Customizing the output gears of automotive seats is a multifaceted project involving materials science, precision manufacturing, and quality control. Its core lies in achieving efficient, stable, and durable gears in transmission systems through scientific material selection, sophisticated processing, and strict quality control. The following details the four dimensions of material selection, processing, quality control, and design optimization.
1. Material Selection: The Art of Balancing Performance and Cost
The fundamental requirements are that gears possess high bending fatigue strength, contact fatigue strength, tooth surface hardness, and wear resistance, while maintaining sufficient core toughness to withstand impact loads. For example, alloy carburizing steel (such as 20CrMnTi) can achieve a surface hardness of 58 HRC after carburizing and quenching, offering excellent core toughness and suitability for high-speed, medium-load, and impact applications. Medium-carbon steel (such as 45 steel) offers excellent overall mechanical properties after quenching and tempering, and is relatively cost-effective, making it suitable for light-load applications.
Heat treatment compatibility: The material selection must be compatible with the heat treatment process. For example, case-hardened steel requires carburizing, quenching, and low-temperature tempering to strengthen its surface and increase the tooth surface hardness to 700-900 HV. Quenching and tempering are suitable for medium-carbon steel to achieve a balance between strength and toughness.
2. Processing Technology: A Precise Process from Raw Material to Finished Product
Blank Preparation: Cold or hot forging is used to improve forging accuracy and reduce subsequent machining. Casting is suitable for gears with large diameters or complex structures.
Machining
Gear Hobbing: The tooth profile is cut using the meshing motion of a hob and a gear blank. Accuracy can reach Class 7-8 and is suitable for spur gears and multi-section gears.
Gear Shaping: The tooth profile is formed using an enveloping motion of the gear shaping cutter and the gear blank. It is suitable for internal gears and special gear shapes, achieving accuracy of Class 7-8.
Milling: Gear milling is performed on a milling machine using a gear milling cutter. This process is less expensive but has relatively lower accuracy (Class 11-9). It is suitable for small batches or simple gears. Heat Treatment and Finishing: Heat treatment (such as tempering, surface hardening, and carburizing) strengthens material properties. grinding improves the dimensional accuracy of tooth surfaces, internal bores, and end faces.
3. Quality Control: Strict quality control is implemented throughout the entire process.
Process Monitoring: From raw material forging to finished product processing, key parameters are tested at every step. For example, tooth profile and tooth guide errors are measured after cutting. the hardness and uniformity of the structure after heat treatment are verified.
Finished Product Inspection
Accuracy Inspection: This includes single-angle accuracy (transmission accuracy), operating smoothness (instantaneous transmission ratio changes), load uniformity (contact accuracy), and tooth side clearance.
Performance Testing: Gear transmission efficiency, noise level, and service life are analyzed through experiments or simulations. For example, in high-speed applications, the risk of electrical erosion and galling on the tooth surfaces must be considered. In impact load applications, the bending strength of the tooth root must be verified.
Structural Matching: Ensures compatibility between the gear and other components of the transmission system (such as the motor and bearings) to prevent local defects from affecting overall performance.
4. Design Optimization: An Innovative Path to Performance Improvement
Tooth Profile Parameter Optimization: Reduce transmission friction and impact by adjusting parameters such as module, pressure angle, and addendum height coefficient. For example, increasing the pressure angle improves tooth root strength, but may also increase noise. Using an involute tooth profile can balance transmission efficiency and noise.
System-Level Optimization
Vibration Reduction Design: Introduce shock absorbers or springs to absorb impact forces. optimize gear layout and mounting methods to reduce vibration caused by installation errors.
Lubrication Improvement: Increase lubricant flow and pressure, improve distribution and circulation, and reduce friction and wear.
Intelligent Control: Utilize intelligent algorithms to monitor transmission status in real time and automatically adjust parameters for smooth operation and reduced vibration and impact.
