In the vast system of construction machinery, the track roller is a crucial 'foundation stone' beneath the wheels. As a core component of tracked machinery like excavators and bulldozers, it not only supports the weight of the machinery but also transmits driving force under complex conditions, while enduring various impacts and frictions from the ground. The performance of the track roller is vital for the efficient operation and long-lasting life of construction machinery. Today, we will delve into the manufacturing process behind the scenes, detailing how the production process of the track roller transforms raw materials into a reliable 'companion' of construction machinery.
1. Material selection: laying the foundation for excellent performance
The selection of materials is the first step in the production of track rollers, which directly determines their final performance and service life. In the field of construction machinery parts manufacturing, the commonly used materials of track rollers mainly include alloy structural steel, such as 50Mn, 40Cr, etc.
• 50Mn steel yield strength is more than 645MPa, tensile strength is more than 835MPa, with good strength and wear resistance, suitable for use in medium load and wear environment;
• 40Cr steel after tempering treatment yields a strength is more than 785MPa, tensile strength is more than 980MPa, excellent comprehensive mechanical properties, suitable for bearing large loads and complex stress conditions;
When selecting materials, it is essential to consider not only the material's inherent properties but also the specific application scenarios and operational requirements of the track roller. This ensures that the chosen materials meet the demands for strength, wear resistance, and corrosion resistance. Additionally, the quality inspection of raw materials is crucial, including chemical composition analysis and mechanical performance testing. Only materials that meet the standards can proceed to the subsequent production stages.
2. Casting or forging: shaping the prototype of the Track Roller
According to the structure and performance requirements of the track roller,the casting or forging process can be used to manufacture the blank.
(1) Casting process
For the complex structure of the track roller body, the casting process is usually used. The common casting methods are sand casting and metal casting: (among which, sand casting is divided into artificial sand casting and mechanical sand casting)
• The melting temperature of sand casting is controlled at 1550-1600℃ (carbon steel material), the pouring speed is 5-8kg/s, and the cooling time is set to 4-8 hours according to the size of the workpiece, to ensure that the internal structure of the blank is uniform and there are no obvious defects such as pores and cracks on the surface of the product;
• Metal casting is preheated to 200-300℃ through the mold, which improves the size accuracy of the blank and reduces the surface roughness. The production efficiency is more than 30% higher than that of sand casting.
• Compared with artificial sand casting, mechanical sand casting is more efficient, and the residual sand on the surface of the products after mechanical sand casting is easier to remove; the beauty of the product will also be improved.
(2) Forging process
Forging is a better choice for the track roller shaft that can withstand high load:
• In the process of die forging, the blank is heated to 1150-1200℃ and formed under a press of 8000-10000 tons. The size accuracy of the blank can reach ±0.5mm and the performance can be improved by 20%.
3. Mechanical finishing: give the product a precise size and good performance
After the rough manufacturing is completed, mechanical finishing is required to achieve the dimensional accuracy and surface quality required by the design.
(1) Rough processing
Turning machines, milling machines, and other equipment are used to remove the allowance on the surface of the blank. The allowance for rough machining of the outer circle of the wheel body is 3-5mm, the allowance for the inner hole is 2-3mm, and the allowance for the end face is 1-2mm to ensure the stability of the reference for subsequent finishing.
(2) High-temperature cleaning
• The outer circle of the wheel is cleaned by high-temperature cleaning equipment to wash away the residues left on the surface after rough processing.
• The length of high-temperature cleaning depends on the material, mass, and weight of the track roller.
(3)Modulation processing
• Other manufacturers' roller modulation process is half of the wheel body separately modulation; while our company strictly adopts the whole track roller overall modulation treatment, which makes the track roller always maintain a high level of concentricity value, and thus increases the durability and service life of the product.
• For different products, select different modulation equipment to make the product finish strictly meet the requirements (standard: the surface finish of the track roller is below 3.2).
4. Heat treatment: the key process to improve performance
(1) Annealing and normalizing
The casting blank is annealed at 550-650℃ (holding for 4-6 hours) to eliminate internal stress, reduce the hardness to 180- 220HB, and improve the machining performance; the forging blank is normalized at 900-950℃ (holding for 2-3 hours) to increase the hardness to 220-250HB.
(2) quenching and tempering
• Quenching process heats the parts to 850-880℃ (40Cr steel), keeps it for 1-1.5 hours, and then uses oil cooling or water cooling to cool quickly, so that the surface hardness reaches HRC50-55;
• After quenching, it needs to be tempered at 200℃ for 2 hours to eliminate internal stress and control the final hardness at HRC45-60.
5. Surface treatment: enhance corrosion resistance and wear resistance
Common surface treatment methods and technical parameters:
• Surface quenching: Induction heating temperature 850-900℃, hardened layer depth 2-3mm, surface hardness HRC55-60, suitable for key stressed parts of shaft components.
6. Quality testing: control the product quality throughout the whole process
(1) Raw material testing
• Chemical composition analysis: using a direct reading spectrometer, the detection accuracy reaches 0.01% (such as carbon content detection error ≤±0.005%).
(2) Process detection
• The casting blank must be free of cracks, and burrs and flash must be completely removed. The surface roughness of the product must meet the standard data requirements. In the machining area, defects such as pores, sand holes, and slag must not exceed 1mm in size; for machining areas with a thickness of less than 1mm, the number of defects on one side must be no more than 5 (not concentrated).
• After heat treatment, the Rockwell hardness meter (HRC scale) is used to detect, the sampling rate of each batch is greater than or equal to 5%, and the hardness fluctuation range is less than or equal to ±2HRC.
• Our advantages: In the production of track rollers, after conventional heat treatment, the surface hardness layer of the track rollers will reach 3-4, 4-5, 5-6mm, depending on the machine model. However, ordinary manufacturers only have a thin layer of hardness of about 2mm on the surface, which is more wear-resistant.
Summary: Professional technology to achieve reliable quality
From material selection to quality inspection, every link embodies the professional wisdom and exquisite technology of mechanical manufacturing. The production process of the track roller is complex and rigorous, and each step has an important impact on the performance and quality of finished products.
In the field of construction machinery parts manufacturing, quality control and continuous improvement are the key to the survival and development of enterprises. We always adhere to the strict control of every production link, constantly optimize the process parameters, improve the level of production technology, and devote ourselves to providing customers with high-quality track roller products.
If you have any questions or need information about the production process of the track roller or our products, please feel free to contact us (binochen@yintparts.com) at any time. We will provide you with satisfactory solutions with professional knowledge and quality service. Follow us for more professional knowledge of construction machinery parts manufacturing!