JPH0117846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for integrally forming a flange portion on a heat-fusible fluororesin tube.

Copolymer of tetrafluoroethylene and hexafluoropropylene (FEP), copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (PFA)
Compared to other general-purpose plastics, heat-melting fluorocarbon resins have superior properties such as heat resistance, chemical resistance, and non-stick properties. is technically difficult.

Conventionally, transfer molding is known for molding heat-melting fluororesin pipes with flanges, but this method requires complicated molds, equipment, etc. to mold long dimensions. . Therefore, a method has been adopted in which a long dimension blank pipe is formed by extrusion molding, the openings at both ends of the blank pipe are heated, and the openings at both ends of the blank pipe are expanded to the outside diameter side using a T-shaped jig to form a flange part. ing. In this method, the flange portion is formed by heating the raw pipe, so when the pipe is used to transport high-temperature fluid, the flange portion tends to return to its original state due to heat. In addition, since the raw pipe of a certain thickness is expanded toward the outer diameter side, the thickness of the flange becomes thinner, which not only adversely affects the sealing properties but also makes cracks more likely to occur due to residual stress distortion during expansion. There were drawbacks such as:

In addition, to form a flanged fluorine resin pipe, a long straight pipe is butted or overlapped (wrapped) with a short flanged pipe, and the mating portion is
A method of heat bonding using PFA or the like is also known, but it has problems with work efficiency, bonding strength, and the occurrence of pinholes.

The purpose of the present invention is to solve the above-mentioned drawbacks, and the purpose of the present invention is to insert a fluorine resin tube into the gap between a splittable cylindrical mold and a core mold placed therein, and to While heating the cylindrical outer mold, the annular notch formed at one end of the large diameter part is filled with a melt of heat-melting fluororesin from the outside, and the melt is fused to the tip of the base pipe. This provides a method for integrally forming a flange portion on a blank pipe.

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a cylindrical outer diameter that can be divided into upper and lower halves, and a large-diameter portion 2 is formed at one end of the cylindrical cylinder on the outside, slightly closer to the center than the tip. The bottom surface of this large diameter portion 2 is horizontal to prevent the outer mold from rolling.

An annular flange forming notch 3 is formed in the center of the large diameter portion 2 from the inside in the radial direction, and a through hole 4 opens into the notch 3 from the outside of the large diameter portion 2.
to be drilled. 5 is an air vent hole communicating from the notch 3 to the outside of the large diameter portion 2.

Reference numeral 6 denotes a cylindrical core mold disposed within the outer mold 1, and the outer mold 1 and the core mold have a predetermined cylindrical gap through which the fluororesin tube A is inserted.

Insert the core mold 6 into the outer diameter 1, bring the tip of the core mold 6 into contact with the L-shaped part 7 formed at the tip of the outer mold 1, and pass the bolt 8 through the L-shaped part 7 to remove the core mold 6. The core mold is fixed within the outer mold 1 by screwing into the threaded portion at the tip. Reference numeral 9 denotes a hollow part within the core mold, into which cooling water is injected.

Numeral 10 is a pot installed outside the large diameter section 2 of the outer mold 1, and the lower end opening of the pot 10 communicates with the through hole 4 of the large diameter section.

This pot 10 is filled with a melt B of heat-melting fluororesin.

A plunger piston 11 is placed above the pot 10 and presses the melt B.

Numerals 12 and 13 are bolts screwed into the large diameter portion 2 of the outer mold 1, and are used to fix the outer mold 1 divided into upper and lower halves.

Next, a method for integrally forming the flange portion b on the fluororesin tube A using the above mold will be explained.

The fluorine resin tube A used in the present invention includes a tetrafluoroethylene resin, a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP). A long pipe is used that is formed from a fluorocarbon resin such as a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (PFA) or vinylidene fluoride resin (PVdF) using an extrusion method or the like. .

Further, as the material of the flange b formed at one end of the raw tube A, among fluororesins, heat-melting fluororesins such as the above-mentioned FEP, PFA, and PVdF, which can be turned into a melt by heating, are used.

First, the fluorine resin tube A is inserted into the gap between the outer mold 1 and the core mold 6, and the tip a of the tube A is brought into the annular notch 3.

Next, although the large diameter portion 2 of the outer mold is not shown, it is held in a hot press or a band heater is used to heat and melt the tip portion a of the raw tube. This heating temperature is higher than the melting temperature of the base tube A, which is 327℃ or higher for tetrafluoroethylene resin tubes, 280℃ or higher for FEP tubes, and 280℃ or higher for FEP tubes.
The temperature is 305℃ or higher for PFA tubes and 170℃ or higher for PVdF tubes.

In this state, the heated molten body B of the heat-melting fluororesin placed in the pot 10 is transferred to the plunger piston 11.
Hold the pot 10 and press it, passing it through the through hole 4 of the large diameter portion 2 from the opening at the lower end of the pot 10, and filling the annular notch 3.

Through this step, the heated molten material B fills the notch 3 and is fused to the heated tip a of the blank tube, so that the notch 3 forms a flange part b.

Note that when the heated melt B is filled into the notch 3, the air in the notch 3 is evacuated through the air vent hole 5.

Next, while pressing the plunger piston 11 in the pot 10, cooling water is injected into the hollow part 9 of the core mold to cool the tip part a and the flange part b of the raw pipe. Cooling water may be sprayed on the outside of the outer mold to enhance the cooling effect.

After cooling, the outer mold and the core mold are disassembled to obtain a tube in which a flange portion b is integrally formed at one end of a heat-fusible fluororesin tube A. In the same manner, a flange portion b is formed at the other end of the blank pipe A to complete the flanged straight pipe shown in FIG.

Fig. 4 shows a method in which a flange part b is formed at one end of a heat-fusible fluorocarbon resin tube A by the above method, cap nuts 14 and 15 are inserted into this, and a flange part b is similarly formed at the other end. , then a bellows-like unevenness 16 is formed on the raw pipe A.
This shows a flexible hose equipped with

As described above, in the present invention, the flange portion is formed by heating and melting the tip end of the fluorocarbon resin tube and supplying a molten body of heat-fusible fluorocarbon resin from the outside. It is simple and easy to manufacture.

Furthermore, unlike conventional methods, the flange portion is not formed by expanding the end of the raw pipe toward the outside diameter using heat, so the flange portion does not return to its original shape due to heat. do not have. Further, according to the present invention, the thickness of the flange can be appropriately set by changing the notch for forming the flange, so that the sealing characteristics of the flange can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the present invention. FIG. 2 is a side view of FIG. 1. FIG. 3 is a sectional view of a flanged straight pipe formed according to the present invention. FIG. 4 is a sectional view of a flexible hose molded according to the present invention.

Claims (1)

[Claims] 1. A large diameter part 2 is formed on the outside of one end of a splittable cylindrical outer mold 1, and an annular flange forming notch 3 is formed in the center of the large diameter part 2 from the inside in the outer radial direction. At the same time, a through hole 4 that opens into the notch 3 from the outside of the large diameter portion 2 is bored, and a cylindrical core mold 6 is placed within the outer diameter 1 with a gap between the outer diameter 1 and the core. Insert the fluorine resin tube A into the gap with the mold 6,
Bring the tip a of the raw tube A to the notch 3 of the outer mold,
While heating and melting the tip a of the blank tube A, the melt B of the heat-fusible fluororesin is filled into the notch 3 from the through hole 4, and the melt B is melted into the tip a of the blank tube A. A method for forming a flange portion on a fluorocarbon resin tube.