Deepak Mahajan

7/30/2019 Deepak Mahajan

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INDUSTRIAL AUTOMATION

TRANSFER DEVICES AND FEEDERSASSIGNMENT-2

NAME: - DEEPAK MAHAJAN

ENTRY NO.: - 2009EME60

BRANCH: - MECHANICAL ENGINEERING

SEMMESTER: - 7TH

SEM


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TRANSFER DEVICES:-

Transfer devices are special purpose systems where the components are

automatically transferred from one machining head to another. Operations are

performed sequentially. Each machining head carries out one operation until, when

the component reaches the end of the line; all the necessary operations have been

performed.

Types of Transfer Devices: There are two types of transfer devices:

(a) In line transfer machines

The in-line assembly machine consists of series of automatic workstations locatedalong an in-line transfer system. The components are transferred automatically from

one machining station to another either by pulling supporting rails by means of an

endless chain conveyor or by pushing along the continuous rails by air or hydraulic

pressure. The components are loaded manually or automatically onto the central

bed.

In comparison with rotary transfer systems the manufacturing costs of linear

transfer systems are generally 10 to 20% higher according to type. Space

requirements are greater as compared to rotary transfer system


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(b) Rotary indexing table transfer machines.

These machines are used when few machining stations need to be employed. The

machining heads are arranged radially along the periphery of rotary indexing table.

The table rotates about a vertical axis and its movement could be continuous or

intermittent.

Rotary Transfer Machines automatically feed multiple workstations from a

rotating turret. This combines automated part feed with multiple simultaneous

operations, streamlining the machining process significantly. The rotary transfer

technology indexes a work piece from station to station via a rotary table, with

operations performed at each station. The number of stations allow for easier

balance between long and short operation cycles. Because the tools rather than

work piece are rotating, it is possible to insert and machine non-round stock of

virtually any shape.

Machining operations are typically hole-making operations (drilling, cross

drilling, tapping, boring, counter boring etc.) but can also include milling, turning, cut-

off, broaching etc.

Rotary arrangement saves floor space and presents a more compact

arrangement. This type of arrangement is best suited for automated assembly of

product.


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(c) Rotary Index Table :-

Rotary index tables are used to index / transfer parts and

components in defined, angular increments so that they can be machined, worked,

or assembly in multiple operation. Tables consist of a circular steel plate, one or

more spindles, a drive system, and pins that holds parts and components in place.

Rotary index table have either fixed or adjusting index angles. During each

revolution, the table stops a specified period of time so that operation can be

performed at each station. Rotary index table are powered by pneumatic and electric

motors, hydraulic drives, and manual actuation. Drive mechanism can be located

above, below, behind, or the side of table surface. Pneumatic rotary indexing are

suitable are small and medium loads. Electrically powered table are generally faster

than pneumatic device and can handle heavier loads. Tables that are powered by

hydraulic drives use pressurized fluid that transfer rotational kinetic energy. Manually

actuated rotary indexing table often include a hand crank or are loosened, turned

and adjusted by hand.

Fig. Rotary index table


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Transfer mechanisms

(a)Linear Transfer Mechanism:

Walking beam system:In this type of linear transfer mechanism, the work parts are lifted up from their

workstation locations by a transfer bar and moved one position ahead, to the next station. The

transfer bar then lowers the parts into nests, which position them more accurately for

processing.

The advantages of walking beam machines include lower machine cha sis cost and significant

reductions in fixturing costs. This system lends itself well to very high speed machines.

Fig. walking beam system


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Powered roller conveyor system: This type of system is used inautomated flow lines. The conveyor can be used to move parts or pallets. Roller

conveyors are flexible, robust and highly efficient.


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Chain drive conveyor system:

A chain or steel belt is used to transport the work carriers. Chain drive conveyor system as

shown in the diagram can be used for continuous, intermittent or non-synchronous movement

of work parts.


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(b) Rotary transfer mechanism:There are various methods used to index a circular table or

dial at various equal angular positions corresponding to workstation locations. Some of the

methods are described below:

1. Rack and Pinion:The Rack and pinion mechanism is not suited for high speed

operation often associated with indexing machines. The device uses piston to drive

the rack, which causes the pinion gear and attached indexing table to rotate.

2. Ratchet and pawl:This mechanism is based on a wheel that has teeth cut out of it

and a pawl that follows as the wheel turns. As the ratchet wheel turns, the pawl fallsinto the dip between the teeth. The ratchet wheel can only turn in one direction -in

this case anticlockwise. Its operation is simple, but somewhat reliable owing to wear

and sticking of several of the components.

Fig. Ratchet and pawl mechanism

3.Ganeva mechanism:The Ganeva type mechanism has more general

applications in assembly machine but its cost is higher than the mechanism described

earlier. A Ganeva mechanism shown in diagram is used to provide an intermittent

rotational motion of the driven part while the driver wheel rotates continuously. If the

driven member has eight slots for eight-station indexing machines, each turn of driver

will cause the table to advance one-eight of a turn. The driver only causes movement

of the table through a proportion of its rotation.

Fig. Ganeva Mechanism


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Advantage and disadvantages of transfer machines :-

Advantages:

(a) Greater accuracy is achieved.

(b) Production time is reduced.

(c) Reduced cost of component.

(d) Greater output.

(e) Better use of floor space.

(f) Heavy and irregular parts can be machined

(g) Fewer operators are required.

Disadvantages:

(a) Initial cost is high.

(b) Breakdown of one machine leads to stoppage of all machines.

(c) Complex control system.

(d) Limited to high production industries.

.


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FEEDERS:-

A feeder is an extremely important element in a bulk material handling system, since

it is the means by which the rate of solids flow from a hopper or bin is controlled

when a feeder stops, solids flow should cease. When a feeder is turned on, there

should be a close correlation between its speed of operation and the rate of

discharge of the bulk solid.

Classification of feeders: There are two basic types of feeders used in industrial

plants:

(a)Volumetric feeder

It modulates and controls the volumetric rate of discharge from bin. Most common

types of such feeders are screw, belt, rotary valve, and vibrating pan.

Fig. Volumetric feeder.


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(b)Gravimetric feeder.

It modulates the mass flow rate. This can be done either on

continuous basis (the feeder modulates the mass per unit time of material discharge)

or on batch basis (a certain mass of material is discharged and then the feeder shuts

off) Common types of gravimetric feeders are loss-in weight and weight belt.

Fig. Gravimetric feeder.

PARTS OF FEEDING DEVICES :-

(a) Hopper: Hoppers are receptacles for the temporary storage of material. They are

designed so that stored material can be dumped easily. Hoppers can be made out of

aluminium or steel for heavy-duty use, and plastic for light duty applications.

(b) Chute: Chutes are loading devices in which work pieces arranged in a single row

are restored manually to ensure their going into the machine in correct position. The

work pieces are picked signally at the other end by the feed track and fed into

machine work area Chutes may be straight or spiral

(c) Magazines: Magazines are loading devices adopted to hold a pile of work of

various shapes and sizes, for further loading into machine Magazines can be sub-

divided into flat and chute magazines.


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(d) Separator: Many times work pieces are to be fed into machine at set intervals of

time so, work pieces are separated by interrupting the flow of parts to the feeder and

move it slightly into machine fixture. This can be done with the help of separators.

(e) Parts feeder: It is often extremely costly to maintain part order throughout the

manufacture cycle. A part feeder is a machine that orients such parts before they are

fed to an assembly station.

(f) Feed track: A feeder track is used to transfer the components from hopper and

part feeder to the exact location of the assembly work head, maintaining proper

orientation of the parts during the transfer.

(g) Escapement and Placement Device: The purpose of escapement device is toremove components from the feed track at time intervals that are consistent with

cycle time of the assembly product.

(h) Selector and Orientor: The purpose of selector and orientor is to establish the

proper orientation of the components for the assembly work head. An orientor is a

device that allows properly oriented parts to pass through but provides a

reorientation of components that are not properly oriented initially.


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vibratory Bowl feeder :-

Vibratory parts feeding is a technology used to orient

(proper position), singulate (proper quantity) and differentiate (separate/sort) and

move parts to a desired location. Vibratory Bowl feeders are used for feeding in

oriented form a wide range of components such as steel balls, nuts, belts, washers,

rivets, etc. The vibrating bowl feeder is the oldest and still most common approach

to the automated feeding of such components. There is no moving parts in the

equipment and thus no wear and tear and no need of maintenance.

Fig. vibratory bowl feeder.


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Vibratory feeder terminology:

Hopper:The storage hopper is the storage area provided to backlog bulk parts prior to

entering the feeder bowl. This hopper eliminates overloading or insufficient loads of parts,

causing the bowl not to function as required.

Basic bowl:The band, bottom and track assembly prior to any tooling for a specific

part. Basic bowls are not off-the-shelf standard items. They are individually designed and

can be supplied for any profile of part up to approximately 5 long.

Feeder bowl:

The feeder bowl is the actual orientating and feeding device thatorients the part to your machine requirements and the heart of the system.

Rate (or Feed rate):The number of parts per minute, per hour, which you require

to meet your production requirements.

Orientation:Positioning of part in the attitude you desire for your operation.

Selector:An area of the system designed and custom fit to profile only the

properly positioned parts. Parts entering a selector, which are not in proper position, are

diverted out of the feed line.

Confinement:The fabrication installed to assure 100% control of the part after a

selector ejects improperly positioned parts.

Return Pan: An extra pan like area welded to the outside of the bowl, whichcatches excess and rejected parts falling from the tack. The pan guides these parts back into

interior of the bowl for recirculation.

Discharge of the feeder bowl:This is the last section of the bowl. In most

cases, it is a straight exit that confines the parts the parts after they are oriented.


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Tack switch:A switch of any type, which turns the feeder off whenever, the

tracking to the machine becomes full. The tack switch also helps to eliminate wear, noise and

jams within the feeder. Air, photoelectric, proximity and electro-mechanical track switches

can be used.

Classification of Vibratory Feeders:

(a) Adjustable rate vibratory feeders

(b) Bowl feeders

(c) Centrifugal feeders

(d) Electromagnetic vibrating systems

(e) Electromagnetically vibrating equipment(f) Fixed rate vibratory feeders.

(g) Flexible feeders

(h) Natural frequency conveyors or feeders

(i) Pneumatic feeders

(j) Straight line feeders.

Construction and working of vibratory bowl feeders Vibrating bowl feeders are commonly

used for aligning and feeding small parts. A typical vibrating bowl feeders consist of a bowl

mounted on a base by three or four inclined leaf springs. As parts move up an inclined track

along the edge of the bowl, tooling in the bowl orients parts into the proper orientation or

rejects misaligned parts into the center of the bowl where they begin their travel up the track

again.

A part feeder takes in a stream of identical parts in arbitrary orientations and

outputs them in a uniform orientation. It consists of a bowl filled with parts surrounded by a

helical metal track.

A picture of section of feeder track is given in diagram. The parts move

from the right to the left on the feeder track. Parts in undesired orientations fall back into thebowl, other orientations remain supported.


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Fig. Vibratory bowl feeder.

There are varieties of controls available for the different types of vibratory feeders.

Parts feeder provide a cost effective alternative tinanua1 labor, saving manufacturers

valuable time and labor costs. One operator can oversee a number of automated

machines, as opposed to one worker hand loading one machine. Hand selecting and

inspecting is also time consuming and laborintensive.

Applications of vibratory feeders:

(a) Vibratory feeders are utilized in the pharmaceutical, automotive, chemical and mining

industries. Other industries include steel, glass, concrete etc.


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(b) These are used in chemical plants to control the flow of ingredients to the mixing tanks.

(c) Pulp and paper industry.

(d) These are used by water and sewage treatment plants in chemical additive handling.

(e) These are used in industries of rubber, textile, detergents, etc.

RECIPROCATING-TUBE HOPPER FEEDER

A reciprocating-tube hopper is illustrated in figure and consists of a conical hopper with a

hole in the center, through which a delivery tube passes. Relative vertical motion between the

hopper and the tube is achieved by reciprocating either the tube or the hopper. During the

period when the top of the tube is below the level of parts, some parts will fall into the

delivery tube. It is usual to machine the top of the tube at an angle such that a part restingacross the opening will fall clear and not block the opening as the tube is pushed upward

through the mass of parts. Care must be taken in choosing the angle of the conical hopper

because, if the angle is too small, parts may jam between the tube and the hopper.

CENTRIFUGAL HOPPER FEEDER

The centrifugal hopper feeder shown in figure is particularly suitable for feeding plain

cylindrical parts. In this device, the parts are placed in a shallow cylindrical hopper whose

base rotates at constant speed. A delivery chute is arranged tangentially to the stationary wallof the hopper, and parts adjacent to this wall that have become correctly oriented because of


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the general circulation pass into the delivery chute. No orienting devices are provided in the

hopper and, therefore, parts must be taken off in the attitude that they naturally adopt in the

hopper, as indicated in the figure.

Deepak Mahajan

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