US1448480A - Apparatus for operating furnace doors - Google Patents

Description

Mar. 13, 1923. 1,448,480

- L. D. BEDELL APFARATUS FOR OPERATING FURNACE DOORS.

2 sheets-sheet 1 Filed. 001). 20, 1921 Mar. 13, 1923. 1,448,480

L. D. BEDELL APPARATUS FOR OPERATING FURNACE DOORS Filed Oct. 20, 1921 2 sheets-sheet 2 .9 I-Z- g' 7" 45 15 o 2/ I 20 'l /a II Patented Mar. 113, 11923.

- uni-"ran stares LESTER D. BEDELL, OF BETHLEHEM, PENNSYLVANIA.

APPARATUS FOR OPERATING FURNACE DOORS.

Application filed October 20, 1921. Serial No.v 509,145.

To all whom it may concern Be it known that I, Lns'rnn D. BED'E L, a citizen of the United States, residing at Bethlehem, in the county of Northampton and State of Pennsylvania, certain new and useful Improvements in Apparatusfor Operating Furnace Doors, of which the following is a specification.

This invention relates to ailapparatus for raising and lowering furnace doors and is particularly applicable to theftype of doors used on open hearth furnacesbut some of its features are applicsble to other uses.

It is well known that the door of an open hearth furnace usually rests on a supporting ledge in front of thedoor opening when in closed position, and is lifted vertically to open position, and that when the furnace isin use frequent opening and closing move- .ments of the door are necessary. Owing to the weight and structure of the parts, special precautions and great care are necessary in operating thedoor to prevent such jars and extra strains on the brick work of the .furnace or the parts of the door as to causeinjurious results. such as breakage or displacement. The water pipe connection for circulating water th'rou h the door for cooling and to prevent over eatin is one thing which particularly makes special care necessary. I

The purpose of the present invention is to cause the proper movement of-the door without shocks, jars or undue strains during the movement, or in bringing it to rest at either end of the movement, by means'which requires no specialcare or attention after being set in operation but which will act with certainty and automatically. It further in 4 cludes a reduction of the weight of the counterbalance materially below the weight' of the door. To accomplish these purposes the invention embodies a hoisting mechanism which is so constructed that when power is applied it will raise or lower the door at such moderate speed as to cause no jars or undue strains in starting and stopping or during the movement, and will automatlcally allow the door to come tov rest when it reaches its fully open or fully closed position, and by or through which the door when partly or fully open is counterbalanced by a weight weight of the door. The novel features will be more fully understood from the following have invented materially less than the? description and claims taken with the accompanying drawings. In the drawings:

Figure 1 is a cross'section through an :open hearth furnace, showing. the apparatus in elevation, the door being in its closed position.

Figure 2 is a view similar to Figure 1, except that the door is in its opened position.

Figure 3 is a diagrammatic front view showing the arrangement of the chain around the various pulleys.

Figure 4 is a front view of the door showing the water-cooling pipes; and v 4 Figure 5 shows a detail view in elevation of the upper pulley-block.

In the drawings the invention is shown applied to an open hearth furnace 10 having the door opening 11 and the supporting ledge 12 on which the door 13 comes to rest when in closed position. The door 13 is adapted to move vertically from the posi tion shown in Figure 1 up along the face of the furnace wall to the open position shown in Figure 2. A V-s'haped lifting bar-14 (see Figure 4) is pivoted at its ends to the top of the door, and it will be understood by those skilled in the art that suitableguides (not shown) may be provided for the door. A lifting member 15 is secured at one end to the door through the ll-shaped bar with a flexible portion 16, preferably in the form of a chain, passing upwardly therefrom over the roller 17 mounted above the top of the furnace and with a flexible portion 18, also preferably in the form of a chain, passing over roller 19 mounted above the rear portion of the furnace and having a downwardly extending end. Bearing brackets 20 and 21 may be secured to the furnace at its top to carry the rollers 17 and 19, and an adjustable guide and stop for the depending end of the flexible part 18 is supported from bracket 21 by a plate or extension 22. The stop consists of an externally screw threaded tube 23 passing through the plate-22 and held in vertically adjusted position by the nuts 24, 25, surrounding it and fitting the upper and lower surfaces of plate 22. The depending end of the flexible chain portion 18 passes down through the tube 23.

The means for causing and controlling the movements of the door through the lifting member 15 is connected to the depending end of the chain portion 18 immediately be ley low the guide stop 23 when the furnace door is closed. It embodies a pulley body or frame 26 secured to the end of chain 18 and having mounted therein a rotary member 27 having thereon two spaced smooth peripheral grooves or trackways 28'and 29 of different diameters, the groove 28 being of materially greater diameter than that of 29, as seen by reference to Figure 5. counterweight 30, preferably-embodying a number of separate removable discs to allow for adjustment, is'mounted materially below .the pulley body 26 to'move vertically and freely in a guide member 31, except when it strikes the fixed limiting stop bar 32 near the bottom. A pulley '33 having a single smooth circumferential groove or trackway is secured to the upper end of counterweight 30. Intermediate the pulley mechanism carried by the-aframe 26 and the pulley 33' of the counterhveight there is a rotary drive shaft 34 mou-n ed in fixed bearings 35 and driven in either direction through suitable gearing connection 36 from a suitable motor, but preferably an electric motor 37. The drive shaft 34 carries a pulley wheel 38 provided with a circumferential groove or trackway, the surface of which is smooth circumferentially and adapted to frictionally engage and drive a chain or flexible member engaging it under sufficient tension. An endless flexible cable, preferably in the form of a chain, 39, is so connected to the pulley mechanism of the lifting member 15, to that of the counterweight, and to the drive shaft, that it sustains the weight of the door and counterweight in operation'and serves as a differential connection enabling a counterweight of substantially one half the weightof the door to counterbalance it. This endless chain also serves by its movement in-operation to move the counterweight and the end of the lifting member in the same direction but at different speed, theacounterweight moving fast.

est. To accomplish this, one loop end of chain 39 passes around under the drive wheel pulley 38 with the sections leaving opposite sides passing up to the rotary member 27 of pulley 26, one going around it in groove 28 from one side, and the other going around it in groove 29 from the other side, and then down to and around the single groove pul- 33 of the counterweight. The length of that endless chain is such that when the door 13- is in closed position the counterweight is at the upper limit of its movement, and when the counter-weight descends and strikes its support 32, the door is in the proper open position.

It is believed that the actual operation of the apparatus will be more easily and clearly understood if the mechanical vmovements taking place because of the differential pulley connections and arrangement shown diagrammatically in Figure 3 are first explained. If power is applied to drive pulley 38 to turn it in the direction of the arrow, and there is sufficient tension on chain 39 to cause the necessary frictional engagement,

ithe chain will move longitudinally, going from pulley 38 up to and over the groove 28 of large diameter, then down to and around pulley 33 and back to the upper pulley, but this time over the groove 29 of materially less diameter than groove 28, and back to pulley 38. If there is no longitudinal slipping of the chain on the pulleys, it is clear that that part of the chain passing up from pulley 38 to and over groove 28 must move faster than that part leaving groove 29 and going back to drive pulley 38, because of the larger diameter of groove 28 than groove 29, and because the two move together and theperipheral speed is different. Naturally however, one part of the continuous chain under tension cannot move faster than another, and the result is a continual shortening of the loop extending down from grooves 28 and 29 down around pulley 38. Since pulley 38 is in fixed supports, the upper pulley frame carrying grooves 28 and 29 must move down towards pulley 38. In the same way, the part of the chain leaving groove 28 going down to pulley 33 moves faster than the part coming from pulley 33 to groove 29. The effect of this is to continuously produce slack in or elongate that loop which engages pulley 33 and supports the counterweight in addition to and equal to that elongation produced by the downward movement of the pulley mechanism carrying grooves 28 and 29. The counterweight thus moves in the same direction as but at twice the speed of the upper pulley. When the motor and drive shaft are reversed, the operations are the same only in the opposite direction The operation of the apparatus will now be explained. When the door is closed and the parts in the position shown in Figure 1, there isof course tension on cable 39 due to the suspended counterweight 30. and therefore the loop end around the drive pulley 38 has a very material frictional engagement or grip. If then the motor is started, rotating drive pulley 38 in the direction indicated by the arrow in Figure 3, the chain loop to grooves 28 and 29 will at once commence to shorten, drawing them and the end of the lifting member down and thus lifting the door 13, the movement being very gradual and steady and much less than the speed of the drive shaft. The'ratc of movement depends on the relative sizes of pulleys 28 and 29. As heretofore indicated, the supporting loop for the counterweight is elongated in double proportionso that it moves downward at twice the speed at which the doormoves upward. When the counterweight strikes the fixed support 32 and can move downward no further, any additional longitudinal movement of the endless chain would relieve by elongation that part hanging down as a loop under pulley 33 from all strain or tension due to the Weight of the counterweight, and the result would be that the door.- would ha at the momentn'othing to counterbalance it and nothing to support it save thefriction of the chain on drive pulley 38. That fric tion is not sufficient with the slightest slackness in the chain beyond the pulley or anywhere, and thus ithas been found that even when the drive shaft andpulley 38 continue to rotate after the counterweight comes to rest on its support, the door will automatically stop. its upward movement, and of course the pulley mechanism 26 its downsuch ward movement. The frictional engagement of the chain with the drive pulley 38 has been rendered ineffective to drive the chain. The pulley 38 turns in contact with the chain, but no longer drives it. The power should of course be cut off when the door reaches position to avoid wear, but the automatic stopping of the movement of the door prevents more serious damage due to the failure of the operator to do so. In closing the door, the operation of the motor is reversed and the drive shaft turns in the opposite direction, causing return movements of the parts which are similar but in the reverse direction. When the door rests on ledge 12 the pulley mechanism 26 ceases to move upward because such continued movement would tend to elongate its loop connection to the drive shaft relieving its tension or effective frictional engagement with the drive pulley.

One important feature of the invention is that the speed of movement of the drive -member is greatly reduced in its effective action in moving up or down either or both of the suspended movable parts or members -wards or from a pulley on a fixed drive shaft at a speed much less than that of the chain or drive pulley would have a similar differential moving action if any one of the pulleys in the differential system were made the fixed drive pulley and the othertwo used as movable supporting pulleys. and therefore as to this feature the invention is not limited to the use of a particular pulley as the drive pulley, beyond what is stated in as the door and counterweight, thus the claims. Another important feature of the invention, in a sense distinct from while -cooperat1ng with the differential means for making the movement of the door slow and steady, resides in the friction drive connecpoint avoids the necessity for such close watch and accurate work on the part of the operator. and also the danger of injury to the door or operating parts and connections.

While therefore one specific embodiment of the invention has been shown and described, it will be understood that in its broader aspects the invention is not limited to that form further than is particularly set forth in the claims.

. Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a device of the class described the combination with a vertically movable door. of a movable lifting member connected thereto, and means for counterbalancing said door and for moving it through connection with said lifting member comprising a counter-weight of materially less weight than the door, differential operating and supporting mechanism connecting the end of said member and counter-weight bringing about a substantial balance, and means in a fixed position for applying power to said operating and supporting means to cause movement of said door and counter-weight in either direction at different speeds.

2. In a device of the class described the combination with a vertically movable door. of a movable lifting member connected thereto, and means for counterbalancing said door and for moving it through connection with said lifting member comprising a counterweight of materiallyless weight than the door, differential operating and supporting mechanism connecting the end of said mem her and counterweight bringing about a substantial balance and means in a fixed position for applying power to said operating and supporting means to cause movement of said door and counterweight in either direction at different speeds, and automatic means for rendering the action of said power means ineffective on the operating means when the door reaches either its fully open or fully closed position.

3. In a device of the class described the combination with a vertically movable door. of a movable lifting member connected thereto, and means for counterbalancing said door and for moving it through connection with said lifting member comprising a counterweight of materially less weight than the door, differential operating and supporting mechanism connecting the end of said memcombination with a vertically movable door,

of a lifting member therefor having a flexibleportion with a downwardly extending end, a lifting pulley secured to said end the rotary part of which has two grooves of different diameters, a counterweight of substantially half the weight of said dopr, a stop to limit its downward movement, a pulley on the upper end of said counterweight, a

fixed drive shaft carrying a friction drive wheel or pulley, and an endless chain or cable passlng around and frictionally engaging said drive pulley with its two sections extending therefrom 'on opposite sides to the lifting pulley and passing over the rotary part in the separate grooves of different diameter and then down and around 1the single groove of the counterweight pul- 5. In a device of the class described the combination with a vertically movable door, of a lifting member therefor having a flexible portion Witha downwardly extending end, a counterweight of materially less weight than the door below said end, astop for limiting its downward movement, pulleys on said end and counterweight one of which has a rotary member. provided with tWo peripheral grooves or trackways of different diameters, a drive shaft held to rotate in a fixed position intermediate said end and counterweight having thereon a pulley or circularly grooved frictional driving part and an endless chain or cable with one end of its loop formation passing around said drive pulley or part and frictionally engaging it with its two sections extending therefrom on opposite sides to and around the two grooves or trackways of different diameter in the said pulley carrying them and then to and around the other of said first mentioned pulleys whereby said endless chain and fixed drive shaft will form a supporting connection for said door and counterweight and a differential frictional drive means for moving them between the fixed limits of their movement.

, 6. In a device of the class described the combination with a vertically movable door with a fixed support when closed of a lift- .elongate its operative movable member to move said member and counterweight up ing member therefor having a flexible por: tion with a downwardly extending end, a counterweight of materially less weight than the door, a fixed stop for interrupting the downward movement of the counterweight when the door reaches open position, a fixed rotary drive member intermediate said end and counterweight, flexible differential means so connecting said downwardly extending end, counterweight and drive member as to substantially balance said door and counterweight and so frictionally engaging said drive member through the weight of said door and counterweight, when both are elevated above their supports, that when said drive member is operated said downwardly extending end and counterweight will be moved by said flexible means in the same direction, the counterweight moving at a' materially greater speed than said end, but when either reaches its bottom support the frictional engagement of the drive memher will automatically be so reduced that it will impart no further movement in that direction.

7. In .a device of the class described, the combination with a vertically movable member having a fixed support at its lower position, a vertically movable counterweight having a support in its lower position, means connecting said member and counterweight to sustain the one which is above its support, drive means frictionally connected to move sald member and counterweight up or down and automatic means for causing the frictional drive connection to slip and become inoperative to cause further movement when the member or counterweight reaches and rests on its support. a

8. In a device of the class described, the combination with a vertically movable mem-- ber having a fixed support at its lower position, a vertically movable counterweight having a support in its lower positlon, meansconnecting said member and counterweight to sustain the one which is above its support including a flexible chain or cable and pulleys engaged thereby and drive meansin a fixed posltion engaged by a loop of said chain to sustain and\ frictionally drive said chain under the tension produced by the weight of said movable member and counterweight to gradually shorten or connection to said or down, and automatic means for causing the frictional drive connec'tion to slip and become inoperative to cause further movement when the member or counterweight reaches and rests on ts support.

9. In a combination with a vertically movable member having a fixed support at its lower position, a vertically movable counterdevice of the class described, the

weight having a support in its lower posi tion, means connecting said member and counterweight to sustain the one which is above the support including an endless flexible chain or cable and differential ulley mechanism engaged thereby and inc uding frictional engagement therewith, reversible drive means including a rotary shaft in fixed bearings carrying a pulley or drive which is frictionally engaged by a loop of said chain or cable under tension to drive it longitudinally and thereby through the differential pulley connection shorten or elongate its effective connection to the movable member moving it up or down at a speed materially less than that of the drive member or chain and the frictional engagement of said chain being such that it will automatically become ineffective or inoperative through slipping to cause further movement of said movable member through the further movement of said drive means when the movable member or counterweight reaches and rests on its support. 1

10. In a device of the class described, the combination with a vertically movable member having a fixed support at its lower position, a vertically movable counterweight having a support in its lower position, means connecting said .member and counterweight to sustain the one which is above its support including an endless chain or cable and difi'erential pulley mechanism having loop connection therewith, one pulley housing or frame being connected to said movable member to sustain and move it and another pulley housingbeing connected to said counterweight, reversible driving means including a rotary shaft in fixed bearings and carrying a rotary member which is frictionally engaged by a loop of said chain or cable under the tension due to the weight of said movable member and counterweight and the frictional engagement being such that the rotation of the drive member will cause gradual movement of said movable member and counterweight towards or away from their supports but will be rendered inoperative for further movement in the direction of movement when either rests on its support.

11. In a device of the class described, the combination with a vertically movable member having a fixed support at its lower position, a vertically movable counterweight having a support in its lower position, means connecting said member and counterweight to sustain the one which is above its support including an endless chain or cable and differential pulley mechanism having loop connection therewith, one pulley housing or frame being connected to said movable member to sustain and move it, and another pulley housing being connected to said counterweight, reversible driving means includinga rotary shaft in fixed bearings and carrying a rotary memher which is frictionally engaged by a loop of said chain or cable under the tension due to the weight of said movable member and counterweight and the frictional engagement and the differential arrangement of the engaging surfaces of the pulleys being such that the rotation of the drive member will longitudinally move the chain, shortening the loop connection between it and one pulley while elongating the loop connection to the other pulley at rates of speed materially below that of the drive means and chain and will thus gradually and simultaneously move the movable member and counterweight, one, from its support and the other towards its support, un-

til one or the other reaches its support, when the frictional moving means will become inoperative and the movement of the movable member and counterweight will automatically cease.-

12. In a device of the class described, the combination with a vertically 'movable member and a counterweight therefor of three separate frames having therein shafts carrying rotary parts or pulley wheels adapted to receive and frictionally engage a chain or cable passing over them, one of said shafts having two peripheral chain receiving surfaces of different diameters connected to rotate together, an endless chain or cable so bent as to form two loops fitting at theirends in the twochain receiving surfaces of d1fferent dliameter, one section of the chain or cable leaving the surface of larger diameter passingin loop form around a pulley in one of the other frames and back to the surface of smaller diameter, and the section of chain or cable leaving the surface of smaller diameter passing in loop form around the pulley in the third frame and back to the surface of larger diameter, means for rigidly supporting and rotating one of said rotary parts or pulley wheels, means for connecting the other pulley frames respectively to support said vertically movable member and counterweight, thus putting tension on the chain and causing its frictional engagement with the fixed driven rotating member or pulley to be sufficient for driving.

. 13. In a device of the class described, the

the other having a single groove or chain engaging part, means connecting one of said pulleys to said door and the other to the counterweight, a drive pulley or wheel mounted to rotate in fixed position and having a groove or part for receiving and frictionally engaging a chain loop, means-for drivin said drivepulle'y in either direction, an end ess chain or cable having two looped ends fitting: in the two grooves or parts of different diameter with that portion of the chain leaving the larger groove passing to and around the rotary member in the other movable pulley and back to the groove of less diameter, and that portion of the chain leaving the groove o'f-smaller diameter passing to and around and frictionally engaging the drive pulley and then back tothe groove of eater diameter.

14:. In a device of the class described, the combination with a vertically movable member having a fixed support at its lower position, a vertically movable counterweight having a support in its lower position, means connecting said member and counterweight to sustain the one which is above its support including a flexible'chain or cable and pulleys engaged thereby and drive means in a fixed position engaged ;by a loop of said chain to sustain and frictionally drive said chain under the tension produced bythe weight of said movable member and counincluding a rotary terweight togradually shorten or elongate its operative connection to said movable mei'nber to move said member and counterweight up or down.

15. In a'device of the class described, the combination with a vertically movable member having a fixed support at its lower, position, a vertically movable counterweight haying a support in its lower position, means connecting said member and counterweight to sustain the one which is above the sup- 1 port including an endless flexible; chain or mechanism enfrictional encable and differential pulley gaged thereby and including gagement therewith, reversible drive means shaft in fixed bearings carrying a pulley or drive which is frictionally engaged by a loop of said chain or cable under tension to drive it longitudinally and thereby through the differential pulley connection shorten or elongate its effective connection to the movable member moving it up or down at a speed materially less than that of the drive member or chain.

In testimony whereof I hereunto affix my signature.

J LESTER "15'. BEDELL.

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