PPR pipe fitting capable of preventing low-temperature brittle cracking and pipe body connecting assembly

Abstract

The utility model relates to a PPR (pentatricopeptide repeats) pipe fitting capable of preventing low-temperature brittle cracking, which is used for connecting pipes and comprises a pipe inserting part and a reducing part, wherein the pipe inserting part is used for being connected with a pipe in a hot melting and inserting mode, the reducing part comprises a glue bearing groove used for containing welding overflowing glue and a connecting inclined face used for being connected with parts with different diameters, and the glue bearing groove comprises a guiding inclined face with one end making contact with a pipe body and a stop block located in the center of the glue bearing groove and used for limiting. Wherein the guide inclined surface is used for changing the thicknesses of different positions of the glue bearing groove to adapt to different ring stress requirements, and the stop block is used for limiting to prevent a pipe from being inserted too deep; according to the utility model, the reducing part is arranged at the welding part, and the glue bearing groove is formed in the reducing part, so that the problem that the pipe fitting is easy to brittle and crack in a low-temperature test due to stress concentration generated by extrusion of overflowing glue and the pipe fitting in a hot-melting socket-and-spigot process is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of pipeline connection, in particular to an anti-low-temperature brittle cracking PPR pipe fitting and a pipe body connection assembly. Background Art

[0002] At present, the hot melt socket technology is widely used in the field of pipeline connection. Generally, the outer wall of the pipe and the inner wall of the pipe fitting are first melted by a heating die head and then quickly inserted. The whole process is simple, fast and low-cost. However, for the current PPR hot melt socket pipe fittings, if the hot melt time is insufficient and the inner diameter size is small during the hot melt socket process, during the forced socket process of the machine, stress concentration occurs between the pipe and the pipe fitting, resulting in brittle cracking problems, so that the cold water hydraulic test cannot meet the set requirements in the later stage. Content of the Utility Model

[0003] The purpose of the utility model is to overcome the problem of low-temperature brittle cracking that easily occurs in the existing pipe fittings during hot melt socket, and to provide an anti-low-temperature brittle cracking PPR pipe fitting that can adapt to the stress requirements during the hot melt socket of the pipe.

[0004] To achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0005] An anti-low-temperature brittle cracking PPR pipe fitting includes an insertion pipe portion and a reduced diameter portion provided between the two insertion pipe portions. The insertion pipe portion is the part that contacts the outer wall of the pipe during socket, and the reduced diameter portion is the part with an outer diameter larger than that of the insertion pipe; a glue receiving groove for accommodating the overflow glue of the hot melt welding is formed between the inner wall of the reduced diameter portion and the inner wall of the insertion pipe portion.

[0006] During the working process of the above scheme, first, the outer wall of the pipe to be connected and the inner wall of the pipe fitting are heated to a certain temperature by a heating die head, and then the pipe is quickly pushed into the pipe fitting, so that the inner wall of the socket pipe fitting contacts the pipe. The pipe is continuously pushed so that the end face of the pipe enters the glue receiving groove. At this time, the glue receiving groove starts to receive the overflow glue melted by the heat of the pipe end. Compared with not setting the glue receiving groove, setting the glue receiving groove can prevent the molten glue at this position from being insufficient and the pipe being forced to insert into the pipe fitting to generate greater internal stress, and finally avoid the problem of brittle cracking of the pipe fitting.

[0007] Preferably, the wall thickness of the reduced diameter portion is greater than that of the insertion pipe portion. Because the inner diameter of the reduced diameter portion is larger than the outer diameter of the pipe, the hoop stress formed by the medium is greater during use, so the required thickness is larger than that of the insertion pipe portion.

[0008] Preferably, the side surface where the diameter-changing part is connected to the inserting pipe part is a connecting inclined surface. The top end of the connecting inclined surface inclines towards the center of the diameter-changing part. The angle between the connecting inclined surface and the outer wall of the inserting pipe part is between 140° and 160°. The setting of the angle of this inclined surface ensures that the wall thickness at different positions of the pipe fitting reaches the design requirements of the circumferential stress.

[0009] Preferably, the axial lengths of the two inserting pipe parts at both ends of the diameter-changing part are equal, ensuring that the diameter-changing part is in the middle position of the entire pipe fitting, so that the stress at both ends of the diameter-changing part is uniform when the pipe fitting is hot-melt socketed.

[0010] Preferably, the inner side surface of the glue-receiving groove is a guiding inclined surface. The bottom end of the guiding inclined surface inclines away from the center of the diameter-changing part. Since the stress is greater when inserting closer to the normal socketing area and the transition area of the glue-receiving groove of the pipe fitting, the inclination angle of the guiding inclined surface is set to be greater than the inclination angle of the connecting inclined surface, so that the thickness near the guiding inclined surface at the bottom of the glue-receiving groove is larger to avoid cracking during socketing.

[0011] Preferably, the vertical center line of the glue-receiving groove in the axial direction coincides with the vertical center line of the axial length of the diameter-changing part, so that the inserting pipe parts on both sides of the glue-receiving groove have the same size of glue-receiving space, avoiding insufficient glue-receiving space at one end and affecting socketing.

[0012] Preferably, a stop block for limiting the pipe material is arranged in the glue-receiving groove. When the pipe material is pushed to the end face in contact with the stop block, the stop block starts to hinder the continuous advancement of the pipe material and provides a resistance feedback to prompt the operator that the pipe material has been socketed in place to prevent over-socketing.

[0013] Preferably, the stop block is located at the central position of the axial length of the glue-receiving groove. In addition, there is another setting which is a circular ring stop block that goes around the circumference of the pipe fitting at the center. The cuboid stop block has a smaller volume compared to the latter, saves materials and costs, occupies less space in the glue-receiving groove, and can leave a larger glue-receiving space.

[0014] Preferably, the axial length of the glue-receiving groove is two-thirds of the axial length of the diameter-changing part. When the axial length of the glue-receiving groove is too long or the axial length of the diameter-changing part is too short, the guiding inclined surface of the glue-receiving groove will face the guiding inclined surface of the diameter-changing part. At this time, the wall thickness at the guiding inclined surface will correspondingly decrease, and the stress that can be borne during socketing will decrease. When the axial length of the glue-receiving groove is too short or the axial length of the diameter-changing part is too long, it will cause the space of the glue-receiving slot to be too small to sufficiently accommodate the overflow glue or the allowance in the diameter-changing area to be too much, which will not only increase the requirements for the injection molding process conditions during manufacturing but also cause waste.

[0015] A pipe body connection assembly includes a pipe material, and when the pipe material is welded, the pipe is inserted into the pipe fitting.

[0016] Advantages of the present utility model: When the present utility model is in use, the hot-melt pipe enters the reduced-diameter part through the inserting part. The overflowing glue melted from the end face of the pipe starts to fill the glue-receiving groove. The glue-receiving groove has enough space to accommodate the overflowing glue, and the reduced-diameter part has enough wall thickness to withstand the stress during socket insertion. As the temperature drops, the pipe fitting, the pipe, and the overflowing glue start to solidify. The overflowing glue will not be squeezed between the pipe and the pipe fitting to generate stress. And due to the setting of the glue-receiving groove, there will be no stress caused by insufficient melting of the molten glue during forced socket insertion at the positions where the pipe and the pipe fitting are most prone to brittle cracking, thus solving the technical problem of preventing the pipe fitting from brittle cracking. At the same time, it can also prevent the inner diameter of the pipe from being reduced due to the overflowing glue. Brief Description of the Drawings

[0017] Figure 1 Structural schematic diagram of an anti-low-temperature brittle cracking pipe fitting according to Embodiment 1 of the present utility model;

[0018] Figure 2 Structural schematic diagram of an anti-low-temperature brittle cracking pipe fitting according to Embodiment 2 and Embodiment 3 of the present utility model;

[0019] Figure 3 Structural schematic diagram of an anti-low-temperature brittle cracking pipe fitting according to Embodiment 4 of the present utility model;

[0020] Figure 4 Structural schematic diagram of a pipe connection assembly according to Embodiment 5 of the present utility model. Detailed Embodiments

[0021] The following will describe the embodiments of the present utility model with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The present utility model can also be implemented or applied through different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present utility model. It should be understood that the preferred embodiments are only for illustrating the present utility model and not for limiting the protection scope of the present utility model.

[0022] It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present utility model in a schematic manner. Therefore, only the components related to the present utility model are shown in the drawings, rather than being drawn according to the number, shape, and size of the components during actual implementation. The type, quantity, and ratio of each component during actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0023] Embodiment 1

[0024] As Figure 1Embodiment 1 of a PPR pipe fitting for preventing low-temperature brittle cracking, including an insertion pipe part 1 and a reduced-diameter part 2 arranged between two insertion pipe parts 1. The insertion pipe part 1 is the part that contacts the outer wall of the pipe during socket insertion, and the reduced-diameter part 2 is the part with an increased diameter relative to the outer diameter of the insertion pipe. A glue-receiving groove 201 for storing the overflow glue from hot melt welding is formed between the inner wall of the reduced-diameter part 2 and the inner wall of the insertion pipe part 1.

[0025] Furthermore, the wall thickness of the reduced-diameter part 2 is greater than that of the insertion pipe part 1. Because the reduced-diameter part 2 has a glue-receiving groove 201 for storing the overflow glue and has greater stress during socket insertion, the required thickness is larger than that of the insertion pipe part 1.

[0026] Specifically, the wall thickness of the reduced-diameter part 2 is between 9 mm and 14 mm, and the wall thickness of the insertion pipe part 1 is between 8 mm and 12 mm. The wall thickness of the reduced-diameter part 2 is 1 mm larger than that of the insertion pipe part 1.

[0027] More specifically, the wall thickness of the insertion pipe part 1 can be 10.5 mm, and the wall thickness of the reduced-diameter part 2 is 11.5 mm.

[0028] In addition, process chamfers are provided at both ends of the insertion pipe part 1 to adapt to the flow of injection-molded melt during pipe fitting production.

[0029] During the working process of this embodiment, first, the outer wall of the pipe to be connected and the inner wall of the pipe fitting are heated to a certain temperature with a heating die head, then the pipe is quickly pushed into the pipe fitting so that the inner wall of the insertion pipe part 1 contacts the pipe, and the pipe is continuously pushed so that the end face of the pipe enters the glue-receiving groove 201. At this time, the glue-receiving groove 201 starts to receive the overflow glue melted by the heat at the end of the pipe.

[0030] Beneficial effects of this embodiment: When this embodiment works, the hot melt pipe enters the reduced-diameter part 2 through the insertion pipe part 1, and the overflow glue melted at the end face of the pipe starts to fill the glue-receiving groove 201. The glue-receiving groove 201 has enough space to accommodate the overflow glue, and the reduced-diameter part 2 has enough wall thickness to withstand the stress during socket insertion. As the temperature drops, the pipe fitting, the pipe, and the overflow glue start to solidify. Since there is no extrusion stress between the end of the pipe and the bottom of the socket insertion area of the pipe fitting, the technical problem of brittle cracking of the pipe fitting is avoided, and at the same time, the reduction of the inner diameter of the pipe caused by the overflow glue is also avoided.

[0031] Embodiment 2

[0032] As Figure 2 Embodiment 2 of a PPR pipe fitting for preventing low-temperature brittle cracking, including an insertion pipe part 1 and a reduced-diameter part 2 arranged between two insertion pipe parts 1. The insertion pipe part 1 is the part that contacts the outer wall of the pipe 3 during socket insertion, and the reduced-diameter part 2 is the part with an increased diameter relative to the outer diameter of the insertion pipe. A glue-receiving groove 201 for storing the overflow glue from hot melt welding is formed between the inner wall of the reduced-diameter part 2 and the inner wall of the insertion pipe part 1.

[0033] Further, the side surface where the diameter-changing part 2 is connected to the inserting pipe part 1 is a connecting inclined surface 202. The top end of the connecting inclined surface 202 inclines towards the center direction of the diameter-changing part 2. The angle between the connecting inclined surface 202 and the outer wall of the inserting pipe part 1 is between 140° and 160°. The angle setting of this inclined surface ensures that the wall thickness at different positions of the pipe fitting reaches the design requirements of the hoop stress.

[0034] Further, the inner side surface of the glue-receiving groove 201 is a guiding inclined surface 2011. The bottom end of the guiding inclined surface 2011 inclines away from the center direction of the diameter-changing part 2. Since the stress during socket insertion is greater closer to the center of the glue-receiving groove 201, the inclination angle of the guiding inclined surface 2011 is set to be greater than the inclination angle of the connecting inclined surface 202, so that there is a relatively large thickness near the guiding inclined surface 201 at the bottom of the glue-receiving groove 201 to avoid insufficient pressure bearing due to the reduction of the wall thickness after socket insertion. The angle between the guiding inclined surface 2011 and the inner wall of the inserting pipe part 1 should be between 155° and 165°. Chamfers are provided at the positions where both ends of the guiding inclined surface 2011 are connected to the inner wall of the inserting pipe part 1 and the bottom of the glue-receiving groove 201 to adapt to the flow of the overflowing molten glue.

[0035] Specifically, it is sufficient that the inclination angle of the guiding inclined surface 2011 is 10° greater than the inclination angle of the connecting inclined surface 202. The angle between the connecting inclined surface 202 and the outer wall of the inserting pipe part 1 can be set to 147°, and the angle between the guiding inclined surface 2011 and the inner wall of the inserting pipe part 1 can be set to 157°.

[0036] During the working process of this embodiment, first, the outer wall of the pipe 3 to be connected and the inner wall of the pipe fitting are heated to a certain temperature by a heating die head, and then the pipe 3 is quickly pushed into the pipe fitting so that the inner wall of the inserting pipe part 1 contacts the pipe 3. Then, the pipe 3 is continuously pushed so that the end surface of the pipe 3 enters the glue-receiving groove 201. At this time, the glue-receiving groove 201 starts to receive the overflowing glue melted by the heat at the end of the pipe 3.

[0037] The beneficial effects of this embodiment compared with Embodiment 1: By setting the angle between the guiding inclined surface 2011 and the inner wall of the inserting pipe part 1 to be greater than the connection angle between the connecting inclined surface 202 and the outer wall of the inserting pipe part 1, the diameter-changing part 2 can effectively increase the wall thickness at the position where the guiding inclined surface 2011 intersects with the bottom of the glue-receiving groove 201 without increasing the overall wall thickness, so as to adapt to the high-stress conditions in this area, and the anti-low-temperature brittle cracking effect is better.

[0038] Embodiment 3

[0039] As Figure 2 shown in Embodiment 3 of a PPR pipe fitting for preventing low-temperature brittle cracking, it includes an inserting pipe part 1 and a diameter-changing part 2 provided between two inserting pipe parts 1. The inserting pipe part 1 is the part that contacts the outer wall of the pipe 3 during socket insertion, and the diameter-changing part 2 is the part with an increased outer diameter relative to the inserting pipe. A glue-receiving groove 201 for storing the overflowing glue from the hot melt welding is formed between the inner wall of the diameter-changing part 2 and the inner wall of the inserting pipe part 1.

[0040] Furthermore, the axial lengths of the two insertion parts 1 at both ends of the diameter-changing part 2 are equal, ensuring that the diameter-changing part 2 is located in the middle of the entire pipe fitting, so that the stresses at both ends of the diameter-changing part 2 are uniform during hot-melt socket welding of the pipe fitting.

[0041] Furthermore, the vertical center line of the glue-receiving groove 201 in the axial direction coincides with the vertical center line of the axial length of the diameter-changing part 2, so that the insertion parts 1 on both sides of the glue-receiving groove 201 have the same-sized glue-receiving space, avoiding insufficient glue-receiving space at one end and protruding molten glue affecting the through diameter.

[0042] Furthermore, the axial length of the glue-receiving groove 201 is two-thirds of the axial length of the diameter-changing part 2. When the axial length of the glue-receiving groove 201 is too long or the axial length of the diameter-changing part 2 is too short, the guiding inclined surface 2011 of the glue-receiving groove 201 will face the guiding inclined surface 2011 of the diameter-changing part 2. At this time, the wall thickness at the guiding inclined surface 2011 will correspondingly decrease, and the stress that can be borne during socket welding will decrease. When the axial length of the glue-receiving groove 201 is too short or the axial length of the diameter-changing part 2 is too long, it will cause the glue-receiving slot space to be too small to sufficiently accommodate the overflow glue, or the allowance in the diameter-changing area to be too large, resulting in not only increasing the requirements for the injection molding process conditions during manufacturing but also causing waste.

[0043] Specifically, the radial height of the glue-receiving groove 201 is between 2 mm and 4 mm, the axial length is between 32 mm and 36 mm, and the axial length of the diameter-changing part 2 is between 48 mm and 54 mm. Correspondingly, when the axial length of the glue-receiving groove 201 is 32 mm, the axial length of the diameter-changing part 2 is set to 48 mm; when the axial length of the glue-receiving groove 201 is 34 mm, the axial length of the diameter-changing part 2 is set to 50 mm. When the axial length of the diameter-changing part 2 is too small, the shaft section of the diameter-changing part 2 cannot appropriately extend beyond the glue-receiving groove 201 by a certain distance, and it is impossible to increase the wall thickness above the guiding inclined surface 2011 of the glue-receiving groove 201, making it difficult to adapt to the high-stress conditions during welding at the guiding inclined surface 2011. When the axial length of the diameter-changing part 2 is too large, the diameter-changing part 2 will extend to the insertion part 1, causing the wall thickness of the insertion part 1 to increase and not meet the requirements of the injection molding process; the axial length of the insertion part 1 is between 25 and 30 mm. When the axial length of the diameter-changing part 2 is set to 48 mm, the axial length of the insertion part 1 is set to 26 mm; when the axial length of the diameter-changing part 2 is set to 50 mm, the axial length of the insertion part 1 is set to 50 mm, so as to ensure that the pipe 3 and the pipe fitting have sufficient welding and fitting length, and thus the welding is more firm.

[0044] The beneficial effects of this embodiment compared with Embodiment 2: By reasonably arranging the position and size of the glue-receiving groove 201 in the diameter-changing part 2, the space of the entire glue-receiving groove 201 is sufficient to accommodate the overflow glue during hot-melt socket welding, effectively avoiding the situation that the overflow glue overflows into the inner wall of the pipe 3 due to insufficient space, reducing the inner diameter of the pipe 3.

[0045] Embodiment 4

[0046] Example 4 of a PPR pipe fitting for preventing low-temperature brittle cracking, as Figure 3 shown, includes an insertion pipe portion 1 and a reduced-diameter portion 2 disposed between two insertion pipe portions 1. The insertion pipe portion 1 is the part that contacts the outer wall of the pipe 3 during socket insertion, and the reduced-diameter portion 2 is the part with an increased diameter relative to the outer diameter of the insertion pipe. A glue-receiving groove 201 for storing the overflow glue from hot melt welding is formed between the inner wall of the reduced-diameter portion 2 and the inner wall of the insertion pipe portion 1.

[0047] Among them, a stopper 2012 for limiting the pipe 3 is provided in the glue-receiving groove 201. When the end of the pipe 3 is pushed to the middle of the glue-receiving groove 201, the stopper 2012 starts to hinder the continuous advancement of the pipe 3 and provides a resistance feedback to prompt the operator that the pipe 3 has been inserted in place to prevent over-insertion.

[0048] Further, the stopper 2012 is a cuboid located at the center of the axial length of the glue-receiving groove 201. In addition, there is another setting which is a circular ring stopper 2012 that goes around the circumference of the pipe fitting at the center. The cuboid stopper 2012 has a smaller volume and occupies less space in the glue-receiving groove 201 compared to the latter, leaving a larger glue-receiving space and having a better anti-cracking effect. The length of the cuboid stopper 2012 should be between 5 mm and 6 mm, and the width should be between 4 mm and 5 mm. Two stoppers 2012 are provided at the center of the glue-receiving groove 201, and the two stoppers 2012 are on a straight line of the pipe fitting diameter.

[0049] The beneficial effect of this embodiment compared to Embodiment 1: By providing two stoppers 2012, the pipe 3 is limited during socket insertion to prevent the pipes 3 entering from both ends of the insertion pipe portion 1 from squeezing each other to produce too much overflow glue, and the protruding melt glue affects the through diameter.

[0050] Embodiment 5

[0051] As Figure 4 shown, a pipe connection assembly includes a pipe 3 and the anti-cracking PPR pipe fitting of any of the above embodiments. During the working process of this embodiment, the pipe 3 is inserted into the pipe fitting. When the temperature cools to room temperature, the pipe 3 adheres to the insertion pipe portion 1 of the pipe fitting.

[0052] Further, the axial lengths of the two insertion pipe portions 1 at both ends of the reduced-diameter portion 2 are equal, ensuring that the reduced-diameter portion 2 is in the middle position of the entire pipe fitting, so that the stress at both ends of the reduced-diameter portion 2 is uniform during hot melt socket insertion.

[0053] The remaining technical features and working principles of this embodiment are the same as those of Embodiment 1 or Embodiment 2.

Claims

1. A PPR pipe fitting resistant to low-temperature brittle cracking, characterized in that, It includes an insertion tube part (1) and a diameter-changing part arranged between two insertion tube parts (1). The insertion tube part (1) is the part that contacts the outer wall of the pipe (3) during socket insertion, and the diameter-changing part is the part with an increased outer diameter relative to the insertion tube; a glue-receiving groove (201) for accommodating the overflow glue of hot melt welding is formed between the inner wall of the diameter-changing part and the inner wall of the insertion tube part (1).

2. The anti-low temperature brittle cracking PPR pipe fitting according to claim 1, wherein, The wall thickness of the diameter-changing part (2) is greater than the wall thickness of the insertion tube part (1).

3. The anti-low-temperature brittle cracking PPR pipe fitting according to claim 2, characterized in that, The side surface where the diameter-changing part (2) is connected to the insertion tube part (1) is a connecting inclined surface (202), and the top end of the connecting inclined surface (202) inclines towards the center direction of the diameter-changing part (2).

4. The anti-low-temperature brittle cracking PPR pipe fitting according to claim 3, characterized in that, The lengths of the two insertion tube parts (1) at both ends of the diameter-changing part (2) in the axial direction are equal.

5. The PPR pipe fitting for preventing low-temperature brittle cracking according to claim 1, characterized in that, The inner side surface of the glue-receiving groove (201) is a guiding inclined surface (2011), and the bottom end of the guiding inclined surface (2011) inclines away from the center direction of the diameter-changing part (2).

6. The anti-low-temperature brittle cracking PPR pipe fitting according to claim 5, characterized in that, The vertical center line of the glue-receiving groove (201) in the axial direction coincides with the vertical center line of the axial length of the diameter-changing part (2).

7. The anti-low temperature brittle cracking PPR pipe fitting according to claim 6, characterized in that, A stop block (2012) for limiting the pipe (3) is arranged in the glue-receiving groove (201).

8. The anti-low temperature brittle cracking PPR pipe fitting according to claim 7, characterized in that, The stop block (2012) is a cuboid located at the center of the axial length of the glue-receiving groove (201).

9. The anti-low-temperature brittle cracking PPR pipe fitting according to claim 1, characterized in that, The axial length of the glue-receiving groove (201) is two-thirds of the axial length of the diameter-changing part (2).

10. A pipe connection assembly, comprising a pipe (3), characterized in that: It also includes a PPR pipe fitting for preventing low-temperature brittle cracking according to any one of claims 1-9. When the pipe (3) is welded, the pipe is inserted into the pipe fitting.

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