Automation is the integration of mechanical, computer electronic based activities the control of manufacturing processes in the field of production. Different techniques of automation are carried using pneumatic, hydraulic system, cam follower computer system.
In this project of automation of burr cleaning process, I have selected and implemented the pneumatic technique of automation. For automation, I have designed manufactured air blowing machine, which is operated with the help of pneumatic system controlled by PLC. In this mechanism the DLL nozzle is run over the guide way clamp by pneumatic cylinder. Then the air pressure of 5 bars is supplied to the tip of nozzle through jet which cleans the burr form nozzle ball end. I assembled air blowing machine with pneumatic cylinders for clamping, unclamping, supporting individualizing purpose, proximity sensor other necessary components.
In this automation of air blowing machine I studied different types of machining processes, pneumatic system, and PLC system. After automation of air blowing machine the working stress on operator is reduced the production rate is substantially increased with improvement in quality of burr cleaning process.
Chapter 1 : Introduction
This project identifies and describes the automation process used to clean and deburr the nozzle which is present in fuel injection system, through the working of Air blowing machine. Air blowing machine uses different concepts of automation such as pneumatic, hydraulics, cam-follower etc. The main function of this machine is to control manufacturing process in production.
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1.1.Background
Nozzle is one of the vital component in any fuel injection system which is attached to the nozzle holder. It is integral and important part of an injector which regulates the flow of fuel to the ultimate ignition compartment.. According to Sean Bennet all Diesel engines (DI) are directly injected. The fuel is injected into the cylinder immediately above the piston. Atomization is necessary for the injected fuel. Atomization of the fuel requires breaking it up into very small liquid droplets. These droplets are produced by forcing very high high-pressure fuel through minutely sized orifices or holes. The smaller the droplets, the faster it will vaporize and ignite when it is propelled into the engine cylinder. The size of droplets that exits the injector depends on following factors :
Size of Orifice: The diameter of the orifice determines the size and flow of in the system. It does not change after it has been manufactured.
Pressure :Injection pumps manages the pressure in nozzles. The higher the pressure, the smaller the droplets exiting the nozzle.
The means to inject the fuel into the cylinder is an injector nozzle. Injector are further subdivided in two types with respect of an electronically controlled pump and injector components :
Multiple-orifice hydraulics nozzles.
Electrohydraulic nozzles.
Injector nozzles are mostly used in diesel engines, marine engines, locomotives and automobile industrial equipments .The main function of nozzle is to convert the diesel into diesel vapours and spray it on the piston. Injector nozzles are widely used in American tanks.
Figure 1.1 External view of injector/orifii nozzle
(Courtesy of Robert Bosch GmbH,www.bosch-presse.de)
The main users of nozzles are Nissan, Mitsubishi while Bosch is one of the leading manufacturers of these nozzles .Manufacturing process of this nozzle is carried through several operations after case hardening. These operations are drilling, grinding and pinning of the orifice. After the compete process of pinning, it is found that some metal particles and burr is remained at the orfii. In order to eliminate this particle nozzle testing machine is required to test the nozzle.
1.2 Issue :
Air blowing operation is carried by an operator with the help of cylinder or jet directly attached to compressed air supply. To serve this purpose operator clamps the whole tray full of nozzles and then he reverse it. This gives more fatigue and stress to the operator because of its heavy weight. Then jet is placed on the ball end of nozzle and part gets clean. One part is been cleaned at a time.
Furthermore, since inside of the nozzle body function as passage to the fuel ,if any chip or burr generated in cutting process remain on the nozzle body, it enters into the contact surface of the valve element and causes malfunction and fuel spillage of the valve element, which result into the loss of product reliability.
The aim of the task is to make air blowing operation which is done after pinning to remove burr present inside the nozzle automatic and reliable, so the stress on operator is reduced with control manufacturing system.
1.3. Objectives :
The main objectives of the project are stated as follows:
To study and implement the pneumatic technique of automation for the successful working of the machine.
To design and develop Air blowing machine which will be used in manufacturing and cleaning process of nozzle present in the fuel injection system.
After the Research of Diesel Engine from Books and internet it is found that nozzle is one of the important part in fuel injection system. Nozzle development led to study the manufacturing processes of nozzle. Bosch company are the leading producers and patent of the diesel engine stated by Rudolf Diesel. In the general manufacturing process of nozzle after the case hardening, drilling, ball-grinding and pinning are important operation for the processing of the nozzle. However it is found out that during this operation burr or free metal particle gets collected inside the nozzle body.
Introduction of Air blowing machine :
To remove this burr or free metal particle Air blowing machine is introduced for the improved performance of the nozzle.
Draft Design and 3d model:
In order to build a successful Air blowing machine, design is very important to generate the safe and working model. Selection of materials, shape, parameters is the important factors to develop a 3D model of machine. Software’s like solid works, CES and some hand calculation is useful for the correct and accurate 3D draft design.
Analysis and Results :
After the complete design process of the machine the next and important stage is the mechatronic analysis. Pneuamatic and Electronics (PLC circuit ) techniques are used for the successful and automatic working of the machine. If these techniques are successful then go to the next stage or else go back and recheck the 3D model again. After the analysis, results indicates the final consequence for the actions of the work. Validation of results gives the reality check of the project. If the validation is true then follow the next stage and conclude the project with the useful recommendations.
Chapter three : Literature Review
3.1 Patent and Research :
Bosch group is one of the leading manufacturers of these nozzles and equipment for motor vehicle.
In early as 1863, the Frenchman Etienne Lenoir had tested and driven a vehicle which was powered by a gas engine which he had developed. However, this vehicle proved insufficient for installing in and driving. It was not until Nikolaus August Otto’s four-stroke engine with magneto ignition that operation with liquid fuel and thereby mobile application were made possible. But the efficiency of these engines was low. Rudolf Diesel then developed an engine with much higher efficiency and to pursue his idea through higher efficiency and to pursue his idea through manufacturing.
In 1897, in cooperation with Machinenfabrik Augsburg-Nurnberg ,Rudol Diesel built the first working prototype of a combustion engine to be run on inexpensive fuel oil. However due to heavy weight of the engine, it wasw not considered for use in land vehicle. But with further improvements in fuel injecton and mixture formation, Diesel’s innovation caught on and there were no longer any viable alternatives for marine and fixed-installation engines.(Adopted from Robert Bosch Gmbh, DIESEL-Engine Management by Wiley 4t edition et al 2005)
In 1886,Robert Bosch (1861-1942), introduced a workshop for electrical and mechanical engineers in Stuttgart, Germany. Later on in 1897 Bosch opened ignition system in gasoline engines. In 1922,Robert Bosch turned his attention to diesel engine and hence started manufacturing accessory parts such as nozzles and fuel injection pumps. Rudolf diesel wanted to inject the fuel directly earlier in the system, but was unable to do this because of unavailability of the nozzles and fuel-injection pumps. In contrary these pumps were used in compressed-air injection, had to be suitable for back pressure reactions of up to several different atmospheres. Nozzles had to have quite fine outlet openings because the task fell upon the pump and nozzle is increased to atomize the fuel. Hence in 1922 Bosch wanted to develop the nozzles and fuel-injection pumps that fulfils the requirement of all the heavy-oil low power engines with direct fuel injection.
3.2 Development of the system :
The demand of fuel injection equipment on such that it should be a capable of injecting even small amounts of fuel with only quite small differences, so that it should facilitate more smoother and constant at low idle speeds. The performance of this system depends highly on injection pressure which should be average or above 100 bar. The operating hours of the pump was over 2000 according to Bosch. Hence the need to develop the related equipments had grown immensely with application of materials and production engineering. In 1925, Bosch joined hands with Acro AG to utilize the Acro patents on a diesel engine system with related injected equipments(nozzle). Acro injection properties did not matched, Bosch’s own test system but it offered diesel engine which was suitable for small cylinder units and high speeds and this led Bosch to develop nozzle and fuel injection pump. Sooner the first diesel fuel-injection pump by Bosch was produced
Nozzle were developed parallel to pump development. Hole type nozzle were added later after the introduction of pintle nozzle. The nozzle were adapted with their process and size. Engineering manufacturers also wanted a nozzle which could be used in spark plug on a gasoline engine.
3.3 Expert View :
3.4 Scope of improvement:
Diesel fuel injection has greater degree of features in world of technology. The needle valve in fuel injection system opens and close nozzle more than million times in the service life of nozzle. It generates and provides pressure as high as 2,050 bar and depends on stresses such as:
Temperature and pressure of the combustion chamber .
Shock caused by continuous opening and closing.
High flow related stresses during fuel injection.
Below are the features of the nozzle and its processes:
Injection duration is 1-2 milliseconds which is higher compare to sound wave from loudspeaker .
Pressure in the fuel-injection chamber is more than 2,050 bar and it operates efficiently at such a high pressure.
Injection duration in vehicle varies from very low range to high range,hence the amount of fuel is forced at very high velocity through a very small opening.
The clearance of valve needle is 0.002 mm which is very minimal.
Hence high technology demands an enormous amount of expertise in development, materials and manufacturing techniques.
3.2 Current stage :
Processes on nozzle :
During the manufacturing process when part is about to go through final processses,case hardeniing is done on it.
After case hardening, part goes through two operation as folllows :
Drilling of the Orifice
Ball Grinding at ball end from outer surface.
When nozzle comes out for drilling, it is first hardened. Then the orifice is
drilled at the ball end. According to the requirement the number of orifice
varies from 3-8.The diameter of orifice is within 0.3-0.4 mm.DLL nozzles
are further classified in many types with number of orifice.
Fig1.2:Orifice drilled at ball end
Then the part is brought to grinding station, where part goes through outer grinding at the ball end.
Fig 1. Grinding at ball end after drilling
A metal burr is remained at the entrance of the orifice due to the grinding. This metal burr reduces the performance of the nozzle. Hence it is necessary to remove this burr .To serve this burr, pinning operation is done on nozzle so that burr gets removed.
Fig:1.4 Metal burr remain at ball end due to grinding
Pinning :- Pinning is the operation in which a needle having comparatively smaller diameter than orifice is attached to the small motor having speed of 300 rpm.This needle is then inserted in the orifice.Due to this the burr is removed and gets collected inside the nozzle at the ball end.
These free metal particles reduces the performance of nozzle or can damage the nozzle inside the body.Its not an easy task to remove this free metal particle.An air pressure of 5-10 bar is blown inside the nozzle from ball end to come out from other end of the nozzle as shown in below figure
Fig 1.5 Air blowing through orifice to remove free metal particle
Chapter 4 : Design
Introduction of Air Blowing Machine
Fig: Air Blowing Machine
4.1 Introduction of Air Blowing Machine
It is the machine used to remove the free metal particles present inside the nozzle body. The main function of this machine is to remove this free metal. To remove this metal air is been blown inside the nozzle at 5bar pressure. Pneumatic circuit is attached to the machine and it is controlled by PLC. Hence it is based on mechatronics. Mechatronics is the branch of engineering which is defined as the combination of mechanical and electronics engineering to improve quality, productivity and effective utilization of energy.
Pneumatics deals with usage of compressed air to create motion and hence can be utilised for doing useful work. Certain characteristics of compressed air have made this medium suitable for the use in modern manufacturing and production plants. Introduction of pneumatics in the manufacturing process benefited with cheaper medium of industrial automation which if judiciously used, may bring down the cost of production to much lower level. Many mechanical task that came across can be achieved pneumatically in nozzle manufacturing process.
4.2 Material
Selection of Materials :
Material should be softer than Nozzle material.
The optimum material is Mild Steel according to CES software
Properties of mild steel (C3O) :
Carbon percentage = 0.3%
Modulus of Elasticity= 2.06×105 N/mm²
Modulus of Rigidity = 0.79×105 N/mm²
Poisson’s Ratio = 0.3
Tensile Strength = 600 to 750 N/mm²
Yield Strength = 400 N/mm²
Izod Impact Value = 55Nm
Density = 7.78×10
4.3 Hand -Calculation for Design :
Angle of Inclination for the Guide way :
Fig : Forces on Nozzle
Data Found :
Mass of nozzle = 200gm
Co-efficient of friction = 8 %
Weight (w) = 0.20 – 9.81 = 1.962 N
Let,
R= Reaction force.
Ψ = Angle of contact
Addition of forces in horizontal direction is zero.
Hence,
ΣFx = 0
R = w cos Ψ………………….. 1
Addition of forces in vertical direction is also zero.
Hence,
ΣFy = 0
μR = w sin Ψ………………2
Now by dividing equation 2 by 1 we get,
μ = tan Ψ
0.08 = tan Ψ
Ψ = 4.573Ëš
Therefore,
Ψ = 5Ëš
To find reaction,
From equation 1,
R = w cos Ψ
R = 1.962 – cos (5)
R = 1.9543
Factor of safety for design :
Design of Cylinder holder : 1
Fig : Cylinder holder for cylinder
Air pressure = 5 bar
Force by the cylinder = 245 N………….(Reference solid works )
Hence,
Bending moment = Force x Displacement
= 245 x 36
= 8820 N-mm
Static load through stress,
Volume of the holder = 40×42 x15 +15 x15 x71 x40
= 67.8 x 10³ mm³
Mass = Density x Volume
= 7.78 x10-6 x 67.8 x 10³
= 0.5278 Kg
Weight (P1) = mass x gravitational acceleration
= 0.5278 x 9.81
= 5.1746 N
Total weight (P) = Wt. of element + Wt. of cylinder
= 5.1746 + 0.5×9.81
= 10.0746 N
Stresses at the joint (σ) = P ÷ A
= 10.0746 ÷ 65×15
= 10.338 – 10-3 N/mm²
Extension in the element (σst) = (σ ÷ E) x L
= (10.338×10-3 ÷ 2.06x 105) x 35
= 1.756 x 10-6 mm
Maximum Impact load acting on the bolt (Pmax) = P {1+√ [(2 h) ÷ σst ] }
= 10.0746 {1+ √ [(2 x 50) ÷ 1.756 x 10-6]}
= 76.06 x 10³N
Stress produce due to Impact load (σp) =√ [(2 E P h) ÷ (AL)]
= √ [(2x 2.06x 105 x (10.1746+245) x 50) ÷ (65×15 x 35)]
= 392.47 N/mm²
392.47 N/mm² < 600 N/mm
Stress produce due to impact load less than 600 N/mm hence design is safe.
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