JPH0260914B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to a method for dismantling spiral pipes used in applications that must be dismantled after use, for example, as formwork materials for forming concrete cylinders such as columns and bridge piers. It is related to.

(Prior Art) Recently, instead of synthetic resin tubes obtained by conventional extrusion molding methods, synthetic resin tubes having longitudinal mutually engaging ribs on both ends are spirally wound. So-called synthetic resin pipes are increasingly being used as piping materials for ducts, transportation, drainage, etc.

The characteristics of this spiral tube are as follows: (1) The belt-shaped body rolled into a single roll is transported to the site, and simple pipe manufacturing equipment (for example,
-61434, published patent No. 57-501229, etc.), the tube can be made into a tube by simply winding it in a spiral on-site, so the tube can be transported like conventional methods. (2) There is also the advantage that a tube of any diameter can be easily obtained.

Conventionally, when winding the above-mentioned synthetic resin belt-like body in a spiral shape to form a pipe body, as described in, for example, Japanese Patent Publication No. 57-501229, an engaging rib is formed immediately before the winding. An adhesion method is used in which a solvent-based adhesive is applied to the surface of the band and the socket is wrapped, or a heat fusion method is used in which the engaging rib of the strip and the socket are heated and fused while being wrapped.

(Problem to be Solved by the Invention) However, when the above spiral tube is used as a formwork material for forming concrete cylinders such as columns and bridge piers, it is necessary to remove the formwork material after curing the concrete. . As means for removing this formwork material, there are a method of cutting the formwork material in the axial direction with an electric cutter and peeling it off, or a method of peeling off the formwork material in a spiral shape without cutting it. However, when cutting with the above-mentioned cutter, there is a disadvantage that the concrete surface is damaged by cutting, and when peeling off the concrete in a spiral manner, the engaging part is firmly engaged with adhesive etc. The disadvantage is that it takes time to unwind.

The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to provide a method for extremely easily disassembling spiral tubes used in applications that require disassembly after use. be.

(Means for Solving the Problems) The method for dismantling a helical tube of the present invention has a longitudinal engagement rib at one end in the longitudinal direction of the base, and receives the engagement rib at the other end edge. A method for disassembling a helical tube having a joint portion where the engaging rib and the socket are mutually engaged by winding a band-like body having a longitudinal socket in a spiral manner, the method comprising: The joint portion is broken in a spiral manner by pulling a core wire buried in a nearby wall or in the socket or a wall in the vicinity thereof to the outside or inward of the spiral tube. .

(Function) In the present invention, the joint portion of the helical tube is spirally formed by pulling the core wire buried in the engaging rib or the wall near the engaging rib or the socket or the wall near the socket outward or inward of the helical tube. Since the joint is broken in a shape, the engagement strength of the joint is extremely reduced.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is an explanatory view partially omitting a state in which a spiral tube is dismantled using the method of the present invention, and 8 shows a strip 1 made of a hard synthetic resin such as hard vinyl chloride resin. A helical tube is manufactured by spirally winding, and 5 is a core wire.

First, the structure of the spiral tube 8 used in the present invention will be explained based on FIG. 2 and subsequent figures.

FIG. 2 is a cross-sectional view showing, with a portion omitted, an example of a band-like body constituting the spiral tube used in the present invention. An engagement rib 3 is integrally provided at one longitudinal end edge of the elongated flat base 2, and a socket 4 is integrally provided at the other end edge. The engagement rib 3 and the socket 4 are each provided upright from the base 2. The engagement rib 3 has an upright portion 31,
The engagement portion 32 is connected to the tip of the upright portion 31. The socket 4 receives the engagement rib 3, and its inner surface has a shape similar to that of the engagement rib 3.
It is designed to approximately match the external shape of the Reference numeral 5 denotes a core wire, which is embedded in the wall of the engaging portion of the socket 4 in the longitudinal direction. The core wire 5 is preferably made of piano wire, steel wire, nichrome wire, or the like with excellent tensile strength.

The position where the core wire 5 is buried may be within the side wall of the socket 4, as shown in FIG. Further, the cross-sectional shape of the core wire is not limited to the circular shape shown in FIG. 2, but may be, for example, semicircular, oval, triangular, diamond, wedge-shaped, inverted V-shape, inverted Y-shape, or the like.

Furthermore, the position where the core wire 5 is buried is the engagement rib 3.
It may be within the walls of In this case, it is preferable to embed the core wire 5 in the upper wall of the engaging portion 32 as shown in FIG. 4. If the core wire 5 has a triangular or wedge-shaped cross section, the socket Walls can be easily destroyed. Furthermore, a groove 41 may be provided in the upper inner surface of the socket 4 in the longitudinal direction. By providing the groove 41, as shown in FIG.
The substantial wall thickness of the socket 4 over which the core wire 5 has to be broken is reduced, making it easier to remove it after use as formwork material.

The groove 41 may be provided on the outer surface of the upper part of the socket 4, or instead of providing the groove 41, a hollow portion may be provided in the upper wall of the socket 4 (not shown).

The thickness of the core wire 5 can be determined depending on the position where it will be buried. For example, when it is buried in the wall of the socket 4 as shown in FIG. It will be difficult to maintain the shape, and if it is made too thin, there is a risk that the core wire will break when it is pulled and breaks the socket wall, so the thickness of the core wire should be 0.3 of the thickness of the socket wall.
It is best to set it to around 0.8 times.

Reference numeral 6 denotes a diagonal rib, which is provided to extend outward from the lower side of the socket 4. The diagonal ribs 6 may be continuous in the longitudinal direction or may be discontinuous.

The extension length and extension angle of the diagonal rib 6 are set such that, when engaged, the tip of the diagonal rib 6 is locked to a flange portion 72 of a later-described reinforcing rib 7 adjacent to the engagement rib 3. , fusion of the engaging rib 3 and rib 7, rib 7
It can be determined according to the height of the

7, 7... are reinforcing ribs, which have a T-shaped cross section and are made up of an upright part 71 and a flange part 72, and extend upright from the base 2 between the engagement rib 3 and the socket 4 at a predetermined interval. A plurality of strips are provided in the longitudinal direction.

The core wire 5 is embedded in the wall of the engaging rib 3 of the strip 1 or in the wall of the socket 4 by feeding the core wire into a mold having a predetermined inner surface shape, and extruding the strip at the same time. Just go.

Next, as an embodiment of the method for dismantling a helical pipe of the present invention, dismantling of a helical pipe used as a formwork for forming a concrete cylinder will be described with reference to FIG.

The helical tube 8 is used to attach the strip 1 shown in FIG. 2 to the outer surface of a cylindrical mandrel having a desired diameter, for example, so that the engaging ribs 3 and the socket 4 are attached to each other so that the ribs 7, 7, . . . are on the outside. It is formed by wrapping them together in a spiral shape. The spiral pipe 8 is used as a formwork material for forming a concrete cylinder, concrete 9 is poured into the formwork material, and after curing, the socket 4 is
The core wire 5 buried in the wall of the socket 4 is pulled in the direction of the arrow (towards the outside of the spiral tube 8), and the wall of the socket 4 is broken in a spiral manner.

The strip 1 is then peeled off in a spiral manner to obtain a concrete cylinder with an undamaged surface.

Further, as in the embodiment shown in FIG. 2, by providing the diagonal rib 6 extending outward from the lower side of the socket 4, when the engaging rib 3 is engaged in the socket 4, the diagonal rib 6 is locked to the flange portion 72 of the rib 7 adjacent to the engaging rib 3, so that the engagement strength of the joint is further increased (see FIG. 5).

In addition, the cross-sectional shape of the engaging rib 3 is different from that shown in the figure.
It may be of any shape; for example, the engaging portion 32 may have a rectangular shape such as a triangle, or may have an uneven surface. Furthermore, the diagonal ribs 6 and the ribs 7, 7, . . . are not necessarily necessary. Furthermore, if the core wire 5 is made of an electrical resistance wire such as a nichrome wire, the core wire can be stretched while being energized to soften the synthetic resin.

In the embodiment described above, the core wire 5 buried in the wall of the engaging rib 3 or the wall of the socket 4 is pulled outward of the threaded pipe 8, thereby destroying the wall of the socket 4 and opening the engaging portion. Although a method has been described in which the helical tube 8 is easily dismantled by extremely reducing the engagement strength, the method of disassembling the helical tube of the present invention is not limited to this.

In other words, although not shown in the drawings, the core wires buried in the wall at the root of the rising portion of the engagement rib or the core wire buried in the wall at the root of the riser portion of the socket are joined by pulling them inward of the spiral tube. It may also be a method of destroying the part. Such a dismantling method in which the core wire is pulled inward of the helical tube can be suitably used, for example, for dismantling a helical tube used as an inner formwork for manufacturing a concrete structure having a cylindrical space.

(Effects of the Invention) The method for dismantling a helical tube of the present invention is configured as described above, and the core wire buried in the engaging rib or the wall near the engaging rib or the socket or the wall near the socket is removed from the outside of the helical tube or Since the joint is characterized by spirally breaking by pulling inward, the spiral tube can be used, for example, as a formwork for forming a concrete cylinder or as an inner formwork for a concrete structure having a cylindrical space. In this case, by pulling the core wire after concrete curing, the joint part is destroyed in a spiral shape, and the engagement strength of the joint part can be substantially reduced. Therefore, the formwork can be easily removed. Furthermore, since there is no need to cut the formwork with a cutter or the like, concrete cylinders or concrete structures with no scratches on the surface or inner surface can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention with a portion omitted; FIG. FIG. 3 is a cross-sectional view showing another example of the band-like body with some parts omitted, FIG. 4 is a cross-sectional view showing still another example of the band-like body with some parts omitted, and FIG. FIG. 6 is a partial cross-sectional view showing the joint portion of the belt-like body shown in the figure, and FIG. 6 is a joint part of the belt-like body shown in FIG. 4, which is wound spirally. 1... Band-shaped body, 2... Base, 3... Engagement rib,
31... Upright part, 32... Engaging part, 4... Socket, 41... Concave groove, 5... Cord wire, 6... Diagonal rib, 7... Rib, 8... Spiral tube.

Claims (1)

[Claims] 1. The above-mentioned engagement is achieved by spirally winding a band-shaped body having a longitudinal engagement rib on one longitudinal end edge of the base and a longitudinal socket for receiving the engagement rib on the other end edge. A method for dismantling a helical pipe having a joint in which a coupling rib and a socket are engaged with each other, the method comprising: a core buried in a wall at or near the engagement rib or a wall at or near the socket; A method for dismantling a helical tube, characterized in that the joint portion is destroyed in a spiral shape by pulling a wire outward or inward of the helical tube.