The portable carbon monoxide detector learned that the Jiangsu Provincial Bureau of Quality Supervision issued consecutive batches of supervision, spot checks and risk monitoring quality analysis reports for a variety of stationery items. Some of the core fluids, correction fluids, erasers, and operating books detected excessive levels of toxic and hazardous substances. Among them, online product quality issues are more than those under the line. Portable carbon monoxide detector It is difficult for people to rest assured that the stationery that should be used by the children is safe to use. The reporter conducted an investigation. "Large taste, can't dare to give children!" On an e-commerce platform, many users leave a message under a correction fluid product. The analysis report of the Jiangsu Provincial Bureau of Quality Supervision pointed out that the quality of goods purchased from e-commerce platforms is generally low, and the number of items in the labels of pens, erasers, correction fluids, etc. is twice as high as that of physical stores, and the homework books purchased online are The pass rate is only 54.8% portable carbon monoxide detector. In September, the Quality Supervision Bureau of Jiangsu Province issued a series of quality inspections on supervision and spot checks and risk monitoring of various stationery products. It pointed out that more than 90% of the refills from the online and offline stationery samples exceeded the national recommended standards and exceed 9 percent. The rubber plasticizer formed exceeds the national recommended standards, and more than 90% of the operating paper contains a migratory fluorescent brightener. “Benzene-based substances are highly toxic to the human body. Plasticizers can affect children’s hormone system. The harm of fluorescent whitening agents is currently inconclusive. However, long-term skin contact may be absorbed by the body and adversely affect student health. "The relevant technical staff of the Jiangsu Provincial Bureau of Quality Supervision told reporters portable carbon monoxide detectors. Why are stationery products with quality problems and safety hazards still marketable and popular? A survey conducted by the reporter found that inadequate supervision, large consumer demand, and lack of rigid standards are the main reasons for portable carbon monoxide detectors. - Weak supervision, repeated sales of substandard goods. Some experts pointed out that the regulatory loopholes caused by unclear division of labor among government regulators and unclear power and responsibility are portable carbon monoxide detectors that are still an important reason for illegal products on the market. - The lack of rigid standards, merchants opt for "blindness." Qu Mei, senior engineer of the Consumer Products Testing Center of the Jiangsu Provincial Quality Inspection Institute, and Wang Guorong, deputy director of the Jiangsu Quality Technical Supervision Paper Printing Product Quality Inspection Station, told reporters that the general domestic reference standard for domestic stationery is “GB21027-2007â€. "General Requirements for Safety of Student Supplies", which gives the migration limits of eight heavy metal elements such as lead, mercury, and arsenic, but it does not require phthalates, toluene, ethylbenzene, xylene and other indicators in stationery. There is also no portable carbon monoxide detector required for the migration of fluorescent brighteners. - The demand is large, and free issuance is not enough. The reporter learned that although Jiangsu, Anhui and other places enjoy free stationery distribution, they are generally unable to cope with students' normal learning and living. In Anhui, the number of free workbooks is generally around 20 books per semester. However, most of them are divided into texts, picture books, three-line books, and Tianzi text books. Each page is about 20 pages in size and the portable carbon monoxide detector is not very bulky. Some experts pointed out that the regulatory loopholes caused by the unclear division of labor among government regulators and unclear responsibilities and powers are important reasons for the existence of illegal products in the market. Regarding the fact that "no use was found", Qiu Jianxin, associate professor of sociology at the School of Humanities and Social Sciences at Nanjing University of Aeronautics and Astronautics, said that the governance of the source and circulation should be implemented in a two-pronged manner. Only one end is good and cannot solve practical problems. In fact, it is to shirk responsibility for portable carbon monoxide detectors. . In addition, industry insiders also call for stricter standards. “At present, we have no strict scientific conclusions about fluorescent whitening agents and can't formulate standards out of thin air. However, for the people concerned, related departments should promote the development of relevant scientific experiments.†An expert from the Department of Chemistry of Nanjing University stated that portable carbon monoxide detection instrument. Kureike Electronic Technology Co., Ltd. is a professional manufacturer of toxic and harmful gas detectors, combustible gas detectors, combustible gas alarms, combustible gas leak detection alarms, toxic gas leak detection alarms, combustible gas detectors, four gas detection Instrument, gas alarm, gas alarm, natural gas leak alarm, gas leak alarm, gas detector, natural gas alarm, natural gas detector, gas detector, combustible gas sensor, gas alarm, carbon monoxide alarm company, All along, the customer is God, quality is life, the earth is the market, safety is a guarantee that has made a good reputation, and we take responsibility for the lives of people who use our products. We always keep in mind our every product and every A service maintains the safety of human life. It is our aim to not deal with defective products, not to develop defective products, and not to sell defective products. We keep in mind that providing a quality product is the best way to return the customer a portable carbon monoxide detector.
Tungsten carbide roller has characteristics of good wear resistance, high temperature red hardness, thermal fatigue resistance and thermal conductivity and high strength , have been widely used in high-speed wire rod, bar, rebar, seamless steel tubes, etc. Domestic production of tungsten carbide roller materials mostly WC- Co, WC- Co- Ni- Cr two series, and the content of Co, Co- Ni - Cr is in the range of 6wt% ~ 30wt%. From the use of perspective, tungsten carbide rollers has good mechanical properties, its flexural strength up to 2200 MPa or more, shock toughness up (4 ~ 6) × 10^6 J/ m^2, Rockwell hardness (HRA) is up to 78 to 90, widely in the high-speed wire rod rolling process, which is much higher than single-slot chilled cast steel or high speed steel rolls.Tungsten carbide is made of Tungsten Carbide Powder and binder phase (such as drilling, nickel, etc.), and then pressing and sintering, regardless of the conditions under cold rolled or hot rolled has excellent wear resistance, tungsten carbide rollers has been widely used in pre-finishing mill and finishing of high-speed wire rod currently. On the performance of tungsten carbide roller in hot-rolling wire rod , the material must meet the following requirements:
Tungsten carbide roller material design
Tungsten carbide roller category
Tungsten carbide roller production process control Carbide Roller,Carbide Ring,Mill of Rolling Line,Steel Wire Rod,Mill Rolling Finish Stand,Mill Roller Groove Type Luoyang Golden Egret Geotools Co., Ltd , https://www.hvafspray.com
1. Sufficient anti-fracture strength;
2. Good abrasion resistance;
3. The smooth surface finish;
4. Excellent corrosion resistance, thermal fatigue, thermal cracking performance.
Tungsten carbide roller rings can working in bad conditions , small profile rolling (especially rebar rolling) process conditions is harsher than the high-speed wire rod, and therefore corresponds to the profile rolling ,tungsten carbide rollers recommend using high binder phase carbide.
Pre-finishing all vehicles roller should ensure its high toughness, strength, rigidity and thermal conductivity, followed before considering its wear resistance. When designing each vehicles roller, pre-finishing materials should choose carbide grades of Co, Co- Ni- Cr binder content is high (greater than or equal to 25wt%) , requiring an average WC grain size of coarse (5μm ~ 6μm), to obtain a higher shock toughness, proper strength and hardness. For the finishing of the roller movements, particularly the last two rollers of the finish rolling, which suffered load is small, and high relative velocity of the material to be pressed (80 m / min ~ 120 m / min). In this case, the wear resistance of the roller to be the most important requirements, and must ensure the strength , timpact toughness and hardness of a reasonable match, so the binder of Co / Ni content ratio and the average grain WC control of particle size and other factors must have greater control in front of different pre-finishing rolling roll.
According to the structure of tungsten carbide rollers, it can be divided into solid tungsten carbide roller and composite tungsten carbide roller. Solid tungsten carbide rollers have been widely used in pre-finishing and finishing stands high speed wire rod mill (including fixed reducing the rack, pinch roller rack). Composite tungsten carbide roller is made of cemented carbide and other materials, and it can be divided into tungsten carbide composite roll rings and solid tungsten carbide Composite Roller. Tungsten carbide composite roll rings mounted on the roller shaft; solid tungsten carbide composite roller will be directly cast in the roll axis to form a whole, a large load is applied to the rolling mill.
Tungsten carbide rollers produced by powder metallurgy method, the key to its process control is the chemical composition of the material and the mixture was prepared, pressed molding, sintering and deep processing and other preparation process parameters.
1. Preparation of starting material (WC focus quality): As the WC raw material and quality control of the use of different levels of quality may fluctuate, resulting in adverse effects on microstructure.
2. Preparation of the mixture: Mixture preparation is the key to the production process of the roller, the roller of failure modes - trachoma, mainly generated by this procedure.
3. Pressing: roller pressing is an important process of the roller mill.
4. Sintering: roller sintering is to determine the final quality of the roller production processes, use of advanced low-pressure sintering technology, HIP sintering technology can greatly improve the performance of roller.
5. Deep processing: deep processing rollers have a greater impact on the quality and accuracy of the roller surface.