LINEAR VIBRATORY CONVEYOR

This invention relates to a linear vibratory conveyor.

Linear vibratory conveyors are used to carry all manner of bulk

materials.

These are usually conveyed horizontally, but some inclination to

the vertical may also be involved.

Some well-established drives exist which include electro¬

magnetic, electro-dynamic, pnue atic, hydraulic and combination

arrangements.

This invention, although applicable to any method of drive,

has been conceived especially to overcome problems associated

with an electro- magnetic method.

Figure 1 shows a typical linear vibratory conveyor in current

use.

Referring to Figure 1 , a typical conventional system has a mass

associated with the conveyor trough and its carriage, called the

active mass 1.

This is connected to the base, called the reactive mass 2, by

leaf springs or cantilever springs 3. These springs are usually

inclined to the vertical as illustrated to give the required

conveyor motion.

The typical vibratory drive 4 is usually arranged to produce a

vibratory force between the active mass and the reactive mass

and if the reactive mass is much larger than the active mass then

the oscillation or vibration is largely taken up by the active

mass. In this manner the conveyor trough and carriage is

subjected to the oscillation or vibration whilst the base

vibrates to a much smaller degree, and being mounted on shock

absorbers 5, undersirable transmission of the vibrations to the

surrounding area is reduced. Typically the oscillation used may

be at, or near the resonant frequency.

If electro-magnetic drives of this type having an air gap 6 are

employed for larger linear vibrating conveyors, there is a

conflict between having sufficient air gap to allow for the

required oscillatory displacement, and achieving a small enough

air gap to obtain the power required for the oscillation

without having to resort to the use of larger magnets and larger

1mput powers.

In regard to the typical linear vibratory conveyor illustrated

1n Figure 1, the following observations are made because of

their significance for the invention

(a) the active mass 1 and reactive mass 2

vibrate on a line through their centres

of gravity about a fixed point situated

between the two masses.

(b) There is a null point on the cantilever

springs 3, that is, a point which remains

stationary with respect to the ground.

(c) The position of this point on the cantilever

spring 3, depends on the ratio of the masses used

for the active mass and for the reactive mass.

(d) On the other hand the inclination to the vertical

of the surface of the springs in the vadnlty of

the null point will be constantly changing during

one cycle of oscillation.

In order to describe the operation of the linear vibrating

conveyor which incorporates the invention, a specific embodiment

of the invention will now be described by way of example with

reference to Figures 2 and 3.

Figure 2 illustrates by means of a simple diagram, the

disposition of the reactive mass 2 with respect to the active

mass 1 and the spring system which provides the interconnection

between these masses. This spring system consists of a set of

cantilever springs 3 joined to the active mass by spring

fixings and another set of cantilever springs 4 joined to the

reactive mass 2 by means of spring fixings and inclined at the

required angle to the vertical.

These sets of cantilever springs are joined together by means

of their common connection to the flat sections 5.

Figure 3 illustrates one example of a practical linear

vibratory conveyor which embodies the invention. The reactive

mass 2 is composed of two side pieces one on each side of the

spring system which are joined together by means of the channel

sections 8, together with additional sections 1f this is

required for strength. The illustration shows a side view of the

linear vibratory conveyor with the nearest of the side

pieces of the reactive mass 2 removed.

The sets of springs 3 and 4 are Joined together by flat sections

of material 5.

The electro-magnetic drive shown is a double system operating

in pull-pull, with the energised sections attached to the

reactive mass 2 and with the armature 1 sections, attached to

each of the flat sections 5, but alternatively the energised

sections may be attached to the flat sections 5 and the armature

I sections attached to the reactive mass.

There may be other rows of springs in addition to the two rows

shown.

The electro-magnetic drive may be a single system having one

energised section pulling on one armature I section, in which

case one of the two illustrated will be absent.

The electro-magnetic drive may be other than the type

illustrated.

The drive may be other than electro-magnetic.

The weight of the reactive mass on the cantilever springs 4

causes a small but additional stress in these springs. This can

be removed by allowing the reactive mass to rest on ordinary

compression springs inserted between the reactive mass and the

base.

One of the principle features of this linear vibratory conveyor

is that the active 1 and the reactive mass 2 are interconnected

not by one set of cantilever springs but by the use of two sets

of cantilever springs 3 and 4 Joined together through their

common connection to the flat sections of material 5.

When the linear vibratory conveyor is in action the null point on

the cantilever springs system will normally be designed to be

at, or close to, the junction of the springs 5. This is

achieved by the correct design of the cantilever springs 3 and 4

in relation to each other and in relation to the size of the

masses 1 and 2 and fulfulling a number of simultaneous

conditions. The correct design also achieves a minimum

change in the inclination to the vertical of the springs where

they make the common connection with flat section 5.

The design obtains that one set of cantilever springs

restrains the other set of cantilever springs in such a manner

as to closely maintain the same position and inclination to

the vertical at their Junction with the flat section 5, to that

which occurs statically.

Therefore the spring fixings normally present to restrain the

end of the springs to the required inclination to the vertical

are rendered redundant. For this reason, this linear vibration

conveyor is simple and easy to manufacture and much less

expensive than some other linear vibratory conveyors which have

the same objectives.

Because the position and angle of the flat section 5 is

maintained virtually constant whilst the masses are oscillating,

this flat section 5 may be used advantageously to directly

connect the linear vibratory conveyor to the ground or

sub-structure.

This may be achieved with or without a degree of shock

absorbing material , depending on the balance of the forces in

the system. This is illustrated in Figures 3, 4 and 5.

The electro-magnetic drive 7 may be applied between the active

mass 1 and the reactive mass 2 as in the conventional linear

vibratory conveyor.

Alternatively as shown by example in Figures 3, 4 and 5 the

electro-magnetic drive may be applied between the reactive mass

2 and the flat sections 5 where the springs are Joined together

or between the reactive mass 2 and the ground or sub-structure.

This allows the electro-magnetic drive to operate with smaller

magnetic air gaps or air gap 6.

In the conventional linear vibratory conveyor the air gap must

be sufficient to allow for the total movement between the

active mass and the reactive mass which means the movement of

the top carriage plus the movement of the reactive mass. In the

linear vibratory conveyor examples 1n F1g 3, 4 and 5 the air

gap need only be sufficient to allow for the movement of the

reactive mass. The invention therefore provides a solution to

the problem stated in the second paragraph of page 2 in that 1t

permits the use of smaller magnetic air gaps or air gap for the

electro—magnectic drive.

The examples illustrated in Figures 2, 4 and 5 are linear

vibratory conveyors supported on the ground or sub-structure

by means of the flat sections 5. It is sometimes preferable to

support these conveyors by means of the reactive mass, that is,

the reactive mass is connected to the ground or sub structure

through the medium of shock absorbers and this is therefore an

alternative to that illustrated in Figures 3, 4 and 5 but an

alternative that still maintains all the benefits of the

smaller magnetic air gaps or air gap.

Figures 4 and 5 illustrate further examples of a practical

linear vibratory conveyor which embody the invention-

The description and operation for these examples are exactly

the same as for the example illustrated in Figures 3 and

presented on pages 3, 4, 5 and 6 and must be read as such, with

the simple exception that the attachment of the section of the

electro-magnetic drive to the flat section 5 is achieved in a

different manner.

In Figure 4, the armature I sections are connected to the flat

sections 5 by means of the two slats 9, one on each side of the

spring system, or by other means. The diagram is drawn with the

nearest slat removed. The slat on the far side is shown

interconnecting the flat sections 5 of the two rows of springs on

either side of the magnetic drive, but these slats may also

interconnect all the other flat sections 5 that may be used.

The energised sections of the electro-magnetic drive are attached

to the reactive mass 2.

In figure 5 the energised sections of the electro-magnetic

drive are connected to the flat sections 5 by means of the two

slats 9, one on each side of the springs system, or by other

means.

The diagram is drawn with the nearest slat removed. The slat on

the far side is shown interconnecting the flat sections 5 of

the two rows of springs on either side of the electro-magnetic

drive, but these slats may also Interconnect all the other flat

sections 5 that may be used. The armature I sections of the

electro-magnetic drive are attached to the reactive mass 2.

This arrangement allows the electrical connection to the drive

to suffer little or no vibration.

In Figure 4 and 5 the electro-magnetic drive illustrated is a

double system, instead the electro-magnetic drive may be a

single system having one energised section pulling on one

armature I section, 1n which case one of the two systems

illustrated will be absent.

The weight of the reactive mass on the cantilever springs 4

causes a small but additional stress in these springs.

This can be removed or alleviated by allowing the reactive mass

to rest on ordinary compression springs 10, these being inserted

between the reactive mass 2 and the slats 9.

Each of the examples of linear vibratory conveyor illustrated

1n Figures 3, 4 and 5 benefit from being driven constantly at

their resonant frequency even when this changes due to load.

This is achieved by using a power imput, the frequency of which

is derived from its own natural movement.

The electro-magnetic drive may be other than the type

illustrated.

The drive may be other than electro—magnetic.

The illustration in figure 6 shows another embodiment of the

system of cantilever springs and the masses which they

interconnect, which constitutes the invention, but in which the

interconnecting springs are not parallel. The Springs 4 may be

set at another angle to that of the springs 3 and may be

conveniently positioned vertically as illustrated in figure 6. A

modest reduction in performance may result from this, but in

some instances the vibrator is easier to manufacture.

As a quite separate consideration the reactive mass may be

positioned between the two sets of springs, if there is an even

number of springs per row, instead of being divided into two

pieces, one on each side of the springs.

The embodiments of the invention shown in figures 3, 4 and 5, may

incorporate the spring system shown in figure 6, instead of that

which is shown. Also in these examples the reactive mass may be

positioned between two sets of springs Instead of being divided

into two pieces, one each side of the springs.

In all these embodiments the electro-magnetic drive, if used, may

be positioned to operate horizontally or closer to the

horizontal, instead of being inclined as illustrated. The drive

may be other than electro magnetic.

The illustration in figure 7 shows another embodiment of the

system of cantilever springs and the masses 1 and 2 which they

interconnect, which constitutes the invention, but which is part

of a hybrid arrangement of springs, that is, conventional

cantilever springs II are also used to interconnect the masses 1

and 2. This reduces the number of components and in some

examples makes the vibrator easier to manufacture.

The illustration in figure 7 shows two rows of each type of spring connection as an example but other combinations may be used and

in any order, with one or more row of springs being the

cantlever spring arrangement which constitutes the invention. The embodiment of the invention shown in figures 3, 4 and 5 may

incorporate the type of spring system illustrated in figure 7 and

described in the previous paragraph, instead of that which is

shown in figures 3, 4 and 5, or using that illustrated in both

- figures 6 and 7. In these examples the reactive mass may be positioned between the springs instead of being divided into two pieces one each side of the springs.

Other electro-magnetic drives may be used, or the drive may be other than electro magnetic.