JPH0415464Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for manufacturing a composite cladding tube that simultaneously coats the outer surface of a metal tube with two types of plastics having different physical properties.

[Conventional technology]

Conventionally, composite cladding tubes are often used, in which the outer surface of a metal tube is coated with two types of plastic coatings with different physical properties, such as a spirally coated plastic strip with corrosion resistance on the lower layer and a plastic strip with excellent thermal or mechanical properties on the upper layer. . When these plastic bands are used as a composite coating, as shown in FIG. 6, the lower plastic band 52 usually has a band width that is 1/2 of the width of the upper plastic band 53 minus the overlapping width 53a. As shown in FIG. Overlap allowance 5
3a is provided to form a half-overlap spiral to perform composite coating.

In this case, upper and lower two layers of plastic bands 53, 52
For example, as a method of extruding
One possible method is to extrude the lower and upper plastic bands separately from an extrusion die on a table and combine them on a metal tube, but this method requires a complicated structure for the extrusion die, and The operation of combining molten plastic strips on a metal tube is difficult and the work efficiency is poor, making this method impractical.

Therefore, a manufacturing apparatus shown in FIGS. 7 and 8 has been proposed. The structure of this manufacturing apparatus 60 includes a coat hanger manifold 63 for the upper plastic band in the same die body 61 for extrusion, and an extrusion width of about 1/2 of the manifold 63, and the coat hanger manifold 63 is placed unevenly in the die body 61. A coat hanger manifold 62 of a plastic band on the lower layer side is provided, and its lip opening 64 has a narrow and unevenly distributed upper layer lip opening 64a overlapping a flat upper layer lip opening 64b. It is shaped like this.

In this way, two types of semi-molten plastics having different physical properties are spread out from the coat hanger manifolds 62 and 63 respectively, and a composite plastic band 65 is extruded from the lip opening 64 as shown in FIG. According to the method, the composite coating is made such that the lower plastic strip 65a has a single-layer spiral shape, and the upper plastic strip 65b has a half-fold spiral shape.

[Problem that the invention attempts to solve]

By the way, in such a manufacturing apparatus 60,
Although it is easy to adjust the amount of extracted plastic that forms the upper and lower plastic bands 65a and 65b, since the lip opening 64 is asymmetrical and has an irregular shape, the plastic band 65 extruded under high pressure is There were problems in that it became distorted and irregularly shaped, making it impossible to perform a smooth coating operation, and also resulting in uneven coating thickness.

The present invention solves the above problems and provides a manufacturing device that is easy to operate and can perform smooth composite coatings of plastic strips.

[Means for solving problems]

This invention is equipped with a coat hanger manifold that spreads plastic in a strip shape inside the die body, extrudes the plastic strip from a flat lip formed at the tip of the die body, and coats the outer surface of the rotating metal tube with plastic in a spiral shape. In the apparatus for manufacturing coated metal tubes, a first coat hanger manifold spanning the entire width is provided in the main body, and a second coat hanger manifold narrower than the manifold and unevenly distributed within the main body. This is a manufacturing device for plastic-coated metal tubes.

[Effect]

The structure is as described above, and for example, a wide plastic band is extruded using the first coat hanger manifold as the upper layer, and a narrow plastic band is extruded using the second coat hanger manifold as the lower layer. A partially double layered overlapping plastic strip is extruded through the lip opening.

In this case, if the width of the lower layer manifold is approximately 1/2 of the width of the upper layer, and if it is unevenly distributed on either the left or right side of the die body, approximately half of the manifold on one side will contain two types of manifolds. A layer of plastic is formed, and the other side is formed with one type of plastic layer that is extruded only from the upper manifold.
A partially double-layered plastic strip having only one half layered is extruded from the lip opening.

In addition, since this lip opening is formed uniformly over the entire width, a plastic band with a uniform thickness in the width direction is extracted, and there is no distortion or irregular shape, allowing for smooth coating work. I can do it.

〔Example〕

An embodiment of the present invention will be described based on the drawings.

Fig. 1 is a partial cross-sectional plan view of a die body used in a composite cladding manufacturing device, Fig. 2 is a front view of the die body, and Fig. 3 is a sectional view taken along line A-A in Fig. 2. FIG. 4 is a sectional view taken along line BB in FIG. 2.

The die main body 1 is composed of an upper die 1a and a lower die 1b so as to be able to be divided into upper and lower parts approximately in the center, and a flat lip opening 2 is provided at the tip thereof in the horizontal direction. FIG. 5 is a longitudinally enlarged copy of the lip opening 2. The lip opening 2 has an even gap over the entire width of the die body 1, and both sides of the upper end are slightly tapered 2a in the diagonal direction. being done.

Inside the die body 1, there is a first coat hanger manifold 3 (hereinafter referred to as the first manifold) on the upper layer side that extrudes the plastic over the entire width of the lip opening 2, and a first coat hanger manifold 3 below it. A second coat hanger manifold 4 on the lower layer side (hereinafter referred to as the second manifold) having a width equal to approximately 1/2 of the length obtained by subtracting the overlapping allowance when covering a prescribed steel pipe from the width is placed inside the die body 2. The manifolds 3 and 4 are provided with T-shaped plastic inflow passages 3a and 4 in the center of each manifold 3 and 4, respectively.
4a is installed.

In general, the width of the second manifold 4 on the lower layer side is determined by the length obtained by subtracting the overlap allowance when covering the steel pipe from the first manifold 3 depending on the winding conditions of the plastic film during coating. The dimensions should be the same.

Reference numeral 6 denotes a choke bar, which is adjusted by an adjustment bolt 7 to adjust the thickness of the plastic 7 extruded from each manifold 3, 4. 8 again
is a fixing bolt for the lip hardware 9.

In this way, the plastic A having different physical properties is brought into a semi-molten state from the inlet channels 3a and 4a.
and plastic B are continuously press-fitted while maintaining a predetermined flow rate, these two types of plastics A and B will flow into the first and second manifolds 3 and 4.
As shown in FIG. 5, the plastic A extruded from the first manifold 3 on the upper layer side covers the entire width of the lip opening 2, and also extends over the entire width of the second manifold on the lower layer side. Plastic B extruded from the manifold 4 is unevenly distributed on one side of the lip opening 2 on the lower layer side of the plastic A, and is extruded from the lip opening 2 as a plastic band 10 having a partially two-layer structure.

Plastic strip 10 extruded in this way
As shown in FIG. 6, the lower plastic band 52 forms a single-layer spiral with respect to the metal tube 51 that rotates and moves in the tube axis direction, and the upper plastic band 53 forms a slight spiral. The composite coating is performed by providing an overlapping margin 53a to form a half-overlapping spiral shape.

In this embodiment, the shape of the lip opening 2 is tapered 2a on both sides of the upper end, so that the extruded plastic band 10 may have voids in the overlapping portion during coating. There are no bumps in the overlapped area, and smooth coating can be achieved.

[Effect of idea]

As explained above, the present invention has a pair of upper and lower first
Then, two types of plastics with different physical properties are pressed out from the second coat hanger manifold and formed into a band within the die body, and this is extruded from the flat lip opening to create a partially double-layered plastic with a uniform thickness. Therefore, the plastic strip does not become distorted or irregularly shaped, and it is possible to perform accurate and smooth composite coating with a single die, improving the efficiency of coating work and improving coating efficiency. It is possible to improve the quality of metal pipes.

[Brief explanation of drawings]

Figures 1 to 5 show an embodiment of the present invention, with Figure 1 being a partial cross-sectional plan view of the die body, and Figure 2 being a partially sectional plan view of the die body.
The figure is a front view of the die body, and Figure 3 is A- in Figure 2.
A sectional view, Fig. 4 is a BB sectional view of Fig. 2, Fig. 5
The figure is an enlarged copy of the lip opening, Figure 6 is a longitudinal sectional view showing a composite coating of a metal tube, Figures 7 to 9 are conventional examples, and Figure 7 is a side sectional view of the die body.
FIG. 8 is a front view of the die body, and FIG. 9 is a sectional view of the extracted plastic band. 1...Dice body, 1a...Upper die, 1b...
...Lower die, 2...Rip opening, 2a...Taper processing, 3, 4...Coat hanger manifold,
3a, 4a...Plastic inflow path, A, B...
...Plastic, 10,52,53...Plastic band, 51...Metal tube.

Claims (1)

[Scope of utility model registration request] A coat hanger manifold that spreads plastic into a strip inside the die body, extrudes the plastic strip from a flat lip formed at the tip of the die body, and coats the outer surface of the rotating metal tube with plastic in a spiral. A plastic manufacturing apparatus characterized in that a first coat hanger manifold spanning the entire width is provided within the main body, and a second coat hanger manifold narrower than the manifold and unevenly distributed within the main body. Coated metal pipe manufacturing equipment.