US3545513A - Grinding element - Google Patents

Description

United States Patent I72] inventors Leslie Palyi 23 Larabee Crescent, Dons Mills; Nicholas Pora, 98 Banmoor Blvd., Toronto, Ontario, Canada [21 Appl. No. 759,345 [22] Filed Sept. 12, 1968 [45] Patented Dec. 8, 1970 541 oluNmNc ELEMENT 13 Claims, 9 Drawing Figs.

[52] US. Cl. 146/182; 24 l/260, 241/298 [51 Int. Cl. B02c 7/02 [50] Field otSearch 146/182, 192; 241/298, 296, 260, 92

[56] References Cited UNITED STATES PATENTS 804,738 11/1905 Kreps 241/298 583,532 1/1897 Halin 2,409,453 10/1946 Stucketal,

ABSTRACT: This specification discloses a grinding disk or milling burr of the type used in rotary disk grinders and mills for grinding up grain and a wide variety of other material, said disk having a grinding surface formed of a plurality of separate blade members spaced apart by spacer means which are replaceable for reconditioning of the grinding disk by merely removing the blade members and spacer means from a support member and replacing them with new blade members, and also discloses such a grinding disk having a particular arrangement of separate blade members incorporating teeth of graded sizes on the edge of the blade and being arranged together to form a grinding surface of a particularly effective grinding action.

PATENTEDDEB 8|97U 3545.513

SHEET 1 UF'E FIG.4

' A- //////m) .1 I j INVENTORS LESLIE PALYI NICHOLAS PORA a Mm PATENTED on: 8mm 3.545513 snm 2 OF 2 INVENTORS LESLIE PALYI NICHOLAS PORA GRINDINGELEMENT This invention relates to grinding and milling apparatusand -moreparticularly to a new and improved grinding disk or mill bur applicable toa wide variety of rotary disk grinders and mills.

Disk grinding and milling apparatus presently in: use usually incorporates complementary rotatable and nonrotatable'disk members axially displaced from one another within a housing whereinthe spacing between the disk members can be adjusted. The disk members presently in use have large grinding grinding disk for use in the grindingapparatus which-provides v a pluralityof separateremovable blades with teeth thereon separated by spacers or filler and arranged andsuppoited on a backing plate to establish a grinding face on each grinding i from .aslotted opening 19 forvarying the location of shaft 21.

member. The blades and spacers are arranged with channels formed between the blades on each grindingysurface permitting free air circulation and higher operating speeds with very little temperature rise in the blades through friction, In addition, the teeth of each blade are progressively varied with coarse teeth at the entrance to the grinding surface-and fine teeth at the outlet end of the grinding surface. Also thepgap between the grinding surfaces of the rotatableandnonrotatable'grinding members is progressively reduced from the;-entrance end to the grinding surfaceto the outlet end of the grinding surface. This permits the material to be ground to easily enter the gap between the grinding surfaces.

It is an object of this invention to provide a. grinding disk apparatus built up of separable blademembers which are easily replaced.

It is a further object of this invention to provide a diskgrindingapparatus'having an annular blade arrangement built up of separable blades of arcuate shape.

It is another object of this invention to provide'afdisk grinding member which produces little friction at thegrindingfaces thereof and dissipate heat readily.

The foregoing and otheradvantages. will become} apparent from the following description of the preferredembodiment of nally threaded holes 42 to receive a screw member 43 to lock the invention which is here given by way of an examplewith v reference to the following drawingsand 'in whichlike reference devices refer to like parts thereof through the various views and diagrams, and in which:

FIG. 1 is a perspective view of a typical diskgrinder-partly cut away embodying the features of the invention;

FIG. 2 is a plan view of a portion of the grindingdisk embodying the features of the invention;

1 FIG. 3 is an enlarged perspective view of a segment of the disk of FIG. 2 partly cutaway;

FIG. 4 is a sectional view along4-4 of'FIG. 1;

FIG. 5 is an enlarged perspective view of a blade and spacer according to the invention;

. FIG. 6 is a plan" view of a blade and spacer;

FIG. 7 is a schematic viewshowing a preferred arrangement of blades and spacers;

FIG. 8 is a plan view of an alternative embodiment; and

FIG. 9 is a section along'the line 9-'9 of FIG.I2,.greatly exaggerated.

The disk grinding anparatus is illustrated; in ,FlG.1 ,.and

generally indicated as 10, beinga typical grinder of-xwell- Lever.20 is located at the bottom of hopper 16 for controlling the rate of flow of feed therefrom by conventional means (not shown). 1 V

Within the casing 11 is an electric motor M with an output shaft2l which extends through the casing .11 and a free end 22 almost touches the wall of the casing 12. The free end'22 is threadedto receive thereon'a mounting plate 23. A rotatable grinding'member 24 is connected on the mounting plate 23 by bolts 25. A nonrotatable grinding member 26 is connected on the. casing 11 by similar bolts (not shown). Connected axially around the output shaft 21 is an annular plate 27 having three impellers .28 extending outward from the plate 27 for distributing .ungroundfeed therearound, A central opening 29, through casing portion 11 permits passage of feed from hopperl6.

. According to the i'nvention'the grinding members 24 and 26 .each comprise an annularring 30 with an axial opening 13 therethrough and spaced apart parallel side surfaces 32 and 33 xwith a machined-out recess 34 in one side surface 32, as shown best in FIG. 3. The recess 34 has a bottom wall 35 and two side walls 36 and 3 7.'The bottom wall 34 is not parallel to the side surfaces 32 and 33 and is slanted. The side wall 36 ex- :tends from the side surface 32 to the bottom wall 35. The side awall-37 isformed with a channel 38 adjacent the bottom wall .Within' the recess 34 arepositioned on the bottom wall 35 ,alternategrinding blades. 39 and spacers 40 extending out of therecess :34 approximately normal to the side surfaces 32 and 33, asshown in FIG. 2, filling the entire recess 34 around its fullextent. An. annular member 41 is positioned in the recess34 and makes contact with the side wall 36 to secure the blades 39 and the spacers 40 in position. Between the annular ring130 and annular member 41 are a plurality of intertheannular member 41 to the annular ring 30.

Each blade 39comprises the body portion 44, a bottom edge 45 and an upper edge 46 spaced apart therefrom, inner .andvouterends tland 48 join the bottom edge 45 to the top edge-46. Extending outward from each- end 47 and 48 are -innerrand outer lugs49 and 50. On the top edge 46 of the blade 39 are .cut teeth 51, preferably of varying pitch, the

'teethf5lat the inner end being'of, for example, 4 pitch while 'width of the blade and the fine teeth cuttingmore or less in line with the blade.

Alternativelythe blades 39 may extend diagonally from the entrance end of the grinding member to the outlet end of the grinding member. The blades 39 onthe rotatable grinding :member 24 and the nonrotatable grinding member 26 oppose one another as shown in FIG. 2, so that when inposition the blades 390i: the grinding member 24 cross the blades 39 of the nonrotatable grinding member 26 at a large number of predeterminedintersections. The blades 39 crossing causes :t'he-material therein to be ground up.

The spacers 40 have a similar structure as the blade 39 with lugs 49 and 50 except for the height of the body portion 44 which is lower and there are no teeth therein. One or more 1 spacers340' are placed between adjacent blades 39 in one embodiment of the invention, to give air channel between the blades 39. The numberof spacers 40 to be used between the blade 39depend on the desired separation between the blades .39, two ormore spacers 40 providing a greater air space and hence improved cooling. A filler material may be substituted be ground.

In operation, the electric motor is operated to rotate the shaft 21 and the rotatable grinding member 24 attached thereto at the free end 22 in a clockwise manner. The nonrotatable grinding member 26 is fixed to the casing 11 and does not rotate. The rod 18 is connected to a mechanism (not shown) which permits the operator to vary the gap distance between the rotatable grinding member 24 and the nonrotatable grinding member 26 such as by sliding shaft 21 in and out. This will permit the operator to select to what mesh the material should be ground to.

The material is fed into the inlet hopper l6 and passes through the opening 29 in the casing portion 11 and opening 31 in member 26 flowing around shaft 21 and enters the area at the entrance end of the grinding members 24 and 26 where it is distributed and gradually 'be fed between grinding members 24 and 26 by impellers 28, with the member 24 rotating clockwise. It will be understood that the teeth 51 of the blades 39 are separated further apart at the inner ends of blades 39 than at their outer ends by reason of the slanted bottom walls 35 of the recesses 34, and furthermore, that the teeth 51 at such inner ends are relatively of a coarse pitch, and the teeth at the outer ends are of a fine pitch, and are progressively graduated therebetween along the length of blades 39. In this way, it is ensured that even relatively coarse material can freely enter between members 24 and 26 at their inlet ends, and as such material is progressively moved by the centrifugal movement of member 24 in an outward manner, the material becomes more and more finely ground in a gradual progressive manner as the teeth 51 become closer and closer together 7 and as their pitch (i.e. fineness) increases. In addition, it will be noted that by reason of the arcuate shaping of blades 39, which arcuate shaping is arranged on members 24 and 26 respectively to be directed in an opposite direction, the inner ends of the blades 39 will pass one another in a more or less radial manner, the intermediate portions of blades 39 will pass over one another at intersecting angles which become progressively greater, towards the outer end of the blades 39, and,at the outer ends of the blades 39, they will pass one another while alined in an almost circumferential manner. At each of the intersections, a progressively finer grinding action takes place in a predetermined manner and as a result the material is gradually brought down from a coarse grade to a time uniform mesh. Simultaneously with the aforesaid grinding action, a'certain degree of air is entrained in the channels defined between adjacent blades 39, by reason of the impelling action of the rotating impellers 28, and also by reason of the centrifugal action of grinding member 24, and the passage of such air both materially increases the efficiency of the grinding by causing a constant outward flow of finely ground material which is entrained with such air, and also maintains an even temperature in the blades 39 and members 24 and 26, thereby avoiding any deterioration of the material during grinding. 7 A

In some cases, it may be desireable to provide a somewhat more gentle grinding action, depending upon the particular type of material being ground. In this case, it is possible to obtain such a change by merely reversing the direction of rotation' of the rotating grinding member 24. In this case, the grinding member 24 may be rotated anticlockwise so that the outer ends of the blades 39 are directed in a trailing manner. In this case, the intersections of the blades 39 will obviously take place at the same place, but at the material to be ground is fed in between the members 24 and 26, the anticlockwise rotation of member 24 causes the material to be ground to pass between blades 39 in a different manner, whereby a smoother grinding action take place.

It is found by experience, tl1at blades 39 will provide a very much longer life for effective grinding operation than the conventional grinding disk of the prior art in which the teeth are out directly into solid metal in the disk In addition, when the teeth 51 of blades 39 do become blunt, all that is required is to remove the ring members 30, release the annular members 41 and remove the blade 39. New blades 39 can then be inserted and annular members 41 replaced and the grinding members 24 and 26 are then ready for further use. In addition, it is apparent that such renewal of grinding members 24 and 26 can be done by totally unskilled labourv all that is required, is a supply of new blades 39. This is to be distinguished from the practice in the prior art where the dressing of grinding stones was considered to be a very highly skilled task requiring many years of apprenticeship.

In addition to the foregoing, many other variations in the type of grinding effect produced can be obtained by varying the shape of blades 39 and spacers 40. With reference to FIG. 7, this schematic illustration shows one preferred form of calculating the required radius of are for the blades 39 and spacers 40. In FIG. 7, R represents the outside radius of the ring member 30 and radii r represents the inner radius thereof, such radii being measured with reference to the maximum width of the recess 34.

It will be understood that the length and radius of are, or other shaping, of saw blades 39 and spacers 40 may be varied in a number of ways. There are various factors which must be taken into consideration however. With reference to FIG. 7, it is quite clear that the circumference of the circle R is very much greater than the circumference of the circle r, and this is obviously a major factor to be taken into consideration when considering the shaping and arrangement of the blades 39 and the spacers 40, since, depending upon how they are made and arranged, they will tend to be spaced somewhat apart from one another at the circumference of R, notwithstanding the fact that they are tightly packed together at the circumference r. FIG. 9, shows in greatly exaggerated form the effect of this tendency, which is to be compared with FIG. 3, which shows the blades 39 and spacers 40 closely packed together. A certain degree of spacing between the blades 39 and spacers 40 is considered desireable according to the practice of the invention, at least towards their outer ends adjacent the circumference of the circle R, since this provides a spring action to the blades 39 which is found to somewhat increase the efficiency of the grinding operation. Preferably, the spacing between the blades 39 and spacers 40 may be varied somewhere between one and five one-thousandths of an inch for the grinding of wheat and the like, or although when grinding other materials, this may not necessarily be desireable. Obviously, such a relatively small spacing at the outer ends of blades 39 and spacers'40 cannot be achieved if the blades and spacers aremade completely straight, and in fact, the use of a substantial degree of curvature in the blades 39 and spacers 40 is found to very much reduce the spacing between them at their outer ends, to somewhere within the acceptable range. This effect is obviously maximized by arranging the blades 39 and spacers 40 around quite a substantial are, up to or of are, by means of which the inner ends of the blades 39 and spacers 40 at the circumference of the circle r lie in a more or less radial manner, and the outer ends of the blades 39 and spacers 40 at the circle R lie in a more or less tangential manner relative to the circumference of the circle R. In this way, the blades and spacers 39 and 40 occupy the minimum of space around the circumference of the circle r, and occupy the practical maximum of space around the circumference of the circle R. However, as stated above, it is not necessarily found to be desirable to achieve a perfect geometrical, arrangement of the blades 39 and spacers 40 which would eliminate the spacing between their outer ends, some flexibility of movement being found to improve the grinding action as stated above. In addition, it is found that it is desirable to make blades 39 and spacer 40 having different arcs for different grinding applications. In fact, it is found to be desirable that the radius of arc of the blades 39 and spacers 40 should, to a certain degree, follow the accepted teaching in the art of dressing grinding stones and disk (see for example a handbook entitled Malomipar Gyakorlati Muszaki Szakkonyv published by Malomujsag (Milling Magazine) Kiadasa, Budapest, V., Hollan-Utca 9, in November, 1942, from pages 96 through to Thus,.according to such prior art teaching in relation to dressing grinding disks one acceptable method calculating the radius of arc of theblades 39 and spacers 40 is shown roughly in FIG. 7. According to this method, the circles of radius R and r are drawn out as shown, and an additional circle of radius r/x is drawn, in this case equal to somewhere about 0.75 percent, of R and, without changing this radius, a series of arcs are drawn in, between the circles r and R, from centers spaced around the circle r/x. Obviously, by varying the fraction r/x various different blade shapes can be drawn in, the more pronounced curve in the blade being generally desirable for grinding of finer material, and the straighter blades being desirable for coarser materials.

In some cases, it may be desirable to use blades 39 which are spaced further apart, in which case spacer 40 can be used doubled up, or can be made of thicker material, or, as shown .tachment ring in a generally radial manner at their inner ends,

I and meet said outer attachment ring in a nonradial manner.

in FIG. 8, the blades 39 can be separated by specially shaped or moulded spacers 40a, alternatively these spacers 40a can be formed of some form of thermo setting material such as babbitt metal or the like, as stated above, In this case, it is possible to use an even wider variation in the shaping of the blades 39 since obviously the use of such thermo setting material will accommodate any spacing, and any variation of spacing between the circles r and R which may occur without any problem.

ln order to assist in the grinding of coarse material it may sometimes be desirable to cut a series of crescent shaped grooves or indentations by use of suitably shaped carborundum wheel, into the face formed by the blades 39 and spacers 40 much in the same manner as was formerly practised in the art of dressing grinding stones and disks, such indentations being omitted from the drawings for the sake of clarity.

in addition there may be added, if desired, a small band of circular blades (not shown) extending around the periphery of each of grinding members 24 and 26 to provide afurther fine grinding effect, although generally this is unnecessary.

The foregoing is a description of a preferred embodiment of the invention only and is given here by way of example. The

invention is not to be taken as limited to any of the specific features described, but comprehends all such variations thereof as come within the scope of the appended claims.

We claim:

l. A grinding disk for use in association with disk grinding apparatus of the type having a rotary grinding disk and a stationary grinding disk wherein the material to be grounded enters between the disks from a central aperture extending through oneof the disks, and comprising:

a generally cirrular support member;

inner and outer attachment ring means on said support member;

annular supporting platform means extending between said inner and outer attachments means on said support member;

a plurality of separate blade members extending between said inner and outer attachment ring means and having grinding teeth formed on one edge thereof; and

spacer means between said blade members.

3. The apparatus as claimed in claim 1 wherein said support member comprises an annular disk: having a central aperture therethrough, a recess formed in one side face of said disk and extending therearound in an annular manner and defining inner and outer wall means on either side of said recess and a supporting floor extending therebetween, said inner and outer wall means. i i

4. The'apparatus as claimed in claim 1 wherein a portion at least of one said attachment ring; means is removable for removal and replacement of said blade members.

5. The apparatus as claimed in claim 1 wherein said blade members have inner and outer ends, and including teeth formed along one edge of said blade means of varying size the teeth at the inner en thereof being relatively coarse, and the members and spacer means are held firmly together around said inner attachment ring means, and are spaced apart from one another towards said outer attachment ring means.

8. The apparatus as claimed in claim 1 wherein said blade members have inner and outer ends, and including retaining tongue members extending from said inner and outer ends for interengagement by and with said inner and outer attachment ring means. i

a 9. The apparatus as claimed in claim 1 wherein said blade members and spacer means are arranged one beside the other,

alternatively around the entire extent of said support member.

10. The apparatus as claimed in claim 1 including additional blade members arranged to form an annular band located and spaced outwardly from said separate blade members and spacer means. i

1l.The apparatus as claimed in claim 1 wherein said blade members and spacer means are arranged with a plurality of said blade members adjacent to one another in groups, each said group of blade members being separated by spacer means.

12. The apparatus as claimed in claim 1 wherein said spacer means comprise sheet metal members out and shaped to conform to the shape of said blade members and having inner and outer ends, and incorporating inner and outer tongue means for interengagement by and with said inner and outer attachment ring means.

13. The apparatus as claimed in claim 1 wherein said spacer means comprises any suitable material having a plastic phase and a solid phase, said material being poured between said separate blade members while in said plastic phase and allowed to set in said solid phase.

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