The button bit has high rock breaking efficiency, can effectively eliminate the blind area of rock breaking at the bottom of the rock formation, avoid repeated crushing of cuttings, and has no limit on the diameter of the drill bit, which makes it play an essential role in the field of rock drilling engineering, and it has become an indispensable tool. Similarly, these advantages of the button bit also require some requirements in production, so what are these production requirements?
The production requirements of the button bit are in the selection of materials, equipment, processing accuracy, and production technology.
Material selection
When selecting materials, it should be based on the power of the small rock drill, rock conditions, and operating characteristics. That is to say, the use of steel that does not exceed the range will cause a waste of materials, and the use of materials that are too low will cause the drill bit to be unusable. The aspects that can be considered for material selection are as follows.
1. In the state of heat treatment, the material has good plasticity, toughness, and hardness.
2. Good high-temperature strength and thermal stability.
3. Good fatigue strength and low-notch sensitivity.
4. Good cold working performance.
In the case of meeting the above conditions, it is also necessary to choose materials reasonably according to the usage habits and conditions of the mine.
The processing technology of skirt body of rock drill bit
The processing technology of the skirt body of the rock drill bit mainly includes direct machining of bars, cold extrusion, hot extrusion, hot forging process, and warm extrusion. No matter which processing technology is used, the enterprise should strictly control the quality according to its own production equipment and production technology to produce qualified products.
Direct machining of bars
The utilization rate of raw materials in this process is low, and the production cost is relatively high. In the early days, the use of this process more, but with the increased automation of processing equipment, the reduction of labor, especially in the machining, the surface raw material defects, scratches, folding, micro-cracking, etc. to remove, there is no excessive changes to the metallurgical organization of the raw material, eliminate processing stress, direct the corresponding heat treatment can be.
Cold extrusion
The process of plastically deforming the raw material in the mold cavity at room temperature to make the skirt’s body. This process has strict requirements on the mold, equipment tonnage, extrusion pretreatment process, material, deformation amount, and deformation speed.
Hot extrusion and hot forging process
This process requires high requirements for undercutting size, temperature, and protection of the skirt body blank. In the process of undercutting, the problems that are easy to occur include miter cut, length of undercutting, end burr and interlayer, end cracks, etc. These defects directly affect product quality.
Warm extrusion
Compared with other methods, warm extrusion can improve the utilization rate of the metal material of the skirt body, such extrusion, extrusion without flying edge, molding, labor productivity increased significantly, extrusion quality than the general die forging workpiece by more than 20%, the economic benefits are also increased a lot.
Heat treatment
Steel grades to achieve the desired mechanical properties, heat treatment is the most critical part of the process. Not only to achieve the required hardness but also to obtain a well-organized metallurgical organization under the second hardness, ensuring sufficient toughness and strength, while reducing tempering brittleness. Although the selection of prepared heat treatment and final heat treatment is different according to the material used for the drill bit and the skirt body forming process, the same thing is that during the heat treatment process, deformation, oxidation, and decarburization must be well controlled. Atmosphere protection or quenching in a vacuum furnace is required.
Inlaid carbide
To guarantee the accuracy of the rock drill bit, it is necessary to pay attention to the precision of the hole affected by factors such as the rigidity of the machining center and the wear of the drill bit, and the size of the ovalness and inverted taper of the carbide inlay hole is controlled within a limited range. According to the size of the inlay hole, a reasonable choice of the size of the interference amount. If the interference is too little, the solid tooth force is not enough, and when the drill bit is heated, the expansion coefficient of the skirt body and carbide is different, and the pressure is reduced, easy to cause the carbide button to fall off. If the amount is too large, the pressure of the matrix hole wall is too high, which will cause the fatigue fracture of the drill bit.
To sum up, to ensure the long-term stability of product quality and maximize the economy, the production enterprise should rationalize the control of the production process, refine the production technology and management, communicate and cooperate with customers, and rationally select materials, molding, machining, heat treatment, button placement, selection of button shape, and inserts are all important.
