JPS6233623A - Apparatus for molding plastic hollow container - Google Patents

Abstract

PURPOSE:To obtain a hollow container molding machine capable of altering a uniform-heating time according to the wall thickness of a preform, by providing a plurality of uniform-heating wheels for feeding a preform and selectively combining said wheels. CONSTITUTION:When a preform P has a large wall thickness, a uniform-heating wheel 5 for a short pass is preliminarily detached, the preform P is heated by a heating wheel 1 to be supplied to the blow mold 8 of a blow wheel 7 through uniform-heating wheels 3, 4. Therefore, a uniform-heating time becomes longer and the inner and outer surfaces of the preform uniformly heated even if the wall thickness is large. In the case of a thin-walled preform P, the uniform-heating wheel 5 for the short pass is preliminarily arranged and the preform P is heated by the heating wheel 1 and supplied to the mold 8 of the blow wheel 7 through uniform-heating wheels 5, 4 to shorten the uniform-heating time.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an apparatus for biaxially stretching a thermoplastic resin such as polyethylene terephthalate to form a hollow plastic container.

Prior Art When molding containers such as hollow bottles using thermoplastic resins such as polyethylene terephthalate, polyethylene, and polypropylene, it is necessary to improve their physical and mechanical properties as described in, for example, JP-A No. 54-93062. In order to do this, a preform is molded by injection molding or Pig extrusion molding, etc., and then it is reheated to the appropriate temperature for 1:% normal stretching, and then inserted into a blow molding mold and formed by stretching rond and pressurized fluid. is being carried out. When heating the preform to the fully variable stretching temperature a, if heating is performed from the outer surface of the preform using an electric heater or the like, a temperature difference will occur between the inner and outer surfaces of the hub form immediately after heating because the preform is a narrow cylinder with a bottom. If stretching is carried out in a state where there is a temperature difference between the inner and outer surfaces of the preform, problems such as non-uniform wall thickness will occur.

Therefore, conventionally, a soaking time is provided to balance the temperature of the inner and outer surfaces of the preform before inserting it into the blow mold after heating.

Problems to be Solved by the Invention However, the time it takes for the temperature of the inner and outer surfaces to reach a uniform state (soaking time) naturally varies depending on the thickness of the preform, but the conventional method described above has problems due to the structure of the device. Since only a certain soaking time can be provided at all times, the molding speed may be regulated by the soaking time.

Therefore, it is preferable to be able to appropriately select the soaking time while setting each molding speed to the maximum, but since the soaking time is constant in the above case, this is not possible. , was invented to solve the above problems, and the purpose is to provide a new hollow container molding machine that can change the soaking time depending on the wall thickness of the preform. Means for achieving the above object will be explained based on drawings corresponding to embodiments.

The present invention provides a plurality of soaking wheels 3. which convey a preform P between a heating wheel 1 and a plow wheel 7.
4.5, and by selectively combining the soaking wheels, the conveyance path of the C preform can be changed, and the soaking time can be set in two or more stages.

In the case of a preform P with a working thickness, if the short-pass soaking wheel 5 is removed in advance, the heating wheel 1
The heated preform P is supplied to the blow molding die 8 of the blow wheel 7 via the soaking wheel 5 and the soaking wheel 4. Therefore, the soaking time becomes longer, and even if the preform P is thick, the heat is soaked both inside and outside.

In addition, in the case of a thin preform P, if a short-pass soaking wheel 5 is installed, the preform P heated by the heating wheel 1 will be heated by the short-pass soaking wheel 5 and the soaking wheel. Blow wheel 7 through 4
is supplied to the molding die 8. Therefore, soaking strip P for thin-walled preforms with short soaking time! Embodiment in which soaking time for Pft pedaling can be set Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

Reference numeral 1 denotes a heating wheel for the preform, and holding parts for receiving and rotatably holding the mandrel that supports the entire preform are arranged at equal intervals on its surface. It is designed so that it is heated by heaters 2 disposed around it while rotating along with the rotation. Reference numeral 3.4.5 is a heat equalizing wheel for equalizing heat between the inner and outer surfaces of the preform, and holding portions are arranged at equal intervals on the circumferential surface of the wheel, similar to the heating wheel. As shown in the figure, the soaking wheel 3 is arranged to receive the preform from the heating wheel 1 and pass it to the soaking wheel 4,
On the other hand, the soaking wheel 5 forms a short I, and its outer casing is smaller than the heat soaking wheel 3.4, and can be removed at any time so as to relay the heating wheel 1 and the heat soaking wheel 4. It is installed in Therefore, in this embodiment, in the case of a thick-walled preform, the soaking wheel 5 is removed and the preform P is conveyed from the heating wheel 1 to the soaking wheels 3 and 4, and in the case of a thin-walled preform, By installing the soaking wheel '5, the preform is conveyed from the pH heating wheel 1 through the soaking wheel 5 to the soaking wheel 4. .

6 is a conveyance wheel that relays between the soaking wheel 4 and the blow molding die 8 of the blow wheel 7. Also, 9.12
are conveyance wheels that relay between the blow wheel 7 and the supply/discharge wheel 10 and between the supply/discharge wheel 10 and the heating wheel 1, respectively. Furthermore, 11 is a conveyor for carrying out the molded hollow container W, and 13 is a star wheel that receives the preform P from the chute 14 and supplies it to a supply/discharge wheel at equal intervals.

The hollow container forming machine constructed as described above operates as follows.

A preform P molded by injection molding, vibrator extrusion molding, or the like is supplied from the chute 14 via the star wheel 13 to a mandrel held by the supply/discharge wheel 10. The preform P supported by the mandrel is supplied together with the mandrel from the supply/discharge wheel 10 via the conveyance wheel 12 to the deep holding part of the heating wheel I, and is heated by the heater 2 while rotating with the heating wheel 10 rotations. When the preform P has a thick wall, the soaking wheel 5 is removed in advance, so that the preform passes through a long course from the heating wheel 1 to the soaking wheels 3 and 4, and the inner and outer surfaces of the preform are heated in between. The temperature becomes equilibrium. Also, if the preform P is thin, the soaking wheel 5
By installing this, the soaking time is shortened because the soaking time is conveyed to the soaking wheel 4 via the soaking wheel 5. Thereafter, the preform in a soaked state is supplied to a blow molding mold 8 by a conveyor wheel 6, and biaxially stretched by a well-known method. The biaxially stretched plastic hollow container is taken out from the mold 8 by a conveyor wheel 9, and
It is separated from the mandrel by the supply/discharge wheel 10 and discharged onto the discharge conveyor 11 .

In the above embodiment, a total of three soaking wheels are provided so that the soaking time of each stage can be selected, but for example, there is an additional removable relay time between the soaking wheel 3 and the heating wheel 1. By providing a soaking wheel that relays the heat soaking wheel 3 and the heating wheel at the front of the heat soaking wheel and the heating wheel in the rotational direction, various aspects can be achieved, such as being able to obtain three stages of soaking time. However, the present invention is not limited to the above embodiments.

Effect As a result of the present invention configured as described above, the soaking time can be selected depending on the thickness of the preform, so the preform is supplied to the blow molding die at the point of stretching 11 when the temperature difference between the inner and outer surfaces of the preform has disappeared. can do. Therefore,
Since the molding speed is not restricted by the preform soaking time and can be molded at the maximum speed for each preform, the production efficiency can be increased. In addition, the present invention has remarkable effects compared to conventional ones, such as the simple structure of changing the soaking time by simply attaching and detaching the soaking wheel.

[Brief explanation of drawings]

The drawing is a perspective view of an embodiment of the plastic hollow container molding machine according to the present invention. l: Heating wheel 2: Heater 3.4.5; Soaking wheel 6.9.12: Conveyance wheel 7: Blow wheel 8 Ni blow mold 10:
Supply/discharge wheel procedure amendment (voluntary) September 13, 1985 Michibe Uga, Commissioner of the Patent Office 1, Indication of case 1985 Patent Application No. 173166 2, Name of invention Plastic hollow container forming device 3, Amendment Relationship with the case of a person who does
(376) Toyo Seikan Co., Ltd. Representative Yoshibe Takasaki 4, Agent 5 Number of inventions to be increased by the amendment None 6 Subject of the amendment ``Detailed description of the invention'' column 7 of the specification, Contents of the amendment

Claims (1)

[Claims] 1) In a molding device that biaxially stretches a thermoplastic resin to mold a hollow container, the heated preform is conveyed between a heating wheel and a blow wheel, while the inner and outer surfaces of the preform are conveyed between a heating wheel and a blow wheel. A plurality of soaking wheels are provided to balance the temperature of the preform, and by selectively combining the soaking wheels, the soaking time of the preform can be set in two or more stages. Plastic hollow container molding equipment. 2) The plastic hollow container molding apparatus according to claim 1, wherein a heat soaking wheel forming a short bath among the heat soaking wheels is detachably provided.