Polishing equipment for steam turbine blade production

Abstract

The invention relates to the technical field of polishing, in particular to steam turbine blade production polishing equipment which comprises a polishing table and a top plate, a plurality of supporting plates are fixedly connected to the top of the polishing table, the top ends of the supporting plates are fixedly connected with the bottom of the top plate, and a rotating frame and a movable box are arranged below the top plate; the top plate is provided with an autorotation unit for driving the rotating frame to autorotate; the rotating frame is provided with a translation mechanism for driving the movable box to translate, the bottom of the movable box is in contact with a mounting seat, the movable box is provided with an inclined structure for driving the mounting seat to incline, and the mounting seat is provided with a polisher for polishing; welding spots on the blade can be polished, the blade before welding does not need to be independently polished in advance, and the polishing efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polishing, and particularly to a polishing device for the production of steam turbine blades. Background Art

[0002] A steam turbine is a device that converts thermal energy into mechanical energy and is mainly used for power generation and driving machinery. During the production of steam turbine blades, a polishing machine is usually used to polish them.

[0003] It is found through retrieval of the prior art that a Chinese patent with the publication number CN222222213U discloses a polishing device for the production of steam turbine blades. Dust and solid particles are filtered through a filter screen, which helps to reduce pollution to the external environment during the filtering process. A polishing machine is used to polish the steam turbine blades.

[0004] However, it is worth considering that several blades need to be placed in the processing box for polishing in sequence. After polishing, the several blades also need to be welded together. Some solder joints will splash out during the blade assembly and welding process, resulting in the need for secondary polishing of the blades, which affects the polishing efficiency.

[0005] Therefore, in order to solve the above problems, there is a need for the emergence of a related facility that more meets the usage requirements. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a polishing device for the production of steam turbine blades to solve the problem that some solder joints will splash out during the blade assembly and welding process, resulting in the need for secondary polishing of the blades.

[0007] Based on the above purpose, the present invention provides a polishing device for the production of steam turbine blades, including a polishing table and a top plate. A plurality of support plates are fixedly connected to the top of the polishing table, and the top ends of the support plates are fixedly connected to the bottom of the top plate. A rotating frame and a movable box are arranged below the top plate. The top plate is equipped with a self-rotation unit for driving the rotating frame to rotate; the rotating frame is equipped with a translation mechanism for driving the movable box to translate. The bottom of the movable box is in contact with a mounting seat. The movable box is equipped with an inclination structure for driving the mounting seat to incline, and the mounting seat is equipped with a polisher for polishing.

[0008] Optionally, the tilting structure includes a first rotating shaft rotatably mounted on the rotating frame. A first servo motor is fixedly mounted on the rotating frame, and the output end of the first servo motor is fixedly connected to the first rotating shaft. The first rotating shaft penetrates through the movable box. A first rotating sleeve is sleeved outside the first rotating shaft. The first rotating sleeve is rotatably connected to the movable box. A connecting plate located inside the movable box is fixedly mounted on the first rotating sleeve. A first avoidance hole adapted to the connecting plate is formed on the inner wall of the movable box. The connecting plate penetrates through the first avoidance hole and is fixedly connected to the mounting seat. A damping synchronizing member is mounted on the movable box for driving the first rotating sleeve and the first rotating shaft to rotate synchronously.

[0009] Optionally, the damping synchronizing member includes a second rotating sleeve sleeved outside the first rotating shaft. The second rotating sleeve is rotatably connected to the movable box. A sliding groove is formed on the first rotating shaft. A slider is slidably disposed in the sliding groove, and the slider is fixedly connected to the inner wall of the second rotating sleeve. A first damping ring located inside the movable box is fixedly sleeved outside the second rotating sleeve. A second damping ring located inside the movable box is fixedly sleeved outside the first rotating sleeve, and the second damping ring is in contact with the first damping ring.

[0010] Optionally, the translation mechanism includes a lead screw rotatably mounted on the rotating frame. A support portion is fixedly mounted on the movable box. The lead screw penetrates through the support portion, and the connection mode between the lead screw and the support portion is a threaded connection. A second servo motor is fixedly mounted on the rotating frame, and the output end of the second servo motor is fixedly connected to the lead screw.

[0011] The beneficial effects of the present invention are as follows: The staff places several blades welded together above the polishing table. The rotating frame is driven to rotate through the rotation unit so that the polisher moves above the blade to be welded. The mounting seat is driven to tilt to a preset angle through the tilting structure, so that the polisher is in a preset angle. The blade is polished by the polisher, and the translation mechanism drives the movable box to translate, so that the polisher polishes different positions on the blade. When a single blade is polished, similarly, the rotation unit drives the rotating frame to move above the next blade, and then the next blade can be polished. Several blades welded together can be polished in sequence to complete the polishing of the solder joints on the blade, and it is not necessary to polish the blades before welding separately, improving the polishing efficiency. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only those of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0013] Figure 1 It is one of the overall structural schematic diagrams of the embodiments of the present invention; Figure 2 The second overall structural schematic diagram of the embodiment of the present invention; Figure 3 The structural schematic diagram of the rotating frame of the embodiment of the present invention; Figure 4 For the present invention Figure 3 The enlarged structural schematic diagram of area A; Figure 5 The structural schematic diagram of the bottom of the installation shell of the embodiment of the present invention; Figure 6 The structural schematic diagram of the prism of the embodiment of the present invention; Figure 7 The structural schematic diagram of the interior of the movable box of the embodiment of the present invention; Figure 8 The structural schematic diagram of the sliding sleeve of the embodiment of the present invention; Figure 9 The structural schematic diagram of the disassembly and assembly part disassembled of the embodiment of the present invention.

[0014] The markings in the figure are: 1, polishing table; 2, top plate; 3, support plate; 4, rotating frame; 5, movable box; 6, mounting seat; 7, first rotating shaft; 8, first servo motor; 9, first rotating sleeve; 10, first avoidance hole; 11, connecting plate; 12, second rotating sleeve; 13, slider; 14, chute; 15, first damping ring; 16, second damping ring; 17, lead screw; 18, support part; 19, second servo motor; 20, third servo motor; 21, prism; 22, sliding sleeve; 23, polishing wheel; 24, lifting frame; 25, first hydraulic telescopic rod; 26, fixed sleeve; 27, stop hole; 28, second avoidance hole; 29, stop block; 30, connecting block; 31, baffle; 32, movable ring; 33, fixed ring; 34, guide groove; 35, guide block; 36, compression spring; 37, installation shell; 38, fourth servo motor; 39, second rotating shaft; 40, card slot; 41, card block; 42, installation part; 43, bolt; 44, support ring; 45, connecting frame; 46, roller; 47, load-bearing seat; 48, second hydraulic telescopic rod. Specific embodiments

[0015] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0016] Embodiment 1, consisting of Figure 1 , Figure 2 , Figure 3 and Figure 4Provided, the present invention includes a polishing table 1 and a top plate 2. A plurality of support plates 3 are fixedly connected to the top of the polishing table 1, and the top ends of the support plates 3 are fixedly connected to the bottom of the top plate 2. A rotating frame 4 and a movable box 5 are provided below the top plate 2. The top plate 2 is equipped with a self-rotation unit for driving the self-rotation of the rotating frame 4; the rotating frame 4 is equipped with a translation mechanism for driving the translation of the movable box 5. The bottom of the movable box 5 is in contact with a mounting seat 6. The movable box 5 is equipped with an inclination structure for driving the inclination of the mounting seat 6. The mounting seat 6 is equipped with a polisher for polishing. The staff places a plurality of blades welded together above the polishing table 1. The self-rotation unit drives the rotation of the rotating frame 4 to move the polisher above the blade to be welded. The inclination structure drives the mounting seat 6 to incline to a preset angle, so that the polisher is at a preset angle. The polisher polishes the blade. The translation mechanism drives the translation of the movable box 5 to enable the polisher to polish different positions on the blade. When the polishing of a single blade is completed, similarly, the self-rotation unit drives the rotating frame 4 to move above the next blade, and then the next blade can be polished. A plurality of blades welded together can be polished in sequence to complete the polishing of the solder joints on the blades, and it is not necessary to polish the blades before welding separately in advance, improving the polishing efficiency.

[0017] Embodiment 2, on the basis of Embodiment 1, by Figure 3 、 Figure 4 and Figure 7Given that the inclined structure includes a first rotating shaft 7 rotatably mounted on the rotating frame 4, the rotating frame 4 is fixedly installed with a first servo motor 8, and the output end of the first servo motor 8 is fixedly connected to the first rotating shaft 7. The first rotating shaft 7 penetrates through the movable box 5. A first rotating sleeve 9 is sleeved outside the first rotating shaft 7. The first rotating sleeve 9 is rotatably connected to the movable box 5. The first rotating sleeve 9 is fixedly installed with a connecting plate 11 located inside the movable box 5. A first avoidance hole 10 adapted to the connecting plate 11 is formed on the inner wall of the movable box 5. The connecting plate 11 penetrates through the first avoidance hole 10, and the connecting plate 11 is fixedly connected to the mounting seat 6. The movable box 5 is equipped with a damping synchronizing member for driving the first rotating sleeve 9 and the first rotating shaft 7 to rotate synchronously. The damping synchronizing member includes a second rotating sleeve 12 sleeved outside the first rotating shaft 7. The second rotating sleeve 12 is rotatably connected to the movable box 5. A sliding groove 14 is formed on the first rotating shaft 7. A slider 13 is slidably arranged in the sliding groove 14, and the slider 13 is fixedly connected to the inner wall of the second rotating sleeve 12. A first damping ring 15 located inside the movable box 5 is fixedly sleeved outside the second rotating sleeve 12. A second damping ring 16 located inside the movable box 5 is fixedly sleeved outside the first rotating sleeve 9, and the second damping ring 16 is in contact with the first damping ring 15. The translation mechanism includes a lead screw 17 rotatably mounted on the rotating frame 4. The movable box 5 is fixedly installed with a supporting part 18. The lead screw 17 penetrates through the supporting part 18, and the connection mode between the lead screw 17 and the supporting part 18 is a threaded connection. The rotating frame 4 is fixedly installed with a second servo motor 19, and the output end of the second servo motor 19 is fixedly connected to the lead screw 17; The first servo motor 8 drives the first rotating shaft 7 to rotate. The first rotating shaft 7 drives the second rotating sleeve 12 and the first damping ring 15 to rotate through the slider 13. The first damping ring 15 drives the second damping ring 16 and the first rotating sleeve 9 to rotate through friction. The first rotating sleeve 9 can drive the mounting seat 6 and the polishing device to rotate through the connecting plate 11, changing the inclination angle of the polishing device. When the polishing device contacts the blade, the second damping ring 16 and the first rotating sleeve 9 are stationary relative to the movable box 5. As the first rotating shaft 7 continues to rotate, the first damping ring 15 rotates relative to the second damping ring 16, ensuring that the polishing device automatically stops when it contacts the blade. The second servo motor 19 drives the lead screw 17 to rotate. The lead screw 17 drives the supporting part 18 and the movable box 5 to move horizontally relative to the rotating frame 4. The movable box 5 drives the second rotating sleeve 12 and the slider 13 to slide relative to the sliding groove 14 and the first rotating shaft 7, so that the movable box 5 and the polishing device can move horizontally to polish different positions on the blade.

[0018] Embodiment 3, on the basis of Embodiment 1, by Figure 3 、 Figure 4 、 Figure 6 、 Figure 8 and Figure 9Given that the polisher includes a third servo motor 20 fixedly installed at the bottom of the mounting base 6, the output end of the third servo motor 20 is fixedly connected with a prism 21, a sliding sleeve 22 is slidably sleeved outside the prism 21, a polishing wheel 23 is arranged below the sliding sleeve 22, the sliding sleeve 22 is equipped with a disassembly and assembly part adapted to the polishing wheel 23, and the mounting base 6 is equipped with a telescopic part adapted to the sliding sleeve 22. The telescopic part includes a lifting frame 24 rotatably sleeved outside the sliding sleeve 22. The mounting base 6 is fixedly installed with a first hydraulic telescopic rod 25, and the telescopic end of the first hydraulic telescopic rod 25 is fixedly connected with the lifting frame 24. The disassembly and assembly part includes a fixed sleeve 26 fixedly sleeved outside the sliding sleeve 22. At least three stop holes 27 are formed in the fixed sleeve 26. A second avoidance hole 28 is formed in the bottom inner wall of the stop hole 27. A stop block 29 is arranged in the stop hole 27. The bottom and top of the stop block 29 are respectively in contact with the inner wall of the stop hole 27. The bottom of the stop block 29 is fixedly connected with a connecting block 30. The bottom of the connecting block 30 is fixedly connected with the top of the polishing wheel 23. The connecting block 30 penetrates through the second avoidance hole 28, and the stop block 29 and the connecting block 30 are respectively in contact with the outer wall of the sliding sleeve 22. The sliding sleeve 22 is equipped with a stop unit adapted to the stop block 29. The stop unit includes a baffle 31 arranged in the stop hole 27. The two sides of the stop block 29 are respectively in contact with the inner wall of the stop hole 27 and the baffle 31. A fixed ring 33 is fixedly sleeved outside the sliding sleeve 22. The top of the fixed sleeve 26 is in contact with a movable ring 32, and the top of the baffle 31 is fixedly connected with the bottom of the movable ring 32. The top of the movable ring 32 and the top of the fixed ring 33 are connected by a compression spring 36. A guide groove 34 is formed in the outer wall of the sliding sleeve 22. A guide block 35 is slidably arranged in the guide groove 34, and the guide block 35 is fixedly connected with the inner wall of the movable ring 32; The third servo motor 20 drives the prism 21 to rotate. The prism 21 drives the polishing wheel 23 to rotate synchronously through the sliding sleeve 22, and the polishing wheel 23 can polish the blade. The first hydraulic telescopic rod 25 drives the lifting frame 24 and the sliding sleeve 22 to slide relative to the prism 21, so that the polishing wheel 23 moves relative to the mounting seat 6, and the position of the polishing wheel 23 can be changed to ensure that the polishing wheel 23 polishes the blade. When the polishing wheel 23 needs to be replaced, the staff drives the movable ring 32 to move towards the fixed ring 33. The compression spring 36 is in a stretched state, and the guide block 35 slides relative to the guide groove 34. The baffle 31 moves upward relative to the stop block 29. When the baffle 31 no longer contacts the stop block 29, the baffle 31 releases the limitation on the position of the stop block 29. The staff drives the polishing wheel 23, the connecting block 30 and the stop block 29 to rotate relative to the stop hole 27 and the sliding sleeve 22, so that the bottom of the stop block 29 no longer contacts the inner wall of the bottom of the stop hole 27, and the stop hole 27 no longer limits the downward movement of the stop block 29 and the polishing wheel 23. The staff drives the polishing wheel 23 to move downward, and the polishing wheel 23 drives the stop block 29 to slide out of the second avoidance hole 28 through the connecting block 30, and the removal of the polishing wheel 23 can be completed, which is convenient to replace different specifications or damaged polishing wheels 23 according to actual needs and is convenient for later use.

[0019] Embodiment 4, on the basis of Embodiment 1, is given by Figure 1 , Figure 2 , Figure 3 and Figure 5 The self-rotation unit includes a mounting shell 37 arranged on the top plate 2. A fourth servo motor 38 is fixedly connected inside the mounting shell 37. A second rotating shaft 39 is rotatably connected to the top plate 2. The bottom end of the second rotating shaft 39 is fixedly connected to the top of the rotating frame 4. A clamping groove 40 is opened at the top end of the second rotating shaft 39. The output end of the fourth servo motor 38 is fixedly connected with a clamping block 41 located in the clamping groove 40. A plurality of mounting parts 42 are fixedly installed on the outer wall of the mounting shell 37. The mounting parts 42 and the top plate 2 are connected by bolts 43. A plurality of rollers 46 are fixedly connected to the bottom of the rotating frame 4. A support ring 44 is arranged below the top plate 2. A plurality of connecting frames 45 are fixedly connected to the bottom of the top plate 2. The bottom ends of the connecting frames 45 are fixedly connected to the support ring 44. The bottom of the rollers 46 contacts the top of the support ring 44. A load carrier 47 is arranged above the polishing table 1. A plurality of second hydraulic telescopic rods 48 are fixedly installed on the polishing table 1, and the telescopic ends of the second hydraulic telescopic rods 48 are fixedly connected to the bottom of the load carrier 47; The clamping block 41 is driven to rotate by the fourth servo motor 38. The clamping block 41 can drive the rotating frame 4 to rotate through the second rotating shaft 39. The rotating frame 4 drives the roller 46 to move on the top of the support ring 44. Through the design of the roller 46, the support ring 44 and the connecting frame 45, the rotating frame 4 can rotate stably relative to the polishing table 1, reducing the possibility of tilting and shaking of the rotating frame 4. The worker drives the bolt 43 to rotate so that the bolt 43 disengages from the mounting portion 42 and the top plate 2, releasing the fixation of the mounting shell 37. The worker drives the mounting shell 37 and the fourth servo motor 38 to move upward so that the clamping block 41 disengages from the card slot 40, and the removal of the fourth servo motor 38 can be completed. The worker places a plurality of blades welded together on the carrier seat 47 through an external feeding device. The carrier seat 47 is driven to move in the vertical direction by the second hydraulic expansion rod 48, facilitating the adjustment of the initial height of the blade according to different blade specifications and improving the scope of application.

[0020] Those of ordinary skill in the art should understand that the discussion of any above embodiment is exemplary only and is not intended to imply that the scope of the present invention is limited to these examples; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A polishing device for producing steam turbine blades, comprising a polishing table (1) and a top plate (2), characterized in that: A plurality of support plates (3) are fixedly connected to the top of the polishing table (1); the top of the support plate (3) is fixedly connected to the bottom of the top plate (2); a rotating frame (4) and a movable box (5) are provided below the top plate (2); the top plate (2) is provided with a rotation unit for driving the rotating frame (4) to rotate; the rotating frame (4) is provided with a translation mechanism for driving the movable box (5) to translate; a mounting seat (6) is provided at the bottom of the movable box (5); the movable box (5) is provided with a tilting structure for driving the mounting seat (6) to tilt; and a polisher for polishing is provided on the mounting seat (6).

2. The polishing equipment for steam turbine blade production according to claim 1, characterized in that: The tilting structure comprises a first rotating shaft (7) rotatably mounted on a rotating frame (4); a first servo motor (8) is fixedly mounted on the rotating frame (4); an output end of the first servo motor (8) is fixedly connected to the first rotating shaft (7); the first rotating shaft (7) passes through a movable box (5); a first rotating sleeve (9) is sleeved on the outside of the first rotating shaft (7); the first rotating sleeve (9) and the movable box (5) are rotatably connected; a connecting plate (11) located in the movable box (5) is fixedly mounted on the first rotating sleeve (9); a first avoidance hole (10) matched with the connecting plate (11) is opened on the inner wall of the movable box (5); the connecting plate (11) passes through the first avoidance hole (10); the connecting plate (11) and the mounting seat (6) are fixedly connected; and a damping synchronizing member for driving the first rotating sleeve (9) and the first rotating shaft (7) to rotate synchronously is mounted on the movable box (5).

3. The polishing equipment for producing steam turbine blades according to claim 2, characterized in that: The damping synchronous component comprises a second rotating sleeve (12) sleeved on the outside of the first rotating shaft (7), the second rotating sleeve (12) and the movable box (5) are rotatably connected, the first rotating shaft (7) is provided with a slide groove (14), a slider (13) is slidably arranged in the slide groove (14), and the slider (13) is fixedly connected to the inner wall of the second rotating sleeve (12), the outer fixed sleeve of the second rotating sleeve (12) is provided with a first damping ring (15) located in the movable box (5), and the outer fixed sleeve of the first rotating sleeve (9) is provided with a second damping ring (16) located in the movable box (5), and the second damping ring (16) and the first damping ring (15) are in contact.

4. The polishing equipment for producing steam turbine blades according to claim 1, characterized in that: The translation mechanism comprises a screw rod (17) rotatably mounted on the rotating frame (4); a support portion (18) is fixedly mounted on the movable box (5); the screw rod (17) passes through the support portion (18); and the screw rod (17) and the support portion (18) are connected in a threaded manner; a second servo motor (19) is fixedly mounted on the rotating frame (4); and an output end of the second servo motor (19) is fixedly connected to the screw rod (17).

5. The polishing equipment for producing steam turbine blades according to claim 1, characterized in that: The polisher comprises a third servo motor (20) fixedly mounted on the bottom of a mounting seat (6); an output end of the third servo motor (20) is fixedly connected to a prism (21); an outer sliding sleeve of the prism (21) is provided with a sliding sleeve (22); a polishing wheel (23) is provided below the sliding sleeve (22); a disassembly component compatible with the polishing wheel (23) is installed on the sliding sleeve (22); and a telescopic component compatible with the sliding sleeve (22) is installed on the mounting seat (6).

6. The polishing equipment for producing steam turbine blades according to claim 5, characterized in that: The telescopic member comprises a lifting frame (24) rotatably sleeved on the outside of the sliding sleeve (22); a first hydraulic telescopic rod (25) is fixedly mounted on the mounting seat (6); and a telescopic end of the first hydraulic telescopic rod (25) is fixedly connected to the lifting frame (24).

7. The polishing equipment for producing steam turbine blades according to claim 5, characterized in that: The disassembly and assembly component comprises a fixed sleeve (26) fixedly mounted on the outside of the sliding sleeve (22), at least three stop holes (27) being formed on the fixed sleeve (26), a second avoidance hole (28) being formed on the bottom inner wall of the stop hole (27), a stop block (29) being provided in the stop hole (27), the bottom and top of the stop block (29) respectively contacting the inner wall of the stop hole (27), a connecting block (30) being fixedly connected to the bottom of the stop block (29), the bottom of the connecting block (30) being fixedly connected to the top of the polishing wheel (23), the connecting block (30) passing through the second avoidance hole (28), the stop block (29) and the connecting block (30) respectively contacting the outer wall of the sliding sleeve (22), and the sliding sleeve (22) being provided with a stop unit adapted to the stop block (29).

8. The polishing equipment for producing steam turbine blades according to claim 7, characterized in that: The stop unit comprises a baffle (31) arranged in the stop hole (27); two sides of the stop block (29) are respectively in contact with the inner wall of the stop hole (27) and the baffle (31); an outer fixed sleeve of the sliding sleeve (22) is provided with a fixed ring (33); a movable ring (32) is provided on the top of the fixed sleeve (26); the top of the baffle (31) and the bottom of the movable ring (32) are fixedly connected; the top of the movable ring (32) and the top of the fixed ring (33) are connected via a compression spring (36); a guide groove (34) is provided on the outer wall of the sliding sleeve (22); a guide block (35) is slidably provided in the guide groove (34); and the guide block (35) and the inner wall of the movable ring (32) are fixedly connected.

9. The polishing equipment for producing steam turbine blades according to claim 1, characterized in that: The self-rotating unit comprises a mounting shell (37) arranged on the top of the top plate (2), a fourth servo motor (38) is fixedly connected inside the mounting shell (37), a second rotating shaft (39) is rotatably connected to the top plate (2), a bottom end of the second rotating shaft (39) is fixedly connected to the top of the rotating frame (4), a slot (40) is provided at the top of the second rotating shaft (39), an output end of the fourth servo motor (38) is fixedly connected to a block (41) located in the slot (40), a plurality of mounting portions (42) are fixedly mounted on the outer wall of the mounting shell (37), and the mounting portions (42) and the top plate (2) are connected by bolts (43).

10. The polishing equipment for producing steam turbine blades according to claim 1, characterized in that: A plurality of rollers (46) are fixedly connected to the bottom of the rotating frame (4), a support ring (44) is provided below the top plate (2), a plurality of connecting frames (45) are fixedly connected to the bottom of the top plate (2), the bottom end of the connecting frame (45) is fixedly connected to the support ring (44), the bottom of the roller (46) is in contact with the top of the support ring (44), a carrier seat (47) is provided above the polishing table (1), a plurality of second hydraulic telescopic rods (48) are fixedly installed on the polishing table (1), and the telescopic ends of the second hydraulic telescopic rods (48) are fixedly connected to the bottom of the carrier seat (47).

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