The process of die cutting and creasing process is:
Previous version → Adjust the pressure → Determine the rules → Stick the rubber → Test pressure die cutting → Formal die cutting → Clean up the waste → Finished product inspection → Point packaging.
Processing technology
Take the main object of die cutting and indentation processing-carton as an example, generally need to go through the process of opening → printing → surface processing → die cutting and indentation → box making.
Before the die-cutting indentation, a stamping plate is to be made, and the grid position of the stamping plate must match the printing grid position; and then the post-printed cardboard is processed on the die-cutting machine using the stamping plate technical process. The manufactured stamping plate is installed and fixed in the plate frame of the die-cutting machine, and the position is initially adjusted to obtain the preliminary die-cutting indentation effect. The operation process is called the upper plate. Before publishing, it is required to proofread the die-cut and indented version, and confirm that it meets the requirements before starting the publishing operation. Then adjust the layout pressure. It is generally carried out in two steps. First adjust the pressure of the steel knife: after padding the paper, start the press several times, the purpose is to flatten the steel knife, close to the backing plate, and then use cardboard with an area larger than the die cutting plate (usually 400 ～ 500g / m2) Perform pressure test, according to the cutting marks cut by the steel knife on the cardboard, adopt a method of gradually increasing or decreasing the number of pads in part or all to make the pressure of each knife line on the layout uniform; then adjust the pressure of the steel wire; the general steel wire It is 0.8mm lower than the steel knife. In order to obtain the ideal pressure for the steel wire and the steel knife, the pressure of the steel wire should be carried out according to the nature of the molded cardboard. When the adjustment only considers the thickness of the paperboard as the main factor, the thickness of the backing paper is determined by the theoretical calculation method or empirical estimation method based on the test based on the thickness of the pressed paperboard.
The formula for calculating the thickness of potential paper using the theoretical calculation method is as follows:
X = (steel knife height-steel wire height)-h
In the formula: X is the thickness of the backing paper; h is the thickness of the pressed cardboard.
The rule is used to determine the position of the processed cardboard relative to the stencil in the die cutting and indentation process. After the plate pressure is adjusted, the template should be fixed to prevent misalignment in the molding. When determining the position of the rule, it should be reasonably selected according to the product specifications, and generally the principle of centering the molded product as much as possible. After determining and pasting the positioning rules, you should first try to press a few sheets and carefully check. The folding carton shall also be tested for molding specifications and quality.
The rubber sticks to the main steel blade of the template. On both sides, the elastic restoring force of Linan rubber can push the cardboard separated from the die-cutting part out of the cutting edge. The rubber should be 3 to 5mm above the blade.
After all the adjustment work is ready, the samples should be molded first, and a comprehensive inspection should be conducted to see if the product indicators meet the requirements. After confirming that the inspected items have reached the standards, the samples can be officially started and the production can be officially started. Every working day, the product requirements should be checked again in order to find and deal with the problem as soon as possible.
For the products after die-cutting and indentation processing, the excess edge material should be removed, which is called waste removal, also called blanking, chip removal, tearing edge, core pushing, etc., that is, the box core is removed from the bad material and cleaned. The cuts of the products after cleaning should be smooth and smooth. If necessary, sand the paper to polish the cuts or use a scraper.
After cleaning, carry out finished product inspection. After passing the product quality inspection, carry out point packaging, and remove the defective products from the points. The error should not exceed 2 to 10,000.
Process parameters and their effects
The main process parameters in die-cutting indentation processing are die-cutting pressure, working width and die-cutting speed.
The working capacity of the molding machine is determined by the size of the die-cutting pressure. In the molding process, due to the different processing objects and various requirements, the force required for the molding should be calculated in advance, so as to select and adjust the machine and guide the molding process .
There are many ways to determine the die cutting pressure. The theoretical calculation formula of die cutting pressure is as follows:
P = KσA
In the formula: P is the force required for molding; σ is the shear stress value per unit area in the molding, and its reference value is shown in Table 13-1; A is the actual area of ​​the molding separation surface, which can be calculated according to the thickness and circumference of the die cutting material; K is a coefficient that considers the actual conditions of the molding process and various technical factors. The value of K ranges from 0.76 to 1.34.
In the actual production of the factory, the value of the die-cutting force F per unit length is often determined by the test method, and then the size of the die-cutting pressure is calculated. That is, a steel knife and a certain length are installed on the press for the test material. Steel wire, then put the cardboard to be processed, pressurize the cardboard until the required line mark is cut and pressed; write down the pressure reading at this time, repeat 10 times, take the average value, and then measure Pressure P; divided by the total length of the incision and the pressure line l, you can find the average die cutting force per unit length F = P1 / l.
Cardboard thickness (mm) ＜ 0.5 ＜ 1.5 ＜ 3.0 ＜ 4.5 ＞ 4.5
The shear stress value σ (kgf / mm2) per unit area during molding is less than 1411 ～ 1310 ～ 129 ～ 10 ＜ 9
The required die-cutting pressure can be calculated by the following formula:
P = K1 · L · F
Where: P is the die-cutting pressure; L is the total length of the periphery of the die-cutting (including the incision and crimping line); F is the die-cutting force of the unit length of the incision and crimping line; K1 is the coefficient that considers various unfavorable factors in actual production. K1 = 1.3.
The size of the working width reflects the working capacity of the die cutting machine from another angle. According to the size of the processing width, the die cutting machine can be divided into different specifications such as full sheet, folio, four-fold, eight-fold, etc. Different manufacturers are slightly different. The molding speed is related to the working frequency of the die-cutting machine, and is a process factor that directly affects the productivity of the die-cutting indentation, and generally speaking, as the molding speed increases, the die-cutting pressure will also increase.
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