BÙI HỮU HẢI by Hải Bùi

writing

hai075289 — 2023-09-17 12:56:06 UTC

Now I will give you some advice to make an effective presentation. Firstly, the basic structure of a presentation. It consists of at least 3 parts, they are introduction, body, and conclusion. In the introduction, you need to greet the audience, express the purpose, give the structure and time, and hand questions. At the body, you must develop your presentation of each problem. With each problem, you need to introduce the problem, give example, then summarize it before moving on to the next problem. In conclusion, you should summarize the whole presentation, closing and ask your audience for getting some questions. The second piece of advice is about what should you do before and during the presentation. Before the presentation, you need to prepare yourself carefully. For example, you should dress formally, and turn off your cell phone. In the presentation, your gesture is very important, you should smile a lot, be confident and give eye contact with your audience. So what about what shouldn't do during and after the presentation? You shouldn't put your hand in your pocket, not look at the papers, ceiling, or floor. Are These all my advice for you, if you can do all of them well, I believe that you will make an effective presentation.

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hai075289 — 2023-09-17 13:15:39 UTC

writing

hai075289 — 2023-09-22 16:33:07 UTC

Couplings are most commonly mechanical devices. They are used for transmitting power from the shafts to the others. There are many kinds of couplings, and I know two main kinds. The first type of coupling is rigid coupling. Rigid couplings can make a perfect alignment of the shafts with each other, and they reduce wear on the machine. They also maximize performance and efficiency, but they will be broken if the shafts are misalignment too much. The most common type of rigid coupling is sleeve-style coupling which consists of a cylindrical sleeve. The flexible coupling is the second coupling that I know. The function of a flexible coupling is the same as rigid coupling. Flexible coupling can help reduce noise and unwanted vibrations. But flexible coupling can't make a perfect alignment. If the shafts are slightly misalignment, the flexible coupling is a good choice. Beam coupling is an example of a flexible coupling. It is cut in a spiral shape. Beam coupling can accommodate several degrees of shaft offset.

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hai075289 — 2023-09-22 16:45:11 UTC

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hai075289 — 2023-09-26 12:29:39 UTC

Bearing is one of the most commonly uses in Mechanical Engineering. Bearing is divided in to 2 kinds: rolling contact and journal. Rolling contact bearings are used to support loads. They have 3 main parts: rollers, inner race and outer race. There are 4 main types of rolling contact bearings. Ball bearings use a spherical rollers to support radial and axial motion. Straight roller bearings use cylindrical rollers to support radial motion. Tapered roller bearings use conical rollers to support radial forces moderate thrust forces. Thrust roller bearings use barrel-shaped rollers to support thrust motion. The different kind of bearing is journal bearing that use a lubricated sleeve and has no rolling part.

speaking2

hai075289 — 2023-09-26 12:39:33 UTC

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hai075289 — 2023-09-29 14:57:09 UTC

I know two types of drives. They are flat belt drives and Chains belt drives. Firstly, flat belt drives are the most common type nowadays. We can find them in sawmills, water pumps, or rice mill machines. The pulleys were usually made of wood and it was not until recently that the belts were made of anything but leather. These drives use friction to transmit power so tension is very important in these drives. The second is chains belt drives. Chain drives are most often made of meta. They can slip if they don't have teeth. They are worn down fastly if not properly lubricated. Chains are often narrower than belts, and this can make it easier to shift them to larger or smaller gears. Flat belt drives and chain belts drive have both advantages and disadvantage.

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hai075289 — 2023-09-29 14:57:51 UTC

Gears play such as an important part in machines that they have become the symbol for machinery. Firstly,The simplest type of gear is spur gear. Its teeth may project toward or away from the center beside spur gears are easy to install,cheap,the most common and simplest gears. Spur gears are used for transmitting motion along parallel axes rather than for changing direction. Secondly,Angled helical gears mesh more smoothly than spur gears. Its teeth are cut in a spiral shape and reduce noise and vibration. It is used for transmiting components and reducing speed. Finally, bevel gear is gears meet each other at an angle. It is usually 90 degree and the function of it is to transmit components and transmit power at angle.

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hai075289 — 2023-10-05 02:48:34 UTC

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hai075289 — 2023-10-07 10:28:23 UTC

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hai075289 — 2023-10-10 10:57:17 UTC

Here, we will discuss the two types of drafting services you will encounter in your journey: CAD drafting and manual drafting.Manual drafting is all about producing all these technical drawings by hand using drafting pencil, or drafting pen, drafting paper, a scale ruler and stencils.CAD drafting, on the other hand, uses software that simplifies and speeds up the production of technical drawings because it features drafting sheet templates and automatically duplicates repeating design elements.The advantages of CAD include: the ability to producing very accurate designs; drawings can be created in 2D or 3D and rotated; other computer programmes can be linked to the design software. With manual drafting, you must determine the scale of a view before you start drawing. This scale compares the size of the actual object to the size of the model drawn on paper.In my experience and opinion, rather advantages, CAD drafting does not have any disadvantages to expose except one - the affordability of software.

writting 2

hai075289 — 2023-10-10 10:57:50 UTC

Today I will introduce about Autocad 2018.It’s developed by Autodesk corporation and it was used to build the 2d and 3d model. But I do not recommend 3d design in cad because there are still many limitations. Went through many versions, autocad gradually improved and brought stability as well as many new features to users. Talk a little about why I choose this version and not the 2020-2021 version because the 2018 version is considered a stable version, suitable for even weak computers. Advantages of autocad can be mentioned: the accuracy is much more optimized than when drawing by hand. Detect errors quickly and make corrections right on the drawing. Send drawing files quickly. Besides the advantages, there are still some disadvantages: User training takes a long time and is expensive; Large CAD maintenance and upgrade costs. Until now, autocad supports 3 formats: DWG, DXF and DWF (a format developed by Autodesk)

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hai075289 — 2023-10-12 13:52:07 UTC

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hai075289 — 2023-10-12 14:04:00 UTC

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hai075289 — 2023-10-18 15:30:36 UTC

The check valve is made of cast iron. There are six steps in the process of manufacturing a wheel.

The first step is casting. In this step hot liquid of cast iron is poured into a containner and then cooled to make the correct shape .

In the next step, the material is turned on a lathe toremove excessive parts.

Next, the part is drilled. In this step holes are made on the sheet using a drill.

After drilling, The next process is that the parts are bolted together through bolts. The bolts are tightened so that the materials do not move during use.

The next step is the painting process. After that, the surface of the valve is protected from environmental corrosion. Before completing the product process we need to wait for the paint to dry for a period of time before continuing to the final step.

The final step is inspection, the work is checked carefully to make sure that the part has been made property.We need to check the satisfactory size, surface finish, before packing the product.

speaking1

hai075289 — 2023-10-19 11:17:58 UTC

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hai075289 — 2023-10-19 11:54:29 UTC

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hai075289 — 2023-10-26 11:19:02 UTC

As far as I know, plastic is a synthetic materials that use polymers as a main ingredient. Plastic is able to be moulded or shaped to any forms. Nowadays, many products are made of plastic such as food containers and machine parts. Plastic is versatile, lightweight, durable and some kind of plastic are safe. There are many advantage of plastic. The first benefit is that it’s convenient. For example, we can use shopping plastic bags. Another pro is that it’s lightweight. It can be used in manufacturing airplane interiors and exterior parts. Beside, it’s cheap. It can be formed into final useful from quickly and inexpensively. Moreover, it’s durable and resistant to all kinds of adverse outside factors. For instance, it is quite resistant to heavy rain, storms. Finally, it is reusable. However on the other hand. Plastic has some disadvantages. Firstly, it hurt the enviroment. Secondly, it can’t be biodegrable. Last but not least, it can’t be possible.In the past, we weren’t able to mould plastic into complex shapes. At present, it is possible to replace compoments in engineers with plastic. In the future, we will save money and increase efficiency by using smart plastic coatings on manufacturing components.

writing2

hai075289 — 2023-10-26 11:21:40 UTC

There are 7 types of plastic with different uses and features including: PET, HDPE, PVC, LDPE, PP, PS, and other plastic. Plastic number 1 is PET. PET are the widely recycled plastic in the world. It is mostly used for food and drink packaging purposes due to its oxygen prevention. Plastic number 2 is HDPE. It is relatively hard and resistant to impact and can be subject to temperatures of up to 120C. HDPE used for bags, milk jugs, recycling bins… Number 3 is PVC. It is versatile and lightness. It comes in two basic forms: rigid and flexible ones. In its rigid form, PVC is used in the building and construction. In its flexible form, PVC applied to plumbing, writing, and electrical cable… Plastic number 4 is LDPE. It is flexible, odorless and transparent. LDPE is used in plastic bags, containers, bottles. Next is PP. It is hard and sturdy, PP can withstand high temperatures and is found in car parts, thermal vests, yogurt containers. Plastic number 6 is PS, it is a very expensive. It can be found everywhere: beverage cups, insulation, packing materials… PS is highly inflammable but dangerous as it can leach harmful chemicals. Finally, is other plastic, if plastic cannot be identified in the six types above-mentioned, then it will be included in group number 7. The best-known plastic of this group is PC used to build strong, tough products such as: lenses for sunglasses, sport and safety goggles, and found on mobile phones, compact-discs. Plastic number 7 is almost never recycled.

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hai075289 — 2023-10-30 04:11:38 UTC

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hai075289 — 2023-10-31 03:38:44 UTC

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hai075289 — 2023-11-07 09:24:02 UTC

As you can see in figure 1, This is the process of plastic moulding process. There are seven steps in this process. First, pallets of plastic are fed from the hopper in to a cylinder. Second, the pallets are pushed along the cylinder by a rotating screw and heat. Next, the screw stops rotating and then a ram in front of the screw moves straight forward. Then, the soft, warm plastic is pushed toward a nozzle by the ram. After that the soft plastic is injected through nozzle into a shaped cavity between the two halves of a mould. Next step, the plastic is cooled in the mold, and becomes hard in side the cavity. Finally the mold opens and the cold, hard solid plastic shape is ejected

writting2

hai075289 — 2023-11-07 09:24:38 UTC

From my point of view, there are 3 typical problems of plastic injection moulding. They are short shot, sinkmark and void. As I know, short shot is caused of 2 reasons. Firtsly, there is not enough plastic in the shot. Secondly, the plastic pressure loss in the mould is too high. There are 3 ways to short shot these causes. The first one is that check the shots continuosly and use plastic with high melting capability. Next increase fill speed, plastic and mould temperature. Then increse gate size and runner. Void is caused of 2 reasons. Fristly, it is caused by plastic shrinkage (a hole suddently develop in a thick section during cooling. Secondly, plastic volume changes when plastic is heated or cooled. There are 2 attack to void these causes. Fristly, I think we should reduce wall thickness. Secondly, We had better slow down cooling rate

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hai075289 — 2023-11-07 14:58:42 UTC

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hai075289 — 2023-11-07 15:05:51 UTC

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hai075289 — 2023-11-14 14:51:50 UTC

This is the lathe maintenance schedule. Materials are turned on a machine called a lathe. Part of the materials is removed to make the correct shape. The guideways should be cleaned daily to avoid interruptions and control the line of motion of fluids. You need to inspect the oil level daily to ensure engine efficiency. If the oil level was low, your engine would overheat, leading to expensive repair. You should renew coolant to prevent damage, keep engine at the correct operating temperature, help it warm up quickly in cool weather and not get too when under stress. Renew oil need cleaning weekly to help the machine operate smoothly. If the engine oil changes are neglected, the internal parts of the machine will overheat and work ineffectively

writing2

hai075289 — 2023-11-14 14:52:22 UTC

This is the milling maintenance schedule. Milling machines are among the most versatile. Usually they are used for milling flat surfaces, but they can also be used to machine complex profiled surfaces. Renew oil need cleaning weekly to help the machine operate smoothly. If the engine oil changes are neglected, the internal parts of the machine will overheat and work ineffectively. You need to inspect the oil level daily to ensure engine efficiency. If the oil level was low, your engine would overheat, leading to expensive repair. You had better clean the guideways every day to avoid interruptions and control the line of motion of fluids. The lubricate machinery need to be cleaned every 3-4 months to cut down on friction and heat. You should clean the machine weekly to remove dust and dirt

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hai075289 — 2023-11-14 15:02:42 UTC

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hai075289 — 2023-11-14 15:39:28 UTC