Pipes are widely applied across many industries such as the automotive, aerospace and air conditioning industries. With the development of industrial technology, various pipe materials and various pipe shapes are produced according to the purpose. Many researchers have been studied pipe bending technology to meet these diverse needs, and among them, the long-type elbow is a typical one that changes the moving direction of fluid or gas among various pipe types. Many researchers work on the pipe segment. In-process push-bending used in pipe bending is a bending process where a cut pipe is inserted into a die. Push-bending is effective for reducing the weight of parts that do not induce material loss, but the process is more complicated than the draw-bending process. In this study, we proposed an analytical model for a push-bending process in which a joint type mandrel was added to a long-type elbow made of C1220 material for weight reduction. The forming analysis is to verify the experiment by comparing the analysis result and the experimental result through the forming analysis software DEFORM to confirm the change of the wrinkle and the thickness of the bent pipe. In addition, we confirmed the wrinkling of the bent pipe and the die non-contact phenomenon depending on the angle and position of the joint mandrel and presented the optimum angle and center of gravity position of the joint mandrel using the experimental design method.

管道广泛应用于许多行业，例如汽车，航空航天和空调行业。随着工业技术的发展，根据目的生产各种管道材料和各种管道形状。许多研究人员已经研究了弯管技术来满足这些多样化的需求，其中长型弯头是一种典型的弯管，它可以改变各种类型的管道中流体或气体的移动方向。许多研究人员致力于管道部分。管子弯曲中使用的过程中弯曲是将切割管插入模具的弯曲过程。推弯有效地减轻了不引起材料损失的零件的重量，但是该过程比拉弯过程更复杂。在这个研究中，我们提出了一种推弯过程的分析模型，其中将接头型心轴添加到由C1220材料制成的长型弯头中以减轻重量。成形分析是通过将分析结果与通过成形分析软件DEFORM进行的实验结果进行比较来验证实验，以确认折皱和弯管厚度的变化。另外，我们确认了弯管起皱和模具非接触现象取决于接头芯轴的角度和位置，并通过实验设计方法给出了接头芯轴的最佳角度和重心位置。成形分析是通过将分析结果与通过成形分析软件DEFORM进行的实验结果进行比较来验证实验，以确认折皱和弯管厚度的变化。另外，我们确认了弯管起皱和模具非接触现象取决于接头芯轴的角度和位置，并通过实验设计方法给出了接头芯轴的最佳角度和重心位置。成形分析是通过将分析结果与通过成形分析软件DEFORM进行的实验结果进行比较来验证实验，以确认折皱和弯管厚度的变化。另外，我们确认了弯管起皱和模具非接触现象取决于接头芯轴的角度和位置，并通过实验设计方法给出了接头芯轴的最佳角度和重心位置。