First, filling the overall structure

This automatic filling machine is the use of mechatronics technology measurement filling system. With programmable logic controller (PLC) and weighing instrumentation to form a measurement and control weighing and filling machine to complete the slices of weighing, measuring, filling the production process. The weighing and filling machine takes PLC and weighing instrument as the core, with weighing module, pneumatic actuator, electric actuator, automatic control parts and mechanical devices to realize the dynamic on-line weighing, measuring and filling of slices.

The control parts of the metering and filling machine are composed of two parts.

1、Disk filling part: it is composed of main control cabinet, vice control cabinet and two field operation boxes. The main control cabinet mainly contains PLC and weighing instrument F701, as well as code plate setter and bag counter. The vice-control cabinet is mainly for AC contactors and thermal relays, respectively, to control the M1 fan motor, M2 lifting mechanism motor, M4 transmission mechanism motor, of which the lifting mechanism uses two contactors due to the ascending and descending. The on-site operation box AR1 is used for material opening lifting control and AR2 is used for transfer control. The two control cabinets have corresponding signal indicators, buttons and knobs on the front panel.

2, the field part: ① three motors M1, M2, M3; ② four two-position five-way solenoid valve with a cylinder to control the feeding door 1 (solenoid valve YV1), feeding door 2 (solenoid valve YV2,) the discharge door (solenoid valve YV4) and the bag mouth clamp release (solenoid valve YV5); ③ six limit switches, SQ1 for the feeding door off position, SQ3 for the discharge door off position, SQ4, SQ5, SQ4, SQ5, SQ6 and SQ7 correspond to the upper, lower, upper and lower limits of the material opening of the bagging and lifting mechanism respectively; ④ 3 weighing modules BP1, BP2 and BP3; ⑤ 1 photoelectric switch SQ11 is used for detecting the end of the material packet to the conveyor chain plate.

The main mechanical devices of the filling system are weighing hopper, plate conveyor, bagging mechanism, control door and discharge door. As the slices are granular uniform particles, compared with powdery materials with good fluidity and non-adhesion, so the material can be dropped by its own weight, and the hopper does not need to do special operations. One of the control door is a double gate, control door 1 and 2 full open for fast feeding, control door 2 closed 1 open for slow feeding.

Second, filling process

This liquid filling machine has automatic and manual operation, but the manual mode is also realized by the PLC. Manual mode is mainly used for debugging, maintenance and troubleshooting, so take automatic operation as an example as follows:

①, weighing process: F701 automatically deduct the tare weight, open the control door 1 and 2, from the silo to the weighing hopper fast feeding (fast feeding speed of about 23Kg / s), when it reaches the preset value, close the control door 2, fast feeding is changed to slow feeding (speed of about 2Kg / s), when the material volume reaches the value of the fallout, close the control door 1, the end of the feeding. After stabilization, PLC sends data holding signal to F701, F701 automatically compares with the set under, over and upper limit values, if the right amount, the "weighing" light will be on, if over or under the amount, the "over" light will be on and alarm will be given.

②, lifting mechanism action and discharge process: the empty bag clamped on the discharge port plus a good, press the AR1 "mouth to rise" button to be "weighed" light is on the mouth of the material automatically rises to the upper position, the fan starts to inflate for 15 seconds, after the end of the inflatable open the discharge door to start discharging when the F701 sends a signal close to zero, then the "weigh good" light is on. When F701 sends out a signal close to zero 5 seconds after closing the discharge door, and then automatically release the bag mouth clamps, while the bag count plus 1, PLC to F701 to send a skin repeat position command signal, the bag filled with material out of the material mouth placed on the conveyor.

③, the transmission process: press the AR2 "transmission start" button, M4 start automatic transmission of a bag to stop, by manual zipper bag mouth, the mouth of the material is automatically lowered to the next position. In the future, each weighing a good bag, press the transmission start button bag that is the order of the forward transmission of a workstation. So the cycle is repeated. Forklift in a timely manner to the conveyor on the bag forklift away.

When the amount of under-allowed by pressing the "slow drop" button for replenishment and automatically reach the right amount; overweight weighing and filling machine in addition to the alarm without corrective measures, must press the "mandatory" button to open the discharge door to release the material.

Third, PLC and F701 with the use of

The core control part of this quantitative filling machine is PLC+F701.

① PLC selected is cost-effective and scalable Omron's C200HE, a total of 7 I / 0 card. There are four DI cards, model ID212 DC input unit, a total of 32 inputs, including F701 control output signals and buttons, knobs, limit switch inputs; three DO cards, model OC222 relay output unit and OD411 transistor output unit, a total of 20 outputs, including solenoid valves, motor control signals, signal lamps and control signals to F701. and control signals sent to F701.

② The weighing instrument is Model F701 of Nissan UNIPULSE with high precision and good reliability. the setting of F701 is carried out through the combination of buttons on its panel.

The weighing module interface is connected to the weighing module on the site using a four-wire system, and this automatic liquid filling machine is to use the three sensors on the site in parallel. The setpoint interface is connected to a 5-digit dial setter, corresponding to thousands and tens of digits, which is used to set the final value. The F701 can set the final value through the combination of keys on the panel or through the connection of an external setter, which can be switched through the combination of keys, and the latter is the case of this automatic liquid filling machine, where the final value can be corrected in units of 100 grams.

The control signal input/output interface is used to connect the external signal input and control signal output, 3 signals are sent from PLC, which are tare weight, tare repeat position and data hold; tare weight before each weighing, at this time, the net weight is set to zero immediately, and the data is held after the final value of weighing, and then the tare repeat position is used at the end of discharging, i.e., the tare operation is canceled, and at this time, the gross weight and the net weight is the same value, which ensures that the net weight of the slices weighed each time is the same, and the net weight of the slices is the same. This ensures the net weight of the slices weighed each time. There are 5 signals sent to PLC, which are close to zero, preset value, drop value, insufficient, excessive and upper limit. The actual parameters are set as follows: the upper limit value is 1200Kg, the lower limit value is 0Kg, the near zero value is 10Kg, the preset value 1 and 2 are 30Kg (F701 supports three-speed feeding, and this weighing and filling machine only uses two speeds, so the preset value 2 signal is not used), the fallout value is 1.7Kg, the excess and insufficiency are 0.8Kg, and the end value is 1000Kg. In the PLC program, this signal is sometimes used as the end value signal. Signal is also sometimes used as a final value signal, because the weight to fall short of the value of the control door to close the end of the end of the feed, the time only exists in the valve closure with the time interval, the size of this value is to close the control door has not fallen into the hopper weight of the slices. Practical use that is (code plate setter set to 1000.0 when): weight in 970Kg (1000.0-30) before the fast feeding, in 970Kg to slow feeding, in 998.3Kg (1000.0-1.7) when the control door is closed, this 1.7Kg is the amount of fallout; in the process of discharging the material to the weight to the 10Kg, and then a delay of 5 seconds to close the discharge door to ensure that the material has been discharged. The material has been discharged.

As the weight does not change after power down and power up again, and after a fault occurs during operation and stops operation until the fault is removed and operation is resumed, the programming of PLC is relatively simple, and there is no need to consider the data retention function, i.e., there is no need to use special memories and corresponding commands within the PLC.

Fourth, with the external handover signal

The high and low alarm signals of the silo are introduced into this weighing and filling machine, which are displayed on the panel of the control cabinet with signal lamps to remind the operator of the material condition of the silo. As the weighing and filling machine is far away from the central control room, in order to facilitate the central control personnel to understand the operation of this device, so the filling of weighing and filling machine running, stopping, fault signals introduced into the central control room of the DCS weighing and automatic filling machine, in addition to the measurement of the automatic filling machine bag counter plus 1 at the same time to send DCS a pulse signal is also used for counting to facilitate the work of statistics. And also the weight of each package into a 4-20mA signal into the DCS weighing and filling machine display.

V. Conclusion

Filling is a necessary condition for the product into circulation, and the main means of realizing the filling is to use the measurement of automatic filling equipment. Weighing the accuracy of the filling will directly affect the credibility of the enterprise and economic benefits. This filling weighing filling machine maximum filling capacity of 32 bags / H, the operator only 2 to 3 people, easy to operate. Control weighing and filling machine components almost all imported products, high reliability, low failure rate, easy maintenance. Weighing accuracy is designed for 1000Kg ± 0.8Kg. The weighing and filling machine since the use of the measurement of the Department of the two tests, the entire measurement of the weighing and filling machine dynamic metering accuracy of better than 0.2 ‰. Since the device drive products since the export of no customers reflect the weight of the products have weight problems, very good maintenance of the company's reputation.