Fri, 22 Jun 2018 01:35:48 +0000
Technology for brazing diamond tools
1 metal binder diamond tool
According to different production methods, metal binder diamond tools can be divided into the following three types: powder metallurgy hot-pressing sintered diamond tools, electroplating diamond tools and brazing diamond tools.
1. Powder metallurgy hot-pressing sintered diamond tool
Powder metallurgy hot-pressing sintering diamond tools based on diamond cutting grinding materials, with metal powder as binder, by using the method of powder metallurgy, after mixing, granulation, pressure molding, sintering, and the necessary late finishing processing and become a kind of diamond tools products.
The products have been serialized and standardized, the varieties and specifications are complete, the product quality is stable, some products have certain competitiveness in the international market. Powder metallurgy hot-pressing sintering diamond tools are of various kinds of diamond products in the first category, is also the most varieties and dosage the biggest, the most useful category, its product sales accounted for more than 80% of the metal bond diamond tools.
While using this method to make diamond tools has been widely applied in various fields, and achieved remarkable economic benefits, but its consolidation technology of diamond grits itself always there is a serious shortage, the effective utilization rate of diamond in about 10%, caused the waste of resources of diamond grits. Mainly displays in the diamond grits is basically mechanical package with metal bond exists in the form of, the holding of the metal bond of diamond grits ability is not strong, the diamond tool in use process for the normal wear and tear, fall off, the out of the diamond is more, the diamond actual utilization rate is low, the diamond raw material waste.
The expert inside course of study for many years In order to improve the metal bond of diamond hold the ability to do a lot of work, In addition to through the study of the surface modification of diamond (surface metallization and surface morphology change, etc.) to enhance metal bond of diamond grits holding force has a certain effect, by directly add just the right amount of Ti In metal bond (Ti), Cr (Cr), In (indium), Zr (Zr), and other active element to strengthen the metal bond are no big breakthrough. In academic circles is generally believed that the enhancement mechanism of metal bond is through on the diamond surface with a layer of metal carbide formed between binder, by carbide as a transition layer, improve the bond of diamond surface wetting ability and the capillary action ability, to achieve the effect of chemical metallurgical bonding.
And actually in the process of hot-pressing sintering, in order to protect the graphitization of diamond grits, affect the use of the diamond quality and its sintering temperature melting temperature of these active elements, cannot form carbides, lead to less than the theoretical ideal effect on active element. The diamond abrasive particles had to be mechanically clamped in the metal binder without the so-called chemical metallurgical reaction. Therefore, this kind of tool only relies on the form of mechanical package to fix the diamond abrasive, and the control force of diamond is limited in the use process.
Watch a lot of powder metallurgy hot-pressing sintering diamond tools usage, found that the crumbs diamond grits of the space is formed in the operation process, is to rely on scraps of grinding and processing materials, diamond grits let chip space is a process from scratch, the effective use of time, so the diamond grits which let the average of the chip space is very small, so in the process of using attle jam makes processing materials and the phenomenon of burn cut workpiece is frequent.
1. 2. Diamond plating tools
Electroplating diamond tool is a kind of product that by electroplating, through the process of metal electrodeposition, a layer of diamond is firmly embedded in the metal matrix. The products have the characteristics of high efficiency, high grinding accuracy, the main products is given priority to with forming grinding and precision machining tools, products are widely used in geological exploration, stone material, machinery, automotive and defense industry and other fields.
Although the method of production of all kinds of diamond tool is widely used in certain industries, and achieved a certain economic benefits, but consolidation technology of diamond grits itself there are serious shortage, the effective utilization rate of diamond at about 20%. The main performance is that the metal binder has not strong control ability to diamond abrasive particles. Diamond abrasive particles are only mechanically embedded in the coated metal.
Plating, Ni Ni, Co or Ni – Co – Mn and other metal ions in the cathode of diamond and matrix surface precipitation, into, under, under a plating deposit in turn, so after deposit to a certain thickness, semi-finished products from the extracted solution for sand, thickening and a subsequent processing process, end up with the electroplated diamond tools. During the whole process, no chemical metallurgical reaction took place. So, such tools is only fixed on mechanical package with diamond abrasive, in use process of force is limited by the holding of the diamond, plating once wear to abrasive half height, the diamond grits can fall off naturally.
Observation found that a large number of electroplated diamond tools usage, not peeling off about two-thirds of diamond grits height is deposit in plating metal layer, so the crumbs diamond grits of the space is basically fixed, and is relatively small, it is still in use process will appear material attle jams and burn cut workpieces.
1. Diamond brazing tool
The brazing diamond tool is a kind of tool product which can weld a layer of diamond firmly on the metal matrix through the melting process of metal solder by brazing. The products have higher efficiency and single particle diamond the characteristics of long service life, high grinding accuracy, the main products cover all thick and coarse granularity of the electroplated diamond tools and parts of hot pressing diamond tools.
In order to avoid the traditional manufacturing method of holding force, low chip capacity space and exposed such problems as high and low loss, and greater use of the advantages of monolayer diamond tools, and began in 2000, the brazing technology is applied to the diamond tool manufacturing and get rapid development. As a new diamond tool manufacturing method, brazing technology has attracted wide attention at home and abroad. The brazing method is different from other welding methods. In the brazing process, the melting temperature of the filler metal is lower than the melting temperature of the base metal, and the brazing temperature is smaller than the solid phase line of the base metal and higher than the liquid phase line of the filler metal. For diamond, it requires that the brazing temperature is less than the graphitization transition temperature of diamond. When soldering, solder on the diamond surface wetting, capillary effect, filling, spreading, tightly wrapped diamond grits, at the same time between diamond and solder alloy in the form of carbides formed chemical metallurgical combination. To brazing diamond tools of legal system, the bonding strength of diamond grits and the blade height is higher, the edge sharpness and cutting performance improved, fixed and let chip space is larger, high efficiency grinding is especially suitable for high speed machining, hard material processing and precision machining. In recent years, the high temperature brazing single layer diamond tool has become a hot spot in the research and development of colleges and universities and manufacturers at home and abroad.