DETERMINATION OF THE K-FACTOR FOR BENDING OF AISI 304 SHEET MATERIAL

Abstract

The aim of this study is to determine the k-factor, which plays an important role in sheet metal bending processes, which are frequently applied in the automotive and defense industries. The mentioned k-factor is used to calculate the length to be cut in laser cutting before bending, so it must be determined correctly in order to perform the bending process within the tolerance range. Some equations are used to find the k-factor. However, these equations are theoretical and have differences with real twists. This may sometimes not be a problem for parts with only one twist. But problems are encountered with multiple twists. Because the length of the sheet metal after laser cutting cannot be extended again. Cutting operations are not precise and increase labor costs. It also causes loss of time. Although there are some exceptions, the k-factors of all sheet materials are expected to be different. Each company should first determine the materials it uses and determine their k-factors through experimental studies. Designs must be made according to the k-factors found. The wear on the dies and the usage time of the twisting machine should not be ignored. Abrasions are a factor that prevents accurate and precise bending. For this reason, maintenance work on the dies and twisting machine must be carried out regularly. In the literature, there is very limited information about the thickness-dependent k-factor of AISI 304 stainless steel sheet materials. Generally, studies have been carried out on calculating the amount of springback in bending and accordingly the required bending forces, comparing the k-factors found using different upper and lower molds, and calculating the k-factor using software programs such as C++. In this study, the values of k-factor that should be used in bending processes of the specified sheet material up to 4 mm thickness were determined.

Bu çalışmanın amacı otomotiv ve savunma sanayinde sıklıkla uygulanan sac levha büküm işlemlerinde önemli bir rol oynayan k-faktörünün belirlenmesidir. Söz konusu k-faktörü, parçanın bükümden önce lazer kesimde hangi boyda kesileceğini hesaplamada kullanılmakta olup, dolayısıyla tolerans aralığında büküm işleminin gerçekleştirilebilmesi için doğru belirlenmesi gerekmektedir. Literatürde, AISI 304 paslanmaz çelik sac malzemelerin kalınlığa bağlı k-faktörü ile ilgili kısıtlı bilgi bulunmaktadır. Bu çalışmada, belirtilen sac malzemenin 4 mm kalınlığa kadar büküm işlemlerinde kullanılması gereken k-faktörü değerleri belirlenmiştir.