A roller profile for reducing the internal thread of steel pipes rolled by Assel mill

Abstract

The present invention provides a roller profile for reducing the internal thread of a steel pipe rolled by an Assel unit. An entrance cone area, a shoulder area and a rolling area are sequentially arranged from the entrance side to the exit side of the roller. The entrance cone area consists of a first entrance cone area and a second entrance cone area, wherein the first entrance cone area is located between the second entrance cone area and the entrance end of the roller, wherein the ratio of the length of the first entrance cone area along the roller axis to the length of the second entrance cone area along the roller axis is 7:10, and the entrance cone angle α1 of the first entrance cone area differs from the entrance cone angle α2 of the second entrance cone area by 1°; the ratio of the length of the rolling area along the roller axis to the length of the second entrance cone area along the roller axis is 4:5; the present invention solves the technical problem that the spiral concave-convex phenomenon on the inner surface of a steel pipe affects the appearance of the steel pipe and seriously affects the use by users.

Description

Technical Field

[0001] The invention belongs to the field of tube rolling mill equipment, and in particular relates to a roller profile for reducing the internal thread of a steel tube rolled by an Assel unit. Background Art

[0002] The internal thread of the steel pipe is an inherent defect of the Assel rolling unit. The depth of the thread is different due to the different roll types. For example, the original Assel rolling mill roll type ( Figure 5 ) The inner surface of the rolled steel pipe has serious threads, with the thread depth reaching 0.5mm~0.8mm, and sometimes reaching 1.0~1.2mm. First, the inner surface presents spiral convexity and concaveness, which affects the appearance of the steel pipe. Second, it seriously affects the user's use (such as difficulty in cold drawing, knife hitting during machining, etc.). Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a roller profile for reducing the internal threads of steel pipes rolled by an Assel unit, thereby solving the technical problem that the spiral concave-convex phenomenon on the inner surface of the steel pipe affects the appearance of the steel pipe and seriously affects the use by users.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a roller profile for reducing the internal thread of a steel pipe rolled by an Assel unit, wherein an entrance cone zone, a shoulder zone, and a rolling zone are sequentially arranged from the entrance side to the exit side of the roller, the entrance cone zone consists of a first entrance cone zone and a second entrance cone zone, wherein the first entrance cone zone is located between the second entrance cone zone and the entrance end of the roller, wherein the ratio of the length of the first entrance cone zone along the roller axis to the length of the second entrance cone zone along the roller axis is 7:10, and the entrance cone angle α1 of the first entrance cone zone differs from the entrance cone angle α2 of the second entrance cone zone by 1°; the rolling zone is connected to the second entrance cone zone through the shoulder zone, and the ratio of the length of the rolling zone along the roller axis to the length of the second entrance cone zone along the roller axis is 4:5; the entrance cone angle α1 of the first entrance cone zone is the angle between the rolling center line of the roller and the surface of the first entrance cone zone, and the entrance cone angle α2 of the second entrance cone zone is the angle between the rolling center line of the roller and the surface of the second entrance cone zone. In the roller profile of this application example, preferably, the angle between the rolling center line of the roller and the axis of the roller is 4°, the length of the first entrance cone area along the axis of the roller is 70 mm; the length of the second entrance cone area along the axis of the roller is 100 mm.

[0005] In the roller profile of this application example, preferably, the inlet cone angle α1 of the first inlet cone zone is 6°, and the inlet cone angle α2 of the second inlet cone zone is 7°.

[0006] In the roller profile of this application example, preferably, the length of the rolling zone along the roller axis is 80 mm.

[0007] In the roller profile of this application example, preferably, the ratio of the length of the shoulder area along the axis of the roller to the length of the second entrance cone area along the axis of the roller is 8.48:100, and its radial height along the roller is 4.03 mm; the shoulder area is composed of a first arc connected to the second entrance cone area and a second arc connected to the rolling area, wherein the first arc is tangent to the second arc in the opposite direction, the radius of the first arc is 3.3 mm, and the radius of the second arc is 8 mm.

[0008] In the roller profile of this application example, preferably, knurling is provided on the inlet cone area, and the pitch of the knurling is 1.5 mm and the depth is 0.3 mm.

[0009] In the roller profile of this application example, preferably, the roller further includes an exit cone zone, the length of the exit cone zone along the roller axis is 155 mm, and the exit cone angle α3 thereof differs from the entry cone angle α1 by 4°.

[0010] By changing the length of the outlet cone area and the angle of the outlet cone angle α3, the diameter expansion amount inside the steel pipe is increased, so that the core rod can be easily pulled out of the steel pipe without causing the rod wrapping accident.

[0011] In the roller profile of this application example, preferably, the exit cone angle α3 is the angle between the rolling center line of the roller and the surface of the exit cone area, and the exit cone angle α3 is 2°.

[0012] In the roller profile of this application example, preferably, an outlet fillet area is provided between the outlet cone area and the rolling area, and the length of the outlet fillet area along the roller axis is 20.9 mm.

[0013] In the roller profile of this application example, preferably, a first rounded corner area is provided between the first inlet cone area and the inlet end of the roller, and a second rounded corner area is provided between the outlet cone area and the outlet end of the roller.

[0014] In the roller profile of this application example, preferably, the fillet radius of the first fillet area is 100 mm, and the fillet radius of the second fillet area is 30 mm.

[0015] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0016] Firstly, the present invention achieves the effect of uniform steel pipe wall thickness by slowly reducing the outer diameter of the steel pipe (air rolling), that is, resetting the length of the entrance cone zone and the angle of the entrance cone angle (according to the law of least resistance: when metal undergoes plastic deformation under the action of external force, each particle inside it always flows in the direction of least resistance). Secondly, the present invention solves the technical problem that the inner surface of the produced steel pipe presents spiral bumps, which affects the appearance of the steel pipe and seriously affects the use by users by resetting the length of the rolling zone and the length and height of the shoulder zone. Therefore, the quality of the steel pipe product produced by the present invention is recognized by users, and the market competitiveness of the steel pipe product produced by the present invention is further improved.

[0017] The present invention is to improve the original Assel roller profile ( Figure 5 ) was optimized and modified. The Assel roll profile after re-optimization and modification is as follows Figure 1 As shown, the optimization, improvement and effects of the present invention compared with the original Assel roll profile are as follows:

[0018] 1) Changing the inlet cone angle of the roll can better control the diameter reduction of the incoming steel pipe;

[0019] 2) Modifying the roller inlet cone length can better control the diameter reduction of the incoming steel pipe;

[0020] 3) Optimizing the height and length of the roller shoulder can better control the amount of steel pipe wall reduction and slowly reduce the wall thickness of the steel pipe;

[0021] 4) Changing the length of the rolling section can better allow the inner and outer surfaces and wall thickness of the steel pipe to be fully rolled;

[0022] 5) Changing the length and angle of the roller outlet cone can better increase the diameter expansion of the steel pipe, making it easier to pull the core rod out of the steel pipe without causing rod wrapping accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the present invention;

[0024] Figure 2 This is a schematic diagram of the working state of the present invention after being rotated 4°;

[0025] Figure 3 for Figure 1 A magnified view of the J part;

[0026] Figure 4 for Figure 1 A magnified view of part I;

[0027] Figure 5 It is a schematic diagram of the original Assel roll profile;

[0028] Figure 6 It is a schematic diagram of the structure after the knurling is removed from the inlet cone area according to the present invention;

[0029] Figure 7 It is a schematic diagram of a structure in which the inlet cone area is knurled according to the present invention;

[0030] Figure 8 A physical picture of the steel pipe produced by the present invention;

[0031] Fig. 9 This is a physical picture of the steel pipe produced by the original Assel rolling mill.

[0032] The symbols in the figure are explained as follows:

[0033] Entrance cone area L1, first entrance cone area L11, second entrance cone area L12, rolling area L3, exit fillet area L4, exit cone area L5, first circular arc 1, second circular arc 2. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] See also Figure 1 , Figure 3 , Figure 4 , Figure 6 , Figure 7 The present invention provides a roller profile for reducing the internal thread of a steel pipe rolled by an Assel unit. The length of the roller is 470 mm, the outer diameter is 500 mm, the diameter of the axial hole is 240 mm, and the chemical composition (wt%) of the roller profile is C: 1.65-1.95, Si: 0.4-0.7, Mn: 0.95-1.05, P, S≤0.03, Cr: 1.3-1.8, Ni: 0.8-1.2, Mo: 0.4-0.6, Nb: trace amount, and the rest is Fe and unavoidable impurities. From the inlet side to the outlet side of the roller, an inlet cone area L1, a shoulder area L2, a rolling area L3, an outlet fillet area L4, and an outlet cone area L5 are sequentially arranged, wherein the inlet cone area L1 is composed of a first inlet cone area L11 and a second inlet cone area L12, wherein the first inlet cone area L11 is located between the second inlet cone area L12 and the inlet end of the roller. In this embodiment, the inlet end of the roller is Figure 1 left end.

[0036] In this embodiment, in order to control the diameter reduction of the incoming steel pipe, the length of the first inlet cone zone L11 along the roller axis and the length of the second inlet cone zone L12 along the roller axis are 7:10, and the inlet cone angle α1 of the first inlet cone zone L11 and the inlet cone angle α2 of the second inlet cone zone L12 differ by 1°. In this embodiment, the axis of the roller is the straight line AB, the length of the first inlet cone zone L11 along the roller axis is set to 70 mm, and the angle of its inlet cone angle α1 is set to 6°, and the inlet cone angle α1 is the angle between the straight line CD and the straight line EF, wherein the straight line CD is the rolling center line of the roller, wherein the angle between the straight line CD and the straight line AB is 4°, that is, the angle between the rolling center line of the roller and the axis of the roller is 4°, wherein the straight line EF is the surface of the first inlet cone zone L11. The length of the second entrance cone zone L12 along the axis of the roller is set to 100 mm, and the entrance cone angle α2 is set to 7°. In this embodiment, the entrance cone angle α2 is the angle between the straight line CD and the straight line FG, where the straight line FG is the surface of the second entrance cone zone L12.

[0037] In this embodiment, a first fillet area is further provided between the first inlet cone area L11 and the inlet end of the roller, and the fillet radius of the first fillet area is 100 mm.

[0038] In this embodiment, in order to fully roll the inner and outer surfaces and wall thickness of the steel pipe, the rolling zone L3 is connected to the entrance cone zone L1 through the shoulder zone L2, and the length of the rolling zone L3 is 4:5 to the length of the second entrance cone zone L12. In this embodiment, the length of the rolling zone L3 along the roller axis is set to 80 mm.

[0039] In this embodiment, in order to control the amount of wall reduction of the steel pipe and play a role in slowly reducing the wall thickness of the steel pipe, the length of the shoulder area L2 along the axis of the roller and the height of the shoulder area L2 along the radial direction of the roller axis are 848:403. In this embodiment, the length of the shoulder area L2 along the axis of the roller is set to 8.48mm, and its height along the radial direction of the roller is set to 4.03mm. The shoulder area L2 is composed of a first arc 1 and a second arc 2, wherein the first arc 1 is tangent to the second arc 2 in the opposite direction (roughly S-shaped), the first arc 1 is connected to the inlet cone area L1, and its radius is 3.3mm, and the second arc 2 is connected to the rolling area L3, and its radius is 8mm.

[0040] In this embodiment, in order to increase the amount of expansion in the steel pipe so that the core rod can be easily pulled out of the steel pipe without causing a rod wrapping accident, the length of the outlet cone zone L5 along the roller axis is set to 155 mm, and the outlet cone angle α3 of the outlet cone zone L5 is 4° different from the inlet cone angle α1 of the first inlet cone zone L11. In this embodiment, the outlet cone angle α3 is set to 2°, wherein the outlet cone angle α3 is the angle between the straight line CD and the straight line HK, wherein the straight line HK is the surface of the outlet cone zone L5.

[0041] In this embodiment, the outlet cone area L5 is connected to the rolling area L3 through the outlet fillet area L4, and the length of the outlet fillet area L4 along the axis of the roller is 20.9 mm.

[0042] In this embodiment, a second fillet area is provided between the outlet cone area L5 and the outlet end of the roller, wherein the outlet end of the roller is Figure 1 At the right end, the radius of the second fillet area is 30 mm.

[0043] In this embodiment, knurling is further provided at the inlet cone area L1 to increase the friction between the roller and the steel pipe. The spacing of the knurling is 1.5 mm and the depth is 0.3 mm.

[0044] In this embodiment, the non-concentricity of the roller shaft hole to the roller surface circle with a diameter of 500 mm shall not be greater than 0.05 mm. The non-perpendicularity of the roller shaft hole side wall to its center line shall not be greater than 0.05 mm.

[0045] In this embodiment, the depth of the composite layer of the roller is not less than 30 mm, the hardness of the finished product is HB: 370-420, the hardness difference is HB≤20, and the hardened layer is ≥30 mm.

[0046] The present invention firstly achieves the effect of uniform steel pipe wall thickness by slowly reducing the outer diameter of the steel pipe (air rolling), thereby solving the technical problem that the inner surface of the produced steel pipe presents spiral bumps, which affects the appearance of the steel pipe and seriously affects the use by users.

[0047] The present invention is based on the law of least resistance: when metal undergoes plastic deformation under the action of external force, each particle inside it always flows in the direction of least resistance.

[0048] See also Figure 2When the present invention is installed and used, it is necessary to rotate the present invention by 4° and install it on the Assel rolling mill. At this time, the angle between the axis of the roller and the rolling center line of the roller is 0°, that is, the angle between the straight line AB and the straight line CD is 0°, and the angle between the straight line CD and the straight line EF is 2°, that is, the angle of the inlet cone angle α1 is 2°, and the angle between the straight line CD and the straight line FG is 3°, that is, the angle of the inlet cone angle α2 is 3°, and the angle between the straight line CD and the straight line HK is 6°, that is, the angle of the outlet cone angle α3 is 6°.

[0049] The Assel roller of the present invention and the original roller profile based on the prior art were used to test roll 27SiMn steel with a design specification of 159*20. The rolling process was the same. The thread depth data (unit: mm) of the inner wall surface of the produced steel pipes were compared as shown in the following table:

[0050]

[0051] The above comparison table is obtained by the applicant through multiple experiments that the thread depth of the inner wall surface of the steel pipe produced by the roller type of the present invention is smaller than that of the steel pipe produced by the original Assel roller type. It also further illustrates that the steel pipe produced by the present invention is more beautiful than the steel pipe produced by the original Assel roller type by resetting the length of the entrance cone area and the angle of the entrance cone angle, the length of the rolling area, the length and height of the shoulder area, while not affecting the user's use (such as difficulty in cold drawing, knife hitting during machining, etc.). Moreover, when visually inspecting the inner surface of the steel pipe with a flashlight, the inner surface of the pipe wall produced by the Assel roller type of the prior art has a very obvious and serious inner spiral depression phenomenon. For details, see Fig. 9 The inner surface of the tube produced by the Assel roller type according to the present invention is very smooth, with only slight spiral marks. Figure 8 .

[0052] See also Figure 5 , which is the original Assel roll size and structure.

[0053] It should be noted that, in this article, terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0054] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A roller profile for reducing the internal thread of a steel pipe rolled by an Assel unit, wherein an inlet cone area, a shoulder area, and a rolling area are sequentially arranged from the inlet side to the outlet side of the roller, and the characteristics are: The inlet cone area consists of a first inlet cone area and a second inlet cone area, wherein the first inlet cone area is located between the second inlet cone area and the inlet end of the roller, wherein the length of the first inlet cone area along the roller axis and the length of the second inlet cone area along the roller axis are in a ratio of 7:10, and the inlet cone angle α1 of the first inlet cone area and the inlet cone angle α2 of the second inlet cone area differ by 1°; The rolling zone is connected to the second inlet cone zone through the shoulder zone, and the ratio of the length of the rolling zone along the roller axis to the length of the second inlet cone zone along the roller axis is 4:

5. The inlet cone angle α1 of the first inlet cone area is the angle between the rolling center line of the roll and the surface of the first inlet cone area. The inlet cone angle α2 of the second inlet cone area is the angle between the rolling center line of the roll and the surface of the second inlet cone area; The angle between the rolling center line of the roller and the axis of the roller is 4°. The length of the first inlet cone area along the roller axis is 70 mm; the length of the second inlet cone area along the roller axis is 100 mm; The inlet cone angle α1 of the first inlet cone region is 6°, and the inlet cone angle α2 of the second inlet cone region is 7°.

2. The roll profile according to claim 1, characterized in that: The length of the rolling zone along the roller axis is 80 mm.

3. The roll profile according to claim 1, characterized in that: The ratio of the length of the shoulder area along the axis of the roller to the length of the second entrance cone area along the axis of the roller is 8.48:100, and its radial height along the roller is 4.03mm; the shoulder area is composed of a first arc connected to the second entrance cone area and a second arc connected to the rolling area, wherein the first arc is tangent to the second arc in the opposite direction, the radius of the first arc is 3.3mm, and the radius of the second arc is 8mm.

4. The roll profile according to claim 1, characterized in that: The inlet cone area is provided with knurling, the pitch of the knurling is 1.5 mm, and the depth is 0.3 mm.

5. The roll profile according to claim 1, characterized in that: The roller further comprises an exit cone zone, the length of which along the axis of the roller is 155 mm, and an exit cone angle α3 thereof differs from the entry cone angle α1 by 4°.

6. The roll profile according to claim 5, characterized in that: The outlet cone angle α3 is the angle between the rolling center line of the roller and the surface of the outlet cone area, and the outlet cone angle α3 is 2°.

7. The roll profile according to claim 5, characterized in that: An outlet fillet area is arranged between the outlet cone area and the rolling area, and the length of the outlet fillet area along the roller axis is 20.9 mm.

8. The roll profile according to claim 5, characterized in that: A first fillet area is provided between the first inlet cone area and the inlet end of the roller, A second fillet area is provided between the outlet cone area and the outlet end of the roller.

9. The roll profile according to claim 8, characterized in that: The fillet radius of the first fillet area is 100 mm, and the fillet radius of the second fillet area is 30 mm.

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