Common trimming methods for manual trimming of rubber products
Manual trimming is an ancient trimming method, including punching the rubber edge manually with a punch; Remove the glue edge with scissors, scraping tools, etc. The quality and speed of hand-trimmed rubber products will also vary from person to person. It is required that the geometric dimensions of trimmed products must meet the requirements of product drawings, and there shall be no scratches, scratches and deformation. Before trimming, you must know the trimming parts and technical requirements, master the correct trimming methods and use tools correctly.
In the production of rubber miscellaneous parts, trimming operations are mostly different forms of manual operations. Due to the low efficiency of manual pruning, many people are often mobilized to prune when production tasks are concentrated. This not only affects the work order, but also can't guarantee the product quality. Therefore, we should consider adopting more effective technological measures (such as using a molding die without flash) or using various trimming equipment for trimming.
Mechanical dressing
There are mainly punching, grinding wheel edging and circular knife edging, which are suitable for specific products with low precision requirements. It is the leading dressing method at present.
1) mechanical punching and trimming The rubber edge of the product is removed by means of pressure machinery, punching die and punching knife. This method is suitable for products and model products, such as bottle stoppers and leather cups, whose rubber edges can be placed on the bottom plate of stamping die or punching knife. For products with high glue content and low hardness, the method of impact trimming is usually adopted, which can reduce the unevenness at the back and the side depression caused by the high elasticity of the product. For products with low glue content and high hardness, the knife-edge die can be directly used for punching. In addition, punching can be divided into cold cutting and hot cutting. Cold cutting refers to punching at room temperature, which requires higher punching pressure and better punching quality. Eagerness refers to avoiding contact with products at high temperature for too long when stamping at high temperature, which will affect the quality of products.
2) Mechanical trimming is suitable for trimming large-sized products, and tools are used. The cutting machines on one side are all special machines, and different kinds of products use different kinds of knives. For example, after the tire is vulcanized, there are rubber strips with different lengths in the air holes and exhaust pipes, so it is necessary to take out the rubber strips with grooved tools when the tire is rotating.
3) Mechanical grinding and dressing For rubber products with inner holes and excircles, grinding is usually adopted. Abrasive tool is a grinding wheel with a certain particle thickness, so the grinding dressing accuracy is low, the grinding surface is rough, and it may contain residual sand particles, which affects the use effect.
4) Low-temperature shot blasting trimming For precision products with high trimming quality, such as O-rings and small cups, this method can be used for trimming. Use liquid nitrogen or dry ice to quickly cool the product below the brittle temperature, and then spray metal or plastic pellets at high speed to break and drop the flash, so as to finish trimming.
5) Low-temperature brush grinding and trimming It is to brush off the glue edge of the jelly product by two nylon brushes rotating around the horizontal axis.
6) Low-temperature roller trimming is the earliest freezing trimming method, which uses the impact force generated by roller transformation and the friction between products to crack and fall off the raw edges of products that have been frozen below the brittle temperature. The shape of the drum is usually octagonal to increase the impact force of the products in the drum. The rotating speed of the drum should be moderate, and the power can be improved by adding abrasive. For example, the trimming technology of electrolytic capacitor rubber plug is to trim the edge with a low temperature roller.
7) Low temperature oscillating trimming is also called oscillating freezing trimming. The products oscillate spirally in a circular sealed box, and there is a strong impact between products and between products and abrasives, which makes the frozen and brittle rubber edges fall off. Low-temperature oscillating trimming is better than low-temperature roller trimming, with lower product breakage rate and higher production power.
8) Low-temperature shimmy trimming is suitable for small or micro products with rich metal skeleton or micro silica gel products. Rubber edges in holes, corners and grooves of products are trimmed together with abrasives. ..
Freeze trimming
The principle of the special freezing edger is to make the finished product's burr brittle at low temperature by using liquid nitrogen (LN2), and to remove the burr quickly by using specific frozen particles (pellets) to impact the burr. The equipment has high production efficiency, low labor intensity, good trimming quality and high degree of automation, and is especially suitable for pure plastic parts. Widely used in products, it has become the mainstream technical standard. But this kind of equipment is expensive and the running cost is high.
Non-flash mold
Using a flash-free mold for production, trimming work becomes simple and easy (flash can be pulled off as soon as it is pulled, so this mold is also called a tearing die). The forming method of the flash-free die can completely omit the trimming process, improve the product quality and usability, reduce the labor intensity and production cost, and has broad development prospects.
Rubber classification 1, natural rubber
Mainly rubber hydrocarbon (polyisoprene), containing a small amount of protein, water, resin acid, sugar and inorganic salts. High elasticity, high tensile strength, excellent tear resistance and electrical insulation, good wear resistance and drought resistance, good processability, easy adhesion with other materials, and comprehensive performance superior to most synthetic rubbers. Disadvantages are poor anti-oxygen and anti-ozone ability and easy aging and deterioration; Poor oil and solvent resistance, low acid and alkali corrosion resistance; Heat resistance is not high. Temperature range: about -60℃~+80℃. Manufacture general products such as tires, rubber shoes, hoses, tapes, insulation layers and sheaths of wires and cables. It is especially suitable for manufacturing torsional vibration eliminators, engine shock absorbers, machine supports, rubber-metal suspension elements, diaphragms and molded products.
2. Styrene butadiene rubber
Polymer of butadiene and styrene. Its performance is close to that of natural rubber, and it is the general synthetic rubber with the largest output at present. Its characteristics are wear resistance, aging resistance and heat resistance, and its texture is more uniform than that of natural rubber. Disadvantages are: low elasticity, poor buckling resistance and tear resistance; Poor processability, especially poor self-adhesion, and low strength of raw rubber. Working temperature range: about -50℃~+ 100℃. Mainly used to replace natural rubber to make tires, rubber sheets, rubber hoses, rubber shoes and other general products.
3. Butadiene rubber
It is a cis-structure rubber polymerized from butadiene. Advantages: excellent elasticity and wear resistance, good aging resistance, excellent low temperature resistance, low calorific value under dynamic load and easy metal bonding. Disadvantages are low strength, poor tear resistance, poor machinability and self-adhesion. Service temperature range: about -60℃~+ 100℃. Generally used with natural rubber or styrene-butadiene rubber, it is mainly used to make tire treads, conveyor belts and special cold-resistant products.
4. isoprene rubber
It is a cis-structure rubber polymerized from isoprene monomer. The chemical composition, three-dimensional structure and properties are similar to those of natural rubber, so it is called synthetic natural rubber. It has most advantages of natural rubber. Because of natural rubber, its elasticity and strength are slightly lower, its processability is poor and its cost is higher. Service temperature range: about -50℃~+ 100℃ can replace natural rubber to make general products such as tires, rubber overshoes, rubber hoses and adhesive tapes.
5, chloroprene rubber (CR)
It is a polymer made by emulsion polymerization with chloroprene as monomer. This kind of rubber contains chlorine atoms in its molecules, so compared with other ordinary rubbers, it has the advantages of excellent oxidation resistance, ozone resistance, incombustibility, self-extinguishing in case of fire, oil resistance, solvent resistance, acid and alkali resistance, aging resistance and good air tightness. Its physical and mechanical properties are also better than natural rubber, so it can be used as general rubber and special rubber. The main disadvantages are poor cold resistance, heavy specific gravity, high relative cost, poor electrical insulation, and easy to roll, scorch and stick to the mold during processing. In addition, raw rubber has poor stability and is not easy to store. Working temperature range: about -45℃~+ 100℃. Mainly used for manufacturing cable sheaths, various protective sleeves and protective sleeves that require ozone resistance and high aging resistance; Oil-resistant and chemical-resistant rubber hose, adhesive tape and chemical lining; Refractory rubber products for underground mining, as well as various molded products, sealing rings, gaskets, adhesives, etc.
6. Butyl rubber
It is a polymer of isobutylene and a small amount of isoprene or butadiene. The biggest feature is good air tightness, ozone resistance, aging resistance and high heat resistance, and the long-term working temperature can be below 130℃; Resistant to inorganic strong acids (such as sulfuric acid and nitric acid). ) and common organic solvents, which have good vibration absorption and damping characteristics and excellent electrical insulation. Disadvantages are poor elasticity, poor processability, slow vulcanization speed, poor adhesion and poor oil resistance. Service temperature range: about -40℃~+ 120℃. Mainly used as inner tube, water tyre, balloon, wire and cable insulation layer, chemical equipment lining and shock-proof products, heat-resistant conveyor belt and heat-resistant aging adhesive tape products.
7. Butadiene rubber (NBR)
Polymer of butadiene and acrylonitrile. It is characterized by excellent gasoline and aliphatic hydrocarbon oil resistance, second only to polysulfide rubber, acrylate and fluororubber, and superior to other general rubber. Good heat resistance, air tightness, wear resistance, water resistance and strong adhesion. Disadvantages are poor cold resistance and ozone resistance, low strength and elasticity, poor acid resistance, poor electrical insulation and poor polar solvent resistance. Working temperature range: about -30℃~+ 100℃. It is mainly used to manufacture various oil-resistant products, such as rubber pipes and sealing products.
8. Hydrogenated Ding Qing Rubber (HNBR)
Polymer of butadiene and acrylonitrile. It is obtained by completely or partially hydrogenating the double bonds in butadiene of nitrile rubber. It is characterized by high mechanical strength and wear resistance. When crosslinked with peroxide, its heat resistance is better than that of NBR, and other properties are the same as those of Ding Qing rubber. The disadvantage is that the price is higher. Working temperature range: about -30℃~+ 150℃. Mainly used for oil-resistant and high-temperature resistant sealing products.
9. Ethylene propylene rubber (EPM \ \ EPDM)
* * * Polymers of ethylene and propylene are generally divided into ethylene-propylene binary rubber and ethylene-propylene ternary rubber. It is characterized by excellent ozone resistance, ultraviolet resistance, weather resistance and aging resistance, ranking first among general rubber. Good electrical insulation, chemical resistance, impact elasticity, acid and alkali resistance, small specific gravity and high filling. Heat resistance can reach 150℃, polar solvents-ketones, esters, etc. , but not resistant to aliphatic hydrocarbons and aromatic hydrocarbons. Other physical and mechanical properties are slightly inferior to natural rubber and superior to styrene-butadiene rubber. The disadvantage is that self-adhesion and mutual adhesion are poor, and it is not easy to bond. Service temperature range: about -50℃~+ 150℃. Mainly used as chemical equipment lining, wire and cable sheath, steam hose, heat-resistant conveyor belt, rubber products for automobiles and other industrial products.
10, silicone rubber (q)
It is a special kind of rubber with silicon and oxygen atoms in the main chain, in which silicon plays a major role. Its main characteristics are high temperature resistance (up to 300℃) and low temperature resistance (as low as-100℃), and it is the rubber with the best cold and high temperature resistance at present. At the same time, it has excellent electrical insulation, high stability to thermal oxidation and ozone, and great chemical inertia. Disadvantages are low mechanical strength, poor oil resistance, solvent resistance, acid and alkali resistance, difficult vulcanization and high price. Service temperature: -60℃~+200℃. Mainly used for making high and low temperature resistant products (hoses, seals, etc.). ) and high temperature wire and cable insulation layer. Because it is non-toxic and tasteless, it is also used in food and medical industries.
1 1, fluororubber (FPM)
It is an organic elastomer polymerized from fluorine-containing monomers. It is characterized by high temperature resistance up to 300℃, acid and alkali resistance, oil resistance, radiation resistance and high vacuum. Excellent electrical insulation, mechanical properties, chemical corrosion resistance, ozone resistance and atmospheric aging resistance. The disadvantages are poor processability, high price, poor cold resistance and low elastic permeability. Temperature range: -20℃~+200℃. It is mainly used in the national defense industry to manufacture vacuum-resistant, high-temperature resistant and chemical-resistant sealing materials, hoses or other parts on airplanes and rockets, as well as in the automobile industry.
12, polyurethane rubber (AU\\EU)
There are elastomers polymerized from polyester (or polyether) and diisocyanate compounds. It is characterized by good wear resistance and is the best among all kinds of rubber; High strength, good elasticity and excellent oil resistance. Ozone resistance, aging resistance and air tightness are also excellent. Disadvantages are poor temperature resistance, poor water and alkali resistance, and poor tolerance to aromatic hydrocarbons, chlorinated hydrocarbons, ketones, esters, alcohols and other solvents. Temperature range: about -30℃~+80℃. Tires are made of wear-resistant, high-strength and oil-resistant parts, gaskets, shock-proof products and rubber products.
13, acrylic rubber (ACM\\AEM)
It is a polymer of ethyl acrylate or butyl acrylate. Its characteristics are good heat resistance and oil resistance, and its performance is stable in lubricating oil containing sulfur, phosphorus and chlorine additives. At the same time, it has excellent aging resistance, oxygen and ozone resistance, ultraviolet resistance and air tightness. Disadvantages are poor cold resistance, water resistance, steam resistance, organic and inorganic acids and bases. It swells badly in water-soluble solutions such as methanol, ethylene glycol and ketone esters. At the same time, the elasticity and wear resistance are poor, the electrical insulation is poor, and the processability is poor. Working temperature range: about -25℃~+ 150℃. It can be used to make oil-resistant, heat-resistant and aging-resistant products, such as seals, hoses and chemical linings.
14, chlorosulfonated polyethylene rubber (CSM)
It is an elastic polymer obtained by chlorination and sulfonation of polyethylene. Excellent ozone resistance and weather resistance, superior to other rubbers. Good flame retardancy, heat resistance, solvent resistance, resistance to most chemicals and acid and alkali resistance. The electrical insulation is acceptable and the wear resistance is similar to that of styrene-butadiene rubber. Disadvantages are poor tear resistance and poor processability. Working temperature range: about -20℃~+ 120℃. It can be used as sealing material on ozone generator to make oil-resistant seals, wire and cable sheaths, oil-resistant rubber products and chemical lining.
15, epichlorohydrin rubber (CO\\ECO)
A polymer obtained by homopolymerization of epichlorohydrin or polymerization of epichlorohydrin and ethylene oxide. It is characterized by excellent solvent resistance to aliphatic hydrocarbons and chlorinated hydrocarbons, alkali resistance, water resistance and aging resistance, ozone resistance and scratch bath resistance. Benzyl is willing to fold the court? The happier, the more embarrassed. Is it true that the enemy's teres muscle is missing? 0℃~+ 140℃。 Can be used as rubber hose, seal, film and container liner, oil tank, rubber roller, oil seal, water seal, etc.
16, chlorinated polyethylene rubber (CM or CPE)