On the first day, we all came to the metalworking practice base early, waiting for the teacher's arrangement. Before the start, the teacher moved out a big TV set and played a video for about an hour. Originally, it was to introduce some key points of metalworking practice, including some introduction of equipment and safety guide. The teacher has repeatedly stressed: safety first! This sentence is engraved in everyone's heart, so we always put safety first in our metalworking practice for a week, strictly abide by the rules, never fight in the workshop, be careful and dare not be careless.

In the practice of locksmith, we know that the main contents of locksmith are scraping, drilling, tapping, sawing, filing and scratching. What should be paid attention to in safety, how to use files, saws and other workpieces, techniques, distance, strength and so on. I gradually got to know the fitter. The fitter mainly relies on manual operation and uses various tools to complete the processing, assembly and repair of parts. Compared with machining, it has high labor intensity and low production efficiency, but it can complete the work that machining is inconvenient or difficult to complete, and the equipment is simple, so it is still an indispensable and important type of work in mechanical manufacturing and repair. After listening to the teacher's explanation and watching the pictures, we began to work. Make a square iron block into a certain shape model. The first thing is to measure the size of the iron block and draw lines and lines. This work should not be underestimated. If something goes wrong, it will make your parts oversized. The next step is sawing, which I will never forget. I thought sawing saw meant dragging it back and forth. No big deal. This is a piece of cake. But in fact, sawing is also a trick. Sawing doesn't always make you numb. First, we should adjust the direction of the incision. According to the direction of the kerf, we should lean against the saw blade with our left thumb to prevent the saw blade from sliding sideways. Push the handle smoothly with our right hand. The saw blade should be inclined to the workpiece at a sawing angle of about 10 degree to 15 degree. At the same time, when sawing, the right hand holds the saw handle and the left hand gently holds the front end of the bow. The saw bow should reciprocate in a straight line and cannot swing. The pressure is even when moving forward, and the saw blade gently slides over the workpiece when moving backward. The reciprocating speed should not be too fast, and the pressure and speed should be reduced before and after sawing to avoid arm injury and broken saw blade. You can also add a small amount of engine oil. After sawing, you need to file it. Filing is also a tiring and bitter thing, but it is not difficult as long as you master the method.

First of all, we must get the right gear. It is the key to keep the file moving in a straight line when filing the plane. There are two kinds of filing force: horizontal thrust and vertical pressure. When the file is pushed forward, the front hand pressure gradually decreases, and then the back hand pressure decreases. When the file is pushed to the middle position, the pressure on both hands is the same. When the file is pushed forward, the pressure of the front hand gradually decreases and then increases, and no pressure is applied when the file returns, so that we can file more simply and laborsaving.

(2) Machining

After two days of locksmith work, I got a certain understanding of metalworking practice, so I immediately started machining. Generally speaking, machining requires us to be very serious and cautious, and we can't be careless. The tools used in machining are turning tools, boring tools, drill bits, reamers, knurling knives and forming knives. In the process of machining, the rotary motion of the workpiece is the main motion, and the transverse or longitudinal motion of the tool relative to the workpiece is the feed motion. Lathe is the most commonly used type of work in machining, and turning plays a very important role in mass production, single piece and small batch production and mechanical maintenance. Our practice tool is to process screws and the like. Among them, the biggest difficulty is accuracy. The error is required to be 0.0 1 mm, and the most important thing is that the length should be very accurate. If you accidentally process too much without leaving any allowance, you will have to start over. When processing, we should control the speed. Finally, when finishing, the manual feed should be slow and uniform, and the cutting speed should be low.

Machining is to install the tool first. When installing tools, you should pay attention to:

1) Align the tip of the tool with the center of the tailstock, and ensure that the tip is as high as the axle. The spindle should be perpendicular to the working axis.

2) The protruding length of the cutter head is less than twice the thickness of the cutter to prevent vibration during turning.

3) The cutter shall be well padded, aligned and clamped.

4) After the workpiece and tool are installed, check whether the machining limit position interferes or collides.

5) When removing the cutter for cutting, remember to lock the square tool holder first. After the cutter is installed and aligned, the turning process is started.

When turning the end face, check whether the lathe tool, square tool rest and tool rest are locked on the lathe bed, and adjust the back cutting amount with a small slide plate to avoid the convex and concave end face. Because the diameter on the end face decreases gradually from the outside to the center, the cutting speed also decreases gradually, and the roughness value is larger. So it's best to cut outward from the center.

Finally, the workpiece is cut off. In general, the following points should be paid attention to when cutting workpieces:

1) The workpiece is generally clamped on the chuck, and the cutting place is as close as possible to the chuck.

2) When installing, the tool tip is the same height as the axis of the workpiece, and there is no boss left at the cutting place. The length of the cutter extending out of the tool holder should be as short as possible.

3) Minimize the gap between the moving parts of the skateboard, improve the rigidity of the tool rest and reduce the deformation and vibration of the workpiece.

4) Manual feed should be slow and even, and the cutting speed should be low.

(3) Hot working

Today is the third day, and we are no longer in contact with the metalworking practice base of our school. At about eight o'clock in the morning, we took the school bus to the machining factory of the mansion. I really went to the factory for actual combat this time. On the way, we saw a big and tired slogan hanging in front of a factory: entering the factory means giving up all freedom. Everyone laughed when they saw it. Perhaps this slogan is shocking, but it does emphasize that we should abide by the rules and operate safely.

When I walked into the factory, I saw many large and small mechanical equipment that I had never seen before. The teacher patiently explained to us one by one, but because of the limited time, I only showed us some machines. Then we studied electric welding, gas welding and cutting respectively. Talk about the importance of hot working in modern industry and its inestimable core position, what are the advantages and disadvantages of electric welding and gas welding, and what are the similarities and differences. The teacher patiently explained and we listened carefully, which made the whole practice process smooth. In just a few hours, we learned some basic knowledge of hot work, and initially learned how to operate it, which gave us a more specific understanding of our major and made us love our major more.

Concluding remarks

Time flies, and a week has ended with the roar of various machines. I feel reluctant to leave because the time is too short, which is the only regret of this internship. I really hope the school can give us more internship time. Although a little tired, we are in pain and happy. Because we learned a lot of useful things. As the saying goes, practice is the only criterion for testing truth. Through a week's metalworking practice, I learned a lot of common sense and got mental exercise, which was both bitter and enjoyable. This is another precious wealth in my college life, which is bound to have a great impact on my future study and work.

Soon we will leave the campus, enter the society and face employment. I don't think employers will instruct us how to do it in detail like teachers, but we need to observe and learn by ourselves. Without this ability, it is difficult to be competent for future challenges. With the rapid development of science and the wide application of new technologies, there will be many fields that we have never touched. Only by daring to try can we make a breakthrough and make innovations. Just like mechanical processing and thermal processing, which we are exposed to, although dangerous, we need every student to operate and make finished products, so as to exercise everyone's courage to try. A week's metalworking practice brings us not only the operational skills that we have been exposed to, but also the ability that needs to be exercised through several types of work. More importantly, we need each of us to feel and think according to our own situation after the internship, which is the fundamental purpose of this internship.