JP6795348B2 - Molding method and molding equipment for molten material - Google Patents

Description

The present invention relates to a method for molding a molten material by molding a molten material by a molding die including a split mold in which an air vent hole is formed, and particularly in an air vent hole in a state where the molten material is present in a cavity of the molding die. The present invention relates to a molding method and a molding apparatus for a molten material, which also cleans an air vent hole by supplying a gas.

Conventionally, there are an injection molding method, a compression molding method, and the like as a molding method for molding a molten material that has been heated and melted by using a molding die. For example, in the injection molding method, a molten material is injected and filled into a cavity (cavity) formed by a pair of split dies, and the molten material in the cavity is cooled and solidified to form the molten material into the shape of the cavity. That is.
The split die is provided with an air vent hole in order to discharge the air (air) existing in the cavity to the outside of the cavity when the molten material is filled in the cavity.
Not limited to such an injection molding method, in any method of filling a predetermined cavity with a molten material and molding it into a shape matching the cavity shape, the molten material or the molten material component vaporized on the surface of the air vent hole. If left unattended, there is a problem that the air vent hole is blocked and air bleeding failure occurs. In order to eliminate such stains on the air vent holes, the work of cleaning the air vent holes with a cloth or the like has been performed after performing molding a certain number of times or for a certain period of time.

However, in the above-mentioned cleaning work, the molding cycle must be interrupted each time the cleaning is performed, which has the disadvantage that the productivity is lowered. In order to solve such a problem, Patent Document 1 and the like have proposed a method of performing cleaning without interrupting the molding cycle.
The means proposed in Patent Document 1 is a gas vent provided in a molding die by supplying a cleaning gas from the gas inflow path when the pair of molding dies forming the cavity is opened. It is to clean the. As a result, the gas vent and its peripheral portion can be effectively cleaned without interrupting the molding cycle.

The molding mold can be cleaned by the means proposed in Patent Document 1 without lowering the productivity. Although the above means can remove foreign substances such as resin dust and dust, the resin It is not enough to remove very fine foreign substances composed of low molecular weight components (oligomers) contained in the article, and if the oligomer accumulates in the vent groove, poor degassing, air bubbles in the molded product, short molding, etc. Causes molding defects. Therefore, after repeating molding a certain number of times or for a certain period of time, it is necessary to stop molding and clean the surface of the molding mold by manual wiping or the like.

Patent Document 2 has been proposed as a means for solving the above problems. That is, after molding is performed once and the molded product is taken out from the molding mold, the mold is formed or the molding mold is not completely formed but the air vent hole is formed prior to the next molding. In the formed state, cleaning gas is flowed from the gas inflow path to a very narrow air vent hole. As a result, the vent groove forming the air vent hole and the peripheral portion thereof can be effectively cleaned, the accumulation of oligomers contained in the molding resin can be effectively prevented, and the molding operation is not stopped for a long period of time. It is possible to carry out continuously over.

Japanese Unexamined Patent Publication No. 9-19948 International Publication No. 2015/093256

However, in the plastic molding method described in Patent Document 2, after the molded product is taken out from the molding mold, the cavity gap is not closed with resin or a part of the molding mold is largely open to the atmosphere. Since the cleaning gas is supplied in the above, there is a problem that the consumption of the cleaning gas increases. In addition, the pressure loss of the cleaning gas increases, and it is difficult to maintain the cleaning pressure at the air vent hole, so that the cleaning efficiency may decrease.
In addition, since the cleaning process is performed after the molded product is taken out from the molding die and prior to the next molding, it is possible to carry out the process continuously, but it is necessary to secure a long time for the cleaning process, which is necessary for production. There was a risk that the speed would slow down.

The present invention solves these problems, suppresses the consumption of cleaning gas, and effectively cleans the vent groove forming the air vent hole and its peripheral portion with a stable cleaning pressure. It is an object of the present invention to provide a molding method and a molding apparatus for a molten material capable of effectively preventing the accumulation of vaporized components and low molecular weight components of the molding material.

In the method for molding a molten material of the present invention, a gas inflow path and the said A molding method for a molten material, which is formed by filling, cooling and solidifying a material that has been heated and melted in the cavity by using a molding die including a split mold in which an air vent hole leading to the cavity is formed. With the mold closed and the material present in the cavity, the cleaning gas is supplied from the gas inflow path to the air vent hole and discharged from a place different from the gas inflow path to form the cleaning gas. The above problem is solved by the injection pressure being 0.3 MPa or more and 5.5 MPa or less and the injection time of the cleaning gas being 0.5 seconds or more and 1.5 seconds or less .
Further, the molten material molding apparatus of the present invention is an apparatus for producing a molded product by the molten material molding method, has a gas supply mechanism for supplying the cleaning gas to the air vent hole, and supplies the gas. The mechanism is provided with a control unit that controls the supply timing of the cleaning gas so as to supply the gas to the air vent hole between the start of the flow of the molten material in the cavity and the removal of the molded product. By doing so, the above-mentioned problem is solved.

According to the method for molding a molten material of the present invention, since the cleaning gas is supplied in the state where the material is present in the cavity of the molded mold, many parts in the cavity are closed with the material and the cavity is formed. By reducing the amount of cleaning gas that flows into the inside or the amount of cleaning gas that leaks from the gaps of cavities other than the air vent holes, the amount of cleaning gas consumed can be reduced, and the amount of cleaning gas that should be cleaned can be reduced. It is possible to maintain the pressure and flow velocity of the cleaning efficiency.
Further, the cleaning gas injection pressure is 0.3 MPa or more and 5.5 MPa or less, and the cleaning gas injection time is 0.5 seconds or more and 1.5 seconds or less, so that effective cleaning can be performed in a short time. Cleaning of the area to be done can be carried out.

According to the molten material molding apparatus of the present invention, since a gas supply mechanism having a control unit for controlling the supply timing of the cleaning gas supplied from the gas inflow path to the air vent hole is provided, the gas supply mechanism is supplied by the control unit. By adjusting the timing, the timing to supply the cleaning gas while the material is present in the cavity can be easily set and changed, the consumption of the cleaning gas can be reduced, and the cleaning gas at the place to be cleaned can be reduced. It is possible to maintain the pressure and flow velocity of the gas and improve the cleaning efficiency.

Sectional drawing of preform M for a container. The whole view (cross-sectional view of the front view and the back view) of the preform molding apparatus 100 for a container. Cross-sectional view (plan view) and arrow view AA'and BB'cross-sectional view of the neck female mold 114. Cross-sectional view (front view) and side view of the core mold 111. FIG. 5 is a cross-sectional view (plan view) showing the operation of the female neck mold 114. FIG. 5 is a cross-sectional view (plan view) showing the operation of the body female mold 119. A cross-sectional view (plan view) showing a state in which the molding die 110 is closed. A CC'cross-sectional view and a DD' cross-sectional view showing a state when the resin P is filled in the molding die 110. A CC'cross-sectional view and a DD' cross-sectional view showing a state when the cleaning gas G is supplied. FIG. 5 is a cross-sectional view (plan view) showing a procedure for taking out the container preform M from the molding die 110.

Hereinafter, the container preform molding apparatus 100 according to the embodiment using the method for molding a molten material of the present invention will be described with reference to the drawings.

The container preform M is an intermediate molded body for molding a bottle-shaped container by a known biaxial stretch blow molding, and is molded from a thermoplastic resin such as a polyester resin or a polyolefin resin as a molten material. As shown in FIG. 1, it is formed of a test tube-shaped body portion Ma and a neck portion Mb having a thread and a support ring formed on the outer surface.
As shown in FIGS. 2 to 4, the container preform molding apparatus 100 includes a molding die 110 and a gas supply mechanism 130 that supplies a cleaning gas G to the molding die 110 (gas inflow path 118). There is.

The molding dies 110 are a male core mold 111, a female mold, and a pair of female split dies 114a and 114b which are relatively movable to abut and separate from each other. It has a body cavity mold 119.
The core mold 111 is provided with a core base 112 and an inner peripheral surface forming portion 113 that mainly resembles the shape of the inner peripheral surface of the container preform M and partially resembles the shape of the top surface portion. Further, the core mold 111 is provided with a gas inflow path 118 for supplying cleaning gas from the gas supply mechanism 130 to the air vent holes 122 formed by the neck split molds 114a and 114b.

The neck split dies 114a and 114b are provided with split surfaces 115a and 115b that come into contact with each other when they are butted against each other, and neck forming portions 116a and 116b that imitate the outer peripheral surface shape of the neck Mb.
Further, a shallow and wide groove-shaped vent groove 117 is formed at a position adjacent to the neck forming portion 116a of the dividing surface 115a. Further, a discharge auxiliary groove 117a is formed on the outer side of the mold of the vent groove 117, and a gas discharge groove 117c extending from the discharge auxiliary groove 117a to the outer periphery of the neck split mold 114a is formed. When the dividing surface 115a and the dividing surface 115b are butted against each other, an air vent hole 122 is formed by the vent groove 117 and the dividing surface 115b. Similarly, by abutting the divided surfaces, the discharge auxiliary flow path 117b is formed by the discharge auxiliary groove 117a and the division surface 115b, and the gas discharge path 117d is formed by the gas discharge groove 117c and the division surface 115b.

The body cavity mold 119 includes a body forming portion 120 that imitates most of the outer peripheral surface shape of the preform body portion Ma for containers, and a gate that penetrates the body cavity mold 119 from the bottom surface of the body forming portion 120. 121 and are formed.
By abutting these molds at predetermined positions and closing the molds, a cavity 123, which is a cavity in the shape of the container preform M, is formed in the mold 110.

At the time of molding the container preform M, a molten resin P obtained by heating and melting a thermoplastic resin is injected and filled into the cavity 123 from the gate 121 by using an injection molding machine (not shown).
The gas supply mechanism 130 is configured to be able to supply the cleaning gas G to the gas inflow path 118. Further, the gas supply mechanism 130 is provided with a control unit (not shown) capable of controlling the supply timing of the cleaning gas G.
Compressed air is usually used as the cleaning gas G, but an inert gas such as nitrogen gas, carbon dioxide gas, or other gas may be used as long as it does not adversely affect the environment or the molding mold. it can. The cleaning gas G is preferably a gas that has been sterilized. The preferable pressure of the cleaning gas is 0.3 to 5.5 MPa, and the more preferable pressure is 2.0 to 4.5 MPa. By setting such a pressure, the air vent hole 122 (air vent groove 117) and its surroundings can be effectively cleaned in a short time.

Next, the procedure for molding the container preform M and cleaning the mold by the container preform molding apparatus 100 in the present embodiment will be described.
First, as shown in FIG. 5, by abutting the neck split molds 114a and 114b so as to surround the inner peripheral surface forming portion 113 of the core mold 111, as shown in FIG. 6, the air vent hole 122 and the pump are A space is formed in the shape of the neck Mb of the remodeling. Next, the neck split mold 114 is abutted against the body cavity mold 119 so that the inner peripheral surface forming portion 113 of the core mold 111 penetrating the neck split mold 114 is included in the body portion forming portion 120. As a result, as shown in FIG. 7, a space that imitates the shape of the body portion Ma is formed. As a result, the cavity 123 of the preform M is formed in the molding die 110.

While maintaining this state, as shown in FIG. 8A, the molten resin P is injected and filled into the cavity 123 from the gate 121.
At this time, as shown in FIG. 8B, the residual air K existing in the cavity 123 when the molten resin P is filled is removed from the gas discharge path 117d through the air vent hole 122 and the discharge auxiliary flow path 117b to the molding die 110. Since it is quickly discharged to the outside of the container, air bubbles are not mixed in the molded container preform M, and defects such as short molding do not occur. Further, a trace amount of oligomer contained in the molten resin P as an unavoidable impurity also reaches and adheres to the air vent hole 122 along with the flow of the residual air K discharged. The air vent hole 122 (air vent groove 117) has a depth of 0.01 to 0.05 mm and a width of about 1 to 10 mm, which is sufficiently narrow, and the gap between the butt surfaces of each mold is also sufficiently narrow. There is no gap. Therefore, a large amount of the molten resin P does not enter the air vent hole 122 or the abutting surface of each mold.

The molten resin P that has completed injection filling and filled the inside of the cavity 123 is cooled by each mold appropriately cooled by a cooling circuit (not shown) or the like, and the temperature gradually decreases and solidifies. Since the volume of the molten resin P shrinks as the temperature decreases, the molten resin P is additionally replenished (holding pressure) from the gate 121 into the cavity 123 as needed. The solidified resin P is held in the mold 110 for a predetermined time for further cooling. The control unit of the gas supply mechanism 130 supplies the cleaning gas G to the gas inflow path 118 as shown in FIG. 9A after the injection filling of the molten resin P is completed.
The cleaning gas G is discharged from the gas inflow path 118 through the air vent hole 122 to the outside of the mold 110 through the discharge auxiliary flow path 117b and the gas discharge path 117d. At this time, the oligomer adhering to the air vent hole 122 is removed by the cleaning gas G. As a result, the accumulation of oligomers in and around the air vent hole 122 can be effectively prevented.

Further, since the cavity 123 is filled with the molten resin P or the solidified resin P, a large amount of the cleaning gas G does not flow into the cavity 123, and the cleaning gas that has flowed into the cavity 123. A large amount of cleaning gas G does not leak from the gap between the inlet of the gate 121 and the tip of the injection nozzle or the tip of the hot runner of the injection molding machine (not shown).
Further, the cleaning gas G flowing into the cavity 123 does not leak in a large amount from the gap between the neck split mold 114a (or 114b) and the body cavity mold 119. Therefore, the cleaning gas G does not flow out from the useless gap and flows into the air vent hole 122 in a concentrated manner, so that the cleaning efficiency can be improved while suppressing the supply amount of the cleaning gas G.
Further, since the cleaning gas G is supplied after the injection filling of the molten resin P is completed, it becomes difficult for the cleaning gas G to enter between the cavity 123 and the molten resin P, and traces such as air marks are left on the molded preform M. It will not remain. Further, if the cleaning gas G is supplied at the stage where the molten resin P is cooled and solidified after the holding pressure, it is more effective in suppressing the air traces of the molded preform M.

The control unit of the gas supply mechanism 130 is in the holding pressure, or after the molten resin P is sufficiently cooled, by the time the preform M is taken out at the latest (connection and division between the gas inflow path 118 and the air vent hole 122). Before the abutting of the surfaces 115a and 115b is released, by the time the state shown in the upper part of FIG. 10 is released, more preferably by the time the state shown in FIG. 9 before opening the molding die 110 is released). The supply of the cleaning gas G is stopped, and a large amount of the cleaning gas G is suppressed from flowing out. Then, as shown in FIG. 10, the molding die 110 is opened, and the container preform M molded in the cavity 123 is taken out.
In the injection molding procedure described above, since the cleaning of the air vent hole 122 is completed by the time the container preform M is taken out, it is not necessary to separately provide a cleaning time for the air vent hole 122, and the production speed is not slowed down.
The cleaning time is usually about 0.5 to 1.5 seconds, but the longer the cleaning time, the more effective the cleaning can be.

In the present invention, the above-mentioned cleaning operation may be performed for each molding cycle in a series of molding cycles starting from the mold closed state of the molding die 110 to opening the molding die 110 and taking out the container preform M. It is preferable in that the air vent hole 122 is suppressed from being contaminated and the container preform molding apparatus 100 is continuously operated for a long period of time.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is possible.
In the above-described embodiment, the method and apparatus for forming the molten material have been described as being applied to the molding of a container preform, but the present invention is not limited thereto. For example, the molding method and device are not limited to the injection molding method and device, but may be a compression molding method and device for molten materials. Further, the molded product is not limited to an intermediate molded product such as a preform, and may be a final molded product. Further, the molten material is not limited to the thermoplastic resin, but may be a thermosetting resin, a metal material, glass, or a composite material thereof.
Further, in the above-described embodiment, it has been described that a molding die that combines a total of four molds, that is, a core mold, two neck split molds, and a body cavity mold, is used. And the shape are not limited to this, and for example, two or three pieces for forming a cavity (cavity), or five or more divided types may be used.

Further, in the above-described embodiment, the core mold is provided with a gas inflow passage, and the neck split mold is provided with a vent groove, an discharge auxiliary groove, and a gas discharge groove, but the present invention is not limited to this, and for example, the neck split mold is provided. The mold may be provided with all of the gas inflow path, the vent groove, the discharge auxiliary flow path, and the gas discharge path. In addition, a vent groove, a discharge auxiliary groove, and a gas discharge groove are provided on one split surface of the ward split mold, but the appropriate air vent hole and discharge auxiliary flow path are combined with the split surface of the other neck split mold. , These grooves may be provided on the split surfaces of both neck split dies as long as they are at the depth of the gas discharge path. Further, the vent groove may be provided not only on the female split type split surface but also on the split type split surface as long as it is suitable for gas discharge. Further, the discharge auxiliary groove (discharge auxiliary flow path) and the gas discharge groove (gas discharge path) may be omitted, and the air vent groove (air vent hole) may be directly passed to the outside of the split mold.
Further, in the above-described embodiment, it has been described that it is preferable to perform the cleaning operation for each molding cycle, but the frequency of the cleaning operation is not limited to this, and for example, the cleaning operation is performed every predetermined number of cycles. Alternatively, the cleaning operation may be performed when a predetermined time has elapsed regardless of the number of molding cycles.

Further, in the above-described embodiment, it has been described that the cleaning gas is supplied in a state where all the molding dies are closed and the molten resin into the molding dies is injected and filled, but the timing of supplying the cleaning gas is different. Not limited to this. For example, as shown in the upper part of FIG. 10, the solidified resin P (preform M) exists in the split mold in which the air vent hole 122 is formed, and the body cavity mold 119 is opened. Even if the cleaning gas G is supplied in this state, the cleaning gas G does not leak to the body cavity mold 119 side, so that the air vent hole 122 can be cleaned while suppressing the supply amount of the cleaning gas G. Further, even if the cleaning gas G is supplied at the stage when the molten resin P flows into the cavity 123 (gate 121), it is between the inlet of the gate 121 and the tip of the injection nozzle or the tip of the hot runner of an injection molding machine (not shown). A large amount of cleaning gas G does not leak from the gaps and the like. Further, even if the cleaning gas G is supplied when the inside of the body cavity mold 123 is filled with the molten resin P, the cleaning gas G is still used in the neck split mold 114a (or 114b) and the body cavity mold 119. It does not leak in large quantities from the gap between the two. When the cleaning gas G is supplied at these early stages, it is preferable to end the supply of the cleaning gas G after the injection filling is completed (more preferably, until the preform M is taken out). If the supply of the cleaning gas G is terminated before the injection filling is completed, the inflow of the molten resin P into the cavity 123 is disturbed, and traces such as air marks remain on the preform M.
Further, the control of the supply and stop of the cleaning gas by the control unit may be linked with the timing of the resin filling control and the mold opening / closing control.

100 ・ ・ ・ Preform molding equipment for containers (molding equipment for molten materials)
110 ・ ・ ・ Molding mold 111 ・ ・ ・ Core mold (male mold)
112 ・ ・ ・ Core base 113 ・ ・ ・ Inner peripheral surface forming part 114a, 114b ・ ・ ・ Neck split mold (female split mold)
115a, 115b ・ ・ ・ Divided surface 116a, 116b ・ ・ ・ Neck forming part 117 ・ ・ ・ Vent groove 117a ・ ・ ・ Discharge auxiliary groove 117b ・ ・ ・ Discharge auxiliary flow path 117c ・ ・ ・ Gas discharge groove 117d ・ ・ ・ Gas Discharge path 118 ・ ・ ・ Gas inflow path 119 ・ ・ ・ Body cavity mold (female mold)
120 ・ ・ ・ Body forming part 121 ・ ・ ・ Gate 122 ・ ・ ・ Air vent hole 123 ・ ・ ・ Cavity 130 ・ ・ ・ Gas supply mechanism M ・ ・ ・ Preform for container (molded product)
Ma ・ ・ ・ Body part Mb ・ ・ ・ Neck part P ・ ・ ・ Resin (molten resin, material, molten material)
K ・ ・ ・ Residual air G ・ ・ ・ Cleaning gas

Claims (8)

A gas inflow path and an air vent hole leading to the cavity are formed on at least one of the divided surfaces which are the abutting surfaces of the divided molds of the molded mold composed of a plurality of divided molds forming a cavity by mold closing. It is a molding method of a molten material in which a material melted by heating is filled in the cavity of the molded mold closed by using the molding die including the split mold, and the molded product is molded by cooling and solidifying.
With the molding mold closed and the material present in the cavity, cleaning gas is supplied from the gas inflow passage to the air vent hole and discharged from a location different from the gas inflow passage .
The injection pressure of the cleaning gas is 0.3 MPa or more and 5.5 MPa or less.
A method for molding a molten material, wherein the injection time of the cleaning gas is 0.5 seconds or more and 1.5 seconds or less . The method for forming a molten material according to claim 1, wherein the cleaning gas is supplied during the step of cooling the material in the cavity. The method for molding a molten material according to claim 1 or 2, wherein the supply of the cleaning gas is stopped by the time the molded product is taken out from the molding mold. The molding mold includes a female mold and a male mold, the female mold includes a plurality of female split molds, the cavity is formed by the female mold and the male mold, and the cleaning gas is the gas. The method for forming a molten material according to any one of claims 1 to 3, wherein the female split molds are introduced into the air vent holes formed on at least one of the divided surfaces of the female split molds from the inflow path. The method for molding a molten material according to any one of claims 1 to 4, wherein the heat-melted material is injection-filled in the cavity. The method for molding a molten material according to any one of claims 1 to 5, wherein the material is a synthetic resin. The method for molding a molten material according to claim 6, wherein the synthetic resin is a thermoplastic resin, and the preform of the container is molded by the molding method. A molten material molding apparatus for producing a molded product by the method for molding a molten material according to any one of claims 1 to 7.
The molten material molding apparatus has a gas supply mechanism for supplying the cleaning gas to the air vent hole.
The gas supply mechanism is a control unit that controls the supply timing of the cleaning gas so as to supply the gas to the air vent hole between the start of the flow of the molten material in the cavity and the removal of the molded product. A molding apparatus for a molten material, characterized in that

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