Door for slab-heating furnace and the like

The specification discloses a door for a slab-heating furnace. A series of closure members are positioned in side-by-side relationship from one side of the opening to the other. Each closure member has one or more sections pivotally connected to an adjacent section.

This invention relates to doors for slab-heating furnaces and the like. 
More particularly, it relates to doors which are closed by gravity and are 
opened by movement of slabs into and out of the furnace. 
In the rolling of steel, it is often necessary to heat slabs, billets, bars 
and the like prior to hot rolling. Such heating may be required to raise 
the metal to a temperature suitable for hot rolling, or the heating may be 
needed to bring the metal to an even temperature throughout. Substantial 
heat is required for operation of such furnaces, and such furnaces 
represent a substantial expense and account for considerable heat loss in 
a mill. In order to conserve heat and to reduce operating expense, it is 
desirable to close the entrance and exit openings with a door which will 
restrict loss of heat except when a slab and the like is entering or 
leaving the furnace. 
I provide door means for a slab-heating furnace which substantially close 
the opening of the furnace in which the door is positioned. By "slab", I 
refer to metal, such as steel, which is in semi-finished form and may be 
called a "slab", "ingot", "billet" or other such term. I provide door 
comprising a plurality of closure members extending substantially from top 
to bottom of the furnace opening. I provide a plurality of closure 
sections hingedly connected to the top of the furnace opening. I further 
preferably provide a plurality of closures disposed in side-by-side 
relationship with each closure in juxtaposition to an adjacent closure 
without being connected thereto. 
I prefer to provide a door supporting frame which will hold all of the 
closure member in juxtaposition to one another. I prefer to provide hinge 
means comprising a plurality of alternating tongues on adjacent sections 
of a closure and pivot pin means having a horizontal axis extending 
through said tongues. 
Alternatively, I prefer to provide a door which is comprised of a plurality 
of door closure assemblies each having a door anchor and a plurality of 
closures which are arranged in side-by-side relation. Each closure 
comprises a plurality of vertically arranged sections which are supported 
by hinge means. The hinge means includes pivot pin means which are 
generally horizontal and project through each section to an adjacent 
portion of the closure assembly. 
Other details, objects, and advantages of my invention will become more 
apparent as the following description of a present preferred embodiment 
thereof proceeds.

FIGS. 1-4 show a door assembly which is supported from a metal frame 
comprising a horizontally extending lower channel 1 and a horizontally 
extending upper channel 2. The upper and lower channels are connected and 
braced at intervals by gussets 3. The metal frame may be connected in any 
convenient way to the framework of the furnace, and the frame may serve as 
a part of the furnace framework. The metal frame is positioned at the top 
of an opening in the furnace having sides 4 and 5. The bottom of the 
opening is defined by the furnace hearth 6. A series of anchor blocks 7 
are fastened to channels 1 and 2. The anchor blocks are placed 
side-by-side abutting one another, and as a group, they extend from one 
side of the furnace opening to the other across the top of the opening. 
Each anchor block has a depending centrally located tongue 8. 
A closure section 9 is supported beneath anchor block 7. Section 9 is 
generally rectangular. It has two upwardly extending tongues 10 which are 
positioned on opposite sides of tongue 8. A pivot pin 12 (FIG. 3) extends 
through tongues 8 and 10 on axis 12a (FIG. 2) and permits pivotal movement 
of section 9 relative to anchor block 7. A second closure section 13 has 
two upwardly projecting tongues 14 which are positioned on opposite sides 
of tongue 11. The lower surface 15 of section 13 clears hearth 6 by a 
small distance when the closure is hanging free as shown in FIGS. 1 and 2. 
A bevel 16 is formed on one lower corner of closure section 13. Closure 
sections 9 and 13 are pivotally connected together by pivot pin 17 on axis 
17a. 
Normally, the furnace door is in the position shown in FIGS. 1 and 2. In 
each closure, sections 9 and 13 hang down from anchor block 7 to the 
furnace hearth. Also, the closures extend across the entire width of the 
opening thereby closing the opening to escape of heat from the furnace and 
to entry of cold air into the furnace. Anchor blocks 7 and closure 
sections 9 and 13 are made of a heat-insulating ceramic material which 
will resist the furnace temperatures. 
When a slab is pushed through the furnace opening, its leading edge will 
contact section 13 or both section 13 and section 9. FIG. 3 shows a slab 
18 being pushed into the furnace in the direction indicated by arrow 19. 
Section 9 has been rotated about the axis of pivot pin 12 and section 13 
has rotated about the axis of pivot pin 17. Bevel 16 permits section 13 to 
rotate on the axis of pivot pin 17 without scraping on the hearth. As slab 
18 passes through the furnace opening, section 13 is flat on top of slab 
18 and section 9 has assumed an angle from the vertical sufficient for 
clearance of slab 18. In that manner, the space between the hearth and the 
top of the furnace opening continues to be closed by the slab and the 
closure sections. The only closure sections which are moved to the 
position shown in FIG. 3 are those which span the width of the slab. The 
closure sections to each side of the slab continue to hang in a vertical 
direction. 
It will be apparent that the furnace door construction permits slabs to 
enter or leave the furnace without power driven opening and closing 
equipment. At the same time, the construction leaves substantially all the 
area to each side of the slab closed. The door construction will 
automatically adapt to and accommodate slabs of different widths and 
heights. When a slab is entering or leaving the furnace, there is no open 
space above the slab for heat loss. 
In the embodiment of FIG. 4, only a single hinged section 9 is provided 
below the anchor block. The door which is constructed in that fashion is 
suited for installations where only a slab of moderate thickness will be 
charged to the furnace. 
FIGS. 5-7 depict another embodiment of my furnace door. Furnace front 100 
includes furnace structure 102 and furnace door 104 which comprises a 
plurality of closure assemblies 103. 
A single closure assembly 103, as shown in FIG. 7, includes anchor block 
106 which has a depending centrally located tongue 107. Three closures are 
supported from anchor block 106. As shown in FIG. 7, the closure to the 
left of tongue 107 comprises sections 108 and 110. The closure to the 
right of tongue 107 comprises sections 116 and 118. Directly below tongue 
107 is a third closure which comprises sections 112 and 114. Pivot pin 120 
hingedly connects sections 108 and 116 to tongue 107. Pivot pin 122 
hingedly connects sections 108, 112 and 116. Pivot pin 124 hingedly 
connects sections 110, 112 and 118. Pivot pin 126 hingedly connects 
sections 110, 114 and 118. The assembly of sections, along with tongue 107 
substantially closes the opening of the furnace. 
While six sections and four hinges have been shown and described, it is to 
be understood that any number of sections and hinges may be incorporated 
in a particular design depending upon the circumstances. Also, closure 
assembly 103 may comprise more or less than three closures depending upon 
specific needs. 
FIG. 6 shows the operation of one particular closure under the influence of 
slab 132 which is moving from the outside 134 of the furnace to interior 
136. As slab 132 proceeds from outside 134 to interior 136, leading edge 
138 engages surface 140 of section 110. That causes section 108 to pivot 
rowards interior 136 on hinge 120 and section 110 to pivot towards 
interior 136 on hinge 124. Surface 140 rides on top 142 of slab 132. When 
trailing edge 144 of slab 132 fully clears section 110, gravity causes 
sections 108 and 112 to pivot back to their original generally vertical 
positions. It may be appreciated that when slab 132 is proceeding from 
outside 134 to interior 136, the contact between face 140 and top surface 
142 substantially prevents heat from escaping from interior 136 to 
exterior 134. 
It is to be understood that each closure assembly 103 hangs independently 
from each adjacent closure assembly. That is because any particular pivot 
pin projects only from the left edge of its associated closure assembly to 
the right edge of the same closure assembly. No pivot pin projects between 
adjacent closure assemblies. Therefore, should a slab, of a width less 
than the width of furnace front 100, engage one or more closure 
assemblies, only those closure assemblies so engaged pivot open while the 
remaining closure assemblies would stay closed. That feature minimizes the 
amount of heat loss from the furnace when a slab is entering the furnace 
interior. 
The sections of the door are formed of a refractory material which will 
withstand furnace temperatures and mechanical stresses resulting from 
passage of slabs through the furnace opening. One door may be positioned 
at the slab entrance and another at the slab exit. The doors may be 
sheathed with stainless steel on one or both sides to protect the 
refractory material from direct contact with slabs entering and exiting 
the furnace. 
While I have illustrated and described certain present preferred 
embodiments of my invention, it is to be understood that I do not limit 
myself thereto and that my invention may be otherwise variously practiced 
within the scope of the following claims.