1.1 Feida section
1.1.1 Motion analysis of paper leaving the pile
When the printing press is running, through the suction and blowing of Feida, the paper is separated one by one from the paper stack and transported forward. From the appearance, the paper seems to be sucked up, is this actually the case? The following detailed analysis of the paper separation and transmission process.
For paper to move upward, there must be an upward force. So how do upward forces arise? In the actual process, the paper is sucked up by the suction nozzle, but if the upper and lower paper stick together, the upper paper cannot be separated. Break through the stack of paper again, so that there is air between the upper and lower paper, the paper on top can be separated. The air between the upper and lower sheets of paper is a prerequisite for separating the two sheets of paper. If the suction nozzle does not inhale, the paper cannot be separated, so another prerequisite for separating the paper by inhaling the suction nozzle. Summing these two conditions together leads to the conclusion that air is a prerequisite for separating paper, but there is no pulling force in the air, so the concept of "paper is sucked up" is wrong. So how does paper get up? In the actual process, Feida is equipped with a lot of nozzles and suction nozzles. The nozzle blows under the paper, and the nozzle sucks under the paper. As a result, the air under the paper is increasing and the air above the paper is decreasing. Just like a balloon, the more air you blow in, the bigger the balloon will swell. At the same time, the paper will be "swelled" by the air below. In the following, the paper will be further analyzed theoretically.
(Figure 1.2)
The surface of any object in the air is under air pressure. In general, the pressure in the air is one atmospheric pressure, and the pressure on the surface of the paper stack is also one atmospheric pressure. The suction nozzle sucks the air and reduces the amount of air, which makes the paper The air pressure is below one atmosphere. The pressure under the paper is generally less than one atmospheric pressure (mainly due to the uneven air gap between the two papers). The blower blows inward, and the amount of air continues to increase, so the "top force" on the paper above increases. When the top force below is greater than the pressure above, the paper has the possibility of separation. In theory, if the lower top force (p2) is equal to the sum of the upper pressure (p1) and the weight of the paper (w), that is, p2 = p1 + w, then the paper can be separated. However, due to the non-uniformity of paper weight and the acceleration of paper separation in the actual process, the above formula needs to be changed to p2-p1> w, and the difference between the top force and the pressure above is called pressure difference , Denoted as p. So p = p2-p1> w. Therefore, the pressure difference is the essential reason for the paper to separate and drive forward. Without the pressure difference, the paper will not separate and will not move forward with the nozzle. So the paper is topped up, not sucked up.
1.1.2 Free state of paper
In order to separate the paper on the stack, it is necessary to create a condition where the pressure difference exists, that is, there must be air between the upper and lower paper. In addition, due to the requirements of printing machinery transmission. The surface of the paper should be flat and the front opening and sides should be even. Only in this way can we lay the foundation for forward conveyance of paper. This state of paper on the pile of paper is called the free state of the paper. It is defined as: â‘ there is no resistance between the upper and lower papers (not including the gravity of the paper); â‘¡ the surface of the paper stack is flat; â‘¢ the front opening of the paper stack is flush; â‘£ the side opening of the paper stack (regular side) is flat Qi.
1. There is no resistance between papers (not including gravity). If there is resistance, it will destroy the formation conditions of the pressure difference, making it difficult to separate the paper. There are many forces between the paper, such as electrostatic attraction, ink adhesion, and local resistance caused by the warpage of the paper surface (the deformation of the paper caused by the ruffled edge or knocking caused by the damp paper).
2. The paper surface is smooth. The flat surface of the paper creates conditions for air to enter, especially where the nozzle is in contact with the paper. This is why when adjusting the feeder, the contact area between the feeder and the paper is always leveled (using padding or other methods), and the flat surface of the paper creates good conditions for the subsequent movement of the paper. The causes of the uneven surface of the paper are: the unevenness of the paper itself, the unevenness of the paper and the inequality of the paper table.
3. The front of the paper is flush. The front opening of the paper is flush to create conditions for the paper to be positioned at the front. If the front edge of the paper is severely uneven, the paper cannot be accurately positioned in the front gauge, and it may also cause paper feed failure. The reason for the uneven front edge of the paper: First, the cutting accuracy is not high (machine accuracy, inside and outside knife edges, cutting technology, etc.), second, the paper surface is warped, and third, the error is too large when breaking the paper.
4. The side of the paper is flush. The flush side of the paper (by the ruled edge) is a prerequisite for ensuring the position of the side. If the sides of the paper are quite different, the paper cannot be accurately positioned in the lateral direction. The cause of the uneven side opening is the same as the uneven front opening of the paper. One thing to add is that the front edge of the paper and the pull edge should be at right angles.
It can be seen from the above analysis that the free state of the paper is the first hurdle for the accurate, smooth and continuous separation of the paper. If the free state of the paper is destroyed, the paper cannot be transported normally. So the key is how to make the paper into a free state.
(Figure 1.3)
1.1.3 Feida's ideal working condition
Feida is one of the most important parts of the paper conveying part, and it is also the most adjusted place. The function of Feida is to deliver the paper on the paper sheet one by one, accurately and smoothly to the receiving roller. Nevertheless, there are still strong rules to follow in the adjustment process. If you have mastered these laws, you can easily adjust them.
(Figure 1.4 The relative position distribution of each part on the feeder on the paper) [next]
Each component on Feida has its specific role. Accurately grasping the role and motion relationship of these components is the premise of adjusting Feida. The following is an analysis of the role of Feida components.
1. Paper suction nozzle. The function of the paper-separating nozzle is to suck up (still use "sucking" here) the top sheet of paper in the stack, and pass it to the paper-handling nozzle.
2. Pass the paper nozzle. The function of the paper suction nozzle is to transfer the paper sucked by the paper separation nozzle to the paper receiving roller on the paper feeding board.
3. Presser foot. The function of the presser foot is to press the paper under the paper sucked by the separation nozzle to prevent the paper below from being skewed or double; the second is to control the height of the paper stack. Since the paper on the paper stack decreases one by one during printing, if subsequent paper is not replenished in time, the printing cannot be performed continuously. Therefore, the paper stack must always be maintained at a certain height. The ideal situation should be to take a piece of paper, and the stack of paper will increase by the thickness of a piece of paper. However, because the paper is relatively thin, the detection sensitivity needs to be very high, which is actually unnecessary. Under normal circumstances, the paper stack is always maintained at a fixed height, but when the thickness of the paper changes, the height of the paper stack should be adjusted accordingly (by adjusting the height of the presser foot); the third is to create conditions for the formation of pressure difference. There is a blow hole on the presser foot plate. After pressing on the stack of paper, it blows air under the first sheet of paper, thereby increasing the pressure difference. The fourth is safety. Once the stack motor fails, the presser foot will touch the limit switch to prevent the stack from continuing to rise.
4. Blow mouth. The function of the mouthpiece is to blow the top papers of the paper stack, creating a pressure difference formation condition for the paper separation nozzle.
5. Tablet or brush. The function of the tablet or brush is to prevent the tail of the second sheet of paper from being blown too high by the mouthpiece, so that the presser foot cannot accurately press the second sheet of paper; the second is to prevent double or multiple sheets.
6. Press block. The function of the pressing block is mainly to press the back corner of the paper to prevent the paper from floating due to blowing, and also to prevent the air outflow between the papers, which is conducive to the formation of the pressure difference.
7. Side blowing mouth. Side blowing nozzles are generally installed in the front corner of the stack. The main reason is to loosen the parts of the paper that cannot be reached by the presser foot.
8. Paper blocking tongue. The paper blocking tongue is installed at the front opening of the paper stack, and its main function is to prevent the top sheets of the paper stack from drifting, so as to prevent the front opening of the paper from being uneven and destroying the free state of the paper.
9. Static eliminator. The static eliminator uses high-voltage discharge to eliminate static electricity on the surface of the paper to prevent double or multiple sheets.
1.1.4 The interrelationship between the components on Feida
Although there are many parts on Feida, they are not disorganized. The first is that they must maintain a certain mutual relationship in motion, and secondly, each component must be in a normal working state.
Through the analysis of the function of each part of Feida, we can deduce the mutual motion relationship between each part. Briefly described as follows (see Figure 1.5 below):
1. When the separation nozzle sucks up the paper, the presser foot starts to press down.
(Figure 1.5)
2. Separation nozzles deliver the sucked paper to the delivery nozzles. This part of the movement can be divided into three stages: a. After the paper suction nozzle picks up the paper, the paper suction nozzle starts to suck the paper; b. The paper suction nozzle and the paper suction nozzle hold the paper together for a period of time; c. Paper separation The suction nozzle puts the paper, and the paper suction nozzle moves the paper forward.
3. The paper delivery nozzle delivers the passed paper to the paper pick-up roller. After the pressure roller on the paper pick-up roller presses the paper, the two hold the paper for a period of time, and the paper pick-up nozzle puts the paper.
4. When the separation nozzle sucks the second sheet of paper, the presser foot should leave the stack of paper in advance.
The other components on the Feida are in continuous working state. The components on the Feida cooperate with each other in this relationship to ensure that the paper is forwarded in an unsteady manner. Let's take a look at the correct working status of each component:
Carefully observe the components on Feida, you will find that almost all the adjustment elements appear in pairs, symmetrically distributed around the presser foot, so these components must work in symmetry, that is, they must comply with the principle of symmetry. The principle of symmetry includes position symmetry, force symmetry and adjustment symmetry.
Position symmetry refers to the corresponding two components in front, back, left and right, high and low three-dimensional space in the vertical plane space symmetry where the presser foot is located. Force symmetry means that the corresponding two parts have the same force. That is, the distribution of inspiratory size, insufflation size, and air volume should be symmetrical. Adjusting symmetry means that when adjusting a component during the adjustment process, it is also necessary to consider whether the symmetrical component needs to be adjusted, and adjustment should be performed symmetrically.
The principle of symmetry is one of the prerequisites for Feida to be in a correct working state. [next]
1.1.5 The adjustment of each part of Feida
There are two points that need to be paid attention to in the adjustment of each component on Feida: a. The formation conditions of the pressure difference; b. Guarantee the free state of the paper. The following detailed analysis of their adjustment methods.
1. Paper suction nozzle. The adjustment principle of the paper separation nozzle is: a. Only one piece of paper can be sucked at a time, not two pieces of paper, so that double or multiple faults are eliminated on the paper feeding table; b. The nozzle should suck Within the rear edge of the paper, it cannot be in a crossing state with the paper; c. For different papers, the angle of the front, back, left and right of the nozzle can be adjusted (any angle in the plane).
?
(Figure 1.6)
The delivery nozzle is the same as the separation nozzle, it can only suck one piece of paper, not two pieces of paper.
2. Presser foot. The adjustment principle of the presser foot is to press the back edge of the paper and cannot cross the paper; the second is to evenly blow into the gap of the paper (between the upper and lower paper), the air volume should not be too large, too easy The front opening of the paper is not flat, and it is difficult to form a small pressure difference, so it must be adjusted until it can form an air cushion between the upper and lower papers, as shown in Figure 1.7.
3. Rear mouthpiece. The adjustment principle of the rear blow nozzle is:
(1). Its position can not be higher than the top paper, otherwise it will destroy the formation condition of pressure difference.
(2). The position cannot be too low. If it is too low, the gas is difficult to get in because of the heavy weight of the paper itself, which is also unfavorable for the pressure difference.
(3). The upper part of the mouthpiece should be slightly lower than the rear edge of the paper, and only blow a few pieces of paper above.
(Figure 1.7)
(4). The blowing volume should be strictly controlled. If the amount of air blowing is too large, the trailing edge of the paper may be blown up, which results in difficulty in pressing down the presser foot. Another reason is that the wind of the mouthpiece may blow at the most when the paper stack has not automatically risen due to the continuous reduction of paper On the paper above, the conditions for forming the pressure difference are destroyed. The adjustment of the air volume is based on the principle that the grading nozzle can suck up the paper, that is, there is a condition for forming a pressure difference at the rear edge, and the blowing of the middle and front of the paper is mainly the blowing of the presser foot. It is sufficient if the mouthpiece can blow loose paper between 5cm from the back edge.
4. Side blowing mouth. The adjustment principle of the side nozzle is basically similar to that of the rear nozzle.
5. Tablet or brush. The adjustment principle of tablet or brush:
(1). The position cannot be too much into the paper, otherwise it will cause great difficulty to the paper separation nozzle.
(2). The position cannot be too far out. Due to the cutting error of the paper itself or the technology of paper breakage, the back edge of the paper stack may be uneven. If the position of the tablet is too far, some paper can be pressed, and some paper may not be pressed.
(3). The position should not be too low. If it is too low, the rear edge of the paper will be held down, and the rear nozzle will be difficult to blow.
(4). The position should not be too high, too high to play the role of separating paper and preventing double sheets.
(5). During adjustment, only the intermediate state of the above four points can be taken. Thick paper has less pressure, and thin paper has more pressure; the back of the paper is neat and less pressure, and unevenness and more pressure.
6. Press block. The adjustment principle of the pressing block: â‘ Close to the two corners, because it is mainly used to prevent the two corners from leaving the original position, and the paper can be evenly raised. â‘¡ The weight of the block is appropriate. It can not be too light, too light can not play the role of pressing paper; too heavy may press the paper too tight, destroying the formation conditions of the pressure difference, and can be replaced according to the specific circumstances.
1.1.6 The best fit between paper, presser foot and separation nozzle
The cooperation between the paper, the presser foot and the separation nozzle has an important influence on the separation of the paper, and many paper feeding faults are related to this, so adjusting them is of great significance to improve work efficiency.
(Figure 1.8)
First look at the paper. It can be seen from the foregoing analysis that the paper is separated and driven forward by the pressure difference. Therefore, the paper itself must create conditions for the formation of the pressure difference, that is, the paper must be in a free state. Let's take a look at the cooperation between the presser foot and the separator nozzle. The previous part described their respective functions and adjustment principles: the presser foot and the paper separation nozzle cannot cross the paper. So how far are they in the paper? Consider from the two aspects of paper cutting error and paper breaking technology. Under normal circumstances, no crossover is allowed, that is, for each piece of paper, the presser foot and the separation nozzle cannot be pressed against the outer edge of the paper, so the presser foot and the separation nozzle are as close as possible to the paper. inside. However, because the presser foot is pressed down after the paper suction nozzle picks up the paper, it cannot be pressed too much in the paper, otherwise it will hit the rear edge of the first paper. Therefore, the best cooperation between the separation nozzle, the presser foot and the paper is:
â‘ The paper is in a free state;
â‘¡The separation nozzle can only pick up one piece of paper, not two pieces of paper;
â‘¢Adjust the angle of the separation nozzle, so that the paper between the two nozzles is always in a tight state, which is convenient for the presser foot to press down;
â‘£ Press the foot as much as possible without interfering with the rear edge of the paper (note the effect on the work of the nozzle).
1.1.7 The best fit between paper, paper suction nozzle, pick-up roller and pressure roller
The cooperation between these four has an important impact on the forward conveyance of paper. First, let's look at the relationship between the next paper suction nozzle and the paper receiving roller.
The paper delivery nozzle delivers the paper to the pick-up roller. There are two questions that must be discussed here: after the paper passes the pick-up roller, is the pressure roller pressed down? Still not passing the pick-up roller, the press roller is pressed down? If the paper does not pass the pickup roller, the platen roller will press down. Because there are only two paper suction nozzles, that is, at most two points of contact. Because the paper is more flexible and easy to bend, it is difficult to keep the front opening in a plane, so that when the paper enters between the pickup roller and the pressure roller, the gap between the paper and the pressure roller and the pickup roller may be In a cross state, the paper cannot enter. Furthermore, due to paper cutting and paper-breaking errors and feeder non-ideal symmetry errors, the axis of the front opening of the paper and the axis of the pickup roller may not be parallel, so that the left and right of the paper entering the pickup roller are inconsistent. Skew. Through these analyses, it can be seen that the paper can only be pressed down after passing the paper receiving roller. So how much has passed before it can be pushed down? There are also several stoppers on the upper part of the pick-up roller. Their function is to prevent the front opening of the paper from warping too much. If the paper passes too much before the platen roller presses down, it may cause the paper to bump against the stopper, causing the paper to rebound (especially the first sheet of paper each time it starts). Another is that after the paper enters the paperboard, it should be parallel to the surface of the paperboard. If the platen roller is pressed down after a long time, it is possible that before the paper was warped, the conveyance of the previous sheet was affected. It can be seen from the above analysis that the paper must pass the paper receiving roller before the paper pressing roller can be pressed down. But it can't pass too much. Ideally, the paper should be pressed against the paper when it reaches the contact point between the receiving roller and the pressing roller. However, considering the cutting, paper-breaking errors and the asymmetry of the paper suction nozzle, the front opening of the paper cannot be completely parallel to the axis of the pickup roller, so all the front openings of the paper must be able to cross the contact point. The value is about 5mm. This distance also creates conditions for the front opening of the paper to recover from bending.
The paper is sent to the paper receiving roller by the paper suction nozzle. The paper suction nozzle sucks the front of the paper, and the position of the paper tail is mainly determined by the height of the paper stack (that is, the height of the presser foot). In this way, due to the different height positions of the paper stack, the relative crossing state between the paper and the pickup roller is also different. If the front opening of the paper is completely flush, and the paper enters the paper receiving roller in three states: forward horizontal, downward sloping, or upward warping, the front and rear positions of the paper on the cardboard are different. When it is inclined downward or warped too much, it may cause the paper to arrive early or late. Therefore, the height of the feeder directly affects the state of the paper entering the pickup roller, which is why the height of the feeder should be adjusted frequently.
Therefore, the best cooperation between the paper, the paper suction nozzle, the height of the paper stack (that is, the height of the presser foot) and the paper receiving roller is:
â‘ The paper is in a free state;
â‘¡Adjust the height of the presser foot so that the paper level enters the receiving roller;
â‘¢ Adjust the movement relationship between the paper pressure roller and the paper suction nozzle to make the paper pass the paper receiving roller by about 5mm, and the paper pressure roller presses down.
this machine is a perfect and ideal one for making flat paper handles, which can do the job from making Flat Paper Rope, doing the embossing on the rope, putting hot glue on the rope and paper strap, folding the handle rope in right angle, forming the Flat Handle, cutting the handle into requested size to putting the cold glue on the ready made Paper Handle at one time. This machine can be connected with production line at the end of the machine to form a complete production unit.
Flat Paper Rope Handle Machine, Flat Paper Rope, Flat Paper Handle, Flat Paper Rope Making Machine
DongGuan FeiYang Packaging Machinery Equipment Co., Ltd , https://www.feiyang-machinery.com