Development and application of the hottest large p

2022-08-17
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Development and application of large pallet injection molding machine

I. preface

large pallet injection molding parts are new highlights in the research and development of the injection molding industry at home and abroad. At present, injection molding machines processing large pallet injection molded parts at home and abroad generally have many consumables and heavy weight; Large installed capacity; High energy consumption of processed products; The cost of molded products is high. These, to a certain extent, hinder the development of large pallet injection molded parts. In view of the above situation, this project will develop a new large-scale pallet injection molding machine that greatly reduces the consumption of consumables and molding energy consumption for the whole machine manufacturing, so that users can afford to buy and use it, and can quickly produce good economic benefits to meet the needs of the society

II. Basic principle

the large tray plastic injection molding machine of this project is guided by the innovative polymer material molding process, and the core technology is multi-point composite injection molding, which can be used for structural microporous injection molding and ordinary solid injection molding. The principle of multi-point composite injection technology is to optimize the molding path in the injection process, which enables the molding of materials with poor fluidity (plastic recycling materials and materials with small melt index). The large pallet plastic injection molding machine of this project has made significant improvements to the mold closing part of the machine, the injection system, the product taking manipulator, etc. with the innovative large molding process, and the process technology is at the international leading level

III. key technical content

1. Innovative multi-point composite injection molding

the multi-point composite injection molding of this project is the key to the large tray molding process, and at the same time, it reduces the length ratio of the molding channel. According to this process, the injection pressure required in the injection process is reduced, the average pressure of the mold cavity is reduced, and the mold locking force to ensure molding is also reduced. For example: Processing 1.2m × l.0m × 0.16m plastic tray, set the length ratio of molding channel to be less than 1:50, when structural micropore injection (HDPE) is carried out, the injection pressure is 30MPa, the average pressure of mold cavity is 6.5MPa, and the mold locking force is 7800kn. When ordinary solid injection (HDPE) is carried out, the injection pressure is 51mpa, the average pressure of the mold cavity is 9.5Mpa, and the mold locking force is 11400kn. Based on this process, the machine parameters are determined: the maximum injection pressure is 80MPa, the injection rate is 5500cm3/s, and the maximum clamping force is 23400kn

at present, most of the "plastic tray machines" at home and abroad are single point injection, the model flow length ratio is 1:150, the machine injection pressure is 110MPa, the average pressure of the mold cavity is 20 ~ 30MPa, and the mold locking force is 30000kN. In order to solve the problem of single shooting point and long molding process, some enterprises use hot runner in the mold when designing the mold. The heating and control technology of hot runner in the mold still depends on imports, which increases the cost of the mold. The "single shot point and large injection process" can only be produced with raw materials, and the multi-point composite injection of the technical scheme of this project can solve the above problems. The structural microporous composite injection process of the large project tray plastic injection molding machine can be made of aluminum alloy because the average pressure of the mold cavity is greatly reduced, which reduces the mold processing cost

2. Process improvement determines the quality of processing materials and products

the large pallet plastic injection molding machine of this project is controlled by PLC to complete the whole injection process of super large products in an instant

process improvement makes polymer materials with poor fluidity (waste plastic recycling materials, materials with small melt index) easy to process and shape, so this machine can process recycled plastics. The multi-point composite injection and the process segmentation of the injection process make the stress distribution of the products uniform and the quality of the molded products improved. Machine processing adaptability is strong, so the machine can be produced with raw materials; Mixed production of raw materials and recycled materials; All materials are returned for production

the large tray plastic injection molding machine of this project can inject 4000g of molten material at each injection point, and the process state is reasonable. In the traditional large-scale injection molding machine, a single nozzle instantly shoots more than 25kg of material, and the nozzle partially exceeds the combustion temperature of the material, resulting in black locks at the gate of the product and deterioration of product performance

3. Innovative direct mold locking mechanism and machine weight

the mold locking force of the large pallet plastic injection molding machine in this project is not borne by the machine frame, but directly locked by the symmetrical mold locking mechanism

due to the direct application of mold locking technology, the plastic injection molding weight of 40000 large pallets in this project is only 38 tons

4. Super large injection molding machine with continuous and uninterrupted plasticization

in the plasticization process of large tray plastic injection molding of the project, the screw always operates. The realization of this process is due to the additional design of the plasticizing cylinder and distributor, and the process is accurately controlled by PLC. "Continuous and uninterrupted pre molding" makes the processing efficiency of this super large machine higher than that of the traditional injection molding machine. The diameter of the plasticizing screw is only 110mm, and the installed plasticizing power is 45KW

the realization of this process is because the machine is additionally designed with storage cylinders, distributors, system safety discharge valves, and the process is controlled by PLC. This method is an effective measure to reduce the energy consumption of the machine and reduce the manufacturing cost of the screw plastic part of the machine. Therefore, the processing efficiency of this machine is higher than that of the traditional injection molding machine. This technology has no precedent at home and abroad

5. Large injection molding process of "horizontal striking and vertical pulling" and automatic taking out products (manipulator)

this project is a horizontal injection device, with vertical mold closing and locking. When opening the mold, the "product taking car" enters, and the products fall on the "product taking car", and the product taking car (simple manipulator) automatically returns to complete automatic production

6. Advanced technology has greatly reduced the energy consumption of the machine

the large pallet plastic injection molding process of this project is completely different from the traditional injection molding process. The process action is complex, the control accuracy is high, and the process performance is more reliable, safe and convenient to operate

7. The market situation of testing instruments such as high reliable machine performance tensile testing machine is also greatly optimistic

the main parts of the mechanical part of the large pallet plastic injection molding machine of this project are designed for stress analysis, which conforms to the industrial technical specifications and standardization, strict processing technology and quality assurance. The components used in the electric control and hydraulic station of the machine are international brand products, such as Siemens PLC, Omron proximity sensor, Mitsubishi variable frequency governor, Rexroth oil pump, control valve, Vickers cartridge valve, honger hydraulic seal, etc., to ensure high and reliable machine performance

8. Highly reliable machine safety performance

a) the hydraulic system is equipped with safety valve to overflow under overpressure

b) overpressure alarm and emergency stop of hydraulic system

c use layer control strategy to implement technology, etc. according to his point of view) system safety discharge valve, molten materials can be discharged automatically

d) the rear position of the injection cylinder alarms and the plasticizer stops

e) the rear position of the storage cylinder alarms and the plasticizer stops

f) manual operation, the mold will automatically rise and release the constraint of the press, no matter whether the machine is working or stopped

g) the symmetrical toothed brake ensures that the mold can be reliably locked at any position without slipping

h) reliable hood protection and safety door system protection

i) the machine is repeatedly grounded

j) set 5 emergency stop buttons

IV. technological innovation

1. Multi point composite injection molding technology, and the convertible technology between structural microporous injection and ordinary solid injection

the innovative multi-point composite injection molding process of the large pallet plastic injection molding machine of this project can carry out structural microporous injection molding, and can be easily converted into ordinary solid injection molding. Multi point composite injection optimizes the molding path. It can process and recycle waste plastics and materials with small melt index. The large pallet plastic injection molding machine of this project has gone out of the misunderstanding of "simply magnifying the traditional single injection point injection molding machine to create a large injection molding machine". The structural micropore injection molding process can improve the product stress, save materials and improve the product stiffness; Ordinary solid injection molding, each point handle can be broken at the same time, and the injection molding result is the same as that of ordinary solid single point injection molding

2. Direct locking technology of the mold

direct locking technology of the mold releases the huge clamping force of the injection molding machine frame, and greatly reduces the volume and weight of the injection molding machine. The problem of high cost of large-scale injection molding machine has been fundamentally solved

large moulds are installed vertically, and the force of the moulds is reasonable, so as to avoid the accidents caused by the displacement of the large moulds installed on the horizontal mainframe during the operation of the machine

3. Simple product taking manipulator technology

this machine opens the mold vertically. When opening the mold, the product taking car equipped with wooden brackets automatically enters the mold according to the process sequence, and the products fall on the product taking car. Then, the car automatically retreats to its original position to complete the full-automatic process. At present, large horizontal injection molding machines at home and abroad need to purchase expensive manipulator equipment. The cost of the two technical schemes is very different. Obviously, this technology is simple and practical, and is more suitable for "plastic pallet machine". This technology has no precedent at home and abroad

4. Intelligent mechanical technology and energy-saving mechanical technology

the control core of KH super large plastic injection molding machine is PLC and expansion module. The control software instructions compiled by ourselves make the machine produce automatically, display faults and alarm. PLC is equipped with a communication port, which can accept external instructions, check the operation process and remote fault treatment, and adapt to the full automatic control requirements of "unmanned workshop"

this machine uses the accumulator group as the auxiliary active power source, and the PLC reasonably arranges the loading time of each process. Combined with multi-point composite injection, the injection pressure is reduced, the mold locking technology directly reduces the energy consumption of the mold locking, and the "non-stop plasticizing" technology reduces the screw power, so that the energy consumption of this machine is only 50% of that of the same model

5. Unique safety of the process

this machine opens the mold vertically, and the products fall on the product taking manipulator, and the process is unattended. When the traditional horizontal large-scale injection molding machine is opened, the operator enters the machine to take out the products (some manufacturers do not buy expensive manipulator), which is a dangerous operation

6. Hot cylinder sealing technology

kh super large plastic injection molding machine hot cylinder sealing technology comes from the automotive industry. The sealing of the injection cylinder and storage cylinder of the machine is multi-channel rare earth alloy cast iron piston ring group, the design pressure resistance is 200MPa and 20MPa respectively, and the operating life is 4x106m

7. Modular combination

with the hydraulic interface as the boundary point, it is divided into several modules, which can be installed with a 5-ton crane, transported with an ordinary truck, and the plant is an ordinary plant

8. Process control of recycled waste plastics

according to the production practice in the R & D stage of the project, the processing and recycling of waste plastics: first, there must be a guarantee of machine processing capacity; Second, the "pre process design" should be implemented for the return processing

"pre process design" content: 1 Understand the needs of users in detail. 2. Master the material quality and category of the source of this batch of plastic recycling. 3. Carry out necessary process test. 4. Conduct characterization test and inspection, and formulate detailed process documents according to the production batch to guide production

9. The application field of thermoplastic large-scale molding is expanded

this project has carried out major reforms in the mold closing part, injection part, and live manipulator of the traditional injection molding machine, so as to make a major breakthrough in the development of this international topic and super mainframe. It is also possible to inject one or two hundred kilograms of thermoplastic parts at a time. Such as processing Railway "plastic sleepers" with waste HDPE, super large plastic fan blades for wind power generation, automobile injection molded shells, plastic isolation piers for highways, large sealed containers for military industry, etc.

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