Machine Tool Clamping Chuck With Belt-Coupled Fail-Safe Drive

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Solution Overview

Problem

Existing clamping devices for machine tools lack a reliable energy storage mechanism to maintain clamping force, leading to high control and construction costs, susceptibility to faults, and the need for complex controls and oil baths, which increases the risk of accidents and energy consumption.

Innovation Solution

The clamping device employs belt drives with a servo device and energy accumulator, using a support hub with axially displaceable intermediate members and toothed pulleys to ensure secure coupling and automatic blocking in case of failures, allowing for low-cost, fault-resistant operation without oil baths and complex controls.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gear sets are used in the drive train, then reliable power transmission is achieved, but the device requires oil baths and complex control systems, increasing construction costs and susceptibility to faults

Engineering Contradiction:
Improvereliable power transmissionVSAvoidcomplex control systems and oil baths
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical gear set system with a belt drive system. The drive train consists of a drive belt and two pulleys (first and second pulleys) that transmit power without requiring oil baths or complex control systems. This substitution eliminates the need for lubrication systems and reduces mechanical complexity while maintaining reliable power transmission from the drive motor to the motion converter.

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

Solution Approach 2:

The patent extracts and removes the gear sets and their associated oil bath systems from the drive train. By eliminating these components entirely and using only belt drives, the invention reduces construction costs and susceptibility to faults related to lubrication system failures and complex gear control mechanisms.

Inventive Principle:
Principle #2Taking out (Extraction)

2Adaptability or versatility

If electric clutches are used to switch between drive trains, then drive switching is achieved, but the switching effort is very high and control capacity requirements increase

Engineering Contradiction:
Improvedrive switching capabilityVSAvoidhigh control capacity requirements
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a dynamic belt tensioning system where the tensioning device can adjust the tension of the drive belt. The tensioning device includes a tensioning pulley and a servo device that can actively control the belt tension and switch between different drive modes (first and second drive trains) without requiring electric clutches. This dynamic adjustment mechanism reduces control complexity by using mechanical tension variation instead of complex clutch switching.

Inventive Principle:
Principle #15Dynamics

3Power

If the drive motor remains connected during operation, then continuous power availability is ensured, but energy consumption increases

Engineering Contradiction:
Improvecontinuous power availabilityVSAvoidenergy consumption
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic connection and disconnection of the drive motor to the drive train. The tensioning device can selectively engage or disengage the drive belt from the pulleys based on operational requirements. When clamping or unclamping operations are not needed, the drive motor can be decoupled from the drive train, reducing energy consumption while maintaining the capability to quickly re-engage power when needed.

Inventive Principle:
Principle #19Periodic action

4Device complexity

If no energy store is provided, then the structure is simpler, but the clamping force cannot be maintained without continuous power

Engineering Contradiction:
Improvesimpler structureVSAvoidcontinuous power requirement
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent incorporates an energy store (spring element) that is pre-loaded during the clamping operation. The spring accumulates potential energy when compressed by the drawbar movement, and then maintains the clamping force on the workpiece after the drive motor has completed its operation. This preliminary energy storage allows the clamping force to be maintained without continuous power supply, reducing energy consumption while keeping the structural complexity relatively low.

Inventive Principle:
Principle #10Preliminary action

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 design ensures safe, trouble-free operation over a long period with reduced energy consumption and manufacturing costs, as it automatically blocks in case of failures and decouples the drive motor during operation, eliminating the need for complex controls and oil baths.

Implementation Method 1

an energy accumulator for maintaining the clamping force

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP3127640B1Clamping device
Publication Date: 2023.02.22 MTH GBR MARKUS & THOMAS HIESTAND
  • EP3127640B1 patent drawingFigure 1
  • EP3127640B1 patent drawingFigure 2
  • EP3127640B1 patent drawingFigure 3

AI summary

In a clamping device (1) for machine tools (2), which is equipped with a power chuck (5) for holding a workpiece (10), an electric drive motor (11) connected to it via two drive trains (21, 31), a motion converter (15), and an energy storage device (16), the drive trains (21, 31) each consist of a first and second belt drive (21', 31'), and a support hub (13) is fixedly arranged on the rotor shaft (12) of the drive motor (11). The pulley (22) of the first belt drive (21') is fixedly mounted on the support hub, and the pulley (32) of the second belt drive (31') is rotatably mounted on the support hub. Furthermore, in the clamping position, the two pulleys (22, 32) can be coupled to each other by means of a servo device (51).In this way it is possible to adapt the drive motor (11) to the respective conditions using an NC control, so that safe and trouble-free operation is ensured over a long period of time with low construction effort and without the need for intermediate gearboxes.