Abstrict Apparatus for crushing swarf and like materials in which the material
to be crushed is received in a supply hopper which includes sensing
switch means responsive to material in the hopper reaching a selective
level for enabling a control circuit which controls operation of
the crusher.
Claims What is claimed is:
1. Apparatus for crushing swarf and like materials comprising:
a crushing chamber for the material to be crushed, said crushing
chamber having a loading opening to receive the material to be crushed
and having means for discharging crushed material;
crushing means disposed within said crushing chamber;
motor means operable for driving said crushing means to effect
crushing of material within said crushing chamber;
a supply hopper for receiving and storing material to be crushed,
disposed above said crushing chamber and formed by sidewall means
defining an open top and an open bottom communicating with the loading
opening of the crushing chamber;
electrical control circuit connected to said motor means for controlling
the operation thereof; said electrical control circuit including
a normally open switch means having a pair of contacts and responsive
to material in said hopper reaching a selected level for enabling
said electrical control circuit;
at least a portion of said switch means being disposed internally
of and supported within said hopper and extending about the periphery
thereof, and one of said switch contacts being disposed along the
inner surface of said sidewall means and normally electrically insulated
from the other of said switch contacts;
said one switch contact being positioned for engagement by material
filling said hopper as aforesaid, and the surface area of said switch
portion being sufficient to insure said switch means responding
to material filling said hopper as aforesaid;
whereby said switch is closed in response to said engagement of
said one switch contact by material in said hopper for enabling
said control circuit.
2. Apparatus as claimed in claim 1 wherein:
said one contact includes a band of electrically conductive material
supported on said inner surface of said sidewall means.
3. Apparatus as claimed in claim 2 wherein:
said one contact is a single band of conductive material extending
substantially around the entire periphery of the inner surface of
said sidewall means.
4. Apparatus as claimed in claim 3 wherein:
said hopper sidewall means is electrically conductive and comprises
the second of said switch contacts.
5. Apparatus as claimed in claim 4 including:
insulating means disposed between said one switch contact and said
hopper sidewall means to prevent electrical contact therebetween,
said switch being closed through electrically conductive material
within said hopper engaging both said sidewall means and said one
switch contact.
6. Apparatus as claimed in claim 4 including:
insulating means disposed between at least a portion of said one
contact and said sidewall means for normally preventing electrical
contact therebetween;
said one contact having a portion movable in response to engagement
by material in said hopper for engaging said sidewall means to close
said switch means.
7. Apparatus as claimed in claim 6 wherein:
said one contact has a skirt portion depending below said insulating
means and normally spaced from said sidewall means, said skirt means
being segmented to permit deflection thereof into electrical contact
with said sidewall means in response to engagement by said material
in said hopper.
8. Apparatus as claimed in claim 1 wherein:
said hopper sidewall means is conductive;
and including:
electrical insulating means separating said hopper sidewall means
into two portions electrically insulated from each other;
each of said portions comprising one of said contacts;
whereby said switch is closed in response to electrically conductive
material in said hopper spanning said insulating means and engaging
both of said sidewall portions.
Description BACKGROUND OF THE INVENTION
The present invention relates to swarf crushers and similar structures
in which material to be crushed is supplied to the crusher through
a supply hopper supported thereon. Typically, such crushers operate
for a time interval sufficient to process a load of material in
the crusher and the cooperating hopper.
In order to control the operating cycle of the crusher, it has
been the practice to utilize a small spot sensor in the hopper for
determining when the hopper is filled to a desired level. The sensors
which have been utilized have not been satisfactory and all too
often have not provided the desired control of the crusher operation.
They have not accurately sensed the level of material in the hopper
even though the hopper was filled to the desired level.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a crusher
for swarf and similar material having a chamber in which the material
is crushed and including a material supply and storage hopper communicating
with and supported on the crushing chamber. The hopper incorporates
a suitable material sensing mechanism which is constructed to respond
to material in the hopper reaching a selected level to positively
ensure response to the material in the hopper and enable the control
circuit for the crusher.
More specifically, in accordance with the present invention, a
sensing switch forming a part of the control circuit for the crusher
has a portion disposed within the hopper and extending a substantial
distance about the periphery thereof to ensure responsiveness to
materials in the hopper reaching the selected level. Such a sensor
has sufficient surface area disposed within the hopper to ensure
the sensing mechanism responding to material.
Numerous other advantages and features of the present invention
will become readily apparent from the following detailed description
of the invention and of one embodiment thereof, from the claims
and from the accompanying drawing in which each and every detail
shown is fully and completely disclosed as a part of this specification
in which like numerals refer to like parts.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatic view of a crushing apparatus incorporating
the present invention;
FIG. 2 is an enlarged sectional view of a hopper taken along the
lines 2--2 of FIG. 1;
FIG. 3 is a sectional view similar to FIG. 2 showing an alternative
embodiment;
FIG. 4 is a partial sectional view similar to FIG. 2 showing a
modification of the embodiment of FIG. 2;
FIG. 5 is a partial sectional view similar to FIG. 3 showing a
modification of the alternative embodiment of FIG. 3;
FIG. 6 is a partial sectional view showing yet another alternative
embodiment; and
FIG. 7 is a diagram of a circuit for controlling operation of the
crusher.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
While this invention is susceptible of embodiment in many different
forms, there is shown in the drawings and will herein be described
in detail a preferred embodiment of the invention and modifications
thereof, with the understanding that the present disclosure is to
be considered as an exemplification of the principles of the invention
and is not intended to limit the invention to the embodiments illustrated.
The scope of the invention will be pointed out in the appended claims.
FIG. 1 shows one embodiment of a swarf crusher 10 and a discharge
conveyor 12. This type of crusher is manufactured, for example,
by Morgardshammar AB, of Sweden under the trademark ARBOGA. Such
crushers are primarily intended to crush swarf, i.e., turnings of
carbon steel, stainless steel, other alloyed steels, aluminum alloys,
sponge iron, titanium and uranium although it may be used to crush
other types of materials such as, e.g., plastics and glass.
The crusher 10 includes a generally conical crushing chamber 14
defined by a generally downwardly and inwardly tapered sidewall
16 and is open at the top for receiving material to be crushed.
The open bottom of the crushing chamber 16 is supported on a suitable
stand or base portion 18 through which extends a drive shaft 20
to which is affixed a crusher head 22. The crusher head 22 is rotated
on the drive shaft and cooperates with stationary crusher members
or cutters 24 affixed to the inner surface of the crushing chamber
sidewall 16.
The open bottom of the crushing chamber 14 communicates with a
discharge chute 26 affixed to and/or incorporated as a part of the
base portion 18 for providing a discharge path for crushed material.
The drive shaft 20 is driven by an electric motor 28 connected thereto
through a suitable drive train 29.
Material to be crushed is introduced to the crushing chamber 14
through a material receiving and storage hopper 30 disposed above
and supported on the crushing chamber 14. As seen in FIG. 1 the
hopper 30 is formed by a sidewall 32 including an upper cylindrical
sidewall portion 32a and a lower conical sidewall portion 32b which
merges with the conical sidewall 16 of the crushing chamber 14.
The hopper 30 which communicates through its open bottom with the
crushing chamber 14 has an open top 34 for receiving material to
be crushed.
In the embodiment shown in FIG. 1 the base of the crusher is supported
on a conveyor housing 36 disposed at one end of the discharge conveyor
12 driven by conveyor motor 38 (FIG. 7). A pair of spaced material
retaining walls 40 (only one being shown) are disposed on either
side of the conveyor 12 adjacent to the discharge chute 26 for retaining
material deposited on the discharge conveyor 12.
A proximity switch 42 may be mounted in one of the conveyor retaining
walls 40 for sensing an accumulation of crushed material on the
conveyor 12 adjacent to the end of the discharge chute 26 and forms
a part of the crusher control circuit (described in more detail
below). The proximity or high level sensing switch 42 is operative
to temporarily stop the crusher 10 thereby permitting the conveyor
12 to transport material away from the discharge chute 26 and prevent
excessive accumulation of crushed material in the area adjacent
to the high level switch 42 which might result in the material backing
up into the crusher and inhibiting proper operation thereof or overflow
of the material from the conveyor.
Typically, and in order to maximize the effeciency of operation
of the crusher, the crusher is operated for a selected time interval
which is sufficient to process a load of material disposed in the
hopper 30 and crushing chamber 14. A level sensing mechanism or
switch 44 is provided in the hopper 30 the switch 44 enabling the
control circuit for the crusher when material in the hopper 30 reaches
a selected level. The level switch 44 or the portion thereof disposed
within the hopper 30 is adapted to be engaged by material in the
hopper 30 when the hopper is filled to the selected level, thereby
enabling the control circuit and permitting operation of the crusher
10. In existing structures, a spot-type sensor has been used which
has proven to be relatively unreliable because material in the hopper
often does not engage the sensor even though the hopper is full.
Referring to FIG. 2 there is shown an improved high level sensing
mechanism 44 mounted on sidewall 32 of the hopper 30 which typically
is constructed of an electrically conductive metal such as sheet
steel. The sensing mechanism 44 includes a first switch contact
or electrode in the form of a strip of electrically conductive material
46 such as brass, which extends peripherally about the entire inner
surface of the hopper sidewall 32. The vertical dimension of the
switch contact 46 its width or height, together with its substantial
lateral dimension or length, provides a surface area sufficient
to substantially preclude non-engagement therewith by material filling
the hopper 30.
As shown in FIG. 2 the contact 46 is spaced from the electrically
conductive hopper sidewall 32 by an insulating strip 48 to which
it is affixed by suitable means such as bolts or screws 49. In the
embodiment shown in FIG. 2 the insulating strip 48 extends above
and below the contact to ensure electrical separation of the contact
46 and the hopper sidewall 32. The insulator is, in turn, attached
to the sidewall such as, for example, by studs 50.
The electrode or contact 46 and the sidewall 32 of the hopper 30
act together as the normally open contacts of the level sensing
switch 44. The hopper wall 32 is connected to the control circuit
by a wire lead 52 suitably connected thereto such as by a conductive
bolt 54 passing through one end of the wire and affixed to the sidewall
32. The electrode 46 is connected to the control circuit by another
wire lead 56 affixed to one end of a conductive bolt 58 having conductive
engagement with the electrode 46 and having the shaft passing through
the sidewall 32 and insulated therefrom by suitable insulating gaskets
60 and spacers 62. As seen in FIG. 2 this portion of the switch
44 may be suitably encased in a protective housing 64.
In the embodiment shown in FIG. 2 the contacts of the level switch
44 the conductive brass strap electrode 46 on the one hand and
the conductive hopper sidewall 32 on the other, are closed when
the hopper is filled up to a level where the material in the hopper
engages the brass electrode 46. Since, as indicated above, the crusher
is primarily intended for metallic turnings, the engagement of the
electrode 46 by the material within the hopper 30 completes an electrical
circuit from the contact electrode 46 through the electrically
conductive swarf to the hopper sidewall 32 to effectively close
the level sensing switch 44 and enable the control circuit, as described
in more detail below.
Alternatively, it may be desirable to construct the level sensor
to provide an alternative for closing the switch which would be
particularly useful when the material to be crushed is not electrically
conductive or has low electrical conductivity. In this embodiment,
shown in FIG. 3 the electrode 66 has a skirt portion 68 extending
below the insulator 48. If the electrode 66 extends completely around
the periphery of the inner surface of the sidewall 32 the skirt
may be slotted at 69 into a plurality of skirt sections 68a to facilitate
deflection of the skirt 68 directly against the conductive sidewall
32 when engaged by material in the hopper 30.
The embodiments of FIGS. 1 and 2 may also be adapted for use with
non-conductive sidewalls by interposing between the insulator 48
and the inner surface of the sidewall 32 an additional conductive
electrode 70. The additional electrode is configured to make contact
with either the swarf alone as shown in FIG. 4 or with either the
swarf or the deflected skirt portion 68 as shown in FIG. 5.
Finally, as seen in FIG. 6 the conductive sidewall 32 could be
divided into two segments 32", 32'" separated by an insulating
member 72. In this embodiment, the lower portion 32" is one
contact and the upper portion 32'" is the other.
The control circuit 100 enabled by the level sensor 44 is shown
in FIG. 7.
The crusher motor 28 and the discharge conveyor motor 38 are connected
through a main power line 102 to a suitable source (not shown) through
a main power disconnect switch 104. The source is conveniently a
three phase 440 volt source. The main power line 102 is connected
to crusher motor 28 and the discharge conveyor motor 38 through
appropriate contactors.
The main power line 102 is also connected to the primary of a transformer
106. The secondary of the transformer 106 is connected to a pair
of main buss lines 108 110 for supplying power to the control circuit
100. A manually operated master stop switch 112 is connected in
one of the main buss lines 110 for manually disconnecting the control
circuit 110 from the power line 102.
The control circuit 100 permits two modes of operation of the crusher,
a run mode and a maintenance mode, determined by the run/maintenace
switch 114 which is a two position switch having a first pair of
contacts 114-1 (line H), a second pair of contacts 114-2 (line J)
and a third pair of contacts 114-3 (line Q). In FIG. 7 the contacts
of the run/maintenance switch 114 are shown open which is in the
run position. In order to avoid an undesired accumulation of crushed
material at the conveyor, when one is used, the crusher can not
be started when the switch 114 is in the position shown, unless
the discharge conveyor 12 is running. The control circuit 100 also
precludes operation of the crusher 10 unless there is a sufficient
amount of material in the hopper 30 to engage the level switch 44
and thereby enable the control circuit 100.
In addition, the control circuit 100 is effective to preclude operation
of the crusher 10 or at least temporarily interrupt operation of
the crusher, when there is an excessive accumulation of crushed
material on the discharge conveyor 12 adjacent the discharge chute
26 all of which will be explained below.
When the switch 114 is in the maintenance position, i.e., the contacts
114-1 114-2 and 114-3 are closed, permitting the crusher 10 to
be started independently of the conveyor 12 without material in
the hopper 30 and independently of any accumulation of material
on the discharge conveyor 12.
In order to initiate operation of the crusher when switch 114 is
in the position shown in FIG. 7 it is first necessary to start
the conveyor 12 by closing the conveyor start switch 116 (line B).
This energizes the conveyor motor starting coil 118 through the
normally closed conveyor stop switch 120 and the normally closed
contact 122-1 of the conveyor overload switch 122 (all in line B).
The conveyor overload relay coil 112 is in the motor circuit.
When energized, the conveyor motor start coil 118 closes the contacts
118a of the contactor conveyor motor circuit, the normally open
holding contacts 118-1 (line C) to maintain the starter coil 118
energized after release of the start switch 116 the normally open
contacts 118-2 (line H) to enable crusher start switch 124 and
normally open contacts 118-3 (line I) which operate as part of a
bypass circuit to keep the crusher operating after it is started.
To start the crusher, the crusher forward start switch 124 (line
H) is closed to complete a circuit through the now closed contacts
118-2 the normally closed contacts 125-1 of the crusher overload
relay 125 and the normally closed crusher stop switch 126 to energize
start relay coil 128 and the pilot light 129 connected across the
start relay coil 128. The overload relay 125 is in the crusher motor
circuit. When the start relay coil 128 (line H) is energized, it
closes a first set of normally open contacts 128-1 (line I) which
are connected in series with the contacts 118-3 closed when the
conveyor motor coil 118 was energized, to bypass the crusher forward
start switch 124 and maintain the start relay coil 128 energized
after release of the start switch 124.
The start switch 124 and bypass circuit including contacts 118-3
and 128-1 are also connected to the timing relay coil 130 (line
I) through the normally open contacts 132-1 of the level sensing
relay 132 (lines N and O). Contacts 132-1 are closed when the relay
132 is energized in response to closure of the level sensing switch
44 in the hopper 30.
The energized start relay 128 also closes a set of normally open
contacts 128-2 (line L) to enable the balance of the control circuit
100. Closure of the start relay contacts 128-2 completes a circuit
(line 0) to the primary coil 132a of the level sensing induction
relay 132 through the normally closed contacts 134-1 (line O) and
134-2 (line M) of the duration timer 134. The crusher 10 will begin
to operate if the level sensing switch 44 connected to the secondary
132b of the level sensing relay 132 is closed, thereby closing the
relay contacts 132-1 (line I) to energize the timing relay 130.
As explained below, the crusher 10 will continue to operate until
the duration timer 134 times out, until the crusher 30 becomes jammed,
until the motor 28 becomes overloaded, or until excess material
accumulates on the discharge conveyor 12.
When the timing relay 130 (line I) is energized through the closed
level relay contacts 132-1 the normally open timing relay contacts
130-1 (line L) will close approximately 5 seconds after the timing
relay coil 132 is energized. This time delay prevents material being
introduced into the hopper 30 and momentarily engaging the level
switch 44 from energizing the crusher. In other words, the material
must close switch 44 for a period of approximately 5 seconds, a
good indication that the hopper is filled to the selected level,
before the crusher will start.
When the timing relay contacts 130-1 (line L) close, the duration
timer 134 is energized. The duration timer 134 includes a clutch
134a, which operates instantaneous timer contacts 134-2 (line M)
and instantaneous contacts 134-3 (line O), and a timer motor 134b
which operates delayed contacts 134-1 (line O). In addition, a timer
pilot light 134c is connected across the motor 134b to show when
the timer 134 is in operation.
Thus, upon energizing the duration timer 134 the instantaneous
contacts 134-2 (line M) shift from the normally closed to the normally
open position to de-energize the primary 132a of the running level
relay 132 and to maintain the duration timer 134 energized. When
the primary 132a of the running level induction relay 132 is de-energized,
the induction relay contacts 132-1 (line I) open to de-energize
the timing relay coil 130 thereby opening the timing relay contacts
130-1 (line L).
The second set of instantaneous duration timer contacts 134-3 (line
O) also shift to the normally open position to energize through
the normally closed conveyor high level relay contacts 136-1 (line
P) a second timing relay coil 138 (line Q) and the crusher forward
motor coil 140 (line R) through the normally closed second timing
relay contacts 138-1 (line Q), the normally closed contacts of a
first crusher run sense switch 142 the normally closed contacts
144-1 of manual reverse jog switch 144 and the normally closed contacts
146-1 of the reverse motor coil 146.
When the forward motor coil 140 is energized, it closes the contacts
140a of the crusher motor connector to initiate forward rotation
of the crusher motor 28 and closes contacts 140-1 (line L) to start
the duration timer motor 134b, and also opens the normally closed
contacts 140-2 (line Z) to preclude energizing the reverse motor
coil 146.
When the crusher begins to operate, a second crusher run sense
switch 148 (line R) moves from the normally closed to the normally
open position to bypass the normally closed contacts 138-1 of the
second timing relay 138 which contacts open approximately 4 seconds
after the second timing relay 138 is energized. This delay permits
the second run sense switch 148 to shift to the normally open position.
The energized second timing relay 138 also closes normally open
contacts 138-2 (line T) after an approximate 4 second delay to enable
the jam control and timing circuit, to be described in more detail
below.
In normal operation, the forward motor coil 140 (line R) will remain
energized and the crusher will continue to run until the duration
timer 134 times out. At the end of the timing interval, which is
adjustable, the duration timer 134 times out opening the delayed
contacts 134-1 (line O). When the delayed duration timing contacts
134-1 open, the duration timer clutch 134a is de-energized. As a
result, the instantaneous duration timer contacts 134-2 and 134-3
return to their normally closed position to de-energize the forward
motor coil 140 and to enable the primary coil 132a of the running
level relay 132.
When the clutch 134a is de-energized, the delayed duration timer
contacts 134-1 are reset to complete the circuit through the primary
coil 132a of the running level relay 132. When the crusher stops,
the second run sense switch 148 returns to its normally closed position,
but the jam timer is not energized since the second timing relay
138 has also been de-energized when timer contacts 134-3 (line O)
return to their normally closed position.
Since the start relay coil 128 (line H) and the conveyor motor
coil 118 (line B) remain energized, the control circuit 100 will
recycle when the hopper is filled to the level sufficient to close
the running level switch 44 in the secondary 132b of the running
level relay 132 thereby again closing the relay contacts 132-1
(line I) to repeat the cycle described above.
If the crusher 10 becomes jammed, the drive shaft 20 will stop
even though the forward motor coil 140 is energized. When this occurs,
the second run sense switch 148 (line R) returns to its normally
closed position. This results when timing relay contacts 138-1 (line
Q) are opened in de-energizing the forward motor coil 140 thereby
opening the contacts 140-1 (line L) temporarily terminating operation
of the duration timer motor 134b to interrupt the timing cycle,
and closing the contacts 140-1 (line Z) to the reverse motor coil
146.
Since the second timing relay coil 138 (line Q) remains energized,
thereby closing contacts 138-2 (line T), the normally closed contacts
of the run sense switch 148 complete a circuit through the motor
150a (line T) of a jam cycle timer 150. The jam cycle timer motor
150a when energized controls the operation of three cam operated
switches 150-1 (line V), 150-2 (line Z), and 150-3 (line X). The
first switch 150-1 closes approximately 1.8 seconds after the cycle
150a is energized to maintain the motor 150a energized, and to complete
a circuit to jam duration timer 154. The switch 150-1 remains closed
for approximately 9 seconds, the jam timing cycle.
The second cycle timing switch 150-2 closes at about the same time
as the first switch 150-1 to energize the reverse motor coil 146
and pilot light 155 connected across the motor coil 146. When the
reverse motor coil 146 is energized, it closes contacts 146a in
the crusher motor circuit and opens normally closed contacts 146-1
connected in series with the forward motor coil 140 to preclude
energization thereof. The second cycle timing switch 150-2 remains
closed for approximately 4 seconds so that the crusher will run
in reverse for that period of time.
Approximately 5 seconds after the cycle timer 150 is energized,
the second switch 150-2 opens and the third cycle timing switch
150-3 is closed to re-energize the forward motor coil 140. The second
run sense switch shifts from the normally closed to the normally
open position to hold the forward motor starter coil 140 energized.
If, as a result of this action, the jam is cleared, the normally
open contacts of the second run sense switch remain closed and the
crusher will continue to run forward until the duration timer times
out as explained above.
The jam cycle timer 150 times out after approximately 9 seconds
thereby opening the first and third cycles switches 150-1 and 150-3
respectively, and de-energizing the jam timer 150 if the crusher
is unjammed and is running in the forward direction. If, however,
the crusher is still jammed when the cycle timer runs out, the normally
closed contacts of the second run sense switch 148 remain closed,
keeping the cycle timer 150 and jam timer 154 energized and repeating
the jam cycle.
If after a period of time, for example, approximately three cycles
of the cycle timer 150 the crusher is not unjammed, the jam timer
154 will time out opening the delayed contacts 154-1 (line T) and
154-2 (line V) to energize the jam indicator light 156 and maintain
the jam timer clutch energized.
Since the forward motor coil 140 is de-energized under these circumstances,
the forward motor coil contacts 140-2 (line L) are open to interrupt
the duration timer 134. In order to restart the crusher after the
jam is cleared, a manual reset switch 156 (line G) may be closed,
or alternatively the entire control circuit may be reset by operating
the crusher stop button 126 (line H). If reset, the hopper must
be refilled to a sufficient level to close the level switch 44 and
to initiate a complete operating cycle.
If either of the motors 28 or 38 becomes overheated, the corresponding
thermal overload relay 122 125 respectively operates overload
contacts 122-1 or 125-1. In either case, the entire control circuit
is de-energized and reset.
Finally, if material accumulates in the crusher discharge conveyor
to a high enough level to activate the high level detection switch
42 (line D), the switch is closed to energize the high level relay
136 and high level indicator light 158. The energized high level
relay opens the normally closed high level relay contacts 136-1
(line P) to de-energize the second timing relay coil 138 and the
forward motor coil 140. When the level of material in the discharge
conveyor drops low enough to open the high level proximity switch
42 the high level relay is de-energized. The relay contacts 136-1
close approximately 5 seconds thereafter, thereby allowing the accumulation
of material in the conveyor to drop even lower, to re-energize the
second timing relay 138 the forward motor coil 140 and the duration
timer 134.
Thus there has been disclosed, a crusher for swarf and similar
material in which the control circuit therefor is enabled in response
to material in the hopper reaching a selected level, and in which
the switch means for sensing material in the hopper is constructed
to ensure that the material is sensed in order to properly enable
the control circuit under the selected conditions.
From the foregoing, it will be observed that numerous variations
and modifications may be effected without departing from the true
spirit and scope of the novel concept of the invention. It is, of
course, intended to cover by the appended claims all such modifications
as fall within the scope of the claims. |