US2141981A - Apparatus for casting metal - Google Patents

Description

Dec. 27, 1938. F. w. HARBORD Er Ax.

APPARATUS FOR CASTING METAL I 2 Sheets-Sheet 1 HTI/6,

www w m Dec. 5, 1936 Fil Dec.. 27, 1938. F. w. HARBORD ET AL APPARATUS FOR CASTING METAL Filed Dec. 5, 19.36 2 Sheets-Sheet 2 Patented Dec. 27, 1938 PATENT oFFicE APPARATUS FOR CASTING METALl Frank william autom' mi ,vente Hmm" London, England Application December 5, 1936, Serial No. 114,519 1 In Great Britain January 8, 1936 a,

6 Claims.

This invention `relates to apparatus for the direct and continuous production. from molten metal of billets, slabs, bars and the like and more particularly to the form and movement of the mould-elements utilized in apparatus of this f character. The mould cavity into which the molten metal is introduced is usually formed by two cooperating mould elements one or both of which are arranged to be continuously moved away from the pouring pointof the molten metal, the movable mould element or elements when of the kind to which this invention relates, beingconstituted by a series of segments and in order to prevent the escape of metal from the mould cavity until solidication has occurred yit f is evidently necessary 4for the successive seg-Y ments to be maintained in close contact with one another at their abutting ends during their movement near, and for some distance ahead of, the pouring point.`

- According to the principal feature vention this closeabutting contact of the segments is arranged to be ensured by causing the pressure which is exerted upon the movable element for efectmg its forward propulsion to be so exerted wholly or mainly at a point astern of the pouring point, this pressure being wholly or partly transmitted through vone or more segments at or astern of the'pouring ypoint to the segments ahead of this point. The propulsion pressure is ltinus transmitted-through the abutting ends of the segments at their contact with one another and the joints in the mould cavity at the points o engagement between the successive segments of the movable element are thus eiiectually sealed during the forward movement of the members.

Owing to the frictional opposition of each segment of the movable element to movement it will be evident that with this arrangement the protaneously, and is therefore shared between them;

and aspart of it vceases to act upon the leading segment of three,l it begins to act, upon the trailingsegment instead.

of the 1npulsion pressure transmitted from one segment (Cl. 2Z-57.4)

In one form of apparatus embodying the invention the mould cavity is'wholly in the moving mould element and formed of a channel in the top of each of a chain of segments guided to pass under a stationary cover through which molten metal is poured under a head; the segments pass round a wheel at each end, of the cover and are supported under the cover by rollers.

In other forms of apparatus the mould cavity is in the stationary mould element and is closed by a cover formed of a chain of segments above orbelow it.

The invention is illustrated by wayof example in the accompanying drawings of which Figure 1 is a view in side elevation partly sectional of one form of apparatus embodying the invention, Figure 2 being a view thereof in sectional elevation. Figure 3 is a. sectional view of a portion of the apparatus on the line III-III of Figure 2.

Referring now to the drawings it will be seen that the mould cavity I into which the molten metal is introduced is formed wholly in a sta'- tionary mould element. 2, the lower end of which is arranged to be closed by an endless line of segments 3, 3a, 3b passing around a wheel 4 and pressed outward by springs 44 against a semicircular track 45 at a radius which allows clearance between the ends of the segments. The upper stationary mould element is provided with an opening 5 through which the molten metal is introduced into the mould cavity I at the pouring point and the wheel 4, nearly coaxial with a semi-circular track is so located relative to this point that, as shown in Figure l, the line of segments passes off tangentially at a point astern 3 of the pouring point on to a series of guide rollers 6, 1 of which the rollers 6 are rotatably mounted on xed pivots, the pivots of the rollers 1 being arranged to be adjustable in any suitable manner so as to enable the vertical position of the jsegments in passing over these rollers to be adjusted relative to the stationary mould element The segments 3, 3a, 3b are in contact on rocker ends and the parts of the end faces of each segment adjacent to the mould cavity l are of such form or prole as indicated at 9 as to contactclosely with the corresponding parts of the end Afaces of the adjacent segments and the line or segments is arranged to be continuously driven vforward past the pouring point by mechanism which will now be described.

'I'he wheel 4 is of composite construction cornprising a pair of outer discs l0, Il and a pair of inner discs l2, I! these discs being all plvotally mounted on the shaft of the wheel. A worm wheel I4 is pivotally mounted on this shaft intermediate the inner discs I2, I3 and is arranged to be driven by a worm Il. the shaft Il of which is adapted to be rotated by an electric motor vor: other suitable source of power. Secured to the discs It, II, I2, I2 at spaced points around their peripheries corresponding to the ldistances apart of pins or studs l on the segments are a number of pairs of driving arms, each alternate pair being secured to the outer discs Il. II and the remaining pairs tothe inner discs I2, I2. As shown in Figure 2 in the case of the pair of arms I'I, Il for driving the segment 2a, the arm I'I is secured to the inner disc I2 by a bolt Il and dowel pins 2l. the arm Il being similarly secured to the inner disc I2 by a bolt 2i and dowel pins 22. lt will be observed that the bolts Il, 2| project through relatively large openings 22, 24 in the outer discs Il and II respectively so that the inner discs I2, I2 are capable of 'rotational movement to a limited extent relative to the outer discs III, II.

'Ihe next adjacent pairs of arms 25, 2l, that is to say, the pairs of arms alternating with the pairs of arms I'I, I2 are similarly secured to the outer discs I0, II by means of bolts 21 and dowel pins 2l. The upper ends oi' the driving arms project within corresponding slots formed in the segments so as to be capable of abutting against rollers mounted on the pins I at the rear of each segment.

It will thus be seen that in the position shown the segment 2a is being driven forward by the arms I1, Il.

'Ihe worm wheel ills provided with projecting pairs of arms 2|, 22 extending through openings 22 in the inner discs I2, I3 each pair of arms carrying pivotally mounted therein, as indicated at 34, a driving member 25. 2t respectively. The outer end 21 of the member 2l engages with the sides of an opening 22 formed in the outer disc I 0 while the inner end 38 of the member 2l engages with the sides of the opening 32 in the inner disc I2. Similarly the outer end Il of the driving member 32 engages with the sides of an opening 4I formed in the outer disc II-while its inner end I2 engages with the sides of the opening 23 in the inner disc I2.

The operation of the apparatus is as follows:-

The independent segments of the line forming the lower mould element or closing member for the mould cavity I are brought round in succession by the rotationv of the wheel 4 to the position shown as occupied by the segment 2b in Figure 1, at which position this segment contacts with segment 2a along the bottom of a narrow strip of the end face l below which each segment is always clear of the others and over which contact is complete when the two segments are in line. Up to this point the radius of the track allows a small clearance between the segments. Considering the threesegments 3b, Ia'and 2 immediately astern of the pouring opening `I, it will be seen from Figure l that the rear segment 2b is beginning to be engaged by the driving arms 25 on the outer discs III, II while the seg-v ment 2a. is positively engaged and driven by the arms I1, Il on the inner discs I2, I2. The front segment 2 is just ceasing to be engaged by the arms 22 on the outer discs I0, II and this segment 2 and the segments such as 2c in the line ahead of the segment 2 are under these conditions being driven forward by the thrust transmitted through the portions l of the faces of annee:

theirahuttlng endslotlmt thesefacesareheld closely in contact with one another with a pressure which is a maximum at the joint between the segments 2a and 2 and decreases in the forward direction at each successive joint between the segments with the falling off of the frictional opposition to their movement.

The segments at and ahead of the pouring point are thus maintained closely in contact with one another and form a substantially closed mould cavity I of sumcient length to ensure the formation of a billet from the molten metal near the front end of this cavity. jIt will be understood that the segments after passing away from the forward end of the mould cavity I are arranged to pass around a suitable guide track with or without a wheel or drum so as to return eventually to the under side of the wheel l.

The arms II, 22 not only enable the driving arms such as I'I, Il ofeach pair acting on one segment t'o adjust themselves automatically on ensuing with the segment so as to ensure uniform drivingpressuretobeexerted onthesegment by the two arms in the event of the Joint between adjacent segments not being accurately at right angles to the directionof movement but the members II and 22 pivoted on the arms 2|,22 also permit the outer discs Il, II torotate relatively to the inner discs I2, I2 to a limited extent as permitted by the clearance between the segments below 2b so as to ensure effective contact of adjacent pairs of driving arms with their respective segments 2b. 2a even if these segments are not of exactly the same length or if 4the driving arms are not exactly set.

The line of segments ahead of the pouring point may, if desired. be arranged to be guided laterally by members I2 which are preferably arranged to engage with the sides of the segment for a portion only of its length so as to permit the segment to takeup a slightly inclined position if necessary for completely closing the transverse joints between it and the adjacent segments.

In cases where, for rapid operation, a .long mould is used and the diderence in the lengths of segments when cold and when hot is consider able we provide means for ensuring that the segments shall be smoothly engaged by the driving arms of the wheels ahead ot them. According to one arrangement we arrange a star wheel near the point of engagement rotated so that it hastens the advance of segments when this is required. l

`In a modined form of apparatus embodying the invention and applicable in cases in which the length of billet or slab to be cast at one operation is limited it is unnecessary to provide for a series of mould segments to be continuously propelled past the pouring point, and a limited number of segments forming a series of suitable length can be arranged to be moved forward by means oi a body pressing upon a segment which starts at least the billet length astern of the pouring point, and propelled forwards by any suitable means. In most cases such a body may be a crossbar to whose ends hauling cables are attached. In one form of apparatus embodying arrangements of this character as applied to the propulsion of a line of mould segments containing the mould cavity and' adapted to travel past a stationary upper cover, two cables, one onfeach side of the line of segments, are attached at their ends to an equalising lever or its equivalent acting on a segment in the line at a distance astern of the pouring point, which is somewhat greater than the full travel required. Adjacent to the pouring point each of these cables passes round a suitable fixed guide pulley and is led to any suitable winding mechanism by the operation of which, as will be readily understood, the cables exert a tractive eiort on the segment on which their ends act, this segment during its travel forward thus effected propelling all segments in front of it past the pouring point, the forward thrust transmitted from segment to segment tending to maintain the joints between adjacent segments tightly closed and thus preventing leakage of the molten metal from the mould cavity.

The track upon which the line of segments is supported preferably comprises an inclined straight portion rising towards a summit astern of the pouring point continued by a downwardly inclined straight portion, the segments being supported throughout these portions of the track by suitable rollers.

After the full travel of the line of segments has been completed and the casting removed, the segments may be arranged to be returned t0 their original positions by another set of cables connected to what was previously the leading segment as will be readily understood.V

In an alternative form of track for the line of segments the latter may be arranged to form an almost complete endless band passing around suitable wheels or drums horizontally spaced apart from one another, the segments forming an upper line between the wheels or drums being supported upon suitable rollers where the segments pass underneath the stationary cover with which they cooperate to form the mould cavity. The ends of the cables are in this arrangement connected to a rear" segment which starts somewhat ahead of the pouring point and these cables pass around wheels coaxial with the said wheels or drums and following the line of segments as far as guide pulleys adjacent to the pouring point, the cables being led from these Pulleys to the winding mechanism. It willthus be seen that the tension exerted by the cables on the rear segment is transmitted round the track through the line of segments ahead of it and causes each segment to abut against the next adjacent segment with a pressure which increases to a maximum at the segments at the rear end of the line and is higher at the pouring point than at the front end of the stationary cover.

Similar arrangements may evidently be employed in apparatus in which the line of segments constitutes an upper cover or mould member cooperating with a travelling or stationary lower mould member and in all cases the-segments during the return or inoperative part of their path may be arranged to be cooled by any suitable means for this purpose.

The cable arrangements above described are more particularly applicable to casting apparatus in which ladies for the molten metal of relatively i large capacity are employed, the castings being produced in relatively short lengths.

The invention is not limited to the particular constructions and arrangements of apparatus described and illustrated which may be varied in many respects without exceeding the scope of the invention.

Having now described our invention, what we claim as new and desire to secure by Letters Patent isz- 1. Means for propelling a continuous mould element in a continuous casting machine, comprising at least two propelling devices including sets of driving arms arranged simultaneously to engage with the continuous mould element at successive positions on its path, actuating means for applying driving power, and diierential driving means, interposed between said actuating means and said propelling devices for distributing the driving power between said propelling devices, said diierential driving means comprising one primary element to which driving power is applied by said actuating means, and a number oi secondary elements operatively connected to said primary driving element so as to be diierentially driven by it and arranged to drive one propelling device each, so as to distribute the driving power applied to the said primary element between the said propelling devices.

2. Propelling means as claimed in claim 1, in which two sets of driving arms constituting said propelling devices are arranged to be rotatable and displaceable with respect to one another about a common axis.

3. Propelling means as claimed in claim 1, in which the continuous mould element is constituted -by a series of mould segments, and said two propelling devices are arranged to engage each alternate segment respectively.

4. Propelling means as claimed in claim 1, in which the continuous mould element is constituted by a series of mould segments, and two sets of driving arms for each alternate segment constituting said propelling devices are respectively fixed on outer wheels rotatably mounted on a shaft, two further sets of propelling arms for the remaining segments being respectively xed on inner wheels, said outer and inner discs being arranged to be respectively driven by the secondary elements of said differential driving means.

5. Propelling means as claimed in claim 1, in which the propelling devices are constituted by wheels carrying driving arms, and two such pro- `pelling devices are arranged to be rotatable about a common axis, the dierential driving means being constituted by levers the two ends of each lever being respectively connected with said two propelling devices, and a point intermediate the ends of each lever being connected to the primary driving element.

.6. Propelling means as claimed in claim 1, in which at least two propelling devices are constituted by coaxial wheels carrying driving arms and a substantially circular guide is provided near an end of the casting machine for guiding the continuous mould element in a curved portion of its path, a wheel arranged at the hollow side of the guide and spring means arranged on said wheel for resilientiy pressing said mould element

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