US2169937A - Method of producing perforated metal sheets - Google Patents

Description

Aug. 15, 1939.' is. WEMRE 2,169,937

' IETHOD OF PRODUCING PERFORATED METAL SHEETS Original Filed Feb. 15 ;"195'7 wnwlmnmmvmw I mi mmn, fiernhagd'hmpe Patented Aug. 15,1939

UNITED sures PATENT orricr.

METHOD or monucmc rnaromirnn METAL snnn'rs Bernhard Wempe, Berlin-Charlottenbnrg,

Germany Original application February 15, 1937, Serial No. 125,892. Divided and this application April 20,

1938, Serial No. 203,178.

ary 20,- 1936 In Germany Febru- 8 Claims. (oi. 29-1633) forated metal wherein many minute holes maybe formed without boring the metal. Other and further features and objects of the invention will be apparent to those skilled in the art upon a consideration of the accompanying drawing and the following description wherein several exemplary embodiments of the invention are disclosed. a

In thedrawing:

Fig. 1 is a sectional view of the trough-like older illustrating a series of plates and wires arranged therein.

Fig. 2 is a sectional vi w of the metal plates showing the manner in which pressure may be applied thereto.

Fig. 3 is a sectional view of the block after fusion of the metal plates. 1

Fig. 4 'is a sectional view of the plates illustrating the mannerin which the wires may be arranged in grooves of the plates.

Fig. 5 illustrates a modification of the process by the employment of a. profile roll.

A plate of metal 5 is first arranged on a suitable support as shown in Figure 1. Above this plate of metal wires 3 are arranged in uniform parallel spaced relation. Each wire must be harder than the metal. Upon this layer of wire a fresh plate 5 of metal is positioned. This again is followed by a layer of wires 3, and thisis continued until the superposed plates of metal, with the layers of wire interposed between them, at-

tain a substantially square cross section. The 0 plates of metal preferably lie between lateral struts in -a more or less trough like holderas shown at l in Figure 1.

, Upon the uppermost plate of metal a cover (not shown) may be placed with an insulating .5 layer of asbestos paperbetween the outer cover and the. metal plate. Pressure is then exerted upon the" block of the metal plates or upon the outer cover that closes the trough. The pressure depends upon the'kind of metal employed. The

0 block is also heated and under thQlnfluence of heat and pressure the plates unite by fusion. in consequence of the pressure and of the correspondingly high temperature, a homogeneous block of metal is obtained, as shown in Figure 3.

5 After .the block of metal in the trough has been allowed to cool down to some extent it is placed in an annealing lehr, made free from stress, and then cut into sheets. In this way sheets of 'metal are obtained with a numbr of wiresembedded therein parallel to one another 5 and accurately spaced. If the wires-3 are now etched out by the'action of acid. sheets of metal of any desired thickness are obtained with accurately calibrated holes.

The operation of heating and fusing may take 10 place in a vacuum 'or inan atmosphere of hydrogen, or in an atmosphere of inert or neutral gas, as a resultof which oxidation is precluded. For instance wires of a base metal can then be used without risk. I

The process may also be modified in'the following manner:

The metal plates are pressed together under a high pressure, the pressure preferably being applied not only in one direction, that is, vertically. 20 but also at right angles thereto or in a horizontal direction as indicated by the arrows 6 and l of Fig. 2. During the pressing, however, no heating generally takes place at first. After pressing and r before heat is applied the plates are taken apart. '25

in an orderly manner and the wires,'with the exception of oneor two for each layer, such as and 3b of Fig. 4, which serve for fixing the position of the metal plates, are taken out. The

- metal plates are then superposed again in the 30 same order, their positions being fixed by the one or two wires that have been left in the plates in each layer. The block of metal plates is now exposed to a high pressure again, and at the same time is heated to a high temperature in an at- 35 mosphere of hydrogen or inert gas or in a vacuum. The degree of heat mustbe such that the fusion that now sets in proceeds with appreciable velocity, and is therefore completed under ordinary conditions in about half an hour. The 40 metal plates; are thereby united to form a completely homogeneous block'of metal, as shown in Figure 3, 'and may be taken out of the heating furnace.

To. enable the block to be cut into sheets witlr- 45,

out the fine perforations becoming choked, the holes are preferablyfilled, before drying, with a salt or the like'of low melting point. The block is then cut into sheets'so that sheets of a thickness of from 0.3 to 3 millimeters, or even of other 60 thicknesses if required, are obtained.

Instead of impressing the ducts by inserting wires of harder metal, they may be produced by moving the metal plates adjacent a profile roll as shown-in Fig. 5. If a profile roll is employed, as

during the pressing which are thus given the same form, as theplates j 5 that have been treated with wires and illustrated in Figures 1 and 2. While only one profile roll is shown in the drawing it will be apparent that grooves may be provided in both faces of a plate bypassing the metal sheet between two such rolls.

In order to obtain a in every respect, it is block which is homogeneous necessary for the materials of the plates and of the wires to be correctly related to one another. For instance if it is de sired to obtain thin sheets of tantalum, difllculties are liable to arise because the metal has a high fusion temperature. By coating the tantalum plates in advance, however, by electrolytic means for example, with a thin layer of nickel of a thickness of 0.00l'of a millimeter, the fusion operation, even at a low temperature, is sufficiently accelerated, so that the inconvenient property of tantalum is thereby obviated. Other metals may also be employed for this purpose, for instance iron or niobium, or in 26 any case a metal that combines easily with tantalum. Obviously the wires inserted must also be of a metal having a high fusion temperature, such as tungsten'ormolybdenum wire for ex-.

ample. Instead of tantalum, niobium may be 80 employed.

85 which may 40 and the like, or by alloys,

Alternatively the method may be modified by using plates of metal that are very stable chemically, such as tantalum, niobium, gold, platinum or the like, and selecting wires of base metal, then be left in between the metal plates during the pressing, and only etched away after the block has been finished.

Tantalum and niobium may alternatively be replaced by cheaper metals, such as nickel, iron such as the steel alloy marketed under the trade mark V2A, vacuum fused alloys, or the like. With these metals, however, the material of the wire'must be very carefully selected, in orderthat when the wire 48 is subsequently being etched away the material I. ployed in spinning nozzles,

block has been produced,

of the plate may not be attacked. For this rea-v son it is preferable to take the wires out before the fusion.

when perforated metal sheets are to be emit is necessary that the sheets should be chemically stable. If a nickel first not chemically stable. They may however be made chemicaly stable by exposing the nickel "sheets to an atmosphere of tantalum, niobium,

, l'a reaction of the chloride 65 this manner there is formed tungsten, or molybdenum chloride, or some other halogenide. Compounds of boron may alternatively be employed instead. Such a chloride at-. .mosphere i's-of such a high temperature that with the nickel or other metals employed occurs, while the metal of the halogenide, the tantalum for example, is deposited upon the nickel, and, in consequence of the high temperature, diffuses into the nickel. In inside the capillaries and around the apertures a uniformly thin and chemically stable coating.

Such coated nozzles also have the advantage that it is possible in a certainsense to harden 70 them without affecting the surface color of the metal. The hardening may be effected in the case of tantalum and niobium coatings, for example, by means of hydrogen, as a result of which a layer of tantalum hydride or a layer of niobium 78 hydride is formed, which is exceedingly hard and the nickel sheets are at metallic layer or with boron or with oxygen. A 5

similarly very hard layer is obtained by coating solid tantalum nozzles with a layer of tungsten.

Although several preferred embodiments of the invention have been described it is apparent that modifications may be made therein by those skilled in the art. Such modifications may be made without departing from the spirit or scope of the invention as set forth in the appended claims.

. What I claim is:

l. A method of producing thin sheets of metal provided with uniform holes of small diameter, which comprises, superposing polished plates of metal with a layer of parallel wires of harder material between each two adjacent plates to form a block, applying pressure to the block until the wires have been forced into the surface of the metal plates and are in contact with the latter throughout their surface, removing some of the wires from each layer, applying pressure and heat to the block and thereby converting it by fusion into a homogeneous body, and cutting the homogeneous body thus formed into thin sheets.

2. A-method of producing thin sheets of metal provided with uniform holes of small diameter which comprises, forming parallel grooves in the faces of polished metal plates, arranging a wire in some of the grooves, superposing the plates to form a block with some of the grooves engaging said wires, applying pressure and heat to the block and thereby converting it by fusion into a posing polished plates of said metal with a layer.

of parallel wires of base metal between each two adjacent plates to form a block, applying pressure and heat to the block and thereby converting it by fusion into a homogeneous body, cutting the homogeneous body thus formed into thin sheets, and removing the wires by etching.

4. A method of producing perforated thin sheets of chemically stable metal such as tantalum, niobium, gold and platinum which comprises, coating polished plates of said metal with a thin layer. of nickel, superposing the nickelcoated plates with a .layer of parallel wires of base metal between each two adjacent plates to form a block, heating the block in a vacuum and applying pressure'to the block thereby converting it by fusion into a homogeneous body, cutting the homogeneous body thus formed into thin sheets, and removing the wires by etching.

5. A method of producing thin sheets of nickel provided with uniform holes of small diameter which comprises, superposing polished plates of nickel with a layer of parallel wires of base metal between each two adjacent plates to form a block, app fi pressure and heat to the block and thereby converting it by fusion into a homogeneous body, cutting the body into thin sheets, removing the wires by etching, and hardening 7 the thin perforated sheets thus produced by exposing them to an atmosphere of metal chlorides.

6. A method of producing thin sheets of tantaluni provided with unifomi holes of small diameter which comprises, superposing polished I plates of tantalum with a layer oi parallel wires' of base metal between each two adjacent plates toform a block, applying pressure and heat to the block and thereby converting it by fusion into a. homogeneous body, removing the wires by etchin cutting the homogeneous body thus formed into thin sheets, and hardening the thin perforated sheets thus produced by coating them with a metallic layer which forms a hard alloy with the tantalum.

'1. A method of pr'oducingthin sheets or tantalum provided with uniform'holes of small diameter which comprises, superposing polished plates of tantalum with a layer of parallel wires etching.

etching, cutting the homogeneous body thus formed into thin sheets, and hardening the thin perforated sheets thus produced by the action of gases which combine chemically with the metal to form a compound which is of greater hardness than the metal.

8. A method of producing thin sheets of metal provided with holes of small diameter which comprises, superposing plates of metal with a layer of wires of harder material between each two adjacent plates to form a block, applying pressure and heat to the block so as to convert the same by fusion into a homogeneous body, cutting the homogeneous body thus formed into relatively thin sheets, and removing the wires by 15 BERNHARD WEMPE.

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