Rock Drilling Feed Control via Pressure Flow Switching
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Solution Overview
Problem
Existing rock drilling technologies experience jerky drilling and increased risk of drill string sticking, leading to reduced productivity and potential damage, due to abrupt reverse movements when rotation pressure exceeds certain thresholds.
Innovation Solution
A method combining pressure and flow control of the feed motor to regulate the drilling machine's movement, switching from pressure control to flow control as rotation pressure increases, allowing for gentle and flexible control, reducing the risk of drill string sticking and enhancing operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotation pressure is increased when the drilling machine tends to get stuck, then the rotation moment increases and the drill bit can rotate through the stuck condition, but the drilling becomes jerky and the drilling machine is abruptly pulled backwards which is harmful
Solution Approach 1:
The control system initiates reverse feed movement before the rotation pressure reaches the critical 'limit drill stuck' level. By detecting the tendency towards sticking through monitoring rotation pressure trends and operator input, the system performs preliminary reverse movement to prevent complete sticking, thereby avoiding the need for abrupt corrective actions later.
Solution Approach 2:
The system dynamically adjusts the feed movement based on real-time rotation pressure conditions. When rotation pressure increases indicating a tendency to stick, the control system automatically reverses the feed direction. This dynamic response allows smooth transition between forward and reverse movement, eliminating jerky operations while maintaining reliability.
2Reliability
If the protection-against-drilling-stuck function is initiated at high rotation pressure, then the drill string sticking is prevented, but the drilling machine is abruptly pulled backwards causing negative effects and potential harm
Solution Approach 1:
The system initiates reverse feed movement as a preliminary protective action when rotation pressure shows signs of excessive increase, before the drill string completely sticks. This early intervention prevents the need for more forceful corrective measures that could damage the drilling machine, while still maintaining the drill string in a functional state.
Solution Approach 2:
The control system provides cushioning by gradually initiating reverse feed movement rather than abrupt reversal. This cushioning effect absorbs the mechanical shock and stress that would otherwise be transmitted to the drilling machine components, preventing damage while still preventing drill string sticking.
3Reliability
If the feed pressure is reduced to minimum level when rotation pressure exceeds desired value, then the risk of drill string sticking is reduced, but the control becomes indefinite especially during the start of control process
Solution Approach 1:
The control system continuously monitors rotation pressure and provides feedback to the feed control mechanism. When rotation pressure exceeds the desired value, the system feeds back this information and automatically adjusts feed pressure downward. This closed-loop feedback ensures definite and responsive control, eliminating the indefiniteness present in open-loop systems especially during transient conditions.
Solution Approach 2:
The control system is designed to automatically regulate feed pressure based on rotation pressure conditions without requiring external intervention. The system self-adjusts by reducing feed pressure when rotation pressure increases, providing definite control behavior during the start of control processes and throughout operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the frequency and severity of drill string sticking incidents, increases productivity, and minimizes loads on the drilling machine and drill steel by initiating gentle backward movement before the drill stuck function is activated, thus raising the 'limit drill stuck' threshold and improving operational economy.
Implementation Method 1
control of the feed of a rock drilling machine by means of a feed motor (M) in which said feed motor (M) is controlled by means of a control means (S) in which a feed pressure and a feed flow respectively are reduced respectively increased in proportion to a change of a parameter value
Implementation Method 2
a combination of pressure and flow control of the feeding to the feed motor
Data Source
Figure 1
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AI summary
A method and a device for controlling the feeding on a feed beam (3) of a to and fro movable rock drilling machine (2), which includes a percussive device and a rotation motor providing a rotation moment, wherein a parameter related to the rotation moment is monitored and the feeding is controlled by flow control as a response to variation of the value of the parameter, wherein a feed flow to a fluid motor means providing the feed is reduced as a function of a change of the parameter value corresponding to an increase of the rotation moment over a first level. For parameter values corresponding to the rotation moment being below the first level, feeding is controlled by pressure control as a response to the variation of the value of the parameter, wherein a feed pressure for said fluid motor means is reduced as a function of a change of the parameter value corresponding to an increase of the rotation moment. The invention also concerns a rock drilling machine and a drilling rig.