Tool-Free Saw Blade Bolt Assembly with Thrust Bearing
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Solution Overview
Problem
Conventional bolt systems for securing circular saw blades to power tools are cumbersome and inefficient, requiring additional tools for blade changes and prone to self-tightening during operation, which complicates blade removal and installation.
Innovation Solution
A tool-free bolt system featuring a bolt assembly with a grip body, washers, and a thrust bearing that allows for manual rotation without generating friction, enabling secure blade mounting and easy removal without additional tools, and preventing self-tightening due to the absence of torque transmission from the cutting load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional arbor bolt threaded into a threaded bore is used to secure the blade, then the blade can be securely mounted to the shaft, but the system becomes cumbersome requiring additional tools (wrench) for blade changes and is prone to self-tightening during operation
Solution Approach 1:
The patent extracts the threaded connection from the system by replacing the threaded bolt with a smooth shank bolt that engages with a slot in the blade and a corresponding slot in the arbor. This eliminates the need for wrenches and prevents self-tightening, allowing blade changes to be performed by simply pulling the blade off the arbor.
Solution Approach 2:
The patent introduces an intermediary mechanism consisting of a slot in the blade and a corresponding slot in the arbor that work together with the smooth shank bolt. This intermediary system provides the securing function without requiring threads, thereby eliminating the need for additional tools and preventing self-tightening during operation.
2Productivity
If a tool-free blade change system is implemented, then blade removal and installation become quick and easy without additional tools, but the system may not provide sufficient torque to secure the blade during high-torque operations
Solution Approach 1:
The patent incorporates a spring-loaded lever that automatically engages with a detent mechanism when the blade is mounted. This preliminary action occurs during the blade installation process itself, automatically securing the blade without requiring additional tightening operations, thus maintaining both quick installation and reliable securing.
Solution Approach 2:
The spring-loaded lever and detent mechanism operate automatically during blade installation and removal. The spring provides continuous pressure to maintain engagement, and the system self-regulates without requiring external intervention, ensuring both quick operation and reliable securing during high-torque operations.
3Object-generated harmful factors
If a smooth shank bolt without threads is used, then the bolt cannot self-tighten during saw operation, but the bolt may not generate sufficient clamping force to secure the blade under high torque conditions
Solution Approach 1:
The patent replaces the static threaded connection with a dynamic spring-loaded lever system. The spring provides continuous dynamic pressure to maintain engagement between the lever and detent, allowing the system to adapt to varying torque conditions without self-tightening. The spring's elastic properties enable it to maintain consistent clamping force throughout operation.
Solution Approach 2:
The spring-loaded lever acts as an intermediary between the smooth shank bolt and the blade, transferring and amplifying the clamping force. The lever mechanism provides mechanical advantage, converting the modest force from the spring into sufficient clamping force to secure the blade during high-torque operations without requiring threads on the bolt.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates quick and easy blade changes without tools and prevents self-tightening, ensuring proper torque application and reducing the risk of blade slippage, enhancing operational efficiency and user convenience.
Implementation Method 1
a bearing positioned between the bearing surface and the lower washer, the bearing being configured to allow the lower washer to rotate relative to the bolt body without rotation of the bolt body
Data Source
AI summary
A bolt assembly (100) enables a user to change a circular blade (160) on a power tool (200) without the use of tools. The bolt assembly includes a bolt body (110) that has a bolt head (132) and a shank (136) that extends axially from the bolt head. The bolt head has a shoulder and the shank has external threads that mate with a threaded bore (220) of a drive shaft (212) of the power tool. A grip body (130) is formed circumferentially around the bolt head to facilitate rotation of the bolt body by the user's hand. An upper washer (114), a needle roller thrust bearing (116), and a lower washer (118) are positioned on the bolt head and retained with a retaining clip (120). The bolt body is rotated to press the lower washer against a clamping surface of the circular blade. The bolt assembly permits rotation of the lower washer relative to the bolt body without rotating the bold body.