Real-time detection of lubrication failure or abnormalities in carbide drawing dies challengeWe are looking for solutions that can monitor the condition of carbide dies in the wire drawing line and raise early alarms in case of abnormalities.
Steel wires are made by passing wire rods through conically converging dies. As a result of the pulling force on the wire rods through the converging section, the diameter of the wire is reduced. This reduction in diameter of the wires is a gradual process and it takes place by passing the wires through a sequence of dies with gradually decreasing converging sections. The wire diameter and the corresponding size of the die hole vary from 13 mm to 4 mm in sequential decreasing order. These wire drawing dies are made of sintered tungsten carbide (WC). For the purpose of lubrication, dry lubricants are used which forms a thin layer between the wire and die surface to prevent direct contact between them to reduce friction.
At present, there is no direct measurement of friction between die and wire. Lubrication failure may occur whenever there is direct metal to metal contact (die-wire), which increases friction. It can be caused by many factors such as carbide die cracking, insufficient lubricant flow inside die, moisture in lubricants, poor quality of input wire rod used for drawing, poor die cooling etc. Thus, lubrication failure is a random event, which affects the wire quality as it results in the generation of surface defects on wires during drawing, breakage of carbide dies and subsequent loss of productivity.
Currently, lubrication effectiveness is judged by the operator through visual inspection of the wire surface, when the wires are coiled on drawing drum, as depicted in the video. Delay in the identification of lubrication failures results in poor wire quality/surface defects and loss of productivity caused by die failures leading to shutdowns. This is a common problem faced across the wire industry during steel wire drawing operations. In order to supply zero defect product to customers and avoid wire failures, it is necessary to identify the lubrication failure before the defect is generated in the first place. Thus, the challenge is to develop a real-time mechanism for detecting & indicating abnormalities in lubrication and sturdiness of the dies during the process of steel wire drawing.
- Visual monitoring, such as observing the appearance of wire coming out of die box, is carried out by machine operators to identify issues.
- Approaches like measurement of the wire temperature profile, wire drawing force, vibrations etc. to correlate it with friction conditions inside the die.
- Acoustic emission technique was tried to identify die wear inside. This approach was not successful due to inconclusive results.
- Real time monitoring of lubrication inside the die and detection of lubrication abnormalities during the wire drawing process.
- Generation of alarm at the onset of lubrication failure or sudden changes in the lubrication system.
- Based on the alarm, the user (machine operator) should be able to take corrective actions before the wire quality further deteriorates or there is a fracture in the die or wire.
- Additional features like recording the events of lubrication failures, stoppage of machines on detecting abnormality will also be preferred.
- The average wire drawing speed is 20 m/s.
- The temperature of the wires as a result of wire drawing can go up to 130 oC.
- Direct access to drawing die is not possible, as it is submerged in water-cooled chamber.
- Wire surface emissivity varies with the lubricant coating produced during drawing.
- Limitation of space to install sensors.
- Wire breakages during drawing and dust generation (since the lubricants are fine powders) can adversely limit the functioning of sensors/detection method that might be installed in nearby vicinity for inspection purpose.
Awards:- INR 4,00,000R