When I set foot on Lego, my feeling was this:
Lego is so painful to step on, and "I wish you step on Lego" has even become a terrible curse. Why do small plastic toy blocks have such great lethality?
"I hope you step on Lego barefoot in the dark."
A universally applicable interpretation
Of course, we can find many universally applicable explanations for this kind of pain.
The soles of your feet are very sensitive
First of all, like fingers, the soles of the feet are sensitive to touch and pain, which is very helpful for us to perceive danger. If the feet don't feel pain, the situation will be worse: some diabetics will be very insensitive to the pain on their feet because of neuropathy. They are easily injured and infected, but they can't find it in time. Sometimes the disease even develops to the point where amputation is necessary.
Are you fat? Actually not.
You put your weight (even the extra force of pedaling while walking) on a small piece of Lego bricks under your feet, and the resulting pressure must be fatal. Regardless of the bulge, the surface area of a 2*2 Lego block is about 2.5 square centimeters, and a person weighing 60 kilograms can generate 2352 kPa of pressure.
Of course, appearance is also very important. If projections and sharp corners are included, the damage value will be higher.
What is so special about Lego? Extremely difficult
Of course, the above explanation applies to all small objects that may have close contact with the soles of the feet. So, why do people always complain more about their tragic experience of stepping on Lego? Is there anything special about Lego bricks compared with other little things? There really is.
Of course, Lego toys are more likely to haunt the floor, which is definitely a factor. However, what is said here is the characteristics of Lego bricks themselves. Simply put, compared with many other objects that may be trampled on in daily life, Lego bricks are outstanding in firmness. It is very hard, even if you step on it, those solid structures and sharp edges and corners will not deform, and will still directly hit your soles.
Seeing this photo makes me nervous. ...
At first glance, Lego bricks seem to be just ordinary plastic blocks, but these plastic parts can have great accuracy: they can fit each other accurately, neither too tight nor too loose. It is said that the dimensional error of these small bricks can be as low as 0.002 mm, but if you want to make plastic small parts have such accurate dimensions, production technology and what kind of materials to choose, you will have great knowledge.
The process of making Lego bricks is actually very simple. Just use a kind of processing equipment called "injection molding machine" to heat and melt the plastic into a flowable melt, and then quickly inject it into the metal mold. After cooling, you can get a Lego block.
A retired Lego injection mold.
So, what materials are used for Lego bricks? Since 1963, Lego has used a plastic called "ABS" instead of the original version of the material (cellulose acetate) to make these mosaic toys. ABS is one of the five most commonly used general plastics in the world, and its chemical name is acrylonitrile-butadiene-styrene * * * polymer, which is polymerized by acrylonitrile, 1, 3- butadiene and styrene (at present, some ABS are * * * polymers). * * * Polymerization is a common method to manufacture polymer materials. Its advantage is that different monomers can be selected for * * * polymerization according to different performance requirements of materials, so as to obtain materials that are more in line with people's needs.
ABS plastic particles, and three kinds of monomer molecules used to produce it.
Why ABS? This is because the material characteristics of ABS can meet all the requirements for making Lego bricks. ABS is an excellent partner of injection molding process, in which the styrene structure can bring low viscosity to the material when it is heated and melted, providing sufficient fluidity for injection molding production; The existence of butadiene structure will bring good toughness and impact resistance to the material, especially at low temperature, the plastic will not become brittle; However, strong hydrogen bonds will be formed between acrylonitrile molecules, which will provide rigidity and hardness for the material and make the material more corrosion-resistant. In addition, the existence of * * Poly structure makes it difficult for ABS material to crystallize, and it will not shrink too much when cooled in the mold, so the dimensional stability is also good, and the manufactured small parts can maintain a high degree of consistency, which is particularly important for embedded toys.
Knowing the essence of ABS, it is not difficult to understand the pain it brings. Pain comes from local pressure, and there are only two factors that cause great pressure: one is sharp and the other is hard. In the process of injection molding, ABS with good dimensional stability inherits the clear edges and corners of Lego mold, so its edge is naturally "sharp" The surface hardness of ABS is very high, which can reach the Shore hardness of 100 degree (the highest level measured by this method). Ultra-hard ABS can even be regarded as the hardest kind of plastic. Not only that, but the strength of these plastic building blocks is also amazing. People have specially done experiments and found that 2x2 ordinary Lego bricks can bear an average force of 4,240 Newton before being crushed, which is equivalent to a weight of 432 kilograms.
Lego bricks that finally collapsed under the pressure of more than 4,000 Newton-Aha, you have today!
In theory, if such small bricks are stacked one by one until the bottom brick is crushed, a 3.5-kilometer-high "tower" can be built. Of course, this kind of structure is actually very unstable, but if each floor is reinforced with more bricks, it is no problem to build a music tower of more than 30 meters. By contrast, a person's weight is really nothing. Even if you stand up on your own, those angular and hard structures will not collapse at all.
At present, the tallest Lego tower in the world is 35.05 meters high, and about 550,000 Lego bricks are used.
Generally speaking, the pain of stepping on Lego bricks is probably a little accident between human sensitive nerves and polymer materials with excellent performance. This experience is definitely unpleasant, but we can also get good news from it: your beloved Lego bricks are very strong, so you don't have to worry about stepping on them at all. ...