U.S. patent number 3,806,312 [Application Number 05/244,542] was granted by the patent office on 1974-04-23 for roller hearth furnace.
This patent grant is currently assigned to Frank A. Larimer. Invention is credited to Harold A. McMaster, Norman C. Nitschke.
United States Patent |
3,806,312 |
McMaster , et al. |
April 23, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
ROLLER HEARTH FURNACE
Abstract
A furnace of the type for heating sheet glass including a
housing supported by a framework. A pair of spaced parallel rows of
ceramic blocks are disposed in end to end relationship and extend
through the furnace. A pair of metal endless-loop belts are
entrained about wheels disposed exteriorly of the furnace with the
upper reach of each belt disposed upon and movable along the upper
planar surface of the ceramic blocks, the lower reach of each belt
being disposed exteriorly of the housing and supported by the
framework. A plurality of ceramic rollers rest upon and extend
between the belts and brackets and are disposed between the rollers
for preventing the rollers from moving longitudinally relative to
the furnace. Heating means are disposed within the furnace, and as
the steel belts move, the rollers rotate to move sheets of glass
through the furnace to be heated.
Inventors: |
McMaster; Harold A. (Woodville,
OH), Nitschke; Norman C. (Perrysburg, OH) |
Assignee: |
Larimer; Frank A. (Woodville,
OH)
|
Family
ID: |
22923191 |
Appl.
No.: |
05/244,542 |
Filed: |
April 17, 1972 |
Current U.S.
Class: |
432/121;
65/118 |
Current CPC
Class: |
C03B
29/08 (20130101); C03B 35/165 (20130101); C03B
35/163 (20130101); C03B 2225/02 (20130101) |
Current International
Class: |
C03B
29/00 (20060101); C03B 35/00 (20060101); C03B
29/08 (20060101); C03B 35/16 (20060101); F27b
009/24 () |
Field of
Search: |
;65/118,119
;432/246,121 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Camby; John J.
Attorney, Agent or Firm: McGlynn, Jr.; Gerald E.
Claims
We claim:
1. Apparatus for treating sheet material comprising: an elongated
housing; a conveyor assembly adapted to carry said sheet material
in a direction of travel substantially parallel to the longitudinal
axis of said elongated housing, said conveyor assembly including
first and second spaced apart support surfaces for establishing a
substantially planar surface extending in a direction substantially
parallel to the longitudinal axis of said elongated housing; a
plurality of elongated rollers extending transversely of said
elongated housing, each of said rollers spanning the gap between
said first and second support surfaces; and friction drive means
coupled with said rollers for effecting rotation of said rollers
whereby sheet material may be moved through said elongated housing
while supported by said rollers.
2. An apparatus as in claim 1 wherein said friction drive means
includes a belt disposed for movement over one of said first and
second support surfaces, said rollers being disposed upon said belt
such that said rollers are rotated upon movement of said belt.
3. An apparatus as in claim 2 including means for placing said belt
in tension.
4. An apparatus as in claim 2 including a control means for
limiting movement by said rollers in the plane of said belt.
5. An apparatus as in claim 4 wherein said control means allows
each roller to be lifted from said belt.
6. An apparatus as in claim 2 wherein said friction drive means
includes a second belt disposed for movement over the other of said
first and second support surfaces, said rollers being disposed upon
said second belt such that said rollers are rotated during movement
of said second belt.
7. An apparatus as in claim 6 including means for placing said
first and second belts in tension.
8. An apparatus as in claim 7 including means to synchronize
movement by said first and second belts.
9. An apparatus as in claim 6 including heat transfer means within
said elongated housing.
10. An apparatus as in claim 9 wherein said first and second belts
are disposed in relation to said rollers such that the portions of
said rollers adapted to contact said sheet material are entirely
between said belts and exposed continuously to said heat transfer
means.
11. An apparatus as in claim 6 wherein said belts are disposed
within said elongated housing.
12. An apparatus as in claim 4 wherein said rollers are disposed
entirely within said elongated housing.
13. An apparatus as in claim 6 including heat transfer means
capable of effecting a temperature gradient across said continuous
belts.
14. An apparatus as in claim 6 wherein said first and second
support surfaces are discontinuous and wherein said first and
second belts respectively bridge the discontinuities along said
first and second support surfaces.
15. An apparatus as in claim 14 wherein said discontinuities in
said first and second support surfaces define independently
adjustable support surface members disposed in parallel rows with
the individual support surface members of each row nearly abutting
one another in spaced end to end relationship.
16. An apparatus as in claim 15 wherein the ends of said rollers
are carried by and located relative to said support surface
members.
17. An apparatus as in claim 16 including adjustment means for
independently adjusting the longitudinal position of each support
surface member and the roller ends associated therewith.
18. An apparatus as in claim 6 wherein said rollers have
substantially equal diameters along the portions thereof engaging
said belts and along the portions thereof adapted to engage said
sheet material whereby the lineal velocity of said sheet material
will be substantially the lineal velocity of said belts.
19. An apparatus as in claim 6 wherein said first and second belts
are continuous and wherein said first and second belts are disposed
respectively for movement upon and over said first and second
support surfaces such that said first and second belts define said
substantially planar surface extending in the direction
substantially parallel to the longitudinal axis of said elongated
housing.
20. An apparatus as in claim 19 wherein said elongated housing is
insulated, includes heat transfer means within said elongated
housing, and wherein said rollers and said continuous belts are
disposed within the insulated portion of said housing.
21. An apparatus as in claim 20 wherein said friction drive means
includes a pair of spaced drive wheels disposed adjacent a first
end of said elongated housing, said belts being entrained about
said drive wheels, and a second pair of spaced wheels disposed
adjacent the second end of said elongated housing.
22. An apparatus as in claim 21 wherein said continuous belts
comprise chain link belts.
23. Apparatus for treating sheet material comprising: an elongated
housing; a pair of spaced parallel continuous belts, one of said
belts extending longitudinally of said housing along one side
thereof and the other of said belts extending longitudinally of
said housing along the other side thereof; a plurality of elongated
rollers extending transversely of said housing, each of said
rollers spanning the gap between and having end portions
respectively resting upon said belts; and drive means for effecting
movement of said belts to thereby effect rotation of said rollers
whereby sheet material may be moved through said housing while
supported by said rollers.
24. An apparatus as in claim 23 wherein said belts establish a
substantially planar surface upon which said rollers are
disposed.
25. An apparatus as in claim 24 wherein said belts are placed in
tension to establish the substantially planar surface upon which
said rollers are disposed.
26. An apparatus as in claim 25 wherein said belts comprise chain
link belts.
27. An apparatus as in claim 23 including control means for
limiting the movement of said rollers in the plane of said
belts.
28. An apparatus as in claim 27 wherein said control means allows
each roller to be lifted from said belts.
29. An apparatus as in claim 23 including a pair of parallel spaced
apart surfaces, one of said belts being disposed for movement over
one of said surfaces, the other belt being disposed for movement
over the other of said surfaces.
30. An apparatus as in claim 29 wherein said surfaces are
discontinuous and wherein said belts bridge the discontinuities
along said surfaces.
31. An apparatus as in claim 30 wherein said belts establish a
substantially planar surface upon which said rollers are
disposed.
32. An apparatus as in claim 31 including heat transfer means
within said housing.
33. An apparatus as in claim 31 including heat transfer means
capable of effecting a temperature gradient across said belts.
34. An apparatus as in claim 31 wherein said belts are disposed
within said housing.
35. An apparatus as in claim 34 wherein said rollers are disposed
entirely within said housing.
36. An apparatus as in claim 23 wherein the sheet contacting
portions of said rollers are entirely between said belts.
37. An apparatus as in claim 36 including means to synchronize
movement by said first and second belts.
38. An apparatus as in claim 37 wherein said housing is insulated,
includes heat transfer means within said housing, and wherein said
rollers and said continuous belts are disposed within the insulated
portion of said housing.
39. Apparatus for treating sheet material comprising: an elongated
housing; a continuous belt extending in a direction substantially
parallel to the longitudinal axis of said elongated housing; a
plurality of elongated rollers extending transversely of said
elongated housing, each of said rollers having a portion engaging
said continuous belt, the length of each of said rollers being
substantially greater than the width of said belt, said rollers
being adapted to support relatively wide sheet material throughout
the expanse of said sheet material in the direction transverse to
said elongated housing; and drive means for effecting movement of
said belt to thereby effect rotation of said rollers whereby sheet
material may be moved through said elongated housing while
supported by said rollers.
40. An apparatus as in claim 39 including means for placing said
belt in tension.
41. An apparatus as in claim 39 wherein said rollers have
substantially equal diameters along the portions thereof engaging
said belt and along the portions thereof adapted to engage said
sheet material whereby the lineal velocity of said sheet material
will be substantially the lineal velocity of said belt.
42. An apparatus as in claim 39 wherein said belt is disposed along
one side of said elongated housing.
43. An apparatus as in claim 42 including a second belt disposed
along the other side of said elongated housing, said rollers being
disposed upon said second belt such that said rollers are rotated
during movement of said second belt.
44. An apparatus as in claim 43 including means for placing said
first and second belts in tension.
45. An apparatus as in claim 44 including means to synchronize
movement by said first and second belts.
46. An apparatus as in claim 44 wherein said first and second belts
are disposed in relation to said rollers such that the portions of
said rollers adapted to contact said sheet material are entirely
between said belts.
47. An apparatus as in claim 43 including a pair of parallel spaced
apart surfaces, one of said belts being disposed for movement over
one of said surfaces, the other belt being disposed for movement
over the other of said surfaces.
48. An apparatus as in claim 47 wherein said surfaces are
discontinuous and wherein said belts bridge the discontinuities
along said surfaces.
49. An apparatus as in claim 48 wherein said belts establish a
substantially planar surface upon which said rollers are
disposed.
50. An apparatus as in claim 49 including control means for
limiting the movement of said rollers in the plane of said
belts.
51. An apparatus as in claim 50 wherein said control means allows
each roller to be lifted from said belts.
52. An apparatus as in claim 51 wherein said elongated housing is
insulated, includes heat transfer means within said elongated
housing, and wherein said rollers and said continuous belts are
disposed within the insulated portions of said housing.
53. Apparatus for treating sheet material comprising: an elongated
housing; a continuous belt extending longitudinally of said housing
along one side thereof; a plurality of rollers extending
transversely of and having axial central portions within said
housing; a plurality of spaced support surfaces extending along one
side of said housing; a plurality of roller retainers carried by
said support surfaces for respectively positioning said rollers;
adjustment means for each of said support surfaces for controllably
adjusting the position of said respective surface to thereby
respectively adjust the positions of the rollers associated with
said surface by said roller retainers; and drive means for
effecting movement of said belt to thereby effect rotation of said
rollers whereby sheet material may be moved through said housing
while supported by said rollers.
54. An apparatus as in claim 53 wherein said support surfaces
nearly abut one another in spaced end to end relationship.
55. An apparatus as in claim 54 including adjustment means for
independently adjusting the longitudinal position of each support
surface and the roller ends associated therewith.
56. An apparatus as in claim 54 including a second plurality of
spaced support surfaces extending along the other side of said
housing.
57. An apparatus as in claim 56 wherein said support surfaces are
disposed in two parallel rows with the surfaces of each row nearly
abutting one another in end to end relationship.
58. An apparatus as in claim 57 including adjustment means for
independently adjusting the longitudinal position of each surface
and the roller ends associated therewith.
59. An apparatus as in claim 58 including a second continuous
belt.
60. An apparatus as in claim 59 wherein each of said continuous
belts is disposed for movement over one of said rows of support
surfaces, said rollers being disposed upon said belts such that
said rollers are rotated upon movement of said belts.
61. An apparatus as in claim 60 including means to synchronize
movement by said belts.
62. An apparatus as in claim 60 wherein said belts establish a
substantially planar surface upon which said rollers are
disposed.
63. An apparatus as in claim 62 wherein said belts are placed in
tension to establish the substantially planar surface upon which
said rollers are disposed.
64. An apparatus as in claim 63 wherein said elongated housing is
insulated, includes heat transfer means within said elongated
housing, and wherein said rollers and said continuous belts are
disposed within the insulated portion of said housing.
Description
This invention relates to a furnace of the type utilized for
treating sheets of glass as by heating the sheets of glass for
tempering or annealing. One of the major problems associated with
such furnaces is the conveyance of the sheet of glass through the
furnace as the sheet of glass is heated to a temperature sufficient
for tempering or annealing.
One type of assembly for conveying sheets of glass through a
furnace which has been used in the past is one utilizing
rollers.
The simplest form of such roller conveyors in glass furnaces is one
wherein the ends of, or shafts extending from the ends of, the
rollers extend from the interior through the sides of the furnace
to external gears, pulleys, or the like, which rotate the rollers.
The problem with such assemblies is that it is very difficult to
maintain all of the rollers at the same rotary speed or the same
surface speed, i.e., the tangential speed in a plane tangent to the
tops of the rollers. Two rollers which are at slightly different
speeds or having different tangential speeds in engaging a sheet of
glass will mar the sheet of glass by rubbing. Additionally, there
are significant heat transfer problems when a portion of a roller
is within a very hot furnace and a portion extends exteriorly of
the furnace into ambient conditions. Sometimes the furnace has
holes therein to accommodate the rollers, and these holes make the
furnace very inefficient in that a great deal of heat is lost
through such holes.
Also, roller conveyors are known which are disposed entirely within
a furnace. However, the rollers are mechanically supported and
driven; thus, presenting the problem of keeping the rollers
rotating at the same speed, plus the problem of disposing the drive
means within the high temperature of the furnace. Such an assembly
is shown in United States Pat. No. 3,531,274.
There are other prior art conveyors which offer other advantages
but are not entirely satisfactory for conveying sheets of glass
through a furnace to be heated. One such conveyor is one wherein
the rollers are driven by belts. The problem with such conveyors is
that the rollers are separately mounted and it is difficult to
align the axis of the rollers so that there is a plane tangent to
the upper surface of all the rollers. Also, the various rollers are
frequently driven by different belts, thereby making it difficult
to keep the rollers all rotating at the same speed. Examples of
such conveyors are shown in the United States Pat. Nos. 1,883,426;
2,822,077; 2,827,153; 3,019,885 and 3,518,944.
Of course, one of the major disadvantages of using rollers which
are fixedly mounted is that in order to replace a defective roller
the furnace must be shut down. Another type of prior art assembly
which would alleviate this problem is one wherein the rollers are
freely supported on other rollers or stub shafts. The problem with
such assemblies is, of course, that it is very difficult to align
the stub shafts so that there is a plane tangent to the upper
surface of all the rollers supported by the stub shaft. Examples of
such prior art assemblies are shown in the United States Pat. Nos.
1,791,404; 1,923,815 and 2,023,126.
Accordingly, it is an object and feature of this invention to
provide an improved apparatus of the type for treating sheet
material including an elongated housing with a conveyor assembly
extending through the housing and including support surface means
for establishing a planar surface extending through the housing
with a plurality of rollers supported by the planar surface so that
the vertical position of the upper tangent of each roller is
determined by the planar surface and drive means for effecting
rotation of the rollers whereby sheet material may be moved through
the housing while supported on the rollers.
In correlation with the foregoing object and feature, it is another
object and feature of this invention to provide such an apparatus
wherein the drive means includes a belt means disposed upon and
moveable over the planar surface with the rollers being freely
disposed upon the belt means for rotation thereby so that the
planar surface and the taut belt establishes a precise plane upon
which the rollers roll.
In correlation with the foregoing objects and features, it is
another object and feature of this invention to provide control
means for limiting movement of the rollers relative to the housing,
whereby a defective roller may be merely lifted out of position and
replaced with a new roller.
In correlation with the foregoing objects and features, it is
another object and feature of this invention to provide such an
apparatus wherein the support surface means is defined by at least
one block the upper surface of which defines the planar
surface.
Other objects and attendant advantages of the present invention
will be readily appreciated as the same becomes better understood
by reference to the following detailed description when considered
in connection with the accompanying drawings wherein:
FIG. 1 is a fragmentary elevational view of a preferred embodiment
of the instant invention;
FIG. 2 is a fragmentary end view of the preferred embodiment of the
instant invention;
FIG. 3 is a fragmentary side elevational view partially broken away
and in cross-section of a module of the preferred embodiment of the
instant invention;
FIG. 4 is a fragmentary side elevational view of one of the blocks
utilized in the instant invention to define the planar surface over
which the belt moves to rotate the rollers and showing the control
means disposed between the rollers for limiting movement of the
rollers;
FIG. 5 is a fragmentary cross-sectional view taken substantially
along line 5--5 of FIG. 4;
FIG. 6 is a fragmentary view taken substantially along line 6--6 of
FIG. 5;
FIG. 7 is a view similar to FIG. 5 but showing an alternative
embodiment of the control means and the rollers;
FIG. 8 is an enlarged fragmentary cross-sectional view taken
substantially along line 8--8 of FIG. 7;
FIG. 9 is a view showing the drive wheels for driving the belt upon
which the rollers are supported in the preferred embodiment;
FIG. 10 is a view taken substantially along line 10--10 of FIG.
9;
FIG. 11 is a fragmentary elevational view of the second or idle
wheels at the other end of the furnace about which the belt is
entrained and showing tensioning means for applying tension to the
belt; and
FIG. 12 is a view taken substantially along line 12--12 of FIG.
11.
Referring now to the drawings wherein like numerals indicate like
or corresponding parts throughout the several views, a preferred
embodiment of the instant invention is generally shown at 20. As
alluded to above, the apparatus 20 is a furnace for treating sheets
of glass by heating the sheets of glass to temperatures sufficient
for annealing or tempering.
The apparatus 20 is of the type for treating sheet material and
includes an elongated housing defined by a plurality of modules
each of which includes a housing section 22, which is in turn
supported by framework 24. The housing 22 is defined by a metal
enclosure lined with firebrick so as to be insulated and includes
heat transfer means or heating means comprising the gas or electric
heaters 26, as shown best in FIG. 2. Each module of the housing
also includes a door 28 which may be raised to allow access to the
interior of the housing.
The apparatus also includes a drive wheel assembly, generally shown
at 30, disposed adjacent one end and exteriorly of the housing and
a second or idler wheel assembly, generally shown at 32, disposed
adjacent the other end exteriorly of the housing. A loading station
which is not shown is disposed adjacent the drive wheel assembly
30. An unloading station and a quenching or tempering section are
disposed adjacent the idler wheel assembly 32, neither of which are
shown. Such stations are well known in the art. Although the wheel
assemblies 30 and 32 are illustrated as being exteriorly of the
housing, they may of course be disposed within the housing.
The conveying assembly, which includes the drive wheel assembly 30
and the idler wheel assembly 32, also includes support surface
means for establishing a planar or support surface extending
through or within the housing. More specifically, the support
surface means is defined by a plurality of ceramic blocks 34 which
are disposed entirely within the housing. The blocks are narrow and
rectangular and the upper surface of the blocks define the planar
surface 36. There are a plurality of blocks 34 disposed in parallel
spaced rows to establish a pair of parallel spaced planar surfaces
36. The blocks are disposed in end to end relationship with a space
or gap between blocks.
The apparatus also includes a plurality of rollers 38 or 38'
supported by the planar surfaces 36 so that the upper tangent of
each roller 38 remains at a substantially constant distance above
the planar surface 36. In other words, each planar surface 36
establishes a plane for positioning the rollers 38 so that there is
another plane formed by the tangents to the upper surface of the
rollers 38 if all of the rollers are of the same diameter, or, said
another way, the planar surface 36 establishes a plane for
accurately positioning the rollers 38. The rollers are preferably
made of a material having a very low coefficient of thermal
expansion of not more than 1 .times. 10.sup.-.sup.6 /.degree. C as
well as excellent shock resistance. The rollers may be made of
fused quartz having a coefficient of thermal expansion of 0.54
.times. 10.sup.-.sup.6 /.degree. C. The temperature within the
furnace will normally be between 1,200.degree. and 1,400.degree.
F.
There is also included a drive means comprising the drive wheel
assembly 30, the idler wheel assembly 32 and belt means defined by
the belts generally indicated at 40. Each belt 40 has an active
upper or driven reach 42 and a vertically spaced lower or return
reach 44. As stated above, the entire drive means may be disposed
entirely within the housing to conserve heat and promote
temperature uniformity. The drive means effects rotation of the
rollers 38 whereby sheet material, as shown in phantom at 46, may
be moved through the housing while supported on the rollers 38. The
sheet material is normally defined by a plurality of discreet
sheets of glass although the assembly is suited to treating a
continuous sheet of material. The belts 40 are disposed upon and
movable over the planar surfaces 36 and the rollers 38 are disposed
upon the belts 40 and are rotated thereby. Thus, the rollers 38 are
supported on the planar surfaces 36 through the driven reaches 42
of the belts 40. The belts 40 are of a precise thickness and are
taut and straight and therefore the vertical position of the
rollers 38 is accurately determined and controlled; that is, it is
directly related to the planar surfaces 36. It will be appreciated
that because the belts are taut they will bridge gaps in the planar
support surface yet properly vertically position the rollers. As
stated above, there are spaces or gaps between adjacent blocks 34
which the belts bridge or span. In addition, the belts may be out
of contact with the planar surfaces substantial distances in the
event a block is not positioned properly or has non-planar surface,
as by having a valley between the ends thereof. Further, it will be
appreciated that even if the diameter of the rollers are different
from roller to roller, the tangential or linear surface speed of
the rollers will all be the same because all of the rollers are
rotated at the same tangential speed by the belts 40 which impart
rotation to all of the rollers.
The apparatus also includes control means comprising the brackets
generally indicated at 48 and 48' for limiting movement of the
rollers relative to the housing 22. Each bracket 48 and 48' extends
upwardly between adjacent rollers 38 and is entirely below the
uppermost point on the surface of the roller 38 so as not to
interfere in any way with the movement of the sheets of glass 46
through the apparatus. Each bracket 48 and 48' extends upwardly
from the planar surface 36 of the block 34 and is dipsosed between
two of the rollers 38. Each block 34 has a plurality of spaced
slots 50 extending downwardly thereinto from the upper planar
surface 36 on each side thereof, as that illustrated in FIGS. 5, 7
and 8. Each bracket includes a fence portion 52 which extends
across the planar surface 36 for limiting movement of the adjacent
rollers 38 longitudinally of the housing. Each bracket also
includes arms 54 extending downwardly from the fenced portions 52.
One arm of each bracket 54 is disposed in a slot 50 on one side of
a block 34 while the other arm 54 is disposed in a slot 50 on the
other side of the block. The lower extremity of each fenced portion
52 of each bracket 48 and 48' is disposed or spaced above the
planar surface 36 of the associated block 34 so that the upper
reaches 42 of the belts 40 are disposed on the planar surfaces 36
between the arms 54 of the brackets and spaced beneath the fenced
portions 52, as best illustrated in FIGS. 5 and 7. The bottoms of
the arms 54 of the brackets 48 shown in FIGS. 4 and 5 engage the
bottoms of the slots 50 to thereby vertically position the brackets
48. In contra-distinction, the alternative brackets 48' include
fingers 56, as shown in FIGS. 7 and 8, which extend laterally from
opposite sides of each arm 54 for engaging the planar surface 36
for vertically positioning the fenced portions 52 thereof. The
fingers 56 also function to hold the brackets 48' down when the
fences 52 thereof are engaged by a rotating roller because that
roller will be disposed above as over the adjacent fingers 56.
Additionally, the brackets 48' each include a flange 58 extending
laterally from one end of the fenced portion 52 thereof for
limiting longitudinal movement of the adjacent roller 38
transversely of the housing. The brackets 48' are identical so that
the brackets 48' along the planar surface 46 of one block 34 limit
longitudinal movement of the rollers 38 in one direction while the
brackets along the planar surface 36 of the outer spaced block
limit longitudinal movement of the rollers 38 in the other
direction. In other words, the rollers 38', as shown in FIG. 7,
have their longitudinal movement to the right limited by the
flanges 58' of the brackets 48' on the right, whereas movement to
the left is limited by the flanges 58 of the brackets 48' on the
left.
As shown in FIGS. 2, 5 and 7, the rollers 38 and 38' extend between
the two rows of parallel blocks 34 and have their ends disposed or
resting upon the active or upper reaches 42 of the belts 40. As
illustrated in FIGS. 5 and 6, the end portions of each roller 38
disposed over or resting upon the active reaches 42 of the belts 40
are smaller in diameter than the immediately adjacent portion in
the direction of the opposite ends for maintaining the rollers
properly positioned. More specifically, as illustrated, the rollers
38 have raised portions or ridges 60 extending thereabout which are
of a larger diameter than the end portions resting upon the active
reaches 42 of the belts 40. Therefore, should the rollers tend to
cock or move out of a position which is perpendicular to the
desired travel of the glass, a ridge 60 will contact the adjacent
belt and being of a larger diameter will move the roller faster,
thereby returning the roller to the proper alignment. When the
rollers are perpendicular to the belts the glass sheets will move
in a direction parallel to the belts; however, should the rollers
be non-perpendicular to the belts the sheets of glass will not move
parallel to the belts. Thus, the automatic alignment of the rollers
also automatically causes the sheets of glass to move parallel to
the belts as desired. It will be appreciated that all that is
necessary is a larger diameter portion adjacent the portion of the
roller engaging the belts in order to accomplish this purpose.
The rollers 38' differ from the rollers 38 in that although the
rollers 38 and 38' are made of ceramic, the rollers 38' are hollow,
as best illustrated in FIG. 8. The advantage of hollow rollers is
that the rollers will flex if they become eccentric or not
perfectly straight so that when a sheet of glass moves thereover
they will straighten instead of lifting the glass off of adjacent
rollers. Additionally, hollow rollers are less likely to sag under
their own weight.
It will be appreciated from the description thus far that should
one of the rollers 38 or 38' become defective all that is necessary
is that the defective roller be removed from the furnace between
spaced sheets of glass moving therethrough and replaced by a new
roller without at all disrupting the flow of sheets of glass
through the furnace.
Since the position of the upper planar surfaces 36 of the blocks 34
is very critical, requiring the blocks 34 to be properly
positioned, there is also included adjustment means for adjusting
the position of the blocks 34 so as to adjust the position of the
planar surface 36. As alluded to before, the blocks 34 are disposed
in parallel rows and the blocks of each row abutt one another in
end to end relationship with a space between the ends of adjacent
blocks. The framework 24 includes a pair of spaced and parallel
beams 62 which extend lengthwise below the housing 22. The
adjustment means includes a pair of first and second support shafts
64 and 66 wlich which connected to the beams 62 and extend into the
housing 22 to adjustably support the blocks 34. Each block 34 has
associated therewith a first support shaft 64 and a support shaft
66. Each block 34 includes a pair of lugs 68 extending downwardly
from the bottom surface. Each first shaft 64 has a channel 70 at
the upper end thereof engaging the lower extremity of and disposed
about opposite ends of one of the lugs 68 for moving the associated
block longitudinally of the housing upon arcuate movement of the
first shaft 64 about its connection to the beam 62. Each of the
second support shafts 66 has a plate 72 at the upper end thereof
engaging the lower extremity of the other lug 68 of the associated
block for allowing the block to move freely longitudinally of the
housing. In order to move the first support shaft 64 in an arcuate
path, the adjustment means also includes an eye bolt 74 having one
end or a ring 76 surrounding the first shaft 64 and operatively
connected to the adjacent beam 62 by a threaded shank and a channel
member 78. Longitudinal adjustment of the eye bolt 74 moves the
first support shaft 64 in an arcuate path to adjust the
longitudinal position of the associated block 34. It should be
appreciated that the arcuate movement of the first support shaft 64
is very minimal as the longitudinal movement of the blocks 34 for
adjustment is very minimal.
As alluded to hereinbefore, the housing includes a plurality of
modules disposed in end to end relationship, and each module has a
plurality of the blocks 34 disposed therein. FIG. 3 illustrates one
such module, and as illustrated the module includes two blocks 34
in each row for a total of four blocks 34. As mentioned
hereinbefore, the door 28 may be raised for providing access to the
interior of the housing. There are included compressible or
expandable sealing means disposed between the ends of adjacent
modules for allowing the modules to expand and contract
independantly of one another.
As is clear from the drawings, each belt 40 comprises an endless
loop having an active reach 42 disposed over the planar surfaces 36
of the blocks in one row, whereas the other reach or lower reach 44
is disposed exteriorly of the housing. A support means, which
includes a plate 80 and hangers 82 connected to the beams 62,
supports the lower reaches 44 of the belt 40.
The drive wheel assembly 30 includes a pair of spaced drive wheels
84 disposed adjacent a first end and exteriorly of the housing and
the belts 40 are entrained about the drive wheels 84. The idle
wheel assembly 32 includes a second pair of spaced wheels 86
disposed adjacent the other end and exteriorly of the housing and
the belts 40 entrained thereabout.
The belts 40 are preferably made of alloy steel or refractory metal
such as a chrome nickel alloy and the ratio of the diameter of the
wheels 84 or 86 to the thickness of the associated belt 40 is
preferably no less than 1,000 to 1 to prevent injury to the belts
by exceeding their elastic limits which for the annealed metals
preferably used is approximately 30,000 p.s.i. and the Youngs
Modulus 3 .times. 10.sup.7 p.s.i. It will be appreciated that the
belts may be made of other materials including chains and mesh.
The drive wheel assembly 30 also includes a pair of electric motors
88. Each motor 88 operatively drives one of the drive wheels 84
through a pinion 90 and a large gear 92. The pinion gear 90 is
driven through a gear box 94. The gear boxes 94 are best
illustrated in FIG. 10, and are coupled together by a coupler 96,
thereby coupling the drive wheels 84 together for rotation at the
same speed so that both belts 40 move at the same linear speed,
thereby rotating all of the rollers 38 at the same surface or
tangential speed.
The idle wheel assembly 32 includes a carriage means comprising a
frame 98 which supports rods or guides 100, which in turn support
the second pair of wheels 86 for movement longitudinally of the
belts 40. There is also included belt tensioning means comprising
the air cylinders 102 and cables 104 entrained about pulleys 106
for controlling the tension on the belts 40. The wheels 86 are
supported by housings 108 which are in turn slidably supported on
the rods 100, there being two rods 100 associated with each housing
108. Thus, the force applied through the cables 104 by the air
cylinders 102 determines the tension on the belts 40.
A crown is included in the wheels for centering the belt on the
wheels. In other words, the wheels 84 and 86 may have a crown
therein for centering the associated belt thereon.
Each drive wheel 84 is supported by a frame 110 and each frame 110
is in turn supported by a base 112. The frame 110 is supported on
the base 112 for pivotal movement about an axis extending through
the center line of the associated belt 40. More specifically, as
shown in FIG. 10, the forward portion of the frame 110 is connected
to the base 112 through a fastener or bolt 114, the center line of
which or longitudinal axis of which extends through the center line
of the associated belt 40. There is also included means, generally
indicated at 116, to pivot the frame 110 about the axis of the bolt
114 to adjust the position of the frame 110 relative to the base
112 to properly align the associated drive wheel 84. Bolts 118 lock
the bases 110 in the desired position.
As alluded to herein above, the surfaces of the belts 40 are
critical. For example, a small bit of grit or the like may be
disposed between the belt and the surface of one of the wheels 84
and 86 as one of the belts passes thereover to thereby cause a
bulge or dimple in the belt which would in turn cause undesirous
vertical movement of the rollers as the belt moves thereunder.
Therefore, the apparatus includes an abrasive means, generally
indicated at 120 in FIG. 3, for engaging the surfaces of the belt
for maintaining the surfaces of the belt within predetermined
tolerances. Such abrasive means will remove such dimples or similar
imperfections.
In some instances it may be desirous to heat the belt before it
enters the housing so that there is not a sudden rise in
temperature of the belt as it leaves ambient conditions and moves
into the housing. Furthermore, the belt in its natural state or due
to operating conditions may be slightly curved, and it therefore
may be desirous to heat the belt with heating means capable of
supplying heat with a temperature gradient across the belt as by
heating the belt along one edge as it is moving through the furnace
to straighten out the belt and guide it along the desired path.
Various heat transfer means may be utilized to provide such a
temperature gradient across the belt. A means for so heating the
belt exteriorly of the housing is generally shown at 122 in FIG.
9.
It also may be desirous to provide a lubricant between the ends of
the rollers 38 and 38' and the belts 40 and the brackets 48 and
48'. Such a lubricant accomplishes three purposes. First it
prevents excessive wear of the belt, particularly when the rollers
are made of ceramic. Secondly, should the glass be stopped or
retarded, lubrication between the belt 40 and the rollers 38 and
38' will allow slippage between the belt 40 and the rollers 38 and
38' instead of between the rollers 38 and a sheet of glass, which
would, of course, mar the surface of the glass. Thirdly, the
lubricant will retard or prevent wear of a roller should it be
prevented from rotating.
The invention has been described in an illustrative manner and it
is to be understood that the terminology which has been used is
intended to be in the nature of words of description rather than of
limitation.
Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is,
therefore, to be understood that with the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described.
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