Welding pipe fitting for joint with gradually-changed inner diameter

Abstract

The utility model relates to the technical field of PPR (pentatricopeptide repeats) pipeline welding technology, in particular to a welding pipe fitting with a gradually-changed inner diameter joint, which comprises a pipe body, a welding medium layer is arranged in the pipe body, butt joint devices are mounted at two ends of the pipe body, each butt joint device comprises an upper butt joint block and a lower butt joint block, and the upper butt joint block and the lower butt joint block are rotationally connected with the outer wall of the pipe body. The ends, close to the end face of the pipe body, of the upper butt-joint block and the lower butt-joint block are in contact and then can be fixedly connected to define a clamping cavity, and the axis of the clamping cavity and the axis of the pipe body are collinear. According to the utility model, the butt joint of the pipe fitting and the pipeline can be realized on the premise of ensuring the butt joint precision, and the strength and the stability are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to PPR pipeline welding technical field more specifically, it relates to a gradually change inner diameter joint welding pipe fitting. BACKGROUND

[0002] Pipe fitting is the collective term of the parts in the pipeline system that play the role of connection, control, change of direction, shunt, sealing and support, pipe fitting is used for connecting water pipes of different diameters, water source is delivered to each water point, the direction of water flow can be changed to meet the demand of pipeline layout, water seal is formed to prevent odor and harmful gas from escaping, and the pipeline needs to be connected into a complete network through pipe fitting. And PPR material is a common plastic pipeline material, with excellent impact resistance, corrosion resistance and high temperature resistance, good pressure resistance, heat preservation and aging resistance, and the characteristics of health, non-toxic, easy installation, and beautiful appearance, it is widely used in building water supply and drainage, urban and rural water supply and drainage, city gas, power and optical cable sheath, industrial fluid transportation, agricultural irrigation and other construction, municipal, industrial and agricultural fields.

[0003] But the existing PPR pipe fitting in the market at present when welding, the high temperature area is the fluid plastic in the viscous flow state, when the pipe fitting and the pipeline are welded, the hot melting area of the pipe fitting and the pipeline is heated and melted by the heating die, and then the mechanical equipment is used to push the pipe fitting into the pipeline at both ends, and under the high temperature of hot melting, due to the gravity or mechanical external force, the pipeline bends, and the pipeline moves along the axial direction or deviates along the radial direction in the welding area of the pipe fitting, which leads to the misalignment of the center axis of the pipe fitting and the center axis of the pipeline, the welding structure is poor, the center axis is misaligned, under the forced insertion of the mechanical equipment, the extrusion stress between the two pipelines and the pipe fitting is larger, the stress concentration of the welding position is more significant, and the strength and stability are reduced. UTILITY MODEL CONTENTS

[0004] The utility model aims at overcoming the misalignment of the center axis of the pipe fitting and the center axis of the pipeline during welding in the prior art, and provides a gradually change inner diameter joint welding pipe fitting, which can realize the butt joint of the pipe fitting and the pipeline under the premise of ensuring the butt joint precision, and improve the strength and stability.

[0005] To solve the above technical problems, the utility model adopts the technical scheme of:

[0006] Provided is a gradually-changing inner diameter joint welding pipe, comprising a pipe body, a welding medium layer arranged in the pipe body, and a butt joint device installed at both ends of the pipe body, wherein the butt joint device comprises an upper butt joint block and a lower butt joint block, the upper butt joint block and the lower butt joint block are rotationally connected to the outer wall of the pipe body, the inner surfaces of the upper butt joint block and the lower butt joint block form a clamping cavity when the end of the upper butt joint block and the end of the lower butt joint block are connected, and the axis of the clamping cavity is collinear with the axis of the pipe body.

[0007] In the working process of the above scheme, the heating die head is used to heat and melt the hot melting area of the pipe and the inner wall of the pipeline, after the pipe and the pipeline are heated and melted, the mechanical equipment is started to push the pipeline into the opening of the pipe, when the pipeline is about to enter the pipe, the butt joint device is installed, the upper butt joint block and the lower butt joint block are rotated to make the upper butt joint block and the lower butt joint block contact with the outer wall of the pipeline, and the upper butt joint block and the lower butt joint block are fixed, after the installation of the butt joint block is completed, the pipeline is continuously pushed forward, the upper butt joint block and the lower butt joint block of the butt joint device clamp the pipeline, so that the pipeline passes through the correction of the butt joint device before entering the pipe, in the forward direction of the pipeline, the pipeline has two fulcrums of the butt joint device and the opening end surface of the pipe, and since the clamping cavity clamping the pipeline is collinear with the axis of the pipe body, the pipeline maintains the state of being collinear with the axis of the pipe body during installation, the central axis of the pipe and the central axis of the pipeline can be aligned, the pipeline can stably advance in a straight line, the welded structure after cooling will be symmetrical about the central axis, the extrusion internal stress between the pipeline and the pipe is reduced, the stress concentration is reduced, and the strength and stability are effectively improved.

[0008] Further, the installation block is fixedly connected to the outer wall of the pipe body, one end of the installation block is rotationally connected to the upper butt joint block, and the other end of the installation block is rotationally connected to the lower butt joint block; the upper butt joint block and the lower butt joint block are rotationally connected to the outer wall of the pipe body through the installation block, when the upper butt joint block or the lower butt joint block is damaged, the damaged part can be removed on the installation block, without the need to replace the entire pipe, and after the hot melting butt joint of the pipe and the pipeline is completed, the upper butt joint block and the lower butt joint block can be removed and installed on a new pipe, to realize the reuse of the parts and save costs.

[0009] Further, the upper butt joint block and the lower butt joint block are each provided with a plurality of butt joint fixing seats, and the upper butt joint block and the lower butt joint block are fixedly connected through the butt joint fixing seats; the fixed connection of the upper butt joint block and the lower butt joint block is realized by additionally installing the butt joint fixing seats, and the fixed connection is detachable, and the operator can quickly fix the two butt joint fixing seats.

[0010] Further, the butt joint fixing seats are each provided with a threaded hole, and the butt joint fixing seats of the upper butt joint block and the lower butt joint block are connected through fasteners; the fastener is a bolt, and the two butt joint fixing seats are stably fixed in a threaded connection mode.

[0011] Further, the end faces of the upper butt joint block and the lower butt joint block are provided with clamping blocks, and the inner sides of the clamping blocks are fixedly connected with anti-skid pads; the anti-skid pads of the upper and lower clamping blocks directly contact the outer wall of the pipeline, and the anti-skid pads are arranged to increase the friction between the clamping blocks and the pipeline, so that the insertion force of the mechanical equipment is reduced, the pipeline is inserted into the pipe more slowly and more smoothly, and the fusion of the hot melt adhesive is facilitated.

[0012] Further, the inner wall of the clamping block is a circular arc for abutting the outer wall of the inserted outer pipe; only when the inner wall profile of the clamping block abuts the outer wall of the pipeline can the pipeline be corrected by the butt joint device before entering the pipe.

[0013] Further, the upper butt joint block and the lower butt joint block are provided with a hollow part near one end of the pipe body center, and the profile of the hollow part is arc-shaped; the hollow part arranged in the non-working area of the upper butt joint block and the lower butt joint block can realize lightweight of the component.

[0014] Further, the outermost layer of the pipe body is an outer protective layer, and the surface of the outer protective layer is coated with an anti-ultraviolet layer; the outer protective layer will be brittle and decomposed when irradiated by high-frequency electromagnetic waves, and the anti-ultraviolet layer can avoid the brittle and decomposition of the material under light.

[0015] Further, the outer part of the fusion medium layer is provided with a corrosion-resistant layer and a reinforcing layer, the corrosion-resistant layer is fixedly connected with the fusion medium layer, the inner side of the reinforcing layer is fixedly connected with the corrosion-resistant layer, and the outer side of the reinforcing layer is fixedly connected with the outer protective layer; the corrosion-resistant layer can prevent the pipe from being corroded by corrosive substances, and the reinforcing layer is used to enhance the strength of the pipe.

[0016] Further, the inner diameter of the pipe body gradually decreases from the two open ends to the center of the pipe body, and a center block is arranged at the center of the pipe body and surrounds the outer wall of the pipe body; the pipe is close to the center, and the wall thickness is larger, and the center block is arranged at the center of the pipe to thicken the wall thickness of the center position, prolong the hot melt heating time of the die head on the inner wall of the pipe, heat the inner wall of the pipe sufficiently, and insert and connect smoothly.

[0017] Compared with the prior art, the utility model has the advantages that:

[0018] 1. The pipe body is provided with a fusion medium layer, and the butt joint device is arranged at both ends of the pipe body, the butt joint device comprises an upper butt joint block and a lower butt joint block, the upper butt joint block and the lower butt joint block are rotatably connected with the outer wall of the pipe body, the upper butt joint block and the lower butt joint block are fixedly connected after contacting one end close to the end face of the pipe body and enclose a clamping cavity, the axis of the clamping cavity is collinear with the axis of the pipe body, the fused structure after cooling is symmetrical about the center axis, the extrusion internal stress between the pipeline and the pipe is reduced, the stress concentration is reduced, and the strength and stability are effectively improved.

[0019] 2. The pipe body wall thickness of the pipe is gradually changed, the inner diameter of the two open ends of the pipe body to the center of the pipe body continuously and smoothly changes from large to small, a center block is arranged at the center of the pipe body, and the center block is arranged around the outer wall of the pipe body; the wall thickness of the pipe is larger near the center, and the wall thickness of the thickened center position is increased by arranging the center block at the center of the pipe, prolonging the heat melting heating time of the die head on the inner wall of the pipe, fully heating the inner wall of the pipe, and smoothly inserting and connecting. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 It is a perspective view of a gradually changing inner diameter joint welding pipe;

[0021] Fig. 2 It is a structural schematic view of a gradually changing inner diameter joint welding pipe in an open state of an upper butt block and a lower butt block;

[0022] Fig. 3 It is a structural schematic view of a butt joint device of a gradually changing inner diameter joint welding pipe;

[0023] Fig. 4 It is a structural schematic view of the inner wall of the pipe body of a gradually changing inner diameter joint welding pipe;

[0024] Fig. 5 It is Fig. 4 It is an enlarged view of part A in the middle.

[0025] In the drawings: 1, pipe body; 110, welding medium layer; 120, outer protective layer; 130, anticorrosion layer; 140, reinforcing layer; 150, center block; 2, butt joint device; 210, upper butt block; 220, lower butt block; 230, clamping cavity; 240, clamping block; 241, non-slip pad; 250, hollow part; 3, mounting block; 4, butt joint fixing seat. DETAILED DESCRIPTION

[0026] The utility model will be further described below in combination with specific embodiments. Among them, the drawings are only used for example description, and the representation is only a schematic diagram, not a physical drawing, and cannot be understood as a limitation of the patent; in order to better illustrate the embodiments of the utility model, some components of the drawings will be omitted, enlarged or reduced, and the size of the actual product is not represented; for those skilled in the art, it is understandable that some known structures and their descriptions in the drawings can be omitted.

[0027] The same or similar reference signs in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it is understood that if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right" and the like are based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation and be operated, therefore, the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present patent, and for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0028] Embodiment 1

[0029] The present embodiment is a first embodiment of a gradually changing inner diameter joint welding pipe, as shown in Figs. 1 to 3 the drawing, comprising a pipe body 1, a welding medium layer 110 is arranged in the pipe body 1, and a butt joint device 2 is installed at both ends of the pipe body 1, the butt joint device 2 comprises an upper butt joint block 210 and a lower butt joint block 220, the upper butt joint block 210 and the lower butt joint block 220 are both rotationally connected with the outer wall of the pipe body 1, and the inner surfaces of the upper butt joint block 210 and the lower butt joint block 220 enclose a clamping cavity 230 in the state that the ends of the upper butt joint block 210 and the lower butt joint block 220 are connected, and the axis of the clamping cavity 230 is collinear with the axis of the pipe body 1.

[0030] Specifically, the upper butt joint block 210 and the lower butt joint block 220 are both provided with a plurality of butt joint fixing seats 4, and the upper butt joint block 210 and the lower butt joint block 220 are fixedly connected through the butt joint fixing seats 4; the fixed connection of the upper butt joint block 210 and the lower butt joint block 220 is realized by additionally installing the butt joint fixing seats 4, and the fixed connection is detachable connection, and an operator can quickly fix the two butt joint fixing seats 4.

[0031] Specifically, the butt joint fixing seat 4 is provided with a threaded hole, the butt joint fixing seat 4 of the upper butt joint block 210 and the butt joint of the lower butt joint block 220 are connected through a fastener; the fastener is a bolt, and the fixed form of the threaded connection is adopted to stably fix the two butt joint fixing seats 4.

[0032] Specifically, the end surfaces of the upper butt joint block 210 and the lower butt joint block 220 are both provided with clamping blocks 240, and the inner side of the clamping block 240 is fixedly connected with an anti-skid pad 241; the anti-skid pads 241 of the upper and lower clamping blocks 240 directly contact and abut the outer wall of the pipeline, clamp the pipeline, and the setting of the anti-skid pads 241 increases the friction between the clamping blocks 240 and the pipeline, thereby reducing the insertion force of the mechanical equipment, so that the pipeline is inserted into the pipe more slowly and more gently, which is helpful for the fusion of the hot melt adhesive.

[0033] Specifically, the inner wall of the clamping block 240 is a circular arc for abutting the outer wall of the inserted outer tube; the inner wall profile of the clamping block 240 abuts the outer wall of the pipeline to enable the pipeline to pass through the correction device 2 before entering the pipe fitting.

[0034] Specifically, the upper butt block 210 and the lower butt block 220 are provided with a hollow part 250 near the end of the pipe body 1 center, and the profile of the hollow part 250 is arc-shaped; the hollow part 250 is arranged in the non-working area of the upper butt block 210 and the lower butt block 220 to achieve lightweight of the components.

[0035] The working principle of the gradually changing inner diameter joint welding pipe fitting of the embodiment is as follows:

[0036] First, the heating die head is used to heat and melt the heat melting area of the inner wall of the pipe fitting and the pipeline, and after the pipe fitting and the pipeline are heated and melted well, the mechanical equipment is started to push the pipeline into the opening of the pipe fitting, and when the pipeline is about to enter the pipe fitting, the butt joint device 2 is installed, the upper butt block 210 and the lower butt block 220 are rotated, the clamping block 240 of the upper butt block 210 and the lower butt block 220 is in contact with the outer wall of the pipeline, and after abutting the butt joint fixing seat 4, the bolts are installed to fix the upper butt block 210 and the lower butt block 220, after the installation of the butt block is completed, the pipeline is continuously pushed slowly, and the upper butt block 210 and the lower butt block 220 of the butt joint device 2 clamp the pipeline, so that the pipeline does not deviate radially.

[0037] The beneficial effects of the embodiment are as follows: after the upper butt block 210 and the lower butt block 220 contact the end near the end face of the pipe body 1, they can be fixedly connected and surround the clamping cavity 230, the axis of the clamping cavity 230 is collinear with the axis of the pipe body 1, in the advancing direction of the pipeline, the pipeline has two fulcrums of the clamping block 240 and the opening end face of the pipe fitting, the pipeline can stably advance in a straight line, the welded structure after cooling will be symmetrical about the center axis, the extrusion internal stress between the pipeline and the pipe fitting is reduced, the stress concentration is reduced, and the strength and stability are effectively improved.

[0038] Embodiment 2

[0039] The embodiment is a second embodiment of a gradually changing inner diameter joint welding pipe fitting, as shown in Figs. 3 to 5 the drawing, comprising a pipe body 1, the pipe body 1 is provided with a welding medium layer 110, and the two ends of the pipe body 1 are provided with butt joint devices 2, the butt joint devices 2 comprise upper butt blocks 210 and lower butt blocks 220, the upper butt blocks 210 and the lower butt blocks 220 are rotationally connected with the outer wall of the pipe body 1, and the inner surfaces of the upper butt blocks 210 and the lower butt blocks 220 surround a clamping cavity 230 in a state that the ends of the upper butt blocks 210 and the lower butt blocks 220 are connected, and the axis of the clamping cavity 230 is collinear with the axis of the pipe body 1.

[0040] Specifically, the upper butt joint block 210 and the lower butt joint block 220 are provided with a plurality of butt joint fixing seats 4, and the upper butt joint block 210 and the lower butt joint block 220 are fixedly connected through the butt joint fixing seats 4. The fixed connection of the upper butt joint block 210 and the lower butt joint block 220 is realized by additionally installing the butt joint fixing seats 4, and the fixed connection is detachable connection, and the operator can quickly fix the two butt joint fixing seats 4.

[0041] Specifically, the butt joint fixing seat 4 is provided with a threaded hole, and the butt joint fixing seat 4 of the upper butt joint block 210 and the butt joint of the lower butt joint block 220 are connected through a fastener. The fastener is a bolt, and the fixed form of the threaded connection is adopted to stably fix the two butt joint fixing seats 4.

[0042] Specifically, the outermost layer of the pipe body 1 is an outer protective layer 120, and the surface of the outer protective layer 120 is coated with an anti-ultraviolet layer. The outer protective layer 120 will appear material embrittlement and decomposition under the irradiation of high-frequency electromagnetic waves. The setting of the anti-ultraviolet layer can avoid the light embrittlement and decomposition of the material.

[0043] Specifically, the outer part of the fusion medium layer 110 is provided with a corrosion-resistant layer 130 and a reinforcing layer 140, the corrosion-resistant layer 130 is fixedly connected with the fusion medium layer 110, the inner side of the reinforcing layer 140 is fixedly connected with the corrosion-resistant layer 130, and the outer side of the reinforcing layer 140 is fixedly connected with the outer protective layer 120. The setting of the corrosion-resistant layer 130 can avoid the corrosion of the pipe fitting by corrosive substances, and the reinforcing layer 140 is used to enhance the strength of the pipe fitting.

[0044] The working principle of the gradually changing inner diameter joint fusion pipe fitting of the embodiment is as follows:

[0045] The fusion medium layer 110 is preheated and melted during hot fusion butt joint. After the upper butt joint block 210 and the lower butt joint block 220 complete the hot fusion butt joint of the pipeline, the corrosion-resistant layer 130 prevents the pipeline from being corroded by corrosive substances, and the reinforcing layer enhances the strength of the pipeline

[0046] The beneficial effects of the embodiment are that the corrosion-resistant layer 130 and the reinforcing layer are set to effectively improve the corrosion resistance and strength of the pipe fitting, so that the service life of the pipe fitting is longer and more durable.

[0047] Embodiment 3

[0048] The embodiment is a third embodiment of a gradually changing inner diameter joint fusion pipe fitting, as shown in Figs. 2 to 5As shown, including the pipe body 1, the pipe body 1 is provided with a welding medium layer 110, both ends of the pipe body 1 are provided with a butt joint device 2, the butt joint device 2 includes an upper butt joint block 210 and a lower butt joint block 220, the upper butt joint block 210 and the lower butt joint block 220 are rotatably connected with the outer wall of the pipe body 1, the inner surfaces of the upper butt joint block 210 and the lower butt joint block 220 enclose a clamping cavity 230 in the state that the ends of the upper butt joint block 210 and the lower butt joint block 220 are connected, and the axis of the clamping cavity 230 is collinear with the axis of the pipe body 1.

[0049] Specifically, the upper butt joint block 210 and the lower butt joint block 220 are provided with a plurality of butt joint fixing seats 4, and the upper butt joint block 210 and the lower butt joint block 220 are fixedly connected through the butt joint fixing seats 4; the fixed connection of the upper butt joint block 210 and the lower butt joint block 220 is realized by additionally installing the butt joint fixing seats 4, and the fixed connection is detachable connection, and the operator can quickly fix the two butt joint fixing seats 4.

[0050] Specifically, the butt joint fixing seat 4 is provided with a threaded hole, the butt joint fixing seat 4 of the upper butt joint block 210 and the butt joint fixing seat 4 of the lower butt joint block 220 are connected through a fastener; the fastener is a bolt, and the fixed form of the threaded connection is adopted to stably fix the two butt joint fixing seats 4.

[0051] Specifically, the inner diameter of the pipe body 1 gradually decreases from the two open ends to the center of the pipe body 1, the center block 150 is arranged at the center of the pipe body 1, and the center block 150 is arranged around the outer wall of the pipe body 1; the wall thickness of the pipe near the center is larger, and the center block 150 is arranged at the center of the pipe to thicken the wall thickness of the center position, prolong the hot melting heating time of the die head on the inner wall of the pipe, and heat the inner wall of the pipe sufficiently and smoothly.

[0052] The working principle of the gradually changing inner diameter joint welding pipe of the embodiment is as follows:

[0053] The inner diameter of the pipe body 1 continuously and smoothly changes from the two open ends to the center of the pipe body 1 and decreases from large to small, the inner wall of the center of the pipe is thicker during heating, and compared with the two ends of the pipe, the center of the pipe can be heated for a longer time without melting the outer wall of the pipe, the long-time heating can make the molten glue at the center of the pipe flow better, which is more conducive to the insertion hot melting butt joint of the pipeline, the insertion resistance is smaller, the required insertion force is smaller, and the internal extrusion stress is reduced.

[0054] The beneficial effects of the embodiment are as follows: the inner diameter of the two open ends of the pipe body 1 to the center of the pipe body 1 continuously and smoothly changes from large to small, the center block 150 is arranged at the center of the pipe body 1, the center block 150 is arranged around the outer wall of the pipe body 1, the pipe is close to the center, the wall thickness is larger, and the center block 150 is arranged at the center of the pipe to thicken the wall thickness of the center position, prolong the hot melting heating time of the die head to the inner wall of the pipe, heat the inner wall of the pipe sufficiently, insert and connect smoothly, reduce the internal extrusion stress, and reduce the stress concentration degree.

[0055] In the specific contents of the above specific embodiments, any non-contradictory combination of technical features can be combined, in order to make the description simple, not all possible combinations of the above technical features are described, however, as long as the combination of the technical features does not exist Contradiction, it should be considered as the scope disclosed in the specification.

[0056] Obviously, the above embodiments of the application are only examples for clearly illustrating the application, and are not intended to limit the embodiments of the application. Based on the above description, those skilled in the art can make other different forms of changes or modifications. Here, all the embodiments need not and cannot be exhausted. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the claims of the application.

Claims

1. A fusion pipe of a gradually changing inner diameter joint, comprising a pipe body (1) provided with a fusion medium layer (110) inside, characterized in that, Both ends of the pipe body (1) are provided with butt joint devices (2), the butt joint devices (2) comprise upper butt joint blocks (210) and lower butt joint blocks (220), the upper butt joint blocks (210) and the lower butt joint blocks (220) are rotatably connected with the outer wall of the pipe body (1), the inner surfaces of the upper butt joint blocks (210) and the lower butt joint blocks (220) enclose clamping cavities (230) when the ends of the upper butt joint blocks (210) and the lower butt joint blocks (220) are connected, the axis of the clamping cavities (230) is collinear with the axis of the pipe body (1).

2. A GRADUATED-INTERNAL-DIAMETER FITTING WELDED TUBE as claimed in claim 1, characterized in that, Further comprising mounting blocks (3), the mounting blocks (3) are fixedly connected with the outer wall of the pipe body (1), one end of the mounting blocks (3) is rotatably connected with the upper butt joint blocks (210), and the other end is rotatably connected with the lower butt joint blocks (220).

3. A GRAD OD adapter welded pipe according to claim 1, characterized in that, The upper butt joint blocks (210) and the lower butt joint blocks (220) are provided with a plurality of butt joint fixing seats (4), and the upper butt joint blocks (210) and the lower butt joint blocks (220) are fixedly connected through the butt joint fixing seats (4).

4. A GRADUATED-INTERNAL-DIAMETER FITTING WELDED TUBE as claimed in claim 3, characterized in that, The butt joint fixing seats (4) are provided with threaded holes, and the butt joint fixing seats (4) of the upper butt joint blocks (210) and the lower butt joint blocks (220) are connected through fasteners.

5. A GRAD OD adapter welded pipe as defined in claim 1, wherein, The end faces of the upper butt joint blocks (210) and the lower butt joint blocks (220) are provided with clamping blocks (240), and the inner sides of the clamping blocks (240) are fixedly connected with anti-skid pads (241).

6. A GRADUATED-INTERNAL-DIAMETER FITTING WELDED TUBE as claimed in claim 5, characterized in that, The inner walls of the clamping blocks (240) are circular arcs for abutting the outer walls of inserted outer pipes.

7. A GRADUATED-INTERNAL-DIAMETER SLEEVE FOR WELDING PIPE, according to claim 1, characterized in that, The upper butt joint blocks (210) and the lower butt joint blocks (220) are provided with hollow parts (250) near one end of the pipe body (1) center, and the outlines of the hollow parts (250) are arc-shaped.

8. A fusion joint of a tapered inner diameter fitting according to any one of claims 1 to 6, wherein The outermost layer of the pipe body (1) is an outer protective layer (120), and the surface of the outer protective layer (120) is coated with an ultraviolet protection layer.

9. A GRADUATED-INTERNAL-DIAMETER SLEEVE FOR WELDING PIPES, according to claim 8, characterized in that, The outer part of the fusion medium layer (110) is provided with a corrosion-resistant layer (130) and a reinforcing layer (140), the corrosion-resistant layer (130) is fixedly connected with the fusion medium layer (110), the inner side of the reinforcing layer (140) is fixedly connected with the corrosion-resistant layer (130), and the outer side of the reinforcing layer (140) is fixedly connected with the outer protective layer (120).

10. A fusion joint of a tapered ID fitting according to any one of claims 1-6, wherein, The inner diameters of the two open ends of the pipe body (1) to the center of the pipe body (1) gradually decrease, and the center block (150) is arranged at the center of the pipe body (1), and the center block (150) is arranged around the outer wall of the pipe body (1).

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