CN112775631B - Pressure pipe tee extrusion forming method - Google Patents
Pressure pipe tee extrusion forming method Download PDFInfo
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- CN112775631B CN112775631B CN202110106906.1A CN202110106906A CN112775631B CN 112775631 B CN112775631 B CN 112775631B CN 202110106906 A CN202110106906 A CN 202110106906A CN 112775631 B CN112775631 B CN 112775631B
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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
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C23/00—Extruding metal; Impact extrusion
- B21C23/02—Making uncoated products
- B21C23/03—Making uncoated products by both direct and backward extrusion
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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Abstract
The invention provides a pressure pipe tee extrusion forming method, which comprises the following steps: using a continuous casting billet as a raw material, and preparing an extrusion blank by adopting a construction forming method; placing the extrusion blank in a combined three-way die, and sequentially extruding the three-way branch pipe and the three-way main pipe by adopting an integrated extrusion forming process to prepare a three-way blank; and demolding the tee-joint-shaped blank by adopting the combined tee-joint mold, and machining to obtain the finished product of the pressure pipe tee joint. The invention provides an extrusion forming method of a pressure pipe tee joint, which reduces welding seams of the pressure pipe tee joint, improves the tensile property of materials and the uniformity of impact energy, improves the safety under the condition of complex working condition loads and shortens the manufacturing period.
Description
Technical Field
The invention relates to the field of nuclear power main pipeline manufacturing, in particular to a pressure pipe tee extrusion forming method.
Background
In the atomic energy fast reactor project, the pressure pipe is used for connecting a primary loop sodium pump supporting outlet and a large grid plate header, provides a flow channel for cooling sodium liquid, and is a part of a primary loop main cooling system flow channel.
Once installed, pressure pipes are not accessible for in-service inspection and are non-replaceable components. The fast reactor pressure pipe has complex working conditions, including pre-service pressure test, installation, sodium filling, reactor starting, material changing, full power, predicted operation events, rare accidents and limit accidents, and bearing loads including pressure, temperature, fluid flow-induced vibration and main pump rotation load, so that failure modes of the fast reactor pressure pipe include strength, low cycle fatigue and high cycle fatigue.
The tee joint is used as an important part of the pressure pipe, is similar to a pant shape, is large in size and complex in shape, and needs to break through the traditional blank forming technology to change rough forming into high-quality and high-precision forming technology in order to reduce machining amount, reduce machining difficulty and keep the integrity of a metal streamline.
At present, in the field of manufacturing of nuclear power main pipelines, a scientific and reasonable pressure pipe tee extrusion forming method does not exist.
Disclosure of Invention
Technical problem to be solved
In view of the above, the invention provides a pressure pipe tee extrusion forming method, aiming at the technical problem that the existing tee manufacturing process of a nuclear power fast reactor pressure pipe is lacked, which can reduce the welding seams of the pressure pipe tee, improve the tensile property of materials and the uniformity of impact energy, improve the safety and shorten the manufacturing period under the condition of complex working condition loads.
(II) technical scheme
The invention provides a pressure pipe tee extrusion forming method, which comprises the following steps: using a continuous casting billet as a raw material, and preparing an extrusion blank by adopting a construction forming method; placing the extruded blank in a combined three-way die, and sequentially extruding the three-way branch pipe and the three-way main pipe by adopting an integrated extrusion forming process to manufacture a three-way-shaped blank; and demolding the tee-joint-shaped blank by adopting the combined tee-joint mold, and machining to obtain the finished product of the pressure pipe tee joint.
According to an embodiment of the present invention, before the step of forming the extruded blank by using the continuous casting slab as a raw material and using the construction forming method, the method further comprises: and sequentially carrying out electric melting rough smelting, external refining and continuous casting forming processes on the scrap steel to obtain the continuous casting billet.
According to the embodiment of the invention, the continuous casting billet is made of 316H material.
According to an embodiment of the present invention, in the step of sequentially subjecting the scrap steel to electric smelting and primary smelting, external refining and continuous casting forming processes to obtain the continuous casting billet, the external refining includes: and refining the raw materials subjected to electric smelting and rough smelting by sequentially adopting a vacuum oxygen blowing decarburization method, ladle refining and a vacuum degassing method.
According to an embodiment of the present invention, in the step of sequentially subjecting the scrap steel to electric smelting and primary smelting, external refining and continuous casting forming processes to obtain the continuous casting billet, the continuous casting forming process includes: and (3) adopting a vertical bending type continuous casting machine and combining an electromagnetic stirring complete device to carry out continuous casting forming.
According to an embodiment of the present invention, in the step of forming the extrusion billet by using the continuous casting billet as a raw material and using a construction forming method, the construction forming method sequentially comprises: the method comprises the following steps of continuous casting billet sawing, surface milling and grinding, surface cleaning treatment, stacking, vacuum sealing and welding, weld joint grinding and heating before forging, high-temperature high-pressure large-deformation forging and pressing, high-temperature diffusion, multidirectional forging, chamfering, rounding, upsetting, punching and strut reaming.
According to the embodiment of the invention, the high-temperature high-pressure large-deformation forging and the multidirectional forging are carried out by adopting a press machine.
According to an embodiment of the present invention, before the placing the extrusion billet in the three-way combined die, further comprises: heating the extrusion billet to 1100-1200 ℃.
According to an embodiment of the present invention, before the placing the extrusion billet in the three-way combined die, further comprises: and uniformly smearing a lubricant on the inner wall of the cavity of the combined three-way die.
According to the embodiment of the invention, the step of sequentially extruding the three-way branch pipe and the three-way main pipe by adopting an integrated extrusion forming process to manufacture the three-way blank comprises the following steps: the extrusion blank is a forged round blank, and the extrusion blank is made into a tee-shaped blank by driving an extrusion punch through an extruder and sequentially carrying out a forward extrusion process and a backward extrusion process.
According to the embodiment of the invention, the extrusion punch head is composed of a solid cylindrical shaft and a cylindrical boss which is positioned at one end of the cylindrical shaft and has a diameter larger than that of the cylindrical shaft, wherein the cylindrical boss is used as a forward extrusion punch head, the cylindrical shaft is used as a backward extrusion punch head, and the diameter of the cylindrical boss is the same as that of the inner wall of the cavity main pipe of the combined three-way die.
According to an embodiment of the invention, wherein the forward extrusion process comprises: and extruding and upsetting the extruded blank by using the forward extrusion punch to enable the extruded blank to fill a branch pipe cavity of the combined three-way die.
According to an embodiment of the invention, wherein the back extrusion process comprises: and reversely extruding the extrusion blank into the combined three-way die by using the reverse extrusion punch until the extrusion blank is full of the main pipe cavity of the combined three-way die.
According to an embodiment of the present invention, wherein the forward extrusion process and the backward extrusion process further comprise: the extrusion speed is controlled to be 0.5-2mm/s.
According to an embodiment of the present invention, wherein the forward extrusion process and the backward extrusion process further comprise: and controlling the machining allowance of the extruded blank single-side machine to be 10-20mm.
According to an embodiment of the present invention, the demolding the three-way-shaped blank by using the combined three-way mold includes: the combined three-way die is a combined die with a split middle part, after extrusion is finished, a sheath used for fixing the combined three-way die is removed, and then the combined three-way die is disassembled, so that demoulding of the three-way-shaped blank is finished.
According to the embodiment of the invention, in the step of manufacturing the finished pressure pipe tee by machining, the machining comprises rough machining, solution treatment and finish machining in sequence.
According to an embodiment of the present invention, wherein the rough machining further comprises: and fixing the tee-joint-shaped blank on a workbench of a numerical control boring machine by using a positioning tool clamp, and correcting a positioning reference.
According to an embodiment of the invention, wherein the roughing comprises: and sequentially machining the inner hole of the main tee pipe, the inner hole of the branch tee pipe and the residual tee area by adopting a numerical control lathe arranged on the workbench of the numerical control boring machine, wherein the single-side finish machining allowance for keeping the wall thicknesses of the inner hole of the main tee pipe, the inner hole of the branch tee pipe and the residual tee area is not less than 15mm.
According to the embodiment of the invention, the machining of the tee joint residual area by using the numerical control lathe comprises the following steps: firstly, aligning and positioning the direction by using the positioning tool clamp, and then feeding to machine a left branch pipe of the tee joint; after the three-way left branch pipe is machined, the three-way pipe is turned over by 180 degrees, the positioning tool fixture is used again for aligning and positioning, and then the three-way right branch pipe is machined by feeding.
According to an embodiment of the invention, wherein the solution treatment comprises: and fully carrying out solid solution heating on carbides in the roughly processed extruded blank to an austenitic stainless steel matrix, and then carrying out annealing treatment.
According to an embodiment of the invention, wherein the solution heating further comprises: controlling the temperature rise rate to be not more than 150 ℃/h, heating the roughly processed extruded shape blank to the temperature range of 1060 ℃ +/-10 ℃, and preserving the temperature in the temperature range for at least 2 hours.
According to an embodiment of the present invention, after the finishing, further comprising: and polishing the parts which cannot be machined and the parts which do not meet the requirement of surface finish in the tee-joint-shaped blank, and forming the finished product of the pressure pipe tee after the finished product is detected to be qualified.
(III) advantageous effects
Compared with the prior art, the extrusion forming method for the pressure pipe tee joint provided by the invention at least has the following beneficial effects:
(1) The content of hydrogen in the raw materials can be effectively controlled by a high-purity stainless steel continuous casting process;
(2) The mechanical property uniformity of the pressure pipe is improved by the extrusion and machining forming processes of the tee joint. According to the pressure pipe tee extrusion forming method provided by the invention, the grain size of the formed tee is 2-3 grades through microscopic structure testing. After mechanical property test and sampling at any position of a test piece, the yield strength sigma of the material is measured 0.2 The fluctuation range of (A) is not more than 30MPa, and the fluctuation range of the impact absorption power is not more than 50J.
(3) Through tee bend integration extrusion forming process, adopt the form of not having the welding seam, under the complicated condition of pressure pipe operating mode load, improved inherent security, shortened equipment, welding manufacturing cycle.
Drawings
Fig. 1 schematically shows a structural view of a pressure pipe tee of an embodiment of the present invention.
Fig. 2 schematically shows a flow chart of a pressure pipe tee extrusion method according to an embodiment of the present invention.
FIG. 3 is a flow chart schematically illustrating the operation of the method for three-way extrusion forming of pressure tubes in accordance with an embodiment of the present invention.
Fig. 4 is a flow chart schematically illustrating the construction forming operation in the method for three-way extrusion forming of pressure pipes according to the embodiment of the present invention.
Figure 5 is a schematic diagram showing an extrusion process in a pressure pipe tee extrusion method according to an embodiment of the present invention.
Fig. 6 is a view schematically showing a structure of a three-way die for pressure pipes according to an embodiment of the present invention.
[ description of reference ]
1-a pressure pipe tee; 2-a combined three-way mold; 3-extruding the blank; 41-positive extrusion punch; 42-a reverse extrusion punch; 410-a detachable forward extrusion punch; 420-Detachable reverse extrusion punch.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all 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.
At present, in a nuclear power main pipeline, a pressure pipe part mainly comprises a tee joint, a bent pipe, a transition section, a sealing ring, a sealing assembly, a corrugated pipe assembly and the like, wherein the tee joint is positioned in an inlet cavity of a sodium pump and is welded with a pump joint sleeve.
FIG. 1 schematically illustrates a structural diagram of a pressure tube tee in accordance with an embodiment of the present invention.
As shown in fig. 1, the pressure pipe tee 1 is a large-caliber thin-walled pipeline, and includes a main pipe and two branch pipes, wherein the main pipe and the branch pipes are respectively located at two ends of the pressure pipe tee 1. In the embodiment of the invention, the pressure pipe tee 1 is similar to a pant shape, is constructed by curved surfaces and has a complex shape.
The tee joint is used as an important part of the pressure pipe, is large in size and complex in shape, needs to obtain a high-performance forging piece in order to reduce machining amount, reduce machining difficulty and keep the integrity of a metal streamline, and breaks through the traditional blank forming technology through a near-net forging forming technology to change rough forming into a high-quality and high-precision forming technology.
The invention provides an extrusion forming method of a pressure pipe tee joint, which comprises the steps of firstly extruding and integrally forming, and then machining.
Fig. 2 schematically shows a flow chart of a pressure pipe tee extrusion method according to an embodiment of the present invention. Figure 3 schematically illustrates a flow chart of the operation of the pressure tube tee extrusion method of an embodiment of the present invention.
Referring to fig. 2 and 3, the method for extrusion forming of the tee of the pressure pipe includes the following steps: s1, using a continuous casting billet as a raw material, and preparing an extrusion billet by adopting a construction forming method; s2, placing the extrusion blank in a combined three-way die, and sequentially extruding the three-way branch pipe and the three-way main pipe by adopting an integrated extrusion forming process to prepare a three-way blank; and S3, demolding the tee-joint-shaped blank by adopting the combined tee-joint mold, and machining to obtain the finished product of the tee joint of the pressure pipe.
The following will describe in detail the respective steps of the three-way extrusion molding method for pressure pipes according to the embodiment of the present invention with reference to the specific embodiments and the accompanying drawings.
And S1, using a continuous casting billet as a raw material, and manufacturing an extrusion billet by adopting a construction forming method.
First, step S1 further includes: and sequentially carrying out electric smelting rough smelting, external refining and continuous casting forming on the scrap steel to obtain the continuous casting billet.
First, the electric smelting roughing includes: scrap steel is smelted by an electric furnace to produce raw steel and dephosphorized.
Optionally, the electric furnace is an electric arc furnace or an oxygen converter, and the specific specification can be selected according to actual needs, for example, the electric furnace can adopt a 180t electric arc furnace.
Secondly, the external refining comprises the following steps: refining the raw materials subjected to electric smelting and rough smelting by adopting a Vacuum Oxygen Decarburization (VOD), ladle refining (LF) and a Vacuum Degassing (VD) in sequence.
It is understood that the vacuum oxygen decarburization process may include: blowing oxygen into the top of the molten steel surface in the vacuum tank for decarburization, blowing argon from the bottom of the steel ladle to promote the circulation of the molten steel so as to supplement the decarburization reaction near the nozzle, prevent the local oxidation of chromium, and simultaneously stirring the molten steel by argon in vacuum so as to promote the floating of nonmetallic inclusions.
The ladle refining method may include: and (3) heating by using a graphite electrode in a reducing atmosphere in a submerged arc manner, blowing argon by using the air brick, stirring, degassing and refining the high-alkalinity slag, thereby removing hydrogen, oxygen, sulfur and impurities in the steel.
Alternatively, the specific specification of the ladle refining furnace adopted by the ladle refining method can be selected according to actual needs, and for example, a 180t LF refining furnace can be adopted for alloying and desulfurization.
It should be noted that the VD type vacuum processing furnace does not have a heating function, and needs to be used in cooperation with an LF furnace. Therefore, the vacuum degassing method may be performed immediately after the ladle refining method.
The vacuum degassing method may include: degassing of molten steel is achieved under vacuum conditions.
According to the specific embodiment, in the continuous casting billet manufacturing process, the external refining method of VOD + LF + VD is comprehensively adopted, and the high-purity casting is obtained according to the smelting process routes of raw material rough smelting, VOD refining vacuum decarburization, LF furnace refining desulfurization, VD refining degassing and the like. The quality requirements of the prepared high-purity castings comprise: no casting defects such as slag inclusion, air holes, cracks and the like, and qualified secondary ultrasonic flaw detection and performance detection.
Thirdly, after the external refining method, a continuous casting forming process is carried out to prepare the continuous casting blank raw material required by the invention.
By the embodiment of the invention, the continuous casting forming process can comprise the following steps: and (3) adopting a vertical bending type continuous casting machine and combining an electromagnetic stirring complete device to carry out continuous casting forming.
In the continuous casting process, different types of electromagnetic stirring complete devices are installed at different positions of a continuous casting machine in the electromagnetic stirring process, the generated electromagnetic force is used for strengthening the flowing of the molten steel in the continuous casting billet, and the electromagnetic stirring device has the stirring effect in the molten steel without contacting the molten steel, so that the quality of the continuous casting billet is obviously improved.
Optionally, the electromagnetic stirring complete set of apparatus has a set current of 1120A and a set frequency of 2.7HZ during the electromagnetic stirring process, and based on this setting, the columnar crystal structure during the solidification of molten steel is broken during the continuous casting process, so that a finer and more uniform equiaxial crystal structure can be obtained. It is understood that in other embodiments, the parameters of the apparatus in the electromagnetic stirring process can be selected according to actual needs, and the specific invention is not limited thereto.
The manufacturing method of the raw material continuous casting slab required in the embodiment of the present invention has been completed, and a specific working process of forming the extrusion billet by the building and forming method in step S1 will be described below.
In the embodiment of the invention, a high-purity stainless steel continuous casting blank is used as a raw material, and an extrusion blank is manufactured by a construction forming method.
Alternatively, the continuous casting billet adopts high-quality 316H material.
Fig. 4 is a flow chart schematically illustrating the construction forming operation in the method for three-way extrusion forming of pressure pipes according to the embodiment of the present invention.
As shown in fig. 4, in the embodiment of the present invention, in step S1, the forming method may sequentially include: the method comprises the following steps of continuous casting blank sawing, surface milling and grinding, surface cleaning treatment, stacking, vacuum sealing and welding, welding seam polishing and heating before forging, high-temperature high-pressure large-deformation forging and pressing, high-temperature diffusion, multidirectional forging, chamfering, rounding, upsetting, punching and saddle reaming.
Specifically, firstly, since the continuous casting slab is a solid continuous casting round bar, the continuous casting slab needs to be sawed to a preset blanking length. The preset blanking length is the length set by the primary design.
The additional stress added to the edge of the blank by the sawing blanking is small, so that the stress control during the subsequent vacuum sealing welding of the blank is very facilitated.
The surface milling process may include, for example: and processing the blank sawed by the continuous casting blank into a flat and smooth surface by adopting a rotary milling cutter.
Surface cleaning treatments may include, for example: and carrying out surface treatment on the blank subjected to surface milling to ensure that the surface of the blank reaches the preset roughness and cleanliness.
The vacuum sealing may include, for example: and sealing and welding the continuous casting blank by using a vacuum electron beam welding machine.
Further, after vacuum sealing, continuous forging is required.
Alternatively, the pressure pipe billet is subjected to cogging forging and upsetting, punching and mandrel drawing by using a large-scale press, and the forged billet is subjected to rough machining by using a large-scale vertical milling machine to be extruded into a cylindrical billet, thereby manufacturing an extruded billet. The size of the press may be 125MN, for example.
The extrusion billet finally manufactured in the step is a forging round billet, and as shown in figure 1, the specific size can be, for example, the diameter phi 1247 +/-2 mm and the length 1987 +/-2 mm.
And S2, placing the extrusion blank in a combined three-way die, and sequentially extruding the three-way branch pipe and the three-way main pipe by adopting an integrated extrusion forming process to prepare a three-way blank.
In the step, the integral tee joint extrusion forming process is adopted, so that the blank with the shape of the tee joint of the complete pressure pipe in a non-welding seam form can be manufactured.
Specifically, adopt integration extrusion forming technology to extrude tee bend branch pipe and tee bend person in charge in proper order, include: and (3) driving an extrusion punch head to be sequentially manufactured into a tee-shaped blank through a forward extrusion process and a backward extrusion process by the extrusion blank through an extruder.
The forward extrusion process can extrude the required three-way branch pipe, and the backward extrusion process can extrude the required three-way main pipe, so that the three-way blank is integrally extruded. The extruder used may be a large extruder having a size of 500MN or more, for example.
It is noted that the extrusion punch of the present invention may be a one-piece extrusion punch to accomplish both the forward extrusion process and the backward extrusion process. Alternatively, the extrusion punch may be a detachable punch, for example, a detachable forward extrusion punch and a detachable backward extrusion punch may be included to perform the forward extrusion process and the backward extrusion process, respectively.
Figure 5 is a schematic diagram showing an extrusion process in a pressure pipe tee extrusion method according to an embodiment of the present invention.
In the embodiment of the present invention, as shown in fig. 5, the integral extrusion punch is composed of a solid cylindrical shaft and a cylindrical boss located at one end of the cylindrical shaft and having a diameter larger than that of the cylindrical shaft, wherein the cylindrical boss serves as a forward extrusion punch 41, and the cylindrical shaft serves as a backward extrusion punch 42. And the diameter of the cylindrical boss is the same as that of the inner wall of the main pipe of the cavity of the combined three-way die, so that the sizes of the forward extrusion punch 41 and the main pipe of the cavity are matched.
Wherein, the positive extrusion process specifically comprises: and (3) extruding and upsetting the extruded blank 3 by using the forward extrusion punch 41, so that the extruded blank 3 is filled in a branch pipe cavity of the combined three-way die 2.
Referring to fig. 5, in this step, the extruder is controlled to drive the forward extrusion punch 41 to move downward, the extrusion blank 3 is a straight tube blank and is placed in the combined three-way die 2, at this time, the forward extrusion punch 41 slowly enters the main pipe position at the upper part of the combined three-way die 2 to press and extrude the blank, along with the slow operation of the forward extrusion punch 41, the pressure borne by the upper surface of the straight tube blank gradually increases, the straight tube blank is shunted along the branch pipes at the two sides of the lower part of the combined three-way die 2, so that the straight tube blank can be gradually filled into the branch pipes at the two sides, and after the branch pipes at the two sides are completely filled, the press machine can be stopped, so that the straight tube blank is pressed and formed into a special-shaped tube blank with a complete three-way branch pipe shape.
It can be understood that the forward extrusion punch 41 of this step causes the inside of the cavity at the upper main pipe position of the three-way die 2 to fail to reach the full shape during the forward extrusion process. Therefore, the invention also needs to carry out a backward extrusion process.
Specifically, the backward extrusion process comprises: and reversely extruding the extrusion blank 3 into the combined three-way die 2 by using the reverse extrusion punch 42 until the extrusion blank 3 is filled in the main pipe cavity of the combined three-way die 2.
With continuing reference to fig. 5, in this step, because the straight pipe blank is press-formed into the special-shaped pipe blank having the shape of the complete three-way branch pipe in the forward extrusion process, however, a large amount of gaps still exist inside the upper main pipe of the combined three-way die 2 and are not yet filled up, the invention adopts the extrusion punch to perform backward extrusion, that is, uses the backward extrusion punch 42 in the extrusion punch to make the special-shaped pipe blank and the upper end of the main pipe of the combined three-way die 2 flush with each other, so that the extrusion blank 3 is filled up in the inner wall of the main pipe cavity at the upper part of the combined three-way die 2, and the special-shaped pipe blank is press-formed into the blank having the shape of the complete three-way branch pipe and the main pipe.
Fig. 5 is a view schematically showing the construction of a three-way die for assembling in the method for extrusion forming a pressure pipe tee according to the embodiment of the present invention.
As shown in fig. 5, the extrusion punch may also be a detachable punch, which may include, for example, a detachable forward extrusion punch 410 and a detachable reverse extrusion punch 420. Wherein the detachable forward extrusion punch 410 completes the operation of the forward extrusion punch 41 in the integral extrusion punch, and the detachable backward extrusion punch 420 completes the operation of the backward extrusion punch 42 in the integral extrusion punch. For the sake of brevity, the specific extrusion process refers to the specific operation of the integral extrusion punch, and is not described in detail herein.
In the embodiment of the present invention, before placing the extrusion blank in the combined three-way die, the method further includes: the extruded billet is heated to 1100-1200 ℃. The extrusion forming process of the invention specifically adopts hot extrusion forming, and the extrusion of the tee joint can be carried out at a slower deformation rate, so that the extrusion blank can be conveniently pressed and deformed by heating to 1100-1200 ℃, and the temperature is lower when the deformation is finished, so that the crystal grains can not grow excessively.
In addition, in order to improve the quality of the extrusion blank and the extrusion work efficiency, before the extrusion blank is placed in the combined three-way die, the extrusion die further comprises: and uniformly smearing a lubricant on the inner wall of the cavity of the combined three-way die.
Optionally, the forward extrusion process and the backward extrusion process further comprise: the extrusion speed is controlled to be 0.5-2mm/s. It will be appreciated that when the speed is slower during extrusion, the extrusion speed can be further reduced in the event that the pressure reaches a limit. More importantly, the lower extrusion speed can reduce the pressure required by deformation and inhibit the generation of surface folding of the blank.
Optionally, the forward extrusion process and the backward extrusion process further comprise: and controlling the machining allowance of the extruded blank single-side machine to be 10-20mm. According to measurement, the grain size of the tee-joint-shaped blank prepared in the step is ideal, the machining allowance is reasonable, and the control of the external dimension of the tee joint in the subsequent heat treatment and machining processes is facilitated.
The invention combines the construction forming method and the extrusion forming process, the construction forging is prepared by the construction forming method and is used as the extrusion blank, the chemical composition, the mechanical property uniformity and the stability of the construction forging are superior to those of the traditional forging, and the construction forging has great advantages when being used for extruding the blank.
And S3, demolding the tee-joint-shaped blank by adopting the combined tee-joint mold, and machining to obtain the finished product of the tee joint of the pressure pipe.
Fig. 6 is a view schematically showing a structure of a three-way die for pressure pipes according to an embodiment of the present invention.
In order to ensure smooth demolding of the tee-shaped blank due to the complex shape of the tee-joint pipe, as shown in fig. 6, in the step, the combined tee-joint die 2 is of a combined die structure which can be split in the middle, the sheath for fixing the combined tee-joint die 2 is removed firstly after extrusion is completed, and then the combined tee-joint die 2 is disassembled, so that demolding of the tee-joint-shaped blank can be completed.
In the embodiment of the invention, the machining sequentially comprises the following steps: rough machining, solution treatment and finish machining.
It should be noted that, before rough machining, the demolded tee-shaped blank needs to be installed and corrected for subsequent machining.
Specifically, the three-way-shaped blank is fixed on a numerical control boring machine workbench by using a positioning tool clamp, and the positioning reference is corrected to prepare before machining.
Further, the rough machining includes: and sequentially machining the inner hole of the main tee pipe, the inner hole of the branch tee pipe and the residual tee area by adopting a numerical control lathe arranged on a workbench of the numerical control boring machine, wherein the single-side finish machining allowance for keeping the wall thicknesses of the inner hole of the main tee pipe, the inner hole of the branch tee pipe and the residual tee area is not less than 15mm.
Specifically, firstly, the inner hole of the three-way main pipe is machined by a numerically controlled lathe. According to fig. 1, since the inner diameter of the final inner hole of the main pipe can be, for example, phi 1180mm, and the wall thickness can be 35mm, the rough machining of the wall thickness in the process can leave a finishing allowance of, for example, 15mm, that is, the machining inner hole of the process is sized to the diameter phi 1150mm.
Secondly, the inner holes of the three-way branch pipes are machined, and at the moment, the machine tool needs to be adjusted to sequentially add the inner holes of the two branch pipes. According to FIG. 1, the inner diameter of the final product of the inner holes of the two branch pipes can be, for example, phi 670mm, and the wall thickness can be 35mm. The thickness of the rough machined wall in this step may be set to leave a finishing allowance of, for example, 15mm, that is, the inner hole is machined to a diameter of phi 640mm in this step.
Finally, machining the tee joint residual area by using a numerical control lathe, wherein the machining process comprises the following steps: firstly, the positioning tool fixture is used for aligning and positioning the direction, and then the cutter is fed to process the left branch pipe of the tee joint. Because the left branch pipe and the right branch pipe of the pressure pipe tee joint are symmetrically distributed, after the tee joint left branch pipe is machined, the three-way pipe is turned over by 180 degrees, the positioning tool fixture is reused for aligning and orienting, and then the tee joint right branch pipe is machined by feeding.
On this basis, the rough machining of the whole tee piece is completed, and the allowance of the wall thickness can be 15mm. And after the rough machining is finished, carrying out solution treatment on the tee joint blank.
In an embodiment of the present invention, the solution treatment includes: and fully dissolving and heating carbides in the roughly processed extruded blank into an austenitic stainless steel matrix, and then annealing.
Wherein the solution heating further comprises: controlling the temperature rise rate to be not more than 150 ℃/h, heating the roughly processed extruded shape blank to the temperature range of 1060 ℃ +/-10 ℃, and preserving the temperature in the temperature range for at least 2 hours.
It is understood that the heating temperature, the holding time and the heating rate of the step are all limited in order to achieve sufficient solid solution of the carbide in the tee-shaped billet into the austenitic stainless steel matrix. The solid solution heat treatment can re-dissolve the precipitated phase back into austenite to form a supersaturated solution, thereby realizing accurate regulation and control of the structure and performance of the forging.
After the solution treatment, finish machining is needed for removing the reserved machining allowance and machining the tee joint to the size of the drawing.
Further, after finishing, the method further comprises: and polishing the parts which cannot be machined and the parts which do not meet the requirement of surface finish in the tee-joint-shaped blank, and forming the finished product of the pressure pipe tee after the finished product is detected to be qualified.
Based on the pressure pipe tee extrusion forming method, the tee formed by the finally formed pressure pipe tee is tested by a microstructure, and the grain size is 2-3 grade. And areAnd after mechanical property test and sampling at any position of a test piece, the yield strength sigma of the material is measured 0.2 The fluctuation range of (A) is not more than 30MPa, and the fluctuation range of the impact absorption power is not more than 50J. That is, the invention improves the uniformity of the mechanical property of the pressure pipe by the extrusion and machining forming process of the tee joint.
In summary, the embodiments of the present invention provide an extrusion forming method for a pressure pipe tee, which reduces the welding seams of the pressure pipe tee, improves the tensile property of the material and the uniformity of the impact energy, improves the safety under the condition of complex working condition loads, and shortens the manufacturing period.
It should be noted that the implementations not shown or described in the drawings are in a form known to those of ordinary skill in the art. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure. Additionally, while exemplifications of parameters including particular values may be provided herein, it is to be understood that the parameters need not be exactly equal to the respective values, but may be approximated to the respective values within acceptable error margins or design constraints.
It should be further noted that directional terms, such as "upper", "lower", "front", "back", etc., referred to in the embodiments are only directions referring to the drawings. Accordingly, the directional terminology used is intended to be in the nature of words of description rather than of limitation.
And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.
Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (16)
1. The extrusion forming method of the pressure pipe tee joint is characterized by comprising the following steps:
using a continuous casting billet as a raw material, and preparing an extrusion blank by adopting a construction forming method;
heating the extrusion billet to 1100-1200 ℃;
placing the extrusion blank in a combined three-way die, and sequentially extruding the three-way branch pipe and the three-way main pipe by adopting an integrated extrusion forming process to prepare a three-way blank;
demolding the tee-shaped blank by adopting the combined tee-joint mold, and machining to obtain a finished product of the pressure pipe tee joint;
wherein, adopt integration extrusion forming technology to extrude tee bend branch pipe and tee bend person in charge in proper order and make tee bend shape blank, include: the extrusion blank is a forged round blank, and the extrusion blank is made into a tee-shaped blank by driving an extrusion punch through an extruder and sequentially performing a forward extrusion process and a backward extrusion process;
the extrusion punch consists of a solid cylindrical shaft and a cylindrical boss which is positioned at one end of the cylindrical shaft and has a diameter larger than that of the cylindrical shaft, wherein the cylindrical boss is used as a forward extrusion punch, the cylindrical shaft is used as a backward extrusion punch, and the diameter of the cylindrical boss is the same as that of the inner wall of the cavity main pipe of the combined three-way die;
the forward extrusion process comprises:
extruding and upsetting the extruded blank by using the forward extrusion punch to enable the extruded blank to fill a branch pipe cavity of the combined three-way die;
the backward extrusion process comprises the following steps:
reversely extruding the extrusion blank into the combined three-way die by using the reverse extrusion punch until the extrusion blank is full of the main pipe cavity of the combined three-way die;
the forward extrusion process and the backward extrusion process further comprise:
controlling the extrusion speed to be 0.5-2mm/s;
and controlling the machining allowance of the extruded blank single-side machine to be 10-20mm.
2. The three-way extrusion molding method for pressure pipes as claimed in claim 1, wherein the step of forming the extrusion billet by the construction molding method using a continuous casting slab as a raw material further comprises: and sequentially carrying out electric melting rough smelting, external refining and continuous casting forming processes on the scrap steel to obtain the continuous casting billet.
3. The three-way extrusion molding method for pressure pipes according to claim 2, wherein 316H material is used as the continuous casting billet.
4. The pressure pipe three-way extrusion molding method as claimed in claim 2, wherein in the step of subjecting the scrap steel to the electric smelting roughing, the external refining and the continuous casting molding in sequence to produce the continuous casting billet, the external refining comprises: and refining the raw materials subjected to electric smelting rough smelting by sequentially adopting a vacuum oxygen blowing decarburization method, a ladle refining method and a vacuum degassing method.
5. The extrusion forming method of the pressure pipe tee as claimed in claim 2, wherein in the step of subjecting the scrap steel to the electric smelting roughing, the external refining and the continuous casting forming process in sequence to obtain the continuous casting billet, the continuous casting forming process comprises: and (3) adopting a vertical bending type continuous casting machine and combining an electromagnetic stirring complete device to carry out continuous casting forming.
6. The three-way extrusion molding method for pressure pipes as claimed in claim 1, wherein the step of forming the extrusion billet by using a construction and forming method using a continuous casting billet as a raw material comprises the following steps in sequence: the method comprises the following steps of continuous casting blank sawing, surface milling and grinding, surface cleaning treatment, stacking, vacuum sealing and welding, welding seam polishing and heating before forging, high-temperature high-pressure large-deformation forging and pressing, high-temperature diffusion, multidirectional forging, chamfering, rounding, upsetting, punching and saddle reaming.
7. The method for extrusion forming of the tee for pressure pipes as claimed in claim 6, wherein the high temperature high pressure large deformation forging and the multi-directional forging are performed by a press.
8. The method of extrusion forming a pressure tube tee as claimed in claim 1, further comprising, prior to placing said extrusion billet in a unitized tee die:
and uniformly smearing a lubricant on the inner wall of the cavity of the combined three-way die.
9. The method for extrusion forming of a tee for pressure pipes as claimed in claim 1, wherein the step of de-molding the tee shaped blank using a modular tee die comprises:
the combined type three-way die is split in the middle, after extrusion is completed, the sheath used for fixing the combined type three-way die is removed, and then the combined type three-way die is disassembled, so that demoulding of the three-way-shaped blank is completed.
10. The extrusion method for forming a pressure tube tee as claimed in claim 1, wherein the step of machining to obtain the finished pressure tube tee includes rough machining, solution treatment and finish machining in this order.
11. The method of extrusion forming a pressure tube tee as set forth in claim 10, further including, prior to said roughing:
and fixing the tee-joint-shaped blank on a workbench of a numerical control boring machine by using a positioning tool clamp, and correcting a positioning reference.
12. The method of extrusion of a pressure tube tee as set forth in claim 11 wherein said roughing includes:
and sequentially machining the inner hole of the main tee pipe, the inner hole of the branch tee pipe and the residual tee area by adopting a numerical control lathe arranged on the workbench of the numerical control boring machine, wherein the single-side finish machining allowance of the wall thickness of the reserved inner hole of the main tee pipe, the reserved inner hole of the branch tee pipe and the residual tee pipe area is not less than 15mm.
13. The method for extrusion forming of a pressure tube tee as claimed in claim 12, wherein said machining the tee residual area with a numerically controlled lathe comprises:
firstly, aligning and positioning the direction by using the positioning tool clamp, and then feeding to machine a left branch pipe of the tee joint;
after the three-way left branch pipe is machined, the three-way pipe is turned over by 180 degrees, the positioning tool fixture is used again for aligning and positioning, and then the three-way right branch pipe is machined by feeding.
14. The pressure tube tee extrusion method of claim 10, wherein the solution treatment comprises:
and fully carrying out solid solution heating on carbides in the roughly processed extruded blank to an austenitic stainless steel matrix, and then carrying out annealing treatment.
15. The pressure tube three-way extrusion forming method of claim 14, wherein the solution heating further comprises:
controlling the temperature rise rate to be not more than 150 ℃/h, heating the roughly processed extruded shape blank to the temperature range of 1060 ℃ +/-10 ℃, and preserving the temperature in the temperature range for at least 2 hours.
16. The pressure tube tee extrusion forming method as recited in claim 10, further comprising, after said finishing:
and polishing the parts which cannot be machined and the parts which do not meet the requirement of surface finish in the tee-joint-shaped blank, and forming the finished product of the pressure pipe tee after the finished product is detected to be qualified.
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| CN102699176A (en) * | 2012-05-09 | 2012-10-03 | 佛山市顺德区燉煌五金塑料实业有限公司 | Tee joint forming supporting auxiliary apparatus |
| CN105215252A (en) * | 2015-10-23 | 2016-01-06 | 北京机电研究所 | The forming technology of the mould of preform 45 ° of skew T jumping-up parts, method and 45 ° of skew Ts |
| CN107876673A (en) * | 2016-09-30 | 2018-04-06 | 上海昌强工业科技股份有限公司 | A kind of Y-type three way type multi-ram forging technique and mould |
| CN107876677A (en) * | 2016-09-30 | 2018-04-06 | 上海昌强重工机械有限公司 | A kind of large bevel tee die forging production technology and mould |
| CN106623466A (en) * | 2017-01-07 | 2017-05-10 | 河北宏润核装备科技股份有限公司 | Nuclear main pump shell hot extrusion forming technology |
| CN107671216B (en) * | 2017-09-08 | 2020-05-05 | 中国科学院金属研究所 | Hourglass-shaped metal construction forming method |
| CN110565012B (en) * | 2019-07-19 | 2021-08-10 | 浙江青山钢铁有限公司 | Continuous casting manufacturing method of ultra-high chromium ferrite stainless steel |
| CN210849239U (en) * | 2019-09-29 | 2020-06-26 | 艾锑威（上海）材料科技有限公司 | Tee bend pipe fitting anchor clamps for machine tooling |
| CN111570695A (en) * | 2020-05-25 | 2020-08-25 | 上海电机学院 | Large three-way die forging device for power station equipment and die forging method thereof |
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