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绍、铜、某些种类的黄铜以及其它金属和合金由于具有高塑性,故能够用高速度热挤压。同时,低塑性的有色金属合金也能够在一定的温度和速度范围内热挤压。不遵守合适的温度—速度制度会使挤压件产生裂纹,这是由于金属从模子中出来时的纵向拉应力所引起的。纵向拉应力是内外层金属流动速度的不同与外摩擦阻力引起的。为了消除废品和达到最大可能的生产率,必须调节挤压的温度—速度制度。大部份现有的带水泵—蓄力器传动系统的液压机
Shao, copper, some kinds of brass and other metals and alloys can be hot-extruded at high speed due to their high plasticity. At the same time, low-ductility non-ferrous metal alloys can also be hot-extruded at a range of temperatures and speeds. Failure to comply with a suitable temperature-speed regime can cause cracks in the extrusion due to longitudinal tensile stresses on the metal as it emerges from the mold. Longitudinal tensile stress is the difference between the inner and outer metal flow velocity and external friction resistance. In order to eliminate rejects and to achieve the maximum possible productivity, the temperature-speed system of extrusion must be adjusted. Most existing hydraulic machines with pump-accumulator drive systems