At present, advanced die cutting machines and hot stamping machines are becoming intelligent. Multifunctional, large format, high speed, high precision, high stability and on-line development. The domestic flat die cutting machine is quite close to the world's advanced level in some aspects, but there is still a certain gap in speed and accuracy, especially in machine stability and reliability. In the technical indicators of automatic die cutting machines, the speed and accuracy of die cutting machines are important technical indicators. Speed ​​directly reflects the production efficiency, and accuracy marks the quality of products. Improving accuracy while increasing speed is a difficult problem for post-press packaging equipment. The following further discusses the flat die-cutting automatic die-cutting machine, which is for reference only.
Accurate positioning of variable speed paper feed
According to the paper running mode, the automatic paper feeding section can be divided into three types: intermittent, continuous and variable speed paper feeding. At present, the continuous paper feeding method is widely used at home and abroad, that is, a part of the front sheet and the rear sheet are always overlapped together. This method of paper feeding is stable and the speed is high. Under the same die cutting speed, assuming that the paper has the same settling time at the front gauge, the intermittent paper feed speed is much faster than the continuous paper feed speed. When the paper feeding speed is accelerated, the paper will have a greater impact by the forward gauge, which may easily cause the paper to bounce or curl, resulting in inaccurate positioning and reduced accuracy. In the case of equal paper feed speed, the positioning time of intermittent paper feed is much shorter than that of continuous paper feed. The problem of unstable positioning of the paper on the front gauge and side gauge will also occur, which will also cause a decrease in accuracy. If the intermittent paper is to have sufficient paper stability, it is necessary to reduce the speed of the machine, thereby reducing the die cutting ability. Therefore, intermittent paper feeding is generally only used for small-sized and low-speed machines, while continuous paper feeding is mostly used for large-sized and high-speed machines.
In recent years, variable-speed paper feeding methods have been adopted on high-speed die-cutting machines. The working principle of variable-speed paper feeding and continuous paper feeding is basically the same, but a paper feeding speed-changing mechanism is added on this basis. If the average speed of the paper feed is equal, the positioning time of the variable speed paper feed and the continuous paper feed is the same, but the speed of the variable speed paper feed will change periodically at each paper feed step speed. When the paper reaches the front gauge, the paper feed speed reaches the minimum, the paper has little impact, and the positioning is accurate, which is beneficial to improve the die cutting speed and accuracy.
Effect of gauge body parts on speed and accuracy
The accuracy of the product mainly lies in the die-cutting part of the automatic die-cutting machine, and the gauge body parts play a key role here. Before the paper enters the gripper row, the gauge body accurately positions it so that during the die-cutting process, the cut and the indentation line are at the same position on each piece of paper, meeting the requirements of high die-cutting accuracy. The positioning of the paper on the regulatory components requires accurate positioning in the front, rear, and left and right directions, which are guaranteed by the front and side regulations, respectively.
The paper after positioning must also have a high-precision paper transfer mechanism, that is, the gripper row body accurately transfers the paper to the die-cutting indentation plate for die-cutting. In order to ensure the accuracy of die cutting, it is necessary to ensure accurate transmission and ensure that each row of teeth stays in an accurate position. The accuracy and stability of the dental row body play a vital role in the accuracy of die cutting, and its movement, rest time and stability are determined by the intermittent mechanism of the die cutting machine. [next]
Effect of intermittent mechanism on speed and precision
The intermittent mechanism of the flat die-cutting machine generally uses a parallel indexing cam mechanism. This mechanism is a conjugate cam mechanism. Compared with intermittent motion mechanisms such as groove wheels and incomplete gears, it has good motion characteristics and smooth start and stop. The vibration noise is small and the structure is compact. It is widely used because of its advantages such as convenient processing. When the machine speed is high, the cam profile is affected by the speed, acceleration, inertia size and direction of the follower, which causes the mechanism to vibrate, thereby making the paper feed row work unstable. Therefore, on the basis of designing with kinematic principles, it is also necessary to use mechanical dynamics to dynamically design the cam profile to ensure that the intermittent mechanism itself moves smoothly. If the movement of the intermittent mechanism itself is not stable, the transition to the chain, coupled with the rapid start and stop caused the tooth row body to shake, resulting in low speed of the whole machine, and the accuracy is also greatly affected. In addition, the movement law of the intermittent mechanism is also very important. After the sine curve is improved, the speed is lower at start and stop, and the movement is relatively stable.
The intermittent mechanism stroke angle also has a great influence on speed and accuracy. The greater the stroke angle, the smoother the machine and the higher the machine speed. Assuming that the die cutting speed is constant, the longer the movement time of the intermittent mechanism (the greater the stroke angle) and the longer the movement time of the gripper row, the lower the average speed of the row movement and the smoother the movement, the better the accuracy.
Although the positioning mechanism of the die cutting machine produced by each company is different, the basic principle is the same.
The accuracy of die cutting is divided into side accuracy and front accuracy. The gripper tooth row mechanism is composed of a gripper row body and a connecting chain mechanism. The gripper tooth row structure is reasonable and the precision is high, which is very important for the die cutting accuracy. In order to eliminate errors in the length direction of the tooth row, the side positioning mechanism of the tooth row generally adopts one side for fixed positioning and one side for movable positioning. In order to improve the side accuracy, the fixed positioning side of the row should be close to the fixed side positioning plate, and there should be no gap under the action of the movable side positioning compression spring. Assuming that there is no error in the work of the side pull gauge, the fixed-side positioning and the paper margin on the side of the pull gauge are fixed values, and the length error of the tooth row has no effect on the side accuracy. On the contrary, if the pressure of the movable side positioning compression spring is insufficient or other factors make the row of teeth close to the fixed side positioning plate and there is a gap between the positioning plate, then to solve the side accuracy problem, in addition to improving the accuracy of the side gauge, it must also be eliminated Positioning gap error on the fixed side of the row of teeth.
In addition, the position of the side pull gauge to pull the paper, that is, the distance from the paper edge of the front gauge, also affects the side accuracy. If the distance between the pull gauge of the automatic die-cutting machine and the paper edge of the front gauge is the same as the pull gauge position of the matching offset press, the paper edge tilt error can be basically eliminated.
There are many factors that affect the accuracy of the front of the product: â‘ The working stability of the intermittent mechanism, especially the stability of the start and stop of the intermittent mechanism, directly affects the stability of the tooth row stop state, thus affecting the front accuracy. If the intermittent mechanism wears, it will also cause the tooth row to shake during the stop or start process, thereby affecting the accuracy before die cutting.
â‘¡After a long time running of the front block gauge body, its motion stability determines the change of the front and rear position of the paper, which affects the front accuracy.
â‘¢ The front and rear positioning blocks that play a role in positioning the grippers should have good strength and stability to ensure that each set of teeth is positioned at the same front and rear positioning points.
â‘£The length error of the tooth row chain and the elongation of the chain through wear will affect the position of the positioning point of the tooth row, thus affecting the front accuracy. Yuyin's products are all imported from Germany. For example, MY1050A and MY1060 die-cutting machines are designed with a unique mechanism to eliminate the chain length error and help to improve the die-cutting accuracy. The group of teeth is positioned at the same front and back positioning point.
â‘£The length error of the tooth row chain and the elongation of the chain through wear will affect the position of the positioning point of the tooth row, thus affecting the front accuracy. Yuyin's products are all imported from Germany. For example, MY1050A and MY1060 die-cutting machines are designed with a unique mechanism to eliminate the chain length error and help to improve the die-cutting accuracy.
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