Undercut drill bit with mechanically activated cutting mechanism

Abstract

Drilling tool for producing a stepped borehole with an upper section of the first diameter and a lower section of the larger diameter, characterized in that the tool has a mechanically activatable cutting mechanism which is arranged in the lower part of the tool and is activated by contact with the borehole base, wherein the cutting mechanism consists of at least two radially extendable cutting elements which are brought from their rest position into a cutting position by a central activator.

Description

1. Technical field

[0001] The invention relates to a drilling tool for producing stepped boreholes with different diameters, particularly for use in materials such as metal, concrete, and plastic. The tool enables the targeted enlargement of the lower hole section (undercut) by means of a mechanically activated cutting mechanism, without damaging the upper section. 2. State of the art

[0002] Conventional drills produce either cylindrical holes with a constant diameter or stepped holes through sequential machining with multiple tools. For undercut applications, the following currently exist: • Zykon drills (e.g. Fischer FZUB) that create conical undercuts, but are not reversible or mechanically controllable. • Internal machining tools on lathes that create undercuts through radial deflection, but are not suitable for mobile or manual applications. • Step drills that create larger diameters from top to bottom, but do not allow for targeted enlargement of the lower section. • A tool that allows for a targeted, mechanically activated extension of the lower drill section does not exist in the prior art. 3. Object of the invention

[0003] The aim of the invention is to provide a drilling tool that: • creates a precise undercut geometry, • leaves the upper section of the borehole intact, • can be mechanically activated and deactivated, • suitable for various materials and applications • Easy handling without additional machines is allowed. 4. Solution

[0004] The invention comprises a drill bit with the following features: • Cylindrical guide body with a diameter corresponding to the upper drill section (e.g. Ø6 mm). • Mechanically activated cutting mechanism in the lower area, consisting of: • Two symmetrically arranged cutting arms (L-shape or balls Ø3 mm), • A central activator (pyramidal or romboidal) which deflects the cutting elements radially upon contact with the borehole base, • A reset mechanism that returns the cutting elements to their starting position through axial pressure. • Drilling depth control via integrated stops or guide sleeves. 5. Advantages of the invention • Precise geometry: The undercut is specifically targeted in the lower area. • Material protection: The upper section of the drill remains undamaged. • Mechanical control: No electronics or external power source required. • Multi-material capability: Suitable for metal, concrete, plastic. • Scalability: The diameter and depth of the undercut are adjustable. • Reusability: The mechanism is reversible and durable. 6. Areas of application • Construction industry: Anchoring systems in concrete and masonry. • Mechanical engineering: Assembly of components with a positive-locking connection. • Medical technology: Precise drilling in implants or instruments. • Electronics: Housing mounting with concealed anchors. • Aerospace: Structural connections with controlled loading. 7. Industrial Application - Defense Technology • The drilling tool is particularly suitable for the production of precise combustion chambers in ballistic systems. • The undercut geometry allows chambers for propellant charges to be inserted directly into weapon tubes. • Applications in the defense industry include the manufacturing of modular artillery systems, ballistic test platforms, and automated ammunition systems. • The ability to precisely control the chamber geometry allows for flexible design of range, projectile type and energy transfer. • The tool contributes to the reduction of weight, material consumption and reloading time and is compatible with modern manufacturing processes. 8. Scaling and Variants

[0005] The tool can be manufactured in various sizes and designs: • Diameter range: Ø4 mm to Ø12 mm • Undercut depth: 5 mm to 20 mm • Cutting elements: balls, flaps, sliders • Materials: HSS, cemented carbide, titanium alloys 9. Quality characteristics • High dimensional accuracy (<0.1 mm tolerance) • Corrosion-resistant materials • Low-wear cutting surfaces • Easy cleaning and maintenance

Claims

[1] Drilling tool for producing a stepped borehole with an upper section of the first diameter and a lower section of the larger diameter, characterized by that the tool has a mechanically activatable cutting mechanism located in the lower part of the tool and activated by contact with the borehole base, wherein the cutting mechanism consists of at least two radially extendable cutting elements which are brought from their rest position into a cutting position by a central activator. [2] Drilling tool according to claim 1, characterized by , that the cutting mechanism can be deactivated by axial pressure or impact, whereby the cutting elements are returned to their starting position by spring force, gravity or mechanical guidance. [3] Drilling tool according to claim 1 or 2, characterized by, that the cutting mechanism can be controlled by the direction of rotation of the tool, whereby in clockwise rotation a control bolt is screwed in, which extends the cutting elements, and in counterclockwise rotation the bolt is unscrewed, thereby retracting and locking the cutting elements. [4] Drilling tool according to any one of the preceding claims, characterized by , that the cutting mechanism is modular and includes interchangeable cutting elements, the cutting elements of which can be designed as balls, flaps, knives or sliders. [5] Drilling tool according to any one of the preceding claims, characterized by that the tool is suitable for processing metal, concrete and plastic and is made of corrosion-resistant and low-wear materials. [6] Drilling tool according to any one of the preceding claims, characterized by, that the first diameter is between 4 mm and 12 mm and the depth of the undercut is variable between 5 mm and 20 mm. [7] Drilling tool according to any one of the preceding claims, characterized by that the tool has an integrated depth stop or guide sleeve that limits the activation of the cutting mechanism to a defined depth. [8] Drilling tool according to any one of the preceding claims, characterized by , that it is used for the manufacture of combustion chambers in ballistic or defense systems, in particular for the production of undercut geometries for modular projectile and propellant charge units. [9] Drilling tool according to claim 8, characterized by , that the combustion chamber created by the tool has a larger diameter than the subsequent gun barrel bore, with the projectile resting directly against the chamber opening and being inserted without a sleeve. [10] Drilling tool according to one of claims 8 to 9, characterized by , that the geometry of the combustion chamber can be adjusted by selecting the undercut diameter and depth to vary the range, impulse and projectile type.

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