764 刮板轉(zhuǎn)載輸送機結構設計含開題及7張CAD圖
764 刮板轉(zhuǎn)載輸送機結構設計含開題及7張CAD圖,764,刮板轉(zhuǎn)載輸送機結構設計含開題及7張CAD圖,轉(zhuǎn)載,輸送,結構設計,開題,CAD
英文原文
Applied Mechanics and Materials Vol.658(2014)pp 183-188 Submitted: 29.04.2014
(2014) Trans Tech Publications, Switzerland Revised : 22.05.2014
Doi:10.4028/www.scientific.net/AMM.658.183 Accepted: 27.05.2014
Stress Analysis and Optimal Design of the Housing of a Three-Stage Gear Reducer
COJOCARU Vasile 1,a*, KORKA Zoltan-losif 1,b
And MICLOSINA Calin-Octavian 1,c
1”Eftimie Murgu” University of Resita, Faculty of Engineering and Management, Department of Mechanics and Materials Engineering, Traian Vuia Square, No.1~4, 320085 Resita, Romania a*v.cojocaru@uem.ro, bz.korka@uem.ro, cc.miclosina@uem.ro
Keywords: gear reducer; housing stress; displacement; finite element analysis
Abstract. The design of the housings of the gear reducers is made, usually, using empirical equations based on the center distance (the distance between shafts). These equations can lead to inappropriate stresses distribution and inadequate material consumption at the final product. In the manufacturing of large series and in the manufacturing of the gear reducers/ gearboxes with large dimensions it is necessary an optimization of the housing dimensions. The use of the finite element analysis in this process, combined with experimental researches, can generate significant improvements. The paper is focused on the analysis of stresses distribution and displacements on the housing of a two-stage helical gear reducer with parametric dimensions and loads. The housing is subjected to a static finite element study. The optimization process aimed to minimize the total weight of the housing. The next features were submitted to dimensional changes: the thickness of the housing walls and the thickness of the ribs. The results presented as diagrams of stresses and displacements distributions show real opportunities to reduce the total weight of the housing and the material consumption.
Introduction
One of the major trends of the mechanical engineering is the design of compact equipment with lower mass and lower material consumption. On the gear reducers/ gear boxes this goal can be reach by an optimal design of the gearing [1,2] and of gear supporting elements (shafts, housing).
The design process of the helical gears reducers involves the calculations of the main parameters that influence the dimensions of the housing of the gear reducer: the center distance, the diameter of the bearings, the outside diameters of the gearwheels, the shafts lengths. The other dimensions of the housing are defined by empirical equations.
In the scientific literature of the gear engineering are listed various equations for the calculus of the thickness of the housing walls, δ [mm]. These equations are based usually on the overall length
(l) of the housing [3]: δ=(0.004...0.0005)?l+4，or on the total center distance (a) of the reducers[4]: δ=0.025?a+5. The value calculated for δ, is used in the calculus of the dimensions of the housing ribs and flanges [3]. This design algorithm can generate the oversizing of housing, increasing the mass of the reducer and the manufacturing costs. These conclusions lead to the necessity of optimization of the design process of the housing.
The complexity of the housing geometry makes difficult to accomplish the determination of the strains and stresses by analytical relations. Evaluation of the strains and stresses by experimental methods is expensive and it is difficult to extrapolate the results of the measurements. The use of the finite element simulations, validated through experimental researches, can generate solutions for a proper stress distributions and an optimal design of the gear housing [5,6]. The use of parametric models in the finite element analysis allows the rapid changes of the dimensions and the loads applied to the part. Thereby the analysis can be run for a wide range of typo-dimensions, decreasing the time needed to release a new product. The current research aims to highlight the possibilities of improvement of the housing of a two-stage helical gear reducer using finite element simulations.
Conclusions
The results of the FEM simulations performed on the housing of a two-stage gear reducer submitted to static loads show that the geometry and dimensions obtained from empirical equations can be optimized. This optimization can be made based on the FEM simulations validated by experimental measurements. The maximum values of the Von Misses stresses obtained for the geometries analyzed are far below the allowable limit of the steel used in simulations. The maximum values of displacements are within acceptable limits, however shall be deemed that these displacements can accentuate the housing vibrations in the dynamic loads conditions. This observation leads to the conclusion that the criterion of rigidity should be a priority in the designing process of the housing. The charts of stresses and displacements distributions allow the identification of the weak areas. The geometrical changes of the housing made in these areas generate adequate solutions with the best ratio between the mass decrease and the stress/displacement increase.
Acknowledgment
The work has been funded by the Sectoral Operational Programme Human Resources Development 2007-2013 of the Ministry of European Funds through the Financial Agreement POSDRU/159/1.5/S/132395.
References
[1] L. Tudose et al., Optimal design of two-stage speed reducer using two-phase evolutionary algorithm, International Journal of Mechanics, Issue 3, Volume 2, 2008, pp.55-66.
[2] O. Buiga, C.O. Popa, Optimal Mass Design of a Single-Stage Helical Gear Unit with Genetic Algorithms, Proceedings of the Romanian Academy, Series A. Vol. 13, No.3/2012,pp.243-250.
[3]D. Muhs,H. Wittcl,D. Jannasch, Roloff/Matck - Machinc Elements, in Romanian, Vol. II, Matrix Rom, ISBN 978-973-755-412-3, Bucuresti, 2008.
[4] I. Palade et al.,Gear reducers, in Romanian,Dunarea de Jos University,Galati,2008, available online at http://www.om.ugal.ro/om/biblioteca.
[5] M. Davis et al., Designing for Static and Dynamic Loading of a Gear Reducer Housing with FEA. Power Transmission Engineering Magazine, February 2010, available at www.powertransmission.com,pp.32-37.
[6] S.M. Patil, S.M, Pise, Modal and Stress Analysis of Differential Gearbox Casing with Optimization, Int. Journal of Engineering Research and Applications, ISSN: 2248-9622, Vol.3,Issue 6, Nov-Dec 2013. pp.188-193.
[7] V. Cojocaru, Z. Korka, C. Miclosina, Influence of the Mesh Parameters on Stresses and Strains in FEM Analysis of a Gear Housing, Analele Universitatii Eftimie Murgu, Fascicula I, anul XX, no.2, 2013, ISSN 1453 - 7397,pp.47-52.
[8] S.Radzevich,Dudley’s Handbook of Practical Gear Design and Manufacture, CRC Press, NewYork,2012, ISBN: 978-1-4398-6602-3.
[9] E.J.Hearn, Mechanics of Materials, Third Edition, Blutterworth Heinemann, Oxford, 2000.
[10]G.X. Zhang, E. Rigaud, J.C. Pascal, J. Sabot, Gearboxes: Indirect Identification of Dynamic Forces Transmitted to Housing Through Bearings, 4th World Congress on Gearing and Power Transmission,Paris, France, 1999.
Coal Face transport equipment Selection and introduction to selection of scraper transfer machine
Abstract) Coal Face Selection of appropriate transport equipment for coal mining face has an important influence on the selection design of coal mining face, On the various introduces the technical characteristics, scope of application and how to select various types of scraper conveyors, scraper transfer machines, and retractable belt conveyors.
Keyword) scraper transfer machine; selection; technical characteristics
1、Coal Face transport equipment Selection
Traction linked by the number and arrangement can be divided into single-scraper conveyor chain, bilateral links, double-center chain and the three links, and other four types. These bilateral links to various functions AFC Coal conditions, the use of a wider scope, the disadvantage is that there are two bilateral chain linked unforced absorbed phenomenon. Three bilateral links in the chain scraper conveyor developed on the basis of When the two chains not enough strength, an increase of a middle chain, the practice has proved that such a structure chain unforced absorbed form of the phenomenon than the bilateral chain scraper conveyor more serious, frequent broken link accidents, products are eliminated. Two-center chain-type compared with the bilateral links, the chain of uniform, bending performance advantages, but in the hard coal、large coal circumstances of the larger transportation to perform well. Small scraper conveyor single chain of more, but with the large-diameter circle in the chain, the chain increased strength, the German use of large-diameter circle of chain-linked heavy AFC, this form of chain conveyor To bear the load in the same circumstances, than the double-stranded chain of specifications to be larger.
a) Scraper conveyor of the transmission capacity must be equal to or greater than Shearer or the production capacity of coal plough. But Shearer face conveyor and the productive capacity of roadway with the mining area, transport roadway and upgrade the mine’s transport capacity of the infrastructure, the ability to prevent face-off, mining area or roadway and a lack of transport capacity “bottleneck” phenomenon. Scraper conveyor structure and form of traction Shearer, and walk-oriented institutions! Bracket and the end of Slipper of the supporting structure;
b) Scraper conveyor length of the chute and hydraulic support to match the width;
c) Scraper conveyor of the chute and hydraulic support the passage of the jack and connect devices with space to match;
d) Conveyor of the chute to rugged wear-resistant structure, a flexible;
e) In order to reduce broken link accidents, linked ring in the large-diameter, high-intensity direction;
f) Priority choice of two-motor-driven double-nose, to reduce the transmission size, the largest chain to reduce tension, reducing the nose and tail of the top area of control. Selection of priority short nose and short tail, but the head-and tail-in or corner of the plate should not be too large to reduce the pressure in the chain block friction loss.
2、reversed loader selection of principle
Bridge reproduced machine is actually a special structure of the heavy scraper conveyor, in the face conveyor section flat lane and scalable conveyor belt between the role of a reprint.
a) Reprint of the transportation capacity to be slightly larger than face scraper conveyor. To this end use of increased chute section (on both sides of the chute and baffle), increase speed linked (to change the second-reducer gear transmission ratio) or shorten the distance between scraper, and other measures;
b) Reprint of the gear in the nose of uniform, should be based on volume and distance to determine the size of the electrical power and the number of Taiwan. Priority should be optional single-motor drive, when the volume and greater distance, the optional dual-motor drive. Its transmission should try and face the same scraper conveyor to GM;
c) Reprint of the aircraft tail and face the conveyor connected to the matching. A lap and non-overlap in two forms, regardless of what form, should ensure that face scraper conveyor nose of a certain height unloading (normally 600~700 mm), in order to avoid face-scraper conveyor Linked to the end of coal;
d) Reprint of the nose are loaded walk in the small car, walking the structure and gauge car with retractable belt conveyor tail-supporting;
e) Reprint of the bridge deck and the Department of retractable conveyor belt of coal by the tail of the length of the overlap should be complementary;
f) Machine parts and reproduced the face scraper conveyor should do everything possible to GM, to facilitate the supply of spare parts and maintenance.
3、Retractable belt conveyor of the principle of selection
Scraper transport planes form the coal face, reproduced as bridge-to-trough uninstall the retractable belt conveyor, and then coal form flat lane transported to the section on the downhill or with the station. With the face of advancing to the section flat lane transport equipment to a more flexible elongate or shorten. Retractable belt conveyor is characterized by a set of certificates with its devices, this device from the temporary storage tape from the appropriate role, when the mobile tail, the reservoir with a corresponding device can be released or save a certain length of the belt.
a) Mining machine with the transport section of flat lane general optional retractable belt conveyor, and its production capacity to match reprint machine. According to choose a suitable throughput with bandwidth and speed;
b) Retractable belt conveyor for the laying of the general length of 500~1000 m-Taiwan, when a length of two series can not. Can also choose multi-driven conveyor belt, the length of up to 2000~3000 m;
c) Conveyor belt transmission device generally used double-drum drive, and priority should be optional single-motor drive, to avoid the load due to the electrical transmission equipment caused by the unequal distribution of power increases. When the single-motor power shortage # optional two-or three electrical transmission;
d) Storage devices with the activities of a drum, two and three (corresponding certificates with a two-tier, four-tier and six-tier) should give priority to the simple structure of single-cylinder structure. If the reservoir with a shorter length of the warehouse, they can choose two or three roller structure;
e) Tighten the structure of a device automatically tighten (adjustable tensioning force) and non-automatic tensioning device two categories, priority should be given to choose the former, to ensure that the tape is the appropriate tension;
f) Transmission drum machine or a head band of anti-skid tape and driving drum 9 skid) security installations and non-security devices are to choose the former, in order to prevent the tape skid cause serious damage or excessive temperature rise caused by adhesive tape on fire Incidents. Ordinary canvas with a belt and high-strength nylon with two batteries, should try to choose the latter, to reduce the thick belt, increasing distance. Tape a general belt and fire tape, the latter should be used to prevent fires.
g) Shift the tail installed with hydraulic and electric winch-and Fully-supporting, a pumping station system for emulsion priority should choose the former, no pumping station system can choose the latter;
h) Retractable belt conveyor by the tail on the length of the form and structure to be reproduced with the bridge of the bridge and walk the length of the overlapping structure of the Department of match;
i) Retractable plastic belt conveyor structure of the body-hanging wire rope, steel
Hanging-beam steel frame and floor-variety. Type of steel wire rope hanging with little, simple equipment, suitable for floor changes, easy to water conditions, but the operation to shorten the tail relatively trouble. Steel-framed floor-simple structure, demolition of convenience, is conducive to the use and maintenance, but the fuselage large amount of steel used, the floor changes have an impact on the rack, under specific circumstances appropriate choice.
In the same time, the laying and installation plan of scraper reloader should be made according to the specific conditions of the mine, but it is generally carried out according to the following steps and methods：
1. First, the tail is placed under the head of the working face conveyor, and then the bottom scraper chain is passed through the middle plate of the tail and then lapped on the tail sprocket.
2. Then lap the long scraper chain from the tail section by section, and lay the middle groove of the horizontal section, (at this time, no cable groove) at the same time, put the bottom scraper chain into the bottom groove of the middle groove, and connect the middle groove with dumbbells.
3. When connecting with the crusher, it is also possible to use the connecting dumbbells and splints to connect well.
4, the laying of grooves, convex grooves and climbing section of the bridge groove, according to the required height can be temporarily erected with square wood, and at the same time, the bottom scraper chain section by section into the lower groove.
5. Install the nose transmission part and self-moving device on the tail of the belt conveyor.
6. the bottom groove scraper chain from the aqueduct and the nose plate under the lead, bypassing the nose sprocket on the sprocket.
7. Connect the long scraper chain from the tail of the aircraft and put it into the upper chain path until the nose of the aircraft.
8. Install all hydraulic systems.
9. Install the chain tightening device to tighten the chain.
10. Install cable troughs and electrical systems.
11. If it is inconvenient to transport during installation, the head transmission device can be removed and transported into the well for re-assembly, but attention should be paid to protecting the exposed shaft head, flange stop and other parts to prevent dirty and damage.
After installation, the scraper transfer machine should be tested and run to prevent dirty and damage.
1、Before the test run should check
1.1. Check whether the electrical signal device, communication and lighting work normally.
1.2. Check whether the oil injection amount of the reducer is correct, and whether all the lubrication parts have been fully lubricated.
1.3. Check whether there are any missing metal materials or tools on the scraper transfer machine.
1.4. Check whether the hydraulic pipelines are well connected and whether there is leakage.
2、When the machine is idling should be careful
2.1 Check whether the operation of the electrical control system is correct.
2.2. Check whether the reducer and hydraulic coupler are leaking, abnormal sound and overheating.
2.3. Check the operation of the scraper chain and see if there is any phenomenon of stuck chain. Whether the scraper chain over sprocket meshing is normal, whether the tightness is appropriate, whether the scraper is installed in reverse, whether the bolts are loose.
2.4. Check the coordination performance of the electrical system of the crusher.
3、The scraper transfer machine should pay attention to the normal operation.
3.1. The reducer and motor and other transmission devices of the conveyor shall be kept clean to prevent overheating, otherwise it will cause damage to bearings, gears, motors and other parts.
3.2, the chain must have the appropriate pre-tightening force, the general head sprocket under the link relaxation for two pitch is appropriate (that is, slightly droop).
3.3. The transfer machine should avoid empty load operation to reduce wear and do not reverse without special circumstances.
3.4 Oil lubrication shall be carried out according to the specified position, oil type and time.
3.5. The transfer machine is strictly prohibited to transport non-coal materials.
When cape pushing high-grade coal face in the course of mining, will often encounter some fault ramps National Chiao Tung University (H>3m)-not pushing too hard, making a face similar to the fault system between the “triangle”-shaped pillar, the pillar under the triangular Fault can be divided into the direction of “being” triangle and the “inverted” triangle of two. More recycling of coal resources, the inverted triangle coal-mining, are often used along the fault trend, retaining a fault-coal, transport, dig a supplementary entry, face additional transport along the roadway normal progress, but added the roadway and transport planes To retain a mining method, that is reproduced after the maintenance of mining.
It is the most important feature: the direction of promoting the face of coal and reprint the opposite direction. The dig-mining tech
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