Publish Time: 2021-10-28 Origin: Site
The tricone drill bit is integrated, the whole bit has no moving parts, the structure is relatively simple, with high strength, high wear resistance, and impact resistance is one of the worlds in the 1980s three new drilling technology. It has advantages of fast speed, more footage, long service life. So how do you produce a bit that combines so many advantages?
Here is the content list:
The rolling process used to produce tricone bits
Principle of the tricone drill bit production technology
The rolling process is widely used in forming tricone drill bits in China. The biggest advantage of the process is high production efficiency, which can make full use of raw materials; The inner structure of the drill body has fiber continuity, fine grain, uniform distribution of carbide, and high red hardness. But the rolling process also has obvious defects, that is, the drill body is easy to crack. Under normal circumstances, the bit cracking rate is 5% ~ 10%, sometimes as high as 20% ~ 40%, every year only because of the tricone drill bit cracking will cause the enterprise to lose hundreds of thousands of yuan.
Many factors are leading to the tricone drill bit cracking, and different methods can be adopted to reduce the bit cracking rate according to different causes. But the results of the existing methods are not ideal, can not fundamentally solve the problem of cracking. It is found that more than 98% of cracks occur at the intersection of the edge belt and edge groove. It can be seen that the crack generation is directly related to the blade belt formation. The common rolling process is to roll the edge groove, edge back, and edge belt of the drill bit simultaneously on the four-high rolling mill, that is, the rolling groove and the rolling back are synchronized.
In the process of rolling groove and grinding back, the original four-high mill can still be used, but the sectional shape of the two-blade back fan plate is changed, that is, there is no blade with groove. At this time, the function of the two-blade back fan plates is only to fix the shape of the tricone bit and adjust the charge of the blade back. Four high mill passes of the two rolling processes are shown in the figure below. It can be seen from the figure that when the groove rolling and back grinding process is adopted, the crack at the edge belt is avoided because there is no groove in the fan plate on the edge back and the shape of the tci tricone bit is simple.
The causes of crack are as follows: when rolling groove and rolling back, the width and depth of the groove on the blade back fan plate are also different because of the different sizes of the bit edge belt, usually, the width is 0.45 ~ 0.95mm and the depth is 0.55 ~ 1.15mm. During hot rolling, the drill piece is heated to a near melting state under the action of the sector plate rolling, flowing and extending along the mill pass, and the metal flowing into the groove of the edge belt forms the bit edge belt. But the narrow groove of the blade makes it difficult for the metal to flow smoothly, so the defect of the blade is easy to occur. Especially when the blank body is cooling, the narrow and high edge belt is at the edge of the blank body, which is the fastest cooling speed and easy to produce stress concentration. Due to the influence of material, heating temperature, time, and speed, the machining accuracy of sector plate, it is easy to produce cracks in the edge zone. When the groove rolling and back grinding process is adopted, the mill pass is simple, the structure is reasonable, and the metal flow characteristics are met, so the above phenomenon can be avoided.
Hejian Hengji Bit Manufacture Co., Ltd. strictly implements the production standard of tricone bit and rotary tricone rock drill bit and has conducted a large number of tests before production and sales. If you are employed in the field of drilling and exploration, you can consider using our products for work.