US2291361A

US2291361A - Ferrous sheet material and method of and apparatus for hardening ferrous sheet material

Info

Publication number: US2291361A
Application number: US391617A
Authority: US
Inventors: William J Walsh
Original assignee: Inland Steel Co
Current assignee: Inland Steel Co
Priority date: 1941-05-02
Filing date: 1941-05-02
Publication date: 1942-07-28
Anticipated expiration: 1959-07-28

Description

July 28, 1942. w; J. WALSH 2,291,361

FERROUS SHEET MATERIAL AND METHOD OF- AND APPARATUS FOR HARDENING FERROUS SHEET MATERIAL Filed May 2, 1941 Patented July 28, 1942 FERROUS SHEET MATERIAL AND METHOD OF AND APPARATUS FOR HARDENIING FERROUS SHEET MATERIAL William J. Walsh, Chicago, 111., assignor to Inland Steel Company, Chicago, 111., a corporation of Delaware Application May 2, 1941, Serial No. 391,617

21 Claims.

My invention relates to novel ferrous sheet material and to a novel method of, and apparatus for, hardening ferrous sheet material in general but more particularly, though not exclusively, to the hardening of ferrous sheet material in the form of steel and of relatively light gage, as for example of about 25 gage or lighter, to be used in the manufacture of articles requiring that the sheet material be formed to shape, as for example in the manufacture of containers, metal coated or not, as for example by tin or terne; the sheet material requiring a surface hardening or tempering to render it sufficiently rigid or stiff to prevent fiuting and stretcher strains in forming the material to shape; this surface hardening being commonly produced by subjecting the sheet material to a skin rolling operation which, in the case of sheet material to be coated with molten metal to plate it, as for example tin or terne, should effect such an amount of reduction by the skin rolling as to insure the retention in the finished coated sheet material, after subjection to the temperature used in the applying of the metal coating to the sheet material, of sufficient temper to avoid fluting or stretcher strains as above referred to.

My objects generally stated are to provide improvements in the hardening of ferrous sheet material by which the cost of producing sheets of the desired degree of hardness or temper, may be greatly reduced; to provide for the production of sheet material having the desired degree of flatness; and other objects as will be manifest from the following description.

Referring to the accompanying drawing:

Figure 1 is a view in side elevation, in the nature of a diagram, of an apparatus embodying my invention and suitable for practicing my improved method and producing my novel material.

Figure 2 is a similar view showing the sheetbending means of Fig. 1, by which the sheet material is caused to become hardened, in open position for receiving the sheet material to be.

operated on.

Figure 3 is a similar, enlarged view of the sheet-bending means of Fig. l; certain portions of the apparatus shown in Fig. 4 being omitted in Figs. 1, 2 and 3 to avoid confusion.

Figure 4 is an enlarged transverse sectional view taken through the sheet-bending means, the section being taken at the line 4 on Fig. 3 and viewed in the direction of the arrow; and

Figure 5, a view like Fig. 1 of a modification 55 of the apparatus shown therein and also suitable for practicing my improved method and producing my novel material. I

Referring to the apparatus shown in Figs. 1-4, inclusive, Ill represents a single passskin mill shown as of the well known 4-high roll type the work rolls of which, shown at II, are backed by relatively large backing rolls I2.

Shown as located in advance of the skin mill II] are means I3 for bending the sheet material I4 to be operated on to produce hardening and flattening of the material, which may be supplied in coil form to the apparatus, any suitable means for rotatably supporting the coil to permit it to unwind therefrom being provided.

The means I3 in the form shown, comprise a pair of parallel idler rolls I5 and I6 either smooth or rough surfaced, disposed crosswise of the path through which the sheet material I4 is to travel through the apparatus, the rolls I5 and I6 being shown as backed by larger rolls I1 and I8 for preventing deflection of the rolls I5 and I6 under the stress to which they are subjected in the sheet-bending operation hereinafter described. The pair of rolls I5 and I1 and the pair of rolls I6 and I8 are relatively adjustable toward and away from each. other in any suitable way, to vary the spacing of the rolls I5 and I6 between which, when in open position as shown in Fig. 2, the sheet material I4 is forced by the operator into looped condition as shown at I9 in this figure.

The apparatus shown also comprises a stiff rod 20, as for example of steel, which the operator inserts endwise into the loop I9 of Fig. 2, this rod serving when the pairs of rolls l5 and I1, and I6 and I8 are relatively adjusted toward each other into close relationship, as for example as shown in Figs. 1 and 2, to prevent the loop I9 from becoming withdrawn from between the rolls I5 and I6 and effect the bending of successive portions of the sheet material I4 at this point in the travel of the sheet material through the apparatus.

Adjacent, and above, the rolls I1 and I8 are rolls 2| and 22 over which the sheet material I4 passes in its travel through the apparatus, the rolls 2| and 22 being provided to maintain the sheet material out of contact with the rolls I1 and I8.

As will be understood, the initial pull on the sheet material exerted by the feed means therefor and which may be the skin mill itself, causes the loop I9 to be drawn from the relatively greatly expanded condition shown in Fig. 2, into the closely contracted position shown in Figs. 1 and 3, thereby causing the sheet material to become taut about the rolls l5 and I6 and the rod 20. Thus as the sheet material feeds lengthwise between the rolls l5 and I6 and over the rod (the rolls and rod rotating in this movement of the sheet material and the portions of the sheet material above the rod 20 being out of contact with each other) the sheet material is caused to become transversely bent or deformed about the rolls and rod, sharp bending occurring at successive portions of the sheet material as it travels over this rod. Thus each succeeding portion of the sheet material M in passing around the rod is caused to be bent sharply transversely thereof in one direction and is restored to its substantially straight condition (but flatter than it was when it entered the bending means l3) in moving beyond the sheet-bending means, it having been demonstrated in practice that by subjecting the sheet material to such bending action it becomes stretched resulting in the hardening or tempering thereof. Any tendency of the rod 20 to travel lengthwise during the travel of the sheet material through the apparatus may be overcome by any suitable means as for example by providing spaced apart posts 20a oposing the ends of the rod.

As a specific example of procedure and proportions of parts of the apparatus within my invention the following may be cited, but without any intention of limiting the invention thereto:

Hot rolled strip material, such as for example steel of the composition commonly used in the making of tin-plate, from which the finished sheets are to be produced, as for example to be plated with molten tin or terne to produce plated sheets, is cold reduced from the hot, band size at least about50% on a tandem mill in accordance with common practice, to about gage or lighter, as desired, the sheet material in this operation being rolled into relatively long, wide strip-sheet form. The material thus rolled is' wound into a coil, then cleansed in uncoiled condition, in accordance with common practice,

and then again coiled and in coil form subjected to an annealing operation, preferably thorough,

as will be understood by those skilled in the art and in accordance with the common practice of making tin-plate, namely, subjected to such heat and for such length of time as to cause all portions of the sheet material to become completely annealed and render the material of maximum softness throughout. The annealed material is then passed in uncoiled, but in strip sheet condition, through the apparatus shown in Figs. 1-4 and above described, to cause it to become hardened and flattened, in such operation becoming somewhat reduced in thickness by elongation, receiving its slight final hardening by a slight reduction in the smooth roll skin mill, the hardening or tempering of the sheet thus produced being of such degree as to insure the retention in the finished metal coated sheet material after subjection to the temperature used in the applying of the metal coating, of suflicient temper to avoid fluting or stretcher strains as above referred to.

The sheet material is then cut into the desired sheet lengths; pickled as by sulfuric acid in accordance with common practice; and then coated with the desired metal, as for example, molten tin, to form tin-plate, in accordance with common practice.

As an example of the proportioning of the or temper as in the case of tin-plate as most commonly provided and requiring about a 5% reduction of the sheet material after annealing, in which case the sheet material would be rolled to about .0107 inch thickness in the cold mill, the rolls l5 and I6 may be about 5 inches in diameter and the rod 20 about inch in diameter.

Sheet materialsubjected to the procedure and with the apparatus as above described (employing the rod 20 of about inch diameter) is stressed by the action of the sheet-bending means to the point of developing minutely spaced minute substantially parallel surface fractures extending transversely of the sheet material, these fractures because of their mlnuteness being almost imperceptible and so minutely spaced apart that in the bending of the finished sheet material to shape, as for example to form can bodies, any deviation from true circular form of the shaped body, is imperceptible. I

In those cases where it is desired that the sheet I material be hardened or tempered to a less degree than in the specific example above given, the rod 20 would be. provided-of a larger diameter than about A; inch depending on the degree of hardness or temper desired to be produced in the sheet material, the larger the diameter of the rod 20 the less the elongation of the sheet material and thus the less resultant hardness or temper in the sheet material and the greater the spacing of the fractures produced in the sheetbending operation. Experiments show that sheet material. in which the fractures are spaced apart more than present a. degree of hardness insufiicient to be of practical utility.

While apparatus of the construction above described has been found to operate very satis factorily for the hardening and flattening of ferrous sheet material and is preferred to be used for this purpose, the invention is not limited thereto as the hardening and flattening of the sheet material employing the sheet-bending principle resulting in surface fracturing the sheet material, may be effected by the use of other apparatus, such as for example that shown in Fig. 5.

The apparatus in accordance with Fig. 5 operates to bend successive portions of the sheet material transversely thereof by pulling the sheet material across a stationary straight edge which causes the sheet material to sharply bend at such straight edge at successive portions of the material as it is pulled across the straight edge.

This apparatus in the form shown comprises a stationary straight edge 23 beyond and below which is a roll 24 and beyond this roll a skin mill 25 which may be of the same construction as the skin mill I0.

The sheet material M to be operated on and which may be supplied in coil form to the apparatus, is threaded over the straight edge 23 and under the roll 24 and through the work rolls of the skin mill 25. I

The straight edge 23, the coil of sheet material l4 and the roll 24 are so relatively disposed as shown that in pulling the sheet material throughthe apparatus successive portions thereof are caused to be transversely sharply bent at the straight edges 23, resulting in the hardening and flattening of the sheet material in being dragged across this straight edge; the sheet material being so stressed in the sheetbending operation referred to as to produce minute substantially parallel transverse fractures spaced apart.

The degree of hardness or temper and the closeness of spacing of the minute fractures produced in the sheet material depends on the degree to which the portions of the sheet material at opposite sides of the straight edge 23 diverge; any suitable means being provided for varying this degree as desired, as for example by adjust ably mounting the roll 24 for adjustable setting further from, or closer to, the straight edge 23, the less the divergence between said portions of the sheet material, the harder the resultant sheet material and the closer the fractures to each other even to the degree of being minutely spaced apart.

The use of a skin mill in the structures shown gives to the finished sheet material the desired surface appearance, as for example in the cases of black plate and tin-plate orterne, either a smooth or dull finish, as desired, in the latter case the work rolls of the skin mill being rough surfaced.

As will be understood, the gage to which the sheet material should be rolled for subjection to the sheet-bending operation in producing a finished sheet of the desired gage, will depend on the degree to which the sheet material is elongated in the sheet-bending operation, this being dependent on the diameter of the rod 20, in the case of the aparatus of Figs. 1-4 and the angle of divergence of the portions of the sheet material at opposite sides of the straight edge 23 in the case of the apparatus of Fig. 5, and also the degree of elongation produced by the skin mill when used, and thus the sheet material should be rolled to a gage substantially equal to the gage desired of the finished sheet material plus the amount of reduction produced by the sheet-bending operation when not followed by a skin rolling operation, or the sum of the reductions produced by the sheet bending operation and the skin rolling operation when the sheet-bending operation is followed by a skin rolling operation.

Furthermore, it Will be understood that, inasmuch as the skin rolling operation, when employed, produces elongation of the sheet material, the degree of such elongation should be taken into account in determining the sum total of the elongation to be produced in the sheet material for producing the desired degree of hardness of the sheet material, and the roll 20 be provided of such diameter in the case of the aparatus shown in Figs. 1-4, or the portions of the sheet material at opposite sides of the straight edge 23 in the case of the apparatus shown in Fig. 5 be rendered divergent at such an angle, that the elongation produced in the sheet-bending operation plus the elongation produced by the skin rolling operation will equal the total amount of the elongation of the sheet material desired to be produced.

The character of surface imparted to the sheet material by a sheet-bending operation within my invention, whereby the sheet material is fractured as described, renders the sheet material particularly adapted, when the skin rolling operation is omitted, to its use in many situations where such a surface is desirable as for example Where it is desired that the sheet material be painted or lacquered, lithographed or lead-coated.

While I have illustrated and described certain particular constructions of apparatus embodying my invention and have described my improved method as practiced by certain forms of apparatus, I do not wish to be understood as intending to limit my invention thereto as the apparatuses shown may be variously modified and altered and provided in other forms, and my novel method variously modified and altered and practiced by various modifications and alterations of the apparatuses illustrated and described and by other forms of apparatus, without departing from the spirit of my invention.

What I claim as new,and desire to secure by Letters Patent, is: v

1. The method of hardening ferrous sheet material which comprises bending successive portions of thesheet material transversely sufliciently to so stress the sheet material as to surface-fracture it.

2. The method of hardening ferrous sheet material which comprises sharply bending successive portions of the sheet material transversely sufficiently to so stress the sheet material as to surface-fracture it.

3. The method of hardening ferrous sheet material which comprises bending success ve portions of the sheet material transversely sufficiently to so stress the sheet material as to surface-fracture it and thereafter skin rolling the sheet material. I

4. The method of hardening ferrous sheet material which comprises bending successive portions of the sheet material transversely sufliciently to produce minute transverse surface fractures in the sheet material.

5. The method of hardening ferrous sheet material which comprises bending successive portions of the sheet material transversely sufficiently to produceminutely spaced minute transverse surface fractures in the sheet material.

6. The method of hardening ferrous sheet material which comprises bending successive portions of the sheet material transversely sufficiently to produce minute transverse surface fractures in the sheet material and thereafter skin rolling the sheet material.

7. The method of hardening ferrous sheetmaterial which comprises looping the material between spaced apart members, lengthwise feeding the sheet material between the members and maintaining the sheet in looped condition between the members while permitting travel of the sheet material, the looping being sufficient to cause the sheet material in its travel to be so stressed transversely as to surface fracture it 8. The method of hardening ferrous sheet material which comprises dragging the sheet material over a straight edge in such direction relative to the plane of the sheet material as to produce a succession of such relatively sharp transverse deflections of the sheet material at said straight edges as to produce surface fracturing of the sheet material.

9. An apparatus for hardening ferrous sheet material comprising spaced apart members between which the sheet material is transversely looped, a sheet-bending element disposed within the loop in the sheet material and restrainthe withdrawal of the loop from between said members, means for pulling the sheet material lengthwise in engagement with said members and element, said sheet-bending element being of such cross-sectional area as to cause the sheet material in its travel to be so stressed transversely as to surface fracture it, and a skin millfor skin rolling the sheet material.

11. An apparatus for hardening ferrous sheet material comprising spaced apart rolls between which the sheet material is transversely looped, a sheet-bending element disposed within the loop in the sheet material and restraining the withdrawal of the loop from between said members, and means for pulling the sheet material lengthwise in engagement with said members and element, said sheet-bending element being of such cross sectional area as to cause the sheet material in its travel to be so stressed transversely as to surface fracture it.

12. An apparatus for hardening ferrous sheet material comprising spaced apart members between which the sheet material is transversely looped, a rod disposed within the loop in the sheet material and restraining the withdrawal of the loop from between said members, and means for pulling the strip material lengthwise in engagement withsaid membersandrod.

13. An apparatus for hardening ferrous sheet material comprising means for feeding the sheet material, and means for bending the sheet material transversely at successive portions thereof in the feeding of the sheet material sufficiently to surface-fracture the sheet material.

14. An apparatus for hardening ferrous sheet material comprising a straight edge for engagement with sheet material fed across it, and means for pulling the sheet material across said straight edge in a direction to produce deflection of successive portions of the sheet material at said straight edge sufiiciently to surface-fracture the sheet material. I p

15. An apparatus for hardening ferrous sheet material comprising a straight edge for engages ment with sheet material fed across it, means for pulling thesheet material across said straight edge in a direction to produce deflection of successive portions of the sheet material at said straight edge suiiiciently to surface-fracture the sheet material, and a skin mill for skin rolling the sheet material.

, 16. Ferrous sheet material which is the product of the method of claim 1.

1'7. Ferrous sheet material which is the product of the method "of claim 6. r

18. Hardened ferrous sheet material having substantially parallel surface .fractures spaced apart substantially uniformly overthe surface.

19. Hardened ferrous sheet material having substantially parallel surface fractures closely spaced apart substantially uniformly over the surface.

20. An apparatus for hardening ferrous sheet material comprising spaced apart members between which the sheet material is transversely looped, a sheet-bending roller element disposed within the loop in the sheet-material and restraining the withdrawal of the loop from between said members, and means forpulling the sheet material lengthwise in engagement with said members and element, said sheet-bending element being of such cross sectional area as to cause the sheet material in its travel to be so stressed transversely as .to surface fracture it.

21. An apparatus for hardening ferrous sheet material comprising spacedapart rolls between which the sheet material is transversely looped, a sheet-bending roller element disposed within the loop in the sheet material and restraining the withdrawal of the loop from between said members, and means for pulling the sheet material lengthwise in engagement with said members and element, said sheet-bending element being of such cross sectional area as to cause the sheet material in its travel to be so stressed transversely as to surface fracture it.

WILLIAM J. WALSH.