US2066085A - Methods of embossing sheet-metal - Google Patents

Description

, Dec. 29, 1936. v. WHISTLE? METHOD OF EMB OSSING SHEET METAL Filed Oct. 7, 1955 .w If 7 Ia zrrelzce fmilef Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE My invention relates to improvements in methods of embossing letters, figures and other characters or designs on sheet metal or the like, particularly such as are used on signs displayed over store fronts, or otherwise. Signs of this character are nowin use, but they are limited in number, due to the fact that they are exceedingly expensive to construct, and more particularly for the reason that they are not satisfactory, since it is an exceedingly difiicult matter to emboss letters in sheet metal of the gauge required for such signs without forming irregularities adjacent the embossed letters, which may be discribed as wrinkles and which are quite pronounced at the corners of the letters. When signs of this kind are enameled or otherwise given a gloss finish to meet the requirements for a usable sign, such irregularities or wrinkles are tremendously magnified, particularly when artificial light is directed against the same; but under all conditions,

these irregularities appear quite prominent under any light, when viewed from certain angles.

The present method of constructing embossed metallic signs calls for the use of expensive dies, and as there is an increasing demand for signs of this character, especially signs constructed of heavier sheet metal than now possible to employ in order to attain results that even approach present day requirements, dies employed under the common method of embossing are limited for use to gauges of metal which result in signs that are more or less flexible and do not have the rigidity usually demanded by users. Costly hand-cut, or at least hand-finished dies are required, and these call for male and female die-members which must be exactly matched and at least finished by hand. Although out in hardened metal, such dies require additional hardening or tempering after being finished, all of which adds to the cost of production of signs of the kind mentioned.

Inasmuch as dies now employed are limited in use to certain thicknesses of metal, new dies are required when metal of a heavier or a lighter gauge is employed, even though the signs produced by the two sets of dies were exactly alike. The life of such dies is comparatively short, due to the demand for use of heavy material; and with the employment of the most expert workmanship, the method under which they are employed necessarily results in a distortion of the metal used to form the sign after embossing the letters therein.

Under my improved method I employ an expansible fluid container, orat least a fluid chamber having a rubber or other expansible or flexible wall adapted for co-action with a rigid die-member, and between the two the sheet metal to be operated upon. is placed so thatpressure within the expansible fluid container or against the yielding wall, as the case may be, will cause the metal to conform in shape to that of the rigid die-member. It is however to be understood that substituting an expansible fluid container, or a fluid chamber or container having an expansible or flexible wall for the male member of a die, would not in itself eliminate the irregularities in signs now commonly caused by the use of steel or other rigid co-acting die-members. 1, however, employ a combination of rigid die-member and an expansible fluid container, under which term I include a chamber having an expansible or flexible wall, for the purpose ofreducing the cost of production of signs of the character mentioned, since under such a combination an inexpensive pattern can be constructed to form the desired characters or design and a mold made therefrom to cast the die in any suitable metal, for example, cast iron; thereby eliminating costly die-cutting which is necessary when steel or other hard metal male and female die-members are employed.

The primary object of my invention is to provide a method in which sheet metal is stretched into a cavity or depression formed in a rigid diemember, while immovablyretaining .those portions of the metal in a region completely surrounding the cavity or depression; thereby preventing the formation of wrinkles in the flat portion of the sheet metal within and surrounding any character or design formed by said cavity or depression in the sheet metal to conform to that of the cavity or depression in the rigid diemember. p

Another object of my invention is to provide a method of embossing sheet metal whereby metal strain set up within and around the character or the outer'edges of the strip, thereby eliminating the necessity of trimming the strip, which must of necessity be resorted .to under present-day methods, before baking or vitreously-enameling the embossed metal strip.

A still further object of my invention is to provide a method which will prevent metal-flow from the marginal portions of the sheet or strip. usually occurring in order to supply material for the embossing; thus guarding against deformation of the sheet or strip and producing an embossment in which the metal at the embossment and directly around the same is thinner than at the marginal portions of the sheet or strip.

Another object of my invention is to provide a method whereby hold-down pressure is employed around the region of the sheet or strip to be embossed, and wherein sufficient, but a lesser pressureis employed for stretching the metal in the area surrounded by the hold-down region and forcing the same against and into the portion of a die-member having letters, figures or other characters, or designs of any kind formed therein.

A further object of my invention is to provide a method whereby several letters or other characters, or designs may be formed in sheet metal by stretch-embossing the metal while immovably holding down the metal along a region completely surrounding that in which the severalcharacters or designs are to be stretch-embossed.

A still further object of my invention is to provide a method for embossing sheet metal whereby a single rigid die-member is employed in combination with a self-conformable associate member so as to enable the same rigid diemember to be employed for embossing various thicknesses of sheet metal.

A still further object of my invention is to employ a method of embossing sheet metal whereby assurance is had that no irregularities will be formed in or on the face side of the embossment requiring correction by means of tools, which invariably result in tool-marks being formed and which, although they appear imperceptible on the unfinished embossed metal, become so magnified when enameled or otherwise gloss finished as to appear very prominent.

My invention consists in a method of forming sheet-metal signs wherein hold-down means is provided around a region of a blank sheet, or strip of sheet-metal to be embossed and in effecting the embossing within this surrounded region by stretching the metal from the holddown region inwardly and reducing the thickness of the metal at the embossment and gradually to a lesser degree outwardly from the emstamping or embossing press which is particularly adapted for use in constructing metal signs and otherm'etallic embossed objects according to my improved-method.

In the drawing, Fig. l is a sectional elevation of a portion of a press particularly adapted for embossing sheet-metal signs and the like in accordance with my improved method; the ,ram carrying the self-conformable member 55001! ated with the rigid die-member being elevated and the rigid die-member having a sheet of metal placed thereon preparatory to embossing the same according to the characters or design formed in or on said die-member.

Fig. 2 is a similar view showing the ram lowered and pressure exerted to immovably hold down the sheet around the embossing region and to have caused the metal to be embossed in accordance with the single die-member employed.

Fig. 3 is an enlarged vertical section showing the upper portion of the rigid die-member, an embossed sheet of metal, and the expansible element associated ,with the die-member having caused the embossment in the sheet of metal under applied pressures.

Fig. 4 is a face view of a square of metal having a letter embossed therein; such letters being sometimes formed in square or other rectangular pieces of metal to be attached to a suitable foundation, the letters being employedin the desired combination to display a firm name or other information.

Fig. 5 is a face view of a portion of a strip of metal having a plurality of letters embossed therein.

Reference being had to the drawing in detail with a view of making clear my improved method, the numeral 6 designates the bed of a stamping and embossing press, on which a female die or die-member I is secured, this die or die-member being formed of metal, and due to the nature of this invention and the advantages gained thereby, such die or die-member may be of castiron and formed in a sand or any other mold made from a simple inexpensive wood pattern.

It has been found that a cast-iron die or diemember for this purpose can be made without resorting to the use of hand tools for finishing the cavities or depressions molded therein.

I have associated with the die-member I, a pressure element 8 which is preferably in the form of an expansible fluid container and located within a box-like structure 9 providing the necessary rigid confining or restraining walls for this expansible container. This box-like structure is secured to the ram 10 of the press, which is operated in any approved manner; only so much of a press being shown in the drawing to make clear the mode of practicing my invention.

The expansible fluid container is in the form of a rubber bag having a top wall II, a bottom wall l2, and edge or side walls l3 at the four sides thereof. The box-like structure 8 also comprises a top wall I, and edge or side walls I! at the four sides thereof, the bottom of this box-like structure being open so that the rubber bag is exposed from the bottom. The edge or top wall II and the edge walls l3 of the rubber bag are restrained against outward movement by the corresponding rigid walls of the box-like structure 9, which latter walls are of suillcient thickness and rigidity to withstand a pressure safely of four thousand pounds per square inch or more, depending on the gauge of metal to be embossed.

Water, designated by the numeral It, or any other fluid may be introduced into the expansible chamber or rubber bag, and for this purpose it has molded in one of its walls an inlet stem or tube l'l which is connected by a suitable coupling i8 with a supply pipe I! leading from a source of fluid supply of the required pressure. A portion of the supply pipe l9 may of course be made flexible so that the ram in its movement toward and from the bed of the press will not strain the joints or connections of this pipe. The fluid under pressure may however be supplied to the expansible fluid chamber in any other manner.

I desire here to state that under my method sheet-metal is what I term cold-embossed", as distinguished from methods in which the object to be embossed is subjected to the action of heat in order to render the object more or less plastic innature, and it also difiers from such methods in which the object to be embossed has been rendered elastic in order to follow the form of the matrix against which it is to be pressed.

The ram I0 is guided for movement on guiderods 20 extending upwardly from the bed of the press, and this upward movement is limited by nuts 2| threaded onto the upper ends of these rods, or in any other manner. Any other form of press may be employed, if desired, as the press illustrated is merely one of many conventional forms of presses and is shown solely for the purpose of illustrating suitable means for practicing my improved method of embossing.

It is also to be understood that since the top and edge or side walls of the expansible chamber 8, or more particularly defined, the rubber bag, are at all times in contact with the corresponding walls of the boxlike structure 9, which may be referred to as a retainer element, only the lower wall of said bag is designed for efiective movement under pressure. However, when such action takes place, the edge or side walls l3 will be stretched accordingly and restrained by the corresponding walls of the retainer element, and the lower wall will act as a hold-down for the metal against the die at all regions between the cavities formed in the latter.

It is to be noted that in Fig. 1 the expansible bag is shown as having the pressure fluid l6 therein, although it is in elevated or inactive position. At such times the fluid is relieved of pressure, or at least of the high pressure required for effecting the embossing of the sheet-metal, which for large store signs requires a pressure of fifteen hundred tons while the hold-down means is subjected to a pressure of three thousand tons. In this figure the sheet-metal, designated by the numeral 22, is placed upon the diemember I preparatory to embossing the same. In the particular die shown, a single letter or figure is formed therein, the letter or figure being outlined by a cavity or depression 23 formed in the face of the die.

In Fig. 2 the ram is shown lowered, with the result that the edges or the side walls [5 of the retainer element 9 are in contact with the sheet metal entirely around the region of the metal in which the embossment is to be made. When the ram is lowered, a pressure of many tons, oftentimes three thousand tons, is applied thereto, but the pressure thus applied is always in accordance with the area of the sheet-metal surrounded by the side walls of the retainer element 9. This pressure, when applied to the ram, I term holddown pressure for the sheet-metal. The fluid within the expansible container is then placed under the required pressure, approximately three thousand pounds per square inch, and oftentimes fifteen hundred tons, depending of course on the area to be embossed and the gauge of the sheet metal which is to be embossed. This pressure applied to the fluid within the chamber is in all instances less than the hold-down pressure, and when applied causes the portions of the sheetmetal lying over the cavity 23 to be forced thereinto, the lower wall of the expansible container following the metal and between the cavities serving as a hold-down medium, with the result that the metal is surface-stretched and reduced in thickness where it enters the cavity and probably slightly where it immediately surrounds the cavity, the stretching taking place inwardly from the side walls l5 of the chambered retainer element so that a condition exists, after the sheet metal is embossed, approaching that shown in Fig. 3. In this figure, the metal is shown gradually reduced in thickness from the vertical planes 24 to the cavity, and a similar condition exists in that portion of the metal lying between two spaced portions of the cavity; for example, the metal may be gradually reduced in thickness from the point 25 to the two cavity portions at opposite sides of this point, the greatest reduction in thickness being formed within the cavity, and at all other points such reduction is barely perceptible. For example, metal normally of .0375 gauge is reduced to .0295 where deeply embossed, to .0355 at the angles of embossment and immediately surrounding the embossment, and by actual tests made its gauge will be .0373 less than one-half inch from the angles formed at the embossment. Therefore, from this point outwardly to the surrounding hold-down means, there will be no perceptible or even measurable reduction in the thickness of the metal. It will be clear, therefore, that the opposite parallel edges of the sheet or strip of metal will be retained in parallelism, and there is absolutely no movement of the sheet-metal from the vertical planes 24 outwardly to the edges of the sheet, these portions retaining their original gauge or thickness, and practically none from such plane to within a fraction of an inch from the embossment.

While I have shown a rubber bag as the expansible fluid chamber, I include within this term any structure in which a self-conformable wall, such as the lower wall of the rubber bag 8 provides, and this self-conformable wall need not form a part of a rubber bag, since it may be a rubber or other flexible or expansible element stretched across the bottom of a fluid container, such for instance as the chamber retainer 8 may be employed for. that such flexible or expansible element would have to be associated with the other portion of the fluid container in a water-tight manner to prevent leakage. It is also to be understood that while the cost of production of metal signs or the like would be greatly reduced by the employment of a single rigid die-member associated with a flexible element self-conformable to the rigid die-member, my method could be practiced It of coursewill be understood by employing hand-cut male and female dies and associating with such dies suitable hold-down means for the sheet-metal, whereby the metal would be held against both stretching and bodily movement around the region in which the embossing is to be effected. Such a male and female die construction would, however, be exceedingly expensive, since it has been determined that the cost of producing a sign by means of such dies, without hold-down means to prevent movement or stretching of the marginal portion of the piece, sheet, or strip of metal would be at least five times that of producing a sign with the means herein shown, and would of course require trimming of the marginal portion of metal after embossing according to present-day methods in order to have opposite edges of the metal parallel.

I have shown in Fig. 4 a letter on a square piece of sheet-metal, embossed according to my improved method, and in this figure the vertical edges are absolutely parallel, and the horizontal edges are likewise parallel, as clearly shown with full lines. Embossing a square piece of metal, such as shown in Fig. 4, under present-day meth- 5 ods, results in drawing the sheet-metal from the marginal portions to supply the material for the embossment, with the result that the vertical edges in. the particular square shown in this figure would be drawn inwardly approximately as shown by dotted lines 26, while a similar but somewhat lesser inward flow of the metal would occur from the horizontal edges, with the result that these horizontal edges would be approximately as indicated by dotted lines 21 in said figure.

When embossing a strip of metal, such as might be required for a complete store sign from twelve feet upwardly in length, the old method would result in a similar curvature being formed at the ends of the strip, as shown by the dotted line 28 in Fig. 5, and an irregularity of the horizontal edges would occur also above and below the first letter in the manner illustrated by the dotted lines 21 in Fig. 4. Attempting .to .emboss 25 a second letter on the strip in properly spaced relation to the first letter, which in Fig. 5 is shown as the letter H, and the second as the letter I, distortion of the strip would occur which would increase the curvature at the end of the strip indicated by the dotted line28, and

would also result in distorting the letter H substantially as shown by dotted lines 29 in Fig. 5. An exaggerated distortion would also occur along the horizontal edges of the strip above and beneath the letter I with the result that the letter H would be out of parallelism and probably out of alinement with the letter I. However, this might result in the letter I being in true vertical position on the strip, while the letter H would become entirely distorted; not only the vertical portions of the letter H, but the horizontal or cross portion connecting the two vertical portions would be drawn out of its regular position. Assuming a third letter, such as T",

shown in Fig. 5, were to be stamped in the strip, this would result in the letter I being distorted to at least the same degree as the letter H; and due to the extended horizontal upper portion of the letter T, a marked distortion would ocour above the letter I in addition to the distortion effected above the letter H", and a decided curvature, greater than that formed above the letters H and I would be created at the upper horizontal edge of the strip above the letter "T.

The distortion of the letter I would also result in additional distortion of the letter H, because the forming of the letter "1" would also carry through the entire strip. After several of these letters have been embossed in the strip, the

0 embossing, as well as the stripl of metal, would be so distortedas to practically render the sign useless.

According to my invention, letters may be successively embossed along a metallic strip with- 5 out creating any distortion between letters, or at the edges of the strip; in fact, absolutely no distortion of the letters would occur and the letters would be sharply outlined, yertically parallel and horizontally alined, while all surrounding 70 portions, or portions within the letters would be perfectly flat and level with the marginal por-v tions of the sheet. The stretching of the material in the region being embossed while holding surrounding portions against movement or 1 stretching, eliminates the possibility of forming wrinkles in the flat surface of the sheet. Under present-day methods, not only would the sheet be distorted, as shown by dotted lines in Figs.

4 and 5, but adjoining the letters, figures, or other designs embossed, wrinkles appear in the 5 surface of the metal as though radiating from the embossment, and this is most pronounced at the corners of the letters. Signs of this kind are invariably enameled and after enameling these wrinkles appear greatly magnified. Many signs 10 are provided with overhead or with neon illumination, and when illumination of any kind is associated with the signs, these wrinkles appear so prominent as to make the sign appear as an imperfect product. However, since under pres- 1 ent-day methods it is not possible to eliminate the wrinkles, they are accepted as the best obtainable in sheet-metal enameled signs having letters either in intaglio or in relief, depending on which side of the metallic sheet is used as the 20 face of the sign. In some instances, depressed letters are called for to be used in connection with neon tubes placed within the depressions, and by means of my invention either side of the sheet-metal may be employed as the face of the 25 sign, since both the relief side of the letters or the impressed or intaglio side of the letters will be perfectly formed without wrinkles at any point thereof, and all other portions of the sign will be perfectly fiat and parallel-edged, without 30 resorting to the use of edging or straightening machines.

By stretching the metal to form the characters instead of drawing the characters, no metal strain occurs around the outer portions of the letters 35 or other characters, or design outlined, and the baking of vitreous enamel thereon will be much flatter, which is highly desirable in signs of the character mentioned. Moreover, the embossing of the letters or other matter will be in higher or bolder relief than has heretofore been possible.

I might also state that due to the inexpensive dies employed, several letters, or all of the letters, of a sign may be formed on a. single die-member and the effect of the operation under my improved 45 method would be the' same as though forming.

a single letter in the metal. It may also here be stated that under present-day methods of embossing sheet-metal, imperfections in the letters occur, which require correction by means of hand 50 work or resorting to mechanical means for eliminating the imperfections, but in suchcases tool marks are quite apparent after enameling the sign, even though they appear to have been entirely eliminated on' the unfinished surface. 55 Since no imperfections result under my improved methods, corrections are not found necessary and such tool marks are consequently not formed; which also aids in providing an inexpensive metal embossed or intaglio sign which is parallel-edged, perfectly flat, devoid of wrinkles and smooth and even throughout when enameled or otherwise gloss-finished; resulting in a sign having the apagainst movement during the act of operating thereupon, and reducing the thickness of the metal at the embossment by surface stretching.

3. The method of embossing sheet-metal, comprising retaining the region of the metal surrounding the region to be embossed against movement and cold stretching the metal in the surrounded region to effect the embossment.

4. The method of making metal signs having letters, figures, or other characters or designs in relief or intaglio which includes the application of a predetermined pressure to the metal in the region operated upon to surface-stretch the same while subjecting the surrounding portion of the metal to greater pressure to prevent movement of the metal at said surrounding portion.

'5. The method of producing embossed or intagliated characters or designs in sheet-metal which comprises the cold stretching of the metal under pressure to reduce the thickness of the same while retaining a surrounding portion of the metal against stretching and bodily movement.

6. The method of embossing sheet-metal or the like which consists in clamping the region of the metal surrounding the region to be embossed to prevent movement of the metal at said clamped region and to maintain the edges of the metal in a straight line, and in applying force to the region to be embossed sufficient to emboss the same according to a die, such force being less than that required to clamp the sheet-metal.

7. The method of embossing sheet-metal or the like which consists in clamping the region of the metal between two rigid elements and which region at least partially surrounds the region to be embossed and in applying force to the region at least so partially surrounded to emboss the same according to a die while retaining the clamped region immovable and non-stretchable.

8. The method of embossing sheet-metal or the like which consists in clamping the region of the metal between two rigid elements and which region surrounds the region to be embossed, in applying force to the region so surrounded to emboss the metal in said region according to a rigid die disposed beneath the area of the sheet-metal to be embossed, and in maintaining the clamped region immovable and non-stretchable.

9, The method of embossing sheet-metal which consists in placing the metal between two cooperating members, one of which is provided with the pattern to be embossed and the other having an expansible wall, in applying pressure against said expansible wall in the direction of said rigid die to efiect the embossment, and in clamping the sheet-metal around the region to be embossed preparatory to embossing under force greater than that applied to said expansible wall for effecting the embossment so as to maintain the edge of the metal straight-lined.

10. The method of embossing or-intagliating sheet-metal which comprises the positioning of the metal on a rigid die bearing the outline or outlines to be transferred to the metal in embossed or intaglio form, the retaining f the sheet-metal against said die under pressure applied thereto to completely surround the region to be embossed or intagliated, and the application of pressure to an expansible element bearing against the sheet-metal to cause said transfer to be made, the pressure applied to said expansible wall being less than that applied to the sheet-metal around the region to be embossed or intagliated so that movement of the metal takes place only in said region.

11. The method oi embossing or intagliating sheet metal which comprises the positioning of the sheet-metal upon a rigid die, in moving a fluid chamber having an expansible wall in contact with the sheet-metal in opposition to said die, in applying high pressure within said chamber and preparatory to the application of said pressure applying greater pressure to said sheetmetal in a region surrounding said pressure chamber so as to prevent movement of the metal in said region.

12. The method of embossing or intagliating sheet-metal, which comprises the positioning of the sheet-metal upon a die having a fixed position, in lowering a. pressure element having a flexible wall towards said die, in exerting pressure with said pressure element against the sheet-metal around the region thereof to be embossed to prevent stretching and bodily movement of the metal surrounding said region, and in applying pressure behind said flexible wall to prevent uniform stretching of the metal in such region but to allow the full limit of stretch of said metal into the lower or depressed portion or portions of said die.

13. The method of forming embossed sheetmetal signs which consists in supporting a die on the bed of a stamping press, in fastening a flexible wall to the ram of said press, in then placing the sheet-metal over said die and lowering said ram under tons of pressure to hold down said sheetmetal around the region thereof to be embossed under the pressure so applied, to apply tons of 14. The method of forming embossed sheetmetal signs which consists in supporting a die on the bed of a power press, in maintaining a flexible wall on the ram of said press, in then placing the sheet-metal over said die and lowering said ram under pressure to hold down and prevent movement of said sheet-metal around the region thereof to be embossed under the pressure so applied, to apply pressure above said flexible wall after said sheet-metal is so held down so as to cause the metal to cold-stretch and enter a cavity or cavities in said die and to act as a hold-down for said metal against said die immediately surrounding the cavity or cavities therein, in relieving said pressures and elevating said ram, in then substituting another die and moving said sheet-metal across the latter to space the same for the next embossment, and in again lowering said ram and applying said pressures to provide an embossment in accordance with said die in spaced relation to the first embossment.

15. The method of embossing sheet-metal, comprising the placement of a sheet of metal between two parts relatively movable, in bringing said parts together and subjecting the metal so placed to two different pressures, the lesser of which effects the embossment of the metal while the greater pressure is utilized to hold down the metal outside of the region of embossment and prevent movement of the metal at the region held down.

16. The method of embossing sheet-metal,

comprising the placement of a sheet of metal between two parts relatively movable, in bringing said parts together and subjecting the metal so placed to two different pressures, the lesser of which effects the embossment of the metal while thegreater pressure is utilized to hold down the metal outside oi! the region of embossment so as to maintain a straight-lined edge for said metal. 7 17. The method of embossing sheet-metal, comprising the placement of a sheet of metal between two parts relatively movable, one of said parts having a rigid die member and the other a flexible wall, in applying a predetermined pressure to the region of the metal outside of the region thereof to be embossed under relative movement of said parts so as to hold down the metal outside of said region and prevent movement thereof, and in applying the lesser pressure behind said flexible wall to effect the embossment of said metal.

18. The method of embossing sheet-metal signs,-

comprising theplacement of a sheet of metal between two relatively movable parts, in subjecting the region of the metal outside of the region thereof to be embossed to a predetermined holddown pressure under relative movement of said parts so as to prevent movement of the metal in said region, in subjecting the metalisurrounded by said hold-down region to a predetermined pressure sufilcient to emboss the metal while retaining the metal in said hold-down region against movement.

19. The method of embossing sheet-metal signs,

comprising the placement of a sheet of metal between two relatively movable parts designed to cause embossment of the metal, in subjecting the region of the metal outside of the region thereof to be embossed to a predetermined hold-down pressure under relative movement of said parts so as to prevent movement of the metal in said region, in subjecting the metal surrounded by said hold-down region to a predetermined pressure sufilcient to emboss the metal while retaining the metal in said hold-'down region against movement, in relieving the metal of pressure and moving the sheet 01' metal to position a new region of the metal between said relatively movable parts, and in repeating the procedure of holding down the sheet-metal, embossing the same and moving the sheet between said parts for each additional letter to be embossed in the sign, all

while maintaining the edges of the sheet-metal substantially straight-lined.

20. The method of embossing sheet-metal,

comprising the application of hold-down pressure against spaced hold-down areas of the metal to prevent movement of the metal in said areas and the application of a lesser pressure to embossing means effecting embossment of the metal between said hold-down areas whereby the embossment is effected by the stretching of the metal in the region only between said hold-down areas.

LAWRENCE v. WHISTLER.

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