JPS5947968B2 - Method for manufacturing a tube with electrodes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of attaching an electrode to a relatively small diameter tube, and more particularly to a method of manufacturing a tube applied to a small diameter electromagnetic flowmeter.

When manufacturing an electromagnetic flowmeter with a diameter of 15 mm or less, it is known that the electrode structure thereof is to form an electrode having a step shape that gradually tapers from the outside toward the inside.

Although this is one suitable structure for an electrode seal, it is fairly complex. In electromagnetic flowmeters with relatively large diameters, the head of the electrode, which has a larger diameter than the legs, is exposed inside the tube, and the legs are pulled outward and fixed to provide a seal. However, in the case of a small-diameter electromagnetic flowmeter as mentioned above, it is impossible to insert the electrode into its mounting hole from inside the pipe, so it is not possible to attach an electrode whose head has a larger diameter than the leg. However, the complicated electrode structure described above is inevitable. In view of the above, the present invention provides a method for attaching an electrode whose head portion has a larger diameter than the leg portion to a small-diameter tube in which the electrode cannot be inserted from inside the tube. Embodiments of the present invention will be described below with reference to the drawings. 1st
Figures A, , B, , C, and D show the manufacturing process of a tube with electrodes, and A shows a small-diameter heat-shrinkable electrically insulating tube 9. As such a tube, for example, a copolymer of tetrafluoroethylene and hexafluoropropylene (commonly known as FEP or Teflon 100) or vinyl chloride (commonly known as PVC) is used. A mold with an inner diameter larger than the outer diameter of the tube is placed on the outside of the tube, and air, water,
When a fluid such as oil is injected under pressure, the diameter of the tube increases as shown in FIG. 1B, and this state is maintained even when the pressure is removed. Of course, such an expansion step must be carried out at a suitable temperature, such as room temperature, at which the tube does not shrink. If rubber is used as the tube material,
A temperature of several tens of degrees below zero is applied to maintain the expanded state. The expanded tube 9' has a hole 10 formed on its diameter as shown in FIG. 1C.

The size of this hole is determined by the size of the head 11a of the electrode 11 to be attached.
Preferably, the size is such that it can be inserted from the outside. The head Ila of the electrode 11 has a larger diameter than the leg 11b. By heating and shrinking the tube with the electrode 11 inserted into the hole, the hole 10 also shrinks and comes into close contact with the leg portion 11b. Therefore, electrodes having heads having a larger diameter than the legs can be hermetically attached to the small diameter tube with the heads facing each other. In the above process, if the electrode leg portion 11b can be attached from inside the expanded tube, the size of the hole 10 may be made smaller than the size of the head portion 11a. In this case, the sealing effect is greater as the hole is smaller. Another step in the manufacturing method of the present invention is to make a hole sufficient to pass the electrode leg 11b in the tube shown in FIG. 1A, and expand the tube with this hole as shown in FIG. 1B. Figure 1C
．． ．． As shown in D, electrodes are attached and the tube is deflated. The same effect can be obtained even if the expansion step and the drilling step are reversed in this way. A tube with an electrode manufactured by the method of the present invention is made of a grain 12 cut vertically into two as shown in FIG.
, 12 from the outside to form a reinforced pipe, and by fixing the electrodes in a stretched state to the outside with springs 13, 13, a more reliable seal can be achieved.

Since the tube having electrodes manufactured according to the present invention has an electrode with a head whose diameter is larger than that of the legs, it has a simple structure similar to the electrode structure of a relatively large diameter electromagnetic flowmeter, and is also excellent. It has the advantage of providing a good sealing effect.

[Brief explanation of the drawing]

Figures 1A, B, C, and D are diagrams illustrating the steps of the method for manufacturing a tube with electrodes according to the present invention, and Figure 2 is a diagram showing a case where the tube manufactured by the method of the present invention is applied as an electromagnetic flowmeter. FIG. 9...Heat-shrinkable electrically insulating tube, 10
...hole, 11...electrode, 1Ia...
...head, 11b...legs.

Claims (1)

[Claims] 1. A step of expanding the diameter of a heat-shrinkable electrically insulating tube at an appropriate temperature at which no contraction occurs, and an electrode whose head portion has a larger diameter than its leg portion on the diameter of the expanded tube. a step of forming a hole large enough to insert the electrode into the hole, a step of inserting the electrode into the hole so that the electrode head faces the tube, and a step of applying heat to the tube with the electrode inserted to shrink the tube to close the hole. A method for manufacturing a tube having an electrode, the method comprising: bringing the electrode into close contact with the electrode. 2. Forming holes on the diameter of a heat-shrinkable electrically insulating tube that are sufficient to pass through the legs of an electrode whose head diameter is larger than the legs, and heating the diameter of the tube to an appropriate temperature that does not cause shrinkage. a step of inserting an electrode into the hole so that the electrode head faces the tube; and a step of applying heat to the tube with the electrode inserted to contract it and bringing the hole into close contact with the leg. A method for manufacturing a tube having an electrode.