 22.

[0047] When the gate 21 is in an open state, the dispenser 5 pressurizes the resin material 6, and the resin material 6 in the resin flow path 22 is injected into the gap 10 through the gate 21. At this time, the inside of the resin flow path 22 is in a positive pressure state, and pressure toward the outside of the resin flow path 22 (i.e., toward the support member 16) is applied to the diaphragm 24. However, since the diaphragm 24 is supported by the opposing surface 16a of the support member 16, the diaphragm 24 is prevented from bearing unnecessary excessive pressure, and damage to the diaphragm 24 and leakage of the resin material 6 from the vicinity of the diaphragm 24 to the outside of the resin flow path 22 are prevented.

[0048] <Dispenser 5> The dispenser 5 is for supplying the resin material 6 from the nozzle 1a through the bushing 1b into the resin flow path 22. The dispenser 5 is, for example, composed of a compressor or an extruder having a hopper and a screw, but a detailed description thereof will be omitted.

[0049] The dispenser 5 of this embodiment is capable of applying negative pressure in addition to applying positive pressure to the resin material 6 in the resin flow path 22. That is, in addition to the operation of supplying the resin material 6 to the resin flow path 22 (application of positive pressure), it is also capable of performing a suction operation of drawing back the resin material 6 from the resin flow path 22 (application of negative pressure).

[0050] When the gate 21 transitions from an open state to a closed state by moving the valve pin 23 forward, the diaphragm 24 deforms, thereby reducing the internal volume of the resin flow path 22. If the volume of the resin material 6 present in the resin flow path 22 does not change, the pressure in the resin flow path 22 increases. At this time, since the diaphragm 24 is separated from the opposing surface 16a of the support member 16, the diaphragm 24 is exposed to high pressure, which has an adverse effect on the diaphragm 24 and may cause damage or leakage of the resin material 6.

[0051] However, if the dispenser 5 is capable of suction operation, the dispenser 5 can apply negative pressure to the resin material 6 in the resin flow path 22 when the valve pin 23 moves forward. By applying negative pressure, the resin material 6 in the resin flow path 22 is partially sucked in, preventing application of excessively high pressure to the diaphragm 24. As a result, damage to the diaphragm 24 and leakage of the resin material 6 from the inside to the outside of the resin flow path 22 are prevented.

[0052] <Molding method using injection molding machine 1> Next, a resin molding method using this injection molding machine 1 will be described with reference to the flowchart of FIG.

[0053] First, the resin flow path 22 is filled with the resin material 6 (S.1). The resin material 6 is filled by supplying the resin material 6 from the dispenser 5 into the resin flow path 22. At this time, the valve pin 23 is retracted and the gate 21 is in an open state. When filling of the resin flow path 22 with the resin material 6 is completed, the valve pin 23 is moved forward and the gate 21 is temporarily closed (S.2). At this time, the diaphragm 24 is in the state shown in FIG. 5(b) and is separated from the opposing surface 16a. The diaphragm 24 is deformed and the opening hole 24a is moved downward (forward direction).

[0054] As the resin molding starts, the valve pin 23 is moved backward to open the gate 21 (S.3: Opening step). At this time, the diaphragm 24 is in the state shown in Fig. 5(a) and supported by the opposing surface 16a. The diaphragm 24 is deformed and the opening hole 24a moves upward (backward).

[0055] Thereafter, the dispenser 5 applies a positive pressure to the resin material 6 in the resin flow path 22, and injects the resin material 6 from the gate 21 toward the cavity 10 (S.4: injection step). When the injection of a predetermined amount of the resin material 6 is completed, the dispenser 5 stops applying the positive pressure.

[0056] Thereafter, the dispenser 5 applies negative pressure to the resin material 6 in the resin flow path 22, and partially sucks the resin material 6 in the resin flow path 22 (depressurization step: S.5). Then, the positive pressure in the resin flow path 22 is removed, and after the pressure is approximately atmospheric pressure or a slight negative pressure state (i.e., after the depressurization step), the valve pin 23 is moved forward to close the gate 21 (S.6: closing step). At this time, the diaphragm 24 is in the state shown in FIG. 5(b) and is separated from the opposing surface 16a. The diaphragm 24 is deformed, and the opening hole 24a moves downward (forward direction).

[0057] In addition, in this closing step, the dispenser 5 may apply negative pressure to the resin material 6 in the resin flow path 22 while moving the valve pin 23 forward to close the gate 21. That is, the closing step may be performed together with (almost simultaneously with) the depressurization step. In this way, the degree of reduction in the volume of the resin flow path 22 caused by the diaphragm 24 and the degree of reduction in the volume of the resin material 6 in the resin flow path 22 caused by partial suction of the resin material 6 can be adjusted in a well-balanced manner, which is more preferable.

[0058] When resin molding is to be repeated, the process returns to S.3 after S.6 and repeats steps S.3 to S.6. Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications and changes are possible within the scope of the gist of the present invention. For example, the present invention includes the following gist.

[0059] (Objective 1) an injection port for injecting a resin material into the mold; a resin flow path that guides the resin material to the injection port; a valve pin extending in a generally axial shape, capable of moving forward or backward along a direction in which the axis extends, and disposed midway through the resin flow path so as to penetrate an inside and an outside of the resin flow path, the injection port is disposed near a first end of the resin flow path that is closer to the inside of the mold, a through hole is formed in the resin flow path, through which the valve pin passes from the inside of the flow path to the outside of the flow path; the valve pin realizes a closed state in which the valve pin closes the injection port from inside the resin flow path by forward movement, and an open state in which the valve pin opens the injection port to allow the resin material to be injected from the injection port by backward movement, a sealing member is disposed near the through hole to seal the through hole and isolate the inside and outside of the resin flow path; At least a portion of the sealing member is fixed to the valve pin and is deformable in accordance with back and forth movement of the valve pin.

[0060] (Objective 2) The sealing member may further include a support member that supports the sealing member from outside the resin flow path in order to restrict deformation of the sealing member toward the outside of the resin flow path in the open state.

[0061] (Objective 3) The sealing member may be made of an elastic material containing rubber or silicon, or may be made of a metallic material.

[0062] (Objective 4) The method further includes a material supplying means for supplying the resin material into the resin flow path from a second end of the resin flow path that is farther from the inside of the mold, The material supplying means may be capable of applying a positive pressure and a negative pressure to the resin material in the resin flow path.

[0063] (Objective 5) A molding method using the above molding apparatus, an opening step of moving the valve pin backward from the closed state in which the resin material is filled in the resin flow path to the open state; an injection step of applying a positive pressure to the resin material in the resin flow path after the opening step to inject the resin material into the mold; a depressurization step of applying a negative pressure to the resin material in the resin flow path after the injection step; and a closing step of moving the valve pin forward to achieve the closed state, after or together with the depressurizing step. [Explanation of symbols]

[0064] M1: Driving means X: Arrow 1: Injection molding machine (molding equipment) 1a: Nozzle 1b: Bush 2: Press equipment 3: Fixed mold (mold with built-in hot runner) 4: Movable mold 5: Dispenser (material supply means) 6: Resin material 10:Void (inside the mold) 11: Mounting plate 11a: Fitting recess 12: Manifold 13: Back plate 14: Cavity plate 15: Fastening member 16: Support member 16a: Opposite surface 21: Gate (exit) 22: Resin flow path 22a: First end (end close to the inside of the mold) 22b: Second end (end farther from the inside of the mold) 22c: Through hole 23: Valve pin 23a:Tip 23b: Rear end 23c: Stepped section 24: Diaphragm (sealing material) 24a: Opening hole 24b:Outer edge 25: Nut 26: Washer

Claims

1. an injection port for injecting a resin material into the mold; a resin flow path that guides the resin material to the injection port; a valve pin extending in a generally axial shape, capable of moving forward or backward along a direction in which the axis extends, and disposed midway through the resin flow path so as to penetrate an inside and an outside of the resin flow path, the injection port is disposed near a first end of the resin flow path that is closer to an inside of the mold, a through hole is formed in the resin flow path, through which the valve pin passes from the inside of the flow path to the outside of the flow path; the valve pin realizes a closed state in which the valve pin closes the injection port from inside the resin flow path by forward movement, and an open state in which the valve pin opens the injection port by backward movement to enable injection of the resin material from the injection port, a sealing member is disposed near the through hole to seal the through hole and isolate the inside and outside of the resin flow path; At least a portion of the sealing member is fixed to the valve pin and is deformable in accordance with back and forth movement of the valve pin.

2. The molding apparatus according to claim 1 , further comprising a support member that supports the sealing member from outside the resin flow path to restrict deformation of the sealing member outward from the resin flow path in the open state.

3. The molding apparatus according to claim 1 , wherein the sealing member is made of an elastic material containing rubber or silicon, or is made of a metal material.

4. The method further includes a material supplying means for supplying the resin material into the resin flow path from a second end of the resin flow path that is farther from the inside of the mold, 4. The molding apparatus according to claim 1, wherein the material supplying means is capable of applying a positive pressure and a negative pressure to the resin material in the resin flow path.

5. A molding method using the molding apparatus according to any one of claims 1 to 3, an opening step of moving the valve pin backward from the closed state in which the resin flow path is filled with the resin material to the open state; an injection step of applying a positive pressure to the resin material in the resin flow path after the opening step to inject the resin material into the mold; a depressurization step of applying a negative pressure to the resin material in the resin flow path after the injection step; and a closing step of moving the valve pin forward to achieve the closed state, after or together with the depressurizing step.

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