Research For The Performance Analysis Of Rotary Joint In Extremely-cold And Large-Temperature Difference Environment And Design Of A Self-adaptive Structure

In recent years,robots and mechatronics equipment have been widely used in special unstructured environments,such as construction,mining,risk elimination,military,service,agriculture,and extreme environments,such as space exploration,ocean development and polar exploration.But the research on mechanical system and robots in extremely-cold and large temperature-difference environment is very little,and the research on mechanism characteristics in extreme environment is also very limited.The mechanical equipment,robots,or complex mechanical systems in polar,plateau scientific research or aerospace field need to maintain good working performance in extreme environment,and the thermal deformation caused by low temperature environment and large temperature difference will change the matching relationship and geometric characteristics of mechanical parts,so it cannot work in the ideal state of design.Therefore,it is very important to study this problem and puts forward reasonable solutions for the operation accuracy of mechanical system in extremely cold and large temperature-difference environment,and it is also one of the key factors to improve its stability and working life.This paper first introduces the theoretical basis of extremely cold and large temperature difference analysis,and uses thermo-elasticity to calculate the parts under the condition of temperature change,to prepare for the following complex analysis.Then,a kind of specific temperature change and distribution with practical significance is proposed,and the material is determined,and the specific mathematical model is built and calculated,to get the influence on the interior of the rotary joint in the extremely cold and large temperaturedifference environment.The theoretical analysis and calculation are given for this condition.Finally,ANSYS Workbench is used to simulate and analysis the stress,strain,and deformation of the bearing fitting in the extremely cold and large temperature difference environment under the steady-state thermal conditions.Based on the characteristics for generating of thermal stress under the above-mentioned specific conditions,aiming at the design requirements and working principle for the auxiliary structure of temperature change adaptive compensation for rotary joints,two types of reliable adaptive structure schemes are proposed.The three-dimensional model of the adaptive structure is established by using CREO,and the advantages and disadvantages of those two schemes are compared and analyzed.Then the internal details of the structure are analyzed and optimized,and a simple overall structure,stable and effective operation scheme is finally determined.Then,the change of the inner raceway space of the bearing at the rotating joint under the extremely cold and large temperature difference and the change of the bearing friction torque caused by it are analyzed,to explain the urgent need to improve the performance of rotating joint under the extremely cold and large temperature difference environment in the specific application,to avoid the problems.Then,the force and function of the adaptive structure designed above in changing temperature difference are explained in detail,and then the kinematics verification is carried out by using ADAMS.It can be found that this structure overcomes the influence of thermal stress caused by extremely cold and large temperature difference on the operation of the rotary joint,avoids the low transmission accuracy under high temperature and the stagnation phenomenon in low temperature,and improves the motion accuracy and transmission efficiency of the rotary joint in extremely old and large temperature difference environment.Finally,the design of the experimental device is explained,and the specific measurement principle,experimental steps,experimental process,and results are described and analyzed.Finally,the conclusion is drawn that for the rotation joint movement in extremely cold and large temperature difference environment,due to the influence of temperature load on the operation,the designed adaptive structure can effectively reduce the gap produced and friction torque changes,to improve the rotation performance,the operation accuracy and efficiency.