Cutting Bit Retention Assembly With Movable Pin
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Solution Overview
Problem
Existing cutting bit and support block assemblies in mining and construction machines experience premature wear and difficulty in disassembly due to severe operating conditions, leading to increased downtime and costs for replacement and maintenance.
Innovation Solution
A cutting bit retention assembly featuring a cutting bit holder with a shank section and a support block with a transverse bore, utilizing a retention pin that can be selectively positioned to securely engage and disengage the cutting bit holder, facilitating easy assembly and disassembly, and a camming pin to align and secure the components, thereby minimizing movement and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical connection is used to mount the cutting bit holder in the support block, then the cutting bit holder is securely retained during operation, but it becomes difficult to disassemble under severe operating conditions
Solution Approach 1:
The retention pin is designed to be movable between a first position (engaging the slot to secure the cutting bit holder) and a second position (disengaging to allow removal). This dynamic positioning enables the system to switch between secure retention during operation and easy disassembly during maintenance, resolving the contradiction between reliability and ease of repair.
2Duration of action of moving object
If the cutting bit holder is tightly mounted to minimize movement, then cutting bit life is maximized, but vibratory loosening occurs leading to premature failure
Solution Approach 1:
The camming pin automatically adjusts the mounting pressure of the cutting bit holder in the support block. As vibrations occur during operation, the camming surface allows the retention pin to self-adjust and maintain consistent engagement pressure, preventing loosening while minimizing excessive force that could cause premature failure. This self-regulating mechanism resolves the contradiction between maximizing cutting bit life and maintaining mounting stability.
Data Source
AI summary
A cutting bit retention assembly (399) that includes a cutting bit holder (500), which receives a cutting bit (58) and has shank (504) that extends into a bore (418) in a support (400). The shank section (504) of the cutting bit holder (500) presents a surface (530) defined by a notch (528) that selectively cooperates with a retention pin (670). A transverse bore (430) in the support (400) carries the retention pin (670). The retention pin (670) is selectively movable to any one of several positions. One position is a non-retaining position wherein the retention pin (670) does not engage the notch surface (530). Another position is a retaining position in which the retention pin (670) engages the notch surface (530) to urge the cutting bit holder into the cutting bit holder bore (418). Still another position is an ejecting position in which the retention pin (670) engages the notch surface (530) to urge the cutting bit holder (500) out of the cutting bit holder bore (418).