Data Measuring System for Torque Measurement on Running Shafts Based on a Non-Contact Torsional Dynamometer

The need for power measurement transmitted by the running shaft has led to the need for using devices for measuring torque on the shaft. Of particular importance is the power measurement on high-speed machines, wherein some cases conventional measurement systems are either unsuitable or have low accuracy. Currently, data measuring systems are widely used in the researches of turbomachines. They allow to receive, process, transmit, store and display measurement data. Their application is relevant in relation to the priority of experimental study and subsequent modeling of characteristics and performance factors of expansion machines. The purpose of this research is a design and generation of the data measuring system for measuring torque on the running shaft of vortex expansion machines using a non-contact torsional dynamometer (strain-gauge clutch). The research has considered the results of the development of data measuring system, performed a theoretical analysis and presented the results of the practical application of the non-contact strain-gauge dynamometer designed for torque measurement on the shaft of low-power expansion machines when operating under bench test conditions. Has dealt with the problems of development, calibration. Keywords: data measuring system, torque, coupling, resistive-strain sensor, vortex expansion machine.

Validity and reliability of strain gauge measurement of volitional quadriceps force in patients with COPD

This study investigated the validity and reliability of fixed strain gauge measurements of isometric quadriceps force in patients with chronic obstructive pulmonary disease (COPD). A total cohort of 138 patients with COPD were assessed. To determine validity, maximal volitional quadriceps force was evaluated during isometric maximal voluntary contraction (MVC) manoeuvre via a fixed strain gauge dynamometer and compared to (a) potentiated non-volitional quadriceps force obtained via magnetic stimulation of the femoral nerve (twitch (Tw); n = 92) and (b) volitional computerized dynamometry (Biodex; n = 46) and analysed via correlation coefficients. Test–retest and absolute reliability were determined via calculations of intra-class correlation coefficients (ICCs), smallest real differences (SRDs) and standard errors of measurement (SEMs). For this, MVC recordings in each device were performed across two test sessions separated by a period of 7 days ( n = 46). Strain gauge measures of MVC demonstrated very large correlation with Tw and Biodex results ( r = 0.86 and 0.88, respectively, both p < 0.0001). ICC, SEM and SRD were numerically comparable between strain gauge and Biodex devices (ICC = 0.96 vs. 0.93; SEM = 8.50 vs. 10.54 N·m and SRD = 23.59 vs. 29.22 N·m, respectively). The results support that strain gauge measures of quadriceps force are valid and reliable in patients with COPD.

Applying an Improving Measurement of Cutting Force to Study Machinability of Gray Cast Iron

In order to study the machinability of gray cast iron, the cutting force must be precision measure. An improving measurement based on strain gauge dynamometer has been proposed in this paper, the measurement changed the traditional calibration method of strain gauge dynamometer. A set of new calibration device have been designed. Use the device, the process of calibration could be made after the strain-gauge dynamometer for cutting force measuring fixed on lathe, in this way, the states of calibration and measuring in experiment achieved same, and the error of measuring which had been begot by the differ states of calibration and measuring could be eliminated. The results of experiment show that the method presented in this paper achieved high precision and low cost cutting force measuring, and the results of cutting force measuring could be used for estimating machinability of gray cast iron.

The Effect of Tool Edge Preparation of Indexable Carbide Insert

The paper focused on the effect of tool edge preparation of indexable carbide insert on cutting temperature, force and tool wear. The initial wear experiments were carried out to measure flank wear and two criteria to evaluate the effect of tool edge preparation were proposed. The cutting temperature measurement utilized tool-work thermocouple and revealed that the cutting temperature of honed insert was lower. The cutting force measurement with a strain gauge dynamometer showed that tangential cutting force Fz, feed force Fx would be increased and radius force Fy would be decreased after tool edge preparation.

Force and Temperature in Dry Cutting of Hardened W18Cr4V with PCBN

An experimental study was carried out to investigate the effects of cutting parameters on cutting force and temperature in cutting of hardened W18Cr4V with PCBN cutter. Three components of cutting force were recorded by a strain-gauge dynamometer and the cutting temperature was measured by a nature thermocouple of tool-workpiece. The cutting parameters were arranged by orthogonal method. It is shown that the cutting temperature increased with each of the three cutting parameters and the main effecting factor is feeding speed. The three components of cutting force increased greatly with an increase in feeding speed and cutting depth. But the forces decreased a little as cutting speed increased. The main and axial cutting forces depend mainly on cutting depth whereas the radius force is mainly influenced by feeding speed.