JP2005178020A - Coating forming method for coated metal pipe and coating forming apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating forming method for a coated metal pipe capable of generally simplifying an extrusion coating device, capable of increasing a manufacturing speed, capable of easily performing coating processing in the whole of a coating forming apparatus to generally make a product cost relatively inexpensive and enhancing the adhesion and bonding strength of the coating layer on the surface of a metal pipe to eliminate the occurrence of fear of peeling, and the coating forming apparatus therefor. <P>SOLUTION: At least a single resin layer is applied to the outer peripheral surface of the metal pipe by extrusion using a series of devices, which are composed of a feed roll device, at least one extrusion supply unit high frequency induction heating device connected to the die main body constituting the extrusion coating device, a press roll device, a cooler and a cutter all of which are successively arranged in the moving direction of the metal pipe of which the outer peripheral surface is preliminarily subjected to plating treatment, while moving the metal pipe in one direction. Further, the metal pipe is instantaneously heated to the melting temperature of the resin layer or above in cooperation with the movement of the metal pipe and the resin layer is pressed and closely bonded to the metal pipe as rapidly as possible before cooled and solidified. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In particular, the present invention provides a stepping stone (chipping) during traveling in a metal pipe having a relatively small diameter of about 20 mm or less, which is disposed as a brake pipe, a fuel pipe or other piping of an automobile or the like in a lower portion of a vehicle body. Alternatively, as a rust prevention measure against rainwater, muddy water (splash), etc., the present invention relates to a method for forming a coating of a coated metal tube in which a resin layer made of a resin layer is formed on its outer peripheral surface and a forming apparatus therefor.

  Conventionally, as this type of coating forming method and apparatus for forming such a coating, a long heat shrinkability made of a nylon resin, a vinyl chloride resin, a polyolefin resin or the like in advance on the outer peripheral surface of a metal tube generally having a plating film made of zinc or the like. A cylindrical member of material is deposited, and in this state, the heat-shrinkable resin is thermally contracted by passing the metal tube through a heating furnace under a reducing gas atmosphere, and then is cooled and solidified. In the case of a polymer coating by a method of forming a plurality of layers, a desired resin layer made of a different material is provided separately on the front and back of the die body that is provided separately from each other. The extrusion was carried out by a method in which the outer peripheral surface of the metal tube was extruded and polymerized by an extrusion supply unit, and then cooled and solidified to form a coating.

  However, in the conventional technique, the former is based on the use of a cylindrical member made of an expensive heat-shrinkable material, a long-time deposition work on a metal tube, and a reducing gas atmosphere as a heating device. Due to the necessity of the heating furnace and the reduction in processing efficiency due to low-speed passage through the reduction heating furnace, the production efficiency is poor and the product cost is inevitably increased. In the latter case, the die body provided separately before and after the extrusion coating apparatus, and an expensive suction mechanism and extrusion supply for connecting the extruded molten resin to the tube, which are connected to the die body. Depending on the structure of the unit, it depends entirely on the extrusion speed of the molten resin, so that the production efficiency cannot be increased at a pipe feed speed of 5 to 10 m / min, and the entire deposition apparatus is generally complicated and simple. In order to simply cool and solidify after coating, regardless of whether it is a layer or multiple layers, it is not possible to achieve sufficient adhesion and adhesion of the coating layer, especially on the surface of the metal tube. It had a problem that gave rise to.

  The present invention has been made in view of the above-mentioned problems of the prior art, makes the cylindrical member and its application work as in the prior art unnecessary, makes the extrusion coating apparatus generally simple, The manufacturing speed can be increased, and the coating process can be easily performed on the entire coating forming apparatus, so that the product cost can be relatively low as a whole, and the density of the coating layer on the surface of the metal tube can be reduced. It is an object of the present invention to provide a method for forming a coating of a coated metal tube and an apparatus for forming the same, which can strengthen the adhesion and the adhesion thereof and can eliminate the fear of peeling.

  In order to achieve the above object, the first embodiment of the present invention covers at least a single resin layer by extrusion molding on the outer peripheral surface while moving a metal tube whose outer peripheral surface is previously plated in one direction. In addition, in conjunction with the movement in the one direction, the metal tube is heated to a temperature higher than the melting temperature of the resin layer by high frequency induction heating, and then the resin layer is pressed from the outside by a press roll as quickly as possible. It is characterized by a method for forming a coating of a coated metal tube, which is bonded in a dense manner, and then the resin layer is cooled and solidified by passing through a cooling device.

  In addition, the second embodiment of the present invention is characterized in that at least one extrusion supply unit connected to a die body that sequentially forms a feed roll device and an extrusion coating device in a moving direction of a metal tube whose outer peripheral surface has been plated in advance. The present invention is characterized by a coated metal tube forming apparatus comprising a series of devices including a high-frequency induction heating device, a press roll device, and a cooling device.

The coated metal tube coating forming method and apparatus therefor according to the present invention include an extrusion supply unit (2 ₁ ) or / and (2 ₂ ) connected to a die body (2) constituting the extrusion coating apparatus, and a high-frequency induction. Due to the coating forming method in a series of devices with the heating device (3) and the subsequent press roll device (4), an expensive suction mechanism in the die body (2) is not required, and in the case of a single layer coating Eliminates the need for the bag member and its deposition work as in the prior art, and at the same time, the high-speed heating of the high-frequency induction heating device can increase the speed of extrusion molding, and can be extruded regardless of whether it is a single layer or multiple layers of polymer coating. The coating apparatus is generally simplified, and the coating process of the entire coating forming apparatus can be easily performed, so that the product cost can be relatively low, and the coating layer on the surface of the metal pipe (P) can be reduced. Many effects such as tightness and adhesion can be strengthened to eliminate the fear of peeling of the bent part of the product, and it can be adequately dealt with as anti-corrosion measures such as stepping stones and / or rainwater, muddy water, etc. Play.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a diagram of the whole of a single-layer coating according to a coating forming apparatus for a coated metal tube according to the present invention, and FIG. It is explanatory drawing equivalent to FIG. 1 at the time of the superposition | polymerization coating by the multilayer of the coating formation apparatus of another Example, (P) is a metal pipe which consists of a comparatively small diameter below about 20 mm in pipe diameter, Accordingly, the outer peripheral surface is subjected to a chromate treatment, for example, a corrosion-resistant plating treatment with zinc, nickel, aluminum, or a base alloy thereof.

In this state, the metal pipe (P) is moved in one direction, and a feed roll device (1) sequentially arranged in this direction, and an extrusion coating device for extruding resin on the outer peripheral surface of the metal pipe (P). A single extrusion supply unit (2 ₁ ) (see FIG. 1) or a plurality of extrusion supply units (2 ₁ ), (2 ₂ ) (see FIG. 2) connected to the die body (2) that does not require a suction mechanism. Although it is provided, the extrusion speed of the resin from the die main body can be increased according to this because the heating speed of the heating device is extremely high compared to the conventional one, as will be described later.

In the present invention, the following series of devices is further provided in the moving direction of the metal pipe (P).
That is, the high-frequency induction heating device (3) provided for heating the metal tube to a temperature higher than the melting temperature of the resin layer after coating the resin layer instantaneously heats the metal tube (P) to form at least the innermost layer of the resin layer. It is to be melted.

  Next, the press roll device (4) provided is a plurality of members that press the resin tube, at least the innermost layer of which is melted by heating the metal tube (P), over the entire circumference from the outside as quickly as possible. For example, it is composed of four grooved rolls, and the resin layer is firmly intimately bonded to the outer peripheral surface of the metal tube.

  Further, a cooling device (5) for effectively cooling and solidifying the coating layer is provided to perform forced cooling, and then a cutting device (6) for cutting the metal tube (P) to a regular size is provided. . With the series of devices described above, the metal tube (P) is fed, and the resin layer is coated, heated, pressed, cooled, and cut into a regular size to form a metal tube having a coating layer.

Note that the die body (2) has respective nozzle openings that are concentrically overlapped with each other in the extrusion supply units (2 ₁ ) and (2 ₂ ) and communicate with the defined flow gaps. In addition, (7) is a measurement roll provided on the downstream side of the cooling device (5) as necessary, and the resin-coated metal tube is placed in synchronization with the subsequent cutting device (6). It is provided for automatic regular cutting.

Next, the example is described in relation to the coating forming method of the present invention.
Example 1

Electrolytic bath temperature of 55 ° C, current density 60A / dm2 with a chromate treatment on the outer peripheral surface in advance, tube diameter of 8mm and wall thickness of 0.7mm by material SPCC plated with zinc of 25μm thickness with energization time of 2 minutes Extrusion from a die body with a continuous supply of extrusion supply units on the outer peripheral surface of a double-rolled metal tube, while the metal tube is moved at a feed rate of 20 to 40 m / min by a feed roll device. Thus, a polyamide resin (PA12) having a melting temperature of 190 ° C. was extruded to a layer thickness of about 0.9 mm to cover the resin layer. Next, in conjunction with the movement, the metal tube is instantaneously heated to a temperature of about 240 ° C. by a high-frequency induction heating device to melt the inner layer of the polyamide-based resin, and thereafter, a press roll comprising four rolls as quickly as possible. The outer peripheral surface of the resin layer was pressed from the outside over the entire circumference by means of an apparatus and adhered in an intimate manner to the outer peripheral surface of the metal tube to obtain a coating layer having a layer thickness of about 0.7 mm. Then, by continuously passing through a cooling device using circulating water, it was possible to obtain a coated metal tube having a coating layer that was forcibly cooled and solidified, then cut into a product length of 5 m and firmly adhered to the surface of the metal tube.
Example 2

  A metal tube having a 23 μm-thickness zinc plating film treated under the same conditions as in Example 1 on the outer peripheral surface of a double-rolled metal tube similar to Example 1, and the metal tube is fed at a feed rate of 20 by a feed roll device. Polyamide having a melting temperature of 180 ° C. by extrusion from the die main body supplied by an extrusion supply unit located at the rear of the die main body that is connected to the die main body forming the press coating device on the outer peripheral surface while moving forward at ˜40 m / min. The resin body (PA11) is extruded to coat a resin layer having a layer thickness of about 0.2 mm, and the die main body section communicating with the extrusion supply unit located on the front side formed in a separate body is almost synchronized with this. Polypropylene resin (PP) having a melting temperature of 170 ° C. by extrusion from a trapped nozzle port was extruded to form a polymer coating having a layer thickness of about 0.8 mm. Subsequently, instantaneous heating at a temperature of about 220 ° C. by a high-frequency induction heating device was performed continuously after the movement, and after that, pressing was carried out as quickly as possible by a press roll device similar to that of Example 1 to bond them in a dense form. A polymer coating layer having a layer thickness of about 1.0 mm was obtained. Then, it was cooled and solidified by passing through the same cooling device as in Example 1, and then a coated metal tube having a polymer coating layer firmly cut to a product length of 4 m and firmly adhered to the surface of the metal tube could be obtained.

  In the present invention, the extrusion coating apparatus is generally simplified, the speed of extrusion molding can be increased, and the coating processing in the entire coating forming apparatus can be easily performed, so that the product cost is relatively low as a whole. Furthermore, the coating of the coating layer on the surface of the metal tube and its adhesion are strengthened by instantaneous heating of the metal tube by the high frequency induction heating device after coating and subsequent pressing by the press roll device as quickly as possible. Therefore, it can be used as a rust prevention measure for flying stones and / or rainwater, muddy water, etc. This is extremely effective for forming coatings on various coated metal tubes having a resin layer formed thereon.

It is explanatory drawing which shows the whole at the time of the single | mono layer coating | cover concerning the coating formation apparatus of the covering metal tube of this invention in a diagram. It is explanatory drawing equivalent to FIG. 1 same as the above at the time of the superposition | polymerization coating by the multilayer of the coating formation apparatus of another Example.

Explanation of symbols

P Metal tube 1 Feed roll device 2 Die body 2 ₁ Extrusion supply unit 2 ₂ Extrusion supply unit 3 High frequency induction heating device 4 Presser roll device 5 Cooling device 6 Cutting device

Claims (2)

  While the outer peripheral surface is plated in one direction with a metal tube that has been plated in advance, the outer peripheral surface is coated with a resin layer consisting of at least a single layer by extrusion, and in addition to the movement in the one direction, high-frequency induction heating is performed. The metal tube is heated to a temperature equal to or higher than the melting temperature of the resin layer, and then the resin layer is pressed from the outside by a press roll as fast as possible to adhere in a dense manner, and then the resin layer is passed through a cooling device. A method for forming a coating of a coated metal tube, comprising cooling and solidifying a layer. At least one extrusion supply unit (2 ₁ ) connected in series to the die body (2) forming the feed roll device (1) and the extrusion coating device in the moving direction of the metal pipe (P) whose outer peripheral surface has been plated in advance. ), A high-frequency induction heating device (3), a press roll device (4), and a cooling device (5) are arranged to provide a series of devices.

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