阅读说明：本技术 一种预应变强化波纹管的成型方法 (Forming method of pre-strain reinforced corrugated pipe ) 是由 闫廷来 李�杰 刘海威 杨玉强 李瑞琴 于 2020-06-24 设计创作，主要内容包括：一种预应变强化波纹管的成型方法,对多层波纹管管坯进行预应变强化和液压强化二次强化成型,在预应变强化时,对波纹管管坯进行均匀的轴向拉伸和/或周向拉伸,得到预应变强化波纹管管坯,利用波纹管成型装置对预应变强化波纹管管坯纵向液压成形波纹,完成二次强化。本方法提高大直径波纹管的材料强度,节省成本。(A method for forming a pre-strain reinforced corrugated pipe comprises the steps of carrying out pre-strain reinforcement and hydraulic reinforcement secondary reinforcement forming on a multi-layer corrugated pipe blank, carrying out uniform axial stretching and/or circumferential stretching on the corrugated pipe blank during pre-strain reinforcement to obtain a pre-strain reinforced corrugated pipe blank, and carrying out longitudinal hydraulic forming corrugation on the pre-strain reinforced corrugated pipe blank by using a corrugated pipe forming device to complete secondary reinforcement. The method improves the material strength of the large-diameter corrugated pipe and saves the cost.)

1. A forming method of a pre-strain reinforced corrugated pipe is characterized by comprising the following steps: carrying out secondary strengthening forming of pre-strain strengthening and hydraulic strengthening on the multi-layer corrugated pipe blank, carrying out uniform axial stretching and/or circumferential stretching on the corrugated pipe blank during pre-strain strengthening to obtain a pre-strain strengthened corrugated pipe blank, and carrying out longitudinal hydraulic forming corrugation on the pre-strain strengthened corrugated pipe blank by using a corrugated pipe forming device to finish secondary strengthening.

2. The method of claim 1, wherein the pre-strain reinforced bellows comprises: and during axial stretching, the corrugated pipe blank is axially stretched from the two axial ends of the corrugated pipe blank according to opposite directions and the same tensile force.

3. The method of claim 1, wherein the pre-strain reinforced bellows comprises: the axial both ends of bellows pipe are removable connection respectively on the flange subassembly, realize axial tension through the flange subassembly at mechanical pulling both ends.

4. The method of claim 1, wherein the pre-strain reinforced bellows comprises: during circumferential stretching, two cylindrical pulling pieces are respectively and axially arranged from two sides in the corrugated pipe blank, the two cylindrical pulling pieces are attached to the inner surface of the corrugated pipe blank to stretch the corrugated pipe blank, and the two cylindrical pulling pieces are mechanically pulled to perform circumferential stretching according to the same pulling force in opposite directions.

Technical Field

The invention belongs to the field of pipeline compensation, and particularly relates to a forming method of a pre-strain reinforced corrugated pipe.

Background

The whole process of the hydraulic forming of the corrugated pipe is that the pipe blank of the corrugated pipe generates plastic yield under the action of forming force, a press slide block descends, and after the device is closed, the forming is finished after elastic rebound is released, as shown in figure 1.

After the corrugated pipe is shaped, the strength of the material is improved, the material body is strengthened, compared with a pipe blank before shaping, the yield strength of the material is improved, which is a result of typical material processing hardening, and fig. 2 shows that after the material is subjected to certain shaping deformation, the yield strength is improved from a point A to a point B, and the overall strength is increased.

For the corrugated pipe with small diameter, the plastic strain is large, the formed strength is high, for the corrugated pipe with large diameter, the plastic strain is limited, so the strength improvement of the formed material is limited, the influence action of the corrugated pipe plasticity on the strength can be indirectly reflected by a variable eta, eta =1+h/DH is the corrugated pipe wave height, D is the corrugated pipe diameter, and the larger the diameter is, the smaller the effect of plastic strain strengthening on the corrugated pipe strength is. Taking a stainless steel 304 material as an example, the yield strength given by the standard is 205MPa, the yield strength of the DN300 corrugated pipe after being formed is 417MPa, and the yield strength of the DN2000 corrugated pipe after being formed is 330 MPa.

Disclosure of Invention

In order to solve the technical problems, the invention provides a forming method of a pre-strain reinforced corrugated pipe, so that the material strength of a large-diameter corrugated pipe is improved, and the cost is saved.

In order to realize the technical purpose, the adopted technical scheme is as follows: a method for forming a pre-strain reinforced corrugated pipe comprises the steps of carrying out pre-strain reinforcement and hydraulic reinforcement secondary reinforcement forming on a multi-layer corrugated pipe blank, carrying out uniform axial stretching and/or circumferential stretching on the corrugated pipe blank during pre-strain reinforcement to obtain a pre-strain reinforced corrugated pipe blank, and carrying out longitudinal hydraulic forming corrugation on the pre-strain reinforced corrugated pipe blank by using a corrugated pipe forming device to complete secondary reinforcement.

And during axial stretching, the corrugated pipe blank is axially stretched from the two axial ends of the corrugated pipe blank according to opposite directions and the same tensile force.

The axial both ends of bellows pipe are removable connection respectively on the flange subassembly, realize axial tension through the flange subassembly at mechanical pulling both ends.

During circumferential stretching, two cylindrical pulling pieces are respectively and axially arranged from two sides in the corrugated pipe blank, the two cylindrical pulling pieces are attached to the inner surface of the corrugated pipe blank to stretch the corrugated pipe blank, and the two cylindrical pulling pieces are mechanically pulled to perform circumferential stretching according to the same pulling force in opposite directions.

The invention has the beneficial effects that: the formed corrugated pipe material is subjected to secondary strengthening by adding the pre-strain process of the corrugated pipe blank, and the strength of the formed material can be improved for the large-caliber corrugated pipe, so that the allowable design stress is improved, and the purpose of reducing the material usage amount is achieved.

Drawings

FIG. 1 is a schematic diagram of a hydraulic apparatus of the prior art;

FIG. 2 is a graph of the effect of plastic deformation on material strength after forming in the prior art;

FIG. 3 is a schematic axial drawing of a bellows tube blank pre-strain strengthened in accordance with the present invention;

FIG. 4 is a schematic view of the circumferential stretching of the bellows blank of the present invention with pre-strain strengthening;

FIG. 5 is a schematic diagram of the strength enhancement of the pre-strain-strengthened bellows of the present invention;

FIG. 6 is a schematic of the process of the present invention;

in the figure: 1. the device comprises an oil press, 2, an upper die cover, 3, a middle die plate, 4, a corrugated pipe blank, 5, a lower die cover, 6, a hydraulic pump, 7 and an initial cushion block.

Detailed Description

A method for forming a pre-strain reinforced corrugated pipe comprises the steps of carrying out pre-strain reinforcement and hydraulic reinforcement secondary reinforcement forming on a multi-layer corrugated pipe blank, carrying out uniform axial stretching and/or circumferential stretching on the corrugated pipe blank during pre-strain reinforcement to obtain a pre-strain reinforced corrugated pipe blank, and carrying out longitudinal hydraulic forming corrugation on the pre-strain reinforced corrugated pipe blank by using a corrugated pipe forming device to complete secondary reinforcement. If the corrugated pipe with the diameter of 4m needs to be manufactured, a pipe blank with the diameter of 3.8m can be used for forming, so that the material can be saved, and the yield strength of the corrugated pipe is higher than that of the corrugated pipe formed by one-step forming by using the pipe blank with the diameter of 4 m.

The corrugated pipe blank is firstly strengthened by adopting a mechanical stretching method, including strengthening of a welding seam, and the corrugated pipe blank can be strengthened by adopting two stretching directions, namely the axial direction of the corrugated pipe blank and the circumferential direction of the corrugated pipe blank, as shown in figures 3 and 4. And (3) stretching by using a force F, wherein the stretching deformation amount is delta x, performing secondary strengthening of hydraulic forming on the corrugated pipe blank subjected to pre-strain strengthening, wherein the formed corrugated pipe has higher strength, and the material strength is improved from the body strength A point to the body strength C point, as shown in fig. 5.

And during axial stretching, longitudinally stretching the corrugated pipe blank from the two axial ends of the corrugated pipe blank according to opposite directions and the same tensile force.

The axial both ends of bellows pipe are removable connection respectively on the flange subassembly, realize vertical tensile through the flange subassembly at mechanical pulling both ends. The flange assembly comprises an upper flange and a lower flange, the lower flange is of a lower cylindrical structure, the upper portion of the lower flange is of a disc-shaped structure, a connecting hole is formed in the disc-shaped structure, the diameter of an inner cavity of the cylindrical structure of the lower flange is equal to the outer diameter of a corrugated pipe ring, the lower flange is sleeved on the outer side of the corrugated pipe ring, the upper flange is integrally formed by the lower cylindrical structure and the upper disc-shaped structure, the disc-shaped structure is provided with the connecting hole corresponding to the lower flange disc-shaped structure, the outer diameter of the lower cylindrical structure of the upper flange is consistent with the inner diameter of a corrugated pipe blank, the corrugated pipe blank is clamped between the flange assemblies, and axial.

During circumferential stretching, two cylindrical pulling pieces are respectively and axially arranged from two sides in the corrugated pipe blank, the two cylindrical pulling pieces are attached to the inner surface of the corrugated pipe blank to stretch the corrugated pipe blank, and the two cylindrical pulling pieces are mechanically pulled to perform circumferential stretching according to the same pulling force in opposite directions. The length of the cylindrical pulling piece is longer than that of the corrugated pipe blank, and the two ends of the cylindrical pulling piece are mechanically fixed to stretch in the transverse stretching process, so that the cylindrical pulling piece is stressed more uniformly and stretched more reasonably.

As shown in figure 1, the hydraulic multi-wave one-step forming device for the corrugated pipe mainly comprises an oil press, an upper die cover, a middle die plate, a lower die cover, a cushion block, a corrugated pipe blank and a hydraulic pump, wherein tap water is used as a forming medium. The upper sliding blocks of the oil press are fixed, and initial cushion blocks are added between the middle dies and the upper and lower die covers to prevent the middle dies from sliding off. And (3) filling water into the inner cavity of the corrugated pipe blank, pressurizing, and enabling the corrugated pipe material to generate plastic deformation under the action of internal pressure. When the plastic deformation reaches a certain degree, the initial cushion block is removed, the pressure is continuously charged, meanwhile, the oil press applies axial displacement to the corrugated pipe, until the dies are mutually attached, and the corrugated pipe is molded.

As shown in FIG. 6, the invention relates to a pre-strain reinforced corrugated pipe, which is characterized in that the integral reinforcement of a corrugated pipe blank (including a pipe blank welding seam) is realized by adding a pre-strain process of the corrugated pipe blank, so that the formed corrugated pipe can be reinforced for the second time, the material strength of the formed corrugated pipe with a large caliber can be improved, the allowable design stress can be improved, and the purpose of saving the material usage amount can be achieved. The method comprises three pre-strain strengthening methods, namely: the corrugated pipe blank is strengthened through axial uniform stretching; the second method comprises the following steps: reinforcing the corrugated pipe blank by circumferentially and uniformly stretching; the third method comprises the following steps: the corrugated pipe blank is strengthened by axial uniform stretching and circumferential uniform stretching. And (3) according to the direction of the corrugated pipe to be pressurized, selecting a proper method to strengthen the pre-strain corrugated pipe blank.