Grain-Oriented Silicon Steel Lamination

Grain-Oriented Silicon Steel Lamination is the key material for manufacturing high-performance transformer cores, and stacking these thin silicon steel sheets into a core is the core process that determines transformer performance. The following description covers three aspects: material, structure, and process.

Raw Material of Oriented Core: Grain-Oriented Silicon Steel

The reason of a transformer core is called an "oriented core" lies in the use of grain-oriented silicon steel, a special material.

•  Unique Grain Orientation: This silicon steel undergoes special processing during production, which aligns the internal grains in a consistent magnetic orientation along the rolling direction. Simply put, in this direction, the material exhibits the best magnetic permeability and the lowest losses.

• Application Principle: Therefore, when designing the core, the main path of the magnetic flux must pass along the rolling direction of the oriented silicon steel to fully leverage its advantages of low loss and high permeability. All high-performance transformer cores follow this design principle.

Structure of Laminated Core: From Individual Sheets to an Integrated Whole

After cutting oriented silicon steel into specific shapes, stacking them piece by piece forms the main body of the core.

• Basic Forms: Common core structures include the "日" shape (for single-phase transformers), "E" shape, and "日" shape. They all consist of core limbs (where the coils are wound) and yokes (which connect the limbs to form the magnetic circuit).

• Detail Design for Loss Reduction:

1. Joint Treatment: To reduce magnetic resistance and losses at the joints, the joints of silicon steel sheets in adjacent layers are staggered and overlapped, rather than aligned in a straight line.

2.  Cross-sectional Shape: To maximize the effective cross-sectional area within a limited space, the cross-section of core limbs is often designed as a stepped or cruciform shape, stacked with silicon steel sheets of varying widths.

Lamination Process: From Manual to Automatic

The process of stacking grain-oriented silicon steel sheets into a core is called "lamination."

• Manual/Semi-automatic Lamination: The traditional process relies on manual labor to place the silicon steel sheets layer by layer according to drawings, which is inefficient, requires high skill, and makes quality stability difficult to guarantee. Some improved processes can assist a single worker in completing part of the stacking work.

•  Fully Automatic Lamination Production Line: This is the mainstream method in modern large-scale transformer manufacturing. Its core process typically includes:

  1. Automatic Sheet Separation and Feeding: Devices separate the silicon steel sheets one by one and position them precisely.

  2. Robotic Gripping and Pre-positioning: A robotic arm grips the sheets and places them on a pre-positioning table, automatically adjusting their position and even detecting whether the sheet type is correct.

  3. Precise Stacking: The robotic arm places the sheets precisely onto the stacking table according to programmed instructions. During this process, a height-measuring device automatically compensates for height to ensure consistent stacking thickness.

  4. Integrated Forming: After all sheets are stacked, the core is moved out together with the stacking table for subsequent processes such as clamping and flipping.

In short, the grain-oriented core is the result, and laminated core refers to the process. By using the special material of grain-oriented silicon steel and through precise lamination processes (from manual to automated), a high-performance oriented laminated core is produced.