1. Project Background
Sichuan Jing Shang Sewing Machinery Co., Ltd., a subsidiary of Zhongfeng Heavy Industry Group, specializes in the research, development, production, and sales of sewing machinery. As an industry leader, its clientele spans the globe.
In response to the COVID-19 outbreak during the 2020 Spring Festival, Jing Shang transitioned to manufacturing protective clothing equipment—specifically, hot air seam sealing machines. Leveraging their extensive experience in sewing machinery design, the company rapidly developed the mechanical structure. However, lacking an in-house electrical engineering department, they relied on external suppliers for electrical integration.
Previously, external suppliers implemented a control system comprising a Fanyi high-definition screen and a microcontroller, which met basic control logic requirements. However, the system exhibited prolonged heating times to reach the set temperature. As the client delved deeper into the equipment’s process requirements, the need for an upgraded control system became apparent, especially given the existing system’s maintenance and upgrade challenges.
2. Solution Overview
Based on the customer’s input/output points and control requirements, an EA compiled all-in-one machine is adopted to mainly achieve 2-axis stepping control, 1-channel analog temperature heating control, and other logic controls.
3. System Configuration
GC-070B-32MAA-C (1 unit)
- Inputs:7 digital inputs, 1 K-type thermocouple temperature input
- Outputs:9 digital outputs, including: 2 pulse outputs for controlling two stepper motors, 1 analog output (4–20 mA) for temperature heating control
4. Process Flow
4.1 Heating Control:
The system employs a built-in PID algorithm, utilizing a 4–20 mA analog output to regulate heating. PID parameters can be auto-tuned with a single key, ensuring rapid temperature rise and maintaining stability within ±1°C.
4.2 Process Control:
Depending on the on/off status of the left and right foot pedal switches, different actions are executed by cylinders or stepper motors.
4.3 Differential Speed Control for Upper and Lower Steppers:
The HMI allows setting differential speed ratios between the upper and lower motors, enabling the rollers to rotate at varying speeds. This innovative design addresses issues like uneven sealing caused by roller slippage.
4.4 Process Overview:
While the process requirements for such equipment are generally consistent, different manufacturers, based on their understanding of the process or production cost considerations, have adopted various actuators, leading to differences in control systems. For instance:
4.4.1 Heating Control:
Some use PT100 temperature sensors, others use K-type thermocouples.
Output methods vary between switch outputs and analog outputs.
This document adopts a K-type thermocouple for temperature detection combined with a 4–20 mA analog output.
4.4.2 Roller Control:
- A single DC motor drives two rollers through mechanical structures, controlling length via time and speed.
- A single stepper motor drives two rollers through mechanical structures, controlling via time or length settings.
- Two stepper motors independently control two rollers, managing length settings.
This document adopts this approach.
4.4.3 Swing Arm Structure:
- A single cylinder drives the swing arm up and down without position sensors; the hot air nozzle enters the fabric at an angle.
- A single cylinder drives the swing arm up and down with position sensors; the hot air nozzle enters the fabric at an angle.
This document adopts this approach.
- Two cylinders or other mechanical structures drive the swing arm with position sensors, allowing the hot air nozzle to enter the fabric vertically. This approach has been tested and can enhance production quality but may extend the production cycle and demands higher mechanical structure requirements. The client has not yet implemented this method.
5. HMI Interface
Operation Interface
6. On-site Photos
