JPS63134220A - Control method and device for blow molding machine - Google Patents

Abstract

PURPOSE:To control the pressure of pressurized fluid effectively and reduce the noise generated when discharging pressurized fluid out of a parison by controlling the pressure of pressurized fluid blow into the parison at given pressures in several stages. CONSTITUTION:After driving in a blowing nozzle 6 in a parison 2, pressurized air discharged out of the blowing nozzle 6 is blown in with the pressure pH (4-10 kg/cm<2>) necessary to fix the parison 2 by pressure on the surface of a cavity for 2-6 seconds. A hollow product 7 is formed along the surface of the cavity and cooled. Then, the pressure of said air is reduced before exhausting, and the pressure PL (2-5 kg/cm<2>) to be able to maintain the shape of the hollow product 7 is blown in for 3-10 seconds. The hollow product 7 is further cooled down. By controlling pressurized air blown into the parison 2 as above-said, the blowing pressure is always controlled to minimum. Thus energy is saved and the noise of pressurized air when discharged into atmosphere can be reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method and apparatus for controlling a blow molding machine, and more particularly, the present invention relates to a method for controlling a blow molding machine and a device therefor. The present invention relates to a method for controlling a blow molding machine and an apparatus therefor, which enable efficient use of pressurized fluid.

[Conventional technology]

BACKGROUND ART Known conventional techniques relating to blow molding machine control methods and apparatuses include those described in Japanese Patent Application Laid-open No. 59-176024 and Japanese Patent Application Laid-Open No. 60-64824.

To briefly explain the description in the above publication, JP-A-59-17
Publication No. 6024 describes a method for controlling mold clamping force of a blow molding machine. That is, a first stage in which the mold clamping force is relatively small until the mold comes into contact with the parison, a second stage in which the mold clamping force necessary for cutting off the end of the parison by the mold is applied, and It is described that the mold clamping force is controlled in three stages, including a third stage in which a mold clamping force is applied to counteract the pressure of the gas blown into the mold.

Furthermore, Japanese Patent Laid-Open No. 60-64824 discloses that during the formation of the parison, the parison is expanded outside the mold by blowing air into the parison, and then the mold is closed and sufficient pressure is applied to the parison. It has been described that containers with complex shapes are formed by blowing, and in this case,
It is stated that low pressure air (for example 0.6 bar) is blown in when the parison is expanded outside the mold, and high pressure air (for example 7 bar) is blown in when the parison is expanded inside the mold.

[Problems to be solved by the invention] However, from the viewpoint of
Although there is mention of saving energy by controlling the clamping force, there is no suggestion of controlling the pressure of the pressurized fluid blown into the inside of the parison in the closed mold. Nor.

Furthermore, although JP-A-60-64824 describes expanding the parison outside the mold, it is also necessary to control the pressure of the pressurized fluid blown into the inside of the parison inside the closed mold. There is no mention or suggestion regarding this.

In any case, there is no description or suggestion in the above-mentioned publications about controlling the pressure of the pressurized fluid blown into the inside of the parison in the closed mold, and therefore, the techniques described in these publications are In this case, it is assumed that the pressure inside the parison in the closed mold is maintained at the high pressure required for this crimping even after the parison is crimped onto the surface of the cavity, similar to the conventional blow molding machine. However, maintaining the internal pressure of the parison in a closed mold at a high pressure even after the parison is crimped onto the surface of the cavity does not make efficient use of the pressurized fluid, and it is difficult to exhaust the fluid. There are problems such as sometimes accompanied by intense noise.

Therefore, an object of the present invention is to enable efficient use of pressurized fluid by controlling the pressure of the pressurized fluid blown into the inside of a parison in a closed mold, and to
An object of the present invention is to provide a control method for a blow molding machine and a device thereof that can reduce noise during exhaust.

Means for Solving Problem C] The present invention provides a control method for a blow molding machine that holds a parison in a mold and blows pressurized fluid into the inside of the parison to form a hollow product. The above object is achieved by providing a control method for a blow molding machine, which is characterized in that after the pressurized fluid presses the surface of the cavity, the pressure of the pressurized fluid is reduced and then exhausted. It is something.

Furthermore, the present invention provides a device that is used directly to implement the control method for such a blow molding machine, which holds a parison in a mold,
A control device for blow molding that blows pressurized fluid into the inside of the parison through a blow nozzle to mold a hollow product, comprising a plurality of pressure sources each supplying pressurized fluid at a different pressure, and The present invention also provides a control device for a blow molding machine, characterized in that a switching valve is provided between the pressure source and the blow nozzle.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, first, one embodiment of the control method for a blow molding machine of the present invention will be described based on FIGS. 1 to 6.

1 to 6 are perspective views showing the continuous molding process of a hollow product by a blow molding method to which an embodiment of the method of the present invention is applied. For molding, first, as shown in FIG. 1, a molding material is extruded from an extruder 1 into a tube shape to form a parison 2. When the photoelectric switch 3 detects that the parison 2 has reached a certain length, the mold 4 moves (diagonally rises) to a position where the parison 2 is sandwiched, as shown in FIG. As shown, the mold 4 sandwiches the parison, and the hot cutter 5 cuts the parison 2. When the mold 4 holding the cut parison 2 is moved (diagonally lowered) to a position where pressurized fluid, for example pressurized air, is blown into the parison 2 as shown in Fig. 4, it is moved (diagonally downward) to the position shown in Fig. As shown, the blowing nozzle 6 blows and blows pressurized air while descending toward the mold 4 and is driven into the mold 4, and the parison 2 is pressed against the surface of the cavity by the pressurized air and corresponds to the shape of the cavity. Molded into a hollow product. Once the hollow product is formed,
After exhausting to the atmosphere, as shown in Figure 6,
The mold 4 is opened and the hollow articles 7 are discharged in alignment onto the conveyor s by pressurized air discharged from the blow nozzle 6.

In the method of the present invention, after the injection of the injection nozzle 6 into the parison 2 and before exhaustion, the pressure of the pressurized air discharged from the injection nozzle 6 is controlled as follows. That is, after the blow nozzle 6 is driven into the parison 2, first, as shown in the time chart of FIG. 7, the pressurized air discharged from the blow nozzle 6 is
Pressure Po (4~l OKg/cd, e.g. 7Kg/c) required to press parison 2 onto the surface of the cavity
d) into the parison 2 (2 to t3 (2 to 6 seconds, e.g. 4 seconds), the blowing forms the hollow article 7 along the surface of the cavity and cools it. Beforehand, the pressure of the pressurized air is reduced, and the pressure P required to carry out the cooling process while maintaining the shape of the molded hollow article 7 is 2 to 5 Kg/cJ, for example 3
．． 5Kg/cj) in parison 2 (between 3 and L4 (3
Pressurized air is blown for ~10 seconds, e.g. 5°2 seconds) to further cool the hollow article 7. Like this parison 2
By controlling the pressure of pressurized air blown into the
The minimum necessary blowing pressure can always be applied inside the parison 2, which can significantly reduce energy consumption and reduce the pressure of pressurized air released into the atmosphere, reducing noise caused by exhaust air. can be reduced.

Furthermore, in the above embodiment, as shown in FIG.
From the time when the blowing nozzle 6 starts descending until immediately after it is driven into the mold 4 (the blowing nozzle 6 is driven at tl), pressurized air at the pressure PL is used even during 2, and Since the pressurized air at the pressure PL is used even between t6 and t7 when the hollow article 7 is discharged, the pressure of the pressurized air released into the atmosphere is relatively small, and the pressure into the atmosphere is reduced. Pressurized air at the above pressure pH can also be used between to ``'' tz and between t6 and t7, although the noise associated with the air discharge can be lowered.

Next, the control device for the blow molding machine of the present invention is shown in FIGS.
An example shown in FIG. 0 will be described.

8 to 10 are flow diagrams of pressurized air in one embodiment of the apparatus of the present invention, in which FIG. 8 shows the flow when the blowing is stopped, and FIG. 9 shows the flow when the pressurized air at the pressure PL is blown. FIG. 10 shows the state when pressurized air of pressure Pl+ is blown. In these figures, 6 is a blowing nozzle, DCV-H.

DCV-L is a switching valve, SV is a shuttle valve, QEV is a quick exhaust valve, PRV is a pressure reducing valve, SOV is a solenoid valve, and the switching valves DCV-H and DCV-L are air controlled via the solenoid valve SOV. It is an operating valve, and the pressure P is applied to the switching valve DCV-H.
H pressurized air is supplied from the pressure source, and the switching valve DC
Pressurized air at a pressure PL is supplied to V-L from another pressure source which is formed by reducing the pressure from the above pressure source via a pressure reducing valve PRV.

Therefore, when pressurized air at pressure PL is blown, as shown in FIG. 9, the switching valve DCV-L operates and the shuttle valve S
Pressurized air at pressure PL is supplied to the blowing nozzle 6 via V.

In addition, when pressurized air at pressure P is blown, as shown in FIG.
of pressurized air is supplied to the blow nozzle 6.

Further, the apparatus of the above embodiment is controlled by a programmable time relay or the like, and is controlled so as to suitably implement the blow molding machine control method of the present invention as described above.

The above is a summary of the blow molding machine control method and device of the present invention! Although the aspects and one embodiment have been described, in the present invention, a parison refers to a hollow material that is preformed so that it can be sandwiched between molds and into which pressurized fluid can be blown, and is limited to a hollow material that is extruded into a tube shape. It is not something that will be done,
Furthermore, the blow molding machine control method and apparatus of the present invention are not limited to these one embodiment and example; for example, instead of extruding a tube-shaped parison, two sheets are extruded in parallel. It may be applied to various methods such as extrusion and a sheet blowing method in which the extrusion is sandwiched between molds.

In addition, the blow molding machine to be controlled by the blow molding machine control method and device of the present invention includes a cold parison method in which the parison molding and blowing processes are separated, and an injection molding method in which a bottomed parison is made by injection molding. A molding machine using a molding method or the like may also be used.

That is, the blow molding machines to be controlled by the blow molding machine control method and apparatus of the present invention include all molding machines that have a blow molding process.

Furthermore, if the method and apparatus for controlling a blow molding machine of the present invention are combined with the mold clamping force control method described in JP-A-59-176024, energy consumption can be significantly reduced.

The present invention is suitable for molding hollow articles made of synthetic resins such as polyethylene, polypropylene, polyvinyl chloride, and polyethylene terephthalate.

〔Effect of the invention〕

According to the blow molding machine control method and apparatus of the present invention, the pressure of the pressurized fluid blown into the inside of the parison in the closed mold is effectively controlled, so that the pressurized fluid is used efficiently. In addition, it is possible to reduce the noise that accompanies the release of the pressurized fluid from inside the molded parison, which is a tremendous effect.

[Brief explanation of the drawing]

1 to 6 are perspective views illustrating the continuous molding process of a hollow article by a blow molding method using an embodiment of the method of the present invention, and FIG. 7 is a perspective view showing one embodiment of the method of the present invention. A time chart in a blow molding method applying the embodiment,
8 to 10 are flow diagrams of pressurized air in one embodiment of the apparatus of the present invention, in which FIG. 8 shows the flow when the blowing is stopped, and FIG. 9 shows the flow when the pressurized air at the pressure PL is blown. Figure 1O shows the state when pressurized air of pressure P is blown. 2...Parison 4...Mold 6...Blowing nozzle DCV-H, DCV-L-・-Switching valve Fig. 3 Fig. 4 Fig. 5 Fig. 6

Claims (2)

[Claims] (1) A control method for a blow molding machine in which a parison is held in a mold and a pressurized fluid is blown into the inside of the parison to form a hollow product, wherein the parison is pressed against the surface of a cavity by the pressurized fluid. A method for controlling a blow molding machine, comprising: reducing the pressure of the pressurized fluid, and then exhausting the pressurized fluid. (2) In a control device for a blow molding machine that holds a parison in a mold and blows pressurized fluid into the inside of the parison through a blow nozzle to form a hollow product, pressurized fluids of different pressures are supplied to each blow molding machine. A control device for a blow molding machine, comprising a plurality of pressure sources for controlling the blow molding machine, and a switching valve between each of the pressure sources and the blow nozzle.