Views: 9 Author: Site Editor Publish Time: 2018-05-25 Origin: Site
In order to realizing the automatic function of the steel row nail automatic row-discharging device and improve the production efficiency, the design adopts pneumatic technology, automatic detection technology and PLC (programmable controller) control technology, and pushes the nail solenoid valve, the suction nail solenoid valve and the electromagnetic Iron is controlled. At present, PLC has been widely used in the field of intelligent control of nail industry. Considering that the requirements of this control system are not too complicated, and precise timing is required, for the convenience of debugging, PLC is selected as the control host. The input signal is 2 and the output signal is 3. The input signal is provided by the push nail proximity switch and the nail head detection proximity switch; the output point is connected with the electromagnetic relay or the electromagnet, the electromagnetic relay controls the electromagnetic valve, and the electromagnetic valve controls the suction/exhaustion action of the push nail and the suction nail cylinder.
The specific process control is as follows:
1.Push-pin control
When the push nail proximity switch has a signal, the push nail relay pulls in, the push nail control solenoid valve changes from the right position to the left position, and the push cylinder piston rod extends to complete the push nail action; when the timer in the PLC is finished The push pin relay is disconnected, the piston rod is retracted, and the cycle is automatically pushed. Since the push nail approaching switch generates a signal and disappears immediately, if the cylinder's operating time is not properly extended, this phenomenon occurs. The cylinder piston rod retracts as soon as it protrudes. This will not achieve the intended purpose, so it must be delayed. After the test, the extension time of the push rod cylinder rod extension is 0.3s.
2. Sucker control
When the nail head detects that the proximity switch has a signal, the suction nail relay pulls in, the suction nail control solenoid valve changes from the right position to the left position, the suction cylinder cylinder rod extends, and the electromagnet is fixed at the end of the suction rod cylinder rod. Electricity produces magnetism. When the piston rod reaches the maximum stroke, the electromagnet sucks the electromagnet that does not meet the requirements, and then the nail relay is disconnected and the piston rod is retracted. At this time, the electromagnet still needs to be energized to suck the steel nail and pull him out of the skateboard. When the PLC timer ends, the electromagnet is powered off and the steel nail is thrown away. In this cycle, the steel nails that do not meet the requirements will be removed. During the test, the piston rod of the suction nail cylinder needs a delay of 0.3 s during the extension process, and the electromagnet is delayed by 0.5 s after being energized.
3. Selection of control components
In order to achieve the above control process, the appropriate control elements must be selected. Selection of PLC (programmable controller) Programmable controllers are a new generation of industrial automation control devices that have been rapidly developed and widely used in recent years. Early programmable controllers could only implement logic in terms of functions, so they are called programmable controllers. In the standard promulgated by the International Electrotechnical Commission in 1985, the programmable controller was defined as: The programmable controller is an electronic system designed for digital computing operations for industrial applications. It is a programmable memory that stores instructions for operations such as logic operations, sequence control, timing, counting, and arithmetic operations, and controls various production machines or digital and analog inputs and outputs. process.
4. Proximity switch selection
During the working process of the steel row nail automatic rowing device, the object to be tested is the steel nail, and the steel nail is relatively small (diameter 2.2mm, length 50mm), so the general sensor can not be detected. Here, an inductive proximity switch is selected.
The inductive proximity switch belongs to a position sensor with a switching output. It consists of an LC high-frequency oscillator and an amplification processing circuit. When a metal object approaches the oscillation induction head capable of generating an electromagnetic field, an eddy current is generated inside the object. This eddy current reacts to the proximity switch, causing the proximity switch to oscillate and the internal circuit parameters are changed, thereby identifying the presence or absence of a metal object, thereby controlling the on or off of the switch. The object that this proximity switch can detect must be a metal object. According to the mutual position of the skateboard, the cylinder, the push plate and the collecting bucket, the pusher proximity switch parameters are: model J18-D8PK; working voltage DC24V; current 200mA; detecting surface diameter is 18mm, detecting maximum distance 8mm. The nail head detection proximity switch parameters are: model LJ8A3-2-Z/BX; working voltage DC24V; current 300mA; detection surface diameter 6mm, detection maximum distance 3mm.
5. Selection of electromagnetic relay
Since the selected electromagnetic reversing valve is AC220V, and the output voltage of the PLC is DC24V, the PLC cannot directly control the electromagnetic reversing valve. It is necessary to first use the PLC to control the electromagnetic relay, and the electromagnetic relay to control the electromagnetic reversing valve. Therefore, the operating voltage of the selected electromagnetic relay must be DC24V. In order to ensure performance, the relays of relays, sensors and some switch products are selected: model MY2NJ, working voltage DC24V, current less than 5A.
6. Electromagnet design
An electromagnet is an electrical device that generates a suction force to a ferromagnetic substance after being energized and converts electromagnetic energy into mechanical energy. It is widely used in the field of engineering technology. There are many types of electromagnets, but their basic components and working principle are the same. The structure of the electromagnet is not very complicated, and generally consists of three main parts: the coil, the core and the armature. However, it is also possible to have no armature, and to use the work object as a movable absorbing body, which is equivalent to the role of the armature. The electromagnets can be divided into a holding type and a suction type according to the action mode. Holding electromagnets are used to hold any mechanical parts, loads of magnetic materials, objects being processed and transported, and the like. This electromagnet has no armature of the movable portion, and the magnetic flux is closed by the held workpiece (of course, the workpiece is a ferromagnetic substance). The attracting electromagnet itself has a moving armature. When the coil is energized, the armature is attracted to a certain distance and this motion is transmitted to other loads that require mechanical motion.
According to the type of power supply of the excitation coil, it is divided into a DC electromagnet and an AC electromagnet. The coil of the DC electromagnet is connected to direct current, and the established magnetomotive force does not become constant magnetic flux with time, and there is no overcurrent and hysteresis loss in the core. The core material can be made of monolithic steel or engineering pure iron. The processing is convenient, and the core of the coil part is often made cylindrical. The excitation coil of the AC electromagnet is connected to an alternating current, and the established magnetic flux varies with a certain frequency of the power source. Therefore, the ferromagnetic object through which the magnetic flux passes has overcurrent and hysteresis loss. At this time, the iron core can no longer be fabricated from a single piece of steel, and is usually formed by stacking a plurality of very thin electrical steel sheets. For ease of manufacture, the core is square and the coils are often square.
In the process of sucking nails of the steel row nail automatic row discharging device, it is necessary to use an electromagnet to suck out the steel nails that do not meet the requirements from the steel nail queue, and then the electromagnet is powered off, and the steel nails are thrown away.
