Injection molding is the first department of my internship. When I stepped into the injection molding workshop, I suddenly felt that the industrialization I had imagined was so close. The large injection molding machine keeps spitting out products, and the mechanical arm stretches freely. Transparent or colored templates slowly flow from the conveyor belt into the workshop where products are stacked. These products were later called raw materials. This process is called injection molding, and its principle is to melt the injection raw materials by heating and inject them into the mold cavity, then cool and shape, and finally take out the product. In this process, a good mold plays a very important role. We also see that some products have a hole in the material when they are just punched, so it is necessary to cut them by hand, which wastes both raw materials and manpower. Therefore, a good mold is required when the project is transferred to production. After the preliminary work is done, many resources will be saved in the follow-up, both tangible and intangible. Quality control of incoming materials is also the premise of producing good materials, especially transparent materials and light-colored materials. Black spots on materials are enough to scrap products, so strengthening incoming inspection is responsible for the whole pre-production stage.
The highest defect of our products is spraying. During my internship, I heard that some products have poor spraying as high as 50% or 60%, so I will focus on spraying and summarize my humble opinion.
Now, I will briefly introduce and review the main spraying technology in our factory. The effect of many buttons is expressed by spraying. The principle of spraying is that compressed air is ejected from the center of the air nozzle of the spray gun, and a negative pressure area is formed at the front end of the ink nozzle, so that the paint in the ink container is ejected from the ink nozzle and immediately enters the high-speed compressed air flow, so that the liquid-gas phase spreads rapidly, the ink is atomized, and the ink is scattered and attached to the product surface in the form of paint mist.
Most of the products we usually see are realized by this simple process and have the characteristics of diversified colors. This effect is easier to achieve in different series of products. By mixing the ejected ink, various visual effects can be achieved. In addition, it also has other advantages, such as high spraying efficiency and less restrictions by ink varieties and product conditions.
Our factory has two kinds of spraying machines, which are used for mass production and small batch proofing respectively. One is automatic spraying, which controls the direction of the nozzle through mechanical transmission, and the moving speed is uniform, and the thickness of the sprayed product ink is relatively consistent. The production of batch products mainly depends on it to complete spraying; The other is manual spraying, which requires higher requirements for operators. Only by controlling the speed and distance can we achieve good results, and the product surface area will not be shiny or uneven, resulting in defects. Of course, spraying also has its own shortcomings, such as large ink consumption and low ink utilization rate. Nowadays, the price of ink is rising, and this shortcoming cannot be ignored. We should also see the connection between our success rate and the surface of the product. There are some factors, such as lint and particles, which will lead to the scrapping of the final product. Generally speaking, the utilization rate of ink is low.
How to improve the yield of spraying I think there are the following aspects to pay attention to:
First, the spraying environment, dust-free environment will be the absolute guarantee of high-quality products. In the construction of our workshop, there is a bad idea that sometimes the workshop is used for customers to visit, not for making our products. During the internship, in the spraying workshop, the ink on the work clothes of the machine spraying operator was piece by piece, which was unprofessional.
Second, the cleanliness and smoothness of the product surface will affect the spraying quality. Therefore, it is necessary to clean the surface of the product before spraying. During my internship in our company, I saw that the method of spraying silica gel is manual cleaning, that is, using the viscosity of adhesive tape to stick off the dust on the surface. I think we should find another way to clean it.
Thirdly, the machine itself and the factors of ink quality, the air pressure used by the spray gun have a specified range. When the air pressure is high, the paint mist particles are fine, but the paint mist is more dispersed and the ink loss is large; On the contrary, low air pressure, coarse paint particles and rough product surface will produce defects such as skin, pinholes and bumps. When spraying, the air pressure of the spray gun should be adjusted according to the characteristics of the spray gun and the surface condition of the product. When spraying, the air pressure should be stable to avoid the insufficient supply of compressed air from affecting the surface effect of the product.
By improving the hidden factors of environment, machines and objects, the current situation of poor spraying quality may be changed.
I still feel the status quo of our suppliers. Let's take electroplating for example. There is a small side key for an item. When making samples, the electroplating company did it three times to meet our requirements. In fact, this process is not difficult, that is, ordinary trivalent chromium electroplating, but his first 200 tests can not meet the requirements of customers. Why does such a small side key have such a problem? Is it the lack of communication between us or the carelessness of the supplier? I think there are some problems in our suppliers at present, and we need to make statistics on where these problems are and how to solve and eliminate them well. For example, the color difference of electroplating gun color should be controlled. As long as the conditions and parameters are the same, we are not afraid to make biased products, but often the batches are the same, which is a headache. Therefore, it is suggested to make a technical evaluation of our suppliers or explore new supply channels.
After the internship, I feel that I have injected new knowledge into my head and have a deeper understanding of the company. In the future work, I hope I can use what I know to deal with related problems, explore new problems, and let myself and the company make continuous progress.
165438+1On the morning of October 20th, under the guidance of the instructor and the monitor, we came to Xinfei Plastic Products Factory and started our new day's professional knowledge and practical experiments.
We visited all the production workshops and saw the injection molding machine with the model HTF450-3W. We only saw that the mold was driven by the injection molding machine to move back and forth, and the staff kept taking out the finished products. After the tutor's explanation, I learned that the raw materials enter the inner cylinder of the material from the hopper dryer, which is heated and pressurized to fill the whole cavity of the mold in the form of liquid, and finally cooled and shaped to get the desired product.
Later, after detailed inquiry, I got a general understanding of the working principle of plastic injection mold: before injection molding, the mold was closed and not locked under the action of the clamping device of injection molding machine. During molding, the plastic melt injected from the nozzle of the injection molding machine flows into the cavity through the mold sprue sleeve and parting surface. After pressure maintaining, feeding and cooling, the mold clamping device of the injection molding machine drives the movable mold to retreat to the left, so that the movable mold sprue sleeve and the fixed mold are opened from the parting surface. Plastic mold can be regarded as the following parts with similar functions: molding part, gating system, guiding part, pushing mechanism, side parting core-pulling mechanism, exhaust mechanism, cooling and heating device and supporting and fixing part.
After understanding the working principle and mold structure of injection molding machine, I went to the mold storage area to witness the long-awaited mold. Read the die card in detail, some die structures are one-for-one, some are two-for-one, and the material column is ABS. I learned from the instructor that "one out of one" means to produce only one product at a time, while "one out of two" naturally means to produce two products at a time. ABS refers to propylene glycol-butadiene-styrene polymer, and refers to the material or raw material of the product.
We also visited the grinding workshop and the repair workshop. In particular, there are various machine tools (such as "Hanchuan Machine Tool"), grinders, vertical lifting table milling machines, single-axis CNC EDM machines and WEDM machines in the repair workshop.
In Xinfei, I have a particularly deep feeling: Xinfei pays special attention to energy saving. Everyone knows that energy is an important factor affecting the cost of finished products. Xinfei mainly starts with improving the qualified rate of products, which is not only related to raw materials, injection molding machines and operations, but also depends on the quality of molds to a great extent.
A good mold can not only produce good products with high qualified rate, but also produce high quality products. As far as the plastic parts of Xinfei refrigerator are concerned, the surface smoothness, smoothness and font clarity are closely related to the mold used.
After leaving Xinfei, I went back to school by car, and today's internship is over.
Part VI: Visit the Cologne Company in Henan.
165438+1October 2 1 On the afternoon, we went to the company in Cologne, Henan Province by bus and started our new internship.
Cologne company mainly produces all kinds of evaporators and condensers, and the condenser workshop is the first to enter. I saw that various types of copper-aluminum tubes became condensers after bending, welding, testing, film covering and other processes. After packaging, it can be listed.
The second workshop visited is the account blowing factory, which consists of several working areas, such as pretreatment area, coil area, riveting area, shearing area, vulcanization area, paint dipping area, film covering area, scrap area and finished product storage area. The product has been completed by many processes, such as coil pipe process, assembly welding process, leakage test process, low pressure pipe process, function test process, packaging process and so on. Leak testing is a key process, and the key parameters are: time and pressure.
Cologne mainly produces condensers and evaporators of Haier, Royalstar and other brands of refrigerators, such as 196DT or 188K/A refrigeration tube-plate evaporator and Royalstar refrigeration tube with model 205 or 192.
In Cologne Company, my biggest feeling is that with the cooperation of various equipment and staff, the complex condenser and evaporator become a simple copper tube condenser or evaporator after completing various processes. In fact, equipment and instruments played an extremely important role in this period. Without all kinds of equipment and instruments, it is difficult to produce even a simple screw, let alone mass production.
Part VII: Visit Jinlong Group
165438+1On the morning of October 22nd, I arrived at Jinlong Group by bus early. When I got off the bus, the magnificent architecture and magnificent scenes of Jinlong Group told me that Jinlong Group would be the most powerful enterprise I visited during my internship these days.
Sure enough, just entering the door, the words "Copper Pipe Engineering Research Center of China Academy of Sciences" and "Post-Doctoral Research Center" came into view. I was shocked and proud to have the opportunity to practice here.
At 9: 00 15, under the arrangement of the company's leaders, we watched the "Jinlong group propaganda film", and I still remember a sentence in it-if the compressor is the heart of the air conditioner, then the copper tube is the blood vessel of the air conditioner. Subsequently, the company leaders made an important speech, which can be summarized as follows:
1. Introduction of Jinlong Group;
2. The role and position of copper tube in China copper industry;
3. The importance of corporate culture;
4. The purpose of the enterprise.
In the "promotional film of Jinlong Group" and the speeches of company leaders, I got a preliminary understanding of Jinlong. With an annual output of 350,000 tons, Jinlong Group has branches in Shanghai, Zhuhai, Chongqing, Yantai and other places, mainly producing all kinds of copper pipes and metal parts with a diameter of 3.8-30 mm, a weight of 80-300KG and a length of 5-200 m. The company aims at "creating quality products for customers, creating value for employees and creating wealth for society" and "understanding, support, loyalty and dedication". At present, we have 1 1 modern high-precision copper coil production line, 13 specialized copper coil production workshop, and two fluorine-free copper tube production lines for refrigerators. All the key equipment are cutting-edge equipment from SMS, SCHUMAG, JUNKER and INDUGA companies in Germany, MRB company in Britain, NDUCTOHEAT company in Australia, OLIVOTTO company in Italy and OUTOKUMPU company in Finland.
Later, I visited Xinxiang Sales Department No.2 Factory and Xinxiang Sales Department No.3 Factory. The large and complicated equipment opened my eyes. Although I don't know how they work, the orderly team and complete production line are enough to prove the advantages and strength of Jinlong.
Later, under the explanation of the staff, it was a "big harvest", especially the cleaning of copper pipes and the production of internal threads of ACR copper pipes. The cleaning of copper tubes must use special cleaning agents and be very careful, because it is closely related to the future use of copper tubes. Because the production of ACR copper tube involves company secrets, we have a simple understanding of its characteristics and look at the products. As a large enterprise, Jinlong Group plays an important role not only in China copper industry, but also in the global copper industry. However, it is a pity that most of Jinlong's production lines, equipment and technology are imported from abroad, and there is almost no "achievement" of our national enterprises. This has also exposed the backward technology in China, where technology is controlled by others.