Laser-Welded Piston Unit for Pressure-Tight Rod Coupling
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Solution Overview
Problem
Existing piston unit coupling methods, such as positive-locking and material-bonding, face challenges like loosening, high material and cost intensity, and thermal stress, making them inefficient and costly, especially in hydraulic systems where dynamic loads are common.
Innovation Solution
A piston unit with a piston and piston rod connected via a circumferential laser ring weld seam, which provides a strong, pressure-tight, and low-thermal-stress bonding, reducing material consumption and machining needs, and allowing for high precision and concentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If positive-locking or force-locking couplings are used to connect piston and piston rod, then mechanical strength is improved, but additional measures are required to prevent loosening and machine-molded sections require full forming or great wall thicknesses
Solution Approach 1:
The patent merges the piston and piston rod into a single integral component through laser welding, eliminating the need for separate coupling mechanisms. This combining approach removes grooves, threads, and additional locking measures while maintaining coupling strength through the welded joint.
Solution Approach 2:
The patent replaces mechanical coupling systems (positive-locking, force-locking) with a material-bonding approach using laser welding. This substitution eliminates the need for machine-molded sections, grooves, and threads, allowing for thinner wall thicknesses while maintaining structural integrity.
2Reliability
If material-bonding coupling by gluing is used to connect piston and piston rod, then loosening prevention is improved, but connection strength and security against failure are reduced
Solution Approach 1:
The patent changes the bonding parameter from chemical adhesion (gluing) to metallurgical bonding (laser welding). This parameter change achieves both loosening prevention and high connection strength by creating an integral material bond that matches the strength of the base materials.
3Strength
If welded joints are used to connect piston and piston rod, then connection strength is improved, but thermal stress causes material structure changes requiring thicker wall thicknesses
Solution Approach 1:
The patent uses laser welding technology which substitutes conventional welding methods. This substitution enables precise control of thermal input, creating narrow, tapered weld seams with minimal thermal stress, thereby avoiding material structure changes and eliminating the need for thicker wall thicknesses.
Solution Approach 2:
The patent creates local quality in the weld seam by producing a narrow, tapered, V-shaped connection with concentrated heat input. This localized welding approach minimizes thermal stress distribution while maintaining strong connection at the joint, avoiding the need for increased wall thickness.
4Manufacturing precision
If conventional machining of piston and piston rod is used, then coupling precision is improved, but material consumption and cost increase
Solution Approach 1:
The patent replaces conventional mechanical machining with laser welding technology. This substitution eliminates the need for material removal through machining, thereby reducing material consumption while achieving precise coupling through the welded joint.
Solution Approach 2:
The patent merges the piston and piston rod into a single integral component, eliminating the need for separate machining operations on both parts. This combining approach reduces total material consumption by eliminating machining allowances and material waste.
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 achieves high operational safety, reduced material usage, and lower thermal stress, enabling reliable performance under dynamic loads with minimal additional sealing requirements and reduced thermal distortion, thus enhancing the mechanical load capacity and manufacturing efficiency.
Implementation Method 1
the piston and piston rod are connected in a material-bonding (integrally connected) manner by means of a circumferential laser ring weld seam
Data Source
AI summary
A piston unit of a working cylinder includes a piston and a piston rod. The piston has an axial bore hole formed therein. The piston rod is received in the axial bore hole. The piston rod and the piston are connected by a material-bond by a circumferential laser ring weld seam. The laser ring weld seam defines a pressure medium-tight sealing plane.