Copper-plated iron wire / copper-plated steel wire thermocouple and welding process thereof

Abstract

This invention discloses a copper-plated iron wire / copper-plated steel wire thermocouple and its welding process, comprising: a brass rod substrate and a positive lead, wherein a transition solder joint is formed on the surface of the brass rod substrate and the end of the positive lead is connected to the brass rod substrate through the transition solder joint, and the positive lead is configured as either copper-plated iron wire or copper-plated steel wire; and a negative lead, one end of which is connected to a quick-connect terminal for temperature measurement. This invention, through a process design of pure copper wire transition welding, forms a transition solder joint between the brass rod substrate and the positive lead, achieving a high-strength metallurgical bond between the copper-plated iron wire / copper-plated steel wire and the brass rod substrate. The positive lead uses copper-plated iron wire or copper-plated steel wire instead of the industry-standard pure copper wire, significantly reducing the cost of the substrate. Simultaneously, the pure copper wire is used only as a transition solder, in very small quantities, and does not increase manufacturing costs. The cost reduction effect is significant when scaled up for mass production.

Description

Technical Field

[0001] This invention relates to the field of thermocouple manufacturing technology, and in particular to a copper-plated iron wire / copper-plated steel wire thermocouple and its welding process. Background Technology

[0002] As a core component in industrial temperature sensing, thermocouples are widely used in metallurgy, chemical industry, power industry, machinery manufacturing, industrial automation control, and many other fields due to their advantages of wide temperature measurement range, fast response speed, and strong environmental adaptability. The welding structure between the thermocouple end substrate and the leads, as well as the selection of lead materials, directly determine the product's welding reliability, service life, temperature measurement stability, and overall manufacturing cost, making them key technical aspects of thermocouple product development.

[0003] Currently, the positive leads of conventional thermocouple products in the industry are mostly made of pure copper wire, which results in high raw material procurement costs and is greatly affected by fluctuations in copper market prices, making product cost control difficult.

[0004] To reduce costs, the industry has attempted to use low-cost substrates such as copper-plated iron wire and copper-plated steel wire to replace pure copper wire as the positive electrode lead. However, there has always been a core technical bottleneck that is difficult to overcome: the brass rod substrate and the copper-plated iron wire / copper-plated steel wire are dissimilar materials and cannot be directly and reliably welded by conventional argon arc welding. During the welding process, defects such as incomplete welding, false welding, insufficient bonding force, and joint cracking are prone to occur, resulting in an extremely low welding yield. This problem has become a common technical challenge that has long existed in the thermocouple industry, and a solution that can be stably mass-produced and implemented has not yet been formed. Summary of the Invention

[0005] This invention provides a copper-plated iron wire / copper-plated steel wire thermocouple and its welding process. Through a process design of pure copper wire transition welding, a transition solder joint is formed between the brass rod substrate and the positive lead, achieving a high-strength metallurgical bond between the copper-plated iron wire / copper-plated steel wire and the brass rod substrate. The positive lead uses copper-plated iron wire or copper-plated steel wire instead of the industry-standard pure copper wire, significantly reducing the cost of the substrate. At the same time, the pure copper wire is only used as a transition solder, and the amount used is extremely small, so it will not increase the manufacturing cost. The cost reduction effect of large-scale production is outstanding.

[0006] To solve the above-mentioned technical problems, the present invention provides a copper-plated iron wire / copper-plated steel wire thermocouple, comprising:

[0007] The brass rod substrate and the positive electrode lead are provided. The surface of the brass rod substrate has a transition solder joint and the end of the positive electrode lead is connected to the brass rod substrate through the transition solder joint. The positive electrode lead is configured as either copper-plated iron wire or copper-plated steel wire.

[0008] The negative lead is connected at one end to a quick-connect terminal for temperature measurement, which includes two independent contacts, a positive terminal and a negative terminal, which are insulated from each other.

[0009] As a preferred embodiment of the above technical solution, a protective sleeve is provided on one side of the brass rod substrate, and one end of the negative electrode lead extends into the interior of the protective sleeve.

[0010] As a preferred embodiment of the above technical solution, the end of the positive lead away from the transition solder joint is connected to a terminal block, and the temperature measurement signal quick-connect terminal block is configured as a dual-core quick-connect terminal block.

[0011] As a preferred embodiment of the above technical solution, the surface of the brass rod substrate is provided with a groove, the end of the positive electrode lead extends into the groove, and the transition solder joint fills the welding gap between the groove and the positive electrode lead.

[0012] As a preferred embodiment of the above technical solution, a positioning solder joint is formed at one end of the positive electrode lead near the brass rod substrate.

[0013] This invention also provides a welding process for copper-plated iron wire / copper-plated steel wire thermocouples, specifically including the following steps:

[0014] Step 1: Select the brass rod substrate, positive lead and pure copper wire of appropriate specifications to be welded, and clean the brass rod substrate, positive lead and pure copper wire to be welded areas to remove surface oxide layer, oil and impurities.

[0015] Step 2: Use pure copper wire as a transition solder and weld it to the end of the positive lead using argon arc welding.

[0016] Step 3: Precisely align the pre-connected positive lead end with the brass rod base to be welded, and continue to use argon arc welding to weld the aligned part. During the welding process, the pure copper wire is completely melted and evenly filled into the gap between the brass rod base and the positive lead to form a transition weld point. Then, the positive lead is welded to the end of the brass rod base to form a positioning weld point.

[0017] Step 4: After installing the protective sleeve on the end of the brass rod base, install the negative lead and connect the temperature measurement signal quick-connect terminal to the other end of the negative lead to assemble a copper-plated iron wire thermocouple, thus completing the temperature measurement circuit assembly.

[0018] This invention provides a copper-plated iron wire / copper-plated steel wire thermocouple and its welding process. It comprises a brass rod substrate, a positive lead, a transition solder joint, and a negative lead. Through a pure copper wire transition welding process design, a transition solder joint is formed between the brass rod substrate and the positive lead, achieving a high-strength metallurgical bond between the copper-plated iron wire / copper-plated steel wire and the brass rod substrate. This effectively solves the industry problems of incomplete welding, cracking, and poor bonding strength that easily occur when directly welding dissimilar materials. The welded joint has stable performance and a high yield rate, meeting the requirements for long-term stable use of thermocouples. The positive lead uses copper-plated iron wire or copper-plated steel wire instead of the industry-standard pure copper wire, significantly reducing the cost of the base material. Meanwhile, the pure copper wire is used only as a transition solder in very small quantities, without adding extra manufacturing costs. Large-scale production results in significant cost reduction. Furthermore, it possesses tensile strength, bending resistance, and vibration resistance far superior to pure copper wire, improving the fatigue resistance of the lead at the base material level.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the thermocouple of the present invention.

[0021] In the diagram: 1. Brass rod base, 11. Protective sleeve, 2. Positive lead, 21. Terminal block, 22. Positioning solder joint, 3. Transition solder joint, 4. Negative lead, 5. Quick-connect terminal block for temperature measurement signal. Detailed Implementation

[0022] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] Example 1:

[0024] See Figure 1 This invention provides a copper-plated iron wire / copper-plated steel wire thermocouple and its welding process, including:

[0025] The brass rod substrate 1 and the positive lead 2 are provided. A transition solder joint 3 is formed on the surface of the brass rod substrate 1 and the end of the positive lead 2 is connected to the brass rod substrate 1 through the transition solder joint 3. The positive lead 2 is set as either copper-plated iron wire or copper-plated steel wire.

[0026] The negative lead 4 is connected to a temperature measurement signal quick-connect terminal 5 at one end. The temperature measurement signal quick-connect terminal 5 includes two independent contacts, a positive terminal and a negative terminal, which are insulated from each other.

[0027] This embodiment provides a copper-plated iron wire / copper-plated steel wire thermocouple, which has a brass rod substrate 1, a positive lead 2, a transition solder joint 3, and a negative lead 4. Through a process design of pure copper wire transition welding, a transition solder joint 3 is formed between the brass rod substrate 1 and the positive lead 2, realizing a high-strength metallurgical bond between the copper-plated iron wire / copper-plated steel wire and the brass rod substrate 1. This effectively solves the industry problems of poor welding, cracking, and poor bonding force that easily occur when directly welding dissimilar materials. The welded joint has stable performance and a high yield rate, which can meet the requirements for long-term stable use of thermocouples. The positive lead 2 uses copper-plated iron wire or copper-plated steel wire instead of the industry-standard pure copper wire, which significantly reduces the cost of the base material. At the same time, the pure copper wire is only used as a transition solder, and the amount used is very small, so it will not increase the manufacturing cost. The cost reduction effect of large-scale production is outstanding. In addition, it has tensile strength, bending resistance, and vibration resistance far superior to pure copper wire, which improves the fatigue resistance of the lead at the base material level.

[0028] In a further embodiment of this invention, a protective sleeve 11 is provided on one side of the brass rod substrate 1, and one end of the negative lead 4 extends into the interior of the protective sleeve 11.

[0029] In this embodiment, a protective sleeve 11 is provided on one side of the brass rod base 1, which can wrap and protect the welding joint area and the root of the negative lead 4. On the one hand, it can effectively isolate air, water vapor and industrial corrosive media, and avoid oxidation and corrosion failure at the root. On the other hand, it can form an anti-bending support for the root of the negative lead 4, further reducing the risk of wire breakage caused by stress concentration and improving the product's adaptability under harsh working conditions.

[0030] In a further embodiment of this invention, the end of the positive lead 2 away from the transition solder joint 3 is connected to a terminal 21, and the temperature measurement signal quick-connect terminal 5 is configured as a dual-core quick-connect terminal.

[0031] In this embodiment, the quick-connect terminal 5 for temperature measurement signals can be configured with two independent contact points, a positive and a negative, that are mutually insulated, or a single contact point. The single contact point is connected to the negative lead 4. The negative leads 4 connected to the two independent contact points are then connected to the second lead to form an independent temperature measurement signal circuit, which forms a clear functional boundary with the grounding protection circuit, effectively avoiding problems such as short circuits and electromagnetic interference in the temperature measurement signal. The end of the second lead is equipped with a connector to ensure the integrity of the temperature measurement circuit and the stability of signal transmission, making it suitable for complex industrial environments.

[0032] In a further embodiment of this invention, the surface of the brass rod substrate 1 is provided with a groove, the end of the positive lead 2 extends into the groove, and the transition solder joint 3 fills the welding gap between the groove and the positive lead 2.

[0033] The limiting structure of the welding groove on the surface of the brass rod substrate 1 in this embodiment can be selectively set according to different products and usage requirements. This can further optimize the stress distribution at the welding point, significantly extend the overall service life of the thermocouple, and reduce on-site maintenance costs.

[0034] In a further embodiment of this invention, a positioning solder joint 22 is formed at one end of the positive lead 2 near the brass rod substrate 1.

[0035] The formation of the positioning solder joint 22 in this embodiment can further protect the position of the transition solder joint, prevent it from being easily bent and deformed, and improve its service life.

[0036] Example 2:

[0037] Based on the above embodiments, the present invention also provides a welding process for copper-plated iron wire / copper-plated steel wire thermocouples, specifically including the following steps:

[0038] Step 1: Select the brass rod substrate 1, positive lead 2 and pure copper wire of appropriate specifications to be welded, and clean the brass rod substrate 1, positive lead 2 and pure copper wire to be welded areas to remove surface oxide layer, oil and impurities.

[0039] Step 2: Use pure copper wire as a transition solder and weld it to the end of the positive lead 2 using argon arc welding.

[0040] Step 3: Precisely align the pre-connected positive lead 2 end with the brass rod base 1 to be welded part, and continue to use argon arc welding process to weld the aligned part. During the welding process, the pure copper wire is completely melted and evenly filled into the gap between the brass rod base 1 and the positive lead 2 to form a transition weld point 3. Then weld the positive lead 2 to the end of the brass rod base 1 to form a positioning weld point 22.

[0041] Step 4: After fitting the protective sleeve 11 onto the end of the brass rod base 1, install the negative lead 4, and connect and install the temperature measurement signal quick-connect terminal 5 at the other end of the negative lead 4 to assemble a copper-plated iron wire thermocouple, thus completing the temperature measurement circuit assembly.

[0042] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A copper-plated iron wire / copper-plated steel wire thermocouple, characterized in that, include: The brass rod substrate (1) and the positive electrode lead (2) are provided. A transition solder joint (3) is formed on the surface of the brass rod substrate (1) and the end of the positive electrode lead (2) is connected to the brass rod substrate (1) through the transition solder joint (3). The positive electrode lead (2) is provided as either copper-plated iron wire or copper-plated steel wire. The negative lead (4) is connected to a temperature measurement signal quick-connect terminal (5) at one end. The temperature measurement signal quick-connect terminal (5) includes two independent contact points, a positive terminal and a negative terminal, which are insulated from each other.

2. The copper-plated iron wire / copper-plated steel wire thermocouple according to claim 1, characterized in that, A protective sleeve (11) is provided on one side of the brass rod base (1), and one end of the negative lead (4) extends into the protective sleeve (11).

3. The copper-plated iron wire / copper-plated steel wire thermocouple according to claim 1, characterized in that, The positive lead (2) is connected to a terminal (21) at the end away from the transition solder joint (3), and the temperature measurement signal quick-connect terminal (5) is configured as a dual-core quick-connect terminal.

4. The copper-plated iron wire / copper-plated steel wire thermocouple according to claim 1, characterized in that, The surface of the brass rod base (1) is provided with a slot, the end of the positive lead (2) extends into the slot, and the transition solder joint (3) fills the welding gap between the slot and the positive lead (2).

5. A copper-plated iron wire / copper-plated steel wire thermocouple according to claim 1, characterized in that, The positive lead (2) has a positioning solder joint (22) at one end near the brass rod substrate (1).

6. A welding process for copper-plated iron wire / copper-plated steel wire thermocouples, characterized in that, Specifically, the following steps are included: Step 1: Select the brass rod substrate (1), positive lead (2) and pure copper wire of appropriate specifications to be welded, and clean the brass rod substrate (1), positive lead (2) and pure copper wire to be welded area to remove surface oxide layer, oil and impurities. Step 2: Use pure copper wire as a transition solder and use argon arc welding to weld and fix the pure copper wire to the end of the positive lead (2); Step 3: Align the pre-connected positive lead (2) end with the brass rod base (1) to be welded precisely, and continue to use argon arc welding to weld the aligned part. During the welding process, the pure copper wire is completely melted and evenly filled into the gap between the brass rod base (1) and the positive lead (2) to form a transition weld point (3). Then, weld the positive lead (2) to the end of the brass rod base (1) to form a positioning weld point (22). Step 4: After installing the protective sleeve (11) on the end of the brass rod base (1), install the negative lead (4) and connect the temperature measurement signal quick-connect terminal (5) to the other end of the negative lead (4) to assemble a copper-plated iron wire thermocouple and complete the temperature measurement circuit assembly.

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