Scissor Lift , Gaffar G Momin, et al 2. Conventionally a scissor lift or jack is used for lifting a vehicle to change a tire, to gain access to go to the underside of the vehicle, to lift the body to appreciable height, and many other applications Also such lifts can be used for various purposes like maintenance and many material handling operations.
It can be of mechanical, pneumatic or hydraulic type. The design described in the paper is developed keeping in mind that the lift can be operated by mechanical means by using pantograph so that Fig: 4 ; Fatigue Failure of Hydraulic Scissor lift the overall cost of the scissor lift is reduced. In our case our lift was needed to be designed a portable and also work without consuming any electric power so we decided to to use a hydraulic hand pump to power the cylinder Also such design can make the lift more compact and much suitable for medium scale work.
Finally the analysis of the scissor lift was done in ansys and all responsible parameters were analyzed in order to check the compatibility of the design values [ ] Design, Analysis and Development of Multiutility home equipment using Scissor Lift Mechanism , Fig: 5 : Failure of Hydraulic Scissor lift due to Divyesh Prafulla Ubale, et al. The design module pallet case of ladders hence hydraulic scissors lift is designed to along with mechanism used for balancing is design in CAD overcome all these difficulties.
The design proposed is highly flexible with the equipment for senior citizens so that they can carry their manufactures requirement and its stability is analyzed under daily activities efficiently.
Also the equipment should be variable load. The result of the feasibility study showed a compact and cost effective. Lifting height achieved by scissor conspicuous shortening of working hours, and an alleviation mechanism is of 1 m from bottom level. Buckling and of manual labor The manufacturer required a pallet system bending failure analysis of scissor is also done in this paper. Comparing the three systems, we find and more new technologies are applied to lifting appliance pneumatic system rather advantageous over the other two.
All safety reducing the amount of vibrations. Considering the considerations are taken into account while designing involvement of the third system , where actuation of the equipment. Scissor lifting mechanism is designed to lift pallet is via servo motors is out of question ,as its highly person to desired height. A scissor lift mechanism is a device costly, requires frequent maintenance, and its load bearing used to extend or retract a platform by hydraulic means.
The capacity is also low as compared to others. The main Extension or displacement motion is achieved by the advantage of using hydraulic system in our application over application of force by hydraulic cylinder to one or more pneumatic other than the load bearing capacity is the fluid in supports. This force results in an elongation of the cross hydraulic system is basically incompressible, hence it leads pattern.
Retraction through hydraulic cylinder is also to minimum springing action. So even if the load on the achieved when lowering of platform is desired. This sort of safety measure is difficult to achieve This paper describes the design and analysis of hydraulic using pneumatic actuation, and even in case of uniform pallet system in a chain conveyor used in automobile loading the vibration encountered is much more.
Naik, et al conveyor, a pallet system is automatically controlled with A special type of beam lifting device is designed for textile the help of PLC. Our aim is to design a feasible and a cost industries. The machine is hydraulically operated and is effective mechanism to lift the given load using hydraulic having two frames one horizontal and another vertical. To check vibration of hydraulic lift during working time used for beam lifting to required height.
The mobility for the by modal analysis structure is provided by using castor wheels. Finite element 5. Scope of work: 1. Study of present design of Hydraulic lift. Identification and problem finding. The maximum stress is occurring when lift is at highest 3. Collection of input data from research work. Hence we did the analysis when weight is at 4. Study of weight-dimensional parameters highest point. General specification of lift is as follows when lift is at highest point. Study of stresses, deformations in lift 6.
Study of Vibration and impact resistance. Study of Keeping of service life at different loading 8. Study of Reliable operation b. Objectives: 1. Weight of the Present lift is high, Weight optimization is also prime objective of this project 3. For that we are going to consider arm AC only for calculation.
Build the FE model as explained in above chapter 2. Define the material properties such as young's modulus and density etc. Apply boundary condition and pressures.
Solve the problem using current LS command from the tool. Young s modulus 2. Poisson s Ratio 0. Density 7. Tensile yield strength Mpa 5. Hence Scissor Lift, mm. The amount of force required from the actuator is also amplified, and can result in very large forces required to begin lifting even a moderate amount of weight if the actuator is not in an optimal position. Actuator force is not constant, since the load factor decreases as a function of lift height. Types of lifts can be classified as follows:- Classification based on the type of energy used a Hydraulic lifts www.
A very brief analysis of each component follows thus: I. Scissors arms II. Hydraulic cylinder III. Top plat form IV. Base plat form V. Wheels Scissors Arms: this component is subjected to buckling load and bending load tending to break or cause bending of the components. Hence based on strength, stiffness, plasticity an hardness. A recommended material is stainless steel.
Hydraulic Cylinder: this component is considered as a strut with both ends pinned. It is subjected to direct compressive force which imposes a bending stress which may cause buckling of the component. It is also subjected to internal compressive pressure which generates circumferential and longitudinal stresses all around the wall thickness.
Hence necessary material property must include strength, ductility, toughness and hardness. The recommended material is mild steel. Top Platform: this component is subjected to the weight of the workman and his equipment, hence strength is required, the frame of the plat form is mild steel and the base is wood.
Base Platform: this component is subjected to the weight of the top plat form and the scissors arms. It is also responsible for the stability of the whole assembly, therefore strength.
Hardness and stiffness are needed mechanical properties. Mild steel is used. Considerations made during the design and fabrication of a single acting cylinder is as follows: a. Functionality of the design b. Manufacturability c. Economic availability. General cost of material and fabrication techniques employed Hydraulic cylinder: The hydraulic cylinder is mounted in inclined position. This mechanism provides a self-locking system which makes the scissor lift completely safe for use.
Unlike the hydraulic systems, this mechanism has to be driven to bring the platform back down. This gives us the opportunity to use this lift as a machine part for accurate elevation. We have calibrated the lift w. Hydraulic systems are used to control and transmit power. A pump driven by a prime mover such as an electric motor creates a flow of fluid, in which the pressure, direction and rate of flow are controlled by values.
An actuator is used to convert the energy of the fluid back into mechanical power. The amount of output power developed depends upon the flow rate, the pressure drop a cross the actuator and its overall efficiency.
Most lifting devices are powered by either electricity, pneumatic or mechanical means. Although these methods are efficient and satisfactory, they exist lots of limitations and complexity of design of such lifts as well as high cost of electricity, maintenance and repairs does not allow these lifts to exist in common places.
Considerations made during the design and fabrication of a s ingle acting cylinder is as follows: a. Functionality of the design. Economic availability. General cost of material and fabrication techniques employed Hydraulic cylinder: The hydraulic cylinder is mounted in inclined position. Now the maximum force will act on the cylinder when the cylinder is in shut down position i.
Forces at the end of link: as forces at ends of link are same in magnitude. Force at middle of link. In our case, the levels are numbered from the top. Above force will act on all the joints at end of each link. Design Analysis 1. But the piston rod diameter is rounded off to 32 mm in order to sustain buckling load. The piston head length is chosen based on piston seals to fox and width also no of seals to fix.
To check the piston rod for column action when a structure is subjected to compression it undergoes visibly large displacements transverse to t he load then it is said to buckle, for small lengths the process is elastic since the buckling displacements disappear when the load is removed. Base The base structure is built-up of C — channels and hollow bars are usually used in engineering applicati ons due to their high rigidity, 22 strength as compared to the other bars, the chosen C channel is ISMC Indian standard medium weight channel.
The supports and the two cylinders are flexibly coupled to the base there by not transmitting the full load on to the base. The total load on the platform and load kept on it is taken by the two cylinders and four supports which are made up of C — Channels. The extension or displacement motion is achieved by the application of force to one or more supports, resulting in an elongation of the cross pattern. The force applied to extend the scissors mechanism may by hydraulic, pneumatic or mechanical via a lead screw or rack and pinion system.
The name scissors lift originated from the ability of the device to open expand and close contract just like a scissors. Considering the need for this kind of mechanism, estimating as well the cost of expanding energy more that result gotten as well the maintenance etc. The initial idea of design considered was the design of a single hydraulic ram for heavy duty vehicles and putting it underneath, but this has limitations as to the height and stability, and someone will be beneath controlling it.
Therefore further research was made to see how to achieve this aim. Several challenges were encountered in this very design. Some amongst many include; low efficiency, risk of having the batteries discharged during an emergency, extended time of operation, dependent operation, as well as maintenance cost.
It is the consideration of these factors that initiated the idea of producing this hydraulically powered scissors lift with independent operator. The idea is geared towards producing a scissors lift using one hydraulic ram placed across flat, in between two cross frames and powered by a pump connected to a motor wheel may be powered by a pump generator.
Fig 3. A scissors lift does not go as high as a boom lift; it sacrifices heights for a large work station. Where more height is needed, a boom lift can be used. A scissor lift is a device used for lifting purposes, its objectives is to make the table adjustable to desirable height. A scissor lift provide the most economic dependable and versatile methods of lifting loads, it has few moving parts, which may only require lubrication. This lift table raises the load smoothly to any desired height.
In order to reduce the inadequacies of the devices mentioned above, a scissors mechanism is proposed. This mechanism is incorporated with a power screw and the top o f t he sc is sor s is att ach ed a t abl e pla tf orm. Thi s dev ic e wil l ma ke use of the pow er generated from a power screw to raise or lower a platform manually. Scissors Arms- Leg deflection due to bending is a result of stress, which is driven by total weight supported by the legs, scissors leg length, and available leg cross section.
The longer the scissors legs are, the more difficult it is to control bending under load. Increased leg strength via increased leg material height does improve resistance to deflection, but can create a potentially undesirable increased collapsed height of the lift. Also, as the scissors open during rising of the lift, the rollers roll back towards the platform hinges and create an increasingly unsupported, overhung portion of the platform assem bly.
Eccentric loads applied to this unsupported end of the platform can greatly impact bending of the platform.
Increased platform strength via increased support structure material height does improve resistance to deflection, but also contributes to an increased collapsed height of the lift. For those cases where the scissors lift is mounted to an elevated or portable frame, the base frame must be rigidly supported from beneath to support the point loading created by the two scissors leg rollers and the two scissors leg hinges.
Pinned Joints- Scissors lifts are pinned at all hinge points, and each pin has a running clearance between the O. The more scissors pairs, or pantographs, that are stacked on top of each other, the more pinned connections there are to accumulate movement, or deflection, when compressing these designed clearances.
Hydraulic Circuit — Fluid Compressibility- Oil or hydraulic fluid will compress slightly under pressure. And because there is an approximate ratio of lift travel to cylinder stroke for most scissors lift designs with the cylinders mounted horizontally in the legs , there is a resulting ratio of scissors lift compression to cylinder compression.
Hydraulic Circuit — Hose Swell- All high pressure, flexible hosing is susceptible to a degree of hose swell when the system pressure is incre ased. System pressure drops slightly because of this increased hose volume, and the scissors table compresses under load until the maximum system pressure is reestablished.
And, as with compressibility, the resulting lift movement is 5 times the change in oil column height in the hose. Cylinder Thrust- Resistance Cylinders lay nearly flat inside the scissors legs when the lift is fully lowered and must generate initial horizontal forces up to 10 times the amount of the load on the scissors lift due to the mechanical disadvantage of their lifting geometry.
As a result, there are tremendous stresses and resulting deflection placed on the scissors inner leg member s that are designed to resist these cylinder forces. Load Placements- Load placement also plays a large part in scissors lift deflection.
Offcentered loads because the scissors lift to deflect differently than with centered, or evenly distributed, loads. End loads inline with the scissors are usually shared well between the two scissors leg pairs. Side loads perpendicular to the scissors , however, are not shared well 27 between the scissors leg pairs and must be kept within acceptable design limits to prevent leg twist unequal scissors leg pair deflection — which often results in poor roller tracking, unequal axle pin wear, and misalignment of cylinder mounts.
Lift Elevations- during Transfer As mentioned above, degree of deflection is directly related to change in system pressure and change in component stress as a result of loading and unloading. Wheels Scissors Arms: this component is subjected to buckling load and bending load tending to break or cause bending of the components.
Hence based on strength, stiffness, plasticity and hardness. A recommended material is stainless steel. Hydraulic Cylinder: this component is considered as a strut with both ends pinned.
It is subjected to direct compressive force which imposes a bending stress which may cause buckling of the component. It is also subjected to internal compressive pressure which generates circumferential and longitudinal stresses all around the wall thickness. Hence necessary material property must include strength, ductility, toughness and hardness. The recommended material is mild steel. Top Platform: this component is subjected to the weight of the workman and his equipment, hence strength is required, the frame of the plat form is mild steel and the base is wood.
Base Platform: this component is subjected to the weight of the top plat form and the scissors arms. It is also responsible for the stability of the whole assembly, therefore strength. Hardness and stiffness are needed mechanical properties. Mild steel is used.
For example, the cost of materials in any machine is a good determinant of the cost of the machi8ne. More than the cost is the fact that materials are always a very decisive factor for a good design. The choice of the particular material for the machine depends on the particular purpose and the material for the machine depends on the particular purpose and the mode of operation of the machine components.
Also, it depends on the expected mode of failure of the components. Engineering materials are mainly classified as: Metal and their alloys, such as iron, steel, copper, aluminum etc. Non-metals such as glass, rubber, plastic etc. Ferrous metals are those metals which have iron as their main constituent, such as cast iron, wrought iron and steels.
Non-ferrous metals are those which have a metal other than iron as there main constituent, such as copper, aluminum, brass, tin, zinc etc. For the purpose of this project, based on the particular working conditions machine component were designed for only the ferrous metals have been considered. Also, certain mechanical properties of metals have greatly influenced our decisions. These properties include: Strength: it is the ability of a material to resist the externally applied force without break down or yielding the internal resistance offered without break down or yielding the internally applied force is called stress.
Stiffness: it is the ability of a material to resist deformation under stress. Elasticity: it is the property of a material to regain its original shape after deformation when the external force are removed.
Plasticity: it is property of a material which retains the deformation produced under load, permanently. Ductility: a very important property of the material enabling it to be drawn into wire with the application of a tensile force. A ductile material is both strong and plastic. Ductile materials 29 commonly used in engineering practical in order of diminishing ductility are mold steel, copper, aluminum, nickel, zinc tin and lead.
Malleability: it is a special case of ductility which permit materials to be rolled or hammered into thin sheets. A malleable material is plastic but not 80 essentially strong. Examples include; lead soft steel, wrought iron, wrought iron, copper and aluminum in order of diminishing malleability. Toughness: it is the property of a material to resist fracture due to high impact loads like hammer blows, when heated.
This property decreases. Brittleness: it is the properties of a material opposite to ductility, it is the property of breaking of a material with little permanent deformation when subjected to tensile load, brittle materials snap off without giving any sensible elongation. Cast iron is a brittle material. Hardness it embraces difference properties such as resistance to water, scr atching, deformation and machinability etc.
Mild steel can be rolled, wielded and down. It can even be cast, though not very successfully. Among its application are plates for ship building, bicycle frame tubes, mesh work, bolts, nuts, studs etc.
Stainless Steel: these are steel with high rust and corrosion resistance to meet specific application requirements.
They also have high strength and toughness. But first, a look at the operations and tools involved. Marking out Cutting Drilling Joining welding and bolt and nut Tools 1. Engineers rule 2. Scriber 3. Hack saw 4. Hand file 5. Drilling machine 6. Welding machine 7. Pliers 8. Try square Electric grinder 3. They are then joined together by welding to give the base frame.
It is usually made up of pipes with rectangular cross-section and have high resistance to bending. The material is stainless steel for corrosion and rust resistance to give high strength. After marking out, they were cut to the required sizes holes of appropriate diameter were drilled at both ends and the middle of each member. The scissors arms were brazed to increase the strength and bending resistance.
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