US1519991A - Pulverizing mill - Google Patents

Description

Dec. 16, 1924.

C; H. BREERWOOD PULVERIZING MILL Filed March 7, 1924 INVE TO XMATTORNEYfl Patented Dec. 16, 1924.

FFHQEQ PATENT CHARLES H. BBEERWOOD, OF ALLENTOWN, PENNSYLVANIA, ASSIGNQR TO FULLER- LEI-IIGH COMPANY, A CORPORATION OF PENNSYLVANIA.

PULVERIZING MILL.

Application filed March 7, 1924.

To all whom it may concern:

Be it known that I, CHARLES H. Bnnnnwoon, a citizen of the United States, residing at Allentown, in. the county of Lehigh, State of Pennsylvania, have invented certain new and useful Improvements in Pulverizing Mills; and I do hereby declare the following to he a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to pulverizing mills of the type set forth in U. S. Letters Patent Nos. 8%),779; 922,468; 1,039,721, and 1,358,837, issued to James W. Fuller and known as the Fuller mill. This type of mill embodies in its construction a grinding or pulverizing ring in which the material is reduced to a finely divided state by means of appropriate grinding devices, usually a plurality of balls. The grinding ring forms a raceway for the grinding balls and the latter are propelled about the raceway by pushers mounted on a yoke, in turn connected to a power driven shaft. This general construction is illustrated, for example, in U. S. Letters Patent No. 1,358,837. particular type of mill two grinding balls are employed with corresponding pushers to propel them, these pushers being mounted on a pair of yoke arms. Two other yoke arms carry a pair of plows which are arranged symmetrically with the grinding balls about the yoke and are adjusted to operate in the grinding ring. Each plow has a forwardly projecting, downwardly extending inclined surface so that the material passed over by the balls is pickedup by the plow and elevated to the region above the grinding ring where there are lifting devices, such as a set of lifting blades, supplemented by a superimposed fan for carrying the pulverized material to the upper part of the mill where it is floated against a screen for the separation of the fine from the coarser particles, or, as in another type of mill, carried into air currents for ultimate separation by an air separator. In the mill just described there are usually employed two grinding balls with their pushers and two plows which lie between the grinding balls.

It has been found that the plows as illuss t din Lett rs Patent No, 1,358,837 ar In this Serial No. 697,544.

ineffective in practice for preventing the accumulation of material which banks or packs around the grinding ring out of the range of action of the grinding balls, and also out of the path of the plows. This material consequently is not reduced to pulverized form and since the plows arc ineffective to elevate it to the upper Zones of the mill where the coarse, unground particles would again find their way back to the grinding ring for pulverization, the result is that a considerable amount of power is required to drive the grinding balls and plows against the resistance of the packed material and the output of the mill is re duced. Furthermore, with the type of mill above illustrated, there is used one plow for each ball. with its pusher and in the mill shown in the patent the yoke has four arms, two of which serve to carry the pushers, the other two supporting the plows. l fhile yokes of a greater number of arms may be used, mechanical considerations and also the limitations in the available space within the grinding ring have made a yoke having four arms the most satisfactory construction, although in such a mill but two grinding balls are used.

The object of this invention is to provide a mill of the type described which is of increased efficiency and output by reason of the fact that a greater number of balls may be employed for a given s ze of mill. and these balls are propelled by devices which prevent the accumulation of unground, partially ground, or fine packed material within the grinding ring. The means by which the propelling and lifting function is performed may be termed. plow pushers, and as will later be pointed out these devices afford various other advantages in mill. construction which will be apparent from the more detailed description now to follow.

This invention, therefore relates to an improvement in the grinding structure and involves the provision of devices which perform the combined functions of the plows and pushers heretofore employed. These devices operate in the grinding ring and are carried by the yoke arms so that with the same four-arm yoke ordinarily used, it is now possible to drive four balls and also to provide the usual plows. Each device or p o p h r a "curved. face d pt d to engage a ball, and extending transversely across the bottom of the device is a fin or rail which serves to dislodge the material packed down in the raceway by the ball. On the outer face of the plow pusher is another fin or rail which extends upwardly to the rear edge of this face and so projects a slight distance into the grinding ring. The transverse fin curves rearwardly at its outer end and merges w th the second fin so that the two may be considered continuous. The fins cooperate with the grinding surface to free the packed down material and to elevate it so that the lighter particles enter the Zone of action of the lifting blades while the coarser particles fall in front of the next succeeding ball.

In the accompanying drawings there is illustrated that embodiment of the invention which is now preferred. and

Fig. 1 is a sectional view in elevation of a Fuller mill of the type illustrated in U. S. Letters Patent No. 1,358,837. in which there is employed a yoke of the type illustrated and described in my co-pending application Ser. No. 697,545, filed March 7. 1924. this view being on the line 1.--l of Fig. 3.

Fig. 2 is an enlarged view in elevation of the yoke shown in place in Fig. 1. and showing the balls and the plow pushers. lifting devices and fan all mounted on the yoke, in superimposed relation.

Fig. 3 is a plan view of the arran5,;'en1ent illustrated in Fig. 2, certain of the plow pushers having been omitted Fig. 4: is an enlarged plan improved plow pusher.

Fig. 5 is a side elevation.

6 is an end elevation showing the surface which engages the ball. and

Fig. 7 is a. detail View in section showing a portion of a Fuller mill in which there is used the yoke illustrated in U. S. Letters Patent No. 1 3558.837.

The details of the construction of the mill illustrated in Fig. 1 and its operation are fully set forth in U. S. Letters Patent No. 1,358,837, and need not here be described in detail. The mill as shown in F i g. 1. has an outer sectional casing 3 in which the material to be pulverized is introduced through the feeder Q. Mounted in appropriate bearings and extending through the mill is a vertical. shaft 10 which carries a yoke 1.1 and which is driven by a pulley 12 connected, for instance by means of a belt. with any suitable source of power. not shown. At approximately the u'iid-point of the mill is a grinding ring 13 and mounted on the shaft 10 is a carrier 14.

The yoke 11 which forms the subject matter of my co-pending application, previously referred to. is seen to consist of a central hub 15 from which extend radial arms 16 forming a spider, the outer ends of which view of the are joined by a ring 17. Extending downwardly from this ring 17 are arms 18 whicl project into the grinding zone.

19 which travel around the raceway provided by the carrier and the ring are illustrated as being four in number and accordingly there are four of the downwardly extending arms 18 and on the lower ends of these arms are mounted the plow pushers 20. Each plow pusher is formed with a central hub 21 extending slightly above its upper surface 22, the edges of the hub eing beveled away as at 23 so as to permit the material entering the mill to slide off the upper surface into the grinding Zone. llach hub has a square socket 25 into which enters a square shank at the lower end of each arm 18 and the body of the plow pusher has a transverse bore 25 so that a locking pin may be inserted through the plow pusher and through a suitable aperture in the square shank to hold the plow pusher in position. Extending forwardly from the body of the plow pusher is a projection 26 which is slightly curved on its front surface so as to provide a seat for the ball. As shown in Fig. 1 the lower face 27 of the extension 26' lies at some distance above the surface of the raceway and extending across the lower surface of the body of the plow pusher is a fin or rail 28 which curves inwardly near the outer edge as at 29 where it joins a lateral fin 30 extending to the rear of the outer face of the body of the plow pusher. The two fins merge into one another so as to form a smooth surface and the fin 30, as will be apparent from Fig. 1 extends into the roi1- cave portion of the grinding ring 13. the yoke with the plow pushers rotates the fin 2S dislodges the material which is likely to be packed in the raceway and the loose material is thrown outwardly, passing under the rounded leading edge 26 of the extension 26. The material then passes over the fin 30 and is lifted by reason of the inclination given that fin. As the yoke is rapidly rotating the material so dislodged is accordingly elevated so that part of it enters the zone of action of the lifting blades 31 carried by the yoke and the coarser particles which are not raised sufficiently to be brought under the influence of these blades are deposited in the path of travel. of the next succeeding ball in the series. The blades 31 are in the form of fins which ma be bolted to or formed as an inte ral part of the arms 18 and ring 17, and each of these arms has such a blade which has an upward and rearward inclination. Also placed above these blades are fans 32 which are carried by brackets 33 extending upwardly from the upper surface of the spider 16. These fans serve to float the material against the screen 34 in the upper part of the mill and the particles which are of a size The balls l (ii i sufficient to pass through'the screen then descend in the space between the screen and the casin finally entering the space 36. whence they are removed through a spout. 37.

To aid in removing the material from the chamber 36 there is provided the platform 38 mounted on the shaft 10.

The mill in which the plow pusher is made use of has been described as having the new yoke which forms the subject matter of my co-pending application previously referred to. That yoke has vertically extending arms and the plow pushers accordingly have vertical sockets into which the shanks on the ends of these arms enter. It is possible, however, to make use of the new plow pusher with the yoke illustrated in Patent. No. 1,358,837, which has radial arms lying. in a horizontal. plane. For this purpose it is only necessary to rearrange the location of the socket 24 and the bore 25. The type of plow pusher which may be employed with the old form of yoke is shown in Fig. 7 and it will be seen that this plow pusher has a horizontal socket 39 corresponding to the socket 24 and a vertical locking pin aperture 40 corresponding to the bore 25. In other respects the construction of the plow pusher is the same.

The operation of the mill provided with plow pushers is in all respects similar to that of the mill having individual plows and pushers but on account of the greater number of balls which may be employed and of the prevention ofthe packing of the material in the raceway the efiiciency of the grinding operation is greatly increased and power losses are eliminated, while the out put of the mill is increased. As is the case in the mill illustrated in the patent referred to. the material to be ground is fed by means of the feeder 9 and passes downwardly into the mill. The screen 34: is of a mesh such as to permit the passage therethrough of particles of the intended size and'if there are particles ofthe material fed of a sufficient degree of fineness to pass through the screen these particles will be driven out by the blades of the fan 32. They will be aught by the outer wall of the casing and will fall down through the passage 35 into the chamber 36, from whiehthey will be discl'iarged through the spout 37, their removal being assisted by the rotating platform 38. Should such fine particles fall beneath the fan blades they will be driven upwardly by the lifting blades 31. The particles that are too large to pass. through the screen will fall into the pulverizingzone where they will be ground between the grinding ring and the balls. As the material .is passed over by the balls it will be packed down against the grinding ring but the plow pusher propelling each ball will dislodge the nateria] and-cause it to be lifted and conveyed to the rear. The lift.- ing action of that portion 30 of the lm on the outer surface of the plow pusher will causethe material to be raised sufficiently so that the lighter particles will come into the zone of action of the lifting blades 31, whence they will be elevated sufficiently to be acted upon by the fan blades It will be noted that the outer and lower edge of. the curved portion of the transverse fin is given a curve such that it may cooperate with the surface of. the grinding ring, thus insuring a satisfactory lifting action. The particles which are too large and heavy to be raised by the fin on the plow pusher into the zone of action of the lifting blades 3] will be discharged in the path of travel of the next succeeding hall and consequently the mill equipped with the plow pushers will operate to the best advantage because the material will be constantly forced in front of. the balls and placed in such posi tion that the balls are able to carry on the most efficient grinding operation.

B the provision of the propelling devices provided with lifting means itwill be seen. that the mill may be used with a larger number ofhalls than was heretofore possible and each ball will. perform its function more satisfactorily since the material to be ground is always placed directly in front of the ball and not allowed to become packed in, the grinding zone out of range of the balls. The capacity of. the mill is, therefore, materially increased not. only on account of the additional grinding means that may he used but also on account of the. greater elliciency of these grinding devices. Furthern'iore. since raking is prevented the expenditure of power necessary to operate the mill is considerably reduced and the material may be more quickly placed in the desired condition of fineness.

I claim:

1. In a pulverizing mill, a pnlverizing zone containing a raceway, a plurality of revolvably mounted arms extending into the pulverizing zone a plurality of grinding balls in the raceway, and a single means mounted on each arm for performing the dual function of propelling a. hall and lifting the material passed over by the ball and depositing part of it in front of the following ball.

2. In a pulverizing mill. a pulverizing zone comprising a raceway, a plurality of revolvably mounted arms extending into the pulverizing zone, a plurality of grinding balls in the raceway, and a single element mounted on each arm and having a surface for engaging and propelling one of the balls and means for lifting the material passed over by the ball and depositing part of it in front of the following ball.

In a pulverized mill, a pulvelining'zone lit) containing a raceway, a plurality of revolvlifting the material passed over by the ball and depositing part of it in front of the following ball.

4;. In a pulverizing mill, a pulverizing zone containing a raceway, a plurality of revolvably mounted arms extending into the pulverizing zone, a plurality of grinding balls-in the raceway, and a plow pusher, mounted on each arm, having a curved front face for engaging and propelling one of the balls, and means on its under and outer faces cooperating with the raceway for lifting the material therein and depositing part of it in frontof the following ball.

5. In a pulverizing mill, a pulverizing zone containing a raceway, a plurality of revolvably mounted arms extending into the pulverizing Zone, a plurality of grinding balls in the raceway, and a plow pusher, mounted on each arm, having a face for engaging one of the balls, and a tin extending transversely of its path. of travel and rear wardly and upwardly along its outer face. 6. In a pulverizing mill, the combination of a grinding ring, a plurality of balls movable around the ring, lifting devices mounted above the ring, and a plurality of single elements revolvably mounted within the ring and performing the dual function of propelling the balls and of lifting the ma terial passed over by the balls and discharging part of it into the zone of action of the lifting devices.

7 In a pulverizing mill, the combination of a grinding ring, a plurality of balls movable around the rin lifting devices mounted above the ring, and plow pushers revolvably mounted in the ring, one plow pusher being associated with each ball, and having its front face adapted to engage the ball, and a fin extending transversely across its bottom and rearwardly and upwardly along its outer face for dislodging the material passed over by the ball, lifting part of it into the Zone of action of the lifting devices, and discharging the remainder in the path of the next succeeding ball.

8. In a pulverizing mill, the combination of a grinding ring, a ro'latably driven yoke having arms extending into the ring, grinding balls freely movable about the ring, and corresponding in number to the arms on the yoke, and a plow pusher on each arm for engaging and propelling a ball, this plow pusher having a ball-engaging face, and a fin extending transversely of its bottom curving rearwardly and extending upwardly along its outer face to its rear end, the lower surface of the tin being formed to cooperate with the ring for dislodging the material packed therein.

9. The combination with a pulverizing mill having a grinding ring and a plurality of grinding balls movable about the ring, of a plurality of plow pushers, one for each ball, each of these plow pushers having a surface for engaging and propelling the ball, and also carrying means for dislodging the material passed over by the ball and conducting it upwardly and to the rear.

10. The combination with a pulverizing mill having a plurality of grinding balls, of a plow pusher for propelling a ball, and having an upwardly and rearwardly extending fin on its outer face and a fin formed transversely of its bottom and terminating at its outer end in a rearward curved portion merginginto the transverse portion.

11. The combination of a pulverizing mill having a grinding ring and grinding balls operating in said ring, and a plurality of plow pushers, corresponding in number to the number of balls, each plow pusher having a curved front face for engaging a ball, and a fin extending across its bottom and upwardly and rearwardly along its outer face, the edge of the fin being formed to cooperate with the ring for dislodging the material packed therein and lifting it and carrying it to'the rear of the plow pusher.

12. A plow pusher for use in a pulverizing mill which has a grinding ring and a plurality of grinding balls movable about the ring, this plow pusher having a body portion, means on the forward surface of the body portion for engaging and propelling a. ball, and means on the body portion located to the rear of the said propelling means for dislodging the material passed over by the ball and lifting and conveying it to the rear.

13, A plow pusher for use in a pulverizing mill, having a grinding ring and a plurality of balls operative, therein, which comprises a body portion having a front face adapted to engage and propel a ball, and a fin extending across its bottom and upwardly and rearwardly along its outer face for dislodging, lifting and conveying to the rear, the material passed over by the ball.

14. In a pulverizing mill, the combination of a grinding ring, a rotatably mounted yoke, carrying lifting blades and a fan in superimposed relation, a plurality of arms on the yoke, a plurality of balls freely movable around the ring and corresponding in number to the number of arms, and a plow pusher mountedron each arm below the lifting blades, each plow pusher having means for engaging a ball and means for lifting the material passed over by the ball and discharging it in front of the next succeeding ball.

15. In a pulverizing mill, the combination of a grinding ring, a rotatably mounted yoke carrying lifting blades and a fan in superimposed relation, a plurality of vertical arms on the yoke, a plurality of balls in the ring corresponding in number to the number of arms, and a plow pusher mounted removably on the arms below the blades, each plow pusher having a ball-engaging surface, and a fin extending across its bottom and upwardly and rearwardly along its outer face, the edge of the fin conforming to the surface of the ring with which it is adapted to cooperate.

16. A plow pusher for use in a pulverizing mill having a grinding "ing and a plurality of balls operative therein which comprises a body portion having a socket extending downwardly from its upper face and a transverse bore passing through opposite walls of the socket, a front face adapted to engage a ball for propelling the latter, and means mounted on the body for dislodging the material in the ring and conducting it to the rear.

17 A plow pusher for use in a pulverizing mill having a grinding ring and a plu rality of balls operative therein which coinprises a body portion having asocket extending downward from its upper face and a transverse bore passing through opposite walls of the socket, an extension from the front face of the body giving the latter a shape providing a seat for a ball, and a fin extending across the bottom of the body and upwardly to the rear along its outer face.

In testimony whereof I affix my signature.

CHARLES H. BREERVVOOD.

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