Method for making a poly-V grooved pulley with interior ribs
This application is a continuation of application Ser. No. 463,718, filed Feb. 4, 1983 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a poly-V grooved pulley, and more particularly to a poly-V grooved pulley with ribs as well as a method of making the same. 
     2. Description of the Prior Art 
     There has been previously employed a poly-V grooved pulley of sheet metal for use with a poly-V belt in a driving system of a vehicle. In a conventional poly-V grooved pulley disclosed in U.S. Pat. No. 3,977,264, for example, a cylindrical flange wall on which a plurality of V-grooves are formed is terminated in an outturned flange so as to strengthen the flange wall. However, such a pulley is comparatively or relatively heavy in weight with the result that torque may not be transmitted efficiently. 
     SUMMARY OF THE INVENTION 
     It is, therefore, a primary object of this invention to provide a lighter poly-V grooved pulley in comparison with the conventional pulley, without decreasing the strength of the flange wall. 
     Another object of this invention is to provide a poly-V grooved pulley provided at an inner surface of a flange wall thereof with a plurality of ribs in the longitudinal or axial direction of the flange wall. 
     In accordance with the present invention, a flange wall of a poly-V pulley may be strengthened or become stronger without increasing the thickness of the flange wall due to the existence of the plural ribs provided thereto. Thus, high torque may be transmitted with efficiency, thinner metal may be employed for forming the pulley with the result that the newly formed pulley may be decreased in weight, and a broad belt or two or three narrow belts operatively connected to different devices may be mounted on the pulley. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary side view of a poly-V grooved pulley, 
     FIG. 2 is a cross sectional view along II--II line of FIG. 1, 
     FIG. 3 is a cross sectional view along III--III line of FIG. 1, 
     FIG. 4 is a fragmentary cross sectional view showing the condition before forming the V-shaped grooves, 
     FIG. 5 is a left side view of FIG. 4, 
     FIG. 6 is a fragmentary cross sectional view showing the condition upon forming the V-shaped grooves, 
     FIG. 7 is a side view of FIG. 6, 
     FIG. 8 is a fragmentary perspective view of a mandrel for increasing the number of the ribs, 
     FIG. 9 is a fragmentary perspective view of a mandrel for changing the cross-sectional shape of the ribs, 
     FIGS. 10 through 13 are views showing a process of making the ribs before forming the V-shaped grooves, 
     FIG. 14 is a view showing a process of making the ribs after forming V-shaped grooves, 
     FIG. 15 is a fragmantary cross sectional view of another pulley to be provided ribs, 
     FIG. 16 is a frgmentary cross sectional view of the pulley of FIG. 15 after being provided with ribs, 
     FIG. 17 is a fragmentary cross sectional view of still another pulley to be provided ribs, and 
     FIG. 18 is a fragmentary cross sectional view of the pulley of FIG. 17 after being provided with ribs. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIGS. 1 through 3, a poly-V grooved pulley 10 has a hub wall 11 and a cylindrical flange wall 12 terminated at a distal end 13. The hub wall 11 is formed with the cylindrical flange wall 12. The cylindrical flange wall 12 is provided at an outer surface 14 with a plurality of V-shaped grooves 15. The cylindrical flange wall 12 is provided at an inner surface 16 thereof with a plurality of ribs 17. Each of the ribs 17 is projected from the inner surface 16 at a height 1 and is elongated along the inner surface 16 by a length L in the longitudinal or axial direction of the inner surface 16. 
     In FIGS. 4 through 7, there is illustrated a method of making the aforementioned poly-V grooved pulley 10 in detail. A source member 20 for the pulley 10 is formed in a substantially cup-shaped configuration from a single metal sheet through a process which is described in the U.S. Patent application filed on June 9, 1982 and having the Ser. No. 386,528, now U.S. Pat. No. 4,468,772 . The member 20 includes a hub wall 21 and a cylindrical flange wall 22 integrally formed therewith, both of which respectively correspond to the hub wall 11 and the cylindrical flange wall 12. 
     Above the cylindrical flange wall 22 is located or positioned a spinning roller 30 having a plurality of cutting edges 31 in opposition to an outer surface 23 of the cylindrical flange wall 22. Within the cylindrical flange wall 22, there is loosely installed a mandrel 35 divided into four segments 35a, 35b, 35c and 35d (only 35d is not shown) in the circumferential direction. An annular groove 36 is provided in a side facing the hub wall 21 of the source member 20 and is divided into four sections 36a, 36b, 36c and 36d all of which respectively correspond to the segments 35a, 35b, 35c and 35d. An annular ring 37 is fitted in the groove 36 so as to reduce the radius of the mandrel 35 or to form a clearance 38 between an inner surface 24 of the cylindrical flange wall 22 and an outer surface 39 of the mandrel 35. 
     The mandrel 35 is also provided at a center portion thereof with a tapered bore 40 whose diameter gradually increases in the rightward direction as seen in FIG. 4. Between any two adjacent segments of the mandrel 35, there is formed a radial clearance 41 (FIG. 5). A member 42 is located at a right side of the mandrel 35 and the source member 20. 
     In operation, when the rotating roller 30 is brought into engagement with an outer surface 23 of the source member, V-shaped grooves are formed. Simultaneously with the above, when a tapered bar 50 is fitted in the tapered bore 40 of the mandrel 35, the mandrel 35 is expanded in the radial direction with the result that the outer surface 39 of the mandrel 35 is brought into abutment with the inner surface 24 of the source member 20, and clearances 41 between any two adjacent segments of the mandrel 35 are expanded in the circumferential direction. Thus, by further expansion of the mandrel ribs 17 are projected or extended from the inner surface 24 of the member 20 into the expanded width clearances 41. 
     As seen from FIG. 8, further ribs (not shown) may be formed in addition to the ribs 17 by providing cutout portions 18 on the outer surface 39 of the mandrel 35. Each of the ribs 17 may be changed in shape by expanding an opening of the clearance 41 due to a pair of opposed longitudinally half-rectangular notches 41a on the adjacent segments 35a and 35b (FIG. 9). 
     The ribs 17 may be formed prior to V-grooves formation by using expandable mandrels 35, a roller 60, and the member 42, as seen from FIGS. 10 through 13. On the contrary, the ribs 17 may be formed after forming of V-grooves as seen from FIG. 14 wherein the mandrel 35 is expanded with the roller 30 resting on the flange wall 22. In each case the roller 30 is used for forming the V-shaped grooves. 
     The ribs 17 also may be formed on an inner surface 22 extending transversely of plural V-shaped grooves 70 for reducing weight of the pulley 10 as seen from FIGS. 15 and 16. In the case that two sets of plural V-shaped grooves 15a and 15b are formed on the outer surface 24 of the flange wall 22 as well as corresponding sets of inner plural grooves 70a and 70b being formed on the inner surface 24, each of the ribs 17 is divided into two portions 17a and 17b as shown in FIGS. 17 and 18.