Product Design Of Screws And Nuts

The product design of screws and nuts encompasses various aspects - such as structural elements, performance standards, application specifications, and anti-loosening technologies - aimed at meeting requirements for fastening, sealing, vibration resistance, and lightweighting under diverse operating conditions. Design precision is particularly critical in high-end manufacturing sectors such as automotive, wind power, and aerospace.

Design of Structural Elements

The design of structural elements for automotive fastener connections must strictly adhere to international (ISO) and national (GB) standards. Key considerations include thread end types (e.g., flat, chamfered/scraped, or truncated cone pilot ends), thread run-out, shoulder distance, and thread relief grooves, all intended to prevent "false torque" readings. Thread engagement depth for bolts and screws must be verified based on the material being joined (steel, bronze, cast iron, or aluminum) using multiples of the nominal diameter (e.g., 1d, 1.5d, or 2d).

Torque Standards

Torque standards for automotive screws include general benchmarks (e.g., specific torque values ​​for metric coarse thread sizes like M3, M5, M8, and M12 across various performance classes) as well as specialized specifications for critical components like engines. Calibrated torque wrenches must be used during assembly, with errors controlled within a ±10% range; torque values ​​must also be adjusted according to the specific materials involved (e.g., aluminum alloy versus cast iron).

Application Example: Automotive Seat Screws

Automotive seat screws come in a variety of models, with common specifications including M6, M8, and M10. Types include flat-head, threaded, triangular-thread, and self-tapping screws, with specific models varying by vehicle type.

Principles and Technologies of Modern Anti-Loosening Design

Modern anti-loosening technology has evolved beyond traditional thread structures, giving rise to numerous innovative designs. Examples include anti-loosening threads that utilize asymmetric profiles to generate controlled plastic deformation; bolts treated with high-hardness, low-friction surface coatings; assembly techniques that ensure tightening quality through real-time torque-angle monitoring; and methods that reduce the number of connection points through integrated die-casting or "module-free" designs. Furthermore, patented innovations within the industry reflect the ongoing advancement of anti-loosening technologies.