JPH0355222A - Blow molding method and device, and blow air-cleaning device - Google Patents

Abstract

PURPOSE:To improve the efficiency of the blowing of blow air and the cooling of a molded object by a method in which after the blowing into of blow air, the air-blowing of blow nozzles is stopped partially, and the air in the molded object is extracted, and then the molded object is cooled. CONSTITUTION:A mold 10 is the type in which a blow pin is stuck from the side of a parison and air is blown into. Blown air is introduced in the parison M from an air compressor 50 through ducts 52, 53 by using the blow pins 20, 25 at two position up and down and an intermediate blow pin 21 according to necessity, whereby the parison is shaped into a prescribed cavity shape. After the blown air has been sent for a prescribed time, a second exchanging valve is operated, whereby while the air-blowing by the blow pin 25 is stopped, it is switched to exhaust side. Next, the air blown into a molded object M from the blow pins 20, 21 is extracted from the blow pin 25, and the inner side of the molded object is cooled for a prescribed time. Consequently, the cooling of the inside of the molded object may be carried out effectively with good efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to blow molding of plastics, and in particular to a method for effectively and efficiently blowing blow air and cooling a molded product after blowing. The present invention also relates to a blow molding method and apparatus for performing blow molding while purifying the decomposed gas of plastic mixed in the exhaust air after blow molding, and a blow air cleaning apparatus. (Prior art) In the extrusion blow molding of plastics, an extruded parison is clamped in a mold, and air is blown into the clamped parison to expand the parison and shape it into a predetermined cavity shape. In addition to cooling the molded product from the outside, there is also a method of cooling the molded product from within by feeding air into the molded product and extracting the warmed air. Generally, as shown in FIG. 7, the method is as follows: two air channels 72.
73 was installed, air was blown in from one side, and warmed air was exhausted from the other side. This is because air blow holes are inevitably formed in the molded product in the blow molded product, so it is necessary to minimize the number of holes as much as possible. However, in this method, two air flow paths must be provided in the nozzle, which complicates the structure of the blow nozzle, and blows and exhausts air in very close positions, which may depend on the shape of the molded product. There was a risk that either the circulation of blown air or uneven internal cooling would be insufficient. Furthermore, in the case of a hollow boiler 80 shown in FIG. 8, in which most of the surface is a visible part and only the mounting part 8l is an invisible part, the blowing is carried out from the mounting part, which is an invisible part. However, as shown in the figure, the attachment part 8l is on the side surface facing the longitudinal force of the product, and it is difficult to blow from the extrusion tie as described above. will be held. Additionally, for large products such as this spoiler, multiple blow nozzles are usually used to shorten the blowing time. This so-called horizontal blowing method includes
As shown in FIG. 9, a thin, needle-shaped solo nozzle 90 is usually used, and the nozzle 90 is pierced into the holy side of the parison 91 to perform the blowing. At this time, it was considered to provide the nozzle with holes for blowing and exhaust as described above, but since air would not blow out from the exhaust hole when piercing the wall of the parison, the hole would be clogged with resin. There is almost no use for exhaust air. Therefore, the reality is that no exhaust hole or flow path is provided in such side blow nozzles. For this reason, conventional cooling of hollow molded products has mostly been done by cooling the outer surface using the mold, which is very expensive. ! ! ! The longer the molded product is, the longer it takes to cool it, creating a longer molding cycle.

By the way, the parison (usually cylindrical) extruded from the extruder is in a molten state, and some of the various additives such as plastic decomposition gas and jqq agents are volatilized from its surface in gaseous form. are doing. Of this gas, the gas that volatilizes from the outside of the parison is sucked into the duct installed at the top of the extruder, but the gas inside the barring is trapped inside the molded product and is released together with the exhaust of blow air when the molded product is taken out. It is often emitted and contributes to the deterioration of the working environment. Furthermore, even if a flow nozzle provided with an exhaust passage is used as described above, the solenoid valve of the exhaust passage is closed during blowing to maintain the pressure of the blown air. After shaping, the valve is opened and the blown air is discharged.

However, many of the gaseous substances mentioned above become tar-like when cooled, and when exhausted, the 're provided in the exhaust flow path
It often accumulates on the solenoid valve, causing the solenoid valve to stop working. As shown in the example shown in FIG. 7, in an air circuit having such an m-magnetic valve 74, a mist of low-viscosity oil is mixed into the air by an oiler 75 to control the operation of the 1-magnetic valve 74. There is a known method to ensure this, but when such air is used for blowing, oil often adheres to the inner surface of the molded product and has an adverse effect on the molded product. It is not used in blow molding in recent years. (Invention or Solution Section WU) Therefore, the present invention aims to provide a new blow molding method that solves the problems of the prior art described above, and in particular, uses a plurality of blow molding nozzles. In blow molding, we propose a method for effectively and efficiently blowing blow air and cooling the molded product after blowing, and a blow molding method and device for blow molding while purifying decomposed gas, etc. in the exhaust gas. .

(Means for Solving the Problems) This first invention provides that when blow molding is performed by blowing air into a parison using a plurality of blow nozzles, after the blow air is blown by the blow nozzles, some of the blow nozzles are The present invention relates to a blow molding method characterized in that the blowing of air in a nozzle is stopped, and the air inside the molded product is extracted from the stopped blow nozzle to cool the molded product.

Further, in the second invention, when performing blow molding by blowing air into the parison using a plurality of blow nozzles, after blowing air from the blow nozzles, blowing of air is stopped from some of the blow nozzles. The present invention relates to a blow molding method characterized in that the air in the molded product is extracted from the stopped blow nozzle, and the extracted air is exploded and exhausted through an air cleaner device.

Further, a third invention provides an air cleaner and a switching valve between at least one of the blow nozzles connected to the air source and the air source when blow molding is performed by blowing air into the parison using a plurality of blow nozzles. At the time of initial air blowing, all the blow nozzles are used to blow air to shape the parison into a predetermined shape, and then the air blowing from the blow nozzles connected to the air cleaner device is stopped, and the air is blown from the stopped blow nozzles. This relates to a blow molding method characterized by extracting air from a molded product, purifying the air through an air cleaner device, and exhausting the air from a switching valve. In addition, in a device that blows air into a parison using a plurality of blow nozzles to form a blow shape, the fourth blower 1l is configured such that some of the plurality of blow nozzles connected to the air source can pass in both directions. The present invention relates to a blow molding apparatus characterized in that the blow molding apparatus is configured to be able to freely switch between feeding in air and extracting air through an air cleaner section. In a fifth aspect of the present invention, there is provided a partition plate which divides the inside of the container into two chambers by having a lower end reaching below the water surface of the tree in an airtight container in which water is stored, and which is provided vertically from the upper bottom surface of the container. The present invention relates to a true air cleaning device in which air inlets and outlets are formed in the upper part of the bisected chamber, and air entering from one of the inlets and outlets passes through water and can flow to the other inlet and outlet.

(Operation) According to the blow molding method of the present invention, first, a plurality of blow pins or parisons are pierced as usual, and air is blown into the parison from the blow pins to perform blow molding. During cooling after the parison has been expanded and shaped into a predetermined shape, air blowing is stopped in some of the blowbins. Then, through the stopped blow pin, the air blown into the molded product from another blow pin is extracted and used for internal cooling of the molded product. The molded product can be efficiently and effectively cooled in a short time by external cooling that accompanies cooling of the mold and internal cooling that accompanies the extraction of this internal air. At this time, since the blowing and exhausting are performed using an air cleaner device in one blow nozzle, the exhausted air is purified and discharged. Since the gas content in the exhaust is removed at this time, the switching valve will not become inoperable due to tar content such as cracked gas. Further, in the blow molding of the present invention, some of the blow pins of the plurality of blow pins connected to the air source are configured such that air can be sent in or air can be taken out through an air cleaner section that can be passed in both directions. It is configured so that it can be switched freely. Therefore, the desired operation can be achieved simply by switching the air, without using special blow pins or nozzles, and without requiring special piping for cleaning exhaust air. (Example) The details of this invention will be explained below according to the attached drawings.
FIG. 1 is a schematic diagram showing the blow molding state of a molding apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the internal cooling state of the molding apparatus. 3 is a longitudinal cross-sectional view showing an example of an air cleaner device, FIG. 4 is a vertical cross-sectional view of the same device with the cutting position changed to 90 degrees, and FIG. 5 is a vertical cross-sectional view showing an example of air cleaner device. A cross-sectional view showing the state, FIG. M8, is a cross-sectional view showing a state in which air is introduced from the other side.

In the examples shown in FIGS. 1 and 2, reference numeral 10 is a blow molding die, l1 is a cavity thereof, and M is a shaped parison (molded product). 20, 21.25 are blow bins, 30 is an air cleaning device, 50 is an air compressor (air source), 5l is its pressure gauge, 52, 53, 54.55 are air conduits, and 60.65 is a switching valve, respectively.

The mold 10 is a known blow molding mold for shaping hollow parts such as air boilers for automobiles, and is a so-called horizontal blow molding mold in which a blow pin (blow nozzle) is inserted from the side of the parison and air is blown into the mold. be. As shown in FIG. 1, in the embodiment, upper and lower blow pins 20, 25, and if necessary, an intermediate blow pin 2l are used to connect the air conduit 50 to the conduit 52.53.5.
Blow air is introduced into the parison M through the parison M and shaped into a predetermined cavity shape. At this time, the first switching valve 6
0 and the second switching valve 65 are turned on to the air feed side as shown in the figure. After the blowing air has been fed for a predetermined period of time (for example, 50 seconds), the second switching valve is operated as shown in FIG. 2, and only the blowing of air from the blowing pin 25 of the blowing pins 20, 21 and 25 is stopped. Then, the air blown into the molded product M from the blow pins 20 and 21 is extracted from the tube 25, and the inner surface of the molded product is cooled for a predetermined period of time (for example, 50 seconds). At this time, it goes without saying that the mold is also cooled and the molded product is also cooled from the outside.After cooling is completed, the first
The switching valve is switched, the blowing of air from the blow pins 20, 21 is stopped, the mold 1O is opened, and the molded product M is taken out and the next process** is carried out.

By the way, in this type of blow molding, the air after cooling the inside of the molded product is mixed with decomposed gas during molding, gases such as plasticizers and additives, oil, and various impurities, and if left in this state, Not only does this hinder the operation of the switching valve, but it is also unfavorable from the factory environment. Therefore,
It becomes necessary to clean the extracted air after cooling. As already explained, in this invention, the blow pin 2
Only air is blown in and extracted through the circuit 5, and air can pass in both directions in this circuit.

Therefore, an air cleaner section 30 is interposed in the air circuit of the blowbin 25, which can be used in both directions.

An example of a part of this two-way air cleaner is shown in the drawings below in Figure 3. In other words, air cleaner system I! 30
As can be understood from the cross-sectional views of FIGS. 3 and 4, the lower end 32A reaches below the water surface of the water W in the closed container 3l containing the water W, so that two The partition plate 32 that divides into two parts 41 and 42 is the upper bottom surface 3J. It is vertically installed from A, and air inlets and outlets 45 and 46 are formed in the upper part of the chamber divided into two parts. In the figure, reference numeral 31B is the lower bottom plate of the container, and 34 is a water shielding plate for preventing water droplets splashing from the water surface from entering the air inlet/outlet 45.46.
35 is the water supply and drainage port. An air cleaner with the above structure? In the case of ti30, for example, when air is injected from the aero 45 (as shown in Fig. 5, the chamber 4
It pushes down the water surface Wl of the tree W in 1, enters the water on the other chamber 42 side from the bottom of the partition plate 32, and is sent out from the water surface W2 through the other chamber 42 from the aero 46. Gas, oil, and other impurities are washed away from the air in water, and the air is sent out as clean air.

The case where the air is injected from Aero 46 is exactly the same as above as shown in the 6th pig. The air injected into the chamber 42 pushes down the water surface W2, enters the water from the lower end of the partition plate 32 to the other chamber 41 side, and lowers the water surface W2.
It is then sent out from Aero 45 via another channel 41.

In this manner, with this device, air cleaning can be performed in both directions using the air's own pressure without requiring any special switching mechanism.

In the above description, an example in which two blow pins are mainly used and an air cleaning device is provided in one of the air conduits has been described, but it goes without saying that three or more blow pins may be provided.

Also, in that case, the air cleaning device is placed in an appropriate conduit, taking into account cooling through air circulation. For example, when three blow pins are disposed above and below, an air cleaning device may be disposed in a conduit connected to an intermediate blow bin.

(Effects) As illustrated and explained above, according to the present invention, air blown into the molded product from other blow pins is extracted from the other blow pins through the blow pin whose air blowing has been stopped, and the molded product is molded. Since the product is internally cooled, it is possible to efficiently and effectively cool the product internally without requiring a special nozzle device or circuit with a conventional al4I1. It became so.

Further, according to the present invention, the decomposed gas and the like mixed in the blow air are purified and exhausted, so that the working environment can be improved.

In particular, the present invention is extremely useful when blowing air using a plurality of blow pins, which is called a so-called needle blower.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the blow molding state of a molding device according to an embodiment of the present invention, Fig. 2 is a schematic diagram showing the internal cooling state thereof, and Fig. 3 is a longitudinal section showing an example of an air cleaner device. Figure 4 is a longitudinal cross-sectional view of the turning device with the cutting position changed by 90 degrees, Figure 5 is a cross-sectional view showing the state where air is flowing in from one side of the device, and Figure 6 is the same from the other side. 7 is a schematic diagram showing an example of a conventional blow molding method, FIG. 8 is a cutaway sectional view showing an example of a blow molded product, and FIG. 9 is a diagram showing the molded state. This is a cross-sectional view. 10...Blow molding mold. 11...Cavity, 20
, 21.25... Blow pin, 30... Air cleaning device, 32... Partition plate, 41.42... Chamber. 50... Air compressor 1 nossa (air source). 60.85...Switching valve, M...
・Parison (molded product), W...water. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. When performing blow molding by blowing air into the parison using a plurality of blow nozzles, after blowing air from the blow nozzles, some of the blow nozzles stop blowing air. A blow molding method characterized in that air in the molded product is extracted from the stopped blow nozzle to cool the molded product. 2. When performing blow molding by blowing air into the parison using a plurality of blow nozzles, after blowing air from the blow nozzles, some of the blow nozzles stop blowing air, and the stopped blow nozzles A blow molding method characterized in that the air inside the molded product is extracted, and the extracted air is purified and exhausted through an air cleaner device. 3. When performing blow molding by blowing air into the parison using a plurality of blow nozzles, interposing an air cleaner and a switching valve between at least one of the blow nozzles connected to the air source and the air source; At the time of initial air blowing, the parison is shaped into a predetermined shape by blowing air through all the blow nozzles, and then the blowing of air by the blow nozzles connected to the air cleaner device is stopped, and the air inside the molded product is A blow molding method characterized by extracting air, purifying the air through an air cleaner device, and exhausting the air from a switching valve. 4. In a device that performs blow molding by blowing air into a parison using a plurality of blow nozzles, some of the plurality of blow nozzles connected to an air source blow air through an air cleaner section that can freely flow in both directions. A blow molding device characterized in that it is configured to be switchable so that air can be fed in or air can be extracted. 5. A partition plate that divides the inside of the container into two chambers by having a lower end reaching below the surface of the water in a closed container containing water is provided vertically from the upper bottom surface, and the divided chamber is divided into two chambers. A blow air cleaning device in which air inlets and outlets are formed in the upper part, and air that enters from one of the inlets passes through water and can flow to the other inlet and outlet.