JPS625835A - Thermal bonding process of plastic sheet - Google Patents

Abstract

PURPOSE:To weld a plastic sheet to a steel members in a short time without air intervening therebetween by heating the steel member to high temperature, while keeping the gap between the steel member and the plastic sheet with thermal adhesion property being closely stuck to said steel member by pushing, at the state of being vacuumized. CONSTITUTION:The plastic sheet 1 with thermal adhesion property covers the surface of a steel sheet pile 2, while setting the sheet pile 2 above a heater 4. A pressurizing jig 3 is placed on the sheet pile 2. A clamp 19 is connected to the joint 18 of the sheet pile 2, and the pressurizing jig 3 is connected and fixed to the steel sheet pile 2. While setting the inner pressure of a pressurizing chamber 7, for instance, at about 2kg/cm<2>, sending air from a compressor to said chamber 7, and if a vacuum pump is started and the gap between a rubber film 6 and the sheet pile 2 is sucked by vacuum, the rubber film 6 is expanded by the elevated pressure in the pressurizing chamber 7, whereby the plastic sheet 1 is stuck closely to the sheet pile 2. Then, the sheet pile 2 is heated such that the temperature of the adhesive layer of the plastic sheet 1 becomes adhesive temperature, and thus, the plastic sheet 1 is fuse welded to the sheet pile 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for attaching a thermoadhesive plastic sheet to the surface of a steel material such as a steel sheet pile, and more particularly to a method for thermally adhering a plastic sheet.

BACKGROUND OF THE INVENTION This type of method has been proposed, for example, in Japanese Patent Laid-Open No. 59-224717. This method involves pressing a covering sheet consisting of a cross-linked plastic layer and a thermal adhesive layer onto the surface of a steel sheet pile, and heating the steel sheet pile in advance to raise its temperature, or by heating the sheet pile while pressing the covering sheet. , a method of joining a covering sheet to a steel sheet pile,
The heating temperature of the steel sheet piles for adhesion should be approximately 60 to 250°C, and any suitable device such as a roll, lever, sheet, or hollow mat can be used to press the covering sheet onto the steel sheet piles. In any case, in order to eliminate air between the covering sheet and the steel sheet pile, it is preferable to apply a pressing force sequentially from the center in the width direction of the steel sheet pile toward both sides, as disclosed in the above-mentioned publication. It is described in.

Problems to be Solved by the Invention However, in the above method, since cross-linked plastic is used for the covering sheet, even if the locations where pressing force is applied are sequentially changed to eliminate air between the steel sheet piles, the covering sheet cannot be Although it does not seem to cause abnormalities such as variations in the thickness of cross-linked plastics, cross-linked plastics require cross-linking for their manufacture. ! Since special equipment is required for the treatment, there is a problem that the covering sheet is octavalent, and cross-linked plastics have strong elasticity, so pressing force must be applied for a long time until the adhesive strength is sufficiently high. There are some unavoidable problems.

It is thought that these problems can be solved by using a regular plastic sheet that has not been cross-linked.In that case, the entire plastic sheet should be uniformly distributed to prevent the plastic from flowing when heated and softened. It is desirable to pressurize it and bring it into close contact with the steel sheet pile. However, when pressing the entire plastic sheet uniformly and simultaneously to make it adhere to the steel sheet pile, it is inevitable that air will be trapped between the two. Partial adhesion failure occurs due to intervening layers or bubbles. Such air layers and bubbles can be eliminated by moving the heating points in order from the center in the width direction toward the left and right edges, and gradually expanding the fused area from the center. However, in such a heating method, the heating time is longer than when heating the entire portion of the steel sheet pile to which the plastic sheet is to be bonded at the same time. Therefore, in order to further increase productivity by shortening the heating time, a new method to replace the above-mentioned heating method is desired.

In view of the above-mentioned circumstances, it is an object of the present invention to provide a thermal bonding method that can bond a plastic sheet and a steel material in a short time without intervening air between the two.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention maintains the space between the steel material and a heat-adhesive plastic sheet that is pressed into close contact with the steel material in a evacuated state. This method is characterized in that the plastic sheet is made into a steel material by heating and increasing the temperature.

Function: When pressing the entire plastic sheet almost uniformly to bring it into close contact with the steel material, air will inevitably be trapped between the two, and even if the entire plastic sheet is pressed uniformly, the intervening air will However, in the method of this invention, the remaining intervening air is removed by vacuum suction, and as a result, by heating the steel material and raising its temperature, the plastic sheet is heated. The whole thing is securely bonded to the steel material.

Example Next, embodiments of the invention will be described.

First, to explain the apparatus for carrying out the method of the present invention, FIG. 1 is a schematic longitudinal sectional front view showing the overall configuration, and FIG. 2 is an enlarged view of the section ■ in FIG. Furthermore, FIG. 3 is a schematic plan view, and the apparatus shown here presses a heat-adhesive plastic sheet 1, such as a polyethylene sheet provided with a heat-adhesive adhesive layer, against a steel sheet pile 2, and The structure includes a pressurizing jig 3 equipped with a vacuum suction mechanism to remove air from between the two, and a heater 4 that heats the steel sheet pile 2. The pressurizing jig 3 applies a pressing force to the plastic sheet 1 using fluid pressure such as compressed air, and has a fixed elastic material such as rubber i16 on the outer surface side of a steel frame 5 having a shape similar to that of the steel sheet pile 2. They are arranged at intervals, and their peripheral parts are fixed to the steel frame 5. Therefore, a pressurizing chamber 7 is formed between the rubber membrane 6 and the II frame 5, and the rubber membrane 6 is connected to the steel sheet pile 2. The pressurizing surface has almost the same shape as the surface of the pressurizing surface. The structure of the part that fixes the peripheral part of the rubber membrane 6 to the steel frame 5 is as shown in FIG. At the same time, a rubber seal 9 is attached to the lower surface of the holding plate 8, and the rubber membrane 6 is attached by a bolt 10 that passes through these from below and is screwed into the SL frame 5.
, a presser plate 8, and a seal rubber 9 are integrally fixed to the steel frame 5. Of these, presser plate 8
The seal rubber 9 also constitutes a part of the vacuum suction mechanism, which will be explained below.

That is, the side edges of the presser plate 8 and the seal rubber 9 are located slightly apart from the edge of the plastic sheet 1 sandwiched between the rubber 16 and the steel sheet pile 2, and are located at a distance from the edge of the steel sheet pile 2. The width is set to be such that it can be sandwiched between the upper surface and the rubber membrane 6, and therefore, the seal rubber 9 maintains airtightness between the rubber 116 sandwiching the plastic sheet 1 and the steel sheet pile 2. It has become. In addition, a plurality of ventilation holes 11 are formed at regular intervals in the presser plate 8, opening both at the inner end surface thereof, that is, the end surface facing the edge of the plastic sheet 1, and at predetermined locations on the upper surface. This ventilation hole 11 may be formed by perforating the presser plate 8.
Alternatively, the holding plate 8 may be grooved and the opening on the upper or lower side of the groove may be closed with the rubber m6 or the sealing rubber 9 to form a hole. A second ventilation hole 12 that communicates with the entrance on the upper surface of the presser plate 8 of each of the ventilation holes 11 is formed by penetrating the M-made frame 5 and the rubber membrane 6 in the thickness direction thereof. Copper pipes 13 are connected to the open ends of the steel frames 5 through steel pipe joints 14, respectively.

Each copper tube 13 is connected to a header 15, and the header 15 is connected to a vacuum pump (not shown).

A supply/exhaust port 16 for supplying and discharging compressed air to and from the pressurizing chamber 7 is provided at the center in the longitudinal direction of the A4 frame 5, and an air hose 1 is provided which communicates with a compressor (not shown).
7 is connected to the air supply/exhaust port 16. Further, on the upper surface of both left and right sides of the sly frame 5, a clamp 19 whose tip end engages the joint part 18 of the steel sheet pile 2 from below is arranged so as to rotate around the bin 21 attached to the bracket 20. Therefore, the clamp 19 is connected to the joint part 18.
By engaging the pressing jig 3 and the steel sheet pile 2 to integrate them, the seal rubber 9 comes into close contact with the upper surface of the end of the steel sheet pile 2, and the airtightness between the rubber membrane 6 and the steel sheet pile 2 is improved. It is designed to hold. Furthermore, the #l frame 5 has a reinforcing plate 2.
2 are arranged at regular intervals in the longitudinal direction, and the end of the moving arm 23 is connected to the reinforcing plate 22.

The header 15 is attached to the steel sheet pile 2 at the upper end of the reinforcing plate 22.
is fixed along the longitudinal direction.

In addition, the heater 4 is a plastic sheet 1 of the steel sheet pile 2.
The heating wire 2'4 has a plurality of heating wires 2'4 arranged in the longitudinal direction on the opposite side to the side to which the steel sheet pile 2 is pasted, and the steel sheet pile 2 can be heated to the desired position by adjusting the current appropriately. It is designed to heat up to a certain temperature.

Next, a detailed description of the present invention using the above-mentioned device will be given. First, the target steel sheet pile 2 is installed above the heater 4, and the surface of the steel sheet pile 2 is covered with a thermoadhesive plastic sheet 1. Then, place the pressure jig 3 on the steel sheet pile 2 so as to sandwich the plastic sheet 1 therebetween, and connect one of the clamps to the joint of the steel sheet pile 2. ! 2118
The pressurizing jig 3 is connected and fixed to the steel sheet pile 2 by engaging with the pressurizing jig 3. In this state, the seal rubber 9 is pressed against the upper surface of the end of the steel sheet pile 2, so that the seal rubber 9 maintains the airtightness between the rubber membrane 6 sandwiching the plastic sheet 1 and the surface of the steel sheet pile 2. has been done.

Therefore, air is sent from the compressor to the pressurized chamber 7, and the internal pressure is set to, for example, around 2Ω/'d, and the vacuum pump is started to connect the header] 5, the copper pipe 13, and each vent hole 12.11. When vacuum suction is applied between the rubber l116 and the steel sheet pile 2 through The sheet 1 and the steel sheet pile 2 are attracted to each other, and as a result, the plastic sheet 1 is brought into close contact with the steel sheet pile 2 with substantially uniform pressure. Then, while maintaining this state, the heating wire 24 is energized to heat and raise the temperature of the steel sheet pile 2 so that the common layer of the plastic sheet 1 reaches the bonding temperature, and the plastic sheet 1 is attached to the steel sheet pile 2 by M'fI. let In that case, the entire bonding layer of the plastic sheet 1 reaches the bonding temperature almost simultaneously and is fused, but the space between the rubber membrane 6 to which the plastic sheet 1 is sandwiched and the steel sheet pile 2 is as described above. Since it is evacuated, air is not drawn into the markings, and as a result, the entire plastic sheet 1 is reliably bonded to the steel sheet pile 2.

Effects of the Invention As is clear from the above explanation, in the method of the present invention, a heat-adhesive plastic sheet is pressed onto a steel material such as a steel sheet pile with a substantially uniform pressing force, and the heat-adhesive plastic sheet is brought into close contact with the steel material such as a steel sheet pile. Vacuum suction is applied to remove air, and the plastic sheet is fused by heating and heating in that state, so even if the entire part to be bonded is heated at the same time and W1@ is performed, it will be bonded reliably without drawing in air. can do. That is, in the method of the present invention, the entire fusion of the plastic sheets to be pasted can proceed at the same time.
The heating time is short, which can increase productivity. Furthermore, since the entire area to which the steel plastic sheet is to be pasted can be heated to a predetermined temperature at the same time, primary effects such as temperature control being made easier by 1J can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional front view of an apparatus for carrying out the method of the present invention, FIG. 2 is an enlarged view of section 2 in FIG. 1, and FIG. 3 is a schematic plan view. 1...Plastic sheet, 2...Steel sheet pile, 3
...pressure jig, 4...heater, 6...rubber membrane,
7... Pressure chamber, 9... Seal rubber, 11...
-Vent hole, 12...Second vent hole, 13...Copper tube, 15...Header, 24...Heating wire.

Claims (1)

[Claims] In adhering a heat-adhesive plastic sheet to a surface of a steel material with a uniform pressing force, and heating and raising the temperature of the steel material to fuse the plastic sheet to the steel material, the plastic sheet and the steel material are bonded together. A method for thermal bonding of plastic sheets, characterized by heating and increasing the temperature of a steel material while maintaining a vacuum state between the spaces between the sheets.