Translation:
The bending coefficient refers to the elongation of the sheet metal after bending. It varies depending on the material, thickness of the sheet, and the type of bending die used. Here are some explanations regarding the coefficient:
1. The algorithm for calculating the bending coefficient is usually based on a 90-degree bend, and the specific data depends on the grooves of the bending machine and the sheet metal material being used.
2. The bending coefficient includes two definitions (bending deduction ΔK and bending coefficient ΔT), which represent two different algorithms. However, regardless of which algorithm is used, the final unfolded value remains the same.
3. The specific algorithms are as follows: the bending deduction ΔK is the sum of the outer dimensions minus the unfolded length L, while the bending coefficient ΔT is the unfolded length L minus the sum of the inner dimensions.
For example, if the bending shape is L-shaped, with outer dimensions A and B, inner dimensions a and b, unfolded length L, and material thickness T:
ΔK = A + B - L; ΔT = L - (a + b); it follows that ΔK = 2T - ΔT.
The bending coefficient is related to the material, bending radius/sheet thickness, V-groove width, and the radius of the upper die.
For lengths below 4m, it is considered as the inner layer; for lengths between 4m and 10m, it is considered as the middle layer. Beyond that, it should be considered as the upper-middle layer, which requires a coefficient.
There are two methods:
1. Determine the coefficient for the middle layer of this material based on actual results and calculated values.
2. Calculate the theoretical value based on the cross-sectional density and make adjustments accordingly.
The Importance of Determining the Bending Coefficient
In sheet metal fabrication, when calculating the flat pattern of a part, technicians rely on their experience to determine the bending coefficient (i.e., consumption). Different technicians may come up with different bending coefficients in their process documents. By referring to various sheet metal processing manuals, no specific formula for calculating the bending coefficient has been found. Only bending coefficients for different internal circular arcs can be found, and the bending coefficient for internal circular arcs depends on the specific processing methods and the width of the lower die groove. This makes it difficult to determine the correct bending coefficient value in process documents. This not only affects the standardization and rationalization of process documents but also brings difficulties to production in the workshop and leads to unstable product quality.
With the continuous advancement of science and technology, computer applications are gradually developing towards the CIM (Computer Integrated Manufacturing) system. In order to discuss computer-aided process development, including the automatic generation of process documents, automatic calculation of flat patterns, and automatic calculation of material consumption quotas, it is necessary to first solve the automatic determination of the bending coefficient, which is the automatic calculation of flat patterns.
Some manufacturers in the Beijing area are implementing CIM systems, but their software has not solved this problem. As for the manufacturers of CNC machine tools, the determination of the bending coefficient is a patented product and is kept confidential from the users of the machine tools. Therefore, it is necessary to independently solve the calculation method for determining the bending coefficient.
2. Theoretical Calculation of Flat Patterns
During sheet metal bending, compression occurs on the inner side while stretching occurs on the outer side. The compression on the inner side gradually decreases from the outside, and the stretching on the outer side gradually decreases from the inside. Near the center of the sheet, compression and stretching approach zero. This middle layer, where the compression and stretching are balanced, is called the neutral layer. The theoretical calculation of flat patterns is based on this neutral layer.
2.1 Bending with an Inner Arc Radius R ≥ 5t (t is the material thickness)
When the inner arc radius of the bend is greater than or equal to 5 times the material thickness, there is no thickness change in the material at the bend, and the neutral layer is located on the centerline of the material thickness.
Let b be the distance from the neutral layer to the inner wall of the sheet, a be the bending angle, T be the sheet thickness, and K be a bending factor. K = b/T, and K represents the bending coefficient of the neutral layer. During bending, the material undergoes deformation, with the outer layer being stretched and the inner layer being compressed, while the length of the neutral layer remains unchanged. Materials with higher hardness have less stretching deformation, so the neutral layer is closer to the outer side, while materials with lower hardness have greater stretching deformation, so the neutral layer is closer to the inner side. For ordinary materials, the neutral layer tends to be in the middle. In the diagram, copper and soft steel are on the left, ordinary steel plate is in the middle, and hard steel and stainless steel are on the right. The unfolded length of the material is the arc length of the neutral layer. It depends on several parameters: the bending radius, bending angle, sheet thickness, and the coefficient of the neutral layer.
The unfolded length is calculated as: DL = Pi * (R + K * T) * a / 180.
PROE also uses a Y factor to calculate the unfolded length, where Y = Pi/2 * K.
The formula becomes: DL = (Pi/2 * R + Y * T) * a / 90.
If there is no specific bending table, PROE uses this formula to calculate the unfolded length. Therefore, when starting a sheet metal fabrication, it is necessary to define the value of K or Y. The default Y value in the system is 0.5, which corresponds to soft steel and copper. If using ordinary steel plate, the K value can be set to 0.45, which is equivalent to a Y value of 0.707. "The unfolded dimensions are calculated based on the neutral layer, and the unfolded length is related to the bending die radius. Check the dimensions of the actual part after bending to identify any regular patterns, and then modify the unfolded cutting dimensions accordingly based on this experience." The neutral layer is accurate, but different practices or different groove widths of the bending die result in different bending radii, making it impossible to calculate the neutral layer. Generally, different sheet thicknesses are tested with the same groove width, and different groove widths are tested with the same sheet thickness to obtain empirical data. However, different batches of materials often have differences. Researching this problem with such an attitude will never lead to a real answer. Think about what they are answering. How can people understand if both the methods and the problems are not resolved? This is very irresponsible in terms of communication.
As technology advances, computer applications are gradually evolving towards CIM (Computer Integrated Manufacturing) systems. To discuss computer-aided process development, including the automatic generation of process documents, automatic calculation of flat patterns, and automatic calculation of material consumption quotas, it is necessary to first solve the automatic determination of the bending coefficient, which is the automatic calculation of flat patterns.
Some manufacturers in the Beijing area who are implementing CIM systems have not solved this problem with their software. As for the manufacturers of CNC machine tools, the determination of the bending coefficient is a patented product and kept confidential from the users of the machine tools. Therefore, it is necessary to independently solve the calculation method for determining the bending coefficient.
2. Theoretical Calculation of Flat Patterns
During sheet metal bending, compression occurs on the inner side while stretching occurs on the outer side. The compression on the inner side gradually decreases from the outside, and the stretching on the outer side gradually decreases from the inside. Near the center of the sheet, compression and stretching approach zero. This middle layer, where the compression and stretching are balanced, is called the neutral layer. The following calculations are based on the neutral layer.
2.1 Bending with an Inner Arc Radius R ≥ 5t (t is the material thickness)
When the inner arc radius of the bend is greater than or equal to 5 times the material thickness, there is no thickness change in the material at the bend, and the neutral layer is located on the centerline of the material thickness.
Let b be the distance from the neutral layer to the inner wall of the sheet, a be the bending angle, T be the sheet thickness, and K be a bending factor. K = b/T, and K represents the bending coefficient of the neutral layer. During bending, the material undergoes deformation, with the outer layer being stretched and the inner layer being compressed, while the length of the neutral layer remains unchanged. Materials with higher hardness have less stretching deformation, so the neutral layer is closer to the outer side, while materials with lower hardness have greater stretching deformation, so the neutral layer is closer to the inner side. For ordinary materials, the neutral layer tends to be in the middle. In the diagram, copper and soft steel are on the left, ordinary steel plate is in the middle, and hard steel and stainless steel are on the right. The unfolded length of the material is the arc length of the neutral layer. It depends on several parameters: the bending radius, bending angle, sheet thickness, and the coefficient of the neutral layer.
As shown in the diagram, the unfolded length is calculated as: DL = Pi * (R + K * T) * a / 180.
PROE also uses a Y factor to calculate the unfolded length, where Y = Pi/2 * K.
The formula becomes: DL = (Pi/2 * R + Y * T) * a / 90.
If there is no specific bending table, PROE uses this formula to calculate the unfolded length. Therefore, when starting a sheet metal fabrication, it is necessary to define the value of K or Y. The default Y value in the system is 0.5, which corresponds to soft steel and copper. If using ordinary steel plate, the K value can be set to 0.45, which is equivalent to a Y value of 0.707.
The bending coefficient refers to the elongation of the sheet metal after bending. It varies depending on the material, thickness of the sheet, and the type of bending die used. Here are some explanations regarding the coefficient:
1. The algorithm for calculating the bending coefficient is usually based on a 90-degree bend, and the specific data depends on the grooves of the bending machine and the sheet metal material being used.
2. The bending coefficient includes two definitions (bending deduction ΔK and bending coefficient ΔT), which represent two different algorithms. However, regardless of which algorithm is used, the final unfolded value remains the same.
3. The specific algorithms are as follows: the bending deduction ΔK is the sum of the outer dimensions minus the unfolded length L, while the bending coefficient ΔT is the unfolded length L minus the sum of the inner dimensions.
For example, if the bending shape is L-shaped, with outer dimensions A and B, inner dimensions a and b, unfolded length L, and material thickness T:
ΔK = A + B - L; ΔT = L - (a + b); it follows that ΔK = 2T - ΔT.
The bending coefficient is related to the material, bending radius/sheet thickness, V-groove width, and the radius of the upper die.
For lengths below 4m, it is considered as the inner layer; for lengths between 4m and 10m, it is considered as the middle layer. Beyond that, it should be considered as the upper-middle layer, which requires a coefficient.
There are two methods:
1. Determine the coefficient for the middle layer of this material based on actual results and calculated values.
2. Calculate the theoretical value based on the cross-sectional density and make adjustments accordingly.
The Importance of Determining the Bending Coefficient
In sheet metal fabrication, when calculating the flat pattern of a part, technicians rely on their experience to determine the bending coefficient (i.e., consumption). Different technicians may come up with different bending coefficients in their process documents. By referring to various sheet metal processing manuals, no specific formula for calculating the bending coefficient has been found. Only bending coefficients for different internal circular arcs can be found, and the bending coefficient for internal circular arcs depends on the specific processing methods and the width of the lower die groove. This makes it difficult to determine the correct bending coefficient value in process documents. This not only affects the standardization and rationalization of process documents but also brings difficulties to production in the workshop and leads to unstable product quality.
With the continuous advancement of science and technology, computer applications are gradually developing towards the CIM (Computer Integrated Manufacturing) system. In order to discuss computer-aided process development, including the automatic generation of process documents, automatic calculation of flat patterns, and automatic calculation of material consumption quotas, it is necessary to first solve the automatic determination of the bending coefficient, which is the automatic calculation of flat patterns.
Some manufacturers in the Beijing area are implementing CIM systems, but their software has not solved this problem. As for the manufacturers of CNC machine tools, the determination of the bending coefficient is a patented product and is kept confidential from the users of the machine tools. Therefore, it is necessary to independently solve the calculation method for determining the bending coefficient.
2. Theoretical Calculation of Flat Patterns
During sheet metal bending, compression occurs on the inner side while stretching occurs on the outer side. The compression on the inner side gradually decreases from the outside, and the stretching on the outer side gradually decreases from the inside. Near the center of the sheet, compression and stretching approach zero. This middle layer, where the compression and stretching are balanced, is called the neutral layer. The theoretical calculation of flat patterns is based on this neutral layer.
2.1 Bending with an Inner Arc Radius R ≥ 5t (t is the material thickness)
When the inner arc radius of the bend is greater than or equal to 5 times the material thickness, there is no thickness change in the material at the bend, and the neutral layer is located on the centerline of the material thickness.
Let b be the distance from the neutral layer to the inner wall of the sheet, a be the bending angle, T be the sheet thickness, and K be a bending factor. K = b/T, and K represents the bending coefficient of the neutral layer. During bending, the material undergoes deformation, with the outer layer being stretched and the inner layer being compressed, while the length of the neutral layer remains unchanged. Materials with higher hardness have less stretching deformation, so the neutral layer is closer to the outer side, while materials with lower hardness have greater stretching deformation, so the neutral layer is closer to the inner side. For ordinary materials, the neutral layer tends to be in the middle. In the diagram, copper and soft steel are on the left, ordinary steel plate is in the middle, and hard steel and stainless steel are on the right. The unfolded length of the material is the arc length of the neutral layer. It depends on several parameters: the bending radius, bending angle, sheet thickness, and the coefficient of the neutral layer.
The unfolded length is calculated as: DL = Pi * (R + K * T) * a / 180.
PROE also uses a Y factor to calculate the unfolded length, where Y = Pi/2 * K.
The formula becomes: DL = (Pi/2 * R + Y * T) * a / 90.
If there is no specific bending table, PROE uses this formula to calculate the unfolded length. Therefore, when starting a sheet metal fabrication, it is necessary to define the value of K or Y. The default Y value in the system is 0.5, which corresponds to soft steel and copper. If using ordinary steel plate, the K value can be set to 0.45, which is equivalent to a Y value of 0.707. "The unfolded dimensions are calculated based on the neutral layer, and the unfolded length is related to the bending die radius. Check the dimensions of the actual part after bending to identify any regular patterns, and then modify the unfolded cutting dimensions accordingly based on this experience." The neutral layer is accurate, but different practices or different groove widths of the bending die result in different bending radii, making it impossible to calculate the neutral layer. Generally, different sheet thicknesses are tested with the same groove width, and different groove widths are tested with the same sheet thickness to obtain empirical data. However, different batches of materials often have differences. Researching this problem with such an attitude will never lead to a real answer. Think about what they are answering. How can people understand if both the methods and the problems are not resolved? This is very irresponsible in terms of communication.
As technology advances, computer applications are gradually evolving towards CIM (Computer Integrated Manufacturing) systems. To discuss computer-aided process development, including the automatic generation of process documents, automatic calculation of flat patterns, and automatic calculation of material consumption quotas, it is necessary to first solve the automatic determination of the bending coefficient, which is the automatic calculation of flat patterns.
Some manufacturers in the Beijing area who are implementing CIM systems have not solved this problem with their software. As for the manufacturers of CNC machine tools, the determination of the bending coefficient is a patented product and kept confidential from the users of the machine tools. Therefore, it is necessary to independently solve the calculation method for determining the bending coefficient.
2. Theoretical Calculation of Flat Patterns
During sheet metal bending, compression occurs on the inner side while stretching occurs on the outer side. The compression on the inner side gradually decreases from the outside, and the stretching on the outer side gradually decreases from the inside. Near the center of the sheet, compression and stretching approach zero. This middle layer, where the compression and stretching are balanced, is called the neutral layer. The following calculations are based on the neutral layer.
2.1 Bending with an Inner Arc Radius R ≥ 5t (t is the material thickness)
When the inner arc radius of the bend is greater than or equal to 5 times the material thickness, there is no thickness change in the material at the bend, and the neutral layer is located on the centerline of the material thickness.
Let b be the distance from the neutral layer to the inner wall of the sheet, a be the bending angle, T be the sheet thickness, and K be a bending factor. K = b/T, and K represents the bending coefficient of the neutral layer. During bending, the material undergoes deformation, with the outer layer being stretched and the inner layer being compressed, while the length of the neutral layer remains unchanged. Materials with higher hardness have less stretching deformation, so the neutral layer is closer to the outer side, while materials with lower hardness have greater stretching deformation, so the neutral layer is closer to the inner side. For ordinary materials, the neutral layer tends to be in the middle. In the diagram, copper and soft steel are on the left, ordinary steel plate is in the middle, and hard steel and stainless steel are on the right. The unfolded length of the material is the arc length of the neutral layer. It depends on several parameters: the bending radius, bending angle, sheet thickness, and the coefficient of the neutral layer.
As shown in the diagram, the unfolded length is calculated as: DL = Pi * (R + K * T) * a / 180.
PROE also uses a Y factor to calculate the unfolded length, where Y = Pi/2 * K.
The formula becomes: DL = (Pi/2 * R + Y * T) * a / 90.
If there is no specific bending table, PROE uses this formula to calculate the unfolded length. Therefore, when starting a sheet metal fabrication, it is necessary to define the value of K or Y. The default Y value in the system is 0.5, which corresponds to soft steel and copper. If using ordinary steel plate, the K value can be set to 0.45, which is equivalent to a Y value of 0.707.
