Boring Bar Torque Measurement via Torsion Angle

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Solution Overview

Problem

Existing boring machine tools lack precise measurement of twisting moment or torque applied to the boring bar, leading to imprecise machining and inability to adjust machining parameters retroactively to maintain desired torque values.

Innovation Solution

A measuring device comprising a tubular element inserted into the boring bar with sensor means to detect torsion angles between the machining tool end and the coupling zone, processing signals to calculate the twisting moment using a computing unit, allowing for precise torque measurement and adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If current absorption by the motor is used to detect torque, then torque measurement is possible, but measurement precision deteriorates

Engineering Contradiction:
Improvetorque measurement precisionVSAvoidmeasurement device structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces electrical measurement methods (current absorption) with a mechanical measurement system. A tubular element is inserted into the boring bar to directly measure torsion angle mechanically, providing more precise torque measurement without relying on indirect electrical measurements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a tubular element as an intermediary component inserted into the boring bar. This intermediary element directly experiences the torsion and allows for precise measurement of the torsion angle, serving as a mediator between the torque application and the measurement system.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If torque measurement is implemented, then machining parameter adjustment is possible, but device complexity increases

Engineering Contradiction:
Improvemachining precisionVSAvoidmeasuring device structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The tubular element serves multiple functions: it structurally reinforces the boring bar while simultaneously acting as a measurement component for torsion angle detection. This multi-functionality reduces the need for additional separate components, managing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The tubular element is nested within the boring bar structure, utilizing the existing hollow space of the boring bar. This nesting approach integrates the measurement function into the existing structure without adding significant external complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Measurement precision

If transmission means are positioned near the second end of the boring bar, then torsion angle increases, but torque measurement accuracy deteriorates

Engineering Contradiction:
Improvetorsion angle measurementVSAvoidtransmission means positioning
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent makes the measurement system dynamic by allowing the tubular element to freely rotate within the boring bar while maintaining measurement capability. This dynamic configuration allows the system to adapt to different transmission means positions along the boring bar.

Inventive Principle:
Principle #15Dynamics

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

Enables precise measurement and adjustment of torque applied to the boring bar, ensuring high precision and accuracy in machining operations by determining the torsion angle and calculating the actual twisting moment, thereby correcting machining parameters in real-time.

Implementation Method 1

The torque and the resistant torque generate torsional stress on and along the boring bar and determine a angular rotation (torsion angle) of the bar sections with respect to a neutral longitudinal axis of the bar

Methodology Applied
Scientific EffectTorsion: Torque

Data Source

PatentEP2615438B1Torque measuring device for boring machine
Publication Date: 2015.03.25 PAMA SPA
  • EP2615438B1 patent drawingFigure 1
  • EP2615438B1 patent drawingFigure 2~4
  • EP2615438B1 patent drawing

AI summary

A measuring device for a boring machine tool that comprises a boring bar (2), that is movable along and around a working axis (Z) and provided with a first end (3) that is suitable for supporting a machining tool, and a spindle (5) for slidably supporting the boring bar (2) and transmitting torque thereto at a coupling zone (7), a first portion (21) of the boring bar (2) comprised between the first end (3) and the coupling zone (7) being subject to torque, the measuring device (1) comprising: - a tubular element (9) inserted into the boring bar (2) and provided with a first end part (10) fixed to the first end (3) in such a manner that the tubular element (9) rotates together with the latter; - first sensor means (12) associated with the tubular element (9) to detect a first signal (S1) indicating rotation of the tubular element (9) and thus of the first end (3); - second sensor means (13) associated with a second portion (22) of the boring bar (2) not subject to torque to detect a second signal (S2) indicating a rotation of the boring bar (2) in the second portion (22); and - a computing unit (17) for receiving and processing the first signal (S1) and the second signal (S2) and calculating an angular displacement (Δθ) between the first end (3) and the second portion (22), the angular displacement (Δθ) being a torque angle to which the first portion (21) is subject.