US3017665A

US3017665A - Rolling mill

Info

Publication number: US3017665A
Application number: US708530A
Authority: US
Inventors: Dasher John; Melvin C Chang
Original assignee: Crucible Steel Company of America
Current assignee: Crucible Steel Company of America
Priority date: 1958-01-13
Filing date: 1958-01-13
Publication date: 1962-01-23
Anticipated expiration: 1979-01-23

Description

J. DASHER ETAL 3,017,665

ROLLING MILL 2 Sheets$heet l ATTORNEY I INVENTORS John Dosher 8 Melvin Chen-Siong Chung. BY -M7 Jan. 23, 1962 Filed Jan. 15, 1958 Jan. 23, 1962 J. DASHER ET AL 3,017,665

ROLLING MILL Filed Jan. 13, 1958 2 sheets sheet 2 Fig.4

L f 1 l I t l Fig.6

Fig.5

United States This invention relates to apparatus for compacting metal powders into wrought metal sheets and more particularly to apparatus for rolling metal powders into metal sheet having a uniform density and compactness across the entirety of its width.

In rolling metal powder into wrought shapes, fine dustlike particles are introduced into a roll gap formed be tween horizontally spaced rolls. As the metal powder passes through the gap, it is subjected to a rolling pressure sufficient to cause the metal powder particles to cohere. Thereafter, the resulting wrought metal article is subjected to a sintering treatment in order to increase the strength and ductility of the compacted article; and, finally, the wrought metal article is further rolled, either hot or cold, to elfect a further compacting thereof.

The edges of a sheet produced in a conventional powder rolling process of the type described above are generally jagged and rough. When the metal powder is compressed between the rolls, a green or unsintered sheet is obtained which has a uniform density across the center area, but a lower density at the edges where the powder is free to be pressed sideways and even to fall through the rolls uncompressed. When such a sheet is sintered and re-rolled, the dense center elongates while the porous edges compact but do not elongate, thereby resulting in a cracked edge.

It is an object of this invention to provide a novel metal powder rolling mill which will produce green sheet or strip having a uniform density across its width, thereby resulting in a finished product having dense edges free from cracks. As will become apparent from the following description, the foregoing object is achieved by providing flanged portions on one end of each of the rolls, or on opposite ends of one of the rolls, which extend over the ends of the roll gap to provide a positive stop against which the metal powder may be pressed during a rolling operation. In this manner, sideways movement of the metal powder is limited at the edges of the rolls so that the densityof the article .is the same across'its entire width. I

Another object of the invention is to provide a rolling mill arrangement of the type described above in which friction and wear between the aforesaid flanges and their cooperating rolls are minimized.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification and in which:

FIGURE 1 is a side view of one embodiment of the invention;

FIG. 2 is a top view of the embodiment of the invention shown in FIG. 1;

FIG. 3 is a detailed view of the antifriction hearing atrangement interposed between a flange on the roll shown in FIG. 2 and the body of its cooperating roll;

FIG. 4 is a top view of another embodiment of the invention;

FIG. 5 is a detailed view of a roll flange arrangement which may be used in either of the embodiments of FIG. 1 or FIG. 4; and,

FIG. 6 illustrates still another roll flange arrangement which may be used in either of the aforesaid embodiments.

Referring to FIGS. 1 and 2, the embodiment of the invention shown includes a pair of

roll housings

10 and 12 ice which carry two horizontally spaced rolls 14 and 16. Roll 14 has two

neck portions

18 and 20 at its opposite ends which extend into

tapered journal bearings

22 and 24 carried in

housings

10 and 12. In a similar manner, roll 16 has two

neck portions

28 and 30 at its opposite ends which extend into

journal bearings

32 and 34 which are carried on two bearing chocks 36 and 38. The chocks, in turn, may be adjustably positioned on

guideways

40 and 42 formed in

housings

10 and 12. As will be understood, the roll gap 44 between rolls 14 and 16 may be varied in width by adjusting two screw-

downs

46 and 48 which force chocks 36 and 38 to move along

guideways

46 and 42. Means, not shown, are connected through universal couplings to the right and left ends of portions Zll and 28, respectively, for rotating the rolls in opposite directions, but at the same speed.

The left and right ends, respectively, of rolls 14 and 16 are provided with

flanged portions

50 and 52 which overlap the left and right edges, respectively, of rolls 16 and 14-. The arrangement is such that flange 50 on roll 14 will be forced into sliding engagement with shoulder 54 of roll 16. Similarly, flange 5?. on roll 16 will be forced into sliding engagement with shoulder 56 on roll 14. The amount of pressure existing between the flanges 5t) and 52 and their cooperating shoulders may be adjusted by turning the two screw-downs 58 and 60 which engage the ends of the left and right neck portions, respectively, of rolls 14 and 16. In the particular embodiment of the invention shown in FIGS. 1 and 2, annular roller bearings 62 and 64 are carried by

shoulders

56 and 54, respectively, and engage the flanges 52 and 55) to reduce sliding friction between the two members. In FIG. 3, the details of the annular roller hearing are shown and comprise an inner race 66 which is fitted within annular channel 68 and an outer race 70 which abuts the shoulder of the opposing roll. Rollers 72 are interposed between the inner and outer races whereby substantially unimpeded movement between the races may be achieved. As will be understood, a certain amount of sliding friction will exist even with thepresence of the bearings, but the average velocity between the sliding parts is materially reduced.

Mounted on the

housings

10 and 12, as shown in FIG. 1, is a hopper 74 having an intermediate portion 76 of somewhat cylindrical cross section and in which is mounted a dispensing device 78 having a plurality of radially extending vanes 80 aflixed thereto. The dispensing device 78 is keyed to a shaft 82 which is journaled in the side walls of the intermediateportion 76, and this shaft is drivingly connected to a motor device, not shown. During operation of the mill, the dispensing device is rotated in timed relationship with rolls 14 and 16 so as to discharge measured quantities of metal powder to the roll gap 44 at a rate proportional to the speed of operation of the rolls. The hopper 74 has a downwardly extending tapered discharge spout 84 which is adapted to direct the material discharged from the hopper into the roll pass 44.

In operation, rolls 14 and 16 will rotate in the direction shown by the arrows in FIG. 1. At the same time, dispensing device 78 will forward measured quantities of metal powder from hopper 74 to the roll pass 44. In the rolling operation, metal powder will tend to move sideways toward the edges of the rolls. If positive stops such as

shoulders

50 and 52 are not provided to limit this sideways movement, metal powder will be elfectively squeezed out of the ends of the roll pass 44; and, consequently, the density of the green sheet at its edges will be less than in the center. However, by providing the

shoulders

50 and 52, such sideways movement is limited or stopped whereby the metal powder must pass through the roll pass 44 at its edges rather than being spread out over the edges of the rolls.

As shown in FIG. 1, the resulting green or unsintered sheet passes from the rolls to a sintering furnace 86 where the continuous sheet is heated under a controiled atmosphere to prevent oxidation of the same. Thereafter, the sintered sheet from furnace 86 is again rolled by rolls 88 and 90 to further densify the wrought metal article.

In FIG. 4, the embodiment of the invention is similar to that shown in FIGS. l3, except for the configuration of the rolls. Since many of the elements of FIG. 4 are similar or identical to elements of FIGS. l3, they are identified by corresponding identification numerals and are not described hereafter. As shown in FIG. 4, two

rolls

100 and 102 are provided in an arrangement similar to that of FIG. 2, but in this case both ends of the one roll 102 are provided with

flanged portions

104 and 106, whereas neither end of the other roll 100 is flanged. The working

faces

105 and 107 of

portions

104 and 106 are beveled or rounded so that a close fit is obtained only at the points of contact 108 and 110. In this arrangement, as was the case in FIG. 2, the ends of the roll pass 44 are effectively closed off whereby sideways movement of the powder within the roll pass is limited or entirely stopped so that a product is obtained having a uniform density across its entire width. It will be noted that in this embodiment of the invention both rolls may be driven from the same side of the mill through necked-down

portions

18 and 28.

FIGS. and 6 illustrate further modifications of the roll flange configuration which may be used in place of those shown in FIGS. 2 and 4, depending upon requirements. In FIG. 5, the end of the one roll 110 is beveled inwardly and away from the working face 112 on the flange 114 of the other roll 116. The end of roll 110 must be beveled to an extent suflicient to prevent particles of the powdered metal from being smeared across the working face 112; however, the bevel should not be sharp enough to allow any appreciable deflection of the work roll face. In FIG. 6, one roll 118 has its end beveled inwardly while the working face 120 on the flange 122 of the other roll 124 is beveled outwardly. This arrangement will obviously further insure against smearing of metal powder between the end of one roll and the working face on the flange of the other roll.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

We claim as our invention:

1. Apparatus for compacting metal powder into a wrought metal sheet comprising, in combination, first and second axially aligned and horizontally spaced apart compacting rolls defining a roll gap therebetween, said roll gap being adaptable for forming sheet from powdered metal, the first of said rolls having annular flanged portions at its opposite ends which extend over the opposite ends of said roll gap to form positive abutments at the ends of the roll gap, and beveled surfaces on said flanged portions line-contacting end edges of said second roll to seal the ends of said gap and extending curvilinearly outwardly from the opposite ends of said second roll to prevent particles of metal powder from being smeared across the ends of said second roll and said beveled urfaces on the flanged portions.

'2. In combination with a pair of horizontally disposed and spaced apart forming rolls for compacting metal powder into a wrought metal sheet, an integral annular flanged portion on an end of one of said rolls which extends across to the other of said rolls and is so constructed and arranged as to make a substantially frictionless line-contact seal with an opposing face of said other of said rolls and to provide a positive stop at the end of the roll gap formed between said rolls, said roll gap being adaptable for forming sheet from powdered metal, and

a beveled surface on said flanged portion which faces said end of the other roll, said beveled surface abutting said end of the other roll at the radially innermost portion of said flange and gradually curving outwardly as its distance from the axis of said one roll increases.

3. In combination with a pair of horizontally disposed and spaced apart forming rolls for compacting metal powder into a wrought metal sheet, an annular flanged portion on an end of one of said rolls which extends across to the other of said rolls and is so constructed and arranged as to make a substantially frictionless linecontact seal with an opposing face of said other of said rolls and to provide a positive stop for metal powder fed into a gap formed between said rolls, a beveled surface on said flanged portion which extends curvilinearly outwardly from said end of the other of said rolls, and a cup-shaped surface on said end of the other of said rolls, wherein any escaping metal powder may pass and be removed by gravity, said cup-shaped surface being disposed curvilinearly inwardly and away from said beveled surface whereby particles of metal powder are prevented from being smeared across said end of the other of said rolls and said beveled surface.

4. In combination with a pair of horizontally disposed and spaced apart forming rolls for compacting metal powder into wrought metal sheet, an annular flanged portion on an end of one of said rolls which extends across to another of said rolls and is so constructed and arranged as to make a substantially frictionless line-contact seal with an opposing face of said other of said rolls and to provide a positive stop for metal powder fed into the gap formed between said rolls, and a cup-shaped surface on said end of the other of said rolls, wherein any escaping metal powder may pass and be removed by gravity, said surface extending curvilinearly inwardly from said end of the other of said rolls whereby particles of metal powder are prevented from being smeared across said end of the other of said rolls and said flanged portion.

5. A powder rolling mill comprising, in combination, a pair of roll stands, first and second pairs of tapered thrust bearings carried by said roll stands, a first compacting roll having necked-down portions at its opposite ends which extend into said first pair of thrust bearings, a second compacting roll having necked-down portions at its opposite ends extending to said second pair of thrust bearings, said first and second rolls being axially aligned with the axes of the rolls being horizontally spaced apart to form a roll gap between the rolls, an integral flanged portion at one end of said first roll, said flanged portion having a radially extending shoulder surface which covers one end of said roll gap and is so constructed and arranged as to make a sliding line-contact seal with an opposing face of said second roll at one end, and an integral flanged portion at the other end of said second roll which is opposite the flanged portion on said first roll, the flanged portion of said second roll also having a radially extending shoulder surface which covers the other end of said roll gap and makes a sliding line-contact seal with an opposing face of said first roll at the other end, whereby the shoulder surfaces form positive abutments at opposite ends of said roll gap to limit sideways movement of metal powder fed into the gap, each of said flanged portions beyond their respective sliding line-contact seals extending curvilinearly outwardly from said roll ends whereby metal powder escaping through said sliding line-contact seals is immediately removed by gravity thereby preventing smearing of said powder between said flanged portions and said roll ends.

6. Means for compacting metal powder and forming the same into sheet comprising a pair of compacting and forming rolls spaced apart to form a gap therebetween for reception, compaction and forming of said powder into sheet and means to obtain uniform edge compaction and forming of said sheet without increasing abrasive, and

frictional wear and binding between said rolls, said means comprising flanges on opposite extremities of one of said, rolls, said flanges being provided with surfaces inwardly of said rolls, said surfaces having first portions thereof extending across the width of said gap and substantially normal to the longitudinal axes of said rolls and constituting abutments for the uniform compaction and forming of the edges of said sheet, said surfaces having second portions thereof extending beyond said gap and extending curvilinearly outwardly of said rolls to define a pocket between said second portions and corresponding end surfaces of the other of said rolls, said other roll being horizontally disposed with respect to said one roll in a manner such that end edges of said other roll form a line contact seal with said flanges at the juncture between said first and second portions thereby to seal the edges of said gap, whereby metal powder escaping from said seal passes into said pocket and is removed therefrom by gravity, thereby substantially avoiding undue binding and abrasive and frictional Wear between said rolls.

7. Means for the uniform compaction and forming of metal powder into sheet comprising a pair of rolls, the extremities of one of said rolls being provided with flanges having inner surfaces inclined curvilinear-1y outwardly of said sheet, the extremities of the other of said rolls being provided with concavities which, at a position adjacent the sheet, define powder-receiving pockets with said inner surfaces, said inner surfaces defining sealing edges with the peripheral edges of the extremities of said other of said rolls, said rolls being horizontally disposed with respect to one another and spaced apart to define a gap therebetween, the spacing of said rolls being such that said flanges extend across the gap to form abutments for the compaction and forming thereagainst of edge portions of said sheet and such that the sealing edges of the other of said rolls substantially line contact said flanges to seal the ends of the gap against escape of excessive amounts of said metal powder whereby powder escaping from said gap passes into said pockets from which it is immediately removed by gravity.

8. Means for continuously compacting and forming metal powder into sheet having edge portions of uniform density comprising: a pair of rolls spaced apart to define a roll gap therebetween, an integral flanged portion on an end of one of said rolls and extending therefrom across said roll gap to provide a powder-retaining abutment at an extremity of said roll gap, said flanged portion being so constructed and arranged as to form a substantially frictionless line-contact seal with an opposing face of the other roll.

References (Iited in the file of this patent UNITED STATES PATENTS 611,603 Bradley Oct. 4, 1898 2,158,461 Koehring et al. May 16, 1939 2,341,732 Marvin Feb. 15, 1944 2,397,608 Johnson Apr. 2, 1946 2,548,009 Fether Apr. 10, 1951 FOREIGN PATENTS 1,092,161 France Nov. 3, 1954 24,021 Great Britain Nov. 26, 1901