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What is the principle of an injection molding machine? How to choose an injection molding machine?

What is the principle of an injection molding machine? How to choose an injection molding machine?

Issue Time:2020-12-22
What is the principle of an injection molding machine? How to choose an injection molding machine?
Introduction to Injection Molding Machine
 
Injection molding machine is also known as injection molding machine or injection molding machine. It is the main molding equipment that uses plastic molding molds to make plastic products of various shapes. It is divided into vertical, horizontal and all-electric. Injection molding machine can The plastic is heated, and high pressure is applied to the molten plastic to make it eject and fill the mold cavity.
What is the principle of an injection molding machine?
 
In the work of the injection molding machine, when the screw rotates, the plastic will generate friction and mutual movement on the inner wall of the barrel, the bottom surface of the screw groove, the screw edge advancement surface and the plastic and the plastic. The forward advancement of the plastic is this kind of movement combination. As a result, the heat generated by friction is also absorbed to increase the temperature of the plastic and melt the plastic.
 
What are the advantages of servo energy-saving injection molding?
 
1.Using energy-saving devices such as servo controllers and servo motors with excellent performance.
 
2. Sensitive servo control system, quick start response time only needs 0.04S.
 
3. The servo motor and the hydraulic system form a closed-loop control, which greatly improves the repeatability compared with the traditional model.
 
4. Reduce the impact of mold opening and locking, and extend the service life of mechanical parts and molds.
 
5. Reduce the use of electricity. Under ideal working conditions, this model can save 20%-80% compared to traditional injection molding machines. 6. The system heat generation is much lower than traditional injection molding machines, saving about 30% of cooling water. The dosage extends the service life of oil circuit seals and hydraulic parts.
 
7. The noise during operation of the whole line is low, which is significantly lower than that of traditional injection molding machines.
What is the tonnage of an injection molding machine?
 
Injection molding machines usually have two terms to distinguish the size of injection molding machines:
 
1. In terms of tonnage, the ton mentioned here refers to the maximum clamping force of the injection molding machine. For example, a 120 tons injection molding machine refers to an injection molding machine with a maximum clamping force of 120 tons; injection molding machine parts manufacturers.

2.In grams, this refers to the maximum injection weight of the injection molding machine using PE as the raw material. For example, a 200 g injection molding machine means that the maximum injection weight using PE as the raw material is 200 grams.
 
Early injection molding machines used the injection weight (OZ) as the size of the injection molding machine.Later, they were all expressed in terms of the clamping force, so 650 tons = 650 tons of clamping force.
 
What should be paid attention to when the injection molding machine is running?
 
1. The working cycle of the injection molding machine
 
Cooling and holding pressure, according to the set various pressures and time periods, maintain the pressure of the barrel while cooling the mold cavity to form. Locking the mold: the mold plate is quickly approached to the fixed mold plate (including slow-fast-slow speed), and confirm When there is no foreign matter, the system is turned to high pressure, the template is locked (maintaining the pressure in the cylinder), the shooting table is moved forward, and the shooting table is advanced to the specified position (the nozzle is close to the mold).
 
Injection molding: The screw can be set to inject the molten material at the front end of the barrel into the mold cavity at multiple speeds, pressures and strokes. Cooling and pre-molding: The products in the mold cavity continue to cool, while the hydraulic motor drives the screw to rotate to push the plastic particles forward. The screw retreats under the control of the set back pressure. When the screw retreats to the predetermined position, the screw stops rotating, and the injection cylinder is loosened according to the setting, and the expected end.
 
2. Power consumption of injection molding machine
 
The power consumption of the injection molding machine is mainly manifested in the following parts: the power consumption of the circulating cooling water pump. The power consumption of the hydraulic oil pump motor accounts for more than 80% of the power consumption of the entire injection molding machine. The power consumption of the hydraulic system oil pump and the heater Power consumption, so reducing its power consumption is the key to energy saving injection molding machines.
 
3. Excessive temperature rise of the injection molding machine is harmful
 
Excessive temperature rise of the injection molding machine will cause the viscosity of the oil to decrease, increase the leakage, and the volumetric efficiency of the pump and the efficiency of the entire system will be significantly reduced. Due to the decrease in the viscosity of the oil, the oil film of the sliding valve and other moving parts becomes thinner and cut, and friction The increased resistance leads to increased wear and tear, which will shorten the service life of the machine.
How to maintain the injection molding machine daily?
 
1. Do not allow plastic particles, cable ties, packaging materials, etc. to fall on the ground.
 
2. Unused tools and tooling should be evacuated in time, and needed should be placed in a reasonable position.
 
3. The equipment and ground should be kept clean.
 
4. The equipment department performs daily, weekly and monthly maintenance for the injection molding machine, shredder, and manipulator components.
 
How to choose an injection molding machine?
 
The technical parameters of the injection molding machine. When users choose the injection molding machine, they can be judged by vertical or horizontal comparison. The so-called "longitudinal" means that the main technical parameters of the injection molding machine should meet industry standards and be reviewed according to industry standards. The so-called "lateral" Compare the technical parameters of similar injection molding machines. Therefore, this is a very careful scientific work. It should be based on the material, shape, structure, and application fields and specific occasions of the injection molded product; according to the structure, quality, precision, and The number of cavities, the type of runner and its structure, shape, and size; select the parameters of the injection molding machine at all levels according to the daily, monthly, and annual production capacity of the product.
 
When choosing a supplier, it is best to choose a manufacturer with a service office nearby. Because the structure of the injection molding machine is complex, problems will inevitably occur. Fast after-sales service is critical. Don't blindly ask for low prices when purchasing. The accessories on the injection molding machine are domestically produced. There is a big difference between the price of imported and imported products, so you need to try to figure out what brand of accessories the manufacturer uses. Of course, you can’t see some accessories, such as oil seals, bearings, etc., so at this time the manufacturer’s reputation and credibility are very good The essential.
 
Select the model, the two main parameters of the injection molding machine are the injection volume and the clamping force. In order to ensure the quality of the processed product, the weight of the actual mold product should be within 70% of the theoretical injection volume of the machine. The required lock is calculated according to the product projection area The size of the mold force. Pay special attention to whether the distance between the columns of the machine, the mold opening stroke and the minimum mold thickness are suitable for the mold.
 
Choose human-machine dialogue and operability. Injection molding machines should make their operation and management more user-friendly. The operation should be convenient, the display should be clear, easy to understand, and clear at a glance. There are parameter selection, product quality control, and mold data storage Its automatic reproduction function of various parameters can quickly diagnose and eliminate faults, reduce material waste in the shortest time, and restore the normal operation of the system.
 
The stability, reliability, safety and service life of the machine. The stability of the machine is mostly expressed in whether the clamping mechanism and the injection molding system are running smoothly in each cycle. It works under non-impact and silent, and the noise must not exceed the industry Standards. These conditions are related to the mechanical manufacturing and assembly accuracy, and are also related to the reasonable design and structure of the toggle link. The reliability and service life are mainly reflected in the system rigidity of the clamping mechanism, which is related to the template, tie rod, and The structure, size, material and heat treatment process of the connecting rod and its pin shaft are related; the plastic warping system of the injection molding machine, such as the barrel, screw, screw head, non-return ring, and the structure and manufacturing process of the screw drive spindle, etc. These parts are the main stress and wear parts of the injection molding machine, which directly affect the service life.