阅读说明：本技术 一种毛管大扩径轧制方法 (Method for rolling large diameter of tubular billet ) 是由 边境 高万峰 于 2019-08-30 设计创作，主要内容包括：本发明属于无缝管生产技术,具体涉及一种毛管大扩径轧制方法,该方法是在菌式穿孔机上将加热好的实心管坯穿孔扩径制成空心的毛管,菌式穿孔机两个轧辊呈辗轧角为α、咬入角为β设置,所述轧辊的出口区辊面角Yc大小为5°≤Yc≤α。该方法在菌式穿孔机上实现了毛管大扩径技术,可使毛管壁厚均匀,大大减少切头切尾长度,提高成材率。同时解决现有的技术毛管尾部经常会产生铁耳子等问题；提高了生产效率。(The invention belongs to the production technology of seamless pipes, and particularly relates to a large-diameter-expanding rolling method of a hollow tubular billet, which is characterized in that a heated solid tubular billet is punched and expanded on a bacterial type puncher to form the hollow tubular billet, two rollers of the bacterial type puncher are arranged with a rolling angle alpha and a biting angle beta, and the roll surface angle Yc of an outlet area of each roller is more than or equal to 5 degrees and less than or equal to Yc and less than or equal to alpha. The method realizes the large diameter expansion technology of the capillary on the bacterial perforating machine, can ensure that the wall thickness of the capillary is uniform, greatly reduces the length of the head and the tail of the cut and improves the yield. Meanwhile, the problems that the tail part of the capillary tube often produces pig iron and the like in the prior art are solved; the production efficiency is improved.)

1. A large-diameter-expanding rolling method of a hollow capillary is characterized in that a heated solid tube blank (1) is punched and expanded on a mushroom-type puncher to form a hollow capillary (4), two rollers (2) of the mushroom-type puncher are arranged with a rolling angle alpha and a biting angle beta, and the method is characterized in that: the roll surface angle Yc of the outlet area of the roll (2) is more than or equal to 5 degrees and less than or equal to alpha.

2. The method for rolling a hollow billet with large diameter expansion according to claim 1, wherein: the expanding ratio delta =1-P (tan (yc) Lc 2)/Bck) + 1);

where P is the selected reduction and Bck is the throat size at the intersection of the entry and exit regions of roll (2).

3. The method for rolling a hollow billet with large diameter expansion according to claim 2, wherein: said P = Dp (9% ~ 15%), said Bck = Dm- (tan (yc) Lc) 2;

wherein Dp is the outer diameter of the tube blank (1), and Dm is the outer diameter of the tube blank (4).

4. The method for rolling a hollow billet with large diameter expansion according to claim 3, wherein: the rolling angle alpha is more than or equal to 10 degrees and less than or equal to 15 degrees, and the bite angle beta is more than or equal to 7 degrees and less than or equal to 12 degrees.

Technical Field

The invention belongs to the production technology of seamless tubes, and particularly relates to a large diameter-expanding rolling method for a tubular billet.

Background

The history of the development of the bacterial (or conical) roll cross-piercing mill (note, hereinafter, abbreviated as "bacterial piercing mill") was also described in "Steel pipe", 5 th Stokes 1999, and "the development of piercing process and reissue of conical roll piercing mill", which were written in "cabbage", 2003, 4 th month 2, and the first application of steefel was published in 1897, and then the bacterial piercing mill was released. Until 1981, mannesmann tube works installed one mushroom punch in place of two steefel punches in front of the original 340 automatic tube mill (note, barrel rolls with fixed guide plates (i.e., roll angle α = 0) cross-roll punches, hereinafter referred to as barrel punches).

The industry is well aware that the bacterial type puncher has larger deformability and is suitable for the punching production of pipe blanks with high alloy and poor plasticity; the structural characteristics of the equipment show that: the rolling angle alpha is large, the feeding angle beta is large, and the adjusting range is large. However, since no mature technology is input in the technical aspect of the process, the specific matching relationship between the rolling angle α and the feeding angle β, the diameter expansion rate δ of the tubular billet, and the perforation extension coefficient μ is not clarified in the industry, and a detailed and specific design method is not provided. Therefore, the research and study of the professionals in practice have been continued, and the following descriptions are also available in the relevant professional books: the maximum diameter expansion rate delta of the two-roll type mushroom-type piercing mill can reach about 40%, but too large diameter expansion rate not only brings difficulty to hole pattern adjustment, but also reduces wall thickness precision (offset wall) and surface quality of the capillary, and tail 'ears' and the like. To obtain a high-quality capillary, the diameter expansion rate is preferably about 10-15%. From the diameter expansion rate delta statistics of the current bacterial piercing mills in several large seamless steel tube factories in China, the diameter expansion rate delta is basically within the range of delta < 30%.

On the current bacterial perforator, the following problems exist in the unit:

1) the range of punched products is narrow, and in order to expand the specification range of the products, a secondary puncher or a roller type rotary expanding machine and the like are required to be adopted, so that the process investment and the high cost are increased;

the Dp is large in size, the heating time is long, the cost is increased, and the production efficiency is reduced.

Therefore, research and development of a process method for expanding the diameter of the capillary tube to improve the diameter expansion rate delta of the bacterial perforator and obtain products with high quality, high efficiency and low cost are urgent technical problems to be solved.

Disclosure of Invention

In order to solve the problems, the invention provides a large-diameter-expanding rolling method for a tubular billet, which improves the diameter expansion rate delta of the tubular billet to more than 30 percent by controlling the roll face angle Yc of the outlet area of a rolling roll in a rolling pass and adjusting the matching relation of a rolling angle alpha and a feeding angle beta, and realizes high-efficiency and low-cost production. The technical scheme adopted by the invention is as follows:

a large diameter-expanding rolling method for hollow tubular billet features that a heated solid tubular billet is perforated and expanded by a bacterial perforating machine to obtain hollow tubular billet, two rollers of said bacterial perforating machine are arranged at rolling angle alpha and biting angle beta, and the surface angle Yc of said rollers at outlet area is not less than 5 deg. and not more than Yc and not more than alpha.

The diameter expansion ratio of the mushroom-type piercing mill δ =1-P (tan (yc) Lc 2)/Bck) + 1;

where P is the selected reduction and Bck is the throat size at the intersection of the entry and exit regions of the roll.

The method for rolling the large diameter-expanded hollow billet comprises the following steps of (1) performing large diameter-expanded rolling on the hollow billet, wherein P = Dp (9% -15%), and Bck = Dm- (Tan (Yc) Lc) 2;

wherein Dp is the outer diameter of the tube blank, and Dm is the outer diameter of the tube blank.

According to the method for rolling the large diameter-expanding hollow billet, the rolling angle alpha is more than or equal to 10 degrees and less than or equal to 15 degrees, and the bite angle beta is more than or equal to 7 degrees and less than or equal to 12 degrees.

The invention has the beneficial effects that: the large diameter expanding technology of the capillary is realized on the bacterial perforating machine, the wall thickness of the capillary is uniform, the length of the crop end and the crop end is greatly reduced, and the yield is improved. Meanwhile, the problems that the tail part of the capillary tube often produces pig iron and the like in the prior art are solved; the production efficiency is improved.

Drawings

FIG. 1 is a schematic front view of the present invention;

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

fig. 3 is a schematic diagram of a variant of the present invention.

In the figure: 1 is a tube blank, 2 is a roller, 3 is a top, 4 is a capillary and 5 is a guide plate.

Detailed Description

Taking the production of the ACCU-ROLL skew tube mill group seamless steel tube as an example, the hot rolling production process generally comprises the following steps:

step 1: heating the solid pipe blank to a temperature suitable for deformation by a heating furnace;

step 2: punching the heated solid tube blank by a cross rolling puncher to prepare a hollow tubular billet;

and step 3: performing extension rolling on the hollow billet by an ACCU-ROLL skew rolling mill to reduce the wall thickness of the hollow billet;

and 4, step 4: and (5) obtaining the steel pipe with the required external diameter specification through a sizing mill or a tension reducing mill.

And 2, perforating the heated solid tube blank by using a bacterial perforating machine to form the hollow capillary tube.

The invention is further explained below with reference to the drawings.

Deformation tool in mushroom-punch hole: consists of a pair of mushroom-shaped rollers 2 which actively rotate, a top 3 and a pair of guide plates 5. The mushroom-type rolls 2 are generally arranged up and down (or left and right, in the embodiment, the mushroom-type rolls are arranged up and down), and the guide plates 5 are arranged left and right; the axis of the mushroom-type roller and the rolling central line form an included angle in a horizontal plane, which is called a bite angle beta. The mushroom-type roller 2 is used as an external deformation tool and has the function of pulling the tube blank 1 into the hole pattern by means of the friction force of the roller surface to drive the tube blank 1 to rotate and advance; the top 3 is used as an internal deformation tool and is used for carrying out perforation of the tube blank 1 and rolling the inner wall of the hollow billet 4; the guide plate 5 functions to limit the lateral deformation of the capillary 4.

The deformation principle in the pass of the bacterial piercing machine is that the tube blank 1 rotates and advances after contacting the bacterial roller 2: and the tube blank 1 enters a perforation preparation area L1, a perforation area L2 and an expanding rolling area L3 in sequence, and after the processes of perforation, expanding and wall-equalizing rolling are finished in an area L2 and an area L3, the tube blank continues to enter a tubular billet rounding area L4 for rounding to become the required tubular billet. Through the perforation process, the fungus-type perforating machine finishes the perforation of the solid pipe blank with the diameter Dp into the hollow capillary pipe with the diameter Dm and the wall thickness Sm.

There are several important parameters among the deformation parameters of the mushroom-type piercer: (1) a rolling angle alpha, (2) a biting angle beta, and (3) a diameter expansion rate delta of the capillary, delta = (Dm-Dp)/Dp multiplied by 100%; (4) the perforation extension coefficient μ, [ mu ]/[ Dp ]. Dp/(4. (Dm-Sm).

The roll surface angle Yc of the roll outlet area is in a value range, and is derived as follows:

1) according to the most outstanding advantages of the mushroom roll: the roll 2 is characterized in that the sections i1, i2. of the roll surface perpendicular to the axis of the roll 2 from the inlet zone to the outlet zone are increased, the linear speeds Vi1 and Vi2 are increased, and the component speeds Vzi1 and Vzi2 in the direction of the rolling line (Vzi = Vi Sin beta) are also increased, so that the auxiliary force effect is realized on the extension of the metal from the stress angle, and the deformation extension of the metal and the rolling process are facilitated.

At the throat Bck at the intersection of the entrance and exit zones of roll 2, the rolling direction speed is Vzck, Vzck = Vck + Sin β = (Dgck + Ng/60) × Sin β;

at the outlet of the capillary 4, a rolling direction speed Vmz, Vmz = Vm × Sin β = ((Dgck +2 × Lc × Tan (α -Yc)) × pi × Ng/60) × Sin β;

the rolling linear speed increment of the roller is Vzp, Vzp = (Vmz-Vzck)/Hp/2 under the condition of corresponding metal half-pitch;

in the formula, the difference is: Vmz-Vzck = (2 × Lc × Tan (α -Yc) × Pi/60) × Sin β pi

Ng-roll 2 rotational rpm;

hp-analysis in average Pitch of Metal (see 2)

Dgck-diameter of roll at throat

2) The method comprises the following steps that metal in a pass is spirally advanced (note that the pitch of each section is different) under the driving of a roller, meanwhile, the metal per se deforms and flows, and only the metal extension mu c, mu c = ((Dck-Sck) × Sck)/((Dm-Sm) × Sm) in an outlet area in the rolling line direction is analyzed;

in the formula: bck, the outside diameter of the pipe is Dck, Dck = ((1/2 Bck) × 2 × pi +4 (Lck/2-Bck/2))/pi,

the completion of the outlet area muc is that the outlet area spirally advances, namely, the metal is rolled once every half pitch, and certain extension muci occurs to the metal every time until the outlet area is rolled, so that the extension muc of the outlet area is realized.

The metal i cross-sectional pitch Hi = Di × pi Tan (β) of the outlet zone; then: screw Hck = Dck × pi (β) at the orifice throat, pitch at the outlet of the capillary: hm = Dm ═ Tan (β);

the average pitch Hp = (Hck + Hm)/2 was obtained as follows: hp = ((Dck + Dm) × pi × Tan (β))/2.

Then, averagely finishing the mu cp per half pitch, wherein the mu cp = mu c/(Hp/2);

3) assuming that the average metal extension μ cp at the half pitch and the speed increment Vzp in the rolling line direction of the corresponding roll section are equal, namely: mu cp = Vzp (note, in practice, Vzp is preferably not less than mu cp, and the metal is preferably pulled);

therefore, the formula μ cp = Vzp is converted into: tan (α -Yc) = (((Dck-Sck) × Sck)/((Dm-Sm) × Sm))/((2 × Lc × Tan (α -Yc) × pi Ng/60) × Sin β)

The parameters of the above formula can be selected or calculated in a relative relationship.

The calculation process is illustrated below by way of example:

dck =282.23, Sck =109, Dm =440, Sm =16, Lc =740, Ng =100, β =8 °, α =15 °, the calculation result Tan (α -Yc) =0.0026, and (α -Yc) ≈ 0 °. Further examples are Dck =318.5, Sck =127, Dm =440, Sm =16, Lc =540, Ng =100, β =8 °, α =12.5 °, the calculation result is: tan (α -Yc) =0.00455, (α -Yc) ≈ 0 °.

It is thus known that the roll surface angle Yc in the outlet region can be at most the rolling angle α. Namely, as long as Yc is less than or equal to alpha, the rolling line direction of the tube blank 2 has the effect of the rolling surface tension of the rolled tube, which is beneficial to metal deformation in the rolling line direction, so the roll surface angle Yc in the outlet area has the value of Yc =5 degrees-alpha.

Due to the complexity of metal deformation, the above derivation indicates to some extent: the roll surface angle Yc of the outlet area takes the value, and as long as the roll surface angle Yc is less than or equal to the rolling angle alpha, the metal extension in the rolling line direction is assisted by the roll surface tension, which is beneficial to the metal deformation extension (note, it is pointed out that the barrel-shaped roll Vzi of the barrel-shaped puncher decreases progressively, and the roll surface plays a role in blocking the metal extension from the stress angle, thus being not beneficial to the metal deformation extension and the smooth process rolling).

In practice, the rolling load, the ejector rod pressure, the number of times of rolling the wall thickness of the hollow billet, the consumption of tools and the like are comprehensively considered: specifically, the requirements of the outlet roll surface length Lc, the outlet roll surface angle Yc, the roll diameter Dz, the roll rotating speed Ng, the feeding angle beta, the rolling angle alpha, the equipment structure and the like are comprehensively matched.

Next, see the relationship between Dp, Dm and pass:

δ = (Dm-Dp)/Dp 100% [ formula 1 ];

pore throats Bck, Bck = Dp (1-P), wherein the selected reduction P = Dp (9% -15%); so pore throat Bck = Dm- (tan (yc) Lc) × 2;

substituting delta formula 1 and simplifying, then obtain: δ =1-P (K/Bck + 1) 100% [ formula 2 ], where K = tan (yc) Lc 2;

substituting into formula 2 for simplification, δ =1-P (tan (yc) Lc 2)/Bck) + 1) [ formula 3 ],

analyzed with equation 3: when the exit roll face angle Yc and the exit roll face length Lc of the selected roll are selected, the exit area expansion K is determined (note, calculated as K = tan (Yc) Lc × 2), where δ is determined by Bck: bck, the smaller the delta value, and vice versa. In view of the relationship of the blanks Dp and Bck, the smaller Dp, the larger delta value, and vice versa.

The large diameter expanding technology of the capillary is not suitable for the ultra-thick pipe with Dm/Sm < 15.

Example 1

The current fungus formula piercing mill of this factory, its pass parameter is: the roll angle alpha =12.5 degrees, the feed angle beta = 7-11 degrees, the inlet area roll surface angle Yr =2.5 degrees, the outlet area roll surface angle Yc =3 degrees, and the roll length Lz =1000 mm; the billet Dp =350mm, the capillary Dm Sm =440 mm 20mm, and the diameter expansion rate δ = 25.7%.

The diameter expansion method according to the present invention described above: the roll length was 1000mm (unchanged), Yr =2.5 ° (unchanged), the capillary Dm was Sm =440 mm 20mm (unchanged), the alternative take-off region roll face angle Yc =6.2 °, and the stock Dp =310mm, δ = 42%.

The production result is as follows: smooth rolling, good quality of the hollow billet, at least 20-30 minutes reduction of heating time and more than 11% improvement of production rhythm.

Example 2

The factory also has a mushroom-type perforator, a rolling angle alpha =15 degrees, a feeding angle beta = 8-12 degrees, a roller length Lz =700mm, a roller surface inlet angle YR =2.5 degrees, and an outlet angle Yc =3 degrees; stock Dp =210mm, capillary Dm Sm =240 mm 12mm, δ = 14.3%.

The diameter expansion method according to the present invention described above: the blank Dm Sm =240 mm 12mm (unchanged), the roll length Lz =700 (unchanged), the alternative Yc =7 °, the blank Dp =150mm, and δ = 60%.

The production result is as follows: smooth production, good quality of the capillary, saving the heating time by at least 30 minutes, and improving the production rhythm by more than 25 percent.