US2690306A - Apparatus for automatically positioning the rolls in roller-mills in accordance with the material feed - Google Patents

Description

Sept. 28, 1954 F. TANNER 2,690,306

APPARATUS FOR AUTOMATICALLY POSITIONING THE ROLLS IN ROLLER-MILLS IN ACCORDANCE WITH THE MATERIAL FEED Filed Dec. 27, 1949 5 Sheets-Sheet l lwmm l ifz 751men 6?? Sept. 28, 1954 F. TANNER APPARATUS FOR AUTOMATICALLY POSITIONING THE ROLLS IN ROLLER-MILLS IN ACCORDANCE WITH THE MATERIAL FEED Filed Dec. 27, 1949 5 Sheets-Sheet 2 3 Sheets-Sheet 3 FRITZ TANNER C. 7. 7 e@ his ATTORNEY Sept. 28, 1954 F. TANNER I APPARATUS FOR AUTOMATICALLY POSITIONING THE ROLLS IN ROLLER-MILLS IN ACCORDANCE WITH THE MATERIAL FEED Filed Dec. 27, 1949 TF8 N 8 1 g UN mm m mm mm! mg P P m? i 2 k a @N mm mm P mm! A I m. G NT P 2 I) M WQ A mm H m N N I\.\|\\ mT W F mm m w m i m \mm M E 8 mm mm, I W C mm m 5 mm Patented Sept. 28, 1954 APPARATUS FOR AUTOMATICALLY POSI- TIONING THE ROLLS IN ROLLER-MILLS IN ACCORDANCE WITH THE MATERIAL FEED Fritz Tanner, St. Gallen, Switzerland, assignor to Gebrudcr Buhler, Uzwil, Switzerland Application December 27, 1949, Serial No. 135,239

Claims priority, application Switzerland April 14, 1949 4 Claims. 1

My present invention relates to a starter and regulator for roller mills comprising pressurefluid servomotors for automatically throwing the grinding rollers and feed rollers in and out of gear, and a device disposed in the goods inlet for controlling the pressure-fluid feed to the servomotors.

The starters and regulators of the type indicated, as known in the art of grinding grain and the like, do not operate quite satisfactorily and do not quite correspond to practical requirements owing to the fact that the grinding rollers are thrown in and out of gear at a comparatively slow speed.

While in the case of a manually operated starter, the latter is quickly thrown in by the miller through a good pull, and the grinding rollers through exerting a blow onto a pawl which looks the engaging lever are quickly released under spring pressure. The automatic throwing in and out of gear is slowed down through the use of a pressure-fluid servomotor.

The said disadvantage of known roller mill starters and regulators of the type indicated and further disadvantages which will become apparent to one skilled in the art from the following description of one known form of starter and regulator, are avoided by virtue of my present invention in that a reversing valve is provided in the pressure-fluid supply pipe of the servomotors, which valve is reversible through the controller in order to permit of quickly throwing the grinding rollers and the feed rollers in and out of gear.

The invention will be described in more detail in connection with the accompanying drawing wherein like characters of reference indicate identical elements, and wherein Figs. 1 and 2 show two different forms of my present invention in vertical section applied to a known roller mill.

Fig. 3 is a diagrammatic view showing a number of units illustrated in more detail in Fig. l, with connecting fluid pressure conduits shown therein; and

Fig. 4 is a diagrammatic view similar to that of Fig. 3, illustrating a number of units of Fig. 2.

Fig. 1 shows a known double roller mill in the casing l of which two pairs of grinding rollers 2, 3 and two pairs of feed rollers 4, 5 are disposed. The regulating mechanism for the movable grinding roller of each roller pair is disposed out side the casing l and laterally thereof. For the sake of clarity, the regulating mechanism associated with the right-hand mill side is shown in the drawing on the left-hand mill side. The said regulating mechanism comprises a swing bearing for the movable grinding roller 2, which bearing is engageable through a rod 1 provided with a handwheel l. The said rod is pivoted to an engaging lever 8 which is mounted on the coupling shaft 9. Numeral l0 designates the disengaging spring acting on the bearing 6. A servomotor piston II is operatively connected to the lever B and operates in a cylinder I2 fixed to casing I. Numeral I3 designates a fixed abutment for lever 8. A hopper I4 for the goods to be ground is disposed above the feeding rollers 4 and 5 and is closable at the bottom through a feeder segment l5 disposed above the feeder roller 4. A lever 16 serves for actuating the segment l5 and is connected to the piston N3 of a second servomotor through a rod H. The piston I8 operates in a cylinder H3 in which is disposed a spring 24 which acts on the piston l8 so that the latter tends to move the segment I5 to closing position. A pump 23 delivers pressure fluid through piping 25 into the cylinders 12 and I9. The fluid arriving in cylinder [9 tends to depress the piston 58 against the action of spring 24 and thus to open the segment l5. Such opening action, however, only takes place when the bore I8 in piston i8 is closed. When the bore I8 is open, the fluid can return through piston [8 to pump 23. A control pin 20 is provided for closing the bore I8 and has a tip 20' at the bottom, which cooperates with the said bore, While the pin at the top is pivoted to an arm 2| on which is disposed a controller 22 for the goods in hopper l4.

In Fig. 1, an auxiliary reversing slide valve is shown, which comprises a cylinder 26, a piston 21, a spring 28, and seven ports 29-35. The said valve for the sake of clarity is shown in a larger scale than the mill unit. The said valve, as regards its stroke and diameter, actually is substantially smaller than the piston l8 associated with feeder segment 15. The piston 21 has a relieved portion forming an annular chamber 36. The fluid delivered through the pump 23 flows through line 25 and a wide bore 33 into cylinder 25 and thence into the annular chamber 36 of piston 21. In the position shown, the fluid is discharged through port Bil and flows into cylinder 52. The latter thus communicates directly through large-diameter lines with the pump or the central circulating system, and the pressure in cylinder i2 is exactly the same as throughout the system. The port connecting the main line 25 with the pressure space of cylinder 26, is or" very narrow bore. A further line 28, of somewhat larger core, connects cylinder 25 with cylinder H5. The automatic regulating system operates in the following manner: When the roller mill is thrown into gear, the pump 23 supplies fluid into main line 25, under a pressure regulated by means of an overflow valve (not shown) provided between lines 25 and 35, from which valve the pressure fluid returns to the suction port of pump 23 through return line 35. The controller and consequently the tip it of control pin 25 are retained in their upper position by the action of spring The upper end of bore 53' of piston i3 is fully open and the pressure fluid supplied from the main-line 25 to the branch line through the very narrow port 3 freely escapes through bore 58. Thus the pressure in the branch line remains low. The spring maintains piston l 8 in its upper position and holds the segmental feed-gate in closing position. Piston 2'? is held spring 23 in its lower terminal position. Port lid of cylinder 25 is closed and port 3i opened, the main line 25 leading to the servomotor cylinder l2 thus being connected to the return line The piston ll of servomotor i2 is retained by action of spring Ill in its left terminal position and thus the grinding rollers 2, 3 are out or grinding en agement. As soon as goods are supplied to the rol1er'nill, the pin 28 is depressed by the goods running into hopper I l and weighting the controller 22, whereby the bore i8 is closed by the tip 28'. The pressure fluid then depresses the piston 58 until a passage of such size is created between the tip it of pin 2!? and the upper end of bore it that the fluid can escape through said bore. The pin 26 and piston 28 thus always are moved as if they were rigidly interconnected. The fluid pressure is defined by the strength or" spring 2%, the diameter of piston 58 and the position of tip 26, which latter depends on the quantity of goods supplied to the roller mill. Substantially at the same time at which the segmental feed gate I is opened, the piston 2? of the reversing slide valve 26 is pushed to its upper terminal position by the rising pressure below it, thus opening the pressure fluid main line 25 to the servomotor 52. The latter then suddenly moves the grinding roller 2 into grinding engagement with the roller 3, the servomotor 22 being connected through large-diameter lines with the pump 23.

The opening of the segmental feed gate i5 is continuously changed dependent upon the quantity of goods supplied to the roller mill, while the grinding rollers remain in engagement with each other. As supply of goods through the hopper Id ceases he controller 22 permits the spring 22' to raise the controller, the lever 2i and the pin 26. The latter uncovers the upper end of bore l8 in piston i3, and like pressures are built up below piston 2i and above piston H8. The magnitude of this pressure here again is defined through the d iameter of piston 53 and the spring 24 The said elements are so designed that the pressure sufiices to compress the spring 28 of piston Ti and maintain the latter in the position shown. When, however, the pin 25 uncovers a part of bore is in. piston is, the fluid is discharged through said bore at a quicker rate than at which it can be replenished through the narrow port The space under piston 2i thus is depressurise spring 28 can depress piston 22 to its lower position. Communication between the ports and 33 thus is interrupted, and communication established between port 31 and discharge port The fluid thus may flow from cylinder 52 through large-bore lines to pump 23, and stopping is effected very quickly. The piston whi n has a very small stroke only, never can st 1" still in an intermediate position, but always will occupy either of the terminal positions at once so that the ports 33 and 3| in cylinder i1? always fully open.

In Figures 1 and 2, the piston valves 2? are provided with a stop ll to form an annular channel around the same when the piston valve 23: is in its down position. In this lowermost position of the piston valve 2! pressure fluid can flow to the underside of the piston valve 21 from the restricted or smaller conduit 34 into the space low the piston slide valve 2'1, and building up pressure moves the piston valve 21' against the action of the spring 28, to its uppermost position, provided fluid is prevented by the valve from ii-owing through the channel 8%.

Owing to the very narrow bore in port. 35-, the piston 93 of feeder segment l5 moves at a slower speed than when controlled only by the pin Such slower speed, however, is not a disadvantage, but an advantage, since the goods, e. g. the l -t husk oi the third and fourth groats, does not flow uniformly through the hopper i l past the controller but tends to stick or form bridges and then to give way suddenly. The piston is of the arrangement shown in Fig. 1 follows up such irregularity only slowly and equalizes the same so as to bias the position of feeder segment inconsiderably and so as to maintain uniform feed of the goods.

A further feature of the form of invention shown in Fig. l is that only a very small tion of the total pump delivery flows throu h narrow port E l so that t -e fluid cons for the slow movements of piston 13 with feeder segment i5 is small, since piston l l for the ing rollers does not consume any pressure fluid when engaged.

Finally, the pressure in the cylinders i9 and by suitably selecting the diameter of piston and the spring may be maintained at a lower value than in the pump piping 25 or in the central supply system, and the feeder segments i5 of all the mill units hooked up thus can operate independently of each other.

In Fig. 3, the respective reference characters are the same as in Figures 1 and 2 for the corresponding parts, except that a further line :Jd from the cylinders is to the pump is shown This conduit 39 is merely an elongation of e conduit adjacent the cylinder IS in l, or an elongation of the conduit from the check valve 38 to the pump 23, in Figure 2.

In Figures 1 and 2, an overflow valve shown for taking care of any overflow pressurthe usual spring therein being correspondi regulated.

While Fig. 3 diagrammatically shows a number of units illustrated in Fig. 1, the Fig. 4i is similar diagrammatic illustration of a series of units shown in Fig. 2.

In the second form of my present invention shown in Fig. 2, the feeder segment I5 is not regulated through a servomotor l8, 19 but is moved through a conventional feeling flap Ma in hopper i l by means of levers l6 and Ida. A slight movement of said flap in its topmost position, i. e. when goods run no more, may be utilized for quickly starting and stopping the grinding and feeding rollers by means of the control slide valve. For such purpose the line 29 of the latter terminates in a small check valve 38 which in operation is closed through the pressure in line 29. When goods run no longer, i. e. when flap Ma; is at the highest elevation, the valve 38 opens and the fluid can quickly flow from line 29 back to the pump, since fluid cannot flow so quickly through the very narrow port 34. The piston 21 thus is lowered and uncovers the large-bore port 3| through which the fluid then flows from the cylinder i2 into the return line 35. Piston H thus disengages quickly. When goods run again, the operation described is reversed.

By adding, in the form shown in Fig. 1, a stop valve 2lla in the line 2e connecting reversing valve E6, 2'? and regulator I820, the supply of fluid to the latter may be interrupted. When said valve 23a is closed, the pressurized fluid, e. g. compressed air, supplied through fine-bore port 34 pushes the piston 21 of the reversing slide valve upwardly, and the grinding and feeding rollers thus remain in gear, even though there is only a small quantity of goods left in hopper I d, i. e. when the regulator I32fi would throw the rollers out of gear. It is, however, desirable in such case to let the rollers remain in gear in order that the hopper l4 may be completely emptied through the narrow gap between segment l5 and roller l, which gap is always present.

When compressed air is used as fluid, all the return lines to the pump are eliminated. Figs. 1 and 2 for such case show the piping system for the reversing slide valve in dash-and-dot lines. When, further, connecting a narrow pressure line at 32, fresh compressed air also flows into the discharge line 35 when the reversing slide valve is disengaged, i. e. when piston 21 is fully depressed. In such latter case, not only the spent air from cylinder i2, which will flow through port El, but also fresh air flowing through port 32 will be available for actuating a signal device 31. The latter will be heard as long as the piston remains in its bottommost position, i. e. as long as the mill unit is inoperative. As soon as the unit is put in operation, the signal pipe 31 is silenced.

The rod ll of piston l8 of the servomotor also may actuate the speed governing means (not shown) of the grinding and feeding rollers, besides the feeder segment I5.

When the controller 22 only performs the operation of throwing the grinding rollers and the feeding rollers in and out of gear, while the supply of goods (by means of segment 15) is regulated manually or mechanically, the piston [8 of the arrangement shown in Fig. 1 may be blocked in cylinder til, the mode of operation of the reversing organs remaining the same.

in the two forms of invention described with reference to Figs. 1 and 2, a uniform and high pressure is maintained in the servomotors for starting and stopping the grinding and feeding, and in the supply pipes for the servomotors. In the servomotors for regulating the supply of goods, and in the pressure spaces of the reversing slide valve a lower pressure prevails. In the case of a central fluid supply to a plurality of parallel-operating mill units, the said lower pressure may be difierent for the various units in order to attain a proper operation of the units when they encounter different resistances.

What I claim as new, and desire to secure by Letters Patent, is:

1. A system for regulating the grinding gap of a roll pair dependent upon the quantity of material fed thereto, having a pair of grinding rollers, adapted to be put into and out of grinding relation, a servomotor having a cylinder and a piston, means connecting said piston with at least one of said rollers, a spring interposed in said means, the tension of said spring being related to the diameter of said piston, a hopper having a wall, a material flow controller in said hopper, a pair of feed rollers in the said hopper, and in the path of said material flow from said hopper wall, and spaced from said wall one roller above the other, a feeder segment disposed between said hopper wall and said upper feed-roller, means connecting said feeder segment with said mate rial controller, said means including fluid pressure operated means having a cylinder and a valve and a valve stem, said valve stem being movable by said fluid pressure and connected with said controller, a pump for said pressure fluid, and a conduit from. said pump to said grinding roller operating servomotor for placing the grinding rollers into grinding position, and for supplying the said valve cylinder with pressure fluid to operate said feeder segment to open the material flow to the feeder rolls, and thus to said grinding rollers, the combination of a slide valve mechanism interposed in said pump conduit leading from said pump to the grinding roller servomotor, said mechanism comprising a cylinder with conduit openings, a piston slide valve in said cylinder having a hollow interior and an outer cir cumferential groove, a spring in said valve interior having one end acting against said slide valve, and the other end against said cylinder, said slide valve being shorter than the interior length of said cylinder, the aforesaid pump conduit supplying fluid to said outer circumferential groove of said slide valve, when said valve is in one position, a conduit connecting with the space in said circumferential groove and with the conduit to said servomotor cylinder, and a restricted conduit supplying fluid to said slide valve cylinder outside of said piston slide valve, a conduit guiding said restricted fluid from said slide valve cylinder to the feeder segment cylinder of the aforesaid fluid pressure operated means, a conduit leading off from the pump conduit for supplying the slide valve cylinder with fluid when the slide valve is down, a conduit leading off from the servomotor conduit and to the upper part of the slide valve cylinder when said slide valve is down, and a conduit communicating with the interior of the slide valve cylinder and with the pump for returning the fluid returning from said servomotor to said pump, whereby the fluid from the pump unrestrictedly passes through the groove in the slide valve to the servomotor to actuate the piston in the servomotor cylinder to place the grinding rollers in grinding relation, to obtain a fast grinding engagement, and the fluid return from said servomotor to the pump flows promptly through unrestricted conduits, enabling the spring at the servomotor to place the grinding roller to ungrinding relationship, the feed segment opening and closing its space in response to the amount of flow of the material, the restricted fluid flow below the said slide valve actuating said feeder segment means to open and close said i'eeder segment in respect to said feeder rollers.

2. The structure of claim 1, in which the said fluid pressure operated means is a servomotor in which the piston has a channel from top to bottom of said piston and the valve stem is adapted to open or close said channel depending on the position of said material controller.

3. The structure of claim 1, in Which the said fluid pressure operated means has its valve stem resting on a material controller in the form of a hinged plate, and a lever interposed between said plate and the said feeder segment.

4. The structure of claim 1, in which a plurality of such structures are adjacent each other 15 having common conduits to and from said pump.

References Cited in the file of this patent Number Number UNITED STATES PATENTS Name Date Moog Sept. 9, 1930 FOREIGN PATENTS Country Date Italy June 18, 1938 Great Britain July 28, 1932 Germany Dec. 11, 1930 Germany Mar. 10, 1939

Images