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Application in die-casting machine with PI9000 frequency inverter

Foreword


For the die-casting products industry, its power consumption is a major part of the cost of manufacturing, and casting machine products factory is one of the major energy-consuming equipment, known as electric tiger. Thus reducing the energy consumption of casting machine industry to reduce costs, improve product competitiveness and effective way.

First, the casting industry brief

At present, most of the casting machine belongs to hydraulic casting machines, hydraulic power transmission system provided by a motor driven pump. In the process of casting cycle changes, the casting machine at different processes require different flow and pressure, must rely on the flow valve and the pressure valve to regulate different processes to be different flow and pressure. And when the load is relatively large changes, due to the dosing pumps can not adjust the output power, so the excess energy can only be consumed in the baffle, oil spills, oil temperature, it is also exacerbated by the wear of various valves, also caused oil too high, the motor noise is too large, and mechanical phenomena such as shortened life expectancy. And often in the design of the motor capacity is much higher than the actual needs, there are "big horse car" phenomenon, resulting in a lot of wasted energy. Therefore, the drive to promote the application of the casting machine, reducing energy waste is important.

Second, casting machine hydraulic system schematic overview

 

 

 

 

 

 

 

 

1, Casting machine works Overview
Fully hydraulic die casting machine is a typical cyclical work system equipment, a complete working cycle (step process) can be divided into clamping, to soups, charge injection, core pulling, mold, thimble

cooling, storage pressure, and several stages, each stage pump through the hydraulic pump motor oil to each cylinder through a series of actions to promote the transmission mechanism, each stage requires different pressure and flow. For hydraulic systems, each stage of the pressure and flow requirements of each are not the same, and pump motor power is based on its maximum load configuration during operation, while the die-casting machine, only one working cycle and charge injection pressure clamping work phase load is large, the other working stage is generally small, in the cooling process load is almost zero. For the pump motor, the casting machine process for changing load state, in the quantitative pump in the hydraulic system, the pump motor at a constant speed to provide a constant flow rate, and the working pressure and the flow rate is required by the proportional pressure valve and the proportional valve to regulate the flow rate, pressure or flow rate by adjusting the opening degree of the proportional valve to control the pressure or flow rate. The excess hydraulic fluid through the relief reflow, this process is known as high pressure shut-off, the energy loss caused by it is generally about 50%.


 

2, Casting machine energy-saving principles outlined
Learned from the die casting machine works, high-pressure shut-off pump motor energy is wasted place. I produced the die casting machine dedicated current vector inverter use this feature, according to the needs of Casting machine production process, using the inverter adjust pump motor speed, according to the die casting machine work required pressure or flow parameters and casting machine action synchronization control feedback signal proportional flow valve casting machine, proportional pressure valve to achieve automatic adjustment of pressure and flow, the effect is equivalent to quantitative pump transformed into a variable displacement pump, so that the return flow through the relief valve to minimize the pump output and the entire machine is running the required pressure and flow to match, and no pressure overflow energy loss. Drive through the feedback signal tracking the various working stages of pressure and flow changes and automatically adjust the pump motor speed. Thus, the pump motor power consumption will follow the output load changes, which can maximize the energy saving, that is economical and practical. Many factories through the transformation, has achieved remarkable economic

 

3, Casting machine power consumption
Casting machine power consumption is mainly manifested in the following sections:
1) the power consumption of the hydraulic system pump
2) power consumption of the heater
3) the power consumption of cooling water pump
In the die-casting workshop, and more generally die casting machines share a cooling water pump, hydraulic pump motor power which accounts for the entire die casting machine more than 80% of electricity consumption, so reducing its power consumption is the key to saving Casting machine.

Third, the casting process description
And stripping die casting machine, hydraulic system for the lower mold and shorter; while injection, packing, cooling system for the oil pressure is higher, and longer time, usually a duty cycle of 40 % ~ 60%. The duration of each stage and the relevant workpiece; intermittent duration is also relevant to the situation with the workpiece can sometimes not intermittent. If the injection screw with a motor-driven hydraulic oil, hydraulic injection system will be higher. Workpiece weight Casting machine, from tens of grams to tens of thousands of grams of dollars. Therefore, there are small, medium and large-scale Casting machine of the points, processing tens of grams of small parts and the number of kilograms of large workpiece machining cycle time is not the same, that is, on the same die-casting machines, machining workpieces of different materials, each section of the process flow pressure and time are also required to be changed.

 

 

Fourth, energy efficiency estimates
1, the basis for this assessment:
Estimated 70 percent efficiency motors, electrical energy-saving rate of 35% -45% estimate, transformation of the total power 22KW × 5 sets = 110KW; electricity price 0.7 yuan / kWh, working 24 hours a day, working 30 days a month, the annual work 12 months, the operation rate of 85%.
Ideal energy-saving rate = {1 - (30/50) 3} * 100% = (1-0.216) * 100% = 78.4%
According to our estimates conservatively saving rate should be about 45%.
2, benefit assessment:
Daily electricity savings = motor efficiency ×motor power × saving rate × 24 hours X operation rate
= 110KW × 70% × 40% × 24H × 85% = 628.3 °
Monthly electricity savings = 628.3 × 30 × 0.7 = 13194.7 RMB
Annual electricity savings = 13194.7 × 12 = 158336.4 RMB
3, the total cost of investment:
Total investment cost = motor power × 1.2 times × Unit Price = 110KW × 1.2 × 1000 RMB / KW = 132000 RMB
4, the payback period:
Payback period = investment cost ÷ month electricity savings = 132,000 RMB ÷ 13194.7 RMB = 10 months

 

Fifth, the selection of equipment and routine maintenance
Selection Powtran PI9000 series high performance current vector inverter, die-casting machine according to the main pump motor power matching the same power can be.
Drive internal core components are imported components to ensure the quality of the inverter under normal use and in life.
An inverter cabinet cooling fan and cooling fan average life expectancy of two years, please note that daily cleaning to prevent dust clogging.
2, the drive filtering electrolytic capacitor life under normal use, 3-5 years, please note change of contact.
3, the installation site should be kept away from moisture, dust, metal dust is strictly prohibited.

 

Sixth, after the transformation effect
High saving rate: transformation, quantitative pump into energy saving variable pump, die-casting machine hydraulic system and basic operation of the machine matches the required power, no high-pressure throttling overflow energy loss, saving rate of 20% 60%.
High efficiency: transformation of the former power factor is generally 0.5 to 0.8, after the transformation of up to 0.96 or more, it can significantly improve the power factor, reduce reactive current, which reduces line losses. The power supply equipment, then played a compatibilization role.
High reliability: Retain the original casting machine control mode and do the same oil reserve, failure timely warning, overvoltage, overcurrent, overload, overtemperature, undervoltage and short to ground and other protection, but also effectively protect the pump motor. The use of electricity / energy saving control mode, once the failure does not affect production.
Mechanical life, improve the environment: soft start to reduce power clamping motion to extend the life of equipment and tooling to reduce noise. Improve the working environment, significantly reducing system heat, oil stability, cooling water can save more than 30%. Extend the service life of the seal assembly, reducing maintenance downtime opportunity to save a lot of maintenance costs.

 

Conclusion
Saving is to create efficient, energy-saving transformation throughout the power system after reaching an investment in long-term benefit. The saving transformation in reducing tariffs, but also for the die casting machines provide excellent security protection, will help to protect the motor, electronic components, such as the switching element equipment life, can also play a role in motor soft start to reduce equipment investment costs, maintenance costs, improve production efficiency, to create enterprise efficiency. Enhance market competitiveness.

 


 

 

Date:2013-09-25 【Print】  【Back