JP2767762B2 - Blow molding method and apparatus and blow air cleaning apparatus - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to blow molding of plastics, and more particularly to a method for effectively and efficiently blowing blow air and cooling a molded product after the blow.
The present invention also relates to a blow molding method and apparatus for purifying decomposed gas and the like of plastic mixed into blow-molded exhaust air, and a blow-air cleaning apparatus.

(Prior Art) In extrusion blow molding of plastics, when an extruded parison is clamped by a mold, air is blown into the clamped parison to expand the parison and form the parison into a predetermined cavity shape. In addition to cooling from the outside by the mold,
There is a method in which air is further sent into a molded product, and warmed air is extracted to cool the molded product from the inside. Generally, as shown in FIG. 7, a blow nozzle 71 provided at the tip of the extrusion die of the parison has two air flow paths 72 and 73.
In general, air is blown from one side and warmed air is exhausted from the other side. This is because, in blow molding, a blow hole for air is inevitably formed in a molded product, and it is necessary to reduce the hole as much as possible.

However, in this method, two air flow paths must be provided in the nozzle, and the structure of the blow nozzle becomes complicated, and the blowing and exhausting are performed at extremely close positions. In some cases, the circulation of the blown air was uneven and the internal cooling was insufficient. For example, in the case where most of the surface is a visible part and only the mounting part 81 is an invisible part, such as a hollow spoiler 80 shown in FIG. 8, blowing is performed from the mounting part which is a non-visible part. Although it is necessary to perform this, as shown in the figure, the mounting portion 81 is a longitudinal side surface of the product, and it is difficult to blow from the extrusion die as described above, and instead, it is necessary to perform blowing from the side of the parison, commonly called side blowing. Done.

In the case of a large product such as a spoiler, a plurality of blow nozzles are usually used in order to reduce the blowing time. As shown in FIG. 9, a thin blow nozzle 90 having a needle-like shape is generally used in the method called horizontal blowing, and blowing is performed by piercing the nozzle 90 into the wall surface of the parison 91. At this time, it was conceived to provide the above-mentioned nozzles for blowing and exhausting the nozzles.However, when piercing the wall of the parison, air does not blow out from the exhausting holes, so that resin was clogged in the holes. It makes little use of exhaust. Therefore, it is a fact that such a side blow blow nozzle is not provided with an exhaust hole and a flow path.

For this reason, cooling of a hollow molded product in the related art is mostly performed by cooling the outer surface using a mold, and the larger the molded product, the longer the cooling time and the longer the molding cycle.

By the way, the parison (usually cylindrical) extruded from the extruder is in a molten state, and a part of various additives such as a decomposition gas of plastic and a plasticizer is gasified and volatilized from the surface. ing. Among these gases, the gas volatilizing from the outer surface of the parison is sucked into the duct provided at the upper part of the extruder, but the gas in the parison is confined in the molded product and is discharged together with the blow air exhaust when removing the molded product. Often, this is a factor that impairs the work environment. Even if the blow nozzle is provided with an exhaust passage as described above, the solenoid valve of the exhaust passage is closed to maintain the pressure of the blown air during blowing. Then, after shaping, the valve is opened to discharge the blown air.

However, the above-mentioned gaseous components often become tar-like when cooled, and often adhere to and accumulate on an electromagnetic valve provided in an exhaust passage at the time of exhaustion, so that the electromagnetic valve often fails to operate. In an air circuit having such a solenoid valve 74, as in the example shown in FIG. 7, low-viscosity oil is mixed into the air by an oiler 75 in the form of a mist to ensure the operation of the solenoid valve 74. Is known, but when such air is used for blow molding,
Since oil often adheres to the inner surface of a molded product and adversely affects the molded product, it is not used in recent blow molding except for special cases.

(Problems to be Solved by the Invention) Accordingly, the present invention is to provide a novel blow molding method which solves the problems of the above-mentioned conventional technology, and in particular, forms the molding using a plurality of blow nozzles. The present invention proposes a method for effectively and efficiently blowing blow air and cooling a molded product after the blow, and a blow molding method and apparatus for purifying decomposed gas and the like in exhaust gas.

(Means for Solving the Problems) According to the first invention, when air is blown into a parison by a plurality of blow nozzles to perform blow molding, a part of the blow nozzles is blown after blowing the blow air by the blow nozzles. The present invention relates to a blow molding method, characterized in that air in a molded product is blown out from the stopped blow nozzle in which the blowing of air is stopped at the nozzle to cool the molded product.

Further, in the second invention, when air is blown into the parison by a plurality of blow nozzles to perform blow molding, after blowing the blow air by the blow nozzles, the blow of air is stopped at some of the blow nozzles. The present invention relates to a blow molding method, wherein air in a molded product is extracted from the stopped blow nozzle, and the extracted air is purified and exhausted through an air cleaner device.

According to a third aspect of the present invention, when air is blown into the parison by a plurality of blow nozzles to perform blow molding, the air cleaner is switched between at least one of the blow nozzles connected to the air source and the air source. A valve is interposed, and at the time of initial air blowing, the parison is shaped into a predetermined shape by blowing air with all the blow nozzles, and then the blowing of air by the blow nozzle connected to the air cleaner device is stopped, and the stopped blow nozzle is stopped. The present invention also relates to a blow molding method characterized in that air in a molded product is further extracted, air is purified through an air cleaner device, and exhausted from a switching valve.

According to a fourth aspect of the present invention, there is provided an apparatus for performing blow molding by blowing air into a parison by a plurality of blow nozzles, wherein an air cleaner in which some of the plurality of blow nozzles connected to an air source are both free to pass. The present invention relates to a blow molding apparatus characterized in that it is configured to be switchable so that air can be sent or air can be extracted through a section.

According to a fifth aspect of the present invention, a partition plate that divides the inside of the container into two chambers by hanging the lower end below the surface of the water in a closed container containing water is vertically provided from an upper bottom surface, The present invention relates to a blow-air cleaning device in which air inlets and outlets are formed at the upper portions of the two divided chambers, and air that enters from one of the inlets and outlets can flow through water and flow to the other.

(Operation) According to the blow molding method of the present invention, first, a plurality of blow pins are pierced into the parison as usual, and air is blown into the parison from the blow pins to perform blow molding. During cooling after the parison expands and is shaped into a predetermined shape, the blowing of air is stopped at some of the blow pins. Then, through the stopped blow pins, the air blown into the molded product from another blow pin is extracted to cool the interior of the molded product. The molded article can be efficiently and effectively cooled in a short time by the external cooling accompanying the cooling of the mold and the internal cooling accompanying the extraction of the internal air.

At this time, since air is blown into and exhausted from one blow nozzle through an air cleaner device, the exhausted air is purified and discharged. At this time, since the gas component in the exhaust gas is removed, the switching valve does not stop operating due to the tar component such as the decomposition gas.

Further, in the blow molding of the present invention, some of the plurality of blow pins connected to the air source are capable of sending air or extracting air through an air cleaner portion that can pass through both. It is configured to be switchable. Therefore, the desired operation can be achieved only by switching the air without using a special blow pin or nozzle and without requiring a special pipe for cleaning the discharged air.

(Embodiment) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a blow molding state of a molding apparatus showing one embodiment of the present invention, and FIG. FIG. 3 is a longitudinal sectional view showing an example of an air cleaner device, FIG. 4 is a longitudinal sectional view of the same device in which a cutting position is changed by 90 degrees, and FIG. 5 is a diagram showing air from one side of the device. FIG. 6 is a cross-sectional view showing a state where air has flowed in, and FIG. 6 is a cross-sectional view showing a state where air has flowed in from the other side.

In the examples of FIGS. 1 and 2, reference numeral 10 denotes a blow mold, 11 denotes a cavity thereof, M denotes a formed parison (molded product), 20, 21, 25 blow pins, 30 denotes an air cleaning device, 50 Represents an air compressor (air source), 51 represents its pressure gauge, 52, 53, 54, and 55 represent air conduits, and 60 and 65 represent switching valves.

The molded product 10 is, for example, a known blow molding die for molding a hollow component such as an air spoiler for a vehicle, and is a so-called horizontal blow type in which a blow pin (blowing nozzle) is pierced from the side of the parison to blow air. .

As shown in FIG. 1, in the embodiment, blow air is introduced into the parison M from the air compressor 50 via conduits 52, 53, 55 by using two upper and lower blow pins 20, 25 and an intermediate blow pin 21 as necessary. It is introduced and shaped into a predetermined cavity shape. At this time, the first switching valve 60 and the second switching valve 65 are turned on to the air feeding side as shown in the figure.

After the blowing air is supplied for a predetermined time (for example, 50 seconds), as shown in FIG. 2, the second switching valve is operated, and the blowing of air from the blow pins 25 of the blow pins 20, 21, and 25 is stopped. Is switched to the exhaust side. Then, the air blown into the molded article M from the blow pins 20 and 21 is extracted from the blow pins 25, and is taken out for a predetermined time (for example,
The inner surface of the molded product is cooled for 50 seconds. At this time, needless to say, the mold also cools the cooled molded article from outside.

After cooling is completed, the first switching valve is switched and the blow pin
The blowing of the air from 20, 21 is stopped, the mold 10 is opened, and the molded article M is taken out and the next step is prepared.

By the way, in this type of blow molding, the air after cooling the inside of the molded product is mixed with a gas such as a decomposition gas or a plasticizer or an additive during molding, an oil component, or various impurities. This not only hinders the operation of the switching valve, but is also undesirable from the factory environment. Therefore, it is necessary to clean the extracted air after cooling.

As described above, in the present invention, the blow pin 25
The air is blown in and out through the circuit, and both sides of the air pass through this circuit. Accordingly, the air circuit of the blow pin 25 is provided with the air cleaner 30 which can pass through both sides.

An example of this two-way free air cleaner section is shown in FIGS. That is, the air cleaner device 30
As can be understood from the cross-sectional views of FIGS. 3 and 4, the lower end 32A reaches below the surface of the water W in the closed container 31 in which the water W is stored, so that the inside of the container is A partition plate 32 that divides into two chambers 41 and 42 is suspended from the upper bottom surface 31A, and air inlets and outlets 45 and 46 are formed in the upper part of the two divided chambers.
In the drawing, reference numeral 31B denotes a lower bottom plate of the container, 34 denotes a water shield plate for preventing water droplets repelling from the water surface from entering the air inlets and outlets 45 and 46, and 35 denotes a water supply / drain port.

In the air cleaner device 30 having the above configuration,
For example, when air is injected from the air port 45, as shown in FIG. 5, the water surface W1 of the water W in the chamber 41 is pushed down to enter the water on the other chamber 42 side from the lower end of the partition plate 32, Air port 46 through other chamber 42 from water surface W2
Will be sent out. The air is cleaned as gas, oil, or various impurities, and is sent out as clean air.

The case where air is injected from the air port 46 is exactly the same as above as shown in FIG. The air injected into the chamber 42 pushes down the water surface W2, enters the water on the other chamber 41 side from the lower end of the partition plate 32, and is sent from the air surface 45 through the other chamber 41 from the water surface W1.

As described above, according to this apparatus, no special switching mechanism is required, and air cleaning can be carried out in both directions freely by the pressure of the air itself.

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

Further, in that case, the air cleaning device is disposed on an appropriate conduit in consideration of cooling by air circulation. For example, when three blow pins are arranged above and below, an air cleaning device is arranged in a conduit leading to an intermediate blow pin.

(Effects) As shown and described above, according to the present invention, the air blown into the molded product from another blow pin is blown out of the plurality of blow pins through the blow pin of which the air blowing is stopped, and the molded product is formed. Since the internal cooling of the molded article is performed, the internal cooling of the molded article can be performed efficiently and effectively without the need for a nozzle device or a circuit having a special mechanism as in the related art. became.

Further, according to the present invention, since the decomposition gas and the like mixed in the blow air is purified and exhausted, the working environment can be improved.

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

[Brief description of the drawings]

FIG. 1 is a schematic view showing a blow molding state of a molding apparatus showing one embodiment of the present invention, FIG. 2 is a schematic view showing the same internal cooling state, and FIG. 3 is a longitudinal section showing an example of an air cleaner apparatus. Fig. 4, Fig. 4 is a longitudinal sectional view of the same device in which the cutting position is different by 90 degrees, Fig. 5 is a sectional view showing a state where air flows in from one side of the device, and Fig. FIG. 7 is a schematic view 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 sectional view showing the molded state. It is sectional drawing. 10: Blow mold, 11: Cavity, 20, 21, 25 ... Blow pin, 30: Air cleaning device, 32: Partition plate, 41, 4
2 ... chamber, 50 ... air compressor (air source), 60,
65: switching valve, M: parison (molded product), W: water.

Claims (5)

(57) [Claims] When blowing air into a parison by a plurality of blow nozzles to perform blow molding, after blowing blow air by the blow nozzles, the blow of air is stopped at some of the blow nozzles and the stop is performed. A blow molding method, characterized in that air in a molded product is extracted from a blow nozzle thus formed to cool the molded product. 2. When blowing air into a parison by a plurality of blow nozzles to perform blow molding, after blowing blow air by the blow nozzles, the blow of air is stopped at some of the blow nozzles and the stop is performed. Blow-out method, characterized in that air in the molded product is extracted from the blow nozzle, and the extracted air is purified and exhausted through an air cleaner device. 3. When air is blown into a parison by a plurality of blow nozzles to perform blow molding, an air cleaner and a switching valve are provided between at least one of the blow nozzles connected to an air source and the air source. At the time of initial air blowing, the parison is shaped into a predetermined shape by blowing air with all the blow nozzles, and then the blowing of air by the blow nozzle connected to the air cleaner device is stopped, and molding is performed from the stopped blow nozzle. A blow molding method, wherein air inside the product is extracted, the air is purified through an air cleaner device and exhausted from a switching valve. 4. An apparatus in which air is blown into a parison by a plurality of blow nozzles to perform blow molding, wherein an air cleaner portion in which some of the plurality of blow nozzles connected to an air source are freely traversable. A blow molding apparatus characterized in that the blow molding apparatus is configured to be switchable so that air can be supplied or air can be extracted through the apparatus. 5. A partition plate which divides the inside of the container into two chambers when the lower end reaches below the surface of the water in a closed container containing water is vertically provided from an upper bottom surface. An air inlet / outlet is formed in the upper portion of the chamber, and air entering from one of the inlets / outlets can flow through water and flow to the other inlet / outlet.