US2600441A - Method of manual door operation of vertically movable doors - Google Patents

Description

June 17, 1 R. H. SOMMERS ET AL 2,600,441

METHOD OF MANUAL DOOR OPERATION OF VERTICALLY MOVABLE DOORS Filed Oct. 29, 194? 3 Sheets-Sheet 1 r E O (D E 0 JNVENTORS R0552 H. SUM/V5196 BY ARTHUR 14 F/SA/V/f June 17, 1952 R. H. SOMMERS ET AL METHOD OF MANUAL DOOR OPERATION OF VERTICALLY MOVABLE DOORS Filed Oct. 29, 1947 5 Sheets-Sheet 2 mmvrow ROBf/Pf so/ww/es y ART/90A W. FHA NA A TTOR/VEY Patented June 17, 1952 METHOD OF MANUAL DOOR OPERATION OF VERTICALLY MOVABLE DOORS Robert H. Summers, Waukesha, and Arthur W. Frank, Wauwatosa, Wis., assignors to Hevi Duty Electric Company, Milwaukee, Wis, a corporation of Wisconsin Application October 29, 1947, Serial No. 782,818

Claims.

1 Our invention relates broadly to heat treating apparatus and more particularly to an improved method and structure of door closure mechanism for heat treatment apparatus.

One of the objects of our invention is to provide an arrangement of closure mechanism for heat treatment apparatus in which the full weight of the door of the closure mechanism may be used to effect closure of the opening of the heat treatment apparatus.

Another object of our invention is to provide a door closure mechanism for heat treatment apparatus in which the mass of the door is effective against cam-like or inclined door jamb members arranged to force the door into sealed relation to the opening in the heat treatment apparatus under control of door lifting and lowering mechanism.

Still another object of our invention is to provide a construction of reversible pawl mechanism for controlling the position of the associated door mechanism under manual control.

A further object of our invention is to provide a construction of gravitationally actuated pawl and sprocket mechanism for selectively positioning a counterweighted door closure of a heat treatment chamber.

Other and further objects of our invention reside with novel arrangement of closure mechanism for heat treatment apparatus as set forth more fully in the specification hereinafter following by reference to the accompanying drawings in which Fig. 1 is a front view of a heat treatment apparatus equipped with a door operating mechanism of our invention; Fig. 2 is a side elevational view of a heat treatment apparatus showing the door operating mechanism of our invention associated therewith; Fig. 3 is a fragmentary end elevational view of the door control mechanism employed in the system of our invention illustrating the reversible pawl in position for lowering the heat treatment appa ratus door; Fig. 4 is a view similar to the view shown in Fig. 3 but illustrating the position of the reversible pawl for raising the heat treatment apparatus door; Fig. 5 is an enlarged fragmentary front elevational view of the door control mechanism illustrated in Figs. 3 and 4 but showing a portion of the sprocket wheel broken away and illustrated in section; Fig. 6 is a fragmentary vertical sectional view through the door control mechanism with the pawl and certain of the associated parts shown in elevation; Fig. '7 is an elevational view of the reversible pawl; Fig. 8 is a horizontal sectional view taken substantially on line 3-5 of Fig. '7 Fig. 9 is an end view of the pawl shown in Figs. 7 and 8; Fig. 10 is a vertical sectional view taken substantially on line lt-lfi of Fig. 7; Fig. 11 is a horizontal sectional view taken through the gravitationally weighted shiftable arm associated with the pawl. meohanism, the View being taken substantially on line ll-l l of Fig. 12; and Fig. 12 is an elevational view of the gravitationally weighted shiftable arm shown in Fig. 11.

In heat treating operations where the operator is' required to raise or lower a furnace door manually, several disadvantages exist in mechanism heretofore available. Chief among these disadvantages has been the fact that the door, being counterbalanced, and not having a means of relieving the counterweight, did not remain closed as tightly as desired so as to exclude undesirable atmosphere or retain atmosphere used within the heating chamber. This can be readily understood as doors often weigh two. or three hundred pounds and must be counterweighted so that they will operate freely with very little manual effort. Vibration within a building or carelessness in adjusting the mechanism'or in operation tends to allow the door to creep open a trifle, thus causing the door'to leak at its juncture with the furnace opening.

Makeshift methods are often employed to correct this condition such as placing additional weights on the furnace door and wedging or clamping it against the furnace chamber opening. These various methods all add to difficulties in operation requiring extra labor.

The importance of maintaining the proper type and amount of atmosphere in a furnace chamber can best be illustrated by the fact that it is often necessary to spend as much or more on equipment to produce atmosphere than it does for the furnace itself, thus, to waste it through a leaky door is inefiicient and expensive.

Another effect of a leak at the chamber opening is that the draft of air entering the furnace not only contaminates the atmosphere, but produces Variations in temperature which are detrimental to furnace operations.

Another disadvantage has been that the operator was required to use both hands to perform the operation of raising or lowering the door because of the necessity of having to engage or disengage a pawl or other device from the chain sprocket while holding the door raising cranl: at the same time. This did not allow the operator to work efficiently and required that he lay down his tongs or other tool so as to free both hands before he could open or close the door. In operations requiring the insertion and removal of work from the furnace in rapid succession, such as in the treatment of high-speed steels, delay is quite objectionable as it hinders the operator at a time when he should be handling material with the utmost speed.

Our invention is directed to mechanism that is incorporated into the door lift equipment which provides a simple means forthe operator to lift the weight of the counterweight in such manner that the full weight of the door in the door jamb is used to effect an improved seal between the door and the furnace chamber. Likewise this same mechanism enables a furnace operator to raise or lower the door and then hold it at any desired height through the use of the mechanism described thus leaving both hands free to handle tongs or other equipment to insert or remove work from the furnace. This latter advantage is especially useful in the heat treatment of high speed steels where speed in operation is essential to inserting or removing work from the furnace in order that a minimum amount of contamination of the atmosphere within the furnace will result and that the steel can be handled between operations in as short a time as possible to prevent surface deterioration.

Other advantages are apparent; the mechanism can be set to perform the desired function of holding the door at the proper level, or to assist in lifting the counterweights, in advance of the time the operator is required to perform the operation. Thus if it is necessary to hold the door open at a certain height, the operator will set the mechanism in position while the door or cover is closed and at a later time be free to raise the door and hold it at the desired level without having to operate a mechanism other than the door operating crank.

One preferred way of accomplishing the object of this invention will be understood by detailed reference to the accompanying drawings in which the door I is shown in closed position against furnace 2 and resting on lugs, either solid or roller type, 3 in the inclined door jambs 4. Chains 5 extend upward from the door I over sprockets 6 and down to counterweights I. Sprocket B is attached to a. shaft 8 on which is also mounted a sprocket 9 driven by an endless chain which, in turn, passes around sprocket II which can be turned by operating crank l2 attached to shaft 14 on which operating crank I2 is secured.

We provide in addition to the mechanism described a special pawl l which incorporates two projections [5a and [5b to engage the sprocket ll welded to a horizontal bar I50 which is pivoted at a point l6 equidistance from each end, thus allowing the pawl Hi to be raised or lowered at either end. Adjacent to this pawl l5 and mounted on the same pivot I6 is a weight I! carried by an arm l8 which extends upwards and over the pawl l5 and can be moved from side to side so as to shift the weight to either side of the pawl l5 to engage either of the proiections l5a; or 15b in the sprocket H as desired by the operator. As either projection Pia or l5b engages the sprocket II at some distance past the center line it will be understood that the pawl prevents the sprocket II from being reversed, and allows it to travel freely in one direction until stopped by the operator or other mechanical limitations. The arm I8 is apertured at 18a and registers with aperture We both of which are aligned and which fit over the pivot l6. Pivot I6 is in the form of a stud bolt secured to bracket l9 fastened to the structural support 20 of furnace 2. In actual use the operator of the equipment would follow the procedure outlined hereinafter:

To raise the door I the weight I! would be moved to the position shown in Fig. 4 where arm I 8 has moved weight into a position rocking bar I50 in a counterclockwise direction, which would cause the pawl l5 to rotate to disengage projection l5b from the sprocket ll upon release by the operator. The operator would then depress handle I2 slightly, allowing the pawl IE to release and the weight I! to shift the projection l5a of pawl l5 into engagement with sprocket II in a position for raising the door I. The door I can then be raised by the process of turning the crank 12 until the desired height is reached. At this point, a slight reversal of the sprocket H would engage the projection [5a of pawl l5 and lock the door at the desired height. Then the operator would move arm I8 in a clockwise direction as shown in Fig. 3 which moves the weight I! in the opposite direction, abutting weight ll against bar I5c in a direction to shift projection 151) into engagement with sprocket H in the position shown in Fig. 3 where the mechanism is ready to close the door I.

In closing the door I, the operator would again slightly reverse the sprocket l l releasing the projection I5b of pawl 15 which would disengage due to the fact that the weight 11 had been shifted, and would lower the door I to a closed position.

In order that the operator may more effectively seal the door by taking the load of the counterweight '1 off it, he would continue to turn the crank l2 until the chains 5 supporting the door I showed evidence of slack. This extra slight turn would usually mean that the pawl [5 would engage the sprocket one or two teeth past where it would have stopped if no additional pressure had been exerted. By using the full weight of the door I, the inclined jambs 4 would more effectively force the door I against the front of the furnace 2, thus creating a better seal, the advantages of which were indicated hereinbefore.

The reversible pawl mechanism 15 provides for the unidirectional control of the lifting or lowering mechanism and insures the stopping of the door selectively at the desired position. Reversal of the pawl mechanism I5 is performed very simply and quickly by angular displacement of the arm H3 in the desired direction as explained in connection with Figs. 3 and 4. The sealing of the door with respect to the opening of the heat treatment apparatus is made very effective by the forcing of the door into sealing relation with the sides of the opening in the heat treatment apparatus by the coaction of the lugs 3 extending in opposite directions from the door into the inclined guideways formed by the door jambs A. The fact that the inclines in the door jambs are directed toward the opening in the heat treatment apparatus insure the movement of the door toward the opening in the heat treatment apparatu for establishing sealing relation therewith.

While we have described our invention in one of its preferred embodiments we realize that modifications and changes may be made in the mechanism we have illustrated and we desire that it be understood that no limitations upon our invention are intended other than may be imposed by the scope of the appended claims.

What we claim and desire to secure by Letters Patent of the United States is as follows:

1. Door operating mechanism including a vertically movable door, vertically arranged guideways for controlling the movement of said door in a vertical direction, counterweighted means for balancing the vertical movement of said door and control means for moving said door to a selected position, said control means including a reversible crank,a chain and sprocket mechanism operated by said reversible crank with said chain operatively associated with said counterweighted means, a reversible pawl pivotally mounted adjacent said sprocket mechanism, substantially coplanar with said chain mechanism.

and having a pair of angularly directed teeth members having overall dimensional limits of less than the distance between the paths of travel of said chain mechanism and operative to engage the sprocket teeth of said sprocket mechanism at a position remote from the center thereof and a weighted lever pivotally mounted on the same center with said pawl and operative to be shifted to either of two limiting positions engaging said paWl for gravitationally maintaining one of the teeth members of said pawl in toothby-tooth engagement with the sprocket teeth of said sprocket mechanism for unidirectionally controlling the movement of the door to a selected position.

2. Door operating mechanism including a vertically movable door, vertically arranged guideways for controlling the movement of said door in a vertical direction, counterweighted means for balancing the vertical movement of said door, and control means for moving said door to a selected position, said control means including a reversible crank, a chain and sprocket mechanism with said chain operatively associated with said counterweighted means, a reversible pawl pivotally mounted adjacent said sprocket mechanism comprising a plate member having a pair .of normally projecting spaced diverging teeth thereon directed toward and alternately engageable with the teeth of said sprocket mechanism and operative in a plane substantially coplanar with a plane through said chain mechanism, and means angularly shiftable about the pivotal center of said reversible pawl for gravitationally maintaining one of the teeth of said pawl in tooth-by-tooth engagement with the sprocket teeth of said sprocket mechanism for unidirectionally controlling the movement of the door to a selected position.

3. Door operating mechanism including a vertically movable door, vertically arranged guideways for controlling the movement of said door in a vertical direction, counterweighted means for balancing the vertical movement of said door, and control means for moving said door to a selected position, said control means including a chain and sprocket mechanism with said chain operatively associated with said counterweighted means, a reversible pawl pivotally mounted adjacent said sprocket mechanism comprising a plate member having a pair of normally projecting spaced diverging teeth thereon directed toward and alternately engageable with the teeth of said sprocket mechanism, a lever arm concentrically mounted with respect to the pivotal mounting of said pawl and a weight carried by the end of said lever arm, said weight being angularly shiftable into selective engagement with the rear of each of the teeth on said plate member in either of the limits of angular movement thereof for gravitationally maintaining one of the teeth of said pawl in tooth-bytooth engagement with the sprocket teeth of said sprocket mechanism for unidirectionally controlling the movement of the door to a selected position.

4. Door operating mechanism including a vertically movable door, vertically arranged guideways for controlling the movement of said door in a vertical direction, counterweighted means for balancing the vertical movement of said door and control means for moving said door to a selected position, said control means including a chain and sprocket mechanism with said chain operatively associated with said counterweighted means, a reversible pawl pivotally mounted adjacent said sprocket mechanism comprising a plate member having a pair of normally projecting spaced diverging teeth thereon directed toward and alternately engageable with the teeth of said sprocket mechanism, said plate member and said teeth having a total overall linear dimension that is less than the direction between the paths of travel of said chain mechanism, and a lever arm pivoted adjacent said sprocket mechanism and having a weighted mass projecting substantially normal thereto and over said plate member for engaging said plate member in either of the limiting positions thereof substantially within the limits of the linear dimension of said plate member for gravitationally maintaining one of the teeth of said pawl in tooth-by-tooth engagement with the sprocket teeth of said sprocket mechanism for unidirectionally controlling the movement of the door to a selected position.

5. Apparatus for controlling the vertical movement of a balanced door comprising a chain and sprocket, a reversible crank connected with said sprocket, said chain extending around said sprocket in substantially parallel paths, a pivotally mounted bar located between the paths of travel of the chain, said bar carrying a tooth at each end thereof disposed in a plane substantially normal to the plane of said bar, each tooth being alternately engageable, at the limits of movement of the bar, with the teeth of said sprocket, a lever arm concentrically mounted with respect to the pivotal mounting of said bar, and a weight carried by the end of said lever arm and projecting over said bar and selectively engageable therewith adjacent opposite ends of the bar for maintaining one or the other of the teeth in engagement with said sprocket for latching the sprocket and the chain engaged therewith in a selected position subject to release by a reverse movement of said crank, said bar and the teeth thereon and said lever arm all being disposed between the paths of travel oftthe chain and substantially coplanar therewi h.

ROBERT I-I. SOMMERS. ARTHUR W. FRANK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 189,317 McCune Apr. 10, 1877 257,306 Farley May 2, 1882 321,284 Dorman June 30, 1885 1,032,004 Hillman July 9, 1912 1,126,080 Quigley Jan. 26, 1915 1,296,892 Wilputte Mar. 11, 1919 1,752,806 Otis Apr. 1, 1930 2,008,000 Brunst et al July 16, 1935 2,029,818 Fleming Feb. 4, 1936 2,494,604 Zimmer Jan. 17, 1950 FOREIGN PATENTS Number Country Date 322,300 Italy Nov. 6, 1934

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