Can Body Butt Welding with Dynamic Pressing Force Control

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Solution Overview

Problem

Conventional can body production apparatuses face challenges in achieving accurate and stable welding quality due to high frictional resistance, misalignment, and excessive pressing force, which can lead to deformation or crushing of the butted parts, especially when dealing with longer lengths of trunks and end plates.

Innovation Solution

The apparatus employs a can body production method with a second correction jig and a pressure unit that adjusts the position and pressing force to ensure accurate contact and controlled pressure, using a servomotor-driven system to monitor and adjust the pressing force within a predetermined range, ensuring flatness and preventing deformation during the welding process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pressing force control is performed based on motor load factor monitoring, then the pressing force can be controlled, but high frictional resistance and surface wobbling prevent accurate control

Engineering Contradiction:
Improvepressing force control accuracyVSAvoidcontrol reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the motor load factor-based control system with a direct pressing force detection system using a load cell. This substitution eliminates the indirect and inaccurate method of inferring pressing force from motor load, providing direct and precise measurement of the actual pressing force applied to the butted part.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control system where the pressing force is continuously monitored by a load cell and the pressing force control unit adjusts the pressing force based on the detected value to maintain it within the predetermined range. This closed-loop feedback ensures accurate and reliable control despite variations in frictional resistance or surface conditions.

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If the correction jigs are positioned to ensure contact, then the butted parts can be aligned, but excessive pressing force deforms or crushes the butted parts

Engineering Contradiction:
Improvealignment accuracyVSAvoidbutted part integrity
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent employs a dynamic pressing force control system that continuously monitors and adjusts the pressing force during the welding process. The pressing force is not fixed but is dynamically controlled to maintain a predetermined range, allowing the system to adapt to variations in butted part dimensions or material properties while preventing excessive force that could cause deformation or crushing.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the pressing force parameter from a fixed value to a controlled range based on actual detection. The pressing force control unit adjusts the pressing force parameter dynamically during the process, optimizing it for each specific butted part configuration while maintaining it below the threshold that would cause damage.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If position control of correction jigs is used, then the pressing force can be applied at a set position, but frictional resistance and activation load reduce control accuracy

Engineering Contradiction:
Improveposition control accuracyVSAvoidpressing force measurement accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent replaces the position control-based indirect pressing force estimation with a direct mechanical measurement system using a load cell. This substitution provides accurate pressing force measurement independent of position control inaccuracies caused by friction or activation loads.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a load cell as an intermediary device between the pressure unit and the butted part. This intermediary directly measures the pressing force without being affected by position control issues, frictional resistance, or activation loads, providing accurate feedback for control purposes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3269486B1Can body production apparatus and can body production method
Publication Date: 2022.04.20 MITSUBISHI ELECTRIC CORP
  • EP3269486B1 patent drawingFigure 1
  • EP3269486B1 patent drawingFigure 2
  • EP3269486B1 patent drawingFigure 3

AI summary

Lower surfaces of stepped portions of correction rings disposed at end plates (2) provided at both sides of a trunk (1) and erection portion rear surfaces of the end plates (2) are brought into contact with each other, and a control portion (10A) provided to a pressure unit (10) monitors a load torque of a motor, and presses butted parts through first pressing with a predetermined pressing force by controlling the position of a second correction jig (20B) and automatically performing fine adjustment of position movement of the second correction jig (20B). Thereafter, the control portion (10A) moves the correction rings to form spaces at an upper side, and presses the butted parts through second pressing with a predetermined pressing force by monitoring the load torque of the motor, and the trunk (1), the end plates (2), a first correction jig (20A), and the second correction jig (20B) integrally rotate.