Enhanced grinding performance by means of patterned grinding wheels

In this paper, a new and innovative method for the patterning of grinding wheels is presented. The patterns are machined with a patterning tool by using fly-cutting kinematics. By changing the patterning process parameters, different pattern sizes and densities can be machined in a flexible way. Surface and cylindrical grinding experiments show that grinding with patterned grinding wheels can significantly reduce process forces, grinding burn, and grinding power. The surface roughness increases because less active cutting edges remain when grinding with patterned wheels. But especially for roughing processes, the results show great potential for increasing the overall grinding performance. The final publication is available at Springer via http://dx.doi.org/10.1007/s00170-014-6579-8.DFGFAPES

An experimental investigation into resonance dry grinding of hardened steel and nickel alloys with element of MQL

Current policies on environmental issues put extra pressures on manufacturing processes to be resource efficient and eco-friendly. However, in grinding processes, large amounts of cutting fluids are used. These fluids are not environmental friendly thus require proper management before disposal with associated cost. Hence, this work sets to explore low-frequency vibration in grinding in order to improve coolant application in conventional grinding at the first stage with the aim to introduce this into high efficiency deep grinding (HEDG) at latter stage. An attempt is made to grind nickel alloys with minimum quantity lubricant (MQL) as oppose to flood cooling. To achieve this with minimum alterations to the machine tool, a piezo-driven workpiece holder was developed for surface grinding. This simple innovative workpiece holder allowed oscillating during actual grinding process. However, this paper presents the results of low-frequency oscillatory grinding in dry and near-dry conditions. The response of the machine tool spindle unit is presented alongside with the workpiece holder response. In this investigation, hardened steels and nickel alloys were ground with vibration assistance. The grinding forces are illustrated together with the surface finish. The wheel performance is given in terms of grinding ratio

Estudo experimental do uso de rebolos convencionais na usinagem do aço VP-50 utilizado na retificação cilíndrica, por meio de diferentes métodos de lubrirrefrigeração

A retificação é um processo de usinagem preciso, sendo uma das etapas mais caras na fabricação dos moldes para injeção de termoplásticos. Na retificação o rebolo é a ferramenta abrasiva responsável pela retirada do material. O número de tipos de abrasivos e granulometrias disponíveis são bastante grandes e junto com a quantidade de ligas possíveis, estruturas e durezas, além dos formatos, fazem com que se chegue a um número enorme de produtos. O conhecimento das suas características técnicas, vantagens, defeitos e condições de trabalho são fundamentais para os engenheiros de produto, de processos e, naturalmente, para os gerentes de área industrial, identificarem qual o rebolo mais indicado para realização do processo de retificação. Dentre os aços utilizados na fabricação de moldes para injeção de termoplásticos destaca-se o aço VP-50, o qual foi o aço usado neste experimento, sendo usinado pelo processo de retificação cilíndrica. No processo de retificação, também foi adotado para fins de experimento dois métodos de lubrirrefrigeração, sendo eles o método convencional com lubrirrefrigeração abundante e o MQL que é a técnica com mínima quantidade de lubrirrefrigeração. O objetivo deste trabalho foi analisar de forma comparativa o desempenho de corte executado com três tipos de rebolos convencionais: rebolo de óxido de alumínio branco, rebolo de carbureto de silício verde e rebolo de carbureto de silício preto com óxido de alumínio branco. Os resultados foram analisados e comparados pelas variáveis de saída dos três tipos de rebolos, tipo de refrigeração e espessura equivalente de corte

Detection of grinding temperatures using laser irradiation and acoustic emission sensing technique

This paper presents a new method for the detection of grinding thermal behaviours using a laser irradiation technique. Laser irradiation was initially undertaken in the Lumonics JK704 Nd: YAG laser machine under mimic grinding conditions. Temperature elevation was controlled using laser irradiation by varying the laser energy and laser irradiation time. The signatures of acoustic emission (AE) were recorded as pure thermally induced AE signals. A series of grinding experiments were conducted separately to identify different AE sources during grinding. An artificial neural network (ANN) had been trained to distinguish high and low temperatures using laser thermal AE data. This trained ANN was then used to classify burn and no burn in the grinding zone. The classification accuracy achieved 71% when grinding Inconel718 materials. The novelty of this work is reflected in that the laser irradiation induced thermal AE signals can represent grinding thermal behaviour and can be used for grinding burn detection