Do You Know the Four Drilling Methods and 15 Operating Skills of Rotary Drilling Rigs?

Rotary drilling rigs can be divided into four drilling methods according to geological conditions: cutting, crushing, turning, and grinding.

1. Cutting type:

Cutting drilling uses bucket teeth, double-bottom sand buckets, and friction drill rods to drill relatively stable strata with low resistance. Generally, the geological strength is within 400 kPa, such as mud layers, silt, and sand layers. Through the rotating cutting of bucket teeth, the resistance can be reduced and the drilling speed can be increased.

2. Crushing type:

Crushing drilling uses pick teeth for drilling. Most of them use double-bottom rock drilling buckets. According to the geological strength, friction or machine-locked drill rods can be configured. Gravel, mudstone, sandstone, shale, and medium weathering with a strength of 500 kPa to 1000 kPa can be drilled. Crushing drilling is achieved by transferring pressure to the alloy points on the pick teeth.

3. The toggle type can use double-bottom sand dredging and double-bottom rock drilling buckets, and can also be used with Bao’e teeth. Due to different types of geology, the drilling method changes accordingly. For example, in the pebble layer, the pebbles are arranged irregularly and cannot be cut and crushed. The toggle type drilling can be used. The drill rod is hung with the main reel, and the pebbles are toggled with the drill bucket tooth tip. After the pebbles are loosened, the drill bucket is placed under the float. This operation method avoids the strength and vibration of the pebbles.

4. Grinding type:

Use rock-entering barrel drills and tooth-shaft drills, and cooperate with machine-locked drill rods to drill rock formations calculated by single-circumferential compressive strength. The strength ranges from several megapascals to tens of megapascals. It is usually a rock-entering end-bearing pile, which is ground into the rock through the barrel drill ring cutting, or ground through the tooth-shaft drill. At the same time, the possibility of crushing cannot be ruled out according to the type, strength, brittleness, and cracks of the rock formation.

15 Operating Tips for Rotary Drilling Rigs:

1. At the site where the drilling rig is used, obstacles such as stones and other objects around the hole should be cleared according to the requirements of the drilling rig manual. 2. The distance between the work site and the power transformer or the main power supply line should be within 200m, and the voltage at startup should not exceed 10% of the rated voltage.
3. The motor and control box should have a good grounding device.
4. Before installation, check and confirm that the drill rod and each component are not deformed; after installation, the center line of the drill rod and the power head are allowed to deviate by 1% of the total length.
5. After installation, the frequency of the power supply should be the same as the pointer on the frequency conversion switch in the control box. If they are different, the frequency conversion switch should be used to convert them.
6. The drilling rig should be placed stably and firmly. The car-type drilling rig should be set up on its legs and support the tires. The tape should be adjusted by automatic fine-tuning or a plumb bob to keep it vertical.

7. Before starting, the operating lever should be placed in the neutral position. After starting, an idling test should be performed to check whether the instrument, temperature, sound, brake, and other functions are normal before operation. 8. When drilling, the drill rod should be slowly lowered first, and the drill bit should be aligned with the hole position. When the ammeter pointer deviates to the no-load state, the drill can be lowered. During the drilling process, when the ammeter exceeds the rated current, the drilling speed should be slowed down.
9. When the drill is stuck in the hole, the power supply should be cut off immediately, and the drilling should be stopped. It shall not be forced to start before the cause is found out.
10. During the operation, when it is necessary to change the rotation direction of the drill rod, it should be done after the drill rod stops completely.
11. When the power is off during operation, all controllers should be placed in a zero position, the power supply should be cut off, and all the drill rods should be pulled out of the hole in time so that the drill bit touches the ground.
12. When the drilling rig is running, the cable should be prevented from being entangled in the drill rod, and it must be supervised by a special person.
13. When drilling, it is strictly forbidden to remove the soil on the spiral blade by hand. If the drum spiral is found to be loose, the machine should be stopped immediately, and the operation can be continued after it is tightened.
14. After the operation, the drill rod and drill bit should be lifted out of the hole. The soil on the drill rod and spiral blades should be cleared first, and then the drill bit should be pressed to touch the ground, all parts should be braked, the joystick should be placed in the neutral position, and the power should be cut off.
15. When the drill bit wear reaches 20mm, it should be replaced.

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