JP4589826B2 - Method for molding synthetic resin injection molded product and injection mold apparatus - Google Patents

Description

  The present invention relates to a method for molding a synthetic resin molded product in which a secondary injection molded portion is integrated with a primary injection molded portion, and an injection mold apparatus.

  In the synthetic resin injection molding, when the resin is injected from the gate 20 into the cavity portion 21, the injected resin usually flows concentrically around the gate 20 as shown in FIG. The final arrival point A of the resin is the point B farthest from the gate 20 in the cavity portion 21 and is usually designed so that the outer periphery of the synthetic resin injection molded product to be molded becomes the final arrival point A of the resin. The outer periphery of the synthetic resin injection molded product is usually a split surface of the mold. For this reason, the gas in the cavity portion 21 is pushed by the injected resin, and the split surface of the mold at the final arrival point of the resin. From the outside. For this reason, a gas venting mechanism is not necessary in general injection molding.

  Patent Document 1 discloses that a gas venting mechanism is provided in injection molding. In this patent document 1, a first resin is provided from a first gate provided in a mold, and a second resin having a color different from that of the first resin is provided in a cavity portion from a second gate. The two-color container is molded at the same time, and in this case, a gas venting mechanism is provided at the junction between the first resin and the second resin of the mold to vent the gas generated during molding. Like to do.

  As described above, in the conventional injection molding, the gas venting mechanism is not provided, or when the gas venting mechanism is provided, the gas venting is provided at the joining portion of the first resin and the second resin in the two-color molding. It is only known.

  By the way, in the process leading to the present invention, the present inventor overlaps and integrates the overlapping portions 3b on both sides of the secondary injection molding portion 2 with the overlapping surface 12 of the outer surface of the adjacent primary injection molding portion 1 located at a distance from each other. Further, the synthetic resin injection molded product 4 as shown in FIG. 6 in which the portion between the overlapping portions 3b on both sides of the secondary injection molded portion 2 becomes a non-overlapping portion 3a that does not overlap with the primary injection molded portion 1 is shown in FIG. It considered that it shape | molds using the injection mold apparatus 5 as shown in FIG.

  That is, as shown in FIG. 8, a plurality of primary injection molds for closing the injection mold device 5 comprising a plurality of mold parts 6 and advancing the slide core 7 to form a plurality of primary injection molding parts 1 are performed. As shown in FIG. 9, the first resin 10 is formed from the first gate 15 for primary injection molding into each of the plurality of primary injection molding cavities 8, as shown in FIG. A plurality of primary injection molding parts 1 are formed by injection by primary injection molding. Next, as shown in FIG. 10, the slide core 7 is moved backward to overlap the overlapping surface 12 of the adjacent primary injection molding parts 1. Secondary straddling the space surrounded by the part 6a1 of the mold part 6 located between the primary injection molding parts 1 adjacent to each other and the retracted slide core 7 between the end parts of the adjacent primary injection molding parts 1 Formed as injection molding cavity 13 and then As shown in FIG. 11, the secondary injection molding part 2 is formed by injecting the second resin 14 from the second gate 16 for secondary injection molding into the secondary injection molding cavity part 13 by secondary injection molding. At the same time, the overlapping portions 3b on both sides of the secondary injection molded portion 2 are overlapped and integrated with the respective overlapping surfaces 12 of the adjacent primary injection molded portions 1, whereby a synthetic resin injection molded product 4 as shown in FIG. Can be molded.

  Here, the second gate 16 for secondary injection molding is formed between the primary injection molding parts 1 in the part 6a1 of the mold part 6 located between the adjacent primary injection molding parts 1 as shown in FIG. A plurality of them are provided at a substantially center in the width direction and in a direction perpendicular to the width direction.

  Then, the second resin 14 injected from the second gate 16 shown in FIG. 12 first flows concentrically from the plurality of second gates 16 as shown by A1 and A2 in FIG. However, the second resin 14 injected from the second gate 16 flows along the exposed surface 12 of the primary injection molded part 1 and along the surfaces of the mold part 6 (6a1) and the slide core 7. Since the temperature of the exposed surface 12 of the primary injection molding part 1 is higher than the surface temperature of the mold part 6 and the slide core 7, the exposed surface 12 is shown as A3 and A4 in FIG. The second resin 14 that flows along the mold flows faster than the second resin 14 that flows along the mold part 6 (6a1) and the slide core 7, and is therefore the farthest point from the adjacent second gate 16. Shown in FIG. Since it flows along the exposed surface 12 of the primary injection molding part 1 to the place, it flows quickly. On the other hand, to the place shown in FIG. 5C, which is in the middle between the second gates 16, along the mold part 6 (6a1). It flows slowly because it flows. In this way, the portion that is farthest from the adjacent second gate 16, the portion indicated by B in FIG. 12, flows fast because it flows along the exposed surface 12 of the primary injection molding portion 1, while the second gate 16. Since it flows along the mold part 6, it flows slowly to the position indicated by C in FIG. For this reason, although the location indicated by B in FIG. 12 is farthest from the second gate 16, the second resin 10 is faster than the location indicated by C in FIG. 12 is the final arrival point a where the second resin arrives the latest. Therefore, the gas in the secondary molding cavity portion 13 gathers and escapes at a location indicated by an intermediate c between the second gates 16 that are the final arrival locations a without being vented at the split surface of the mold portion 6. There is a problem that gas burns and short shots occur.

Further, even in the injection molding as shown in the above-mentioned Patent Document 1, when the second resin is injected, the second resin that flows along the exposed surface of the high-temperature primary injection molded portion that has already been injection molded, It is not a technique for solving the problem of degassing in the case where the flow speed of the second resin flowing through the mold part whose surface temperature is lower than that of the exposed surface of the primary injection molding part is different.
JP-A-6-23793

  The present invention was invented in view of the above-described conventional problems, and the overlapping portions on both sides of the secondary injection molding portion were overlapped and integrated with the exposed surface of the outer surface of the primary injection molding portion adjacent to each other at a distance. To provide a molding method and an injection mold apparatus for a synthetic resin injection molded product capable of preventing gas burnout and short shot by reliably extracting gas in a cavity for secondary injection molding when molding an injection molded product. Is an issue.

  In order to solve the above-described problems, the method for molding a synthetic resin injection molded product according to the present invention is such that both sides of the secondary injection molded part 2 are placed on the overlapping surface 12 of the outer surface of the adjacent primary injection molded part 1 located at a distance from each other. The synthetic resin injection molded product 4 in which the overlapping portions 3b of the secondary injection molding portion 2 are overlapped and integrated into a non-overlapping portion 3a that does not overlap with the primary injection molding portion 1 is injected. A molding method for molding with a molding die device 5, which closes an injection molding die device 5 composed of a plurality of mold parts 6 and advances a slide core 7 to form a plurality of primary injection molding parts 1. A plurality of primary injection molding cavities 8 to be formed are formed at a distance from each other, and a first resin 10 is injected into the plurality of primary injection molding cavities 8 by primary injection molding to thereby form a plurality of primary injection molding parts. Mold 1 and then slide A with the overlapping surface 12 of the primary injection molding part 1 adjacent by retreating the door 7, the part of the mold part 6 located between the primary injection molding parts 1 adjacent to each other at a distance, and the slide core 7 retracted The enclosed space is formed as a secondary injection molding cavity 13 straddling between the ends of the adjacent primary injection molding parts 1, and then the second resin 14 is secondarily applied to the secondary injection molding cavity 13. The secondary injection molding part 2 is formed by injection by injection molding, and the overlapping parts 3b on both sides of the secondary injection molding part 2 are overlapped and integrated with the overlapping surfaces 12 of the adjacent primary injection molding parts 1 respectively. Thus, a plurality of gates 16 for secondary injection molding are provided in a direction substantially perpendicular to the width direction at the approximate center in the width direction of the portion of the mold part 6 positioned between the primary injection molding parts 1 adjacent to each other at a distance. Two pieces are provided and the gates 16 for secondary injection molding adjacent to each other at a distance are connected. A degassing part 9 is provided at a part of the mold part 6 or a part of the slide core 7 corresponding to a substantially intermediate position of the above, and a gas generated during secondary injection molding is extracted from the degassing part 9. Is.

  By such a method, after the first resin 10 is injection-molded by primary injection molding into a plurality of primary injection molding cavities 8, the slide core 7 is retracted and the overlapping surface 12 of the adjacent primary injection-molding part 1 Secondary injection straddling between the end portions of the adjacent primary injection molding part 1 surrounded by the part of the mold part 6 located between the primary injection molding parts 1 adjacent to each other at a distance and the retracted slide core 7 A molding cavity portion 13 is formed, and then a second resin 14 is injected from a plurality of secondary injection molding gates 16 into the secondary injection molding cavity portion 13 to mold a synthetic resin injection molded product 4. In this case, the flow rate of the second resin 14 flowing to the middle part between the adjacent gates 16 for secondary injection molding is slow, and the second resin 14 reaches the slowest part in this part (the part where there is no split surface). Despite doing, from the gas vent 9 It is possible to prevent the gas burning and short shot disconnect the really gas.

  In the injection mold apparatus of the present invention, the mold apparatus 5 is composed of a plurality of mold parts 6, and a forward and backward slide core 7 provided on the mold part 6 and a first resin 10 are injected. A first gate 15 for injecting, a second gate 16 for injecting the second resin 14, and a gas vent portion 9. The plurality of mold portions 6 are closed and the slide core 7 is closed. , The plurality of primary injection molding cavities 8 are formed such that the ends of the adjacent primary injection molding cavities are located at a distance from each other, and the plurality of mold parts 6 are molded. By closing and sliding the slide core 7 backward, the primary surface adjacent to the overlapping surface 12 exposed at least at the end of the outer surface of the primary injection molded portion 1 formed in the primary injection molding cavity portion 8 is spaced apart. The part of the mold part 6 located between the injection molding parts 1 and retreat A secondary injection molding cavity formed as a secondary injection molding cavity 13 straddling a space surrounded by the slide core 7 between the ends of adjacent primary injection molding parts 1 and projected from the moving direction of the slide core 7 The overlapping surfaces 12 of the adjacent primary injection molding portions 1 are respectively located on both sides of the projection surface of the portion 13 and are adjacent to the intermediate portion of the projection surface of the secondary injection molding cavity portion 13 with the above-mentioned distance. The part of the mold part 6 located between the primary injection molding parts 1 is located, and the second gate 16 is substantially in the width direction of the part of the mold part 6 located between the adjacent primary injection molding parts 1. Provided in the center and in a direction perpendicular to the width direction, at the part of the mold part 6 or the part of the slide core 7 corresponding to the substantially middle position of the line connecting the second gates 16 adjacent to each other at a distance. It is characterized by providing a gas vent 9 It is intended.

  As described above, a plurality of gas venting portions 9 are provided in a portion of the mold portion 6 or a portion of the slide core 7 corresponding to a substantially middle position of the line connecting the second gates 16 adjacent to each other with a distance. When the second resin 14 is injected from the secondary injection molding gate 16 to form the synthetic resin injection molded product 4, the second resin flows to an intermediate portion between the adjacent secondary injection molding gates 16. Despite the slowest flow rate of the resin 14 and the second resin 14 reaching the slowest part (the part where there is no split surface), the gas venting part 9 is surely vented to perform gas burning or short shots. The injection mold apparatus 5 that can be prevented can be provided.

  In the present invention, when molding an injection molded product in which the overlapping portions on both sides of the secondary injection molding portion are overlapped and integrated on the exposed surface of the outer surface of the primary injection molding portion adjacent to each other at a distance, the second By providing a gas vent at the mold part or slide core part corresponding to approximately the middle position of the line connecting the two gates, the gas in the cavity for secondary injection molding is surely vented. Gas burns and short shots can be prevented.

  Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

  As shown in FIG. 6, the synthetic resin molded product 4 molded by the synthetic resin injection molded product molding method and the injection mold apparatus of the present invention has at least one of the outer surfaces of the primary injection molded portion 1. A part of the secondary injection molding part 2 (overlapping part 3b) is overlapped and integrated at the end, and the non-overlapping part 3a of the secondary injection molding part 2 projects beyond the end of the primary injection molding part 1. is there.

  In the embodiment shown in FIG. 6, an example in which a plurality of primary injection molded parts 1 are integrally connected by a secondary injection molded part 2 is shown. In this example, for example, PP (polypropylene), PE (polyethylene), HDPE (Primary injection molded part 1 is formed with a first resin 10 made of a hard resin such as (high density polyethylene), PC (polycarbonate), PVC (vinyl chloride resin), ABS resin, etc., for example, TPE (elastomer), LDPE Non-overlapping part of the secondary injection molded part 2 made of soft resin by forming the secondary injection molded part 2 with the second resin 14 made of soft resin such as (low density polyethylene) or EVA (ethylene vinyl acetate copolymer) An example in which 3a constitutes a hinge portion is shown. That is, in the present embodiment, the synthetic resin injection in which the primary injection molding parts 1 made of the hard synthetic resin adjacent to each other at a distance are connected to each other by the secondary injection molding part 2 made of the soft synthetic resin so as to be foldable (or rotatable). An example of the molded product 4 is shown.

  FIG. 1 shows an example of an injection mold apparatus 5 of the present invention for molding the synthetic resin molded product 4 shown in FIG.

  The mold apparatus 5 for injection molding injects the slide core 7 which can be moved forward and backward provided in the mold part 6, the first gate 15 for injecting the first resin 10, and the second resin 14. And a second gate 16 for the purpose.

  The mold part 6 includes a fixed mold part 6a and a movable mold part 6b. A recess 18 is provided on a surface of the movable mold part 6b facing the fixed mold part 6a. The slide core 7 is housed in such a manner that it can be moved forward and backward (in FIG. 1, the arrow X indicates the forward direction and the arrow Y indicates the backward direction).

  In the present invention, the movable mold part 6b is movable in the lateral direction (horizontal direction) or the vertical direction (vertical direction) with respect to the fixed mold part 6a, and by moving the movable mold part 6b. The mold is closed and the mold is opened. Moreover, the slide core 7 is movable in the same direction as the movable direction of the movable mold part 6b with respect to the movable mold part 6b.

  The fixed mold part 6a and the movable mold part 6b are closed and the slide core 7 is advanced, and the fixed mold part 6a, the movable mold part 6b, and the advanced slide core 7 are surrounded. This space is formed as a primary injection molding cavity 8. A plurality of the primary injection molding cavities 8 are formed, and the ends of the adjacent primary injection molding cavities 8 are separated by a distance. The slide core 7 extends between the end portions of the adjacent primary injection molding cavities 8, and the center portion of the front surface of the slide core 7 is adjacent to each of the primary injection molding cavities adjacent to the fixed mold portion 6 a. The both sides of the front surface of the slide core 7 are opposed to the portion 6a1 between the eight end portions, and constitute an inner surface on one side of the end portion of the primary injection molding cavity portion 8 adjacent thereto.

  The plurality of primary molding cavities 8 are formed by providing a plurality of cavity forming recesses 17 on one or both of the opposing surfaces of the fixed mold part 6a to the movable mold part 6b. In the embodiment of the accompanying drawings, an example is shown in which a plurality of cavity forming recesses 17 are formed in the fixed mold part 6a.

  Further, only the slide core 7 is retracted in a state where the fixed mold part 6a and the movable mold part 6b are closed, so that the primary injection molded parts 1 molded in the adjacent primary injection molding cavity parts 8 respectively. One of the outer surfaces of each of the outer surfaces is exposed, and the overlapping surface 12 and the mold are exposed surfaces of the primary injection molding portion 1 respectively molded in the adjacent primary injection molding cavity portion 8. A space to be a secondary injection molding cavity 13 surrounded by the part 6 and the slide core 7 is formed.

  Each of the first gate 15 and the second gate 16 is provided in the fixed mold part 6a, and a plurality of the first gates 15 are provided so as to correspond to one or a plurality of primary injection molding cavities 8 respectively. Thus, one or more first gates 15 that are a set open to each primary injection molding cavity 8 corresponding to each set.

  The second gate 16 is substantially at the center in the width direction of the mold surface of the portion 6a1 between the end portions of the adjacent primary injection molding cavities 8 of the fixed mold portion 6a and is orthogonal to the width direction. (The width direction is the width direction in the same direction as the adjacent directions of the primary molding cavities 8), and the mold part 6 is closed. At the same time, the front end surface of the slide core 7 is brought into contact with the second gate 16 and closed in a state where the slide core 7 is moved forward, and the mold portion 6 is closed and the slide core 7 is moved backward. The second gate 16 is configured to open to the secondary injection molding cavity 13 in a state where the secondary injection molding cavity 13 is formed.

  Also, each primary injection molding cavity portion 8 adjacent to the fixed mold portion 6a in the portion 6a1 between the end portions of each adjacent primary injection molding cavity portion 8 of the fixed mold portion 6a or the slide core 7 portion. Gas at a position corresponding to a substantially middle position of a line connecting the second gates 16 adjacent to each other with a distance provided at a substantially central position in the width direction of the portion 6a1 between the end portions of the first gate gate and a direction perpendicular to the width direction. A punching portion 9 is provided.

  For example, as shown in FIG. 1, the gas vent 9 is provided with a through hole 9a in the slide core 7 or the fixed mold part 6a (slide core 7 in FIG. 1) and a pin 9b is inserted into the through hole 9a. A gas is allowed to pass between the inner peripheral surface of 9a and the outer peripheral surface of the pin 9b, but a very small gap that cannot pass through the resin is formed. The gas in the secondary injection molding cavity 8 is the above gas. The gas is vented from a very small gap between the inner peripheral surface of the through hole 9a and the outer peripheral surface of the pin 9b constituting the extraction portion 9.

  The synthetic resin injection molded product 4 is molded using the injection molding die device 5 as described above as follows.

  First, as shown in FIG. 1, a plurality of mold parts 6 are closed and the slide core 7 is advanced to form a primary injection molding cavity 8, and the primary injection molding cavity 8 is shown in FIG. 2. Thus, the primary injection process which inject | pours the 1st resin 10 from the 1st gate 15 by primary injection molding, and shape | molds the primary injection molding part 1 is implemented.

  By this primary injection molding, the primary injection molding part 1 is molded in the cavity part 8 for primary injection molding.

  In this case, the first resin 10 injected from the first gate 15 into the primary injection molding cavity 8 spreads concentrically around the first gate 15 and enters the primary injection molding cavity 8. Since it is filled, the split surface of the mold part 6 (each split surface of the fixed mold part 6a, the movable mold part 6b, and the slide core 7) is located in a place farthest from the first gate 15. The split surface portion of the mold part 6 is the final arrival point of the first resin 10, and the gas venting during the primary injection molding is performed from the split surface.

  Next, as shown in FIG. 3, the secondary injection molding cavity 13 is formed by retracting the slide core 7 with the plurality of mold parts 6 being closed.

  Next, the second resin 14 is injected by secondary injection molding from the plurality of second gates 16 into the secondary injection molding cavity 13 formed as described above, and the secondary injection molding as shown in FIG. The overlapping part 3b of the both ends of the secondary injection molding part 2 overlaps and integrates with the overlapping surface 12 of the outer surface edge part of the one side of the primary injection molding part 1 which adjoins and forms the injection molding part 2 through a distance.

  As described above, the second resin 14 injected into the secondary injection molding cavity 13 from the plurality of second gates 16 is initially a plurality of second resins as shown in A1 and A2 of FIG. The second resin 14 injected from the second gate 16 flows along the exposed surface 12 of the primary injection molding part 1 and the mold part 6 (6a1). ) And those that flow along the surface of the slide core 7, and the temperature of the exposed surface 12 of the primary injection molding part 1 is higher than the surface temperature of the mold part 6 and the slide core 7. As shown by A3 and A4, the second resin 14 that flows along the exposed surface 12 flows faster than the second resin 14 that flows along the mold part 6 (6a1) and the slide core 7, and therefore the adjacent second resin 14 flows. Farthest from second gate 16 5 to the place shown in FIG. 5B because it flows along the exposed surface 12 of the primary injection molding part 1, it flows fast, while the place shown in FIG. Since it flows along the mold part 6, it flows slowly. In this way, the portion that is farthest from the adjacent second gate 16, the portion indicated by B in FIG. 5, flows along the exposed surface 12 of the primary injection molding portion 1, and thus flows fast, while the second gate 16. Since it flows along the mold part 6 (6a1), it flows slowly to the position shown in FIG. For this reason, although the location indicated by B in FIG. 5 is farthest from the second gate 16, the second resin 10 is faster than the location indicated by C in FIG. 5 is the final arrival point a where the second resin arrives the latest, but the mold part 6 (6a1) corresponding to the intermediate part between the second gates 16 or Since the gas vent 9 is provided in the slide core 7, the gas generated in the final filling portion can be surely vented from the gas vent 9, and it is possible to prevent gas burning and short shots from occurring. A synthetic resin molded product 4 having an appearance as designed and excellent in aesthetics can be molded.

  After the secondary injection molding is performed as described above, a mold release step is performed in which the mold apparatus 5 for injection molding is opened and the synthetic resin injection molded product 4 is taken out.

  From these series of mold closings, a series of processes such as primary injection molding, secondary injection molding, and mold release process are executed under the control of a control unit (not shown).

  In addition, as shown in FIG. 6, in the case where the overlapping portions 3b on both sides of the secondary injection molding portion 2 are laminated and integrated at the ends of the primary injection molding portions 1 adjacent to each other at a distance, the primary injection molding portion 1 is When the first resin 10 for forming is a hard resin and the second resin 143 for forming the secondary injection molded part 2 is a soft resin, the non-overlapping part of the intermediate part of the secondary injection molded part 2 3a (that is, the non-overlapping portion 3a at the intermediate portion of the secondary injection molding portion 2 is a portion protruding from the end portions of both primary injection molding portions 1) is a hinge portion, and is made of the hard first resin 10. The primary injection molded parts 1 can be integrally connected to each other by a hinge part made of the soft second resin 14 so as to be bent.

The injection molding die apparatus of this invention is shown, (a) is front sectional drawing of a mold closed state, (b) is side sectional drawing. It is front sectional drawing of the injection mold apparatus of the state which filled the 1st resin by primary injection molding to the primary injection molding cavity part same as the above, and formed the primary injection molding part, (b) Front side sectional drawing It is. It is front sectional drawing of the injection mold apparatus of the stage which formed the cavity part for secondary injection molding same as the above, (b) is side sectional drawing. It is front sectional drawing of the injection mold apparatus of the stage which filled the 2nd resin by secondary injection molding in the secondary injection molding cavity part same as the above, and formed the secondary injection molding part, (b) is side view It is sectional drawing. It is explanatory drawing of the flow of the 2nd resin at the time of injecting 2nd resin from the 2nd gate to the cavity part for secondary injection molding same as the above, and degassing. An example of the synthetic resin injection-molded product molded by the same as above is shown, (a) is a perspective view, and (b) is a cross-sectional view. It is explanatory drawing of the flow of the resin inject | emitted from the gate of the prior art example, and degassing. It is sectional drawing of the mold closing state which shows the injection molding die apparatus of a comparative example. It is sectional drawing of the injection mold apparatus of the state which filled the 1st resin by primary injection molding to the primary injection molding cavity part same as the above, and formed the primary injection molding part. It is sectional drawing of the injection mold apparatus of the stage which formed the cavity part for secondary injection molding same as the above. It is sectional drawing of the injection mold apparatus of the stage which filled the 2nd resin by secondary injection molding in the secondary injection molding cavity part same as the above, and formed the secondary injection molding part. It is explanatory drawing explaining that the gas accumulates between the flow of the 2nd resin at the time of injecting 2nd resin from the 2nd gate to the cavity part for secondary injection molding same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Primary injection molding part 2 Secondary injection molding part 3a Non-overlapping part 3b Overlapping part 4 Synthetic resin injection molded article 5 Injection mold apparatus 6 Mold part 7 Slide core 8 Cavity part for primary injection molding 9 Gas vent part 10 1st One resin 12 Overlapping surface 13 Secondary injection molding cavity portion 14 Second resin 15 First gate 16 Second gate

Claims (2)

The overlapping portions on both sides of the secondary injection molding portion are integrated with the overlapping surfaces of the outer surfaces of the adjacent primary injection molding portions located at a distance from each other, and the portions between the overlapping portions on both sides of the secondary injection molding portion are integrated. A molding method for molding a synthetic resin injection molded product that has become a non-overlapping part that does not overlap with a primary injection molding part with an injection mold device,
A plurality of primary injection molding cavities for forming a plurality of primary injection molding parts by forming a plurality of primary injection molding parts by closing a mold of an injection molding device comprising a plurality of mold parts and advancing a slide core, are formed at a distance,
The first resin is injected into a plurality of primary injection molding cavities by primary injection molding to form a plurality of primary injection molding parts, and then the slide core is moved backward to overlap the adjacent primary injection molding parts. And secondary injection molding straddling the space surrounded by the part of the mold part located between the primary injection molding parts adjacent to each other at a distance and the end of the primary injection molding part adjacent to each other by the retracted slide core Next, the second resin is injected into the secondary injection molding cavity by secondary injection molding to form a secondary injection molding portion and overlapping portions on both sides of the secondary injection molding portion Are overlapped and integrated with each overlapping surface of the adjacent primary injection molding parts,
A plurality of gates for secondary injection molding are provided in the direction substantially perpendicular to the width direction of the portion of the mold part located between the primary injection molding parts adjacent to each other at a distance, and the distance is set. A gas vent part is provided in the part of the mold part or the part of the slide core corresponding to a substantially intermediate position of a line connecting the gates for secondary injection molding adjacent to each other, and the gas generated during the secondary injection molding is described above. A method for molding a synthetic resin injection-molded product, wherein the method vents from a gas vent. An injection mold apparatus for molding the synthetic resin injection-molded product according to claim 1, wherein the mold apparatus comprises a plurality of mold parts, and a slide core that is provided on the mold part and is movable forward and backward. A first gate for injecting the first resin, a second gate for injecting the second resin, and a gas vent,
By closing the plurality of mold parts and moving the slide core forward, a plurality of primary injection molding cavities are positioned such that the ends of adjacent primary injection molding cavities are spaced apart from each other. Forming,
By closing the plurality of mold parts and retracting the slide core, a distance from the overlapping surface where at least the end part of the outer surface of the primary injection molded part formed in the primary injection molding cavity part is exposed is separated. Formed as a cavity part for secondary injection molding straddling the end part of the adjacent primary injection molding part in the space surrounded by the part of the mold part located between the adjacent primary injection molding parts and the retracted slide core The overlapping surfaces of the adjacent primary injection molding parts are respectively located on both sides of the projection surface of the secondary injection molding cavity part projected from the moving direction of the slide core, and the projection surface of the secondary injection molding cavity part The part of the mold part located between the primary injection molding parts that are adjacent to each other with the above distance in the middle part of
A plurality of the second gates are provided in the direction substantially perpendicular to the width direction of the part of the mold part located between the adjacent primary injection molding parts and in a direction orthogonal to the width direction, and are adjacent to each other at a distance. An injection mold apparatus comprising a degassing section at a position of the mold section or a slide core corresponding to a substantially middle position of a line connecting two gates.

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