Electrical Basics of Cold roll forming machine

1. PLC (Programmable Logic Controller) – The Machine’s “Brain”

• What it does: Think of the PLC as the machine’s brain. It runs on pre-written programs, takes signals from sensors and switches, does quick math, and then tells parts like motors or solenoids what to do. It keeps everything moving smoothly—making sure feeding, forming, and cutting happen in the right order, no mess.
• How it works in roll forming:
  • Runs the step-by-step process: It coordinates when the feeder starts, when the rolls spin, and when the cutter kicks in, so the whole line flows without hiccups.
  • Spots problems: If a sensor says “material’s stuck” or “rolls are overworking,” the PLC catches it and might stop the machine or beep to warn you.
  • Remembers settings: It stores different setups for different profiles—like feeding speed or how long to cut. When you switch profiles, just pick the saved one instead of starting from scratch.
• Brands and picking one: Common ones are Siemens (S7-1200/1500), Mitsubishi (FX5U), and Omron (CP1H). Small machines need small PLCs; fancy ones with lots of moving parts need bigger, more powerful ones.

2. HMI (Human-Machine Interface) – Your “Chat Window” with the Machine

• What it does: The HMI is the touchscreen you use. It shows how the machine’s doing—like speed or errors—and lets you tweak settings, control the machine by hand, or check how many parts you’ve made.
• How it works in roll forming:
  • Letting you change settings: You can type in things like “feed 500mm” or “roll speed 20m/min” on the screen, and the HMI passes that info to the PLC.
  • Showing what’s up: It tells you if the feeder’s running, if the cutter’s ready, and displays numbers like “current speed: 15m/min” or “total parts: 800.”
  • Warning you of issues: If something goes wrong—like “no material here” or “servo’s too hot”—the HMI pops up a message (and beeps) and even says how to fix it, like “check if the feeder’s blocked.”
  • Switching modes: You can pick “auto mode” (let it run on its own) or “manual mode” (to test single moves, like nudging the feeder a little).
• Tips for using it: Wipe the screen now and then with a soft cloth and alcohol—grease or dust can make it hard to tap. Also, set up permissions so only managers can mess with important programs.

3. Encoder – The “Measuring Tape” That Tracks Movement

• What it does: An encoder turns movement—like a motor spinning or a roller turning—into electrical signals (little pulses). It’s like a super accurate ruler or speedometer, so the machine knows how far something’s moved or how fast it’s going.
• How it works in roll forming:
  • Controlling how much material feeds: An encoder on the feed roller counts pulses as the roller spins. The PLC uses these pulses to figure out how much material has gone through. When it hits the length you want, the PLC stops the feeder—so parts are cut to the right size (usually within 0.5mm of perfect).
  • Keeping speed steady: It works with servo or inverter motors to check their speed. If the motor should be spinning at 1200rpm but is only at 1100, the encoder tells the driver, which adjusts to fix it.
• Types and installing: Most use rotary encoders—cheaper “incremental” ones work for most jobs; “absolute” ones remember their position even when turned off, good for super precise stuff. Mount it straight on the motor or roller shaft (use a coupling) so it doesn’t wobble, and put wires in a shielded tube to keep electrical interference out.

4. Servo System (Servo Motor + Servo Driver) – The “Precision Mover”

• Servo driver: It takes orders from the PLC (like pulse signals), tells the motor how fast or far to move, and uses the encoder to check if the motor’s doing what it’s told. If there’s a tiny mistake, it fixes it right away.
  • Use in roll forming: Controls the feeder to move material exactly (like feeding 500mm with an error of 0.1mm or less) or adjusts roll gaps (using a servo motor to turn a screw, accurate to 0.01mm).
• Servo motor: Unlike regular motors, it’s fast (starts and stops in milliseconds), accurate (can position to 0.001°), and steady (no shaking at low speeds).
  • Use in roll forming: Drives the feeder for precise feeding (great for thin, fancy profiles like solar 支架 or car door frames); adjusts roll gaps to match how thick the material is; positions the cutter so it doesn’t bend the profile.

5. Regular Motor + Inverter – The “Basic Workhorse”

• Regular motor: It turns electricity into motion, powering the main rolls or conveyors. It’s simple, cheap, and easy to fix—good for jobs that don’t need fancy speed control.
• Inverter: It changes the electricity’s frequency to adjust the motor’s speed (since motor speed depends on frequency). It also protects the motor—like starting it gently to avoid big electrical spikes.
  • Use in roll forming: Adjusts the main roll speed (slow for thick material, fast for thin stuff) to match the feeder; saves energy when the motor isn’t working hard; stops the motor if it’s overloaded (like if the rolls get stuck).

6. Proximity Switch – The “Touchless Detector”

• What it does: A proximity switch spots objects without touching them. When something (usually metal) gets close enough (1-30mm), it sends a signal—great for checking if something’s there, where it is, or if it’s moving.
• How it works in roll forming:
  • Detecting where the material is: A switch at the feeder entrance tells the PLC when the material starts (so it can start feeding) or ends (so it can stop and tell you to add more).
  • Checking positions: Switches on the rolls or cutter track their limits—like “rolls are at the highest point” or “cutter is back to start.” The PLC uses this to stop parts from moving too far and breaking.
  • Spotting jams: A switch on the feed roller checks if it’s spinning. If it stops (because of a jam), the switch sends no signal, and the PLC beeps and stops the machine.
• Picking and installing: Pick inductive ones for metal, capacitive for plastic/wood. Get a tough one (IP67) if the workshop is dusty or oily. Mount it so it’s 3-4mm from the object (not too close, not too far), and keep it away from big electrical parts to avoid interference.

Summary