JP2005178031A - Extrusion coating apparatus of resin coated metal pipe and method for forming resin coating layer on metal pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extrusion coating apparatus of a resin coated metal pipe for uniformizing the wall thickness of a coating layer due to extrusion coating and improving the adhesion thereof at the same time, and a method for forming a resin coating layer on a metal pipe. <P>SOLUTION: The extrusion coating apparatus of the resin coated metal pipe is composed of a guide core which is constituted so that the leading end part thereof is formed as a knife-like pointed end edge and a guide hole for the metal pipe moved to an axial center part is provided in a piercing state and has an outer peripheral surface expanded rearward from the pointed end edge, and a nozzle means, which is constituted so that the inner peripheral surface of the axial center thereof is coaxially providerd to a casing up to the nozzle orifice provided to the leading end of the nozzle means so as to hold a conical flow channel gap with the inclined surface of the guide core, and characterized in that the end edge part of the nozzle orifice almost coincides with the knife-like pointed end edge part of the guide core and is positioned in close vicinity to the outer peripheral surface of the metal pipe moved through the guide core. In the method for forming the resin coating layer on the metal pipe, the molten resin issued from the nozzle orifice is applied to the outer peripheral surface of the axially moved metal pipe as rapidly as possible. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is generally used in a metal pipe having a relatively small diameter of about 20 m / m or less that is disposed as a brake pipe, a fuel pipe or other pipe of an automobile or the like. A device for extrusion coating of a resin-coated metal tube that is coated with a resin with a thickness of about several tens of μm on its outer peripheral surface in order to have durability against splash and to have corrosion resistance, and formation of a resin coating layer on the metal tube Regarding the method.

  Conventionally, as an extrusion coating apparatus of this type, for example, as shown in FIG. 3, a round hole having an inner peripheral surface of a die (12) fixed to a casing (11) as a nozzle opening (12 ') at its tip. An inclined surface (12 ″) that extends rearward along with the wall (12 ″ ′) is formed, and a tip end portion is slightly flat end surface (13 ′) while holding a flow passage gap (15) inside the inclined surface (12 ″). And an inclined surface (13 ″) of the outer peripheral surface of the guide core body (13) penetrating a guide hole (13 ″ ′) for the metal tube (P ′) moving so as to cover the outer peripheral surface. It was set in a state of facing the inclined surface (12 ″). The tip portion forming the flat end surface (13 ′) of the guide core was connected to the round hole wall (12 on the die (12) side. ″ ′) And the inclined surface (12 ″) are positioned on the inner side. Core (13) forms a flat end surface of the distal end portion (13 ') is a spatial region of wedge present in the vicinity.

  However, in the prior art, the round hole wall (12 ″ ′) formed by the inner peripheral surface of the die (12), the inclined surface (12 ″) connected thereto, and the tip portion are slightly flat end surfaces ( 13 ′) and the guide core body 13 and the set state, the space region (near the flat end surface 13 ′) when the molten resin is coated on the outer peripheral surface of the metal tube (P ′). 14) due to the negative pressure state in this region due to the presence of 14) and the vibration caused by the forward movement of the metal pipe (P '), the coating layer is unevenly distributed, and the guide hole ( 13 ″ ′) had the problem of causing problems due to the penetration of the molten resin into the side.

  In order to prevent such a problem, a method of depositing the molten resin that has come out of the nozzle port in contact with the outer peripheral surface of the metal tube at a certain distance in the axial direction is conceivable. In this case, there is another problem that the adhesion with the outer peripheral surface of the metal tube deteriorates as a result because the inner peripheral surface of the molten resin coming out of the nozzle port comes into contact with the outer peripheral surface of the metal tube with some solidification. .

  The present invention has been made in view of the above-mentioned problems of the prior art, and by improving the mutual set structure in relation to the improvement of the shape of the die and the guide core body, the coating layer by extrusion coating can be improved. It is an object of the present invention to provide an apparatus for extrusion coating of a resin-coated metal tube and a method for forming a resin coating layer on the metal tube, which can make the wall thickness uniform and at the same time have good adhesion.

  In order to achieve the above object, a first embodiment of the present invention is such that a guide hole for a metal tube that moves a tip part to a knife-like pointed edge and a shaft core part is penetrated and expanded backward from the pointed edge. A guide core having an outer peripheral surface, and a nozzle provided coaxially in the casing while holding the inner peripheral surface of the shaft core up to the nozzle opening at the tip and holding the inclined surface of the guide core and a conical channel gap A resin-coated metal, wherein the edge formed by the nozzle opening is substantially coincident with the knife-shaped pointed edge of the guide core and is positioned close to the outer peripheral surface of the metal tube moving inside It features an apparatus for extrusion coating of tubes.

  Further, the second embodiment of the present invention is characterized by a method for forming a resin coating layer on a metal tube that coats the outer periphery of the metal tube moving in the axial direction as quickly as possible with the molten resin from the nozzle opening. It is what.

  Since the present invention is configured as described above, the inclined surface that expands the inner peripheral surface of the shaft core rearward to the nozzle port at the tip, the tip portion as a knife-like pointed edge, and the inclined surface A guide core body having an outer peripheral surface holding a conical channel gap, and a set that is positioned close to the outer peripheral surface of a metal tube that substantially coincides at the nozzle opening and the tip edge portion and moves inside the guide core body. The structure eliminates the concern of negative pressure by eliminating the presence of a space region at the tip of the guide core body, and at the same time effectively suppressing the vibration associated with the forward movement of the metal tube at the covering position. The thickness of the coating layer is made uniform, and the molten resin flowing out from the nozzle port is immediately deposited on the outer peripheral surface of the metal tube, so that the adhesion can be improved.

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 view with a partially cutaway cross section of a main portion showing an embodiment of an apparatus for extrusion coating of a resin-coated metal tube of the present invention. 2 is a view corresponding to FIG. 1 of another embodiment, and (1) is a casing constituting an extrusion coating apparatus, and a die (2) is attached to the front surface thereof by fastening means such as bolts as shown in FIG. Or a separate nozzle body (6) is further fixed to the front surface of the die (2) by a fastening means such as a bolt as shown in FIG. .
Then, the tip of the die (2) is used as a nozzle port (2 ') (see FIG. 1), or the tip of the nozzle body (6) is used as a nozzle port (6') (see FIG. 2) to form nozzle means. In addition, the inner peripheral surface of the shaft core is formed as an inclined surface (2 ″) that expands backward to the nozzle opening (2 ′) or (6 ′).

Further, (3) is a guide core body, which is an inner surface of the die (2) and has an inclined surface (3 ″) facing the inclined surface (2 ″) formed by the die (2). A molten resin flow passage gap (5) having a conical shape and positioned coaxially with the die (2) or the nozzle body (6), the tip of which is a knife-like sharp edge (3 ') and a guide hole (3 "') for a metal pipe (P) moved by a feed roller (not shown) is formed through the shaft core.
Then, the end (4) formed by the nozzle opening (2 ') or (6') substantially coincides with the knife-like pointed edge (3 ') of the guide core (3), and the moving metal tube ( P) is set in a state of being positioned close to the outer peripheral surface.

  Therefore, when the molten resin flows through the flow passage gap (5) and flows out of the nozzle port (2 ') or (6'), it immediately adheres to the outer peripheral surface of the moving metal tube (P). By effectively suppressing the vibration associated with the forward movement of the metal tube (P), the thickness of the coating layer can be made uniform and the adhesion can be improved.

  The apparatus for extrusion coating of a resin-coated metal tube and the method for forming a resin coating layer on the metal tube according to the present invention are free from the fear of a negative pressure occurring at the coating position, and effectively suppress the vibration caused by the movement of the metal tube. As a result, the thickness of the coating layer can be made uniform and the adhesion can be improved by quickly applying the molten resin flowing out of the nozzle port to the outer peripheral surface of the metal tube. The present invention can also be applied to extrusion coating and formation of resin coating layers on various metal tubes.

It is explanatory drawing by the partially notched cross section of the principal part which shows one Example of the apparatus for extrusion coating of the resin-coated metal pipe of this invention. FIG. 2 is a view corresponding to FIG. 1 showing another embodiment. It is a partially notched sectional view of an apparatus for extrusion coating of a resin-coated metal tube showing a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Die 2 'Nozzle port 2 "Inclined surface 3 Guide core body 3' Pointed edge 3" Inclined surface 3 "'Guide hole 4 End edge 5 Channel gap 6 Nozzle body 6' Nozzle port P Metal tube

Claims (2)

  A guide core body having an outer peripheral surface penetrating through a guide hole for a metal tube that moves the tip part to a knife-like pointed edge and a shaft axis part and extending rearwardly from the pointed edge to the tip nozzle opening The inner peripheral surface of the shaft core is composed of nozzle means provided coaxially in the casing while holding the inclined surface of the guide core body and the conical channel gap, and the edge formed by the nozzle port is the guide core. An apparatus for extrusion coating of a resin-coated metal tube, characterized in that the device is positioned close to an outer peripheral surface of a metal tube that substantially coincides with a knife-like pointed edge of the body and moves inside. A method for forming a resin coating layer on a metal tube, wherein the outer peripheral surface of the metal tube moving in the axial direction is coated with the molten resin that has exited the nozzle port as quickly as possible.

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