JP2011110672A - Fastening device and fastening method by rotation angle method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fastening device and a fastening method by a rotation angle method, which optimally perform fastening work by determining a snag point for every fastening work. <P>SOLUTION: This fastening device is provided with a driving part 11 for rotating and fastening a fastening part 2, a detecting part 12 for detecting torque applied to the fastening part 2 and the rotation angle of the fastening part 2, and a determining part 14 for determining the snag point from a value detected by the detecting part 12. The determining part 14 calculates a variation in the torque at every specific rotation angle of the fastening part 2, and determines as the snag point when its variation is within a range regarded constant. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tightening device for tightening parts such as screws and bolts, and a tightening method using a rotation angle method, and more specifically, a snag point (also referred to as a “seating point” in a rotation angle-torque diagram of the tightening part. )) Can be obtained for each tightening operation, and relates to a tightening method using a rotation angle method.

  In an operation process for manufacturing an assembly product such as an automobile, an assembly operation or an assembly operation that is fastened with bolts or nuts is performed. When loosening occurs in a fastener such as a bolt or a net, the fastening function itself is lost. The main cause of loosening is insufficient tightening. In order to prevent loosening, the loosening is prevented by improving the tightening accuracy.

  Patent Document 1 discloses a method for obtaining an optimum condition of bolt and nut rotation angle method tightening for obtaining a target axial force with minimum variation in axial force when managing the axial force of a bolt.

  It is said that there is a certain relationship between the rotation angle of the bolt and the axial force that changes accordingly, and when the bolt is rotated, the axial force increases slowly and then between the rotation angle and the axial force. After that, the bolt material reaches the yield point and the axial force does not increase according to the rotation angle. Since this rotation angle-axial force diagram varies depending on the manufacturing variation of the tightened product, there is a method of managing the tightening angle to obtain the target tightening axial force as a method of managing the axial force of the bolt. This method starts from a certain reference value and rotates it by an angle determined by a bolt to obtain a target tightening axial force. This reference value is the starting point of the tightening angle, and the torque at this time is called the snag torque.

  Conventionally, a large number of bolts are prepared, data on the combination of appropriate snag torque and rotation angle is measured, and the optimum set of snag torque and rotation angle is set to obtain the desired tightening axial force. I was managing. In Patent Document 1, a plurality of bolts are tightened by an assumed snag torque and an angle, respectively, a variation in axial force with respect to each assumed snag torque tightening angle is obtained, and a torque value when the variation in axial force is minimized is defined as a snag torque. I have decided. Thereby, the combination of the snag torque and the rotation angle is made appropriate, and the variation in the axial force can be minimized when the bolt tightening is performed by the combination of the snag torque and the rotation angle.

JP 2000-158355 A

  However, in the method disclosed in Patent Document 1, that is, the method for obtaining the optimum conditions for bolt and nut rotation angle method tightening, it is necessary to prepare a plurality of bolts in advance and perform an experiment and obtain the snag torque from the results. There is.

  Also, if the friction coefficient differs between the experiment and the actual fastening, an appropriate snag torque is not required, and the result is that tightening work such as bolts and nuts is not performed. I will.

  Therefore, an object of the present invention is to provide a tightening device and a tightening method based on a rotation angle method that can optimally perform a tightening operation by obtaining a snag point for each tightening operation.

  In order to achieve the above object, a tightening device according to the present invention includes a drive unit that rotates and tightens a tightening component, a detection unit that detects torque applied to the tightening component and a rotation angle of the tightening component, and A determination unit that determines a snag point from a value detected by the detection unit, the determination unit calculates a torque change amount at each fixed rotation angle of the tightening part, and a range in which the change amount is considered constant It is characterized by determining when it becomes a snag point.

  The tightening method according to the rotation angle method of the present invention is characterized in that a change in torque value with respect to a minute rotation angle of a tightening part is obtained, and a snag point is determined when the amount of change is within a range that is considered constant. And

  According to the present invention, it is not necessary to perform a number of experiments for obtaining the snag point in advance, and furthermore, the tightening operation can be reliably performed by eliminating the influence that the friction coefficient differs for each tightening.

It is a functional block diagram of the clamping device concerning an embodiment of the present invention. It is a figure for demonstrating the fastening method by the rotation angle method which concerns on embodiment of this invention. It is a flowchart in the fastening method by the rotation angle method which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and extends to the scope described in the claims and the equivalent scope thereof. Needless to explain.

  FIG. 1 is a configuration diagram of a tightening device according to an embodiment of the present invention. A tightening device 1 according to an embodiment of the present invention includes a drive unit 11 that performs tightening by applying a rotational force to a tightening component 2 such as a screw or a nut, and a detection that measures a rotation angle and torque of the tightening component 2. Unit 12, a collection unit 13 that captures data from detection unit 12, and a determination unit 14 that determines a snag point from the data captured by collection unit 13.

  The drive unit 11 abuts on or is attached to the tightening component 2 and applies a rotational force to the tightening component 2. When the fastening component 2 is a bolt having a head portion 2a and a screw main body portion 2b, the drive unit 11 grips the head portion 2a of the bolt 2 and rotates the head portion 2a. A switch or the like (not shown) is attached to the drive unit 11. When the switch is turned on, the drive unit 11 rotates the fastening component 2, and when the stop signal is input from the determination unit 14, the rotation is stopped. Instead of the switch, the rotation may be started when the drive unit 11 receives a signal for starting the rotation.

  The detection unit 12 includes a torque sensor and a rotation sensor, and measures the torque applied to the tightening component 2 and the rotation angle of the tightening component 2. The measurement by the sensor is performed in units of time, for example.

  The collection unit 13 samples the torque and rotation angle data measured by the detection unit 12 at arbitrary intervals and outputs the sampled data to the determination unit 14.

  The determination unit 14 determines a snag point from the torque and rotation angle sampling data output from the collection unit 13. The determination unit 14 sequentially obtains the torque T with respect to a certain rotation angle Δθ from the sampled torque T and rotation angle θ data. That is, a change in the value of the torque T with respect to a constant rotation angle Δθ is obtained while observing the change in the input rotation angle θ. When the change in the value of the torque T becomes constant, the snag point is determined. Details will be described later. The determination unit 14 may be realized by a logic circuit or may be realized by executing a determination program by a computer.

  Next, a tightening method based on the rotation angle method according to the embodiment of the present invention will be described. FIG. 2 is a view for explaining a tightening method by a rotation angle method according to the embodiment of the present invention. In FIG. 2, the horizontal axis represents the rotation angle and the vertical axis represents the torque. The graph shown in FIG. 2 is also obtained by plotting the rotation angle and torque values measured by the detection unit 12. Each value of the rotation angle and torque is sampled by the detection unit 12 and the collection unit 13, and the determination unit 14 obtains the amount of change in the torque value change ΔT with respect to a certain minute angle Δθ. As the snag point is approached, the increase amount of the minute torque amount ΔT becomes a constant value. Therefore, in the tightening method based on the rotation angle method according to the present invention, when the minute torque amount ΔT, that is, the torque change amount ΔT becomes constant, the snag point is set, and the value of the torque T at that time is the snag torque.

  Hereinafter, the tightening method by the tightening apparatus 1 shown in FIG. 1 will be described in detail. FIG. 3 is a diagram showing a flow in the determination unit 14 in particular in the tightening method by the rotation angle method according to the embodiment of the present invention.

  Specifically, assuming that the members 5a and 5b are fastened with the fastening parts 2 as illustrated in FIG. 1, the fastening parts 2 are inserted with the members 5a and 5b overlapped. In this figure, the nut 5c is fixed to the lower side of the member 5b, and is tightened by the tightening component 2 being screwed together. When the switch of the drive unit 11 is turned on, the drive unit 11 receives a drive start signal and a determination start signal is input to the determination unit 14 (STEP 1). Then, the drive part 11 begins to rotate the fastening component 2.

The detection unit 12 measures the rotation angle θ of the tightening component 2 and the torque T applied from the drive unit 11 to the tightening component 2 at predetermined time intervals. The collection unit 13 receives the measurement data input. When the detection unit 12 has first input of the rotation angle theta (Yes in STEP2), collecting unit 13 outputs the determination unit 14 calculates the torque _{T i} for small constant angle per (STEP3). That is, the collecting unit 13 has inputs of torque values T ₁ , T ₂ ,... For each rotation angle θ ₁ , θ ₂ (= θ ₁ + Δθ),. Change amounts ΔT ₁ (= T ₂ −T ₁ ), ΔT ₂ (= T ₃ −T ₂ ),... Are obtained.

When the amount of change in the torque value becomes constant (YES in STEP 5), it is determined that the snag point has been passed (STEP 6), and the torque value T at that time is determined. Let _i be the snag torque. When the determination unit 14 determines that the snag point has been passed, the determination unit 14 determines whether or not the tightening component 2 further rotates by a predetermined angle from that time, and determines that the tightening component 2 has further rotated by the predetermined angle. 2 outputs a stop signal. Each time the torque value T _i is input, STEP 4 and STEP 5 are performed. If STEP 5 is No, _i is incremented by 1 in STEP 6.

  As described above, according to the embodiment of the present invention, since the snag point is determined for each tightening, a preliminary experiment becomes unnecessary. Since the snag point is obtained for each tightening operation with the actual tightening component 2, it contributes to maintaining the quality of whether the tightening operation has been performed reliably. Even if there is a difference in the coefficient of friction of the tightening component 2 for each tightening operation, the snag point can be obtained in consideration of the difference.

In the above description, when the torque change amount ΔT _i for each small constant rotation angle Δθ is constant, that is, the i-th when ΔT _i and ΔT _{i + 1} are the same, the snag point is used. In consideration of measurement errors and the like, if the amount of change in the torque value for each minute constant rotation angle Δθ is within a predetermined range (when ε in STEP 5 in FIG. 3 is not zero), the amount of increase in the torque value is constant. In view of this, a snag point may be set when it falls within a predetermined range.

1: Tightening device 2: Tightening parts (bolts)
2a: head 2b: screw body 5a, 5b: member 5c: nut 11: drive unit 12: measuring unit 13: collecting unit 14: determining unit

Claims (3)

A drive unit that rotates and tightens a tightening component, a detection unit that detects a torque applied to the tightening component and a rotation angle of the tightening component, and a determination that determines a snag point from a value detected by the detection unit With
The tightening device, wherein the determination unit calculates a torque change amount for each fixed rotation angle of the tightening component and determines a snag point when the change amount is within a range that is considered constant.   The said determination part outputs the signal which stops rotation of the said fastening component with respect to the said drive part, if it determines with the fastening part having rotated only the predetermined angle from the rotation angle in a snag point. Tightening device.   A tightening method based on a rotation angle method in which a change in torque value with respect to a minute rotation angle of a tightening part is obtained, and a snag point is determined when the amount of change is within a constant range.

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