# Sand Removal Mechanism of a High-Speed Roller Bit with Helical Sealing
## 3 Methods
### Experimental Procedure  
In the first test, the uniaxial test without pressure mainly verifies the feasibility of helical sealing and the effects of different helical structure parameters on the sand removal performance. The pumping weight measurement method was used to weigh the liquid entering the device and the liquid removed  
Figure 6: High-speed bearing testing machine. Figure 7: Drilling bit and fixture. from the device. The flow direction is shown in Figure 4. The roller (19) was connected with the motor (17) and the bearing (25) was stationary. As the motor (17) was stationary, the roller (19) did not rotate and the helical sealing (26) did not have a pumping function. The liquid was injected into the liquid container (3) with a mass of 5000 g, and the valve (4) was opened. Additionally, the liquid entered the working place of the helical sealing through two symmetrical holes along the axes of entrances A and B. The pumping function of the helical sealing (26) ring with high speed allowed liquid to flow into the active removal device. The liquid was removed through outlet (E) and along outlets (C) and (D). The liquid in the container (14) was weighed and the weight difference between the liquid entering and the liquid collected was calculated. The difference was the leakage of the helical sealing, and the sand removal performance of the helical sealing can be evaluated. As the motor (17) operates the roller (19) rotated with high speed, the roller (19) can drive the rotation of the helical sleeve (26) to realize the helical sealing (where helical sealing plays the role of pumping and removing sand). On the premise of the same volume of liquid being injected into the liquid container (3), the above test process without pumping action was repeated, and the difference in the pumping weight was recorded. The performance of helical sealing was evaluated by comparing the weight difference between the same volume of liquid entering and removed with the motor not working (i.e., the helical sealing ring has no pumping effect) and the motor working (i.e., the helical sealing ring can drive and remove sand). When the motor was not working, the weight difference was great because the screw cannot pump the sand. When the motor was working, the weight difference was small because of the pumping sand removal of helical sealing. The weight difference was thus inversely proportional to the performance of helical sand removal. The above results are used to evaluate the performance of helical sealing sand removal. As the roller rotates, the optimum rotational speed and helical structure parameters were obtained by measuring the pumping weight for different rotational speeds and helical structure parameters. By comparing the sealing weights, the pumping and sand removal effects of the helical sealing can be evaluated. A large weight difference suggests that the helical sealing does not have a sand removal effect whereas a small weight difference suggests that helical sealing has a sand removal effect. Meanwhile, this method can be used to test the sand removal performance of helical sealing with different helical structure parameters. The weight difference is inversely proportional to the sand removal performance of the helical sealing. The optimum rotational speed and helical structure parameters can thus be obtained. In the second test, the uniaxial test of the pressurized medium investigated whether there was liquid infiltration in the sealing chamber. The sealing performance was good if there was no liquid infiltration in the sealing chamber; otherwise, the sealing did not meet the requirements. This was the main criterion for evaluating the sealing performance of the helical sealing ring. In the third test, the axial load was 0.3 t while the radial load was 1 t (which was the maximum allowable output load in the high-speed bearing test).