JPH0478396A - Joint tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To joint a tube positively and prevent the generation of flow stop in a liquid passage by forming a thick wall part on the tube end side of a tube made of fluorine group resin, and heat-welding the tube ends of the thick wall part to each other. CONSTITUTION:In a joint tube, the tube end side of the tube 1 made of fluorine group resin is formed into a thick wall part 2 by hot working so as to be thick on the outer side. The tube ends of the thick wall part 2 are then heated to be softened, and the tube ends softened by heating are press-fixed and heat- welded to each other so as to attain the expected jointing. As a result, smooth welding can be performed, and rigid and complete jointing can be achieved. In addition, the flow stop of liquid in a liquid passage is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a joined pipe in which the ends of fluororesin pipes (tubes, pipes or hoses) are joined together, and a method for manufacturing such a joined pipe. Conventional technology Fluorine resin tubes have excellent heat resistance and corrosion resistance against chemical solutions, so they are used in the manufacturing process of semiconductors and other electronic components when ultra-high purity water and highly corrosive chemicals are used. It is widely used as a pipe material for sending liquids.

When installing pipes made of fluororesin pipes in a factory, 1. It is often necessary to join tubes together.

However, since it is extremely difficult to heat-seal the ends of fluororesin tubes, special measures are required to join the tubes.

For example, in Japanese Patent Application Laid-open No. 10378/1983,
The ends of the polytetrafluoroethylene resin tubes or rods to be joined to each other are inserted into the ends of the other tubes and fitted, and the fitting portion is made of polytetrafluoroethylene resin having an inner diameter slightly larger than the outer diameter. A method is adopted in which the fitting portion is heated to a temperature higher than the melting point by placing it in a cylinder made of a heat-resistant material whose expansion coefficient is smaller than that of fluoroethylene resin and heating the cylinder made of the heat-resistant material.

In Japanese Utility Model Application Publication No. 63-51992, a fluororesin tube with a funnel-shaped end is used as a coupling joint made of a cylindrical object made of polytetrafluoroethylene resin having a through hole and tapered ends. It adopts a structure in which it is fitted externally.

Problems to be Solved by the Invention However, the joining method described in JP-A No. 54-10378 does not allow the connection between the inner wall of the polytetrafluoroethylene resin tube on the insertion side and the tip of the polytetrafluoroethylene resin tube on the insertion side. Since a blind spot inevitably forms between the two, there is a fatal drawback in that when a liquid such as ultra-high purity water is passed through, stagnation occurs in the blind spot. In addition, since the tube on the inserted side and the tube on the insertion side are simply in close contact with each other, the gap between them is not strictly sealed, so the insertion depth must be long enough to prevent fluid leakage. However, the length of the tube of heat-resistant material provided on the outside of the fitting part must be sufficiently long, but if this is done, the joint will occupy a large proportion of the pipe, and it will also have a certain degree of flexibility. If flexibility is required, the flexibility of the joint portion will be compromised.

The coupling joint disclosed in Japanese Utility Model Application Publication No. 63-51992 also has a tube with an enlarged end fitted onto the coupling joint made of a cylindrical object, so a blind spot is created in the liquid path and stagnation occurs in that part. There are also disadvantages such as the liquid flow path becoming narrow at the joint and the possibility that the joint may come off if a strong tensile force is applied.

Various other joints for pipes made of fluororesin have been proposed, but they have similar drawbacks and problems such as overly complex structures.

In view of this situation, the present invention has developed a technology for joining fluororesin pipes that uses a simple mechanism that does not use joints, yet reliably joins the pipes and does not cause stagnation in the liquid path. The purpose is to provide the following.

Means for Solving the Problems The jointed pipe of the present invention is formed by forming a thick wall portion (2) so that the pipe end side of a pipe (1) made of a fluororesin is made thicker on the outside by heat processing, and The tube ends formed in the thick wall portion (2) are heat-sealed together.

In addition, the method for manufacturing a jointed pipe of the present invention includes a method for manufacturing a jointed pipe made of a fluororesin pipe (
Step A in which the tube end side of No. 11 is formed into a thick wall portion (2) by heat processing so as to have a thick wall on the outside; heating the tube end formed into the thick wall portion (2) in the previous step A; This method is characterized by comprising a step B of softening, and a step C of crimping and heat-sealing the tube ends that have been heated and softened in the previous step B.

The present invention will be explained in detail below.

The present invention relates to a technique for joining the tube ends of fluororesin tubes.

As a fluororesin, polytetrafluoroethylene (
PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PF
A), tetrafluoroethylene-ethylene copolymer (E
TFE), polytetrafluorochloroethylene (PCT)
Our fluororesin tubes, which include FE), polyvinylidene fluoride (PVDF), etc., are manufactured by sintering, extrusion, direct pressure molding, injection molding, transfer molding, etc. be done.

As shown in FIG. 1, the jointed pipe of the present invention is formed by heat processing so that the end side of a fluororesin pipe (1) becomes thicker on the outside so that it becomes a thick walled part (2). In addition, the ends of the tube formed in the thick portion (2) are heat-sealed to each other. In this case, it is desirable to maintain the inner diameter of the tube (1) as much as possible at the joint. In FIG. 1, (3) is the fused part.

This joint tube is typically manufactured according to Step A, Step B, and Step C described below.

Step A is a step in which the tube end side of the fluororesin tube ( ) is formed into a thick wall portion (2) by heat processing so as to have a thick wall on the outside.

One method for forming a thick-walled part (2) on the pipe end is to heat the pipe end of a fluororesin pipe (1) and then insert a conical part there, as shown in Figure 2 below. Press the shape widening jig (4) to widen the pipe end, then insert the convex part (5b) of the thick wall finishing jig (5) into the pipe (1). This method is to press the flat surface of the base (5a) of the jig (5) toward the tube end while maintaining the original inner diameter. This results in
A thick wall portion (2) is easily formed on the tube end side.

Another method is to form a thick wall part (2) on the tube end side.
As shown in Figure 3 below, insert a short fluororesin tube (la) that fits onto the end of the fluororesin tube (1), and then insert the tube (1). The end side is heated together with the short tube (1a), and then, while supporting the rear end side of the short tube (1a) with the holder (6), the thick-walled part forming jig (5) is placed inside the tube (1). This method involves inserting the protrusion (5b), maintaining the original inner diameter, and then pressing the flat surface of the base (5a) of the jig (5) toward the tube end. Also by this method, the thick interior (2) can be easily formed on the tube end side. This method is advantageous because it is easier to operate than the previously described methods.

In addition, since rapid cooling in the operation of step A may cause deterioration of the tube (1), the width expanding jig (4), the thick part finishing jig (5), and the holder (6) should be heated in advance. It's better to keep it.

Step B is a step of heating and softening the tube end formed in the thick wall portion (2) in the previous step A.

In this case, it is recommended that the tube ends be brought close to the panel heater (7) and heated in a non-contact manner, but heating in a contact condition or heating by other methods may also be adopted.

As the panel heater (7), a hot plate that emits far infrared rays, for example, is preferably used.

Step C is a step in which the ends of the tubes that have been heated and softened in the previous step B are pressed together and heat-sealed. This allows the desired bonding to be achieved.

Note that during the pressure bonding in step C, the softened resin may protrude and become flaky. To avoid this, a convex part (
5C) should be provided. In this way, process B
The above convex part (5C
) is formed, so that the softened resin retreats into the recess (2a) in step C, thereby preventing the occurrence of flakes.

Action and effect of the invention Pipe to be joined +11. (1) is both tubes (1),
Since the tube ends of the fil are all formed into thick-walled parts (2), smooth welding is possible even with tubes that are generally difficult to weld, such as tubes made of fluororesin. A strong and complete bond can be achieved. Since it is possible to maintain the original inner diameter during bonding, no liquid remains in the liquid path.

Therefore, it has extremely excellent performance as a conduit for transporting liquids such as solvents, acids, alkalis, etching solutions, ultra-high purity water, and cleaning solutions.

In this way, although the present invention employs a simple mechanism that does not use joints, it is possible to easily join fluororesin tubes without requiring special skill. This can be carried out not only at the pipe supplier's factory, but also at the site where piping, repair, or replacement is performed.

Example Next, the present invention will be further explained with reference to Examples.

Example 1 FIG. 1 is a cross-sectional view showing an example of a joint pipe of the present invention.

FIG. 2 is an explanatory diagram showing an example of the manufacturing process of the jointed pipe of the present invention.

Fluorine resin tube (1) - example outer diameter 17 mI
r1, polytetrafluoroethylene pipe with an inner diameter of 13 mm (
Prepare two tubes (1'1. f
The vicinity of the tube end of 1) was heated above its melting point (327° C.), and a heated conical widening jig (4) was pressed thereto to widen the tube end outward.

Next, using a thick part forming jig (5) having a shape in which a convex part (5b) having the same diameter as the inner diameter of the tube (1) protrudes from the disc-shaped base (5a), The heated jig (5) was pressed against the widened tube end. As a result, the tube end is melted and formed into a thick walled part (2), and
Tube (1) was able to maintain its original inner diameter of +11.

Next, the disk-shaped far-infrared radiation panel heater (7) is heated to about 500°C, and the above two tubes (11, +11 thick-walled parts (2) (2) are formed from both sides thereof. After placing the pipe ends close together and heating and melting only the surface of the thick-walled part (2), the panel heater (7) was removed and at the same time the thick-walled parts (2) and (2) of the pipe ends were crimped together. However, the thick portions (21, +21) were firmly fused to each other.

The welding condition of the fused portion (3) was extremely good, and the inner diameter of the welded portion maintained the inner diameter of the tube +1+.

Pipe after joining (one end of 11 is sealed, 50 kg/Cm"
A test was conducted in which pressure was applied, but no abnormalities were observed. Furthermore, the joint strength of the tube (1) was greater than the tensile strength of the tube +11 itself.

As the fluororesin tube (1), there are tubes made of tetrafluoroethylene-hexafluoropropylene copolymer, tubes made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and tubes made of tetrafluoroethylene-ethylene copolymer. When using a tube, a tube made of polytetrafluorochloroethylene, and a tube made of polyvinylidene fluoride, the bonding could be performed smoothly in the same way.

Embodiment 2 FIG. 3 is an explanatory diagram showing another example of the manufacturing process of the joint pipe of the present invention.

Two tubes (1) made of fluororesin from Example 1 are prepared, and a short tube (l) made of fluororesin is attached to the end side of each tube (1).
a) was fitted externally.

An example in which the tube end side of each tube (1) is heated together with the short tube (la), and then the rear end side of the short tube (1a) is supported by the holder (6) and preheated inside the tube (11). Insert the convex part (5b) of the thick-walled part forming jig (5) having the same shape as 1, maintain the original inner diameter, and then insert the protrusion (5b) of the jig (5) toward the tube end.
5a) was pressed against the flat surface. This results in
The tube end is melted and formed into a thick walled portion (2), and the tube f
2), the original inner diameter of fl) could be maintained.

Next, the disk-shaped far-infrared radiation panel heater (7) is heated to about 500°C, and the thick-walled parts (2) of the two pipes fl) and fl) are heated from both sides thereof.

After placing the tube ends formed in (2) close together and heating and melting only the surface of the thick wall portion (2), the panel heater (7) is removed and at the same time the thick wall portion f2) of the tube ends, (2) When the thick parts f2) and +2) were crimped together, the thick parts f2) and +2) were firmly fused to each other.

Embodiment 3 FIG. 4 is an explanatory diagram showing still another example of the manufacturing process of the jointed pipe of the present invention.

A disk-shaped base (5a) is used as the thick-walled part forming jig (5).
Example except that a convex part (5b) having the same diameter as the inner diameter of the hollow tube (1) protrudes, and a convex part (5c) is provided on the flat surface of the base part (5a). 2 was repeated. No paris was observed in the resulting joint tube.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a joint pipe of the present invention. FIG. 2 is an explanatory diagram showing an example of the manufacturing process of the jointed pipe of the present invention. FIG. 3 is an explanatory diagram showing another example of the manufacturing process of the joint pipe of the present invention. FIG. 4 is an explanatory diagram showing still another example of the manufacturing process of the joint pipe of the present invention. (1)...Fluororesin tube, (la)...Short pipe, (2)...Thick walled part, (2a)...Concave part, (3)...
・Fusion part, (4)...Jig for widening, (5)...Jig for forming thick part, Sal...Base, (5b)...Protrusion, (5C)
... Convex portion, (6) ... Holder (7) ... Panel heater patent applicant Yodogawa Kasei Co., Ltd. Figure a

Claims (1)

[Claims] 1. The tube end side of the fluororesin tube (1) is formed into a thick wall portion (2) by heat processing so as to have a thick wall outward. ) A jointed pipe whose ends are heat-sealed together. 2. Process A in which the tube end side of the fluororesin tube (1) is formed into a thick wall part (2) by heat processing so as to have a thick wall on the outside; pre-process A to form the thick wall part (2); A method for manufacturing a jointed pipe characterized by comprising a step B in which the formed tube ends are heated and softened, and a step C in which the tube ends heated and softened in the previous step B are crimped and heat-sealed. .