JPS6258882B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hot platen for a hot press that bonds a plurality of plates by heating and pressing, or bonding a sheet material to the surface of a plate by heating and pressing. Related to temperature control method.

[Prior Art] Hot presses, whose heating platen can quickly and accurately control the temperature, have ideal characteristics that allow high-quality products to be processed in a short time.

A hot press is used, for example, to attach a surface material such as thinly sliced wood veneer, synthetic resin film, or paper to the surface of a wooden plywood board. However, all board materials have an equilibrium moisture content of 10.
% of water, but this water content is
When applying a surface material, especially if the surface material is not permeable to steam, when the press is released after hot pressing, the surface will blister due to steam, which has become the subject of product complaints. This is inevitable because when decompressing the hot platen, the temperature of the hot platen is over 100℃, and the pressure is decompressed above the boiling point of water. To avoid this,
The base plate material is subjected to secondary processing over a long period of time in an absolutely dry state or at a low heat-pressing temperature.
For this reason, the cost and material management for drying the board material is difficult. This drawback can be overcome by setting the temperature cycle of the hot platen of the hot press to a high temperature at the beginning of the press, and then increasing the temperature to around 100°C during hot pressing. If the initial temperature is high to speed up heat transfer and shorten the cycle, then the temperature can be lowered to around 100℃ when the press is completed and the pressure is released.
The saturated vapor pressure of the water inside the board material is around 1 Kg/cm ² absolute, and the surface material will no longer be punctured.

The harmful effects of moisture content occur not only in the secondary processing of applying a surface material to a board, but also in the production of plywood, in which multiple boards are glued together. Currently, the temperature control of plywood hot presses is performed by keeping the hot platen temperature at a constant temperature of 110℃, but this is because increasing the temperature higher than this increases the vapor pressure of the moisture contained inside the plywood, and when the press depressurizes. , vapor pressure overcomes adhesive force,
It has the disadvantage of causing delamination, or so-called banking. If you can control the temperature at the beginning of pressurization to be high and the temperature at the time of decompression to be low, you can heat it up quickly and prevent punctures, which shortens the cycle and prevents punctures, which have been a bottleneck during production. The two major problems can be solved at once.

By the way, in order to prevent the harmful effects of moisture content, if the board is dried to a moisture content of 30% or less, it will shrink.
In large factories, this loss can amount to around 300 million yen per year.

If you bring a board with a moisture content of about 30% to a hot press and heat press it, the current heat press of 110 degrees Celsius takes time, and it has the disadvantage that it will bank when it is decompressed.

The present inventor has developed a heating and cooling method in which air is forcedly blown onto a hot plate heated with steam, the steam is removed with this air, water is sent in, and the hot plate is cooled with water (Japanese Patent Publication No. 53-26336). Public bulletin). This method is
Water can be fed into the hot platen relatively smoothly, but the drawback is that it is difficult to accurately control the temperature of the hot plate, especially when cooling the hot plate. If the hot platen is cooled to a lower temperature than necessary before being decompressed, not only does it take a long time to reheat it with steam, but the steam consumption also increases, leading to an increase in running costs.

The ideal temperature during hot platen decompression is as low as 100
℃, preferably below 100℃. If the hot platen is cooled with water, it is difficult to control the hot platen temperature close to 100°C unless the amount of water supplied is extremely precisely controlled. When the temperature of the hot platen is detected to control the state of water supply to the hot platen, the temperature of the hot platen continues to decrease even after the water supply is stopped. For this reason,
It is difficult to create a structure that allows the temperature to approach 100°C during decompression, yet does not allow cooling from 100°C to an unnecessarily low temperature. This is due to the large amount of water pumped into the hot platen further cooling the hot platen, and also due to the mass and specific heat of the hot platen and the plate material being pressed, as well as the temperature and amount of water fed. This is due to the fact that the cooling temperature of the heating platen fluctuates significantly, and it is difficult to determine the amount of water to be supplied by taking into account a large number of factors.

This is a hot platen cooling method for hot cored presses, and in order to prevent extremely rapid cooling in the initial stage of cooling,
A method has been developed in which a mist of fluid is flowed before the cooling water is pumped into the cooling circuit of the hot platen to cool the hot platen (Japanese Patent Laid-Open No. 198101/1983).

This method uses atomized fluid that is pumped before the cooling water to prevent extremely rapid cooling in the initial stage of cooling.
Although it has the effect of preventing the heating plate from cracking, etc., the heating plate is cooled to a lower temperature than necessary because it is cooled to the set temperature with fog and then rapidly cooled to room temperature by pumping cooling water.
The drawback was that reheating with steam took a long time, increasing the amount of steam consumed and increasing running costs.

Further, the conventional method described above in which water is forced out with air and then steam is passed through the press has the drawback that it takes time to push out the water and the press cycle cannot be shortened. Therefore, the hot cold press, in which the hot platen is cooled with water, has a considerably long cycle time of several tens of minutes or more, and a hot press with a press time of 100 seconds or less cannot be used.

[Structure and Object of the Present Invention] In order to eliminate the above-mentioned drawbacks of the conventional technology, the present invention replaces a hot plate heated with steam with a mist of water, which is a mixture of water and air, instead of using water. An important object of the present invention is that the atomized water sent into the heating platen heats the heating platen to 100°C by generating a large heat of vaporization of 540 calories per gram. Until it cools down, it takes away a significant amount of heat, and the heat of vaporization quickly heats the heating plate up to 100% with a small amount of water.
℃, and after cooling to 100℃, water is sprayed and mixed into the air, and the heating plate cooling capacity per unit volume is so small that it is incomparably smaller than water. For cooling, the heated platen is not supercooled more than necessary by the injected mist, and even though the heated platen quickly approaches 100℃ and is cooled, the temperature of the heated platen is accurate at the time of depressurization and thereafter. Moreover, since the fog can be easily discharged with air or steam, the temperature of the heating platen can be increased quickly during reheating. The cycle time can be shortened by pressing in a short amount of time, and the harmful effects such as delamination due to moisture contained in the board can be greatly reduced.Furthermore, there is no need to completely dry the board to be pressed, so the drying cost of the board can be reduced. To provide a method for controlling the temperature of a hot press platen, which can minimize loss due to drying.

[Means for Solving Conventional Problems] The hot press heating platen temperature control method according to the present invention heats the hot platen by passing heated and pressurized steam through the hot platen, and heats the hot platen after a predetermined period of time has elapsed after the product is sandwiched. After that, the temperature of the heating plate is lowered before decompressing, and after decompressing, the product is replaced and the process of reheating is repeated.

During the cooling process of the hot platen before depressurization, water is sprayed into the hot platen in the form of a mist, and this sprayed water also cools the hot platen to 100℃.
Cool nearby.

After the product is removed, it is reheated by passing heated steam instead of mist water to heat the heating plate.

[Preferred Embodiments] Hereinafter, embodiments of the present invention will be described together with a hot press in which the present invention is utilized.

The hot press shown in FIG.
and a pressing means for hot-pressing a plate material 2 on which a surface material such as a veneer or a synthetic resin film to be bonded is layered on the surface between the heating platen 1, and a heating platen 1 with either steam or mist. The steam chamber 3 is equipped with a steam chamber 3.

The heating plate 1 has a steam passage bored through it, pressurized and heated steam is forced into this passage to heat it, and a mist of water mixed with air is sent in to cool it. be done.

The pressing means is a cylinder 4 that pushes up the hot platen 1 from below, and this cylinder 4 also pushes up the hot platen 1 and presses the plate material 2 between the hot platens 1.

The steam chamber 3 is connected to the hot platen 1 via a flexible hose 5, and the steam sent here is sent from the hose 5 to the hot platen 1.

The steam chamber 3 communicates with an air passage 8 and is connected to a water nozzle 9 so that water is blown together with air to become a mist, and the mist is sent from a hose 5 to the heating plate 1. Water is sprayed from
This water is atomized by the air in the air passage 8 and sent into the steam chamber 3.

In the steam chamber 3 shown in FIG. 3, a nozzle 7 for blowing water and air together in a mist form is arranged near the open end of a connecting pipe 6 to which a hose 5 is connected. From the nozzle 7, pressurized water and air are sprayed in the form of mist toward the connecting pipe 6.

A gap for steam injection is formed between the outer periphery of the tip of the nozzle 7 and the open end of the connecting tube 6, and air in the steam chamber is sent into the connecting tube 6 together with mist water from this gap.

The heating plate 1 shown in FIG. 4 has a nozzle 10 directly fixed to it which blows water and air in the form of a mist.

As shown in FIG.
When fixing, one or more nozzles 10 are fixed in communication with the steam passage of the hot platen 1.

The mist water supplied to the heating plate 1 is supplied to the solenoid valve 11.
supply and stop are controlled. The solenoid valve 11 is closed by the output of a temperature sensor 12 which is fixed to the hot platen 1 and detects the temperature of the hot platen surface. That is, when the temperature of the heating platen 1 falls below the set temperature, the solenoid valve 11 is closed and water spraying is stopped. This electromagnetic valve 11 is opened by a control means that controls the movement of the entire apparatus including the cylinder 4, and is opened after a certain period of time when the plate material 2 is heated and pressed.

The operation of the hot press configured in this way is
This will be explained based on FIG.

First, steam is passed through the steam passage in the heating platen 1 to heat the entire heating platen, and the plate material 2 with the surface material layered thereon is sandwiched and pressed. After a certain period of time has elapsed, the pressing pressure on the plate material 2 is reduced and the pressed state is further maintained. Before or after reducing the press pressure, stop the steam supply into the hot platen 1,
The hot platen 1 is cooled by spraying water in the form of mist into the steam passage in the hot platen 1 instead of steam. When the plate material 2 is pressed, the heat platen 1 loses heat to the plate material 2 and its surface temperature decreases, but it is further cooled by the atomized water. The surface temperature of the heating plate 1 before depressurization is, for example, 95°C to 107°C, preferably 98°C to
After cooling to 105℃ and decompressing, the plate material is taken out from between the hot platens. This process is then repeated to bond the boards together.

By the way, when blowing steam into the hot platen 1, the solenoid valve 14 of the steam passage 13 is opened, and when blowing water into the hot platen 1 in the form of mist, the water passage 15 and the air passage 8 are opened.
Open the solenoid valves 11 and 16.

When bonding 3 mm thick plywood boards by hot pressing three sheets of lauan, the primary pressure for pressing the boards is 8Kg/cm ² , the secondary pressure for pressing the boards is 4Kg/cm ² , The maximum temperature of the hot platen when pressing a plate is 150℃, and when the temperature of the hot platen during decompression is set to 103℃, the first press time is about 60 seconds, the second press time is 10 seconds, and the overall temperature is 150℃. About 70 seconds was appropriate.

Also, when bonding a polyethylene sheet to the surface of a board as a secondary processing of the board, the maximum temperature of the heating plate should be
It was appropriate to set the temperature at 160°C, the temperature at depressurization to 100°C, and the time for one cycle to be about 150 seconds.

[Effects of the present invention] The hot press hot platen temperature control method of the present invention is as follows:
Instead of water, a mist of water and air is blown into the heated platen to cool the platen.
Even in the form of a mist, water absorbs 540 calories per gram from the heating plate, and a small amount of water can rapidly cool the heating plate to 100 degrees Celsius. Therefore, the hot platen is smoothly cooled to close to 100°C, and the mist water smoothly flows into the entire steam passage in the hot platen, thereby uniformly cooling the entire hot platen. When the hot plate is cooled to below 100℃, the mist of water takes only 1 calorie per gram, which is 1/540th of the heat from the above state, and the water expands into a mist with air. Because of this, the cooling capacity per unit volume is low, and even if a large amount of this is fed into the hot platen, the hot platen will not be overcooled. Therefore, it is easy to control the amount of mist water fed, and the temperature of the heating plate can be precisely controlled.

This, combined with cooling the hot platen to around 100°C, shortens the reheating time of the hot platen, reduces steam consumption, and reduces running costs.

Furthermore, the mist that has cooled the heating plate can be easily and quickly removed with steam or air, reducing the time for reheating with steam and shortening the cycle time. The cycle time can be further shortened by increasing the maximum temperature of the heating platen to eliminate the harmful effects of contained moisture, and productivity can be significantly improved.

Furthermore, even though the maximum temperature of the heating plate can be high, the temperature during decompression can be kept low, so delamination and bulging of the top sheet do not occur during decompression.
High quality products can be pressed. Furthermore, since there is no need to completely dry the board material, the cost required for drying can be greatly reduced, and the loss of board material due to drying can be minimized, among other benefits.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of a press apparatus in which the hot press hot platen temperature control method of the present invention is used;
The figure is a graph showing the state of press pressure and temperature changes,
FIG. 3 is a sectional view showing how the nozzle is attached, and FIG. 4 is a sectional view of the heating plate. 1...Heating plate, 2...Plate material, 3...Steam chamber, 4...Cylinder, 5...Hose, 6...
Connecting pipe, 7... Nozzle, 8... Air path, 9... Nozzle, 10... Nozzle, 11... Solenoid valve, 12...
... Temperature sensor, 13 ... Steam path, 14 ... Solenoid valve, 15 ... Water channel, 16 ... Solenoid valve.

Claims (1)

[Scope of Claims] 1 Heat pressurized steam through a hot platen, and after a predetermined period of time has elapsed since the product is sandwiched, the temperature of the hot plate is lowered before decompressing, and the product is heated after decompressing. In the hot press heating platen temperature control method, which repeats the process of replacing and reheating, water is sprayed into the heating platen in the form of a mist during the heating platen cooling process before depressurization, and this sprayed water is used to cool the heating platen. A method for controlling the temperature of a hot press platen, which is characterized by cooling the product to around 100°C, then taking the product out, and heating it again by passing heated steam through the hot platen. 2 After pressing the product and before decompressing, spray water in the form of a mist into the hot platen to raise the surface temperature of the hot platen to 95°C to 107°C.
A method for controlling the temperature of a hot press platen according to claim 1, wherein the hot press platen temperature is cooled to a temperature of .degree.