DE1161530B - Process for producing porous wall structures - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school KI .: B21f

German classes: 7d-6

Number: 1161 530

File number: C168861 b / 7 d

Filing date: May 21, 1958

Opened on: January 23, 1964

A known method forming the starting point of the invention in the production of porous wall structures, z. B. bearing, consists in superimposed layers of a by winding on a mandrel prefabricated wire mesh first a preliminary fusion process at the contact points to subjugate. It then becomes the case against wire shifts secured tissue by reducing its thickness and adjusting its interstices or pores and with enlargement of the wire contact surfaces, for example by pressing or rollers, deformed without cutting into bearing bushes, in particular of a self-lubricating type. This is followed by the third process step, in which the wire mesh under final binding of its wires on their now exposed to a new merging process and enlarged, whole contact surface so that the pore condition is fixed. In a similar way, according to an older law, when manufacturing fine-pored Perforated sheets made of fine wire mesh. This procedure can be used to make braided Mats are used where it matters, the size of the passage openings exactly to one set a predetermined value.

It has been observed that the contacting surfaces of the wire mesh are not always flawless weld, because in the first of the above three process steps, in which by the action of heat a fusion and thus a safeguard against displacement of the braid is achieved, the individual wires of the braid lie more or less loosely on top of one another, so that individual crossing points do not or only poorly weld to one another.

In contrast, the object of the invention is to provide a porous wall made of a prefabricated wire mesh to create, the touching surfaces of which are perfectly welded, so that - and it comes to it it here - an emigration during subsequent forming is definitely prevented. The porous Wall can be made in the form of a tube, a cone or a Venturi nozzle or from these starting shapes reshaped or cut into an asymmetrical shape and spread out into an arch. Here it must be possible to change the porosity of the wall exactly to accommodate the different surfaces determine in advance the relative fluid flow present.

In order to solve this problem, the invention makes use of the measures known per se in the production of porous wall structures, according to which these are made by winding underlay a, for example, ab method for producing porous ones
Wall structures

Applicant:

California Institute Research Foundation,

Pasadena, Calif. (V. St. A.)

Representative:

Dr.-Ing. K. Boehmert

and Dipl.-Ing. A. Boehmert, patent attorneys,

Bremen 1, Feldstr. 24

Named as inventor:

Harry Lindsay Wheeler Jr., La Canada, Calif.

(V. St. A.)

flat wire on a mandrel in several intersecting and leaving a gap between them Layers are created as the first step.

The invention consists in the present case that the winding of the strand material on the mandrel here also takes place with strong withdrawal and that the first fusing process on the mandrel, i. H. at under tension takes place wire.

The method according to the invention ensures that all contacting surfaces are weldable instead of lying on top of each other and therefore merge perfectly. An emigration during later reshaping no longer occurs.

The porous wall produced by the method according to the invention is for use as a combustion chamber wall suitable because they serve as a coolant or fuel fluid can be passed through, which forms a protective layer.

The porous wall can also be used to produce a turbine blade, namely an impeller or stator blade, can be used, which is an outward diffusion of coolant or propellant enables. The novel porous wall can be made thin enough and with a large area to to be used as an aerodynamic surface, for example for boundary layer influencing

so sung or distance is used. she can also be designed so that it forms an effective filter.

309 780/49

The invention, the scope of which is defined by the claims, will be described below with reference to the drawing as well as in the context of very detailed explanations to understand the facts described. In the drawing is

F i g. 1 is a very greatly enlarged partial view of a first embodiment of the porous according to the invention Wall,

F i g. 2 is a schematically illustrated section of the wall along line 2-2 of FIG. 1,

Fig. 3 is a similar section along line 3-3 of Fig.l,

4 shows a greatly enlarged partial section of successive ones Wire layers of the porous wall,

Approximately a relatively flat wire advantageous, for. B. a wire, the thickness of the width behaves like 2: 1. To such a flattening of the wire is either before it is wound onto the Mandrel or passed between rollers when winding on the mandrel. The flat profile results in a Maximum area on which the following wire layers rest with pressure, so that in this way appropriate Areas are created that connect when heated ίο.

The wire cross-section or the wire area is determined according to the intended use and the size of the mandrel supporting the wire winding. The bigger the thorn, the stronger

F i g. 5 a partial cross-section along line 5-5 of FIG. 15 can be the wire used. In all cases it can

Fig. 4,

FIG. 6 shows an enlarged partial section similar to FIG. 2 a modified porous wall in which the porosity is between the two wall surfaces changes,

7 shows a schematically illustrated section of two layers of wire lying one on top of the other before heating and merging,

FIG. 8 is a section similar to FIG. 7 wires that fuse when heated,

FIG. 9 shows a partial section similar to FIG. 7 coated or clad wires,

FIG. 10 is a section similar to FIG. 9 in FIG coated wires after their connection, in which

very thin wire can be used. For example, wire with a thickness of 0.05 mm is flattened on 0.025 mm, has been used successfully. There will first be an initial amalgamation between

ao the wires are made by heating the wires wound on the mandrel, then removing the mandrel, then subjected the porous wall formed from the wire to mechanical pressure and then the merger heated up again and completed. The wire can, as shown in Fig. 13, wound in a cylindrical shape, then preliminarily fused, then removed from the mandrel and cut lengthways, then into one

Sheet laid out flat, then fused between rollers behind the coating of adjacent wires, _{carried out 30} and then to consolidate the fused

11 is a partial cross-section showing schematically a tongue to be reheated.

Shows arrangement of pore spaces, which as already mentioned, the wire can be arranged

generate tial flow of the fluid, are wound that many different pore-

Fig. 12 shows a schematically illustrated section of the relationships. Perhaps the simplest form of wall in the flat state, the pore spaces ₃₅ being the wire at a uniform speed.

are inclined relative to the wall surfaces, and FIG. 13 is a perspective view of a one

porous wall having cylinder. To make the porous wall, a thin one is used

on a rotating cylinder in a cross-laying manner. By choosing the rotation speed and the feed, the following wire layers can be superimposed in this way

Wire or fine wire or will be several fine wires that pores arise. The wires can be wound up under tension on a mandrel under tension (Fig. 1, 2 and 3) so that it winds the shape of the finished object or
has a shape from which the finished object is derived

can be provided. In the main there is one

channels or passages 2 are formed which are parallel to each other and parallel to the surfaces of the run this way shaped wall. With the same

Mandrel a body of revolution, e.g. B. a cylinder or a 45-shaped laying delimit the wires openings 3, Cone, or mandrel, has an intricate shape that is perpendicular to the two surfaces of the entz. B. the shape of a Venturi nozzle. By means of a corresponding cylinder or another rotary flange Winding the wire on the mandrel and directed through pers. The porosity is determined by means of the Corresponding choice of cross-section can influence a porous distance with which the wires are attached to the wall whose porosity is uniformly 50 wraps.

or non-uniform or staggered if desired. The wire feed to the rotating mandrel

and is very largely determinable. can also be influenced so that the openings

The wire is wound onto a mandrel, which the following wire layers are not aligned with the openings with the melting temperatures of the wire layers previously laid and the material. The mandrel can for example ₅₅ If the following wire layers, such as F i g. 4 shows whether they are staggered from a ceramic substance or from metal, then the openings are merely made up which are connected to a ceramic substance via the channels 2. As a result, it is drawn or treated in such a way that its several labyrinth passages are formed, which, however, do not connect a surface with the wire. After the uniform distance and the course of which the wire is wound up to produce several can be determined quite well. This type of porous wire layers will be the mandrel with the wall is particularly suitable for pore walls, which as

lent wire subjected to the fusing temperatures, whereby the abutting surfaces of the wire layers are under the action of the tensile stress resulting pressure melt together.

The wire can have a wide variety of cross-sectional profiles and can be round, rectangular or ellipsoidal cross-section, but is experienced

Filters should be used.

It is often desirable that the porosity or permeability of the resulting wire winding structure be maintained changes from one face to the other. This structure can be preserved thereby be that the cross-sectional profile of the wire when winding successive wire layers on the

Thorn is changed. For this purpose, as the wire is wound, a gradual or intermittent one takes place Change the setting of the flattening rollers between which the wire is passed will. The first wire layers 4 (Fig. 6) can be flat, while the following wire layers are less flattened until the end positions 5 (Fig. 6) are kept square or round.

It is of course not necessary for rectilinear pore spaces that these pore spaces are perpendicular to the Finished wall surfaces run. By selecting the feed speed accordingly, you can the subsequent wire layers are slightly offset or displaced so that the pore space 6 (Fig. 11 and 12) is directed essentially tangentially. When making a cylinder you can the axes of the pore spaces both tangential and oblique to one end or to the other Run to the end of the cylinder.

As mentioned, the mandrel used to form the porous wall can be in the form of a finished article have provided that this object is a solid of revolution or an approximation of such a body of revolution, e.g. B. is an ellipse or a polygon. So shows z. B. Fig. 13 a cylinder shape ?. By changing the feed speed of the wire when it is wound, the obtained porosity can be changed so that, for example, in an internal combustion engine, the greater porosity is present at the zones where a major fluid delivery is to be made.

As a result of the preliminary fusion established between the wires, it is possible to create a one Cut open the cylinder having porous wall after binding and then close a flat curve form. Such an arch can be further deformed. The cylinder 7 can, for example, on the Line 11 (Fig. 13) can be cut or separated to form a flat surface. However, it is not necessary to cut the cylinder or other manufactured shapes; such a body can can also be pressed to the desired final shape.

The metal used to manufacture the wire is porous according to the intended use Wall chosen. Steel, copper, titanium and molybdenum wires can be used, but also wires made from alloys be used. The types of wire mentioned are just a few of the many types of wire that are used for production can be used. The wire can also have a cladding 16 (Figs. 9 and 10) or a have another coating. In this case the fusion temperature need only be so high that that the coating material melts. A steel wire clad with copper can therefore with a lower Temperature connected or fused as a non-clad steel wire.

It is always important that the wire is wound up under such strong tension that a high one Radial pressure between successive wire layers at the crossing point of the wires is. The tensile stress acts in the entire winding body; but only as long as this winding body is on the mandrel. The preliminary or initial fusion takes place by heating the wire wound on the mandrel, whereby the tension exerted by the wire tension generates the pressure necessary to achieve a safe Fusion is required at the temperatures used. After the winding body has been removed from the mandrel and when it is pressed together on a smaller dimension are the wire sections, which are close to the preliminary fusion are deformed, and the contact surfaces between the wires are expanded or enlarged. Since the wire is still tightly wound when it is deformed, between the wire surfaces at the extensive contact points a pressure, so that the final heating due to the heat and the existing pressure, the necessary fusion between making the wires. When the dome is pressed together after the dome has been removed porous wall, the wires of the wire layers are pressed closer together, so that in this way Passages of smaller dimensions are created than present at the beginning of the compression process was. It is so the production of porous walls with very fine wall passages and moreover the precise manufacture of the uniformity and porosity of the product is possible. The porosity is known not only by the initial distance and the dimensions of the wound wires, but also determined by the size of the compression pressure. Gets a proportionate from the reels slight rolling pressure is exerted, then for a certain initial distance of the wires a highest permeability or porosity obtained, while under the action of strong rolling pressure the Porosity is reduced accordingly.

Although the greatest rolling pressure is forcibly applied after the mandrel has been removed, a preliminary rolling operation can also be carried out after the porous wall has been bonded if the porous wall is still on the mandrel. This machining process loosens the structure of the porous wall. If a thin ceramic spread has been used on the mandrel as a separating material, the spread will be broken in such a first rolling process and, as a result, the removal of the porous wall will be facilitated.
The distance between the individual wire windings and the relative position of the wires present in successive windings enables the production of a porous wall which has precisely the desired permeability and the desired flow resistance. For a given porosity or permeability, the flow resistance can be increased or decreased depending on the position between successive wire layers.

When using a single wire or when using multiple wires, the winding pitch becomes always chosen so that the wires of successive wire layers are in a known manner cross at a substantial angle so that the resulting wall structure such as that shown in FIG Cylinder 7, has a favorable longitudinal and circumferential strength.

When using a single wire, many wire strokes of the wire are required before the between The gaps between the initial windings of the wire are filled. As a result, take place the intersections of the wires at periodic points along the wire winding body. Any increase in thickness at these points after the first heating and fusing of the wires

see the flattening rollers passing through the porous wall prevented.

When the wire is filled or finished by repeatedly moving the wire back and forth first wire layer, a second wire layer is also completed, due to the fact that there is also a return stroke with each forward stroke. Each layer of wire corresponds to a number of Wires shown in Figs. 2, 3, 5 and 6 to 7, i.e. the first wire layer corresponds to that in The lower row in these figures and the second wire layer corresponds to that in these figures second row etc.

The coiled wire groups of the same size resulting from the total number of forward strokes or return strokes exist are not identical to the first wire layer and the second wire layer, especially after the compression of the wall structure produced in this way, from the following Reasons. The wire sections of the wire layer wound on the forward stroke lie above the wire sections of the wire layer wound on the return stroke and are consequently pressed into the second wire layer. Similarly, sections of the beim Return stroke wound wire layer is pressed into the first wire layer. This press-fit deforms each wire and shifts it from one wire layer to the other wire layer, so that a reinforced connection or Fusion at these spaced-apart locations after the first heating and fusion he follows. As the wire continues to be wound, additional pairs of wire layers are formed.

When winding the wire onto the mandrel by cross-laying, the slope must be at each end Zero and then reversed again, so that a wire pile at each end of the wire winding body arises. If the resulting reduction in permeability in these end zones in the end product is disadvantageous, these end zones must be separated after binding. In many cases it will be however, these end zones are welded or otherwise attached to other parts. In other Cases is the reduction in permeability and the corresponding increased density and strength of Advantage.

It is of course necessary that the ends of the porous bobbin wound on the mandrel are attached stay in place and do not move in the axial direction. Is the pitch angle of the winding less than 20 degrees, then the frictional contact between the wire and the mandrel is like this large that there is no axial displacement of the wire.

However, if the wire is wound at angles of inclination which are greater than 20 degrees, then the wire must be laid in a tendon over the end of the mandrel. The position of the tendon will be like this chosen that the angle formed by the arched under a size of about twice of the pitch angle. Becomes the front ends of the wire winding body forming the porous wall Wrapped in this way, then the pitch angle can have a size of 60 degrees or can be even larger if desired. A slope angle of 45 degrees gives the manufactured porous body have the same strength in the longitudinal direction and circumferential direction. At an angle of incline, which is greater than 45 degrees, the strength in the longitudinal direction is greater than in the circumferential direction. The strength properties of the porous wall can therefore meet the respective requirements be adjusted. A turbine blade, for example, must have greater longitudinal strength while a high-pressure filter must have a greater circumferential strength.

Although it is not necessary to use the front end of the mandrel or one located on the mandrel Wrap shoulder when the angle of incline is less than 20 degrees. However, experience has shown that This ensures uniformity, especially when winding large-diameter wire winding bodies improved.

Claims (5)

Patent claims: 1. A method for producing porous wall structures in which layers are laid one on top of the other one prefabricated by cross-winding wire-shaped ropes onto a mandrel The fabric is first subjected to a first fusing process, then this against wire shifts secured tissue after removal from the mandrel with reduction of its thickness and its interstices as well as with enlargement the wire contact surfaces, for example by rolling, deformed without cutting and then for binding of the wires exposed to a new fusion process on their entire contact surface is, characterized in that the winding of the strand material on the mandrel in a known manner with strong retraction takes place and that the first fusing process with the wire under tension on the Dorn is carried out. 2. The method according to claim 1, characterized in that the further steps, that is reshaping and remelting in the usual way after removal of the workpiece be carried out by the mandrel. 3. The method of claim 1, wherein the tubular workpiece after stripping from The mandrel is slit lengthwise and spread out to form a flat plate, characterized in that that the plate is rolled out. 4. The method according to claim 1, characterized in that the forming in on the Workpiece located in the mandrel takes place. 5. The method of claim 1, wherein the tubular workpiece after the first fusing process is reshaped, characterized by its reshaping into an asymmetrical body. Considered publications:
German Patent No. 750 144;
Swiss Patent No. 107 672;
U.S. Patent Nos. 2,100,159,1198,349. Legacy Patents Considered:
German Patent No. 1115 699. 1 sheet of drawings 309 780/49 1.64 @ Bundesdruckerei Berlin