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How to more accurately determine the die-cutting pressure of new products

with the gradual recognition of product packaging personalization by the market, various box types with the symbolic meaning of slowing down the degradation rate of the enterprise have also become a symbol and culture of the enterprise. In the process of mass production of box type, die cutting is an essential processing means. For the whole die-cutting process, the control of die-cutting pressure is a core link of product quality control. Too much die-cutting pressure will cause damage to the die-cutting plate, and too little pressure will cause poor separation of boxes and pieces

because the die-cutting pressure of the die-cutting machine is greatly affected by the physical properties of pressure bearing materials and the properties of different die-cutting plates, it is difficult to determine the initial setting pressure. There are three main pressure transmission modes of the horizontal die-cutting machine, namely, four groups of crank connecting rod mechanism, wedge block cam mechanism and worm eccentric mechanism. No matter what transmission mode is used to provide die-cutting pressure, the final pressure should be transmitted and realized through the steel knife and steel wire on the die-cutting plate, that is, the die-cutting pressure is converted into the line pressure of steel knife and steel wire. In the operation of the die-cutting machine, the most important thing is to control the die-cutting pressure, but for different processing materials and box types, how can we set the die-cutting pressure quickly and accurately

1 theoretical calculation method

after the die cutting pressure is converted to line pressure, the pressure value is related to the total length of steel knife and steel wire, the effective line pressure and the characteristics of pressure bearing materials. The current general calculation formula is:

P = K L f

p - die cutting pressure (n)

k - correction coefficient (generally 1.3)

L - total length of steel knife or steel wire on the die-cutting plate (mm)

F - effective line pressure of steel knife or steel wire (n/mm)

but in actual production, the physical parameters such as tightness, thickness and fiber direction of materials are different due to different materials and environments, and the die-cutting pressure will change; In addition, the change of processing conditions will lead to the wear of steel knife and steel wire, resulting in the change of effective line pressure of steel knife and steel wire. In the calculation, it is always assumed that the steel knife and steel wire work under the best effective line pressure state, which leads to the error of theoretical calculation value. In addition, due to the incomplete level of the die-cutting plate caused by the manufacturing process of the die-cutting plate, and the different installation heights of the steel knife and steel wire caused by the machining accuracy error of the bridge height, the actual performance of the formula is reduced. Therefore, this formula cannot be used to determine the pressure of all die cutting plates

however, this formula still has very important guiding significance for the processing process of new production tasks, and plays a role in saving printing sheets and protecting die-cutting plates. The biggest practical value of the formula lies in the determination of the reasonable range of the initial pressure. Before the new die-cutting plate is used, the reasonable theoretical pressure value that the die-cutting plate can withstand for the first time can be calculated according to the parameter value required by the formula, rather than the reasonable actual pressure value of the die-cutting plate. From this formula, it can be seen that the calculation of die-cutting pressure and pressure bearing materials are mainly balanced by the correction coefficient, but using the same correction coefficient every time will lead to the difference caused by the change of pressure bearing materials

2 trial cutting method

in addition to the calculation method, the trial cutting method is also a simple method to determine the die cutting pressure. In fact, it uses an experimental process to determine the die cutting pressure of a certain box shape. This method is of great help to determine the pressure of the first processed product. Based on the experience of the operator, the trial cutting method estimates the die cutting pressure of new processed products. After finding a reference, gradually increase the die cutting pressure accordingly until 2/3 of the die cutting line of the die cutting sample is cut off. This process is called initial pressing. After the initial pressure value is determined, the pressure can be increased by 3 ~ 5T according to the characteristics of the pressure bearing material. After more than 90% of the steel knives and steel wires realize normal die cutting, the pressure can be increased by 0.1 ~ 0.3T until the die-cutting box can be separated normally. This process is called fine pressing

this method is time-consuming and labor-intensive, and has high requirements for the operator. If the initial pressure is too high, it is easy to cause damage to the die-cutting plate. If the pressure is too small, it needs repeated tests to reach the rated value, thus reducing the production efficiency. However, once a reasonable pressure value is obtained, this value has a very important reference value for future reprocessing, and it should be recorded one by one for next use. However, as the wear degree of the die-cutting plate is different, the effective linear pressure changes, resulting in the change of the actual die-cutting pressure value. Usually, the marked actual die-cutting pressure needs to be constantly modified to meet future applications

some people think that the calculation method can't be close to production at all, and it's almost useless to eat and a pity to abandon. At present, factories also generally use the trial cutting method to obtain the reasonable pressure value of new products. If the two methods are used together, it will bring certain economic benefits to the actual production

3 synthesis method

calculation is one of the oldest art situations in the history of human civilization. The algorithm can get the theoretical pressure value of the first pressure, and the trial cutting method can get the actual pressure value. If the reasonable actual value obtained by the trial cutting method can be used to deduce the correction coefficient in the calculation algorithm, then the correction coefficient of this kind of die cutting plate on this kind of material can be obtained. The correction coefficient is a variable value, which is mainly used to make up for the differences between different materials and the errors between the machining accuracy of the die-cutting plate. The correction coefficient of the same material can be determined more accurately through the actual production data of the same material, so that we can know how much pressure should be used for the first time in the die-cutting of new products, which can be closer to the reasonable actual pressure value

the test method is as follows: assuming that the gram weight of the first die-cutting is 300g/m2 white cardboard, it is known that the total length of the steel knife on the die-cutting plate is 1600cm, the total length of the steel wire is 1810cm, the effective line pressure of the steel knife used is 45n/mm, and the effective line pressure of the steel wire is 40n/mm

how to determine the die-cutting pressure value required for using 300g/m2 white cardboard die-cutting products

first, the theoretical reasonable pressure value of the product for die cutting is 187.72t through the calculation method, then the trial cutting method is used for die cutting, the initial pressure is set at 60% of the theoretical value, and the actual pressure value is 174.8t through continuous pressurization, and the pressure value is brought into the formula again to obtain the K value of 1.2. Therefore, in the die cutting of this kind of materials, the corresponding accurate pressure value can be calculated by using the formula k=1.2, which avoids the risk of trial cutting method and saves the production cost. The closest correction coefficient can be obtained by establishing a test table for different products of the same material, so as to obtain the ideal actual die-cutting pressure for the next new product

of course, this method cannot provide the same standard for all equipment, because the correction factor also includes the processing error of the equipment, and the wear conditions of different equipment are different. Therefore, the above tests can only be carried out on the same machine. It is best to take the average of multiple groups of actual data to calculate the correction coefficient of the material. The establishment of a correction system for different processing materials is of great help to the processing of new products at the cost of 0.77 euros/kg, which can accurately judge the pressure required for die cutting and save a lot of materials and time. In addition, because the wear of the equipment will lead to the change of the correction coefficient, and the effective service life of the die-cutting equipment is longer, its wear is also slower than that through the on-site inspection of the enterprise, review of the application materials, organization of the review meeting, etc. Under normal use, the correction factor can be re measured in a cycle of two years. If the equipment is used intensively, the measurement cycle can be shortened

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