Abstract:
A drum for a brush roller comprised of a plurality of arcuate shaped segments with circumferentially projecting shoulders at their ends. The shoulders have outer edges that contact the adjacent segments and have respective inwardly and outwardly facing surfaces which in adjacent segments overlie and are attached together. Each segment has radially spaced double walls with sufficient rigidity and has reinforcement. The outward side of each segment is provided with a plurality of protruding beams defining U-shaped channels between them. An axle includes the drum with end plates and projecting shafts at each end. Also, a method of assembling the drum wherein the edges of the shoulders are brought against adjacent segments and the shoulders have their respective inwardly and outwardly facing surfaces overlying and fastening elements extend through the shoulders.

Description:
TECHNICAL FIELD 
     The invention relates to a drum as axle in a brush roller. Brush rollers are used for cleaning large flat surfaces and also in industrial context for deburring, polishing or roughening surfaces or edges. 
     BACKGROUND ART 
     It is well known that axles for brush rollers, particularly brush rollers used in road cleaning machines, are difficult to manufacture. These brushes generally have a length of between 1.5 to 4 meter and a diameter of between 700 and 1800 mm. The brushes rotate at a speed of between 400 and 1000 r/m. 
     The traditional method of manufacturing the axle of a brush roller is to attach axial holders on a steel pipe or rod, at the periphery of the pipe. Various types of brush magazines are then fitted in these holders. These axial holders are generally made of extruded aluminium. Other components included in such a brush roller are various forms of key joints and spacers. The steel pipe and spacers are welded together with known precision. A large number of holes for attachment bolts must also be drilled and threaded in the steel pipe. This vast number of components entails high storage costs for material as well as expensive machining costs. 
     Commercial alternatives available are to design the axle of the brush roller as a fully extruded aluminium section. One problem is that the die used for the extrusion is limited as to size so that only certain maximum diameters can be produced. Furthermore, these extruded aluminium sections are extremely heavy since the material is thick, and it is impossible to reduce their mass by inserting cavities. A considerable drawback when extruding aluminium sections is the banana shape the section acquires on the cooling bed. A section that is 4 meter in length may have a curvature of 4 mm or more. This curvature entails extra work at the dynamic balancing. 
     It is also known through U.S. Pat. No. 3,134,123 and U.S. Pat. No. 3,862,463 to make the cylindrical axle of the brush roller in segments, which are joined together and anchored, to hub members situated centrally at the ends of the axle. The segments are in the form of thin-walled sections, which are not reinforced in axial direction, and the axle is therefore limited in both length and diameter. This method of constructing the axle of a brush roller does not permit the manufacture of long axles, e.g. 4 m, nor axles having large diameter, e.g. 1200 mm, because of the unbalance occurring at the revolution speeds involved. U.S. Pat. No. 3,134,123 also indicates that the embodiment shown in FIG. 3 constitutes a self-supporting construction. However, this construction is extremely expensive since the dovetail joints of the sections cannot be manufactured without after-working, with the tolerances necessary if the joints are to be free from play. Furthermore, the dovetail form according to U.S. Pat. No. 3,134,123 must have a certain play to enable one section to be axially inserted into another section, and this per se results in play in the construction. 
     OBJECT OF THE INVENTION 
     The object of the invention is to solve the problems mentioned above and to improve a drum in the axle of a brush roller so that the axle becomes simpler and less expensive to manufacture, as well as being lighter, which contributes to increased stability at the bearing housings of the axle. 
     Another object of the invention is to provide a drum for the axle of a brush roller which drum, under dynamic loading, behaves as a rigid cylinder. 
     A further object of the invention is to provide a drum for a brush roller with relatively large diameter and length, which can be produced from extruded aluminium sections and which, after assembly, performs entirely free from play and with a rigidity equivalent to a homogenous body, e.g. a cylinder. 
     SUMMARY OF THE INVENTION 
     The objects stated above are achieved and the drawbacks eliminated by means of the present invention as defined in the claims. 
     The method for assembling a drum according to the inventive concept is that the drum forms a part of an axle and that the axle constitutes a part of a brush roller. Characteristic of the assembly is that an axle consists of a drum on which an end plate with two shaft ends have been mounted. 
     The drum preferably has circular cross section. A plurality of axial, preferably U-shaped channels are arranged at the periphery of the drum. A normal axle has 16 channels but the number of channels may be either more or fewer. The drum is preferably made from four segments of extrude aluminium sections. 
     The number of segments is in no way limited to these four segments but may vary from two or more, e.g. 2, 4, 6 or 8. An even number of sections is preferable in order to achieve dynamic balance in the simplest manner at rotation. The segments exhibit an outer arc shape. Four segments, for instance, are fitted together to form a drum. Each segment has a first edge part with a first shoulder and a second edge part with a second shoulder. 
     Assembly of four segment sections to a drum is as follows: 
     In a first step each segment is arranged so that the edge portion of the first shoulder and/or the edge portion of the second shoulder are in contact with the second or first contact surface, respectively, of an adjacent segment. This ensures that the drum will always have the same diameter. A space between the various segments may cause unbalance. The contact surfaces between the shoulders of the segments are flat so as to obtain the greatest possible contact area without having to machine the surfaces. Alternatively the contact surfaces of the shoulders may be provided with pins and recesses in order to a greater extent to take up tangential shear stress between the segments. 
     A variant of the shape of the segments is to arrange two adjacent segments with the lower side of the second shoulder of a first segment in contact with the upper side of the first shoulder of a second segment. 
     This is done when the shoulders of the segments are at different levels, i.e. radial distance from the axis of rotation of the axle. An alternative embodiment is the use of two differently shaped segments, alternate segments being identical, i.e. the shoulders on alternate segments are at equal radial distance from the inner arc. 
     Another factor is that each section is curved at the extrusion. By dividing the drum into segments, the curvature of the segments will be compensated and the drum becomes straight. At one and the same extrusion process each rod will be cooled in the same way and each will acquire similar defects. 
     A second step entails drilling or drilling and threading through-holes in radial direction, e.g. through the first, outermost shoulder as a clearance hole and through the second, innermost shoulder as a threaded hole, in each segment. Two or more holes are drilled along the segments in each shoulder, at equal or different distances from each other. 
     The third step entails passing an attachment element, a bolt or a screw and nut, through each hole. This screw joint ensures complete freedom from play, which is necessary if a brush roller 2.5-6.0 meter in length is to be balanced dynamically and then withstand a continuous speed of revolution of up to 1200 rpm. 
     When the drum is mounted on the axle, a circular plate with a concentrically arranged shaft end is fitted on the end portions of the drum. Congruence exists between every or every other segment incorporated in a drum. The advantage of having only one shape for the segments in the drum is to save costs. 
     The segments incorporated in a drum exhibit the following characteristics: 
     the segments consist of extruded aluminium sections; 
     a segment exhibits an outer arc form; 
     each aluminium section is provided on its upper side with two or more, preferably four, radially protruding beams; 
     a U-shaped channel is formed between two adjacent beams; 
     each segment has a first shoulder and a second shoulder. 
     In one embodiment the upper side of the first shoulder and the lower side of the second shoulder of a segment preferably have flat surfaces. 
     The segments are also made double-walled, one or more cavities being formed in each segment. In a segment with two cavities, these cavities are separated by radially reinforced spacers extending axially along the entire length of the segment. The U-shaped channels of the segment are also situated radially in relation to the imagined central axis of the drum. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the invention is shown schematically in the accompanying drawings in which 
     FIG. 1 shows an axle with its drum and two shaft ends, 
     FIG. 2 shows an end part of a drum including a number of brush magazines inserted into slots, 
     FIG. 3 shows an embodiment of a brush magazine 
     FIGS. 4A-B show a segment 
     FIG. 5 shows a section from FIG. 3 through a join between two segments revealing hole and bolt. 
     FIG. 6 shows a view A—A in FIG. 1 of an end part of the axle of a brush roller. 
    
    
     DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates an axle  1  seen from the front, built up of a drum  2  and two shaft ends  3 ,  4 . Each shaft end  3 ,  4 , which may have the form of part of a spline joint, is mounted on a torque transmitting plate  50  which in turn covers the end part  22  of the drum  2 . Two shaft ends  3 ,  4 , each with a-plate  50 , together with a drum  2 , constitute the axle  1  of a brush roller. 
     FIG. 2 shows an end part of the drum  2 , the drum  2  in this embodiment comprising four segments  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4 . The drum  2  is formed by the four segments  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  after assembly. The segments  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  are produced from an extruded aluminium section. Each segment  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  is provided on its upper side  8  with four radially protruding beams  9 . 1 ,  9 . 2 ,  9 . 3 ,  9 . 4 . In order to reduce manufacturing costs, the segments  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  are congruent with each other. 
     In a drum  2  assembled from four segments  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  there are sixteen U-shaped channels  10 . 1  . . .  10 . 16 , arranged so that a U-shaped channel  10 . 2  is produced between two adjacent beams  9 . 1 ,  9 . 2 . Similarly, the channels  10 . 1 , . . .  10 . 16  are arranged between the adjacent beams  9 . 1 , . . .  9 . 16 . Rows of brush magazines  13  in which brushes are fitted, are shown in the U-shaped channels  10 . 8  . . .  10 . 11 . Eight circular, threaded holes  21 . 1 , . . .  21 . 8  intended for use when assembling the plate  50  with its shaft ends  3 ,  4  to the end part  22  of the drum  2  are also arranged axially in each segment, preferably in the area below a beam near the ends of the segment. The drum is arranged to rotate about its central axis  12 . 
     FIG. 3 shows an embodiment of a brush magazine  13  comprising a holder  14  for five brushes with card wire  15 , pressed into a plastic holder  16 . 
     FIGS. 4A and 4B show an individual segment  7 . 1  with its extruded aluminium section, seen from the end. When an aluminium section  7  is extruded through a die, all the holes in the die will give the aluminium section  7  an elongate shape. The pattern of holes in a die corresponds with the cross section of the section. In order to reduce the cost at manufacture, as well as the weight, and to increase the rigidity of the section  7 , the section is provided with a number of cavities  20 . 1 - 20 . 6 , four of which are situated in the beams  9 . 1 , . . .  9 . 4 , and two in the section  7 . The two cavities  20 . 2 ,  20 . 4  in the section are formed by the section having double walls and the cavities being separated by radially reinforced spacers  60  extending axially along the entire length of the segment. In this example there are two more holes—the two circular, threaded holes  21 . 1 ,  21 . 2  intended for use when assembling the plate  50  with its shaft ends  3 ,  4  to the end part  22  of the drum  2 , see FIG.  1 . Each beam  9 . 1  . . .  9 . 4  in the segment  7 . 1  exhibits a first side part  25 . 1  and a second side part  25 . 2 , each with a longitudinal slot  26 . 1 ,  26 . 2 . Each slot  26 . 1 ,  26 . 2  in each beam  9 . 1 , . . .  9 . 4 , is at the same distance from the central point  12  of the drum. The openings of the slots  26 . 1 ,  26 . 2  face the U-shaped channel  10 . 1  . . .  10 . 16 . The openings  11  of the U-shaped channels  10 . 1  . . .  10 . 16  face away from the centre  12  of the drum  2 . 
     The outwardly facing surfaces  27 . 1  . . .  27 . 16  of the beams  9 . 1 ,  9 . 2  when the segments  7 . 1  . . .  7 . 4  are assembled to a drum  2 , are at a tangent to a circumscribed circle  28 . Each segment  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  has an outer arc shape  28 A. One segment  7 . 1  in this example shows an inwardly facing surface  29  which also has an arc shape. Both the circumscribed circle  28  and the inwardly facing arc-shaped surface  29  have the same radial centre  12 . A first shoulder  35  is arranged on the section  7 , tangentially outside the first beam  9 . 1 , and a second shoulder  36  is arranged on the section tangentially outside the fourth beam  9 . 4 . The surfaces of the upper side  37  of the first shoulder  35  and the lower side  38  of the second shoulder  36  are preferably flat but may also assume an arc shape with a common radius  39 . The centre of the radius  39  is at the centre  12  of the drum. The width “b1-b2”, i.e. the distance from the inner corner b2 between the upper side  37  of the shoulder  35  and a first radial contact surface  40  on the first beam  9 . 1  to the outer corner b1 of the shoulder  35  is preferably equal to the width “b3-b4”, i.e. the distance from the inner corner b3 between the lower side  38  of the second shoulder and a second radial contact surface  41  below the fourth beam  9 . 4  to the outer corner b4 of the shoulder  36 . 
     The outside of the preferably upwardly directed part at the upper side  37  of the first shoulder  35  is thus designated a first contact surface  40 . The outside of a preferably radially downwardly directed part at the lower side  38  of the shoulder  36  is corresponding designated a second contact surface  41 . 
     The first shoulder  35  is provided with a first edge part  42 . This edge part  42  extends from the lower side  29  of the shoulder  35  to its upper side  37 . The second shoulder  36  is provided with a second edge part  43  extending from the lower side  38  of the shoulder  36  to the upper side  44  of the shoulder  36 . 
     Assembly of the drum  2  is performed as follows: 
     a) four segments  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4 , FIGS. 4A,  4 B, are arranged close to each other as shown in FIG. 2 in such a way that the upper side  37  of the first shoulder  35  of a segment  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  is brought into contact with the lower side  38  of a second shoulder  36 ; 
     b) the first shoulder  35  of each segment  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  and its first edge part  42  are brought into contact with the second contact surface of adjacent segments  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4 , see FIG. 2; 
     c) the second shoulder  36  of each segment  7 . 1 ,  7 . 2 ,  7 . 3 ,  7 . 4  and its second edge part  43  are brought into contact with the first contact surface  40  of adjacent segments, see FIG. 2; 
     d) an alternative to b) and c) is for either a first edge part  42  to be in contact with a second contact surface  41  or a second edge part  43  to be in contact with a first contact surface  40 ; 
     e) holes  45 ,  46  are drilled and threaded in radial direction, FIGS. 4A,  4 B, through each first  35  and second shoulder  36 . 
     f) a plurality of holes  45 ,  46  are drilled at equal or different axial distance from each other; 
     g) an attachment element  47 , FIG. 5, bolt, is arranged through each hole  45 ,  46  in such a manner that a friction joint is obtained between the shoulders  35 ,  36  at the contact surface  37 ,  38 . 
     FIG. 5 shows a section through a joint in FIG. 2 between two adjacent segments  7 . 1 ,  7 . 2 . The section shows that the segments have been assembled using a screw joint, the second shoulder  36  of one segment  7 . 1  having a throughhole radially-aligned with a threaded hole through the first shoulder  35  of the second segment  7 . 2 . An attachment  47  in the form of a bolt, i.e. a machine screw, is screwed through these holes. The flat contact surfaces  37 ,  38  are thus pressed against each other, see FIG.  2 . The upper side  44  of the shoulder  36  is also flat in order to provide the best possible contact surface for the attachment element  47 . 
     FIG. 6 shows a view A—A in FIG. 1 with part of the plate  50  removed. The figure shows the end of the axle  1  with its shaft end  3  arranged concentrically with the plate  50 . Holes  52 .n are arranged at the periphery  51  of the plate  50 , where n=1, . . . 8, for a second attachment element  53  in the form of an axially fitted bolt. The distance between the holes  52 . 1  . . .  52 . 8  corresponds to the distance between the threaded holes  21 .n, where n=1, . . . 8, at the end part  22  of the drum  2 . 
     Assembly of the plates  50  with their shaft ends  3 ,  4  to the drum  2  is performed as follows: 
     a) a shaft end  3 ,  4  and its torque-transmitting plate  50  is arranged at each end part  22  of the drum  2 ; 
     b) the shaft ends  3 ,  4  with plate  50  are arranged concentric with the end part  22  of the drum  2 ; 
     c) the attachment element  53  is screwed through the holes  52 . 1 , . . .  52 . 8  in each plate  50  and into the holes  21 . 1 , . . .  21 . 8  in the end part  22  of the drum  2 . 
     The invention is not limited to the example described but can be used in all drums built up of segments to be used as part of an axle where each segment is in the form of an extruded section and where each segment has two shoulders that are united with an attachment element. The invention is not limited to a certain number of segments but applies to all segments amounting to two or more. Neither is the invention in its widest scope limited to the drum assuming the shape of a cylinder. It may also assume the shape of an equilateral polygon.