JP2001321951A - Joining device of metal and method of joining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of joining and a device by which a metal is safely joined in a short time with a high quality at a construction site or the like. SOLUTION: The metal material is joined in a way that ring cores 4 on which a primary coil 5 is wound are provided at the outer side of the metal faces to be joined, electrodes 8 and 9 are arranged on both sides of the faces to be joined, both electrodes 8 and 9 are short-circuited with conductive members 10 and 11 which pass around the outer sides of the ring cores 4, and the faces to be joined are heated by energizing the primary coil while the faces to be joined of the metals 1 and 2 to be joined are pressurized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact metal joining apparatus capable of continuously and efficiently joining pipes, shaped steels, and the like without deterioration in strength even in a poor environment such as a construction site.

[0002]

2. Description of the Related Art Conventionally, metal joining has been performed on a large scale in a wide range, including welding, on a daily basis since it is the basis of a structure. Recently, large pipes such as piles, waterways, and oil well pipes are buried deep in the soil.

However, in the case of a metal to be buried, for example, a large-diameter pipe, there are problems that it takes too much time to weld the entire circumference and that welding defects tend to occur.

[0004] In order to solve these problems, various methods for joining metals in a short time by electricity have been proposed. For example, it has been proposed to employ electric heating. For example, Japanese Patent Application Laid-Open No. 610067/1994 describes that power is supplied from both ends of the coil, and Japanese Patent Application Laid-Open No. 5171259 describes that power is supplied directly to the inside and outside electrodes having an expansion / contraction mechanism. As a method of heating using electricity, Japanese Patent Application Laid-Open No. 6119097 describes a method of passing an iron core through a coil and performing induction heating.

[0005]

However, in the direct heating method, a large current is required because the resistance between the electrodes is small, and the cable to the electrodes must be thick. In addition, thick cables must be routed endlessly in order to use them at construction sites, and resistance loss cannot be avoided. In addition, since stray current is transmitted through the metal due to the electrode potential, there is a problem that a safety problem occurs, and a current does not effectively flow through the joint.

In addition, in the case of induction heating, the magnetic flux leaks easily and it is difficult to carry out efficient heating, and the heating range is widened to heat an unnecessary portion. Is heated. In addition, since heat is generated only up to the depth of penetration, the temperature distribution is easy to occur.Even when pipe-shaped metal is placed on a ring-shaped induction coil and heated, the distance between the induction coil and the material to be heated is almost equal. If not, there is a problem that heat is easily generated. In addition, there are various obstacles when working on a construction site, such as a high coil voltage and the need to place a matching device near the material to be heated.

Accordingly, an object of the present invention is to provide a compact joining apparatus capable of joining metals safely and with good quality even at a construction site.

[0008]

Means for Solving the Problems (1) A good magnetic ring core in which a primary coil is wound so as to surround a metal end face to be joined by pressing and abutting, and has a cooling function on both sides of the joining surface. A metal bonding apparatus comprising: an electrode; and a secondary circuit formed by short-circuiting between the electrodes with a conductive member passing outside the good magnetic ring core.

(2) Using the joining device described in (1) above,
This is a method of joining metals, in which a current is passed through a primary coil to heat and join a metal joining surface between both electrodes.

(3) An insert material is sandwiched between metals to be joined by using the joining device according to (1),
(2) The method for joining metals according to (2), wherein the joining is performed by melting and diffusing the insert material.

(4) By controlling the distance between the cooling electrode and the bonding surface and the cooling ability of the electrode, the bonding is performed while controlling the range in which the temperature of the bonding metal becomes high due to current generation. Or a method of joining metals according to (3).

(5) One metal is buried in the ground, and the electrode in contact with the metal on the side opposite to the side buried in the ground is grounded.
The metal bonding method according to any one of the above (2) to (4), wherein the bonding surface is bonded by heating.

[0013]

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

FIG. 1 is a schematic sectional view for explaining a metal joining apparatus according to the present invention, showing a state in which an insert material is inserted between metals to be joined and one end of the metal is buried in the soil.

Although not shown, a force is applied to the metal 2 to apply a pressure to the joining surface with the insert material 3 interposed between the joining surfaces of the metal 1 and the metal 2 to be joined. Both metals 1,
A ring core 4 is arranged on the outer periphery of the ring 2 so as to surround the joining surface. A primary coil 5 is wound around the ring core 4 and connected to a primary power source 7 via a power cable 6. The primary coil may be a water-cooled copper pipe or the like, and its surface may be insulated to prevent a short circuit accident. In FIG. 1, the primary coil 5 is wound only on the upper side, but the primary coil 5 may be wound on the ring core 4 with a required number of turns including the lower part.
When the load greatly changes, it is preferable to tap the middle of the primary coil 5 and appropriately select the number of turns. The shape of the ring core 4 may be rectangular or cylindrical depending on the material. The material may be a good magnetic material, such as an electromagnetic steel sheet, a ferrite core, or an amorphous material.

Electrodes 8 and 9 are provided on both sides of the surface of metal 1 and metal 2 to be joined, respectively, and short-circuited by conductive members 10 and 11 which are turned outside ring core 4. When a voltage is applied from the primary power supply 7 to the primary coil 5 in this state, a secondary voltage is induced in the metal 1, metal 2, and the insert 3 in the ring core 4. The induced secondary voltage forms a secondary circuit by short-circuiting the electrodes 8 and 9, and a secondary current flows from the electrodes 8 and 9 to the junction surface between the metal 1 and the metal 2,
Heating is performed. That is, the metal in the ring core 4 is a transformer whose secondary winding is 1T, the number of turns of the primary coil is n1, the primary voltage is V1, the primary current is I1, the secondary voltage is V2, and the secondary current is I2. Then the approximate secondary voltage,
The secondary current is represented by equations (1) and (2).

[0017]

(Equation 1)

[0018]

(Equation 2)

Therefore, in this method, electric power can be supplied from the primary power supply 7 at a high voltage and a low current through the power supply cable. Therefore, equipment such as a matching panel, which is necessary for the induction heating device, is not required around the place to be joined. Power transmission with less cable loss is possible. Moreover, since the ring core 4 having excellent magnetic properties is used, heating with high conversion efficiency can be performed without a problem of magnetic flux leakage. At this time, the secondary voltage V2 generated between the electrodes is used for a potential drop due to heat generated by the secondary current I2, so that the electrode potential becomes extremely small. That is, assuming that the resistance including the insert material between the electrodes is R, and the combined resistance of the conductive members 10 and 11 is r, the electrode potential E can be roughly obtained by the equation (3).

[0020]

(Equation 3)

Accordingly, if the resistance of the conductive members 10 and 11 is reduced, the electrode potential E can be reduced. For example,
If copper is used as the conductive member, the resistance can be easily reduced to mΩ or less. Therefore, even if the secondary current is on the order of 10 3, the electrode potential can be reduced to 1V or less. It is an extremely safe facility with low risk. Furthermore, if one of the electrodes is grounded as shown in FIG. 1, the potential of the electrode on the ground side can be set to 0, and equipment trouble due to stray current can be avoided. Therefore, for example, when burying a metal joined like a pile in the ground, the metal on the opposite side to the buried metal is likely to have a device for applying pressure or to be touched by humans. If the opposite electrode is grounded, the voltage will not be applied and you can work safely. In FIG. 1, metal 1 is underground 12
When the electrode 9 in contact with the metal 2 is grounded via the conductive member 11, no current flows on the metal 2 side. On the other hand, on the metal 1 side, even if a current flows, it flows into the underground 12, so that no equipment trouble occurs. However, when the potential of the electrode 8 increases in FIG.
It is preferable to provide a choke core 13 between the underground 12 and the electrode 8 to reduce the current flowing underground.

The contact surface heated in this way becomes a uniform joint surface by being pressurized.

In the present invention, by further cooling the electrode, it is possible to locally limit the heating range. In other words, the “high temperature range” described in claim 4 is, as shown in FIG. 2, centering on the joining surface except for the vicinity of the cooled and low temperature electrode between the cooled electrodes 8 and 9. Refers to the high-temperature portion that has been heated. Therefore, the portion other than the joining surface is not heated unnecessarily, and the strength is not reduced.
Bonding with a minimum heat affected range is possible. When it is necessary to rapidly cool the joint immediately after heating, this can be realized by enhancing the cooling of the electrode as it is or by bringing the electrode itself closer to the joint. Particularly, as an insert material, for example, Japanese Patent Application No. 10-1197
No. 42, a component-based metal is generally a metal having a large specific resistance and a relatively low melting point, so that it easily generates heat and melts. When the electric heating is performed as described above, only the vicinity of the bonding surface rapidly rises in temperature, and the bonding can be performed while minimizing the influence of heat on other parts.

For the electrode, the base material is made of copper or an alloy thereof having excellent electrical and thermal conductivity, and is sprayed with a hard metal, ceramics or cermet for imparting abrasion resistance and welding resistance to the surface layer. It may be made of carbon or a carbon-based material mainly composed of carbon or carbon fiber which has good heat conductivity because it can improve the contact with the metal to be welded and prevent welding. In order to cool the electrode, the electrode may be manufactured from these materials, and a cooling path for passing a coolant such as water may be provided inside or outside, or a transport device such as a heat pipe may be provided. The shape of the electrode may be, for example, a shape that matches the shape of the metal to be heated. If necessary, the electrode may be divided and pressed.

As described above, according to the joining apparatus and the joining method of the present invention, the equipment can be made compact, and high-quality joining can be performed safely even at a construction site.

Hereinafter, embodiments of the present invention will be described.

[0027]

EXAMPLE In order to verify the effectiveness of the present invention, an experiment was conducted in which cylindrical iron was joined.

The metal material used in the experiment has a diameter of 50 mm,
Two round bars of 200mm long carbon steel (SS400), 13% B, 8% Si, V
Is 1%, and an iron-based amorphous foil (thickness: 25 μm, melting point: 1100 ° C.) having an unavoidable component in the remainder is used.
The ring core is a laminated electromagnetic steel core having a cylindrical shape with an inner diameter of 20 cm, an outer diameter of 25 cm, and a width of 3 cm.
A copper pipe of 20 mm wound with 20T was used. The power supply
A thyristor power supply with a frequency of 50 Hz, a voltage of 200 V, and 1000 A was used. Bonding was performed by sandwiching two inserts between the tip and both round bars whose electrode contact portions were polished, and applying current while applying a pressure of 5 MPa from both ends of the round bar. The electrode was fixed to a round bar with bolts at a position 50 mm apart from the joint surface, a half-width copper electrode having a width of 20 mm and a thickness of 10 mm obtained by brazing a water-cooled copper pipe to the surface. The electrode was provided with six terminals in the circumferential direction, both electrodes were short-circuited with a 100 mm ² cable, and the electrode in contact with the metal opposite to the side buried in the ground was grounded. In this state, the primary power supply is energized, a secondary current of 4000 A is applied, and the joint is 12
Heated to 00 ° C and held for 5 minutes. After cooling, the strength of the joint surface was compared with the base metal strength. As a result, it was confirmed that the strength of the joined portion was 0.99 times the base material strength and hardly deteriorated. As a comparative example, a frequency of 1000 Hz,
An experiment was conducted using the same metal material, insert material, and pressure as in the example except that induction heating was performed with a heating coil width of 40 mm. As a result, the strength of the joined portion was reduced to 0.7 times the strength of the base material. In this experiment, the range of the high-temperature portion during the heating was about 10 mm in width around the joint surface, whereas the heating width was as wide as about 80 mm in the induction heating, and a decrease in the strength of the base material was inevitable.

[0029]

According to the present invention, a matching plate such as induction heating is not required, and even if a metal material has a large joint surface,
Since it is only necessary to provide a ring core and an electrode having a relatively small cross section, it is possible to perform joining with extremely compact equipment.

Even if a large amount of power is applied, the voltage generated near the junction decreases due to internal consumption, so that the voltage appearing at the electrode is extremely small. No current flows to the machine or the side touched by humans, enabling safe work.Even in a work place where metal is driven into the ground, such as a pile, the electrode side opposite to the ground side is Extremely safe work is possible by driving into the ground.

Also, unlike the conventional method such as welding,
Since a large amount of electric power can be forcibly applied to the joint, the time for raising the temperature is extremely short, and the working time can be greatly reduced.

In the present invention, by using the principle of the transformer, electric power can be brought to the junction site with high voltage and low current, so that the power transmission loss is small. Furthermore, since a core with good magnetic properties is used, the leakage magnetic flux is extremely small,
Extremely high energy conversion efficiency. The fact that the leakage magnetic flux is small also has an effect of preventing an accident of heating another metal near the joint.

Regarding the uniformity of the temperature distribution which is the most important in the joining, the induction heating is easily affected by the distance between the induction coil and the object to be heated, and in principle, the depth of the induced current is deep. Temperature distribution is easy to get
According to the method of the present invention, if the metal material to be joined interlinks with the magnetic flux passing through the ring core, the current flows evenly in the joining cross section, so that the temperature distribution of the joining portion is hardly attached and the quality is good. Enables heating. Furthermore, in this bonding method, it is possible to limit the location where the temperature becomes high by controlling the cooling of the electrode, and in particular, limit the range where the temperature becomes high by inserting an insert material with high specific resistance between the bonding surfaces. Therefore, deterioration of the base material and the like can be minimized.

As described above, the present invention is an extremely excellent joining method that can greatly reduce the working time and achieve high-quality joining with a compact and safe device as compared with the conventional joining methods. is there.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a method for joining metal materials according to the present invention.

FIG. 2 is a diagram illustrating a temperature distribution at the time of joining metal materials according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal material 2 Metal material 3 Insert material 4 Ring core 5 Primary coil 6 Power cable 7 Primary power supply 8 Electrode 9 Electrode 10 Conductive member 11 Conductive member 12 Underground 13 Choke core

Claims (5)

[Claims] A good magnetic ring core wound with a primary coil is arranged so as to surround a metal end face to be joined by pressing and abutting, and electrodes having a cooling function are arranged on both sides of the joining surface. A metal joining device, wherein a secondary circuit is formed by short-circuiting between the conductive members passing through the outside of the good magnetic ring core. 2. A method for joining metals, wherein the joining apparatus according to claim 1 is used to heat and join a metal joining surface between both electrodes by passing an electric current through a primary coil. 3. The metal according to claim 2, wherein an insert material is sandwiched between the metals to be bonded, and the insert material is melted and diffused, using the bonding apparatus according to claim 1. Joining method. 4. The method according to claim 2, wherein by controlling the distance between the cooling electrode and the bonding surface and the cooling capacity of the electrode, the bonding is performed while controlling the range of high temperature between the bonding metals due to current generation. Item 3. The method for joining metals according to Item 3. 5. The method according to claim 2, wherein one of the metals is buried in the soil, an electrode in contact with the metal on the side opposite to the side buried in the ground is grounded, and the bonding surface is heated and joined. The method for joining metals according to claim 4.