Though there are too many models of labeling machine in the world, their working principles are similar. All of them consists of label peeling, transfering and rolling machnism devices. Only the control model may be different. Generally, the self-adhesive labeling machine is composed of a labeling mechanism, a rolling mechanism, a hot stamping mechanism, a conveying mechanism, a transmission mechanism, a frame and a control system. Among them, the rolling mechanism is also divided into a rolling rolling method suitable for flat bottles and a rolling seat rolling method suitable for round bottles. At the same time, the self-adhesive labeling machine is divided into vertical and horizontal types according to the state of the bottle; according to the speed of label delivery, it is divided into low speed, medium speed and high speed; There are few bottles in the pharmaceutical industry); according to the veneer requirements, it can be divided into single-sided stickers and double-sided stickers; according to label characteristics, it can be divided into general labels and transparent labels.

1. selection from the main function and control

In the past, the labeling position detected by the self-adhesive labeling machine was based on the front edge of the bottle body as the photosensitive point. Because the bottles of different diameters need to be moved by the corresponding electric eye or the labeling time should be changed, if this change is not made, the labeling cannot be guaranteed. each bottle in the desired position. And now the products are equipped with "automatic calculation of label length" function, this function can effectively make up for the above weaknesses. "Automatic calculation of label length" is an automatic control technology formed by the combination of PLC and servo motor technology. When the bottle on the conveyor belt passes the detection electric eye, the radius of the bottle is measured, and the most prominent point on the outer edge of the bottle is taken as the sticker. The sensing point of the labeling signal, that is, no matter how small the diameter of the bottle is, is the most prominent point on the outer edge of the bottle as the sensing point of the labeling signal, so that the distance between the electric eye and the peeling plate does not need to be adjusted mechanically. There is no need to adjust the labeling time at all, which is the automatic control principle of "automatic calculation of label length". This is also the first choice for people to have functions of the self-adhesive labeling machine.

In terms of the synchronization of control speed, in addition to the above-mentioned "automatic calculation of label length" function, the self-adhesive labeling machine should also automatically complete the synchronous adjustment of conveyor belt speed, marking speed, marking length, etc., which is also in line with traditional The difference between the self-adhesive labeling machine is the guarantee of the quality and stability of the labeling. The control speed of the traditional self-adhesive labeling machine is adjusted by human experience, and the difficulty of manual adjustment is that all actions are difficult to synchronize. Without synchronization, the labeling process will change frequently, resulting in poor labeling quality.

In the control system, the preferred control system (PLC + man-machine interface) is the main control system. Compared with the early single-chip computer (single-board computer), using a general-purpose PLC as the main control device can enable the PLC control system to achieve the following goals:

(1) More stable and reliable;

(2) The maintenance in the future is more convenient and the upgrade is simpler;

(3) It can be easily controlled online with the upper and lower stations.

In addition, it is also necessary to consider adding a vision system, which can perform real-time detection, control and alarm on the integrity of printing, the condition of word particles, and whether the label after labeling is present or not, and whether it is complete or not.

2. select basing on the conveyor speed, printing speed and output

When choosing a self-adhesive labeling machine, people often only pay attention to the output of labeling (that is, how many pieces can be pasted per minute), and fail to comprehensively consider the speed of label delivery, printing speed, and rolling speed. Of course, the labeling output covers other indicators, but other speed indicators play a key role in the quality of use and production development. From their analysis, people can observe the advantages and disadvantages of each mechanism and potential initiative, which is also the choice of self-adhesive. The labeling machine should be comprehensively investigated for the reason.

(1) The label feeding speed of the self-adhesive labeling machine is often not confirmed by the label width and printing speed when supporting the output of the self-adhesive labeling machine, only the highest output index in the manufacturer's sample It is also unreasonable to make a choice, because the maximum yield index given by the general manufacturer's sample is based on a certain label length and a certain printing method. Therefore, in the selection of the output of the self-adhesive labeling machine, the label feeding speed should first be investigated. Theoretically, the relationship between the label feeding speed and the labeling output is: Q=1000V/(L+a)

Among them: Q is the maximum labeling output calculated by the maximum label feeding speed, pieces/min; V is the maximum label feeding speed, m/min; L is the length of a single label, mm; a is the spacing between labels, mm.

For example, when labeling a bottle with a diameter of φ36, L=52mm, a=3mm, V=25m/min, then Q=454 pieces/min. That is, when you choose V=25m/min, and considering other factors, when the labeling length L=52mm, the maximum labeling output can only be in the range of 400 pieces/min, not to mention the speed increase or replacement of longer labels in the future.

In the domestic market, the maximum delivery speed of general self-adhesive labeling machine products is 38m/min, while companies with technical strength set the maximum delivery speed of products at 70m/min. In the case of standard output, it can also adapt to the change of label length (variable length); the high speed of label feeding is based on the quality of mechanical hardware, high component configuration and servo control technology, which cannot be manufactured by ordinary manufacturers, and its value is exactly Reflects the level of expertise of the manufacturer.

(2) The printing speed of the self-adhesive labeling machine. For the labeling machine used in the pharmaceutical industry, it is particularly important that the label can print the batch number in place. Therefore, when choosing the speed of feeding and rolling of the self-adhesive labeling machine, the printing speed of the equipped printing machine should also be considered, and the smallest one can be counted as the actual labeling production capacity value.

The batch number printed on the self-adhesive label is generally dominated by hot stamping in the pharmaceutical industry. Hot stamping is a technology that heats the prefix to print the text through the ribbon. Why is hot stamping the preferred method for printing batch numbers on self-adhesive labels in the pharmaceutical industry? Compared with the latest inkjet printing methods, hot stamping characters have low production costs and equipment maintenance costs; second, hot stamping characters will not occur similar to some inkjet printing devices. The odor emitted by the solvent will affect the printing. The circulation of the air-conditioning system; the third is that the ribbon can be recycled, which has an environmental protection side.

Although hot stamping has its own characteristics, it also has a weakness, that is, its printing speed is limited to a certain extent. The fastest speed of domestic hot stamping machines is generally 400 times/min. After this value, the printed text is not clear. Therefore, some people think that the maximum output of the self-adhesive labeling machine with hot stamping can only be set at 400 pieces/min, and the self-adhesive labeling machine with more than 500 pieces/min output should be equipped with inkjet printing.

3. select basing on the perspective of special use

When labeling bottles, there are often problems with special purposes. For pharmaceutical production, you may encounter: (1) Double-sided stickers; (2) Similar to the surface of plastic bottles, the label adhesion is reduced due to the release agent or There is a "bubble" phenomenon on the labeling surface. This puts forward more special requirements for the selection of self-adhesive labeling machines.

3.1. Aspects should be considered in the selection of double-sided stickers

When double-sided sticking of flat bottles, square bottles and round bottles is required, at least the following points should be considered:

(1) The label head can realize the adjustment of multi-dimensional space to ensure the accuracy of labeling, such as the adjustment of 6-dimensional space;

(2) The label head is designed with double pressure rollers to improve the tension of the label, so as to facilitate the labeling of long labels.

3.2. Considerations for the problem of "bubble" easily generated on the labeling surface

(1) The influence of static electricity should be eliminated. The bottle body can be electrostatically treated with a de-static ion fan, and the static electricity of the label can be removed with an electrostatic brush;

(2) Increase the labeling pressure of the label and increase the adhesion between the label and the bottle as much as possible;

(3) During the labeling process, make the label and the bottle in line contact as much as possible to completely remove the "bubble".

4. about the quality of the labeling

The generally accepted labelling quality requirements are:

(1) The labeling error is less than or equal to ±1mm, and this value can be achieved even if the overlapping position of the labeling is repeated many times;

(2) After sticking, the label and the bottle surface should fit together, and should be flat, without wrinkles and "bubble" phenomenon;

(3) The handwriting of the printed batch number is clear and recognizable, without overlapping and blurring, and the error of the batch number is <±1mm.

In order to achieve the above labeling requirements, in addition to label quality and reasonable operation, it is also related to equipment. Therefore, the following points should be considered in the selection:

(1) The flatness of the labeling mainly depends on the reasonable design of the rolling mechanism and the high-precision processing. Under the rolling pressure, the line contact between the label and the surface of the bottle must be ensured;

(2) High configuration requirements of drive components, because the core of the label feeding action is a high-precision and ultra-low inertia servo motor. In order to ensure the quality of labeling, the system uses closed-loop control, and the motor itself can always correct its own position. self-compensation;

(3) Detection methods and detection components are also the basis for ensuring labeling quality and labeling output. Manufacturers with technical strength have changed the imperfections caused by detection components only to detect label printing in the past, and now change the detection method. In order to measure the thickness, it uses the thickness change generated by the gap between the label and the label to control the operation of the servo motor, which is the best detection method at present, and it is more reliable;

(4) To achieve perfect labeling, the control of the whole machine is also very critical, especially the speed of bottle feeding and label delivery. In the selection control, it should be noted that the production speed signal can be sent to the system through synchronization, and then sent to the servo motor after analysis and calculation, and the running speed of the two is required to match;

(5) Component configuration, because today's high-speed labeling is based on the continuous operation of the machine, it requires each component to respond quickly, and all actions must be completed in an instant, which also requires the configuration of detection components. For example, for labeling servo motor, labeling motor drive, conveyor belt motor, delivery motor, separation motor, inverter, labeling sensor, label detection sensor, delivery stop proximity switch, programmable controller, man-machine operation Interface elements all have configuration requirements.