Circular saw leveling and tensioning machine

Abstract

A circular saw blade straightening and tensioning machine has a set of straightening and tensioning rollers on both sides of a saw blade. The rollers are mounted on parallel shafts. Each shaft has a hub at its end, comprising a center portion horizontally eccentric with respect to the center line of the shaft, and a pair of side portions disposed on opposite sides of the center portion. Each of the side portions is horizontally eccentric with respect to the shaft center line, but in a direction opposite to that of the center portion. A roller is rotatably mounted on each of the center and side portions of the hubs. An actuator rotates each of the upper and lower shafts selectively ninety degrees in both the clockwise and counterclockwise directions. Rotation of the shafts selectively force a center roller against one surface of the saw blade while simultaneously forcing the side rollers against the other surface of the saw blade, thereby to level deformations in the blade. Rotation of the shafts in opposite directions forces the center rollers on both shafts against both surfaces of the saw blade, thereby to tension the blade. A sensor includes a movable foot pivotably mounted intermediate four fixed foot supports. The movable foot carries a gauge that measures the deviation underneath the movable foot from the plane determined by the fixed supports.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, and particularly to FIG. 1, the circular saw leveling and tensioning machine 40 of the present invention includes a cabinet 42 having a frame or base plate 44 on which the principal components are mounted. A circular saw blade 46 is mounted on a vertical powered arbor 48 that is rotated clockwise (as indicated by arrow 50 in FIGS. 2 and 9) through a variable speed drive and reduction gear 52 by a motor 54. An encoder 56 (see FIGS. 8 and 28) tracks the saw rotation location.

A roller slide carriage assembly 58 is mounted on a plate 60 mounted on frame plate 44 and is designed to carry a straightening and tensioning press 62. The set press 62 is adapted to be disposed on both sides of saw blade 46 and carries two sets of rollers 64 on axes 66, 68, which are themselves concurrent with a radius of blade 46. A scanner carriage assembly 70 carrying a sensor 72 is also mounted on frame plate 44 and is adapted to move sensor 72 along a saw radius ninety degrees in advance of press 62. Sensor 72 is adapted to generate a signal to press 62 in the event of unevenness in saw blade 46 in either the upward or downward directions.

Roller Carriage Assembly

Roller carriage assembly 58 (the "first carriage") and press 62 are more fully illustrated in FIGS. 2, 3, 4, 5 and 6. As set forth hereinabove, and as clearly shown in FIG. 3, roller carriage assembly 58 is mounted on plate 60, which itself is mounted on frame plate 44. Carriage assembly 58 carries press 62 with rollers 64 along a radius of blade 46 ninety degrees in advance of sensor 72. A ball screw or threaded spindle 74 (FIG. 4) is rotatably mounted in supports 76 and is driven by a motor 78. Carriage 58 includes a plate 80 (FIG. 5) from which depends an internally threaded nut 82 that receives spindle 74 and by which plate 80 and carriage assembly 58 are driven selectively inwardly and outwardly (back and forth) along the radius of saw blade 46. Plate 80 also carries depending brackets 84 that ride on rails 86 mounted in supports 76, as shown.

As hereinabove mentioned, press 62 includes two sets of rollers 64, a set of upper rollers 88 and a set of lower rollers 90. Upper rollers 88 are mounted on an upper shaft 92, whose axis is axis 66. Lower rollers 90 are mounted on a lower shaft 94, whose axis is axis 68. Upper shaft 92 is mounted in an upper shaft housing 96, being rotatably supported by bearings 97. See FIG. 6. Lower shaft 94 is mounted in a lower shaft housing 98 and is similarly supported. See FIGS. 3 and 5.

Lower shaft housing 98 is attached to a "first arm," which comprises a plate 100 carried by lower arms 102, 103 pivotally mounted to carriage plate 80 in pivots 104. See FIGS. 2, 3 and 5. The pivoting action, which will be hereinafter described, permits the lower set of rollers 90 to be lowered from and raised to their working elevation.

A pneumatic cylinder 106 (FIGS. 3 and 5) is mounted on plate 100 by bolts 108. Cylinder 106 includes a piston 110 having a piston rod 112. A threaded adjustment bolt 114 screws into the lower end of rod 112 and is held in an adjustable desired position by a lock nut 116, as shown. Adjustment bolt 114 bottoms or sets on plate 80. In operation, pneumatic pressure introduced at 115 causes piston rod 112 and adjusting bolt 114 to extend, thereby to rotate plate 100 and arms 102, 103 to raise lower shaft 94 and its rollers 90 to their working position adjacent the lower surface of saw blade 46. This actually provides a small clearance 117 between rollers 90 and saw blade 46. See FIGS. 5 and 13. Cylinder 106 is single-acting so that when the air pressure is turned off, gravity alone lowers the assembly approximately three-quarters inch from its illustrated position to permit a saw blade to be placed in position. See FIG. 12. The pressure that accomplishes raising of the lower roller assembly to its working elevation is preferably adjustable to ensure a "soft" position.

Upper rollers 88, upper shaft 92 and upper shaft housing 96 are supported in a similar manner by a "second arm," which comprises a plate 120, which itself is carried by a pair of upper arms 122, 123 hinged, respectively, to the lower arms 102, 103 at hinge points 126. See FIGS. 1, 2, 3 and 5.

Lower arm 102 extends upwardly in an "L"-shaped configuration, achieving an extension 128, as clearly shown in FIG. 5. An adjustment bracket 130 is bolted to extension 128 by bolts 132, 134, bolts 134 being received in a slotted hole 136 to permit rotational adjustment by adjusting screws 138. This allows a desired small clearance 139 to be set accurately between upper rollers 88 and saw blade 46. The adjustments on bolt 114 for lower arms 102, 103 and for adjusting screws 138 for bracket 130 need be set only one time and thereafter can be left alone.

Adjustment bracket 130 is also formed in a generally "L"-shaped configuration such that it can support an upper pneumatic cylinder 140 having a piston 142 and piston rod 144. Upper cylinder 140 serves two main purposes: when the lower end is pressurized at 146 and the upper end is exhausted at 148, upper rollers 88 are raised for saw change access. See FIG. 12. When the upper end 148 is pressurized and the lower end 146 is exhausted, piston rod 144 is extended to its full length, as shown in FIGS. 5 and 13. In this position, the small clearance 139 is achieved between upper rollers 88 and saw blade 46. Thus, when both cylinders 106 and 140 are fully pressurized, such that their respective piston rods 112 and 144 are fully extended, the same small clearances 139 and 117 occur between the upper and lower sets of rollers 88, 90 and the upper and lower surfaces of saw blade 46, respectively. See FIGS. 3, 5, 11 and 13.

Straightening and Tensioning Rollers

The design and function of the upper and lower sets of rollers 88, 90 are a principal feature of my invention. Referring particularly to FIG. 6, each of upper and lower shafts 92, 94 (FIG. 6 illustrates upper shaft 92 and its rollers 88 only, lower shaft 94 and its rollers 90 being the same) is attached at its outer end to a double eccentric cam hub 150 by a key 152, spacer 154, and nut 156, as shown. Each hub 150 includes a circular center portion 158 whose center line 159 is horizontally offset or eccentric with respect to axes 66, 68 of shafts 92, 94. Each hub 150 also includes a pair of circular side portions 160 that are disposed on opposite sides of center portion 158 and whose center lines 161 are horizontally offset or eccentric with respect to axes 66, 68, but in a direction opposite to that of center portion 158.

Upper and lower roller sets 88, 90 each comprise three pressing rollers, all having the same outer diameter, a center roller 162 mounted on hub center portion 158, and two side rollers 164 mounted on side portions 160, all of which rollers rotate on bearings 166, being retained on hub 150 by a shaft nut 168, as shown. FIG. 6, a horizontal section, illustrates hub 150 and rollers 162, 164 in their neutral or zero position, whereby the rollers appear as shown in FIGS. 2, 3, 5, 9, 11, 12 and 13, that is, with the aforementioned small clearances 139, 117 between them and the upper and lower surfaces of saw blade 46. Bearings 166 may desirably comprise an SKF 6011 for center portion 158, and an SKF 6009 for side portions 160.

As will hereinafter be more fully explained, upper and lower shafts 92, 94 are adapted to be rotated selectively ninety degrees clockwise and counterclockwise from their zero position through couplings 169 by pneumatic rotary actuators 170. When actuators 170 rotate a shaft ninety degrees, depending upon the direction, either the center roller 162 or the two side rollers 164 will protrude such as to have positive contact with saw blade 46. (Clockwise and counterclockwise herein refer to the rotation of shafts 92, 94 as viewed from the ends to which actuators 170 are coupled.)

As an example of its leveling operation, if sensor 72 detects an upward protrusion in saw blade 46, as the saw blade passes roller set press 62, upper and lower roller sets 88, 90 are actuated by their respective actuators 170 to rotate shafts 92, 94 counterclockwise such that center roller 162 of upper set 88 is forced downwardly a distance exceeding clearance 139 and, simultaneously, side rollers 164 of lower set 90 are forced upwardly a distance exceeding clearance 117, thereby causing a downwardly bending pressure on the upward protrusion. See FIGS. 15 and 19. If, however, sensor 72 detects a dent or a downward deformation in the upper surface of saw blade 46, actuators 170 rotate shafts 92, 94 in the opposite direction, that is, clockwise, resulting in an upward bending action. See FIGS. 14 and 18. If an adjustment to plate tension is needed, actuators 170 rotate upper shaft 92 counterclockwise and lower shaft 94 clockwise, such as to cause both center rollers 162 to exert pressure on saw blade 46, thereby causing the metal to be compressed. See FIGS. 16 and 20.

Actuators

Actuators 170 are schematically illustrated in FIG. 7. An actuator suitable for use with this invention is a three-position actuator manufactured by Schrader Bellows®, Rotary Actuator Division, 135 Quadral Drive, Wadsworth, Ohio 44281, whose published catalog material is herein incorporated by reference. Such an actuator includes four ports 171, 172, 173, 174, as shown, and further includes an upper rack 176 and a lower rack 178. Racks 176, 178 are actuated by pistons 181, 182, 183, 184 to rotate a pinion 186 clockwise or counterclockwise, as indicated by arrows 188, 190. A solenoid (not shown) connects ports 171, 172, 173,174 to a source of pneumatic pressure.

Pressurizing actuator ports 171, 173 with ports 172, 174 connected to exhaust, causes clockwise pinion rotation such that upper and lower shafts 92, 94 achieve the positions illustrated in FIGS. 14 and 18. Alternately, energizing the solenoid oppositely pressurizes actuator ports 172, 174 with ports 171, 173 exhausted, thereby causing counterclockwise pinion rotation such that upper and lower shafts 92, 94 achieve the positions illustrated in FIGS. 15 and 19. The neutral or zero position is illustrated in FIGS. 13 and 17.

Scanner Carriage Assembly

Scanner carriage assembly 70 (the "second carriage") and sensor 72 are fully illustrated in FIGS. 1, 2, 3, 9, 10 and 11. Scanner carriage assembly 70 comprises a scanner carriage 192 having a base plate 193 and is mounted on a base 194 comprising a pair of rails 196, themselves mounted in end brackets 198 attached to frame plate 44 by bolts 200. Rails 196 constitute a track, which makes an angle of ninety degrees with respect to the axes 66, 68 of roller set 62 sets 64. Inasmuch as saw blade 46 rotates clockwise, orienting the scanner carriage track in advance and at ninety degrees with respect to the direction of motion of the scanner carriage assembly 70, achieves a ninety degree programmable time lapse from the time a deformation is detected by sensor 72 until the two sets of rollers 64 react.

A bent arm 202 is attached to the upper part of carriage 192 by brackets 204 and bolts 206. See FIG. 11. Sensor 72 is attached to arm 202 such that it can travel along a radial path ninety degrees in advance of the path traveled by scanner carriage assembly 70.

A second arm 208 is also attached to scanner carriage 192 by a bracket 210 and bolts 212. Arm 208 is positioned immediately below arm 202 and is adapted with post 218 to support saw blade 46 when the saw is thin enough to require it. Specifically, an extension arm 214 is attached to the end of arm 208 by a bolt 216 and carries a vertically oriented post 218 whose position is adjustable with respect to extension 214 by lock nuts 220. See FIG. 11.

Sensor 72 and post 218 can both be raised and lowered with respect to the position of saw blade 46 as required for loading, operating, etc. A pneumatic cylinder 222 (FIG. 10) attached to base plate 193 has a rod extension 224 that contacts a rocker arm 226, which is attached to arm 202 by a key 228 such that rocker arm 226 can rotate arm 202 to raise sensor 72, as required. See FIG. 11. A limit rod 232 is also attached to base plate 193 and is held in adjustable position by a nut 233. Limit rod 232 is provided to restrict the rotation of rocker arm 226 and thus, to restrict the amount of upward travel of sensor arm 202 and sensor 72. When rocker arm 226 is level, as shown in FIG. 10, cylinder 222 is in its retracted position, rod extension 224 is in its adjusted position to contact rocker arm 226 to float sensor 72 on the top of saw blade 46, and limit rod 232 is also in its adjusted position, to limit the travel of rocker arm 226 to facilitate saw replacement.

Raising and lowering arm 208 and post 218 is accomplished in a similar manner. Referring to FIGS. 2, 9 and 10, a cylinder 234, a rod extension and a limit rod (neither of the latter being shown) are provided similar to cylinder 222, rod extension 224 and limit rod 232, respectively, except that they act on a rocker arm 236, which is attached to arm 208 by a key 238, as shown. The rod extension and limit rod for rocker arm 236 are, of course, shorter than rod extension 224 and limit rod 232. Also, it should be noted that the working position of arm 208 is when it is in its raised position (see FIG. 11), whereas arm 202 supporting sensor 72 is in its operating position when it is in its lowered position.

Sensor

The design and function of sensor 72 is another principal feature of my invention. Sensor 72 is best illustrated in FIGS. 24 and 25, although it is also illustrated in FIGS. 1, 2, 3, 9 and 11. Its operation is illustrated in FIGS. 21, 22, 23 and 27. A prior art sensor is illustrated in FIG. 26.

As shown in FIGS. 3 and 11, an extension 240 is attached to the end of arm 202 by bolts 242, sensor 72 being slidably retained in extension 240 by a screw 244, which passes through a clearance hole 246. Hole 246 allows sensor 72 to have total freedom to float while in contact with saw blade 46; however, screw 244 permits sensor 72 to be lifted from saw blade 46 by arm 202 and extension 240 when required. See the phantom line position of sensor 72 in FIG. 11.

Sensor 72 itself comprises a body or frame 248 (see FIG. 24), which is preferably rectangular in shape, and has four flat, fixed, foot supports 250 for sliding along the upper surface of saw blade 46. The contact surfaces of supports 250 define a perfectly flat plane. A rotatable arm 252 is pivotally mounted at pivot points 253 in frame 248 and carries a fifth flat foot 254. Foot 254 contacts the upper surface of saw blade 46 intermediate supports 250 and along a radius of saw blade 46. By this means foot 254 can measure any deviation from the flat plane defined by the positions of supports 250 as saw blade 46 rotates beneath sensor 72. Supports 250 and foot 254 are provided with carbide wear surfaces where they contact saw blade 46.

As shown in FIGS. 3, 11, 24 and 25, frame 248 is also attached to depending flanges 255 of arm 202 by a pair of chains 256, one being attached to each side of frame 248. See FIG. 25. Chains 256 accurately move sensor 72 radially along saw blade 46 when sensor 72 is in its down or working position, but they hang loosely when arm 202 raises sensor 72, as shown in phantom in FIG. 11.

A sensor gauge or switch 258, which may be a Micro Switch™ No. 924AB3H-L2P, and which includes a transducer, is mounted in an end 260 of pivotal rotatable arm 252. As hereinabove mentioned, switch 258 measures upward and downward deviation of movable foot 254 from the plane defined by the four fixed foot supports 250 and generates a signal through wire 262 proportional to such deviation.

As schematically illustrated in FIG. 28, when switch 258 receiving power from a power supply 259 detects a deviation from the aforementioned flat plane, and which deviation exceeds a predetermined amount, a signal is transmitted to an analog input 263. The signal feeds the information to a programmable logical controller 264, which may be an Allan-Bradley PLC Model SLC 500, although other PLCs and/or computers could be used. Controller 264 is programmed by an input card 265 from manual inputs I_M, as shown. Controller 264 signals actuators 170 through an output card 266 to rotate rollers 88, 90 to exert upward or downward pressure on saw blade 46 as required. Encoder 56, which may be an Allan-Bradley Absolute Optical Position encoder, Model No. 845-SJDZ-24-AN-CW5, also provides information to controller 264 through an encoder card 267. Such information relates rotation of saw blade 46, movement of roller carriage 58, and corresponding movement of scanner carriage 70, as will hereinafter be discussed.

As is evident, my sensor does not have to be calibrated for each saw blade thickness, as is necessary with sensors that are referenced from a fixed beam and have a single-point sensor pin. Also, because my supports 250 and movable foot 254 have large carbide wear surfaces, they have a very long life cycle. In contrast, a single-point sensor pin has a very tiny contact, which makes it vulnerable to wear-related errors. Also, sensor 72 is able to recognize a properly tensioned saw blade, even though such may sag at its periphery when lying horizontally and supported only at its eye. My sensor recognizes this as a function of tension, and my rollers react accordingly. On the contrary, a sensor referenced from a fixed beam and having a single-point sensor pin detects such a sagging saw blade as having a very long, downward deformation, thereby to provide erroneous information to deformation-correcting rollers.

Operation of my sensor is illustrated in FIGS. 21, 22, 23 and 27. Referring to FIG. 21, sensor 72 is illustrated in contact with a perfectly flat, circular saw blade 46. Movable foot 254 is, accordingly, positioned within the flat plane defined by the positions of supports 250. Switch 258 measures a gap 268 and references it as normal or zero deformation. Switch 258, accordingly, sends no signal to actuators 170.

FIG. 22 illustrates sensor 72 in contact with saw blade 46 when deformed upwardly. Movable foot 254 is raised with respect to the flat plane defined by the positions of foot supports 250 and, accordingly, rotates arm 252 upwardly about pivot points 253. This results in an enlarged gap 269. Switch 258 then signals actuators 170 to exert downward pressure on saw blade 46. This, of course, occurs after the expiry of the period of time corresponding to the length of the circular path between the point at which sensor 72 detects the increased gap and the point of contact of the sets of rollers 88, 90.

FIG. 23 is a similar view illustrating sensor 72 in contact with a saw blade 46 deformed downwardly. Switch 258 reacts to a reduced gap 270 and transmits a signal to actuators 170 to rotate roller sets 88, 90 to exert upward pressure on saw blade 46 at the expiry of the aforementioned period of time.

As has been mentioned hereinabove, a typical deformation in a saw blade is often a combination of three bends. For example, a bulge in an upper surface of a saw blade is often the result of two concave deformations, which result in a convex deformation between them, when viewed from above. In many such cases, only the concave areas are the actual defective areas, the convex area being the natural result of the concave areas on either side. Such a condition is schematically illustrated in FIG. 26.

FIG. 26 illustrates a prior art sensor 271 referencing from a fixed beam and having a single-point sensor pin 271a. Such a sensor only triggers the leveling process when a deformation exceeds a certain limit. In the FIG. 26 illustration, the actual concave portion of the deformation identified "A" will be undetected, as will the concave portion identified as "C," and sensor 271 will only call for correction in the apparently convex area identified as "B." sensor Sensor 271 cannot identify deformations in areas "A" and "C" and calls for rollers to work only area "B," whereas in the FIG. 26 example, such working is actually unneeded.

Referring to FIG. 27, in contradistinction to the ability of single-point sensor 271, sensor 72 of the present invention detects area "A" as concave, area "B" as convex, and area "C" as concave, and then works each of them accordingly.

As previously mentioned, another problem for a single-point sensor is that of plate thickness. A single-point sensor and sensor 72 of the present invention both require a saw blade to be supported from below. However, when a single-point sensor is calibrated, as it must be, for a certain plate thickness, for example, 0.100 inch, and a saw blade of a different thickness is installed, for example, 0.125 inch, the pin 271a will sense the thicker plate as having a continuous 0.025-inch upward deformation. Such, of course, results in a totally erroneous action in leveling the saw.

Roller Carriage-Scanner Carriage Connection

It is axiomatic that the center of movable or pivotable foot 254 and the mid-planes of rollers 162, 164 must always be located on the same circular line of saw blade 46, notwithstanding that the radii on which they act are ninety degrees apart. That is, roller sets 64 and sensor 72 must be displaceable by the same distance toward the center or toward the periphery of saw blade 46 at all times.

The means by which I tie roller carriage 58 and scanner carriage 70 together are best illustrated in FIGS. 2, 3, 4, 8, 9 and 11. Specifically, I utilize two sections of roller chain 272, 274, a pair of attached coaxial sprockets 276, 278, and a pair of idler rolls 280, 282. As shown in FIGS. 4 and 5, a bracket 284 is mounted beneath roller carriage plate 80, to which bracket 284 the ends 286, 288 of chain 272 are attached. Chain 272 is entrained around sprocket 276 and idler roll 280. See FIGS. 2, 4, 8 and 9. Chain 274 is entrained around sprocket 278 and idler roll 282. Also see FIGS. 2, 4, 8 and 9. Coaxial sprockets 276, 278 are attached to each other as above mentioned and rotate on a shaft 290 in bearings 292 attached to frame plate 44. See FIG. 8. Thus, movement of roller carriage 58 along threaded spindle 74 by motor 78 causes chain 272, idling on idler 280, to rotate sprocket 276 and attached sprocket 278.

Chain 274 is attached at its ends 294, 296 to a bracket 298 depending from base plate 193 of scanner carriage 70. See FIGS. 9, 10 and 11. Thus, movement of roller carriage 58 by rotation of spindle 74 causes chain 272 to rotate sprocket 276, which causes an identical rotation of sprocket 278. This rotates chain 274 around idler roll 282 to move scanner carriage 70 a distance identically equal to the movement of roller carriage 58. This ensures that movement of threaded spindle 74 will cause rollers 162, 164 and the center of pivotal foot 254 to occupy the identically same radial position on saw blade 46 at all times.

As shown in FIG. 8, encoder 56 is mounted on the bottom of shaft 290, being rotated by sprockets 276, 278. Shaft 290, with its bearings 292, thus effectively ties sprockets 276, 278 together with encoder 56. A torque arm 299 is attached at one end 300 to encoder 56 by bolts 302 and at its other end 304 to a bracket 306 by a bolt 308. Bracket 306 is, in turn, attached by a bolt 311 to a vertical plate 310 depending from frame plate 44. This prevents the body of encoder 56 from turning while shaft 290 rotates. Encoder 56 tracks the location of rollers 162, 164 and sensor 72 with respect to a radius of saw blade 46 and feeds the data back to controller 264. The data is also used as limits for the total travel of the machine, as well as each saw configuration.

More specifically, encoder 56 outputs electrical pulse signals which controller 264 tracks. Through the tracking of these "pulses", controller 264 learns the exact rotational position of sprockets 276, 278 and shaft 290. Since sprockets 276, 278 and shaft 290 are connected to roller carriage 58 and scanner carriage 70 by roller chains 272, 274, controller 264 knows the exact positions of the carriages at all times. Such positioning information is used for a number of different purposes which are all controllable by controller 264. Examples of such purposes are to determine inner and outer travel limits of carriages 58 and 70; to trigger the beginning point at which to commence leveling and tensioning; and to read the advance distance and speed of each consecutive rolling pass.

As is evident, the required beginning point and ending point will vary from one saw diameter to another. One of the manual inputs (see FIG. 28) is a selector switch (not shown) which the operator sets to match the particular saw to be worked. Such selection sets all the applicable parameters for controller 264 as programmed for the particular saw blade.

Using information from the selector switch, controller 264 establishes the various pneumatic pressures for cylinder 140. Such information is sent from controller 264 to a MAC® proportional control valve (not shown). Controller 264 first reads the position from the selector switch that identifies the saw. That information is then combined with the programmed data for the pneumatic pressure settings for cylinder 140. Using the data from encoder 56 and the deformation information from sensor switch 258, controller 264 signals the proportional control valve to set the pressure in cylinder 140 as required for the stepwise operation to remove unevenness in the saw blade as will be hereinafter explained.

Stepwise Operation

Elimination of deformations or unevenness in a saw blade 46 is typically achieved by my machine in a series of steps, generally three steps. FIG. 29 illustrates, schematically and greatly exaggerated, a deformation like that illustrated in FIGS. 26 and 27, and which is reduced in a series of three steps, or stages. FIG. 30 is a diagram illustrating how correction is achieved in each of the three steps, or stages.

I first note that there is a relationship between the displacement (depth or height of a defect) and the voltage V put out by sensor 72. This is set forth in the left-hand column of FIG. 30. It is also necessary to establish the voltage generated by a perfectly flat, level saw. The calibration that establishes this level is the basis for the entire leveling operation. It varies from machine to machine and is dependent upon the installed position of sensor 72 at assembly. FIG. 30 illustrates the value of that voltage by the horizontal line L.

As illustrated in FIG. 30, stepwise correction of deformations is achieved in a series of three passes. These are controlled by selector switches S₁, S₂, and S₃, as shown. In the first of such steps, "Rough" leveling R, controller 264 ignores all voltages within a programmable, relatively wide range from the calibration point illustrated by the "fixed adjustment" or the voltage established for a perfectly flat, level saw. That range is the "Null" range or window N_R shown in the "Rough" line R in FIG. 30. Only voltages above the "Null" window N_R cause controller 264 to fire rollers 162, 164 to press an upwardly extending deformation down. This is shown by the symbol P_DR. If the voltage falls below the "Null" window N_R, controller 264 fires rollers 162, 164 to press a downwardly extending deformation up. This is shown by the symbol P^UR. In the "Rough" step R, controller 264 is programmed to fire or provide the highest, preestablished air pressure in upper pneumatic cylinder 140. See FIG. 5. Such pressure establishes the maximum force that arm 122 can exert on rollers 64. While in this "Rough" mode R, all lesser displacement defects, i.e., those within the "Null" window N_R, are ignored.

When the "Rough" cycle R is completed, the leveling proceeds to the mid-cycle shown in the middle line M in FIG. 30. The "Null" window N_M is reduced, whereby the machine works defects of lesser magnitude. For this step, controller 264 is programmed to provide a lesser predetermined pressure in upper cylinder 140.

When the mid-cycle is completed, the leveling proceeds to the "Finish" leveling step F shown at the right of FIG. 30. The "Null" window N_F is reduced even further. Pneumatic pressure in upper cylinder 140 is reduced again, and the deformation is reduced to its final tolerance T_F.

It should be noted that the cycles referred to hereinabove are completely controllable by the controller 264. I have found that the application of working pressure by means of rollers 162, 164 in three steps generally achieves desired saw blade surface quality and within a reasonable time.

Consider now a deformation of the type shown in FIGS. 26, 27 and 29, wherein concave areas "A" and "C" create a convexed area "B," as shown. If sensor 72 detects a concave defect, whether it be a defect "A" or "C" leading into a convex defect "B," or the center or main portion of a low dent (area "B" in a diagram like FIGS. 26, 27 or 29 but drawn upside down), sensor 72 first reads the voltage, which is a function of the amount of displacement. See left-hand column R of FIG. 30. In the first cycle, which is the "Rough" benching, controller 264 provides the previously described predetermined high pressure to upper cylinder 140 (FIG. 5), which pressure stays constant during the entire roughing cycle. If the voltage shown in the left-hand column of FIG. 30 drops to less than the preprogrammed "Null" limit for the "Rough" cycle, controller 264 fires rotary actuators 170 to cause upper side rollers 164 and lower center roller 162 to contact saw blade 46 with a bending force limited by the pressure in upper cylinder 140. Saw blade 46, of course, is rotating, and at the end of each revolution, controller 264 causes rollers 64 and sensor 72 progressively to index to a new radial position on saw blade 46. This continues until the entire surface of saw blade 46 is covered. The "Rough" cycle is then completed, and controller 264 starts the next cycle.

If during the next cycle sensor 72 again detects a concave defect, again whether it be a defect "A" or "C" leading into a convex defect "B," the center or main portion of a low dent (area "B" in a diagram like FIGS. 26, 27 or 29 but drawn upside down), sensor 72 again reads its voltage, which indicates its displacement. In this second cycle, which is the aforementioned mid-cycle or "Medium" benching, controller 264 provides the aforementioned medium predetermined air pressure to upper cylinder 140, again maintaining this medium pressure during the entire "Medium" or mid-cycle. If the voltage from sensor 72 drops to less than the preprogrammed "Null" limit in this mid- or "Medium" cycle, actuators 170 are fired to cause upper side rollers 164 and lower center roller 162 to contact saw blade 46 with a bending force, again limited by the pressure in cylinder 140. Saw blade 46 is continually rotating, and at the end of each revolution, rollers 64 and sensor 72 are progressively indexed to the next radial position on saw blade 46. After the entire surface of saw blade 46 is covered, controller 264 starts the third and final cycle.

The operation of my machine for the third or "Finish" cycle is exactly the same as for the previous two cycles, except that the "Null" limit is narrower, representing the final tolerance as shown, and the air pressure in cylinder 140 is lower such as to obtain a considerably lessened roller pressure.

Where a dent occurs in the opposite direction, that is, a convex defect, whether it be a convex area leading into a low dent (imagine FIGS. 26, 27 or 29 drawn upside down), or the center or main portion of a high dent, sensor 72 again reads its voltage, which is above the established "Level" voltage (shown in FIG. 30), and which is a function of the amount of displacement. In the first cycle, again the "Rough" benching cycle, controller 264 provides air to upper cylinder 140 at the predetermined high pressure. The pressure remains at this level during the entire roughing cycle. If the voltage from sensor 72 increases to more than the preprogrammed "Null" limit, actuators 170 are fired to cause the lower side rollers 164 and the upper center roller 162 to contact saw blade 46 with a bending force limited by the pressure in cylinder 140. Saw blade 46 is rotating, and at the end of each revolution, rollers 64 and sensor 72 progressively index to a new radial position on saw blade 46. When the "Rough" cycle is completed, controller 264 starts the next cycle.

If during this next cycle a convex defect is detected by sensor 72, whether it be leading into a low dent or is itself the main portion of a bulge or high dent, sensor 72 reads its voltage, which is an indication of displacement. In this second cycle, which is the "Medium" benching, controller 264 provides air pressure to cylinder 140 at the predetermined medium pressure, which remains at this level during the entire "Medium" cycle. If the voltage from sensor 72 increases to more than the preprogrammed "Null" limit in this "Medium" or mid-cycle, actuators 170 are fired to cause lower side rollers 164 and upper center roller 162 to contact saw blade 46 with a bending force limited by the pressure in cylinder 140. Saw blade 46 is continually rotating, and at the end of each revolution, rollers 64 and sensor 72 progressively index to the next radial position on saw blade 46. At the completion of this cycle, controller 264 starts the next, final or "Finish" cycle.

The "Finish" cycle is exactly the same as the "Rough" and "Medium" cycles, except that the "Null" level is narrower, representing the final tolerance as shown, and the pressure in cylinder 140 is lower, achieving the lesser roller pressure.

As described, my machine achieves these cycles in steps, first "Rough" and then progressively working to the "Finish" benching cycle. A deformation having a total amplitude 312 as shown in FIG. 29 is reduced in the "Rough" cycle to amplitude 314, then by the "Medium" or mid-cycle to an amplitude 316, and finally, by the "Finish" cycle to the final tolerance, represented by the dotted line 318. Roller action, that is, firing to push a dent or concave area up or push a bulge or convex area down, is done on demand, as called for by sensor 72. The action occurs very rapidly. For example, the deformation illustrated in FIG. 27 would require rollers 162, 164 to fire up, then to fire down, and finally to fire up, all this occurring in the length of time it takes to pass between the upper and lower sets of rollers. In actuality, the way cycles are determined and the number of cycles desired to constitute a complete leveling job are programmable in the controller 264, as the user prefers.

In view of the variations that can be made in my invention, I intend that my invention is not to be limited to the exemplary embodiment herein depicted and described in detail, but only by the following claims.