Piezoelectric Brake Bench for High-Speed Screwdriver Testing

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Solution Overview

Problem

Current hydraulic braking systems in test benches for industrial screwdrivers are limited by their slow frequency response, restricting the minimum braking duration time and maximum rotation speed that can be tested, due to their restricted bandwidth, which is typically below 100 Hz.

Innovation Solution

The use of piezoelectric actuators with a much faster frequency response (around 10 KHz) replaces traditional hydraulic brakes, enabling more precise and rapid modulation of braking capacity through the inverse piezoelectric effect, where electrical energy is converted into mechanical forces and movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If hydraulic brakes are used in the test bench, then large amounts of energy can be transferred, but the frequency response is slow (bandwidth below 100 Hz)

Engineering Contradiction:

Improveenergy transfer capabilityVSAvoidfrequency response

Core Design Contradiction:

PowerVSSpeed

Solution Approach 1:

The patent replaces the hydraulic actuation system with a piezoelectric actuation system. The piezoelectric actuator converts electrical energy directly into mechanical displacement, eliminating the need for hydraulic fluid and mechanical linkages. This substitution enables a frequency response in the order of 10 KHz while maintaining the ability to transfer large amounts of energy, thus resolving the contradiction between power capability and speed of response.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If hydraulic actuation system is used, then braking capacity can be controlled, but the minimum braking duration time is limited due to restricted bandwidth

Engineering Contradiction:

Improvebraking capacity controlVSAvoidminimum braking duration time

Core Design Contradiction:

Ease of operationVSDuration of action of moving object

Solution Approach 1:

The piezoelectric actuator replaces the hydraulic actuation system, enabling precise control of braking capacity through electrical signals. The piezoelectric material responds almost instantaneously to voltage changes, allowing the braking capacity to be modulated with minimum braking duration times in the order of microseconds, thus resolving the contradiction between ease of control and minimum action duration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If hydraulic brakes are used, then the system can simulate tightening processes, but the maximum rotation speed that can be tested is limited

Engineering Contradiction:

Improvetightening process simulationVSAvoidmaximum rotation speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent replaces the hydraulic brake system with a piezoelectric actuator that can rapidly modulate braking force. This enables the test bench to accurately simulate tightening processes while accommodating much higher rotation speeds, as the piezoelectric actuator can respond to the rapid changes in torque and speed characteristics of modern high-speed screwdrivers, thus resolving the contradiction between simulation accuracy and maximum testable speed.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This solution allows for higher rotation speeds and more precise testing of screwdrivers by overcoming the bandwidth limitations of hydraulic systems, enabling faster and more accurate simulation of tightening processes.

Implementation Method 1

The use of piezoelectric actuators with a much faster frequency response (around 10 KHz), enabling more precise and rapid modulation of braking capacity through the inverse piezoelectric effect, where electrical energy is converted into mechanical forces and movements.

Methodology Applied

Scientific EffectInverse piezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3899467B1Braking device positionable on test benches of correct operation of industrial screwdrivers

Publication Date: 2024.06.05 ATLAS COPCO IND TECHNIQUE AB INTELLECTUAL PROPERTY DEPARTMENT

Figure 1~2
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Figure 5~6

AI summary

Braking device inserted in a test bench (2) for checking the correct operation of industrial screwdrivers, wherein the braking simulates a tightening operation of such screwdriver, comprising a container body (1) on the top of which a coupling (11) protrudes, suitable for coupling with the head (3) of the screwdriver to be tested, said coupling (11) being connected, by means of a shaft (12), to a braking unit (13), an electronic torque and angle detector (14) of the shaft rotation (12). Such braking unit (13) comprises a plate (14), rotated by the screwdriver, which is braked by suitable friction surfaces (15) moved towards the plate by the movement of an actuator; the movement of such actuator is performed by means of at least one electronically controlled piezoelectric element (17).