Due to its accurate accuracy and good surface condition, cold drawn steel products can be directly used, such as spraying, sanding, bending, drilling, or directly electroplated after precision drawing according to actual requirements, eliminating a lot of machining time and saving the cost of configuring processing machinery.

The concept of cold drawing of steel bars: With the aim of saving steel and improving the yield strength of steel bars, the method of stretching steel bars with tensile stress exceeding the yield strength but less than the ultimate strength to produce plastic deformation is called cold drawing of steel bars.

Cold drawing control

1) The situation of cold drawing stress control:

For grade II, III, IV steel bars and grade 5 steel bars, if they are used as prestressed steel bars after cold drawing, cold drawing stress control should be used. However, after inspection of the steel bars after cold drawing, it was found that the large cold drawing rate exceeded the specified value in the specifications, and further mechanical energy experiments are required.

2) Cold drawing rate measurement control requirements:

When controlling the cold drawing rate of steel bars, the control value should be determined by experiments. When conducting experimental measurements, it is required that there should be no less than 4 test specimens from the same furnace and batch. Each specimen should be tested for the corresponding cold drawing rate according to the specified cold drawing stress, and the average value of the specimens should be taken as the actual cold drawing rate of the batch of steel bars in that furnace. If the strength of the steel bars is too high and the average cold drawing rate is less than 1%, the cold drawing rate of 1% should still be controlled during the cold drawing of the steel bars.

3) Cold drawing control for different furnace batches:

For mixed and indistinguishable furnace batches of steel bars, cold drawing rate control cannot be used during cold drawing, and multiple connected steel bars must be cold drawn. The cold drawing rate and control stress of each bar must comply with the specifications.

4) Cold drawing speed control:

To fully deform the steel bars, it is necessary to control the cold drawing speed appropriately, generally ranging from 0.5 to 1.0. At the same time, it is required that after the cold drawing reaches the specified stress and cold drawing rate, the steel bars should be immediately stopped for 2-3 times before relaxing and ending the cold drawing, in order to give the steel bars enough time to deform.

5) Cold drawing control method:

When cold drawing, using only cold drawing rate or cold drawing stress control is called single control. When cold drawing, both cold drawing rate and cold drawing stress are applied simultaneously, which is called dual control. Adopting single control, the construction is simple and convenient. But for steel bars with uneven materials, it is impossible to conduct tests one by one (which is labor-intensive and costly, and it is impossible to do so. Some of the same steel bars have different cold drawing rates), and the quality of cold drawing cannot be guaranteed. The dual control method can avoid the above problems. When cold drawing, if the control stress has been reached and the cold drawing rate does not exceed the allowable value, it can be considered qualified. However, if the cold drawing rate has already been reached and the cold drawing stress cannot reach the control stress, the strength of this type of steel reinforcement needs to be reduced. For prestressed steel bars, a dual control method must be adopted.