JP2015030115A - Method for 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 the opening part of a synthetic resin-made blow molded article to be formed within a blow molding mold. The blow molding mold 20 comprises: a slender slidable opening part-cutting blade 27 rotating along the opening part for cutting it; and a slidable cylindrical opening part-cutting circumferential blade 28 having the same circumference as that of rotation of the blade 27. In a blow molding process, a parison 5 is closely contacted with an opening part outer wall molding part 25, and the blade 27 is made to slide. After that, a top 27b of the cutting blade is rotated along the opening part to cut the parison by the blade 27. The opening part-cutting circumferential blade 28 is slidingly inserted in the cut part of the parison 5, and the parison 5 is cooled to take the parison 5 of the cut opening out of the blow molded article.

Description

  The present invention relates to a method for forming an opening 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 and extruded from a die of a blow molding machine. A blow molded product that is a hollow body was manufactured.

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. 18 to 20, 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 FIG. 18, 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 by blow molding. Blow molding is performed in a state of entering the mold surface of the mold 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. 19, the rotary blade 130 is rotated to cut out the cut portion 118 of the opening 110 to form the opening 110.

Then, as shown in FIG. 20, the cut portion 118 of the opening 110 in close contact with the blow molding die 120 is taken out from the blow molded product 101.
However, in this method, since the parison 5 cut by the blade edge 131 is in a semi-molten state, the cut portion 118 of the opening 110 and the cut surface of the opening wall 111 are fused again, and the opening 110 is formed. In some cases, the efficiency of the system decreased.

JP 2010-76297 A

  Therefore, an object of the present invention is to provide a method for forming a blow molded product that can easily form an opening in a blow mold even in a blow molded product such as a fuel tank.

The present invention of claim 1 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. The upper wall of the opening extending to
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. Provided with an elongated opening cutting blade that is slidable inside and outside the cavity and that rotates along the inside periphery of the opening to cut the inside of the opening,
Cylindrical opening having the same circumference as the inside of the opening that can slide inside and outside of the cavity inside the opening that is inserted around the entire circumference of the cut opening and the opening cutting blade rotates. Provide a full circumference blade,
At the time of blow molding, after closely attaching the parison to the opening outer wall molding part,
After sliding the opening cutting blade and inserting the cutting blade tip into the inner part of the opening of the parison, rotate the cutting blade tip along the inner periphery of the opening to make the parison into the opening cutting blade. , Slide and insert the entire circumference of the opening into the entire circumference of the cut part of the parison, cool the parison,
A blow molded product opening forming method, wherein a blow molded product is taken out from a blow molding die, and a parison inside a cut opening is taken out from the blow molded product.

  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. The upper wall portion of the opening portion is integrally extended in the center direction of the opening portion. Therefore, the outer wall portion of the opening and the upper wall portion of the opening can be formed simultaneously with the blow molding, and a screw portion or the like can be provided on the outer wall portion of the opening to attach a lid or the like that closes the opening. 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 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.

  An elongated opening cutting blade that is slidable inside and outside of the cavity and that rotates along the inner periphery of the opening to cut the opening is provided on the inner side of the opening than the outer wall forming portion of the opening. . For this reason, at the time of blow molding, the opening cutting blade is slid with respect to the parison in close contact with the blow molding die, and then rotated along the inner periphery of the opening, thereby corresponding to the inside of the opening of the parison. The part can be excised.

  Cylindrical opening having the same circumference as the inside of the opening that can slide inside and outside of the cavity inside the opening that is inserted around the entire circumference of the cut opening and the opening cutting blade rotates. An all-round blade was provided. For this reason, it is possible to prevent the parison from being fused again by inserting the entire circumferential edge of the opening over substantially the entire circumference of the cut portion of the parison cut by the opening section cutting blade. Further, since the opening is less deformed by the entire circumference of the opening and the dimensional accuracy of the opening can be improved, post-processing is not necessary.

  At the time of blow molding, after the parison is brought into close contact with the outer wall forming part of the opening, the opening cutting blade is slid, the tip of the cutting blade is inserted into the inner part of the opening of the parison, and then the cutting blade along the opening. The tip is rotated and the parison is cut with an opening cutting blade. 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 opening full circumference blade is slid and inserted into almost the entire circumference of the parison cutting part, and the parison is cooled, so the parison cut by the opening cutting blade does not weld again, and the shape of the opening also changes. Without cooling the parison.
Since the blow molded product is taken out from the blow mold and the parison inside the cut opening is taken out from the blow molded product, the parison in the cut opening can be surely taken out from the blow molded product.

  In the present invention of claim 2, the parison is cut by the rotation of the opening cutting blade inside the opening. The parison to be cut is connected to a part of the opening from the blow mold. This is a method for forming an opening of a blow-molded product, in which, after taking out, the connecting portion is cut and the parison inside the opening is taken out from the blow-molded product.

  In the present invention of claim 2, the parison is cut by the rotation of the opening cutting blade inside the opening, and the blow molded product is removed from the blow mold while the parison to be cut and a part of the opening are connected. After taking out, a connection part is cut | disconnected and the parison inside an opening part is taken out from a blow molded product. For this reason, the cut parison does not fall into the blow molded product, and the parison inside the cut opening can be taken out of the blow molded product.

  According to a third aspect of the present invention, when blow molding is performed, an opening is formed in a blow molded product in which a blow pin is inserted into a portion of a parison to be cut inside the opening to blow and air for blow molding is blown. Is the method.

  According to the third aspect of the present invention, during blow molding, since the blow pin is inserted into the portion of the parison to be cut inside the opening to form the opening and blow molding air is blown, the blow pin marks are cut. It remains in the portion of the parison to be blown, and there is no trace of the blow pin on the blow molded product, so that airtightness of the blow molded product can be secured.

  The present invention of claim 4 is a blow molded product opening forming method in which a blow molding die on the tip side of the cutting blade tip is provided with an openable and closable lid that faces the parison.

  In the present invention of claim 4, since the openable and closable lid portion facing the parison is formed on the blow molding die on the tip side of the cutting blade tip portion, from the opening portion of the blow molding die on which the opening cutting blade slides, The parison does not enter, and the sliding of the opening cutting blade is not hindered.

  According to a fifth aspect of the present invention, there is provided a blow-molded product opening in which a groove forming a screw portion is formed on an outer surface of the blow-molded product outer wall in a portion of the blow-molded die that forms the opening outer wall. It is a forming method.

  In the fifth aspect of the present invention, the groove forming the screw portion is formed on the outer surface of the opening outer wall portion of the blow molded product in the portion forming the opening outer wall portion of the blow molding die. A screw part can be formed in the outer surface of a part outer wall part, and a lid | cover etc. can be easily attached to an opening part.

  According to the sixth aspect of the present invention, a receiving block is provided at a portion corresponding to the inside of the opening portion of the blow molding die, and the opening cutting blade rotates around the outer periphery of the receiving block, and the front end surface of the receiving block. This is an opening forming method for a blow molded product in which the parison cut off by the opening cutting blade is in close contact, and the parison in close contact with the front end surface of the receiving block is removed after blow molding.

  According to the sixth aspect of the present invention, a receiving block is provided at a portion corresponding to the inside of the opening of the blow molding die, and the opening cutting blade rotates around the outer periphery of the receiving block, and on the front end surface of the receiving block. The parison cut off by the opening 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 to be cut is closely attached to the block, making it easy to cut the parison with the opening cutting blade, and holding the parison cut with the opening cutting blade securely, It can be reliably removed from the blow molded product.

  An elongated opening cutting blade that is slidable inside and outside of the cavity inside the opening rather than the outer wall forming part of the opening and that rotates along the inner periphery of the opening to cut the inside of the opening. Therefore, during blow molding, by sliding the opening cutting blade against the parison in close contact with the blow mold, and then rotating along the opening, the portion corresponding to the inside of the opening of the parison Can be excised.

  A cylindrical shape having the same circumference as the inside of the opening of the parison that can slide inside and outside of the cavity inside the opening that is inserted almost entirely around the cut opening and the opening cutting blade rotates. Since the opening all-around blade is provided, it is possible to prevent the parison from being fused again by inserting the opening all-around blade over substantially the entire circumference of the cut portion of the parison cut by the opening cutting blade.

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 part which forms the opening part of the blow molding die used for embodiment of this invention, and an opening part cutting blade retreats rather than the front end surface of a receiving block, and a parison is closely_contact | adhered to a cavity. It is sectional drawing of a state. It is sectional drawing of the part which forms the opening part of the blow molding die used for embodiment of this invention, an opening part cutting blade retreats from the front end surface of a receiving block, a parison adheres to a cavity, and a blow pin It is sectional drawing of the state inserted in the parison. 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 state which the cutting blade front-end | tip part of the opening part cutting blade entered the inside of the cavity from the front end surface of the receiving block FIG. 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 rotates. It is sectional drawing of the state which cut off 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 embodiment of this invention, and sectional drawing of the state which the opening part perimeter blade of the parison entered into the part which the opening part cutting blade cut | disconnected Is 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 part by which an opening part cutting blade, an opening part perimeter blade, and a blow pin correspond to the inner side of the opening part of a parison is shown. It is sectional drawing of the state which retracted to the part of the front end surface of a block after excising. It is the bottom view of the part which forms the opening part of the blow molding die used for embodiment of this invention, and is the bottom view which looked at the blow molding die in FIG. It is sectional drawing of the part of the opening part cutting blade of the blow molding die used for embodiment of this invention, an opening part cutting blade retreats rather than the front end surface of a receiving block, and a parison is contact | adhered to a cavity. It is sectional drawing. 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 embodiment of this invention, and is the bottom view which looked at the blow molding die in FIG. It is. It is sectional drawing of the part of the opening part cutting blade of the blow molding die used for embodiment of this invention, and the cross section of the state which the opening part cutting blade advanced from the front end surface of the receiving block, and entered the inside of a parison FIG. 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 embodiment of this invention, and is the bottom view which looked at the blow molding die in FIG. It is. It is the bottom view of the part which shows rotation of the opening part cutting blade of the blow molding die used for embodiment of this invention, and is the bottom view which looked at the blow molding die in FIG. It is the figure seen from the front end side of the opening part perimeter blade of the part which shows the state which the opening part cutting blade of the blow molding die used for embodiment of this invention rotated leaving a part, FIG. It is the bottom view which looked at the shaping die from the lower part. It is sectional drawing of the part of the opening part cutting blade of the blow molding die used for embodiment of this invention, an opening part cutting blade retreats from the front end surface of a receiving block, and the lid | cover of an opening part cutting blade is a parison. It is sectional drawing of the state provided between the opening part cutting blades. It is the figure seen from the front end side of the opening part perimeter blade of the part of the cover of the opening part cutting blade of the blow molding die used for an embodiment of the present invention, and it looked at the blow molding die in Drawing 16 from the lower part. It is a bottom view. 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.

  A method for forming a blow molded product according to an embodiment of the present invention will be described with reference to FIGS. First, an opening structure of an automobile fuel tank will be described with reference to FIGS. 1 and 2, 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. FIG. 2 is a cross-sectional view of the tank opening 10 according to the embodiment of the present 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.

Next, based on FIG. 3 to FIG. 17, the method for forming the opening 10 of the blow molded product according to the embodiment of the present invention is an example of the method for forming the tank opening 10 of the automobile fuel tank that is the blow molded product. 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. 3, 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. 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. 4, the blow pin 23 slides and enters the parison 5, blows air into the parison 5, and blows. 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.

At this time, as shown in FIG. 10, the tip of the cutting blade tip 27 b is located at a position (upward in FIG. 10) retreated from the parison 5 held by the receiving block 22.
And as shown in FIG. 11, the cutting blade front-end | tip part 27b is located in the cut | interruption of the perimeter blade front-end | tip part 28b.

  As shown in FIGS. 16 and 17, an openable / closable lid portion 27 c that faces the parison 5 is formed in the opening portion of the receiving block 22 on which the opening cutting blade 27 on the tip side of the cutting blade tip portion 27 b slides. be able to. In this case, the parison 5 does not enter from the opening where the opening cutting blade 27 slides, and the sliding of the opening cutting blade 27 is not hindered.

Next, as shown in FIG. 5, the opening cutting blade 27 is slid in the slide space 24 in the direction in the cavity (downward in FIG. 5).
As shown in FIGS. 9 to 16, the opening cutting blade 27 has an elongated cutting blade tip 27b and a cutting blade cylinder 27a that slides the cutting blade tip 27b. 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 forming 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. 12, the tip of the cutting blade tip 27 b is located at a position (upward in FIG. 10) that has broken through the parison 5 held by the receiving block 22.
And as shown in FIG. 13, 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. 6, the opening cutting blade 27 is rotated so that the cutting blade tip 27 b comes into close contact with the receiving block 22 of the parison 5, that is, from the portion close to the opening outer wall molding portion 25. Then, the inner part forming the tank opening 10 is cut off. 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.

Then, as shown in FIG. 14, the part held by the receiving block 22 of the parison 5 is cut into a disk shape by the parison cutting part 5a.
At this time, as shown in FIG. 15, a part of the parison cutting portion 5a can be left to form a parison connecting portion 5b. 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. 7, the entire peripheral blade tip 28 b is inserted into the cut portion of the parison 5 cut by the cutting blade front end portion 27 b by sliding the entire peripheral blade cylinder 28 a. As shown in FIG. 9, 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. 8, the cutting blade tip portion 27b and the entire peripheral blade tip portion 28b are moved backward (upward in FIG. 8) 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.

  In the case of having the parison connecting portion 5b, after the fuel tank 1 is taken out from the blow mold 20, the parison connecting portion 5b 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.

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Tank main body outer wall 10 Tank opening part 20 Blow molding die 22 Receiving block 27 Opening part cutting blade 27b Cutting blade front-end | tip part 28 Opening part perimeter blade 28b Whole perimeter edge | tip part

Claims (6)

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 upper wall portion of the opening that is integrally extended in the center direction of the
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 inside the opening is an elongated opening cutting blade that is slidable in and out of the cavity and that rotates along the periphery of the inside of the opening to cut the inside of the opening,
A cylinder that is slidable in and out of a cavity inside the opening that is inserted almost entirely around the cut opening, and that has the same circumference as the inside of the opening around which the opening cutting blade rotates. Provided with a circular opening all around the blade,
At the time of blow molding, after closely attaching the parison to the opening outer wall molding part,
After sliding the opening cutting blade and inserting the cutting blade tip into the inner part of the opening of the parison, rotating the cutting blade tip along the inner periphery of the opening, The parison is cut with the opening cutting blade, and the opening full circumference blade is slid and inserted into substantially the entire circumference of the parison cutting portion, the parison is cooled,
A method for forming an opening of a blow-molded product, wherein the blow-molded product is taken out from the blow-molding die, and a parison inside the cut opening is removed from the blow-molded product.   The parison is cut by rotating the opening cutting blade inside the opening, and the blow molded product is taken out from the blow mold in a state where the parison to be cut and a part of the opening are connected. 2. The blow molding product opening forming method according to claim 1, wherein the connecting portion is cut and the parison inside the opening is taken out of the blow molding product.   The blow according to claim 1 or 2, wherein a blow pin is inserted into a portion of the parison to be cut inside the opening to blow the air for blow molding during the blow molding. Method for forming opening of molded product.   The blow-molded product opening formation according to any one of claims 1 to 3, wherein an openable and closable lid is formed on the blow-molding die on the tip side of the cutting blade tip. Method.   The groove part which forms a thread part in the outer surface of the said opening outer wall part of the said blow molding goods was formed in the part which forms the said opening outer wall part of the said blow molding metal mold | die. The method for forming an opening of a blow molded article according to one item.   A receiving block is provided in a portion corresponding to the inside of the opening of the blow molding die, and the opening cutting blade rotates on the outer periphery of the receiving block, and the opening is formed on the front end surface of the receiving block. 6. The blow-molded product opening formation according to claim 1, wherein the parison cut out by the cutting blade is in close contact, and the parison that is in close contact with the front end surface of the receiving block is removed after blow molding. Method.