U-shaped gutter manufacturing method

Abstract

To provide a method for manufacturing an U-shaped groove that can form a space-saving and highly accurate U-shaped groove.SOLUTION: A method for manufacturing an U-shaped groove 100 includes a pre-U-shaped groove forming step and a bottom facing surface removing step. The pre-U-shaped groove forming step forms a pre-U-shaped groove 200. The pre-U-shaped groove 200 has a bottom portion 101, a left side wall 102, a right side wall 103, corner portions 104a and 104b, a bellows portion 110, and connecting portions 120a and 120b in the U-shaped groove 100, respectively, in addition to these, has a bottom facing surface 201 formed into a cylindrical shape. In this case, a bellows-shaped facing surface 202 and connecting portion facing surfaces 203a and 203b are formed on the bottom facing surface 201, respectively. In the bottom facing surface removing step, the U-shaped groove 100 is obtained by cutting and removing the bottom facing surface 201 formed in the pre-U-shaped groove 200.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a U-shaped resin gutter that has a bottom through which water flows and two side walls that stand up from both ends of the bottom in the width direction, and is open above the bottom. [Background technology]

[0002] U-shaped gutters made of synthetic resin have traditionally been used as irrigation channels or drainage gutters for supplying water for civil engineering, agricultural, industrial, or drinking water works. U-shaped gutters have a bottom through which water flows and two side walls rising from both ends of the bottom in the width direction, with the top of the bottom open and having a U-shaped cross section. In this case, the U-shaped gutters have bellows sections formed by alternating mountain folds and valley folds on the bottom and two side walls.

[0003] As a method for manufacturing such a U-shaped groove, for example, Patent Document 1 listed below discloses a continuous blow molding method in which two or four U-shaped grooves are arranged opposite each other and connected in the axial direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-151677

[0005] However, the method for manufacturing U-shaped grooves described in Patent Document 1 requires extremely large-scale equipment to form two or four U-shaped grooves simultaneously and continuously, which poses a problem in that the environment in which the manufacturing equipment can be installed is limited.

[0006] The present invention has been made to address the above-mentioned problems, and its object is to provide a method for manufacturing a U-shaped groove that can form a U-shaped groove with high precision in a space-saving manner. Summary of the Invention

[0007] In order to achieve the above object, the present invention is characterized by a method for manufacturing a resin U-shaped channel having a bottom through which water flows and two side walls standing up from both ends of the bottom in the width direction, with the top of the bottom open, and in which bellows-like bellows portions formed by alternating mountain folds and valley folds are formed on at least a part of the bottom and two side walls of the U-shaped channel, and in addition to the bottom and two side walls, there are also two side walls directly connected to each other and facing the bottom. and does not constitute the U-shaped groove. A pre-U-shaped groove is provided with a bottom facing surface and the cross section of the U-shaped groove is formed into a substantially square cylindrical shape. Inside the mold A pre-U-shaped groove forming process; Removed from the mold and a bottom-facing surface removing step of removing the bottom-facing surface of the pre-U-shaped groove.

[0008] According to the features of the present invention, the U-shaped gutter manufacturing method can form a U-shaped gutter with a cross-sectional shape that is approximately rectangular and cylindrical, with bottom-facing surfaces directly connected to the two side walls and facing the bottom. This allows the U-shaped gutter to be formed with a small depth. In this case, workers can immediately perform the bottom-facing surface removal process on the pre-U-shaped gutter, which is a semi-finished U-shaped gutter formed from a cylindrical body in the pre-U-shaped gutter forming process. However, because this pre-U-shaped gutter is formed as a cylindrical body, it can be stored or transported in a space-saving manner while suppressing changes in shape over time. When a U-shaped gutter is needed, the bottom-facing surface removal process can be performed at the factory or construction site. As a result, the U-shaped gutter manufacturing method of the present invention allows for the formation of a U-shaped gutter with high precision in a space-saving manner.

[0009] Another feature of the present invention is that in the manufacturing method of the U-shaped groove, The pre-U-shaped groove forming process is a process of forming a pre-U-shaped groove with both ends closed by bag portions.

[0010] Another feature of the present invention is that in the method for manufacturing a U-shaped gutter, the bellows portion is formed so as to be able to bend in both the left-right and up-down directions of the U-shaped gutter. According to the feature of the present invention configured in this way, the method for manufacturing a U-shaped gutter can form a space-saving, highly accurate U-shaped gutter even for a U-shaped gutter with low stiffness in which the bellows portion is formed so as to be able to bend in both the left-right and up-down directions of the U-shaped gutter.

[0011] Another feature of the present invention is that in the method for manufacturing the U-shaped gutter, the pre-U-shaped gutter molding process forms a bellows-like opposing surface on the bottom opposing surface that is continuously connected to the bellows portions formed on each of the two side walls.

[0012] According to the features of the present invention configured as described above, the method for manufacturing a U-shaped gutter forms a bellows-like opposing surface on the bottom opposing surface that is continuously connected to the bellows portions formed on each of the two side walls during the pre-U-shaped gutter molding process. Therefore, no matter where on the bellows-like opposing surface the bottom opposing surface is removed when removing it, a bellows portion that is continuously connected to the side walls can be ensured, and a U-shaped gutter with a bellows portion of any length can be formed. Furthermore, according to the present invention, there is no top or bottom in a pre-U-shaped gutter made of a cylindrical body, and the original bottom can be used as the bottom opposing surface, so the bottom or bottom opposing surface on the side that was accurately molded can be used as the bottom, and the other can be removed as the bottom opposing surface.

[0013] Another feature of the present invention is that in the method for manufacturing the U-shaped gutter, the pre-U-shaped gutter molding process molds an inclined portion that extends in an inclined or curved shape at the corner between the two side walls and the bottom-facing surface, and the bottom-facing surface removal process removes the bottom-facing surface while leaving at least a portion of the inclined portion.

[0014] According to the features of the present invention configured in this manner, the method for manufacturing a U-shaped gutter involves forming an inclined portion that extends in an inclined or curved shape at the corner between the two side walls and the bottom opposing surface in the pre-U-shaped gutter forming process, and the bottom opposing surface removal process removes the bottom opposing surface while leaving at least a portion of the inclined portion intact, so that inwardly bent inclined portions are formed at the upper ends of the two side walls, thereby increasing the rigidity of the two side walls.

[0015] Another feature of the present invention is that in the method for manufacturing a U-shaped gutter, the bellows portion is formed so that the thickness of the valley fold portion is greater than the thickness of the mountain fold portion.

[0016] According to the features of the present invention configured as described above, the method for manufacturing a U-shaped gutter has a greater thickness at the valley folds than at the mountain folds, thereby improving durability against contact with water flowing through the cylindrical gutter and foreign matter contained in the water. Furthermore, according to the method for manufacturing a U-shaped gutter of the present invention, a thinner mountain fold is formed at the mountain folds than at the valley folds, improving the ease of bending the bellows portion of the U-shaped gutter in the left-right and up-down directions. In this case, it is preferable to form the bellows portion so that the thickness continuously decreases from each valley fold to each mountain fold on the two side walls.

[0017] Another feature of the present invention is that in the method for manufacturing a U-shaped gutter, the bottom of at least one of the two ends of the U-shaped gutter and the two side walls each extend in the direction of water flow to form connecting portions for connecting to other U-shaped gutters, and the pre-U-shaped gutter molding process forms connecting portion opposing surfaces on the bottom opposing surface that are continuously connected to the connecting portions formed on the two side walls, and the bottom opposing surface removal process removes the connecting portion opposing surfaces.

[0018] According to the features of the present invention configured in this manner, the method for manufacturing a U-shaped gutter forms the cross-sectional shape of the U-shaped gutter into an approximately square cylindrical body in the pre-U-shaped gutter molding process, with a connecting portion opposing surface that faces the bottom of the connecting portion provided at the end of the U-shaped gutter, so that the U-shaped gutter can be molded small in the depth direction, and a space-saving, highly accurate U-shaped gutter can be molded. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing the outline of the external configuration of a U-shaped gutter manufactured by a U-shaped gutter manufacturing method according to one embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a cross-sectional view of a bellows portion in the U-shaped groove shown in FIG. 1. [Figure 3] 2 is a partially enlarged cross-sectional view of the bellows portion of the U-shaped groove shown in FIG. 1. [Figure 4] 2 is a flowchart showing the steps of manufacturing the U-shaped groove shown in FIG. 1. [Figure 5] 5 is a perspective view showing the outline of the external configuration of the pre-U-shaped groove formed in the pre-U-shaped groove forming step shown in FIG. 4 with the bag portion removed. FIG. [Figure 6] (A) and (B) are schematic diagrams showing the processing state in the pre-U-shaped groove molding process shown in Figure 2, where (A) is a schematic diagram showing the state in which a parison is introduced between a pair of molding dies, and (B) is a schematic diagram showing the state in which the molding dies are closed and air blown after the parison is introduced. [Figure 7] 5 is a perspective view showing the outline of the external configuration of the pre-U-shaped groove formed in the pre-U-shaped groove forming step shown in FIG. 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of a U-shaped gutter manufacturing method according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the outline of the external configuration of a U-shaped gutter 100 manufactured by the U-shaped gutter manufacturing method according to the present invention. Note that the drawings referred to in this specification are schematic, with some components exaggerated to facilitate understanding of the present invention. For this reason, the dimensions and ratios between the components may differ.

[0021] (Configuration of U-shaped gutter 100) First, before explaining the method for manufacturing a U-shaped gutter according to the present invention, we will explain the U-shaped gutter 100 manufactured by this method. The U-shaped gutter 100 is a component that constitutes a waterway through which water flows, such as an irrigation channel that supplies water for civil engineering work, agriculture, industry, or drinking water, or a drainage gutter, and is made of a resin material such as polyethylene.

[0022] In this case, the resin material constituting the U-shaped gutter 100 can be, in addition to polyethylene, hard synthetic resins such as polyvinyl chloride, polypropylene, polyethylene terephthalate, polyamide, or fiber-reinforced resins made by adding glass fiber, carbon fiber, or organic fiber to resin materials such as unsaturated polyester. This U-shaped gutter 100 mainly consists of a bottom 101, a left side wall 102, and a right side wall 103 that are integrally formed.

[0023] Bottom 101 is a portion that supports water (not shown) flowing in U-shaped gutter 100 from below, and is composed of a horizontally extending band-like plate. Left side wall 102 and right side wall 103 are portions that support water flowing in U-shaped gutter 100 from the left and right sides, and are formed as walls that rise upward from both ends of bottom 101 in the width direction of U-shaped gutter 100. In this case, left side wall 102 and right side wall 103 are formed to a height that is equal to or greater than the height of water flowing in U-shaped gutter 100 (i.e., the water level).

[0024] Furthermore, the left side wall 102 and the right side wall 103 have inclined portions 102a, 103a formed at their upper end portions, each curved inward. As shown in Fig. 2, the inclined portions 102a, 103a are portions for preventing the left side wall 102 and the right side wall 103 from easily collapsing, and are formed so as to incline toward the inside of the U-shaped gutter 100. In this embodiment, the inclined portions 102a, 103a are formed by curved surfaces that curve in an arc toward the inside of the U-shaped gutter 100.

[0025] Corner portions 104a and 104b are formed between the bottom 101 and the left side wall 102, and between the bottom 101 and the right side wall 103. The corner portions 104a and 104b are portions that connect the left side wall 102 and the right side wall 103 to the bottom 101, respectively, and are formed of curved surfaces that maintain a bellows shape, which will be described later.

[0026] The bottom 101, left side wall 102, right side wall 103, and corners 104a, 104b are respectively formed with a bellows portion 110 and connecting portions 120a, 120b. The bellows portion 110 is a portion that enables bending of the U-shaped gutter 100 in the up, down, left, and right directions, and is formed in a bellows shape with alternating peaks 111 that are folded in a mountain shape and protrude outward from the U-shaped gutter 100, and valleys 112 that are folded in a mountain shape and protrude inward from the U-shaped gutter 100.

[0027] In this case, as shown in Fig. 3, the bellows portion 110 is formed so that the thickness increases from the top of the peak portion 111 toward the deepest portion of the valley portion 112. In other words, the bellows portion 110 has a thickness t 112 The thickness of the peak 111 is t 111 The bellows portion 110 configured in this manner is uniformly formed on the bottom portion 101, the left side wall 102, the right side wall 103, and the corner portions 104a and 104b between the connecting portion 120a and the connecting portion 120b of the U-shaped groove 100. The thickness t 111 and the thickness t of the valley portion 112 112 The thickness of the smallest part should be 0.5 mm or more and 2 mm or less, and the thickness of the largest part should be 2 mm or more and 5 mm or less.

[0028] The connecting portions 120a and 120b are portions for connecting another U-shaped groove 100 (not shown) to the U-shaped groove 100, and are formed at both ends of the U-shaped groove 100. More specifically, the connecting portions 120a and 120b are formed in the shape of a recessed groove inside the U-shaped groove 100 and are configured to have fitting portions 121a and 121b that protrude toward the outside of the U-shaped groove 100.

[0029] These fitting portions 121a, 121b are formed as grooves that extend continuously between the left side wall 102 and the right side wall 103, passing through the bottom 101 and the corner portions 104a, 104b, respectively, and are formed so that their depths become shallower at the upper end portions of the left side wall 102 and the right side wall 103. Two fitting portions 121a, 121b are formed on each of the connecting portions 120a, 120b. Flat-extending mounting portions 122a, 122b are formed at the upper end portions of the left side wall 102 and the right side wall 103 at the connecting portions 120a, 120b. The mounting portions 122a, 122b are used to detachably mount elongated, plate-shaped angle bars (not shown).

[0030] (Manufacturing method of U-shaped gutter 100) Next, a method for manufacturing the U-shaped gutter 100 configured in this manner will be described with reference to Figures 4 to 7. First, in the first step, an operator manufacturing the U-shaped gutter 100 prepares a molding die 300 for molding the pre-U-shaped gutter 200. Here, as shown in Figure 5, the pre-U-shaped gutter 200 is a semi-finished product before the U-shaped gutter 100 is completed, and is molded by the molding die 300.

[0031] Specifically, the pre-U-shaped gutter 200 has the bottom 101, left side wall 102, right side wall 103, corner portions 104a, 104b, bellows portion 110 and connecting portions 120a, 120b of the U-shaped gutter 100, and in addition to these, a bottom opposing surface 201 is molded.

[0032] The bottom-facing surface 201 is a portion that is formed between the left side wall 102 and the right side wall 103 while being directly connected to the left side wall 102 and the right side wall 103, respectively, and connects the left side wall 102 and the right side wall 103, and is formed in a plane that faces the bottom 101. The bottom-facing surface 201 includes a bellows-shaped facing surface 202 and connecting portion facing surfaces 203a and 203b, respectively.

[0033] The bellows-shaped opposing surface 202 is a portion formed opposite the bellows portion 110 formed on the bottom portion 101, and is formed in a bellows shape similar to the bellows portion 110 formed on the bottom portion 101. Inclined portions 102a and 103a, which extend in a curved shape while maintaining the bellows shape, are formed at both widthwise ends of the bellows-shaped opposing surface 202. In this case, the inclined portions 102a and 103a are formed in the same shape as the corner portions 104a and 104b, which are vertically symmetrical. In other words, the pre-U-shaped gutter 200 is formed such that the bellows portion 110 is uniformly and continuously connected to the bottom portion 101, the corner portions 104a and 104b, the left side wall 102, the right side wall 103, the inclined portions 102a and 103a, and the bottom opposing surface 201.

[0034] The connecting portion facing surfaces 203a, 203b are portions formed opposite the connecting portions 120a, 120b formed on the bottom portion 101, respectively, and are formed to extend in a planar shape. More specifically, the connecting portion facing surfaces 203a, 203b extend inward in a curved shape from the respective tips of the mounting portions 122a, 122b, and then are formed in a planar shape extending parallel to the bottom portion 101. As a result, the pre-U-shaped gutter 200 has a substantially rectangular cross section.

[0035] Therefore, the molding die 300 is formed in a shape for molding the pre-U-shaped groove 200, specifically, in a concave shape obtained by inverting the pre-U-shaped groove 200. In this case, the molding die 300 is It is composed of a left mold 301 for molding the left half of the pre-U-shaped gutter 200 and a right mold 302 for molding the right half of the pre-U-shaped gutter 200. Then, an operator attaches the prepared molding mold 300 to a blow molding machine (not shown). Here, the blow molding machine is a known mechanical device that introduces molten resin material into a mold and cools it to obtain a resin molded product.

[0036] Next, in the second step, the worker molds the pre-U-shaped gutter 200. Specifically, the worker operates the blow molding machine to introduce a parison P, which is formed into a cylindrical shape by melting a resin material, between a left mold 301 and a right mold 302 that constitute a pair of molding dies 300, as shown in Fig. 6(A), and then closes the left mold 301 and the right mold 302 to blow gas into the parison P from inside. As a result, the parison P adheres closely to the inner surfaces of the left mold 301 and the right mold 302, as shown in Fig. 6(B).

[0037] In this case, the blow molding machine appropriately controls the introduction timing, introduction temperature, introduction amount, introduction speed, air blow timing, air blow supply amount, air blow temperature, temperature of the molding die 300, and cooling timing of the molding die 300 to mold the pre-U-shaped groove 200. After cooling the molding die 300, the blow molding machine opens the left mold 301 and the right mold 302. This allows the worker to obtain the pre-U-shaped groove 200.

[0038] In this case, as shown in Fig. 7, the pre-U-shaped gutter 200 is molded in such a state that the end of the connecting portion 120a, which is one of both ends of the pre-U-shaped gutter 200 and which faces the bottom of the molding die 300, is closed by the bag portion 204a, and the introduction side of the parison P (the upper side in the figure) is closed by the bag portion 204b, leaving a space for air blowing. This second step of molding the pre-U-shaped gutter 200 corresponds to the pre-U-shaped gutter molding step according to the present invention. Note that the bag portions 204a and 204b are formed in accordance with the blow molding method of this embodiment and are not necessarily required for the pre-U-shaped gutter 200.

[0039] Next, in the third step, the worker removes the bottom facing surface 201 of the pre-U-shaped gutter 200. Specifically, the worker uses a cutting tool such as a jigsaw to cut off each of the bag portions 204a and 204b of the pre-U-shaped gutter 200 (see FIG. 5). Next, the worker uses the cutting tool to cut off each of the connecting portion facing surfaces 203a and 203b of the pre-U-shaped gutter 200. Next, the worker uses the cutting tool to cut off the bellows-shaped facing surface 202 of the pre-U-shaped gutter 200.

[0040] In this case, the worker cuts off the inclined portions 102a, 103a or the bellows-shaped opposing surface 202 so that at least a portion of the inclined portions 102a, 103a remains at the upper end portions of the left side wall 102 and the right side wall 103. This allows the worker to complete the U-shaped gutter 100 (see FIG. 1). The step of removing the bottom opposing surface 201 in this third step corresponds to the bottom opposing surface removing step according to the present invention.

[0041] (U-shaped gutter 100 operation) The U-shaped gutter 100 thus constructed is constructed such that multiple U-shaped gutter 100 are connected to each other in a long shape via the connecting portions 120a, 120b at the construction site, and the outer surface is buried in the ground or concrete. This allows the U-shaped gutter 100 to form a three-sided waterway with an open channel structure that opens upward. In this case, the U-shaped gutter 100 is installed with the bellows portion 110 bent appropriately according to the shape of the waterway. In other words, workers can install the U-shaped gutter 100 by bending the bellows portion 110 in each of the up, down, left, and right directions.

[0042] In this case, the worker must determine the thickness t of the mountain portion 111 of the bellows portion 110. 111 The thickness t of the valley portion 112 112 In other words, bellows portion 110 can be easily deformed by reducing the thickness of peak portions 111 located outside valley portions 112, thereby making it easier to bend as a whole.

[0043] The U-shaped gutter 100 functions as a waterway as water flows through the U-shaped gutter 100. In this case, the U-shaped gutter 100 has a wall thickness t 112 The thickness of the peak 111 is t 111 Since the groove is formed thicker than the groove, damage such as wear or tear caused by contact with water flowing through the groove or foreign matter can be suppressed.

[0044] As can be seen from the above operational description, according to the above embodiment, the manufacturing method for the U-shaped gutter 100 forms the cross-sectional shape of the U-shaped gutter 100 into a substantially rectangular cylindrical body with a bottom-facing surface 201 directly connected to the two side walls, the left side wall 102 and the right side wall 103, and facing the bottom 101. This allows the U-shaped gutter 100 to be formed into a small depth. In this case, workers may immediately perform the bottom-facing surface removal process on the pre-U-shaped gutter 200, which is formed from a cylindrical body in the pre-U-shaped gutter forming process. However, because the pre-U-shaped gutter 200 is formed as a cylindrical body, it can be stored or transported in a space-saving manner while suppressing changes in shape over time. The bottom-facing surface removal process can be performed at the factory or construction site when the U-shaped gutter 100 is needed. As a result, the manufacturing method for the U-shaped gutter 100 according to the present invention allows for the formation of a U-shaped gutter with high precision in a space-saving manner.

[0045] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the object of the present invention.

[0046] For example, in the above embodiment, the bellows-shaped opposing surface 202 is formed on the bottom opposing surface 201 in the pre-U-shaped groove forming process. However, in the pre-U-shaped groove forming process, it is sufficient to form the bottom opposing surface 201 on the pre-U-shaped groove 200. Therefore, in the pre-U-shaped groove forming process, for example, the bottom opposing surface 201 can also be formed as a flat plane.

[0047] In the above embodiment, the pre-U-shaped groove molding process is configured to mold the pre-U-shaped groove 200 by blow molding. However, the pre-U-shaped groove molding process can also mold the pre-U-shaped groove 200 using various molding methods other than blow molding, such as rotational molding, injection molding, vacuum molding, pressure molding, and extrusion molding.

[0048] In the above embodiment, the worker manually removed the bottom opposing surface 201 using a cutting tool in the bottom opposing surface removing step. However, it goes without saying that the worker may automatically use a machine to remove the bottom opposing surface 201, including removing the pre-U-shaped groove 200 from the molding die 300.

[0049] In the above embodiment, the worker immediately performed the bottom-facing surface removal process after the pre-U-shaped groove forming process in the second process. However, the bottom-facing surface removal process in the third process can be performed after the pre-U-shaped groove forming process in the second process, when the U-shaped groove 100 is shipped or when the U-shaped groove 100 is used. In other words, the bottom-facing surface removal process in the third process can be performed after the pre-U-shaped groove forming process in the second process, when the U-shaped groove 100 is temporarily stored, or on-site after the U-shaped groove 100 is transported to the specified site.

[0050] In the above embodiment, the U-shaped gutter 100 is configured with the connecting portions 120a and 120b. However, the U-shaped gutter 100 may be configured without the connecting portions 120a and 120b. In this case, the pre-U-shaped gutter 200 can also omit the connecting portion facing surfaces 203a and 203b.

[0051] Furthermore, in the above embodiment, the U-shaped gutter 100 is formed so that the bellows portion 110 can bend in all directions, up and down, left and right. That is, the U-shaped gutter 100 is configured as a joint that movably connects two U-shaped gutter 100. However, the U-shaped gutter 100 may be configured so that the bellows portion 110 has rigidity that makes it unable to bend. The U-shaped gutter 100 can also be configured as a joint that fixedly connects two U-shaped gutter 100, or as a U-shaped gutter that forms a waterway that extends unbendably.

[0052] Furthermore, in the above embodiment, the U-shaped gutter 100 is configured to include the bellows portion 110 and the connecting portions 120a and 120b. However, the U-shaped gutter 100 may be configured to include the bellows portion 110 on the bottom 101, left side wall 102, and right side wall 103. Therefore, the U-shaped gutter 100 may be configured to include a flat water channel portion that is not bellows-shaped, in addition to the bellows portion 110 on the bottom 101, left side wall 102, and right side wall 103.

[0053] In the above embodiment, the U-shaped gutter 100 is configured with the inclined portions 102a and 103a. This allows the U-shaped gutter 100 to improve the rigidity of the left side wall 102 and the right side wall 103. However, the U-shaped gutter 100 can also be configured without the inclined portions 102a and 103a. In this case, it is not necessary to form the inclined portions 102a and 103a in the pre-U-shaped gutter 200 in the pre-U-shaped gutter molding process.

[0054] In the above embodiment, the inclined portions 102a and 103a are formed as curved surfaces. However, the inclined portions 102a and 103a may be formed as shapes other than curved surfaces, for example, as inclined surfaces. In this case, in the pre-U-shaped groove forming step, the inclined portions 102a and 103a formed as inclined surfaces are formed on the pre-U-shaped groove 200.

[0055] In the above embodiment, the bellows portion 110 has a thickness of the peak portion 111 (wall thickness t 111 ) to the thickness of the valley portion 112 (wall thickness t 112) is formed thinner than the peaks 111. This allows the U-shaped groove 100 to easily bend the bellows portion 110. However, the bellows portion 110 may be formed so that the thickness of the peaks 111 is thicker than the thickness of the valleys 112, or the thickness of the peaks 111 and the valleys 112 may be formed to be the same thickness. [Explanation of symbols]

[0056] P...Parison, t 111 …height of the peak, t 112 ...valley thickness, 100...U-shaped groove, 101...Bottom part, 102...Left side wall, 102a...Tilt part, 103...Right side wall, 103a...Tilt part, 104a, 104b...Corner part, 110... bellows portion, 111... peak portion, 112... valley portion, 120a, 120b...connecting portion, 121a, 121b...fitting portion, 122a, 122b...mounting portion, 200... Pre-U-shaped groove, 201... Bottom opposing surface, 202... Bellows-shaped opposing surface, 203a, 203b... Connecting portion opposing surface, 204a, 204b... Bag portion, 300...molding die, 301...left die, 302...right die.

Claims

1. A method for manufacturing a resin U-shaped channel having a bottom through which water flows and two side walls standing up from both ends of the bottom in the width direction, with the top of the bottom open, and a bellows-like bellows portion formed by alternating mountain folds and valley folds on at least a part of the bottom and the two side walls, a pre-U-shaped groove molding process in which a pre-U-shaped groove is molded in a mold, the pre-U-shaped groove having a cross-sectional shape of a substantially square cylinder, the pre-U-shaped groove including, in addition to the bottom and the two side walls, bottom-facing surfaces that are directly connected to the two side walls and face the bottom but do not constitute the U-shaped groove; A method for manufacturing a U-shaped groove, comprising: a bottom opposing surface removal step of removing the bottom opposing surface of the pre-U-shaped groove removed from the mold.

2. In the method for manufacturing a U-shaped gutter described in claim 1, The pre-U-shaped groove forming step includes: A method for manufacturing a U-shaped gutter, characterized in that both ends of the pre-U-shaped gutter are molded in a state where they are closed with bag portions.

3. The method for manufacturing a U-shaped gutter according to claim 1 or 2, The bellows portion is A method for manufacturing a U-shaped gutter, characterized in that the U-shaped gutter is formed so as to be bendable in both the left-right direction and the up-down direction.

4. 4. The method for manufacturing a U-shaped groove according to claim 1, The pre-U-shaped groove forming step includes: A method for manufacturing a U-shaped gutter, characterized in that a bellows-shaped opposing surface is formed on the bottom opposing surface, which is continuously connected to the bellows portions formed on each of the two side walls.

5. 5. The method for manufacturing a U-shaped groove according to claim 1, The pre-U-shaped groove forming step includes: a tilted portion extending in an inclined or curved shape is formed at a corner between the two side walls and the bottom opposing surface, The bottom facing surface removing step includes: A method for manufacturing a U-shaped groove, characterized in that the bottom opposing surface is removed while leaving at least a portion of the inclined portion.

6. 6. The method for manufacturing a U-shaped groove according to claim 1, The bellows portion is A method for manufacturing a U-shaped gutter, characterized in that the thickness of the valley fold portion is formed thicker than that of the mountain fold portion.

7. 7. The method for manufacturing a U-shaped groove according to claim 1, The U-shaped groove is The bottom and the two side walls of at least one of both ends of the U-shaped gutter each extend in the direction of water flow to form a connecting portion for connecting with another U-shaped gutter, The pre-U-shaped groove forming step includes: a connecting portion facing surface is formed on the bottom facing surface, the connecting portion being continuously connected to the connecting portion formed on each of the two side walls; The bottom facing surface removing step includes: A method for manufacturing a U-shaped gutter, characterized by removing the opposing surface of the connecting portion.

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