Injection molding method for resin molded products

Abstract

To enhance positional accuracy of an insert member in a resin molding.SOLUTION: A positioning pin 105 having a columnar part 105b is provided on a movable die 103 so as to project from a movable die side second molding surface 103b of the movable die 103, a positioning hole 19a is formed in an insert member 15, the insert member 15 is mounted on the movable die 103, the positioning pin 105 is made to project from the movable die side second molding surface 103b of the movable die 103 and inserted into the positioning hole 19a of the insert member 15, and thereby the columnar part 105b of the positioning pin 105 is fit into the positioning hole 19a of the insert member 15, and injection of the resin into a cavity C is started in a preparation state where a fixed die 101 and the movable die 103 are clamped.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an injection molding method and an injection molding die for molding a resin molded product with an insert member inserted therein by injecting and filling a cavity formed between a first molding die, a second molding die and an insert member. [Background technology]

[0002] Patent Document 1 discloses an injection molding method for molding a resin molded product with an insert member inserted therein by injecting and filling a cavity formed between a first mold, a second mold, and an insert member. In this injection molding method, a support member is provided on the first mold so as to be able to protrude from the molding surface of the first mold, and injection of resin into the cavity is started with the insert member placed on the support member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-72099 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, when the injection of resin into the cavity begins, the movement of the insert member in a direction perpendicular to the protruding direction of the support member is not restricted, so the injection pressure of the resin may cause the insert member to move in a direction perpendicular to the protruding direction of the support member, which may result in a deterioration in the positional accuracy of the insert member in the resin molded product.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to improve the positional accuracy of an insert member in a resin molded product. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention is characterized in that a positioning pin provided on a first molding die can be inserted into a positioning hole of an insert member.

[0007] Specifically, the first to sixth inventions are directed to an injection molding method for molding a resin molded product into which an insert member is inserted by injecting and filling a cavity formed between a first molding die and a second molding die and an insert member, and provide the following solutions.

[0008] That is, in the first invention, a positioning pin having a columnar portion is provided in the first mold so as to be protrudible from a molding surface of the first mold, a positioning hole is formed in the insert member, and the insert member is placed in either the first mold or the second mold, a peripheral portion of the positioning hole of the insert member is opposed to a molding surface of the first mold with a gap therebetween; The positioning pin is protruded from the molding surface of the first molding die and inserted into the positioning hole of the insert member, thereby fitting the columnar portion of the positioning pin into the positioning hole of the insert member, and in the preparatory state in which the first molding die and the second molding die are clamped, injection of resin into the cavity is started.

[0009] The second invention is characterized in that, in the injection molding method for a resin molded product relating to the first invention, a tapered portion which gradually becomes narrower in the protruding direction is formed continuously with the columnar portion at the protruding side end of the positioning pin.

[0010] A third invention is characterized in that, in the injection molding method for a resin molded product relating to the second invention, in the preparatory state, there is a gap between the tapered portion of the positioning pin and the molding surface of the second mold.

[0011] A fourth invention is a method for injection molding a resin molded product according to any one of the first to third inventions, characterized in that the positioning pin is arranged to be able to move back and forth in the protruding direction and the counter-protruding direction, and between the start and end of injection of resin into the cavity, the positioning pin is retracted from a position in the preparatory state to a predetermined retracted position in the counter-protruding direction, and the resin is also filled into the space formed by the retraction of the positioning pin.

[0012] The fifth invention is characterized in that, in the injection molding method for a resin molded product relating to the fourth invention, a tapered portion which gradually becomes narrower in the protruding direction is formed continuously with the columnar portion at the protruding side end of the positioning pin, and at the retracted position, the columnar portion of the positioning pin is released from the positioning hole of the insert member and the entire tapered portion is caused to protrude from the molding surface of the first mold.

[0013] A sixth invention is a method for injection molding a resin molded product according to any one of the first to fifth inventions, characterized in that the positioning pin is provided so as to be movable forward and backward in a protruding direction and a counter-protruding direction, a recess is formed in the resin molded product, and before the resin molded product is released from a position where the positioning pin engages with the recess of the resin molded product to prevent the release of the resin molded product, to a non-protruding position where the positioning pin does not protrude from the molding surface of the first mold, thereby enabling the resin molded product to be released from the mold. 。 Effect of the Invention

[0014] According to the first invention, when the injection of resin into the cavity begins, the positioning pin prevents the insert member from moving in a direction perpendicular to the protruding direction of the positioning pin due to the injection pressure of the resin, thereby improving the positioning accuracy of the insert member in the resin molded product.

[0015] According to the second invention, the positioning pin can be more easily inserted into the positioning hole of the insert member, compared to when the protruding end face of the positioning pin is a flat surface of the same size and shape as the opening of the positioning hole of the insert member.

[0016] According to the third invention, since the molding surface of the second mold is not damaged by the tapered portion of the positioning pin, it is possible to provide the molding surface of the second mold with irregularities and form a grain pattern on the surface of the resin molded product by the irregularities, thereby increasing the degree of freedom in designing the resin molded product.

[0017] According to the fourth aspect of the present invention, even if the protruding end of the positioning pin approaches the molding surface of the second mold in the preparation state, the space can be filled with resin to thicken the portion of the resin molded product corresponding to the positioning pin. This makes it possible to prevent sink marks, uneven gloss, and holes from occurring in the resin molded product due to the portion of the resin molded product corresponding to the positioning pin being too thin.

[0018] According to the fifth aspect of the invention, since the columnar portion of the positioning pin is released from the positioning hole of the insert member at the retreated position, the positioning hole of the insert member can be covered with resin.

[0019] Furthermore, compared to when the tapered portion of the positioning pin is recessed further than the molding surface of the first mold in the retracted position, no protrusions are formed by the resin filled in the space, reducing the amount of resin used and keeping material costs down.

[0020] According to the sixth aspect of the present invention, the position of the positioning pin at the end of the injection of the resin into the cavity can be set to a position that prevents the release of the resin molded product from the mold, thereby increasing the degree of freedom in the shape of the resin molded product. 。 [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is an exploded perspective view of a vehicle back door having an inner panel as a resin molded product injection-molded by the injection molding method according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 13 is a perspective view of the right insert member. [Figure 4]FIG. 2 is a molding process diagram showing a preparatory state in the injection molding method according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a molding process diagram showing a state in which a resin is injected and filled into a cavity in the injection molding method according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a molding process diagram showing a state immediately before an inner panel is released from a movable mold in the injection molding method according to the first embodiment of the present invention. [Figure 7] FIG. 11 is a perspective view of a plate-shaped member as a resin molded product injection-molded by an injection molding method according to a second embodiment of the present invention. [Figure 8] 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 5 is a view equivalent to FIG. 4 of the second embodiment. [Figure 10] FIG. 7 is a view equivalent to FIG. 5 of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] (Embodiment 1) FIG. 1 shows a vehicle back door 1 of the vertical opening / closing type for opening and closing a door opening provided at the rear end of the body of a hatchback vehicle.

[0024] The back door 1 includes an inner panel 3 as a resin molded product located on the inside of the vehicle, an outer panel 5 made of resin located on the outside of the vehicle, and a window panel (not shown).

[0025] The inner panel 3 has a substantially plate-shaped plate portion 7 facing the outer panel 5. An approximately rectangular window opening 9 extending in the vehicle width direction is formed in the upper half of the plate portion 7. An outer peripheral wall portion 11 rising toward the outer panel 5 side is provided in an annular shape around the entire circumference on the outer peripheral edge of the plate portion 7 of the inner panel 3. As shown in FIG. 2, a pair of conical recesses 11a that gradually narrow toward the non-opening side are formed at an interval in the vertical direction on the inner peripheral surface of the upper half of the outer peripheral wall portion 11 on both sides in the vehicle width direction. An opening side peripheral wall portion 13 rising toward the outer panel 5 side is provided in an annular shape around the entire circumference on the opening 9 side edge of the plate portion 7.

[0026] The upper half of the inner panel 3 has an insert member 15 made of steel, as shown in FIG. 3, integrally inserted into both ends in the vehicle width direction. The insert members 15 on both sides in the vehicle width direction have a symmetrical shape. The insert member 15 has a plate-shaped main plate portion 17 with a plate surface facing in the plate thickness direction of the plate portion 7 of the inner panel 3. The main plate portion 17 is formed in a substantially V-shape in a plan view by a first plate portion 17a extending along the upper edge of the opening 9, a second plate portion 17b extending from the outer end of the first plate portion 17a in the vehicle width direction toward the outer side in the vehicle width direction at an inclination downward, and a third plate portion 17c extending downward from the lower end (the outer end in the vehicle width direction) of the second plate portion 17b. A protruding plate portion 19 with a plate surface facing in the vehicle width direction is provided on the outer edge of the third plate portion 17c of the main plate portion 17 in the vehicle width direction toward the outer panel 5. A pair of positioning holes 19a having a circular cross section are formed vertically at a distance therebetween through the protruding plate portion 19. The outer end in the vehicle width direction of the third plate portion 17c of the main plate portion 17 of each insert member 15 and the entire protruding plate portion 19 are embedded in the outer peripheral wall portion 11 of the inner panel 3, and the positioning hole 19a of the protruding plate portion 19 is located at a position corresponding to the recess 11a of the outer peripheral wall portion 11. The surface of the main plate portion 17 facing the outer panel 5 is exposed to the outer panel 5 side, and the surface of the main plate portion 17 facing away from the outer panel 5 is in contact with the plate portion 7 of the inner panel 3.

[0027] 4 to 6 show a method for injection molding the inner panel 3 configured as described above, as a method for injection molding a resin molded product according to the first embodiment of the present invention.

[0028] For molding, an injection molding die 100 as shown in Figures 4 and 5 and the insert member 15 are prepared. The injection molding die 100 includes a fixed die 101 as a second molding die, and a movable die 103 as a first molding die.

[0029] The fixed mold 101 has a fixed mold first molding surface 101a which molds the surface of the plate portion 7 of the inner panel 3 on the side opposite to the outer panel 5, and a fixed mold second molding surface 101b which molds the outer peripheral surface of the outer peripheral wall portion 11. The fixed mold first molding surface 101a faces substantially vertically downward, while the fixed mold second molding surface 101b faces substantially horizontally.

[0030] The movable mold 103 has a movable mold-side first molding surface 103a which molds the surface of the plate portion of the inner panel 3 on the outer panel 5 side, a movable mold-side second molding surface 103b which molds the inner peripheral surface of the outer peripheral wall portion 11, and a movable mold-side third molding surface 103c which molds the end surface of the outer peripheral wall portion 11 (the end surface on the outer panel 5 side). The movable mold-side first molding surface 103a and the movable mold-side third molding surface 103c face substantially vertically upward. On the other hand, the movable mold-side second molding surface 103b faces substantially horizontally.

[0031] The movable mold 103 is provided with a positioning pin 105 that can protrude from the movable mold side second molding surface 103b, a spring 107 that urges the positioning pin 105 in the anti-protruding direction, and a drive device (not shown) that moves the positioning pin 105 forward and backward in the protruding direction and the anti-protruding direction. Therefore, the positioning pin 105 can be advanced and retreated in the protruding direction and the anti-protruding direction. A conical tapered portion 105a that gradually becomes thinner in the protruding direction is formed at the protruding side end of the positioning pin 105. A cylindrical columnar portion 105b is formed continuously with the tapered portion 105a at the anti-protruding side of the tapered portion 105a of the positioning pin 105.

[0032] Then, the movable die 103 is lowered to open the injection molding die 100, and the positioning pin 105 is retracted to a non-protruding position where it does not protrude from the movable die side second molding surface 103b of the movable die 103, and the insert member 15 is placed on the movable die side first molding surface 103a of the movable die 103. In this state, as shown in Fig. 4, the surface on the anti-protruding side of the protruding plate portion 19 of the main plate portion 17 of the insert member 15 abuts against the movable die side first molding surface 103a of the movable die 103, and the protruding plate portion 19 and the movable die side second molding surface 103b face each other with a gap therebetween. Then, the positioning pin 105 is advanced against the biasing force of the spring 107 by driving the driving device, so that it protrudes from the movable mold-side second molding surface 103b of the movable mold 103, and the tapered portion 105a of the positioning pin 105 is inserted into the positioning hole 19a of the insert member 15, and then the columnar portion 105b of the positioning pin 105 is fitted into the positioning hole 19a of the insert member 15. This allows the insert member 15 to be positioned in a direction perpendicular to the protruding direction of the positioning pin 105 relative to the movable mold 103. At this time, since the tapered portion 105a that gradually becomes thinner toward the protruding direction is provided at the protruding side end of the positioning pin 105, the positioning pin 105 can be easily inserted into the positioning hole 19a of the insert member 15 compared to when the protruding side end face of the positioning pin 105 is a flat surface of the same size and shape as the opening of the positioning hole 19a of the insert member 15.

[0033] Next, in a state where the insert member 15 is positioned relative to the movable die 103 as described above, the movable die 103 is raised and the injection molding die 100 is clamped, so that a cavity C is formed between the fixed die 101 and the movable die 103 and the insert member 15, as shown in FIG. 4. In this preparation state, the tip of the positioning pin 105, i.e., the tapered portion 105a, and the fixed die side second molding surface 101b of the fixed die 101 are spaced apart by a distance D. Then, in this preparation state, the injection of the resin R into the cavity C is started. At this time, with the columnar portion 105b of the positioning pin 105 fitted into the positioning hole 19a of the insert member 15, the insert member 15 is restricted from moving in a direction perpendicular to the protruding direction of the positioning pin 105, so that the positional accuracy of the insert member 15 in the inner panel 3 can be improved.

[0034] Thereafter, before the injection of the resin R into the cavity C is completed, the positioning pin 105 is retracted by the driving device from the position in the above-mentioned preparation state in the anti-projection direction to a predetermined retracted position, as shown in Fig. 5. At the retracted position, the positioning pin 105 causes the columnar portion 105b to be removed from the positioning hole 19a of the insert member 15, and causes the entire tapered portion 105a to be protruded from the movable-mold-side second molding surface 103b of the movable mold 103. The timing for retracting the positioning pin 105 to the retracted position is a timing at which the resin R has been injected into the cavity C to such an extent that the insert member 15 does not move in a direction perpendicular to the protruding direction of the positioning pin 105 even if the columnar portion 105b of the positioning pin 105 is removed from the positioning hole 19a of the insert member 15. Then, by continuing to inject resin R into cavity C, resin R is injected to fill the entire cavity C, including space S formed by the retraction of positioning pin 105, and injection of resin R into cavity C is terminated.

[0035] In this way, the resin R is also filled into the space S formed by the retreat of the positioning pin 105, so that the portion of the inner panel 3 corresponding to the positioning pin 105 can be made thicker even when the protruding end of the positioning pin 105 approaches the fixed-mold-side second molding surface 101b of the fixed mold 101 in the preparation state. This makes it possible to prevent the occurrence of sink marks, uneven gloss, and holes in the inner panel 3 due to the portion of the inner panel 3 corresponding to the positioning pin 105 being too thin.

[0036] Furthermore, since the columnar portion 105b of the positioning pin 105 is released from the positioning hole 19a of the insert member 15 at the retreated position, the positioning hole 19a of the insert member 15 can be covered with the resin R.

[0037] Furthermore, compared to when the tapered portion 105a of the positioning pin 105 is retracted further than the second molding surface 103b on the movable mold side of the movable mold 103 in the retracted position, no protrusions are formed by the resin R filled in the space S, and the amount of resin R used can be reduced, thereby keeping material costs down.

[0038] In this manner, with the positioning pin 105 retracted to the retracted position, the resin R hardens, and the inner panel 3 with the insert member 15 inserted therein is molded. At this time, the tapered portions 105a of the positioning pin 105 engage with recesses 11a formed on the inner peripheral surfaces of the outer peripheral wall portions 11 on both sides in the vehicle width direction of the inner panel 3, thereby preventing the inner panel 3 from being released from the mold. In other words, the recesses 11a of the inner panel 3 form an undercut portion that cannot be removed from the movable mold 103.

[0039] Thereafter, the movable mold 103 is lowered to open the mold, and as shown in FIG. 6, the positioning pin 105 is further retracted by the drive device to a non-protruding position where it does not protrude from the second molding surface 103b of the movable mold 103 on the movable mold side, thereby enabling the inner panel 3 to be released, and the inner panel 3 is removed upward from the movable mold 103 (in the direction indicated by the arrow X in FIG. 6).

[0040] In this way, since the positioning pin 105 is retracted to a non-protruding position before the inner panel 3 is released, the position of the positioning pin 105 at the end of injection of the resin R into the cavity C can be set to a position that prevents the inner panel 3 from being released, thereby increasing the freedom of shape of the inner panel 3.

[0041] Therefore, according to the first embodiment, in the preparation state, the tapered portion 105a of the positioning pin 105 does not come into contact with the fixed-mold-side second molding surface 101b of the fixed mold 101, and the fixed-mold-side second molding surface 101b of the fixed mold 101 is not damaged by the tapered portion 105a of the positioning pin 105, so that it is possible to provide irregularities on the fixed-mold-side second molding surface 101b and form a grain pattern on the surface of the inner panel 3 (the surface opposite the outer panel 5) using the irregularities. This increases the degree of freedom in designing the inner panel 3.

[0042] Furthermore, in order to prevent the insert member 15 from moving due to the injection pressure of the resin R, when the insert member 15 is sandwiched between the fixed die 101 and the movable die 103, it becomes necessary to provide an exposed area of ​​the insert member 15 due to contact with the fixed die 101 and the movable die 103 on both sides of the inner panel 3. In contrast, according to the first embodiment, since the insert member 15 is simply placed on the movable die 103 in a preparation state, it is sufficient to provide an exposed area of ​​the insert member 15 due to contact with the movable die 103 on only one side of the inner panel 3, and there is no need to provide an exposed area of ​​the insert member 15 on both sides of the inner panel 3, so that the freedom of design of the inner panel 3 can be increased.

[0043] In addition, since the exposed area of ​​the insert member 15 caused by contact with the movable mold 103 is provided on the non-exposed surface of the plate portion 7 of the inner panel 3 facing the outer panel 5, the appearance of the inner panel 3 can be improved compared to when it is provided on the exposed surface (design surface) of the inner panel 3.

[0044] (Embodiment 2) 7 and 8 show a plate-shaped member 21 as a rectangular plate-shaped resin molded product. The front surface (the lower surface in Figs. 7 and 8) of this plate-shaped member 21 is formed flat. On the other hand, on the back surface of the plate-shaped member 21, a pair of conical recesses 21a that gradually narrow toward the side opposite to the opening are formed at an interval in the longitudinal direction.

[0045] A rectangular iron insert member 23 is integrally inserted into the plate-like member 21. A bulging portion 23a is formed in the approximate center of the insert member 23, and is rectangular in plan view and long in the longitudinal direction of the insert member 23. The tip surface of the bulging portion 23a is flat. Positioning holes 23b with a circular cross section are formed on both sides of the bulging portion 23a of the insert member 23 in the longitudinal direction, with a gap between them and the bulging portion 23a. The tip surface of the bulging portion 23a of the insert member 23 is exposed to the back side of the plate-like member 21, while the portion of the insert member 23 except for the tip surface of the bulging portion 23a is embedded in the plate-like member 21.

[0046] 9 and 10 show a method for injection molding a resin molded product according to a second embodiment of the present invention, which is a method for injection molding a plate-like member 21 configured as described above.

[0047] The fixed mold 101 has a surface fixed mold side molding surface 101c which molds the surface of the plate-like member 21, and an end face fixed mold side molding surface 101d which molds approximately half of the surface side of the outer peripheral end surface of the plate-like member 21. The surface fixed mold side molding surface 101c faces approximately vertically downward, while the end face fixed mold side molding surface 101d faces approximately horizontally.

[0048] The movable mold 103 has a rear surface movable mold molding surface 103d which molds the rear surface of the plate-like member 21, and an end surface movable mold molding surface 103e which molds approximately half of the rear surface of the outer peripheral end surface of the plate-like member 21. The rear surface movable mold molding surface 103d faces approximately vertically upward, while the end surface movable mold molding surface 103e faces approximately horizontally.

[0049] The movable mold 103 includes a pair of positioning pins 105, a pair of springs 107, a cam plate 109, and a drive unit (not shown).

[0050] The pair of positioning pins 105 are provided at a distance from each other in the longitudinal direction of the movable back surface mold side molding surface 103d so as to be able to protrude from the movable back surface mold side molding surface 103d.

[0051] The upper surface of the cam plate 109 is in contact with the pair of positioning pins 105 from below (in the retreating direction). On the upper surface of the cam plate 109, two guide surface portions 110 are formed at an interval in the juxtaposition direction of the positioning pins 105 on one side (left side in FIGS. 9 and 10) from the first flat surface portion 109a in the juxtaposition direction of the positioning pins 105 (longitudinal direction of the rear surface movable mold side molding surface 103d) and are each composed of a first flat surface portion 109a, a second flat surface portion 109b located below the first flat surface portion 109a, and an inclined surface portion 109c gradually inclined downward from the first flat surface portion 109a toward the second flat surface portion 109b.

[0052] Cam plate 109 can be slid between a first slide position (position in FIG. 9) and a second slide position (position in FIG. 10) on the other side of the arrangement direction of positioning pins 105 (to the right in FIGS. 9 and 10) from the first slide position by driving a driving device not shown.

[0053] At the first slide position, the cam plate 109 abuts the first flat surface portion 109a against the positioning pin 105, and the tapered portion 105a and the columnar portion 105b of the positioning pin 105 protrude from the back-side movable mold side molding surface 103d of the movable mold 103. When the cam plate 109 is slid from this state toward the second slide position, the positioning pin 105 is guided by the inclined surface portion 109c and moves down (retracts). When the cam plate 109 reaches the second slide position, the second flat surface portion 109b abuts against the positioning pin 105. In this state, the columnar portion 105b of the positioning pin 105 retracts from the back-side movable mold side molding surface 103d of the movable mold 103, and only the entire tapered portion 105a protrudes from the back-side movable mold side molding surface 103d of the movable mold 103.

[0054] In the second embodiment, as shown in Fig. 9, in the preparation state, the cam plate 109 is placed in the first slide position. In this state, the columnar portion 105b of the positioning pin 105 fits into the positioning hole 23b of the insert member 23. In addition, there is a distance D between the tip of the positioning pin 105, i.e., the tapered portion 105a, and the front fixed mold side molding surface 101c of the fixed mold 101.

[0055] In addition, after starting the injection of resin R into cavity C in the preparatory state, until the injection of resin R into cavity C is completed, the cam plate 109 is slid to the second slide position by the driving device, as shown in Figure 10, so that the positioning pin 105 is retracted from the position in the preparatory state in the anti-protruding direction to a predetermined retracted position.

[0056] In this embodiment 2, when the positioning pin 105 is positioned in the above-mentioned retracted position, the tapered portion 105a of the positioning pin 105 does not hinder the release of the plate-like member 21, so the positioning pin 105 is not retracted to a non-protruding position where it does not protrude from the rear-side movable mold side molding surface 103d of the movable mold 103 before the plate-like member 21 is released.

[0057] The rest of the injection molding die 100 and the injection molding method for the plate-like member 21 are similar to those in the first embodiment, so the same components are given the same reference numerals and detailed description thereof will be omitted.

[0058] In the above first and second embodiments, the insert member 15 is made of iron, but it may be made of other metals such as aluminum or brass.

[0059] In the above-mentioned first and second embodiments, the columnar portion 105b of the positioning pin 105 is cylindrical and the tapered portion 105a is conical, but the columnar portion 105b may be rectangular columnar and the tapered portion 105a may be rectangular pyramid. The cross section of the columnar portion 105b may be a shape other than a circle or a square. The tapered portion 105a of the positioning pin 105 may be a shape other than a pyramid. For example, the tapered portion 105a of the positioning pin 105 may be a truncated pyramid shape such as a truncated cone or a truncated pyramid, or may be curved so as to gradually narrow toward the tip.

[0060] In addition, in the first and second embodiments, the positioning holes 19a, 23b of the insert members 15, 23 have a circular cross section, but may have other shapes as long as they can be fitted with the columnar portion 105b of the positioning pin 105.

[0061] Furthermore, in the first and second embodiments, the positioning holes 19a, 23b of the insert members 15, 23 are through holes, but they may be holes with bottoms.

[0062] In addition, in the above embodiments 1 and 2, the fixed mold 101 is positioned above the movable mold 103, and the insert members 15, 23 are placed on the movable mold 103 in a preparatory state, but the movable mold 103 may be positioned above the fixed mold 101, and the insert members 15, 23 may be placed on the fixed mold 101 in a preparatory state.

[0063] Further, in the above-mentioned first and second embodiments, the positioning pin 105 is provided on the movable mold 103, but it may be provided on the fixed mold 101 so as to protrude from the molding surface of the fixed mold 101.

[0064] In addition, in the above embodiments 1 and 2, after the insert members 15, 23 are placed on the movable mold 103, the positioning pin 105 is advanced and inserted into the positioning holes 19a, 23b of the insert members 15, 23. However, after the positioning pin 105 is advanced, the positioning pin 105 may be inserted into the positioning holes 19a, 23b of the insert members 15, 23 to place the insert members 15, 23 on the movable mold 103. [Industrial Applicability]

[0065] The present invention is useful as an injection molding method and an injection molding die for molding a resin molded product into which an insert member is inserted by injecting and filling a cavity formed between a first molding die, a second molding die, and an insert member. [Explanation of symbols]

[0066] 3 Inner panel (plastic molded product) 11a Recess 15 Insert material 19a Positioning hole 21 Plate-shaped components (plastic molded products) 21a Recess 23 Insert material 23b Positioning hole 100 Injection mould 101 Fixed mold (second mold) 101b Fixed mold side second molding surface 101c Fixed mold side molding surface for surface 103 Movable mold (1st mold) 103b Second molding surface on movable mold side 103d Movable mold side molding surface for back side 105 Locating pin 105a Tapered section 105b Column C Cavity D interval R resin S space part

Claims

1. An injection molding method for molding a resin molded product (3, 21) into which an insert member (15, 23) is inserted by injecting and filling a resin (R) into a cavity (C) formed between a first molding die (103) and a second molding die (101) and an insert member (15, 23), the method comprising the steps of: The first mold (103) is provided with a positioning pin (105) having a columnar portion (105b) so as to be protrudible from a molding surface (103b, 103d) of the first mold (103); The insert members (15, 23) are formed with positioning holes (19a, 23b), The insert member (15, 23) is placed on either the first molding die (103) or the second molding die (101), and the peripheral portion of the positioning hole (19a, 23b) of the insert member (15, 23) is opposed to the molding surface (103b, 103d) of the first molding die (103) with a gap therebetween, and the positioning pin (105) is protruded from the molding surface (103b, 103d) of the first molding die (103) to position the insert member (15, 23). and inserting the positioning pin (105) into the positioning hole (19a, 23b) of the insert member (15, 23) so that the columnar portion (105b) of the positioning pin (105) fits into the positioning hole (19a, 23b) of the insert member (15, 23), and in a preparatory state in which the first molding die (103) and the second molding die (101) are clamped, starting injection of resin (R) into the cavity (C).

2. The method for injection molding a resin molded product according to claim 1, a tapered portion (105a) which gradually narrows in the protruding direction is formed at the protruding end of the positioning pin (105) and is continuous with the columnar portion (105b).

3. The method for injection molding a resin molded product according to claim 2, a tapered portion (105a) of the positioning pin (105) and a molding surface (101b, 101c) of the second mold (101) are spaced apart by a distance (D) in the preparation state.

4. The method for injection molding a resin molded product according to any one of claims 1 to 3, The positioning pin (105) is provided so as to be movable forward and backward in a protruding direction and a counter-protruding direction. A method for injection molding a resin molded product, characterized in that, between the start and end of injection of resin (R) into the cavity (C), the positioning pin (105) is retracted from its position in the preparatory state in the anti-protrusion direction to a predetermined retracted position, and the resin (R) is also filled into a space (S) formed by the retraction of the positioning pin (105).

5. The method for injection molding a resin molded product according to claim 4, A tapered portion (105a) that gradually narrows in the protruding direction is formed on the protruding end of the positioning pin (105) and is continuous with the columnar portion (105b). the columnar portion (105b) of the positioning pin (105) is removed from the positioning hole (23b) of the insert member (15, 23) at the retreated position, and the entire tapered portion (105a) is caused to protrude from the molding surface (103b, 103d) of the first mold (103).

6. The method for injection molding a resin molded product according to any one of claims 1 to 5, The positioning pin (105) is provided so as to be movable forward and backward in a protruding direction and a counter-protruding direction. The resin molded product (3, 21) has a recess (11a, 21a), the method for injection molding a resin molded product, characterized in that, before release of the resin molded product (3, 21), the positioning pin (105) is retracted from a position where it engages with a recess (11a, 21a) of the resin molded product (3, 21) thereby preventing release of the resin molded product (3, 21) to a non-protruding position where it does not protrude from the molding surface (103b, 103d) of the first mold (103), thereby enabling the resin molded product (3, 21) to be released.

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