Roller mill

Details Roller mill Roller mill

1985-02-28

1986-09-16

Rosenbaum, Mark

Solid material comminution or disintegration

Apparatus

Plural rotary or oscillatory surfaces cooperate with common...

241293, B02C 1500

Patent

active

046117652

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an improvement of a roller mill in which raw material fed onto a pulverizing table rotating in a substantially horizontal plane around a vertical shaft is pulverized by compression between the pulverizing table and rotatable pulverizing rollers which are pressed toward the upper surface of the pulverizing table. More particularly, it is concerned with a roller mill which aims at reduction of vibration and improvement of pulverization efficiency.


BACKGROUND ART

Tube mill such as ball mill having a high pulverizing capability has heretofore been used for the pulverization of solid materials of a high hardness such as cement clinker and blast furnace slag. But, such tube mill is less efficient and increases the running cost and is therefore very uneconomical.
Under the circumstances, various studies have been made from the desire that the above roller mill which is relatively satisfactory in point of efficiency be utilized for the pulverization of cement clinker and blast furnace slag.
However in the case of roller mill, unlike tube mill, the pulverization of raw material is performed not by collision between pulverizing medium such as balls and raw material and by grinding, but raw material stuck between a pulverizing table and pulverizing rollers both supported by a machine frame is to be pulverized by virtue of the gripping force of both table and rollers. Consequently, vibrations of the pulverizing rollers, etc. are in many cases transferred to the machine frame, thereby creating extremely large vibrations as compared with the use of tube mill. For this reason, there are many who hesitate to use roller mill for the pulverization of very hard solid materials such as cement clinker and blast furnace slag.
Roller mill is generally considered superior in pulverization efficiency to tube mill, but the efficiency of roller mill presently available is not always satisfactory and it is considered that there is a considerable room for improvement.
Vibrations in such roller mill, above all, those induced by the vibration or pulverizing rollers, are broadly classified into (1) those attributable to the hardness of raw material or changes thereof and (2) so-called self-excited vibrations caused by slipping of raw material. The present invention aims at reducing the latter or self-excited vibration and improving pulverization efficiency. The cause of such self-excited vibration will be explained below with reference to FIGS. 1 to 5.
FIG. 1 is a sectional side view showing an example of structure of a conventional general roller mill, in which the reference numeral 1 denotes a pulverizing table which is positively rotated in a horizontal plane about a vertical axis 2 by means of a drive source such as a motor (not shown).
In the upper surface of the pulverizing table 1 is formed an annular groove 3 around the vertical shaft 2. As shown in the figure, the annular groove 3 has an arcuate section which is depressed downward.
Mounted above the pulverizing table 1 are a set of pulverizing rollers 5a and 5b whose outer periphreal surfaces 4 are opposed to and urged toward the annular groove 3 through a gap 6.
More specifically, the pulverizing rollers 5a and 5b are rotatably supported by roller shafts 9a and 9b which are inserted into a pulverizing chamber 8 through a casing 7. The roller shafts 9a and 9b are fixed to frames 11a and 11b which are swingably on horizontal shafts 10a and 10b in a vertical plane, the shafts 10a and 10b being provided outside the body casing 7. A bolt 13a (only one being shown) is threadedly secured to an arm 12a (only one being shown), and the head of the bolt 13a (13b ) is adapted to abut the frame 11a (11b), thereby setting the minimum limit of the width of the gap 6 between the pulverizing rollers 5a, 5b and the annular groove 3.
The fore end portions of the above set of frames 11a and 11b are connected so that they can be pulled by a tension device 14 and rods 15a and 15b. Consequently, the top portion sides of the frames 11a and 11b under

REFERENCES:
patent: 332488 (1885-12-01), Carhart
patent: 896954 (1908-08-01), Thomson
patent: 2689689 (1954-09-01), Engler
patent: 4067503 (1978-01-01), Broman

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