Suzhou Midtech Machinery Co., Ltd. hopes to make progress together through experience sharing and exchanges with global friends and business partners. What we are sharing with you this time is the installation and debugging of the conical twin-screw extruder production line, summarizing some of our experiences and insights during the equipment installation process.
- Introduction to Conical Twin Screw
1、Introduction to Conical Twin Screw
(1) Introduction to twin-screw extruder
There are many types of twin-screw extruders, which can be divided into two categories: meshing and non meshing. The meshing twin-screw extruder can be further divided into two categories: co rotating and counter rotating.
The twin-screw extruder includes multiple systems, and the screw system mainly completes the plasticization and conveying process of materials, which has a significant impact on the performance and quality of the finished products.
① Feeding system: including hopper, mixing motor, and feeding motor. It can prevent material accumulation and facilitate its smooth entry into the feeding port.
② External heating system: mainly uses heating rods and cylinders to efficiently heat materials and promote plasticization.
③ Cooling system: A heat exchange system composed of thermal oil or water is used to reduce the heat of the body, thereby effectively controlling the temperature of the cylinder.
④ Hydraulic screen changing system: Use replaceable filter screens to intercept impurities, improve plasticization degree, and ensure the uniformity and stability of the quality of the produced materials.
⑤ Vacuum system: Extract moisture and other low molecular weight volatiles from the material.
⑥ Electronic control system: responsible for monitoring and controlling the relevant equipment of the main and auxiliary material systems.
⑦ Screw system: The most important component of an extruder, which can be divided into conveying section, melting section (exhaust port), plasticizing section (vacuum port), and discharge section.
2.Installation instructions:
① The ground where the equipment will be installed should be leveled and kept clean.
② Determine the location for installing the equipment and make proper markings to ensure that each machine can be accurately placed in the designated installation position.
③ Transport the equipment to the designated installation location in sequence according to the equipment layout diagram. (When transporting equipment, choose a transport machine that can afford the weight of the equipment to prevent unnecessary personal injury).
④ After all devices are transported to the installation location, each device should be accurately arranged according to the dimensions on the site layout plan. The calibration level should also ensure the center height.
⑤ After all the equipment is arranged, check that the components that need lubrication for each machine (gearbox, reducer, screw, slide rail) have lubricating oil and grease. If these areas are not filled with lubricating oil and grease, it will cause rapid damage to the equipment. At the same time, check all devices again for any damage to the components.
⑥ Connect the electric circuit, water circuit, and air circuit according to the labels on the machine before debugging. (The connection of the circuit requires professional electrician operation)
3.Debugging instructions:
① Before starting the production line, check whether the main distribution box and external power aviation plug base are normal. Notify maintenance personnel promptly upon discovering any abnormalities for repair. Make sure there are no issues before turning on the power.
② Check for any damage to the main power supply, front and rear auxiliary power lines, and heating lines. (including connecting unconnected lines inside the electrical box according to the corresponding numbers on the lines and checking for loose wires caused by bumps during transportation)
③ After turning on the main power switch of the production line, the operator uses an electric pen to check for any leakage in the production line. Confirm that there is no leakage phenomenon before proceeding to the next step.
④ Before starting up, tighten all fastening bolts and nuts again to ensure that all nuts and bolts are tightened before starting up.
⑤ When starting up, first jog the start switch of each motor (low-speed operation) to observe whether the rotation direction of the motor is correct. If there is a motor with incorrect rotation, adjust the circuit to ensure that the motor rotates correctly.
⑥ When starting up, first rotate the machine at a low speed of 5-10 revolutions per minute, then slowly increase the speed of the main machine and the feeding speed according to the current of the main machine. When the machine is running normally, it is advisable not to exceed 80% of the rated current of the main machine. If the rated current is exceeded, stop feeding immediately. If the machine exceeds the rated current and stops on its own, do not attempt to start it. Wait until the screw is cleaned before starting it again, otherwise it will cause damage to the machine and mold parts.
⑦ After the material comes out of the mold mouth, observe whether the material has reached a fully plasticized state. If not, wait for the material to fully plasticize before entering the shaping mold. Otherwise, it is not easy to produce perfect products. At the same time, it is also necessary to observe whether the discharge volume around the mold mouth is consistent. If it is not consistent, the method of adjusting the mold temperature or correcting the mold can be adopted.
⑧ During the normal production process, it is necessary to observe the pressure of the pressure sensor and the current of the motor at all times (the current should be observed not only on the operation panel but also on the frequency converter to prevent errors between the two). If there is too much fluctuation, immediately reduce the feeding amount or turn off the feeding and prepare to stop the machine for inspection.
⑨ During the heating process, check the temperature of the heater at any time to see if it matches the temperature displayed on the temperature control meter, and check if the temperature measured by the thermocouple is accurate (at the same time, a mercury thermometer can be used to detect it to prevent the heating coil from being burned out when the actual temperature and the displayed temperature are inconsistent)NOTE:When heating, first increase the temperature to 120 ℃-150 ℃ and keep it warm for about an hour, then heat it up to the process temperature of the material. After checking that the temperature in each zone has reached the process temperature, turn on the machine. Do not heat it up to the process temperature at once and turn on the machine.
⑩ When the machine is started, it is forbidden for personnel to stand at the position of the discharge port to prevent the hot air or material inside the organic cylinder from expanding and spraying out, which may cause personal injury.
4.Shutdown instructions:
① When the equipment does not need to be shut down for production, first turn off the feeder, run the machine at low speed, and ensure that all materials inside the machine are squeezed out completely. Then turn off the main power supply, water and gas circuits, and close the valves. (If the material for producing PVC can be put into the machine barrel during shutdown for easy disassembly of the mold)
② 2. Remove the mold and clean the materials inside the mold while there is still residual heat in the machine, ensuring that it can be turned on normally the next time it is turned on.
③ 3. After all the machines have cooled down, the areas that need to be oiled should be rust proofed to prevent rusting caused by prolonged shutdown.
Thank you for reading. If you encounter any problems during the installation process, Midtech welcomes you to write to us and discuss solutions together.
