Inventive creation of arduino programmed gear cutting in ... · Gear cutting machines are used to make chain gears, gears with straight and slanted teeth through processes such as
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IJRTI1703007 International Journal for Research Trends and Innovation (www.ijrti.org) 31
III. DEMERITS OF EXISTING MACHINES
The above mentioned CNC machine is of high cost and the purpose of implementing this machine is only to cut gears then it might be of unwanted investment of money. However it is difficult for small scale industries to afford a huge sum of money on this
type of single machines which able to do only single operation, even though the process is completely automated.
Another major drawback in the existing system is that if to go for individual machines for individual operations the space occupied by the individual machines is comparatively high and alternatively the maintenance cost increases a lot, which cannot be
afforded by small scale industries.
IV. COMPONENTS USED AND ITS WORKING
ELECTRIC MOTOR
There are two electric motors in this proposed model, a DC motor for driving the cross slide through a belt drive and a DC
stepper motor for rotating the work piece to the preferred step angle for required number of teeth.
IV.1 DC MOTOR
The DC motor shown in the fig 2.1 is used to drive the cross slide to provide linear movement. This motor can deliver high
output torque as it consists of worm & worm wheel arrangement fitted into its shaft and is housed perfectly. Rotation is possible in
both clockwise and also in counterclockwise directions.
Specifications
The electric power supply necessary to run the DC motor is obtained from a step-down transformer and a bridge rectifier.
Voltage and Power 12 V DC, 50 Watts
Load Current 10 A
No Load Current 2 / 2.5 A
Speed 60 RPM
Torque 5 N-m
Table 2.1 Technical specifications of DC Motor
Calculations
The speed of the DC motor is reduced for slow movement of the cross slide. This is achieved by coupling the rotor of the
DC motor to a pulley by a belt drive. So, this will reduce the rotating speed while increasing the torque.
Motor pulley diameter = 0.04 m
Driven pulley diameter = 0.12 m
Therefore, Reduction Ratio = 3 : 1
Speed of the motor (Driving) = 60 RPM
Driven speed (Driven) = 20 RPM
Driving Torque = 5 N-m
Driven Torque = 15 N-m
IV.2 NEMA 34 DC STEPPER MOTOR
The circular indexing of the work piece is made through DC stepper motor shown in the fig 2.2. The stepper motor is
used to rotate the work piece to the required step angle and hold at the step angle thus providing lock mechanism for the work piece
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Specifications
The electric power supply necessary to run the DC stepper motor is obtained from a step-down transformer and a bridge rectifier.
Rated Voltage 2.8 V
Rated Current 1.68 A
Phase Current 4.2 A
Number of Phase 2
Step angle 1.8 degree
Holding Torque 45 Kg-cm / 4.41 N-m
Resistance per phase 0.87 ohm
Inductance per phase 7.3 mH
Rotor Inertia 1400 g-cm2
Configuration 4 wire bipolar motor
Table 2.2 Technical specifications of NEMA 34 DC Stepper Motor
Calculations
The torque of the DC stepper motor is increased to withstand the cutting force generated during the cutting operation. This is
achieved by coupling the rotor of the DC stepper motor to a pulley by a belt drive. So, this will increase the torque.
Motor pulley diameter = 0.04 m
Driven pulley diameter = 0.12 m
Therefore, Reduction Ratio = 3 : 1
Driving Torque = 4.41 N-m
Driven Torque = 13.24 N-m
IV.3 MICRO-STEPPING MOTOR DRIVER (RMCS-1101) The motor drivers are used for quiet and smooth operation of the motor. The RMCS-1101 motor driver shown in fig 2.3
achieves micro-stepping using a synchronous PWM output drive and high precision current feedback and this is absolutely silent
when the motor is stopped or turning slowly. It virtually eliminates stopped-motor heating regardless of power supply voltage.
The RMCS-1101’s closed-loop control gains are calibrated on start-up based on motor characteristics and also adjusted
dynamically while the motor is in motion. This control algorithm makes it capable of achieving better torque at higher speeds in
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Peak
Current
SW 6 SW 7 SW 8
1.00A OFF OFF OFF
2.00A OFF OFF ON
2.80A OFF ON OFF
3.30A OFF ON ON
4.20A ON OFF OFF
5.00A ON OFF ON
6.00A ON ON OFF
7.00A ON ON ON
Table 2.6 Switch Selection for Motor Coil Current Setting
Switch Selection for Step Resolution Setting
Steps/Re
v SW 1 SW 2 SW 3 SW 4
200 ON ON ON ON
400 OFF ON ON ON
800 ON OFF ON ON
1000 OFF OFF ON ON
2000 ON ON OFF ON
3200 OFF ON OFF ON
4000 ON OFF OFF ON
8000 OFF OFF OFF ON
1600 ON ON ON OFF
6400 OFF ON ON OFF
10000 ON OFF ON OFF
12000 OFF OFF ON OFF
12500 ON ON OFF OFF
12800 OFF ON OFF OFF
16000 ON OFF OFF OFF
20000 OFF OFF OFF OFF
Table 2.7 Switch Selection for Step Resolution Setting The table 2.7 shows the various switch selection for the step resolution setting for the stepper motor to drive according to the
required step angle. For various steps per revolution the switches of the motor driver is to be kept ON/OFF.
Calculations The number of pulse to the stepper motor is decided on the number of teeth to be cut and the pulley ratio. By calculating the
resolution we can find the required pulse for the operation.
Assuming the number of teeth to cut is 25. Based on this the resolution and pulse are calculated.
Angle to be tilted for each tooth = 3600 / 24 = 150
Number of Operating Pulses = Angle to be tilted / Required Resolution = 150 / 0.030 = 500 Pulses
Motor pulley diameter = 0.04 m
Driven pulley diameter = 0.12 m
Therefore, Reduction Ratio = 3 : 1
Therefore, the actual number of operating pulses to be loaded by considering the pulley ratio is,
Number of Operating Pulses = 3 x 500 = 1500 Pulses
IV.4 INDUCTION MOTOR
An induction or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque
is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor therefore does not require mechanical commutation, separate-excitation or self-excitation for all or part of the energy transferred from stator to rotor,
as in universal, DC and large synchronous motors. An induction motor's rotor can be either wound type or squirrelcage type.
Three-phase squirrel-cage induction motors are widely used in industrial drives because they are rugged, reliable and economical. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans.
Although traditionally used in fixed-speed service, induction motors are increasingly being used with variable-frequency drives
(VFDs) in variable-speed service. VFDs offer especially important energy savings opportunities for existing and prospective
induction motors in variable-torque centrifugal fan, pump and compressor load applications. Squirrel cage induction motors are
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very widely used in both fixed-speed and variable-frequency drive (VFD) applications. Variable voltage and variable frequency
drives are also used in variable-speed service. A three phase induction motor is shown in fig 2.4.
Specifications
The table 2.8 shows the technical specifications of the three phase induction motor.
Voltage 440 V
Current 3 A
Speed 2800 RPM
Connection Delta
Horse Power 1 HP
Table 2.8 Technical specifications of 3 phase Induction Motor
IV.5 ARDUINO UNO
Arduino is an open-source platform used for building electronics projects. Arduino consists of both a physical programmable
circuit board (often referred to as a microcontroller) and a piece of software, or IDE (Integrated Development Environment) that
runs on your computer, used to write and upload computer code to the physical board. Arduino UNO is a microcontroller board
based on the ATmega328P which is shown in fig 2.5.
An Arduino board consists of an Atmel 8-, 16- or 32-bit AVR microcontroller with complementary components that facilitate
programming and incorporation into other circuits. An important aspect of the Arduino is its standard connectors, which lets users
connect the CPU board to a variety of interchangeable add-on modules known as shields. Some shields communicate with the
Arduino board directly overvarious pins, but many shields are individually addressable via an I²C serial bus—so many shields can
be stacked and used in parallel. Official Arduinos have used the megaAVR series of chips, specifically the ATmega8, ATmega168,
ATmega328, ATmega1280, and ATmega2560. A handful of other processors have been used by Arduino compatibles. Most
boards include a 5 volt linear regulator and a 16 MHz crystal oscillator (or ceramic resonator in some variants), although some designs such as the LilyPad run at 8 MHz and dispense with the onboard voltage regulator due to specific form-factor restrictions.
This makes using an Arduino more straightforward by allowing the use of an ordinary computer as the programmer. Currently,
optiboot boot loader is the default boot loader installed on Arduino UNO.
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Specifications
The technical specifications of the Arduino UNO and other related specifications are described on the table 2.9.
Microcontroller ATmega328
Operating Voltage 5 V
Input Voltage
(recommended)
7 – 12 V
Input Voltage (limits) 6 – 20 V
Digital I/O Pins 14 (of which 6
provide PWM output)
Analog Input Pins 6
DC Current per I/O
Pin
40 mA
DC Current for 3.3 V
Pin
50mA
DC Current for 3.3 V
Pin
X 32 KB
(ATmega328) of which
0.5 KB used by boot
loader
SRAM 2 KB (ATmega328)
EEPROM 1 KB (ATmega328)
Clock Speed 16 MHz
Length 68.6 mm
Width 53.4 mm
Weight 25
Table 2.9 Technical specifications of Arduino UNO
IV.6 RELAY
A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other
operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a low-
power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be
controlled by one signal. The first relays were used in long distance telegraph circuits as amplifiers: they repeated the signal coming
in from one circuit and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges and early
computers to perform logical operations.
A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor.
Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. Relays
with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload
or faults; in modern electric power systems these functions are performed by digital instruments still called "protective relays".
When an electric current is passed through the coil it generates a magnetic field that activates the armature and the consequent movement of the movable contact either makes or breaks (depending upon construction) a connection with a fixed contact. If the
set of contacts was closed when the relay was de-energized, then the movement opens the contacts and breaks the connection, and
vice versa if the contacts were open. When the current to the coil is switched off, the armature is returned by a force, approximately
half as strong as the magnetic force, to its relaxed position. Usually this force is provided by a spring, but gravity is also used
commonly in industrial motor starters. Most relays are manufactured to operate quickly. In a low-voltage application this reduces
noise; in a high voltage or current application it reduces arcing.
IV.7 TRANSFORMER
The transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. A varying
current in the primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic flux through
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the secondary winding. This varying magnetic flux induces a varying electromotive force (E.M.F) or voltage in the secondary
winding. The transformer has cores made of high permeability silicon steel. The steel has a permeability many times that of free
space and the core thus serves to greatly reduce the magnetizing current and confine the flux to a path which closely couples the
windings. A 12-0-12 step down transformer is shown in fig 2.7.
A varying current in the transformer's primary winding creates a varying magnetic flux in the core and a varying magnetic field
impinging on the secondary winding. This varying magnetic field at the secondary induces a varying electromotive force (EMF) or
voltage in the secondary winding. The primary and secondary windings are wrapped around a core of infinitely high magnetic
permeability so that all of the magnetic flux passes through both the primary and secondary windings. With a voltage source
connected to the primary winding and load impedance connected to the secondary winding, the transformer currents flow in the
indicated directions. According to Faraday's law of induction, since the same magnetic flux passes through both the primary and
secondary windings in an ideal transformer, a voltage is induced in each winding in the secondary winding case, according to the primary winding case. The primary EMF is sometimes termed counter EMF. This is in accordance with Lenz's law, which states
that induction of EMF always opposes development of any such change in magnetic field. The transformer winding voltage ratio is
thus shown to be directly proportional to the winding turns ratio. According to the law of Conservation of Energy, any load
impedance connected to the ideal transformer's secondary winding results in conservation of apparent, real and reactive power.
Instrument transformer, with polarity dot and X1 marking on LV side terminal. The ideal transformer is a reasonable approximation
for the typical commercial transformer, with voltage ratio and winding turns ratio both being inversely proportional to the
corresponding current ratio.
IV.8 MILLING GEAR CUTTER
The milling gear cutter is a cutting tool used to cut the teeth into the work piece. Based on the module various types of gear tooth
profile can be made. A milling gear cutter is shown in fig 2.8. The cutter is generally made of high speed steel (HSS), carbide,
cobalt, etc.
Specification
The technical specifications of the milling gear cutter are shown in the table 2.10.
Material High Speed Steel
Module 2.25 mm
Pitch Circle Diameter 55 mm
Addendum Circle
Diameter
63 mm
Bore Diameter 30 mm
Table 2.10 Technical Specifications of Milling Gear Cutter
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rotates in counter clockwise direction bringing the cross slide back till it touches the limit switch LS2. During this backward
movement of the cross slide, no cutting operation is performed. Now a pulse and direction signal from the Arduino UNO is given to
the RMCS- 1101 microstepping motor driver. Depending upon the required step resolution and peak current the switches in the
driver must be kept ON/OFF. For 200 steps per revolution and 2.80A peak current, the switches SW1-SW4, SW7 is kept ON and
the remaining switches are kept OFF. This driver converts the pulse signal from the Arduino into voltage signal through NPN
transistors. By this voltage the stepper motor rotates the work piece to the next tooth. Then the wiper motor starts rotating clockwise thereby continuing the cycle till all teeth are cut. After the completion of the cycle, the controller will turn off the system
automatically.
The fabricated setup has been successful implemented in the drilling machine as shown in the fig 4.1 & 4.2.
VI.3 COST OF FABRICATION
The total cost accounting both to mechanical setup and electronics is shown in the table 4.1.