JP2015071253A - Opening part formation method of blow molding product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an opening part molding device of a blow molding product in which an opening part can be formed easily and quickly in a blow molding metal mold even in a case of a blow molding product such as a fuel tank.SOLUTION: In an opening part formation device of a blow molding product, an opening part 10 includes an opening tubular part and an opening cutting part 18. At a blow molding metal mold 20, an opening tubular part molding part 25 and a cutting part holding part 22 are provided, an opening part cutting blade 27 for cutting the opening cutting part 18 is provided, and a tubular opening part whole circle blade 28 having a same circle as the inside periphery of an opening part in which the opening part cutting blade 27 rotates is provided. At the opening part whole circle blade 28, formed is an opening part whole circle blade gap part 28c in which at least one place of opening part cutting blades 27 slides, the tip surface of the opening part whole circle blade 28 forms an opening part whole circle blade protruding part 28d and an opening part whole circle blade receding part 28e, and formed is an opening part whole circle blade inclined surface part 28f which is obliquely inclined so that the opening part whole circle blade protruding part 28d and the opening part whole circle blade receding part 28e are jointed to each other.

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, the parison of the molten thermoplastic synthetic resin member is formed into a cylindrical shape and extruded from a die of a blow molding machine, the parison is sandwiched between blow molding dies, air is blown into the parison, and an automobile fuel tank, etc. 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. 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 FIG. 14, the opening 110 is formed by forming a blade edge 133 at the tip of the rotary blade 130, slightly protruding the blade edge 133 into the cavity 126 and positioning the blade edge 131 in advance by a blow molding die. Blow molding is performed in a state of entering the inside of the mold surface of 120, and a resin parison is brought into close contact with the blade 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.

Then, as shown in FIG. 16, 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.

For this reason, it is considered that a cylindrical cutting blade is inserted separately from the cutting edge 131 for cutting so that the cutting surface does not weld to the entire circumference, but the cutting edge of the cylindrical cutting blade is cut off. As the cutting edge 131 rotates, it rotates while contacting the surface of the parison 5, and the cutting edge 131 to be cut off by friction becomes slow.

JP 2010-76297 A

  Therefore, an object of the present invention is to provide a blow molded product opening molding apparatus that can easily and quickly form an opening in a blow molding die even in a blow molded product such as a fuel tank.

The present invention of claim 1 is a synthetic resin blow-molded product opening forming apparatus for forming an opening of a molded product formed by blow molding in a blow mold.
The opening is formed by extending the outer wall of the blow-molded product and integrally bending the outer wall from the outer wall of the blow-molded product, and the opening that is cut from the opening tubular portion to form the opening. Having a resection,
The blow molding die is provided with an opening cylindrical part forming part that forms an opening cylindrical part and a cut part holding part that forms an opening cutting part at a part corresponding to the opening part of the blow molded product, and the opening cylindrical part. Provided with an elongated opening cutting blade that is slidable in and out of the cavity inside the opening rather than the molded part and that rotates along the inner periphery of the opening to cut the opening excision,
The entire cylindrical opening having the same circumference as the inner periphery of the opening that is inserted into substantially the entire circumference of the cut opening, can slide inside and outside the cavity, and the opening cutting blade rotates. A peripheral blade is provided, and the opening full circumference blade is formed with an opening full circumference blade gap portion in which at least one opening cutting blade slides,
The front end surface of the opening all-around blade forms an opening all-around blade protruding portion that protrudes in the axial direction across the opening all-around blade gap, and the other retreats in the axial direction. An opening all-around blade receding portion is formed, and an opening all-around blade inclined portion that is inclined obliquely so as to be continuous with the opening all-around blade extending portion and the opening all-around blade retracting portion is formed. It is the opening part formation apparatus of the blow molded product.

In the first aspect of the present invention, the opening portion extends from the outer wall of the blow molded product, and is formed by bending the outer wall integrally from the outer wall to the outside of the blow molded product, and the opening cylindrical portion. It has an opening excision part which is excised and forms an opening. For this reason, the opening cylindrical part and opening cut part of the same parison 5 opening part can be integrally formed from the outer wall of a blow molded product.

The blow molding die is provided with an open cylindrical part forming part for forming an open cylindrical part and a cut part holding part for forming an open cut part at a part corresponding to the opening part of the blow molded product. For this reason, the opening cylindrical part and opening cut part of an opening part can be formed simultaneously by inflating a parison at the time of blow molding, and making it closely_contact | adhere to an opening cylindrical part shaping | molding part and an opening cutting part.

The blow molding die is provided with an open cylindrical part forming part for forming an open cylindrical part and a cut part holding part for forming an open cut part at a part corresponding to the opening part of the blow molded product. For this reason, the opening cylindrical part of an opening part can be formed in a blow molding die at the same time as the blow molded product is formed, and the opening excision part can be cut out from the opening cylindrical part.

An elongated opening cutting blade that is slidable inside and outside of the cavity and that rotates along the periphery of the inside of the opening to cut the opening excision is provided on the inside of the opening than the formed part of the opening cylindrical part. . For this reason, the opening cutting blade can be rotated to cut out the opening cutting portion inside the opening.

The entire cylindrical opening having the same circumference as the inner periphery of the opening that is inserted into substantially the entire circumference of the cut opening, can slide inside and outside the cavity, and the opening cutting blade rotates. A peripheral blade was provided. For this reason, it is possible to prevent the parison from being re-welded by inserting the entire circumferential edge of the opening into the cut surface of the parison of the opening cut by the opening cutting blade.

Since the opening all-around blade is formed with an opening all-around blade gap that slides at least one opening cutting blade, the opening cutting blade and the opening all-around blade are located on the same circumference. Thus, the opening cutting blade and the opening full-circumference blade rotate simultaneously, and the opening full-cutting blade can be quickly inserted into the cutting surface of the parison as the opening cutting blade slides and rotates.

The front end surface of the opening all-around blade forms an opening all-around blade protruding portion that protrudes in the axial direction across the opening all-around blade gap, and the other retreats in the axial direction. An opening all-around blade receding part was formed, and an opening all-around blade inclined part inclined obliquely so that the opening all-around blade overhanging part and the opening all-around blade retracting part were continuous was formed.

For this reason, when the entire circumference blade of the opening is inserted into the cut surface of the parison, only the portion of the entire circumference of the opening contacts the parison, and the portion where the tip of the entire circumference of the opening contacts the parison is small. Thus, the friction between the parison and the entire circumferential edge of the opening is reduced, the rotation of the entire circumferential edge of the opening is accelerated, and the formation speed of the opening can be increased. Moreover, the force which rotates an opening part cutting blade and an opening part perimeter blade becomes small, the load to an installation is small, the maintenance frequency of an installation is reduced, and the apparatus to rotate can also be reduced in size.

A second aspect of the present invention is an apparatus for forming an opening of a blow molded product, in which a plurality of opening cutting blades are formed, and the entire circumferential edge of the opening is divided into a plurality of portions that are the same as the opening cutting blade.

In the second aspect of the present invention, a plurality of opening cutting blades are formed, and the entire circumferential edge of the opening is divided into the same plurality as the opening cutting blade, so the openings are formed by the plurality of opening cutting blades. It can be cut, the rotation angle of the opening cutting blade is reduced, the time for cutting the opening cutting portion of the opening is shortened, the parison to be cut is less deformed, and deformation of the opening can be prevented.

According to the third aspect of the present invention, the thickness of the inclined surface at the tip of the entire circumference of the opening is thicker on the side of the opening of the entire circumference of the opening, and gradually decreases toward the retracted portion of the entire circumference of the opening. It is the opening part formation apparatus of the blow molded product formed in this way.

In the third aspect of the present invention, the thickness of the inclined surface at the tip of the entire circumference of the opening is thicker on the side of the opening of the entire circumference of the opening, and gradually decreases in thickness toward the retracted portion of the entire circumference of the opening. As a result, the contact area between the entire circumferential edge of the opening and the parison can be reduced as a whole, and the load for rotating the entire circumferential edge of the opening can be reduced.

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

In the present invention of claim 4, since the blow pin is inserted into the part of the parison to be cut inside the opening to form the opening and blow molding air is blown at the time of blow molding, the mark of the blow pin is cut. It remains in the opening excision part which is a part of the parison, and the blow pin mark does not remain on the blow molded product, and the air tightness of the blow molded product can be secured.

According to the fifth aspect of the present invention, the portion corresponding to the opening cut portion of the blow molding die is provided with a cut portion holding portion, and the opening cutting blade rotates around the outer periphery of the cut portion holding portion and the cut portion is held. This is a blow molding product opening forming method in which an opening excision part cut out by an opening cutting blade is brought into close contact with the front end surface of the part, and the open excision part adhering to the front end surface of the excision holding part after blow molding is removed.

According to the fifth aspect of the present invention, a portion corresponding to the opening cut portion of the blow molding die is provided with a cut portion holding portion, and the opening cutting blade rotates around the outer periphery of the cut portion holding portion, and the cut portion is held. The opening excision part excised by the opening cutting blade comes into close contact with the distal end surface of the part, and the opening excision part adhering to the distal end face of the excision holding part is removed after blow molding. For this reason, the parison to be cut is brought into close contact with the excision holding part, and the parison is easily excised with the opening cutting blade, and the parison excised with the opening cutting blade is securely held and excised after blow molding. The parison can be securely removed from the blow molded product.

The front end surface of the opening all-around blade forms an opening all-around blade overhanging portion and an opening all-around blade retracting portion, and the opening all-around blade overhanging portion and the opening all-around blade retreating portion are continuous. An opening all-round blade slope portion inclined obliquely was formed. For this reason, when the opening all-around blade is inserted into the cutting surface of the parison, the portion where the tip of the opening all-around blade contacts the parison is reduced, and the friction between the parison and the opening all-around blade is reduced, The rotation of the entire circumference of the opening becomes faster, and the formation speed of the opening can be increased.

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 from the front end surface of a cutting part holding part, and a parison adheres to a cavity closely It is sectional drawing of the state. It is a cross-sectional view of the portion forming the opening of the blow molding mold used in the embodiment of the present invention, the opening cutting blade is retracted from the front end surface of the excision holding portion, the parison is in close contact with the cavity, It is sectional drawing of the state in which the blow pin was 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 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 cutting part holding part 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, 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 a bottom view of the opening part cutting blade and the opening part perimeter blade which form the opening part of the blow molding die used for embodiment of the present invention, and is the bottom view which looked at the blow molding die in Drawing 7 from the lower part. is there. It is a side view in which the opening part cutting blade which forms the opening part of the blow molding die used for embodiment of this invention is located in the opening part perimeter blade clearance gap of an opening part perimeter blade. It is a perspective view of the opening part perimeter blade of a blow molding die used for an embodiment of the invention. It is a bottom view of the opening part perimeter blade of a blow molding die used for an embodiment of the invention. It is sectional drawing of the front-end | tip part of the opening part perimeter blade of the blow molding die used for embodiment of this invention, and is a cross section along the AA line, BB line, and CC line in FIG. 11, respectively. FIG. It is an expanded sectional view of the front-end | tip part of the opening perimeter blade of the blow molding die used for embodiment of this invention, and each followed the AA line, the BB line, and CC line in FIG. It is sectional drawing. 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 blow molding product opening molding apparatus according to the embodiment of the present invention will be described with reference to FIGS. 1 to 13 by taking an automobile fuel tank forming apparatus as a blow molding product as an example. First, an opening structure of an automobile fuel tank will be described with reference to FIGS. 1 and 2, and then an apparatus for 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. 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, which are opening cylindrical portions. In the tank opening 10, when the insert member is embedded in the opening outer wall 15, the opening inner wall 11 can be omitted. On the inner side of the inner wall portion 11 of the opening portion, an opening cutting portion 18 to be described later that is cut to form an opening is provided.

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, by increasing the rigidity of the opening cylindrical portion 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, the thickness of the opening outer wall 15 is increased. Rigidity can be ensured without increasing the thickness. 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. 13, an apparatus for forming a tank opening 10 of a fuel tank for an automobile, which is a blow-molded product, as an apparatus for forming an opening of a blow-molded product according to an embodiment of the present invention. An example will be described.
The blow molding die 20 is usually molded in a cavity inside by sandwiching a synthetic resin parison 5 which is discharged in a molten state from a nozzle of a blow molding machine (not shown) located above the blow molding die 20. As shown in the figure, it is formed by a blow molding die main body 21 divided into left and right two parts.

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 tubular portion forming portion 25 that forms the opening outer wall portion 15 and the opening upper wall portion 13 of the 10 opening tubular portions 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 cylindrical portion molding portion 25 of the blow molding die main body 21, and a columnar cut portion is provided at the center thereof. The holding part 22 is fitted. The opening excision 18 is in close contact with the cavity surface 26 that is the cavity-side surface of the excision retainer 22.

A ring-shaped slide space 24 is formed between the cut-out holding part 22 and the blow molding die main 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 can slide on the side surface of the excision holding portion 22. Installed on. A blow pin 23 is slidably attached to the center of the cut portion holding portion 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 comes into close contact with the cavity surface 26 of the blow molding die 20, and in close contact with the bottom surface of the open tubular portion forming portion 25 and the cut portion holding portion 22 in the tank opening 10 portion. The parison 5 that is in close contact with the bottom surface of the excision holding part 22 is cut by the opening cutting blade 27 to become the opening excision 18. For this reason, the opening outer wall part 15, the opening upper wall part 13, and the opening inner wall part 11 of the tank opening part 10 can be formed at the part of the opening cylindrical part forming part 25.

In the portion of the opening tubular portion forming portion 25 where the opening outer wall portion 15 is formed, the opening tubular portion forming portion groove portion 25a that forms 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. 4, the tip of the opening cutting blade tip 27 b is located at a position (upward in FIG. 4) that is retracted from the parison 5 held by the excision holding part 22.
And as shown in FIG. 9, the opening part cutting blade front-end | tip part 27b is located in the cut | interruption of the opening part perimeter blade front-end | tip part 28b.

As shown in FIG. 8, the opening full circumference blade 28 is inserted into substantially the entire circumference of the cut tank opening 10, and can slide inside the tank opening 10 into and out of the cavity of the blow molding die 20. The opening cutting blade 27 is formed in a cylindrical shape having the same circumference as the inner periphery of the tank opening 10 in which the opening cutting blade 27 rotates.

An opening full circumference blade gap 28c is formed at two cylindrical locations so as to divide the full circumference blade 28 into two. As shown in FIGS. 8 and 9, the opening cutting blade tip 27 b of the opening cutting blade 27 slides in the opening all-around blade gap 28 c. In the present embodiment, the opening all-around blade gap portion 28c is provided at two locations, but may be provided only at one location, or may be provided at three or more locations.

In the case of forming a plurality of the opening all-around blade gaps 28c of the opening cutting blade 27, the same number of opening cutting blades 27 as the number of the opening all-around blade gaps 28c are provided, The peripheral blade 28 can cut the tank opening 10 with a plurality of opening cutting blades 27. Therefore, the rotation angle of the opening cutting blade 27 is reduced, the cutting time by the opening cutting blade 27 is shortened, the molding speed of the tank opening 10 is increased, the deformation of the parison to be cut is small, and the tank opening Ten deformations can also be prevented. The parison 5 that has been cut to form the tank opening 10 becomes an opening cut 18 and is removed from the tank opening 10.

Next, it is possible to prevent the cut surface of the parison 5 from being re-welded by inserting the full circumference blade 28 of the opening into the cut surface of the parison of the tank opening 10 cut by the opening cutting blade 27.
Since the opening all-around blade gap 28c in which the opening cutting blade 27 slides is formed at least at one place, the opening all-around blade 28 is cut by sliding and rotating the opening cutting blade 27. The blade 28 can be quickly inserted into the cut surface of the parison.

As shown in FIG. 10, the opening part circumferential blade tip 28 b of the opening part circumferential blade 28 has an opening part circumferential blade extension in which one side projects in the axial direction across the opening part circumferential blade gap 28 c. The protruding part 28d is formed, and the other part forms an opening full peripheral blade retreating part 28e that retreats in the axial direction. And the opening part perimeter blade inclined part 28f which inclines diagonally so that the opening part perimeter blade overhang | projection part 28d and the opening part perimeter blade retraction part 28e may be continued is formed.

For this reason, when the opening part perimeter blade 28 is inserted in the cut surface of a parison, the part of the opening part perimeter blade overhang | projection part 28d contacts the parison 5, and the opening part perimeter blade front-end | tip part 27b is a parison. 5, the friction between the parison 5 and the opening full circumference blade 28 is reduced, the rotation of the opening full circumference blade 28 is accelerated, and the formation speed of the tank opening 10 can be increased. Moreover, the load which rotates the opening part cutting blade 27 and the opening part perimeter blade 28 becomes small, the maintenance frequency of the equipment for rotating can be reduced, and the apparatus to rotate can also be reduced in size.

As shown in FIGS. 11 to 13, the thickness of the opening all-around blade slope portion 28 f is thicker on the opening all-around blade overhanging portion 28 d side, and the wall thickness increases as it goes to the opening all-around blade retracting portion 28 e. It can be made thinner gradually. In this case, the contact area between the opening part circumferential blade 28 and the parison can be reduced as a whole, and the load for rotating the opening part circumferential blade 28 can be reduced.

As shown in FIGS. 12 and 13, the shape of the opening full peripheral blade inclined surface portion 28 f of the opening full peripheral blade tip 28 b is as shown in FIG. It is a shape shown by D in FIG. 13A, and is formed so as to protrude from the other part, and the thickness X of the tip part is thicker than the other part.
The shape in the vicinity of the center of the opening all-around blade slope portion 28f is a shape indicated by E in FIGS. 12 (b) and 13 (b). Although it is slightly retracted from the portion indicated by D, it is formed so as to protrude from the portion of the opening full peripheral blade retracted portion 28e indicated by F. And the thickness Y of the front-end | tip part is a little narrower than the part shown by D.

The shape in the vicinity of the opening all-around blade receding portion 28e of the opening all-around blade inclined surface portion 28f is the shape indicated by F in FIGS. 12 (c) and 13 (c). It is slightly retracted from the part indicated by D and E. And the thickness Z of the front-end | tip part is a little thinner than the part shown by E.
For this reason, as shown in FIG. 11, the opening full circumferential blade slope 28 f of the opening full circumferential blade tip 28 b gradually extends from the opening full circumferential blade overhanging portion 28 d to the opening full circumferential blade retracting portion 28 e. The height is reduced and the thickness is reduced.

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. 3 to 7, 9, and 10, the opening cutting blade 27 has an elongated opening cutting blade tip 27 b and a cutting blade cylinder 27 a that slides the opening cutting blade tip 27 b. ing. 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 cylindrical portion forming portion 25, the opening 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. 5, the tip of the opening cutting blade tip 27 b is located at a position that has broken through the parison 5 held by the cut portion holding part 22.
As shown in FIGS. 9 and 10, the opening cutting blade tip portion 27b is positioned in the opening full-circumferential blade gap portion 28c of the opening full-circumferential blade tip portion 28b.

Next, as shown in FIG. 6, the opening cutting blade 27 is rotated so that the opening cutting blade tip 27 b is in close contact with the excision holding portion 22 of the parison 5, that is, the opening cylindrical portion forming portion 25. The opening excision part 18 which forms the tank opening part 10 is excised from the part closely_contact | adhered to. Since the opening cutting part 18 is held by the cutting part holding part 22 of the blow molding die 20, the parison 5 is hardly deformed, and the rotation of the opening cutting blade 27 causes the tank of the parison 5 at the opening cutting blade tip part 27b. The opening excision 18 of the opening 10 can be excised.

At this time, the opening full circumference blade 28 rotates together with the opening cutting blade 27. The opening circumferential blade tip 28b also rotates as the opening cutting blade tip 27b rotates, and the opening circumferential blade tip 28b is formed with an opening circumferential blade slope 28f as described later. Therefore, the tank opening 10 is not deformed because it does not contact the parison 5 or has a small contact area.

If it does so, the opening cut part 18 hold | maintained at the cut part holding | maintenance part 22 of the parison 5 will be cut | disconnected in a disk shape part by the parison cutting part 5a.
At this time, a part of the opening excision part 18 can be left to be a parison connection part. In this case, as will be described later, when the fuel tank 1 that is a blow molded product is taken out from the blow mold 20, the cut opening cut portion 18 is removed from the blow mold 20 together with the fuel tank 1. Can be taken out.

Next, as shown in FIG. 7, the full circumference blade cylinder 28a is slid to insert the opening full circumference blade tip 28b into the cut portion of the parison 5 cut by the opening cut blade tip 27b. Since the opening full peripheral blade tip 28b is formed in a full arc shape other than the narrow opening cutting blade tip 27b, the entire cutting portion of the parison 5 cut by the opening cutting blade tip 27b is formed. The opening full peripheral blade front end portion 28b can be inserted in the periphery. For this reason, it can prevent that the cut | disconnected parison 5 fuse | melts again.

And the parison 5 is cooled, and as shown in FIG. 8, the opening part cutting blade front-end | tip part 27b and the opening part perimeter blade front-end | tip part 28b are retreated toward the blow molding die 20 (upward in FIG. 8).
Thereafter, the blow molding die 20 is opened, the fuel tank 1 is taken out from the blow molding die 20, and the opening cut portion 18 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 open cut portion 18 does not fall into the fuel tank 1, and the cut open cut portion 18 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 Cutting part holding | maintenance part 27 Opening part cutting blade 27b Cutting blade front-end | tip part 28 Opening part perimeter blade 28b Opening part perimeter blade front part 28c Opening part perimeter Blade clearance 28d Opening all-around blade overhang 28e Opening all-around blade retraction 28f Opening all-around blade slope

Claims (5)

In an apparatus for forming an opening of a synthetic resin blow molded product that forms an opening of a molded product formed by blow molding in a blow mold,
The opening includes an opening cylindrical portion that extends from the outer wall of the blow-molded product and is integrally bent from the outer wall to the outside of the blow-molded product, and an opening cut from the opening cylindrical portion. Having an opening excision to form
The blow molding mold is provided with an opening cylindrical part forming part for forming the opening cylindrical part and a cut part holding part for forming the opening cut part in a part corresponding to the opening part of the blow molded product, An elongated opening cut that can slide inside and outside of the cavity inside the opening rather than the molded part of the opening cylindrical part and rotates along the periphery inside the opening to cut the opening excision Provided a blade,
A cylindrical shape that is inserted into substantially the entire circumference of the cut opening, can slide inside and outside the cavity, and has the same circumference as the inside of the opening where the opening cutting blade rotates. The opening full circumference blade is formed with an opening full circumference blade gap portion where at least one opening slides the opening cutting blade,
The front end surface of the opening all-around blade forms an opening all-around blade overhanging portion that protrudes in the axial direction across the opening all-around blade gap, and the other is in the axial direction. An opening all-around blade receding part was formed, and an opening all-around blade inclined part inclined obliquely so as to be continuous with the opening all-around blade overhanging part and the opening all-around blade retracting part was formed. An apparatus for forming an opening of a blow-molded product. 2. The blow-molded product opening forming apparatus according to claim 1, wherein a plurality of the opening cutting blades are formed, and the entire circumferential edge of the opening is divided into the same plurality as the opening cutting blade. The thickness of the inclined surface at the tip of the entire circumference of the opening was formed by increasing the thickness of the entire circumference of the opening around the blade, and gradually decreasing the thickness toward the retracted portion of the entire circumference of the opening. The blow-molded product opening forming apparatus according to claim 1. The blow molding air is blown by inserting a blow pin into a portion of the parison to be cut inside the opening to form the opening at the time of the blow molding. The blow-molded product opening forming apparatus according to Item. A receiving block is provided in a portion corresponding to the opening cut portion of the blow molding die, and the opening cutting blade rotates on the outer periphery of the receiving block, and the opening portion is cut at a front end surface of the receiving block. The blow-molded product according to any one of claims 1 to 4, wherein the opening cut-out portion cut by the blade is in close contact, and the open cut-out portion that is in close contact with the front end surface of the receiving block is removed after blow molding. Opening forming device.