Safety knowledge of injection molding machine

injection molding machine
Injection molding machine is also known as injection molding machine or injection molding machine. It is the main molding equipment for making various shapes of plastic products from thermoplastic or thermosetting plastics using plastic molding molds. It is divided into vertical type, horizontal type and all-electric type. The injection molding machine heats the plastic and applies high pressure to the molten plastic to make it shoot out and fill the mold cavity.
brief introduction
Injection molding machine is usually composed of injection system, mold closing system, hydraulic transmission system, electrical control system, lubrication system, heating and cooling system, safety monitoring system, etc.
Injection system
Function of injection system: The injection system is one of the most important components of injection molding machine, and generally has three main forms: plunger type, screw type and screw pre-plastic plunger injection type. At present, the screw type is the most widely used. Its function is that in a cycle of the injection molding machine, a certain amount of plastic can be heated and plasticized within a specified time, and the molten plastic can be injected into the mold cavity through the screw under a certain pressure and speed. After the injection, the molten material injected into the mold cavity shall be kept in shape.
Composition of injection system: The injection system is composed of plasticizing device and power transmission device.
The plasticizing device of the screw injection molding machine is mainly composed of the feeding device, the barrel, the screw, the gluing component and the nozzle. The power transmission device includes the injection cylinder, the injection base moving cylinder and the screw driving device (glue melting motor).
Safety knowledge of injection molding machine. Figure 1
Mold closing system
Role of mold closing system: the role of mold closing system is to ensure that the mold is closed, opened and ejected. At the same time, after the mold is closed, enough mold locking force is supplied to the mold to resist the mold cavity pressure caused by molten plastic entering the mold cavity and prevent the mold from opening, resulting in the bad status of the product.
Composition of the mold closing system: the mold closing system is mainly composed of the mold closing device, the machine winch, the mold adjusting mechanism, the ejection mechanism, the front and rear fixed template, the moving template, the mold closing cylinder and the safety protection mechanism.
Hydraulic system
The function of the hydraulic transmission system is to provide power for the injection molding machine according to various actions required by the process, and to meet the requirements of pressure, speed, temperature, etc. required by various parts of the injection molding machine. It is mainly composed of various hydraulic components and hydraulic auxiliary components, and the oil pump and motor are the power sources of the injection molding machine. Various valves control the oil pressure and flow to meet the requirements of injection molding process.
electric control
The electrical control system and the hydraulic system can cooperate reasonably to realize the process requirements (pressure, temperature, speed, time) and various program actions of the injection machine. It is mainly composed of electrical appliances, electronic components, instruments (see the right figure below), heaters, sensors, etc. There are generally four control modes, manual, semi-automatic, full-automatic and adjustment.
Heating/cooling
The heating system is used to heat the barrel and the injection nozzle. The barrel of the injection molding machine generally uses the electric heating coil as the heating device, which is installed outside the barrel, and is detected by sections with thermocouples. Heat conduction through the cylinder wall provides heat source for material plasticization; The cooling system is mainly used to cool the oil temperature. Too high oil temperature will cause various faults, so the oil temperature must be controlled. The other place to be cooled is near the blanking opening of the material pipe to prevent the raw material from melting at the blanking opening, resulting in the abnormal blanking of raw material.
lubrication system
The lubrication system is a circuit that provides lubrication conditions for the relative moving parts of the injection molding machine, such as the moving template, the mold adjusting device, the connecting rod hinge, and the injection table, in order to reduce energy consumption and improve the service life of the parts. The lubrication can be either regular manual lubrication or automatic electric lubrication;
safety monitoring
The safety device of injection molding machine is mainly used to protect human and machine safety. It is mainly composed of safety door, safety baffle, hydraulic valve, limit switch, photoelectric detection element, etc., to realize the interlocking protection of electrical-mechanical-hydraulic.
The monitoring system mainly monitors the oil temperature, material temperature, system overload, and process and equipment faults of the injection molding machine, and indicates or gives an alarm in case of any abnormality.
Section I Safety requirements for the mold closing part of the injection molding machine
1. When the safety door is closed, it must be ensured that it cannot be opened automatically. When the safety door is opened in advance, the mold closing action should be terminated.
2. The safety door can prevent any person or object from entering the dangerous area, protect the personnel from being injured by splashing molten plastic, and cannot be damaged or removed for use.
3. When any part of the body wants to enter the working area of the machine to handle abnormalities, be sure to turn off the motor, and turn off the main power supply if necessary.
4. When adding lubricating oil to the big column and crank arm, it is necessary to stop the machine. It is strictly forbidden to do this when the machine is in normal operation.
5. The safety bar and safety stop are flexible and effective. The effective distance between the safety bar and the safety stop is 5~10CM.
6. It is forbidden to bind the electrical limit switches of the front and rear safety doors with ropes.
7. When dismantling large parts such as forest columns and bent arms for repair, triangular belts shall be used for hoisting, and ropes such as steel wire ropes shall not be used for hoisting to prevent injury to the machine and maintenance personnel.
8. The sliding plate of the moving formwork shall be balanced and cannot be adjusted randomly. If it needs to be adjusted, it shall be carried out by the machine manufacturer.
9. It is forbidden to bind the electrical limit switches of the front and rear safety doors with ropes.
Section II Safety requirements for injection and hydraulic device
1. The back plate of the fixed mold base shall be equipped with a glue injection protection device to ensure that the spray nozzle will not hurt the surrounding people.
2. The safety door glass window shall not be damaged to prevent the molten material from splashing out from the mold cavity and scalding.
3. The hydraulic system shall be equipped with filtering device.
4. The inner wall of the oil tank must be protected and protected against external pollution. When the temperature of the working medium reaches 80 ℃, the protective layer shall be effective.
5. The oil temperature shall not exceed the allowable value, and the maximum temperature shall not exceed 75 ℃. Otherwise, the cooler shall be checked, and there may be blocked conditions and eliminated.
6. Check the quality and quantity of hydraulic oil every half a year to see whether the oil quality is deteriorated and whether the oil quantity is sufficient.
7. All pressure gauges and ammeters must be intact.
8. All oil pipe joints shall be free of oil leakage, and the oil cylinder screws shall not be loose.
9. The hydraulic safety system is mainly realized by the system safety valve in addition to the hydraulic protection safety valve of the protective door. The manufacturer has set the maximum allowable value and closed it. If the pressure value exceeds the set specified value, the system safety valve will be opened. It is strictly prohibited to adjust it without permission.
10. The safety valve limits the pressure of the hydraulic system and protects the operator from the damage caused by excessive pressure at the joint of the rubber hose and the steel pipe; At the same time, it protects against damage caused by hydraulic system error. The safety valve protects the oil pump in the hydraulic drive device from overload, and it is not allowed to adjust the system safety valve under any circumstances.
Section III Safety requirements for circuit and heating device
1. Electrical safety device includes basic grounding wire and emergency brake button; All electrical parts of the machine have
The grounding wire, especially the electric heating part, and the heating ring must be checked regularly.
2. The emergency stop button is respectively set on the operating panel and the protective plate of the fixed template on the non-operating surface. Press
Press the emergency stop button, and all the actions of the machine will stop immediately, including the motor, and all the operating equipment connected with the standard interface will also be turned off. If you want to restart the machine, turn the emergency stop button counterclockwise, and the button will automatically pop up.
3. There should be a protective cover above the electric heating coil of the material barrel to ensure that the electric heating coil will not be directly exposed to the outside.
4. The heating system wiring must be insulated and meet the requirements; When replacing wires, strictly follow the specifications. Do not pull and connect wires randomly or use wires that do not meet the requirements.
5. If the internal wires of the machine are to be replaced, they must be protected with hose heat-shrinkable tubes.
6. In addition to voltage and hydraulic instruments, electrical equipment must be installed separately from machinery to prevent friction and leakage.
7. In the process of use, do a good job of routine spot check, and carefully check whether the wiring ports are not allowed to loose or short circuit, and whether the electronic components are damaged.
Section IV Safety requirements for moulds
1. The cleaning and assembly of the mould shall not be pounded with a steel hammer, but only with a copper rod; Polished surface for forming
The mirror surface shall not be scraped with hard parts, but can only be wiped with clean cotton.
2. At the beginning of production, the mold should be cleaned with cotton rust inhibitor and other dirt, and sprayed with release agent.
3. The ejection pressure and speed cannot be adjusted too much, subject to the smooth ejection of the product.
4. The guide post and guide hole of the mold and the parts with mutual power must be oiled once every shift.
5. When the mold is not produced, it must be sprayed with anti-rust agent; The guide post, guide sleeve and sliding block must be coated with lubricating oil,
It should be placed in the mold library, and it is forbidden to put it in a damp place.
6. During mold test, first use low pressure, low speed and low temperature to form for a long time, and then press the pressure, speed, time
Temperature and sequence adjustment.
Section V Safety requirements for driving
1. The crane operator must have special industry operation certificate and relevant knowledge of crane operation. cooked
Know safe operation procedures and be able to follow them.
2. Before use, check whether the control button can reliably control the lifting and running, and whether there is abnormal noise during operation
Sound, the steel wire rope shall be correctly wound on the drum, and the brake shall be sensitive. In case of any abnormal situation, it can be used only after finding professional personnel to eliminate the fault.
3. It is strictly forbidden to tilt and lift heavy objects and drag heavy objects along the ground with a crane. It is strictly forbidden to lift the mold from the head
After passing or staying, the crane must be lowered to about 50cm above the ground after being lifted out of the machine.
4. Carry out comprehensive maintenance on the traveling crane regularly, add lubricating oil, and maintain the good performance of the traveling crane.
Section VI Workshop environmental requirements
a) The workshop lighting should be appropriate, and the light should meet the requirements of normal work at night.
b) The machine shall be free of oil and water leakage, and the ground shall be clean to prevent slipping when walking.
c) It is not allowed to pull and connect wires randomly to ensure the safety of electricity use.
d) Check the machine and equipment every day to ensure that they are in a safe state.
e) The workshop is properly ventilated, which takes away the waste gas generated during plastic processing and reduces the impact on human body.
Section VII Requirements for safe operation in production
a) Before operation:
① Prepare all necessary auxiliary tools and wear personal labor safety protection equipment;
② The mold is firmly and reliably locked on the molding machine to make it evenly stressed;
③ . Observe whether the mold opening and closing of the empty machine are normal;
④ . Check whether the processing equipment, instruments and meters work normally and whether the guide rail and other parts are well lubricated;
⑤ Start the ventilation device and adjust the length of the safety bar to make it in the correct position.
b) In operation:
① Adjust the molding conditions according to the process documents to prevent the plastic from overheating or hot material
Burn the human body by spraying from the nozzle of the injection molding machine to prevent the generation of toxic gas from dissociating in the operation room and causing harm to the human body;
② . Pay attention to the forming quality of the product and the operation of the equipment at all times. In case of unsafe factors, such as poor ejection, failure of electrical and hydraulic components, the production should be suspended in time. Ask professional personnel to check the causes and eliminate the faults in time;
③ The machine operator is not allowed to leave the work position at will;
④ When the staff is trimming, the blade should be outward, not inward, to prevent the blade from hurting people.
⑤ . In case of product sticking, first return the thimble in place before handling the abnormality to prevent the thimble from hurting people;
⑥ . Check the grounding condition of the machine at any time, and timely ask professional personnel to deal with poor grounding;
⑦ . If the nozzle is blocked, first shoot the molten material in the barrel, then loosen it, wait for 3-5 minutes to release the pressure inside the barrel, and then start to remove the nozzle, otherwise there will be the possibility of the molten material splashing and hurting people.
⑧ When disassembling the nozzle, if the machine is large, it is strictly prohibited to stand under the wrench handle or extension sleeve to prevent the wrench from falling suddenly and hurting people when the nozzle is loose.
c) After operation:
① Clean the site, apply lubricating oil and wipe the equipment to make it clean;
② All operating switches and buttons of the equipment are adjusted to be off;
③ The mold cannot be fully closed to high pressure locking, otherwise, it may not be opened after a long time of shutdown.
Section VIII Safety requirements for auxiliary equipment
a) Common auxiliary equipment includes the following types: drilling machine, polishing machine, mold temperature machine, ice water machine, electric grinder
Electric heating pipe, manipulator, etc.
b) Safety requirements:
Drilling machine: it shall be placed stably, with good insulation, good belt, complete protective cover, and no abnormal sound during operation. It is not allowed to wear gloves during operation. It is not allowed to be half-hearted. In principle, it can only be operated by one person.
Polishing machine: it shall be placed stably, with good insulation, complete protective cover, and no abnormal sound during operation. Gloves shall not be worn during operation, and half-hearted operation is not allowed. In principle, only one person can operate it.
Mold temperature machine: it shall be placed stably, with good insulation. The shell shall not be opened for operation. There shall be no abnormal sound during operation. There shall be no oil or water leakage.
Water chiller: it shall be placed stably, with good insulation. The shell shall not be opened for operation. There shall be no abnormal sound during operation, and there shall be no oil or water leakage.
Electric mill: the insulation is good, the shell cannot be opened for operation, the operation has no abnormal sound, and gloves are not allowed during operation.
Electric heating pipe: the power shall meet the power distribution requirements, the terminal insulation shall be good, the electric heating pipe shall not be too long to avoid touching the machine, especially the dynamic mold. The staff shall be convenient to operate, and shall not be scalded or touch the power line.
Manipulator: generally, when installing the manipulator, there will be safety training, and the relevant operating procedures should be strictly followed. When approaching the manipulator to handle abnormalities, the machine should be stopped. No one is allowed to stand in the manipulator's working travel area.