Pipeline Butt Welding Vise Control for Vertical Force Stability
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Solution Overview
Problem
Current welding machines struggle to manage the force exerted on tubular elements during butt welding when the movable vises assembly is placed higher than the fixed vises assembly, leading to force peaks and hysteresis issues, especially when welding tubular elements arranged vertically or strongly inclined, which results in non-compliant welds.
Innovation Solution
A welding machine with a fluid-dynamic circuit and electronic control unit that simultaneously controls the pressure in both chambers of the fluid-dynamic cylinders, using a servo valve to manage the pressure difference between the chambers, ensuring precise force control and preventing hysteresis by adjusting the pressure imbalance based on the relative positions of the vise assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the movable vises assembly is placed higher than the fixed vises assembly to weld vertically arranged tubular elements, then the welding machine can handle vertical or inclined welding positions, but the weight of the tubular element generates continuous downward force that causes force peaks during the welding phase
Solution Approach 1:
The hydraulic circuit is segmented into two independent pressure control systems, each managing one chamber of the double-acting cylinders. This allows separate control of the outward and inward movement phases, enabling precise force management during the approach and welding phases when the movable vises assembly is positioned above the fixed assembly.
Solution Approach 2:
The system changes the pressure parameter independently in each chamber of the hydraulic cylinders. By adjusting the pressure in the first and second chambers separately, the system can control the force exerted by the movable vises assembly on the tubular element, preventing force peaks even when positioned above the fixed assembly due to gravity.
2Device complexity
If conventional hydraulic circuits control pressure in one chamber at a time, then the system structure remains simple, but the mobile tubular element cannot be gradually accompanied in contact with the fixed element, generating force peaks
Solution Approach 1:
The hydraulic control system is divided into two independent pressure control circuits, each dedicated to controlling the pressure in one chamber of the double-acting cylinders. This segmentation enables precise control of the movable vises assembly's movement, allowing gradual contact and force application during welding without generating peaks.
3Adaptability or versatility
If the movable vises assembly is positioned above the fixed vises assembly, then vertical welding is enabled, but hysteresis problems occur between the pressure supplied to cylinders and the force actually transmitted to the moving vise assembly
Solution Approach 1:
The system incorporates feedback control through independent pressure sensors and control units for each chamber. The control units continuously monitor the pressure in each chamber and adjust it to maintain the desired force transmission, compensating for hysteresis effects that occur when the movable vises assembly is positioned above the fixed assembly due to gravitational influence on the hydraulic fluid.
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
Enables precise and controlled force management during welding, ensuring compliance with standards and preventing hysteresis, allowing tubular elements to be welded vertically or inclined without force peaks, thus ensuring reliable and safe welding.
Implementation Method 1
a fluid-dynamic circuit (100) comprising a pump (101), a tank (102) and lines connecting the pump (101) and the tank (102) to each fluid-dynamic cylinder (30), said fluid-dynamic circuit (100) being configured to feed fluid under pressure simultaneously to the first and second chambers (33, 34) of each fluid-dynamic cylinder (30)
Implementation Method 2
optimally manage the characteristics of the motion (in particular direction, speed and force) imparted to the movable vise assembly, namely to the first vise assembly (10), as a function of the pressure difference ΔP=P1-P2
Implementation Method 3
the weight of the tubular element continually tends to bring the moving vises assembly closer to the fixed vises assembly, generating conditions for which current welding machines are not designed
Data Source
AI summary
A pipeline butt welding machine has support means, a first vise assembly and a second vise assembly associated with the support means and adapted to engage respectively a first and a second tubular element to be joined by welding; at least one of the vise assemblies being movable relative to the other between a position of maximum mutual distance and a position of minimum mutual distance; the mobile vise unit being operatively connected to at least one fluid-dynamic cylinder comprising a casing and a piston slidingly housed within the casing and defining in the casing a first and a second mutually variable volume chamber. The welding machine has a fluid-dynamic circuit configured to feed fluid under pressure simultaneously to the first and second chambers and to control the motion of the movable vise assembly as a function of a pressure difference between the first and second chambers.