Common Problems and Treatment in Yuanhao Bending Forming Process

The basic principle of Yuanhao stretch-bending forming is to rotate the bending die around the arm die under the condition that the bending die and the table are fixed, so that the profile wool is plastically deformed under the action of tension and bending moment, and gradually comes into close contact with the die to obtain the required shape Parts. Yuanhao bending is characterized by a large radius of curvature, a large springback, and a change in curvature along the axial direction. Jinan bending is widely used in aviation, aerospace, automobile, real estate and high-speed train industry, bending parts forming. Let's learn about the common problems and treatment in the bending forming process of xiaoyuanhao!

Problems Existing in 1. Yuanhao Bend

1. Profile deviation

The profile degree refers to the degree of conformity between the profile profile after bending and the profile profile after change and the profile template or test tire. The main reasons for the deviation of the profile are: the curvature springback change of the bending die; The material of each batch of metallurgical extrusion profile is unstable, and the hardness of each material is uneven in the local area. The cross-sectional area of the profile blank is uneven due to excessive change of bending radius.

2. Surface defects

Surface defects include cracking, shrinkage, bending surface depression, and side sagging marks after the profile is bent.

3. Bending and torsion

The reason for the distortion after bending is that the cross-sectional area of the profile is asymmetric, and the stress at the end and end of the profile is unbalanced.

4. Perpendicularity out of tolerance

Perpendicularity refers to the angle deviation between the vertical reference of the cross-sectional area of the profile after bending (perpendicular to the radius of curvature of the mold) and the detection platform.

5. Profile processing length

The bending length of the profile refers to the length of the processing material required for bending the mold, fixture, and equipment that exceeds the actual length of the part.

6. Safety in production

Safety is an important issue in industrial production. When the profile is bent, it suddenly breaks due to accidental factors and flies out, which may cause equipment damage and casualties, which seriously affects the development of the enterprise.

Solution to the Problems Existing in 2. Yuanhao Bend

1. Adjust the curvature of the mold contour

On the basis of theoretical analysis, the springback amount is calculated, and the modified approximate value is obtained by the tensile test to correct the mold, so that the profile of the stretched part is as consistent as possible with the profile template or inspection tire. Considering the unstable factors of the profile, it can be pulled slightly according to the needs of later correction. The bending radius of curvature changes greatly, resulting in a certain deviation. Therefore, a cylinder can be added at the front end of the mold, perpendicular to the mold, so that the required curved profile is aligned with the mold. There must be no gap between the bending die and the bent die. This method can solve the bending of different sides of the center of curvature (large radius of curvature). In the design process, the form of the cross-sectional area of the profile and the thickness of each part must be considered. Relative to the asymmetry of the cross-sectional area of the profile, the deviation caused by the imbalance of the tension and the tension stress of the profile can moderately increase the tensile force during the pre-stretching.

2. Surface defect treatment

The profile has cracks after bending because the tensile force is large and does not meet the stress along the edge. Shrinkage wrinkles will occur when the edge of the profile is not reached, commonly known as fungus. This can be solved by improving the cross-sectional area of the profile or adjusting the tensile force. The depression of the curved surface mainly occurs on the cavity profile. This type of material must fill the curved portion of the cavity with filler before bending. The open cavity can be overlapped with spring steel or added with PTFE filler, while the closed cavity is usually filled with sand, etc., and the mold gap is properly adjusted according to the part of the side sagging marks, and the mold material is improved, which can effectively avoid the scratch of the profile.

3. Bending and twisting treatment

The main reason for torsion after bending is the asymmetry of the cross-sectional area and the imbalance of the stress at the end and end of the profile. Therefore, this problem can be improved by increasing the tensile force of the profile. In other words, increase the vertical extrusion cylinder before bending the mold, and after bending, increase the holding pressure for a certain period of time. In addition, slight deformation caused by instability of the extruded profile needs to be carried out in the later correction.

4. Perpendicularity out-of-tolerance treatment

The extremely poor verticality after bending is also caused by the asymmetry of the cross-sectional area and the imbalance of stress at the end and end of the profile. For this case, it can be improved by adjusting the curvature change of the bending mold. According to the needs of the later correction, it can be slightly stretched, but the micro deformation caused by the instability of the extruded profile needs to be carried out in the later correction.

5. Determination of profile processing length

The length of the blanking profile blank is composed of the part length, the mold curvature extension part, the equipment chuck clamping part and the equipment chuck extension mold rotation gap. In addition to the length of the part, collectively referred to as the process length. The length of the mass production process directly determines the cost of the part. Therefore, it is recommended to shorten the effective length of the mold as much as possible under the condition of satisfying the forming of curved parts, and to open cuts at the rear of both ends of the mold as required, so that the chuck of the machine tool in operation can freely enter the rear of the mold and reduce the technical allowance at both ends of the wool.

6. Safety in production

Safety is a noticeable factor in the industrial production process. Therefore, in the production process, protective devices must be added before the profile console, corresponding rules and regulations must be formulated, and comprehensive technical operators must be trained. In addition, during the stretching process of the profile, it is strictly forbidden to stand at the front end of the equipment.