What is a cold-tied precision tube?

Source:Haorui 　 Time: 2020-01-07 13:36:02　Hit:

　　Cold binding is to put the metal blank in the cold rolling equipment, at room temperature, through the pressure machine fixed punch pressure on the blank, so that the metal blank plastic deformation and produced parts processing method.

　　First, the basic type

　　1. Positive cold binding precision tube: when positive cold binding occurs, the movement direction of the metal and the motion direction of the punch are the same. The positive cold tie can make solid and hollow parts of various shapes.

　　2. Anti-cold-tying precision tube: when anti-cold-tying, the movement direction of the metal is opposite to that of the punch. Reverse kneading can be used to obtain various cup shapes.

　　3. Compound cold-binding precision tube: in cold-binding, the movement direction of one metal of the blank is the same as that of the punch, while the movement direction of the other metal is opposite to that of the punch. Compound kneading can make all kinds of cup, rod, barrel parts.

　　4. Radial cold-tied precision tube; In cold fastening, the movement direction of the metal is straight with that of the punch. Radial kneading can be divided into centripetal kneading and centrifugal kneading, radial kneading is used to make bevel gear, flower keyboard and other parts.

　　5. Forging and pressing precision tube: during upsetting pressing, the metal blank moves outward radially. Upsetting press is used to make flanged shaft parts or cup parts.

　　Positive cooling, reverse cooling and compound cooling are the three most widely used methods of precision tube cooling. The direction in which the metal moves is parallel to the axis of the punch. Therefore, there are a lot of data also called these three methods for the axial kneading. As mentioned above, axial kneading can produce a variety of solid and hollow parts, such as ball pin, spindle shell, shell, etc. Radial cold rolling is recently more than ten years to spread out, the first used for communication equipment number plate, bicycle flower keyboard.

　　The above are several basic deformation methods of cold-tying precision tube. With the development of cold-tying precision tube skills, sometimes cold volume die forging is classified as cold kneading.

　　It is widely used in the manufacture of cars, tractors, bearings, telecommunications equipment and appearance, as well as in light industries such as bicycles and sewing machines, as well as in the system of national defense industry, because of its remarkable advantages.

　　Second, the characteristics of cold tie skills

　　1. Cold-tied precision pipe fitting with precise size and smooth appearance: the general size precision of cold-rolled parts developed in China can reach 8 ~ 9 grades, if the desired smoothness is selected, its precision is second only to the refined polished appearance. As a result of the cold rolling process to make the parts, generally do not need to be reprocessed, a small number of only precision machining (grinding).

　　2. Save the original data: the application rate of cold-tied precision pipe fitting can reach more than 80%. For example, the utilization rate of piston pin in jiefang sedan is 43.3%, while the utilization rate of piston pin in cold kneading is 92%. And if the universal joint bearing sleeve used cold kneading, the use rate of information from 27.8% to 64%. Visible, choose cold kneading method to produce mechanical parts, can save a lot of steel and nonferrous metal data.

　　3. High production rate: with the method of cold-tie precision tube production of mechanical parts of the power is very high, especially the production of large quantities of parts, with the cold kneading method production than cutting processing several times, dozens of times, or even hundreds of times. For example, the car piston pin with the cold kneading method than with cutting processing to make progress of 3.2 times, and now with the cold kneading piston pin driving machine, so that the production rate further progress. The yield of one cold kneading machine is equivalent to that of 100 general lathes or 10 four-spindle active lathes.

　　4. Parts with mixed shapes can be processed: such as special-shaped section, internal teeth, special-shaped hole and blind hole, etc., these parts are difficult to complete by other processing methods, but it is very convenient to process with cold kneading.

　　5. Cold-binding precision pipe fitting has high strength, good rigidity and light weight: because cold-kneading adopts the cold-deformation strengthening characteristic of metal data, that is, the metal blank is in three-direction compressive stress during the kneading process, and the data after deformation is arranged in a fine and dense way, and has a continuous fiber flow direction, the strength of the parts has been greatly improved. In this way, low-strength data can be used instead of high-strength data. For example, the past use of 20Cr steel through cutting processing to make jiefang brand piston pin, now use 20 steel through cold rolling to make piston pin, through the function of the determination of the target, the cold rolling method is higher than the cutting method for piston pin.

　　This indicates that the piston pin can be machined with cold-tie precision tube instead of 20Cr steel.

　　From the above characteristics, it can be seen that the cold rolling skills and now a variety of processing methods, with outstanding superiority. This paved the way for cold rolling to replace cutting, forging, forging and drawing skills to make machine parts.

　　Three, cold tie precision tube skill development

　　The early stage of cold-tying precision tube technique is very slow, only a few soft metals (lead and tin) have been kneaded for a long time. At the beginning of the 20th century until the end of the age of 19, just start kneading harder non-ferrous metals (zinc, aluminum, copper, brass, etc.) as for cold rolled steel, because cold rolling demand a lot of pressure, the time cannot solve the kneading with steel mold materials, appropriate smooth agent with large tonnage press questions, such as long-term that cold rolled steel tube is very not easy and it is not possible.

　　In 1906, the Englishman t.w. coslett found that phosphate treatment of steel products was an ideal method to prevent rust, but it was not widely used because of the complicated process and poor economic benefit. However, the appearance of this rust method has greatly stimulated the enthusiasm to discuss more brief and useful new methods. Later, the steel blank with active connection equipment for zinc phosphate rust treatment only two minutes. Zinc phosphate treated blank surface with fat smooth agent or sodium soap film, and this film is not easy to fall off, kneading this kind of blank, the pressure is less. This discovery led to the discovery of an ideal steel surface treatment method - phosphating saponification method.

　　The appearance of phosphating saponification treatment of steel blank makes it possible to knead steel. In 1934, Germany used phosphating saponification method to successfully cold extruded steel pipe. During the second world war, the germans needed a lot of shell casings, when the supply of brass and lack, so the germans secret experiment with cold kneading steel shell casings, later, the selection of alloy tool steel as mold data, with cold kneading successfully extruded large quantities of steel shell parts.

　　After the second world war, the americans stole all the information about the cold kneading of steel by the germans, and began to use the cold kneading to secretly produce ordnance in the United States.

　　The cold rolling of steel pipe was officially used in civil industry in 1947.

　　In 1949, the United States announced test data on the mechanical functions of various cold-bonded steels. In 1950 and 1953, Germany published the data of cold rolling and the results of cold rolling test.

　　In 1957, Japan introduced a special cold rolling machine, beginning to select cold rolling skills in precision instruments and appearance. Seeing the economic benefits of this new skill, Japan soon put it to work making cars and electrical parts. Has become the primary processing technique in a wide range of industrial sectors.

　　In China, the cold rolling process before the founding of the People's Republic of China is very backward, at that time, only a small number of factories with lead, tin and other non-ferrous metal pipes or wire cold rolling, pipe goods.

　　After the founding of the cold kneading skills were developed. In the 1950s, cold rolling of aluminum, copper and their alloys began. Black metal cold rolling has been used in production since 1960s. Ten years of havoc, greatly affected the development of cold kneading skills. From 1978 on, the cold kneading skill was rapidly developed under the guidance of a huge policy of "independence and self-sufficiency". In recent years, with the development of the reform and opening up policy, with the vigorous development of national industrial production and scientific skills, cold kneading skills have also been rapidly developed.

　　At the end of 1970s, many universities, research institutes and factories in China carried out the cold kneading test and discussion, announced a lot of valuable papers, began to form a research and use of cold kneading skills of the army.

　　At present, China has been able to knead lead, tin, aluminum, copper, zinc and their alloys, low carbon steel, medium carbon steel, tool steel, low alloy steel and stainless steel, and even bearing steel, high carbon and high aluminum alloy tool steel, high speed steel and so on. The cold rolled pieces are of all kinds, weighing up to 30 kilograms and weighing as little as 1 gram. In the use of mold data, in addition to high-speed steel, bearing steel, high carbon and high chromium alloy tool steel, but also choose a lot of new model steel such as CG2, 65Nb, LD. In terms of kneading skill parameters selection and mold construction planning, optimization planning and computer-aided planning and production (namely CAD/CAM) were selected at the beginning to make mold construction more reasonable and kneading skill parameters closer to practice. In the field of cold rolling equipment, China has the ability to plan and manufacture cold rolling presses of various tonnage. In addition to the general mechanical press, hydraulic press, cold kneading machine, but also successfully choose conflict press and high - speed high - energy equipment for cold kneading production.

　　The development of science has a serious impact on the cold rolling skills, specifically, it is the computer in the analysis of skills, mold planning, production and skills process control of the use of cold rolling skills. China will continue to apply this new skill. To develop cold rolling skills, we should start from the following aspects:

　　1. Expand the scale of cold rolling skills to gradually replace casting, forging, drawing and cutting within a certain scale;

　　2. Improve the precision and appearance quality of cold-rolled products, and produce more disorganized products;

　　3. Expand the cold rolling with the original data varieties, discuss more ambitious surface processing and smooth method;

　　4. Further applied CAD/CAM and optimized planning, improved and accelerated mold planning and production, and developed more reasonable mold construction;

　　5. To find more suitable for cold rolling mold information and heat treatment methods, to extend the service life of the mold;

　　6. Further develop the discussion and application of new skills such as hot rolling, isothermal rolling, hydrostatic rolling and high-speed kneading;

　　7. Develop a multi-functional cold rolling mill suitable for cold rolling, so that the blank and parts can be safely and actively feed and output, so as to further improve the production rate.

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