Grinding tool for grinding buttons on a rock drill bit

Abstract

The present disclosure provides a grinding cup for detachable connection to the output drive shaft of a grinding machine for grinding buttons on drill bits or cutters. The grinding cup has top and bottom surfaces and consists of a lower grinding section and an upper body section co-axial with the grinding section to form a grinding cup with a centrally disposed recess formed in the bottom surface of the grinding section having the desired profile for the button to be ground. The improvement of the present invention is characterized by the upper body section having a centrally disposed upright drive section sized and shaped to fit within a co-axial recess in a free end of the output drive shaft. The upright drive section has a first support section extending from a top surface of the upper body section and a co-axial drive section on the upright drive section extending from a top surface of the first support section to a free end of the upper drive section. The co-axial drive section has a lower cam portion with an elliptical cross section, shaped and sized to fit within a corresponding pair of lobed grooves in a sidewall of the co-axial recess in the output drive shaft and an upper portion, co-axial with the lower cam portion having a circular cross-section slightly less than the diameter of an upper portion of the co-axial recess in the output drive shaft. Retaining means for detachably connecting the grinding cup to the output drive shaft of the grinding machine are provided on the upright drive section, preferably on or in association with the first support section.

Description

Background technique [0001] This disclosure relates to working bits or hard metal inserts for grinding rock drill bits (percussion or rotary), tunnel boring machine tools (TBM) and convex hole machine tools (RBM), and more particularly but not exclusively Improvements in apparatus for grinding cutters or buttons of rock drill bits or cutters. [0002] During drilling operations, the cutting teeth (ie, buttons) on a drill bit or cutter flatten (wear) after continued use. Regular maintenance of drill bits or cutters by regrinding (sharpening) the buttons so that they essentially return to their original profile improves drill / cutter life, increases drilling speed and reduces drilling costs. Regrinding should be carried out when the button wear is preferably one-third to at most one-half the button diameter. [0003] Manufacturers have developed a range of different manual and semi-automatic grinding equipment, including hand-held grinders, single and double-arm grinders, and g...

AI Technical Summary

Problems solved by technology

[0005] A long-standing problem with these types of grinders is vibration and noise due to high RPM, wear, large compressor requirements for pneumatic systems, and long grind times per button for larger sizes

Lack of operational stability often results in vibrations and resonances during grinding

Vibration and / or resonance also directly lead to increased wear rates of all moving parts of the grinding equipment such as bearings, joints, etc., and can potentially interfere with settings within the grinding equipment's operational control circuitry

Additionally, the lack of operational stability leads to increased wear on the output drive shaft (rotor) and all critical drive / contact surfaces of the grinding cup that provide consistent contact between the grinding cup and / or adapter and the rotor during operation. , correct alignment

Operating instabilities and associated vibrations and / or resonances are major factors leading to deterioration of the preferred built-in profile of the cavity in the grinding zone of the grinding cup

This directly leads to a deterioration of the profile of the restoring button

The net effect is a significant loss in the expected overall drilling performance of the bit or cutter being used

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