1. The power and transmission device of the screen printing machine.
1. Motor. Generally, screen printing machines use 4-level AC motors with voltages of 380V or 220V (220V is more convenient and widely used). The power depends on the machine. Large equipment can be driven by 2 or 3 motors respectively.
2. Air pump. Pneumatic screen printing machines generally require an air source above 6kgf/cmz. Air pump pressure can be divided into positive and negative.
3. Hydraulic pump. The power source of the hydraulic screen printing machine is a hydraulic pump.
4. Electromagnetic clutch. The electromagnetic clutch on the screen printing machine is either integrated with the motor or installed separately. Its function is to change the motor from frequent starts to constant rotation, so that the execution parts can move sensitively and avoid the influence of motor inertia. At the same time, it can be used as a first-level deceleration mechanism.
5. Reducer. Generally, a worm gear reducer is used, which has a large transmission ratio, small size and compact structure, and is used to transmit power, reduce speed, and adjust the direction and installation orientation of the input and output shafts. Belt reduction can also be used, but it must be before the worm gear reducer so as not to affect the phase relationship of the whole machine.
6. Speed ??regulating mechanism. Speed ??regulating mechanisms are divided into two categories: stepped and stepless. Most small and medium-sized computers use stepless speed regulating mechanisms.
2. The printing plate device of the screen printing machine.
The flat screen is relatively simple, consisting of a frame and a screen. The screen printing plate must be fixed on the printing plate device in the screen printing machine. During the printing process, it can be raised and lowered or lifted horizontally.
Lift-up screen printing machines generally adopt a hinged structure, and the lifting and lowering plate devices can be mechanical (such as cams, crank connecting rods, tension springs, counterweights, etc.) or pneumatic and hydraulic, supplemented by accessories. Heavy blocks.
The horizontal lifting and lowering device must ensure that the screen frame and the printing table are parallel, which can be achieved through mechanical parallel linkage rotation or motorized or pneumatic synchronous lifting.
1. Plate holder. It is required that the clamping is firm and the screen frame is not damaged at the clamping point. There are many clamping methods, but the most widely used method is clamping with a grooved body and a screw rod and a presser foot.
2. Printing plate lifting and lowering mechanism. Screen printing machines that lift up and down the printing plate generally use a cam mechanism, or add a swing rod mechanism; screen printing machines that lift up and down the printing plate generally use a cylinder guide pillar structure or a cam guide pillar structure. After each printing operation is completed, when the printing plate falls to the working position again, its relative position to the platform should remain unchanged. Therefore, the axial and radial clearance of the hinge rotary axis must be strictly controlled, generally not greater than 0.05mm: the radial clearance of the horizontal lifting guide column is generally not greater than 0.03mm.
3. Net lifting compensation agency. In order to avoid the adverse effects of the off-grid angle becoming smaller as the squeegee stroke gradually increases, a compensation mechanism can be added to the high-precision screen printing machine, generally in two forms:
a. The cam drives a swing rod to enlarge a slider, and gradually lifts the front end of the screen frame along with the printing stroke.
b. A tension spring is hung on the front end of the screen frame. At the same time, the squeegee device and the roller are pressed against the slope of the screen frame. At the beginning of the printing stroke, the roller presses the screen frame and the tension spring stretches to make the screen parallel to the working platform. As the printing stroke gradually increases, The tension spring gradually pulls up the front end of the screen to compensate for the off-grid angle.
3. Printing device of screen printing machine.
Squeegeeing is the main action for screen printing. It requires that the height of the squeegee and the squeegee pressure can be adjusted. In addition, it is required that the inclination angle of the squeegee can also be adjusted to ensure that it is at the best angle with the screen, usually 65°. ~85. . Ink return is the process of returning the ink to the starting end after scraping and evenly applying a layer of ink on the screen printing plate for printing again.
The scraping system and the ink return system are usually installed on the scraper carriage. During the reciprocating motion, the scraping plate and the ink return plate rise and fall alternately to realize the ink scraping and ink returning actions respectively. The rise and fall of the scraper is mechanically reversed on general flat semi-automatic machines, while pneumatic control is mostly used on precision semi-automatic flat machines.
The transmission of printing devices is mostly through belts, gears, worm gear reduction and stepless speed regulation systems, and some also use needle wheels, cam crank mechanisms, parallel four-link mechanisms or chain mechanisms. The former has a simple structure and is easy to operate, but the movement is not uniform enough; the latter has smooth transmission but a complicated structure. Its control system can be divided into two categories: organic and electrical control and gas-liquid electrical control.
4. Support device of screen printing machine.
The supporting device is the printing platform, which is used to fix the printing substrate.
The printing platform should have high flatness to ensure overprinting repeatability; the printing platform should have a print positioning device. In order to adapt to the requirements of substrates of different thicknesses and maintain a certain screen distance, the height of the platform should be adjustable. #For the convenience of plate alignment, the printing platform should be adjustable in the horizontal direction.
The printing platform of a typical semi-automatic flat screen printing machine is equipped with a vacuum adsorption facility to fix airtight sheet substrates such as paper, plastic film, etc.
5. The plate alignment mechanism of the screen printing machine.
Plate alignment mechanisms generally include light alignment, mechanical alignment, and electronic alignment. The plate registration mechanism can be placed in the supporting device or in the printing plate device, but generally semi-automatic machines are placed in the supporting device.
The movement of the platform during plate alignment is generally achieved by mechanical thread rotation, and should have reliable locking devices and displacement guides (dovetail grooves or guide keys, etc.).
6. Drying device of screen printing machine.
Because the ink layer of silk screen printing is very thick, the drying problem of ink is more prominent than that of ordinary printing methods. Single-color screen printing machines are often not equipped with a drying system. The workpiece is dried or dried in a drying box after printing, while automatic line or multi-color screen printing machines must be equipped with a drying device.
The settings of the drying system often need to match the ink used. For example, the WPB852A semi-automatic flat five-color screen printing machine uses far-infrared electric heating tubes for hot air drying. With the emergence of ultraviolet curing ink (UV ink), UV curing drying devices have been put into practical use.
7. Electrical control device of screen printing machine.
Electrical control devices generally have three control functions: working cycle control, negative pressure control, and squeegee position control for each working cycle. Web link