1. The influence of the processing quality and assembly accuracy of each part

Judging from the single technical parameters of the die-cutting machine, the gap between the domestic die-cutting machine and the foreign die-cutting machine is small, but there is a large gap in die-cutting speed, accuracy, stability, and reliability. Mainly limited by the technical level of the domestic manufacturing industry, many parts are processed rough, the error range is relatively large, and the assembly is not accurate enough, which causes the machine to run fast and die cutting accuracy is not high enough. For example, the matching and manufacturing accuracy between the intermittent mechanism and the main drive system and chain row directly affect the speed of the machine. If the assembly accuracy is not enough, it will affect the die cutting accuracy and cause noise increase. Another example is the matching of the toggle pressure mechanism and the moving platform. Due to the relative motion, there must be a gap. If the gap is not determined properly, it will cause impact load, vibration, and noise increase, which will affect the speed and accuracy of die cutting.

2. The effect of paper speed and positioning mechanism

At present, the paper feeding method commonly used at home and abroad is continuous paper feeding, that is, a part of the front sheet and the back sheet always overlap together, and this method of sheet feeding is stable and fast. However, the paper feed speed is fast, and the paper will produce a large impact force when it leans against the forward gauge, which may easily cause the paper to curl or bounce, resulting in inaccurate positioning and reduced accuracy. Therefore, the ideal die-cutting machine should ensure the speed of the die-cutting while reducing the speed of the paper on the conveying table, thereby reducing the impact of the paper on the front gauge, ensuring accurate positioning, and improving the accuracy of the die-cutting.

The printed matter is positioned by the positioning mechanism before die cutting. The positioning mechanism of the die-cutting machine consists of a front gauge, a side gauge, a front gauge mechanism and a rear gauge mechanism. The positioning mechanism has a crucial influence on the accuracy of the die cutting machine.

Before the paper enters the gripper row, it is positioned by the front and side rules. The role of the front rule is to position the paper in the longitudinal direction. If multiple front rules are installed, only two of them are positioned, and the remaining front rules It must be precisely on the same horizontal line to play an auxiliary role, otherwise, it will cause over-positioning and reduce the positioning accuracy. The height of the front gauge is adjustable, and the height should be moderate during die cutting and positioning. If the front gauge is adjusted too high, it will cause the front edge of the paper to bend, which will affect the positioning accuracy. No positioning effect. Side gauges are used for horizontal positioning of paper. There are usually two side gauges, but only one is used during work. In order to ensure accurate positioning, the pressure of the side gauge pull roller should be appropriate. Excessive pressure of the paper pulling wheel will cause the side edges of the paper to bend; too little pressure may cause the paper to not be pulled in place, affecting positioning accuracy. In addition, because the positioning time is fixed, the length of the positioning time of the front and side gauges will also affect the positioning accuracy and thus the die-cutting accuracy. Therefore, the positioning time of the front and side gauges should be reasonably allocated.

After the paper is positioned, the paper feed row transfers the paper to the molded part for die cutting and indentation. The paper feed row is fixed on the intermittent conveyor chain. In order to ensure the accuracy of die cutting, it must stay in an accurate position. Therefore, when the paper feed row moves to the end of the cardboard, the front row of gauges drives the row shaft to a certain position to complete the front positioning of the paper feed row. When the conveying chain discharges the paper feeding teeth between the upper platform and the lower platform of the molded part, the rear regulating mechanism moves the shaft of the tooth row to the positioning point to achieve accurate positioning. Therefore, the front and rear gauge mechanisms directly affect the die cutting accuracy.

3. The influence of intermittent mechanism, chain and paper feed row

The movement of the paper feed row is an intermittent movement process, controlled by the intermittent mechanism. The intermittent mechanism of flat die cutting machine generally uses parallel indexing cam mechanism. Compared with other intermittent mechanisms, it has the following characteristics: reliable movement; smooth transmission; the law of motion of the follower depends on the contour shape of the cam; the turntable can achieve ideal expectations Movement and obtain good power performance, the positioning of the turntable in the intermittent period is completed by the curved groove of the cam, and no additional positioning device is required. When the machine is running at high speed, the cam profile is affected by the speed, acceleration, inertia size and direction of the follower, causing the machine to vibrate. This vibration is transmitted to the chain, and the rapid start and stop will cause the jitter of the paper feed row. , Thereby affecting the speed and accuracy of the whole machine. Therefore, on the basis of analyzing with dynamics, it is also necessary to dynamically design the cam profile to ensure the smooth movement of the intermittent mechanism itself.

The chain is a flexible piece, and the links are connected with pins, so the pitch error is large. Long-term use, due to wear, will naturally extend the chain and increase the error, which will bring unstable factors to the transmission, affect the position of the positioning point of the feeder row, and thus affect the die cutting accuracy. When working, the chain should not be too tight or too loose. If the chain is too tight, the wear will be accelerated and the service life of the chain will be shortened. If the chain is too loose, the vibration will be severe and the noise will increase.

The paper feed row is used to transport paper. The flat die cutting machine mostly uses solid row, which is easily deformed during the high-speed operation of the machine, which affects the positioning accuracy. Due to its large quality, it is in the process of rapid rotation and instantaneous stop , It will not be easy to stop due to large inertia, affecting machine operation stability and die cutting accuracy. Therefore, it is the direction of future development to change the solid tooth row to a hollow row with higher hardness. In addition, the gripper will produce noise when working, causing vibration of the tooth row, which will affect the die cutting speed, and will also affect other components. Generally, the following measures can be taken: (1) The gap between the plugs is as small as possible; (2) The gripper should be staggered from the rule plate; (3) The gripper angle should be adjusted appropriately. In addition, the pressure of the grippers will also affect the accuracy of the die cutting. Excessive pressure of the grippers will damage the paper; too low pressure will cause the paper to slip or slip off during the transfer process; the pressure between the grippers is not All may cause the paper to skew during die cutting.

4. The influence of chain guide

During the die-cutting process, the paper is driven by the chain. In addition to the cyclic rotation of the chain and the sprocket, the position passed by the chain is also positioned by the guide rail to control the movement direction of the chain and the tooth row. Therefore, when installing and debugging the guide rail, make sure that the guide rail has a proper thickness and can be embedded in the chain. The distance between the upper and lower guide rails must ensure that the chain passes smoothly. If the distance is too small, it will increase the transmission resistance and affect the transmission speed. In serious cases, it may even damage the machine; if the distance is too large, the chain will easily jump in motion and affect the transmission accuracy. Affect the precision of die cutting. In addition, the trajectory of the guide rail and the length of the chain also have a certain impact on the performance of the machine.

5. Influence of transmission system

The main transmission system of the die cutting machine is driven by the worm and the worm gear driven by the motor. The transmission performance of the main transmission system has a direct or indirect effect on the die cutting speed and accuracy. Worm gear is a kind of gear. Gear transmission has the characteristics of stable transmission, strong bearing capacity, good thermal processability, high efficiency and so on. The most common transmission gears are spur gears and helical gears. Comparing the two, the helical gears have good stability and a large coincidence coefficient. At present, helical gears are widely used in die-cutting machines, but the pressure angle will affect the stability of their transmission. When the worm gear and the worm are engaged at the dividing circle, the backlash between the gear teeth and the gear teeth is appropriate, the worm gear transmission is stable, the lubrication is sufficient, and the worm gear is in the best working state. Otherwise, too large backlash will make the worm gear transmission unstable and cause vibration; too small backlash is not conducive to the flow of lubricating oil and accelerates the wear of the gears. In severe cases, it will cause "top teeth" when the worm gear and worm are engaged, affecting the transmission Accuracy, which in turn affects die cutting speed and accuracy.

6. The impact of pressure mechanism

Die cutting is done under pressure, so the most important mechanism of the die cutting machine is the pressure applying mechanism. At present, the most widely used pressure mechanism in China is the double toggle mechanism, which has the transmission characteristics that the movable platform can reach the highest limit position (also called "dead point") twice during the crank rotation. During die cutting, the upper platform composed of the upper plate frame and the die cutting plate does not move, and the lower platform gradually rises from the lowest point to the highest point through the main transmission system and the toggle pressure mechanism, and reciprocates. When the movable platform reaches the "dead spot", the die-cutting pressure is maximum. At this time, the elbow is straightened, and the pressure will be transmitted vertically to the base. The connecting rod and crank are not stressed, effectively reducing the peak load of the connecting rod and crank. In order to ensure the quality of die cutting, the entire platform should be evenly stressed when pressurized. Therefore, the working surfaces of the upper and lower platforms must be parallel. Therefore, reasonable design and optimization of the length of components are particularly important. If the design is not reasonable, it will cause uneven die cutting pressure, excessive empty stroke and other adverse factors, affecting the speed and accuracy of die cutting.

7. Influence of die-cutting plate, die-cutting knife and rubber strip

The die-cutting mechanism is the core of the die-cutting machine, and the die-cutting plate, die-cutting knife and creasing line are the basic components of die-cutting. To ensure high-precision die cutting, it is necessary to select high-quality die-cutting plates, die-cutting knives, and indentation lines.

A good die-cutting plate requires uniform density, light weight, high hardness, good flexibility, easy processing, good flatness, firmness, and not easy to deform. It also requires that the performance of the die-cutting knife and the indentation line after inserting the die-cutting plate is reliable and stable, which can ensure that the new die-cutting knife and the indentation line can still be combined well with the die-cutting plate after multiple replacements of the die-cutting knife and the indentation line. At present, most domestic large and medium-sized printing companies use laser die-cutting indentation plate. Although this plate is easy to install, it is easily deformed by the influence of environmental temperature and humidity changes, which affects the accuracy of die-cutting. In addition, due to the relatively large die-cutting pressure, if the plate size is too large, the plate frame is not used or the plate is not firmly installed, it is easy to cause the plate table to move laterally during the production process. In addition, under huge pressure, the center of the horizontal version may be deformed, and the die cutting blade is prone to bending and other undesirable phenomena, resulting in changes in the specifications of the die cutting version and affecting the accuracy of die cutting.

With the diversification of packaging materials and products and the emergence of unique packaging designs, high-quality die-cutting knives for different die-cutting materials have become necessary conditions for ensuring the accuracy of die-cutting. The quality of the die-cutting knife mainly depends on the sharpness of the knife edge, the height error of the whole knife and the situation of the big knife bending. The sharper the knife edge, the smaller the height error of the entire knife, and the smaller the bending of the large knife, indicating the better the quality of the die cutting knife. In addition, the thickness of the die-cutting knife should be uniform. Uneven thickness or exceeding the error range will lead to difficult inserting, deformation or excessive looseness of the cutting line, which will affect the accuracy of die cutting. The height of the die-cutting knife differs depending on the die-cutting packaging materials. For example: when the packaging material is double corrugated cardboard, the peak knife is used; when the packaging material is single corrugated cardboard, cardboard or thinner paper, the low peak knife is better for stability.

In order to ensure smooth paper feeding, a rubber strip needs to be pasted at the main knife line, and the elastic recovery force of the rubber strip is used to push the imprinted printed matter out from between the knives to prevent the printing material from being stuck when die-cutting the indentation. When choosing a rubber strip, the height and thickness should be determined according to different products. Generally, the height of the rubber strip is about 1 to 3mm higher than the die-cutting blade, and the specific height should depend on the printing material. The rubber strip is too high, it is easy to cause the rubber strip to touch the warped paper surface when the pressure is closed, and the paper is displaced and the die cutting is not accurate. In addition, the hardness of the rubber strip should also be moderate. If the rubber strip is too hard, it will inevitably produce a large squeezing force on the die cutter during die cutting, which will deform the blade and affect the quality of the product. Insufficient, may cause "pasted version" or "loose version". Therefore, the thickness and height of the rubber strip should be selected reasonably according to the printing material, and the rubber strip should be pasted in an appropriate position to ensure moderate elasticity and reduce its adverse effect on the accuracy of die cutting.

There are many factors that affect the speed and precision of die cutting. To improve the speed and accuracy of die cutting and the stability and reliability of the die cutting machine, in addition to optimizing the design of the mechanism of each part, processing each part accurately, choosing the basis of each part reasonably In addition to materials, the ideal assembly accuracy is also crucial to improve the stability and reliability of the whole machine.

In addition, the accuracy of equipment installation and commissioning also directly affects its production speed, product quality, stability and reliability. Improper installation and debugging will not only reduce the speed and accuracy of the whole machine, but also bring unexpected consequences and troubles to the actual production. Therefore, it must be paid enough attention. The quality of machine installation and commissioning is related to actual operators. Therefore, it is necessary to actively train employees and improve their quality and technical level.

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