US2361101A

US2361101A - Metal casting apparatus

Info

Publication number: US2361101A
Application number: US508720A
Authority: US
Inventors: Robert K Hopkins
Original assignee: MW Kellogg Co
Current assignee: MW Kellogg Co
Priority date: 1943-11-02
Filing date: 1943-11-02
Publication date: 1944-10-24
Anticipated expiration: 1961-10-24

Description

Oct. 24, 1944. R* K HOPKINS. N 2,361,101

` METAL CASTING APPARATUS y Filed NV. 2, 1943 INVENTOR sumed, it is fed endwise with Patented Oct. 24, 1944 METAL CASTING APPARATUS 'RobertrK Hopkins,- New York, N. Y., assignor to The M. W.

Kellogg Company,

New York, N. Y.,

a corporation of Delaware Application November 2,1943, Serial No. 508,722.0v

l(Cl. 2257) 9 Claims..

. The present invention relates to the art of producing-cast metal bodies.

In the electric fusion method of producing cast metal bodies such as ingots, a consumable electrode containing some or all of the metal ingredients of the ingot to be produced, has one end submerged in a protective layer of iiux in a mold. Current discharged through a gap separating this electrode from the body of deposited molten metal creates a metal fusing zone, so that said electrode, as well as other metal ingredients which may be fed in this` zone, are fused and deposited as molten metal below the flux layer. This electrode passes through a, contact sleeve or nozzle which supplies metal fusing current to the electrode, and which extends into the mold above the iiux layer. -As the electrode is conrespect vto the contact nozzle to maintain a constant positional relationship between the current discharge end of the electrode and the surface of the deposited molten metal. As the level of the molten metal in the mold gradually rises, the level of the iiux also rises to the same extent. It is necessary, under these conditions, to raise the contact nozzle to maintain a predetermined positional relationship between the lower end of the nozzle and lthe upper surface of the ux. If the contact nozhot ux layer, the said layer may of the contact nozzle.

When the mold is of comparatively large crosssection, a., pilot control its lower end will be maintained a constant'predetermined-distance above 'the surface of the flux layer.` However, when the cross-section .of the mold is small, it is dicult to use the pilot control because 'oi the limited clearance aiorded by said mold.

One object of the present invention is to provide a new and improved control means which maintains a constant positional relationship between the contactnozzle and the ux layer in a mold, and which is entirely outside the mold cavity.

Various other objects of the invention will be apparent from the following particular description, and from an inspection of the-accompanying drawing, which shows somewhat diagrammatically partly in Vertical section and partly in front elevation a casting apparatus having nozzle control means embodying the present invention.

Referring to the drawing, there is provided a mold II) which maybe of any suitable hollow shape in accordance with the desired shape of the cast body toA be produced, but which is shown in the form of an upright cylindrical tube having an elongated cavity II of comparatively small cross-section. This mold I is desirably of a metal having high heat conductivity such as copper, and is provided with a jacket I2 for the circulation of a suitable cooling liquid therethrough. An inletpipe I3 for the cooling liquid is shown connected into the upper end of the mold jacket may be employed therein to move automatically the contact nozzle, so thatv .so that current I2. An outlet pipe (not shown) vfor the cooling liquid may be connected to the lower end of this mold jacket I2.

The lower end of the mold I0 may be closed by any suitable means, as for example a stool (not shown), also of metal such as copper, and also desirably hollowed to form a jacket for the circulation of a suitable cooling liquid therethrough.

The metal is produced and deposited in the mold I I! by the use of a iiux submerged electrode v device which may be of the general type shown in my U. S. Patent No. 2,191,479, issued Februaryv 27, 1940. For that purpose, there is provided a consumable electrode I4 extending in the mold I0. Electrode I4 may be solid and contain al1 of the constituents of the desired metal I5 or electrode I4 may be hollow and be made of some of the constituents of metal I5 while the remainder of the constituents are supplied through electrode I4 to the -fusion zone created at the discharge end of electrode I4 at controlled rates in the fluent form of granules, pellets, powders, and the like., "The rate of supply of electrode I4` and the rate of supply of the material in iluent form being adjusted to produce a metal I5 in the mold I0 having vthe required analysis.

The lower end of the electrode I4 is submerged in a oating layer or blanket I6 of flux of any suitable composition having the proper electrical and/metallurgical characteristics and is spaced above the upper surface of the deposited metal-|5 bya gap I'I.

This i'lux I6 refines the metal as it is produced, promotes `fusion of the metal, protects it against atmospheric contamias manganese silicate, calcium silicate, aluminum silicate, glass andthe like.

The electrode I4 and the deposited metal I5 are electrically connected in the same circuit, as it is discharged from said electrode, passes through the gap I1, and theresaid nozzle, but tight enough to maintain electrical contact between said nozzle and said electrode.

The electrical connection of the deposited metal I5 into the circuit of the contact nozzle to permit the feeding of said electrode through ing 35 in the mold jacket I2. This contact housing 35 is in slide engagement with the outer surface of the inner metal mold wall 36, and the thermo-sensitive element therein is in slide contact with this surface, or at least in close proximity thereto to react thermally'l upon changes in temperature in the mold cavity I I at the level of said element.

`The control device is advantageously of the' thermocouple type, so that the thermo-sensitive element in the contact shoe 35 would be the hot f junction or couple of the device, although as far I8 may be e'ected as for example, by grounding the metal walls of the mold I0.

The contact nozzle I8 serves not only as a means of maintaining a steady current feed to the electrode I4, but also serves as a feed guide for said electrode. The lower end of this contact nozzle I8 is-spaced a substantial distance above the upper level lof the ux I6 to prevent said nozzle from being destroyed by the intense heat of the superheated flux I8.

As the metal producing operation progresses,

the level of the deposited metal I5 as well as that ofthe flux layer I6 gradually rises. As the electrode I4 is consumed and the deposited metal I5 rises, said electrode is moved at a rate necessary to maintain the current discharge gap I1 constantin length. 'Ihis controlled movement of the electrode I4 may be effected in any wellknown manner, as for example through a pair of feed wheels 20 on opposite sides of the electrode I4 and in frictional engagement therelwith. At least one of these feed wheels 2li is driven from a motor 22 through a suitable reduction gearing, while the other wheel may be positively driven from said motor or may be merely an idler.

` Motor 22 may be controlled, for example, by the voltage drop across the gap I1 in any well-known manner,` as is common in the. electric arc welding and electric arc furnace arts, so that the feed wheels 20 are automatically operated and controlled to feed the electrode I4 as necessary to maintain a discharge gap I1 of constant length.

As the level of the flux I6 gradually rises, it is necessary to move the contact nozzle I8 upwardly to an extent necessary to maintain a constant positional relationship between the lower end of said contact nozzle and said flux layer. For moving the contact nozzle I8 upwardly, said nozzle is secured to a hoist 23 by.

any suitable means, as for examplethrough a clamp 24. This hoist 23may be moved verti:`

cally by any suitable means. Thus, hoist 23 may be moved in the manner indicated in the drawing through a pair of vertical 'feed screws 28 jthreaded therein, and journalled in suitable fixed bearings 21 arranged to hold these feed screws against .axial movement. The two feed screws 26 are driven in unison and in the same direction through a motor 28 and a speed reducing transmission between said motor and said feed screws.` This transmission, for example, may comprise worm wheels 30 keyed or otherwise af'- iixed to feed screws respectively for rotation therewith, and meshing with respective'worm wheels onthe shaft ofthe motor 28.

'As a-feature of the present invention, the op eration of the motor 28 is automatically controlled by means of a thermo-responsive control device .disposed entirely outside of the mold cavity II. This control device is desirably of the electric pyrometric type having' a heat sensitive element enclosed in. a contact shoe or houstive element in the contact shoe would be the resistance element of the device.

Connected to the contact shoe 35 is a conduit 38 through which the leads 31 from the thermocouple or junction extend. These leads 31 are sealed and insulated from the cooling liquid in the mold jacket I2, and connect into a control unit 39. This control unit 38 may be of any well-known type, in which the generatedthermoelectric current when increased in strength above a predetermined value, closes a switch (not shown) in the circuit of the hoist motor 28 and thereby operates said motor, and when it falls below a predetermined value opens this switch and thereby shutsoi said motor. The motor 28 for that purpose is connected to this control unit 39 by the leads 40.

Contact shoe 35 is positioned to maintain the bottom end of contact nozzle I8 the chosen distance above the Atop surface of the hot flux or slag I6. In operation, since the volume of metal as shown, the intense heat of the ilux is trans,-`

mitted to the thermocouple through the metal mold wall 36. This results in the generation of thermo-electric current above a predetermined value, and the consequent closing of of the motor 28. The motor 28 will therefore rotate in a direction to raise the hoist 23 through the feed screws 26 so that the contact nozzle I8 is raised. At the same time, the contact shoe 35 is raised in unison with the contact nozzle I8, so that when said contact shoe reaches that positionabove the intense heated area defined by the flux I6, at which the generated thermo-electric current falls below a predetermined. value, the motor 28 shuts down.

For eiecting Athe movement of vthe contact shoe By means of the construction described, the

lower end of the contact nozzle I8 is maintained at a constantpositional relationship with respect to the flux I6, soA that at no time will this contact nozzle become overheatedv or will it in any way dip` into said ux. y

The

feed device

20 and 22 for the electrode I4 may, if desired, be supported on the hoist 23 as shown. With this construction, theelectrode I4 will be moved upwardly with` the contact nozzle I8, but will still be subject to the control of the .Circuit tion with a control l nozzle I8 relative to the flux.

lrent discharge electrode of said contact nozzle layer of ilux,

feed wheels 20 according to the voltage drop across the gap I1, or according to any other regulating factor selected, so that the length of this gap will be kept substantially constant.

Although the invention is shown in conjuncby which the contact nozzle I 8 and the thermocouple conduit 36 are raised from a stationary mold I while the casting operation progresses,

35 may be kept stationary, while the mold I0 is lowered by some control device similar to that shown to maintain a constant positional relationship between the contact nozzle I8 and the ux I 6.

Also, in accordance with certain aspects of the present invention, instead of controlling the motor 28 by alternately turning it ofi'` and on, said motor can be regulated by controlling its speed to ymaintain the desired .position of the contact may be of the reversible type to permit the hoist 23 to be lowered for each new casting operation.

The reversing circuit for this motor 28 may be of anwtlfpe-Well-known in the art.

As many changes can be made in the above apparatus, -and many apparently widely diierent embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense. o.

What is claimed is:

1. A casting apparatus comprising a mold with a metal wall confining the mold cavity, a curadaptedy to extend into said mold with its lower end submerged in a layer of ux, a contact nozzle for said electrode adapted to extend into said mold above said ux,

a thermo-responsive element on the outside of said mold cavity adjacent to said wall, and means for translating the action of heat of predetermined intensity on said element into a corresponding motive force, whereby axial movement relative to said mold can be controlled in accordance with said force to maintain said nozzle a substantially constant distance above said ilux.

2. A casting apparatus comprising a mold with a metal wall confining the mold cavity, a current discharge electrode adapted Ato extend into said mold with its lower end submerged in a a contact nozzle for said electrode adapted to extend into said mold above said as far as certain aspects of the linvention are concerned, the contact nozzle I 8` as well as the conduit 38 with its contact shoe I6. This motor 28 A nozzle. and means responsive to the thermal reaction of the flux on said element for controlling the operation of said motor.

4. A casting apparatus comprising a mold with a metal wall confining the mold cavity, a current discharge electrode adapted to extend into said mold with its lower end submerged in a layer of ux, a contact nozzle to extend into said mold above said flux, a thermo-'responsive element onthe outside of said mold cavity adjacent to said wall, means for translating the action of heat of predetermined intensity on motive force, contact nozzle whereby axialvmovement of said relative to said mold can be controlled in accordance with said force to main'- ing said nozzle and said thermo-responsive element for movement in unison relative to said mold.

5. A casting apparatus comprising a mold with a metal wall conining the mold cavity, acurrent discharge electrode adapted to extend into said mold with its lower end submerged in'a layer of ux, a contact nozzle for said electrode adapted to` extend into said mold above said ux, control .means for automatically maintaining constant the positional relationship between said contact nozzle and the ilux in said mold, said control means comprising a thermo-responsive element on the outside ci?a said cavity adjacent to said wall, a motor for'causing relative axial movement between' said mold and said contact nozzle, and means responsive to the thermal reaction of the flux on said element for controlling the operation of said motor, and means interconnecting said thermo-responsive element and proximity said contact nozzle for ative to said mold.

6. A casting apparatus comprising a mold with a metal wall confining the mold cavity, a current discharge electrode adapted to extend into said mold with its lower end submerged in a layer of nozzle for said electrode adapted to extend into said mold above said iux. a shoe in slide contact with the outersurface of said wall, a thermo-responsive element in said shoe in close to said wall to react readily when the ux reaches a position near the level of said element, means for translating the action of heatl of predetermined intensity on said element into a corresponding motive force, whereby axialy movement of said contact nozzle relative to said ux, and thermometric control means for automatically maintaining substantially constant the positional relationship between said contact noz- -zle and the ux in said mold, said control means comprising a thermo-responsive element on the outside of said mold cavity adjacent to said wall.

3. A casting apparatus comprising a mold with a metal Wall conning the mold cavity, a current discharge electrode adapted to extend into said mold with its lower end submerged in a layer of ilux,a contact nozzle for said electrode adapted to extend into said mold above said flux, and control means for automatically maintaining constant the positional relationship between said contact nozzle and the ux in said mold, said control means comprising a thermo-responsive element on the outside of said cavity adjacent mold can be controlled in accordance with said force to maintain said nozzle a; substantially constant distance above said ilux, and means interconnecting said nozzle and said shoe for movement -in unison relative to said mold.

7. A casting apparatus comprising a mold with a metal wall confining the mold cavity, a current for causing relative axial movement mold and said contact nozzle, and means refor said electrode adapted said element into a corresponding movement in unison relsponsive to the thermal reaction of the ux on said element for controlling the operation of said motor, and means interconnecting said shoe and said nozzlefor movement in unison relative to said mold.

8. A casting apparatus comprising a mold with an inner metal wall and an outer wall'forming therebetween a jacket for the circulation of a cooling liquid therethrough, a current discharge electrode adapted to extend into said mold ,with its lower end submerged in a layer of flux, a contact nozzle for said electrode adapted to extend into said mold above said flux, and control means for automatically maintaining constant the positional relationship between said contact nozzle and the flux in said mold, said control means comprising Va thermo-responsive element in said jacket adjacent to said inner wall, a motor for causing relative axial movement between said mold and said contact nozzle, and means responsive to the thermal reaction of the ilux on said element for controlling the operation of said motor.

9. An apparatus for producing ingots comprising a mold, an inner metal wall and an outer wall forming therebetween a jacket for the circulation of a cooling liquid therethrough, a current discharge consumable electrode adapted to extend into said mold with its lower end submerged in a layer of ux, a contact nozzle for said electrode adapted to extend into said mold above said ux,- thermocouple control means for automatically maintaining constant the positional relationship between said contact nozzle and the flux in said mold, said control means comprisingv in a direction to raise said nozzle, and means interconnecting said nozzle and said shoe for controlled movement in unison.

ROBERT K. HPKms.