US2333936A - Uniformly surfacing flat metal bodies - Google Patents

Description

Nov. 9, 1943. JOHNSON 2,333,936

UNIFORMLY SURFACING FLAT METAL BODIES Filed March 28, 1942 I 2 Sheets-Sheet l f H ---i: J4 I; A "iii 1 'AAdFd k 1 J JEII F4 V f/ 1-9:: 1L

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Patented Nov. 9, 1943 UNITED STATES PATENT OFFICE UNIFORMLY svnmcmc FLAT METAL BODIES Raymond Johnson, Westmoreland. County, Pa.. assignor to Carnegie-Illinois Steel Corporation. a corporation of New Jersey Application March 28, 1942, Serial N 0. 436,693

11 Claims.

finish presents an absolutely uniform appearnace into which steam was admitted until the desired uniformity of color was produced.

Gradually there ensued a technical transition from hot rolled products to cold rolled products, but it was found that this same practice, when applied to cold rolled sheets, did notaflord the acquisition of a uniform blue oxide coating due to the inherent flatness and high surface finish of the cold rolled sheets, which caused the adjacent surfaces of the sheets in a stack intimately to engage, and thus to exclude the active oxidizing atmosphere.

It is the primary object of the present invention to teach a method for pretreating cold reduced sheets preparatory to a surface treatment thereof in stacks, such as a steam bluing operation. In a preferred embodiment of the invention, such sheets are singly passed through a corrugating or crimping device to impart a gentle undulation to the surface thereof so that when they are stacked together, the undulations do not nest but maintain the sheets in spaced relationship throughout the major portion of their surface areas. This allows for the inter-penetration of the active atmosphere during the annealing or Surfacing heat treatment.

In the accompanying drawings, Figure 1 is a front view illustrating one form of crimping apparatus adapted to the practice of the present invention.

Figure 2 is a side elevational view of the ap paratus shown in Figure 1.

Figure 3 is a perspective view of a stack of sheets shown'in exploded relationship to illustrate the material before treatment by this method.

Figure 4 is representative of a stack of sheets after passing through the crimper.

Figure 5 is a schematic plan view, showing the manner in which the sheets are advanced into and through the crimper preparatory to stacking. I

Figure 6 represents, in plan view, one method of stacking sheets in accordance with the present invention.

Figure 7 is an elevational view of the end of the pack shown in Figure 6.

Figure 8 is a view corresponding to Figure 7 after the pack has been passed through the crimping rolls.

Figure 9 is a view similar to Figures 7 and 8 showing the sheets repacked for the steam bluing operation.

Referring more particularly to thedrawings, the device illustrated in Figures 1 and 2 comprises a roll stand I having a pair of crimping rolls 2 and 3 Journaled therein in bearings 4 and 5, respectively. The lower roll 3 is arranged for revolution about a fixed axis by virtue of its bearings 5 being rigidly retained in the roll stand I. The upper roll 2 is adapted to be raised and lowered in relation to the bottom roll, which is accomplished by its bearings 4 being vertically adjustable in the roll stand I by a screw-down device 6 actingln opposition to a leaf spring I interposed between the upper bearings 4 and the lower bearings 5 of the rolls. From this arrangement it will be understood that the rolls are opened by backing-off the screw-down 8 to allow the leaf spring 1 to lift the bearings 4 in relation to the bearings 5. The rolls are closed by actuating the screw-downs in an opposite direction to urgethe upper bearings 4 toward the lower bearings 5 against the tension of the spring 1. Any suitable arrangement is, of course, permissible to achieve this end.

The crimping rolls are preferably driven. through an extension 8 of one of the necks of the lower roll 3, by a motor 9 and'a reduction gear III, which latter is connected to the roll neck extension 8 by a drive coupling l I. Suitable motor controls are conveniently placed as at I2 to vary the operating speed of the motor, thus to adjust the effective speed of the rolls to the desired value.

The crimping rolls. 2 and 3 are designed to impart a very gradual reverse curvature to the sheets so as to avoid sharp bends or any deformation that would tend permanently to mark the sheets, since the amount of offset need be but very slight to afford optimum bluing conditions as will presently appear. It is preferred that the vertical offset of the rolls be not greater than /44" from hollow to crown and the distance between crowns be sufiiciently great, such as in the order of five or six inches, to provide a very gradual curvature.

Sheet material corresponding to that shown in Figure 3 is advanced through the crimping mechanism in the manner shown in Figure 5. The sheets S are advanced through the crimping rolls, either singly or in piles, preferably in av direction agreeing with their longitudinal axes.

As illustrated in this figure, they are introduced uniformly to coat both surfaces ofeach sheet.

irrespective of its position in the pack.

Where the sheets are passed through the crimping rolls in stacked relation, such as is desirable on gauges less than 24 gauge, a preferred arrangement for conducting this operation is shown in Figures 6 to 9 inclusive. Two or more sheets, represented in these figures 81 So, So, S4,-

and 81, are stacked with their end marginal portions in substantial alignment and with their side marginal portions relatively displaced sidewise so as to dispose the sheets in slightly offset relation, as indicated in Figures 6 and 7. Such.

a pack is introducedto the crimping rolls endwise so as to dispose the crimps longitudinally of the sheets. The result of this operation is illustrated in Figure 8 in which the sheets are treated as above described, are placed in an annealing receptacle and heated to the desired temperature which will be relatively high if it is desired to anneal the sheets, but which need not exceed 1000 F. if it is intended only to blue the sheets. The bluing operation is usually conducted approximately at 900 F. Thus, if the sheets have been annealed at 1200 to 1300 F., it will be necessary to allowthe charge to cool to around 900? F. before introducing steam into the annealingfurnace for effecting the bluing op ration. Whether incident to an anneal or not, steam is introduced into the annealing container at the prescribed temperature and bathes the interior and exterior surfaces of the pack for the attainment of the blue oxide finish in a highly uniform manner.

The sheetsare thereafter cooled and removed from the annealing receptacle, and may then be given one or two passes on a cold reduction mill depending on the temper and luster desired, or

desideratum here, therefore, is that the crimps extend in the direction of rolling, since they are shown in oil-set nesting relationship. The sheets are then slid sideways, relative to each other until their side margins are in substantial alignment, as shown in Figure 9. This obviously dis- I ruptsthe nesting relationship of the crimps and.

provides a pack of the desired openness.

As has been said, the extent of the offset provided by the crimping should bev of a relatively slight order, preferably not to exceed /4'. and for optimum results, in the order of In this more easily obliterated by a subsequent pass or two on a cold mill when disposed in thismanner. Another reason for this practice is to dispose the crimping in that direction in which the least number of crowns are impressed into the materials By disposing the crimps longitudinally of eachsheet, the numbero'f crowns thus'realized is necessarily less, by virtue of being applied across a lesser dimension of the sheet, than would be the connection, it has been found that, where an exceedingly open pack is provided by crimps of greater magnitude, such as would be represented by commercial corrugating practice, the oxidizing .action thus allowed is so severe as to build up a heavy gray oxide throughout the more exposed areas of the sheets in the pack. Such a gray oxide not only presents a non-uniform contrast to the blued areas of the more sheltered portions of the sheets, but is so brittle as to be completely cracked-off during the succeeding leveling operation so as to defeat the intended purpose. The gentle undulations or crimps, herein contemplated, afford no more than the optimum openness of pack, thus to insure of the acquisi- Q tion of a uniform oxide blue coating throughout both surfaces of each sheet. therefore, that in addition to providing an open pack for inter-penetration of an oxidizing gas,

It will be seen,

inter-penetration of an active case were they to be applied crosswise of the sheet, and, thus, extend down its greatest dimension. Any slight marking that might result from the crim ing operation is, because of this, minimized bi the preferred practice.

Obvio sly the extentof the crimping illustrated in Figure 4 has been greatly exaggerated for purposes of illustration. Actually'the amount of offset provided by this crimpingneed be very slight in orderto be effective in allowing the atmosphere through a stack of sheets as here contemplated.

Since the apparatus and method for giving 'efl'ect to the novel relationships herein disclosed may assume a variety of forms, it is intended that the herein disclosed embodiment ,be regarded as illustrative rather than restrictive. Therefore. it is not intended that the present invention be limited thereby other than as is necessitated by the recitation of the appended claims.

I claim:

1. The method of treating metal sheets in stacks to insure inter-penetration of the atmosphere surrounding the stack, which includes the step of plastically deforming each of the sheets throughout its cross-section so as to impart an undulatory characteristic to each sheet to disrupt the planar disposition of its surfaces, stacking said sheets so that corresponding undulations on adjacent sheetsareout of registry to avoid nest- 2. The method of steam bluing steel sheets which includes imparting a wavy characteristic thereto preparatory to stacking, stacking such sheets in a manner to avoid nesting thereof, heating said sheets in an enclosure, and admitting steam into said enclosure to impart a blue oxide film uniformly over both surfaces of each sheet.

3. The method of steam bluing steel sheets which includes imparting a wavy characteristic thereto preparatory to stacking, stacking the wavy sheets to avoid nesting thereof, heating said sheets in an enclosure, and while heated, bathing them in steam by introducing steam into the enclosure to impart a blue oxide film to each surface of the several sheets, removing the sheets from said enclosure, and working said sheets to impart flatness, temper and luster.

4. The method of steam bluing steel sheets which includes crimping each sheet preparatory to stacking, stacking said sheets to avoid the nesting thereof, heating said sheets in an enclosure, and, while at a temperature between 800? and 1000 F., introducing steam into said enclosure to blue the sheets, removing the sheets, and working each one to flatten and impart the requisite temper and finish thereto.

5. The method of steam bluing steel sheets which includes lightly crimping a plurality of such sheets, stacking said sheets with the crimps thereof in opposition to avoid nesting, enclosing said sheets in an annealing enclosure, annealing in stacks by an oxidizing atmosphere at elevated temperature, the improvement which includes, as a preparatory step, cold straining said sheets to warp them out of a planar disposition, and stacking said sheets in non-nesting relationship to provide an open pack.

8. In the art of uniformly bluing cold reduced steel sheets in stacks by an oxidizing atmosphere incident to an annealing thereof, the improvement which includes passing each sheet through corrugating rollers lightly to corrugate it so that the corrugations fall in different places in relation to the marginal portions of each sheet, stacking the sheets in congruent relation to provide an open pack, annealing said sheets, and, while within the annealing furnace, bathing the pack in steam introduced into the furnace, cooling the sheets to room temperature, and cold working each sheet to impart flatness, finish and temper.

9. In the art of bluing cold reduced steel sheets in stacks by an oxidizing atmosphere at elevated temperature, th improvement which includes, as a preparatory step, cold straining said sheets to warp them out of a planar disposition in a recurrent offset pattern, the extent of the offset not exceeding /4", and stacking said sheets in non-nesting relationship to provide a pack of moderate openness.

10. In the art of bluing cold reduced steel vi sheets in stacks by an oxidizing atmosphere at said sheets, cooling said sheets from annealing temperature within the enclosure to a temperature between 800 to 1000 F., introducing steam into said enclosure to impart a blue oxide coloration to both surfaces of each sheet substantially uniformly, cooling said sheets to room temperature, and working said sheets to impart flatness, finish and temper.

6. The method of steam bluing steel sheets that have been cold reduced to gauge, which includes lightly crimping the cold reduced sheets preparatory to stacking, stacking several of said sheets with the corresponding crimps of adjacent sheets out of registry to provide an open pack, annealing said sheets at a temperature in the neighborhood of 1100" F., cooling the stack in the furnace down to about 900 F., introducing steam into the furnace which permeates the pack and imparts a uniform blue oxide finish to both surfaces of each sheet thereof; thereafter, cold working said blued sheets to impart the desired flatness, finish, and temper thereto.

7. In the art of bluing cold reduced steel sheets elevated temperature, the improvement which includes, as a preparatory step, cold straining said sheets to crimp them in a manner to dispose the crimps so that the longitudinal axes of the latter substantially agree with the direction in which the sheet will be subsequently rolled, limiting the depth of crimp to A," or less and stacking said sheet in non-nesting relationship to provide a pack of moderate openness.

11. In the art of billing cold reducedv steel sheets in stacks by an oxidizing atmosphere at elevated temperature, the improvement which includes, as a preparatory step, stacking several sheets together with their edge portions out of substantial alignment and with their remaining portions in overlapping relationship, passing such pack endwise through crimping rolls so as to impress longitudinally extending crimps up on the pack, then re-assembling the sheets to bring their marginal portions into substantial alignment, thus to provide an open pack.

RAYMOND JOHNSON.

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