阅读说明：本技术 一种具有波纹结合面的金属复合管三辊斜轧成形方法 (Three-roller skew rolling forming method for metal composite pipe with corrugated joint surface ) 是由 王涛 刘江林 徐志祥 李子轩 程永红 许永明 黄庆学 于 2020-12-09 设计创作，主要内容包括：本发明涉及金属复合管成形技术领域,具体涉及一种具有波纹结合面的金属复合管三辊斜轧成形方法,金属复合管在三辊斜轧机上轧制,三辊斜轧机上设有三个轧辊,轧辊的外表面上从轧辊的小头端至轧辊的大头端依次设置有咬入段、成形段及轧平段,所述轧辊上设有单道成形波纹,成形波纹分布于咬入段的末端与成形段的末端之间,三个轧辊上的成形波纹错距分布,三个轧辊上的成形波纹先后依次与复合管坯的外壁接触。本发明能够利用三辊斜轧机在复合管坯上轧制出一道完整的螺旋波纹,同时将波纹轧制和波纹轧平两种工艺集成在一套轧辊上,减少工艺流程,提高生产效率。(The invention relates to the technical field of metal composite pipe forming, in particular to a three-roller skew rolling forming method for a metal composite pipe with a corrugated joint surface. The invention can roll a complete spiral corrugation on the composite pipe blank by using the three-roller skew rolling mill, and integrates corrugation rolling and corrugation flattening processes on a set of rollers, thereby reducing the process flow and improving the production efficiency.)

1. A three-roller skew rolling forming method for a metal composite pipe with a corrugated joint surface is characterized in that a single-pass forming corrugation is arranged on the roller, the forming corrugation is distributed between the tail end of the biting section and the tail end of the forming section, the forming corrugations on the three rollers are distributed at staggered intervals, and the forming corrugations on the three rollers sequentially contact with the outer wall of the composite pipe blank, and the forming method comprises the following steps:

s1, inserting the mandrel into the composite tube blank, feeding the composite tube blank into a three-roller skew rolling mill for rolling, arranging three rollers around a rolling line at an angle of 120 degrees, rotating in the same direction, setting the deflection angle of the axis of each roller relative to the rolling line as a feed angle, setting the angle between the end surface of each roller and the rolling line as a rolling angle, and overlapping the central line of the mandrel with the rolling line;

s2, the pushing machine pushes the composite pipe blank along the rolling line direction at a certain speed, when the composite pipe blank is contacted with the biting section, the pushing machine stops pushing, and under the action of the friction force of the rollers, the composite pipe blank rotates around the rolling line and moves along the rolling line direction at the same time, so that the compound pipe blank is bitten;

s3, enabling the composite pipe blank to enter a forming section from the biting section, enabling forming corrugations on three rollers to be distributed at staggered intervals in space, enabling the composite pipe blank to be in contact with the forming corrugations on a first roller, enabling the composite pipe blank to rotate 1/3 circumference and axially feed for a certain feeding distance under the action of friction force, rolling primary spiral corrugations on the composite pipe blank, enabling the forming corrugations on a second roller to be in contact with the primary composite pipe blank corrugations, enabling the composite pipe blank to rotate 1/3 circumference again and axially feed for the same feeding distance, rolling secondary spiral corrugations on the basis of the primary spiral corrugations, enabling the forming corrugations on a third roller to be in contact with the secondary composite pipe blank, enabling the composite pipe blank to rotate 1/3 circumference again and axially feed for the same feeding distance, rolling tertiary spiral corrugations on the basis of the secondary corrugations, and enabling the tertiary corrugations to be formed gradually, rolling a complete spiral corrugation on the composite pipe blank;

and S4, continuously rotating and feeding the composite pipe blank, rolling and flattening the spiral corrugations on the upper outer wall of the composite pipe blank through a rolling and flattening section, and rolling on a combination interface of the composite pipe blank to form a corrugated combination surface.

2. The method of claim 1, further comprising a step S0 before the step S1: selecting a base pipe and a cladding pipe, and combining and blanking the base pipe and the cladding pipe in sequence to obtain a composite pipe blank.

3. The method of claim 2, further comprising a step S5 after the step S4: and (4) extracting the core rod from the composite pipe blank, and performing head-surrounding cutting, heat treatment, straightening and segmentation on the rolled composite pipe blank to obtain a final metal composite pipe finished product.

4. The three-roll skew rolling method for forming a metal composite tube with a corrugated bonding surface according to claim 1, 2 or 3, wherein the forming corrugations which are firstly contacted with the composite tube blank are positioned at the tail end of the biting section, and the forming corrugations which are contacted with the composite tube blank later are positioned at the forming section.

5. The method as claimed in claim 1, 2 or 3, wherein the forming corrugations are arranged perpendicular to the rolled flat section.

6. The method as claimed in claim 1, 2 or 3, wherein the three rolls have the same size of formed corrugation.

7. The three-roll skew rolling method for forming a metal composite tube having a corrugated bonding surface according to claim 1, 2 or 3, wherein the size of the formed corrugation which comes into contact with the composite tube blank after the three rolls is larger than the size of the formed corrugation which comes into contact with the composite tube blank before the three rolls.

Technical Field

The invention relates to the technical field of metal composite pipe forming, in particular to a three-roller skew rolling forming method for a metal composite pipe with a corrugated joint surface.

Background

The metal composite pipe is a metal composite pipe formed by combining an inner layer metal pipe (a base pipe and a cladding pipe) and an outer layer metal pipe (a cladding pipe) which are different, can fully utilize the best performance of the base pipe and the cladding pipe, and has quite wide application field due to the superior performance. In the prior art, the mainstream solid-solid phase composite process between a base pipe and a cladding pipe is a drawing composite method, a rolling composite method, a spinning composite method, a hot continuous rolling method, a hot extrusion method and the like, wherein a composite interface processed by cold deformation is usually in mechanical engagement, the bonding strength is low, and the composite interface can form stable metallurgical bonding under the action of high temperature, pressure and deformation in the processes of thermal deformation and special forming.

In recent research, the bonding strength of the metal composite pipe can be remarkably increased by rolling the corrugated surface of the metal composite pipe. The preparation of the metal composite pipe needs multiple frames, multiple holes and multiple passes, for example, a corrugated pipe blank is rolled on a rolling mill, and then a set of dies is replaced on another rolling mill to carry out corrugated rolling, so that the process flow and the production efficiency have improved space.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a three-roller skew rolling forming method for a metal composite pipe with a corrugated joint surface, which can roll a complete spiral corrugation on a composite pipe blank by using a three-roller skew rolling mill, integrates two processes of corrugation rolling and corrugation flattening on a set of rollers, reduces the process flow and improves the production efficiency.

In order to achieve the purpose, the invention provides the following technical scheme: a three-roller skew rolling forming method for a metal composite pipe with a corrugated joint surface is characterized in that the metal composite pipe is rolled on a three-roller skew rolling mill, three rollers are arranged on the three-roller skew rolling mill, a biting section, a forming section and a flattening section are sequentially arranged on the outer surface of each roller from the small head end of each roller to the large head end of each roller, single-pass forming corrugations are arranged on the rollers and distributed between the tail end of the biting section and the tail end of the forming section, the forming corrugations on the three rollers are distributed at staggered intervals, and the forming corrugations on the three rollers sequentially contact with the outer wall of a composite pipe blank, and the forming method comprises the following steps:

s1, inserting the mandrel into the composite tube blank, feeding the composite tube blank into a three-roller skew rolling mill for rolling, arranging three rollers around a rolling line at an angle of 120 degrees, rotating in the same direction, setting the deflection angle of the axis of each roller relative to the rolling line as a feed angle, setting the angle between the end surface of each roller and the rolling line as a rolling angle, and overlapping the central line of the mandrel with the rolling line;

s2, the pushing machine pushes the composite pipe blank along the rolling line direction at a certain speed, when the composite pipe blank is contacted with the biting section, the pushing machine stops pushing, and under the action of the friction force of the rollers, the composite pipe blank rotates around the rolling line and moves along the rolling line direction at the same time, so that the compound pipe blank is bitten;

s3, enabling the composite pipe blank to enter a forming section from the biting section, enabling forming corrugations on three rollers to be distributed at staggered intervals in space, enabling the composite pipe blank to be in contact with the forming corrugations on a first roller, enabling the composite pipe blank to rotate 1/3 circumference and axially feed for a certain feeding distance under the action of friction force, rolling primary spiral corrugations on the composite pipe blank, enabling the forming corrugations on a second roller to be in contact with the primary composite pipe blank corrugations, enabling the composite pipe blank to rotate 1/3 circumference again and axially feed for the same feeding distance, rolling secondary spiral corrugations on the basis of the primary spiral corrugations, enabling the forming corrugations on a third roller to be in contact with the secondary composite pipe blank, enabling the composite pipe blank to rotate 1/3 circumference again and axially feed for the same feeding distance, rolling tertiary spiral corrugations on the basis of the secondary corrugations, and enabling the tertiary corrugations to be formed gradually, rolling a complete spiral corrugation on the composite pipe blank;

and S4, continuously rotating and feeding the composite pipe blank, rolling and flattening the spiral corrugations on the upper outer wall of the composite pipe blank through a rolling and flattening section, and rolling on a combination interface of the composite pipe blank to form a corrugated combination surface.

By adopting the technical scheme, based on the technology of rolling the seamless steel tube by the three-roller skew rolling mill in the prior art, the rollers are improved and designed, forming corrugations are added on the rollers, the forming section can form the corrugations on the outer wall of the composite tube blank while reducing the wall and the diameter of the composite tube blank, the composite tube blank with the corrugations is rolled and leveled by the flattening section, a corrugated joint surface is rolled and leveled on the composite tube blank, the bonding strength of the metal composite tube is increased, the two processes of corrugation rolling and corrugation flattening are integrated on one set of rollers, the process flow is reduced, the production efficiency is improved, and meanwhile, because the forming corrugations on the three rollers are distributed at intervals, if the forming corrugations are synchronously distributed on the three rollers, the composite tube blank can be rolled to form three spiral corrugations when passing through the forming section, so that the surface of the composite tube blank is seriously deformed and rough in surface, The forming corrugations on the three rollers have a difference in distribution position, the composite pipe blank is axially fed along a rolling line while rotating, when the forming corrugations on the first roller contact the composite pipe blank, the forming corrugations on the second roller and the third roller do not contact the composite pipe blank, and when the forming corrugations on the second roller contact the composite pipe blank, the forming corrugations on the third roller do not contact the composite pipe blank, namely, the forming corrugations on the three rollers sequentially roll the same spiral corrugation on the composite pipe blank every 1/3 weeks, so that the same spiral corrugation is finally rolled by the three rollers, and the problem that the problem is caused by rolling multiple spiral corrugations is avoided.

The invention is further configured to: step S0 is further included before step S1: selecting a base pipe and a cladding pipe, and combining and blanking the base pipe and the cladding pipe in sequence to obtain a composite pipe blank.

The invention is further configured to: step S4 is also included after step S3: and (4) extracting the core rod from the composite pipe blank, and performing head-surrounding cutting, heat treatment, straightening and segmentation on the rolled composite pipe blank to obtain a final metal composite pipe finished product.

The invention is further configured to: the forming corrugation which is firstly contacted with the composite pipe blank is positioned at the tail end of the biting section, and the forming corrugation which is contacted with the composite pipe blank is positioned at the forming section. Through the arrangement, the composite pipe blank is in contact with the formed corrugation on the first roller in the biting process, and the formed corrugation is cut into simultaneously in the stable biting process of the biting section, so that the composite pipe blank is stabilized on the formed corrugation.

The invention is further configured to: the forming corrugations are arranged perpendicular to the rolled flat section. Through the arrangement, the formed corrugation is perpendicular to the rolling flat section when the outer wall of the composite pipe blank is rolled, the biting is more stable in the whole corrugation forming process, the resistance to the composite pipe blank can be reduced, the composite pipe blank can be smoothly fed, the composite pipe blank can be smoothly transited to the forming section, and the high-quality corrugation is formed on the outer wall of the composite pipe blank.

The invention is further configured to: the formed corrugations on the three rolls are the same size. With the arrangement, the formed corrugations with the same size can roll the corrugations with uniform depth on the wall of the composite pipe.

The invention is further configured to: in the three rolls, the size of the formed corrugation which comes into contact with the composite pipe blank later is larger than the size of the formed corrugation which comes into contact with the composite pipe blank first. Through the arrangement, the circular arc-shaped formed corrugation is taken as an example, the diameter of the formed corrugation which is contacted firstly is small, so that the corrugation is easy to bite, the quality of a bite section of the composite pipe blank can be improved, when the cladding pipe is thick, the corrugation extruded by the small-diameter corrugation is too shallow, an ideal corrugation combination interface is difficult to present after flattening, the circular arc-shaped formed corrugation with the small diameter is initially changed into the large-diameter formed corrugation immediately, so that the corrugation rolled on the surface of the composite pipe blank is not gradually changed and seriously deformed, and the formed corrugation quality is influenced.

The invention has the advantages that: 1) the composite pipe blank can form corrugations on the outer wall while reducing the wall and reducing the diameter, the corrugated composite pipe blank is rolled flat through a rolling flat section, a corrugated joint surface is rolled on the composite pipe blank, the bonding strength of the metal composite pipe is increased, two processes of corrugation rolling and corrugation rolling flat are integrated on one set of rollers, the process flow is reduced, and the production efficiency is improved; 2) the formed corrugations on the three rollers are distributed in staggered mode in sequence, the same spiral corrugation can be rolled by the three rollers, a series of consequences that the surface of the composite pipe blank is seriously deformed, the surface is rough, cracks are generated, the composite pipe blank is difficult to level and the like due to the fact that the three corrugations are rolled by the non-staggered corrugation are avoided, and the formed lead angle type corrugated joint surface can improve the stripping resistance and the torsional strength of the composite pipe blank.

Drawings

FIG. 1 is a schematic view of a three-roll rolling process according to the present invention;

FIG. 2 is a schematic view of the structure of the roll of the present invention;

FIG. 3 is a schematic view of the present invention with three rolls juxtaposed;

fig. 4 is a development view of the composite shell in the present invention.

Reference numerals: the forming device comprises a first roller 100, a second roller 101, a third roller 102, a biting section 103, a forming section 104, a flattening section 105, forming corrugations 106, a composite pipe blank 200, a base pipe 201, a cladding pipe 202, a core rod 203, a primary spiral corrugation 301, a secondary spiral corrugation 302 and a tertiary spiral corrugation 303.

Detailed Description

In the description of the present embodiment, it should be noted that, as the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "rear", etc. appear, their indicated orientations or positional relationships are based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" as appearing herein are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The invention is further described with reference to the drawings and the specific embodiments in the following description.

Example (b): as shown in figures 1 to 4 of the drawings,

a metal composite tube with a corrugated joint surface is rolled on a three-roll skew rolling mill, three rolls are arranged on the three-roll skew rolling mill, an engaging section 103, a forming section 104 and a flattening section 105 are sequentially arranged on the outer surfaces of the rolls from the small head ends of the rolls to the large head ends of the rolls, a single-pass forming corrugation 106 is arranged on the rolls, the forming corrugation can be in the shape of an arc, a rectangle, a sine wave and the like, the forming corrugations are distributed between the tail end of the engaging section and the tail end of the forming section, the forming corrugations on the three rolls are distributed at staggered intervals, the forming corrugations on the three rolls sequentially contact with the outer wall of a composite tube blank 200, and for convenience, the three rolls are respectively a first roll 100, a second roll 101 and a third roll 102 according to the sequential order of the forming corrugations contacting with the composite tube blank. The forming corrugation which is firstly contacted with the composite pipe blank is positioned at the tail end of the biting section, the forming corrugation which is contacted with the composite pipe blank is positioned at the forming section, the composite pipe blank is contacted with the forming corrugation on the first roller in the biting process, and the forming corrugation is cut in simultaneously in the stable biting process of the biting section, so that the composite pipe blank is stabilized on the forming corrugation. The forming corrugations are arranged perpendicular to the rolling flat section, the forming corrugations are perpendicular to the rolling flat section when the outer wall of the composite pipe blank is rolled, the biting is more stable in the whole corrugation forming process, the resistance to the composite pipe blank can be reduced, the composite pipe blank can be smoothly fed, the composite pipe blank can be smoothly transited to the forming section, high-quality corrugations are formed on the outer wall of the composite pipe blank, the peaks and the troughs of spiral corrugations formed on the composite pipe blank can be consistent, gradient type corrugations are not formed, when the rolling flat section is rolled flat, the composite pipe blank is stressed consistently, the problem that bulging is caused at the joint of a base pipe and a cover pipe due to inconsistent rolling force is avoided, the surface quality of the composite pipe blank is guaranteed, and the combination quality of the composite pipe blank is improved.

The formed corrugations on the three rolls can be the same size, and the formed corrugations with the same size can roll the corrugations with the same uniform depth on the composite pipe wall. In addition, the sizes of the formed corrugations on the three rollers can be designed to be different as in the embodiment, in the three rollers, the size of the formed corrugation which is contacted with the composite pipe blank at the back is larger than the size of the formed corrugation which is contacted with the composite pipe blank at the first (the height and the width of the formed corrugation), taking the formed corrugation which is in the shape of a circular arc as an example, the diameter of the formed corrugation which is contacted at the first is small so that the corrugation can be bitten, the quality of a biting section of the composite pipe blank can be improved, but when the covering pipe is thicker, the corrugation which is pressed out by the corrugation with a small diameter is too shallow, an ideal corrugation combination interface is difficult to present after the covering pipe is flattened, and the formed corrugation which is formed by starting from the circular arc formed corrugation with a small diameter and then immediately changing into the formed corrugation with a large diameter can lead the corrugation rolled on the surface of the composite pipe blank, the sizes of the formed corrugations on the first roller, the second roller and the third roller are different, so that the rolled small corrugations can be smoothly transited to large corrugations, and then the small corrugations are rolled flat, and the forming quality is improved.

The forming method specifically comprises the following steps:

firstly, selecting a base pipe 201 and a cover pipe 202, combining and manufacturing a blank according to the sequence that the base pipe is arranged inside and outside the cover pipe, wherein the deformation resistance of the base pipe is smaller than that of the cover pipe, so that the deformation can go deep into the base pipe from outside to inside, and then sending the combined blank into a press machine to be pressed tightly to obtain a composite pipe blank;

secondly, a mandrel 203 is inserted into the composite pipe blank, the central line of the mandrel is positioned on the same straight line with the composite pipe blank and a rolling line, the inner surface of the composite pipe blank is contacted with the mandrel, the mandrel is a smooth round mandrel, the composite pipe blank is deformed towards the base pipe from a covering pipe in the rolling process, so that the formed metal composite pipe can be demoulded by using the existing demoulding equipment, the composite pipe blank with the mandrel is fed into a three-roll skew rolling mill for rolling, three rollers are mutually arranged at 120 degrees around the rolling line and rotate in the same direction, the deflection angle of the axis of each roller relative to the rolling line is a feeding angle, the value is a floating value, the adjustment is carried out according to the size of the composite pipe blank to be rolled, the feeding angle can realize the rotation and the axial feeding of the composite pipe blank, and the feeding angle directly influences the roundness of the composite; the angle between the end face of each roller and the rolling line is a rolling angle, and the central line of the mandrel is superposed with the rolling line;

thirdly, the pushing machine pushes the composite pipe blank along the rolling line direction at a certain speed, when the composite pipe blank is contacted with the biting section, the pushing machine stops pushing, and under the action of the friction force of the rollers, the composite pipe blank rotates around the rolling line and moves along the rolling line direction at the same time, so that the compound pipe blank is bitten;

fourthly, the composite pipe blank enters a forming section from the biting section, forming corrugations on three rollers are distributed at intervals in a staggered manner, the composite pipe blank is in contact with the forming corrugations on a first roller, under the action of friction force, the composite pipe blank rotates 1/3 in the circumferential direction and axially feeds for a certain feeding distance, primary spiral corrugations 301 are rolled on the composite pipe blank, at the moment, the forming corrugations on a second roller are in contact with the primary composite pipe blank corrugations, the composite pipe blank rotates 1/3 in the circumferential direction again and axially feeds for the same feeding distance, two-pass spiral corrugations 302 are rolled on the basis of the primary spiral corrugations, then the forming corrugations on a third roller are in contact with the two-pass composite pipe blank, the composite pipe blank rotates 1/3 in the circumferential direction again and axially feeds for the same feeding distance, three-pass spiral corrugations 303 are rolled on the basis of the two-pass corrugations, the three secondary corrugations are formed gradually, and a complete spiral corrugation is rolled on the composite pipe blank;

for single wave offset rolling, the waves on the three rollers are arranged in an offset manner, so that the waves extruded by different rollers can be combined, and the three rollers jointly extrude a gradual spiral wave in the whole rolling process.

During skew rolling, metal generates tangential and axial slip relative to the surface of the roller, the tangential slip is relatively small according to practical experience, and the tangential slip coefficient can be approximately taken as eta_t≈1；

The composite pipe blank mainly generates axial sliding, wherein the axial sliding coefficient of the composite pipe blank during rolling can be calculated according to an empirical formula,

wherein eta is_ixThe axial slip coefficient of the ith section;

mu is a friction coefficient;

alpha is a feed angle;

d_ri,d_cithe diameters of the tube blanks at the inlet and the outlet of the ith section;

d_pis the diameter of the core rod;

M_ciis the area of the corrugation at the exit of the i-th section.

In the skew rolling process, the composite pipe blank not only rotates around the axis of the composite pipe blank, but also feeds forwards along the rolling line, after the axial and tangential slip coefficients are obtained, the feeding distance s of the composite pipe blank can be calculated when the composite pipe blank rotates 1/3 circles, namely when a certain point on the composite pipe blank, which is in contact with a previous roller, rotates to the contact position with a next roller, and the distance can be calculated according to an empirical formula as follows:

wherein the content of the first and second substances,

is the cross-sectional area of the outlet of the i-th section;

is the cross-sectional area of the inlet of the i-th section;

M_rithe area of the corrugation at the inlet of the ith section;

therefore, for single-wave offset skew rolling, the space between the first roller and the second roller for forming the corrugations is s 1; the spacing between the second and third rolls to form the corrugations should be s 2.

And fifthly, continuously feeding the composite pipe blank in a rotating manner, flattening the spiral corrugations on the upper outer wall of the composite pipe blank through a flattening section, and rolling on a bonding interface of the composite pipe blank to form a corrugated bonding surface.

And sixthly, drawing out the core rod from the composite pipe blank, cutting the rolled composite pipe blank to form a head circumference, performing heat treatment, straightening and segmenting to obtain a final metal composite pipe finished product.

By adopting the technical scheme, based on the technology of rolling a seamless steel pipe by a three-roller skew rolling mill in the prior art, the roller is improved and designed, forming corrugations are added on the roller, the forming section can form spiral corrugations on the outer wall of a composite pipe blank while reducing the wall and the diameter of the composite pipe blank, the single transverse corrugation joint surface can greatly improve the anti-stripping strength of the metal composite pipe but cannot improve the anti-torsion strength between a base pipe and a cladding pipe, the single longitudinal corrugation joint surface can greatly improve the anti-torsion strength of the metal composite pipe but cannot improve the anti-stripping strength between the base pipe and the cladding pipe, the spiral corrugations combine the advantages of the transverse corrugations and the longitudinal corrugations, the composite pipe blank rolled with the spiral corrugations is rolled to be flat by a rolling section, the corrugated joint surface is rolled on the composite pipe blank, the combination strength of the metal composite pipe is increased, two processes of corrugation rolling and corrugation rolling are integrated on one set of roller, the integration of three times of rough rolling and the integration of rough rolling and finish rolling reduce the process flow to a great extent, improve the production efficiency, save the processing time and cost, have low energy consumption and can be produced in a large scale. Meanwhile, because the forming corrugations on the three rollers are distributed at staggered intervals, if the forming corrugations are synchronously distributed on the three rollers, the composite pipe blank can roll three helical corrugations when passing through a forming section, the forming corrugations of the invention have a difference value at the distribution positions of the three rollers, the composite pipe blank rotates and simultaneously axially feeds along a rolling line, when the forming corrugations on the first roller contact the composite pipe blank, the forming corrugations on the second roller and the third roller do not contact the composite pipe blank, and when the forming corrugations on the second roller contact the composite pipe blank, the forming corrugations on the third roller do not contact the composite pipe blank, namely, the forming corrugations on the three rollers roll the same helical corrugations on the composite pipe blank in sequence every 1/3 weeks, so that the same helical corrugation is ensured to be finally rolled by the three rollers, and the phenomenon that the helical corrugations of the composite pipe blank with multiple rolling paths have serious deformation on the surface of the composite pipe blank is avoided, Rough surface, crack generation, difficult rolling and the like.

The above embodiments are described in detail for the purpose of further illustrating the present invention and should not be construed as limiting the scope of the present invention, and the skilled engineer can make insubstantial modifications and variations of the present invention based on the above disclosure.