EP0502746B1 - Production of rivet-nuts - Google Patents

Production of rivet-nuts Download PDF

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Publication number
EP0502746B1
EP0502746B1 EP19920301940 EP92301940A EP0502746B1 EP 0502746 B1 EP0502746 B1 EP 0502746B1 EP 19920301940 EP19920301940 EP 19920301940 EP 92301940 A EP92301940 A EP 92301940A EP 0502746 B1 EP0502746 B1 EP 0502746B1
Authority
EP
European Patent Office
Prior art keywords
rivet
mandrel
nut
thread
radial pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19920301940
Other languages
German (de)
French (fr)
Other versions
EP0502746A1 (en
Inventor
Stephen Graeme Richardson
Michael Lionel Osborne
Stephen John Morris
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Newfrey LLC
Original Assignee
Newfrey LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Newfrey LLC filed Critical Newfrey LLC
Publication of EP0502746A1 publication Critical patent/EP0502746A1/en
Application granted granted Critical
Publication of EP0502746B1 publication Critical patent/EP0502746B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/56—Making machine elements screw-threaded elements

Definitions

  • the present invention relates to the production of rivet-nuts, particularly using a technique of swaging on to a mandrel.
  • the rivet-nut is formed from a tubular body of uniform wall thickness, the nut being provided with an internal thread on one end portion of the body by the application of force applied in a radial direction towards the axis of the body so that material of the body wall is pressed into the thread of the inserted mandrel to form thread segments and the thus-produced rivet nut unscrewed from the mandrel.
  • a process is described in GB-A-1 462 429 and GB-A-1 439 811.
  • a process for the manufacture of a rivet nut by the insertion of a threaded mandrel into a tubular rivet body, the application of radial pressure to cause the material of an end portion of the tubular body to flow into the thread of the mandrel ans unscrewing the thus-formed rivet-nut is characterised in that, as the tubular body and threaded mandrel are inserted by a forward stroke of a forming operation into radial pressure applying means, the radial pressure applying means is rotated as the pressure is applied so that the newly-formed rivet-nut is caused to unscrew from the mandrel at least partly during the thread-forming operation. Preferably, half of the formed thread is unscrewed during the forward stroke.
  • the partial unscrewing of the rivet-nut in the forward, forming stroke of the swaging operation substantially improves the rate of operation of the rivet-nut manufacturing process.
  • the radial pressure applying means preferably comprises a ring of balls acting as a die to force the rivet body over the threaded mandrel during the forward stroke of a forming operation.
  • a rivet-nut formed by the process of the present invention is barely distinguishable from one formed in accordance with UK patent specification 1 439 811. It is, however, just possible to observe that the rotation of the pressure-applying means during thread formation produces a slight curvature of the thread segments formed in the rivet nut.
  • Figures 1-6 are schematic representations of a rivet nut producing apparatus illustrating the sequential operation of the process of the invention.
  • a rotating die 9 comprising a carrier having an outer sleeve 10 carrying a ring of balls 11 is rotated in the sense indicated by arrow A.
  • a threaded mandrel 12 carried by chuck 13 is picked up and is inserted through a tubular rivet body 14 (Fig.2) and is advanced in the direction indicated by arrow B until the rivet body 14 enters the rotating ring of balls 11 (Fig.3) which are operated to apply radial pressure to the rivet body 14.
  • the rotation of the die 9 not only forms a thread inside the rivet body 14, but also causes the body to unscrew partially from the threaded mandrel 12.
  • the threaded mandrel 12 is then withdrawn in the direction of arrow C as the die 9 continues to rotate in the direction of arrow A so that the unscrewing of rivet body 14 from threaded mandrel 12 continues to completion so that the rivet body released from the thread mandrel 12 can be ejected from the rotating die 9.
  • the process of the present invention is much quicker than the known process which requires the threaded rivet body to be fully unscrewed from the threaded mandrel after thread formation is completed.
  • the hitherto known process provides production rates of 10-15 items per minute, with the method of the present invention, production rates of more than 100 items per minute can easily be achieved.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Forging (AREA)

Description

  • The present invention relates to the production of rivet-nuts, particularly using a technique of swaging on to a mandrel.
  • It has been proposed to make rivet-nuts by a modification of a process used to manufacture blind rivets by crimping a tubular rivet body on to a mandrel by means of forces applied laterally to the axis of the mandrel inserted into the rivet body. By using a threaded mandrel, the rivet body can be removed by unscrewing to form a rivet nut.
  • The rivet-nut is formed from a tubular body of uniform wall thickness, the nut being provided with an internal thread on one end portion of the body by the application of force applied in a radial direction towards the axis of the body so that material of the body wall is pressed into the thread of the inserted mandrel to form thread segments and the thus-produced rivet nut unscrewed from the mandrel. Such a process is described in GB-A-1 462 429 and GB-A-1 439 811.
  • Whilst the rivet nut so produced is a perfectly acceptable product, the unscrewing operation is very slow and the productivity rate of the process is very low.
  • It is an object of the present invention to provide a method of making a rivet-nut by forming an internal threaded portion of the rivet body by application of radial force which has an enhanced productivity rate.
  • According to the present invention a process for the manufacture of a rivet nut by the insertion of a threaded mandrel into a tubular rivet body, the application of radial pressure to cause the material of an end portion of the tubular body to flow into the thread of the mandrel ans unscrewing the thus-formed rivet-nut is characterised in that, as the tubular body and threaded mandrel are inserted by a forward stroke of a forming operation into radial pressure applying means, the radial pressure applying means is rotated as the pressure is applied so that the newly-formed rivet-nut is caused to unscrew from the mandrel at least partly during the thread-forming operation. Preferably, half of the formed thread is unscrewed during the forward stroke. The partial unscrewing of the rivet-nut in the forward, forming stroke of the swaging operation substantially improves the rate of operation of the rivet-nut manufacturing process.
  • The radial pressure applying means preferably comprises a ring of balls acting as a die to force the rivet body over the threaded mandrel during the forward stroke of a forming operation. A rivet-nut formed by the process of the present invention is barely distinguishable from one formed in accordance with UK patent specification 1 439 811. It is, however, just possible to observe that the rotation of the pressure-applying means during thread formation produces a slight curvature of the thread segments formed in the rivet nut.
  • A preferred embodiment of the invention will be described in greater detail by way of example with reference to the accompanying drawings in which:
       Figures 1-6 are schematic representations of a rivet nut producing apparatus illustrating the sequential operation of the process of the invention.
  • In the drawings, (Figs 1-6) a rotating die 9 comprising a carrier having an outer sleeve 10 carrying a ring of balls 11 is rotated in the sense indicated by arrow A. A threaded mandrel 12 carried by chuck 13 is picked up and is inserted through a tubular rivet body 14 (Fig.2) and is advanced in the direction indicated by arrow B until the rivet body 14 enters the rotating ring of balls 11 (Fig.3) which are operated to apply radial pressure to the rivet body 14.
  • As the tubular rivet body 14 is engaged by the radially-pressing balls 11 threads are formed on the inner surface of the rivet body 14 by the pressure exerted by the ring of balls on the advancing rivet body 14 until the threaded mandrel 12 reaches the limit of its travel and ceases to move towards the rotating die (Fig.4).
  • The rotation of the die 9 not only forms a thread inside the rivet body 14, but also causes the body to unscrew partially from the threaded mandrel 12. The threaded mandrel 12 is then withdrawn in the direction of arrow C as the die 9 continues to rotate in the direction of arrow A so that the unscrewing of rivet body 14 from threaded mandrel 12 continues to completion so that the rivet body released from the thread mandrel 12 can be ejected from the rotating die 9.
  • Because of the partial unscrewing of the rivet body from the threaded mandrel during thread formation, the process of the present invention is much quicker than the known process which requires the threaded rivet body to be fully unscrewed from the threaded mandrel after thread formation is completed. Whereas the hitherto known process provides production rates of 10-15 items per minute, with the method of the present invention, production rates of more than 100 items per minute can easily be achieved.

Claims (3)

  1. A process for the manufacture of a rivet nut by the insertion of a threaded mandrel (12) into a tubular rivet body (14), the application of radial pressure to cause the material of an end portion of the tubular body (14) to flow into the thread of the mandrel (12) and unscrewing the thus-formed rivet-nut characterised in that, as the tubular body (14) and threaded mandrel (12) are inserted by a forward stroke of a forming operation into radial pressure applying means (11), the radial pressure applying means (11) is rotated as the pressure is applied so that the newly-formed rivet-nut is caused to unscrew from the mandrel (12) at least partly during the thread-forming operation.
  2. A process according to claim 1, wherein at least half of the formed thread is unscrewed during the forward stroke.
  3. A process according to claim 1 or 2, wherein the radial pressure applying means comprises a ring of balls (11) acting as a die to force the tubular body (14) over the threaded mandrel (12) during the forward stroke of a forming operation.
EP19920301940 1991-03-06 1992-03-06 Production of rivet-nuts Expired - Lifetime EP0502746B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9104706 1991-03-06
GB919104706A GB9104706D0 (en) 1991-03-06 1991-03-06 Production of rivet-nuts

Publications (2)

Publication Number Publication Date
EP0502746A1 EP0502746A1 (en) 1992-09-09
EP0502746B1 true EP0502746B1 (en) 1994-10-19

Family

ID=10691073

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920301940 Expired - Lifetime EP0502746B1 (en) 1991-03-06 1992-03-06 Production of rivet-nuts

Country Status (3)

Country Link
EP (1) EP0502746B1 (en)
DE (1) DE69200529T2 (en)
GB (1) GB9104706D0 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2390047B (en) * 2002-06-28 2005-05-11 Textron Fastening Syst Ltd Split die groove maker
US9475109B2 (en) 2013-12-31 2016-10-25 Simpson Strong-Tie Company, Inc. Method of manufacturing a hollow externally threaded fastener

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1187602A (en) * 1950-06-16 1959-09-14 Internal or external threading process for tubes
US2862215A (en) * 1954-07-13 1958-12-02 Red Lion Cabinet Company Machine for forming threads within a metallic tube by swaging
US2976549A (en) * 1956-03-12 1961-03-28 Neo Products Corp Hollow metal article and method and apparatus for forming same
US3089161A (en) * 1960-02-11 1963-05-14 Edwin P Sundholm Method of forming an internally threaded, gasket-retaining cap
GB1462429A (en) * 1974-04-04 1977-01-26 Vyzk Ustav Mech Apparatus for the shaping of hollow metal bodies
NL7901892A (en) * 1979-03-08 1980-09-10 Erico Europa Forming self locking screw thread in tube - by cold forging on hollow former, unscrewing it after reducing temp. or internal pressure

Also Published As

Publication number Publication date
EP0502746A1 (en) 1992-09-09
GB9104706D0 (en) 1991-04-17
DE69200529T2 (en) 1995-02-23
DE69200529D1 (en) 1994-11-24

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