Abstract:
A station for supporting a moving conveyor belt ( 3 ) includes a cradle ( 17 ) for guiding the belt ( 3 ), the cradle ( 17 ) having at least two rollers ( 33 ) for guiding and supporting the belt ( 3 ), a frame ( 15 ) for supporting the rollers ( 33 ), and anti-jamming protection ( 35 ) disposed along the rollers ( 33 ) and secured to the frame ( 15 ). Protection ( 35 ) includes a protective bar ( 36 ) extending continuously along the length of at least two rollers ( 33 ), being substantially parallel to a generator line of each roller ( 33 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a station for supporting a conveyor having a movable belt, the station being of the type comprising: 
     a cradle for guiding the belt, the cradle comprising at least two rollers for guiding and supporting the belt; 
     a frame for supporting the rollers; and 
     anti-jamming protection disposed along the rollers and secured to the frame. 
     2. Field of the Invention 
     In order to handle bulk materials, it is known to use conveyors belts, also known as conveyors. Such a conveyor essentially comprises a belt forming a loop and supported by support stations. The belt is held at its end by two reversing rollers. One of the rollers is motor-driven in order to drive the belt. 
     Such a support station is generally constituted by a frame together with a belt support cradle. The cradle generally comprises rollers or sliding skids. 
     With rollers, they rotate as the belt advances and thus presents a risk for an operator on the side of each station that is upstream relative to the advance direction of the belt. The movement of the rollers can entrain a garment and jam it in the angle between the roller and the belt. This angle is commonly referred to as the “reentrant” angle. An operator can also inadvertently have a hand trapped in the reentrant angle while performing a maintenance operation. 
     Anti-jamming protection devices exist for conveyor stations. Each type of conveyor requires a special type of protection device, some of which are relatively expensive. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a protection device that is simple and of moderate expense. 
     To this end, the invention provides a station of the above-specified type characterized in that the protection comprises a protective bar extending continuously along the length of at least two rollers extending substantially parallel to a generator line of each roller. 
     According to other characteristics of the invention:
         the bar is bent and matches the curvature of the guide cradle;   the bar comprises an elongate core and a sheath surrounding the elongate core;   the bar presents a cross-section having a side facing towards the belt and a first circularly-arcuate concave side adjacent thereto having substantially the same diameter as the rollers, with the circularly-arcuate side being situated facing each of the rollers;   the cross-section of the bar includes a second circularly-arcuate side, adjacent to the side facing towards the belt;   the rollers and the bar are spaced apart by non-zero spacing; and   the protection includes fastener means for fastening to the frame, the fastener means comprising two end plates together with fastener screws, the bar having an end face at each of its ends, the end plates being secured to the bar via each of the end faces of the bar by the fastener screws, and also being fastened to each of the sides of the frame.       

     The invention also provides a conveyor, characterized in that it comprises a set of support stations as described above with a transport belt suitable for traveling over the stations, the belt and the bar at each station being spaced apart by non-zero spacing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       The invention can be better understood on reading the following description given purely by way of example and made with reference to the accompanying drawings, in which: 
         FIG. 1  is a diagrammatic side view of a conveyor belt supported by roller stations; 
         FIG. 2  is an end view of a station in section on plane II-II of  FIG. 2 ; 
         FIG. 3  is a corresponding side view seen looking along arrow III of  FIG. 2 ; 
         FIG. 4  is a side view similar to  FIG. 3 , showing a variant embodiment of the means to secure the anti-jamming protection to the frame; and 
         FIG. 5  is a front view corresponding to  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The conveyor  1  shown in  FIG. 1  is intended, for example, for transporting minerals taken from a quarry. It comprises a conveyor belt  3  forming a loop and engaged at its ends around two reversing rollers  5  and  7 . Of those two rollers, one roller  5  is motor driven for driving the belt  3 , thereby defining the upstream end of the belt  3 . The loop is thus made up of a top segment  8  for transporting minerals, and a return bottom segment  8 ′. 
     Along the length of the top segment  8 , the belt  3  is supported by a plurality of stations  9  that serve to support and guide the belt  3 . The stations  9  are all identical. 
     As shown in  FIG. 2 , each station  9  comprises a metal carrier frame  15  and a cradle  17  for supporting and guiding the belt  3 . The frame  15  essentially comprises top and bottom transverse beams  21  and  22 , and two legs  23  standing on the ground  25  on either side of the belt  3 . The transverse beams  21  and  22  interconnect the two legs  23 . The frame  15  is placed directly on the ground  25  via the bottom beam  22 . 
     The top and bottom beams  21  and  22  are vertically spaced apart with the bottom segment  8 ′ of the belt  3  passing between the two beams. 
     The frame  15  has two roller-support lugs  29 . The lugs  29  are constituted by metal blades having their ends secured to the top transverse beam  21  of the frame  15 . Each lug  29  forms a right-angled triangle. A horizontal bottom center roller  31  and two sloping side rollers  33  are mounted to move in rotation between the support lugs  29  and the legs  23  of the frame  15 . These rollers  31  and  33  extend in a common vertical plane and are suitable for receiving the belt  3  and for deforming it to take up a trough shape. 
     On the upstream side of the support station  9 , an anti-jamming protection  35  (visible in  FIG. 3 ) masks the so-called “reentrant” angle formed by the belt  3  and the two support rollers  31  and  33 . The protection  35  essentially comprises a bar  36  and fastener plates  37 . The bar  36  comprises a tubular metal core  38  and a sheath  39  sheathing the core  38 . By way of example, the sheath  39  is made of polyethylene. The section  41  of the sheath  39  is pierced by an orifice  43  for receiving the tubular core  38 . The section  41  of the sheath  39  has a straight side  45  and a side  47  adjacent to the side  45  that is circularly arcuate, having the same diameter as the rollers  31  and  33 . These two sides  45  and  47  form an angle that matches the angle formed between the belt  3  and the rollers  31  and  33 . 
     The section  41  of the sheath  39  has a second circularly-arcuate side  48  of diameter greater than the diameter of the side  47 , and suitable for protecting a roller. The side  48  is likewise adjacent to the straight side  45 . 
     The protection  35  is secured to the frame  15  of the station  9  on either side of the belt  3  by the fastener plates  37  that are of greater diameter. 
     The fastener plates  37  are secured by fastener screws  53  to the two end faces of the bar  36 , and they are also fastened to the frame  15 , e.g. by welding. 
     The bar  36  that extends continuously from one end of the cradle  17  to the other while being held solely at its ends. 
     The protection  35  is situated beneath the belt  3  facing the rollers  31  and  33  and spaced apart a little from the belt  3  and the rollers  31  and  33 . The space e formed between the protection  35  and the belt  3  advantageously lies in the range 0 to 10 millimeters (mm), being about 5 mm, for example. The space e′, formed between the protection  35  and the rollers  31  and  33  is substantially equal to  e . 
     As shown in  FIG. 2 , the protection  35  masks the angle between the rollers  31  and  33  and the belt  3  over the entire length of the cradle  17 , via its sides  45  and  47 , and following the curvature of the cradle  17  in the width direction of the belt  3 . 
     The sheath  39  and the tubular core  38  are thus folded together essentially in two zones that correspond to the angles formed by the axes of each of the side rollers  33  relative to the axis of the central roller  31 . 
     A station  9  of a conveyor  1  with such protection  35  is made very easily by having the bar  36  that is easy to fabricate and to mount. 
     The sheath  39  is fabricated by the following method: extruding a plastics material, e.g. polyethylene, through a die. After being cut to length, a continuous part is obtained that is of constant section. The section, defined by the shape of the die, presents a straight side  45  and two circularly-arcuate sides  47  and  48  of different diameters and each adjacent to the straight side  45 . A circular hole in the section of the sheath is provided for forming a continuous tubular orifice  43  in the bar  36  while it is being extruded. 
     Thereafter, a metal tube of diameter matching that of the hole is inserted into the orifice  43 , with the tube forming the core  38  of the bar  36 . 
     The bar  36  as formed in this way is then bent to match the shape of the cradle  17  of the conveyor  1 , and is finally secured at its ends to the frame  15  of a station  9 . 
     The relative deformability of the core  38  and of the sheath  39  makes it possible to use a single original bar  36  for fabricating a protective device  35  on conveyors  1  of different curvatures. 
     Preferably, the section of the bar  39  presents two circularly-arcuate sides  45  and  48  having different diameters that correspond to two different diameters of standard rollers  31 ,  33 , thus enabling the bar to be matched to different types of conveyor  1 . 
     In a variant embodiment shown in  FIGS. 4 and 5 , the fastener plate  37  at each end of the bar  26  and the fastener screws  53  are replaced by a folded metal sheet  60 , a backing sheet  62 , and a pin  64 . 
     The folded sheets  60  are pressed against the outside faces of the legs  23 . 
     The backing plates  62  are placed against the inside faces of the legs  23  and are securely fastened to the folded sheets  60  by bolts  66  such that the legs  23  are sandwiched between the sheets  60  and the backing plates  62 . 
     Each of the sheets  60  has a top edge  68  folded outwards, with a notch  70  being cut therein of a shape that matches that of the bar  36 . 
     The bar  36  is received and supported at its two ends in the notches  70  of the folded sheets. It is held at its ends in the notches by the U-shaped pins  64  engaged in through holes  72  formed in the bar  36  and slidably engaged under the folded edges  68 .