US2174843A - Roller mill having feed controlled grinding rollers - Google Patents

Description

9st. 3, 1939. E. ROTH 2,174 843 ROLLER MILL HAVING FEED CONTROLLED GRINDING ROLLERS Filed Dec. 14, 1937 2 Sheets-Sheet l E. ROTH ROLLER HILL HAVING FEED CONTROLLED GRINDING ROLLERS Filed Dec. 3.4, 1937 2 Sheets-Sheet 2 Patented Oct. 3, 1939 ems ROLLER MILL HAVING FEED CONTROLLED GRINDING ROLLERS Ernst Roth, Uzwil, Switzerland, assignor to the firm Gebruder Buhler, Uzwil, Switzerland Application December 14, 1937, Serial No. 179,782 In Switzerland December 18, 1936 2 Claims.

This invention relates to roller mills having automatic control means for adjusting the grinding rollers, said means comprising a linkage which is controlled by the material fed to the mill and which controls a mechanical driving gearing so that a control lever for adjusting the grinding rollers is adjusted into operative or inoperative position depending on whether the gearing is connected or disconnected.

In a known roller mill of this kind, a linkage operates to either, connect or disconnect a clutch of a gear wheel ratio gearing by influence of which the control lever is adjusted into operative or inoperative position. This driving gearing is very complicated and therefore expensive to manufacture. Furthermore, for effecting the adjusting movements of the control lever, the linkage must counteract relatively large amounts of frictional and spring resistance, so that the reliability of operation of the means for alternately adjusting the lever into operative and inoperative position is considerably reduced, due to the fact that only a small driving effort is exerted on the lever adjusting means by the material fed, particularly, when light material is being ground. For this reason, only a minimum of frictional or other resistances should be opposed to the lever adjusting operation.

In another known roller mill, the grinding rollers are automatically adjusted, by a compression spring which acts on the movable roller bearing being compressed, when the supply of material to the mill is interrupted. This result can be obtained by relatively simple means. However, for compressing the spring, relatively large efforts are required, depending upon the power thereof, as compared with the functioning of the control lever operated arrangements which requires only little effort, since there is no necessity for compressing a spring. On the other hand, the adjustment of rollers by compressing a compression spring is obviously not practicable in roller mills which are devoid of such a spring.

. In contradistinction to these known roller mill arrangements, the roller mill according to the present invention comprises a lever which is reciprocated by the mechanical driving gearing and extends substantially in the direction of movement of a pivot joint provided therein and the rear end of which is adjusted as to height by the linkage, said lever carrying two control members one of which adjusts the control lever into operative position when hitting a stop provided on the control lever, in a raised position of this control member, whereas the other control member releases a pawl securing the control lever in the operative position thereof by engaging with a nose provided on the control lever, in a lowered position of this second control member.

With this arrangement no frictional losses to speak of set up in'the linkage while rockingly adjusting the reciprocating lever about its pivot joint and, as there are no further resistances to be overcome, only a very small effort need be exerted by the material fed for adjusting the reciprocating lever. Furthermore, this driving arrangement is distinguished by great simplicity, apart from its great reliability of operation, on account of the effort for adjusting the reciprocating lever being only small.

In the accompanying drawings an embodiment of the invention is illustrated by way of example only, in which Fig. 1 is a cross section of the roller mill according to the invention showing the control device with the control lever in operative position;

Fig 2 shows an elevation of the control device with the parts thereof in their relative positions immediately before moving the control lever out of inoperative position;

Fig. 3 shows an elevation of the control device similar to that of Fig. 2, but with the parts thereof in their relative positions prior to moving the control lever out of operative position, and

Fig. 4 shows an elevation of the control device with the parts in relative positions as assumed during moving the control lever out of operative position. [In the drawings, the numeral l designates a flap valve for regulating the flow of material fed to the grinding rollers 20, 25 through a feed chute .l'l which is included in the housing l8 of the roller mill.

The flap valve l is mounted on a pivot in the chute El and carries a control arm 2 firmly connected to this valve and is kept under the influence of an adjustable weight 2" on a lever arm 2' extending in prolongation of the arm 2 rearwardly thereof, as shown in the drawings in the upper right hand corner of each figure thereof. The arm 2 thus tends to press the valve against the end position B, as indicated in chaindotted lines in Fig. 1. When the feed is in progress, the flap valve is kept in the open position A by the weight of the material exerted upon the valve, whereas if the feed ceases, the flap valve is closed by the weighted lever 2'. The control arm 2 is pivotally connected to one end of a rod 3. The lower part of, the rod 3 supports one end portionof a two-armed lever 4 pivotally connected to a pin it. The other arm of this lever ends in two control members 5 and B. The pivot pin I0 of the lever 4 is connected to one end of a two-armed lever B oscillating on a 8 is linked by means of a connecting rod to a crank arm 1 fixed on an axle [9 of the grinding roller 20. Irrespective of whether the grinding rollers are in operative or inoperative position, the lever 4 keeps on moving to and fro by action of the crank arm 1. The relative arrangement of the levers 4 and 8 is such that the reciprocating lever 4 extends substantially in the direction of movement of the pivot pin I thereof during the travel of the latter together with the oscillating lever 8.

When by gravitational action of the feed of material the flap valve I is rocked into position A shown in Fig. 2, the member of the lever 4- comes into contact with a cam II on the control lever. l4, thereby raising the. latter into operative position shown in Fig. 1. When the feed of materal ceases,. the flap valve I is rocked into position B.- in Fig. 1 by action of the counterweight 2-, whereby the member 6 of lever 4 comes into contact with a nose l3 on a detent l2, so that this detent is disengaged from a stationary tooth l5 holding the lever [4. in operative position when engaged by said detent. The control lever I4 is thus pulled into the inoperative position shown in Fig. 2 by action of the weight ofthe movable grinding ro11er'25 through the intermediary of a tensioning device 2| including a tension. rod IS.

The tension rod I6. acts upon a mounting arm 22 which is rockable about a. fulcrum 23 and carries the bearing of the axle pin 24 of the grinding roller 25,,so that the spacing of the grinding rollers can be varied within limits corresponding to the positions A and B of the regulator flap valve, by adjusting the lever l4 into operative and inoperative position respectively.

In adjusting the grinding rollers for operation, the lever 14. is. rocked from the inoperative position of the. same, as shown in Fig. 2, into the operative position shown in Fig. 1 by cooperation of the, control member 5 with the cam member ll, when this control member assumes a raised position in response to the regulator flap valve being, forced. open by material falling through the hopper I], in conseqence of which the grinding rollers are. closed on each other. While the levers B and 4 are then conjointly moved to and fro. by action of the crank arm 1, the leverl4 remains securedin operativeposition by interengagement of the. detent l2 with the tooth I5.

These. movements of the automatic control means for adjusting the grinding rollers will be still better understood from Figs. 3 and 4 of the drawings. After. the flap valve I has been rocked from the full line position A into the chain-dotted position B and thus the rear arm of the lever 4 has been raised accordingly, the control member 6, assumes a lowered position, asshown in Figs. 3gand 4, for cooperation with the nose lswhich is provided on, the lever I4 through the intermediary of the detent I 2. By this means, the detent I2. is rocked from the position which it occupies in Figs. 1 and3 into the position shown in, Fig. 4 and, is. thus released from engagement with the tooth I 5. Consequently, the control lever .l4,.is released from locking engagement whereupon this lever moves from operative position into inoperative position, by action of the tensioning' device 2| and the tension rod l6, as previously described. 7

2,174,843 pivot pin 9. The other or lower end of this lever Various changes and modifications may be made in the practice of my invention without departing from the principle or spirit thereof, by adding customary practice and established ..knowledge of the art to the present disclosure and the scope of the appended claims is not to be regarded as limited except as specified therein.

I claim:

1. In a roller mill having automatic control means for adjusting the grinding rollers selectively to operative or non-operative position in dependence on the feed or interruption of the feed of material to the grinding rollers, a pair of cooperative grinding rollers, means for adjusting the gap between said cooperative rollers from operative to non-operative position and vice versa, a lever for controlling said adjusting means, said: control lever having an abutment and also having a latch for holding it in one position, a mechanical driving means driven by the mill for engaging said abutment to move said: leverin one direction, said latch having a releasing arm spaced from saidabutment, said driving means including a continuously reciprocating lever for selective cooperation with said control lever abutment and latch releasing arm in dependence on the feed of material to the rollers, and a linkage controlled by the feed of material to said rollers articulated to said reciprocating leverto prevent the transmission of reactive impulses fromsaidreciprocating lever tosaidlinkagewhile said linkage positively adjustssaid reciprocating lever in accordance withthemovements of said linkage for cooperation witlisaid controllever for moving said control lever into operative and inoperative positionselectively in response to progress or interruption of said feed.

2. In a roller mill, apair of cooperating grinding rollers, automatic control means for adjustingthe relative position of the grinding rollers to-and from operative position in dependence on the feed of material to'be ground, said control means including a-lever for controlling said adjusting means, said lever having an operating abutment and having a latch for holding it in one position, mechanical'meansfor driving said control lever engaging said abutment to move said lever in one direction, said latch having a releasing armspacedfrom said abutment, said control leverdriving means including a pivotal reciprocable lever, means driven by a grinding rollerfor continuously reciprocating said lever, mounting means'for said reciprocating lever arrangedin-said driving means for conjoint movement with said reciprocating lever, said pivotal lever extending substantially in the direction of said conjoint movement, and a linkage controlled by the feed-of material to said mill articulated to thepivotal reciprocating lever towards its outer end to prevent the transmission-of reactive impulses 'fromsaidreciprocating lever to said linkage while said linkage positively adjusts said pivotalreciprocating lever in accordance with the movements-of said linkage for cooperation with saidabutment of said control lever or said latch releasing arm for adjusting said control lever into operative and inoperative position respectivelyin response to progress or interruption of said feed.

' ERNST ROTH.

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