Simple and Efficient Cookware Processing Solution
In the stainless steel cookware manufacturing industry, edge annealing is a crucial pre-processing step before stretching, directly affecting subsequent processing accuracy and product quality. This simplified automated equipment achieves seamless integration of stainless steel cookware edge annealing and stretching through an integrated design of conveyor belt transport, high-frequency annealing, and clamp linkage, solving the problems of low efficiency and uneven annealing associated with traditional manual operations. The following is a detailed analysis of the equipment architecture, process flow, and application advantages:
I. Core Equipment Architecture and Process Flow—Full-Process Automation Design
- Feeding and conveying module: Stainless steel pot blanks are manually placed on the conveyor belt (speed 0.5-1m/min), and positioning accuracy is ensured by limit baffles (deviation ≤±1mm); the conveyor belt is made of high temperature resistant silicone to avoid scratching the surface of the pot, and is compatible with round pot blanks with a diameter of 180-300mm.
- Automated fixture positioning: When the pot blank reaches the designated position, the pneumatic fixture (positioning accuracy ±0.05mm) automatically clamps the pot edge, and at the same time the lifting mechanism lifts the pot blank vertically, exposing the area to be annealed (pot edge width 10-20mm).
- High-frequency annealing module: A custom-designed ring induction coil (with an inner diameter 20mm larger than the pot blank) descends to a distance of 5-8mm from the edge of the pot, and a 200kHz high-frequency current is applied. Within 3-5 seconds, the temperature of the pot edge is raised to 750-800℃ (the annealing temperature range for stainless steel). An infrared thermometer monitors the temperature in real time. Once the set value is reached, the coil automatically rises. The annealing time error is ≤±0.5 seconds.
- Secondary loading and unloading: After the clamps are released, the pot blank falls back to the conveyor belt and is pushed to the stretching station by subsequent clamps; unqualified products (such as insufficient annealing temperature) are detected by photoelectric sensors and pushed into the waste trough by sorting cylinders, with an automation rate of over 95%.
II. Technological Advantages: Dual Guarantee of Precise Annealing and High-Efficiency Production
1. Annealing quality is significantly improved.
- Temperature uniformity: The circumferential temperature deviation around the pot edge is ≤ ±5℃, which is a significant improvement over traditional flame annealing (deviation ±15℃), avoiding grain coarsening or overheating defects caused by local overheating.
- Microstructure optimization: After annealing, the grain size of stainless steel is controlled at 20-30μm (standard requirement ≤40μm), the hardness is reduced from HV200-250 before annealing to HV140-160, and the elongation is increased to more than 40%, which significantly improves the subsequent tensile forming performance.
2. Production efficiency leap
- Unmanned operation: Only one worker is needed to be responsible for material loading and equipment monitoring, which reduces the number of operators by 3-4 compared to traditional processes, and reduces labor costs by 60%.
- Seamless process connection: The distance between the annealing and stretching stations is ≤1 meter, and the blank does not need to be handled twice, shortening the process cycle by 40%. With the subsequent automated stretching machine, the entire process of "annealing - stretching - flanging" can be completed in 30 seconds per piece.
3. Equipment simplicity and flexibility
- Low-cost investment: The total investment in equipment is about 200,000 to 300,000 yuan, which is only 1/3 of that of a fully servo-automated line, making it suitable for the upgrade needs of small and medium-sized cookware factories.
- Quick changeover capability: By changing the fixture module (changeover time ≤ 10 minutes), it can be compatible with pot blanks of different diameters, supporting small-batch production of multiple varieties.
III. Typical Application Scenarios and Effect Data
1. Annealing a household stainless steel wok
- Workpiece: 280mm diameter wok (material: 304 stainless steel, thickness: 1.2mm)
- Frequency 200kHz, power 18kW, annealing time 4 seconds;
- The induction coil is 15mm wide and covers the annealing area around the edge of the pot.
- After stretch forming, the crack rate at the edge of the pot decreased from 8% in the traditional process to 1.5%;
- With a surface roughness Ra≤1.6μm, no further polishing is required, and the yield rate is improved to 98%.
2. Annealing of commercial stainless steel soup pots
- Workpiece: 300mm diameter soup pot (material: 430 stainless steel, thickness: 2.0mm);
- Processing challenges: Annealing thick-walled pot edges requires ensuring deep tissue softening;
- Solution: Use a "dual-frequency annealing" process: first preheat to 500℃ at 50kHz (heating depth 2mm), then rapidly heat to 800℃ at 200kHz; cooling method: air cooling to room temperature to avoid residual stress caused by rapid cooling;
- Results: The uniformity of hardness after annealing is ≤5HV, and the maximum thinning rate during stretching reaches 35%, meeting the high strength requirements of commercial cookware.
IV. Key Points of Equipment Maintenance and Operation
- Fixture calibration: Check the positioning accuracy of the fixture weekly with a dial indicator, and replace it promptly when wear exceeds 0.1mm;
- Coil cleaning: Blow away metal debris from the surface of the induction coil daily with compressed air to avoid the risk of short circuit;
- Infrared temperature measurement calibration: The temperature measurement module is calibrated monthly using a standard blackbody furnace to ensure that the temperature detection error is ≤ ±2℃.
2. Safe Operating Procedures
- Maintain a safe distance of ≥1 meter when the equipment is running to avoid high-frequency radiation;
- Disconnect the power supply when changing clamps or coils to prevent accidental start-up;
- Equipped with dry powder fire extinguishers to deal with the potential risk of short circuit fires.
V. Investment Returns and Upgrade Recommendations
1. Cost-benefit analysis
Based on an annual production capacity of 300,000 units: Equipment investment: US$30,000; Annual labor cost savings: US$20,000 (reducing the number of workers by 3); Annual material loss savings: approximately 2 tons of stainless steel sheet due to reduced crack rate; Investment payback period: approximately 14 months.
2. Intelligent Upgrade Path
Add visual inspection: Add an industrial camera after the annealing station to detect the color of the pot edge in real time (to judge temperature uniformity), and automatically reject defective products; Connect to MES system: Record data such as annealing time, temperature, and fixture number of each pot blank to achieve full quality traceability; Servo motor upgrade: Replace the pneumatic fixture with a servo electric fixture, improve the positioning accuracy to ±0.02mm, and adapt to higher precision pot production.
This simple automated stainless steel pot rim annealing and stretching equipment offers small and medium-sized cookware manufacturers an efficient path to automation upgrades, characterized by "low cost, high adaptability, and easy maintenance." Its precise temperature control and smooth process integration not only solve the quality pain points of traditional annealing processes but also help companies enhance their market competitiveness through large-scale production capabilities. Whether for mass production of household cookware or customized processing of commercial kitchenware, this equipment consistently delivers stable performance, becoming a core asset on the production line.
No. 15, Yanqiao Road, Yanqiao Street, Huishan District, Wuxi City, Jiangsu Province, China