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、立柱和横滑板)主要由钢或铸铁制成。这些材料表现出很好的到非常好的强度性能。由于上个世纪初资源的稀缺，人们第一次尝试用钢筋混凝土代替钢。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。目前，水泥混凝土因其成本低、减震性能好、密度小等优点，越来越受到人们的青睐。在经典水泥混凝土基础上的进一步发展被称为超高强混凝土(UHSC)。与钢相比，超高强度混凝土在抗拉强度方面仍然明显不足，这一点必须在具体应用的设计中加以考虑。与UHSC的首次尝试已经在机床和生产系统制造行业进行。然而，由于缺乏基础研究，市场上仍然没有得到广泛的接受。该研究项目的总体目标是调查水泥混凝土作为纯材料和复合材料在机床中的使用可能性，以便能够利用其优异的经济和力学性能，尽管它存在弱点。为此，应建立材料与要求标准或单个部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。在第一研究阶段，为有目的地在机床行业使用水泥混凝土奠定了初步的科学基础。除了得出要求标准外，还对原材料进行了调查，包括固体材料特性和动态疲劳强度。详细分析了包括拉杆在内的连接点和方法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(床和移动立柱)已经被制造出来，并与焊接的钢结构进行了对比。由于非常有希望的结果，第二个研究阶段的目标是进一步研究面向应用的机床水泥混凝土框架组件的组装和材料技术优化潜力。

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.