Electric motors in packaging machinery

This paper discusses the working principle of the motor and the use of characteristics, introduces the motor in the packaging machinery in several application examples, pointing out that the motor in the packaging machinery has a broad application prospects.

First, the working principle of the motor

Motor is a given electrical pulse signal into an angular displacement or line displacement of the open-loop control element.

Given an electrical pulse signal, the motor rotor will turn the corresponding angle, this angle is called the motor step angle. Currently used motor step angle is mostly 1.8 degrees (commonly known as one step) or 0.9 degrees (commonly known as half-step)

The motor's step angle is 1.8 degrees (commonly known as one step) or 0.9 degrees (commonly known as half step). To step angle of 0.9 degrees for the progress of the motor, when we give the motor an electrical pulse signal, the motor turned 0.9 degrees; to two pulse signal, the motor turned 1.8 degrees. And so on, the motor can run continuously when given a continuous pulse signal. By

Because of this linear relationship between the electrical pulse signal and the motor angle, the motor has been widely used in speed control, position control and other aspects.

The use of the motor needs at least three aspects of cooperation, one is the electric pulse signal generator, it is repeated in accordance with the given settings for the motor to deliver electric pulse signals, most of these signals by programmable controllers or microcontrollers to complete; the second is the driver (signal amplifier), it is in addition to amplify the electric pulse signals, drive the motor to rotate in addition to improve the use of the motor performance, in fact, it plays an important role in the motor system. Motor system plays an important role, generally a motor can be based on different conditions with a variety of drivers; Third, the motor, it has a variety of control principles and models, now commonly used reactive, inductive subtype, hybrid

The speed control of the motor is realized by the input pulse frequency fast or slow. When the frequency of the incoming pulse decreases, the speed of the motor decreases; when the frequency increases, the speed increases. It is also possible to increase the speed or positional accuracy of the motor by changing the frequency.

The position control of the motor is controlled by the number of pulses given. Given a pulse, turn a step angle, when the position of the stop is determined, it also determines the number of pulses that need to be given to the motor. In packaging machine control, the number of given pulses is also related to the parameters of the mechanism, such as the diameter of the screw.

In packaging machinery, many cases need to control the running speed and running position of the actuator, which used to be done by mechanical or other means, the mechanism is complex, not easy to adjust. After changing the motor, not only can make the packaging machinery structure becomes simple, easy to adjust, reliability increases, and the roughness will be greatly improved.

Second, the application of the motor in the measurement of materials

1. Measurement of powdery materials

Screw metering is commonly used volumetric measurement, it is through the screw rotates the number of laps how much to achieve the measurement of how much, in order to achieve the measurement of the size of the adjustable and improve the accuracy of the measurement of the purpose, the requirements of the screw's rotational speed can be adjusted and the position of the positioning is accurate, the use of electric motors can simultaneously meet the requirements of these two aspects.

For example, the measurement of powder packaging machine using a motor to control the speed and number of revolutions of the screw, not only simplifies the mechanical structure, but also makes the control is very convenient. In the case of no load, the motor speed, stop position depends only on the frequency of the pulse signal and the number of pulses, without the influence of the load change, which has obvious accuracy advantages compared with the electromagnetic clutch control screw metering, more suitable for the specific gravity of materials with large changes in metering.

The motor and the screw are directly connected in a way that is simple in structure and convenient in maintenance. It is worth pointing out that, such as the motor's overload capacity of the generation, when a slight overload, there will be considerable noise. Therefore, in the measurement of working conditions to determine, we must choose a larger overload coefficient, in order to ensure the balance of the motor work.

2. Measurement of viscous materials

Motor-controlled gear pumps can also realize accurate measurement. Gear pumps in the transport of viscous body has been widely used, such as syrup, bean paste, white wine, oil, tomato sauce and other transport. Currently in the measurement of these materials mostly use piston pumps, there are difficulties in adjustment, complex structure, inconvenient maintenance, power consumption, measurement is not allowed and other shortcomings.

Gear pump metering is by a pair of gear meshing rotation measurement, the material through the teeth and teeth of the space is forced from the inlet to the outlet. Power from the motor, motor rotation position and speed controlled by a programmable controller, metering accuracy is higher than the piston pump metering accuracy.

The motor is suitable for running at low speed, when the speed is increased, the noise of the motor will increase significantly, and other economic indicators will be significantly reduced. For gear pumps with relatively high speed, it is better to choose a speed-up structure. We began to use in the viscous body packaging machine is the motor directly connected to the structure of the gear pump, the results of the sound noise is difficult to avoid, the reliability of the decline. Later, the use of straight gears to speed up the approach to reduce the speed of the motor, the noise has been controlled, reliability has also been improved, metering accuracy has been ensured.

Third, the motor in the supply and delivery of packaging film applications

In the bag making, filling, sealing as one of the packaging machine, the requirements of packaging plastic film positioning fixed-length supply, whether intermittent supply or continuous supply, can be reliably accomplished with the motor.

1. For batch-type packaging machine

The reliability of intermittent packaging machine can be improved by using electric motor to supply film. In the past, the film supply and feeding mostly used the crank linkage mechanism to pull the belt intermittently, which has a complicated structure and is difficult to adjust, especially when it is necessary to change the products, not only is it difficult to adjust, but also there is a lot of waste of film. The use of motor and belt roller directly connected to the belt, not only the structure has been simplified, and the adjustment is extremely convenient, as long as through the control panel buttons can be realized, which not only saves the adjustment time, but also saves packaging materials.

In the intermittent packaging machine, the supply and delivery control of packaging materials can be in two modes: bag length control mode and color code control mode. The bag length control mode is suitable for packaging film without color code, which is realized by the method of pre-setting the motor speed, and the setting of the turn-air ratio can be realized by a dip switch. Color code mode is equipped with photoelectric switch, photoelectric switch detects the position of the color code, when the color code is detected, it sends out a control switch signal, the motor stops rotating when it presses the signal, and then rotates to supply the film after a certain delay time, week after week, to ensure that the film is supplied at a fixed length in accordance with the position of the color code.

2. For continuous packaging machine

In the continuous packaging machine, the motor rotates continuously, the packaging film is transported evenly and continuously, and when the bag length is changed, it can be realized only through the dial switch.

IV. Application of motor in cross sealing

In the continuous packaging machine, the horizontal seal is a very important actuator, but also one of the more complex mechanisms in the packaging machine. Especially for colored grade packaging film, its sealing and cutting position requirements are extremely strict, in order to improve the accuracy of the cut off, people have developed an eccentric sprocket mechanism, crank guide rod mechanism, etc., but these institutions are the existence of a very troublesome adjustment, the shortcomings of low reliability. The main reason for these shortcomings is that the process requires a fixed-speed cross sealing wheel and positioning cut-off.

Motor directly drive the sealing wheel can achieve speed synchronization. Continuous packaging machine film supply wheel is a continuous film supply, cross sealing requires cross sealing of the line speed and film supply and delivery speed synchronization, to avoid tearing film and film buildup, due to the diameter of the cross seal wheel is constant, when changing the length of the bag, it is necessary to change the speed of the cross seal wheel by changing the speed to change, but cross sealing requires a certain amount of time, that is to say, the cross seal wheel and the film from the contact to the departure of the need for a constant amount of time, otherwise Otherwise, the sealing is not tight. The total time of each revolution of the sealing wheel and the time needed for sealing are constant. To meet the requirement of speed synchronization, the rotational speed of the motor in a week can be divided into two parts, one part of which firstly meets the requirement of speed synchronization, while the other part of which is unloaded meets the requirement of the total time of a week.

In order to achieve good sealing quality, can also be achieved through the motor on the cross sealing wheel non-equilibrium speed control mode, that is, in the cross sealing of each point to achieve speed synchronization, limited to space, will not be stated here.

The characteristics of the motor are mainly attributed to three aspects, one is good overload. Its speed is not affected by the size of the load, unlike ordinary motors, when the load is increased, there will be a drop in speed, so the motor is used in the speed and position have strict requirements of the occasion; Second, the control is convenient. Motor is a "step" for the unit of rotation, digital features are more obvious, so that the computer control has brought great convenience, in turn, the emergence of computers has also opened up a broader use of the motor market; Third, the machine structure is simple. The traditional mechanical speed and position control structure is more complex, difficult to adjust, the use of motors, making the structure of the machine becomes simple and compact.

Motor in the packaging machinery on the use has just begun, it turns out that many of the traditional mechanical control can be replaced by the motor, in addition to some of the uses described above, it is also in the printing, filling, bag and other aspects of the application, I believe that in a relatively short period of time, China's packaging machinery industry will be able to motor technology on the platform to leap to a new level.