Flexible control method for reverse thrust of electric torque wrench

Abstract

The invention discloses a reverse thrust flexible control method for an electric torque wrench. The electric wrench aims at solving the problem that when a screw is close to a screwing end point, torque is suddenly increased, and consequently the using comfort of the electric wrench is poor. The control method comprises the steps that an acceleration sensor used for measuring the corresponding acceleration of a wrench handle is arranged at the wrench handle; setting tactile response time T of the human body responding to the counter force of the wrench; the wrench controller obtains a signal value m output by the acceleration sensor in real time; and the wrench motor driving current I is correspondingly adjusted within the tactile response time T according to the current change rate correspondingly matched with the signal value m output by the acceleration sensor. By means of the control method, the counter force borne by the electric wrench at the screwing end point can be effectively reduced, and the using comfort of the wrench is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electric wrenches, and in particular to a method for flexible control of reverse thrust of an electric torque wrench. Background Art

[0002] Electric wrenches reduce the labor intensity of manual labor and greatly improve production efficiency. When using an electric wrench, the operator needs to hold the wrench handle to form a balance with the reverse thrust of the electric wrench drive motor to fix the position of the wrench and tighten the screws.

[0003] The tightening process of the screw is the process in which the speed of the electric wrench driving motor changes from high to low. The torque of the wrench increases from small to large in this process. However, the torque change is not uniform during the whole process. When the screw is initially tightened, the resistance of the screw is extremely small, the driving motor is close to no-load, the torque is extremely small, and the directional thrust of the electric wrench is also very small. When the screw is screwed in and approaches the end position, the speed of the screw is instantly reduced from high speed to near zero speed, and the torque increases sharply, which causes the reverse thrust of the wrench to rise sharply, generating a large recoil. When the operator grips the wrench, he often does not have time to predict and respond to the force application, which makes the recoil cause great discomfort to the operator, causing impact on the wrist, and in severe cases may cause personal injury.

[0004] The information disclosed in this background technology section is only used to deepen the understanding of the background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0005] In view of at least one of the above technical problems, the present disclosure provides a method for controlling the reverse thrust flexibility of an electric torque wrench, aiming to solve the problem of poor comfort in using the electric wrench due to a sudden increase in torque when the screw approaches the end point of tightening.

[0006] According to one aspect of the present disclosure, a method for controlling the reverse thrust flexibility of an electric torque wrench is provided, which mainly comprises the following steps: (1) An acceleration sensor is provided at the wrench handle to measure the acceleration corresponding to the wrench handle; and the tactile reaction time of the human body in response to the reaction force of the wrench is set. T ; (2) The wrench controller obtains the signal value output by the acceleration sensor in real time m ; (3) Adjusting the wrench motor drive current within the tactile response time T according to the current change rate corresponding to the signal value m output by the acceleration sensor I .

[0007] In some embodiments of the present disclosure, the acceleration sensor is arranged along the sweeping direction of the wrench handle under the action of the reaction force.

[0008] In some embodiments of the present disclosure, the tactile reaction time T It is 200ms~600ms.

[0009] In some embodiments of the present disclosure, the controller has a tactile reaction time. T Inner t The sampling period corresponds to the signal value of the sampling acceleration sensor, and t Adjust the wrench motor drive current accordingly to the cycle.

[0010] In some embodiments of the present disclosure, each sampling period is calculated separately t The signal change rate within K , the current change rate and signal change rate K Proportional relationship.

[0011] In some embodiments of the present disclosure, the wrench motor driving current in period t I=-ki+b ;in, i is the final value of the current in the previous adjustment cycle, the initial cycle i is the driving current value when the wrench is normally tightened, b is a constant, k is the absolute value of the current change rate.

[0012] In some embodiments of the present disclosure, the current change rate k=cn ,in, c is a constant, n=k max m / m max , m max is the maximum signal value of the acceleration sensor, k max The ratio of the maximum current rise rate of the driving motor.

[0013] One or more technical solutions provided in the embodiments of the present application have at least any of the following technical effects or advantages: The acceleration sensor senses the amplitude of the electric wrench's movement due to the reverse torque, and then adjusts the drive current of the drive motor according to the acceleration of the wrench handle. This reduces the drive current of the drive motor when the wrench handle accelerates, thereby reducing the reverse torque and improving the comfort of using the electric torque wrench. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Picture 1 This is a control principle diagram of a reverse thrust flexibility control method in one embodiment of the present application. DETAILED DESCRIPTION

[0015] The programs involved or relied upon in the following embodiments are all conventional programs or simple programs in the technical field, and those skilled in the art can make conventional selections or adaptive adjustments according to specific application scenarios.

[0016] In order to better understand the technical solution of the present application, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0017] In order to solve the problem that when the existing electric torque wrench approaches the end position of the screw, the wrench handle has a tail sweep phenomenon due to the reverse torque, which causes discomfort in the screwing operation and even causes physical damage to the operator, this example discloses a reverse thrust flexible control method for the electric torque wrench to reduce the reverse torque of the electric torque wrench and reduce or avoid the tail sweep problem of the wrench handle. The control method specifically includes the following contents: (1) An acceleration sensor is provided at the wrench handle to measure the acceleration corresponding to the wrench handle; and the tactile reaction time of the human body in response to the reaction force of the wrench is set. T .

[0018] When the screw is screwed to a position close to the end of the screwing, the reverse torque on the wrench will rise sharply, and the operator cannot accurately predict the occurrence time of the reverse torque. Therefore, when the reverse torque on the wrench rises sharply, the operator cannot react to the reverse torque, so that the reaction force causes the handle of the electric torque wrench to swing, and then the sudden swing will cause an impact on the operator's wrist or arm, and there is a risk of sprain. For this reason, in this embodiment, an acceleration sensor and a controller are set in the handle of the electric torque wrench. In this example, an accelerometer is specifically used and the accelerometer is communicated with the controller. The accelerometer is arranged in the wrench handle along the sweep direction of the wrench handle under the action of the reaction force. Therefore, the action of the wrench handle is monitored in real time by the accelerometer. When the wrench is subjected to the reverse torque, the wrench handle accelerates, so that the movement can be sensed and captured by the acceleration sensor in the handle, and the sensor value can reflect the amplitude and intensity of the handle sweep caused by the reaction force.

[0019] When the existing electric torque wrench approaches the end of the screwing action, the operator needs to apply force to resist the reverse torque of the electric torque wrench. However, since it takes a certain amount of time from the human body's tactile sense of the reverse torque to the body's reaction to apply the force to resist the reverse torque, that is, the tactile reaction time, based on this, in this embodiment, by controlling the torque output of the electric torque wrench within the tactile reaction time, the torque output of the electric torque wrench is reduced before the human body reacts and applies the resistance force, thereby reducing the reverse torque of the wrench and avoiding or reducing the discomfort caused by the reaction force. However, considering that different operators have different tactile reaction times, that is, there are differences in tactile reaction times between different individuals, in order to achieve adaptation that varies from person to person, in this embodiment, an adjustment button is provided at the handle of the electric torque wrench to adjust the action rate of the electric torque wrench to resist the reaction force to match the tactile reaction time of the operator. Among them, the default setting of the tactile reaction time T in this example is 300ms, and the tactile reaction time can be adjusted accordingly within the range of 200ms to 600ms through the adjustment button at the handle.

[0020] (2) The wrench controller obtains the signal value output by the acceleration sensor in real time m。

[0021] After the electric torque wrench is started, the acceleration sensor monitors the acceleration value of the wrench handle in real time, so as to adjust the power output of the electric torque wrench according to the acceleration change of the wrench handle. In this embodiment, the signal value m output by the acceleration sensor to the controller is an analog signal value in the range of 0 to M. The larger the value of the signal value m, the greater the acceleration of the handle movement, the greater the reverse torque borne by the wrench handle, and the electric torque wrench handle accelerates under the action of the reaction torque.

[0022] (3) Adjust the wrench motor drive current within the tactile response time T according to the current change rate that matches the signal value m output by the acceleration sensor. I .

[0023] Considering that the signal value output by the acceleration sensor is a continuous analog quantity, in order to realize that the controller controls the driving current of the driving motor according to the signal value of the acceleration sensor, in this embodiment, within the tactile reaction time T, the signal value m output by the acceleration sensor in real time is sampled with t as the sampling period, thereby dividing the movement of the handle into T / t movement intervals, and the acceleration value at the endpoint of the sampling interval is used as the control benchmark, and t Adjust the wrench motor drive current accordingly to the cycle.

[0024] After obtaining the signal value of the acceleration of each sampling point of the reverse torque during the tactile reaction time, the driving current of the wrench drive motor is adjusted according to each acceleration value. Generally speaking, when the acceleration signal value is non-zero, it means that the wrench handle is accelerating. At this time, the driving current of the wrench drive motor is correspondingly reduced, and the larger the acceleration signal value, the greater the reduction in the driving current of the drive motor. Specifically, in this embodiment, considering that the current control curve of the drive motor has a maximum current rise rate limitation, that is, the current that the drive motor can respond to cannot change suddenly, and its maximum change rate needs to be limited within the maximum current rise rate range, so the current change rate is set. k=cn ,in, c is a constant, n=k max m / m max , m max is the maximum signal value of the acceleration sensor, k max The ratio of the maximum current rise rate of the driving motor. Thus, the maximum signal value output by the acceleration sensor m max The maximum current rise rate of the driving motor k max Correspondingly, in order to achieve effective regulation of the drive motor action, ensure that the drive motor can make a corresponding response, thereby establishing the relationship between the acceleration sensor output signal value and the current change rate. Further, the wrench controller controls the wrench motor drive current in a single cycle. I=-ki+b ;in, i is the final value of the current in the previous adjustment cycle. For the initial cycle, i It is the driving current value of the wrench in the normal tightening state when the screw is not close to the end tightening position. b is a constant, k is the absolute value of the current change rate. Therefore, when the signal value output by the acceleration sensor is non-zero, the current change rate increases with the increase of the acceleration signal value, so that the current adjustment amplitude matches the movement amplitude of the wrench handle due to the reaction force, thereby reducing the output torque of the electric torque wrench, and then reducing the reaction force before the human body responds to the action, reducing or avoiding damage to the operator, and improving the comfort of use.

[0025] In some other embodiments, the wrench controller obtains the signal value output by the acceleration sensor in real time. m After that, the sampling period between adjacent sampling points is calculated tThe change rate K of the internal acceleration signal value. Considering that the movement of the wrench handle after being acted upon by the reverse torque should be a non-uniform acceleration movement, that is, the acceleration value is constantly increasing, and the change rate is a non-fixed value. Therefore, in this example, a control relationship between the change rate K of the acceleration signal value and the change rate of the driving current of the driving motor is established, and the driving current change rate reflects the driving current adjustment amplitude. The larger the change rate K of the acceleration signal value, the larger the movement amplitude of the handle per unit time, and accordingly, the driving current I of the driving motor needs to be quickly reduced, and the corresponding current change rate should also be larger; the smaller the change rate K of the acceleration signal value but greater than zero, at this time, although the handle is still accelerating, the acceleration trend per unit time is gradually decreasing, and accordingly, the driving current adjustment rate of the driving motor can be relatively slowed down. Among them, the maximum current rise rate of the driving motor corresponds to the maximum change rate K of the acceleration signal value, and the maximum change rate K of the acceleration signal value is within the range of the acceleration sensor, and is preset according to the maximum acceleration that the wrench can actually reach. The preset value, thereby ensuring that the current adjustment can be achieved to the greatest extent under the corresponding relationship when the acceleration signal changes, meets the control requirements.

[0026] See also Picture 1 Before using the electric torque wrench, the operator sets the appropriate tactile reaction time according to personal qualities. When the wrench is started, the acceleration sensor collects the acceleration value of the wrench handle and transmits it to the wrench controller. When the screw approaches the maximum screwing position, the wrench controller outputs a control signal according to the acceleration signal value, and controls the output torque of the drive motor through the motor drive circuit. In this force, the drive current of the drive motor is detected and fed back to the wrench controller so as to be used as a cycle control benchmark to obtain the final value of the current in the previous cycle.

[0027] Although some preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0028] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for controlling the reverse thrust flexibility of an electric torque wrench, characterized in that: include: (1) An acceleration sensor is provided at the wrench handle to measure the acceleration corresponding to the wrench handle; and the tactile reaction time of the human body in response to the reaction force of the wrench is set. T ; (2) The wrench controller obtains the signal value output by the acceleration sensor in real time m ; (3) Adjusting the wrench motor drive current within the tactile response time T according to the current change rate corresponding to the signal value m output by the acceleration sensor I .

2. The reverse thrust flexibility control method of an electric torque wrench according to claim 1, characterized in that: The acceleration sensor is arranged along the sweeping direction of the wrench handle under the action of the reaction force.

3. The reverse thrust flexibility control method of an electric torque wrench according to claim 1, characterized in that: The tactile reaction time T It is 200ms~600ms.

4. The reverse thrust flexibility control method of an electric torque wrench according to claim 1, characterized in that: The controller has a tactile response time T Inner t The sampling period corresponds to the signal value of the sampling acceleration sensor, and t Adjust the wrench motor drive current accordingly to the cycle.

5. The reverse thrust flexibility control method of an electric torque wrench according to claim 4, characterized in that: Calculate each sampling period separately t The signal change rate within K , the current change rate and signal change rate K Proportional relationship.

6. The reverse thrust flexibility control method of an electric torque wrench according to claim 4, characterized in that: Wrench motor driving current in period t I=-ki+b ;in, i is the final value of the current in the previous adjustment cycle, the initial cycle i is the driving current value when the wrench is normally tightened, b is a constant, k is the absolute value of the current change rate.

7. The reverse thrust flexibility control method of an electric torque wrench according to claim 6, characterized in that: Current change rate k=cn ,in, c is a constant, n=k max m / m max , m max is the maximum signal value of the acceleration sensor, k max The ratio of the maximum current rise rate of the driving motor.

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