A method for four-cutting Φ12mm specification screw thread steel

Abstract

The application discloses a four-cutting hole type rolling method for Φ12mm specification threaded steel, and belongs to the technical field of steel rolling cutting, and solves the problem of frequent exit failure of finished product racks in the four-cutting rolling process in the current threaded steel production. The application comprises the following steps: aligning the exit guide of each rack of each production unit, adjusting the guide opening degree and matching the rolling piece size, rolling the threaded steel into a Φ71mm round hole type in a 1#-6# rough rolling unit, rolling the threaded steel into a 7#-11# intermediate rolling unit and a 13#-18# finishing rolling unit in sequence, cutting the threaded steel by a 16# rolling mill, shaping the threaded steel by a 17# and a 18# rolling mill, and outputting the finished product. The application changes the hole type design in the intermediate rolling unit, the rolling mill cutting hole type design and the flat material type height control, so that the bending deformation of the head of the rolling piece is basically eliminated, and the bending exit failure caused by the head deflection is avoided.

Description

Technical Field

[0001] This invention belongs to the field of steel rolling technology, specifically relating to a method for rolling Φ12mm rebar using a four-section die. Background Technology

[0002] Rebar manufacturers commonly use four-slit rolling to produce smaller sizes to significantly increase output and reduce production costs. However, the four-slit rolling process requires high precision in material shape control, and adjusting the material shape of each stand is difficult. The most common fault is that the finished product stands are punched out of the outlet, which seriously affects the further improvement of four-slit output and the progress of indicators.

[0003] Currently in production, the cross-sectional area of ​​the workpieces rolled on the No. 12 mill of the intermediate rolling mill is elliptical. After passing through the No. 2 flying shear head, the ends of the workpieces are flush. During the deformation process of the flat rolls on the No. 13 mill, the reduction in the middle part of the workpiece is greater than that on the sides, and the extension in the middle part of the workpiece is greater than that on the sides. In addition, the workpieces on the first four stands of the finishing mill (No. 13-No. 16 mills) are wider. The deformation mechanisms of the two center lines and the two side lines are different in the pre-cutting and cutting passes. The metal in the two center lines mainly extends in the length direction due to the constraints of the pre-cutting and cutting passes, while the metal in the two side lines extends in the same direction. The flow also extends towards the edge of the pass, meaning the middle part of the rolled piece extends further than the sides. All the accumulated deformation causes a severe bulging shape at the head of the rolled piece. After the bulging head rolled piece is separated by the slitting stand, each line has an asymmetrical slanted head shape. After the rolled piece is deformed by the No. 17 rolling mill, the head slant becomes more obvious. When the slanted head rolled piece enters the pass of the No. 18 rolling mill, the pointed part contacts the roll first. After the pointed part is deformed by rolling, a bending defect will inevitably occur. Once the head is severely bent, it is very easy to touch the tip of the nose cone of the exit guide, causing bending and ultimately causing the finished product stand to fail at the exit. Summary of the Invention

[0004] This invention provides a method for rolling Φ12mm rebar using a four-slit die to solve the problem of frequent failures at the exit of the finished product stand during the four-slit rolling process in current rebar production.

[0005] The technical solution of this invention is: a method for rolling Φ12mm threaded steel bars using a four-slit die, comprising the following steps:

[0006] A. Align the inlet and outlet guides of each stand in each production unit, adjust the guide opening and match the dimensions of the rolled piece;

[0007] B. The rebar is rolled into a Φ71mm round die on the No. 1-6 roughing mills and then enters the intermediate rolling mill unit along with the production line;

[0008] C. Rebar is rolled sequentially in the intermediate rolling mills 7#-11#. Among them, the 7# rolling mill uses an elliptical pass, the 8# rolling mill uses a round pass, the 9# rolling mill uses a flat roll, the 10# rolling mill uses a box pass, and the 11# rolling mill uses a flat roll. After the intermediate rolling mills are completed, the rebar enters the finishing mill with the production line.

[0009] D. Rebar is rolled sequentially in the 13#-18# finishing mills, with the 13# mill using flat rolls, the 14# mill using box-shaped passes, the 15# mill using pre-cut passes, the 16# mill using slit passes, and the 17# and 18# mills using shaping mills to output the finished product.

[0010] As a further improvement of the present invention, in step C, the flat rolled piece (26mm×61mm) from the No. 11 rolling mill passes horizontally through the No. 2 flying shear. After the No. 2 flying shear head is cut, its head cross section is rectangular and the head end face is flush. After passing through the No. 2 flying shear head, it enters the finishing mill for rolling.

[0011] As a further improvement of the present invention, in step D, the actual height of the rolled piece after passing through the No. 13 rolling mill is no more than 17.5 mm.

[0012] As a further improvement of the present invention, in step E, the gap between the cutting blades of the 16# mill pass is 0.84mm. When the mill roll is grooved in this stand, a roll ring with a height of 1mm needs to be left on both sides of the pass to prevent the cutting blades from touching and breaking off during the operation of the mill roll.

[0013] As a further improvement of the present invention, a looper is installed between the stands of the finishing mill to achieve tension-free rolling, and the number of looper channels is consistent with the number of rolled pieces.

[0014] The beneficial effects of this invention are as follows: By changing the pass design in the intermediate rolling mill, the pass of the No. 9 rolling mill is changed from elliptical to flat roll, the pass of the No. 10 rolling mill is changed from circular to box-shaped, and the pass of the No. 11 rolling mill is changed from elliptical to flat roll. This makes the flat rolled piece from the No. 11 rolling mill flush at the end after being sheared by the No. 2 flying shear head. The cross-sectional area of ​​the rolled piece is close to that of a rectangle. When the rolled piece is deformed during rolling in the finishing mill, the reduction in the width direction of the rolled piece is consistent, and its extension is basically consistent. Therefore, there is no obvious bulging or deformation at the head of the rolled piece. At the same time, the height of the rolled piece is controlled by the No. 13 rolling mill. The height is changed from no restriction to an actual height of no more than 17.5mm. This makes the reduction of the rebar in the pre-cutting pass of the No. 15 rolling mill and the cutting pass of the No. 16 rolling mill smaller. After the four rolled pieces are separated, the heads of the four rolled pieces are relatively standardized. When the finished stand bites in, the upper and lower grooves contact the head of the rolled piece almost simultaneously. The bending deformation of the rolled piece head is basically eliminated, and the bending exit failure caused by head skew is eliminated. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the rolling mill pass type of the present invention in rolling mills #8-#11;

[0016] Figure 2 This is a schematic diagram of the pass patterns of the finishing mill units 13#-18# of the present invention;

[0017] Figure 3 This is a schematic diagram of the cross-section and head shape of the rolled piece for each stand corresponding to the original four-slit rolling mill system for Φ12mm threaded steel.

[0018] Figure 4 This is a schematic diagram of the cross-section and head shape of the rolled piece corresponding to the pass system of the present invention;

[0019] Figure 5 This is a diagram of the cutting pass of the No. 16 rolling mill in an embodiment of the present invention. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to specific embodiments.

[0021] Example 1: Application of the present invention in rolling Φ12mm rebar using a four-slit die:

[0022] A method for rolling Φ12mm rebar using a four-section pass system is disclosed. The roughing mill operates in six passes using an elliptical-circular shared pass system. The output piece from mill #6 is a Φ71mm circle. The intermediate mill operates in five passes (mill #12 passes through empty using a guide groove). Mill #7 uses an elliptical pass; mill #8 uses a circular pass, producing a Φ55mm circle; mill #9 uses flat roll rolling with a roll gap of 29mm; mill #10 uses a box-shaped pass with a roll gap of 22mm, producing a 60×30mm rectangular piece; and mill #11 uses flat roll rolling with a roll gap of 26mm, producing a flat piece.

[0023] Flat rolled pieces are transported along the production line, entering the No. 12 rolling mill from the intermediate rolling mill group, and then entering the finishing rolling mill group after the empty rolls of the No. 12 rolling mill.

[0024] The finishing mill has six passes. Mill #13 is a flat roll mill; the roll gap is set to 17.5mm because the actual workpiece height is 17.3mm. Mill #14 is a box-type pass mill with a roll gap of 8mm, producing a rectangular workpiece. Mill #15 is a pre-slit pass mill with a centerline height of 16.52mm, an edgeline height of 16mm, and a roll gap of 2.6mm, producing a four-line parallel workpiece. Mill #16 is a split pass mill with a centerline height of 13.8mm, an edgeline height of 14.3mm, and a straight section at the bottom of the centerline pass. The splitting blade clearance is 0.84mm. Mill #17 is an elliptical pass mill with a roll gap of 2.7mm, producing an elliptical workpiece. Mill #18 is a finished product pass mill.

[0025] By optimizing the pass design of the intermediate rolling mills (7#-11#) and finishing rolling mills (13#-18#), and analyzing the deformation mechanism, the uneven deformation of the workpiece head at the finishing mills (13#-18#) was reduced. This ensured that the workpiece head was relatively flat before cutting and that the heads of each line were standardized after cutting, thus improving the head shape. As a result, the problem of bent head and exit nose cone did not occur when the finished product stand bit into the workpiece, effectively solving the exit failure of the four-cut rolling process of this specification.

[0026] The process parameters are designed as shown in the table below:

[0027]

[0028] The flat rolled pieces on the No. 11 rolling mill are horizontally cut off by the No. 2 flying shear. After the head is cut off, the head of the rolled piece is flat. Each set of rolling grooves on the No. 17 and No. 18 rolling mills has 4 equally spaced rolling grooves (the spacing is generally 135mm) to roll the 4-line rolled pieces separated by the No. 16 rolling mill at the same time. The No. 17 rolling mill is equipped with a torsion guide at the exit. The 4-line rolled pieces are torsioned 90° before entering the No. 18 rolling mill to be rolled into finished products.

[0029] Each stand's roll pattern design (except for flat rolls) is combined with the configuration of inlet and outlet guides and the length of the roll body to design the roll pattern matching diagram. Based on the roll matching diagram, the rolls are grooved and assembled before being put into use on the production line.

[0030] In order to stabilize the control of rolled piece dimensions and reduce the changes in rolled piece dimensions of each stand caused by wear of the rolling groove during the production process, high-speed steel rolls are used in the finishing mill stand, the pre-finishing stand, and the pre-cutting stand.

Claims

1. A method of four-way split of a hole-rolling Φ 12 mm gauge threaded steel, characterized by, It comprises the following steps: A. Aligning the entry and exit guides of each rack of each production unit, adjusting the opening degree of the guides and matching the size of the rolled piece; B. The threaded steel is rolled into a Φ71mm round hole in the 1#-6# rough rolling unit and enters the intermediate rolling unit along with the production line; C. The threaded steel is rolled in the 7#-11# intermediate rolling unit in turn, wherein the 7# rolling mill adopts an oval hole, the 8# rolling mill adopts a round hole, the 9# rolling mill adopts a flat roller rolling, the 10# rolling mill adopts a box hole, the 11# rolling mill adopts a flat roller rolling, after the intermediate rolling unit, the threaded steel enters the finishing rolling unit along with the production line; D. The threaded steel is rolled in the 13#-18# finishing rolling unit in turn, wherein the 13# rolling mill adopts a flat roller rolling, the 14# rolling mill adopts a box hole, the 15# rolling mill adopts a pre-cutting hole, the 16# rolling mill adopts a cutting hole, the 17# rolling mill and the 18# rolling mill are shaped, and the output finished product, the actual height of the rolled piece passing through the 13# rolling mill is not greater than 17.5mm, the gap between the cutting blades of the 16# rolling mill hole is 0.84mm, and when the grooves of the rolling mill are engraved, 1mm high roller rings need to be left on both sides of the hole.

2. A method of four split pass Φ 12 mm size threaded steel as claimed in claim 1, wherein: In the step C, the flat rolled piece output by the 11# rolling mill passes through the 2# flying shear horizontally, the head end surface is flush after the head is cut by the 2# flying shear, and then enters the finishing rolling unit for rolling.

3. A method of four-way split of a hole-type rolled Φ 12 mm gauge threaded steel rod as claimed in claim 1 or 2, wherein: A loop is installed between the finishing rolling racks, and the number of loop channels is consistent with the number of rolled pieces.

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