DESIGN AND MANUFACTURING OF FIXTURE FOR

LEVELING OF END CARRIAGE IN THE ASSEMBLY

OF END CARRIAGE-GIRDER

NIKHIL CHAVAN, ASHWINI DOSHI, PRITIBALA PEKHALE

UNDER THE GUIDENCE OF

PROF. S. S. PRABHUNE

ABSTRACT:

This paper consists of design and manufacture of fixture for the leveling of end carriage and

girder assembly which will be used to level the end carriage in the assembly of end carriage and

girder. The main aim is to design the system that will perform the leveling of the end carriage

using automation and which will be more efficient and user friendly.

The paper introduces several components used for manufacturing of mechanism. Properties of

different materials used for plates and their dimensions are discussed here. Use of mechanical

concepts and automation techniques is effectively used to increase the effectiveness and accuracy

of machining processes, which ultimately increases the productivity and replaces manpower.

INTRODUCTION: -

Generally on site assembly is preferred for crane assembly, as it is easy to transport the part of

the crane and assembly there than transporting the complete crane. Before the crane is dispatched

to the customer we have to make sure that it is properly leveled. The leveling of crane means the

end carriage and girder should be in one plane. This is achieved by leveling the end carriages.

The main aim of leveling is that the horizontal component of the load must be zero otherwise the

crane will be unstable to hold job at single location. In this leveling process end carriage and

girder are connected to each other through a bolted joint to MS plate is which is attached

between. This plate is already welded to the girder. End carriage and girder are assembled on the

site by bolting this plate to the end carriage. Due to this plate the end carriage and the girder both

are in same level and also all the four wheels of the end carriage is in one plane thus they rest on

leveled gantry and the horizontal component of the load is avoided.

Current procedure for leveling of the end carriage and girder assembly.

Main steps in end carriage girder assembly are as follows:

1. Place the girder on shop –floor.

2. Bolting the square plate to the end- carriage at the exact centre.

3. Placing the 2 end –carriages at both ends of the girder.

4. Match the centre lines of girder and both end- carriages.

5. Level the 2 wheels of one of the end-carriage.

6. With respect to these 2 wheels level the wheels of the other end-carriage. That is lifting

the lower sides by using ‘packaging plates’ till 0-0 level of all four wheels is achieved.

7. After the leveling is complete the plate is tac-welded to the girder.

8. Plate is then detached from the end-carriage, and the plate is properly welded to the

girder

Required specification of the fixture.

1. The fixture should be able to move the end carriage vertically from minimum height of

300mm to 1500mm.

2. The fixture should be able to accommodate the longest end carriage i.e. 4000mm long.

3. The fixture should be able to keep the end carriage holding in elevated position for long

periods.

4. The fixture should have provision for fine adjustment of end carriage for levelling.

5. The fixture should be easy to handle. No special skills are required.

WORKING MODEL:

In this arrangement the system rest on end carriages. On these end carriages the bottom

plate is bolted and on this plate pillars are mounted. The top plate is bolted on this arrangement

and lead screw is mounted on the arrangement and is given drive by motor. In this arrangement a

third pillar is added to the avoid sagging and to provide support for the system.

In this arrangement the load transfer is almost same as above arrangement

The load is placed on the plate which is welded to the box and given drive by motor and

screw. The motor and screw are mounted on top plate. This top plate is rested on pillars. Thus

the load transfers from screw to the top plate and though the plate to pillars and to the ground.

The salient features of this arrangement are

i. In this arrangement the toppling problem is avoided by shifting the load from corner

to the centre.

ii. We have provided the mechanical jacks for the fine adjustments, thus removing the

limitation of spring compression.

iii. The dead weight is not required as the system is stable for toppling

iv. A third pillar is added at the centre which avoid the sagging problem.

Thus this system covers almost all the problems, hence this solution was finalized.

THE MATERIALS SELECTION PROCESS

1. EN-8

PROPERTIES:-

C 40A %C 0.35-0.45, %Mn 0.60-0.90

TENSILE STRENGTH:-580-680, YEILD STRENGTH:-330

USES:-

Steel for crankshafts, spindles, shafts, automobile axle beams, push rods, connecting rods, studs,

bolts, lightly stressed gears, etc.

2. MILD STEEL

PROPERTIES:-C15 MN75 (%C:- 0.10 - 0.20,%Mn:- 0.60 - 0.90)

TENSILE STRENGTH:- 420 – 500, YEILD STRENGTH:- 250

USES:-

Especially desirable for construction purposes due to weld ability and machine ability.

PHOSPHOR BRONZE

PROPERTIES :- %COPPER:- 87 – 90 ,%Tin:- 9 – 10 ,%PHOSPHORUS:- 0.1 – 3

TENSILE STRENGTH:- 215 – 280

Possesses good wearing qualities and high elasticity. Resistant to salt water corrosion.

USES:-

Used for bearing, worm wheel, gears, nuts, lead screw, pump parts, etc.

CALCULATIONS

TORQUE RQUIRED TO RAISE THE LOAD

T=67844.85 N-mm

Now for DIAMETER OF SCREW

Consider stresses in lead screw

1. Tensile Stress (Direct) :-

2. Torsional Shear Stress: -

3. According To Maximum Shear Stress Theory

=

Solving above equation we have

= 21MM

Hence minimum required diameter is 21mm. But as it was not available in market, we choose the

one with

= 46MM

Hence the properties of screw are

D = 50MM

DC = 41.5MM

DM = 46MM

P = 8MM

FOR NUMBER OF THREADS IN CONTACT

Let the permissible bearing pressure be 5N/mm2

OR 7

Number of threads in contact Z= 7

Height of nut H = Z×P

= 7×8

= 56MM

FOR POWER REQUIREMENT

As we have selected motor with specification as follows

Power = 0.37KW

Speed N = 1370RPM

As motor is fixed, calculate for reduction required

Assuming no power loss

Power @screw P = 0.37KW

Torque T = 67.844 N.m

here ω is angular speed of the screw and is given by

Ω = × ×N’/ 0

Hence reduction required

G= 26.

Now as we have the gear box with reduction of 9 in stock.

I.E. Gg=9

Thus the reduction required is

Gs=G/Gg

PARAMETER NOTATION VALUES

FOR SCREW BODY

MAJOR DIAMETER D 50mm

PITCH CIRCLE DIAMETER Dm 46mm

CORE DIAMETER Dc 41.5mm

CORE AREA Ac 1353mm2

PITCH p 8mm

HEIGHT OF THREAD H 4.25mm

COEFFICIENT OF FRICTION µ 0.08

ANGLE OF THREAD Β 30˚

EFFECTIVE COEFFICIENT OF

FRICTION

µ’ 0.09

LEAD ANGLE Α 3.168˚

FRICTION ANGLE Φ 5.227˚

TENSILE STRENGTH Sst 450N/mm2

YEILD STRENGTH Ssy 250N/mm2

FACTOR OF SAFETY Nf 5

FOR NUT

HIEGHT OF NUT H 56mm

DIAMETER Dn 50mm

NO. OF THREADS IN CONTACT Z 7

FOR MOTOR

POWER RATING P 0.37KW

RPM N 1370rpm

FOR CHAIN DRIVE

FOR PINION

NO OF TEETH NP 15

PITCH CIRCLE DIAMETER DP 61.08MM

CORE DIAMETER DPC 45MM

WIDTH OF PINION BP 35MM

BORE DP 10MM

FOR SPROCKET

NO OF TEETH NS 45

PITCH CIRCLE DIAMETER DS 182.06

11.1 .Comparison between the current procedure and new procedure.

11.1.1. Current Procedure

Criteria value (FOR

CURRENT

PROCEDURE)

Values(FOR NEW

PROCEDUR)

No. of laborers 4-5 1-2

Time for single girder

assembly

2-3 hrs 20 – 30 min

Time for double

girder assembly

5-6 hrs 30-40 min

Wages Average Rs 30/hr.

SG –RS 360/-

DG- Rs 720/-

Rs 30/hr

SG- Rs 30 /-

DG- Rs 40/-

CORE DIAMETER DSC 95MM

WIDTH OF SPROCKET BS 40MM

BORE DS 20MM

FOR CHAIN ISO NO- 08B-2

PITCH PC 12.07MM

ROLLER DIAMETER D1 8.51MM

WIDTH B1 7.75MM

BREAKING LOAD F 31,000N

11.2. Calculations

1. Average Number of cranes manufactured per month: - 11

Single girder: - 7

Double girder: - 4

2. Amount saved per cranes: -

Single girder crane: - Rs 330/crane

Double girder crane: - Rs 680/crane

3. Total amount saved per month: -

Single girder crane: - Rs 330×7= Rs2, 310

Double girder crane: - Rs 680×4= Rs 2,720

Total = Rs 5,030

4. Annual saving: - Rs 5,030×12= Rs 60,360

5. Total investment: - Rs 2, 12,352

No of years = Rs 2, 12,352/60,360

= 3.5 years.

12.1. CONCLUSION: -

We have designed and manufactured a fixture for leveling of end carriage in the assembly

of - girder and end carriage - of EOT crane.

Thus we have improved the current procedure of leveling and we have achieved

following things

1. It requires 4-5 workmen for a single job for the current procedure but now we require only

one or two persons.

2. The current procedure is not sufficiently safe as it includes the handling of the end carriages

using hooks of crane while in new procedure end carriage is rested on plate thus new

procedure is safer.

3. It takes 4-5 hours for the levelling by current procedure but now it takes only 20 – 30

minutes.

4. Accuracy is less of the current procedure but the new procedure is more accurate.

5. The current procedure requires skilled workmen but the levelling by new method can be

done by unskilled worker also.

13.1. FUTURE SCOPE: -

We can provide the arrangement for the horizontal movement by giving drive to the base end

carriages.

1. Limit switches can be provided to the fixture to restrict the maximum vertical movement

of the fixture.

2. Total levelling process can be automated with the help of programmed PLC panel using

LASER level indicators for auto levelling.

3. The fine adjustment can be achieved by motor instead of screw jack controlled by PLC

panel this will convert the total system into automated system reducing the human efforts.