Effect of offset on the blade stress in tube roll-cutting process
The main objective of this study is to obtain the reasonable range of offset in tube roll-cutting process by analyzing the effect of the process kinematics. For this aim, the roll-cutting processes are simulated. Due to the existence of the offset, the relative feed speed of blade is not constant. In this paper, the relationship between the radial feed speed shock of a blade relative to the tube and the offset is introduced. The effects of offset on the roll-cutting force and the blade stress have been analyzed. Regarding the stress of the blade, the offset should be less than 0.15mm for Φ76×3.5mm tube with the blade radial displacement per cycle as 1.0 mm.
Simulation Based Process Parameters Study of the Tube Roll-cutting
In the large-diameter tube product line, the tube roll-cutting induces the tube shrinkage. The dashing blade is vulnerable part in the cutting machine. To decrease the tube shrinkage and increase the blade working life, the cutting processes with various process parameters are simulated by using the FEM. This paper is concerned with the quantitative effect of process parameters on the tube rollcutting. The considered parameters are the initial feed speed and the maximum cutting force. A comparison between the numerical and experimental results proves the validity of simulation. The relationship between the tube shrinkage and the process parameters is obtained by studying the cut dimension. The result of the stress analysis shows the influence of process parameters on the stress value. The appropriate process parameters are recommended through comparison among the simulated results for cutting Φ76×3.5mm tube.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.