How is the sheet drawing process for tea residue filter tube?
Publish Time: 2025-03-24
The sheet drawing process for tea residue filter tube is a key manufacturing link to transform flat stainless steel sheets into three-dimensional filtering structures. This precision forming process directly determines the mechanical strength, filtration accuracy and service life of the filter tube, and requires comprehensive consideration of multiple factors such as material properties, mold design and process parameters.In the initial stage of the drawing process, the selection of raw materials is crucial. Commonly used 304 and 201 stainless steel sheets need to undergo strict factory inspection to ensure that the thickness tolerance is controlled within ±0.02mm and there are no scratches and oxidation defects on the surface. For food contact products such as tea residue filter tube, the material must also comply with the GB 4806.9 food safety standard. The pretreatment process includes precise cutting and surface cleaning of the sheet to remove oil and impurities to create ideal conditions for subsequent drawing.Mold design is the core technology of the drawing process. The drawing mold for tea residue filter tube usually adopts a split structure, consisting of a punch, a die and a pressure ring. The surface roughness of the working surface of the mold is required to be below Ra0.4 to ensure smooth material flow during the drawing process. The die gap is set to 1.1-1.2 times the material thickness. This precise space allows metal to flow without excessive thinning. In view of the unique microporous structure of the filter tube, the die is also designed with precise guide grooves to guide the metal to flow in a specific direction to form a uniform wall thickness distribution.The process parameters during the stretching process are controlled very finely. The deformation of the first stretching is usually controlled between 30%-40% to avoid excessive deformation at one time and cause rupture. During multiple stretching, annealing processes need to be arranged in the middle to eliminate work hardening. The speed of the press is controlled within the range of 5-10mm/s. Too fast will cause local stress concentration, and too slow will affect production efficiency. The setting of the blanking force is particularly critical, generally between 2-3MPa, which should prevent wrinkling and not hinder material flow. Advanced CNC stretching equipment can monitor these parameters in real time and automatically adjust them through a closed-loop control system to ensure process stability.The unique microporous structure of tea residue filter tube brings special challenges to the stretching process. On the basis of traditional stretching, it is necessary to combine the hole expansion process to form the filter hole simultaneously. This requires precise control of the material flow direction during the stretching process, so that the metal gathers in the non-porous area and retains sufficient strength for subsequent punching. The latest process uses laser-assisted stretching technology to pre-process laser micro-processing at specific locations, change the local properties of the material, and guide the metal to flow along the designed path. This innovative method makes the distribution of filter holes more uniform, and the filtration accuracy can be controlled within the range of 50-100μm.The heat treatment after stretching has a significant impact on the final performance of the product. Solution treatment can eliminate processing stress and restore the corrosion resistance of the material. For 201 stainless steel, the treatment temperature is controlled at 1010-1050℃; for 304 stainless steel, it is 1040-1100℃. The rapid cooling process requires precise control to ensure a uniform austenite structure. The heat-treated products are also passivated to form a dense chromium oxide protective film on the surface to improve corrosion resistance.The quality inspection link ensures that each product meets the standards. The wall thickness is measured by an ultrasonic thickness gauge with an accuracy of up to 0.01mm; the micropore size is detected by an optical projector; the sealing test uses a 0.3MPa air pressure test. Only products that pass these rigorous tests can enter the polishing process and eventually become qualified tea residue filter tubes.With the development of intelligent manufacturing technology, the stretching process of tea residue filter tubes is evolving towards digitalization. The process parameter optimization system based on artificial intelligence can autonomously learn the best production plan, and the digital twin technology allows the feasibility of the process to be verified in a virtual environment. These innovations continue to promote the advancement of tea residue filter tube manufacturing technology.
