Talking about fruit packaging from the internal injuries of apple

Not long ago, Chen, the owner of the fruit, received a return. I saw the end of the appearance of the apple, cut open the skin but exposed a dark brown piece of spotted, until the bad area all cut away, looks very large apple will be left. The strange thing is that these apples, which are already broken, do not have any trace of appearance. In the face of these returns, boss Chen immediately checked the stock of apples. It was found that most apples in the warehouse had this kind of problem. Faced with this situation, Chen boss is really anxious. What are the reasons for the problem?

It is not difficult for a person who understands mechanics to answer this question. The fault is in transportation. People always want to pack more in order to reduce the amount of packaging used to increase the efficiency of unit packaging. They do not know how much the equipment is installed, causing the carton to protrude. In the process of stacking, the apples at the bottom of the carton can be poured and crushed. And when the vehicle rides over bumpy roads, the pressure on the vibrations increases the pressure on the apples in the carton.

However, how can this explain the apparently good and internal injuries of Apple? This problem is very clear in Mr. Wu Jike's article in "talk about contact issues." Apple's "internal injury" problem is just a typical contact problem. It is assumed that the apples in contact with each other are two elastic balls with radius R, and the pressure between the two balls is P. At this point of contact, the deformation of the ball is no longer a point, but a circle with a radius of a. According to the theoretical analysis of the contact problem, it can be concluded that the maximum shear stress in the sphere.

The maximum shear stress does not occur on the surface but in the deep layer, and the larger the radius and pressure, the greater the depth. Although the shapes of the actual contact objects are various, the above basic laws are common, which is why Apple's appearance is good and internal injuries are numerous. As long as the height exceeds a certain level, there is always a large layer of apples that can not escape this fate. The apples that are thrown away each year are counted in thousands of tons. Therefore, improving the packaging and transportation conditions is the fundamental way to save the apples.

How can we effectively prevent these apples from being destroyed?

First of all, we need to reduce the stacking height of apples. In other words, the height of the carton should be reduced. Facts have proved that reducing the height of cartons is the most important measure to reduce the damage to apples. The purpose of reducing the height of the fruit carton is to minimize the compression of the apple under the gravity of other apples. This squeeze is the main cause of apple damage. Judging from the inspection of the apples stored in Chen’s boss’s warehouse, the apples on the bottom of the box have been subjected to strong squeezing even though the apples are superficially intact. This point shows the problem.

Second, there is a need to reduce the number of apples in each carton. In principle, the support capacity of the upper cartons should be provided entirely by the lower cartons, and the fruits should not be subjected to even a little support pressure. Since the apples in the warehouse of Mr. Chen’s boss are packed full of boxes, the lids of the apples are protruding, causing the upper layer of apples to directly press the lower layer of apples. The power of the upper apple is entirely borne by the lower apple. After stacking up to 12 storeys (warehouse stacking), a considerable part of the apple was under tremendous pressure. This is the direct cause of the apple's crushing. The third is to reduce energy absorption and destruction during transportation. Since the UP foamed material is wrapped between apples, the buffering performance is relatively good, but the ability to absorb vibration is insufficient. This makes the energy in the shaking process turn into the destructive power of apple. Ever since, after a long period of transportation, Apple has been severely damaged.

A better method is to choose a cushioning material that absorbs strong vibrational energy so as to prevent the shear stress from being destroyed.

Of course, this kind of thing will happen not only to apples but also to other kinds of fruit. Industries that are not rigid materials, such as various plastic products. The solution is nothing more than following the above analysis, of course, this idea can be used in eight words: "low box, low loading, shock and buffering" to summarize. In general, as long as the eight-character principle is satisfied, this problem of causing damage within the article will not arise.