GB/T 33878-2017Steel cross wedge rollings - Technological design principle (English PDF)

4.1 Technological Design

4.1.1 The manufacturing procedure of steel cross wedge rollings mainly includes: cutting - heating - rolling - hot alignment - thermal treatment - surface cleaning - cold straightening - sawing of finished product - inspection. The arrangement of the procedure shall consider the convenience of material flow throughout the whole manufacturing process; the control of manufacturing cost, the quality requirements from clients and the condition of equipment, etc.

4.1.2 Casual inspection shall be conducted in each procedure in accordance with product's characteristics.

8 In accordance with product requirements, select corresponding thermal treatment equipment.

4.3.6 Surface cleaning Suitable surface cleaning equipment can be selected in accordance with product dimension, texture, shape, surface quality and processing precision requirement, etc.

4.3.7 Cold straightening Select suitable equipment to conduct cold straightening on rolled parts with extremely low straightness accuracy. In addition, eliminate residual stress in accordance with clients' requirements.

4.3.8 Sawing of finished product Toothless saw and band sawing machine can be adopted. When toothless saw is used, prevent over-burned tissue around the sawed area.

4.4 Mold Design

4.4.1 In the selection of mold parameters, including the forming angle () and widening angle (beta), several factors shall be comprehensively considered, such as the percentage reduction of area (psi) of rolled parts, length of roll face and avoidance of product defects, etc. The forming angle shall be selected within the range of 18° ~ 34°; the widening angle shall be selected within the range of 4° ~ 12°.

4.4.2 Try to make sure cavities on both sides of the mold are the same. In terms of relatively short axial asymmetrical workpieces, combine 2 or more workpieces to make them symmetrical, then, start rolling.

4.4.3 Place the side that is not involved in rolling, or the side that manifests slight deformation, on the end of the rolled parts, so that the loss of head materials can be reduced.

4.4.4 When the percentage reduction of area is greater than 80%, the design method of secondary wedge or reduced forming angle can be adopted.

4.4.5 In terms of parts that will easily lead to defects like loosening and hollowness, increase the forming angle.

4.4.6 In order to decrease spiral mark, a transition fillet R can be designed between the forming surface and the top surface.

4.4.7 In order to guarantee the rotation of rolled parts, anti-slip mark can be added on the bevel of the forming angle.

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