Compressors and Application
Compressor : Compressor is basically used for increasing the pressure of a fluid by compressing compressing the fluid fluid in a closed chamber for compressible fluids OR by imparting Kinetic energy in it and subsequently changing Kinetic Energy into Pressure Pressure Energy for incompressible fluids. fluids. Types of Compressors : The compressors are classified as follows. Depending on the construction : • • •
Hermetically sealed compressors Semi sealed compressors Open type compressors
Depending upon working principle principle : • • • •
Reciprocating compressors Rotary compressors Screw compressors Scroll compressors
Hermetic Compressor : When the motor, the gas pump assembly and other parts are placed in side the dome OR housing and completely sealed , is called Hermetic Compressor. Application of Hermetic Compressors : Hermetic Hermetic Compressors Compressors are generally generally used in the Refrigerators Refrigerators , Air - Conditioner Conditionerss , Water coolers coolers and Chillers. Genera Generall lly y Recipr Reciprocat ocating ing compre compresso ssors rs are used used in Refrig Refrigera erator torss and Rotary Rotary compre compresso ssors rs are in Air conditioners. Role of the compressor in the Refrigerator / Air conditioner / Water cooler / Chiller Chiller is vital and the entire functioning and efficiency of the system depends on the working and efficiency of the Compressor. Cost of the compressor is around 50 % of the Refrigerator / Air -Conditioner / Water cooler / Chiller. Hence the Compressor is the heart of the system / product. Function of compressor in Refrigeration : •
•
Elevat Elevating ing the tempera temperatur turee of the refriger refrigerant ant gas and pressu pressure re to such such values values at which which the vapor vapor refrigerant change its phase from vapor to liquid at room temperature. Returning the evaporated liquid from the evaporator maintaining the mass flow of the gas in the system. 1
Importance of Refrigeration : There are few phases of modern living untouched by refrigeration and air conditioning. business operations, manufacturing processes, storage, and shipping are almost always carried out today under controlled temperature conditions. The refrigeration and air conditioning industry helps make possible this system system of living. Air Air conditioning has improved business and industrial efficiency, while adding to h uman comfort . More and more factories and heavy industries are being
air conditioned.
Many fruits and vegetables are refrigerated immediately upon being harvested the quality of such products is much better for this reason. Cooling and freezing of meat and meat products makes possible their handling sanitary way than would be possible without mechanical refrigeration. Beverages, desserts , and even staple foods are all at least equipment.
partially processed by
in a much
refrigeration
Who's who in refrigerator industry: • • • • • • • • •
GE Whirlpool Electrolux Maytag LG Samsung Matsusitha / Panasonic Haier Kelon
Refrigerator demand in India : •
Estimated Sale for 2003 - 2004 is
3.4 Mln - 3.65 Mln units.
•
Almost 60% of sales are in from refrigerators priced between Rs 12,000 - Rs 16,000.
•
The 165 - 225 litre segment comprises 75% of the total demand.
•
Expected growth rate at 10-15% for 2004 - 2005.
•
Expected growth in 2004 - 2005 is
•
Average growth rate from 1999 is 5%
4.1 Mln - 4.2 Mln units.
Future Trends of Refrigerator : Fuzzy logic • 2
• • • •
Power Saving Freshness Coolness User Friendly
Who's who in compressor industry : The three largest manufacturers over 15 Million annual production are: Matsushita (Malaysia, Japan, Korea) • Electrolux (Italy, Austria, Austria, Spain, US, China, Egypt, India) • Whirlpool (Brazil, Italy, China, China, France) • Tecumseh ( USA ) • World Compressor demand : The installed capacity of Compressor Manufacturers is 80 Million Actual Annual production is 65 Million
Compressor demand in India : Installed capacities is 8.1 Million whereas actual production is around • 3 Million Technology changes : • • • • •
Environmental Friendly Technology Low Energy Consumption Low Noise Level Very Compact size High Efficiency
Basic principle princ iple of Refrige Ref rigerat ration ion : The simplest form of a vapor compression system is an open vessel containing any liquid which has a boiling point well below surrounding space temperature. The liquid picks up heat ( latent heat ) required for its change of phase from liquid to vapor. And lowers the temperature of the vessel wall and surrounding air. This method of refrigeration is uneconomical since the recovery of evaporating liquid is not possible. Therefore an economical refrigeration system must consists of a method of refrigerant recovery back into the form of liquid for continuous evaporation. In all the refrigerant systems, the process of evaporation take place in the evaporator and the conversion of vapor to liquid achieved by the compressor and condenser. Function of compressor : •
•
Elevat Elevating ing the tempera temperatur turee of the refriger refrigerant ant gas and pressu pressure re to such such values values at which which the vapor vapor refrigerant change its phase from vapor to liquid at room temperature. Returning the evaporated liquid from the evaporator maintaining the mass flow of the gas in the system.
Function of condenser : 3
The condenser aids the recovery by receiving the refrigerant at high pressure and high temperature and lowers it temperature up to the condensing temperature for converting it to liquid dissipating the heat to the surrounding atmosphere. Expansion device ( Capillary tube ) : The main main functi function on of a capilla capillary ry tube tube is to reduce reduce the temper temperatu ature re of refrig refrigera erant nt from from condens condensing ing temperature to below evaporate temperature ( by the principle of cooling and throttling ) to enable heat removal from evaporator. Capillary divides the system into a high side and low side. The low side is for lowering the boiling point of the refrigerant below the conditioned space temperature and the high side for conversion of vapor to liquid. Another function of the capillary tube in a system is to meter the flow of refrigerant at the same rate as of its evaporation in the evaporator. Refrigerant : Refrigerant are heat carrying mediums which during their cycle in the refrigeration system absorb heat at low temperature level and discard the heat so absorbed at a higher temperature. Refrigerants have boiling points much below ordinary room temperature and so they exist as gases and are only held as liquids by keeping them under pressure, such as in a refrigerant cylinder. Types of Refrigeration : Refrigerat Refrigerator or is basically basically a reversibl reversiblee heat engine. It follows the theoretical theoretical 'Carnot' cycle. cycle. 'Carnot' 'Carnot' cycle comprises of two ' Isotherm ' processes and two 'Adiabatic ' processes. Different techniques are practiced to achieve this. They are Vapor compression refrigeration. • Vapor absorption refrigeration. • The most common type used in household refrigeration is Vapour Compression Refrigeration .The two isotherms of ' Carnot ' cycle are the two heat exchange process, viz. Condensation and Evaporation and two Adiabatic are throttling valve expansion and compression by Compressor. In Isotherm process, the system temperature is always constant but pressure varies. In Adiabatic process , the pressure is always constant but Temperature varies. Vapor compression refrigeration cycle : As the refrigerant circulates through a vapor compression refrigeration system , it passes through a number of changes in state or condition in a definite sequence and returns to the initial condition to complete a cycle. cycle. This This cycle cycle is made made up of fundam fundament ental al proces processes ses viz. viz. Expans Expansion ion,, vaporiz vaporizati ation, on, compre compressi ssion, on, condensation. Vapor compression refrigeration circuit diagram is shown in the next page. Thus, the vapor compression refrigeration system can briefed as follows: (1)– (2) Adiabatic compression by a reciprocating compressor. (2) - (3) Condensation. (3) - (4) Throttle and expansion. 4
(4) - (1) Evaporation. So, compressor is the heart of refrigerator. It takes the refrigerant vapor at low pressure low temperature and delivers it at high pressure high temperature. By taking up the refrigerant vapor from evaporator, it also maintains the flow in the refrigeration circuit. The performance of a compressor is measured by C.O.P value and it varies from 3.1 to 5.4 BTU / Watt Hr. C.O.P is co-efficient of performance. For a refrigerator it is defined as the ratio of refrigerating effect obtained and compressor work input to the system. E.E.R – Energy efficiency ratio. Range of Compressors : Based on the capacities the compressors are categorised into Low back pressure, Medium and High back pressures. The L.B.P range varies from 98 to 1 48 Kcal/Hr. The M.B.P ranges from 148 to 300 Kcal/Hr. The H.B.P ranges from 340 Kcal/Hr and above. Ton of Refrigeration : The method for rating refrigeration equipment goes back to the days when ice was used as the source for removing heat. One Ton of refrigeration is (2000 lbs.) of ice in a 24 hour period.
the
amount
of
heat
required
to
melt
1
ton
It takes 144 Btu of heat to melt 1 pound of ice. It would take 2000 times that much heat to melt a ton of ice. 144 Btu / lb X 2000 lb = 288,000 Btu / 24 hours 12,000 Btu / Hour = 1 Ton Types Refrigerants : Refrigerants commonly used today are classified into four areas : Chlorofluorocarbons -- CFC • Hydrochlorofluorocarbons -- HCFC • Hydrofluorocarbons -- HFC • Refrigerant blends. • Properties of Refrigerants : • • • • • • •
It must follow the standards set by environmental protection agency. It should be nontoxic. It should be non explosive. It should be non corrosive it should be nonflammable. It should make leaks easy to detect and locate. It should operate under low pressure. 5
• • • •
It should be a stable gas. It should permit refrigerator or compressor parts moving in the fluid to be easily lubricated. It should have high liquid volume per pound to provide durable refrigerant controls. It should have a low vapor volume per pound. It should have high latent heat.
CFC Refrigerants : These refrigerants are composed of Chlorine, Fluorine, and Carbon and are called Chlorofluorocarbons. Common CFCs are R-11 • R-12 • R-113 • R-114 • R-115 • These are one of the major cause of ozone depletion. HCFC Refrigerants : These are composed of Methane or Ethane in combination with Halogens. the common HCFCs are • •
R-22 R-123
HFC refrigerants : This contains one or more hydrogen atoms and no chlorine atoms. Common HFCs are • •
R-134a. R-124.
Refrigerant blends : There are two two types of blends : •
Azeotropic blend 1. Zeot Zeotro ropi picc blen blend. d.
•
R600a R290
•
Ozone layer : The ozone ozone layer layer is a fairl fairly y thin thin layer layer of the earth‘ earth‘ss upper upper atmosp atmospher heree .(stra .(stratos tospher pheree ) it is approximately thirty five miles above the ground. The ozone layer functions as a filter for the sun‘ s ultra violet rays .This protects human, plant, and sea life from the damaging effects of sun .
6
Scientists have found that releasing Chlorofloro carbons ( cfc ) from refrigerants can harm the ozone layer . the chlorene content content in in the the cfc cfc is the cause for for depletion of ozone layer. layer. This concern concern has developed into what we refer as the EPA ( Environment Environmental al Protection Protection Agency ) regulations. these regulations identify types of refrigerants that can be produced and used. and define define the phase out program program of these cfcs. Countries Countries through through out the world have passed passed legislation preventing the use of chemicals chemicals that effect this layer layer . Ozone Depleting potential : This measures the capacity of the refrigerant to destroy the ozone layer by reacting with the ozone gas. Global warming potential : This measures the capacity of the refrigerant to cause global warming. Montreal protocol : Montreal protocal on substances that deplete the ozone layer was agreed to on september 16, 1987. the montreal montreal protocal protocal obligates obligates all parties parties to phase out ozone depleting depleting substances substances according to a specified time table and was so designed that the phase out schedules could be revised on the basis of periodic scientific and technological assessments. As per Montreal protocol provisions for article 5 countries, the Indian industries have to phase out the production and / or use of Ozone depleting substances by the year 2010. Earth's outer atmosphere is having a thick layer of ozone gas, which protects us from different ultra violet and cosmic rays. It has been found that in some areas this ozone layer is being depleted because of many reasons, use of CFCs is one of them. Chlorine of CFC reacts with ozone and thus destroys the ozone layer. Thus for refrigerator industry, the immediate alternative for R12 is R134a which is Hydrofluoro carbon ( HFC ). As there is no chlorine atom, hence it does not react with ozone. But this changeover requires a lot of change in system design and manufacturing of refrigerator. These change overs can be listed as follows :•
Displacement of Compressors.
•
Changes to counter the flammable nature of gases used.
•
High degree of cleanliness and process for removal of contaminants.
•
High degree of moisture removal by Dehydration and Evacuation system. Changes in the material used like Mineral oils, coating and insulation of wires.
•
•
More use of Aqua / Alkali cleaning agents. Manufacturing of Hermetic Compressors
Compressor :
7
Compressors are basically used for increasing the pressure of a fluid by compressing the fluid in a closed chamber for compressible fluids OR by imparting Kinetic energy in it and subsequently changing Kinetic Energy into Pressure Energy for incompressible fluids. Types of Compressors : The compressors are classified as follows. 1. Depending on the construction : • • •
Hermetically sealed compressors Semi sealed compressors Open type compressors
Hermetically sealed compressors : When the motor and the compressor are placed in side the dome OR Housing and completely sealed, is called Hermetic Compressor. 2. Depending upon it's working principle : • • • •
Reciprocating compressors Rotary compressors Screw compressors Scroll compressors
Among these types the most common type of compressor used for Refrigeration is Reciprocating compressor. Working principle of Reciprocating Compressor : Basica Basically lly,, this this type type of compre compresso ssorr belongs belongs to the positi positive ve displa displaceme cement nt class class machin machines. es. General Generally ly reciprocating compressors are driven by means of a electric motor. The rotary motion is converted into reciprocating motion by means of Slider -Crank mechanism. (i.e. (i.e. Piston - Connecting rod-Crank rod-Crank shaft ). Reciprocating compressors works on '' Brayton cycle '' , in which one cycle completes in each 360 degrees of crank rotation. Thus there are two strokes in each cycle. ( i.e Suction and Compression ). During downward movement of piston, the refrigerant vapour is taken in through suction line via intake valve. During upward movement, vapour is compressed and passed through a small diameter pipe and subsequently through expansion valve. Gas pump Assembly : Gas pump assembly is a critical part of the compressor which facilitates the function of pumping the refri refriger gerant ant gas for circul circulati ating ng in the closed closed loop loop cycle cycle of refrig refrigera eratio tion. n. The refrig refrigera erant nt has to be in continuous circulation in the system at different temperatures and pressure to complete the refrigeration 8
cycle. This is achieved by continuous compression and pumping of the same with the help of gas pump assembly. The gas pump assembly consists of the following components: • • • •
Compressor block Piston Connecting Rod Piston pin
The piston operates in a reciprocating motion in the cylinder bore, which is an integral part of the compressor block. The connecting rod which is connected to crank shaft - upper bearing- rotor group , helps in transmitti transmitting ng the rotary motion generated generated by stator & rotor, into the reciprocati reciprocating ng motion of the piston. piston. By the reciprocating reciprocating motion of the piston, it sucks refrigerant refrigerant gas into the cylinder and pumps the same into the system after compression. The refrigerant gas is sucked into the pump assembly through suction muffler assembly, valve plate and suction valve. After compression in the cylinder the same is pumped into the system through valve plate, discharge valve and discharge muffler of the block and discharge pipe connecting the compressor to the system. The pump assembly assembly will be seated seated on the springs in the compressor compressor body and it forms the the frame for all other components. Critical parts of reciprocating compressor . Compressor block : Compressor block castings are made up of grey cast iron by the sand moulding process. The cast iron must be dense enough to prevent seepage. Some Nickel is usually added add ed to give the casting the desired density. Usually the crank case is part of the same casting. This practice cuts down number of joints that might leak. It also permits close alignment between crank shaft and cylinder. Piston : Pistons castings are usually made up of cast iron by the sintering process. Smaller sizes do not have piston rings. The temperature of piston seldom goes higher than 250 degree F. Thus there is not much expansion of either piston or cylinder. Smaller pistons have oil grooves cut in them. Piston pin : Piston pins are made up of Special alloy steel and made through machining process and accurately ground to size. Usually they are hollow to reduce weight. They are usually of full floating type. type. This means the pin is free to turn both connecting rod bushing and piston bushing. Connecting rod : The connecting rod castings are made up of aluminium alloy by pressure die casting process . It holds the piston rigidly by a piston pin and connected to the crank shaft. Crank shaft :
9
Crankshaft is made up of grey cast iron and by sand moulding process. The reciprocating motion is achieved by the crankshaft/ connecting rod / piston assembly. Upper bearing : Upper bearing is usually usually made up of Aluminium alloy and by pressure die die casting process. It is placed in between Crank shaft collar and rotor. It acts as a bearing. Rotor : It is Basically Basically an assembl assembly y of laminatio lamination n stack and aluminum aluminum counter counter weights. weights. Rotor is made made by Die casting casting process by pouring pouring the Aluminium Aluminium in the slots of the laminatio lamination. n. It is the part of the motor which rotates under the action of the magnetic field created by stator. Split pin : Split pins are made up of hardened and tempered steel and made through machining process. This split pins are used to lock the piston pin. Cylinder head : Cylinder head castings for Hermetic compressor are usually made of cast iron/ Aluminium and these casti castings ngs are made made by sand sand mouldi moulding ng proces processs for cast iron iron and by pressu pressure re die casting casting proces processs for Aluminium. The head serves as a pressure pressure plate. It supports and holds valves valves and valve plates in position. It also provides vapour passage into and out of compressor. The pressure of compression may amount as much as 300 psi. These pressure depends on type of refrigerant used. The valve plate must have good support. There must be no leakage at the gaskets on either side of the valve. Cylinder head gasket : Cylinder head gaskets are made up of rubber by rubber moulding process.
Cylinder head fixing screws : Cylinder head fixing screws are made up of tensile strength steel and through machining p rocess. Valve plate : Valve plates are made up of cast iron by sintering process. It supports the suction valve and discharge valve. Discharge valve pins : Discharge valve pins are made up of steel with copper coating and through machining process. Discharge valve : Discharge valves are made up of carbon steel and by blanking and piercing process. Suction valve : 10
Suction valves are made of made up of carbon steel and by blanking and piercing process. Valve reed : Valve reed is made up of carbon steel and by blanking and piercing process. Valve stop : Valve stops are made of cold rolled steel and by of blanking and piercing piercing Process.
Valve guide pin : Valve guide pin is made up of steel and by cold drawing process. Oil pump: Oil pump is made up of steel (C75) and by blanking, piercing and forming process. Rotor : It is Basically an assembly of lamination stack and aluminium counter weights. Rotor is made by Die casting process by pouring the Aluminium Aluminium in the slots of the lamination. lamination. It is the part of the motor which rotates under the action of the magnetic field created by stator. Rotor Lamination : Rotor lamination is is made up of low silicon steel steel semi processed processed through blanking and piercing piercing process. Stator : It is Basically Basically an assembl assembly y of lamination lamination stack stack , copper wire wire wound on the laminati lamination on stack with with the mylor film for insulation. It creates the magnetic field for rotation of the Rotor. Stator lamination : Stator laminations are made made up of low silicon silicon steel, semi processed and by blanking and piercing process . Mylar film : Mylar film is made up plastic material material of polyester film, and by process of plastic extrusion process . Copper wire : Winding wire is made up Copper ,and by drawing process . Stack cleats : Stack cleats are made up of cold rolled steel and by drawing process Heat shrink tube : 11
Heat shrink tube is made up plastic material of polyester film, and by injection moulding process . Connector : Connector is made up plastic plastic material, and by injection moulding process . Stator fixing screws : Stator fixing screw is made up of high tensile strength steel and by machining process. Upper shell : Upper Shell is made up of cold rolled steel EDD quality, and by blanking an d forming process. Crankshaft stop : Crankshaft stop is made up of cold rolled steel EDD quality, and by blanking and forming process. Lower shell : Lower Shell is is made up of cold rolled steel EDD quality, and by blanking and forming process . Machining of compressor components : The following compressor components will undergo the machining on various SPM / GPM / CNC machines to get the accuracy of the parameters /dimensions of the components as per the specifications. specifications. Accuracy of the critical critical parameters parameters / dimensions : Compressor block: Tolerance on cylinder bore • Surface finish of cylinder bore • Flatness of cylinder head face •
-- 10 microns -- 0.33 Ra -- 25 microns
Piston: Tolerance on outer diameter • Surface finish of outer diameter • Tolerance on piston pin hole • Surface finish of piston pin hole •
-- 10 microns -- 0.25 Ra -- 10 microns -- 0.5 Ra
Connecting rod: Tolerance on big end hole diameter • Tolerance on small end hole diameter • Surface finish of big end diameter • Surface finish of small end diameter •
-- 5 microns -- 8 microns -- 0.4 Ra -- 0.4 Ra
Crank shaft: Tolerance on main axis diameter • Tolerance on eccentric axis diameter •
-- 8 microns -- 8 microns 12
• •
Surface finish on main axis Surface finish on eccentric axis
Upper bearing: Tolerance on shaft hole diameter • Surface finish of shaft hole • Flatness of block seating face • Valve plate: Surface finish of both the faces • Flatness of both the faces •
-- 0.2 Ra -- 0.2 Ra
-- 8 microns -- 0.4 Ra -- 10 microns
-- 0.16 Ra -- 10 microns
Gauges: Machined compressor components will undergo in-process/ in-process/ final inspection on various gauges like •
On- line gauges - Marposs / Tespa make
•
Air gauges with dial type display units with 0.5 micron accuracy - Baker / Accurate make
•
Electronic gauges with digital type display units with 0.5 micron a ccuracy - Baker / Accurate make
•
Mechanical gauges : Plug gauges Snap gauges Thread plug gauges Multi gauging fixtures Relational gauges
Cutting Tools: The following type of cutting cutting tools are used in the machining of compressor components to the accuracy of the components as per the specifications. • • • • • • • •
Turning Drilling / CSK Reaming Final boring Milling Honing Grinding (Rough) Grinding (Finish)
- Standard tools / Special brazed tools - Standard / Special - HSS drills - Special - Carbide reamers - Special - Diamond boring tools - Standard / Special cutters - Special honing tools - Special grinding wheel - 38A46 2 L8 V11 - Special grinding wheel - 38A150L8V11 / SA120L6VF8 - Special regulating wheel - A80 RR 51 13
• •
•
•
Lapping (Rough) - Special grinding wheel Lapping (Finish) - Special grinding wheel
- GC 801 TDR 801 - C320 TDR 757
Diamond dressers - Special multi point - 1R6 - J7 - Special Single point - 4 / 1.5 carat Vibro finishing - Ceramic abrasive granules - PI - Elliptical shape 14 x 14 x 5
Oils: The following oils are used in the manufacturing of Hermetic Compressors : •
• • •
• •
Hydraulic oil - Servo 68 Spindle oil Coolant oil - grinding Coolant oil - Lapping - Shell Adrina Washing chemical Compressor oil
- Emkarate RL 68
- non CFC grade
- High spin SW 100 - Servo cut - S - Cimtech - D14 - non CFC grade - non CFC grade - Oakite - 445 NNF - non CFC grade - Emkarate RL 22 H - non CFC grade
Manufacturing process for Compressor Block : The Cast Iron castings of Compressor block will undergo the following Machining and cleaning operations. 1. SPM - I : The following operations are performed on the stator seating side of the compressor block . • • • • • • • • • • •
Rough & Finish milling of stator seating face Rough milling of cylinder head face Core drilling of Cylinder bore Rough boring of cylinder bore Rough facing of upper bearing seating face Rough boring of upper bearing locating hole Drilling of Upper bearing fixing holes Drilling of stator fixing holes Drilling of locating holes Reaming of locating holes. Taping of stator fixing holes
2. SPM - II : The components are turned and positioned to perform the the operations on suspension spring supports side of the compressor block. • •
Rough boring of cylinder bore Rear side chamfering of cylinder bore 14
Trepaning of suspension spring supports Drilling of cylinder head fixing holes • Taping of cylinder head fixing holes • 3. SPM - III : •
The following finishing operations performed on the compressor block. • • • • • • •
Finish milling of cylinder head face Finish facing of upper bearing seating face Finish boring of upper bearing locating hole Finish boring of cylinder bore Counter boring of cylinder bore Milling of half moon Drilling of valve plate locating holes
4. Automa Automati ticc rotary rotary table table Honin Honing g machin machinee : •
The Honing operation for the cylinder bore is performed on the Automatic rotary table honing machine in 10 stations with the Increment of 2 to 3 microns in the ID of the cylinder bore.
5. Autom Automat atic ic brus brushi hing ng machi machine ne : •
The brushing operation for cylinder head face is performed on the Automatic brushing machine.
6. Wa Wash shin ing g mac machi hine ne : •
The machined compressor blocks are sent for the cleaning in The high pressure washing machine with OKAITE - 445, Non - CFC grade chemical.
After cleaning the components will go to the pre assembly. Manufacturing process for Piston Piston : The Sintered Cast Iron piston will undergo the following process before sending into the Pre - assembly. •
Rough grinding of outer diameter on Center less grinder
•
Drilling of retaining pin hole and chamfer cha mfer on SPM
•
Drilling of piston pin hole on Deep hole drilling machine
•
Chamfering of piston pin hole on Drilling machine machine
•
Honing of piston pin hole on Rotary table Honing machine 15
•
Finish grinding of outer diameter on Center less grinding machine
•
Vibro finishing on Thumbler machine
•
Cleaning of the machined pistons in the high pressure washing Machine with OKAITE - 445, non - CFC grade chemical.
After cleaning the components will go to the pre assembly. Manufacturing process for connecting rod : The aluminum castings will under go the following process before Sending into the pre assembly. •
•
•
•
Rough boring of Big end hole and Small end hole on rough Boring machine. Drilling of oil hole on Automatic drilling machine Finish boring of Big end hole and Small end hole on final Boring machine. Cleaning of machined components on screw washing machine.
After washing these components will be going to pre assembly. Manufacturing process p rocess of Crankshaft : The Cast iron castings will undergo the following machining and Cleaning operations before being sent to pre assembly. •
Facing and centering operation on SPM.
•
Turning of Main axis on Auto lathe / CNC lathe
•
Reference face milling on SPM
•
Eccentric axis turning on SPM
•
Oil hole drilling / Helical grooving on SPM
•
Rough grinding of main axis on Centerless grinder
•
Finish grinding of main axis on Centerless grinder
•
Finish grinding of eccentric axis on Cylindrical grinder
•
Vibro finishing of crank shaft on Thumbler 16
•
Cleaning of machined crank shafts in the High pressure washing Machine with OKAITE - 445, non - CFC grade chemical.
After cleaning crank shafts will be sending to Pre - assembly. Manufacturing process of Upper bearing : The Aluminum castings will undergo the following manufacturing process before being sent to pre - assembly. •
Rough boring , rough turning of outer diameter, chamfering , facing of the Upper bearing on Auto lathe.
•
Drilling , Counter sinking , Taping of block fixing holes and Milling of notch on the automatic rotary drilling machine.
•
Finish boring, finish turning of outer diameter on final boring machine.
•
Brushing of block seating face on Brushing machine.
•
Cleaning of machined upper bearings in the High pressure washing machine with OKAITE - 445 grade , non - cfc chemical.
After cleaning these upper bearings will be sending to pre- assembly. Manufacturing process for Valve plates : The Sintered Cast Iron casting valve plate will un dergo the following Process before sending it in to the pre - assembly / assembly. •
Rough grinding of both the faces of valve plates on lapping machine with rough grade grinding wheels.
•
Finish grinding of both the faces of valve plates on lapping machine with finish grade grinding wheels.
•
Cleaning of ground valve plates in the ultrasonic washing Machine with OKAITE - 445 grades chemical.
After cleaning the components will go to the pre - assembly / assembly. Manufacturing process for Upper shell : 1. Shell fabrication : 1 Steel strip coil for the Upper shell will undergo the following Process before sending it to the welding line. De coiling of strip on de coiler co iler • Blanking of sheet from strip on press • Deep drawing of upper shell on press •
17
Trimming of shell on press • Final forming of shell on press •
2. Shell welding : The fabricated shell will undergo the following process before sending it in to the pre - assembly assembly / assembly. assembly. Crank shaft stop is welded on fabricated upper shell on the projection welding machine. Cleaning of the welded shell in the washing machine. • Pre treatment of upper shell • •
After pre treatment these these upper shells will be going to the assembly. assembly. Manufacturing process for Lower shell : 1. Shell fabrication : 2 Steel strip coil for the Upper shell will undergo the following Process before sending it to the welding line. De coiling of strip on decoiler • Blanking of sheet from strip on press • Deep drawing of lower shell on press • Trimming of shell on press • Final forming of shell on press • Piercing of holes on the press •
2. Shell welding : The fabricated shell will undergo the following process before Sending it in to the assembly. • • • • • • • •
Welding of Suspension spring pins on projection projection welding machine Welding of Bracket mounting on projection welding machine Welding of Relay guard on projection welding machine Welding of Relay terminal on projection welding machine Brazing of connector tubes and oil cooler tubes on Brazing Brazing furnace Bending of tubes on Bending fixture Cleaning of the welded shell in the washing machine. Pre treatment treatment of Lower shell
After pre treatment these these Lower shells will be going to the assembly. Manufacturing process for Stamping : Silicon steel sheet is fed into high speed press through a de coiler for auto feed and blanking of the bore , slots for rotor are made . 18
•
Stator slots & stator lamination blanks
•
Stacking of rotor lamination Stator laminations are sent for blueing operation
•
Stamping treatment: •
Loading of stator / rotor packets on pallet/ trolley
•
Removing of lubricants from surface by burn in operation
•
Soaking to extract carbon from the material
•
Cooling down the load to lower temperature
•
Injection of steam at controlled temperature & pressure
•
Holding the material with steam at controlled temperature & pressure to required duration
•
Unloading the material
•
Cooling down to the normal atmosphere temperature
•
Stator/Rotor stampings are ready for next process
Then the stator lamination lamination is sent for stator assembly line and rotor lamination is sent for Rotor line. Manufacturing process for Stator : Lamination will undergo the following process process before sending it to pre assembly. • • •
• • • •
• • • •
• •
•
Stacking , cleating and insulation on stacking machine Run winding of stator on main main winding winding machine. machine. Run winding forming on forming machine. Start winding on Aux. winding machine. Start winding forming on forming machine. Connection of connector on work bench. Welding of connector on connector welding machine. Insertion of connector leads done on the work bench. Pre forming will be on forming m/c. Lacing will be done on lacing m/c. Visual inspection of stator on work bench. Final forming on forming m/c Burnishing of Stator ID on Roller burnishing m/c. After completion of all the operation the stator will go for Final 19
Testing. After completion of the process the component will go to main assembly.
Hermetic system motor : The motor is placed inside housing. The motor must drive the compressor directly. It should have good leak proof electrical connections and must be of an induction type. Motors using rotor windings requiring either brushes or slip rings cannot be used. To calculate the motor speed, the formula is: N = 120 * f / p. Where,
N = RPM f = Frequency p = No. of pole.
Problems associated with Hermetic motors : • • • •
Special cooling provisions must be made. Wiring insulation must be resistant to oil and chemicals in the refrigerant. Manufacturing standards must provide exact alignment of stator, rotor and compressor. Electrical connections through the housing must be electrically perfect and leak proof.
Hermetic motor types : Hermetic motors are generally single single phase induction motors. They are are of four types Split phase Induction motor • Capacitor Start, Induction Run (CSIR ). Capacitor start, Capacitor run (CSCR). Permanent split phase Capacitor ( PSC ). • Resistance start Induction run ( RSIR ). • Resistance start capacitor run (RSCR ). • • •
Hermetic Split Phase Induction Motor : It is the basic type of motor for all Hermetic compressor. The principle of operation is There are two windings – one for starting and one for running. Since starting torque is low such motors must be used on systems with low starting load. This motor is very popular for capillary tube refrigerant refrigerant control. Pressure in this system system balanced in the off cycle. Thus compressor is not required to start under load. Compressors use this type of motor must have some outside starting relay, which might be a Thermal, Current, or Potential relay. Motor Capacitor: 20
Capacitors changes current flow in A.C circuit. It is changed from a single phase to a two phase current flow. Capacitors are used in both starting and running windings. Capacitor start induction run motor ( CSIR ) : It has good starting torque, which is obtained by placing a capacitor in series with the starting winding. It can use current relay, potential relay or thermal relay. Hermetic capacitor start and capacitor run motor ( CSCR ) This generally uses two motors. Both are in the starting winding circuit but only the start capacitor is controlled by the relay switch. When motor is started, the capacitors turn the motor power surges into two phase power and produces a high starting torque. After the motor reaches 60% load or 75% of its rated speed, the relay opens the circuit to the starting capacitor. The running capacitor is left in the circuit. This action produces a two phase motor that is very efficient. The power factor is improved. Large Hermetic units in commercial systems use this type of motor. Permane Perm anent nt split capacitor capac itor motor moto r ( PSC ) : The permanent split phase capacitor is popular for air conditioning systems. It does not use relay. relay. Current Current flows through through both the running winding winding and the starting starting winding winding when power is on . A running capacitor is connected in in series with the starting winding such motors are sensitive to line voltage. A 5% drop in line voltage will cause starting difficulty and over heating. Starting Starting torque torque is low . Thus, if the motor tries tries to start start when the system system is not balanced , the motor will over heat. Resistance start induction run ( RSIR ) : In motors for resistance start, the start winding is made of wire of a smaller dimension than that of the main winding. The result is a large difference in the ohmic resistance, causing the current in the start winding to be less inductive than the current in the main winding, and the required phase displacement is obtained. Resistance start capacitor run ( RSCR ) These type of motor are are having start winding as resistance start, start, and the run winding as capacitor run. run. Hermetic Motor Terminals : The electrical terminals that carry current through the dome must be electrically insulated from the dome or housing. They also must be leak proof. Most motor terminals are fused to glass. The glass, in turn fused to a metal disk . This assembly may be welded to the hermetic dome or housing . The terminal must be leak proof after thousands of heating and cooling and expansion and contraction cycles. Further more, it must have a high insulating value ( 50kv ) Manufacturing Process of Pre - assembly : After machining of each and every component of compressor as per specifications, they are sent for grouping in pre - assembly . This grouping is a selective. 21
Grouping / Selective assembly : Grouping is an important feature of hermetic compressors. • •
The clearance between cylinder bore and piston is 10 microns. The clearance between crank shaft and upper bearing is 18 microns.
Manufacturing the mating parts exactly with the dimensions to get this clearance is not practical in mass production and every machining process requires some tolerance on the sizes of the component. Hence in order to overcome this problem, the components like cylinder block, piston, connecting rod , piston pin , crank shaft, upper bearing are made within a specified range of dimensions. Then these components are classified in different classes like A, B, C etc. based on the size defined for each class. In the selective assembly mating parts of each group are selected such that the difference between OD & ID is as per the specification. In the pre - assembly the grouping is done mainly in three different lines. lines. They are
•
Oil pump -Crank shaft - Upper bearing - Rotor group Cylinder block - Piston Piston - Connecting rod - Piston Piston pin group Valve plate assembly.
•
Manufacturing process of crank shaft - upper bearing - rotor assembly :
• •
The following sequence of operations are performed in the assembly of oil pump , crank shaft, upper bearing and rotor. •
Oil pump is fitted fitted at the small end of the crank shaft shaft .
•
Classification of upper bearing on Air / Electronic gauge
•
Classification of crank shaft on Air / Electronic gauge
•
Selection and coupling of crank shaft and upper bearing such that clearance between both is as per the specification.
•
Placing the thrust washer in the rotor and positioning the rotor in the fixture of the hot fitting machine.
•
Insertion of the crank shaft in the rotor on hot fitting fitting machine.
After the hot fitting the rotor group assembly will be sent to assembly. Manufacturing process of Block- piston - con rod - piston pin assembly: The following sequence of operations are are performed in the assembly of block , piston, connecting rod and piston pin assembly. •
Classification of piston on Air /Electronic gauge 22
•
Classification of connecting rod small end on Air /Electronic gauge
•
Classification of piston pin on Air /Electronic gauge
•
Selection and coupling of Piston and connecting rod
•
Selection and insertion of piston pin in the piston and con rod small end holes
After the insertion of piston pin , this block- piston - con rod group will be sent to assembly. Manufacturing process of Valve plate assembly : The following sequence of operations are are performed in the assembly of valve plate. •
Insertion of discharge valve pins in the valve plate
•
Assembly of discharge valve , valve reed , valve stop
•
Fixing of spring
•
Leak testing of valve plate assembly on leak testing equipment
After the leak testing , the valve plate assembly will be sent to assembly. Manufacturing process of Suction Muffler assembly : The following sequence of operations are are performed in the assembly of Suction muffler. •
Assembly of suction muffler on the cylinder head
•
Fixing of retaining stop
After spring fixing , this suction muffler assembly will be sent to assembly. Manufacturing process of Compressor : •
Various sheet metal parts like Spring pins , Foot brackets , Hermetic terminal , Relay guard will be projection welded on the lower shell on special purpose projection welding machines.
•
Connectors / Tubes of different sizes sizes will be brazed manually to to the welded lower shell.
•
Crank shaft stop will be welded to the upper shell.
•
The upper shell and lower shell shell will be sent for pre-treatm pre-treatment ent in a pre- treatment treatment plant plant and sent to Compressor assembly.
•
Variou Variouss machin machined ed parts parts / select selective ively ly assemb assembled led parts parts will will be assemb assembled led in the lower lower shell shell on a continuous assembly conveyor with pneumatic nut runners. After this assembly it is passed through Dehydration oven for a period of 4 hrs and taken out and Moisture Moisture level is checked ( < 150 mg mg ) 23
•
After placing the upper shell on the lower shell, the compressor is welded on a MIG welding machine and leak tested at 17 kg / sq. cm.
•
After leak testing it is sent on conveyor for painting and baking. The painted compressors will be unloaded and tested for various parameters parameters on final testing machine.
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After testing , the compressors will be sent for packing and then to finished goods stores for despatch.
•
The detailed description of process for Assembly of compressors / sub assemblies / manufacturing of components , that goes into Compressor Co mpressor are as follows. Sequence of operations for the assembly of Compressor : •
On Block - Piston - Con rod assembly, Crank shaft - Upper bearing - Rotor assembly are placed.
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The following components / sub assemblies are placed on the above assembly before the next stage. Stator. Valve plate assembly. Cylinder head & Suction muffler assembly. Discharge muffler cover assembly.
•
The spring bushes and spring fittings are placed on the lower shell.
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The discharge muffler is then brazed to the discharge tube.
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Then it is open tested in a open test test bench and placed in a Dehydration Dehydration oven for dehydration by hot air injection.
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After taking lower shell assembly from dehydration oven the upper shell assembly is kept on the top. Then it is is sent for MIG welding.
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After the welding it is leak tested pneumatically.
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Then it is painted in a paint dipping tank and it is baked.
•
On the final testing the following operations are performed. Vaccumising. Oil charge. Run test. Compression & Absorption test. Noise test. Marking.
• •
High voltage tested and injected with dry air. Packing and OK compressors will be sent to the finished goods stores. INDEX 24
Compressors and Application : • • • • •
What is Compressor Types of Compressors Hermetic Compressor Application of Compressors Function of Compressor in Refrigeration
Refrigeration : • • • • • • • • •
Importance of Refrigeration Global and Indian market - Refrigerator Refrigerator Global and Indian market - Compressor Principle of Refrigeration Types of Refrigeration Vapor compression refrigeration cycle Types of Refrigerants Ozone layer Montreal Protocol
Manufacturing of Compressors :
•
Working principal of Reciprocating Compressor Critical parts of Reciprocating Compressor Machining of compressor components Accuracy of critical parameters / dimensions Gauges Cutting tools Oils
•
Process flow charts / sequence of operations for machining of
• • • • • •
Compressor block Piston Connecting rod Crank shaft Upper bearing Valve plate •
Process flow charts / sequence of operations for press components like Upper shell 25
Lower shell Lamination •
Process flow chart / sequence of operations for assembly Stator
•
Hermetic system motor
•
Hermetic motor types
•
Manufacturing process of pre-assembly Process flow charts / sequence of operations for selective assembly of
•
Block- Piston - Connecting rod - Piston pin group Oil pump -Crank shaft - Upper bearing - Rotor group Valve plate assembly • •
Manufacturing process of Compressor Process flow chart / sequence of operations for Compressor assembly
Gauges : Machined compressor components will undergo in-process/ in-process/ final inspection on various gauges like •
On- line gauges - Marposs / Tespa make
•
Air gauges with dial type display units with 0.5 micron accuracy - Baker / Accurate make
•
Electronic gauges with digital type display units with 0.5 micron a ccuracy - Baker / Accurate make
•
Mechanical gauges : Plug gauges Snap gauges Thread plug gauges Multi gauging fixtures Relational gauges
Cutting Tools : The following type of cutting cutting tools are used in the machining of compressor components to the accuracy of the components as per the specifications. 26
• • • • • • • •
• •
Turning Drilling / CSK Reaming Final boring Milling Honing Grinding (Rough) Grinding (Finish)
- Standard tools / Special brazed tools - Standard / Special - HSS drills - Special - Carbide reamers - Special - Diamond boring tools - Standard / Special cutters - Special honing tools - Special grinding wheel - 38A46 2 L8 V11 - Special grinding wheel - 38A150L8V11 / SA120L6VF8 - Special regulating wheel - A80 RR 51
Lapping (Rough) - Special grinding wheel Lapping (Finish) - Special grinding wheel
- GC 801 TDR 801 - C320 TDR 757
Diamond dressers - Special multi point - 1R6 - J7 - Special Single point - 4 / 1.5 carat Vibro finishing - Ceramic abrasive granules - PI - Elliptical shape • 14 x 14 x 5 Oils : •
The following oils are used in the manufacturing of Hermetic Compressors : •
• • •
• •
Hydraulic oil - Servo 68 Spindle oil Coolant oil - grinding Coolant oil - Lapping - Shell Adrina Washing chemical Compressor oil
- Emkarate RL 68
- non CFC grade
- High spin SW 100 - Servo cut - S - Cimtech - D14 - non CFC grade - non CFC grade - Oakite - 445 NNF - non CFC grade - Emkarate RL 22 H - non CFC grade
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