Nut detection apparatus and method

Abstract

The application relates to the technical field of nut detection, and discloses a nut detection device and method, which comprises an operation table and a detection clamp electrically connected to the operation table; the detection clamp comprises a detection unit for detecting nuts and a clamping unit for fixing workpieces; the detection unit is electrically connected to the clamping unit; the detection unit comprises a positioning pin structure and a detection structure; the positioning pin structure is used for positioning nuts on the workpieces; and the detection structure is used for detecting the nuts on the workpieces; the detection structure and the positioning pin structure are oppositely arranged on the two sides of the nuts on the workpieces; the positioning pin structure comprises a positioning pin and a control assembly; and the control assembly drives the positioning pin to abut against or be separated from the nuts. The application improves detection accuracy and ensures smooth welding.

Description

Technical Field

[0001] The present invention relates to the technical field of nut detection, and in particular to a nut detection device and method. Background Art

[0002] In some assembly processing steps of automobiles, it is usually necessary to form the base material first, and then clamp and weld the formed workpiece. When welding parts such as the front subframe, front longitudinal beam, and rear longitudinal beam, nuts need to be set in predetermined places. Sometimes other parts need to be welded at the places where the nuts are set. Once welded, the places where the nuts are set cannot be adjusted. Therefore, the set nuts need to be inspected before welding to avoid missing nuts, which will cause the workpiece to loosen during subsequent clamping, and even affect the serious situation of being unable to complete the subsequent product assembly.

[0003] In the inspection of large parts, a large number of nuts need to be inspected, and automatic sensing detection is usually used for inspection. In order to improve the detection accuracy and reduce the false detection rate, the existing technology is also constantly improving the accuracy of the detection device. However, when inspecting hundreds of detection points in large parts, false detection and missed detection will still occur, resulting in missed nuts, making it impossible to improve the detection accuracy.

[0004] Therefore, in order to solve the problem that nut detection is inaccurate and false detection and missed detection are prone to occur during nut detection, it is now necessary to provide a nut detection device and method. Summary of the Invention

[0005] The present invention aims to provide a nut detection device and method to solve the problem of inaccurate nut leakage detection in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention is used to provide a nut detection device. After fixing a workpiece, the nut is detected by retracting the positioning pin, thereby avoiding the situation where the positioning pin is mistakenly detected as a nut, thereby ensuring the detection accuracy. Specifically, the nut detection device includes an operating table and a detection fixture electrically connected to the operating table; the detection fixture includes a detection unit for detecting the nut and a clamping unit for fixing the workpiece; the detection unit is electrically connected to the clamping unit; the detection unit includes a positioning pin structure and a detection structure, the positioning pin structure is used to position the nut on the workpiece, and the detection structure is used to detect the nut on the workpiece; the detection structure and the positioning pin structure are arranged on both sides of the workpiece nut; the positioning pin structure includes a positioning pin and a control component, and the control component drives the positioning pin to abut or disengage with the nut.

[0008] The principles and advantages of this solution are:

[0009] When inspecting nuts, especially on large parts with numerous nut holes, even by increasing the sensitivity of the detection switch, missed detections can occur, and the anomaly won't be discovered until later in processing. The inventors have long believed that this is due to issues with the detection switch's configuration or insufficient sensitivity. However, after repeated testing, the inventors discovered that missed or false detections are not caused by a sensitivity issue, but rather by the fact that during the inspection process, it's easy to mistakenly detect a locating pin as a nut, leading to missed or false detections.

[0010] Because the nut is hollow and small in size, and the nut is not completely fixed in the hole, it is difficult for the detection switch to accurately control the detection point during detection so that the detection point is directly opposite the nut. Therefore, the detection point is usually selected at the widest diameter of the nut. However, this detection method can easily lead to deviation in the detection point, causing the locating pin that abuts the nut to be identified during detection, and then the missing nut will be judged as qualified, resulting in false detection.

[0011] Because the nut inspection is performed before the parts are welded, welding can be carried out directly after the inspection is correct. Therefore, in order to ensure the accuracy of the parts welding, the position of the parts must be fixed and not shifted throughout the entire process. Due to the structural design of the parts and to facilitate subsequent processing, the clamping and fixation of the parts are based on the opening position of the parts. The opening position is generally also a position that requires pre-embedded nuts or pre-processing, so when the parts are clamped, the nut hole position is positioned by a locating pin and fixed with a fixture. At the same time, when the nuts are inspected, the locating pins are also needed to locate the nuts, so the locating pins play a dual role of locating and positioning.

[0012] Therefore, conventional thinking would believe that before the welding work is completed, the relative position of the workpiece needs to be guaranteed to be stable, and once the welding is completed, it will not be able to be adjusted, so it is necessary to ensure that the welding is correct. However, it only takes a few seconds to detect the nut, so the welding and the detection of the nut will be considered to be carried out simultaneously. Therefore, it will be believed that the clamping unit cannot be moved during the entire welding process. However, the present application overcomes the conventional thinking, and after verification, it is found that the action of detecting the nut within a few seconds before welding can be separated. Because the action amplitude of the detection nut is small and the time is short, if the locating pin is withdrawn in a short time, it will not affect the stability of the workpiece, and there are also fixed structures such as fixtures for clamping, so that the stability of the workpiece can be fully guaranteed. After the detection is completed, the locating pin is restored and fixed in time before welding. This avoids the situation where the locating pin is mistakenly detected as a nut when detecting the nut, greatly improving the detection accuracy, and the extremely short operation time of withdrawing the pin will not affect the overall welding efficiency.

[0013] Therefore, the present application uses an operating table to directly control the operation of the inspection fixture to fix the workpiece before testing, which is more flexible and convenient. The nut of the workpiece is then inspected by the inspection unit 4. During the inspection, the locating pin is first retracted through the control component so that the locating pin exits the nut hole in a short time. Then the nut is inspected by the control inspection unit 4. After the inspection structure is completed, the locating pin is promptly restored, thereby avoiding the situation where the locating pin is mistakenly detected as a nut, causing a false detection. At the same time, the fixed structure can further ensure the stability of the workpiece, prevent the workpiece from being offset and affecting the subsequent welding operation, thereby improving the inspection accuracy while ensuring smooth welding.

[0014] Preferably, as an improvement, the detection unit includes a support frame, and the positioning pin structure and the detection structure are respectively arranged on both sides of the support frame. The positioning pin structure and the detection structure cooperate with each other to facilitate nut positioning without affecting nut detection.

[0015] Preferably, as an improvement, the control assembly includes a three-axis cylinder and multiple molded pieces, and the positioning pin is connected to the three-axis cylinder via the multiple molded pieces; the detection structure includes a clamping jaw assembly and a first cylinder connected to the clamping jaw assembly. The three-axis cylinder ensures rapid control of the positioning pin's extension and retraction, improving the efficiency of positioning pin control; the cylinder flexibly controls the clamping jaw assembly.

[0016] Preferably, as an improvement, the support frame is further provided with a Z-shaped piece, a guide block is provided on the Z-shaped piece, a through hole is provided at the upper end of the guide block, and the positioning pin is movably inserted through the through hole.

[0017] Preferably, as an improvement, the detection fixture includes multiple, the operating table includes at least one set of control modules, and the control modules are electrically connected to the detection fixtures. Multiple detection fixtures can be used to detect and fix workpieces of various specifications, thereby improving the versatility of the detection fixture.

[0018] Preferably, as an improvement, the system further comprises a testing platform, the testing fixture is disposed on the testing platform, and the operating platform is disposed on one side of the testing platform; a plurality of universal wheels are disposed below the testing platform. This allows for flexible positioning of the testing fixture via the testing platform, thereby meeting the testing requirements of various workpieces and improving testing efficiency. The universal wheels also facilitate the movable transportation of the testing device, facilitating storage and transportation.

[0019] Preferably, as an improvement, a display module is further included, the display module is electrically connected to the detection fixture, and a corresponding number is set on each group of the detection fixtures. The display module can quickly find the position of the nut with abnormal detection, which is convenient for the operator to deal with it in time.

[0020] Accordingly, the present invention also provides a nut detection method, applicable to the aforementioned nut detection device. The method comprises: controlling a positioning pin to retract and withdraw from a nut hole for 2-3 seconds before detecting a nut on a workpiece; using a detection switch to detect the hole to determine whether a nut is present; if a nut is present, controlling the positioning pin to extend and return, and welding the workpiece; and issuing an abnormality notification if a nut is not present.

[0021] Preferably, as an improvement, the positioning pin is controlled to move telescopically by PLC, thereby realizing intelligent control and making operation simpler and more convenient.

[0022] Preferably, as an improvement, the workpiece is first positioned and fixed by a positioning pin and then clamped by a clamping unit, thereby improving the stability of the workpiece and quickly positioning and fixing the nut. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural schematic diagram of a nut detection device of the present invention;

[0024] Figure 2 This is a schematic diagram of the workpiece structure of a nut detection device of the present invention;

[0025] Figure 3 This is a schematic structural diagram of a nut detection device of the present invention in a clamping state of a detection fixture;

[0026] Figure 4 This is a schematic structural diagram of a fourth detection fixture of a nut detection device of the present invention;

[0027] Figure 5 This is a schematic structural diagram of a clamping unit of a nut detection device according to the present invention;

[0028] Figure 6 This is a structural schematic diagram of a nut detection device according to the present invention in a sheet assembly state 1;

[0029] Figure 7 This is a structural schematic diagram of a nut detection device according to the present invention in a second die assembly state;

[0030] Figure 8 This is a structural schematic diagram of a nut detection device according to the present invention in a first clamping state of a detection unit;

[0031] Figure 9 This is a structural schematic diagram of a detection unit state 1 of a nut detection device of the present invention;

[0032] Figure 10 This is a structural schematic diagram of a detection unit state 2 of a nut detection device according to the present invention;

[0033] Figure 11This is a structural schematic diagram of a detection unit state three of a nut detection device according to the present invention;

[0034] Figure 12 This is a structural schematic diagram of a nut detection device according to the present invention in a second clamping state of a detection unit;

[0035] Figure 13 This is a partially enlarged view of the clamping state of the detection unit of a nut detection device of the present invention. DETAILED DESCRIPTION

[0036] The following is further described in detail through specific implementation methods:

[0037] The figure marks in the drawings of the specification include: detection table 1, detection fixture 2, control module 3, detection unit 4, clamping unit 5, detection switch 7, positioning pin structure 9, workpiece 10, detection structure 11, positioning pin 12, control component 13, three-axis cylinder 14, first cylinder 15, clamping jaw assembly 16, operating table 17, first detection fixture 19, fourth detection fixture 18, second detection fixture 41, third detection fixture 42, support frame 51, mounting hole 53, second cylinder 57, plate 59, gasket 60, first L-shaped plate 30, second L-shaped plate 31, straight rod plate 32, positioning hole 33, Z-shaped plate 34, guide block 35, through hole 36, mounting plate 21, connecting block 22, rotating pin 23, U-shaped rotating arm 24, T-shaped plate 25, clamping plate 26.

[0038] Example 1

[0039] Basically as attached Figure 1 As shown: A nut detection device is used to perform leak-proof detection on the set nuts before welding, improve the detection accuracy, and reduce the missed detection rate. Specifically, it includes a detection platform 1 with an overall rectangular structure, and a plurality of sets of detection fixtures 2 that can be flexibly disassembled and assembled are installed on the detection platform 1 by bolts. In this embodiment, the number of detection fixtures 2 is selected and used according to the specifications of the actual detection workpiece 10, and it is sufficient to meet the detection requirements and facilitate operation. An operating table 17 is also installed on one side of the detection platform 1, and the operating table 17 includes a plurality of groups of control modules 3 corresponding to the detection fixtures 2, and the control modules 3 are electrically connected to the detection fixtures 2. Four universal wheels are also installed under the detection platform 1 to facilitate the movement and transportation of the detection platform 1. In this embodiment, the control module 3 adopts a PLC programmable electrical controller, and cooperates with the connected three-position solenoid valve. The valve core of the three-position solenoid valve is electrically controlled by the PLC to move left or right to realize electrical signal transmission, thereby realizing the transmission of instructions to the corresponding detection fixture 2.

[0040] Specifically, combined with Figure 2 The workpiece 10 structure shown and Figure 3In the clamping state shown, in this embodiment, the detection fixture 2 is divided into four groups, wherein the fixture structures installed at both ends of the workpiece 10 are the same and are symmetrically arranged, namely the first detection fixture 19 and the fourth detection fixture 18. The fixtures located in the middle of the workpiece 10 are respectively the second detection fixture 41 and the third detection fixture 42. Each group of detection fixtures has a similar structure and includes at least one clamping unit 5 and a detection unit 4, and the detection unit 4 is electrically connected to the clamping unit 5. The difference is that according to the structure of the workpiece 10, the second detection fixture 41 only includes one clamping unit 5.

[0041] Specifically, the fourth detection fixture 18 is used as an example for description. Figure 4 As shown, the fourth detection fixture 18 includes three clamping units 5 and one detection unit 4; the three clamping units 5 are arranged opposite to each other in a triangle shape, and form a cross arrangement with the detection unit 4.

[0042] Specifically, as attached Figure 5 The clamping unit 5 shown includes a support frame 51 fixed to the inspection table 1 by bolts, a second cylinder 57 is mounted on the support frame 51, a U-shaped rotating arm 24 is mounted at the output end of the second cylinder 57, and a clamping jaw assembly 16 is mounted on the U-shaped rotating arm 24. The clamping jaw assembly 16 is composed of a plurality of shaped plates 59 of different shapes according to the structure and position of the workpiece 10 to be clamped, and the shaped plates 59 are fixedly connected by bolts. In this embodiment, the shaped plates 59 can be increased or decreased according to the structure of the workpiece to be clamped, thereby improving the versatility of the clamping jaw assembly 16.

[0043] Specifically, as attached Figure 6 The illustrated assembly state of the sheet 59 is one of the following: each sheet 59 is provided with a plurality of mounting holes 53, through which the jaw assembly 16 of various shapes can be assembled. At the same time, by adjusting the connection position of the mounting holes 53, the position and distance between the sheets 59 can be adjusted to improve versatility. Figure 7 As shown, a gasket 60 can be further provided at the connection between each of the shaped pieces 59 to adjust the spacing between each of the shaped pieces 59 for fine-tuning. The thickness of the gasket 60 is 5 mm to improve applicability.

[0044] Specifically, the first detection fixture 19 and the fourth detection fixture 18 have the same structure; the second detection fixture 41 differs from the fourth detection fixture 18 in that it only includes one clamping unit 5; the third detection fixture 42 differs from the fourth detection fixture 18 in that it includes one detection unit 4 and two clamping units 5, and the difference between the clamping units 5 included in the above detection fixtures is only that the structure of the clamping jaw assembly 16 is different due to the different structure of the workpiece 10, and the structure of the sheet 59 and the assembly relationship used are different.

[0045] Specifically, as attached Figure 8The detection unit 4 shown in the figure includes a support frame 51, which is mounted on the detection platform 1 by bolts. A positioning pin structure 9 and a detection structure 11 are respectively mounted on both sides of the support frame 51. The positioning pin structure 9 is used to locate the nut hole of the workpiece 10 and find the nut position to ensure the accuracy of the detection hole. The detection structure 11 is used to detect the located nut. Specifically, in combination with the attached Figure 9 The positioning pin structure 9 includes a control component 13 and a positioning pin 12. The control component 13 is installed on one side of the support frame 51, and the positioning pin 12 is installed at the front end of the control component 13. The control component 13 drives the positioning pin 12 to extend and retract. In this embodiment, the control component 13 includes a three-axis cylinder 14 and a plurality of profiles 59 connected to the front end of the piston rod of the three-axis cylinder 14. Figure 9 As shown, multiple pieces 59 include a first L-shaped piece 30 connected to the piston rod, and a second L-shaped piece 31 is connected to the outside of the short axis of the first L-shaped piece 30 through a pin, and the short axis end of the second L-shaped piece 31 is located at the front end of the first L-shaped piece 30, and a straight rod piece 32 is horizontally installed above the short axis of the second L-shaped piece 31 through a pin, and a positioning hole 33 is opened at one end of the straight rod piece 32, and the positioning pin 12 is fixed in the positioning hole 33. The position of the positioning pin 12 can be flexibly adjusted by combining multiple pieces 59, so that it is convenient to fine-tune according to the position of the nut, and the applicability is wider.

[0046] At the same time, combined Figure 9 、 Figure 10 and Figure 11 As shown, a Z-shaped piece 34 is also provided at the front end of the support frame 51, and a guide block 35 is installed at the upper end of the Z-shaped piece 34. A through hole 36 is provided at the upper end of the guide block 35. The front end of the locating pin 12 can pass through the through hole 36 and abut against the nut hole of the workpiece 10, so that the locating pin 12 is inserted into the nut. In this embodiment, an electrical signal is sent to the three-axis cylinder 14 through the control module 3. After receiving the signal, the three-axis cylinder 14 changes the three-axis cylinder 14 from the intake (or exhaust) state to the exhaust (or intake) state, thereby driving the piston rod of the three-axis cylinder 14 to move, and then driving the first L-shaped piece 30, the second L-shaped piece 31 and the straight rod piece 32 to move forward or backward in turn, so that the locating pin 12 can be extended and retracted in the through hole 36 of the guide block 35, completing the retraction or extension of the locating pin 12. In this embodiment, the use of a combination of multiple pieces 59 can better meet the precise positioning and adjustment of the locating pin 12, and the position of the locating pin 12 can be fine-tuned to meet the precise alignment of the nut hole.

[0047] Specifically, as attached Figure 11 and Figure 12As shown, the detection structure 11 is fixedly mounted on the other side of the support frame 51 via a mounting plate 21. The detection structure 11 includes a first cylinder 15 and a clamping jaw assembly 16 mounted at the front end of the first cylinder 15. The clamping jaw assembly 16 includes a connecting block 22, on which a rotating pin 23 is mounted. The rotating pin 23 is a square rod structure. The rotating pin 23 passes through the connecting block 22 and is exposed on both sides of the connecting block 22. A U-shaped rotating arm 24 is clamped at both ends of the rotating pin 23. The rotating pin 23 is movably connected to the piston rod of the first cylinder 15, so that the first cylinder 15 drives the rotating pin 23 to rotate, thereby driving the U-shaped rotating arm 24 to rotate.

[0048] A T-shaped piece 25 is mounted on the front end of the U-shaped rotating arm 24 via a pin, and a clamping piece 26 is mounted on the front end of the T-shaped piece 25 via a pin. One end of the clamping piece 26 is a U-shaped clamping claw structure, and a detection switch 7 is movably hinged in the U-shaped clamping claw structure. Figure 12 As shown, the U-shaped rotating arm 24 is rotated by rotating the rotating pin 23, thereby driving the T-shaped piece 25 and the clamping piece 26 to rotate in turn, so that the U-shaped clamping claw structure at one end of the clamping piece 26 abuts against the front end of the guide block 35, thereby clamping the workpiece 10. At the same time, Figure 13 As shown, the clamping plate 26 drives the detection switch 7 to approach the nut hole of the workpiece 10 for detection. Specifically, the first cylinder 15 can be controlled by an electrical signal to operate, thereby controlling the detection switch 7 to detect the located nut hole and determine whether there is a nut in the hole. The detection switch 7 is a commonly used detection switch 7 device for nut leakage detection in industrial production. For example, a proximity switch is also called a proximity sensor. It can adopt an inductive proximity switch, a capacitive proximity switch, a photoelectric proximity switch, or a magnetic proximity switch. In this embodiment, the detection switch 7 adopts an inductive proximity switch model BD2-13-M8S.

[0049] At the same time, the present invention also provides a nut detection method, which is applied to the above-mentioned nut detection device, and specifically includes:

[0050] like Figure 1 、 Figure 3 、 Figure 12 and Figure 13 As shown, the workpiece 10 is first placed on the inspection fixture 2, the nut on the workpiece 10 is accurately positioned by the positioning pin 12, and then the workpiece 10 is clamped and fixed by the clamping unit 5, so that the nut hole of the workpiece 10 is between the guide block 35 and the clamping sheet 26, and corresponds to the through hole 36 on the guide block 35, to ensure that the workpiece 10 is stable and not offset.

[0051] Before performing a leak-proof test on the nut on the workpiece 10, the electrical signal sent by the control module 3 controls the positioning pin 12 to retract into the through hole 36 of the guide block 35, and withdraw from the nut hole position of the workpiece 10 and wait for 2-3 seconds, and then controls the detection switch 7 to detect the hole position to determine whether there is a nut in the hole position; if there is a nut, the positioning pin 12 is controlled to extend and restore, and the welding program is started to weld the workpiece 10; if there is no nut, an abnormal prompt is issued, thereby ensuring the accuracy and precision of the nut detection.

[0052] Specifically, after the workpiece 10 is clamped on the corresponding detection fixture 2, the matching control module 3 is operated to transmit the set electrical signal to the three-axis cylinder 14. After receiving the electrical signal, the three-axis cylinder 14 controls the air intake or exhaust, thereby quickly controlling the positioning pin 12 to retract and exit the nut hole and wait for 2-3 seconds; at this time, the detection switch 7 detects the positioned nut hole after receiving the detectable electrical signal. When a nut is detected in the hole, a qualified signal is fed back to the control module 3. At this time, the control module 3 will send an electrical signal to the three-axis cylinder 14 again, extend and restore the positioning pin 12 in time, position and fix the nut again, and then weld. When the detection switch 7 does not detect the nut, an abnormal prompt is issued, and the machine action is stopped and switched to standby mode, and the welding process is stopped.

[0053] In this embodiment, by withdrawing the locating pin 12 in advance for 2-3 seconds, the detection switch 7 can avoid mistakenly detecting the locating pin 12 as a nut during detection, thereby judging the missing nut as qualified, greatly improving the detection accuracy. In addition, the present application cleverly separates the step of detecting the nut, and only withdraws the locating pin 12 for 2-3 seconds, quickly withdraws the locating pin 12 in a very short time, and completes the nut detection. The impact of this action on the workpiece is almost zero, and the locating pin 12 is restored in time after the detection, so that the time for the locating pin 12 to be separated from the nut is extremely short, and therefore it will not affect the stability of the workpiece 10. This method of withdrawing the locating pin 12 in advance greatly improves the accuracy of the detection, avoids the situation where the detection switch 7 mistakenly detects the locating pin 12 as a nut, improves the detection accuracy, and provides a guarantee for the subsequent workpiece assembly.

[0054] Example 2

[0055] Different from the first embodiment, this embodiment further includes a display module, which is electrically connected to the control module 3. When the detection switch 7 detects an abnormality, the abnormal situation will be prompted through the display module.

[0056] Specifically, each detection fixture 2 has its own unique identification number, and a sign is provided on the detection table 1 to easily identify the number of each detection fixture 2. The control module 3 controls the operation of the corresponding detection fixture 2 based on the unique identification number. When the absence of a nut or an abnormality is detected, the display module will display the detection fixture 2 with the corresponding number, and provide prompts through sound and flashing lights, so that the operator can intuitively and quickly find the abnormal location and take timely measures to improve detection efficiency.

[0057] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A nut detection method, characterized in that: The invention adopts a nut detection device, which includes an operating table and a detection fixture electrically connected to the operating table; the detection fixture includes a detection unit for detecting the nut and a clamping unit for fixing the workpiece; the detection unit is electrically connected to the clamping unit; the detection unit includes a positioning pin structure and a detection structure, the positioning pin structure is used to position the nut on the workpiece, and the detection structure is used to detect the nut on the workpiece; the detection structure and the positioning pin structure are arranged on both sides of the workpiece nut; the positioning pin structure includes a positioning pin and a control component, and the positioning pin is arranged on both sides of the workpiece nut; Installed on the front end of the control component, the control component drives the positioning pin to extend and retract, and to abut or disengage with the nut; the control component includes a three-axis cylinder and a plurality of profiles, and the positioning pin is connected to the three-axis cylinder through the plurality of profiles; the plurality of profiles include a first L-shaped piece connected to the piston rod, a second L-shaped piece is connected to the outside of the short axis of the first L-shaped piece through a pin shaft, the short axis end of the second L-shaped piece is located at the front end of the first L-shaped piece, and a straight rod profile piece is transversely installed above the short axis of the second L-shaped piece through a pin shaft, and a positioning hole is opened at one end of the straight rod profile piece, and the positioning pin is fixed in the positioning hole; The detection unit includes a support frame, a Z-shaped piece is provided on the support frame, a guide block is provided on the Z-shaped piece, a through hole is provided at the upper end of the guide block, the positioning pin is movably inserted into the through hole, abuts against the nut hole of the workpiece, and retracts and contracts within the through hole; The nut detection method includes controlling a positioning pin to retract and exit the nut hole for 2-3 seconds before detecting the nut on the workpiece; using a detection switch to detect the hole to determine whether there is a nut in the hole; if there is a nut, controlling the positioning pin to extend and restore, and welding the workpiece; if there is no nut, issuing an abnormal prompt.

2. A nut detection method according to claim 1, characterized in that: The positioning pin structure and the detection structure are respectively arranged on both sides of the support frame.

3. A nut detection method according to claim 1, characterized in that: The detection structure includes a clamping jaw assembly and a first cylinder connected to the clamping jaw assembly.

4. A nut detection method according to claim 1, characterized in that: The detection fixtures include a plurality of them, and the operating table includes at least one group of control modules, and the control modules are electrically connected to the detection fixtures respectively.

5. A nut detection method according to claim 4, characterized in that: It also includes a testing platform, the testing fixture is arranged on the testing platform, and the operating platform is arranged on one side of the testing platform; a plurality of universal wheels are arranged under the testing platform.

6. A nut detection method according to claim 1, characterized in that: It also includes a display module, which is electrically connected to the detection fixtures, and each group of the detection fixtures is provided with a corresponding number.

7. A nut detection method according to claim 1, characterized in that: The positioning pin is controlled to move telescopically through PLC.

8. A nut detection method according to claim 7, characterized in that: The method also includes first positioning and fixing the workpiece by means of a positioning pin, and then clamping the workpiece by means of a clamping unit.

Images