JPS6350290B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for rotary blow molding hollow glass articles by blowing air blowing near the bottom of the parison, and in particular, the present invention relates to a method for rotary blow molding a hollow glass article by ejecting blow air near the bottom of the parison. First, a homogeneous hollow glass article is obtained by preventing overcooling of the upper end and body portion.

[Prior art] Comparatively thin hollow glass articles such as glass cups for dining tables and beakers can be made using the press-and-blow method, in which a gob is embossed to form a parison and then turned, or the blowing method is used, in which the gob is blown into a parison and then turned. It is carried out using the and blow method. In either case, the neck part of the parison is grasped, cut into two parts, and placed in a mold (paste mold) with a paste layer on the inner surface, and while the parison and neck ring are rotated, blow air is blown from the blow head on the neck opening side. Now, to describe the press-and-blow molding machine, as shown in FIG. A pair of cavities 7 are provided near a sleeve 6 formed at the center of the interior of the rotating body 3. In this space 7, a claw 8 constituting a neck ring is rotatably installed, and a sleeve 6
A blow head 10 having an ejection port 11 and an exhaust port 12 is provided on the upper part of the sleeve 6, and a paste mold 13 divided into two parts is provided below the sleeve 6.
The bottom mold 14 is placed. A coil spring 15 is provided on the lower side of the claw 8 to impart a closing tendency to the claw,
The top of the claw has a neck ring opening/closing mechanism (not shown).
has been established. The blow head 10 does not rotate, and when blowing is in close contact with the upper end of the sleeve 6 as shown in the figure, blowing air into the molded body, and when not blowing, it is separated from the upper end of the sleeve and placed on standby. In FIG. 1, the rotational direction arrow above the blowhead 10 indicates the rotational direction of the sleeve 6 and the glass article 17, which rotate synchronously with the rotating body 3.

After cooling the parison bottom, the blow air from the spout 11 is reversed along the curvature of the bottom inner wall, and
While rising, the body is cooled and discharged from the exhaust port 12. The parison expands due to the increase in internal pressure, takes the same shape as the mold, and after the glass surface hardens,
The paste mold is opened and the glass article is removed.

[Problems to be Solved by the Invention] In both press-and-blow molding and blow-and-blow molding, the distance between the spout 11 at the top of the sleeve and the neck portion of the glass article 17 is long. When the air is ejected from the outlet 11, the inside of the hollow molded product is ventilated only near the ejection port, and there is almost no ventilation to the lower part and lower side of the glass article 17. The side cooling effect is not sufficient. On the contrary, since cooling of the mold in the vicinity of the upper end and its contact area, which does not require much cooling, is accelerated, the glass article is more likely to be damaged due to overcooling. Therefore, it is generally used with the exhaust port 12 closed or slightly open. Therefore, a blower with a high pressure of Kg/cm ² is used for the purpose of increasing the pressure inside the molded body. The higher the internal pressure is, the faster the blowing air will be, and the closer the contact between the glass article 17 and the paste mold 13 will be. Therefore, the curing speed of the glass becomes faster, and the blowing time can be shortened accordingly. On the other hand, the internal pressure increases and the paste layer is damaged due to excessive pressure contact with the mold.
Streaks may be transferred to the glass surface, or the slippage between the mold and the glass may become poor, resulting in twisting due to round-blowing, which significantly deteriorates the quality of the product. This can be suppressed by frequently replacing the molds, but there is a problem in that no improvement in productivity can be expected.

[Means for Solving the Problems] The present invention provides blow air blowing toward the bottom of the parison from the tip of a nozzle that extends from the blow head to near the bottom of the parison in round blow molding, so that the blow air is not applied to the hollow glass article being round blown. A swirling flow is generated, and the lower and lower parts of the article are raised in the circumferential direction while being cooled, and are exhausted from the outlet of the blowhead.

[Function] In the present invention, the blow nozzle is suspended beyond the neck of the glass article without rotating with the parison to be rotary-blown, and the air from the blow nozzle rises through the lower part and side of the hollow glass article. During this process, a relative rotation is applied, and this swirling flow cools the glass article in the circumferential direction while discharging it. Therefore, uniform cooling can be performed in the circumferential direction and in the vertical direction without causing partial supercooling. Ru. Further, in the present invention, the pressure within the molded body is kept relatively low during blowing without increasing it, so there is no excessive pressure on the mold of the glass article, and no striations or twists occur.

[Example] Next, the present invention will be specifically described with reference to the drawings.
Figures 2 and 3 show the case where the present invention is applied to a rotary blow molding device using a press-and-blow method, in which 1 is a machine frame, 2 is a bearing, 3 is a rotating body, and 4 is a rotating body. A gear formed on the outer periphery of the body, 5 a pinion that engages with the gear and rotates the rotating body, 6 a sleeve provided at the center inside the rotating body, 7 a hollow space formed near the sleeve, and 8 inside the hollow space. 9 is an O-ring,
10 is a blow head, 13 is a paste mold,
14 is a bottom mold. A nozzle 19 that reaches near the bottom of the parison when the mold is closed is provided in the jet passage 18 of the blow head 10, and a jet nozzle 20 is opened downward at the tip thereof.
Note that in both FIGS. 2 and 3, the rotational direction arrow above the blowhead 10 indicates the rotational direction of the sleeve 6 and the glass article 17, which rotate synchronously with the rotating body 3, as in the case of FIG.

FIG. 2 shows that the parison 16, whose neck portion is held by the lower end of the sleeve 6 and the claw 8, is rotated as shown by the arrow by the rotation of the pinion 5, and the paste mold 1
3 indicates an open state. Rotating parison 1
6 will droop, so immediately paste the mold 13.
is closed, and then the blow head 10 is lowered.
When the blow head 10 contacts the upper end of the sleeve 6 and is sealed, the internal pressure of the parison becomes slightly higher than the external pressure and begins to swell due to the blow air jetted toward the bottom of the parison from the jet nozzle 20 at the tip of the nozzle advanced near the bottom of the parison 16. As the blowing continues, the paste mold 13 swells into almost the same shape as the inner shape of the paste mold 13, as shown in FIG. When the glass surface begins to harden a little, the blowing air pressure is further increased to improve the accuracy of the product's external shape.

The ejected air cools the bottom of the parison, then turns around along the curvature of the inner wall of the bottom, and cools the body of the hollow glass article while rising. The air rotates relative to the article being blown, and as it rises, the article is cooled uniformly in the circumferential direction by a swirling flow, and then flows out through the exhaust port 12 of the blow head. The increase in air volume further promotes internal ventilation, and the cooling rate of the inner surface, especially the lower and lower parts, becomes faster, and the glass article is cooled from both the inside and outside. In this way, the blowing time is reduced by 15-25% compared to conventional methods without any loss in quality. Generally, the internal pressure of the hollow glass mentioned above is
It is best controlled within the range of 50 to 500 mmH ₂ O, preferably 100 to 300 mmH ₂ O, and by lowering the initial blow pressure and gradually increasing the internal pressure as the outer surface hardens, the external shape accuracy is good. , it is possible to obtain a high-quality product with a glossy outer surface.

In this method, if the blowing air speed is too high, a dent will be created in the inner bottom of the product, so the wind speed must be set to an appropriate level. For example, it is desirable to set it to 3m/sec or less. The relationship between the jet nozzle diameter and the exhaust port is a factor that determines this wind speed, and as mentioned above, the internal pressure is 500 mm.
Since H ₂ O or less is desirable, the jet nozzle diameter D ₁ and exhaust port diameter D ₂ should be set so that D ₁ ≧ D _2.The larger D ₂ is, the higher the jet speed and the higher the cooling speed. Become.

[Effects of the Invention] As described above, according to the present invention, the blow air is ejected toward the bottom of the parison from the nozzle tip extending from the blow head to near the bottom of the parison that rotates on its own axis, and the blow air creates a swirling flow to the hollow glass article that is being blown. This generates heat and discharges it from the exhaust port of the blowhead while cooling the lower part and lower side, so the cooling effect is uniform throughout the circumference of the hollow article, preventing partial overcooling of the upper end as in the conventional case. be done. In addition, by not increasing the rotary blow molding pressure, it is possible to suppress the occurrence of streaks and twists during molding, and it is possible to easily mold high-quality hollow products with good external shape accuracy and excellent outer surface gloss.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an apparatus for carrying out the conventional rotary blow molding method, Fig. 2 is a cross-sectional view of the apparatus for carrying out the method of the present invention in the mold open state, and Fig. 3 is the mold closed state in Fig. 2. FIG. 1...Machine frame, 2...Pairing, 3...Rotating body, 4...
Gear, 5...pinion, 6...sleeve, 7...vacancy,
8...Claw, 9...O-ring, 10...Blow head,
11, 20... Ejection port, 12... Exhaust port, 13... Paste mold, 14... Bottom mold, 15... Coil spring, 16... Parison, 17... Glass product, 18
...Ejection path, 19...Nozzle.

Claims (1)

[Claims] 1 In a method of blow-molding a hollow glass article by blowing blow air into the inside of a parison whose neck portion is gripped, blow air is jetted toward the bottom of the parison from the tip of a nozzle that extends from the blow head to near the bottom of the parison. A method for manufacturing a hollow glass article, which is characterized in that a relative swirling flow is generated in a blow air with respect to the hollow glass article, and the lower part and lower side of the hollow glass article are raised while being cooled, and the air is exhausted from an exhaust port of a blow head. Law.