US2977056A - Colloid mill with pre-cutting attachment - Google Patents

Description

March 28, 1961 K. H. GUSTKE COLLOID MILL WITH PRE-CUTTING ATTACHMENT Filed Nov. 8, 1956 5 Sheets-Sheet l 4 u "u \l INVENTOR.

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HUI Hwwwflwnw \l T n. Q i IIT 5 \7/ :13 r J m. 6 7w 1 m II, t 7 Afr 1 K s d w COLLOID MILL WITH PRE-CUTTING ATTACHMENT Klaus HerbertGnstke, Rastatt, Baden, Germany, assignor to Probst & Class, Rastatt, Baden, Germany, a firm of Germany Filed Nov. 8, 1956, Ser. No. 621,141

Claims priority, application Germany Nov. 16, 1955 2 Claims. (Cl. 241-101) The present invention relates to colloid mills with grinding rotors mounted in stationary housings, and more particularly to means attached to the inlet portion of the mill for preparing the material to be milled by pre-cornminution.

Colloid mills operate with suitably shaped and arranged serrated grinding discs or bodies of silicon carbide or special steels. In such known mills, the adjustment of the comminuting space or gap defined between stationary and rotating conical grinding elements may be effected, for instance, by axially moving the elements in relation to each other, the fineness of the milling depending, in part, 011 the width of the comminuting gap. Colloid mills of this type have been used for finest comminution, homogenizing, dispersing, and emulsifying of different materials. However, the grain size of the material to be comminuted may not exceed certain dimensions (for instance, about mm. in diameter), depending on the composition and tenacity of the material to be ground. Therefore, to avoid clogging and stoppage of the mill, it is very often necessary first to coarsely comminute the material in a special crushing mill before it can be ground in the colloid mill.

It is the principal object of the present invention to provide effective, efficient and economical means to prepare material for comminution in a colloid mill.

It is a more specific object of this invention to provide a demountable attachment at the inlet portion of a colloid mill for pre-cutting or pre-cmshing material to be ground therein.

It is a further object of the invention to mount such a p re-cutting or pre-crushing attachment in such a manner that it may be easily mounted and detached by an operator.

It is also an object of the invention to drive the precutting or pre-crushing attachment directly by the shaft which rotates the grinding rotor.

It is another object of the invention to mount the precutting or pre-crushing arrangement so that the comminution space or gap of the colloid mill may be adjusted without interference by the attachment.

The above and other objects, features and advantages are accomplished in accordance with the present invention by detachably mounting a pre-cutting or pre-crushing device at the inlet portion of a colloid mill and operating the device directly by an extension of the rotating shaft of the mill rotor.

The invention will be more fully explained in conjunction with the following detailed description of certain Ice Mensa Mar. 28,1961? Figs. 2a and 2b show convex and concave surfaces, respectively, of the base plate;

Fig. 3 is a top view illustrating certain details of the base plate and knife holders of the embodiment of Fig. 2;

Fig. 4 is a perspective view of the paddle wheel c0nveyor; 7

Figs. 5 and 6 are transverse sections of the knife and apertured base plate; 7

Figs. 7 and 7a show a detail of the apertured base plate with an oblique aperture and tooth;

Fig. 8 illustrates a horizontal colloid mill; and 1 2 Figs. 9 and 9a show a detail of the apertured base plate with an oblique aperture. V

The top portion of the colloid mill itself, which forms no part of the present invention, is schematically illustrated. The colloid mill may, but need not be, of the general type shown in U.S. Patent No. 2,749,053 or in- U.S. patent application Serial No. 562,542, filed January 31, 1956, by Klaus Gustke and Erich Kuhls, and includes 9 to receive the material to be ground from the inlet.

portion of the mill. As is known per se, the grinding rotor portion 7 has apertures in its walls through which the material to be ground is thrown into the comminuting gap be centrifugal action. Rotor portion 8 is'keyed or otherwise fixedly mounted on operating shaft 10 whichis rotated by a power source, such as a motor (not shown); The ground material leaves the comminuting gap by mill outlet 11. All of this structure is known'per se and forms no part of the present invention, except inasmuch as it cooperates with the pre-comminuting or cutting device presently to be described.

For the purpose of mounting the pre-cutting or precrushing attachment in the inlet portion of the mill, an extension shaft 12 is fixedly connected to and rotated with operating shaft 10. The extension shaft, which also carries and rotates grinding rotor portion 7, may be connected to shaft 10 by any suitable means, such as by a threaded or wedged joint. Extension shaft 12 carries and rotates rotating knives 13 and 14 of the pre-cutting device, as will be more fully described hereinafter.

A different connection between the operating and extension shafts is shown in Fig. 1a. Here, shaft 10ais connected with shaft 12a by means of a mortise-and tenon joint, shaft 12a carrying the pre-cutting structure without the interposition of a sleeve 29 being keyed to the shaft, as in the embodiment of Fig. 1.

In the embodiment of Fig. 1b, the mortise-and-tenon joint of Fig. la is replaced by splines 32.

As shown, the pre-cutting device is mounted in a hous An apertured base plate 22 is arranged between knives 13 and 14 andreplaceably mounted between flanges "17 and 20, respectively, of housing portions 15 and 18. Base plate 22 is held against rotation by one or several pins 1 ereby t p ate is a ache to flan e 17 .Eh top and bottom portions 'of thelfdusing are detachably connected by wing screws 23 or similar connecting devices which can be easily connected and disconnected. Base plate 22 may be mounted on extension shaft 12 by means ofball bearings'24 although no such bearing may be necessary, depending on the type of shaft used.

' Fig. 2 illustrates a different embodiment of the base plate; As shown in the drawing, the plate comprises two portions 22a and 22b, each provided with holes or slots 25a and 25b, respectively. By rotating the two plate portions in relation to each other, the holes'of the respective portions may be brought into and out of registration, thus serving to narrowor widen the passages through which cut material may pass. Thus, the desired grain size may be regulated even during the pre-comminuting step. Otherwise, the base plate of Fig. 2 operates in the same manner as the single plate illustrated in Fig. 1.

As will clearly appear from the drawing, top portion 18 of the pre-cutting device housing may be easily detached and, after removal thereof, the entire pre-cutting device assembly may simply be lifted off the extension shaft 12. After the pre-cutting device is thus removed, the housing top portion 18 may be replaced in position and the colloid will operate without a'pre-cutter when material is charged into the mill through hopper 28 attached to the top of portion 18 in communication with aperture 19 thereof.

As shown in Fig. 1, the pre-cutting device assembly comprises a sleeve 29 keyed to the extension shaft 12 at 30. The removably mounted sleeve 29 carries knife holder 26 arranged above the base plate and holding knives 13 as well as impeller or paddle wheel 27 (see also Fig. 4) arranged below the base plate, the impeller carrying knives 14, if desired (see Fig. 1). The knife holder is keyed to sleeve 29 at 261 and may be axially moved on the sleeve by adjusting the screen cap 31.

Fig. 2a is identical with Fig. 2, except that the plate portions 22a and 22b have convexly curved surfaces.

Fig. 2b is similar to Fig. 2, except that the base plate 22:; consists of a single portion (like the plate shown in Fig. 1) which has concave surfaces, giving the plate a saucer-like appearance. Also, there is only a top knife 13 and no knife below the base plate, the pre-comminuted material falling through the base plate being seized by paddle wheel 27 and directed to inlet 9.

Fig. 5 is a transverse section through knife holder 26 attached to knife 13 by means of threaded bolt 33. 'As shown, the knife holder has a pointed edge 34 which seizes and cuts the coarse material fed through hopper 28 and then directs this 'pre-cut material to the cutting edge 35 of the knife which is formed with a concave channel 36.

Fig. 6 shows a knife of the identical shape but, in this instance, the knife holder and knife form an integral unit. Also, the apertures in base plate 22 are obliquely inclined instead of being vertical, as in the arrangement of Fig, 5. Fig. 7a is a plan view of an oblique base plate aperture with recess 37.

' Fig. 7 is a cross-sectional view taken along the line 7--7 of Fig. 7a.

Fig. 9a is a plan view of another oblique base plate aperture and Fig. 9 is the cross-sectional view taken along the line 9-9 of Fig. 9a.

As shown in Fig. 3, the position of the knife holder 26 may be radial (26a), tangential (26b) or spiral (26c). Knives 13 are so arranged that they have actually two cutting edges 34 and 35, one of which seizes the material to be ground, presses it against base plate 22 and pre-cuts it, while the other cutting edge glides along base plate 22 and cuts the material as it enters the apertures in the plate. Fig. 3 also shows that'the surface ofthe base plate may be serrated or otherwise roughened to further the pre-cutting and pre-comminuting effect.

Paddle wheel 27 on the opposite side of base plate 22 .maycarry knives '14 in engagement with the base plate as shown in Fig. l. The lower knives may be omitted as shown in Fig. 4. The material passing through the apertures in the base plate is again comminuted or cut Where knives 14 are provided. Knives 14 may be positioned similarly as knives 13, i.e. radially, tangentially, or spirally. Paddle wheel 27 is somewhat similar to a snail which tapers downwardly, the paddles replacing the turns of the snail housing. The structure of the paddle wheel serves as a screw conveyor for the pre-cut material to the colloid mill proper. Paddle wheel 27 as well as knife holder 26 may be keyed or wedged to sleeve 29 so that they may be axially adjusted at will if such adjustment is desirable due to a corresponding adjustment of the comminuting gap in the colloid mill, for instance. Only base plate 22 is fixed against axial movement by being mounted etween flanges 17 and 20 of housing portions 15 and 18 so as to fix the position of knives 13 and 14 in relation to the base plate.

Base plate 22 may have the form of an annular disc, as shown in Fig. 1, or it may be frusto-conical, as illustrated in Fig. 2. It may also have a concave (Fig. 2b) or convex (Fig. 2a) surface. Convex base plates are used when the material to be ground is to be given a specific direction or if space conditions force such a structure since it is evidently desirable to make the cutting surfaces as big as possible without increasing the dimensions of the precutting device unnecessarily.

As will be clear from the above description, the appa ratus operates as follows:

Material to be milled is charged through hopper 28 into the pre-cutting chamber and is cut therein by rotating knives 13. The cut material passes through the apertures in base plate 22, is seized by knives 14, and is again comminuted. Paddle wheel conveyor 27 transports the precomminuted material into cavity 9 of the rotor portion 7 wherefrom it is centrifugally thrown into the comminuting gap. The finely milled material leaves the comminuting gap by outlet 11.

If and when it is desired, the comminuting gap may be adjusted by rotation of adjustment ring 6 without interference by the pre-cutting attachment. If no precutting is needed, cover portion 18 is lifted and sleeve 29 carrying the pre-cutting device is removed from extension'shaft 12, whereby the colloid mill may be charged and operated without pre-cutting of the material.

While the mill has been described as an upright mill, it will be evident that it could operate identically in horizontal position, as illustrated in Fig. 8. In this mill, the cover portion 18a has the shape of a funnel to direct the material fed through hopper 28a to the pre-cutter. The pre-cutting and milling arrangement is identical with that illustrated in Fig. 1 and need, therefore, not be described again. Bevel gearing 40 in gearing box 29 connects operating shaft 10a with shaft 41 of electric motor '38. Obviously, the electromotor itself could also be horizontally mounted with its shaft in alignment with operating shaft 10a, in which case the bevel gearing would be eliminated.

As will be seen from the above, the apparatus of the present invention provides a single machine wherein milling may be continuously effected from the stage of large particles to the very finest grains without interruption, the desired fineness being adjustable by regulating the comrninution gap in the colloid mill itself. Thus, the pre-cutting attachment replaces a separate coarse precu'tting machine. In view of the easy attachment and detachment of a few elements only, such an apparatus has the further advantage of being usable as a colloid mill, 'when the pre-cutter is detached, and a crushing mill, when'the pre-cutter is attached and the comminution gap, is opened wider. Any in-between adjustment can equally simply be effected. If desired, the apparatus may be built into a conduit system to receive and discharge material from and to pipes in communication with the mill inlet and mill outlet.

While the invention has been clearly described and illustrated in connection with certain preferred embodiments, it will be obvious to the skilled in the art that many modifications and variations may be effected, particularly after benefiting from the present teaching, Without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A mill comprising, in combination, a mill housing, a stationary frusto-conical annular milling element axially slidably mounted in said mill housing, a rotary frustoconical milling element mounted Within said annular milling element, a comrm'nuting gap being formed between said milling elements, the rotary milling element defining a central inlet cavity for material to be ground in said comminuting gap, the material being centrifugally thrown into said gap through aperturesin the rotary milling element upon rotation of the rotary milling element, shaft means journalled in said mill housing for rotatably mounting the rotary milling element, an extension shaft fixedly connected to said shaft means and rotatable therewith, rotary adjusting means connecting the stationary milling element with said mill housing for regulating the axial position of said element thereby to control the width of the comminuting gap, a stationary casing mounted on,

said stationary milling element above said adjusting means, a cover removably mounted on said casing, the casing and cover forming a housing, said extension shaft extending through the inlet cavity into the housing, a removable sleeve member keyed to the extension shaft for rotation therewith, a non-rotatable apertured base plate mounted on the sleeve member between the casing and the cover, knife means keyed to said sleeve above the base plate for rotation with the sleeve, and knife means keyed to the sleeve below the base plate for rotation with the sleeve, both knife means cooperating with the base plate for shearing action therebetween.

2. A mill comprising cooperating stationary and rotary milling elements forming a comminuting gap therebetween, shaft means rotatably mounting said rotary milling element, inlet means for feeding material to be ground to the comminuting gap, a shaft extension fixedly connected to said shaft means and rotatable therewith, a stationary casing mounted on said stationary milling element, a cover removably mounted on said casing, the casing and cover forming a housing, said shaft extension extending through the inlet means into said housing, and cutting means detachably mounted on the shaft extension in said housing, the cutting means comprising an annular apertured base plate mounted against rotation about said 1 shaft extension and between the casing and the cover,

and knife means mounted on the shaft extension for rotation therewith on at least one side of said base plate, the knife means cooperating with the base plate for shearing action therebetween, and comprising a knife holder keyed to the shaft extension above the base plate and a plurality of knives in said knife holder, and a paddle Wheel material conveyor keyed to the shaft extension below the base plate, said paddle wheel carrying a plurality of knives with cutting edges cooperating with the plate and knife ends conforming to the casing.

References Cited in the file of this patent UNITED STATES PATENTS 14,002 Stout Dec. 25, 1855 746,275 Bowsher Dec. 8, 1903 1,687,886 Phillipp Oct. 16, 1928 2,734,728 Myers Feb. 14, 1956 2,749,053 Rieth June 5, 1956 2,840,318 Schnell June 24, 1958 FOREIGN PATENTS 471,848 Canada Mar. 6, 1951 534,013 Belgium Dec. 31, 1954

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