EP0419436B1 - Method and device for tightening threaded joints - Google Patents

Method and device for tightening threaded joints Download PDF

Info

Publication number
EP0419436B1
EP0419436B1 EP19900850317 EP90850317A EP0419436B1 EP 0419436 B1 EP0419436 B1 EP 0419436B1 EP 19900850317 EP19900850317 EP 19900850317 EP 90850317 A EP90850317 A EP 90850317A EP 0419436 B1 EP0419436 B1 EP 0419436B1
Authority
EP
European Patent Office
Prior art keywords
torque
tool
power supply
joint
predetermined pretension
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
EP19900850317
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0419436A2 (en
EP0419436A3 (en
Inventor
Gunnar Christer Hansson
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.)
Atlas Copco Industrial Technique AB
Original Assignee
Atlas Copco Tools AB
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 Atlas Copco Tools AB filed Critical Atlas Copco Tools AB
Publication of EP0419436A2 publication Critical patent/EP0419436A2/en
Publication of EP0419436A3 publication Critical patent/EP0419436A3/en
Application granted granted Critical
Publication of EP0419436B1 publication Critical patent/EP0419436B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
    • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
    • B25B23/145—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
    • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
    • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
    • B25B23/147—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers

Definitions

  • This invention relates to a method and a device for tightening threaded joints to a predetermined pretension level, cf. for example EP-A-0 090 188.
  • the invention relates to a method and a manually supported device for tightening threaded joints in an improved manner as regards ergonomics.
  • a problem concerned with hand held power nutrunners is the difficulty for the operator to adapt his muscle force to the rapidly changing reaction forces developed in the tool housing and handles. Specifically, there is a problem for the operator to be exposed to the tiring jerks occurring at the end of the tightening process when the delivered torque and, accordingly, the reaction torque is abruptly discontinued. The operators' ability to react is not at all as quick as the torque disappearance in the tool handles, which means that the operator himself unintentionally causes a jerk of the tool.
  • the invention provides a method for tightening threaded joints by means of a torque delivering tool including a power supply and comprising applying torque to a joint to be tightened until a predetermined pretension level in the joint is reached, whereafter torque delivery is ceased, whereby upon reaching the predetermined pretension level in the joint, the torque delivered to the joint by the tool is made to cease gradually by gradually decreasing the power supply to the tool.
  • the invention provides a device to carry out the method for tightening threaded joints, comprising a torque delivering power tool, a power supply means connecting said tool to a power source, and a control means coupled to said power supply means, whereby said control means is arranged to initiate shutting off of the power supply to said tool as said predetermined pretension level is reached and initiate a continued, gradually decreasing power supply to said tool as said predetermined pretension level is passed.
  • FIG 1 there is illustrated the relationship between the torque M delivered to the joint, the position D of the tool handle and time t for three different joints I, II, and III having different torque rates.
  • Joint I is the stiffest joint with a very steep torque rate and a short tightening process duration.
  • Joint II has a medium torque rate, whereas joint III has a low torque rate and a comparatively long tightening process duration.
  • the position D of the tool handle is illustrated as a function of the delivered torque M and of time during the tightening process.
  • the method and device according to the invention modifies the tightening process in such a way that the torque application on the threaded joint is extended in time past the point representing the predetermined pretension level.
  • the extended torque application over a time interval ⁇ t has a gradually decreasing characteristic, and as illustrated in Fig 2, torque is successively brought down to nill in a linear manner.
  • the torque decreasing rate dM/dt is adjustable so as to adapt the torque applicaton characteristics of the tool to the individual ability to react of each operator.
  • the extended torque application time ⁇ t should be adjustable within the interval 0.1 - 0.5 s for the pretension torque interval 15 - 150 Nm, and for higher pretension torque magnitudes ⁇ t should be further extended.
  • a suitable torque decreasing rate dM/dt should be 50-300 Nm/s.
  • the device illustrated in Fig 3 comprises an electrically powered tightening tool 10-comprising a brushless AC-motor, a power supply means 11 and a control unit 12.
  • the power supply means 11 comprises an inverter which is fed with DC power from a DC power source 14 and which delivers AC power of variable frequency and voltage amplitude to the tool 10.
  • a power detecting means 15 is provided between the DC power source 14 and the power supply means 11 and is connected to the control unit 12. To the latter there is also connected a torque rate adjusting means 16 by which a desirable value of the torque changing speed dM/dt may be set.
  • the control unit 12 comprises a programmable processor in which all necessary data for a tightening process are installed.
  • Fig 3 further shows that the power tool carries a sensing means 25 for detecting the actual torque values during operation of the tool.
  • This sensing means 25 is connected to a comparating unit 26 in which the actual sensed torque values are compared to a desired set value. As the actual sensed value reaches the preset value, a signal is delivered to the control unit 12.
  • the device shown in Fig 4 comprises a pneumatic power tool 30 supplied with pressure air via two parallel feed lines 31, 32, one of which communicating with a pressure air source via a valve 33, whereas the other communicates with a pressure accumulator 35 via a valve 36 and an adjustable restriction 37.
  • both valves 33, 36 are open permitting pressure air to flow from the pressure air source to the tool 30 as well as to the accumulator 35.
  • the valve 33 is closed while valve 36 is still open letting the pressure air stored in the accumulator 35 maintain the tool in operation for another time interval ⁇ t.
  • the emptying speed of the accumulator is determined by the setting of restriction 37, and along with a decreasing pressure in the accumulator feed line 32, the torque delivered by the tool 30 decreases.
  • the emptying speed of the accumulator 35 corresponds directly to the decreasing rate dM/dt of the delivered torque, which means that dM/dt may be altered by adjustment of restriction 37.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
  • Basic Packing Technique (AREA)
EP19900850317 1989-09-22 1990-09-24 Method and device for tightening threaded joints Expired - Lifetime EP0419436B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8903135A SE464622B (sv) 1989-09-22 1989-09-22 Metod och anordning foer styrd aatdragning av gaengade foerband
SE8903135 1989-09-22

Publications (3)

Publication Number Publication Date
EP0419436A2 EP0419436A2 (en) 1991-03-27
EP0419436A3 EP0419436A3 (en) 1991-12-04
EP0419436B1 true EP0419436B1 (en) 1994-08-24

Family

ID=20376961

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900850317 Expired - Lifetime EP0419436B1 (en) 1989-09-22 1990-09-24 Method and device for tightening threaded joints

Country Status (4)

Country Link
EP (1) EP0419436B1 (sv)
JP (1) JPH03184774A (sv)
DE (1) DE69011790T2 (sv)
SE (1) SE464622B (sv)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5130700A (en) * 1991-03-04 1992-07-14 Snap-On Tools Corporation Electronic torque wrench and overshoot compensation circuit therefor
SE506118C2 (sv) * 1993-09-02 1997-11-10 Atlas Copco Tools Ab Metod för åtdragning av gängade förband till en önskad förspänningsnivå med hjälp av en manuellt manövrerad kraftmutterdragare innefattande en nedgängningsfas och en förspänningsfas, avkänning av momentmotståndet i förbandet samt avbrytande av rotationen vid uppnådd önskad förspänningsnivå
SE535870C2 (sv) * 2011-03-18 2013-01-22 Atlas Copco Ind Tech Ab Metod för åtdragning av skruvförband med ett handhållet kraftverktyg
WO2024000557A1 (en) * 2022-07-01 2024-01-04 Apex Brands, Inc. Electronic torque wrench with torque overshoot compensation

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2200035C3 (de) * 1971-01-06 1984-09-27 Rockwell International Corp., Pittsburgh, Pa. Werkzeug zum Festziehen von Befestigungselementen, beispielsweise Schrauben
DE3210929A1 (de) * 1982-03-25 1983-10-06 Bosch Gmbh Robert Verfahren und vorrichtung zur abschaltung von schraubvorrichtungen

Also Published As

Publication number Publication date
SE8903135D0 (sv) 1989-09-22
EP0419436A2 (en) 1991-03-27
JPH03184774A (ja) 1991-08-12
DE69011790T2 (de) 1995-04-27
SE464622B (sv) 1991-05-27
EP0419436A3 (en) 1991-12-04
SE8903135L (sv) 1991-03-23
DE69011790D1 (de) 1994-09-29

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