The button bit is a drilling tool widely used in rock drilling engineering. It has the characteristics of free button arrangement, fast drilling speed, and a long grinding cycle. Ensuring the button bit‘s proper functionality and extended service life requires adherence to correct usage and grinding methods.
Correct use of button bit
Choose the right button bit
Select a suitable button bit based on the hardness of the rock and operational requirements. Additionally, ensure that the chosen button bit aligns with the model and power specifications. It can ensure optimal performance and longevity.
Keeping button bits clean
Before using the button bit, inspect its surface for cleanliness, ensuring there are no residues or debris. If any residue is detected, promptly clean it to prevent any adverse effects on performance and lifespan.
Correctly install the button bit
During the installation of the button bit, ensure a secure connection to the rock drill to prevent loosening or accidental detachment. Additionally, confirm that the button bit is installed in the correct direction to facilitate smooth and effective drilling operations.
Control drilling speed and pressure
When utilizing a button bit, it’s crucial to control the rock drilling speed and pressure by the power and type of the rock drill being employed. It ensures optimal performance and avoids unnecessary strain or damage to the equipment. Too high a rotational speed will accelerate the wear of the drill bit and increase the risk of breakage of the button, especially the button on the outer edge of the drill bit.
Regular inspection and maintenance
Regularly inspect the wear of the button bit during use. If significant wear or damage is detected, promptly replace or repair the button bit. It is advisable to conduct regular checks on the button after each blast hole is finished drilling, addressing any issues promptly. Additionally, ensure regular inspections and maintenance of the rock drill to guarantee its proper and efficient operation.
Principle of grinding button bit
To improve the service life of drill bit, it is not possible to wait until the drill bit wears down to a very low drilling speed. Instead, the principles of “early repair and less grinding” and “frequent repair and fine grinding” should be adopted, and the drill bit should be ground in time after wear. When the button wears to 1/3~1/2 of its column diameter, or when the surface of button shows hotlines and a “snakeskin” phenomenon, it should be ground in time to ensure the drilling speed and rock drilling performance of drill bit and avoid drill bit from breaking button due to stress concentration. When necessary, the outer cylindrical working surface of the grinding drill bit can be used to grind the outer cone of drill bit and the shallower powder discharge groove.
Precautions for grinding the button bit
Reasonably arrange the grinding time
① Determine whether the button bit needs to be ground. It is generally determined by the size of the worn surface of the button. When the drill bit is worn, the resistance to rock penetration increases, the energy transfer rate decreases, the drilling rate decreases, and the stress on the drill rod increases accordingly. Therefore, when the drilling rate drops sharply, drill bit should be reground in time to restore its original shape and reduce the rock penetration resistance to a predetermined level.
② Since the rock drilling conditions vary greatly, the grinding interval of the drill bit cannot be fixed, but we can make reference to the resharpening interval according to the production experience and the hardness of the ore rock, formulate a reasonable drill bit grinding plan, and resharpen the drill bit regularly. For example, according to the degree of wear of the drill bit, the dull drill bit should be removed and ground every 5~10 holes. Adopting this mandatory system of regular grinding of drill bits can avoid economic losses caused by human factors and bring many economic benefits, such as prolonging the service life of drill bits, drill rods, and coupling sleeves, increasing the drilling speed, reducing the working stress of rock drilling tools and drilling rig parts, reducing the chance of failure of rock drilling tools, and improving the straightness quality of drilling. In addition, on-site operators should also closely observe the rock drilling conditions and replace in time those drill bits that do not work properly during the planned grinding period.
Correctly master the grinding method
The direct purpose of grinding the button bit is to restore it to its original geometry. The correct grinding process and method are not only the quality assurance of drill bit grinding but also the basic functional requirements for grinding tools and equipment.
Preparation before grinding
Before grinding the button bit, prepare the resharpening tools, equipment, coolant, and other necessary items. Ensure that the grinding site is both clean and safe for the procedure. It helps maintain efficiency, safety, and the overall effectiveness of the button bit resharpening process.
Precautions when grinding
When grinding, pay attention to the following matters.
- Since the wear of button is greater than the drill bit body when drilling rock when grinding the drill bit, part of drill bit body at the head end should be removed first, to restore the height of the button protruding from the drill bit body.
- Select suitable abrasive materials according to different carbide button grades, and pay attention to the metallographic organization of the abrasive materials, especially do not choose abrasives with too hard a texture.
- Pay attention to cooling when grinding the drill bit.
- During the grinding, pay attention to the measurement of drill bit with the button sample to ensure the correct geometric dimensions of the drill bit and timely adjustment of the machine parameters.
- For the completely failed button, remove them completely with an ordinary grinder.
Inspection and adjustment
After grinding, the button bit should be inspected and adjusted. Check whether its surface is smooth and has no cracks or burns; check whether the buttons are even and not distorted or broken. If problems are detected, they should be adjusted or re-grinded in time. Simultaneously, adjust the parameters of the rock drill to ensure its proper and smooth operation during the button bit resharpening process. This adjustment is essential for maintaining the performance and longevity of both the rock drill and the button bit.
In short, the correct use and grinding of button bits is the key to improving engineering efficiency and extending the service life of tools. It is also a crucial factor in reducing costs and ensuring operating safety. A profound understanding of button bit usage and mastery of accurate grinding techniques enable us to respond effectively to diverse engineering challenges, improving overall operating efficiency and safety.
