Use of cement concrete as a homogenous material and as a composite material in the machine tool design

机床的结构部件（如床身、立柱和十字滑块）主要由钢或铸铁制成。这些材料表现出良好到非常好的强度特性。由于上个世纪初资源稀缺，人们首次尝试用（钢增强）混凝土代替钢。在20世纪70年代，更严格的材料要求导致了新型替代材料的发展。当时，反应树脂混凝土比水泥基混凝土更受青睐。如今，由于水泥混凝土成本低、阻尼性能好、密度低，人们越来越希望使用水泥混凝土。经典水泥混凝土的进一步发展被称为超高强度混凝土（UHSC）。与钢相比，UHSC在抗拉强度方面仍显着不足，这在特定应用的设计中必须考虑。在机床和生产系统制造业中已经进行了UHSC的首次尝试。然而，由于缺乏基础研究，市场上的广泛接受仍然不存在。该研究项目的总体目标是调查水泥混凝土在机床中的使用可能性，无论是作为纯材料还是复合材料，都能够利用其出色的经济和机械性能，尽管它存在弱点。为此，应建立材料与要求标准或单个零件与要求标准之间的联系，并在此基础上制定机床行业高性能混凝土框架部件的设计指南。在第一个研究阶段，创造了在机床工业中有目的地使用水泥混凝土的初步科学基础。除了制定要求标准外，还对原材料进行了固体材料特性和动态疲劳强度的研究。详细分析了包括拉杆在内的连接点和连接方式对其疲劳强度的影响。一个由水泥混凝土制成的性能良好的组件（床和移动柱）被创建，并以焊接钢结构为基准。由于非常有希望的结果，对机床水泥混凝土框架组件面向应用设计的装配和材料技术优化潜力的进一步研究将进入第二个研究阶段。

Structural parts for machine tools (e. g. beds, columns and cross-slides) are predominantly made from steel or cast iron. These materials exhibit good to very good strength properties. Due to scarcity of resources during the beginning of the last century, a first attempt was made to substitute steel by (steel-reinforced) concrete. More stringent material requirements during the 1970s led to the development of novel substitution materials. At that time, reaction resin concrete was favored over cement-based concrete. Today, the use of cement concrete is increasingly desired, due to its low cost, good damping qualities and low density. A further development past the classical cement concrete is called ultra-high strength concrete (UHSC). In comparison to steel, UHSC still significantly lacks in tensile strength, which has to be considered during the application-specific design. First attempts with UHSC were already made in the machine tool and production systems manufacturing industry. However, due to missing fundamental research, a widespread acceptance on the market is still non-existent.The overall goal of the research project is the investigation into usage possibilities of cement concrete in machine tools, both as a pure and composite material, to be able to utilize its excellent economical and mechanical properties despite its weaknesses. To this end, connections between the material and the requirement criteria or individual parts and the requirement criteria shall be established, on the basis of which the development of guidelines for the design of high-performance concrete frame components for the machine tool industry could be established.Within the first research phase, initial scientific fundamentals for a purposeful usage of cement concrete in the machine tool industry were created. Aside from deriving requirement criteria, the raw material was investigated, regarding the solid material characteristics and the dynamic fatigue strength. Coupling points and methods including tie rods were analyzed in detail towards their fatigue strength. A well-performing assembly (bed and moving column) made from cement concrete was created and benchmarked against a welded steel construction.Due to the very promising results, a further investigation into the assembly and material technology optimization potentials for an application-oriented design of cement concrete frame components for machine tools is targeted in a second research phase.