1What can the injection molding machine produce
Automotive industry: car lamp housings, most car interior parts, car bumpers, etc.
Electronics industry: mobile phone casings and some mechanical components, notebook computer casings, desktop computer monitor casings, mouse, keyboard, USB, etc.
household appliances
: TV casings, washing machines, refrigerators, hair dryers, telephones, power switches, sockets, kettle handles and bases, etc.
Daily necessities: microwave lunch boxes, water cups, plastic stools, plastic tables, plastic sorting boxes, plastic flower pots, plastic dustpans, plastic bowls, plastic basins, plastic toys, drinking water
Water machine casing, clothes rack, etc.
Cosmetics industry: part of cosmetic packaging (bottles, caps), etc.
Medical industry:- Disposable syringes, devices for volume adjustment on infusion tubes, etc.
Office supplies industry: whiteboard pens, ink pens, rulers, document racks, printer casings, copier casings, fax machine casings, etc.
Most of the plastic things around us are injection-molded, except for films and bottles with big belly that are made by blow molding, blister molding or thermoforming.
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2 The working principle of the injection molding machine
The working principle of the injection molding machine is similar to that of the injector for injection.
The process of obtaining the product after curing and shaping.
Injection molding is a cyclic process, each cycle mainly includes: quantitative feeding - melt plasticization - pressure injection - mold filling and cooling - mold opening and removal. After taking out the plastic part, it is closed again
mode, and proceed to the next cycle.
Injection molding machine operation items: Injection molding machine operation items include control keyboard operation, electrical control system operation and hydraulic system operation. The injection process actions are performed separately,
Selection of feeding action, injection pressure, injection speed, ejection type, temperature monitoring of each section of the barrel, adjustment of injection pressure and back pressure, etc.
The molding process of the general screw injection molding machine is as follows: first, the granular or powdery plastic is added into the barrel, and the plastic is melted by the rotation of the screw and the heating of the outer wall of the barrel.
state, and then the machine closes the mold and moves the injection seat forward, so that the nozzle is close to the gate of the mold, and then pressurized oil is injected into the injection cylinder to push the screw forward, so that the high pressure
The molten material is injected into a closed mold with a relatively low temperature by force and a relatively fast speed.
Products (the purpose of pressure keeping is to prevent the reversal of molten material in the cavity, replenish materials into the cavity, and ensure that the product has a certain density and dimensional tolerance). The basics of injection molding
Seeking is plasticizing, injection and molding. Plasticization is the premise of realizing and ensuring the quality of molded products, and in order to meet the requirements of molding, injection must ensure sufficient pressure and speed. same
When the injection pressure is high, a correspondingly high pressure is generated in the mold cavity (the average pressure in the mold cavity is generally between 20 and 45MPa), so there must be a large enough mold clamping
force. It can be seen that the injection device and the clamping device are the key components of the injection molding machine.
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❸) Types and characteristics of injection molding machines
Vertical injection molding machine
1. The injection device and the clamping device are on the same vertical centerline, and the mold is opened and closed in the up and down direction. Its spot area is only about half of that of the horizontal machine.
The productivity of the land area is about twice as high.
2. It is easy to realize insert molding. Because the mold surface faces up, inserts are easy to place and position. It adopts the model with fixed lower platen and movable upper platen, belt conveyor and manipulator.
Combined, fully automatic insert molding can be easily achieved.
3. The weight of the mold is supported by the horizontal template to open up and down, and the phenomenon that the template cannot be opened and closed will not occur, which is similar to the horizontal machine due to the gravity of the mold.
It is beneficial to maintain the accuracy of machinery and molds for durability.
4. Each plastic part cavity can be taken out by a simple manipulator, which is conducive to precision molding.
5. The surrounding of the clamping device is generally open, and it is easy to configure various automation devices, which is suitable for automatic molding of complex and delicate products.
6. The belt conveying device is easy to install through the middle of the mold, which is convenient for automatic molding production.
7. It is easy to ensure the consistency of the resin fluidity in the mold and the mold temperature distribution.
8. Equipped with rotating table, moving table and inclined table, etc., it is easy to realize insert molding and in-mold combined molding.
9. In small batch trial production, the mold structure is simple and low cost, and it is easy to unload.
10. Having withstood the test of many earthquakes, the vertical machine has better seismic resistance than the horizontal machine due to its low center of gravity.
Horizontal injection molding machine
1. Even if the mainframe is low, there is no height limit for the plant where it is placed.
2. When the product can be dropped automatically, automatic molding can be realized without using a manipulator.
3. Due to the low body, the feeding is convenient and the maintenance is easy.
4. The mold needs to be installed by crane.
5. When multiple units are arranged side by side, the molded products are easily collected and packaged by the conveyor belt.
Angle injection molding machine
The axis of the injection screw of the angle injection molding machine and the movement axis of the mold clamping mechanism template are arranged perpendicular to each other, and its advantages and disadvantages are between the vertical and horizontal. Because of its injection direction and mold division
The profiles are on the same plane, so the angle injection molding machine is suitable for molds with asymmetric geometry with side gates or products that do not allow gate marks in the molding center.
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4) How to choose the injection molding machine
1. Select the right type: The model and series are determined by the product and plastic.
Since there are many types of injection molding machines, it is necessary to correctly determine which type of injection molding machine this product is suitable for, such as vertical and horizontal injection molding machines, or which series of injection molding machines. such as general thermoplastics
Or bakelite raw materials or PET raw materials, etc., which are single-color, double-color, multi-color, interlayer or mixed color, etc. In addition, some products require high stability (closed loop), high precision, ultra-high firing rate, high
Conditions such as injection pressure or rapid production (multi-loop) must also select the appropriate series for production.
2. Can be put down: Determine whether the inner distance of the large column of the machine, "mold hall, "minimum size of mold" and "mold plate size" are appropriate according to the size of the mold, so as to confirm whether the mold can be put down.
(1) The width and height of the mold must be less than or at least - the side is less than the inner distance of the large column.
(2) The width and height of the mold are preferably within the size range of the mold plate.
(3) The thickness of the mold should be between the mold thickness of the injection molding machine.
(4) The width and height of the mold must meet the minimum mold size recommended by the injection molding machine, and it will not work if it is too small.
3. Take it out: It is determined by the mold and the finished product whether the "opening stroke and" the mold supporting stroke are enough to allow the finished product to be taken out.
(1) The mold opening stroke must be at least twice the height of the finished product in the direction of opening and closing the mold, and the length of the sprue must be included.
(2) The stroke of the mold should be enough to eject the finished product.
4. Can be locked: The tonnage of "clamping force" is determined by the product and plastic.
When the raw material is injected into the mold cavity at high pressure, a mold-pulling force will be generated, so the clamping unit of the injection molding machine must provide enough "clamping force" to prevent the mold from being stretched. Mode locking
The force requirement is calculated as follows:
(1) Calculate the projected area of ​​the finished product in the direction of the opening and closing die from the appearance size of the finished product.
(2) Supporting mold force = projected area of ​​finished product in the direction of mold opening and closing (cm2) x number of mold cavities x mold pressure (kg/cm2). .
(3) The pressure in the mold varies with the raw material: - The general raw material is 350~ 400kg/cm2.
(4) The clamping force of the machine should be greater than the clamping force of the die, and for the sake of insurance, the clamping force of the machine should usually be more than 1.17 times that of the clamping force.
So far, the specifications of the clamping unit have been preliminarily determined, and the tonnage of the model has been roughly determined. Then the following steps must be performed to confirm which injection unit has the correct screw diameter.
fit the need.
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5) Operating procedures of injection molding machine
1.1 Preparations before starting the injection molding machine
1. Clean up the environment of the equipment, and it is not allowed to store items unrelated to production.
2. Clean the workbench and the internal and external sundries of the equipment, and wipe the injection guide seat and the tie rod of the clamping part with clean cotton sand.
3. Check whether the control switches, buttons, electrical circuits, operating handles and handwheels of the equipment are damaged or malfunctioning. Each switch and handle should be in the "off" position.
4. Check whether the safety protection devices of all parts of the equipment are in good condition and work sensitively and reliably. Check whether the test "emergency stop" is effective and reliable, and whether the safety door slides flexibly.
Whether the limit switch can be triggered.
5. The safety protection devices on the equipment (such as mechanical lock levers, stop plates, various safety protection switches, etc.) are not allowed to be moved casually, and are not allowed to be modified or deliberately disabled.
6. Check whether the screws of each part are tightened and loose. If any abnormal or damaged parts are found, report to the foreman, and the foreman will deal with it by himself or notify the maintenance personnel to deal with it.
7. Check each cooling water pipeline, try running the water, check whether the water flow is smooth, whether it is blocked or leaking.
8. Check whether there are foreign objects in the hopper. No items are allowed to be stored above the hopper. The hopper cover should be covered to prevent dust and sundries from falling into the hopper.
1.2 Start the injection molding machine
1. Turn on the main power switch of the machine tool, check whether the equipment is leaking, and preheat the barrel and mold according to the set process temperature requirements. When the barrel temperature reaches the process temperature, it must be
Keep it warm for more than 20 minutes to ensure that the temperature of each part of the barrel is uniform.
2. Open the cooling water valve of the oil cooler, cool the oil return and water pipes, and start the oil pump by jogging. If no abnormal phenomenon is found, the oil pump can be officially started, and the display will show on the screen.
"The horse can only operate after it is opened, and check whether the safety gate is functioning properly.
3. Manually start the screw rotation and check whether the screw rotation sound is abnormal or stuck.
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6) Maintenance of injection molding machine
1. Daily inspection
Check and adjust all safety facilities every day. You must ensure that all safety facilities are normal before you can use the machine; check the amount of oil in the lubricating oil tank, you must add the same brand
Check the oil level on the hydraulic oil tank, if the oil level drops below the center line of the liquid level gauge, add hydraulic oil to the center line, and must add new oil of the same grade: the first injection
After 1000 hours of operation, it is necessary to replace or clean the oil suction filter, hydraulic oil, and clean the oil tank; when it runs for 5000 hours or at most one year, it is necessary to replace or clean the air filter and fluid
Pressure oil, pay attention to the old and new hydraulic oil can not be used warm; when running for 20,000 hours or at most 5 years, check and replace the sealing ring and wear ring of the hydraulic cylinder, and replace the high-pressure hose; every 3
year, replace the battery of the controller (host): every 5 years, replace the battery on the operation panel.
2. Pay attention to lubrication
During the use of the injection molding machine, it is necessary to regularly observe whether the lubrication points of the injection molding machine are in normal working condition. Note that the time for each lubrication must be sufficient to ensure the entire lubrication
Every lubrication point of the system is well lubricated. The lubrication module (interval time) of the machine and the time of each lubrication are realized by the reasonable setting of computer parameters. regular observation
The working condition of the sliding system, keep the lubricating oil in the oil tank at a reasonable oil level. If poor lubrication is found, it should be lubricated in time, and the lubrication condition of each lubrication point should be checked to ensure that the machine
Good lubrication.
3. Check the air cleaner
The function of the fuel tank air filter is to breathe the fuel tank and prevent the external dust and other dirt from entering the fuel tank. Therefore, it is a very important part and needs regular maintenance.
The air filter is installed on the top of the fuel tank. When cleaning, first loosen the cover, replace the air filter element, and then re-tighten the cover. Note that the cover must be tightened, otherwise the oil will splash
out.
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