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China is a big shoe manufacturing country in the world. There are more than 20,000 shoe-making enterprises. Among them, Fujian is an important plastic shoe-making base in the country. The annual output and export of shoes are among the best. Quanzhou has introduced more than 1,000 shoe-making lines, Jinjiang. The city is a famous "Chinese shoe capital". It has professional manufacturers from leather, shoe materials, chemical raw materials and digital molds. Now it has more than 3,000 shoe production and management companies with an annual output of more than 700 million pairs...
The power-limiting brake has seriously affected the normal production of enterprises. From January to July this year, the increase in the cost of plastics has made the competition in China's plastics manufacturing industry increasingly fierce. As an important means for enterprises to increase efficiency, reduce consumption, reduce operating costs and improve competitiveness, energy conservation has become particularly meaningful and gradually recognized and accepted by people.
2 Working principle of automatic disc type Plastic Injection Molding machine
As we all know, there are a large number of successful cases of frequency conversion energy-saving transformation of horizontal Injection Molding machines in China. The automatic disc type plastic injection molding machine of the shoe-making enterprise is one of the main common electric equipment in the shoe-making enterprise, and it is called the electric tiger. China is a big shoe-making country, and there are a large number of shoe-making equipment. At present, there are relatively few units involved in energy-saving renovation. The main reason is that people are not familiar with the working principle of the automatic disc-type plastic injection molding machine.
2.1 Mechanical characteristics of fully automatic disc type plastic injection molding machine (hereinafter referred to as: disc machine)
1) This machine is dedicated to the production of all kinds of high-grade monochrome, two-color and three-color sports shoes, casual shoes soles, boys and girls soles and other products.
2) The raw materials are suitable for the production of various thermoplastic materials such as foam, such as PVC, TPR, and the like.
3) This machine is controlled by computer program (single chip microcomputer, PLC). The main and auxiliary machines are controlled accurately, easy to operate and easy to maintain.
2.2 Comparison of disc machine and traditional horizontal injection molding machine
1) Hydraulic motor
The oil pumps for horizontal injection molding machines and disc machines are all quantitative pumps. During the injection molding process, the pressure of the oil pump changes frequently. The traditional treatment method of the low pressure maintenance process is to release the pressure through the proportional valve, and the motor has been running at full speed under the power frequency. The waste of electricity is very serious.
2) According to the model of the disc machine, it is divided into monochrome machine, two-color machine, three-color machine and other models.
The monochrome machine has only one main unit, similar to the horizontal injection molding machine.
The two-color machine has a main unit and a sub-machine. The auxiliary machine is responsible for the action of shooting glue, melting glue, upper mold, lower mold, etc. The main machine includes the action of the auxiliary machine, and an additional rotation of the disk realizes the movement and positioning of the mold. The tricolor machine has a main unit and two sub-machines.
3) Number of molds
Horizontal injection molding machines generally only have one set of molds in operation, and the production process needs to be changed when the mold is changed.
The disc machine is different according to the model, and the number of molds is also different. Generally, there are 18, 20, 24, and 30 sets of molds. According to the production process, through the control panel, set whether the mode position is valid or not. Such as: TY-322 model, 24 stations (24 molds can be installed), all or part of the mold can be flexibly selected as effective mold position during production). When the disc machine is working, the large turntable performs a high-speed clockwise rotation operation, and the PLC or the single-chip microcomputer performs the calculation of the program. When only the valid mold position is detected, when the PLC or the single-chip microcomputer scans the deceleration signal, the turntable starts to decelerate. When the positioning signal is reached, the turntable is accurately positioned. Otherwise, if the effective mode is not detected, the large turntable is rotated to the next effective mode. The horizontal injection molding machine performs the relevant action as long as there is a mode-locking or mold-opening signal.
4) Pressure adjustment method
The pressure adjustment methods of the horizontal injection molding machine and the disc machine are all pressure proportional control methods, but the pressure of each mold material of the disc machine (more molds) can be independently set by the control panel, which is suitable for the manufacture of different injection quantities. . The horizontal injection molding machine produces each product with the same parameters.
5) Working mode of the mold
When the horizontal injection molding machine is working, the fixed mold is not moving. Only the movable mold performs left and right clamping or mold opening when there is a command, and moves linearly from left to right. When the disc machine is working, the fixed mold and the movable mold are moved and positioned by the large turntable. When there is a mold clamping and mold opening command, the cylinder performs a rising or falling action. When taking the product, the operator manually opens the movable mold and takes out the product.
6) Disc (turntable)
The fully automatic disc type plastic injection molding machine is named for its round shape, which is referred to as a disc machine (sole machine). Several aliquots were equally divided on the disc. For example, TY-322 is equally divided into 24 modules. If neither the master nor the slave detects a valid mode, and both the master and the slave are in the open mode, the PLC or the microcontroller issues an instruction, and the disk is pressurized by the host to perform high-speed rotation. The system automatically detects the effective mold position, and the disc is accurately positioned after deceleration.
7) Cooling method
Conventional horizontal injection molding machines have the concept of "cooling time" with a cooling water cycle installed to protect the mold and product from cooling.
The disc machine is different. It does not have a cooling water circulation system. After the product is formed, the turntable of the disc machine itself is in a rotating state or standby state for a period of time. In addition, there are several cooling fans installed on the machine, and the mold and product are cooled. .
2.3 Working principle of the disc machine
During the injection molding process of the disc machine, the actions of clamping, projecting, melting, opening, and slow speed of the disc are different. The requirements for speed and pressure are different. They are set by the proportional value on the control panel. For example, P1 sets the mold pressure, P2 sets the shot pressure, P3 sets the shot secondary pressure, and P4 sets the feed pressure. When the flow pressure demand of the disc machine changes, the proportional pressure valve (relieving valve) provided at the outlet of the oil pump adjusts the load pressure and flow rate, and overflows the excess oil to the tank.
The monochrome disc machine has only one main machine, which mainly provides pressure to the system, completes the glue melting action and the mold clamping opening action, and additionally controls a turntable system to complete the movement and positioning of the mold.
The two-color machine has both a host and a slave. They are mainly composed of heating, injection molding, melting system, and clamping system. The tri-color machine is similar to the two-color machine. It has a main unit and two sub-machines. The main unit is responsible for the rotation and positioning of the disc.
The disc machine is divided into two parts: manual operation and automatic operation.
When running manually, the operator must provide the appropriate command and the disc will complete the corresponding action. Such as injection glue, melt glue, upper mold, lower mold, disc rotation and other actions.
During automatic operation, each mold position is selected. After the feed pressure and time are set and the temperature of the material tube has been reached, the main oil pump is started, and the manual and automatic unlocking is switched to the automatic position. Press the auto start button once. Automatic steps are available.
1) If the mold position is used now, press the auto start button and the feed amount is the mold set amount. If the feed does not reach the set amount, there is a mode-locking action. Only the fast mode-locking action is allowed, and the slow mode-locking action is only required after the feed reaches the set amount. After the mold clamping is stopped, the shot and mold opening action are performed.
2) If the mold position is not used now, press the auto start button, the disc will run to the next used mold position, and the feed amount of the feed will arrive, and the following set of the used mold position will be executed. Material action, after the position of the turntable, quick mode-locking (set by time), stop timing, and arrive at the time of feeding, perform slow mode-locking, and execute the shot and mold opening action after the mold-locking stops.
3) When the main and auxiliary machines are used at the same time, the automatic operation of the main and auxiliary machines must be completed until the mold is opened, and the disc will run and rotate to the next use mode.
4) When the turntable is paused before the "slow speed point" of the disc, the disc will be detected at the "slow speed point" and slow down until the positioning stops. If the mold position is used, after the positioning, the mold action will be done until the mold is opened. The turntable does not operate, but the feed action will perform the feed of the next use mode, and the disc will be released (clockwise rotation) and the disc will move to the next mold position. If the mode is not used, the disc is positioned in the most recent mode until the dial is released and moves to the next mode.
5) In the automatic operation, the automatic state is switched back to the manual state, except that the disc will perform the slow positioning action (the disc is switched during the operation), and other actions are stopped in time. It can be reset manually.
2.4 electric power consumption of the disc machine is mainly reflected in the following parts
1) Power consumption of hydraulic system oil pump
2) Power consumption of the heater
3) Cooling fan.
For shoe-making enterprises, power consumption is the main part of its production cost. In the above-mentioned power consumption, the power consumption of the hydraulic oil pump accounts for about 80% of the electricity consumption of the entire disk machine, so the power consumption is reduced. The key to energy saving.
3 disk machine power saving principle
After understanding the working principle of the disc machine, it is not difficult to know that there is a very violent mutation process inside the disc machine action, and the impact on the machine is very large, which affects the life of the entire injection molding system. At present, there are a large number of old equipment in domestic shoe-making enterprises, with low automation and high energy consumption. Machines are generally designed for maximum production capacity, and in fact they do not use as much power during production. The rotation speed of the oil pump motor remains unchanged, so the output power is almost constant, and there is a phenomenon of large horse-drawn carriages in production. Therefore, a lot of energy is wasted.
Due to the characteristics of the main and auxiliary machines and rotary molds unique to the disc machine, there are not many effective mold positions used in production, such as: TY-322 model, 24 sets of molds, sometimes only 10 sets. There are even fewer molds used in the test machine and proofing, which determines that the main and auxiliary machines are often in a long standby state. The slave performs the action only when a valid mode is detected. When the disc rotates, the auxiliary machine does not perform any action. In normal times, the motor still works at the rated speed. At this time, the high-pressure overflow part not only does not do any useful work, but also generates heat, which causes the hydraulic oil to heat up. Can and is harmful.
We use the speed sensorless vector frequency conversion operation technology of the disc machine (refer to the electrical schematic diagram). The inverter detects the pressure and flow signal from the computer board of the disc machine in real time. The pressure or flow signal of the disc machine is 0~1A. After internal processing, the output of different frequencies, adjust the motor speed, that is: the output power and pressure and flow synchronous automatic tracking control, equivalent to the quantitative pump becomes an energy-saving variable pump, the original hydraulic system and the whole machine need to run Power matching eliminates the loss of high pressure relief energy from the original system. It can greatly reduce the vibration of mold clamping and mold opening, stabilize the production process, improve product quality, reduce mechanical failure, extend the service life of the machine, and save a lot of electric energy.
4 Disc machine energy-saving transformation case
In December 2004, we assisted the agent. In the Nanlong sole factory in Quanzhou, Fujian, a KV2000-Z0220-4T inverter was installed. By comparison, when the 22KW motor was at the power frequency, the power consumption per hour was 14 degrees, while the inverter operation was one hour. The power is 5 degrees, the hourly power is 9 degrees, and the power saving rate is as high as 64.3%. The local electricity bill is 0.80 yuan per kWh, and the equipment is calculated at 8640 hours per year. The annual electricity saving rate is 8640×9×0.8=62208 yuan. The table below lists some of the application of KV2000 speedless vector inverter technology, energy-saving retrofit case on the fully automatic disc type plastic injection molding machine, for users' reference.
Serial number company name installation time installed quantity average power saving rate
1 Dongguan Tangxia XX Shoes Material Factory 2004.05 86 sets 43%
2 Shenzhen Longgang XX sole factory 2004.08 8 sets 37%
3 Quanzhou Jinjiang Chenyu XX Sole Factory 2005.01 5 64
4 Shenzhen XX Plastic Factory 2004.09 16 sets 40%
5 Shenzhen Longgang Pingshan Biling XX Sole Factory 2003.08 16 sets 38%
6 Shenzhen Longgang Pingshan Biling XX Shoes Material Factory 2004.06 23 sets 42%
7 Dongguan XX Shoes Material Factory 2004.06 10 sets 33%
8 Shenzhen Longgang Longdong XX Shoes Material Factory 2003.07 9 sets 36%
9 Shenzhen Longgang Tongle Village XX Shoes Material Factory 2004.05 14 sets 52%
5 frequency conversion energy saving precautions
5.1 frequency conversion energy saving features
1) Simple operation, running synchronously with the disc machine, without any adjustment;
2) High reliability: keep the original control mode and oil path of the disc machine unchanged; adopt the mains/saving operation control mode to prevent the production from being affected when the fault occurs;
3) Soft start: reduce machine vibration, prolong the service life of equipment and mold; effectively reduce noise and improve working environment; system heat is obviously reduced, oil temperature is stable; extend the service life of seal components, reduce downtime maintenance rate, save a lot Maintenance costs, while increasing the installed capacity of the transformer;
4) High rate of return: Depending on the process, all investments will be recovered by electricity bills for about 6 to 12 months.
5.2 Automatic disc type plastic injection molding machine frequency conversion transformation considerations
5.2.1 Selection of Inverter and KV2000 Sensorless Vector Inverter Features The manufacturers involved in the inverter energy-saving transformation of the injection molding machine are all clear. After the inverter is used for energy saving, the production cycle will be prolonged. At the same time of saving electricity, production efficiency is reduced to varying degrees. This is because the general-purpose inverter adopts the traditional V/F control technology, and its startup time is long, the reaction speed is slow, and the torque is insufficient, which causes the power-saving manufacturer to reduce the mold and the pressure is insufficient. Some even increase the capacity of the inverter to compensate for the slow reaction, causing the oil pump motor to be overloaded for a long time, and the temperature rise is increased or burned. The above problem can be solved by using a speed sensorless vector inverter.
Komron Electric (Asia) Co., Ltd., the latest KV2000 series of high-performance speed sensorless vector inverters. The KV2000 series inverter is a new generation of multi-function standard inverters that can be widely used. It uses advanced sensorless-learn vector control technology to provide greater torque for low-speed operation of the motor. The speed of the motor changes during load. Good dynamic characteristics and superior overload capability to meet a wide range of applications.
KV2000 speed sensorless vector inverter has automatic tuning of motor parameters, the speed accuracy is up to 5‰, and the low frequency torque is up to 150%.
There are three control modes: speed sensorless vector control, output power (torque) control, and standard V/F control.
Modern communication function, much higher than the traditional general-purpose inverter 0-650Hz high output frequency, rich built-in PID function, unique cooling fan, nearly 200 kinds of control functions designed for industrial machinery, speed tracking function, unique automatic The variable carrier frequency is 2 to 16.9 KHz.
It is suitable for constant torque and constant speed control of general machinery such as various plastic machinery, chemical textiles, water pumps, fans, printing machines, conveyor belts, food packaging machinery, metal processing machinery. The KV2000 speed sensorless vector inverter is used to carry out energy-saving retrofits, which can achieve high power saving rate and ensure the original production efficiency and quality.
5.2.2 The influence of the frequency converter on the temperature of the disk machine and the solution
The frequency converter belongs to the power semiconductor device and has the problems of high frequency interference and low frequency harmonics. However, some application unit technologies are not professional enough to cause interference to the machine equipment control system, especially the temperature system. In severe cases, the system It will not work properly, and even the phenomenon of burning equipment will occur. The transformation unit shall install the output AC reactor of the same specification on the output side of the inverter according to the site environment and equipment conditions, in order to effectively filter out the higher harmonic components in the inverter output current and reduce the higher harmonics. Caused by electromagnetic interference. At the same time, the current waveform is improved, the motor running noise and temperature rise are reduced, and the running stability of the motor is improved.
When the temperature system is disturbed, we can also take the following steps: reduce the carrier frequency; connect the dedicated ground line; adjust the carrier frequency; add the magnetic ring, filter, AC output reactor on the output side; install the equivalent in the original heating system circuit A series of measures such as power 1:1 isolators are available.
5.2.3 Electrical protection
KV2000 speed sensorless vector inverter has all-round protection functions: low voltage, over voltage, over current protection, to prevent motor stall, overload, overheat protection, etc., to ensure that the inverter and motor are not damaged.
When designing the system, we must also consider the protection of the motor during the mains state. If you switch directly from the power-saving state to the mains state, it is equivalent to the direct start of the motor, and the starting current is 4 to 7 times the rated current. The impact on the equipment and the power grid is very large, and it is easy to cause premature damage to the contactor and even cause the motor to burn.
Therefore, it is recommended to stop the motor (Y-â–³ device of the original system), switch the power-saving device, and then start the motor.
6 Conclusion For most companies, the electricity bill is the last cost that is not controlled by the enterprise. It is generally believed that the electricity bill is difficult to control. The electricity bill is justified because the electricity consumed by the electricity equipment is determined by its electromechanical characteristics. Subjective control is powerless. Obviously, this concept is wrong. In the case of severe power shortages across the country, as our company, we should pay attention to energy conservation, pay attention to the adoption of advanced energy-saving mechanisms, and apply advanced technologies to minimize energy consumption, that is, to protect the environment and create Economic benefits. Practice has proved that by applying high-performance and high-quality KV2000 speed sensorless vector inverter technology and a series of technical management measures, enterprises can reduce operating costs by at least 20-60%.
KV2000 non-inductive vector inverter energy-saving retrofit technology in plastic machinery has been widely used and promoted in the plastics industry, and this technology has made outstanding contributions to China's energy-saving cause.
Vacuum casting offers a wide range of options for companies needing specific finishes,materials, or other features in their prototypes. We have the ability to simulate a full range of thermoplastics and elastomers, and we can also over-mold one
material over another to simulate, for example, rubber over ABS, or opaque plastic over transparent plastic. It is also possible to over-mold threaded inserts.
After casting, painting and printing is common, although polyurethane casted parts can be colored in the mold. EPT also specialize in producing high-gloss clear parts by using a CNC machined and polished acrylic master model. Polyurethane casted clear parts are very high quality.
We can create small and large urethane cast parts with production-like aesthetics and material properties for a range of applications, including medical and healthcare, military, automotive, electronics packaging, consumer products, and others.
China has continued its power supply shortage for nearly two years. By 2004, the situation was even more severe. In the first half of the year, there were 24 provinces and municipalities with power cuts. In the first half of this year, power demand was driven by 9.7% GDP growth, and continued to grow at a high speed. It was characterized by “maintenance of industrial power continues to grow rapidly, and electricity consumption in high-power consumption industries remains highâ€. However, the power supply capacity has increased finitely, and there has been a situation of insufficient supply. As a result, the contradiction between power supply and demand has become tense, and the areas of power shortage and areas with continued power shortages have further expanded.