JP2021018951A - Inorganic insulation cable and weld method thereof - Google Patents

Abstract

To provide an inorganic insulation cable capable of suppressing weld failure when welding a fixing component on a metal sheath, and a weld method thereof.SOLUTION: There is provided an inorganic insulation cable in which an insulation material formed of an inorganic material is filled between a core wire being a conductor wire and a metal sheath for coating the core wire, the cable has a fixing component weld so as to surround a periphery of the sheath. The fixing component is mating welded to the sheath so that a weld part extends in an axial direction along a gap of a contact surface between the weld part and the sheath and a thickness of the weld part does not reach a thickness of the sheath, by radiation of fiber laser beam to a boundary between the fixing component and the sheath.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inorganic insulated cable in which a fixing component is welded on a metal sheath and a welding method thereof.

Inorganic insulation (MI) cables are insulated by covering a lead wire (core wire) such as copper with a metal sheath such as stainless steel or nickel alloy, and filling an inorganic substance (insulating material) such as magnesium oxide between the lead wire and the metal sheath. It is a cable that has been used. Inorganic insulated cables are resistant to harsh environments such as high temperatures, and are used for signal cables and sheath thermocouples. Fixing parts (sleeve, mounting screws, flanges, bosses) for mounting on the device or the like are attached to the inorganic insulated cable by welding.

As welding of the inorganic insulating cable and the fixing component, for example, there is a method of fillet welding by heating the corner where the side peripheral surface of the inorganic insulating cable and the upper end surface of the fixing component are joined with plasma or a laser. The metal sheath of the inorganic insulated cable is thin, and in welding with the fixing part placed on the sheath, it is difficult to always keep the welded state in the same state even if the welding conditions are constant.

For example, in the case of fillet welding by plasma welding, outside air is entrained in the weld metal due to conditions such as shield gas (plasma gas), and the gas is not released into the atmosphere during solidification, and blow holes are generated by being trapped. If the amount of penetration is shallow, an unmelted portion may occur and a defect may occur due to poor penetration. Further, in the case of fillet welding by YAG laser welding, the welding width is narrower than that in plasma welding, so it is necessary to increase the beam output in order to increase the leg length and throat thickness of the welded portion, which may cause welding cracks.

As described in Patent Document 1, an invention of a connector welding method for an inorganic insulated cable that prevents the occurrence of welding defects due to variations in the penetration depth of the sheath is also disclosed. Further, as described in Patent Document 2, an invention of a highly reliable temperature sensor and a method for manufacturing the same, which can cope with a reduction in the diameter of a welded part and a miniaturization of a temperature sensor, is also disclosed.

Special Fair 03-028125 Japanese Unexamined Patent Publication No. 2006-090746

However, in the techniques described in Patent Documents 1 and 2, welding defects are prevented by inclining and irradiating the end of the connector with a laser beam, but the welded portion is inclined with respect to the axial direction of the inorganic insulating cable. If welding is attempted to a deep position, the penetration width reaches the sheath thickness, and the welded portion may be blown off by the internal pressure of the sheath, resulting in welding defects such as blow holes.

Therefore, an object of the present invention is to provide an inorganic insulating cable and a welding method thereof that suppress welding defects when welding a fixing part on a metal sheath.

In order to solve the above problems, the present invention is an inorganic insulating cable in which an inorganic insulating material is filled between a core wire which is a conducting wire and a metal sheath covering the core wire so as to surround the outer periphery of the sheath. The fixing part has a fixing part welded to the sheath, and the welded portion is axially along the gap of the contact surface with the sheath by irradiating the boundary with the sheath with a fiber laser beam. It is characterized in that it is face-welded to the sheath so as to advance and not reach the thickness of the sheath.

Further, the present invention is a method of welding a fixing component to an inorganic insulating cable in which an inorganic insulating material is filled between a core wire as a lead wire and a metal sheath covering the core wire so as to surround the outer periphery of the sheath. Then, the sheath covered with the fixing component is erected, a fiber laser beam is vertically irradiated at the boundary between the fixing component and the sheath, and the welded portion is advanced in the axial direction of the sheath to cause the welded portion. It is characterized in that the mating surfaces are welded so as not to reach the thickness of the sheath.

Further, in the method of welding the inorganic insulated cable, the sheath is rotated to irradiate a fiber laser beam along the boundary between the adapter and the sheath.

According to the present invention, it is possible to suppress welding defects when welding a fixing component on a metal sheath of an inorganic insulated cable. By performing mating surface welding so as to melt the minute gap between the metal sheath and the contact surface of the fixing part by fiber laser welding, the welded part is formed vertically and the welding range is up to about 4 times the sheath thickness. Since it blends in, there is no concern about poor blending.

Further, since the welded portion is formed parallel to the axial direction of the inorganic insulating cable, the penetration width does not reach the sheath thickness, and the occurrence of welding defects such as penetrating the metal sheath can be suppressed. In fiber laser welding, since the spot diameter of the beam is smaller than that of YAG laser welding or the like, heat input is small and welding cracks are unlikely to occur. In addition, since the penetration is deep, the welding strength is also high.

It is a top view and the front view which shows the inorganic insulation cable which welded the fixing part by the welding method of the inorganic insulation cable of this invention. It is a figure which shows the welding apparatus for performing the welding method of the inorganic insulated cable of this invention. It is a figure which compared the welded part by the welding method of the inorganic insulated cable of this invention, and the welded part by another welding method. It is a photograph which shows the cross section of the welded part by the welding method of the inorganic insulation cable of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Those having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

First, an inorganic insulated cable in which fixing parts are welded by the method of welding an inorganic insulated cable of the present invention will be described. FIG. 1 is a plan view (a) and a front view (b) of the inorganic insulated cable. FIG. 2 is a diagram showing a welding device for welding an inorganic insulated cable.

As shown in FIG. 1, the inorganic insulated cable 100 has an inorganic substance such as magnesium oxide between a core wire 200 which is a conducting wire such as copper and a metal sheath 300 such as stainless steel or nickel alloy that covers the core wire 200. It is a cable used for a signal cable, a sheath thermocouple, or the like, which is filled with an insulating material 400 made of.

In order to attach and fix the inorganic insulating cable 100 to an apparatus or the like, a fixing component 500 is welded all around the sheath 300 so as to surround the outer circumference. The fixing part 500 is a metal part such as stainless steel or nickel alloy, and has a shape in which a hole through which the sheath 300 penetrates is formed. Further, the fixing component 500 may have a threaded outer periphery or a flange or the like.

The outer peripheral surface of the sheath 300 and the inner peripheral surface of the fixing component 500 are in contact with each other via a slight gap 520, and proceed along the gap 520 from the end (boundary) of the contact surface between the sheath 300 and the adapter 500. The welded portion 510 is formed so as to do so. The gap 520 has the smallest gap size that allows the sheath 300 to slide within the fixing component 500.

The welded portion 510 is a portion in which the outer peripheral surface of the sheath 300 and the inner peripheral surface of the fixing component 500 are melted by heat or the like, so that the contact surfaces are integrally joined. When the welded portion 510 breaks through the sheath 300, it is blown off by the internal pressure of the sheath 300 and welding defects such as blow holes occur. Therefore, the width does not reach the thickness of the sheath 300 along the contact surface from the boundary. It is formed thin, straight and deep toward the back.

As shown in FIG. 2, the welding device 600 of the inorganic insulated cable 100 is fixed to a stage 610, which is a work table for erecting the sheath 300, a chuck 620 for fixing the sheath 300 in an erect state, and a sheath 300. It is a device having a welding head 630 or the like that irradiates a fiber laser beam 640 for welding the component 500, and for performing mating surface welding with the fiber laser beam 640.

The fiber laser beam 640 is a type of laser beam that uses an optical fiber to which a rare earth element is added as a laser medium. Since the fiber laser beam 640 has a small spot diameter and a small amount of heat input, the occurrence of welding cracks can be suppressed.

First, the sheath 300 covered with the fixing component 500 is set on the stage 610 with the axial direction perpendicular to the stage 610, and the fixing component 500 is sandwiched and fixed by the chuck 620.

The welding head 630 is arranged above the stage 610, and the fiber laser beam 640 is irradiated aiming at the boundary between the sheath 300 and the fixing component 500. The angle of the welding head 630 is set between 0 and 30 °, and the welding head 630 is applied perpendicularly to the boundary as much as possible so that the welding portion 610 does not melt in an excessively oblique direction.

At the time of welding, the fiber laser beam 640 may be irradiated along the annular boundary by rotating the stage 610 around the axis at a speed of 30 to 60 mm / sec. Further, the output of the fiber laser beam 640 may be melted vertically (axially) to the back along the gap 520 while adjusting the amount of melting in the range of 100 to 500 W. The width of the welding range is narrow so as not to reach the sheath thickness, and the depth in the vertical direction is as long as about four times the sheath thickness.

FIG. 3 shows (a) a welded portion in which mating surfaces are welded by fiber laser welding, (b) a welded portion in which fillet welding is performed by plasma welding, and (c) a laser beam is obliquely irradiated and welded by YAG laser welding. It is the figure which compared the welded part. FIG. 4 is a photograph showing a cross section of a welded portion obtained by mating surface welding by fiber laser welding.

As shown in FIGS. 3A and 4, when the contact surfaces of the sheath 300 and the fixing component 500 are face-to-face welded with the fiber laser beam 640, the side peripheral surface 310 of the sheath 300 and the fixing component 500 are above. The fiber laser beam 640 is vertically irradiated at the boundary with the end face 530, and the welded portion 510 is formed vertically to the back along the cap 520.

As shown in FIG. 3B, when the side peripheral surface 310 of the sheath 300 and the upper end surface 530 of the fixing component 500 are fillet welded by plasma welding, the welded portion 510a does not reach the corner and a gap is formed from the boundary. Welding failure 540a in which 520 is not filled may occur.

As shown in FIG. 3C, when fillet welding is performed by irradiating a laser beam at an angle in YAG laser welding, a welding defect 540b occurs in which the welded portion 510b reaches the thickness of the sheath 300 and breaks through the sheath 300. There is a risk of Further, in the case of YAG laser welding, if the beam output is increased in order to increase the leg length and throat thickness of the welded portion 510b, welding cracks may occur.

According to the present invention, it is possible to suppress welding defects when welding a fixing component on a metal sheath of an inorganic insulated cable. By performing mating surface welding so as to melt the minute gap between the metal sheath and the contact surface of the fixing part by fiber laser welding, the welded part is formed vertically and the welding range is up to about 4 times the sheath thickness. Since it blends in, there is no concern about poor blending.

Further, since the welded portion is formed parallel to the axial direction of the inorganic insulating cable, the penetration width does not reach the sheath thickness, and the occurrence of welding defects such as penetrating the metal sheath can be suppressed. In fiber laser welding, since the spot diameter of the beam is smaller than that of YAG laser welding or the like, heat input is small and welding cracks are unlikely to occur. In addition, since the penetration is deep, the welding strength is also high.

Examples of the present invention have been described above, but the present invention is not limited thereto.

100: Inorganic insulated cable 200: Core wire 300: Sheath 310: Side peripheral surface 400: Insulating material 500: Fixing part 510: Welded part 520: Gap 530: Upper end surface 540: Welding defect 600: Welding device 610: Stage 620: Chuck 630: Welding head 640: Fiber laser beam

In order to solve the above problems, the present invention is an inorganic insulating cable in which an inorganic insulating material is filled between a core wire which is a conducting wire and a metal sheath covering the core wire so as to surround the outer periphery of the sheath. The fixed part has a fixing part welded to the sheath, and the welded portion is axially along the gap of the contact surface with the sheath by vertically irradiating the fiber laser beam at the boundary with the sheath. It is characterized in that it is face-welded to the sheath so as to advance to a depth four times the thickness of the sheath in the direction and not to reach the thickness of the sheath.

Further, the present invention is a method of welding a fixing component to an inorganic insulating cable in which an inorganic insulating material is filled between a core wire as a lead wire and a metal sheath covering the core wire so as to surround the outer periphery of the sheath. Then, the sheath covered with the fixing component is erected, a fiber laser beam is vertically irradiated at the boundary between the fixing component and the sheath, and the welded portion is advanced in the axial direction of the sheath to cause the welded portion. It is characterized in that the mating surfaces are welded so as to reach a depth four times the thickness of the sheath and not to reach the thickness of the sheath.

Claims (3)

An inorganic insulating cable in which an inorganic insulating material is filled between a core wire that is a lead wire and a metal sheath that covers the core wire.
It has a fixing part welded around the outer circumference of the sheath.
By irradiating the boundary with the sheath with a fiber laser beam, the fixing part reaches the thickness of the sheath so that the welded portion advances in the axial direction along the gap of the contact surface with the sheath. Face-welded to the sheath so as not to
Inorganic insulated cable characterized by that. A method of welding a fixing component to an inorganic insulating cable filled with an inorganic insulating material between a core wire which is a lead wire and a metal sheath covering the core wire so as to surround the outer circumference of the sheath.
The sheath covered with the fixing component is erected.
A fiber laser beam is vertically irradiated at the boundary between the fixing component and the sheath.
The welded portion is advanced in the axial direction of the sheath, and the mating surface is welded so that the welded portion does not reach the thickness of the sheath.
A method of welding an inorganic insulated cable. By rotating the sheath, a fiber laser beam is irradiated along the boundary between the fixing component and the sheath.
The method for welding an inorganic insulated cable according to claim 2.

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