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Improving the energy efficiency of vertical injection molding machine

Mar. 17, 2020

Currently vertical injection molding machine is mainly divided into four categories: machine hinge vertical injection molding machine, hydraulic type vertical injection molding machine, fully electric and hybrid-type vertical injection molding machine vertical injection molding machine. Machine hinge vertical injection molding machine using five-link mechanism has energizing and self-locking feature to promote template mold and clamping system by proportional valve for multi-stage pressure and speed control; fully hydraulic vertical injection molding machine is direct hydraulic clamping pressure clamping mechanism, so that force uniform template, the template will not occur due to uneven force deformation, stress points ensure consistent mold, can produce uniform and stable products; fully electric vertical injection machine to save energy, precision and other advantages by widespread concern in the industry, although fast, precise control and power, but the high price, so many customers prohibitive; hydraulic - electric hybrid all-electric injection molding machine has the advantage of both injection molding machine, retaining the hydro-mechanical properties of the injection molding machine. The fully hydraulic vertical injection molding machine due to the high cost and high control precision, will become the dominant domestic vertical injection molding machine market.

Fully hydraulic vertical injection molding machine energy consumption was largely following sections: pump energy consumption; pressure loss along the way and local pressure loss consumed; heater power consumption and circulating cooling water pump power consumption, which pump motor electricity accounts for the entire vertical injection molding machine with a capacity of more than 80 percent, followed by the loss of hydraulic pressure components along the way, so how to effectively reduce the energy consumption of vertical injection molding machine is very important.

An energy consumption

There is the inevitable pressure loss along the way when 1.1 and local pressure loss consume all types of hydraulic valves hydraulic oil flows through the pressure loss and flow losses, the loss of this part of the energy account for a large proportion of the total energy losses. Therefore, a reasonable choice of hydraulic components, the pressure adjustment valve is also an important aspect of reducing the power loss.

Flow valve flow adjustment range by selecting the system and to ensure a stable flow to meet the minimum requirements, the pressure valve in the case of hydraulic equipment to meet the normal work, try to take a lower pressure. In length, velocity, tube through the same situation, save 16% smooth metal pipe pressure loss along the way than the rubber hose, between the same two smooth metal tube is relatively shorter than the rubber hose section, so the total pressure loss along the way can save about 25%.

Secondly, when the rational choice of hydraulic oil, hydraulic oil flow in the pipeline, the viscosity will appear, and when the viscosity is too high, will have a greater internal friction, resulting in heating oil, while increasing oil flow resistance. When the viscosity is too low, could easily lead to leaks, will reduce the volumetric efficiency of the system, therefore, generally select the appropriate viscosity and good viscosity-temperature characteristics of the oil. Further, when the oil flow in the pipe when there is a pressure loss along the way, and local pressure loss, and therefore the design of the pipe line as short as possible, while reducing the bending.

1.2 Other energy loss energy consumption of the heater power consumption is a relatively large component, however, does not represent a large power consumption of large energy consumption, but representatives reach their setpoint temperature tube required. Therefore, energy conservation is to protect the main heater insulation cover, protective cover bottom temperature, convection and radiation heat loss rate will reduce heat loss also reduced, but also reduce the risk of injury Shuo. In addition, to avoid the fan blowing tube scope to reduce forced convective heat loss. Circulating cooling water pump power consumption (in the injection molding workshop, usually more than one vertical injection molding machines to share a single cooling water pump), this part of the energy consumption is relatively small.

2 full hydraulic vertical injection molding machine hydraulic system to improve power loss method

Hydraulic transmission: It is based on the hydraulic oil as the working medium, through the power components (oil pump) the original motivation of mechanical energy into hydraulic oil pressure can, and then through the control components, and then by means of the implementation of the components (hydraulic cylinder or hydraulic motor) hydraulic energy is converted to mechanical energy to drive the load to achieve the linear or rotary motion, and by manipulation of the remote control unit for flow regulation, and adjust the force and speed of execution components.

Energy 2.1 conventional hydraulic-driven consumption of vertical injection molding machine

Vertical injection molding machine hydraulic drive required at all stages of the injection molding pressure and flow are changing, when the oil needs changing vertical injection molding machine, located in the pump outlet by proportional flow valves and proportional pressure relief valve to adjust the load pressure and flow, providing all cylinders and hydraulic motors required thrust, pressure, direction and speed. The output power is equal to the pump motor output torque and motor speed of the product, when the system requires low flow, the pump motor output power constant, excess hydraulic oil back into the tank through a proportional valve and pressure relief valve, even if empty load (cooling), too, so that the throttling loss of power is very large, inefficient, generally only 60% to 70%, resulting in a waste of energy, and because of the long-term full of hydraulic oil circulating through the hydraulic parts, mechanical parts intense friction, resulting in high oil temperature, excessive noise and other problems, machine life is also shortened.

2.2 Use of energy-saving inverter control pump - motor

Inverter control pump - motor overcome a fundamental traditional vertical injection molding machine energy waste ills, when the flow system needs to change, the motor speed also followed changes, so that the quantitative pump discharge flow rate changes, that is, "how much needed supply", thus saving a lot of energy. Depending on the injection molding products, energy-saving rate of 20% to 70% and now the structure and working principle brief analysis of variable displacement pump variable pump pressure closed-loop control and the swash plate angle is electrically controlled by a proportional valve 2 implementation, the proportional valve by controlling the position of the piston 4 is proportional to determine the position of the swash plate 1, the pump displacement swash plate, the control slide valve 3 pre-pressed by the spring 5, and always by the pump pressure.

When the pump is not working, and the pressure control system is zero, due to the action of the spring 5, the swash plate is maintained at + 100% position, when the pump is started as the proportional solenoid valve 8 is energized, the system is switched to zero stroke pressure in this case the slide valve 9 is pushed by the spring 10 to the initial position, when the pump pressure p is applied to the through port a on the control piston 4.

Force pump pressure regulating slide valve spring 5 on equilibrium, the pump pressure between 0.8 ~ 1.2MpA. The basic setting is in closed-loop control circuit does not work when implemented, control of the proportional valve shall be borne by the system from the control panel, all the variables used to control signals required by the pump control panel to deal with, respectively, the control board the actual value of the pressure and the inclination of the swash plate command values for the input pressure of the sample through a pressure sensor mounted on the pump displacement sensor provides a pump swash plate angle actual value, the actual value obtained by the processing and the instruction value amplifier comparing the minimum signal generator will automatically ensure that only the selected control function at the desired operating point.

Therefore, system parameters (pressure, inclination or power) can be accurately controlled, and the other two parameters below a given command value. The minimum output signal as a command signal generator circuit, a valve control loop values. The actual position of the spool valve body is provided by an inductive sensor 6. Output value valve position controller output via the output of the amplifier, the decision proportional solenoid current 8. Upon reaching the operating point, the ratio of the valve body 9 is held in the intermediate position. If the higher-level controller is necessary to increase the inclination (increased traffic), the spool 9 need to deviate from the middle position (the control piston 4 through the valve port A → T), until the angle reaches the desired value. By increasing the proportional solenoid current eight to overcome the force of the spring 10 so that the spool moves. When the need to reduce the inclination angle, the control channel of the piston 4 is p → A.

Application 2.3 proportional variable pump system so that the entire hydraulic vertical injection molding machine hydraulic system to reduce fever, extend the life of hydraulic components; reduce energy consumption, improve system efficiency; and to achieve numerical proportion of backpressure control, improved plasticizing effect ; reduce the level of pollution of hydraulic systems, system failures significantly reduced.

3 Conclusion

In an increasingly serious energy supply now, energy is undoubtedly one of the more important topics, vertical injection molding machine energy consumption is relatively large, it is imperative to saving, the paper mainly vertical injection molding machine can be from several major energy components consumption, and to investigate the relevant energy-saving measures, and to share what trends vertical injection molding machine to get better to improve energy efficiency.

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