Power loss vertical injection molding machine hydraulic system

Date：2014-11-03 10:13:42

Currently vertical injection molding machine is mainly divided into four categories: machine hinge vertical injection molding machine, fully hydraulic vertical injection molding machine, all-electric and hybrid-type vertical injection molding machine vertical injection molding machine. Machine hinge vertical injection molding machine using five-link mechanism having energizing and self-locking function to promote the template mold and clamping system through the proportional valve for multi-level pressure and speed control; fully hydraulic vertical injection molding machine is hydraulic clamping mechanism direct pressure clamping force evenly to make the template, the template will not occur due to uneven force deformation, ensuring consistent die each point force, capable of producing a uniform and stable product; all-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 the 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 position in the domestic vertical injection molding machine market.
         Fully hydraulic vertical injection molding machine energy consumption was largely following parts: pump energy consumption; pressure loss along the way and consume local pressure loss; heater power consumption and power consumption of the circulating cooling water pump, which pumps motor electricity accounts for the entire vertical injection molding machine with a capacity of more than 80%, followed by the loss of hydraulic pressure components along the way, so how to effectively reduce energy consumption vertical injection molding machine is very important.
A fully hydraulic vertical injection molding machine hydraulic system to improve power loss method
         Hydraulic transmission: It is based hydraulic oil as the working medium, through the power components (oil pump) the original motivation of the mechanical energy into hydraulic oil pressure can then pass control components, and then by means of the implementation of the components (hydraulic cylinder or hydraulic motor) hydraulic energy converted to mechanical energy to drive the load to achieve linear or rotary motion, and remote control through the manipulation and control components for flow regulation, adjusting power and speed of implementation of the component.
Energy 1.1 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 for each cylinder and hydraulic motor provides the necessary thrust, pressure direction and movement speed. The output power is equal to the pump motor output torque and motor speed of the product, when the system requires low flow when 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 (such as cooling) is true, so that the throttling loss of power is very large, the efficiency is very low, typically only 60% to 70%, resulting in a waste of energy, and because of the long-term full of hydraulic oil circulating through the hydraulic, mechanical parts the intense friction, resulting in high oil temperature, excessive noise and other problems, the machine also shorten life expectancy.
1.2 Use of energy-saving inverter control pump - motor
         Inverter-controlled pump - Motor fundamentally overcome the traditional vertical injection molding machine energy waste ills, when the flow system needs to change, the motor speed also followed changes, so that the metering pump discharge flow rate changes, that is, "how much needs to supply", thus saving a lot of power. Depending on the injection molding products, energy-saving rate of 20% to 70%.
         Now a brief analysis of the variable pump structure and working principle.
         Variable pump pressure and closed-loop control of the swash plate is electrically controlled by a proportional valve 2 implementation of the proportional valve control piston 4 decided by proportional to the position of the swash plate position 1, the pump displacement swash plate, control slide 3 by the valve spring (5) pre-pressing, and is always subject to a pump pressure. When the pump does not work, and the control pressure of the 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 pressure of the pump through the valve port a p is applied to the control piston 4. Adjusting the pump pressure and the spring force of the spool 5 on the equilibrium, so that the pump pressure is between 0.8 ~ 1.2MPa. The basic setting is in closed-loop control circuit does not work when implemented, controlling the proportional valve shall be borne by the system from the control panel, all of 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 input, the pressure through a pressure sensor sampling, a pump mounted on the actual value of the displacement sensor provides the pump swash plate angle to obtain the actual value of the processing by the amplifier and with the command value 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. Minimum signal generator output signal as a command valve loop control circuit values. The actual position of the spool valve body is provided by an inductive sensor 6. Valve position controller output value by the output of the amplifier output current proportional solenoid 8 decision. Once at the operating point, the ratio of the valve body 9 is held in the neutral position. If the higher-level controller is necessary to increase the inclination (increased traffic), the spool 9 for an off-center position (the control piston 4 through 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 valve movement. When the need to reduce the angle of the control channel of the piston 4 is P → A.
1.3 Application 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 efficiency of the system; and to achieve numerical ratio of backpressure control, plasticizing effect has been improved; reduce the level of pollution of the hydraulic system system failure is significantly reduced.
2 energy consumption
2.1 pressure loss along the way and consume local pressure loss
         Hydraulic oil flows through the inevitable existence of various types of hydraulic valve pressure loss and flow losses, the loss of this part of the energy account for a large proportion of the total energy loss. 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 ensure a stable flow to meet the minimum requirements, the pressure valve in case of hydraulic equipment to meet the normal work, try to get 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 points in a relatively smooth metal tube is shorter than the rubber hose section, so the total pressure loss along the way can save about 25%.
         Secondly, when a reasonable choice of hydraulic oil, hydraulic oil flow in the pipeline, the viscosity will appear, while 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 viscosity-temperature characteristic of good 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.
2.2 Consumption of other energy losses
         The energy consumption of the heater power consumption is a relatively large component, but does not represent a large power consumption of the large energy consumption, but quickly reaches the set value of the temperature representative of the desired tube. 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 (within the injection molding workshop, generally more than one vertical injection molding machines to share a single cooling water pump), this part of the energy consumption is relatively small.
3 Conclusion
         In the increasingly severe power 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 from the vertical injection molding machine capable of several major energy components consumption, and to investigate the relevant energy-saving measures, to share with you, in order to hasten vertical injection molding machine energy to get better improvement.

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