US3207013A

US3207013A - Refinishing of worn rolls

Info

Publication number: US3207013A
Application number: US170689A
Authority: US
Inventors: Ponnath Hans
Original assignee: HUETTEN und BERGWERKE RHINEHAU
Current assignee: HUETTEN und BERGWERKE RHINEHAU; HUETTEN- und BERGWERKE RHINEHAUSEN AG
Priority date: 1962-02-02
Filing date: 1962-02-02
Publication date: 1965-09-21
Anticipated expiration: 1982-09-21

Description

Sept. 21, 1965 H. PONNATH REFINISHING 0F WORN ROLLS 5 Sheets-Sheet 1 Filed Feb. 2, 1962 Hons Ponnorh BY ATTORNEYS Sept. 21, 1965 H. PONNATH 3,207,013

REFINISHING OF WORN ROLLS Filed Feb. 2, 1962 5 Sheets-Sheet 2 Hans Ponnufh BY PM W MEW; 71 a ATTORNEYS Sept. 21, 1965 H. PONNATH REFINISHING OF WORN ROLLS 5 Sheets-Sheet 3 Filed Feb. 2, 1962 lNVl-NTO/P H on 5 Po n norh BY fl w W MLW /W ATTORNEYS United States Patent 3,207,013 REFINISHING 0F WORN ROLLS Hans Ponnath, Rheinhausen, Germany, assignor to Huettenund Bergwerke Rhinehausen Aktiengesellschaft, Essen, Germany, a Germancompany Filed Feb. 2, 1962, Ser. No. 170,689 5 Claims. (CI. 82-14) In the rolling of metals into rolled shapes, there are employed rolls having grooves in the surface thereof, shaped and dimensioned to define the cross section to be given to the material to be rolled. The rolls therefore possess along their length portions of unlike diameter or caliber, and the trace of the surface of such a roll in a plane containing its axis may be referred to as the profile of the roll. The material to be rolled is passed through a succession of stands of such rolls having suitably graduated profiles in order to give the material the desired shape after the proper number of passes. In general, the profiles of these rolls are made up of straight or curved lines of various inclinations to the roll axis, and the surface of such a roll may be regarded as composed of surfaces of revolution generated by these lines. These various surfaces on the rolls are subjected to unlike amounts of stress in use and therefore they wear at unlike rates. In consequence, the profiles of the rolls, and their calibers, change with use to such an extent that the rolls finally become unuseable. They can however be restored to the useable condition by turning them down in a lathe. This requires removal in the turning operation of whatever material is required to restore the original profile.

The amount of material which must be so removed depends upon the maximum wear which has occurred at any point on the profile of the roll. Since generally each roll includes a plurality of portions of unlike diameter or caliber, the turning operation is conditioned by that portion of the roll which has undergone the most wear. That is to say, the portion of the roll which has undergone the most wear determines the radial extent of the cut which must be effected over the entire surface of the roll in order to restore eits original profile.

In order to identify this region of maximum wear, it is necessary to measure each portion of the roll of distinct diameter and to determine from the measurements so made where the maximum wear has occurred. This measuring operation, when performed by hand, is tedious and is subject to error on the part of the operator. For simplicity, it has heretofore been customary to take only sample measurements at randomly selected points and then, for the sake of safety, to increase arbitrarily the amount of the cut to be made above that indicated by the maximum amount of wear indicated by these measurements.

In this operation as heretofore performed it has been customary to employ templates of sheet form made of steel or of synthetic material. It has been necessary for these templates to be accurately finished and accordingly the manufacture thereof has been costly.

By means of the present invention these difficulties in the process of reworking rolling mill rolls are overcome. By means of the present invention it is possible to rework such rolls with a minimum of effort and with removal of a minimum of material.

According to the present invention the roll to be reworked is first measured. The results of these measurements are then recorded on a suitable record medium such as a magnetic or punched tape or the like. The measured values so recorded are then compared with data representative of the desired profile, likewise recorded on a similar record medium, i.e., with data repre- 3,207,013 Patented Sept. 21, 1965 sentative of the original profile of the roll which is to be restored thereto by the refinishing process of the invention. The departures of the actual roll measurements from the intended or desired ones are then computed by means of a computing device. These departures are then employed to determine that shift of the desired values which, upon recording on a new record medium of the desired values so shifted, will effect such a control of the cutting tool in the turning operation as to reduce to a minimum the amount of material which must be removed from the roll being reworked or refinished. In the turning operation of the worn roll the cutting tool is then moved relative to the work in a manner known per se in the operation of program-controlled machine tools.

More particularly, the amount of material to be removed is reduced by determination, for example with the aid of a computer, of a least maximum difference, or amount of departure, between the desired and actual roll measurements as a function of relative axial shift of the actual and desired profile data. This least maximum difference is determined by effecting an axial shift of the schedules of actual and desired diameters for the entire roll relative to each other in an amount c0rresponding to this least maximum difference.

According to a further feature of the invention, a further reduction in the amount of material to be removed is achieved by effecting each portion of the roll having a separate diameter or set of diameters a separate axial displacement of the actual value diameter measurements of that portion with respect to the desired diameter values of that portion by an amount producing a least maximum difference between those actual diameter measurements and those desired diameter values as so shifted.

Adjustment of the record medium bearing the data for control of the cutting tool in the lathe to the ap propriate axial displacement as determined by the computer can be effected by hand in a known manner. Since the rolling process requires at least two rolls, it is necessary in each instance to determine as between the rolls which Work together the one whose profile has suffered the most wear. The least maximum departure between the actual diameter of this roll and the diameters scheduled for it by the process of the invention serves to control the cutting tool in reworking all rolls employed in a single pass of the material being rolled, whether this least maximum departure is computed on the basis of a single axial shift of the complete actual and desired roll profiles or on the basis of separate shifts for the various portions thereof.

Further details of the invention will be explained with reference to the accompanying drawings in which:

FIGURE 1 is a diagram illustrating control of a lathe for the refinishing of a roll, the cutting tool of the lathe being controlled by means of a signal representing a schedule of desired diameters recorded on a magnetic tape;

FIGURE 2 is a diagrammatic representation of a scanning device for the determination and recording of the extent of wear of a roll as a preliminary to its being refinished;

FIGURES 3a to 3e are curves useful in explaining the invention; and

FIG. 4 is a block diagram further illustrating that step in the process of the invention whereby there is determined the optimum axial shift of the desired profile before the desired profile so shifted is reworked onto the roll; and

FIG. 5 is a block diagram illustrating the reworking of the roll to the desired profile so axially shifted.

Referring now to FIG. 4 there is shown a block diagram of apparatus by means of which, from a scanning of the worn roll as in FIG. 2, there is determined the optimum.

axial shift of the desired profile which permitsthe roll to be reworked to that profile with minimum radial out.

In FIG. 4 the scanner 4 mounted on carriage 13 is seen to move longitudinally of the roll by operation of lead screw 22 and transversely thereof by operation of crossscrew 28. The ways 24 in which lead screw 22 is journaled and held against lengthwise motion and which guide the carriage 26 in lengthwise motion have been omitted from FIG. 4 for clarity. The scanner may be moved longitudinally at an arbitrary slow rate and the scanner 4, responding to varying contact pressures between the stylus 5 and the roll, cause-s the transverse lead screw drive motor M to execute motions as required to maintain the stylus in contact with the roll. For this purpose the scanner and the transverse lead screw drive motor are connected into a conventional closed servo loop which may include an amplifier as shown at 99. The scanner 4 develops electrical signals which indicate the magnitude and sign of the departure of the stylus from a selected contact condition with the roll (eg a particular value of stress or pressure between the stylus and the roll), and these signals are employed via the amplifier 99 to energize the motor M in the direction and amount required to restore the stylus to proper contact with the roll, all in accordance with conventional servo practice.

For example, the stylus 5 may be resiliently mounted by means of springs 60 to possess an equilibrium position with respect to the cross-slide carriage 13 and to be movable parallel to the cross-slide screw 28 out of that equilibrium position in response to engagement with the roll. One conventional form of apparatus for generating signals representative of departures of the stylus from this equilibrium position is indicated in FIG. 4. Fixed to the stylus is the primary winding 62 of a transformer energized from a suitable A.C. source, not shown. Adjacent to the primary winding 62 are two secondary windings 64 and 66, fixed with respect to the carriage 13 and oppositely wound with respect to each other. For the equilibrium position of the stylus, equal and opposite voltages are induced in the secondary windings 64 and 66 and the algebraic sum thereof perceived in the servo amplifier 99 is zero. Departures of the stylus from this equilibrium position in one or the other direction will produce as the sum of the voltages in windings 64 and 66 a net voltage of amplitude representative of the amount of the stylus departure from equilibrium position and having a 180 phase relation with respect to the energizing voltage in winding 62 which indicates the sense of the stylus departure from equilibrium position.

The transverse lead screw drive motor M develops sig nals representative of actual cross-slide position and hence of scanner position, for example with the aid of conventional means such as a helical potentiometer coupled to motor M and these signals representative of actual crossslide position and hence of actual roll diameter are delivered to a recording device 100 which may incorporate the magnetic head 6 of FIG. 2. There are also delivered to the recording device 100 signals representative of the longitudinal position of the scanner, these signals being those by means of which the longitudinal lead screw drive motor M is controlled for longitudinal drive of the scanner.

The data on actual roll diameters as a function of position along the roll thus recorded in the device 100 is the data of curve 7 in FIG. 3b. It is therefore a record of variations in the actual diameter of the roll, referred to the diameter of the roll at the lands thereof such as 36, 38, 40 and 42. The record may take the physical form of a magnetic tape as shown at 10 in FIG. 2.

A storage device 102 contains a record of desired diameters, again as a function of position along the roll. The data on the record in device 102 is the data of curve 2 as shown in FIG. 3a and constitutes therefore a record of the desired variations in the diameter of the roll, referred to the diameter thereof at the

lands

36, 38, 40 and 42.

Acomputer 104, which may be conventional in nature and of either analog or digital type, operating on the data recorded in device 100 and on the data recorded in device 102, subtracts the ordinates of curve 2 in FIG. So from the corresponding ordinates of curve 7 in FIG. 311. More particularly, the computer 104 performs this subtraction for each of a plurality of relative axial, positions of the curves 3a and 3b, selecting that relative axial position for which the differences exhibit the least maximum value. Determination of this axial shift giving least maximum difference is readily performed since with conventional apparatus the taking of the differences for a single axial shift requires only a very short instant of time..

Referring now to FIG. 5, there is shown a signal generating device 108 which contains a program of the desired r-oll diameters, and more particularly a program. of the desired variation in roll diameters referred to the lands on the desired roll surface, this program of desired roll diameters being axially shifted with reference to the position ,of that program as shown in FIG. 3a by the axial shift which has been determined in accordance with the operations described in conjunction with FIG. 4. The device 108 delivers this program of axially shifted desired diameters to the cross-slide drive motor M and simultaneously it delivers to the longitudinal lead screw drive motor M signals representative of the successive axial positions to which the cross-slide positions so delivered to M correspond. In this way the cutting tool of FIG. 5 is caused to rework the roll to its original profile, with minimum radial cut by virtue of an axial shift of the desired profile, all in accordance with the invention.

For the refinishing of a roll according to the invention, it is first necessary to compare the original profile of the roll with that of the roll as worn.

In order to record the actual profile there may be employed, as indicated in FIGURE 2, a scanning device 4 mounted on the cross slide 13 of a lathe whose ways are shown at 24. The scanning device 4 may be electric or electronic in nature. The stylus 5 of the device 4 executes a motion, composed of very small steps, which closely follows the actual profile of the roll 20. From this motion the device 4 develops signals corresponding to the profile of the roll, of varying duration, which are transmitted to the lead screw 22 for lengthwise motion of the carriage 26 and to the cross screw 28 for motion of the cross slide 13. This process corresponds to the scanning of a template or of a sample in a copying lathe. Axial motion of the scanner is effected by means of a motor M operating on the lead screw of the lathe, and cross motion is effected by means of a motor M operating on the cross screw.

The motions of the lead screw and cross screw are communicated to a storage device, for example via a magnetic recording head 6 and are recorded on a magnetic tape 10 or other suitable record medium of the storage device. The record may be in either digital or analog form. A two-dimensional graphic representation of this record has been superposed on the tape 10 in FIGURE 2 in the form of the curve 7 which is drawn with reference to axes of ordinates and of a-bscissae y and x. The axis y represents inverse radial position from the axis of the roll 20 and the x axis represents axial position lengthwise of the axis of the roll. That is, increasing values of y represent positions closer to the roll axis. In similar fashion there is recorded on the same record medium i.e. on the tape 10 (for example in a separate track thereon) a set of signals representative of the desired roll profile. This desired profile is shown in the two-dimensional graphic representation of FIGURE 2 at the dash line curve 2.

the tape in FIG. 2. In FIGURE 3a, the curve 2 repre sents the desired profile for the roll, i.e. that which it possessed when new, whereas in FIGURE 3b the curve 2 has superposed thereon the curve 7 representative of actual roll profile.

The difference y y represents the amount of wear which the roll has undergone, measured radially, and this difference is plotted in FIGURE as a function of axial position x lengthwise of the roll, where it is seen to have a maximum value indicated at 9. If the roll were to be turned down without axial displacement of the profile, it would have to be turned to reduce its radius throughout its length by the amount 9 from the original value of that radius in order to restore the original profile. This is illustrated in FIGURE 3d, where a radial displacement of the amount 9 between the curve 2 representing the original profile and the curve 12 representing the desired profile is seen to be just sufficient to provide clearance between the actual profile 7 and a reproduction, as at 12, of the original profile.

In accordance with the invention instead, the intended profile indicated at 12 in FIGURE 3d is subjected in the computer to an axial shift x to a new position indicated at 12a. As a result of this shift the maximum radial separation of the actual profile 7 from the intended profile 12a (which is a reproduction of the original profile 2) is reduced from the amount 9 to the amount 9a. This shift is effected in the computing machine and the curve 12a thus obtained serves to control the cutting tool in the tuming operation by which the roll is reworked. That is, the curve 12a represents the profile which the cutting tool imparts to the roll in the refinishing process of the invention. It is to be emphasized that the data representative of the actual and desired profiles need not be stored in the form of a curve. Representation thereof in the form of curve has been employed only for the sake of clarity. The mode of storage and of computing are dependent on the nature of the computer employed.

In the modification of the invention illustrated in FIG- URE Be there is computed for each portion of the roll having a distinct diameter or set of diameters such an axial shift of the actual and desired profiles of that portion with respect to each other as to result in a least maximum radial separation of the actual and desired profiles for that portion. The largest of these least maximum values may then be selected to specify the reduction be ow the original profile radius to be effected over the whole length of the roll in refinishing it.

More particularly it will be observed that the profile of FIGURE 3a comprises three

portions

30, 32 and 34 limited by

lands

36, 38, 40 and 42 on the surface of the roll. No rolling action takes place at these lands, as indicated by the absence of wear there in FIGURE 3b. In other words, the curves 2 and 7 of FIGURE 3b coincide at these lands. Consequently, the curve 8 of FIGURE 30 is made up of three parts, 44, 46 and 48 of non-zero value.

Curves

44, 46 and 48 are plots of the wear at

roll portions

30, 32 and 34 respectively, and each has a separate maximum. These maxima are shown at 33, 9 and respectively. As already stated, if the roll is to be refinished with its profile 2 in the same axial position on the roll as originally, the turning operation will have to reduce the radius of the roll everywhere by the amount 9 below the original radius value. If, in accordance with the method of the invention explained in connection with FIGURE 3d, the entire schedule of desired diameters represented by curve 2 or 12 in FIGURES 3a or 3d is shifted as a unit with respect to the schedule of actual diameters represented by curve 7 in FIGURE 3b, the curve 8 of FIGURE 3c will have, for such an axial shift in the amount x a different shape whose maximum ordinate is the amount 9a of FIGURE 3d, and this maximum is less than the maximum assumed by the curve 8 (of altered shape) for any other axial displacement of the curves 2 and 7.

In accordance with the particular form of the method of the invention illustrated in FIGURE 3e, the roll is refinished with the

profile portions

30, 32 and 34 in altered relative axial positions, with a separate axial shift for each, and the radial cut made in the refinishing operation is determined as the largest of the least maxima found for

curves

44, 46 and 48 individually by axially shifting separately the schedules of diameters for

profile portions

30, 32 and 34 with respect to the schedules of measured diameters of those portions respectively.

For the portion 30, the least maximum ordinate of curve 44 occurs with an axial shift as indicated at 17 in FIGURE 3e; for portion 32 the least maximum ordinate of curve 46 occurs with axial shift 16, and for portion 34 the least maximum ordinate of curve 48 occurs with still another axial shift 19 of portion 34. The largest of these three least maxima is indicated at 18, which, it will be observed, is substantially less than the amount 9a of FIGURE 3d. The roll is refinished to possess the profile 15 of FIGURE 3e which represents the profiles of the three

portions

30, 32 and 34 of FIGURE 3:: shifted axially with respect to their original positions (shown in FIGURE 3a) by the

amounts

17, 16 and 19 respectively and all shifted radially by the amount 18.

Thus the plural axial shifts effected in the method according to FIGURE 3e provide a further means of reducing the amount of material to be removed in refinishing the roll.

FIGURE 1 shows schematically how the roll is turned in accordance with the data so derived. In FIGURE 1, reference character 1 identifies a storage device in which are recorded the

data

12a or 15, according as the roll 20 is to be refinished in accordance with the method described in connection with FIGURE 3d or in accordance with that described in connection with FIGURE 3e. This data is scanned from the record medium 1 by means of a scanning device 3. Control signals developed in the scanner are delivered to the lengthwise and transverse lathe carriage drives M and M for positioning of the tool support 13 and its cutting tool 14 with respect to the roll 20, which is mounted between the live center in the headstock and the dead center in the tailstock (not shown) of the lathe. In FIGURE 2 the roll 20 is also to be understood as mounted between the centers of the lathe.

The invention thus permits reworking of rolling mill rolls with a minimum of cutting.

While the invention has been described in terms of the refinishing of rolls to restore their original profiles thereto, it is not necessary that the profiles to which the rolls are refinished be the same as that originally present thereon.

I claim:

1. A process of refinishing a roll comprising the steps of measuring the diameter of the roll as a function of position along its length, recording the measured diameters on a record medium, recording on a record medium the desired diameters to which the roll is to be refinished, determining as a function of relative axial postion of said recorded measured and desired diameters the least maximum difference between said recorded measured and desired diameters, and turning said roll to a profile defined by said desired diameters axially shifted relative to the profile defined by said measured diameters in an amount corresponding to said least maximum difference.

2. A process of refinishing a roll comprising the steps of measuring the diameter of the roll as a function of position along its length, recording the variations in measured diameters on a record medium, recording on a record medium the variations in desired diameters to which the roll is to be refinished, determining as a function of relative axial position of said recorded variations in measured and desired diameters the least maximum difference between said recorded variations in measured and desireddiameters with an assumed arbitraryradial relation between said measured and desired diameters representative of lands on a common cylindrical surface on said roll, and turning said roll to a profile defined by said desired diameters axially shifted relative to the profile defined by said measured diameters in an amount corresponding to said least maximum difference and radially shifted in the amount of said least maximum difference.

3. A process of refinishing a roll including a plurality of grooves separated by lands disposed on a common cylindrical surface, said method comprising the steps of measuring the diameter of the roll as a function of position along its length, recording on a record medium the departures of said diameters from the diameter of said surface, recording on a record medium the departures in diameter from said surface desired to be imparted to said grooves in refinishing the roll, determining as a function of relative axial position of the said recorded measured and desired departures of said grooves collectively the least maximum difference between said recorded measured and desired departures, and turning said roll to a profile defined by said desired departures axially positioned with respect to said measured departures at the position corresponding to said least maximum difference and radially positioned at a location displaced toward the axis of the roll by the amount of said least maximum difference.

4. A process of refinishing a roll including a plurality of grooves separated by lands disposed on a common cylindrical surface, said method comprising the steps of measuring the diameter of the roll as a function of position along its length, recording on a record medium the departures of said diameters from the diameter of said surface, recording on a record medium the departures in diameter from said surface desired to be imparted to said grooves in refinishing the roll, determining for each of said grooves as a function of relative axial position of the said recorded measured and desired departures of said grooves individually the least maximum differences between said recorded measured and desired departures of said grooves individually, and turning said roll to a profile defined for each of said grooves by the said desired departures thereof individually axially positioned with respect to the said measured departures thereof individually at the positions corresponding to the corresponding ones of said least maximum differences and radially positioned for all of said grooves at a location displaced toward the axis of the roll by the amount of the largest of said least maximum differences.

5. A method of refinishing a roll having lands and worn grooves, said method comprising the steps of measuring the actual variations in diameter of said roll referred to the diameter thereof at said lands as a function of position along the length of said roll, recording said actual variations on a record medium, recording on a record medium the desired variations in the diameter of said roll referred to the diameter thereof at said lands as a function of position along the length of said roll, determining as a function of relative axial position of said actual and desired variations the, least maximum difference between said actual and desired variations, and turning said roll to the profile defined by said desired variations at the axial position for said profile corresponding, to said least maximum difference.

References Cited by the Examiner FOREIGN PATENTS 1,114,501 12/55 France. 1,238,963 7/60 France.

921,791 12/54 Germany.

WILLIAM W. DYER, JR., Primary Examiner.

LEON PEAR, Examiner.

Claims

1. A PROCESS OF REFINISHING A ROLL COMPRISING THE STEPS OF MEASURING THE DIAMETER OF THE ROLL AS A FUNCTION OF POSITION ALONG ITS LENGTH, RECORDING THE MEASURED DIAMETERS ON A RECORD MEDIUM, RECORDING ON A RECORD MEDIUM THE DESIRED DIAMETERS TO WHICH THE ROLL IS TO BE REFINISHED, DETERMINING AS A FUNCTION OF RELATIVE AXIAL POSITION OF SAID RECORDED MEASURED AND DESIRED DIAMETERS THE LAST MAXIMUM DIFFERENCE BETWEEN SAID RECORDED MEASURED AND DESIRED DIAMETERS, AND TURNING SAID ROLL TO A PROFILE