Drill Bit Chuck Assembly Simplification
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Solution Overview
Problem
Conventional drill bits for down-the-hole drill hammers are complex and difficult to manufacture, requiring specific structural features like splines and retaining rings, which complicate the manufacturing process and affect the weight and length of the drill hammer.
Innovation Solution
A drill bit design featuring a screw-threaded shank and an externally splined chuck with an outwardly extending shoulder, eliminating the need for a retaining ring and simplifying the manufacturing process by using screw threads along the shank length and splines only in the chuck and wear sleeve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional drill bit design with splines and retaining ring is used, then the bit can be securely retained in the chuck, but the manufacturing complexity increases and the bit requires minimum length affecting weight and drill hammer overall length
Solution Approach 1:
The patent removes the retaining ring from the drill bit design, extracting this separate component entirely. The retention function is achieved through the interaction between the chuck's outwardly extending shoulder and the bit's striking face, eliminating the need for a dedicated retaining ring and reducing manufacturing complexity
Solution Approach 2:
The patent combines the retention function with the existing structural elements. The chuck's outwardly extending shoulder serves both as a retention mechanism and as part of the chuck's structural design, while the bit's striking face serves both its primary function and as a retention interface, reducing the need for separate retention components
2Ease of operation
If conventional drill bit design with retaining ring is used, then the bit can accommodate axial movement, but the section of reduced diameter must be longer than the retaining ring thickness
Solution Approach 1:
By removing the retaining ring entirely, the patent eliminates the constraint that required a reduced diameter section longer than the ring thickness. The axial movement capability is maintained through the chuck's shoulder design, allowing the bit to be shorter while still accommodating necessary axial motion during operation
3Ease of manufacture
If screw threads are used along the shank length, then the manufacturing process is simplified, but the chuck must be externally splined with outwardly extending shoulder
Solution Approach 1:
The patent merges the retention function with the chuck's existing structural elements. The outwardly extending shoulder on the externally splined chuck serves both as part of the power transmission mechanism and as the retention interface for the bit, combining multiple functions into a single structural feature rather than requiring separate components
Data Source
AI summary
A percussive drill bit provided with an improved chuck assembly for a down-the-hole drill hammer. The bit has a head at its forward end with a shank extending from the head. The shank is screw threaded along its length. A reciprocating chuck is provided as a sleeve with internal screw thread as corresponding to those of the shank. The shank is releasably secured in the chuck with the read end of the shank providing a striking face. An arrangement of external splines on the chuck, and a retaining shoulder at its rear end, provide for the required guided movement of the chuck within a drill hammer wear sleeve.