EP3419789A1 - Outil électrique - Google Patents

Outil électrique

Info

Publication number
EP3419789A1
EP3419789A1 EP17704723.0A EP17704723A EP3419789A1 EP 3419789 A1 EP3419789 A1 EP 3419789A1 EP 17704723 A EP17704723 A EP 17704723A EP 3419789 A1 EP3419789 A1 EP 3419789A1
Authority
EP
European Patent Office
Prior art keywords
output shaft
angle
torque
monitoring
surrounding area
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.)
Withdrawn
Application number
EP17704723.0A
Other languages
German (de)
English (en)
Inventor
Erik Vilhelm Persson
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 Industrial Technique 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 Industrial Technique AB filed Critical Atlas Copco Industrial Technique AB
Publication of EP3419789A1 publication Critical patent/EP3419789A1/fr
Withdrawn legal-status Critical Current

Links

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
    • B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
    • 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
    • B25B23/142—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for hand operated wrenches or screwdrivers
    • B25B23/1422—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for hand operated wrenches or screwdrivers torque indicators or adjustable torque limiters
    • B25B23/1425—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for hand operated wrenches or screwdrivers torque indicators or adjustable torque limiters by electrical means
    • 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

  • the invention relates to a method of performing a tightening operation by means of a handheld power wrench with a first and a second angular measuring device.
  • the invention also relates to a power tool adapted to perform said method.
  • Modern professional power wrenches are provided with a number of sensors and means for detecting and reporting parameters of on-going and performed tightening operations .
  • Parameters that may be detected and reported include the applied torque, the installed angular increment of a bolt, screw or nut of a joint and in some instances the clamp force installed into the joint.
  • WO 2015/139952 Al discloses a method of obtaining a high clamp force accuracy in a threaded joint mounting process.
  • a gyro or the like is used to monitor the clamp force installed into a joint.
  • the gyro is used to monitor the angle of the tool, which is recalculated to a clamp force.
  • the clamp force is a parameter that is relevant in many tightening operations, but in some operations other parameters may however be more interesting and more easily monitored.
  • a method that provides an improved accuracy for tightening operations, but which offers an alternative to a method in which the operation is governed based on the clamp force installed into a joint.
  • An object of the invention is to provide a method of performing an operation of tightening a joint with an increased accuracy.
  • an object of the invention is to provide an accurate monitoring of the installed angle of a handheld torque delivering power tool without the use of torque arms or other means for
  • this object is achieved by means of a method of tightening a joint by means of a handheld torque delivering power tool, the power tool comprising:
  • a first angular measuring device for monitoring the angle of rotation of the output shaft about the axis of the output shaft with respect to the housing
  • a second angular measuring device arranged to monitor angle of rotation of the housing around the axis of the output shaft relative to the surrounding area
  • the invention relates to a handheld torque delivering power tool comprising:
  • a first angular measuring device for monitoring the angle of rotation of the output shaft about the axis of the output shaft with respect to the housing
  • a second angular measuring device arranged to monitor angle of rotation of the housing around the axis of the output shaft relative to the surrounding area
  • control unit wherein the control unit is arranged to perform the following steps:
  • a yield tightening is performed, which indicates that a plastic deformation of the fastener in the joint is achieved.
  • the step of interrupting the tightening operation is preceded by a step of identifying the appearance of a substantially linear torque per angle coefficient and registering a linear gradient that corresponds to the substantially linear torque per angle of rotation, wherein the predetermined stop gradient is set in relation to said linear gradient.
  • This step is in the power tool achieved by the control unit.
  • the tightening operation is interrupted at a point where the instantaneous differential coefficient of the monitored torque per monitored angle of the output shaft relative to the surrounding area has reached below 90% of the linear gradient, or 75% of the linear gradient. This step may also be achieved by the control unit.
  • Fig. 1 is a diagram of the dependency of the torque T with respect to an angle a of an output shaft during a tightening operation
  • Fig. 2 shows a power tool in an initial position
  • Fig. 3 shows a power tool in an position where both the tool housing and output shaft have rotated with respect to the axis of the output shaft
  • Fig. 4 shows the steps of the inventive method. Detailed description of the shown embodiment of the invention
  • Fig. 1 shows a diagram of the dependency of the torque T that is installed into a joint with respect to an angle a by which a fastener of the joint is rotated.
  • the curve represents a typical curve of a tightening operation in which the joint is tightened into the yield area, i.e. such that a plastic deformation of the fastener is achieved.
  • the torque is constant during a first period in which the fastener is rotated towards the joint, i.e.
  • the tightening operation may be set to be interrupted when the differential coefficient reaches a predetermined stop
  • the predetermined stop gradient k st o P at which the tightening should be interrupted may be set in relation to a specific fraction of the linear gradient ki in the linear portion, i.e.
  • the gradient must however be a compromise between the need to interrupt the tightening before the fastener risks to rupture and the need to be sure that the plastic deformation has actually started .
  • the predetermined stop gradient k s to P at which the tightening should be interrupted differs too little from the linear gradient ki of the linear portion the tightening operation may be interrupted prematurely due to a natural variation or a tolerance fault. If, on the other hand, the predetermined stop gradient k s to P is set too high the risk of rupture of the fastener will increase.
  • the predetermined stop gradient k stop may be tested by a skilled person, and may
  • the tightening operation may e.g. be set to be interrupted when the instantaneous differential coefficient dT/da has reached below 75% or 90% of the linear gradient ki .
  • the angle at which the tightening operation is interrupted may be defined as a s to P and the corresponding torque at which the tightening operation is interrupted may be defined as T s to P , even though the operation is not controlled towards a specific angle nor a specific torque but to the
  • Another feature concerned with a yield tightening is to prepare for the interruption in advance such that the targeted the predetermined stop gradient k st o P is met.
  • special care has to be taken to the movement of the tool .
  • Figures 2 and 3 show a power tool in two different positions.
  • the power tool is illustrated in an initial position and in figure 3 the power tool is shown in an off-set position in which the output shaft has rotated about the axis of the output shaft with respect to the housing with an angle a , and in which the housing has rotated around the axis of the output shaft relative to the
  • the combined angle a is hence the sum of a and (3 ⁇ 4 and corresponds to the rotation of a fastener with respect to a joint, the joint being fixed with respect to the surrounding area.
  • 105 Calculating a differential coefficient of the monitored torque per monitored angle; 106 -Identifying an installed clamp force, e.g. by identifying the appearance of a substantially linear torque per angle coefficient;
  • Step 106 may be omitted and in such a case step 107 will be defined in an absolute number, i.e. as a specific predetermined decrease of the torque per angle coefficient and not in relation to the substantially linear torque per angle coefficient.
  • the power tool 10 is provided with an output shaft 11, which is to be connected to and drive the rotation of a fastener, and a handle 12 at which the power tool is to be held by an operator.
  • the power tool may also be provided with a second handle for positioning of the operator's other hand.
  • a motor 13 and preferably a gear (not shown) is arranged to drive the output shaft .
  • a housing 14 is arranged to house the motor 13, gears and other features, such as a first angular measuring device 15, a second angular measuring 16 device torque monitoring device 17 and a control unit 18.
  • the first angular measuring device 15 is arranged to monitor the angle of rotation a of the output shaft 11 about the axis of the output shaft with respect to the housing 14.
  • the second angular measuring device 16 is arranged to monitor the angle of rotation (3 ⁇ 4 of the housing 14 around the axis of the output shaft 11 relative to the surrounding area.
  • the torque monitoring device 17 is arranged to monitor the torque T during a tightening operation .
  • a control unit 18 is arranged in the power tool to control the operation of the tool based on the monitored torque T and angles of rotation a and
  • control unit 18 an instantaneous differential coefficient dT/da of the monitored torque T per monitored angle a of the output shaft 11 relative to the surrounding area is calculated.
  • the control unit 18 is arranged to instruct the motor 13 to interrupt the tightening
  • the decrease may be defined in absolute numbers or as fraction of the differential coefficient ki in the linear portion of the curve shown in figure 1.
  • angles a n defined in the diagram are all the sum of the angles a a and ab provided by the first and second angular measuring device 15 and 16, respectively.
  • ai corresponds to the sum of the individually monitored angles a a -i and oib-i ⁇
  • a 2 a a -2 + a b -2
  • a s to P a a - s to P + a b -sto P .

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)

Abstract

La présente invention concerne un procédé de serrage d'un joint au moyen d'un outil électrique portatif, le procédé comprenant les étapes suivantes : • surveillance du couple (T) pendant une opération de serrage ; • surveillance d'un angle (α) de l'arbre de sortie (11) par rapport à la zone environnante au moyen d'une surveillance combinée d'un angle de rotation (αa) de l'arbre de sortie (11) autour de l'axe de l'arbre de sortie par rapport au boîtier (14), et un angle de rotation (αb) du boîtier (14) autour de l'axe de l'arbre de sortie par rapport à la zone environnante ; • calcul d'un coefficient différentiel instantané (dT/dα) du couple surveillé (T) en fonction de l'angle surveillé (a) de l'arbre de sortie par rapport à la zone environnante, et • interruption de l'opération de serrage en réponse à une diminution prédéterminée du coefficient différentiel instantané (dT/dα) du couple surveillé en fonction de l'angle surveillé de l'arbre de sortie par rapport à la zone environnante.
EP17704723.0A 2016-02-26 2017-02-09 Outil électrique Withdrawn EP3419789A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE1650255 2016-02-26
PCT/EP2017/052849 WO2017144281A1 (fr) 2016-02-26 2017-02-09 Outil électrique

Publications (1)

Publication Number Publication Date
EP3419789A1 true EP3419789A1 (fr) 2019-01-02

Family

ID=58018089

Family Applications (1)

Application Number Title Priority Date Filing Date
EP17704723.0A Withdrawn EP3419789A1 (fr) 2016-02-26 2017-02-09 Outil électrique

Country Status (2)

Country Link
EP (1) EP3419789A1 (fr)
WO (1) WO2017144281A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4008772A (en) * 1975-05-19 1977-02-22 Standard Pressed Steel Co. Tightening system
US4211120A (en) * 1978-08-08 1980-07-08 Sps Technologies, Inc. Tightening apparatus
DE3247618A1 (de) * 1982-12-23 1984-07-05 Deutsche Gardner-Denver Gmbh, 7081 Westhausen Verfahren zum anziehen von schraubverbindungen
DE3634895A1 (de) * 1986-10-14 1988-04-21 Egm Entwicklung Montage Verfahren und vorrichtung zum anziehen einer schraubverbindung
GB2273574B (en) * 1992-12-21 1995-11-29 Daimler Benz Ag Process and a device for the rotation-angle-monitored tightening or loosening of screw connections

Also Published As

Publication number Publication date
WO2017144281A1 (fr) 2017-08-31

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