Hole Enlargement Cone with Self-Tapping Threaded Ribs
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Solution Overview
Problem
Existing devices for enlarging holes in workpieces, such as plasterboard walls, lack an efficient mechanism to securely insert and expand the hole diameter using a pilot drill, as they do not effectively engage the inner wall for stable threading.
Innovation Solution
A frustoconical base body with a threaded cone shell surface, featuring self-tapping threaded ribs and a bearing bush, allows for initial insertion and subsequent screwing into the hole, enabling the formation of a stable thread within the workpiece, accompanied by a screwdriver for applying torque and a replaceable bearing bush for accommodating different pilot drills.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frustoconical base body is inserted into a hole for enlargement, then the hole can be prepared for diameter enlargement, but the base body lacks secure engagement with the inner wall for stable threading
Solution Approach 1:
The base body is divided into functionally distinct segments: a frustoconical outer surface for insertion and engagement, a cylindrical inner surface for pilot drill passage, and a threaded section for screwing into the workpiece. This segmentation allows each segment to perform its specific function optimally, with the threaded section providing secure engagement while the frustoconical section facilitates insertion.
Solution Approach 2:
The base body acts as an intermediary component between the pilot drill and the workpiece. It receives the pilot drill through its central opening, provides a threaded surface for secure engagement with the workpiece inner wall, and facilitates the hole enlargement process. This intermediary structure enables stable threading by mediating between the drilling operation and the workpiece material.
2Ease of manufacture
If a threaded rib structure is added to the base body, then self-tapping thread formation is enabled, but the device complexity increases
Solution Approach 1:
The threaded rib structure merges multiple functions into a single integrated component. The ribs are formed as integral parts of the base body, combining the threading function with the structural integrity of the base body itself. This eliminates the need for separate threading inserts or additional fastening components, achieving self-tapping capability without proportionally increasing device complexity.
Solution Approach 2:
The threaded ribs are designed with specific geometric parameters including a pitch between 1-5 mm (preferably 2 mm), vertex angles between 60°-100° (preferably 90°), and rib cross-sectional contours matching self-tapping thread profiles. These parameter optimizations enable effective self-tapping thread formation in the workpiece material while maintaining manufacturability and structural efficiency.
3Adaptability or versatility
If a bearing bush is inserted into the base body, then pilot drill accommodation is improved, but the device complexity increases
Solution Approach 1:
The bearing bush serves multiple functions: it accommodates the pilot drill during insertion, provides bearing support to reduce friction during the enlargement process, and can be replaced with different sized bushes to accommodate various pilot drill diameters. This multi-functionality increases adaptability while the modular design allows the bush to be a simple, easily replaceable component rather than a complex integrated structure.
Solution Approach 2:
The bearing bush provides dynamic adaptability to the device. It can be removed and replaced depending on the specific pilot drill being used, allowing the same base body to work with different drill sizes. This dynamic configuration enables versatility without requiring a different base body for each application, and the bush itself can rotate within the base body during operation to accommodate the rotating pilot drill.
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
This solution enables secure enlargement of hole diameters by forming a self-tapping thread within the workpiece, allowing for effective engagement with pilot drills of varying diameters, enhancing the stability and versatility of the hole enlargement process.
Implementation Method 1
it proves advantageous that the at least one threaded rib have a cross sectional contour that corresponds or at least equates to a self-tapping thread, so that a cutting edge formed by vertex lines can cut into the inner wall of the hole to be enlarged
Implementation Method 2
The screwdriver can be used to screw the base body into the hole to be enlarged, so as to exert a correspondingly large torque on the base body
Data Source
AI summary
A device for enlarging a hole with a frustoconical base body that can be inserted into a hole of a workpiece, and has an insertion opening for inserting a pilot drill of a hole saw. The frustoconical shell surface of the base body has a self-tapping thread, which can engage into the wall of the hole to be enlarged. A screwdriver is provided to apply the correspondingly large torque.