JP6846637B2 - Manufacturing method of resin molded products - Google Patents

Description

The present invention relates to a method for producing a hollow resin molded product such as a drain pipe.

For example, as a hollow resin molded product such as a drain pipe, a product formed by blow molding is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2007-138498

By the way, in a drainage pipe, it is studied to form a desired texture (texture, roughness, unevenness, etc.) on the inner surface of the flow path in order to control the flow of drainage. However, when the drain pipe is formed by blow molding, forming a desired texture on the inner surface of the flow path involves executing a process dedicated to texture formation after blow molding, which lengthens the entire manufacturing process. Further, depending on the shape of the drain pipe, it may be difficult to form a desired texture on the inner surface of the flow path after blow molding.

Therefore, an object of the present invention is to provide a method for producing a resin molded product capable of reliably forming a desired texture on the inner surface of the hollow resin molded product without executing a process dedicated to texture formation. ..

In order to achieve the above object, the method for producing a resin molded product according to one aspect of the present invention is a resin molding method for molding a resin molded product having a hollow portion by joining a first divided body and a second divided body. A molding step of manufacturing a product, in which a resin material is first injected into a space formed by a first mold and a second mold, and a first divided body and a second divided body are individually molded. With the first mold holding the first divided body and the second mold holding the second divided body, the first and second divided bodies and the second divided body are moved by relative movement of the first mold and the second mold. In the molding step in the first mold, including a moving step of bringing the joint edges of the divided body close to each other and a joining step of joining the joint edges of the first divided body and the second divided body. At least one of the region corresponding to the second divided body and the region corresponding to the first divided body in the molding step in the second mold is provided with a texture molding portion for molding the texture of the inner surface of the resin molded product. ing. A recess is formed as a joint edge in the first divided body, a joint protrusion is formed as a joint edge in the second divided body, and a rib is formed at an end portion of the joint protrusion in contact with the recess. In the joining step, the joining protrusion formed in the second divided body is inserted halfway through the recess formed in the first divided body, and the resin material is secondarily injected into the remaining space of the recess to perform the first division. The joint edges of the body and the second divided body are joined to each other.

According to the method for producing a resin molded product according to one aspect of the present invention, a desired texture can be reliably formed on the inner surface of the hollow resin molded product without executing a step dedicated to texture formation.

FIG. 1 is a front view showing a schematic configuration of a drainage pipe according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the drainage pipe of the same as above. FIG. 3 is an enlarged cross-sectional view showing the inner surface shapes of the first and second divided bodies of the drainage pipe of the above. FIG. 4 is a cross-sectional view showing a mold according to the first embodiment and in an opened state. FIG. 5 is a cross-sectional view showing a mold of the same as above, which is closed at the time of primary injection. FIG. 6 is an enlarged cross-sectional view showing a region forming the internal shape of the first divided body in the first core portion according to the first embodiment. FIG. 7 is a cross-sectional view showing a state of the mold during the molding process according to the first embodiment. FIG. 8 is a cross-sectional view showing a state of the mold at the time of the moving step according to the first embodiment. FIG. 9 is a cross-sectional view showing a state of the mold at the time of the joining process according to the first embodiment. FIG. 10 is a cross-sectional view of the drainage pipe according to the second embodiment. FIG. 11 is an enlarged cross-sectional view showing a part of the drainage pipe before the secondary injection according to the second embodiment in an enlarged manner. FIG. 12 is an enlarged cross-sectional view showing a part of the drainage pipe before the secondary injection according to the second embodiment in an enlarged manner. FIG. 13 is a cross-sectional view of the first divided body and the second divided body at the time of the moving step according to the third embodiment. FIG. 14 is a cross-sectional view of the first divided body and the second divided body after the moving step according to the third embodiment and before the secondary injection. FIG. 15 is an enlarged cross-sectional view showing a part of the first divided body and the second divided body after the moving step according to the third embodiment and before the secondary injection. FIG. 16 is an enlarged cross-sectional view showing a part of the first divided body, the second divided body, and the resin material after the secondary injection in the joining step according to the third embodiment. FIG. 17 is an enlarged cross-sectional view showing a part of the first divided body, the second divided body, and the resin material after the secondary injection in the joining step according to the comparative example.

Hereinafter, a method for producing a resin molded product according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, all of the embodiments described below show a preferable specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement and connection forms of components, processes, order of steps, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Therefore, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept of the present invention will be described as arbitrary components.

Further, each figure is a schematic view and is not necessarily exactly illustrated. Further, in each figure, the same components are designated by the same reference numerals.

(First Embodiment)
Hereinafter, the method for producing the resin molded product according to the first embodiment will be described with reference to FIGS. 1 to 9.

[Resin molded product]
First, an example of a resin molded product molded by the method for producing a resin molded product according to the first embodiment will be described. Here, a resin drainage pipe will be described as an example of a resin molded product. The resin molded product is not limited to the drain pipe, and may be a resin molded product having a hollow portion.

FIG. 1 is a front view showing a schematic configuration of a drainage pipe according to the first embodiment. FIG. 2 is a cross-sectional view of the drainage pipe according to the first embodiment. Specifically, FIG. 2 is a cross-sectional view seen from the II-II cut surface in FIG.

As shown in FIGS. 1 and 2, the drain pipe 10 is, for example, an S-shaped trap having an S-shaped flow path 11 as a hollow portion. Here, the S-shaped trap will be described as an example of the drainage pipe 10, but a P-shaped drainage pipe other than the S-shaped trap may be used.

The drainage pipe 10 has an inflow port 12 formed in the upper part and an outflow port 13 formed in the lower part, and an S-shaped flow path 11 is formed so as to communicate the inflow port 12 and the outflow port 13. .. The drainage pipe 10 is integrally formed of a resin material, but at the time of manufacture, it is divided into a first divided body 21 and a second divided body 22, and these first divided bodies 21 and By joining the second divided body 22 at the joining portion 23, the entire drainage pipe 10 is integrated.

The first divided body 21 is a portion forming the upper half of the drainage pipe 10 in FIG. The first divided body 21 is formed with a first groove portion 211 having an S-shape in front view forming a flow path 11. A recess 213 is formed in the joint edge 212 of the first divided body 21 with the second divided body 22. The recess 213 is formed along the outer surface of the first divided body 21, and the joint portion 23 is provided in the recess 213.

The second divided body 22 is a portion forming the lower half of the drainage pipe 10 in FIG. The second divided body 22 is formed with a second groove portion 221 having an S-shape in front view forming a flow path 11. A recess 223 is formed in the joint edge 222 of the second divided body 22 with the first divided body 21. The recess 223 is formed along the outer surface of the second divided body 22, and the joint portion 23 is provided in the recess 223.

By joining the first divided body 21 and the second divided body 22, the first groove portion 211 and the second groove portion 221 form a flow path 11. The flow path 11 has a first straight line portion 111, a second straight line portion 112, a third straight line portion 113, a first bent portion 114, and a second bent portion 115. The first straight line portion 111, the second straight line portion 112, and the third straight line portion 113 are arranged in parallel. The first bent portion 114 and the second bent portion 115 are bent in a U shape.

Hereinafter, with reference to the flow of drainage passing through the drainage pipe 10, the upstream side will be described as the base end portion and the downstream side as the tip end portion. The base end portion of the first straight line portion 111 is continuous with the inflow port 12. The tip end portion of the first straight line portion 111 and the base end portion of the first bent portion 114 are continuous. The tip end of the first bent portion 114 and the base end portion of the second straight line portion 112 are continuous. The tip end portion of the second straight line portion 112 and the base end portion of the second bent portion 115 are continuous. The tip end of the second bent portion 115 and the base end portion of the third straight line portion 113 are continuous. The tip of the third straight line portion 113 is continuous with the outlet 13.

Then, in the first divided body 21 and the second divided body 22, first gaps 24 and 25 are formed between the outer walls of the first straight line portion 111 and the second straight line portion 112 facing each other by the first bent portion 114. Has been done. Further, in the first divided body 21 and the second divided body 22, second gaps 26 and 27 are formed between the outer walls of the second straight line portion 112 and the third straight line portion 113 facing each other by the second bent portion 115. Has been done. Joints 23 are provided in the first gaps 24 and 25 and the second gaps 26 and 27, respectively.

The joint portion 23 is a portion that is filled in the recesses 213 and 223 to join the first divided body 21 and the second divided body 22. The portion of the joint portion 23 corresponding to the first gaps 24 and 25 and the second gaps 26 and 27 is a rib 231 protruding from one outer wall of the opposing outer walls toward the other outer wall. Specifically, the rib 231 is connected to the outer walls of the first divided body 21 and the second divided body 22. The rib 231 may be separated from one outer wall or the other outer wall of the opposing outer walls. Further, in FIG. 1, the case where the ribs 231 are continuously formed along the longitudinal directions of the first gaps 24 and 25 and the second gaps 26 and 27, respectively, is shown, but it is intermittent. It may be formed as a target.

FIG. 3 is an enlarged cross-sectional view showing the inner surface shapes of the first divided body 21 and the second divided body 22 according to the first embodiment. Specifically, FIG. 3 shows an enlarged view of the inside of the alternate long and short dash lines C1 and C2 in FIG.

As shown in FIG. 3, the inner surface shape of the first divided body 21 and the second divided body 22, that is, the inner surface shape forming the flow path 11, is formed by intermittently patterning the concave portions 19 having a rectangular cross section. ing. As a result, irregularities are continuously formed on the inner surface of the flow path of the drain pipe 10. The unevenness constitutes the texture 18 on the inner surface of the flow path. The texture 18 shown in FIG. 3 is just an example of the texture, and the shape and size of the texture may be arbitrary. Further, the texture may be provided on the entire inner surface of the flow path or may be provided partially. A texture suitable for controlling the drainage flowing through the flow path 11 may be adopted.

[Mold]
Next, a mold for molding the drainage pipe 10 will be described.

FIG. 4 is a cross-sectional view showing a mold according to the first embodiment and in an opened state. FIG. 5 is a cross-sectional view showing a mold according to the first embodiment and a state in which the mold is closed at the time of primary injection.

As shown in FIGS. 4 and 5, the mold 300 is provided in a molding machine (not shown) that performs die slide injection molding (DSI molding), and the first mold 400 and the second mold 500 are combined. I have. The first mold 400 and the second mold 500 are formed of, for example, a metal material such as stainless steel.

The first mold 400 is a mold for molding a part of the first divided body 21 and a part of the second divided body 22. Specifically, in the first mold 400, a first cavity portion 410 for forming the outer shape of the first divided body 21, and a second cavity portion 410 for forming the internal shape and the recess 223 of the second divided body 22 are formed. One core portion 420 is provided. The first cavity portion 410 is formed with a recess corresponding to the external shape of the first divided body 21. The first core portion 420 is formed with a convex portion corresponding to the internal shape of the second divided body 22 and the concave portion 223.

The second mold 500 is a mold for molding a part of the first divided body 21 and a part of the second divided body 22. Specifically, the second mold 500 has a second core portion 510 for molding the internal shape of the first split body 21 and the recess 213, and a second core portion 510 for molding the outer shape of the second split body 22. Two cavity portions 520 are provided. The second cavity portion 520 is formed with a recess corresponding to the external shape of the second divided body 22. The second core portion 510 is formed with a convex portion corresponding to the internal shape of the first divided body 21 and the concave portion 213.

FIG. 6 is an enlarged cross-sectional view showing a region forming the internal shape of the second divided body 22 in the first core portion 420 according to the first embodiment. Note that FIG. 6 also shows the second divided body 22 formed by the first core portion 420.

As shown in FIG. 6, a texture forming portion 425 for forming the texture of the inner surface of the flow path is formed in the region of the first core portion 420 that forms the internal shape of the second divided body 22. The texture forming portion 425 has an uneven shape corresponding to the texture 18. That is, by forming the shape corresponding to the desired texture 18 in the texture forming portion 425, the desired texture 18 can be formed on the inner surface of the flow path of the drain pipe 10 only by injection molding.

A similar texture forming portion 425 is also provided in the region of the first core portion 420 that forms the internal shape of the second divided body 22.

As shown in FIG. 5, when the first mold 400 and the second mold 500 are closed before the primary injection, the first cavity portion 410 and the second core portion 510 are used for the first divided body 21. Cavity (space) 210 is formed, and the cavity (space) 220 for the second divided body 22 is formed by the second cavity portion 520 and the first core portion 420.

The first mold 400 is formed with a first molding gate 450 for injecting a resin material for primary injection into the cavity 220. The injection port of the first molding gate 450 is arranged at a position corresponding to the recess 223 of the second divided body 22 in the first core portion 420.

Further, the second mold 500 is formed with a second molding gate 550 for injecting a resin material for primary injection into the cavity 210. The injection port of the second molding gate 550 is arranged at a position corresponding to the recess 213 of the first divided body 21 in the second core portion 510.

As described above, the first molding gate 450 and the second molding gate 550 are gates for primary injection, and the injection ports are arranged at positions corresponding to the joint portions 23 formed by the recesses 213 and 223. ing.

Further, the second mold 500 is formed with a joining gate 560 for injecting a resin material for secondary injection. The joint gate 560 is a gate for secondary injection. The injection port of the joint gate 560 is arranged at a position corresponding to the rib 231 in the joint portion 23. Specifically, a plurality of joining gates 560 are provided so as to correspond to the ribs 231 formed in the gaps 25 and 27 of the second split body 22 (two are shown in FIG. 4 and the like).

Further, the molding machine includes an injection molding unit (not shown) that injects a resin material into the first molding gate 450, the second molding gate 550, and the joining gate 560, and the first mold 400 and the second mold. A first drive source for switching between mold closing and mold opening of the mold 500 (not shown) and a second drive source for sliding the second mold 500 with respect to the first mold 400 when the mold is opened (not shown). And are provided. The slide movement of the second mold 500 by the second drive source may be a straight movement or a rotational movement, but in the following description, the straight movement will be illustrated as an example.

Further, the molding machine includes a computer (control circuit) for controlling the operation of each device such as an injection molding unit, a first drive source, and a second drive source. The computer has, for example, a non-volatile memory in which the program is stored, a volatile memory which is a temporary storage area for executing the program, an input / output port, a processor for executing the program, and the like.

[motion]
Subsequently, a method for manufacturing the resin molded product according to the first embodiment will be described. In the description of this manufacturing method, the resin material before curing is shaded.

The method for manufacturing a resin molded product is performed by a computer of a molding machine executing a program to control the operation of each device such as an injection molding unit, a first drive source, and a second drive source.

First, during standby, as shown in FIG. 4, the first mold 400 and the second mold 500 are in a mold-opened state. Then, with the start of resin molding, the first mold 400 and the second mold 500 are closed as shown in FIG.

After closing the mold, the molding process is executed.

FIG. 7 is a cross-sectional view showing a state of the mold 300 at the time of the molding process according to the first embodiment. In FIG. 7, the resin material before curing is shaded.

As shown in FIG. 7, the resin material is primarily injected into the cavities 210 and 220 from the first molding gate 450 and the second molding gate 550, respectively. As a result, the first divided body 21 and the second divided body 22 are individually molded. At this time, the region corresponding to the second divided body 22 in the first mold 400 (first core portion 420) and the region corresponding to the first divided body 21 in the second mold 500 (second core portion 510) Since the texture forming portion 425 is formed, the texture 18 is formed on the inner surface of the flow path between the first divided body 21 and the second divided body 22 (see FIG. 6).

After the molding process, a moving process is performed.

FIG. 8 is a cross-sectional view showing a state of the mold 300 at the time of the moving step according to the first embodiment.

After the molding step, when the first divided body 21 and the second divided body 22 are cured, the first mold 400 and the second mold 500 are once opened, and then the second mold 500 is first. It slides with respect to the mold 400. Then, as shown in FIG. 8, the first mold 400 and the second mold 500 are closed again. The first divided body 21 is held in the first cavity portion 410 of the first mold 400 and the second cavity portion 520 of the second mold 500 is held between the time when the mold is opened and the time when the mold is closed again. The two-divided body 22 is held. Then, when the mold is closed, the joint edge 212 of the first divided body 21 and the joint edge 222 of the second divided body 22 come into close contact with each other.

At this time, a space S1 filled with the resin material for secondary injection is formed between the first mold 400, the second mold 500, the first divided body 21, and the second divided body 22.

After the moving step, a joining step is performed.

FIG. 9 is a cross-sectional view showing a state of the mold 300 at the time of the joining step according to the first embodiment.

As shown in FIG. 9, in the joining step, the resin material is secondarily injected from the joining gate 560 into the space S1. When the entire space S1 is filled with the resin material, the joint portion 23 is formed. By this joint portion 23, the joint edges 212 and 222 of the first division body 21 and the second division body 22 are joined to each other. The same resin material is used for the primary injection and the secondary injection. Examples of the resin material used in the primary injection and the secondary injection include thermoplastic materials such as PP (polypropylene) and ABS resin.

Then, when the joint portion 23 is cured after the joining step, the first mold 400 and the second mold 500 are opened, and the drain pipe 10 as shown in FIGS. 1 and 2 is taken out.

Before the resin material is secondarily injected into the space S1, the surface of the portion of the first divided body 21 and the second divided body 22 where the joint portion 23 is to be formed is surface-modified by plasma treatment or the like. Quality treatment may be applied. As a result, minute irregularities are formed on the surface. This unevenness exerts an anchor effect, and the bonding strength between the second-injected resin material and the first divided body 21 and the second divided body 22 can be improved.

(Second Embodiment)
Next, the drainage pipe according to the second embodiment will be described with reference to FIGS. 10 to 12.

FIG. 10 is a cross-sectional view of the drainage pipe according to the second embodiment. Specifically, FIG. 10 is a diagram corresponding to FIG. 2. In the following description, the same reference numerals may be given to the parts equivalent to the drainage pipe 10 according to the first embodiment, and the description thereof may be omitted.

As shown in FIG. 10, in the first divided body 21A and the second divided body 22A forming the drainage pipe 10A, the outer walls forming the flow path 11 (see FIG. 1) are formed without gaps. The first divided body 21A is provided with a wall portion 291 that divides the first straight portion 111 and the second straight portion 112, and a wall portion 292 that divides the second straight portion 112 and the third straight portion 113. ing. Similarly, the second divided body 22A includes a wall portion 293 that divides the first straight line portion 111 and the second straight line portion 112, and a wall portion 294 that divides the second straight line portion 112 and the third straight line portion 113. Is provided.

In cross-sectional view, the wall portions 291,292 of the first divided body 21A are formed lower than the wall portions 293 and 294 of the second divided body 22A. Then, the wall portion 291 of the first divided body 21A and the wall portion 293 of the second divided body 22A are joined, and the wall portion 292 of the first divided body 21A and the wall portion 294 of the second divided body 22A are joined. There is. As a result, the joining positions P of the wall portions 291, 292, 293, and 294 are positioned so as to be biased outward from the first divided body 21A.

Further, in the first divided body 21A and the second divided body 22A, joining projections 281, 228 protruding outward are formed on the outer peripheral edges excluding the inflow port 12 and the outflow port 13. By joining the joining protrusions 281, 228, the outer peripheral edges of the first split body 21A and the second split body 22A are integrated.

At the time of molding the first divided body 21A, it is preferable to provide a gate for primary injection at a position corresponding to at least one tip surface of the wall portion 291,292 of the first divided body 21A. On the other hand, at the time of molding the second divided body 22A, it is preferable to provide a gate for primary injection at a position corresponding to at least one tip surface of the wall portions 293 and 294 of the second divided body 22A. The arrow G1 in FIG. 10 exemplifies the gate position for the primary injection of the first divided body 21A, and the arrow G2 exemplifies the gate position for the primary injection of the second divided body 22A. The mold may be manufactured so that each gate is arranged at such a position.

FIG. 11 is an enlarged cross-sectional view showing a part of the drainage pipe 10A before the secondary injection according to the second embodiment in an enlarged manner. Specifically, FIG. 11 shows a contact state between the wall portion 291 of the first divided body 21A and the wall portion 293 of the second divided body 22A surrounded by the alternate long and short dash line L1 in FIG. Since the wall portion 292 of the first divided body 21A and the wall portion 294 of the second divided body 22A have the same structure, the description thereof will be omitted.

As shown in FIG. 11, the boundary between the wall portion 291 of the first divided body 21A and the wall portion 293 of the second divided body 22A is filled with a space having a circular shape in cross section over the entire length of the wall portions 291,293. Part 298 is formed. The first divided body 21A is formed with at least one gate portion 299 that penetrates to the filling portion 298. By filling the filling portion 298 with the resin material for secondary injection through the gate portion 299, the wall portion 291 of the first divided body 21A and the wall portion 293 of the second divided body 22A are joined. .. Here, as described above, since the joint position P of the wall portions 291,293 is a position biased toward the outside of the first divided body 21A, the total length of the gate portion 299 can be shortened. Therefore, even if the resin material passes through the gate portion 299, the filling portion 298 can be filled in a highly fluid state without cooling.

FIG. 12 is an enlarged cross-sectional view showing a part of the drainage pipe 10A before the secondary injection according to the second embodiment in an enlarged manner. Specifically, FIG. 12 shows an enlarged portion of the portion surrounded by the alternate long and short dash line L2 in FIG.

As shown in FIG. 12, the boundary between the joint protrusion 281 of the first division body 21A and the joint protrusion 282 of the second division body 22A is a space having a circular cross section over the entire length of the joint protrusion 281,282. A filling portion 288 is formed. Further, at least one gate portion 289 penetrating to the filling portion 288 is formed at the boundary between the joint protrusion 281 and the joint protrusion 282. The resin material for secondary injection is filled in the filling portion 288 through the gate portion 289, so that the joining protrusions 281,282 are joined to each other.

Further, at the boundary between the joint protrusion 281 and the joint protrusion 282, a fitting portion 285 is formed on the flow path 11 side of the filling portion 288. The fitting portion 285 includes a convex portion 285a formed on one of the first divided body 21A and the second divided body 22A, and a concave portion 285b formed on the other. In FIG. 12, the case where the convex portion 285a is formed in the second divided body 22A and the concave portion 285b is formed in the first divided body 21A is illustrated, but these may be reversed. The fitting portion 285 is continuously formed along the entire length of the filling portion 288. Even if the resin material tries to enter the flow path 11 side from the filling portion 288, the fitting portion 285 blocks it.

(Third Embodiment)
Next, the drainage pipe according to the third embodiment will be described with reference to FIGS. 13 to 17.

FIG. 13 is a cross-sectional view of a state in which the first divided body and the second divided body of the drain pipe according to the third embodiment are divided, and FIG. 14 is a cross-sectional view after the drain pipe moving step according to the third embodiment. It is a cross-sectional view before the joining process. Specifically, FIG. 14 is a diagram corresponding to FIG. 10 in the second embodiment. In the following description, the same reference numerals may be given to the parts equivalent to the drainage pipe 10A according to the second embodiment, and the description thereof may be omitted.

As shown in FIG. 13, in the first divided body 21B and the second divided body 22B forming the drainage pipe 10B, the outer walls forming the flow path 11 (see FIG. 1) are formed without gaps. The second divided body 22B is provided between the first straight line portion 111 and the second straight line portion 112 and between the second straight line portion 112 and the third straight line portion 113, and is a wall portion that divides the two. 295 and 295 are provided.

Further, although not particularly shown, the joining protrusions 281,282, the filling portion 288, the gate portion 289, and the fitting portion 285 (convex portion 285a, concave portion 285b) provided in the second embodiment are also provided in the drain pipe 10B in the same manner. Be done.

A recess 296 is formed in the first divided body 21B as a joint edge. The second split body 22B is provided with a joint protrusion 2950 to be inserted into the recess 296 as a joint edge. The joint protrusion 2950 is composed of a tip portion of a wall portion 295.

At the time of molding the first divided body 21B, it is preferable to provide a gate for primary injection on the inner wall surface of the recess 296 of the first divided body 21B. On the other hand, at the time of molding the second divided body 22B, it is often the case that a gate for primary injection is provided at a position corresponding to at least one tip surface of the wall portions 295 and 295 of the second divided body 22B. The mold may be manufactured so that each gate is arranged at such a position.

FIG. 15 is an enlarged cross-sectional view showing a part of FIG. 14 showing the drainage pipe 10B before the secondary injection according to the third embodiment.

As shown in FIG. 15, the joint projection 2950 of the second divided body 22B is inserted into the recess 296 of the first divided body 21B and the mold is closed by the moving step. The remaining space in the recess 296 into which the joint protrusion 2950 is inserted serves as a filling portion for the resin material for secondary injection. The first divided body 21B is formed with at least one gate portion (not shown) penetrating to the filling portion. A resin material for secondary injection is injected into the filling portion through the gate portion.

In the third embodiment, the rib 2951 is provided at the end of the joint protrusion 2950 in contact with the recess 296. In the joining step, the resin material for secondary injection is injected through the gate portion, and as shown in FIG. 16, the resin material 297 for secondary injection is filled in the filling portion, so that the first divided body is formed. The recess 296 of the 21B and the joint projection 2950 of the second divided body 22B are joined. At this time, since the joint protrusion 2950 has the rib 2951, the resin material 297 is prevented from protruding from the filling portion.

That is, when the joint protrusion 2950 does not have the rib 2951, as shown in FIG. 17, when the resin material 297 for secondary injection is filled in the filling portion, the pressure of the resin material 297 causes the inner wall surface of the recess 296 to be separated. It spreads to form a gap between the inner wall surface of the recess 296 and the outer surface of the joint projection 2950, and the resin material 297 passes through the gap and the excess resin material 2971 protrudes from the recess 296.

On the other hand, in the third embodiment, the filling portion is filled with the resin material 297 for secondary injection, and the pressure of the resin material 297 exerts a force for expanding the space between the inner wall surfaces of the recess 296 and a force for expanding the space between the ribs 2951. .. Therefore, it is difficult for a gap to be formed between the inner wall surface of the recess 296 and the outer surface of the joint projection 2950, and the resin material 297 is unlikely to protrude from the recess 296.

(Other)
Although the insert molding apparatus according to the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment.

For example, in the above embodiment, the joint portion 23 is formed by secondarily injecting a resin material onto the joint edges 212 and 222 of the first split body 21 and the second split body 22 in the joining step. The case where the joint edges 212 and 222 are joined to each other by molding is illustrated. However, in the joining step, the joining edges 212 and 222 may be joined by heat welding the joining edges 212 and 222 of the first divided body 21 and the second divided body 22, respectively. By adopting the so-called HP-DSI (hot plate DSI) in the joining process, secondary injection becomes unnecessary and the mold can be simplified.

Further, in the above embodiment, gaps (first gaps 24, 25, second gaps 26, 27) are formed between the outer walls of the flow paths 11 facing each other by the first bent portion 114 and the second bent portion 115. The drainage pipe 10 was illustrated and described. However, it may be a drainage pipe in which the outer walls are close to each other and there is no gap.

Further, in the above embodiment, the case where the resin material in the primary injection and the resin material in the secondary injection are the same is illustrated, but the resin material in the primary injection and the resin material in the secondary injection are used. It may be different. This makes it possible to increase the degree of freedom in selecting the resin material used in the primary injection or the secondary injection. In particular, it is also possible to individually select a resin material suitable for each of the characteristics of the primary injection and the secondary injection.

For example, in the secondary injection, since the resin material is poured into the space S1 whose cross-sectional area is narrower than the cavities 210 and 220, the fluidity of the resin material for the secondary injection is higher than that of the resin material for the primary injection. desired. In this case, a resin material having a higher fluidity than the resin material for the primary injection may be used for the secondary injection. If the fluidity of the resin material for secondary injection is increased, the resin material can be supplied to the entire space S1 even if the number of joint gates 560 installed is reduced.

It is also possible to add additives to the resin material. To increase the impact resistance, rubber, elastomer, etc. may be added to the resin material. Further, in order to increase the joint strength, a strength-specialized grade material (filler) may be added to the resin material for secondary injection.

Further, a resin material that does not easily get oiled, such as an acrylic resin, may be used.

In addition, there are also forms obtained by applying various modifications to each embodiment that can be conceived by those skilled in the art, and forms realized by arbitrarily combining the components and functions of each embodiment without departing from the spirit of the present invention. Included in the present invention.

As is clear from the first to third embodiments described above and the modified examples thereof, in the method for producing the resin molded product of the first embodiment, the first divided body 21 and the second divided body 22 are joined. This is a method for manufacturing a resin molded product that forms a drain pipe 10 having a flow path 11. This manufacturing method includes a molding step, a moving step, and a joining step. In the molding step, the resin material is first injected into the cavities 210 and 220 formed by the first mold 400 and the second mold 500, and the first divided body 21 and the second divided body 22 are individually molded. In the moving step, the first mold 400 and the second mold 500 are held in a state where the first mold 400 holds the first divided body 21 and the second mold 500 holds the second divided body 22. The joint edges 212 and 222 of the first divided body 21 and the second divided body 22 are brought close to each other by relative movement. In the joining step, the joining edges 212 and 222 of the first split body 21 and the second split body 22 are joined to each other. At least one of the first core portion 420 in the first mold 400 and the second core portion 510 in the second mold 500 is provided with a texture forming portion 425 for forming the texture 18 on the inner surface of the flow path.

According to the first aspect, since the texture forming portion 425 is provided on at least one of the first core portion 420 of the first mold 400 and the second core portion 510 of the second mold 500, the first When the split body 21 and the second split body 22 are molded by the primary injection, the texture 18 can also be molded at the same time. Therefore, the desired texture 18 can be reliably formed on the inner surface of the flow path of the drainage pipe 10 without executing the step dedicated to texture formation.

In addition to molding the texture 18 by the texture forming portion 425, after joining the first divided body 21 and the second divided body 22, a plasma generating electrode is inserted inside the texture forming electrode to perform plasma treatment, and the surface is modified. The texture may be formed on the inner surface of the first divided body 21 and the second divided body 22.

The second aspect is realized in combination with the first aspect. In the second aspect, in the joining step, the joining edges 212, 222 are formed by secondarily injecting a resin material onto the joining edges 212, 222 of the first divided body 21 and the second divided body 22, respectively. They are joining each other.

According to the second aspect, the desired texture 18 can be reliably formed even when the first divided body 21 and the second divided body 22 are integrated by secondary injection of the resin material. ..

The third aspect is realized in combination with the second aspect. In the third aspect, the recess 296 is formed as the joint edge in the first divided body 21 (21B), and the joint protrusion 2950 is formed as the joint edge in the second divided body 22 (22B), and the joining step is performed. Then, the joint projection 2950 formed in the second divided body 22 is inserted halfway through the concave portion 296 formed in the first divided body 21, and the resin material is secondarily injected into the remaining space of the concave portion 296. The joint edges are joined to each other, and a rib 2951 is provided at an end of the joint protrusion 2950 in contact with the recess 296.

According to the third aspect, the pressure of the resin material 297 exerts a force for expanding between the ribs 2951 in addition to a force for expanding the inner wall surface of the recess 296. Therefore, it is difficult for a gap to be formed between the inner wall surface of the recess 296 and the outer surface of the joint projection 2950, and the resin material 297 is unlikely to protrude from the recess 296.

The fourth aspect is realized in combination with the second or third aspect. In the fourth aspect, the resin material in the primary injection and the resin material in the secondary injection are the same.

According to the fourth aspect, since the same resin material is used for the primary injection and the secondary injection, it is possible to increase the joint strength between the first divided body 21 and the second divided body 22 and the joint portion 23. it can. Further, since the same resin material can be used, it is possible to make the injection molding part of the primary injection and the secondary injection common.

The fifth aspect is realized in combination with the second or third aspect. In the fourth aspect, the resin material in the primary injection and the resin material in the secondary injection are different.

According to the fifth aspect, since different resin materials are used for the primary injection and the secondary injection, the degree of freedom in selecting the resin material used in the primary injection and the secondary injection can be increased.

The sixth aspect is realized by the combination with the first to fifth aspects. In the sixth aspect, the resin molded product is a drainage pipe 10 having a hollow portion as a flow path 11. According to the sixth aspect, the texture 18 can be reliably formed even when the drainage pipe 10 is manufactured.

The seventh aspect is realized in combination with the sixth aspect. In the seventh aspect, the flow path 11 has at least one bent portion (first bent portion 114 and second bent portion 115) bent in a U shape. According to the seventh aspect, the texture 18 can be reliably formed even when the drainage pipe 10 having two bent portions such as an S-shaped trap is manufactured.

The eighth aspect is realized in combination with the seventh aspect. In the eighth aspect, gaps (first gaps 24 and 25, second gaps 26 and 27) are formed between the outer walls of the flow paths 11 facing each other by the bent portion. According to the eighth aspect, the first molding gate 450, the second molding gate 550, and the joining gate 560 can be formed at locations corresponding to the gaps.

The ninth aspect is realized in combination with the eighth aspect. In the ninth aspect, ribs 231 protruding from one outer wall of the outer walls toward the other outer wall are formed in the first gaps 24 and 25 and the second gaps 26 and 27 of the drainage pipe 10. According to the ninth aspect, the rib 231 reinforces the drain pipe 10, and the rigidity can be increased.

The tenth aspect is realized in combination with the ninth aspect. In a tenth aspect, the ribs 231 are connected to the outer walls. According to the tenth aspect, since the ribs 231 are connected to the outer walls, the ribs 231 are hung between the first gaps 24 and 25 and the second gaps 26 and 27. Therefore, the rigidity of the entire drainage pipe 10 can be further increased.

The eleventh aspect is realized in combination with the tenth aspect. In the eleventh aspect, the rib 231 is formed by secondary injection. According to the eleventh aspect, when the first divided body 21 and the second divided body 22 are integrated by the secondary injection, the rib 231 can be formed at the same time.

The twelfth aspect is realized by the combination with the ninth to eleventh aspects. In the twelfth aspect, the first molding gate 450 and the second molding gate 550, which are gates for primary injection, are provided at positions corresponding to the ribs 231. According to the twelfth aspect, the second molding gate 550 can be arranged in the vicinity of the cavity 210 for the first split body 21, and the first molding gate can be arranged in the vicinity of the cavity 220 for the second split body 22. 450 can be placed. Therefore, the filling balance of the resin material for each of the cavities 210 and 220 can be improved, and the first divided body 21 and the second divided body 22 can be uniformly molded.

The thirteenth aspect is realized in combination with the ninth to twelfth aspects. In the thirteenth aspect, the joining gate 560, which is a gate for secondary injection, is provided at a position corresponding to the rib 231. According to the thirteenth aspect, the filling balance at the time of molding the joint portion 23 can be improved, and the entire drainage pipe 10 can be uniformly molded.

In the fourteenth aspect, it is realized in combination with the first aspect. In the fourteenth aspect, in the joining step, the joining edges of the first split body 21 and the second split body 22 are joined to each other by heat welding.

According to the fourteenth aspect, the secondary injection becomes unnecessary, and the mold 300 can be simplified.

10 Drain pipe 11 Flow path 114 1st bending part 115 2nd bending part 18 Texture 21 1st division 21B 1st division 210 Cavity 212 Joint edge 22 2nd division 22B 2nd division 220 Cavity 222 Joint edge 231 rib 24 1st gap 25 1st gap 26 2nd gap 27 2nd gap 2950 Joint protrusion 2951 Rib 296 Recessed 400 1st mold 420 1st core part 425 Texture molding part 450 1st molding gate 500 2nd mold 510 2 core part 550 2nd molding gate 560 Joining gate

Claims (11)

A method for manufacturing a resin molded product, which forms a resin molded product having a hollow portion by joining the first divided body and the second divided body.
A molding process in which a resin material is first injected into a space formed by a first mold and a second mold to individually mold the first divided body and the second divided body.
With the first mold holding the first divided body and the second mold holding the second divided body, the relative movement of the first mold and the second mold causes the said. A moving step of bringing the joint edges of the first divided body and the second divided body close to each other,
Including a joining step of joining the joining edges of the first divided body and the second divided body to each other.
At least one of the region corresponding to the second divided body in the molding step in the first mold and the region corresponding to the first divided body in the molding step in the second mold is described as described above. A texture molding part for molding the texture of the inner surface of the resin molded product is provided .
A recess is formed in the first divided body as the joint edge.
A joint protrusion is formed on the second divided body as the joint edge, and a rib is formed at an end of the joint protrusion in contact with the recess.
In the joining step, the joining protrusion formed in the second split body is inserted halfway through the recess formed in the first split body, and the resin material is secondarily injected into the remaining space of the recess. A method for producing a resin molded product, which joins the joint edges of the first divided body and the second divided body. The method for producing a resin molded product according to claim 1 , wherein the resin material in the primary injection and the resin material in the secondary injection are the same. The primary and the resin material at the exit, method for producing a resin molded article according to claim 1 in which the resin material is different in the secondary injection. The method for producing a resin molded product according to any one of claims 1 to 3, wherein the resin molded product is a drainage pipe in which the hollow portion serves as a flow path. The method for producing a resin molded product according to claim 4 , wherein the flow path has at least one bent portion bent in a U shape. The method for producing a resin molded product according to claim 5 , wherein a gap is formed between the outer walls of the flow paths facing each other by the bent portion. The method for producing a resin molded product according to claim 6, wherein ribs protruding from one outer wall of the outer walls toward the other outer wall are formed in the gap of the drain pipe. The method for manufacturing a resin molded product according to claim 7, wherein the rib is connected to the outer walls. The method for producing a resin molded product according to claim 8, wherein the ribs are formed by the secondary injection. The method for manufacturing a resin molded product according to any one of claims 7 to 9 , wherein the gate for primary injection is provided at a position corresponding to the rib. The method for manufacturing a resin molded product according to any one of claims 7 to 10 , wherein the gate for secondary injection is provided at a position corresponding to the rib .

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