US3438426A - Ingot withdrawal means for continuous casting - Google Patents

Description

R. H. PARFIT A ril 15, 1969 INGOT WITHDRAWAL MEANS FOR CONTINUOUS CASTING Sheet 1 of 2 Filed Feb. 15, 1967 INVENTOR RAYmem: H PAlzFvr April 15, 1969 R. H. PARFIT 3,438,426

INGOT WITHDRAWAL MEANS FOR CONTINUOUS dASTING Filed Feb. 15, 1967 Sheet 2 of 2 iNVENTOR RRYMuNb H. Pmrl'f BY 7 w a c fl wzzw ATTORNEYS United States Patent Ofice 3,438,426 Patented Apr. 15, 1969 U.S. Cl. 164-282 4 Claims ABSTRACT OF THE DISCLOSURE An ingot withdrawal mechanism for a continuous casting plant, in which the ingot is withdrawn from the chill mould horizontally or near-horizontally in a series of intermittent steps with intermediate dwell periods by means of a motor-driven Geneva mechanism whose output shaft drives a pair of pinch rollers gripping the ingot. The Geneva mechanism is provided with a positive interlock to hold the slotted driven wheel stationary when the eccentric driving pin is disengaged from the slots of the driven wheel.

Background of the invention This invention relates to the field of the continuous casting of metals, using apparatus in which the liquid metal is fed from a furnace, ladle or other container into an open-ended chill mould whose casting axis is horizontal or near horizontal at the discharge end from which the solidified or partly-solidified metal is withdrawn intermittently as a continuous ingot.

It has been proposed to impart the intermittent withdrawal motion to the ingot by starting and stopping a motor driving the ingot withdrawal means; or alternatively as in British patent specification No. 812,356 by connecting the withdrawal means to the ingot during a portion only of a reciprocating cycle.

The former method has the disadvantage that the acceleration is not easily controlled and may snatch the ingot at the start of the withdrawal, causing rupture of the ingot skin in the mould if used at other than very slow speeds.

The latter method can produce a smooth low acceleration movement, but relies on engagement and disengagement of the gripping mechanism under high temperature conditions.

It is an object of the present invention to provide an improved cycle of intermittent withdrawal from the mould.

Summary of the invention According to the present invention, in an apparatus for the continuous casting of metals providing intermittent withdrawal of the newly-cast ingot from a horizontal or near horizontal mould (inclined at less than 45 to the horizontal), the ingot is gripped by one or more pairs of withdrawal rollers which are connected to the rotary driven component of a Geneva mechanism, the rotary driving member of which is driven by a motor. The Geneva mechanism is a well known mechanism for deriving an intermittent rotational output movement from a continuously rotating input member.

The use of the Geneva mechanism in this way has a number of advantages. The intermittent movement imparted by it to the ingot is sinusoidal in character, giving the smoothness of motion which has been found desirable in continuous casting. The movement of the ingot is positive and precise; there can be neither over-run nor run-back. The ratio of movement time to stationary time can be varied by varying the number of stationing slots on the driven wheel of the Geneva mechanism without altering the form of the movement. This is not, of course, possible with a reciprocating mechanism. The mechanism, apart from the rollers themselves which are in constant contact with the hot ingot, can be conveniently sited away from undue heat.

Brief description of the drawing The invention may be carried into practice in various ways, but one specific embodiment will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a side view of a horizontal-withdrawal continuous casting plant,

FIGURE 2 is a plan view of the withdrawal unit for the ingot, and

FIGURE 3 is an elevation of the withdrawal unit of FIGURE 2 seen in the direction of the arrow III in that figure.

Description of the preferred embodiment In the illustrated embodiment a continuous casting installation comprises a tundish 10 mounted on a frame 11 within a main vacuum enclosure 12, the pouring nozzle 13 of the tundish 10 leading into one open end of a horizontal mould 14 which is secured to the side of the tundish 10. The other open end of the mould 14 leads into a secondary vacuum chamber 15. A melting furnace 16 is pivotally mounted within the main vacuum enclosure 12 and can be tilted down to pour liquid metal 17 into the tundish 10 through the open top of the latter. The metal discharged through the pouring nozzle 13 of the tundish 10 into the mould 14 is chilled in the mould and emerges as a continuous horizontal ingot 16 which extends through the secondary vacuum chamber 15 and emerges via a vacuum gland 18 to be received on supporting rollers 19 outside the main vacuum chamber 12. The horizontal ingot 16 is gripped beyond the supporting rollers 19 by a pair of opposed pinch rollers 25 of a withdrawal unit 21 by which the newly cast continuous ingot is Withdrawn longitudinally in the horizontal direction from the mould 14.

The withdrawal unit 21 is shown in detail in FIGURES 2 and 3 and comprises a frame 22 supporting a pair of journal bearing 23 in which are journalled the shafts 24 of a pair of pinch rollers 25 constituting the withdrawal rollers by which the ingot 16 is gripped to withdraw it from the mould. The withdrawal rollers 25 are mounted one vertically above the other as shown in the drawings, so as to engage the top and bottom surface of the ingot 16.

The two withdrawal rollers 25 are coupled through individual worm gear drives 26 to a vertical intermediate shaft 27 journalled in bearings mounted on a cross member 28 of the frame 22, the worms being mounted coaxially on the intermediate shaft 27 for rotation thereby. The intermediate shaft 27 is driven through a chain or belt drive 29 by the output shaft 30 of a Geneva mechanism 31 which is journalled in bearings carried by a bracket 32 on the side of the frame 22, the slotted driven member 33 of the Geneva mechanism being mounted on .the output shaft 30 to drive the latter. The driven member 33 of the Geneva mechanism in this case has six radial slots 34 at equal angular spacings, these slots being entered successively by the eccentric driving pin 35 of the driving wheel 36 of the Geneva mechanism, which driving wheel 36 is itself mounted on a driving shaft 37 also journalled in bearings in the bracket 32. The driving pin 35 is fitted with a hardened steel brush to reduce Wear between it and the driven wheel 33. The driving shaft 37 is driven through a belt or chain drive 38 and a variable speed gear box 39 by an electric motor 40 mounted on the bottom of the frame.

Thus the two pairs of withdrawal rollers will be in termittently driven by the motor 40 acting through the variable gear box 41 and the Geneva mechanism 31 during the successive periods when the driving pin 35 is in engagement with a slot 34, alternating with dwell periods when the pin 35 has left one slot 34 and has not yet returned to enter the following slot 34. These alternate driving periods and dwell periods will produce intermittent successive withdrawal steps of the ingot 16 from the mould, the relative duration of the withdrawal steps and the intervening dwell periods being determined by the geometry of the Geneva mechanism 31. The overall fre quency of the cycles of withdrawal and dwell of the ingot may be varied by means of the gear box 39, without alteration of the amplitude of the steps.

The driving wheel 36 also'carries a coaxial disc sector 41 mounted for rotation with it, and the slotted driven member 33 is formed in its periphery with a number of concave recesses 42 respectively located at points of its periphery between the radial slots 34. During the portion of each revolution of the driving wheel 36 during which the driving pin 35 is out of engagement with any radial slots 34 of the driven member 33, the arcuate periphery of the rotating disc sector 41 is slidingly engaged in one of the concave peripheral recesses 42 of the slotted driven member 33 so as to hold the latter stationary and positively to prevent its angular rotation for the duration of the dwell period between successive angular stepping movements. As the eccentric pin 35 of the driving wheel 36 comes into engagement with the next radial slot 34 however, the disc sector 41 will turn out of engagement with the concave recess 42 of the slotted driven member 33 to free the latter for rotation by the eccentric pin through the next step.

The characteristic of the stepping cycle and the amplitude of the linear steps of the ingot 16 can be altered by replacing the relevant components of the Geneva mechanism by others having difi'erent characteristics.

For example a driving wheel 36 having its eccentric driving pin 35 at a different radius, and/or having two or more circumferentially-spaced eccentric driving pins 35, may be used, and the driven wheel 35 may be replaced by one having other than six slots 34, which may be of nonradial disposition, for example curved longitudinally.

If desired a second pair of withdrawal rollers may be provided to grip the ingot 16 beyond the first pair of rollers, this second pair of rollers being driven by a separate chain or belt drive 29 from the same Geneva mechanism .31.

What I claim as my invention and desire to secure by Letters Patent is:

1. Apparatus for the continuous casting of metals, comprising an open-ended chill mould and means for intermittently withdrawing a newly-cast ingot from the mould in a continuous length and in a direction inclined at less than 45 to the horizontal, which withdrawal means comprises a motor-driven Geneva mechanism driving at least one pair of withdrawal rollers between which the ingot is gripped, the rotary driving member of the Geneva mechanism being coupled to a driving motor for continuous rotation thereby and the withdrawal rollers being coupled to the slotted rotary driven component of the Geneva mechanism so as to be driven intermittently thereby.

2. Apparatus for the continuous casting of metals, comprising a chill mould having an open inlet end and an open withdrawal end, means for pouring molten metal into the open inlet end of the mould, and withdrawal means for intermittently withdrawing a newlycast ingot in a continuous length from the withdrawal end of the mould at an angle of inclination of less than 45 to the horizontal, which withdrawal means comprises at least one pair of Withdrawal rollers adapted to grip the ingot between them, and a motor-driven Geneva mechanism coupled to the rollers to drive them intermittently, the Geneva mechanism having a rotary driving member coupled to a driving motor for continuous rota tion thereby, a a rotary driven member journalled for rotation about an axis spaced from and parallel to that of the driving member and coupled to the withdrawal rollers by transmission means to drive the two rollers of each pair in opposite angular directions, a series of angularlyspaced, generally radially-extending stationing slots being formed in the rotary driven member and each stationary slot being open at one end at the circumference of the driven member, and at least one driving pin being mounted eccentrically on the rotary driving member for engagement in successive slots of the rotary driven member to turn the latter intermittently through successive angular steps alternating with stationary dwell periods.

3. Apparatus as claimed in claim 2 including means for automatically locking the driven rotary member of the Geneva mechanism against rotation during the said dwell periods, which locking means comprises a quadrant rigidly attached coaxially to the rotary driving member for rotation therewith, the rotary driven member being formed between the mouths of the stationing slots with a series of concave recesses in its peripheral marginal portion, and the quadrant being slidingly engaged in one of the said recesses to lock the driven member against rotation during each dwell period.

4. Apparatus as claimed in claim 2 including variablespeed gear transmission means operatively connected between the driving motor and the rotary driving member of the Geneva mechanism.

References Cited UNITED STATES PATENTS 1,442,021 1/ 1923 Workman 74-436 2,584,704 2/1952 Horn 164-282 X 2,815,551 12/1957 Hessenberg et al. 16483 3,158,522 11/ 19 64 Dreher 226152 X 3,290,734 12/ 1966 Wertli 164-282 J. SPENCER OVERHOLSER, Primary Examiner. R. S. ANNEAR, Assistant Examiner.

U.S. Cl. X.R. 226152

Images