A high-precision three-roller wall reduction and leveling device and process

Abstract

The present invention discloses a high-precision three-roller wall reduction and leveling device, comprising rollers, guide plates, and mandrels. The three rollers are all active rollers, and a guide plate is provided between adjacent rollers. The mandrel is located in a forming space surrounded by the guide plates and the rollers. The end of the mandrel with a smaller diameter is the feed end, and the billet enters the forming space from the smaller end of the mandrel. The present invention also provides a high-precision three-roller wall reduction and leveling process. Utilizing the above-mentioned high-precision three-roller wall reduction and leveling device, after the billet contacts the rollers, it spirals forward along the direction of the rolling line. Under the joint action of the rollers and the mandrel, the wall reduction and leveling rolling process is achieved, and the billet is output from the end with a larger diameter of the mandrel to complete the rolling of the seamless pipe. The present invention utilizes the guide plates to cooperate with the rollers to confine the billet within the forming space. The rollers and the mandrel cooperate to complete the wall reduction and leveling process in one pass, thereby increasing the rolling speed and avoiding the accumulation of forming errors caused by the long rolling process, thereby improving the precision and production efficiency of the seamless pipe product.

Description

Technical Field

[0001] This invention relates to the field of seamless pipe forming technology, and in particular to a high-precision three-roll wall reduction and equalization device and process. Background Technology

[0002] Seamless pipes have been increasingly widely used in various fields such as oil extraction, drilling, aerospace, and military industries in recent years due to their excellent mechanical properties and stability.

[0003] The hot-rolled seamless steel pipe continuous rolling mill technology is a technology that processes solid billets into seamless steel pipes. The general process flow of the production equipment is as follows: billet heating - piercing mill to produce a rough tube - PQF (Premium Quality Finishing, a three-roll limited-movement mandrel continuous rolling mill developed by MEER-INNSE) three-roll continuous rolling mill wall reduction and extension to produce a blank tube - sizing mill to round and sizing the circumference of the blank tube. In actual production, due to the original assembly accuracy of the rolling mill and fatigue and wear during continuous use, the wall thickness of the rough tube cannot be uniform, and the wall thickness accuracy decreases.

[0004] Chinese patent CN215998069U discloses a three-roll continuous rolling mill for improving the uniformity of seamless steel pipe wall thickness. However, this mill has many production processes and a large number and variety of equipment, which makes it difficult to adjust product specifications and results in low production efficiency.

[0005] The utility model patents CN217070184U ("Guide Plate and Guide Roll Adjustment Mechanism for Three-Roll Hot Rolling Mill"), CN201399469Y ("A Three-Roll Skew Rolling Mill"), and CN101912878A ("An Open Stand Three-Roll Skew Rolling Extension Mill") only involve the equipment itself. They do not address the issue of uneven axial deformation of finished parts, dimensional accuracy, shear deformation, grain refinement, or improved microstructure by changing the deformation zone structure and segmented mandrel design.

[0006] Therefore, the existing seamless pipe manufacturing process has the following main problems in the production process: (1) The hot-rolled seamless steel pipe production process involves many steps, various types of equipment, the longest production line, and a complex equipment layout. During the production process, errors gradually accumulate in each pass, making the final product unable to meet the specifications. (2) At present, in order to improve the wall thickness accuracy and ensure product quality, the continuous rolling mill of seamless steel pipe mainly optimizes and improves the assembly, maintenance and upkeep of the main equipment of the continuous rolling mill. However, since the continuous rolling mill is a continuous assembly line operation, fatigue and wear of the equipment are inevitable. The improvement of the wall thickness accuracy of seamless steel pipe often hits a bottleneck and it is difficult to achieve a major breakthrough, which seriously affects the production of seamless steel pipe with strict requirements for wall thickness accuracy. (3) There is no approach to solving the problems of substandard accuracy and poor performance in the production of seamless steel pipe by changing the deformation zone structure and the segmented mandrel design.

[0007] Therefore, how to change the current situation where the production efficiency of seamless pipes is low and the cumulative error affects the product accuracy has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a high-precision three-roll wall reduction and equalization device and process to solve the problems existing in the prior art, improve the forming accuracy of seamless tubes, and improve the efficiency of seamless tube formation.

[0009] To achieve the above objectives, the present invention provides the following solution: The present invention provides a high-precision three-roll wall-reducing and leveling device, comprising:

[0010] The rolling mill has three rolls, with the rolling line being the straight line in which the billet moves during rolling. The three rolls are evenly distributed around the rolling line. The rolls are rotating bodies with unequal diameters, and the smaller diameter ends of the three rolls are located at the same end. The rolls can rotate around their own axes.

[0011] A guide plate is located between adjacent rolls, and the rolls rotatably abut against the guide plate. There are three guide plates, which are evenly distributed around the circumference of the rolling line.

[0012] The mandrel is located within the forming space enclosed by the roll and the guide plate. The forming space is cylindrical, and the axis of the mandrel coincides with the rolling line. The mandrel is a rotating body with unequal diameters, and the opening of the forming space near the smaller diameter end of the mandrel is the feed port.

[0013] Preferably, the three rollers are of the same size;

[0014] The smaller diameter end of the mandrel is located at the smaller diameter end of the roll; or, the smaller diameter end of the mandrel is located at the larger diameter end of the roll.

[0015] Preferably, the rolls include a first roll and a second roll, with two first rolls and one second roll. The first rolls and the second roll have the same shape and the two first rolls have the same size. The first rolls and the second roll are cut along the same plane parallel to the radial direction of the rolls. The diameter of the first roll is smaller than the diameter of the second roll. The smaller diameter ends of the first rolls and the second rolls are located closer to the smaller diameter end of the top head.

[0016] Preferably, the unit pitch t of the rolled piece is:

[0017] t=π·η0·D·tgβ

[0018] Wherein, β is the feed angle;

[0019] D—the diameter of the blank;

[0020] η0—Axial slip coefficient at the exit point;

[0021] Along the rolling line direction, the mandrel includes a preparation section, a wall reduction section, a leveling section, and a guide section connected in sequence, and the diameters of the preparation section, the wall reduction section, and the leveling section increase sequentially. The axial length of the preparation section is 0.4 to 0.6 t, the axial length of the leveling section is 2.0 to 2.5 t, and the axial length of the guide section is 0.9 to 1.1 t.

[0022] Preferably, the minimum diameter of the preparation section is 2R1, the diameter at the connection between the preparation section and the wall reduction section is 2R2, the wall reduction section includes a first wall reduction section and a second wall reduction section, the preparation section is connected to the first wall reduction section, the diameter at the connection between the first wall reduction section and the second wall reduction section is 2R3, the second wall reduction section is connected to the leveling section, the diameter at the connection between the leveling section and the circular section is 2R4, the wall reduction amount of the first wall reduction section is ΔS1, the wall reduction amount of the second wall reduction section is ΔS2, and the total wall reduction amount of the wall reduction section is ΔS.

[0023] ΔS=ΔS1+ΔS2

[0024]

[0025] Wherein, D is the diameter of the billet;

[0026] S—the wall thickness of the blank;

[0027] I — the amount of reduction of the rolled piece;

[0028] The reduction I of the rolled piece is 17% to 21%, and the reduction W before the mandrel is 16% to 20%.

[0029] △S1 / △S2=0.5~2.

[0030] Preferably, the outer walls of both the wall-reducing section and the circular section are arc surfaces.

[0031] Preferably, the roll includes a first roll body and a second roll body, wherein the larger diameter end of the first roll body is connected to the smaller diameter end of the second roll body to form a roll throat, the ratio of the diameter of the roll throat to the diameter of the billet is 1 to 3, the ratio of the axial length of the roll to the diameter of the roll throat is 1.5 to 3.5, the ratio of the axial length of the first roll body to the axial length of the second roll body is 3:5, the roll surface cone angle is 3.5° to 5°, and the rolling angle of the roll is 11° to 13°.

[0032] Preferably, the connection between the first roller body and the second roller body is rounded, and the chamfer radius is not less than 500mm.

[0033] This invention also provides a high-precision three-roll wall reduction and equalization process. Utilizing the aforementioned high-precision three-roll wall reduction and equalization device, the three rolls rotate at the same speed around their respective axes. Along the direction from the smaller diameter end to the larger diameter end of the mandrel, the billet enters the forming space. The billet contacts the rolls and spirals forward along the rolling line. After contacting the mandrel, the billet continues to feed, achieving wall reduction and equalization rolling. The billet is output through the gap between the rolls, the guide plate, and the mandrel, completing the rolling process.

[0034] Preferably, the billet is heated before rolling.

[0035] Compared with the prior art, the present invention has achieved the following technical effects:

[0036] This invention relates to a high-precision three-roll wall reduction and equalization device, in which all three rolls are active rolls. Guide plates are positioned between adjacent rolls, and a mandrel is located within the forming space enclosed by the guide plates and rolls. The smaller diameter end of the mandrel serves as the feed end, through which the billet enters the forming space. After contacting the rolls, the billet spirals forward along the rolling line. Upon encountering the mandrel, the billet undergoes wall reduction and equalization rolling under the combined action of the rolls and the mandrel, finally exiting from the larger diameter end of the mandrel, completing the rolling of the seamless tube. In this forming device, all three rolls are active rolls, promoting the forward flow of the billet metal along the rolling line. Simultaneously, the guide plates, in conjunction with the rolls, confine the billet within the forming space. The rolls and mandrel work together to complete the wall reduction and equalization processes in a single pass, increasing rolling speed and avoiding the accumulation of forming errors caused by long rolling processes, thus improving the precision and production efficiency of seamless tube products.

[0037] This invention also provides a high-precision three-roll wall reduction and equalization process. Utilizing the aforementioned high-precision three-roll wall reduction and equalization device, three rolls rotate at the same speed around their respective axes. Along the direction from the smaller diameter end of the mandrel to the larger diameter end, the billet enters the forming space, contacts the rolls, and spirals forward along the rolling line. After contacting the mandrel, the billet continues to feed, achieving wall reduction and equalization rolling. The billet is output through the gap between the rolls, guide plates, and mandrel, completing the rolling process. This high-precision three-roll wall reduction and equalization process utilizes the forming space formed by the rolls and guide plates in conjunction with the mandrel to complete the billet rolling in one pass, avoiding the error accumulation caused by multiple rolling passes. This improves both rolling accuracy and the efficiency of seamless tube forming. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a front view schematic diagram of the high-precision three-roll wall reduction and equalization device in Embodiment 1 of the present invention;

[0040] Figure 2 This is a side view schematic diagram of the high-precision three-roll wall reduction and equalization device in Embodiment 1 of the present invention;

[0041] Figure 3 This is a schematic diagram of the cross-sectional structure of the top head of the high-precision three-roll wall reduction and equalization device of the present invention;

[0042] Figure 4 This is a schematic diagram of the cross-sectional structure of the rolls in the high-precision three-roll wall-reducing and leveling device of the present invention;

[0043] Figure 5 This is a schematic diagram of the high-precision three-roll wall-reducing and leveling device in Embodiment 2 of the present invention;

[0044] Figure 6 This is a front view schematic diagram of the high-precision three-roll wall reduction and equalization device in Embodiment 3 of the present invention;

[0045] Figure 7 This is a side view schematic diagram of the high-precision three-roll wall reduction and equalization device in the third embodiment of the present invention.

[0046] Wherein, 1 is the rolling mill roll, 101 is the first rolling mill body, 102 is the second rolling mill body, 2 is the guide plate, 3 is the top head, 301 is the preparation section, 302 is the wall reduction section, 303 is the leveling section, 304 is the rounding section, 4 is the first rolling mill roll, and 5 is the second rolling mill roll. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The purpose of this invention is to provide a high-precision three-roll wall reduction and equalization device and process to solve the problems existing in the prior art, improve the forming accuracy of seamless tubes, and improve the efficiency of seamless tube formation.

[0049] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] This invention provides a high-precision three-roll wall reduction and equalization device, comprising rolls 1, guide plates 2, and a mandrel 3. The number of rolls 1 is three, with the rolling line being the straight line along which the billet moves during rolling. The three rolls 1 are evenly distributed around the rolling line. The rolls 1 are unequal-diameter rotating bodies, and the smaller diameter ends of the three rolls 1 are located at the same end. Each roll 1 can rotate around its own axis. The guide plates 2 are located between adjacent rolls 1, and the rolls 1 rotatably abut against the guide plates 2. There are three guide plates 2, evenly distributed around the rolling line. The mandrel 3 is located within the forming space enclosed by the rolls 1 and guide plates 2. The forming space is cylindrical, and the axis of the mandrel 3 coincides with the rolling line. The mandrel 3 is also an unequal-diameter rotating body, and the opening of the forming space closest to the smaller diameter end of the mandrel 3 serves as the feed inlet.

[0051] The high-precision three-roll wall reduction and equalization device of the present invention comprises three active rolls 1, with guide plates 2 positioned between adjacent rolls 1. A mandrel 3 is located within the forming space enclosed by the guide plates 2 and the rolls 1. The smaller diameter end of the mandrel 3 serves as the feed end, through which the billet enters the forming space. After contacting the rolls 1, the billet spirals forward along the rolling line. Upon encountering the mandrel 3, the billet undergoes wall reduction and equalization rolling under the combined action of the rolls 1 and the mandrel 3, finally exiting from the larger diameter end of the mandrel 3, thus completing the rolling of the seamless tube. In this forming device, all three rolls 1 are active rolls, promoting the forward flow of the billet metal along the rolling line. Simultaneously, the guide plates 2, in conjunction with the rolls 1, confine the billet within the forming space. The rolls 1 and the mandrel 3 work together to complete the wall reduction and equalization processes in a single pass, increasing rolling speed and avoiding the accumulation of forming errors caused by long rolling processes, thereby improving the precision and production efficiency of seamless tube products. It should also be explained here that both the guide plate 2 and the mandrel 3 can be connected to other parts of the rolling equipment to prevent misalignment during the rolling process from affecting the normal production of seamless tubes.

[0052] This invention also provides a high-precision three-roll wall reduction and equalization process. Utilizing the aforementioned high-precision three-roll wall reduction and equalization device, three rolls 1 rotate at the same speed around their respective axes. Along the direction from the smaller diameter end to the larger diameter end of the mandrel 3, the billet enters the forming space, contacts the rolls 1, and spirals forward along the rolling line. After contacting the mandrel 3, the billet continues to feed, achieving wall reduction and equalization rolling. The billet is output through the gap between the rolls 1, guide plate 2, and mandrel 3, completing the rolling process. This invention's high-precision three-roll wall reduction and equalization process utilizes the forming space formed by the rolls 1 and guide plate 2, in conjunction with the mandrel 3, to complete the billet rolling in one pass, avoiding the error accumulation caused by multiple rolling passes. This improves both rolling accuracy and the efficiency of seamless tube forming.

[0053] In actual production, the billet is heated before rolling to ensure that it can be successfully formed.

[0054] The high-precision three-roll wall-reducing and leveling device of the present invention will be further explained and described below through specific embodiments.

[0055] Example 1

[0056] In this embodiment, the three rollers 1 are of the same size. The smaller diameter end of the mandrel 3 is located at the smaller diameter end of the roller 1. The smaller diameter end of the mandrel 3 is the feed end, that is, the opening formed by the smaller diameter end of the roller 1 and the guide plate 2 is the feed inlet of the forming space. Figure 1 As shown.

[0057] The unit pitch t of the rolled piece is:

[0058] t=π·η0·D·tgβ

[0059] In the formula, β is the feed angle;

[0060] D—Diameter of the billet;

[0061] η0—Axial slip coefficient at the exit point;

[0062] Specifically, along the rolling line direction, see details. Figure 3 The top head 3 includes a preparation section 301, a wall reduction section 302, a leveling section 303, and a guide section 304 connected in sequence. The diameters of the preparation section 301, the wall reduction section 302, and the leveling section 303 increase in sequence. The axial length L1 of the preparation section 301 is 0.4 to 0.6t, the axial length L4 of the leveling section 303 is 2.0 to 2.5t, and the axial length L5 of the guide section 304 is 0.9 to 1.1t.

[0063] The minimum diameter of the preparation section 301 is 2R1, and the diameter at the connection between the preparation section 301 and the wall reduction section 302 is 2R2. The wall reduction section 302 includes a first wall reduction section 302 and a second wall reduction section 302. The preparation section 301 is connected to the first wall reduction section 302, and the diameter at the connection between the first wall reduction section 302 and the second wall reduction section 302 is 2R3. The second wall reduction section 302 is connected to the leveling section 303, and the diameter at the connection between the leveling section 303 and the circular section 304 is 2R4.

[0064] It should also be noted that, when the mandrel 3 is axially sectioned, the intersection of the connecting surface of the leveling section 303 and the guide circle section 304 with the axis of the mandrel 3 is a6. At point a6, the inner diameter of the target seamless tube is 2R4. Concentric circles are drawn with a as the center. The intersection of concentric circle one with the outer contour line of the axial section of the leveling section 303 is a4. The diameter of concentric circle one is:

[0065] φ1=D-2S

[0066] In the formula, D is the diameter of the billet;

[0067] S—wall thickness of the billet;

[0068] Along the direction opposite to the billet feed direction, at 10mm intervals, a radial section 303 perpendicular to the rolling line design mandrel 3 is formed. This radial section is circular, and the circular section is tangent to roll 1, forming two concentric circles. The intersection point of concentric circle two and the outer contour line of the axial section of the leveling section 303 is a5. The diameter of concentric circle two is:

[0069] φ2=φ2-2S

[0070] In the formula, S represents the wall thickness of the billet;

[0071] Similarly, the radial cross-sectional circle of the leveling section 303 is designed every 10mm until the connection between the leveling section 303 and the wall reduction section 302 is reached. The outer wall of the leveling section 303 is smoothly transitioned, connecting the outlines of each cross-sectional circle. That is, the leveling section 303 achieves the sweeping of each cross-sectional circle along the axis of the top head 3, thus forming the leveling section 303.

[0072] The wall reduction amount of the first wall reduction section 302 is △S1, the wall reduction amount of the second wall reduction section 302 is △S2, and the total wall reduction amount of the wall reduction section 302 is △S.

[0073] ΔS=ΔS1+ΔS2

[0074]

[0075] Where D is the diameter of the billet;

[0076] S—wall thickness of the billet;

[0077] I – The amount of reduction in the rolled piece;

[0078] The reduction I of the rolled piece is 17% to 21%, and the reduction W before the mandrel is 16% to 20%.

[0079] △S1 / △S2=0.5~2.

[0080] The outer walls of both the reduced wall section 302 and the circular section 304 are curved surfaces.

[0081] After determining the dimension R3 at the connection between the first wall reduction section 302 and the second wall reduction section 302, the intersection point a3 of the outer wall contour lines of the axial sections of the first wall reduction section 302 and the second wall reduction section 302 can be determined. The outer wall contour line of the axial section of the second wall reduction section 302 is an arc passing through points a3 and a4. The distance between the projections of points a3 and a4 on the axis of the top head 3 is the axial length L3 of the second wall reduction section 302, and this arc is tangent to the straight line determined by points a4 and a5.

[0082] When determining the outer wall contour of the axial section of the first wall reduction section 302, a cylinder with dimensions D×W is determined with the rolling line as the axis. The position where the cylinder just contacts the roll 1 is determined, and the axial length L2 of the first wall reduction section 302 can be determined. The arc passing through points a3 and a4 is extended to determine the intersection point a2 of the outer wall contour of the axial section of the first wall reduction section 302 and the preparation section 301.

[0083] The top head 3 of the present invention adopts a four-segment design, wherein the leveling segment 303 is significantly extended, which has the obvious advantage of improving the dimensional accuracy of the finished part.

[0084] More specifically, if Figure 4As shown, the roll 1 includes a first roll body 101 and a second roll body 102. The larger diameter end of the first roll body 101 is connected to the smaller diameter end of the second roll body 102 to form a roll throat. The ratio of the diameter R5 of the roll throat to the diameter D of the billet is 1 to 3. The ratio of the axial length of the roll 1 to the diameter of the roll throat is 1.5 to 3.5. The ratio of the axial length L6 of the first roll body 101 to the axial length L7 of the second roll body 102 is 3:5. The roll surface cone angles of the roll 1 (the roll surface cone angle γ1 of the first roll body 101 and the roll surface cone angle γ2 of the second roll body 102) are 3.5° to 5°, and the rolling angle γ3 of the roll 1 is 11° to 13°. In practical applications, appropriate roll 1 parameters can be selected according to specific working conditions and forming requirements.

[0085] The connection between the first roller body 101 and the second roller body 102 is rounded, and the chamfer radius R6 is not less than 500mm, which helps to improve the forming accuracy of seamless tubes.

[0086] Example 2

[0087] In this embodiment, the three rollers 1 are of the same size, and the smaller diameter end of the mandrel 3 is located at the larger diameter end of the roller 1. The smaller diameter end of the mandrel 3 is still the feed end, meaning the opening formed by the larger diameter end of the roller 1 and the guide plate 2 is the feed inlet of the forming space. Figure 5 As shown, when the smaller diameter end of the mandrel 3 is positioned at the larger diameter end of the roll 1, the defect of uneven axial deformation of the finished part can be improved, and the dimensional accuracy of the finished part can be increased.

[0088] In practical applications, the setting direction of the mandrel 3 can be selected according to the specific working conditions, the specifications of the seamless tube and the blank, thereby improving the flexibility and adaptability of the forming device.

[0089] The structure of the top head 3 and the roll 1 is the same as in Example 1.

[0090] Example 3

[0091] In this embodiment, the rolls 1 are configured with different sizes. Each roll 1 includes a first roll 4 and a second roll 5. There are two first rolls 4 and one second roll 5. The first rolls 4 and the second roll 5 have the same shape and the same dimensions. The first rolls 4 and the second roll 5 are cut along the same plane parallel to the radial direction of the roll 1. The diameter of the first roll 4 is smaller than the diameter of the second roll 5. In other words, two small rolls 1 and one large roll 1 are provided. Figure 6 and Figure 7As shown, at this time, the smaller diameter ends of the first roll 4 and the second roll 5 are positioned close to the smaller diameter end of the top head 3, that is, the opening formed by the smaller diameter end of the roll 1 and the guide plate 2 is the feed inlet of the forming space. Using a large-size roll 1 and two small-size rolls 1 of the same shape can increase the shear deformation of the finished part, refine the grains, and improve the microstructure properties.

[0092] The structure of the top head 3 is the same as that in Example 1.

[0093] The high-precision three-roll wall reduction and leveling device of the present invention comprises three active rolls 1, with guide plates 2 arranged between adjacent rolls 1. The mandrel 3 is located within the forming space enclosed by the guide plates 2 and the rolls 1. The smaller diameter end of the mandrel 3 is the feeding end. The billet enters the forming space from the smaller diameter end of the mandrel 3. After the billet contacts the rolls 1, it spirals forward along the direction of the rolling line. After the billet encounters the mandrel 3, the wall reduction and leveling rolling process is realized in one pass under the combined action of the rolls 1 and the mandrel 3, reducing error accumulation and improving rolling efficiency.

[0094] Definitions:

[0095] Ellipticity: The ratio of the diameters of the inscribed circles of the three guide plates to the diameters of the inscribed circles of the three rolls within a cross section with the rolling line as the normal.

[0096] Feed angle: The feed angle refers to the angle between the horizontal projection of the roll axis and the rolling line on the horizontal cross section passing through the rolling line.

[0097] Rolling angle: The rolling angle refers to the angle between the vertical projection of the roll axis and the rolling line on the vertical section passing through the rolling line.

[0098] Roll surface cone angle: The roll surface cone angle refers to the angle between the generatrix of a frustum-shaped roll and the rolling line on any cross section passing through the roll axis.

[0099] Rolling line: The center line around which the three rolls are arranged.

[0100] Pitch: The axial displacement of a rolled piece during the time it takes for it to come into contact with one of the rolls at a certain point.

[0101] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A high-precision three-roll wall-reducing and leveling device, characterized in that, include: The rolling mill has three rolls, with the rolling line being the straight line in which the billet moves during rolling. The three rolls are evenly distributed around the rolling line. The rolls are rotating bodies with unequal diameters, and the smaller diameter ends of the three rolls are located at the same end. The rolls can rotate around their own axes. A guide plate is located between adjacent rolls, and the rolls rotatably abut against the guide plate. There are three guide plates, which are evenly distributed around the circumference of the rolling line. The mandrel is located within the forming space enclosed by the roll and the guide plate. The forming space is cylindrical, and the axis of the mandrel coincides with the rolling line. The mandrel is a rotating body structure with unequal diameters. The opening of the forming space near the smaller diameter end of the mandrel is the feed port. The three rollers rotate at the same speed around their respective axes. The billet enters the forming space along the direction from the smaller diameter end to the larger diameter end of the mandrel. The billet contacts the rollers and spirals forward along the direction of the rolling line. After contacting the mandrel, the billet continues to be fed to achieve wall reduction and leveling rolling. The billet is output through the gap between the rollers, the guide plate, and the mandrel, completing the rolling process.

2. The high-precision three-roll wall-reducing and leveling device according to claim 1, characterized in that: The three rollers are of the same size; The smaller diameter end of the mandrel is located at the smaller diameter end of the roll; or, the smaller diameter end of the mandrel is located at the larger diameter end of the roll.

3. The high-precision three-roll wall-reducing and leveling device according to claim 1, characterized in that: The rolls include a first roll and a second roll. There are two first rolls and one second roll. The first rolls and the second roll have the same shape and the two first rolls have the same size. The first rolls and the second roll are cut along the same plane parallel to the radial direction of the rolls. The diameter of the first roll is smaller than the diameter of the second roll. The smaller diameter ends of the first rolls and the second rolls are located closer to the smaller diameter ends of the top head.

4. The high-precision three-roll wall-reducing and leveling device according to claim 1, characterized in that, The unit pitch t of the rolled piece is: t=π·η0·D·tgβ Wherein, β is the feed angle; D—the diameter of the blank; η0—Axial slip coefficient at the exit point; Along the rolling line direction, the mandrel includes a preparation section, a wall reduction section, a leveling section, and a guide section connected in sequence, and the diameters of the preparation section, the wall reduction section, and the leveling section increase sequentially. The axial length of the preparation section is 0.4 to 0.6 t, the axial length of the leveling section is 2.0 to 2.5 t, and the axial length of the guide section is 0.9 to 1.1 t.

5. The high-precision three-roll wall-reducing and leveling device according to claim 4, characterized in that: The minimum diameter of the preparation section is 2R1, and the diameter at the connection between the preparation section and the wall reduction section is 2R2. The wall reduction section includes a first wall reduction section and a second wall reduction section. The preparation section is connected to the first wall reduction section, and the diameter at the connection between the first and second wall reduction sections is 2R3. The second wall reduction section is connected to the leveling section, and the diameter at the connection between the leveling section and the circular section is 2R4. The wall reduction amount of the first wall reduction section is ΔS1, the wall reduction amount of the second wall reduction section is ΔS2, and the total wall reduction amount of the wall reduction section is ΔS. ΔS=ΔS1+ΔS2 Wherein, D is the diameter of the billet; S—the wall thickness of the blank; I — the amount of reduction of the rolled piece; The reduction I of the rolled piece is 17% to 21%, and the reduction W before the mandrel is 16% to 20%. △S1 / △S2=0.5~2.

6. The high-precision three-roll wall-reducing and leveling device according to claim 5, characterized in that: The outer walls of both the wall-reducing section and the circular section are curved surfaces.

7. The high-precision three-roll wall-reducing and leveling device according to claim 1, characterized in that: The roll includes a first roll body and a second roll body. The larger diameter end of the first roll body is connected to the smaller diameter end of the second roll body to form a roll throat. The ratio of the diameter of the roll throat to the diameter of the billet is 1 to 3. The ratio of the axial length of the roll to the diameter of the roll throat is 1.5 to 3.

5. The ratio of the axial length of the first roll body to the axial length of the second roll body is 3:

5. The roll surface cone angle is 3.5° to 5°. The rolling angle of the roll is 11° to 13°.

8. The high-precision three-roll wall-reducing and leveling device according to claim 7, characterized in that: The connection between the first roller body and the second roller body is rounded, with a chamfer radius of not less than 500mm.

9. The high-precision three-roll wall-reducing and leveling device according to claim 1, characterized in that: The billet is heated before rolling.

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