US2075394A

US2075394A - Method of surfacing metallic rolls for rolling metals and apparatus therefor

Info

Publication number: US2075394A
Application number: US758542A
Authority: US
Inventors: Clarence W Hazelett
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-12-21
Filing date: 1934-12-21
Publication date: 1937-03-30
Anticipated expiration: 1954-03-30

Description

March 30, 1937.

C. W. HAZELETT METHOD OF SURFACING METALLIC ROLLS FOR ROLLING METALS AND APPARATUS THEREFOR Filed Dec. 21, 1934 '2 Shets-Sheet 1 INVENTOR.

CLARENCE l4- HHZELETZ' ATTORNEY.

March 30, 1937. c. w. HAZELETT 2,075,394

METHOD OF SURFACING METALLIC ROLLS FOR ROLLING METALS AND APPARATUS THEREFOR Filed Dec. 21, 1934 2 Sheets-Sheet 2 4 I INVENTOR. I/C'LHREIVCE HOV/725A 5T7;

ATTORNEY.

Patented Mar. 30, 1937 (UNITED STATES PATENT OFFICE METHOD OF SURFACING METALLIC ROLLS FOR ROLLING METALS AND APPARATUS THEREFOR Clarence W. 'Hazelett, Greenwich, Conn.

- Application December 21, 1934, Serial No. 758,542

17 Claims. (01. 22-2001) The present invention relates to a new method of surfacing metallic rolls for rolling metals, and more particularly to the surfacing of rolls used in the production of metallic sheets directly from the liquid state and apparatus therefor.

Heretofore, it has been known that metallic rolls used for rolling metals, either hot or cold, were subjected to rapid deterioration of the rolling surfaces thereof. Thus, after a set of rolls had been in service a variable length of time, the

passes become worn unevenly and the surfaces of the rolls became rough, pitted, grooved, etc. Furthermore, fire cracks were caused by the rolls becoming overheated and cracking on the surface. The aforementioned surface defects of the rolls formed more readily the higher the temperature at which the rolling was carried out, and became very prominent when the temperature approached or exceeded the melting point of the metal being rolled and the rolls came in contact with molten metal, as in the process of forming metallic strips directly from molten metal. The imperfections on the surface of the rolls, such as pit-marks, rough or flat spots, fire cracks, scratches, grooves, etc., caused a similar pattern to be reproduced on the surface of the material being rolled by being periodically impressed thereon with each revolution of the roll. Since the roll marks appearing at regular intervals on the rolled materials were sufficient in most instances to condemn the material, it was necessary to maintain at all times a careful inspection of the rolls and of the material undergoing rolling. When the roll marks on the rolled material were such as to cause rejection of the material, it was customary to remove the rolls from the stand and to grind and dress them to remove the surface imperfections thereof. For instance, in certain rolling mills the rolls were changed every week and dressed in a special roll shop. About was taken out from the surface of the rolls every time they were dressed. It was necessary to keep on hand four sets of rolls and each set was used once in four weeks. It is known that the operation of roll dressing was a highly specialized art which required a high degree of care and skill and entailed a great deal of time and expense. Thus, it was necessary to match accurately a set of two rolls. In order to secure the proper surface finish, it was essential to maintain certain special conditions, carefully determined for every type of material, dur-- ing all stages of the dressing operation. Thus, for instance, it was necessary to determine accurately the turning speed of the rolls undergoing grinding or cutting, the transverse speed of the tools or grinding wheels, the depth of the various cuts, etc., in order to avoid flats, traverse marks, fish tails, orange peel, and other marks. It was of extreme importance to carefully select the most suitable type of tools and abrasives and to have the operation controlled by a sldllful operator. In order to avoid chatter marks, rigid non-vibrating machines were required, special spindles and methods of roll mountings were devised, and the rolls had to be balanced carefully and accurately. Other factors to be observed were the influence of the work temperature to avoid unequal expansion resulting in errors in dimensions, the proper filtering of the coolant to avoid scratching caused by the dirt carried to the roll by the coolant, the type of lubricants for the various parts of the machine, the grinding wheel approach, the pressure of the tools or grinding wheels, and similar conditions. In the prior art, the surface imperfections which were formed on the surface of the rolls during the rolling operations, could be removed only by methods which were expensive and required skillfully handled expensive and. lengthy operations. Furthermore, the rapid formation of fire cracks, pits, scratches, etc. especially when rolling at high temperatures, required'frequent grinding operations which gradually reduced the diameter of the rolls. Under these circumstances the life of the rolls was relatively short, particularly in the case of chilled or other surface hardened rolls in which the hard surface was removed after a few grindings. Although many attempts were made to overcome the disadvantages noted hereinabove, none, as far as I know, was entirely successful and was capable of solving the problem economically and satisfactorily.

It is an object of the present invention to overcome the aforementioned shortcomings and to provide a method of surfacing rolls which is simple, practical, economical and which can be carried into practice successfully.

It is another object of the present invention to provide a method of surfacing rolls which can be readily and successfully applied to existing apparatus, especially mills rolling or forming sheet, strip or the like directly from molten metal.

It is a further object of the present invention condition during the rolling operation.

The invention further contemplates the continuous smoothing out and removal of defects formed on the surface of the rolls during the rolling operation without stopping the operation.

It is still another object of the present invention to provide a roll surfacingdevice by which the present invention can be carried into practice.

Other objects will become apparent from the following description taken in conjunction with the following figures, in which:-

Flg. 1 shows a side elevational view, partly in section, of a preferred embodiment of the present invention mounted in a mill for producing metallic strips directly from molten metal.

Fig. 2 illustrates an enlarged front view of a portion of Fig. 1;

Fig. 3 shows on a larger scale and partly in section a portion of the surfacing device of Fig. 1; and

Fig. 4 depicts on a larger scale a fragmentary view of a portion of ,Fig. 2.

I have found that by subjecting the rolling surface of rotating rolls, for instance, to the action of a hardened flexible rod pressing against the surface of the rolls, the cracks, pit-marks, scratches, etc., are smoothed out at the point of go pressure during every revolution of the rolls and a substantially smooth and unmarked surface is continually presented to the metal being rolled. Generally speaking, the present invention contemplates applying sufiicient pressure to the surface of rolls din-ing rolling operation to substantially close and smooth out surface flaws during every revolution of the rolls.

It is convenient to apply the pressure of the hardened rod or the like to the surface of the rolls on a line parallel to the longitudinal axis of the roll. Thus, a hard metallic rod of small diameter may be forced to bear a uniform pressure on the surface of the roll at all points along a line parallel to the main axis of the roll.

A preferred embodiment of the present invention is shown in Fig. 1 and on a larger scale in Fig. 3, in which reference character 5 represents a metallic roll used, for instance, for the production of metallic strips directly from molten g metal. Bearing against the surface of the roll 5 is a cylindrical rod 6 of hard metal which extends across the entire rolling surface of the roll and exerts a uniform pressure at all points of contacts thereof.

Cylindrical rod 5 is forced against working roll 5 by floating rolls 1A and 1B which are backed up by a cluster of three rollers 8A, 8B and 8C rotatably mounted on sliding block 9. Housing II, which is preferably maintained in a fixed relation with respect to working roll 5, guides the motion of sliding block 8 in a direction perpendicular to the surface of roll 6. The motion of block 5 is controlled by screw ll mounted in housing II and engaging sliding shoe I 2 which contacts at its lower surface I! the upper surface 5' of block I on a place which is slightly inclined to the direction of screw I I. As more clearly shown in Fig. 4, shoe i2 is provided at either side of its lower surface with inclined flanges I! which are engaged by guides l4 mounted on either side of inclined surface 5 of block 9. By turning screw ll, shoe I! may be made to move laterally in either direction and cause sliding block 9 to be displaced radially either towards or away from roll 5, thereby controlling the pressure between rod 5 and roll I. For convenience in dismounting the smfacing device, guides ii are preferably made detachable, for instance, by bolting them on surface 9' of block 9.

A uniform pressure normal to working roll 5 is produced by so placing middle roller 83 in relation to rod 8, that a line passing perpendicularly through the central axis thereof is normal to the surface of roll I, while rollers 8A and 80, as well as rolls TA and 1B, are symmetrically arranged one on each side of the aforementioned perpendicular line. In order to maintain floating rolls 1 and cylindrical rod 6 in position, rolls 1 are preferably smaller in diameter than rollers 8 and larger than rod 5, while the central axes of rolls I are made to lie above lines joining the centers of roller 8A and rod 6, and the centers of roller 86 and rod 6 respectively, and below lines joining the centers of rollers 8A and 8B and 8B and 80 respectively.

A method of supporting rollers 8 in block 8 is shown in Fig. 2, and more in detail in Fig. 4. Any number of sets of rollers I may be provided, and for the purpose of obtaining a more uniform pressure along the face of the working roll 5, the rollers may be mounted on several sliding blocks with separate adjustments. For instance, as shown in Fig. 2, 6 sets of rollers 8 and 3 sliding blocks 9 may be provided, each block controlling 2 sets of rollers.

Of course, the invention is capable of other embodiments and other methods may be employed for producing a uniform pressure on the surface of the working roll capable of smoothing out and closing surface imperfections of the roll. For example, cylindrical rod 6 may be con- 1 nected directly to block 9, may be of larger diameter, or may be a stationary smooth surface and to provide devices for compensating for simple harmonic motion due to vibration. Thus, as shown in Fig. 1, housing Ill for the surfacing device of the present invention is supported by hydraulic cylinders i5 mounted on frame l8, which may be fixed to the housing of rolls 5 in any conventional manner. One or more cylinders i5 may be provided to support housing In. For instance, housing Ill may be supported at both ends thereof I DA and i013 by a pair of hydraulic cylinders which may be mounted one on each side of the housing of rolls 5. It is to be observed that by supporting the surfacing device on hydraulic cylinders variations of excentricity are allowed for and a substantially uniform pressure of rod 5 may be maintained against the surface of rolls 5. Of course, instead of hydraulic cylinders coil springs and similar devices may be employed which allow for variation of excentricity and maintain a substantially uniform pressure of the surfacing device against the surface of rolls 5. Similarly, other convenient methods may be employed of supporting housing III as hydraulic cylinders or similar devices hereinabove described. It may also be desirable to provide for cooling the surfacing device, or parts thereof tending to become hot in service, for instance, by an appropriate system of water cooling, which may be connected to the cooling system of the working rolls.

In carrying the present invention into practice, for instance, in the process of producing a solid strip directly from molten metal, rolls 5 are rotated to eject a solid strip through the bight thereof at the desired rate. The surfacing devices are then adjusted so that cylindrical rods stresses, which are mainly due to the alternate in heating and cooling of the rolls as each portion of the surface thereof comes first in contact with molten metal by which it is heated to relatively high temperature and then in contact with cooling water by which it is again cooled down to a lower temperature. The heating of the rolls when in contact with the liquid nietal may cause cracking, etc., on the surface thereof. When first formed, these fire-cracks are usually very small and are located just at the surface of the 2 rolls. If left uncorrected, however, the initial fire cracks, scratches, pit-marks, etc. grow larger by fatigue under the alternation of heating and cooling stresses at every revolution of the rolls.

By means of the present invention, however,

not only fire-cracks, but pit-marks, scratches and all other surface defects are immediately corrected and smoothed out by the pressure exerted on the roll surface by the surfacing device described hereinabove.

It was found that by applying pressure on the rolling surface not only are the surface defects thereof corrected. but the surface is also maintained in a hardened smooth condition and therefore more resistant to wear.

It is to be observed that according to the principles of the present invention, the flaws are substantially removed immediately after they have been formed by closing them by appropriate tools exerting a pressure on the surface of the rolls. Preferably the flaws are removed without taking ofi or removing any material fromthe roll. The process can be carried out in different ways, for example. by hammering, pressing, rubbing, rolling and the like.

It is to be observed that by means of the present invention, that portion of the rolls coming in contact with the metal being formed or rolled is kept in substantially smooth condition at all times during the rolling operation, and, (3011589 quently, the rolled metal is produced free from roll marks.

It is further to be noted that the present invention practically eliminates the necessityv of frequent. expensive and time-consuming dressing operations to remove surface defects which are formed on the rolls during operations.

Furthermore, by practically eliminating grinding, the present invention increases the working life and reduces the maintenance charges on rolls, and makes it possible to use the rolls during their full life substantially without any interruptions.

Moreover, it is to be observed that the present invention provides a roll surfacing device which is simple, economical, efficient and which can be 3 comprises a set of working rolls and means coacting with said rolls and capable of exerting against the working surface thereof sumcient pressure to smooth out and-close surface flaws substantially during every revolution of said rolls.

2. An apparatus for continuously surfacing rolls during the working operation thereof which comprises a set of rolls for forming sheets from molten metal, compression means coacting with theworking surface of said rolls, and means for controlling the pressure of said compression means against the working surface of said rolls whereby surface flaws thereof are substantially smoothed out and closed substantially during every revolution of the rolls.

3. An apparatus for continuously surfacing rolls during the working operation thereof which comprises a set of rolls for forming sheets from molten metal, compression means coacting with the working surface of said rolls, means for removably mounting said compression means on the supporting frame of said rolls, and means for controlling the pressure of said compression whereby sur ace fiaws thereof are substantially smoothed ou and closed substantially during every revolution of the rolls.

4. An apparatus for continuously surfacing rolls during the working operation thereof which rollsduring the working operation thereof which comprises a set of rolls for forming sheets from molten metal, compression means coacting with the working surface of said rolls, means for removably mounting said compression means on the supporting frame of said rolls, means for controlling the pressure of said compression means against the working surface of said rolls whereby surface flaws thereof are substantially smoothed out and closed substantially during every revolution of the rolls, and means for water cooling said compression means connected to the cooling system of the working rolls.

6. An apparatus for continuously surfacing rolls during the working operation thereof which comprises a frame, a set of rolls mounted in said frame for forming sheets directly from molten metal, a compression roller coasting with the working surface of said rolls and removably mounted on the frame of said rolls, and means for controlling the pressure of said compression roller against the working surface of said rolls whereby the surface flaws thereof are substantially smoothed out and closed substantially during every revolution of the rolls.

'7. An apparatus for continuously surfacing rolls which comprises a frame or set of rolls mounted in said frame for forming sheets directly from molten metal, a compression roller coasting with the working surface of said rolls, means for fioatably holding said roller against the working surface of said rolls and removably supported on the frame of the'rolls, and means for controlling the pressure of said compression roller 1 means against the working surface of said rolls against the working surface of said rolls whereby the. surface flaws thereof are substantially smoothed out andclosed substantially during every revolution of the rolls.

8. An apparatus for continuously surfacing rolls which comprises a set of rolls for forming sheets directly from molten metal, a rotatable. flexible, hardened, small metallic rod coacting with the working surface of said rolls, means for removably mounting said rod on the supporting frame of said rolls, and means for controliably compressing said rod against the working surface of said rolls whereby the surface flaws thereof are substantially smoothed out and closed substantially during every revolution of the rolls.

9. An apparatus for continuously surfacing rolls which comprises a supporting frame, a set of rolls mounted in said frame for forming sheets directly from molten metal. a rotatable flexible hardened steel rod of small diameter coacting with the worlnng surface of said mils, means for floatably holding said rod against the working surface of said rolls, means for mounting said holding means on 'the supporting frame of'said rolls, and means for controlling the pressure of said rod against the working surface of said rolls whereby the surface flaws thereof are substantially smoothed out .and closed substantially during every revolution of the rolls.

10. An apparatus for continuously surfacing rolls during the working operation thereof which comprises a set of rolls for forming sheets from molten metal, compression means coacting with the working surface of said mils, hydraulic cylinders for mounting said compression means on the supporting frame of said rolls, and means for controlling the pressure of said compression means against the working surface of said rolls whereby surface flaws thereof are substantially smoothed out and closed substantially during every revolution of the rolls. a

11. An apparatus for continuously surfacing rolls which comprises a set of rolls for forming sheets directly from molten metal, a rotatable, flexible, hardened, small metallic rod coacting with the working surface of said rolls, hydraulic cylindersfor mounting said rod on the supporting frame of said mils, and means for controllably compressing said rod against the working surface of said rolls whereby the surface flaws thereof are substantially smoothed out and closed substantially during every revolution of the rolls.

12. An apparatus for continuously surfacing rolls which comprises a supporting frame, a set of rolls mounted in said framefor forming sheets directly from molten metal, a rotatable flexible hardened steel rod of small diameter coacting with the working surface of said rolls, means for floatably holding said rod against the working surface of said rolls, yieldable means for mounting said holding means on the supporting frame of said rolls, and means for controlling the pressure of said rod against the working surface of said rolls whereby the surface flaws thereof are substantially smoothed out and closed substantially during every revolution of the rolls.

13. An apparatus for surfacing relatively large metal work rolls in a mill without substantially removing metal from the surface of said work metal from said work roll, and

roll which comprises a hardened pressure roller having an extremely small diameter with respect to the diameter of said work roll and extending acres practically the entire working surface of said.work roll, and a cluster of -backing up rolls to force said hardened pressure roller against the surface of said work roll, said apparatus being capable of being mounted in operative association with said rolls without disturbing the normal operation thereof.

14. An apparatus for surfacing relatively large metal work rolls in a mill wlthout'substantially re.- moving metal from the surface of said work roll which comprises a hardened pressure roller having an extremely small diameter with respect to the diameter of said work roll and extending across practically the entire working surface of said work roll, a cluster of backing up rolls to force said hardened pressure roller against the surface of said work roll, means for supporting and housing said hardened pressure roller and said cluster of backing up rolls, and means for removably moimting said housing on said mill containing said work mils, said apparatus being capable of being mounted in operative association with said rolls without disturbing the normal operation thereof.

15. The method of surfacing relatively large metal work rolls of rolling mills for forming metal sheets which comprises rotating said relatively large work rolls, rolling against said work rolls a hardened metallic rod having an extremely small diameter with respect to the dimeter of said work roll and extending across practically the entire surface of said work roll, and controlling the pressure applied to said hardened rod to substantially smooth out and 'close surface flaws of said work roll without removing substantially any metal therefrom.

16. The method of continuously surfacing relatively large work rolls in a mill for forming metal sheets directly from molten metal which comprises rotating said relatively large work mils to eject solid metal, subjecting the surface of said relatively large work roll to the action of a hardened metallic rod having an extremely small diameter with respect to the diameter of said work roll and extending across practically the enth'e face of said work roll, and adjusting the pressure of said hardened rod against said work roll to substantially smooth out and close surface flaws in said work roll during every revolution thereof without substantially removing any metal from said work roll.

17. The method of continuously surfacing relatively large work'rolls in a mill for forming metal sheets directly from molten metal which comprises rotating said relatively large work rolls to eject solid metal, subjecting the surface of said relatively large work roll to'the action of a hardened metallic rod having an extremely small diameter with respect to the diameter of said work roll and extending across practically the entire face of said work roll, adjusting the pressure of said hardened rod against said work roll to substantially smooth out and close surface flaws in said work roll during every revolution thereof without substantially removing any effecting cooling of said hardened rod.

CLARENCE W. HAZELEIT.