Drill Support Pad Asymmetric Arch for Hole Wall Contact Control
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Solution Overview
Problem
Previous support pads for drill bodies have geometrically determined entering surfaces that result in unpredictable contact with the hole wall, leading to impaired centering and hole quality, and sharp edges that can dig into the hole edge during rotation.
Innovation Solution
The support pad design features a convexly arched entering surface with a dislocated secondary center axis relative to the primary center axis, allowing controlled contact and eliminating sharp edges by grinding the entering surface and cylindrical outside in two simple machining operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional conical entering surface is used on support pads, then the support pad can enter the hole, but the contact point with the hole wall becomes unpredictable and cannot be controlled
Solution Approach 1:
The entering surface is designed with an asymmetric convex arch shape where the rear borderline forms a convex arc line with the crest facing forward. This asymmetric geometry ensures that the crest makes contact with the hole wall at a predetermined location before the rest of the borderline enters, providing controlled contact point while maintaining relatively simple manufacturing through standard grinding operations.
2Manufacturing precision
If the entering surface is ground to achieve precise contact control, then contact precision improves, but manufacturing cost increases due to additional finishing operations
Solution Approach 1:
The convex arch shape with the specific geometric relationship between the entering surface and cylindrical outside is designed during the initial support pad formation. This preliminary geometric configuration ensures that after standard grinding of the entering surface and cylindrical outside, the crest of the rear borderline automatically makes contact at the predetermined location without requiring additional manual finishing or edge smoothing operations.
3Productivity
If support pads are designed for mass production, then productivity increases, but achieving precise contact control becomes more difficult
Solution Approach 1:
The invention specifies precise geometric parameters for the entering surface, including the convex arch shape where the rear borderline forms an arc line with the crest facing forward, and the specific relationship between the entering surface and cylindrical outside. These parameter definitions allow the support pads to be manufactured using standard grinding processes in series production while ensuring consistent predetermined contact control across all mass-produced units.
Data Source
AI summary
In one aspect, the invention relates to a support pad intended for metal machining drills and of the type that comprises an outside (19), an inside, front and rear end surfaces (21, 22), as well as a pair of spaced-apart side surfaces (24), between the outside (19) and at least the front end surface (21) a convexly arched entering surface (27) being formed that extends between, on one hand, a pair of front and rear borderlines (28, 29), the rear one (29) of which borders the outside (19), and, on the other hand, two tangentially spaced-apart side borderlines (30, 31). According to the invention, the rear borderline (29) of the entering surface (27) has the shape of a convex arc line as viewed in planar view toward the outside, more precisely an arc line the crest (36) of which is facing forward. In such a way, the position of the contact of the support pad with a hole wall can be predetermined in an exact way. In another aspect, the invention also relates to a drill body equipped with one or more support pads.