CN111889983A - Manufacturing method of clamping and pressing type steel pipe fitting with threads - Google Patents
Manufacturing method of clamping and pressing type steel pipe fitting with threads Download PDFInfo
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- CN111889983A CN111889983A CN202010779308.6A CN202010779308A CN111889983A CN 111889983 A CN111889983 A CN 111889983A CN 202010779308 A CN202010779308 A CN 202010779308A CN 111889983 A CN111889983 A CN 111889983A
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- forging
- pipe fitting
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- steel pipe
- clamping
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
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Abstract
The invention discloses the field of machining and forming, in particular to a method for manufacturing a clamping and pressing type steel pipe fitting with threads, which comprises the following steps: preparing a high-pressure forging blank of the clamping and pressing type pipe fitting with the threads at the metal recrystallization temperature; then, forming a middle hole of the clamping and pressing type steel pipe fitting; and finally, performing post-forging treatment. The invention replaces the current situation of year-round import, reduces the production cost, greatly saves the labor and time, and reduces the processing period; the defect of loose material of the solid inner layer of the large steel billet is overcome by adopting high-pressure forging, in addition, the forging process is to forge at the metal recrystallization temperature, the size error caused by expansion with heat and contraction with cold is avoided, the shape and size of a finish-forged workpiece are easy to control, meanwhile, the surface of a forged piece is not oxidized, burnt and the like, and the surface quality is high.
Description
Technical Field
The invention relates to the field of metal processing, in particular to a manufacturing method of a clamping and pressing type steel pipe fitting with threads.
Background
The existing steel clamping-pressing type threaded pipe fittings adopt argon arc welding process for more than 95 percent and friction welding process for about 10 percent of high-end field (patent number: ZL200610096951.9)
The process for argon arc welding of the clamping and pressing type steel pipe fitting with the threads comprises the following steps (see the attached figures 1-2 of the specification): 1, threaded end: steel precision casting, thread turning and welding port turning; 2, clamping a female end: pipe-cutting-flattening-end forming-smooth-plane-cleaning. 1 and 2, aligning the welding port parts, and adopting argon arc welding without adding wires for welding. The basic process is that the mouth parts of two parts to be welded are aligned, and two points are spot-welded in the 180-degree circumferential direction at the joint of the outer diameter, so that the two parts are combined together. Then clamping the outlet part to make the outlet part rotate at a constant speed of 360 degrees, ensuring that the rotation axis is overlapped with the axis of the circumferential surface of the welding opening, and simultaneously fixing the welding gun to ensure that the distance from the gun tip to the welding seam is constant, and the distance is generally 2-4 mm. The circumferential corner formed from the arc starting point to the arc extinguishing point of the welding is generally larger than 360 degrees so as to ensure the welding of the starting point and the tail point of the welding line to be complete. The argon flow is to ensure that the welding line is silvery white, and the welding line is to be rapidly cooled, the shorter the time of the welding line at the temperature of 450-850 ℃, the better, so as to avoid intergranular corrosion.
The steel clamping and pressing type pipe fitting product with the threads is also connected with the threads 1 and the thin-wall pipe forming parts 2 which are precisely cast by argon arc welding. During argon arc welding, the welding time is long, the high-temperature retention time of a welding line and a near seam area is long, and the cooling speed is slow. The weld region has microscopic chemical composition segregation. Under the action of welding heat circulation, the heat affected zone at the peak temperature of 600-1000 ℃ belongs to the sensitized zone of the welding joint, and carbide Cr is formed along the grain boundary23C6The precipitates of (2) are liable to cause intergranular corrosion in the sensitized area under the action of a corrosive medium, and therefore, cannot be used in severe environments or in situations where corrosive liquids are transported. The quality of the argon arc welding head is easily affected by conditions such as welding process, welding equipment, gas protection, the technical level of welding workers and the like, and the unstable factors of the product quality are high.
The friction welding process of clamping and pressing steel pipe with thread includes the following steps: 1, steel precision casting; 2, thick-wall steel pipe making, material breaking and pipe end forming; and connecting the two parts 1 and 2 by friction welding, and finally, machining threads and a female end by numerical control lathing.
In the friction welding process, the thread part is clamped at the rotating end of the welding machine to rotate at a high speed, the female end is fixed in the rotating axis direction of the thread part and approaches to the rotating thread end, workpieces on two sides are contacted and pressed, bonding and shearing are carried out on a friction interface, friction heat is generated, the temperature at the friction interface is increased, and the friction interface is gradually covered by a layer of high-temperature viscoplastic metal. Under the activation of heat and deformation, the layer of the viscoplastic metal is dynamically recrystallized. Along with the conduction of friction heat to workpieces on two sides, the temperature on two sides of a welding surface is gradually increased, and under the action of axial pressure, metal in a welding area generates radial plastic flow, so that flash is formed, and the axial shortening is gradually increased. When the temperature distribution and deformation of the friction welding zone reach a certain degree, the braking is started and the axial force is rapidly increased to the set upsetting pressure. In the upsetting process and the pressure maintaining process after upsetting, metals at the welding area are firmly welded together through mutual diffusion and recrystallization, so that the whole welding process is completed.
Compared with argon arc welding technology, the metal in the friction welding area is a forging structure, and the welding defects and welding embrittlement phenomena related to melting and solidification metallurgy, such as thick columnar crystals, segregation, inclusions, cracks, air holes and the like, are not generated; secondly, the axial pressure and the torque jointly act on the friction welding surface and the near area thereof, and some mechanical metallurgical effects such as grain refinement, compact structure, impurity dispersion distribution and the like are generated.
The thread part of the friction welding is processed by a casting, is a high-energy consumption and high-pollution process, has the defects of shrinkage porosity, inclusion and the like, causes the thread part or the welding port part to be influenced by environmental factors such as vibration, expansion with heat and contraction with cold in the use process of the pipeline, and causes the shrinkage or inclusion part of the casting to be leaked and failed; secondly, paraffin mineral lubricating oil is used for forming the thick-wall seamless pipe, so that the thick-wall seamless pipe is difficult to clean, more waste oil and cleaning wastewater are generated, and the environment is polluted; in addition, because the friction stop time and the upsetting force are not easy to control in the friction welding, the false welding and the cold welding can occur, the pipe is suddenly disconnected in the application process, and the application process of the friction welding is very dangerous in the high-temperature or high-pressure pipeline.
Disclosure of Invention
The invention aims to provide a method for manufacturing a clamping and pressing type steel pipe fitting with threads.
A manufacturing method of a clamping and pressing type steel pipe fitting with threads is characterized in that: and (3) carrying out high-pressure forging molding on the steel raw material below the recrystallization temperature to form a blank of the thread clamping and pressing pipe fitting, and finally carrying out finish machining and molding.
The method is realized by the following technical scheme:
a manufacturing method of a clamping and pressing type steel pipe fitting with threads comprises the following steps:
(1) preparing a blank: and cutting off the head and the tail of a qualified steel ingot, forging the steel ingot into a forging blank meeting the requirements, and determining the central point of the punching middle hole according to the actual shape and size of the required clamping and pressing type steel pipe fitting.
(2) Forming a middle hole of the clamping and pressing type steel pipe fitting: and (2) performing high-pressure forging, reaming and die positioning at the punching central point of the middle hole of the blank at the metal recrystallization temperature, wherein during the high-pressure forging, firstly, the forging and punching are performed along the central line of the middle hole in one direction, and then, the forging and punching are performed symmetrically along the central line of the middle hole in the opposite direction.
The holes punched by forging along the center line of the middle hole in one direction can be blind holes, and then the punched holes are punched by forging in the opposite direction.
When the punching holes are forged and punched, the central line position of the middle hole 3 is basically coincided with the central line position of the forged blank so as to ensure that the requirements of drawings are met.
(3) The post-forging treatment comprises the following steps:
A. heat treatment after forging: annealing heat treatment is carried out on the forge piece by using a trolley type resistance furnace with the rated power of 420KW, and due to the characteristics of material characteristics and large forge piece, the forge piece needs to be subjected to hot charging and annealing after the forging is finished, so that the annealing heat preservation time is ensured, the internal stress of a forging blank is eliminated, and otherwise the forge piece is very easy to crack;
B. ultrasonic flaw detection: firstly, roughly processing six surfaces of a forged blank to be white (improving the precision of flaw detection), and carrying out ultrasonic primary flaw detection on six surfaces of the forged blank according to the standard; after the initial detection is qualified, roughly processing the forging stock to the size before heat treatment, polishing edges and corners of an inner hole and an outer surface to form round corners, and performing ultrasonic secondary flaw detection on the forging piece according to the JB4730 standard;
C. and (3) heat treatment: normalizing and tempering the forged piece by using a trolley type resistance furnace with the rated power of 420 KW;
D. finish machining: finish machining the clamping and pressing type steel pipe fitting according to the requirement of a finish machining drawing, and finish machining of threads, the hexagonal thread part, the middle hole and the clamping and pressing female end 2 by using a vertical lathe and a boring lathe respectively;
in the embodiment, each procedure from the initial material selection to the finish machining is quite important, and comprises the preparation of a forging blank and the forming treatment of the middle hole 3 realized by forging and punching, wherein the position of the middle hole is constantly penetrated axially and is symmetrical to the central line during the forging and punching, and in order to avoid the rejection of the punched hole, the center of the middle hole 3 is gradually made to accord with the qualified position by means of a female die in the process of shifting and reaming. The unidirectional punching blind hole positioned on the surface of the middle hole enhances the density of the materials around the middle hole 3. And (4) performing post-forging treatment, wherein the post-forging treatment comprises reprocessing of the middle hole and machining of the middle hole.
The invention has the advantages that the current situation of year-round import is replaced, the production cost is reduced, the manpower and the time are greatly saved, and the processing period is reduced; the method adopts high-pressure forging, eliminates the defect of loose material of the solid inner layer of the large steel billet, and in addition, the forging process is to forge at the metal recrystallization temperature, so that the size error caused by expansion with heat and contraction with cold is avoided, the shape and size of a finish-forged workpiece are easy to control, meanwhile, the surface of a forged piece is not oxidized, burnt loss and the like, and the surface quality is higher, so the forging precision of hot finish forging and warm finish forging is lower than that of cold finish forging. In addition, the work hardening effect by the finish forging can significantly improve the strength of the cold forged part. However, in the cold forging process, the deformation resistance is large, the plasticity of the workpiece is poor, the filling effect is poor, and the requirements on equipment and a die are high, so that the forming of parts with complex shapes is difficult.
Has the advantages that:
the clamping and pressing type pipe fitting with the threads is subjected to high-pressure forging at the metal recrystallization temperature, and the thread part and the socket part are integrated, so that the defects and risks of welding seams in other machining processes of the clamping and pressing type pipe fitting with the threads are eliminated. High-pressure forging at the recrystallization temperature has a work hardening effect, can improve the material properties, has excellent strength properties, consumes little material, basically has no waste, and does not pollute the environment due to energy consumption and thermal state generated by heating. In addition, the manufacturing method has extremely high workpiece precision and can well control the machining allowance; the processing efficiency is extremely high, can reach 60-100 pieces/minute, and is 10-20 times of argon arc welding and friction welding processes.
Drawings
FIG. 1 is a schematic diagram of argon arc welding principle in the prior art;
FIG. 2 is a schematic diagram of a friction welding principle in the prior art;
FIG. 3 is a schematic cross-sectional view of a press-fit steel pipe fitting according to the present invention.
In the figure: a threaded end 1, a card press-fit end 2 and a middle hole 3.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Referring to the attached fig. 1-3 of the specification, the method of the embodiment comprises the following steps:
(1) preparing a blank: and cutting off the head and the tail of a qualified steel ingot, forging the steel ingot into a forging blank meeting the requirements, and determining the central point of the punching middle hole according to the actual shape and size of the required clamping and pressing type steel pipe fitting.
(2) Forming a middle hole of the clamping and pressing type steel pipe fitting: and (2) performing high-pressure forging, reaming and die positioning at the punching central point of the middle hole of the blank at the metal recrystallization temperature, wherein during the high-pressure forging, firstly, the forging and punching are performed along the central line of the middle hole in one direction, and then, the forging and punching are performed symmetrically along the central line of the middle hole in the opposite direction.
The holes punched by forging along the center line of the middle hole in one direction can be blind holes, and then the punched holes are punched by forging in the opposite direction.
When the punching holes are forged and punched, the central line position of the middle hole 3 is basically coincided with the central line position of the forged blank so as to ensure that the requirements of drawings are met.
(3) The post-forging treatment comprises the following steps:
A. heat treatment after forging: annealing heat treatment is carried out on the forge piece by using a trolley type resistance furnace with the rated power of 420KW, and due to the characteristics of material characteristics and large forge piece, the forge piece needs to be subjected to hot charging and annealing after the forging is finished, so that the annealing heat preservation time is ensured, the internal stress of a forging blank is eliminated, and otherwise the forge piece is very easy to crack;
B. primary flaw detection: carrying out ultrasonic primary flaw detection on six surfaces of a forged blank according to the standard when the six surfaces of the forged blank are subjected to rough machining and are white (the flaw detection accuracy is improved);
C. secondary flaw detection: after the initial detection is qualified, roughly processing the forging stock (including boring the middle hole 3) to the size before heat treatment, polishing edges and corners of an inner hole and an outer surface to form round corners, and performing ultrasonic secondary flaw detection on the forging piece according to the JB4730 standard;
D.N + T Heat treatment: normalizing and tempering the forged piece by using a trolley type resistance furnace with the rated power of 420 KW;
E. and (3) carrying out tertiary flaw detection: the shape of the forging and the middle hole 3 are processed to rough machining size for final ultrasonic flaw detection;
F. finish machining: finish machining the clamping and pressing type steel pipe fitting according to the requirement of a finish machining drawing, and finish machining of threads, the hexagonal thread part, the middle hole and the clamping and pressing female end 2 by using a vertical lathe and a boring lathe respectively;
in the embodiment, each procedure from the initial material selection to the finish machining is quite important, and comprises the preparation of a forging blank and the forming treatment of the middle hole 3 realized by forging and punching, wherein the position of the middle hole is constantly penetrated axially and is symmetrical to the central line during the forging and punching, and in order to avoid the rejection of the punched hole, the center of the middle hole 3 is gradually made to accord with the qualified position by means of a female die in the process of shifting and reaming. The unidirectional punching blind hole positioned on the surface of the middle hole enhances the density of the materials around the middle hole 3. And (4) performing post-forging treatment, wherein the post-forging treatment comprises reprocessing of the middle hole and machining of the middle hole.
While there have been shown and described the fundamental principles and essential features of the invention and advantages thereof, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof; the present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein, and any reference signs in the claims are not intended to be construed as limiting the claim concerned.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. A manufacturing method of a clamping and pressing type steel pipe fitting with threads is characterized by comprising the following steps: (1) preparing a high-pressure forging blank of the clamping and pressing type pipe fitting with the threads at the metal recrystallization temperature; (2) performing forming treatment on a middle hole of the clamping and pressing type steel pipe fitting, wherein the forming treatment is realized by forging, punching and reaming, and when the forging, punching is performed, the central line position of the forged middle hole is ensured to be basically coincident with the central line position of a forging blank; (3) post-forging processing, including reprocessing of the intermediate holes.
2. The method for manufacturing a press-fit steel pipe fitting with a thread according to claim 1, wherein: in the step (2), during the intermediate hole forming treatment, firstly, forging and punching are carried out along the central line of the intermediate hole in one direction, then, forging and punching are carried out along the central line of the intermediate hole in the opposite direction, and then, hole expansion is carried out.
3. The method for manufacturing a press-fit steel pipe fitting with a screw according to claim 2, wherein: in the step (2), firstly, the hole punched by forging along the central line of the middle hole in one direction is a blind hole, and then, the hole is punched by forging in the opposite direction to be communicated.
4. The method for manufacturing a press-fit steel pipe fitting with a screw according to claim 2, wherein: in the step (2), the hole expansion is realized by using a female die, the hole expansion enables central lines punched in two directions to be uniform, and meanwhile, the central line of the middle hole is accurately superposed to a specified position.
5. The method for manufacturing a press-fit steel pipe fitting with a screw according to claim 2, wherein: in the step (2), the forming treatment of the middle hole adopts unidirectional forging and punching of a blind hole.
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| CN202010779308.6A CN111889983B (en) | 2020-08-05 | 2020-08-05 | Manufacturing method of clamping and pressing type steel pipe fitting with threads |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0694170A (en) * | 1992-09-14 | 1994-04-05 | Kawatetsu Chiyuubitsuku Kk | Manufacture of pipe joint for oil well |
| JP2000102836A (en) * | 1998-09-29 | 2000-04-11 | Musashi Seimitsu Ind Co Ltd | Method of forming hollow ball stud |
| CN101462225A (en) * | 2009-01-14 | 2009-06-24 | 宝鸡市永盛泰钛业有限公司 | Technique for processing honing tube |
| CN101774107A (en) * | 2009-12-31 | 2010-07-14 | 上海新闵重型锻造有限公司 | Method for forging Venturi tubes |
| CN102275066A (en) * | 2011-07-11 | 2011-12-14 | 山推工程机械股份有限公司 | Method for manufacturing pin bush of bulldozer track |
| CN104476120A (en) * | 2014-11-06 | 2015-04-01 | 柳州欧维姆机械股份有限公司 | Forming technical method of square through plate with wedge-shaped through hole |
| CN105328095A (en) * | 2015-07-29 | 2016-02-17 | 江阴南工锻造有限公司 | Low-carbon high-alloy steel forging technology |
-
2020
- 2020-08-05 CN CN202010779308.6A patent/CN111889983B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0694170A (en) * | 1992-09-14 | 1994-04-05 | Kawatetsu Chiyuubitsuku Kk | Manufacture of pipe joint for oil well |
| JP2000102836A (en) * | 1998-09-29 | 2000-04-11 | Musashi Seimitsu Ind Co Ltd | Method of forming hollow ball stud |
| CN101462225A (en) * | 2009-01-14 | 2009-06-24 | 宝鸡市永盛泰钛业有限公司 | Technique for processing honing tube |
| CN101774107A (en) * | 2009-12-31 | 2010-07-14 | 上海新闵重型锻造有限公司 | Method for forging Venturi tubes |
| CN102275066A (en) * | 2011-07-11 | 2011-12-14 | 山推工程机械股份有限公司 | Method for manufacturing pin bush of bulldozer track |
| CN104476120A (en) * | 2014-11-06 | 2015-04-01 | 柳州欧维姆机械股份有限公司 | Forming technical method of square through plate with wedge-shaped through hole |
| CN105328095A (en) * | 2015-07-29 | 2016-02-17 | 江阴南工锻造有限公司 | Low-carbon high-alloy steel forging technology |
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