Abstract:
An apparatus for comminuting rocks, comprising a frame having a restrictive passageway with an inlet and an outlet end for relative displacement of rocks from the inlet to the outlet end. A rotary impacting device is secured to the frame in the passageway so as to be journaled with respect to the frame. The rotary impacting device has hammer elements on an outer periphery of the device. The hammer elements are adapted to scoop and impact rocks in the passageway to project the rocks toward the outlet of the apparatus. An actuator is mounted to the frame and operationally connected to the rotary impacting device for imparting a rotation of the rotary impacting device. A screen is adapted to comminute upon impact the rocks propelled thereon by the rotary impacting device. The screen is positioned at the outlet end such that comminuted rocks exiting from the apparatus are below a predetermined size.

Description:
TECHNICAL FIELD  
         [0001]    The present invention generally relates to equipment for comminuting or crushing rocks into finer particles.  
         BACKGROUND ART  
         [0002]    There exists a plurality of rock-crushing apparatuses and methods for comminuting rocks into finer particles, such as gravel. Gravel is typically used for landscaping, and many other construction applications, etc. There are numerous uses for crushed stone. For instance, rock-crushing apparatuses are typically used to transform an uneven terrain into a practical road or path. More recently, the recreational industry has created a need for bicycle paths of gravel.  
           [0003]    U.S. Pat. No. 3,701,485, issued on Oct. 31, 1972 to Kimble, discloses a “Rotor Construction for Impact Crusher.” U.S. Pat. No. 4,373,678, issued to Reitter on Feb. 15, 1983, is entitled “Rotary Impact Crusher Having a Continuous Rotary Circumference.” Both these patents describe impact crushers that include a rotary element that entrains rocks into a throat portion wherein rocks are crushed into finer particles. The crushing is caused by a combination of the action of the rotary element on the rocks caught in the throat portion, and impact between the rocks.  
           [0004]    In designing rock-crushing apparatuses, a few factors are of importance. The performance of a rock crusher, i.e., the quantity of rock crushed with respect to time (e.g., tons/hour), is a primary feature in the rating of a rock-crushing apparatus. In the existing rock-crushing apparatuses, the rotary element is directly involved in the crushing of rocks by exerting a squeezing pressure on the rocks in the throat portion of the machine, whereby the rotary speed is directly related to the rate of production of the rock-crushing apparatuses.  
           [0005]    It is also important that the rock-crushing apparatuses give consistent results. For instance, rock-crushing apparatuses are typically rated in accordance with the anticipated dimensions of the rock crushed by the apparatus. For instance, a rock-crushing apparatus can be rated as a zero- to two-inch crusher, in which case rock sizes go from minute particles to two inches at the exit of the apparatus. It is pointed out that the finer the range, the slower the speed of operation.  
           [0006]    Another important factor is the durability of the rock-crushing apparatuses. Rock-crushing apparatuses undergo substantial wear of operating pieces. It is possible to increase the productivity of a rock-crushing apparatus if it is durable. Moreover, low maintenance and few repairs help in decreasing the costs related to operation of rock-crushing apparatuses.  
           [0007]    These factors have a negative effect on each other. For instance, an increase in speed of the rotary element will most likely have an effect on the durability of the equipment. Moreover, the increased speed can damage the rotary element such that output of the rock-crushing apparatus becomes inconsistent. It would thus be desirable to have a rock-crushing apparatus that optimizes these factors.  
         SUMMARY OF INVENTION  
         [0008]    It is a feature of the present invention to provide a novel apparatus for comminuting rocks.  
           [0009]    It is a further feature of the present invention to provide a novel method for comminuting rocks.  
           [0010]    It is a still further feature of the present invention to optimize a performance of rock-crushing apparatuses.  
           [0011]    According to the above features, and from a broad aspect, the present invention provides an apparatus for comminuting rocks, comprising a frame having a restrictive passageway with an inlet and an outlet end for relative displacement of rocks from the inlet to the outlet end; a rotary impacting device secured to the frame in the passageway so as to be journaled with respect to the frame, the rotary impacting device having at least one hammer element on an outer periphery of the device, the at least one hammer element adapted to scoop and impact rocks in the passageway to project the rocks toward the outlet of the apparatus; actuation means mounted to the frame and operationally connected to the rotary impacting device for imparting a rotation of the rotary impacting device; and screening means adapted to comminute upon impact at least some of the rocks propelled thereon by the rotary impacting device, the screening means being positioned in the outlet end such that comminuted rocks exiting from the outlet end are below a predetermined size.  
           [0012]    According to a further feature of the present invention, there is provided a method of use of a hammer element of an apparatus for comminuting rocks, comprising the steps of: i) providing a hammer element having a leading impacting surface and a substantially identical trailing impacting surface opposed thereto, and a connector portion for securing the hammer element to a rotor of an apparatus for comminuting rocks, the impacting surfaces protruding from the rotor; ii) mounting the hammer element to the rotor with a direction of rotation of the rotor being generally normal to the leading impacting surface; iii) impacting rocks with the leading impacting surface of the hammer element by actuating the rotor in rotation, thereby sharpening an edge of the trailing impacting surface; iv) reversing the hammer element such that the direction of rotation of the rotor is generally normal to the trailing impacting surface; and v) repeating step iii) such that the trailing impacting surface impacts rocks. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0013]    A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:  
         [0014]    [0014]FIG. 1 is a side elevational view, partly cross-sectioned, of an apparatus for crushing rocks constructed in accordance with the present invention;  
         [0015]    [0015]FIG. 2 is a perspective view of a screen of the apparatus for crushing rocks;  
         [0016]    [0016]FIG. 3 is a perspective view of a hammer element constructed in accordance with the present invention;  
         [0017]    [0017]FIG. 4 is a top plan view of the hammer element of FIG. 4;  
         [0018]    [0018]FIG. 5 is a cross-sectional view of the hammer element as secured to a rotor of the present invention;  
         [0019]    [0019]FIG. 6A is a side elevational view of the hammer element subjected to wear; and  
         [0020]    [0020]FIG. 6B is a side elevational view of the hammer element of FIG. 6A being further subjected to wear. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]    Referring to the drawings, and more particularly to FIG. 1, an apparatus for comminuting rocks constructed in accordance with the present invention is generally shown at  10 , and will hereinafter be referred to as the apparatus  10 . The major constituent parts of the apparatus  10  are a frame  12 , a rotary impacting device  14 , an actuating group  16  and a screen  18 .  
         [0022]    Still referring to FIG. 1, the frame  12  is shown defining an inlet  20  at a front end thereof, and an outlet  22  at a rear end thereof. The frame  12  includes the casing generally shown at  24 , enclosing the actuation group  16  and defining a passageway  26  between the inlet  20  and the outlet  22 .  
         [0023]    Still referring to FIG. 1, the rotary impacting device  14  is supported by the frame  12  in the passageway  26 . The rotary impacting device  14  is driven by a drive train connected to the actuation group  16 , and has an axis  40  about which it rotates in the direction illustrated by arrow  42 . Accordingly, the rotary impacting device  14  is supported by bearings on opposed ends thereof. More precisely, the rotary impacting device  14  is positioned adjacent to the screen  18  and the outlet  22 . The passageway  26  defines a direction going from the inlet  20  to the outlet  22 , and the axis  40  is generally perpendicular to this direction.  
         [0024]    The rotary impacting device  14  is actuated by the actuation group  16 . Actuation from the actuation group  16  is transmitted to the rotary impacting device  14  by the drive train, such as a belt/chain-and-pulley assembly, intermeshing gears or the like. It is pointed out that the bearings and the transmission members must be protected by casing elements of the frame  12  to prevent infiltration by the rocks/dirt particles. This will ensure a longer life of these constituents.  
         [0025]    The rotary impacting device  14  has hammer elements  44  removably secured thereto. Referring to FIGS. 3, 4 and  5 , one of the hammer elements  44  is shown in detail. Referring to FIG. 5, the hammer element  44  has a pair of impacting surfaces  46 . Connector bores  48  are provided on a connector portion  49  of the hammer element  44  for securing the hammer elements to a rotor portion  50  of the rotary impacting device  14 . Preferably, the connector portion  49  is inserted into a corresponding groove of the rotor portion  50 , such that only the impacting surfaces  46  protrude radially from the rotor portion  50 . When the hammer elements  44  are positioned on the rotor portion  50 , axes of the connector bores  48  extend radially from a center of the rotor portion  50 , i.e., the axis  40 . As shown in FIG. 5, the impacting surfaces  46  create concavities  52  with the rotor portion  50  so as to capture rocks therein. The connector bores  48  are tapped, and receive a connector member, e.g., a bolt, from an interior of the rotor portion  50 .  
         [0026]    Referring to FIG. 2, the screen  18  is shown having a support structure  80  supporting in spaced-apart relation a plurality of ribs  82 . The spacing between the ribs  82  is directly related to the output-size specification of the rocks. The screen  18  is positioned in the passageway  26  so as to completely block the outlet  22 . Accordingly, rocks will have to go through the ribs  82  to exit the apparatus  10  through the outlet  22 . This ensures that the components exiting from the apparatus  10  will only be below a specified size determined by the spacing between the ribs  82 .  
         [0027]    The screen  18  is configured so as to be readily removable from the frame  12 . For instance, size ratings may change in the course of a day, whereby the apparatus  10  must be adapted to produce consistent output with regard to size. Therefore, a plurality of screens  18  with different size ratings can be provided with the apparatus  10 .  
         [0028]    Moreover, the ribs  82  must be individually removable from the support structure  80 . This is necessary when, for instance, one of the ribs  82  is damaged and must be replaced. It is also possible to remove some of the ribs  82  to change the size rating of the screen  18 .  
         [0029]    The apparatus  10  is provided in a displaceable configuration or in a stationary configuration. In the displaceable configuration, the frame  12  rests on lateral walls on the ground at  90  (FIG. 1), and these lateral walls define the passageway  26  therebetween. Bottom surfaces of the lateral walls are adapted for sliding on the ground when pushed in the direction illustrated by arrow  92  by a vehicle connected to the rear end of the apparatus  10 . It is obvious that a vehicle may be attached to a front end of the apparatus  10  to pull the latter in the direction shown by arrow  92 .  
         [0030]    Still referring to FIG. 1, relative motion is shown between the apparatus  10  and rocks and dirt illustrated at A. Accordingly, rocks and dirt are fed to the rotary impacting device  14 , which is actuated in rotation throughout operation of the apparatus  10 . Accumulation is created at the rotary impaction device  14 , and same entrains rocks and dirt of the accumulation in the concavities  52  (FIG. 5).  
         [0031]    The speed of the rotary impacting device  14  causes the rocks and dirt entrained thereby to be propelled against the ribs  82  of the screen  18 . The impact will cause the comminution of the rocks, and the momentum of these comminuted rocks will lead them through the outlet  22  out of the passageway  26 . Rocks that are either still too large to pass through the gaps between the ribs  82  or that bounce back into the passageway  26  are guided back to the accumulation by guiding portion  84  at the bottom of the screen  18 . The guiding portion  84  thus acts as a guiding portion. Once reaching the accumulation, the rocks will be entrained by the rotary impacting device  14 .  
         [0032]    The guiding portion  84  will perform an entrainment action against rocks above a predetermined size in the case of the displaceable configuration of the apparatus  10 . Namely, a gap is provided between a bottom portion of the guiding portion  84  and the ground G, and the gap is chosen so as to allow rocks below a predetermined size to stay on the ground G. On the other hand, rocks above that predetermined size are entrained by the guiding portion  84 . As shown in FIG. 1, the output will be in the form of gravel B.  
         [0033]    As shown in FIG. 1, a protection screen  28  is provided at the inlet  20  to prevent rocks from being propelled out of the front end of the apparatus  10  due to the direction of rotation of the rotary impacting device  14 . For instance, the protection screen  28  may be a set of chains hanging loosely. The chain links have sufficient inertia to stop the rocks.  
         [0034]    A throat portion  26 ′ is defined in the passageway  26  between hammer elements  44  of the rotary impacting device  14  and a crusher block  30 . Bigger rocks are fragmented into smaller particles by the crushing action created in the throat portion. The crusher block  30  is changeable, and can be chosen according to a desired throat portion size.  
         [0035]    In the stationary configuration of the apparatus  10 , also illustrated in FIG. 1, a bottom panel is provided at  90  so as to define four walls of the passageway  26 . The apparatus  10  is positioned such that the direction of the passageway  26  is not parallel to the ground. As shown in FIG. 1, a coordinate system X′-Y′ is provided for the stationary configuration, with the ground being represented by the X′-axis. Accordingly, The inlet  20  is above the outlet  22 , such that rocks and dirt fed into the inlet  20  will be directed to the rotary impacting device  14  by sliding against the bottom panel at  90 . The feed and the removal of rocks can be performed by a conveyor system (not shown), or by dumpsters unloading their contents at the inlet  20 .  
         [0036]    In the case of the displaceable or mobile apparatus  10 , a portion of the rocks propelled by the rotary impacting device  14  will hit the ground and therefore abrade the top surface of the ground and, for instance, comminute larger rocks that are buried. The level of abrasion can be adjusted by changing the position of the guiding portion  84 . This adjustment will enable control of a depth of abrasion of the ground G. Another way to increase the level of abrasion is by increasing the speed of rotation. Moreover, it is preferred to slow the translation of the apparatus  10 .  
         [0037]    Referring to FIGS. 6A and 6B, it is shown how the use of the hammer elements  44  can be optimized. A direction of rotation of the rotary impacting device  14  is shown at  100 . The wear of the hammer element  44  is shown by dashed line  102 , subsequent to impact with the rocks. Due to the symmetry of the connector portion  49  of the hammer element  44  with respect to a plane normal to axis  104  and to the drawing sheet, the hammer element  44  may be rotated after wear such that one of the impacting surfaces  46 , which was previously trailing, now is the leading element. This impacting surface, illustrated at  46 B, will show a sharp edge that will enable the entrainment of rocks.  
         [0038]    As shown in FIG. 6B, the impacting surface  46 B will eventually lose the sharp edge. However, the wear of the rocks will cause the trailing impacting surface  46 A to be sharpened, whereby the hammer element  44  can be turned over once more. Therefore, the use of the hammer elements  44  is optimized in the present invention.  
         [0039]    It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims.