The Three-Side Sealing Bag Making Machine adopts PLC microcomputer control, double-servo and double-variable frequency speed regulation, photoelectric monitoring and deviation correction, and pneumatic conveying technologies. It integrates mechanical, photoelectric, and electrical systems. It features an automatic unwinding, shearing, and tension control system, five-row bridge-type longitudinal sealing heat-sealing knives, a circulating water cooling bonding device, and a heating temperature controlled by a PC. Various special-shaped bag auxiliary bag-making devices can be added as required.
The entire machine is characterized by high automation, excellent product quality, and strong versatility.
It is ideal for producing various composite materials (plastic-plastic, paper-plastic) and is the perfect bag-making equipment for manufacturing center-sealed bags and three-side sealed bags.
1. Prerequisites for Making Three-Side Sealed Bags:
- Use a loading frame where an iron rod slides up and down controlled by an air cylinder for convenient loading. Secure the web roll with screws.
- After loading, wrap the web with a low-pressure wide bag film.
- Rotate the web roll counterclockwise.
2. Tension Control & Film Traction:
- Use a tailstock rubber roller assembly. Press the two rubber rollers together and drive them to rotate via a small motor to traction the film.
3. Unwinding System:
- Equipped with upper and lower receiving rubber rollers that work alternately for receiving the web.
4. Printing Process (Intermediate Step):
- The printing machine is equipped with two upper and lower iron rollers at the front. The upper roller feeds the film, and the lower roller takes it up.
- A tracking device is installed in front of the iron rollers to control the printing error within 1mm by monitoring the left-right swing deviation of the tracked material.
5. Web Roller (Tension Control):
- The web roller is generally made of bamboo mat or plastic. Its primary function is to press the web and control tension.
- An inductive sensor is placed after the web roller to detect the presence of the film in front. This sensor controls the start and stop of the tailstock rubber roller motor. The motor stops when the film is detected and starts when it is not.
6. Hold-Down Plate:
- Made of stainless steel, its purpose is to flatten the film, prevent bag wrinkling, and ensure bag dimension accuracy. Therefore, the hold-down plate must be perfectly flat.
- A light object can be placed on top of the film to flatten it further.
7. Photoelectric Eye (Length Control & Positioning):
- The photoelectric eye controls the bag length, cutting position, and color mark length by tracking the continuous color changes of the three-side sealed bag during printing.
- Adjustment & Calibration: The photoelectric eye can be moved back and forth by adjusting screws at both ends to correct its stopping position (2-3mm).
- Improving Sensitivity: A white paper can be placed under the film directly in front of the photoelectric eye to increase its sensitivity.
- Pattern Calibration: If the pattern is complex, a white paper can also be placed on the pattern to ensure that the pattern under the photoelectric eye is a straight line with no other colors or patterns interfering.
- Selection Criteria for Photoelectric Eye Positioning:
- A relatively flat and straight surface.
- No interference from other patterns in front of the target pattern, otherwise affecting the photoelectric eye's stopping accuracy.
8. Sealing (The Most Critical Step):
- The sealing knife is triangular-shaped, with a set of rollers at each end to ensure the film runs straight through the knife.
- The roller under the knife is typically a heat-resistant silicone roller.
- Both the knife and the silicone roller are covered with a layer of heat-resistant adhesive tape.
- Two copper tiles at the ends of the sealing knife control its vertical movement, requiring regular lubrication.
9. Knife Cloth Replacement:
- First, sand the sealing knife.
- Apply the knife cloth to the center of the knife and spread it evenly to both sides, ensuring no air bubbles or wrinkles in the cloth, as these can cause incomplete sealing (虚封).
10. Adjustment Bar (Error Correction):
- If errors occur in the first nine steps of bag making, the adjustment bar can be used.
- Adjust the height of the iron bar by turning screws to control the film cutting position.
11. Corrugated Rubber Roller & Anti-Static Device:
- The corrugated rubber roller is equipped with springs to prevent the film from sticking to the roller due to static electricity. A dedicated motor controls its operation.
- Anti-static devices are installed both before the sealing knife and after the cutting knife. These devices consist of an iron bar with a row of iron needles.
12. Cutting Process (Final Step):
- The machine uses an upper and lower cutting knife system. The lower knife is fixed with a 5° upward tilt. The upper knife descends to cut the film.
- The knives are typically made of cast iron and require regular lubrication at both ends.
- Adjust the front-back distance between the upper and lower knives by turning the fixing screws of the upper knife.
13. Folding:
- Folding is an automatic process performed by the machine in three steps.
- Word Orientation Control:
- If the printed text should face outward during packaging, the web roll rotates clockwise during unwinding.
- If the text should face inward, the web roll rotates counterclockwise during unwinding.
14. Packaging:
- The three-side sealed bags are now ready for packaging. They can be packed in plastic bags or cartons according to customer requirements.
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