U.S. patent number 3,867,748 [Application Number 05/449,192] was granted by the patent office on 1975-02-25 for supporting and driving frangible rollers.
This patent grant is currently assigned to Libbey-Owens-Ford Company. Invention is credited to Alfred H. Miller.
United States Patent |
3,867,748 |
Miller |
February 25, 1975 |
SUPPORTING AND DRIVING FRANGIBLE ROLLERS
Abstract
Cylindrical ceramic conveying rollers, with special end
connections to metal shafts that support the rollers for power
rotation through an adhesive.
Inventors: |
Miller; Alfred H. (Toledo,
OH) |
Assignee: |
Libbey-Owens-Ford Company
(Toledo, OH)
|
Family
ID: |
23783259 |
Appl.
No.: |
05/449,192 |
Filed: |
March 7, 1974 |
Current U.S.
Class: |
432/246; 198/780;
65/370.1; 198/789 |
Current CPC
Class: |
C03B
35/186 (20130101); C03B 35/165 (20130101); C03B
35/181 (20130101) |
Current International
Class: |
C03B
35/00 (20060101); C03B 35/16 (20060101); C03B
35/18 (20060101); B60b 015/16 () |
Field of
Search: |
;29/132,115,129.5,125,110,123 ;432/246 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Guest; Alfred R.
Attorney, Agent or Firm: Collins, Oberlin & Darr
Claims
I claim:
1. In a conveyor roller usable in the heat treatment of glass
sheets and which includes a ceramic cylinder, shafts located at and
in alignment with the ends of said cylinder, and means for
drivingly connecting said cylinder with at least one of said
shafts; the improvement in which said connecting means comprises a
cylindrical member rotatable with said one of said shafts and that
is in circumferential contact with said ceramic cylinder adjacent
an end thereof and partially encloses a cavity between said
cylindrical member and said ceramic cylinder; and a supply of a
heat expandable adhesive in said cavity.
2. A structure as defined in claim 1, in which means is provided
for relieving excess pressure in said cavity.
3. A structure as defined in claim 2, in which said pressure
relieving means comprises a passage formed between said ceramic
cylinder and said cylindrical member, and leading from said
cavity.
4. A structure as defined in claim 1, in which a wall of said
cylindrical member is circumferentially grooved to form said
cavity, and said cylindrical member is provided with
circumferentially arranged lands at either side of said cavity
designed for mating engagement with a surface of said ceramic
cylinder.
5. A structure as defined in claim 4 in which said wall of said
cylindrical member is also grooved longitudinally thereof to
provide pressure relieving passages leading from said cavity
between said cylindrical member and said ceramic cylinder.
6. A structure as defined in claim 4, in which said cylindrical
member is hollow and embraces said end of said ceramic cylinder and
said cavity is formed by a circumferentially arranged groove in the
inside wall of said member.
7. A structure as defined in claim 4, in which said ceramic
cylinder is a tube and said cylindrical member is a solid member
fitting into said end of said tube, and said cavity is formed by a
circumferentially arranged groove in an outside wall of said
member.
8. A structure as defined in claim 6, in which said drivingly
connecting means further comprises a hub on said one shaft having a
surface thereon adapted to matingly engage a corresponding surface
on said hollow cylindrical member, and said hub is connected to
said cylindrical member for sliding but not rotative movement
relative thereto.
9. A structure as defined in claim 8, in which said engagable
corresponding surfaces are tapered.
10. A structure as defined in claim 1, in which said shafts are of
metal, said ceramic cylinder is of fused silica, and said adhesive
has an expansion of approximately 114 .times. 10.sup.-.sup.6.
Description
BACKGROUND
1. Field of the Invention
The present invention relates to frangible conveying rollers
designed for use in the heat treatment of glass sheets and, more
particularly, to improved means for supporting ceramic surfaced
rollers within a heated furnace or kiln and for connecting them to
a source of power.
2. Description of the Prior Art
It has been customary to utilize power rotated metal rolls to
convey glass sheets, for example, through heat treating apparatus
of various kinds but, more recently, rollers having ceramic work
contacting surfaces have been found to give notably improved
results when employed for this purpose.
However, because of certain physical characteristics of ceramic
materials, including difficulties in working them, and their
frangibility, the use of such rollers has created new problems in
connection with accurately supporting them in highly heated
environments while, at the same time, adequately connecting them
with the types of drive means required.
SUMMARY OF THE INVENTION
According to the present invention there is provided a conveyor
roller comprising a frangible work contacting surface, supporting
shafts or trunnions for the roller, and special, readily engagable
connections between the roller and its shafts that are capable of
adequately transmitting power to rotate the roller, either
intermittently or continuously, under high temperature
conditions.
More specifically, it is an important object of the invention to
provide, in such a roll structure, a connection between the
frangible part of the roller and its supporting shafts that
includes a layer of a heat expandable adhesive material.
Another object is the provision in such a driven or rotated roller,
of means for relieving excess pressure that may develop within the
expandable adhesive.
Still another object is to provide a roller of the above character,
that utilizes a ceramic cylinder as a work support, in combination
with metal shafts having connecting portions provided with surfaces
that are associated with a surface of the ceramic cylinder in a
manner to permit it to be driven through a layer of adhesive
confined between the associated surfaces.
Further objects and advantages of the invention will become
apparent during the course of the following description when taken
in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, wherein like numerals are employed to designate
like parts throughout:
FIG. 1 is a transverse, vertical, sectional view through one end of
a glass tempering furnace that is equipped with a series of the
rollers of the invention as a conveyor for a succession of glass
sheets being tempered;
FIG. 2 is a perspective view of one form of the rollers of the
invention, with portions broken away to show the connection between
the shafts and the tube type ceramic cylinder;
FIG. 3 is a view similar to FIG. 2, showing a modified form of
connection;
FIG. 4 is a view similar to FIGS. 2 and 3, but with the ceramic
cylinder or tube broken away at the opposite end to show still
another form of connection;
FIG. 5 is a longitudinal, vertical, sectional view through another
form of the rollers of the invention, and through the mounting and
driving means therefor;
FIG. 6 is a perspective view of the roller of FIG. 5 with portions
of its ends broken away and portions shown in section to more
clearly illustrate the connecting means between the ceramic tube
and the shafts.
FIG. 7 is a vertical, sectional view through a modified form of
mounting for the rollers of the invention, designed to facilitate
rapid connection between the mounting and/or drive means and the
supporting shafts for the rollers.
FIG. 8 is a vertical sectional view of a roller similar to that
shown in FIG. 2, but with a shaft thereof structured to coact with
the structure of FIG. 7 to permit quick connection of the roller
supporting shaft to an extension thereof within the mounting
means.
FIG. 9 is a sectional view through one end of a roller similar to
that of FIG. 2, but in which the ceramic cylinder is provided with
a reduced end portion to permit its reception within an end cap of
reduced diameter.
FIG. 10 is also a section view through one end of a roller similar
to that of FIG. 2 but illustrating the use of a solid instead of a
tube type ceramic cylinder.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now more particularly to the drawings, there is
illustrated in FIG. 1 the heating end 10 of a generally
conventional glass sheet tempering furnace 11 which comprises
essentially a horizontal tunnel 12, enclosed by refractory side
walls 13, floor 14 and roof 15, and heated by suitable gas or
electric heating elements 16. Positioned transversely of the tunnel
12 are a series of conveyor rollers 17, arranged side by side in
parallel relation, and adapted to be rotated so as to carry a
succession of glass sheets to be tempered into and through the
heating end 10 of the tunnel 12 and toward and into the chilling
end of the tempering furnace (not shown).
The opposite ends of the rollers 17 extend outwardly of the tunnel
12, through openings 18 in the side walls 13, and are provided with
supporting shafts 19 and 20, journaled in bearings 21 that are
supported on channel irons 22 and 23, carried by plates 24 at the
upper ends of vertical I beams 25 or other suitable supporting
elements. To enable the rollers 17 to be power driven, worm wheels
26 are keyed to the outer ends, or to suitably connected
extensions, of the shafts 19; and in position to be drivingly
engaged by worm gears 27, keyed to a drive shaft 28 running along
and suitably mounted for rotation adjacent a side wall 13.
Adequate means (not shown) are provided for vertically adjusting
the bearings 21 to insure proper horizontal alignment of the ends
of each individual roller and of the horizontal alignment of each
roller with the other parallel rollers in the series; and the
channel iron 23 may be made wider and additionally supported by a
bracket or the like 29 to accommodate means for axial adjustment of
each of the rollers 17 for aligning it with the other rollers of
the series or for adjusting the roller shafts and/or associated
parts relative to the roller itself.
In operation, glass sheets 30 to be tempered are fed successively
over the rollers 17 into the tunnel 12 at the heating end 10 of the
tempering furnace 11, and the rollers 17 are rotated by power, from
a source (not shown), transmitted through drive shaft 28, worm
gears 27, wheels 26 and shafts 19, to move the glass sheets 30 into
and through the furnace. Within the furnace, the sheets are heated,
while passing through the heating end 10, to substantially the
softening point of the glass before they reach the cooling or
tempering end where the hot sheets are rapidly chilled by blasts or
jets of cooling fluid directed against opposite surfaces thereof
and acting to place the interior of the sheets in tension and the
exterior in compression.
Up to this point, the description of much of the apparatus
ancillary to the present invention would apply as well to other
types of known and conventional glass sheet tempering equipment.
Similarly, the rollers 17 of this invention can be provided with
ceramic work contacting surfaces by employing in these rollers
hollow ceramic cylinders or tubes 31 of the same general character
as is also shown in U.S. Pat. No. 3,608,876.
However, as well, the ceramic cylinders may be of a solid or bar
type, and the present invention departs radically from the prior
art both in its particular combination of the elements that make up
the complete roller structure, and in the manner in and the means
by which the supporting and driven roller shafts are connected to
the work supporting element of the roller.
Thus, in a preferred form of the invention the ceramic cylinders 31
are of fused silica or quartz. Further, as illustrated in FIG. 2 of
the drawings, the cylinders 31 are connected to the shafts 19 and
20 by hollow cylindrical end caps 32, carried on the inner ends of
the shafts, and which are adapted to fit over and encompass the
ends of the quartz cylinders.
One of the primary problems of other workers in this art has been
to provide a satisfactory driving connection between a ceramic roll
and any kind of a metal end on the roll shafts; and this has been
complicated by the facts that such connections must withstand not
only the furnace operating temperatures and a cycling roll drive
but also differences in expansion of the several roll parts which
make it difficult to hold accuracy. However, an eminently
satisfactory connection is obtained with the structure of FIG. 2 by
making the inner cylindrical surfaces of the end caps 32 slidable
over the ends of the quartz cylinders or tubes and by providing
cavities 33 in the caps' inner surfaces for receiving a supply of a
heat expandable adhesive material.
The cavities 33 must be of a character to confine the adhesive
between the inner cylindrical surfaces of the end caps 32 and the
outer cylindrical surfaces of the ends of the quartz tubes 31 and,
in the embodiment of FIG. 2, this is achieved by making each cavity
33 in the form of a circumferential groove spaced inwardly from the
open end of each cap. A preferred adhesive for use with this
embodiment is General Electric's RTV 60 silicone rubber cement,
which has an expansion of 114.0 .times. 10.sup..sup.-6 as compared
with 0.3 .times. 10.sup.-.sup.6 for quartz and 6.5 .times.
10.sup.-.sup.6 for mild steel; and, as a safety valve, a series of
circumferentially arranged, spaced recesses or passageways 34
leading from, and serving to vent, the cavity 33 to the open inner
end of the cap 32, and which leave lands 35 therebetween for mating
with the quartz tube, are provided.
In readying the roller of FIG. 2 for use, a batch of the RTV
silicone rubber cement, with nine drops of catalyst for each 50
grams of batch is made up. After heating the end caps 32 to between
150.degree. and 200.degree. F., the cavities 33 in each cap is
filled with the cement. The mating surfaces of the quartz tube and
the end caps are then coated with a primer, produced by the Corning
Glass Works as their number QA 21011, and allowed to dry, after
which the roller is assembled by sliding the end caps over and onto
the ends of the tube. In this procedure, end caps with inside
diameters equal to the outside diameter of the ends of the quartz
tube with which they are to be mated, minus 0.0003 to 0.0005 inch,
can be used; and this set up permits the end caps to be readily
assembled with the tube at temperature conditions of around
125.degree. to 150.degree. F.
The presence of the adhesive in the cavities 33 will provide an
effective driving connection between the quartz tubes and their
respective end caps under operating conditions while, at the same
time, any such excessive or objectionable pressure as might develop
within the adhesive or the cavities 33 and result in breaking of
the quartz tube will be relieved by venting or bleeding of adhesive
through the spaced passages 34. Also, if or when necessary, the
cavities 33 can be resupplied with adhesive through a suitable
injection hole or opening as shown at 36.
A modified, but similarly functioning form of the roller of the
invention is shown in FIG. 3 where the hollow ceramic tubes or
cylinders 31 are drivingly connected to the shafts 19 and 20 by
connecting structures 37 each of which includes a solid,
cylindrical, inner end portion 38 that fits into one of the open
ends of the ceramic tube and may be of a steel such as "Invar" with
an expansion of 0.9 .times. 10.sup..sup.-6. As was the case with
the hollow cylindrical end caps 32, the solid cylindrical members
38 are provided with circumferentially extending cavities 33A for
retaining supplies of adhesive, spaced passages 34A for venting the
cavities 33A when necessary, and mating lands 35A between the
spaced recesses; so that the connecting structures 37 function in a
similar manner to the end caps 32 and accomplish like results.
The form of the invention illustrated in FIG. 4 closely resembles
the form of FIG. 2 in that it involves end caps 42, as part of the
connecting structure between the ceramic tube 31 and the shafts 19
and 20, and that both of these end caps include circumferentially
extending adhesive cavities 33, spaced venting recesses or passages
34 and mating lands 35 that cooperate with the portion of the inner
mating surface of the end cap that lies outwardly of the cavity 33.
Indeed the cap 42 that is associated with the shaft 20 in FIG. 4
may be identical in structure with the caps 32 of FIg. 2. However
the other end cap 42 of FIg. 4, instead of being formed on the
inner end of its adjacent shaft, is associated with the shaft 19 by
means of a hub 44, which is secured to the shaft, as by pin 45, and
is keyed to the end cap as at 46.
Among the advantages of this construction are the fact that the
keyed connection between the hub 44 and the end cap 42 permits the
ceramic tube 31 to be separated from the shaft 19 without breaking
the adhesive connection between the end cap and the tube; and that
the rounded or spherical contour on the outer surface of the
flanged portion of the hub 44 can mate with a correspondingly
shaped portion on the inner periphery of the end cap and so
facilitate better alignment between the ceramic tubes and
shafts.
The form of the invention shown in FIGS. 5 and 6 are substantially
the same as that shown in FIG. 4, except that a hub 47 in the
latter two figures is carried by each shaft 19 and 20 and is
provided with a tapered surface 48 adapted to mate with a
corresponding tapered surface 49 of an opening through the outer
end walls of the end caps 50, and that these features facilitate
assembly of the roller parts and notably assist in avoiding
problems of misalignment.
Because the form of the invention illustrated in FIGS. 5 and 6
involve hubs that are keyed to and readily slidable into and out of
end caps on the ceramic tubes, a slightly different form of
mounting may be required than for the forms of the invention shown
in FIGS. 2 and 3. For example, as best shown in FIG. 5, the shaft
19 or an extension thereof on the drive side of the furnace 11 may
be mounted for rotation in a conventional manner in a fixed ball
bearing assembly 51. However the shaft 20, or its extension, at the
opposite end of the roller is mounted for rotation in a ball
bearing assembly 52 that is free to slide within the open inner end
of a hollow cylindrical housing 53, the outer end of which is
closed by a threaded plug 54.
With this arrangement, the several parts of each roll are
maintained in assembled relation during use by the action of a
compression spring 55 located in the housing 53 between the inner
ends of the slidable bearing assembly 52 and the closure plug 54.
The compression of the spring 55, which can be adjusted by
threading the plug 54 into or out of the housing 53, acts to
continually force the bearing assembly 52 toward the opposite or
drive side of the furnace and so to maintain the shafts, hubs, end
caps and ceramic tube of each roller pressed together in assembled
relationship.
At the same time any roller can be quickly and readily
disassembled, preferably by removing the plug 54 and spring 55, or
by threading the plug 54 outwardly, and slidably retracting one or
more of the several parts of the roll out of engagement with one
another.
A somewhat different form of fast connect-disconnect mounting
structure is illustrated in FIGS. 7 and 8 where an extension 56
(FIG. 7), for a supporting shaft 57 carrying an end cap 32 that
fits over the end of a ceramic cylinder 31 (FIG. 8), is mounted for
rotation within a conventional ball bearing assembly 58. The end of
the extension 56 facing the end cap 32 is in the form of a hollow
cylinder 59 which carries a drive pin 60 and a series of retaining
balls 61 that are themselves retained in operative position by a
retractible sleeve 62 mounted for sliding movement on the open end
59 of the extension 56. A compression spring 63 acts to normally
urge the sleeve 62 outwardly and into position to retain the balls
61 in their operative position as shown in FIG. 7 but, retraction
of the sleeve against the spring 63 will permit the balls to move
outwardly, and an enlarged portion 64 of the shaft 57 to be slid
past them into the hollow cylindrical end 59 of the extension 56.
At the same time the shaft 57 can be turned to permit a slot 65 in
its outer end to operatively engage the drive pin 60. At this time
the balls 61 will be in alignment with a circumferential groove 66
in the shaft 57 so that, upon release of the retracted sleeve 62,
the shaft 57 will be locked into driving position and engagement
with its extension 56. Similarly, driving disengagement and
disconnecting of the ceramic cylinder 31 can be effected by simply
retracting the sleeve 62 and pulling the shaft 57 out of the hollow
end 59 of its extension.
FIG. 9 illustrates the manner in which dimensional problems, such
as may be occasioned by close quarters or the necessity of making
an installation in a furnace designed for all-metal or other
different roller structures, can be overcome. Thus, as shown, a
smaller diameter of end cap 67 than that shown in FIG. 2, for
example, is used with a ceramic cylinder 68, that is of the size
intended for the larger end cap, by simply tapering the cylinder as
at 69 to give it a reduced diameter at its outer end 70 and so
accommodate the end cap 67.
Finally, FIG. 10 illustrates the manner in which a solid ceramic
cylinder or bar 71, of the character already discussed, can be
utilized with an end cap 32 of the type shown in FIG. 2.
Accordingly, it is to be understood that the forms of the invention
herein shown and described are to be taken as preferred embodiments
only of the same, and that various changes in the size, shape and
arrangements of parts, as well as various procedural changes, may
be made without departing from the spirit of the invention or the
scope of the following claims.
* * * * *