JPH05318554A - Production of surface roughened synthetic resin pipe - Google Patents

Abstract

PURPOSE:To prevent the generation of a crack, to hold mechanical strength and to easily control a roughness degree by rotating a roll having unevenness provided to the outer peripheral surface thereof in the peripheral direction thereof while bringing the same into contact with the outer surface of the tubular synthetic resin from the emitting port of an extruder. CONSTITUTION:A roll 6 having unevenness, for example, knurls or embosses provided to the outer peripheral surface thereof holds the gap corresponding to the thickness of a synthetic resin pipe with respect to the outer periphery of a core 4 and is arranged so as to be revolved in the peripheral direction of the core 4. The roll 6 having the uneven outer peripheral surface is rotated around its roll shaft 62 in the outer peripheral direction of the tubular synthetic resin from the emitting port of an extruder 1. The tubular synthetic resin moves in the longitudinal direction thereof during a period when the protruding parts of the roll 6 come into contact with the tubular synthetic resin and the surface thereof is scratched by the protruding parts of the roll 6 to form an uneven rough surface on the surface of the tubular synthetic resin. By controlling the rotational speed of the roll 6 having the uneven outer peripheral surface, a resin pipe different in surface roughness can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic resin pipe having a rough outer surface.

[0002]

2. Description of the Related Art There are various uses of synthetic resin pipes, and depending on the use, a low friction coefficient of the surface of the synthetic resin pipe may be an obstacle, and a synthetic resin pipe having a rough surface may be required. Examples thereof include an original pipe of a synthetic resin pipe with sand or a concrete body winding synthetic resin pipe used in the field of civil engineering and construction, a winding core, and the like.

Conventionally, to obtain a surface-roughened synthetic resin pipe,
Usually, the surface of the synthetic resin pipe is cut into a rough surface by a lathe or the like.

[0004]

The cutting mechanism of synthetic resin pipes is not as simple as that of wood. For example, when the cutting speed is low, the ductile fracture accompanied by viscous flow based on the stress relaxation phenomenon is the main, and when the cutting speed is fast, the brittle fracture is the main. When the temperature is high, ductile fracture is the main, and when the temperature is low, brittle fracture is the main.

As is clear from experience, when the chips are continuous, a smooth cutting surface can be formed, and when the chips are discontinuous, the cutting surface becomes rough. Thus, the roughening of the synthetic resin pipe by cutting is performed so that the chips are discontinuous, that is, under the condition that so-called chips are generated,
The cutting process under such conditions is mainly brittle fracture,
Many fine cracks occur on the cut surface.

Therefore, in the surface-roughened synthetic resin tube processed by the conventional method, a large number of fine cracks are present on the uneven rough surface, and depending on the usage conditions of the surface-roughened synthetic resin tube, the synthetic resin Early deterioration of the pipe is inevitable. For example, in the case of the above-mentioned concrete body-wrapped synthetic resin tube, the alkali-extracted portion of the concrete penetrates into the crystal structure of the synthetic resin through the cracks, and there is a concern that the synthetic resin tube may deteriorate early.

In the roughening process of the synthetic resin pipe, dust is remarkably generated, which causes a problem in working environment. Further, it is necessary to change the degree of roughness of the surface-roughened synthetic resin tube depending on the application, but it is difficult to adjust the degree of roughness by the above-described roughening processing method.

The object of the present invention is to produce a surface-roughened synthetic resin pipe which can prevent the generation of fine cracks well and can sufficiently maintain the mechanical strength of the synthetic resin and can easily adjust the roughness. To provide a method.

[0009]

The method for producing a surface-roughened synthetic resin pipe according to the present invention comprises a roll having irregularities on the outer peripheral surface,
The configuration is characterized in that the tubular synthetic resin is rotated in the circumferential direction while being in contact with the outer surface of the tubular synthetic resin from the discharge port of the extruder.

[0010]

The roughening process is performed immediately after the discharge port of the extruder, and since the synthetic resin is still in a thermoplastic state, the uneven surface can be formed on the synthetic resin pipe by plastic working. Further, by adjusting the rotational speed of the roll of the tubular synthetic resin in the circumferential direction, the uneven density of the surface of the synthetic resin tube can be adjusted to obtain a desired roughness.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory plan view showing an apparatus for manufacturing a surface-roughened synthetic resin pipe used in the present invention.

In FIG. 1, 1 is an extruder, 2 is an extrusion head, and 3 is a discharge port. Reference numeral 4 denotes a core, the core outer diameter of which is substantially equal to the inner diameter of the synthetic resin pipe to be manufactured, and the tip of the core shaft 41 is screwed to the end surface of the mandrel tip of the extrusion head 2. 5 is a cooling water tank. 6 is an unevenness on the outer peripheral surface, for example,
A roll having knurls, embossing, etc., which is installed so as to maintain a gap corresponding to the thickness of the synthetic resin pipe with respect to the outer circumference of the core 4 and to rotate in the circumferential direction of the core. .. For example, a gear (driven wheel) 61 is rotatably provided on the outer circumference of the extrusion head 2, a roll shaft 62 of the roll 6 is supported on the side surface of the gear 61, and a drive gear 63 is provided with a motor.
The shaft 64 is connected. 7 is a take-off machine.

According to the present invention, in order to produce a surface-roughened synthetic resin pipe, the synthetic resin is extruded from the discharge port 3 of the extruder 1 at a predetermined extrusion speed into a tubular shape, and the above-mentioned tubular synthetic resin is circumferentially stretched in the above-mentioned manner. The outer peripheral concavo-convex roll 6 is rotated at a predetermined speed to move the core 4
The tubular synthetic resin is run at a predetermined speed (extrusion speed) by the take-up machine 7 while supporting the inner surface of the tubular synthetic resin with the irregularities of the outer peripheral surface of the roll biting into the tubular synthetic resin surface. Let's pass through.

In this case, if the extrusion speed is V, the rotation angular velocity of the outer peripheral concave-convex roll 6 is η, and the outer diameter of the synthetic resin pipe is R,
In a spiral shape having a pitch angle θ that satisfies tan θ = ηR / V, the concave and convex marks of the roll 6 are formed on the surface of the synthetic resin pipe.

According to the present invention, the roughness of the surface-roughened synthetic resin pipe is determined by the number of irregularities per unit surface area,
Since the number of irregularities per unit surface area is determined by the density of irregularities on the outer peripheral surface of the roll and the spiral pitch, the surface roughened synthetic resin is changed by changing the rotational angular velocity η of the outer peripheral irregularity roll. It is possible to change the roughness of the tube.

In the above, when the outer peripheral surface irregularity roll 6 is rotated in the outer peripheral direction of the tubular synthetic resin, the outer peripheral surface irregularity roll 6 is rotated.
The roll 6 rotates (rotates) about the roll shaft 62. When the roll diameter is r and the tubular synthetic resin outer diameter is R, the rotation angular velocity ζ of this roll is ζ = ηR / r. Therefore, the width of the convex portion in the circumferential direction of the roll of the uneven surface of the outer peripheral surface is a
Then, the time t during which this convex portion contacts (cuts into) the tubular synthetic resin is t = a / (ζr). During this time, since the tubular synthetic resin moves by Vt in the length direction, the surface of the tubular synthetic resin is Vt [= aV / (rζ) = aV at one convex portion.
As the length of / (ηR) is scratched, the tube surface becomes uneven.

However, this scratching is performed while the resin immediately after the discharge port of the extruder is still in a sufficiently thermoplastic state, and moreover, the scratching amount is determined by the rotational speed η of the outer peripheral surface uneven roll and the like. By increasing the size, it can be made sufficiently small, so that the above-mentioned irregularities can be formed by deformation within the fracture limit of the thermoplastic deformation of the synthetic resin, and the fracture of the synthetic resin can be suppressed to obtain a surface-roughened synthetic resin pipe. ..

Incidentally, the outer diameter of the synthetic resin pipe R: 120 m
m, extrusion speed V: 90 mm / min, outer peripheral surface irregularity roll diameter r: 20 mm, rotational angular velocity η: 6 rp of the roll
When the m and the width a of the convex portion are 1 mm, the scratching amount per one convex portion is about 0.02 mm, which is very small and suppresses the fracture of the synthetic resin structure to make the surface-roughened synthetic resin. It is clear that a tube can be obtained. In this case, the height of the convex portion was 0.5 mm, the thickness of the outer peripheral surface uneven roll was 10 mm, the outer diameter of the core was 100 mm, and the gap between the core and the roll was 10 mm.

In the above, as shown in the figure, a plurality of outer peripheral surface concavo-convex rolls 6, ... Are arranged so as to be displaced in the length direction and the circumferential direction of the synthetic resin pipe, and a plurality of spiral miracles form a tubular shape. It is also possible to make the surface of the synthetic resin uneven.

[0020]

The method for producing a surface-roughened synthetic resin pipe of the present invention has the above-described structure, and the surface of the tubular synthetic resin from the discharge port of the extruder is deformed within the fracture limit of thermoplastic deformation. Can form irregularities, and a surface-roughened synthetic resin pipe without traces of resin breakage such as cracks on the surface can be easily manufactured. Further, the number of irregularities per unit surface area of the synthetic resin pipe can be adjusted by adjusting the rotation speed of the outer peripheral surface irregularity roll, and the roughness degree can be varied simply by changing the rotation speed of the roll. A variety of surface roughened synthetic resin tubes can be manufactured.
Further, since it is plastic working, there is an advantage that cutting waste is not generated and good working environment conditions can be maintained.

[Brief description of drawings]

FIG. 1 is an explanatory plan view showing a manufacturing apparatus used in the present invention.

FIG. 2 is an explanatory plan view showing another example of the disposition state of the outer peripheral surface roll used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 2 Extrusion head 3 Discharge port 4 Core 5 Cooling water tank 6 Outer peripheral surface roll 7 Take-off machine

Claims (1)

[Claims] 1. A surface roughness characterized in that a roll having irregularities on the outer peripheral surface is rotated in the circumferential direction of the tubular synthetic resin while being in contact with the outer surface of the tubular synthetic resin from the discharge port of the extruder. A method for manufacturing a flattened synthetic resin pipe.