An automatic air tightness detection device for welded pipes

Abstract

The present invention relates to the field of automated detection technology. The technical solution is: an automated air tightness detection device for welded pipes, including an air tightness detection device and a PLC controller, characterized in that the device also includes a rack, a plurality of input racks arranged parallel to each other and tilted downward to convey welded pipes, an air tightness test mechanism installed at the end of the input rack to detect the air tightness of welded pipes, a sorting mechanism arranged next to the air tightness test mechanism to sort qualified pipes and unqualified pipes, a waste rack for receiving unqualified pipes, and a transition rack for receiving and conveying qualified pipes to the next station; the input rack, air tightness test mechanism, sorting mechanism and transition rack are arranged in sequence along the conveying direction of the welded pipe; each operating mechanism is electrically connected to the PLC controller for unified control. The device adopts a pneumatic detection method to detect the air tightness of welded pipes, avoiding the problems of rust and corrosion of welded pipes in the bubble detection method, avoiding manual detection errors, and improving product quality.

Description

Technical Field

[0001] The invention relates to the technical field of automatic detection, in particular to an automatic air tightness detection device for welded pipes. Background Art

[0002] In the production of welded pipes, the welded pipes after finishing need to be tested for air tightness. Many manufacturers use the traditional method of bubble method, which is to seal both ends of the welded pipe and immerse it in water, pass a certain pressure of gas, observe with the naked eye whether there are bubbles, and determine the leakage point according to the position of the bubble. This method can only be observed with the naked eye and cannot be described quantitatively. The test results depend to a certain extent on the experience and sense of responsibility of the testers, and are greatly affected by human factors. The results measured by different measurers will be different. In addition, putting the welded pipe to be tested in water will cause rust and corrosion of the welded pipe, and subsequent drying processes are required, which increases the workload.

[0003] The pneumatic detection method uses air as the measuring medium, and introduces air of a certain pressure into the welded pipe to be tested. Then the pressure sensor measures the air pressure value of the welded pipe after inflation and converts the differential pressure value of the two times into a leakage rate, thereby judging whether the welded pipe is leaking. This method has the advantages of high detection accuracy, low cost, simple operation, no influence of subjective factors, no pollution, and no need to dry the welded pipe after the test. Therefore, it is necessary to design a device for detecting the air tightness of welded pipes using the pneumatic detection method to overcome the defects of the bubble detection method in the prior art. Summary of the invention

[0004] The purpose of the present invention is to provide an automated air tightness detection device for welded pipes, which adopts a pneumatic detection method to detect the air tightness of welded pipes, avoiding the problems of rust and corrosion of welded pipes in the bubble detection method, and does not require a subsequent drying procedure. It can also perform air tightness detection on multiple welded pipes at the same time, and has the characteristics of high detection accuracy, low cost, simple operation, and high degree of automation. It can avoid manual detection errors and improve product quality.

[0005] The technical solution provided by the present invention is:

[0006] An automatic air tightness detection device for welded pipes, comprising an air tightness detection device and a PLC controller, characterized in that: the device also comprises a frame, a plurality of input racks arranged parallel to each other and tilted downward to convey welded pipes, an air tightness test mechanism installed at the end of the input rack to detect the air tightness of the welded pipes, a sorting mechanism arranged beside the air tightness test mechanism to sort qualified pipes and unqualified pipes, a waste rack for receiving unqualified pipes, and a transition rack for receiving and conveying qualified pipes to the next station; the input rack, air tightness test mechanism, sorting mechanism and transition rack are arranged in sequence along the conveying direction of the welded pipes; each operating mechanism is electrically connected to the PLC controller for unified control;

[0007] The airtight testing mechanism includes a transversely and horizontally arranged rotating spindle, a plurality of material-dispensing and clamping assemblies which are arranged at the end of an input stand and sequentially dispense the welded pipes from the input stand and clamp the welded pipes, two sets of turntable feeding assemblies which are respectively installed at both ends of the rotating spindle to drive the rotating spindle and drive the plurality of material-dispensing and clamping assemblies to rotate at equal angles, and a movable sealing end and a fixed sealing end which are respectively arranged at both ends of the welded pipe to seal the welded pipe; the plurality of material-dispensing and clamping assemblies are installed on the rotating spindle at equal intervals; the movable sealing end can be slidably positioned on the frame along the length direction of the rotating spindle to seal welded pipes of different lengths.

[0008] The input stand comprises a vertically arranged column whose bottom can move laterally via a rolling pair, an inclined bar frame obliquely fixed to the top of the column, a protective layer arranged on the surface of the inclined bar frame, and a stopper arranged at the end of the inclined bar frame to locate the position of the welding pipe.

[0009] The material-dipping and clamping assembly comprises a material-dipping disc fixed on a rotating spindle, at least one clamping and positioning disc coaxially arranged with the material-dipping disc and capable of rotating relative to the material-dipping disc, a first cylinder hingedly connected to the material-dipping disc and having a push rod hingedly connected to the clamping and positioning disc; the radius of the material-dipping disc is greater than the radius of the clamping and positioning disc; a plurality of first notches are evenly provided on the outer edge of the material-dipping disc, so that a plurality of material-dipping hooks for dipping the welding pipe are formed on the material-dipping disc; the right side surface of the material-dipping hook is located in the first notch and a first protrusion bent toward the inside of the first notch is provided on the side surface, and the left side surface of the material-dipping hook is located in another adjacent first notch; a plurality of second notches corresponding to the first notches are provided on the clamping and positioning disc; a second protrusion bent toward the inside of the second notch is provided in the second notch so as to cooperate with the first protrusion to clamp the welding pipe together; an arc-shaped hole extending in a circumferential direction is provided on the material-dipping disc; a hinge pin of the clamping and positioning disc and the first cylinder push rod extends into the arc-shaped hole and can move along the arc-shaped hole.

[0010] The weld pipe outlet of the material-shifting and clamping assembly is provided with an inclined plate which is inclined downward to convey the weld pipe; the end of the inclined plate is located directly above the waste rack.

[0011] The number of the clamping positioning discs and the number of the first cylinders are both two, and the two clamping positioning discs are respectively arranged on both sides of the material-diverting disc; the two first cylinders respectively drive the two clamping positioning discs to rotate synchronously.

[0012] The turntable feeding assembly includes a gear plate fixed on a rotating main shaft, a second cylinder vertically arranged below the gear plate and corresponding to the position of the teeth of the gear plate, a pawl hinged at the end of a push rod of the second cylinder and applying a unidirectional force upward to the gear plate to drive the gear plate to rotate, and a third cylinder arranged below the gear plate to limit the rotation of the gear plate; a roller is installed at the end of the push rod of the third cylinder so as to abut between two adjacent teeth of the gear plate to brake the gear plate.

[0013] The sorting mechanism comprises a sorting plate which is hinged on a frame and located above a waste material rack, and a driving cylinder which is installed on the frame and drives the sorting plate to swing around a hinge axis through a connecting rod.

[0014] The movable sealing end includes a sliding frame, a plurality of pulleys rotatably positioned at the bottom of the sliding frame to drive the sliding frame to move laterally, a plurality of fourth cylinders horizontally installed on the sliding frame, and a sealing head fixed to the end of the push rod of the fourth cylinder and sealedly connected to one end of the welding pipe; a sealing gasket is installed in the sealing head to ensure the sealing performance.

[0015] The fixed sealing end includes a fixing frame, a plurality of fifth cylinders horizontally mounted on the fixing frame, and an inflation head fixed to the end of a push rod of the fifth cylinder and sealedly connected to the other end of the welded pipe; an inflation hole is provided on the inflation head; the number of the fourth cylinder and the fifth cylinder is the same; the fourth cylinder and the fifth cylinder both correspond one-to-one to the position of the welded pipe in the first slot.

[0016] The rotating spindle is a hollow tube; an inner tube is installed in the rotating spindle; rotating joints connected to an air pump are sealed and installed on both sides of the inner tube; air inlet holes connected to the first cylinder in each material-shifting clamping assembly are correspondingly provided on the inner tube and the rotating spindle.

[0017] The beneficial effects of the present invention are:

[0018] 1. In the turntable feeding assembly of the present invention, the pawl is hinged on the second cylinder, and the pawl applies unidirectional force upward to the toothed disc, so the toothed disc can only rotate in one direction at equal angles under the push of the pawl, which is convenient for the subsequent positions of the welding pipe, the blocking cylinder and the sealing cylinder to correspond one to one, thereby improving the detection efficiency.

[0019] 2. In the material-discharging and clamping assembly of the present invention, the material-discharging plate is fixedly connected to the rotating spindle, and the material-discharging plate rotates unidirectionally driven by the rotating spindle, so as to hook the welding pipe on the input stand into the first notch; and because the clamping positioning plate and the material-discharging plate can rotate relative to each other, when the first cylinder drives the clamping positioning plate to rotate in the opposite direction relative to the material-discharging plate, the second notch on the clamping positioning plate cooperates with the first notch on the material-discharging plate to clamp the welding pipe, so as to prepare for the subsequent air tightness detection of the welding pipe.

[0020] 3. The sliding frame in the present invention can slide horizontally through the pulley, which is convenient for sealing detection of welded pipes of different lengths.

[0021] 4. The sorting mechanism in the present invention can distinguish unqualified tubes from qualified tubes, which is convenient for management.

[0022] 5. The present invention can be provided with a plurality of fourth cylinders and fifth cylinders, so as to perform air tightness detection on a plurality of welded pipes at the same time, which greatly improves the work efficiency.

[0023] 6. The present invention solves the problems of rust and corrosion of welded pipes in the bubble detection method, and does not require subsequent drying procedures, thus avoiding errors in manual detection and realizing the automation of welded pipe air tightness detection. It has high detection accuracy and efficiency, low cost, reliable operation, and good market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the main structure of the present invention.

[0025] Figure 2 The main structural diagram of the airtight test mechanism of the present invention is shown in FIG. Figure 1 left-looking direction).

[0026] Figure 3 This is a schematic diagram of the main structure of the turntable feeding assembly of the present invention.

[0027] Figure 4 This is a schematic diagram of the front structural view of the material-shifting and clamping assembly of the present invention.

[0028] Figure 5 It is a schematic diagram of the side structure of the material-shifting clamping assembly of the present invention in a clamping state.

[0029] Figure 6 This is a schematic diagram of the main structure of the input stand described in the present invention.

[0030] Figure 7 It is a schematic diagram of the main structure of the airtight test mechanism and the waste rack of the present invention.

[0031] Figure 8 It is a schematic diagram of the main structure of the sorting mechanism and the transition material rack described in the present invention.

[0032] Fig. 9 It is a schematic diagram of the cross-sectional structure of the rotating spindle of the present invention.

[0033] Fig.10 It is a left-side structural schematic diagram of the movable sealing end of the present invention.

[0034] Fig.11 It is a schematic diagram of the main structure of the movable sealing end of the present invention.

[0035] Fig.12 It is a left-side structural schematic diagram of the fixed sealing end of the present invention.

[0036] Fig.13 This is a schematic diagram of the main structure of the fixed sealing end of the present invention.

[0037] 1-frame; 2-input stand; 21-column; 22-slant bar frame; 23-protective layer; 24-block; 25-roller; 26-guide rail; 3-airtight test mechanism; 31-rotating spindle; 311-inner tube; 312-rotating joint; 313-air inlet; 32-turntable feeding assembly; 321-toothed disc; 322-second cylinder; 323-ratchet; 324-third cylinder; 325-baffle; 326-roller; 33-feeding clamping assembly; 331-feeding disc; 332-clamping positioning disc; 333 -first cylinder; 334-arc hole; 335-material picking hook; 336-first protrusion; 337-second protrusion; 338-inclined plate; 34-movable sealing end; 341-sliding frame; 342-pulley; 343-fourth cylinder; 344-sealing head; 345-sealing pad; 35-fixed sealing end; 351-fixing frame; 352-fifth cylinder; 353-inflating head; 354-inflating hole; 4-sorting mechanism; 41-sorting plate; 42-pushing cylinder; 5-waste rack; 6-transition rack; 7-welded pipe. DETAILED DESCRIPTION

[0038] The following is a further description with reference to the embodiments shown in the accompanying drawings.

[0039] like Figure 1 The welded pipe automatic air tightness detection device shown in the figure comprises a frame 1, a plurality of input racks 2, an air tightness test mechanism 3, a sorting mechanism 4, a waste rack 5, a transition rack 6, an air tightness detection device (existing equipment) and a PLC controller. The input rack, the air tightness test mechanism, the sorting mechanism and the transition rack are arranged along the conveying direction of the welded pipe 7 (i.e. Figure 1 The left and right directions (the same below) are arranged in order.

[0040] Several input racks are in the transverse direction (i.e. Figure 1 In the vertical direction (i.e. Figure 1 The welded pipe is transported to the airtight test facility in the left and right directions. The number of input racks can be determined according to the length of the weldment, and the distance between adjacent input racks is less than the length of the welded pipe. Figure 6 As shown, the input rack includes a column 21, an inclined bar frame 22, a protective layer 23 and a stopper 24. The column is arranged vertically and a roller 25 is provided at the bottom. The roller and the guide rail 26 fixed horizontally on the ground form a rolling pair so as to adjust the distance between two adjacent input racks according to the length of the welded pipe. The inclined bar frame is fixed at an angle downward on the top of the column; the inclination of the inclined bar frame is 2° to 3° to ensure that the welded pipe rolls smoothly downward along the inclined bar frame under the action of gravity. The protective layer is provided on the inclined bar frame to protect the outer surface of the welded pipe; the material of the protective layer is rubber or plastic. The stopper is provided at the end of the inclined bar frame to locate the position of the welded pipe.

[0041] like Figure 2 As shown, the airtightness test mechanism is installed at the end of the input bench and is used to detect the airtightness of the welded pipe. The airtightness test mechanism includes a rotating spindle 31, two sets of turntable feeding assemblies 32, a plurality of material-dispensing clamping assemblies 33, a movable sealing end 34 and a fixed sealing end 35. The rotating spindle is arranged horizontally and transversely. The airtightness test mechanism also includes a booster pump, a pressure reducing valve, an exhaust valve, an intake valve, a high-precision pressure gauge, a pressure sensor, and a digital display (all of which are conventional airtightness detection devices, which can be purchased from outside and are not shown in the figure).

[0042] Two sets of turntable feeding components are installed at both ends of the rotating main shaft and synchronously drive the rotating main shaft to rotate in one direction. Figure 3 As shown, each set of turntable feeding components includes a toothed disc 321, a second cylinder 322, a ratchet 323 and a third cylinder 324. The toothed disc is fixed on the rotating main shaft and rotates integrally with the rotating main shaft. The second cylinder is vertically arranged below the toothed disc and corresponds to the position of the teeth of the toothed disc; the ratchet is hinged at the end of the push rod of the second cylinder, and the ratchet applies a unidirectional force upward to the toothed disc, thereby driving the toothed disc to rotate unidirectionally (in the present invention, when the second cylinder moves upward, under the blocking effect of the baffle 325, the ratchet applies an upward thrust to the toothed disc, driving the toothed disc to rotate clockwise; when the second cylinder moves downward, the ratchet rotates around the hinge axis with the second cylinder, and will not drive the toothed disc to rotate counterclockwise, thereby realizing the unidirectional rotation of the toothed disc). The third cylinder is arranged below the toothed disc; a roller 326 is installed at the end of the push rod of the third cylinder, and the roller is driven by the third cylinder to press between two adjacent teeth of the toothed disc, thereby braking the toothed disc.

[0043] Several material-dispensing and clamping assemblies are arranged at the end of the input stand and are installed on the rotating spindle at equal intervals. All material-dispensing and clamping assemblies are driven by two sets of turntable feeding assemblies to rotate with the rotating spindle, thereby dispensing and clamping the welded pipes from the input stand in sequence, in preparation for the subsequent air tightness test of the welded pipes. The number of material-dispensing and clamping assemblies can be determined according to the length and size of the welded pipes, and the spacing between adjacent material-dispensing and clamping assemblies is generally 1 to 2 meters.

[0044] like Figure 4 , Figure 5As shown, each set of material-dispensing clamping assembly includes a material-dispensing disc 331, a clamping positioning disc 332 and a first cylinder 333; in this embodiment, the number of the clamping positioning disc and the number of the first cylinder are both two. The material-dispensing disc is fixed on the rotating spindle. Two clamping positioning discs are respectively arranged on both sides of the material-dispensing disc and the two clamping positioning discs are rotatably positioned on the rotating spindle; the two clamping positioning discs and the material-dispensing disc can rotate relative to each other. The two first cylinders respectively drive the two clamping positioning discs to rotate synchronously, wherein the base of the first cylinder is hinged to the material-dispensing disc and its push rod is hinged to the corresponding driven clamping positioning disc; the material-dispensing disc is provided with an arc-shaped hole 334 extending in the circumferential direction, and a hinge pin is inserted into the arc-shaped hole. After the two ends of the hinge pin are respectively suspended to the outside of the arc-shaped hole, a clamping positioning disc and a first cylinder push rod are respectively hinged at the same time (the hinge pin is hinged to the two clamping positioning discs and the two first cylinder push rods). During operation, the hinge pin moves along the arc hole driven by the first cylinder, thereby driving the two clamping positioning plates to swing relative to the material-dispensing plate.

[0045] The radius of the material-diverting plate is greater than the radius of the clamping and positioning plate. The outer edge of the material-diverting plate is evenly provided with a plurality of (eight in the figure) first notches, thereby forming a plurality of ( Figure 4 There are eight (eight in the figure) material picking hooks 335 for picking up the welded pipe; the right side of the material picking hook is located in the first notch, and the side is provided with a first protrusion 336 bent toward the inside of the first notch, and the left side of the material picking hook is located in another adjacent first notch and the side is provided with an inclined surface. Each clamping positioning plate is provided with a plurality of (eight in the figure) second notches corresponding to the first notches; the second notch is provided with a second protrusion 337 bent toward the inside of the second notch so as to cooperate with the first protrusion to clamp the welded pipe together, and the inner wall on the other side is provided with an inclined surface. During operation, the two first cylinders contract. At this time, the material disc and the two clamping positioning discs are an integral whole. The two sets of turntable feeding assemblies drive the rotating spindle to rotate 45°, and the material hook on the material disc pulls a welding pipe from the input stand to the first notch; then the two sets of turntable feeding assemblies continue to rotate, and the material disc is driven to rotate 45° again by the rotating spindle, and the next material hook pulls the next welding pipe from the input stand into the corresponding first notch (a maximum of four welding pipes can be stored in the material disc of this embodiment); then the two first cylinders extend, driving the two clamping positioning discs to rotate in the opposite direction relative to the material disc, so that the second notch on the clamping positioning disc cooperates with the first notch on the material disc and clamps the welding pipe, preparing for the subsequent air tightness detection of the welding pipe.

[0046] The movable sealing end and the fixed sealing end are respectively arranged at both ends of the welded pipe for sealing the welded pipe. During operation, the sliding frame can adjust the distance between the sliding frame and the fixed sealing end according to the length of the welded pipe, so as to perform airtightness detection on welded pipes of different lengths.

[0047] like Fig.10 ,11 As shown, the movable sealing end includes a sliding frame 341, a pulley 342, a fourth cylinder 343 and a plugging head 344. Four pulleys are rotatably mounted at the bottom of the sliding frame to facilitate the lateral movement of the sliding frame to adapt to welding pipes of different lengths. The fourth cylinder is horizontally mounted on the sliding frame. The plugging head is fixed to the end of the push rod of the fourth cylinder so as to be sealed and connected to one end of the welding pipe; a sealing gasket 345 is installed in the plugging head to ensure sealing performance.

[0048] like Fig.12 , 13 As shown, the fixed sealing end includes a fixing frame 351, a fifth cylinder 352 and an inflation head 353. The fixing frame is fixed on the ground. The fifth cylinder is horizontally mounted on the fixing frame. The inflation head is fixed to the end of the push rod of the fifth cylinder so as to be sealed and connected with the other end of the welding pipe. An inflation hole 354 is provided on the inflation head to facilitate the booster pump (not shown) to inflate the welding pipe through the inflation hole. The number of the fourth cylinder and the fifth cylinder is the same, and in this embodiment, there are four of them, so as to simultaneously perform air tightness detection on multiple welding pipes. The four fourth cylinders and the four fifth cylinders correspond one-to-one to the four welding pipe positions in the first notch.

[0049] like Figure 7 As shown, the weld pipe outlet of the material-selecting and clamping assembly is provided with an inclined plate 338 that tilts downward to convey the weld pipe; the end of the inclined plate is located directly above the waste rack so that unqualified pipes can be conveyed into the waste rack. Figure 8 As shown, the sorting mechanism includes a sorting plate 41 and a pushing cylinder 42. One end of the sorting plate is hinged on the frame, and the other end is located above the waste rack and can be connected to the inclined plate. The pushing cylinder is installed on the frame, and the pushing cylinder drives the sorting plate to rotate through the connecting rod. In the initial position, the sorting plate is connected to the inclined plate, and the inclination angle of the sorting plate is the same as the inclination angle of the inclined plate. When the welded pipe is a defective pipe, the pushing cylinder extends to drive the sorting plate to swing upward ( Figure 1 The waste rack is opened to allow unqualified pipes to fall into the waste rack. When the welded pipe is a qualified pipe, the sorting plate is closed above the waste rack, and the welded pipe rolls along the inclined plate and the sorting plate to the transition rack. The transition rack is connected to the end of the sorting plate to receive and transfer qualified pipes to the next station.

[0050] like Fig. 9As shown, in order to prevent the air pipe of the first cylinder in each material-shifting clamping assembly from getting entangled during the rotation of the toothed disc, the rotating main shaft is set as a hollow tube. An inner tube 311 is installed in the rotating main shaft; rotary joints 312 connected to the air pump are sealed and installed on both sides of the inner tube; and air inlet holes 313 connected to the first cylinder in each material-shifting clamping assembly are correspondingly provided on the inner tube and the rotating main shaft. When working, the gas is connected to the first cylinder through the air pipe joint from the inner tube in the rotating main shaft, thereby driving each first cylinder to operate simultaneously.

[0051] All of the above operating mechanisms such as cylinders, airtight detection devices, airtight testing mechanisms, sorting mechanisms, input racks, waste racks, transition racks, etc. are electrically connected to a PLC controller (not shown in the figure) to ensure the coordination of the working of each mechanism.

[0052] The working mode of the present invention is as follows:

[0053] The welded pipes roll down slowly and neatly along the surface of the input stand and stop at the block. The two sets of turntable feeding assemblies drive the rotating spindle to rotate 45°, and the pick-up hook on the pick-up plate picks a welded pipe from the input stand to the first notch; then the two sets of turntable feeding assemblies continue to rotate, and the rotating spindle drives the pick-up plate to rotate 45° again, and the next pick-up hook picks the next welded pipe from the input stand into the corresponding first notch. Up to four welded pipes can be picked up and tested for air tightness at the same time. Then all the first cylinders extend at the same time, driving the clamping positioning plate to swing in the opposite direction relative to the pick-up plate, so that the second notch on the clamping positioning plate matches the first notch on the pick-up plate and clamps the welded pipe.

[0054] After the material clamping assembly clamps the welded pipe, the fourth cylinder and the fifth cylinder drive the inflation head and the plugging head to seal the corresponding welded pipe respectively. The booster pump pressurizes the low-pressure air to 1.5MPa high-pressure air, and the pressure required for air tightness detection is reached after the precision pressure reducing valve reduces the pressure. The exhaust valve is closed and the intake valve is opened. When the inflation pressure reaches the set requirement, the inflation is stopped and the intake valve is closed at the same time. The pressure sensor measures the air pressure value of the welded pipe after inflation. The high-precision pressure gauge directly converts the test results into leakage and displays them through the digital display, thereby determining whether the welded pipe is qualified. The whole process is fully automated, which greatly enhances work efficiency and avoids the influence of human factors. In addition, the use of high-precision pressure detectors greatly improves the detection accuracy, meets the requirements of high-precision air tightness detection of welded pipes, and the detection accuracy can reach ±5Pa.

[0055] After the airtight test, the welded pipes are sent out through the inclined plate in turn. If the airtight test fails, the push cylinder on the transition rack drives the sorting plate to rise, and the welded pipe falls into the waste rack. If the welded pipe airtight test passes, the sorting plate rolls directly onto the transition rack and enters the next station through the transition rack.

[0056] Finally, it should be noted that the above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and many variations are possible. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. An automatic air tightness detection device for welded pipes, comprising an air tightness detection device and a PLC controller, characterized in that: The device also includes a frame (1), a plurality of input racks (2) arranged parallel to each other and tilted downward for conveying welded pipes (7), an airtightness test mechanism (3) installed at the end of the input rack for detecting the airtightness of the welded pipe, a sorting mechanism (4) arranged next to the airtightness test mechanism for sorting qualified pipes from unqualified pipes, a waste rack (5) for receiving unqualified pipes, and a transition rack (6) for receiving and conveying qualified pipes to the next station; the input rack, airtightness test mechanism, sorting mechanism and transition rack are arranged in sequence along the conveying direction of the welded pipe; each operating mechanism is electrically connected to a PLC controller for unified control; The airtight test mechanism comprises a transversely and horizontally arranged rotating spindle (31), a plurality of material-dispensing clamping assemblies (33) arranged at the end of an input stand and dispensing the welded pipe from the input stand in sequence and clamping the welded pipe, two sets of turntable feeding assemblies (32) respectively installed at both ends of the rotating spindle to drive the rotating spindle and drive the plurality of material-dispensing clamping assemblies to rotate at equal angles, and a movable sealing end (34) and a fixed sealing end (35) respectively arranged at both ends of the welded pipe to seal the welded pipe; the plurality of material-dispensing clamping assemblies are installed on the rotating spindle at equal intervals; the movable sealing end can be slidably positioned on the frame along the length direction of the rotating spindle to seal welded pipes of different lengths; The input stand comprises a vertically arranged column (21) whose bottom is laterally movable via a rolling pair, an inclined bar frame (22) obliquely fixed to the top of the column, a protective layer (23) arranged on the surface of the inclined bar frame, and a stopper (24) arranged at the end of the inclined bar frame to locate the position of the welded pipe; The material-digging and clamping assembly comprises a material-digging disc (331) fixed on a rotating main shaft, at least one clamping and positioning disc (332) coaxially arranged with the material-digging disc and capable of rotating relative to the material-digging disc, and a first cylinder (333) whose base is hinged to the material-digging disc and whose push rod is hinged to the clamping and positioning disc; the radius of the material-digging disc is greater than the radius of the clamping and positioning disc; a plurality of first notches are evenly arranged on the outer edge of the material-digging disc, thereby forming a plurality of material-digging hooks (335) on the material-digging disc for dipping the welding pipe; the right side surface of the material-digging hook is located in the first notch and the side surface is A first protrusion (336) is provided on the surface and bent toward the inside of the first notch, and the left side surface of the material-discharging hook is located in another adjacent first notch; a plurality of second notches corresponding to the first notches are provided on the clamping positioning disk; a second protrusion (337) is provided in the second notch and bent toward the inside of the second notch so as to cooperate with the first protrusion to clamp the welded pipe together; an arc-shaped hole (334) extending in a circumferential direction is provided on the material-discharging disk; a hinge pin between the clamping positioning disk and the first cylinder push rod extends into the arc-shaped hole and can move along the arc-shaped hole.

2. The welded pipe automatic air tightness detection device according to claim 1 is characterized in that: The weld pipe outlet of the material-selecting and clamping assembly is provided with an inclined plate (338) that tilts downwards to convey the weld pipe; the end of the inclined plate is located directly above the waste rack.

3. The welded pipe automatic air tightness detection device according to claim 2 is characterized in that: There are two clamping and positioning discs and two first cylinders, and the two clamping and positioning discs are respectively arranged on both sides of the material-diverting disc; the two first cylinders respectively drive the two clamping and positioning discs to rotate synchronously.

4. The welded pipe automatic air tightness detection device according to claim 3 is characterized in that: The turntable feeding assembly comprises a toothed disc (321) fixed on a rotating main shaft, a second cylinder (322) vertically arranged below the toothed disc and corresponding to the position of the teeth of the toothed disc, a pawl (323) hinged to the end of a push rod of the second cylinder and applying a unidirectional force upward to the toothed disc to drive the toothed disc to rotate, and a third cylinder (324) arranged below the toothed disc to limit the rotation of the toothed disc; a roller (326) is installed at the end of the push rod of the third cylinder so as to abut between two adjacent teeth of the toothed disc to brake the toothed disc.

5. The automatic air tightness detection device for welded pipes according to claim 4 is characterized in that: The sorting mechanism comprises a sorting plate (41) hinged on a frame and located above a waste material rack, and a driving cylinder (42) mounted on the frame and driving the sorting plate to swing around a hinge axis via a connecting rod.

6. The welded pipe automatic air tightness detection device according to claim 5, characterized in that: The movable sealing end comprises a sliding frame (341), a plurality of pulleys (342) rotatably positioned at the bottom of the sliding frame to drive the sliding frame to move laterally, a plurality of fourth cylinders (343) horizontally mounted on the sliding frame, and a plugging head (344) fixed to the end of a push rod of the fourth cylinder and sealedly connected to one end of the welding pipe; a sealing gasket (345) is installed in the plugging head to ensure sealing performance.

7. The welded pipe automatic air tightness detection device according to claim 6 is characterized in that: The fixed sealing end comprises a fixing frame (351), a plurality of fifth cylinders (352) horizontally mounted on the fixing frame, and an inflation head (353) fixed to the end of a push rod of the fifth cylinder and sealedly connected to the other end of the welded pipe; an inflation hole (354) is provided on the inflation head; the number of the fourth cylinders and the fifth cylinders is the same; and the fourth cylinders and the fifth cylinders both correspond one-to-one to the positions of the welded pipes in the first notch.

8. The welded pipe automatic air tightness detection device according to claim 7 is characterized in that: The rotating main shaft is a hollow tube; an inner tube (311) is installed in the rotating main shaft; rotating joints (312) connected to an air pump are respectively sealed and installed on both sides of the inner tube; and air inlet holes (313) connected to the first cylinders in each material-shifting clamping assembly are correspondingly provided on the inner tube and the rotating main shaft.

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