JPS5914330B2 - Method and device for confirming completion of cooling in foam molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and device for confirming the completion of cooling in foam molding, which enables accurate mold release timing by easily confirming the timing of completion of cooling, thereby shortening the molding cycle and preventing molding defects. We are trying to reduce the rate.

In conventional foam molding, in most cases a timer was used to determine the completion of the cooling process using a molding machine.

In addition, some block molding machines were actually using Pluton tube type pressure measuring devices. However, when the cooling time was set with a timer, the cooling time set at 30 could not be said to be the optimal time due to fluctuations in the temperature of the cooling water, differences in the foaming power of the raw materials, fluctuations in the foaming ratio, etc. In other words, because it is not possible to automatically confirm the completion of the cooling process, if the cooling time set by the timer is too short, product defects will occur due to insufficient cooling of the molded product, and conversely, if the cooling time set is too long. 35 Although the molded product is sufficiently cooled, the molding cycle becomes longer due to unnecessary cooling water.
Moreover, this excessive cooling causes a drop in the temperature of the mold, which has the disadvantage of requiring extra heating steam when heating the mold in the next process.

In addition, the Pluton tube type pressure measuring device cannot be used for general molding because the pressure receiving part facing the molded product is too large. Therefore, it has been desired to automatically confirm the completion of cooling using a simple and inexpensive method. Therefore, in this invention, we have developed a method for confirming the completion of cooling that satisfies the above requirements. In this method, foam molding is performed by filling a raw material with a heating medium such as steam and expanding the raw material by heating and expanding it with a heating medium such as steam. Completion of cooling of the molded body is automatically confirmed by sensing the pressure while converting the received pressure fluctuation into pressure fluctuation of compressed air.

Next, embodiments of the method of the present invention will be illustrated below with reference to the drawings together with the inventive apparatus used for carrying out the method.

FIG. 1 shows an outline of the device, in which a pair of molds 10
, 20 have one core mold and the other cavity mold, and the molds 10 and 20 have respective steam chambers 11 and 21,
A mold cavity 30 is formed between the molds 10 and 20 and can be filled with a raw material made of expandable thermoplastic resin particles, and steam holes 12 and 22 are provided in the wall on the mold cavity 30 side.

In addition, steam piping 13, 23, cooling water piping 14, 24,
Drain pipes 15, 25, raw material filler 40 and packing 4
5 Furthermore, an eject structure (not shown) and the like are provided in the same manner as in conventional molding equipment. The main components of the present invention include a nozzle part 50 introduced into a part of the mold 10, 20 with a recess 58, an air pressure regulator 60 attached thereto, and an air flow rate regulating valve 70. , a pressure switch 80, a pressure gauge 90, and piping 100 connecting these devices.

In particular, FIG. 2 (FIG. 3) shows a preferred structure for the nozzle portion 50 described above, and FIG. 4 shows a state in which the mold is attached to the mold wall 26 (in some cases to the mold wall 16). That is, in the nozzle part 50, 51 is a nozzle component, 52 is a pressure receiving plate provided on the side facing the mold cavity 30, and 53 is an air introduction pipe connected to the nozzle component 51 on the side opposite to the pressure receiving plate 52. , 54 and 55 are air inlet paths provided in the pressure receiving plate 52, through which air from the air inlet pipe 53 is passed. 56 is a nozzle component 51 and a pressure receiving plate 5
An air passage formed between the two, one of which is connected to the above-mentioned inlet passage 55.
The other side is open to the steam chamber 21 through a ventilation hole 57 that serves as a pressure reduction path.

These air passages are configured as nozzles. The pressure receiving plate 52 closes the air passage 56 with the nozzle component 51 when the foaming pressure of the molded object A in the mold cavity 30 is high, and the foaming pressure fluctuates with cooling and becomes low. In some cases, the air passage 56 is opened and the air passage 56 is movably provided so as to pass through the ventilation hole 57 of the pressure reduction route. However, the pressure receiving plate 52 is formed in such a shape that it cannot be removed from the nozzle component 51 in any direction. Further, the air introduction pipe 53 is connected to a pressure sensing section for detecting fluctuations in the pressure air, and the pressure sensing sections include the already mentioned air pressure regulator 60, air flow rate adjustment valve 70, pressure switch 80, and pressure gauge 90. It consists of piping 100 that connects. In operation using the above device, compressed air is introduced from the air introduction pipe 53.

At that time, the air pressure flow rate is controlled by an air pressure regulator 60 and an air flow rate adjustment valve 70. The introduced air operates in a direction in which the pressure receiving plate 52 closes the air passage 56 between the nozzle component 51 and the foaming pressure of the molded article A in the mold cavity 30 is too high to release it from the mold. However, the air flow has stopped and the air inlet channels 54 and 55 maintain a constant air pressure, but the foaming pressure of the molded article A after heating and expansion decreases and fluctuates as cooling progresses. When this occurs, the pressure receiving plate 52 of the nozzle portion 50 recognizes this as a fluctuation in the receiving pressure and can move in the direction of the molded body A with air pressure, opening the air passage 56. The compressed air thus flows out from the air passage 56 to the steam chamber 21 through the ventilation hole 57 which serves as a path for reducing pressure.
That is, air flows out due to fluctuations in the received pressure, and the pressure in the air sending paths 54 and 55 is gradually reduced, and the pressure drop is indicated to the pressure gauge 90 on the piping 100 side to sense the pressure, and the pressure switch 80 is activated. It activates and moves on to the next mold release process. In this way, fluctuations in the foaming pressure that occur as the molded body A cools are received by the pressure receiving plate 52, and are treated as fluctuations in the received pressure, and the fluctuations in the received pressure are converted into pressure fluctuations of the compressed air while sensing the pressure. It is possible to know when cooling of the molded body A has been completed.

In this way, the foaming pressure of the molded body A is applied to the molded body A into the molds 10 and 2.
It is possible to automatically detect and confirm the point in time when the temperature has decreased from 0 to a level where mold release is possible, and the molds 10 and 20 can be quickly opened to take out the molded product. In addition, the pressure receiving area of the molded body A on the pressure receiving plate 52 which becomes the nozzle part 50 shown in the drawing is 3.
．． 14 (1-J model V1), the recess 58 for the nozzle in the mold had a diameter of 25 mm, and the movable distance of the pressure receiving plate 52 was 0.5 m77!.

Next, to describe an example of implementation using the illustrated apparatus, foamed polystyrene resin was molded in the following procedure.

First, the pre-expanded polystyrene grains used as the raw material have a magnification of 50 times, and the pre-expanded grains are introduced into the mold cavity 30 using the raw material filler 40, and then steam is introduced from the steam pipe 100, 0.8kg/CT! The mixture was heated for 40 seconds at a pressure of i. Cooling water was then sprayed onto the mold from the cooling water introduction pipes 14 and 24 to cool the mold. The air pressure was regulated to 0.91<9/min by the pressure regulator 60, and the flow rate was adjusted by the air flow rate regulating valve 70 to flow the air at 0.51/min. Air was constantly flowing, but when steam heating started,
The pressure gradually increases and reaches 0.9k9/CT at the end of heating.
! It was i. After the raw material is heated and expanded, it progresses to cooling and receives the fluctuations in foaming pressure using the method of this invention. The mold was automatically released by converting the air pressure into an electric signal by the operation of the switch 80.The molded product taken out by the release was a high-quality product, and its thickness was 40 mm.
m77! It was hot. The pressure indicated by the pressure gauge 90 is 0
．． 4k9/Cr! The foaming pressure of the molded product was measured with a foaming pressure measuring device (strain gauge type pressure gauge O) at the time when the molded product reached i, and the foaming pressure of the molded product was 0.3 kg/CTII. In this way, even if the temperature and amount of cooling water change, or even if raw materials with different foaming ratios are used, the completion of cooling can be easily detected and confirmed from the foaming pressure, and the process can be carried out in the most efficient manner. Perform foam molding processing,
We were able to continue producing foam molded products with high efficiency.

As described above, the method of this invention can easily and reliably confirm the completion of cooling in foam molding, as is clear from the examples, and eliminates product defects due to insufficient cooling of the molded product, and waste caused by excessive cooling. It is convenient to improve quality and reduce costs at the same time, and it also makes it easier to determine the timing of the next mold release, greatly contributing to shortening the molding cycle.

In addition, the inventive device used to carry out the above-mentioned inventive method is as follows:
It has a simple and compact structure, and is designed to ensure reliable detection, so it is easy to install in the molds of various foam molding machines and has excellent usability.
The method of the invention described above can be easily implemented.

[Brief explanation of the drawing]

The figures illustrate embodiments of the present invention, and Figure 1 is a schematic cross-sectional view of a molding device equipped with the device of this invention, and Figure 2
The figure is a sectional view of the main part with the air passage closed, Figure 3 is a sectional view of the main part with the air passage open, and Figure 4 is a perspective view of the main part as seen from inside the mold cavity. be. 10,20...Mold, 11,21...
・Steam room, 50...Nozzle part, 51...
・Nozzle component, 52... Pressure receiving plate, 53.
... Air introduction pipe, 54, 55 ... Air feed path, 56 ... Air passage, 57 ...
...Ventilation hole serving as a pressure reduction path, 60...Air pressure regulator, 70...Air flow rate adjustment valve, 80...
...Pressure switch, 90...Pressure gauge, 1
00...Piping.

Claims (1)

[Scope of Claims] 1. A method of performing foam molding by filling a raw material made of expandable thermoplastic resin particles into the cavities of a pair of molds and heating and expanding the raw material with a heating medium such as steam. The fluctuations in the foaming pressure of the molded body that occur during the subsequent cooling process are received and treated as fluctuations in the received pressure, and the fluctuations in the received pressure are converted into pressure fluctuations of compressed air while being sensed and the cooling of the molded body is completed. A method for confirming completion of cooling in foam molding, characterized by automatically confirming the completion of cooling. 2 Pressure is received from a part of the heated and expanded molded body, and compressed air of a predetermined pressure is applied to the pressure-receiving part from the side opposite to the pressure-receiving surface, and when the pressure is reduced as the molded body cools, the compressed air is applied. A method for confirming completion of cooling in foam molding according to claim 1, wherein pressure is sensed so as to cause fluctuations in pressure reduction. 3. In an apparatus that performs foam molding by filling the cavities of a pair of molds with a raw material made of expandable thermoplastic resin particles and heating and expanding the raw material with a heating medium such as steam, a part of the mold is equipped with a nozzle. The nozzle component is equipped with a pressure receiving plate on the side facing the mold cavity, and an air introduction pipe is connected to the opposite side thereof, and the pressure receiving plate receives air from the air introduction pipe. An inlet passage is provided, an air passage communicating with the inlet passage is formed between the nozzle component, and the air passage is communicated with a decompression route, and the pressure receiving plate is used to control the foaming of the molded product in the mold cavity. The air passage is movably provided so that it closes when the pressure is high and opens the air passage when the foaming pressure decreases due to cooling and communicates with the decompression route. A device for confirming completion of cooling in foam molding, characterized by connecting pressure sensitive parts. 4. The device for confirming the completion of cooling in foam molding according to claim 3, wherein the depressurization path is open to the steam chamber of the mold. 5. The device for confirming the completion of cooling in foam molding according to claim 3, wherein the pressure sensitive part comprises a pipe connecting an air pressure regulator, an air flow rate regulating valve, a pressure switch, and a pressure gauge.