How to control the bending accuracy of sheet metal processing within ±0.10mm?
Bending is an essential process in sheet metal processing. Generally, sheet metal parts with a bending accuracy of ±0.10mm are precision sheet metal processing parts. According to the ordinary process of sheet metal processing, laser cutting accuracy can be controlled at about 0.10mm, bending accuracy is controlled at 0.20 ~ 0.30mm is normal, welding accuracy is relatively difficult to control, generally can be controlled at 0.30 ~ 0.50mm is very good. Correspondingly, precision sheet metal processing requires higher dimensional accuracy of parts and aesthetic appearance of surface treatment. The high precision requirement of bending dimensional tolerance of ±0.10mm is its characteristic. If CNC punch is the origin of sheet metal processing, then CNC bending is the origin of precision sheet metal processing. Generally speaking, laser cutting machine and CNC punch to achieve ±0.10mm accuracy is not difficult, but after bending the product size accuracy to reach ±0.10mm, it is not easy to achieve. Then do you know how to control the bending accuracy of sheet metal processing within ±0.10mm?
The bending accuracy of sheet metal processing is controlled within ±0.10mm:
1, bending workers should be skilled, experienced, do not often change the operator. The bending coefficient affects the accuracy of the bending dimension. The bending dimension of sheet metal has been determined when making the expansion drawing. In the expanded diagram, the bending coefficient is the key factor to determine the bending size. The inaccuracy of the calculation of the expansion diagram directly affects the dimensional accuracy of sheet metal bending.
2. Sheet metal technicians are familiar with sheet metal development principle, and can accurately determine the accurate bending coefficient according to theory and practice. The material mass affects the bending dimensional precision, and the thickness of the material directly affects the bending coefficient and the bending precision. Solution: Purchase from large steel mills, strengthen thickness dimension inspection. Different mechanical properties of materials can also affect the bending dimensional accuracy, such as steel plate or soft or hard, resulting in different tensile amount.
3. Try to dry a sheet metal product with the same batch of steel plate, and check the bending coefficient with the same batch of steel plate. To sum up, the bending accuracy of sheet metal processing is controlled within ±0.10mm. In sheet metal processing, CNC bending machine affects the bending accuracy, the stop position of the slider affects the bending Angle, and the position of the rear baffle affects the bending size. These need better CNC bending machine to solve. Therefore, the experience and technique of the operator affect the bending accuracy. Too much or too little force when the worker pushes the baffle will also affect the bending accuracy of sheet metal processing.
Factors affecting bending accuracy：
1. Uneven load of machine tool deflection is the most likely cause of deflection deformation. If the working length of the bending machine is 3200mm, the tonnage of the cylinder distributed on the left and right sides of the machine is 100t. When there is a load, the sliding block will bend and deform, so that the actual displacement of the middle part of the slider is reduced, so that the workpiece in the whole length direction of the Angle is inconsistent, the middle Angle is larger than the two ends of the phenomenon, directly affecting the dimensional accuracy of the workpiece.
2 Calculation accuracy of workpiece developing material The precision of developing material directly affects the size of the workpiece. The size of the workpiece is calculated according to the size of the workpiece. The bending coefficient is used in calculation. This bending coefficient is an empirical data for different materials of different lengths of different shapes of the bending day there are some differences. But the actual calculation uses the same value. There is also a cause of developing material error is the blanking processing error, when the shearing machine blanking will produce a different from the theoretical value of the actual value, which also makes the dimensional accuracy affected.
3, the non-uniformity of the plate of different grades of materials, plate thickness and hardness will have different degrees of deviation, different manufacturers of thickness is also different, material positioning edge if the burr is very large or large contact, forming processing caused by the expansion of the end of the material, the accuracy of bending size will be affected. Or when the plate is rolled, it will bounce back due to uneven strength, resulting in errors in accuracy.
4, springback in the gap bending, due to the change of bending stress plate will produce the maximum bending stress produced in the material bending part of the outer surface. In order to obtain a satisfactory bending Angle, "excess bending" should be implemented。
Reducing the bending deformation of the machine tool itself is a simple way to improve the bending accuracy of the workpiece.
The fundamental starting point is to ensure that the deformation of the sliding block is consistent. Through this consistency, the workpiece is guaranteed to obtain a good consistent Angle in the whole length. The technological measure to achieve this goal is to set up a wedge structure above the upper die to compensate the bending error caused by the upper module of the machine tool.
At the time of operation, the upper slide block is adjusted into a convex arc in the middle before bending processing. After the load is applied, the slide block deformation becomes a straight line to achieve the purpose of basically consistent with the actual displacement. Due to the deformation of the material in each processing of high precision parts should be adjusted on the sliding block preview through the continuous test bending, adjustment, measurement and re-test bending of the cycle way to get the final requirements of dimensional accuracy.
To overcome the precision error due to uneven materials in the selection of materials to choose a uniform texture of the plate, choose professional production of these materials manufacturers. Such manufacturers have perfect production equipment and better technical services. To understand the details of the manufacturer, such as the production license, the main product test report, and then a comprehensive analysis of the manufacturer's various information, whether it can meet the requirements of the enterprise, in order to choose a stable process parameters for processing.The bending process should try to eliminate the impact of the accuracy caused by the material rebound in the actual bending process because the shape of different workpiece processing is not the same, so the need to use different degrees of bending. The material rebound can form a comprehensive effect that affects the dimensional accuracy。
