US 3700122 A
A pusher-type furnace for the heating of metal ingots, blooms, billets or bars to rolling temperature, is provided at its inlet side with a billet-receiving platform or table upon which a pusher assembles one or more billets for advance into the furnace by a main pusher, the latter serving simultaneously to displace the entire array of workpieces and advance one or more of the latter out of the furnace.
Description (OCR text may contain errors)
United States Patent Sevenich et al.
PUSHER-TYPE FURNACE Inventors: Theodor Josef Sevenich, Dortmund;
Wolfgang Fabian, Dortmund-Hombruch; Klaus Kuhn, Dortmund, all
of Germany Assignee: Maschinenund Werkzeugbau GmbH, Dortmund-Hombruch, Germany Filed: Oct. 1, 1970 Appl. No.: 77,095
Foreign Application Priority Data Oct. 2, 1969 Germany ..P 19 49 747.3
US. Cl ..214/24, 198/221, 263/6 R Int. Cl ..F27b 9/22 Field of Search ..2l4/23-25;
263/6 B; l98/22l  References Cited UNITED STATES PATENTS 3,490,621 1/1970 Cook ..214/23 FOREIGN PATENTS OR APPLICATIONS 639,848 12/1936 Germany l4/24 1,205,574 11/1965 Germany .Q .;214/23 Primary Examiner-Robert G. Sheridan Attorney--Karl F. Ross I ABSTRACT A pusher-type furnace for the heating of metal ingots, blooms, billets or bars to rolling temperature, is provided at its inlet side with a billet-receiving platform or table upon which a pusher assembles one or more billets for advance into the furnace by a main pusher, the latter serving simultaneously to displace the entire array of workpieces and advance one or more of the latter out of the furnace.
4 Claims, 1 1 Drawing Figures PATENTEU 24 I97? 3.700.122
w 64, 6 6c 68 60! v 6 7 I Theodor J Sevenich 7" Wolfgang Fabian E J 1 Klaus KUhn 3 L. INVENTORS.
3 BY 65w 00 Attorney PUSHER-TYPE FURNACE FIELD OF THE INVENTION paratus and, more particularly, to improvements relating to pushertype furnaces and installations incorporating same. More particularly, the invention relates to an improved feed arrangement for a pusher-type furnace and to a method of operating same.
BACKGROUND OF THE INVENTION A pusher-type furnace generally comprises an elongated furnace chamber provided with means, e. g. a pair of rails for carrying billets, bars, blocks, blooms, ingots and like workpieces through a space which is heated by combustion or by regenerative-heated gases, for heattreatment of the workpieces and especially, the heating thereof to rolling temperature. In the furnace, hot gases contact the workpiece both from above and from below and the relatively hot workpiece discharged from the furnace may be directly subjected to rolling or other metal deformation.
Furnaces of this type are disclosed in US. Pat. Nos. 3,245,672 and 3,296,039. r
In general, a pusher-type furnace is provided at the charging or inlet end of the furnace with a ram of like pusher member designed to advance a fresh workpiece into the furnace through a door or window thereof, to simultaneously displace all of the workpieces within the furnace through an increment equal to the width of the introduced workpiece, and to shift a workpiece at the discharge end of the furnace out of the outlet door. The workpieces within the furnace lie in laterally contiguous (abutting) relationship and the furnaces operate more or less periodically with the period determined by the length of the furnace, the number of workpieces to be accommodated therein, the width 'of the workpiece and the residence time of the workpiece within the furnace that is considered desirable.
Such furnaces may be provided with supply means, e.g. a roller conveyor upon which the workpieces are delivered to the charging apparatus and with discharge means, e.g. a roller conveyor, upon which the emerging workpieces are carried to a further processing station, e.g. a rolling mill. The most convenient method of operating the furnace makes use of a furnace chamber or path having a width which is greater than the maximum length of the billet or other workpiece to be treated and inserts the workpieces laterally, the workpieces arriving in the longitudinal direction upon the roller conveyor and being shifted transversely to this direction into the furnace. The workpieces are then advanced periodically or in increments through the furnace in a direction transverse to their length.
Numerous installations established in recent years have made use of a number of such pusher-type furnaces arranged in parallel relation between the supply conveyor and the discharge conveyor. One of the primary problems encountered with such systems is the fact that efficient use of the conveyor arrangements requires the periods of the pusher-type furnaces to be established with respect to one another such that the discharged workpieces do not encounter one another. This is accomplished by operating all of the charging arrangements simultaneously, thereby ensuring that a workpiece will be discharged from each of the pushertype furnaces at each stroke. Hence each furnace must be operated at the charging rate determined by the slowest furnace. More complex synchronization of the charging means have proved to be unsuccessful.
OBJECTS OF THE INVENTION It is, therefore, the principal object of the present invention to provide a pusher-type furnace installation wherein the aforementioned disadvantages can be obviated.
Another object of the invention is the provision of an improved method of operating a pusher-type furnace and especially a pusher-type furnace adapted to be used in conjunction with similar pusher-type furnaces in a parallel array thereof.
Yet another object of the instant invention is to provide an improved method of operating a pusher-type furnace installation which permits accommodation of individual furnace programs to workpieces of different width without inconveniencing the operation of the entire system.
SUMMARY OF THE INVENTION The invention is based upon the discovery that, with existing installations of the character described, it is difficult, if not impossible to adjust the program of a particular furnace constituting part of an array of pusher-type furnaces adapted to be simultaneously operated to discharge onto a common conveyor arrangement. It will be readily understood that a change in the program is called for when any of the aforedescribed parameters is to be changed. For example, when narrow billets are to be heated, the periodic feed timing of the furnace must be adjusted to advance the workpieces more rapidly through the furnace and vice versa. It follows that, with the existing systems, it was not possible to vary the width of the workpieces supplied at one of the furnaces to the exclusion of the others. Hence the versatility of the entire system was limited.
It has now been found that this disadvantage can be overcome by providing, at the charging end of a pusher-type furnace, a table or platform for storage of the workpiece and, in addition to the main pusher mechanism or ram means, an auxiliary pusher mechanism or ram means of a stroke and periodicity which may differ from one furnace to another while the strokes of the main rams and their operating rates may be identical.
According to an essential feature of this invention, the auxiliary ram at the or each furnace operates at a rate which is equal to or greater than the rate of operation of the main pusher means.
According to an important feature of this invention, a pusher-type furnace, which extends longitudinally between an inlet and an outlet and provided with means for supporting a succession of workpieces between the inlet and the outlet in contiguous relationship, if formed adjacent its inlet with a collecting table juxtaposed with or adjacent a feed conveyor adapted to carry a succession of workpieces to the furnace. The feed-pusher means (auxiliary ram) is longitudinally reciprocable to displace a plurality of such workpieces generally transversely to the direction in which they are delivered, onto the collecting table for temporary storage thereon, during a stroke of the main pusher means which delivers a previous workpiece, or group of workpieces, to the furnace and thereby displaces all of the workpieces within the furnace through a corresponding distance in the direction of the outlet.
The conveyor means may be a gravity roller conveyor upon which the elongated workpieces are delivered in a direction parallel to their major dimensions and transversely to the longitudinal direction of the furnace.
The direction of reciprocation of the main pusher means andof the feed pusher means is, of course, transverse to the major dimensions of the workpieces but parallel to the longitudinal direction of the furnace, i.e.
in the direction of the inlet and in the direction of movement of the workpieces through the furnace from the inlet to the outlet.
According to the principles of the invention, the main pusher means is operated at a constant rate regardless of the program of the furnace while the feed pusher means'is operated at a rate determined by the I width of the workpieces to be heat-treated. Hence, the feed pusher means may deliver single workpieces to the collecting table for each stroke of the main pusher means when such workpieces have the maximum width which may be accommodated, or may be operated at a frequency or rate which exceeds that of the main pusher means to accommodate a plurality of workpieces upon the collecting table for each stroke of the main pusher means. This latter mode of operation is used when the width of the workpieces is less than the maximum width as will be apparent hereinafter.
The term main pusher means" is used herein to designate the pusher arrangement commonly provided at such furnaces in prior art systems and generally includes a drive speed-reducing gearing and one or more pusher bars reciprocated by such gearing. The drive may be independent from or coupled with the drives of similar furnace installations.
Theauxiliary ram or feed-pusher means, additionally provided in accordance with the principles of the the main pusheris reduced in accordance with the principles of this invention, additional place is available for storage of billets, etc.
Still another feature of this invention resides in the provision of swinging flaps, pawls or dogs upon the pusher bars, to enable them to clear the workpieces when the pusher bars are drawn away from the furnace inlet and to engage the workpieces along their trailing edges when the workpieces are to be advanced in the direction of the furnace inlet.
DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:
FIG. 1 is a vertical cross section through a pushertype furnace installation embodying the present inventlOn ;j'-
. FIG. 2 is a plan view thereof; g
FIG. 3 is a detail view of a pusher-ram'for use in the installation of FIGS. 1 and 2; "and FIG. 4A'-- 4H are diagrammatic side elevational views illustrative of various phases of the invention.
SPECIFIC DESCRIPTION Referring first to FIGS. land 2 of the drawing, it will be apparent that the furnace installation, which may comprise a plurality of parallel pusher-type furnaces only one of which has been illustrated, basically includes the pusher-type furnace 1 having a preheating chamber 1a, a main heating chamber 1b and a temperature-equalizing chamber 10 horizontally spaced along a linear transport path 1d for a succession of bars, billets, blooms or other prismatic workpieces of iron, steel or other metal .to be rolled. The workpieces are generally shown at'3 and have a length L and a width w or W as illustrated in FIG. 2. Some of the billets may, of course, be wider than others as represented in FIG. 1. The support 1d maybe concentrated by a pair of rails extendpresent invention, preferably includes an ,independently operable second drive means, e.g. a motor, speed-reducing. gearing and control means, for reciprocating the pusher bars of the feed-pusher means. The second drive means may be included in the same structure as the drive means for the main pusher bars or in a separately provided auxiliary structure. Since only individual workpieces need be displaced by the feed-pusher means, the drive for the latter and the pusher bars themselves may be diminished to withstand substantially less stress than is applied to the main pusher means. Furthermore, since the main-pusher means does not have to shift the workpieces onto the table, the stroke thereof can be reduced and the main pusher operated at a slow speed convenient to the optimal efficiency of the drive means.
The system has been found to be particularly advantageous when the furnace installation is used as part of a broad-band or strip rolling mill for heating the billets prior to rolling. The improved feed arrangement for the furnace installation may have its. program adjusted in accordance with the widths of the workpieces to be processed without negative influence upon the remainder of the processing line. Since the stroke of ing across heating chambers in the manner described and illustratedin the aforementioned US. patents.
. At the charging side of the furnace, there is provided an inlet door 1e beyond which an accumulating storage or collecting platform or table 5 extends horizontally in alignment with the upper surface of the workpiece supports within the furnace. The table 5 has a width D in excess of the maximum width W of a workpiece to be accommodated by the furnace and equal at least to the maximum stroke of the main pusher-ram 7 as will be apparent hereinafter. The exhaust-gas outlet is represented at 1 f and a furnace chamber is shown at 1g.
Each of the pusher-type furnaces 1 is disposed between .a pair of conveyors generally indicated at 4 and 12 and respectively constituting the inlet and discharge conveyors, respectively. The roller conveyors are inclined downwardly in the direction of advance of the workpieces as described at pages 10 74 ff. of MARKs MECHANICAL ENGINEERS Handbook, McGraw Hill Book Co., New York 1958. The conveyors 4 and 12 run along the entire bank of pusher-type furnaces in the usual manner and define a support plane P which is identical with that of the upper surface of the table 5. At the discharge side of the furnace, an outlet opening 1h is provided, together with a support table lj, the upper surface of which is coplanar with the uppermost portions of the rollers 12 of the discharge conveyor.
From FIGS. 1 and 2, it will be apparent that-each of the workpieces 3 travels along the charging conveyor 4 across the open mouth of the pusher-type furnace in the direction parallel to its length, in the direction represented by arrow A and is advanced into the furnace 1 in the direction of arrow B, thereby bringing its longitudinal edge 3' into contact with the rearward edge 3" of the previous workpiece. Continued movement of the workpiece 3 to the right (FIG. 2) pushes the entire collection of laterally contiguous workpieces to the right and thereby advances the workpiece at the distal end of the furnace out through the door 1h onto the table lj and finally onto the conveyor 12 where it runs by gravity in the direction of arrow C to a rolling mill or the like- The feed means for the workpieces is constituted, ac
cording to the present invention, by a main ram having a'pair of pusher bars 6 which may be reciprocated in the longitudinal direction of the furnace l, i.e. in the direction of arrow D, but which lie in a horizontal plane above the plane P of the table 5. At the free ends of the pusher bar 6, proximal to the furnace, there are provided swingable shoes 7 adapted to engage the trailing edges of the workpieces and advance them into the furnace. A suitable arrangement of this shoe is shown in FIG. 3 which also discloses that the bars 6 may be constituted as racks 6a engageable by pinions 6b coupled with an adjustable drive 11 which may be provided with a heavy-duty motor by speed-reducing gear with the pusher bar to deliver the relatively high torque necessary to advance all of the workpieces within the furnace. The drive 11 is, of course, shown only diagrammatically and may be constituted by the common drive for the main pusher members of all the furnaces of the respective bank. 7
Referring further to FIG. 3, it will be seen that the free ends of the bars 6 are bifurcated with the pawl-like flap 7 articulated in a slot 6c between the arms 6d of the bifurcation upon a pin 6e. When the bar 6 is retracted (arrow E) and the pawl 7 engages the forward or leading edge of a laterally shiftable workpiece as represented at 3' in FIG. 3, the pawl 7 swings in the counterclockwise sense to clear the workpiece and returns into its dot-dash line position in the clockwise sense only after the workpiece has been cleared. Furthermore, the trailing edge 7 of the pawl is designed to abut floor 6f of the bifurcation during the following forward displacement of the bar 6 when the leading edge 7" of the pawl engages the trailing edge 3 of the workpiece 3. Upon such abutment, the pawl cannot swing in the clockwise sense and hence the workpiece is entrained along with the pawl. A similar self-clearing pawl is provided at the free end of each of the spaced-apart rams 6. A second bar of rams 9 is provided between the rams 6 and constitute the auxiliary pusher means of the present invention, designed to advance the workpieces from the conveyor 4 onto the table 5 as will be apparent hereinafter. The stroke of the main pusher means may, of course, be reduced of the stroke of auxiliary pusher means. The auxiliary pusher means 9 comprises a pair of pusher bars or rams, spaced transversely across the mouth of the furnace and substantially coplanar with the rams 6 although a vertical offset has been represented in FIGS. 4A 4H for clarity of illustration. At the free ends, the bars 9 are provided with swingable pawls 10 as previously discussed. The drive means for the bar 9, may include a rack and pinion arrangement of the type represented in FIG. 3, and makes use of a motor 8 and appropriate speed-reducing gearing. The speed-reducing gearing, rack and pinion arrangements and control means are provided within the housing shown at 2, the latter reference numeral being used hereinafter to designate the workpiece-feed means generally.
The operation of the system will be understood more readily from FIGS. 4A 4H in which a typical sequence is shown. A workpiece arriving upon the gravity roller conveyor 4 generally will have a maximum width Wand is shiftable to the right onto the table 5 by the rams 9 and is thereafter advanced into the furnace by the rams 6 until, of course, the furnace is full. During movement through the furnace, the workpieces are heated to rolling temperature so that, when a further workpiece is pushed into the furnace, a workpiece of corresponding width is pushed out of the furnace onto the conveyor 12 and passes by gravity in the'direction of arrow C to the rolling mill. When, however, it is desired to reduce the width of theworkpiece to the width w, which preferably constitutes a simple fraction of the width W, i.e. w (l/n) X W, where n is an integer, n workpieces are accumulated upon the table 5 and are advancedsimultaneously into the furnace by the rams 6. In this case, the rams 9 may operate at a frequency f n X F, where F is frequency of operation of the main pusher rams 6.
For the heating of billets or other workpieces of a width W corresponding to the maximum width of the workpieces to be processed, the auxiliary pusher means 9, 10 shifts to the right (FIGS. 1 and 2) to displace the workpiece from the gravity roller conveyor 4 along which the workpiece travels in the longitudinal direction A. The workpiece is thereby moved transversely onto the table 5 whereupon the main pusher means 6, 7 engages the trailing edge of the workpiece and moves it to the right into the furnace by a distance approximately equal to W. All of the workpieces within the furnace are thereby shifted to the right and the workpiece 3a at the discharge end is thereupon pushed out of the furnace onto the table lj and, subsequently, onto the roller conveyor 12 which carries it in the longitudinal direction C to the rolling mill.
When it is desired to change the rolling program and, for example, make use of billets or workpieces of a smaller width w, e.g. a workpiece having a width w k W (n 2) the drive 8 is operated to effect two strokes of the feed pusher 9 as best seen in FIGS. 4A 4H. Assume, in FIG. 4A that the main pusher 6 is advancing the workpiece 3 in the direction of arrow B into the furnace from the table 5 as previously described. Simultaneously, the pusher 9 is operated with a smaller stroke in the same direction to advance a workpiece 3c of smaller width in the direction of arrow B onto the table. When two such workpieces 3c and 30' have been deposited upon the table, the pusher 6 moves rearwardly (arrow B so that its pawl 7 rides over the workpieces 3c and 30' to engage the rearrnost of these a 7 workpieces (FIGS. 4B and 4C) collected upon the table 5 as the pusher 9 begins its rearward movement (arrow B With pusher 9 continuingits rearward movement, the pawl 7 locks in place (FIG. 4D) against its abutment and the pusher 6 begins itspower stroke (arrow B to carry the two workpieces into the furnace with a totalstrokefof approximately W. Meanwhile pusher 9 accumulates additional workpieces upon the table as'shown in FIGS. 4E 4H and the cycle is repeated. The latter Figures also demonstrate that substantially any number of workpieces can be collected on the table depending, of course, upon the total stroke S of the main pusher. With a stroke S, which may be approximately equal to W, the largest workpiece width accommodated by the apparatus, the stroke of the main pusher may remain unaltered while workpieces are discharged from the furnace outlet in a cumulative width Wor S.
The improvement described and illustrated is believed to admit-of many modifications within the ability of persons skilled in the art, all such modifications being considered within'the spiritand scope of the invention except as limited by the appended claims.
1 A pusher-type furnace installation comprising:
a pusher-type furnace having an inlet at one end and I an outlet at another end thereof and provided with V means for supporting a succession of workpieces in contiguous relationship within said furnace; a collecting table ahead of said inlet; feed-pusher means for advancing a plurality of workpieces,
onto said table in the longitudinal direction of said furnace; and
8 I main pusher means for simultaneously advancing the workpieces onto said table into said furnace while shifting the workpieces therein a corresponding distance said outlet,
said main pusher means comprising: a main pusher bar reciprocable in saiddirection,
first drive means operably'connected with said main pusher'bar, w e v a pivotal pawl on said main pusher bar adapted to I ride over workpieces onsaid table and to lock upon advance of said ma-pusher bar in the direction of said inlet; said feed-pusher means including: 7 a feed-pusher bar reciprocable insaid direction, .second drive means operableindependently of said first drive means and connected to said feed-pusher bar for reciprocating same during reciprocation of said main pusher bar, and a pivotal pawl on said feed-pusher bar adapted to ride over workpieces upon displacement of said feed-pusher bar away'from said inlet and to engage the workpieces upon advance of the feed-pusher bar in the direction of said inlet. '7 v 2. The installation defined in claim 1 wherein said 4. The installation defined in claim 1 wherein a gravity roller conveyor is provided adjacent said table for r delivering said workpiec es t o sa id feed-pusher means.