US1608910A - Method of and apparatus for leveling sheet metal - Google Patents

Description

Nov. 30 1926. 1,608,910

C.G.L.SJ6LANDER METHOD OF AND APPARATUS FOR LEVELING SHEET METAL Filed Nov. 22, 1924 Patented Nov. 30, 1926.

UNITED STATES CARL GUSTAF LEONARD SJbLANDER, OF GOTTENBOBG, SWEDEN.

METHOD OF AND APPARATUS FOR LEVELING SHEET METAL.

Application filedgTovember 22,1924, Serial No. 751,645, and in Sweden December 6; 1922.

For leveling sheet-metal one generally uses machines with a system of rollers which bend the sheet two or more times in different directions and then straighten it in order to remove surface strains and buckles. The said method acts in a rather satisfactory manner on thick sheet-metal and such of a comparatively small breadth, but by the treatment of sheet-metal having a thickness of up to 2 mm. and when the same is very broad as for instance 1.5 m. the large buckles only are removed by the said method. Not only small buckles but also most, of the surface strains are still remaining and, consequently, the sheet becomes what is called waving. This unfavorable result is also caused by the rollers deflection or getting warped caused by the pressure during the straightening operation. Now experience has proved that the thinner the sheet is the smaller must be the diameter of the rollers but, obviously, they will deflect so much the more. Thrust rollers have been employed to prevent such deflection, but in such an arrangement the straightening rollers are subjected to considerable wear, since the contact surface between the straightening rollers and the supporting rollers is relatively small. Further, the mechanism becomes complicatedand the maintenance of same On account of the imperfect" expensive. straightening of the sheet it must be subjected to a subsequent straightening by a hammer either manually or by a machine, which in both cases is very time-wasting and requires mucli professional skill.

The present invention has for its object to overcome the said inconveniences, and according to same the straightening operation is effected in such a manner that, by means of a suitable tool movable towards and away from the sheet and past which the sheet is parallel;

being fed, the same is curved into a series of undulations extending almost perpendicularly to the feed direction of the sheet and the height of same decreasing successively until they disappear. Thus, buckles and irregular undulations of thesheet are initially transferred into regular waves whereby the strains in the sheet become more regular or During the continued operation the waves are gradually lessened in height,

until they entirely disappear. The tool must work with great speed,'but the feeding of the sheet which of course is made by steps may proceed by very short steps. In this manner the sheet will be subjected to a kind of kneading and not even the least unit of area will be left unaffected.

The accompanying drawing shows diagrammatically an apparatus suitable for the execution-of the above described method.

The tool comprises essentially two parts 1 and 2, the sheet being fed between them in the direction of the arrow by means of rollers 16 or another suitable device. Of said parts the one is movable towards and away from the other. Both parts are provided with crests 3 to 15 and grooves respectively, located in such a manner that the crests of one part correspond to the grooves of the other part. Considering from the entrance side of the tool the crests are at first of decreasing height and mounted with decreasing mutual distances between them, and thereafter they are equally high and with increasing distances between them in thefeed direction. I

Considered in the feed direction of the sheet the crests 3, 4, 5, 6 have decreasing height and decreasing mutual distances,

transfer the buckles and undulations into regular waves, then, as the distance and the height decrease, the sheet will be treated more in detail, and finally when there is no difference in height of crests the impressed undulations are brought to disappear, provi'ded that the tool is properly adjusted-referring to the drawing, so adjusted that the crests 6, 13, 7 slightly strike the opposite surfaces of the leveled sheet, whereupon the sheet passes straight between the remaining crests 14, 8, 15 which. merely execute a slight pressure on the sheet.

The increasing mutual distances of the crests 6, 7 8 and 12, 13, 14', 15 has the purpose of makingthe adjustment of the tool The last mentioned crests may caused by the tool will not exactly corre;

elasticity of the sheet-metal.

easier and to neutralize the effects of small differences of thickness which may occur in the sheet.

The said neutralizing is partly due to the Because of this elasticity the deformation of the sheet remaining height of the bends each time being diminished dueto the increasing distances between the crests and to the elastic-- ity of the sheet-metal. At a certain point the elasticity will have neutralized the undesired bends caused by the increased thickness of the sheet. In this way the tool adjustment will be less critical with a greater number of tool crests with equal height and with gradually increasing mutual distances than with fewer crests of this kind.

In general the number of crests, their heights and mutual distances have to be chosen to suit the thickness of the sheet to be leveled. Experience has proven that the thinner the sheet is the more severe must be the treatment in order to remove the original buckles and. strains. Therefore it will be suitable to provide a tool for leveling thin sheets with a greater plurality of crests and arrange them closer together than by a tool fpr thicker sheets, not precluding that different thicknesses within certain limits may be treated using one and the same tool.

The tool has to be mounted in. a suitable press which may work with great speed for example two hundred to five hundred strokes a minute or, it may be, with still greater speed, in order to make this'method most economical. As the movable tool part need not move mbre than 1.5 to 4 mm. towards and away from the other part the speed of the mac ine may be considerably raised.

The feeding of the sheet has to take place during that period of'the stroke when the movable part of the tool is withdrawn a little distance from the other part thereby letting the sheet free. The sheet is moved forward one step to each stroke of the press,

and the length of the step may not be greater than 1 to 3 times the thickness of the sheet, as the tool otherwise will leave undulations in the sheet, assuredly only some hundredth or some hundredths mm. high. Presuming the press to make 500 strokes a minute and the feed to be 2 mm. a stroke, the

feeding speed will make 1 m. a minute or 60 m. an hour, which proves that the straightening operation proceeds very rapidly.

Having now described my invention, what I claim as new and .desire to secure by Letters Patent is v 1. A method of leveling sheet metal consisting in feeding a sheet of metal in a substantially straight line, intermittently ex.- erting pressure on the opposite sides of the sheets to form a series of undulations, suc cessively decreasing the height and length of the undulations in the direction of feed of the metal sheet, and finally exerting pres sure'on the sheet to flatten out and eliminate the undulations.

2. An apparatus for leveling sheet metal comprising sheet feeding means, two cooperating parts each having a plurality of crests and grooves, the crests of one part corresponding with and opposing the grooves of the other part and adapted, upon reciprocation of said parts to form undulations in a sheet of metal interposed therebetween, the distance between the crests and the distance of the crests of each part from the fed sheet decreasing in the direction of feed of the sheet metal, said cooperating parts also having opposing portions equidistant from the fed sheet adapted to press out the undulations in the metal sheet and flatten the latter.

In witness whereof, I have hereunto signed my name.

CARL GUSTAF LEONARD SJtlLANDI-IR.

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