Abstract:
A grinding mill comprises a suction device, a separator, a grinding device, and a driving device. The grinding device has a grinding ring, a grinding wheel, mounted on an excentric disc, a strong elastic plate assembly and several adjusting elements allowing to adjust a distance and a mutual orientation between the grinding wheel and the grinding ring as well as a grinding force. The elastic plate assembly attenuates excess grinding forces and thus prevents damaging of the grinding device. The separator has two support rings and a plurality of blades to separate ground micro-sized particles.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a grinding mill, particularly to a grinding mill having a regulating device precisely controlling distance and relative orientation between inner grinding wheels and an outer grinding ring for a better grinding effect, further having a strong elastic plate assembly for attenuating large pressure to prevent damaging of the grinding wheels and ring, furthermore having a separator with several blades mounted on support rings allowing grinded particles to be let out and collected.  
       DESCRIPTION OF RELATED ART  
       [0002]     With increasing quality of life, demands on industrial products have become stricter. In particular, food and medical production has become subjected to environmental standards. The GMP standard regulates grinding mills as to ingredients, iron contents (resulting from wear), noise, temperature, and pollution. So far, few grinding mills of those produced in all countries fulfill the GMP standard.  
         [0003]     Conventionally, grinding mills are designed according to the following criteria: (1) torque, (2) centrifugal force, (3) grinding force, (4) heat, and (5) noise. These criteria are interconnected. When driving a grinding mill by a motor and a shaft, torque results, and grinding stones are by a centrifugal force driven outward, providing a grinding force for grinding. At the same time, heat and noise are generated as adverse effects not to be ignored. In former designs of grinding mills, like in the Raymond Ring-Roll Mill, rotational speed and thus torque and grinding force were fixed. If the grinding force of such a conventional grinding mill turns out to be insufficient or production is to be increased, there is no choice but to replace the motor to provide higher torque. However, arbitrary increasing of motor power leads to higher pressure causing increased wear of grinding stones and mechanical parts as well as to heat and noise generation If pressure becomes too high, the crystal structure of the grinding material is rearranged, inhibiting more effective grinding.  
         [0004]     Conventional grinding mills have already undergone improvements regarding ground material, yet do not fulfill the strict GMP standard.  
         [0005]     In U.S. Pat. No. 5,238,196 “Upright lever pressure type mill”, the present inventor has disclosed a grinding mill which has inner grinding stones pushed against an outer grinding stone by an elastic force and a lever force, minimizing collisions and wear. However, this design still has the following shortcomings:  
         [0006]     1. During the grinding process, strong vibrations are attenuated by springs. After prolonged operation, however, material fatigue readily causes breaking of the springs. When hard materials, such as minerals, ceramics, zirconium oxide, titanium alloy and metal oxides, are ground, the grinding force is not sufficient and the grinding stones are displaced from parallel orientations, hampering the grinding effect thereof. Furthermore, if the elastic force of the spring is insufficient, vibrations are not attenuated and damage as well as excessive metal content and pollution of grinded products result.  
         [0007]     2. In order to take on large grinding forces, large springs with high elastic forces have to be employed, requiring a large space. On the other hand, space is limited, and a pressure system cannot be accommodated. Furthermore, too complicated structural parts and too many dead angles make cleaning difficult.  
         [0008]     For appropriate operation, parallel orientations of inner and outer grinding stones are important. During the grinding process, the inner and outer grinding stones easily collide due to pressure and friction. If the grinding force is sufficiently large, the inner and outer grinding stones do not need to touch each other, allowing for effective grinding.  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to provide a grinding mill having inner and outer grinding stones the distance of which is regulated and which are kept parallel to each other and where excessive pressure is attenuated.  
         [0010]     Another object of the present invention is to provide a grinding mill which is capable of bearing high pressure and attenuating vibrations and which allows to let out and collect grinded products.  
         [0011]     The present invention can be more fully understood by reference to the following description and accompanying drawings. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]     As shown in  FIGS. 1-3 , the grinding mill of the present invention mainly comprises: a main body  10 , accommodating structural parts for grinding; a suction assembly  20 , connected with a collecting apparatus  71  for collecting grinded products; a separator  30 , separating ground products according to sizes thereof; a grinding device  40 ; several regulating devices  50 ; and a driving device  60 .  
         [0013]     The suction assembly  20  is placed on an upper end of the main body  10 . The separator  30 , the grinding device  40  and the regulating devices  50  are housed inside the main body  10 . A feeding hole  11  connected to a feeding apparatus  70  is cut into the main body  10 , providing raw material to be ground. The main body  10  further has a lower end with a resupplying chamber  12 . The resupplying chamber  12  has a resupplying hole  121  which via a resupplying tube  72  takes in excess air from the collecting apparatus  71 , which is subsequently led back into the main body  10 . A draining chamber  13  is placed at the lower end of the main body  10 . A draining tube  131  leads from the draining chamber  13  to a waste chamber  14  where non-grindable components and waste from the grinding process are collected.  
         [0014]     The suction assembly  20  has an upper end with a motor bearing, a lower end which is connected with the upper end of the main body  10  and an inner space which accommodates a high-speed separator motor  22  and a separator shaft  21  that vertically reaches downwards. A frequency controller controls a centrifugal force of a separator movement around the separator shaft  21  that is needed for appropriate separation. The separator  30  has a drum body  35 ,  35   a ,  35   b ,  35   c , allowing precisely to regulate a degree of coarseness of separated particles. A suction tube  23  leads laterally away from the suction assembly  20  into a fan apparatus  73 , so that particles separated by the separator  30  are sucked out of the main body  10 .  
         [0015]     Referring to  FIGS. 1-4 , the separator  30  is fixed on the separator shaft  21  within the main body  10  and comprises two support rings  31  and a plurality of blades  32 . The two support rings  31  are symmetrically disposed on upper and lower sides of the separator  30 . Arc-shaped openings  311  and are cut in each of the two support rings  31 . Fixing holes  312  surround the sectorial openings  311  on each of the two support rings  31 . The blades  32  are radially oriented and respectively fixed by vertical rods  321  in the fixing holes  312 . The openings  311  let small particles pass, while larger particles are driven out between the blades  32  by the centrifugal force of the separator movement to fall down into the grinding system  40  and to be ground further.  
         [0016]     Referring to  FIGS. 2-5 , the separator  30  has a guiding assembly  340  placed in an upper part of the main body  10 . The drum body  35  is placed above a circular pan  34 , with a gap C 1  remaining in between. The pan  34  is fixed on the separator shaft  21  at an adjustable vertical position. Thus an air flow and a radius of vortices is controlled. For example, for grinding small particles the gap C 1  is adjusted to a small value, like C 2  in  FIG. 4B . The drum body has a peripheral surface into which openings  351  are cut. The openings  351  are partly covered by inclined lids  352 , so as to form an air flow that carries particles along with the centrifugal force. Thus the separator  30  works like a sieve, so that larger particles are brought outward to fall down along inner walls of the main body  10  and to be reinserted into the grinding process. Smaller particles stay in an inner air flow and rise along the separator shaft  21 . Thus an air flow is controlled that leads larger particles outward to be further grinded, allowing for repeated grinding down to micro-sizes. Larger particles are led out by the centrifugal force of the rotational movement at high speed, so that effective sieving of particles down to micro-sizes is attained.  
         [0017]     Referring again to  FIGS. 3-5   a , in an embodiment of the present invention, a drum body  35   a  is used having an upper edge with an extension ring  34   a  that is vertically adjustable, providing additional space for separating larger particles through the blades  32 .  
         [0018]     Referring to  FIG. 5   b , in another embodiment of the present invention, a drum body  35   b  is used having lids  353  that are inclined inwards. As shown in  FIG. 5   c , in a further embodiment of the present invention, a drum body  35   c  is used having lids  354 ,  355  that are alternatingly inclined inwards and outwards for adjusting to the air flow carrying particles.  
         [0019]     Referring now to  FIGS. 6-9  and  13 , the grinding device  40  is placed inside the main body  10 , surrounded by a grinding ring  15 . The grinding device  40  has a main axis  41  which is driven by the driving device  60  to perform a rotational grinding movement. An excentric disc  42  is set on the main axis  41 , carrying a plurality of grinding wheels  43  arranged to have suitable distances to the grinding ring  15 . Ramps  421 , each placed next to one of the grinding wheels  43  on the excentric disc  42 , guide raw material into two vertical sections between the grinding wheels  43  and the grinding ring  15 , preventing accumulation thereof. Furthermore, air inlets  422  are placed on the excentric disc  42 , covered by hinged lids  423 . The lids  423  freely open in the airflow that is driven by the fan apparatus  73 .  
         [0020]     The driving device  60  has a main motor  61  which drives the grinding device  40 . The main motor  61  extends into a casing  62 , driving the grinding movement of the main axis  41 . A gearbox is accommodated by the casing  62 , allowing for high, middle and low speeds of the grinding movement according to raw material for optimum throughput.  
         [0021]     For operating the grinding mill of the present invention, first the separator motor  22 , then the main motor  61  are turned on. Consequently, the main axis  41  and the excentric disc  42  perform the grinding movement, causing the grinding wheels  43  to revolve inside of the grinding ring  15 , performing the grinding process.  
         [0022]     After switching on the fan apparatus  73 , air enters the main body  10  through resupplying tube  72 , the resupplying hole  121  and the air inlets  422 . At the same time, raw material enters the main body  10  through the feeding hole  11 . Entering raw material is not carried away by air flow due to large particle sizes and rather falls directly on the excentric disc  42  within the grinding ring  15 . The rotating grinding movement of the excentric disc  42  causes raw material to be led along the ramps  421  on two vertical sections between the grinding wheels  43  and the grinding ring  15  and to be ground. Ground material rises with the air flow, entering the separator  30 , and is separated there, with smaller particles being carried away to the suction tube  23  and larger particles falling back into the main body  10 . Outflowing air is recycled back through the resupplying hole  121  and the air inlet  422 , preventing raw material from accumulating.  
         [0023]     Referring to  FIGS. 6-12 , each of the regulating device  50  of the present invention is attached to one of the grinding wheels  43 , comprising a base  432  with a through hole  431  and an elastic plate assembly  433  extending downward from the base  432  and made of alloyed steel (like a spring used in trucks) and having a far end with a longitudinally oriented elongated incision  434 . The elastic plate assembly  433  has a predetermined deformation characteristic and is made of a single plate or a plurality of plates.  
         [0024]     The excentric disc  42  has a periphery into which several incisions  441  are cut for accommodating seats  44  of the grinding wheels  43 , into which one of the bases  432  of the grinding wheels  43  is put. Each of the seats  44  has a lower side from which an extension piece  442  extends downward. The extension piece  442  has a lower end into which a threaded hole  446  is cut and an outer side along which the elastic plate assembly  433  of one of the regulating devices  50  runs. Each of the seats  44  has an outer side which is partly covered by a covering plate  443  and two lateral sides into each of which a horizontal elongated hole  444  is cut. For each of the seats  44 , a first adjusting element  45  is put through the elongated holes  444  and the through hole  431  of one of the regulating devices  50  and secured by nuts. If desired, a protecting ring is added to obtain an increased fastening area. The covering plate  443  has a threaded hole  447  in a central position through which a second adjusting element  46 , for example a screw, is put to press against the elastic plate assembly  433 . A third adjusting element  47 , for example a screw, passes through the elastic plate assembly  433  at the far end thereof and is screwed into the threaded hole  446 , positioning the elastic plate assembly  433 . Thus a grinding force of each of the grinding wheels  43  is adjusted.  
         [0025]     For each of the grinding wheels  43 , the first adjusting element  45  provides for positioning thereof, the second adjusting element  46  adjusts a distance thereof to the grinding ring  15  and maintains a parallel orientation thereof with respect to the grinding ring  15 . The distances between the grinding wheels  43  and the grinding ring  15  and the mutual orientations thereof are important for effective grinding. Preventing the grinding wheels  43  and the grinding ring  15  from touching each other, with only ground material placed in between, ensures optimum grinding. For each of the grinding wheels  43 , the first adjusting element  45  is adjusted by gliding in the elongated holes  444 , taking along the corresponding grinding wheel  43 . The second adjusting element  46  presses against the base  432  of the grinding wheel  43 , allowing to regulate the distance thereof to the grinding ring  15  and to ensure parallel orientation thereof with respect to the grinding ring  15 . The elastic force of the elastic plate assembly  433 , pulls the grinding wheel  43  outward, towards the grinding ring  15 , at the same time attenuating any excessive grinding force to prevent damaging of the grinding wheels  43 .  
         [0026]     The extension piece  442  of each of the seats  44  at the lower end thereof has a sweeping plate  445 , which during the rotating grinding movement sweeps non-grindable material and waste in the draining chamber  13  into the draining tube  131  to fall into the waste chamber  14 .  
         [0027]     As the above explanation shows, the grinding mill of the present invention offers the advantages of (1) adjustability of distances between the grinding wheels and the grinding ring and the mutual orientations thereof, (2) attenuating of excessive grinding force, and (3) the capability of separating and collecting tiny particles.  
         [0028]     While the invention has been described with reference to preferred embodiments thereof, it is to be understood that modifications or variations may be easily made without departing from the spirit of this invention which is defined by the appended claims.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]      FIG. 1  is a partial sectional view of the grinding mill of the present invention.  
         [0030]      FIG. 2  is a partial sectional view of the grinding mill of the present invention with the separator assembled.  
         [0031]      FIG. 3  is a partial sectional view of the grinding mill of the present invention with the separator assembled in another embodiment.  
         [0032]      FIGS. 4-4B  are views of the separator of the present invention, showing relative positions of structural parts.  
         [0033]      FIGS. 5-5   c  are perspective views of the drum body of the present invention in various embodiments.  
         [0034]      FIG. 6  is a perspective view of the separator and the grinding device of the present invention.  
         [0035]      FIG. 7  is a perspective view of the excentric disc of the present invention.  
         [0036]      FIG. 8  is a perspective view of the excentric disc of the present invention with the grinding wheels mounted.  
         [0037]      FIG. 9  is a perspective view of the grinding device of the present invention.  
         [0038]      FIG. 10  is a perspective view of one of the grinding wheels of the present invention.  
         [0039]      FIG. 11  is a sectional view of one of the grinding wheels and regulating devices and the grinding ring of the present invention.  
         [0040]      FIG. 12  is a side view from outside of one of the grinding wheels and regulating devices of the present invention.  
         [0041]      FIG. 13  is a schematic illustration of the grinding mill of the present invention in conjunction with a feeding apparatus, a collecting apparatus and a fan apparatus.