In the production of threaded composite bottom non-stick pans, ensuring a tight and secure connection between the threads and the pan body is crucial for guaranteeing product durability and safety. Achieving this requires a comprehensive approach across seven dimensions: material selection, thread design, processing technology, assembly control, quality inspection, environmental adaptability, and usage and maintenance.
Material selection is fundamental to a strong connection. The pan body is typically made of high-strength stainless steel or aluminum alloy to ensure sufficient tensile strength and toughness. The threads are made of metals compatible with the pan body material, such as copper alloys or special steels, to prevent loosening due to differences in thermal expansion coefficients. The material surface undergoes rigorous cleaning to remove oil, oxide layers, and other impurities, preventing defects during welding or mechanical connections.
The rationality of the thread design directly affects the connection strength. Thread profile, pitch, depth, and other parameters need to be optimized based on the stress characteristics of the pan body and composite bottom. For example, using fine threads increases the contact area and improves shear resistance; a relief groove at the thread termination avoids stress concentration; and a positioning step at the bottom ensures the thread axis is perpendicular to the pan body during assembly, preventing eccentric stress. The precision of the machining process is crucial for ensuring connection quality. Thread machining requires high-precision CNC machine tools to ensure that the thread profile and surface roughness meet design requirements. For welded threads, weld quality must be controlled to avoid defects such as porosity and cracks. For mechanical threads, rolling or cutting processes are necessary to ensure thread integrity, and surface strengthening treatments such as carburizing and quenching may be required to improve wear resistance.
Control during assembly is critical. Threaded connections must follow the "pre-tightening-positioning-tightening" steps: first, preliminary pre-tightening is performed manually or with low-torque tools to ensure proper thread engagement; then, a torque wrench or hydraulic tool is used to apply the final torque according to the design value to avoid insufficient pre-tightening leading to loosening or excessive pre-tightening causing thread damage; for critical parts, double nuts or spring washers can be used to prevent loosening, or anaerobic adhesive can be applied to the thread surface for chemical curing to enhance connection reliability.
Quality inspection is the last line of defense for connection strength. After assembly, multi-dimensional inspection is required: visually inspect the thread surface for scratches and burrs; verify the thread profile dimensions using plug gauges or thread go/no-go gauges; assess the connection strength through tensile testing to ensure it can withstand the design load; perform X-ray or ultrasonic testing on welded threads to check for internal defects; and conduct vibration testing if necessary to simulate dynamic loads during long-term use and verify the anti-loosening effect.
Environmental adaptability optimization can improve the long-term stability of the connection. For different usage scenarios, threaded connections must possess characteristics such as corrosion resistance and high-temperature resistance. For example, in humid environments, the thread surface can be nickel-plated or Dacromet-treated to form a dense oxide film to prevent rust; in high-temperature cooking scenarios, materials with matching coefficients of thermal expansion should be selected to avoid loosening of the connection due to deformation differences during heating; for cookware that is frequently disassembled, the threads must have sufficient wear resistance to prevent a decrease in fit precision after repeated assembly and disassembly.
Usage and maintenance guidelines can extend the connection life. The user manual should clearly specify the usage guidelines for the threaded composite bottom non-stick pan, such as avoiding dry heating to prevent localized overheating and thus preventing thread deformation due to thermal stress; prohibiting the use of steel wool or other hard objects to scrape the threaded area during cleaning to avoid damaging the tooth profile; and separating the pan body from the composite bottom for long-term storage to prevent creep of the threads due to prolonged pressure. Proper use will maximize the tightness of the threaded connection.
