Practice of webbing hot stamping
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In many production processes of packaging printed matter, bronzing operations are often encountered, especially with the increasing demand for anti-counterfeiting, hot stamping anchorage markers have become more common. Colorful packaging products are easy to attract people's visual attention, but also improve the taste and grade of packaging products.
Modern mass-produced packaging is required to be completed on gravure and flexo presses. The material used is roll material and the production speed is fast, which requires hot stamping film to be produced quickly (up to 60 m/min). Complete 100% transfer in time. At the same time, since the bronzing operation only occupies a small position on each small package, the anodized aluminum bronzing material must be consistent with the speed of the printed matter when hot stamping, and if the technical measures are not taken, the bronzing material will be greatly wasted. Since the length of each roll of the printed material is large and the size of the bronzing film is small, it cannot match the production. Even if the lengths of the two materials are the same, there is a contradiction that the electro-aluminized aluminum must jump.
The flat-pressing and bronzing mechanism is a problem that is not easy to solve because it requires the printing material to stop periodically on the bronzing table, and each stop position should accurately reach the position of the hot stamping quality.
The printing material is in the normal direction. If it moves at a speed of 100 m/min, if it is moved at the same speed in the reverse direction, it can be a static state in the spatial position, that is, a double-roller swing frame can be used. Periodic positive and negative movements require that the length of the stroke of the forward and reverse movements be the same as the length of the print, requiring that the print space stop at a fixed point for a hot stamping time, but the mechanical reciprocating swing mechanism is generally realized by a crank link. The motion of the crank is obtained by the average speed of the eccentric. The speed curve of the crank motion is a sinusoidal curve, that is, the minimum speed is 0° at the starting point and 180° at the end point, and the maximum is at 90° and 270°. It is a non-uniform motion. The motion graphics are as follows:
Then, when the printed matter is stationary on the hot stamping workbench, it can only be stopped relatively immediately near the 45° and 135° phases in the working process, and the hot stamping operation cannot be completed. The AC servo motor is operated in a 360° cycle non-uniform speed mode to 180°. The working process has been programmed by software, and it has been tested and modified to make it relatively static from 45° to 135° during the working process, such as a hot stamping cycle time of 400ns (150 times/min). In the 180° return process, the 180° hot stamping process takes 200ms. If the phase is between 45° and 135°, the AC servo uses a non-uniform speed to reach the line speed for 100ms, and the hot stamping is more than enough. The motion graphics are as follows:
In 2002, the author saw the production of gravure printing equipment. There was a station with a round and continuous hot stamping mechanism. When the speed reached 100 m/min to 120 m/min, the hot stamping still works normally, and the hot stamping is also very clear. The speed synchronization and jumping step in the circular pressing operation can make the bronzing film not wasteful to use, and the method is simple and reliable. Using a small inertia swing arm, the swing is one quarter of the length of the packaged printed unit. The hot stamping plate that is heated during hot stamping presses the bronzing film and the printed matter against the support roller, under the dual action of pressure and heat. The transfer is realized. At this time, the bronzing film must run at the same speed as the printed matter. When the hot stamping is completed, the raised hot spot will leave. Before the next hot stamping, the electrochemical aluminum film is in the case of no pressing, and the bronzing can be performed at this time. The film is returned to a length, so that the hot stamping film can be fully utilized during continuous hot stamping, so that the hot stamping film is greatly saved. However, its structural characteristics only solve the problem of waste of electrochemical aluminum, but can not solve the problem of hot stamping of laser hot materials.
Because there are two problems that can not be solved before the round pressing and bronzing: one is how to solve the problem of the waste of the bronzing film: one is the quality problem of bronzing when working at high speed. If the above two problems can be solved, then the circular pressing mechanism itself The characteristics will be obvious, mainly due to the simple structure, small space occupation, short process adjustment time, low cost and easy to popularize technology.
The AC servo motor is used to process the paper feeding process of the flat press stamping machine. In the new design, we removed the aluminum alloy splint used for unwinding, making it easy to replace the new roll and remove the waste roll. The ordinary motor is wound by the torque slip method. Because of the precise positioning of the laser anti-counterfeiting mark in the hot stamping operation, the single-single motor is used to drive the feeding mode, and the eccentric shared pendulum is boldly used in the hot stamping intermittent feeding. The roller method greatly simplifies the original mechanism, and the number of AC servo motors used is reduced to six, which greatly simplifies the circuit.
Because the design is simplified, the use is convenient, the cost is reduced, and the web circular pressing and stamping mechanism can be used on both gravure and flexographic printing, so that the domestic web printing hot stamping production process has A practical mechanism and widely used in the printing industry due to lower cost.