JPH0718722B2 - Electromagnetic flowmeter detector and manufacturing method thereof - Google Patents

Description

The present invention relates to an electromagnetic flow meter, and more particularly to an electromagnetic flow meter detector in which a non-magnetic metal pipe is cast in a cast outer casing and its manufacture. Regarding the method.

(Prior Art) An electromagnetic flow meter detector in which a non-magnetic metal pipe is cast in an outer casing of a casting is, for example, filed by the applicant of the present application.
As disclosed in Japanese Utility Model Publication No. 58-87 published on January 5, 2013, it is not easy to tightly and firmly connect a non-magnetic metal pipe and a cast outer casing. And, Kimiko
In JP-A-58-87, both ends of a metal pipe are sharply formed and cast, so that the tip of the sharpened portion of the metal pipe is melted by the molten metal of the casting, and the welding to the casting outer casing is easier and easier. Measures are shown to be taken reliably. However, there is a problem that it cannot be said to be sufficient in terms of the yield of securing airtightness at the welded portion between the metal pipe and the cast outer casing.

(Problems to be Solved by the Invention) As described above, in the electromagnetic flowmeter detector in which the non-magnetic metal pipe is cast in the casting outer casing, the non-magnetic metal pipe is cast on the joint surface with the casting outer casing. There was a problem that the weldability did not reach a satisfactory level. Therefore, an object of the present invention is to provide an electromagnetic flowmeter detector with improved weldability and a method for manufacturing the same.

[Structure of Invention]

(Means for Solving the Problems) The electromagnetic flow meter detector of the present invention is such that the joint surface of the non-magnetic metal pipe with the casting outer casing is coated with a substance that facilitates welding with a previously melted casting, Before pouring the casting, the air in the mold is replaced with at least one of an inert gas and a reducing gas, or a non-magnetic metal pipe placed as a core in the mold when pouring the casting It is constructed such that it is surrounded by casting by adding a welding facilitating means such as vibrating with a sound wave.

(Operation) In the welding facilitating means applied to the electromagnetic flowmeter detector of the present invention, as a material for covering the joint surface of the non-magnetic metal pipe with the casting, the material having an antioxidant function and non-melting casting By using a metal that is easy to form an alloy with both the magnetic metal, oxidation of the joint surface is prevented, the wetness of the casting is improved with hot water, and welding is facilitated. Further, as a substance for coating the joint surface, a substance which has an antioxidant function and which is easily decomposed to form a metal alloy with both the molten casting and the non-magnetic metal (for example, platinum stearate, gold stearate). Etc.), the same effect can be obtained. Further, by substituting the air in the mold with an inert gas and a reducing gas before pouring, welding is facilitated by both functions of preventing oxidation of the joint surface of the metal pipe and reducing the remaining oxide. Furthermore, by ultrasonically vibrating the metal pipe when pouring the casting, the joint surface of the metal pipe becomes easier to wet with hot water, and if any oxide remains, melt it into the hot water. The effect is obtained and the welding is facilitated. The above-mentioned respective means for facilitating welding can be used not only individually but also in combination to further enhance the effect.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings of an example. 1 (a) and 1 (b) show an assembly of a non-magnetic metal pipe and a cast outer casing manufactured by the method for manufacturing an electromagnetic flowmeter detector according to an embodiment of the present invention. (1) is a non-magnetic metal pipe as a conduit of the electromagnetic flowmeter detector, and is made of a material such as austenitic stainless steel, bronze, or brass. (2)
Is a cast outer casing made of, for example, ductile cast iron.
The non-magnetic metal pipe (1) is placed in the mold as a core, and the casting surface of the metal pipe (1) with the outer casing (2) of the casting has a function of preventing oxidation and is melted in advance. (Hereinafter referred to as hot water) and a non-magnetic metal (for example, austenitic stainless steel, bronze, brass, etc.) that is the material of the metal pipe (1), and is a substance that is easily alloyed with a metal different from the base metal (for example, A pretreatment step of forming a coating (3) by depositing nickel, platinum, gold, silver, copper, etc.) by a means such as plating or vapor deposition is performed. A casting outer casing (2) was prepared by pouring molten metal into a mold incorporating the pretreated metal pipe (1) as a core.
And make an assembly of metal pipes (1).

The action and effect of the coating (3) in the casting process will be described below. If the coating (3) according to the present invention is not present, the metal pipe is welded where the hot water first touches, but the part away from the hot water is heated by the heat conduction of the pipe before the hot water is filled. The surface of the metal pipe (1) is oxidized. For example, an austenitic stainless pipe is an alloy of Ni, Cr and Fe, and Cr is oxidized to form Cr ₂ O ₃ on the surface. This Cr ₂ O ₃
Is a substance that has a remarkably higher melting point than stainless steel and is less likely to react with molten metal, so Cr ₂ O ₃ makes the metal pipe (1) less wet and less likely to cause welding.

When the coating (3) according to the invention is present, the metals forming the coating (3), namely Ni (melting point 1455 ° C), Pt (melting point)
When 1774 ℃, Au (melting point 1063 ℃), Ag (melting point 1980 ℃), Cu (melting point 1083 ℃), etc. come into contact with hot water, they melt at temperatures much lower than the melting point. Moreover, Ni, Pt, and Au maintain an excellent surface state without forming oxides until they are submerged in hot water. Ag and Cu react with oxygen in the air inside the hot mold
Although it becomes Ag ₂ O and Cu ₂ O, the effect of protecting the surface of the metal pipe (1) continues. Then, Ag ₂ O and Cu ₂ O submerged in the hot water react with C contained in the ductile cast iron, and become Ag, Cu and secondary metals such as Ag ₂ O + C = 2Ag + CO Cu ₂ O + C = 2Cu + CO. The produced product CO has a reducing property and has an effect of activating the surface of the metal pipe (1).

Coating with Ni, Pt, Au, Ag, Cu by the above action
By providing (3), the metal pipe (1) and the cast outer casing are
Welding with (2) is facilitated, and strong and airtight gluing is obtained with a high yield.

The shape of the joint surface (m) of the metal pipe (1) with the cast outer casing (2) is shown in FIGS. 2 (a), (b), (c), (d),
Various modifications can be made as shown in (e) and (f).

In addition, as a substance that forms the coating (3) on the joint surface (m), a metal that has an antioxidant function and that easily forms an alloy with both hot water and non-magnetic metal is generated by thermal decomposition at high temperature during pouring. As a result of thermal decomposition, the bonding surface (m) can be obtained by applying a substance such as platinum stearate or gold stearate to the bonding surface (m) of the metal pipe (1) in the pretreatment step. Platinum, gold, C, H ₂ are generated on the surface, and C, H ₂ reduces and activates the pipe surface, and platinum and gold improve the wetting, so that welding is facilitated.

Next, another embodiment of the method for manufacturing the electromagnetic flowmeter detector of the present invention will be described with reference to FIG. FIG. 3 shows an embodiment of a mold used in the process of casting a non-magnetic metal pipe in a cast outer casing. (11) is a core containing the non-magnetic metal pipe (1), and (12A), (12B), (12C), and (12D) are four-tiered sand molds. (13) is a sprue and (14) is a riser. Further, a gas inlet (16) reaching the bottom sand mold (12D) is provided.

As a means for facilitating welding, an inert gas such as Ar, He, N ₂ gas is made to flow into the mold from the gas inlet (16) before pouring to replace the air in the mold or to continuously pour. Purge for a while before pouring. By being in the atmosphere of the inert gas, the surface of the metal pipe (1) is not oxidized and the welding is facilitated.

Further, a reducing gas such as H ₂ or CO may be allowed to flow instead of the inert gas or mixed with the inert gas. In this case, it remains on the surface of the metal pipe (1). The metal oxide is reduced to activate the metal on the joint surface and facilitate welding.

Although the above-mentioned welding facilitating means alone is sufficiently effective, the above-mentioned welding facilitating means for providing a metal coating on the joint surfaces (m) and (m ') of the metal pipe (1) by pretreatment is also used. If so, the effect can be further enhanced.

Next, still another embodiment of the method for manufacturing the electromagnetic flowmeter detector of the present invention will be described with reference to FIG. Figure 4 is the third
The mold core (11) as shown in the figure shows a state in which the welding facilitating means of this embodiment is applied. That is, the core (11)
The ultrasonic oscillator (2
Allow ultrasonic waves to be applied from 1) via the ultrasonic transmission rod (22). Then, the pipe (1) is ultrasonically excited during pouring. The ultrasonic vibration makes the surface of the pipe easily wet, and strong vibration also has the effect of dissolving the oxide on the pipe surface into the hot water, facilitating the welding. This welding facilitating means is further effective if used in combination with pretreatment for forming a coating on the joint surface of the metal pipe, or both facilitating means for pretreatment for forming a coating and replacement with an inert gas in the mold. Is improved.

Further, in the core (11) shown in FIG. 3 and FIG. 4, the sand packed in the metal pipe (1) should be densely compressed and hardened, or hardened with resin, cement, water glass or the like. If so, there is an effect that the distortion of the pipe hardly occurs after the pouring.

Next, various aspects of the assembly of the non-magnetic metal pipe and the cast outer casing obtained by executing the above-mentioned welding facilitating means alone or in combination in the method for manufacturing an electromagnetic flowmeter detector of the present invention will be described. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, FIG.
Shown in Figure 10.

The one shown in FIG. 5 is a non-magnetic metal pipe (1) with a non-magnetic metal flange (31) attached by welding and a metal pipe.
An assembly in which (1) is cast in a magnetic cast outer casing (2).

The one shown in FIG. 6 is a non-magnetic metal pipe (1) encased in a magnetic casting outer casing (2) and at the same time a ready-made flange (non-magnetic or magnetic) (32) is held by a non-magnetic or magnetic casting flange. It is an assembly that is cast around the body (33). In the figure, a welding facilitating means is used for each joint surface (m), (n), (g).

What is shown in FIG. 7 is shown in FIGS. 1 (a), (b), FIG.
The assembly of FIG. 6 is for an electromagnetic flowmeter detector of the type equipped with a magnetic field generator having a solenoid coil, while the electromagnetic flowmeter detection of a type equipped with a magnetic field generator having a saddle coil Outer casing (34) which is a non-magnetic metal pipe (1) with flange for magnetic casting
It's a cast piece.

Fig. 8 shows an assembly in which the magnetic cast outer casing with the flange shown in Fig. 7 is replaced with a non-magnetic cast outer casing (35) and is easily welded to the joint surface (g). Use a means of conversion.
In this case, the magnetic core (3
6) Place.

What is shown in FIG. 9 is an existing magnetic flange (37) instead of the magnetic casting outer casing (34) with a flange shown in FIG.
And non-magnetic metal pulp (1) at the same time Magnetic cast outer casing (38)
It is an assembly that has been cast in. Welding facilitation means is used for each joint surface (m), (p).

Compared to Fig. 9, the one shown in Fig. 10 is a non-magnetic metal pipe.
It is an assembly in which both ends of (1) are positioned so as to be pulled inward from the position of the flange (37), and it is composed of an existing magnetic flange (37) and a magnetic cast outer casing (38). It is the same as the one in the figure.

In the assembly shown in FIG. 6, FIG. 9, and FIG. 10, a ready-made flange that has already been drilled is cast around, and the ready-made flange is inexpensive, and it is necessary to machine from the casting. Since it takes a lot of time to put it out, it is sufficiently advantageous to cast a processed ready-made flange.

〔The invention's effect〕

As described in detail above, according to the present invention, in the electromagnetic flowmeter detector in which the non-magnetic metal pipe is cast in the casting outer casing, the joining surface of the non-magnetic metal pipe and the casting outer casing is a molten product in advance. Cover with a substance that facilitates welding, replace the air in the mold with at least one of an inert gas and a reducing gas before pouring the casting, or By adding a welding facilitating means such as vibrating a non-magnetic metal pipe placed as a child with ultrasonic waves and casting it around, by performing each of the above means alone or in combination, The non-magnetic metal pipe and the outer casing of the cast metal work as a result of the functions of preventing the oxidation of the joint surface, improving the wetting of the joint surface by hot water, and reducing the oxides on the joint surface to activate them. Welding is facilitated and And airtightness good welding can be obtained in high yield. According to the manufacturing method of the present invention, the step of machining the casting outer casing for inserting and inserting the non-magnetic metal pipe into the casting outer casing can be eliminated, and the manufacturing cost can be reduced. In addition, since a strong and airtight weld can be obtained, a seal member between the pipe and the cast outer casing is not required. Further, since the joint surface is completely welded over the entire circumference, it is possible to obtain an electromagnetic flowmeter detector which is stable in both magnetic characteristics and electric characteristics.

[Brief description of drawings]

1 (a) and 1 (b) are cross-sectional views of a main part showing an assembly of a non-magnetic metal pipe and a cast outer casing, which are produced by a method for manufacturing an electromagnetic flowmeter detector according to an embodiment of the present invention, and FIG. (A),
(B), (c), (d), (e), and (f) are schematic views showing various examples of the shape of the joint surface between the non-magnetic metal pipe and the casting outer casing, and FIG. FIG. 4 is another embodiment of the present invention, which is a cross-sectional view showing the configuration of a mold used in the process of casting a non-magnetic metal pipe in a casting outer casing, and FIG. 4 is still another embodiment of the present invention. Cross-sectional view of a core adapted to shake, FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, FIG.
The drawings are cross-sectional views of main parts showing various aspects of an assembly of a non-magnetic metal pipe and a cast outer casing, which are manufactured by the method for manufacturing an electromagnetic flowmeter detector according to the present invention. 1 …… Non-magnetic metal pipe 2 …… Cast outer casing 3 …… Coating 11 …… Core 12A, 12B, 12C, 12D …… Sand mold 13 …… Gate, 14 …… Sticker 16 …… Gas inlet, 21 ... Ultrasonic oscillator 22 ... Ultrasonic transmission rod

Claims (7)

[Claims] 1. An electromagnetic flowmeter detector having a structure in which the conduit is made of a non-magnetic metal pipe, and the metal pipe is surrounded by a casting outer casing, wherein the metal pipe and the casting outer casing are outside the casting of the metal pipe. It is easy to make an alloy of both the cast metal that has been pre-deposited on the joint surface with the housing and has an anti-oxidation function and the non-magnetic metal of the metal pipe and the non-magnetic metal of the metal pipe. An electromagnetic flowmeter detector characterized by being welded in an airtight and strong manner by both actions. 2. A method of manufacturing an electromagnetic flow meter detector, comprising a non-magnetic metal pipe encased in a cast outer casing, wherein the joint surface of the metal pipe to the cast outer casing is easily wetted by the melted casting during casting. A method for manufacturing an electromagnetic flowmeter detector, characterized by adding a welding facilitating means that acts to ensure welding, and casting. 3. A pretreatment for forming a coating on the joining surface of a non-magnetic metal pipe with an outer casing of a casting by depositing a substance for facilitating the welding with a molten casting by plating, vapor deposition, or the like, by the welding facilitating means. The method of manufacturing an electromagnetic flowmeter detector according to claim 2, wherein the method is a process. 4. A substance which facilitates welding with a molten casting,
The method for producing an electromagnetic flowmeter detector according to claim 3, wherein the metal is a metal having an antioxidation function and capable of easily forming an alloy with both the molten casting and the nonmagnetic metal. 5. A substance which facilitates welding with a molten casting,
A metal compound having an antioxidant function, which is an organometallic compound which produces a metal which is easy to form an alloy with both a molten casting and a non-magnetic metal by thermal decomposition.
A method of manufacturing an electromagnetic flowmeter detector according to the item. 6. The welding facilitation means is a step of replacing the air in the mold with at least one of an inert gas and a reducing gas before pouring the casting. A method of manufacturing an electromagnetic flowmeter detector according to claim 2. 7. The welding facilitating means is to vibrate a non-magnetic metal pipe, which is placed as a core in a mold during pouring of a casting, by ultrasonic waves.
A method of manufacturing an electromagnetic flowmeter detector according to the item.