JPS61185429A - Method and apparatus for producing bottle - Google Patents

Abstract

PURPOSE:To produce a bottle with a highly accurate wall thickness distribution by blowing a gas circumferentially to the section of a parison having a relatively high temperature where molding is effected. CONSTITUTION:A bottomed parison 1 of a polyester at a higher temperature state than the glass transition point of the involved resin is taken out from an injection mold, the holding ring 1a is held by a holder 3 and the molding section 2 is inserted into a cooling block 5. A cooling apparatus 4 is provided with a cooling block 5 and a driving mechanism 6 that will drive the cooling block 4 vertically in a prescribed timing. A pressurized air 18 in a high pressure chamber 13 flows via slits 16a, 16b into a low pressure chamber 15, whereas the relatively low pressure air 21 in the low pressure chamber 15 is once throttled at a throttling section 19 and is blown from a blowing outlet 20 to cool the molding section 2 of the parison 1 circumferentially uniformly to a prescribed temperature that is equal to or higher than the glass transition point.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for manufacturing bottles, and more specifically, after adjusting the temperature of the molding section of a polyester bottomed jason, the molding section is stretched and blown. This invention relates to a method and apparatus for molding and manufacturing bottles.

(Prior art) Japanese Patent Publication No. 53-22096 discloses that an injection mold,
A technology has been proposed in which after forming a bottomed I4 litho from a molten resin, this A4 litho is heated to a required temperature from the inside and outside with an electric heater on a heating stage, and then this parison is stretch blow molded to produce YJR). (Problems to be Solved by the Invention) In recent years, the contents stored in polyester resin stretch blow molded bottles, especially polyethylene terephthalate biaxial stretch blow molded bottles, and the shape of the bottle (for example, the shape of the bead) have become increasingly important. (depending on settings, etc.) have diversified, and as a result, there are increasing cases where bottle wall thickness distribution is required with extremely high precision. For example, in the case of bottles for storing carbonated drinks, beer, etc., it is necessary to prevent deformation and breakage due to positive internal pressure, and to have gas barrier properties (
In order to improve the resistance (particularly against carbon dioxide gas), it is necessary to prevent wall portions that are locally thinner than a predetermined thickness from occurring.
On the other hand, from the viewpoint of material costs, it is necessary to avoid creating wall sections that are thicker than necessary. Also, when hot-picking or removing gears, similar precautions must be taken to prevent deformation due to negative internal pressure.

In other words, the shape and dimensions of the bottle, material strength, and internal pressure.

Depending on the required gas barrier properties, the shoulder of the bolt,
It is desirable that the wall thickness of each part such as the body and the bottom be set to a predetermined value with high accuracy. The wall thickness of each part of this bottle, that is, the stretchability is p4' immediately before stretch blow molding.
It is largely controlled by the temperature of the part of the litho corresponding to the bolt part (this temperature is the moldable temperature, ie, the temperature above the glass transition temperature of the polyester).

That is, in order to control the wall thickness distribution of the bolt to a predetermined value with high precision, it is necessary to adjust the temperature distribution of the parison immediately before stretch blow molding with high precision.

However, depending on the conventional heating method, it is difficult to adjust the temperature distribution of the parison with high precision. Therefore, stretch blow-molded polyester yj? has a wall thickness distribution that is controlled with high precision. ) It was difficult to produce a standard product.

(Objective of the Invention) An object of the present invention is to provide a method and apparatus for manufacturing polyester with a highly accurate wall thickness distribution by stretch-blow molding from polyester bottomed/quadrature.

(Structure of the Invention) The present invention provides a method for manufacturing a bottle by stretch-blow molding a molded part of a polyester bottomed i4 lison, in which the molded part is higher than the glass transition point of the polyester than an injection mold. Take out the parison at a high temperature,
A bottle characterized in that stretch blow molding is immediately performed after the molded part of the taken out parison is simultaneously blown with gas from the circumferential direction to cool the molded part to a predetermined temperature above the glass transition point. The present invention provides a method for manufacturing.

Furthermore, the present invention provides an apparatus for manufacturing a bottle by stretch-blow molding a molded part of a polyester bottomed i4 lison, the apparatus comprising: a through hole into which the molded part can be inserted; an annular high pressure chamber surrounding the through hole; A guide hole extending substantially tangentially to the annular high-pressure chamber for introducing pressurized gas into the annular high-pressure chamber, and a plurality of discontinuous slits located on the radially inner side of the annular high-pressure chamber along the circumferential direction. an annular low pressure chamber connected to the annular high pressure chamber;
and the molded part connected to the annular low-pressure chamber through the annular restrictor 9 and expanded radially inward to have a trapezoidal cross section and inserted into the through hole, and the molded part The present invention provides an apparatus for manufacturing yjr) characterized by comprising a cooling block having an annular gas outlet for cooling the yjr to a predetermined temperature.

(Example) In FIG. 1, l is a bottomed nozzle made of polyester, for example polyethylene terephthalate;
a is a retaining ring. Bottomed zf The part below the retaining ring 1a of the litho 1 is the molded part 2, which includes an upper part 2a of the molded part 2, a cylindrical part 2b below which becomes slightly smaller in diameter toward the bottom, and a bottom part 2c. However, the shoulder of the bottle (see Figure 6) formed by stretch blow molding,
These are the parts that should become the torso and bottom.

The bottomed A41Json 1 is taken out from the injection mold at a relatively high temperature higher than the glass transition point of the resin,
Immediately, the retaining ring la, held by the holder 3, is carried in a hanging state to the cooling device 4, and as shown in the figure, the molded part 2 is inserted into a cooling block 5, which will be described later, and is held in that position.

The cooling device 4 includes a cooling block 5 and a drive mechanism 6 that moves the cooling block 5 up and down at predetermined timing. The drive mechanism 6 includes a vertical worm gear 7 that engages with the cooling gear 5, a stepping motor 8, and a gear 9 for transmitting the rotation of the stepping motor 8 to the worm gear 7. I
It is equipped with O. That is, the cooling block 5 is configured to move up and down via the worm gear 7 according to the rotation of the stepping motor 8.

The cooling plate 5 is made of aluminum alloy, for example, and has a slight gap 11 as shown in FIGS. 2 and 3.
A through hole 12 with a circular cross section into which the molded part 2 can be inserted with a gap width W of preferably 3 to 10, an annular high pressure chamber 13 surrounding the through hole 12, and an annular high pressure chamber 13 surrounding the through hole 12. An annular low pressure chamber 15 is separated by a barrier section 14 and is located radially inside the high pressure chamber 13.

As shown in FIGS. 3 and 4, the upper end of the barrier portion 14 has a plurality of, preferably six or more (eight in the figure) sleeves 16a, preferably equally spaced along the circumference. It is set in. As clearly shown in FIG. 3, the lower end of the barrier portion 14 is also provided with a plurality of slits 16b, preferably at alternate positions with the upper slits 16a.

In addition, the high pressure chamber 13 is connected to a source of pressurized gas (usually air, hereinafter referred to as air), which is not shown.

A plurality of (two in the figure) guide holes 17 are provided to guide pressurized air 18 through a flow solenoid valve. Each guide hole 17 is symmetrical about the center and extends substantially tangentially to the high pressure chamber 13. The pressurized air 18 is formed in such a manner that the flow of the pressurized air 18 is as uniform and smooth as possible within the high pressure chamber 13. That is, a substantially uniform primary pressure (for example, 1 kg/ff12) is generated within the high pressure chamber 13 along the circumferential direction.

The pressurized air 18 in the high pressure chamber 13 is supplied to the sleeve) 16a.

16b into the low pressure chamber 15, the sleeve) 16
m and 16b are formed at equal intervals along the circumferential direction as described above, and an annular throttle part 19 to be described later is provided for temporarily storing the air in the low pressure chamber 15. , a substantially uniform secondary pressure (for example, 0.5 kg/cn2) is generated in the low pressure chamber 15 along the circumferential direction.

C1. inside the low pressure chamber 15 in the radial direction. An annular constriction portion 19 and an annular air outlet 20 are provided, and the outlet 20 expands radially inward to have a trapezoidal cross section. Low pressure chamber 1
The relatively low-pressure air 21 of No. 5 is squeezed by the constriction part 19, and then blown out from the blow-off port 20, along the circumferential direction of the forming part 2 of No. The part of the molded part 2 inside the through hole 12 is cooled substantially uniformly along the circumferential direction to a predetermined temperature equal to or higher than the glass transition point of the polyester. Since the air 21 has a relatively low pressure and the outlet side of the blow-off port 20 is widened, there is no risk of deformation of the molded part 2 when the air 21 hits the molded part 2.

The degree of cooling of a specific portion in the axial direction of the molding section 2, that is, the temperature after cooling, is adjusted by the amount of air 21 blown per unit time and the blowing time from the cooling process 5 to the specific portion.

FIG. 5 shows an example of the above adjustment, where ■, ■, ..., ■ on the vertical axis indicate the setting position from above,
The numbers on the left side, for example the top number, are the setting positions ■ and 0
This indicates that the distance between them is 10m+. The top setting position ■ is, for example, Cooling Pro.

The upper surface 5m (Fig. 1) of the ring 5 is in almost contact with the retaining ring la, and the lowest setting position is such that the lower surface 5b is at approximately the same level as the lower surface of the bottom 2c of the molding part 2. determined in position. Qlt..., Q6 are air flow rates, which are determined by adjusting the opening degree of a flow rate solenoid valve provided between the guide hole 17 and the pressurized air temperature using an input signal to the controller. vl..., Ma4 is,
This indicates the descending speed or ascending speed of the cooling block 5 (in FIG. 5, a downward arrow indicates descending and an upward arrow indicates ascending), and is determined by the rotational speed and rotation direction of the stepping motor 8. tl+..., ts is the stop time of the cooling professional 5, and the stepping motor 8
equal to the stop time of

In the figure, in the sections marked ■ and ■, the cooling
is lowered at a speed of vl, and air is blown out from the air outlet 20 at a flow rate of Q2. ■, ■ intervals, and ■, ■
In the section, the flow rate of air blowing out is the same in Q-factor, but the descending speed is different in both v2 and v3. In the setting position ■, the cooling block 5 is operated for a time of 1. stop,
During that time, air with a flow rate of Q3 is blown out. After that, the cooling pro, Ri5, rises to position ■ at the speed of v4, while Q1
A flow rate of air is blown out.

Although the explanation will be omitted hereafter, in the same manner as above, the cooling block 5 is
is raised, lowered, stopped, and air is blown out.

After the cooling block 5 reaches the lowest position (■) and a predetermined amount (Q5) of air has been blown out, the parison l is taken out from the cooling block 5, and then the cooling block 5 stops blowing air and moves to the top position. Return to position ■. In the case shown, the intervals ■～■, ■～■.

In ■~■ and ■~O, the time during which air is blown is relatively short, and the sections ■~■ are relatively long.

Note that if it is desired to cool only a specific portion of the molding section 2, the cooling block 5 does not need to be moved up and down.

The /4 Lithon 1 taken out from the cooling block 5 is immediately transferred to a stretch blow mold (not shown) and biaxially stretch blow molded by a known method to form a bottle (2 in Figure 6).
2).

(Effects of the Invention) According to the method of the present invention, gas is simultaneously blown onto the molded part of the parison at a relatively high temperature from the inner peripheral direction.
It is easy to cool each part of the molding section substantially uniformly in the circumferential direction to a predetermined temperature suitable for stretch blow molding that is above the glass transition point, and it is easy to adjust the temperature to be cooled. Adashi.

Therefore, it is possible to easily and reliably adjust the thickness distribution of the formed &) hole.

Further, according to the apparatus of the present invention, each part of the molding section of the p4 litho, which is relatively high temperature, can be reliably cooled to a predetermined temperature substantially uniformly in the circumferential direction.Experimental examples will be described below. .

The outer diameter of the upper part 2a in contact with the lower surface of the retaining ring 1a is 26.26 mm, the outer diameter of the smallest diameter part of the cylindrical part 2b is 23.28 mm, the height of the molded part 2 is 115.04 mm, A bottomed crison 1 made of polyethylene terephthalate having a thickness of 3.7 m was formed by injection molding, immediately taken out of the mold, and set in a cooling device 4 as shown in FIG. When the temperature of the molded part 2 was measured with a radiation thermometer immediately after setting, it was 120°C near the upper end of the upper part 2a, and the temperature decreased as it went downward, and was 90°C near the lower end of the cylindrical part 2b. there were.

The thickness of the cooling block 5 used in the cooling device 4 was 20 mm, the height of the opening 20a of the outlet 20 was 12 mm, and the width W of the gap 11 was 8.6 mm. 41) Immediately after setting the parison 1, move the cooling block 5 so that its lower surface 5b is located 960+m++ above the lower surface of the bottom 2C of the parison, and while keeping it in that position, air is supplied to the air outlet 20. The molded part 2 was cooled for 3 seconds by blowing out water. The primary pressure of the high pressure chamber 13 and the secondary pressure of the low pressure chamber 15 were 1 kl/cm2 and 0.3 kg/an2, respectively, and the cooling air volume was 150 NA, 4.

Immediately thereafter, Clison 1 was sent to a stretch blow mold and subjected to biaxial stretch blow molding to produce a bottle 22 having the shape shown in FIG. ? The total height of the torle 22 was 200 m, and as shown in the figure, a thick portion 22&1 was formed approximately at the center of the body portion 22a in the height direction. The thickness of the thick portion 22a is 0. :3 m, and the thickness of the other body part was 0.2 m. The height of the thick part 22a1 is 80 m, and the height from its lower end to the bottom end is 50 m.
■It was.

For comparison, ・Yarison 10 forced cooling was performed.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is a cross-sectional view taken along the line ■-■ of FIG. Figure 3 is a longitudinal sectional view taken along line ■-m in Figure 2,
The figure is a cross-sectional view taken along the line ■-■ in Figure 3, Figure 5 is a diagram showing an example of a schedier that cools a parison using the cooling block in Figure 2, and Figure 6 is a method according to the present invention. 1 is a partially cutaway front view of an example of a bottle manufactured by. DESCRIPTION OF SYMBOLS 1... Bottomed Clison, 2... Molding part, 5... Cooling pro, Ri, 12... Through hole, 13... Annular high pressure chamber, 15... Annular low pressure chamber, 16ay16b...slit, 17...conducting hole, 18...pressurized air (pressurized gas), 19...annular constriction part, 20...annular air outlet, 22...&tor . Figure 1 Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) In a method of manufacturing a bottle by stretch blow molding a molded part of a polyester bottomed parison, the parison is heated in a relatively high temperature state higher than the glass transition point of the polyester using an injection mold. The molded part of the parison is taken out, and gas is simultaneously blown from the circumferential direction onto the molded part of the taken out parison to cool the molded part to a predetermined temperature above the glass transition point, and then stretch blow molding is immediately performed. A method of manufacturing bottles. (2) An apparatus for manufacturing a bottle by stretch blow molding a molded part of a polyester bottomed parison, the apparatus comprising: a through hole into which the molded part can be inserted; an annular high pressure chamber surrounding the through hole; A guide hole extending substantially tangentially to the annular high-pressure chamber that guides pressurized gas into the high-pressure chamber; An annular low-pressure chamber connected to an annular high-pressure chamber, and an annular low-pressure chamber connected to the annular low-pressure chamber through an annular constriction section, expanding radially inward to have a trapezoidal cross section, and the molded section inserted into the through hole. A bottle manufacturing apparatus comprising a cooling block having an annular gas outlet for blowing gas to cool the molded part to a predetermined temperature.