Cold Pilger Rolling Mill Force Control via Dynamic Step Length
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Solution Overview
Problem
The challenge in cold pilger rolling mills is to maintain controlled force exertion on the tube shell during the forming process, which affects the quality of the finished tube and the service life of the feed clamping carriage, as the step length and velocity of the tube shell advancement significantly influence the force applied by the tool.
Innovation Solution
A cold pilger rolling mill equipped with a control system and sensor to regulate the step length of the feed clamping carriage based on the detected force, using a direct electromechanical linear drive and a hydraulic or pneumatic brake to ensure precise control and prevent damage, while optimizing productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the step length of the tube shell advancement is increased to improve productivity, then the production speed increases, but the force exerted by the tool on the tube shell becomes uncontrolled and may exceed damage thresholds
Solution Approach 1:
The patent implements a closed-loop feedback control system where sensors continuously measure the force exerted by the rolls and mandrel on the tube shell during cold pilgering. This force measurement is fed back to the control unit, which dynamically adjusts the step length of the feed clamping carriage to maintain force within safe operating limits, thereby preventing damage while optimizing productivity
Solution Approach 2:
The system transitions from fixed, predetermined step lengths to dynamic, adaptive step length adjustment. The control unit modifies the advancement parameters in real-time based on actual force conditions, allowing the process to adapt to variations in tube shell properties, material characteristics, and rolling conditions, thus achieving both high productivity and reliable force control
2Reliability
If the step length is decreased to control the force exerted on the tube shell, then the force remains within safe limits, but the productivity and production speed decrease
Solution Approach 1:
The system dynamically changes the step length parameter based on real-time force measurements and tube shell characteristics. By continuously adjusting this critical parameter, the system maintains force within safe limits while maximizing productivity, avoiding the need for conservative fixed step lengths that would reduce overall production speed
3Device complexity
If a fixed step length is used for the feed clamping carriage, then the device complexity is reduced, but the service life of the feed clamping carriage decreases due to uncontrolled force peaks
Solution Approach 1:
The feedback control system monitors force in real-time and adjusts the feed clamping carriage operation accordingly, preventing force peaks that would cause premature wear and damage. This extends the service life of the feed clamping carriage and other components while maintaining reasonable system complexity through the use of standard sensors and control units
4Productivity
If the step length is increased to maintain optimal productivity, then the production efficiency is maximized, but the quality of the finished tube may deteriorate due to uncontrolled deformation
Solution Approach 1:
The force measurement and feedback control system ensures that deformation occurs within optimal ranges by preventing both excessive force (which causes defects) and insufficient force (which reduces productivity). This maintains tube quality while maximizing production efficiency through dynamic step length adjustment
Solution Approach 2:
The system dynamically adapts the step length to match the actual deformation characteristics of the tube shell, allowing optimal productivity to be maintained across different tube specifications, material grades, and wall thicknesses, thereby ensuring consistent quality throughout production
Data Source
AI summary
A cold pilger rolling mill for forming a tube shell to a tube includes a feed clamping carriage for receiving the tube shell and with a drive that is arranged to move the feed clamping carriage such that during the operation of the cold pilger rolling mill the tube shell moves step-by-step in the direction of the tool. A control and a sensor detect a measure of a force exerted during the operation of the cold pilger rolling mill by the tool onto the tube shell, and wherein the control is connected to the drive and the sensor. The control is arranged to regulate, during the operation of the cold pilger rolling mill, the step length per advance step with which the drive moves the feed clamping carriage to the tool as a function of the measure for the force, which measure is detected by the sensor.