Periphery Of Grinding Wheel Research Articles

Development of a Grinding Fluid Delivery Technique and Its Performance Evaluation

In grinding process, a stiff air layer is generated around the wheel due to rotation of porous grinding wheel at high speed. This stiff air layer restricts fluid to reach deep inside the grinding zone. Conventional method of fluid delivery system is not capable of penetrating this stiff air layer, and thus cannot control grinding temperature and thermal defects effectively. In this work, formation of stiff air layer has been studied experimentally by measuring the variation of air pressure around grinding wheel periphery at different conditions. A pneumatic barrier setup has been developed first time for restricting the stiff air layer around grinding wheel. It is found from analysis of variance (ANOVA) that both pneumatic barrier position and orientation have significant effects on suppressing air layer pressure around the grinding wheel. Using the pneumatic barrier, reduction of air pressure up to 53% has been observed experimentally. Hence, it reduces wastage of grinding fluid, leading to less environmental problem. Surface grinding experiments using the pneumatic barrier setup shows remarkable reduction in forces and surface roughness over flood cooling conditions expectedly due to better penetration of fluid in the grinding zone, showing its applicability.

A Quick-Test Method to Determine the Grinding Wheel Topography Based on Acoustic Emission

A quick-test method for the determination of the topographic characteristics of a CBN grinding wheel is developed based on acoustic emission technology. For implementing the strategy, an acoustic emission (AE) monitoring system was integrated into a 3 axis CNC grinding machine. A computer with specific software allows the signal acquisition and visualization of the AERMSsignals, which are originated through interferences between the grinding wheel and dressing tool in a range of a few micrometers. The acquired AERMSsignals from these interferences are used in order to establish an on-line map from the grinding wheel periphery, indicating the active cutting grains during the contact amid grinding wheel and dressing tool. The implementation of such activity supported by AE has led to satisfactory results regarding the required time to evaluate the strategy as well as the verified correlation with different grinding topographies caused by changes in the dressing parameters.

Improving grinding performance by controlling air flow around a grinding wheel

In grinding, high specific heat is generated, and hence, appropriate control of temperature through effective flow of grinding fluid is necessary to obtain a quality ground surface. It is known that in conventional fluid delivery method, most of fluid is wasted due to presence of a stiff air layer around the grinding wheel. This air layer is generated around the wheel due to the rotation of the porous grinding wheel at a high speed. To improve grinding performance, hence, penetration into this air layer is required. In this work, a pneumatic barrier set-up has been developed for controlling the stiff air layer around the grinding wheel. The formation of stiff air layer has been studied experimentally by measuring the variation of air pressure around grinding wheel periphery at different parametric conditions of pneumatic barrier. This pneumatic barrier tends to break the stiff air layer before the fluid flow area or grinding zone. A remarkable amount of reduction in pressure of the air layer is observed at the fluid flow zone. To observe beneficial effects of suppressing the air layer, grinding experiments are performed under dry, flood cooling and flood cooling with pneumatic barrier setup. Reduction of grinding forces and surface roughness are clearly observed with the use of pneumatic barrier setup, and hence, its applicability.

Coolant effect on grinding performance in high-speed deep grinding of 40Cr Steel

High-speed deep grinding (HSDG) technology was developed based on high-speed and creep-feed grinding techniques. What mainly distinguishes HSDG from creep-feed grinding is its employment of a significantly higher wheel speed. Because the higher wheel speed results in a decrease in the undeformed chip thickness, HSDG is thus capable of achieving high stock removal rates and producing a high surface quality throughout the workpiece. However, the increase in wheel speed leads to the formation of a strengthened air barrier around the grinding wheel periphery, which is a great obstacle to the impinging of coolant into the grinding zone. Additionally, the higher wheel speed will also generate greater grinding heat in the grinding zone, thus resulting in a higher temperature.'This increases the risk of thermal damage on the workpiece, such as burns and cracks, especially when grinding metals and alloys. In order to take advantage of the full potential of HSDG technology, effective cooling must be employed. Great research efforts have been directed toward investigating effective coolant supply technologies for the HSDG process. 71° Previous works focused on the development of coolant nozzles for high-speed grinding, which could block the air barrier formation and help smoothly guide the coolant entering the grinding zone. There are several drawbacks regarding these nozzles. First, a gap between the wheel and the air-wiper in the nozzle still exists, which affects the coolant supply when operating at an extremely high speed. Second, the air blocking alters the coolant flow direction, thus resulting in an increase of 30-50% in spindle power. Third, special grinding wheels are required if there is direct contact between the wheel and the air wiper. This article will report on the development of a closed coolant shoe, which can overcome the limitations of previous coolant nozzles, and the effect of the new nozzle on the grinding performance in HSDG of 40Cr steel.

研削砥石の研削性能に関する研究 (第2報)

The local grinding property of a grinding wheel periphery depends on the grade irregularity which is formed as results of ununiform mixed state of wheel materials, pressure gradient produced by pressworked process and temperature gradient produced by burning process. Hence, it is necessary to investigate the bad influence of grade irregularity in order to grind the workpiece with high geometrical accuracy. In this report, we express the irregularity of wheel. grade in the elastic modulus measured with ultrasonic pulse method which is non-destructive inspection, and examine the effects of the magnitude of grade irregularity and the distribution of elastic modulus of a wheel periphery on the cylindrical configuration of workpiece. Then the relationships between the grinding conditions and magnitude of wave on the workpiece surface are analyzed to make it clear that the limited revolution ratio of wheel to workpiece minimizes the bad influence of grade irregularity.

自励びびり振動の発生限界に関する研究

This paper deals with analysis of the transition phenomena changed from the stable to the unstable grinding. From the previous paper, the grinding system can be expressed by the model of the parametric vibration system, and so it is made the Mathieu's equation. The parametric factor on its equation, which is the "working state" of the grinding wheel periphery, is given the criterion of the stable grinding. The characteristic phenomenon, which is progressive increasing chatter-amplitude, can't be explained by the usual regenerative theory, but can be made clear by the above method. The experimental results obtained the approximate 40% agreement with the theoretical analysis. Futhermore, the principle of chatter prevention is considered by means of this method.

研削初期のびびり振動の発生原因と振動モデル

There are two categories of the self-excited chatter vibration in cylindrical grinding-wheel regenerative and work regenerative theories due to the waviness on periphery. In the wheel regenerative chatter phenomena not cooperating with any work regenerative chatter due to the geometrical interference between the workpiece and the wheel, any waviness on the wheel periphery can't be observed at the early grinding time. However, at that time the apparent chatter vibration can be observed. Such phenomena can't be explained by the regenerative chatter theory. For explaining the above phenomena, the "working states" of the grinding wheel periphery has been observed in detail. From the above observation it is proposed that the grinding system can be expressed by the model of the parametric vibration system.