CA2123157A1 - Apparatus for resurfacing cylindrical rolls and a self-servicing roller mill assembled therewith - Google Patents

Abstract

Apparatus for resurfacing a cylindrical roll of a machine that includes the rollas a part of its normal operating equipment, without removing the roll from the machine. The apparatus uses a metal cutting technique rather than a metal abrasion technique. This improves safety by eliminating sparking during resurfacing operations.
The apparatus comprises a cutter head which is reciprocated across the roll on a rail.
The apparatus can be installed as a permanent part of the machine. It is particularly adapted for use with roller mills. The advantage is an economical, safe resurfacing system for cylindrical rolls which obviates a requirement for removing rolls from a mill for resurfacing.

Description

2123~5~

APPARATUS FOR RESURFACING CYLINDRICAL ROLLS
AND A SELF-SERVICING ROLLER MILL ASSEMBLED THEREWITH

Technical Field The present invention relates to mills for comminuting materials, and in particular to an apparatus for resurfacing the rolls of roller mills designed tocomminllte materials.

Ba-~kpround of the Invention Roller mills are widely used for comminuting materials in a broad range of industrial processes. They are also widely used in the food industry to prepare ingredients for food products and to prepare animal rations. Roller mills comminute material by crushing or cutting the material between a pair of opposed rotating rolls supported in an axially parallel relationship to define a small space between the rolls called the "nip". Materials passing through the nip are subjected to the crushing cutting force of the rotating, juxtaposed rolls. In order to facilitate comminlltion, the rolls of a roller mill may be corrugated in a variety of patterns dependent on the desired product.
The rolls of roller mills are commonly made from cast iron which is tempered to a hardness of 48 to 54 Rockwell C. In spite of their hardness, the rolls in a roller mill must be resurfaced periodically, typically every six to eighteen months depending on a variety of factors including the product processed by the mill, the number of hours of operation, and the amount of cont~min~tion such as stones and other foreign matter in the product stream.
Roller mill rolls have been traditionally resurfaced by one of two methods.
Those m:~n~ging small operations commonly remove the rolls from the mill and return them to the manufacturer where they are resurfaced on a lathe or some other precision surfacing instrument using specially constructed grinders for removing surface material.
Those m~n~ging large production operations who cannot afford to shut down while rolls are shipped out for resurfacing either invest in a set of spare rolls which are rotated between production and resurfacing, or hire special service providers who set up grinding equipment to grind the rolls without removing them from the mill.
Grinding rolls in a mill presents two problems. First, expensive equipment and skilled - 212~1~7 operators must be brought in to effect the resurfacing operation. Second, the grinding operation produces copious sparks. Most roller mills are operated in dusty and/or oily environments where sparks are a hazard. It is therefore generally necessary to isolate the mill from the surrounding environment during a resurfacing operation. This is time 5 consuming, disruptive and expensive.
United States Patent 4,707,946 which issued November 24, 1987 to Hirohata teaches a grinding machine that can continuously grind a cylindrical object rotating around its axis supported by a head and tailstock. Grinding tools are attached to a rotating circular plate which is provided on a carriage that moves along a bed adjacent 10 to the axis of the cylindrical object at a constant rate to grind the outer surface of the object. The circular plate includes a front side on which a plurality of first and second grinding tools are mounted. The grinding tools include tools for roughing and tools for fini~hing and are mounted in circular patterns of different radii according to their use in grinding. The plate is moved up and down so that the cylindrical object can be 15 ground with tools relevant to the phase of finishing in progress. The tool holder is reciprocated along the bed by a threaded rod which is rotated by a motor. A nut on the rod urges the tool to slide along the bed. While this apparatus may be suitable for resurfacing smooth rolls removed from a mill, it is not adapted to resurfacing rolls in a mill. Furthermore, it performs a grinding action and therefore produces copious sparks 20 which present a hazard in most environments where roller mills must operate.
C~n~ n Patent Application 2,092,995 was laid-open to public inspection on February 1, 1993 in the name of Farros Blatter AG. This patent application describes a grinder for grinding a cylindrical surface of a roll, especially a paper machine roll.
The grinder is attached to a carriage that is designed to roll along a top of a scraper 25 blade for the roll. The grinder uses a continuous belt abrasive for resurfacing the roll.
Apparently, the roll is rotated at its operating rotation speed while it is ground by the grinder that rides along the top edge of the scraper blade. This ~palaLus could not be used satisfactorily on most roller mills for several reasons. First, the scraper for a roller mill roll is commonly improperly positioned to accommodate a grinder with a 30 large carriage. Second, the configuration of the grinder and carriage would prevent dressing an entire roll in a roller mill because the side panels of the mill would prevent the belt from reaching at least one end of the roll. Finally, the abrasive belt produces copious sparks which are a hazard in most environments where roller mills must operate.
There therefore exists a need for an apparatus which can be used to safely and economically resurface the rolls of roller mills without removing the rolls from the mill.

Summary of the Invention It is an object of the present invention to provide a resurfacer for the rolls of roller mills which minimi7~s the hazards of explosion or fire due to sparks by resurfacing rolls using a metal cutting rather than a metal abrading process.
It is a further object of the invention to provide an apparatus which may be built in to a roller mill as a part of the original equipment that is supplied with the mill.
It is a further object of the invention to provide an apparatus which may be retrofit to a compatible existing roller mill.
It is yet a further object of the invention to provide an apparatus which may beadapted to the resurfacing of smooth rolls and corrugated rolls of a roller mill.
In accordance with the invention, there is therefore provided an apparatus for resurfacing a roll of a roller mill without removing the roll from the mill, comprising in combination:
a rail for supporting a cutting head, the rail being mounted to the roller mill in an axial relationship with respect to the roll of the mill so that a cutting bit mounted to the cutting head is adjustably movable to and from cutting relationship with a surface of the roll;
means for driving the cutting head in a controlled reciprocal movement along the rail to effect the removal of a surface layer of the roll; and means for conkolling rotation of the roll so that a controlled removal of the surface layer is accomplished, whereby the mill may be operated in a normal production mode without removing the apparatus from the mill.
The present invention therefore provides two significant advantages over the prior art. First, it provides a method of minimi7.ing the hazards of resurfacing roller mills in their operating environment by using a metal cutting rather than a metal 2123~57 abrading technique. Cutting bit material is available in diamond, ceramics and ~i~aniu~ll nitrate coated carbides that is capable of cutting 54-56 Rockwell C. tempered ron.
Second, the apparatus in accordance with the invention provides a kit which 5 may be installed in a roller mill as original equipment or retrofitted to existing mills in order to completely elimin~te any requirement for removing the rolls from the mills for resurfacing. This facilitates production, cuts operating costs, and enhances product quality and conserves energy because mill operators are more inclined to keep the rolls of their mills in optimum operating condition.
The apparatus in accordance with the invention comprises a rail for supporting a cutter head. The rail is preferably a square tube which houses a threaded drive rod for the cutting head. The threaded drive rod engages a threaded drive block which reciprocates inside the tube and is in turn attached to the cutter head. The drive rod is rotated by a motor and the rotational movement of the drive rod is translated into 15 reciprocal movement of the cutter head along the rail. The cutter head adjustably supports a cutting bit which is appropliately shaped to resurface a roll of the mill.
The apparatus also includes means for controlling the roll so that the controlled removal of the surface layer is accomplished. The means for controlling the rotation of the roll is dependent on the type of roll which is being resurfaced. In the instance 20 of a flaking mill, the rolls are smooth and the means for controlling the rotation of the roll is preferably a dual speed gear box attached to the main drive motor of the mill, the gear box providing a normal operating speed and a resurfacing speed for the rolls.
The resurfacing speed for the rolls is preferably about 60-80 r.p.m. Alternatively, a hydraulic or an electric gear motor may be attached to the idler shaft for the idler 25 sheave on the roll's drive belts. The motor is adapted to turn the rolls at the optimum speed for resurfacing. The motor idles on the idler shaft at all times when the mill is operating in normal production mode.
If the mill has corrugated rolls, the means for controlling rotation of the roll so that a controlled removal of the surface layer is accomplished is different than30 described above. Corrugated roll mills are resurfaced by reciprocating the cutting head longitudinally of the roll and removing a surface layer of one corrugation with each pass. In order to effectively resurface a corrugated roll, it is essential that the cutting tool be properly indexed with the corrugations in the roll's surface. Indexation is preferably accomplished using al)plo~liately constructed dogs and a ratchet gear affixed to the journal of the roll. The dogs mesh with the ratchet gear to lock the roll in a position appropriate for cutting each corrugation on the roll. Between cuts, a stepper motor or a hydraulic motor advances the roll one notch on the ratchet gear. Each time the cutting head reaches an end of its cutting stroke, it trips a sensor that alerts a controller to release the dogs to permit the roller to advance to the next corrugation to be resurfaced.
Thus, an ~pal~lus for resurfacing the rolls of any roller mill is provided. The apparatus permits the assembly of an improved roller mill that is substantially self-servicing.
Furthermore, the uses of the apparatus is not limited to the resurfacing of roller mill rolls. The a~palalus may be adapted to resurface a cylindrical roll in practically any equipment, including dryer drums, paper machines and the like.
Brief Dcse~ ;I,lion of the Drawin~s The invention will now be further explained by way of example only and with reference to the following drawings wherein:
FIG. 1 is a side elevational schematic view of a typical prior art roller mill construction;
FIG. 2 is a schematic top plan view of the rail and cutter head in accordance with the invention mounted to a bearing housing of a roll of the roller mill shown in FIG. 1;
FIG. 3 is a side elevational view of the apparatus shown in FIG. 2;
FIG. 4 is a cross-sectional view of the rail and the cutter head taken along lines IV-IV of FIG. 2;
FIG. 5 is a partial longitudinal cross-sectional view of the rail taken along lines V-V of FIG. 2;
FIG. 6 is an end elevational view of the cutter head shown in FIG. 4;
FIG. 7 is a cross-sectional view taken along lines VII-VII of FIG. 6;

21231~7 FIG. 8 is a schematic view of an alternate position for mounting the rail and cutter head to a roller mill in order to effect the resurfacing of the drive roll and the driven roll simultaneously;
FIG. 9 is a plan view showing the apparatus for controlling rotation of the rolls of flaking mills to permit a controlled removal of a surface layer to resurface the rolls;
FIG. 10 shows an alternate embodiment of the ~pa dlus shown in FIG. 9, FIG. 11 shows an appaldlus for controlling rotation of a corrugated roll of a rolling mill so that a controlled removal of a surface layer of the roll is accomplished to resurface the corrugated roll.
Detailed DCSL ;~Iion of the Preferred Embodiments FIG. 1 is a schematic side elevational view of a typical prior art construction for a roller mill, generally indicated by the reference 20. Rollers mills invariably include at least two rolls supported in a side-by-side parallel relationship. One of the rolls is known as a drive roll 22 and the other is known as the driven roll 30. The drive roll is rotated by a main drive sheave 24 which is driven by a motor 26, generally an electric motor. A plurality of V-belts 28 encircle the main drive sheave 24 and a motor sheeve 27 (see FIGs. 9-11) in a manner well known in the art. Thedrive roll 22 is provided on each end with a concentric drive roll journal 50. The main drive sheave 24 is affixed to one journal 50 (see FIGs. 9-11) and a drive sheave 32 is affixed to the opposite journal 50. Typically, a plurality of V-belts 38 encircle the drive sheave 32, engage the lower half of a driven sheave 34 which is attached to the driven roll journal 56 and encircles an idler sheave 36. The arrangement of the V-belts 38 turns the driven sheave 34 and the driven roll 30 in an opposite direction to the drive sheave 32 and the drive roll 22. In this illustration, the roller mill is a flaking mill having smooth rollers. Such mills are generally used for processing food and feed products such as flaked grains, etc. Other mills designed for grinding,crumbling or cracking usually have corrugated rolls. The rolls of the flaking mill shown in FIG. 1 are normally driven at the same rate of rotation, so the drive sheave 32 and the driven sheave 34 have the same diameter. Corrugated rolls are normally driven at different rates of rotation in order to accentuate the comminutive action of the rolls. The relative rate of rotation depends on the product being processed. The ~12~157 drive sheave and the driven sheave of a mill with corrugated rolls (not illustrated) therefore generally have different diameters. These principles are well understood in the art.
During the operation of the flaking mill shown in FIG. 1, a product such as 5 whole grain oats is introduced into a feed hopper 40. A feed roller 42 feeds the material to be comminuted 46 into the nip between the drive roll 22 and the driven roll 30. When the material passes between the closely spaced rolls, it is pinched in the nip and flattened. Unless the material 46 is very dry, it generally sticks to the rolls.
Scrapers 48 positioned under each roll scrape the treated material from the rolls where 10 it discharges into a storage bin or a collection trough that feeds an auger (not illustrated) or the like. Roller mills may include up to three or more stacks of the rolls shown in FIG. 1. The construction and operation of roller mills is well known and therefore not explained here in detail.
FIG. 2 shows a schematic top plan view of a rail 58 for supporting a cutter head 60 in accordance with the invention. The rail 58 and cutter head 60 are supported by mounting brackets 62 which are bolted to the drive roller bearing housing 54 that houses the drive roller bearing 52 (see FIG. 3) which supports the drive roll journal 50. The mounting brackets 62 support the rail 58 in a parallel relationship to the axis of the drive roll 22. The cutter head 60 is driven along the rail by a cutter drive motor 92 which turns a bevel gear 91 that meshes with a complementary bevel gear 90 affixed to a drive rod (see FIG. 5). The cutter head 60 is driven reciprocally on the rail 58 while the drive roll 22 is rotated at a speed to permit resurfacing of the roll by a metal cutting operation, as will be explained in more detail with reference to FIG. 5.
FIG. 3 shows a side elevational view of the apparatus shown in FIG. 2. As explained above, the mounting brackets 62 are bolted to the roll bearing housings 54.
The mounting brackets 62 include a plurality of slots 64 which receive drive roll bearing housing bolts 66. The slots 64 permit the mounting brackets 62 to be adjustably positioned relative to the outer circumference of the drive roll 22. Thus, as the drive roll 22 is repeatedly resurfaced, the bracket 62 may be repositioned to permit the cutter head 60 the remove a surface layer from the circumference of the roll.

2~231~7 FIG. 4 shows a cross-sectional view of the drive rail and the drive head taken along lines IV-IV of FIG. 2. The rail 58 is preferably a square tube made of stainless steel, though other materials may also be used. Captured within the rail 58 is a drive block 68 which is threadedly received on a drive rod 70. Each of the drive block 68 5 and the drive rod 70 are threaded in an ACME thread pattern in a manner well known in the art. The rail 58 includes a pair of longitudinal slots 72 and 74 (see also FIG. 5).
The slots accommodate bolts 76 which pass through the slots and connect the cutter head 60 to the drive block 68. The cutter head 60 is secured with set screws 78 to bronze wear plates 80 which slide back and forth along the rail 58 as the cutter head 60 is reciprocated. The bronze wear plates 80 are connected to retainer plates 82 by retainer bolts 84. As can be appreciated, when the drive rod 70 is rotated, the drive block 68 is urged along inside the rail 58. This in turn urges the retainer plates 82 to move along the rail due to the connection of the retainer plates 82 to the drive block 68 by bolts 76. Likewise, the bronze wear plates 80 are urged along the rail due to the connection of the retainer plates 82 to the bronze wear plates 80 by the retainer bolts 84. Thus, as the drive block 68 is reciprocated inside the rail 58, the cutter head 60 is reciprocated along the drive roll 22. This apparatus is equally adapted to be attached in the same manner to the driven roll 30. That attachment is not illustrated but is readily understood because the same principles apply.
FIG. 5 shows a partial longitudinal cross-section of the rail 58 taken along lines V-V of FIG. 3. The drive rod 70 extends completely through the rail 58 and is rotatably supported on each end by roller bearings 86 which are mounted in an end cap 88 that bolts to the mounting bracket 62 (see FIGs. 2 and 3). Affixed to an outer end of the drive rod 70 is a bevelled drive gear 90. A complementary bevelled gear 91 is affixed to the shaft of a cutter drive motor 92 (see FIG. 2). The cutter drive motor 92 may be any suitable reversible motor capable of driving the cutter head 60 along the rail 58 during a resurfacing operation. The cutter drive motor 92 may be a hydraulic motor, an electric gear motor or the like. The direction of rotation of the motor cutter drive 92 is controlled by sensors such as limit switches 102 (see FIGs. 9-11) that sense an end of travel of the cutter head 60, in a manner well known in the art.
FIG. 6 shows an end elevational view of the cutter head 60 removed from the bronze wear plates 80. The cutter head 60 supports a cutting bit 94. The cutting bit - ~1231~7 94 is a triangular bit suitable for fini~hing smooth rolls. The bit is shown in solid lines in a position suitable for resurfacing a single roll. The bit is shown in dotted lines in a position suitable for resurfacing two rolls simultaneously, as will be explained in more detail in relation to FIG. 8. Cutting bits for resurfacing corrugated rolls are shaped to match the corrugation pattern of the roll as will be explained in more detail with reference to FIG. 11.
FIG. 7 shows a longitudinal cross-section taken along lines VII-VII of FIG. 6.
The cutter head 60 includes a base 96 which is connected to the bronze wear plates 80 using set screws 78 (see FIG. 4), a height adjustment section generally indicated by the reference 98 and a bit retainer 100. The height adjustment section 98 includes astationary wedge 102 and an adjustment wedge 104. The adjustment wedge 104 includes an elongated slot 105 which permits the position of the wedge to be changed.
The position of the adjustment wedge 104 is changed within limits by an adjustment screw 106. Moving the adjustment wedge 104 raises or lowers the fixed wedge 102 to raise or lower the cutting bit 94 with respect to the rail 58 (see FIG. 4). A retainer bolt 108 passes through a bore in the base 96, the elongated slot 105 in the adjustment wedge 104, a bore in the fixed wedge 102 and threadingly engages the bit retainer 100 of the cutter head 60. The cutting bit 94 is attached to the bit retainer 100 of the cutter head 60 by a cutting bit retainer screw 110.
FIG. 8 shows an alternate position for mounting the rail 58 and the cutter head 60 to a roller mill. In this position, each of the drive roll 22 and the driven roll 30 can be resurfaced simultaneously. The mounting brackets 62, shown in dotted lines for clarity, are mounted to bores drilled in the side plates (not illustrated for clarity) of the roller mill 20 (see FIG. 1) which support the bearing housings 54 for the drive roll 22 and the driven roll 30. When installed in this position, the cutting bit 94 is inverted so that two cutting edges are simultaneously positioned for resurfacing the rolls simultaneously.
FIG. 9 shows a top plan view of the roller mill 20 shown in FIG. 1 and illustrates one embodiment of the invention for driving the rolls 22, 30 during a resurfacing operation of the rolls. In this embodiment, an idler shaft drive motor 112 is mounted to a free end of the idler shaft 114 that supports the idler sheave 36, the idler shaft drive motor 112 is preferably an electric gear motor although a hydraulic ~12~157 motor may also be used. The idler shaft drive motor 112 should rotate the driven roll 30 and the drive roll 22 at about 60-80 r.p.m. for optimum resurfacing using the cutter head 60 in accordance with the invention. When the idler shaft drive motor 112 is energized, it turns the idler sheave 36 which turns the driven sheave 34 and the drive 5 sheave 32 to rotate the respective rolls. When the mill is in production mode and driven by the drive motor 26, the idler shaft drive motor 112 is de-energized and idles with the shaft.
FIG. 10 shows an alternate embodiment of the invention shown in FIG. 9. In this embodiment, the idler shaft drive motor 112 is replaced with a dual speed gear box 118. The dual speed gear box 118 is adapted to drive the mill in a first gear at the preferred resurfacing speed of 60-80 r.p.m. and in a second gear at the normal operating speed for the mill. The rollers of a flaking mill cannot be resurfaced at the normal operating speed using a metal cutting technique with the cutting bit materials currently available.
A plurality of roll corrugation profiles are commonly used for comminuting material in various industrial processes. A few of the well known roll corrugation profiles f~mili~r to those skilled in the art have been named Lepage, Lepage Ring, Flat Bottom V, Round Bottom V, Sawtooth, Oat Crimper, Dawson, Modified Dawson, Stevens and Ross Flaking Cut. As will be appreciated by one skilled in the art, each 20 profile requires a cutting bit specifically shaped for the profile to be resurfaced.
Cutting bits suitable for resurfacing corrugated profiles may be made by those skilled in the art. The present invention can be used to resurface rolls of any useful profile and is not limited in utility to those profiles listed above.
FIG. 11 shows one embodiment of the invention adapted to resurface the rolls 25 of a roller mill equipped with corrugated rolls. In order to resurface a corrugated roll, it is necessary to index the corrugations of the roll with a cutting bit 94 having a profile that is compatible with the corrugation profile of the roll. The cutting bit is driven longitudinally of the roll along each corrugation in the roll while the roll is held in a stationary position to remove a surface layer of the corrugation and thus renew the 30 corrugation profile. The cutting resistance pressure encountered during resurfacing corrugated rolls will depend on the depth of cut and the coarseness of the corrugation.
Pressures of 75-250 psi are common. The rail 58, the drive rod 70 and the drive block ~l~23 l5~
ll 68 must be constructed to withstand those pressures without deflection or distortion and the cutter drive motor 92 must be sized to provide the required torque.
To control rotation of a roll 22, 30, a dog 124 and ratchet gear arrangement 120 are preferably used in conjunction with a stepper motor installed as the idler shaft 5 drive motor 112. When the cutter head 60 reaches an end of its travel, it activates a sensor 122 such as a limit switch or the like. The sensor triggers a controller (not illustrated) to release the dogs 124 on the ratchet gear 120 and to advance the idle shaft drive motor 112 the proper number of steps to advance the roll to the nextcorrugation. When the dogs re-engage the ratchet gear 120, the controller reverses the direction of the cutter drive motor 92 (see FIG. 3) to drive the cutter head 60 in an opposite direction and resurface the next corrugation on the corrugated roll surface.
The control of the dogs 124 and ratchet gear 120 are well known in the art. The dogs 124 may be controlled by an electromechanical, hydraulic or pneumatic linkage.
Although the apparatus in accordance with the invention has been described 15 with specific reference to roller mills, it will be appreciated by those skilled in the art that it may be adapted to use with practically any machine which includes at least one right circular cylindrical roll, such as a drum dryer, a paper machine and the like.
The preferred embodiments described above are intended to be exemplary only.
Variations of the construction of the described embodiments may be apparent to those 20 skilled in the art. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.

Claims (11)

1. Apparatus for resurfacing a cylindrical roll of a machine which includes the roll as a part of its normal operating equipment without removing the roll from the machine, comprising in combination:
a rail for supporting a cutter head, the rail being mounted to the machine in anaxial relationship with respect to the roll of the machine so that a cutting bit mounted to the cutter head is adjustably movable to and from a cutting relationship with a surface of the roll;
means for driving the cutter head in a controlled reciprocal movement along the rail to effect the removal of a surface layer of the roll; and means for controlling rotation of the roll so that a controlled removal of the surface layer is accomplished, whereby the machine may be operated in a normal production mode without removing the apparatus from the machine.

2. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill, comprising in combination:
a rail for supporting a cutter head, the rail being mounted to the roller mill in an axial relationship with respect to the roll of the mill so that a cutting bit mounted to the cutter head is adjustably movable to and from a cutting relationship with a surface of the roll;
means for driving the cutter head in a controlled reciprocal movement along the rail to effect the removal of a surface layer of the roll; and means for controlling rotation of the roll so that a controlled removal of the surface layer is accomplished, whereby the mill may be operated in a normal production mode without removing the apparatus from the mill.

3. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 2 wherein the rail is a hollow tubular member.

4. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 3 wherein the means for driving the cutter head in a controlled reciprocal movement along the rail to effect the removal of a surface layer of the roll comprises a drive block and a drive rod housed within the rail, the drive rod threadedly engaging the drive block.

5. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 4 wherein the drive rod is rotated by a drive motor affixed to a bracket which supports an end of the rail in an axial relationship with respect to the roll of the mill.

6. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 5 wherein the drive motor is a hydraulic motor.

7. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 5 wherein the drive motor is an electric gear motor.

8. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 2 wherein the mill has smooth surfaced rolls and the means for controlling rotation of the roll so that a controlled removal of the surface layer is accomplished comprises a motor having an output shaft drivingly attached to an idler sheave of the mill roll drive train, the motor being adapted to turn the rolls of the mill at a speed suitable for resurfacing the rolls of the mill during a resurfacing operation.

9. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 2 wherein the mill has smooth surfaced rolls and the means for controlling rotation of the roll so that a controlled removal of the surface layer is accomplished comprises a dual speed gear box attached to an output shaft of the main drive motor for the mill, the gear box being adapted to turn the rolls of the mill at a speed suitable for resurfacing the rolls of the mill during a resurfacing operation, and to turn the rolls of the mill at a mill operating speed when the mill is in normal production mode.

10. Apparatus for resurfacing a roll of a roller mill without removing the roll from the mill as claimed in claim 2 wherein the mill has corrugated rolls and the means for controlling rotation of the roll so that a controlled removal of the surface layer is accomplished, comprises a motor having an output shaft drivingly attached to an idler sheave of the mill roll drive train and a dog and ratchet gear attached to a journal of the roll, the motor being adapted to turn the rolls of the mill one tooth on the ratchet gear when the cutter head trips a sensor indicating an end of travel of the cutting head during an resurfacing operation. so that a next corrugation of the roll is aligned with a cutting bit mounted to the cutter head.

11. Apparatus for resurfacing a roll of a roller mill having smooth surfaced rolls without removing the roll from the mill, comprising in combination:
a hollow rail for supporting a cutter head, the rail being mounted to the rollermill in an axial relationship with respect to the roll of the mill so that a cutting bit mounted to the cutter head is adjustably movable to and from a cutting relationship with a surface of the roll;
a drive block and a drive rod received within the rail for driving the cutter head in a controlled reciprocal movement along the rail to effect the removal of a surface layer of the roll, the drive rod threadedly engaging the drive block so that rotational movement of the drive rod translates to linear movement of the drive block;
and a dual speed gear box attached to an output shaft of a main drive motor for the mill, the gearbox being adapted to turn the rolls of the mill at a first speed so that a controlled removal of the surface layer is accomplished and at a second speed so that the mill may be operated in a normal production mode, whereby the mill may be operated in the normal production mode without removing the apparatus from the mill