A high-pressure-resistant socket brass pipe fitting by clamping and a preparation method thereof

Abstract

The application discloses a kind of high-pressure socket red copper pipe fittings of clamping and its preparation method, comprising: main body, respectively in the socket of the both ends of main body and respectively in the two bulges of the outer end of two socket, the main body is bent and is arranged, the wall thickness H1 of the bulge is greater than the wall thickness H of the main body, the wall thickness H2 of the socket is greater than the wall thickness H of the main body.The thickness of the socket of the application and the thickness of the bulge are greater than the thickness of the main body, after clamping and pressing with pipeline, sealing performance is good, pressure resistance is strong, improve service life, preparation method can increase the thickness of red copper pipe fittings, and production efficiency is high.

Description

Technical Field

[0001] This invention relates to the technical field of copper pipe fitting processing, and in particular to a press-fit high-pressure-resistant copper pipe fitting and its preparation method. Background Technology

[0002] Press-fit copper pipe fittings connect the socket with a sealing ring to the pipe. The sealing ring is installed inside the bulge at the end of the socket. The pipe is pressed with a special tool to achieve sealing and fixing. They are characterized by pull-out resistance, rotation resistance, simple and convenient installation, and shock resistance.

[0003] For press-fit copper pipe fittings with bulges, the bulge area will be filled with a sealing ring, and the socket will be connected to the pipe, so the outer diameter of both the bulge and the socket needs to be enlarged. Using existing cold extrusion forming processes, the socket and bulge of the pipe fitting are often deformed, wrinkled, or cracked due to compression, making it impossible to achieve flaring.

[0004] Therefore, the industry mainly adopts the water-expansion forming flaring process. The water-expansion forming process is: mandrel sealing → water-expansion forming → flat end → bulging. After water-expansion forming, the diameter of the socket and bulging part of the pipe fitting increases, and its wall thickness is thinner than that of the main body of the pipe fitting. Since the socket and bulging parts are the main connection parts, if their thickness is too small, loosening will occur after the sealing ring is installed, resulting in poor sealing effect with the pipeline. In fact, when the pipeline pressure suddenly increases, the pipe fitting may even break at the clamping point. Therefore, the industry increases the overall thickness of the pipe fitting raw materials to ensure that the wall thickness of the socket and bulging parts meets its pressure resistance requirements, but this also increases the wall thickness of the main body, resulting in high raw material costs. In addition, the water-expansion process requires water pump pressure forming, and the production cycle of the water-expansion forming process is nearly 30 seconds per piece, resulting in low production efficiency. Summary of the Invention

[0005] To address the aforementioned problems with existing copper pipe fittings, this paper aims to provide a press-fit high-pressure-resistant socket copper pipe fitting and its manufacturing method. The thickness of the socket and the thickness of the bulge in the provided copper pipe fitting are greater than the thickness of the main body. After being press-fitted with the pipeline, it has good sealing performance, strong pressure resistance, and improved service life. The provided manufacturing method can increase the thickness of the copper pipe fitting and has high production efficiency.

[0006] The specific technical solution is as follows:

[0007] A press-fit high-pressure resistant copper pipe fitting includes: a main body, sockets respectively disposed at both ends of the main body, and two bulges respectively disposed on the outer ends of the two sockets. The main body is bent, and the wall thickness H1 of the bulges is greater than the wall thickness H of the main body, and the wall thickness H2 of the sockets is greater than the wall thickness H of the main body.

[0008] In the aforementioned press-fit high-pressure-resistant copper pipe fitting, each of the bulges includes a first inclined section and a bent section connected to each other. The first inclined section is connected to the socket, the first inclined section is inclined to the outside of the socket, and the bent section is bent to the inside of the socket.

[0009] A method for preparing a press-fit high-pressure-resistant copper pipe fitting, wherein the method for producing the press-fit high-pressure-resistant copper pipe fitting described in any one of the above-mentioned methods uses a tapered flaring mechanism and a bulging bending mechanism.

[0010] The tapered flaring mechanism includes a tapered flaring mold and two tapered mandrels, wherein the tapered flaring mold has a tapered forming cavity.

[0011] The bulge bending mechanism includes: a bulge bending mold and two bulge forming assemblies, wherein the bulge bending mold has a bulge bending cavity.

[0012] The preparation method includes:

[0013] Step S1: Use a bending machine to bend the straight pipe into a bent pipe;

[0014] Step S2: Place the bent tube into the tapered forming cavity, the tapered forming cavity positions the middle part of the bent tube, and the two tapered mandrels respectively press the two ends of the bent tube so that both ends of the bent tube form a tapered forming part and a flared part, and the bent tube forms a tapered bent tube;

[0015] Step S3: Place the tapered bend into the bulge bending cavity. The tapered bending cavity positions the middle part of the tapered bend. The middle part of the tapered bend forms the main body. The two bulge forming groups respectively squeeze the two ends of the tapered bend. The tapered forming part forms the socket, and the flared part forms the bulge, thus realizing the finished product processing.

[0016] The above-mentioned method for preparing press-fit high pressure-resistant copper pipe fittings includes a tapered forming cavity comprising: a first positioning part, tapered forming parts located at both ends of the first positioning part, and tapered flared parts located at both ends of the two tapered forming parts.

[0017] In step S2, the first positioning part positions the middle part of the bent tube, and the tapered mandrel presses the end of the bent tube so that the outer wall of the end of the bent tube abuts against the inner wall of the tapered forming part and the inner wall of the tapered flaring part, and the end of the bent tube forms the tapered forming part and the flaring part.

[0018] The bulge bending cavity includes: a second positioning part, a socket shaping part located at both ends of the second positioning part, and a bulge part located at both ends of the two socket shaping parts.

[0019] In step S3, the second positioning part positions the middle part of the tapered bend, and the middle part of the tapered bend forms the main body. The bulge forming group extrudes the tapered forming part and the flared part. The outer wall of the tapered forming part abuts against the inner wall of the socket shaping part to form the socket. The outer wall of the flared part abuts against the inner wall of the bulge part to form the bulge.

[0020] The above-mentioned method for preparing press-fit high-pressure-resistant copper pipe fittings, wherein the flared section includes a second inclined section and a straight section connected to each other;

[0021] In step S3, the tapered bend is placed in the bulging bending cavity, the second positioning part positions the middle part of the tapered bend, the middle part of the tapered bend forms the main body, the bulging forming group extrudes the tapered forming part and the flared part, the tapered forming part forms the socket, the second inclined section forms the first inclined section, and the straight section forms the bending section, thus realizing the finished product processing.

[0022] The above-mentioned method for preparing high pressure-resistant copper pipe fittings with press-fit type sockets, wherein the bulging forming assembly includes: a rolled edge sleeve and a bulging core rod, the rolled edge sleeve is a hollow structure with open ends, one end of the rolled edge sleeve has an arc-shaped forming groove connected to its hollow portion, and the bulging core rod penetrates through the hollow portion of the rolled edge sleeve;

[0023] In step S3, the tapered bend is placed in the bulging bending cavity, the second positioning part positions the middle part of the tapered bend, the middle part of the tapered bend forms the main body, the bulging core extrudes the tapered forming part, the rolled edge sleeve extrudes the straight section, the tapered forming part forms the socket, the second inclined section forms the first inclined section, the straight section extends into the arc-shaped forming groove, bends and abuts against the bulging core to form the bent section, thus realizing the finished product processing.

[0024] The above-mentioned method for preparing press-fit high-pressure-resistant copper pipe fittings, wherein the tapered mandrel includes a tapered portion and a first mandrel body connected to each other;

[0025] In step S2, the tapered mandrel presses the end of the bent tube so that the portion of the tapered part pressing the bent tube forms the tapered forming part, and the portion of the first mandrel body pressing the bent tube forms the flared part;

[0026] The bulging core rod includes a cylindrical part and a second core rod body that are connected to each other;

[0027] In step S3, the rolled edge sleeve and the bulging mandrel squeeze the end of the tapered bend so that the cylindrical part squeezes the tapered forming part to form the socket. The rolled edge sleeve squeezes the straight cylindrical section in the flared part. The straight cylindrical section extends into the arc-shaped forming groove, bends, and abuts against the outer wall of the second mandrel body to form the curved section.

[0028] The above-mentioned method for preparing press-fit high-pressure-resistant copper pipe fittings includes, before step S1, the straight pipe undergoes semi-finished annealing treatment. When the wall thickness H of the straight pipe is in the range of 1 to 1.4 mm, the annealing temperature is 480-510℃ and the annealing time is 30 to 40 min. When the wall thickness H of the straight pipe is ≥1.5 mm, the annealing temperature is 480-510℃ and the annealing time is 40 to 55 min.

[0029] After step S3, the finished product undergoes a finished product annealing process, using a progressive processing method;

[0030] The progressive processing method includes:

[0031] Step A1: Annealing temperature of the inner liner of the heating furnace is 380-400℃, and the outer liner of the heating furnace is set at 430-450℃ for 15-20 minutes.

[0032] Step A2: Annealing temperature of the inner liner of the heating furnace is 380-400℃, and the outer liner of the heating furnace is set at 450-470℃ for 25-35 minutes.

[0033] Step A3: The annealing temperature of the inner liner of the heating furnace is 380-400℃, the temperature of the outer liner of the heating furnace is set to 480-510℃, and the heating time is 85-100 minutes.

[0034] The above-mentioned method for preparing press-fit high pressure-resistant copper pipe fittings includes, before the semi-finished product annealing treatment, the straight pipe is first cleaned by vibrating, polishing, cleaning to remove copper shavings and oil stains, and then drying.

[0035] The tapered bend that has been processed and formed is then cleaned a second time. The tapered bend is vibrated, polished, and cleaned to remove copper shavings and oil stains, and then dried.

[0036] The finished product is then subjected to a third cleaning process, including vibration, polishing, cleaning, and drying.

[0037] The second cleaning process involves washing with dried corncob fragments.

[0038] The above-mentioned method for preparing press-fit high-pressure-resistant copper pipe fittings includes, wherein the tapered bend is finished by a flat-end machine after the second cleaning.

[0039] After the finished product undergoes the finished product annealing treatment, a sealing ring is inserted into the bulge, and the finished product is inspected and packaged.

[0040] The positive effects of the above technical solution compared with the existing technology are:

[0041] The thickness of the socket and the thickness of the bulge in this invention are greater than the thickness of the main body, resulting in good sealing performance, strong pressure resistance, and improved service life after connection with the pipe.

[0042] The preparation method of the present invention adopts a step-by-step segmented flaring process, which first tapers and then flares out and bulges. Under the condition that the product is not squeezed and deformed, it can achieve the following: for the same blanking size, the wall thickness of the socket and the bulge is greater than that of the water-expanded flaring process, which has stronger pressure resistance and better sealing performance after the sealing ring is assembled. At the same time, the processing efficiency is greatly improved compared with water expansion molding.

[0043] The preparation method of the present invention can increase the thickness of the socket and the thickness of the bulge, and uses a tapered flaring mechanism and a bulge bending mechanism, which is more efficient than the additional form required for water expansion molding pumps.

[0044] This invention employs a multi-stage stepped annealing process to achieve a Rockwell hardness range of 60-70R15T for press-fit high-pressure-resistant copper pipe fittings. Hardness exceeding 70HR15T can cause burrs during press-fit installation. Furthermore, excessive hardness after press-fit assembly can lead to springback and leakage. Hardness below 60HR15T reduces the pipe fitting's pressure resistance, making it prone to rupture under sudden pressure increases. This invention significantly improves the pressure resistance of the pipe fittings while ensuring good extensibility during molding.

[0045] This invention employs a multi-stage cleaning process and corn cob cleaning and polishing to achieve a smooth product surface free from defects such as rough streaks and red spots.

[0046] The manufacturing method of this invention solves the problems of bulging and thinning of the socket wall caused by the water-expansion flaring process. After the pipe fitting of this invention is press-fitted to the pipeline, it will not detach until the strength test pressure reaches 8 MPa to 11 MPa, demonstrating good pressure resistance. In contrast, the water-expansion molding process causes it to detach when the strength test pressure reaches 5 MPa to 6 MPa, resulting in poor pressure resistance. Attached Figure Description

[0047] Figure 1 This is a structural schematic diagram of a press-fit high-pressure-resistant copper pipe fitting according to the present invention;

[0048] Figure 2 This is a schematic diagram of the tapered flaring mold and tapered mandrel in the preparation method of a press-fit high-pressure-resistant copper pipe fitting of the present invention;

[0049] Figure 3 This is a schematic diagram of the tapered bend in the preparation method of a press-fit high-pressure-resistant copper pipe fitting of the present invention;

[0050] Figure 4 This is a schematic diagram of step S2 in the preparation method of a press-fit high-pressure-resistant copper pipe fitting of the present invention;

[0051] Figure 5 This invention relates to a method for preparing a press-fit high-pressure-resistant copper pipe fitting. Figure 4 Enlarged view of point A in the middle;

[0052] Figure 6 This is a schematic diagram of the bulging bending mold and bulging forming assembly in the preparation method of a press-fit high-pressure-resistant copper pipe fitting of the present invention;

[0053] Figure 7 This is a schematic diagram of step S3 in the preparation method of a press-fit high pressure-resistant copper pipe fitting of the present invention;

[0054] Figure 8 This invention relates to a method for preparing a press-fit high-pressure-resistant copper pipe fitting. Figure 7 Enlarged view at point B in the middle;

[0055] In the attached diagram: 1. Main body; 2. Socket; 3. Bulge; 31. First inclined section; 32. Bending section; 41. Tapered flaring mold; 42. Tapered mandrel; 421. Conical part; 422. First mandrel main body; 43. Tapered forming cavity; 431. First positioning part; 432. Tapered forming part; 433. Tapered flaring part; 51. Bulge bending mold; 52. Bulge forming assembly; 521. Edge rolled sleeve; 522. Bulge mandrel; 5221. Cylindrical part; 5222. Second mandrel main body; 523. Arc-shaped forming groove; 53. Bulge bending cavity; 531. Second positioning part; 532. Socket shaping part; 533. Bulge part; 6. Tapered bend; 61. Tapered forming part; 62. Flaring part; 621. Second inclined section; 622. Straight cylindrical section. Detailed Implementation

[0056] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0057] Figure 1 This is a schematic diagram of the overall structure of a press-fit high-pressure-resistant copper pipe fitting and its preparation method according to the present invention. Figure 1As shown in Figure E, a preferred embodiment of a press-fit high-pressure-resistant copper pipe fitting includes: a main body 1, sockets 2 respectively disposed at both ends of the main body 1, and two bulges 3 respectively disposed on the outer ends of the two sockets 2. The main body 1 is bent, the wall thickness H1 of the bulges 3 is greater than the wall thickness H of the main body 1, and the wall thickness H2 of the sockets 2 is greater than the wall thickness H of the main body 1.

[0058] Furthermore, as a preferred embodiment, each bulge 3 includes a first inclined section 31 and a curved section 32 connected to each other. The first inclined section 31 is connected to the socket 2, the first inclined section 31 is inclined to the outside of the socket 2, and the curved section 32 is curved to the inside of the socket 2.

[0059] Preferably, H1-H = 0.03cm to 0.25cm and H2-H = 0.03mm to 0.25mm.

[0060] Preferably, the outer diameter D of the main body 1 is in the range of: 12mm≤D<28mm, H ranges from 1.0mm to 1.3mm, H1 ranges from 1.35mm to 1.7mm, and H2 ranges from 1.35mm to 1.7mm; the outer diameter D of the main body is in the range of: 28mm≤D<42mm, H ranges from 1.1mm to 1.38mm, H1 ranges from 1.35mm to 1.7mm, and H2 ranges from 1.35mm to 1.7mm; the outer diameter D of the main body is in the range of: D≥42mm, H ranges from 1.2mm to 1.5mm, H1 ranges from 1.35mm to 1.7mm, and H2 ranges from 1.35mm to 1.7mm.

[0061] As a preferred option, the Rockwell hardness of press-fit high-pressure-resistant copper pipe fittings is 60-70HR15T.

[0062] This invention controls the Rockwell hardness range of copper pipe fittings to 60-70HR15T. Hardness higher than 70HR15T will cause burrs to appear during the installation of press-fit products, while hardness lower than 60HR15T will lead to a decrease in the strength and pressure of the pipe fittings.

[0063] Preferably, when the D range of the main body 1 is 12mm≤D<22mm, the strength pressure of the press-fit high-pressure-resistant copper pipe fitting is 8MPa-11MPa; when the D range of the main body is 22mm≤D<35mm, the strength pressure of the press-fit high-pressure-resistant copper pipe fitting is 7MPa-10.5MPa; when the D range of the main body is 35mm≤D<54mm, the strength pressure of the press-fit high-pressure-resistant copper pipe fitting is 6MPa-8MPa; when the D range of the main body is D≥54mm, the strength pressure of the press-fit high-pressure-resistant copper pipe fitting is 5MPa-7.5MPa.

[0064] The present invention also discloses a method for preparing a press-fit high pressure-resistant copper pipe fitting, which is used to produce the above-mentioned press-fit high pressure-resistant copper pipe fitting.

[0065] The manufacturing method uses a tapered flaring mechanism and a bulging bending mechanism;

[0066] The tapered flaring mechanism includes: a tapered flaring mold 41 and two tapered mandrels 42, wherein the tapered flaring mold 41 has a tapered forming cavity 43;

[0067] The bulge bending mechanism includes a bulge bending mold 51 and two bulge forming groups 52, wherein the bulge bending mold 51 has a bulge bending cavity 53.

[0068] Furthermore, as a preferred embodiment, the preparation method includes:

[0069] Step S1: Use a bending machine to bend the straight pipe into a bent pipe;

[0070] Step S2: Place the bent tube into the tapered forming cavity 43. The tapered forming cavity 43 positions the middle part of the bent tube. The two tapered mandrels 42 press the two ends of the bent tube respectively so that both ends of the bent tube form a tapered forming part 61 and a flared part 62, and the bent tube forms a tapered bent tube 6.

[0071] Step S3: Place the tapered bend 6 into the bulge bending cavity 53. The bulge bending cavity 53 positions the middle part of the tapered bend 6. The middle part of the tapered bend 6 forms the main body 1. The two bulge forming groups 52 respectively squeeze the two ends of the tapered bend 6. The tapered forming part 61 forms the socket 2, and the flared part 62 forms the bulge 3, thus realizing the finished product processing.

[0072] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention.

[0073] In addition to the above, the present invention also has the following embodiments:

[0074] In further embodiments of the present invention, please continue to refer to Figure 1 As shown in Figure E, the tapered forming cavity 43 includes: a first positioning part 431, tapered forming parts 432 located at both ends of the first positioning part 431, and tapered flared parts 433 located at both ends of the two tapered forming parts 432.

[0075] In step S2, the first positioning part 431 positions the middle part of the bend, and the tapered mandrel 42 presses the end of the bend so that the outer wall of the end of the bend abuts against the inner wall of the tapered forming part 432 and the inner wall of the tapered flaring part 433, and the end of the bend forms a tapered forming part 61 and a flaring part 62.

[0076] In a further embodiment of the present invention, the bulge bending cavity 53 includes: a second positioning part 531, a socket shaping part 532 located at both ends of the second positioning part 531, and a bulge part 533 located at both ends of the two socket shaping parts 532.

[0077] In step S3, the second positioning part 531 positions the middle part of the tapered bend 6, and the middle part of the tapered bend 6 forms the main body 1. The bulge forming group 52 extrudes the tapered forming part 61 and the flared part 62. The outer wall of the tapered forming part 61 abuts against the inner wall of the socket shaping part 532 to form the socket 2. The outer wall of the flared part 62 abuts against the inner wall of the bulge part 533 to form the bulge 3.

[0078] In a further embodiment of the present invention, the flared portion 62 includes a second inclined section 621 and a straight section 622 connected to each other;

[0079] In step S3, the tapered bend 6 is placed in the bulging bending cavity 53, the second positioning part 531 positions the middle part of the tapered bend 6, the middle part of the tapered bend 6 forms the main body 1, the bulging forming group 52 extrudes the tapered forming part 61 and the flared part 62, the tapered forming part 61 forms the socket 2, the second inclined section 621 forms the first inclined section 31, and the straight section 622 forms the bending section 32, thus realizing the finished product processing.

[0080] In a further embodiment of the present invention, the bulge forming assembly 52 includes: a rolled edge sleeve 521 and a bulge core rod 522. The rolled edge sleeve 521 is a hollow structure with open ends. One end of the rolled edge sleeve 521 has an arc-shaped forming groove 523 that communicates with its hollow portion. The bulge core rod 522 penetrates the hollow portion of the rolled edge sleeve 521.

[0081] In step S3, the tapered bend 6 is placed in the bulging bending cavity 53. The second positioning part 531 positions the middle part of the tapered bend 6, forming the main body 1 in the middle part of the tapered bend 6. The bulging core rod 522 extrudes the tapered forming part 61, and the rolled edge sleeve 521 extrudes the straight cylindrical section 622. The tapered forming part 61 forms the socket 2, and the second inclined section 621 forms the first inclined section 31. The straight cylindrical section 622 extends into the arc-shaped forming groove 523, bends, and abuts against the bulging core rod 522 to form the bent section 32, thus realizing the finished product processing.

[0082] In a further embodiment of the present invention, the tapered mandrel 42 includes a tapered portion 421 and a first mandrel body 422 connected to each other;

[0083] In step S2, the tapered mandrel 42 presses the end of the bent tube so that the portion of the tapered part 421 pressing the bent tube forms a tapered forming part 61, and the portion of the first mandrel body 422 pressing the bent tube forms a flared part 62.

[0084] In a further embodiment of the present invention, the bulging core rod 522 includes a cylindrical part 5221 and a second core rod body 5222 that are connected to each other;

[0085] In step S3, the hem sleeve 521 and the bulging core rod 522 press the end of the tapered bend 6 so that the cylindrical part 5221 presses the tapered forming part 61 to form the socket 2, and the hem sleeve 521 presses the straight cylindrical section 622 in the flared part 62. The straight cylindrical section 622 extends into the arc-shaped forming groove 523, bends and abuts against the outer wall of the second core rod body 5222 to form the bent section 32.

[0086] A method for preparing a press-fit high-pressure-resistant copper pipe fitting includes the following detailed steps:

[0087] 1) Material cutting: The raw material for cutting is straight pipe TP2 H80. The cutting dimensions are: outer diameter D × wall thickness H × length L.

[0088] 2) First cleaning: The straight pipe is cleaned by vibration polishing to remove copper shavings and oil stains and then dried;

[0089] 3) Annealing treatment of semi-finished products: For products with wall thickness H ranging from 1 to 1.4 mm, the annealing temperature is 480-510℃ and the annealing time is 30-40 min; for products with wall thickness H ≥ 1.5 mm, the annealing temperature is 480-510℃ and the annealing time is 40-55 min.

[0090] 4) Bending: Using a bending machine to bend the pipe to form a bent pipe;

[0091] 5) Taper forming: A hydraulic press with tapered die holes and a tapered flaring mechanism are used to process both ends of the bend to form a tapered bend;

[0092] 6) Second cleaning: The conical bend is cleaned by a vibratory polishing and cleaning line to remove copper shavings and oil stains and then dried.

[0093] 7) Finishing: Use a finishing machine to finish the edges until the weight meets the requirements;

[0094] 8) Flaring and Bulging: A bulging bending mechanism is used to process tapered bends to form copper pipe fittings;

[0095] 9) Inspection: Inspect the dimensions of the copper pipe fittings to ensure that each process meets the requirements;

[0096] 10) Third cleaning: Vibrate, polish, clean and dry the inspected copper fittings;

[0097] 11) Finished product annealing treatment: The annealing temperature of the inner liner of the heating furnace is 380-400℃, and the annealing time is stepped heating progression: First stage: the outer liner of the heating furnace is set at 430-450℃, and the heating time is 15-20min; Second stage: the outer liner of the heating furnace is set at 450-470℃, and the heating time is 25-35min; Third stage: the outer liner of the heating furnace is set at 480-510℃, and the heating time is 85-100min.

[0098] 12) Install sealing rings: Fill the bulges of the copper pipe fittings with the required O-rings for sealing;

[0099] 13) Inspect the packaging.

[0100] The thickness of the socket and the thickness of the bulge in this invention are greater than the thickness of the main body, resulting in good sealing performance, strong pressure resistance, and improved service life after connection with the pipe.

[0101] The preparation method of the present invention adopts a step-by-step segmented flaring process, which first tapers and then flares out and bulges. Under the condition that the product is not squeezed and deformed, it can achieve the following: for the same blanking size, the wall thickness of the socket and the bulge is greater than that of the water-expanded flaring process, which has stronger pressure resistance and better sealing performance after the sealing ring is assembled. At the same time, the processing efficiency is greatly improved compared with water expansion molding.

[0102] The preparation method of the present invention can increase the thickness of the socket and the thickness of the bulge, and uses a tapered flaring mechanism and a bulge bending mechanism, which is more efficient than the additional form required for water expansion molding pumps.

[0103] This invention employs a multi-stage stepped annealing process to achieve a Rockwell hardness range of 60-70R15T for press-fit high-pressure-resistant copper pipe fittings. Hardness exceeding 70HR15T can cause burrs during press-fit installation. Furthermore, excessive hardness after press-fit assembly can lead to springback and leakage. Hardness below 60HR15T reduces the pipe fitting's pressure resistance, making it prone to rupture under sudden pressure increases. This invention significantly improves the pressure resistance of the pipe fittings while ensuring good extensibility during molding.

[0104] This invention employs a multi-stage cleaning process and corn cob cleaning and polishing to achieve a smooth product surface free from defects such as rough streaks and red spots.

[0105] The manufacturing method of this invention solves the problems of bulging and thinning of the socket wall caused by the water-expansion flaring process. After the pipe fitting of this invention is press-fitted to the pipeline, it will not detach until the strength test pressure reaches 8 MPa to 11 MPa, demonstrating good pressure resistance. In contrast, the water-expansion molding process causes it to detach when the strength test pressure reaches 5 MPa to 6 MPa, resulting in poor pressure resistance.

[0106] Compared with the following comparative examples 1 / 2 / 3, in the comparative examples, after straight pipes are processed into copper pipe fittings, the socket and bulge are enlarged due to the water expansion process, resulting in the thickness of the socket and the thickness of the bulge being less than the thickness of the main body. In contrast, in this invention, after straight pipes are processed into copper pipe fittings, they are processed by mechanical extrusion, resulting in the thickness of the socket and the thickness of the bulge being less than the thickness of the main body.

[0107] The components of the examples and comparative examples are shown in the table below. The examples were prepared using the preparation method described herein.

[0108] Example

[0109] Example Test Results

[0110] 12 HR15T60-70 0.6MPa 1.6MPa 8MPa-11MPa 15 HR15T60-70 0.6MPa 1.6MPa 8MPa-11MPa 18 HR15T60-70 0.6MPa 1.6MPa 8MPa-11MPa 22 HR15T60-70 0.6MPa 1.6MPa 8MPa-11MPa 28 HR15T60-70 0.6MPa 1.6MPa 8MPa-11MPa

[0111] Comparative Example 1 15-M

[0112] 1) Blanking: The raw material for blanking is straight pipe TP2 H80, and the blanking dimensions are: outer diameter D15mm × wall thickness H1.3mm × length L96mm;

[0113] 2) Bending: The bending machine is used to bend and form the shape;

[0114] 3) Water-expanded molding: Place the bent pipe fitting into the mold, insert the water-expanded mandrel, inject water into the water inlet hole in the center of the mandrel, pressurize the water pump for 25 seconds, and hold the pressure for 3 seconds. The semi-finished pipe fitting after water expansion molding includes the semi-finished body, the semi-finished socket and the semi-finished flared part. The wall thickness of the semi-finished socket is 1.2mm and the thickness of the semi-finished flared part is 1.18mm.

[0115] 4) Finishing: Use a finishing machine to finish the edges until the weight meets the requirements;

[0116] 5) End bulging: Place the flat-end pipe fitting into the end bulging mold, and simultaneously push in the edge rolling sleeve and the flaring mandrel to perform end bulging. The pipe fitting after end bulging includes the body, the socket and the bulge. The wall thickness of the body is 1.3mm, the wall thickness of the socket is 1.2mm, and the wall thickness of the bulge is 1.28mm.

[0117] 6) Inspection;

[0118] 7) Cleaning: Vibration, polishing, cleaning and drying;

[0119] 8) Inspect the packaging.

[0120] Comparative Example 2 22-M

[0121] 1) Blanking: The raw material for blanking is straight pipe TP2 H80, and the blanking dimensions are: outer diameter D22mm × wall thickness H1.3mm × length L115mm;

[0122] 2) Bending: The bending machine is used to bend and form the shape;

[0123] 3) Water-expanded molding: Place the bent and shaped pipe fitting into the mold, insert the water-expanded mandrel, inject water into the water inlet hole in the center of the mandrel, pressurize the water pump for 25 seconds, and hold the pressure for 3 seconds. The water-expanded pipe fitting semi-finished product includes the semi-finished product body, the semi-finished product socket and the semi-finished product flared part. The wall thickness of the semi-finished product socket is 1.2mm, and the wall thickness of the semi-finished product flared part is 1.18mm.

[0124] 4) Finishing: Use a finishing machine to finish the edges until the weight meets the requirements;

[0125] 5) End bulging: Place the flat-end pipe fitting into the end bulging mold, and simultaneously push in the edge rolling sleeve and the flaring mandrel to perform end bulging. The pipe fitting after end bulging includes the body, the socket and the bulge. The wall thickness of the body is 1.3mm, the wall thickness of the socket is 1.2mm, and the wall thickness of the bulge is 1.28mm.

[0126] 6) Inspection;

[0127] 7) Cleaning: Vibration, polishing, cleaning and drying;

[0128] 8) Inspect the packaging.

[0129] Comparative Example 3 28-M

[0130] 1) Blanking: The raw material for blanking is straight pipe TP2 H80, and the blanking dimensions are: outer diameter D28mm × wall thickness H1.38mm × length L125mm;

[0131] 2) Bending: The bending machine is used to bend and form the shape;

[0132] 3) Water-expanded molding: Place the bent pipe fitting into the mold, insert the water-expanded mandrel, inject water into the water inlet hole in the center of the mandrel, pressurize the water pump for 25 seconds, and hold the pressure for 3 seconds. The semi-finished pipe fitting after water expansion molding includes the semi-finished body, the semi-finished socket and the semi-finished flared part. The wall thickness of the semi-finished socket is 1.28mm and the wall thickness of the semi-finished flared part is 1.25mm.

[0133] 4) Finishing: Use a finishing machine to finish the edges until the weight meets the requirements;

[0134] 5) End bulging: Place the flat-end pipe fitting into the end bulging mold, and simultaneously push in the edge rolling sleeve and the flaring mandrel to perform end bulging. The pipe fitting after end bulging includes the body, the socket and the bulge. The wall thickness of the body is 1.38mm, the wall thickness of the socket is 1.28mm and the wall thickness of the bulge is 1.35mm.

[0135] 6) Inspection;

[0136] 7) Cleaning: Vibration, polishing, cleaning and drying;

[0137] 8) Inspect the packaging.

[0138] Comparative test results

[0139] 15-M HR15T35-45 0.6MPa 1.6MPa 6MPa~7MPa 22-M HR15T35-45 0.6MPa 1.6MPa 6MPa~7MPa 28-M HR15T35-45 0.6MPa 1.6MPa 5MPa~6MPa

[0140] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a high-pressure-resistant socket brass pipe fitting by a press-in method, characterized by, Used for the production of press-fit high-pressure-resistant copper pipe fittings with sockets; The press-fit high-pressure resistant copper pipe fitting includes: a main body, sockets respectively located at both ends of the main body, and two bulges respectively located at the outer ends of the two sockets. The main body is bent, and the wall thickness H1 of the bulges is greater than the wall thickness H of the main body, and the wall thickness H2 of the sockets is greater than the wall thickness H of the main body. Each of the bulges includes a first inclined section and a curved section connected to each other, the first inclined section being connected to the socket, the first inclined section being inclined outward of the socket, and the curved section being curved inward of the socket. The preparation method uses a tapered flaring mechanism and a bulging bending mechanism; The tapered flaring mechanism includes: a tapered flaring mold and two tapered mandrels, wherein the tapered flaring mold has a tapered forming cavity; The bulge bending mechanism includes: a bulge bending mold and two bulge forming groups, wherein the bulge bending mold has a bulge bending cavity; The preparation method includes: Step S1: Use a bending machine to bend the straight pipe into a bent pipe; Step S2: Place the bent tube into the tapered forming cavity, the tapered forming cavity positions the middle part of the bent tube, and the two tapered mandrels respectively press the two ends of the bent tube so that both ends of the bent tube form a tapered forming part and a flared part, and the bent tube forms a tapered bent tube; Step S3: Place the tapered bend into the bulge bending cavity. The bulge bending cavity positions the middle part of the tapered bend. The middle part of the tapered bend forms the main body. The two bulge forming groups respectively squeeze the two ends of the tapered bend. The tapered forming part forms the socket, and the flared part forms the bulge, thus realizing the finished product processing. The tapered forming cavity includes: a first positioning part, tapered forming parts located at both ends of the first positioning part, and tapered flared parts located at both ends of the two tapered forming parts. In step S2, the first positioning part positions the middle part of the bent tube, and the tapered mandrel presses the end of the bent tube so that the outer wall of the end of the bent tube abuts against the inner wall of the tapered forming part and the inner wall of the tapered flaring part, and the end of the bent tube forms the tapered forming part and the flaring part. The bulge bending cavity includes: a second positioning part, a socket shaping part located at both ends of the second positioning part, and a bulge part located at both ends of the two socket shaping parts. In step S3, the second positioning part positions the middle part of the tapered bend, and the middle part of the tapered bend forms the main body. The bulge forming group extrudes the tapered forming part and the flared part. The outer wall of the tapered forming part abuts against the inner wall of the socket shaping part to form the socket. The outer wall of the flared part abuts against the inner wall of the bulge part to form the bulge. The flared section includes a second inclined section and a straight section that are connected to each other; In step S3, the tapered bend is placed in the bulging bending cavity, the second positioning part positions the middle part of the tapered bend, the middle part of the tapered bend forms the main body, the bulging forming group extrudes the tapered forming part and the flared part, the tapered forming part forms the socket, the second inclined section forms the first inclined section, and the straight section forms the bending section, thus realizing the finished product processing; The bulge forming assembly includes: a rolled edge sleeve and a bulge core rod. The rolled edge sleeve is a hollow structure with open ends. One end of the rolled edge sleeve has an arc-shaped forming groove that communicates with its hollow portion. The bulge core rod penetrates through the hollow portion of the rolled edge sleeve. In step S3, the tapered bend is placed in the bulging bending cavity, the second positioning part positions the middle part of the tapered bend, the middle part of the tapered bend forms the main body, the bulging core extrudes the tapered forming part, the rolled edge sleeve extrudes the straight section, the tapered forming part forms the socket, the second inclined section forms the first inclined section, the straight section extends into the arc-shaped forming groove, bends and abuts against the bulging core to form the bent section, thus realizing the finished product processing.

2. The method of claim 1, wherein the method further comprises the steps of: providing a copper pipe; and providing a high pressure resistant socket; and coupling the copper pipe to the high pressure resistant socket. The tapered mandrel includes a tapered portion and a first mandrel body that are connected to each other; In step S2, the tapered mandrel presses the end of the bent tube so that the portion of the tapered part pressing the bent tube forms the tapered forming part, and the portion of the first mandrel body pressing the bent tube forms the flared part; The bulging core rod includes a cylindrical part and a second core rod body that are connected to each other; In step S3, the rolled edge sleeve and the bulging mandrel squeeze the end of the tapered bend so that the cylindrical part squeezes the tapered forming part to form the socket. The rolled edge sleeve squeezes the straight cylindrical section in the flared part. The straight cylindrical section extends into the arc-shaped forming groove, bends, and abuts against the outer wall of the second mandrel body to form the curved section.

3. The method for preparing the press-fit high-pressure-resistant copper pipe fitting according to claim 2, characterized in that, Before step S1, the straight tube is subjected to semi-finished annealing treatment. When the wall thickness H of the straight tube is in the range of 1 to 1.4 mm, the annealing temperature is 480-510℃ and the annealing time is 30 to 40 min. When the wall thickness H of the straight tube is ≥1.5 mm, the annealing temperature is 480-510℃ and the annealing time is 40 to 55 min. After step S3, the finished product undergoes a finished product annealing process, using a progressive processing method; The progressive processing method includes: Step A1: Annealing temperature of the inner liner of the heating furnace is 380~400℃, and the outer liner of the heating furnace is set at 430~450℃ for 15~20 min. Step A2: Annealing temperature of the inner liner of the heating furnace is 380~400℃, and the outer liner of the heating furnace is set at 450~470℃ for 25~35 minutes. Step A3: Annealing temperature of the inner liner of the heating furnace is 380~400℃, and the outer liner of the heating furnace is set at 480~510℃ for 85~100 min.

4. The method for preparing the press-fit high-pressure-resistant copper pipe fitting according to claim 3, characterized in that, Before the semi-finished product annealing process, the straight tube is cleaned for the first time by vibrating, polishing, cleaning to remove copper shavings and oil stains, and then drying. The tapered bend that has been processed and formed is then cleaned a second time. The tapered bend is vibrated, polished, and cleaned to remove copper shavings and oil stains, and then dried. The finished product is then subjected to a third cleaning process, including vibration, polishing, cleaning, and drying. The second cleaning process involves washing with dried corncob fragments.

5. The method for preparing the press-fit high-pressure-resistant copper pipe fitting according to claim 4, characterized in that, The tapered bend is finished by a flat-end machine after the second cleaning. After the finished product undergoes the finished product annealing treatment, a sealing ring is inserted into the bulge, and the finished product is inspected and packaged.

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