Gas pipeline welding butt joint device
The gas pipeline welding and docking device, which combines a hexagonal surround clamping frame and an electric actuator, solves the problems of difficult centering and unstable lifting in the welding of large-diameter pipelines, and achieves high-quality welding and safe construction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-24
- Publication Date
- 2026-03-24
AI Technical Summary
Existing gas pipeline welding and butt welding devices suffer from difficulties in centering and adjustment, unstable clamping and fixing, and lack of stability in lifting and adjusting during the construction of large-diameter pipelines, resulting in poor welding quality.
It adopts a hexagonal surround clamping frame, a fixed support plate driven by a handwheel screw, a guide rod to limit the direction of movement, and a lifting component that works with a transverse guide rail and an electric push rod. Combined with rubber pads and flexible pads, it can achieve stable clamping and precise adjustment in all directions.
It enables precise centering and clamping of large-diameter gas pipelines, preventing shaking during welding, reducing the labor intensity of workers, improving construction efficiency, and protecting the pipeline surface from mechanical damage.
Smart Images
Figure CN224026890U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to pipeline construction equipment technical field especially, relates to a gas pipeline welding butt joint device. BACKGROUND
[0002] In the laying construction process of gas pipeline, the welding quality between the pipeline is directly related to the operation safety and service life of the whole gas pipeline network, especially for large diameter and thick wall thickness gas pipeline, its single weight is huge, when carrying out the end butt joint operation of two pipelines, it must be guaranteed that the coaxiality and butt joint stability are extremely high, otherwise it is easy to produce weld defects and thus bury the security risks.
[0003] At present, when carrying out pipeline butt joint in the construction site, still mostly adopts the way of hoisting mechanical lifting cooperation manual adjustment, this traditional operation mode not only is high in labor intensity, high in risk coefficient, and because of lacking special precision adjusting equipment, it is difficult to accurately control the displacement of pipeline in small range, leads to the centering efficiency extremely low, in addition, the existing simple support tool often only has single supporting function, cannot firmly lock the pipeline as the reference in whole circumference, leads to its easy to roll or deviate in the welding process, and when adjusting the height of another pipeline, lacks the lifting structure with guiding constraint, it is easy to produce shaking or inclination because of the load is too heavy, cannot satisfy the demand of high quality welding construction.
[0004] Therefore the utility model provides a gas pipeline welding butt joint device to solve the insufficient of prior art. UTILITY MODEL CONTENT
[0005] In view of the pipeline centering adjustment difficulty, clamping fixation instability and the welding quality problem of poor quality caused by the lack of stability of lifting adjustment of the gas pipeline welding butt joint device in the prior art, the utility model aims at providing a gas pipeline welding butt joint device with improved structure, which can effectively solve the above problems.
[0006] The utility model provides a kind of gas pipeline welding butt joint device, comprising: support one, support two, connecting frame, lower positioning frame and upper positioning frame, connecting frame is fixedly connected on the support one, the lower positioning frame and the upper positioning frame are fixedly connected on the connecting frame, the inclined plane of the lower positioning frame and the upper positioning frame is fixedly connected with adjusting frame, adjusting frame is rotatably connected with screw rod in, screw rod is threadedly connected with sleeve on, the bottom of sleeve is fixedly connected with fixed support piece, the outside of fixed support piece is fixedly connected with guide rod, the guide rod is slidably connected with the lower positioning frame and the upper positioning frame respectively, the top of support two is fixedly connected with horizontal moving guide rail, horizontal moving guide rail is slidably connected with horizontal moving seat, the top of horizontal moving seat is fixedly connected with electric push rod and guide rail, the output end of electric push rod is fixedly connected with lifting frame, the bottom of lifting frame is fixedly connected with guide frame, guide frame is slidably connected with guide rail.
[0007] Preferably, the top end of the screw rod extends to the outside through the adjusting frame, and the top end of the screw rod is fixedly connected with a hand wheel, so that the operator can intuitively and accurately drive the screw rod to rotate by manually rotating, thereby driving the fixed support piece to move.
[0008] Preferably, the inner side of the fixed support piece is fixedly connected with a rubber gasket, which is arranged on the side of the fixed support piece in contact with the gas pipeline. The arrangement of the rubber gasket not only increases the static friction force with the outer wall of the gas pipeline by elastic deformation of the material, but also prevents the pipeline from slipping. In addition, the rubber gasket can prevent the corrosion layer on the surface of the gas pipeline from being damaged by direct hard contact of the metal support piece under strong clamping force.
[0009] Preferably, the top of the support one is fixedly connected with a support on both sides, the support is located outside the connecting frame, the top surface of the support is concave arc-shaped structure, the arrangement of the support can provide preliminary auxiliary support when the first gas pipeline enters the clamping space, and the concave arc surface can naturally fit the outer circle of the pipeline, effectively guiding the pipeline into the device main body and preventing the pipeline from bumping into the edge structure during movement.
[0010] Preferably, the lifting frame is in semicircular arc structure, the top inside of the lifting frame is fixedly connected with a pad strip, the pad strip is distributed along the arc surface of the lifting frame, and the pad strip distributed in this way can provide multi-point flexible contact when supporting the pipeline, avoiding local stress concentration caused by manufacturing errors in full surface contact, while also increasing the roughness of the contact surface to prevent axial slipping of the pipeline during lifting.
[0011] Preferably, the lower positioning frame and the upper positioning frame are assembled into a hexagonal surrounding clamping frame through the connecting frame, the sleeve is arranged in the mounting groove in the inclined surface of the lower positioning frame and the upper positioning frame, and the force distribution of the hexagonal frame structure is more uniform than that of a traditional two-point clamp, so that the hexagonal frame structure can adapt to the slight change of different pipe diameters and realize the stable and tight clamping of the whole circumference of the circular pipeline by cooperating with the four-direction screw rod propulsion.
[0012] Preferably, the number of the horizontal moving guide rails is two, and the horizontal moving guide rails are fixed in parallel on the top of the second support, and the bottom of the horizontal moving seat is provided with sliding blocks matched with the horizontal moving guide rails, so that the structure of the double-rail matched sliding blocks provides straightness and stability for horizontal movement under heavy load, eliminates the lateral torsion that may be caused by a single guide rail, and ensures accurate fitting during butt joint.
[0013] Preferably, the guide rails are vertically fixed on the two sides of the top of the horizontal moving seat, the number of the electric push rods is two and the electric push rods are fixed in the center of the horizontal moving seat, and the number of the guide frames is four and the guide frames are fixed on the two sides of the bottom of the lifting frame correspondingly, so that the double electric push rods provide strong lifting power, the constraint of the four groups of guide frames on the two sides and the guide rails can effectively resist the tilting moment caused by the gravity center deviation even under the condition of heavy load, and the lifting process is absolutely stable.
[0014] The utility model has the following beneficial effects:
[0015] 1. The utility model discloses a hexagonal surrounding clamping frame assembled by connecting frames is arranged on the fixed end, and a fixed supporting piece driven by a hand wheel and a screw rod is arranged on the inclined surface of the frame, and the movement direction of the fixed supporting piece is limited by cooperating with a guide rod, so that the problems of uneven stress, easy displacement and poor centering accuracy of the large-diameter gas pipeline during welding and fixing in the prior art are solved, the pipeline outer wall can be stably pressed from multiple directions at the same time, the pipeline is firmly centered and clamped, the pipeline is prevented from shaking during welding, and the welding quality is ensured.
[0016] 2. The utility model discloses that horizontal moving guide rails, a horizontal moving seat and an electric lifting assembly with a guide auxiliary structure are arranged on the adjusting end, so that the problems of difficult manual carrying and adjusting, low centering efficiency and insufficient stability of the lifting rod during butt joint of the heavy gas pipeline in the prior art are solved, the height and axial position of the pipeline to be butt jointed can be accurately adjusted, the lateral deviation and shaking during lifting are eliminated by cooperating the guide frame with the guide rail, the center axes of the two pipelines are accurately aligned and the end portions are closely fitted, the labor intensity of workers is reduced, and the construction efficiency is improved.
[0017] 3. The utility model discloses a rubber gasket is arranged in the fixed support piece inboard, sets up the soft pad strip in the lifting frame inboard and sets up the concave arc-shaped holder at the support top entrance, solves the problem that the metal clamp or support of prior art directly contacts the pipeline and is easy to scratch the pipeline surface anticorrosive coating, reaches the effect that guaranteeing effective support and powerful clamping, buffering pressure and increasing friction with flexible contact surface at the same time, all -round protection gas pipeline outer wall from mechanical damage, ensures the pipeline construction safety. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 A kind of gas pipeline welding butt joint device is provided for the utility model, and its sectional view is shown in the figure;
[0019] Figure 2 The structure diagram of lower positioning frame in a kind of gas pipeline welding butt joint device is provided for the utility model;
[0020] Figure 3 The sectional view of upper positioning frame in a kind of gas pipeline welding butt joint device is provided for the utility model;
[0021] Figure 4 The sectional view of horizontal moving seat in a kind of gas pipeline welding butt joint device is provided for the utility model.
[0022] Legend:
[0023] 1, support one;2, holder;3, lower positioning frame;4, connecting frame;5, upper positioning frame;6, adjusting frame;7, screw;8, hand wheel;9, sleeve;10, guide rod;11, fixed support piece;12, rubber gasket;13, support two;14, horizontal moving guide rail;15, horizontal moving seat;16, electric push rod;17, lifting frame;18, pad strip;19, guide frame;20, guide rail. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the following will combine the drawings in the embodiment of the utility model, and the technical scheme in the embodiment of the utility model is described clearly and completely. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all embodiments. Based on the embodiment in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of the utility model protection.
[0025] Embodiment:
[0026] Please refer to Figures 1 to 4The utility model embodiment provides a kind of gas pipeline welding butt joint device, it aims at solving the problems of difficult centering, inconvenient height adjustment and lack of stable full circumferential clamping and accurate three-dimensional position adjustment auxiliary device that can be realized simultaneously in the butt joint construction of large-diameter gas pipeline in prior art.
[0027] Please refer to Figure 1 And Figure 2 Gas pipeline welding butt joint device includes support one 1 as the main fixed end base, and support two 13 is set to one side of support one 1 as butt joint adjustment base, the top of support one 1 both sides are fixedly connected with guard 2, guard 2 is located at the outside of connecting frame 4 and the top surface of guard 2 is concave arc structure, guard 2 is used for auxiliary support pipeline and avoid pipeline knock damage device edge, connecting frame 4 is fixedly connected on support one 1, connecting frame 4 is fixedly connected with lower positioning frame 3 and upper positioning frame 5, lower positioning frame 3 and upper positioning frame 5 are assembled to form a six-sided ring type clamping frame by connecting frame 4, lower positioning frame 3 and upper positioning frame 5 are used to build the clamping space containing first gas pipeline.
[0028] Please refer to Figure 1 And Figure 3 The inclined plane of lower positioning frame 3 and upper positioning frame 5 is fixedly connected with adjusting frame 6, adjusting frame 6 is rotatably connected with screw 7 in, screw 7 is threadedly connected with sleeve 9, sleeve 9 is arranged in the installation groove in the inclined plane of lower positioning frame 3 and upper positioning frame 5, the top end of screw 7 passes through adjusting frame 6 and extends to outside, the top end of screw 7 is fixedly connected with hand wheel 8, drives screw 7 rotation by rotating hand wheel 8, the bottom of sleeve 9 is fixedly connected with fixed support sheet 11, the outside of fixed support sheet 11 is fixedly connected with guide rod 10, guide rod 10 is slidably connected with lower positioning frame 3 and upper positioning frame 5 respectively, guide rod 10 is used to limit the moving direction of fixed support sheet 11 to ensure along linear feed, the inner side of fixed support sheet 11 is fixedly connected with rubber pad 12, rubber pad 12 is arranged on the side of fixed support sheet 11 and gas pipeline contact, rubber pad 12 is used to increase friction and protect the outer wall of pipeline.
[0029] Please refer to Figure 1 And Figure 4The top of the second support 13 is fixedly connected with horizontal moving guide rails 14, the number of the horizontal moving guide rails 14 is two and the horizontal moving guide rails 14 are fixedly arranged on the top of the second support 13 in parallel, a horizontal moving seat 15 is slidably connected with the horizontal moving guide rails 14, the bottom of the horizontal moving seat 15 is provided with sliding blocks matched with the horizontal moving guide rails 14 for sliding, the horizontal moving seat 15 can move along the axis direction of the gas pipeline, the top of the horizontal moving seat 15 is fixedly connected with electric push rods 16 and guide rails 20, the guide rails 20 are vertically fixedly arranged on the two sides of the top of the horizontal moving seat 15, the number of the electric push rods 16 is two and the electric push rods 16 are fixedly arranged on the center of the horizontal moving seat 15, the output ends of the electric push rods 16 are fixedly connected with lifting frames 17, the lifting frames 17 are in semicircular arc structures, the top inner side of the lifting frames 17 is fixedly connected with pad strips 18, the pad strips 18 are distributed on the arc surfaces of the lifting frames 17 in intervals, the bottom of the lifting frame 17 is fixedly connected with guide frames 19, the number of the guide frames 19 is four and the guide frames 19 are fixedly arranged on the two sides of the bottom of the lifting frame 17, the guide frames 19 are slidably connected with the guide rails 20, and the guide frames 19 and the guide rails 20 are matched to provide vertical direction guiding constraint when the electric push rods 16 drive the lifting frames 17 to move up and down.
[0030] Please refer to Figure 1 and Figure 3 The adjusting frame 6 is fixedly connected with the inclined surfaces of the lower positioning frame 3 and the upper positioning frame 5, the screw rod 7 is rotatably connected with the inner side of the adjusting frame 6, the sleeve 9 is threadedly connected with the rod body of the screw rod 7, the sleeve 9 is arranged in the installation groove in the inner side of the inclined surfaces of the lower positioning frame 3 and the upper positioning frame 5, the bottom of the sleeve 9 is fixedly connected with a fixed support piece 11, the outer side of the fixed support piece 11 is fixedly connected with a guide rod 10, the guide rod 10 is slidably connected with the lower positioning frame 3 and the upper positioning frame 5, the guide rod 10 penetrates through the inclined surface walls of the lower positioning frame 3 and the upper positioning frame 5, and the guide rod 10 is used for cooperating with the screw rod 7 to limit the rotation freedom of the fixed support piece 11, so that the fixed support piece 11 can keep a stable posture during feeding.
[0031] The inner side of the fixed support piece 11 is fixedly connected with a rubber pad 12, the rubber pad 12 faces the outer wall of the gas pipeline, the top end of the screw rod 7 penetrates through the adjusting frame 6 and extends to the outside, the top end of the screw rod 7 is fixedly connected with a hand wheel 8, the hand wheel 8 is used as a power input end, the screw rod 7 is driven to rotate in place by rotating the hand wheel 8 manually, the screw rod 7 drives the sleeve 9 and the fixed support piece 11 to reciprocate along the axis direction of the screw rod 7 through thread driving, so as to drive the rubber pad 12 to abut against or release the gas pipeline, and the multiple fixed support pieces 11 distributed on the hexagonal frame are used to realize the centering and clamping of the gas pipeline.
[0032] As a preferred embodiment, please refer to Figure 3 The top end of the screw rod 7 penetrates through the adjusting frame 6 and extends to the outside, the top end of the screw rod 7 is fixedly connected with a hand wheel 8, the hand wheel 8 is used to provide a force point for manual rotation, the screw rod 7 is driven to rotate by rotating the hand wheel 8, and the sleeve 9 is driven to move through thread transmission.
[0033] As another preferred implementation, please refer to Figure 3 The inner side of the fixed support sheet 11 is fixedly connected with a rubber gasket 12, which is arranged on the side of the fixed support sheet 11 in contact with the gas pipeline. The rubber gasket 12 is made of elastic rubber material and can deform to tightly fit the surface of the pipeline when compressed.
[0034] As another preferred implementation, please refer to Figure 2 The top of the bracket 1 is fixedly connected with a support 2 on both sides, which is located outside the connecting frame 4. The top surface of the support 2 is concave arc-shaped structure, which can naturally fit the outer wall of the cylindrical pipeline, and plays a role of pre-positioning and buffer protection.
[0035] As another preferred implementation, please refer to Figure 4 The lifting frame 17 is semicircular arc-shaped structure, the top inside of the lifting frame 17 is fixedly connected with a pad strip 18, the pad strip 18 is distributed along the arc surface of the lifting frame 17, the pad strip 18 is made of soft material, and the plurality of pad strips 18 collectively constitute a flexible support surface.
[0036] As another preferred implementation, please refer to Figure 1 The lower positioning frame 3 and the upper positioning frame 5 are assembled to form a hexagonal ring-shaped clamping frame through the connecting frame 4. The sleeve 9 is arranged in the installation groove inside the inclined surface of the lower positioning frame 3 and the upper positioning frame 5. The hexagonal frame structure is uniformly stressed, and can be matched with the six-direction fixed support sheet 11 to realize the all-around clamping of the pipeline.
[0037] As another preferred implementation, please refer to Figure 4 The number of horizontal guide rails 14 is two and is fixed in parallel on the top of the bracket 2. The bottom of the horizontal moving seat 15 is provided with a sliding block matched with the horizontal guide rail 14 for sliding. The cooperation of the sliding block and the horizontal guide rail 14 limits the horizontal moving seat 15 to move linearly along the length direction of the horizontal guide rail 14, ensuring the straightness during the butt joint process.
[0038] As another preferred implementation, please refer to Figure 4 The guide rails 20 are vertically fixed on both sides of the top of the horizontal moving seat 15. The number of electric push rods 16 is two and is fixed in the center of the horizontal moving seat 15. The number of guide frames 19 is four and is fixed on both sides of the bottom of the lifting frame 17 correspondingly. The guide frame 19 is slidingly connected with the guide rail 20, forming a stable four-point guide structure to assist the electric push rod 16 to stably lift the heavy gas pipeline.
[0039] Working principle: when the welding work of gas pipeline is carried out, first, the first gas pipeline to be welded is inserted into the hexagonal clamping space composed of the lower positioning frame 3 and the upper positioning frame 5, the first gas pipeline is placed on the support 2 for auxiliary support, then the hand wheels 8 are manually rotated, the hand wheels 8 drive the screw rods 7 to rotate, the screw rods 7 drive the sleeves 9 to advance inward through threaded transmission, the sleeves 9 drive the fixed support plates 11 and rubber pads 12 to move to the center from four directions at the same time and press the outer wall of the first gas pipeline, and the four-point surrounding clamping is used to realize the firm centering and locking of the first gas pipeline;
[0040] When the first gas pipeline is fixed, the second gas pipeline to be butt-jointed is placed in the lifting frame 17 above the support 2, the second gas pipeline is supported by the pad 18, at this time, the electric push rod 16 is started, the electric push rod 16 drives the lifting frame 17 to move in the vertical direction, the guide frame 19 and the guide rail 20 cooperate with each other to slide during the lifting of the lifting frame 17, which provides lateral constraint for the lifting frame 17 and prevents the lifting frame 17 from shaking, the height of the second gas pipeline is adjusted by controlling the extension amount of the electric push rod 16, until the center axis of the second gas pipeline is aligned with the center axis of the first gas pipeline in height;
[0041] When the height alignment is completed, the horizontal moving seat 15 is manually pushed, the slider at the bottom of the horizontal moving seat 15 slides along the horizontal moving rail 14, drives the horizontal moving seat 15, the electric push rod 16 and the second gas pipeline to translate as a whole to the direction of the support 1, until the end of the second gas pipeline is horizontally attached to the end of the first gas pipeline, after the alignment and attachment are completed, the welding work can be carried out, and the split type clamping and adjusting structure effectively solves the problems of difficult centering and inconvenient height adjustment when the large diameter gas pipeline is butt-jointed.
Claims
1. A gas pipeline welding butt joint device, comprising a support one (1) and a support two (13), a connecting frame (4) is fixedly connected on the support one (1), an upper positioning frame (5) is fixedly connected on the top of the connecting frame (4), and a lower positioning frame (3) is fixedly connected on the bottom of the connecting frame (4); characterized in that, The slope of the lower positioning frame (3) and the upper positioning frame (5) is fixedly connected with an adjusting frame (6), the adjusting frame (6) is rotatably connected with a screw rod (7), the screw rod (7) is threadedly connected with a sleeve (9), the bottom of the sleeve (9) is fixedly connected with a fixed supporting piece (11), the outer side of the fixed supporting piece (11) is fixedly connected with a guide rod (10), and the guide rod (10) is slidably connected with the lower positioning frame (3) and the upper positioning frame (5). The top of the support two (13) is fixedly connected with a transverse guide rail (14), the transverse guide rail (14) is slidably connected with a transverse seat (15), the top of the transverse seat (15) is fixedly connected with a guide rail (20) around, the top of the transverse seat (15) is fixedly connected with an electric push rod (16), the output end of the electric push rod (16) is fixedly connected with a lifting frame (17), the bottom of the lifting frame (17) is fixedly connected with a guide frame (19), and the guide frame (19) is slidably connected with the guide rail (20).
2. A gas pipe welding butt joint device according to claim 1, characterized in that The top end of the screw rod (7) penetrates through the adjusting frame (6) and extends to the outside, and the top end of the screw rod (7) is fixedly connected with a hand wheel (8).
3. A gas pipe welding butt joint device according to claim 1, characterized in that The inner side of the fixed supporting piece (11) is fixedly connected with a rubber pad (12), and the rubber pad (12) is arranged on the side of the fixed supporting piece (11) in contact with the gas pipeline.
4. A gas pipe welding butt joint device according to claim 1, characterized in that, The top of the support one (1) is fixedly connected with a support (2) on both sides, the support (2) is located on the outer side of the connecting frame (4), and the top surface of the support (2) is an inner concave arc structure.
5. A gas pipe welding butt joint device according to claim 1, characterized in that, The lifting frame (17) is a semicircular arc structure, the top inner side of the lifting frame (17) is fixedly connected with a pad strip (18), and the pad strip (18) is distributed along the arc surface of the lifting frame (17) at intervals.
6. A gas pipe welding butt joint device according to claim 1, characterized in that The lower positioning frame (3) and the upper positioning frame (5) are assembled into a hexagonal surrounding clamping frame through the connecting frame (4), and the sleeve (9) is arranged in the mounting groove in the inner side of the slope of the lower positioning frame (3) and the upper positioning frame (5).
7. A gas pipe welding butt joint device according to claim 1, characterized in that, The number of the transverse guide rails (14) is two and they are fixed in parallel on the top of the support two (13), and the bottom of the transverse seat (15) is provided with a sliding block matched with the transverse guide rails (14) for sliding.
8. A gas pipe welding butt joint device according to claim 1, characterized in that The guide rails (20) are vertically fixed on both sides of the top of the transverse seat (15), the number of the electric push rods (16) is two and they are fixed in the center of the transverse seat (15), and the number of the guide frames (19) is four and they are fixed on both sides of the bottom of the lifting frame (17) correspondingly. The top end of the screw rod (7) penetrates through the adjusting frame (6) and extends to the outside, and the top end of the screw rod (7) is fixedly connected with a hand wheel (8). The inner side of the fixed supporting piece (11) is fixedly connected with a rubber pad (12), and the rubber pad (12) is arranged on the side of the fixed supporting piece (11) in contact with the gas pipeline. The top of the support one (1) is fixedly connected with a support (2) on both sides, the support (2) is located on the outer side of the connecting frame (4), and the top surface of the support (2) is an inner concave arc structure. The lifting frame (17) is a semicircular arc structure, the top inner side of the lifting frame (17) is fixedly connected with a pad strip (18), and the pad strip (18) is distributed along the arc surface of the lifting frame (17) at intervals. The lower positioning frame (3) and the upper positioning frame (5) are assembled into a hexagonal surrounding clamping frame through the connecting frame (4), and the sleeve (9) is arranged in the mounting groove in the inner side of the slope of the lower positioning frame (3) and the upper positioning frame (5). The number of the transverse guide rails (14) is two and they are fixed in parallel on the top of the support two (13), and the bottom of the transverse seat (15) is provided with a sliding block matched with the transverse guide rails (14) for sliding. The guide rails (20) are vertically fixed on both sides of the top of the transverse seat (15), the number of the electric push rods (16) is two and they are fixed in the center of the transverse seat (15), and the number of the guide frames (19) is four and they are fixed on both sides of the bottom of the lifting frame (17) correspondingly.