Spring Coupling for Screw Gear Blocking Torque Cushioning

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Solution Overview

Problem

Machine tools, such as pipe presses, face mechanical stress and potential damage due to high forces, torque, and current loads when the threaded spindle drive is in fully extended or retracted positions, leading to 'running on block' conditions.

Innovation Solution

Incorporating a coupling device with a sleeve and piston that transmits rotary movement from a gear device to the threaded spindle drive, featuring a spring element, such as a torsion bar spring, to absorb torsional forces and reduce mechanical stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the threaded spindle drive is operated in fully extended or retracted positions, then the machine tool can achieve maximum stroke range, but high mechanical stress and torque lead to blocking and potential damage

Engineering Contradiction:
Improvestroke rangeVSAvoidmechanical stress resistance
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The spring element is pre-installed in the coupling device to provide cushioning before the blocking condition occurs. When the threaded spindle drive approaches extreme positions, the spring element is compressed or extended to absorb the increasing torsional forces, preventing the high mechanical stress from directly transmitting to the motor and gearbox components.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The spring element acts as an intermediary component between the coupling device and the threaded spindle drive. It mediates the torque transmission by providing a compliant connection that can deform elastically under high torsional loads, thereby protecting the motor and gearbox from direct exposure to blocking forces while still enabling the full stroke range.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If a rigid coupling device is used to transmit torque directly, then the structure is simple and strong, but high torsional forces cause blocking and damage to motor and gearbox

Engineering Contradiction:
Improvestructural strengthVSAvoidtorsional stress
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The coupling device changes its mechanical parameter (stiffness) by incorporating a spring element that can deform elastically. This allows the coupling to remain structurally strong while dynamically adjusting its torsional stiffness based on the operating conditions, thereby reducing peak torsional stresses during blocking conditions without compromising overall structural integrity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The coupling device transitions from a static rigid connection to a dynamic compliant connection through the spring element. The spring allows the coupling to adapt its characteristics during operation, providing flexibility when needed to absorb torsional shocks while maintaining structural strength during normal operation.

Inventive Principle:
Principle #15Dynamics

3Reliability

If the motor is dimensioned larger to handle blocking current, then the machine tool can withstand extreme positions, but the device complexity and cost increase

Engineering Contradiction:
Improveblocking current resistanceVSAvoidmotor sizing
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The spring element provides beforehand cushioning by absorbing torsional forces before they reach the motor during blocking conditions. This allows the motor to be dimensioned for normal operating conditions rather than extreme blocking scenarios, reducing motor size and complexity while still protecting the system from damage through the spring's mechanical cushioning action.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 spring element effectively mitigates torsional forces during extreme positions of the threaded spindle drive, reducing the risk of damage and enhancing operational safety and efficiency by distributing torque and reducing peak loads on motor and gearbox components.

Implementation Method 1

at least one spring element is included for reducing a torsion acting on the coupling device

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4251903B1Spring element on coupling device
Publication Date: 2024.08.14 HILTI AG
  • EP4251903B1 patent drawingFigure 1
  • EP4251903B1 patent drawingFigure 2
  • EP4251903B1 patent drawingFigure 3

AI summary

Disclosed is a machine tool, in particular a tube extrusion press, comprising a drive, a transmission device, a screw gear and a linear actuator, wherein a torque generated by the drive can be transmitted to the linear actuator via the transmission device, the screw gear. The machine tool includes a coupling device for transmitting, from the transmission device to the screw gear, a rotation that is generated by the transmission device and converted into a linear movement to be transmitted to the screw gear, wherein at least one spring element is provided for reducing torsion acting on the the coupling device.