Reaming Tool Unit With Elastic Centering and High-Pressure Cooling

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Solution Overview

Problem

Current CNC machine tool units fail to consistently achieve the required precision and flexibility for reaming holes of 3 to 32 mm in diameter and up to 120 mm depth with IT5 accuracy, leading to production losses and increased costs due to imbalances, unreliable centering, and lack of radial and swinging flexibility.

Innovation Solution

A tool unit design featuring a clamping body with a cylindrical cavity and a drive element that includes a flexible disc spring or helical spring for axial play, a structural steel working tool with a sintered carbide cutting part, and continuous channels for cooling medium distribution, allowing for precise positioning and radial movement of the cutting part.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional clamping tools (Weldon, Whistle-Notch, Collet chucks) are used to clamp the working tool, then the tool can be securely held in the spindle, but the tool unit fails to achieve reliable reproducibility of high-precision tool centering and lacks radial and swinging flexibility

Engineering Contradiction:
Improvetool centering accuracy and hole reaming precisionVSAvoidradial and swinging flexibility of the working tool
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The clamping tool employs elastic deformation of its clamping elements (such as spring-loaded fingers or resilient jaws) to achieve both precise centering and radial flexibility. By changing the mechanical parameter of the clamping elements from rigid to elastic, the system can adapt to slight misalignments while maintaining IT5-IT6 accuracy through controlled compliance rather than rigid constraint

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The clamping mechanism transitions from a static, rigid grip to a dynamic system where clamping elements can elastically deform and adjust during operation. This dynamic capability allows the tool to accommodate radial and swinging movements while maintaining precise centering, resolving the contradiction between rigidity for accuracy and flexibility for adaptation

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If rigid clamping mechanisms are used to ensure tool stability, then the tool maintains fixed position, but the tool unit cannot achieve the required radial and swinging flexibility for precise reaming

Engineering Contradiction:
Improvetool position stability in spindleVSAvoidradial and swinging flexibility of working tool
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The clamping elements are designed with elastic properties that allow controlled deformation under load. This parameter change from rigid to elastic enables the system to maintain stability through predictable elastic behavior while simultaneously providing the flexibility needed for radial and swinging adjustments during the reaming process

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Elastic elements act as intermediaries between the rigid spindle and the working tool, absorbing position variations and enabling flexibility while maintaining overall stability. These intermediary components decouple the rigid constraints of the spindle from the tool, allowing controlled movement without compromising positional stability

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If conventional mechanical clamping tools are used, then the structure is simple and affordable, but the tool unit produces large proportions of scrap and requires downtime for re-clamping

Engineering Contradiction:
Improveclamping tool structure simplicityVSAvoidreproducibility of tool centering and service life
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

By changing the mechanical parameter of clamping elements from rigid to elastic, the system achieves self-centering capability that dramatically improves reproducibility of tool centering. This single parameter change transforms a simple mechanical clamp into a reliable self-adjusting mechanism that eliminates the need for frequent re-clamping and reduces scrap

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The elastic clamping elements automatically self-center the tool during the clamping process through their elastic deformation, eliminating the need for complex external centering mechanisms. This self-service capability improves reliability and reduces downtime while maintaining structural simplicity

Inventive Principle:
Principle #25Self-service

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

The tool unit achieves high accuracy, extended service life, and improved durability of cutting tips by ensuring defined flexibility, rigidity, and positional accuracy, reducing production losses and costs through enhanced precision and operational reliability.

Implementation Method 1

a flexible element (7), in this embodiment made as disc springs, which define the axial play of the reaming tool (6)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

continuous channels for cooling medium distribution

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

continuous channels for cooling medium distribution

Methodology Applied
Scientific EffectConduction (thermal): Conduction (thermal)

Data Source

PatentEP3838457B1Tool unit for reaming very precise holes
Publication Date: 2024.07.31 HAM FINAL
  • EP3838457B1 patent drawingFigure 1
  • EP3838457B1 patent drawingFigure 2
  • EP3838457B1 patent drawingFigure 3

AI summary

Tool unit for reaming of very precise holes comprising a clamping body provided with a clamping cylindrical cavity for fixing a tool shank, the main cooling medium channel passing through the shank, where two opposite transverse grooves (23) are formed on the clamping shank (5) of the working tool (6), into which the arms (27) of the horseshoe-shaped drive element (11) the form of which is due to the inner central recess (22), are inserted with their side faces, whereas a transverse groove (21) is formed on the lower face (15) of the clamping body (1) into which the front projections (20) created on the upper surface of the drive element (11) fit, whereas the clamping nut (16) screwed onto the clamping body (1) abuts the lower face of the drive element (11), whereas in the upper part (14) of the clamping cylindrical cavity (4) rests on the face (26) of the cylindrical shank (5) of the reaming tool (6) a spring-loaded distant pin (12) secured by a cap nut (19), above which a flexible element (7) is arranged delimiting the axial play of the working tool (6) and resting from above against the shoulder in the cavity of the clamping body (1), whereas the main channel (8) for guiding the cooling medium is arranged for the pressure of 40-100 bar, from which the cooling pressure medium is distributed to the connecting central channel (9), which mouths in the cutting part (17) of the tool (6) and further into the transverse channel (10), which mouths into the annular cavity (18) between the shank (5) and the cavity (4) of the clamping body (1) and from here further into cylindrical cavity (4).