Tangential Grinding Research Articles

Analysis of reverse heat transfer for conventional and optimized lubri-cooling methods during tangential surface grinding of ABNT 1020 steel

A numerical thermal model was developed to evaluate the heat flux which is conducted to a rectangular workpiece of steel plate ABNT 1020, thus making it possible to compute the maximum temperature in the grinding surface, taking into account the rectangular distribution of heat flux, the thermal properties of the grinding wheel conventional Al2O3, the piece to be machined and the lubri-refrigerating fluid. The finite volume method was employed for the discretization of the direct thermal problem from the heat diffusion equation associated with the two-dimensional problem of heat conduction in transient regime. The inverse thermal problem was solved by the Golden Section technique. The thermal flux, when compared to the conventional technique of method of application fluid, was reduced by 84.0% in the practices performed with cutting depth of 30µm, at 74.0% in practices with cutting depth of 45µm and 61.2% in the aggressive practices of 60µm, thus demonstrating the applicability of the optimized method for fluid application.

Dental Grinding of Lithium Disilicate Ceramic Prostheses Using High-Speed Rotary Cutting Instruments in <i>In Vitro</i> Oral Adjusting

Oral adjusting of ceramic prostheses involving abrasive machining using dental high-speed rotary cutting instruments is a central process in restorative dentistry, because this process affects not only restorative quality but also patients’ comfort. However, the dental grinding process, especially dental grinding of high-strength ceramic prostheses, is less understood in clinical dentistry. This paper presents dental grinding of an innovative high-strength lithium disilicate ceramic in in vitro oral adjusting regime using a dental high-speed electric handpiece and diamond burs. The dental abrasive machining characteristics were quantitatively evaluated in terms of normal and tangential forces, force ratio, and specific grinding energy as functions of clinically relevant dental grinding variables including depth of cut and feed rate and feed direction of burs. The results showed that the dental tangential and normal forces and specific grinding energy exhibited significant dependences on depth of cut, feed rate and direction of burs, but revealed significantly small scales compared to engineering machining regime. Clinical implication was given that down grinding undoubtedly reduced the abrasive adjusting forces to relieve patients’ discomfort in oral regime. Moreover, dentists must be cautious in dental abrasive adjusting of the lithium disilicate ceramic prostheses at or beyond the specific material removal rate of 2.4 mm3/min due to significantly large forces and vibrations.

Grinding performance in crankshaft pin journal path-controlled grinding of 40Cr using CBN wheel

In path-controlled grinding, unlike the cylindrical plunge grinding, the contour of the pin journal is achieved with the coupling actions both of the eccentric rotation of the pin and the grinding wheel linear movement. Since the circumferential feed rate varies periodically in path controlled grinding of crankshaft pin, the tangential and normal grinding force keep unsteady during the whole process. Therefore, it is necessary to acquire thorough understanding on the grinding characteristic in terms of grinding force, grinding force ratio, and specific grinding energy during path-controlled grinding. The rotational measurement method was used for achieving the grinding force information during grinding. A series of experiments were performed to investigate the machinability in crankshaft pin journal path-controlled grinding of 40Cr using vitrified bonded cubic boron nitride (CBN) abrasive. The effects of grinding parameters on grinding force are illustrated. Experimental results show that the grinding force ratio rises with increasing workpiece peripheral speed. The specific grinding energy is found to decline with increasing material removal rate. It is beneficial that the undeformed chip thickness should be designed largely for reducing the energy consumption.

Research on Stability Prediction of the Crankshaft CNC Tangential Point Tracing Grinding

As the key part of internal combustion engines, crankshaft with high efficiency and accuracy processing has always been the target of the engine manufacturer’s pursuit. Grinding is used to obtain the ultimate dimensional accuracy and surface finish in the crankshaft machining. Grinding of the main journals and the pin journals can be accomplished in a single clamping operation by CNC Tangential Point Tracing grinding technology. However, the chatter in the grinding process is harmful to the precision and surface quality. In this paper, stability lobe diagram is developed to predict the grinding chatter. First the dynamic model of Tangential Point Tracing grinding system is established. Then the limit formula of the critical grinding depth is calculated and the stability lobe diagram of the grinding system is presented. Finally, the validation experiments are carried out on the crankshaft grinding machine and the results are consistent with the calculation.

Research on Automatic Alignment System for the Crankshaft of Marine Diesel Engine in Tangential Point Tracing Grinding

Research on Automatic Alignment System for the Crankshaft of Marine Diesel Engine in Tangential Point Tracing Grinding

Grinding Force, Specific Energy and Material Removal Mechanism in Grinding of HVOF-Sprayed WC–Co–Cr Coating

The present study applies the machining approach and other analysis techniques to investigate the material removal behavior during surface grinding of high-velocity oxy-fuel (HVOF) thermally sprayed WC–10Co–4Cr coating using a resin-bonded diamond wheel. The basic grinding factors such as force ratio, specific material removal rate, maximum undeformed chip thickness, and specific grinding energy have been investigated and discussed. The mathematical models containing linear terms and interactions of the first-order have been used to investigate the effect of the grinding parameters on the grinding force. The results have shown that both tangential and normal grinding forces depend not only on the depth of cut, feed rate, and cutting speed, but also on the depth of cut and feed rate interaction. Scanning electron microscopy (SEM) examination of the ground surface has revealed that the mechanism of material removal presents both brittle fracture and ductile flow modes. Considering the effect of the process parameters on the grinding mechanism, it has been inferred that the portion of the material removal mechanism associated with brittle fracture or ductile flow can be different according to the grinding parameters variations. Also, the SEM photographs have shown that large amounts of energy have been expended by plastic deformation due to plowing.

A New Method of Track Approaching Based on Sectioned Polynomial for Crankshaft Tangential Point Tracing Grinding

The motion path of grinding carriage about workpiece rotation angle in crankshaft tangential point tracing grinding is a complex curve. For such complicated movement curve, it’s necessary to find a proper path approximation method to meet the high requirement of speed and precision of path interpolation. Sectioned polynomial is effective to approach to complicated path which ensures the approximation precision with low-order polynomial. This paper presents a dynamic sectioned cubic polynomial approximation method based on approximation error which ensures the continuity of the neighboring sectioned cubic polynomial curves at their boundary points to realize the stable tangential point tracing grinding of crankshaft at high speed.