Analysis of the reasons for the inaccuracy of the Electronic counting machine
The accuracy of photoelectric counting machine is an important index of drug packaging quality, which is directly related to the interests of drug users and the market reputation of drug enterprises. In order to analyze the reason why the number of grains is not accurate, the working principle of the number of grains machine should be introduced first. The working principle of the granulator is: the materials to be packed (tablets, capsules, pills) are put into the hopper - the materials to be counted are separated step by step through the three-level (or two-level) electromagnetic vibration plate, so that the materials are arranged orderly - the materials enter the detection counter (each channel is a group of counters) - each channel has several groups of infrared emission circuits and receiving circuits, when the materials are free When the falling body enters the detection and counting channel, the infrared ray is blocked and can not be received by the receiving circuit, resulting in a counting pulse, and the material is counted once - the counted material passes through the memory baffle under the channel and enters the packaging bottle through the falling particle shield. When the counting quantity reaches the preset quantity (total product quantity), the memory baffle under the channel closes to complete a bottle counting.
1. Analysis of the causes affecting the accuracy of counting:
1. Human factors: ① the operator did not preheat the machine before starting the machine according to the requirements of the operating procedures; ② the operator did not supplement the materials in the bin in time during the operation of the machine, which directly affected the separation state of the materials on the oscillating plate, and ultimately led to inaccurate product counting.
2. Machine factors:
(1) The change of gravity is not considered in the bin design, which will affect the fluidity of materials in the oscillating plate and the order of materials. Because the more materials, the higher the center of gravity of materials will increase the fluidity of materials, resulting in the overlapping materials entering the detection channel before they can be separated, resulting in the inaccuracy of the number of particles. With the decrease of the material's center of gravity, the fluidity of the material will be reduced, which may lead to the slow speed of the number of particles.
(2) The drop between the memory baffle and the falling shield is too large, the falling time of the material is too long, the material rotates in the falling shield and cannot fall into the packaging bottle in time, resulting in the inaccurate number of particles.
(3) since the pelletizing shield of the granulator is made of plexiglass, static electricity is generated by high-speed rotating friction when the material falls freely from the detection channel. Another reason is that some components of traditional Chinese medicine are prone to generate static electricity in the process of friction. Due to static electricity, the material is adsorbed on the falling shield, which reduces the effective number of particles falling into the bottle, resulting in inaccurate number of particles.
(4) if the memory baffle is not pushed out in place, all materials cannot be blocked. When the memory baffle is opened, there are still materials passing through the memory baffle, resulting in several inaccuracies.
(5) if the position of the dropping shield is not right, the bottle mouth cannot be blocked completely, so that the materials cannot all fall into the packaging bottle smoothly, resulting in the inaccurate number of particles.
(6) during the installation and adjustment of the machine, the level of the oscillating plate shall be adjusted forward, so that when the oscillating plate stops vibrating, the material will naturally slide into the detection channel and cause a false count.
3. Material factors:
① The setting oscillation frequency of the three-stage oscillation plate for the production of capsules, tablets and pills is completely different.
② In the production of tablets and capsules, due to the large amount of dust in the materials, the infrared ray is blocked by the accumulation of dust in the detection channel, so that the counting circuit can not work normally.
4. Media factor:
① The influence of environmental factors on counting accuracy mainly comes from the quality of compressed air. Compressed air with large water content has a great influence on the sensitivity of actuator cylinder. Once the sensitivity of cylinder decreases, the accuracy of counting cannot be guaranteed.
5. Parameter setting factors:
① The setting size of the bin gate has a great influence on the separation state of the material on the oscillating plate. If the gate is too large, the material flows out too fast, and the material flows out too fast, there will be overlapping phenomenon. When the overlapped material passes through the detection channel, it will affect the accuracy of counting, and if it is too small, it will affect the counting speed. ② Setting of the oscillation frequency of the three-stage oscillating plate. Setting too fast material can not be separated effectively has an impact on the accuracy of counting, too slow and affects the production speed.
③ Setting of product length and minimum parameters. The appearance of the product is directly related to the brightness time and blackout time of the infrared ray of the detection channel. Lighting time is the time between particles. The shorter the lighting time is, the higher the resolution is. The shading time is determined by the appearance size of the product. If the shading time is set too long, there will be fewer counts. If the shading time is set too short, the counter will not be able to distinguish clearly and the elimination will affect the counting speed.
④ Set the value of precount. The precount is to make the machine continue to count the bottles to increase the production capacity after the completion of the dropping guard. When the last drug is detected, all the drug particles will fall into the detection track, and the memory tablet will block them. When the empty bottle reaches the dropping shield, the pre counted drug particles will fall into the bottle. The parameter setting of the expected number is too small to affect the counting speed, and too large to affect the accuracy of the counting.
⑤ Setting of counting speed. If the parameter is set too small, the product can be separated sufficiently on the oscillating plate, which is beneficial to improve the accuracy of counting. But it is not conducive to improving the production speed. If the setting is too large, the product will not separate well on the oscillating plate, which will seriously affect the accuracy of counting.
⑥ Setting of separation speed. Separation speed refers to the separation speed between the last product in the previous bottle and the first product in the next bottle. If the separation speed is too fast, the memory baffle will not be able to separate the products between the previous bottle and the next bottle, resulting in the phenomenon of one more or one less bottle. If the separation speed is too slow, the production speed will be affected
6. Cylinder sensitivity reduction factor: as the executive component of the pelletizer, the speed of reaction directly affects the accuracy of counting. The main reasons for the decrease of cylinder sensitivity are: moisture content in the compressed air, non cylinder specific grease, impurities entering the cylinder, wear and air leakage of the cylinder seal, etc.
(II) methods to improve the accuracy of counting:
1. Human factors: ⑴ preheat for 3 to 10 minutes to keep electronic components and photoelectric scanning circuit in a stable working state. (2) the operator shall pay attention to the materials in the silo in real time and replenish the materials in time.
2. Factors of the machine: ⑴ in view of the problems existing in the material gravity of the lower bin of the granulator: it can be considered to divide the bin into constant weight bin and non constant weight bin, so as to effectively solve the impact of material gravity on the material separation state in the oscillating plate. (2) for the problem that the falling time of materials from the memory baffle to the bottle is too long: it should be considered to add another level of memory baffle to solve the following problems: first, the falling time of materials from the memory baffle to the bottle can be divided into two parts, the charging time of the bottle is shortened, and the first memory baffle is closed when the bottle is charging, and the counter continues to work. In this way, two actions can be completed - the blanking and bottling of the previous bottle and the counting of the next bottle, and the production speed can be improved. Secondly, it can solve the problem of electrostatic adsorption materials.
(3) methods to prevent static electricity: 1. Non-polar materials can be attached to the inner wall of the falling particle shield to avoid electron transfer; 2. Grounding power line and equipment connection can be added to the falling particle shield to effectively release static electricity, so as to prevent static electricity. (4) adjust the position of the memory baffle and the dropping shield, so that the memory baffle can completely block the materials, and the dropping shield can ensure that the particles can enter the packaging bottle smoothly. (5) during the installation and adjustment of the machine, the level of the oscillating plate is adjusted and tilted back, so that when the oscillating plate stops vibrating, the material can not slide naturally into the detection channel, resulting in false counting.
3. Material factor: ⑴ set proper oscillation frequency for capsule, tablet and pill. (2) periodically use a vacuum cleaner to remove the dust from tablets and capsules.
4. Medium factor: ⑴ change the compressed air filter regularly to ensure the air quality.
5. Parameter setting: for the setting of silo gate size, three-stage oscillating board oscillation frequency, product length and minimum parameters, expected value, counting speed and separation speed, the operator is required to repeatedly debug to make it reach the best state, which not only ensures the counting speed, but also ensures the accuracy of counting.
6. Methods to improve the sensitivity of cylinder: strictly control the water content of compressed air, especially the operation of air dryer. Strictly control the non cylinder special grease entering the actuator. When repairing and replacing the actuator, it is necessary to replace the original cylinder. If possible, it is better to replace the actuator of all channels once to ensure the consistency of the sensitivity of the actuator. Reasonable adjustment of machine parameters: prepare counting and counting speed to obtain the best separation effect of products, so as to improve the production speed and counting accuracy. Setting of separation speed; try to set the separation speed close to or the same as the counting speed. According to experience, the separation speed should be 5-10% lower than the counting speed.