Abstract:
A method and device for forming groups of products, whereby a substantially continuous input succession of products is fed to an input of an endless conveyor, which has a conveying branch and a return branch extending between the input and an output, and which has a variable speed drive member operated to impart a variable speed to the conveyor at the input, and to generate, along the conveying branch, a succession of equally spaced on-line gaps defining a succession of groups of products; the conveying and return branches are both engaged by a powered compensating device for varying the lengths of the conveying and return branches in complementary manner, so as to maintain a constant speed of the conveyor at the output and compensate for any gaps in the input succession.

Description:
[0001]    The present invention relates to a method of forming groups of products.  
           [0002]    The present invention may be used to particular advantage in the tobacco industry for processing cigars coming off a production machine, to which the following description refers purely by way of example.  
         BACKGROUND OF THE INVENTION  
         [0003]    In the tobacco industry, cigars coming off a production machine are normally collected in containers, from which they are removed manually and divided into groups, each comprising a given number of cigars; and the groups are then placed inside boxes in one or more superimposed layers to form respective boxes of cigars.  
           [0004]    Besides employing considerable labour, the above method is normally time-consuming and expensive, and may result in damage to the cigars.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the present invention to provide a straightforward, low-cost method of dividing a succession of products into a succession of groups, each containing a given number of products, to facilitate boxing of the products.  
           [0006]    According to the present invention, there is provided a method of forming groups of products, as claimed in claim  1  and, preferably, in any one of the following Claims depending directly or indirectly on claim  1 .  
           [0007]    The present invention also relates to a device for forming groups of products.  
           [0008]    According to the present invention, there is provided a device for forming groups of products, as claimed in claim  8  and, preferably, in any one of the following Claims depending directly or indirectly on claim  8 . 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:  
         [0010]    [0010]FIG. 1 shows an operating diagram in perspective of a preferred embodiment of the device according to the present invention;  
         [0011]    [0011]FIG. 2 shows a schematic side view, with parts removed for clarity, of the FIG. 1 device;  
         [0012]    [0012]FIG. 3 shows a larger-scale section of a FIG. 2 detail in two distinct operating positions. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    Number  1  in FIG. 1 indicates as a whole a conveying device for receiving, at an input  6 , a continuous input succession  2  of cigars  3  arranged with their respective longitudinal axes  4  crosswise to their feed direction  5 . Cigars  3  in input succession  2  may obviously be fed to input  6  by a conveyor (not shown), or by a transfer device (not shown) for feeding cigars  3  to input  6  one at a time at a given constant rate.  
         [0014]    Conveying device  1  feeds cigars  3  to an output  8  in a travelling direction  7  also crosswise to longitudinal axes  4 ; compensates for any accidental input gaps  9  in input succession  2 , each caused by a missing cigar  3 ; and divides cigars  3  into groups  10 , each defined, in the example shown, by a succession of five cigars  3 , and each separated from each adjacent group  10  by an on-line gap  11  corresponding to a missing cigar  3 .  
         [0015]    As shown in FIG. 2, conveying device  1  comprises a plate frame  12  in a plane parallel to travelling direction  7  and crosswise to longitudinal axes  4 ; and a conveyor  13  comprising a conveying branch  14  extending in travelling direction  7  from input  6  to output  8 , and a return branch  15  extending from output  8  to input  6 . Conveyor  13  comprises an elongated conveying member defined by two facing endless chains  16  looped about a number of pairs of sprockets meshing with chains  16  and supported for rotation by frame  12 .  
         [0016]    More specifically, said pairs of sprockets comprise a first pair of sprockets  17  fitted to frame  12  to rotate idly about a common axis  18  parallel to longitudinal axes  4  and located at input  6 ; a second pair of sprockets  19  fitted to frame  12  to rotate idly about a common axis  20  parallel to axis  18  and located at an intermediate point along conveying branch  14 ; a third pair of sprockets  21  fitted to frame  12  to rotate idly about a common axis  22  parallel to axis  18  and located at output  8 ; and a fourth pair of sprockets  23 , which are fitted to an output shaft  24  of a “brushless” motor  25  fitted to frame  12 , and rotate with shaft  24  about an axis  26  parallel to axis  18  and located at an intermediate point along return branch  15 .  
         [0017]    In the example shown, axes  18 ,  20 ,  22  and  26  are located successively at the vertices of a trapezium, with axes  18  and  26  located at the opposite ends of the major base of the trapezium, and axes  18  and  22  located at the opposite ends of a diagonal of the trapezium.  
         [0018]    With reference to FIG. 2, conveying device  1  also comprises a compensating device  27 , in turn comprising a guide  28  fitted to frame  12  in a fixed position between sprockets  17  and  23  on one side and sprockets  19  and  21  on the other, and extending in a direction  28   a  parallel to a plane defined by axes  18  and  26  and substantially crosswise to conveying branch  14  and return branch  15 ; and a slide  29  mounted to slide along guide  28 , and which is run along guide  28  by a “brushless” motor  30  controlling a rack-and-pinion coupling (not shown) interposed between slide  29  and guide  28 . Compensating device  27  also comprises a first pair of sprockets  31  fitted to slide  29  to rotate idly about a common axis  32  parallel to axis  18 , and externally engaging a portion of conveying branch  14  extending between sprockets  17  and  19 ; and a second pair of sprockets  33  fitted to slide  29  to rotate idly about a common axis  34  parallel to axis  18 , and externally engaging a portion of return branch  15  extending between sprockets  21  and  23 .  
         [0019]    Conveyor  13  is fitted with a succession of cigar-holder units  35  interposed between and equally spaced along chains  16 . Each cigar-holder unit  35  comprises two opposite, coaxial gripping members  36 , each of which comprises a cylindrical rod  37  parallel to axis  18  and mounted to slide through a respective tubular link-retaining pin  38  of respective chain  16 , and through a hole formed through the end wall of a cylindrical cup  39  integral with one end of relative pin  38  and projecting, coaxially with relative rod  37 , from relative chain  16  towards the other chain  16 .  
         [0020]    An inner end of rod  37  projects from the open end of relative cup  39 , and is force-fitted inside a dead axial end hole  40  of a relative cylindrical gripping head  41  coaxial with rod  37  and having, on the end facing the other chain  16 , a conical seat  42  open on the side facing the other chain  16  and for receiving a respective tapered end  43  of a respective cigar  3  positioned with its longitudinal axis  4  coaxial with rod  37 . A helical spring  44 , coaxial with rod  37 , is compressed between gripping head  41  and relative cup  39 , and is housed, at one end, inside relative cup  39 , and, at the other end, inside an annular groove  45  formed about relative hole  40  and coaxial with rod  37 .  
         [0021]    An outer end of rod  37  projects from the end of relative pin  38  opposite the end connected to relative cup  39 , and is fitted on its free end with a tappet  46 .  
         [0022]    In each cigar-holder unit  35 , the length of rods  37  and relative springs  44  is such as to enable relative gripping heads  41  to move—in opposition to relative springs  44  and when outward axial thrust is exerted on relative rods  37 —from a normal closed gripping position (FIG. 3 b ), wherein relative gripping heads  41  are separated by a distance smaller than the length of cigar  3 , to an open position (FIG. 3 a ), wherein relative gripping heads  41  are separated by a distance greater than the length of cigar  3 .  
         [0023]    Immediately upstream from input  6 , and similarly (in a manner not shown) through output  8 , the axial position of rods  37  of each chain  16  is controlled by a cam device  47  cooperating successively with tappets  46  of relative rods  37  to exert said axial thrust successively on rods  37  and move relative gripping heads  41  temporarily from the closed to the open position.  
         [0024]    As shown in FIG. 3, each cam device  47  comprises a plate  48  fitted integrally to frame  12  and having an inner channel  49 , which is open at the ends, is travelled along by tappets  46 , and communicates externally along its whole length via a slot  50  formed through the surface of plate  48  facing relative chain  16 , and through an undulated lateral surface  51  of channel  49 . Surfaces  51  of plates  48  at input  6  are so shaped as to move relative tappets  46  gradually outwards to open units  35  immediately upstream from input  6  and close them just past input  6 . Similarly, surfaces  51  of plates  48  at output  8  are so shaped as to move relative tappets  46  gradually outwards to open units  35  as they move through output  8 , and close them just past output  8 .  
         [0025]    In actual use, motor  25  is normally operated at constant speed to feed cigar-holder units  35  to input  6  at the same rate at which cigars  3  in input succession  2  are fed to input  6 . As the last cigar  3  in each group  10  is loaded on to conveyor  13 , motor  25  is temporarily accelerated, so that, in the time lapse between the arrival of the last cigar  3  in group  10  and arrival of the next cigar  3 , the portion of conveyor  13  travelling through input  6  is fed through by an amount equal to twice the spacing of cigar-holder unit  35 , thus forming, on conveyor  13 , a gap  11  corresponding to a vacant cigar-holder unit  35  and separating two adjacent groups  10 .  
         [0026]    As motor  25  is accelerated, motor  30  sharply accelerates slide  29  to adjust the lengths of conveying branch  14  and return branch  15  in complementary manner, and so maintain a constant travelling speed V 1  of conveyor  13  through output  8 . In the example shown, in response to each acceleration of motor  25 , slide  29  is moved sharply to the right in FIG. 2 to shorten return branch  15  and accordingly lengthen conveying branch  14 .  
         [0027]    During the time taken to load the next complete group  10 , the sharp movement of slide  29  is followed by a slow movement of slide  29  in the opposite direction, i.e. to the left in FIG. 2, owing to the fact than, when motor  25  operates at constant speed, i.e. when loading group  10 , conveyor  13  moves through input  6  at a constant speed V 2  slower than constant speed V 1 . That is, if each group  10  comprises n cigars  3 , in the time taken by a corresponding n number of cigar-holder units  35  to travel through input  6  at constant speed V 2 , (n+1) cigar-holder units  35  travel through output  8  at constant speed V 1 . Motor  30  is therefore operated to compensate for this difference in speed by gradually shortening conveying branch  14  and lengthening return branch  15  in complementary manner.  
         [0028]    The two movements—sharp rightward to compensate for acceleration of motor  25 , and slow leftward due to the difference between V 1  and V 2 —equal out so that slide  29  oscillates at all times about the same position along guide  28 .  
         [0029]    When a gap  9  in input succession  2  is detected, gap  9  is normally compensated on reaching input  6 , either by temporarily arresting motor  25 , if the missing cigar  3  is one within a relative group  10 , or by maintaining a constant speed of motor  25 , if gap  9  corresponds to a gap  11 .  
         [0030]    If gap  9  is compensated by temporarily arresting motor  25 , motor  30  is operated to move slide  29  sharply to the left to keep speed V 1  constant. This leftward movement of slide  29  is not recovered during operation of conveying device  1 , so that, after a given number of gaps  9  are compensated, slide  29  eventually reaches a leftward limit stop, which arrests motor  25  and cuts off supply of input succession  2 . Sprockets  23  are then made idle, sprockets  17  are locked by a brake not shown, and motor  30  is operated to move slide  29  back to the right-side position.