US2882554A

US2882554A - Production of strips or bands from metal powder

Info

Publication number: US2882554A
Application number: US532320A
Authority: US
Inventors: Heck Friedrich
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-09-02
Filing date: 1955-09-02
Publication date: 1959-04-21
Anticipated expiration: 1976-04-21

Description

F. HECK April 21,-1959 PRODUCTION OF-ISTRIPS 0 BANDS FROM METAL POWDER 2 Sheets-Sheet 1 Filed Sept. 2, 1955 F. HECK April 21, 1959 PRODUCTION OF STRIPS 0R BANDS' FROMME'IAL POWDER Filed Sept. 2, 1955 2 Sheets-Sheet 2 I ////l fill/Ill)! Unite PRODUCTION OF STRIPS OR BANDS FROM METAL POWDER In the known processes the production of strips and sheets from metal powder, more particularly copper powder, is effected by first of all consolidating a layer of powder by means of rolls, so that a self-supporting bandshaped body results. Thereupon, sintering and reconsolidating follows alternately in separate operations by means of rolls. After finish rolling, an annealing process is applied, if necessary.

The finishing of strips presents special difficulties during reconsolidation by means of rolls. These difliculties are due to thecircumstance, that the strip after the first operation permits of only very slight rolling down. During reconsolidation the strips have to run through the rolls without guiding means, as any contact with a guiding element will tend to fold over the edge of the strip and may cause a fracture of the strip. Furthermore it is only possible to operate with a very slight braking and reeling tension. Any racing of the reeling up appliance during winding up may, in the case of heavy rings, result in a destruction of the strip which after the first operation is still very brittle. Owing to the great sensitiveness of the copper strip, when first formed, and the lack of lateral roll table guides, referred to above, only low rolling speeds can be employed. The known methods are thus not very efficient, more particularly, as only costly electrolytic copper powder can be used in the process.

The above described disadvantages have led to the consideration, as to whether it might not be possible to make use of cheap copper powder obtained by a wet chemical process. A processing of the copper powder produced in this way is, however, not readily possible, as the form of this powder is globular, whilst the hitherto used electrolytic copper powder is finely divided. When using a finely divided powder a good mechanical interlocking of the powder particles is brought about, which presents certain difiiculties in the case of a powder of globular formation; for preconsolidated strips formed of globular copper powder have very slight inherent strength, so that such strips may very easily fracture. The invention sets out to solve the problem to develop a process and an arrangement for enabling copper powder of globular formation, which has been produced by wet chemical means, to be worked up.

According to the invention the metal powder, more particularly copper powder composed of powder particles of globular formation, is heated to about red heat and is in this state fed to the roll gap. The consolidation and sintering of the powder takes place simultaneously through roll pressure and under the action of heat, the rolls being heated and giving off their heat to the metal powder which is kept under the action of a protective gas, for instance H In this arrangement the rolls are heated up preferably to a temperature of about 600 C. In certain circumstances, it is however, possible to heat up the metal powder only, which during the rolling process continuously gives oif heat to the rolls which by means of their consid- States Patent ICC erable mass store up the heat imparted to them. But these two processes may also be combined in such a manner that there will be both a direct heating up of the rolls and a heating of the metal powder.

An essential feature is thus, that for the sintering process sufiicient heat should be available.

For carrying out this process a particularly suitable rolling mill is one which is provided with obliquely superposed rolls and in which the plane containing the axes of the upper and lower rolls is at an angle to the vertical of about 25. In such a rolling mill the rolls may be directly heated. According to the invention it is therefore proposed to support and drive both operative rolls by a number of small rollers which are in engagement with the upper and lower convex surfaces respectively of the operative rolls. Such an arrangement provides the possibility of strewing on the metal powder laterally from the crown of the lower roll, which conveys the powder in a uniform layer to the gap between the rolls. In accordance therewith there is provided on the opposite side a delivery duct provided with stripping members extending into the roll gap. According to the invention provision must be made for protecting the metal powder from oxidation. With this object in view, according to the invention the space, through which the said metal powder runs, is closed to the outside and filled with protective gas.

For the rolls themselves a heat-resisting and non-scaling material must be employed. The heating up of the operative rolls may be effected both with gas burners and in accordance with the electric resistance welding principle. It is also possible to arrange the two operative rolls as electrodes.

For the rapid cooling of the rolled strip a cooling space may be provided on the delivery side.

A rolling mill according to the invention is diagrammatically illustrated in the accompanying drawings, in which:

Figure 1 shows the mill as a whole in side elevation;

Figure 2 shows the receiving duct and associated details in sectional elevation;

Figure 3 is a perspective view of the receiving duct;

Figure 4 shows the feeding duct and cover in sectional elevation; and

Figure 5 is a perspective view of the cover alone.

This rolling mill has two operative rolls 1 and 2, which are supported and driven by supporting rollers 3. These supporting rollers may have to be cooled. The two operative rolls are arranged obliquely one above the other. The heating of the operative rolls 1 and 2 is effected by means of burners 4. Laterally of the crown of the lower roll 2 is the feed inlet or feeding duct 10 for the powder, from which the powder passes on to the convex surface of the operative roll 2 which conveys the uniformly deposited powder in the form of a strip or band to the roll gap. At the end of the powder feed inlet 10 is a covering device 6, including lateral walls 13 shown in Figure 5 the purpose of which is to form a closed space which is filled with protective gas H admitted to this space, and also to the feeding duct 10, through inlets 14 as indicated, whilst on the under side the metal powder itself acts as a seal. From the orifice of the duct 10 to the roll gap 7 the requisite heating of the metal powder takes place, which is then consolidated in the roll gap 7. After leaving the roll gap 7 the consolidated strip or band 12 passes into a channel-shaped cooling space or receiving duct 8 which is provided with strippers 9 extending into the roll gap. The interior of the cooling space 8 which is in open communication with the space closed by the cover 6, is also filled with protective gas, admitted through an inlet 15. Provision is also made for a cooling jacket 16 which is swept through, for instance, by cooling water,

3 admitted through an inlet 17 and discharged through an outlet- 18. The receiving duct is provided with taperinglateral extensions 19 extending rearwards past the strippers 9 so as to close the roll gap at the sides.

As already stated; the operative rolls l an'd 2 are in theconstructional example illustrated, guided and driven only by rollers 3. This-signifies, that thethick ness' of the roll gap 7 is filled by the amount ofmetal' powder fed'in; the thickness of the roll gap being determined by the position of the guide rollers 3;

For reducing the loss of heat, the operative rolls 1, 2 may be provided with a housing 11.

I- claim:

1. A rolling millv for producing strips ofmetal from metal powder, particularly copper powder, comprising: two operative rolls arranged obliquely one above the other, a duct for feeding metal powder to the upper surface ofthe lower roll at a position preceding its highest part, means for heating the rolls to a temperature high enough to sinter the metal powder, a plurality of rollers, of a diameter smaller than that of the operativerolls, bearing against the peripheries of the operative rolls so as to support them and urge them towards one another, a duct on the opposite side of the operative rolls from the feeding duct, adapted to receive the metal strip formed, and strippers in the receiving duct, bearing against the peripheries of the operative rolls.

2. A rolling mill as claimedv in claim 1, further comprising a cover, enclosing, in conjunction with the feeding duct and the peripheries of the operative rolls, a space within which the metal powder travels on the surface of the lower roll from the feeding duct to the gap between the operative rolls, this space being in communication with the receiving duct, and the mill further comprising means for supplying a protective gas to the receiving duct and the space enclosed by the cover and the feeding duct.

3. A rolling mill as claimed in claim 1, further comprising jackets enclosing the operative rolls, but not enclosing the rollers that bear against the peripheries of the operative rolls, and burners for heating the rolls, located between the roll peripheries and the jackets.

References. Cited in the file of this patent UNITED STATES PATENTS 1,380,632 Bowden June 7, 1921 1,556,658 Williams Oct. 13, 1925 1,667,884 Cremer May 1, 1928 1,792,999 Messner Feb. 17, 1931 2,134,366 Hardy Oct. 25, 1938 2,170,732 Sendzimir Aug. 22, 1939' 2,197,022 Petterson Apr. 16, 1940 2,271,459 McConnell Jan. 27, 1942 2,287,663 Brassert June 23, 1942 2,341,732 Marvin Feb. 15, 1944 2,693,012 Harris et a1. Nov. 2, 1954 2,717,419 Dickey Sept. 13, 1955 2,771,637 Silvasy etal. Nov. 27, 1956