Sheet Metal Piston Guide for Fuel Setting Tool

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Solution Overview

Problem

The existing combustion-powered setting tools require precise machining of solid bodies for piston guides and driving pistons to ensure a pressure-tight seal, which is costly and time-consuming, and often necessitate complex post-processing steps like honing and deburring.

Innovation Solution

The manufacturing method involves forming a piston guide from a bent sheet metal strip with a seam or toothed connection, allowing for ventilation openings and a textured inner surface that reduces friction and eliminates the need for deburring, using a process that includes punching and cold forming to achieve a pressure-tight seal without complex post-processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If piston guides and driving pistons are machined from solid bodies to ensure precise fit and pressure-tight seal, then sealing reliability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvepressure-tight sealVSAvoidmanufacturing process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The piston guide is manufactured from a sheet metal strip that is bent into a tubular shape and connected by seam or toothed form fit. This flexible shell approach replaces traditional solid body machining while maintaining the pressure-tight seal requirement through the flexibility and conformability of the sheet metal construction.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the manufacturing parameters from solid body machining to sheet metal forming. By altering the material form (from solid block to sheet metal strip) and the manufacturing method (from machining to bending and joining), the patent achieves pressure-tight sealing with reduced manufacturing complexity.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If solid body machining is used to achieve precise dimensional accuracy, then sealing performance is improved, but production time and cost increase

Engineering Contradiction:
Improvedimensional accuracyVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The sheet metal strip is bent into a tube and connected by seam or toothed form fit, providing sufficient dimensional accuracy for the piston guide without requiring complex solid body machining. This approach significantly reduces production time while maintaining the necessary precision for functional performance.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The sheet metal construction allows for faster, more economical manufacturing compared to solid body machining. The simplified production process enables quicker fabrication and assembly, improving overall productivity while meeting functional requirements.

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

3Manufacturing precision

If complex post-processing steps like honing and deburring are applied to machined surfaces, then surface quality is improved, but manufacturing complexity and time increase

Engineering Contradiction:
Improvesurface qualityVSAvoidpost-processing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The sheet metal strip inherently provides a smooth surface quality suitable for the piston guide application without requiring additional honing or deburring steps. The bending and joining process maintains surface integrity, eliminating the need for complex post-processing operations and reducing manufacturing time.

Inventive Principle:
Principle #30Flexible shells and thin films

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 method enhances the efficiency of the hammer mechanism by increasing the impact energy delivered while reducing energy losses, allowing for a more efficient propulsion system with a simpler and cost-effective manufacturing process.

Implementation Method 1

a combustion chamber (7) for burning a fuel into combustion gases

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

cold forming the sheet metal strip into a piston guide

Methodology Applied
Scientific EffectCold forming: Cold-forming

Data Source

PatentEP2855090B1Fuel-operated setting device
Publication Date: 2016.01.20 HILTI AG
  • EP2855090B1 patent drawingFigure 1
  • EP2855090B1 patent drawingFigure 2~4
  • EP2855090B1 patent drawingFigure 5~6

AI summary

The setting device (1) according to the invention for setting fixing elements (2) has a combustion chamber (7) for combusting a fuel into combustion gases. A drive piston (2) is guided on an inner surface (16) of a tubular piston guide (12). The drive piston (12) is driven by means of the combustion gases in the combustion chamber (7) and the piston guide (13). The piston guide is made of a sheet metal strip (21) which is curved into a tube, the two opposing longitudinal edges (22) of said sheet metal strip being connected by a seam (24) and/or a toothed form-fit (23).