JP2006315266A - Biaxially stretching blow molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially stretching blow molding method which uses an injection molding machine which does not use large-scaled equipment and which gives containers by the biaxially stretching blow molding which have good quality. <P>SOLUTION: On the injection molding machine there are conducted successively a first step wherein the preform 10 is injection molded, a second step wherein the molded preform is adjusted to a stretching temperature, a third step wherein the preform that has been adjusted to the stretching temperature is stretched to the vertical direction in a split mold for the blow molding, a fourth step wherein the preform that has been stretched to the vertical direction is subjected to blow molding, and a fifth step wherein the molded container by the biaxially stretching blow molding is taken out, all the steps being performed within the same station. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention uses a crystalline thermoplastic resin such as polyethylene terephthalate and polypropylene to form a preform (bottom parison) and biaxially stretch on one injection molding machine without moving to another station. The present invention relates to a biaxial stretch blow molding method for forming a blow molded container.

  Conventionally, methods for forming a biaxially stretched blow molded container using a crystalline thermoplastic resin include a one-step hot parison in-line molding method and a two-step cold parison method. In the parison / inline molding method, a preform is first molded at a preform injection molding station on one injection molding machine, and then the preform immediately after molding is held by a neck and neck mold split mold. Move to the preform heating station and heat the preform to adjust to the temperature suitable for stretching, and then transfer the preform adjusted to this temperature to the stretching and blow molding station by holding the neck and neck mold in the mold. The reform is stretched in the longitudinal direction and then blow molded to form a biaxial stretch blow molded container. Next, the biaxial stretch blow molded container is held by a neck and neck mold split mold. Transferred to molded article removal station, to open the neck mold split mold were those taking out biaxial stretch blow molding containers.

  However, in the hot parison in-line molding method for forming the conventional biaxial stretch blow molded container described above, a preform injection molding station, a preform heating station, a stretching and blow molding station, and a molded product take-out station are formed on an injection molding machine. Because of this, the molding equipment becomes large, and it is necessary to reinsert the core pin in the mouth and neck, the mouth inner diameter of the mouth and neck changes, the inner peripheral surface is easily damaged, and the When moving the renovation to another station, the temperature dropped and it was easily affected by the atmosphere.

  The present invention solves the above-mentioned problems of the conventional biaxial stretch blow molding method, uses an injection molding machine, does not require large molding equipment, and has a good quality of the molded biaxial stretch blow molded container. A biaxial stretch blow molding method is provided.

  That is, the first invention of the present invention includes a first step of sequentially injection-molding a preform on a injection molding machine, a second step of adjusting the formed preform to a stretching temperature, and a blow molding split. A third step of stretching the preform adjusted to the stretching temperature in the mold in the longitudinal direction, a fourth step of blow-molding the preform stretched in the longitudinal direction, and a fifth step of taking out the molded biaxially stretched blow-molded container A biaxial stretch blow molding method characterized in that the steps are performed in the same station.

Next, according to a second aspect of the present invention, a preform injection mold includes a female mold and a male mold, and the female mold has a gate for injection molding. It consists of a mold and a mouth-and-neck mold split mold, and the male mold has a center core with a cooling water channel, an outer core that forms a cooling water channel communicating with the cooling water channel, and an air channel on the inner peripheral surface side. A cylindrical sleeve, an outer core mounting plate that has a cooling water discharge path that projects from the outer core and communicates with the cooling water path, and an air supply path that communicates with the air path, and a center at the lower end of the outer core mounting plate An annular blocking plate that seals around the core, a center core mounting plate that protrudes from the center core and has a cooling water supply passage that communicates with the cooling water passage, and an inner block that can move the outer core mounting plate can slide. Built-in outer block and predetermined position The biaxially stretched blow mold is composed of a blow mold female mold and a stretch / air blow mold, and the blow mold female mold is a left side split mold and a body section. It consists of a right split mold and a bottom mold, and the stretching and air blowing mold is a male mold of the preform injection mold, and in the first step and the second step, the male mold Between the outer core mounting plate and the center core mounting plate of the side mold, a predetermined interval is maintained by a contact inner block, and in the first step, the female mold is clamped to the male mold. The molten molding resin is injected from the gate and cooled to form a preform, and in the second step, the female side mold is opened and the mouth-and-neck molding split mold is moved to the predetermined position in the axial direction. Outer core mounting play while renovating sliding the outer surface of the cylindrical sleeve Open the mouth and neck molding split mold away from the mold, and in the third step, clamp the blow molding female mold and simultaneously close the mouth and neck molding split mold, and set the gap between the outer core mounting plate and the center core mounting plate. The contact inner block is moved into the outer block and closed, and the preform is stretched in the axial direction by blowing the primary air at the tip of the center core and a predetermined pressure. In the fourth step, the preform is blown by the secondary air blowing at a predetermined pressure. In the fifth step, the blow-molding female mold and the mouth-and-neck part split mold are opened, and the formed biaxial stretch blow-molded container is taken out. 2 is a biaxial stretch blow molding method.

  A third invention of the present invention is the biaxial stretch blow molding method according to the first or second invention, wherein the molding material is a crystalline thermoplastic resin.

  In the biaxial stretch blow molding method of the present invention, the preform is injection molded in the same station of the injection molding machine, the preform stretching temperature is adjusted, and the preform in the blow molding mold is stretched in the longitudinal direction. In this case, blow molding is performed, and a plurality of stations are not required unlike a conventional biaxial stretch blow molding machine, so that the molding apparatus is not large.

  In addition, the biaxial stretch blow molding method of the present invention does not move the preform to another station by reinserting the core pin into the mouth neck of the preform unlike the conventional biaxial stretch blow molding. The neck inner diameter changes, the inner peripheral surface is scratched, the heat of the preform is taken away, and the wall thickness distribution is stable due to the influence of the atmosphere. The quality of the formed biaxially stretched blow molded container is good.

  Next, an embodiment of the biaxial stretch blow molding method of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the structure of the main part of a preform injection mold, FIG. 2 shows a state in which the preform immediately after injection molding is floated and the stretching temperature is adjusted, and FIG. 3 shows a blow mold split mold. FIG. 4 shows a state in which the preform is stretched in the longitudinal direction, FIG. 4 shows a state in which the container is blow-molded, and FIG. 5 shows the formed biaxially stretched blow-molded container from the blow molding die. Indicates the state of removal. FIG. 6 shows the operating state of the mouth-and-neck molding split mold.

  The biaxial stretch blow molding method of the present embodiment uses, for example, a crystalline thermoplastic resin such as polyethylene terephthalate, polypropylene, polyethylene, polyethylene naphthalate, and nylon, or a blend material of crystalline thermoplastic resin, at the same station of an injection molding machine. Among them, the preform is formed and the biaxial stretch blow-molded container is formed without moving the preform to another station.

The molding process of the biaxial stretch blow molding method of this embodiment consists of five processes. First, as shown in FIG. 1, the first process is a process of injection molding a preform (10) with an injection molding die. The next second step is a step of adjusting the molded preform (10) to the stretching temperature as shown in FIG. 2, and the next third step is for blow molding as shown in FIG. In the split mold (120), the preform (10) adjusted to the stretching temperature is stretched in the longitudinal direction (indicated by an arrow), and the next fourth step is a blow molding split as shown in FIG. This is a step of forming a preform stretched in the longitudinal direction in the mold (120) into a biaxial stretch blow-molded container (20) by blow molding, and the fifth step is for blow molding as shown in FIG. A biaxial stretch blow molded container formed by opening the split mold A step of taking out the molded article take-out robot.

  Next, the preform injection mold used in the biaxial stretch blow molding method of the present embodiment is composed of a female mold and a male mold, as shown in FIG. The mold is composed of an injection molding female mold (110) having a gate (111) at a position corresponding to the center position of the outer peripheral surface of the bottom of the preform (10), and a neck and neck molding split mold (150). The side mold has a center core (130) having a tip end portion (131) at the upper end and a fixing flange portion (133) at the lower end and a cooling water channel (132) at the center, and communicates with the cooling water channel (132). The cooling water channel (141) is formed on the outer peripheral surface of the center core, the outer core (140) having a fixing flange portion (142) at the lower end, and the fixing flange portion (172) at the lower end, and on the inner peripheral surface side. A cylindrical slot that forms an air passage (171) with the outer peripheral surface of the core And an air supply path (162) having a cooling water discharge path (161) projecting from the outer core and communicating with the cooling water path (141) of the outer core and communicating with the air path (171) of the cylindrical sleeve. ) Having an outer core mounting plate (160), an annular sealing plate (180) sealing around the center core (130) at the lower end of the outer core mounting plate, and a center core cooling water channel (132) protruding from the center core. A center core mounting plate (190) having a cooling water supply path (191) communicating with the outer core mounting plate, and a contact outer block (202) slidably including a contact inner block (201) for moving the outer core mounting plate; It consists of a plurality of springs provided at predetermined positions. Each member is fastened with bolts as necessary, and a 0-ring is embedded in a necessary portion in order to prevent leakage of cooling water. The biaxially stretched blow mold is composed of a blow mold female mold and a stretch / air blow mold. As shown in FIG. 4, the blow mold female mold (120) is a left side split mold. (121), a body right split mold (122), and a bottom mold (123), and the stretching and air blowing mold is a female mold on a preform injection mold in which a preform is injection molded. Is used as it is.

Next, operation in each step of the preform injection mold and the biaxial stretch blow mold will be described. In the first step, as shown in FIG. 1, the female mold is clamped to the male mold, and the cavity (male mold and the male mold) is formed from the gate (111) of the preform injection mold female mold (110). The melt molding resin is injected into the space between the female molds) and cooled to mold the preform (10). In the second step, as shown in FIG. 2, the female side mold is opened and the mouth-and-neck portion split mold is moved in the axial direction to a predetermined position, and the preform is slid onto the outer peripheral surface of the cylindrical sleeve. After being separated from the outer core mounting plate by a predetermined position while being in contact, the mouth-and-neck molded left split mold (151) and the mouth-and-neck molded right split mold (152) are opened, and the preform is floated. The temperature is made uniform so that the preform has a suitable stretching temperature. As shown in FIG. 6, the operation of the left and right mouth mold (151) and the right neck mold (152) is performed by three internal springs (213, 214, 215). Is. Further, in the first step and the second step, a predetermined distance is maintained between the outer core mounting plate (160) and the center core mounting plate (190) of the male mold by the contact inner block (201). To do. In the third step, as shown in FIG. 3, the blow mold female mold (120) is clamped, and at the same time, the neck and neck mold split mold (150) is closed, and the outer core mounting plate (160) and the center core are mounted. The inner block (201) is moved into the outer block (202) to close the gap between the plates (190), and as a result, the tip (131) of the projecting center core (130) and the primary air blow ( (For example, 0.01-15.20 seconds at 13-15 bar)
Thus, the preform is stretched in the axial direction. In the fourth step, as shown in FIG. 4, a preform stretched in the axial direction is blow-molded by secondary air blowing at a predetermined pressure (for example, 15 to 45 bar) to form a biaxial stretch blow-molded container (20). It is to be molded. Then, in the fifth step, as shown in FIG. 5, the left side split mold (121) and the right side split mold (122) of the blow mold female mold and the left side split of the mouth and neck mold split mold The mold (151) and the right and left split mold (152) of the mouth and neck are opened in the left-right direction, and the formed biaxially stretched blow molded container (20) is picked up by, for example, a molded product take-out robot (300) and taken out. is there.

It is explanatory drawing which shows the structure of the principal part of the metal mold | die for preform injection molding of the 1st process in the biaxial stretch blow molding method of one Embodiment of this invention. It is explanatory drawing which shows the state which floats the preform immediately after injection molding in a 2nd process, and adjusts the temperature for biaxial stretch blow molding. It is explanatory drawing which shows the state which extends a preform to a vertical direction generally in the split mold for blow molding in a 3rd process. It is explanatory drawing which shows the state which blow-molds a container in the split mold for blow molding in a 4th process. It is explanatory drawing which shows the state which takes out the biaxial stretch blow molding container shape | molded in the 5th process from the metal mold | die for blow molding. It is explanatory drawing which shows the operation state of the opening-and-neck part shaping | molding split mold in a 2nd process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Preform 11 ... Mouth and neck part 20 ... Biaxial stretch blow molding container 110 ... Injection mold female mold 111 ... Gate 120 ... Blow molding split mold 121 ... Trunk part left side split mold 122 ... ... Right-side split mold 123 …… Bottom mold 130 …… Center core 131 …… Tip 132,141 …… Cooling channel 133,142,172 …… Fastening flange 140 …… Outer core 150 …… Port neck Molding mold 151... Neck and neck molding left split mold 152. Mouth and neck molding right split mold 160... Outer core mounting plate 161... Cooling water discharge path 162 .. air suction path 170. ...... Air path 180 ...... Rolling sealing plate 190 ...... Center core mounting plate 191 ...... Cooling water suction path 201 ...... Contact inner block 202 ...... Contact outer block 211, 212, 213, 21 , 215 ...... spring 220 ...... interval 300 ...... product removal robot

Claims (3)

  On the injection molding machine, the first step for sequentially injection-molding the preform, the second step for adjusting the molded preform to the stretching temperature, and the preform adjusted to the stretching temperature in the blow molding split mold vertically The third step of stretching in the direction, the fourth step of blow molding the preform stretched in the longitudinal direction, and the fifth step of taking out the molded biaxially stretched blow molded container are performed in the same station, Biaxial stretch blow molding method.   The preform injection mold consists of a female mold and a male mold, and the female mold consists of an injection mold female with a gate and a neck and neck mold split mold, The male mold has a center core having a cooling water channel, an outer core that forms a cooling water channel communicating with the cooling water channel, a cylindrical sleeve that forms an air channel on the inner peripheral surface side, and an outer core. An outer core mounting plate having a cooling water discharge path communicating with the cooling water path and having an air supply path communicating with the air path; an annular sealing plate for sealing around the center core at the lower end of the outer core mounting plate; And a center core mounting plate having a cooling water supply passage communicating with the cooling water passage, a contact outer block that slidably houses a contact inner block that moves the outer core mounting plate, and a plurality of blocks provided at predetermined positions. From the springs The biaxially stretched blow mold consists of a blow mold female mold and a stretch / air blow mold, and the blow mold female mold consists of a barrel left split mold, barrel right split mold, and bottom mold. The extending and air blowing mold is the male mold of the preform injection mold, and the outer core mounting plate of the male mold is used in the first step and the second step. And a center core mounting plate, a predetermined distance is maintained by a contact inner block, and in the first step, the female mold is clamped to the male mold and the molten molding resin is injected from the gate. Then, the preform is formed by cooling, and in the second step, the female side mold is opened and the neck and neck forming mold is moved to the predetermined position in the axial direction so that the preform is outer peripheral surface of the cylindrical sleeve. While being in sliding contact with the outer core mounting plate, In the third step, the female mold for blow molding is clamped and the neck and neck molding split mold is closed at the same time, and the inner block is moved into the outer block by hitting the space between the outer core mounting plate and the center core mounting plate. The preform is stretched in the axial direction by blowing the primary air with a predetermined pressure at the front end of the center core, and in the fourth step, the preform is biaxially stretched and blow-molded by blowing the secondary air at a predetermined pressure. 2. The biaxial stretch blow molding method according to claim 1, wherein in the step, the blow mold female mold and the mouth-and-neck mold split mold are opened, and the formed biaxial stretch blow molded container is taken out.   The biaxial stretch blow molding method according to claim 1 or 2, wherein the molding material is a crystalline thermoplastic resin.

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