Thermal expansion prevention contact tube

Abstract

The invention discloses an anti-thermal-expansion contact tube, and aims to solve the problems of valve body external expansion, kerf expansion and unstable conduction caused by thermal expansion during working of the anti-thermal-expansion contact tube. Which comprises a metal body, a welding wire channel, an axial kerf and a petal body, and is characterized by further comprising an annular groove formed in the periphery of the petal body and a clamping ring installed in the annular groove. The clamping ring is configured in the mode that in the working state, radial inward elastic restoring force generated by deformation of the clamping ring is mainly used for resisting radial outward thermal expansion of the petal bodies, and therefore opening of the kerfs is restrained. Through creative combination of an annular groove structure and a thermal expansion resisting function, stable control over the dynamic working size of the contact tube is achieved.

Description

Technical Field

[0001] This invention relates to the field of welding equipment technology, and specifically to a conductive nozzle for gas shielded welding. Background Technology

[0002] As a key component in welding equipment that guides the welding wire and conducts high current, the conductive tip's performance and lifespan are directly constrained by the harsh thermal environment. Under operating conditions, the conductive tip primarily bears two types of thermal loads. First, there is internal Joule heating. According to Joule's law, the welding current flowing through the conductive tip generates a large amount of heat due to the conductor's resistance. The rate of heat generation is proportional to the square of the current; that is, the larger the welding current, the more significant the Joule heating effect. This is the fundamental reason for the radially uniform thermal expansion of the conductive tip. Second, there is external molten pool heat. The tip tip is extremely close to the high-temperature molten pool (often exceeding 1500°C), continuously absorbing heat through intense thermal radiation and conduction. This results in a significant temperature gradient between the tip tip and the rear tip, leading to complex and uneven thermal expansion and thermal stress distribution. The coupling effect of these two heat sources causes significant radial outward thermal expansion of the flap at the tip of the open-flap conductive tip, ultimately causing its axial slit to open. Uncontrolled opening of the kerf directly disrupts the geometric accuracy of the welding wire channel, leading to a series of problems such as poor wire feeding, arc drift, and uneven wear of the contact tip, ultimately severely impacting welding quality and shortening the contact tip's lifespan. In the welding process, the vertical distance between the tip face of the gas-shielded welding contact tip and the molten pool surface is typically 10-20 mm. The reasonable range for the through-hole size of the gas-shielded welding contact tip is usually the welding wire diameter + 0.1-0.2 mm. Friction between the welding wire and the inner hole of the contact tip enlarges the inner hole and wire outlet, affecting the wire's conductivity and welding quality; therefore, the contact tip is a consumable part.

[0003] A search revealed existing technologies that employ retaining rings to restrict the conductive tip, such as the patent "A Welding Conductive Tip," application number: 201220054612.5, authorization announcement number: CN 202461781 U. Its independent claim is: 1. A welding conductive tip, comprising a metal body, the metal body having an axially penetrating welding wire channel, and the metal body forming a wire outlet at the front end of the welding wire channel, characterized in that: the front half of the metal body is circumferentially divided into multiple arc-shaped claw-like segments, and the metal body also has retaining rings on the outer peripheral wall of the front half that cause the claw-like segments to retract inward (the purpose of which is to improve conductivity). The instruction manual states that when the diameter of the welding wire channel expands due to prolonged sliding friction with the welding wire, the elastic force of the retaining ring causes each claw to tighten towards the center, ensuring reliable contact between the inner wall of the welding wire channel and the welding wire. For better elasticity and tightness after tightening, adjacent claws are preferably spaced axially with a distance of 0.5–1 mm. To ensure reliable positioning of the retaining ring on the metal body, the front half of the metal body preferably has a circumferentially arranged groove into which the retaining ring is embedded. Therefore, during installation, the retaining ring is directly engaged in the groove, preventing slippage and facilitating installation.

[0004] The above explanation confirms that after the aperture is enlarged, the retaining ring continues to apply pressure, causing the petals to tighten towards the center. To ensure elasticity between the multiple petals and the tightness after closing, the wire outlet of the contact tip is completely closed after static installation. For example, with two petals and a 1.0mm diameter welding wire, the reasonable range for the through-hole size of the contact tip in gas shielded welding is typically the welding wire diameter + 0.1-0.2mm, i.e., a 1.0mm diameter welding wire through-hole of 1.1-1.2mm. The distance between the petals is 0.5-1.0mm. With the retaining ring continuously applying pressure, the wire outlet closes, forming an ellipse with diameters of approximately 0.6 / 1.1mm and 0.7 / 1.2mm. Since 0.6 / 0.7mm is smaller than the 1.0mm welding wire diameter, the continuous compression of the welding wire results in excessive resistance to the contact tip. This directly affects arc stability and weld formation quality, and in severe cases, prevents continuous and stable welding operations, impacting production efficiency and product quality. It is important to note that the "annular groove" in this invention differs fundamentally from the slot mentioned in existing patents in terms of function and structural fit: 1. Different functional purpose and technical status: The "slot" structure in existing patents is not the core of the invention (not placed in Independent Claim 1), but a subordinate means for positioning the retaining ring, aiming to prevent the retaining ring from slipping and to achieve "inward pressure." This precisely indicates that, in the inherent understanding of those skilled in the art, the function of this structure is fixed at "inward pressure." This invention, however, for the first time, takes the combination of "annular groove + retaining ring" as the core inventive point (placed in Independent Claim 1), with the purpose of "resisting the outward thermal expansion of the valve body"—a completely new function, contrary to inherent understanding. 2. Different inventive concepts: The inventive concept of existing patents lies in "inward contraction to increase conductivity"; while the inventive concept of this invention lies in "resisting outward thermal expansion to maintain dynamic stability." The technical problems they solve, the technical means they employ, and the technical effects they achieve are completely opposite in their starting and ending points of technical logic. This invention is a creative functional transformation of a similar structural basis to solve a completely new and opposite technical problem, which is by no means obvious to those skilled in the art.

[0005] Through in-depth analysis, the inventors discovered that: Claim 1 of the prior art does not specify the specific installation structure of its retaining ring, nor does it mention "suppressing thermal expansion." The core objective of this invention lies in: by actively and continuously retracting the petals inward with the retaining ring, the static clamping force on the welding wire is enhanced, and after the through-hole expands, the retaining ring actively and continuously applies inward pressure to tighten the petals towards the center. The aforementioned prior art solution has a fundamental limitation: it completely ignores the extreme combined thermal environment of the contact tip during operation. This thermal environment mainly comes from two aspects: 1. Internal heat source: Joule heat generated by the large welding current passing through the contact tip body. 2. External heat source: high-temperature radiation and heat conduction from the nearby molten welding pool. The retaining ring of the prior art, due to its "inward pressure" design, is based on assumptions under static or normal temperature conditions, and it is completely unable to cope with the complex thermal deformation caused by the aforementioned overlapping internal and external combined thermal loads. Under combined thermal loads, the petals not only heat up from the inside due to Joule heat, but their front end also experiences a dramatic temperature increase due to its proximity to the molten pool, resulting in severe and uneven radial outward thermal expansion. At this point, the existing technology's continuously "inwardly pressurized" retaining ring creates a direct and severe counterforce against the thermal stress of the "outward expansion" of the valve body. This counterforce results in: 1. Extremely high local composite stress at the valve body root and retaining ring contact area, easily triggering material creep and fatigue cracks; 2. Exacerbating irregular torsional deformation at the wire exit (cut end) caused by the gradient; 3. Worsening the extrusion and distortion at the tip of the welding wire through-hole because the expansion is unreasonably constrained. Existing technology does not address, and cannot solve, the fundamentally different technical problem of "suppressing the dynamic outward thermal expansion of the valve body during operation."

[0006] Therefore, how to provide a new type of conductive tip that can actively adapt to and suppress welding thermal expansion, and maintain the smooth wire feeding and structural stability of the conductive tip has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The technical problem to be solved by this invention is to overcome the shortcomings of existing technologies that only consider static clamping and completely ignore dynamic composite thermal load, and to provide a conductive tip structure that can suppress the radial outward expansion deformation of the petal body due to heating under real welding thermal environment (taking into account both Joule heat and molten pool heat), thereby preventing the axial slit from opening and ensuring the stability of the wire outlet size and conductivity.

[0008] To achieve the above objectives, the present invention employs the following technical solution.

[0009] A heat-expansion resistant conductive nozzle includes a nozzle body with an axially penetrating welding wire through-hole and an axial slit dividing the nozzle into at least two segments from the front end. The key feature is the presence of an annular groove on the outer periphery of each segment and a retaining ring installed within the annular groove. The retaining ring is configured such that, after installation, its specific fit with the annular groove (forming a gap, zero gap, or interference fit) generates a radially inward force, primarily resisting the radially outward expansion force generated by the segment under heat during operation, thereby inhibiting the opening of the axial slit. The retaining ring is preferably an open C-shaped retaining ring (also known as a C-shaped retaining spring) made of materials with high elastic limit, high fatigue strength, and good heat resistance, such as spring steel, beryllium bronze, or stainless steel, to ensure stable elastic performance and provide reliable restraint under high-temperature welding conditions.

[0010] While existing technologies use retaining rings on conductive tips, their core function lies in applying radially inward pressure directly to the valve body via the retaining ring to clamp the welding wire. This invention differs fundamentally in the following ways: Structural features: It explicitly defines an "annular groove" and the retaining ring "installed within it." This is not a simple addition, but rather provides a precise positioning and operational reference for the retaining ring to achieve a new function. This feature is not disclosed in Independent Claim 1 of the prior art; Functional features: It revolutionarily redefines the function of the retaining ring, utilizing a specific fit (such as clearance or interference) between the retaining ring and the annular groove to transform its function from "inward contraction" in the prior art to "resistance to outward thermal expansion." This stems from a profound understanding of the novel technical problem of "failure due to thermal expansion"; Combined effect: The aforementioned specific structure serves a specific function, collectively constituting a complete new technical solution to solve a novel problem not addressed by existing technologies, bringing unexpected technical effects.

[0011] In a first specific embodiment of the present invention, when the conductive tip is in a normal operating state, there is a radial gap between the inner wall of the retaining ring and the bottom of the annular groove. This radial gap allows the flap to expand freely to release stress upon initial heating, while when it expands to the point where the bottom of the groove contacts the inner wall of the retaining ring, the retaining ring provides a limit, preventing the slit from opening further.

[0012] In a second specific embodiment of the present invention, when the conductive nozzle is in a normal operating state, the retaining ring is installed in the annular groove and is in an ideal zero-gap fit with the bottom of the groove, thereby providing continuous and stable elastic constraint from the beginning of operation.

[0013] As a third specific embodiment of the present invention, when the conductive nozzle is in a normal operating state, after the retaining ring is installed in the annular groove, a radially inward preset pressure is applied to the bottom of the groove. This preset pressure is directly used to constrain and resist the radially outward expansion force generated when the valve body is heated.

[0014] Preferably, for the scheme with radial clearance, the value of the radial clearance is in the range of 0.01MM---0.2MM, and the optimal value is 0.01MM---0.05MM. This range can effectively balance stress release and limiting accuracy.

[0015] Preferably, at least two elastic open retaining rings are installed side by side in the same annular groove of the valve body.

[0016] Preferably, the groove of the conductive tip is provided with a protrusion.

[0017] Preferably, the protrusion is not located at the cut.

[0018] Preferably, the conductive nozzle body has an axially penetrating welding wire through hole with a size equal to the welding wire diameter plus (0.01-0.15 mm, preferably 0.01-0.05 mm).

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Purpose and Functional Innovation: The function of the retaining ring is redefined from the traditional "applying inward pressure to improve conductivity" to "restraining outward thermal expansion to maintain structural stability," solving the long-neglected problem of thermal deformation. 2. Effective Solution Through Three Paths: Through three different technical paths—"gap buffering + elastic limiting," "zero-gap fit elastic constraint," and "elastic pre-tightening constraint"—the thermal expansion and opening of the kerf are effectively suppressed, improving the universality and reliability of the solution. 3. Significantly Improved Performance: By suppressing thermal expansion deformation, the accuracy of the welding wire channel is ensured, and the stability of the arc is improved. 4. Breakthrough in Environmental Applicability: The constraint scheme of this invention (whether gap buffering, zero-gap fit, or elastic pre-tightening) is designed for dynamic composite thermal loads, which is fundamentally superior to existing technologies based on static assumptions. It enables the contact tip to maintain the effective function of the welding wire channel even when subjected to severe internal and external temperature differences and thermal shocks, demonstrating excellent environmental applicability and robustness under operating conditions. 5. For the first time, a direct and effective suppression solution is provided for the thermal expansion failure mode of the conductive tip, transforming its function from "inward contraction" to "resistance to outward thermal expansion," solving a long-standing pain point in the industry. 6. Structural and functional consistency: The "annular groove" structure ensures the positioning accuracy of the retaining ring, reliably realizing its "resistance to thermal expansion" function. Furthermore, some preferred embodiments of this invention achieve the following additional technical effects: 1. Provides a high-performance optimization solution: The composite retaining ring hierarchical constraint structure further provided by this invention, through a combination of rigid and flexible retaining rings, provides the conductive tip with two intelligent safety measures: "primary buffering" and "ultimate limiting," enabling it to adapt to different welding heat loads and exhibit superior dimensional stability under various working conditions. This synergistic enhancement effect is difficult for those skilled in the art to foresee. 2. When the groove of the conductive tip is provided with a protrusion, in order to prevent the opening of the elastic opening retaining ring from coinciding with the slit, since the retaining ring is a ring structure and there is no positioning device during assembly, the elastic opening retaining ring is easily installed and rotated to the slit position. The opening is the weak point of the elastic retaining ring, and it cannot form a complete constraint force on each slit. By setting the feature of "protrusion", the opening of the retaining ring is prevented from coinciding with the slit, ensuring that the retaining ring can form a complete and uniform constraint force on each slit, thereby solving the problem of the retaining ring coinciding with the slit and ensuring manufacturing consistency. 3. When the through hole size of the conductive tip body divided into two arc-shaped cross-section lobes from the front end face to the rear is the welding wire diameter plus (0.01-0.15MM, optimally 0.01-0.05MM), it can be used for similar welding wire diameters, and the operating efficiency is improved by about 10%, which is particularly suitable for production environments with similar welding wires of different specifications. Due to the increased wear of the through-hole and enhanced wire orientation, the service life of the contact tip is increased by more than three times. The wire orientation is better, making it more suitable for use in robots / special machines. The inward retraction of each lobe brings the wire closer to the inner wall of the wire outlet, improving conductivity by more than 10%. Attached Figure Description

[0020] Figure 1 , 2 Schematic diagram of each part of the segmented conductive nozzle; Figure 3 , 4 : Schematic diagram of a segmented conductive nozzle with raised blocks; Figure 5 : Top view of the wire outlet at the front of the through hole of the split conductive nozzle; Figure 6 : Schematic diagram of elastic open retaining ring; Figure 7 Schematic diagram of the axial cross-section of the segmented conductive nozzle, showing two grooves and two protrusions; Figure 8 Top view of the circumferential cross-section of the segmented conductive tip groove, protrusion, and retaining ring; Figure 9 : Top view of the circumferential cross-section of the groove and protrusion of the segmented conductive nozzle; Figure 10 : A top view of the circumferential cross-section of the four-lobed conductive nozzle groove and protrusion; Figure 11 Theoretically, the retaining ring and the annular groove have no gap or very little contact area. Figure 12 A predetermined, radially inward pressure is continuously applied to the bottom of the retaining ring and the annular groove.

[0021] 1: Conductive tip body; 2: Protrusion block inside the annular groove; 3: Annular groove; 4: Axial slit of the conductive tip; 5: Elastic opening retaining ring; 6, 9: Single-sided radial clearance; 7: Through hole of the segmented conductive tip; 8: Root of the slit of the segmented conductive tip; d1: Slit width; d2: Through hole diameter; d3: Diameter of the front end of the segmented conductive tip; L1: Distance from the front end face of the segmented conductive tip to the groove; L2: Slit length; L3: Length of the segmented conductive tip. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the following description, in conjunction with the accompanying drawings, further illustrates a thermal expansion-resistant conductive nozzle proposed by this invention. It should be specifically noted that the drawings are merely illustrative and not intended to limit the scope of protection of this invention. The details such as the shape and proportions of the components shown in the drawings are only for clearly illustrating the structural relationship; those skilled in the art will understand that equivalent or modified structures can be adopted in actual implementation. The dimensions of various parts of the conductive nozzle in the embodiments (such as the outer diameter of the front end, the slit width, the outer diameter of the groove, the inner diameter of the retaining ring, etc.) can be adapted to different conductive nozzles, welding wire specifications, welding processes, and performance requirements. These embodiments all use an elastic open retaining ring as the core constraint element. The retaining ring is preferably made of spring steel (such as 65Mn, 60Si2Mn, etc.). Spring steel has a high elastic limit, high fatigue strength, and good heat resistance, ensuring that the retaining ring maintains stable elastic performance over a long period under high-temperature welding conditions, providing reliable constraint force. The retaining ring can be adapted to the current magnitude, welding process, and performance requirements; equivalent or modified structures can be adopted in actual implementation. General notes regarding thermal stress: In specific design and material selection, those skilled in the art should ensure, through conventional mechanical calculations or finite element analysis, that the materials of the retaining ring and flap (such as spring steel, copper, etc.) possess sufficient elastic limit and fatigue strength to withstand the thermo-mechanical loads under welding conditions. The design of parameters such as retaining ring stiffness needs to achieve a balance between providing effective constraint and avoiding stress overload. This is a conventional design trade-off for those skilled in the art under the described inventive concept and can be achieved without creative effort.

[0023] Example 1: Elastic constraint of clearance fit This embodiment provides a heat-expansion-resistant conductive nozzle, the core of which lies in the use of an elastic open retaining ring and the intelligent two-stage management of thermal expansion through a clearance fit: first, free buffering, then elastic constraint. A heat-expansion-resistant conductive nozzle includes a nozzle body 1. The center of the nozzle body 1 has a welding wire through-hole 7 extending axially. The front end of the nozzle body 1 is divided into two opposing lobes by a slit 4. An annular groove 3 is machined on the outer periphery of the front part of each of the two lobes. An elastic open retaining ring made of spring steel is installed in the annular groove 3. Figure 1 , 2As shown, taking a welding wire diameter of 0.8 mm as an example, the diameter d2 of the conductive tip through hole 7 is set to 0.85 mm, the width d1 of the slit 4 is 0.03 mm, and the distance L1 from the annular groove 3 to the front end face is 5 mm. The key to this embodiment is that when the conductive tip is in a room temperature assembled state, a single-sided radial gap is formed between the inner wall of the retaining ring 5 and the bottom outer wall of the annular groove 3 in the radial direction. This radial gap is the core of the function of this embodiment, and its value range is 0.01 mm to 0.2 mm (optimal is 0.01 mm to 0.1 mm). For example, the inner diameter of the retaining ring 5 is 5 mm, the wire diameter is 1 mm, the axial width of the annular groove 3 is 1.05 mm, the depth is 1.05 mm, and the bottom outer diameter is 4.95 mm. The front end diameter d3 is 6 mm. Installation at room temperature: Since d3 is larger than the inner diameter of retainer 5, when installing retainer 5 into the annular groove 3, a tool (such as retainer pliers) is needed to moderately open the opening of retainer 5, causing it to elastically deform and temporarily expand its inner diameter to be larger than d3. Then, it is inserted into the annular groove 3. After removing the tool, retainer 5 shrinks due to its own elasticity, and its final inner diameter of 5 mm is larger than the outer diameter of the bottom of the annular groove 3 by 4.95 mm. Thus, a single-sided working gap in the radial direction between the inner wall of retainer 5 and the bottom of the annular groove 3 is obtained that is slightly larger than the design gap by 0.025 mm. The formation of this gap utilizes the coupling effect of natural deformation and elastic recovery during the manufacturing process. This result benefits from the fact that the present invention actively accommodates and utilizes the inherent characteristics of the "kerf shrinkage" process. Without additionally increasing the machining accuracy of the parts, it cleverly and automatically generates the functional gap required to suppress thermal expansion, which is an important hidden advantage of the present invention. This embodiment achieves a unique "two-stage" working mode through the above gap design: First stage: free expansion. When welding begins and the valve body expands radially outward due to heat, the retaining ring 5 does not apply any restraining force during the initial expansion phase due to the radial gap. The valve body can "expand freely" within this gap range, which is the buffer stage. Second stage: Elastic restraint and displacement suppression: When the thermal expansion displacement reaches the gap, the bottom of the annular groove 3 contacts the inner wall of the retaining ring 5. Afterward, any further expansion will compress the retaining ring 5, forcing its opening to tend to widen. The retaining ring 5, by virtue of its elasticity, will generate an elastic restoring force that is opposite to the direction of expansion and increases with the displacement. This force restrains the annular groove 3, limiting further displacement of the valve body; this is the restraint stage. Restraint mechanism: According to the principles of elasticity, when the retaining ring 5 widens, it generates a strong, radially inward elastic restoring force. The greater the expansion force, the greater the restoring force generated by the retaining ring 5, until the two reach equilibrium. Therefore, the thermal expansion of the valve body is strictly limited, and its final expansion displacement is only slightly greater than the initial preset gap (e.g., increasing from 0.025 mm to 0.05 mm), and it will not open indefinitely. This ensures that the expansion of the wire outlet is minimal, thereby guaranteeing the stability of the welding arc.There is no fixed temperature value at the contact tip; it dynamically changes according to factors such as welding process, current magnitude, and working time. Factory normal welding tests were conducted: non-pulse welding, 0.8mm welding wire diameter, 0.85mm through-hole diameter, 130A current, mixed gas protection. The retaining ring 5 provides sufficient constraint force to constrain the annular groove, limiting the circumferential opening of the axial slit and ensuring the conductivity and directionality of the welding wire. This results in a longer service life for this contact tip than the normal welding time of contact tips used in the factory.

[0024] Example 2: Zero-clearance fit elastic constraint This embodiment provides another implementation method, the core of which is that the elastic retaining ring 5 and the annular groove 3 are in an ideal zero-gap fit state at room temperature, achieving continuous and stable elastic constraint from the beginning of operation. A heat-resistant conductive nozzle includes a conductive nozzle body 1, the center of which has a welding wire through-hole 7 extending axially. The front end of the conductive nozzle body 1 is divided into two opposing lobes by a slit 4, and an annular groove 3 is machined on the outer periphery of the front part of the two lobes. An elastic open retaining ring 5, preferably a C-shaped retaining ring, is made of a material with excellent elasticity and heat resistance, such as spring steel. A retaining ring 5 is installed in the annular groove 3, such as... Figure 1 , 11As shown, the key to this embodiment is that the nominal size of the inner diameter of the retaining ring 5 in its free state is the same as the nominal size of the outer diameter of the bottom of the annular groove 3. After assembly, at room temperature, the inner wall of the retaining ring 5 and the outer wall of the bottom of the annular groove 3 have a theoretical zero clearance fit or a very small interference / clearance (its value is within the range of conventional machining tolerances). Installation at room temperature: To install the retaining ring 5 into the annular groove 3, a tool (such as retaining ring pliers) is needed to moderately open the opening of the retaining ring 5 to cause elastic deformation, thus inserting it into the annular groove 3. After removing the tool, the retaining ring 5 precisely contracts due to its elasticity and is installed in the annular groove 3. 1. Instant constraint: When welding begins, any slight radial outward expansion tendency of the petal body due to heating will be immediately blocked by the inner wall of the retaining ring 5. 2. Continuous elastic constraint: The expansion force forces the opening of the retaining ring 5 to produce a very small expansion deformation. This deformation will instantly trigger the elastic restoring force of the retaining ring 5, which is inward and opposite to the direction of the expansion force. This constraint force starts from zero and increases linearly with the expansion displacement, providing a smooth and continuous damping for thermal expansion from beginning to end. 3. Constraint effect: When the petal expands radially outward due to heating, the continuous elastic constraint force provided by the retaining ring 5 can effectively suppress the opening of the axial slit, controlling the expansion of the wire outlet within a very low range, thereby ensuring the stability of the welding arc. This embodiment provides instantaneous and continuous elastic constraint. When the petal expands due to heating, the elastic deformation of the retaining ring can effectively buffer mechanical impact, making the constraint process respond smoothly. This embodiment is suitable for occasions with extremely high requirements for thermal response speed and operational stability. Its advantages are that the constraint has no delay and no extreme changes, and can provide more stable conductive contact. Compared with Embodiment 1, it sacrifices a small amount of initial stress buffering in exchange for a more linear constraint characteristic throughout the entire cycle. The above description is only a detailed explanation of the present invention using a conductive nozzle with two valves and a retaining ring as an example. It is understood that the technical solution described in the present invention can be easily extended to conductive nozzles with three, four or more valves by those skilled in the art. As long as the structure of "groove and retaining ring cooperating to constrain the thermal expansion of valves" is adopted, it falls within the protection scope of the present invention.

[0025] Example 3: Preload combined with elastic constraint This embodiment provides a third implementation method, the core of which is: after installation, the elastic retaining ring applies a radially inward active pre-tightening force to the annular groove 3, achieving a "preemptive" constraint on thermal expansion. A thermal expansion-resistant conductive nozzle includes a conductive nozzle body 1, the center of which has a welding wire through-hole 7 extending axially. The front end of the conductive nozzle body 1 is divided into two opposing lobes by a slit 4, and an annular groove 3 is machined on the outer periphery of the front part of the two lobes. A retaining ring 5, preferably a C-shaped retaining ring, is made of a material with excellent elasticity and heat resistance, such as spring steel. The retaining ring 5 is installed in the annular groove 3, as... Figure 1 、 12As shown, taking a welding wire diameter of 1.0 mm as an example, the diameter d2 of the conductive tip through hole 7 is set to 1.05 mm, the width of the slit 4 is d1 = 0.03 mm, and the distance from the groove 3 to the front end face is L1 = 5 mm. The key point of this embodiment is that when the conductive tip is in the room temperature assembly state, the inner wall of the retaining ring 5 continuously applies a radially inward, predetermined pressure to the bottom of the annular groove 3. For example, the inner diameter of the retaining ring 5 is 5 mm, the wire diameter is 1 mm, the axial width of the annular groove 3 is 1.05 mm, the depth is 1.05 mm, and the bottom outer diameter is 5.1 mm. The front end diameter d3 = 6 mm. Installation at room temperature: Since d3 is larger than the inner diameter of retaining ring 5, installing retaining ring 5 into the annular groove 3 requires the use of a tool (such as retaining ring pliers) to moderately open the opening of retaining ring 5, causing it to elastically deform and temporarily expand its inner diameter to be larger than d3. Then, it is inserted into the annular groove 3. After removing the tool, retaining ring 5, due to its strong elastic recovery tendency, attempts to shrink back to its smaller free inner diameter of 5mm. Due to the mechanical obstruction of the annular groove 3, retaining ring 5 cannot fully shrink, thus forming a static equilibrium system between its own elastic recovery force and the supporting reaction force at the bottom of the annular groove 3. This system manifests as retaining ring 5 continuously applying a radially inward, predetermined pressure to the bottom of the annular groove 3. Preload end state: Before welding begins, the two halves are already in a preloaded state, clamped inward by retaining ring 5. This preload force constitutes the first strong line of defense against thermal expansion. Two-stage constraint stage: 1. Overcoming pre-tightening stage: At the start of welding, the valve body generates expansion force due to heat. When the expansion force is less than the pre-tightening force, the valve body cannot produce any outward macroscopic displacement, and its thermal expansion is completely suppressed within the microscopic elastic deformation range of the material. 2. When the expansion force is greater than the pre-tightening force, the valve body begins to overcome the pre-tightening force and generates outward displacement. At this time, the displacement will cause the retaining ring 5 to deform further, thereby stimulating a much larger additional elastic recovery force than in Embodiments 1 and 2. Therefore, the subsequent expansion of the valve body will be subject to extremely strong constraint. The numerical design of the preset pressure should ensure that after being superimposed with the expected thermal stress, it is still within the safe bearing range of the retaining ring and valve body materials. This design can significantly improve the initial stiffness of the valve body against deformation, while the elasticity of the material provides a guarantee for coping with instantaneous overload. It is particularly suitable for welding scenarios with high requirements for high current and strong thermal load. It "locks up" the deformation space of the valve body at the working temperature to the greatest extent through active mechanical preloading. The constraint mechanism of this embodiment is that the pre-tightening force constitutes an active defense against thermal expansion. The thermal expansion force of the valve body must first overcome the preload before outward displacement can begin. The final thermal displacement depends on the difference between thermal expansion and preload (directly proportional), and is inversely proportional to the clamp's resistance to deformation, exhibiting the strongest restraint. Through proper design, the thermal displacement can be suppressed to an extremely low level, providing the strongest resistance to thermal deformation.It is important to note that the "pre-tightening force" in Embodiment 3 of this invention is fundamentally different from the prior art mentioned in the background section. The pressure in the prior art aims to "continuously clamp the welding wire to improve conductivity," and its mechanical object and purpose are static and focused on conductivity. In contrast, the pre-tightening force in this invention aims to "resist the outward thermal expansion of the petal body itself," and its mechanical object and purpose are dynamic and focused on structural stability. The technical problems they solve are completely different. Assembly, pre-tightening state realization, and proof of no interference with the welding wire: After assembly and installation, the retaining ring 5 continuously applies a radially inward preset pressure to the bottom of the annular groove 3. Regarding the effect of this preset force on the welding wire, it should be specifically noted that its direct effect is to cause a slight, center-oriented elastic inward contraction tendency in both petals. This inward contraction is strictly limited, its limit being the complete closure of the slit. Taking a specific design as an example: with a welding wire diameter of 1.0 mm, the diameter d2 of the conductive nozzle through-hole 7 is set to 1.05 mm, the width d1 of the slit 4 is 0.03 mm, and the distance L1 from the front end face of the groove 3 is 5 mm. Under the preset pressure, even if the two lobes retract to completely close the slit, the minimum theoretical through-hole diameter of the wire outlet at the front end of the conductive nozzle is only 1.05 - 0.03 = 1.02 mm, which is still greater than the welding wire diameter of 1.0 mm. Therefore, the welding wire always has a gap in the channel, is in a state of smooth movement without interference, and will not be subjected to harmful radial compression from the lobes. The preset pressure of the retaining ring acts entirely on the constraint of the lobes themselves, is reserved to resist their thermal expansion during operation, and will not be converted into clamping force on the welding wire.

[0026] Example 4: Composite Elastic Open-Ended Clamping Ring Graded Constraint Structure This embodiment is a further optimization of any of the above embodiments, aiming to achieve graded and intelligent constraint of thermal expansion to adapt to complex working conditions. 1. Structural features: Two elastic open retaining rings 5 ​​are installed side by side in the same annular groove 3 of the valve body. Preferably, these two retaining rings are made of spring steel, but are designed to have significantly different radial stiffnesses (e.g., one is more rigid and the other is less rigid, with the inner diameter of the more rigid one being slightly larger, such as 5.05 for the more rigid and 5 for the less rigid). 2. Working principle: When the valve body expands due to heat: In the early stages of expansion or when the heat load is small, the expansion force is first borne by the less rigid elastic open retaining ring 5, which provides gentle constraint, effectively absorbing thermal shock and avoiding rigid collisions. As the heat load continues to increase, causing the less rigid retaining ring 5 to deform significantly, the more rigid retaining ring 5 begins to dominate the constraint, providing strong support force to ensure that the final thermal displacement of the valve body is limited to a safe range. This composite structure combining rigidity and flexibility constitutes an inherent stress buffering mechanism.

[0027] Example 5: Setting up protruding blocks to form a complete and uniform constraint force at the opening. This embodiment is a further optimization of any of the above embodiments, aiming to prevent axial movement and circumferential rotation of the elastic open retaining ring, prevent the opening of the retaining ring 5 from coinciding with the cut, and optimize the constraint force on the cut. A thermal expansion-resistant conductive nozzle has a protrusion 2 within the annular groove 3 in the above embodiments, such as... Figure 3 , 4 As shown, the axial cross-section of the segmented conductive nozzle includes an annular groove 3, a protrusion 2, and an elastic open retaining ring 5. When setting the annular groove 3, a protrusion 2 is left inside the annular groove 3. The width of the protrusion 2 is slightly smaller than the opening width of the elastic open retaining ring 5 (e.g., the retaining ring opening is 1 mm, and the protrusion is 0.8 mm), and it is not at the cut. The elastic opening retaining ring 5 is installed in the annular groove 3, and its opening is installed on both sides of the protrusion 2 to prevent the elastic opening retaining ring 5 from rotating circumferentially and moving axially, and to prevent the opening of the elastic opening retaining ring 5 from coinciding with the slit, so as to ensure that the elastic opening retaining ring can form a complete and uniform constraint force on each slit. Figure 7 shows a schematic diagram of the axial cross section of the two annular grooves 3 and the two protrusions 2: First, an annular groove 3 slightly larger than the wire diameter of the two retaining rings 5 ​​is opened on the outer peripheral wall of the front half of the conductive tip. Two protrusions 2 are left in the annular groove 3. The two protrusions 2 are opposite each other in their respective tracks. The two protrusions 2 are not at the slit. The two elastic opening retaining rings 5 ​​are respectively placed in the two annular grooves 3. The openings of the two elastic opening retaining rings 5 ​​are respectively on both sides of the two protrusions 2. The two elastic opening retaining rings 5 ​​cannot move axially or rotate circumferentially. Figure 8 This is a top view of the circumferential cross-section of the segmented conductive nozzle groove, protrusion, and retaining ring. Figure 9 : Top view of the circumferential cross-section of the groove and protrusion of the segmented conductive nozzle; Figure 10 A top-view diagram of the circumferential cross-section of the four-lobed conductive nozzle groove and protrusions: First, an annular groove 3, slightly larger than the wire diameter of the four retaining rings 5, is made on the outer peripheral wall of the front half of the conductive nozzle. Four protrusions 2 are placed within the annular groove 3, positioned opposite each other within their respective tracks, and not at the openings. The four elastically open retaining rings 5 ​​are then placed into the four annular grooves 3, with their openings on either side of the four protrusions 2. The four retaining rings 5 ​​cannot move axially or rotate circumferentially. Other structures are the same as in the above embodiment and will not be repeated here.

[0028] A thermal expansion resistant conductive tip is suitable for different welding wire diameters: because the flap has free elasticity, the through-hole narrows, and it resists outward thermal expansion, the same conductive tip is suitable for welding wires of 0.8mm and 0.9mm; and 0.9mm and 1.0mm. Figure 9As shown, the length of the conductive tip L3 = 45 mm, the slit length L2 = 30 mm, the distance from the front end face of the segmented conductive tip to the groove L1 = 5 mm, the slit width d1 = 0.03 mm, the through hole d2 = 0.95 mm, and the front diameter of the segmented conductive tip d3 = 6 mm. Other conditions are as described in Examples 1, 2, 3, 4, and 5. The reasonable range for the through hole size of the gas shielded welding conductive tip is usually the welding wire diameter + 0.1-0.2 mm. That is, 0.8 mm is suitable for 0.9-1.0 mm; 0.9 mm is suitable for 1.0-1.1 mm. For through-holes with a diameter of 0.95mm, 0.8mm diameter welding wire is within this range; for diameters of 0.9mm welding wire, the range is smaller, resulting in better wire conductivity, through-hole wear resistance, and welding wire directionality. For through-holes with a diameter d2 of 1.05mm and a kerf width d1 of 0.03mm, the applicable range for diameters of 0.9mm and 1.0mm is: 0.9mm: 1.0-1.1mm; 1.0mm: 1.1-1.2mm. For diameters of 0.9mm welding wire, the range is smaller, resulting in better wire conductivity, through-hole wear resistance, and welding wire directionality.

[0029] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Since consumable electrode nozzles (such as those used in gas shielded welding and submerged arc welding) are widely used and come in many specifications and styles, the scope of protection of the present invention is not limited thereto. Any technical solution that adopts the core principle of "installing a retaining ring within the annular groove of the valve body, and the retaining ring is mainly used to resist thermal expansion during operation," regardless of the specific form of the retaining ring, the gap, or the magnitude of the preload, falls within the scope of protection of the present invention.

Claims

1. A thermally stable contact tip, comprising a contact tip body having a wire passage and an axial slit, the axial slit being divided into at least two lobes from a front end to a rear end, characterized in that, Also include: An annular groove is arranged on the periphery of the valve body, and a clasp is installed in the annular groove; the clasp is configured to generate a radial inward elastic restoring force by its own deformation in the working state, which is mainly used to resist the radial outward thermal expansion of the valve body due to heat, thereby inhibiting the opening of the axial slit.

2. A thermal expansion compensating contact tip as defined in claim 1, wherein: The clasp is an elastic open clasp.

3. A thermal expansion compensating contact tip as defined in claim 2, wherein: The inner wall of the elastic open clasp has a single-side radial gap with the bottom of the annular groove.

4. A thermal expansion compensating contact tip as defined in claim 3, wherein: The single-side radial gap is not greater than 0.2MM.

5. A thermal expansion compensating contact tip as defined in claim 4, wherein: The single-side radial gap is in the range of 0.01MM-0.1MM.

6. A thermal expansion compensating contact tip as defined in claim 2, wherein: The inner wall of the elastic open clasp has a theoretical zero-gap fit with the bottom of the annular groove.

7. A thermal expansion compensating contact tip as defined in claim 2 wherein: The elastic open clasp exerts a preset radial inward pressure on the bottom of the annular groove after being installed in the annular groove.

8. A thermal expansion compensating contact tip according to claim 1 wherein: The number of the clasp is at least two, and they are installed side by side in the annular groove.

9. A thermal expansion compensating contact tip according to claim 1 wherein: At least one protruding block is arranged in the conductive nozzle body groove.

10. A thermal expansion compensating contact tip according to claim 1, wherein: The size of the welding wire through hole of the conductive nozzle is the diameter of the welding wire plus (0.01-0.15MM, and the optimal value is 0.01-0.05MM).

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