application. Reconstruction of the control part of the AC W200H boring and milling machine Liu Guoguang (Huangshi College, 435003) The original W200H boring and milling machine has good mechanical transmission performance, the armature carbon brush of the motor is seriously worn, and the spindle motor electric control system is separated by discrete components and small scale. The circuit is made up, the volume is large, the work is unstable, and the maintenance is complicated. To this end, it was decided to modify the control system of the equipment.
1 The overall transformation scheme feed motor power is 11kW, armature rated voltage 440V, rated current 28.5A, magnetic field rated voltage 190V, magnetic field rated current 1.6A, rotating speed is 3600r/min, Z-axis feed drag motor power is 6kW, armature rated voltage 440V, rated current 15A, magnetic field rated voltage 190V, magnetic field rated current 1. Speed ​​3000r/min Electrical control uses armature voltage regulation, DC irreversible system, acceleration and start when starting and braking The process of slowing down.
1.2 spindle drag electrical system requires the use of thyristor speed control, armature reversible logic loopless double closed loop control system, rated DC output voltage 440V, current > 410A, rated excitation voltage 220V, current 4.7A, according to machine tool transmission speed Range requires medium-sized horizontal boring machine D (main drive) = 25~60, (speed range D=ninax/nmin) and finishing machine S<0. Technical requirements for feed-and-drag electrical system, requiring thyristor adjustment Speed, armature reversible, rated DC output voltage 440V, current >30A, rated excitation voltage 190V, according to the machine drive speed regulation range requirements D (feed drive) = 30 ~ 150, (the speed range D is better, otherwise Creeping at low speeds).
1.3 The relay control part is safe and reliable for the logic of the relay. The line is simple and easy to maintain. The design of the whole electrical system must comply with the relevant national electrical standards. To this end, the Mitsubishi programmable controller FX2N*128MR was used to replace the huge relay logic circuit of the original machine tool.
2 spindle drag electrical system transformation spindle drive electrical system is the most important part of the trampoline electrical system, it is directly related to the machining performance of the machine tool, in the spindle drag electrical design, should use the armature reversible logic loopless double Closed loop speed control. The speed regulation range of the motor is divided into two areas, which are constant torque mode speed regulation under the rated magnetic field, and the weak magnetic speed increase mode is constant power speed regulation.
In a reversible circuit composed of two sets of thyristors and anti-parallel, a circulating current may be generated under certain conditions. The so-called circulating current is the current flowing between the two sets of thyristors without passing through the load, which is divided into a DC circulating current and a pulsating circulating current. Circulation is unfavorable to the speed control system. Because of the circulation, the rectifier transformer and the thyristor capacity will increase. Originally, a balanced reactor with a limited circulation was added to reduce the circulation. Logical loopless flow is a kind of logic device to realize loopless flow. In the loopless speed control system, the reactor that restricts the circulating current is eliminated, thus saving cost.
The double closed-loop speed control system has the advantages of fast dynamic response and strong anti-interference ability. Its static characteristics are typical excavator characteristics and are a basic form of automatic speed control system.
The spindle dragging electrical system adopts the wide-speed DC spindle system ZSK-435A with high performance and domestic price. The system is DC reversible, the armature and magnetic field voltage are adjustable, the output current is 435A, the speed regulation range is 1:100, and the static difference is ± 5%. The drag system of the Y, Z and Z axis feeds adopts the DC wide speed servo device SZKK - DC reversible, the output current is 50A, the speed range is 1:40ft, the static difference is ±4%. These two DC systems are The use of more integrated circuits makes the volume smaller, the power consumption is small, the anti-interference ability is strong, the maintenance is convenient, and the cost performance is high. From the main technical indicators, it can fully meet the transmission speed requirements of the boring and milling machine.
When debugging the machine tool spindle, the parameters of the speed regulator and the current regulator should be adjusted according to the actual parameters of the machine tool to achieve the optimal start-up and braking transition process. At the same time, the limit current value and the field weakening point should be given. The values ​​are set to achieve the best drag effect.
3 Feeding and dragging electrical system transformation It is directly related to the machining performance of the machine tool. In the electric design of feed and drag, in addition to the armature reversible logic loopless double closed loop speed control, the W200H boring and milling machine X needs to be considered. The load of the shaft drag is nearly one hundred tons, the load of the Y-axis drag is nearly sixty tons, such a large load, and the drag motor is only 11kW. Due to the inertia, it must be gradually accelerated at the start, and gradually slow down when stopping. . Otherwise, when the motor is started, the motor will be blocked due to excessive torque required and cannot be started. When parking, the transition time is too long, reducing production efficiency. For this we use a given integrator circuit.
The function of this circuit is to output a ramp voltage linearly related to time according to the output command of the logic circuit and the voltage reference value on the Rp potentiometer as the given voltage of the feed speed.
The working principle is that the circuit of the given integrator consists of three operational amplifiers Ai, A2 and A3 and a RC network. Usl., Ui, U2, and Usc are the output of the input step signal, operational amplifiers Ai, A2, and A3, respectively, where the operational amplifier Ai is approximately open-loop, and its amplification factor is large, as long as US1 is greater than its limit value. The 1/100 output Ui will reach the limit value; the operational amplifier A2 constitutes the inverter, so that the whole integrator can form a negative feedback closed loop; the operational amplifier A3 and the capacitor form an integral link, which turns the US1. A signal for a certain slope. Their voltage waveforms are as follows.
A negative sign indicates that the polarity of Usc is opposite to that of U2. It can be seen from the formula that in the tlt2 phase, Us<: increases linearly with time; in the t2*t3 phase, U2=0, the integrator stops working; in the t3t4 phase, the Usc decreases linearly with time.
When debugging the machine feed and drag system, the X, Y, and Z axis drag systems are adjusted according to the actual parameters of the machine tool. In addition to adjusting the parameters of the speed regulator and the current regulator, the integration time is mainly adjusted. Limit current (generally set the limit current at start-up to 2.5 times the rated current) for optimal start-up, braking transitions and drag effects.
4W200H boring and milling machine PLC design PLC selection mainly considers the number of I/O ports required by the machine tool (in order to save the I/O port, if the machine part has entered the PLC, it will occupy more than a dozen I/O ports, and simplify The function of the circuit is not obvious, then it is not good to enter the PLC). Generally, the number of I/O ports of the selected PLC is more than the number of I/O ports required by the machine, because some I/O ports may be considered during machine design, and I/O ports may be added during machine tool debugging; After use, sometimes it is necessary to modify and add some functions, and I need to increase the I/O port. After many years of use, some I/O ports will be damaged. If there is a wealthy I/O port, you can change the port and program without changing the PLC. . According to the actual needs of the machine tool I / O port more than 50, so I / O port each has 64 Mitsubishi can be compiled 5 Conclusion This project has been successfully completed and has been put into use, the practice has proved that all electrical systems are stable and reliable , fully meet the processing performance of W200H boring and milling machine. Therefore, in the transformation of the machine tool should pay attention to: a. fully maintain and play the advantages of the original equipment; b. carefully analyze the control requirements of each part; C. try to use advanced and mature technology and well-known manufacturers of yuan, devices.
Only in this way can it be ensured that the technical transformation funds are used reasonably, with short cycle and good reliability.
A sleeping bag (sleeping bag) is a bag used for sleeping. The vast majority of sleeping bags on the market are labelled with a comfort temperature and an extreme temperature. The comfort temperature is the range of temperatures at which the user sleeps throughout the night, with a maximum and a minimum. The maximum comfort temperature is the kind of heat you feel in a sleeping bag but not when you are sweating profusely, and is generally defined as a sleeping bag with the zip open, arms outside and the head of the bag not tightened, etc.
Development history
Early humans were using animal fur to make warm clothing and sleeping mats, which are still used today, including by the Eskimos living near the Arctic. early 19th century explorers and mountaineers began to test different sleeping bag systems, early sleeping bags were filled with camel hair, which has excellent insulation properties, and then a hollow rubber air mattress was invented and used in the 18th century In 1861 Francis Fox Tuckett tested the first Alpine sleeping bag prototype, and in the mid-1860s the envelope sleeping blanket design began to be perfected, and near the ground are hollow rubber coating as a ground thermal insulation layer.
The role of the sleeping bag is simply to keep heat loss to a minimum, while the body inside the sleeping bag is constantly generating heat to keep warm, the amount of heat generated varies from individual to individual and from situation to situation, all sleeping bag temperature calibration systems are based on a standard human body, but such a standard human body basically does not exist. A sleeping body has approximately 75-100 watts of thermal power, which translates into approximately 47-55 watts per square metre based on the surface area of the body. The amount of energy produced by metabolism is very complex and relates to age, gender and even the amount of fat under the body, but by and large a fit young male always produces far more body heat than an older man or woman. The perception of cold is related to age and experience, with novices generally feeling colder than experienced climbers. People who work outdoors a lot feel warmer in cold conditions than those who work in an office a lot.
Use
Whether it is a down or synthetic cotton sleeping bag, try not to compress it up when it is not in use for a long period of time to keep it as fluffy as possible, and it is good to get a proper tan. The purpose of this is to maintain the nature of down and cotton and extend the life of the bag, especially for down sleeping bags, try to keep them in a special down sleeping bag storage bag (loose breathable cotton bag). As a personal hygiene product, try to avoid borrowing each other's sleeping bags.
When using a sleeping bag there are several ways to improve warmth.
Equip a good quality moisture-proof pad, which is very important, as anyone who camps a lot has experienced, if the cold air goes straight from the ground to the back, that kind of cold is unbearable; drink a hot drink before bed if possible, milk and fruit jelly are fine to warm up the body.
Eat a comfortable meal before bedtime, especially with carbohydrates (starches, sugars).
wearing a long set of thermal underwear and clean socks will be very effective.
wearing more clothes when the sleeping bag is not warm enough, or covering the sleeping bag with clothes and other items.
sharing a tent with a larger number of people.
lighting a gas lamp or cooker in the tent if it is safe to do so.
Build a fire. There are so many ways to do this, so try them out when it matters.
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