JP5969884B2 - Injection molding equipment - Google Patents

Description

  The present invention relates to an injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material into a cavity formed between a fixed mold and a movable mold.

  Conventionally, in this type of injection molding apparatus, as disclosed in Patent Document 1, etc., fillers (carbon, glass fiber, etc.) for improving the strength of synthetic resin molded products, surface texture improvement and appearance quality improvement Therefore, a molten thermoplastic synthetic resin containing a different material such as a glittering material (aluminum powder, mica, etc.) is used.

Japanese Patent Laid-Open No. 9-1611

  However, as shown in FIGS. 19 to 21, the glitter material 4 as the different material is placed in the cavity 3 formed between the fixed mold 1 as the upper mold and the movable mold 2 as the lower mold. When the molten thermoplastic synthetic resin 5 is injected from a gate (not shown), the glittering material 4 flows in parallel along the flow direction of the synthetic resin 5 indicated by the solid arrow in FIG. In this case, at the flow front ends 5A and 5B of the synthetic resin 5, the glitter material 4 flows in parallel along the front end surface shape of the synthetic resin 5 (see FIG. 20), and eventually the flow front of the synthetic resin 5 In the weld line 6 where the portions 5A and 5B merge, the glittering material 4 is oriented in a direction perpendicular to the flow direction of the synthetic resin 5.

  And when the injection pressure shown by the broken line arrow shown in FIG. 21 is added, the said luminescent material 4 of the said weld line 6 will be orientated in the more perpendicular | vertical direction, and when the said fixed metal mold | die 1 is cooled after that, synthetic resin molded article of An alignment portion L1 centering on the weld line 6 is formed on the surface, and an alignment line extending in the vertical direction along the weld line 6 is formed, so that the appearance of the synthetic resin molded product is deteriorated. It was.

  Moreover, an opening forming body for forming an opening such as a hole in the synthetic resin molded product, a thin formed body for forming a thin portion in the synthetic resin molded product, or a convex for forming a convex portion in the synthetic resin molded product. When the part forming groove is formed in the movable mold or the fixed mold, the glittering material flows in parallel along the flow direction of the synthetic resin behind the opening forming body as viewed from the gate side. Eventually, the bright material is oriented in a direction perpendicular to the flow direction of the synthetic resin in the weld line where the synthetic resin wraps around the opening forming body and the flow front ends merge. Become. Thereafter, when the fixed mold is cooled, an alignment portion centered on the weld line is formed on the surface of the synthetic resin molded product, and an alignment line extending in the vertical direction along the weld line is formed. There was a problem that the appearance of the synthetic resin molded product was deteriorated.

  For this reason, for example, in Patent Document 1, a shearing force is applied in the vicinity of the weld line during molding in order to make the weld line inconspicuous. However, since the flow of the molten synthetic resin due to the shear force is indirect and not so large, the alignment line caused by the dissimilar material being aligned in a direction perpendicular to the flow direction of the molten synthetic resin It was difficult to hide from the outside.

  Therefore, in view of the above points, the present invention is a case where the molten thermoplastic synthetic resin containing the different material is injected into the cavity formed between the fixed mold and the movable mold. Another object of the present invention is to make the orientation line formed along the weld line invisible as much as possible from the outside of the synthetic resin molded product, and to finish the appearance of the synthetic resin molded product satisfactorily.

A first invention is an injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A gate for injecting the synthetic resin into the cavity;
As seen from the gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the convex forming groove behind the opening forming body, the thin-walled forming body, or the convex forming groove and is formed by joining together. The movable mold near the weld line is provided with an elevating pin provided so as to be movable up and down in the cavity,
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, After the synthetic resin is injected from the gate and the injection line is formed on the back side of the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the gate side by the injection , and Before completion of the holding pressure for increasing the compression density of the synthetic resin in the cavity, the upper end surface of the synthetic resin is movable when the injection of the synthetic resin from the gate is started while continuing the injection of the synthetic resin from the gate. The lift pins are raised from a state where they are flush with the cavity forming surface of the mold and entered into the cavity, and then lowered so as to return to the original position .

A second invention is an injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A first gate for injecting the synthetic resin into the cavity;
The synthetic resin is injected from the first gate and intersects the alignment line of the different material formed behind the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the first gate side. A second gate for injecting the synthetic resin;
When viewed from the first gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the convex forming groove behind the opening forming body, the thin-walled forming body, or the convex forming groove and joins each other. An elevating pin provided in the cavity so as to be movable up and down is provided in the movable mold near the weld line formed by
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, After the synthetic resin is injected from the first gate and the alignment line is formed by the injection, and before the holding pressure for increasing the compression density of the synthetic resin in the cavity is completed, the first gate From the state where the upper end surface of the synthetic resin is flush with the cavity forming surface of the movable mold at the start of injection, the lifting pin is lifted to enter the cavity and then returned to the original position. The first gate is closed and the second gate is opened to inject the synthetic resin .

A third invention is an injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A gate for injecting the synthetic resin into the cavity;
As seen from the gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the convex forming groove behind the opening forming body, the thin-walled forming body, or the convex forming groove and is formed by joining together. A first elevating pin provided to be movable up and down in the movable mold in the vicinity of the weld line
A second lifting pin provided to be movable up and down in the movable mold so as to sandwich the weld line with the first lifting pin;
At the start of injection of the synthetic resin by the gate, the first lifting pin has its upper end surface flush with the cavity surface of the mold, and the second lifting pin has its upper end surface flush with the movable mold. The synthetic resin pool space is formed above the second elevating pin as a position below the cavity forming surface,
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, The synthetic resin is injected from the gate , and after the formation of the alignment line of the different material on the back of the opening forming body, the thin forming body, or the convex forming groove as viewed from the gate side by the injection, and the Before the pressure holding to increase the compression density of the synthetic resin in the cavity was completed, the gate was opened and the injection of the synthetic resin was continued, and the first lifting pin was raised to enter the cavity. after the upper end face is lowered so as to have the same flush with the cavity forming surface of the movable mold, and at the same time as the lowering of the first lifting pin, or before or after this descent, the upper end surface of front Characterized in that push the synthetic resin accumulated by raising the second lift pins so as to have the same flush with the cavity-forming surface of the movable mold in the collecting space into the cavity.

A fourth invention is an injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A first gate for injecting the synthetic resin into the cavity;
The synthetic resin is injected from the first gate and intersects the alignment line of the different material formed behind the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the first gate side. A second gate for injecting the synthetic resin;
When viewed from the first gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the protruding portion forming groove behind the opening forming body, the thin-walled forming body, or the protruding portion forming groove, and joins each other. A first elevating pin provided to be movable up and down in the movable mold in the vicinity of the weld line formed by
A second lifting pin provided to be movable up and down in the movable mold so as to sandwich the weld line with the first lifting pin;
At the start of injection of the synthetic resin by the first gate, the first lifting pin has its upper end surface flush with the cavity surface of the mold, and the second lifting pin has its upper end surface flush with the movable metal The synthetic resin pool space is formed above the second lift pins as a position below the cavity forming surface of the mold,
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, After the synthetic resin is injected from the first gate and the alignment line is formed behind the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the first gate side by the injection. And before the pressure holding to increase the compression density of the synthetic resin in the cavity is completed, the first gate is closed and the second gate is opened to start the injection of the synthetic resin, or before and after the start. Then, after the first elevating pin is raised and entered into the cavity, the upper end surface thereof is lowered so as to be flush with the cavity forming surface of the movable mold, and the first Simultaneously with lowering of the lift pins, or before or after this descent, the space reservoir wherein the upper end face is raised the second lift pins so as to have the same flush with the cavity forming surface of the movable mold The collected synthetic resin is pushed up into the cavity.

  According to the present invention, when a molten thermoplastic synthetic resin containing a different material is injected into a cavity formed between a fixed mold and a movable mold, the mold is formed along a weld line. The orientation line can be made as invisible as possible from the outside of the synthetic resin molded product, so that the appearance of the synthetic resin molded product can be satisfactorily finished.

It is schematic structure explanatory drawing which looked at the cavity of the injection molding apparatus of 1st Embodiment from the top. It is AA sectional drawing of FIG. 1 explaining the injection state of the 1st synthetic resin of the state which closed the mold. It is an AA sectional view of Drawing 1 explaining the 2nd synthetic resin injection state similarly. It is the schematic structure explanatory drawing which looked at the cavity of the injection molding apparatus of 2nd Embodiment from the top similarly. FIG. 5 is a cross-sectional view taken along line BB of FIG. 4 before injection of the synthetic resin in the injection molding apparatus in a closed state. It is CC sectional drawing of FIG. 4 explaining a 1st synthetic resin injection state similarly. It is CC sectional drawing of FIG. 4 explaining a 2nd synthetic resin injection state similarly. It is CC sectional drawing of FIG. 4 explaining a 3rd synthetic resin injection state similarly. It is CC sectional drawing of FIG. 4 explaining a 4th synthetic resin injection state similarly. It is the schematic structure explanatory drawing which looked at the cavity of the injection molding apparatus of 3rd Embodiment from the top similarly. It is schematic structure explanatory drawing which looked at the cavity part of the injection molding apparatus of the 4th thru | or 7th embodiment from the top. It is DD sectional drawing of FIG. 11 explaining the 1st synthetic resin injection state of the state which closed the mold. It is DD sectional drawing of FIG. 11 explaining a 2nd synthetic resin injection state similarly. FIG. 12 is a cross-sectional view taken along the line E-E in FIG. 11 for explaining the first synthetic resin injection state. FIG. 12 is a cross-sectional view taken along line EE in FIG. 11 for explaining the second synthetic resin injection state. FIG. 12 is a cross-sectional view taken along line EE in FIG. 11 for explaining the third synthetic resin injection state. It is a longitudinal cross-sectional view of the principal part of the injection molding apparatus of the state which closed the mold | die which shows the example which formed the convex part formation groove | channel etc. in the movable metal mold | die. It is a longitudinal cross-sectional view of the principal part of the injection molding apparatus of the state which closed the mold | die which shows the example which formed the convex part formation groove | channel etc. in the fixed metal mold | die. It is sectional drawing explaining the 1st synthetic resin injection state of the conventional injection molding apparatus. It is sectional drawing explaining the 2nd synthetic resin injection state of the conventional injection molding apparatus. It is sectional drawing explaining the 3rd synthetic resin injection state of the conventional injection molding apparatus.

  Embodiments of the present invention will be described below with reference to the drawings. First, based on FIGS. 1-3, the injection molding apparatus of 1st Embodiment is demonstrated. 1 to 3, a cavity 14 is formed between a fixed mold 12 that is an upper mold having a medium passage 11 for heating and cooling and a movable mold 13 that is a lower mold, and synthetic resin molding is performed. An opening forming body 15 for forming an opening such as a hole in a product is positioned at a substantially central portion of the cavity 14 and protrudes into the cavity 14 so that the upper end surface thereof is in contact with the fixed mold 12. Stands on the mold 13.

  The fixed mold 12 and the movable mold 13 are suitable for a molten thermoplastic synthetic resin 20 (including a different material 19 described later) that is always injected into the cavity 14 by a heating means (not shown). The first predetermined temperature is maintained. In this case, the first predetermined temperature is a temperature lower than the softening point close to the softening point temperature of the synthetic resin 20, and the temperature varies depending on the type of the synthetic resin used. The movable mold 13 may be heated to the same temperature, or any one of them may be heated at different temperatures. The first predetermined temperature in each embodiment to be described later is the same as the first predetermined temperature in the first embodiment, and a description thereof will be omitted.

  A first gate 16 for injecting the molten synthetic resin 20 is provided at the left central portion of the cavity 14 and formed on the right side of the opening forming body 15 when the molten synthetic resin 20 is injected. The alignment line 17A2 of the dissimilar material 19 formed along the weld line 17A1 extending in the up-down direction is made visible to the weld line 17A1 and the alignment line 17A2 so as to be as invisible as possible from the outside in the synthetic resin molded product For example, a second gate 18 for injecting the molten synthetic resin 20 is provided in the central portion on the front side of the cavity 14 so as to face perpendicularly.

  Note that the opening forming body 15 has a tapered shape toward the tip when viewed from the direction of the first gate 16 in plan view, so that the amount of the alignment line 17A2 is small, and the opening The synthetic resin 20 does not flow or does not flow easily near the tip of the formed body 15.

  In addition, the injection of the synthetic resin 20 from the second gate 18 allows the alignment line 17A2 formed on the back side of the opening forming body 15 as viewed from the first gate 16 side to be seen as much as possible from the outside in the synthetic resin molded product. This is to make it disappear. That is, the synthetic resin 20 is ejected radially from the first gate 16 to form the alignment line 17A2 and cross the traveling direction of the synthetic resin 20 ejected from the first gate 16. The synthetic resin 20 is injected from the two gates 18. Therefore, the traveling direction of the synthetic resin 20 injected from the second gate 18 does not necessarily have to be orthogonal to the weld line 17A1 and the alignment line 17A2, and the weld line 17A1 and the alignment line 17A2 It suffices if they intersect, and they may be ejected from an oblique direction.

  The dissimilar material 19 is a bright material (aluminum powder, mica, etc.) for improving the surface texture and appearance quality of the synthetic resin molded product, but a filler (improving the strength of the synthetic resin molded product). Carbon, glass fiber, etc.) may be used.

  Hereinafter, a synthetic resin molding operation in the injection molding apparatus of the first embodiment will be described. First, immediately before the stationary mold 12 and the movable mold 13 are closed while the stationary mold 12 and the movable mold 13 are maintained at the first predetermined temperature, The heating medium is flowed into the medium passage 11 to start heating the fixed mold 12, and the surface temperature of the fixed mold 12 on the side of the cavity 14 is set within the cavity 14, particularly the surface layer portion of the synthetic resin 20 ( The portion close to the cavity forming surface of the fixed mold 12) flows up to a second predetermined temperature within a range from the softening point temperature of the synthetic resin 20 or higher to a temperature at which the characteristics of the synthetic resin 20 can be maintained. .

  Then, as described above, after the heating of the fixed mold 12 is started, the mold is closed, and when the surface temperature on the cavity 14 side of the fixed mold 12 is increased to the second predetermined temperature, The heating of the fixed mold 12 by the medium is stopped, and the molten thermoplastic synthetic resin 20 including the foreign material 19 is injected radially from the first gate 16 by an injection nozzle (not shown).

  Then, when the injection amount of the synthetic resin 20 from the first gate 16 into the cavity 14 increases, the back side of the opening forming body 15 as viewed from the first gate 16 side, that is, the first As shown in FIG. 1, the molten synthetic resin 20 wraps around the opening forming body 15 and merges with each other at a side position of the opening forming body 15 on the side opposite to the side facing the gate 16. The alignment line 17A2 of the dissimilar material 19 is formed along the line 17A1, and the dissimilar material 19 is aligned in the vertical direction in the alignment portion L2 centering on the weld line 17A1 (see FIG. 2).

  That is, as shown in FIG. 2, in the alignment portion L2 in the vicinity of the weld line 17A1, the vertical direction (vertical direction) is different from the traveling direction (horizontal direction) of the synthetic resin 20 injected from the first gate 16. The dissimilar material 19 stands in the direction), and the alignment line 17A2 is formed. In this state, the synthetic resin 20 injected into the cavity 14 is pressurized and the holding pressure for increasing the compression density is not completed, and the compression density is still low. This “completion of pressure holding” means that the synthetic resin 20 injected into the cavity has an appropriate compression density, but the same applies to other embodiments thereafter.

  Then, after the alignment line 17A2 is formed, the first gate 16 is closed and the second gate 18 is replaced before the holding pressure at which the synthetic resin 20 has an appropriate compression density is completed. With the first gate 16 closed and the second gate 18 opened, the molten thermoplastic synthetic resin 20 containing the different material 19 is injected radially. In this case, as long as the orientation line 17A2 is formed and the holding pressure is not completed, not only the injection of the synthetic resin 20 from the first gate 16 is stopped, but also from the first gate 16. The injection of the synthetic resin 20 from the second gate 18 may be started before or after the injection is stopped.

  Then, as shown in FIG. 3, the synthetic resin 20 injected from the second gate 18 flows so as to intersect the weld line 17A1 and the alignment line 17A2, and the synthesis of the alignment portion L2 is performed. The resin 20 is pushed away to the left (see FIG. 3). In this case, the synthetic resin 20 is easy to flow in the surface layer portion on the cavity forming surface side of the fixed mold 12, and is different from the traveling direction (horizontal direction) of the synthetic resin 20 injected from the first gate 16. The dissimilar material 19 standing in the vertical direction is oriented so that it lies as much as possible in the horizontal direction along the direction of travel of the synthetic resin 20 from the vertical direction, and the orientation line 17A2 along the weld line 17A1 is oriented to the synthetic resin molded product. As a result, the appearance of the synthetic resin molded product can be satisfactorily finished.

  When the synthetic resin 20 is continuously injected from the second gate 18 and the cavity 24 is filled with the synthetic resin 20, the compression density of the synthetic resin 20 is increased and pressure holding starts. Is done. Further, when the injection operation is continued, the compression density of the synthetic resin 20 is further increased while maintaining the pressure holding state. During this pressure holding, a cooling medium is placed in the medium passage 11 instead of the heating medium. Then, the fixed mold 12 is cooled to gradually cure the synthetic resin 20. When the compression density becomes uniform and the synthetic resin 20 reaches an appropriate compression density (target compression density), the injection operation of the synthetic resin 50 from the second gate 18 is stopped and the holding pressure is completed. .

  As described above, when the dissimilar material 19 lies in the horizontal direction and the pressure holding of the synthetic resin 20 in the cavity 24 is completed and cured to the extent that it can be taken out as a synthetic resin molded product, the cooling described above is terminated. . Then, mold opening is performed, and the synthetic resin molded product is taken out from the cavity 24.

  Note that, as described above, even if the alignment line 17A2 becomes invisible as much as possible from the outside of the synthetic resin molded product due to the injection of the synthetic resin 20 from the second gate 18, the synthetic resin from the second gate 18 is assured. If a new alignment line different from the alignment line 17A2 is formed by the injection of 20 or if a part of the alignment line 17A2 is visible from the outside, the second gate is completed before the holding pressure is completed. 18 may be in a closed state, and the synthetic resin 20 may be injected with the first gate 16 open.

  Further, even in this case, when a part of the alignment line 17A2 or a part of the other alignment line is visible from the outside, the first gate 16 is closed before the pressure holding is completed. Further, the injection operation by the first gate 16 or the second gate 18 may be repeated by injecting the synthetic resin 20 with the second gate 18 opened and the second gate 18 opened. This ensures that the alignment line 17A2, the other alignment line, and the like are not visible from the outside of the synthetic resin molded product.

  Next, an injection molding apparatus according to the second embodiment will be described with reference to FIGS. A cavity 24 is formed between a fixed mold 22 that is an upper mold and a movable mold 23 that is a lower mold having a medium path 21 that performs the same function as the medium path 11 described in the first embodiment. In the movable mold 23, quadrangular columnar opening forming bodies 25A and 25B for forming openings such as holes in a synthetic resin molded product project into the cavity 24, and the upper end surfaces thereof abut against the fixed mold 22. So that it is erected.

  Further, a gate 26A for injecting a molten thermoplastic synthetic resin 30 containing a different material 29 similar to the above-mentioned different material 19 is provided at the left central portion of the cavity 24, and the right side of the opening forming bodies 25A and 25B. The opening is formed in the vicinity of the weld lines 27A1 and 27B1 formed in the direction and the alignment lines 27A2 and 27B2 of the different material 29, for example, in contact with the right side surfaces of the opening forming bodies 25A and 25B (see FIG. 4). Elevating pins 28A, 28B are disposed in the movable mold 23 at positions adjacent to the bodies 25A, 25B so as to be able to move up and down by the drive mechanism so as to be able to protrude and retract in the cavity 24.

  The elevating pins 28A and 28B are at the same position as the cavity forming surface of the movable mold 23 when the injection of the synthetic resin is started at the start of the molding cycle (see FIG. 5).

  The synthetic resin molding operation in the injection molding apparatus of the second embodiment will be described below. First, in the same manner as in the first embodiment, the fixed mold 22 and the movable mold 23 are in a state where the fixed mold 22 and the movable mold 23 are maintained at the first predetermined temperature. Immediately before the mold is closed, the heating medium is flowed into the medium passage 21 to start heating the fixed mold 22, and the surface temperature of the fixed mold 22 on the cavity 24 side is set in the cavity 24. In particular, a range from the softening point temperature of the synthetic resin 30 at which the surface layer portion of the synthetic resin 30 (the portion near the cavity forming surface of the fixed mold 22) easily flows to a temperature at which the characteristics of the synthetic resin 30 can be maintained. To the second predetermined temperature.

  As described above, when heating of the fixed mold 22 is started, the mold is closed, and when the surface temperature on the cavity 24 side of the fixed mold 22 is raised to the second predetermined temperature, The heating of the fixed mold 22 by the medium is stopped, and the molten thermoplastic synthetic resin 30 including the different material 29 is injected radially from the gate 26A by an injection nozzle (not shown).

  When the injection amount of the molten synthetic resin 30 from the gate 26A into the cavity 24 increases, as viewed from the gate 26A side, on the back of the opening forming bodies 25A and 25B, that is, the gate As shown in FIG. 4, the melted synthetic resin 30 wraps around the opening forming bodies 25A and 25B and joins the opening forming bodies 25A and 25B on the side opposite to the side facing 26A. The alignment lines 27A2 and 27B2 of the dissimilar material 29 are formed along the weld lines 27A1 and 27B1, and the dissimilar material 29 is vertically aligned in the alignment portion L3 centering on the weld lines 27A1 and 27B1 (FIG. 6).

  That is, in the alignment portion L3 in the vicinity of the weld lines 27A1 and 27B1, the dissimilar material 29 is arranged in a vertical direction (vertical direction) different from the traveling direction (horizontal direction) of the synthetic resin 30 injected from the gate 26A. As a result, the alignment lines 27A2 and 27B2 are formed. Further, the stagnation portion where the synthetic resin 30 injected from the gate 26A does not flow or hardly flows near the right side surfaces of the opening forming bodies 25A and 25B in FIG. 4 (particularly, the right base of the opening forming bodies 25A and 25B). U1 and U2 are generated. In this state, the pressure holding of the synthetic resin 30 injected into the cavity 24 is not completed and the compression density is still low.

  In addition, after the alignment lines 27A2 and 27B2 are formed and before the holding pressure is completed, the upper and lower surfaces of the elevating pins 28A and 28B are movable when the injection of the synthetic resin 30 from the gate 26A is started. After moving up to a position that does not reach the cavity forming surface of the fixed mold 22 from being in the same plane as the cavity forming surface of the mold 23 and entering the cavity 24 (see FIG. 7), the movable mold The mold 23 returns to the same level as the cavity forming surface (see FIG. 8).

  In addition, the position of the ascending limit of the elevating pins 28A and 28B is a position where the orientation of the dissimilar material 29 in the synthetic resin 30 thinned by this ascent does not collapse. The raising / lowering operation of the raising / lowering pins 28A and 28B may be performed individually according to the time when the corresponding alignment line is formed, may be raised / lowered at the same time, and even when three or more raising / lowering pins are provided. In addition, the lifting / lowering operation may be performed individually or simultaneously. like this. The raising / lowering operation of the raising / lowering pins 28A, 28B is the same in the third embodiment described later.

  As described above, the lift pins 28A and 28B are raised after the alignment lines 27A2 and 27B2 are formed and before the holding pressure is completed. Therefore, the lift pins 28A and 28B Easy to rise. When the elevating pins 28A and 28B are raised, the weld lines 27A1 and 27B1 and the alignment lines 27A2 and 27B2 are obliquely deformed (see FIG. 7).

  As shown in FIG. 8, when the elevating pins 28A and 28B are lowered before the pressure holding is completed, the weld lines 27A1 and 27B1 and the alignment lines 27A2 and 27B2 are placed in the synthetic resin 30 in the vicinity. A space S1 (the volume of the raised lift pins 28A and 28B in the cavity 24) is formed.

  By continuing the injection of the synthetic resin 30 from the gate 26A, as shown in FIG. 9, the synthetic resin 30 causes the synthetic resin 30 in the vicinity of the weld lines 27A1, 27B1 and the alignment lines 27A2, 27B2 to be The stagnation portions U1 and U2 generated in the vicinity of the right side of the back side of the opening forming bodies 25A and 25B, that is, the portion in contact with the right side are pushed to the right so as to be filled in the space S1 (see FIG. 9).

  Therefore, in this case, the synthetic resin 30 is particularly easy to flow in the surface layer portion on the cavity forming surface side of the fixed mold 22 and is injected from the gate 26A at the orientation portion L3 including the stagnation portions U1 and U2. Further, the dissimilar material 29 standing in the vertical direction different from the traveling direction of the synthetic resin 30 is oriented so that it lays down in the horizontal direction along the traveling direction of the synthetic resin 30 from the vertical direction as much as possible, and the weld lines 27A1, 27B1 The alignment lines 27A2 and 27B2 along the line are made invisible as much as possible from the outside of the synthetic resin molded product, so that the appearance of the synthetic resin molded product can be satisfactorily finished.

  When the operation of injecting the synthetic resin 30 from the gate 26A is continued and the synthetic resin 30 is filled into the cavity 24, the compression density of the synthetic resin 30 is increased and pressure holding is started. . Further, if the injection operation is continued, the compression density of the synthetic resin 30 is further increased while maintaining the pressure holding state. During this pressure holding, a cooling medium is placed in the medium passage 21 instead of the heating medium. Then, the fixed mold 22 is cooled to gradually cure the synthetic resin 30. When the compression density becomes uniform and the synthetic resin 30 reaches an appropriate compression density (target compression density), the injection operation of the synthetic resin 30 from the gate 26A is stopped and the holding pressure is completed.

  As described above, when the dissimilar material 29 lies in the horizontal direction and the pressure holding of the synthetic resin 30 in the cavity 24 is completed and cured to the extent that it can be taken out as a synthetic resin molded product, the cooling described above is terminated. . Then, mold opening is performed, and the synthetic resin molded product is taken out from the cavity 24.

  As described above, a part of the alignment lines 27A2 and 27B2 can be seen from the outside of the synthetic resin molded product even though the elevating pins 28A and 28B are raised and lowered before the holding pressure is completed. In some cases, the lifting pins 28A and 28B may be raised and lowered repeatedly as many times as necessary before the pressure holding is completed. Thereby, the alignment lines 27A2 and 27B2 are not visible from the outside of the synthetic resin molded product.

  Next, the injection molding apparatus according to the third embodiment will be described with reference to FIG. 10. The difference from the second embodiment is that other gates 26B and 26B are provided in addition to the gate 26A. Therefore, the sectional views related to the opening forming bodies 25A and 25B in the injection molding apparatus of the third embodiment are the same as those in FIGS. 5 to 9 of the second embodiment. 5-9 is used also in a form.

  That is, the alignment lines 27A2 and 27B2 of the dissimilar material 29 extending in the vertical direction formed on the right side of the opening forming bodies 25A and 25B (see FIG. 10) by injection of the molten synthetic resin 30 from the gate 26A. In the synthetic resin molded product, for example, so that the weld lines 27A1, 27B1 and the alignment lines 27A2, 27B2 intersect (for example, orthogonally cross) the alignment lines 27A2, 27B2. Correspondingly, gates 26B and 26B for injecting the molten synthetic resin 30 radially are provided in the middle part on the back side of the cavity 24 in FIG.

  In the third embodiment, the injection of the synthetic resin 30 from the gates 26B and 26B is performed on the alignment lines 27A2 and 27B2 formed behind the opening forming bodies 25A and 25B when viewed from the gate 26A side. This is to make the synthetic resin molded product invisible as much as possible from the outside. That is, the synthetic resin 30 is injected from the gate 26A to form the alignment lines 27A2 and 27B2, and from the gates 26B and 26B so as to intersect the traveling direction of the synthetic resin 30 injected from the gate 26A. The synthetic resin 30 is injected. For this reason, the traveling direction of the synthetic resin 30 injected from the gates 26B and 26B does not necessarily have to be orthogonal to the weld lines 27A1 and 27B1 and the alignment lines 27A2 and 27A2, and the weld lines 27A1 and 27B1. And the alignment lines 27A2 and 27B2 may be crossed, and the light may be emitted from an oblique direction.

  Hereinafter, a synthetic resin molding operation in the injection molding apparatus of the third embodiment will be described. First, in the same manner as in the first embodiment, the fixed mold 22 and the movable mold 23 are in a state where the fixed mold 22 and the movable mold 23 are maintained at the first predetermined temperature. Immediately before the mold is closed, the heating medium is flowed into the medium passage 21 to start heating the fixed mold 22, and the surface temperature of the fixed mold 22 on the cavity 24 side is set in the cavity 24. In particular, a range from the softening point temperature of the synthetic resin 30 at which the surface layer portion of the synthetic resin 30 (the portion near the cavity forming surface of the fixed mold 22) easily flows to a temperature at which the characteristics of the synthetic resin 30 can be maintained. To the second predetermined temperature.

  As described above, when heating of the fixed mold 22 is started, the mold is closed, and when the surface temperature on the cavity 24 side of the fixed mold 22 is raised to the second predetermined temperature, The heating of the fixed mold 22 by the medium is stopped, and the molten thermoplastic synthetic resin 30 including the different material 29 is injected radially from the gate 26A by an injection nozzle (not shown).

  When the injection amount of the molten synthetic resin 30 from the gate 26A into the cavity 24 increases, as viewed from the gate 26A side, the back side of the opening forming bodies 25A, 25B, that is, the As shown in FIG. 10, the melted synthetic resin 30 wraps around the opening forming bodies 25A and 25B at the side positions of the opening forming bodies 25A and 25B opposite to the side facing the gate 26A. The alignment lines 27A2 and 27B2 are formed along the weld lines 27A1 and 27B1 to be joined, and the dissimilar material 29 is vertically aligned in the alignment portion L3 centering on the weld lines 27A1 and 27B1 (see FIG. 6). .

  That is, in the alignment portion L3 in the vicinity of the weld lines 27A1 and 27B1, the dissimilar material 29 is arranged in a vertical direction (vertical direction) different from the traveling direction (horizontal direction) of the synthetic resin 30 injected from the gate 26A. As a result, the alignment lines 27A2 and 27B2 are formed. Further, the stagnation portion where the synthetic resin 30 injected from the gate 26A does not flow or hardly flows near the right side surface of the opening forming bodies 25A and 25B (particularly, the right base of the opening forming bodies 25A and 25B) in FIG. U1 and U2 are generated. In this state, the pressure holding of the synthetic resin 30 injected into the cavity 24 is not completed and the compression density is still low.

  In addition, after the alignment lines 27A2 and 27B2 are formed and before the holding pressure is completed, the upper and lower surfaces of the elevating pins 28A and 28B are movable when the injection of the synthetic resin 30 from the gate 26A is started. After moving up to a position that does not reach the cavity forming surface of the fixed mold 22 from being in the same plane as the cavity forming surface of the mold 23 and entering the cavity 24 (see FIG. 7), the movable mold The mold 23 returns to the same level as the cavity forming surface (see FIG. 8).

  As described above, the lift pins 28A and 28B are raised after the alignment lines 27A2 and 27B2 are formed and before the holding pressure is completed. Therefore, the lift pins 28A and 28B Easy to rise. When the elevating pins 28A and 28B are raised, the weld lines 27A1 and 27B1 and the alignment lines 27A2 and 27B2 are obliquely deformed (see FIG. 7).

  As shown in FIG. 8, when the elevating pins 28A and 28B are lowered before the pressure holding is completed, the weld lines 27A1 and 27B1 and the alignment lines 27A2 and 27B2 are placed in the synthetic resin 30 in the vicinity. A space S1 (the volume of the raised lift pins 28A and 28B in the cavity 24) is formed.

  After the elevating pins 28A and 28B are lowered, the injection of the synthetic resin 30 from the gate 26A is stopped, the synthetic resin 30 is injected from the gates 26B and 26B, and the gate 26A is closed. At the same time, the gates 26B and 26B are opened so as to inject the synthetic resin 30, and the synthetic resin 30 is in the vicinity of the weld lines 27A1 and 27B1 and the alignment lines 27A2 and 27B2, as shown in FIG. The stagnation portions U1 and U2 generated in the vicinity of the right side of the back side of the opening forming bodies 25A and 25B, that is, the portion in contact with the right side are pushed to the right so as to fill the synthetic resin 30 in the space S1 (FIG. 9). reference).

  In this case, the synthetic resin 30 has a surface layer portion on the cavity forming surface side of the fixed mold 22 that is particularly easy to flow, and in the orientation portion L3 including the stagnation portions U1 and U2, the synthetic resin 30 is injected from the gate 26A. The dissimilar material 29 standing in the vertical direction different from the traveling direction of the synthetic resin 30 is oriented so as to lie as much as possible in the horizontal direction along the traveling direction of the synthetic resin 30 from the vertical direction, and along the weld lines 27A1 and 27B1. The orientation lines 27A2 and 27B2 can be made invisible as much as possible from the outside of the synthetic resin molded product, so that the appearance of the synthetic resin molded product can be satisfactorily finished.

  When the synthetic resin 30 is continuously injected from the gates 26B and 26B and the cavity 24 is filled with the synthetic resin 30, the compression density of the synthetic resin 30 is increased and pressure holding starts. Is done. Further, if the injection operation is continued, the compression density of the synthetic resin 30 is further increased while maintaining the pressure holding state. During this pressure holding, a cooling medium is placed in the medium passage 21 instead of the heating medium. Then, the fixed mold 22 is cooled to gradually cure the synthetic resin 30. When the compression density becomes uniform and the synthetic resin 30 reaches an appropriate compression density (target compression density), the injection operation of the synthetic resin 30 from the gates 26B and 26B is stopped, and the pressure holding is completed. .

  Note that after the elevating pins 28A and 28B are lowered, the injection of the synthetic resin 30 from the gate 26A is stopped and the injection of the synthetic resin 30 from the gates 26B and 26B is started. I can't. That is, the gate 26A may be closed and the gates 26B and 26B may be opened while the elevating pins 28A and 28B are lowered, and the synthetic resin 30 from the gates 26B and 26B may be opened. The injection may be started before the above-described ascending or descending operation of the elevating pins 28A and 28B. In any of the above cases, the stop of injection of the synthetic resin 40 from the gate 26A and the start of injection of the synthetic resin 30 from the gates 26B and 26B do not necessarily have to be simultaneous. May be early or late.

  As described above, when the dissimilar material 29 lies in the horizontal direction and the pressure holding of the synthetic resin 30 in the cavity 24 is completed and cured to the extent that it can be taken out as a synthetic resin molded product, the cooling described above is terminated. . Then, mold opening is performed, and the synthetic resin molded product is taken out from the cavity 24.

  As described above, a part of the alignment lines 27A2 and 27B2 can be seen from the outside of the synthetic resin molded product even though the elevating pins 28A and 28B are raised and lowered before the holding pressure is completed. In this case, the lifting pins 28A and 28B may be raised and lowered while continuing the injection operation of the synthetic resin 30 from the gates 26B and 26B before the pressure holding is completed. Furthermore, if necessary, the raising / lowering operation of the raising / lowering pins 28A, 28B may be repeated while continuing the injection operation of the synthetic resin 30 from the gates 26B, 26B. As a result, the alignment line and the like are surely not visible from the outside of the synthetic resin molded product.

  Next, based on FIGS. 11-16, the injection molding apparatus of 4th Embodiment (refer especially the right part in FIG. 11) and 5th Embodiment (refer especially the left part in FIG. 11) is demonstrated. A cavity 34 is formed between a fixed mold 32 that is an upper mold and a movable mold 33 that is a lower mold having a medium path 31 that performs the same function as the medium path 11 described in the first embodiment. In the movable mold 33, prismatic opening forming bodies 35A and 35B for forming openings such as holes in a synthetic resin molded product project into the cavity 34, and the upper end surface thereof contacts the fixed mold 32. Standing to touch.

  Further, as shown in FIG. 11, a gate 36 for injecting a molten thermoplastic synthetic resin 40 containing a different material 39 similar to the different material 19 is provided at the left central portion of the cavity 34. Further, in the vicinity of the weld line 37A1 formed on the right side of the opening forming body 35A and the alignment line 37A2 of the different material 39, for example, in contact with the right side surface (see FIG. 11) of the opening forming body 35A. Lift pins 38A and 38B are provided in the cavity 34 so as to be movable up and down adjacent to the opening forming body 35A. The elevating pins 38A and 38B are disposed on the movable mold 33 so as to sandwich the weld line 37A1.

  Further, in the vicinity of the weld line 37B1 formed on the right side of the opening forming body 35B and the alignment line 37B2 of the different material 39, for example, in contact with the right side surface of the opening forming body 35B (see FIG. 11), Elevating pins 38C are provided on the movable mold 33 at a position adjacent to the opening forming body 35B.

  The elevating pins 38A, 38B, 38C can be moved up and down by a drive mechanism (not shown). At the start of injection of the synthetic resin 40 at the start of the molding cycle, the upper end surfaces of the elevating pins 38A, 38C are movable. The synthetic resin pool spaces P1 and P2 can be formed above the elevating pins 38A and 38C at a position below the cavity forming surface of the mold 33 (see FIGS. 12 and 14). The upper and lower pins 38B are in the same position as the cavity forming surface of the movable mold 33 (see FIG. 14).

  Hereinafter, a synthetic resin molding operation in the injection molding apparatuses of the fourth and fifth embodiments will be described. First, in the same manner as in the first embodiment, the fixed mold 32 and the movable mold 33 are placed in a state where the fixed mold 32 and the movable mold 33 are maintained at the first predetermined temperature. Immediately before the mold closing, the heating medium is flowed into the medium passage 31 to start heating the fixed mold 32, and the surface temperature of the fixed mold 32 on the side of the cavity 34 is set in the cavity 34. In particular, the range from the softening point temperature of the synthetic resin 40 at which the surface layer portion of the synthetic resin 40 (the portion near the cavity forming surface of the fixed mold 32) easily flows to the temperature at which the characteristics of the synthetic resin 40 can be maintained. To the second predetermined temperature.

  As described above, the heating of the fixed mold 32 is started and then the mold is closed, and when the surface temperature on the cavity 34 side of the fixed mold 32 is raised to the second predetermined temperature, The heating of the fixed mold 32 by the medium is stopped, and the molten thermoplastic synthetic resin 40 including the different material 39 is injected radially from the gate 36 by an injection nozzle (not shown).

  When the injection amount of the melted synthetic resin 40 from the gate 36 into the cavity 34 increases, as viewed from the gate 36 side, on the back of the opening forming body 35A, that is, the gate 36. As shown in FIGS. 11 and 14, a weld line 37A1 in which the synthetic resin 40 wraps around the opening forming body 35A and merges with each other at a side position of the opening forming body 35A opposite to the side facing the surface. The alignment line 37A2 of the dissimilar material 39 is formed along the alignment line L, and the dissimilar material 39 is aligned in the vertical direction in the alignment portion L5 with the weld line 37A1 as the center.

  That is, the dissimilar material 39 stands in a vertical direction (vertical direction) different from the traveling direction (horizontal direction) of the synthetic resin 40 injected from the gate 36 in the alignment portion L5 in the vicinity of the weld line 37A1. The alignment line 37A2 is formed. Further, a stagnation portion U3 in which the synthetic resin 40 injected from the gate 36 does not flow or hardly flows is generated near the right side surface of the opening forming body 35A in FIG. 11 (particularly, the right base of the opening forming body 35A). To do. In this state, the pressure holding of the synthetic resin 40 injected into the cavity 34 is not completed and the compression density is still low.

  In the same manner as described above, when the injection amount of the molten synthetic resin 40 from the gate 36 into the cavity 34 increases, the back of the opening forming body 35B is seen from the gate 36 side. That is, as shown in FIGS. 11 and 12, the synthetic resin 40 wraps around the opening forming body 35B at the side position of the opening forming body 35B opposite to the side facing the gate 36 to each other. The alignment line 37B2 of the dissimilar material 39 is formed along the weld line 37B1 that joins, and the dissimilar material 39 is aligned in the vertical direction in the alignment portion L4 centering on the weld line 37B1.

  That is, in the alignment portion L4 in the vicinity of the weld line 37B1, the dissimilar material 39 stands in a vertical direction (vertical direction) different from the traveling direction (horizontal direction) of the synthetic resin 40 injected from the gate 36. The alignment line 37B2 is formed. Further, a stagnation portion U4 in which the synthetic resin 40 injected from the gate 36 does not flow or hardly flows is generated near the right side surface of the opening forming body 35B in FIG. 11 (particularly, the right base of the opening forming body 35B). To do. In this state, the pressure holding of the synthetic resin 40 injected into the cavity 34 is not completed and the compression density is still low.

  Then, after the alignment line 37A2 is formed and before the pressure holding is completed, the injection of the synthetic resin 40 from the gate 36 is continued and the elevating pin 38B is moved to the cavity forming surface of the fixed mold 32. After being moved up to a position that does not reach the cavity 34 and entering the cavity 34 (see FIG. 15), immediately lowered to a position that is flush with the cavity forming surface of the movable mold 33, one of the weld lines 37A1 A space S2 is formed on the side (see FIGS. 15 and 16). The upper limit position of the elevating pin 38B is a position where the orientation of the different material 39 in the synthetic resin 40 thinned by the ascent is not lost.

  Further, simultaneously with the lowering of the elevating pin 38B, when the elevating pin 38A is raised until its upper end surface is flush with the cavity forming surface of the movable mold 33 (see FIG. 16), the inside of the pool space P1. The synthetic resin 40 stored in the cavity 34 is pushed up into the cavity 34 so that the synthetic resin 40 in the vicinity of the weld line 37A1 is buried in the space S2, and in the vicinity of the right side surface behind the opening forming body 35A. That is, the stagnation portion U3 generated at the position in contact with the right side is pushed to the right (see FIG. 16).

  Therefore, in this case, the synthetic resin 40 has a surface layer portion on the cavity forming surface side of the fixed mold 32 that is particularly easy to flow, and the injection of the synthetic resin 40 from the gate 36 in the orientation portion L5 including the stagnation portion U3. The dissimilar material 39 standing in the vertical direction different from the traveling direction of the synthetic resin 40 is oriented so as to lie as much as possible in the horizontal direction along the traveling direction of the synthetic resin 40 from the vertical direction, and the alignment line 37A2 is formed in the synthetic resin molding The appearance of the synthetic resin molded product can be satisfactorily finished without being visible as much as possible from the outside of the product.

  Similarly to the above, after the alignment line 37B2 is formed and before the pressure holding is completed, the injection of the synthetic resin 40 from the gate 36 is continued, and the upper and lower surfaces of the elevating pin 38C are movable. When the mold 33 is raised to a position that is flush with the cavity forming surface of the mold 33 (see FIG. 13), the synthetic resin 40 stored in the pool space P2 is pushed up into the cavity 34 near the weld line 37B1. Then, the synthetic resin in the vicinity of the weld line 37B1 is swept away, and the stagnation portion U4 generated near the right side of the back of the opening forming body 35B, that is, the portion in contact with the right side is swollen to the right (see FIG. 13).

  Therefore, in this case, the synthetic resin 40 has a surface layer portion on the cavity forming surface side of the fixed mold 32 that is particularly easy to flow, and in the orientation portion L4 including the stagnation portion U4, the synthetic resin 40 is injected from the gate 36. The dissimilar material 39 standing in the vertical direction different from the traveling direction of the synthetic resin 40 is oriented so as to lie as much as possible in the horizontal direction along the traveling direction of the synthetic resin 40 from the vertical direction, and the alignment line 37B2 is formed in the synthetic resin molding The appearance of the synthetic resin molded product can be satisfactorily finished without being visible as much as possible from the outside of the product.

  In addition, the raising / lowering operation of the one or more lifting pins corresponding to the opening forming body as described above is similarly applied to the case where the number of the opening forming bodies is increased, and the increased opening forming body. Each lifting pin increases with the number. The same applies to sixth and seventh embodiments described later.

  When the synthetic resin 40 is continuously injected from the gate 36 and the cavity 34 is filled with the synthetic resin 40, the compression density of the synthetic resin 40 is increased and pressure holding is started. . Further, if the injection operation is continued, the compression density of the synthetic resin 40 is further increased while maintaining the pressure holding state. During this pressure holding, a cooling medium is replaced in the medium passage 31 instead of the heating medium. Then, the fixed mold 32 is cooled to gradually cure the synthetic resin 40. When the compression density becomes uniform and the synthetic resin 40 reaches an appropriate compression density (target compression density), the injection operation of the synthetic resin 30 from the gate 36 is stopped and the holding pressure is completed.

  As described above, when the dissimilar material 39 lies in the horizontal direction and the pressure holding of the synthetic resin 40 in the cavity 34 is completed and cured to the extent that it can be taken out as a synthetic resin molded product, the cooling described above is terminated. . Then, mold opening is performed, and the synthetic resin molded product is taken out from the cavity 34.

  As described above, when a part of the alignment line 37B2 can be seen from the outside of the synthetic resin molded product even though the elevating pin 38C is raised before the holding pressure is completed, Before the pressure holding is completed, the movable pin 38C is lowered so as to form the pool space P2 of the synthetic resin 40 while continuing the injection operation of the synthetic resin 40 from the gate 36, and then the movable metal You may make it raise until it becomes the same surface as the cavity formation surface of the type | mold 33. FIG. Furthermore, if necessary, the descent and ascending operations of the elevating pin 38C may be repeated while the injection operation of the synthetic resin 40 from the gate 36 is continued before the pressure holding is completed. . As a result, the alignment line and the like are surely not visible from the outside of the synthetic resin molded product.

  Similarly, before the pressure holding is completed, the elevating pin 38B is raised so as to enter the cavity 34, and the upper end surface of the elevating pin 38A is the cavity forming surface of the movable mold 33. Although the raising and lowering pins 38B are raised until they are flush with each other and their upper end faces are flush with the cavity forming surface of the movable mold 33, a part of the orientation line 37A2 is When visible from the outside of the synthetic resin molded product, the elevating pin 38B enters the cavity 34 while continuing the injection operation of the synthetic resin 40 from the gate 36 before the pressure holding is completed. Further, the elevating pin 38A is lowered so as to form the synthetic resin pool space P1 above the upper and lower pins 38A. The upper end surface of the lift pin 38B with is increased to the same flush with Yabiti forming surface may be caused to descend until the same flush with the cavity forming surface of the movable mold 33. Further, if necessary, the raising / lowering operation of the raising / lowering pins 38A, 38B is repeated while the injection operation of the synthetic resin 40 from the gate 36 is continued before the pressure holding is completed. Also good. As a result, the alignment line and the like are surely not visible from the outside of the synthetic resin molded product.

  In the fourth and fifth embodiments based on FIGS. 11 to 16 described above, the other gates 36A and 36A (shown by dotted lines in FIG. 11) for making the alignment lines 37A2 and 37B2 invisible as much as possible from the outside. .) May be provided corresponding to the alignment lines 37A2 and 37B2 at a predetermined interval in the middle part on the back side of the cavity 34, and the other gates 36A and 36A are provided (FIG. 6). 11, particularly the right part) and the molding operation of the synthetic resin in the injection molding apparatus of the seventh embodiment (particularly, the left part in FIG. 11) will be described.

  In the sixth and seventh embodiments, the injection of the synthetic resin 40 from the gates 36A and 36A is performed on the dissimilar material formed behind the opening forming bodies 35A and 35B as viewed from the gate 36 side. This is to prevent the 39 alignment lines 37A2 and 37B2 from being seen from the outside as much as possible in the synthetic resin molded product.

  That is, the synthetic resin 40 is injected from the gate 36 to form the alignment lines 37A2 and 37B2, and the different material 39 standing in a vertical direction different from the traveling direction of the synthetic resin 40 injected from the gate 36 is The synthetic resin 40 is ejected radially from the gates 36A and 36A so as to be oriented as much as possible in the horizontal direction along the traveling direction of the synthetic resin 40 from the vertical direction. For this reason, the traveling direction of the synthetic resin 40 injected from the gates 36A and 36A does not necessarily have to be orthogonal to the weld lines 37A1 and 37B1 and the alignment lines 37A2 and 37B2, and the weld lines 37A1 and 37B1. And the alignment lines 37A2 and 37B2 may be crossed, and the light may be emitted from an oblique direction.

  First, in the same manner as in the first embodiment, the fixed mold 32 and the movable mold 33 are placed in a state where the fixed mold 32 and the movable mold 33 are maintained at the first predetermined temperature. Immediately before the mold closing, the heating medium is flowed into the medium passage 31 to start heating the fixed mold 32, and the surface temperature of the fixed mold 32 on the side of the cavity 34 is set in the cavity 34. In particular, within a range from the softening point temperature of the synthetic resin 40 at which the surface layer portion of the synthetic resin 40 (the portion near the cavity forming surface of the fixed mold 32) easily flows to a temperature at which the characteristics of the synthetic resin can be maintained. To the second predetermined temperature.

  As described above, the heating of the fixed mold 32 is started and then the mold is closed, and when the surface temperature on the cavity 34 side of the fixed mold 32 is raised to the second predetermined temperature, The heating of the fixed mold 32 by the medium is stopped, and the molten thermoplastic synthetic resin 40 including the different material 39 is injected radially from the gate 36 by an injection nozzle (not shown).

  When the injection amount of the melted synthetic resin 40 from the gate 36 into the cavity 34 increases, as viewed from the gate 36 side, on the back of the opening forming body 35A, that is, the gate 36. As shown in FIGS. 11, 12, and 14, the synthetic resin 40 wraps around the opening forming bodies 35A and 35B at the side position of the opening forming body 35A opposite to the side facing the surface. The alignment lines 37A2 and 37B2 are formed along the weld lines 37A1 and 37B1 to be joined, and the dissimilar material 39 is vertically aligned in the alignment portions L5 and L4 centering on the weld lines 37A1 and 37B1.

  That is, in the alignment portions L5 and L4 in the vicinity of the weld lines 37A1 and 37B1, the different materials are arranged in a vertical direction (vertical direction) different from the traveling direction (horizontal direction) of the synthetic resin 40 injected from the gate 36. 39 stands and the alignment lines 37A2 and 37B2 are formed. Further, the synthetic resin 40 injected from the gate 36 does not flow or hardly flows near the right side surfaces of the opening forming bodies 35A and 35B in FIG. 11 (particularly, the right base of the opening forming bodies 35A and 35B). Portions U3 and U4 are generated. In this state, the pressure holding of the synthetic resin 40 injected into the cavity 34 is not completed and the compression density is still low.

  Then, after the alignment line 37A2 is formed and before the holding pressure is completed, the elevating pin 38B is fixed to the fixed mold 32 in a state where the injection of the synthetic resin 40 from the gate 36 is continued. It is raised to a position that does not reach the cavity forming surface and enters the cavity 34 (see FIG. 15). Immediately after the entry, the space S2 is formed on one side of the weld line 37A1 when it is lowered to a position that is flush with the cavity forming surface of the movable mold 33 (see FIGS. 15 and 16). The upper limit position of the elevating pin 38B is a position where the orientation of the different material 39 in the synthetic resin 40 thinned by the ascent is not lost.

  Further, simultaneously with the lowering of the elevating pin 38B, the elevating pin 38A is raised until its upper end surface is flush with the cavity forming surface of the movable mold 33, and the synthetic resin 40 is injected from the gate 36. And the synthetic resin 40 melted from the corresponding gate 36A (left gate in FIG. 11) is injected into the cavity 34 instead (see FIG. 16). Then, the synthetic resin 40 stored in the pool space P1 is pushed up into the cavity 34 so that the synthetic resin 40 in the vicinity of the weld line 37A1 is buried in the space S2 and the opening forming body. The stagnation portion U3 generated in the vicinity of the right side of the back side of 35A, that is, the portion in contact with the right side is pushed away to the right (see FIG. 16).

  As described above, after the alignment line 37A2 is formed and before the holding pressure is completed, the elevating pin 38A is raised simultaneously with the lowering of the elevating pin 38B, and the synthetic resin is fed from the gate 36. The injection of 40 is stopped and the molten synthetic resin 40 is injected from the corresponding gate 36A. However, the timing is not limited to this. That is, the gate 36 may be closed and the gate 36A may be opened while the lift pin 38B is lowered and the lift pin 38A is lifted. That is, after the alignment line 37A2 is formed and before the holding pressure is completed, the raising and lowering of the raising / lowering pin 38B and the raising / lowering immediately before or after the injection of the synthetic resin 40 from the corresponding gate 36A is started. The pins 38A may be raised at the same time, the lift pins 38A may be lifted after the lift pins 38B are lowered, or the lift pins 38B may be lowered after the lift pins 38A are lifted. In any of the above cases, the stop of the injection of the synthetic resin 40 from the gate 36 and the start of the injection of the synthetic resin 40 from the gates 36A and 36A do not necessarily have to be simultaneous. May be early or late.

  Therefore, in this case, the synthetic resin 40 has a surface layer portion on the cavity forming surface side of the fixed mold 32 that is particularly easy to flow, and the injection of the synthetic resin 40 from the gate 36 in the orientation portion L5 including the stagnation portion U3. The dissimilar material 39 standing in the vertical direction different from the traveling direction of the synthetic resin 40 is oriented so that it lies as much as possible in the horizontal direction along the traveling direction of the synthetic resin 40 from the vertical direction, and the alignment line 37A2 is formed in the synthetic resin molding. The appearance of the synthetic resin molded product can be satisfactorily finished without being visible as much as possible from the outside of the product.

  Similarly to the above, after the alignment line 37B2 is formed and before the pressure holding is completed, the elevating pin 38C is moved to a position where the upper end surface thereof is flush with the cavity forming surface of the movable mold 33. Simultaneously, the injection of the synthetic resin 40 from the gate 36 is stopped and the molten synthetic resin 40 is injected into the cavity 34 from the corresponding gate 36A (the right gate in FIG. 11) (see FIG. 13). ), The synthetic resin 40 stored in the pool space P2 is pushed up into the cavity 34 near the weld line 37B1, and the synthetic resin 40 in the vicinity of the weld line 37B1 is swept away, and the opening forming body 35B The stagnation portion U4 generated in the vicinity of the right side surface of the back side, that is, the portion in contact with the right side is pushed away to the right (see FIG. 13).

  As described above, after the alignment line 37B2 is formed and before the pressure holding is completed, the injection of the synthetic resin 40 from the gate 36 is stopped simultaneously with the ascent of the elevating pin 38C. The synthetic resin 40 melted from the gate 36A is injected into the cavity 34, but is not limited to this timing. That is, the gate 36 may be closed and the gate 36A may be opened while the elevating pin 38C is raised. After the alignment line 37B2 is formed, before the pressure holding is completed. Further, the injection of the synthetic resin 40 from the gate 36 is stopped, and after the synthetic resin 40 melted from the corresponding gate 36A is injected into the cavity 34, the elevating pin 38C is raised. Good. In any of the above cases, the stop of the injection of the synthetic resin 40 from the gate 36 and the start of the injection of the synthetic resin 40 from the gates 36A and 36A do not necessarily have to be simultaneous. May be early or late.

  Therefore, in this case, the synthetic resin 40 has a surface layer portion on the cavity forming surface side of the fixed mold 32 that is particularly easy to flow, and in the orientation portion L4 including the stagnation portion U4, the synthetic resin 40 is injected from the gate 36. The dissimilar material 39 standing in the vertical direction different from the traveling direction of the synthetic resin 40 is oriented so as to lie as much as possible in the horizontal direction along the traveling direction of the synthetic resin 40 from the vertical direction, and the alignment line 37B2 is formed in the synthetic resin molding. The appearance of the synthetic resin molded product can be satisfactorily finished without being visible as much as possible from the outside of the product.

  When the operation of injecting the synthetic resin 40 from the gate 36A is continued and the synthetic resin 40 is filled into the cavity 34, the compression density of the synthetic resin 40 is increased and pressure holding is started. . Further, if the injection operation is continued, the compression density of the synthetic resin 40 is further increased while maintaining the pressure holding state. During this pressure holding, a cooling medium is replaced in the medium passage 31 instead of the heating medium. Then, the fixed mold 32 is cooled to gradually cure the synthetic resin 40. When the compression density becomes uniform and the synthetic resin 40 reaches an appropriate compression density (target compression density), the injection operation of the synthetic resin 30 from the gate 36A is stopped and the holding pressure is completed. The start of injection of the synthetic resin 40 from the gate 36A instead of the gate 36 may be before or after the above-described lifting operation of the lifting pins 38A, 38B, 38C.

  As described above, when the dissimilar material 39 lies in the horizontal direction and the pressure holding of the synthetic resin 40 in the cavity 34 is completed and cured to the extent that it can be taken out as a synthetic resin molded product, the cooling described above is terminated. . Then, mold opening is performed, and the synthetic resin molded product is taken out from the cavity 34.

  As described above, before the holding pressure is completed, the synthetic resin 40 is injected into the cavity 34 from the corresponding gate 36A (the right gate in FIG. 11) or the lift pin 38C is raised. In spite of the above, if a part of the alignment line 37B2 is visible from the outside of the synthetic resin molded product, the injection operation of the synthetic resin 40 from the gate 36A is continued before the pressure holding is completed. However, the elevating pin 38C may be lowered to form the synthetic resin pool space P2 and then raised until it is flush with the cavity forming surface of the movable mold 33. Furthermore, if necessary, the descent and ascending operations of the elevating pins 38C may be repeated in a state where the injection operation of the synthetic resin 40 from the gate 36A is continued before the holding pressure is completed. . As a result, the alignment line and the like are surely not visible from the outside of the synthetic resin molded product.

  Similarly, before the pressure holding is completed, the elevating pin 38B is raised so as to enter the cavity 34, and the upper end surface of the elevating pin 38A is the cavity forming surface of the movable mold 33. The raising and lowering pins 38B are raised until they are flush with each other, and the upper end faces thereof are lowered until they are flush with the cavity forming surface of the movable mold 33, and the corresponding gate 36A (the left gate in FIG. 11). In some cases, a part of the alignment line 37A2 can be seen from the outside of the synthetic resin molded product, even though the synthetic resin 40 is injected into the cavity 34. In this case, before the pressure holding is completed, the elevating pin 38B is raised so as to enter the cavity 34 while continuing the injection operation of the synthetic resin 40 from the gate 36A, and further the elevating / lowering is performed. After the pin 38A is lowered to form the synthetic resin pool space P1 above the pin 38A, the upper end surface thereof is raised until it is flush with the cavity forming surface of the movable mold 33, and the elevating pin 38B. May be lowered until its upper end surface is flush with the cavity forming surface of the movable mold 33. Further, if necessary, the lifting and lowering operations of the lifting pins 38A and 38B are repeated while the injection operation of the synthetic resin 40 from the gate 36A is continued before the holding pressure is completed. Also good. As a result, the alignment line and the like are surely not visible from the outside of the synthetic resin molded product.

  The synthetic resin molded products manufactured in the first to seventh embodiments described above contain the different materials 19, 29, 39 for improving the appearance quality and the like, and have openings such as holes. Nevertheless, the orientation lines 17A2, 27A2, 27B2, 37A2, and 37B2 can be made invisible as much as possible from the outside, and the appearance can be satisfactorily finished.

  In the first to seventh embodiments, the movable molds 13, 23, 33 are provided with the opening forming bodies 15, 25A, 25B, 35A, 35B for forming openings in the synthetic resin molded product. Although it is embodiment, not only the said opening formation body, but the thin-walled formation body which forms a thin part in the said synthetic resin molded product, and the convex part formation groove | channel which forms a convex part in the said synthetic resin molded product are said movable molds Alternatively, the present invention can be similarly applied to the case where it is provided (or formed) in the fixed mold, and the structure thereof will be briefly described below.

  That is, as shown in FIG. 17, a convex forming groove 45A for screw mounting, for example, is formed on the cavity forming surface of the movable mold 43 which is a lower mold. The convex portion forming groove 45A is formed of a hollow cylindrical groove, and is for forming a convex portion having a screw mounting hole on the back surface of the synthetic resin molded product. Moreover, it is good also as a simple cylindrical groove | channel which is not hollow but forms a convex part in the said synthetic resin molded product. Further, a thin-walled body 45B for forming a recess on the back surface of the synthetic resin molded product is provided so as to protrude into the cavity 44 on the cavity forming surface of the movable mold 43. The thin-walled body 45B has, for example, a quadrangular pyramid shape, and has a height that does not reach the cavity forming surface of the fixed mold 42 that is the upper mold when the mold is closed. Furthermore, a convex portion forming groove 45C for forming a reinforcing rib is formed on the back surface of the synthetic resin molded product. The convex portion forming groove 45 </ b> C is a long and narrow groove formed on the cavity forming surface of the movable mold 43, for example, having a square shape in plan view. Reference numeral 45D denotes an opening forming body that forms an opening in the synthetic resin molded product, and reference numeral 41 denotes a medium passage that performs the same function as the medium passage 11.

  Further, as shown in FIG. 18, for example, a protrusion-forming groove 55 </ b> A for screw attachment is formed on the cavity forming surface of the fixed mold 52 that is an upper mold. The convex portion forming groove 55A is formed of a hollow cylindrical groove, and is for forming a convex portion having a screw mounting hole on the surface of the synthetic resin molded product. Moreover, it is good also as a simple cylindrical groove | channel which is not hollow but forms a convex part in the said synthetic resin molded product. Further, a thin-walled forming body 55B for forming a recess on the surface of the synthetic resin molded product is provided so as to protrude into the cavity 54 on the cavity forming surface of the fixed mold 52. The thin formed body 55B has, for example, a quadrangular pyramid shape, and has a height that does not reach the cavity forming surface of the movable mold 52 that is the lower mold when the mold is closed. Further, a convex forming groove 55C for forming a reinforcing rib is formed on the surface of the synthetic resin molded product. The convex portion forming groove 55C is a long and narrow groove formed on the cavity forming surface of the fixed mold 52, for example, having a square shape in plan view. Reference numeral 55D denotes an opening forming body that forms an opening in the synthetic resin molded product, and is provided so as to protrude into the cavity 54 so as to come into contact with the cavity forming surface of the movable mold 43 when the mold is closed. A medium passage 51 performs the same function as the medium passage 11.

  The number of gates in the first to seventh embodiments is not limited to the number shown in the drawings, and may be two or more or three or more. In this case, if each gate performs the same function as each gate in each of the first to seventh embodiments, even if the number of each gate is two or more or three or more, they are the same as those in the first to seventh embodiments. Should be treated as each gate. That is, the object of the present invention is in the synthetic resin molded product, on the back of the orientation line formed by injection of the synthetic resin containing different materials, each opening forming body, each thin forming body, and each convex forming groove as viewed from the gate side. This is to make each formed alignment line as invisible as possible from the outside, and the number of each gate is not limited.

  Accordingly, in particular corresponding to each opening formation body in the first to seventh embodiments, a gate that injects molten synthetic resin into the cavity and forms each alignment line behind each opening formation body is the first gate. A gate that injects the synthetic resin into the cavity so as to make each alignment line formed on the first gate invisible as much as possible from the outside of the synthetic resin molded product. 2 gates (other gates).

  Further, in all the embodiments described above, when each gate is opened, the molten synthetic resin is injected into the cavity, and conversely, when each gate is closed, the molten synthetic resin is injected into the cavity. Stop. However, a configuration may be adopted in which injection of the synthetic resin into the cavity is started or stopped by opening and closing the injection path of the synthetic resin upstream of the gate.

  Moreover, the shape of each opening formation body and each raising / lowering pin in the above 1st-7th embodiment is not restricted to the shape represented in each drawing, The drive mechanism which raises / lowers each raising / lowering pin is also the mechanism of the mechanism. The configuration does not matter. Also in the embodiment as shown in FIG. 17, the necessary lifting pins are provided in the movable mold 43 corresponding to the convex forming grooves 45A, the thin-walled forming bodies 45B, the convex forming grooves 45C, and the opening forming bodies 45D. May be provided. Also in the embodiment as shown in FIG. 18, necessary lifting pins are attached to the fixed metal plate corresponding to the convex forming groove 55A, the thin-walled forming body 55B, the convex forming groove 55C, and the opening forming body 55D. The mold 52 may be provided.

  Furthermore, the second predetermined temperature described above in the first to seventh embodiments is, for example, a temperature equivalent to a molten thermoplastic synthetic resin injected from each gate. Any temperature within the range from the softening point temperature of the synthetic resin at which the surface layer portion of the resin (the portion near the cavity forming surface of the fixed mold) easily flows to a temperature at which the characteristics of the synthetic resin can be maintained can be used. .

  By passing a heating medium or a cooling medium through the medium passages 11, 21, 31, 41, 51 in all the above embodiments, the fixed molds 12, 22, 32, Heating or cooling the cavities forming surfaces of 42 and 52, but heating only by passing a cooling medium through the medium passages 11, 21, 31, 41 and 51, and heating with an electric heater or the like. A means may be embedded in the fixed mold 12, 22, 32, 42, 52 along the cavity.

  As described above, the embodiment of the present invention has been described. However, various alternatives, modifications, and variations can be made by those skilled in the art based on the above description, and the present invention is not limited to the various embodiments described above without departing from the spirit of the present invention. Including alternatives, modifications or variations.

12, 22, 32, 42, 52 Fixed mold 13, 23, 33, 43, 53 Movable mold 14, 24, 34, 44, 54 Cavity 15, 25A, 25B, 35A, 35B, 45D, 55D Opening formation body 16 First gate 18 Second gate 26A, 36 Gate 26B, 36A Other gates 19, 29, 39 Dissimilar materials 20, 30, 40 Synthetic resin 28A, 28B, 38A, 38B, 38C Lifting pins 45A, 45C, 55A, 55C Convex Part forming grooves 45B, 55B Thin-walled formed bodies S1, S2 spaces P1, P2 pool spaces U1-U4

Claims (4)

An injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A gate for injecting the synthetic resin into the cavity;
As seen from the gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the convex forming groove behind the opening forming body, the thin-walled forming body, or the convex forming groove and is formed by joining together. The movable mold near the weld line is provided with an elevating pin provided so as to be movable up and down in the cavity,
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, After the synthetic resin is injected from the gate and the injection line is formed on the back side of the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the gate side by the injection , and Before completion of the holding pressure for increasing the compression density of the synthetic resin in the cavity, the upper end surface of the synthetic resin is movable when the injection of the synthetic resin from the gate is started while continuing the injection of the synthetic resin from the gate. after entering into the cavity from a state which existed same flush with the cavity of the mold forming surface is raised the lifting pins, morphism wherein the lowering to return to the original position Molding apparatus. An injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A first gate for injecting the synthetic resin into the cavity;
The synthetic resin is injected from the first gate and intersects the alignment line of the different material formed behind the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the first gate side. A second gate for injecting the synthetic resin;
When viewed from the first gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the convex forming groove behind the opening forming body, the thin-walled forming body, or the convex forming groove and joins each other. An elevating pin provided in the cavity so as to be movable up and down is provided in the movable mold near the weld line formed by
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, After the synthetic resin is injected from the first gate and the alignment line is formed by the injection, and before the holding pressure for increasing the compression density of the synthetic resin in the cavity is completed, the first gate From the state where the upper end surface of the synthetic resin is flush with the cavity forming surface of the movable mold at the start of injection, the lifting pin is lifted to enter the cavity and then returned to the original position. The injection molding apparatus characterized in that the first gate is closed and the second gate is opened so as to inject the synthetic resin . An injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A gate for injecting the synthetic resin into the cavity;
As seen from the gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the convex forming groove behind the opening forming body, the thin-walled forming body, or the convex forming groove and is formed by joining together. A first elevating pin provided to be movable up and down in the movable mold in the vicinity of the weld line
A second lifting pin provided to be movable up and down in the movable mold so as to sandwich the weld line with the first lifting pin;
At the start of injection of the synthetic resin by the gate, the first lifting pin has its upper end surface flush with the cavity surface of the mold, and the second lifting pin has its upper end surface flush with the movable mold. The synthetic resin pool space is formed above the second elevating pin as a position below the cavity forming surface,
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, The synthetic resin is injected from the gate , and after the formation of the alignment line of the different material on the back of the opening forming body, the thin forming body, or the convex forming groove as viewed from the gate side by the injection, and the Before the pressure holding to increase the compression density of the synthetic resin in the cavity was completed, the gate was opened and the injection of the synthetic resin was continued, and the first lifting pin was raised to enter the cavity. after the upper end face is lowered so as to have the same flush with the cavity forming surface of the movable mold, and at the same time as the lowering of the first lifting pin, or before or after this descent, the upper end surface of front Injection molding apparatus, characterized in that push the synthetic resin by raising the second lift pins so as to have the same flush with the cavity-forming surface of the movable mold pooled in the reservoir space in the cavity . An injection molding apparatus for injecting and molding a molten thermoplastic synthetic resin containing a different material in a cavity formed between a fixed mold and a movable mold,
An opening forming body that forms an opening in the molded product, a thin-walled forming body that forms a thin portion in the molded product, or a convex forming groove that forms a convex portion in the molded product is provided in the movable mold or the fixed mold. With
Heating means for heating the cavity forming surface of the fixed mold;
A first gate for injecting the synthetic resin into the cavity;
The synthetic resin is injected from the first gate and intersects the alignment line of the different material formed behind the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the first gate side. A second gate for injecting the synthetic resin;
When viewed from the first gate side, the synthetic resin wraps around the opening forming body, the thin-walled forming body, or the protruding portion forming groove behind the opening forming body, the thin-walled forming body, or the protruding portion forming groove, and joins each other. A first elevating pin provided to be movable up and down in the movable mold in the vicinity of the weld line formed by
A second lifting pin provided to be movable up and down in the movable mold so as to sandwich the weld line with the first lifting pin;
At the start of injection of the synthetic resin by the first gate, the first lifting pin has its upper end surface flush with the cavity surface of the mold, and the second lifting pin has its upper end surface flush with the movable metal The synthetic resin pool space is formed above the second lift pins as a position below the cavity forming surface of the mold,
Under a state where the cavity forming surface of the fixed mold is heated by the heating means to a predetermined temperature within a range from the softening point temperature of the synthetic resin to a temperature at which the characteristics of the synthetic resin can be maintained, After the synthetic resin is injected from the first gate and the alignment line is formed behind the opening forming body, the thin-walled forming body, or the convex forming groove as viewed from the first gate side by the injection. And before the pressure holding to increase the compression density of the synthetic resin in the cavity is completed, the first gate is closed and the second gate is opened to start the injection of the synthetic resin, or before and after the start. Then, after the first elevating pin is raised and entered into the cavity, the upper end surface thereof is lowered so as to be flush with the cavity forming surface of the movable mold, and the first Simultaneously with lowering of the lift pins, or before or after this descent, the space reservoir wherein the upper end face is raised the second lift pins so as to have the same flush with the cavity forming surface of the movable mold An injection molding apparatus, wherein the stored synthetic resin is pushed up into the cavity.