How to bend bamboo pieces

Calculation method of k coefficient value deducted from bending coefficient 1 The calculation method of sheet metal parts is introduced. Engineers of sheet metal parts and sellers of sheet metal materials will use various algorithms to calculate the actual length of materials in the unfolded state to ensure the expected size of the parts after final bending. One of the most commonly used methods is a simple "pinch rule", that is, an algorithm based on one's own experience. Generally, these rules should consider the type and thickness of materials, the radius and angle of bending, the type and stepping speed of machine tools and so on. On the other hand, with the emergence and popularization of computer technology, in order to make better use of the superior analysis and calculation ability of computers, people are increasingly adopting computer-aided design. However, when computer programs simulate the bending or unfolding of sheet metal, a calculation method is also needed to accurately simulate this process. Although each store can customize a specific program implementation according to its original finger-pinching rules, it is only used to complete a certain calculation, and most commercial CAD and 3D solid modeling systems have provided more general and powerful solutions. In most cases, these applications can also be compatible with the original methods based on experience and pinching rules, and provide methods to customize specific inputs into their calculation process. SolidWorks has naturally become a leader in providing this kind of sheet metal design capability. To sum up, there are two popular algorithms for sheet metal bending, one is based on bending compensation, and the other is based on bending deduction. SolidWorks software only supported the bending compensation algorithm before the 2003 edition, but since the 2003 edition, both algorithms have been supported. In order to make readers better understand some basic concepts in the process of sheet metal design and calculation, and also to introduce the specific implementation method in SolidWorks, this paper will summarize and expound the following aspects: 1, the definitions of bending compensation and bending deduction, and their respective corresponding relationships with the actual sheet metal geometry. 2. How does bending deduction correspond to bending compensation? How can users who use the bending deduction algorithm easily convert their data into the bending compensation algorithm? 3. How to use the K-factor in practice, including the scope of application of K-factor values for different material types? 2. Bending compensation method For a better understanding of bending compensation, please refer to Figure 1, which shows a single bending in a sheet metal part. Fig. 2 is the unfolded state of this part. The bending compensation algorithm in figure 1 describes the unfolded length (LT) of the part as the sum of the length of each section after flattening of the part and the length of the flattened bending area. The length of the flattened bending area is expressed as the bending compensation value (BA). Therefore, the length of the whole part is expressed by the equation (1): lt = d1+D2+ba (1). The bending area in Figure 2 (light yellow area in the figure) is a theoretically deformed area in the bending process. In short, in order to determine the geometric size of the unfolded part, let's think according to the following steps: 1, cutting the curved area from the curved part, 2, tiling the remaining two flat parts on the table, 3, calculating the length of the flattened curved area, and 4, gluing the flattened curved area between the two flat parts. Therefore, the slightly difficult part of the unfolding part we need is how to determine the length of the flattened bending area, which is represented by BA in the figure. Obviously, the value of BA will vary with the material type, material thickness, bending radius and angle. Other factors that may affect BA value include processing technology, machine tool type, machine tool speed, etc. Where does the BA value come from? In fact, there are usually the following sources: sheet metal material suppliers, experimental data, experience and some engineering manuals. In SolidWorks, we can directly input the BA value and provide one or more tables with BA value, or we can use other methods such as K factor (discussed in depth later) to calculate the BA value. For all these methods, we can input the same information for all bends in the part, or we can input different information for each bend as needed. For various cases with different thickness, bending radius and bending angle, the bending table method is the most accurate method for us to specify different bending compensation values. Generally speaking, there will be a table for each material or each material/processing combination. It may take some time to form the initial table, but once the initial table is formed, we can reuse some parts of it in the future. Third, the bending deduction method Bending deduction usually refers to the amount of tool withdrawal, which is also a different simple algorithm to describe the bending process of sheet metal. Still referring to Figure 1 and Figure 2, the bending deduction method means that the flattened length LT of the part is equal to the sum of the theoretical lengths of two flat parts extending to the "cusp" (the virtual intersection of two flat parts) minus the bending deduction (BD). Therefore, the total length of parts can be expressed as equation (2):lt = l 1+L2-BD(2) Bending deduction is also determined or provided through the following channels: sheet metal material suppliers, test data, experience, manuals with equations or tables of different materials, etc. Fourthly, the relationship between bending compensation and bending deduction is known to users who are familiar with bending deduction method, because SolidWorks usually adopts bending compensation method. In fact, it is easy to get two values by using the bending and unfolding geometry of the part.