US2631561A

US2631561A - Apparatus for continuously enameling thin sheet metal

Info

Publication number: US2631561A
Application number: US204156A
Authority: US
Inventors: Robert G Calton
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-01-03
Filing date: 1951-01-03
Publication date: 1953-03-17
Anticipated expiration: 1970-03-17

Description

March 17, 1953 R. e. CALTON 2,631,561

APPARATUS FOR CONTINUOUSLY ENAMELING THIN SHEET METAL 2 SHEETS-SHEET l Filed Jan. .3, 1951 llvvewroe Poet/er 6" mire/v T70R17! Y1 mum March 17, 1953 R. G. CALTON APPARATUS FOR CONTINUOUSLY ENAMELING THIN SHEET METAL Filed Jan. 5, 1951 2 SHEETSSl-IEET 2 Patented Mar. 17, 1953 APPARATUS FOR CONTINUOUSLY ENAMEL- ING THIN SHEET METAL Robert G. Calton, Nashville, Tenn.

Application January 3, 1951, Serial N 0. 204,156

2 Claims. 1

This invention relates to apparatus for porcelain enameling sheet metal and has more particular reference to apparatus for continuously applying porcelain enamel to thin sheet steel or thin sheet iron.

In the firing of porcelain enameled sheet iron of 20 gauge or lighter, it has been the practice to either support the article in a horizontal plane on spaced pins or the like, or to hang the article from hooks on a chain which carries the articles through a firing zone. It has never been possible heretofore to fire large flat pieces thinner than 20 gauge by either of these procedures without warpage. If the workpiece has rested on the conventional firing pins in a horizontal position, the base metal was softened during th firing operation to an extent sufiicient to cause sagging in the areas between the pins and noticeable deformation in the supported areas. A sheet thus fired with the base metal deformed will always show the presence of such deformed area because of the reflective nature of the porcelain enamel coating. Furthermore, the cooled sheet was severely warped and did not present an adequate flat surface. from hooks and fired by being carried through a furnace, the sheets usually warped, due, not only to the weight of the sheet itself, but also the inherent stresses which are present in the sheet. Thin sheets, that is, thinner than 20 gauge, when fired. in this Way, also tend to exhibit an overall "crinkled effect due to th unequal softening of the sheet in local areas and the internal stresses in the sheet, as aforesaid.

It is, therefore, a principal object of this invention to provide novel and improved apparatus for continuously porcelain enameling sheet metal ranging from 20 to 40 gauge, without the enameled sheet metal showing areas of deformation.

Another object of the invention is to provide apparatus, as above characterized, including means for controlling the tension of the moving sheet as it moves through the firing furnace to prevent buckling and warping thereof, due to the firing temperature.

A further object of the invention is to provide apparatus, as above characterized, including a firing furnace having an arch. for supporting and guiding the sheet during its travel therethrough.

Other objects and advantages of the invention will appear in the specification when considered in connection with the accompanying drawings, wherein:

Fig. l is a diagrammatic elevational view of the apparatus of the invention, with parts broken When the sheets have been hung away to show the interior of certain of the elements;

Fig. 2 is a diagrammatic plan view of the apparatus shown in Fig. l;

Fig. 3 is a detailed perspective view showing the manner in which the rollers are mounted; and

Fig. 4 is a detailed perspective view showing the manner in which the tension control idle rollers are mounted.

This invention is related to the subject matter of my co-pending application, Ser. No. 125,987, filed Nov. 2, 1949, and entitled Methods of and Apparatus for Porcelain Enameling Sheet Metal.

The present invention, insofar as it concerns the application of vitreous enamel or frit paste to a continuously moving thin sheet of metal and the firing of the coated sheet, is similar to the invention disclosed and claimed in my said copendins' application. Here, however, the similarity ceases, and many improvements and advantageous features are incorporated in the invention of the present application.

Referring now to the drawings, and more particularly to Figs. 1 2, there is shown a coiled roll. Ill of sheet metal ll, ranging from 20 to 40 gauge, mounted on a horizontal spindle Ill. The sheet passes through driven rollers I3 and then through a vat Is filled with a nickel sulfate solution of approximately 12 oz./ga1lon, the sheet being held below the surface of the solution by means of idle roller I 5.

From the nickel sulfate solution, the sheet passes over idle roller It, then through a drying chamber H, which may comprise heat lamps l8, or other suitable heatin elements, Where the sheet is dried. The excess nickel sulfate solution is wiped off both sides of the sheet as it emerges from the vat. From the drying chamber, the sheet passes through driven. rollers I9 into and through a vat 2i! filled with ground coat enamel slip or frit paste of any suitable composition, where the sheet is coated with a coating of the slip. The sheet is held below the surface of the slip by means of idle roller 2 i.

From the coating vat 20, the sheet passes over a rubber stripper or squeegee 22, which removes the enamel slip from the bottom of the sheet, and then through a firing furnace 23, shown diagrammatically as being heated electrically by resistors 2d. It is to be understood that the heat may be applied in any other suitable manner.

During its passage through the firing furnace, the sheet is supported by and slides over the up per surface of a metal arch 25. The arch 25 is wider than the sheet and is preferably made in three sections, an intermediate section 26 made of nickel alloy to Withstand the firing temperature, and end sections 21 made of any suitable material preferably metal. The upper surface of the arch is flat in transverse cross section.

rom the furnace 23 the fired sheet passes under 2. sag control device 28, through driven rollers 29, into a second coating vat identical to the vat 2d. The second coating vat is filled with cover coat enamel slip or frit paste of the desired color and composition. The sheet is held below the surface of the slip by means of idle roller 3i From the coating vat 3d, the sheet passes over a rubber stripper or squeegee 32, which removes the enamel slip from the bottom of the sheet, and then through a second firing furnace 33, which is identical in construction to the first firing furnace 23. During its passage through the second firing furnace 33, the sheet is supported by and slides over the upper surface of a metal arch which is identical in construction to the arch 25 in the first firing furnace.

The sheet emerges from the second firing furnace 33 as the finished product. As the finished product emerges from the second firing furnace 33, it passes under a second sag control device 35 and then through driven rollers 36. The sheet emerging from the driven rollers 36 may be cut to suitable length or rolled into a coil 31.

The driven rollers i3, l 9, 29 and 36 are identical in construction and, as shown in Fig. 3, each comprises a lower roller 38 journaled in fixed bearing blocks 59 supported by a suitable frame 49; an adjustable upper roller 4| journaled in bearing blocks l2 vertically slidably mounted in the frame id and carrying compression springs 43; vertically adjustable sliding blocks 44 slidably mounted in the frame M and engaging the upper ends of the coiled springs; and adjusting screws 45 for vertically adjusting the position of the sliding blocks so that the springs 43 will tightly and resiliently hold the upper roller in engagement with the lower roller. Both the upper and lower rollers are preferably made of resilient composition material and may be covered with asbestos or the like.

The driven rollers l3 and l9 are driven through suitable gearing such as a shaft having gears 31 and 5S fixed thereto and adapted to engage and drive suitable gears and 5!) on the roller shafts of the fixed roller of each pair of driven rollers 53 and 59, respectively. The shaft 46 is rotated by a constant speed motor 5! through suitable reduction gearing 52.

The driven rollers 29 and 36 are driven at constant speed by motors 53 and 54 through suitable reduction gearing 55, 56 connected to the lower rollers of the respective pairs of driven rollers.

The sag control devices 23 and 35 are identical in construction and, as shown in Fig. 4, each comprises an idle roller 5? journaled between the outer ends of arms 58, 59 pivotally mounted on suitable frames The rollers 57 ride freely on the upper surface of the moving sheet and are of SllfTiCli-llflt weight to hold the sheet taut against the upper surfaces of the arches in the respective furnaces. Added weight may be applied to the roller shafts to provide for the desired tensioning of the sheet.

Positioned above the arm 53 of the roller 5'! of the slack control device 28 is a limit switch 6| connected upon being operated to start motor 5| which operates the driven rollers l3 and I9.

Positioned below the arm 58 of the roller 51 of the slack control device 28 is a second limit switch 62, connected upon being operated to stop the motor 5|. The construction and arrangement is such that with all motors running and the sheet moving through the apparatus, any slack developed in the sheet, due to its expansion in the first firing furnace, Will cause the arm 58 carrying the roller 51 to move downwardly and engage the limit switch 62 to stop the motor 5|, thus permitting the driven rollers 29 and 35 to take up the slack. When the arm 58 moves upwardly as the slack is taken up, it will engage the limit switch SI and start the motor 5! so that the sheet will move through the first furnace along its predetermined line of travel.

The slack control device 35 operates in a similar manner to take up any slack developed due to expansion of the sheet in the second furnace. Positioned above the arm 58 carrying the idle roller 5? of the slack control device 35 is a limit switch 53 connected when operated to start motors 5i and 53, which drive the driven rollers l3, l9 and 29. Positioned below the arm 58 of the slack control device 35 is a second limit switch connected when operated to stop motors 5! and 53.

When the sheet expands, due to the tempera ture in the second firing furnace, the arm 58 engages the limit switch 64 and stops the motors 5i and 53. The motor 5 1 continues to run and take up the slack in the sheet. When the arm 58 moves upward into engagement with the limit switch 63, the motors 5! and 53 will be started again and the sheet will move through the second furnace along its predetermined line of travel. i

From the foregoing description, it will be readily seen that there has been provided novel and improved apparatus for continuously porcelain enameling thin sheet iron, including means for maintaining the sheet under sufiicient tension while being fired to prevent buckling and warping, whereby the finished product will be free of warping or areas of deformation and have a continuous glossy surface free of blemishes.

While the ground coat and cover coat of frit paste or slip has been shown as being applied by dipping, obviously, these coats may be sprayed on just before the moving sheet enters the firing chamber, if desired.

Obviously, the invention is not restricted to the particular embodiment thereof herein shown and described.

What is claimed is:

1. For use in apparatus for continuously porcelain enameling sheet iron of the class wherein a coil of 20-40 gauge sheet iron mounted on a horizontal spindle is fed by means of a plurality of horizontally spaced pairs of gripping and feeding rollers in succession through means for applying frit paste to the upper surface of the moving iron sheet and through a furnace having substantially horizontally aligned inlet and outlet openings therein, in which the frit paste is fused on the moving iron sheet; the combination with said furnace of means for preventing the moving iron sheet from buckling and warping during its passage through the furnace, including an arched support mounted in said furnace and extending between the inlet and outlet openings therein and over which the moving iron sheet is adapted to slide; and a tensioning member engaging the upper surface of said moving iron sheet for holding the sheet taut in sliding engagement with the upper surface of the arched support as it passes through the furnace, whereby the sheet will be prevented from buckling and warping due to the high heat in the furnace.

2. Apparatus as set forth in claim 1, wherein said tensioning member comprises a pivotally mounted idle tensioning roller.

ROBERT G. CALTON.

REFERENCES CITED The following references are of record in the file of this patent:

Number 6 UNITED STATES PATENTS Name Date Nuernberg July 1'7, 1934 Callinan Feb. 5, 1946 Calton Sept. 30, 1947 Francis Apr. 20, 1948 Martin May 3, 1949 Calton Aug. 30, 1949