A wire drawing die matching method

Abstract

The present invention relates to a wire drawing die matching method, wherein the method comprises the following steps: measuring the temperature of the steel wire at the outlet of the wire drawing die in each drawing pass, and adjusting the compression rate of the corresponding pass according to the measured temperature. The method of the present invention starts from the mechanism that affects the plasticity of the finished steel wire, and solves the problem that the empirical die matching is not universal from the source. The temperature of the steel wire during the drawing process aggravates the aging hardening of the steel wire. As long as the temperature is too high at a certain stage in the entire wire drawing process, the plasticity of the steel wire will be greatly reduced. The present invention is based on the accurate measurement of the temperature of the steel wire in each drawing pass combined with the traditional empirical die matching to adjust the compression rate of a single drawing pass, which can improve the plasticity of the steel wire while improving the production efficiency. The method of the present invention has universality and is suitable for all cold drawing conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of steel wire production, and in particular relates to a wire drawing die matching method. Background Art

[0002] Most wire products need to be cold drawn before use. Cold drawing is a process of hardening. After drawing, the strength of the steel wire increases and the plasticity decreases. Products such as rope wire and cable wire have high requirements for plasticity. The production process must be tested for plasticity indicators such as torsion and bending. The steel wire releases a large amount of deformation heat during the cold drawing process. About 90% of the mechanical energy consumed in the wire drawing is converted into heat energy in the deformation zone of the wire drawing die, and the remaining less than 10% of the energy exists in the wire after drawing as potential energy (lattice distortion and hardening). The drawing heat causes the temperature of the steel wire to rise sharply. If the temperature is not properly controlled, the deformed steel wire will undergo aging hardening, greatly reducing the plasticity of the steel wire. The temperature of the steel wire is closely related to lubrication, die design and cooling of the reel. The existing wire drawing die matching is mainly based on experience. First, the total compression rate is determined based on the strength of the raw material and the finished product, and then the compression rate of each pass is calculated based on the drawing passes of the equipment, so as to determine the size of the wire drawing die for each pass. The general principle is that the compression rate of medium and high carbon steel in a single pass is not more than 25%, and that of low carbon steel is not more than 30%. When matching the mold, the compression rate of the second pass is generally the largest, and the subsequent passes are reduced in sequence. This mold matching method only considers the effect of the drawing deformation on the uniformity of the steel wire structure. When the same cooling method is used, the temperature of the steel wire in some passes will be too high, which is difficult to meet the production needs of some steel wires with higher plasticity requirements.

[0003] The existing method of matching molds based on experience is not universal. Usually, when producing according to experience, the temperature of the steel wire in the middle passes is significantly higher than that of the first and last passes, and there are also large differences in the temperature of each pass. The temperature of the steel wire is also related to the lubrication of each pass, the structure of the wire drawing die and the cooling of the wire drawing equipment. In many cases, the traditional empirical die matching will cause the temperature of some passes of the steel wire to be too high, resulting in a significant decrease in the plasticity indicators such as torsion and bending of the finished steel wire. In order to ensure the plasticity of the steel wire, the usual practice is to reduce the overall temperature of the steel wire in each pass by reducing the drawing speed, but this method comes at the expense of production efficiency.

[0004] In view of the above reasons, the present invention is proposed. Summary of the invention

[0005] In order to solve the problem that the drawing die matching method in the prior art may cause the temperature of some passes to be too high, thereby significantly reducing the plasticity indicators of the steel wire such as torsion and bending, the present invention provides a wire drawing die matching method. The method of the present invention accurately measures the temperature of the steel wire in each pass, adjusts the compression rate of the corresponding pass according to the measured temperature, so that the temperature of each pass is in a balanced state, which can improve the plasticity of the steel wire and improve production efficiency at the same time.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A wire drawing die matching method, the method comprising the following steps: measuring the temperature of the steel wire at the outlet of the wire drawing die in each drawing pass, and adjusting the compression rate of the corresponding pass according to the measured temperature.

[0008] Furthermore, if the steel wire is made of medium-high carbon steel, the compression rate of each pass is ≤25%;

[0009] If the steel wire is made of low carbon steel, the compression rate of each pass shall be ≤30%.

[0010] Furthermore, if the temperature of the steel wire at the outlet of the wire drawing die in any pass is measured to be higher than 140°C, firstly, the compression rate of the corresponding pass is reduced until the temperature of the steel wire at the outlet of the wire drawing die in that pass is lower than 140°C; secondly, the compression rate of at least one pass in which the temperature of the steel wire at the outlet of the wire drawing die is lower than 140°C is increased to keep the total compression rate of the steel wire unchanged.

[0011] Furthermore, if the temperature of the steel wire at the outlet of the wire drawing die in any pass is measured to be ≤90°C, first, the compression rate of the corresponding pass is increased, and the temperature of the steel wire at the outlet of the wire drawing die in this pass is lower than 140°C. Secondly, the compression rate of at least one pass where the temperature of the steel wire at the outlet of the wire drawing die is 90<T≤140°C is reduced to keep the total compression rate of the steel wire unchanged.

[0012] Furthermore, if the temperature of the steel wire at the outlet of the wire drawing die in each pass is measured to be lower than 140°C, the wire drawing speed is increased, and the temperature of the steel wire at the outlet of the wire drawing die in each pass is measured to be lower than 140°C.

[0013] Furthermore, the temperature of the steel wire at the outlet of the drawing die in each drawing pass is measured by contact or non-contact method.

[0014] Furthermore, the temperature of the steel wire at the outlet of the drawing die in each drawing pass is measured by a thermal imager or a contact temperature meter.

[0015] The present invention adjusts the single-pass compression rate of the wire drawing die according to the measured temperature of the steel wire at the outlet of the wire drawing die, and measures the temperature of the steel wire at the outlet of each pass after the adjustment. The above process is repeated to adjust the temperature of each pass to the same level. The method of the present invention is based on adjusting the compression rate of each pass while keeping the total compression rate (compression rate from raw materials to finished products) unchanged compared with the traditional die matching.

[0016] The wire drawing pass compression ratio is the reduction ratio of the wire area after drawing, that is, Q = (S0-S1) / S0, where Q is the pass compression ratio, S0 and S1 are the cross-sectional areas of the wire before and after drawing. Assuming that the wire needs to be drawn n times, the final total compression ratio of the wire is: Q = (S0-S n ) / S0=1-(S1 / S0)(S2 / S1)…(S n / S n-1 ).

[0017] The principle of the present invention is to optimize the die matching by measuring the temperature of the steel wire at the exit of the drawing die in each drawing pass on the basis of the traditional die matching. Through experimental research, it is found that the temperature of the steel wire when it exits the die cannot be higher than 140℃. Once it exceeds this temperature, the steel wire will undergo aging hardening in a short time, reducing the plasticity indexes such as torsion and bending of the steel wire.

[0018] The present invention is achieved by the following means: first, the die is matched according to the traditional die matching method, and the temperature of the steel wire at the outlet of each drawing die is accurately measured by contact or non-contact method during the drawing process. Then, the drawing die with a steel wire temperature higher than 140°C is adjusted to reduce its pass compression rate, while increasing the pass compression rate with a temperature far lower than 140°C. By repeating the above steps, the temperature of the steel wire at the outlet of the drawing die of each drawing pass tends to be consistent, and none of them is higher than 140°C. Finally, the adjusted drawing die chain is used as the final die chain. At this point, the temperature-based die matching process is completed.

[0019] When other drawing die parameters and drum cooling remain unchanged, the outlet temperature of the wire drawing die will increase if only the compression rate is increased. However, the outlet temperature of the wire drawing die is also related to the diameter of the steel wire. Under the same compression rate, the larger the diameter of the steel wire, the more difficult it is for the steel wire to dissipate heat and the higher the temperature. In addition, the temperature of the steel wire outlet is also related to the lubrication of the steel wire. Therefore, there are certain differences in the relationship between the single-pass compression rate and temperature of the wire drawing die in different production lines. However, for the same production line, when other parameters remain unchanged, there is a fixed relationship between the change in the compression rate of the wire drawing die and the temperature change. To this end, the compression rate and temperature data of each pass of the production line can be collected, and a relationship diagram between the two can be drawn up. Subsequent adjustments can be made with reference to the relationship diagram.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The method of the present invention starts from the mechanism that affects the plasticity of the finished steel wire, and solves the problem of the low universality of empirical die matching from the source. The temperature of the steel wire during the drawing process intensifies the aging hardening of the steel wire. As long as the temperature is too high at a certain stage in the entire wire drawing process, the plasticity of the steel wire will be greatly reduced. The present invention is based on the accurate measurement of the temperature of the steel wire in each drawing pass combined with the traditional empirical die matching to adjust the single-pass drawing compression rate, which can improve the plasticity of the steel wire while improving production efficiency. The method of the present invention is universal and applicable to all cold drawing conditions. DETAILED DESCRIPTION

[0022] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0023] Example 1

[0024] 14mm wire rod with a carbon content of 0.92% is used to produce 6.95mm steel wire. The steel wire is drawn using 7 drawing passes. The drawing deformation of passes 1 to 7 is shown in Table 1.

[0025] First, the die matching is calculated according to conventional die matching rules. The compression ratio of the die matching pass and the die exit temperatures of each drawing pass measured during production according to the compression ratio are shown in Table 1 Process 1. The torsional properties of the obtained steel wire are shown in Table 2 Process 1.

[0026] Table 1

[0027]

[0028] Table 2

[0029] performance Process 1 Craft 2 Craft 3 Twist times 16 / 24 / 8 / 20 / 19 32 / 32 / 34 / 35 / 34 34 / 33 / 33 / 35 / 34 Torsion fracture type Partial brittle fracture Ductile fracture Ductile fracture

[0030] As can be seen from Table 1, in process 1, the temperature at the die outlet in the second and third passes is higher than 140°C, the torsional performance of the steel wire is poor, the number of torsions is low, and the torsional fracture of some steel wires is brittle. Therefore, according to the method described in this application, the compression rate of each pass can be adjusted while the total compression rate (compression rate from raw materials to finished products) remains unchanged, and the compression rate of the pass with too high temperature is appropriately reduced, and the compression rate of the pass with low temperature is increased, so that the temperature of the steel wire is reduced to below 140°C. The adjusted pass compression rate, die outlet temperature and torsional performance of the obtained steel wire are shown in Table 1 and Process 2 in Table 2. It can be seen that by adjusting the pass compression rate, the temperature of the steel wire is reduced to below 140°C, and the number of torsions of the steel wire is significantly increased, and its torsional fracture is also completely plastic.

[0031] Since the temperature of each pass in process 2 has a certain distance from the upper limit of control (140°C), the wire drawing speed can be increased on the basis of process 2. When the speed is increased from 2m / s to 3.5m / s, the die exit temperature of each pass of steel wire and the torsional properties of the obtained steel wire are shown in Table 1 and Process 3 of Table 2. It can be seen that after increasing the wire drawing speed, the temperature of each pass of steel wire is still maintained below 140°C. The mechanical properties of the steel wire are shown in Process 3 of Table 2, and its torsional properties are also significantly improved compared with Process 1.

[0032] Example 2

[0033] 1.0 mm steel wire is produced using 3.0 mm heat-treated steel wire with a carbon content of 0.60%. The steel wire is drawn using 11 passes at a drawing speed of 8 m / s. The drawing deformation of passes 1-11 is shown in Table 3.

[0034] Table 3

[0035]

[0036] Table 4

[0037] performance Process 1 Craft 2 Twist times 25 / 20 / 23 / 16 / 26 35 / 32 / 36 / 34 / 34 Bending times 14 / 12 / 16 / 15 / 12 22 / 21 / 23 / 22 / 21

[0038] First, the mold matching is calculated according to the conventional mold matching rules. The obtained pass compression ratio after mold matching and the die exit temperature of each drawing pass measured during production according to the pass compression ratio are shown in Table 3 Process 1. It can be seen that the die exit temperature in the second and third passes is higher than 140°C, while the die exit temperature of the last two passes is ≤90°C. Therefore, the pass compression ratio can be adjusted according to the measured temperature, the compression ratio of the first 9 passes can be appropriately reduced, and the compression ratio of the last two passes can be increased. The adjusted pass compression ratio and die exit temperature are shown in Table 3 Process 2.

[0039] Through the above adjustments, the temperature of the steel wire at the die outlet of each pass tends to be uniform, and the torsion and bending properties of the steel wire under the corresponding two processes are shown in Table 4. It can be seen that through the adjustment based on this technology, the torsion and bending properties of the steel wire have been significantly improved.

[0040] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A wire drawing die matching method, characterized in that: The method comprises the following steps: measuring the temperature of the steel wire at the outlet of the wire drawing die at each drawing pass, and adjusting the compression rate of the corresponding pass according to the measured temperature; If the steel wire is made of medium-high carbon steel, the compression rate of each pass shall be ≤25%; If the steel wire is made of low carbon steel, the compression rate of each pass shall be ≤30%; If the measured temperature of the steel wire at the outlet of the wire drawing die in any pass is higher than 140°C, firstly, reduce the compression rate of the corresponding pass until the temperature of the steel wire at the outlet of the wire drawing die in that pass is lower than 140°C; secondly, increase the compression rate of at least one pass in which the temperature of the steel wire at the outlet of the wire drawing die is lower than 140°C to keep the total compression rate of the steel wire unchanged.

2. A wire drawing die matching method according to claim 1, characterized in that: If the temperature of the steel wire at the outlet of the wire drawing die in any pass is measured to be ≤90℃, firstly, the compression rate of the corresponding pass is increased, and the temperature of the steel wire at the outlet of the wire drawing die in this pass is lower than 140℃. Secondly, the compression rate of at least one pass where the temperature of the steel wire at the outlet of the wire drawing die is 90<T≤140℃ is reduced to keep the total compression rate of the steel wire unchanged.

3. A wire drawing die matching method according to claim 1 or 2, characterized in that: The temperature of the steel wire at the outlet of the drawing die in each drawing pass is measured by contact or non-contact method.

4. A wire drawing die matching method according to claim 3, characterized in that: The temperature of the steel wire at the outlet of the drawing die in each drawing pass is measured using a thermal imager or a contact temperature meter.

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