JP2015030116A - Method of forming opening part of blow molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a formation method of a blow molded article, capable of easily forming the opening part thereof within a blow molding mold.SOLUTION: There is provided a formation method of an opening part of a synthetic resin-made blow molded article to be formed within a blow molding mold. The opening part 10 is formed of an opening part outer wall, an opening part upper wall and an opening part inner wall 15, 13 and 11. The blow molding mold 20 comprises: an opening outer wall molding part 25 forming the opening part outer wall, the opening part upper wall and the opening part inner wall; and an opening part-cutting blade 27 slidable on the inside and the outside of a cavity or a parison 5 inside the opening part than the inner wall 11. In a blow molding process, the parison 5 is closely contacted with the molding part 25, and the blade 27 is made to slide. After that, the parison 5 inside the opening part 10 adjacent to the inner wall 11 is cut by a top 27b of the cutting blade.

Description

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

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. 23 to 25, 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. 23 to 25, the opening 110 is formed by forming a cutting edge 133 at the tip of the rotary blade 130, slightly protruding the blade 133 into the cavity 126 and positioning 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.

  Furthermore, since the lid is attached to the opening 110, when the screw portion is formed, the rigidity of the opening 110 is low, and there is a limit to reducing the thickness of 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, there has been a demand for a method in which the width of the flange portion 111 of the opening 110 is increased, the rigidity of the opening 110 is increased, and the cut portion 118 of the opening 110 can be easily cut.

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 problems is a synthetic resin blow-molded product opening forming method for forming an opening of a molded product formed by blow molding in a blow molding die.
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, an opening upper wall portion, and an opening inner wall portion in a portion corresponding to the opening portion of the blow molded product, and from the opening inner wall portion. Also provided an opening cutting blade slidable inside or outside of the cavity or in the parison inside the opening,
At the time of blow molding, after closely attaching the parison to the opening outer wall molding part,
An opening forming method for a blow-molded product, wherein the opening cutting blade is slid and the parison inside the opening close to the inner wall of the opening of the parison is cut off at the tip of the cutting blade.

  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. For this reason, while being able to form an opening outer wall part, an opening upper wall part, and an opening inner wall part simultaneously with blow molding, the rigidity of an opening part can be improved with an opening inner wall part. Moreover, a screw part etc. can be provided in an outer wall part of an opening part, and the lid | cover etc. which block | close an opening part can be attached. 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 blow molding die is provided with an opening outer wall forming portion that forms an opening outer wall portion, an opening upper wall portion, and an opening inner wall portion in a portion corresponding to the opening of the blow molded product. For this reason, it is possible to simultaneously form the opening outer wall portion, the opening upper wall portion, and the opening inner wall portion of the opening portion by inflating the parison at the time of blow molding and closely contacting the opening outer wall forming portion.

  An opening cutting blade slidable inside and outside the cavity or in a parison is provided inside the opening rather than the inner wall 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.

  At the time of blow molding, after the parison was brought into close contact with the outer wall forming portion of the opening, the opening cutting blade was slid, and the inner parison of the opening adjacent to the inner wall of the opening of the parison was excised at the tip of the cutting blade. For this reason, the portion corresponding to the opening of the parison can be cut off at the tip of the cutting blade by leaving the inner wall of the opening by sliding the opening cutting blade while holding the parison with the blow mold. Since it has the inner wall of the opening, the rigidity of the opening is large, and the strength of the opening is improved without increasing the thickness of the outer wall of the opening, the upper wall of the opening, and the inner wall of the opening. Thus, the accuracy of the shape of the opening is high, and the sealing property can be ensured.

  According to the second aspect of the present invention, the opening cutting blade has a narrow and narrow shape, is slidable in and out of the cavity, and rotates along the inner peripheral surface of the inner wall of the opening so that the inner side of the opening. This is a method for forming an opening of a blow molded product for excising the parison.

  According to the second aspect of the present invention, the opening cutting blade is narrow and elongated, is slidable in and out of the cavity, and rotates along the inner peripheral surface of the inner wall of the opening so as to be inside the opening. Excise the parison. For this reason, the parison closely adhered to the opening outer wall molding portion can be easily cut by the elongated opening cutting blade, and the parison does not adhere to the opening cutting blade.

  The present invention of claim 3 is the same circle as the inner periphery of the opening that is slidable in and out of the cavity inside the opening that is inserted almost entirely around the cut opening, and the opening cutting blade rotates. A cylindrical opening all-around blade having a circumference is provided, and after the parison is cut by the opening cutting blade, the opening all-around blade is slid and inserted into substantially the entire circumference of the cut portion of the parison, and the parison is cooled. This is a method for forming an opening of a blow molded product.

  In the present invention of claim 3, the same circle as the inner periphery of the opening that is slidable in and out of the cavity inside the opening that is inserted almost entirely around the cut opening and the opening cutting blade rotates. A cylindrical opening all-around blade having a circumference is provided, and after the parison is cut by the opening cutting blade, the opening all-around blade is slid and inserted into substantially the entire circumference of the cut portion of the parison, and the parison is cooled. . For this reason, the parison cut by the opening cutting blade does not weld again, the parison can be cooled without deforming the shape of the opening, and the cut parison can be easily taken out.

  According to the present invention of claim 4, a plurality of opening cutting blades that are narrow and elongated are provided, the length of the cutting blade tip is different, and the parison is arranged in order from the long blade at the cutting blade tip to the short blade. This is an opening forming method for a blow-molded product in which the parison inside the opening is cut off by being entered.

  In the present invention of claim 4, a plurality of opening cutting blades that are narrow and elongated are provided, the length of the cutting blade tip is different, and the parison is arranged in order from the long blade at the cutting blade tip to the short blade. Make an entry and cut the parison inside the opening. For this reason, a plurality of narrow and elongated opening cutting blades are sequentially inserted into the parison, so the parison is cut smoothly, the opening is not deformed, the dimensional accuracy is high, and the sealing property is also ensured it can.

  According to the fifth aspect of the present invention, the opening cutting blade has a narrow and narrow width, is slidable substantially perpendicular to the inner wall of the opening, and enters the parison at the tip of the inner wall of the opening, and then the inner wall of the opening. This is a method for forming an opening of a blow molded article that rotates along the inner peripheral surface of the tip of the part and cuts out the parison inside the opening.

  According to the present invention of claim 5, the opening cutting blade is narrow and elongated, is slidable at a substantially right angle with respect to the opening inner wall, and enters the parison at the tip of the opening inner wall, and then the opening inner wall. The parison inside the opening is cut off by rotating along the inner peripheral surface of the tip of the section. For this reason, the front end of the inner wall portion of the opening is uniformly formed, and there is no protrusion protruding from the front end of the inner wall portion of the opening toward the center of the opening.

  The present invention of claim 6 is a blow molded product opening forming method in which the opening cutting blade is formed in a cylindrical shape having an outer diameter that is the same as or slightly smaller than the inner diameter of the inner wall of the opening.

  In the present invention of claim 6, since the opening cutting blade is formed in a cylindrical shape having an outer diameter that is the same as or slightly smaller than the inner diameter of the opening inner wall portion, the opening cutting blade comes close to the opening inner wall portion by sliding the opening cutting blade. In the part, the part corresponding to the opening of the parison can be excised.

  The present invention of claim 7 is a method for forming an opening of a blow-molded product, wherein the opening cutting blade has a cylindrical tip having an outer diameter that is the same as or slightly smaller than the inner diameter of the inner wall of the opening. .

  In the seventh aspect of the present invention, the opening cutting blade has a cylindrical tip having an outer diameter that is the same as or slightly smaller than the inner diameter of the inner wall of the opening formed in a plurality of chevron shapes, so the parison is cut off by the opening cutting blade. Sometimes, the tip of the cutting edge of the opening cutting blade formed in a plurality of chevron shapes can bite in multiple locations of the parison, making it easier to cut the parison, less deformation of the parison, and making the melted parison into a uniform circle Can be excised.

  According to the eighth aspect of the present invention, there is provided a blow molded product in which a groove portion for forming a screw portion is formed on an outer surface of an opening outer wall portion of a blow molding die in a portion forming the opening outer wall portion of the opening outer wall forming portion. This is an opening forming method.

  In the eighth aspect of the present invention, a groove portion for forming a screw portion on the outer surface of the opening outer wall portion of the blow molding die is formed in a portion of the opening outer wall forming portion forming the opening outer wall portion. For this reason, a screw part can be formed in the outer surface of an opening outer wall part simultaneously with blow molding, and a lid etc. can be easily attached to an opening part.

  In the present invention, the blow molding die is provided with the opening outer wall forming portion that forms the opening outer wall portion, the opening upper wall portion, and the opening inner wall portion in the portion corresponding to the opening portion of the blow molded product. By opening the parison at the time of molding and closely contacting the opening outer wall forming portion of the blow molding die, the opening outer wall portion, the opening upper wall portion and the opening inner wall portion of the opening portion can be formed simultaneously.

  At the time of blow molding, the opening cutting blade was slid, and the parison inside the opening close to the inner wall of the opening of the parison was cut off at the tip of the cutting blade, so the opening cutting blade was held while holding the parison with the blow molding die. With this slide, the portion corresponding to the opening of the parison can be cut off at the tip of the cutting blade, leaving the inner wall of the opening.

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 with a narrow width | variety of the opening inner wall part of the blow molded product which is embodiment of this invention. It is sectional drawing of the opening part where the width | variety of the opening inner wall part of the blow molded product which is other embodiment of this invention is still narrower. It is sectional drawing of the part which forms the opening part of the receiving blow molding die used for the 1st Embodiment of this invention, an opening part cutting blade retreats rather than the front end surface of a receiving block, and a parison becomes a cavity. It is sectional drawing of the state before closely_contact | adhering. It is sectional drawing of the part which forms the opening part of the receiving blow molding die used for the 1st Embodiment of this invention, an opening part cutting blade retreats rather than the front end surface of a receiving block, and a parison becomes a cavity. FIG. 3 is a cross-sectional view showing a state where the blow pins are in close contact with each other and are inserted into a parison. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 1st Embodiment of this invention, and the cutting-blade front-end | tip part of an opening part cutting blade is inside a cavity from the front end surface of a receiving block. It is sectional drawing of the state which approached. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 1st Embodiment of this invention, and the cutting-blade front-end | tip part of an opening part cutting blade is inside a cavity from the front end surface of a receiving block. It is sectional drawing of the state which approached and rotated and excised the part corresponding to the inner side of the opening part of a parison. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 1st Embodiment of this invention, The state which the opening part perimeter blade of the parison entered into the part which the opening part cutting blade cut | disconnected It is sectional drawing of It is sectional drawing of the part which forms the opening part of the blow molding die used for the 1st Embodiment of this invention, and an opening part cutting blade, an opening part perimeter blade, and a blow pin respond | correspond to the inner side of the opening part of a parison It is sectional drawing of the state which retracted to the part of the front end surface of a receiving block after excising the part to perform. It is sectional drawing of the part of the opening part cutting blade of the blow molding die used for the 1st Embodiment of this invention, the opening part cutting blade advanced from the front end surface of the receiving block, and entered the inside of a parison. It is sectional drawing of a state. It is the figure seen from the front end side of the opening part perimeter blade of the part of the opening part cutting blade of the blow molding die used for the 1st embodiment of the present invention, and sees the blow molding die in Drawing 11 from the lower part. FIG. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 2nd Embodiment of this invention, and two opening part cutting blades retreat from the front end surface of a receiving block, and a parison is a cabinet. It is sectional drawing of the state closely_contact | adhered to the tee. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 2nd Embodiment of this invention, and sectional drawing of the state in which the two opening part cutting blades and the blow pin were inserted in the parison It is. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 3rd Embodiment of this invention, an opening part cutting blade retreats from the inner surface of an inner wall part of an opening part, and a parison becomes a cavity. It is sectional drawing of the state which contact | adhered. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 3rd Embodiment of this invention, and is sectional drawing of the state which the opening part cutting blade approached the front-end | tip of the opening part inner wall part. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 3rd Embodiment of this invention, and an opening part cutting blade approachs the front-end | tip of an opening inner wall part, and rotates and it is opening of a parison It is sectional drawing of the state which excised the part corresponding to the inner side of a part. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 4th Embodiment of this invention, A cylindrical opening part cutting blade retreats from the front end surface of a receiving block, and a parison is a cabinet. It is sectional drawing of the state closely_contact | adhered to the tee. It is sectional drawing of the part which forms the opening part of the blow molding die used for the 4th Embodiment of this invention, and a cylindrical opening part cutting blade is a cavity from the front end surface of a receiving blade with a cutting blade front end part It is sectional drawing of the state which approached into the inside. It is sectional drawing of the cutting-blade front-end | tip part of the opening part cutting blade used for the 4th 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 the 4th 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 the 4th 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.

  The opening structure of a blow molded product and its forming method 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 then a method of forming the opening of the 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 three 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 FIGS. 5-12, about the formation method of the opening part of the blow molded product which is the 1st Embodiment of this invention, formation of the tank opening part 10 of the fuel tank for motor vehicles which is a blow molded product The method will be described as an example. The second to fourth embodiments of the present invention will be described later.
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. The opening outer wall portion 15, the opening upper wall portion 13, and the opening inner wall forming portion 25 forming the opening inner wall portion 11 are 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. In the slide space 24, an elongated opening cutting blade 27 and a cylindrical opening full peripheral blade 28 having the same circumference as the circle around which the opening cutting blade 27 rotates are attached so that the side surface of the receiving block 22 can slide. It has been. A blow pin 23 is slidably attached to the center of the receiving block 22.

  When the parison 5 is sandwiched inside the blow molding die 20, as shown in FIG. 6, the blow pin 23 slides and enters the parison 5, and air is blown into the parison 5 to blow. When blow is performed, the parison 5 is in close contact with the cavity surface 26 of the blow molding die 20, and in close contact with the bottom surface of the opening outer wall forming portion 25 and the receiving block 22 in the tank opening 10 portion. Therefore, the opening outer wall 15, the opening upper wall 13, and the opening inner wall 11 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. 7, the opening cutting blade 27 is slid in the slide space 24 in the direction in the cavity (downward in FIG. 7).
As shown in FIGS. 5 to 10, the opening cutting blade 27 has an elongated cutting blade tip 27 b and a cutting blade cylinder 27 a that slides the cutting blade tip 27 b. When the opening cutting blade 27 is slid by the cutting blade cylinder 27 a after the parison 5 is brought into close contact with the opening outer wall molding portion 25, the cutting blade tip 27 b breaks through the parison 5. At this time, the opening part perimeter blade 28 does not slide and is positioned without contacting the parison 5.

At this time, as shown in FIG. 11, the tip of the cutting blade tip 27 b is located at a position (downward in FIG. 11) that has broken through the parison 5 held by the receiving block 22.
And as shown in FIG. 12, the cutting blade front-end | tip part 27b is located in the cut | interruption of the perimeter blade front-end | tip part 28b.

  Next, as shown in FIG. 8, the opening cutting blade 27 is rotated so that the cutting blade tip 27b is in close contact with the receiving block 22 of the parison 5, that is, the opening inner wall portion of the opening outer wall molding portion 25. 11, an inner portion forming the tank opening 10 is cut out from a portion close to the portion 11. Since the parison 5 is held by the receiving block 22 of the blow molding die 20, the parison 5 is less deformed, and the rotation of the opening cutting blade 27 causes the cutting blade tip 27 b to move inside the tank opening 10 of the parison 5. The corresponding part can be excised. At this time, the opening full circumference blade 28 rotates together with the opening cutting blade 27. The entire peripheral blade tip 28b also rotates as the cutting blade tip 27b rotates. However, since the entire peripheral blade tip 28b does not contact the parison 5, the tank opening 10 is not deformed.

If it does so, the part hold | maintained at the receiving block 22 of the parison 5 will be cut | disconnected in a disk shape part by the parison cutting part 5a.
In addition, at this time, it can be set as a parison connection part, leaving a part of parison cutting part. In this case, as will be described later, when the fuel tank 1 which is a blow molded product is taken out from the blow mold 20, the cut parison 5 is taken out from the blow mold 20 together with the fuel tank 1. Can do.

  Next, as shown in FIG. 9, the all-round blade cylinder 28 a is slid to insert the all-round blade tip 28 b into the cut portion of the parison 5 cut by the cutting blade tip 27 b. As shown in FIG. 12, since the entire peripheral blade tip 28b is formed in a full arc shape other than the narrow cutting blade tip 27b, the cutting edge of the parison 5 cut by the cutting blade tip 27b is formed. The all-round blade tip 28b can be inserted all around. For this reason, it can prevent that the cut | disconnected parison 5 fuse | melts again.

Then, the parison 5 is cooled, and as shown in FIG. 10, the cutting blade tip portion 27 b and the entire peripheral blade tip portion 28 b are moved backward (upward in FIG. 10) toward the blow molding die 20.
Thereafter, the blow molding die 20 is opened, the fuel tank 1 is taken out from the blow molding die 20, and the parison 5 inside the cut tank opening 10 is taken out from the blow molding die 20.

  When the parison connecting portion is provided, after the fuel tank 1 is taken out from the blow mold 20, the parison connecting portion is cut and the parison 5 in the tank opening 10 is taken out from the tank body outer wall 2. For this reason, the cut parison 5 does not fall into the fuel tank 1, and the cut parison 5 can be reliably taken out of the fuel tank 1.

  Next, based on FIG. 13 to FIG. 14, the formation of the opening 10 of the blow molded product according to the second embodiment of the present invention will be described. The method will be described as an example. In the second embodiment of the present invention, the shape of the opening cutting blade 27 is different, and the point not using the opening circumferential blade 28 is different from the first embodiment. Description of similar parts is omitted.

  The opening cutting blade 27 has a cutting blade cylinder 27a that slides in the slide space 24 of the blow molding die 20 and a cutting blade tip 27b that is arranged in a circular arc shape at the tip of the cutting blade cylinder 27a. And the some cutting blade front-end | tip part 27b is located in a line from the longest one to the shortest one.

  When the parison 5 is sandwiched inside the blow molding die 20, as shown in FIG. 13, the blow pin 23 slides and enters the parison 5, and air is blown into the parison 5 for blowing. When blow is performed, the parison 5 is in close contact with the cavity surface 26 of the blow molding die 20, and in close contact with the bottom surface of the opening outer wall forming portion 25 and the receiving block 22 in the tank opening 10 portion. Therefore, the opening outer wall 15, the opening upper wall 13, and the opening inner wall 11 of the tank opening 10 can be formed at the opening outer wall forming portion 25.

Next, as shown in FIG. 14, the opening cutting blade 27 is slid in the slide space 24 in the direction in the cavity (downward in FIG. 14).
As shown in FIGS. 13 and 14, the opening cutting blade 27 is formed with different lengths of the cutting blade tip 27b, so when the cutting blade tip 27b is slid with the cutting blade cylinder 27a, The long cutting blade tip 27b enters the parison 5 slightly, and the opening cutting blade 27 continues to enter gradually while rotating.

  In this case, since the cutting blade tip 27b of the plurality of narrow and long opening cutting blades 27 is inserted into the parison 5 while rotating in order, the parison 5 is smoothly cut, and the tank opening The portion 10 is not deformed, the dimensional accuracy is high, and the sealing performance can be secured.

  Next, based on FIGS. 15 to 17, a method for forming an opening of a blow molded product according to the third embodiment of the present invention is described. Formation of a tank opening 10 of an automotive fuel tank that is a blow molded product The method will be described as an example. The third embodiment of the present invention is different from the first embodiment in that the shape of the opening cutting blade 27 and the cutting portion of the parison 5 are different, and the opening circumferential blade 28 is not used. The point will be described, and the description of the same part will be omitted.

  As shown in FIG. 15, the opening cutting blade 27 is formed to be narrow and long and to be slidable substantially at right angles to the inner wall 11 of the opening. And the cutting blade front-end | tip part 27b of the opening part cutting blade 27 is slid by the cutting blade cylinder 27a so that it may approach into the continuous part with the parison 5 of the front-end | tip part of the opening part inner wall part 11. FIG.

  When the parison 5 is sandwiched inside the blow molding die 20, as shown in FIG. 13, the blow pin 23 slides and enters the parison 5, and air is blown into the parison 5 for blowing. When blow is performed, the parison 5 is in close contact with the cavity surface 26 of the blow molding die 20, and in close contact with the bottom surface of the opening outer wall forming portion 25 and the receiving block 22 in the tank opening 10 portion. Therefore, the opening outer wall 15, the opening upper wall 13, and the opening inner wall 11 of the tank opening 10 can be formed at the opening outer wall forming portion 25.

  Next, as shown in FIG. 16, in the slide space 24, the cutting blade tip 27b of the opening cutting blade 27 is connected to the parison 5 at the tip of the opening inner wall 11 (left direction in FIG. 16). Slide to. Thereafter, as shown in FIG. 17, the cutting blade tip 27b of the opening cutting blade 27 is rotated.

  As a result, the parison 5 and the opening inner wall 11 held by the receiving block 22 are cut. The front end of the opening inner wall portion 11 is uniformly formed on the same plane without unevenness by the opening cutting blade 27, and a protrusion protruding from the front end of the opening inner wall portion 11 toward the center of the tank opening portion 10. Therefore, the shape of the tank opening 10 is smooth.

  Next, based on FIGS. 18-22, about the formation method of the opening part of the blow molded product which is the 4th Embodiment of this invention, formation of the tank opening part 10 of the fuel tank for motor vehicles which is a blow molded product The method will be described as an example. In the fourth embodiment of the present invention, the shape of the opening cutting blade 27 is different, and the point not using the opening circumferential blade 28 is different from the first embodiment. Description of similar parts is omitted.

  As shown in FIG. 18, the opening cutting blade 27 is formed such that the cutting blade cylinder 27 a extends in the blow molding die 20 upward in FIG. 18, and the cutting blade tip portion 27 b is the inner diameter of the opening inner wall portion 11. Are formed in a cylindrical shape having substantially the same outer diameter. In this case, as shown in FIG. 19, the tank opening 10 of the parison 5 is cut by the cutting blade tip 27b at a portion close to the opening inner wall 11 by sliding of the cutting blade cylinder 27a of the opening cutting blade 27. The part corresponding to can be excised.

As shown in FIG. 20, the tip of the cutting blade tip 27b can be formed in a smooth arc shape with no irregularities.
Further, as shown in FIGS. 21 and 22, the cutting blade tip 27b of the opening cutting blade 27 has a cylindrical tip having an outer diameter substantially the same as the inner diameter of the opening inner wall 11 formed into a plurality of chevron shapes. Can do. The number of the plurality of chevron shapes can be arbitrarily set. In this case, when the parison 5 is excised with the cutting blade tip portion 27b, the cutting edges of the cutting blade tip portions 27b formed in a plurality of chevron shapes can bite at a plurality of locations of the parison 5, and the parison 5 is excised. It is easy, the deformation of the parison 5 is small, and the melted parison 5 can be cut into a uniform circle.

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 27 Opening part cutting blade 27b Cutting blade front-end | tip Part

Claims (8)

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 mold is provided with an opening outer wall forming portion that forms the opening outer wall portion, the opening upper wall portion, and the opening inner wall portion in a portion corresponding to the opening portion of the blow molded product, and Provided with an opening cutting blade that can slide on the inside or outside of the cavity or the parison inside the opening than the inner wall of the opening,
At the time of blow molding, after closely attaching the parison to the opening outer wall molding part,
An opening forming method for a blow-molded product, wherein the opening cutting blade is slid, and the parison inside the opening adjacent to the opening inner wall of the parison is cut off at the tip of the cutting blade. .   The opening cutting blade is narrow and elongated, is slidable in and out of the cavity, and rotates along the inner peripheral surface of the inner wall of the opening to cut out a parison inside the opening. The blow-molded product opening forming method according to claim 1.   A cylinder that is slidable in and out of a cavity inside the opening that is inserted in substantially the entire circumference of the cut opening, and that has the same circumference as the inner periphery of the opening where the opening cutting blade rotates. After the parison is cut by the opening cutting blade, the opening full circumference blade is slid and inserted into substantially the entire circumference of the cut portion of the parison, and the parison is cooled. The blow-molded product opening forming method according to claim 2.   A plurality of opening cutting blades having a narrow width and a long width are provided, the length of the cutting blade tip portion is different, and the opening is made to enter the parison in the order of a long blade from the cutting blade tip portion to a short blade. The blow-molded product opening forming method according to claim 2, wherein a parison inside the portion is cut out.   The opening cutting blade is narrow and elongated, is slidable substantially perpendicular to the inner wall of the opening, and enters the parison at the tip of the inner wall of the opening, and then the tip of the inner wall of the opening. The blow-molded product opening forming method according to claim 1, wherein the parison inside the opening is cut off by rotating along an inner peripheral surface of the blow-molded product.   2. The blow-molded product opening forming method according to claim 1, wherein the opening cutting blade is formed in a cylindrical shape having an outer diameter that is the same as or slightly smaller than the inner diameter of the opening inner wall.   The blow-molded product opening forming method according to claim 6, wherein the opening cutting blade has a cylindrical tip having an outer diameter substantially the same as the inner diameter of the opening inner wall.   The groove part which forms a screw part in the outer surface of the said opening part outer wall part of the said blow molding metal mold | die was formed in the part which forms the said opening part outer wall part of the said opening part outer wall shaping | molding part. The method for forming an opening of a blow molded product according to any one of the above.