US2925691A

US2925691A - Grinding machine

Info

Publication number: US2925691A
Application number: US705614A
Authority: US
Inventors: Edgar D Kibble
Original assignee: MCLOUTH STEEL CORP
Current assignee: MCLOUTH STEEL CORP
Priority date: 1957-12-27
Filing date: 1957-12-27
Publication date: 1960-02-23
Anticipated expiration: 1977-02-23

Description

Feb. 23, 1960 E. D. KIBBLE GRINDING MACHINE 8 Sheets-Sheet 1 Filed Dec. 27, 1957 am um Nah INVENTOR. Ed a? D Jfi'le /3 BY Clif orney.

Feb. 23, 1960 E. D. KIBBLE 2,925,691

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GRINDING MACHINE Filed Dec. 27, 1957 8 Sheets-Sheet 6 INVENTOR.

Feb. 23, 1960 E. D. KIBBLE GRINDING MACHINE 8 Sheets-Sheet 7 Filed Dec. 27, 1957 1 9mm i EwOZ: IO U zonrm QQN v INVENTOR.

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GRINDING MACHINE Filed Dec. 27, 1957 8 Sheets-Sheet 8 STONE MOTORS PUM PS REVERSE ac. POWER PRESSU RES z a g INVENTOR.

E 12 r zaze 2,925,691 GRINDING MAcnmn Edgar D. Kibble, Wyandotte, Mich., assignor to McLouth Steel Corporation, Detroit, Mich, a corporation of Nlichigan Application December 27, 1957, Serial No. 705,614

4 Claims. c1. s1 7s The present invention relates to a grinding machine for preparing slabs or billets or similar bodies of metal for rolling. This invention is particularly useful in connection with the preparation of stainless steel for continuous rolling operations. The ingot is first rolled on a looming or slabbing mill to form a relatively thick slab which is then transferred to a continuous rolling mill. The final product of such rolling operations may comprise a thin sheet of stainless steel having a thickness of only a few thousandths of an inch. In contrast with this the slab may have a thickness of several inches.

It will be appreciated that in rolling operations of this type the surfaces of the ingot are progressively increased in area and that any defects in the original surface will remain and perhaps be greatly exaggerated in the surface of the final product. Thus it is essential to remove insofar as practical, any defects or any layers of metal which differ in an undesirable manner from the remainder of the metal. Experience has revealed that a layer at least about thick should be removed from the sur-' faces of a body of stainless steel preferably when such body is in the form of a slab. The general problem is not unique to stainless steel and is encountered in connection with many metals including various grades of steel. However, the removal of the surface layers of many such metals can be accomplished by scarfing, i.e., by burning away. Stainless steel and various other metals have such characteristics that scarfing is not practical, at least in the present stage of development of such technique. Accordingly, it has become the practice to prepare stainless steel for rolling by grinding the surfaces of the slab. Prior to the present invention such grinding has been performed by snagging grinders in which a grinding wheel is rotated about an axis parallel with the length of the slab. Relative movement is caused between the grinding wheel and the slab in a direction parallel with the length of the slab whereby the grinding wheel will form an elongated groove extending lengthwise of the slab and which is curved in cross-section to correspond with the curvature of the surface of the grinding wheel. Ordinarily only one such snagging grinder is provided and it is necessary to make a great many lengthwise passes forming parallel curved grooves, preferably overlapping one another, so as eventually to grind the entire surface of the slab. When one major surface is thus completed the slab must be turned over to grind the other major surface and again turned twice in order to grind the surfaces of the edges. When it is considered that a slab may be in the order of four feet wide, six inches thick and more than twenty feet long, it will be appreciated that the grinding of successive grooves to cover the entire surface thereof is a slow and tedious operation requiring many hours of labor and utilization of expensive equipment and floor space.

A fundamental objection to the use of snagging grinders is that the finished surface is necessarily made up of a plurality of parallel, inwardly curved grooves which present raised ribs between each groove. In other" Words,

.nitecl States Patent 2,925,691 Patented Feb. 23, 1960 "ice the surface is somewhat corrugated and the thickness of the slab is somewhat irregular, obviously being greater in the region of the ribs and smaller in the region of the bottoms of the grooves. Such irregularity is much increased as the grinding wheels wear inasmuch as the diameter of the Wheels determines the curvature of the grooves. Accordingly, it has not been possible to utilize anything like the entire diameter of grinding wheels used in snagging grinders. This is apparent inasmuch as the use of a small diameter wheel in a snagging grinder would result in the forming of a plurality of closely spaced, sharply curved grooves separated by ribs which tend to fold over in the rolling operation, thus forming a surface defect which is intolerable. At the very best, when wheels of very large diameter are used in snagging grinders, the eventual product varies somewhat in density due to the corrugated surface formed upon the ingot prior to rolling.

The present invention affords a plurality of grinding wheels which rotate upon axes substantially transverse the length of the slab. Such axes may be perpendicular to the length of the slab or they may be slightly inclined thereto so that the debris from the grinding wheel may be discharged over the edge of the slab. The plurality of grinding wheels thus provided are arranged to overlap slightly and they are disposed throughout the width of the slab whereby one entire major surface of the slab may be ground in a single pass through the machine. Preferably each grinding wheel is independently pressed into contact with the surface of the slab under a constant yielding pressure whereby a surface layer of uniform thickness may be removed from the entire surface of the slab irrespective of irregularities in'the shape of the slab. For example, many slabs are warped and it would be extremely wasteful of useful metal to attempt to form a perfectly rectangular structure by planing or grinding flat or true surfaces on the slab. The present invention removes only such surface portions of the slab as must be removed and it forms a uniform smooth surface devoid of ridges or corrugations which surface is highly desirable for the. formation by rolling of thin sheet products having perfect surfaces and uniform density throughout their width.

In the present invention wherein the axes of rotation of the grinding wheels are substantially transverse the length of the slab, each Wheel will grind a stripe having a width substantially equal to the width of the face of the grinding Wheel. Since the width of the stripe is not dependent upon the diameter of the wheel, it will be appreciated that reduction in diameter of the wheel due to wear will have no effect upon the Width of the stripes ground by the wheels. Thus for wheels of a particular width, an arrangement may be made whereby each stripe slightly overlaps the next adjacent stripe and the entire surface of the slab will be ground irrespective of the diameters of the wheels. A very great economy in grinding wheels is thus achieved inasmuch as the wheels may be used down to diameters wholly impractical with snagging grinders. If so desired the wheel speed or speed of feed of the slab or the pressure of the wheel upon the slab may be varied to compensate for the changing diameter of the wheels although such adjustments are not essential to the realization of the major benefits of the present invention.

A preferred embodiment of the invention will be described in detail wherein a Work table is provided with driven rolls for feeding the slab lengthwise with one of its major surfaces disposed upwardly for cooperation with the grinding wheels. Each grinding wheel forms a part of a unit consisting of a motor, driving means connecting the motor with the wheel and hydraulic pressure means for yieldably pressing the wheel downwardly against the surface of the slab under a predetermined constant pressure. Each unit is provided with means for raising and lowering the same to position the surface of the grinding wheel within the operative range of the yieldable pressure applying'means. By this arrangement all of the units may be individually adjusted for 'oper ation upon a slab of a particular thickness to achieve a uniform smooth surface even though the wheels in the different units may be of different diameter due to wear. When a particular wheel is replaced by a new wheel of maximum diameter the particular unit may be raised above the level of other units equipped with wheels of smaller diameter.

it is a feature of the present invention that all of the wheels may be set by appropriate adjustments of the units to operate upon a series of slabs having thicknesses within a particular range. When no slab is in the machine the lower peripheries of all of the wheels will be below a level corresponding to the upper surface of a slab, being urged to such positions individually by their hydraulic pressure-applying means. When a slab is moved lengthwise into the machine the leading end will progressively be forced under the wheels each of which will ride upwardlyover the end of the slab as permitted by the yielding pressure applying means. Such operation is automatic due to the fact that the wheels rotate upon axes generally transverse the axis of feed of the slab and it affords a very great advantage over snagging grinders wherein the edgewise disposed grinding wheel must be raised to clear the end of the slab and then lowered to engage the surface.

The present invention also aifords great flexibility in the spot grinding of surface defects which may remain after a slab has been subjected to the over-all grinding operation discussed above. in such cases all of the units may be raised above operative level and only such units as are needed may be lowered when any such defect,

is brought into an appropriate position for removal.

It is an object of the present invention to provide a grinding machine embodying the desirable features discussed above. Other and further objects will become apparent from the following detailed description of a preferred, but not necessarily the only, embodiment taken 1 in connection with the drawings forming a part of this specification.

In the drawings:

Fig. 1 is a plan view of a continuous grinding machine showing the relative locations of certain broad divisions of the structure of the machine with various parts including the grinding wheels and their supporting cells removed for clarity and convenience in describing the relation of the salient features of the invention to the machine structure as a whole;

Fig. 2 is a side elevational view of the structure of Fig. 1 with the addition of an operators pulpit and a superstructure for supporting grinding units, the lines 1-1 and'associated arrows indicating the aspect of the view of Fig. 1;

Fig. 3 is an enlarged plan view encompassing the region indicated by line 3-3 of Fig. 2, showing the grinding wheels and grid-like supporting structures which define a plurality of cells in which the individual driving motors are mounted;

Fig. 4 is a vertical sectional view taken along line 4-4 of Fig. 3, showing a slab partly in the machine under the first pinch roll and being ground by three grinding wheels, and showing a tie-in mechanism for the control of side guides;

Fig. 5 is a partial horizontal sectional view at the line 5--5 of Fig. 4 showing the side guides and their associated positioning mechanisms, full lines indicating an outer position and dotted lines an inner position, the driving rolls and other portions of the base of themechine being omitted for clarity;

Fig. 6 is an enlarged vertical sectional view taken along line 6-6 of Fig. 5 of one of the side guide cylinders, rack and pinion and tie-in shaft;

Fig. 7 is a vertical sectional view taken along line 7-7 of Fig. 6 showing the rack, pinion shaft and guide means;

Fig. 8 is a typical vertical sectional view through one of the pinch roll resilient bearing guides;

Fig. 9 is a typical vertical sectionalview through one of the pressure roll resilient guides;

Fig. 10 is an enlarged vertical sectional view along line 10-19 of Fig. 3 showing a typical grinder unit assembly in its cell;

Fig. 11 is a side elevational view of one of the grinder unit assemblies with its cell omitted for clarity;

Fig. 12 is a top plan view of a typical grinding unit assembly like that shown in elevation in Fig. 10 and showing a portion of an adjacent grinder unit assembly and the relationship of the grinder units to the work;

Fig. 13 is a horizontal sectional view of a belt takeup mechanism taken along line 1313 of Fig. 11;

Fig. 14 is a schematic diagram of a typical hydraulic system for controlling a typical grinding unit;

Fig. 15 is a schematic diagram of a hydraulic system for controlling various parts of the grinding machine, for example, side guides, pinch rolls and pressure rolls; and

Fig. 16 is a plan view of a control board or console for the machine.

Referring to Figs. 1 and 2, there is shown the general plan and side elevation respectively of a base and supporting structure for a multiple head continuous grinding machine for work pieces such as slabs, billets and the like, embodying the present invention. The machine is shown arranged to feed the work through from right to left. The work, which for illustrative purposes may be a slab of stainless steel, is delivered to the machine by means of a set of power driven entry rolls of which the three nearest to the machine are designated respectively by reference numerals 26, 2'2, 24. After the slab has been ground it emerges from the machine onto a set of power driven delivery rolls of which the three nearest to the machine are designated 26, 28 and 30, respectively. In the machine proper there are shown a plurality of power driven work-advancing rolls or table rolls such as those shown at 32, 34 and36, respectively, of which rolls 32 and 36 are lower members of pairs of pinch rolls. To drivethe plurality of table rolls there is provided a motor 38 connected through a reducing gear box 40 in driving relation to a line shaft 42. Rigidly mounted upon the line shaft 42 are a plurality of bevel gears such as 44, eachsuch bevel gear meshing with a bevel gear rigidly mounted on one of the table rolls, e.g., gear 44 on theline shaft meshes with gear 46 on pinch roll 32. Entry roll 21 is driven by pinch roll 36 as by means of a chain and sprockets. Entry roll 22 is driven by entry roll 20 and entry roll 24 is driven by entry roll 22 in turn by similar suitable means. Likewise, delivery roll 26 is driven from pinch roll 32, delivery roll 28 from delivery roll 26, and so on. Chain drives 48, 50, 52 and 54 are representative, connecting respectively, roll 36 with roll 20, roll 20 with roll 22, roll 32 with roll 26, and roll 26 with roll 28.

Side guides 56 and 58 are shown and are provided with a plurality of hydraulic cylinders, of which cylinder 60 is representative, for adjusting the spacing between the guides in order to accommodate workof various widths and to keep the sides of the work substantially parallel to the longitudinal axis of the machine as the 66 .upon which the operator may stand to operate the achine-;.. A w ns. resn :PEQY df l3l 1gh;

which the operator may watch the progress of the work while being protected from flying particles.

Fig. 3 shows in plan view on an enlarged scale the contents and arrangement of the grinding units carried by the structure 62 in accordance with the invention and portions of the table rolls, side guides, pinch rolls, entry rolls, operators platform, operators console, etc., to show the relationship of the system of Fig. 3 to the machine which is indicated in outline in Figs. 1 and 2.

As may be seen by reference to Fig. 2, the structure 62 is positioned directly above the table rolls in the space between the pinch roll 32 and the pinch roll 36. The view in Fig. 3 is such as is obtained when there is no work-piece in the machine.

Referring to Fig. 3, there are shown

cellular structures

70, 72, each enclosing a motor which drives a belt pulley. Connected to each individual motor by means of a belt is a driven shaft or arbor with a grinding wheel or grindstone rigidly attached thereto. The shafts are of various lengths so that the stones may be applied to a slab or similar work-piece in a staggered diagonal arrangement whereby the entire upper surface of the work may be ground in a single pass through the machine. The respective axes of rotation of the grinding wheels are substantially perpendicular to the line of travel of the work in passing through the machine, or the axes may be rotated at a slight angle to the perpendicular as shown in the drawing. Thus the operation of the wheels is one of grinding as distinguished from snagging. There are fourteen grinding wheels shown in the embodiment represented in Fig. 3. In a machine which has been built embodying the invention, the work may be up to about 53 inches wide, of length up to about 23' feet, and of thickness up to about ten inches. In this case the grinding wheels grind strips approximately four inches each in width and the strips overlap by approximately one-quarter inch. By virtue of the slight angle of departure of the direction of the axis of the grinding wheel from the perpendicular and the staggered arrangement of the wheels, the throwing of material by one wheel into the grinding area of another wheel is minimized. Means is provided as hereinbelow described for maintaining substantially constant pressure between the grinding wheels and the work so as to grind off a substantially uniform layer of material even though the surface of the work may be somewhat uneven or warped as is frequently the case with steel ingots.

A typical motor is shown at 74 (Fig. 3), a typical set of belts at 76, functioning together in place of a single belt. A typical arbor or shaft for a typical grinding wheel 80 is shown at 78. The grinding wheel 80 is enclosed in a protective shield 82. The motor 74 is preferably a DC. motor in order that its speed may be varied in accordance with the reduction in the diameter of the grindstone as the stone wears down. However, a fixed speed motor such as an AC. motor may be used and for simplification of this disclosure the speed con trols which would be used with DC. motors have been omitted. At 34 (Fig, 4) there is shown an upper pinch roll for cooperation with the lower pinch roll 32 and an upper pinch roll 86 for lower pinch roll 36. Pres sure or hold-down rolls 8%, 90, 92 are shown in plan in Fig. 3 and in side elevation in'Fig. 4.

Referring to Fig. 4, a work-piece such as a slab 94 is represented as having been inserted part way into the machine. In the position shown in the figure, the leading edge of the slab has passed over the entry roll 20, between the pair of pinch rolls 36, 86, and is resting momentarily upon the fourth table roll to the left of the pinch roll 36. The work 94 is being held down against the table rolls by the pressure or hold-down roll 92. A grinding wheel 95 is in lowered position and has not yet come in contact with the work. Three other they assume in grinding relation with the upper surface of the work.

A hydraulic pressure cylinder 102 is shown for pressing upper pinch roll 84 resiliently toward lower pinch roll 32 through a relief spring 104. A similar cylinder 106 and relief spring 108 are shown for the pair of pinch rolls 36, 86. Hydraulic cylinders 110, 112, 114, are provided as shown for downwardly urging the respective pressure rolls 88, 90, 92.

Various details of the side guides and the positioning arrangements therefor are shown in Figs. 5, 6 and 7, and details of pinch roll and pressure or hold-down roll assemblies are shown in Figs. 8 and 9 respectively. Further reference will be made to Figs. 4 through 9 hereinbelow after describing more fully the operation of the grinding wheel assemblies.

Referring now to Figs. 10 through 13, there is shown at 116 a fragmentary portion of one of the grid-

like structures

70, 72, which define a plurality of cells, each of which cells is individual to a grinding unit, a typical unit including the grinding wheel together with its associated motor 74, shaft 78, and set of belts 76.

The typical grinding wheel assembly is supported by the base or frame 118 (Fig. 10) of the machine by means of a column such as shown at 120 and a supporting .beam 122. A plurality of columns 120 may support a single beam 122 upon which may be supported all the grinding assemblies for one side of the machine, a total of seven grinding unit assemblies in the embodiment illustrated. A suitable support 124, preferably pivoted as shown, is attached to the upper surface of the beam 122 and has fastened thereto the lower end of a typical hydraulic cylinder 126, which cylinder will be designated hereinafter as the unit cylinder because its function is to raise and lower as a whole the entire grinding unit comprising motor, grinding wheel, etc. The piston 128 of the cylinder 126 is joined, preferably pivotally, by means of a joint 130 to the underside of a motor platform or elevator 132 to which the motor 74 is rigidly fastened. Also attached to the underside of elevator 132 are a plurality of

brackets

134, 136, 138 which support a pivot 140, upon which pivot is mounted a lever-like structure 142. One end of the structure 142 provides journals for the arbor or shaft 78 of the grinding wheel 80. At the opposite end of the shaft 78 from the grinding wheel 80 is fastened a pulley 144. The motor 74 has on its shaft 146 a pulley 148. A belt-tightening idler pulley 150 is also provided, the set of belts 76 serving to connect the motor 74 in driving relation to the grinding wheel 80. The end of the lever-like structure 142 opposite the grinder shaft 78 is attached to a counterweight 152 to facilitate raising and lowering of the grinding wheel according to the requirements of the work, more particularly so that the grinding wheel may rise up over the edge of the work as the leading edge thereof comes in contact with the grinding wheel and so that the grinding wheel may follow surface irregularities of a bent or warped workpiece, for example, or an undulating surface of any kind.

In order to maintain substantially uniform pressure on the grinding wheel, a hydraulic cylinder 154 is provided which is anchored to the underside of the motor platform 132, preferably by a pivoted joint as at 156. The cylinder 154 has a piston rod 158 which in turn is fastened, preferably pivotally, to the lever-like structure 142 as at 160.

The belt-tightening mechanism will now be described in more detail with special reference to Figs. 10, 11 and 13. The belt-tightening pulley 150 is pivotally mounted on a fork-like member 162 which in turn is slidably mounted in a tubular member 164'. A relief spring 166 is confined between the substantially closed lower end of member 164 (Fig. 13) and a shoulder 168 on the forkgrinding wheels 96, 9'8, 100 are shown in the position 75 like member 162 while a rod-like extension of themember 162 extends Within the spring 166 and through a hole 170 in the otherwise closed end of the tube 164 and terminates in a stop 1'72. The tube 164 is rigidly fastened to a stud lldwhich in turn is rigidly fastened to a; link 176. At the end opposite the stud 174, the link 176 ispivotally connected to a stud 178 on a bracket 138. Rotation of the belt-

tightening assembly

150, 162, 164, 176 about the axis of the stud 178 is controlled and restricted by a link 180 extending between a pivotal mounting on the counterweight 152 and another pivotal mounting on an extension of the stud 174-.

When the member 142 rotates clockwise about the pivot 144), thus raising the wheel 80, the counterweight 152 falls and in so doing pulls on the link 189 causing counter-clockwise rotation of the link 176 and tube 164, thereby moving the idler pulley 1S0 toward the right as viewed in Fig. 11 to maintain tension on the belt '76.

202, pinion 204, pinion shaft 192, support 200, and side guide 56. i

Fig. 8 shows a typical resilient bearing guide for a pair of pinch rolls such as 32, 84. The hydraulic cyl-v inder 102 is shown rigidly attached to the frame of the machine at a position above the upper roll 84, with hydraulic connections 2% and 268, respectively, above andbelow the piston within. Attached to the piston rod 211 of the cylinder 102 is a shouldered member 212 which serves to compress the spring 104 thereby transmitting a resilient thrust to a bushing member 214 which in turn urges the pinch roll 84 downwardly to grip the work between the

rolls

84, 32. A tie rod 216 attached When the member 142 rotates counter-clockwise thereby I lowering the wheel 80, the action is reversed and the idler 150 is moved toward the left as viewed in Fig. 11. The thrust of the spring 166 is accordingly at all times properly aimed with respect to the position of the belt.

In order to guide the vertical motion of the motor and grinding unit, the platform 132 is provided with two or more bosses 182, 184 (Fig. 12) which move in suitable guideways in the cell walls.

The grinding wheel shafts are of various lengths in order that the location of the motor in its cell may be the same for every motor, while the individual grinding wheels are mounted over portions of the work that are at different distances from the sides of the work. The shaft is extended in. the direction toward the center line of the machine the amount needed to position the grinding wheel to grind a longitudinal stripe in the desired position transversely of the work. The typical grinding wheel 81 has a short shaft because it is positioned, as shown in Figs. 10 and 12 to grind a stripe along the outer edge of the work. Another grinding wheel 31, see Fig. 12, has a longer shaft so that it may grind a strip inwardiy of the stripe ground by wheel 31). The shaft lengths for the other grinding wheels are selected in similar manner. in Figs. 10 and 12 the reference characters 1 through 7 have been used to indicate the relative positions of the wheels, and to illustrate the overlapping thereof, which cover one-half of the surface of the work. Later in the specification the numerals 3 through 14 will be used for the seven wheels which cover the other half of the work.

The operation of the side guides is shown by reference to Figs. 4, 5 and 6. Referring first to Fig. 5, the side guides 5'6, 58 are shown with bearing rollers such as 132, 18%, embedded in the faces against which the edges of the slab or work-piece 94 may bear. The side guide hydraulic cylinder 65 of Figs. 1 and 5 cooperates with a similar cylinder 186 to impart sidewise motion to the side guide 58 when required to adjust the machine to the width of the work to be ground. Other

side guide cylinders

188, 1% cooperate to move the side guide 56. A tie-in shaft 1% shown in Figs. 5 and 6 acts in conjunction with a rack and pinion arrangement to insure motion of the side guide 56 parallel to the length of the side guide. A similar tie-in shaft 124 shown in Pig. 5 acts to ensure parallel, motion of the side guide 58.

Referring now to Fig. 6, the cylinder 1% is shown anchored at the right to a bracket 1%, which is in turn either attached to the frame of the machine or mounted upon a separate footing. The cylinder 1% has associated with it a piston rod 1% which is coupled to a supporting member 2150 to the top of which is fastened the side guide 56 and to the bottom of which is attached a rack 2%2. The rack meshes with a pinion 23d rigidly attached to the shaft 192 near the right-hand end of the shaft as viewed in Figs. 4 and 5.

Fig. 7 is a vertical sectional view taken along the line 7 -7 of" Fig; 6; showing the relationship between rack to the shouldered member 212 rides in a tubular extension of the fork-like member 214.

Fig. 9 shows a typical resilient guide mechanism for a hold-down or pressure roll such as the pressure roll 92. The figure shows the hydraulic cylinder 114 rigidly mounted above the pressure roll 92, with hydraulic connections 218 and 22% respectively above and below the piston. The piston rod 222 has a shouldered member 224 attached to its lower end as shown. A relief spring 226 is confined between the member 224 and a mounting member 228 to which latter the roll 92 is rotatably fastened. The member 228 is slidably mounted in a guide 230 supported on bracket 231 by a beam 233 forming a part of the structure 62. A tie rod 232 attached to the shouldered member 224 rides in a tubular extension of the mounting member 228. The roll 92 is shown pressing upon the work 94.

Fig. 14 shows in schematic form a typical hydraulic system for raising and lowering one of the grinding units as a whole to adjust the machine to the thickness of a slab to be ground, and for raising and lowering a grinding wheel relative to the grinding unit of which it forms a part. The latter part of the system includes provision for applying a yielding constant pressure to the grinding wheel when it is in operative engagement with the work. A high pressure pump 234 is provided for raising and lowering all of the grinding units individually or in groups as desired and it will be understood that the purnp 234 is connected to all of the units in the same manner as illustrated in Fig. 14. A low pressure pump 236 is provided for applying yielding constant pressure upon the grinding wheels. In the illustrated embodiment of the invention there are two low pressure pumps each of which is connected with onehalf of the total number of wheels. The low pressure pumps are used only to press the wheels downwardly and the high pressure pump 23:1 is utilized for raising the wheels when desired.

A solenoid-operated self-centering valve 238 is provided for controlling the typical unit cylinder 126. The valve has two

solenoids

240, 242, for lowering and raising respectively. When the lowering solenoid 240 is actuated, fluid from pump 234 is forced through valve 238 and tube 246 into cylinder 126 above piston 244 and fluid is discharged from below piston 244 through tube 248, an adjustable check-valve 239, which resists the flow to a predetermined degree, and valve 238 to the fluid return channel or sump 259. When the raising solenoid 242 is actuated, fluid from pump 234 is forced through valve 238, tube 248 and freely through pressure check valve 239 into cylinder 126 below piston 244 and fluid is discharged from above piston 244 through tube 246 and valve 238 to fluid return 25% Thus, as long as solenoid 240 remains actuated the piston 2 54 is forced downward, lowering the grinding unit as a whole. The adjustable check-valve 239 is so adjusted as to counteract the weight of the grinding unit whereby upward and downward movements occur at approximately the same speed. When solenoid 248 is deactivated, the self-centering valve 238 closes both

tubes

246 and 248 thereby causing the grinding unit to remain fixedly atthe desired elevation. When: solenoid 242 is main-.

tained in the activated state, the piston 244 is forced upward, raising the grinding unit as a whole and the self-centering valve 238 will hold it in place when the solenoid 242 is deactivated. It will be understood that an identical system is provided for each of the grinding units and that the solenoids may be controlled by suitably arranged switches to be described below.

To raise any of the grinding wheels relative to the unit of which it forms a part, to put it in inoperative position for example, fluid from the high pressure pump 234 is admitted through valve 252 into the portion of the typical cylinder 154 below the piston 254. The valve 252 is biased toward a position wherein fluid is permitted to flow from the cylinder through line 253 and valve 252 into the sump 25 Thus, to raise the wheel the solenoid 256 is actuated and upon deactivation thereof the wheel will be free for downward movement. It will be recognized that the piston 254 can be moved upwardly as just described only when fluid above the piston can flow outwardly and suitable provision for such operation is made in the system now to be de scribed.

The low pressure pump 236 is defined in that manner because it operates at a pressure much lower than the pressure at which the pump 234 operates. For example, in an installation embodying this invention the pump 234 operates at a pressure of approximately one thousand pounds per square inch while the pump or pumps 236 operate at approximately two hundred pounds per square inch. In this particular installation each of the grinding wheel driving motors is a seventyfive horsepower motor and each grinding wheel, when new, is twenty inches in diameter and has a face four inches wide. The weight of each grinding unit is therefore considerable and the hydraulic pressures discussed above have been selected as appropriate. Thus the low pressure pump 236 operates at the pressure which is best calculated to produce rapid and efficient grinding of a layer of approximately one-tenth inch in thickness from an ingot or slab of stainless steel when wheels and motors of the selected sizes are used. Such pumps are customarily equipped with pressure regulator valves (not shown) which may be adjusted for optimum results. When the proper pressure has been determined it will be applied to all of the grinding wheels in use at a particular time whereby a smooth uniform surface is assured and the precise thickness desired may be removed.

The low pressure pump 236 is connected to the typical cylinder 154 through a line 257, a valve 258 and line 259 which opens into the portion of the cylinder 154 disposed above the piston 254. The valve 258 is actuated by two solenoids 26d and 262 which move the valve slide in opposite directions when energized. The valve 258 is of the type which remains in the position to which it has been moved after deenergization of the solenoid which caused such movement. The solenoid 262 moves the valve 258 to a position wherein fluid drains from the upper portion of cylinder 154 through line 2559, valve 258 and to the sump 256'. Therefore the solenoid 262 is interlocked with the high pressure valve 252 whereby when the latter is actuated to lift the piston 254 the valve 258 is moved by solenoid 262 to permit the fluid above the piston to return to the sump 250.

The solenoid 260 moves the low pressure valve 258 to a position wherein the fluid from low pressure pump 236 is conducted to cylinder 154 to press the piston 254 downwardly with the pressure selected for optimum operation of the grinding wheel. Such pressure is constant but yielding inasmuch as the piston 254 may be forced upwardly in opposition to such constant pressure whereupon fluid .will be displaced backwardly through the pump 236 to the sump 250. It will be recalled that the high pressure valve 252 is so biased as t'o permit the fluid to drain from the lower part of the cylinder 154 at all times except when the high pressure fluid is used to raise the piston 254. Thus during operation of the grinding wheel in each unit it is pressed downwardly by the low pressure system without resistance from the fluid below the piston. In this manner the grinding wheels may be progressively engaged by the leading edge of the work and individually will ride up over the edge to immediately and automatically come into operation.

Fig. 15 shows in schematic form a hydraulic system for controlling and adjusting the side guides 56, movable pinch rolls 84 and 86 and pressure rolls 88, 90 and 92. A high pressure pump 264, similar to the pump 234, is connected to a plurality of

solenoid valves

266, 272, 278, which are shown as controlling the side guides, pinch rolls, and pressure rolls, respectively. The valve 266 may be of the self-centering type and has two associated solenoids, of which solenoid 263 controls the application of fluid pressure to

hydraulic cylinders

60, 186, 188, 190, in each instance to the end of the cylinder opposite the end containing the piston rod, for the purpose of moving the side guides farther apart. Solenoid 270 con trols the application of the fluid pressure in each instance to the end of the cylinder containing the piston rod, for the purpose of moving the side guides closer together. Detailed operation of the valve action in moving the side guides and in holding them in any desired position is similar to that described in connection with moving and holding the grinding units in the system of Fig. 14. In a similar manner solenoid 274 controls valve 272 to lower a typical upper pinch roll 84 or 86 or to increase the pressure between the pinch rolls and to hold the upper roll in lowered position, While solenoid 276 is provided for raising the pinch rolls or decreasing the pressure between the pinch rolls and holding the upper roll in raised position. Valve 273 is controlled by

solenoids

280 and 282 respectively, to control the lowering and raising of a

typical pressure roll

88, 90 or 92, and for holding such roll in lowered or raised position.

Fig. 16 shows a preferred arrangement of indicators and controls on the console of the operators pulpit 64. The specific choice and arrangement of components is illustrative only and may be varied as desired. The figure shows provision for four pumps in the hydraulic system these being the two high pressure pumps 234 and 264 and the two low pressure pumps 236. Each pump is provided with a pressure gauge 284, a start button 286, and a stop button 288, together with a red light 290 to indicate a running pump and a green light 292 to indicate a stopped pump. A control bank 294, comprising individual start and stop buttons with associated lights, is provided for the grindstone driving motors on one side of the machine, designated A side in the figure. It will be observed, by comparing Figs. 16 and 3, that the buttons are numbered to correspond with the numbers 1 through 7 applied to the units and that they are so arranged as to correspond with the stripes ground by the wheels. This enables the operator to orient the operation of the start and stop buttons with the work being done. The control bank 294 is equipped with indicator lights and operates in similar manner to the con trol bank shown for the pumps. Another similar control bank 296 is provided for the motors on the other or B side of the machine and thus provides an oriented control for starting or stopping the motors in the units numbered 8 through 14. Feeding speed of the work may be varied by the operator by means of a hand wheel 298 which controls the speed of the large direct current motor 38 which drives the table rolls and related parts. The feeding speed is indicated by a tachometer 350. To stop the entire machine in an emergency, a stop button 302 is provided. Up and down controlling buttons are providecl for the pinch rolls and pressure rolls and in and out controlling buttons are provided for the side guides. One pair of pinch rolls is designated as the north pair with up button 304 and down button 306 while the other pair of pinch rolls, designated as the south pair, is provided with up button 308 and down button 310. To control the hold-down or pressure rolls, a control bank 312 is provided with individual up button and down button for each roll. Another control bank 314 provides an in button and an out button for each side guide 58 or 56, which guides are designated east and west, respectively.

Banks

316, 318 of controls comprise up and down control buttons for the individual grinding units on sides A and B respectively and these buttons are oriented with the stripes ground by the units.

Banks

320, 322 of controls similarly comprise up buttons and down buttons for swinging the individual grinding wheels relatively to their respective units so that they may be pressed with predetermined pressure into grinding engagement with the work or lifted out of contact with the work if so desired. The buttons in

banks

316, 318, 320, 322 constitute switches which are connected with solenoids to control valves in hydraulic systems such as are shown in Fig. 14. A bank of red lights 324 may be provided if desired to indicate which of the grindstones are under grinding pressure. A controller 326 is provided for starting, stopping and reversing the direct current motor 38 which drives the table rolls, the controller having a hand wheel 328 for this purpose. A red light 330 is provided to show when direct current is being applied to the motor 33.

As shown in Fig. 2, the operators pulpit 64 is disposed above the worlosupporting table at the inlet end of the machine. The orientation of various controls on the console, just described, is such that the operator can readily make such adjustments or take such steps as may be indicated by his visual inspection of the ground stripes on the work. It may be preferred to locate the pulpit elsewhere with respect to the machine for improved observation of the work in progress. For example, in an installation of this invention, the pulpit has been located along the side of the machine opposite the table-roll driving motor 38 and at such a level that the operators eyes are slightly above the plane of the upper surface of the work. In such position the controls are preferably oriented just as they are in Fig. 16 inasmuch as it requires little experience to translate the orientation through ninety degrees.

The operation of the machine has been set forth in the course of the detailed description thereof. However, such description has been directed primarily to normal operation of the machine in which the slab enters the machine from the right as viewed in Figs. 1 through 4, so that the entire surface may be ground in a single continuous pass through the machine. It should be pointed out, however, that the work may be moved through the machine in either direction with substantially equal facility so that multiple passes may be made simply by reversing the direction of feed of the slab. In either case the grinding wheels will ride up over the leading edge of the work and progressively go into operation as described above. This is a particularly valuable feature inasmuch as a slab, having been passed through the machine from right to left for grinding of the entire upper surface, may be inspected as it lies upon the delivery section 54 (Figs. 1 and 2) and it may be reversed through the machine for spot grinding of those areas which require it. As indicated above, for such spot grinding the wheels that are not needed may be swung upwardly by the wheel pressure cylinders of which 154 is typical. Thus only the required wheels may be lowered in position for operation or, alternatively, the required wheels may be lowered only when spots requiring further grinding have been brought to a position beneath the appropriate wheel.

It will be appreciated that modifications in detail falling within the scope of the present invention will occur to those skilled in the art.

What is claimed is:

1. In a grinding machine for removing a layer of substantially uniform thickness from the surface of an elongated work-piece the combination of a table forsupporting said work-piece with an upper surface thereof disposed in a generally horizontal plane; means for moving said work-piece lengthwise across said table; a plurality of grinding units, each of said units comprising a support, a motor, an arbor rotatable about an axis substantially transverse to the direction of movement of said work-piece across said table, a grinding wheel secured to said arbor for rotation therewith, means for transmitting rotation from said motor to said arbor, and pressure responsive means for moving said arbor and the grinding wheel carried thereby relative to said support in directions parallel with the plane of rotation of said grinding wheel; a frame for supporting said grinding units above said upper surface of said work-piece, each of said units being mounted independently for vertical movement relative to said frame and toward and away from said work-piece; means individual to each of said grinding units for moving each of said grinding units vertically relative to said frame to position each of said grinding wheels in operative relation with said surface of said work-piece; said grinding units being disposed upon said frame in parallel rows extending lengthwise of the path of movement of said work-piece through said machine, each of said grinding wheels being so positioned upon the unit of which it forms a part as to be adapted to grind in a path extending lengthwise of said work-piece and laterally offset from the path of any other of said grinding wheels, andthe adjacent longitudinal edges of adjacent paths being at least coterminous whereby the entire width of said surface of said work-piece may be ground in a single pass of said workpiece through said machine; and means connected with each of said pressure responsive means for supplying fluid under a predetermined yielding pressure to said pressure responsive means whereby any desired number of said grinding wheels may be pressed against said surface of said work-piece with a constant yielding pressure such that each of said grinding wheels so pressed will remove from said surface by abrasion a uniform predetermined thickness of the material thereof.

2. In a grinding machine for removing a layer of substantially uniform thickness from the surface of an elongated work-piece the combination of a table for supporting said work-piece with an upper surface thereof disposed in a generally horizontal plane; means for moving said work-piece lengthwise across said table; a frame for supporting a plurality of grinding units above said surface of said work-piece, each of said units comprising a support, a motor, an arbor rotatable about an axis substantially transverse to the direction of movement of said work-piece across said table, a grinding wheel secured to said arbor for rotation therewith, means for transmitting rotation from said motor to said arbor, and pressure responsive means for urging said arbor downwardly relative to said support whereby to press the periphery of said grinding wheel into engagement with said surface of said work-piece; said grinding units being disposed upon said frame in parallel rows extending lengthwise of the movement of the work through said machine, each of said grinding wheels being so positioned upon the unit of which it forms a part as to be adapted to grind in a path extending lengthwise of said work-piece and laterally offset from the path of any other of said grinding wheels, and the adjacent longitudinal edges of adjacent paths being at least coterminous whereby the entire width of said surface of'said work-piece may be ground in a single pass of said workpiece through said machine; and means connected with each of said pressure responsive means for supplying fluid under predetermined yielding pressure to said pressure responsive means whereby any desired number of said grinding wheels may be pressed against said surface of said work-piece with a constant yielding pressure such that all of said grinding wheels so pressed will remove from said surface by abrasion a uniform predetermined thickness of the material thereof.

3. In a grinding machine for grinding the surface of an elongated work-piece the combination of a table for supporting said work-piece; means for moving said workpiece lengthwise across said table; a plurality of grinding units, each of said units comprising a support, a grinding wheel, means for rotating said grinding wheel about an axis substantially transverse to the direction of movement of said work-piece across said table, and pressure responsive means for moving said grinding wheel relative to said support and toward said work-piece in a direction parallel with the plane of rotation of said grinding wheel; a frame for supporting said grinding units, means for independently moving each of said units relative to said frame to position each of said grinding wheels in operative relation with a surface of said work-piece; said grinding units being disposed upon said frame in parallel rows extending lengthwise of the path of movement of said work-piece through said machine, each of said grinding wheels being so positioned upon the unit of which it forms a part as to be adapted to grind in a path extending lengthwise of said work-piece and laterally offset from the path of any other of said grinding wheels, and the adjacent longitudinal edges of adjacent paths being at least coterminous whereby the entire width of said surface of said work-piece may be ground in a single pass of said work-piece through said machine; and means connected with each of said pressure responsive means for supplying fluid under a predetermined yielding pressure to said pressure responsive means whereby any desired number of said grinding wheels may be pressed against said surface of said work-piece with a constant yielding pressure such that each of said grinding wheels so pressed will remove from said surface by abrasion a uniform predetermined thickness of the material thereof.

4. In a grinding machine for grinding the surface of an elongated work-piece the combination of a table for supporting said work-piece; means for moving said workpiece length-wise across said table; a frame for supporting a plurality of grinding units, each of said units comprising a support, a grinding wheel, means for rotating said grinding wheel about an axis substantially transverse to the direction of movement of said work-piece across said table, and pressure responsive means for moving said grinding wheel relative to said support whereby to press the periphery of said grinding wheel into engagement with a surface of said work-piece; said grinding units being disposed on said frame in parallel rows extending lengthwise of the path of movement of said work-piece through said machine, each of said grinding wheels being so positioned upon the unit of which it forms a part as to be adapted to grind in a path extending lengthwise of said work-piece and laterally offset from the path of any other of said grinding wheels, and the adjacent longitudinal edges of adjacent paths being at least coterminus whereby the entire width of said surface of said work-piece may be ground in a single pass of said work-piece through said machine; and means connected with each of said pressure responsive means for supplying fluid under a predetermined yielding pressure to said pressure responsive means whereby any desired number of said grinding wheels may be pressed against said surface of said work-piece with a constant yielding pressure such that each of said grinding wheels so pressed will remove from said surface by abrasion a uniform predetermined thickness of the material thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,046,801 Kelder Dec. 10, 1912 1,788,249 Philippi Jan. 6, 1931 1,803,752 Ford May 5, 1931 2,453,339 Peterson Nov. 9, 1948 2,617,223 McElroy et al. Nov. 11, 1952