Welding rod special for die-casting die

Abstract

The utility model discloses a special welding rod for a die-casting die, which relates to the technical field of welding rods, and comprises a core material and a plurality of layers of composite coatings sequentially coated from inside to outside, and the plurality of layers of composite coatings are composed of a bonding layer, a functional alloy layer and a surface treatment layer. Wherein the bonding layer is metallurgically bonded with the core material through a metal dendritic crystal structure, the interface bonding force is enhanced, and the problem that the compactness of a welding layer is reduced due to coating stripping of a traditional welding rod is solved; the functional alloy layer is of a wave-shaped interface structure formed by alternately stacking nickel-based alloy and cobalt-based alloy, tungsten carbide particle strengthening and honeycomb pore energy absorption design are combined, thermal stress is dispersed, and the thermal fatigue resistance is improved. The surface treatment layer is filled with rare earth oxide and laser micro-melting concave-convex lines through spiral micro-grooves, the molten pool fluidity and the heat conduction efficiency are optimized, and the welding defects are reduced. According to the welding rod, through multi-layer collaborative design, the problems that the tensile strength is insufficient, and high-temperature cracks are prone to occurring in the die-casting die repairing process are solved.

Description

Technical Field

[0001] This utility model relates to the field of welding electrode technology, specifically a welding electrode for die casting molds. Background Technology

[0002] In the field of die casting mold repair, welding rods are a key material, and their performance directly affects the quality and service life of mold repair.

[0003] Traditional die-casting mold repair welding rods suffer from insufficient bonding between the core material and the coating. Insufficient bonding reduces the density of the weld layer, leading to a decrease in the tensile strength of the repaired area. Furthermore, under the high temperature and high pressure conditions of die-casting molds, fatigue cracks are easily induced, significantly shortening the service life of the mold. To address this issue, we propose a special welding rod for die-casting molds. Utility Model Content

[0004] This utility model addresses the shortcomings of existing technologies by proposing a special welding electrode for die casting molds.

[0005] In order to solve the above-mentioned technical problems, the present invention solves the problem of insufficient bonding force of the internal structure of welding rods in the prior art through the following technical solution.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A special welding electrode for die casting molds includes a core material and a multi-layer composite coating. The multi-layer composite coating consists of a bonding layer, a functional alloy layer and a surface treatment layer from the inside out. The bonding layer has a metal dendritic structure that is metallurgically bonded to the core material.

[0008] Preferably, the functional alloy layer is composed of alternating layers of nickel-based alloy and cobalt-based alloy, with a wavy interface structure formed between the alloy layers.

[0009] Preferably, the nickel-based alloy layer contains dispersed tungsten carbide particles, and the cobalt-based alloy layer has a honeycomb porous structure embedded within it.

[0010] Preferably, the outer surface of the surface treatment layer is provided with axially extending spiral microgrooves, and the grooves are filled with rare earth oxide powder.

[0011] Preferably, the bonding layer comprises a three-layer substructure, consisting of a columnar crystalline region, an equiaxed crystalline region, and a nanocrystalline region, in sequence.

[0012] Preferably, the outer surface of the surface treatment layer is laser micro-melting to form a continuous textured surface, and the height difference between the textured surfaces varies periodically along the welding electrode axis.

[0013] Preferably, the cross-section of the multilayer composite coating has an asymmetrical structure, forming a thickened transition zone at the tip of the welding electrode, where the coating thickness gradually increases towards the tip.

[0014] Preferably, three equidistant flow channels are formed along the axial direction inside the core material, and the flow channels are filled with a low-melting-point alloy core.

[0015] Preferably, the flow channel has a funnel-shaped opening at the end of the welding electrode.

[0016] Preferably, a spiral guide rib is fixedly provided on the inner wall of the guide channel.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention achieves metallurgical bonding between the core material and the coating through the metal dendritic structure design of the bonding layer in the multi-layer composite coating, significantly enhancing the interfacial bonding force, effectively improving the density and tensile strength of the weld layer, reducing the risk of fatigue cracks under high temperature and high pressure conditions, and thus extending the service life of the die-casting mold.

[0019] The functional alloy layer adopts a wave-shaped interface structure with alternating superposition of nickel-based and cobalt-based alloys. Combined with the dispersion strengthening of tungsten carbide particles and the energy absorption characteristics of honeycomb pores, it can effectively disperse thermal stress and mechanical stress, improve the coating's resistance to thermal fatigue and high-temperature stability, and adapt to the complex working conditions of die-casting molds.

[0020] The spiral microgrooves of the surface treatment layer are filled with rare earth oxide powder, which, together with the continuous concave and convex textures formed by laser micro-melting, can improve the fluidity of the molten pool and the heat conduction efficiency during the welding process, reduce the oxidation tendency, and reduce porosity and crack defects. At the same time, the flow channel design enhances the directional flow of low melting point alloys, further improving the uniformity and precision of welding repair. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0023] Figure 2 This is an exploded view of the overall structure of this utility model;

[0024] Figure 3 This is a side view of the rear end of the welding electrode of this utility model;

[0025] Figure 4 This is a side view of the front end of the welding electrode of this utility model;

[0026] Figure 5 This is a schematic diagram showing the increased thickness of the thickened transition zone in this utility model;

[0027] Figure 6 This is a schematic diagram of the flow channel structure of this utility model.

[0028] Drawing number explanation: 1. Core material; 2. Bonding layer; 3. Functional alloy layer; 4. Surface treatment layer; 5. Nickel-based alloy layer; 6. Cobalt-based alloy layer; 7. Spiral microgroove; 8. Embossed texture; 9. Flow channel; 10. Flow guide rib. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings. Example

[0030] Please see Figures 1-6 A special welding electrode for die-casting molds includes a core material 1 and a multi-layer composite coating. The multi-layer composite coating, from the inside out, consists of a bonding layer 2, a functional alloy layer 3, and a surface treatment layer 4. The bonding layer 2 has a metal dendritic structure that is metallurgically bonded to the core material 1. During high-temperature welding, the dendritic structure forms an interlocking effect, enhancing the coating's anti-peeling ability, thereby improving the density and tensile strength of the weld layer. This design effectively avoids cracking defects caused by insufficient bonding force in traditional welding electrodes, and especially in the high-temperature and high-pressure environment of die-casting molds, it can significantly extend the service life of the mold after repair.

[0031] The following describes some embodiments of this application in detail with reference to the accompanying drawings:

[0032] Please see Figures 1-6 This invention achieves metallurgical bonding between the core material 1 and the coating by designing the metal dendritic structure of the bonding layer 2 in the multi-layer composite coating, significantly enhancing the interfacial bonding force, effectively improving the density and tensile strength of the weld layer, reducing the risk of fatigue cracks under high temperature and high pressure conditions, and thus extending the service life of the die-casting mold.

[0033] The functional alloy layer 3 is composed of alternating layers of nickel-based alloy layer 5 and cobalt-based alloy layer 6, forming a wavy interface structure between the alloy layers. The high-temperature strength of the nickel-based alloy and the corrosion resistance of the cobalt-based alloy work synergistically, and the wavy interface can disperse thermal and mechanical stress, reducing stress concentration. This alternating superposition structure has excellent thermal fatigue resistance under high-temperature cyclic conditions. At the same time, the wavy interface increases the interlayer contact area, enhances the overall toughness of the coating, and is suitable for the complex thermo-mechanical coupling environment of die-casting molds.

[0034] Furthermore, the nickel-based alloy layer 5 contains dispersed tungsten carbide particles, which significantly improve the wear resistance and compressive strength of the coating through a hard phase strengthening mechanism; the cobalt-based alloy layer 6 has an embedded honeycomb pore structure, which alleviates thermal expansion stress through the pore energy absorption effect and stores lubricating substances to reduce the coefficient of friction. The combination of tungsten carbide and honeycomb pores not only ensures the load-bearing capacity of the coating, but also improves its high-temperature stability, making it particularly suitable for the repair of high-wear areas of die-casting molds.

[0035] In addition, the outer surface of the surface treatment layer 4 is provided with axially extending spiral microgrooves 7, which are filled with rare earth oxide powder to optimize the flowability and wettability of the weld pool. The spiral microgrooves 7 guide the molten metal to flow in a directional manner, reducing spatter; the rare earth oxide powder decomposes at high temperature, releasing active elements to inhibit oxidation reaction and reduce porosity;

[0036] Meanwhile, the outer surface of the surface treatment layer 4 is treated with laser micro-melting to form continuous concave-convex textures 8. The height difference between the concave and convex textures varies periodically along the welding electrode axis. This design can adjust the axial heat conduction rate during welding, avoid local overheating or undercooling, and reduce the risk of hot cracking. The turbulence effect formed by the concave-convex textures 8 can also promote the escape of gas in the molten pool, further reducing porosity defects and improving the density of the weld layer.

[0037] In this technical solution, the bonding layer 2 comprises a three-layer substructure: a columnar crystalline region, an equiaxed crystalline region, and a nanocrystalline region. The columnar crystalline region provides vertical mechanical support, enhancing shear resistance; the equiaxed crystalline region improves the coating's toughness and impact resistance through uniform grain distribution; and the nanocrystalline region utilizes grain boundary strengthening effects to improve surface hardness and wear resistance. The three-layer gradient structure works synergistically to balance strength and toughness, ensuring the coating's reliability under dynamic loads.

[0038] Meanwhile, the multi-layer composite coating has an asymmetrical cross-section, forming a thickened transition zone at the tip of the welding electrode. The coating thickness in this zone gradually increases towards the tip, adapting to the geometric requirements of different parts during mold repair. The thickened transition zone enhances the erosion resistance of the front coating, especially under the impact of high-pressure molten metal, reducing the risk of coating peeling and ensuring a smooth transition between the repair layer and the mold substrate.

[0039] In this technical solution, three equidistant flow channels 9 are formed along the axial direction within the core material 1. The flow channels 9 are filled with a low-melting-point alloy core. During welding, the low-melting-point alloy preferentially melts to form a flowing medium, which is then directionally transported to the repair area through the flow channels 9, accelerating the formation of the molten pool and improving filling efficiency. The equidistant distribution of the channels ensures uniform diffusion of the molten metal, avoiding localized incomplete fusion defects, and is suitable for repairing deep grooves or complex structures.

[0040] In this technical solution, the connecting gear 16 is vertically distributed along the axial direction of the drive rod 11 and is fixed coaxially with the drive rod 11. This design ensures that the rotation axis of the connecting gear 16 is completely aligned with the drive rod 11, avoiding meshing errors or power loss caused by gear misalignment. At the same time, the vertically distributed gear layout optimizes space utilization and makes the meshing of the drive rod 11 and the auxiliary gear 17 more stable, which is especially suitable for long-term reliable operation under high-speed conditions.

[0041] Furthermore, the flow channel 9 has a funnel-shaped opening at the tip of the welding electrode, which expands the outflow cross-section of the molten alloy and reduces flow resistance. The funnel-shaped opening guides the alloy to a radial distribution, enhancing its coverage of the repair area, making it particularly suitable for repairing large-area or curved molds. The gradual change in the opening structure also reduces turbulence and ensures the stability of the alloy flow.

[0042] Furthermore, a spiral guide rib 10 is fixedly provided on the inner wall of the flow channel 9. By generating a swirling effect, it promotes the full mixing of the low-melting-point alloy and the core material 1. The spiral ribs can extend the alloy flow path, increase the heat exchange time, and ensure that the alloy is heated uniformly. At the same time, the spiral structure prevents channel blockage, improves the continuity and controllability of the welding process, and ultimately enhances the uniformity and bonding strength of the repair layer.

[0043] The dendritic structure is handled in this device as follows:

[0044] First, the core material 1 is made of high-purity low-carbon steel or nickel-based alloy as the matrix to ensure good ductility and high-temperature stability. The bonding layer 2 material is made of alloy powder containing strong carbide-forming elements such as niobium and vanadium to promote dendrite nucleation.

[0045] Then, by using laser cladding or plasma transfer arc technology, the bonding layer 2 material is uniformly coated on the surface of the core material 1. The energy input and the cooling rate of the molten pool are precisely controlled to allow the molten metal to solidify rapidly and form a directional columnar dendritic structure. Gradient cooling induces the grains to transition from columnar crystals to equiaxed crystals and nanocrystals, forming a three-layer substructure.

[0046] By adding rare earth elements as nucleating agents, the energy barrier for crystal nucleation is reduced, and the dendrite density is increased. Electromagnetic stirring or ultrasonic vibration technology is used to break the uniformity of the temperature and concentration fields in the molten pool, promote dendrite branching growth, and form an interlocking network structure.

[0047] Subsequently, the bonding layer 2 is subjected to aging heat treatment to enhance the metallurgical bond between the dendrites and the core material 1 through atomic diffusion. Finally, laser shock peening is used to eliminate residual stress and improve the fatigue resistance of the dendritic structure.

[0048] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been shown and explained in the embodiments. Without departing from the principles, the implementation of the present invention may have any modifications or variations.

Claims

1. A special welding electrode for die casting molds, characterized in that, include: The core material (1) and the multilayer composite coating, wherein the multilayer composite coating consists of a bonding layer (2), a functional alloy layer (3) and a surface treatment layer (4) from the inside to the outside, and the bonding layer (2) is provided with a metal dendrite structure that is metallurgically bonded to the core material (1).

2. The die-casting mold welding electrode according to claim 1, characterized in that: The functional alloy layer (3) is composed of alternating layers of nickel-based alloy layer (5) and cobalt-based alloy layer (6), forming a wave-shaped interface structure between the alloy layers.

3. The die-casting mold welding electrode according to claim 2, characterized in that: The nickel-based alloy layer (5) contains dispersed tungsten carbide particles, and the cobalt-based alloy layer (6) has a honeycomb pore structure embedded within it.

4. The die-casting mold welding electrode according to claim 1, characterized in that: The outer surface of the surface treatment layer (4) is provided with an axially extending spiral microgroove (7), which is filled with rare earth oxide powder.

5. The die-casting mold welding electrode according to claim 1, characterized in that: The bonding layer (2) comprises a three-layer substructure, consisting of a columnar crystal region, an equiaxed crystal region, and a nanocrystalline region.

6. The special welding electrode for die casting molds according to claim 1, characterized in that: The outer surface of the surface treatment layer (4) is laser micro-melting to form a continuous concave-convex texture (8), and the height difference between the concave and convex textures changes periodically along the welding electrode axis.

7. The die-casting mold welding electrode according to claim 1, characterized in that: The multi-layer composite coating has an asymmetrical cross-section, forming a thickened transition zone at the tip of the welding electrode, where the coating thickness gradually increases towards the tip.

8. The die-casting mold welding electrode according to claim 1, characterized in that: The core material (1) has three equally spaced flow channels (9) along the axial direction, and the flow channels (9) are filled with a low melting point alloy core.

9. The die-casting mold welding electrode according to claim 8, characterized in that: The flow channel (9) has a funnel-shaped opening at the end of the welding rod.

10. A special welding electrode for die casting molds according to claim 9, characterized in that: The inner wall of the flow channel (9) is fixedly provided with a spiral flow guide rib (10).

Images