JPH0442187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a water-permeable uneven sheet used as a drain material or soil reinforcing material in civil engineering work, and a water-permeable uneven sheet obtained by this manufacturing method.

Conventionally, as a method for manufacturing mesh-like uneven sheets,
By meshing an upper die with a wave-shaped cutting edge and a lower die with a straight cutting edge, slits are made alternately at regular intervals in the heat-softened thermoplastic synthetic resin sheet, and at the same time it is formed into a wave shape to form a mesh. A method (Japanese Unexamined Patent Publication No. 49-20261) is known.

However, in the conventional method described above, if an attempt is made to increase the unevenness, the mesh itself must become larger, and there is a drawback that the unevenness of the sheet and the size of the through hole cannot be freely adjusted. In addition, the shape of the sheet is limited to a wave shape, and there is a drawback that the selection range of other shapes is limited. Therefore, it is difficult to obtain a sheet in a form suitable for the intended use using conventional methods.

An object of the present invention is to enable the size of the pores and the shape and size of the unevenness to be freely set, thereby making it possible to obtain a water-permeable uneven sheet that matches the intended use.

That is, the present invention forms a large number of slits in a sheet and then performs uneven molding on the sheet to give the sheet a desired uneven shape, and at the same time, the slits are expanded to provide water permeability as transparent holes. A method for manufacturing a textured sheet, and a sheet obtained by the method. The present invention provides a water-permeable uneven sheet having a large number of uneven parts having a height-to-maximum diameter ratio of 2:1 or less, which are formed alternately on both the front and back surfaces, and a large number of through holes.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of the manufacturing method according to the present invention, in which 1 is a thermoplastic synthetic resin sheet;
Both ends are clamped by a conveying means 2 such as a chain or a belt, and the conveyor is conveyed continuously from above to below.

First, a cutting blade 3 is intermittently pressed against the sheet 1 to form a large number of slits 4 as clearly shown in FIG.

The slits 4 may be formed in the sheet 1 by simply pressing the sharp cutting blade 3 against the sheet 1 to make a cut, but it is possible to form the slits 4 by heating the cutting blade 3. At the same time, it is preferable to partially dissolve the synthetic resin in the cut portion. In this way, as shown in FIG. 3, the periphery of the slit 4 is bulged and reinforced by the molten synthetic resin, making it difficult for the slit 4 to tear during the subsequent uneven molding.

The optimal arrangement of the slits 4 is a staggered pattern as shown in FIG. 2, but they may also be aligned or arranged in both vertical and horizontal directions.

The sheet 1 with the slits 4 formed thereon is transferred to a heating means 5 such as an infrared heater, and while passing therethrough is heated and softened to a temperature suitable for thermoforming.

Next, the heated and softened sheet 1 is sent between a pair of molds 6a and 6b, where it is subjected to uneven molding. The molds 6a, 6b connect a large number of molding pins 7a, 7b alternately located to the substrate 8.
a, 8b, and are moved forward and backward by hydraulic devices 9a, 9b. Moreover, the pair of molds 6a, 6b are provided with a hydraulic device 11a, a hydraulic device 11a,
11b, it can be moved up and down.

First, as shown in FIG.
b, the frame 10 is moved downward in synchronization with the transport speed of the sheet 1, and is moved forward by the hydraulic devices 9a and 9b, and as shown in FIG. 5, the sheet 1 is formed into the closed state. Push it out using pins 7a and 7b. The molds 6a and 6b then continue to descend, and after being cooled until the sheet 1 can maintain a constant shape, they are released, and return to the upper position shown in FIG. Repeat the stretching operation.

As shown in FIG. 6, by the uneven molding of the molds 6a and 6b, unevenness is formed alternately on both sides of the sheet 1, and at the same time, the forming pins 7
During the elongation by a and 7b, the slits 4 of the sheet 1 are expanded to form through holes 4', imparting water permeability. In addition, the molded pins 7a, 7
By changing the thickness, length, cross-sectional shape, etc. of b, various forms of unevenness can be provided on the sheet 1.

Here, the timing at which the molds 6a, 6b are brought into the open state and returned to the upper position is the timing when the molds 6a, 6b are returned to the upper position.
Any time may be used as long as the sheet 1 sandwiched between the molds 6b and formed into a predetermined shape is cooled to the extent that it can maintain a constant shape.
In order to improve efficiency by shortening and speeding up and down reciprocation of the sheet 1, it is preferable to forcibly cool the sheet 1 sandwiched between the molds 6a and 6b.

In addition, only the portion of the sheet 1 held by the molds 6a, 6b can be sufficiently cooled in a short time, and the return time from the lower position of the molds 6a, 6b to the upper position and the transport speed of the sheet 1 can be reduced. By appropriately adjusting the relationship between . That is, by aligning the upper end of the previously formed uneven shape with the lower end of the subsequently formed uneven shape, it is possible to obtain a series of long molded products. At this time, in order to prevent the sheet 1 from being cooled between the heating means 5 and the molds 6a and 6b, it is preferable to cover the space between the heating means 5 and the molds 6a and 6b with a bellows-shaped cylinder or the like to maintain heat.

As shown in FIG. 5, as a forced cooling method for the sheet 1 placed between the forming molds 6a and 6b, each of the forming pins 7a or 7b of the other forming mold 6a or 6b forming a pair is cooled. Nozzle holes 12a, 12b are provided in the air plates 8a, 8b, and the nozzle holes 12
It is preferable to send cold air or spray water from a and 12b. The cold air and spray water sent from each nozzle hole once hit the sheet 1 that is in close contact with the tips of the forming pins 7a and 7b, and then are slowly diffused, so that the air is stretched between the forming pins 7a and 7b. Rapid cooling is possible without deforming the sheet 1 in its current state. Moreover, even when cooling with water is attempted, the supplied water falls directly downward, so there is no fear of cooling the sheet 1 that follows. Falling water can also be collected below and used for cooling.

In addition to the above-mentioned thermoplastic synthetic resin sheet, the sheet used in the present invention can be widely used as long as it has ductility, such as a sheet-shaped metal plate.
Specifically, hard polyvinyl chloride, polystyrene, polyethylene (HDPE), polycarbonate,
Polyvinyl chloride, nylon, polyester,
These are single-layer or laminated synthetic resin sheets such as polypropylene, or metal plates such as aluminum, copper, and soft iron. Furthermore, heating and softening prior to molding is effective in the case of synthetic resin sheets, but it is not necessarily necessary to perform softening in the case of metal plates.

When performing uneven molding by elongating with a forming pin as described above, the head of the forming pin may be a flat surface, but it is preferable to form a concave curved surface. This is because the slits formed in the sheet in the portions that come into contact with the forming pins are also relatively easy to push out. Further, the present invention is not limited to such uneven forming by elongating a forming pin, but may be performed using other forming methods such as vacuum forming or pressure forming. However, in vacuum forming and pressure forming, air leaks from the slits formed in the sheet during forming.
Because it becomes necessary to form all at once using strong vacuum force or compressed air force, or it becomes necessary to overlap the sheet to be formed with a flexible sheet to prevent air leakage, the above-mentioned thrusting with forming pins is not necessary. Irregular forming by stretching is optimal.

In the above-mentioned example explained based on the drawings, a water-permeable uneven sheet is formed continuously, but it may also be done in batches by forming slits and forming unevenness for each sheet of the required size. Of course.

In the present invention, the slits formed in the sheet are
As described above, they can be formed in various directions and arrangements, but their lengths and intervals do not necessarily have to be uniform. Although the length and spacing vary depending on the size of the unevenness to be formed and the purpose, the length is usually about 1 mm to 30 mm, and the spacing is about 1 mm to 10 mm. However, in order to obtain uniform water permeability over the entire sheet, it is preferable to form slits of equal length at regular intervals throughout the sheet. Further, the length of the slit is preferably equal to or less than the maximum diameter of the convex portion to be formed. If the length of the slit becomes too long compared to the diameter of the convex part,
This is because the convex portion becomes brittle.

The unevenness to be formed on the sheet is not limited to the regular one that is formed alternately on the front and back sides as shown in Figure 6, but it is also possible to form protrusions on one of the front and back sides, or to make the unevenness irregular. . In short, it is sufficient if bulkiness in the thickness direction of the sheet can be imparted within a certain area. However, in order to obtain the same water permeability regardless of whether the front or back surfaces are used upward, it is preferable that the convex portions are not formed so as to be biased toward only one of the front and back sides. In addition, the unevenness may be formed densely close to each other, or may be formed at a certain interval, but it is important to spread the slits as uniformly as possible over the whole to reduce variations in water permeability. In order to provide well-balanced rigidity and flexibility to the front and back sides, it is preferable that the size of the unevenness be uniform on the front and back sides.

On the other hand, the ratio of the height of the convex portion to its maximum diameter is 2:1.
It is preferable that it is smaller than . Especially one on one
It is preferable that the convex portions have a rather zigzag shape at the front and rear. This is to ensure that the convex portion maintains sufficient strength even after the slit is expanded to form a through-hole portion.

In other words, by providing uneven parts that are formed alternately on both the front and back sides, it is possible to equalize water permeability on the front and back sides, maintain well-balanced rigidity and flexibility, and reduce the height and maximum diameter ratio of the uneven parts. When the ratio is 2:1 or less, sufficient strength can be imparted and excellent functionality can be exhibited when used as a drain material or the like.

According to the method of the present invention, the slits are formed in a sheet, and the slits can be expanded to form transparent holes when the sheet is textured. By adjusting the size of the unevenness, the size of the through hole can be freely set. In addition, the irregularities formed on the sheet can be widely determined by selecting the shape of the forming pin and the mold, making it easy to obtain a water-permeable irregular sheet suitable for the intended use.

Example 1 Slits with a length of 5 mm were formed in a staggered manner with a knife at 5 mm intervals on a hard polyvinyl chloride sheet having a thickness of 500 μm and a size of 50 cm square.

After fixing the four circumferences of the sheet to a frame and heating and softening it to about 150° C., it was molded into irregularities using a pair of molds in which cylindrical molding pins with a diameter of about 1 cm were implanted at intervals of 3 cm. The head of the molding pin was semispherical with a radius of 5 mm.

After the mold is closed by passing the sheet, about 10
When the sheet was kept in that state for a few seconds and then taken out, a water-permeable uneven sheet as shown in FIG. 6 was obtained. The height of the convex part is approximately 1.5cm,
The maximum diameter of the top is approximately 1 cm, and the height of the convex portion: maximum diameter =
The ratio was 1.5:1.0 (<2:1), and the permeable portion was approximately diamond-shaped and uniform in size.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the method of the present invention, Fig. 2 is a perspective view of a sheet with slits formed, Fig. 3 is a cross-sectional view of the sheet near the slits when the slits are formed with a heated cutting blade, and Fig. 4 The figure is a perspective view of the mold in an open state, FIG. 5 is a sectional view of the mold in a closed state, and FIG. 6 is a perspective view of the resulting water-permeable uneven sheet. 1: sheet, 4: slit, 4': through hole.

Claims (1)

[Scope of Claims] 1. After forming a large number of slits in a sheet, the sheet is subjected to uneven molding to give the sheet a desired uneven shape, and the slits are expanded to provide water permeability as transparent holes. A method for manufacturing a water-permeable uneven sheet. 2. A water-permeable uneven sheet having a large number of uneven parts having a height to maximum diameter ratio of 2:1 or less and a large number of through holes formed alternately on both the front and back surfaces.