Relevant problems in the selection of screen plane shapes
These premium quality tablewares bundle with cascading metallic dot design are created to effortlessly match the rest of your decorations. The disposable plates are a perfect pairing with the paper cups and napkins supply and are suitable for any season.
Perfect for graduation-themed parties
Tableware,Toilet Mat,Stain Resistant Toilet Rug,Classic Woodgraining Toilet Rug,U Shaped Toilet Rug HISMOK(SHENZHEN)TECHNOLOGY CO.,LTD , https://www.nbwill-trade.com
The screen shape is also the plane shape of the screen frame. The selection frame is generally based on the net content of the manuscript plus the width of the ink area to determine the size of the frame, and then consider what material the frame strip uses and how much material is used. The shape of the screen frame is mostly rectangular, and only a few rare shapes are selected when encountering special substrates.
For example: the handkerchief printing is square; the advertising printed on the finished umbrella is triangular or isosceles trapezoidal due to the influence of the umbrella bone; the large-scale color printing is selected as a hexagon to strengthen the frame capacity and prevent inward deformation; the concave barrel bottom, The bottom of the basin is round. In fact, the special screen shape is not only suitable for special printing when it is used to stretch the net, tension uniformity, screen printing resolution, ink volume, etc., especially when making fine lines and tone color printing with high mesh screen. It is also practical for ordinary planes. The following is explained from three aspects: screen force analysis, screen printing experiment and practical application.
1. Screen force analysis
The screen printing plate is an elastic plate. Both the stretched screen and the scratch printing deform the screen and require the screen to return to its original shape. The screen frame bears the restoring force transmitted by the screen. This restoring force can be regarded as the sum of the tension of the stretched net and the scraping component and the shearing force generated by the friction between the scraper and the plate during operation. Since the motion force is an instantaneous value, the scraping force can be manually controlled and the screen frame is stressed It can be regarded as the tension under static state. Judging from the 90 ° stretched net, within the limit of silk screen elasticity, the greater the stretched net tension, the tighter the screen and the more uniform the tension, the better the quality of the screen. However, the tension of the stretched mesh will not be transferred to the screen 100%, and the loss of tension is mainly lost in the deformation of the mesh frame and the fatigue of the wire mesh. In response to this contradiction, high-strength wire mesh and trapezoidal cross-section mesh frames have emerged and can be improved Screen quality. However, if the frame material is increased indefinitely, it will increase the weight and affect the actual operation. The deformation of the frame is proportional to its length. The longer the frame is, the greater the deformation and the greater the loss of tension. Therefore, the deformation of the frame is different for different frame shapes.
On the round mesh frame, each action point is subjected to the restoring force of the wire mesh in two directions, the total force of the restoring force is directed to the center of the circle to achieve balance, so no inward deformation occurs. The stress on the junction of the hexagonal mesh frame remains unchanged, and the length of the six sides is relatively short, subject to the vertical resultant force to minimize deformation. The square mesh frame has the same side length, which is the least deformed in the rectangular mesh frame, and the tension uniformity after deformation is the best. The smaller the ratio of the short side to the long side of the rectangular screen frame, the greater the deformation, and the greatest influence on the uniformity of the entire screen tension.
2. Screen printing experiment
step:
1. Use a 2cm × 2cm metal square tube to bend two semicircular frames with a diameter of 40cm on a round bending machine, and then weld them together. The same material is used to make hexagonal, square and rectangular net frames.
2. After making the net frame, sand it, apply the glue twice, and choose 300 mesh wire net to stretch the net on the same stretch net machine, the tension is about 8kg. The screen version after being stretched is allowed to stand for 3 to 4 days.
3. The blank version scratches out 4 pieces of field.
4. Use 60 lines from 1 to 9% to make a tune-up picture. Make the printing plates of the same content on the four screen frames, and use each plate to scrape two clearest tone maps on 3mm white glass. Compare samples printed on screens of various shapes.
Experimental result: The solid ink and the uniformity of the rectangular screen are slightly worse, the dots are deformed, they are not complete enough, and the tone is narrowed. The quality of other screen samples is close to the same.
3. The practical application of screen shape
The round and hexagonal screen frames are stretched tightly, the tension is even, and the printing effect is good. However, in practical applications, the production of round screen frames is to be bent by a round bending machine. The process is complicated. The effective printing area is an inscribed rectangle. Material is wasted; although the hexagonal mesh frame is welded with straight edges, it has many welding points and the angle is difficult to control. There are also problems with the round frame and lack of practicality. Only the square version has the advantages of the above version, and the processing process is the same as the rectangular version, so it is better to choose a square with a side length of 1: 1 or a rectangle with a side length ratio close to 1: 1 when making a screen frame.
When I was just engaged in screen printing, I used 13 large, medium and small screens with different shapes to make a batch of large-scale maps. In order to be faithful to the manuscript and meet the mathematical accuracy in the figure, the screen prints out a zigzag square grid, thin contours such as dense hair, clearly reflecting rivers, beaches, roads, residential areas, etc. Heap, all over the sky.
Turn over the printing record in success and failure, and count the success rate of each numbered screen. It was found that the square plate printing had the highest success rate and the best quality. After analysis and testing, all the layouts were changed to 80cm × 80cm, 90cm × 90cm, 100cm × 120cm, and 12 groups of screens in 3 groups were recycled. When typesetting, as many pieces of content as possible are put together, or a content is arranged several times to form a layout. The pattern that cannot be stitched is printed with a large version of the small picture. It is also worthwhile as long as it can succeed.
Due to the change in the shape of the screen version, the monthly monthly screen printing task was as many as 80 blocks, and 3000 sheets of paper were opened, with a success rate of 100%. Its screen printing accuracy is positive error 2 ‰, and negative error is zero. The content of the picture is clear, the lines are smooth, and the characters are full. Afterwards, the author used a nearly square screen to make the tone flower and bird four-screen effect, which also laid the foundation for future large-scale color screen printing.
Graduation Party Supplies--paper platesnapkin cocktail napkin are designedwith graduate elements, such as grad capdiplomabook and so on are clearly printed.
As elegantgraduation decorationsthey will dress your table special and suprise your guests to make the party more fun and attractive.