US2709048A - Liner structure for the wall of a pulverizer - Google Patents

Description

E. A. $T'ARK LINER STRUCTURE FOR THE HALL OF A PULVERIZER 2 Sheets-Sheet 1 May 24, 1955 Filed March 1, 1952 INVENTOR 15 ME)? Ha JT/NE'K ATTORNEY May 24, 1955 E. A. STARK LINER STRUCTURE FOR THE WALL OF A PULVERIZER Filed. March 1, 1952 2 Sheets-Sheet 2 INVENTOR Elna/r A. JTfiR/f BY 44 0mm 6474M ATTORNEY United States Patent LINER STRUCTURE FOR THE WALL OF A PULVERIZER Elmer A. Stark, Worcester, Mass., assignor to Riley Stoker Corporation, Worcester, Mass., a corporation of Massachusetts Application March 1, 1952, Serial No. 274,366

7 Claims. (Cl. 241-285) This invention relates to pulverizing apparatus and more particularly to a liner to be attached to the wall of a pulverizer to protect the wall from abrasion and to enter into the pulverizing process.

Pulverizers, and particularly attrition pulverizers of the type used to reduce substances such as coal to a powder, generally comprise a rotor element revolving 1n a cyl1ndrical chamber. The wall of this chamber is Sl1b1CiI to considerable abrasion and it has been the practice to cover the wall with a series of plates or liners. These liners are usually formed with irregular surfaces that enable them to enter into the pulverizing process. Such liners have always been considered expendable and, yet, replacement requires that the pulverizer be shut down, such shutdowns are of considerably more importance than the cost of the replacement parts and are to be avoided, if possible. In the past the liners have been made of alloy cast lrons, but even the best of these required frequent replacement. Th major problem relating to the liners is that the wear ing takes place to the greatest extent on the pro ections or irregularities which serve as reaction members in the pulverizing process; this is natural enough, since the projections are designed to contact the flow of mater al to be pulverized. However, wearing on these pro ectmns destroys the ability of the liner to aid in grinding long be fore its ability to protect the pulverizer wall is threatened. The present invention overcomes these difficulties and limitations of the prior-art devices in a novel manner.

It is therefore an outstanding object of the present invention to provide a pulverizer liner which will resist wear in an outstanding manner.

It is a further object of this invention to provide a liner having extremely hard abrasion and grinding surfaces and which will contribute to maintaining the fineness of pulverization at a fixed level over a long period of time.

In addition, it is an object of the instant invention to providea liner having replaceable grinding surfaces Furthermore, it is an object of the invention to provide a liner having replaceable elements, which elements carry grinding surfaces formed of tungsten carbide and like materials.

Also, it is an object of this invention to provide a pulverizer liner in which extremely hard material is applied to the grinding surfaces.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

Figure 1 is a perspective view of the liner of the invention.

Figure 2 is a view of a face of a grinding element forming part of the invention,

Figure 3 is a view of the underside of the grinding element,

2,709,048 Patented May 24, 1955 Figure 4 is an end view of the grinding element,

Figure 5 is a plan view of the main body of the liner,

Figure 6 is a sectional view of the main body of the liner taken on the line 6-6 of Figure 5.

Figure 7 is a sectional view of the main body of the liner taken on the line 7-7 of Figure 5..

Figure 8 is a sectional view of the liner taken on the line 88 of Figure 1.

Like reference characters denote similar parts in the several figures of the drawings.

Referring first to Figure 1, which best shows the general features of the invention, the pulverizer liner, generally designated by the reference character 10, is shown as comprising a main body 11 and a plurality of grinding elements 12.

Referring next to Figures 2, 3, and 4, which constitute various views of one of the grinding elements 12, the grinding element comprises a generally rectangular plate 13 having an integral stem 14 extending from its underside. The upper side of the plate 13 is smooth and flat and has an armor consisting of two thin squares 15 of an ex tremely wear-resistant material, such as tungsten carbide, brazed thereon so as to occupy almost all of its area. One edge of the squares 15 is rounded at 16. One edge on the underside of the plate 13 is also rounded at 17. The end edges on the underside of the plate are provided with relief bevels at 21. The stem 14 is of a generally cylindrical shape and its axis extends at an angle of approximately 45' degrees to the broad surface of the plate 13. The stem terminates in a face 18 which is at a right angle to the axis and is therefore at about 45 degrees to the plate 13. The stem 14 is of circular cylindrical shape for most of its extent but merges into a flat side 19 in the area where the face 18 is closest to the plate 13. The stem is further provided with a threaded bore 20 for a purpose to be described more fully hereinafter.

Referring next to Figures 5, 6, and 7, the main body 11 of the liner is shown as of elongated, rectangular, platelike shape and having several areas of different thickness extending transversely thereacross. The entire body is slightly curved about a longitudinal axis, as is best evident in Figure 7; this curvature provides for close contact with the pulverizer wall and for the presentation of a smooth liner arrangement to the rotor. Across the ends of the body extend thin, narrow fastening portions 22 having outer corners removed at 23; the portions 22 are provided .with fastening apertures 24. Between the fastening por- 23 and extend longitudinally of the body a distance dictated by the particular arrangement of the rotor in the pulverizer. The fastening portion 27 is the thickest portion of all and is situated between the two grinding portions 26 and 28; the fastening portion 27 is cylindrieally concave, with the axis of the cylinder running transversely of the body. An aperture 30 extends through the body centrally of the portion 27 and an integral washer 31 is provided on the underside of the body surrounding said aperture. Each grinding portion 26 and 28 is formed with three steps 32, best seen in Figure 7, arranged to present these plane faces 33 which extend longitudinally of the body and at angles of 45 degrees to the general plane of the underside of the body. The valleys formed between the steps are rounded, as at 34. Entering each face 33 and passing through the body is a bore 35 which has the same cross-sectional shape as the stems 14 of the grinding elements 12; these bores extend at right angles to the general plane of the underside of the body. A shallow counter-bore 36 enters the underside of the body and is associated with each of the bores 35.

The assemblage of the grinding elements 12 in the body 11 is best shown in Figure 8. The stems 14 of the grinding elements are inserted in the bores 35 in the body; the underside of each plate 13 rests against the respective face 33 f the step 32, with the armor facing upwardly at an angle of approximately 45 degrees to the underside of the body. A bolt 37 is threaded into the bore 20 of the stem 14 of each grinding element and a washer 38 is interposed between the two. The rounded edge 17 of the grinding element fits snugly into the rounded valley 34 in the body. When the parts are so assembled, the liner 11 of Figure 1 results.

When used with a pulverizer, the interior of the chamber of the mill is covered with liners of the type constituting the present invention. The: liner is fastened to the wall of the mill with its longer dimension extending parallel to the axis. of the. mill. The rotor is rotated so that its periphery approaches and passes over the armor on the grinding elements. In other words, the squares face the oncoming hammers or other grinding elements of the rotor and the material to be comminuted is thrown against these squares. The grinding elements cooperate with the rotor in the Well-known manner. The grinding portions 26 and 28 reside in the actual pulverizing area of the. mill, while the other portions 22, 25, 27, and 29 reside in quiet, intermediate parts of the mill. It can be seen, then, that if the angle of inclination of the armored faces of the grinding elements is selected properly, the projection of the areas of the faces on a plane perpendicular to the direction in which the material is being thrown will show that no portion of the wearable body will be exposed to abrasive action. The practice of the present invention permits the use of small squares of sintered tungsten carbide, which is the only convenient shape available; furthermore, it is possible to fasten the squares on the smooth, plane face 33 of the grinding element by a special brazing technique that would not be avoidable if such a favorable arrangement were not present.

While certain novel features of the invention have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions, and changes in the forms and details of the device. illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

The invention have been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A pulverizer, comprising: a main body or" plate-like, generally elongated rectangular shape, said body having grinding portions extending transversely thereof, the grinding portions having a step-like conformation having plane faces extending longitudinally of the body and inclined to the remainder of the body, there being non-circular apertures extending through the body and opening on the said faces, and a plurality of grinding elements, eachelement Cir having an armored plate and a stem extending perpendicularly to the plate, each stem fitting and residing in one of said apertures in the body and each plate resting on the corresponding face.

2. Apparatus as recited in claim 1, wherein the plates of the grinding elements are armored with a wear-resistant material.

3. Apparatus as recited in claim 2, wherein said wearresistant material is tungsten carbide.

4. A grinding element for a pulverizer liner, said element having a plate and a stem extending at a right angle to the plate, the stem being of non-circular cross-section and having a longitudinal threaded bore.

5. A grinding element for a pulverizer liner, said element having a rectangular plate and an integral stem extending perpendicularly to the plate, the stem being of non-circular cross section and having a longitudinal threaded bore entering its free end, the surface of the plate opposite the stem being armored with plates of wear-resistant material.

6. A grinding element as recited in claim 5, wherein the wear-resistant material is. tungsten carbide.

7. In a pulverizer, a main body of plate-like shape, said body having grinding portions extending thereacross, the grinding portions having a step-like conformation having plane faces extending thereacross and inclined to the remainder of the body, there being apertures extending through the body and opening on the said faces, a plurality of grinding elements, each element having an armored plate and a stem extending substantially perpendicularly to the plate, each stern fitting and residing in one of said apertures in the body and each plate resting on the corresponding face, and means preventing rotation of the said stems in the said apertures.

References Cited in the file of this patent UNETED STATES PATENTS 741,947 Williams Oct. 20, 1903 849,781 Fuller Apr. 9, 1907 1,035,313 Buchanan Aug. 13, 1912. 1,355,335 Hasendahl Oct. 12, 1920 1,786,695 Borton Dec. 30, 1930 1,897,744 Wilkins Feb. 14, 1933 FOREIGN PATENTS 132 Great Britain of 1871 18,983 Great Britain of 1905 86,089 Sweden Oct. 15, 1934 578,292 Great Britain June 21, 1946 OTHER REFERENCES Hard Surfacing of Fusion Welding, by Howard S. Avery. Published by the American Brake Shoe Co., New York, 1.947, chapter 7, pages 4l-43. Tech. Library Designation.

TA 407A8 cop. 2. Copy in Division 55.

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