Customers want to receive quality welded products on time. Suppliers can achieve this in two ways - reactively or proactively. Reactive means not doing any preventive planning or analyzing the true welding process capabilities of each ship component welding system, whether manual, machine or robotic.
Proactive Intelligent Process Control
A proactive approach means designing for manufacturing, employing capable processes, and working with intelligent systems, which can also be human, machine, or robotic based. The levels of intelligent processing and proactivity are shown below.
Intelligent Automation Level Active/Passive Level
Manual welding Can be done simultaneously
Blind (no vision) machine or robot Reactive
Automatic pre-check of joint fit Active
Real-time gap tracking Active/active
Real-time seam tracking with adaptive control Active-adaptive correction
Laser vision system inspection Reactive but more accurate
Weld inspection measurement system active
Closed-loop control of the process Proactive
Repair based on automatic weld inspection Active and passive
Feed-forward ID of parts that are not welded to specification Active and passive
Let's look at some specific applications of these systems, starting with the manual portable weld inspection system (PWIMS).
Portable Weld Inspection Management System (PWIMS)
Currently, there is a large amount of redundant and subjective inspections performed on all types of ship structures. It is not uncommon to perform 400% inspections on some welds, resulting in wasted time and unnecessary repairs.
Improvements to this situation are now possible and can be deployed in many applications.
The system consists of a portable, handheld laser vision sensor and a database management tool. It provides objective weld feature measurement and SPC analysis tools.
Real-time seam tracking and adaptive processing
A typical rebar welding machine consists of a gantry, welding equipment, and heavy-duty clamping devices. Historically, the wire was manually jogged or a probe seam tracker was used to keep the wire in the correct position at the joint. Smarter welding can be accomplished with a laser vision seam tracker that can:
identify if the weld is within tolerance;
track the weld in real time; and
adjust the welding process to optimize weld quality. To achieve precise welds (minimal over-welding) at top speeds, traditional methods will not work.
Closed-loop control
Laser hybrid processes consisting of high-power lasers and gas metal arc welding equipment are beginning to make inroads into shipbuilding components. One of the biggest advantages is more precise welding, resulting in less distortion. To achieve optimal control and quality, one manufacturer has deployed a closed-loop control system that measures the weld shape after it solidifies and then feeds this information back to the other party for continuous correction. Travel speed and laser or GMAW parameters can be automatically adjusted as needed.
Summary
How to get the best welding performance, design for fabrication means considering the welding process to be used and its capabilities during the planning stage. Also, consider the design for automated processes and inspections. This will give you a good chance of getting the job done right the first time.
