Threaded Spindle Drive Stops for Low-Friction Mobile Press Tools

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Solution Overview

Problem

Existing mobile machine tools face challenges in achieving high pressing force, energy efficiency, high-speed linear movement, compact size, low manufacturing costs, and economic operation while maintaining high performance and productivity.

Innovation Solution

A mobile machine tool design featuring a drive, threaded spindle, and linear actuator, where a rotary movement is converted into a linear movement through an intermediate part with bearing elements, such as rollers or balls, to reduce friction and enhance support, while a stop limits the movement area to ensure permanent functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a threaded spindle drive is used to generate high pressing force, then the load capacity is improved, but friction between the inner and outer lead screw sections increases

Engineering Contradiction:
Improvepressing forceVSAvoidfriction
Core Design Contradiction:
ForceVSLoss of energy

Solution Approach 1:

An intermediate part with bearing elements (balls or rollers) is introduced between the inner and outer threaded spindle parts. This intermediary component reduces friction by enabling the inner threaded spindle part to move relative to the outer part through rolling or ball bearing contact, while still transmitting the necessary forces and torques to generate high pressing force at the tool head.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If the intermediate part is allowed to move freely to reduce friction, then energy efficiency is improved, but the intermediate part may shift out of position causing permanent damage

Engineering Contradiction:
ImprovefrictionVSAvoidposition stability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

Stops are pre-positioned on the outer threaded spindle part at predetermined locations along the longitudinal axis. These stops limit the range of motion of the intermediate part before any damaging displacement can occur. The stops are strategically placed to allow the intermediate part sufficient movement to reduce friction during operation, while preventing it from shifting out of the threaded engagement entirely.

Inventive Principle:
Principle #10Preliminary action

3Loss of energy

If bearing elements are used to reduce friction, then energy efficiency is improved, but manufacturing costs increase

Engineering Contradiction:
ImprovefrictionVSAvoidmanufacturing cost
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent employs simple bearing elements such as balls or rollers that can be easily manufactured and replaced. These bearing elements are designed to be cost-effective and simple in structure, allowing for economical production while still achieving the goal of reducing friction. The intermediate part with its bearing elements can be manufactured at low cost and replaced if necessary, making the system economically viable.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Volume of moving object

If the machine tool is made compact to work in confined spaces, then adaptability is improved, but the threaded spindle drive may lack sufficient stroke length

Engineering Contradiction:
Improvemachine tool sizeVSAvoidspindle stroke length
Core Design Contradiction:
Volume of moving objectVSLength of moving object

Solution Approach 1:

The intermediate part is designed to move dynamically along the longitudinal axis within the threaded spindle drive, enabled by the stops that define its range of motion. This dynamic movement allows the intermediate part to traverse a sufficient distance to provide an adequate stroke length for the linear actuator, while the entire threaded spindle drive assembly remains compact enough to be integrated into a portable machine tool for work in confined spaces.

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

The solution enables the machine tool to achieve high pressing forces, efficient energy use, rapid linear movement, compact size, and low manufacturing costs, thereby enhancing productivity and operational economics while maintaining high performance.

Implementation Method 1

The intermediate part can have individual elements through which forces and/or torques can be transmitted between the inner and outer threaded sections. The individual elements can be movably accommodated in the intermediate part. The individual elements can protrude into the internal and/or external thread. The individual elements can be, for example, bearing balls and/or bearing rollers.

Methodology Applied
Scientific EffectFriction reduction through bearing elements: Ball Bearing

Implementation Method 2

a rotary movement generated by the drive can be converted via the threaded spindle drive into a linear movement of the linear actuator along a longitudinal axis of the threaded spindle drive

Methodology Applied
Scientific EffectThreaded spindle mechanical advantage: Screw

Data Source

PatentEP4530021A1Mobile machine tool with a threaded spindle drive comprising a stop
Publication Date: 2025.04.02 HILTI AG
  • EP4530021A1 patent drawingFigure 1
  • EP4530021A1 patent drawingFigure 2
  • EP4530021A1 patent drawingFigure 3

AI summary

The invention relates to a mobile machine tool (10), in particular a pressing, crimping and/or cutting machine, comprising a drive (24), a threaded spindle drive (28) and a linear actuator (30), wherein a rotary movement generated by the drive (24) can be converted via the threaded spindle drive (28) into a linear movement of the linear actuator (30) along a longitudinal axis (L) of the threaded spindle drive (28), wherein the threaded spindle drive (28) has an inner threaded spindle part (38) with an external thread (40) and an outer threaded spindle part (42) with an internal thread (44), wherein the outer and the inner threaded spindle parts (38, 42) interact via an intermediate part (46) arranged between the two threaded spindle parts (38, 42), wherein the threaded spindle drive (28) has at least one stop (48, 50) by which a movement range (B) of the The intermediate part (46) is limited at least on one side along the longitudinal axis (L).The mobile machine tool (10) is inexpensive to manufacture and particularly efficient.