1.What are the working principles and applicable scenarios of two-roller oiling?
Working Principle: It consists of an "oil supply roller" (which contacts an oil tank/oil pipe and absorbs oil) and an "oiling roller" (which directly contacts the strip surface). The oil supply roller transfers oil to the oiling roller, which then coordinates the pressure and speed of the oiling roller with the strip to evenly coat the oil on the upper and lower surfaces (the amount of oil applied to the upper and lower surfaces can be controlled separately).
Key Controls: By adjusting the "oiling roller pressure" (the higher the pressure, the thinner the oil film), the "roller speed" (matching the strip speed to avoid uneven oil film), and the "oil tank level" (ensuring stable oil supply), precise control of the oil film thickness (from light to medium oiling) is achieved within a range of 5-20mg/㎡.
Applications: General-purpose galvanized coils (such as those used in home appliances and building materials), especially suitable for subsequent painting and lamination (the oil film is thin and uniform, easy to clean, and compatible with subsequent processes). Advantages and Disadvantages: Advantages include uniform oil film, controllable oiling amount, and adaptability to high-speed production lines (strip speeds can reach over 1000m/min). Disadvantages include high equipment costs and the need for regular maintenance of the oiling rollers (to prevent oil film defects caused by roller surface wear).
2.What are the working principles and applicable scenarios of three-roller oiling?
Working Principle: Based on the "oil supply roller + oiling roller," a "scraper roller" (located outside the oiling roller) is added. The gap between the scraper roller and the oiling roller is adjusted to further control the oil film thickness. The scraper roller scrapes away excess oil from the oiling roller surface, achieving a thicker or more uniform oil film (e.g., a heavy oiling of 20-50mg/㎡).
Application Scenarios: For galvanized coils requiring long-term storage (e.g., overseas export, inventory exceeding three months), or high processing requirements (e.g., deep-drawn automotive parts), a thicker oil film provides enhanced rust prevention and lubricity.
Advantages and Disadvantages: Advantages include a wider oil film thickness range and higher accuracy. Disadvantages include a more complex structure and the need for precise calibration of the scraper roller, otherwise a "streak-like oil film" defect can occur.
3.What is the working principle and applicable scenarios of the spray method (local/quick oiling)?
Working Principle: Oil (usually atomized oil) is evenly sprayed onto the strip surface through a high-pressure nozzle. Some production lines utilize a scraper or suction roller to control the oil film thickness and prevent excessive oil accumulation.
Applicable Applications:
Repairing small batches of galvanized coils (e.g., repairing oil film leaks during production);
Local oiling of strip edges (in some cases, only the edges need rust protection, reducing oil consumption);
Quickly forming a simple oil film for temporarily stored semi-finished products.
4.What are the working principles and applicable scenarios of dip coating?
Working Principle: Galvanized coils (usually small coils or single sheets) are directly immersed in an oil bath. By controlling the immersion time (usually 10-30 seconds) and the oil temperature (some oils require heating to improve fluidity), the oil adheres to the zinc surface. After removal, excess oil is drained, forming a thick oil film (over 50-100 mg/㎡).
Applications:
Galvanized coils stored outdoors for long periods or transported in harsh environments (such as engineering steel shipped by sea) require a thick oil film to withstand high humidity and salt spray.
Semi-finished products without further processing (such as temporarily stored raw material coils) do not require oil film cleaning.
5.What are the key considerations when choosing an oiling method?
Production Speed: For continuous high-speed production lines (such as hot-dip galvanizing lines), two-roller/three-roller coating is preferred; for small-batch, intermittent production, spraying/dip coating is recommended.
Oil Film Precision: For subsequent painting and lamination (requiring a thin and uniform oil film), choose two-roller coating; for long-term storage (requiring a thick oil film), choose three-roller/dip coating.
Cost Control: For large-scale production, roller coating is preferred (due to its high long-term efficiency and manageable oil consumption); spraying is recommended for temporary touch-ups or small-scale products (due to its low equipment cost).
Environmental Requirements: Some regions have requirements for oil volatility; low-VOC oils should be selected, and an oil mist recovery device (required for both roller and spray coating) should be used to reduce environmental pollution.