Application of the OMRON encoder in the blast furnace feeding system

1 Introduction

Shaoguan smelting factory closed OMRON blast OMRON furnace feeding system mainly completes the preparation bin feeding, weighing, transport, until the material is added into a encoder blast encoder furnace encoder in the process of automation control, mainly including discharging encoder system, encoder car encoder transport system, crane system, blast furnace bell system, blast furnace probe rod system, a cold coke charging system. Transport vehicles running hoist tower and the discharge zone between, the warehouse for preparation of material is transported to hoist tower, transport vehicle in the discharge zone of parking point nine, ascending the tower has two parking spots. The transport vehicle is running fast, forward and backward, and the reverse is fast, and the reverse is slow, and the running of the parking spot is fast. In actual use, due to the trip switch, deceleration switch field machinery installation difficulty and easy to be damaged and being high temperature, moisture problems and other issues, and encoder has convenient installation, accurate positioning, no mechanical loss using long life, so the transformation will transport vehicle system deceleration switch remove, instead of encoder and a stroke switch dual control (with parallel priority). OMRON e6b2-cwz1x encoder for linear drive output type, three-phase six wire system (not including the power cord), the maximum extension of the lead 100m, fully meet the requirements of production. PLC of the system uses ac800m abb, the signal of the receiver module is dp820.

2 Hardware principle analysis

Rotary encoder is a device that converts angular displacement or linear displacement into electrical signal. The encoder converts the displacement into a periodic electrical signal, and then converts the electrical signal into a counting pulse, which indicates the displacement of a number of pulses. The encoder generally has 3 output phases: a phase, B phase, Z phase. When the encoder rotates, the A and B phases differ by 90 degrees. By comparing the positive and reverse of the a phase, the B phase is in the former. The output of a Z phase pulse is represented as a reference bit. Signal output (current or voltage) sine wave, square wave (TTL, HTL), collector open (PNP and NPN), push and pull type a variety of forms, including TTL for long-term difference driven (symmetric a, alpha; B, beta, Z, z), HTL, also known as push pull type and push-pull output, the encoder signal receiving device interface should correspond to the encoder.

E6b2-cwz1x is Omron e6b2 series of line drive output type incremental coding device, od 40, power voltage dc5v combined production actual, selection of resolution for 1000 pulse/rotating, output way (see Figure 1) for a,, and a-,b, and b-,z, and z-connection, due to with symmetric negative signal of connection, current for cable contribution of electric magnetic field for 0, attenuation minimum, anti-interference best, can transmission more far of distance. E6b2-cwz1x wire may be extended to 100m.

Dp820 is a 2-channel pulse count module, each channel has a digital input and digital output, per channel total 5 count mode, according to the actual production, this time on the selection of a count, count under b. Dp820 accept the encoding the signal, according to the direction of rotation to count down the judgment. Transfer vehicle during operation, each stopping point, count value of the deceleration points are fixed, by comparison to determine the direction of transfer vehicle, speed, state dp820 the module parameter settings, as shown in figure 2 below.

3 Application software design and debug

Transport workflow are as follows: System startup, the program automatically selects the tower parking memory →according to the tab stop selected →operation→ loading discharging  → back to parking spots under the selected tower→ press → change tank material order to continue feeding.

Tabulation parking choice point, will the stopping point for the pulse value and the stopping point of deceleration point pulse value is assigned to two variables, the direction and speed of transport vehicle, state transfer vehicle current pointer variables according to value and a deceleration point, stopping point value comparison of the obtained, if the current value less than deceleration values quickly, if the current value between deceleration values and parking between point values for slow, if equal to stopping point for the value of a stop start feeding. The parking point by manual car to the fixed position, and then take the value of the counter. Transport vehicles on the South Group, the North group of materials. When the transport vehicle stops at the parking point of 10, it is the North group. When the parking area is 11, the feeding of the south. In this way, the distance of the car is not the same, so the number of pulses in the parking area is also different. In the North group, the value of the program is shown in figure 3:r400601, r400611, and the pulse count value of 9 parking spots in the discharge area.

The comparison part of the program is shown in Figure 4: signal b000702 indicates that the transport vehicle is in the running state, and the r300003r is the number of pulses transmitted by the encoder, and the r402602, r402601, respectively, are initialized by the program. The output above is b000703, with a signal that the transporter is slow; the output is b000704, and there is a signal indicating that the transporter is stopped

This part of the software design is relatively simple, the key is to accurately and quickly get the value of the encoder, the encoder is a relatively high sensitivity of components, interference may make a large number of errors. In the debugging process of this system, once the frequency converter, the counting will start to appear disorder, even when the encoder is at rest, the counting module is still kept up counting, which fully shows that the converter has a great influence on the encoder and its receiving module.

When the inverter is running, it can produce the power of the large harmonic, and the other equipments are very strong, and the interference way is mainly divided into circuit coupling, electromagnetic radiation, induction coupling and so on. To solve a lot of inverter interference methods, mainly to shield the disturbance source, the inverter output line transfer pipe, the inverter cabinet and PLC cabinet to maintain a certain distance, the inverter simulation signal cables and the motor power line put on fire ring, the inverter carrier frequency in the lowest value. Because of the interference of the system is relatively large, almost make the system can not work, so the use of shielding interference sources, that is, with a metal cover to cover and the inverter cabinet. After the system is normal.

4 concluding remarks

Replace speed switch, limit switch with encoder, which facilitates the design of system and greatly reduce maintenance OMRON staffs OMRON workload, low failure and high degree of accuracy, and engineers should learn from it