CN115069801A - Multi-pass drawing forming process for cladding tube with straight ribs and cladding tube - Google Patents

Abstract

The invention relates to the technical field of metal plastic forming process and equipment, and provides a multi-pass drawing forming process of a cladding tube with a straight rib. Bright annealing is used between different forming stages to eliminate residual stress, improve work hardening and further restore its plasticity. The invention reduces the problems of limited filling height of the rib in single-pass drawing forming and defects caused by the inner surface depression of the corresponding position of the rib in the rib groove filling process, the section of the tube is gradually transited among the passes after the process is adopted for forming, the ribbed tube with the wall thickness larger than that of the finished tube can be formed, and the formed tube has high section precision, small error and higher strength and rigidity.

Description

A kind of multi-pass drawing forming process of cladding tube with straight ribs and cladding tube

technical field

The invention relates to the technical field of metal plastic forming technology and equipment, in particular to a multi-pass drawing forming process and a cladding tube of a cladding tube with straight ribs.

Background technique

The cladding tube is an important structural part of the core, and its main function is to protect the fuel pellets from the corrosion of the coolant and avoid the leakage of fissile substances in the cladding. The ribbed tube is a new type of nuclear fuel cladding tube currently used because its outer surface has ribs protruding from the tube, which can enhance the heat transfer performance of the coolant and promote fluid mixing. Due to the small size of the outer surface rib, the traditional production process of the ribbed pipe is to wrap the iron wire on the outer surface of the thin-walled pipe and fix it by electric welding. However, this method cannot achieve integrated molding, has low production efficiency and poor surface size, which leads to the isolation failure of the cladding tube due to rib separation during subsequent high-temperature and high-pressure service. In order to improve this situation and improve the safe service performance of the cladding tube, it is urgent to carry out the integrated molding of the ribbed tube. At the same time, since the height of the ribs on the outer surface of the ribbed pipe is greater than or equal to the wall thickness of the finished pipe, problems such as insufficient rib filling height and rib groove defects on the inner surface of the corresponding position due to rib filling on the outer surface of the pipe will occur during the forming process. Therefore, how to ensure the height of the ribs on the outer surface of the pipe and eliminate the defects of the rib grooves on the inner surface at the same time during the integrated forming process is a technical problem.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a multi-pass drawing forming process and a cladding tube of a cladding tube with straight ribs. , it is easy to produce defects and can not meet the requirements of defects. The pipe formed by this process has high cross-section accuracy, small error, high strength and rigidity, and ensures the safe service requirements of nuclear fuel cladding pipes.

The present invention adopts following technical scheme:

In one aspect, the present invention provides a multi-pass drawing forming process for a cladding tube with straight ribs, comprising: using a circular section tube as an initial tube blank, and the initial tube blank is under the joint action of a mold and a mandrel, After successively passing through the pre-forming stage corresponding to the first special-shaped mold, the transition forming stage corresponding to the second special-shaped mold, and the finished product forming stage corresponding to the third special-shaped mold, it is finally formed into a finished product with a straight rib cladding tube with a certain characteristic cross-section. Pipe material; the mandrel is used to control the inner diameter size of the special-shaped section pipe after the corresponding pass forming, and the first special-shaped mold, the second special-shaped mold, and the third special-shaped mold are respectively used to control the corresponding pass. Outer diameter size and straight rib size.

Any of the above-mentioned possible implementations further provides an implementation, in which bright annealing is used between each forming stage of the pre-forming stage, the transition forming stage, and the final forming stage to eliminate residual stress, improve work hardening and further restore its plasticity.

Any of the above-mentioned possible implementations further provides an implementation, wherein the number of the first special-shaped mold and the third special-shaped mold is one, and the number of the second special-shaped mold is one or several;

The first special-shaped mold, the second special-shaped mold, and the third special-shaped mold all include a conical inlet section and a cylindrical sizing section that are connected in sequence;

The taper of the inlet section is α, and the inlet section is provided with one or several inclined grooves with a taper of β; α=5～15°, β=2～10°; α and β are too small or too large. Causes poor rib filling and tube fracture during drawing;

One or several special-shaped grooves with a certain width, height and filling angle are arranged on the inner wall of the sizing section, the bottom of the special-shaped groove is rounded, and the fillet radius is R;

Any of the above-mentioned possible implementations further provides an implementation. In the pre-forming stage, the sizing section of the first special-shaped mold has a width of W1, a height of H1, a fillet radius of R1 and a filling angle ω1. For the special-shaped groove, the selection range of process parameters is: W1=(1～1.5)W3, H1=(0.2～0.5)H3, R1=(1～20)R3, ω1=90～150°; W3, H3, R3, ω3 are the mold parameters of the third special-shaped mold (finished product forming stage): the width, height, fillet radius and filling angle of the special-shaped groove in the sizing section, which are determined by the finished pipe and are the same size as the finished pipe.

Any of the above-mentioned possible implementations further provides an implementation. In the transition forming stage, the sizing section of the second special-shaped mold has a width of W2, a height of H2, a fillet radius of R2 and a filling angle ω2. For the special-shaped groove, the selection range of process parameters is: W2=(1.5～2)W3, H2=(0.7～0.8)H3, R2=(1～5)R3, ω2=90～130°; W3, H3, R3, ω3 are the mold parameters of the third special-shaped mold (finished product forming stage): the width, height, fillet radius and filling angle of the special-shaped groove in the sizing section.

Any of the above-mentioned possible implementation manners further provides an implementation manner. The selection range of process parameters between adjacent passes of drawing is: the diameter reduction rate is 10% to 35%, and the wall thickness reduction rate is 10%. %～25%. A reduction rate below the minimum value of the selected range cannot meet the rib filling requirements, while a reduction rate above the maximum value of the selected range will result in excessive deformation and breakage.

According to any of the possible implementations described above, an implementation is further provided, wherein the height of the straight ribs of the finished pipe is greater than or equal to the wall thickness of the finished pipe.

Any of the above-mentioned possible implementations further provides an implementation, when several second special-shaped molds are used, the diameter of the pipe, the wall thickness of the pipe, the width of the straight rib, the height of the straight rib, the straight The deformation of the filling angle of the ribs is jointly realized by several second special-shaped molds.

Any of the above-mentioned possible implementations further provides an implementation, wherein the mandrel in different forming stages is defined by a conical inlet section with a taper γ and a cylindrical shape with an outer diameter of Φ ₂ and a length of L ₂ . Diameter composition. The selection range of process parameters is: L ₂ =0.1-1mm, γ=10-30°; the range of the length L ₁ of the sizing section of the first special-shaped mold, the second special-shaped mold, and the third special-shaped mold is: L ₁ ＝0.5～5mm, if L ₁ is too small, the pipe will spring back and the outer diameter of the pipe will be larger than the target value after deformation. If L ₁ is too large, the drawing force will be too large and the pipe will be broken; if L ₂ is too small, the deformation cannot be guaranteed. _The dimensional accuracy of the inner surface of the rear pipe, if L2 is too large, the drawing force will be too large and the pipe will be broken.

Any of the above-mentioned possible implementations further provides an implementation. Different forming stages are used in conjunction with a special-shaped mold and a mandrel, and the special-shaped mold sizing section L ₁ is greater than or equal to the mandrel sizing section L ₂ during use. The die sizing section should include the mandrel sizing section.

According to any of the possible implementations described above, an implementation is further provided, wherein the material of the straight rib cladding tube is stainless steel or zirconium alloy tube for nuclear fuel.

Any of the above-mentioned possible implementations further provides an implementation, and the specific steps of each drawing are as follows:

①Fix the special-shaped mold on the frame; ②Adjust the position of the mandrel sizing section and the special-shaped mold sizing section by adjusting the nut at the end of the mandrel, so that the mold sizing section includes the sizing section of the mandrel; One end of the pipe is reduced by the shrinking machine, so that the outer diameter of the pipe blank is smaller than the size of the inner hole of the special-shaped mold; ④ Evenly apply the drawing lubricating oil on the inner and outer surfaces of the pipe; ⑤ Pass the pipe at the shrinking end through the mold; Insert the adjusted mandrel; ⑦ Apply a pulling force to the pipe passing through the mold, and the mandrel inserted into the pipe also moves in the direction of the applied force. After the mandrel moves to the previously adjusted position, it will not change again; 8. The tube blank is plastically deformed under the combined action of the special-shaped mold and the mandrel.

When matching between different passes, in order to increase the filling degree of the rib and prevent the inner surface of the corresponding position of the rib from flowing into the mold groove due to the transition of the metal, and thus causing groove defects on the inner surface, the deformation degree of different passes in the process design is different. The value of each parameter is lower than the minimum value of the selected range, which is not conducive to the next rib filling, and the rib groove defect will occur if the value of each parameter is higher than the maximum value of the selected range, which will affect the dimensional accuracy of the finished pipe.

On the other hand, the present invention also provides a cladding tube with straight ribs, which is obtained by the above-mentioned multi-pass drawing and forming process of the cladding tube with straight ribs, and the rib height of the cladding tube with straight ribs is greater than or equal to Wall thickness of cladding tubes with straight ribs.

The beneficial effects of the present invention are:

The invention reduces the problems that the rib filling height is limited in the single-pass drawing forming process and the defects on the inner surface of the rib corresponding position during the filling process of the rib groove are reduced. The ribbed pipe is larger than the wall thickness of the finished pipe, and the section of the pipe after forming has high precision, small error, and high strength and rigidity.

Description of drawings

FIG. 1 is a schematic diagram showing a drawing and forming process of a cladding tube with straight ribs according to an embodiment of the present invention.

FIG. 2 is a schematic view of the structure of the cladding tube with straight ribs in the embodiment.

FIG. 3 is a cross-sectional view of the pipe after forming in different passes during the multi-pass drawing process of the cladding tube with straight ribs in the embodiment.

FIG. 4 is a partial enlarged view of the cross-section of the pipe material after the multi-pass drawing process of the cladding tube with straight ribs in the embodiment after forming in different passes.

FIG. 5 is a schematic diagram showing the structure of the special-shaped mold in the drawing and forming process of the cladding tube with straight ribs in the embodiment.

FIG. 6 is a schematic diagram showing the structure of the mandrel in the drawing and forming process of the cladding tube with straight ribs in the embodiment.

Detailed ways

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects. In the drawings of the following embodiments, the same reference numerals appearing in the various drawings represent the same features or components, which may be used in different embodiments.

According to an embodiment of the present invention, a multi-pass drawing forming process for a cladding tube with straight ribs includes: using a circular section tube as an initial tube blank, and the initial tube blank is sequentially passed through the first tube under the joint action of the mold and the mandrel. The pre-forming stage corresponding to a special-shaped mold, the transition forming stage corresponding to the second special-shaped mold, and the finished product forming stage corresponding to the third special-shaped mold are finally formed into a finished pipe with a straight rib cladding tube with a certain characteristic cross-section; The mandrel is used to control the inner diameter size of the special-shaped section pipe after the corresponding pass forming, and the first special-shaped mold, the second special-shaped mold, and the third special-shaped mold are respectively used to control the outer diameter size of the special-shaped section pipe after the corresponding pass forming. and straight rib size.

In a specific embodiment, bright annealing is used between the preforming stage, the transition forming stage and the final product forming stage to eliminate residual stress, improve work hardening and further restore its plasticity.

In a specific embodiment, the number of the first special-shaped mold and the third special-shaped mold is one, and the number of the second special-shaped mold is one or several. When several second special-shaped dies are used, the deformation of pipe diameter, pipe wall thickness, straight rib width, straight rib height, and straight rib filling angle in the transitional forming stage are jointly realized by several second special-shaped dies.

As shown in Figure 1, the drawing steps of any one pass are as follows: ① Fix the mold on the frame; ② Adjust the nut at the end of the mandrel so that the sizing section of the mandrel and the sizing section of the mold coincide; ③ Put the pipe One end is reduced by the shrinking machine, so that the outer diameter of the tube blank is smaller than the size of the inner hole of the mold; ④ The inner and outer surfaces of the pipe are evenly coated with drawing lubricating oil to remove the pipe; ⑤ The pipe at the shrinking end is passed through the mold; Insert the mandrel in the adjusted position; ⑦ Apply a pulling force to the pipe passing through the mold, and the mandrel inserted into the pipe also moves in the direction of the applied force. After the mandrel moves to the previously adjusted position, it will not change again; 8. The tube blank is plastically deformed under the combined action of the mold and the mandrel.

The cladding tube with straight ribs prepared by the present invention is shown in Figure 2, the tube has one or more ribs protruding from the outer surface, the ribs are straight and the rib height is greater than or equal to the wall thickness of the tube, which is a typical difficult integration Shaped different-wall shaped tubes.

As shown in Figure 3, in a specific embodiment, the cross-sectional view of the pipe material after different passes of the drawing process of the cladding pipe with straight ribs in multiple passes, the circular cross-section pipe material is used as the initial blank, and passes through the first special-shaped mold, The second special-shaped mold and the third special-shaped mold draw the circular section tube blank into a special-shaped tube with a certain characteristic section under the combined action of the mandrel and the special-shaped mold, and the corresponding forming stages are respectively called the first stage pre-forming stage, the second stage transition forming stage and the third stage finished product forming stage. The drawing process of each pass is a forming process in which the diameter and wall thickness of the pipe are reduced. Except that the outer diameter and wall thickness of the final product are determined by the target size, the selection range of process parameters between the other passes is: the diameter reduction rate is 10%. ～35%, the wall thickness reduction rate is 10%～25%. A reduction rate below the minimum value of the selected range cannot meet the rib filling requirements, while a reduction rate above the maximum value of the selected range will result in excessive deformation and breakage.

As shown in FIG. 4 , in a specific embodiment, a partial enlarged view of the cross-section of the pipe after forming in different passes in the multi-pass drawing process of the cladding tube with straight ribs. The pre-shaped sizing section has a special-shaped groove with a width W1, a height H1, a fillet radius R1 and a filling angle ω1. The selection range of process parameters is: W1=(1～1.5)W3, H1=(0.2～0.5)H3, R1=(1～20)R3, ω1=90～150°. The transition forming sizing section has a special-shaped groove with a width of W2, a height of H2, a fillet radius of R2 and a filling angle of ω2. The selection range of process parameters is: W2=(1.5～2)W3, H2=(0.7～0.8)H3, R2=(1～5)R3, ω2=90～130°. In the final drawing stage (finished product forming stage), the third special-shaped mold parameters (inner hole diameter Φ ₁ , width W3, height H3, fillet radius R3 and filling angle ω3) and mandrel parameters (outer diameter Φ ₂ ) are determined by the size of the finished pipe decision, the same size as the target product. When matching between different passes, in order to increase the filling degree of the rib and prevent the inner surface of the corresponding position of the rib from flowing into the mold groove due to the metal transition, and then groove defects on the inner surface, the deformation degree of the other different passes in the process design is different. . The value of each parameter is lower than the minimum value of the selected range, which is not conducive to the next rib filling, and the rib groove defect will occur if the value of each parameter is higher than the maximum value of the selected range, which will affect the dimensional accuracy of the finished pipe.

As shown in FIG. 5 , in a specific embodiment, a schematic diagram of the structure of a special-shaped mold. The special-shaped molds at different forming stages are used to control the outer diameter and rib size of the special-shaped section pipe after forming, and are composed of a conical inlet section and a cylindrical sizing section. Wherein, the taper of the inlet section is α, and the inlet section has a plurality of inclined grooves with a taper of β. The selection range of process parameters is: α=5～15°, β=2～10°, if α and β are too small or too large, it will lead to poor rib filling effect and pipe fracture during drawing. The inlet section has a plurality of special-shaped cross-section chutes, which are width W, height H, fillet radius R and filling angle ω. The selection range of the length of the sizing section as L ₁ is: L ₁ =0.5～5mm. If L1 is too small, the pipe will spring back and the outer diameter _of the pipe will be larger _than the target value after deformation. If L1 is too large, the drawing force will be too large and the pipe will be broken.

As shown in FIG. 6, in a specific embodiment, a schematic diagram of the structure of the mandrel. The mandrels in different forming stages are used to control the inner diameter size of the special-shaped section pipe after forming, which consists of a conical inlet section with a taper γ and a cylindrical sizing section with an outer diameter of Φ ₂ and a length of L ₂ . The selection range of process parameters is: L ₂ =0.1～1mm, γ=10～30°. If L2 is too small, the dimensional accuracy of the inner surface of the pipe cannot be guaranteed. If _L2 is too large, the drawing force will be too large and the pipe will be broken. _The lubricating effect of λ within this parameter range is better, and the drawing force can be reduced. Different forming stages are used in conjunction with the special-shaped mold and the mandrel. When using, the special _- shaped mold sizing section L1 is greater _than or equal to the mandrel sizing section L2, and the mold sizing section should include the mandrel sizing section.

The pipe material in the following comparative example is 316L stainless steel.

Comparative Example 1

When the diameter of the target product tube is 6mm and the wall thickness is 0.5mm, the size and performance of the product obtained by single pass and multi-pass (3 passes) are compared. The maximum rib height that can be obtained during single-pass drawing is 0.284 mm, which is only 56.8% filled compared to the wall thickness. The maximum rib height that can be obtained after the multi-pass drawing proposed in this paper is 0.496mm, which is 99.2% compared to the wall thickness filling. Therefore, the rib height is increased by 42.4%, and the rib filling effect is obviously improved compared with the product obtained by the single-pass drawing scheme using the multi-pass drawing scheme proposed in this paper. In addition, the increase in the height of the ribs on the outer surface increases the tensile strength of the ribbed tube by 6-12%.

Comparative Example 2

When the diameter of the target product tube is 6mm and the wall thickness is 0.5mm, the product size and performance obtained by comparing the ordinary and the multi-pass scheme proposed in this paper (both are 3 passes). The common multi-pass drawing scheme is adopted, that is, the rib groove width W and the rib groove height H are set to be the same in each pass (W1=W2=W3, H1=H2=H3), and the maximum rib height that can be obtained is 0.418 mm, only 83.6% of the wall thickness is filled, and a defect with a depth of 0.298mm appears on the inner surface of the pipe corresponding to the rib, which accounts for more than half of the wall thickness compared to 59.6% of the wall thickness. When using the multi-pass drawing scheme proposed in this paper, that is, setting different rib groove widths W and rib groove heights H (W1=1.5W3, W2=1.3W3, H1=0.4H3, H2=0.8H3), the ribs can be obtained. The maximum height is 0.496mm, which is 99.2% filled compared to the wall thickness, and the depth of the defect is 0.076mm, which is 15.2% compared to the wall thickness. To sum up, the multi-pass drawing scheme proposed in this paper improves the rib height by 15.6% and the defect depth by 44.4% compared with the traditional scheme. The rib filling effect is significantly improved, and the rib groove defect is further eliminated. In addition, the increase of the rib height on the outer surface increases the tensile strength of the ribbed tube by 6-8%, and the reduction of the rib groove on the inner surface greatly improves the stability and strength of the combination of the rib and the tube, increasing the extreme environment of the cladding tube in nuclear fuel. below the service life.

Comparative Example 3

When the diameter of the target product pipe is 6 mm and the wall thickness is 0.5 mm, the product size and performance obtained by comparing the ordinary and the multi-pass scheme proposed in this paper (both are 4 passes, the present invention corresponds to two second special-shaped molds). A common multi-pass drawing scheme is adopted, that is, the rib groove width W and the rib groove height H are set to be the same in each pass (W1=W21=W22=W3, H1=H21=H22=H3). At this time, the maximum rib height that can be obtained is 0.478mm, which is 95.6% filled compared to the wall thickness, and a defect with a depth of 0.364mm appears on the inner surface of the pipe corresponding to the rib, compared to the wall thickness. 72.8%, accounting for more than half of the wall thickness. When the multi-pass drawing scheme proposed in this paper is adopted, that is, different rib groove widths W and rib groove heights H are set (W1=1.6W3, W21=1.4W3, W22=1.2W3, H1=0.35H3, H21=0.7H3, H22=0.85H3), where W21 and W22 are the widths of the special-shaped grooves in the sizing section of the two second special-shaped molds respectively, H21 and H22 are the heights of the special-shaped grooves in the sizing sections of the two second special-shaped molds, respectively, and the height of the ribs can be obtained. The maximum value is 0.734mm, which is 146.8% compared to the wall thickness, and the depth of the defect is 0.136mm, which is 27.2% compared to the wall thickness. To sum up, the multi-pass drawing scheme proposed in this paper improves the rib height by 51.2% and the defect depth by 45.6% compared with the traditional scheme, and obtains the pipe with the rib filling height greater than the wall thickness and the rib groove defect. also further eliminated. The increase in the height of the outer surface rib increases the tensile strength of the ribbed pipe by 7-9%, which greatly increases the height of the outer surface rib of the ribbed pipe. In addition, tubing with a rib height greater than wall thickness can further improve the positioning spacing of ribbed cladding tubes from each other in nuclear fuel applications. By extending the scheme of this paper to different passes, a variety of ribbed tubes with different rib heights can be manufactured, and a variety of products with different rib heights in nuclear fuel cladding tubes can be realized.

It should be noted that the preformed shapes, transitional forming shapes and finished forming shapes selected in the above examples, and even the number of drawing passes, are only one of multiple choices. It can be extended to other types of multi-pass forming processes for cladding tubes.

The invention reduces the problems that the rib filling height is limited in the single-pass drawing forming process and the defects on the inner surface of the rib corresponding position during the filling process of the rib groove are reduced. The ribbed pipe is larger than the wall thickness of the finished pipe, and the section of the pipe after forming has high precision, small error, and high strength and rigidity.

Although several embodiments of the present invention have been presented herein, those skilled in the art should understand that changes may be made to the embodiments herein without departing from the spirit of the present invention. The above-mentioned embodiments are only exemplary, and the embodiments herein should not be construed as limiting the scope of the rights of the present invention.

Claims (10)

1. A multi-pass drawing and forming process for a cladding tube with straight ribs, wherein the forming process comprises: using the prepared circular section pipe material as an initial tube blank, the initial tube blank is placed in a mold and a mold. Under the combined action of the mandrel, it sequentially passes through the pre-forming stage corresponding to the first special-shaped mold, the transition forming stage corresponding to the second special-shaped mold, and the finished product forming stage corresponding to the third special-shaped mold, and finally formed into a certain characteristic cross-section. The finished pipe with straight rib cladding tube; the mandrel is used to control the inner diameter of the special-shaped section pipe after the corresponding pass is formed, and the first special-shaped mold, the second special-shaped mold, and the third special-shaped mold are respectively used to control the corresponding channel. The outer diameter size and straight rib size of the special-shaped section pipe after primary forming. 2. The multi-pass drawing forming process of the cladding tube with straight ribs as claimed in claim 1, characterized in that, bright annealing is adopted between each forming stage of the pre-forming stage, the transition forming stage and the finished product forming stage to eliminate the Residual stress, restore plasticity. 3. The multi-pass drawing forming process of the cladding tube with straight ribs according to claim 1, wherein the number of the first special-shaped mold and the third special-shaped mold is one, and the second special-shaped mold The number is one or several; The first special-shaped mold, the second special-shaped mold, and the third special-shaped mold all include a conical inlet section and a cylindrical sizing section that are connected in sequence; The taper of the inlet section is α, and one or several inclined grooves with a taper of β are arranged on the inlet section; α=5～15°, β=2～10°; One or several special-shaped grooves with a certain width, height and filling angle are arranged on the inner wall of the sizing section, and the bottom of the special-shaped groove is rounded with a radius of R. 4. The multi-pass drawing forming process of the cladding tube with straight ribs as claimed in claim 3, wherein in the pre-forming stage, the sizing section of the first special-shaped mold has a width of W1, a height of H1, For special-shaped grooves with fillet radius R1 and filling angle ω1, the selection range of process parameters is: W1=(1～1.5)W3, H1=(0.2～0.5)H3, R1=(1～20)R3, ω1=90～ 150°; W3, H3, R3, ω3 are the width, height, fillet radius and filling angle of the special-shaped groove of the sizing section of the third special-shaped mold respectively. 5. The multi-pass drawing forming process of the cladding tube with straight ribs as claimed in claim 3, wherein in the transition forming stage, the sizing section of the second special-shaped mold has a width of W2, a height of H2, For special-shaped grooves with fillet radius R2 and filling angle ω2, the selection range of process parameters is: W2=(1.5～2)W3, H2=(0.7～0.8)H3, R2=(1～5)R3, ω2=90～ 130°; W3, H3, R3, ω3 are the width, height, fillet radius and filling angle of the special-shaped groove of the sizing section of the third special-shaped mold respectively. 6. The multi-pass drawing forming process for a cladding tube with straight ribs as claimed in any one of claims 1-5, wherein the selection range of process parameters between adjacent drawing passes is: diameter reduction rate It is 10% to 35%, and the wall thickness reduction rate is 10% to 25%. 7 . The multi-pass drawing forming process of the cladding tube with straight ribs according to claim 1 , wherein the height of the straight ribs of the finished pipe is greater than or equal to the wall thickness of the finished pipe. 8 . 8. The multi-pass drawing forming process of the cladding tube with straight ribs as claimed in claim 3, wherein when several second special-shaped dies are used, the diameter of the pipe, the wall thickness of the pipe, the straight rib in the transition forming stage The deformation of the width of the straight rib, the height of the straight rib, and the filling angle of the straight rib are jointly realized by several second special-shaped molds. 9 . The multi-pass drawing forming process of the cladding tube with straight ribs according to claim 1 , wherein the mandrel is composed of a conical inlet section with a taper of γ and an outer diameter of Φ ₂ and a length of L. 10 . ₂ is composed of cylindrical sizing sections. The selection range of process parameters is: L ₂ =0.1-1mm, γ=10-30°; the range of the length L ₁ of the sizing section of the first special-shaped mold, the second special-shaped mold, and the third special-shaped mold is: L ₁ =0.5～5mm. 10. A cladding tube with straight ribs, characterized in that, the cladding tube with straight ribs is made by the multi-pass drawing forming process of the cladding tube with straight ribs as claimed in any one of claims 1-9. Therefore, the rib height of the cladding tube with straight ribs is greater than or equal to the wall thickness of the cladding tube with straight ribs.

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