JP7030755B2 - Impulse tightening method with optimized rebound - Google Patents

Description

The field of the present invention is the field of impulse type tightening method and impulse type tightening device.

The impulse tightening method is generally used for tightening an assembly to be tightened in various fields such as the automobile industry and the aircraft industry.

Impulse screwdrivers typically include a casing that houses an electric motor with a rotor and stator, at the end of which a tip member that works with the element to be tightened can rotate. It is attached to.

The casing houses a transmission device that connects the rotor to the tip rotating member. Therefore, the transmission device makes it possible to transmit the rotational motion of the rotor to the tip member. The transmission device transmits the mechanical power of the motor to the tip member by reducing the rotation speed. The transmission device can be a planetary gear train having a sun gear that is rotationally driven by a motor, a planetary gear held by a planetary gear carrier, and a ring.

Such a screwdriver is equipped with an angle sensor. The rotor of the angle sensor is connected to the rotor of the motor, and the stator of the angle sensor is connected to the stator of the motor.

Such screwdrivers also include a torque sensor integrated with the transmission. For example, a strain gauge sensor that connects the ring of a planetary gear train to the casing of a screwdriver. The ring is mounted so that it can rotate within the casing and is stopped by a torque sensor.

Transmission devices are usually equipped with functional clearance. This functional clearance is the required clearance by design, in which different components of the transmission, such as different gear devices, move relative to each other to provide rotational movement between the motor and the tip member. Communication is possible.

Given this clearance, the rotor can be positioned as follows.
-Backstop position where the clearance is no longer in the unscrewing sense. The tip member is in a stationary state, and the rotor is stopped in the anti-tightening direction.
-Forward-stop position where the clearance is no longer in the tightening sense. The tip member is in a stationary state, and the rotor is stopped in the tightening direction.

The total functional clearance in the transmission corresponds to these two positions, the rotation angle of the rotor between the front stop position and the rear stop position.

Impulse tightening of an assembly comprises a series of successive tightening cycles that are periodically repeated according to a predetermined frequency.

Each tightening cycle can be divided into four consecutive phases:
-Free acceleration phase of the rotor (no resistance torque) under the influence of power supply to the motor for a period of time during which the rotor absorbs the clearance available in the transmission in the tightening direction.
-In the impact phase, the kinetic energy accumulated by the rotational components in the acceleration phase is transmitted to the tip member, and the tightening target element is tightened. This impact phase begins when the transmission clearance is completely eliminated in the tightening direction (ie, at the end of the preceding step) and continues until the element being tightened is no longer rotationally driven by the tip member.
-A relaxation phase in which the elastically deformed transmission device relaxes and regains its initial shape during the impact phase.
-A rebound phase in which the rotating parts of the screw driver (tip member, transmission and rotor) naturally rebound in the anti-tightening direction when taking in all or part of the functional clearance of the transmission.

The cycle cycle is constant and does not change during the functioning of the tightening tool.

Similarly, the time to power the motor during the acceleration phase of each cycle is constant. Therefore, this time of the motor power supply phase is constant and cannot be changed. Therefore, the time of power supply of the motor is not managed.

Ideally, the rotor under the influence of the rebound should be in the rear stop position at the end of the relaxation and rebound phases where the clearance available in the transmission is maximum in the tightening direction. This allows the rotor to accelerate freely over the angular range corresponding to the overall functional clearance, ensuring optimal operation of the tool.

Therefore, in the relaxation and rebound phases of the cycle, the natural rebound of the motor helps to reset the tool to its initial position, i.e., to return the rotor to its rear stop position.

This natural rebound is possible due to the deformation of internal elements in the tool that behave like torsion springs, primarily the transmission. Therefore, at the end of the impact phase, this spring will have stored potential energy that depends on the following two parameters.
-Rigidity of a set of deforming elements (Nm / degree)
-Torque applied at impact

This stiffness is constant and depends on the tool design (material, shape, size, etc.). By convention, rigidity is evaluated herein according to the torque measured by the torque sensor of the screw driver and the angle measured by the angle sensor coupled to the rotor of the motor. This stiffness is measured in a motor shaft with an output shaft fixed to the casing of the screwdriver.

ただし、
Ｃ_{ｓｅｎｓｏｒ}：トルクセンサによって測定された締付けトルクを表すトルク。
∝_{ｍｏｔｏｒ}：太陽歯車又はドライブシャフトの回転角度。
Ｚ_{ｓｕｎ ｇｅａｒ}：伝動装置の太陽歯車の歯数。
Ｚ_ｒｉｎｇ：伝動装置のリングの歯数。
η_１：ドライブシャフトとリングとの間の伝動効率。 This rigidity K _TR is expressed as follows.

However,
C _sensor : A torque that represents the tightening torque measured by the torque sensor.
∝ _motor : Rotation angle of the sun gear or drive shaft.
Z _{sun gear} : The number of teeth of the sun gear of the transmission device.
Z _ring : The number of teeth in the ring of the transmission device.
η ₁ : Transmission efficiency between the drive shaft and the ring.

The torque applied at impact corresponds to the torque applied to the screw at a given impulse. This torque gradually increases as long as the screw is tightened. Therefore, this torque increases with each impulse (ie, each cycle). This torque is measured when the rotation of the screw, and therefore the rotor of the motor, stops. This torque is indirectly measured by the screwdriver's torque sensor, which is integrated into the screwdriver's mechanical transmission.

ただし、
Ｒ：遊星歯車列の入力太陽歯車と遊星歯車キャリヤとの間の減速比。
η：太陽歯車と遊星歯車キャリヤとの間の伝動効率。

As is known to those skilled in the art, the relationship between the torque C _screw applied to the screw and the torque sensor measured by the _sensor is as follows.

However,
R: Reduction ratio between the input sun gear of the planetary gear train and the planetary gear carrier.
η: Transmission efficiency between the sun gear and the planetary gear carrier.

Therefore, in the tightening operation, it can be seen that the potential energy _ETR stored in the transmission device at the end of the impact increases after each impulse (and therefore, this potential energy increases with each cycle).

This potential energy _ETR is expressed as follows.

After impact, no current is applied to the motor terminals. Therefore, the motor is in freewheel mode (inertial mode). Therefore, the potential energy _ETR stored in the transmission device is converted into the _kinetic energy EC of the rotor under the influence of the relaxation of the transmission device having the conversion efficiency η ₂ .

The kinetic energy _EC of the rotor is expressed as follows.

At the end of the relaxation phase, contact in the transmission chain is lost, subject to rotor recoil and functional clearance of the transmission. When this contact is interrupted, the rotor reaches the initial rotation speed ω _initial .

ここで、Ｊは、回転子の慣性である。 Therefore, if the available potential energy and conversion efficiency to kinetic energy are known, this kinetic energy can be calculated and then the rebound rotation speed can be extracted from this kinetic energy by the following equation.

Here, J is the inertia of the rotor.

ただし、

である。 Therefore, at the end of each cycle, it is possible to calculate the rebound speed of the rotor of the motor, which is likened to its initial rotation speed ω _initial , as follows.

However,

Is.

Therefore, the number of revolutions of the rotor at the end of the relaxation phase of the cycle becomes higher and higher as the tightening torque during this cycle increases.

The angular amplitude of the rotor's rebound first depends on its initial speed and the time given to the rebound in the cycle. The time given to the rebound during a cycle is equal to the elapsed time between the start of the relaxation phase of the cycle and the start of the next cycle.

The time during which power is supplied to the motor and the time during which power is not supplied to the motor in the cycle are fixed. As a result, the time available for rebound is essentially constant from cycle to cycle.

Therefore, since the rebound time is almost constant for each cycle, the rebound angle at which the rotor advances becomes smaller and smaller as the initial rotation speed is smaller.

As a result, at the start of the tightening operation, when the rotor tightening torque and initial speed are small, the rotor rebound angle may also be small in itself, much lower than the maximum acceleration clearance. .. In other words, the functional clearance of the transmission is not completely eliminated by the rotor in the anti-tightening direction. This set of problems with the impulse tightening technique with free rebound of the rotor in each cycle is, of course, the case of the impulse tightening technique with the non-free rotor rebound, which is directed by the reversal of the direction of rotation of the motor. Does not happen.

As a result, in the first cycle with low tightening torque and low rotor rebound, the clearance truly available in the transmission to allow the rotor to accelerate freely is the overall transmission of the transmission. Smaller than functional clearance.

This in particular has the following consequences:
-Since the rotor acceleration stroke is smaller than the normal stroke (maximum angular clearance of the transmission), the kinetic energy stored in the rotor before impact is smaller than normal and therefore the tightening efficiency is reduced.
-The motor's power supply time is constant from cycle to cycle, so the motor's power supply is maintained beyond the impact of the first cycle, where the angular clearance available for the rotor to accelerate freely is small. There is a risk. Prolonging the power supply beyond the impact in this way attenuates the rebound and thus may increase what was pointed out above. Therefore, it is possible that the screwdriver will never reach the optimum functional state.
-In addition, the motor's power supply expands at impact, while there is no longer any clearance that allows the motor to accelerate freely, so the motor has a fixed point of rotation speed assigned to itself by the controller. The value can no longer be reached. This results in overcurrent and fails the screwdriver when the maximum strength programmed by security in the controller is exceeded. If the system fails in this way, it will require technician action to repair it. This impairs productivity and is therefore undesirable.

One way to avoid these cases where the current consumption limit is exceeded is to reduce the motor power supply time. However, this solution reduces the performance of the tool when the rebound is greater and is therefore unsatisfactory.

Therefore, even if the impulse screwdrivers are generally satisfactory, their operation can be further improved.

It is an object of the present invention, in particular, to provide an efficient solution to at least some of these various problems.

In particular, according to at least one embodiment, an object of the present invention is to optimize impulse tightening.

In particular, it is an object of the present invention to provide this type of technique that, according to at least one embodiment, maintains optimum tightening performance essentially throughout the tightening of the assembly by impulse tightening.

Another object of the invention is to provide, according to at least one embodiment, a technique of this kind that prevents motor power supply from continuing beyond the impact phase during a cycle.

Another object of the present invention is to provide this kind of technique for avoiding overcurrent in motor power supply, according to at least one embodiment.

Another object of the invention is to provide this kind of technique that, according to at least one embodiment, is reliable and / or robust and / or simple to implement.

To this end, the present invention is:
Motors with rotors and stators,
A rotary output member (also called a tip member) that cooperates with the element to be tightened,
It is a transmission device for connecting the rotor to the output member, and is a method of tightening with an impulse type screw driver including a transmission device having a functional clearance.
Includes a series of basic tightening cycles according to a given frequency
Each of the above tightening cycles
A step of supplying electric power to the motor and rotationally driving the rotor in the tightening direction,
Obtaining information representing the angular position of the rotor in real time,
An impact step in which the torque impulse is transmitted to the rotary output member, which starts when the functional clearance of the transmission device is removed in the tightening direction and stops rotating in the tightening direction. The impact step to end and
We propose a method including a free rebound step in which the rotor freely rebounds in the anti-tightening direction.

According to the present invention, each cycle further includes a step of obtaining information representing the final angular position of the rotor at the end of the impact step, and the power supply step of a given tightening cycle is based on the rotor. Therefore, it is carried out until the final angle position that was located in the immediately preceding tightening cycle is reached.

Therefore, according to the present invention, in the impulse tightening operation, each cycle includes free rebound of the motor after impact. In one cycle, powering the motor is essentially continued until the rotor occupies the angular position at the end of the impact step of the previous cycle.

Thus, according to the method of the present invention, if necessary, after a short transient operating state, the following stable operating state operation is brought about.
-The functional clearance of the transmission is fully captured by the rotor at each free rebound. Then, the rotor can be freely accelerated over the entire functional clearance in the next acceleration phase, and the optimum impact phase is secured in each cycle.
-Powering to the motor does not continue with the relaxation of the transmission and the rebound of the rotor. Therefore, the above problems are prevented from occurring, and the risk of overcurrent in the power supply and the risk of system incapacity are prevented.

Therefore, the method according to the present invention guarantees the realization of an optimized free rebound type impulse tightening of the rotor.

According to one variant, the power supply step of the given tightening cycle is at an angular position that is a predetermined value behind the final angular position that the rotor was located during the previous tightening cycle. It will be carried out until it is located.

According to one variant, the power supply step of the given tightening cycle is at an angular position that is a predetermined value behind the final angular position that the rotor was located during the previous tightening cycle. It will be carried out until it is located.

According to one variant, each of the tightening cycles comprises a step of detecting a rotational reversal of the rotor during the cycle. When the reversal of the rotation direction of the rotor is detected in a certain tightening cycle, a step of obtaining information representing the final angular position of the rotor is performed in the tightening cycle.

According to one variant, each of the tightening cycles comprises a step of seeking information representing the free rebound angle of the rotor in the free rebound step. The power supply step of the given tightening cycle is carried out until the rotor advances in the tightening direction over an angle substantially equal to the free rebound angle of the rotor during the previous tightening cycle.

According to one variant, each of the tightening cycles includes a step of determining the free rebound speed of the rotor and a step of determining the free rebound time of the rotor. Information representing the free rebound angle of the rotor is obtained according to the free rebound speed and the free rebound time of the rotor.

According to one variant, each tightening cycle includes a step of determining the tightening torque reached at the end of the impact step. The free rebound speed of the rotor is obtained according to the tightening torque, the rigidity of the transmission device, and the ratio of the transmission device.

According to one variant, each tightening cycle includes a step of determining the elapsed time from the start of the power supply step to the end of the impact step. The free rebound step is performed at a time equal to a predetermined time subtracted by the elapsed time.

The present invention also
Motors with rotors and stators,
Rotational output members designed to work with the elements to be tightened,
A transmission device that connects the rotor to the output member and has a functional clearance.
A means for obtaining information representing the angular position of the rotor in real time,
Equipped with a command means to carry out a series of basic tightening cycles according to a predetermined frequency,
Each of the above tightening cycles
A step of supplying electric power to the motor and rotationally driving the rotor in the tightening direction,
Obtaining information representing the angular position of the rotor in real time,
An impact step in which the torque impulse is transmitted to the rotational output member, which starts when the functional clearance of the transmission device is removed in the tightening direction and ends when the rotational output member stops rotating in the tightening direction. Impact step and
At the end of the impact step, a step to obtain information indicating the final angular position of the rotor, and a step to obtain information.
Including the free rebound step in which the rotor freely rebounds in the anti-tightening direction.
The power supply step for a given tightening cycle relates to an impulse tightening device, which is performed until the rotor is essentially at the final angular position where it was located in the previous tightening cycle.

According to one variant, the power supply step of the given tightening cycle is at a predetermined angular position ahead of the final angular position where the rotor was located in the previous tightening cycle by a predetermined value. The above-mentioned command means is configured so as to be performed until it becomes.

According to one variant, the power supply step of the given tightening cycle is performed until the rotor is at an angular position a predetermined value behind the final angular position where the rotor was located in the immediately preceding tightening cycle. The above-mentioned command means is configured.

According to one variant, the device according to the invention comprises means for detecting a rotational reversal of the rotor in a cycle. The command means is configured such that each of the tightening cycles comprises a step of detecting a rotational reversal of the rotor in the cycle. When the reversal of the rotation direction of the rotor is detected in the tightening cycle, a step of obtaining information representing the final angular position of the rotor is performed in the tightening cycle.

According to one variant, the command means is configured to seek information representing the free rebound angle of the rotor in the free rebound step in each tightening cycle. The power supply step of the given tightening cycle is carried out until the rotor advances in the tightening direction over an angle substantially equal to the free rebound angle of the rotor in the previous tightening cycle.

According to one variant, the device according to the invention comprises means for obtaining information representing the free rebound speed of the rotor. Each of the tightening cycles is configured to include a step of determining the free rebound speed of the rotor and a step of determining the free rebound time of the rotor. Information representing the free rebound angle of the rotor is obtained according to the free rebound speed and the free rebound time of the rotor.

According to one variant, the device according to the invention comprises means for measuring information representing tightening torque. The command means is configured to include a step of determining the tightening torque that each tightening cycle reaches at the end of the impact step. The free rebound speed of the rotor is obtained according to the tightening torque, the rigidity of the transmission device, and the ratio of the transmission device.

According to one variant, the directive is configured to determine the elapsed time from the start of the power supply step to the end of the impact step in each tightening cycle. The free rebound step is performed for a period of time equal to a predetermined time minus the elapsed time.

Other features and advantages of the present invention will be apparent from the following description and accompanying figures of the particular embodiments given as mere examples and non-exhaustive examples.

It is a partial cross-sectional side view of an example of an impulse type screwdriver by this invention. It is a figure which shows an example of the controller of the screwdriver of FIG. It is a flowchart which shows an example of the impulse type tightening method by this invention. It is a flowchart which shows another example of the impulse type tightening method by this invention. From the transient functional state in which the free acceleration angle range of the rotor gradually increases with each cycle and approaches the functional clearance of the transmission, the angle range of the free acceleration of the rotor becomes the functional clearance of the transmission in each cycle. It is a figure which shows the transition to the equal stabilization work state.

[1. architecture]
With reference to FIGS. 1 and 2, an example of a tool according to the present invention, in this embodiment, an impulse screwdriver, also referred to as a pulse mode screwdriver, is shown.

The screwdriver preferably comprises a body 1 having the shape of a pistol and having a grip 2. The main body may have a shape extending along the axis as an alternative form instead of the shape of a pistol. An electric motor 3 is housed in the main body 1.

The motor 3 is preferably a permanent magnet synchronous motor. However, this motor can be, for example, any other type of electric motor adapted to DC current. This motor includes a stator 31 and a rotor 32.

The rotor 32 is connected to the tip member 4 capable of rotational drive via a transmission device T. The tip member 4 is designed to work directly or with a sleeve with a tightening element such as a screw or nut.

In this embodiment, the transmission device comprises a single planetary gear train 7. In this gear train, the sun gear 71 is fixedly attached to the shaft 33 so as to rotate together with the shaft 33 of the rotor 32 of the motor 3. The planetary gear 72 of this gear train is attached so as to be able to rotate around a pin 73 fixedly attached to the planetary gear carrier 74. The planetary gear carrier 74 is fixedly attached to the tip member 4 so as to rotate together with the tip member 4. The transmission device can also include a plurality of planetary gear trains.

The screwdriver comprises a torque sensor 8 used to measure information representing the tightening torque.

The ring 9 of the planetary gear train 7 is connected to the main body 1 of the screwdriver by a deforming element that prevents the ring from rotating in the main body. This deforming element, which partially constitutes the torque sensor 8, holds a strain gauge and deforms according to the tightening torque. This torque sensor is used to measure the reaction torque of the ring during the tightening operation. This reaction torque corresponds to the tightening torque.

The screw driver comprises an angle sensor 10 used to measure information representing the angle of rotation between the rotor and stator of the motor.

The transmission has a functional clearance, i.e., the mechanical clearance required for the assembly and the stress-free relative motion of the various parts that make up the transmission. Given this clearance, the rotor of the motor
-The maximum bounce position, that is, the rear stop position, where the clearance is the maximum in the tightening direction,
-Can move between the impact position where the clearance disappears in the tightening direction, that is, the forward stop position.

At the maximum bounce position, the output shaft (or tip member) and grip of this screwdriver are fixed, and the rotor of the motor is fixed at the stop position in the transmission device at the end of rotation in the opposite direction of tightening, and this transmission device Obtained when the clearance of is taken in.

The impact position is obtained when the output shaft and grip of this screwdriver are fixed, the rotor of the motor is fixed at the stop position in the transmission device at the end of rotation in the tightening direction, and the clearance of the transmission device is taken in. Be done.

The screwdriver comprises an actuating trigger 11 that allows the operator to initiate a tightening operation.

The screw driver 1 includes a command means such as a controller 17. The controller 17 may be provided inside the tool or may be provided outside. This controller allows the tool to be controlled to implement a pre-programmed tightening or drilling policy.

If not integrated within the tool, the controller is connected to the tool by wired or non-wired means (eg, wireless).

When the tool is connected to the controller by one or more cables, the controller allows the tool to be energized in a manner known per se.

For wireless tools, the power source for this tool can include one or more batteries.

The controller 17 includes, for example, a processing unit 170 with a microprocessor, random access memory 171 and a computer program comprising program code instructions that perform a tightening or drilling method, or more generally a method according to the invention. A read-only memory 172 is particularly provided.

The means required to carry out the method according to the invention can be integrated into a tool or a controller.

The controller comprises a wireless transmit / receive module 173 that allows communication with the tool if it is not connected to the tool by a cable.

Whether wired or not, the controller communicates between the tool and the controller.
Receiving signals sent from various measuring means (sensors) integrated with the tool,
You can send commands to the tool.

The controller can communicate with other devices such as computer networks by wired means.

The tool also includes a transmit / receive module 18 that communicates with the controller.

The controller manages the command input means 175 (keyboard, touchpad screen, mouse, etc.), the display means 176 (screen, display device, indicator light), and in some cases, the means 177 that outputs an audible frequency acoustic signal. It also includes an input / output interface 174, which is a user interface, and a connector 178 for power supply.

The controller also includes an inverter 179 that supplies power to the motor means.

As described in more detail below, the controller (command means) is programmed to implement the impulse tightening method.

[2. Tightening method]
[2.1. First method]
Subsequently, an example of the impulse type tightening method according to the present invention will be described with reference to FIG.

The tightening operation includes the pre-tightening phase 40 performed before the tightening phase 41 as before. Of course, it is not necessary to carry out the pre-tightening treatment phase 40.

In the tightening pretreatment phase 40, power is supplied to the motor to obtain rotation of the motor at a continuous speed (step 401).

In the tightening pretreatment phase, step 402 of measuring at least one piece of information representing the tightening torque is preferably performed continuously in real time. In this step, for example, the tightening torque can be measured by a torque sensor provided in the transmission device.

The measured torque is compared in real time with a predetermined pre-tightening torque threshold corresponding to the torque at the end of the pre-tightening process (step 403).

The motor is powered until the measured tightening torque reaches a predetermined torque threshold at the end of the pre-tightening process.

When this condition is satisfied, the power supply to the motor is stopped and the time T1 is recorded by the controller 17 (step 404).

Subsequently, the tightening step 41 starts.

In the tightening step 41, the motor is powered by an electric impulse. The tightening phase then includes a plurality of basic tightening cycles that are repeated at a predetermined frequency until the assembly is tightened to the desired target torque. Therefore, the motor is supplied with power by a pulse. The time separating two consecutive pulses is a predetermined time P.

A tightening preparation cycle is performed before the first basic tightening cycle.

This tightening preparation cycle includes the rebound step 410. In fact, at the end of the pre-tightening treatment phase, the transmission relaxes and the rotor of the motor naturally rebounds in the anti-tightening direction, at least partially capturing the functional clearance of the transmission, approaching or approaching the rear stop position. To reach.

In the rebound step, the controller allows the rotor to rebound freely. That is, in the absence of power supply to the motor, the rotor shifts in the counter-tightening direction toward the rear stop position while a predetermined time empirically determined elapses after the time T1 (step 411).

After this predetermined time has elapsed, the controller records the time T2 (step 412).

Next, the free acceleration step 413 is performed. In the free acceleration step 413 of the rotor, the motor is powered for a predetermined period of time (step 414). This time is predetermined in the trial (ie, the relaxation and rebound steps) to ensure that the motor power supply does not continue beyond the next impact step.

When the available functional clearance of the transmission is exhausted in the tightening direction, the impact step 415 in which the tip member transmits torque to the element to be tightened begins.

In the impact step 415, a step of detecting the end of the impact is performed. This detection step, here, includes a step of detecting that the rotor has reached its maximum angle. This step can be, for example, to detect when the number of revolutions of the rotor changes its sign. When the maximum angle is detected, this value is recorded (step 416 of detection and recording). This maximum angle is here the absolute angle given by the angle sensor of the motor. This maximum angle is counted from any invariant position and characterizes the angular position of the rotor at the onset of relaxation.

The step of obtaining information representing the tightening torque is performed in real time. At the end of the impact step 415, i.e., at the end of the impact step detection 416, the torque information is recorded as equal to the tightening torque at the end of the impact (step 417). This is the tightening torque measured by the torque sensor when the end of impact is detected.

The torque at the end of impact is compared to the target torque threshold, i.e., the desired torque for tightening the element to be tightened (step 418).

If the torque at the end of impact is equal to or greater than the target torque, in principle, this does not apply at the end of the tightening preparation cycle, and this process ends.

If the torque at the end of impact is less than the target torque threshold, the transmission relaxes and then the rotor rebounds in rebound step 419.

The controller allows the rotor to freely rebound after time T2 (ie, the start of the most recent power supply of the motor) until time P elapses (step 420).

At the end of the free rebound step (ie, at the end of this time) (step 420), the controller records a new time T2 (step 421).

Next, the free acceleration step 422 of the rotor is performed. In this free acceleration step, the motor is powered until the rotor is in the position it was in at the end of the previous impact step 416 (step 423). In other words, the motor is powered in free acceleration step 422 until it reaches the maximum angle at the end of the impact of the previous cycle.

Next, the impact step 415 is newly performed. In this step, step 416 of detecting and recording the maximum impact end angle is performed.

Step 417 to record the tightening torque at the end of impact and step 418 to compare this value with the target tightening torque threshold are performed.

Unless the target tightening torque is reached, the free rebound step 420, the step 421 to record the time T2, the free acceleration step 422, the impact step 415, the torque recording step 417 at the end of impact, and this torque are referred to as the target tightening torque. A new step 418 for comparison is performed.

When the target tightening torque is reached at the end of the impact step 415, the tightening operation ends.

Step 412 recording time T2, free acceleration step 413, as well as first impact step 415, first recording step 417, first comparison step 418, and first rebound step 420 constitute a preparatory cycle. ..

When the preparation cycle is completed, each basic cycle has a predetermined target of step 421 to record the time T2, free acceleration step 423, impact step 415, and step 417 to record the tightening torque at the end of the impact. Includes step 418 for comparison with the tightening torque threshold and free rebound step 420.

The basic cycle continues until the target tightening torque is reached at the end of the impact step.

The cycle that reaches the target tightening torque is the final basic cycle. This final basic cycle ends at the end of comparison step 418 and therefore does not include subsequent steps.

[2.2. Second method]
A second embodiment of the impulse type tightening method according to the present invention will be described with reference to FIG.

The main differences between the second embodiment and the first embodiment will be described below.

The method according to the second embodiment is the same as the method according to the first embodiment until the end of the free acceleration step 413 of the preparation cycle.

In the impact step 415 following the free acceleration step 413, the maximum impact end angle is detected but not recorded (step 416').

After the maximum impact end angle is detected (step 416'), the impact end tightening torque is recorded with time T3.

Next, in step 418, the tightening torque at the end of impact is compared with the target tightening torque threshold. When it is detected in step 418 that the tightening torque at the end of impact is smaller than the target tightening torque threshold value, the method proceeds to the step of obtaining the rebound angle of the rotor.

In the present embodiment, the step of obtaining the rebound angle of the rotor includes the step 50 of obtaining the rebound speed of the rotor.

ただし、

であるとともに、以下の通りである。
Ｃ_{ｓｅｎｓｏｒ}：トルクセンサによって測定されたトルク。
Ｚ_{ｓｕｎ ｇｅａｒ}：伝動装置の太陽歯車の歯数。
Ｚ_ｒｉｎｇ：伝動装置のリングの歯数。
η_１：モータシャフトとリングとの間の伝動効率。
η_２：伝動装置の変形ポテンシャルエネルギーを回転子の運動エネルギーに変える変換効率。
Ｊ：回転子の慣性。
Ｋ_ＴＲ：伝動装置の剛性。 In this step 50, the controller obtains the rebound speed ω _initial of the rotor as follows.

However,

At the same time, it is as follows.
C _sensor : Torque measured by a torque sensor.
Z _{sun gear} : The number of teeth of the sun gear of the transmission device.
Z _ring : The number of teeth in the ring of the transmission device.
η ₁ : Transmission efficiency between the motor shaft and the ring.
η ₂ : Conversion efficiency that converts the deformation potential energy of the transmission device into the kinetic energy of the rotor.
J: Inertia of the rotor.
K _TR : Rigidity of the transmission device.

In step 51, the controller finds the remaining rebound time. This remaining rebound time is equal to P- (T3-T2), which is the result of subtracting the elapsed time between times T2 and T3 from the time P for powering the motor.

In this calculation, the time of relaxation from T3 to the start of rebound is considered negligible.

Next, in step 52, the controller obtains the rebound angle of the rotor from the rebound speed of the rotor and the remaining rebound time (the remaining angle of the rebound = the rebound speed multiplied by the remaining rebound time).

The controller then compares the rebound angle to the functional clearance of the transmission in step 53.

If the rebound angle is less than the functional clearance of the transmission, the method proceeds to rebound step 54. In this step, the rotor naturally returns to its rear stop position in the counter-tightening direction with the passage of time equivalent to the cycle time P from the recording of the previous time T2 (step 541).

At the end of this lapse of time, a new time T2 is recorded in step 55.

Next, a free acceleration step 56 in which electric power is supplied to the motor is performed (step 56). This is done until the rotor rotates by an angle equal to the already calculated rebound angle.

If it is detected in step 53 that the rebound angle is compared with the functional clearance of the transmission device that the rebound angle is equal to or greater than the functional clearance, the process proceeds from step 53 to rebound step 54'. In this step, the rotor naturally returns to its rear stop position in the counter-tightening direction with the passage of time equivalent to the cycle time P from the recording of the previous time T2 (step 541').

At the end of this lapse of time, a new time T2 is recorded in step 55'.

Subsequently, the free acceleration step 56'is performed. In this step, the motor is powered until the rotor rotates by an angle equal to the functional clearance of the transmission (step 562).

Following the rebound step 56 or 56', a new impact step 415 is performed. In this step, the maximum impact end angle is detected, and then step 417 is performed to record the impact end tightening torque and the new time T3.

The end-impact torque is compared to the target tightening torque threshold (step 418).

When the torque at the end of impact reaches the target tightening torque threshold, the tightening operation ends. Otherwise, the process proceeds to a new step 50 for determining the rebound speed of the rotor, and the subsequent steps are continued until the target tightening torque is reached.

Step 412 to record the time T2, free acceleration step 413, first impact step 415, first recording step 417, first comparison step 418, first rebound speed determination step 50, and first rebound rest. Step 51 for obtaining the time, step 52 for obtaining the first rebound angle, step 53 for comparing the first rebound angle with the functional clearance of the transmission device, and the first rebound steps 54 and 54'conform a preparation cycle. do.

When the preparation cycle is completed, each basic cycle records the time T2 at steps 55 and 55', the free acceleration steps 56 and 56', the impact step 415, and the tightening torque at the end of the impact and the time T3 at step 417. Step 418 to compare this value with a predetermined threshold of the target tightening torque, step 50 to obtain the rebound speed, step 51 to obtain the remaining rebound time, step 52 to obtain the rebound angle, and a transmission device for the rebound angle. Includes step 53 and rebound steps 54, 54'compared to the functional clearance of.

The basic cycle continues until the target tightening torque is reached at the end of the impact step.

The cycle that reaches the target tightening torque is the final basic cycle. This final basic cycle ends at the end of comparison step 418 and therefore does not include subsequent steps.

[2.3. advantage]
In both the first and second embodiments, the method according to the invention involves the step of powering the motor in a given tightening cycle, where the motor is essentially at the final angular position in the previous tightening cycle. The main thing is to do it until it becomes.

As described above, according to the method according to the present invention, the following stable operation can be quickly reached.
-The functional clearance of the transmission is fully captured by the rotor during each free rebound. Then, the rotor can freely accelerate in the entire functional clearance in the next acceleration phase, and the optimum impact phase is secured.
-During the relaxation of the transmission and the rebound of the rotor, the power supply to the motor does not continue.

This can be clearly seen from FIG.

As shown in FIG. 5, in the first cycle, the rotor accelerates only in a part of the functional clearance. In fact, the rotor is reaccelerating while the transmission clearance has not yet been compensated for as a whole in the anti-tightening direction. Therefore, the rotor is not in the rear stop position, and the remaining clearance 5 remains in the anti-tightening direction in the transmission device.

Since the angular movement of the rotor acceleration in the first cycle is small, the impact phase is shortened, and so is the relaxation phase and the subsequent rebound phase.

Next, in each subsequent cycle, it can be seen that power is supplied to the motor during the acceleration phase and at the beginning of the impact phase until it reaches the angular position at the end of the impact phase of the previous cycle.

According to this embodiment, as can be seen from FIG. 5, in each cycle, the rate at which the functional clearance of the transmission device is taken up during the rebound of the rotor can be increased.

Therefore, at the end of the fifth rebound cycle, the functional clearance of the transmission is completely removed in the anti-tightening direction and the rotor is in the rear stop position.

As a result, from the sixth basic cycle, the rotor is free to accelerate in the entire functional clearance in each cycle, so that the optimum impact step is ensured.

Therefore, in the impulse tightening, between the 5th cycle and the 6th cycle, the rotor accelerates only in a part of the functional clearance in each cycle, and the angle of free rebound of the rotor changes from cycle to cycle. From the transient state, the rotor accelerates in each cycle over the entire functional clearance, and the rotor rebound angle is approximately the same in each cycle, transitioning to a stable state that is substantially equal to the clearance of the transmission.

Thus, the tightening method according to the invention includes a transitional phase followed by a permanent phase. Each of these two phases involves a series of basic tightening cycles according to a given frequency. In the transient phase, the free rebound angle of the rotor changes from cycle to cycle until the transmission clearance is reached. On the other hand, in the stable phase (permanent phase), the rebound angle of the rotor is about the same in each cycle, which is substantially equal to the clearance of the transmission device.

Further, since the power supply phase continues only until the rotor is in a basic cycle at the end of the impact step of the previous basic cycle, the implementation of the present invention allows the transmission to relax and the rotor. It is ensured that the power supply to the motor is stopped during the rebound. This can ensure that the rotor returns to the rear stop position at the end of each basic cycle. Therefore, the rotor is not braked by the motor during rebound and is guaranteed to return to the rear stop position, allowing acceleration over the overall functional clearance in the next cycle.

Therefore, the method according to the present invention makes it possible for impulse tightening to reach the optimum stable functional state stepwise and quickly.

Claims (16)

Motors with rotors and stators,
A rotary output member that cooperates with the element to be tightened,
A method in which the rotor is connected to the output member and tightened using an impulse screwdriver equipped with a gear transmission device having a functional clearance between the components .
Includes a series of basic tightening cycles according to a given frequency
Each of the tightening cycles
A step of supplying electric power to the motor and rotationally driving the rotor in the tightening direction,
The step of obtaining information representing the angular position of the rotor in real time, and
It is an impact step in which the torque impulse is transmitted to the rotation output member, and starts when the functional clearance of the gear transmission device disappears in the tightening direction and ends when the rotation of the rotation output member in the tightening direction stops. Impact step and
Including a free rebound step in which the rotor freely rebounds in the anti-tightening direction due to the functional clearance .
Each cycle further comprises a step of seeking information representing the final angular position of the rotor at the end of the impact step.
A method in which power is supplied in a given tightening cycle until the rotor is at the final angular position at the end of the impact step in the immediately preceding tightening cycle. The method of claim 1, wherein power is supplied in a given tightening cycle until the rotor is at an angular position a predetermined value ahead of the last angular position of the previous tightening cycle. According to claim 1, the power supply in a given tightening cycle is performed until the rotor is at an angular position a predetermined value behind the final angular position at the end of the impact step in the immediately preceding tightening cycle. The method described. Each of the tightening cycles comprises a step of detecting a rotational reversal of the rotor in the cycle.
One of claims 1 to 3, wherein when the rotation direction reversal of the rotor is detected in a certain tightening cycle, a step of obtaining information representing the final angular position of the rotor is performed in the tightening cycle. The method according to item 1. Each of the tightening cycles comprises a step of seeking information representing the free rebound angle of the rotor in the free rebound step.
One of claims 1 to 3, wherein power is supplied in a given tightening cycle until the rotor advances in the tightening direction over an angle approximately equal to the free rebound angle of the rotor in the previous tightening cycle. The method described in the section. Each of the tightening cycles includes a step of determining the free rebound speed of the rotor and a step of determining the free rebound time of the rotor.
The method according to claim 5, wherein the information representing the free rebound angle of the rotor is obtained according to the free rebound speed and the free rebound time of the rotor. Each tightening cycle includes a step of determining the tightening torque obtained at the end of the impact step.
The method according to claim 6, wherein the free rebound speed of the rotor is obtained according to the tightening torque, the rigidity of the gear transmission device, and the ratio of the gear transmission device. Each tightening cycle includes a step of determining the elapsed time from the start of power supply to the end of the impact step.
The method according to any one of claims 1 to 7, wherein the free rebound step is performed at a time equal to a predetermined time minus the elapsed time. Motors with rotors and stators,
A rotary output member that cooperates with the element to be tightened,
A gear transmission device that connects the rotor to the output member and has a functional clearance between the components .
A means for obtaining information representing the angular position of the rotor in real time,
An impulse-type tightening device equipped with a command means for performing a series of basic tightening cycles according to a predetermined frequency.
Each of the tightening cycles
A step of supplying electric power to the motor and rotationally driving the rotor in the tightening direction,
The step of obtaining information representing the angular position of the rotor in real time, and
It is an impact step in which the torque impulse is transmitted to the rotation output member, and starts when the functional clearance of the gear transmission device disappears in the tightening direction and ends when the rotation of the rotation output member in the tightening direction stops. Impact step and
A step of obtaining information representing the final angular position of the rotor at the end of the impact step, and a step of obtaining information.
Including a free rebound step in which the rotor freely rebounds in the anti-tightening direction due to the functional clearance .
An impulse-type tightening device in which power is supplied in a given tightening cycle until the rotor reaches the final angular position at the end of the impact step in the previous tightening cycle. The command means is configured such that power is supplied in the given tightening cycle until the rotor is at a predetermined angular position ahead of the final angular position of the previous tightening cycle by a predetermined value. The device according to claim 9. The command means is configured such that the power supply in the given tightening cycle is performed until the rotor is at an angular position a predetermined value behind the final angular position of the previous tightening cycle. Item 9. The device according to item 9. A means for detecting the inversion of the rotation direction of the rotor in the cycle is provided.
The command means is configured such that each of the tightening cycles comprises a step of detecting a rotational reversal of the rotor in the cycle.
One of claims 9 to 11, wherein when the rotation direction reversal of the rotor is detected in a certain tightening cycle, a step of obtaining information representing the final angular position of the rotor is performed in the tightening cycle. The device according to item 1. The command means obtains information representing the free rebound angle of the rotor in the free rebound step in each tightening cycle.
One of claims 9-12, wherein power is supplied in a given tightening cycle until the rotor advances in the tightening direction over an angle approximately equal to the free rebound angle of the rotor in the previous tightening cycle. The device described in the section. A means for obtaining information indicating the free rebound speed of the rotor is provided.
The command means is configured such that each of the tightening cycles includes a step of determining the free rebound speed of the rotor and a step of determining the free rebound time of the rotor.
The device according to claim 13, wherein the information representing the free rebound angle of the rotor is obtained according to the free rebound speed and the free rebound time of the rotor. Equipped with means to measure information representing tightening torque
The command means is configured such that each tightening cycle comprises a step of determining the tightening torque obtained at the end of the impact step.
The device according to claim 14, wherein the free rebound speed of the rotor is obtained according to the tightening torque, the rigidity of the gear transmission device, and the ratio of the gear transmission device. The directive determines the elapsed time from the start of power supply to the end of the impact step in each tightening cycle.
The device according to any one of claims 9 to 15, wherein the free rebound step is performed at a time equal to a predetermined time minus the elapsed time.

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