Rope forming process of 2 / 7UT ultrahigh-strength steel wire cord

Abstract

The invention discloses a rope forming process of a 2 / 7UT ultrahigh-strength steel wire cord, which comprises the following steps: (1) carrying out dry drawing on an 86C wire rod with the diameter of 5.5 mm to obtain a dry-drawn steel wire; (2) carrying out austenitizing treatment on the dry steel wire, carrying out electroplating and thermal diffusion to obtain a brass wire plated with a copper-zinc alloy on the surface, and taking up the brass wire on a spool; (3) wet-drawn steel wires are obtained through wet-drawing equipment, the wet-drawn steel wires are subjected to 23-pass drawing in total, a 21 'die, a 22' die and a 23 'die are additionally arranged in the 21 pass, the 22 pass and the 23 pass respectively, and the 21' die, the 22 'die and the 23' die are located between the corresponding current-pass die and the previous-pass die respectively; and (4) taking two wet drawing steel wires as an inner layer, taking seven wet drawing steel wires as an outer layer, and performing one-time twisting forming according to the same twisting direction and the same twisting length. Compared with 6 * 1 UT, the breaking force and the diameter are equivalent, the 2 / 7 CCUT manufacturing process requirement is lower, the cord thread finished product quality is higher, process adjustment can be reduced, and cost can be reduced; and meanwhile, the structure is fully glued, so that internal gaps are reduced under the condition of ensuring the adhesive force.

Description

Technical Field

[0001] The invention relates to a 2 / 7UT ultra-high-strength steel cord, and in particular to a rope-forming process of the 2 / 7UT ultra-high-strength steel cord. Background Art

[0002] At present, steel cord has been maturely used as a skeleton material in tires. As tires develop towards green, low-carbon and environmentally friendly, higher strength and smaller diameter cords are needed to reduce the amount of steel wire in tires, thereby reducing tire weight, reducing rolling resistance, and increasing the driving speed of the car. Figure 1 (as shown) is a common tire belt specification, widely used in TBR tires. This product adopts a double-layer structure with different lay lengths. Since the layers are in point contact, it is easy to cause damage to the steel wire. The 6x1UT structure that has been developed and produced will be replaced, but the 6x1 structure (such as Figure 2 As shown in Figure 2, due to geometrical reasons, the central gap roughly allows a steel wire to easily enter the central position (such as Figure 3 As shown on the left), or due to uneven stress distribution during twisting, one steel wire is squeezed out of the center position, resulting in wire misalignment (as shown on the left). Figure 3 In order to reduce the misalignment of steel wires, the interaction between steel wires is often reduced in production, but this can easily lead to loose cord molding defects. In tire applications, the 6x1 structure causes a large gap in the middle, and the 6 steel wires are in close contact, which makes it difficult for glue to penetrate, reducing the adhesion between the rubber and the rubber. This causes water vapor to be stored in the gap in the center of the cord, which reduces the durability of the tire and reduces the number of tire retreads. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention proposes a 2 / 7UT ultra-high-strength steel cord rope-making process for producing a 2 / 7CCUT steel cord. The 86C wire rod is used, and the steel wire strength reaches 3700MPa. There are two inner layers and seven outer layers. The two layers are twisted once with the same twist direction and twist pitch to form a compact cord structure. Compared with 3+8x0.33HT, the cord breaking tensile force is improved, and the cord diameter is reduced. The amount of steel wire can be reduced under the condition of meeting the tire use strength, thereby reducing the tire rolling resistance and fuel consumption. The steel wires are in line contact, which can improve the fatigue performance and service life of the cord. Compared with 6x1UT, the breaking force and diameter are equivalent, the 2 / 7CCUT manufacturing process requirements are lower, the cord finished product quality is higher, and the process adjustment and cost can be reduced; at the same time, the structure is fully infiltrated with glue, and the internal gap is reduced under the condition of ensuring the adhesion.

[0004] The technical solution adopted by the present invention is: a rope-making process of 2 / 7UT ultra-high-strength steel cord, (1) Dry-drawing 86C wire rod with a diameter of 5.5 mm to obtain dry-drawn steel wire; (2) austenitizing the dry steel wire, electroplating and thermal diffusion to obtain a brass wire with a copper-zinc alloy coating on the surface, and winding the wire on an I-shaped wheel; (3) The wet-drawn steel wire is obtained by wet-drawing equipment. The wet-drawing process is performed through 23 drawing passes. Three dies, 21', 22' and 23', are added to the 21st, 22nd and 23rd passes respectively. The dies, 21', 22' and 23', are located between the corresponding die of the current pass and the die of the previous pass respectively. (4) Two wet-drawn steel wires are used as the inner layer and seven wet-drawn steel wires are used as the outer layer, and they are twisted into shape at one time according to the same twist direction and twist length.

[0005] On the basis of the above scheme, as a preferred embodiment, the twisting process is: the two middle steel wires are core strands that pass through the center hole of the distribution disk without passing through the pre-deformer, and the other seven steel wires pass through the other seven holes of the distribution disk and pass through the pre-deformer respectively, and then the 9 steel wires pass through the die, traction wheel, straightener one, virtual twister, straightener two together, and the resulting steel cord is wound onto the finished I-shaped wheel.

[0006] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses 82D2Cr wire rod to replace 92C to reduce production costs; the chromium content is increased, and the wire rod can significantly improve the material structure and performance after chromium alloying, achieving high strength and high toughness of the material; at the same time, the semi-finished process, wet drawing process, and lubricant concentration parameters are optimized, and the wire breakage rate in the entire production process of UT structural steel cord is reduced and the yield rate is improved while ensuring the quality and performance of the steel cord. The wide application of 82D2Cr wire rod in UT structural steel cord has been achieved, making an important contribution to the lightweight development of tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of the 3+8 structure.

[0008] Figure 2 It is a schematic diagram of the 6×1 structure.

[0009] Figure 3 This is a comparison diagram of the misalignment defects of the 6×1 structure (the left side is a schematic diagram of the misalignment of the steel wire extruding inward, the middle is a schematic diagram of the misalignment of the steel wire extruding outward, and the right side is a schematic diagram of the standard cord cross section).

[0010] Figure 4 It is a schematic diagram of the 2 / 7 structure.

[0011] Figure 5 It is a structural schematic diagram of straightener one.

[0012] Figure 6It is a schematic diagram of cord twisting.

[0013] In the figure: 1-I-shaped wheel; 2-steel wire; 3-distribution plate; 4-pre-deformer; 5-pressing die; 6-traction wheel; 7-straightener 1; 8-virtual twister; 9-straightener 2; 10-cord; 11-take-up spool. DETAILED DESCRIPTION

[0014] The present invention will be further described below by way of examples, but the scope of the present invention is not limited thereto.

[0015] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0016] like Figure 4-6 As shown in the figure, a rope-making process of 2 / 7UT ultra-high-strength steel cord is used. The 86C wire rod is rough-drawn, heat-treated and electroplated, and then wet-drawn and twisted into shape.

[0017] Before twisting, the steel wire is pre-deformed by a sheet-type pre-deformer, and then the wire is ply-ply and twisted. After twisting and forming, it first passes through the straightener 1 to stabilize the stress distribution. After the initial twisting, it is first twisted and untwisted by the virtual twister to effectively eliminate the residual stress of the cord, and then the straightener 2 is used to further improve the cord rope quality. This method improves the forming quality of the cord and also ensures production efficiency and yield rate.

[0018] More importantly, (1) Dry-drawn steel wire is obtained by using 86C wire rod with a diameter of 5.5 mm and mechanically dephosphorizing the surface. (2) The dry steel wire is austenitized, the atmosphere of the heating furnace is properly controlled to ensure the heat treatment process organization, the oxide is removed by pickling, and then the brass wire with copper-zinc alloy plated on the surface is obtained by electroplating and thermal diffusion, and the wire is wound on the I-shaped wheel.

[0019] (3) The brass steel wire is subjected to multiple wet drawing passes to obtain a steel wire that meets the strength and diameter requirements. A coarser alloy specification of 86C is used to control the compression ratio. A total of 23 drawing passes are performed using a wet drawing double-die process. Three dies, 21', 22' and 23', are added to the 21st, 22nd and 23rd passes respectively to share the compression ratio and improve the plasticity of the steel wire, thereby improving the rope quality of the cord twisting.

[0020] (4) Two wet-drawn steel wires are used as the inner layer and seven wet-drawn steel wires are used as the outer layer. They are twisted into shape once according to the same twist direction and twist pitch, and a steel cord with a 2 / 7CCUT structure is obtained. Different twist pitches and twist directions make the twisted steel wires point-contacted. The force contact area of ​​the cord itself is small and the contact friction is large. In the tire application process, the service life of the tire is reduced. With the same twist pitch and twist phase, the force contact area of ​​the cord itself is large and the mutual friction is small, which improves the service life of the tire and increases the number of tire retreading times, which complies with the national green tire development needs.

[0021] The twisting process is as follows: the steel wire is lowered from the I-shaped wheel, the two middle steel wires are core strands that pass through the center hole of the distribution disk without passing through the pre-deformer, the tension of the two middle core strands is set to 6000g, and the tension of the other seven steel wires is set to 1000g, which ensures that the cross-section of the 9 steel wires is flat after the cord is cut. The seven steel wires need to pass through the other seven holes of the distribution disk and pass through the pre-deformer respectively. The function of the pre-deformer is to pre-deform the steel wire in advance to ensure that the cord is not loose after forming, and then the 9 steel wires pass through the die together. The die size is selected as 1.5mm. The function of the die is to make the cord twisted more tightly and evenly. The distance between the die and the rope frame is set to 70mm to ensure that the steel wire has an appropriate deformation amount so that the cord is not loose. At this time, the cord has accumulated a lot of stress after a series of deformations such as twisting, bending, and stretching. In order to eliminate the stress, a suitable winding path is selected. It is first wound around the traction wheel 5 times and then enters the virtual twister. After exiting the virtual twister, it first enters the straightener 1 to eliminate part of the stress. At this time, the speed of the virtual twister will decrease and the stress elimination effect will be weakened. In order to improve the stress elimination effect, it is wound around the traction wheel 2 times and enters the straightener 2 to eliminate the remaining stress, and finally goes to the traction wheel. After the joint action of the traction wheel, straightener 1, virtual twister and straightener 2, the stress is completely eliminated, the rope quality is stable, and the number of process adjustments is reduced. Finally, the final steel cord is wound on the finished I-shaped wheel.

[0022] The 2 / 7x0.335 UT steel cord obtained in this embodiment has similar breaking tensile forces as 3+8x0.33 HT and 6x0.415 UT, but the linear density of 2 / 7x0.335 UT is nearly 16% lower than that of 3+8x0.33 HT. While ensuring the same cord strength, this embodiment can significantly reduce the amount of material used, which is beneficial to the lightweight of the tire. At the same time, the number of molding alarms of the 2 / 7x0.335 UT structure is much lower than that of the 6x0.415 UT structure, which meets the conditions for large-scale production.

[0023] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A rope-making process for 2 / 7UT ultra-high-strength steel cord, characterized in that: (1) Dry-drawing 86C wire rod with a diameter of 5.5 mm to obtain dry-drawn steel wire; (2) austenitizing the dry steel wire, electroplating and thermal diffusion to obtain a brass wire with a copper-zinc alloy coating on the surface, and winding the wire on an I-shaped wheel; (3) The wet-drawn steel wire is obtained by wet-drawing equipment. The wet-drawing process is performed through 23 drawing passes. Three dies, 21', 22' and 23', are added to the 21st, 22nd and 23rd passes respectively. The dies, 21', 22' and 23', are located between the corresponding die of the current pass and the die of the previous pass respectively. (4) Two wet-drawn steel wires are used as the inner layer and seven wet-drawn steel wires are used as the outer layer, and they are twisted into shape at one time according to the same twist direction and twist length.

2. A rope-making process for 2 / 7UT ultra-high-strength steel cord according to claim 1, characterized in that: The twisting process is as follows: the two middle steel wires are core strands that pass through the center hole of the distribution disk without passing through the pre-deformer, and the other seven steel wires pass through the other seven holes of the distribution disk and pass through the pre-deformer respectively. Then the 9 steel wires pass through the die, traction wheel, straightener one, virtual twister, straightener two together, and the resulting steel cord is wound on the finished I-shaped wheel.

3. A 2 / 7UT ultra-high strength steel cord rope-making process as claimed in claim 2, characterized in that: The core strand tension is 6000g.

4. A rope-making process for 2 / 7UT ultra-high-strength steel cord as claimed in claim 2, characterized in that: The tension of the seven wet-drawn steel wires is 1000g.

5. A 2 / 7UT ultra-high strength steel cord rope-making process as claimed in claim 2, characterized in that: The distance between the die and the rope frame is set to 70 mm.

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