Coin Sorter For Indian Coins
2004-2005
ACKNOWLEDGEMENT Firstly, I am very grateful to this esteemed institution “Golden for provi providi ding ng Golden Valley Valley Instit Institute ute of Techno Technolog logy y” for me an opportunity to pursue my degree course. I
express
my
sincere
thanks
to
my
Principal
facilities Dr.U.N.Kempaiah for providing me with adequate facilities to undertake this seminar. I would also like to take this opportunity to express my gratitude for the support and guidance extended to me by the
facul ultty
members
of
the
Mech echani anical
Engi nginee neering
Depa Depart rtme ment nt.. I woul would d like like to than thank k H. H.O. O.D D of Mech Mechan anic ical al Enginee Engineering ring
Departm Department ent
Mr. Mr.
D.S D.SRIN RINIVA IVASA
RAO
for
providing me an opportunity and for his invaluable support. My deep and profound gratitude to my internal guide for hi his s keen een in intteres erestt and and bound oundle less ss Dr.U.N.Kempaiah, for encouragement. Finally, I would thank all my friends friends who have helped me directly or indirectly in this seminar.
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CONTENTS CHAPTER
PAGE NO.
1.
INTRODUCTION
1
2.
STUDY OF COIN PARAMETERS
2
3.
POSSIBLE SOLUTIONS
10
4.
COIN FEEDING
13
MECHANISM
15
6.
COIN SORTERS
31
7.
CONCLUSION
33
5.
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CONTENTS CHAPTER
PAGE NO.
1.
INTRODUCTION
1
2.
STUDY OF COIN PARAMETERS
2
3.
POSSIBLE SOLUTIONS
10
4.
COIN FEEDING
13
MECHANISM
15
6.
COIN SORTERS
31
7.
CONCLUSION
33
5.
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INTRODUCTION
Counting of coins is a tedious task when coin collections are large. Say for example, in Banks, Temples, bus depots, shops, etc., they are spending a lot of time and strain for counting their collections. Usually the method they are adopting is first to separate the coins in each denomination and then count the total in each denomination. Finally the totals of each denomination are added to get the grand total. From this we can understand that separating into denominations is a tedious work. So it will be very much helpful to them if a device can be used to separate the coins in denominations. It will be relatively easier to attach provisions for automatic counting once the coins are separated.
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Chapter 2 STATISTICAL STUDY OF COIN PARAMETERS For a systematic approach, the coin parameters which may help to sort out the coins into different denominations are to be identified and their values to be measured.
2.1
COINS AND THEIR PARAMETERS The following four parameters were considered for sorting of the coins:
Diameter/distance Thickness Weight Magnetic property
2.1.1
Diameter/distance
If the shape of the coin is circular then its diameter itself is the parameter. But all the coins are not circular in shape so in case of coins which are not circular in shape, ‘distance’ is considered as the parameter. The term distance refers to either corner to corner distance or flat to flat distance. For example as shown in figure1 for a 5 paise coin which is square in shape, ‘d1’ is the corner to corner to distance while ‘d’ is the flat to flat distance. The distance parameter for 10 paise, 20 paise and 100 paise coins are as shown in the figure 1. The value of diameter/distance of each of the coins is noted in table 1.
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Table 1
The Values of the different parameters of the coins Sl. No . 1
Coin Diameter Denomination and in mm size 05 Paisa 22.20
Distance In mm
Thickness in mm
Weight in gmf
19.00
1.90
1.51
2
10 Paisa [small]
16.00
16.00
1.50
1.96
3
10 Paisa [medium]
23.00
20.14
2.14
1.78
4
10 Paisa [big]
25.80
24.64
1.84
2.27
5
20 Paisa
25.80
24.70
1.84
2.20
6
25 Paisa
19.00
19.00
1.38
2.40
7
50 Paisa [small]
22.20
22.20
1.40
4.00
8
50 Paisa [big]
24.00
24.00
1.54
4.98
9
1 Rs.
[small]
24.90
24.90
1.50
4.86
10
1 Rs.
[medium]
26.00
26.00
1.80
5.94
11
1 Rs.
[big]
28.10
28.18
2.00
7.88
12
2 Rs
[small]
26.20
26.20
1.60
6.14
13
2 Rs
[big]
28.00
28.00
1.80
7.54
14
5 Rs
31.10
31.00
2.20
12.54
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Magnetic/ Nonmagnetic Nonmagnetic Nonmagnetic Nonmagnetic Nonmagnetic Nonmagnetic Lowmagnetic Lowmagnetic Nonmagnetic Nonmagnetic Nonmagnetic Nonmagnetic Nonmagnetic Nonmagnetic Nonmagnetic
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2.1.2 Thickness
For most of the edge has more thickness than the inside surface. The maximum thicknesses of the coins were measured using a vernier caliper with a least count of 0.01 mm and the values noted in table 1.
2.1.3
Weight
Weight of the coin is also an important parameter in sorting out the coins. Hence the weight of each coin has been determined using an electronic weighing machine having readability up to 0.01gmf. The coins were put one by one on the pan and the corresponding weights are obtained on an optical read-out and values noted in table 1.
2.1.4
Magnetic property
If the coins of one denomination are magnetic while the coins of another denomination are non-magnetic, these two denominations can easily be separated by using this parameter.
In each denomination 10 coins were taken at random and on each coin measurement of their magnetic property made at more than one place and it was noted in table 1, whether the coins were magnetic or non-magnetic.
A critical study of the parameters reveals the following information.
a] No single parameter will sort all the coins.
b] The diameter/distance should be used in the first stage of separation for there is a considerable difference in the diameter/distance of each of the coins.
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c] Once the coins are separated using the diameter/distance parameter they can be further separated using the thickness parameter in the second stage and the weight parameter in the third stage.
From the study of magnetic property it is found that some of 25 and 50 paise are magnetic while some other coins of the same denominations were non-magnetic. So it does not seem to be a good parameter for separation.
2.2
Application of coin parameters for separating the coins .
2.2.1
solution using Diameter/Distance
In this method a circular template with a number of holes, in ascending order of diameter in anti-clockwise direction, is held stationary. A thin circular plate which is referred to as rotating arm has holes to accommodate a coin having maximum diameter.
This plate is mounted just above the template as shown in the [figure 2] and driven by a hand wheel.
The rotating arm dimensions should be so designed that only one coin is carried in each of the arm holes. When the coin comes over the corresponding hole it falls through that hole.
It may not be possible to separate all coins using this method alone as diameter/distance of certain coins are very near. While designing the holes on the templates the different orientation of coins have to be taken into consideration. For example 5 paise coin can come either in the corner to corner position or flat to flat position perpendicular to the pitch circles diameter of the holes. If the template hole is
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designed for the flat to flat position of the 5 paise coin then the coin will not fall into the hole if it is coming in the corner to corner position.
This is the main difficulty of this method. All coins except round coins will have more orientations. So some coins will have to be collected together & then separated using other parameter.
2.2.2. Solution using thickness
On a thin plate number of slots of varying width are cut along a line in increasing order [Fig. 4], (each slot has slightly greater width than the min. thickness of the corresponding coin) i.e. this second slot is greater in width than the 1 st slot .This plate is bent into an ‘L’ shape along the line & held inclined at an angle to both vertical & horizontal planes such that when a coin falls on it, it rolls down along the slots. The coin falls down in a slot which is just greater than its thickness. This method alone cannot be used for separating all coins, as many coins have the same thickness. So due to these difficulties, sometimes more than one coin has to be collected in one slot & other parameter should be used for further separation.
2.2.3 Solution using weight of coins
A leaf spring is hinged [Figure 5] at one end and the other end is kept free as a cantilever system. When the coins are allowed to fall on the spring, the free end of the spring deflects, the deflection being proportional to the weight of the coin. A mechanism can be designed to sort out coins using the difference in their deflection.
If the weights of two coins are very near it may be difficult to sense the difference in the deflection so such coins will have to be collected together and further separation should be done using other parameters.
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1.82 30
140
30
26.5 2
FIG.4. SOLUTION USING THICKNESS
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W A
B L X
W A
B Y B
FIG.5. SOLUTION USING WEIGHT IN A LEAF SPRING
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Chapter 3 POSSIBLE SOLUTIONS
From the previous study of each parameter it can be found that it is difficult to separate the coins using only one parameter. Study about magnetic property showed that it cannot be used since the coins are magnetic and non-magnetic in same denomination. So the remaining three parameters i.e. diameter, thickness and weight are to be used for separating the coins. All the different combinations of the above 3 parameters are
3.1 combinations I
(a) Diameter/Distance (First Parameter) (b) Thickness (Second Parameter) (c) Weight (Third Parameter)
By the combination the sorting of the coins is done in the followed way. First the coins will be separated using the parameter diameter/distance. The coins whose diameter/ distance are very close to each other may fall together. Hence those coins which fall together are separated using the thickness parameter in the second stage and further the coins having the same diameter / distance and thickness are separated by using the weight parameter in the third stage.
3.1.1 Diameter/Distance as the First Parameter
From the value in [Table 1] we see that the 50 paisa [small] and the 5 paisa are collected together in the third hole of the template. While 20 paisa and 100 paisa [small and medium] is collected together in the seventh hole of the template.
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It is assumed that the 10 paisa [medium] and 10paise [big] are removed before feeding the coins into the chute. The remaining coins are easily separated in this stage of separation.
3.1.2 Thickness as the second parameter
In third hole and seventh hole two different coins are collected. From [Table 1] it is clear that the 20 paisa and 100 paisa [small and medium] coins collected in the seventh hole can be separated using this parameter. The 5 paisa and 50 paisa [small] can not be separated using this parameter, for the 5 paisa coins does not roll freely over the angle plate.
3.1.3 Weight as the third parameter
The 5 paisa and 50 paisa [small] coins collected together in the third hole of the template can be separated using this parameter. As there is considerable difference in their weight. The coins flow diagram for this combination is shown in fig.6.
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3.2 Combination (II)
(a) Diameter/Distance (b) Weight (c) Thickness
3.3 Combination III
(a) Thickness (b) Diameter/Distance (c) Weight
3.4 Combination IV
(a) Thickness (b) Weight (c) Diameter/Distance
3.5 Combination V
(a) Weight (b) Thickness (c) Diameter/Distance
3.6 Combination VI
(a) Weight (b) Diameter/Distance (c) Thickness 3.7 Selection of one solution
Among the combination (I) to (VI), combination one is selected as trial solution, as the coin sorting takes place more speedily and easily than the other five combinations. The design of a possible prototype is made; to sort coins using the first combination.
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Chapter 4 COINS FEEDING It is mentioned previously in 2.2.1 that the rotating arm of separating mechanism is designed to take only one coin in one hole at a time. To prevent jamming, the coin has to be in horizontal position before it is taken up by the rotating arm. That is, coins have to be stacked one above the other. This cannot be achieved by merely pouring the coins into the feeding funnel which has direct contact to the rotating arm. Hence, a mechanism was thought for feeding the coin one by one stacking the coin one above the other.
4.1 Rotating Plate with Gravity Feeding
A plate with a number of holes, each capable of seating only one coin at a time is rotated over a stationary plate, he coin falls down due to gravity when they come above the hole of the stationary plate [fig 7].A guiding funnel below this hole loads the coin to the rotating arm of the separating mechanism.
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Chapter 5 MECHANISM
The main parts of the coin sorter are 5.1 SEPARATING MECHANISM
(a) Template (b) Rotating arm (c) Angle plate (d) Leaf spring and spring housing (e) Connecting [vertical] shaft (f) Coin guide (g) Coin collectors
5.1.1 Template
Template is one of the most critical part of the setup. It is a circular alluminium plate, having eight holes in ascending order of the diameter. The template is shown in fig 8. The first hole in the template catches the coin having the least diameter/distance(10 paise[small]).The last hole catches the coin having the largest diameter/distance (200 paise[small]).The diameter/distance of each coin and diameter of their corresponding holes is shown in table 2.
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The Diameter of the coins and the diameter of their respective holes on the template
Table 2
Sl.
Coin No.
Diameter/Distance Denomination
hole size
in mm
in mm
1.
10 paise [small]
16.00
17.00
2.
25 paise
19.00
20.00
3.
50 paise[small]
22.20
22.60
4.
10 paise[medium]
23.00
23.50
5.
50 paise [big]
24.00
24.50
6.
100 paise [small]
24.90
25.50
100 paise [medium]
25.80
26.20
200 paise [small]
26.20
26.70
7.
8.
20 paise and
5.1.2 Rotating Arm
It is circular plate of alluminium alloy, having 11 equispaced holes of 28.5mm diameter on a 189mm P.C.D.[fig 9].Only one coin can be seated at a time inside a hole[for the thickness of the plate is 1.5mm].The coins dropping into the guiding funnel are continuously picked up by the holes on the rotating arm and carried over the holes of the template, in an anti-clockwise direction.
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5.1.3 Angle Plate
The principle of separating coins using thickness as a parameter as been discussed in section 2.2.2 .the seventh hole of the template collects 20 paisa and the 100 paisa coins which are guided over the angle plate , inclined at 30 degree to the horizontal, so that the coins troll freely over it. The 100 Paisa coins fall into the slot on angle plate while the 20 Paisa coins cross the slot and are collected at the end of angle plate. The details of the angle plate are shown in the fig.10.
5.1.4 Leaf Spring and Spring Housing
As discussed in section 2.2.3 a leaf spring is designed for the separation of coins having different weights. The 5 paisa and the 50 paisa [small] coins collected together in the third hole are separated using this method. Five paisa coin has a weight of 1.5 gmf while 50 paisa [small] coin has a weight 4.0 gmf. So they have a considerable difference in weight and hence, they can be separated using weight as a parameter.
The spring is considered to be a cantilever with load at free end. A phosphor bronze sheet of 0.2 mm thick and 20 mm wide is selected for making the spring. The deflection of free end of the spring is obtained as follows, with the help of figure shown on the page no 24.
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1.82 30 30
140
26.5 2
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W A
B L X
W A
B Y B
Mx
= - W (1 –x)
EI d²y/ dx² = - [- W (1- x)] = Wl - Wx EI dy/dx
= Wlx – Wx² / 2 + C1
---------------------------- (a)
EIy
= Wlx² - Wx²/ 6x + C1x + C2
---------------------------- (b)
At x=0, dy/dx = 0 and y=0 Substituting in (a), C1 = 0 Substituting in (a), C2 = 0 EI dy/dx = Wlx – Wx² / 2 and EIy = Wx² /2- Wx²/ 2 At x=1 Slope θB = 1/EI (Wl² - Wl²/2) = Wl²/EI Deflection YB =1/EI (Wl³ /2 - Wl³ /6) = Wl³ /3EI For a section of 20 mm width And 0.2 mm thickness, I= bd³ / 12 = 2* 0.02³ / 12 = 16 * 10-6 / 12 = 4/3 * 10-6 cm4 W= 1.5 * 10-3 kg for 5 paisa. For YB = 2 cms l3 = 2 * 3EI/W = 2*3*1.132.106*4*10-6 /1.5*10-3*3 l3=3018.67 cm3 l=14.45 cms say length of spring is 15 cms Department Of Mechanical Engg. , G.V.I.T.
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Deflection for 50 paisa [small] coin
Weight of 50 Paisa [small] coin = 4.0 /10³ kgs Yв = (4 * 10³ *15³ * 3) / 3 * 1.132 * 106 * 4 * 10-6) Yв =2098 cms
Hence, the deflection of the spring for the 50 paisa [small] coin is 2.98 cms.
The spring housing is so designed such that the 5 paise coin falls out through the hole provided in to housing, while 50 Paisa coin falls in side the housing.
The spring is fixed to the housing with the help of two rivets; the housing is fixed to the coin guide with the help of a clamp. The details of the spring and housing are shown in the fig 11.
5.1.5
Connecting [Vertical] shaft
The shaft made of mild steel. The details of the shaft shown in the fig. 12.
5.1.6
Coin Guide
The coin guides are made of sheet-metal they are hollow cylindrical pipes. Flattened at the ends, and stuck to the template holes at the bottom using araldite. PVC tubes are inserted into the guides to lead the coins in to their respective collectors.
5.1.7
Coin collector
These are square boxes of mild steel, inserted into their holders which are welded to the horizontal plate fixed to the frame.
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5.2 FEEDING MECHANISM
(a) Rotating feed plate (b) Fixed feed plate (c) Feed driving shaft (d) Feeding Chute (e) Guiding Funnel
5.2.1 Rotating feed plate
It is a 1.5mm thick round plate made out of aluminum alloy, and as 10 equispaced holes on a 180 mm P.C.D. The holes have diameter of 32mm in order to provide space for the maximum coin size. A hole can contain one coin at a time. The holes carry the coin to the top where it falls down into the guiding funnel or into the 200 paise, 500 paisa slots depending on their diameter. At the center of the rotating feed plate, there is a small hole of 11.2mm diameter through which the threaded end of the feed driving shaft inserted and fixed by means of a nut. It also contains four holes of 5mm diameter on 30.5mm P.C.D., to fix the boss on to it.
5.2.2 Fixed Feed Plate
It is a 4mm thick aluminum plate fixed to the frame which is supported on stand. It has three holes 26.3mm, 28mm and 32mm on a 180mm P.C.D. as shown in the fig 14. The center of the plate has a hole through which the feed driving shaft rotates. There are four counter sunk holes on a 55.5mm p.c.d to fixed the boss on to it.
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5.2.3 Feed Driving Shaft
The Feed driving shaft is made of mild steel the details of which are shown in fig 12.
5.2.4 Feeding Chute
It is one of the important parts of the coin sorter. A pipe of 35mm diameter is cut at 30 degree to the vertical and joined to from an elbow pipes. One end of the elbow pipe is flattened and the rectangular hopper is inserted into it, and welded. The circular end of elbow rests just above the rotating feed plate. The coins fed into the funnel get stacked one above in the elbow, and are continuously picked-up by the rotating plate. The funnel is fixed to the inclined frame with the help of L shaped, strip welded to it, and an adjustable mechanism, to alter the clearance between the rotating feed plate and the funnel to the desired level [fig 16]
5.2.5 Guiding Funnel
The coins falling one by one from the feeding system have to be taken to the hole of the rotating arm of the separating system. This is the function of the guiding funnel. Coins fall in to the guiding funnel due to gravity from the hole of fixed plate. The coins slide down the guide guiding funnel and reach the rotating arm. When a hole of the rotating arm comes below the coin it picks up the coin and carries it over the template for sensing the coin denomination.
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DESCRIPTION OF THE PARTS IN THE GROUP ASSEMBLY DRAWING
NO. ON DRAWING 1
QUANTITY 1
Funnel
2
4
Screw “MS”
3
1
Boss [Rotating Feed Plate]
4
1
Rotating Feed Plate
5
1
Stationary Feed Plate
6
1
Boss [Fixed Feed Plate]
7
4
Screw “MS”
8
1
Feed driving Shaft
9
4
Bevel Gears
10
1
Guiding Funnel
11
1
Boss [Rotating Arm]
12
1
Rotating Arm
13
1
Template
14
1
Boss [Template]
15
1
Angle Plate
16
1
Connecting [Vertical] Shaft
17
1
Leaf Spring and Housing
18
1
Driving Shaft
19
1
Driving Shaft Housing
20
1
Connecting [Vertical] Shaft House
21
1
Hand Wheel
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DESCRIPTION
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1)
•
•
•
•
•
•
•
Speed: 2000 coins per minute Coin off-sort bagging attachment Easy to read LED display User friendly controls Hopper capacity: 4,000 coins Weight: 28 lbs. Power: AC 100/120w
2)
• Speed: 3500 coins per minute • Hopper capacity: 10,000 coins • Weight: 36 lbs. • Power: AC 100/120w
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3)
• Speed: 1800 coins per minute • Hopper capacity: 2,000 coins • Weight: 19 lbs. • Power: AC 100/120w
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