7 Replies Latest reply on Feb 15, 2018 12:06 PM by Elmar Klammer Branched to a new discussion.

    Bend_Calculation Table Variables?

    Derek Eldridge

      In the bend_calculation.xls, does anyone know what the "lg" represents in the k-factor equation?

       

        • Re: Bend_Calculation Table Variables?
          Dennis Dohogne

          This isn't a direct answer to your question, but attached is information I put together to explain K-factors and a spreadsheet to facilitate data collection for calculating your own.

            • Re: Bend_Calculation Table Variables?
              Derek Eldridge

              Thank you Dennis.

              I did see your attachments on two other posts.

              My sheet metal shop uses bend deduction. They have not shared a full table. And when i'm bedding at various angles, without the K factor or deduction values, I don't want to have to add a line every time I use another angle. I've had better luck with the calculation table. At least to quickly complete mockups. Then the shop adds the info they need when I give it to them.

               

              My question is to better understand what Solidworks is actually doing in that file.

            • Re: Bend_Calculation Table Variables?
              Kevin Chandler

              Hello,

               

              I believe it's supposed to be "log".

              As you deviate from the theoretical inside radius = sheet thickness (log(1) = 0), it adjusts the 0.65 value by 1/2 of the log ratio.

               

              Cheers,

               

              Kevin

               

              EDIT: Here's the equation graphed:

              • Re: Bend_Calculation Table Variables?
                Elmar Klammer

                Hi Derek,

                 

                That's a bend table as per DIN 6935 - Cold bending of flat rolled steel.

                The formula is correct. "lg" stands for log(10).

                L = a + b + v

                Elmar

                  • Re: Bend_Calculation Table Variables?
                    Derek Eldridge

                    Thank you both Kevin Chandler and Elmar Klammer.

                    I think you're both right. Elmar, thank you for clarifying the source.

                    Now, looking at DIN6935, I want to list all the variables in case someone else has a similar question for other variables in this sheet. They are not all defined in SolidWorks bend_calculation.xls, and there are a couple conflicting variables representing the greek notation.

                     

                    DIN 6935:2011-10

                    α = Bending angle (DIN6935)

                    ß = Opening angle (DIN6935)

                    b = Leg length (DIN6935)

                    b = ß (Solidworks "bend_calculation.xls")

                     

                    a = Leg length (DIN6935)

                    a = α (Solidworks "bend_calculation.xls")

                     

                    Bend Angle = ß = 180-α (Solidworks "bend_calculation.xls")

                     

                    v = Compensating value (DIN6935 & Solidworks "bend_calculation.xls")

                    Developed length = a + b + v  (DIN6935)

                    k = Correction Factor or k-factor (DIN6935 & Solidworks "bend_calculation.xls")

                     

                     

                      • Re: Bend_Calculation Table Variables?
                        Elmar Klammer

                        Hi Derek,

                         

                        I don't know of any other standard like this for Alu or or other steels. It's fairly old and was re-issued in 2011 with minor cosmetic updates.

                        That's a official standard and you are technically not supposed to copy sections out. But I think showing the sketch is okay.

                        The leg measurements change depending on the bend angle range (use tangent length setting)

                         

                        The formula works best only between r/s of 0.8...5

                        For r/s > 5                  you use a correction factor k of 1

                        For r/s 0.25 ... 0.8      you can use the formula with some restrictions as seen from graph below.

                        For r/s <0.2                you use a correction factor of 1

                         

                         

                      • Re: Bend_Calculation Table Variables?
                        Derek Eldridge

                        Elmar Klammer, do you know of an aluminum version of that standard? Or any other material for that matter?