JP2014124788A - Opening structure of blow molded body and method for forming the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an opening structure of a blow molded body, with which flatness of the opening is retained, by thinning the wall of the opening of a fuel tank etc. and improving stiffness of the opening, and to provide a method for forming the same.SOLUTION: An opening 10 of a blow molded body has an opening outer wall section 15, an opening upper wall section 13, and an opening inner wall section 11, and the opening inner wall section 11 has been formed continuously and circumferentially along the opening with a width nearly equal to the width of the opening. A blow molding mold 20 is equipped with an opening outer wall forming section 25 for forming the opening outer wall section 15 and the opening upper wall section 13. A slidable and cylindrical opening cutting blade 30 is installed on a side more inner than the opening outer wall forming section 25. The opening cutting blade 30 has a cutting blade root section 31 and a cutting blade tip section 32, and an outer diameter of the cutting blade root section 31 is larger than that of the cutting blade tip section 32. A parison is cut off with the cutting blade tip section 32 while leaving a width for forming the opening inner wall section 11, and the opening inner wall section 11 is formed by bending a section for forming the opening inner wall section 11 to the inside with the cutting blade root section 31.

Description

  The present invention relates to an opening structure of a blow molded article formed of a thermoplastic synthetic resin and a method for forming the opening structure.

Conventionally, the structure of a hollow body such as a fuel tank for automobiles has been made of metal. However, in recent years, the weight of the vehicle is reduced, rust is not generated, and it is easy to mold into a desired shape. For example, those made of thermoplastic synthetic resin have been used.
For the production of a hollow body made of a thermoplastic synthetic resin, a blow molding method has been often used because of the ease of molding the hollow body. In the blow molding method, a melted thermoplastic synthetic resin member parison is formed into a cylindrical shape, extruded from a die of a blow molding machine, the parison is sandwiched between molds, and air is blown into the parison to form a hollow body such as an automobile fuel tank. Was producing blow molded products.

As shown in FIG. 1, the blow-molded product has an opening for taking in and out a component to be mounted inside the hollow body. The opening is formed by integrally forming the opening 110 at the same time that the blow molded article 101 is formed by blow molding.
For example, as shown in FIGS. 14 to 16, the opening 110 is formed by providing a slidable rotary blade 130 on the blow molding die 120 and cutting the outer wall 102 of the blow molded product 101 ( For example, see Patent Document 1.)

  As shown in FIGS. 14 to 16, the opening 110 is formed by forming a cutting edge 133 at the tip of the rotary blade 130, positioning the cutting edge 133 slightly protruding into the cavity 126, and setting the cutting edge 131 in advance. Blow molding is performed in a state of entering the inside of the mold surface of the blow molding die 120, and the resin parison is brought into close contact with the cutting edge 131 to form the blow molded product 101. Thereafter, as shown in FIG. 15, the rotary blade 130 is rotated to cut away the cut portion 118 of the opening 110 to form the opening 110.

  However, in this method, it is possible to form the flange portion 111 by slightly projecting the blade edge 133 into the cavity 126 at the opening portion 110, but when the blade edge 133 is largely protruded, the parison is broken or wrinkled. For this reason, it is difficult to increase the width of the flange portion 111. Moreover, since the parison 5 is extended by the blade edge 133, the flange portion 111 cannot obtain sufficient rigidity.

  Further, since the lid is attached to the opening 110, there is a limit to reducing the thickness of the screw portion when forming the screw portion. In addition, since the upper surface 113 of the opening 110 contracts after the opening 110 is cut, it is difficult to ensure the flatness of the upper surface 113 of the opening. Therefore, it is necessary to devise a sealing property between the opening 110 and the lid.

JP 2010-76297 A

  Therefore, the present invention can easily form an opening even in a blow molded product with a thick outer wall such as a fuel tank, improve the thickness of the opening and improve the rigidity of the opening, and ensure the flatness of the opening. It is an object of the present invention to provide a blow molded article opening structure and a method for forming the same.

The present invention of claim 1 for solving the above-described problem is an opening structure of a synthetic resin blow-molded product that forms an opening of a molded product formed by blow molding.
The opening extends from the outer wall of the molded product and is integrally bent from the outer wall to the outside of the molded product, and is integrally formed from the front end of the opening outer wall to the center of the opening. An opening upper wall portion extending to the opening, and an opening inner wall portion formed by bending integrally from the tip of the opening upper wall portion to the inside of the molded product,
The inner wall portion of the opening is a blow molded product opening structure characterized by being continuously formed in a circumferential shape with substantially the same width along the opening.

  According to the first aspect of the present invention, the opening extends from the outer wall of the molded product and is formed by bending the outer wall integrally from the outer wall to the outside of the molded product, and from the tip of the opening outer wall. Formed from an opening upper wall that is integrally extended in the center direction of the opening, and an opening inner wall that is formed by bending from the tip of the opening upper wall to the inside of the molded product. Is done. Therefore, the outer wall of the opening, the upper wall of the opening, and the inner wall of the opening can be formed simultaneously with the blow molding, and a screw or the like is provided on the outer surface of the outer wall of the opening to close the opening. Can be installed. An inner surface such as a lid can be brought into contact with the upper wall portion of the opening to ensure the sealing performance of the opening. The opening inner wall can secure the rigidity of the opening.

  Since the inner wall portion of the opening is continuously formed in a circumferential shape with substantially the same width along the opening portion, the rigidity of the inner wall portion of the opening portion is increased over the entire circumference of the opening portion, and the wall of the outer wall portion of the opening portion is increased. The rigidity of the opening can be ensured without increasing the thickness, and deformation of the upper wall of the opening can be prevented, and the flatness of the upper wall of the opening can be ensured.

  The present invention of claim 2 is an opening structure of a blow-molded product in which the outer wall of the opening, the upper wall of the opening, and the inner wall of the opening are formed with substantially the same thickness.

  In the second aspect of the present invention, the opening outer wall portion, the opening upper wall portion, and the opening inner wall portion are formed with substantially the same thickness. In order to increase the overall rigidity of the opening, increase the thickness of the parison to increase the rigidity of the opening, it is not necessary to increase the thickness of the outer wall of the opening, reducing the weight of the blow molded product Can contribute.

  The present invention of claim 3 is the blow-molded product opening structure in which the opening outer wall portion and the opening inner wall portion are formed substantially at right angles to the outer wall of the molded product.

  In the third aspect of the present invention, the opening outer wall portion and the opening inner wall portion are formed substantially at right angles to the outer wall of the molded product. Therefore, the opening outer wall portion covers the opening and the like. The opening inner wall portion is formed integrally with the opening upper wall portion and the opening outer wall portion, so that the rigidity of the opening outer wall portion can be improved.

  The present invention of claim 4 is the blow-molded product opening structure in which the width of the inner wall of the opening is at least half the width of the outer wall of the opening.

  In the present invention of claim 4, since the width of the inner wall portion of the opening is formed to be at least half the width of the outer wall portion of the opening, the rigidity of the inner wall portion of the opening can be sufficiently improved. The rigidity of the outer wall portion of the opening can be improved without increasing the thickness of the outer wall portion.

  The present invention of claim 5 is an opening structure of a blow-molded product in which the upper wall portion of the opening has a flat outer surface.

  In the present invention of claim 5, since the outer surface of the opening upper wall portion is formed in a flat shape, the lid attached to the opening portion and the outer surface of the opening upper wall portion can be in close contact with each other, and sealing performance is ensured. can do.

The present invention of claim 6 is a method for forming an opening of a synthetic resin blow-molded product in which an opening of a molded product formed by blow molding is formed in a blow mold.
The opening extends from the outer wall of the molded product and is integrally bent from the outer wall to the outside of the molded product, and is integrally formed from the front end of the opening outer wall to the center of the opening. An opening upper wall portion extending to the opening, and an opening inner wall portion formed by bending integrally from the tip of the opening upper wall portion to the inside of the molded product,
The blow molding die is provided with an opening outer wall forming portion that forms an opening outer wall portion and an opening upper wall portion in a portion corresponding to the opening portion of the blow molded product, and the opening portion is formed more than the opening outer wall forming portion. A cylindrical opening cutting blade that can slide inside and outside the cavity is provided inside, and the opening cutting blade has a cutting blade root and a cutting blade tip. The outer diameter of the cutting blade root is It is formed larger than the outer diameter of the blade tip, and the outer surface of the cutting blade base and the outer surface of the cutting blade tip are continuously formed so that the outer diameter gradually changes on the cutting blade inclined surface,
At the time of blow molding, after closely attaching the parison to the opening outer wall molding part,
Inside the parison opening, slide the opening cutting blade and leave the width to form the opening inner wall from the part that forms the upper wall of the opening that is in close contact with the outer wall forming part of the opening of the parison at the tip of the cutting blade The opening of the blow-molded product is characterized in that the portion of the inner wall of the opening that is left uncut by the parison is bent inwardly at the base of the cutting blade to form the inner wall of the molded product. It is a part formation method.

  In the present invention of claim 6, the opening extends from the outer wall of the molded product and is integrally bent from the outer wall to the outside of the molded product, and from the tip of the outer wall of the opening. Formed from an opening upper wall that is integrally extended in the center direction of the opening, and an opening inner wall that is formed by bending from the tip of the opening upper wall to the inside of the molded product. Is done. Therefore, the outer wall of the opening, the upper wall of the opening, and the inner wall of the opening can be formed simultaneously with the blow molding, and a screw or the like is provided on the outer wall of the opening to attach a lid or the like that closes the opening. be able to. The sealing of the opening can be ensured by bringing a lid or the like into contact with the upper wall of the opening. The opening inner wall can secure the rigidity of the opening.

  The blow molding die is provided with an opening outer wall forming portion that forms an opening outer wall portion and an opening upper wall portion at a portion corresponding to the opening of the blow molded product. For this reason, the opening outer wall part and the opening upper wall part of an opening part can be formed by inflating a parison at the time of blow molding, and making it closely_contact | adhere to an opening part outer wall shaping | molding part.

  A cylindrical opening excision blade slidable in and out of the cavity was provided inside the opening rather than the outer wall forming part of the opening. For this reason, the part corresponding to the opening part of a parison can be cut off by sliding an opening part cutting blade with respect to the parison closely_contact | adhered to the blow molding metal mold | die at the time of blow molding.

  The opening cutting blade has a cutting blade root and a cutting blade tip, and the outer diameter of the cutting blade root is formed larger than the outer diameter of the cutting blade tip and cuts the outer surface of the cutting blade root and the cutting blade. The outer surface of the blade tip was formed continuously so that the outer diameter gradually changed on the cutting blade inclined surface. For this reason, the parison can be cut off at the cutting blade tip, and the periphery of the cutting portion of the parison can be bent in the inner direction of the molded product by sliding the opening cutting blade at the cutting blade inclined surface and the cutting blade root.

  The part which forms the opening upper wall part closely attached to the opening outer wall molding part of the parison at the cutting blade tip after sliding the opening cutting blade after the parison is closely attached to the opening outer wall molding part at the time of blow molding The inner part of the opening of the parison is cut away, leaving a width for forming the inner wall of the opening. For this reason, the portion corresponding to the opening of the parison can be cut at the tip of the cutting blade by sliding the opening cutting blade while holding the parison with the blow molding die.

  The opening cutting blade is slid, and the portion forming the opening inner wall portion left uncut by the parison is bent inward of the molded product at the cutting blade root portion to form the opening inner wall portion. For this reason, simultaneously with the blow molding, the outer wall portion of the opening and the upper wall portion of the opening portion are formed by the blow molding die in the opening portion of the molded product, and the inner wall portion of the opening portion is continuously formed from the upper wall portion of the opening portion. In addition, the outer wall portion of the opening and the inner wall portion of the opening can be formed substantially in parallel.

  According to the seventh aspect of the present invention, the opening inner wall portion is formed by slightly bending a portion of the cutting blade tip portion forming the opening inner wall portion left uncut by the parison with the cutting blade inclined surface, and then at the cutting blade root portion. This is a method for forming an opening of a blow-molded product that is formed by being bent in parallel with the outer wall of the opening.

  In the present invention of claim 7, the formation of the inner wall portion of the opening portion is performed by slightly bending a portion of the cutting blade tip portion forming the opening inner wall portion left uncut by the parison with the cutting blade inclined surface, and then at the cutting blade root portion. It is formed by bending parallel to the outer wall of the opening. Therefore, the inner wall portion of the opening portion can be smoothly bent continuously with the upper wall portion of the opening portion to form the outer wall portion of the opening portion and the inner wall portion of the opening portion substantially in parallel.

  The present invention of claim 8 is the blow-molded product opening forming method in which the cutting edge of the cutting blade tip is formed into a plurality of chevron shapes.

  In the present invention of claim 8, since the cutting edge of the cutting blade tip portion is formed in a plurality of chevron shapes, when cutting the parison at the cutting blade tip portion, the cutting edge of the cutting blade tip portion formed in a plurality of chevron shapes is used. It is possible to cut in at a plurality of locations of the parison, so that the parison can be easily excised, the deformation of the parison is small, and the melted parison can be excised into a uniform circle.

  In the ninth aspect of the present invention, a receiving block is provided inside the cylindrical shape of the opening cutting blade, and the inner surface of the opening cutting blade slides on the outer periphery of the receiving block, and the opening is formed on the tip surface of the receiving block. This is a blow molded product opening forming method for closely attaching a parison cut by a cutting blade and removing the parison closely attached to the front end surface of the receiving block after blow molding.

  In the present invention of claim 9, a receiving block is provided inside the cylindrical shape of the opening cutting blade, and the inner surface of the opening cutting blade slides on the outer periphery of the receiving block, and the opening is formed on the tip surface of the receiving block. The parison cut off by the cutting blade comes into close contact, and after blow molding, the parison attached to the front end surface of the receiving block is removed. For this reason, the parison is placed in close contact with the block, making it easy to cut the parison with the opening cutting blade and securely holding the parison cut with the opening cutting blade so that the parison cut after blow molding is removed from the molded product. It can be removed reliably.

  The present invention of claim 10 is a blow molded product opening forming method in which a ventilation hole is formed inside the cutting blade root portion of the opening cutting blade.

  In the present invention of claim 10, because the vent hole is formed inside the cutting blade root portion of the opening cutting blade, after opening the cutting blade into the cavity of the blow mold and cutting the parison, Air can be blown from the vent holes to cool the tank opening, shortening the molding cycle and improving productivity.

  The present invention of claim 11 is a blow molded product opening forming method in which a groove portion for forming a screw portion is formed on the outer surface of the opening outer wall portion in the opening outer wall forming portion of the blow molding die.

  According to the present invention of claim 11, since the groove portion for forming the screw portion is formed on the outer surface of the opening outer wall portion in the opening outer wall forming portion of the blow molding die, the screw is formed on the outer surface of the opening outer wall portion simultaneously with the blow molding. A portion can be formed, and a lid or the like can be easily attached to the opening.

  In the present invention, the opening is formed from the opening outer wall, the opening inner wall formed integrally with the opening upper wall, and thus the opening outer wall, the opening upper wall, and The opening structure of the blow molded product and the forming method thereof can form the opening inner wall simultaneously with the blow molding, and the rigidity of the opening can be secured by the opening inner wall. Since the inner wall portion of the opening is continuously formed in a circumferential shape with substantially the same width along the opening portion, the rigidity of the inner wall portion of the opening portion is increased over the entire circumference of the opening portion, and the wall of the outer wall portion of the opening portion is increased. Rigidity can be secured without increasing the thickness, and deformation of the upper wall portion of the opening can be prevented, and the flatness of the upper wall portion of the opening can be secured.

It is a perspective view of the fuel tank which has the opening part of the blow molded product which is embodiment of this invention. It is sectional drawing of the opening part of the blow molded product which is embodiment of this invention. It is sectional drawing of the opening part of the blow molded product which is other embodiment of this invention. It is sectional drawing of the opening part of the blow molded product which is other embodiment of this invention. It is sectional drawing of the part which forms the opening part of the blow molding metal mold | die used for embodiment of this invention, an opening part cutting blade retreats from the front end surface of a receiving block, and a parison is contact | adhered to a cavity. It is sectional drawing. It is sectional drawing of the part which forms the opening part of the blow molding die used for embodiment of this invention, and the cutting blade front-end | tip part of an opening part cutting blade enters the inside of a cavity from the front end surface of a block, and it is a parison. It is sectional drawing of the state which excised the part corresponding to this opening part. It is sectional drawing of the part which forms the opening part of the blow molding die used for embodiment of this invention, and an opening part cutting blade enters the inside of a cavity from the front end surface of a block, and respond | corresponds to the opening part of a parison It is sectional drawing of the state which cut | disconnected the part to perform and also the cutting blade base part of the opening part cutting blade approached the cavity. It is sectional drawing of the part which forms the opening part of the blow molding die used for embodiment of this invention, and after the opening part cutting blade cuts off the part corresponding to the opening part of a parison, to the part of the front end surface of a block It is sectional drawing of the state which retracted. It is sectional drawing of the part which forms the opening part of the blow molding die used for embodiment of this invention, and is sectional drawing of the state which removes the parison cut from the receiving block after blow molding. It is sectional drawing of the cutting blade front-end | tip part of the opening part cutting blade used for embodiment of this invention. It is sectional drawing of the cutting blade front-end | tip part of the other opening part cutting blade used for embodiment of this invention. It is sectional drawing of the cutting blade front-end | tip part of the other opening part cutting blade used for embodiment of this invention. It is sectional drawing of the cutting blade front-end | tip part of the other opening part cutting blade used for embodiment of this invention. It is sectional drawing of the state before excising the opening part of the opening shaping | molding part of the conventional blow molding die. It is sectional drawing of the state which cuts off the opening part of the opening shaping | molding part of the conventional blow molding die. It is sectional drawing of the state after excising the opening part of the opening shaping | molding part of the conventional blow molding die.

  An opening structure of a blow molded article and a method for forming the same according to an embodiment of the present invention will be described with reference to FIGS. To do. First, an opening structure of an automobile fuel tank will be described with reference to FIGS. 1 to 4, and thereafter, a method of forming an opening of an automobile fuel tank will be described.

FIG. 1 is a perspective view of a fuel tank 1 having a tank opening 10 formed in the embodiment of the present invention. 2-4 is sectional drawing which shows two aspects in the tank opening part 10 of embodiment of this invention.
In the embodiment of the present invention, as shown in FIG. 1, the fuel tank 1 has a tank opening 10 for taking in and out components attached to the inside of the fuel tank 1 such as a fuel pump (not shown). Is formed.

The fuel tank 1 is formed by blow molding, and its outer wall is composed of only one layer, or five layers including an outer layer, an inner layer, an intermediate layer formed between the outer layer and the inner layer, and an adhesive layer thereof. In blow molding, a parison composed of one or five layers as described above is used.
In the case of five layers, the outer layer and the inner layer are formed from a thermoplastic synthetic resin that has high strength and maintains strength against fuel oil, and the intermediate layer is formed from a thermoplastic synthetic resin that has very little permeation of fuel oil. The adhesive layer is made of a thermoplastic synthetic resin that bonds the outer layer and the intermediate layer and the inner layer and the intermediate layer, respectively.

  As shown in FIG. 1, the tank opening 10 is formed on the upper surface of the fuel tank 1, and the tank opening 10 is left as the tank opening 10 so that a fuel pump or the like is assembled. In some cases, the body is attached and locked, or in the tank opening 10, the fuel supply pipe 4, the vent valve 3, and the like are welded.

As shown in FIG. 2, the tank opening 10 is integrally formed from an opening outer wall 15, an opening upper wall 13, and an opening inner wall 11.
The opening outer wall portion 15 is integrally extended from the tank main body outer wall 2 and is integrally bent outward. The opening outer wall portion 15 is preferably formed to be bent at a substantially right angle with respect to the tank body outer wall 2. An opening outer wall screw portion 16 is formed on the outer surface of the opening outer wall portion 15. For this reason, a lid (not shown) or the like for closing the tank opening 10 can be screwed.

  An opening upper wall portion 13 is integrally extended from the front end of the opening outer wall portion 15 in the center direction of the tank opening portion 10, that is, in parallel with the tank body outer wall 2. The opening upper wall portion 13 is formed with an opening upper wall surface 14 whose outer surface is formed in a flat shape. For this reason, the inner surface of the lid or the like attached to the tank opening 10 and the upper wall surface 14 of the opening can be in close contact with each other, and sealing performance can be ensured. A seal ring may be attached to the upper wall surface 14 of the opening.

  An opening inner wall 11 is formed by bending integrally from the tip of the opening upper wall 13 in the center direction of the tank opening 10 to the inside of the fuel tank 1. For this reason, the opening inner wall part 11 and the opening outer wall part 15 are formed substantially in parallel. The opening inner wall 11 is continuously formed in a circumferential shape with substantially the same width along the tank opening 10. That is, as shown in FIG. 2, the opening inner wall 11 is formed in a ring shape having a certain width in the tank opening 10.

  Therefore, it is not necessary to increase the rigidity of the tank opening 10 that combines the opening outer wall 15 and the opening inner wall 11 over the entire circumference of the tank opening 10 and increase the thickness of the opening outer wall 15. Rigidity can be ensured. For this reason, it is not necessary to increase the wall thickness of the parison 5, and it is possible to contribute to weight reduction without increasing the wall thickness of the tank body outer wall 2 of the fuel tank 1. Moreover, deformation of the opening upper wall portion 13 after molding or in use can be prevented, the flatness of the opening upper wall portion 13 can be ensured, and the sealing performance of the tank opening portion 10 can be ensured. .

The opening inner wall surface 12, which is the surface on the center side of the tank opening 10, is formed as a smooth surface to ensure the rigidity of the opening inner wall 11 and attach components from the tank opening 10 to the inside of the fuel tank 1. Is easy.
An opening gap 17 is formed between the opening inner wall portion 11 and the opening outer wall portion 15. For this reason, the elasticity of the whole tank opening part 10 can also be ensured.

3 and 4 are other embodiments of the tank opening 10. Only the width of the opening inner wall portion 11 is different, and the shapes of the other outer wall portions 15 of the opening and the upper wall portion 13 of the opening are the same.
In the embodiment shown in FIG. 3, the width of the opening inner wall portion 11 is slightly narrower than that in the embodiment shown in FIG. 2. The width of the inner wall portion 11 of the opening is formed to be at least half the width of the outer wall portion 15 of the opening. For this reason, the rigidity of the opening inner wall part 11 can be sufficiently improved, and the rigidity of the opening outer wall part 15 can be improved without increasing the thickness of the opening outer wall part 15.

  In the embodiment shown in FIG. 4, the width of the opening inner wall portion 11 is narrower than that in the embodiment shown in FIG. 3. Even in this case, since the opening inner wall 11 has a predetermined width, the rigidity of the tank opening 10 including the opening outer wall 15 and the opening inner wall 11 is increased over the entire circumference of the tank opening 10. The rigidity can be ensured without increasing the thickness of the outer wall portion 15 of the opening.

Next, based on FIG. 5 to FIG. 13, as an example of the method for forming the opening of the blow molded product according to the embodiment of the present invention, the method for forming the tank opening 10 of the automobile fuel tank that is a blow molded product is shown. I will explain to you.
The blow molding die 20 usually sandwiches a synthetic resin parison 5 which is discharged in a molten state from a nozzle of a blow molding machine (not shown) located at the top of the blow molding die 20, with an internal cavity. It is formed by a blow molding die main body 21 divided into left and right two so as to be molded.

  As shown in FIG. 5, the portion of the blow molding die 20 used in the present invention that forms the tank opening 10 is connected to the blow molding die main body 21 on the side forming the upper portion of the fuel tank 1. An opening outer wall forming portion 25 that forms ten opening outer wall portions 15 and an opening upper wall portion 13 is provided. A cylindrical space that is the same as the inner diameter of the opening inner wall portion 11 is provided inside the tank opening 10 of the opening outer wall forming portion 25 of the blow molding die body 21, and a columnar receiving block 22 is provided at the center thereof. Is inserted.

  A ring-shaped slide space 24 is formed between the receiving block 22 and the blow mold body 21. An opening excision blade 30 is attached to the slide space 24 so as to be slidable on the outer periphery of the receiving block 22. A receiving block protrusion 23 is formed at the center of the front end surface of the receiving block 22.

  When the parison 5 is sandwiched and blown inside the blow mold 20, the parison 5 comes into close contact with the cavity surface 26 of the blow mold 20 as shown in FIG. Then, it closely_contact | adheres to the bottom face of the opening outer wall shaping | molding part 25 and the receiving block 22. FIG. Therefore, the opening outer wall 15 and the opening upper wall 13 of the tank opening 10 can be formed at the opening outer wall forming portion 25.

  In the portion of the opening outer wall forming portion 25 where the opening outer wall portion 15 is formed, the opening outer wall forming portion groove portion 25a for forming the opening outer wall screw portion 16 on the outer surface of the opening outer wall portion 15 can be formed. In this case, the opening outer wall screw portion 16 can be formed on the outer surface of the opening outer wall portion 15 simultaneously with the blow molding. In order to close the tank opening 10, a screw portion such as a lid (not shown) can be engaged with the opening outer wall screw portion 16 and can be easily attached.

Next, as shown in FIG. 6, the opening excision blade 30 is slid in the slide space 24 in the direction in the cavity (downward in FIG. 6).
The opening part cutting blade 30 has a cutting blade base part 31 and a cutting blade tip part 32, and the outer diameter of the cutting blade base part 31 is formed larger than the outer diameter of the cutting blade tip part 32. The outer surface of the cutting blade root portion 31 and the outer surface of the ridge portion of the cutting blade tip portion 32 are continuously formed by the cutting blade inclined surface 35 so that the outer shape thereof gradually changes. The thickness of the cutting blade base 31 is the same as the width of the slide space 24. For this reason, the opening part cutting blade 30 can slide the outer surface of the receiving block 22 smoothly.

  When the opening cutting blade 30 is slid after the parison 5 is brought into close contact with the opening outer wall forming portion 25, the portion of the cutting blade tip 32 that is in close contact with the receiving block 22 of the parison 5, that is, the opening outer wall forming portion 25. The portion that forms the opening inner wall portion 11 is left from the portion that is in close contact with the inner portion, and the inner portion that forms the tank opening 10 is cut out. Since the parison 5 is held by the receiving block 22 of the blow mold 20, the parison 5 is less deformed and corresponds to the tank opening 10 of the parison 5 at the cutting blade tip 32 by sliding the opening cutting blade 30. The part can be excised.

  Further, when the opening part cutting blade 30 is slid, the part of the parison 5 that forms the opening inner wall part 11 that is the part of the parison 5 that is left uncut by the width of the slide space 24 is cut off by the cutting blade inclined surface 35. This part can be bent toward the inside of the cavity. Since the cutting blade inclined surface 35 is inclined, the remaining portion of the parison 5 can be bent gradually, and can be bent smoothly.

  As shown in FIG. 7, when the opening cutting blade 30 is further slid, the portion that forms the opening inner wall portion 11 of the parison 5 that is left uncut is completely removed at the base portion 31 of the cutting blade. The opening inner wall portion 11 can be formed by bending. The opening inner wall portion 11 is formed at a right angle to the tank body outer wall 2 so as to be substantially parallel to the opening outer wall portion 15. For this reason, simultaneously with blow molding, the opening outer wall 15 and the opening upper wall 13 are formed by the blow molding die 20 and the opening inner wall 11 is formed continuously from the opening upper wall 13. Can do.

  By changing the thickness of the cutting blade base portion 31 and changing the width of the slide space 24 accordingly, as shown in FIGS. It is possible to change the width of the opening inner wall 11 by changing the width of the parison 5 forming the certain opening inner wall 11. In this way, the width of the opening inner wall portion 11 can be easily changed.

  Next, as shown in FIG. 8, the opening cutting blade 30 is retracted from the cavity (upward in FIG. 8), and the cutting edge 33 of the cutting blade tip 32 of the opening cutting blade 30 and the end face of the receiving block 22 are used. Also retreat. Thereby, the tank opening 10 can be formed. Then, the blown fuel tank 1 is removed from the blow mold 20.

  Next, as shown in FIG. 9, the parison 5 that is in close contact with the front end surface of the receiving block 22 is removed. Since the receiving block protrusion 23 is formed on the front end surface of the receiving block 22, the parison 5 that is cut out and in close contact with the receiving block 22 has a protruding portion along the receiving block protrusion 23. The protruding part is removed by the excision part removing machine 27. A plurality of arms 27 a are attached to the excision part removing machine 27, and the arms 27 a can remove the parison 5 that is in close contact with the receiving block 22 while holding the protruding part of the parison 5.

  The cutting edge 33 of the cutting blade tip 32 of the opening cutting blade 30 may be formed in a planar shape as shown in FIG. Moreover, as shown in FIG. 11 and FIG. 12, you may form in the cutting edge 33 mountain shape of the cutting blade front-end | tip part 32. FIG. In the case shown in FIG. 11, the cutting edge 33 is formed in four chevron shapes, and in the case shown in FIG. 12, the cutting edge 33 is formed in eight chevron shapes, but a plurality of chevron shapes should be selected as appropriate. Can do. When the cutting edge 33 is formed in a plurality of chevron shapes, the cutting edge 33 of the cutting blade tip portion 32 formed in a plurality of chevron shapes bites at a plurality of locations of the parison 5 when the parison 5 is cut by the cutting blade tip portion 32. The molten parison 5 can be cut into a uniform circle.

  As shown in FIG. 13, the vent hole 34 can be formed in the portion of the cutting blade base portion 31 of the opening cutting blade 30. In this case, the opening cutting blade 30 enters the cavity of the blow molding die 20 to cut the parison 5 and then blows air from the vent hole 34 to cool the parison 5 in the tank opening 10 portion. This can shorten the molding cycle and improve productivity.

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Tank main body outer wall 10 Tank opening part 11 Opening part inner wall part 13 Opening part upper wall part 15 Opening part outer wall part 20 Blow molding die 22 Receiving block 25 Opening part outer wall shaping part 30 Opening part cutting blade 31 Cutting blade base Part 32 Cutting blade tip 34 Vent hole 35 Cutting blade inclined surface

Claims (11)

In the opening structure of the blow molded product of synthetic resin that forms the opening of the molded product formed by blow molding,
The opening extends from the outer wall of the molded product and is formed by integrally bending the outer wall outward from the molded product, and the opening from the tip of the outer wall of the opening. An opening upper wall portion integrally extending in the center direction of the opening portion, and an opening inner wall portion formed by bending integrally from the tip of the opening upper wall portion to the inside of the molded product And
An opening structure of a blow molded product, wherein the inner wall of the opening is continuously formed in a circumferential shape with substantially the same width along the opening.   The opening structure of the blow molded product according to claim 1, wherein the outer wall portion of the opening portion, the upper wall portion of the opening portion, and the inner wall portion of the opening portion are formed with substantially the same thickness.   The blow-molded product opening structure according to claim 1 or 2, wherein the opening outer wall portion and the opening inner wall portion are formed substantially perpendicular to the outer wall of the molded product.   4. The blow-molded product opening structure according to claim 1, wherein a width of the inner wall portion of the opening is at least half as long as a width of the outer wall portion of the opening. 5.   The opening structure of the blow molded product according to any one of claims 1 to 4, wherein the upper wall portion of the opening portion has an outer surface formed in a flat shape. In the method of forming an opening of a synthetic resin blow-molded product in which an opening of a molded product formed by blow molding is formed in a blow molding die,
The opening extends from the outer wall of the molded product and is formed by integrally bending the outer wall outward from the molded product, and the opening from the tip of the outer wall of the opening. An opening upper wall portion integrally extending in the center direction of the opening portion, and an opening inner wall portion formed by bending integrally from the tip of the opening upper wall portion to the inside of the molded product And
The blow molding die is provided with an opening outer wall forming portion that forms the opening outer wall portion and the opening upper wall portion in a portion corresponding to the opening of the blow molded product, and from the opening outer wall forming portion. Also provided is a cylindrical opening cutting blade that can slide inside and outside the cavity inside the opening, and the opening cutting blade has a cutting blade root and a cutting blade tip, and the cutting blade root The outer diameter of the cutting portion is formed larger than the outer diameter of the cutting blade tip, and the outer surface of the cutting blade root and the outer surface of the cutting blade tip are continuously changed so that the outer diameter gradually changes with the cutting blade inclined surface. Let it form,
At the time of blow molding, after closely attaching the parison to the opening outer wall molding part,
Slide the opening cutting blade and leave the width to form the inner wall portion of the opening from the portion of the cutting blade tip portion that forms the opening upper wall portion that is in close contact with the opening outer wall molding portion of the parison. The inside part of the opening of the parison is excised, and the part forming the inner wall part of the opening left uncut by the parison is bent inward of the molded product at the base part of the cutting blade, and the inner wall part of the opening part is bent. Forming an opening of a blow molded product.   The opening inner wall is formed by slightly bending a portion of the cutting blade tip portion forming the opening inner wall portion left uncut by the parison with the cutting blade inclined surface, and then opening the opening at the cutting blade root portion. The blow-molded product opening forming method according to claim 6, wherein the blow-molded product is formed by being bent parallel to the outer wall portion.   The blow-molded product opening forming method according to claim 6 or 7, wherein the cutting edge of the cutting blade tip is formed in a plurality of chevron shapes.   A receiving block is provided inside the cylindrical shape of the opening cutting blade, and the inner surface of the opening cutting blade slides on the outer periphery of the receiving block. The blow-molded product opening forming method according to any one of claims 6 to 8, wherein the excised parison is in close contact, and the parison in close contact with the front end surface of the receiving block is removed after blow molding.   The blow-molded product opening forming method according to any one of claims 6 to 10, wherein a ventilation hole is formed inside the cutting blade base portion of the opening cutting blade.   The groove part which forms a screw part in the outer surface of the said opening outer wall part of the said blow molding metal mold | die was formed in the part which forms the said opening outer wall part of the said opening outer wall shaping | molding part. The method for forming an opening of a blow molded product according to any one of the above.

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