JP2006088379A - Mold and molding method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of processes while avoiding the biting-in of a primary molded product due to a mold. <P>SOLUTION: An injection molding part 200 and a primary molding part 300 are formed by injection molding and a slide core 10 is subsequently replaced with a blow mold 3 while a discharge port 24 is opened by moving an intermediate core 2 to press the primary molding part 300 to the blow mold 3 to form a bellows part 301 by blow molding. By performing injection molding and blow molding continuously, the number of processes can be sharply reduced as compared with a case for performing the whole by injection molding. Since it is unnecessary to transfer a primary molded product to a blow mold, a molding cycle can be shortened and, since the blow mold 3 is only slid and moved, the biting-in of a primary molded product due to a mold can be avoided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a molding die for molding a substantially cylindrical molded body having an injection molding portion having a predetermined shape and a bulging portion bulging outward, such as an air cleaner hose, and a molding method using the molding die. About.

  Since an air cleaner hose of an automobile has a purpose of absorbing vibration and needs to be bent at the time of assembly, it is common to have a bellows portion at an intermediate position, and it is convenient to form by a blow molding method. However, since there are flanges and bosses for attachment, ribs for reinforcement and the like on the outer peripheral surface, it is necessary to form those portions by an injection molding method.

  Therefore, conventionally, an outer mold having an inner peripheral surface that molds the outer peripheral surface including the bellows portion of the product and an intermediate core having an outer peripheral surface that molds the inner peripheral surface including the bellows portion of the product are used. A method of integrally forming the bellows part by injection molding between the outer mold and the middle core is employed.

  However, in this method, when removing the molded product, the bellows part is undercut and it is difficult to perform normal mold removal. Therefore, a removal jig is inserted from one end of the molded product, and the air is removed from the removal jig. It is possible to remove the mold by expanding the bellows part by discharging. Therefore, distortion may occur in the molded product when the bellows part is expanded, and it is a problem to reduce the defect rate. In addition, not only a punching jig is required, but also the work of rotating or pulling the molded product is required at the time of mold removal, so that there is a problem that man-hours are great.

  Therefore, a method of combining injection molding and blow molding is conceivable. For example, in Japanese Patent Application Laid-Open No. 2004-090483, a product is a method in which a primary molded product having a shape in which peaks and valleys are inverted is formed by injection molding, and then a bellows having a predetermined peak and valley is formed by blow molding. Has been proposed. According to this method, the thickness of the mountain portion can be made uniform. And since the outer peripheral surface shape of a medium type respond | corresponds to the shape of a primary molded product, the peak part and trough part are reverse with the product. Therefore, the mold can be removed from the middle size without expanding the bellows portion, and the above-described problems can be solved.

However, the method described in Japanese Patent Application Laid-Open No. 2004-009083 requires a step of transferring the primary molded product to the blow mold, and in this case, the primary molded product is bitten into the blow mold and burrs may occur. is there.
JP2004-090483

  The present invention has been made in view of the above circumstances, and it is possible to reduce the number of steps by continuously performing injection molding and blow molding, and reliably avoid biting of a primary molded product by a molding die. It is a problem to be solved.

A feature of the molding die of the present invention that solves the above problems is a molding die that molds a substantially cylindrical molded body having an injection molding portion having a predetermined shape and a bulging portion that bulges outward.
An outer mold having a mold surface for molding the outer peripheral surface of the injection molded part and having a slide core at the position of the bulging part;
The cylindrical cavity formed between the first middle mold and the second middle mold and formed between the outer molds is disposed in the outer mold so as to be relatively movable in a direction close to each other and in a direction away from each other. A mold surface that molds the inner peripheral surface of the inner core, and a mold surface that molds a primary molded portion that is a precursor of the bulging portion between the slide core, and an intermediate core having an outer peripheral surface,
A blow mold having a mold surface that is exchanged with the slide core and molds the outer peripheral surface of the bulging portion,
At least one of the first medium mold and the second medium mold has a discharge port that is closed at a close position close to each other and opened at an open position spaced apart from each other,
The injection molding part and the primary molding part are formed between the outer mold with the slide core and the middle core at the closed position where the discharge port is closed, and the slide core is replaced with the blow mold and discharged at the open position where the discharge port is open. The primary forming part is swelled by discharging gas from the outlet and pressed against the blow mold to form the swelled part.

The molding method of the present invention is characterized in that a cylindrical cavity formed between the first middle mold and the second middle mold with the outer mold having a slide core at a closed position where the first middle mold and the second middle mold are close to each other is used. An injection process of injecting a molten resin to form an injection molded part and a primary molded part;
The slide core is replaced with a blow mold, and at least one of the first medium mold and the second medium mold is moved in the axial direction of the cylindrical cavity, and gas is blown out from the discharge port at the open position where the discharge port is opened to blow the primary molding part. A blow process for forming the bulging portion by pressing against a mold;
And a demolding step of opening the outer mold and the blow mold and demolding the molded body from the middle core.

  According to the molding die and the molding method of the present invention, the number of steps can be significantly reduced by performing injection molding and blow molding continuously as compared with the case where the whole is performed by injection molding. Since it is not necessary to transfer the primary molded product to the blow molding die, the molding cycle can be shortened and the biting of the primary molded product by the mold can be surely avoided.

  In the molding method using the molding die according to the present invention, first, in the injection process, the first middle mold and the second middle mold are closed to each other in a closed position formed between the outer mold having the slide core. Molten resin is injected, and an injection molded part and a primary molded part are molded. At this time, since the discharge port is closed, there is no problem that the molten resin enters the discharge port. And since it is an injection molding method, even if the shape of an injection molding part is a complicated shape, it can shape | mold easily and correctly.

  Next, in the blowing step, the slide core is replaced with a blow mold, and at least one of the first medium mold and the second medium mold is moved in the axial direction of the cylindrical cavity. As a result, the discharge port is opened, and the bulging portion is formed by blowing gas from the discharge port and pressing the primary forming portion against the blow mold. In order to mold the bulging portion, it is necessary that the primary molding portion is in a softened state to the extent that blow molding is possible.

  That is, according to the molding method of the present invention, it is not necessary to move the molded product after injection molding, and blow molding is performed in a state where the molded product is arranged in the outer mold. The blow mold can be arranged simply by sliding. Therefore, it is avoided that the molded product is caught in the molding die, and the generation of burrs due to the biting is prevented. Further, since it is not necessary to open the entire molding die, the softened state of the primary molded product can be kept optimal. The inner peripheral surface of the injection molded part is generally a cylindrical surface. Therefore, in the demolding step, there can be a configuration in which there is no undercut portion between the middle core and the molded product. Therefore, the molded body can be easily demolded by opening the outer mold and the blow mold. .

  The shape of the outer peripheral surface of the injection-molded part, that is, the mold surface shape of the inner periphery of the outer mold is not particularly limited, and can be various shapes such as a boss part and a rib. In addition, the shape of the inner peripheral surface of the injection molded part, that is, the mold surface shape of the outer periphery of the middle core is preferably a cylindrical surface shape, but in some cases, unevenness that can be removed by expanding and deforming the molded body You may have.

  The primary molded part corresponds to a precursor (parison) for forming the bulging part and is generally formed in a cylindrical shape, but the shape of the outer peripheral surface formed by the slide core is not particularly limited, and Various shapes can be obtained according to the shape of the bulging portion formed in the blowing step.

  The middle core is composed of a first middle mold and a second middle mold. The injection molding section and the primary molding section are molded between the first middle mold and the second middle mold in a closed position close to each other and the outer mold having the slide core. Is done. The discharge port may be formed in one of the first medium mold and the second medium mold, or may be formed between the two. For example, a discharge port is formed on the outer peripheral surface of one of the first medium mold and the second medium mold, and one of the first medium mold and the second medium mold enters the inside of the other so that the discharge port opening is covered, and the discharge port opens at the open position. Constitute. Alternatively, the discharge port is formed by forming a discharge port on the front end surface of at least one of the first medium mold and the second medium mold, and the front end surfaces of the both are in contact with each other in the closed position. It can also be configured such that the discharge port opens by being separated.

  The blow mold has a mold surface for molding the outer peripheral surface of the bulging portion, and is formed to be exchangeable with the slide core. The shape of the bulging portion is not limited as long as it can be formed by blow molding from the primary molding portion, such as a bellows shape, a box shape, or a container shape.

  Hereinafter, the present invention will be described specifically by way of examples. FIG. 1 shows a molded body 100 manufactured in this example. This molded body is an air cleaner hose, and an injection molding part 200 such as a rib 201 and a boss 202 is formed at both ends, and a bellows part 301 (bulging part) is formed at an intermediate part. The inner peripheral surface of the injection molded part 200 is a smooth cylindrical surface.

  2-6 shows the molding die of a present Example and the shaping | molding method using the same. This molding die is composed of an outer mold 1 opened in the vertical direction on the paper surface and having a slide core 10, a middle core 2 disposed inside the outer mold 1, and a blow mold 3 replaced with the slide core 10. Has been.

  The outer mold 1 has a mold surface 11 that forms the injection molding part 200, and the mold surface of the slide core 10 is formed in a cylindrical surface shape. The blow mold 3 shown in FIGS. 4 and 5 has a bellows-shaped mold surface 30 corresponding to the outer peripheral surface of the bellows portion 301 and is formed to be replaceable with the slide core 10.

  The middle core 2 includes a substantially cylindrical first middle mold 20 in a fixed state and a second cylindrical middle mold 21 that is arranged coaxially with the first middle mold 20 and is movable in the axial direction. The first middle mold 20 has a truncated cone part 22 having a smaller diameter at the distal end, and an air flow path 23 that extends in the axial direction at the center and branches in the middle and opens on the outer peripheral surface of the truncated cone part 22 is formed. Yes. One end of the air flow path 23 is connected to a compressor (not shown), and the opening of the air flow path 23 on the outer peripheral surface of the truncated cone part 22 constitutes the discharge port 24. In addition, a concave portion 25 is formed at the distal end portion of the second middle mold 21 so as to have a larger diameter toward the distal end and engage with the truncated cone portion 22.

  In the molding method of the present embodiment, first, the middle core 2 integrated by the engagement of the truncated cone portion 22 with the recess 25 is disposed in the outer mold 1 as shown in FIG. The slide core 10 is moved forward by clamping the mold. A substantially cylindrical cylindrical cavity 12 is formed between the outer mold 1 and the middle core 2. In this state, a polyester thermoplastic elastomer in a molten state is injected from a gate (not shown), and injection molding is performed.

  As a result, as shown in FIG. 3, an injection molded part 200 having ribs 201, bosses 202 and the like on the outer peripheral surface and a cylindrical primary molded part 300 are formed.

  Next, as shown in FIG. 4, the slide core 10 is replaced with the blow mold 3 while maintaining the clamped state of the outer mold 1. At the same time, the second middle mold 21 is slid in the axial direction by a predetermined distance in the direction away from the first middle mold 20 to expose the mold surface 30 of the blow mold 3 and the discharge port 24. Then, while the tubular primary molded part 300 is deformable, pressurized air is supplied to the air flow path 23 and discharged from the discharge port 24. As a result, the primary molding portion 300 is bulged and deformed and pressed against the mold surface 30, and the bellows portion 301 is molded as shown in FIG.

  After the molded body 100 is solidified, the blow mold 3 and the outer mold 1 are opened, and the second middle mold 21 is removed from the molded body 100. Further, the push-up pin 26 protrudes from the first middle mold 20 and presses the molded body 100 in the axial direction, whereby the molded body 100 is removed from the first middle mold 20.

  That is, according to the present embodiment, since blow molding is performed with the injection molded product held in the outer mold 1, it is not necessary to move the molded product from the molding die after injection molding. Therefore, the molding cycle can be shortened. Further, when the slide core 10 is replaced with the blow mold 3, the inner diameter of the blow mold 3 does not become smaller than the outer diameter of the primary molding part 300 and can be replaced only by sliding the blow mold 3. . Therefore, it is possible to reliably avoid biting of the primary molded product by the molding die.

  In this embodiment, the discharge port 24 is formed on the outer peripheral surface of the first middle mold 20, but the discharge port 24 may be formed on the front end surface of the first middle mold 20 as shown in FIG. As shown, the discharge port 24 may be formed on the tip surface of the second middle mold 21.

  The molding die and molding method of the present invention can be used not only for the production of various molded products having an injection molding part and a blow molding part, as well as an air cleaner hose having a bellows part.

It is a perspective view of the molded object manufactured by one Example of this invention. In one Example of this invention, it is sectional drawing which shows the shaping die of the mold clamping state before an injection process. In one Example of this invention, it is sectional drawing which shows the shaping die immediately after an injection process. In one Example of this invention, it is sectional drawing which shows the shaping die before a blow process. In one Example of this invention, it is sectional drawing which shows the shaping die immediately after a blow process. In one Example of this invention, it is sectional drawing which shows the shaping die at the time of a demolding process. It is sectional drawing which shows the other aspect of the Example of this invention, and shows the shaping die immediately after a blow process. It is sectional drawing which shows the other aspect of the Example of this invention, and shows the shaping die immediately after a blow process.

Explanation of symbols

1: Outer mold 2: Medium core 3: Blow mold
10: Slide core 20: First medium type 21: Second medium type

Claims (2)

A molding die for molding a substantially cylindrical molded body having an injection molding portion of a predetermined shape and a bulging portion that bulges outward,
An outer mold having a mold surface for molding the outer peripheral surface of the injection molded part and having a slide core at the position of the bulging part;
A cylindrical cavity formed between the first intermediate mold and the second intermediate mold and disposed in the outer mold so as to be relatively movable in a direction close to each other in the axial direction and in a direction away from each other. A mold surface that molds the inner peripheral surface of the injection-molded portion, and a mold surface that molds a primary molded portion that is a precursor of the bulging portion between the slide core, and an intermediate core having an outer peripheral surface;
A blow mold having a mold surface which is exchanged with the slide core and molds the outer peripheral surface of the bulging portion,
At least one of the first medium mold and the second medium mold has a discharge port that is closed at a close position close to each other and opened at an open position spaced apart from each other,
The injection molding part and the primary molding part are molded between the outer mold having the slide core and the middle core at the closed position where the discharge port is closed, and the slide core is replaced with the blow mold. A molding characterized in that the bulging portion is formed by bulging the primary molding portion by discharging gas from the discharge port at the open position where the discharge port is opened and pressing the blow molding. Mold. A molten resin is used in a cylindrical cavity formed between the outer mold having the slide core at the closed position where the first middle mold and the second middle mold are close to each other using the molding die according to claim 1. An injection step of forming the injection molded part and the primary molded part by injecting
The slide core is replaced with the blow mold, and at least one of the first medium mold and the second medium mold is moved in the axial direction of the cylindrical cavity, and gas is discharged from the discharge opening at the open position where the discharge opening is opened. Blowing step to form the bulging portion by pressing the primary molding portion against the blow mold; and
And a demolding step of opening the outer mold and the blow mold and demolding the molded body from the middle core.

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