Each SPS® STOP cylinder screen printing machine has a unique PEH (pneumatic, electric, hydraulic) squeegee system. Once this innovative technology and precision structure came out, it has become the object of many screen printing equipment manufacturers to imitate, but to this day, there is no other technology comparable to it, and therefore, SPS® still firmly holds the market leadership .
In the process of designing the squeegee system of the high-speed cylinder screen printing machine, the biggest problem faced by engineers is how to prevent the squeegee from touching the gripper under the premise of ensuring the rapid start of the printer, because this will not only cause paper printing The initial (first few centimeters) beating will also cause damage to the screen and squeegee. Generally speaking, the squeegee must be activated after the gripper passes, but it must be fast enough to avoid too large a gap in the gripper.
The traditional mechanical system is composed of a cam and a roller linked to it, but as the speed of the equipment increases, the defects of this system become more and more obvious: it will cause the paper to jump during the first 3cm printing, and the doctor blade The screen can be damaged when falling from above the roller gripper.
This is because, on the one hand, in a system controlled by a cam, the doctor blade will descend at the front end of the gripper and stop after 15 mm of the turning point. However, when the cylinder is running at high speed, the descending motion of the squeegee will impact the screen and scratch the mesh at the root of the gripper (Figure 1). At higher operating speeds, the doctor blade will even fall directly on top of the gripper.
(Figure 1 The squeegee system controlled by the cam drive. At the beginning of printing, the squeegee blade will cut under the front end of the nip, and then slide down to the cylinder. It is easy to cause damage to the screen and uneven jump of the ink layer when the device is running at high speed. )
On the other hand, it is caused by the physical influence of the squeegee driving cam on the roller. During the downward movement of the doctor blade (at the beginning of printing), cam control can cause a sudden movement of the roller, thereby transferring a certain amount of vibration to the doctor blade (Figure 1, Figure 2).
(Figure 2 During the downward movement of the doctor blade (at the beginning of printing), the cam control causes a sudden movement of the cam roller, thereby transferring a certain change to the edge of the doctor blade.)
In response to the above problems, the engineers of SPS® Company created the hydraulic pneumatic electric squeegee system, which skillfully overcome the technical problems that have plagued the screen printing industry for many years. This automatic system completely abandons the mechanical linkage, and can maintain the linkage with the printing equipment.
SPS®PEH squeegee system is based on unique engineering principles and has the following characteristics:
The pneumatic and hydraulic drives are used to drive the squeegee blade, so the squeegee blade can be fine-tuned precisely, and the timing and speed of the blade can be adjusted according to the needs, not between the roller drive device and the squeegee blade The impact of motor relationships.
The first step of the squeegee movement starts from the turning point of the screen. At this time, the squeegee has enough time to approach the screen smoothly, keeping light contact with the screen while maintaining an appropriate distance from the jaw. With the rotation of the printing cylinder, a very important second step, that is, the printing process in the true sense also starts and is behind the nagging teeth, and this important step is that the beginning of printing is electronically controlled with the cylinder The linkage of the drum, in addition to being able to stably press the mouth gap set by the operator, and at the same time keep the printing tolerance within the minimum range (Figure 3).
(Picture 3 SPS® PEH squeegee system cooperates with SPS® STOP cylinder. When printing starts, the squeegee picks the paper teeth and then lowers the knife, ensuring the pressure of the squeegee is stable while protecting the screen and the ink layer uniformly and very well. To control the mouth gap.)
Once the squeegee touches the surface of the cylinder, it will accurately transfer the pressure set by the system to the screen without any fluctuation. Pneumatic and hydraulic synchronous drive can make the driver fall back into a non-compressed hydraulic buffer slowly, and through precise pressure control, make it float in a medium height position.
Setting the pressure of the squeegee and keeping it stable during the printing process and adjusting the height of the squeegee are two separate tasks. As long as the doctor blade is within the hydraulic buffer range (with a tolerance of 2 to 3 mm), the system can control the actual printing pressure through a pressure gauge or digital pressure gauge. The operator only needs to determine its strength and the rest of the work The system can be completed automatically.
This unique squeegee control system can provide users with more flexibility: users can change the starting point of printing and the gap of the gripper as needed. Different types of SPS® STOP cylinder printing presses can also pre-select different lengths of squeegee start path.
In addition, SPS® can also provide users with other optional equipment to improve the productivity and printing quality of printing presses.
Each time the squeegee is changed, the system can automatically set the height of the squeegee blade, so that the edge of the substrate is always parallel to the printing cylinder without being affected by the technical proficiency of the operator.
In addition, the system has the advantages of being fast, accurate, and reducing the wear of the rubber squeegee during the printing process (Figure 4).
(Figure 4 The SPS® PEH squeegee system is fully automatic controlled and the setting is very simple.)
The SPS® C105TM doctor blade (RKS is proprietary to SPS®) combines the dual advantages of carbon fiber and high-quality scratch-resistant rubber. During the printing process, the stability of the carbon fiber can ensure the consistency of the blade angle, coupled with the good performance of the SPS®PEH squeegee system, users can get unparalleled printing accuracy, especially when printing fine lines and halftone dots Figure 5). If necessary, the easy-to-operate pneumatic ink knife lock can be easily interchanged with the standard rubber scraper bracket.
(Figure 5 SPS®'s proprietary C105TM squeegee combines the dual advantages of carbon fiber squeegee and high-quality scratch-resistant rubber to achieve and guarantee the accuracy of fine lines and halftone dot printing.)
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