JP5293372B2 - Method for measuring the tightening angle of impact tightening tools - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance accuracy of measurement of a fastening angle in an impact fastening tool using fastening torque generated in a pulse-like form. <P>SOLUTION: A snug torque value T<SB>s</SB>and a cut torque value T<SB>c</SB>are previously set. A detection value of a torque sensor regarding initial fastening torque firstly becoming a torque value Ts or more after beginning of fastening is made to T<SB>s1</SB>, and an integration value of a detection value of an angle sensor after beginning of fastening until the first fastening torque is made to &theta;<SB>s1</SB>. The detection value of the torque sensor regarding the fastening torque immediately before the first fastening torque is made to T<SB>b</SB>, and an integration value of the detection value of the angle sensor after beginning of fastening until the fastening torque immediately before it is made to &theta;<SB>b</SB>. An integration value of the detection value of the angle sensor from after beginning of fastening to the completion fastening torque, i.e., the pulse-like fastening torque becoming the torque value T<SB>c</SB>or more is made to &theta;<SB>c1</SB>. In this case, the fastening angle &theta;<SB>a</SB>is calculated by the following equation (1) &theta;<SB>a</SB>=&theta;<SB>c1</SB>-[&theta;<SB>b</SB>+ä(&theta;<SB>s1</SB>-&theta;<SB>b</SB>)&times;(T<SB>s</SB>-T<SB>b</SB>)/(T<SB>s1</SB>-T<SB>b</SB>)}]. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for measuring a tightening angle of an impact tightening tool.

The impact tightening tool converts rotational energy of a motor or the like into a pulsed tightening torque and rotates the rotating shaft. By tightening the tip of the rotary shaft of the impact tightening tool and the head of the screw and driving the motor, the screw can be tightened. When tightening screws such as bolts and nuts using impact tightening tools, quality control is performed for tightening screws by detecting the tightening torque and tightening angle. For example, Patent Document 1 discloses a method of measuring a tightening angle in an impact tightening tool including a torque sensor that detects a tightening torque of screws and an angle sensor that detects a rotation angle of a rotating shaft. Yes. In Patent Document 1, a snag torque T _s is arbitrarily set in advance, and the detected values of the angle sensor are integrated from the time when the snag torque reaches T _s to the end of tightening of the screws. The integrated value of the detected angle values is used as the screw tightening angle. This eliminates the effects of noise such as camera shake and rebound, and enables accurate tightening angle measurement.

Japanese Patent Laid-Open No. 2007-30056

However, the pulsating tightening torque changes rapidly with time, and the angle of the rotating shaft also changes stepwise. For this reason, it is very difficult to accurately detect the rotation angle of the rotating shaft when the tightening torque becomes T _s . As a result, when a pulsed torque exceeding T _s is applied, the rotation angle η _sx of the rotating shaft at the time T _sx (T _sx > T _s ) which is the peak value of the pulse is detected. Since T _sx > T _s , the angle η _sx is larger than η _s which is the rotation angle of the rotating shaft when the torque is T _s . Furthermore, the difference between η _sx and η _s increases as the difference between T _sx and T _s increases.

In Patent Document 1, when tightening is performed with a torque T _s1 (T _s1 > T _s ) having a peak value exceeding T _s for the first time after starting the tightening operation, the peak value T _s1 is reached. The rotation angle η _s1 is detected, and η _s1 is set to the zero point. Using η _s1 as a zero point, the integrated value of the angle sensor until the end of tightening is calculated. The values of T _s1 and η _s1 vary depending on each tightening operation, and the zero point η _s1 does not necessarily coincide with η _s . For this reason, the integrated value of the detection values of the angle sensor varies, and the measurement accuracy of the tightening angle cannot be ensured.

The present invention includes a torque sensor that detects the tightening torque of screws and an angle sensor that detects the rotation angle of the screws, and performs tightening work by applying a pulse-like tightening torque to the screws. The present invention relates to a method for measuring a fastening angle of an impact fastening tool to be performed. In the measurement method of the present invention, the snug torque value T _s, it sets the cut-torque value T _c in advance. The detected value of the torque sensor for the initial tightening torque, which is the first pulse tightening torque that has exceeded the torque value T _s for the first time after the start of screw tightening, is T _s1, and the initial tightening is performed after the start of screw tightening. The integrated value of the detected values of the angle sensor up to the attached torque is θ _s1 . The detection value of the torque sensor for the previous tightening torque the pulse-like tightening torque immediately before the torque for initial tightening and T _b, the detection value of the angle sensor after the start tightening screws until the torque with just before tightening the integrated value and θ _b. The integrated value of the detected value of the angle sensor from the start of screw tightening to the end tightening torque, which is the pulsed tightening torque that is equal to or greater than the torque value _Tc , is defined as θ _c1 . In this case, to calculate the tightening angle theta _a at the end tightening screws by equation (1) below.
θ _a = θ _c1 − [θ _b + {(θ _s1 −θ _b ) × (T _s −T _b ) / (T _s1 −T _b )}] (1)

In the present invention, focusing on the fact that the torque value and the angle value are in a substantially proportional relationship in the initial stage of the tightening operation, the proportionality is determined based on the actually measured torque detection values T _s1 and T _b and the angle detection values θ _s1 and θ _b. using a constant _{K = (θ s1 -θ b)} / (T s1 -T b), calcd theta _s (calculated) of the corresponding theta _s to the snug torque value Ts set = θ _b + {( θ _s1 −θ _b ) × (T _s −T _b ) / (T _s1 −T _b )} is calculated. The tightening angle θ _a = θ _c1 −θ _s is calculated as θ _s = θ _s (calculated value). Compared to the conventional case where θ _s = θ _s1 , the value used as θ _s , which is the zero point of the integrated angle value, is less likely to vary. Even if θ _s1 and θ _b vary for each tightening operation, the value used as θ _s is less likely to vary. Since the variation in the value used as θ _s , which is the zero point of the integrated angle value, is small, the accuracy of angle detection can be improved.

  According to the present invention, it is possible to improve the accuracy of tightening angle measurement in an impact tightening tool using a tightening torque generated in a pulse shape.

1 is a schematic diagram of an impact tightening tool according to Embodiment 1. FIG. 2 is a flowchart of a control method according to the first embodiment. The figure which shows the time-dependent change of the detected value of the torque sensor which concerns on Example 1, and the integrated value of the detected value of an angle sensor.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view showing the structure of an impact tightening tool 1 according to this embodiment. The impact tightening tool 1 detects the torque of the main body 10, the grip 11, the operation switch 12, the motor 13 built in the main body, the hydraulic torque generator 14, the rotating shaft 15, and the rotating shaft 15. And an angle sensor 3 that detects the rotation angle of the rotary shaft 15. The torque sensor 2, the angle sensor 3, and the motor 13 are connected to a control device 40 installed outside the impact tightening tool 1.

  When the operation switch 12 is pressed, the motor 13 is driven, whereby the torque generator 14 is driven. The torque generator 14 is filled with oil, and the rotational energy of the motor 13 is converted to the oil pressure of the oil, increasing the oil pressure. As a result, a pulsed tightening torque for rotating the rotating shaft 15 can be obtained intermittently.

  For example, when performing a bolt tightening operation, a socket having a recess that fits into the head of the bolt to be tightened is attached to the tip of the rotating shaft 15. When the grip 11 is gripped, the socket is fitted to the head of the bolt, and the operation switch 12 is pressed, a pulsed tightening torque can be applied to the bolt.

  FIG. 2 is a diagram illustrating a flowchart of the control performed by the control device 40 during the tightening operation according to the present embodiment. When the tightening operation is started, as shown in step S11, the torque detection value T output from the torque sensor 2 and the integrated value θ obtained by integrating the angle detection value output from the angle sensor 3 are stored in the control device 40. Stored in the department.

The storage unit of the control device 40 stores a preset snag torque value Ts and a cut torque value _Tc . In the next step S13, it is determined whether or not the torque detection value T is equal to or greater than the cut torque value _Tc . If T < _Tc , the process returns to step S11. If T ≧ _Tc , the process proceeds to step S15. That is, the control device 40 repeatedly executes step S11 until the detected torque value output from the torque sensor 2 exceeds the cut torque value _Tc .

  In step S15, the control device 40 performs tightening end control. Specifically, a stop signal is output to the motor 13 to stop the tightening operation. Note that the fastening operation may not be stopped under the control of the control device 40. For example, a mechanical torque generator may be used as the torque generator 14, and the torque generation may be automatically stopped when the torque value exceeds a threshold value.

In step S17~ step S23, the control unit 40 calculates the tightening angle theta _a of screws from the integrated value theta of the torque detection value T and angle detection value stored in the storage unit, and outputs to the display unit or the like. Hereinafter, this will be specifically described with reference to FIG.

  FIG. 3 is a diagram illustrating an example of a tightening operation performed using the impact tightening tool 1 of the present embodiment. The first axis of the vertical axis represents the detection value T of the torque sensor 2, and the second axis of the vertical axis represents the integrated value θ of the detection value of the angle sensor 3. The horizontal axis indicates the time of the tightening operation, and the time has elapsed from the first axis side to the second axis side on the vertical axis. As shown in FIG. 3, the torque detection value T has a pulse shape, and its peak value increases with time. The integrated value θ of the detected angle value increases substantially in a step shape when a pulsed tightening torque is generated.

In step S17, the control device 40 sets the detected value of the torque sensor to T _s1 for the initial tightening torque, which is the pulse-shaped tightening torque that becomes equal to or greater than the torque value T _s for the first time after the start of tightening. As shown in FIG. 3, the detected torque value T _s1 indicates the maximum value of the initial tightening torque. Further, the integrated value of the detected values of the angle sensor from the start of tightening to the time when the detected torque value becomes T _s1 is defined as θ _s1 . The storage unit of the control device 40 stores a torque detection value T _c1 at the end of tightening and an integrated value θ _c1 of the detection value of the angle sensor.

Further, the control unit 40, the pulse-like torque with just before tightening a tightening torque immediately before the torque for initial tightening, the detection value of the torque sensor and T _b. As shown in FIG. 3, the torque detection value T _b is the maximum value of w immediately before tightening torque. Further, an integrated value of the detected value of the angle sensor after the start tightening to the point where the torque detection value becomes T _b and theta _b.

In step S19, θ _s (calculated value) is calculated by the following equation (2) using T _s1 , θ _s1 , T _b , θ _b , and θ _c1 read in step S17.
θ _s (calculated value) = θ _b + {(θ _s1 −θ _b ) × (T _s −T _b ) / (T _s1 −T _b )} (2)

In step S21, the following equation (3), the angle theta _a is calculated tightening. Angle theta _a fastening corresponds to the angle theta _a shown in FIG.
θ _a = θ _c1 −θ _s (calculated value) (3)

In subsequent step S23, the tightening angle theta _a is output to the display device or the like, the control is ended.

As shown in FIG. 3, the torque T _s1 indicates the maximum value of the pulsed tightening torque that becomes the snag torque T _s or more for the first time after the tightening operation is started. From FIG. 3, it is clear that T _s1 > T _s . As the difference between T _s1 and T _s increases, the difference between θ _s1 and θ _s also increases. Further, the torque T _s1 varies depending on the tightening operation every time.

When this θ _s1 is used as the zero point θ _s , the tightening angle becomes the size indicated by φ _a in FIG. As shown in FIG. 3, clearly phi _a becomes smaller than theta _a. In addition, θ _s1 is shifted every time and does not always coincide with θ _s . Since θ _s1 used as the zero point varies, the accuracy of tightening angle measurement varies.

On the other hand, in the measurement method according to the present embodiment, paying attention to the fact that the torque value and the angle value are in a substantially proportional relationship in the initial stage of the tightening operation, the measured torque detection values T _s1 and T _b , Θ _s is calculated using the detected angle values θ _s1 and θ _b . For this reason, the value used as θ _s , which is the zero point of the integrated angle value, is less likely to vary. Even if θ _s1 and θ _b vary for each tightening operation, the value used as θ _s is less likely to vary. Since the variation in the value used as θ _s , which is the zero point of the integrated angle value, is small, the accuracy of angle detection can be improved.

In the present embodiment, during the tightening operation, the control device only stores the detected value T of the torque sensor and the integrated value θ of the detected value of the angle sensor. While performing the calculation or the like of the theta _a, not limited thereto, theta _a calculated substantially by the formula (1) is only to be determined as a fastening angle. For example, θs (calculated value) may be calculated using Equation (2) during the tightening operation. Alternatively, θ _a may be calculated by setting θ _s (calculated value) calculated during the tightening operation as a zero point and integrating the detected values of the angle sensor.

  In the above embodiment, the hydraulic torque generator is used. However, the present invention is not limited to this, and any device can be used as long as a pulsed tightening torque can be obtained. For example, a pulsed torque may be obtained by engaging / disengaging the clutch. Moreover, although the control apparatus was installed outside the impact fastening tool, it may be incorporated in the impact fastening tool.

  As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

DESCRIPTION OF SYMBOLS 1 Impact fastening tool 2 Torque sensor 3 Angle sensor 10 Main body 11 Grip 12 Operation switch 13 Motor 14 Torque generator 15 Rotating shaft 40 Control device

Claims (1)

Impact tightening that includes a torque sensor that detects the tightening torque of the screws and an angle sensor that detects the rotation angle of the screws, and performs a tightening operation by applying a pulsed tightening torque to the screws. A method for measuring the tightening angle of a tool,
Snag torque value T _s and cut torque value T _c are set in advance,
The detected value of the torque sensor for the initial tightening torque, which is a pulse-shaped tightening torque that becomes equal to or greater than the torque value T _s for the first time after starting the tightening of screws, is T _s1 ,
The integrated value of the detected values of the angle sensor from the start of screw tightening to the initial tightening torque is θ _s1 ,
The detection value of the torque sensor of the pulse-like torque with just before tightening a tightening torque immediately before the first tightening torque and T _b,
The integrated value of the detected value of the angle sensor from the start of screw tightening to the immediately preceding tightening torque is θ _b ,
When the integrated value of the detected value of the angle sensor from the start of screw tightening to the end tightening torque, which is the pulsed tightening torque when the torque value becomes equal to or greater than _Tc , is θ _c1 ,
The tightening angle θ _a at the end of screw tightening is expressed by the following formula:
θ _a = θ _c1 − [θ _b + {(θ _s1 −θ _b ) × (T _s −T _b ) / (T _s1 −T _b )}]
Method of measuring the tightening angle calculated by

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