JP2002205329A - Method and apparatus for treating surface of synthetic resin pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for treating the surface of a synthetic resin pipe, capable of simply removing the flaw or streak formed to the surface of the pipe and capable of imparting gloss to the surface of the pipe. SOLUTION: The surface of the extrusion-molded synthetic resin pipe is treated with hot air having temperature higher than the melting temperature of the synthetic resin to temporarily melt the surface layer of the pipe to smooth the surface of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating a surface of a synthetic resin pipe, and more particularly to a method and an apparatus for treating a surface of a synthetic resin pipe for erasing minute irregularities such as scratches and streaks.

[0002]

2. Description of the Related Art Synthetic resin pipes are generally manufactured by extrusion using an extruder. In this extrusion process, the pipe surface is caused by contact with a calibration sleeve or the like. A fine line in the axial direction and fine scratches due to the pulling operation with the pulling machine occur, and the surface of the pipe becomes cloudy due to these fine scratches and fine irregularities like streaks, May be lost. Conventionally, the calibration sleeve and take-off machine were adjusted while the operation of the device was stopped so that these scratches and streaks did not occur.However, it is difficult to completely eliminate the scratches and streaks by these measures. In addition, there is a problem that it takes a lot of trouble.

Accordingly, an object of the present invention is to provide a surface treatment method and apparatus for a synthetic resin pipe which can easily remove scratches and streaks formed on the surface of the pipe and can provide a gloss to the surface of the pipe. And

[0004]

In order to achieve the above object, a surface treatment method for a synthetic resin pipe according to the present invention comprises irradiating the surface of an extruded synthetic resin pipe with hot air having a temperature not lower than the melting temperature of the synthetic resin. By temporarily melting the pipe surface layer and smoothing the pipe surface,
Particularly, the synthetic resin pipe is a polyethylene pipe or a polybutene pipe.

Further, the surface treatment apparatus for a synthetic resin pipe of the present invention is provided with a hot air irradiator for irradiating a hot air having a temperature equal to or higher than a melting temperature of the synthetic resin toward a surface of the extruded synthetic resin pipe. In particular, the hot air irradiating portion is formed in a ring shape arranged concentrically with the synthetic resin pipe.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a front view showing an example of an extrusion molding apparatus to which the present invention is applied, FIG. 2 is a perspective view showing an example of a hot air irradiation ring as a hot air irradiation section, and FIG. It is sectional drawing of the principal part of.

The extruder for extruding the synthetic resin pipe comprises an extruder 11, a die 12, a calibration sleeve 1
3. A cooling water tank 14, a take-off machine 15, and a cutting machine 16 are provided in the same manner as a normal extrusion molding apparatus.
A hot air irradiation ring 21 for performing a surface treatment of the synthetic resin pipe P is provided between the cutting machine 5 and the cutting machine 16.

That is, the synthetic resin pipe P extruded from the die 12 of the extruder 11 is taken up by the take-up machine 15 via the calibration sleeve 13 and the cooling water tank 14, and is subjected to surface treatment at the hot air irradiation ring 21. Then, the product is cut into a predetermined size by the cutting machine 16 to be a product.

A hot air irradiating section 21 which is a hot air irradiating section for irradiating hot air having a temperature not lower than the melting temperature of the synthetic resin forming the synthetic resin pipe P has an annular inner peripheral wall 22 and an outer peripheral wall 23 and both sides of both peripheral walls 22, 23. A pair of side walls 24 closing the edge,
A hot air supply pipe 26 for supplying hot air H into the hot air flow path 25 is provided on the outer peripheral wall 23 at a position concentric with the pipe P. Are provided on the inner peripheral wall 22, and a large number of ejection holes 27 for ejecting the hot air H supplied into the hot air flow path 25 toward the surface of the synthetic resin pipe P are provided.

The distance D between the inner peripheral wall 22 and the synthetic resin pipe P
Is set to several mm. If the distance D is too small, precise adjustment of the hot air irradiation ring 21 is required, and if the distance D is too wide, the ejection holes 27
The temperature of the hot air blown out from the heater drops, and the heating efficiency decreases.

The shape, position, and number of the ejection holes 27 may be set so that the hot air ejected from the ejection holes 27 spreads all over the pipe surface. For example, circular holes 27 having a diameter of 1 mm are arranged at intervals of 10 mm. I just need. In addition, the ejection hole 27 can be formed not only in a circular shape but also in a long hole shape.
A plurality of rows may be provided on the inner peripheral wall 22 or they may be arranged in a staggered manner. Furthermore, it is also possible to form a slit over the entire circumference of the inner peripheral wall 22.

The temperature of the hot air H applied to the pipe surface from the hot air irradiation ring 21 needs to be higher than the melting temperature of the synthetic resin forming the synthetic resin pipe P in order to temporarily melt a layer of several microns on the pipe surface. However, the maximum temperature is
It depends on conditions such as the contact time between the hot air and the synthetic resin. For example, when the contact time between the hot air and the synthetic resin is long, the pipe surface layer can be sufficiently melted even at a relatively low temperature. However, if the temperature of the hot air is too high, the molten synthetic resin may flow. Also, when the flow rate of the hot air is too large and the speed of the hot air blown to the pipe surface is too high, there is a possibility that the molten synthetic resin may have surface defects such as ripples. Further, when the temperature rises to the inner surface of the pipe, the final outer diameter may be reduced.

Therefore, the temperature and air volume (wind speed) of the hot air
Is appropriately set according to the type of the synthetic resin, the extrusion speed (moving speed) of the synthetic resin pipe P, the shape of the hot air irradiation ring 21, and the like. In general, if the extrusion speed of the synthetic resin pipe P is high, Hot air of relatively high temperature and high speed may be used, and if the extrusion speed is low, the temperature may be relatively low and low speed.

For example, when extruding a polyethylene pipe having an outer diameter of 216 mm (melting temperature: 120 ° C.) at a rate of 0.5 m / min, hot air of 350 ° C. is blown from the hot air irradiating ring 21 at a flow rate of 4.5 liters per second. , A few microns of the surface layer can be melted.

As described above, by irradiating hot air at a temperature higher than the melting temperature of the synthetic resin to temporarily melt the surface layer of the pipe, the resin in fine irregularities such as scratches and streaks is appropriately fused with the surrounding resin. The surface can be made smooth by smoothing the surface. Further, since it is only necessary to provide a hot air irradiating unit such as the hot air irradiating ring 21 and irradiate the hot air,
The equipment cost is also low, and it can be applied to existing extrusion equipment.

In this embodiment, the hot air irradiating ring 21 is incorporated into the extruder to perform the surface treatment simultaneously with the extrusion, thereby simplifying the process. In the step, hot air may be blown to the surface of the cut synthetic resin pipe.

Further, the hot air irradiating section for irradiating hot air to the pipe surface can perform the surface treatment only by passing the synthetic resin pipe through the ring by using the hot air irradiating ring 21 as described above. The surface treatment can be performed easily and reliably.However, the shape of the hot-air irradiating section is arbitrary. The hot air blowing part may be rotated around the synthetic resin pipe,
It is also possible to rotate the synthetic resin pipe with respect to more than one hot air irradiating section.

Further, as the hot air irradiating the surface of the synthetic resin pipe, it is preferable to use air heated by an electric heater or the like from the viewpoint of safety and cost. However, a flame of a gas burner or the like is directly applied to the surface of the pipe as hot air. It is also possible to mix the combustion gas of the burner and air to adjust the temperature, and then use it as hot air.

[0019]

As described above, according to the present invention,
Fine irregularities such as scratches and streaks on the surface of the synthetic resin pipe can be easily erased to give a gloss to the pipe surface.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of an extrusion molding apparatus to which the present invention is applied.

FIG. 2 is a perspective view showing an example of a hot air irradiating ring for irradiating hot air to a pipe surface.

FIG. 3 is a cross-sectional view of a main part of the hot air irradiation ring.

[Explanation of symbols]

Reference Signs List 11 extruder, 12 die, 13 calibration sleeve, 14 cooling water tank, 15 take-off machine, 16 cutting machine, 21 hot air irradiation ring, 22 inner wall, 23 outer wall, 24 side wall, 25 hot air flow path, 26 hot air supply pipe, 27 ejection hole, H hot air, P synthetic resin pipe

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F207 AA04 AA12 AG08 AK01 KA01 KA17 KK51 4F209 AA04 AA12 AG08 NK10 PA12 PB02 PC16 PG12 PJ09 PN03

Claims (3)

[Claims] The present invention is characterized in that the surface of an extruded synthetic resin pipe is irradiated with hot air at a temperature higher than the melting temperature of the synthetic resin to temporarily melt the pipe surface layer, thereby smoothing the pipe surface. Surface treatment method for synthetic resin pipes. 2. The surface treatment method for a synthetic resin pipe according to claim 1, wherein said synthetic resin pipe is a polyethylene pipe or a polybutene pipe. 3. A synthetic resin pipe surface treatment apparatus, comprising: a hot air irradiator for irradiating a hot air having a temperature equal to or higher than a melting temperature of the synthetic resin toward a surface of the extruded synthetic resin pipe.