SPECIFICATION
Roller assemblies for conveyors The present invention relates to roller assemblies for roller conveyors and, more particularly, for so-called power and free roller conveyors in which the rollers are driven to advance articles or parts along the conveyor and can also free-wheel to accommodate a stoppage of parts on the conveyor, such as, may occur at the discharge end of the conveyor preparatory to removal of the parts for subsequent processing.
In power and free conveyor structures, the drive is normally transmitted from the roller support shafts to the rollers by means of friction. Whilst existing constructions provide sufficient friction between the components of the roller assembly to drive parts along a horizontal conveyor, there is insufficient friction between the components to prevent backwards bounce of a conveyed part upon abutting a stop located along the conveyor, or a preceding stopped part, and this can result in switching or control problems where it is necessary to stop a conveyed part precisely in a predetermined position, for example, for the purposes of subsequent processing. Moreover, there is insufficient friction between the components of existing constructions to permit controlled advance of a conveyed part other than in a horizontal plane.
It is an object of the present invention to alleviate these problems of existing roller conveyor constructions. To this end, the invention consists in a roller assembly for a roller conveyor, comprising a collar for mounting on a roller support shaft of the conveyor and having a radial flange at one end, an annular cap mounted on the opposite end of the collar, and providing an opposing radial flange, means for securing the collar and cap to the shaft, and an annular roller rotatably mounted on the collar between the radial end flange thereof and the cap, said collar, cap and roller being formed as sintered components from material including a major portion of iron.
When the invention is used in the construction of a power and free conveyor, sufficient friction is produced between the sintered components of the roller assemblies, under the action of the weight of a part being transported by the conveyor, substantially to eliminate the problem of bounceback experienced with prior constructions. Also, sufficient friction is produced so as to allow a conveyor embodying the invention to transport parts up and down an incline without losing drive control of the parts. For example, the invention enables a conveyor to be inclined 5[deg] either upwardly or downwardly without losing drive control. Moreover, the roller assembly according to the invention is capable of working under most conditions experienced in manufacturing plants, such as, in the presence as cutting oil, soluble oil, swarf or dust, without adversely affecting its drive parameters.Also, the roller assembly may readily be attached to its support shaft and the latter requires no special machining or treatment.
Untreated steel stock bar may be employed. For example, it may simply be secured to its support shaft by a pin projecting through the shaft, collar and cap, the pin also serving to fasten the cap to the collar.
Preferably, the roller has axially projecting circumferential flanges which overlap the radial joints or gaps between the roller and the collar end flange and cap. These circumferential flanges prevent ingress of dust, swarf etc. to the bearing surfaces between the roller, collar and end cap.
They may be in rotary contact with the collar flange and cap and serve to enhance the friction drive between the driving components, namely, the collar and cap, and the driven roller.
In order that the present invention may be more readily understood, reference will now be made to the accompanying drawing which illustrates a cross-section through a power and free conveyor embodying the invention. The right hand side of the drawing illustrates an embodiment in which the roller assemblies are mounted on a driver support shaft extending across the full width of the conveyor, whilst the left hand side illustrates an arrangement in which the roller assemblies are supported on stub shafts.
Referring to the drawing, the power and free conveyor comprises an elongated platform 1 mounted on a base support 2. Extending along opposite sides of the platform 1 are rails 3 of generally "I" section mounting roller support shafts extending transversely of the platform.
These shafts may be full width shafts 4 journalled at opposite ends in rolling bearings 5 in the rails 3 as illustrated on the right hand side of the drawing, or stub shafts 6 journalled in two rolling bearings 7 in the adjacent rail, as shown on the left hand side of the drawing. Each shaft 4 projects through one of the rails 3 and has a bevel gear 8 secured to its projecting end and meshing with a bevel gear 9 fastened to a driving shaft 10 disposed along the outside of the rail and housed in a casing 11 secured to the rail. Each stub shaft 6 projects through the adjacent rail and similarly has a bevel gear 8 on its projecting end meshing with a bevel gear 9 on a driving shaft 10 projecting along the outside of the adjacent rail 3 and housed in a casing 11.
In either case, the roller assembly supported on the shaft 4 or 6 is the same and comprises a collar 12 mounted on the shaft and having a radial end flange 13 at its inner end, an annular cap 14 mounted on the outer end of the collar with its skirt 15 serving as a radial flange at the opposite end of the collar, and a roller 16 freely rotatable on the collar between the end flange 13 and the cap skirt 15. The latter is of the same depth as the collar end flange 13. The collar and cap are secured to one another and the shaft by a pin 17 projecting through the shaft and diametrically opposite holes in the collar and cap. The roller has axially projecting circumferential flanges 18 at opposite ends which overlap the joint or gaps 19 at the collar end flange and the cap skirt to prevent ingress of dust, swarf etc. into the rotary bearing surfaces between the components.These circular flanges are in rotary contact with the collar flange and cap.
In the case of the stub shaft 6, spacer washers 20 may be mounted on the shaft between the cap and the adjacent rolling bearing 7 and in conjunction with the bevel gear 8 restrain axial movement of the stub shaft. The collar 12, cap 14 and roller 16 are all formed as sintered components from materials including a major portion of iron.For example, in a preferred embodiment, the collar is sintered from a powdered material marketed by Firth Cleveland Products Ltd. under the specification code S20 and comprising a minimum of 96% iron, 0.5-1 % carbon and a maximum of 3% other elements, the cap is sintered from a material marketed by the same company under the code F10 and comprising a minimum of 98% iron and a maximum of 2% other elements, and the roller from a material having the code N30 and comprising a minimum of 90.2% iron, 0.5-2% copper, 1.0-3% nickel, 0.4-0.8 molybdenum, 0.4-1 % carbon and a maximum of 3% other elements.
The conveyor illustrated is intended for the transport of automobile parts, such as, cylinder heads, on pallets 21. These pallets are supported on the rollers 16 which project through a cover plate 22 secured between the rails and is centralised on the conveyor by guide bars 23 projecting inwardly from the upper flanges of the rails. The rollers 16 are normally freely rotatable on their associated collars 12. Under the action of the weight of a pallet loaded with a part, sufficient friction is produced between the sintered components of the roller assemblies to cause drive of the rollers and, hence, transport of the pallet along the conveyor. When the pallet abuts a stop in a processing position, the collar and cap of each roller assembly continue to turn together with the associated shaft and independently of the roller which remains stationary.Upon engaging the stop, sufficient friction is still developed between the sintered roller and the sintered collar and cap to prevent bounce-back of the part on the rollers so that the pallet remains stopped in the desired position. Moreover, with the particular embodiments described, the conveyor can be inclined 5[deg] either upwardly or downwardly without loss of drive to a pallet.
Whilst particular embodiments have been described, it will be understood that modifications can be made without departing from the scope of the invention. For example, in certain circumstances it is conceivable that the cap 14 may be omitted.