PCB synchronous tightening device and control method thereof

Abstract

The application discloses a PCB synchronous tightening device, which comprises a shell (1), a driving shaft body (2) connected with a rotating motor is arranged in the center of the shell (1), a driving gear (3) is arranged on the driving shaft body (2) and located in the shell (1), a driven gear (4) is arranged in the shell (1) through a rotating shaft and engaged with the driving gear (3), an electromagnetic clutch (5) is arranged at the lower part of the driven gear (4), and a sleeve (6) with a built-in torque detector is arranged at the lower part of the electromagnetic clutch (5). The application realizes the simultaneous tightening of screws, so that the PCB can be subjected to the tightening force simultaneously, and the board body can keep good levelness.

Description

TECHNICAL FIELD

[0001] The application relates to the field of PCB mounting equipment, in particular to a PCB synchronous tightening device and a control method thereof. BACKGROUND

[0002] When the controller of a power steering system is installed with a PCB, two circuit boards are arranged in a stacked manner, and the lower circuit board needs to be screwed first, and then the upper circuit board is installed. For example, a Chinese invention patent with the publication number CN112171255B discloses an automobile power steering assembly equipment, wherein a screw installation device is arranged on the other side of the PCB plate conveying device away from the PCB plate dispensing device, and comprises a screw installation device frame and a screw installation device workbench fixedly arranged at the upper end of the screw installation device frame. The screw installation mechanism is a single installation arm, and the screw needs to be tightened one by one when the PCB is installed. After one end of the screw is tightened, the PCB will be raised at the other end due to the tightening force of the screw, and the levelness of the PCB will be reduced. SUMMARY

[0003] The application aims to provide a PCB synchronous tightening device and a control method thereof. The application realizes simultaneous screw tightening, so that the PCB can simultaneously receive the tightening force and maintain good levelness.

[0004] The technical scheme of the application is a PCB synchronous tightening device, which comprises a shell, a driving shaft body connected with a rotary motor is arranged at the center of the shell, a driving gear is arranged on the driving shaft body and located in the shell, a driven gear is arranged in the shell through a rotating shaft and engaged with the driving gear, an electromagnetic clutch is arranged at the lower part of the driven gear, and a sleeve with a built-in torque detector is arranged at the lower part of the electromagnetic clutch.

[0005] The control method of the above-mentioned PCB synchronous tightening device is implemented, and the specific steps are as follows:

[0006] S1: based on machine vision detection, the thread of the screw is detected, if there is a defect, the thread is replaced, if the thread of the screw is normal, the driving gear drives the driven gear to rotate, the electromagnetic clutch is started, the sleeve generates magnetic attraction force, the sleeve finds the cap end of the screw and is clamped into the sleeve, a plurality of sleeves are moved to the corresponding screw holes, the driving shaft body rotates to drive the driving gear to rotate, the driven gear engaged with the driving gear rotates, a plurality of sleeves rotate simultaneously, and the simultaneous fitting and tightening of a plurality of screws are realized, that is, the screw cap is fitted with the PCB;

[0007] S2: judging whether the head of the screw and the PCB board reach the fitting point through machine vision detection, if not, rotating the sleeve reversely to rotate out the screw, and repeating the tightening action, if yes, finally tightening the screw;

[0008] S3: detecting the finally tightened screw to judge whether the tightened screw meets the installation standard.

[0009] In the foregoing PCB board synchronous tightening control method, in step 1, the sleeve is rotated at a low speed, so that the screw cap end can be stably entered into the sleeve, and the sleeve is prevented from idling without the screw during screw installation.

[0010] In the foregoing PCB board synchronous tightening control method, in step 1, the sleeve is rotated at a high speed during screw fitting and tightening, so that the tightening time is reduced, and the installation efficiency is improved.

[0011] In the foregoing PCB board synchronous tightening control method, in step 2, the sleeve is rotated at a low speed during final screw tightening, so that the screw is better tightened, and the tightening precision is improved.

[0012] In the foregoing PCB board synchronous tightening control method, in step 1, the magnetic attraction force of the sleeve is changed by changing the current size in the electromagnetic clutch during screw fitting and tightening, and then the torque during screw tightening is controlled.

[0013] In the foregoing PCB board synchronous tightening control method, the screw is fitted and tightened in a diagonal screwing mode, so that the horizontal degree of the PCB board is maintained.

[0014] In the foregoing PCB board synchronous tightening control method, when the screws are tightened in a diagonal mode, the electromagnetic clutch is divided into two groups in a diagonal mode, the current is first input into the first group of electromagnetic clutches, the first group of electromagnetic clutches drives the corresponding sleeve to rotate, and the first group of screws is tightened, when the first group of screws is tightened to the expected torque, the second group of electromagnetic clutches is powered, the second group of screws starts to be tightened and reaches the expected torque, the current in the first group of electromagnetic clutches is increased, so that the first group of screws is tightened to the rated torque, then the second group of electromagnetic clutches is increased, the second screw is tightened to the rated torque, and the tightening torque is detected by the torque detector.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. In this invention, the electromagnetic clutch is activated, the sleeve has magnetic attraction, the power component drives the drive shaft to rotate, the drive gear on the drive shaft rotates, the drive gear drives the driven gears around it to rotate, the sleeve under the driven gears rotates, the nut end of the screw enters the sleeve, the screw aligns with the screw hole, multiple screws rotate simultaneously, the screws are tightened, and the PCB board is installed and fixed; by rotating multiple sleeves at the same time, the screws are tightened simultaneously, so that the PCB board can be subjected to tightening force at the same time, and the board body maintains a good levelness.

[0017] 2. When finally tightening the screw, the sleeve rotates slowly to tighten the screw better and improve the tightening accuracy.

[0018] 3. The sleeve rotates at a low speed, which allows the nut end of the screw to enter the sleeve stably, preventing the sleeve from spinning freely when the screw is installed if there is no screw inside.

[0019] 4. By changing the current in the electromagnetic clutch, the magnetic attraction force of the sleeve can be changed, thereby controlling the torque when tightening the screw, improving the flexibility of screw tightening, and meeting different installation requirements. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the drive gear;

[0022] Figure 3 This is a control flowchart of the present invention;

[0023] Figure 4 This is the control circuit diagram for PWM.

[0024] The markings in the attached diagram are as follows: 1-housing, 2-drive shaft, 3-drive gear, 4-driven gear, 5-electromagnetic clutch, 6-sleeve. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0026] Example: A PCB board synchronous tightening device, including a housing 1, as shown in the attached figure. Figure 1 and 2 As shown, the housing 1 has a drive shaft 2 connected to a rotary motor at its center. A drive gear 3 is provided on the drive shaft 2 and inside the housing 1. A driven gear 4 is provided inside the housing 1 via a rotating shaft and meshes with the drive gear 3. An electromagnetic clutch 5 is provided at the lower part of the driven gear 4. A sleeve 6 with a built-in torque detector is provided at the lower part of the electromagnetic clutch 5. The electromagnetic clutch mainly controls whether the sleeve rotates coaxially with the driven gear.

[0027] The control method for implementing the synchronous tightening device of the PCB board is as follows:

[0028] S1: As attached Figure 3 As shown, the control process for synchronous screw tightening is based on machine vision inspection. The screw threads are inspected, and if defects are found, the threads are replaced. If the screw threads are normal, the drive gear drives the driven gear to rotate, the electromagnetic clutch is activated, and the sleeve generates magnetic attraction. The sleeve finds the screw cap and the screw is inserted into the sleeve. The sleeve rotates at a low speed to ensure that the screw cap can be stably inserted into the sleeve, preventing the sleeve from being empty. During screw installation, the sleeves rotate freely. Multiple sleeves move to the corresponding screw holes, the drive shaft rotates, driving the drive gear to rotate. The driven gear meshing with the drive gear rotates, and multiple sleeves rotate simultaneously, achieving simultaneous contact and tightening of multiple screws, that is, the screw cap is in contact with the PCB board. The rotation speed of the sleeve is relatively fast when the screw is contacted and tightened, reducing tightening time and improving installation efficiency.

[0029] S2: Through machine vision inspection, determine whether the screw head has reached the contact point with the PCB board. If the contact point has not been reached, the screw is unscrewed by rotating the sleeve in the opposite direction and the tightening action is repeated. If the contact point has been reached, the screw is finally tightened. When the screw is finally tightened, the sleeve rotates slowly to tighten the screw better and improve the tightening accuracy. The purpose of the final tightening is to re-tighten the screw that has been contacted and tightened, and improve the stability.

[0030] S3: detecting the final tightened screw, judging whether the tightened screw meets the installation standard; in the final tightening stage of the screw, it will go through three stages: elastic stage, plate elastic stage and plastic stage. Elastic region: torque and angle are proportional, torque rises with the increase of angle, the length of the screw will not change after loosening; semi-elastic region: also called super-elastic region, limited by yield point, the slope of torque rising with angle gradually becomes smaller; plastic region: the screw is permanently lengthened, if the screw is tightened continuously, it will fail or even break. By synchronously controlling the tightening of the screw, it is ensured that multiple screws can reach the specified preload at the same time. In the elastic stage, the preload, the tightening torque and the tightening angle are proportional. For a group of screws tightened on the same connected part, when they are tightened to the same torque, if the preload of each screw is consistent, the angle they are tightened into should also be the same. It is relatively simple to tighten multiple screws to the specified torque at the same time, but the actual preload of the screw may not be the same. When the tightening torque is equal, the dispersion of the preload and the dispersion of the tightening angle are equal, so the dispersion of the final tightening angle can be used as the qualified judgment standard of synchronous tightening. The dispersion can be measured by the variance or standard deviation of the tightening angle, and the specific value is set according to the actual demand. When the variance or standard deviation of the tightening angle is less than or equal to the set value, it is determined that the multi-axis synchronous tightening is qualified; otherwise, it is unqualified.

[0031] In step 1, when the screw is fitted and tightened, the magnetic attraction of the sleeve is changed by changing the current in the electromagnetic clutch, thereby controlling the torque when the screw is tightened. The screw is in the form of diagonal screwing when the screw is fitted and tightened, and the levelness of the PCB board is maintained. When the screws are tightened in diagonal form, the electromagnetic clutch is divided into two groups in diagonal form, the first group of electromagnetic clutches is first energized, the first group of electromagnetic clutches drives the corresponding sleeve to rotate, and the first group of screws is tightened, when the first group of screws is tightened to the expected torque, the second group of electromagnetic clutches is energized, the second group of screws starts to tighten and reaches the expected torque, the current in the first group of electromagnetic clutches is increased, so that the first group of screws is tightened to the rated torque, then the second group of electromagnetic clutches is increased, the second screw is tightened to the rated torque, and the tightening torque is detected by the torque detector; the current size of the electromagnetic clutch and the speed of the driving gear are matched to realize preliminary tightening and improve efficiency, and finally the control precision is improved. The current controls the torque of multiple sleeves, and the current control adopts PWM technology, which is a very effective technology for using digital output of a microprocessor to control analog circuits, and is widely used in measurement, communication, industrial control and other aspects. PWM technology involves two parameters of frequency and duty cycle. The frequency of PWM refers to the number of times the signal goes from high to low and back to high in one second, that is, how many cycles of PWM there are in one second. The duty cycle is the ratio of the time of high level to the entire cycle time in a pulse period. The control circuit diagram of PWM is shown in the accompanying Figure 4 The current size of the circuit is changed by high and low potential frequency (duty cycle) of PWM, wherein the four electromagnetic clutches are connected in parallel, the electromagnetic clutches are controlled by switches, a super capacitor is arranged in the circuit, and the capacitor charges the low-voltage load (indicator light) and the battery when the device stops working, achieving the effect of saving electricity.

[0032] The working principle of the present application is as follows: the electromagnetic clutch is started, the sleeve has magnetic attraction, the power piece drives the driving shaft body to rotate, the driving gear on the driving shaft body rotates, the driving gear drives the surrounding driven gears to rotate, the sleeve at the lower part of the driven gear rotates, the screw nut end of the screw enters the sleeve, the screw is aligned with the screw hole, multiple screws rotate at the same time, the screw is tightened, and the PCB board is installed and fixed; multiple sleeves rotate at the same time to realize simultaneous tightening of the screws, so that the PCB board can be subjected to tightening force at the same time, and the board body maintains good levelness.

[0033] The above examples only express the embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the scope of the patent, and in the present embodiment, up, down, left, right, front, back only represent their relative positions and not their absolute positions. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A control method of a PCB board synchronous tightening device, characterized in that: The application relates to a screw installation device, which comprises a shell (1), a driving shaft body (2) connected with a rotary motor is arranged in the center of the shell (1), a driving gear (3) is arranged on the driving shaft body (2) and located in the shell (1), a driven gear (4) is arranged in the shell (1) and engaged with the driving gear (3) through a rotating shaft, an electromagnetic clutch (5) is arranged at the lower part of the driven gear (4), and a sleeve (6) with a built-in torque detector is arranged at the lower part of the electromagnetic clutch (5). The method comprises the following steps: S1: based on machine vision detection, the screw thread is detected, if there is a defect, the screw thread is replaced, if the screw thread is normal, the driving gear drives the driven gear to rotate, the electromagnetic clutch is started, the sleeve generates magnetic attraction force, the sleeve finds the cap end of the screw, and the screw is clamped into the sleeve, a plurality of sleeves are moved to the corresponding screw holes, the driving shaft body rotates to drive the driving gear to rotate, the driven gear engaged with the driving gear rotates, the plurality of sleeves rotate simultaneously, and the simultaneous fitting and tightening of the plurality of screws is realized, that is, the screw cap is fitted with the PCB; S2: through machine vision detection, whether the head of the screw reaches the fitting point with the PCB is judged, if not, the screw is rotated out by reverse rotation of the sleeve, and the tightening action is repeated again, if yes, the screw is finally tightened; S3: the finally tightened screw is detected to judge whether the tightened screw meets the installation standard; In step 1, the sleeve rotates at low speed, so that the screw cap end can stably enter the sleeve, the sleeve is prevented from rotating without the screw, and the sleeve is prevented from idling during screw installation; in step 1, when the screw is fitted and tightened, the magnetic attraction force of the sleeve is changed by changing the current size in the electromagnetic clutch, and then the torque during screw tightening is controlled; when the screw is fitted and tightened, the diagonal screw tightening form is adopted, and the levelness of the PCB is maintained; when the screws are tightened in the diagonal form, the electromagnetic clutch is divided into two groups in the diagonal form, current is first input into the electromagnetic clutch in the first group, the electromagnetic clutch in the first group drives the corresponding sleeve to rotate, the screws in the first group are tightened, when the screws in the first group are tightened to the expected torque, the electromagnetic clutch in the second group is electrified, the screws in the second group start to be tightened and reach the expected torque, the current in the electromagnetic clutch in the first group is increased, so that the screws in the first group are tightened to the rated torque, then the electromagnetic clutch in the second group is increased, the screws in the second group are tightened to the rated torque, and the tightening torque is detected by the torque detector.

2. The control method of the PCB board synchronous tightening device according to claim 1, characterized in that: In step 1, when the screw is fitted and tightened, the sleeve rotates at a relatively high speed, the tightening time is reduced, and the installation efficiency is improved.

3. The control method of the PCB board synchronous tightening device according to claim 1, characterized in that: In step 2, when the screw is finally tightened, the sleeve rotates at a low speed, the screw is better tightened, and the tightening precision is improved.

Images