Machining process for piston rod of hydraulic oil cylinder

Abstract

The invention relates to a piston rod manufacturing process method, in particular to a hydraulic oil cylinder piston rod machining process. A semi-finished product of the end part of the piston rod is firstly processed. The method further comprises the following steps: S1, blanking; s4, cladding, S5, semi-finish turning, S6, copper welding, S7, grinding, S8, finish turning and S9, polishing are carried out, and the finished piston rod is formed. The steel plates are adopted to replace forgings, the cost is reduced, the abrasion resistance of the piston rod can be improved, and the surface hardness of the piston rod can meet the use requirement.

Description

Technical Field

[0001] This invention relates to a process for manufacturing piston rods, and more particularly to a process for machining piston rods for hydraulic cylinders. Background Technology

[0002] Currently, hydraulic cylinder piston rods are typically made from forgings, which are usually made of high-quality alloy steel. The raw material price is high, especially when manufacturing large hydraulic cylinders, where the required forgings are large in size and weight, leading to a significant increase in raw material costs. Furthermore, the forging process requires multiple forging and heat treatment processes, which not only increase processing costs but also consume a large amount of energy. The forging process generates a large amount of waste (such as flash and chips), resulting in low material utilization and further increasing costs. After forging, the piston rod forging surface needs to be electroplated, resulting in a thin coating, typically a few micrometers to tens of micrometers. The coating is physically bonded to the piston rod, resulting in low bonding strength and uneven coating thickness, affecting the quality and appearance of the piston rod.

[0003] Therefore, in view of the above-mentioned technical problems and defects, the present invention proposes a hydraulic cylinder piston rod processing technology, which uses steel plate instead of forgings to reduce costs, not only improves the wear resistance of the piston rod, but also makes the surface hardness of the piston rod meet the requirements for use. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art and to propose a hydraulic cylinder piston rod processing technology.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A hydraulic cylinder piston rod machining process, which first processes a semi-finished piston rod end, also includes the following steps: S1: Material feeding; S2: Rolling, rolling steel plates into a ring shape; S3: Welding, welding the annular butt joint to form the piston rod rod part; welding the piston rod end to the piston rod rod part to form the piston rod base; S4: Cladding, cladding is performed on the outer surface of the piston rod portion of the piston rod substrate to form a reinforced piston rod substrate; S5: Semi-finish turning, semi-finish turning of the reinforced piston rod substrate to remove burrs and uneven parts; S6: Copper welding, welding a copper ring layer to the end of the piston rod; S7: Grinding, grinding of the reinforced piston rod substrate after copper welding; S8: Fine turning, the piston rod end is finely turned to produce at least one sealing groove to form a piston rod blank; S9: Polishing to form the finished piston rod.

[0006] Furthermore, the raw material for cutting in S1 is Q355 steel plate.

[0007] Furthermore, in step S2, the steel plate needs to be preheated to 100-150°C before rolling.

[0008] Furthermore, in step S4, the piston rod substrate is pretreated and preheated before cladding, with the preheating temperature being 80-180℃.

[0009] Furthermore, in S4, the cladding powder is an iron-based alloy, the powder feeding rate is 30-45 g / min, the cladding speed is 8-12 mm / s, and the cladding layer thickness is 3-5 mm.

[0010] Furthermore, in S6, annular grooves are machined at both ends of the piston rod, and copper is welded into the annular grooves.

[0011] Furthermore, the height of the copper ring layer is ensured to be 1 mm higher than the top of the annular groove.

[0012] Furthermore, in S8, the sealing groove has a width of 2-10mm and a depth of 1-5mm.

[0013] Compared with existing technologies, the advantages of this invention are: 1. Cost-saving: Made of hollow steel plates, which saves costs compared to using forgings; 2. Piston Rod Surface: The surface of the piston rod is treated by cladding. Cladding involves melting the piston rod surface at high temperature to form a metallurgical bond with high bonding strength. The cladding coating can form a relatively thick coating (0.5-5mm) in one go, which can reach more than 70% of the surface strength of the piston rod, making the surface hardness of the piston rod reach about HRC40-50. 3. It has a good effect on environmental protection. The cladding does not require the use of toxic chemicals such as cyanide and chromic acid, reducing wastewater and exhaust gas pollution, greatly improving the factory workshop environment, and also greatly benefiting operators. It can reduce environmental protection costs and contribute to sustainable development. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a schematic diagram of the steel plate rolling process of the present invention; Figure 3 A schematic diagram showing the piston rod section and piston rod base after welding; Figure 4 Schematic diagram of the piston rod substrate after copper welding to strengthen it; Figure 5 This is a schematic diagram of the finished product; In the diagram: 1. Circular shape, 11. Butt joint, 2. Piston rod end, 21. Annular groove, 22. Copper ring layer, 3. Piston rod part, 4. Piston rod base, 5. Sealing groove. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1, referring to Figures 1-5 A hydraulic cylinder piston rod machining process includes the following steps: S1: Material feeding; S2: Rolling, rolling the steel plate into a ring shape 1; S3: Welding, welding the butt joint 11 of the annular 1 to form the piston rod part 3; welding the piston rod end 2 to the piston rod part 3 to form the piston rod base 4; S4: Cladding, cladding is performed on the outer surface of the piston rod portion 3 of the piston rod substrate 4 to form a reinforced piston rod substrate; S5: Semi-finish turning, semi-finish turning of the reinforced piston rod substrate to remove burrs and uneven parts; S6: Weld copper, weld a copper ring layer 22 to the piston rod end 2; S7: Grinding, grinding of the reinforced piston rod substrate after copper welding; S8: Fine machining, the piston rod end 2 is fine machined to produce at least one sealing groove 5, forming a piston rod blank; S9: Polishing to form the finished piston rod.

[0017] This technical solution avoids the use of traditional forging methods to manufacture forgings and then process piston rods. This invention uses steel plates to directly roll into piston rod part 3, and then welds piston rod end 2 to piston rod part 3 to form piston rod base 4, which can effectively reduce costs. Then, through cladding treatment, without using traditional electroplating process, the surface hardness and bonding strength of piston rod base 4 are enhanced. Finally, multiple sealing grooves 5 are processed on piston rod end 2, and after polishing, the final piston rod product is formed.

[0018] This invention has wide applicability; different cylinders can be cut from steel plates of varying thicknesses. For example, light-duty hydraulic cylinders can use steel plates with a thickness of 10-25mm, while servo cylinders can use steel plates with a thickness of 8-20mm. During material cutting, a laser cutting machine or a flame cutting machine can be used to cut the raw material. The cutting size can be determined based on the inner diameter of the cylinder to establish the required piston rod size, which is then calculated. In this embodiment, the raw material for cutting in step S1 is Q355 steel plate. After the material is cut, the steel plate is rolled up using a rolling machine. The rolling machine can be any existing technology. Before rolling, the steel plate needs to be preheated to 100-150℃. In actual operation, steel plates of 40mm and below do not need to be heated, while steel plates larger than 40mm need to be heated to 100-150℃.

[0019] After the coiling machine rolls the steel plate, refer to Figure 2 The butt joint 11 at both ends of the steel plate can be welded using autogenous welding. The welding wire can be any one of ER50-6, ER55-G, H08Mn2SiA, or H10Mn2, protected by a CO2 or Ar+CO2 mixed gas. After welding, a rolling process can be used to flatten the butt weld, applying high pressure to the weld surface to reduce the surface roughness to below Ra 0.4μm. (Refer to...) Figure 3 Next, the processed piston rod portion 3 and piston rod end 2 are welded together, ensuring concentricity. This welding forms the piston rod base 4. The weld between the piston rod portion 3 and piston rod end 2 can also be processed using a rolling process. The piston rod portion 3, after rolling, is internally hollow, reducing the overall weight of the equipment, improving its flexibility and energy efficiency, and saving material costs. In some embodiments, the steel plate thickness can be increased to ensure its load-bearing capacity meets actual requirements.

[0020] The next step is S4: cladding treatment. The cladding process includes: a) pretreatment, b) preheating, and c) cladding.

[0021] a. Pre-treatment: Cleaning the surface of the piston rod substrate 4 can improve the bonding strength of the cladding layer. The cleaning method should be selected according to the actual situation. For example, an anhydrous ethanol (alcohol) or isopropanol (IPA) can be used to moisten a lint-free cloth and wipe the surface of the piston rod substrate 4 to remove grease and dust. Alternatively, a sandblasting machine can be used with appropriate abrasives (such as steel grit, alumina grit, etc.) to sandblast the substrate surface. Sandblasting can quickly remove rust, scale, and dirt from the surface, while roughening the surface and increasing the adhesion of the cladding layer.

[0022] b. Preheating: The piston rod base 4 after surface cleaning is preheated at a temperature of 80-180℃. The preheating temperature also depends on the thickness and material of the steel plate. In this embodiment, if the thickness of the Q355 workpiece is 30mm, the preheating temperature is 150-170℃; if the thickness of the Q355 workpiece is 10mm, the preheating temperature is 100-120℃.

[0023] c. cladding: The piston rod base 4 is then transferred to a cladding device for clamping. In this embodiment, cladding is performed only on the surface of the piston rod portion 3 in the piston rod base 4.

[0024] The cladding powder can be a high-hardness, wear-resistant, and corrosion-resistant iron-based alloy, such as 3Cr13 or FeCr, FeCrNi, FeCrMo series powders, etc., with a hardness of HRC40-60 after cladding. It is also wear-resistant and corrosion-resistant. In this embodiment, 3Cr13 powder is preferred. The specific process parameters during cladding are as follows: powder feed rate 30-45 g / min, cladding speed 8-12 mm / s, and cladding layer thickness 3-5 mm.

[0025] After cladding, the piston rod portion 3 effectively resists wear and improves its wear resistance. A dense protective layer is formed on the outer surface of the piston rod portion 3, isolating it from corrosive media. It also enhances the surface hardness of the piston rod portion 3, ultimately improving the piston rod's compressive and impact resistance during operation within the cylinder. A strong metallurgical bond is formed between the cladding layer and the piston rod portion 3, improving not only the surface properties but also the overall performance of the piston rod portion 3. Cooling is performed after cladding, using air cooling, spray cooling, or traditional air cooling. After cladding, a reinforced piston rod substrate is formed.

[0026] Then proceed to step S5, semi-finish turning, to semi-finish turn the reinforced piston rod substrate to remove burrs and uneven parts; In the S6 copper soldering step, refer to Figure 4 The process involves welding copper to the piston rod end 2 within the reinforced piston rod substrate. Annular grooves 21 are machined at both ends of the piston rod end 2, and a copper ring layer 22 is welded within these grooves. The height of the copper ring layer 22 is 1 mm higher than the annular groove 21, and the annular groove 21 is concentric with the reinforced piston rod substrate. The copper welding within the annular groove 21 serves to guide the piston rod as it moves within the hydraulic cylinder.

[0027] Copper has excellent thermal conductivity, preventing overheating. When the piston rod moves within the cylinder, it generates heat. The brazed copper on the piston rod end 2 quickly conducts the high temperature of the piston rod to the cooling system (such as a water jacket or oil passage), preventing material softening or deformation caused by localized overheating. Copper also improves wear resistance, extending piston rod life. Its softness reduces hard friction with the cylinder wall, lowering the wear rate. Furthermore, copper provides plastic deformation compensation; its ductility (elongation > 30%) fills microscopic irregularities, improving the seal between the piston rod end 2 and the cylinder, reducing gas leakage or fluid leakage.

[0028] Before welding the copper, the surface of the reinforced piston rod substrate is cleaned to ensure that there are no impurities on the surface. Welding methods include brazing, TIG welding, laser welding, and MIG welding. Since it involves welding different metals, TIG welding is preferred. Tungsten inert gas (TIG) welding is used. A special fixture is used to fix the reinforced piston rod substrate, ensuring that the copper material and the piston rod end 2 are tightly fitted with a gap ≤0.1mm. During welding, welding begins from the bottom of the annular groove 21, building up to a height of 2-2.5mm, leaving machining allowance. After the copper ring layer 22 is welded, it is slowly cooled to room temperature in air.

[0029] In this embodiment, the welded copper ring layer 22 needs to have a certain thickness to cope with long-term frictional wear. The copper ring layer 22 is welded from the bottom of the annular groove 21, with a total welding height of 2.5 mm. The machining depth of the annular groove 21 is 1 mm. Therefore, after welding, the copper ring layer 22 will protrude 1.5 mm from the top of the annular groove 21. This 1.5 mm protrusion (i.e., the reserved wear-resistant layer) can ensure that the copper ring can withstand wear for up to 10 years. 6 Even with wear during reciprocating motion, its effective thickness remains no less than 0.5mm, thus preventing seal failure due to excessive wear.

[0030] In step S7, the piston rod portion 3 after cladding is precision ground to ensure the dimensional accuracy and surface roughness requirements of the piston rod. CBN grinding wheels are preferred for grinding, with the wheel speed controlled at 25-45 m / s and the single grinding depth set between 0.001 and 0.05 mm. Sufficient cooling is used to control the temperature of the grinding zone at 20-40℃ to prevent thermal damage.

[0031] In step S8, after the copper ring layer 22 to be welded cools to room temperature, the piston rod end 2 is precision machined. The precision machining consists of two steps: First, the copper ring layer 22 is precision machined to its final dimensions, even if its upper surface is 1mm higher than the top of the annular groove 21 (this means the final thickness of the copper ring layer is: 1mm groove depth + 1mm protrusion = 2mm). This final thickness of 2mm ensures that, after allowing for wear, its effective wear-resistant thickness is always ≥0.5mm.

[0032] Then, the sealing groove 5 is precision machined: the sealing groove 5 is precision machined in the area between the copper ring layers. The size of the sealing groove is determined according to the working pressure and the size of the hydraulic cylinder, and its width is usually 2-10mm, and its depth is usually 1-5mm. In this embodiment, the width of the sealing groove 5 is precision machined to 6mm, and the depth is precision machined to 2mm.

[0033] In step S9, the piston rod blank formed in step S8 is polished, such as... Figure 5 As shown, the finished piston rod is obtained. Polishing can be carried out using existing technology, and the surface finish of the piston rod must be Ra0.8.

[0034] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A machining process for a hydraulic cylinder piston rod, characterized in that, First, machine the piston rod end (2), and then... Includes the following steps: S1: Material feeding; S2: Rolling, rolling the steel plate into a ring shape (1); S3: Welding, welding the butt joint (11) of the annular (1) to form the piston rod rod part (3); welding the piston rod end (2) to the piston rod rod part (3) to form the piston rod base (4). S4: cladding, cladding treatment is performed on the outer surface of the piston rod part (3) of the piston rod substrate (4) to form a reinforced piston rod substrate; S5: Semi-finish turning, semi-finish turning of the reinforced piston rod substrate to remove burrs and uneven parts; S6: Weld copper, weld a copper ring layer (22) to the piston rod end (2); S7: Grinding, grinding of the reinforced piston rod substrate after copper welding; S8: Fine machining, the piston rod end (2) is fine machined to produce at least one sealing groove (5) to form a piston rod blank; S9: Polishing to form the finished piston rod.

2. The hydraulic cylinder piston rod machining process according to claim 1, characterized in that, The raw material for cutting in S1 is Q355 steel plate.

3. The hydraulic cylinder piston rod machining process according to claim 1, characterized in that, In step S2, the steel plate needs to be preheated to 100-150°C before rolling.

4. The hydraulic cylinder piston rod machining process according to claim 1, characterized in that, In S4, the piston rod base (3) is pretreated and preheated before cladding, with a preheating temperature of 80-180℃.

5. The hydraulic cylinder piston rod machining process according to claim 1, characterized in that, In step S4, the cladding powder is an iron-based alloy, the powder feeding rate is 30-45 g / min, the cladding speed is 8-12 mm / s, and the cladding layer thickness is 3-5 mm.

6. The hydraulic cylinder piston rod machining process according to claim 1, characterized in that, In the S6, the piston rod end (2) has annular grooves (21) at both ends, and a copper ring layer (22) is welded in the annular grooves (21).

7. The hydraulic cylinder piston rod machining process according to claim 6, characterized in that, Ensure that the height of the copper ring layer (22) is 1 mm higher than the top of the annular groove (21).

8. The hydraulic cylinder piston rod machining process according to claim 1, characterized in that, In S8, the sealing groove (5) has a width of 2-10mm and a depth of 1-5mm.

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