Light vehicle door cover line robot welding clamp structure, assembly process and use method

Abstract

The invention provides a light vehicle door cover line robot welding clamp structure, an assembly process and a use method, and relates to the technical field of automobile part machining, the light vehicle door cover line robot welding clamp structure comprises an upper U-shaped supporting frame, side fixing frames, lower fixing frames and a lower supporting base, the side fixing frames are arranged on the two sides of the upper U-shaped supporting frame at intervals in an array mode, and the lower fixing frames are arranged on the lower supporting base; lower fixing frames are arranged on the two sides of an upper U-shaped supporting frame at intervals in an array mode, side connecting rotating shafts are fixedly arranged on the two sides of the upper U-shaped supporting frame, a worm wheel is fixed to the tail end of the side connecting rotating shaft on one side of the upper U-shaped supporting frame, and lower connecting sliding frames are fixed to the two sides of the top of the upper U-shaped supporting frame at intervals in an array mode. The upper U-shaped supporting frame rotates by 180 degrees along with the side connecting rotating shaft and the worm gear, the automobile door outer cover plate can be assembled and converted from the upper automobile door inner plate and the lower automobile door inner plate, and the problems that the machining transfer procedure is added due to secondary movement of the automobile door inner plate and the automobile door outer cover plate and fixture fixing operation, and the machining time interval is increased are solved.

Description

Technical Field

[0001] The invention relates to the technical field of automobile parts processing, and in particular to a robot welding fixture structure for a door cover line of a light vehicle, an assembly process and a use method thereof. Background Art

[0002] Light vehicles refer to motor vehicles with a relatively light total weight and designed to transport a small number of passengers or cargo. The vehicle's frame, door cover, etc. are produced by the frame production line and door cover production line, and finally assembled in the final assembly workshop. The door cover production line is a production line that assembles and welds door inner panels and door outer cover panels by robots.

[0003] The inner door panel is first fixed by a welding fixture and then welded. Then, the inner door panel is welded and transferred to another fixture. The inner door panel and the outer door cover panel are assembled and fixed. Then, the inner door panel and the outer door cover panel are welded. The welding of the inner door panel and the outer door cover panel also requires the replacement of the fixture. The secondary movement and fixture fixing operations of the inner door panel and the outer door cover panel increase the transfer process of the processing. The setting of the transfer time increases the time interval of the processing. Summary of the invention

[0004] The disclosed embodiments relate to a robot welding fixture structure, assembly process and use method for a door cover line of a light vehicle. The upper U-shaped support frame rotates 180 degrees along with the side connecting shaft and the worm gear, so that the door outer cover panel can be assembled from the upper and lower door inner panels, and subsequent conversion operations can be performed, eliminating the need to transfer the door inner panel to another fixture for fixation after welding, thereby reducing the transfer process during processing, reducing the processing time interval, and improving the efficiency of the door welding processing.

[0005] The present invention provides a robot welding fixture structure for a door cover line of a light vehicle, specifically comprising: an upper U-shaped support frame, a side fixing frame, a lower fixing frame and a lower supporting base, wherein side fixing frames are arranged in an array at intervals on both sides of the upper U-shaped support frame, lower fixing frames are arranged in an array at intervals on both sides of the upper U-shaped support frame, lower supporting bases are arranged on both sides of the upper U-shaped support frame, side connecting rotating shafts are fixedly arranged on both sides of the upper U-shaped support frame, a worm gear is fixed to the tail end of the side connecting rotating shaft on one side of the upper U-shaped support frame, lower connecting slides are fixed to both sides of the top of the upper U-shaped support frame at intervals, an upper connecting slide is vertically slidably provided on the upper part of the lower connecting slide, a side screw is rotatably connected to one side of the upper connecting slide, the side screw rotates, and the side screw moves axially along the thread of the lower connecting slide, and the upper connecting slide and the side screw move synchronously to adjust the height.

[0006] In at least some embodiments, the lower end of the side screw is threadedly connected to the lower connecting slide, the top of the upper connecting slide is fixedly connected to the side fixing frame, the side connecting shaft is rotatably connected to the upper part of the lower supporting base, and the upper U-shaped support frame rotates one hundred and eighty degrees along with the side connecting shaft.

[0007] In at least some embodiments, the top of the side fixed frame is rotatably connected to the middle of the upper fixed rotating frame, the head end of the upper fixed rotating frame is slidably connected to the spherical block on the top of the upper fixed pressure block, a middle support spring is provided between the upper fixed rotating frame and the upper fixed pressure block, the middle support spring supports the upper fixed rotating frame and the upper fixed pressure block to maintain axial alignment, the tail end of the upper fixed rotating frame is rotatably connected to the rear connecting rod shaft, and the tail end of the rear connecting rod is rotatably connected to the telescopic rod shaft of the first telescopic cylinder.

[0008] In at least some embodiments, the first telescopic cylinder is fixedly connected to the upper connecting slide, the upper fixed pressure block is located above the lower fixing frame, the head end of the side fixing frame is horizontally slidably connected to the lower fixing frame, a side sliding groove is provided on the side of the side fixing frame, a threaded column slides inside the side sliding groove, a side fixing nut is screwed on the upper part of the threaded column, and the lower end of the threaded column is fixedly connected to the upper connecting slide.

[0009] In at least some embodiments, a side limiting stud is fixedly provided on the top rear side of the lower fixing frame, a middle portion of the side limiting stud and a middle portion of the upper limiting block are penetrated by a slide groove, an upper fixing nut is screwed on the top of the side limiting stud, a middle connecting frame is fixed by side bolts of the lower fixing frame, and the middle connecting frame is vertically slidably connected to the telescopic rod of the second telescopic cylinder.

[0010] In at least some embodiments, the second telescopic cylinder is fixedly connected to the side fixing frame, the lower fixing frame is bolted to both sides of the middle connecting frame, the lower fixing frame moves horizontally synchronously, and the second telescopic cylinder pulls the lower fixing frame to move toward both sides.

[0011] In at least some embodiments, the upper motor of the lower support base is driven to rotate with a worm gear, and one side of the lower support base is driven to rotate with a lifting screw in the vertical direction by a motor. The lifting screw is threadedly connected to the middle bracket, and the middle bracket moves downward along the lifting screw to make room for the upper U-shaped support frame to rotate.

[0012] In at least some embodiments, the worm and the worm wheel are meshingly connected, and the worm starts to mesh and drives the worm wheel to rotate, and the worm wheel and the side connecting shaft rotate synchronously, the upper U-shaped support frame rotates one hundred and eighty degrees along with the side connecting shaft, the middle bracket and the lower support base are vertically slidably connected, and the tail of the middle bracket is located in the middle position of the side fixing frame.

[0013] The invention discloses an assembly process and a use method of a robot welding fixture structure for a light vehicle door cover line, comprising the following steps:

[0014] The upper U-shaped support frame is rotated to a horizontal direction, and the door inner panel is assembled and placed on top of the lower support base and the middle support frame;

[0015] The first telescopic cylinder extends to push the upper fixed rotating frame to rotate, and the upper fixed pressing block at the head end of the upper fixed rotating frame moves downward to press the door inner panel on the top of the lower supporting base, and the robot welds the fixed door inner panel;

[0016] After the middle bracket moves down to the lowest position, the upper U-shaped support frame rotates 180 degrees along with the side connecting shaft and the worm gear, and the second telescopic cylinder shortens and pulls the lower fixed frame to move outward, placing the door outer cover panel above the door inner panel;

[0017] The upper fixed pressing block at the front end of the upper fixed rotating frame moves downward, the lower fixed frame moves to above the door outer cover panel, the upper fixed pressing block moves upward to clamp the door outer cover panel and the door inner panel, and the robot welds the fixed door outer cover panel and the door inner panel.

[0018] The present invention provides a light vehicle door cover line robot welding fixture structure and assembly process and use method, which has the following features:

[0019] Beneficial effects:

[0020] The upper U-shaped support frame rotates 180 degrees with the side connecting shaft and the worm gear, so that the door outer cover panel can be assembled from the upper and lower door inner panels for subsequent conversion operations, eliminating the need to transfer the door inner panel to another fixture for fixation after welding, reducing the transfer process during processing, reducing the processing time interval, and improving the efficiency of door welding processing.

[0021] The side fixing frame adjusts its height as the upper connecting slide moves vertically to adapt to the height changes of door cover panels of different models. The side fixing frame moves horizontally through the side slide groove to adapt to the width changes of door cover panels of different models, thereby improving compatibility with door cover panels of different models.

[0022] The second telescopic cylinder pulls the lower fixed frame to move toward both sides, which is convenient for assembling and placing the door outer cover panel. The sliding between the upper fixed rotating frame and the upper fixed pressing block adapts to the inclined surface of the door cover panel, thereby improving the firmness during clamping and fixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings of the embodiment are briefly introduced below.

[0024] The drawings described below are only related to some embodiments of the present invention, but are not intended to limit the present invention.

[0025] In the attached picture:

[0026] Figure 1A schematic diagram showing the overall structure of the present application;

[0027] Figure 2 A schematic structural diagram of a side fixing frame of the present application is shown;

[0028] Figure 3 A schematic diagram showing a side fixing frame structure of the present application is shown;

[0029] Figure 4 A schematic diagram of the structure of the upper U-shaped support frame of the present application is shown;

[0030] Figure 5 A schematic diagram of the structure of the lower fixing frame of the present application is shown;

[0031] Figure 6 A schematic structural diagram of the lower support base of the present application is shown;

[0032] Figure 7 The schematic diagram of the structure of the side slide groove of the present application is shown;

[0033] Figure 8 A schematic diagram showing the split state of the present application;

[0034] Reference numerals list

[0035] 1. Upper U-shaped support frame; 101. Side connecting shaft; 102. Worm gear; 103. Lower connecting slide; 104. Upper connecting slide; 105. Side screw;

[0036] 2. Side fixing frame; 201. Upper fixing rotating frame; 202. Upper fixing pressing block; 203. Middle supporting spring; 204. Rear connecting rod; 205. First telescopic cylinder; 206. Side sliding groove; 207. Threaded column; 208. Side fixing nut;

[0037] 3. Lower fixing frame; 301. Side limiting stud; 302. Upper limit block; 303. Upper fixing nut; 304. Middle connecting frame; 305. Second telescopic cylinder;

[0038] 4. Lower supporting base; 401. Worm; 402. Lifting screw; 403. Middle bracket. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1: Please refer to Figures 1 to 8 :

[0041] The present invention proposes a robot welding fixture structure for a light vehicle door cover line, comprising: an upper U-shaped support frame 1, a side fixing frame 2, a lower fixing frame 3 and a lower supporting base 4, both sides of the upper U-shaped support frame 1 are fixedly provided with side connecting shafts 101, a worm gear 102 is fixed to the tail end of the side connecting shaft 101 on one side of the upper U-shaped support frame 1, lower connecting slides 103 are fixed in an array at intervals on both sides of the top of the upper U-shaped support frame 1, an upper connecting slide 104 is vertically slidably provided on the upper part of the lower connecting slide 103, a side screw 105 is rotatably connected to one side of the upper connecting slide 104, the side screw 105 rotates, and the side screw 105 moves axially along the thread of the lower connecting slide 103, the upper connecting slide 104 and the side screw 105 move synchronously to adjust the height, and the side fixing frame 2 moves vertically with the upper connecting slide 104 to adjust the height. Adjust the height to adapt to the height changes of door cover panels of different models. Side fixing frames 2 are arranged in an array at intervals on both sides of the upper U-shaped support frame 1. The top of the side fixing frame 2 is rotatably connected to the middle of the upper fixed rotating frame 201. The head end of the upper fixed rotating frame 201 is slidably connected to the top spherical block of the upper fixed pressure block 202. A middle support spring 203 is arranged between the upper fixed rotating frame 201 and the upper fixed pressure block 202. The middle support spring 203 supports the upper fixed rotating frame 201 and the upper fixed pressure block 202 to maintain axial alignment. The tail end of the upper fixed rotating frame 201 is rotatably connected to the rotating shaft of the rear connecting rod 204. The tail end of the rear connecting rod 204 is rotatably connected to the rotating shaft of the telescopic rod of the first telescopic cylinder 205. The first telescopic cylinder 205 is fixedly connected to the upper connecting slide 104, and the upper fixed pressure block 202 is located above the lower fixed frame 3.

[0042] The head end of the side fixing frame 2 is horizontally slidably connected to the lower fixing frame 3, a side sliding groove 206 is opened on the side of the side fixing frame 2, a threaded column 207 is slidably provided inside the side sliding groove 206, a side fixing nut 208 is screwed on the upper part of the threaded column 207, and the lower end of the threaded column 207 is fixedly connected to the upper connecting slide 104, and the lower fixing frames 3 are arranged in an array at intervals on both sides of the upper U-shaped support frame 1, and a side limiting stud 301 is fixedly arranged on the top rear side of the lower fixing frame 3, and the middle part of the side limiting stud 301 and the middle sliding groove of the upper limit block 302 pass through, and the top of the side limiting stud 301 An upper fixing nut 303 is screwed, and a middle connecting frame 304 is fixed to the side bolts of the lower fixing frame 3. The middle connecting frame 304 is vertically slidably connected to the telescopic rod of the second telescopic cylinder 305. Lower supporting bases 4 are arranged on both sides of the upper U-shaped supporting frame 1. A worm 401 is arranged on the upper part of the lower supporting base 4 for driving rotation by a motor. A lifting screw 402 is arranged on one side of the lower supporting base 4 for driving rotation by a motor in a vertical direction. The lifting screw 402 and the middle bracket 403 are screwed. The middle bracket 403 moves downward along the lifting screw 402 to make room for the upper U-shaped supporting frame 1 to rotate.

[0043] In the disclosed embodiment, the lower end of the side screw rod 105 is screwed to the lower connecting slide 103, the top of the upper connecting slide 104 is fixedly connected to the side fixing frame 2, the side connecting shaft 101 is rotatably connected to the upper part of the lower supporting base 4, the upper U-shaped supporting frame 1 rotates one hundred and eighty degrees along with the side connecting shaft 101, the middle bracket 403 moves up and fits with the door inner panel for auxiliary support in the center, and then the robot performs subsequent mobile conversion fixture operations on the door outer cover panel and the door inner panel, eliminating the situation where the door inner panel is transferred to another fixture for fixation after welding, reducing the transfer process during the processing of the door outer cover panel and the door inner panel, and reducing the time interval for processing the door outer cover panel and the door inner panel.

[0044] In the disclosed embodiment, the second telescopic cylinder 305 is fixedly connected to the side fixing frame 2, and the lower fixing frames 3 are bolted to both sides of the middle connecting frame 304. The lower fixing frames 3 move horizontally synchronously, and the second telescopic cylinder 305 pulls the lower fixing frames 3 to move toward both sides. The lower fixing frames 3 are no longer above the inner door panel, and the lower fixing frames 3 will not hinder the downward movement of the door outer cover panel and the splicing of the door inner panel, which facilitates the assembly work of the door outer cover panel hanging down.

[0045] In the disclosed embodiment, the worm 401 and the worm wheel 102 are meshingly connected. The worm 401 starts to mesh and drives the worm wheel 102 to rotate. The worm wheel 102 and the side connecting shaft 101 rotate synchronously. The upper U-shaped support frame 1 rotates one hundred and eighty degrees along with the side connecting shaft 101. The middle bracket 403 and the lower support base 4 are vertically slidably connected. The tail of the middle bracket 403 is in the middle position of the side fixing frame 2. The middle bracket 403 moves up and fits the inner panel of the door to provide auxiliary support for the center.

[0046] The invention discloses an assembly process and a use method of a robot welding fixture structure for a light vehicle door cover line, comprising the following steps:

[0047] The upper U-shaped support frame 1 is rotated to the horizontal direction, and the door inner panel is assembled and placed on top of the lower support base 4 and the middle support 403;

[0048] The first telescopic cylinder 205 extends to push the upper fixed rotating frame 201 to rotate, and the upper fixed pressing block 202 at the front end of the upper fixed rotating frame 201 moves downward to press the door inner panel on the top of the lower supporting base 4, and the robot welds the fixed door inner panel;

[0049] After the middle bracket 403 moves down to the lowest position, the upper U-shaped support frame 1 rotates 180 degrees along with the side connecting shaft 101 and the worm gear 102, and the second telescopic cylinder 305 shortens and pulls the lower fixing frame 3 to move outward, placing the door outer cover panel above the door inner panel;

[0050] The upper fixed pressing block 202 at the front end of the upper fixed rotating frame 201 moves downward, the lower fixed frame 3 moves to above the door outer cover panel, the upper fixed pressing block 202 moves upward to clamp the door outer cover panel and the door inner panel, and the robot welds the fixed door outer cover panel and the door inner panel.

[0051] Embodiment 2, on the basis of embodiment 1, the bottom of the lower supporting base 4 is fixedly arranged on both sides of a circular rotating frame, and a group of lower supporting base 4, side fixing frame 2, lower fixing frame 3, and upper U-shaped supporting frame 1 are arranged on both sides of the circular rotating frame, and the circular rotating frame rotates back and forth to switch the lower supporting base 4, side fixing frame 2, lower fixing frame 3, and upper U-shaped supporting frame 1 on both sides, and the manipulators on both sides take turns to perform the welding of the inner door panel, the outer door cover panel and the inner door panel.

[0052] The working principle of the first embodiment is as follows: the first telescopic cylinder 205 is shortened, and the first telescopic cylinder 205 pulls the upper fixed rotating frame 201 to rotate through the rear connecting rod 204, and the upper fixed rotating frame 201 rotates around the rotating connection between the middle and the side fixed frame 2, and the head end of the upper fixed rotating frame 201 and the upper fixed pressing block 202 move upward, and the upper fixed pressing block 202 moves away from and is no longer above the lower fixed frame 3, and the inner door panel is placed on the lower fixed frame 3, and the upper limit block 302 and the edge of the inner door panel are fitted and limited, and the rectangular slide groove of the upper limit block 302 slides and adjusts along the side limit stud 301 to adjust the edge of the door panel. During the positioning operation, the upper fixing nut 303 moves downward along the thread of the side limiting stud 301 to clamp the upper limiting block 302 to fix the position, the first telescopic cylinder 205 extends, the head end of the upper fixing rotating frame 201 and the upper fixing pressing block 202 move downward, and the upper fixing pressing block 202 presses down and fixes the door inner panel from above, and the spherical sliding structure between the upper fixing rotating frame 201 and the upper fixing pressing block 202 adjusts the tilting direction and angle in multiple directions, and the upper fixing pressing block 202 tilts to adapt to the inclined surface of the door cover panel to improve the firmness during clamping and fixing, and the robot performs the welding process after the door inner panel is fixed;

[0053] After the door inner panel is welded, the middle bracket 403 moves down along the lifting screw 402 to make room for the upper U-shaped support frame 1 to rotate, and the worm 401 starts to engage and drives the worm wheel 102 to rotate, and the worm wheel 102 and the side connecting shaft 101 rotate synchronously, and the upper U-shaped support frame 1 rotates 180 degrees along with the side connecting shaft 101, and the second telescopic cylinder 305 pulls the lower fixed frame 3 to move to both sides, and the lower fixed frame 3 is no longer above the door inner panel, and the lower fixed frame 3 will not hinder the downward movement of the door outer cover panel and the splicing of the door inner panel, so as to facilitate the assembly and placement of the door outer cover panel. After the door outer cover panel and the door inner panel are placed in place, the first telescopic cylinder 205 is shortened, and the upper fixed rotating frame 201 at the head end at the bottom after flipping is turned over. The fixed pressure block 202 will move downward at this time, and the upper fixed pressure block 202 and the door outer cover plate and the door inner panel will move downward synchronously to make room for the lower fixing frame 3 to reset. After the lower fixing frame 3 moves to the top of the door outer cover plate, the first telescopic cylinder 205 extends, and the upper fixed pressure block 202 moves upward to clamp the door outer cover plate and the door inner panel. The middle bracket 403 moves upward and fits the door inner panel for auxiliary support in the center. Then the robot performs subsequent welding operations on the door outer cover plate and the door inner panel, eliminating the need to transfer the door inner panel to another fixture for fixing after welding, reducing the transfer process during the processing of the door outer cover plate and the door inner panel, reducing the time interval for processing the door outer cover plate and the door inner panel, and improving the efficiency of the door welding process.

[0054] The side screw 105 rotates, and the side screw 105 moves axially along the thread of the lower connecting slide 103. The upper connecting slide 104 and the side screw 105 move synchronously to adjust the height. The side fixing frame 2 moves vertically with the upper connecting slide 104 to adjust the height to adapt to the height changes of door cover panels of different models. The side fixing frame 2 moves horizontally along the threaded column 207 through the side slide groove 206, and the side fixing nut 208 moves downward to clamp the side slide groove 206 to fix the position of the side fixing frame 2. The lower fixing frame 3 changes its position with the side fixing frame 2, and the middle connecting frame 304 needs to be disassembled and replaced with the corresponding length to adapt to the width changes of door cover panels of different models and improve the compatibility with door cover panels of different models.

[0055] In this article, there are a few points to note:

[0056] 1. The drawings of the embodiments of the present disclosure only involve structures related to the embodiments of the present disclosure, and other structures may refer to general designs.

[0057] 2. In the absence of conflict, the embodiments of the present disclosure and the features therein may be combined with each other to obtain new embodiments.

[0058] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A robot welding fixture structure for a light vehicle door cover line, comprising: An upper U-shaped support frame (1), a side fixing frame (2), a lower fixing frame (3) and a lower supporting base (4); characterized in that side fixing frames (2) are arranged in an array at intervals on both sides of the upper U-shaped support frame (1), lower fixing frames (3) are arranged in an array at intervals on both sides of the upper U-shaped support frame (1), lower supporting bases (4) are arranged on both sides of the upper U-shaped support frame (1), side connecting shafts (101) are fixedly arranged on both sides of the upper U-shaped support frame (1), a worm gear (102) is fixedly mounted at the tail end of the side connecting shaft (101) on one side of the upper U-shaped support frame (1), lower connecting slides (103) are fixed in an array at intervals on both sides of the top of the upper U-shaped support frame (1), an upper connecting slide (104) is vertically slidably arranged on the upper part of the lower connecting slide (103), and a side screw (105) is rotatably connected to one side of the upper connecting slide (104).

2. A light vehicle door cover line robot welding fixture structure according to claim 1, characterized in that: The lower end of the side screw rod (105) is screwed to the lower connecting slide (103), the top of the upper connecting slide (104) is fixedly connected to the side fixing frame (2), and the side connecting shaft (101) is rotatably connected to the upper part of the lower supporting base (4).

3. The robot welding fixture structure for door cover line of a light vehicle according to claim 1 is characterized in that: The top of the side fixed frame (2) is rotatably connected to the middle of the upper fixed rotating frame (201), the head end of the upper fixed rotating frame (201) is slidably connected to the top spherical block of the upper fixed pressing block (202), a middle support spring (203) is provided between the upper fixed rotating frame (201) and the upper fixed pressing block (202), the tail end of the upper fixed rotating frame (201) is rotatably connected to the rotating shaft of the rear connecting rod (204), and the tail end of the rear connecting rod (204) is rotatably connected to the rotating shaft of the telescopic rod of the first telescopic cylinder (205).

4. A robot welding fixture structure for a light vehicle door cover line according to claim 3, characterized in that: The first telescopic cylinder (205) is fixedly connected to the upper connecting slide (104), the upper fixed pressure block (202) is located above the lower fixing frame (3), the head end of the side fixing frame (2) is horizontally slidably connected to the lower fixing frame (3), a side sliding groove (206) is provided on the side of the side fixing frame (2), a threaded column (207) is slidably provided inside the side sliding groove (206), a side fixing nut (208) is screwed on the upper part of the threaded column (207), and the lower end of the threaded column (207) is fixedly connected to the upper connecting slide (104).

5. A robot welding fixture structure for a light vehicle door cover line according to claim 4, characterized in that: A side limiting stud (301) is fixedly arranged on the top rear side of the lower fixing frame (3), the middle part of the side limiting stud (301) and the middle part of the upper limiting block (302) are penetrated by a sliding groove, the top of the side limiting stud (301) is screwed with an upper fixing nut (303), a middle connecting frame (304) is fixed on the side of the lower fixing frame (3), and the middle connecting frame (304) is vertically slidably connected to the telescopic rod of the second telescopic cylinder (305).

6. A robot welding fixture structure for a light vehicle door cover line according to claim 5, characterized in that: The second telescopic cylinder (305) is fixedly connected to the side fixing frame (2), and both sides of the middle connecting frame (304) are fixedly connected to the lower fixing frame (3), and the lower fixing frame (3) moves synchronously and horizontally.

7. The robot welding fixture structure for door cover line of light vehicle according to claim 1 is characterized in that: The upper part of the lower support base (4) is driven and rotated by a motor and is provided with a worm (401), and one side of the lower support base (4) is driven and rotated by a motor in a vertical direction and is provided with a lifting screw (402), and the lifting screw (402) and the middle bracket (403) are screwed together.

8. The robot welding fixture structure for door cover line of light vehicle according to claim 7 is characterized in that: The worm (401) and the worm wheel (102) are meshedly connected, the middle bracket (403) and the lower support base (4) are vertically slidably connected, and the tail of the middle bracket (403) is located in the middle position of the side fixing frame (2).

9. The assembly process and use method of a robot welding fixture structure for a light vehicle door cover line according to any one of claims 1 to 8, characterized in that: The following steps are involved: 1) The upper U-shaped support frame (1) is rotated to a horizontal direction, and the door inner panel is assembled and placed on top of the lower support base (4) and the middle support (403); 2) The first telescopic cylinder (205) extends to push the upper fixed rotating frame (201) to rotate, and the upper fixed pressing block (202) at the front end of the upper fixed rotating frame (201) moves downward to press the door inner panel on the top of the lower supporting base (4), and the robot welds the fixed door inner panel; 3) After the middle bracket (403) moves down to the lowest position, the upper U-shaped support frame (1) rotates 180 degrees along with the side connecting shaft (101) and the worm gear (102), and the second telescopic cylinder (305) shortens and pulls the lower fixing frame (3) to move outward, so that the door outer cover plate is placed above the door inner plate; 4) The upper fixed pressing block (202) at the front end of the upper fixed rotating frame (201) moves downward, the lower fixed frame (3) moves above the vehicle door outer cover plate, the upper fixed pressing block (202) moves upward to clamp the vehicle door outer cover plate and the vehicle door inner plate, and the robot welds the fixed vehicle door outer cover plate and the vehicle door inner plate.

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