Composition, principle and development of vertical injection molding machine

The injection molding machine is a special equipment that combines the thermal processing characteristics of plastics and the principle of metal melting and die casting.

1. Working principle of vertical injection molding machine

The working principle of the injection molding machine is similar to the syringe used for injection. It uses the thrust of the screw (or plunger) to inject the plasticized plastic in the molten state (that is, the viscous fluid state) into the closed mold cavity. The process of obtaining products after curing and shaping.

2. the composition of the vertical injection molding machine

Vertical injection molding machine is usually composed of injection system, clamping system, hydraulic transmission system, electrical control system, lubrication system, heating and cooling system, safety monitoring system, etc.

(1) Injection system

The injection system is one of the most important components of the injection molding machine. Generally, there are three main types: plunger type, screw type, and screw pre-plastic plunger injection type. The screw type is currently the most widely used. Its function is that in a cycle of the plastic injection machine, a certain amount of plastic can be heated and plasticized within a specified time, and the molten plastic can be injected into the pet preform mold cavity through a screw under a certain pressure and speed.

(2) Mold clamping system

The function of the clamping system is to ensure that the mold is closed, opened and ejected. At the same time, after the injection mold is closed, sufficient clamping force is provided to the mold to resist the cavity pressure generated by the molten plastic entering the mold cavity, and to prevent the mold from opening, resulting in a bad status of the product. The composition of the mold clamping system: The mold clamping system is mainly composed of a mold clamping device, a mold adjustment mechanism, an ejection mechanism, a front and rear fixed template, a movable template, a mold clamping cylinder and a safety protection mechanism.

(3) Hydraulic system

The function of the hydraulic transmission system is to realize the injection molding machine to provide power according to the various actions required by the process, and to meet the requirements of the pressure, speed, temperature, etc. required by each part of the injection molding machine. It is mainly composed of various hydraulic components and hydraulic auxiliary components, among which the oil pump and the motor are the power source of the injection molding machine. Various valves control the oil pressure and flow rate to meet the requirements of the injection molding process.

(4) Electrical control system

The electrical control system and hydraulic system are reasonably coordinated to realize the process requirements (pressure, temperature, speed, time) and various program actions of the injection machine. Mainly composed of electrical appliances, electronic components, meters, heaters, sensors, etc. There are generally four control modes, manual, semi-automatic, fully automatic, and adjustment.

(5) Heating/cooling system

The heating system is used to heat the barrel and the injection nozzle. The barrel of the injection molding machine generally uses an electric heating ring as a heating device, which is installed on the outside of the barrel and is detected in sections with a thermocouple. The heat conducts heat conduction through the cylinder wall to provide a heat source for the plasticization of the material; the cooling system is mainly used to cool the oil temperature. Excessive oil temperature will cause a variety of faults, so the oil temperature must be controlled. The other location that needs to be cooled is near the feeding port of the feed pipe to prevent the raw material from melting at the feeding port, causing the raw material to fail to be fed normally.

(6) Lubrication system

The lubrication system is a circuit that provides lubrication conditions for the relative moving parts of the injection molding machine's movable template, plastic mould adjustment device, and connecting rod hinge, so as to reduce energy consumption and increase the life of parts. Lubrication can be regular manual lubrication or Automatic electric lubrication;

(7) Security protection and monitoring system

The safety device of the injection molding machine is mainly used to protect the safety of people and machines. It is mainly composed of safety doors, hydraulic valves, limit switches, photoelectric detection elements, etc., to achieve electrical-mechanical-hydraulic interlock protection. The monitoring system mainly monitors the oil temperature, material temperature, system overload, and process and equipment failures of the injection molding machine, and indicates or alarms when abnormal conditions are found.

Due to the increasing demand for injection products in industries such as automobiles, household appliances, and food, the development and improvement of injection molding technology is promoted. Among plastic processed products, 83% use injection molding, and the output of injection molding machines is increasing year by year, accounting for the largest proportion of plastic machinery.

The development trend of vertical injection molding machines can be summarized as follows:

1. The special requirements of injection molding machines are often due to products of different shapes and the price of this product.

For example, in terms of products, some of them are embedded, and some are not embedded, and some are single-color, two-color and some; from plastic varieties, some thermoplastics, and some of them are thermoset plastics. Therefore, special developments and special injection machines are suitable for users, have the characteristics of high performance and price ratio, technology-intensive and simplified structure.

2. The opening and closing speed of the mold with high speed, efficiency and precision. The opening and closing speed of the mold has increased from 20-30 mm/min to 40-50 mm/min, some even 60 mm/min. Injection speed, from 100mm/450mm/s, injection speed of 600mm/s for small and medium injection molding machines is not uncommon, and some can reach 900mm/s.

Small and medium-sized injection molding machines, while large and super large are developing even giant and micro injection molding machines. 40 mn, 50 mn, locked lidamycin and even large injection machines came out. Locked 50 mn injection machine made in the original West Germany, injected 24.5 kg, 140-370 mpa injection pressure. Japanese name Machinery manufactures large injection molding machines with a clamping force of 120 Mn. At present, ordinary precision, precision and ultra-precision injection molding machines have reached 0.02-0.05 mm, 0.01-0.02 mm, and less than 0.001 mm.

3. Automated production is an important way to ensure product quality, increase productivity, reduce labor intensity, improve working conditions, make full use of equipment, and reduce costs. At present, many new control devices are used, such as programmable logic controllers (PLC) to replace traditional relays. Programmer control. It works reliably, and the program can be modified flexibly. Microcomputers have been used for process control, process parameters of injection machines.

This new control method is very important for forming precision products. It can automatically adjust molding conditions and ensure product size and quality. General product production machines, product packaging other than production process testing will also be automatically performed. Safety device, to ensure the safety of equipment, not only can be automated, but also can be centralized management, to achieve unmanned operation.

4. The design of other mechanical structures uses advanced methods, concepts and means, toggle lever clamping methods and direct pressure, to improve the clamping mechanism, and form a series of standardization; the appearance and shape of the main machine are optimized for design, noise reduction, injection machines and auxiliary equipment The modularization of standardization, serialization and injection machines, the development of environmentally friendly injection machines and others have led to the attention of injection machine manufacturers.

With the continuous acceleration of the domestic automation process, I believe that my country's injection molding machine industry will soon be technologically upgraded and transformed, and it will be improved from the technical level, and the injection molding machine is also just around the corner.