The size grasp in the mechanical design process is actually the embodiment of a person's design ability, if you do not have the corresponding design ability, the so-called size grasp is not good. So today I am here to share with you a set of basic design processes and methods, and only practical methods can open up your path to perfect professional skills.
01 Determine the size of the purchased functional parts in advance
The beginning of any design should be based on the overall requirements of the program, first confirm the model and specifications of some purchased functional components, so that you can not only get the delivery time, cost and design size, but also basically evaluate the feasibility of your plan, and one of the important things for structural design is the design size of the purchased parts.
The so-called purchased functional components, we can have a general understanding from the above figure, of course, there are only many types of far more than that, I just use these to give an example, these purchased functional components can be completely confirmed by the supplier's product samples to confirm the design size, some samples are paper, some electronic samples improve the two-dimensional and three-dimensional drawings of parts (such as Japanese SMC pneumatic components, China AirTAC pneumatic components, Japanese THK products, etc.).
As a design engineer, the first thing to do is to draw the corresponding part structure based on the supplier's sample, and then draw the corresponding part structure according to the model and specification you choose, which is your biggest design foundation, and this thing is basically not wrong and will not be changed (if this needs to be changed, it can only prove that your design plan is wrong, and it has been wrong from the source).
For example, if we draw a complete machining center and a certain feed assembly drawing, we should start from the screw rod and draw outward, first draw the screw rod, then draw the shaft end, then draw the motor seat and bearing, and then draw other related components (of course, the premise is that you have confirmed the general structure, such as the formation, the shape of the machine tool, etc.), many parts are designed to be a ring, one size to another size, are reasonable, never give a size, each size has a source and use.
Therefore, for a mechanical structure design engineer, it is a very important basic skill to have and be familiar with the product samples of the product supporting suppliers, which is also your most important resource and ability, not only the in-depth learning and mastery of technology, but also the accumulation and maintenance of supplier contacts, which is a process of self-awakening and rising.
02 Confirm the design structure
In the processing of mechanical design structure, everyone has their own habits and ways of thinking, which is difficult to unify, but some traditional structural forms must have a full understanding and mastery, such as how many kinds of connection methods there are flanges, how to better deal with these connection methods, and at the same time when designing parts, we should not only consider the functional requirements of the parts, but also consider the processing technology requirements and assembly process requirements of the parts, and even consider the convenience needs of after-sales service, etc., which is a very comprehensive ability.
A few days ago, more friends chatted, said that a university teacher outside to pick up private work, to help others design a set of stamping die, in the mold trial, stamping molding is no problem, but when taking the parts found that can not be removed, it turned out that the mold stroke is not enough, which makes it very embarrassing, this is the structural processing of the wrong place, the so-called structural processing must be based on the comprehensive evaluation and thinking of the function of the product, the product from design, to procurement, to outsourcing processing, to assembly, to commissioning, to production, and then to after-sales need to go through their own minds again, don't be lazy, if you don't do this work, you will find that you will fall in any of the above environments, a product that should be perfect will be disfigured beyond recognition by your final patchwork, or even a complete failure.
Where does the ability to deal with structure come from? from more looking, more drawing, more thinking, from your project design experience, more from the mistakes you have made, and of course, more importantly, from the guidance of a great teacher (a good teacher can make you get twice the result with half the effort, he can click on you casually, you can save months of detour time), but a good teacher is hard to find, because others do not owe you, and more importantly, as a workplace opponent, others want to see your jokes, so this requires luck.
In fact, my suggestion is that if there is no good teacher in reality, then find the drawings to copy, look and think, this is the most realistic shortcut, for a design engineer, imitation is definitely a shortcut to self-growth, don't think about innovation at the beginning, as long as you can get the experience of your predecessors, it is already a great ability.
The confirmation of the design structure here refers to both the overall structure of the product and the structure of the parts that make up the product, which are basically confirmed in the design process of the assembly drawing, which is why there are not many design engineers who can do the scheme, because the comprehensive ability needs to be too high, and it is not something that can be mastered by playing for a few years.
03 Design part drawing (wall thickness)
Confirm the shape of the part, how to confirm the wall thickness of the part, this is a very confusing thing for many people, the confirmation of the wall thickness of the part needs to consider many elements, such as the shape of the part, the material of the part, the molding method of the part, the heat treatment requirements of the part, the strength of the part, the position of the part, etc., only these comprehensive elements are considered completely, in order to really design a qualified part drawing, of course, this is not easy.
The simplest and lazy way is to learn from (to put it bluntly, it is copying), first check whether the company has made similar products before, whether there are similar parts on the product, and then consider the relevant elements mentioned above, combined with the design size of the previous drawings, in order to confirm their own part design, which is a way with the lowest error rate, because the mistake has been basically made for you.
Many people in the industry who take the pure academic route are advised to do mechanical analysis, don't listen to them, most parts do not need and cannot do mechanical analysis, otherwise what awaits you is to be fired, the research and development of enterprises, the speed of marketization, pay attention to speed and cost, if you design a part to do a mechanical analysis, then wait for you to make this product, it is estimated that the daylily is cold, and the boss is going to drink the northwest wind.
When you have a certain design ability, you will slowly form your own design principles, what kind of structure you will give what size, what kind of material you will correspond to what kind of requirements, this is all internalized in the subconscious of the heart, there is no need to think about it, it is a natural thing.
In this matter, try to communicate with people who have experienced a lot of R&D experience, and their abilities are all exchanged for real money, and you can continue to use them by stealing a little bit of learning. And people in science and engineering have a habit of "being a good teacher", as long as you humbly ask for advice, you will usually get a good result, although it is difficult for them to pass on their tricks to you, but some basic design attempts, you can still identify and obtain from the communication with them, this is the workplace you should run the most.
There is an old saying in my hometown: the mouth is sweet, as long as the tongue rolls. In many cases, the use of a diligent mouth is far greater than the use of a diligent hand and foot.
04 Confirm the standard parts
As mentioned earlier, the selection of standard parts is relatively easy, and once you select the standard parts, then you will confirm the structure and size accordingly, in the design process, you must make full use of these parts that can easily confirm the structure and size, the more such parts, the more effective the treatment of your structure.
And when choosing standard parts, its selection variables are relatively few, for example, we can confirm the selected model and specifications from several aspects such as force range, assembly method, standard parts material, standard parts use, etc., and then design the corresponding drawings according to the selected model and specifications, in fact, in the current two-dimensional software and three-dimensional software, there are standard parts library, so many graphics only need to be called directly, basically do not need you to draw, what a cool thing. Of course, to choose a good standard parts, it is not really such a non-technical thing, but it is a little simpler than the design of the parts, if you still have no clue, then my advice is to learn from, to take the road that others have successfully passed, you are at least not easy to fall into the pit, because the pits on the road have been filled with their own bodies by predecessors.
05 Mechanical Analysis
Although we use relatively few places for mechanical analysis in the process of product design of enterprises, we still have to do mechanical analysis in the places where we should do mechanical analysis, which is related to the quality and cost of products.
There are many ways of mechanical analysis, the old traditional way is to check the manual, set formulas, look at the structure and so on to calculate, of course, the latest way is to use three-dimensional design software to do mechanical analysis, you can simply achieve the perfect realm of "more, faster, better, and cheaper".
To sum up, in fact, in the process of design, the most effective training is based on the drawings of the hand-in-hand analysis and explanation, which can not be replaced by any article and method, my habit of training is to let the new people according to my requirements to disassemble the parts drawing, first according to their intentions to draw, and then hand it over to me to check, I will list all the bad places in the design process, and then call him over to tell him how to modify, why to modify it like this, and then let him change the drawings according to my explanation, and then hand them over to me for review after changing the drawings, if there are still problems, I will let him modify again, so repeatedly, after several rounds of product designA newcomer can basically establish his own initial design awareness, and then consolidate his design foundation through a large number of product design projects, and gradually cultivate his own design style and principles, so that he can slowly let go.
To be honest, it is really not easy to train a qualified design engineer, especially to train a person, it is really a very tiring thing, every time I do this I tell myself, this person is a knife, I want to sharpen him, let him become an invincible weapon in the workplace, every time I think about this, I will get some comfort in my heart.