Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B37/00—Nuts or like thread-engaging members
  • F16B37/02—Nuts or like thread-engaging members made of thin sheet material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
  • B21D22/20—Deep-drawing
  • B21D22/206—Deep-drawing articles from a strip in several steps, the articles being coherent with the strip during the operation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
  • B21D22/20—Deep-drawing
  • B21D22/24—Deep-drawing involving two drawing operations having effects in opposite directions with respect to the blank
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/24—Making other particular articles nuts or like thread-engaging members

Definitions

• the present invention relates to a method of fabricating a clamping nut through drawing of a metallic sheet.
• a conventional clamping nut 50 used for assembling an electronic product such as a
• PDP Plasma Display Panel
• LCD Liquid Crystal Display
• the clamping nut 50 includes a cylindrical nut body 51, and a flange part 51 at the base of the nut body 51, and threads 53 are formed through the clamping nut 50.
• a groove 54 is formed between the nut body 51 and the flange part 52.
• the clamping nut 50 is inserted in a mounting hole formed in the metallic substrate or the housing, and then the groove 54 is engaged with the circumferential edge of the mounting hole. In this manner, the clamping cut 50 is mounted on the substrate or in the housing.
• Such a clamping nut 50 is fabricated through cutting or hot forging as disclosed in Patent Document 1 or Patent Document 2.
• a clinching nut and a method of fabricating the same have been proposed as disclosed in Patent Document 3.
• the clinching nut is fabricated by forming a flange part and a hollow-cylindrical part initiating from the flange part through drawing of a metallic sheet, piercing the bottom of the hollow- cylindrical part, and forming threads through the inner surface of the hollow- cylindrical part.
• Patent Document 1 Japanese Un-examined Patent Publication No. 2002-227817
• Patent Document 2 Japanese Un-examined Patent Publication No. 2000-326047
• Patent Document 3 Japanese Un-examined Patent Publication No. 2006-297455
• the present invention is to provide a method of fabricating a clamping nut, which can be performed with low costs without inducing loss of material.
• a method of fabricating a clamping nut including the steps of: drawing a metallic sheet, thereby forming a hollow-cylindrical half- finished work having a flange part, an outer hollow- cylindrical part, and a closed end; reverse-drawing the closed end of the hollow- cylindrical half- finished work, thereby forming an inner hollow-cylindrical part with a closed end, the hollow-cylindrical part projecting inward from the closed end; and performing a process for increasing the thickness of the inner hollow-cylindrical part, thereby forming a clamping part, simultaneously piercing the closed end of the inner hollow-cylindrical part.
• one or more projections projecting outward from the outer periphery of the outer hollow-cylindrical part are formed at an area adjacent to the open end of the outer hollow-cylindrical part opposite to the closed end, and one or more fastening holes are formed between the projections and the flange part, so that the inner and outer sides of the outer hollow-cylindrical part communicate with each other.
• threads may be formed through the clamping part through tapping.
• the reverse-drawing is preferably performed as free-drawing for forming the inner hollow-cylindrical part in a state in which the inside of the outer hollow-cylindrical part is not restrained.
• the process for increasing the thickness of the inner hollow-cylindrical part may be preferably performed through multi-stage press-drawing, the multi-stage press-drawing including the steps of: setting the half- finished work on a die in a state in which the flange part is positioned upward, the die including a setting bore receiving the outer hollow-cylindrical part, and a guide protrusion projecting from the bottom of the setting bore and having an outer diameter smaller than the inner diameter of the inner hollow-cylindrical part; and lowering a press-drawing punch so that the tip end of the press-drawing punch penetrates between the outer hollow-cylindrical part and the inner hollow-cylindrical part, thereby reducing the surface area of the outer surface of the inner hollow-cylindrical part, wherein a volume of the material of the inner hollow- cylindrical part corresponding to the reduced surface area is converted into the thickness of the inner hollow-cylindrical part, thereby increasing the thickness of the inner hollow-cylindrical part
• the process for increasing the thickness of the inner hollow-cylindrical part may be performed through swaging, the swaging step including the steps of: setting the half-finished work on a die in a state in which the flange part is positioned upward, the die including a setting bore receiving the outer hollow-cylindrical part, and a guide protrusion projecting from the bottom of the setting bore and having an outer diameter smaller than the inner diameter of the inner hollow-cylindrical part; lowering a swaging punch, the swaging punch being received in a hollow-cylindrical sleeve, so that the sleeve is freely slidable in relation to the swaging punch, and the sleeve having an inner diameter larger than the outer diameter of the inner hollow-cylindrical part; rendering the tip end of the swaging punch to come into contact with the closed end of the inner hollow-cylindrical part in a state in which the sleeve is
• the slitting may include the steps of: setting the half-finished work on a slitting die in a state in which the flange part is positioned upward, the slitting die having a setting bore receiving the outer hollow-cylindrical part, and one or more slitting edges formed at the inlet area of the setting bore, the slitting edges being formed with radial recesses at a predetermined angle; and lowering a slitting punch having a shape corresponding to the slitting die.
• a clamping nut is fabricated through the steps of: drawing a metallic sheet, thereby forming a hollow-cylindrical half- finished work having a flange part, an outer hollow-cylindrical part, and a closed end; reverse- drawing the closed end of the hollow-cylindrical half- finished work, thereby forming an inner hollow-cylindrical part with a closed end, the hollow-cylindrical part projecting inward from the closed end; and performing a process for increasing the thickness of the inner hollow-cylindrical part, thereby forming a clamping part, simultaneously piercing the closed end of the inner hollow-cylindrical part.
• the material of the clamping nut is not lost, and no step for cutting is added, whereby it is possible to substantially reduce the manufacturing costs.
• the clamping nut can be fabricated from an inexpensive rolled steel sheet, it is possible to save material costs. If such a clamping nut is fabricated according to the present invention, it is possible to reduce the manufacturing costs by 30 to 40% as compared to the case in which such a clamping nut is fabricated through cutting or the like, as in the prior art.
• clamping nuts it is possible to automatically and continuously fabricate clamping nuts with a transfer press or the like. As a result, clamping nuts can be efficiently mass-produced. Further more, if the clamping nuts are fabricated according to the present invention, the surface characteristics and conditions of the clamping nuts are very good as compared to those fabricated through forging as in the prior art, and it is not necessary to fabricate the clamping nuts in a poor environment.
• the present invention it is possible to increase the thickness of the inner hollow-cylindrical part through a process for increasing the thickness. Therefore, threads can be formed through the inner hollow-cylindrical part with an increased thickness, and the strength of the clamping part can be enhanced. Furthermore, when mounting an electronic component or substrate, the electronic component or substrate comes into contact with the bottom (open end) of the outer hollow-cylindrical part, a sufficient contact area can be secured, and the electronic component or substrate can be stably mounted. In addition, because surface pressure is increased, it is possible to prevent the fracture of the electronic component or substrate.
• one or more projections projecting outward from the outer periphery of the outer hollow-cylindrical part are formed at an area adjacent to the open end of the outer hollow-cylindrical part opposite to the closed end, and one or more fastening holes are formed between the projections and the flange part, so that the inner and outer sides of the outer hollow- cylindrical part communicate with each other.
• the projections are inserted into the mounting hole, thereby applying high compressive force to the circumferential surface of the mounting hole, and the material of the object to be joined fills the fastening holes, it is possible to rigidly and fixedly join the object and the clamping nut.
• the process for increasing the thickness of the inner hollow-cylindrical part may be performed by multi-stage press- drawing, the multi-stage press-drawing including the steps of: setting the half-finished work on a die in a state in which the flange part is positioned upward, the die including a setting bore receiving the outer hollow-cylindrical part, and a guide protrusion projecting from the bottom of the setting bore and having an outer diameter smaller than the inner diameter of the inner hollow-cylindrical part; and lowering a press- drawing punch so that the tip end of the press-drawing punch penetrates between the outer hollow-cylindrical part and the inner hollow-cylindrical part, thereby reducing the surface area of the outer surface of the inner hollow-cylindrical part, wherein a volume of the material of the inner hollow-cylindrical part corresponding to the reduced surface area is converted into the thickness of the inner hollow-cylindrical part, thereby increasing the thickness of the
• the process for increasing the thickness of the inner hollow-cylindrical part may be performed by swaging, the swaging including the steps of: setting the half- finished work on a die in a state in which the flange part is positioned upward, the die including a setting bore receiving the outer hollow-cylindrical part, and a guide protrusion projecting from the bottom of the setting bore and having an outer diameter smaller than the inner diameter of the inner hollow-cylindrical part; lowering a swaging punch, the swaging punch being received in a hollow-cylindrical sleeve, so that the sleeve is freely slidable in relation to the swaging punch, and the sleeve having an inner diameter larger than the outer diameter of the inner hollow-cylindrical part; rendering the tip end of the swaging punch to come into contact with the closed end of the inner hollow-cylindrical part in a state in
• the slitting may include the steps of: setting the half-finished work on a slitting die in a state in which the flange part is positioned upward, the slitting die having a setting bore receiving the outer hollow-cylindrical part, and one or more slitting edges formed at the inlet area of the setting bore, the slitting edges being formed with radial recesses at a predetermined angle; and lowering a slitting punch having a shape corresponding to the slitting die.
• FIG. 1 shows a perspective view of a clamping nut which is fabricated according the inventive method of fabricating a clamping nut
• FIG. 2 shows a vertical cross-sectional view of FIG. 1
• FIG. 3 shows a horizontal cross-sectional view of FIG. 1
• FIG. 4 shows a bottom view of FIG. 1
• FIG. 5 shows steps of the inventive method of fabricating a clamping nut
• FIGs. 6A and 6B show views for describing the sub-steps of a reverse-drawing step
• FIG. 7 is a view for describing a multi-stage press forming step
• FIG. 8 shows a view for describing the sub-steps of the swaging step
• FIG. 9 shows a view for describing a slitting step
• FIG. 10 shows a view for describing a method of coupling a clamping nut to an object to be mounted
• FIG. 11 shows a cross-sectional view of a conventional clamping nut.
• FIG. 1 shows a perspective view of a clamping nut which is fabricated according the inventive method of fabricating a clamping nut.
• FIG. 2 shows a vertical cross-sectional view of FIG. 1
• FIG. 3 shows a horizontal cross-sectional view of FIG. 1
• FIG. 4 shows a bottom view of FIG. 1.
• the clamping nut 1 includes an outer hollow- cylindrical part 2, a flange part 3, an inner hollow-cylindrical part 4 (clamping part), a plurality of fastening holes 5, and a plurality of projections 6.
• the outer hollow-cylindrical part 2 is formed in a shape of a hollow cylinder with one closed end.
• the horizontal cross-sectional shape of the outer hollow-cylindrical part 2 is circular.
• the flange part 3 extends from the open end of the outer hollow- cylindrical part 2 perpendicular to the axial direction of the outer hollow-cylindrical part 2. As shown in FIGs. 3 and 4, the flange part 3 takes a hexagonal shape in the present embodiment.
• the inner hollow-cylindrical part 4 is formed in a hollow-cylindrical shape, and extends from the closed end 2a of the outer hollow-cylindrical part 2 into the inside of the outer hollow-cylindrical part 2 coaxial to the outer hollow-cylindrical part 2.
• the inner hollow-cylindrical part 4 serves as a clamping part.
• the inner circumferential surface of the inner hollow-cylindrical part 4 is formed with threads 7.
• the projections 6 are formed around an area adjacent to the open end of the outer hollow-cylindrical part 2, wherein each of the projections 6 projects outward from the outer circumferential surface of the outer hollow-cylindrical part 2 at a predetermined angle. In addition, the projections 6 project inward from the outer hollow-cylindrical part 2 as well.
• the fastening holes 5 are formed between the flange part 6 and the projections 6 of the outer hollow-cylindrical part 2, so that the inside and outside of the outer hollow-cylindrical part 2 communicate with each other.
• FIG. 50 the inventive method of fabricating the clamping nut 1 will be described.
• FIG. 5 shows steps of the inventive method of fabricating a clamping nut.
• a blanking step a blank of a rolled steel sheet is extracted in such a manner that a circular opening is formed in the steel sheet, thereby forming a circular blank.
• the circular blank is transferred to a first drawing step.
• the circular blank is set on a drawing die with a drawing opening, a circular recess being formed around the top of the drawing opening, and a substantially cylindrical punch is lowered from the upper side so as to plastically deform the circular blank, thereby forming a cylinder shape with a closed end.
• the first drawing step is terminated, the firstly drawn hollow-cylindrical half- finished work with a closed end is transferred to second and third drawing steps in sequence, so that the firstly drawn hollow-cylindrical half-finished work is gradually drawn more deeply, thereby forming a thirdly drawn hollow-cylindrical half- finished work with a closed end.
• the principal parameters of each of the first to third drawing steps are the radius of a punch and an opening of a die, a distance between the punch and the die, drawing rate, punch force, die cushion pressure, lubrication, etc.
• FIGs. 6A and 6B show views for describing the sub-steps of a reverse-drawing step.
• the reverse-drawing step consists of a free-drawing step (FIG. 6A) and a net-shape forming step (FIG. 6B).
• the die 19 used in the free-drawing step has a substantially cylindrical setting protrusion 19a as shown in FIG. 6 A.
• the diameter of the setting protrusion 19a is somewhat smaller than the inner diameter of the external hollow- cylindrical part 2.
• the punch 20 used in the free-drawing step has a cylindrical shape as shown in FIG. 6A.
• the hollow-cylindrical half-finished work with a closed end is set on the die 19 in such a manner that the flange part 3 is positioned downward, and then the punch 20 is lowered so that the punch 20 comes into contact with and plastically deforms the closed end 2a of the hollow-cylindrical half- finished work, thereby forming an inner hollow-cylindrical part 4.
• the free-drawing step is performed in a state in which the inner and outer sides of the outer hollow-cylindrical part 2 are not restrained.
• the principal process parameters of the free-drawing step are the shape of the punch
• the net-shape forming die 21 used in the net-shape forming step takes a cylindrical shape, and a groove serving as a net-shaping recess 21a is coaxially formed on the top of the net- shape forming die 21.
• the outer diameter of the net-shape forming die 21 is somewhat smaller than the inner diameter of the outer hollow-cylindrical part 2.
• the net-shape forming die 22 used in the net-shape forming step has a net- shape forming protrusion 22a in a cylindrical shape.
• the half-finished work roughly formed with the inner hollow-cylindrical part 4 is set on the net-shape forming die 21 in such a manner that the flange part 3 is positioned downward, and the net-shape forming punch 22 is lowered and plastically deforms the roughly formed inner hollow-cylindrical part 4 so that the space between the net-shape forming recess 21a and the net-shape forming protrusion 22a is filled with the material of the half -finished work, thereby forming the net- shape of the inner cylinder- shape part 4.
• the reverse-drawing step for forming the inner hollow- cylindrical part 4 is divided into the free-drawing step and the net-shape forming step, and the inner hollow-cylindrical part 4 is roughly formed through free-drawing without restraining the inner and outer sides of the outer hollow-cylindrical part 2.
• the free-drawing step in the present embodiment is performed without restraining both the inner and outer sides of the outer hollow-cylindrical part 2, it is possible to prevent the thickness of the inner hollow-cylindrical part 4 from being thinned, even if the inner hollow-cylindrical part 4 is roughly formed in the state in which only the inner side of the outer hollow-cylindrical part 4 is not restrained.
• FIG. 7 is a view for describing a multi-stage press-drawing step.
• the die 23 used in the multi-stage press-drawing step is formed with a cylindrical setting bore 23a as shown in FIG. 7.
• the outer hollow-cylindrical part 2 is received in the setting bore 23a.
• a guide punch 23b is installed within the setting bore 23a.
• the guide punch 23b has a guide protrusion 23d projecting from a substantially cylindrical base member 23c.
• the cross-section of the guide protrusion 23d is circular and coaxial to the setting bore 23a.
• the press-drawing punch 24 used in the multi-stage press-drawing step has a cylindrical shape, and a drawing recess 24a is formed on the tip end 24b of the press- drawing punch 24.
• the cross-sectional shape of the drawing recess 24a is circular and coaxial to the periphery of the press-drawing punch 24.
• the inner diameter of the drawing recess 24a is smaller than the outer diameter of the inner hollow-cylindrical part 4.
• the outer hollow-cylindrical part 2 is inserted to the drawing recess 24a in the state in which the flange part 3 is positioned upward, whereby the half- finished work is set on the die 23. From this state, if the press- drawing punch 24 is lowered, the tip end 24b is inserted between the outer hollow- cylindrical part 2 and the inner hollow-cylindrical part 4. As described above, because the inner diameter of the drawing recess 24a is smaller than the outer diameter of the inner hollow-cylindrical part 24, the inner hollow-cylindrical part 4 is narrowed by the drawing recess 24a.
• the outer surface of the inner hollow-cylindrical part 4 is reduced, and the volume corresponding to the reduced amount of the outer surface plastically flows and is converted to the thickness of the inner hollow- cylindrical part 4, thereby increasing the thickness of the inner hollow-cylindrical part 4.
• the inner side of the inner hollow-cylindrical part 4 is restrained in shape by the guide protrusion 23d, the shape of the inner side of the inner hollow- cylindrical part 4 is maintained as it is.
• the inner hollow- cylindrical part 4 is subjected to the axial compressive force of the press-drawing punch 24, the height of the hollow-cylindrical part 4 is compressed to the height of the guide protrusion.
• the inner diameter of the hollow-cylindrical part 4 becomes substantially equal to the inner diameter of the drawing recess 24a, and the inner diameter of the inner hollow-cylindrical part 4 becomes substantially equal to the outer diameter of the guide protrusion 24a.
• the thickness of the inner hollow-cylindrical part 4 is increased by about 3% by performing multi-stage press-drawing one time.
• the multi-stage press-drawing is performed three to four times by using a press- drawing punch 24a having a drawing recess 24a with a smaller inner diameter, and a guide punch 23b having a guide protrusion 23d with a smaller outer diameter, it is possible to increase the thickness of the inner hollow-cylindrical part 4 by about 10%. If the multi-stage drawing step is terminated, the half-finished work is transferred to a piercing step.
• the half-finished work is set on a piercing die (not shown), and the punch is lowered to pierce the closed end 4a of the inner hollow-cylindrical part 4 (FIG. 5).
• the half-finished work is transferred to a swaging step.
• FIG. 8 shows a view for describing the sub-steps of the swaging step. As shown in
• the die 26 used in the swaging step is formed with a cylindrical setting bore 26a.
• the outer hollow-cylindrical part 2 is received in the setting bore 26a.
• a guide punch 27 is installed within the setting bore 26a.
• the guide punch 27a has a guide protrusion 27b protruding from the top of a substantially cylindrical base member 27a.
• the cross-sectional shape of the guide protrusion 27b is circular and coaxial to the setting bore 26a.
• the outer diameter of the guide protrusion 27b is somewhat smaller than the outer diameter of the inner hollow-cylindrical part 4.
• the punch used in the swaging step includes a hollow-cylindrical sleeve 28, and a cylindrical swaging punch 29 received in the sleeve 28.
• the sleeve 28 is freely slidable in relation to the swaging punch 29.
• the outer diameter of the swaging punch 29 is somewhat smaller than the inner diameter of the sleeve 28.
• At least one spring 30 is mounted on the top of the sleeve.
• the inner diameter of the sleeve 28 is larger than the inner hollow-cylindrical part 4, and thus a clearance c is formed between them as shown in FIG. 8.
• the half-finished work is set on the die 26 by inserting the outer hollow-cylindrical part 2 into the setting bore 26a in the state in which the flange part 3 is positioned upward.
• the sleeve 28 and the swaging punch 29 are lowered. If the sleeve 28 is inserted between the outer hollow-cylindrical part 2 and the inner hollow- cylindrical part 4, and the tip end of the sleeve 28 comes into contact with the closed end 2a of the outer hollow-cylindrical part 2, the spring 30 is compressed, and the lowering of the sleeve 28 is stopped. In addition, if the swaging punch 29 is lowered, the inner hollow-cylindrical part 4 is compressed.
• the material of the inner hollow-cylindrical part 2 cannot plastically flow inward.
• the swaging punch 29 is lowered, the material of the inner hollow- cylindrical part 2 outwardly plastically flows. Consequently, the material fills the space between the inside of the sleeve 28 and the outside of the swaging punch 29, thereby increasing the thickness of the inner hollow-cylindrical part 4.
• the thickness of the inner hollow-cylindrical part 4 prior to performing the swaging is t
• the thickness of the inner hollow-cylindrical part 4 is increased to t+c through the swaging, wherein c indicates the increased thickness.
• the thickness of the inner hollow-cylindrical part 4 is increased by about 10 to 30%.
• the principal process parameters of the swaging step are the punching force of the swaging punch 29, the ratio of the thickness to the length of the inner hollow- cylindrical part 4, lubrication, etc. If the swaging step is terminated, the half- finished work is transferred to a slitting step.
• FIG. 9 shows a view for describing a slitting step.
• the slitting die used in the slitting step is formed with a cylindrical setting bore 32a, as shown in FIG. 9.
• the setting bore 32a is somewhat larger than the outer periphery of the outer hollow-cylindrical part 2.
• the outer hollow-cylindrical part 2 is received within the setting bore 32a.
• a plurality of slitting edges 32b are formed at the inlet area of the setting bore 32a by a plurality of radial recesses.
• the slitting punch 33 used in the slitting step is cylindrical.
• the outer diameter of the slitting punch 33 is somewhat smaller than the inner diameter of the outer hollow- cylindrical part 2.
• the slitting punch 33 has a plurality of slitting projections 33a projecting from the periphery of the slitting punch 33 at the positions corresponding to the positions of the slitting edges 32b, wherein the shape of the slitting projections 33a corresponds to that of the slitting edges 33b in shape.
• the slitting projections 33a project from the periphery of the slitting punch 33 at a predetermined angle. If the slitting punch 33 is lowered, the slitting punches 33a are engaged with the slitting edges 33b.
• the half-finished work is set on the slitting die 32 by inserting the outer hollow-cylindrical part 2 into the setting bore 32a in the state in which the flange part is positioned upward. From this state, if the slitting punch 33 is lowered, the slitting projections 33a are engaged with the slitting edges 32b, thereby shearing the area adjacent to the open end of the outer hollow-cylindrical part 4, thereby forming fasting openings 5 in the area as shown in FIGs. 1 and 2. At the same time, the sheared area is coined by the slitting projections 33a, thereby forming the projections 6.
• the principal process parameters of the slitting step are the distance between the slitting die 32 and the slitting punch 33, the angle of cutting edge of the slitting projections 33a, and the slitting force. If the slitting step is terminated, the half-finished work is transferred to a trimming step.
• the unnecessary portion of the flange part 3 of the half-finished work is trimmed into a non-circular shape, such as a rectangular, hexagonal, octagonal, or saw tooth shape.
• the flange part 3 is formed in a hexagonal shape as shown in FIGs. 1 to 4.
• the steps of blanking to trimming are performed by a transfer press (A press apparatus performing each of the above-mentioned steps by transferring a half-finished work to individual dies with a transfer unit).
• the steps of blanking to trimming can be automatically and continuously performed by a transfer press, thereby efficiently producing clamping nuts.
• a half-finished work may be sequentially transferred from the blanking step to the trimming step (This may be performed by a press apparatus which has a plurality of molds arranged at a predetermined interval and sequentially transferred within a die, so that individual steps are sequentially performed while transferring a half- finished work by the above- mentioned interval for each step, wherein the press apparatus is also called as progressive press).
• the half-finished work is formed with threads within the inner hollow-cylindrical part 4, which is a clamping part, in a tapping step.
• the tapping step is formed by a rolling tap or a machine tap.
• FIG. 10 shows a view for describing a method of joining a clamping nut to an object to be mounted.
• the clamping nut 1 is joined to an object 40 in a press riveting step.
• the object 40 is formed with a mounting hole 40a which is somewhat larger than the outer periphery of the outer hollow-cylindrical part 2.
• the insertion die 35 used in the press riveting step is formed with a setting bore 35a which is somewhat larger than the outer periphery of the outer hollow-cylindrical part 2, so that the setting bore 35a receives the outer hollow-cylindrical part 2.
• a substantially cylindrical forming punch 36 is arranged above the setting bore 35 a.
• the object 40 is set on the insertion die 35 in such a manner that the mounting hole
• the outer hollow-cylindrical part 2 is inserted into the mounting hole 40a and the setting bore 35a, thereby setting the clamping nut 1.
• the press forming punch 36 is lowered, the projections 6 are plastically deformed and penetrate into the mounting hole 40a, and the flange part 3 is also inserted into the object 40.
• the material of the object 40 plastically flows into the fastening holes 5 by the volume of the flange part 3 press-fitted in the object 40, thereby filling the fastening holes 5.
• the projections 6 are inserted into the mounting hole 40a in this manner, and strong compressive force is applied to the surface of the mounting hole 40a, whereby the clamping nut is fixedly joined to the object 40.
• the material of the object 40 fills the fastening holes 5, the object 40 and the clamping nut 1 are more rigidly and fixedly joined to each other.
• the flange part 3 is formed in a non-circular shape, such as a rectangular, hexagonal, octagonal, or saw tooth shape, and inserted into the object 40, the clamping the rotation of the clamping nut 1 is suppressed when a screw is engaged the clamping nut 1, thereby preventing the fracture of joint between the clamping nut 1 and the object 40.
• the principal process parameters of the press-riveting step are the distance between the mounting hole 40a of the object 40 and the clamping nut 1, the thickness of the projections 6, and the width and height of the fastening holes 5.
• the threads 7 are formed in the clamping part, i.e. in the inner hollow-cylindrical part 4, in the tapping step described above, the tapping step may be omitted if the clamping nut is clamped by a tapping screw.
• the thickness of the area forming the clamping part in the inner hollow-cylindrical part is increased through multi-stage press-drawing and swaging
• the thickness of the inner hollow-cylindrical part 4 may be increased by using only one of the multi-stage press-drawing and the swaging as desired.
• multi-stage press-drawing is performed, then piercing is performed, and then swaging is performed
• the present invention is not limited to the order of these steps, and the order of the steps may be optionally determined.
• the material used for the inventive method of fabricating a clamping nut is not limited to a rolled steel sheet, and the inventive method is applicable to any type of metallic sheets, including a non-ferrous metal sheet, such as a copper sheet, a stainless steel plate, an aluminum sheet, etc.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Forging (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)

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• 2007
  • 2007-05-08 JP JP2007123382A patent/JP3998216B1/ja not_active Expired - Fee Related
• 2008
  • 2008-05-07 WO PCT/KR2008/002570 patent/WO2008136643A2/en active Application Filing
  • 2008-05-07 CN CN2008800236619A patent/CN101743075B/zh not_active Expired - Fee Related
  • 2008-05-08 TW TW97117062A patent/TW200920513A/zh not_active IP Right Cessation

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