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.

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.

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.