Outer circle inner square steel (also known as precision outer circle inner square tube).
Outer circle and inner square steel pipe.
Outer circle inner circle inner square tube structure: it is an economic section steel pipe. Including cross-sectional profile non-circular, equal wall thickness, variable wall thickness, variable diameter and variable wall thickness along the length direction, cross-section symmetrical and asymmetrical, etc. Such as square, rectangle, cone, trapezoidal, spiral, etc. The special-shaped steel pipe can better adapt to the particularity of the use conditions, save metal and improve the labor productivity of parts manufacturing. It is widely used in aviation, automobiles, shipbuilding, mining machinery, agricultural machinery, construction, light textiles and boiler manufacturing. The methods for producing special-shaped pipes include cold drawing, electric welding, extrusion, hot rolling, etc., among which the cold drawing method has been widely used.
An outer circle inner square tube straightening forming method, which comprises the following steps:
Steps. First, according to the cross-sectional size of the forming outer circle inner square pipe, determine the width of the steel coil longitudinal cutting steel strip and the size of the outer circle inner square pipe wall 1-4;
Steps. 2. According to the requirements of the strength grade of the outer circle and the inner square tube, the key process parameters such as the cold-formed forming pass, the forming angle of each pass, and the rebound angle of the steel strip are designed, simulated and optimized by professional analysis software, so as to obtain the optimal forming angle of the cold-formed forming pass and each pass;
Steps. 3. Determine the rolling center line of the steel strip, and feed the steel strip to the frame of the cold-formed forming unit;
Steps. Fourth, install the planing knife holder and blade on the frame of the cold-formed forming unit, and cut the ends on both sides of the steel belt into beveled end faces;
Steps. Fifth, each side corresponding to the rolling center line of steel strip is cold-bent and deformed according to the forming pass and forming angle that is set, until the two ends of the steel strip that are processed into an inclined end face are finally closed on the side parallel to the rolling center, and the two sides ends after closure are welded at high frequency; The two sides of the strip rolling centerline are curved upwards symmetrically at the same angle in the next few passes
The end face of the pipe wall 3 after cold bending is welded with the end face of the pipe wall 4, and the welding burr is removed by adopting the single-arc blade as shown in Figure 5 simultaneously, and the welding surface is guaranteed to be smooth and smooth;
Steps. 6. The double R arc wrapping design is adopted, and the sharp corners at the top and bottom arc angles of the welded outer circle inner square tube are shaped and straightened with the extrusion roller.