US3386494A

US3386494A - Continuous casting vibrating system

Info

Publication number: US3386494A
Application number: US528533A
Authority: US
Inventors: Douglas C Yearley; Henri H Audi
Original assignee: Phelps Dodge Copper Products Corp
Current assignee: Phelps Dodge Copper Products Corp
Priority date: 1966-02-18
Filing date: 1966-02-18
Publication date: 1968-06-04
Anticipated expiration: 1985-06-04

Description

June 4, 1968 YEARLEY ET AL 3,386,494

CONTINUOUS CASTING VIBRATING SYSTEM Filed Feb. 18, 1966 2 Sheets-Sheet 1 INVENTORS DOUGLAS C. YFARLEY G HENRI H. AUD

A T TORNEY-S.

United States Patent 3,386,494 CONTINUOUS CASTING VIBRATING SYSTEM Douglas C. Yearley, Westfield, N.J., and Henri H. Audi, Elmhurst, N.Y., assignors to Phelps Dodge Copper Products Corporation, New York, N.Y., a corporation of Delaware Filed Feb. 18, 1966, Ser. No. 528,533 7 Claims. (Cl. 164-260) or during a portion of the casting period. Sticking of the cast in the semi-solidified state to the mold surfaces is overcome or eliminated by such vibration, which also improves and controls the surface quality of a casting and its grain structure. The displacement of the components being vibrated are usually of quite limited amplitude, usually not exceeding A inch, with frequencies of several hundred to several thousand cycles per minute.

The mode of vibration can be sinusoidal, some nonlinear relation other than sinusoidal, and by a periodic impact as by a blow from a spring-loaded trip hammer or the like.

In tube casting, particularly tubes of materials comprising copper and copper alloys, the-re is need for a wide range of different modes of vibration in order to ob tain optimum casting qualities and grain size, in additon to avoding o-r overcoming sticking.

The principal objective of the present invention is to provide an improved continuous casting system capable of vibrating in a wide variety of modes and adjustable as to the frequency and amplitude of each of its vibration modes.

According to the present invention, a mold is mounted on a first platform which is releasably attached to a second platform. Spring means are positioned between the two platforms and supports the first platform upon the release of the rigid connection. Controllable vibrators are operatively connected toeach platform. The mold is vibrated in accord with -a plurality of possible vibrations of the first platform alone, or in combination with the second platform rigidly or resiliently connected thereto.

These and other features and objects of the invention will be apparent from the following description of a preferred embodiment of the present invention as illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is the front elevation of a vibrating support for a mold;

FIGURE 2 is a side elevation of the bottom portion of the support as viewed along section line 2-2 of FIG- URE 1;

FIGURE 3 is a sectional plan view as viewed along section 33 of FIGURE 2 with certain portions shown in dot and dash lines representing portions located above the sectional line; and

FIGURE 4 is a sectional elevation as viewed along sectional line 44 of FIGURE 2.

In the drawings, like reference characters refer to identical parts.

The vibrating mechanism of this invention is useful in any continuous casting system where continuous or interrupted relative vibratory movements are desired between the mold and the casting. Our invention may be used in the casting of dense objects, such as rods, or hollow objects, such as tubes. It gives special advantages for objects of copper or copper alloys as their surface and grain size may be controlled by use of it.

According to the preferred embodiment of the invention we provide a plurality of vibration modes that are controlllable, even during the actual casting of the objects, by relatively simple adjustments.

As shown in FIGURE 1, a mold 12 is supported on a platform system 11. The platform motion 11 is responsive either to one or two vibrators or to both. One of the vibrators, 20, provides a very high frequency sinusoidal vibration and effects vertical vibratory forces on the platform. Another vibrator, 21, is connectable to the platform system 11 and provides low frequency non-sinusoidal vibrations which effect an upstroke or vertical rising of the platform that is different in force or duration to the downstroke.

A second, auxiliary platform system 10 is releasably connected to platform system 11 and either rigidly or resiliently support the mold 12. Platform system 10 is connected to a third vibrator 25. The mold and vibratoiy apparatus is supported on a rectangular frame formed from channel beams 36.

Referring now to the apparatus as illustrated in greater detail in FIGURES 2 and 3, upper platform system 11 is formed by a pair of elongated rectangular plates 31. Plates 31 are spaced sufliciently apart to provide a space beneath the mold 12 for passage of the bar or tube (not shown) to be cast in the mold. The withdrawal apparatus (not shown) is located beneath the mold 12. The usual apparatus for supplying molten metal to the mold 12 (not shown) is located above mold 12. Mold support plates 31 are welded to the inner pair of cross-bars 38a, perpendicular to plates 31. Cross-bars 38a are welded to a pair of bottom plates 39 spaced outwardly from plates 31. A second pair of cross-bars 38 is welded to the bottom of plates 39. A pair of plates 40 spaced beneath and parallel to plates 39 are welded to the opposite face of

bars

38 and 38a. Four antifriction ball bearings are provided in apertures in the plates 39 to receive the four posts 14. The four posts 14 are respectively guided in vertical movement by four L-shaped brackets 16 each having an enlarged cylindrical end portion 15 within which are ball bearings or roller bearings for easy axial sliding therein. A similar roller bearing carrier 15a is provided to guide the lower end of rods 14, see FIGURE 4. L-brackets 16 are connected to the lower plate assembly 10 by bolts and nuts 17.

The lower plate assembly 10 is formed from a pair of spaced rectangular plates 30 welded to a pair of crossmernber plates 34 which in turn are carried by pinions 42. Pinions 42 are rocked on a curved path approximately vertical by vibrator 25 through a pair of

linkages

26 and 26a spaced on opposite sides of the channel member 36. The linkage arm 26a is oscillated back and forth a few degrees on a curved path by means of an eccentric cam on vibrator 25. Each of the linkages 26 is at its end pivotally attached to channel 36 (which is channeled to accommodate the generally vertical motion of pinions 42) and this converts the vibrator motion into generally vertical motion of the pinions 42. In order to effect symmetrical forces generated by the vibrator 25, a connecting rod 44 connects the pinions assembly on the right with a comparable pinions assembly on the left side of the lower plate assembly 10. Rod 44 is pivotally connected by connectors 46 at one end to linkage 26 and at the opposite end to a triangular plate 48.

Plate assembly 11 is resiliently supported on the lower plate assembly 10 by four springs in opposing pairs, 13A

and 13B. Spring pairs 13B are mounted on a plate 32 which in turn is bolted to plate 30 of the lower platform assembly 10. Spring pairs 13A are mounted on similar plates 32a which in turn are mounted by bolts to crossplates 34. The upper end of springs 13B are support to the lower faces of plate members 41 of plate assembly 11 and spring pairs 13A support plates 40. Platform 11 is displaceable vertically, and, in conjunction with platform 10, horizontally. Two high frequency vibrators 20 are attached to the bottoms of support plates 31.

Platforms 11 and are arranged also to be rigidly connected by releasable connections. Bolts 18 and

lower nuts

19 and 19a rigidly connect lower plate 30 to upper plate 41. When the bolts 18 and nuts 19 and 19:: are in place, as shown, the upper platform assembly 11 is rigidly connected to the lower platform assembly 10.

As shown in FIGURE 1, a vibrator 21 is connected to the upper platform assembly 11 by means of struts 22. Struts 22 have bolts 50 which may be screwed into crossmembers 38 to connect platform assembly 11 to the vibrator 21. The vibrator 21 may be actuated by hydraulic means (as shown in FIGURE 1) or by mechanical means (not shown) to generate vertical vibrations at a low frequency, on the order of 100 cycles per minute, with a stroke on the order of 4 inch to 3 inches. When using hydraulic means, vertical movements of vibrator 21 are detected by positionable limit switches 23 and adjustable trips 24 for actuating reversing switches (not shown) to control its stroke length and period of vibration. Preferably, the speed of movement in one direction is different from the speed of movement in the other direction. In the art, this is known as the vibrator speed ratio. The speed in the upward direction in relation to the speed in the downward direction is made adjustable by means such as a pressure valve (not shown). Thus, vibrator 21 develops motions on the upper platform level 11 which are non-sinusoidal in nature, being effective at rapid upward motion with a slower downward motion. The downward motion is preferably adjusted to be of the same order of linear speed as the linear movement of the cast being Withdrawn from the mold 12.

There are five modes of vibration to which mold 12 may be subjected with respect to amplitude and frequency of vibration. There are three sources of vibration forces. Vibrator 25 develops a sinusoidal reciprocal vibration by the linkage 26 to effect an approximately vertical vibratory displacement of platform 11. Vibrator 25 is preferably adjusted to vibrate within the limits of 100 to 2000 cycles per minute with an amplitude varying between 0.006 to 0.250 inch. The instantaneous displacement X, in inches, may be represented according to the following formula:

X=a sin W 2 where W is the angular speed of the vibrator 25 in radians per second; a is the stroke in inches; and t is time (seconds).

A pair of vibrators are symmetrically connected to plate 31 to produce vibrations on the upper platform only which rests on springs 13A and 13B. The vibrators are not in contact with the lower platform assembly 10 at any time. The vibrators 20 may be selected from any of the usual high frequency vibrators operated by pneumatic or electrical means for effecting vibrations in the order of 2000 to 6000 cycles per second. The vibration forces are oriented to the vertical and may be represented by the following relation:

P:F sin W t (2) where P is the instantaneous force in pounds on the upper platform assembly 11; F is the maximum force that is developed by the vibrator in pounds; W is the speed of the vibrator in radians per second; and t is the time in seconds.

The third vibrator 21 has been described above. A mathematical relationship to describe its mode of operation is rather complex and probably indeterminate and is not discussed herein.

The five modes of vibration to which the mold may be subjected in accordance with our invention are as follows.

First mode of vibration Vibrator 21 is disconnected from the upper platform 11 by means of the bolts 50 connecting the struts 22 to platform system 11. Platform systems 11 and 10 are connected together by the releasable rigid connections of bolts 18 and

nuts

19 and 19a. Vibrator 25 is placed in operation (but not vibrators 20) and through linkage 26 causes both platforms 10 and 11 to vibrate sinusoidally according to relationship (1) above. The amplitude a or the speed W can be changed by changing the eccentric cam of vi brator 25 or the speed of its motor. The vibration of the whole assembly depends upon the rocking action of pinions 42. Since both platforms 10 or 11 are connected there is no relatively motion between the posts 14 and the plate assembly 11.

Second mode of vibration Bolts 18 and nuts 1% are disconnected. Vibrators 20 are not operated and vibrator 25 is operated. Springs 13 thus serve to provide resilient support between the platforms. The relationship of instantaneous displacement of this mode of vibration, without considering transient effects, may be represented by the following expression:

Ka sin W t KM(W (3) Where X is the instantaneous amplitude of the displacement of platform 11 and, thus mold 12; K is the effective spring constant of the four springs 13 in pounds per inch. Aside from K, the numerator will be recognized as Formula 1 discussed above. W is a function of the speed of vibrator 25 as discussed in regard to Formula 1. M is the total mass (in slugs) of the platform assembly 11 and mold 12 supported by the four springs 13. According to this mode of vibration, selection of the spring constant K, platform mass M and speed W, is such that a vibration near the mechanical resonant frequency of the system is the preferred vibration frequency. During casting, the amplitude of vibration can be increased or decreased by slight changes in the frequency as by adjustment of the vibrator motor speed. It is to be noted that this mode of operation also has a self-regulating feature. If a casting tends to hang up or stick in the die, as often occurs, in spite of the utmost precautions, the effective mass M on the upper platform 11 will increase as a result of the drag. The springs 13 will then tend to deflect more and follow the casting movement and simultaneously react to sustain a greater load. Thus, when the casting sticks the system automatically compensates for the sticking by moving with the casting and simultaneously exerting a higher pull to free the casting thereby the sticking is overcome, without breakage as would result from the extremely high forces at a sudden stoppage.

Third mode of vibration In this mode of vibration the rigid connection (bolts 18 and

nuts

19 and 19a) between the platforms are disconnected and the vibrator 21 is disconnected. In this mode, platform 11 is oscillated by its vibrator 25 and the high speed vibrator 20 for the upper platform 11 is placed in operation. Simultaneously, under this set of dual vibration operation, a superimposed sinusoidal motion is effected according to the following relationship:

F sin W t Ka sin W t KM(W2) KM(W where the terms are as defined above with the additional factor, W being the speed of the vibrator 20 in radians per second. It will be appreciated that by altering the speed W of vibrator 25 or the speed W of vibrator 25, the amplitude X and the vibration speed of the upper platform 11 may be altered. It is noted that the instantaneous displacement, X of the upper platform 11 is comprised of two vibration components, wherein a high frequency vibration is, in effect, superimposed on the lower frequency mode of vibration.

Fourth mode of vibration The connections for this mode of vibration are the same as that for the third mode, except that the vibrator for the lower platform 25 is not in operation. Accordingly, with only vibrator 20 operating, a high frequency vibration is effected whereby a sinusoidal vertical reciprocating motion is imparted to platform 11. This effect through the spring action causes an instantaneous dislacement of the mold 12 according to the relationship:

where X, is the instantaneous displacement of the lefthand component of Equation 4 above. It will be appreciated that an adjustment or a change in the vibration frequency of vibrator 20 effects a change in the frequency parameter W which, in turn, causes a change in amplitude as well as frequency of the vibration.

Fifth mode of vibration The rigid connections (bolts 18 and

nuts

19 and 19a) between platforms 11 and are removed and vibrator 21 is connected to the upper platform 11 by means of the strut connections 22. Platform 11 is sufiiciently raised along posts 14, by raising struts 22 so that springs 13 are not contacted during the maximum displacement effected by vibrator 21. Adjustments of limit switches 23, adjustable trips 24 and the speed ratio varies the length of the stroke, the ratio of the upward to downward speed of vibration, and the absolute downward speed, as desired, according to the type of molding or casting that is to be produced.

Either the first mode of vibration, where vibrator 25 is used, or the fifth mode of vibration, where vibrator 21 is used, may be modified by also using vibrators 20. The use of vibrators 21 in that manner or in the third or fourth modes of vibration will give a finer grain structure to castings produced in connection with that use.

We claim:

1. Apparatus for the continuous casting of metals comprising an open-ended mold, a first platform carrying said mold, a second platform attached to said first platform by a releasable rigid connection, a vibrating means for vibrating said second platform at a selected amplitude and frequency, and spring means for connecting said first and second platforms and for vibrating said first platform at a different amplitude than said second platform when said rigid connection is released.

2. The apparatus as defined in claim 1 and also including a second vibrating means attached to the first platform for vibrating said first platform at a selected amplitude and frequency.

3. The apparatus as defined in claim 1 and also including a second vibrating means releasably connected to the first platform.

4. The apparatus as defined in claim 2 and also including a third vibrating means releasably connected to the first platform.

5. The apparatus of claim 1 wherein said vibrating means is adapted to vibrate said second platform in a substantially vertical direction at a frequency in the range of about cycles per minute to about 2000 cycles per minute and with an amplitude in the range of about 0.006 of an inch to about 0.250 of an inch.

6. The apparatus of claim 2 wherein said second vibrating means is adapted to generate generally vertical vibrations at a frequency in the range of about 2000 to about 6000 cycles per second.

7. The apparatus of claim 3 wherein said second vibrating means is adapted to generate generally vertical vibrations having a frequency of about 100 cycles per minute, a stroke in the range of about 4 inch to about 3 inches and a downward speed slower than their upward speed.

References Cited UNITED STATES PATENTS 3,075,264 1/1963 Wognum 164-83 2,760,243 8/1956 Kerb l64-83 XR 475,848 5/1892 Critcher 259-91 2,353,492 7/1944 OConner 164260 XR 2,763,040 9/1956 Korb 16483 XR 2,815,551 12/1957 Hessenberg et a1. 16483 2,775,008 12/1956 Easton et al. 164260 3,118,195 1/1964 Gouzou et a1. 16483 3,211,432 10/1965 Van Rossen 259--91 3,307,230 3/1967 Goss 164282 XR FOREIGN PATENTS 901,235 1/1954 Germany.

I. SPENCER OVERHOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner.