Design, Analysis and Manufacturing of Double Scissors Lift Elevated by One Hydraulic Cylinder

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Design, Analysis and Manufacturing of Double Scissors Lift Elevated by One Hydraulic Cylinder

1Wubshet Yimer, 2Yanshuang Wang 12Mechanical Manufacture and Automation 12Tianjin University of Technology & Education 12Tianjin, China

Abstract – The following paper describes the design, analysis and manufacturing of a hydraulic scissor lift having two levels elevated by one hydraulic cylinder. Scissor lifting machine is hydraulically operated with makes lifting simple by eluding bending onward to lift manually because the table is regulating to be lifted at a preferred height. There are predominantly hundreds of workers for lift tables in industrial, warehousing and delivery services. The addition of this device (lift table) makes job quicker, harmless and easier. The overall objective of this paper is to design and manufacture a double scissors lift device elevated by one hydraulic cylinder that can be used in the automobile sector. The machine is tested by lifting different weights and it is successful and can lift up to the recommended weight of 270kg efficiently without any problem. Drafting & drawing of hydraulic system scissor lift is done using solid works.

Key words – Scissor lifting; lift table; hydraulic cylinder automobile sector, Solid works

  1. INTRODUCTION

    A scissor lift is a vertical lifting device that consists of a platform. The mechanism incorporated to achieve this function is the use of linked, folding supports in a crisscross pattern, known as a pantograph [1]. A scissor lift provide

    the most economic dependable and versatile methods of lifting loads, it has a few moving parts, which may only

    require lubricated. This lift table raises the load smoothly to any desired height. This mechanism is incorporated with a hydraulic cylinder and the top of the scissors is attached a table platform. This device will make use of the power generated from a hydraulic cylinder to raise or lower a platform. The scissor lifts can be classified as follows: Hydraulic lifts, pneumatic lifts and mechanical lifts.

    Hydraulic scissor lifts are very powerful tool for applying a ton of force on the platform plate of component which is equally distributed on scissor arms [2].

    A properly designed and equipped scissor lift enhances the logistic infrastructure, improving facilitys competitiveness. They are provide optimum solution for lifting awkward shaped objects to comfortable working heights with least worker fatigue and physical strain. It also reduces back and muscle injuries by avoiding inappropriate manual lifting techniques. Besides these it helps to save time. The beneficiaries are those who are working directly on lifting parts in automotive assembly and repair sector. This paper

    presents the design and manufacturing of a scissors lift elevated by one hydraulic cylinder for the automotive industry.

    The drawing of hydraulic scissor lift was done using solid worksFigure 1 shows the 3D modeling of double hydraulic

    scissor lift.

    Fig.1. 3D modeling of hydraulic scissor lift

  2. DESIGN ANALYSIS

    Concept selection

    The design was selected from an already made product in the market with modification in various parts and section to further enhance the functionality of the design.

    Design considerations

    Considerations made during the design and fabrication of a portable work platform being elevated by one hydraulic cylinder is as follows:

    • Functionality of the design

    • Manufacturability

    • Economic availability, that is general cost of materials and fabrication techniques employed.

    Research carried out in the automobile industry reveals that one of the heaviest components of the automobile car is the car engine which is of average weight of 272 kg. By this factor, the control weight would be 280 kg for safer design of the scissor lift table platform for assembly purposes in the automotive industry.

    Geometric Analysis

    Figure 2, shows geometry of the hydraulic scissor lifting

    max = opposite/ hypotenuse

    machine in raised position, which shows the various

    max =

    sin

    1 r

    (2)

    dimensions of the links including their orientation at this

    l / 2

    position.

    = 1

    250

    sin 560 / 2

    = 63.23o

    Figure 3, shows geometry of the hydraulic scissor lifting machine in lowered position, which shows the various dimensions of the links including their orientation at this position.

    Fig.3. Geometry of the scissor lift in lowered position

    Fig.2. Geometry of the scissor lift in raised position

    Considering the upper position (Figure 2)

    Considering the lowered position (Figure 3)

    l m2 r 2

    (1)

    X l 2

    2 2

    q 2

    2

    (3)

    2

    Where,

    l = the length of the arm

    Where,

    q = 90 mm (1/4 of the height of the scissor in lower position)

    m = 125 mm (1/2 of the distance between the arm in

    raised position)

    r = 250 mm (1/4 of the height of the scissor in raised

    X 560 2

    2 2

    90 2

    2

    position)

    Thus,

    l 1252 2502

    X 276mm

    2l 280 2

    l2= 560 mm (Scissor arm length)

    The maximum arm/linkage angle ( max)

    The maximum angle between the links and an imaginary horizontal line occurs at the maximum lifting height.

    Considering the lifted position (Figure2)

    X = 552 mm (the distance between the link/ arm in lower position)

    The minimum arm/linkage angle ( min)

    The minimum linkage angle between the links and an imaginary horizontal line occurs at the minimum (dead) height.

    Considering the lowered position (Figure 3)

    min = opposite/ hypotenuse

    1

    Input parameters

    S/N

    Component

    Symbol

    Value

    Unit

    1

    Max allowable load

    W

    280

    kg

    2

    Length of each scissor arm

    l

    560

    mm

    3

    Max. lift of the platform

    1000

    mm

    4

    Table platform dimensions

    LXB

    1000 x 520

    mm

    S/N

    Component

    Symbol

    Value

    Unit

    1

    Max allowable load

    W

    280

    kg

    2

    Length of each scissor arm

    l

    560

    mm

    3

    Max. lift of the platform

    1000

    mm

    4

    Table platform dimensions

    LXB

    1000 x 520

    mm

    Table I – Input parameters

    min = sin

    q / 2

    l / 2

    (4)

    1 90 / 2

    = sin

    560 / 2

    min = 9.250

    Actuator placement

    Figure 4, shows the actuator placement of scissor lift machine. The scissor lift uses the linear motion from a hydraulic actuator to produce large vertical displacement [3].

    For Load type 1

    Reaction forcs along the horizontal direction at the end of the first tier.

    Several actuator constraints must be considered when selecting a location. These constraints include the minimum retracted length, maximum extended length, and maximum

    available force. Constraints imposed by the lift include

    EX = -HX = -GX = F =

    = 707.07N

    W =

    2 tan

    2800

    2 tan 63.23

    strength of scissor members and space constraints imposed by the lift (and possibly by the payload). Proper actuator placement can significantly reduce the maximum force required of the actuator and also reduce the reaction forces at the lift joints [4].

    Horizontal force at the middle of the first tier =

    2800

    = 1414.14N

    tan 63.23

    W

    =

    =

    tan

    For load type 2, force couple EY=

    =1400N

    F WY

    =

    2 2

    2800

    =

    2

    FY = 1400N, F =

    Mz

    l cos

    , EY =

    F Mz

    2 = l cos

    Mz= 2 l cos X FY= 2×0.56cos63.23X1414.14

    =713.37NM

    CY = F =

    Mz

    2(l cos )

    or Cy= 2(

    713.3 )

      1. cos63.23

        =2800N

        CX = 0, EX = 0, FX = 0

        For loading type (3)

        F X= 0, CX = 0, CY = 0 and CZ = 0

        MX

        Fig.4. Actuator placement

        = 100

        EY = -DY =

        2

        Where b=52cm=0.52m, due to the symmetry of the system,

        FY = EY and GY = DY

        l 560

        8 8

        (5)

        Therefore MX = 2b X EY = 2X0.52×1400 = 1456Nm

        Effort required raising the load

        = 70 mm

        X = lcos100 (6)

        = 560 x cos100

        X = 551mm (actuator placement)

        To determine how much force you need, simply look at the angle of the pistons when the lift is collapsed. The force needed will be equal to the weight you want to raise times the sin of the piston angle [4].

        Fmax = Wma x sinmin

        = (280X9.81) x sin9.25

        = 2746 X 0.61

        = 442N.Effort required raising the load

        Table II – Results

        S/n

        Load type

        Quantity

        Symbols

        Value

        Unit

        1

        Max. lift of scissor arm

        63.23

        degr ee

        2

        Load type 1

        Vertical force at the end of first tier

        EY,FY,H Y,GY

        700

        N

        Horizontal force at the end of first tier

        EX,FX,H X,GX

        707.07

        N

        Horizontal force at middle of first tier

        CX

        1414.14

        N

        3

        Load type 2

        Vertical force at the end of first tier

        EY,FY,H Y,GY

        1400

        N

        Horizontal force at the end of first tier

        EX,FX,H X,GX

        0

        N

        Moment in the

        z-direction in 1st tier

        MZ

        713.37

        Nm

        4

        Load type 3

        Vertical force at the end of first tier

        EY,FY,H Y,GY

        1400

        N

        Horizontal force at the end of first tier

        EX,FX,H X,GX

        0

        N

        Moment in the

        x-direction in 1st tier

        MX

        1456

        Nm

        5

        Effort required to raise the load

        442

        N

        Strength and rigidity of the system

        The reaction force for load type 1 & 2 are all in the x-y, and are symmetric in the x-y plane. Because of this a cross bracing is recommended between left and right side of the lift to increase rigidity of the system. Reaction force from load type 1 & 2 will completely unstressed cross bracing in the left and right side of the system. It may be used for buckling purpose. While load type 3 have a reaction force that may stress cross bracing. In most application the scissor lift operate on a level ground. In this application is the most important significant load, although load type 2 and 3 may also be present if the load at the top of the lift is not centered. The type of load determines the type and the amount of cross-bracing required. Load type 1 & 2 do not stress cross bracing as is not too small but load type 3 affect cross bracing. [4]

  3. MACHINE TESTING AND RESULT

    The scissor lifting machine is tested by lifting three different weights (102, 153, 204 and 272 kg) in different heights. The first weight it has lifted is 102kg and it lifts the weight smoothly without any disturbance. Secondly, it is tested by lifting 153kg; this weight has also been lifted without any problem and thirdly it has tested lifting 204kg this weight also been lifted without any problem and Finally, by lifting 272kg. Which are the recommended weight and the weight is lifted smoothly with a higher effort than the 102kg and 153kg.

    Generally, the machine can lift the recommended weight 272 kg easily because the hydraulic piston makes lifting a high load easier and it does not have a disturbing sound.

    Fig.5. lifting test 1 (102kg)

    Fig.6. lifting test 2 (153kg)

    Fig.7. lifting test 3 (204kg)

    Fig.8. lifting engine test 4 (270 kg)

  4. CONCLUSION

The design and fabrication of a portable work platform elevated by one hydraulic cylinder was carried out effectively meeting the necessary design criteria. The double scissors lift elevated by one hydraulic cylinder is operated by the pedal. The scissor lift can be design for average load, because the higher the load the higher the effort required [2]. The hydraulic scissor lift is easy in use and does not required tedious repairs. It can also lift heavier loads. For the given dimensions the scissor lift can high a load up to 280 kg to the height of 1000mm. Hence, its extensive application in industries, hydraulic pressure system, for lifting of vehicle in garages, maintenance of huge machines, and for staking purpose.

REFERENCES

      1. Thorat, S.G., A.R. Chiddarwar, and S.P. Prusty, Design and Construction of Hydraulic Scissor Lift. 2017.

      2. Momin, G.G., et al., Design, manufacturing & analysis of hydraulic scissor lift. International Journal of Engineering Research and General Science, 2015. 3(2 Part 2).

      3. Lee, S.-w., O. Kwon, and K.-H. Rim, Analysis and design of long-stroke linear actuators. Journal of Mechanical Science and Technology, 2014. 28(8): p. 3197-3202.

      4. Spackman, H., Mathematical Analysis of Scissor Lifts. 1989, NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA.

      5. Doli Rani, Nitin Agarwa land Vineet Tirth. Design and Fabrication of Hydraulic Scissor Lift. MIT International Journal of Mechanical Engineering, Vol. 5, No. 2, August 2015, pp. 81-87 ISSN 2230-7680 © MIT Publications.

ACKNOWLEDGMENT

I would like to appreciate the following: For my advisor Professor Yanshuang Wang for fruitful comments of the paper; Assistant professor Habtamu Beri for helpful comments at several stages of this study.

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