REINFORCED CUBE, PULLEY AND METHOD DESCRIPTION OF THE INVENTION: This invention relates to a metal foil pulley made by rotary rolling molding, but more particularly the invention relates to a centrifuged pulley with a reinforced bucket and a method for making the pulley Pulleys with a foil cube can be formed by pressure molding using a series of dies or forming mandrels or rollers or a combination thereof. For example, a pulley with an integral hub that is molded by pressing is presented in U.S. Patent 4,824,422 to Jocic, wherein the hub has an integral flange that facilitates removal of the pulley from an ov stem, The slots that receive the band are formed by rotation in the pulley ring. A field of problems with the pressing molding process when making the integral cube that is pulled in the pressure molding process, whereby the radial thickness of the cube becomes the same or thinner than the thickness of the sheet. which is molded. It is often difficult to control the size of a hole to receive a shaft without some additional metal forming process such as machining or size by pressing a ball through the hub bore. Another problem with the pressure molding process is that the cube can not be reinforced along its axis unless, perhaps, a folding process is used. Folded metal shapes and reinforcements introduce high stress areas that are subject to crack failure or fracture under the effect of fatigue. German patent No. 4 444 526 granted to WF
Maschinenbau presents a method for forming a cube by rotation or skating where a forming cylinder is pressed against one side of a rotating annular blade disc which is supported on the opposite side by a head chuck mandrel. The forming cylinder moves progressively radially inwardly against the side of the rotating disc which displaces a portion of metal as the part of the disc is thinned and forms a side wall having a thickness that is less than the original thickness of the disc. the sheet. An annular undulation is formed as the metal moves and progressively extends axially. A forming roll or cylinder presses the metal thus annularly displaced against the mandrel while simultaneously forming the integral hub with the disk. A problem with the hub formed by rotation is that it tends to spring back to a larger diameter in areas where the hub has little or no support causing a slight taper in the hub bore. The maximum allowed variation of the internal diameter of a cube pressing applications is 0.03 mm and such formed cube has approximately 0.1 mm variation. Such cubes need further processing and size such as a ball end or a machining (this is a reaming) to adjust an axis. A pulley with an integral hub according to the present invention is molded by centrifugal rolling, wherein a sheet portion is displaced radially and axially from one side of the disc, leaving or producing a rib. The hub thus formed has at least one annular ring integral with the hub and has a diameter that is larger than the outer diameter of the hub. The ring provides a reinforcement that prevents spring back. Optionally the hub can include an integral flange of a size that facilitates the removal of the pulley from an axis. A ring or ring extends from the ring and can have any desired configuration for coupling with a transmission band such as a V-ribbed band. In the process of the invention, a forming cylinder is pressed against one side of an annular disc rotating blade. The forming cylinder moves progressively radially inward against the side of the rotating disc that displaces a portion of metal in the form of an annular undulation extending axially. The metal so displaced is pressed by a cylinder that moves axially against a mandrel to form a hub that is integral with the core. The forming cylinder includes at least one annular groove in which the metal flows forming an integral reinforcement ring for the hub. The integral ring reinforces the bucket enough to bring the springback to a minimum or to eliminate later processes of giving size to the drill. Optionally the hub includes a radial flange that facilitates the removal of the pulley from an axis. A radially protruding portion of metal is formed against the cylinder against the roller or cylinder as the hub is formed. Optionally, the protruding portion of metal can be used to form an integral flange with a hub when pressing a finishing cylinder against the protruding metal. An object of the invention is to provide a pulley with a hub having sufficient strength, with which you do not need additional machining to fit the size of an axis. Another object of the invention is to provide a pulley and a method for manufacturing the pulley with a flange that facilitates removal of the pulley from an axle. These and other objects of the invention will be seen by looking at the drawings and reading the following description, wherein: DESCRIPTION OF THE DRAWINGS Figure 1 is a diametrical cross-sectional view of a pulley and a bucket according to the invention; Figure 2 is an enlarged view taken along line 2-2 of Figure 1 showing a hub according to the invention; Figure 3 is a schematic sectional view illustrating the key elements of a rotary rolling forming machine and an annular disc placed on the machine for modeling by turning displacement; Figure 4 is a view similar to Figure 3 but showing a machine in a progressive operational step; Figure 5 is a view similar to Figure 3 but showing a machine in a progressive operational step; and Figure 6 is a view similar to Figure 2 but showing a final operation of the mold by roll turning and the formation of a hub for a pulley according to the present invention; Referring to Figures 1 and 2, a one-piece pulley 10 according to the invention has a hub 12 which is integrated with a core 14 wherein the hub and the core are formed by spinning centrifugally from a sheet disc. A ring 16 extends from the hub and can have any desired configuration to operate with a power transmission band (not shown). A V-ribbed pulley is illustrated where there is a plurality of V-grooves 18 to receive a V-ribbed band. The hub includes at least one or more annular reinforcement rings 20 integral with hub 12 and extending radially outward from the hub. an outer diameter 22 of the hub. The reinforcing ring has a suitable size and is located to prevent "backward springing" of the hub after the spin modeling process so that the bore B of the hub has a negligible taper, thereby which does not require additional machining to maintain a diameter D, which is within the tolerance to put an axis (not shown) Optionally a radial flange 24 with a radial thickness
may extend from the open end 26 of the hub and be formed integrally from the hub during the modeling process b by rotation. The hub 12 of the invention is integrally formed in the web 14 having a thickness 28, and has a wall thickness of hub 30, a thickness of ring reinforcement 32, a ring reinforcement width 34, a length of hub 36 and a ring 20 at a distance 38 from the open end 26 of the hub. Of course, the reinforcing ring may have the shape that is desired, as long as it prevents the "springing back" of the cube after forming. A cube of the invention was made with the dimensions indicated in Table 1 and where the hole B of the hub did not need additional machining to maintain an acceptable diameter. TABLE 1 Core thickness 3 mm Wall thickness cube 4 mm Thickness reinforcement ring 1.4 m Width reinforcement ring 3.6 mm Cube length 24 mm Internal diameter 15.94 -0 +0.03 Place of center ring Length Radial thickness flange 3.5 mm
The drill thus manufactured has a taper of less than 0.07 degrees while the prior art hubs without rings have a taper of approximately 0.03 degrees. In other words, the drill thus manufactured has an internal diameter variation of 0.03 mm or even less. Referring to Figures 3-6, an annular disk 40 having a thickness 41 is positioned to be worked with a spinning modeling machine 42 which includes a chuck head mandrel 44, a reciprocably movable chuck 46, a first cylinder or forming roller 48, a holding roller 50, a second forming or finishing roller 52. In Figure 3, the annular disk 40 is placed on a pilot 54 of the die head mandrel 44 where the outer diameter of the pilot is dimensioned for an internal diameter D of the hub to be manufactured. The mandrel 44 has a cylindrical recess 56 dimensioned to receive the outer diameter 58 of the disc and the recess has a depth 60 that is less than the thickness 42 of the disc. The mandrel 46 has a bore 62 which receives a pilot, an external diameter 64 and a radial step 66 dimensioned for a desired internal flange of the hub to be formed, the mandrel 46, the first forming cylinder 48, the holding cylinder 50 and a second forming roll 52 are positioned remote from the die head mandrel 44 in an initial position to facilitate loading and positioning of the annular disk 40 on a pilot and against the mandrel 44. Figure 4 shows the spinning roll forming machine. 42 in an intermediate gear position wherein the annular disc 44 is being formed, such that upon completion, it will include an integral hub with an annular ring to reinforce the hub. The mandrel 46 moves in an axial direction M so that the pilot 54 engages with the bore 62 to receive it. The holding roller 50 is shown in the working position where it moves in the H direction so that a cylindrical surface 68 presses against an exposed annular portion 70 of the disc to stop it in a sandwiched position against the die head mandrel. The forming cylinder 48 is transferred to its forming position by first moving it in a SA direction so that a rounded edge 72 of the forming cylinder presses against the disc. The mandrel and the head die are rotated which rotates the disc. The retaining roll or cylinder 50 and the forming roll 48 are free to rotate and rotate the disc. The forming roller with its rounded edge 72 displaces a portion of the metal of the disc which is supported on its opposite side for the head chuck mandrel. The forming cylinder moves progesively radially inward against the side of the disc that displaces metal from a disc side to form a core having a thinner side wall 76 than the sheet. the forming cylinder progressively forms a ripple 78 of the displaced axially extending metal. Referring to Figure 5, the forming roller continues to move progressively radially inward in the direction SR2 and the displaced metal is axially elongated and comes into contact with the tapered surface 80 of the forming roll. The tapered surface is oriented so as to be substantially parallel to the axis of the head chuck mandrel 44 and the mandrel 46. The contact with the tapered surface causes the corrugation to take an initial form of hub 90. The tapered surface of the forming roller 48 also it includes an annular groove 92 having a positioning and a shape dimensioned so that a sought reinforcement ring 20 is formed. The forming roller or roll may also include a tapered edge on the front side 94 for preforming an integral flange. The radial movement inward of the first forming cylinder is stopped at a predetermined position as it approaches the mandrel 46. As shown in Figure 6, the second forming or terminating roller of the hub 52 is activated and placed with a tapered surface 98. against the displaced metal that forms the cube. The surface 96 is arranged to be substantially parallel with the axes of the rotary head die mandrel 44 and the mandrel 46, when in contact with the displaced metal forming the hub, the tapered surface of the terminator roller also includes an annular groove 98. with a shape corresponding to the shape of the reinforcing ring to be formed. A step 100 can optionally be formed in the finishing roller 52 and has a configuration sized to model the radial flange 24. The diameter 64 of the mandrel 46 corresponds to the diameter of the flange 24 that is produced. The disk thus formed 104 as shown in
Figure 6 is removed from the machine for the following processing steps, an annular portion 106 is separated and bent by known processes in the ring configuration illustrated in Figure 1. There are many changes and variations without departing from the spirit and scope of the present invention, and the description has only been a preferred illustrative example.