HC Plastics News: Injection molding hollow molding equipment combines the injection molding machine injection molding technology and the extrusion blow molding machine molding technology into one, and exerts the green processing performance to improve the green molding performance of the hollow molding. This paper introduces the author's innovative SZC-3150 toolbox package injection blow molding equipment, briefly describes its main green features, and points out that only innovative drive hollow molding equipment can meet and expand the "real needs" and "potential requirements" of hollow containers. ".
This section introduces the author's innovative SZC-3150 toolbox package to blow blow molding equipment, and discuss the green features of the injection molding and hollow molding injection molding hollow molding equipment and the direction and key points of the innovation drive.
The product of the kit package is characterized by thick wall, relatively small inflation, low dimensional accuracy, and thinness. The direction of green plastic innovation drive: shorten the molding cycle to improve production efficiency; increase the proportion of return materials in molding materials; improve resource recycling rate; simplify molding process and reduce energy consumption.
1. "Extrusion + Hollow Molding" Toolbox Package Greening Defects of Extrusion Blowing Hollow Molding Equipment "Extrusion + Hollow Molding" Toolbox Pack Plasticized extrusion form of extrusion blow molding equipment, low extrusion pressure, additional injection required The device can eject the melt from the storage tank to form the preform.
â—† Low productivity. After the extruded preform of the kit package is inflated, generally no cooling process is required. The formation time of the parison of the continuous extrusion die depends on the extrusion rate and takes a long time. The entire molding process is performed in order, which is disadvantageous in shortening the molding cycle, and it is difficult to achieve high productivity and high profitability.
â—† Poor adaptability to raw materials. The continuous extrusion die is suitable for processing plastics with good fluidity, and can not process mixed plastics with poor fluidity with a high proportion of recycled materials, so the space for reducing the raw material cost of the products is limited.
â—† Energy efficiency is low. Extrusion metering accuracy is lower than injection plasticizing metering accuracy, and excess extruded molten plastic reduces energy efficiency.
2.SZC-3150 toolbox package injection blow molding hollow molding equipment innovation-driven main green features
According to the traditional green tool kit, the authors squeezed the main green defects in the hollow molding equipment. The innovatively developed "injection + hollow blow molding" SZC-3150 toolbox package injection blow molding equipment, injection capacity 3150cm3, injection pressure 30MPa, plasticization The capacity is 214kg/h, the head compression ratio is 1.5~2, the die taper is 150-200, and the die has a minimum diameter of 160mm.
2.1 injection blow molding process principle
Injection blow molding is a molding method for producing large hollow containers combined with injection molding and blow molding, and is a molding method from the injection molding stage to another blow molding stage. During molding, the molten material is injected into the inner cavity of the machine head under high pressure by the injection device, and the molten material at the die is extruded under the high pressure to extrude the die. At the same time, the parison flows through the compressed air of the die core rod to pre-inflate the parison, the parison is extruded for a certain length, the lower end is sealed, the parison reaches a prescribed length, is clamped in the cavity, and is inflated and attached. The surface of the cavity is formed, and after rapid cooling, the mold is released to obtain a hollow product.
2.2 The main technical features of the green plastic innovation drive of the blow molding machine
High-speed injection can increase the extrusion rate of the preform, reduce the heat loss during the extrusion process, reduce the inflation air pressure, and achieve the purpose of energy saving; high-pressure injection makes a higher proportion of recycled material and fluidity The poor polymer material can also smoothly extrude the embryo and improve the resource utilization rate; the injection rate is higher than the extrusion rate, which can shorten the formation time of the parison and help to improve the strength of the weld seam; after the injection, it can enter immediately In the plasticizing process, the two processes of taking out the product and plasticizing are carried out simultaneously, and it is not necessary to enter the extrusion plasticizing process after the product is taken out, such as extrusion blow molding, which is advantageous for shortening the molding cycle.
The injection blow molding machine is composed of a mechanical system, an electric control system, a hydraulic and pneumatic system, a heating and cooling system, and the like. The mechanical system is mainly composed of injection plasticized parts, machine head, clamping mechanism, head lifting mechanism, etc. The layout is similar to the extrusion blow molding machine.
(1) Plasticized extrusion structure
The plasticizing extrusion of the kit extrusion blow molding machine was changed to plastic injection. The plastic injection and the arrangement of the guide columns are changed from the upper and lower parallel type of the ordinary injection molding machine to the parallel type of the same plane to reduce the height of the plastic injection part. The power source for plasticizing and injecting is the hydraulic power source of the system.
Compared with the extrusion blow molding machine, the main structure difference between the injection blow molding machine and the extrusion blow molding machine is plasticizing extrusion and machine head. The plasticizing extrusion of the extrusion blow molding machine is composed of an extruder, and the machine head is matched with the function of the extruder. The plasticizing extrusion of the injection blow molding machine is composed of an injection plasticizing device, and the machine head is matched with the function of the injection plasticizing device. The hydraulic electrical system and the structure and function of the whole machine are matched.
The plasticizing extrusion device of the injection blow molding machine is composed of a hopper, a barrel screw, an injection cylinder, a barrel heating ring and the like. The plasticizing extrusion layout takes into account the high height and large radial size of the large-scale hollow molding machine. The center height of the injection plasticizing device should be reduced as much as possible, and the axial dimension should be shortened to reduce the overall size of the machine. The injection barrel is arranged in a "┢" type through the coupling sleeve and the head. The plasticizing device achieves the quality required for the parison according to the characteristics of its own plasticizing capacity (plasticizing capacity, which is equivalent to the capacity of the storage tank of the blow molding machine head).
Since the plasticizing time of the blow molding hollow molding accounts for 60% to 80% of the molding cycle time, the plasticizing ability is as high as possible within the range of various conditions.
The low-speed large-torque hydraulic motor directly drives the screw plasticizing energy-saving mechanism. Double cylinder injection, horizontal arrangement of injection cylinder and barrel screw axis on the same level to reduce center height and shorten axial dimension. Each plasticizing stroke can reach 5.5 times of the diameter of the screw. The material enters the barrel through the hopper, and is transported and compacted along the screw groove under the action of the screw rotation. At the same time, it is plasticized into uniform under the action of screw shear heat and external conduction heat. The melt gathers on the head of the screw. Under the pressure of the melt pressure, the screw retreats while rotating, the amount of melt at the head of the screw gradually increases, the screw retreats to a predetermined stroke, and the plasticization is completed. The melt then pushes F at the high level of the screw and squeezes the melt from the coupling sleeve into the handpiece.
(2) Plasticizing screw
Injection blow molding is different from injection plasticization. The injection molding plasticized melt has a short residence time in the cylinder, and the plasticizing quality is high. The time for injection molding the plasticized melt to the injection-type embryo is plasticized by injection molding. The melt is injected into the cavity for 5 times, and the molten material is injected into the die, and the middle is again split to improve the plasticizing quality. Therefore, the plasticizing uniformity of the melt in the cylinder is relatively low, so The plasticizing capacity is mainly designed to design the screw structure, and the length to diameter ratio is 20, which can appropriately increase the groove depth of the homogenization section to improve the plasticizing ability. The plasticizing and injecting two functions are integrated into one screw, and the plasticizing stroke can take 5.5 times of the screw diameter.
(3) Coupling sleeve
The coupling sleeve is a barrel-shaped part that integrates the barrel and the machine head, and the heating coil and the device thermocouple are outsourced. There are three main functions: the transition path of the melt into the machine head; the filter installation body, if the product has special needs, can install the filter in the body cavity of the connection; feeding, each time the injection of the melt, the body cavity is still connected Filled with melt, it has a feeding effect on the parison.
(4) Fully moving cylinder
The whole shifting cylinder is an integral moving injection plasticizing device and a machine head. One function is to adjust the head to coincide with the center position of the mold parting surface. Another function is to move the handpiece to the final position in the direction of the injection device in order to install the mold and disassemble the die.
(5) machine head
The handpiece is an important device to ensure the quality of the embryo. The injection molding blow molding machine head is composed of a die switch oil cylinder and a machine head. The machine head is composed of a machine head body, a core rod, a transition plate, a split plate, a die, an adjusting screw, a heating temperature control device and the like. The biggest difference between the injection blow molding machine and the extrusion blow molding machine head: the former injection cylinder is placed on the injection plasticizing device, and the latter extrusion cylinder is placed on the machine head; the former machine head cavity is not A storage tank, the latter of which is provided with a storage tank.
In order to improve the quality of the embryo, a circular double-branch center-feeding head was developed to ensure that the pressure at each point of the embryo was consistent with the velocity of the exit die. The melt is injected into the head of the injection head under high pressure, and is divided into two horizontally flowing through the semicircular branch pipe of the annular double branch manifold, and then recombined at the center of the splitter plate, pressed into the conical split core rod, flowing through The porous transition plate enters the inner cavity, and the molten material at the die is squeezed by the pressure to push the exit molding die, and the compressed air flows through the inner passage of the mandrel into the preform to pre-inflate. This function shows that the annular double-cylinder center-feeding splitter plate ensures uniform pressure of each melt unit, and the conical split-core mandrel ensures the uniform speed of each melt unit, which guarantees the injection of the parison from these two aspects. No distortion and no deformation around.
Mold switch cylinder. Set above the machine head. Control the wall thickness of the embryo and the two functions of the switch die. The sealing form varies depending on the requirements of the molded product. If it is necessary to perform servo multi-point control on the parison, the sealing ring should be made of materials and types with small friction and responsiveness, such as grid rings and stell. If there is no need for multi-point control of the parison, such as forming toolbox, luggage, the use of ordinary type of sealing ring has met its performance requirements. The piston stroke is adjusted to achieve the purpose of adjusting the stroke of the die, that is, controlling the gap between the die and the core. The piston rod and the head are rigidly connected, and the heat of the melt in the inner cavity of the machine head is transmitted to the cylinder, and the joint is insulated and water cooled. There is a rigid connection between the die and the cylinder block, and the cylinder body relatively moves the piston. When the die is plasticized under the action of the switch cylinder, move downward to close the die; when injecting, move up and open the die. The wall thickness of the parison is controlled by adjusting the opening gap of the die; the uniformity of the circumferential wall thickness is controlled by adjusting the screw to adjust the gap of the die.
(6) Energy-saving hydraulic power drive system
It consists of an oil pump and a motor pump motor, a hydraulic component that controls the actuator, and a cooling system. Reducing the energy consumption of the hydraulic system is the key to reducing the energy consumption of the whole machine. According to the molding characteristics of the blow molding machine, the advanced technology of the hydraulic system of the injection molding machine is applied to the hydraulic system of the blow molding machine to improve performance and reduce energy consumption.
The injection molding blow molding machine's hydraulic power source uses a high-pressure small-capacity and medium-pressure large-capacity double-pump pump, and the double pump meets the requirements of rapid mold shifting and rapid injection. The small pump meets the requirements of hydraulic lifting, low speed shifting, high pressure clamping, die switch, integral movement and low speed injection. The clamping pressure is controlled by the working pressure of the small pump, so the working pressure of the small pump can be controlled to provide a suitable clamping force according to the requirements of the product to protect the mold. The reasonable combination of the double pumps can reduce the capacity of the pump and the motor and reduce the loading power of the whole machine.
For ultra-large injection blow molding machines, the hydraulic power source can be combined with multi-pump and multi-motor to provide suitable flow and pressure for each action to reduce energy consumption.
(7) Pneumatic power drive system
It consists of an air compressor, a pneumatic component that controls the execution system, and so on. The air compressor is the power source of the pneumatic system.
There are two pneumatically actuated actions of the injection blow molding machine of the molding kit: pre-blowing and mold inflation molding. The ejection can be mechanically ejected or pneumatically ejected. Mechanical ejection can save the ejection time, that is, reduce the cycle time. Product molding - mold opening - the template is retracted, hitting the mechanical ejector rod, and the product is ejected and dropped. Pneumatic actuators such as engraving, discharging, bracing, and lower blowing are set according to the requirements of the molded product.
(8) Product cooling system
The forming tool box and the luggage are composed of a freezer and related matching components, a nitrogen cooling device, etc., and the chiller device has been satisfied, and the chilled water temperature is 5 to 10 °C. For thick-walled and super-large products, it is necessary to cool the inner cavity of the hollow product to ensure the quality of the product and shorten the cooling time, and even need to use chilled water spray cooling.
(9) Electrical control system
The height of the injection blow molding machine is generally more than 2m. The injection part is located at the top of the whole machine, and the injection part needs to control more parameters: stroke, multi-stage injection speed and pressure; plasticized back pressure. For precise control and control, the injection/plasticization position uses a displacement sensor to precisely control the position of the parameter change.
The clamping part is located on the base of the whole machine. After the tool box and the bag are formed, it is usually taken out manually. Controlled parameters: stroke, low speed shifting, high speed shifting, low pressure mold, high pressure low speed mold clamping, high pressure low speed mold opening. According to this feature, the clamping part can be either a displacement sensor or an inductive switch.
Displacement control of overall movement. This function is rarely used, and the ordinary limit switch can be used. Opening and closing control of the die cylinder. Precise control is achieved with inductive switch control.
The head lift and overall movement are independent adjustments and manual control.
In order to adapt to the injection of high-speed and high-pressure extruded preforms, the strength of the core adjustment rod is increased. Optimize the core envelope flow path to increase the weld seam strength.
(10) Safety protection device
The most important thing is the cold start protection. The cold material in the machine head is not completely melted and cannot be injected. Otherwise, the inner mold or the core rod will be broken. The cold material in the barrel is not completely melted and cannot be plasticized, otherwise the screw will be broken. After the cold material in the machine head and the barrel is completely melted, the whole machine can be started to perform the molding cycle.
3.SZC-3150 toolbox package injection blow molding equipment main green features
Toolbox package injection molding examples. The molding cycle of the tool kit (shape: 410mm × 340mm × 120mm. Preform: 2000g.) has been shortened from the conventional 30s to 18s. It has become the shortest cycle time for the same type of toolbox in China, and the toolbox package with the highest proportion of the return material in the molding material. Forming Machine.
3.1 greatly reduce the color change time
There is no storage tank in the nose of the blow molding machine. The storage material is carried out in the injection barrel. The innovative development of the symmetrical ring type double-branch center-feeding head structure, the surface of each part of the machine head cavity is streamlined, shortening the color change time, about the same size Half of the color change time of the blow molding machine. At the same time, waste is reduced and social energy consumption is reduced.
3.2 type embryo quality repeatability is high
The quality of the parison depends mainly on the repeatability of the amount of plasticization. The precision of the injection plasticizing amount is determined by the plasticizing stroke precision, and the control of the plasticizing stroke precision is precise and intuitive, and can be accurately ensured. Extrusion plasticization is limited by two main factors: screw speed and plasticizing time. These two factors are subject to more interference and poor precision control, which affects the repeatability of the quality of the preform. The change of the injection speed reaches the control type of the original wall thickness, and the hydraulic drive system of the control type of the original wall thickness specially equipped by the extrusion blowing device is omitted.
3.3 injection plasticization efficiency is high
The injection screw head has a anti-reverse ring structure, and the melt return flow rate during injection is almost negligible, and the injection efficiency is extremely high. Injection plasticizing, back pressure only plays a role in regulating the quality of plasticization, and does not affect the plasticizing efficiency.
3.4 good plasticizing performance
The back pressure can be conveniently adjusted to control the plasticizing quality of the melt.
3.5 Plasticized energy consumption is low
By plasticizing the same raw material, the injection screw has a small aspect ratio and a small compression ratio with respect to the extrusion screw, so the driving torque is small, and the load power and the driving energy consumption are reduced. The injection plasticizing is axially movable, the contact surface of the screw with the molten material is gradually reduced during the plasticizing process, and the torque is gradually reduced, so the energy consumption per unit time is gradually reduced. Injection plasticizing, the barrel does not require air cooling. Injection plasticization reduces the energy consumption by about 20% from the above three aspects compared to extrusion plasticization.
3.6 high strength of melt fusion line
Improving the strength of HDPE melt-fusion line is the main subject of the design of the machine head. The most effective method is to prolong the residence time of the melt in the machine head to overcome the "elastic memory" effect of the melt and reduce the melt viscosity. Sensitivity to temperature, broadening the distribution of melt flow MWD. The injection molding of the blow molding machine and the special structure of the machine head, from the plasticized melt to the injection exit mold, after more than 5 molding cycles, the melt stays in the head cavity for more than 4 molding cycles. The molecules in the melt are re-aligned for a sufficient time, the strength of the melt fusion line is increased, and the surface quality of the parison is improved. There is no storage tank in the machine head, which greatly reduces the radial thickness of the melt in the machine head, reduces the temperature gradient of the melt radial direction, and ensures that the internal melt is not broken after the preform is extruded.
3.7 type embryo wall thickness control diversification
There are three types of wall thickness adjustment: the gap of the inner die is changed; the injection speed or the injection pressure is changed, thereby changing the injection rate of the parison, thereby changing the die expansion rate of the parison; and adjusting the pre-blowing compressed air. P, V value, to achieve the purpose of changing the wall thickness of the embryo.
3.8 Increased productivity and reduced energy consumption
The kit of the present example was molded using an extrusion blow molding machine of the same mold clamping structure, and the productivity of the injection blow molding was about 40% higher than that of the extrusion blow molding, and the energy consumption was reduced by about 30%.
Conclusion
The author introduces the innovative driving SZC-3150 toolbox package to blow the hollow molding equipment, which shows that with the continuous development of the green plastic container greening and the expansion of the green application space, only the innovative driving hollow molding equipment can meet and expand the hollow container. “Realistic needs†and “potential needsâ€. 
Editor in charge: Wang Ning 12
Aluminum Window Friction Stay,Surface Mount Hinges,Hooks And Bands Hinges,European Cabinet Hinges
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