FR2464096A1 - CYLINDERS MILL AND METHOD FOR OPERATING SAME - Google Patents

Abstract

A. CYLINDER CRUSHER, IN PARTICULAR FOR CLAY ROCK, WITH TWO INDIVIDUALLY ACTUALABLE CRUSHING CYLINDERS PER MOTOR, IN THE OPPOSITE DIRECTION, AND PRESENTING CRUSHING TEETH. B. CRUSHER CHARACTERIZED IN THAT EACH CYLINDER 1, 2 IS EQUIPPED WITH A REVERSIBLE HYDROSTATIC CONTROL 12, 13, 14; 22, 23, 24 WITH PARTS TO LIMIT THE DRIVING FORCE BY LIMITATION OF THE PRESSURE OF THE MOTOR FLUID AND AUTOMATIC PARTS TO AUTOMATICALLY REVERSE THE DIRECTION OF ROTATION OF THE CYLINDERS AND TO RESET THE PREVIOUS ROTATION, AFTER A PERIOD D 'PREDETERMINED INVERSION. C. CRUSHER APPLICABLE TO THE CRUSHING OF CLAY ROCKS.

Description

e.- The invention relates to a roll mill, in particular for rock

  argileuse, with two grinding rollers individually actuable by motor, in opposite directions,

  and having grinding teeth.

  Roll mills are usually driven by mechanical transmission transmitting on

  cylinders the movement produced by a motor.

  Hydraulic couplings are also frequently used to overcome mass inertia at the moment

  These hydraulic couplings are also prescribed

  for some protection in case of emergence of forces

  too high on the grinding teeth. But it is their gener-

  it is impossible to meet this requirement because

of inertia prevents them.

  Couplings with safety bolts are generally used as protection devices. In the case of clay rock with a thick rock content, it appears

  relatively often overloads, which lead to shear

  These bolts result in undesirable downtime. It follows that the staff mounts

  safety bolts stronger, and finally, it is the trans-

  mission and the tree that are destroyed.

  It can usually be said that known roll mills clog relatively often, especially when grinding on site in a quarry or mine and the mill is fed with relatively small rocks and in any case muddy, which is the case in winter and in bad weather. However, direct grinding in the quarry or farm has the advantage that a pre-digestible mixture can be obtained that can be stored for aging, without disturbances occurring in the field.

the operation of the mill.

  The object of the invention is to eliminate the existing defects and to propose a roll mill, which makes it possible to grind, even clayey rocks, cleanly and without

  major interruptions in the operation.

  To solve this problem, the invention proposes a roller mill characterized in that each cylinder is equipped with a reversible hydrostatic control with organs to limit the driving force imitation of the pressure of the engine liquid, and automatic devices to automatically reverse the direction of rotation of the cylinders and to restore the previous rotation, after the flow of a

  predetermined inversion period.

  It is known for roll mills to drive the two rolls with a number of turns less than 50 turns per minute and with a different number of turns for each. This basic principle can also apply to the invention. A rotation of the cylinders of 33 and 25 rpm for example for the one and the other cylinder, was

Revered advantageous.

  In the case of the hydrostatic control, there is, on the one hand, a pressure relief valve, and on the other hand, a pressure-activated switch which stops the advancement of the cylinders, as soon as a predetermined maximum pre-emerges. As opposed to the usual controls, the hydrostatic control can act directly on each cylinder, so that with the pressure limitation described, it appears

  an instant effect. Overloads are not to be feared.

  With an automatic reversing member it is possible, preferably after a certain period when the maximum pressure has been kept at a standstill, to trigger an inverted movement of the rolls, which is maintained for several seconds and in any case during several rotations of the rolls, until the automatic restoration of the normal direction. If a "jamming" occurs again, this process can be reiterated

several times.

  So, the pieces that caused the "jamming" can not only be released, but they can be brought,

  by inversion, in another position.

  The transient maintenance of the maximum pressure

  when stopped, prior to the inversion, prevents successful overloads in other known grinders, but the stuck piece is not released as quickly as

  grinders, so that the pressure can act

  and break a piece, which would have resisted the

  short-term cation of the same pressure.

  The device according to the invention and the method for its operation can almost completely exclude overload interruptions, so that the output is

significantly higher.

  The advantageous structure of the grinding teeth, characterized in that they have a sawtooth configuration, and that they comprise, between their stiff attack stop

  and their inclined rear edge, a summit ridge of which

  lure is at least approximately circumferential, also acts in this sense. Likewise, the cutting edge of the teeth, in the shape of a wedge-shaped blade, reinforces this action and prolongs the

  life of teeth and other parts of the mill.

  The construction of the roll mill according to the invention can be avoided by the fact that the cleaning combs are provided only in the upper zone. However, if a temporary obstruction is formed, it can be eliminated through the upper side cleaning holes. An obstruction can be prevented almost completely even under unfavorable operating conditions when an evacuation hopper is designed. as a carrier with oscillatory movements. The invention will be better understood with regard to

  schematic drawings, in which the figures represent

  FIG. 1 is a side view of a roll mill according to the invention, with partially illustrated lateral formwork, and a partially represented drive motor; FIG. 2 is a plan view of this roll mill with a hopper, 3, an enlarged sectional view with respect to FIG. 1, in a vertical plane through the

roll mill.

  The roll mill shown has two mill rolls 1, 2 each provided with milling teeth 20. These teeth 10, 20 fit at a time into one another during the rotation of the rolls 1, 2 then than

  Figure 3 represent them in recovery.

  The de-grinding teeth 10, 20 each comprise, a steep forward edge and blade-shaped 101, 201, an inclined rear edge 102, 202, and between these edges, a relatively long edge 103, 203 whose course follows the direction of the circumference. In normal forward movement along the arrow of FIG. 3, the front edges 101, 201 of the crushing teeth 10, 20 reach the rock to be ground. In the case of inverted movement, the stuck rock pieces and other materials are lifted by the inclined posterior edges 102, 202, and moved. The long peak edges 103, 203 are an important factor for the strength of the teeth, without

we know exactly why.

  In the vicinity of the teeth 10, 20, the shafts 11, 21 of the grinding rolls 1, 2 are polygonal, which ensures a good engagement of the teeth 10, 20 in the form of disk portion with the shaft, these shafts 11, 21 are rotatably attached to the frame 3 of the roll mill and are subject to

  directly to the action of the hydraulic motors 12, 22.

  The pumps 14, 24 on their side are actuated through a transmission 4 by the diesel engine 5. The latter can also be replaced by pressurized oil through the lines 13, 23 by means of pumps 14, 24. by

another engine.

  In the pipes 13, 23 and on the pumps 12, 22, and / or on the hydraulic motors 11, 21, there are provided pressure control members, which are indicated here only by a box 6. These control members pressure pressure relief valve, which limits the pressure absolutely and thus prevents overloading. There is also a pressure switch which stops the drive if the maximum working pressure of the oil is reached. But this maximum pressure will preferably be maintained for a few seconds at a standstill, so that a post-action can still break the jammed pieces. After this waiting period determined by a delay means, and only after, will be triggered the inversion of the cylinders by the activated reversing member. This inversion lasts, according to a means of delay, the space of quiques seconds, after

  what the forward motion of the cylinders is automatically restored.

  Since the hydraulic motors act directly on the grinding rollers, the mass to be stopped is practically zero, the rolls being stopped by the jammed pieces, while the control of the oil pressure by the control member ensures an instantaneous interruption of coaching. Diesel engine and pumps can continue

  to turn or can be stopped; but their mass no longer acts.

  5.- In order to avoid clogging of the roll mill, only upper cleaning combs 7 were provided (FIG. 3), Stil produced a plugging despite the discharge hopper 9 having the structure of a movement conveyor oscillatory cleaning is easy through the

lateral openings 8.

  A treadmill 90 carries the crushed material.

Claims (10)

  1.- Roller mill, in particular for clay rock, with two milling rolls individually operable by motor, in opposite directions, and having milling teeth, mill characterized in that each   cylinder (1, 2) is equipped with a reverse hydrostatic control   sible (12, 13, 14; 22, 23, 24) with members for limiting the driving force by limiting the pressure of the engine liquid and the automatic members to automatically reverse the direction of rotation of the cylinders and to restore the rotation   previous period, after the lapse of a predetermined period of   completed. 2. Roll mill according to claim 1, characterized in that each hydrostatic control (12, 13,   14; 22, 23, 24) acts directly on a cylinder (1, 2).   3.- Roll mill according to one of the   1 or 2, characterized in that the grinding teeth (10, 20) have a sawtooth configuration and comprise, between their steep leading edge (101, 201) and their inclined rear edge. (102, 202), a vertex edge (103, 203)   whose gait is at least approximately circumferential.   4.- Roll mill according to any one   Claims 1 to 3, characterized in that the teeth of   grinding (10, 20) have a steep cutting edge (101, 201)   having the structure of a wedge-shaped blade.   5.- Roll mill according to any one of   Claims 1 to 4, characterized in that it does not include   than upper cleaning combs (7).   6. Roll mill according to claim 5, characterized in that it comprises upper cleaning holes (8), lateral, opening under the combs of cleaning (7).   7.- Roll mill according to any one of   Claims 1 to 6, characterized in that it comprises a   discharge hopper (9) which is designed as a conveyor to oscillatory movements.   8.- Roll mill according to any one of   Claims 1 to 7, characterized in that its members   motor pressure reversing and limiting device (6) includes a timing system, in order to maintain a pressure 7.-   motor during a rest period, before starting expensive an inverted movement.   9. A method for operating a roll mill according to claim 1, characterized in that, in the case where a maximum engine fluid pressure is reached.   of at least one of the cylinder controls, the drive   cylinder is stopped, and an inverted movement of the   cylinder is triggered automatically during a pre-   determined, and then, the advancement of the cylinder is restored automatically.   10. A method according to claim 9, characterized in that, before triggering the inverted movement, the maximum driving pressure of the cylinder is maintained during a predetermined period.