JPS5812851B2 - How to manufacture pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous method for manufacturing a pipe having discontinuous protrusions on its surface.

Pipes with such surface protrusions have increased pressure, bending and torsion strength as well as increased surface area.

In addition, an appropriate number of holes are bored mainly in the portion where no protrusion is formed, and these holes are buried underground, for example, and are used for drainage.

The protrusions buried in the ground increase the apparent porosity and increase the contact area with the soil.As a result, the flow of water to be drained becomes better, and the water flows into the recesses on the surface of the pipe, that is, the cylindrical part, and there. It is collected offshore of the pipe through drilled holes and drained appropriately.

Furthermore, if the surface of this pipe is coated with a filter material, it can be used as an underdrain pipe without using materials such as sand plate and rice husk that were conventionally required.

Moreover, it is natural from the viewpoint of its structure that such a pipe can be buried underground and used for supplying water underground.

The present invention will mainly be described below with respect to a method for manufacturing a pipe having a protrusion on its surface, but it is not limited to this, and as long as the structure of the inner peripheral wall surface of the mold used is appropriately selected, any method can be used. Of course, the present invention can also be applied to the manufacture of pipes such as bellows pipes.

In a conventional continuous pipe manufacturing apparatus, for example, as shown in FIG. 1, a semi-molten synthetic resin R extruded into a pipe shape from a die b is driven in the direction of an endlessly connected arrow. The pipe is sandwiched between the mold a and compressed air supplied from the air supply pipe C is used to make the pipe adhere to the mold to produce a pipe of the desired shape. Therefore, the gap e between die b and mold a
was structurally unavoidable.

With conventional equipment that has such gaps, when the inside of the pipe is pressurized, the gap swells unnecessarily, making it impossible to build up the pressure necessary for the pipe to stick tightly to the mold, resulting in a pipe that matches the mold. The drawback was that it was not possible.

To overcome this drawback, the smaller the length l of the mold, the smaller the gap e becomes, and the objective can be achieved. However, a new drawback arises: the number of molds increases, which increases the cost of the equipment. Ta.

It is an object of the present invention to provide a continuous pipe manufacturing method that eliminates all of the above-mentioned drawbacks.

According to an embodiment of the present invention, a preliminary blowing step is included so that sufficient pressure can be applied in the main blowing step to produce a pipe according to the mold, and the mold is not conventional. Since it is possible to use a mold that is significantly longer than that of the mold, the number of molds is reduced and the cost of the device is reduced.

Referring to FIG. 2, which is a system diagram for carrying out the continuous pipe manufacturing method according to the present invention, the overall process will be explained first.
The softened synthetic resin extruded from the extruder A is supplied from the die 1 to the pipe forming apparatus B in the form of a pipe.

The pipe forming device will be described in detail later, but as shown in the figure, when a large number of molds each having a plurality of concave portions formed at appropriate intervals on the inner surface are connected endlessly and are driven in the direction of the arrow, A pipe-shaped uncured synthetic resin is inflated by air pressure at the linearly transitioning portion S, and brought into close contact with the peripheral wall surface of the mold in which the recessed portion is formed, thereby forming a pipe in a desired shape.

The pipe coming out of this forming device B is cooled by a cooling tank C, and then subjected to a drilling process by a drilling machine D.

A drilling machine may be provided between the pipe forming device B and the cooling tank C, the structure of which will be described later.

The outer periphery of the perforated pipe is coated with a filter-forming material using a crosshead die E, and then cut to an appropriate length using a length cutter F to complete the process.

Although the cutter F is shown as a reciprocating cart type, other types may be used, and the cooling tank C, crosshead die E, etc. may be of any type depending on the purpose. can.

Referring to FIGS. 3 and 4 showing the details of the pipe forming apparatus BΩ, this apparatus includes a die 1 for extruding a softened synthetic resin P in the shape of a pipe, and a die 1 that is driven endlessly in the direction of the arrow a. a mold 7 and a part S into which the mold preferably transitions linearly;
It mainly consists of sealing devices 3, 4, 5, and 6 arranged in a pipe forming cylinder 10 made of a large mold, and a cooling water and compressed air supply pipe 2 inserted into the forming cylinder 10. It is understood that what is being done.

However, when carrying out the present invention, it is also possible to form a pipe in advance without placing the extrusion die 1 adjacent to the mold 7, and then transfer the pipe to the mold 7 after heating it again to the softening temperature.

In order to form a protrusion on the surface of the pipe, the mold 7 has a required number of four portions 11 of an appropriate size carved on the inner peripheral surface.

As mentioned above, this recess is for forming a protrusion on the surface of the pipe, but for example, when the pipe P is cut and transported,
When the pipes are used in a connected manner at the place of use, it is advisable to form a radially expanding flange portion at the cut portion of the pipe, so in such a case, a concave portion continuous in the circumferential direction is formed.

Furthermore, as mentioned above, a large number of molds are connected endlessly and driven, but the part S where the mold transitions into a straight string shape is configured so that a pipe with a desired cross-sectional shape is formed. ing.

In other words, a mold that is divided into two or more parts, preferably three or more parts (a four-part mold is shown in Fig. 3), has an inner circumferential surface in the desired shape of a circle or a polygon. It is configured to pass through the linear transition portion S while maintaining its shape.

The number of divisions of the mold is preferably three or more in consideration of the subsequent operation of opening the mold.

The first sealing device 3 is mainly used for sizing to regulate the inner diameter of the resin pipe extruded from the die 1, and does not require a high degree of sealing effect, and is placed near the entrance of the pipe forming device B. .

The second sealing device 4 is provided at a distance of approximately one mold length from the sealing device 3, and the other third and fourth sealing devices 5, 6 are arranged at suitable intervals in the linear transition section S. It is located.

Since the first sealing device 3 seals the smooth inner surface of the pipe, its width does not matter much, but the second, third and fourth sealing devices, especially the second and third sealing devices, Since it is necessary to seal the part where the recess 11 is formed on the inner peripheral surface of the pipe, the width of the seal becomes an issue.

The part of the pipe forming cylinder 10' surrounded by the first sealing device 3 and the second sealing device 4 includes a pre-stage where the mold 7 enters from an oblique direction and moves into a straight line. , this part does not maintain the perfect cross-sectional shape of the pipe, and the pressure necessary to form the pipe cannot be applied, so this cylinder 1
0' should also be called a preformed cylinder, and is a pipe forming cylinder 10 formed by the second sealing device 4 and the third sealing device 5.
Since this is the part where sufficient pressure is applied and the pipe is formed into a perfect shape by the mold, it is desirable that the second and third sealing devices perform a complete sealing action.

The second sealing device 4 is particularly important.

Depending on the pressure value inside the pipe-forming cylinder 10'', the sealing device 4
.

For example, if the longitudinal width of the sealing devices 4 and 5 is made longer than the longitudinal dimension of the protrusion formed on the pipe, compressed air will not leak through the space inside the protrusion.

However, since these are all design matters, detailed explanations are omitted.

The portion surrounded by the third sealing device 5 and the fourth sealing device is not necessarily necessary since the pipe is being repaired or hardened, and therefore the fourth sealing device 6 may be insufficient.

A pipe 2 supplying cooling water and air at various pressures passes through a sealing device 3, 4.5 and into a pipe-forming tube 10'.
, 10", 10"', and is configured to supply air or water into these cylinders.

This sealing device is cooled by cooling water because it retains heat due to the resin temperature.

A drilling machine D installed between the pipe forming machine B and the cooling tank C, or between the cooling tank C and the crosshead die E, cuts holes of a desired diameter mainly in the part where the pipe protrusion is not formed. The holes can be drilled dispersedly over the entire surface of the pipe or only on a partial surface.

For example, as shown in FIG. 4, a plurality of cones 25 are attached to a quarter-arc cone holder 24, and the holder 24 is moved forward and backward relative to the pipe P by an air cylinder 20 to make a hole. It is used for processing.

Note that 23 is a piston rod, and 21 and 22 are ports for supplying and discharging air.

Like the cutting machine described in connection with FIG. 2, this drilling machine D is mounted on a reciprocating movable body such as a truck, and is configured to perform intermittent operations with reciprocating motion.

As shown in FIG. 6, the drilling machine D also has an awl 25 planted in a rotating body 26, and this rotating body is installed close to the pipe, so that the awl pierces the pipe one by one as the pipe moves. It may be configured as follows.

Since the overall pipe manufacturing process has already been described, here we will explain only the functions and effects of the pipe forming device B. The pipe P extruded into a pipe shape from the die 1 of the extruder is first sealed by the first sealing device 3. and second sealing device 4
The pipe is guided to a pipe forming cylinder 10' surrounded by a mold 7 which also serves as a take-off.

This forming cylinder 10' portion includes a mold that is moving from diagonally to horizontally, and there are parts where the mold that has been divided into two or more parts has not yet been completely combined. , a somewhat lower fluid pressure is supplied from the supply pipe 2 to maintain the pipe shape.

Therefore, within this cylinder, the pipe is only lightly pressed against the mold and preliminarily deformed.

This portion may be held in pipe shape by a mandrel.

Since the pressure is low, even if the gap e created between the first sealing device 3 and the mold 7 is larger than that of the conventional one, the pipe in this area will not expand unnecessarily, and the swollen part will be re-opened. Compared to pipes formed by compression,
A pipe with excellent strength and quality can be obtained.

In addition, the presence of the gap e is not a problem according to the method of the present invention, so a large mold with a large gap e can be used.
The desired objective of being able to reduce the number of molds used is also achieved.

The pipe preformed in the pipe forming tube 10' is guided into the next forming tube 10''.

Here, sufficient fluid pressure is supplied from the supply pipe 2 to form a complete pipe according to the shape of the mold.

The pipe is led to the last tube 10'' by a mold that also serves as a take-up mold, but this tube is used for correction and hardening, and it is not necessarily necessary to carry out the work inside the mold, so this tube 10'' is omitted. It can be done.

The pipe formed at the portion S where the mold moves linearly in this way is sequentially sent to the next process described in FIG. 2 to complete the product.

As described above, according to the method of the present invention, the inside of the pipe can be sufficiently pressurized, so a pipe that matches the mold can be obtained.
Furthermore, pipes with excellent quality and strength are manufactured.

Since the apparatus for carrying out the method of the present invention can use a large mold, it can be installed at a low cost.

In the crosshead die E, the filter material is supplied to and coats the outer periphery of the pipe in a known manner.

The filter material may be a textile product, a net or a mesh.

Alternatively, it is also possible to extrude the foamed resin into a cylindrical shape to cover the pipe and burst the bubbles to form a large number of small holes, which is convenient because the pipe and the resin plate, that is, the single layer of the filter, adhere to each other at this stage. .

FIG. 7 shows an example of a pipe manufactured according to the present invention.

A discontinuous protrusion T is formed on the pipe P by a mold 7, and a hole H is bored by a drilling machine D.

Furthermore, the filter layer F is coated with a crosshead die E.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the main parts of a conventional pipe manufacturing device, Figures 2, 3, 4, 5, and 6 illustrate embodiments of the present invention. Fig. 3 is a longitudinal sectional view of the pipe forming device, Fig. 4 is a sectional view taken along the line ■-■ in Fig. 3, and Fig. 5 explains the structure of the drilling machine. Fig. 6 is a side view showing another embodiment of the drilling machine, and Fig. 7 is a part of a pipe manufactured according to the present invention. It is a cross-sectional perspective view. A... Extruder, B... Pipe forming device, C... Cooling tank,
D...7L drilling machine, E...crosshead die, F...cutting machine, P...pipe, 1...dice, 2...pressure fluid supply pipe, 3...first sealing device, 4...first 2 sealing device,
5...Third sealing device, 7...Mold, 10'...Pipe forming cylinder.

Claims (1)

[Claims] 1. A first step of preparing a synthetic resin pipe in a softened state; a second step of sandwiching the pipe prepared in the first step between split molds having discontinuous recesses on the inner surface; 3rd stage that transfers with the pinched pipe still in place
step, and a fourth step of blowing and inflating the pipe by supplying pressurized fluid into the pipe during the third step to bring it into close contact with the inner circumferential wall of the mold. It has a continuous manufacturing process, and in this process, the inside of the pipe is equipped with a first sealing device for sizing that regulates the inner diameter of the pipe, and second and third sealing devices that highly seal the inside of the pipe. a supply pipe extends, the third stage takes place between a first sealing device and a second sealing device, the fourth stage takes place between a second sealing device and a third sealing device, and A step of drilling a plurality of holes on the surface of the pipe between the protrusions of the pipe, and a step of inserting the pipe into a crosshead die and extruding the filter material to the outer periphery of the pipe in the form of a cylindrical film to cover it. A method for manufacturing a pipe coated with a filter material, characterized by comprising: