1 introduction1.1 Step into the furnace1.1.1 Step into the furnace overviewAs western capitalist society in the 18 th century since the industrial revolution, the development of the society entered a new speed. According to the statistics in the industrial revolution in the world before the usage of the per capita steel is less than 5 kg. However, now of the social development to the ownership for 418 kg per capita steel. More and more steel structure appear in socialist construction. So steel has been now the main material of social development. And even once the shortage of supply. This prompted the steel industry is growing rapidly. To the year 2007, the world GangTieLiang has reached nearly nine hundred million tons. But because technology Co., LTD, add people to use more widely, steel emergence of steel more demand. So the steel and iron the smelting technology constantly improved.The first step in 1967 a beam furnace put into production. China 1979 years of production walking beam furnace is 32.5 meters long, production capacity of 270 tons per hour. Walking beam furnace stove than push steel have many advantages, thus become the first choice of rolling mills new furnace type. The scale of the steel rolling broadband is large development, walking beam furnace is one of the characteristics of furnace long from push steel, and can adapt to limit the length of mill production growth hour of the situation. Beijing steel design research institute nearly 20 years design of production more than 40 buildings stepping furnace, already pervaded strip, finances, great wire, strip steel, seamless tube, KaiPi, forging and other steel and steel belt factory, in 1994 have put in taigang, meishan strip factory of walking beam furnace rated output, respectively for 180 t/h and 280 t/h, chongqing iron and steel institute of design for pangang during the 1450 factory design walking beam furnace, rated output for 150 t/h, also put into production in 1992.Early heating furnace interior is a continuous type push with steel machine, it is the role of ingot or billet in turn push in charging. In the end the material, the furnace of steel machine can push will heating good from the other end of the billet reheating furnace out. In side out of the furnace of material, push the steel billet machine will be launched to the material position, again by the steel ingot machine will be out; Now most use is stepping type mobile device. Step into the furnace heating temperature even, heating time fast, high output, and big production flexibility and may, when necessary, will furnace empty blank. Heated, the blank of the surface of the water pipes under small black imprint, blank temperature even, heating efficiency is high. Heating special steel is, can be met on the surface quality of the blank (oxidation, decarburization, scratch, etc) height requirements; Heating large panel, as the slab temperature even, to reduce the thickness different rolling. So now stepping typefurnace in the hot rolled strip workshop and small and medium-sized steel rolling workshop have been widely used.From the 1950 s due to step into the furnace and the emergence of the mobile devices to mature, in many steel plate and small steel production are a good application. As a modern metallurgy industry is generally used a furnace, and his advantage worth learning.Step into the structure of the furnaceA, furnace bottom structureFrom the structure of the stove, see the step furnace is divided into heating stepping type furnace, heating up and down the step type furnace, double walking beam stepping type furnace, etc.On the step heating furnace heating device upside has only just as its name implies, fixed beam and mobile leung is heat-resistant metal production, fixed furnace bottom is refractory lining. The stove is basically no water-cooling elements, so the heat consumption is low. The stove can only single heating, general for a thin billet heating.And pushed steel as furnace, in order to meet the need of the billet heating big, stepping type furnace is also gradually development under the heating of the heat of the up and down, appeared to step into the furnace. The stove is equivalent to push steel type furnace of furnace bottom water pipe into a fixed beam and mobile beam. Fixed beam and mobile beam with water-cooled stand pipe support. By water cooling tube beam also form, with refractory plasticity bandage, outside a heat resistant alloy above the saddle type slippery course, similar to the guide on pusher-type reheating furnace of furnace bottom longitudinal pipe. Furnace bottom is of built on stilts, can realize double heating (step type furnace and billet is not close to the billet together, and there is a gap, can think is heated) all. Heating under general can only use side burner, because pillar blocking the end burner flame direction, if want to the burner, the need to change the structure of the pillar type. Heat can be used on axial end burner, you can also use the burner or top burner heating. Considering the axial burner flame along the length direction the temperature distribution and the control of the temperature, some each large step type furnace in each of the boundary between the heating furnace roof are clearly under pressure, and heating under paragraphs with between wall, in order to avoid the interference between each temperature; So this step type furnace stove temperature control along the length of the more flexibility, if the stove is larger, the flame length and width of the relatively short time, can be installed on the roof in flat flame burner.B, a transmission mechanismStepping type furnace is the key equipment moving beam transmission mechanism. The transmission way points mechanical transmission and hydraulic pressure drive two kinds. So far as the widely used hydraulic transmission way. Modern large-scale furnace mobile beam and the above billet weighs hundreds of tons, use hydraulic transmission mechanism, stable operation, the structure is simple, the operation speed control is accurate, cover an area of an area small, equipment, light weight, than the mechanical transmission has obvious advantages. Hydraulictransmission mechanism as shown in figure 2 to 12 as shown. Figure 2 to 12 b, figure 2 to 12 c, figure 2 to 12 d three structural type is now more common. Our country to apply more common for figure 2 to 12 c shows the inclined piece of slippery wheel. To the piece of slippery wheel as an example of the action principle: walking beam (mobile beam by lifting the use under) walking beam and the crust with a beam of two parts. Crust beam through the roll wheel, the next step into the role the beam, the next step beam by tilting the slider bearing in the roll. Fluctuation walking beam respectively by two hydraulic oil cylinder driving, beginning crust beam stationary, and rising hydraulic cylinder drive walking beam along the slider cant drive up, finish up movement. Then rises hydraulic cylinder makes the next step beam stationary, and level hydraulic cylinder will affect beam along horizontal direction, forward trip ends, in the same way down the action of a back and finish, ending a movement cycle.In order to avoid in the process of lifting vibration and impact, in the up and down and accept billet, walking beam should slow down among. When a start and stop the level should be considered a buffer to slow down, to ensure the smooth movement of the beam, avoid the beam slab wipe move. Way is to change the flow of variable speed pump to adjust walking beam operation speed. Due to step into type furnace is very long, excessive temperature difference fluctuation two sides, the different linear expansion will cause the beam bending and uplift. In order to solve this problem, the beam will present some into segments, paragraphs with the expansion of the gap between certain deformation, though, but can't avoid bending degree is reduced greatly, and not affect the normal work of the stove.C, seal institutionsIn order to guarantee the step furnace activities (bed) can beam normal unimpeded movement in activities, (bed) and beam fixed beam (bed) to have enough between the gap, gap is commonly 25 mm or 30 mm, the step for the beam supporting beams is (or conduit) through the furnace bottom part is that it sports large enough the holes. Those cracks or although the existence of hole is necessary, but also easy to inhaled air cooling, heating quality and reduce the influence fuel efficiency, also may cause furnace gas to escape and harm the furnace of steel rolling equipment, under to step into the oven with sealing problem must be considered, there are two sealing structure, a slide type is a water seal, is, the former seal is bad, especially when a skateboard heated deformation after sealing function, couldn't be more water is the most used structure, sealed effect is better, the water seal water and water to seal groove by the sword of two parts, the separation of type and closed two kinds of structure, type structure have move bed and fixed bed double sword for clear water, slag; Closed structure only move water bed knife, take up the space is little, the advantages of compact. Move the width of the slot water bed end to ensure that more than moving bed the length of the water level, the trip has set a slag, open by a crack in the furnace bottom dropped oxidized scale with flow out regularly.Have to mention here, are used only in the 1950 s (relatively) steel industry, for steel because of the special hydraulic drive itself that made its develop very slowly. To the 20 th century hydraulic transmission technology from theory to practice of using just basic mature. In the 21 st century hydraulic technology application willmark a national base level of industrial development. In step furnace mobile device hydraulic transmission systems, hydraulic transmission as providing dynamic beam the power source of the sports plays a vital role. How to design and high quality hydraulic device is directly affect the quality of a billet sintering.Early heating furnace interior is a continuous type push with steel machine, it is the role of ingot or billet in turn push in charging. In the end the material, the furnace of steel machine can push will heating good from the other end of the billet reheating furnace out. In side out of the furnace of material, push the steel billet machine will be launched to the material position, again by the steel ingot machine will be out; Now most use is stepping type mobile device. Step into the furnace heating temperature even, heating time fast, high output, and big production flexibility and may, when necessary, will furnace empty blank. Heated, the blank of the surface of the water pipes under small black imprint, blank temperature even, heating efficiency is high. Heating special steel is, can be met on the surface quality of the blank (oxidation, decarburization, scratch, etc) height requirements; Heating large panel, as the slab temperature even, to reduce the thickness different rolling. So now stepping type furnace in the hot rolled strip workshop and small and medium-sized steel rolling workshop have been widely used.Heating furnace stepping type mobile device hydraulic transmission system is mainly composed of dynamic and static beam of beam. When billet reheating furnace was pushed it in the static beam, this time the billet heating temperature began to be. Heating furnace of steel rolling industry is must be equipped with heat treatment equipment. With the continuous development of industrial automation technology, modern rolling mills shall be equipped with large, highly automated walking beam furnace, the production should be consistent with high yield, good quality and low consumption, energy saving, pollution-free, and production automatic operation process requirement, in order to improve the quality of its products, enhance the market competitiveness of products. The heating furnace of steel rolling industry in our country, which has pushed steel type furnace and step into the furnace two kinds, but pushed steel type furnace is short, low yield of length, the burning of the big, improper operation will stick by the problem on the steel production to realize the automation management. Due to push steel type furnace is difficult to overcome shortcomings, and walking beam furnace is special stepping on organization, in furnace rectangular steel pipe to do exercise to leave space between, steel pipe, steel tube and can be walking beam no friction between steel pipe, come out by over to completely eliminate the device slippery course scratching, steel tube heating section temperature difference is small, even heating furnace, long is not limited, high output, and production operation is flexible and other characteristics, its production meet high yield, high quality, and low consumption, energy saving, pollution-free, and production automatic operation process requirement. The continuous, full automatic step furnace.1.1.2 To choose a backgroundIn the hot rolling steel rolling mills, need on billet heating. In order to better ensure steel surface quality, make the billet is heated evenly, using a step heating mode.Billet heating process goes forward in the movement for rectangular; That activity, from rising beam slab fixed beam raise; Activities, before the forward beam slab step one time. Activities, will be put down beam slab fixed beam; Beam back to the original position activities to complete a work cycle.Step heating overcome transductive billet heating surface and support beam (fixed beam) produced by the mobile friction surface wear; At the same time, overcome the transductive of interactions between the billet close, can make the billet away through the bottom of the oven, be helpful for billet heating. Because of the advantages of the unique step heating, so that in the modern metallurgical plant a wide range of applications. Step into the billet reheating furnace type products of good quality and high thermal efficiency, flexible operation, apply to DuoZhong profiles of the blank continuous type heat.Stepping type continuous reheating furnace by furnace bottom or metal beams of the rising water cooling down, forward, backward, the action of the material base step by step forward to the continuous reheating furnace. The stove has fixed furnace bottom and step into the bottom of the oven, or have fixed beam and walking beam. The former is called stepping bottom type furnace, the latter is called walking beam furnace.The furnace by fixed bed beam and walking beam composition. Walking beam to more than double round by the axis, the support frame go by lifting cylinder driving wheel, which makes walking beam rise or fall for sport. The upper roller directly and hold walking beam, and walking beam directly by another hydraulic cylinder driving, can be in roller on back and forward movement, which makes walking beam back and forward for sport.Through the operation of the cylinder, walking beam do mark movement, paragraphs rectangular forms of movement can adjust and operation method can continuously or manual operation. The same hydraulic oil source provide walking beam transmission, can also or alternating movement; And can reverse movement, used as a empty furnace of billet with.Hydraulic transmission has its irreplaceable superiority, mainly displays in:A, can get A output force or torque, and structure is not complex;B, can reach large range of stepless speed regulation, and in operation of direct regulation;C, easy to realize the overload protection;D, action quick, start, stop, and the reversing of fast response, the impact is small;E, the lubrication performance is good;F, easy to realize the generalization, the series and standardization, design assembly short cycle;G, easy to realize the automation and intelligent and numerical control technology combined.This topic design content is to design a step into the furnace roof up synchronous hydraulic system.1.1.4 Design schemeStep into the oven mechanical structure of the roller type is the slope of hydraulic drive. Level and movements are made by moving the hydraulic cylinder driving, step below the roller along the framework and inclined mesa.This structure has two layers framework, and the lower layer is to promote the framework. The upper level for mobile frame. In the ascension of the frame above and below are Ann, each wheel under a roller on the mesa, roller translation framework for the mobile use, mobile cylinder through the crank connecting and rotary joints with the framework connection, ascension cylinder by rotary joints under direct and framework connection. With the framework for guidance, with the roller framework level guidance. RollThe heating furnace step institutions and hydraulic system mainly by the double step into the frame, hydraulic cylinder, hydraulic pump and various valve parts is composed. As shown in figure: a layer to the next layer, marching framework for lifting frame. Travel by support roller and framework is fall in lifting frame on the table, lifting frame also through the back-up roller and roller falls on basis. When lifting frame in lifting the hydraulic cylinder driving in along the inclined rail left lifting movement, walking beam and travel with a framework for the vertical direction, lifting movement in the translation of the hydraulic cylinder of drive, in a horizontal direction for a movement, thus completing the whole cycle action.Hydraulic system improvementThe original system in lifting the hydraulic cylinder level pull move up part of the beam, can change it to the hydraulic cylinder placed in furnace bottom, while rising and the hydraulic cylinder roller cant keep the same Angle. This effectively solve the tension, hydraulic cylinder cavity push rod no stem cavity movement power do, also reduced the size of the hydraulic cylinder, easy to design and installation.Walking beam action as shown in figure 1 shows:Figure 1 walking beam action schemesWalking beam and move the peace all use electrohydraulic proportional valve to control, its advantage is flexible and convenient adjustment control, work smoothly. In the design process, should consider stepping liangping move may cause a lot of inertial impact, achieve accelerated, slowing down, constant speed, so as to realize the beam to characterize the dynamic thermal light, light, and has put by adding, deceleration effectively reduce the move motion inertia caused by the beam mechanical impact, falls on its own weight down.Through the PLC programming and deceleration curve, both set to avoid the impact of the damage the equipment, and improve the system of the positioning accuracy, through the PLC control synchronization roof up accuracy.。