JP2018017545A - Connecting method of element wire of temperature sensor and extension lead wire, and connecting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting method of an element wire of a temperature sensor which is composed of a thermos-coupling or temperature-measuring resistor and an extension lead wire which can efficiently and easily perform connection work, can make a connecting part compact in size while maintaining high quality, is favorable in the workability of the cabling and installation of a cable, can be installed even in a narrow space, and can produce a product which is easy in management, and a connecting structure.SOLUTION: A welding end part having a prescribed length is formed by bending an end part of a connecting side of either of an element wire and a lead wire into a substantially-L shape in advance, an end part of the other wire is made to abut on a bent part being a root portion of the welding end part or the vicinity of the bent part, welding is performed toward the root portion from a tip of the welding end part in a state that the end part of the other wire abuts thereon, the welding end part and the end part of the other wire abutting on the welding end part are welded to each other, and both the wires are substantially-coaxially welded and joined to each other at a position of the root portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a connection method and a connection structure between an element wire of a temperature sensor made of a thermocouple or a resistance temperature detector and an extension lead wire.

  As this type of connection method, for example, welding of the ends of both wires or crimping via a metal sleeve is known (for example, see Patent Documents 1 to 5). The methods described in Patent Documents 1 to 3 connect the ends of both lines by welding, specifically brazing or soldering, and mold the periphery with an insulating resin. In such a connection by brazing or soldering, if there are multiple element wires and lead wires, it is difficult to connect them coaxially because the adjacent wires are in the way and it is also necessary to scrape off the flux , Cost increase, quality variation.

  In addition, such a brazed or soldered connection portion has a structure having a considerably larger diameter than the wire diameter in order to maintain quality such as connection strength and electrical connection state. If there are multiple element wires and lead wires, the number of these connection portions is as many as that, and it is necessary to wrap the insulation tape so as not to short-circuit each other or arrange them at intervals, so resin-molded connections The entire portion is larger than the sensor cable or extension cable and protrudes in the outer diameter direction, and insulation failure is likely to occur. In addition, brazing and soldering tend to cause heat to be transferred to the film of the lead wire and melt, so that the length of the lead wire exposure becomes longer, and the resin mold becomes longer accordingly.

  When the connecting portion becomes large in this manner, the cable is caught in the surrounding equipment when the cable is routed, so that workability is reduced, the space for installation is limited by the connecting portion, and the management cost increases.

  On the other hand, in the methods described in Patent Documents 4 and 5, a metal sleeve for connection is prepared, both wires are inserted into the recesses at both ends, and are connected by crimping or welding, and the resin mold is also used. It is. However, such crimping also causes variations in connection strength. In addition, welding, specifically brazing, is poor in workability, causes variations in quality such as connection strength and electrical connection state, and, similarly to the above, the welding point becomes large, A similar problem occurs when the connecting portion becomes large. Further, since the connection is made via the metal sleeve, the number of parts increases, which causes an increase in cost.

Japanese Utility Model Publication No. 3-21462 Japanese Examined Patent Publication No. 7-48056 JP-A-7-35626 Japanese Utility Model Publication No. 58-8135 Utility Model Registration No. 3157595

  Therefore, in view of the above-mentioned situation, the present invention intends to solve the problem that the connection work can be performed efficiently and easily without using a metal sleeve, and the quality of the connection strength and the electrical connection state can be stabilized. In addition to maintaining excellent quality, the connection part can be made compact, the cable routing and installation workability is good, it can be installed in a narrow space, and the product should be easy to manage The object is to provide a connection method and connection structure between an element wire of a temperature sensor made of a thermocouple or a resistance temperature detector and an extension lead wire.

  In order to solve the above problems, the present inventor has focused on fusion welding with higher energy density. Since fusion welding is considerably higher energy than brazing in particular, the thermocouple that becomes a relatively thin wire and the element wire on the resistance temperature detector side are immediately melted down, and the compensating conductor side It was known that it could not be joined well with other lead wires.

  The present inventor has further investigated the problem of such fusion welding, and once the end of one line is bent in an L shape and energy is given to this in the axial direction, the other line is The energy is also moved in the axial direction for one line without melting away, so that it is possible to prevent the energy from concentrating and melting in one place, and the other line. The end of the other line is gradually brought into contact with the bent position at the base of the bent end of one line by indirect heat transfer through the end of the other line. As a result, it was found that both wires could be welded and joined substantially coaxially, and the present invention was completed.

  That is, the present invention includes the following inventions.

  (1) A method for connecting an element wire of a temperature sensor made of a thermocouple or a resistance temperature detector and an extension lead wire, and one of the element wire and the lead wire to be connected to each other The end of the other wire is formed in a substantially L shape in advance to form a melting end having a predetermined length, and the end of the other line at or near the bent portion serving as the root of the melting end. In a state where the end of the second wire is in contact with the end of the other line, and performing fusion welding from the tip of the melting end toward the base, A method of connecting an element wire and a lead wire of a temperature sensor, comprising a step of melting an end portion of the other wire in contact and welding the two wires substantially coaxially at the position of the base portion.

  (2) The temperature sensor according to (1), wherein a wire having a relatively large heat capacity among the element wire and the lead wire is set as the one wire, and the melting end portion is formed on the one wire. How to connect element wires and lead wires.

  (3) The method for connecting the element wire and the lead wire of the temperature sensor according to (1) or (2), wherein the fusion welding is laser welding.

  (4) A step of passing a cylindrical insulating tube through the one wire or the other wire before the step of bringing the end of the other wire into contact with the bent portion of the melting end or the vicinity thereof The element wire and the lead wire of the temperature sensor according to any one of (1) to (3), further including a step of moving the insulating tube to a weld joint location and covering the weld tube after the step of the welding joint How to connect with.

  (5) A connection structure between an element wire of a temperature sensor made of a thermocouple or a resistance temperature detector and a lead wire for extension, and the connection side of one of the element wire and the lead wire connected to each other The end of the wire is bent in a substantially L shape in advance to form a melting end portion of a predetermined length, and the end of the other line is placed at or near the bent portion that becomes the root portion of the melting end portion. In the contacted state, fusion welding is performed from the tip of the melting end portion toward the root portion, and the melting end portion and the end portion of the other wire in contact with the melting end portion are melted, A structure for connecting an element wire and a lead wire of a temperature sensor, wherein both wires are welded and joined substantially coaxially at the position of the portion.

  According to the connection method and connection structure between the element wire and the extension lead wire of the temperature sensor comprising the thermocouple or the resistance temperature detector according to the present invention as described above, there are a plurality of element wires and lead wires, respectively. The end portion for melting protruding in an L shape can be fusion-bonded from the side without interfering with the adjacent line, and it is possible to provide a product with good workability and stable quality.

  In addition, the high energy fusion welding process compared to brazing, etc. makes it possible to weld and join both wires in a nearly coaxial shape without melting them down, thus realizing a high strength connection in a short time with high workability and high efficiency. can do. Therefore, the size of the joint determined by the length of the melting end is not much larger than the wire diameter like brazing or soldering, and the quality of the connection strength and electrical connection state is good. Can be maintained, and the length of stripping of the lead wire can be minimized, so that the connecting part can be made more compact than conventional brazing and the workability of cable routing and installation is also improved. Good, can be installed in a small space, and can be easily managed. Moreover, parts such as a metal sleeve for connecting the wires are not necessary, and an increase in cost can be avoided.

  Further, of the element wires and the lead wires, a wire having a relatively large heat capacity is set as the one wire, and the melting end portion is formed on the one wire, thereby inputting the melting end portion. The energy of fusion welding can be made higher, and processing can be performed efficiently. It is of course possible to form an end portion for melting by using the wire having a relatively small capacity as one of the wires, and to input energy to this, but relatively delicate adjustment is required.

  In addition, since the fusion welding is laser welding, the machining can be performed more efficiently and stably.

  In addition, a step of passing a cylindrical insulating tube through the one line or the other line before the step of bringing the end of the other line into contact with the bent portion of the melting end or the vicinity thereof. And providing the step of moving the insulating tube to the welded joint and placing it on the periphery after the step of welding and bonding, so that the joints can be efficiently insulated and arranged, and the resin molding is performed on the periphery In this case, the resin can be easily filled. In conventional brazing and the like, since the joint portion becomes large, such an insulating tube cannot be covered, and for insulation, an operation of winding an insulating tape is necessary. Since it can be made compact, it is possible to use such an insulating tube.

(A)-(c) is explanatory drawing which shows the procedure of the connection method of the element wire of the temperature sensor which concerns on this invention, and the extension lead wire. (A)-(c) is explanatory drawing which similarly shows the procedure of a connection method. The photograph which compared the joining state of an Example and a comparative example.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, the present invention relates to a method for connecting element wires 11,... Of a temperature sensor made of a thermocouple or a resistance thermometer and extension lead wires 21,. In the following embodiment, the element wire 11 is an internal strand of the sheath thermocouple 1 and the lead wire 21 is a lead wire of the compensating lead wire 2 for connection, but is not limited to this. In this example, two element wires 11 and two lead wires 21 are used, but the number may be three, four, or more.

  A specific connection procedure is as follows. First, as shown in FIGS. 1A and 1B, one of the element wire 11 and the lead wire 21 to be connected to each other, in this example, the connection of the lead wire 21 is connected. The side end portion 21a is bent in a substantially L shape in advance to form the melting end portion 3 having a predetermined length.

  The melting end 3 is preferably formed on the element wire 11 or the lead wire 21 which has a relatively large heat capacity. As a result, it is easy to adjust the output of the fusion welding process, the other wire is easily melted by heat conduction, and a good weld joint is easily obtained without being melted off in the middle. In the case of a thermocouple, the lead wire on the compensation wire side for normal connection is thicker and larger in heat capacity than the element wire. In this case, the melting end portion 3 is formed on the lead wire 21 side as in this example. It will be preferable.

  However, the present invention is not limited to such a case where the melting end portion is provided on the lead wire side, and it is of course included to be formed on the element side. When joining a line of material such as copper or silver that has a low laser absorptivity (reflecting) and a line that does not, a melting end is provided on the side of the line that does not, and the material that has a poor absorption is heat transfer. It is a preferable example to make it melt.

  In any case, it is possible to weld and join the element wire and the lead wire coaxially, cleanly, efficiently and stably by subjecting the bent end portion 3 for fusion to the axial direction. It is. Further, the “predetermined length” of the melting end portion 3 may be appropriately set according to the size and material of both lines, the type of fusion welding described later, and the like. Although the bending angle is also approximately 90 °, other angles may be used.

  Next, as shown in FIG. 1C, the other wire, that is, the end portion 11a of the element wire 11 is brought into contact with the bent portion 3b which is the root portion of the melting end portion 3 of the lead wire 21 or the vicinity thereof. Let The end portion 11a may be a circular end portion obtained by cutting the end portion of the straight element wire 11 at right angles to the axis, or an element by heat conduction by gaining a contact area with the root portion of the melting end portion 3 In order to increase the melting efficiency of the wire 11, it may be a concave curved surface shape or one that is cut obliquely, or may be a short L-shaped end that does not adversely affect the fusion welding of the end 3 for melting. The shape of the end portion 11a is not particularly limited.

  Next, as shown in FIG. 2 (a), with the end portion 11a of the element wire 11 in contact, the root portion (bent portion) from the tip 3a of the melting end portion 3 of the lead wire 21 as shown by the arrow in the figure. Fusion welding is performed toward the portion 3b) to melt the melting end portion 3 and the end portion 11a of the element wire 11 in contact therewith. Specifically, laser welding is preferable for the fusion welding process, but TIG welding and plasma welding which are non-molten electrode arc welding are also preferable. In the case of laser welding, a known one such as a YAG laser, a CO2 laser, or a semiconductor laser can be applied, and it may be pulsed or continuous. If the pulse is used, it is easy to adjust the energy, but the yield is good.

  By this fusion welding process, as shown in FIG. 2B, both wires (element wire 11 and lead wire 21) are welded and joined substantially coaxially at the position of the root portion (bent portion 3b). Thereby, the connection structure S of the element wire 11 and the extension lead wire 21 of the temperature sensor according to the present invention is configured.

  Furthermore, in this example, the polyamide insulating tube 4 made of polyamide, which has been passed through the lead wire 21 in advance, is moved to the welding joint (welded joint 5) and covered around it. However, in this example, the insulating tube 4 is passed through the lead wire 21 side, but it may of course be passed through the element wire 11 side. Of course, such an insulating tube 4 can be omitted.

  Further, as in the prior art (for example, Patent Documents 1 to 5 described above), a sleeve is put between the sheath of the thermocouple 1 outside the connection structure S and the outer skin of the compensation conductor 2, and an inorganic insulating powder or A structure filled with an insulating resin can be used, or other forms can be employed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can of course be implemented in various forms without departing from the gist of the present invention.

  Next, in connecting the four elements of the sheath thermocouple to the four lead wires of the compensation lead wire to prepare the sample, the sample joined portion of Example 1 connected by laser welding according to the present invention, The joint portion of the sample of Comparative Example 1 connected by conventional brazing will be described.

  Each sample of Example 1 and Comparative Example 1 has SUS316, four Type K element wires having an outer diameter of φ0.74 mm inside a stainless sheath tube having an outer diameter of φ4.8 mm and an inner diameter of 3.7 mm. A sheath thermocouple (commonly known as Type K sheath thermocouple) filled with an inorganic insulating material of MgO and a lead wire for Tyep K having an outer diameter of about 0.6 mm on four skins made of perfluoroethylene propene copolymer (FEP) Connected to the internal compensation lead wire, common (same).

  In Example 1, a 1.0 mm portion from the end of each lead wire is bent into a substantially L shape to form an end for melting, and the end of the element wire is brought into contact with the root (bent portion). In this state, the tip surface of the melting end portion was irradiated with a YAG laser in the axial direction of the melting end portion. Irradiation conditions were 400 V, pulse 20 ms, spot diameter 600 μm, and welding was completed with five irradiations.

  In Comparative Example 1, silver brazing (BAg7) defined in JIS Z 3261 was used, and the ends of the lead wire and the element wire were connected to each other by silver brazing with a water welder (voltage 60 to 80 V).

  3A is a photograph of the joint portion of Example 1, and FIG. 3B is a photograph of the joint portion of Comparative Example 1. As a result of conducting a tensile test on the joint part of Example 1 and Comparative Example 1, both were about a push-pull gauge 58N, and the lead part was broken before the joint part broke. It can be seen that Example 1 maintains a sufficient joint strength similar to that of Comparative Example 1 while having a slim joint portion that is substantially the same as the wire diameter of the lead wire.

DESCRIPTION OF SYMBOLS S Connection structure 1 Sheath thermocouple 2 Compensation conducting wire 3 Melting end 3a Tip 3b Bending part 4 Insulating tube 5 Welded joint 11 Element wire 11a End 21 Lead wire 21a End

Claims (5)

A method for connecting an element wire of a temperature sensor composed of a thermocouple or a resistance temperature detector and a lead wire for extension,
Of the element wire and the lead wire connected to each other, a step of bending an end portion on the connection side of one wire in a substantially L shape in advance to form a melting end portion having a predetermined length;
A step of bringing the end of the other line into contact with a bent portion that is a base portion of the melting end portion or the vicinity thereof;
In the state where the end of the other line is in contact, fusion welding is performed from the tip of the melting end toward the root, and the end of the melting and the end of the other line in contact with the end Melting the part, and welding and joining the two lines substantially coaxially at the position of the root part;
Connecting method of temperature sensor element wire and lead wire.   The element wire of the temperature sensor according to claim 1, wherein a wire having a relatively large heat capacity among the element wire and the lead wire is defined as the one wire, and the melting end portion is formed on the one wire. Connection method with lead wire.   The method for connecting an element wire and a lead wire of a temperature sensor according to claim 1 or 2, wherein the fusion welding is laser welding.   And a step of passing a cylindrical insulating tube through the one line or the other line before the step of bringing the end of the other line into contact with the bent portion of the melting end or the vicinity thereof. The connection between the element wire and the lead wire of the temperature sensor according to any one of claims 1 to 3, further comprising a step of moving the insulating tube to a welding joint portion and covering the insulation tube after the welding joint step. Method. It is a connection structure between the temperature sensor element wire and the extension lead wire of the temperature sensor comprising a thermocouple or a resistance temperature detector,
Of the element wire and the lead wire that are connected to each other, an end portion on the connection side of one of the wires is bent in a substantially L shape in advance to form a melting end portion of a predetermined length, and the melting end portion In a state where the end of the other line is brought into contact with the bent portion serving as a root portion or the vicinity thereof, fusion welding is performed from the tip of the melting end portion toward the root portion, and the melting end portion and The temperature sensor element wire and the lead wire are formed by melting the end portion of the other wire in contact with this and welding and joining both wires substantially coaxially at the position of the root portion. Connection structure.