Search

This paper proposes a capacitance resistance measurement method based on time constant. Using the charging and discharging characteristics of the resistance and capacitance measures the value of the resistance and capacitance through a semi potential rise and fall time measurement. Theoretical analysis of the relationship between the value of the resistance and capacitance and the measuring time, designing the fast second charging and discharging method meeting the initial condition of charge and discharge, improving the measurement speed, expanding the measurement range of the resistance and capacitance. Realizing the effective measurement of the resistance and capacitance by the FPGA control logic and timing method.

Residue of alloy anode generated in three-layer liquid electrolytic purifying method is refined, the state of iron in raw materials is analysed. The state (morphology) changes of iron refined by different refining agent are investigated. Results show: 40% of boron salts or phosphate as the main component of refining agent adding 15% NaCl、20% KCl、15% CaF2、5% NaF、5% cryolite, melting the residue of alloy anode at 1100°C and 1200°C respectively, the crystal could be incubated to grow up fully, it is benefit for collecting iron. When the soaking time is 150min, iron component in alloy is 4.8%,it reaches the standard taking back into the aluminum refining process.

The chatter between tool and workpiece has become a problem that urgently need to be solved in modern manufacturing system development.This paper analyzes the main factors in affecting the flutter when to turn ring groove of inner hole for large stainless steel thin-walled pieces. take normal direction of workpiece cutting surface as modeling direction, consider processing status of the large cylinder workpiece with large diameter, large height, small wall thickness and vertical large overhang. Based on vibration theory, establish a vibration dynamic mathematical model for large thin-walled parts in turning process, investigate the flutter in processing, provide a useful reference for solving the vibration problem of large cylinder parts in processing.

During precise hard cutting, back cutting depth and feed rate are relatively small. Study on the influence of PCBN (Polycrystalline Cubic Boron Nitride) cutting tools edge (chamfer edge or cutting edge radius) on cutting force is important. As the effect of cutting edge on mechanism of shear slip plane is very complicated, so to study the effect of consider cutting edge parameters and cutting parameters by genetic algorithm on cutting force, to build up cutting force model of precise hard cutting. It is feasible to predict cutting force by genetic algorithm with experiment.

Because the tube festivals surface is not round, uneven, so the cutting tool is under impact unceasingly in cutting process. Cutting tool is extremely easy to have fatigue failure, therefore it is very necessary to use finite element numerical analysis software ANSYS to carry on numerical simulation analysis for heavy lathe tool intensity static. The force of cutting tool and distributed rule of definite cutting tool internal stress strain could be precisely got by using FEM, thus the analysis results could improve cutting tool stress condition and the structural design provides the theory basis

In order to implement the measurement of two-dimensional small angles, a method of modulating optical-path differences through a wedge is put forward, based on Michelson interference principle. By promoting the wedge with a voice coil motor, optical path that pass through the wedge will be changed. Then the optical-path differences on fixed points of the receiving screen will be cycle changed. Then the interference fringes will be carried out on periodical motion. Utilizing voice coil motor and right angle flexible hinge moving cycle, the relationship between the driving voltage and the displacement of wedge also has been analyzed detailedly. The experiment results show that there is a good linearity while the driving voltage is in the range 3.2v-7.5v. Modulating optical-path in this linear range, precise measurement of two-dimensional angles can be realized.

Firstly, with studying three typical aspects as cutting force, cutting temperature and chip breaking behavior, contrast experiments of machinability were made on hydrogenated cylindrical shell materials (2.25Cr-1Mo-0.25V), 45 steel, and stainless steel (1Cr18Ni9Ti). The experiment results show that the depth of cut ap have a larger effect on the main cutting force FZ and the cutting temperature θ than the affection of the feedrate f, for that reason, in order to reduce the main cutting force FZ and the cutting temperature θ, large feedrate situation will be better for machining work of hydrogenated cylindrical shell materials. When cutting hydrogenated cylindrical shell materials , many difficult points appearance, such as large cutting force, high cutting temperature, serious chips winding, chips difficult to break etc, which has worse machinability even than stainless steel(1Cr18Ni9Ti).

In the cutting process, cutting force is one of the important physical parameters, which affects the generation of cutting heat, tool life and surface precision of workpiece directly. In this paper an orthogonal design of experiment and subsequent data is analyzed using high speed finish hard cutting GCr15 whose hardness is 65HRC. Cutting speed is 200-400m/min, to study the influence of cutting parameters on cutting force, cutting force empirical model has obtained from least square method.

PCBN cutting tool’s wear in high speed precision reaches tool wear criterion will cause cutting force and cutting temperature increase clearly, chip color change or melt. Even vibration in cutting will influence dimension accuracy and surface quality of workpiece. It is very useful to establish model by FEM simulation of tool wear predicted. The influence of tool wear in cutting conditions will assurance of machining quality and efficiency, decreasing rate of product cost. PCBN cutting tool’s wear is simulated by FEM software Deform 2D, rake face wear state can be analysed by the influence of tools geometric parameters and cutting parameters tool wear.

Based on experimental results, a predictive model with certain constraints of cutting parameters (feed rate and depth of cut) and nose radius for cutting forces is solved in precision turning 3J33 alloy. The proposed model is adequate with F-ratio test and multiple correlation coefficient of it. Regression analysis shows that depth of cut and feed rate influence the principal cutting force significantly. The goal of this study is to predict cutting forces under certain constraints of cutting parameters and nose radius.

A 3D model is established in this paper to simulate cutting process of PCBN tool cylindrical cutting hardened steel GCr15 using ABAQUS/Explicit. The model effectively overcomes serious element distortions and cell singularity in high strain domain caused by material large deformation by adopting shear failure criteria and element deletion criteria. In this study cutting force, cutting temperature, surface residual stress field as well as side flow are forecasted of hard cutting process with chamfering tool preparation. It shows that satisfactory results could be obtained by FEM. The simulation results provide theoretical basis for studying hard cutting mechanism and selecting the best cutting condition in practical.