A piston and die-casting machine

Abstract

This application belongs to the field of piston technology and provides a piston including a body. The body includes a head and, from the head to the tail of the body, a first outer peripheral portion and a second outer peripheral portion. The outer diameter of the first outer peripheral portion is larger than the outer diameter of the second outer peripheral portion, causing the first outer peripheral portion to protrude outwards from the outer periphery of the body. A copper alloy cladding layer is provided on the first outer peripheral portion, and a stainless steel cladding layer is provided on the second outer peripheral portion. This application also provides a die-casting machine incorporating this piston. This application solves the technical problem of existing large-diameter pistons being prone to wear and failure under high temperature and high pressure conditions due to the lack of guide ring support.

Description

Technical Field

[0001] This application belongs to the field of piston technology, and particularly relates to a ductile iron piston and a die-casting machine using the piston. Background Technology

[0002] Pistons are core components of internal combustion engines, compressors, and hydraulic systems, and their performance directly determines the efficiency, reliability, and lifespan of the entire machine. Ductile iron (QT600-3) is widely used in the manufacture of pistons for medium and heavy-duty engines and extra-large pistons in hydraulic system cylinders due to its excellent comprehensive mechanical properties (tensile strength ≥600 MPa, elongation ≥3%), casting performance, cost-effectiveness, and superior wear resistance. However, with the development of modern engines towards higher power density, lower fuel consumption, and lower emissions, as well as higher cylinder loads, the working environment of pistons is becoming increasingly demanding. For example, in high-temperature (200–400℃), high-pressure (16–31.5MPa), high-speed, or variable-load operating environments, the limitations of ductile iron pistons are becoming increasingly apparent. Specifically, this can be seen in: (1) Insufficient wear resistance and friction reduction: Although ductile iron itself has a certain wear resistance, under poor lubrication or boundary lubrication conditions, its friction coefficient is high, which can easily lead to abnormal wear of the piston skirt and ring groove, or even serious failures such as "cylinder scoring" or "seizing", shortening the service life of the piston.

[0003] (2) Relatively poor thermal conductivity: Compared with copper alloys, ductile iron has a lower thermal conductivity, which is not conducive to the rapid transfer of heat from the piston top to the cylinder liner and cooling system, resulting in increased piston thermal load and affecting working efficiency.

[0004] (3) Compatibility with cylinder liner: When cast iron pistons are paired with cast iron cylinder liners, adhesive wear (seizing) is likely to occur under extreme conditions.

[0005] Therefore, traditional ultra-large diameter pistons (1500-2400mm) without guide ring support are prone to wear and failure under high temperature and high pressure conditions. Utility Model Content

[0006] The purpose of this application is to provide a piston and a die-casting machine to solve the technical problem that large-diameter pistons in the prior art are prone to wear and failure under high temperature and high pressure conditions due to the lack of guide ring support.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application provide a piston, comprising: The body includes a head and, from the head toward the tail of the body, a first outer peripheral portion and a second outer peripheral portion; wherein, the outer diameter of the first outer peripheral portion is larger than the outer diameter of the second outer peripheral portion, so that the first outer peripheral portion protrudes outward on the outer periphery of the body; the first outer peripheral portion is provided with a copper alloy cladding layer, and the second outer peripheral portion is provided with a stainless steel cladding layer.

[0008] Therefore, a first outwardly protruding outer peripheral structure is set on the outer periphery of the piston as a guide structure, and a copper alloy cladding layer is added to the first outer peripheral part, and a stainless steel cladding layer is added to the second outer peripheral part. This helps to increase the structural strength, wear resistance, high temperature resistance and corrosion resistance of the piston, thereby solving the problem that ultra-large diameter pistons are prone to wear and failure under high temperature and high pressure conditions due to the lack of guide ring support.

[0009] The structure on the outer periphery of the piston body is improved by providing at least two adjacent annular grooves on the first outer periphery for mounting sealing rings. This allows for the installation of sealing rings in the at least two annular grooves on the first outer periphery, forming a multi-stage sealing structure on the piston's outer periphery, which improves the reliability and safety of the entire hydraulic system.

[0010] In one embodiment, the first outer periphery also has a plurality of fluid reservoirs arranged around it, which are used to store hydraulic oil. These reservoirs form evenly distributed oil storage points on the outer peripheral surface of the piston. During the reciprocating motion of the piston, these reservoirs can scrape and store a small amount of hydraulic oil. Under high temperature and high pressure conditions, the hydraulic oil stored in these reservoirs can effectively replenish lubrication and effectively prevent the copper alloy cladding layer on the first outer periphery from directly contacting the cylinder liner.

[0011] In one embodiment, the plurality of liquid reservoirs are spaced apart on the first outer periphery and evenly distributed on both sides of the at least two annular grooves. This creates a replenishment area on the weakly lubricated areas on both sides of the sealing ring, effectively ensuring the working environment of the sealing ring and reducing the possibility of leakage due to abnormal wear in the sealing ring area.

[0012] The structure of the head is improved by providing an annular boss around the center point of the head. The annular boss serves to position the piston during the piston machining and clamping process, and facilitates the placement of the piston on the carrier during the piston transfer process.

[0013] In one embodiment, the head also has a groove located within the annular boss, the groove for storing hydraulic oil. Thus, the groove on the piston head acts as a built-in oil reservoir at the forefront of the action, facilitating rapid filling of the space between the piston tip and the cylinder liner, effectively shortening the pressure build-up time, enabling the piston to start quickly, thereby improving the response speed of the entire hydraulic system and enhancing the smoothness of motion under low-speed conditions.

[0014] In one embodiment, the head end face, excluding the annular boss, is gradually inclined along its outer edge. Thus, during the high-speed movement of the piston, the inclined surface on the piston head helps improve the flow characteristics of the hydraulic fluid, allowing the fluid on the piston head to flow smoothly and diffuse evenly to the outer edge of the head, reaching the outer periphery of the piston effectively, thus reducing hydraulic oil turbulence and vortices.

[0015] The internal structure of the piston body is improved by hollowing it out, creating an opening at the rear that connects to the interior. This design allows for a hollow piston structure, ensuring consistent wall thickness throughout the casting, effectively reducing the risk of casting defects and guaranteeing the internal quality of the piston body. Furthermore, the hollowed-out design reduces the piston's weight. This is advantageous in applications with ultra-large diameter pistons (1500-2400mm), as the lighter piston body reduces the load on the support mechanism, making movement more controllable.

[0016] In one embodiment, a pair of symmetrically arranged lifting lugs are provided on the inner wall of the piston body, and the pair of lifting lugs are located within the projection range of the opening at the tail. This facilitates the insertion of a lifting tool onto the lifting lugs through the tail opening of the piston body to lift the piston. Especially in the application of ultra-large diameter pistons (1500-2400mm), the pair of symmetrically arranged lifting lugs provide a reliable force point for the lifting tool, ensuring the stability of the center of gravity during lifting, so that the piston can be kept in a horizontal state, thereby improving the integrity and protection of the outer peripheral wall and its cladding layer on the piston body.

[0017] Secondly, embodiments of this application also provide a die-casting machine, which includes at least a cylinder liner and the piston, wherein the piston is disposed within the cylinder liner.

[0018] The beneficial effects of the piston and die-casting machine provided in this application are as follows: Compared with the prior art, the piston of this application includes a first outer peripheral portion and a second outer peripheral portion arranged sequentially from the head to the tail of the body, wherein the outer diameter of the first outer peripheral portion is larger than the outer diameter of the second outer peripheral portion, so that the first outer peripheral portion protrudes to form a rodless cavity and a rod cavity region.

[0019] On the one hand, a copper alloy cladding layer is applied to the first outer periphery. Utilizing the low coefficient of friction and good anti-adhesion properties of copper alloy, this fundamentally solves the problem of "adhesive wear (seizing)" that easily occurs between ductile iron pistons and cast iron cylinder liners under extreme conditions. Even under poor lubrication boundary conditions, the copper alloy cladding layer on the first outer periphery can provide good solid lubrication, effectively reducing frictional resistance and wear risk, and improving wear resistance and friction reduction. This helps prevent "cylinder scoring" and "seizing," thereby extending the service life of the piston and cylinder liner. The copper alloy cladding layer on the first outer periphery makes primary contact with the cylinder liner. Utilizing the friction-reducing properties of the copper alloy cladding layer, the protruding first outer periphery can act as a guide ring, effectively solving the problem of traditional ultra-large diameter pistons being prone to wear and failure due to the lack of a guide ring support.

[0020] On the other hand, allowing a gap between the second outer periphery and the cylinder liner reduces the contact pressure between them or allows them to contact only under specific operating conditions. This helps to reduce the total contact area between the piston and the cylinder liner, thus reducing overall frictional power loss. Furthermore, the stainless steel cladding layer on the second outer periphery helps to improve hardness and corrosion resistance, thereby ensuring the overall durability of the piston. Attached Figure Description

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

[0022] Figure 1 A three-dimensional structural diagram of the piston provided in the embodiments of this application. Figure 1 ; Figure 2 This is a schematic diagram of the internal structure of the piston provided in an embodiment of this application; Figure 3 for Figure 2 A partially enlarged structural diagram of part A in the diagram; Figure 4 for Figure 3 A partially enlarged structural diagram of part B in the diagram; Figure 5 A three-dimensional structural diagram of the piston provided in the embodiments of this application. Figure 2 ; Figure 6 A three-dimensional structural diagram of the piston provided in the embodiments of this application. Figure 3 ; Figure 7 A schematic diagram of the orthographic projection of the tail section of the piston provided in an embodiment of this application; Figure 8This is a schematic diagram of the structure of a piston installed inside a die-casting machine cylinder liner, provided in an embodiment of this application. Figure 9 This is a schematic diagram of the internal structure of a piston installed inside a die-casting machine cylinder liner, as provided in an embodiment of this application.

[0023] The following are the labeling elements in the figure: 100-Ontology; 1-Head; 21-First outer periphery; 22-Second outer periphery; 3- Annular groove; 4-Reservoir; 5- Annular boss; 51- Groove; 6-Tail; 61-Opening; 7-Hanging lugs; 8-Cylinder liner; 81-Protrusion. Detailed Implementation

[0024] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0025] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0026] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0027] 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 one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0028] In harsh working conditions such as high temperature and high pressure, ductile iron pistons have insufficient wear resistance, thermal conductivity, and fit with cylinder liners, leading to easy wear and reduced reliability.

[0029] In related technologies, solutions to address the aforementioned problems include surface coating technology, optimized piston structure design, and the use of high-performance sealing materials. However, these methods still have certain limitations. For example, conventional surface coating technology has shortcomings in terms of bonding strength with the piston substrate, coating uniformity, and durability; while optimizing piston structure design can improve the piston's stress conditions to some extent, its effect on improving the piston's wear resistance and corrosion resistance is limited; high-performance sealing materials are expensive, and their sealing performance is still affected by the piston surface condition; the problem of traditional ultra-large diameter pistons (1500-2400mm) being prone to wear and failure under high temperature and high pressure conditions without guide ring support is becoming increasingly serious. Therefore, the solutions adopted by the aforementioned related technologies for piston surface strengthening technology and piston structural design still have shortcomings.

[0030] Therefore, this application provides a novel piston and a die-casting machine using the piston. The piston structure is improved by adding a protruding structure as a guide structure on the outer periphery of the piston and applying different cladding treatments to different parts of the outer periphery. This effectively increases the structural strength, wear resistance, high temperature resistance and corrosion resistance of the piston, which helps to solve the problem of easy wear and failure of traditional ultra-large diameter pistons under high temperature and high pressure conditions due to the lack of guide ring support. The details are described below.

[0031] Please refer to the following: Figure 1 and Figure 2 The piston provided in this application embodiment includes a body 100. The piston body 100 has an appearance similar to a bell cover. The piston body 100 is made of ductile iron (QT600-3), which has stronger weight reduction performance, which is conducive to adapting to large-scale vibration. At the same time, it has more outstanding wear resistance and reduces maintenance costs.

[0032] The piston body 100 includes at least a head 1 and, from the head 1 towards the tail of the body 100, a first outer peripheral portion 21 and a second outer peripheral portion 22, wherein the outer diameter of the first outer peripheral portion 21 is larger than the outer diameter of the second outer peripheral portion 22. This can be understood as, for example... Figure 1 and Figure 2 As shown, on the outer periphery of the body 100, the first outer peripheral portion 21 protrudes outward relative to the second outer peripheral portion 22, forming a rodless cavity and a rod cavity region.

[0033] The first outer peripheral portion 21 is provided with a copper alloy cladding layer (not shown in the figure). Preferably, a 0.7-0.8 mm thick copper alloy cladding layer is laser-clad, and more preferably, a 0.75 mm thick copper alloy cladding layer is laser-clad. The main function of the copper alloy cladding layer on the first outer peripheral portion 21 is to prevent serious failures such as "cylinder scoring" or "seizing," thereby increasing the wear resistance between the piston and cylinder liner and improving the service life of the piston.

[0034] The second outer periphery 22 is provided with a stainless steel cladding layer (not shown in the figure). Preferably, a stainless steel cladding layer with a thickness of 0.2-0.4 mm can be laser-clad, and more preferably, a stainless steel cladding layer with a thickness of 0.3 mm can be laser-clad. The main function of the stainless steel cladding layer on the second outer periphery 22 is to increase wear resistance and rust prevention.

[0035] Compared with the prior art, the piston provided in this application embodiment has a first outer peripheral portion 21 and a second outer peripheral portion 22 arranged sequentially from the head 1 of the body 100 to the tail. The outer diameter of the first outer peripheral portion 21 is larger than the outer diameter of the second outer peripheral portion 22, so that the first outer peripheral portion 21 protrudes to form a rodless cavity and a rod cavity region.

[0036] On the one hand, a copper alloy cladding layer is applied to the first outer periphery 21. Utilizing the low coefficient of friction and good anti-adhesion properties of copper alloy, this fundamentally solves the problem of "adhesive wear (seizing)" that easily occurs between ductile iron pistons and cast iron cylinder liners under extreme conditions. Even under poor lubrication boundary conditions, the copper alloy cladding layer on the first outer periphery 21 can provide good solid lubrication, effectively reducing frictional resistance and wear risk, and improving wear resistance and friction reduction. This helps prevent "cylinder scoring" and "seizing," thereby extending the service life of the piston and cylinder liner.

[0037] Furthermore, the copper alloy cladding layer on the first outer periphery 21 not only reduces friction but also has a thermal conductivity far exceeding that of ductile iron. The heat absorbed by the piston head 1 can be transferred to the cylinder liner through the copper alloy cladding layer on the first outer periphery 21, and then carried away by the cooling system on the cylinder liner. This helps to reduce the piston's operating temperature, alleviate the thermal load, and effectively improve reliability and efficiency.

[0038] In this way, the copper alloy cladding layer on the first outer periphery 21 makes the main contact with the cylinder liner. By utilizing the friction-reducing properties of the copper alloy cladding layer, the protruding first outer periphery 21 can act as an integral, non-detachable high-performance guide ring, effectively solving the problem of easy wear and failure of traditional ultra-large diameter pistons without guide ring support.

[0039] Furthermore, in practical applications, the working environment contact pressure between the second outer peripheral portion 22 and the cylinder liner may be lower than that between the first outer peripheral portion 21 and the cylinder liner, but it may be affected by oscillation, vibration, or corrosion from impurities. Therefore, the stainless steel cladding layer on the second outer peripheral portion 22 helps to improve hardness and corrosion resistance, thereby ensuring the overall durability of the piston.

[0040] As can be seen, the piston structure provided in this application embodiment, through the protruding first outer peripheral portion 21 (with a copper alloy cladding layer thereon) undertaking the main guiding and friction reduction functions, and the combination of the protruding first outer peripheral portion 21 (with a stainless steel cladding layer thereon) undertaking the auxiliary support and wear-resistant protection functions, achieves the effects of extreme friction reduction and anti-galling, efficient heat conduction and load reduction, zoned wear resistance and integrated guiding design, effectively improving the reliability, working efficiency and service life of the piston under harsh working conditions such as high temperature, high pressure, high speed and variable load.

[0041] Regarding the structure on the outer periphery of the piston body 100 in this application embodiment, please refer to one embodiment of this application as well. Figure 2 and Figure 3 At least two adjacent annular grooves 3 are provided on the first outer peripheral portion 21, and the at least two annular grooves 3 are used to install sealing rings (not shown in the figure).

[0042] In this embodiment, at least two coaxial annular grooves 3 are formed on the outer periphery 21 of the piston body 100. The two annular grooves 3 are spaced apart, and sealing rings can be installed on each annular groove 3. The shape and depth of the annular grooves 3 can be set according to the cross-sectional shape of the sealing ring. In this embodiment, a rectangular cross-sectional groove is preferred; in other embodiments, circular or elliptical cross-sectional grooves can also be used, etc., and no specific limitation is made here.

[0043] In this way, by using at least two annular grooves 3 on the first outer peripheral portion 21 to respectively set sealing rings (not shown in the figure), a multi-stage sealing structure is formed on the outer periphery of the piston, which is beneficial to improving the reliability and safety of the entire hydraulic system.

[0044] The area between adjacent seals forms an oil trapping zone, which effectively stores hydraulic oil, ensuring the copper alloy cladding surface remains well lubricated. This avoids dry friction or boundary lubrication issues that may occur during reciprocating motion, enhancing the friction-reducing and anti-galling effects of the copper alloy cladding. The oil trapping zone between adjacent seals also helps balance the pressure on both sides of the piston, resulting in smoother piston movement, reduced vibration and impact, and consequently lowering the risk of abnormal wear.

[0045] Please refer to the embodiments in this application as well. Figure 3 and Figure 4The first outer peripheral portion 21 also has a plurality of liquid storage tanks 4 arranged around the first outer peripheral portion 21, which are used to store hydraulic oil.

[0046] like Figure 4 As shown, a plurality of V-shaped reservoirs 4 are provided on the first outer peripheral portion 21. Each reservoir 4 can store hydraulic oil, which helps to increase the lubrication between the piston and the cylinder liner.

[0047] In this way, multiple V-shaped reservoirs 4 form evenly distributed oil storage points on the outer circumferential surface of the piston. During the reciprocating motion of the piston, these reservoirs 4 can scrape and store a small amount of hydraulic oil. At moments when the oil film may thin after system startup, low-speed operation, sudden load changes, or long-term operation, the main oil film on the piston may not be fully formed. At this time, the hydraulic oil stored in these reservoirs 4 can be released, forming a localized oil film between the contact surfaces, effectively replenishing lubrication and preventing direct contact between the copper alloy cladding layer on the first outer circumference 21 and the cylinder liner.

[0048] In addition, the copper alloy itself has anti-friction properties. When combined with the hydraulic oil continuously supplied in the reservoir 4, it forms a double insurance of solid lubrication and fluid lubrication, effectively reducing the risk of cylinder scoring or seizure.

[0049] In practical applications, after the sealing ring is installed on the annular groove 3 of the piston, the sealing ring will scrape the oil film on the cylinder wall, which will make the oil film thickness on both sides of the sealing ring thinner, thus making it easy for poor lubrication or the formation of a weak lubrication area with dry friction.

[0050] Therefore, please refer to the embodiments in this application as well. Figure 3 and Figure 5 The aforementioned multiple liquid storage tanks 4 are arranged at intervals on the first outer periphery 21 and are evenly distributed on both sides of the at least two annular grooves 3.

[0051] Thus, these reservoirs 4 are evenly distributed on both sides of the annular groove 3 used to install the sealing ring, thereby forming an oil replenishment zone on the weak lubrication areas on both sides of the sealing ring. When the piston moves, the reservoir 4 located in front of the sealing ring (on the side closer to the piston head 1) can replenish hydraulic oil in advance; the reservoir 4 located behind the sealing ring (on the other side away from the piston head 1) can replenish oil to the surface that has just been scraped by the sealing ring, and re-establish the lubricating oil film.

[0052] As can be seen, the multiple liquid reservoirs 4 on the first outer periphery 21 are evenly distributed on both sides of the annular groove 3 used for installing the sealing ring, effectively ensuring the working environment of the sealing ring. This allows the sealing ring to work under good lubrication, significantly reducing friction, wear, and heat generation. This not only extends the service life of the sealing ring but also reduces the possibility of leakage due to abnormal wear in the sealing ring area.

[0053] Regarding the structure on the head 1 of the piston body 100, in one embodiment of this application, please refer to... Figure 5 The head 1 is provided with an annular boss 5 arranged around the center point of the head 1. The function of the annular boss 5 is to play a positioning role during the processing and clamping of the piston, and to facilitate the placement of the piston on the carrier during the piston transfer process.

[0054] In this embodiment, the annular boss 5 protrudes from the surface of the head 1 of the piston body 100 and is arranged around the center point of the piston head 1. The size of the annular boss 5 can be set according to the clamping requirements and the object, and is not specifically limited here.

[0055] Preferably, such as Figure 2 and Figure 5 As shown, on the piston body 100 provided in this application embodiment, the head 1 end face outside the annular boss 5 is gradually inclined to its outer edge, so that the surface of the piston head 1 forms an inclined surface extending to the outer edge of the head 1.

[0056] Thus, during the high-speed movement of the piston, the inclined surface on the piston head 1 helps to improve the flow characteristics of the oil, allowing the oil on the piston head 1 to flow smoothly and diffuse evenly to the outer edge of the head 1, and smoothly reach the outer periphery of the piston, effectively reducing the turbulence and vortex of the hydraulic oil.

[0057] In addition, changing the surface profile from the annular boss 5 on the piston head 1 to the outer edge of the piston to a smooth inclined transition helps to evenly distribute stress, avoid stress concentration, effectively improve the structural integrity and fatigue resistance of the piston head 1, make it more durable under high pressure conditions, and thus reduce the risk of cracking of the piston head 1.

[0058] In practical applications, at the moment the hydraulic cylinder begins to work, the cavity on one side of the piston needs to be quickly filled with hydraulic oil in order to build up pressure and drive the piston to move. If the oil fails to reach the desired position immediately, a brief "idle stroke" or "response delay" will occur, which is extremely detrimental to systems requiring precise control (such as servo hydraulics and micro-motion operation of engineering machinery).

[0059] Therefore, in another embodiment of this application, please refer to Figure 5 The piston head 1 provided in this embodiment also has a groove 51 located in the annular boss 5. The groove 51 is used to store hydraulic oil, which is beneficial for the cylinder to respond quickly when it is working.

[0060] In this embodiment, the piston head 1 has an annular boss 5 arranged around the center point of the head 1, so that a circular oil storage groove 51 is formed in the annular boss 5.

[0061] Thus, the groove 51 on the piston head 1 serves as a built-in oil reservoir located at the forefront of the action. At the instant the hydraulic valve opens, oil can immediately gush out from the groove 51, quickly filling the space between the piston end and the cylinder liner, effectively shortening the pressure build-up time, enabling the piston to start quickly, thereby improving the response speed of the entire hydraulic system and enhancing the smoothness of motion under low-speed conditions.

[0062] In practical applications, the biggest concern in ductile iron piston casting is uneven wall thickness. Thick sections cool slowly, making them prone to internal defects such as shrinkage cavities and porosity, which severely affect the mechanical properties of the casting.

[0063] Therefore, regarding the internal structure of the piston body 100 provided in the embodiments of this application, please refer to one embodiment of this application. Figure 6 and Figure 7 The piston body 100 is hollowed out so that the tail 6 of the body 100 has an opening 61 that connects to the interior of the body 100.

[0064] The hollowing out of the piston body 100 helps to make the casting wall thickness uniform, reduce casting defects, and reduce costs and weight.

[0065] Therefore, the piston is designed as a hollow structure, which makes the wall thickness of the casting as consistent as possible, effectively reducing the risk of casting defects and ensuring the internal quality of the piston body 100 from the source of manufacturing.

[0066] In addition, the piston body 100 is hollowed out to reduce the piston's mass. This means that the reciprocating inertial force of the piston is reduced, thus reducing vibration and noise in the hydraulic system. Especially in the application of ultra-large diameter pistons (1500-2400mm), the lightweight piston body 100 can reduce the load on its support mechanism, making the movement more controllable.

[0067] Based on the above, please refer to the embodiments in this application as well. Figure 6 and Figure 7 The inner wall of the piston body 100 is provided with a pair of symmetrically arranged lifting lugs 7, which facilitates the insertion of a lifting tool into the lifting lugs 7 through the opening 61 at the tail 6 of the piston body 100 to lift the piston.

[0068] Especially in the application of ultra-large diameter pistons (1500-2400mm), a pair of symmetrically arranged lifting lugs 7 provide a reliable force point for lifting tools (such as lifting beams and special clamps). The symmetrical arrangement of the pair of lifting lugs 7 ensures the stability of the center of gravity during lifting, so that the piston can be kept in a horizontal position, avoiding bumps and scratches caused by tilting, thereby improving the integrity and protection of the outer peripheral wall and its cladding layer on the piston body 100.

[0069] In addition, since the piston body 100 in this embodiment has a hollowed-out structure, it provides space and mounting wall for the lifting lug 7 without adding any extra external parts, thus effectively improving space utilization.

[0070] The pair of lifting lugs 7 are located within the projection range of the opening 61 at the tail 6, which means that the operator can operate directly from the opening 61 at the tail 6 and easily install lifting tools (such as wire ropes and hooks) onto the lifting lugs 7, thereby improving installation efficiency.

[0071] Regarding the piston manufacturing process provided in the embodiments of this application: The production plan includes three steps in sequence: substrate pretreatment, laser cladding, and post-treatment. The specific processes for each step are as follows: (1) Substrate pretreatment The purpose of substrate pretreatment is to remove impurities such as oil and rust from the surface of the ductile iron (QT600-3) piston, while roughening the surface, increasing the contact area between the substrate and the cladding powder, and improving the bonding strength of the cladding layer. The specific steps are as follows: Machining: The areas to be clad (skirt, ring groove, etc.) of the QT600-3 ductile iron piston are preliminarily turned or ground to remove oxide scale and fatigue layer, ensuring the basic dimensions. Usually, a cladding allowance of 0.5-1.0 mm is reserved.

[0072] Cleaning and purification: An alkaline degreasing agent (main components are sodium hydroxide, sodium carbonate, and sodium phosphate in a mass ratio of 3:2:1) is used to immerse the ductile iron (QT600-3) piston in a degreasing agent solution at 50-60℃ for 15-20 minutes. The alkaline degreasing agent removes animal and vegetable oils from the piston surface through saponification and removes mineral oil through emulsification, ensuring thorough removal of surface oil stains.

[0073] Surface roughening: Sandblasting is employed, using white corundum (high hardness, sharp edges, and good roughening effect) as the blasting medium, with a particle size of 80-120 mesh and a blasting pressure of 0.4-0.6 MPa. During sandblasting, the piston is fixed on a rotating worktable, rotating at a uniform speed to ensure uniform surface roughening, ultimately achieving a surface roughness Ra of 5-12.5 μm. The roughened surface forms an uneven "anchoring" structure, improving laser absorption and providing a good mechanical bonding foundation for the cladding layer. After sandblasting, the surface is cleaned again with alcohol and quickly dried to prevent secondary oxidation.

[0074] (2) Laser cladding Laser cladding is a key step in forming a metallurgical bond between copper-based cladding powder and the surface of a ductile iron (QT600-3) piston. In this embodiment, a semiconductor laser is preferably used. By optimizing process parameters, the quality of the cladding layer is ensured to be stable. The specific process is as follows: Equipment selection: A semiconductor laser with a rated power of 3000W and a wavelength of 976nm±10nm is used. The laser beam has good quality and uniform energy density, which is suitable for metal surface cladding. The powder feeding equipment is a coaxial powder feeder with a powder feeding accuracy of ±0.5g / min, which can ensure that the cladding powder is uniformly delivered to the laser action area. Cladding operation: The pretreated ductile iron (QT600-3) piston is fixed on the CNC worktable. The worktable drives the piston to rotate at a constant speed (0.5-1 r / min). The laser head moves at a constant speed along the piston axis (matching the scanning speed). The powder feeder delivers copper-based cladding powder to the laser action area through a coaxial powder feeding nozzle, forming a continuous and uniform cladding layer. During the cladding process, the state of the molten pool is monitored in real time, and the process parameters are finely adjusted through the CNC system to ensure that the cladding layer is free of porosity and cracks.

[0075] (3) Post-processing Post-processing includes stress-relief annealing and surface finishing, the purpose of which is to eliminate internal stress in the cladding layer and improve surface precision. The specific processes are as follows: Slow cooling or annealing: After the cladding is completed, the workpiece is immediately placed in a preheated furnace or insulation cotton at 250-350℃ to slowly cool to room temperature, or directly subjected to stress-relief annealing (holding at 500-580℃ for 1-2 hours, then cooling in the furnace to below 300℃ and air cooling) to eliminate residual stress.

[0076] Machining: The cladding layer is machined to the required dimensional accuracy using precision turning and finishing methods.

[0077] Surface finishing: Abrasive wheel grinding is employed with a grit size of 240-320 mesh, a grinding speed of 15-20 m / s, and a feed rate of 0.01-0.02 mm / r. Emulsion cooling is used during grinding to prevent surface overheating; ultimately, the piston surface roughness is controlled to Ra≤0.8μm to meet assembly accuracy requirements.

[0078] Specific applications of the pistons provided in the embodiments of this application: The piston of this application embodiment can be widely used in high-pressure cylinders in high-load internal combustion engines and die-casting machines. As an example, this piston can be applied to high-load internal combustion engines with a displacement of 2.0-3.0L, including: Commercial vehicle internal combustion engines: such as diesel internal combustion engines for heavy-duty trucks and buses. These internal combustion engines have high working loads (maximum power 150-250kW), and the pistons need to withstand high temperature, high pressure and high frequency friction for a long time. Internal combustion engines for construction machinery: such as internal combustion engines for excavators and loaders. These internal combustion engines operate under complex conditions and are often in full-load operation, which places extremely high demands on the wear resistance of the pistons. Special vehicle internal combustion engines: such as those used in off-road vehicles and military vehicles. These internal combustion engines need to be able to withstand harsh environments (such as high temperatures and dust), and the pistons need to have good corrosion resistance and reliability.

[0079] High-pressure hydraulic cylinders in the die casting machine industry: such as high-pressure hydraulic cylinders with locking piston diameter (1500-2400mm), no guide ring support, high pressure (16-31.5MPa), which requires extremely high wear resistance of the piston.

[0080] Please refer to the following: Figure 8 and Figure 9 This application also provides a die-casting machine, which includes at least a cylinder liner 8 and a piston according to this application embodiment, wherein the piston body 100 is disposed inside the cylinder liner 8.

[0081] In this embodiment, as Figure 9 As shown, the cylinder liner 8 has a protrusion 81 that mates with the piston head 1, and this protrusion 81 corresponds to the position of the annular boss 5 on the piston head 1. This allows the hydraulic oil in the groove 51 of the annular boss 5 to fill the space between the protrusion 81 and the piston front end, effectively shortening the pressure build-up time and enabling the piston to start quickly. This improves the response speed of the entire die-casting system and enhances the smoothness of motion under low-speed conditions.

[0082] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A piston, characterized in that, include: The body includes a head and, from the head toward the tail of the body, a first outer peripheral portion and a second outer peripheral portion; wherein, the outer diameter of the first outer peripheral portion is larger than the outer diameter of the second outer peripheral portion, so that the first outer peripheral portion protrudes outward on the outer periphery of the body; the first outer peripheral portion is provided with a copper alloy cladding layer, and the second outer peripheral portion is provided with a stainless steel cladding layer.

2. The piston according to claim 1, characterized in that: The first outer peripheral portion has at least two adjacent annular grooves, which are used to install sealing rings.

3. The piston according to claim 2, characterized in that: The first outer peripheral portion also has a plurality of liquid storage tanks arranged around the first outer peripheral portion, the plurality of liquid storage tanks being used to store hydraulic oil.

4. The piston according to claim 3, characterized in that: The plurality of liquid storage tanks are arranged at intervals on the first outer periphery and are evenly distributed on both sides of the at least two annular grooves.

5. The piston according to claim 1, characterized in that: The head is provided with an annular protrusion arranged around the center point of the head.

6. The piston according to claim 5, characterized in that: The head also has a groove located within the annular boss, the groove being used to store hydraulic oil.

7. The piston according to claim 5, characterized in that: The head end face, excluding the annular boss, is gradually inclined at its outer edge.

8. The piston according to any one of claims 1 to 7, characterized in that: The interior of the body is hollowed out, so that the tail of the body has an opening that connects to the interior of the body.

9. The piston according to claim 8, characterized in that: The inner wall of the main body is provided with a pair of symmetrically arranged lifting lugs, which are located within the projection range of the opening at the tail.

10. A die-casting machine, characterized in that: It includes at least a cylinder liner and a piston as described in any one of claims 1 to 9, the piston being disposed within the cylinder liner.

Images