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CN-116547441-B - Method and system for detecting the condition of a joint of a drill string

CN116547441BCN 116547441 BCN116547441 BCN 116547441BCN-116547441-B

Abstract

The invention relates to a method for determining the condition of at least one joint of a drill string (107) of a drilling machine, the drilling machine comprising a percussion device comprising a percussion element for introducing a shock wave into the drill string (107), and a sensor for sensing a stress wave in the drill string (107) caused by the impact of the percussion element, the method comprising determining a representation of an incident stress wave caused by the percussion element when the percussion element introduces the stress wave into the drill string (107), determining a representation of a reflected wave representing the reflection of the incident stress upon reaching the at least one joint, estimating the stiffness of the at least one joint by estimating the force exerted by the incident wave on the at least one joint and the displacement caused by the force, and generating a signal representing the condition of the at least one joint based on the estimated stiffness.

Inventors

  • GOTHBERG MATHIAS
  • ENBLOM SAMUEL

Assignees

  • 安百拓凿岩有限公司

Dates

Publication Date
20260508
Application Date
20211130
Priority Date
20201221

Claims (17)

  1. 1. A method for determining a condition of at least one joint (205,206,207,208) of a drill string (107) of a drilling machine (100), the drilling machine (100) comprising a percussion device (105), the percussion device (105) comprising a percussion element (115) for introducing a shock wave into the drill string (107), and a sensor (209) for sensing a stress wave in the drill string (107) caused by a shock of the percussion element (115), the method comprising the following operations when the percussion element (115) introduces a stress wave into the drill string (107): determining a representation of an incident stress wave caused by the impact element (115); determining a representation of a reflected stress wave representing a reflection of the incident stress wave upon reaching the at least one joint (205,206,207,208); Estimating a stiffness of the at least one joint (205,206,207,208), estimating the stiffness by estimating a force exerted by the incident stress wave on the at least one joint (205,206,207,208) and a displacement caused by the force, and A signal representative of a state of the at least one joint (205,206,207,208) is generated based on the estimated stiffness.
  2. 2. The method of claim 1, further comprising: By multiplying the sum of the representation of the incident stress wave and the representation of the reflected stress wave by the cross-sectional area of the component of the drill string (107) , ) To estimate the force.
  3. 3. The method of claim 1 or 2, further comprising, prior to estimating the stiffness of the joint: at least one of the representation of the incident stress wave and the representation of the reflected stress wave is filtered.
  4. 4. A method according to any one of claims 1 to 3, further comprising: Before estimating the stiffness of the joint, an offset in the representation of the incident stress wave and/or the reflected stress wave is removed, the offset being related to signal levels caused by other reflections in the drill string (107).
  5. 5. The method of any one of claims 1 to 4, further comprising: the stiffness is estimated as a change in a force exerted by the incident stress wave on the at least one joint (205,206,207,208) relative to a change in a displacement of the joint caused by the force.
  6. 6. The method of claim 5, further comprising: When the change in force exceeds a threshold value relative to the change in displacement, it is determined that the joint is tightened.
  7. 7. The method of any one of claims 1 to 6, further comprising: monitoring an estimated stiffness of the at least one joint (205,206,207,208), and One or more drilling control parameters are adjusted by means of the rig control system based on the monitored estimated stiffness of the at least one joint (205,206,207,208).
  8. 8. The method of any of claims 1 to 7, further comprising: the stiffness of a plurality of joints or all joints in the joint (205,206,207,208) of the drill string (107) is estimated.
  9. 9. The method of any one of claims 1 to 8, further comprising, when all joints (205,206,207,208) are to be loosened: Determining whether all joints (205,206,207,208) are loose by means of an estimation of the stiffness of the joints (205,206,207,208), and When all of the joints (205,206,207,208) are determined to be loose, a signal is generated.
  10. 10. The method of claim 9, further comprising: controlling the percussion element (115) to apply a percussion to the drill string (107) by means of a drilling machine control system, Continuously determining whether all joints (205,206,207,208) are loose by means of an estimation of the stiffness of the joints (205,206,207,208), and When it is determined that all joints (205,206,207,208) are loose, the application of shock to the drill string (107) is stopped.
  11. 11. The method according to any one of claims 1 to 10, further comprising determining the state of a specific joint by estimating when the sensor (209) can detect a reflection of the incident stress wave originating from the specific joint over time.
  12. 12. The method according to any of claims 1 to 11, further comprising the following operation when a first joint (205) is at a distance from the sensor (209) such that the incident stress wave is mixed with the reflected stress wave: -compensating the representation of the incident stress wave for the reflection such that the representation of the incident stress wave is effective when used for estimating the stiffness of a joint (206,207,208) further away from the sensor (209).
  13. 13. The method of any one of claims 1 to 12, further comprising: a representation of the incident stress wave is determined with a first sensor element and a representation of the reflected stress wave is determined with a second sensor element.
  14. 14. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the method of any one of the preceding claims.
  15. 15. A computer readable medium comprising instructions which, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 13.
  16. 16. A system for determining a state of at least one joint (205,206,207,208) of a drill string (107) of a drilling machine (100), the drilling machine (100) comprising a percussion device (105), the percussion device (105) comprising a percussion element (115) configured for introducing a shock wave into the drill string (107), and a sensor (209), the sensor (209) being configured for sensing a stress wave in the drill string (107) caused by a shock of the percussion element (115), the system being characterized in that the system is configured to, when the percussion element (115) introduces a stress wave into the drill string (107): determining a representation of an incident stress wave caused by the impact element (115); determining a representation of a reflected stress wave representing a reflection of the incident stress wave upon reaching the at least one joint (205,206,207,208); Estimating a stiffness of the at least one joint (205,206,207,208), estimating the stiffness by estimating a force exerted by the incident stress wave on the at least one joint (205,206,207,208) and a displacement caused by the force, and A signal representative of a state of the at least one joint (205,206,207,208) is generated based on the estimated stiffness.
  17. 17. Rock drilling rig (100), characterized in that it comprises a system according to claim 16.

Description

Method and system for detecting the condition of a joint of a drill string Technical Field The present invention relates to mining, and more particularly to a method and system for detecting the condition of a joint of a drill string. The invention also relates to a computer program implementing the method according to the invention. Background Rock drilling rigs can be used in many fields of application. For example, rock drilling rigs may be used for tunnelling, surface mining, underground mining, rock reinforcement, raise boring, and may be used for example for drilling blastholes, grouted holes, rock bolt-mounting holes, water and other wells, piling, foundation boring, and the like. Therefore, the rock drilling machine has wide application. The actual breaking of the rock is usually carried out by means of a drill bit that contacts the rock, wherein the drill bit is usually connected to the drilling machine by means of a drill string. Drilling may be done in various ways and is e.g. percussive, wherein, for example, a percussive element of the drilling machine, e.g. in the form of a percussive piston, repeatedly impacts the drill bit, typically by striking, connecting the drill bit to the drill string of the drilling machine to transmit percussive pulses, i.e. stress waves, in the form of shock waves to the drill bit and further into the rock. Percussion drilling may be combined with rotation to obtain a knob of the drill bit, the drilling of which the insert hits new rock on each stroke, thereby improving the efficiency of the drilling. The drill bit may be pressed against the rock during drilling by means of a feed force to ensure that as much impact energy as possible from the percussion device is transferred to the rock. In order to obtain an efficient percussion drilling process, it is important to set various drilling parameters in such a way that percussion drilling is performed in a manner that allows as much as possible of the percussion wave energy caused by the percussion element to be transferred into the rock in order to break the rock. In the event that the drill bit is not firmly pressed against the rock, energy may be reflected to an undesirable extent and returned to the drilling machine, possibly resulting in excessive wear or damage. This also occurs if the joints of the drill string (typically threaded joints) are not sufficiently tightened. Harmful reflections may also occur if the shock wave energy is too low in relation to the force by means of which the drill string is pressed against the rock. When drilling longer holes in, for example, rock, a plurality of drill rods may be engaged, for example by being screwed together, to lengthen the drill string so that a hole of a desired length may be drilled. Disclosure of Invention It is an object of the present invention to provide a method and a system which can identify a loose joint, in particular a loose threaded joint, during percussive drilling. According to the present invention there is provided a method for determining the condition of at least one joint of a drill string of a drilling machine, the drilling machine comprising a percussion device comprising a percussion element for introducing a shock wave into the drill string, and a sensor for sensing a stress wave in the drill string caused by the impact of the percussion element, the method comprising determining a representation of an incident stress wave caused by the percussion element when the percussion element introduces the stress wave into the drill string, and determining a representation of a reflected wave representing the reflection of the incident stress upon reaching the at least one joint. The stiffness of at least one joint is estimated by estimating a force exerted by the incident wave on the at least one joint and a displacement caused by the force, and a signal representative of a state of the at least one joint is generated based on the estimated stiffness. As mentioned above, properly tightened joints are a requirement for efficient drilling. The tightening of a normal threaded joint is also typically made firm by the passage of shock waves through the joint during drilling. However, in adverse circumstances, the joint may become loose, which degrades drilling and the threaded joint is subject to excessive wear. There are also situations where a loose joint is desired. After drilling, the drill string is retracted and the drill rods are loosened from each other. However, during drilling, the joint may become so firmly screwed due to the shock waves passing through the joint during drilling that the joint cannot be loosened by means of the rotation motor of the drilling machine alone. To solve this problem, for example, the operator may end drilling by letting the percussion device apply a short impact to the drill string without pressing the drill string against the rock being drilled in order to loosen the joint. Whether this is successful may depend