History of cranebuilding and crane household until now

15/11/2013 2:24pm

Автор: Kanov G.L.

Категории: engineering science

History of cranebuilding and crane household until now

Kanov

Gennadii Kanov

            In the CIS countries according to the "Pod’emtranstechnika” association there work 17  cranebuilding companies, which continue travelling cranes, portal bridge cranes and special cranes building in accordance with the chief institute "All-Soviet Union research institute of heavy engineering enterprises" documents and self-design projects. Earlier this institute published annually collected papers on solution of cranebuilding, operating, handling machinery and railway track maintenance and repair problems. Certain problems in a detailed and searching way are stated in numerous thesis works, where the guidelines for their solution are given. The integrated information in the best way is collected and represented in “ Crane guide”, Mashinostroenie publishing house, 1988, in two volumes under the general editorship of  M.M. Gohberg, Doctor of Engineering Science, professor.
In the eighties the total volume of travelling crane building in the USSR made six or seven thousands cranes annually and after 2000 it stabilized at ten—fifteen thousands per year.
            In spite of the limitations, mentioned in GOST 27584-88 “Travelling and portal bridge electric cranes”, ISO 8306 “Travelling and portal bridge cranes. Tolerance for cranes and railway tracks” and GOST 28648-90 “Crane wheels. Specification”, the quantity of crane types and the variety of engineering solutions of their units, especially wheels comprises thousands of titles. Herewith each cranebuilding plant works under self-design standards. The full list of crane types and their characteristics are given in the catalogue “Travelling cranes of general purpose”, Moscow, 1995.
            One failed to unify crane details and its units until now, that’s why every company using cranes solves the problem of the replacement parts by itself, mostly in the way of lost surface renewing by overlaying or producing the new wheels by maintenance service. If earlier the operating costs, handling machinery and systems maintenance were taken as they arise, then recent years these costs are rigidly limited with accordance of multiple increases of metal, surfacing materials and energy supply prices. As a result the problem of reliability increasing and endurance of details and crane units escalated sharply.
            According to literary sources the external value of wheel salvage towards the value of a new wheel makes, %

  • wheel dia 800mm the repair of one ledge 22, roller face 44, roller face and two ledges 62-75
  • wheel dia 900mm the repair of two ledges 22-36, roller face and two ledges 45-50.

            Herewith, as a rule, the ledges are repaired with the help of  4 times overlaying and the roller face – twice, that is limited to appearance of iterative seams in the wheels.
            Numerous monographs, normative-technical and special literature contain the information about all the items and aspects of handling machinery. But still it is essential the problem of reliability growth and the endurance of the cooperating pair railway track- wheel.
            In accordance with Public health regulations 111-18-75 for the railway track the displacement towards wall axis should not exceed 15-20mm, i.e. the rail axes nonparallelism is to be herein. Mutual displacement of join rails in track edges in plan and in elevation are to be 2-3 mm. Rails interface gaps are to be up to 4 mm. The rail bend from the straight line is to be up to 10 m (flexion) up to 15-20 mm.
In accordance with State Committee for Supervision of Safe Working Practices in Industry and for Mine Supervision 0.51 the rail wear on the roller face may be 4-8 mm, on the rail face surface 10 mm (5 mm at each side). These tolerances predetermine the wheel width between ledges, which can be reduced if the wheel construction can self-center towards the rail position.
            The projects devoted to solution of this complex task are of high priority nowadays. The analysis of patent information shows the attempts of self-center crane wheel creation, which partially compensates the railtrack disadvantages. However, it is impossible to escape the rail wear until there is a friction couple. The creation of travelling crane on the magnetic cushion solves the problem in a big way, but still the financial status of companies does not let to order such projects and the existing company infrastructure can not provide the maintenance of new generation technology. 
            The given work deals with creation and usage in manufacturing of crane wheels of pin and link type with shock compensator, that allows to increase the longevity of the pair railway track – wheel.

            Basing on a large body of researches and static information the main reasons influencing on the crane runways wear are:

  • the poor rigidness of bridge truss
  • the mismatched runway and ledges of traveling crane wheels profile
  • construction and the type of bridge rail
  • stress caused in crane runway elements that is higher than the chosen materials allow.
  • the low quality of bench-work and assembly and construction and erection work while crane and its runway erection
  • failures in the travel mechanism of crane bridge and crane runway elements
  • quantity, capacity and operating regimes of crane, working on the same railway track
  • violation of crane maintenance rules
  • simultaneous combine of the factors mentioned above accelerates the wear.

            For simplification of studying and analysis, all the existing crane runway damages are divided into two groups.
            The first group includes all the cases of crane runway breakdown by virtue of natural wear during the target life. The second group includes all the types of premature failures of any of these elements by the action of the project uncounted factors.

            The analysis of crane runway breakdown as a result of its certain parts natural wear is less actual than the study and disposal of principles causing premature failure of crane runway.
In the practical part of the work the following types of crane runway damages (wears) were specified:

  • all the types of bridge rail damages
  • the damage of rail supporting members
  • bed construction units of crane runway damage
  • bed clamps of crane runway to the beams damage
  • the upper surface of bridge rail damage
  • the post set of work shop columns.

             Cutting of the rail side face as a result of frame running wheels and bridge swash or local/general constriction of the distance between crane runways axes are related to the most common crane runway damages.
            While crane travelling, one side of a bridge overleap, running wheels ledges bearing against the side face of bridge rail cut down the facing as a result of bridge truss poor hardness and the absence of acceleration for running wheels.  When the wheels are exhausted the crane runs off the rails. High efforts arising while bridge blocking, stop not only the crane but also damage crane runway fastening, that in its turn requires long and costly repair. Usually while repairing the crane frame is strengthened by means of diagonal rod welding to the frame and to the cross beam walls, the specified running wheels are changed into the high wheels with smooth profile ledges and hereafter the lubricants for rails side face is used regularly. The last is not always acceptable as the lubricant ingress on the wheel and rail surface reduces the dragging, causing frictional sliding and scuffing.
            The rails side face cutting can be also caused in result of running wheels misalignment of axes or narrowing of distance between runway wheels centers in one half of the crane bridge truss.
            At rails joint the side face cutting and rolling surface damage is more intensive because of secondary actions of impulsive loads.
            The rail deflections and wheel slip causes the scalloping wear and potting on the upper working plane of rails.
            In result of action of fluctuating loads in rails the fatigue cracks are formed, that leads to cross breaking and the residual stresses and defects while rails welding at the attaching points as stress concentrators lead to the sudden rails damage with unpredictable effects.
            The non-standard rails and fastening installation, below-standard rails parts, high clearances at joints and disalignment (more than 5 mm) during the crane runways repair cause an accident.
            The mentioned reasons shorten the life of railway track from designed 8 years (at average) till the general maintenance 2-3 years.
            The working time of railway track shorten also in result of steel quality and hardness of race track and crane wheels ledges mismatches in comparison with hardness of bridge rails.
            In result of wheel wear unevenness there appears substantial difference in wheel diameters at different bridge sides, which leads to bridge cocking and heavy wear of wheel flanges and rails side face.
            The great impact on the crane runway and wheel flanges wear has assembly cocking of traveling wheels towards each other and the rails. The most typical cocking combinations are:

  • both wheels have cocking towards the rail on one side
  • one wheel has cocking, the other located on the other side of the transmission shaft is placed correctly
  • both driving wheels have cocking inside different sides towards the rails
  • both driving wheels have cocking outwards different sides towards the rails

            All the cases of wheel cocking lead to appearance of flexural stress, tensile stress and compression stress in the bridge truss and proportional deformations of crane metal structures depending on the combination of these stresses.  On the whole, all the bridge deformations in the temporary limits centralize their action in the places of wheel and rail contact. As a result all the crane wheels (4 or 8) operate under different loads and in different conditions. The bigger sampling length of the bridge, the bigger strain level and wheel load imbalance. Besides, the location of a loaded crab is very important, and the closer crab to column lines the higher crane cocking and its wear.
            The analysis of different information sources allows to draw conclusions that the wear rate of a pair rail-wheel predominates over the cross slip action and the long rolling leads to heavy wear only in regimes of slippage and scuffing. The wheel and rails wear is more intensive under the influence of impulsive loads.
            The locating accuracy of crane wheel on the axes, their alignment towards each other and axle body, rails alignment and difference in height, their flection and condition requires inaccessible exemplarity, that’s why the design crane and its units lifetime differs from the real terms. In Kirichenko’s monograph  “Crane runway” is mentioned that in case of crane excursion from the railway track on point more than 1'43''there may appear cross slip of wheels over the rails. That is why the solution of this problem may be automatic crane wheels.
            Installation tolerance of bridge crane traveling wheels is provided by GOST 24378-80 : departure from vertical plane of wheel end surfaces and from gear crown gear  general plane of end girder or balance-beam no more than 0,002D, D – the wheel diameter;   parallel misalignment of wheel general plains at rails bay no more than 22.5 m – less than 5 mm, at rails bay more than 22.5 m – less than 8 mm; the deviation of crane base length no more than 5 mm;  lack of perpendicularity of wheel end surfaces f = 2/1000D.
            The main dimension ratios of crane wheels are provided by GOST 28648-90 and technical regulations by GOST 28648-90.
            In Gohberg’s monograph “Metal constructions of carrying and lifting machines” is given the calculation methods of side forces affecting on the wheel ledges while friction on side head of rails. At average the side force rate equals to 0.1 from vertical action on the wheel, max. 0.15. These forces are vertical to the traveling direction of traveling wheel ledge and may be directed both inside and outwards the bay.
            Traditional decisions concerning increasing the life of a wheel is given in work of “Moscow branch office” “Hardening and increasing of endurance of crane traveling wheels".
At present time the method of traveling wheel computation according to Industrial Standard 24.090.44-82 is the most preferable. It includes three-dimensional stress state in zone of wheel contact with a rail and the wheel rate speed while its lifetime (in average 10000 rotations). The wheel diameter and the rail type is chosen depending on the highest deadweight load on the wheel (200-1000 kN) i.e. proportionally the crane capacity with account of its specific speed 1.0-3.0 m/s).
            As the railway track is more expensive and requirements for the rails are strict, the wheel should have the lower properties, i.e. it should be produced from the low-priced steel grades or iron with level of hardness after heat treatment 190-350 HBand the level of safe design stresses 600-900 MPa. So the wheels are regarded as replacement parts.
            In CIS countries the wheels are produces from steel forgings 45, 50, 75, 65 Mn, rolled steel 75 and 65 Mn, steel castings 55 and 35 MnA.
            In accordance with foreign literary sources recently the crane wheel are casted from high-grade cast iron with globular graphite and self-lubrication or from alloy steel. For example, according to alerting service No 5, Moscow 1981, in France the wheels are produced from forged steel 35C14 of chemistry: С-0,3…0,4, Мn-0,4, Si-0,35, Ni-3,2…3,7, Cr-1,2…1,5, Мо-0,2…0,3 with level of hardness 450-500 HB. As one can see, the level of wheels abroad increased by virtue of high-grade materials usage. Cranebuilding experience of Germany is given in two-volume book “Cargo cranes”, translation from German under the editorship of M.P. Alexandrova, Moscow, Machine building, 1981.
The problems of wheels force impact with rails are stated detailed in A.S. Konoplya’s thesis work, Leningrad, 1969
            The statistical analysis of lateral forces, appearing while crane travelling, is stated in A.N. Zubkov’s thesis work, Moscow, 1967.
            Kinematics and force interaction of bridge cranes with crane runways while restraining and speeding-up are stated in G.P. Ermakov’s thesis work, Chelyabinsk, 1973.
            The action of impulsive loads is analyzed in N.A. Lobov’s monograph  “Dynamic of cargo cranes”, Moscow, 1967.
            Hereafter, the author fulfilled research-and-development activities concerning making the design of crane traveling wheels of new generation, improving reliability and life of the pair wheel-rail thanks to the axially self-adjustment and dynamic forces absorbing, that reduces the operational costs. Wheel alternative constructions are protected by Ukrainian licenses No 76582 C2 from 01.08.06, No 77062 С2 from 16.10.06, No 85081 С2, MPK В66С 9/00, В60В 9/00 with confirmation of absolute-novelty.
            Due to the appearance of new crane wheels constructions with characteristics that are higher, than that of GOST and the manufacture is realized in accordance with project specific technical specifications, confirmed and registered at GosStandart in accordance with the established procedure. For example, offered in the license wheel constructions may be produced according to Technical specifications-31.7829-24439835-2000.
            All people, who are interested in solution of perpetual problems of crane household, should try to manufacture and test in commercial operations the new-generation crane wheels. The design of such wheels provides straightness of crane traveling with minimization of side forces and compensation of impulsive loads. This will solve in an integrated manner the foregoing problems of the pair railway track- crane wheel, improving the reliability and lifetime of the system with conforming operating expenses level recession.
            The technical and economic assessment for crane wheels of new generation can be developed in accordance with technology pull, considering the specific nature of enterprise performance and each crane. The formulation of a problem may be specified and agreed while negotiations concerning cooperation or licensing.
            As manufacturing of replacement parts does not require execution of special permits at public authorities, the wheel brassboard production can be fulfilled by the factory maintenance service of work drawing, designed by the order’s planning and design office with the author’s consulting participation relating to the concrete crane with its following participation when mounting of wheels on the crane and designer supervision in the period of operation till the wear limit.


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