Laser-Welded Piston Unit for Pressure-Tight Rod Coupling
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Solution Overview
Problem
Existing piston units face challenges such as loosening, high manufacturing effort, thermal stress, and material weakness due to various coupling methods, particularly in hydraulic systems, which affect operational reliability and efficiency.
Innovation Solution
A piston unit is designed with a piston and piston rod connected by two circumferential laser ring weld seams, forming a pressure-medium-tight sealing plane with a narrow, tapered V-shaped weld seam, minimizing thermal stress and material distortion, and allowing for high strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If positive-locking coupling is used to connect piston and piston rod, then mechanical strength is improved, but device complexity increases and manufacturing costs rise due to shaped sections and grooves
Solution Approach 1:
The patent replaces the mechanical positive-locking coupling system with a laser-welded material bond. Instead of using grooves, threads, or shaped sections to achieve mechanical interlocking, the invention uses laser welding to create a direct material bond between the piston rod and piston, eliminating the complex mechanical coupling structure while maintaining or improving connection strength.
Solution Approach 2:
The invention changes the coupling method from mechanical interlocking to thermal bonding through laser welding. This parameter change in the joining process eliminates the need for complex geometric features and reduces manufacturing steps while achieving reliable connection between piston and piston rod.
2Strength
If welded joints are used to connect piston and piston rod, then strength is improved, but thermal stress causes material structural changes requiring thicker walls
Solution Approach 1:
The patent replaces conventional welding with laser welding technology. This substitution uses a highly concentrated energy source that delivers rapid heating and cooling, minimizing the heat-affected zone and reducing thermal stress on the piston rod material, thereby avoiding the need for thicker walls to compensate for thermal damage.
Solution Approach 2:
The laser welding process applies energy in a highly concentrated, periodic manner along the joint line, creating a narrow weld zone with minimal thermal input. This periodic energy delivery allows for strong bonding while limiting the spread of thermal stress to surrounding materials.
3Strength
If conventional welding is used, then material bond strength is improved, but manufacturing complexity increases due to qualified personnel requirements and process complexity
Solution Approach 1:
The patent replaces conventional welding processes with laser welding, which is more automated and easier to control. The laser welding process can be precisely programmed and executed with consistent quality, reducing dependence on highly qualified personnel and simplifying the manufacturing process while maintaining or improving bond strength.
4Stability of the object's composition
If gluing is used to connect piston and piston rod, then loosening prevention is improved, but strength and resistance to failure decrease
Solution Approach 1:
The invention changes the bonding mechanism from chemical adhesion (gluing) to thermal fusion (laser welding). This parameter change in the joining process creates a material bond with strength comparable to the base materials, eliminating the weakness of adhesive bonds while maintaining the stability and prevention of loosening.
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 provides high precision, concentricity, and operational reliability with reduced thermal stress, enabling efficient material use and eliminating the need for additional seals, while maintaining stability under dynamic loads.
Implementation Method 1
The piston rod and the piston are integrally connected by means of two circumferential laser ring welds
Implementation Method 2
the laser welding advantageously creates a particularly narrow, tapered, and essentially V-shaped weld
Implementation Method 3
there is the disadvantage of thermal stress on the coupling partners, which can lead to material structural changes, particularly in the piston rod
Data Source
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AI summary
The invention relates to a piston unit of a working cylinder having a piston (1) and a piston rod (2), wherein: the piston has an axial bore hole (3) in which the piston rod (2) is received; the piston rod (2) and the piston (3) are integrally connected to one another by means of a circumferential laser ring weld (4); and the laser ring weld (4) forms a pressure-medium-tight sealing plane.