60715137-Extra

7/29/2019 60715137-Extra

1/50

1.2.2 Different Types of Jaw Crusher

Jaw crusher can be divided into two according to the amplitude of

motion of the moving face. The different types of Jaw Crushers are:

1) Blake Type Jaw Crusher

In this the movable jaw is hinged at the top of the crusher frame so

that the maximum amplitude is obtained at the bottom of the crushing

jaws. Blake Crushers are operated by toggles and controlled by a pitman.

These are commonly used as primary crushers in the mineral industry.

The size of the feed opening is referred to as the ga pe . The opening at the

discharge end of the jaws is referred to as the set. The Blake crushers are

single or double toggle drives. The function of the toggle(s) is to move

the pivoted jaw. The retrieving action of the jaw from its furthest end of

travel is by springs for small crushers or by a pitman for larger crushers.

As the reciprocating action removes the moving jaw away from the fixed

jaw the broken rock particles slip down, but are again caught at the next

movement of the swinging jaw and crushed. This process is repeated

until the particle sizes are smaller than the smallest opening between the

crusher plates at the bottom of the crusher (the closed set). For a smooth

reciprocating action of the moving jaws, heavy flywheels are used in both

types of crushers. Blake type jaw crusher may be divided into two types.

[6]

7/29/2019 60715137-Extra

2/50

(a) Single toggle type: - In this the number of toggle plate is only one.

It is cheaper and has less weight compare to a double toggle type jaw

crusher. The function of the toggle(s) is to move the pivoted jaw.

(b) Double toggle type: - Here the number of toggle plate is two. Over

the years many mines have used the double-toggle style of crusher

because of its ability to crush materials; including mineral bearing oresthose were both tough and abrasive. While many aggregate producers

have used the overhead eccentric style. There are many factors that

should be considered when deciding which style would be best for your

application. For larger material crushing, always larger Blake type jaw

crushers are selected. The characteristics of this type of crusher are as

following

1. Larger, rough, blocky as well as sticky rock or ore lumps can be

crushed.

2. Reinforcement of the crusher is possible with the help of high

strength crusher frame to crush very hard rock or ore lumps.

3. It is very simple to adjust to prevent much of wear and also very easy

to repair,

4. Maintenance o the crusher is very easy.

7/29/2019 60715137-Extra

3/50

Single-Toggle Jaw Crusher

Double-Toggle Jaw Crusher

Fig.1.2. Types of Blake Type Jaw Crusher [43]

2) Dodge Type Jaw Crusher

The moving plate is pivoted at the bottom and connected to an

eccentric shaft. In universal crushers the plates are pivoted in the middle

so that both the top and the bottom ends can move. The movable jaw is

hinged at the bottom of the crusher frame so that the maximum

amplitude of motion is obtained at the top of the crushing jaws. They are

comparatively lower in capacity than the Blake crushers and are more

commonly used in laboratories.

7/29/2019 60715137-Extra

4/50

Fig.1.3. Dodge Type Jaw Crusher [6]

1.3 Major Components of a Jaw Crusher

Crusher Frame:

Crusher Frame is made of high welding. As a welding structure, it

has been designed with every care so as to ensure that it is capable of

resistant to bending stress even when crushing materials of extremely

hard.

Jaw Stock:

Jaw Stock is also completely welded and has renewable bushes,

Particular importance has been given to jaw Stock of a design resistant to

bending stresses. All jaw stocks are provided with a renewable steel

Alloy or manganese steel toggle grooves.

Jaw Crusher Pitman:

The pitman is the main moving part in a jaw crusher. It forms the

moving side of the jaw, while the stationary or fixed jaw forms the other.

It achieves its movement through the eccentric machining of the

7/29/2019 60715137-Extra

5/50

flywheel shaft. This gives tremendous force to each stroke.

Thus it appears this is just the name that was applied to this part. Pitman

is made of high quality steel plates and carefully stress relived after

welding. The Pitman is fitted with two renewable steel Alloy or

manganese steel toggle grooves housings for the bearings are accurately

bored and faced to gauge.

Manganese Dies in the Jaw Crusher:

The jaw crusher pitman is covered on the inward facing side with

dies made of manganese, an extremely hard metal. These dies often have

scalloped faces. The dies are usually symmetrical top to bottom and can

be flipped over that way. This is handy as most wear occurs at the

bottom (closed side) of the jaw and flipping them over provides another

equal period of use before they must be replaced.

Jaw Crusher Fixed Jaw Face:

The fixed jaw face is opposite the pitman face and is statically

mounted. It is also covered with a manganese jaw die. Manganese liners

which protect the frame from wear; these include the main jaw plates

covering the frame opposite the moving jaw, the moving jaw, and the

cheek plates which line the sides of the main frame within the crushing

chamber.

Eccentric Jaw Crusher Input Shaft:

7/29/2019 60715137-Extra

6/50

The pitman is put in motion by the oscillation of an eccentric lobe

on a shaft that goes through the pitman's entire length. This movement

might total only 1 1/2" but produces substantial force to crush material.

This force is also put on the shaft itself so they are constructed with large

dimensions and of hardened steel. The main shaft that rotates and has a

large flywheel mounted on each end. Its eccentric shape moves the

moving jaw in and out. Eccentric Shaft is machined out of Alloy Steel

Fitted with anti-friction bearings and is housed in pitman and dust proof

housing.

Jaw Crusher Input Sheave/Flywheel:

Rotational energy is fed into the jaw crusher eccentric shaft by

means of a sheave pulley which usually has multiple V-belt grooves. In

addition to turning the pitman eccentric shaft it usually has substantial

mass to help maintain rotational inertia as the jaw crushes material.

7/29/2019 60715137-Extra

7/50

Fig.1.4. Sectional view showing

Components of a Jaw CrusherToggle Plate Protecting

the Jaw Crusher:

The bottom of the pitman is supported by a reflex-curved piece of

metal called the toggle plate. It serves the purpose of allowing the

bottom of the pitman to move up and down with the motion of the

eccentric shaft as well as serve as a safety mechanism for the entire jaw.

Should a piece of non-crushable material such as a steel loader tooth

(sometimes called "tramp iron") enter the jaw and be larger than the

7/29/2019 60715137-Extra

8/50

closed side setting it can't be crushed nor pass through the jaw. In this

case, the toggle plate will crush and prevent further damage.

Tension Rod Retaining Toggle Plate:

Without the tension rod & spring the bottom of the pitman would just

flop around as it isn't connected to the toggle plate, rather just resting

against it in the toggle seat. The tension rod system tensions the pitman

to the toggle plate. The toggle plate provides a safety mechanism in case

material goes into the crushing chamber that cannot be crusher. It is

designed to fail before

the jaw frame or shaft is damaged. The seats are the fixed points where

the toggle plate contacts the moving jaw and the main frame.

Jaw Crusher Sides Cheek Plates:

The sides of the jaw crusher are logically called cheeks and they

are also covered with high-strength manganese steel plates for durability.

Jaw Crusher Eccentric Shaft Bearings:

There are typically four bearings on the eccentric shaft: two on

each side of the jaw frame supporting the shaft and two at each end of

the pitman. These bearings are typically roller in style and usually have

labyrinth seals and some are lubricated with an oil bath system. Bearings

that support the main shaft. Normally they are spherical tapered roller

bearings on an overhead eccentric jaw crusher.

7/29/2019 60715137-Extra

9/50

Anti-Friction Bearings are heavy duty double row self-aligned

roller-bearings mounted in the frame and pitman are properly protected

against the ingress of dust and any foreign matter by carefully machined

labyrinth seals. Crushing Jaws are castings of austenitic manganese steel

conforming to IS 276 grade I & II. The crushing jaws are reversible to

ensure uniform wear and tear of grooves.

Jaw Crusher Adjustment: Closed Side Opening Shims

Depending on the disposition of the material being crushed by the

jaw different maximum sized pieces of material may be required. This is

achieved by adjusting the opening at the bottom of the jaw, commonly

referred to as the "closed side setting". Shims (sometimes implemented

and a more adjustable or hydraulic fashion) allow for this adjustment.

[41]

CHAPTER -2

7/29/2019 60715137-Extra

10/50

L I T E R A T U R E R E V I E W

7/29/2019 60715137-Extra

11/50

2. LITERATURE REVIEW

Jaw crushers are used to crush material such as ores, coals, stone

and slag to particle sizes. Jaw crushers operate slowly applying a large

force to the material to be granulated. Generally this is accomplished by

pressing it between jaws or rollers that move or turn together with proper

alignment and directional force. The jaw crusher squeezes rock between

two surfaces, one of which opens and closes like a jaw. Rock enters the

jaw crusher from the top. Pieces of rock those are larger than the opening

at the bottom of the jaw lodge between the two metal plates of the jaw.

The opening and closing action of the movable jaw against the fixed jaw

continues to reduce the size of lodged pieces of rock until the pieces are

small enough to fall through the opening at the bottom of the jaw. It has

a very powerful motion. Reduction in size is generally accomplished in

several stages, as there are practical limitations on the ratio of size

reduction through a single stage.

The jaw crushers are used commercially to crush material at first in

1616 as cited by Anon [1].It is used to simplify the complex engineering.

Problem those were prevailing in Mining and Construction sector. An

important experimental contribution was made in1913; Taggart [2]

showed that if the hourly tonnage to be crushed divided by Square of the

gape expressed in inches yields a quotient less than 0.115 uses a jaw

crusher.

Lindqvist M.and Evertsson C. M. [3] worked on the wear in rock

of crushers which causes great costs in the mining and aggregates

industry. Change of the geometry of the crusher liners is a major reason

for these costs. Being able to predict the geometry of a worn crusher will

help designing the crusher liners for improved performance. Tests have

been conducted to determine the wear coefficient. The experiments have

been carried out using quartzite, known for being very abrasive.

Crushing forces have been measured, and the motion of the crusher has

been tracked along with the wear on the crusher liners. The test results

show that the wear mechanisms are different for the fixed and moving

liner. If there were no relative sliding distance between rock and liner,

would yield no wear. This is not true for rock crushing applications

7/29/2019 60715137-Extra

12/50

where wear is observed even though there is no macroscopic sliding

between the rock material and the liners. The predicted worn geometry is

similar to the real crusher. The objective of this work, where wear was

studied in a jaw crusher, is to implement a model to predict the geometry

of a worn jaw crusher.

DeDiemar R.B. [4] gives new ideas in primary jaw crusher design and

manufacture of Jaw crusher utilizing open feed throat concept, power

savings and automation features. Jaw

crushers with two jaw openings can be considered to be a completely

new design. Jaw crushers are distinguished by reciprocating and complex

movement of the moving jaw. Jaw crushers with hydraulic drives

produced in France and jaw crushers with complex movement of two-

sided jaws produced have advantages as well as a common shortcoming.

This is due to the discharge gap being almost vertical or sharply inclined

so that a large part of the material is crushed only to a size corresponding

to the maximum width of the gap between the jaws at the crusher exit. A

new design has a gently sloping gap between the movable and stationary

jaws .This causes material to move slowly and be subjected to repeated

crushing. In addition the movement of the movable jaw relative to the

stationary one is such that its stroke is equal both at the inlet and outlet

of the discharge gap when the eccentric moves in different quadrants.

The power consumption of this jaw crusher is low since the work of

crushing is distributed between two quadrants. The precrushed material

falls under its own weight onto the movable jaws which are lowered by

the movement of the eccentric through the third and fourth quadrants.

During this movement the material moved down slightly along the gapbetween the jaws and comes in contact with the movable jaws at

approximately the time when they are furthest removed from stationary

jaws. The material is again crushed as the eccentric continues to move

through the first and second quadrant. The material thus undergoes

repeated crushing when it passes through the gap between the jaws.

Efforts to intensify the crushing process and to increase throughput

capacity of crushers sometimes leads to interesting solutions of kinematic

systems. Analysis of crusher operation leads to the conclusion that

development of their design is proceeding both along the path of

7/29/2019 60715137-Extra

13/50

improved design and development of fundamentally new efficient

kinematic systems.

Russell A.R., Wood D. M. [5] helps in failure criterion for brittle

materials is applied to a stress field analysis of a perfectly elastic sphere

subjected to diametrically opposite normal forces that are uniformly

distributed across small areas on the sphere's surface. Expressions are

obtained for an intrinsic strength parameter of the material, as well as its

unconfined compressive strength. An expression for the unconfined

tensile strength is obtained by introducing an additional parameter

accounting for the micro structural features of the material. The

expressions indicate that failure initiates in the sphere where the ratio

between the stress invariant and the first stress invariant is a maximum.

Such a criterion does not coincide with the location of maximum tensile

stress. The expressions are used to reinterpret published point load test

results and predict unconfined compressive strengths. The configuration

of the point load test as well as surface roughness and elastic properties

of the pointer and samples are taken into account to

establish the size of the area on which the point loads act. The predictions

are in good agreement with measured values obtained directly using

unconfined compressive strength tests. It is concluded that the point load

test provides a more reliable estimate of the compressive strength than

the tensile strength.

Gupta Ashok and Yan D.S. [6] worked in design of jaw crushers

which impart an impact on a rock particle placed between a fixed and a

moving plate. The faces of the plates are made of hardened steel. Both

plates could be flat or the fixed plate flat and the moving plate convex.

The surfaces of both plates could be plain or corrugated. The moving plate

applies the force of impact on the particles held against the stationary

plate. Both plates are bolted on to a heavy block. As the reciprocating

action removes the moving jaw away from the fixed jaw the broken rock

particles slip down, but are again caught at the next movement of the

swinging jaw and crushed. This process is repeated until the particle sizes

are smaller than the smallest opening between the crusher plates at the

bottom of the crusher (the closed set). For a smooth reciprocating action

7/29/2019 60715137-Extra

14/50

of the moving jaws, heavy flywheels are used in both types of crushers.

Dowding Charles H. [7] designed jaw plates to reduce efforts to

decrease energy consumed in crushing have lead to consideration of

decreasing the weight of the swing plate of jaw crushers for easily crushed

material. This paper presents the results of an investigation of the

feasibility of using point load-deformation-failure (PDF) relationships

along with interactive failure of rock particles as a model for such a

weight reduction. PDF relationships were determined by point-loading

various sizes of materials: concrete mortar, two types of limestone,

amphibolites and taconite. Molling [7], who proposed this hypothetical

distribution, was only concerned with the total loading force. The

parameter which most controls the design of the swing plate is the load

distribution. Instrumentation of toggle arms in has since led to correlation

of measured with rock type. Ruhl [7] has presented the most complete

consideration of the effect of rock properties on Q and the toggle force.

His work is based upon the three-point loading strength of the rock,

which he found to be one-sixth to one eleventh the unconfined

compressive strength. He calculated hypothetical toggle forces based

upon the sum of forces necessary to crush a distribution of regular

prisms fractured from an initial cubical rock part icle. These approaches

involved both maximum resistance and simultaneous failure of all

particles and thus neither can lead to an interactive design method for

changing stiffness (and weight) of the swing plate. In this study point-

loading of cylinders are undertaken to model behavior of irregular rock

particles.

Berry P. et al [8] studied the laws of mechanics and constitutive

relations concerning rock breakage characteristics. The simulated results

are consistent with the general description and experimental results in

the literature on particle breakage. A descriptive and qualitative particle

breakage model is summarized as the following: at the first loading stage

the particle is stressed and energy is stored as elastic strain energy in the

particle. A number of randomly distributed isolated fractures are initiated

because of the heterogeneity.

Weiss N.L. [9] work is on the liner of a jaw crusher is an interface

7/29/2019 60715137-Extra

15/50

for analyzing the crushing force, on which the crushing force occurs, in

other words, the directly contact and the interaction between the material

and the liner occur there. So the interface has great effect on the crushing

feature of jaw crusher. The liner is one of the curves in the cross-section

of the couple plane, which is also given a definition as one of the coupler

curves in a four bar crank-rocker model.

Niles I. L. [10] showed that point-load failure of a sphere was

equal to that of a point-loaded ellipsoid. Therefore, ultimate point loads

on spheres will be approximately equal to ultimate point loads on

cylinders (or discs). For both the ellipsoids and the cylinders, the excess

volume outside the spherical dimensions does not change the circular

failure surface parallel to the smallest dimensions of the body. This

circular failure surface for the sphere and cylinder is shown by the

jagged lines on the two shapes. These authors and others also compared

disc and irregular particle point-load strengths from tests on dolomite,

sandstone and shale and found the point load strength of the disk and

irregularly shaped particles to be equal. Thus, the properties determined

from point-loading of discs or cylinders are appropriate for the point-

loading of irregular particles.

Georget Jean-Pirre and Lambrecht Roger [11] invented jaw

crushers comprising a frame, a stationary jaw carried by the frame a

mobile jaw associated with the stationary jaw and defining a crushing

gap therewith; an eccentric shaft supporting one end of the frame and a

connecting rod or toggle supporting the other mobile jaw end on the

crossbeam. The position of the crossbeam in relation to the frame is

adjustable to change the distance between the jaws i.e. the size of

crushing gap. A safety system permits the mobile jaw to recoil when the

pressure it exerts on the connecting rod exceeds a predetermined value,

for example because an unbreakable piece is in the crushing gap. In the

illustrated jaw crusher, the crossbeam is pivotally mounted on the frame

for pivoting about an axis parallel to the shaft and the safety system acts;

on the

crossbeam to prevent it from pivoting when the force applied by the

mobile jaw to the crossbeam remains below a predetermined value.

7/29/2019 60715137-Extra

16/50

Pollitz H.C.[12] presents invention concerns an improved design

of stationary and movable jaw plates for jaw type crusher which

minimizes warping of the jaws and increases their life more particularly

the present invention concerns an improved structure for mounting the

stationary jaw plate to the crusher frame and for increasing the rigidity

and life of both plates. Zhiyu Qin, Ximin Xu [13] indicated that the

relationship between the increasing rate of holdup and the material-

feeding rate were examined. From the results, the maximum crushing

capacity was defined as the maximum feed rate where holdup did not

change with time and remained at a constant value.

Qin Zhiyu [14] studied different positions of liners in the coupler

plane have different moving features, the motion of points along the

liners in the computing domain is quite different from that of them in the

straight-line coupler of the simple four bar crank-rocker model.

Therefore, it is necessary to consider motion differences caused by

different liner positions and their motion features to select a coupler

curve as the swing liner with good crushing character. Cao Jinxi [14]

worked on the certain domain, called the liner domain, of the coupler

plane is chosen to discuss the kinetic characteristic of a liner or a crushing

interface in the domain. Based on the computation and the analysis of the

practical kinetic characterist ic of the points along a liner paralleling to

the direction of coupler line, some kinematics arguments are determined

in order to build some kinetic characteristic arguments for the

computing, analyzing and designing.

Lytwynyshyn G. R [15] reported that the slow compression test

was the most efficient method of particle fragmentation with impact

loading being approximately 50% efficient, whilst the ball mill was

considered to be approximately 15% as efficient as the slow compression

test. Krogh undertook drop weight tests on small samples of quartz with

the impact speed in the range 0.64-1.9 m/s, but with constant impact

energy. It was found that the probability of breakage of each individual

particle was not influenced by impact speed nor was the size distribution

of the fragments produced.

Gabor M. Voros [16] presents the development of a new plate

stiffener element and the subsequent application in determine impact

loads of different stiffened plates. In structural modeling, the plate andthe stiffener are treated as separate finite elements where the

7/29/2019 60715137-Extra

17/50

displacement compatibility transformation takes into account the torsion

flexural coupling in the stiffener and the eccentricity of internal forces

between the beam plate parts. The model

becomes considerably more flexible due to this coupling technique. The

development of the stiffener is based on a general beam theory, which

includes the constraint torsional warping effect and the second order

terms of finite rotations. Numerical tests are presented to demonstrate the

importance of torsion warping constraints. As part of the validation of

the results, complete shell finite element analyses were made for

stiffened plates.

Kadid Abdelkrim [17] carried out investigation to examine the

behavior of stiffened plates subjected to impact loading. He worked to

determine the response of the plates with different stiffener

configurations and consider the effect of mesh dependency, loading

duration, and strain-rate sensitivity. Numerical solutions are obtained by

using the finite element method and the central difference method for the

time integration of the non-linear equations of motion. Special emphasis

is focused on the evolution of mid-point displacements, and plastic strain

energy. The results obtained allow an insight into the effect of stiffener

configurations and of the above parameters on the response of the plates

under uniform blast loading and indicate that stiffener configurations and

time duration can affect their overall behavior.

Jaw plates used in modern crushing operations are fabricated

almost exclusively from what is generally known as Hadfield manganese

steel [19], steel whose manganese content is very high and which

possesses austenitic properties. Such jaw plates are not only extremely

tough but are also quite ductile and work-harden with use. Under the

impact of crushing loads flow of the metal at the working surface of

the plate occurs in all directions. This flow occurs chiefly in the

central area of the plate, particularly the lower central area, because the

lower portion of the plate does very substantially more work than the

upper portion. This is particularly true in case of the stationary jaw,

which, as well known receives the greater wear in operation. If the

flow is not compensated for, the jaw will distort or warp, particularly

7/29/2019 60715137-Extra

18/50

in its more central area, so that it will no longer contact its seat. Thus

crushing loads will cause it to flex with consequent decrease in crushing

efficiency and increase in wear both of the jaw itself and particularly its

seat.

CHAPTER -3

T H E O R E T I C A L A N A L Y S I S A N D D A T A C O L L E C T I O N

7/29/2019 60715137-Extra

19/50

3. THEORETICAL ANALYSIS AND DATA COLLECTION

3.1 Introduction to Kinematics of the Machines

3.1.1 Study of Machines:

In general the study of a Machine involves problems of three distinct kinds. We may first

of all consider from a geometrical point of view the motion of any part of the machine with

reference to any other part, without taking account of any of the forces acting on such parts. Or,

the action of the forces impressed on the parts of the machine, and of the forces due to its own

inertia or to the weight of its parts, may be dealt with, and the resulting transformations of energy

may be determined. A third branch of the theory of machines treats of the action of these loads

and forces in producing stresses and strains in the materials employed in the construction of the

machine, and discusses the sizes, forms, and proportions of the various parts which are required

either to insure proper strength while avoiding waste of material, or to make the machine capable of

doing the work for which it is being designed.

The science dealing with the first-named class of problem is termed the Kinematics of

Machines, which we may define as being that science which treats of the relative motion of the

parts of machines, without regard to the forces producing such motions, or to the stresses and

strains produced by such forces.

3.1.2 Kinematics of Machines:

With this limitation, in the case of almost all bodies forming portions of machines, it is

possible to neglect any deformation they may undergo in working, and in studying the Kinematics

of Machines we may at once apply to machine problems the results obtained by the study of the

motion of rigid bodies. Important exceptions will present themselves to the reader's mind; for

example, ropes, belts, and springs cannot be considered kinematically as being rigid, and many

mechanical contrivances involve the use of liquid or gaseous material. Such cases as these will be

considered later.

By the term Machine we may understand a combination or arrangement of certain portions

of resistant material, the relative motions of which are controlled in such a way that some form of

available energy is transmitted from place to place, or is transformed into another desired kind.

This definition includes under the head of Machines all contrivances which have for their object

the transformation or transmission of energy, or the performance of some

7/29/2019 60715137-Extra

20/50

particular kind of work, and further implies that a single .portion of material is not considered as a

machine. The so-called simple machines in every case involve the idea of more than one piece of

material.

A combination or arrangement of portions of material by means of which forces are

transmitted or loads are carried without sensible relative motions of the component parts is called a

structure.

The term Mechanism is often used as an equivalent for the word Machine. It is, however,

preferable to restrict its use somewhat, and to employ the word to denote simply a combination of

pieces of material having definite relative motions, one of the pieces being regarded as fixed in

space. Such a mechanism often represents kinematically some actual machine which has the same

number of parts as the mechanism with the same relative motions. The essential difference is that

in the case of a machine such parts have to transmit or transform energy, and are proportioned and

formed for this end, while in a mechanism the relative motion of the parts only is considered. We

may look upon a mechanism, then, as being the ideal or kinematic form of a machine, and our

work will be much simplified in most cases if we consider for kinematic purposes the mechanism

instead of the machine. Such a substitution is also of the greatest service in the comparison and

classification of machines; we shall find in this way that machines, at first sight quite distinct, are

really related, inasmuch as their representative mechanisms consist of the same number of parts

having similar relative motions, and only differing because a different piece is considered to be

fixed in each case.

3.1.3 Classification of Mechanisms:

In attempting to classify mechanisms, which are made up of various kinds of links and

involve so many kinds of pairing, we are impressed with the magnitude and complexity of the

task. It may be said, in fact, that up to the present no wholly satisfactory kind of machine

classification has been proposed to consider mechanisms under three heads.

1. Those involving only plane motion. These may be called shortly Plane Mechanisms, and

form by far the most important and numerous classes.

2. Mechanisms involving spheric motion, or, more briefly, Spheric Mechanisms.

3. Chains the relative motion of whose links is neither plane nor spheric, but of greater

complexity.

It is, however, to be understood that a mechanism of the third kind may contain certain

links whose motion is plane or spheric, while any of them may include examples of both lower

7/29/2019 60715137-Extra

21/50

and higher pairing.

A well-known instance of a spheric mechanism is Hookes joint, the characteristic property

of such chains being that the axes of the turning pairs they contain meet in a point. In the third

class the most common examples are screw mechanisms.

There is another method of classifying machines according to their geometrical properties,

and according to the methods necessary for determining the various virtual centres of their links.From this it follows that in such mechanisms, having given the whole mechanism in one position,

we can find geometrically all its other possible positions, and: the virtual centre of each link

relatively to every other. Mechanisms not possessing these properties belong to higher orders, and

are of comparatively infrequent occurrence.

3.1.4 Four-Bar Linkage

A four-bar linkage or simply a 4-bar or four-bar is the simplest movable linkage. It consists

of four rigid bodies (called bars or links), each attached to two others by single joints or pivots to

form a closed loop. Four-bars are simple mechanisms common in mechanical engineering machine

design and fall under the study of kinematics. If each joint has one rotational degree of freedom

(i.e., it is a pivot), then the mechanism is usually planar, and the 4-bar is determinate if the

positions of any two bodies are known (although there may be two solutions). One body typically

does not move (called the ground link, fixed link, or the frame), so the position of only one other

body is needed to find all positions. The two links connected to the ground link are called grounded

links. The remaining link, not directly connected to the ground link, is called the coupler link. In

terms of mechanical action, one of the grounded links is selected to be the input link, i.e., the link

to which an external force is applied to rotate it. The second grounded link is called the follower

link, since its motion is completely determined by the motion of the input link.

Grashofs law is applied to pinned linkages and states; The sum of the shortest and longest

link of a planar four-bar linkage cannot be greater than the sum of remaining two links if there is

to be continuous relative motion between the links. Fig3. 1 shows the possible types of pinned,

four-bar linkages.

7/29/2019 60715137-Extra

22/50

Fig.3.1 Types of four-bar linkages, s = shortest link, = longest link

3.2 Jaw Crusher as a Crank- Rocker Mechanism:

Mechanism of a typical single toggle jaw crusher can be treated as a crank-rocker

mechanism of a four-bar linkage having; frame as a fixed link, crank as an eccentric shaft, liner as

coupler and toggle plate as follower as shown in the Fig3.2. The calculation parameters of the

PE400600 are shown in Table 3.1.

r(mm) l(mm) k(mm)

12 1085 455

Table 3.1: PE400* 600 Jaw Crusher Calculation Parameters

AB = Crank (r)

BC = Length of the liner (l)

CO = toggle plate length (k)

AO = frame or fixed link

Toggle plate one end is connected to frame (O) and other end is connected to themovable jaw(c) as shown in the Fig.3.2.The angles and represents the angle of liner and crank

making with vertical.

Dimensions and operating parameters when considering the jaw crusher of Fig.3 .2, there

are variables of the feed that define the important machine dimensions.

The feed particle sizes of interest are:

1 .The size of particle that enters the crusher

2.The size of particle that can be nipped

3.The size of particle that can fall through the chamber at any time

4.The size of particle that can fall through the chamber when the jaws are open as wide as

possible.

7/29/2019 60715137-Extra

23/50

The dimensions defined by those particle sizes are (Fig.3.2 ):

1 .The gape - the distance between the jaws at the feed opening

2. The closed side set (CSS) - the minimum opening between the jaws during the crushingcycle (minimum discharge aperture)

3. The open side set (OSS) the maximum discharge aperture 4.The throw the

stroke of the swing jaw and the difference between OSS and CSS.

Fig.3 .2 Jaw Crusher sketch( 12)

3.3 Choosing the Points along the Liner for Computing:

A liner of jaw crusher is an interface for analyzing the crushi ng force, on which the

crushing f orce occurs, in other words, the directly contact and the interaction between the

material and the liner occur there. So the interface has great effect on the crushing feature of jaw

crusher. The liner is one of the curves in the cross- section of the couple plane, which is also

fourbar crank-

given a definition as one of the coupler curves in a rocker model. Since different positions of

liners in the coupler plane have different moving features, the motion of points along the li ners in

the computing domain is quite different from that of them in the straight-line coupler of the simple

fourbar crank-rocker model. Therefore, it is necessary to consider motion

liner positions and their motion features

differences caused by different to select a coupler curve

as the swing liner with good crushing character.

-rocker model, the system

Based on the fourbar crank sketch of jaw crusher for calculating is shown in Fig.3 .3. The

global static coordinate is XOY and the dynamic coordinate is UCV. Although a real shape and

position of a fixed working liner is usually determined by a

7/29/2019 60715137-Extra

24/50

suspension point of the jaw crusher, computation of a liner will be done on the one of chosen

curves in the liner domain. Thus with different position on the liner, each computing point on it

liners will arrive at the limit position at different time. However it is well known that a practical

crushing force exerted on fractured material is in the normal direction of the liner. The normal

direction of each point in the liner changes in one operation cycle. So a distance between the limit

positions in normal direction of those points is quite different from that of the displacement of

horizontal motion.

In order to describe the kinematic characteristics of the points in the liner domain, the

single toggle jaw crusher PE400x600 is taken as example to compute and analyze the distributed

kinematic characteristic. The calculation parameters of the PE400600 are shown in Table3.1. Inorder to illustrate the motion of the points in liner domain, it is needed to define the liner domain.

One plane along the coupler BC is selected and is divided into 10 equal parts as shown in the Fig.

3.3. So there are 11 points selected to be calculate in the V direction for a certain U and the

eccentric shaft is rotating at a speed of 300rpm. The position of the eccentric shaft with respect to

global co-ordinates XOY is A(a , b) is located at a=45.3 & b=815.7. With the points for

computing and the liner domain chosen as above mentioned, computing results are shown in

follows.

Fig.3 .3 Points track along the liner

7/29/2019 60715137-Extra

25/50

3.4 Movement Computation and Feature Analysis of Points:

The mechanism of th e jaw crusher is shown in Fig.3.2; g iven the rotation direction of the

crank AB is clockwise.

Where = Crank angle made by vertical

= Angle betw een two plates 900 and

2 2 2m n m n nm( ) ( 1 ) ( 1 )+ +sin = (3.1)

cos= + m n sin

(3.2)

2 2 2 2 2

abr l k rab 2 ( s i n c o s ) + + + +m = (3.3)

arsinn = _______

b rcos .. (3.4)

By rotating crank () from 000 -3600 the variation of nip angle ( ) is shown in Table 3.2.

0 36 72 108 144 180 216 252 288 324 360

18.898 19.473 19.994 20.249 20.146 19.742 19.192 18.696 18.43 18.501 18.898

Table 3.2: variation of nip angle with crank angle

dynamicGiven the position of any point in coordinate UCV is (u, v) and in global

coordinate XOY is (x, y) as shown in Fig.3.4.

As mentioned above =BC lA B r =

By observing Fig. A K = r s i n ( 9 0 )

B K = r c o s ( 9 0 )

And LP'=uc o s = PP'us i n

=MN a BK

= a r s i n

=N L ( B C L C ) s i n

= ( l v ) s i n

Fig.3.4 Point consideration in dynamic coordinate

22

n + 1

7/29/2019 60715137-Extra

26/50

A P = +A K K ' P

=K ' P B N P P '

+A P =A K B N P P '

AP= rc o s + (l v) c o s u s i n

Therefore horizontal displacement:

x =M N + +N L L P '

=x a r s i n + ( l v ) s i n + uc o s

And vertical displacement:

= b AP

=y b r c o s ( l v +) c o s us i n .. (3.6)

By rotation of the crank for one complete cycle, the variations of horizontal and vertical

displacements for the 11 points along the liner are shown in Fig.3.5 & Fig.3.6.

Fig.3.5 Horizontal Displacements Fig.3.6 Vertical displacements

The track of the sixth point is magnified and shown in Fig.3.7. The displacement variations

of the sixth point are shown in Fig3.8 & Fig.3.9. By observing the Fig.3.7, that the path of any point

on the liner is analogous to an ellipse.

7/29/2019 60715137-Extra

27/50

Fig.3.7 6th Point Track Fig.3.8 6th Point horizontal Fig.3.9 6th Point Vertical

Displacement Displacement

And the velocity of the points can be express as following equations:

d r a l l b( s i n ) c o s ( c o s ) s i n+~ + ~Since (3.7)= ~d l a r b r ~ +

s i n ( c o s )

Velocity in X-direction (VX) can be expressed with respect to crank rotation asdx ~ ~~_______~

d x dv =____ = ~X ~~ ~ ~ ~dt ~ ~

d d t~ ~

d u l v a r =~ ~ ++

( c o s ( ) s i n s i n )~ ~d d dv l v r uX( ) c o s c o s s i n ~= (3.8)

~ d d

The horizontal velocity variation for 11 points along the liner or swinging jaw plate

relative to the angle parameter is shown in Fig.3. 10.

Fig.3.10 Horizontal velocities

7/29/2019 60715137-Extra

28/50

And velocity in Y-direction (Vy) can be expressed with respect to crank rotation asd x dv =_______= ~X~ ~ ~ ~ ~

dt~ ~d d t

~ ~d u l v a r = ~ ~ + +

( c o s ( ) s i n s i n )~ ~d

~ ~d dv l v r uY ( ) s i n s i n s i n= + + ~

~ d d

The vertical velocity variation for 11 points along the liner or swinging jaw plate

relative to the angle parameter is shown in Fig. 3.11.

Fig.3.11 Vertical velocities

It can found that velocity in U-direction (vu) and velocity in V- direction (vv) as shown in

equations 3.10 & 3.11.

U

= +( ) c o s (

~ d

)

~

~ (3.10)

V v u r (3.11)

It is shown in equation 3.11 that the point with the same V component has the same

velocity component in the U direction, i.e., the U component has no effect on the velocity

component in the U direction. The variation of the velocity component in U direction relative to

the angle parameter is shown in Fig.3.12. It is obvious that the amplitude of the velocity

(3.9)

7/29/2019 60715137-Extra

29/50

variation is minimal for the points at the suspending point zone. The variation of the initial phase

has a certain law.

Fig. 3.12 U-directional Velocities

It is shown in equation3.12 that the point with the same U component has the same velocity

component in the V direction. In other words the V component has no effect on the velocity

component in the V direction. The variation of the velocity component in V-direction relative to

angle is shown in Fig.3.13. It is obvious that the amplitude of the velocity variation is decreasing

with the decreasing U component. The variation of the initial phase has a certain law.

Fig.3. 13 V-directional Velocities

Therefore the accelerations along the X direction (ax) and Y direction (ay) can also be found

as follows.

d v

~

~~~

X

d t ~ ~

7/29/2019 60715137-Extra

30/50

~ 2 2

d d ~ ~[] [ ]() c o s s i n ( ) s i n

c o s s i nl v u l v u r

~ ~ + +d d2 ~ ~ ~~

=Ydvddv ~ ~~ ~Ya =~

Ydt ~~ ~ ~ ~~ ~

d d t

d d d~ ~ 2= ~ ~ + +l v r ud d d~ ~

a=

~ 2 2d d

~ ~ [] [] ()ss()ssinsl v i n u c o l v c o u r c o+ + ~ ~ + .. (3.13)

Equation 3.12 and 3.13 shows the horizontal and vertical accelerations. Fig.3.14. and Fig.3.

15 represents the variation of accelerations in horizontal and vertical directions relative to the

crank angle varying from 00- 3600.

Fig.3. 14 Horizontal accelerations Fig.3. 15 Vertical accelerations

Equation 3.14 and 3.15 shows the accelerations in U-direction and V-direction. Fig.3.16.

and Fig.3.17 represents the variation of accelerations in U-direction and V-direction relative to the

crank a n g l e .

~~2

a=

.. (3.12)

7/29/2019 60715137-Extra

31/50

dv U= Ud v d~ ~~ ~

a U = ~

dt ~~ ~ ~ ~ ~ ~d d td d d~ ~ 2= ~ ~ + +l v r ud d d

~ ~

2~ ~ ~ ~d d 2a l v r = + + + ~ ~ ~U 1 ( ) s i n ( ) (3.14)~ ~ ~~

d d= Vd v d

dv ~ ~~ ~Va = ~Vdt ~~ ~ ~ ~ ~ ~

d d t

d d

~ ~ 2=~ ~ + +

u r s i n ( )d d

~ ~

2

(3.15)

Fig. 3.16 U-directional accelerations Fig.3.17 V-directional accelerations

7/29/2019 60715137-Extra

32/50

3.5 Squeezing Process & Particle Breakage

3.5.1 Fractured Size Distribution:

With the energy intensity increasing, there are three fracture mechanisms under

compression condition, as is shown in Fig.3.19. The breakage process due to the point contact

loading that occurs between the plates of a jaw crusher and a particle is illustrated in Fig.3.18. The

particle fracture mechanism in jaw crusher chamber is the mixture of the cleavage and the

abrasion. The abrasion fracture is caused with the localized too much energy input to the area

directly under the loading points and the friction between the jaw plates and the particle. The

areas directly below the loading contacts fail in compression producing abrasion fracture.

Abrasion can be thought as type of shatter fracture.

Fig. 3.18 Fracture caused by compression crushing [12] Fig.3.19 Particle fracture mechanism

The distribution of the particle sizes after fracture is dependent on the fracture mechanisms

occurring as a result of particle loading. For a given material, as particle size decreases strength

increases. This is due to the distribution of flaws within the material. Fracture initiates from the flaw

independently of all other flaws within the particle. Since the mechanisms of fracture also control

the distribution of progeny particle sizes and specific fracture mechanisms produce specific

fragment size. The energy criterion states that enough potential energy must be released in order

to overcome a materials resistance to crack propagation, requiring an increase in the work done

by external forces acting on the material. This is the amount of input energy to reducing the size

of particle. The amount of size reduction or the size distribution resulting from fracture is

dependent upon the presence and distribution of cracks.

7/29/2019 60715137-Extra

33/50

3.5.2 Squeezing Process:

In the common sense the nipped particle should be compressed and failed in tension stress

in the jaw crusher chamber. But in practice a sliding motion between the jaw plates and the particle

is inevitable. It is because that the moving jaw has the vertical movement relative to the fixed jaw

during the squeezing process. Sometimes sliding is accompanied with rolling motion of the

particle, which is determined by the geometry of the particle and the chamber. Because the sliding

motion between the moving and fixed jaw plates and the particle is a key factor to the jaw plates

wear, it is necessary to analyze this process.

The force on the particle during the squeezing process is shown in the Fig.3.20. Since the

horizontal and the vertical velocities of the moving jaw are variable during the squeezing process,

the forces on the particle are also variable in different stages in the crushing chamber. When the

component of the vertical velocity in the moving jaw plate direction is bigger than that of the

horizontal velocity in the same direction, the forces on the particle are shown in Fig.3.20 (a).

When the component of the vertical velocity in the jaw plate direction is smaller than that of the

horizontal velocity, the forces on the particle are shown in Fig.3.20 (b). Because the gravitational

force is much smaller than others, it can be ignored.

Where N1 ,

N2 represents the normal reactions of the moving and fixed jaw plates on thecrushing material and f1, f2 represents the frictional force between the jaw plates and the crushing

material.

The angle = 900- Nipping angle

(a) (b)

Fig.3.20 Forces on particle during crushing

7/29/2019 60715137-Extra

34/50

Considering equilibrium for Fig (a)

Equilibrium in horizontal direction:

=N1

sinf

1

cosN

2

0 (3.16)Equilibrium in vertical direction:

=N1cos+f1 si nf 20 (3.17)

N1 cos+N1s i n ' N2= 0 (3.18)

Given that the slide first takes place between the particle and the moving jaw plate. The

friction coefficient is.

=f1 N1 (3.19) The

friction coefficient between the particle and the fixed jaw plate will be

=f2 'N2 (3.20) By

equations (3.16) & (3.19)

N1sinN1 cosN= 20 (3.21)

N2 =N1(s i n c o s ) (3.22) From

equation (3.18)

co () s s i n+'______________________ 0=___________________>

() s i n c o sco ()

s sin + = '

. . (3.24)() s i n c o s

2 c o s c o s 0 =