A hand-held power tool for assembly of threaded fasteners and a control method therefor

Abstract

The application discloses a handheld electric tool for screw fastener assembly and a control method thereof, and relates to the field of electric tools.The handheld electric tool comprises a tool body, a torque detection unit, an angle detection unit and a control unit.The tool body comprises a motor and a main shaft.The torque detection unit is arranged in the tool body to detect the torque of the main shaft in real time.The angle detection unit is arranged in the tool body to detect the rotation angle of the main shaft in real time.The control unit is electrically connected with the motor, the torque detection unit and the angle detection unit.The control unit is configured to adjust the output parameter of the motor in real time according to the torque of the main shaft detected by the torque detection unit in real time.The adjustment trigger condition of the output parameter is that the real-time torque reaches a corresponding preset torque threshold.The application can reduce the load impact of the motor and the transmission mechanism, prolong the service life of the tool, improve the control accuracy of the fastener pretightening force, and meet the use requirements of high requirement assembly scenes.

Description

Technical Field

[0001] This invention relates to the field of power tools, and in particular to a handheld power tool for assembling threaded fasteners and its control method. Background Technology

[0002] Electric tightening tools typically use an electric motor as their power output, tightening fasteners to the target torque through the kinetic energy of a high-speed rotating component. These tools are widely used in assembly scenarios where strict torque accuracy is required, such as in machinery manufacturing, automotive assembly, and aerospace. Their basic structure usually includes a power unit, a reduction gear unit, a control unit, and a housing assembly. With the continuous improvement of industrial automation, the market is placing higher demands on the precision, reliability, ease of operation, and service life of tightening tools.

[0003] Currently, most electric tightening tools on the market adopt a working mode where the motor is directly connected to a reducer and then directly outputs power. These tools focus on the instantaneous output performance of the motor and the mechanical strength of the shaft. Their control logic is relatively simple, that is, to tighten the fastener from its initial state to the target torque in one go at a constant speed.

[0004] Specifically, during operation, the motor of this type of tool operates under continuous high load from startup, and the transmission mechanism (such as the reducer and output shaft) is subjected to continuous stress impact. Due to the single control method, the tool cannot adaptively adjust the motor speed and output torque according to the different tightening resistances encountered by the fastener at different stages, such as "cap seeking," "seat placement," and "seat placement completion." This easily leads to concentrated energy loss and is prone to cumulative damage to critical components such as motor windings, bearings, and transmission gears due to instantaneous overload, thus significantly shortening the overall service life of the tool. More importantly, this type of tool generally uses only a single torque threshold as the stop control signal. Under elastic tightening or soft connection conditions, fluctuations in the coefficient of friction directly result in a large dispersion of the actual preload force obtained under the same torque, which easily leads to quality problems such as insufficient tightening force or over-tightening, failing to meet the requirements of high-reliability assembly applications. Summary of the Invention

[0005] To address the technical problems of existing electric tightening tools, which suffer from shortened service life due to their simple control logic, reliance on constant speed output and a single torque threshold for shutdown, resulting in long-term concentrated loads and stress impacts on the motor and transmission mechanism, and large preload dispersion in elastic tightening or flexible connection conditions, leading to potential quality hazards such as under-tightening or over-tightening, and thus failing to meet the requirements of high-reliability assembly, this invention integrates a torque detection unit, an angle detection unit, and a control unit into the electric tightening tool. This allows for dynamic adjustment of the motor's output speed and mode based on real-time torque, and, combined with a torque and angle coordinated detection shutdown method, effectively reduces the load impact on the motor and transmission mechanism, extends the tool's service life, and improves the control accuracy of fastener preload, meeting the needs of high-requirement assembly scenarios.

[0006] In a first aspect of the invention, a handheld power tool for assembling threaded fasteners is provided, comprising:

[0007] The tool body includes a motor and a spindle;

[0008] A torque detection unit is installed inside the tool body to detect the spindle torque in real time;

[0009] An angle detection unit is installed inside the tool body to detect the rotation angle of the spindle in real time;

[0010] The control unit is electrically connected to the motor, torque detection unit and angle detection unit. The control unit is configured to adjust the output parameters of the motor in real time according to the spindle torque detected in real time by the torque detection unit. The adjustment trigger condition of the output parameters is that the real-time torque reaches the corresponding preset torque threshold.

[0011] When the real-time torque reaches the preset start-up angle detection threshold, the start-up angle detection unit simultaneously monitors the rotation angle of the spindle.

[0012] When the real-time torque reaches the preset target torque threshold and the spindle rotation angle reaches the preset target angle threshold, the control motor stops running.

[0013] With the above technical solution, firstly, the control unit can dynamically adjust the motor output parameters based on real-time torque to adapt the motor output parameters to the resistance changes of fasteners at different assembly stages, from threading and seating to final tightening. This not only optimizes energy utilization efficiency and reduces ineffective energy consumption, but also improves the stability of the operation process. Furthermore, it avoids the long-term high-load operation of the motor caused by the constant speed output of existing tools, effectively dispersing energy loss and reducing the concentrated stress impact on key components such as motor windings, bearings, and transmission gears, thus reducing cumulative component damage and extending the overall service life of the tool. Secondly, the invention employs a torque and angle coordinated detection shutdown method, which can effectively offset the influence of friction coefficient fluctuations on preload under conditions such as elastic tightening or soft connection. This significantly reduces the dispersion of preload under the same torque, avoiding quality risks such as loose assembly due to insufficient tightening force or component damage due to over-tightening, and significantly improving the reliability of fastener assembly.

[0014] In a second aspect of the invention, a control method for a handheld power tool for assembling threaded fasteners, as described above, is also provided, comprising the following steps:

[0015] Step 1: The control unit controls the motor output shaft to output at the first speed to guide the fastener into the threaded end, while the torque detection unit monitors the spindle torque in real time.

[0016] Step 2: When the spindle torque reaches the first preset torque threshold, the control unit controls the motor output shaft to output at the second speed to seat the fastener, while the torque detection unit continues to monitor the spindle torque.

[0017] Step 3: When the torque detection unit detects that the real-time torque reaches the second preset torque threshold, the control unit controls the motor to output in stages. The torque detection unit monitors the spindle torque in real time, and at the same time, the control unit controls the angle detection unit to detect the spindle rotation angle in real time.

[0018] Step 4: When the torque detection unit detects that the real-time torque reaches the preset target torque threshold, and when the angle detection unit detects that the spindle rotation angle reaches the preset target angle, the control unit controls the motor output shaft to stop rotating.

[0019] Preferred, staged outputs include:

[0020] (1) Continuous constant output stage: The control unit controls the motor to output at the third speed. When the torque detection unit detects that the real-time torque reaches the third preset torque threshold, it switches to pulse intermittent output.

[0021] (2) Pulse intermittent output stage: The control unit controls the output shaft of the motor in multiple steps in sequence. Each step has a preset target torque, and the target torque of each step gradually increases to the preset target torque threshold. At the same time, between each two adjacent steps, the control unit controls the motor output shaft to stop outputting and maintain it for a certain period of time.

[0022] With the above technical solution, the continuous constant output stage operates at the third speed, which is adapted to the resistance characteristics from the time the fastener is seated until it is tightened. This not only allows the initial tightening torque to be established slowly, but also ensures that the torque rises steadily through continuous output, providing a foundation for the subsequent pulse intermittent output. The pulse intermittent output stage uses multiple steps to output in sequence, so that the torque gradually approaches the preset target torque threshold in a step-like manner. This effectively disperses the concentrated load in the final tightening stage, reduces the risk of instantaneous motor overload, reduces stress impact on key components such as motor windings and transmission gears, and further extends the tool's service life.

[0023] The pause and maintenance time between each adjacent step provides sufficient redistribution and relaxation time for flexible fasteners such as plastics and composite materials, as well as elastic components such as elastic gaskets and sealing rings, due to the stress generated by tightening. This avoids stress concentration caused by instantaneous continuous loading, reduces the risk of deformation and cracking of fasteners caused by stress accumulation, and ensures the reliability of fastener assembly. At the same time, this step allows the drive motor to obtain a heat dissipation window during high-frequency output, reducing heat accumulation in the motor windings caused by continuous high-load operation, slowing down the aging of the motor, and dissipating the vibration energy generated by the reducer during torque transmission, reducing instantaneous impact wear in gear meshing, bearing rotation, and other parts, further extending the service life of the motor and reducer. In addition, after the stress is relaxed, the torque transmission of the fastener is more stable during subsequent tightening steps, avoiding torque overshoot or tightening deviation caused by springback, and further improving the control accuracy of the final preload.

[0024] Preferably, the first preset torque threshold, the second preset torque threshold, the third preset torque threshold, and the preset target torque threshold increase sequentially, and satisfy the following:

[0025] The first preset torque threshold is 5% to 15% of the preset target torque threshold;

[0026] The second preset torque threshold is 20% to 40% of the preset target torque threshold;

[0027] The third preset torque threshold is 45% to 65% of the preset target torque threshold.

[0028] When the above technical solution is adopted, the first preset torque threshold is set to 5% to 15% of the preset target torque threshold. This ratio range matches the low resistance characteristics of the fastener during the thread introduction stage, which avoids erroneous switching caused by too low a trigger threshold and prevents switching lag caused by too high a trigger threshold, thereby achieving smooth thread alignment and introduction.

[0029] The second preset torque threshold is set to 20% to 40% of the preset target torque threshold. This ratio range is adapted to the resistance change during the fastener seating stage. It can trigger the motor speed switch in time when the fastener is close to the seating state, avoid the impact load generated by high-speed operation during the seating process, and at the same time enable the motor to switch to a low speed state adapted to the subsequent tightening stage in advance, which helps to complete the seating process smoothly.

[0030] The third preset torque threshold is set to 45%~65% of the preset target torque threshold. This ratio range is adapted to the resistance increase stage from the initial placement to the final tightening, and triggers the switch from the continuous constant output stage to the pulse intermittent output stage. This allows the torque output mode to smoothly transition at the node where the resistance gradually increases, avoiding torque control deviation caused by improper mode switching timing. At the same time, this ratio range also reserves a reasonable range for the multi-step torque increase in the pulse intermittent output stage.

[0031] Preferably, the staged output also includes:

[0032] After the continuous constant output phase, the control unit controls the motor output shaft to stop outputting and maintain this for a certain period of time, before switching to the pulse intermittent output phase.

[0033] With the above technical solution, the stop buffer after the continuous constant output phase can dissipate the vibration energy of the spindle and transmission mechanism, and reduce residual stress and wear on components; at the same time, it can ensure that the torque stabilizes before switching to intermittent pulse output, avoid torque superposition deviation, and ensure the target torque control effect of multi-step sequence; for flexible fasteners and elastic components, it can further provide initial relaxation time for their internal initial stress, reducing the risk of deformation or cracking during subsequent pulse loading; in addition, this transition link can smoothly connect the two output modes, avoid operational fluctuations, optimize motor load distribution, reduce heat accumulation, and extend tool life.

[0034] Preferably, the first speed, the second speed, and the third speed decrease sequentially, and satisfy the following:

[0035] The first speed is 80% to 100% of the motor's rated speed;

[0036] The second speed is 50% to 70% of the motor's rated speed;

[0037] The third speed is 5% to 10% of the motor's rated speed;

[0038] The output speed of the motor output shaft during the pulse intermittent output phase shall not exceed the third speed.

[0039] When the above technical solution is adopted, the first speed is set to 80%~100% of the rated speed of the motor, which can provide sufficient power for the fastener to be introduced into the threaded end, speed up the thread alignment and introduction speed, and improve assembly efficiency.

[0040] The second speed is controlled at 50%~70% of the rated speed to adapt to the resistance changes during the fastener placement stage, avoid the impact caused by high-speed operation, ensure a smooth placement process, and reduce wear on the thread surface.

[0041] The third speed is controlled at 5%~10% of the rated speed. The low speed output meets the needs of the tightening stage after the seat is seated, which can reduce the risk of sudden torque increase.

[0042] During the intermittent pulse output phase, the motor speed is further reduced, and the torque increment rate is further slowed down, thus providing more control time for the final tightening process. During this period, the control unit can finely adjust the output parameters of each step based on the real-time feedback from the torque detection unit, correct torque deviations in a timely manner, and achieve fine control of the final tightening process. At the same time, the lower speed can reduce the load impact on the motor and transmission mechanism, and avoid damage to the tool caused by the motor starting and stopping repeatedly during the intermittent pulse output phase.

[0043] The decreasing rotational speed in each of the aforementioned steps matches the assembly process from fastener introduction, placement to tightening, and the increasing resistance pattern, ensuring that the motor output meets the assembly requirements.

[0044] Preferably, between each two adjacent steps, the control unit controls the motor output shaft to stop outputting for a period of time until the real-time torque drops back to the target torque of the previous step.

[0045] Preferably, during the pulse intermittent output phase, the target torque Ti of the i-th step is equal to the third preset torque threshold T0 and the preset target torque threshold T1. N The following relationship must be satisfied:

[0046] T i =T0+(T N -T0)×i / n, i=1,2,...,n;

[0047] Where n is the total number of steps in the pulse intermittent output phase, and i is the current step number.

[0048] By adopting the above technical solution, the torque range between the third preset torque threshold and the preset target torque threshold is linearly allocated, providing a clear and controllable torque increment standard for each step in the pulse intermittent output stage. This ensures that the target torque in each step increases linearly in a stepwise manner, avoiding control fluctuations caused by sudden torque changes. The torque increment of each step is fixed and can be flexibly adjusted by the total number of steps, n. This allows for refining the torque control granularity by increasing the number of steps, or simplifying the step settings according to assembly requirements, adapting to scenarios with different precision requirements. Simultaneously, the uniformly increasing torque can be smoothly transmitted to the fasteners, reducing instantaneous force fluctuations and lowering the risk of deformation. Combined with inter-step stop buffering, this further improves the reliability of the fastener preload.

[0049] Optionally, during the pulse intermittent output phase, the target torque T of the i-th step sequence... i With the third preset torque threshold T0 and the preset target torque threshold T N The following relationship must be satisfied:

[0050] T i =T N -(T N -T0)×e -k(i-1) , i=1,2,...,n;

[0051] Where n is the total number of steps in the pulse intermittent output phase, i is the sequence number of the current step, and k is a positive zero adjustment coefficient.

[0052] With the above technical solution, the non-linear torque increment method better matches the characteristic of the fastener resistance gradually increasing non-linearly during the actual tightening process. This creates a pattern where the torque increases rapidly in the early stages and then gradually slows down in the later stages. The initial steps can quickly narrow the gap with the preset target torque threshold, improving overall tightening efficiency. The slower torque increment rate in the later stages allows for more feedback and adjustment time for the control unit, facilitating the correction of output deviations based on real-time data from the torque detection unit and better adapting to resistance fluctuations near the final tightening stage.

[0053] The adjustment coefficient k can flexibly adjust the smoothness of torque increase. The larger the k value, the smoother the torque increase in the later stage and the higher the control precision. The smaller the k value, the more efficient the torque increase in the early stage. It can optimize the control logic according to the working conditions such as different fastener materials and assembly gaps.

[0054] Preferably, during the intermittent pulse output phase, the control unit controls the motor output shaft output in a three-step sequence, including the following steps:

[0055] When the torque detection unit detects that the real-time torque has reached the third preset torque threshold, the control unit controls the motor output shaft to output at the fourth speed. When the real-time torque reaches the first target torque, the control unit controls the motor output shaft to stop outputting. When the real-time torque drops back to the third preset torque threshold, the control unit controls the motor output shaft to output at the fourth speed.

[0056] When the real-time torque reaches the second target torque, the control unit controls the motor output shaft to stop outputting until the real-time torque reaches the first target torque again, at which point the control unit controls the motor output shaft to output at the fourth speed.

[0057] When the real-time torque reaches the third target torque, the control unit controls the motor output shaft to stop outputting until the real-time torque reaches the second target torque again. Then, the control unit controls the motor output shaft to output at the fourth speed until the real-time torque reaches the preset target torque threshold.

[0058] With the above technical solution, the first step uses the third preset torque threshold as the fallback trigger point. The machine stops after the real-time torque reaches the first target torque, and restarts output only after the torque falls back to the initial threshold. The second step uses the first target torque as the fallback reference until the second target torque is reached, at which point the machine stops. The third step uses the second target torque as the fallback trigger condition, ultimately approaching the preset target torque threshold. Through the cycle of output and shutdown in multiple steps, the influence of the fastener's elastic rebound can be offset, avoiding tightening deviations caused by excessive torque and reducing preload dispersion. This step balances tightening efficiency and control precision, enabling rapid fastener tightening while protecting the motor and reducer through multiple stop buffers, reducing the risk of fastener deformation or damage, thereby improving the stability of assembly quality.

[0059] Preferably, the preset target torque threshold is set within a preset torque range. If the angle detection unit detects that the spindle rotation angle reaches the preset target angle and the real-time torque does not exceed the highest point of the preset torque range, the control unit controls the motor output shaft to stop rotating.

[0060] If the torque detection unit detects that the real-time torque has reached the highest point of the preset torque range, and the angle detection unit detects that the spindle rotation angle has not reached the preset target angle, the control unit controls the motor output shaft to stop rotating and outputs the first alarm signal.

[0061] By adopting the above technical solution, a preset torque range replaces a single torque threshold, providing a more flexible judgment range for tightening control and adapting to torque fluctuation characteristics under different working conditions. If the spindle rotation angle reaches the preset target angle and the real-time torque does not exceed the maximum point of the range, the motor is stopped. At this time, the fastener preload is within a reasonable torque range and the rotation angle meets the standard, ensuring that the assembly effect meets the design requirements. If the real-time torque reaches the maximum point of the range but the rotation angle does not meet the standard, the motor is stopped immediately. This allows for timely inspection of foreign objects in the threaded hole, thereby avoiding deformation of the connector, thread damage, or motor overload caused by over-tightening, and preventing safety hazards caused by continuous torque increases. This ensures that the assembly process neither results in under-tightening nor over-tightening, improving the reliability of the assembly quality.

[0062] Preferably, during the pulse intermittent output phase, the control unit is further configured to calculate the rate of change of the spindle rotation angle in real time; when the real-time torque enters the preset torque range, if the rate of change of the spindle angle continues to be lower than the preset rate of change threshold and remains below the preset angle change threshold for a preset duration, the control unit controls the motor output shaft to stop rotating and outputs a second alarm signal.

[0063] When the above technical solution is adopted, if the angle change rate is consistently lower than the set threshold and remains so for a certain period of time, it indicates that the fastener has been fully tightened and there will be no further significant angle displacement. At this point, the machine can be stopped in advance without having to wait for the angle to reach the preset target value. This ensures the tightening effect, reduces unnecessary tightening time, and improves assembly efficiency. At the same time, this mechanism can adapt to the differences in elastic deformation characteristics of fasteners of different materials and specifications, avoiding over-tightening or under-tightening caused by a single angle threshold. This further reduces the preload dispersion and ensures a balance between assembly quality and efficiency.

[0064] Preferably, the control unit has a variety of tightening parameter curves that are adapted to different working conditions. The tightening parameter curves include a first preset torque threshold, a second preset torque threshold, a third preset torque threshold, the rotational speed at each stage, the number of steps in the pulse intermittent output stage, and the target torque at each step.

[0065] In the early stage of the tightening process, the control unit applies experimental torque to the fastener. By analyzing the initial response data fed back by the torque detection unit and the angle detection unit, the approximate friction coefficient and stiffness characteristics of the current fastener are evaluated. Then, the matching tightening parameter curve is automatically selected or dynamically adjusted to optimize the setting of each torque threshold, each stage speed, the number of steps in the pulse intermittent output stage, and the target torque of each step for subsequent assembly.

[0066] Automatic parameter matching reduces reliance on operator experience, eliminating the need for manual parameter adjustments based on working conditions. This lowers operational difficulty and the risk of misoperation, while improving the convenience and efficiency of the assembly process. Attached Figure Description

[0067] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0068] Figure 1 A front view of a power tool provided in an exemplary embodiment of the present invention;

[0069] Figure 2 An exploded view of the power tool provided in an exemplary embodiment of the present invention;

[0070] Figure 3 A cross-sectional view of a power tool provided in an exemplary embodiment of the present invention;

[0071] Figure 4 This is a schematic diagram of the torque detection unit and power component in an exemplary embodiment of the present invention;

[0072] Figure 5 A schematic diagram illustrating different stages of tightening fasteners with a power tool provided by the present invention;

[0073] Figure 6 This is a schematic diagram of the angle detection unit detecting the rotation angle of a fastener in this invention;

[0074] Figure 7 This is a schematic diagram of the target torque during the pulse intermittent output stage in Embodiment 1 of the present invention;

[0075] Figure 8 This is a schematic diagram of the torque-time relationship in Embodiment 3 of the present invention.

[0076] Figure Labels

[0077] 11. Outer shell assembly; 111. Front shell; 112. First handle shell; 113. Second handle shell; 114. Rear cover; 12. Power assembly; 121. Motor; 122. Reduction mechanism; 123. Spindle; 13. Control assembly; 131. Screen panel; 132. Operation buttons; 133. Reversing button; 134. Switch trigger; 135. WiFi board; 136. Scanning module; 14. Power supply; 2. Torque detection unit; 21. Connecting block; 3. Angle detection unit. Detailed Implementation

[0078] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0079] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0080] As described in the background section, in order to address the technical problems of existing electric tightening tools, which suffer from shortened service life due to their simple control logic, reliance on constant speed output and a single torque threshold for shutdown, resulting in long-term concentrated loads and stress impacts on the motor and transmission mechanism, and large preload dispersion under elastic tightening or soft connection conditions, easily leading to quality hazards such as insufficient or excessive tightening, and failing to meet the requirements of high-reliability assembly, this invention integrates a torque detection unit, an angle detection unit, and a control unit into the electric tightening tool. This allows for dynamic adjustment of the motor's output speed and output mode based on real-time torque, and, combined with a torque and angle collaborative detection shutdown method, effectively reduces the load impact on the motor and transmission mechanism, extends the tool's service life, and improves the control accuracy of fastener preload, meeting the usage requirements of high-requirement assembly scenarios.

[0081] In a first aspect of the invention, a handheld power tool for assembling threaded fasteners is provided, with reference to... Figures 1-3 The system includes a tool body, a torque detection unit 2, an angle detection unit 3, and a control unit. The tool body constitutes the main mechanical structure of the tool, ensuring the stability of the power transmission path and ease of handheld operation. The torque detection unit 2 detects the torsional force on the spindle 123 in real time and converts it into an electrical signal, providing torque feedback data to the control unit. The angle detection unit 3 monitors the number of rotations or angular displacement of the spindle 123 and quantifies it into an electrical signal, providing the control unit with deformation angle data during the fastener tightening process. The control unit receives and processes signals from the torque detection unit 2 and the angle detection unit 3, dynamically adjusting the operating state of the motor 121 according to preset logic to complete a high-precision fastener tightening process.

[0082] Specifically, in the exemplary embodiment, the tool body includes a housing assembly 11, a power assembly 12, a control assembly 13, and a power supply 14. The housing assembly 11 forms the external protective frame of the tool, providing mechanical support, handheld operation, and protection for internal components. The power assembly 12 converts electrical energy into rotational kinetic energy via a motor 121 and a transmission mechanism to drive the fasteners for tightening, thus achieving power output. The control assembly 13 executes control logic and supports human-machine interaction, enabling the operator to controllably tighten the fasteners.

[0083] Furthermore, in the exemplary embodiment, the housing assembly 11 includes a front housing 111, a first handle housing 112, a second handle housing 113, and a rear cover 114. The front housing 111, serving as the power output carrier of the tool, is made of aluminum alloy and has an internal bearing seat and shaft hole structure for fixing the output portion of the spindle 123 and the reduction mechanism 122. The first handle housing 112 and the second handle housing 113 are joined to form a cavity capable of accommodating the power assembly 12 and the control assembly 13. The surfaces of the first handle housing 112 and the second handle housing 113 are treated with an anti-slip texture. The connection between the front housing 111 and the first handle housing 112 and the second handle housing 113 is secured with screws. The rear cover 114 is located at the tail of the tool and is connected to the first handle housing 112 and the second handle housing 113 with screws.

[0084] Furthermore, in the exemplary embodiment, the power assembly 12 includes a motor 121, a reduction mechanism 122, and a main shaft 123. The motor 121 is fixed between the first handle housing 112 and the second handle housing 113. The reduction mechanism 122 is fixed inside the front housing 111. The main shaft 123 passes through a shaft hole on the front housing 111 and is rotatably connected to the front housing 111 through a bearing. The motor 121, the reduction mechanism 122, and the main shaft 123 are sequentially connected to transmit power.

[0085] Furthermore, in the exemplary embodiment, the control component 13 includes a screen panel 131, operation buttons 132, reversing buttons 133, a power switch trigger 134, a WiFi board 135, and a barcode scanning module 136.

[0086] The screen panel 131 uses an LCD display, which is embedded in a reserved window on the surface of the rear cover 114 and connected to the main board of the control unit via a flexible circuit. The screen panel 131 is used to display key parameters in real time, such as preset torque value, real-time torque reading, rotation angle, tightening result, and battery power status.

[0087] As an optional embodiment, the surface of the screen panel 131 is covered with an anti-glare and scratch-resistant hardened coating to ensure clear visibility in bright industrial environments.

[0088] As an optional embodiment, the content displayed on the screen panel 131 is dynamically driven by the control unit, supports multi-level menu navigation, and allows users to view historical tightening records or system settings.

[0089] The operation buttons 132 are located below the screen panel 131 and are physical microswitches with function icons printed on their surface. Operation buttons 132 include an OK button, a menu button, up and down selection buttons, and a return button, used in conjunction with the screen panel 131 to complete parameter settings, program selection, and function switching. The trigger signals of the buttons are directly transmitted to the control unit. Through operation buttons 132, users can quickly recall different tightening programs or adjust control parameters.

[0090] The reversing button 133 is mounted on the handle housing. It integrates a Hall element. When the user moves the button, the Hall element detects the change in magnetic field and generates a direction switching signal. This signal is transmitted to the control unit in a non-contact manner, thereby driving the motor 121 to rotate forward or in reverse.

[0091] The switch trigger 134 is located inside the handle housing and is ergonomically designed for easy triggering with the index finger.

[0092] The WiFi board 135 is integrated on the circuit board inside the handle shell. It can upload the tightening process data to the management system in real time or receive tightening programs or parameter updates remotely.

[0093] The barcode scanning module 136 is integrated into the inner bottom of the handle housing, and has a built-in image sensor and decoding chip. It can automatically identify the current assembly task by scanning the barcode on the fastener or workstation, and trigger the control unit to call the corresponding preset tightening parameters.

[0094] Furthermore, in the exemplary embodiment, the power supply 14 is snapped onto the bottom of the handle housing as a separate module. The top of the power supply 14 is provided with metal contacts that cooperate with the battery holder contacts inside the handle housing to achieve power transmission.

[0095] Specifically, in the exemplary embodiment, the torque detection unit 2 adopts a torque sensor, which is located at the transmission connection between the output shaft of the motor 121 and the reduction mechanism 122.

[0096] Furthermore, refer to Figure 4 A connecting block 21 is provided on one side of the output shaft of motor 121. The connecting block 21 has a positioning hole and a clearance hole. The clearance hole is used for the output shaft of motor 121 to pass through, and the positioning holes on both sides of the clearance hole are used to interlock and fix the connecting block 21 to the housing of motor 121 with screws. The torque sensor body is formed into a ring structure, with a detection hole in the middle. The detection hole is sleeved on the output shaft of motor 121 to realize the detection of its torque, and then the output torque of main shaft 123 is obtained through the transmission ratio of reduction mechanism 122.

[0097] Furthermore, a hexagonal boss is provided in the middle of the side of the torque sensor near the motor 121, and the clearance hole of the aforementioned connecting block 21 is formed as an internal hexagonal hole. The two cooperate to fix the position of the torque sensor. Even further, multiple recesses are provided on the sidewall of the torque sensor, and multiple protrusions are formed on the housing of the reduction mechanism 122 to cooperate with the recesses. The two cooperate to further fix the position of the torque sensor.

[0098] Specifically, in the exemplary embodiment, the angle detection unit 3 adopts a photoelectric encoder, which is fixed to the tail end of the motor 121 to identify changes in the magnetic field and grating signals, and converts the mechanical rotation motion of the output shaft of the motor 121 into a pulse signal. The frequency of the pulse signal is proportional to the rotation angle of the output shaft of the motor 121. By counting the number of pulses and the transmission ratio of the reduction mechanism 122, the rotation angle value of the main shaft 123 can be obtained.

[0099] Specifically, in the exemplary embodiment, the control unit is electrically connected to the aforementioned motor 121, torque detection unit 2 and angle detection unit 3. The control unit is configured to adjust the output parameters of the motor 121 in real time according to the spindle torque detected in real time by the torque detection unit 2. The adjustment trigger condition for the output parameters is that the real-time torque reaches the corresponding preset torque threshold.

[0100] When the real-time torque reaches the preset starting angle detection threshold, the starting angle detection unit 3 simultaneously monitors the rotation angle of the spindle 123.

[0101] When the real-time torque reaches the preset target torque threshold and the spindle rotation angle reaches the preset target angle threshold, the control motor 121 stops running.

[0102] Furthermore, the control unit has a variety of tightening parameter curves pre-stored to adapt to different working conditions. The tightening parameter curves include a first preset torque threshold, a second preset torque threshold, a third preset torque threshold, the speed of each stage, the number of steps in the pulse intermittent output stage, and the target torque of each step.

[0103] In the early stages of the tightening process, the control unit applies an experimental torque to the fastener. By analyzing the initial response data fed back by the torque detection unit 2 and the angle detection unit 3, the approximate friction coefficient and stiffness characteristics of the current fastener are evaluated. This allows for the automatic selection or dynamic adjustment of a matching tightening parameter curve, optimizing the torque thresholds, rotational speeds, number of steps in the pulse intermittent output stage, and target torque settings for subsequent assembly. This reduces reliance on operator experience and lowers the operational difficulty and risk of misoperation.

[0104] The control unit can dynamically adjust the output parameters of the motor 121 based on real-time torque, so that the output parameters of the motor 121 can adapt to the resistance changes of the fastener at different assembly stages, from threading and seating to final tightening. This not only optimizes energy utilization efficiency and reduces ineffective energy consumption and improves the smoothness of the operation process, but also avoids the long-term high-load operation of the motor 121 caused by the constant speed output of existing tools. It effectively disperses energy loss, reduces the concentrated stress impact on key components such as the motor 121 windings, bearings and transmission gears, reduces cumulative damage to components, and extends the overall service life of the tool. Secondly, the present invention adopts a torque and angle coordinated detection shutdown method, which can effectively offset the influence of friction coefficient fluctuations on preload under working conditions such as elastic tightening or soft connection. It can significantly reduce the dispersion of preload under the same torque, avoid quality hazards such as loose assembly caused by insufficient tightening force or component damage caused by over-tightening, and significantly improve the reliability of fastener assembly.

[0105] In a second aspect of the invention, a control method for a handheld power tool for assembling threaded fasteners, as described above, is also provided, referring to... Figure 5 and Figure 6 It includes the following steps:

[0106] Step 1: The control unit controls the output shaft of motor 121 to output at the first speed (80%~100% of the rated speed of motor 121), corresponding to the idle and cap-finding stage, so as to introduce the fastener into the thread. At the same time, the torque detection unit 2 monitors the spindle torque in real time.

[0107] Step 2: When the spindle torque reaches the first preset torque threshold (5%~15% of the preset target torque threshold), the control unit controls the output shaft of motor 121 to output at the second speed (50%~70% of the rated speed of motor 121), corresponding to the pre-seat stage, to seat the fastener. At the same time, the torque detection unit 2 continues to monitor the spindle torque.

[0108] Step 3: When the torque detection unit 2 detects that the real-time torque reaches the second preset torque threshold (20%~40% of the preset target torque threshold), the control unit controls the motor 121 to output in stages. The torque detection unit 2 monitors the spindle torque in real time, and at the same time, the control unit controls the angle detection unit 3 to detect the spindle rotation angle in real time; corresponding to the seating stage, to continue tightening the fasteners that have been seated. The staged output includes:

[0109] (1) Continuous constant output stage: The control unit controls the motor 121 to output at the third speed (5%~10% of the rated speed of the motor 121);

[0110] (2) When the torque detection unit 2 detects that the real-time torque reaches the third preset torque threshold (45%~65% of the preset target torque threshold), the control unit controls the output shaft of motor 121 to stop outputting and maintain it for a certain period of time, switching to pulse intermittent output;

[0111] (3) Pulse intermittent output stage: The control unit controls the output shaft of motor 121 to output in multiple steps. Each step has a preset target torque, and the target torque of each step gradually increases to the preset target torque threshold. At the same time, between each two adjacent steps, the control unit controls the output shaft of motor 121 to stop outputting and maintain it for a certain period of time; wherein, in the pulse intermittent output stage, the target torque T of the i-th step is i With the third preset torque threshold T0 and the preset target torque threshold T N The following relationship must be satisfied:

[0112] T i =T0+(T N -T0)×i / n, i=1,2,...,n;

[0113] Where n is the total number of steps in the pulse intermittent output phase, and i is the current step number.

[0114] Step 4: When the torque detection unit 2 detects that the real-time torque has reached the preset target torque threshold;

[0115] If the angle detection unit 3 detects that the spindle rotation angle has reached the preset target angle and the real-time torque has not exceeded the highest point of the preset torque range, the control unit controls the output shaft of the motor 121 to stop rotating.

[0116] If the torque detection unit 2 detects that the real-time torque reaches the highest point of the preset torque range, and the angle detection unit 3 detects that the spindle rotation angle has not reached the preset target angle, the control unit controls the output shaft of the motor 121 to stop rotating and outputs the first alarm signal through the screen panel 131.

[0117] During the intermittent pulse output phase, the control unit calculates the rate of change of the spindle rotation angle in real time. When the real-time torque enters the preset torque range, if the rate of change of the spindle angle 123 continues to be lower than the preset rate of change threshold and remains below the preset time, the control unit controls the output shaft of the motor 121 to stop rotating and outputs a second alarm signal through the screen panel 131.

[0118] Example 1

[0119] A control method for a handheld power tool includes the following steps:

[0120] Step 1: The control unit controls the output shaft of motor 121 to output at the first speed to guide the fastener into the threaded opening, while the torque detection unit 2 monitors the spindle torque in real time.

[0121] In this step, the first rotational speed is set to a specific value of 18,000 rpm (based on 90% of the rated speed of motor 121, which is 20,000 rpm), aiming to quickly align and screw ordinary screws into the threaded opening through high-speed rotation, thereby optimizing assembly efficiency. Torque detection unit 2 is activated simultaneously to monitor the spindle torque value in real time.

[0122] Step 2: When the spindle torque reaches the first preset torque threshold, the control unit controls the output shaft of motor 121 to output at the second speed to seat the fastener. At the same time, the torque detection unit 2 continues to monitor the spindle torque.

[0123] The first preset torque threshold is set to a specific value of 1.2 Nm (based on 10% of the preset target torque threshold of 12 Nm), corresponding to the state where a normal screw begins to contact the workpiece and is about to be seated. The control unit immediately switches the motor speed to the second speed, namely 12,000 rpm (based on 60% of the rated speed), to reduce motion inertia, allow the screw to be seated smoothly, and reduce impact wear on the thread surface.

[0124] Step 3: When the torque detection unit 2 detects that the real-time torque reaches the second preset torque threshold, the control unit controls the motor 121 to output in stages. The torque detection unit 2 monitors the spindle torque in real time. At the same time, the control unit controls the angle detection unit 3 to detect the spindle rotation angle in real time.

[0125] The second preset torque threshold is set to a specific value of 3.6 Nm (based on 30% of the target torque threshold), corresponding to the state where the fastener has been seated but not yet tightened. The staged output includes the following sub-steps:

[0126] (1) Continuous constant output stage: The control unit controls the motor 121 to output at the third speed, which is 1500 rpm (7.5% of the rated speed), in order to smoothly establish torque at a low speed and reduce sudden load. At the same time, the angle detection unit 3 is activated in this stage to monitor the spindle rotation angle in real time to reduce the impact of friction coefficient fluctuations.

[0127] (2) When the torque detection unit 2 detects that the real-time torque reaches the third preset torque threshold (i.e., the seating torque), the control unit controls the output shaft of motor 121 to stop outputting and maintain it for 50 milliseconds, switching to pulse intermittent output; the third preset torque threshold is set to a specific value of 6 Nm (based on 50% of the target torque threshold) to avoid control deviations caused by being too early or too late. The brief stop allows stress relaxation and heat dissipation, improving component durability.

[0128] (3) Pulse intermittent output stage: Refer to Figure 7The control unit controls the output shaft of motor 121 in three steps. Each step has a preset target torque, namely 8 Nm for the first step, 10 Nm for the second step, and 12 Nm for the third step. The torque gradually increases between each step. At the same time, between each two adjacent steps, the control unit controls the output shaft of motor 121 to stop outputting and maintain it for 100 milliseconds to allow stress redistribution.

[0129] Step 4: When the torque detection unit 2 detects that the real-time torque reaches the preset target torque threshold, and when the angle detection unit 3 detects that the spindle rotation angle reaches the preset target angle, the control unit controls the output shaft of motor 121 to stop rotating.

[0130] In this final step, the preset target torque threshold is set to a specific value of 12 Nm, and the preset target angle is set to 100° (for the typical preload requirement of ordinary screws). The control unit continuously compares real-time data: if the torque reaches 12 Nm and the angle reaches 100°, motor 121 immediately stops, indicating that the tightening is qualified; if the torque reaches the safety upper limit (15 Nm) first but the angle does not meet the standard, the machine is forcibly stopped and the first alarm signal is output to prevent over-tightening damage. In addition, during the pulse intermittent output phase, the control unit calculates the rate of change of the spindle rotation angle in real time; when the real-time torque enters the preset torque range (9 Nm-15 Nm), if the rate of change of the angle remains below the preset threshold (0.5° / s) for 1 second, the machine is stopped in advance and a second alarm signal is output. This ensures assembly quality and avoids preload dispersion problems.

[0131] Example 2

[0132] A control method for a handheld power tool is provided, applicable to flexible working conditions, i.e., scenarios where fasteners have elastic washers underneath. Therefore, this embodiment, based on Embodiment 1, adjusts the control parameters and logic to achieve finer torque increments and longer stress relaxation times, avoiding overtightening, washer crushing, or insufficient preload. The control method specifically includes the following steps:

[0133] Step 1: The control unit controls the output shaft of motor 121 to output at the first speed to guide the fastener into the threaded opening, while the torque detection unit 2 monitors the spindle torque in real time.

[0134] In this step, the first rotational speed is set to a specific value of 16,000 rpm (based on 80% of the rated speed of motor 121, which is 20,000 rpm), slightly lower than in Embodiment 1, so as to introduce the fastener into the threaded opening at a lower rotational speed. The torque detection unit 2 is started synchronously to monitor the spindle torque value in real time.

[0135] Step 2: When the spindle torque reaches the first preset torque threshold, the control unit controls the output shaft of motor 121 to output at the second speed to seat the fastener. At the same time, the torque detection unit 2 continues to monitor the spindle torque.

[0136] The first preset torque threshold is set to a specific value of 1.5 Nm (12.5% ​​of the preset target torque threshold of 12 Nm, slightly higher than in Example 1), corresponding to the state where the fastener has entered the threaded end. The control unit immediately switches the motor speed to the second speed, namely 10,000 rpm (based on 50% of the rated speed). The torque detection unit 2 continues to track the torque increase trend.

[0137] Step 3: When the torque detection unit 2 detects that the real-time torque reaches the second preset torque threshold, the control unit controls the motor 121 to output in stages. The torque detection unit 2 monitors the spindle torque in real time. At the same time, the control unit controls the angle detection unit 3 to detect the spindle rotation angle in real time.

[0138] The second preset torque threshold is set to a specific value of 4 Nm (based on 33.3% of the target torque threshold, higher than in Example 1), marking the state where the fastener has just finished settling and the washer is about to be compressed, thus entering the fine control stage of the tightening process. The staged output includes the following sub-steps:

[0139] (1) Continuous constant output stage: The control unit controls the motor 121 to output at a third speed of 800 rpm (4% of the rated speed, significantly lower than in Example 1), which aims to smoothly establish torque at an extremely low speed to adapt to the slow compression characteristics of the gasket and reduce the impact of sudden torque changes on the gasket. At the same time, the angle detection unit 3 is activated during this stage, and the control unit calculates the angle change rate in real time.

[0140] (2) When the torque detection unit 2 detects that the real-time torque reaches the third preset torque threshold, the control unit controls the output shaft of the motor 121 to stop outputting and maintain it for 100 milliseconds (longer than the 50 milliseconds in Example 1), switching to pulse intermittent output; the third preset torque threshold is set to a specific value of 6 Nm (based on 50% of the target torque threshold) to avoid premature switching that could lead to unstable control. The extended stop time allows the gasket stress to fully relax, preventing cumulative deformation.

[0141] (3) Pulse Intermittent Output Stage: The control unit controls the output shaft of motor 121 in four steps (more than the three in Example 1). Each step has a preset target torque, namely, the target torque of the first step is 6.5 Nm, the second step is 8 Nm, the third step is 9.5 Nm, and the fourth step is 12 Nm. The torque increment between each step is smaller to ensure that the torque increases slowly. At the same time, between each two adjacent steps, the control unit controls the output shaft of motor 121 to stop outputting and maintain it for 150 milliseconds (longer than the 100 milliseconds in Example 1) to achieve sufficient redistribution of gasket stress.

[0142] Step 4: When the torque detection unit 2 detects that the real-time torque reaches the preset target torque threshold, and when the angle detection unit 3 detects that the spindle rotation angle reaches the preset target angle, the control unit controls the output shaft of motor 121 to stop rotating.

[0143] In this final step, the preset target torque threshold is set to a specific value of 12 Nm, but the preset target angle is set to 120° (higher than 100° in Example 1, to compensate for the additional elongation required due to washer compression). The control unit continuously compares real-time data: if the angle reaches 120° and the torque is within the preset torque range (11 Nm to 13 Nm), the motor 121 immediately stops, indicating that the tightening is qualified; if the torque reaches the safety upper limit (14 Nm) first but the angle does not meet the standard, the machine is forcibly stopped and a first alarm signal is output to prevent washer overpressure, fastener damage, or other product quality problems. In addition, during the pulse intermittent output phase, the control unit relies more on the angle change rate; when the real-time torque enters the preset range, if the angle change rate is continuously lower than the preset threshold (0.3° / s, lower than 0.5° / s in Example 1) and maintained for 2 seconds (longer than 1 second in Example 1), the machine is stopped early and a first alarm signal is output to avoid over-compression of the washer. This ensures that the preload force can still be accurately controlled under elastic conditions.

[0144] Example 3

[0145] In this embodiment, a control method for a handheld power tool is provided for high-precision working conditions, such as the assembly of fasteners in soft materials or scenarios with variable coefficients of friction. Based on Embodiment 2, this embodiment adjusts the control strategy during the intermittent pulse output phase to better adapt to nonlinear resistance changes, thereby improving the smoothness of the tightening process and the consistency of preload. (Refer to...) Figure 8 The control method includes the following steps:

[0146] Step 1: The control unit controls the output shaft of motor 121 to output at the first speed to guide the fastener into the threaded opening, while the torque detection unit 2 monitors the spindle torque in real time.

[0147] In this step, the initial rotational speed is set to a specific value of 17,000 rpm (based on 85% of the rated speed of motor 121, which is 20,000 rpm). This is intended to smoothly introduce the fastener into the threaded end at a moderate speed, reducing initial impact and making it suitable for soft materials or high-friction conditions. Torque detection unit 2 starts synchronously to monitor the spindle torque value in real time.

[0148] Step 2: When the spindle torque reaches the first preset torque threshold, the control unit controls the output shaft of motor 121 to output at the second speed to seat the fastener. At the same time, the torque detection unit 2 continues to monitor the spindle torque.

[0149] The first preset torque threshold is set to a specific value of 1.5 Nm, corresponding to the state when the fastener has just entered the thread. The control unit immediately switches the motor speed to the second speed, namely 11,000 rpm (based on 55% of the rated speed), to reduce motion inertia and make the seating process smoother. The torque detection unit 2 continues to track the torque increase trend; under nonlinear operating conditions, torque growth may be uneven, so a moderate reduction in speed helps to more accurately monitor state changes and provides a buffer for subsequent fine control.

[0150] Step 3: When the torque detection unit 2 detects that the real-time torque reaches the second preset torque threshold, the control unit controls the motor 121 to output in stages. The torque detection unit 2 monitors the spindle torque in real time. At the same time, the control unit controls the angle detection unit 3 to detect the spindle rotation angle in real time.

[0151] The second preset torque threshold is set to a specific value of 3 Nm, corresponding to the state where the fastener has been seated but not yet tightened. The staged output includes the following sub-steps:

[0152] (1) Continuous constant output stage: The control unit controls the motor 121 to output at a third speed of 1000 rpm (based on 5% of the rated speed, lower than in Example 2), which aims to smoothly establish torque at a low speed and reduce fluctuations caused by nonlinear resistance. The angle detection unit 3 is activated in this stage to monitor the spindle rotation angle in real time; the control unit calculates the angle change rate synchronously.

[0153] (2) When the torque detection unit 2 detects that the real-time torque reaches the third preset torque threshold, the control unit controls the output shaft of the motor 121 to stop outputting and maintain it for 80 milliseconds, switching to pulse intermittent output; the third preset torque threshold is set to a specific value of 5 Nm to ensure that the mode switching is carried out in the middle of the resistance rise.

[0154] (3) Pulse intermittent output stage: The control unit controls the output shaft of motor 121 in six steps (n=6) sequentially. The target torque Ti of each step is calculated through a nonlinear relationship:

[0155] T i =TN -(T N -T0)×e -k(i-1) , i=1,2,...,n;

[0156] The first step target torque T1 = 6 Nm (e^0 = 1 when i = 1), the second step T2 ≈ 12 - 6 × e^{-0.5} ≈ 8.36 Nm, the third step T3 ≈ 12 - 6 × e^{-1} ≈ 9.79 Nm, the fourth step T4 ≈ 10.92 Nm, the fifth step T5 ≈ 11.45 Nm, and the sixth step T6 ≈ 11.78 Nm.

[0157] That is, the torque gradually increases in a non-linear manner from the third preset torque threshold T0 to the preset target torque threshold T. N The initial increment is large, and the increment decreases in the later stage to adapt to nonlinear resistance changes.

[0158] Meanwhile, between each two adjacent steps, the control unit controls the output shaft of motor 121 to stop outputting for a period of time until the real-time torque drops back to the target torque of the previous step, so as to achieve sufficient stress relaxation.

[0159] Step 4: When the torque detection unit 2 detects that the real-time torque reaches the preset target torque threshold, and when the angle detection unit 3 detects that the spindle rotation angle reaches the preset target angle, the control unit controls the output shaft of motor 121 to stop rotating.

[0160] In this final step, the preset target torque threshold is set to a specific value of 12 Nm, and the preset target angle is set to 110°. The control unit continuously compares real-time data: if the torque reaches 12 Nm and the angle reaches 110°, the motor 121 immediately stops, indicating that the tightening is qualified; if the torque reaches the safety upper limit (13.5 Nm) first but the angle does not meet the standard, the machine is forcibly stopped and the first alarm signal is output. In addition, during the pulse intermittent output phase, the control unit relies more on the angle change rate; when the real-time torque enters the preset range (e.g., 11 Nm to 13 Nm), if the angle change rate is continuously lower than the preset threshold (0.4° / s) and remains below it for 1.5 seconds, the machine is stopped early and the second alarm signal is output. This exponentially increasing relationship reduces torque abrupt changes and improves the consistency of preload by adapting to nonlinear resistance; the total number of steps is increased to six, making the control more precise and suitable for soft materials or scenarios with large fluctuations in the coefficient of friction.

[0161] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0162] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A handheld power tool for assembling threaded fasteners, characterized in that, include: The tool body includes a motor and a spindle; A torque detection unit is installed inside the tool body to detect the torque of the spindle in real time; An angle detection unit is installed inside the tool body to detect the rotation angle of the spindle in real time; A control unit, electrically connected to the motor, the torque detection unit, and the angle detection unit, is configured to adjust the motor's output parameters in real time based on the spindle torque detected by the torque detection unit. The adjustment of the output parameters is triggered when the real-time torque reaches a corresponding preset torque threshold. When the real-time torque reaches a second preset torque threshold, the control unit controls the motor to output in stages, including: Continuous constant output stage: The control unit controls the motor to output at the third speed. When the torque detection unit detects that the real-time torque reaches the third preset torque threshold, it switches to pulse intermittent output. Pulse intermittent output stage: The control unit controls the output shaft of the motor in multiple steps in sequence. Each step has a preset target torque, and the target torque of each step gradually increases to the preset target torque threshold. When the real-time torque reaches the preset start-up angle detection threshold, the angle detection unit is activated and the rotation angle of the spindle is monitored synchronously. When the real-time torque reaches the preset target torque threshold and the spindle rotation angle reaches the preset target angle threshold, the motor is controlled to stop running.

2. A control method for a handheld power tool for assembling threaded fasteners according to claim 1, characterized in that, Includes the following steps: Step 1: The control unit controls the motor output shaft to output at the first speed to guide the fastener into the threaded end, while the torque detection unit monitors the spindle torque in real time. Step 2: When the spindle torque reaches the first preset torque threshold, the control unit controls the motor output shaft to output at the second speed to seat the fastener, while the torque detection unit continues to monitor the spindle torque. Step 3: When the torque detection unit detects that the real-time torque reaches the second preset torque threshold, the control unit controls the motor to output in stages. The torque detection unit monitors the spindle torque in real time, and at the same time, the control unit controls the angle detection unit to detect the spindle rotation angle in real time. The phased output includes: Continuous constant output stage: The control unit controls the motor to output at the third speed. When the torque detection unit detects that the real-time torque reaches the third preset torque threshold, it switches to pulse intermittent output. Pulse intermittent output stage: The control unit controls the output shaft of the motor in multiple steps in sequence. Each step has a preset target torque, and the target torque of each step gradually increases to the preset target torque threshold. Step 4: When the torque detection unit detects that the real-time torque reaches the preset target torque threshold, and when the angle detection unit detects that the spindle rotation angle reaches the preset target angle, the control unit controls the motor output shaft to stop rotating.

3. The control method according to claim 2, characterized in that, During the intermittent pulse output phase, between each two adjacent steps, the control unit controls the motor output shaft to stop outputting and maintain this for a certain period of time.

4. The control method according to claim 3, characterized in that, The first preset torque threshold, the second preset torque threshold, the third preset torque threshold, and the preset target torque threshold increase sequentially, and satisfy the following: The first preset torque threshold is 5% to 15% of the preset target torque threshold; The second preset torque threshold is 20% to 40% of the preset target torque threshold; The third preset torque threshold is 45% to 65% of the preset target torque threshold.

5. The control method according to claim 3, characterized in that, The phased output also includes: After the continuous constant output phase, the control unit controls the motor output shaft to stop outputting and maintain this for a certain period of time, and then switches to the pulse intermittent output phase.

6. The control method according to claim 3, characterized in that, The first rotational speed, the second rotational speed, and the third rotational speed decrease sequentially, and satisfy the following: The first speed is 80% to 100% of the motor's rated speed; The second speed is 50% to 70% of the motor's rated speed; The third speed is 5% to 10% of the motor's rated speed; The output speed of the motor output shaft during the pulse intermittent output phase is not higher than the third speed.

7. The control method according to claim 3, characterized in that, Between each two adjacent steps, the control unit controls the motor output shaft to stop outputting for a period of time until the real-time torque drops back to the target torque of the previous step.

8. The control method according to claim 3, characterized in that, During the intermittent pulse output phase, the target torque T of the i-th step sequence i With the third preset torque threshold T0 and the preset target torque threshold T N The following relationship must be satisfied: T i =T0+(T N -T0)×i / n,i=1,2,...,n; Where n is the total number of steps in the pulse intermittent output phase, and i is the current step number.

9. The control method according to claim 4, characterized in that, During the intermittent pulse output phase, the control unit controls the motor output shaft output in a three-step sequence, including the following steps: When the torque detection unit detects that the real-time torque has reached the third preset torque threshold, the control unit controls the motor output shaft to output at the fourth speed. When the real-time torque reaches the first target torque, the control unit controls the motor output shaft to stop outputting. When the real-time torque drops back to the third preset torque threshold, the control unit controls the motor output shaft to output at the fourth speed. When the real-time torque reaches the second target torque, the control unit controls the motor output shaft to stop outputting until the real-time torque reaches the first target torque again, at which point the control unit controls the motor output shaft to output at the fourth speed. When the real-time torque reaches the third target torque, the control unit controls the motor output shaft to stop outputting until the real-time torque reaches the second target torque again. Then, the control unit controls the motor output shaft to output at the fourth speed until the real-time torque reaches the preset target torque threshold.

10. The control method according to claim 3, characterized in that, The preset target torque threshold is set within a preset torque range. If the angle detection unit detects that the spindle rotation angle reaches the preset target angle and the real-time torque does not exceed the highest point of the preset torque range, the control unit controls the motor output shaft to stop rotating. If the torque detection unit detects that the real-time torque reaches the highest point of the preset torque range, and the angle detection unit detects that the spindle rotation angle has not reached the preset target angle, then the control unit controls the motor output shaft to stop rotating.

Images