In the top-down design process of part, with the continuous introduction of domain knowledge, the design state is gradually progressively transformed. In order to construct the normalized evolution process of part from function to structure, the mapping relationship between part function and structure constraint was analyzed, the transformation process of part design state was fully expressed, and the progressive multi-domain view model of part from function to structure semantics, part reduction structure to detailed structure was defined. Through the analysis of functional constraint, topological structure and functional relationship of the part model, and the analysis of functional time sequence, functional unit, geometric structure, shape and position, assembly and evolution sequence of the part component unit, the part association constraint model based on functional constraint and structural constraint was established, and the abstract semantic knowledge was structured. Therefore, a top-down progressive multi-domain view model of part was constructed, which was composed of function view model, semantic description model of function structure transition, structure reduction view model and structure view model. According to the expression levels and requirements of part feature information, the above view models were expressed to reflect the design knowledge in different forms and stages of part, and thus a part object definition model with characteristics of process, dynamic, hierarchical and progressive evolution was formed. Based on the multi-domain view model, multiple interpretations of the part structure could be formed, so as to realize the function-driven serial design of the part structure, expand the narrow scope of the part structure design, help to realize the model-based computer-aided part design, and promote the automation and intelligence of the product design process.

The two-stage hydro-mechanical continuously variable transmission can realize continuously variable transmission with large transmission ratio and wide transmission range, reduce the rated power of hydraulic components and improve the whole transmission efficiency. The kinematic characteristics of the transmission mechanism are related to the setting of the working mode and the performance of the whole vehicle. This paper analyzed three types of split and confluence forms of hydro-mechanical continuously variable transmission mechanism: the split-torque confluence-speed type, the split-speed confluence-speed type and the split-speed confluence-torque type. Using the lever method, the influence of the position of external force components on the distribution of mechanical points, the positive and negative phases of hydraulic components and the power split type were studied, and the feasible form of split and confluence of the two-stage hydro-mechanical continuously variable transmission mechanism was obtained. The relationship between the rotation speed of hydraulic components and the output rotation speed in each segment was summarized, and the connection law of the output rotation speed between segments was studied based on the theory of no speed difference range-shift. Through the round-trip change of the positive and negative phases of the hydraulic components, the continuous variable variation of the output rotation speed of the two-stage hydro-mechanical continuous transmission was realized. A simulation platform of ZL50 loader was built, which adopted the hydro-mechanical continuously variable transmission of the split-torque confluence-speed and split-torque confluence-speed. The movement characteristics of the loader under typical V cycle working conditions were simulated, and the output torque and transmission efficiency of the transmission was analyzed. The result verified the correctness of the theoretical analysis result. The research reveals the motion characteristics of the hydro-mechanical continuously variable transmission mechanism and the motion connection law between the segments, which provides a theoretical basis for the design and engineering application of the hydro-mechanical continuously variable transmission mechanism.

Roundness error is an important parameter to evaluate the machining accuracy of machine tools. In order to realize the evaluation of the roundness error measurement uncertainty of machine tools, the contributing factors and uncertainty evaluation method of the machine tool roundness error based on the ballbar measurement are studied. Firstly, the least square method (LSM) was used to evaluate the roundness error. Secondly, a multi-source fusion error measurement uncertainty evaluation method was proposed based on the black box theory. Thirdly, according to the basic principle of machine tool roundness error measured by the ballbar, an evaluation model of machine tool roundness error measurement uncertainty was established. Finally, multiple sets of repeated measurement experiments on the roundness error of the ZX plane of a machining center were carried out by the ballbar, and the roundness error measurement uncertainty was calculated by the proposed method, which was compared with the calculation results based on the Monte Carlo method (MCM) for verification. The results showed that the roundness error uncertainty evaluation results of the machine tool based on the proposed method and MCM were 1.190 0 and 1.160 0 μm, respectively, and the relative deviation was about 2.5%, which verified that the feasibility of the proposed method. The proposed method avoids the complicated process of solving the functional relationship between inputs and outputs, and simplifies the evaluation process of the roundness error measurement uncertainty of machine tools, which has strong practicability.

The pipeline creeping mechanism based on 3-(P)URU(P) parallel mechanism can realize the creeping in the pipeline by alternately releasing the moving and fixed platform and 3 URU branch chains connected to the two platforms, so it can be applied to the monitoring and flaw detection of industrial and agricultural transportation pipeline. The singularity of the mechanism will affect its efficiency and engineering quality, so a singularity analysis method of mobile parallel mechanism was proposed, and the singularity of the mechanism was studied. Firstly, according to the screw theory and the line geometry method, the configurations of branch chain singularity, constraint singularity and drive singularity were analyzed; then, the singularity of the mechanism in the creeping process in the pipe was analyzed. The results showed that the branch chain singularity of the mechanism occurred in the elbow pipe, which led to the reduction of the degree of freedom and even the blockage in the pipe, and the constraint singularity occurred in the straight pipe, which led to the uncontrollable creeping; finally, the constraint equations were established according to the constraint relationship of mechanism singularity, and the respective singular trajectories were obtained by numerical simulation. The research results provide an important theoretical basis for the follow-up design and engineering application of the mechanism control system.

In order to accurately simulate the placement task of users in VR (virtual reality) environment and avoid the low placement accuracy caused by the shaking of interaction devices, the interaction was carried out by using natural gestures. A prediction method of natural gesture interaction time for VR placement task based on improved Fitts Law was proposed. Firstly, the interaction logic of "gesture interaction-VR environment-VR interaction task" was constructed to establish the semantic mapping relationship between natural gesture and interaction task; secondly, according to the design principle of natural gesture, the natural gesture interaction experiment for VR placement task was carried out; then, combined with the characteristics of VR placement task, the moving distance, target tolerance and the size of the moving object were integrated into the classical Fitts Law, and the prediction model of natural gesture interaction time based on improved Fitts Law was established; finally, the regression analysis of the experimental data was carried out. It was found that the correlation coefficient R²=0.515 by fitting based on the classical Fitts Law, and there was a large deviation between the predicted value and the real value of interaction time, which indicated that the classical Fitts Law was not suitable to predict the natural gesture interaction time for VR placement task; the correlation coefficient R²=0.970 based on improved Fitts Law, and the predicted value of interaction time was consistent with the real value, which showed that improved Fitts Law had good applicability and could accurately predict the natural gesture interaction time for VR placement task. The research results enrich the VR interaction mode, and can provide guidance for the design of human-computer interaction interface in VR environment.

The large number of indirect contact between people in the narrow space of the box elevator has brought hidden dangers to the spread of COVID-19 (Corona Virus Disease 2019). How to inhibit the survival and spread of the virus in the elevator has become an urgent problem to be solved. Therefore, by analyzing the advantages and disadvantages of axiomatic design (AD) and Tteoriya Resheniya Izoblateskikh Zadatch (TRIZ), an innovative design method integrating AD and TRIZ was proposed for different design types, such as breakthrough design, adaptive design and variable parameter design. Firstly, the function requirements of the product were analyzed to determine its design type, and the function requirements was decomposed by the AD theory, and the function-structure tree was constructed by the TRIZ. Then, the coupling judgment of the initial design scheme was carried out, and the TRIZ was used to decouple. After several iterations, the final design scheme was obtained. Taking the public interactive control panel and the enclosed car of the traditional box elevator as the research object, facing the function requirements of preventing virus transmission and eliminating virus, the innovative design method integrating AD and TRIZ was adopted to design the epidemic prevention function module of the box elevator, and the non-public contact interactive control module and the conditional disinfection and sterilization module for the traditional box elevator were designed. The innovative design example made a beneficial attempt to expand from the traditional mechanical structure design to the new human-computer interaction mode design, which verified the feasibility of the innovative design method integrating AD and TRIZ. The research results can provide effective theoretical support for the conceptual innovative design of new functional modules of products.

The rigidity of the tandem machine tool is restricted by the weakest module with the smallest rigidity. In order to improve the rigidity of the machine tool, a new method for identifying weak modules of the machine tool is proposed. Firstly, the modular design method was used to divide the machine tool into modules. Then, the smallest module including the spindle was taken as the basic module, and the modules in the same series structure were added one by one; by analyzing the deformation increment of the structure after adding a module, the weak module of the machine tool was determined. Finally, the structure of the identified weak module was improved. Taking the overall quality, X, Y, Z direction deformation and dynamic characteristics of the machine tool as evaluation indexes, the fuzzy comprehensive evaluation method based on the entropy weight method was used to compare the performance of the machine tool before and after structure improvement, so as to verify the feasibility of the proposed method. The results of weak module identification example of the C-type friction stir welding machine tool showed that, the proposed method could not only accurately identify the weak module of the machine tool, but also accurately obtain the weak direction of the weak module. The research results can lay a theoretical foundation for the improvement of machine tool structures.

Screw motor is the power source of the screw drilling tool, and the reasonable design of interference between the stator and the rotor is very important for the working performance and service life of the motor. Firstly, a two-dimensional meshing finite element model of the stator and the rotor of the screw motor was established, and the influence of working pressure and bottom hole temperature on the stator profile was analyzed. Then, based on the evaluation criterion of sealing performance, the contact stress of the stator and the rotor under different interference was calculated, and a non-uniform interference design method with different interference at the large and small diameters of the stator was proposed. Finally, based on the rotor of the screw motor, the stator profile considering the influence of pressure and temperature was designed, which theoretically realized the effective sealing and good contact between the stator and the rotor. The bench test results of the screw drilling tool showed that, compared with the common interference design method, the non-uniform interference design method considering the influence of pressure and temperature could make the screw motor have higher efficiency. The research results can provide a certain reference for the design of the interference and other parameters of screw motors.

In order to solve the problem of low straightening accuracy and low standardization in manual straightening of cable, the finite element simulation and experimental analysis of straightening process of a new type of power cable were carried out, and the change rule of cable deflection in the process of cable straightening was studied. The finite element model of semi-circular cable was established by ANSYS workbench software, and the cable straightening situation when the indentation amount was 0.5 mm was analyzed by instantaneous dynamic; on this basis, the straightening process of the cable under the same feed speed, different inner diameter of the cable, the same inner diameter of the cable and different feed speed was analyzed, and the relationship between the cable deflection and the inner diameter and feed speed of the cable was studied; the bending cable sample was prepared and the straightening experiment was carried out. The results showed that the straightening result of the cable was in line with the expected result under a given indentation amount of 0.5 mm; the inner diameter and feed speed of the cable had great influence on the cable deflection. The larger the cable inner diameter was, the faster the feed speed was, the larger the cable deflection was, the lower the straightening accuracy was, and the deflection variation trend was nonlinear. The error between the simulation value and the experiment value was within 10%, which verified the accuracy of the finite element model of cable straightener. The research results can provide a reference for improving the straightening accuracy, work efficiency and optimal design of cable straightener.

Dual clutch transmission (DCT) has advantages of fast shifting speed, high transmission efficiency and low mass. The power and economy of electric vehicles equipped with DCT can be significantly improved. In the DCT, the design of the electro-hydraulic control system assembly is particularly critical. Taking the two-speed dry dual clutch transmission (referred to as 2DCT) of a pure electric vehicle as the research object，the electro-hydraulic control system assembly was designed. Firstly, based on the structure and performance parameters of the dry dual clutch in the 2DCT, the key components of the 2DCT electro-hydraulic control system were selected and calculated. Then, based on the principle of 2DCT electro-hydraulic control system, the integrated hydraulic valve body was designed, and its structural stability was verified by the statics analysis. Finally, the structure of the integrated hydraulic valve body of 2DCT electro-hydraulic control system was topologically optimized to reduce the mass of the hydraulic valve body, so as to achieve lightweight. The results showed that the working characteristics and structural strength of the designed electro-hydraulic control system assembly both met the requirements, which could fully improve the ride comfort and response speed of electric vehicles. The research results can provide a theoretical basis for the development of the electro-hydraulic control system assembly of electric vehicle transmissions.

Aiming at the problem of high internal resistance of electromagnetic coils and low working efficiency of engine caused by high working temperature of electromagnetic coils of electromagnetic engine, the heat transfer performance of water cooling system was studied by fluid-solid coupling heat transfer theory. Taking the fluid field and solid field of water cooling system of electromagnetic engine as the research objects, a mathematical model of fluid-solid coupling heat transfer was established; by UG (Unigraphics) software, the fluid-solid coupling model of water cooling system was established, which was used to simulate and analyze the distribution of flow field and temperature field of water cooling system. The results showed that the fluid in the dead zone of the water cooling system would increase the motion resistance of the surrounding fluid and decrease its velocity; the cooling water jacket was made of aluminum alloy with good thermal conductivity, which could improve the heat dissipation capacity of no flow zone; the inlet and outlet of water jacket adopted diagonal structure design, which could make the heat absorption of water cooling system more uniform. According to the relevant standards of the automobile industry, the temperature rise experiment was conducted, and the temperature of the key parts of the water cooling system was tested. The results showed that the temperature at the water inlet was 26.4 ℃, and the maximum temperature at the water outlet was 46.7 ℃, which showed that the cooling system design was reasonable, and it had a better heat transfer and cooling effect. The designed water cooling system of electromagnetic engine has a wide application prospect in the field of new energy vehicles.

Bolts are the key fasteners of slewing bearings. In order to investigate the influence of working parameters of fastening bolts on the load distribution of the slewing bearing, a finite element equivalent modeling method for the three-row roller slewing bearing is proposed. Firstly, based on the structural characteristics and stress conditions of the three-row roller slewing bearing, a finite element model of the slewing bearing considering fastening bolts was established. From the aspects of reducing the calculation amount and ensuring the calculation efficiency, the non-linear spring element was used to simulate the roller, and the load distribution of the slewing bearing was quickly obtained through the finite element simulation. Then, the static loading experiment for the three-row roller slewing bearing was designed and carried out. By comparing the finite element simulation results with the experimental results, the accuracy of the constructed finite element model was verified. Finally, based on the constructed finite element model, the influence of the bolt preload and the friction coefficient of bolt joint surface on the load distribution of the three-row roller slewing bearing was analyzed. The simulation results showed that the bolt preload had a significant effect on the load distribution of the three-row roller slewing bearing, while the friction coefficient of bolt joint surface had a weak effect; the maximum load of the upper row roller increased with the increase of the bolt preload, and the maximum load of the lower row roller decreased with the increase of the bolt preload; under the combined action of axial force and tilting moment, the load of the lower row roller of the three-row roller slewing bearing was generally higher than that of the upper row roller, so the sufficient bolt preload could improve the bearing capacity of the slewing bearing, while the insufficient bolt preload would make the lower row roller bear more load, leading to the premature failure of the slewing bearing. The research result can provide reference for the installation and maintenance of slewing bearings.

In order to study the vibration characteristics of shearer sliding shoes, the dynamics modeling analysis of the whole shearer is carried out. Firstly, according to the functions of shearer components, the shearer was divided into nine parts: front and rear drums, front and rear rocker arms, fuselage, front and rear guide sliding shoes and front and rear smooth sliding shoes; then, based on the Lagrange method, the three-directional coupling dynamics model of the shearer was constructed; then, the coordinate coupling problem of the constructed dynamics model was analyzed, and the Wilson-θ algorithm was used to solve the dynamics model; finally, the three-directional vibration acceleration of the sliding shoe was obtained through the shearer vibration experiment and compared with the simulation results. The results showed that the median vibration accelerations of the sliding shoe obtained through the simulation and experiment were concentrated at the balance position "0 m/s²", but the quartile full range of simulation results was larger than the experimental results, that was, the simulation results were relatively divergent, while the experimental results were more aggregated; the correlation coefficients between simulation results and experimental results were both greater than 0.3, showing a real correlation, and the correlation coefficients of some data were greater than 0.5, showing a significant correlation; in the P value histogram of simulation results and experimental results, the P value of each group of data was greater than 0.05, which indicated that there was no significant difference between the simulation results and experimental results within the 95% confidence interval, so the simulation results could approximately replace the experimental results and they had a certain accuracy and practicability. The research results can provide theoretical basis for the fault diagnosis, structure optimization and fatigue life analysis of shearer sliding shoes.

In order to solve the problem that the paper-plastic composite bag is easy to wrinkle during the correction transmission, a magnetic compression correction device was designed. Firstly, the structure of the magnetic compression correction device for paper-plastic composite bag was designed by comprehensively using the magnetic compaction belt, the conveyor belt and the magnet position adjustment device. According to the force analysis of the paper-plastic composite bag, a mathematical model of dynamic magnetic compression correction was established. Then, the finite element modeling of the magnetic compression correction device for paper-plastic composite bag was carried out. The boundary conditions and contact parameters were set according to the correction process of the paper-plastic composite bag, and the dynamic correction process was simulated by the explicit dynamics analysis method. Then, based on the simulation results, combined with BP (back propagation) neural network and GA (genetic algorithm) (referred to as BP-GA algorithm), a process parameter optimization model of the magnetic compression correction device for paper-plastic composite bag was established. Finally, the process parameters of the magnetic compression correction device for paper-plastic composite bag were optimized by the corresponding calculation programs. The results showed that the designed magnetic compression correction device for paper-plastic composite bag could realize the correction function, and could make the wrinkles of paper-plastic composite bags during the transmission meet design requirements; the optimal process parameters of the device during correction were as follows: the electromagnet magnetic force was 7 N, the gap between the left and right belt components was 476 mm, the dynamic friction coefficient between the belt components and the paper-plastic composite bag was 0.25, which was consistent with the optimization results based on the BP-GA algorithm. The research results can provide a reference for the further study of continuous magnetic correction of paper-plastic composite bags.

Aiming at the problems of high cost, large floor space and failure to meet the emission standards of the existing wet waste treatment device nearby, a new type of mechanical compressive wet waste treatment device is developed. Firstly, the functions and technical characteristics of the mechanical compressive wet waste treatment device were introduced. Then, the modular design of the mechanical compressive wet waste treatment device was carried out, which mainly included the lifting device, the conveyor belt sorting device, the crushing and dewatering device, the sewage treatment device and the briquetting device. Finally, the technical parameters of the mechanical compressive wet waste treatment device were designed and calculated, and its automatic control scheme was designed. The designed mechanical compressive wet waste treatment device integrated the traditional waste crusher and the press dehydrator to realize the efficient dehydration of the wet waste; through the treatment of the briquetting device, the compression of the waste residue was realized, which could effectively relieve the problems of tight capacity and secondary pollution in the waste transportation; by the treatment of the sewage treatment device, the recycling and reuse of sewage was realized. The mechanical compressive wet waste treatment device has the advantages of low cost, small volume, simple treatment process and less labor resource consumption. It is suitable for small and medium-sized waste collection stations that have implemented waste classification and collection, and has broad market prospects in the wet waste treatment industry.

In order to avoid the direct contact between garbage in the garbage can and human body, reduce the pollution of garbage to the environment, an electric heat sealing garbage can was designed based on the electric heat sealing technology. Taking MSP430 single chip microcomputer as the control core and adopting trapezoid screw transmission technology, the rotation of the stepping motor was converted into the linear motion of the garbage can pressing device; in addition, reasonable circuit design and double-layer electric heating wire structure are used in the pressing device, so as to seal plastic garbage bag with no gap and low noise; LCD12864 LCD (liquid crystal display) and voice module were selected to reflect the sealing process in real time using words and sounds. The sealing unit and electric heat sealing control unit of garbage can were designed, and the sealing experiment of plastic garbage bag was carried out. The experimental results showed that PE (polyethylene) garbage bag and Cr20Ni80 heating wire could be used to realize electric heat sealing quickly and accurately. The research results have important reference value for the green design and intelligent design of garbage can.