WO2017122866A1 - Procédé de commande d'outil à entraînement électrique - Google Patents

Procédé de commande d'outil à entraînement électrique Download PDF

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Publication number
WO2017122866A1
WO2017122866A1 PCT/KR2016/002065 KR2016002065W WO2017122866A1 WO 2017122866 A1 WO2017122866 A1 WO 2017122866A1 KR 2016002065 W KR2016002065 W KR 2016002065W WO 2017122866 A1 WO2017122866 A1 WO 2017122866A1
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WO
WIPO (PCT)
Prior art keywords
torque
electric motor
nut
rate
current
Prior art date
Application number
PCT/KR2016/002065
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English (en)
Korean (ko)
Inventor
오성섭
이종진
김준영
Original Assignee
계양전기 주식회사
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
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Application filed by 계양전기 주식회사 filed Critical 계양전기 주식회사
Publication of WO2017122866A1 publication Critical patent/WO2017122866A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B23P19/04—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes for assembling or disassembling parts
    • B23P19/06—Screw or nut setting or loosening machines
    • 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
    • B25B23/147—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors

Definitions

  • the present invention relates to a control method of a power tool, and more particularly, to a control method of a power tool capable of fastening a nut in an assembling process of an automobile or the like.
  • the fastening process of the nut is as follows. First, the nut is moved toward the workpiece while rotating along the thread of the bolt by the power tool. However, if the nut meets the workpiece, that is, at the time of seating, the rotational speed of the nut is significantly reduced. The nut is then further torqued to tighten it. This is to prevent the nut from loosening in the future. That is, the fastening process is only finished by providing a predetermined target torque to the nut to finally tighten the nut.
  • the power tool has been controlled to quickly seat the nut while rotating at high speed at low torque before seating.
  • the nut is set either to 1) continuous torque without interruption in the middle, or 2) impact torque that occurs intermittently but provides an instant impact.
  • the continuous torque has a problem that a relatively large reaction force is generated compared to the impact torque.
  • impact torque has a problem that 1) can not accurately control the size of the torque compared to the continuous torque, 2) has a relatively higher energy consumption.
  • the joint characteristics of the nut required for the completion of the fastening are different due to the difference in the friction coefficient according to the fastening part.
  • the joint characteristics do not reflect, there is a problem that the tightening accuracy is lowered when the torque is provided to the nut.
  • conventional power tools do not have a method of judging their own joint characteristics, and before the fastening process, the joint characteristics of the fastening part are determined in advance, and accordingly, the fastening process is performed by switching the mode of the power tool.
  • Embodiments of the present invention have been made to solve the above problems, to provide a control method of a power tool that can identify the joint characteristics of the fastening portion, such as nuts, reflecting this to further improve the fastening accuracy. do. In addition, it aims to be able to fasten at the same time while minimizing the energy required by the power tool.
  • an electric motor is disposed, and in a control method of an electric tool for fastening a nut by controlling a current supplied thereto, at the time when the nut is seated, A first step of determining whether the rotational speed reaches a preset speed Vt; If the speed Vt is not reached, step 2-1 of stopping current supply and tightening the nut with only the rotational inertia force of the electric motor to detect a measured torque over time to calculate a first torque rate; And a third step of sequentially providing impact torque after the rotational speed of the electric motor becomes zero, and variably controlling the measured torque for each impact torque according to the first torque rate.
  • a control method Provide a control method.
  • the increase rate with respect to the maximum value of the measured torque may be controlled to match the first torque rate.
  • the impact torque may be generated by supplying a pulse current to the electric motor.
  • the magnitude of the first pulse current generated among the pulse currents can be variably controlled by reflecting the total number of occurrences of the pulse current and its duration.
  • the pulse current is a square wave current, and an increase with respect to each initial value of the square wave current may be a constant constant.
  • a fourth step of variably controlling and correcting the increase may further include.
  • step 2-2 of supplying a brake current to the electric motor to provide a continuous torque that gradually increases so that a target torque is applied to the nut.
  • step 2-2 if the instantaneous rate of change of the rotational speed of the electric motor is greater than or equal to D, the supply of the brake current is stopped and the nut is tightened only by the rotational inertia of the electric motor, thereby detecting the measured torque over time. And calculating a second torque rate to the second torque rate.
  • step 2-3 after the rotational speed of the electric motor becomes zero, the impact torque is sequentially provided, and the increase rate of the maximum value of the measured torque for each impact torque coincides with the second torque rate.
  • 2-4 may be further controlled.
  • the first torque rate is calculated by detecting the measured torque with time only by the rotational inertia force of the electric motor, which is then referred to as a reference.
  • the increase accuracy of the maximum value of the measured torque for each impact torque provided to the nut can be matched with the first torque rate to improve the tightening accuracy. At this time, if the increase rate is inconsistent with the first torque rate, it may be corrected to further improve the fastening accuracy.
  • the braking current may be supplied to the electric motor to control the target torque to be applied to the nut, thereby minimizing the tightening energy.
  • the torque providing method may be switched to the impact torque, thereby reducing the failure rate of the fastening process.
  • the second torque rate may be calculated using only the rotational inertia force of the electric motor, and the increase rate with respect to the maximum value of the measured torque for each impact torque may be controlled based on the second torque rate. As a result, the fastening accuracy can be improved.
  • the impact torque can be reached quickly to the target torque, thereby improving productivity.
  • FIG. 1 is a flow chart showing a control method of a power tool according to an embodiment of the present invention.
  • 3 is a graph showing measured torque and pulse current over time.
  • a control method of a power tool includes 1) determining a first step (s10), 2) determining a first torque rate (a), and a second-first step (s20), 3) variably controlling the power tool. 3rd step (s30), 4) 4th step (s40) of correction, 5) 2-2 steps (s25) of providing continuous torque, 6) 2-3 steps (s26) of calculating the second torque rate And 7) steps 2-4 (s27) of controlling to match the second torque rate.
  • the control method according to an embodiment may be applied to a power tool using an electric motor as a means for providing torque.
  • the power tool may further include a current controller dedicated to the control of the current to improve the fastening accuracy.
  • the power tool may further include a speed sensor for detecting the rotational speed of the electric motor, a torque sensor for detecting the measurement torque actually applied to the nut, an encoder for detecting the rotation angle of the nut after being seated.
  • the term 'seating' refers to the movement of the nut as it moves forward along the thread of the bolt, especially when the nut's rotational speed begins to decrease due to an increase in the coefficient of friction as soon as the head of the nut meets the workpiece. Say the deployment status. On the other hand, the fastening process is completed only after tightening the nut after seating.
  • the power tool sharply increases the rotational speed of the electric motor from zero for seating. That is, by supplying a low current to the electric motor in a stationary state instantaneously, the time required for seating can be shortened.
  • the operator can calculate the fastening energy required for fastening according to the type of nuts and various fastening sites.
  • the fastening energy depends on the fastening method and the path thereof, optimization of the fastening method and the like should be preceded in order to minimize the fastening energy.
  • using the rotational inertia force of the electric motor can reduce the consumption of the fastening energy by that amount. This is a method of controlling the rotational speed of the electric motor by controlling the current supplied to the electric motor.
  • the control method of the power tool according to the embodiment mainly controls the rotational speed of the electric motor. At this time, a relatively low torque is continuously applied to the nut, but the nut can be quickly seated by the high speed rotation of the electric motor.
  • This method can accurately predict the time of seating and can further shorten the time required for seating by the high-speed rotating electric motor. As a result, the productivity of the fastening process can be improved.
  • the first step of determining (s10) determines whether the rotational speed of the electric motor has reached the preset speed Vt at the time of seating.
  • the speed Vt is an optimized speed so that the target torque is finally applied to the nut while tightening the nut after seating.
  • the speed Vt may vary depending on the type of the fastening member, the characteristics of the fastening surface, the size of the target torque, and the like.
  • the rotational speed of the electric motor may reach the speed Vt at the time of seating.
  • the rotation speed does not reach the speed Vt.
  • the second step s20 is performed. This is because, if the rotational speed does not reach the speed Vt at the time of seating, the fastening method using the rotational inertia force of the electric motor cannot provide the target torque to the nut, resulting in a fastening failure.
  • step 2-1 (s20) immediately stops supplying current supplied to the electric motor to zero its rotation speed. However, the rotational speed of the electric motor becomes zero only after a certain time elapses due to the action of the rotational inertia force. At this time, the nut is further tightened only by the rotational inertia force of the electric motor.
  • joint properties are prescribed
  • the joint properties vary depending on the coefficient of friction between the fastening surface and the nut tightened in contact with it. And, such a joint characteristic can be grasped if only the rotational inertia force acts on the nut because the supply of electric current to the electric motor is cut off.
  • the joint characteristics are obtained by detecting the rotation angle d1 and the measurement torque m1 of the nut, respectively, and then the value (m1 / d1) obtained by dividing the measurement torque by the rotation angle.
  • the maximum value of the measured torque is used.
  • the joint properties remain constant until the fastening process for each fastening site is completed.
  • the tightening process after seating is a linear region.
  • the points shown in FIG. 2 lie on a straight line.
  • the actual joint properties may vary with changes in coefficient of friction and the like as the angle of rotation of the nut increases.
  • the first torque rate ⁇ may be calculated by detecting the measured torque over time through the second-first step s20. Referring to FIG. 3, the measured torque due to the rotational inertia force increases linearly. As a result, when the increase m1-ma of the measured torque with respect to the elapsed time t1-ta is calculated
  • the impact torque is sequentially provided.
  • the impact torque is a single value preset through current control
  • the measurement torque is a set of continuous values in which the impact torque applied to the nut is actually detected through the torque sensor. At this time, it is preferable to match the maximum value of the measurement torque with the impact torque.
  • the power tool variably controls the measured torque for each impact torque in accordance with the first torque rate a. That is, the first torque rate a may provide a reference to at least one or more measurement torques that are sequentially increased to apply the target torque to the nut. Preferably, the increase rate b for the maximum value of the measured torque for each impact torque is controlled to match the first torque rate a. As such, tightening the nut to reflect the joint characteristics improves the fastening accuracy.
  • the impact torque is generated by supplying an intermittent pulse current to the electric motor.
  • the power tool variably controls the magnitude of the pulse current generated first among the pulse currents by reflecting the total number of occurrences of the pulse current and its duration.
  • the joint properties can be used to calculate the residual energy required to apply the target torque to the nut. This is because, after seating, the fastening process applies linearity.
  • the remaining energy may be divided by the number of impact torques, that is, the total number of occurrences of the pulse current may be controlled within a preset range.
  • the duration of the pulse current is relatively short due to the nature of the impact torque. At this time, the duration can be constantly controlled for all pulse currents. Therefore, the magnitude of the pulse current for generating the initial impact torque can be variably controlled by reflecting the residual energy, the total number of occurrences of the pulse current, and the duration thereof.
  • the maximum value of the measured torque for the initially supplied pulse current is m 2.
  • the power tool can detect the cumulative angle d2 through the encoder.
  • the constant increases with the slope of the first torque rate.
  • d3-d2, d4-d3, etc. which are an increase in the rotation angle with respect to the nut, will also be constant.
  • the magnitude of the initially supplied pulse current can be variably controlled as described above.
  • the pulse current is preferably a square wave current. That is, a square wave current having the same initial value and final value is supplied to the electric motor. At this time, it is preferable that the increment with respect to each initial value of the adjacent square wave current is a constant constant. As a result, the increase rate b for the maximum value of the measured torque for each impact torque can be controlled to match the first torque rate a. This is because the impact torque is proportional to the amount of energy supplied, where the magnitude of energy is proportional to the magnitude of the square wave current under the condition that the duration of each square wave current is constant.
  • a fourth step of variably controlling and correcting the increase to the initial value of each square wave current may be further included. That is, when the maximum value of each detected measurement torque exceeds the predetermined impact torque according to the first torque rate, the initial value of the square wave current can be corrected.
  • the error is calculated by comparing the maximum value of the preset impact torque and the detected measured torque with each other. The result is determined by one of three things: 1) coincidence, 2) less than and 3) greater than. In the case of 2) and 3), since the impact torque by the square wave current reflecting the actual first torque rate was not applied to the nut, the magnitude of the square wave current immediately supplied is corrected by the error.
  • the correction for the error uses a proportional expression.
  • the fastening process after seating is in theory a linear region in which the friction coefficient and the like are invariant by the first torque rate.
  • the initial value of the next square wave current is 10% in the pre-calculated increment according to the first torque rate.
  • the fastening accuracy can be improved.
  • the impact torque can be reached quickly to the target torque, thereby improving productivity.
  • the power tool continuously determines whether the preset magnitude of the impact torque and the maximum value of the measured torque are coincident with each other, and corrects the deficit if it is insufficient.
  • the fastening process is completed by cutting off the supply of the square wave current through the current controller.
  • Step 2-2 is a step of supplying a brake current to the electric motor to provide a continuous torque gradually increasing so that the target torque is applied to the nut.
  • the continuous torque is generated by the rotational inertia force of the electric motor by the speed Vt, and the speed Vt gradually decreases.
  • the deceleration rate may be constant or variable.
  • the brake current is continuously supplied to the electric motor only after the seat is changed until its target torque is applied to the nut.
  • the brake current is preferably controlled so that the magnitude thereof becomes zero at the moment when the target torque is applied to the nut.
  • the speed Vt is slowly decelerated by the brake current, and becomes zero at the moment the target torque is applied to the nut.
  • the electric motor stops.
  • the tightening process is terminated normally when the maximum value of the measured torque matches the target torque.
  • control method of the power tool including the seating of the nut and the second step (s25) of applying a target torque to the nut thereafter is to control only the rotational speed of the electric motor, thereby reducing the fastening energy required for the fastening process. can do. This is a result of precisely controlling the rotational speed while using the rotational inertia force of the electric motor.
  • step 2-3 is performed. This reflects when the instantaneous rate of change of the rotational speed of the electric motor changes due to a defect in the thread of the bolt or nut.
  • D is generally a value exceeding 0, and D may be a relatively large value when the rotational speed changes rapidly.
  • the second torque rate can be calculated by detecting the measured torque with time only by the rotational inertia force.
  • the second torque rate is also a joint characteristic, which is theoretically the same as the first torque rate a.
  • the second torque rate may be slightly different from the first torque rate in consideration of the change in the friction coefficient according to the fastening degree.
  • step 2-4 s27 of sequentially providing impact torque. That is, the manner of providing torque applied to the nut is switched to the impact torque generated intermittently.
  • the fastening method for controlling the rotational speed of the electric motor cannot finally provide the target torque to the nut when the rotational speed varies from a preset value. That is, if the rotational speed of the electric motor changes rapidly, the electric motor cannot follow the preset rotational speed even if the brake current is controlled.
  • the rate of increase with respect to the maximum value of the measured torque for each impact torque is controlled to match the second torque rate.
  • the specific reason is the same as described above, and the detailed description thereof will be omitted.
  • a square wave current is used to provide an impact torque, and the control method is the same as described above.
  • the control method of the power tool according to the above embodiment can minimize the fastening energy. In addition, when the power tool is not properly controlled, the failure of the fastening process can be prevented thereby.

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

Abstract

L'invention concerne un procédé de commande d'un outil à entraînement électrique renfermant un moteur électrique et des écrous de fixation par la commande du courant apporté au moteur électrique, le procédé de commande d'outil à entraînement électrique comprenant : étape 1 pour déterminer, lors de la mise en place d'un écrou, si la vitesse de rotation du moteur électrique atteint une vitesse prédéfinie Vt ; étape 2-1 pour, si la vitesse Vt n'est pas atteinte, suspendre l'alimentation en courant, fixer l'écrou uniquement par la force d'inertie de rotation du moteur électrique et, en même temps, détecter des couples mesurés en fonction du temps, et ainsi calculer un premier rapport de couple ; et étape 3 pour, après que la vitesse de rotation du moteur électrique est devenue nulle, consécutivement fournir un couple d'impact et commander de manière variable les couples mesurés par rapport à chaque couple de choc en fonction premier rapport de couple.
PCT/KR2016/002065 2016-01-11 2016-03-02 Procédé de commande d'outil à entraînement électrique WO2017122866A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2016-0003276 2016-01-11
KR1020160003276A KR101759301B1 (ko) 2016-01-11 2016-01-11 전동 공구의 제어 방법

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WO2017122866A1 true WO2017122866A1 (fr) 2017-07-20

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4140650A1 (fr) * 2021-08-23 2023-03-01 Metabowerke GmbH Procédé permettant de faire fonctionner un tournevis pour pose à sec, programme informatique et tournevis pour pose à sec

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102291032B1 (ko) * 2019-02-21 2021-08-20 계양전기 주식회사 전동 공구 및 이의 제어 방법

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4987669A (en) * 1989-02-10 1991-01-29 Mazda Motor Corporation Method of tightening screw
US5154242A (en) * 1990-08-28 1992-10-13 Matsushita Electric Works, Ltd. Power tools with multi-stage tightening torque control
US5315501A (en) * 1992-04-03 1994-05-24 The Stanley Works Power tool compensator for torque overshoot
KR100203571B1 (ko) * 1995-07-11 1999-06-15 마츠오카 마코토 최적시간 볼트체결방법
KR20080003244A (ko) * 2006-06-30 2008-01-07 닛또 세이꼬 가부시키가이샤 나사 부품 체결기

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4987669A (en) * 1989-02-10 1991-01-29 Mazda Motor Corporation Method of tightening screw
US5154242A (en) * 1990-08-28 1992-10-13 Matsushita Electric Works, Ltd. Power tools with multi-stage tightening torque control
US5315501A (en) * 1992-04-03 1994-05-24 The Stanley Works Power tool compensator for torque overshoot
KR100203571B1 (ko) * 1995-07-11 1999-06-15 마츠오카 마코토 최적시간 볼트체결방법
KR20080003244A (ko) * 2006-06-30 2008-01-07 닛또 세이꼬 가부시키가이샤 나사 부품 체결기

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4140650A1 (fr) * 2021-08-23 2023-03-01 Metabowerke GmbH Procédé permettant de faire fonctionner un tournevis pour pose à sec, programme informatique et tournevis pour pose à sec

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