A two-step method for producing flat steel wire

Abstract

The present invention relates to the technical field of steel cords, and in particular to a method for producing flat steel wires by a two-step method, the method comprising the following steps: a rough drawing process, an intermediate heat treatment process, an intermediate drawing process, a heat treatment electroplating process, a water tank process, and a two-step rolling process. The present invention adopts a two-step method to roll round steel wires into flat steel wires, and the compression rates of the two-step rolling processes are 15% and 16% respectively. The obtained flat steel wires have a breaking force greater than 300N and a two-way torsion greater than 50 times. By replacing one large deformation process with two small deformation processes, the deformation process of the steel wire is gentler, effectively alleviating the damage to the steel wire during the rolling process, reducing microcracks on the surface of the flat steel wire, significantly improving the breaking force and two-way torsion of the flat steel wire, and reducing the probability of the flat steel wire being broken during the stranding process.

Description

Technical Field

[0001] The invention relates to the technical field of steel cords, and in particular to a two-step method for producing flat steel wires. Background Art

[0002] Steel cord is composed of two or more steel wires, or a structure formed by a combination of strands or a combination of strands and wires. Steel cord is widely used in radial tires as a skeleton material. It has developed with the development of radial tires. As people's requirements for tire strength increase, the requirements for steel cord are also higher. Flat steel wire, as a stranding material for steel cord, has certain defects in performance strength.

[0003] The main production methods of flat steel wire are: flat roll rolling or rolling with a certain hole type roll; die drawing is to longitudinally shear the wide plate after hot rolling or cold rolling. Since the flat steel wire produced by flattening rolling has excellent quality and low cost, it has wide application and research value. CN109082510B discloses a preparation process for nearly round flat steel wire suitable for valve springs. The steel wire is first made into round steel wire, and then two rolls are used to roll the round steel wire into flat steel wire. The preparation method of flat steel wire used in common steel cord is similar to it. This rolling method causes great wear on the flat steel wire, and micro cracks appear in the flat steel wire, which makes the flat steel wire easy to break in the stranding process, affecting production efficiency. Summary of the invention

[0004] In order to solve the problem that flat steel wires prepared by conventional methods are prone to wire breakage during the process of being twisted into steel cords, the present invention provides a two-step method for producing flat steel wires. The method for producing flat steel wires can effectively alleviate the damage to the surface of the steel wires during the rolling deformation process, while reducing microcracks on the steel wires after rolling deformation, producing flat steel wires with strong breaking force and large bidirectional torsion, and reducing the phenomenon of wire breakage during the twisting process of the flat steel wires.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] A two-step method for producing flat steel wire according to the present invention comprises the following steps:

[0007] A. Rough drawing process: After the wire rod is pickled and surface boronized, it enters the rough drawing equipment. The rough drawing process draws the wire rod to the corresponding smooth steel wire specifications;

[0008] B. Intermediate heat treatment process: put the smooth steel wire into the heat treatment furnace for water bath quenching;

[0009] C. Middle drawing process: the steel wire which has been heat treated in the middle is further drawn to reduce the diameter of the steel wire;

[0010] D. Heat treatment and electroplating process: The steel wire after intermediate drawing is heat treated, and then copper and zinc are electroplated on the surface of the steel wire respectively, and finally a brass alloy is formed on the surface of the steel wire through thermal diffusion;

[0011] E. Water tank process: Use a water tank wire drawing machine to further draw the electroplated steel wire in the lubricant in the water tank to draw the steel wire into a round steel wire of a specified size;

[0012] F. Two-step rolling process: The round steel wire is rolled twice, with the compression rate of the first rolling being 15% and the compression rate of the second rolling being 16%, to obtain the finished flat steel wire.

[0013] Furthermore, the heat treatment is to heat the steel wire to 900-1100°C.

[0014] Furthermore, the diameter of the round steel wire obtained in step E is 0.38±0.01mm, the first rolling is to roll the round steel wire with a diameter of 0.38±0.01mm into a flat steel wire with a long side of 0.39±0.01mm and a short side of 0.35±0.01mm, and the second rolling is to further roll the steel wire after the first rolling into a finished flat steel wire with a long side of 0.41±0.01mm and a short side of 0.32±0.01mm.

[0015] Furthermore, the device used in the two-step rolling process includes a base, a roll frame is provided on the base, the roll frame includes a first roll frame and a second roll frame arranged in parallel with each other, the first roll frame and the second roll frame are both provided with an adjustment plate, the adjustment plate and the roll frame are both in an inverted "U" shape, the adjustment plate is sleeved on the roll frame, a lower roll and an upper roll are provided in the opening of the roll frame, the lower roll is rotatably connected with the roll frame, a waist-shaped hole is provided at the roll frame corresponding to the upper roll, the upper roll rotation shaft passes through the waist-shaped hole and is rotatably connected with two vertical plates of the adjustment plate, an adjustment mechanism is provided above the horizontal plate of the adjustment plate, and the adjustment mechanism passes through the horizontal plate of the adjustment plate to connect the roll frame. By arranging the steel wire and the roll frame in parallel, when the steel wire is rolled on both sides, the rolling surface of the steel wire is in the same horizontal plane, and the compression rate of the steel wire rolling is adjusted by adjusting the height of the upper roll by the adjustment mechanism.

[0016] Furthermore, the spacing between the lower roller and the upper roller on the first roller stand is 0.35±0.01mm, and the spacing between the lower roller and the upper roller on the second roller stand is 0.32±0.01mm. The compression rates of the steel wire are 15% and 16% respectively. Under the premise of ensuring that the rolled flat steel wire is qualified, the damage to the flat steel wire during the rolling process is checked.

[0017] Furthermore, a connecting plate is provided at the front side of the first roll stand, the connecting plate is in an "L" shape, the connecting plate transverse plate is fixed to the first roll stand, an adjustment hole is provided on the connecting plate vertical plate, a positioning piece is provided on the adjustment hole, the end of the positioning piece is drum-shaped, a wire hole is provided on the plane end of the positioning piece, and the wire hole is located between the lower roll and the upper roll. The positioning piece can adjust the vertical height of the wire to ensure that the wire passes between the lower roll and the upper roll, making the rolling process more stable.

[0018] Furthermore, the maximum distance between the rear end of the first roll stand and the front end of the second roll stand is 10 cm. The distance between the two roll stands is as short as possible to ensure that the two rolling operations are performed on the same surface of the steel wire.

[0019] Through the above technical solution, the beneficial effects of the present invention are:

[0020] 1. The present invention adopts a two-step method to roll round steel wire into flat steel wire, and uses two rolling processes to obtain the flat steel wire. The compression rates of the two rolling processes of the two-step method are 15% and 16% respectively. Two small deformation processes replace one large deformation process, so that the deformation process of the steel wire is gentler, and the damage to the steel wire during the rolling process is effectively alleviated, and the micro cracks on the surface of the flat steel wire are reduced, so that the breaking force and bidirectional torsion of the flat steel wire are significantly improved. The flat steel wire obtained by the two-step rolling method has a breaking force greater than 300N and a bidirectional torsion greater than 50 times. During the stranding process of the flat steel wire, the probability of the flat steel wire breaking during the stranding process is reduced.

[0021] 2. The present invention sets the steel wire and the roller frame in parallel so that the rolling surfaces of the steel wire are on the same horizontal plane when the steel wire is rolled on both sides. The height of the upper roller is adjusted by the adjusting mechanism to adjust the compression rate of the steel wire. The positioning piece can adjust the vertical height of the steel wire to ensure that the steel wire passes between the lower roller and the upper roller, making the rolling process more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a two-step production device for producing flat steel wire according to the present invention. Figure 1 .

[0023] Figure 2 This is a schematic diagram of the structure of a two-step production device for producing flat steel wire according to the present invention. Figure 2 .

[0024] Figure 3 It is a structural schematic diagram of the flat steel wire produced by the present invention.

[0025] The numbers in the accompanying drawings are: 1 is a base, 2 is a first rolling stand, 3 is an adjustment plate, 4 is a connecting plate, 5 is a positioning member, 6 is a second rolling stand, 7 is an adjustment mechanism, 8 is an adjustment hole, 9 is a lower rolling roll, and 10 is an upper rolling roll. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments: The following examples are used to illustrate the present invention, but are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The test methods in the following examples are conventional methods unless otherwise specified.

[0027] A two-step method for producing flat steel wire according to the present invention comprises the following steps:

[0028] A. Rough drawing process: After pickling and surface boronization, the wire rod with a nominal diameter of 5.5 mm enters the rough drawing equipment. The rough drawing process draws the wire rod to the corresponding smooth surface steel wire specification, with a nominal diameter of 2.0-3.5 mm;

[0029] B. Intermediate heat treatment process: The smooth steel wire is put into the heat treatment furnace for water bath quenching. In this process, the steel wire is first heated to 900-1100℃ to austenitize the steel wire, and then the austenite is converted into pearlite in a water bath to prepare for the next step of drawing;

[0030] C. Middle drawing process: The steel wire which has been heat treated in the middle is further drawn to reduce the diameter of the steel wire, and the nominal diameter of the obtained steel wire is 1.0-2.5mm;

[0031] D. Heat treatment and electroplating process: Since the steel wire has been drawn, it needs to be heat treated again. The steel wire is heated to 900-1100℃ to austenitize the steel wire, and then the austenite is converted into pearlite in a water bath. Then copper and zinc are electroplated on the surface of the steel wire respectively, and finally a brass alloy is formed on the surface of the steel wire through thermal diffusion;

[0032] E. Water tank process: using a water tank wire drawing machine, the electroplated steel wire is further drawn in the lubricant in the water tank to draw the steel wire into a round steel wire of a specified size; in this embodiment, the steel wire is drawn into a diameter of 0.38±0.01 mm;

[0033] F. Two-step rolling process: The round steel wire is rolled twice, the compression rate of the first rolling is 15%, and the compression rate of the second rolling is 16%. In this embodiment, the diameter of 0.38±0.01mm is first rolled into a flat steel wire with a long side of 0.39±0.01mm and a short side of 0.35±0.01mm, and then the steel wire is further rolled into a finished flat steel wire with a long side of 0.41±0.01mm and a short side of 0.32±0.01mm.

[0034] In this embodiment, the rolling process uses two rolling steps to obtain the flat steel wire. The compression rates of the two rolling steps of the two-step method are 15% and 16% respectively. Two small deformation processes replace one large deformation process, so that the deformation process of the steel wire is gentler, and the damage to the steel wire during the rolling deformation process is reduced. The flat steel wire obtained by the two-step rolling method has a breaking force greater than 300N and a bidirectional torsion greater than 50 times. The probability of wire breakage during the stranding process of this type of flat steel wire is low, which meets production requirements.

[0035] The properties of the flat steel wire produced by the method of the present invention before and after rolling were experimentally tested and compared. Table 1 shows the experimental test results.

[0036] Table 1:

[0037]

[0038] The experimental results show that rolling into flat steel wire will inevitably reduce the breaking force and bidirectional torsional performance, but the reduction is small. The performance reduction can be minimized while reducing costs and meeting production expectations.

[0039] Through the present invention, it can be imagined that: flat steel wire can also be obtained by more rolling, and the breaking force and bidirectional torsion of the obtained flat steel wire are higher, but due to the linear relationship, during multiple rolling processes, since the distance the steel wire moves during the rolling process is too long, the steel wire may rotate, resulting in the rolling roller device being unable to ensure that the places where the pressure rollers are deformed are in the same straight line, and unable to ensure that the surfaces of the steel wire rolling rollers are in the same horizontal plane, resulting in unqualified shapes of the rolled products. The present invention reduces the number of rolling times to ensure the qualified rate of the rolled flat steel wire under the premise of satisfying the breaking force of the flat steel wire being greater than 300N and the bidirectional torsion being greater than 50 times.

[0040] like Figure 1 to Figure 3As shown, the device adopted in the two-step rolling process includes a base 1, on which a roll frame is provided, and the roll frame includes a first roll frame 2 and a second roll frame 6 arranged parallel to each other, and the first roll frame 2 and the second roll frame 6 are both provided with an adjusting plate 3, and the adjusting plate 3 and the roll frame are both in an inverted "U" shape, and the adjusting plate 3 is sleeved on the roll frame, and a lower roll 9 and an upper roll 10 are provided in the opening of the roll frame, and the lower roll 9 is rotatably connected to the roll frame, and a waist-shaped hole is opened at the roll frame corresponding to the upper roll 10, and the rotating shaft of the upper roll 10 passes through the waist-shaped hole and is rotatably connected to the two vertical plates of the adjusting plate 3, and an adjusting mechanism 7 is provided above the horizontal plate of the adjusting plate 3, and the adjusting mechanism 7 passes through the horizontal plate of the adjusting plate 3 to connect the roll frame. The round steel wire to be rolled passes horizontally between the two rollers on the roll stand, and the steel wire is parallel to the two roll stands to prevent the steel wire from twisting after passing through the first roll stand 2, resulting in the two rollings not being in the same plane of the steel wire. The height of the adjusting plate 3 can be adjusted by the adjusting mechanism 7, so that the upper roller 10 can be adjusted within the range of the waist-shaped hole to change the gap between the lower roller 9 and the upper roller 10, and the round steel wire can be rolled into a flat steel wire of a specified size. In this embodiment, the adjusting mechanism 7 can be adjusted in height by bolt and gasket adjustment, and the adjusting plate 3 and the roll stand are connected by bolts. The height of the adjusting plate 3 is adjusted by adding a gasket at the gap between the adjusting plate 3 and the roll stand, so as to achieve the purpose of adjusting the gap distance between the lower roller 9 and the upper roller 10.

[0041] The spacing between the lower roller 9 and the upper roller 10 on the first roller stand 2 is 0.35±0.01mm, and the spacing between the lower roller 9 and the upper roller 10 on the second roller stand 6 is 0.32±0.01mm. In this embodiment, the round steel wire of 0.38±0.01mm is rolled, and the round steel wire is first rolled into a flat steel wire with a short side of 0.35±0.01mm, and then rolled into a flat steel wire with a short side of 0.32±0.01mm, and the compression rates are 15% and 16% respectively.

[0042] A connecting plate 4 is provided at the front side of the first roll stand 2. The connecting plate 4 is in an "L" shape. The horizontal plate of the connecting plate 4 is fixed to the first roll stand 2. An adjustment hole is provided on the vertical plate of the connecting plate 4. A positioning member 5 is provided on the adjustment hole. The end of the positioning member 5 is drum-shaped. A wire hole is provided on the plane end of the positioning member 5. The wire hole is located between the lower roll 9 and the upper roll 10. The wire passes through the wire hole on the positioning member 5. By adjusting the height of the positioning member 5, the height of the wire vertical line can be adjusted to ensure that the wire passes between the lower roll 9 and the upper roll 10. In this embodiment, the positioning member 5 is fixed on the connecting plate 4 by a nut. Loosening the fixed nut can adjust the positioning member 5 to move in the adjustment hole on the connecting plate 4.

[0043] The maximum distance between the rear end of the first roll stand 2 and the front end of the second roll stand 6 is 10 cm. To ensure that the two rolling operations are performed on the same surface of the steel wire, the distance between the two roll stands is as short as possible, and the distance used in this embodiment is about 5 cm.

[0044] When in use, the height of the upper roller 10 is adjusted by the adjusting mechanism 7 so that the spacing between the lower roller 9 and the upper roller 10 is the set value, and the height of the positioning member 5 is adjusted so that the horizontal height of the wire hole on the positioning member 5 and the horizontal height between the lower roller 9 and the upper roller 10 are in the same horizontal plane. The steel wire to be rolled passes through the steel wire hole on the positioning member 5, and then passes through the two rollers on the two roller stands in turn so that the steel wire is parallel to the two roller stands, and finally connected to the wire drawing machine.

[0045] Start the wire drawing machine, which pulls the steel wire to move. The steel wire drives the lower roller 9 and the upper roller 10 to rotate, and the steel wire is rolled during the rotation. The first roller stand 2 rolls the steel wire into a flat steel wire with a short side length of 0.35±0.01mm and a compression rate of 15%. The second roller stand 6 further rolls the flat steel wire to a short side of 0.32±0.01mm and a compression rate of 16%. The flat steel wire rolled by the two-step method is relatively gentle in the rolling process compared to the one-step rolling method. The rolled flat steel wire is less damaged, the number of microcracks on the flat steel wire is reduced, the breaking force reaches more than 300N, and the bidirectional torsion reaches more than 50 times, which effectively reduces the probability of wire breakage during the stranding process.

[0046] The embodiments described above are only preferred embodiments of the invention and are not intended to limit the scope of implementation of the invention. Therefore, any equivalent changes or modifications made according to the technical solutions described in the patent scope of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A two-step method for producing flat steel wire, characterized in that: The method comprises the following steps: A. Rough drawing process: After the wire rod is pickled and surface boronized, it enters the rough drawing equipment. The rough drawing process draws the wire rod to the corresponding smooth steel wire specifications; B. Intermediate heat treatment process: put the smooth steel wire into the heat treatment furnace for water bath quenching; C. Middle drawing process: the steel wire which has been heat treated in the middle is further drawn to reduce the diameter of the steel wire; D. Heat treatment and electroplating process: The steel wire after intermediate drawing is heat treated, and then copper and zinc are electroplated on the surface of the steel wire respectively, and finally a brass alloy is formed on the surface of the steel wire through thermal diffusion; E. Water tank process: Use a water tank wire drawing machine to further draw the electroplated steel wire in the lubricant in the water tank to draw the steel wire into a round steel wire of a specified size; F. Two-step rolling process: the round steel wire is rolled twice, the compression rate of the first rolling is 15%, and the compression rate of the second rolling is 16%, and the finished flat steel wire is obtained; The device used in the two-step rolling process comprises a base (1), a roll frame is provided on the base (1), an adjustment plate (3) is provided on the roll frame, the adjustment plate (3) and the roll frame are both in an inverted "U" shape, the adjustment plate (3) is sleeved on the roll frame, a lower roll (9) and an upper roll (10) are provided in the opening of the roll frame, the lower roll (9) is rotatably connected to the roll frame, a waist-shaped hole is provided at a position of the roll frame corresponding to the upper roll (10), the rotation axis of the upper roll (10) passes through the waist-shaped hole and is rotatably connected to two vertical plates of the adjustment plate (3), an adjustment mechanism (7) is provided above the horizontal plate of the adjustment plate (3), and the adjustment mechanism (7) passes through the horizontal plate of the adjustment plate (3) and is connected to the roll frame; The wire drawing machine pulls the steel wire to move, and the steel wire drives the lower roller (9) and the upper roller (10) to rotate, and the steel wire is rolled during the rotation process.

2. A two-step method for producing flat steel wire according to claim 1, characterized in that: The heat treatment is to heat the steel wire to 900-1100°C.

3. A two-step method for producing flat steel wire according to claim 1, characterized in that: The diameter of the round steel wire obtained in step E is 0.38±0.01mm. The first rolling is to roll the round steel wire with a diameter of 0.38±0.01mm into a flat steel wire with a long side of 0.39±0.01mm and a short side of 0.35±0.01mm. The second rolling is to further roll the steel wire after the first rolling into a finished flat steel wire with a long side of 0.41±0.01mm and a short side of 0.32±0.01mm.

4. A two-step method for producing flat steel wire according to claim 1, characterized in that: The rolling roll stand comprises a first rolling roll stand (2) and a second rolling roll stand (6) which are arranged parallel to each other.

5. A two-step method for producing flat steel wire according to claim 4, characterized in that: The spacing between the lower roller (9) and the upper roller (10) on the first roller stand (2) is 0.35±0.01 mm, and the spacing between the lower roller (9) and the upper roller (10) on the second roller stand (6) is 0.32±0.01 mm.

6. A two-step method for producing flat steel wire according to claim 4, characterized in that: A connecting plate (4) is provided on the front side of the first rolling frame (2), the connecting plate (4) is in an "L" shape, the horizontal plate of the connecting plate (4) is fixed to the first rolling frame (2), the vertical plate of the connecting plate (4) is provided with an adjustment hole, a positioning piece (5) is provided on the adjustment hole, the end of the positioning piece (5) is drum-shaped, a wire hole is provided on the plane end of the positioning piece (5), and the wire hole is located between the lower rolling roll (9) and the upper rolling roll (10).

7. A two-step method for producing flat steel wire according to claim 4, characterized in that: The maximum distance between the rear end of the first rolling stand (2) and the front end of the second rolling stand (6) is 10 cm.

Images