A semi-flexible corrugated tube continuous roll forming apparatus and method
By using the full-pass external roll forming technology, the problems of low continuous production efficiency and poor equipment compatibility of annular square wave corrugated pipes have been solved, enabling efficient and precise production of multiple product models that meet the requirements of flexibility and rigidity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YANSHAN UNIV
- Filing Date
- 2023-12-08
- Publication Date
- 2026-06-30
Smart Images
Figure CN117443985B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flexible pipe processing technology, and in particular to a semi-flexible corrugated pipe continuous roll forming apparatus and method. Background Technology
[0002] Stainless steel annular square corrugated pipe is a type of small-diameter stainless steel flexible metal hose, typically made from thin-walled stainless steel through rolling, welding, and spinning. The annular square corrugated pipe is a flexible metal hose with straight-edged square crests and semi-circular troughs. Due to the good rigidity of the square crests and the good flexibility of the semi-circular troughs, it is also called a semi-flexible corrugated hose. Because of its good flexibility, high rigidity, high pressure resistance, and material saving, it can be widely used as a flexible shielding layer for cables and optical fibers, or as a flexible conduit connector to withstand various pulse, torsional, and bending loads.
[0003] For example, Chinese patent CN112091027B discloses a roll forming machine for seamless thin-walled corrugated pipes of fixed length, including a frame, a traction unit, a forming unit, a discharge unit, an oil tank, a lubrication tank, and a central control system. The traction unit and forming unit are mounted on the frame, with the forming unit located between the traction unit and the feeding unit. The seamless thin-walled pipe enters the forming unit through the traction unit for roll forming, and the formed corrugated pipe is discharged as a finished product through the discharge unit. However, this technical solution is only suitable for the production of seamless corrugated pipes and hoses of fixed length. Due to the use of a single forming unit, the forming efficiency is low and continuous production cannot be achieved.
[0004] Chinese patent CN114589225A discloses a corrugated pipe forming device, including a support block, a bearing, a mold, and a fastening ring. The support block is powered by a rotary motor, and the outer ring of the bearing is embedded in the support block. The pressure of the mold can be controlled by adjusting screws inside the support block. The mold is embedded in the inner ring of the bearing, and the rotary motor drives the support block to rotate, achieving both self-rotation and circumferential rotation forming around the inner diameter of the hose. However, this patent's technical solution is a single-mold internal spin forming, mainly targeting small-diameter double-arc corrugated hoses, resulting in limited product models and low efficiency and precision.
[0005] Chinese patent CN107755497B discloses a metal sheath corrugating machine, including a cutter head, guide rod, sliding cutter holder, rotating shaft, corrugating cutter, and pusher. Cable or optical cable sheaths enter the corrugating unit through a guide unit. The forming cutter head rotates around the cable sheath under the drive of a rotary motor. The corrugating cutter, adjusted according to the required corrugation depth, rolls a corrugated tubular shape onto the cable sheath. However, this patent's technical solution also uses a single-mold internal spinning mode for corrugation forming, primarily targeting cable sheath corrugation, and thus suffers from insufficient rolling precision.
[0006] Chinese patent CN113319149B discloses an integrated forming equipment for producing annular corrugated metal pipes, comprising a feeding machine, a welding machine, a traction machine, a forming machine, a shaping machine, a cleaning machine, and a receiving machine arranged sequentially. Steel strips are placed on the feeding machine, gradually rolled into round tubes by a rolling device, then welded into seam welded pipes by the welding machine. The strips are then sequentially fed into the forming and shaping machines by the traction device, and the entire process is completed through cleaning and rewinding of the finished products. This scheme uses internal spinning forming for the first three passes and three-roll external rolling forming for the fourth pass. Although this technical solution represents a significant optimization compared to previous solutions, achieving online continuous forming and welding of corrugated metal pipes, it still does not propose or solve a method or implementation form for producing annular square corrugated pipes, and also suffers from the problem of product structure uniformity.
[0007] Chinese patent CN215355623U discloses a forming mold for producing annular metal bellows, comprising a housing, a chuck, jaws, and gradually tapered pitch rollers. After the annular initial-wave bellows enters the forming mold, it is spun into a standard annular metal bellows by three gradually tapered pitch rollers. This patent is a structural supplement to Chinese patent CN113319149B, which discloses an integrated forming device for producing annular metal bellows. Although this technical solution proposes external spinning forming with a gradually tapered mold, it does not provide a specific forming method or product structure, resulting in a relatively simple structural form.
[0008] Chinese patent CN114749555A discloses a metal hose forming device and its forming method, including a worktable, a rolling unit, a steel pipe rounding unit, a lubrication unit, a first shallow wave forming unit, a second shallow wave forming unit, a third shallow wave forming unit, a dense wave forming unit, and a high-pressure cleaning unit. This patent method is consistent with the principle of an integrated forming equipment for producing annular metal corrugated pipes disclosed in patent CN113319149B, but it suffers from drawbacks such as a single product structure and design primarily for products of specific diameters, failing to meet the production needs of annular square wave corrugated pipes of various specifications.
[0009] In summary, although existing technologies have proposed beneficial innovative solutions from multiple perspectives, most of them adopt internal spinning or internal and external composite spinning processes. While these technologies have solved the forming problems of ordinary rolled tubes and metal corrugated tubes to some extent, they have not achieved integrated production of annular square wave corrugated tubes, have not solved the core manufacturing process of square wave tubes, and have a single equipment or product structure that cannot be compatible with multiple product models. Furthermore, they have not considered the convenience of mold replacement. Summary of the Invention
[0010] To address the aforementioned problems, the present invention aims to provide a semi-flexible corrugated pipe continuous roll forming apparatus and method. It proposes for the first time a full-pass external roll forming technology, which can efficiently and effectively meet the production and manufacturing of square corrugated hoses under different operating conditions. It features high forming efficiency, good product precision, and can realize online integrated continuous forming and switching between multiple product models.
[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0012] The present invention proposes a continuous roll forming device for semi-flexible corrugated pipes, comprising a cold bending roll group, a welding unit, a traction unit, and a roll forming unit; the welding unit is correspondingly arranged above the exit side of the cold bending roll group; the traction unit is correspondingly arranged in front of the exit side of the cold bending roll group; the roll forming unit is correspondingly arranged in front of the exit side of the traction unit; the roll forming unit comprises three sets of primary rolling units and two sets of finishing rolling units arranged in sequence and evenly.
[0013] Furthermore, both the primary rolling unit and the finishing rolling unit are composed of three circumferentially distributed annular rolling dies, and the outer side of the rolling dies is surrounded by helical teeth for rolling corrugated tubes; the three circumferentially distributed rolling dies are all coaxially equipped with roller shafts at their axial center positions, and each roller shaft is coaxially equipped with a synchronous gear at its tail end. The three synchronous gears are connected by a synchronous belt to ensure the synchronous operation of the three rolling dies; and each roller shaft is connected to a rotary unit at its front end.
[0014] Furthermore, the outer spiral teeth of the rolling die of the primary rolling unit are all designed with 1.5 turns of equal pitch, equal tooth thickness and equal outer diameter.
[0015] Furthermore, the outer spiral teeth of the rolling dies of the finishing mill unit all adopt a combination design of 6 turns of variable pitch, variable tooth thickness and variable outer diameter; among them, the pitch of the outer spiral teeth of the rolling dies of the first set of finishing mill units shows a gradual decreasing trend, while the outer diameter and tooth thickness show a gradual increasing trend; the pitch and tooth thickness of the outer spiral teeth of the rolling dies of the second set of finishing mill units show a gradual decreasing trend, while the outer diameter shows a gradual increasing trend.
[0016] Furthermore, guide sleeves are provided on both the inlet and outlet sides of the primary rolling unit and the finishing rolling unit.
[0017] A method for continuous roll forming of semi-flexible corrugated pipe includes the following steps:
[0018] S1. Stainless steel strips are passed sequentially through a cold bending roller group and a welding unit to prefabricate thin-walled stainless steel longitudinal seam welded pipes online.
[0019] S2. The thin-walled stainless steel welded pipe is fed into the first set of initial rolling units through the traction unit, and the initial three-roll rolling of the thin-walled stainless steel pipe is carried out according to the predefined spiral curve screw teeth to preform a square tube blank.
[0020] S3. The square tube blank pre-formed in step S2 is fed into the second primary rolling unit and subjected to trough-deep rolling and crest extrusion according to the predefined spiral curve teeth to further pre-form the square tube blank.
[0021] S4. The square tube blank preformed in step S3 is sent into the third primary rolling unit, and the troughs and peaks are further pressed and extruded according to the predefined spiral curve teeth to further preform the square tube blank.
[0022] S5. The square tube blank pre-formed in step S4 is fed into the first set of precision rolling units. The tube blank is precision rolled and straightened according to the predefined spiral curve of variable outer diameter, variable pitch, and variable tooth thickness to form a dense square corrugated tube.
[0023] S6. The square wave tube blank formed by the precision rolling in step S5 is sent to the second precision rolling unit. The tube blank is then subjected to final precision rolling and straightening according to the predefined spiral curve teeth with variable outer diameter, variable pitch, and variable tooth thickness to form a precision square wave corrugated tube.
[0024] Furthermore, three circumferentially distributed rolling dies perform pure rolling spinning around the trough of the tube blank, and the forming speed, forming speed and subsequent forming speed have a linear matching relationship.
[0025] Furthermore, the three circumferentially distributed rolling dies revolve around the center of the tube blank, while each die rotates around its own dynamic centerline. In other words, the three rolling dies undergo an approximate planetary motion around the centerline of the tube blank. After each rolling die completes one rotation, the outer threads advance one revolution, completing one wave of spinning. Based on this motion law, the relationship between the forming head rotation speed and the forming speed can be derived:
[0026]
[0027] In the formula:
[0028] N n The rotational speed of the forming head in the nth pass is rpm;
[0029] D' n The outer diameter of the spiral tooth at the exit of the nth forming die is in mm;
[0030] P n The outlet bellows pitch for the nth pass is in mm.
[0031] d n The diameter of the corrugated pipe trough at the exit of the nth rolling die, in mm;
[0032] K is the slip coefficient, taken as K = 0.95-0.98;
[0033] V n The forming speed for the nth pass is m / min.
[0034] Furthermore, as the square corrugated tube progresses through each rolling pass, the corrugation pitch P1 gradually decreases, resulting in a relationship between the forming speed V1, the corrugation pitch P1, and the forming speed V of subsequent passes. n Wavelength P n The direct proportional relationship:
[0035]
[0036] In the above formula:
[0037] V1 is the first-pass corrugated pipe forming speed, in m / min;
[0038] P1 is the bellows pitch of the first exit bellows, in mm;
[0039] P n The outlet bellows pitch for the nth pass is in mm.
[0040] Compared with the prior art, the present invention has the following beneficial effects:
[0041] 1. By arranging and combining cold bending rollers, stainless steel strips can be quickly bent into the required round tube shape. When switching between welded pipes of different diameters, only the roller spacing of the cold bending pipe needs to be adjusted, which can greatly improve the mold changing efficiency.
[0042] 2. By arranging and setting the roll forming units throughout the entire process, the stability and continuity of the continuous forming process of the annular square wave corrugated pipe can be optimized to the greatest extent. While ensuring uniform stress on the corrugated pipe body during forming, a more refined, flexible, and automated forming effect can be achieved.
[0043] 3. Through the special arrangement and precise design of the primary rolling unit and the finishing rolling unit, the precise biting of the initial tube blank and the smooth roll extrusion of the annular square wave corrugated tube can be achieved. At the same time, the three-roll forming of the whole pass can also realize the straightening and rounding of the tube blank while the corrugated tube is being rolled.
[0044] 4. By selecting rolling dies with different parameters, corrugated pipes with different parameters can be quickly switched and produced online, and the device has good compatibility and versatility. Attached Figure Description
[0045] Figure 1 This is a schematic diagram of the overall structure of a semi-flexible corrugated tube continuous roll forming device proposed in this invention.
[0046] Figure 2 This is a schematic diagram illustrating the evolution of square wave corrugated pipes;
[0047] Figure 3 yes Figure 1 A three-dimensional structural diagram of the intermediate roll forming unit;
[0048] Figure 4 This is a schematic diagram of the rolling motion principle of the roll forming unit;
[0049] Figure 5 This is a schematic diagram of the helical teeth on the outside of the 1-3 pass rolling die;
[0050] Figure 6 This is a schematic diagram of the helical teeth on the outside of a 4-5 pass rolling die;
[0051] Figure 7 This is a schematic diagram of the initial rolling unit I.
[0052] Figure 8 This is a schematic diagram of the initial rolling unit II;
[0053] Figure 9 This is a schematic diagram of the primary rolling unit III;
[0054] Figure 10 This is a schematic diagram of the finishing mill unit I rolling process;
[0055] Figure 11 This is a schematic diagram of the finishing mill unit II rolling process;
[0056] Figure 12 This is a schematic diagram of the process for a continuous roll forming method for semi-flexible corrugated pipes proposed in this invention.
[0057] Figure 13 This is a schematic diagram showing different types of irregular square wave corrugated pipes achieved by adjusting the parameters of the rolling die. Detailed Implementation
[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0059] It should be noted that in the description of this invention, the terms "upper", "lower", "top", "bottom", "one side", "the other side", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not mean that the device or element must have a specific orientation, or be constructed and operated in a specific orientation.
[0060] The semi-flexible corrugated tube continuous rolling forming device proposed in this embodiment adopts a five-pass continuous rolling forming process, and the outer diameter D of the corrugated tube is... 51 =16.6mm, wave pitch P5=2.4mm, valley diameter d5=12.3mm, wall thickness δ5=0.15mm, welding speed V0=1.8m / min, outer diameter of welded pipe φ15.4mm, forming speed V5=0.67m / min. For example... Figure 1-4 As shown, the assembly specifically includes a cold bending roll group 2, a welding unit 10, a traction unit 3, and a roll forming unit. The welding unit 10 is positioned above the exit side of the cold bending roll group 2, and the stainless steel strip 1 is positioned at the entrance side of the cold bending roll group 2. The cold bending roll group consists of cold bending rolls arranged symmetrically on both sides. The traction unit 3 is positioned in front of the exit side of the cold bending roll group 2. The roll forming unit is positioned in front of the exit side of the traction unit 3. In this embodiment, the roll forming unit includes a primary rolling unit I5, a primary rolling unit II6, a primary rolling unit III7, a finishing rolling unit I8, and a finishing rolling unit II9 arranged linearly and uniformly in sequence.
[0061] Each primary rolling unit and finishing rolling unit consists of three circumferentially distributed annular rolling dies, namely rolling die I11, rolling die II12, and rolling die III13. The outer side of each rolling die is surrounded by helical teeth for rolling corrugated tubes. Roller shafts 14 are coaxially arranged at the axial center of each of the rolling dies I11, II12, and III13. Synchronous gears 15 are coaxially mounted at the tail end of each roller shaft 14. The three synchronous gears 15 are connected to each other via synchronous belts 16 to ensure the synchronicity of the operation of the three rolling dies. A rotary unit 17 is connected to the front end of each roller shaft 14. The rotary unit 17 is correspondingly arranged on the base 22.
[0062] In this embodiment, the outer spiral teeth of each rolling die in the primary rolling unit I5, primary rolling unit II6 and primary rolling unit III7 are designed with 1.5 turns of equal pitch, equal tooth thickness and equal outer diameter.
[0063] The outer spiral teeth of the rolling dies in finishing mill unit I8 and finishing mill unit II9 both adopt a combination design of 6 turns of variable pitch, variable tooth thickness and variable outer diameter; among them, the pitch of the outer spiral teeth of the rolling dies in finishing mill unit I8 gradually decreases, while the outer diameter and tooth thickness gradually increase; the pitch and tooth thickness of the outer spiral teeth of the rolling dies in finishing mill unit II9 gradually decrease, while the outer diameter gradually increases.
[0064] The inlet guide sleeve 20 is provided on the inlet side of each of the primary rolling unit I5, primary rolling unit II6, primary rolling unit III7, finishing rolling unit I8 and finishing rolling unit II9, and the outlet guide sleeve 21 is provided on the outlet side.
[0065] A method for continuous roll forming of semi-flexible corrugated pipes, such as Figure 12 As shown, it includes the following steps:
[0066] S1, such as Figure 1 As shown, stainless steel strip 1 is rolled into a circle by cold bending roll group 2 and welded by welding unit 10 to prefabricate thin-walled stainless steel longitudinal seam welded pipe online.
[0067] S2, such as Figure 7 As shown, the thin-walled stainless steel welded pipe 4 enters the primary rolling unit I5 at a speed of V0 = 1.8 m / min. Three circumferentially distributed rolling dies roll the inlet billet around the central axis O1--O1 of the thin-walled stainless steel welded pipe 4 at a rotation speed of N1 = 1106 rpm. During the forming process, the inlet guide sleeve 20 and the outlet guide sleeve 21 provide circumferential constraints on the billet to ensure forming accuracy. The outlet speed of the billet is V1 = 1.6 m / min. The initial square wave billet 41 can be obtained through the pre-rolling of the primary rolling unit I5. Its outer diameter D1 = 15.6 mm, wave pitch P1 = 5.7 mm, and valley diameter d1 = 14.7 mm. One wave can be formed after the rolling die rotates once.
[0068] S3, such as Figure 8 As shown, the initial square wave tube blank 41 formed in step S2 enters the primary rolling unit II6 at a speed of V1 = 1.6 m / min. Three circumferentially distributed rolling dies surround the tube blank's central axis O2--O2 at a rotation speed of N2 = 1178 rpm to perform a second rolling forming on the inlet tube blank 41. The corrugated tube exit speed V2 = 1.49 m / min. Through the rolling of the three rolls and the extrusion of two adjacent helical teeth, the corrugation pitch and the depth of the trough can be further increased. The square wave tube blank 42 formed after the second rolling has an outer diameter D2 = 15.7 mm, a corrugation pitch P2 = 5.3 mm, and a trough diameter d2 = 13.8 mm.
[0069] S4, such as Figure 9As shown, the square wave tube blank 42, after being formed in step S3, enters the primary rolling unit III7 at a speed of V2 = 1.49 m / min. Three circumferentially distributed rolling dies surround the tube blank's central axis O3--O3 at a rotation speed of N3 = 1264 rpm to perform a third rolling process on the inlet tube blank 42. The exit speed of the corrugated tube is V3 = 1.38 m / min. The corrugation of the tube blank formed by the third rolling process is further compressed, and the troughs are further deepened, thus preparing for the next step of precision rolling. The square wave tube blank 43 after the third rolling process has an outer diameter D3 = 15.8 mm, a corrugation P3 = 4.9 mm, and a trough diameter d3 = 12.9 mm.
[0070] S5, such as Figure 10 As shown, the tube blank 43 formed in step S4 enters the finishing rolling unit I8 at a speed of V3 = 1.38 m / min, and the exit tube blank 44 has a speed of V4 = 0.95 m / min. The spiral teeth on the outside of the rolling die have gradually changing tooth thickness, gradually changing tooth pitch, and gradually changing outer diameter. Through the fourth pass of finishing rolling and straightening, a more flexible square wave corrugated tube 44 is formed, with an outer diameter of D4 = 16.2 mm, a wave pitch of P4 = 3.4 mm, and a valley diameter of d4 = 12.6 mm.
[0071] S6, such as Figure 11 As shown, the tube blank 44 formed in step S5 enters the finishing rolling unit II9 at a speed of V4 = 0.95 m / min, and the exit tube blank 45 has a speed of V5 = 0.67 m / min. The spiral teeth on the outside of the rolling die have gradually changing tooth thickness, gradually changing tooth pitch, and gradually changing outer diameter. After the fifth pass of finishing rolling and straightening, the final dense-wave square-wave corrugated tube 45 is formed with an outer diameter of D5 = 16.6 mm, a wave pitch of P5 = 2.4 mm, and a valley diameter of d5 = 12.3 mm.
[0072] In the primary rolling unit and the finishing rolling unit, three circumferentially distributed rolling dies perform pure rolling spinning around the trough of the tube blank, and the forming speed, forming speed and subsequent forming speed have a linear matching relationship.
[0073] Three circumferentially distributed rolling dies revolve around the center of the tube blank, while each die rotates on its own axis. This results in an approximate planetary motion of the three dies around the tube blank's centerline. After each die completes one rotation, the outer threads advance one revolution, completing one wave of spinning. Based on this motion law, the relationship between the forming head rotation speed and the forming speed can be derived. The forming speed N... n With molding speed V n Control according to the following formula:
[0074]
[0075] In the formula:
[0076] N n The rotational speed of the forming head in the nth pass is rpm;
[0077] D' is the outer diameter of the spiral tooth at the exit of the nth forming die, in mm;
[0078] n
[0079] P n The outlet bellows pitch for the nth pass is in mm.
[0080] d n The diameter of the corrugated pipe trough at the exit of the nth rolling die, in mm;
[0081] K is the slip coefficient, taken as K = 0.95-0.98;
[0082] V n The forming speed for the nth pass is m / min.
[0083] As the square corrugated tube progresses through each rolling pass, the corrugation pitch P1 gradually decreases, resulting in a relationship between the forming speed V1, the corrugation pitch P1, and the forming speed V of subsequent passes. n Wavelength P n The direct proportional relationship is controlled by the following formula:
[0084]
[0085] In the formula:
[0086] V1 is the first-pass corrugated pipe forming speed, in m / min;
[0087] P1 is the bellows pitch of the first exit bellows, in mm;
[0088] P n The outlet bellows pitch for the nth pass is in mm.
[0089] Table 1. Dimensional parameters of bellows for each pass.
[0090]
[0091] Table 2 Parameters of the spiral teeth for 1-3 passes of rolling mill
[0092]
[0093] Table 3. Parameters of the spiral teeth for the fourth pass rolling die.
[0094]
[0095] Table 4. Parameters of the spiral teeth for the 5th rolling die
[0096]
[0097] Table 51-5 Relationship between Forming Speed and Rotation Speed per Pass
[0098]
[0099] Using the mold helical tooth parameters in Table 2-4 and the forming speed parameters in Table 5, the special corrugated pipe with square waves in Table 1 can be formed by following steps S1-S6 for pipe welding, traction, initial rolling, and fine rolling.
[0100] This embodiment only provides one type of annular square corrugated pipe forming assembly; more types of corrugated pipes can be formed by varying different parameters. For example... Figure 13 As shown, various irregular square wave corrugated pipes, such as one with a large square wave and one with a small square wave, or one with a large square wave and two small square waves, are provided to meet the needs of different working conditions.
[0101] All matters not covered in this invention are common knowledge.
[0102] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A semi-flexible bellows continuous roll forming apparatus, characterized by: The device includes a cold bending roll group, a welding unit, a traction unit, and a roll forming unit; the welding unit is correspondingly located above the exit side of the cold bending roll group; the traction unit is correspondingly located in front of the exit side of the cold bending roll group; the roll forming unit is correspondingly located in front of the exit side of the traction unit; the roll forming unit includes three sets of primary rolling units and two sets of finishing rolling units arranged in sequence and evenly. Both the primary rolling unit and the finishing rolling unit consist of three circumferentially distributed annular rolling dies, and the outer side of the rolling dies is surrounded by helical teeth for rolling corrugated tubes; the three circumferentially distributed rolling dies are all coaxially equipped with roller shafts at their axial center positions, and each roller shaft is coaxially equipped with a synchronous gear at its tail end. The three synchronous gears are connected by a synchronous belt to ensure the synchronous operation of the three rolling dies; and each roller shaft is connected to a rotary unit at its front end. The outer spiral teeth of the rolling die of the primary rolling unit are all designed with 1.5 turns of equal pitch, equal tooth thickness and equal outer diameter; The outer spiral teeth of the rolling dies in the finishing mill unit all adopt a combination design of 6 turns of variable pitch, variable tooth thickness and variable outer diameter; among them, the pitch of the outer spiral teeth of the rolling dies in the first set of finishing mill units shows a gradual decreasing trend, while the outer diameter and tooth thickness show a gradual increasing trend; the pitch and tooth thickness of the outer spiral teeth of the rolling dies in the second set of finishing mill units show a gradual decreasing trend, while the outer diameter shows a gradual increasing trend.
2. A semi-flexible bellows continuous roll forming apparatus as defined in claim 1, wherein: Guide sleeves are provided on both the inlet and outlet sides of the primary rolling unit and the finishing rolling unit.
3. The method of claim 1, wherein the semi-flexible bellows is formed by continuously rolling the semi-flexible bellows in a shape of a cylindrical tube. Includes the following steps: S1. Stainless steel strips are passed sequentially through a cold bending roller group and a welding unit to prefabricate thin-walled stainless steel longitudinal seam welded pipes online. S2. The thin-walled stainless steel welded pipe is fed into the first set of initial rolling units through the traction unit, and the initial three-roll rolling of the thin-walled stainless steel pipe is carried out according to the predefined spiral curve screw teeth to preform a square tube blank. S3. The square tube blank pre-formed in step S2 is fed into the second primary rolling unit and subjected to trough-deep rolling and crest extrusion according to the predefined spiral curve teeth to further pre-form the square tube blank. S4. The square tube blank preformed in step S3 is sent into the third primary rolling unit, and the troughs and peaks are further pressed and extruded according to the predefined spiral curve teeth to further preform the square tube blank. S5. The square tube blank pre-formed in step S4 is fed into the first set of precision rolling units. The tube blank is precision rolled and straightened according to the predefined spiral curve of variable outer diameter, variable pitch, and variable tooth thickness to form a dense square corrugated tube. S6. The square wave tube blank formed by the precision rolling in step S5 is sent to the second precision rolling unit. The tube blank is then subjected to final precision rolling and straightening according to the predefined spiral curve teeth with variable outer diameter, variable pitch, and variable tooth thickness to form a precision square wave corrugated tube.
4. The forming method of the semi-flexible corrugated tube continuous roll forming device according to claim 3, characterized in that: Three circumferentially distributed rolling dies perform pure rolling spinning around the trough of the tube blank, and the forming speed, forming speed and subsequent forming speed have a linear matching relationship.
5. The forming method of a semi-flexible corrugated tube continuous roll forming device according to claim 3, characterized in that: Three circumferentially distributed rolling dies revolve around the center of the tube blank, while each die rotates around its own dynamic centerline. This means the three dies undergo an approximate planetary motion around the tube blank's centerline. After each die completes one rotation, the outer threads advance one revolution, completing one wave of spinning. Based on this motion law, the relationship between the forming head rotation speed and the forming speed can be derived: ； In the formula: The rotational speed of the forming head in the nth pass is rpm; The outer diameter of the spiral tooth at the exit of the nth forming die is in mm; The outlet bellows pitch for the nth pass is in mm. The diameter of the corrugated pipe trough at the exit of the nth rolling die, in mm; K The slip coefficient is taken as K = 0.95-0.98; The forming speed for the nth pass is m / min.
6. The forming method of a semi-flexible corrugated tube continuous roll forming device according to claim 5, characterized in that: As the square corrugated tube progresses through each rolling pass, the corrugation pitch of the corrugated tube increases. P 1. The speed gradually decreases as the rolling passes proceed, thus forming the forming speed. V 1. Wavelength P 1. Forming speed of subsequent passes V n Wavelength P n The direct proportional relationship: ; In the above formula: V 1 represents the first-pass corrugated pipe forming speed, in m / min; P 1 represents the corrugated pitch of the first exit bellows, in mm; P n The outlet bellows pitch for the nth pass is in mm.