Brazing diamond wire saw manufacturing process

Abstract: Traditional diamond wire saws are used to fix a layer of diamond abrasive on the surface of fine wire by electrodepositing nickel or thermosetting resin for precise cutting of materials. Since the abrasive is only mechanically embedded in the plating layer or the resin bonding agent, the abrasive is easily peeled off, and the wire saw has a short life. In order to solve this problem, a diamond wire saw is made by using a gas-protective induction heating brazing process to improve the bonding strength of the diamond abrasive. The development of gas protection device and the research of brazing process were carried out. The brazed diamond wire saw was successfully produced and the brazing mechanism was discussed. Key words: diamond; wire saw; induction heating; brazing process Introduction Diamond wire saw is a layer of diamond abrasive fixed by electrodepositing nickel or thermosetting resin on the surface of thin metal wire, which can be used to precisely form cutting silicon wafer, stone and ceramic. Hard and brittle materials such as optical glass can also be applied to the cutting of metal materials such as aluminum alloy. The advantages are as follows: 1) narrow slitting and high yield; 2) smooth cutting process, cutting brittle material such as silicon crystal and ceramic without chipping; 3) low cutting temperature, no burn on the cutting surface; 4) cutting large workpiece 5) It is less polluting to the environment and usually uses water as the coolant. It is a promising cutting process. The main problem of the existing diamond wire saw: the abrasive is only mechanically embedded in the plating layer or the resin bonding agent, the bonding strength between the abrasive and the bonding agent is low, the abrasive is easy to fall off, and the bonding agent layer is also easy to fall off, the life of the wire saw short. In the past ten years, some scholars at home and abroad have begun to study the use of brazing technology to make single-layer super-hard abrasive tools. The starting point is the melting, wetting, diffusion, which occurs at the interface of abrasive, solder and substrate by high-temperature brazing. Compounding interactions (so-called chemical metallurgical effects) fundamentally improve the holding strength of the matrix and the solder alloy to the abrasive. Compared with traditional electrodeposited nickel or thermosetting resin diamond tools, brazed diamond tools have the following characteristics: 1) Chemical, metallurgical bonding between abrasives, brazing fillers and substrates can be achieved, thereby increasing bond strength and tool life. 2) The abrasive grain has a high exposure height, large chip space, is not easy to block, and the use of abrasive is more sufficient; 3) grinding force, power consumption and low grinding temperature; 4) environmentally friendly, in line with today's advocacy Green manufacturing trends. At present, the research of brazed diamond tools focuses on the development and processing performance of hollow drill, grinding wheel, saw blade and beading. The brazed diamond wire saw has not been involved yet, and the production of brazed diamond wire saw has its unique characteristics. This paper attempts to make diamond wire saws by UHF induction heating Ar gas protection brazing for the first time at home and abroad. It is expected that the work of this paper can help promote the practical research process of brazed diamond wire saws. Process test conditions Vacuum resistance furnace welding and gas protection induction heating welding are all feasible methods. Due to the slow heating rate of the vacuum resistance heating furnace, the long-time high-temperature heating adversely affects the microstructure of the substrate and the performance of the diamond abrasive grains, and in particular, the tensile strength and bending strength of the wire saw wire are significantly reduced. Therefore, an induction heating device is selected for brazing to make a diamond wire saw. Compared with brazing in vacuum resistance heating furnace, induction heating brazing has unique characteristics: fast heating speed, fast cooling speed, small influence on tensile strength of steel wire; brazing of super long wire saw (such as 100 km) . The high-frequency induction heating brazing system used is shown in Figure 1. The power is 50 kW and the frequency is 200-250 kHz. The system consists of an induction heating power supply and a gas protection device. In order to avoid thermal damage of the diamond abrasive during high temperature brazing, it must be brazed in a vacuum or a protective gas. The thermal damage of diamond is related to the atmosphere. The temperature at which diamond begins to graphitize in air is 800 °C. Under normal industrial protective atmosphere or vacuum, the temperature at which the diamond begins to thermally damage is 1 200 °C. According to the different shielding gas, it can be divided into reducing gas brazing and inert gas brazing. The reducing gas means hydrogen (H ₂ ), or a mixed gas of hydrogen and nitrogen (H ₂ , N ₂ ), or a mixed gas of hydrogen, nitrogen, carbon monoxide (H ₂ , N ₂ , CO), wherein hydrogen and carbon monoxide are Reduced gas. The inert gases are mainly argon (Ar) and helium (He). The device selects argon as the shielding gas. The self-developed gas protection device is shown in Figure 2. It consists of an induction coil, a gas protection chamber, two air inlets and two air outlets. Argon gas is introduced from the two air inlets into the protection chamber, and the air is removed from the two air outlets. The wire saw to be brazed enters from the lower air outlet, enters the induction coil for heating and brazing, and then exits from the upper air outlet. Continuous brazing of wire saws is possible.