Patent Publication Number: US-6907764-B2

Title: Methods and apparatus for manufacturing flanged articles

Description:
This application claims priority to Japanese Patent Application Serial Number 2001-300399, the contents of which are hereby incorporated by reference herein. 
   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to methods for manufacturing a flanged article from a sheet material. More particularly, the present invention relates to methods for manufacturing a flanged article from a sheet material by utilizing a press forming machine. 
   2. Related Art 
   A known method for manufacturing a flanged article is taught, for example, by Japanese Laid-open Patent Publication Number 10-202329, in which a toothed recessed plate or ratchet plate for a seat reclining device of a vehicle is exemplified as a flanged article that can be prepared utilizing the known method. In this known art, a disk-like sheet material or sheet blank is placed and clamped between upper and lower dies of a press forming machine. Thereafter, a punch associated with the upper die is lowered by a predetermined distance toward a corresponding die opening defined within the lower die. As a result, the sheet material is press formed or half die cut, to thereby form the ratchet plate that comprises a central depressed body and a peripheral flange. The peripheral flange of the ratchet plate is integrally connected to the central body via an annular shear deformed connecting portion. As a result, the peripheral flange and the central body define a circular open cavity or recess. Further, two tooth forming edges are circumferentially defined on the punch. Therefore, a pair of toothed portions can be formed on the inner circular surface of the peripheral flange when the sheet blank is press formed. 
   According to this known method, when the sheet material is half die cut by the punch, the sheet material is compressed and deformed along the periphery of the punch. As a result, the compressed sheet material may partly move towards the shear deformed connecting portion due to plastic flow, to thereby prevent the shear deformed connecting portion from cracking. However, the central body will have substantially the same thickness as the peripheral flange, which thickness is substantially equal to the thickness of the sheet material. 
   SUMMARY OF THE INVENTION 
   It is, accordingly, one object of the present teachings to provide improved methods and apparatus for manufacturing flanged articles. 
   In one embodiment of the present teachings, methods are taught for manufacturing a flanged article that comprises a central depressed body coupled to a peripheral flange. For example, a material (e.g., a sheet material or a sheet blank) may be press formed in order to form an intermediate flanged article that comprises a central depressed body and a peripheral flange. Then, the peripheral flange of the intermediate flanged article may be circumferentially squeezed in order to thicken the peripheral flange as a result of plastic flow caused by plastic deformation. 
   In another embodiment of the present teachings, at least one toothed portion may be formed on an inner surface of the peripheral flange when the intermediate flanged article is formed. Further, the toothed portion may be reshaped or raised when the peripheral flange is squeezed and thickened. 
   According to the present teachings, the peripheral flange of the intermediate flanged article may preferably be thickened, to thereby form the flanged article having the thickened peripheral flange. Therefore, a relatively think blank material can be utilized to form the flanged article, even if a relatively thicker peripheral flange is required. Consequently, manufacturing costs for preparing the flanged article can be reduced. 
   Other objects, features and advantages of the present invention will be ready understood after reading the following detailed description together with the accompanying drawings and the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 (A) is a plan view of an intermediate recessed plate according to one representative embodiment of the present teachings; 
     FIG.  1 (B) is a cross-sectional view taken along line I(B)—I(B) in FIG.  1 (A); 
     FIG.  1 (C) is a partially enlarged view of FIG.  1 (B); 
     FIG.  2 (A) is a plan view of a recessed plate according to another representative embodiment of the present teachings; 
     FIG.  2 (B) is a cross-sectional view taken along line II(B)—II(B) in FIG.  2 (A); 
     FIG.  2 (C) is a partially enlarged view of FIG.  2 (B); 
     FIG.  3 (A) is a vertical, cross-sectional view of an apparatus for manufacturing the intermediate recessed plate, illustrating a condition in which a sheet material is disposed between upper and lower dies of the apparatus; 
     FIG.  3 (B) is a vertical, cross-sectional view of the apparatus, illustrating a condition in which the sheet material is press formed in order to form the intermediate recessed plate; 
     FIG.  4 (A) is a vertical, cross-sectional view of an apparatus for manufacturing the recessed plate, illustrating a condition in which the intermediate recessed plate is disposed between upper and lower dies of the apparatus; and 
     FIG.  4 (B) is a vertical, cross-sectional view of the apparatus, illustrating a condition in which the intermediate recessed plate is squeezed in order to form the recessed plate. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In one embodiment of the present teachings, an intermediate recessed plate is formed from a circular sheet material or sheet blank (e.g., a substantially flat material) by utilizing a shear press forming apparatus. For example, the sheet material (sheet blank) may be placed and clamped between upper and lower die assemblies of the press forming apparatus. Thereafter, a punch associated with an upper die or clamp ring of the upper die assembly is moved (e.g., lowered) toward a corresponding die opening defined within a lower die of the lower die assembly. As a result, the sheet material can be shear press formed or half die cut, to thereby form the intermediate recessed plate. 
   The intermediate recessed plate thus formed may have a dish-like shape and may comprise a central circular depressed body coupled to a peripheral flange. Preferably, the peripheral flange is integrally or continuously connected to the central body via an annular shear deformed connecting portion. Further, the peripheral flange and the central body may define a circular open cavity or recess. 
   Optionally, a pair of tooth forming edges may be circumferentially defined along the outer surface of the punch. In this case, a pair of toothed portions can be formed on an inner circular surface of the peripheral flange when the sheet blank is press formed in order to form the intermediate recessed plate. 
   The intermediate recessed plate thus formed may then be further processed by utilizing a squeezing apparatus, to thereby form a recessed plate. For example, the intermediate recessed plate may be clamped between upper and lower die assemblies of the squeezing apparatus. Thereafter, the upper die assembly may be moved (e.g., lowered) toward the lower die assembly, so that the intermediate recessed plate is pushed into a die opening defined within the lower die assembly. As a result, the peripheral flange of the intermediate recessed plate will be radially inwardly squeezed or compressed therein and will thicken due to plastic deformation. Thus, it is possible to produce the recessed plate having a thickened peripheral flange that is thicker than the peripheral flange of the intermediate recessed plate. 
   In each of the embodiments described above and below, the sheet material or sheet blank, which may preferably be a substantially flat material, preferably comprises a metal material. More preferably, the sheet material is substantially or entirely a metal material. In this case, the metal material is manipulated according to known cold press forming techniques. A preferred metal material for use with the present teachings is steel. 
   In another embodiment of the present teachings, apparatus for manufacturing a flanged article that comprises a central depressed body and a peripheral flange are also taught. For example, means (e.g., a press forming apparatus) may be provided for press forming a substantially flat material in order to form an intermediate flanged article that comprises a central depressed body and a peripheral flange. In addition, means (e.g., a squeezing apparatus) may be provided for circumferentially squeezing the peripheral flange of the intermediate flanged article. As a result, the peripheral flange will be thickened as a result of plastic flow caused by plastic deformation, such that the thickness of the peripheral flange will be thicker than the substantially flat material. 
   In another embodiment, means (e.g., a clamp) may be provided for clamping the peripheral flange of the intermediate flanged article between an upper die and a piston movably received within a lower die opening of the squeezing apparatus. Preferably, at least a portion of the peripheral flange extends outwardly from the upper die in the clamped state. Further, means (e.g., pressure pins) may be provided for pushing the upper die and the piston into the lower die opening together with the intermediate flanged article clamped therebetween. Optionally, a punch may clamp the central body of the intermediate flanged article between the punch and the piston. 
   In another embodiment, means (e.g., a punch having tooth forming edges) may be provided for forming a toothed portion on an inner surface of the peripheral flange. In addition or in the alternative, means (e.g., a tapered or chamfered guide surface) may be provided for reshaping or raising the toothed portion. In this case, the length of the toothed portion defined on the inner surface of the peripheral flange can be increased during the squeezing operation. 
   In another embodiment of the present teachings, apparatus are taught for manufacturing a flanged article that comprises a central depressed body and a peripheral flange. Such apparatus may include means (e.g., a clamp) for clamping a peripheral flange of an intermediate flanged article between an upper die and a piston movably disposed within a lower die opening of a squeezing apparatus. Preferably, at least a portion (i.e., an extended portion) of the peripheral flange outwardly extends from the lower die opening in the clamped state. Further, a punch may clamp a central body of the intermediate flanged article between the punch and the piston. In addition, means (e.g., pressure pins) may be provided for pushing the upper die and the piston into the lower die opening together with the intermediate flanged article clamped therebetween. 
   In another embodiment, a chamfered or tapered guide surface may be defined around the upper periphery of the lower die opening. The chamfered or tapered guide surface may serve to inwardly squeeze the extended portion in order to thicken the peripheral flange. As a result, the peripheral flange will be thickened during the squeezing operation. 
   A detailed representative embodiment of the present teachings is shown in FIGS.  1 (A) to  4 (B), in which a circular dish-like toothed recessed plate  21  is exemplified in FIG.  2 (A) as a flanged article that can be prepared utilizing the present teachings. The recessed plate  21  is preferably formed by processing a previously formed, intermediate toothed recessed plate  20 , which is shown in FIG.  1 . Further, such a recessed plate  21  may be utilized, e.g., with a housing that defines a locking mechanism for a vehicle seat reclining device. 
   As shown in FIGS.  1 (A)- 1 (C), the intermediate recessed plate  20  as a primary product may preferably comprise a central circular depressed (offset) body  26  and a peripheral flange  22 . The peripheral flange  22  is integrally and continuously connected to the central body  26  via an annular shear deformed connecting portion  28 . Consequently, the inner surface of the peripheral flange  22  and top surface of the central body  26  define a circular open cavity or recess R 1 . In addition, two opposing toothed portions  24  are defined on an inner circular surface  22   a  of the peripheral flange  22 . As shown in FIG.  1 (C), the peripheral flange  22  may have substantially the same thickness as the central body  26 . 
   As shown in FIGS.  2 (A)- 2 (C), the recessed plate  21  as a secondary product (or final product) may preferably comprise a central circular depressed (offset) body  27  and a peripheral flange  23 . The peripheral flange  23  is integrally and continuously connected to the central body  27  via an annular shear deformed connecting portion  29 . As a result, the inner surface of the peripheral flange  23  and the top surface of the central body  27  define a circular open cavity or recess R 1 . 
   In addition, two opposing toothed portions  25  are defined on an inner circular surface  23   a  of the peripheral flange  23 . As shown in FIG.  2 (C), the peripheral flange  23  may have a thickness that is greater than the thickness of the central body  27 . Moreover, the diameter of the peripheral flange  23  may be smaller than the diameter of the peripheral flange  22  of the intermediate recessed plate  20 . Further, the thickness of the peripheral flange  23  may be thicker than the thickness of the peripheral flange  22 . 
   The intermediate recessed plate  20  may be formed by utilizing a press forming apparatus  1 . Thereafter, the intermediate recessed plate  20  is preferably processed by utilizing a squeezing apparatus  2 , to thereby form the recessed plate  21 . 
   As shown in FIGS.  3 (A) and  3 (B), the press forming apparatus  1  may include an upper die assembly that can move with respect to a lower die assembly. The upper die assembly may include an upper die or clamp ring  32  and a punch  30  that is movably disposed within the clamp ring  32 . Preferably, the punch  30  can move relative to the clamp ring  32  in the vertical direction (i.e., in the parallel direction), as shown in FIGS.  3 (A) and  3 (B). For example, the clamp ring  32  may be coupled to a plurality of hydraulically controlled pressure pins  34 , so as to be normally biased or forced downwardly. The punch  30  may be coupled to a hydraulic cylinder (not shown), so as to independently move toward and away from the lower die assembly. Further, the punch  30  is preferably profiled so as to have substantially the same shape as the recess R 1  that will be formed within the intermediate recessed plate  20 . In addition, tooth forming edges  31  may be disposed around the circumference of the punch  30 . The tooth forming edges  31  preferably correspond to opposing toothed portions  24  that will be formed along the inner circular surface  22   a  of the peripheral flange  22 . 
   The lower die assembly may include an annular lower die  36  having a die opening  37  that preferably corresponds to the profile of the punch  30 . The lower die assembly may further include an ejector plate  38  that is closely and movably received within the die opening  37 . The ejector plate  38  may be coupled to a plurality of hydraulically controlled pressure pins  39 , so as to be upwardly biased or forced. Preferably, the ejector plate  38  is designed so as to be normally coplanar with the lower die  36 . 
   As shown in FIGS.  4 (A) and  4 (B), the squeezing apparatus  2  also may include an upper die assembly that can move with respect to a lower die assembly. The upper die assembly may include an upper die or clamp ring  42  and a punch  40  that is movably disposed within the clamp ring  42 . Preferably, the punch  40  can move with respect to the clamp ring  42  in the vertical direction (i.e., in the parallel direction), as shown in FIGS.  4 (A) and  4 (B). The clamp ring  42  may be coupled to a plurality of hydraulically controlled pressure pins  44 , so as to be downwardly biased. Also, the clamp ring  42  may include a lower leading end portion  42   a , which portion  42   a  preferably has substantially the same diameter as the peripheral flange  23  of the recessed plate  21 . The punch  40  may be coupled to a hydraulic cylinder (not shown), so as to be normally biased or forced downwardly. 
   Still referring to FIGS.  4 (A) and  4 (B), the lower die assembly may include an annular-shaped lower die  52  having a die opening  54  that may preferably correspond to the profile of the clamp ring leading end portion  42   a . In addition, the upper periphery of the die opening  54  may be upwardly flared. As a result, an annular-shaped tapered (chamfered) guide surface  54   a  is defined around the upper periphery of the die opening  54 . The lower die assembly may further include a pad or piston  46  that is closely and movably received within the die opening  54 . The piston  46  may be coupled to a plurality of hydraulically controlled pressure pins  50 , so as to be upwardly biased or forced. The piston  46  also may include a depressed portion  48  that is designed to closely receive the central body  26  of the intermediate recessed plate  20 . 
   A representative method for manufacturing the recessed plate  21  using apparatuses  1  and  2  will now be described. As shown in FIG.  3 (A), a circular sheet material  10  is first disposed on the lower die  36  and the ejector plate  38  of the lower die assembly. Subsequently, the upper die assembly is lowered, so that the periphery of the sheet material  10  is clamped between the lower die  36  and the clamp ring  32  of the upper die assembly. 
   Although the sheet material  10  may be formed by a variety of known methods, the sheet material  10  is preferably formed by stamping out a metal plate having a desired thickness. As noted above, the metal plate may preferably be a steel plate (e.g., a boron doped carbon steel plate) and known techniques for cold press forming may be utilized with the present teachings. 
   As shown in FIG.  3 (B), the punch  30 , which is movably received within the clamp ring  32 , is then extended (e.g., lowered) toward the die opening  37  defined within the lower die  36 . As a result, the sheet material  10  is shear press formed or half die cut, to thereby form the intermediate recessed plate  20  as the primary product. Further, when the sheet material  10  is press formed, the toothed portions  24  are simultaneously formed along the inner circular surface  22   a  of the peripheral flange  22 , because tooth forming edges  31  are defined around the circumference of the punch  30 . 
   If the ejector plate  38  is upwardly biased or forced during the press forming step, the punch  30  will be lowered against the upward reactive force of the ejector plate  38 . Further, the punch  30  is preferably controlled in order to be lowered a predetermined distance, so that the connecting portion  28  will have the desired thickness. That is, persons skilled in the art can easily determine the predetermined distance for lowering the punch  30  in order to appropriate define the circular recess R 1 . 
   After completing the press forming operation, the punch  30  is retracted or withdrawn and then the upper die assembly is lifted or removed. As a result, the ejector plate  38  will be upwardly returned to its resting position due to the hydraulic force of the pressure pins  39 . Further, the intermediate recessed plate  20  will be ejected from the die opening  37  of the lower die  36 . 
   The intermediate recessed plate  20  thus formed comprises the central circular depressed body  26  and the peripheral flange  22  that are interconnected via the annular connecting portion  28 . At this time, the circular body  26  and the peripheral flange  22  will have substantially the same thickness as the sheet material  10 . The intermediate recessed plate  20  also includes the circular recess R 1  that is defined by the peripheral flange  22  and the central body  26 . In addition, two toothed portions  24  are formed around the inner circular surface  22   a  of the peripheral flange  22 . Further, as best shown in FIG.  1 (C), each of the toothed portions  24  may include a dull upper edge or shear drop  24   a  due to shearing. 
   The intermediate recessed plate  20  is then processed by utilizing the squeezing apparatus  2 . That is, as shown in FIG.  4 (A), the intermediate recessed plate  20  is placed or seated on the piston  46  of the lower die assembly such that the central body  26  is received within the depressed portion  48  of the piston  46 . Subsequently, the upper die assembly is moved (e.g., lowered) toward the lower die assembly, so that the peripheral flange  22  will be clamped between the piston  46  and the clamp ring end portion  42   a . In addition, the central body  26  will be clamped between the piston  46  and the punch  40 . As shown in FIG.  4 (A), the peripheral flange  22  preferably projects or extends radially outwardly from the piston  46  and the clamp ring end portion  42   a . In this case, an annular extending portion  22   b  will be defined around the peripheral flange  22 . 
   Thereafter, as shown in FIG.  4 (B), the upper die assembly is further moved (e.g., lowered) toward the lower die assembly. Thus, the clamp ring end portion  42   a  and the punch  40  will be pushed into the die opening  54  together with the piston  46  against the hydraulic force of the pressure pins  50 . At this time, the clamped intermediate recessed plate  20  is also pushed into the die opening  54  via the guide surface  54   a . Consequently, the annular extending portion  22   b  of the peripheral flange  22  will be radially inwardly squeezed or compressed by the guide surface  54   a  and the peripheral flange  22  will thicken as a result of plastic flow caused by plastic deformation. Thus, the recessed plate  21  having the thickened peripheral flange  23  is produced as the secondary product or final product. Further, because some of the compressed material may move into the toothed portions  24  due to plastic flow when the annular extending portion  22   a  is compressed, the upper shear drops  24   a  of the toothed portions  24  are effectively reshaped, repaired and/or raised. 
   If the clamp ring  42  is forced or biased hydraulically downward and the piston  46  is forced or biased hydraulically upward (i.e., in the opposite direction), the intermediate recessed plate  20  can be reliably clamped or supported during the squeezing operation. Therefore, the connecting portion  28  may be effectively prevented from bending or deforming during the squeezing operation. Further, the hydraulic force of the pressure pins  44 , which downwardly force or bias the clamp ring  42 , may preferably be set such that the clamp ring  42  can be returned or upwardly moved when the peripheral flange  22  is thickened. 
   After completing the squeezing operation, the upper die assembly is returned to its resting position (e.g., upwardly lifted), so that the clamp ring  42  and the punch  40  can be removed from the die opening  54 . At this time, the piston  46  is upwardly returned due to the hydraulic force of the pressure pins  50 , to thereby eject the recessed plate  21  from the die opening  54  of the lower die  52 . 
   The recessed plate  21  thus formed comprises the central circular depressed body  27  and the peripheral flange  23  that are interconnected via the annular connecting portion  29 . The circular body  27  has the same thickness as the sheet material  10 . However, the peripheral flange  23  has a thickness greater than the sheet material  10 . In other words, the peripheral flange  23  has a thickness greater than the peripheral flange  22  of the intermediate recessed plate  20 . Also, the recessed plate  21  includes the circular recess R 2  that is deeper than the recess R 1 . In addition, the toothed portions  25  are defined around the inner circular surface  23   a  of the peripheral flange  23  and the toothed portions  25  are longer than the toothed portions  24 . Further, as best shown in FIG.  2 (C), none of the toothed portions  25  preferably has a dull upper edge or a shear drop due to the reshaping that occurs during the squeezing operation. 
   Optionally, the recessed plate  21  thus formed may be further treated or processed (e.g., restriking or coining) by utilizing one or more additional processing machines (not shown), to thereby produce a finally finished product. However, the recessed plate  21  also can be used as a final product without additional processing. 
   According to the present methods, the recessed plate  21  having the peripheral flange  23  may preferably be formed by squeeze thickening the peripheral flange  22  of the intermediate recessed plate  20 . That is, it is possible to produce the recessed plate  21  having the thicker peripheral flange  23  from the thinner sheet material  10 . Therefore, it is not necessary to use a thicker sheet material  10  even if the recessed plate  21  requires a relatively thick peripheral flange  23 . As a result, it is possible to reduce manufacturing costs for the recessed plate  21  and to reduce the weight of the recessed plate  21 . 
   A representative example of the present invention has been described in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed in the foregoing detail description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe detailed representative examples of the invention. Moreover, the various features taught in this specification may be combined in ways that are not specifically enumerated in order to obtain additional useful embodiments of the present teachings.