Investigation of flexible radial ring rolling for production of non-axially symmetric seamless rings on radial axial ring rolling mills

环件轧制工艺用于生产由不同材料制成的具有广泛几何范围的无缝环件。几何柔性是该生产工艺的主要优势之一。对近净形状几何形状的需求，以降低材料和后处理成本，导致了通过应用成形工具来制造径向和轴向异形环件的工艺的发展。通过使用创新的工具和工艺控制概念，在不降低工艺灵活性的情况下增加了可生产的几何种类，成形刀具的情况就是如此。所有这些工艺变种都允许制造具有围绕其圆周的恒定横截面的异形环。还存在对圆周上具有非恒定截面的无缝环的需求，例如用于偏心轴承，但在环件轧制过程中还不能生产这些无缝环。这里描述的项目旨在进一步开发环件轧制工艺，以便能够近净形状地生产这种偏心环几何形状。这可以通过根据机器中环的圆周运动来执行芯棒的有针对性的关闭和打开运动来实现。在亚琛大学RWTH金属成形研究所的轧环机的两个导辊上已经安装了测量环件旋转的必要机构。然后，提供的信息将被传输到机器的控制中，以允许基于该信息实时控制工具的运动。此外，通过使用现有的有限元模型，通过使用上述过程控制，原则上证明了这种环几何形状的可生产性，这是以一种简化的方式完成的，使用环上的参考点来控制芯棒的运动。这里有必要将实验中使用的方法应用到仿真中，以考虑导辊(S)与套圈的潜在接触损失。在进一步的步骤中，将使用模拟来调查工艺影响和边界。在成功实施测量系统和实现刀具运动后，将通过产生两个不同高壁比的环几何形状来实验验证数值结果，并确定潜在的其他影响参数。第一个几何形状预计相对容易制造，而第二个几何形状由于环状刚度较低而显示出更窄的边界。在第二阶段，该项目的重点将是改善工艺控制，生产多个厚壁环件，以及局部不同应变对环件微观结构的影响。

The ring rolling process is used to produce seamless rings made of different materials in a wide geometric spectrum. The geometric flexibility is one of the main advantages of this production process. Demand for near net shape geometries to reduce material and post-processing costs led to the development of processes to manufacture rings profiled in radial and axial directions by applying shaped tools. By using innovative tool and process control concepts the producible geometric variety was increased without reducing the process flexibility, as is the case for shaped tools. All of these process variants allow manufacture of profiled rings with constant cross sections around their circumference. There is also demand for seamless rings with non-constant cross sections around the circumference, e.g. for eccentric bearings, but these cannot yet be produced in the ring rolling process.The project described here aims to further develop the ring rolling process in order to enable near net-shape production of such eccentric ring geometries. This can be achieved by performing a targeted closing and opening movement of the mandrel depending on the circumferential motion of the ring in the machine. A necessary mechanism to measure the ring’s rotation was already installed in both guide rolls of the ring rolling machine at the Institute of Metal Forming of the RWTH Aachen University. The provided information will then be transmitted into the machine’s control to allow for real-time control of the tool’s motions based in this information. Additionally, by use of an existing finite element model the producibility of such ring geometries was shown in principle by using the aforementioned process control, which was done in a simplified way using a reference point on the ring to control the mandrel movement. Here it is necessary to implement the method used in the experiments into the simulation to consider potential loss of contact of the guide roll(s) with the ring. In further steps, process influences and boundaries will be investigated by use of the simulation. After successful implementation of the measurement system as well as realisation of the tool motions the numerical results will be verified experimentally by producing two ring geometries with different height-to-wall thickness ratios and potential additional influencing parameters will be identified. The first geometry is expected to be comparatively easy to produce while the second geometry shows more narrow boundaries resulting from a lower ring stiffness. In a second phase the project’s focus will be improvement of the process control, production of rings with several thick sections and the effect of locally different strains on the microstructure of the rings.