JP2009083002A - Impact rotary tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop an appropriate tightening torque even when impact torque deteriorates with age caused by continuous use of the tool, in an impact rotary tool. <P>SOLUTION: This impact rotary tool rotatively drives a hammer 4 by a motor 2, and tightens a tightening object by applying the impact torque of the hammer 4. A control means 7 calculates the number of strokes required according to a predetermined tightening torque set value and calculates a change in the magnitude of the impact torque with time, thereby correcting the number of strokes required, and stopping the motor 2 when the number of strokes reaches the corrected number of strokes required. Thereby, even when the impact torque is reduced due to deterioration with age, the number of strokes is corrected, and the tightening object is tightened with the tightening torque set value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an impact rotary tool such as an impact wrench or an impact driver used for tightening and loosening bolts and nuts.

  The impact rotary tool is a tool that converts the rotation of the motor into hammer hitting and outputs a strong impact force when the hammer hits the anvil from the output shaft to perform tightening and relaxation work, using only a reduction gear Compared to conventional rotary tools, it can output higher torque and improves workability, so it is widely used in construction sites and assembly plants. However, the impact rotary tool may be overtightened due to the high torque characteristics, and may damage the tightening object such as a bolt. In this case, the tightening torque may be insufficient and the object to be tightened may not be fixed as desired.

  For this reason, in order to perform appropriate tightening, an impact rotary tool that estimates a tightening torque and stops the motor when the estimated tightening torque reaches a predetermined torque value has been proposed (for example, see Patent Document 1). ). The torque estimation method for an impact rotary tool disclosed in Patent Document 1 is such that when a tightening object is tightened, the friction between the tightening object and the tightening counterpart member when the tightening object advances by an angle θ at torque T. For example, the energy consumed by the hammer is almost equal to the energy given to the anvil from the hammer. Specifically, assuming that the hammer angular velocity at the time of impact is ω and the moment of inertia of the hammer is Ja, the hammer's kinetic energy Ei at the time of impact is expressed by the following Equation 1.

  When the anvil advances by the rotation angle θ due to this impact, assuming that the average torque for tightening is T, the energy Eo consumed by the tightening is expressed by the following Equation 2.

  Since the energy for rotating the anvil is given by the hammer, the torque T is calculated by the following equation 3 assuming that the energies Ei and Eo in the equations 1 and 2 are equal.

  By stopping the motor when the torque T calculated above is equal to or greater than the preset tightening torque setting value, the tightening object will not be damaged or the tightening torque will not be insufficient. Tightening torque T is generated. Further, the motor stop condition for tightening with the torque set value can be set by the number of hits when the motor rotation speed is kept substantially constant.

However, in the above-described conventional impact rotary tool, if used continuously, the hammering torque of the hammer or anvil hits and deforms, so that the impact torque for each impact is reduced, and the tightening torque is lower than at the start of use. There was a problem.
JP 2000-354976 A

  The present invention has been made to solve such a problem, and the impact rotation capable of generating an appropriate tightening torque even if the impact torque changes with time by continuing to use the impact rotating tool. The purpose is to provide a tool.

  In order to achieve the above object, the invention described in claim 1 is an impact rotary tool that generates a tightening torque by rotating a hammer with a motor and applying a hammering torque to the object to be tightened. Torque calculating means for calculating the tightening torque; and torque correcting means for correcting the tightening torque calculated by the torque calculating means by calculating a change over time in the magnitude of the impact torque, and When the tightening torque corrected by the torque correcting means reaches a preset tightening torque set value, the motor is stopped and the tightening target is tightened with the tightening torque set value.

  The invention according to claim 2 is an impact rotary tool that generates a tightening torque by rotating a hammer with a motor and applying a hammering torque to the object to be tightened, and detects hammering of the hammer. An impact detecting means; a speed detecting means for detecting the rotational speed of the motor; and a control means for controlling the motor at a constant speed based on an output of the speed detecting means. Stroke number calculating means for calculating the required number of hits corresponding to the attached torque setting value, and batting for correcting the required hit number calculated by the hit number calculating means by calculating the change with time of the magnitude of the hit torque Number correction means, and a hit number counting means for counting the number of hits from the detection of the hit, the required hit after the hit count counted by the hit number correcting means is corrected by the hit number correction means The motor is stopped when it reaches the one in which tightening the clamping object in the torque setting said clamping.

  According to a third aspect of the present invention, in the impact rotary tool according to the second aspect of the present invention, the impact rotating tool includes a storage unit that stores a cumulative number of hits from the start of use or tightening torque calibration, and the control unit stores the storage unit in the storage unit. In accordance with the increase in the accumulated number of hits stored, the reduction in the hitting torque is calculated to calculate the reduction in the tightening torque, and the required number of hits is corrected.

  According to a fourth aspect of the present invention, in the impact rotary tool according to the second aspect of the present invention, the impact rotating tool includes storage means for storing a total use time from the start of use or tightening torque calibration, and the control means is stored in the storage means. In accordance with the stored increase in the total use time, the decrease in the hitting torque is calculated to calculate the decrease in the tightening torque, and the required number of hits is corrected.

  According to a fifth aspect of the present invention, in the impact rotary tool according to any one of the second to fourth aspects of the present invention, a warning is given to a user when the correction of the required number of hits exceeds a certain level. Means are provided.

  According to a sixth aspect of the present invention, in the impact rotary tool according to any one of the second to fifth aspects, when the correction of the required number of hits increases beyond a certain level, the control unit starts hitting. It is to suppress control.

  According to the first aspect of the present invention, the impact rotary tool corrects the calculated tightening torque even if the impact torque changes with time due to wear of the hammer due to continued use, etc. The tightening target can be properly tightened with a preset tightening torque set value.

  According to the second aspect of the present invention, the impact rotary tool corrects the required number of impacts even if the impact torque changes with time due to wear of the hammer caused by continued use, etc. The object can be properly tightened with a preset tightening torque setting value, and the trouble of recalibrating the torque with respect to changes over time can be eliminated.

  According to the third aspect of the invention, since the required number of hits is corrected by calculating the reduction in the hitting torque due to wear of the hammer from the cumulative number of hits, the control means only includes a storage means for storing the number of hits. This makes it possible to make corrections, and it is possible to tighten with high accuracy at low cost.

  According to the fourth aspect of the present invention, since the reduction in the hitting torque is calculated based on the total usage time and the required hitting number is corrected, the storage in the storage means having a small capacity is required as compared with the case of storing the cumulative hitting number. Therefore, accurate tightening can be performed at a lower cost.

  According to the invention described in claim 5, when the correction of the required number of hits increases beyond a certain level, the impact rotary tool gives a warning to the user, so that it is impossible to tighten at the tightening torque set value. Can be prevented.

  According to the sixth aspect of the present invention, it is possible to prevent a failure in tightening due to the tightening torque not reaching the tightening torque set value.

  Hereinafter, the configuration of the impact rotary tool 1 according to the first embodiment of the present invention will be described with reference to FIG. The electric impact rotary tool 1 includes a motor 2 that is a drive source, a speed reducer 3 that is a transmission mechanism that decelerates rotation of the motor 2 at a predetermined reduction ratio, and rotation of the motor 2 is transmitted via the speed reducer 3. A hammer 4, an anvil 5 struck by the hammer 4, and an output shaft 6 to which torque is applied impactively by the struck are provided. The hammer 4 is struck when a predetermined force or more is applied between the hammer 4 and the anvil 5 and the hammer 4 rotates with respect to the anvil 5 by a certain amount or more. A bit 11 is detachably attached to the output shaft 6 by a chuck 12, and the impact torque of the output shaft 6 is applied to an object to be tightened (not shown) such as a bolt via the bit 11 and tightened. Tightening torque is generated on the object. Speed detecting means 9 comprising a frequency generator that generates a frequency signal proportional to the rotational speed of the motor 2 detects the rotational speed of the motor 2. The speed detection means 9 may be, for example, an encoder or the like. If the motor 2 is a brushless motor, the speed detection means 9 may detect the rotational speed by a Hall sensor signal or a counter electromotive force. For example, the advance angle of the anvil 5 for each impact is calculated from the advance angle of the motor 2 for each impact. The advance angle of the motor 2 is calculated by integrating the rotational speed of the motor 2 over time. The advance angle of the anvil 5 may be detected by providing the anvil 5 with an angle sensor. The impact rotary tool 1 includes a hit detection means 10 for detecting the hit of the hammer 4 and the anvil 5. The hit detection means 10 may detect an impact from, for example, a change in the rotational speed of the motor 2 or may detect the impact with an impact sensor. The motor 2 is connected to a control means 7 comprising a control circuit having a CPU, and the control means 7 performs control such as changing the rotational speed of the motor 2 according to the pull-in size of the trigger 8 operated by the user. . The rechargeable battery 14 supplies power to the impact rotary tool 1.

  Next, control of the tool will be described with reference to FIGS. In FIG. 2, the user of the tool presets the tightening torque setting value 76 of the impact rotary tool 1 in the control means 7 by torque setting means (not shown) such as a variable resistor. When the user pulls the trigger 8, the motor control unit 77 controls the motor 2 so as to rotate at a rotation speed corresponding to how the trigger 8 is pulled. The hit detection unit 72 detects the hit timing based on the output of the hit detection means 10. For each hitting timing detected, the hammer speed detector 71 calculates the speed of the hammer 4 and the advance angle of the anvil 5 from the output of the speed detector 9. Based on the speed of the hammer 4 and the advance angle of the anvil 5 at each hitting timing, the torque calculation unit 75 calculates the tightening torque according to Equation 3 above. The control unit 7 includes a storage unit 73 made of a non-volatile memory such as an EPROM on the control circuit, and stores the total use time from the time of manufacture, that is, the start of use, in the storage unit 73. Due to wear of the hammer 4 and the anvil 5, as shown in FIG. 4, the impact torque τ becomes the initial value as the cumulative impact number or the total work time from the start of use of the impact rotary tool 1 increases. Decreases over time from τ0. When the impact torque τ for each impact decreases, the tightening torque generated even when the object to be tightened is hit the same number of times. In FIG. 4, τ / τ 0 is a correction coefficient due to the change in impact torque with time, the initial value at the start of use is 1, and decreases as the cumulative number of hits or the total work time from the start of use increases. . The torque calculator 75 includes data necessary for calculating the correction coefficient τ / τ0, and calculates the correction coefficient τ / τ0 for the total work time from the start of use stored in the storage unit 73. The torque calculation unit 75 performs correction by multiplying the tightening torque calculated based on the above Equation 3 by the correction coefficient τ / τ0. When the corrected tightening torque reaches the torque set value 76, the motor control unit 77 stops the motor 2, and the impact rotary tool 1 completes the tightening. Thereby, the impact rotary tool 1 can properly tighten the tightening target with the set tightening torque value.

  Next, an impact rotary tool according to a second embodiment of the present invention will be described with reference to FIG. 3 in the configuration shown in FIG. The control means 7 detects the rotation speed of the motor 2 by the hammer speed detection section 71 based on the output of the speed detection means 9, and performs feedback control to rotate the motor 2 at a constant speed by the motor control section 78. In Equation 3 above, if the rotational speed of the motor 2 changes, the angular speed ω of the hammer 4 at the time of impact also changes, and the tightening torque for the same number of impacts changes, so that the motor 2 is controlled at a constant speed. The hit number calculation unit 79 calculates the required hit number according to a preset torque setting value 76. The striking torque τ decreases with time from the initial value τ0. The number-of-strokes calculation unit 79 includes data necessary for calculating the correction coefficient τ / τ0 based on the change with time of the hitting torque, and the correction coefficient τ for the total work time from the start of use stored in the storage unit 73. / τ0 is calculated. The hit number calculation unit 79 performs correction by dividing the required hit number by the correction coefficient τ / τ0. Since the correction coefficient τ / τ0 has an initial value of 1 and decreases with time, this correction increases the required number of hits. The hit number calculation unit 79 counts the hit number from the hit detected by the hit detection unit 72, and when the counted hit number reaches the corrected required hit number, the hit number calculation unit 79 sends a motor control to the motor control unit 78. A stop command is issued, the motor control unit 78 stops the motor 2, and the impact rotary tool 20 completes tightening. Thereby, the impact rotary tool 20 can appropriately tighten the tightening target with the set tightening torque set value. Also, if the required number of impacts is not corrected in this way, it is necessary to recalibrate the required number of impacts with respect to the setting of the tightening torque value as the impact torque changes over time. It gradually decreases. However, since the hit number calculation unit 79 corrects the required hit number, the trouble of recalibrating the torque can be eliminated.

  In the first and second embodiments, the total use time of the impact rotary tool is stored in the storage unit 73, and the control unit 7 performs correction according to the change over time based on the total use time. The correction may be performed based on the cumulative number of hits instead of the total use time. This is because the cumulative number of impacts has a change in impact torque with time similar to the total usage time. However, since the impact rotary tool performs several hundreds of hits per second, the cumulative number of hits becomes a large value compared to the total use time, and the capacity of the storage means 73 necessary for storing the cumulative hit number is large. Therefore, it is preferable to store the total usage time in the storage unit 73. Thereby, accurate tightening can be performed at low cost.

  Furthermore, a warning means (not shown) may be provided in the impact rotary tool 20, and the warning means may give a warning to the user when the correction of the required number of hits performed by the hit number calculation unit 79 has increased beyond a certain level. Thereby, it is possible to prevent in advance that tightening with the set torque cannot be performed. The warning means may be, for example, a visual means using LED light emission or an auditory means using an alarm sound.

  When the correction of the required number of hits by the hit number calculation unit 79 increases to a certain level or more, the control means 7 controls the motor control unit 78 to suppress the start of the motor 2 and to control the start of hitting by the impact rotary tool. Good. When the start of hitting is suppressed, the impact rotary tool 20 does not start hitting even if the user operates the trigger 8. As a result, it is possible to prevent a tightening failure in which the impact rotating tool starts hitting but the tightening torque does not reach the tightening torque set value.

  The present invention is not limited to the configuration of each of the embodiments described above, and various modifications can be made without departing from the scope of the invention. For example, in the impact rotary tool, the motor 2 may be an air motor, and a gas cylinder or a pipe that supplies compressed air from the outside may be provided.

The block diagram of the impact rotary tool which concerns on the 1st Embodiment of this invention. The control block diagram of the tool. The control block diagram of the impact rotary tool which concerns on the 2nd Embodiment of this invention. The figure explaining the time-dependent change of the impact torque with respect to the cumulative impact number or total work time of an impact rotary tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impact rotary tool 2 Motor 4 Hammer 7 Control means 73 Memory | storage means 9 Motor rotational speed detection means 10 Impact detection means 20 Impact rotary tool

Claims (6)

An impact rotary tool that rotationally drives a hammer with a motor and generates a tightening torque by adding a hammering torque to the object to be tightened,
Torque calculating means for calculating the tightening torque;
Torque correction means for correcting the tightening torque calculated by the torque calculation means by calculating a change with time of the magnitude of the impact torque,
When the tightening torque corrected by the torque correcting means reaches a preset tightening torque set value, the motor is stopped and the tightening target is tightened with the tightening torque set value. Impact rotary tool. An impact rotary tool that rotationally drives a hammer with a motor and generates a tightening torque by adding a hammering torque to the object to be tightened,
A hit detecting means for detecting the hit of the hammer,
Speed detecting means for detecting the rotational speed of the motor;
Control means for controlling the motor at a constant speed based on the output of the speed detection means,
The control means is an impact number calculating means for calculating a required impact number according to a preset tightening torque setting value;
By calculating the change over time in the magnitude of the hitting torque, the hit number correcting means for correcting the required hit number calculated by the hit number calculating means,
A striking number counting means for counting the striking number from detection of the striking,
When the number of hits counted by the hit number counting means reaches the required number of hits corrected by the hit number correcting means, the motor is stopped and the tightening target is tightened with the set tightening torque value. Characteristic impact rotary tool. Storage means for storing the cumulative number of impacts from the start of use or tightening torque calibration;
The control means calculates a reduction in the tightening torque by calculating a decrease in the hitting torque in accordance with an increase in the cumulative number of hits stored in the storage means, and corrects the necessary hitting number. The impact rotary tool according to claim 2. Storage means for storing the total use time from the start of use or tightening torque calibration;
The control means calculates a decrease in the tightening torque by calculating a decrease in the impact torque in accordance with an increase in the total use time stored in the storage means, and corrects the required number of impacts. The impact rotary tool according to claim 2.   The impact rotary tool according to any one of claims 2 to 4, further comprising warning means for giving a warning to a user when the correction of the required number of hits exceeds a certain level.   The impact rotary tool according to any one of claims 2 to 5, wherein when the correction of the required number of hits increases beyond a certain level, the control unit controls to stop hitting.

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