US2754068A - Roll mill for grinding liquid and pasty material - Google Patents

Description

July 10, 1956 F. PLOBERGER ROLL MILL. FOR GRINDING LIQUID AND PASTY MATERIAL Filed Aug. 22. 1952 United States Patent ROLL NIILL FOR GRINDING LIQUID AND PA'STY MATERIAL Friedrich Ploberger, Vienna, Austria Application August 22, 1952, Serial No. 305,841 Claims priority, application Austria August 24, 1951 4 Claims. (Cl. 241-222) This invention relates to a roll mill for grinding liquid and pasty material.

Grinding mills having one or several rolls have been suggested already in which one or several auxiliary rolls, to assist the grinding process, are arranged in the feed hopper and being driven in the opposite sense as the main or grinding roll are forced against the periphery thereof. In this arrangement the auxiliary rolls rotate with their peripheral surface in the material to be ground, which is situated in the feed hopper, and thus interfere with the uniform access of the material to the main rolls. For this reason the auxiliary rolls have been provided in a chamber separated from the feed hopper. The auxiliary rolls carried in correspondingly designed bearings were forced by special adjustable means against the grinding roll. This requires supervision during operation. If the pregrinding operation between grinding roll and auxiliary roll is not sufficiently effective only the sufiiciently ground part of the material to be ground can be engaged by the bar. For this reason the space between the grinding roll, auxiliary roll, and bar has been connected to the feed hopper by a duct extending round the auxiliary roll, to permit of several passes of the mate rial between the grinding and auxiliary rolls.

The known constructions do not sutficiently allow for the fact that particularly in the case of viscous or pasty substances the rolls are hardly wetted or are wetted not at all, the grinding operation being interrupted if the peripheral speed of the rolls is increased beyond a cer tain limit. The output of the mill, however, depends also on the peripheral speed of the grinding roll, which controls the auxiliary roll. For this reason high speeds are desirable.

The invention relates to a roller mill for grinding liquid and pasty material and has as its object, on the one hand, to enable high rotary speeds without disadvantage and, on the other hand, to provide for forcing the auxiliary roll under uniform pressure against the main roll, without a special device. This is achieved in that the auxiliary roll lies loosely on the main roll, under its own weight, and is secured against travelling around the main roll, and that the auxiliary roll has coordinated therewith an applying device for feeding the liquid or pasty material to be ground, in the form of liquid filaments of controllable thickness. The liquid filaments distribute evenly on the surface roll at the point of contact of the two rolls. Thus rotation of the roller within the material to be ground is prevented and wetting difiiculties are eliminated entirely.

The construction according to the invention may be developed to enable a repeated passage of the material to be ground, as in the known mills mentioned hereinthe roll 2, and

2,754,068 Patented July 10, 1956 2. ing roll defines a chamber in which the material to be ground is homogenized before being discharged from the bar. Hence, the material to be ground is subjected to pregrinding between the two rolls, to a continuous kneading in the chamber, without use of the previously employed stirring tools, and to a final grinding between the bar and the main roll. When more material to be ground is introduced into the chamber than is discharged between the bar and the main roll, the excess of material to be ground will escape from the filled chamber at the point of contact of the auxiliary roll with the wall, to be preground additionally at this point, and will be reintroduced into the chamber. Thus the grinding efl'iciency can be substantially increased.

In the drawing an example of the subject of the invention is shown schematically in vertical section. The

shaft 1 has firmly arranged thereon the main roll 2,

which is driven in the the usual manner An auxiliary roll direction of the arrow 2', and in performs a reciprocating motion too. 3 lies under its own weight loosely on while secured against travelling around the main roll 2 laterally bears against a wall 4, which serves as a guide for the bar 5, and is hollow to supply cooling water for carrying off the working heat. The bar 5 is forced against the wall 4 by several mutually spaced, two-armed levers 7, rotatable about a pivot 6. To this end, set screws 8 with lock nuts 9 are provided. The spacing of the end face of the gate 5 from the main roll 2 (entrance gap) and thus the desired degree of fineness of the grinding operation, can be altered by the set screws 10, which can be secured in position by the lock nut 11. With the wall 4 and the main roll 2, the auxiliary roll 3 defines a cavity 12. Above the auxiliary roll a reservoir 13 for the material to be ground is provided. Several mutually spaced discharge pipes 14 only one of which is shown in the drawing, with cocks or outlets 15 to control the downfiow or thickness of the filaments of material to be ground, are provided at the trough-shaped bottom of the reservoir. The pipes 14 are arranged above and along the auxiliary roll 3 so that the liquid filaments of the material come on top of the roll 3, where they distribute evenly over the peripheral surface thereof and during the rotation of the roll 3 in the sense of the arrow 3, effected by the main roll, are transferred to the main roll in the form of an even layer. Between the points of contact of the two rolls, the material to be ground is pretreated as in an edge mill, passed into the cavity 12 and thereback so that the space 12 progressively fills with mateenters the receiver. To preclude in any case a splashing away of the material to be ground, the roll 3 is surrounded by a hopper-like co tainer 16, which as contrasted With the known roll-type grinding mills Tests have shown that the grinding efiiciency can be between the two rolls the material to be treated is ground at the point of contact between the auxiliary roll 3 and the wall 4, and the material to be ground which is enclosed in the cavity 12 is subjected to rapid homogenization. If desired, the auxiliary rollcan be movable up and down in a guide so as to be secured against travelling around the main roll. Pasty material can be fed also by separate conveyor means, which feed the material to be ground to the main roll by pressure.

- lclaim:

1. In a roll mill for grinding liquid stock, the combination comprising a main roll, an auxiliary roll loosely supported on the main roll, means engaged by the auxiliary roll preventing same from traveling around the main roll and means feeding the liquid to be ground in filaments to the auxiliary roll.

2. In a roll mill for grinding liquid stock the combination comprising a main roll, an auxiliary roll loosely supported above the main roll, means engaged by the auxiliary roll and preventing same from traveling around the main roll, means feeding the liquid to be ground in filaments to the auxiliary roll, and means connected to .the feeding means and controlling the thickness of the filaments.

3. In a roll machine for grinding liquid stock, the combination comprising a main roll, an auxiliary roll loosely supported on the main roll, means engaged by the auxiliary roll and preventing same from traveling around the main roll and discharge pipes feeding liquid to be ground in filaments to the auxiliary roll and each having an outlet.

4. A roll mill comprising a main roll, a grinding bar adjacent to the main roll, a wall in guiding engagement with said grinding bar, an auxiliary roll loosely supported by said main roll and bearing against said wall, said wall, and the peripheries of said main and auxiliary rolls defining between them a chamber, and means arranged adjacent to said auxiliary roll and feeding material to be ground thereto, said auxiliary roll feeding said material to said chamber and said main and auxiliary rolls kneading said material in said chamber to homogenize said material upon rotation of said main roll References Cited in the file of this patent UNITED STATES PATENTS 20,833 Walker July 6, 1858 758,327 Macklend Apr. 26, 1904 909,275 Besser Ian. 12, 1909 2,211,824 Johnson Aug. 20, 1940 2,624,164 Donofrio Ian. 6, 1953 I FOREIGN PATENTS 217,565 Switzerland Feb. 2, 1942 355,248 Great Britain Aug. 19, 1931 355,249 Great Britain Aug. 19, 1931 391,231 Great Britain Apr. 27, 1933 526,268 Germany June 3, 1931 606,994 Germany Dec. 15, 1934 711,185 France June 23, 1931

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