Special Facilities for Testing Rock Drilling Tools: the Importance of Improving Operating Efficiency and Safety

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With the rapid development of industrialization, rock drilling tools have been widely used in various projects. However, since the quality and performance of rock drilling tools have a vital impact on the safety and efficiency of the entire project, regular testing is crucial.

The importance of rock drilling tools testing

rock drilling tools

Rock drilling engineering is an important technology widely used in mining, construction, water conservancy, and other fields. Rock drilling tools are essential tools in rock drilling engineering. Its performance and quality directly affect the project’s construction efficiency, safety, and quality. Issues with the quality or performance of rock drilling tools can lead to engineering accidents, posing a potential threat to the lives of personnel involved. Hence, regular testing of rock drilling tools is paramount to ensure their reliability and safety in operations.

Professional facilities for rock drilling tool inspection include waveform thread inspection tools, special taper inspection measuring tools, weld static shear strength and fixed tooth strength inspection, professional inspection plates, closed-loop displacement measurement systems, etc. These facilities can detect key performance indicators such as hardness, toughness, wear resistance, and impact toughness of rock drilling tools to ensure that they meet engineering needs.

Special facilities for testing rock drilling tools

rock drilling tools

Waveform thread inspection tools

Threaded drilling tools widely adopt waveform, trapezoidal, and composite threaded connection structures. Among them, waveform and trapezoidal threads are the most broadly used. The waveform threads have been included in international standards and national standards.

There are three main methods used to detect waveform threads:

1. Directly use shank adapters, coupling sleeves, and other products as testing tools for mutual matching testing (or use special-standard threaded sample rods and coupling sleeves for mutual matching testing).

2. Use a tool microscope or profilometer for inspection.

3. Use a specific waveform thread gauge.

When using product or sample rods together with sample sets for test gauges, the accuracy of the test can be compromised, making it challenging to control the scale and ensure product quality. Using a tool microscope or profilometer for inspection allows for direct measurement of thread size, ensuring high inspection accuracy. However, product testing, particularly for internal threads, necessitates complex sample preparation with stringent accuracy requirements, slow testing speeds, inconvenience in use, and high investment in testing equipment. This method is confined to laboratory settings and for new product development or gauge services, such as testing sample rods and sets.

An alternative, simpler, and more practical approach involves using a specialized wave thread gauge for product inspection. This gauge, designed for a specific fixed value, offers advantages such as a straightforward structure, easy usability, high detection efficiency, and no damage to the measured piece. Consequently, it has found widespread application in threaded drilling tool testing.

Special testing measuring tool for taper

Smooth taper surround inspection and plug gauges are available for detecting the geometric dimensions and contact status of the tapered drill rod and the taper hole of the taper bit. The principle of its detection is to find out the allowable variation range in the axis direction based on the limit deviation of the datum size of the taper and then machine the corresponding steps on the gauge based on this value as a mark of detection control.

Weld static shear strength and fixed tooth strength testing

button bit

The static shear strength of the rock drill bit weld undergoes testing on a universal material testing machine.

The fixed tooth strength of the button bit is an index of the tightness of the tungsten carbide columns and teeth on the bit shell. During testing, it is necessary to prepare samples for the rock drill bit. The sampling of drill bits is complex and inefficient. During the sample preparation process, use a grinding wheel cutter or other cutting equipment to cut off the head of the button bit near the bottom of the tungsten carbide button and grind off the shell metal at the bottom of the tungsten carbide button to expose the bottom surface of the tungsten carbide button. Then, on the material testing machine, a special indenter is used to push out the tungsten carbide button from the bottom. Based on the maximum ejection load and the area of the tungsten carbide button flank, the fixed tooth strength is calculated, but it is not suitable for the bottom strength test of the welded fixed tooth process.

Professional inspection plates

For tapered drill rods, integral drill rods, and shank rods, a special inspection plate should be used to detect the end face of the shank end, the verticality of the rod axis, the coaxially within 100mm on both sides of the drill shoulder, the curvature of the rod and other parameters. The structure of the flat plate is quite simple. A groove longer than the radius of the drill shoulder is machined on one end of the flat plate, and an indexing head, a movable support frame for the drill rod, and a V-shaped block are installed. The testing measuring tools typically include outer diameter dial indicators, dial indicators, feeler gauges, height vernier calipers, and steel rulers.

Closed loop displacement measurement system

In the inspection process of the geometric dimensions of rock drilling tools, measuring tools such as gauges and templates are generally used. Using these measuring tools in testing rock drilling tools introduces the possibility of human errors by inspectors, potentially compromising the precision and accuracy of the detection process. The closed-loop displacement measurement system is a displacement monitoring system composed of a digital display, a preamplifier, a matching transformer, a wired induction synchronizer, and a dedicated traveling mechanism, which can effectively solve the above problems.

Conclusion

With the continuous development of the engineering field, the importance of rock drilling tool inspection has become increasingly prominent. Special facilities for rock drilling tool testing are the key to ensuring the safety and efficiency of rock drilling projects. By using these facilities, we can conduct comprehensive testing of the rock drilling tools, discover and deal with existing problems promptly, and ensure the smooth progress of the project. In the future, with the continuous development of science and technology, we look forward to more and more advanced facilities to improve the safety and efficiency of rock drilling projects.

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