Four-way valve cover welding clamp and welding method

Abstract

The invention provides a four-way valve cover welding fixture. The four-way valve cover welding fixture comprises a base, a first fixing seat, a second fixing seat and a detection device, the detection device is movably connected with the base, so that the detection device can rotate around the first fixing seat, the height of the detection device corresponds to the top surface position of the first fixing seat, and the detection range of the detection device completely covers the annular side surface above the first fixing device through the rotation process; the invention further provides a four-way valve cover welding method corresponding to the clamp. The gap size of the welding face is accurately adjusted by detecting the gap width of the welding face through the ultrasonic detector, errors existing in the manual naked eye observation or surveying and mapping adjusting process are avoided, and the welding quality is improved. The ultrasonic detector moves along the guide rail and detects the welding surface through 360-degree rotation, so that the problem that welding flux and welding wires are difficult to enter and the welding quality is affected due to the fact that partial gaps are too small due to the fact that the welding surface is uneven is solved.

Description

Technical Field

[0001] The invention relates to the technical field of valve assembly tooling, and in particular to a four-way valve cover welding fixture and a welding method. Background Art

[0002] A four-way valve is a control valve with four interfaces. Its four valve ports are connected to four fluid pipelines respectively. The valve core of the four-way valve usually has two fluid passages that are not connected to each other. These two fluid passages are on the same plane and are connected to the four valve ports respectively. The four-way valve can control the conduction of four fluid pipelines at the same time and control the flow direction of the fluid medium in the pipelines. The use of four-way valves saves the use of two-way valves and reduces the manufacturing cost of process pipelines.

[0003] The four-way valve is also an indispensable component in refrigeration equipment. It forms a refrigeration cycle and a heating cycle through the cooperation of the coil and the compression spring, so that the refrigerant can achieve different working requirements through different circulation methods. The structure of this type of four-way valve is relatively special. For example, the Chinese invention patent CN200910135102.3 provides a four-way valve with a simple structure. Even if the high-temperature refrigerant and the low-temperature refrigerant flow close to each other, the heat loss caused by heat leakage between the two can be suppressed. The valve body is a strip structure, one of the valve ports is located on one side of the valve body, and the other three valve ports are arranged in parallel on the other side.

[0004] When producing this kind of four-way valve, after the valve body and valve cover are formed, the valve body and valve cover need to be welded to facilitate the fixing and connection of the valve body through the valve cover. During the welding process of the valve cover and the valve body, a certain gap is usually left between the welding surfaces. By leaving a certain gap, materials such as the weld, flux and welding wire can be allowed to shrink and deform freely, and at the same time, the stress and deformation caused by thermal deformation can be reduced, allowing the welding wire or flux to be fully deposited and reducing the generation of gaps and holes.

[0005] However, since the thickness of the welding surface when the valve body and the valve cover are welded is different, the gaps required to be left on the welding surfaces are also different; and the gap required between the welding surfaces is usually small, so it is generally determined by visual observation or manual measurement with a ruler in the prior art, and the flatness between the welding surfaces of some valve bodies and valve covers is poor, which makes it more likely that the weld will be too wide or too narrow when welding the welding surfaces, resulting in uneven solder input and affecting the welding effect. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a four-way valve cover welding fixture and a welding method, which solves the problem in the prior art that the flatness between the welding surfaces of some valve bodies and valve covers is poor, and it is more likely that the weld will be too wide or too narrow when welding the welding surfaces, resulting in uneven solder input and affecting the welding effect.

[0007] In a first aspect, the present invention provides a four-way valve cover welding fixture, comprising a base, a first fixing seat arranged on the base, a second fixing seat and a detection device;

[0008] The first fixing seat is movably arranged on the surface of the base, and is used to clamp the valve body of the four-way valve. A driving device is arranged at the bottom of the first fixing seat to drive it to move in the vertical direction;

[0009] The second fixing seat is mounted above the first fixing seat through a bracket, and the second fixing seat is used to clamp the valve cover of the four-way valve. The bracket is a movable structure, which can drive the second fixing seat to move in the horizontal and vertical directions respectively;

[0010] The detection device is movably connected to the base so that it can rotate around the first fixed seat. The height of the detection device corresponds to the top surface position of the first fixed seat, so that the detection device can completely cover the annular side surface above the first fixed device through the rotation process.

[0011] Furthermore, the first fixed seat includes a mounting ring, which is a vertically arranged circular ring structure, and a connecting piece is coaxially arranged at the center position of the mounting ring to fix the valve body of the four-way valve, and two horizontal clamping plates are correspondingly arranged on both sides above the connecting piece, and the clamping plates are axially symmetrically arranged relative to the central axis of the mounting ring, and the clamping plates can move relatively and synchronously, so as to adjust the spacing between the clamping plates.

[0012] Furthermore, two slide rails are provided at the bottom of the mounting ring, and the slide rails are arranged parallel to the clamping plate. A plurality of horizontal support rods are installed between the slide rails, and the support rods are perpendicular to the slide rails and movably arranged with the slide rails, so that the support rods can move horizontally along the slide rails.

[0013] Furthermore, the connecting member includes a vertically arranged limit cylinder, which is coaxially arranged at the center position of the mounting ring, and a plurality of adjustment plates are circumferentially arranged inside the limit cylinder, and the adjustment plate includes a vertical section and an inclined section, one end of the inclined section is rotatably connected to the inside of the limit cylinder, and the other end is rotatably connected to the vertical section, and a plurality of springs are arranged on one side of the vertical section close to the inner wall of the limit cylinder, and the springs are evenly arranged at equal intervals along the vertical direction.

[0014] Furthermore, the bracket includes a mounting frame horizontally arranged above the first fixing seat, the second fixing seat is arranged in the middle of the mounting frame, and a plurality of first telescopic rods are arranged on the edge of the mounting frame, and the first telescopic rods control the movement of the mounting frame in the vertical direction.

[0015] Furthermore, a transfer sleeve is provided in the mounting frame, and the transfer sleeve is arranged, and two parallel adjustment rods are also provided on the mounting frame, and the adjustment rods horizontally penetrate the side wall of the transfer sleeve, one of the adjustment rods is slidingly connected to the transfer sleeve, and the other adjustment rod is screwed to the transfer sleeve through a thread, and when the adjustment rod rotates, the transfer sleeve is driven to move along the direction of the adjustment rod.

[0016] Furthermore, the second fixing seat includes a vertically arranged fixing sleeve, the fixing sleeve is a hollow cylindrical structure, the fixing sleeve is rotatably installed inside the adapter sleeve, and can only rotate but cannot move vertically along the axial direction;

[0017] A plurality of second telescopic rods are arranged around the interior of the fixing sleeve. The second telescopic rods are arranged along the radial direction of the fixing sleeve. One end of the second telescopic rod is connected to the inner wall of the fixing sleeve, and the other end is provided with a pressing sheet.

[0018] Furthermore, one end surface of the fixed sleeve extends out of the adapter sleeve, and a driven gear is provided around the outer side of the end surface. A motor is installed on the corresponding end surface of the adapter sleeve, and a driving gear is provided at the output end of the motor. The driving gear is meshed with the driven gear to control the rotation of the driven gear and the fixed sleeve.

[0019] Furthermore, the detection device includes a horizontal guide rail arranged on the base, the guide rail is an annular structure arranged around the first fixed seat, and a slider is provided on the guide rail, and the slider can move freely along the guide rail; a vertical mounting platform is provided on the slider, and the top of the mounting platform extends to the surface of the first fixed seat, and an ultrasonic detector is provided on the top of the mounting platform. The detection direction of the ultrasonic detector is along the radial direction of the guide rail and passes above the center position of the first fixed seat.

[0020] In a second aspect, the present invention further provides a four-way valve cover welding method, comprising the following steps:

[0021] S1. Install the valve body on the first fixing seat, install the valve cover on the second fixing seat, adjust the horizontal position of the second fixing seat so that the valve body and the valve cover correspond to each other, and then drive the second fixing seat to move downward so that the welding surfaces of the valve cover and the valve body are in close contact with each other;

[0022] S2, turn on the ultrasonic detector, and then slowly adjust the second fixing seat to move upward until the gap width detected by the ultrasonic detector is exactly the same as the required welding gap width;

[0023] S3. Rotate the ultrasonic detector 360° around the first fixed seat as a whole. If the gap width detected by the ultrasonic detector meets the welding standard, the welding process can be started. If the ultrasonic detector cannot detect the gap within a certain range of arc or the gap is much smaller than the welding gap width, rotate the second fixed seat, adjust the angle of the contact surface between the valve body and the valve cover, and perform a 360° rotation test of the ultrasonic detector every time a certain angle is adjusted until the gap width detection meets the standard.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the present invention, the valve body is installed by the first fixing seat, and the valve cover is installed by the second fixing seat, so that the valve body and the valve cover are arranged correspondingly up and down, and the movement of the second fixing seat is controlled at the same time, so that the welding surfaces of the valve cover and the valve body are close to each other and a gap is left to allow materials such as the weld, flux and welding wire to shrink and deform freely. At the same time, the ultrasonic detector in the detection device emits an ultrasonic wave, which passes through the gap between the valve cover and the valve body. When the ultrasonic wave encounters the gap, a part of the energy will be reflected back. The time and amplitude of the reflected energy can reflect the depth and size of the gap, so that the width of the welding gap can be detected. When the present invention is in use, by adjusting the distance between the valve body and the valve cover, when the gap width detected by the ultrasonic detector is exactly equal to the preset welding gap width, the gap size is accurately adjusted. Thereby avoiding the errors existing in the process of manual naked eye observation or surveying and mapping adjustment, and improving the welding quality.

[0026] In addition, the ultrasonic detector in the present invention is set on the slider through the mounting platform, and moves along the guide rail with the slider. During the movement, because the connecting line between the sliders is always radial, the ultrasonic wave emitted by the ultrasonic detector is emitted to the welding surface from all angles. In this way, the welding surface can be detected through 360° rotation, avoiding the problem that some gaps are too small due to the uneven welding surface, which makes it difficult for flux and welding wire to enter, thereby affecting the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a side schematic diagram of an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of a top view of the first fixing seat in an embodiment of the present invention.

[0029] Figure 3 Schematic diagram of an axial cross section of a connecting member in an embodiment of the present invention.

[0030] Figure 4 It is a top view schematic diagram of the bracket and the second fixing seat in an embodiment of the present invention.

[0031] Figure 5It is a top view schematic diagram of the fixing sleeve in the embodiment of the present invention.

[0032] Figure 6 Schematic diagram of the structure of the detection device in the embodiment of the present invention.

[0033] In the above drawings: 1. base; 2. first fixed seat; 3. second fixed seat; 4. guide rail; 5. mounting table; 6. ultrasonic detector; 7. adapter sleeve; 11. hydraulic telescopic rod; 12. mounting frame; 13. first telescopic rod; 21. mounting ring; 22. connecting piece; 23. clamping plate; 24. third telescopic rod; 25. slide rail; 26. support rod; 31. second telescopic rod; 32. pressing plate; 41. slider; 71. motor; 121. adjusting rod; 221. limiting cylinder; 222. adjusting plate; 223. spring.

[0034] The dotted line in the figure indicates the structure that is blocked and at the bottom. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0036] like Figure 1 As shown, the embodiment of the present invention proposes a four-way valve cover welding fixture and welding method, comprising a base 1, a first fixing seat 2, a second fixing seat 3 and a detection device arranged on the base 1. The first fixing seat 2 is movably arranged on the surface of the base 1, and is used to clamp the valve body of the four-way valve. A driving device is arranged at the bottom of the first fixing seat 2 to drive it to move in the vertical direction; the second fixing seat 3 is erected above the first fixing seat 2 through a bracket, and the second fixing seat 3 is used to clamp the valve cover of the four-way valve. The bracket is a movable structure, which can drive the second fixing seat 3 to move in the horizontal and vertical directions respectively.

[0037] The valve body is installed through the first fixing seat 2, and the valve cover is installed through the second fixing seat 3, so that the valve body and the valve cover are arranged correspondingly up and down, and the movement of the second fixing seat 3 is controlled at the same time, so that the welding surfaces of the valve cover and the valve body are close to each other and a gap is left to allow materials such as welds, flux and welding wire to shrink and deform freely. The detection device is movably connected to the base 1 so that it can rotate around the first fixing seat 2. The height of the detection device corresponds to the top surface position of the first fixing seat 2, so that the detection device can completely cover the annular side surface above the first fixing device through the rotation process.

[0038] like Figure 2As shown, as a preferred embodiment, the detection device includes a horizontal guide rail 4 arranged on the base 1, the guide rail 4 is an annular structure arranged around the first fixed seat 2, and a slider 41 is arranged on the guide rail 4, and the slider 41 can move freely along the guide rail 4; a vertical mounting platform 5 is arranged on the slider 41, and the top of the mounting platform 5 extends to the surface of the first fixed seat 2, and an ultrasonic detector 6 is arranged on the top of the mounting platform 5, and the ultrasonic direction emitted by the ultrasonic detector 6 is along the radial direction of the guide rail 4 and passes above the center position of the first fixed seat 2. The ultrasonic detector 6 can directly detect the width of the welding gap. By adjusting the distance between the valve body and the valve cover, when the detection gap width of the ultrasonic detector 6 is exactly equal to the preset welding gap width, the gap size is accurately adjusted. This avoids the errors existing in the process of manual naked eye observation or surveying and mapping adjustment, and improves the welding quality.

[0039] like Figure 3 As shown, in the specific scheme, the base 1 is a horizontal plate-shaped structure, and the first fixing seat 2 includes a mounting ring 21, which is a vertically arranged circular ring-shaped structure. Four hydraulic telescopic rods 11 are arranged at the bottom of the mounting ring 21 at equal intervals, so as to drive the mounting ring 21 to move in the vertical direction. A connecting piece 22 is coaxially arranged at the center of the mounting ring 21 to fix the valve body of the four-way valve. Figure 4 As shown, as a preference, the connecting member 22 includes a vertically arranged limiting cylinder 221, the limiting cylinder 221 is coaxially arranged at the center of the mounting ring 21, a plurality of adjusting plates 222 are arranged circumferentially inside the limiting cylinder 221, the adjusting plates 222 include a vertical section and an inclined section, one end of the inclined section is rotationally connected to the inside of the limiting cylinder 221, and the other end is rotationally connected to the vertical section, a plurality of springs 223 are arranged on one side of the vertical section close to the inner wall of the limiting cylinder 221, and the springs 223 are evenly arranged at equal intervals in the vertical direction. When one of the valve ports of the valve body is inserted into the limiting cylinder 221, it first abuts against the inclined section, then slides downward along the inclined section, and presses the vertical section toward the inner wall of the limiting cylinder 221, and finally the valve body is fixed by the elastic force applied by the spring 223 to the vertical section, so that it cannot move in the horizontal plane.

[0040] Two horizontal clamping plates 23 are correspondingly arranged on both sides of the upper position of the connecting member 22. The clamping plates 23 are arranged symmetrically along the axis relative to the central axis of the mounting ring 21, and the clamping plates 23 can move relatively synchronously, so as to adjust the spacing between the clamping plates 23. In this embodiment, a third telescopic rod 24 arranged horizontally is used to control the movement of the clamping plates 23. When a valve port of the valve body is inserted into the interior of the limiting cylinder 221, the valve body cannot move horizontally. At this time, the valve body is clamped by the clamping plates 23 so that the valve body cannot rotate, and the clamping and fixing of the valve body is completed.

[0041] In a further solution, two slide rails 25 are further provided at the bottom of the mounting ring 21. The slide rails 25 are arranged parallel to the clamping plate 23. A plurality of horizontal support rods 26 are installed between the slide rails 25. The support rods 26 are perpendicular to the slide rails 25 and are movably arranged with the slide rails 25, so that the support rods 26 can move horizontally along the slide rails 25. Since the four-way valve of the present invention has three parallel valve ports on a single side, if one of the valve ports on both sides needs to be welded, after only inserting it into the limit cylinder 221, the center of gravity of the other side is obviously asymmetric and prone to deflection. Therefore, the position of the support rod 26 can be adjusted by the slide rail 25 so that it is just stuck in the position between the adjacent valve ports, supporting the valve as a whole to prevent it from tilting and affecting the clamping effect.

[0042] The traditional valve body is a straight tube or T-tube structure, which can be fixed by a placement groove with a shape adaptation. However, for this four-way valve, because it is different from the structure of the conventional valve body, it is difficult to manufacture a placement groove with a shape adaptation, which can simultaneously fix the valve ports on both sides of the four-way valve upwards, and can also be aligned with the valve cover above at the same time. In addition, the method of fixing the valve body by the placement groove can only be used for valve bodies of a single size, and cannot be universal for valve bodies of different sizes, resulting in a separate clamp for each size and model of valve, which is more cumbersome when used and also brings higher equipment costs. The present invention, through the structure of the first fixed seat 2, can achieve effective fixation for a single valve port or three parallel valve ports on both sides of the four-way valve. At the same time, through the cooperation of the internal spring 223 of the clamp and the clamping plate 23, valve bodies of different sizes can be clamped, which has a wider range of applications.

[0043] like Figure 5 As shown, in an embodiment of the present invention, the bracket includes a mounting frame 12 horizontally arranged above the first fixing seat 2, the second fixing seat 3 is arranged in the middle of the mounting frame 12, and a plurality of first telescopic rods 13 are arranged on the edge of the mounting frame 12. The first telescopic rods 13 control the movement of the mounting frame 12 in the vertical direction, thereby adjusting the width of the gap between the valve body and the valve cover.

[0044] Furthermore, a transfer sleeve 7 is provided in the installation frame 12, and the transfer sleeve 7 is arranged. Two parallel adjustment rods 121 are also provided on the installation frame 12, and the adjustment rods 121 horizontally penetrate the side wall of the transfer sleeve 7, one of the adjustment rods 121 is slidably connected with the transfer sleeve 7, and the other adjustment rod 121 is screw-connected with the transfer sleeve 7 through a thread, and when the adjustment rod 121 rotates, the transfer sleeve 7 is driven to move along the direction of the adjustment rod 121. Because there are three parallel valve ports on one side of the four-way valve clamped by the present invention, when the valve body and valve cover corresponding to the three valve ports need to be welded, the movement of the transfer sleeve 7 can be controlled by the adjustment rod 121, so that the second fixed seat 3 moves to the top of the corresponding valve port, and then moves in the vertical direction.

[0045] like Figure 6 As shown, in the specific scheme, six second telescopic rods 31 are arranged around the interior of the fixed sleeve. It should be noted that the first telescopic rod 13, the second telescopic rod 31 and the third telescopic rod 24 in this embodiment are all electric telescopic structures. Because their principles belong to the prior art, they are not described in detail in this embodiment. The second telescopic rod 31 is arranged along the radial direction of the fixed sleeve. One end of the second telescopic rod 31 is connected to the inner wall of the fixed sleeve, and the other end is provided with a pressing plate 32. By simultaneously extending and retracting the second telescopic rod 31, the pressing plate 32 is controlled to abut against the outer side of the valve cover, so that the valve cover can be fixed inside the fixed sleeve. The pressing plate 32 can be made of flexible silicone material, so that it has an excellent friction coefficient and good flexibility, and can be fixed tightly on the surface of the valve cover.

[0046] The ultrasonic detector 6 in the present invention is set on the slider 41 through the mounting platform 5, and moves along the guide rail 4 following the slider 41. During the movement, because the connecting line between the sliders 41 is always radial, the ultrasonic wave emitted by the ultrasonic detector 6 is always toward the gap between the welding surface of the valve body and the valve cover. In this way, the welding surface can be detected through a 360° rotation, avoiding the problem that some gaps are too small due to the uneven welding surface, making it difficult for flux and welding wire to enter, thereby affecting the welding quality.

[0047] Corresponding to the above structure, the second fixed seat 3 in this embodiment includes a vertically arranged fixed sleeve, which is a hollow cylindrical structure. The fixed sleeve is rotatably installed inside the adapter sleeve 7 and can only rotate, and cannot move vertically along the axial direction. One end face of the fixed sleeve extends out of the adapter sleeve 7, and a driven gear is arranged around the outer side of the end face. A motor 71 is installed on the corresponding end face of the adapter sleeve 7. The output end of the motor 71 is provided with a driving gear, and the driving gear meshes with the driven gear to control the rotation of the driven gear and the fixed sleeve. In this way, the valve cover can be axially rotated relative to the valve body to adjust the relative angle of the welding surface. When the problem of too small welding gap caused by uneven welding surface occurs, it can be adjusted by rotating the valve cover so that the protruding points and concave points of the valve body and the valve cover on the welding surface are matched, so that the width of the gap on the welding surface is more uniform, and the welding quality is correspondingly improved.

[0048] The four-way valve cover welding method using the above-mentioned clamp in the embodiment of the present invention comprises the following steps:

[0049] (1) Install the valve body on the first fixing seat 2, and the valve cover on the second fixing seat 3. Adjust the horizontal position of the second fixing seat 3 so that the valve body and the valve cover correspond to each other up and down. Then drive the second fixing seat 3 to move downward so that the welding surfaces of the valve cover and the valve body are in close contact with each other.

[0050] (2) Turn on the ultrasonic detector 6, and then slowly adjust the second fixing seat 3 to move upward until the gap width detected by the ultrasonic detector 6 is exactly the same as the required welding gap width;

[0051] (3) The ultrasonic detector 6 is rotated 360° around the first fixing seat 2 as a whole. If the gap width detected by the ultrasonic detector 6 meets the welding standard, the welding process can be started; if the ultrasonic detector 6 cannot detect the gap within a certain range of arc or the gap is much smaller than the welding gap width, the second fixing seat 3 is rotated to adjust the angle of the contact surface between the valve body and the valve cover. The ultrasonic detector 6 is rotated 360° for detection every time a certain angle is adjusted until the gap width detection meets the standard.

[0052] It should be noted that the gap detection standard can be determined artificially according to the welding accuracy requirements. For example, when the ultrasonic detector 6 rotates 360°, the angle range occupied by the gap width detected is not equal to the target welding gap width is not greater than 10°.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A four-way valve cover welding fixture, characterized in that: It comprises a base, a first fixing base, a second fixing base and a detection device arranged on the base; The first fixing seat is movably arranged on the surface of the base, and is used to clamp the valve body of the four-way valve. A driving device is arranged at the bottom of the first fixing seat to drive it to move in the vertical direction; The second fixing seat is mounted above the first fixing seat through a bracket, and the second fixing seat is used to clamp the valve cover of the four-way valve. The bracket is a movable structure, which can drive the second fixing seat to move in the horizontal and vertical directions respectively; The detection device is movably connected to the base so that it can rotate around the first fixed seat. The height of the detection device corresponds to the top surface position of the first fixed seat, so that the detection device can completely cover the annular side surface above the first fixed device through the rotation process.

2. A four-way valve cover welding fixture as claimed in claim 1, characterized in that: The first fixing seat includes a mounting ring, which is a vertically arranged circular ring structure. A connecting piece is coaxially arranged at the center position of the mounting ring to fix the valve body of the four-way valve. Two horizontal clamping plates are correspondingly arranged on both sides above the connecting piece. The clamping plates are axially symmetrically arranged relative to the central axis of the mounting ring, and the clamping plates can move relatively and synchronously to adjust the spacing between the clamping plates.

3. A four-way valve cover welding fixture as claimed in claim 2, characterized in that: Two slide rails are also provided at the bottom of the mounting ring. The slide rails are arranged parallel to the clamping plate. A plurality of horizontal support rods are installed between the slide rails. The support rods are perpendicular to the slide rails and are movably arranged with the slide rails so that the support rods can move horizontally along the slide rails.

4. A four-way valve cover welding fixture as claimed in claim 2, characterized in that: The connecting member includes a vertically arranged limit cylinder, which is coaxially arranged at the center position of the mounting ring. A plurality of adjustment plates are circumferentially arranged inside the limit cylinder, and the adjustment plates include a vertical section and an inclined section. One end of the inclined section is rotatably connected to the inside of the limit cylinder, and the other end is rotatably connected to the vertical section. A plurality of springs are arranged on one side of the vertical section close to the inner wall of the limit cylinder, and the springs are evenly arranged at equal intervals along the vertical direction.

5. A four-way valve cover welding fixture as claimed in claim 1, characterized in that: The bracket includes a mounting frame horizontally arranged above a first fixing seat, the second fixing seat is arranged in the middle of the mounting frame, and a plurality of first telescopic rods are arranged on the edge of the mounting frame, and the first telescopic rods control the mounting frame to move in a vertical direction.

6. A four-way valve cover welding fixture as claimed in claim 5, characterized in that: A transfer sleeve is provided in the installation frame, and the transfer sleeve is arranged. Two parallel adjustment rods are also provided on the installation frame, and the adjustment rods horizontally penetrate the side wall of the transfer sleeve. One of the adjustment rods is slidingly connected to the transfer sleeve, and the other adjustment rod is screw-connected to the transfer sleeve through a thread. When the adjustment rod rotates, the transfer sleeve is driven to move along the direction of the adjustment rod.

7. A four-way valve cover welding fixture as claimed in claim 6, characterized in that: The second fixing seat includes a vertically arranged fixing sleeve, which is a hollow cylindrical structure. The fixing sleeve is rotatably installed inside the adapter sleeve and can only rotate but cannot move vertically along the axial direction. A plurality of second telescopic rods are arranged around the interior of the fixing sleeve. The second telescopic rods are arranged along the radial direction of the fixing sleeve. One end of the second telescopic rod is connected to the inner wall of the fixing sleeve, and the other end is provided with a pressing sheet.

8. A four-way valve cover welding fixture as claimed in claim 7, characterized in that: One end face of the fixed sleeve extends out of the adapter sleeve, and a driven gear is arranged around the outer side of the end face. A motor is installed on the corresponding end face of the adapter sleeve. A driving gear is arranged at the output end of the motor. The driving gear meshes with the driven gear to control the rotation of the driven gear and the fixed sleeve.

9. A four-way valve cover welding fixture as claimed in claim 1, characterized in that: The detection device includes a horizontal guide rail arranged on the base, the guide rail is an annular structure arranged around the first fixed seat, and a slider is provided on the guide rail, and the slider can move freely along the guide rail; a vertical mounting platform is provided on the slider, and the top of the mounting platform extends to the surface of the first fixed seat, and an ultrasonic detector is provided on the top of the mounting platform. The detection direction of the ultrasonic detector is along the radial direction of the guide rail and passes above the center position of the first fixed seat.

10. A method for welding a four-way valve cover using the welding fixture according to claim 1, characterized in that: The steps include: S1. Install the valve body on the first fixing seat, install the valve cover on the second fixing seat, adjust the horizontal position of the second fixing seat so that the valve body and the valve cover correspond to each other, and then drive the second fixing seat to move downward so that the welding surfaces of the valve cover and the valve body are in close contact with each other; S2, turn on the ultrasonic detector, and then slowly adjust the second fixing seat to move upward until the gap width detected by the ultrasonic detector is exactly the same as the required welding gap width; S3. Rotate the ultrasonic detector 360° around the first fixed seat as a whole. If the gap width detected by the ultrasonic detector meets the welding standard, the welding process can be started. If the ultrasonic detector cannot detect the gap within a certain range of arc or the gap is much smaller than the welding gap width, rotate the second fixed seat, adjust the angle of the contact surface between the valve body and the valve cover, and perform a 360° rotation test of the ultrasonic detector every time a certain angle is adjusted until the gap width detection meets the standard.

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