Vertical roller mill

Details Vertical roller mill Vertical roller mill

1982-03-30

1984-11-20

Rosenbaum, Mark

Solid material comminution or disintegration

Apparatus

Plural rotary or oscillatory surfaces cooperate with common...

241285B, B02C 1500

Patent

active

044834870

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a vertical roller mill which can force grinding rollers against a rotary table in a very effective manner, which can be made considerably light in weight and which can facilitate inspection and maintenance.
Vertical roller mills have been widely used to grind materials such as coal or cement raw materials into desired size of finely divided particles. In general, the material fed into the casing is pulverized between the rotary table and the grinding rollers which are pressed against the rotary table to rotate in accordance with the rotary table, and the pulverized particles are carried outside of the casing by the preheated gas or the like blown upwardly around the rotary table.
The conventional vertical roller mills are divided into the "swing arm" type mill (e.g., Japanese Pat. No. 454825) and the "press ring" type mill (e.g., Japanese Patent Public Disclosure No. 125869/1977). These mills have some problems in forcing their grinding rollers against the rotary table as will be described below.
In the case of the "swing arm" type mill, a swing arm extends from a stand installed exterior of a mill casing into the interior of the casing. A grinding roller is supported at the leading end of the swing arm and pressed against a rotary table by inclining the swing arm by inclining means.
As the result, there arise the following problems.
(1) Since the stand and associated parts are installed exterior of the casing, a wide installation space is needed.
(2) Since the grinding force is applied to the grinding roller through the swing arm which is long, the swing arm must have extremely high strength against bending. As a result, the swing arms, the stand and the inclining means all become large in size and heavy in weight.
(3) Since the point of the swing arm at which acts the inclining means (that is, the point of application) is considerably spaced apart from the grinding surface of the roller (that is, the point of action), an extremely strong force is needed to press the grinding roller against the rotary table.
(4) The swing arm is inclinably extended from the exterior of the mill casing into the interior thereof so that a gap or clearance exists between the casing and the swing arm. As a result, the air leaks in large quantities into the casing so that a blower with a high capacity is required so as to discharge the pulverized particles.
In the case of the "press ring" type mill, a press ring (circular or triangular in shape) is disposed on three rollers and three hydraulic cylinders which connect the press ring to the base plate force the rollers against the rotary table.
Such mill has the following problems.
(a) Since one top ring must press three grinding rollers, it becomes large in size and heavy in weight.
(b) The irregular motion of one grinding roller adversely affects the grinding motions of the remaining grinding rollers.
(c) Since the top press ring is large in size and heavy in weight, the replacement of roller liners becomes time-consuming and cumbersome. As a result, in general, all the grinding roller liners must be replaced at the same time. As a consequence, the "press ring" type mill is not advantageous from the standpoint of economy and maintainability.
In view of the above, the object of the present invention is to provide a vertical roller mill which can force grinding rollers against a rotary table in a very effective manner, which can be made very light in weight and which can facilitate inspection and maintenance.


DISCLOSURE OF THE INVENTION

According to the present invention, brackets have their one ends connected to grinding rollers and the other ends pivoted at the side of a casing and are pulled downward at a portion adjacent to the roller mounting position, the grinding rollers being pressed against a roller table, whereby the material is pulverized into desired particles or powder between the grinding rollers and the roller table. In this way, by pulling directly downward the brackets at their portion adjacent to the roller m

REFERENCES:
patent: 3822829 (1974-07-01), Brundiek et al.
patent: 4000860 (1977-01-01), Gotham
patent: 4339086 (1982-07-01), Brundiek

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