Forming process of titanium alloy corrugated pipe for compensator

Abstract

The invention relates to a forming process of a titanium alloy corrugated pipe for a compensator. The forming process comprises the following steps: (1) manufacturing a pipe blank; (2) loading into a mold; (3) annularly heating, rotating the mold and the titanium alloy pipe blank, and forming annular corrugations on the surface of the pipe blank by adopting a roller; (4) repeating the step (3) to form a second annular corrugation; (5) repeating the step (3) to form a third annular corrugation; (6) forming a set number of annular corrugations on the surface of the titanium alloy pipe blank according to design requirements; and (7) obtaining a titanium alloy corrugated pipe finished product. A corrugated pipe forming machine, a roller, a combined mold, an oil press and an electric heating coil are mainly adopted for locally and annularly heating a pipe blank, the roller is adopted for extruding the pipe blank, and meanwhile pressure is applied to the two ends of the pipe blank. The forming effect is better, the forming process is simplified, the production cost and the manufacturing difficulty of the product are reduced, and meanwhile the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy bellows technology, and in particular to a forming process for titanium alloy bellows used in compensators. Background Technology

[0002] Chinese patent CN1193839C discloses a method for superplastic forming of titanium alloy corrugated pipes, mainly comprising the following steps: a. Preparing a tube blank: a seamless or welded titanium alloy tube is made into a sealed tube blank, with an air inlet at one end; b. Heating process: the tube blank is placed into a multi-layer mold, and then heated to the superplastic forming temperature of titanium alloy, 650–1000℃; c. Expansion process: gas is injected into the tube blank at a pressure of 0.1–1 MPa, causing the tube blank to expand outwards; d. Mold closing process: a compressive load is applied axially to the mold, causing the modules to close; e. Forming process: the air pressure is further increased into the tube blank, reaching a pressure of 1.5–3.0 MPa, ensuring the tube blank is fully filled into the mold, and finally, the tube blank is cooled and demolded to obtain the finished product. The above method involves high forming temperatures and pressures, requiring sophisticated processing equipment, resulting in high production costs, complex processes, difficult product manufacturing, and low production efficiency.

[0003] Chinese patent CN104525660B discloses a current-assisted thermoforming apparatus and method for titanium alloy bellows. The apparatus includes: positive and negative electrodes tightly fitted onto the upper and lower ends of a cylindrical blank; a low-voltage, high-current power supply connected to the positive and negative electrodes via wires; a gas cylinder connected to a gas guide pipe on the cylindrical blank via a gas pipe; and a forming mold placed on the working platform of a press. The method includes: Step 1: Fabricating the cylindrical blank; Step 2: Mold mounting; Step 3: Equipment installation; Step 4: Forming the bellows; Step 5: Unloading; and Step 6: Post-processing. This method also suffers from high production costs, complex processes, difficult product manufacturing, and low production efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a forming process for titanium alloy bellows for compensators that reduces costs, simplifies the process, achieves good forming results, and increases production efficiency.

[0005] The objective of this invention is achieved by adopting the following technical solution:

[0006] A forming process for a titanium alloy bellows for a compensator includes the following steps:

[0007] (1) The titanium alloy sheet is rolled into a cylindrical shape by a plate rolling machine, and the gap of the cylinder is welded and then shaped to obtain a cylindrical tube blank.

[0008] (2) The titanium alloy tube blank is loaded into the corrugated tube forming mold. The mold is equipped with extrusion forming rollers, which can rotate relative to the mold and the titanium alloy tube blank.

[0009] (3) The titanium alloy tube blank is circumferentially heated and the mold and titanium alloy tube blank are rotated. At the same time, the roller is radially displaced to squeeze the inner surface of the titanium alloy tube blank until the surface of the titanium alloy tube blank is completely in contact with the U-shaped groove of the mold, so that the first annular ripple is formed on the surface of the titanium alloy tube blank.

[0010] (4) Displace the roller axially by the set length, i.e. the design pitch of the bellows, and then repeat step (3) to form a second annular corrugation on the surface of the titanium alloy tube blank.

[0011] (5) Make the roller axially displace by the set length again, and then repeat step (3) to form a third annular ripple on the surface of the titanium alloy tube blank.

[0012] (6) According to the design requirements, a set number of annular corrugations are formed on the surface of the titanium alloy tube blank;

[0013] (7) Cut off the excess part of the titanium alloy tube blank to obtain a corrugated tube of the specified size. Then, after cleaning and surface treatment, the finished titanium alloy corrugated tube is obtained.

[0014] As a preferred technical solution of the present invention, step (3) uses an electric heating coil to perform circumferential heating on the titanium alloy tube blank in sections. After the electric heating coil is started by the power control device, the temperature of the corresponding part of the titanium alloy tube blank is gradually increased according to the heating curve.

[0015] As a preferred embodiment of the present invention, when the temperature of the titanium alloy tube blank reaches a set value, the rollers are used to press the inner surface of the titanium alloy tube blank.

[0016] As a preferred embodiment of the present invention, the temperature of the titanium alloy tube blank is set to 400-650℃.

[0017] As a preferred embodiment of the present invention, the rollers simultaneously apply pressure to both ends of the titanium alloy tube blank while extruding it.

[0018] As a preferred embodiment of the present invention, the titanium alloy tube blank and the corrugated pipe forming mold are mounted on a hydraulic press platform, and pressure is applied to both ends of the tube blank by the hydraulic press.

[0019] As a preferred embodiment of the present invention, pressure is applied to both ends of the titanium alloy tube blank through a screw and nut device.

[0020] As a preferred embodiment of the present invention, the pressure holding time is 3-5 minutes.

[0021] As a preferred embodiment of the present invention, the extrusion forming roller is provided with two corrugated convex rings.

[0022] As a preferred embodiment of the present invention, the chemical composition of the titanium alloy plate is: Fe≤0.05, C≤0.08, O≤0.09, N≤0.03, H≤0.0075;

[0023] The corrugated pipe forming mold is composed of two semi-circular mold pieces; the extrusion forming roller is connected and fixed to the corrugated pipe forming machine.

[0024] The beneficial effects of the present invention are as follows: Compared with the prior art, the present invention mainly uses a corrugated tube forming machine, extrusion forming rollers, combined molds, hydraulic press and electric heating coils. By circumferentially heating the titanium alloy tube blank in sections, when the tube blank temperature reaches the set value, the rollers are used to extrude the inner surface of the titanium alloy tube blank, and pressure is applied to both ends of the titanium alloy tube blank at the same time.

[0025] This invention is suitable for forming large-diameter or thick-walled titanium alloy tube blanks, resulting in better forming performance. This invention not only simplifies the forming process and eliminates the need for high-pressure gas equipment, making the entire process safer and more reliable, but also reduces production costs and manufacturing difficulty while improving production efficiency. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments:

[0027] A forming process for a titanium alloy bellows for a compensator includes the following steps:

[0028] (1) The titanium alloy sheet is rolled into a cylindrical shape by a plate rolling machine, and the gap of the cylinder is welded and then shaped to obtain a cylindrical tube blank.

[0029] (2) The titanium alloy tube blank is loaded into the corrugated tube forming mold. The mold is equipped with extrusion forming rollers, which can rotate relative to the mold and the titanium alloy tube blank.

[0030] (3) The titanium alloy tube blank is circumferentially heated and the mold and titanium alloy tube blank are rotated. At the same time, the roller is radially displaced to squeeze the inner surface of the titanium alloy tube blank until the surface of the titanium alloy tube blank is completely in contact with the U-shaped groove of the mold, so that the first annular ripple is formed on the surface of the titanium alloy tube blank.

[0031] (4) Displace the roller axially by the set length, i.e. the design pitch of the bellows, and then repeat step (3) to form a second annular corrugation on the surface of the titanium alloy tube blank.

[0032] (5) Make the roller axially displace by the set length again, and then repeat step (3) to form a third annular ripple on the surface of the titanium alloy tube blank.

[0033] (6) According to the design requirements, a set number of annular corrugations are formed on the surface of the titanium alloy tube blank;

[0034] (7) Cut off the excess part of the titanium alloy tube blank to obtain a corrugated tube of the specified size. Then, after cleaning and surface treatment, the finished titanium alloy corrugated tube is obtained.

[0035] In this embodiment, step (3) uses an electric heating coil to circumferentially heat the titanium alloy tube blank in sections. After the electric heating coil is started by the power control device, the temperature of the corresponding part of the titanium alloy tube blank is gradually increased according to the temperature rise curve.

[0036] When the temperature of the titanium alloy tube blank reaches a set value, the rollers press against the inner surface of the titanium alloy tube blank; the set temperature of the titanium alloy tube blank is 400-650℃. While the rollers are pressing the titanium alloy tube blank, pressure is simultaneously applied to both ends of the titanium alloy tube blank.

[0037] The titanium alloy tube blank and the corrugated pipe forming die are mounted on a hydraulic press platform, and pressure is applied to both ends of the tube blank via the hydraulic press. Alternatively, pressure can be applied to both ends of the titanium alloy tube blank via a lead screw and nut device. The pressure is held for 3-5 minutes.

[0038] In a preferred embodiment, for thin-walled titanium alloy tube blanks, the extrusion forming roller is provided with two corrugated convex rings. Through the extrusion process of this roller, two annular corrugations can be formed on the surface of the titanium alloy tube blank in one rolling process. This technical solution can increase the production efficiency of the product to twice that of the previous method.

[0039] The chemical composition of the titanium alloy sheet of the present invention is: Fe≤0.05, C≤0.08, O≤0.09, N≤0.03, H≤0.0075; the corrugated pipe forming mold is composed of two semi-circular molds; the extrusion forming roller is connected and fixed to the corrugated pipe forming machine.

[0040] The above embodiments are merely illustrative of the concept and technical features of the present invention, and are intended to enable those skilled in the art to understand the technical solutions and implementation methods of the invention. They should not be construed as limiting the scope of protection of the present invention. All equivalent substitutions or changes made according to the technical solutions of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A forming process for a titanium alloy bellows for compensators, characterized in that... The process includes the following steps: (1) rolling titanium alloy sheet into a cylindrical shape using a plate rolling machine, welding the gaps in the cylinder and then straightening it to obtain a cylindrical tube blank; (2) The titanium alloy tube blank is loaded into the corrugated tube forming mold. The mold is equipped with extrusion forming rollers, which can rotate relative to the mold and the titanium alloy tube blank. (3) The titanium alloy tube blank is circumferentially heated and the mold and titanium alloy tube blank are rotated. At the same time, the roller is radially displaced to squeeze the inner surface of the titanium alloy tube blank until the surface of the titanium alloy tube blank is completely in contact with the U-shaped groove of the mold, so that the first annular ripple is formed on the surface of the titanium alloy tube blank. (4) Displace the roller axially by the set length, i.e. the design pitch of the bellows, and then repeat step (3) to form a second annular corrugation on the surface of the titanium alloy tube blank. (5) Make the roller axially displace by the set length again, and then repeat step (3) to form a third annular ripple on the surface of the titanium alloy tube blank. (6) According to the design requirements, a set number of annular corrugations are formed on the surface of the titanium alloy tube blank; (7) Cut off the excess part of the titanium alloy tube blank to obtain a corrugated tube of the specified size. Then, after cleaning and surface treatment, the finished titanium alloy corrugated tube is obtained.

2. The forming process of the titanium alloy bellows for compensators according to claim 1, characterized in that: In step (3), the titanium alloy tube blank is heated in sections by an electric heating coil. After the electric heating coil is started by the power control device, the temperature of the corresponding part of the titanium alloy tube blank is gradually increased according to the temperature rise curve.

3. The forming process of the titanium alloy bellows for compensators according to claim 2, characterized in that: When the temperature of the titanium alloy tube blank reaches the set value, the rollers press against the inner surface of the titanium alloy tube blank.

4. The forming process of the titanium alloy bellows for compensators according to claim 3, characterized in that: The set temperature of the titanium alloy tube blank is 400-650℃.

5. The forming process of the titanium alloy bellows for compensators according to claim 3, characterized in that: While the rollers extrude the titanium alloy tube blank, pressure is applied simultaneously to both ends of the titanium alloy tube blank.

6. The forming process of the titanium alloy bellows for compensators according to claim 5, characterized in that: The titanium alloy tube blank and the corrugated pipe forming mold are mounted on the hydraulic press platform, and pressure is applied to both ends of the tube blank through the hydraulic press.

7. The forming process of the titanium alloy bellows for compensators according to claim 5, characterized in that: Pressure is applied to both ends of the titanium alloy tube blank via a screw and nut assembly.

8. The forming process of the titanium alloy bellows for compensators according to claim 6 or 7, characterized in that: The pressure is maintained for 3-5 minutes.

9. The forming process of the titanium alloy bellows for compensators according to claim 1, characterized in that: The extrusion forming roller has two corrugated convex rings.

10. The forming process of the titanium alloy bellows for compensators according to claim 1, characterized in that: The chemical composition of the titanium alloy sheet is: Fe≤0.05, C≤0.08, O≤0.09, N≤0.03, H≤0.0075; The corrugated pipe forming mold is composed of two semi-circular mold pieces; the extrusion forming roller is connected and fixed to the corrugated pipe forming machine.