Quality Improvement of PDC Rock Bits

Ⅰ. Improvement of welding process of PDC rock bit

1. Selection of welding materials

According to the requirements of the working conditions on the performance of the weld, and on the basis of referring to the relevant standards, it is decided to use the flux-cored wire gas shielded welding.

Flux cored wire gas shielded welding is a high-efficiency welding method developed on the basis of high-efficiency automatic welding of solid wire. It has the following advantages:

(1) The welding process performance is good;

(2) The deposition speed is fast, the production efficiency is high, and continuous automatic and semi-automatic welding can be performed, which is 3-4 times that of electrode arc welding;

(3) The adjustment of the alloy system is convenient, especially for the welding of low-alloy and high-strength steel, which is incomparable with solid wire;

(4) Low energy consumption, which can save 20%-30% of the comprehensive welding cost.

2. Welding groove form and size

Ⅱ. Development of PDC rock bit bit girth welding machine

1. The composition of the circular seam welding machine

The welding machine consists of five parts: welding positioner, welding manipulator, pressing device, preheating device and complete set of CO2 device.

2. Working principle of circular seam welding machine

Put the upper joint of the drill bit on the chuck of the welding positioner, place the lower body of the drill bit on the upper joint, align the welding groove, and press it down by the pressing device.

The positioner turns the two weldments and the pressing device to the level.

Put the heating torch on the torch holder on the pressing device, move the torch holder so that the heating torch is aligned with the position of the welding groove, ignite the heating, and the torch preheats the weldment to reach the preheating level. After the hot temperature, stop the heating and remove the heated weldment.

The manipulator moves the CO2 welding torch to the welding groove position for welding.

After the welding is completed, the positioner stops rotating, the manipulator removes the CO2 welding, the positioner is turned up 90°, the weldment and the pressing device are in a vertical position, the pressing device is released, and the pdc bit is taken out.

Ⅲ. Improvement effect of PDC rock bit

By improving the welding process and equipment, good results have been achieved and the overall quality of the PDC rock bit has been greatly improved.

(1) The whole welding process is simple to operate, and the labor intensity of welding is improved.

(2) Using thick wire welding, the arc has strong penetrating power, fast welding speed, large melting depth, small melting pool, narrow heat affected zone, small deformation of the weldment after welding, strong rust resistance, and good crack resistance. 

(3) The circumferential seam welding machine can meet the welding of drill bits with a diameter of Ф60mm-Ф280mm and a welding groove thickness of 5-30mm. It can meet the needs of circumferential seam welding in the drill manufacturing industry. At the same time, it can be used for automatic welding of other circular objects of the same size.

The drill girth welding machine was put into full production and continuously improved. Continue to optimize the welding process, improve the automation level of welding equipment, comprehensively analyze the problems that arise, and comprehensively improve the welding quality of drill bits.