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Патент USA US2405985

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Aug. 2o, 1946.
Filed Sept. 2, 1945
4v Sheets-Sheet E."
Haroîd .5., Sim' líZandJí:
B V..
AUS- 20, 1946»
H.~A. s'rRlcKLAND, JR
Filed Sept. 2, 1943
4 Sheets-Sheet 3
Harold ß. «S'Zrz'cìîla‘mdJìr
Aug- 20, 1946»
Fiied sept. 2, 1943>
4 Sheets-Sheet 4
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Patented Aug. 20, 1946
Harold A. Strickland, Jr., Detroit, Mich., assign
or, by mesne assignments, to The Budd Com
pany, Philadelphia, Pa., a corporation of Penn
Application September 2, 1943, Serial No. 500,903
16 Claims. (Cl. 219-13)
This invention relates to induction heating ap
paratus. More particularly the invention relates
to heating apparatus provided with mechanism
adapted for holding workpieces of varying lengths
including an extreme length beyond that of the
furnace casing.
In induction heating apparatus such for exam
closure means for the feed opening, but capable
of independent movement of said closure means;
and to provide simplified construction for the
operation of the induction heating apparatus.
Other objects will appear on examination of the
following description of the invention taken with
the accompanying drawings, in which:
Fig. 1 is a side elevation of the upper portion
ple as described in my co-pending application,
of the heating apparatus showing the furnace
Serial No. 384,503, filed March 21, 1941, use is
made of an induction heating coil within which 10 casing and associated control apparatus;
Fig. 2 is a front elevational view showing the
a workpiece is inserted, the feed opening of the
heating coil being normally closed in the heat
ing cycle by a pivoted hood which functions to
initiate the heating operation and also to pre
feed opening closure mechanism, partly in sec
Fig. 3 is a vertical section taken through the
vent access for removal of the workpiece while 15 control box showing the means for initiating the
heating cycle;
the heating current is effective. This is of im
. Fig. 4 is a vertical section taken along the lines
portance in order to protect the workmen from
.4-4 of Fig. 3;
possible electrical breakdown and shock and also
Fig. 5 is a horizontal section taken just below
to prevent removal and re-insertion of the work
piece during the continuance of the heating cycle. 20 the top casing wall of Figs. 3 and 4 and illus
\trating the control mechanism;
A disadvantage of this construction resides in the
Fig. 6 is a detail showing the relationship of
fact that the furnace cannot operate with a work
ì«workpiece and holding means at the front open
?¿ing or mouth of the furnace;
tends outwardly beyond the hood thus preventing
closing of the hood and the initiation of the heat 25 Fig. '7 is a section along the lines `I--1 of Fig. 6,
piece of such length that a portion thereof ex
ing action.
One of the primary objects of the present in
Fig. 8 is a wiring diagram of the electric cir
vention is to provide a holding or electrical
Referring to Fig. 1, I have shown in outline
grounding device and closure means for a work
electrical induction heating apparatus hav
piece in an induction heating coil furnace which
ing particular adaption to the heating of bars
is effective to clamp a workpiece of extreme length
or the like. The construction of the apparatus is
without interfering with the normal heating
in general similar to that shown in my co-pend
ing application above referred to and includes
workpiece in the apparatus which also provides a 35 three sections, the numeral I0 being applied to
the furnace section proper, the numeral Il to
ground in case the workpiece should be removed
`the section including the control mechanism and
during the heating cycle. Still another object
‘the numeral I2 to the section containing con
is to provide a clamping means for workpieces,
_densers and bus bar connections.
which is automatically adjustable to workpieces
The furnace section I0 is provided with a cas
of different diameter. Still another object is to
ing I3 and a front end plate UI within which is
provide a clamping means for a workpiece which
shown in dash outline the base plate I5 support
in the case of a short workpiece moves to close
ing C-brackets I6 the latter in turn supporting
the feed opening to prevent removal of or con
the induction heating coil unit I1. The feed
tact with the piece while heating is in progress.
An additional object is to provide a clamping « opening or mouth I8 formed in a. plate 6 at
tached to the end plate I4 is in extension of the
or closure means for a heating coil which func
heating chamber I9 of the heating coil and with
tions in time sequence in relation to the means
in this chamber and extending outwardly be
for initiating the heating cycle. Additional ob
yond the feed opening is a workpiece 20. Feed
jects are to provide a holding means for a work
piece in an induction furnace which functions 50 ppening guide ring 2| functions to assist in the
support of the workpiece 20 as well asA to aid in
normally in conjunction with the means for ini
guiding the workpiece into the end of the coil,
tiating the heating cycle but which may func
Aas described in my co-pending application Se
tion independently thereof without disturbance
rial No. 506,016, filed October 13, 1943, now Pat
of the cycle initiating means; to provide means
for closing a relay circuit simultaneously with the 55 ent No. 2,400,660, dated May 21, 1946.
function of the apparatus. Another important
object is to provide means for clamping a long
Means for grounding the workpiece or alter
nately for preventing removal thereof where the
workpiece is of such a length as to be included
within the casing, is illustrated particularly in
Figure 2 of the drawings. In this figure there is
shown in horizontal alignment with thecenter
of the workpiece >2i) and on either side of the
same, clamping mechanisms 22 and‘23, each con
sisting of a cylinder 24 secured by bolts 25 to
the outer face of the end plate It. These cyl
inders are each provided with pistons 26 having
projecting piston rods 2ï, the pistons normally
being urged outwardly in relation t0 the Work-
Adapted for axial movement also within the
casing ¿i3 is the valve rod 56 which is axially
hollowed at the end adjacent the valve member
5|) to form a channel 51 extending from the free
end of the rod 56 to a point 58 where a lateral
duct opens from the rod into a transverse duct
59 formed in a stationary member 50 within
which the rod 5t is movable' and communicat
ing with the exhaust 44. A chamber 6| sepa
rates the rubber plate of member '50 and the end
of the valve rod 56, said chamber communicat
ing with the outlet port 45. Within this chamber
also is a coil spring S2 surrounding the end of
piece by coil springs 28. The inner ends of the
the valve red for retaining the packing in place
piston rods terminate in lateral yokes 29 having 15 as shown in Figurey 5,. In this position fluid under
pivot rods 3Q on which are mounted rollers 3|
forming the clamping or closure elements for the
workpiece. Rollers are required because of axial
expansion of the workpiece while heating. ' In op- ’
~ressure in the clamping mechanisms 22 and 23
will havefree exitythrough the conduits 32 and
chamber 6| and duct 57 to the exhaust port
d4, thus relieving the pressure in the cylinders 24
eration, when pressure is led into the cylinder 20 of the holdingunits and permitting movement
chamber, as by pipe lines 32, the pistons are
ofthe holding member away from the workpiece.
movedVA inwardly, carrying the holding elements
In Figures 4 and 5 the adaptation of the valve
3| into engagement with the workpiece 20 if ex
means is shown for use in connection with the
tending through the feed opening of the furnace,
operation of electric switches |24 and |25. These
thepressure of the pistons being such as to main 25 switches are included in the casings 63 and 61|v
tain they rollers- iixedly in position against the
and utilize spring operating plates S5 and 66.
workpiece, effectively> grounding the same
These spring plates, as shown, are fastened by
through the all-metal structure of the machine
screws to the switch casings and hence are freely
frame. In the case of a workpiece included en
movable to operate switch plungers intermediate
tirely within the furnace casing, the contact roll
. the spring plat-es and the casings 63 or 54. The
ers «move-into close-position with each other and
free ends of these spring plates underlie the an
present an effective barrier against removal or
nular flange 5l formed on the inner end of the
Contact with a workpiece. Cross guide plates 33
hollow push button ft2, so that axial movement of »
are welded to the inner edges of the yokes 29 to
the push button causes movement of the spring
prevent-'rotation of the roller suspensions on the 35 members and consequent actuation of the
otherwise rotatable piston rods, as well as for sup
switches within the casings 63 and 611. In order
plementation of the rollers in coacting as a bar
to secure this vswitch actuation to some degree
rier for the feed opening.
Control apparatus for initiating the movement
independently of the actuation of the three-way
valve, the push button is'slidingly mounted on
of »the holding or closure means 3| as hereinabove 4.0.; the end of an extension of the valve casing 43,
described is shown in detail in aFigures 3 through
so as to have a limited sliding movement relative
6, and «is referred to generally by the numeral 35.
tothe valve `casing before engaging the valve rod
This unit is enclosed in a casing 36 attached by
5Bwhen-mo'ved .toward the rod. To this end the
adjustable screw bolts 5 to the end plate I4 above
tubular casingtß is screw threaded within the
andY toone side of the feed opening of the work
„ push button head, this casing extending to and
piece and heating coil and directly above the
having slidable engagement with the outer end
pressure cylinder 23 as shown in Fig. 2. The cas
Geef. a coupling 'le screw threaded to the Valve
ing~36 is box-shaped and is provided on its outer
casing 43. The inner end of this tube 68 is closed
face 3l lwith enlarged spaced openings 38 and 39,
byan inwardly extending annular ñange except
one above the other. Within the casing 36 and 50k fora central aperture within which the stem of
ñxed to the end plate I4 is a base plate el) to
a vheaded member li placed withinA the tube 68
which at the upper end thereof is ñxed a three
is movable. A coil spring l2 is positioned within
the casing GQ which normally urges the headed
the base-plate 4i! through the opening 38 in the
member 'Ii into the extreme inward limit of move
control casing and terminating-in a push button
ment with sufñcient initial pressure so that the
52 whereby the valve is operated.
spring is compressed further ‘only after the valve
>The three-way valve structure is shown more
rod ,56 is pressed against its rubber seat 55.
clearly in Fig. 5, the valve comprising a casing
Thel protruded stem of the member 1| is
¿i3 having an exhaust port 44, and inlet port 45,
normally adjacent but out of contact with
and an outlet port 55. The inlet port is coupled 60 the outer end of the valve rodtt. The guiding
to an-inlet pressure conduit ¿l1 and the outlet
collar ‘F3 on the Valve rod 56 'holds the end of the
port, through a conduit 98, to the pipe line 32
valve rod in position and also provides a seat for
associated with the pressure units 22 and 23.
the inner 'and outer coil springs 'M and 'l5 where
Within the casing 43 of the valve adjacent the
bythe head and the attached valve stem are.`
inlet port 45 is a chamber 49 in which a freely 65 normally urged to outward position and packing
floating valve member 5e is adapted to have axial
is pressed around'the valve rod 55.
movement. 'This valve member is formed as a
The periphery of the annular ñange 6l is in
way valve unit 4| extending horizontally from
circular plate 5| with axially extending edges 52
clined toward the axis of the valve in a direction
forming depressions on either side of the plate 5|,
awayfrom the cap of the button to form a cam- ,
the end of the plate adjacent the base 40 form 70 ming surface l5. Adapted to cooperatively en
ing a'recess for a coil spring 53 which normally
gage' this camming surface is a similar surface
urges the valve member 50 axially against the
formed on the member Tl mounted on the pivot
other side '54 of chamber 49. The other recess
pin` T8, supported beneath the extension casing
ofthe valve member 50 holds a soft rubber plate
'lil :of the valve. In operative position of the
75 mechanism the camming surface of thev member
11 engages the camming surface of the ilange 61
à and is held in this position by means of a coil
pivot spring 19. It now appears that when pres
sure is applied to the push button 42 the initial
ders 24, so that this switch and the holding mech
anisms are directly related and act simultane
Similarly on release of the pressure in the
holding cylinders the pressure switch is operated
action will be to forcel the pivotal member 11'l to open and break the circuit.
Terminal bar |00 mounted on angle plates |04
downwardly until the cam surfaces override each
is also positioned within the casing and attached
other, whereupon the spring 19 will force up the
through the angle plates to the base plate 40.
pivotal member, so that its end engages the edge
The wiring diagram of the heating apparatus
_of the flange 61 thereby holding the push button
in a predetermined fixed position inwardly of its 10 is shown in Fig. 8 the power source supplying
alternating current being indicated at ||0, and
normal inoperative position. The push button is
the main circuit lines at ||| and ||2. The cir
maintained in this inward position until thepiv
otal member is forced outwardly to such an ex
cuits may be roughly classified in live sections
in this frame and secured to the base plate 40 is
an electro-magnet 3 having an armature 85 mov
able therein in an approximately vertical direc
B is based on a pilot contactor relay |2| which
on energization is adapted to close the contacts
of switches |22 and |23. In addition to the basic
tion, the outer end of the armature terminating
in the double arch-shaped member 81 having
apertures adapted to receive the cross pin 84.
Spacing tubes 88 are placed on said cross pin in
termediate the member 81 and- the depending side`
plates S3 to hold the frame in ñxed relationship 35
elements mentioned, the starting circuit includes
the starter switches |24 and |25, pilot lamp |26
and main contactor relay switch |21, the circuit
passing from main line ||2 through tap line |28,
pilot lamp |26 and relay |2| in parallel, main
relay switch |21, pilot contactor relay switch
|23 and starter switch |24 in parallel, and starter
designated as "Supply,” “Startingf’ “Load safe
tent as to permit the ilange of the push'button
to, escape from the detent and move to its normal 15 ty,” “Timer” and “High frequency” and iden
tir-led as in the -drawings as YA, B, C, D and E
outer limit. The means for releasing the push
respectively. The supply section A includes fuses
button and its movement‘of the pivotalmember
| |3, overload disconnection heating elements | I4,
11 comprises the lever arm‘80 pivotally mounted
, and lmain switches |I5. Included also are the
on the pivot 18 and extending between the’mem
'ber 11 and the extension valve casing 10. On 20 main power line 60 cycle pilot lamp H6, water
’ pressure switches ||1, water pressure pilot lamp
the opposite side of the pivot from the lever 8|),
l |8, Water heater H9, and water thermostat |20.
the arm 8|, integral with the lever, extends and
~ Main lines ||| and ||2 extend from the supply
Yterminates in a pivot pin 82 to which side plates
circuit A into the Starting and load protective
83 are attached extending freely downwardly to
circuits B and C, these two sections being mutu
engage the cross pin 84 at the base thereof, thus
ally dependent for operation. Starting circuit
forming a square-shaped pendent frame. With
to said member.
With this construction, on en
ergization of the electro-magnet, the attraction
switch |25 to the load safety section C.
of the member 81 results in an upward movement
from starter and pilot relay switches |23 and
|24 a branch line leads through pilot relay |22
of the same. The frame is lifted thereby operat
ing the arm 8| and causing the lever 80 to press 40 to a sequence or distributor switch |48, which
selects the particular furnace of a bank of fur
the pivot member downwardly thereby releasing
naces for energization, and thence to the timer
the push button from its inwardly placed posi
circuit section D.
` , An alternative manual means for operating the
The basic elements of the load-safety section
lever 80 is also provided in a second arm 90 fixed
C are the anti-reset relay |29 and load switch
to the arm 8| and extending generally downward
ly therefrom and toward the front side 31 of the
contact elements 8a, 8b and |0|a, |0|b. Anti
reset relay | 29 is adapted on energization to close
' control casing 36.
The end of this arm termi
anti-reset relay switches |3| and |32.
In addition to the Aenumerated basic elements,
nates in a Contact plate 0| adjacent the aperture
39 in the lower side of the front control plate 3T. 50 there is included in the C section the anti-reset
pilot lamp |36, and water temperature and flow
Extending rearwardly from the sides of the open
switches |40 and |4|. The circuit leads from
ing 39 is guide casing 92 having an inner wall
mainline | || through water temperature and
formed with a central aperture. Movable with
in this aperture is a plunger 93 having a linger
ñow switches |40 and | 4|, load switch contact
plate 94 and an end stop 85 attached tothe 55 elements 8a and |0|a in parallel, through anti
reset relay switch |32, junction point |44, to hood
plunger external to the inward aperture thereof.
switch |25 of the B section. Also from main
A spring 36 is coiled around the plunger within
line ||2 the circuit leads through the anti-reset
the guide casing 92 between the ringer plate 94
.relay coil |29 and pilot lamp |36 in parallel to
and the inner edge of the plunger receiving aper
ture. The action of this spring is to normally 60 a common junction |42; thence by anti-reset re
lay switch |3| to a common junction point |43.
maintain the ñnger plate at the outer limit of its
From point |43 the circuit leads through switch
Amovement but to permit yieldable inward move
contact elements |0|b and 8b to point |42.
ment of the finger plate whereby the end or the
Switch contact elements |û|b and 8b are nor
plunger is moved against the contact plate 3|
of the lever 90 and thus moves the lever arm 80 65 mally closed, and switch contact elements 8_a
and |0|a normally open.
downwardly to cause release of the push button.
The timer current section D is formed princi
On reference to Fig. 5 it will be observed that
pally of two timers of any appropriate commer
`the connections from the outlet 46 through the
cial make together with related elements. The
pipe. line 48 terminates in a coupling 91, one end
of which is connected to the pipe 98 leading into 70 function of the timer is to eiîect a timer limit,
subject to adjustment, on the amount of heat
the clamping pipe line 32 (Fig, 2) and the other
received by the workpiece and two timers vare
end connected into the pipe line 99 having con
used to insure completion of a heating cycle in
nection to a pressure operated switch |84 shown
case one timer should fail to perform properly.
in Fig. 4. This switch is adapted for actuation
Whenever pressure is applied to the holding cylin
Timer |50 includes the timer solenoid |5I, motor
l 8
|52 and. magnetic timer lockswitch 1| 53.y Asso
| 1.' -Usually the -powerf »source- provides >current
at about 800fvolts and 3000 cycles in »the-heating
v» kciated with this timer areïthe-.timer on-relayï` |54
. and, timer. on-relay<~switch |55. LA-»switch larm
|56 is movable to».‘.‘on”.position»at switchfcon
tact element |51 andzto 1“oiT”.-position.atswitch
contact element |56. Similarly in ktimer _|60 is
included.- the solenoid. |.6|, motor |62, and mag
neticlockfswitch |65. Associated with this timer
|60 are timer on-relay |64, timer on-relay switch
‘» »Havingin mindthe complete organization' with
associated electrical and mechanical ~features`,th'e
operation of the «furnace control follows. ` The
side and» rear panel doors are closed, closing door
switches |19. The water cooling system is turned
- on, this »resulting »in closure of 1 pressure switch | I1
`and flow switch I4 I. ' The main switches' | | 5 are
"|55 and a switch arm |66imovable to “on” posi-‘
>tion’ Contact element ‘at Y|61 and “off”-position
vthen- closed, current flow being indicatedby‘the
Icontact element at I 68. " The timer-section D also
" VariousV current flow indicating lamps H6, ||8
'~ includes the tripping solenoid 85 -for operating the
and |36. Illumination 'of~ lamp |36~indicates a
mytripping latch, and> pilot lamp |10 for indicating
closed-»circuit through anti-reset relay" |29, by way
"completion ofthe heating cycle.
15 of Vnormally closed'load switch elements |0|b and
' The timer circuit is'traced from the sequence
“ selector switch |40 through parallel lines |11 and
` |12, including timer solenoids 15| and 16| -re
spectively, to the main »line ||2.
A 8b. ~».Simultarieously,anti-reset re1ay'swìtch`es`l3l
~ and |32'are closed/thus locking the'anti-reset
relay-'closing and lconditioning the‘circuits for
To maintain
application of voltage on the starter section B
- power after opening of sequence switch |48, taps
and theV timer section D on Vintroduction of the
Yare made at |13 and |14 on lines |1| and |12
~ workpiece.
respectively at points between the sequenceswitch
The workpiece is now inserted in `the'furnace
.1|48 and solenoid coils |51 and I5! respectively,
chamber causing the closure-of load switch ele
these tap lines leading through the timer
ment |0|a and thereby applying voltage to point
r>switches |53and |63 respectively and :a common 25 |44 and starter -section B and timer'section'D.
-return line |15 to the tap point |44 between B
VVBefore the workpiece has passed completely
- and C section.
Line |15 also supplies power to
over load switch element I0 | a itengages the ejec
tor rod, thus actuating the arm of load‘switch
8. This switch'has'two circuit contact* elements
6a and '5b which are simultaneouslyactuated,
normally open switch element 8a serving Aon c10
the timer switch arms |56 and |66. The timer
on-relay coils |54 and |64 are connected to the
main line ||2 and to points intermediate the
“on” timer contacts |51 and ‘|61 and the corre
sponding motor. The tripping solenoid 85 con
sure to maintain a voltage on the starting‘and
nects to the main line ||2 and to the “o ” timer
contact elements |50 and |68.
`Associated with timer section D is vthe main
contactor relay | 8| with heat-on pilot lamp |82
connected in parallel therewith. Circuit connec
tions with the timer section are made by exten
sion of timer line |15 from point |11 through
load switch 1, furnace panel door switches |19 40
associated with various side or rear panel-doors, '
on-relay timer switches |65 Vand |55 to point
|80 on the relay |8|. Also the mainline |~‘|2 is
extended from point |83 through point |15‘Iand
starter switch |84 to the main relay |8|. »A
~‘pilot lamp IBS-indicating complete insertion of
the workpiece connects the power side of the
panel door switches |19 with the main line ||2.
The high-frequency section'y E includes Athe
main contactor relay switches and a~rectifying
circuit for supplying direct current for operation
ofthe high-frequency contactor operating coil.
There are two main contactor» relay switches |90,
|9| and the previously mentioned switch |21.y in
Ythe starter section B, also operated by the relay
'The rectifying circuit is made as a conventional
bridge |92 and is comprised in the» four branches
|93, |94, |95 and |96 with copper oxide or equiv
alent elements inserted, one in each branch, with
such polarity as to produce a direct current po
tential at points |91 and |90, yas indicated. Al
ternating current is led to points |99 and 200
--on'the rectifier from main line ||2 at |16 and
timing circuits irrespective of the action of load
switch |0I. Opening of either orboth 8b~or |0| b
shifts- the anti-reset relay circuit entirelywthrough
anti-reset relay switch '|3I, so that should the
power be _withdrawn from this _relay'permitting
opening Vof the switch ISI, it cannot again be
closed unless both load switch contact elements
8b and |0|b are closed,'this requiring complete
unloading ofthe furnace.
' The workpiece is now moved to the rear end 'of
the furnace chamber `closing load switch 1 inthe
timer D section.
The starter button 42 is now
pushedin bringing about closure successively of
starterswitches |25,` |24 and |84, the closure of
switch' |24 being momentary. On the closure of
switches |25 and_| 24, a closed circuit is at once
established through normally closed main con
tactor relay switchV |21 `and the pilot contactor
relay |2| with its associated lamp |26. There
upon the two pilot contactor relay switchesff|22
.and |23 are closed, switch |23 locking the pilot
_relay |2|1c1osed since starter switchv |24 is closed
only _momentarily vduring the hood yclosing move
_ment _Also power is _applied _by way ofswitch'
-| 22 to the sequence switch |48.
The system of circuitsisnow conditioned for
vinitiation of. aheating cycle. This will develop
(ill when` the sequence switch- |48 which rcontrols the
_sequence of powerapplication `in the furnacebank
`establishes a closed circuitto the timersection
D. When this occurs timer solenoids |5| and |'6|
energized, locking switches |53 and |63 are
. from the C-D circuit |15 at point20l, the re ci
.closed,.timer switch arms :|56 and »|06 `moveto
-sultant tap line including inseries a resistance
on-position at contact elements y|51 and. |61re
-cut-in combination of a resistance 262 Aand nor
spectively and motors A|52 and '|62 function to
mally closed by-pass switch 203 on the resista-nce,
start the timing cycle. Simultaneously on-posi
and the main contactor relay switch 19|. The
-rectiñed circuit connects in series the main con
tion-relaysI |54 and l| 64 are energized, closing on
tactor relay switch |90 and they high-frequency
contactor operating coil 1204. Energization> of
lmagnet coil 204 closes the switch 205 of the high
»frequency high-voltage circuit 206 'includingf'the
«power source 201, capacitor-208 and heating coil
relay‘switchesL | 55 and |65, and since load switch
1, panel-door switches |19 and starter switchl |84
lare already closed, power isat once supplied from
circuitl point |44 between sections B land C
lthrough line |15, and from main line ||2-tò-the
2,4o5,985 v
contact with'any part of theffurnace with >.con-i 'i
main contacter relay |8| and its associated signal
lamp |82.
sequent damage is remote.
The particular structure shown and described
AThe energization of relay |8| closes main con
for accomplishing the objects of the invention
have been found to be efñcacious and usable.
tractor control relay switches |90 and |9|, and
opens switch |21 in the'starting section circuit.
However, itis apparent that modifications of th'e
The effect of opening switch |21 is to de-ener- ,
invention as described may be made to meet spe
cial conditions ef use and hence I do not desirel
to be limited to the specific illustrated means ex
cept in so far as required by the scope of the .
claims as hereto appended,
gi'ze pilot contacter coil |2| and cause the open
in'g of pilot contacter relay switches |22 and |23,
thus breaking the circuit through the sequence
switch. Additionally, closure of main contacter
relay‘switch |9`| closes a circuit from point 20|
on power line |15 through` the resistance cut-in
switch 203 to point |99 on the rectifier |92, thus,
applying a voltage at point 200 from main line
What is claimed _isi-
coil having a feed opening foi-,insertion vof a
source and coil, a relay circuit controllingthev
functioning of said circuit, including a vrelay
switch |90 to energize the high-frequency con
tactor coil 204. Thereupon, the switch 205 in
the main induction heating coil circuit is closed
and power from the source 201 _is applied to
heating coil |1.
`On completion of the heating cycle either timer
switch, closurek means for closing said coil feed
opening, and single means for closing said relayswitch and closure means, said closure means->
being adjustable independently of said relay
2. In induction heating apparatus, aheating coil
having a feed opening for insertionof av work
switch contact arm |56 or |66 breaks contact at
and |65, thus disconnecting relay |8|` and open
ing the main circuit and stopping the application
of power. In addition, timer switch contact
` workpiece, a power source, ’a circuit including said ,
||2, creating a direct current voltage at points
|91 and |98 which is effective through closed
elements |51 or |61 and opens relay switches |55
1. In induction heating apparatus, a’heating-
a power source for supplying power to-'said
25" piece,
coil, iiuid pressure means laterally movable rela
arms |55 and |66 engage contact elements |58
tive to the coil axis to form a yieldable feed
opening closure adjustable to werkpieces of dif- c,
ferent diameter, said means having pressure re-. ,
and |68 causing functioning of tripping solenoid
lease mechanism and means operably connected
85 to open the clamping bars 21 and star-ter
switches |25 and |84.
The workpiece may now
be removed from the furnace by actuating of the
foot pedal and/or application of tongs.
with said closure means but capable of move
ment independently thereof for controlling said
fluid pressure means.
3. In induction heating apparatus, a heating ,
From the description of the structure and of
th'e electrical circuit and connections as herein 35 coil having a feed opening for insertion of a work
piece, a power source and circuit including a
above made, the particular utility of the inven
switch for supplying current to said coil, a con
tion may -now be apparent. ~Operation of the
trol circuit including a fluid pressure operated
push button 42 to the latching point opens the
switch and means for closing said power circuit
valve 4| to permit air under pressure to enter
the closure cylinders 24 and at the same time 40 switch, closure means for the coil feed opening,
said closure means comprising two opposed, lin
introduce pressure to the switch |84 to make
possible energization of the main contacter relay
|8| and consequent activation of the power source
control relay 204. Switch |25 is closed just prier
to the latching of lthe button so that in the
early movable closure elements, and ñuid pres
sure means for closing said control circuit switch
and closure elements.
4. In induction heating apparatus', a heatingv _
latched position this switch remains closed, con
tinued pressure on the button causing overtravel
of the flange 61 to close switch |24. When pres
coil having a feed opening for insertion of a work
piece, a power source, a circuit includingrsaid
source and coil, a relay circuit controlling thel
sure means for closing said coil feed opening, and
functioning of said circuit, -including a relay
sure on the button is released it returns part way
to the latched position, opening switch |24 whose 50 switch,
a starter
to said switch
relay circuit
and circuit
to permit
energi- .
action is thus termed “momentary” It is point
ed out that these three switches are closed in time ' v zation of the relay circuit and relay switch, clo
It is also noted thatthe lfunctioning '
of switch |84 is fully dependent upon the appli
cation of pressure to the holding cylinders 24.
However, due to the fact that the holding means
involve fluid pressure with its yieldable charac
teristics it is also apparent that the functioning
of switch' |84 is not dependent upon the degree of
movement of the workpiece-engaging rollers 3|
so that switch |84 functions irrespective of the
size of the workpiece inserted in the feed open
ing. This relationship also permits the heating
of a workpiece of such length as to extend out
wardly appreciably beyond the rollers 3|, in
which position the rollers are spaced from each
other by the inter-position of the workpiece. It
is pointed out further that in the case of a long
workpiece which is being subjected to a heating
treatment it may be possible to remove the work
piece before the heating cycle is completed but
that, if such' removal is made, the piece is effec
tively grounded until it is well outside of the ma
chine and the chances of its making electrical
single means for closing said starter switch, relay
switch and closure means.
5. In induction heating apparatus, a heating
coil having a feed opening for insertion of a
workpiece, a power source, a circuit including said
source and coil, a relay circuit controlling the
functioning of said circuit, including a relay
switch, a starter switch and circuit operatively
connected to said relay circuit to permit ener
gization of the relay circuit and relay switch, clo
sure means for closing said coil feed opening,
65 single means for closing said starter switch, re
lay switch and closure means, means for estab
lishing a heating cycle in said heating coil on
closure of said starting switch, and means for
disconnecting said starting switch, relay switch
and closure means on completion of said heating
6. In induction heating apparatus, a heating
coil having a feed opening for insertion of a
workpiece, a power source, a circuit including
said source and coil, starting means for initiating
a heating'cycle in said circuit, closure means for
said coil’feed‘opening, and single means’ for ener-gizing successively saidy starting "and closure'
7. In induction heating apparatus,- a heating ,
coilhaving `a feed 'opening for insertion of ya
opening only on removal ofthe workpiece during>
the period of switch closure.
12. In induction heating apparatus, a heating
coil having a feed opening for insertion of a
workpiece, a power source for’supplying current
to said coil, a control circuit for making said power
workpiece, a power source, a circuit including said
sourceiand col-.starting means for initiating a
source eifective in said coil during a heatingY
cycle, holding means movablelaterally in rela-V
heating cycle" in saidpcir'cuit, closure means for
tion to the coil axis into engagement with a worksaidî‘coil feed opening,` single means for acti 10y piece
positioned insaid'coil wìtha section there-,
vatin'g vsaid starting and closure means, andanteofïextending
out of the feed openingpenergiaá`
matic timing means for bringing about deener
able means for actuatingsaidholding means, andY i
gization of thev starting and. closuremeans.> on
movablemeans for energization of saidfenergize
completionî of the heating cycle.
means .and control circuit,` said> holding
8. 'In ‘induction heatingapparatus, a heating
means being adjustable automatically to work
coilï‘havi'ng a feed opening` .for insertion of a
pieces Aof Vdifferent diameters and` operable only workpiece; a power source, a circuit including said
during the heating cycle.
source-~ and coil, "starting means for initiating-a
13. In induction Iheating apparatus, a heating.
heating' cycle'in said circuit',v >closure means `for
said‘c'oil feedopcnin‘g; and 'single means for »ac-' 20 coilhaving a feed opening for insertion of a work
tivatingv said v‘starting and' closure means, said »
starting means including" a device for restoring
saidvsingle means to pre-actuating position.
9.`1nv induction‘heating apparatus, a heating
piece,v a power source, la circuit .between rsaid
source and coil including a switch, a controlcir-` -
cuit for bringing about closure of said switch, and
closure> means-for. said .coil feed opening, said»
control circuitincludingmeans ffor preventing.`
closure of said sourcecircuit.switch-until. clo
coilhaving' ’a ‘feed ¿opening for insertion of a
workpiece,->` a powïer source, and'controlicircuit
connected to 'said source and coi1.,'andclosu're
means for closing said/coil: opening effective only
upon‘energizationof said control means, said clo
sure `4means' forming'a ground connection to the
sure ofthe feed opening is under wayn
14. vThe combination-according to claimv13 but
including additionally- means for preventing re
lease ofthe closure means >during a heat cycle.
workpiece.' "
15. In induction heating apparatus, a heating
coil having a feedopening for insertion of a work-~`
10.' In induction" heating apparatus, a heating
piece, `a power source forr supplying‘currentto '
coil having'a feed opening'for insertion "ofi a
workpiece, a power source for'supplying current
said coil, switchV means »f-for establishingfñow of ~
current from the source to thecoil, a‘control
tosai‘d'coilfa circuîtbetween‘said coil -and Source,
circuitfor causing closureof saidswitch means,-
a `relayi switch 4in saidcircuit', a 'control circuit
including' ,a starting 'switchan'd .a relay" coil for
closure means for closing said «coil lfeed opening'
initiating'a heatingl‘cycle" in 'said heatingv coil
by kclosure of s‘aidrelay switch, a closure means
foî‘"`said"feed opening'and me‘ans‘incorporated in
means to close rsaid opening, and `single movablev
said 'control"circuit for. 'activating saidl closure
and energizable meansforA actuating saidclosure
means for effecting energizatíon'of said energiz
40 able means and control circuit.
, meansfonfclosure'ofthestarting switch" and re
leasing s`aid closure îme'ans'at 'the end of the cycle.`
11; 'In' inductionmheating"apparatus,~ a heating’
coil having a feed opening for insertion of 'a work- .
piece,‘"'a ‘power’ source ‘for' supplying" currentrto
said coilßswitch' means controlling> current' sup-4
ply ’.from..said source,""holdingV means for 'yield`-V
ably'eng‘agingî'a workpiece extending within and
without said ' feed opening, l‘energi‘zable' means .for
actuating >`-`said ‘holdin‘gî means, .and‘ movable
mèans'for‘îenergization ‘of said energizable means'
andclosure of-'saidíswitch‘means, saidholding '
means' >automatic'ally ""mo'vingtto" close saidn ‘feed '
16. In induction heating apparatus, a heatingV
coil having a feed openingifor insertion of a work
piece, a power sourcel for supplying current to'
said coil,f switchameans for establishing ilow- of
current fromthe source to the coil, a control.
circuit for causing closure- of said switch means,v
closure means for closing said coil feed opening
and energizable means foractuating said closure’
means to close-said-openingfand single-movable means-` for effecting - energization ofy said energiZ-I’
able means .and control circuit, said control cir
cuit being dependentuponsupply of power to the
closure means for closure'of the switch means.
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