Gear Rack Drive for High-Precision Workpiece Transfer

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Solution Overview

Problem

Existing workpiece transfer devices lack high precision and accuracy in positioning workpieces, often due to mechanical inaccuracies such as play and elongation in roller chains or push chains, which are also costly.

Innovation Solution

A workpiece transfer device utilizing a gear drive system with a motor-side gear element and a drive rack, where the gear elements are engaged perpendicular to the transport direction via a lifting device, establishing a precise drive connection between the drive gear and the workpiece carrier, allowing for high-precision movement without the need for the drive motor on the carrier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If roller chains or push chains are used to drive the workpiece carrier, then the device complexity is reduced and cost is lowered, but positioning accuracy deteriorates due to mechanical play and elongation

Engineering Contradiction:
Improvepositioning accuracyVSAvoiddrive system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the traditional chain drive system with a gear rack and pinion gear system. The drive gear (24) engages with the drive rack (20) to provide positive mechanical engagement that eliminates the play and elongation problems inherent in chain drives, thereby achieving high positioning accuracy while maintaining relatively simple device complexity

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

Solution Approach 2:

The patent introduces a vertical dimension (perpendicular to the transport direction) by using a lifting device (25) to move the workpiece carrier vertically. This allows the drive gear and drive rack to engage in the vertical dimension while the workpiece carrier moves horizontally, separating the engagement dimension from the transport dimension and enabling precise positioning without compromising the simplicity of the horizontal transport mechanism

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If a drive motor is mounted on the workpiece carrier, then positioning precision is improved through direct control, but the weight of the moving object increases

Engineering Contradiction:
Improvepositioning precisionVSAvoidworkpiece carrier weight
Core Design Contradiction:
Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The patent extracts the drive motor from the workpiece carrier and mounts it on the stationary support structure instead. The drive motor (15) is now part of the stationary drive system, connected to the drive gear (24) that engages the drive rack (20) on the workpiece carrier. This removes the heavy motor weight from the moving carrier while maintaining precise control through the gear rack and pinion mechanism

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If the drive gear and drive rack are engaged perpendicular to the transport direction via lifting device, then positioning accuracy is improved, but the device complexity increases due to additional lifting mechanism

Engineering Contradiction:
Improvedrive connection precisionVSAvoidengagement mechanism complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses the vertical dimension (perpendicular to horizontal transport) to achieve gear engagement. The lifting device (25) moves the workpiece carrier vertically to engage or disengage the drive rack (20) with the drive gear (24). This dimensional separation allows precise drive connection without complicating the horizontal transport mechanism, as the engagement and transport occur in different dimensions

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 gear drive system provides high positioning accuracy and cost-effectiveness by eliminating the need for a drive motor on the workpiece carrier, enabling precise movement of workpieces into and out of the machine tool's work area while extending the workpiece carrier's travel distance through offset drive gears.

Implementation Method 1

the gear arranged between the drive motor and the workpiece carrier is a motor-side gear element that can be driven by the drive motor in the form of a gear element on the motor side that runs perpendicular to the transport direction by means of the drive motor Gear axle drivable drive gear as well as a further gear element designed as a drive rack running in the transport direction

Methodology Applied
Scientific EffectGear mechanism: Gear

Implementation Method 2

one gear element of the drive gear and the drive rack connected to the workpiece carrier and thereby connected to the workpiece carrier and by means of the drive motor jointly with the workpiece carrier relative to the other gear element is drivable in the transport direction

Methodology Applied
Scientific EffectRack and pinion: Rack and Pinion

Data Source

PatentEP3156175B1Workpiece transfer device and machine tool with a workpiece transfer device
Publication Date: 2019.03.20 TRUMPF SACHSEN GMBH
  • EP3156175B1 patent drawingFigure 1~2
  • EP3156175B1 patent drawingFigure 3~4

AI summary

A workpiece transfer device (4) comprises a workpiece carrier (5, 6) and a motor drive (14) by means of which the workpiece carrier (5, 6) can be moved in a transport direction (13) from a starting position to a target position. The motor drive (14) has a drive motor (15) and a gearbox (18, 19) arranged between the drive motor (15) and the workpiece carrier (5, 6). A motor-side gear element of the gearbox (18, 19) is designed as a drive gear (17) and can be driven by the drive motor (15) about a gear axis extending perpendicular to the transport direction (13). A drive rack (20, 21) extending in the transport direction (13) is provided as a further gear element. Either the drive gear (14) or the drive rack (20, 21) is connected to the workpiece carrier (5, 6).With a coupling stroke executed perpendicular to the transport direction (13), the drive gear (17) and the drive rack (20, 21) can be moved relative to each other and thereby brought into engagement, as a result of which the gear element connected to the workpiece carrier (5, 6) can be driven together with the workpiece carrier (5, 6) by means of the drive motor (15) in the transport direction (13). A machine tool (1) comprises a workpiece transfer device (4) of the above type.