Research on the Preparation and Properties of the Vitrified Bond for Diamond Grinding Wheel to Grind Polycrystalline Diamond Compact
Post Date: 24 Nov 2010 Viewed: 528
This paper aimed at the resin bond diamond grinding wheel" disadvantage such as the lower grinding efficiency, the higher noise, the worse uniformity of the grinded Polycrystalline Diamond Compact(PDC) size, and integrated the characteristics of vitrified bond diamond grinding wheel , discussed the feasibility of vitrified bond diamond grinding wheel instead resin bond diamond grinding wheel to grind PDC. We researched the choice of diamond, the materials" choice of vitrified bond, the manufacturing process of vitrified bond and the experiment of using vitrified bond diamond grinding wheel to PDC . We have done some experiment and research work about this. Now it"s abstracted the following:The first is the stability of the diamond in high temperature .We find that when the temperature exceed 700 centigrade, the diamond begin to oxidize in the air, the degree of oxidization of the diamond is related to its quality and its grain size. The lower quality or the finer size the diamond is, the higher degree of oxidization. But when the vitrified diamond stone is buried into quartz sand ,In 750 centigrade, the damage to diamond is much smaller. Integrated the thermal stability of diamond and the characteristics of grinding PDC, we chose the II diamond to be the vitrified bond grinding wheel"s abrasive.The second we defined the fastness to fire of the vitrified bond and the sintering temperature based on diamond thermal stability .we also used the formation enthalpy of the oxide to analysis the chemical reaction situation between the oxide and the diamond at the sintering temperature, the theory of glass structure to define the prescription of the bond.The third is the manufacturing process of vitrified. In this paper the vitrified bond is made by smelting. We discussed that different smelting curve influenced on the property of the vitrified bond, we found only when all the steam of crystallization and the decomposition gas is got rid of at a lower temperature, the properties of the vitrified bond can be stabilized. We also examined the properties of the smelted vitrified bond. The result of the examination : the fastness to fire of the bond is 580-630 centigrade, the coefficient of thermal expansion about the bond is 7.2-8.0 10-6 -1. Theseproperties can meet the diamond"s sintering demand. The bending strength of the diamond stone which is made of this bond is very high(45-58Mpa).The forth is the application of vitrified bond, including the grinding wheel"s manufacturing process and the grinding experiment. We find the resin bond"s still binding strength to the abrasive is not much lower than the vitrified bond. But its lifetime in grinding PDC is much shorter. The main reason we thought is that during the grinding process, the instantaneous temperature in grinding area is very high(might be 500 ), then the resin can become soft and the binding strength between the resin and abrasive is very weak ,so the decrement of the resin bond grinding wheel is very fast. In the other hand to increase its lifetime the resin bond grinding wheel is made very dense, so the grinding force is very large and the damage to the grinder"s main shaft is very large, but for the vitrified bond grinding wheel, this circumstance doesn"t exist.Through the grinding experiment, we"ve optimized the prescription of the v-bond and grinding wheel. The advantage of using v-bond diamond grinding wheel to grind PDC is the higher grinding efficiency, the better uniformity of PDC size and grinding noise. But the grinding cost of using v-bond diamond grinding wheel is a bit higher than the resin bond one.Next we will do more research work in the bond prescription in order to decrease the coefficient of thermal expansion, enlarge the binding strength between the vitrified bond and abrasive and improve the lifetime of vitrified bond grinding wheel.