First, large-scale high-precision roller surface grinding method

The figure shows a large, high position precision roll made of 45 steel. Originally, when grinding on the M1450 universal grinding machine, use the center hole at both ends of the workpiece to locate, roughen the roller surface, fine grinding the bearing positions at both ends, and then use the bearing position to locate, use a dial gauge to check, the radial runout error of the roller surface. 10 times more than the pattern requirements (0.04 ~ 0.06mm). Trying to improve the number of trials has not been improved, far less than the radial requirements of the pattern of 0.003mm. Therefore, on the basis of continuous summing up of experience, the following new method was used to grind a few roots and reached the requirements of the pattern.

In the machining process, when selecting a positioning reference, the principles of reference coincidence, reference integration, and mutual reference should be followed to achieve high positional accuracy. When this roller is tested and assembled, it uses the bearing position as a reference. Therefore, in the grinding process, the bearing position should also be used as a positioning reference to achieve the principle of benchmarking, unity and mutual benchmarking.

In front of the grinding roller, first use the center hole at both ends of the workpiece to position the roller neck (two bearing positions) to the required level. Then check the bearing mounted on both ends of the bearing position, and use a nut to adjust the gap between the two bearings, to meet the requirements of the assembly.

When grinding the roller surface, first use the center hole at the two ends of the workpiece and the two tips of the grinding machine to position, and then use two closed center frames to stand on the outer circle of the bearing at both ends. After racking the center frame, the top ends of the two ends are withdrawn from the center hole of the workpiece. The centerpiece chuck is installed at the left end of the workpiece, and the grinding head frame is used to drive the workpiece to rotate to perform semi-finishing. During the final grinding, the grinding wheel must be properly dressed to keep the grinding wheel sharp and reduce the grinding depth to reduce the grinding force. It is also necessary to lower the hydraulic pressure of the grinding machine guide rails to reduce the thickness of the guide rail oil film to increase the rigidity of the guide rails, but the table must be made to move without crawling. After grinding to the process diameter, two or three strokes must be performed without sparking. After grinding in this way, on the large platform, the journal is supported on the bearing with two equal height V-shaped irons, and the dial of the dial is used to detect that the radial runout of each part of the roller surface is less than 0.003mm.

Second, the hollow elongated shaft grinding method

Workpieces with a wall thickness of about 1/6 of the hole diameter and an aspect ratio of more than 15 are called hollow elongated shafts. The blanks of this type of workpiece are mostly thick-walled seamless steel tubes or piston rods and test bars that have been drilled through the drilled holes. Their wall thickness is not uniform, and they increase the internal stress after turning the outer circle. When coupled with the hole block grinding outer circle, the heat generated can easily lead to deformation of the workpiece and non-uniform heat conduction, often produce single-sided grinding phenomenon (abrasive grinding spark intermittently, sometimes sometimes), directly affect the roundness of the workpiece after grinding, Therefore, it becomes a big problem in grinding.

Grinding the outer circle is necessary before grinding such workpieces. In order to facilitate the clamping, the two ends of the workpiece are first flattened and rounded in the inner hole, and then holes with C-shaped central holes are installed in the inner holes at both ends for easy loading and unloading. When grinding the outer circle, in order to prevent intermittent grinding and grinding of the workpiece after grinding and deformation and burn in the grinding, the hole at one end of the workpiece can be removed, the workpiece hole filled with water, and then the hole Plugging on. This not only eliminates the air in the hole, but also improves the heat dissipation and cooling effect, reduces the thermal deformation of the workpiece during grinding, and eliminates single-sided grinding and burns. After grinding, remove the hole and pour out the water. With the above method, dozens of hollow elongated shafts of different materials and specifications have been successfully ground in production, and satisfactory results have been obtained.

Stabilizer

It can slow down the reaction, maintain chemical balance, reduce surface tension, prevent light, thermal decomposition or oxidative decomposition. it mainly includes lead salts, metal soaps, organic tin, organic antimony, organic rare earths, pure organic compounds. Thermal stabilizers commonly used in industry mainly include lead salts, metal soaps, organic tin, organic antimony, organic rare earths, pure organic compounds, etc.

1.1 Organotin
(1) Excellent transparency The biggest advantage of organotin stabilizers is that they have excellent transparency. The use of organotin stabilizers in PVC formulations can produce crystalline products. Because of this, organic tin can be used in bottles, containers, corrugated boards, various types of rigid packaging containers, hoses, profiles, films, etc.
(2) Extraordinary thermal stability In terms of thermal stability, there is no other type of thermal stabilizer that can surpass it. Therefore, it is the preferred stabilizer for rigid PVC, and some varieties have better performance in soft products. Suitable for all PVC homopolymers, such as emulsion, suspension and bulk PVC, as well as vinyl chloride copolymers, graft polymers and polymer blends.
(3) The product is non-toxic. Most organotin stabilizers are non-toxic, and the migration of organotin stabilizers in rigid PVC is minimal. Therefore, organotin stabilizers are the preferred heat stabilizers for PVC for food contact.
(4) Good compatibility. Organotin stabilizers have good compatibility with PVC, so there is generally no precipitation on the metal surface, such as lead salt stabilizers and metal soap stabilizer systems.
(5) Poor lubricity Sulfur-containing tin stabilizers have poor self-lubricity. Therefore, many commercially available sulfur-containing organotins are equipped with lubricants to prevent hot melt from adhering to processing equipment during processing.
(6) High cost Compared with other types of stabilizers, the overall performance of organotin stabilizers is closer to the ideal stabilizer. However, all organotin stabilizers, regardless of their structure, have the main disadvantage that their manufacturing cost is much higher than that of lead stabilizers or metal soap compounds. In recent years, by adopting new synthetic technology, or reducing its usage in formulas, its formula cost has been reduced. In the 1970s, foreign countries developed low-priced tin products, which reduced the tin content, which also reduced the price to a certain extent.
1.2 Lead salt
(1) l Excellent stability experiments proved that among the commonly used basic lead salts, the heat resistance of sulfite is better than that of sulfate, and the heat resistance of sulfate is better than that of phosphite. The tribasic lead sulfate, which is widely used in the PVC industry, has a higher effective lead content and shows better thermal stability than other products.
(2) Excellent insulation. Because lead salt is non-ionic and non-conductive, it is inert, which makes lead salt stabilizers widely used in wire and cable industries.
(3) Excellent weather resistance. Many salt compounds can act as white pigments and can show strong covering power, so they have strong weather resistance.
(4) Poor transparency Transparency is a problem related to weather resistance. When used in wires, cables and record materials, there is no need to care about transparency, because most of these products are white or very dark black.
(5) Inexpensive lead salt stabilizer is the lowest price among all stabilizers. Therefore, despite the continuous introduction of new stabilizers, lead salt stabilizers still dominate the stabilizer market after half a century. The composite lead salt introduced to solve the dust and dispersion problem has increased in price, but still maintains a competitive advantage with other types of stabilizers.
(6) The toxicity of the toxic lead salt stabilizer limits its application in many occasions with strict hygiene requirements. For example, many countries have revised the lead content standards in drinking water, and it is no longer possible to use lead salt in PVC water pipes.
(7) Poor dispersibility The dispersibility of salt lead is poor, but the newly launched one-package product is equipped with lubricants, which solves the dispersibility problem to a certain extent. Because of the above characteristics of lead salt stabilizers, they are especially suitable for high-temperature processing. They are widely used in various opaque hard and soft products and cable materials, such as various pipes, plates, indoor and outdoor profiles, foam plastics, artificial leather, and wires. Cables, records, welding rods, etc. The most important lead salt stabilizers are tribasic lead sulfate, dibasic lead phosphite, and dibasic lead stearate.
1.3 Organic antimony
(1) Better stability. The organic antimony stabilizer has basically the same color stability and lower melt viscosity as organotin at the same temperature. In the twin-screw extrusion process, the effect is particularly outstanding when used in combination with calcium stearate. .
(2) The price of organic antimony stabilizer is much lower than that of methyl tin or butyl tin. In addition, the amount of organic antimony used is relatively low, so the use of organic antimony can achieve a better performance/price balance.
(3) The product is non-toxic. In the United States, when a twin-screw extruder is used to manufacture PVC pipes, the PVC water supply pipe manufactured with a formula composed of antimony stabilizers, calcium stearate and other lubricants conforms to the U.S. NSF (National Sanitation Foundation) )Regulation.
(4) Poor transparency and light stability. The transparency of organic antimony compounds is not as good as organotin stabilizers, and it is also lower than the barium/fu and calcium/zinc metal soap system. It is close to lead salts and has poor light stability, so antimony is stable. The agent is mostly used for indoor products without color requirements. The antimony stabilizer itself is also required to be stored in an opaque container.
(5) Poor lubricity. Antimony stabilizers have poor lubricity. Therefore, its use must be combined with a large amount of lubricant without exception.
1.4 Metal soap
(1) The tin soap stabilizer Fu soap is the best type of metal soap. Its advantages are also reflected in the absence of initial coloring, and can produce colorless and transparent products; excellent light stability; it has the effect of preventing precipitation and adhesion. . However, because tin salt is toxic, there are strict regulations on its manufacture and use in the Labor Safety and Health Law. In recent years, the use of Fuzao has shown a downward trend.
(2) Zinc soap stabilizerThe thermal stability of zinc-based stabilizer to PVC is extremely poor. The sample with zinc soap suddenly turns black when heated, that is, the so-called "Zine burning" phenomenon occurs, but it has the following advantages: The initial coloring is excellent; the effect of preventing fouling is good; it can improve the weather resistance; many zinc soaps are recognized as non-toxic stabilizers, so they can be used in non-toxic formulations with calcium soaps.
(3) Barium soap stabilizer Barium compounds have good thermal stability and good lubricity, but the red initial coloration occurs during processing, and it is easy to cause sticking to the roller.
(4) The stability of calcium soap stabilizer is poor, but it is recognized as a non-toxic additive in the world and has excellent lubricity.
(5) Other metal soap stabilizers used in the industry include magnesium stearate, file stearate, aluminum stearate, potassium stearate, etc., among which magnesium stearate is similar to calcium stearate and can be used Materials that are in contact with food; aluminum stearate is similar to zinc stearate, and is approved by the U.S. FDA and the Japanese Vinyl Chloride Food Hygiene Association for food packaging; Stearic Acid files and potassium stearate are also non-toxic products and belong to lead salts , Tin soap and barium soap substitute.
(6) The performance requirements of the composite metal soap stabilizer processing industry for stabilizers are various, and a single metal soap often cannot meet the use requirements, so the use of composite stabilizers has become a trend. A single metal soap compound is rarely used in the PVC industry, and it is usually a compound of several metal soaps. This compound is not a simple addition of properties, but takes advantage of the synergy between the components. The composite metal soap stabilizer generally includes the stabilizer main body (i.e. metal soap), solvent (organic solvent, plasticizer, liquid non-metal stabilizer, etc.), functional additives (auxiliary stabilizer, transparency modifier, light stabilizer, Lubricants, etc.). According to the form, it is divided into solid compound and liquid compound. According to the main component, it can be divided into calcium/zinc compound stabilizer, barium/fu compound stabilizer, barium/zinc compound stabilizer, etc. Among them, the calcium/zinc composite stabilizer has a pivotal role in replacing toxic metals because it is non-toxic.
1.5 Rare earth stabilizer
(1) Excellent thermal stability The thermal stability of rare earth stabilizers is better than traditional lead salt series and barium/zinc, barium/ho/zinc stabilizers. In some applications, rare earth stabilizers can partially or completely replace organotin.
(2) Good transparency. The refractive index of rare earth stabilizers is very close to that of PVC Resin, which can replace traditional organotin and be used in the field of products with higher transparency requirements.
(3) Excellent weather resistance. Rare earth elements can absorb 230-320nm ultraviolet light. Therefore, rare earth stabilizers have anti-photoaging effects and are suitable for outdoor products such as PVC corrugated boards and window materials.
(4) Excellent electrical insulation properties. Some rare earth multifunctional stabilizers can be used to replace lead salt stabilizers in cable material formulations, and their electrical insulation properties are comparable to lead salts.
(5) Non-toxic, safe and hygienic. Rare earth elements are low-toxic elements and have no toxic hazards to the human body in their production, processing, transportation and storage. Rare earth stabilizers are non-toxic products and can be used in food packaging and medical packaging products.
(6) The processing performance is slightly worse. In the case of a large amount of rare earth stabilizer, the roll release of the material is not ideal, and there is a tendency to press out. Generally, better results can be achieved by using stearic acid or calcium stearate in combination.
In summary, rare earth stabilizers can be used for water pipes, injection pipe fittings, window frame profiles, door panels, wire ducts, foam products, artificial leather, cable materials, soft and hard transparent products, food packaging materials, etc.
1.6 Auxiliary stabilizers Auxiliary stabilizers include phosphite, epoxy soybean oil, hindered phenols, etc., which mainly rely on the synergistic effect between metal stabilizers to improve the stabilizing effect, and are generally called co-stabilizers. In addition to compounds such as mesaminocrotonic acid ester, 2-phenyl saccharin, vein derivatives, and diketone can be used in combination with metal stabilizers to improve the effect of metal stabilizers, they also have a certain stabilizing effect. Such compounds are usually called pure organic stabilizers. With the development of PVC stabilizers today, the progress of metal stabilizers is relatively slow, and the research and development of auxiliary stabilizers are unprecedentedly active, which has constituted a major trend in the field of PvC stabilizers. Auxiliary stabilizers are rarely used alone, and are often used in conjunction with primary stabilizers to improve initial coloration or improve long-term stability.

Lead Salt Stabilizer, Compound Stabilizer,Pvc Stabilizer,Titanium Dioxide Anatase

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