Indexable Ball End Mill With Inclined Threaded Holes
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Solution Overview
Problem
Conventional ball end mills, particularly those with fewer flutes, face challenges in high-speed and high-precision cutting due to inadequate positioning precision and durability, leading to insufficient cutting efficiency and efficiency in machining die cavities.
Innovation Solution
A four-flute indexable ball end mill design featuring a semispherical tip end portion with inclined threaded holes and inserts, where the first insert's hole and screw have specific surface roughness and dimensions to ensure precise positioning and avoid interference with other screws, allowing for high-precision and efficient cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fixing methods (screws and pressing plates) are used for cutting chips, then the tool can be assembled, but the cutting chips may be detached during high-speed cutting due to insufficient fixing strength and positioning precision
Solution Approach 1:
The tool body is divided into multiple seats (first seat, second seat, third seat) that can independently hold different cutting chips. Each seat has its own threaded hole for fixing, allowing separate assembly and replacement of cutting chips without affecting other parts. This segmentation enables reliable fixing of each cutting chip while maintaining overall structural simplicity.
Solution Approach 2:
The threaded holes are pre-formed in the tool body at specific locations and angles before assembly. The first threaded hole is inclined at a predetermined angle θ, and the second and third threaded holes are positioned to avoid interference. This preliminary preparation ensures that cutting chips can be securely fixed without requiring complex adjustment mechanisms during operation.
2Ease of operation
If positioning is achieved by contact between circular notch and sphere, then assembly is simple, but positioning precision is insufficient due to dimensional precision limitations of the circular notch and sphere
Solution Approach 1:
The invention replaces the contact-based positioning system (circular notch and sphere) with a threaded fastening system. The screws engage with threaded holes in the tool body and pressing surfaces on the cutting chips, providing precise positioning through thread engagement rather than point contact. This mechanical substitution achieves both ease of assembly and high positioning precision.
Solution Approach 2:
The invention changes the positioning parameters from geometric contact (circular notch diameter and sphere diameter) to threaded engagement parameters (thread pitch, thread depth, pressing surface position). This parameter change allows for more precise control of cutting chip position through the threaded connection, achieving positioning precision limited only by thread manufacturing tolerances rather than contact surface tolerances.
3Device complexity
If a 2-flute design is used, then the tool structure is simpler, but cutting efficiency is insufficient for high-speed machining of die cavities
Solution Approach 1:
The tool body is segmented into four distinct cutting edges arranged in a multi-flute configuration. The first seat holds one cutting chip, while the second and third seats hold additional cutting chips that contribute to the four-flute design. This segmentation increases the number of active cutting edges, thereby improving cutting efficiency and productivity for high-speed machining operations.
4Ease of manufacture
If threaded holes are arranged without inclination, then manufacturing is simpler, but interference occurs between screws for different inserts
Solution Approach 1:
The first threaded hole is designed with an inclination angle θ relative to the tool axis, creating an asymmetric arrangement. This asymmetric positioning of the first threaded hole, combined with the specific positioning of the second and third threaded holes, eliminates interference between screws while maintaining manufacturability. The asymmetric design allows all screws to be installed without collision.
5Adaptability or versatility
If conventional ball end mills are used, then the tool can perform basic cutting, but positioning precision and durability are insufficient for high-precision finishing operations
Solution Approach 1:
The threaded holes are pre-formed with precise geometry and orientation before cutting chip installation. The pressing surfaces on the cutting chips are also pre-prepared with appropriate flatness and position. This preliminary preparation ensures that when the cutting chips are installed and tightened, they achieve high positioning precision immediately, suitable for high-precision finishing operations.
Solution Approach 2:
The invention replaces the conventional single-piece ball end mill structure with a modular system using replaceable cutting chips held by threaded fasteners. This mechanical substitution allows for precise positioning of each cutting chip through the threaded connection system, improving both positioning precision and durability compared to conventional integrated designs.
Data Source
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AI summary
. An indexable ball end mill comprising first to third inserts having arcuate cutting edges detachably attached with first to third screws to first to third seats in a semispherical tip end portion of a tool body; a first threaded hole for the first screw slantingly penetrating a slit-shaped first seat; the first insert having an inclined hole to avoid interference between the first screw and the second and third screws; a hole of the first insert and the first screw having at least partially finished surfaces, so that when the first screw penetrates the first insert attached to the first seat, the first insert is precisely positioned by tight engagement of both finished surfaces.