锻造操作机钳口夹持力研究

In recent times, the study and analytical calculation of the forging manipulator's jaw was based on friction of jaw's gripping rigid axle workpiece while neglecting the crowned-tooth construction on the jaw and workpiece's contact surface and a condition of the workpiece's high-temperature. Because of the difficulties in confirming friction factor in the friction-based gripping force calculation and theoretical calculation is too inaccurate to guide the designing process, this paper is trying to separate jaw's gripping process into the clamping condition to make the plastic deformation extrusion mark on the workpiece and the gripping condition when supporting the gravity and heavy torque of the workpiece and performing the operating action to do a theoretical analysis on jaw's gripping force basing on the actual process and contact condition of jaw gripping workpiece and a research group's output of a simplification of action between gripping mechanism's jaw and forging's contact surface to the action between jaw's crowned tooth and forging's extrusion groove in confirming gripping force. To clear the jaw's gripping mechanics and explore the effect to the gripping force with manipulator jaw's angle, the contact length between jaw and workpiece and the construction and distribution of crowned-tooth construction on the jaw and workpiece, it needs to consider the structure characteristic of jaw and the gripping process, the contact characteristic and friction factor as a whole to find a gripping force's calculating method that fits the working condition , give full play to the device's potential and give a theoretical basement to the research of heavy-load forging manipulator for extreme manufacture and optimal design of small and medium-sized manipulator.

目前，锻造操作机以忽略钳口与锻件接触表面的凸齿结构和锻件的高温状态,基于钳口夹持刚性轴类锻件的摩擦抓取进行钳口夹持研究和分析计算。针对基于摩擦抓取进行夹持力计算存在的摩擦因数确定困难、理论计算误差大难以有效指导设计等问题，依据钳口夹持锻件的实际过程和接触状态，结合课题组将钳口与锻件之间简化为凸齿与挤压槽作用确定夹持力的研究成果，本课题拟将钳口夹持过程分为使锻件产生塑性变形挤压痕的夹紧状态和钳口承受锻件重力及重力矩并执行操作动作的夹持状态对锻造操作机进行钳口的夹持力理论分析。统筹考虑钳口结构特点、钳口与锻件的夹持过程和接触特点、摩擦因数等问题，明确钳口夹持机理；探索锻造操作机钳口夹角、钳口与锻件的接触长度、钳口与锻件接触表面凸齿结构及分布等因素对夹持力的影响规律；研究更为符合应用工况并使设备充分发挥潜能的夹持力计算方法；为极端制造所需的巨型重载操作机研究和中小型操作机优化设计提供理论依据。

钳口所需夹持力既是锻造操作机结构设计的前提，也是操作机理论分析的薄弱环节，确定符合应用工况的钳口夹持力已成为重载锻造操作机研究的关键问题。. 课题围绕操作机的夹持状态，研究了钳口与工件的夹持机理，建立了两种不同研究思路的钳口夹持力学模型，研究了锻造操作机钳口的夹持力确定方法，比较分析了两种不同力学模型对确定钳口夹持力的影响，明确了以允许工件下垂偏转建立力学分析模型的合理性，确定了锻造操作机钳口最小稳定夹持力的理论分析方法。研究了影响最小稳定夹持力的关键参数，阐述了关键参数的确定思路，为锻造操作机结构设计提供了条件。. 针对操作机“冷”钳口与“热”工件的接触特点，实验研究了摩擦因数随温度变化的规律，明确了锻造操作机夹持过程的最小摩擦因数，分析了最小摩擦因数对钳口夹持状态的影响，确定了钳口与工件接触表面采用凸齿结构的作用和必要性，以当量摩擦因数体现了操作机钳口与工件的接触面特点，为合理确定两者间的摩擦因数提供了依据。. 在理论分析的基础上，构建了钳口夹持实验装置，研究了钳口最小稳定夹持力确定方法的可靠性。钳口静动态夹持实验测试表明，以“允许工件下垂偏转”确定钳口的夹持力能够满足锻造操作机的稳定工作，理论分析结果有较强的可靠性，符合锻造操作的使用要求。. 为充分发挥锻造操作机的夹持能力，结合钳口夹持力的研究成果，分析了钳口销轴中心距对操作机所需夹持力的影响，研究了锻造操作机的典型夹持工况，明确了操作机夹持装置近恒力输出的必要性。综合考虑夹持装置对操作机其它部件的影响，确定了夹持装置的整体结构。根据夹持装置的结构特点，研究了夹持装置的传力比，分析了夹持装置的关键参数和确定方法，确定了近恒力输出夹持装置的设计思路。并以30T和60T操作机为例，对原机构和近恒力输出机构进行了比较分析，确定了研究成果的可行性，为锻造操作机夹持装置的结构设计和理论研究提供了条件。.