Anchor Hole Undercut Drilling With Controlled Centrifugal Force
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Solution Overview
Problem
Conventional methods for forming anchor holes using undercut drill devices are inefficient for small diameter holes, as they require significant centrifugal force and are time-consuming, and cannot be easily adapted for metal expansion anchors.
Innovation Solution
A method using a diameter expansion drill bit with cutting-blade portions that apply a centrifugal force of at least 0.75 N to grind a diameter expansion portion, allowing for efficient formation of anchor holes with a diameter expansion of 0.3 mm or more, utilizing a drill bit that rotates between 2500 rpm and 40000 rpm and drives for 5-20 seconds, with diamond cutting-blades of specific grain sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional undercut drill device is used to form a diameter expansion portion, then the device can be applied to large diameter anchor holes, but the device configuration becomes complicated and cannot be easily adapted to small diameter anchor holes
Solution Approach 1:
The drill bit is segmented into multiple cutting-blade portions (at least three) arranged radially, allowing the device to handle different diameter requirements through selective activation or configuration of cutting blades, thereby reducing overall device complexity while maintaining versatility across small and large diameter anchor holes
Solution Approach 2:
The drill bit design integrates multiple functions into a single tool: it can drill anchor holes of various diameters, form diameter expansion portions, and adapt to different anchor types (resin-based and metal expansion anchors) using the same basic configuration, eliminating the need for specialized devices for different applications
2Productivity
If the centrifugal force is increased to grind the diameter expansion portion quickly, then the operation efficiency improves, but the weight and turning radius are restricted by the anchor hole diameter
Solution Approach 1:
The cutting-blade portions are positioned at specific radial distances from the rotation axis, with at least one blade located at a greater radial distance to maximize centrifugal force application for efficient grinding, while maintaining an overall compact drill bit structure that fits within small diameter anchor holes
Solution Approach 2:
The drill bit design allows for adjustment of cutting-blade portion parameters including radial position, weight distribution, and arrangement configuration, enabling optimization of centrifugal force application for quick grinding while adapting to the constraints of different anchor hole diameters
3Productivity
If the angular speed is increased to generate sufficient centrifugal force, then the grinding efficiency improves, but the angular speed is restricted by the number of revolutions of the drill main-body
Solution Approach 1:
The drill bit design exploits the radial dimension by positioning cutting-blade portions at optimized radial distances from the rotation axis, allowing sufficient centrifugal force to be generated at moderate angular speeds that are achievable with standard drill main-bodies, thereby achieving efficient grinding without requiring excessively high rotation speeds
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
Enables the formation of anchor holes with a diameter expansion portion in a short time and with high operation efficiency, suitable for both small and large diameter holes, including those for metal expansion anchors, by simplifying the device configuration and optimizing centrifugal force application.
Implementation Method 1
the plurality of cutting-blade portions of the diameter expansion drill bit is slid in a radial direction by a centrifugal force to grind a part of the prepared-hole portion to form a diameter expansion portion
Data Source
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AI summary
[Object] To provide a method for forming an anchor hole and a diameter expansion device by which a centrifugal force can be appropriately adjusted when a cutting-blade portion is moved in a radial direction by the centrifugal force to grind a diameter expansion portion. [Solution Means] In a method for forming an anchor hole 1 for a post-installed anchor 100 in which a diameter expansion drill bit 20 is inserted and rotated in a prepared-hole portion 3 bored in a concrete fixing body 2 and a cutting-blade portion 31 of the diameter expansion drill bit 20 is moved in a radial direction by a centrifugal force to grind a part of the prepared-hole portion 3 to form a diameter expansion portion 4, the minimum value of the centrifugal force applied to grind the diameter expansion portion 4 is 0.75 N and preferably 1.1 N.