JP3052472B2 - Manufacturing method of electromagnetic flowmeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic pole structure of an electromagnetic flowmeter and a method of manufacturing the same, and is particularly suitable for an electromagnetic flowmeter having a small diameter.

[0002]

2. Description of the Related Art An electromagnetic flowmeter is a flowmeter to which Faraday's law of electromagnetic induction is applied, and has a structure in which an electromotive force generated by applying a magnetic field to a fluid is detected by a pair of electrodes. There are an excitation coil and a permanent magnet as a means for generating a magnetic field to be applied. In any case, it is desirable that the magnetic field can be concentrated at a necessary portion with high efficiency. To achieve this, it is necessary to minimize the gap distance between the magnetic poles. Ideally, the diameter of the normal cylindrical flow path through which the fluid flows and the distance between the magnetic poles should be the same, but in reality, the thickness of the wall of the non-magnetic measurement tube and the insulation covering the inner surface of the measurement tube A minimum of the thickness of the sex lining is added. Conventionally, it has been invented to reduce the gap distance between the magnetic poles by reducing the thickness of the tube wall of the measurement tube only in the magnetic path portion, and is exemplified in JP-A-2-156115 and JP-A-2-156116. ing.

[0003]

In the above prior art, there is a problem that the relative gap distance between the magnetic poles cannot be sufficiently reduced, particularly when the aperture is reduced, and the efficiency of the magnetic circuit is poor.

[0004] The purpose of the present invention is to provide a manufacturing method for realizing an electromagnetic flowmeter having a good magnetic circuit air gap distance is the short and efficiency between magnetic poles easily.

[0005]

Means for Solving the Problems The upper Symbol purpose is drilled a through hole perpendicular to the tube axis to the measuring tube of non-magnetic, there is inserted a rod of the magnetic material, the bonding is achieved by hollowing processing You.

[0006]

Since the magnetic pole is formed penetrating from the inner surface to the outer surface of the measuring tube, the magnetic pole becomes a part of the inner surface of the measuring tube, and the gap distance between the magnetic poles is the same as the inner diameter of the measuring tube. Since only the diameter of the road and the thickness of the insulating lining are used, a high-efficiency magnetic circuit with low magnetic resistance and low leakage magnetic flux is obtained.

[0007] The manufacturing method is only through-hole processing, insertion, joining, and hollowing along the inner periphery of the pipe, and does not require any special operation. Furthermore, in order to realize the sealing property of the flow path through which the fluid flows and the smoothness of the inner surface of the flow path by the insulating lining covering the inner circumference of the measurement tube, it is necessary to increase the processing accuracy in the through hole processing and the hollow processing. Absent. In addition, since the above-mentioned joining does not require a sealing function, the operation is simplified.

[0008]

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

FIG. 1 and FIG. 3 show an embodiment of the first invention. 1 is a stainless steel measuring tube, 2a and 2b are a pair of cylindrical iron poles made of silicon iron penetrating from the outer surface to the inner surface of the measuring tube, 3a and 3b are a pair of electrodes, and 4 is a pair of the measuring tube and the magnetic pole. A lining made of tetrafluoroethylene resin, which covers an inner surface and forms a flow passage of a fluid together with the electrodes;
5a and 5b are fillet welds between the measuring tube and the magnetic poles,
Reference numerals 6a and 6b denote magnetic cores that come into contact with the magnetic poles 2a and 2b to form a magnetic path, 7a and 7b denote coils that generate a magnetic field, and 8 denotes a main body. Here, the gap distance l ₁ between the magnetic poles is the sum of the diameter of the flow path and the thickness of the lining 4. On the other hand, in the conventional case, FIG.
As shown in the above, l ₂ is longer than l ₁ by the thickness of the measuring tube. In the present embodiment, the material of the measuring tube 1 is stainless steel, but other metals such as copper and aluminum or non-metals such as vinyl chloride may be used as long as they are non-magnetic. Further, the material of the magnetic poles 2a and 2b is made of silicon iron, but other magnetic materials such as electromagnetic stainless steel and permalloy may be used. In particular, in the case of electromagnetic stainless steel, welding to the measuring tube 1 is facilitated. Further, although the shapes of the magnetic poles 2a and 2b are cylindrical, the cross-sectional shape may be another shape such as a quadrangle or a triangle. The magnetic pole and the magnetic core may be formed as an integral part. Further, although the material of the lining 4 is tetrafluoroethylene resin, other insulating materials such as rubber may be used. The measuring tube 1 and the magnetic poles 2a,
The joining method of 2b is fillet welding, but since this joint does not require a sealing property, it may be spot welding or a method other than welding, such as adhesion. In this embodiment, since the magnetic pole is fixed to the measuring tube in advance, there is an effect that the magnetic pole does not shift when combined with the magnetic core.

FIG. 4 shows a manufacturing flow of one embodiment of the second invention. 1 is a non-magnetic measuring tube, 2 is a rod of magnetic material, 2
Reference numerals a and 2b denote magnetic poles, and reference numerals 5a and 5b denote joints between the measuring tube 1 and the rod 2 made of a magnetic material. First, a through hole is made in the measuring tube 1 perpendicular to the tube axis. Then, the rod 2 of the magnetic material is inserted into the hole. Here, the cross-sectional shapes of the through hole and the rod need to be the same, but a gap that does not hinder the joining in the next step is allowed. Next, the measuring tube 1 and the rod 2 of the magnetic material are joined on the outer surface of the measuring tube. This joining method can be applied to the present invention by any method, such as fillet welding, spot welding, oven brazing, brazing, bonding, and explosion, if only the strength requirement is satisfied. I do. Next, a magnetic rod 2 is cut out along the inner circumference of the measuring tube 1. Thereafter, the lining process and the electrode hole processing (not shown) are the same as in the conventional manufacturing method. In this embodiment, there is no need to process the rod of the magnetic material before insertion, and the rod can be used as it is, so that there is an effect that the production is easy.

FIG. 5 shows another embodiment of the second invention. An opening area differs between the outer surface side and the inner surface side of the measurement tube 1, and a through hole having a step in the middle thereof is vertically symmetrically formed. Then, rods 2a, 2 made of a magnetic material processed into the same shape as the upper and lower halves of the through hole.
Insert b. Subsequent joining and hollowing operations are the same as in the above-described embodiment. In this embodiment, there is an effect that a structure capable of generating a magnetic field having a high magnetic density by providing a magnetic pole with a diaphragm shape can be manufactured. The same effect can be achieved even if the shape of the through-hole and the rod of the magnetic material is tapered such that the opening area on the outer surface side of the measuring tube is large and the inner surface side is narrow.

[0012]

A first effect of the present invention is that a gap distance between magnetic poles is short and a high-efficiency electromagnetic flowmeter can be obtained. A second advantage is that an electromagnetic flowmeter having the above characteristics can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of the first invention.

FIG. 2 is a front view of a conventional example.

FIG. 3 is a side view of one embodiment of the first invention.

FIG. 4 is a manufacturing flowchart of one embodiment of the second invention.

FIG. 5 is a manufacturing flowchart of another embodiment of the second invention.

[Explanation of symbols]

 1 ... measuring tube, 2a, 2b ... magnetic pole, 4 ... lining.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-156116 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 1/58

Claims (3)

(57) [Claims] 1. A flow of fluid to be measured to the measuring tube of non-magnetic, the <br/> to generate a magnetic field you orthogonal to the tube axis of the measuring tube, the tube axis of the measuring <br/> Teikan and detecting an electromotive force in one pair of electrodes disposed opposite to a position perpendicular to the respective directions of the magnetic field generated
In the manufacturing method of the electromagnetic flowmeter to, opening the through-hole perpendicular to the tube axis in the measuring tube, insert a stick of magnetic material on the <br/> through hole, said magnetic material and said measuring tube method of manufacturing an electromagnetic flowmeter joining rod, and wherein said possible magnetic <br/> materials of rods unplug chestnuts in a cylindrical shape along the inner periphery of the measuring tube. 2. The cross-sectional shape of the through hole and the rod of the magnetic material according to claim 1 ,
Electromagnetic flow characterized by being either a square or a triangle
How to make a meter. 3. The method according to claim 1, wherein the rod of the magnetic material is joined to an outer surface of the measuring tube.
And a method for manufacturing an electromagnetic flowmeter.