Fabrication And Performance Evaluation Of The Diamond Grinding Tools By High-frequency Induction Brazing Technology

The single-layer brazing diamond tools with high protrusion and high-strength bonding between diamond grains and matrix have drawn a lot of researchers' interests. Many new types of brazing diamond tools, such as grinding wheels, beads, core drills have been manufactured. And the fabricating methods of the single-layer brazing diamond tools are multifarious. Some of these tools are manufactured with high melting point and foliated brazing alloy, but others with low melting point and powdered brazing alloy. And their heating means are different, such as furnace brazing, induction brazing and laser brazing. In this thesis, Nie base powdered brazing alloy with high melting point and HF induction heating method are chosen to manufacture diamond grinding tools. HF induction heating has some advantages of high heating temperature, non-intact heating, automatic control of the heating temperature and local heating, nearly pollution-free to the environment and so on.Presently, the studies related to single-layer brazing diamond grinding tools mainly focus on the brazing process. Few works have been done to the evaluation of the brazing grinding tools qualities, specially the influence of each parameter of brazing process to the brazing tools qualities. As to the evaluation to the machining performance, more attentions have been paid on the wearability and removal rate of the brazing grinding tools. Relatively few researches are concerned with the tracing detection of grinding process and grinding mechanism. Aiming at the optimization of brazing parameters, the relationship between the brazing parameters, the vacuum degree, temperature and holding time, are discussed in this thesis. Meanwhile, a shearing experiment is conducted and the shearing forces of the test samples under different brazing parameters are measured to further optimize the brazing process parameters. A grinding experiment is carried out with the brazing diamond grinding tool. The grinding force is measured and the worn pattern of diamond grits are observed in the whole grinding process which have some kinds of significance to the optimization of high-frequency brazing process. The main work achievements and results of this thesis can be summarized as follows:1. The bonding between the diamond grits and mental matrix is successfully realized under different brazing parameters with the high-frequency induction brazing technology. The influence of brazing time to the tool surface quality is analyzed by the observation of the microshape of the brazing tools with the Hirox KH-1000 optical microscope attached to a digital video system.2. Aiming at the mismatching between the matrix and induction coils, the uniformly heating of the matrix is realized by changing the shape of matrix, heating manner andheating routes under the premise of not affecting the performance of brazing tools and not changing the shape of induction coils.3. Two evaluation methods to the brazing tools are compared. The shearing force of single diamond grit manufactured under different brazing conditions and brazing parameters are measured, with which the relationship between the brazing parameter and the shearing strength are evaluated. The experiment results indicate that all three parameters have influence to the shearing strength of test samples. The strength of brazing grinding tools are almost decided by the strength of diamond abrasive itself. The main failure way of brazing tool is the fracture of diamond abrasive. Therefore, not all grades of diamond abrasive are fit for the manufacture of brazing diamond grinding tools.4. A monolayer brazing diamond wheel is fabricated by high-frequency induction. A grinding experiment is conducted to measure the grinding forces under different grinding parameters. The characteristic of brazing diamond wheel in the process of grinding are studied. The experiment results show that both normal forces and tangential forces linearly increase with the grinding depth, but decrease with the line speeds of brazing tools. With the further incre...