Boring Bar Chip Pocket Segmentation for Stiffness and Discharge
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Solution Overview
Problem
Cutting tools for boring struggle to efficiently remove chips from small-diameter and deep holes, leading to chip sticking and surface roughness issues due to insufficient chip pocket capacity and stiffness, particularly in external oil supply systems.
Innovation Solution
A cutting tool design featuring a cutting surface-sided chip pocket and a cutting edge-sided chip pocket formed adjacent to each other, with a chamfered intersection, to create a larger discharging route and prevent chip sticking, while maintaining holder stiffness through strategic positioning and shape configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the holder is thinned to improve chip removal, then chip discharge efficiency is improved, but holder stiffness decreases causing chatter vibration
Solution Approach 1:
The holder is divided into multiple functional zones: a thinned portion (first portion) for chip removal and a thicker portion (second portion) for maintaining stiffness. This segmentation allows each zone to fulfill its specific function without compromising the overall structural integrity of the holder.
Solution Approach 2:
The holder exhibits non-uniform cross-sectional area along its length, with the front end being thinner to facilitate chip discharge and the rear end being thicker to provide structural support. This local variation in geometry optimizes both chip removal efficiency and holder stiffness in different regions.
2Volume of stationary object
If a single chip pocket is formed to improve chip capacity, then chip storage space is increased, but chip discharge efficiency deteriorates due to congestion
Solution Approach 1:
The chip pocket is divided into multiple sub-pockets (first sub-pocket and second sub-pocket) that are spatially separated. This segmentation creates multiple independent discharge paths, preventing chip congestion and improving overall discharge efficiency while maintaining adequate chip storage capacity.
Solution Approach 2:
The chip pockets are arranged in different circumferential positions around the holder, utilizing the radial dimension. This spatial distribution in multiple dimensions allows chips to be discharged through different routes simultaneously, avoiding congestion that would occur with a single centralized pocket.
3Manufacturing precision
If the cutting edge protrusion amount is increased to improve cutting performance, then machining capability is improved, but chip removal becomes more difficult due to reduced gap
Solution Approach 1:
The holder is segmented into a thinned front portion and a thicker rear portion, allowing the cutting edge to protrude sufficiently for effective cutting while the thinned section maintains an adequate gap for chip removal. This segmentation decouples the conflicting requirements of cutting performance and chip discharge.
Solution Approach 2:
The holder has different geometric properties at different locations: the front end has a larger gap between the outer circumferential surface and the inner circumferential surface of the workpiece to facilitate chip removal, while the rear end has sufficient thickness for structural support. This local quality variation resolves the contradiction between cutting edge protrusion and chip removal gap.
Data Source
AI summary
A cutting tool for boring including a cutting insert fixed at a front end of a bar-shaped holder. The holder includes a cutting surface-sided chip pocket that is concave with respect to the outer circumferential surface of the holder, the cutting edge end of the cutting insert protruding from the outer circumferential surface of the holder, and the cutting surface-sided chip pocket having a bottom surface facing the portion of outer circumferential surface where the cutting edge overhangs. Further, an cutting edge-sided chip pocket is formed at the portion of outer circumferential surface where the cutting edge overhangs such that the edge of the portion of outer circumferential surface where the cutting edge overhangs is concave with respect to the outer circumferential surface of the holder, on the bottom of the cutting surface-sided chip pocket when viewed from the cutting surface.