Tungsten wire rod rolling apparatus and tungsten wire rod rolling process

Abstract

This invention provides a tungsten wire rolling equipment and process. The design focuses on the equipment and process, specifically optimizing the number of rolls, roll diameter, feed and discharge temperatures of the tungsten wire, and roll speed to ensure that 8.9mm tungsten wire can be rolled into high-quality 5.2mm tungsten wire. The equipment uses six rolls, with optimized diameter settings for each roll. The feed temperature for the tungsten wire is 1500-1700℃, and the discharge temperature is 900-1200℃. The mill speeds are 1280 r / min (main motor), 1200 r / min (auxiliary motor one), and 1300 r / min (auxiliary motor two). By combining the compression ratio, temperature, and roll speed, the produced 5.2mm tungsten wire is guaranteed to have superior mechanical properties and surface quality.

Description

Technical Field

[0001] This invention relates to the field of metal machining technology, and more specifically, to a tungsten wire rolling equipment and a tungsten wire rolling process. Background Technology

[0002] Tungsten wire is mainly used in the manufacture of lamp filaments and high-speed cutting alloy steel, and also in optical and chemical instruments. Currently, the industry standard for tungsten wire production is to first roll large-diameter bars into rods with a diameter of 8.9 mm, then further reduce the rod size to 5.2 mm through rotary forging, and finally draw them into even finer tungsten wires. 8.9 mm and 5.2 mm are standard dimensions in the industry's tungsten wire production process.

[0003] For example, the invention patent with authorization announcement number CN117888013B, entitled "A Tungsten Alloy Wire and Its Preparation Method and Application," produces alloy rods with diameters of 8.0–12.0 mm. These rods are then forged using a multi-pass continuous rotary forging machine to obtain alloy rods with diameters of 2.5–4.0 mm. However, in actual production, the temperature fluctuations during rotary forging are significant, leading to quality defects in the produced rods. Furthermore, the uniformity of the grains in the rotary-forged rods is poor, which is detrimental to subsequent processing. Processing a rod from 8.9 mm to 5.2 mm using rotary forging takes nearly 30 minutes, resulting in low processing efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology in terms of poor processing quality and low efficiency. The invention provides a tungsten wire rolling equipment and a tungsten wire rolling process, which can improve processing efficiency and obtain 5.2mm tungsten wire with superior mechanical properties and surface quality.

[0005] A tungsten wire rolling equipment includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged in sequence. The rolling mill includes six rolls with diameters decreasing sequentially: 7.2±0.2mm, 6.9±0.2mm, 5.7±0.2mm, 5.3±0.2mm, 5.0±0.2mm, and 4.8±0.2mm.

[0006] The tungsten wire rolling equipment of this invention is used for rolling tungsten wires from 8.9mm to 5.2mm in diameter. The 5.2mm tungsten wires are then used for further drawing into finer tungsten wires. The feeding mechanism is an automatic feeding mechanism that feeds the 8.9mm tungsten wires into a pre-firing furnace. The pre-firing furnace heats and maintains the temperature of the wires to ensure the feed temperature when the tungsten wires enter the first rolling mill and the discharge temperature when they exit the sixth rolling mill.

[0007] It should be noted that the diameter of the last roll in this invention is 4.8mm, not 5.2mm. This is because tungsten wire will spring back after rolling. This invention obtains the final diameter of the six rolls by combining the compression ratio of the six rolls with temperature, temperature loss conditions, rolling speed, wire springback, and product quality requirements, which can ensure that a high-quality 5.2mm tungsten wire is obtained.

[0008] Preferably, the diameters of the six rolls are 7.2 mm, 6.9 mm, 5.7 mm, 5.3 mm, 5.0 mm and 4.8 mm respectively.

[0009] Furthermore, the rolls are driven by a motor.

[0010] The present invention also provides a tungsten wire rolling process, wherein a tungsten wire with a diameter of 8.9 mm is rolled through the six rolls and cooled to form a tungsten wire with a diameter of 5.2 mm.

[0011] Furthermore, during rolling, the feed temperature of the wire entering the first roll is 1500-1700℃, and the output temperature from the last roll is 900-1200℃.

[0012] Furthermore, the feed temperature and discharge temperature are controlled by the pre-firing furnace, and the holding time of the pre-firing furnace is 20-30 minutes. Preferably, the holding time of the pre-firing furnace is 28 minutes.

[0013] Existing technology, when rolling 8.9mm bars, uses shorter raw materials that can be fed into the mill quickly after heating, resulting in minimal heat loss and eliminating the need for a furnace for insulation. However, rolling 5.2mm bars requires longer raw materials, leading to longer feeding times and necessitating a furnace at the feed inlet to reduce heat loss during the mill's entry. Therefore, this invention incorporates a pre-heating furnace before the bars enter the mill to heat and maintain their temperature. This ensures that the bars are heated and kept warm as they enter the rolls, while the portion not yet entering the rolls is protected, guaranteeing the optimal feed temperature for the bars entering the rolls.

[0014] Furthermore, the rolls are driven by motors, which include a main motor, an auxiliary motor one, and an auxiliary motor two. The main motor drives the first, second, third, and fourth rolls, the auxiliary motor one drives the fifth roll, and the auxiliary motor two drives the sixth roll. The power of the main motor is greater than that of the auxiliary motor one and the auxiliary motor two. The main motor has a rotational speed of 1280 r / min, the auxiliary motor one has a rotational speed of 1200 r / min, and the auxiliary motor two has a rotational speed of 1300 r / min.

[0015] The main motor described in this invention drives four rollers to rotate, and the power of the main motor is greater than the power of the auxiliary motor one and the auxiliary motor two.

[0016] Furthermore, the feeding speed of the feeding mechanism is 0.4-0.55 m / s, preferably 0.5 m / s.

[0017] The present invention has the following beneficial effects: This invention discloses a tungsten wire rolling equipment and process. The design focuses on the equipment and process, specifically the number of rolls, roll diameter, feed and discharge temperatures of the tungsten wire, and roll speed, ensuring that 8.9mm tungsten wire can be rolled into high-quality 5.2mm tungsten wire. The equipment comprises six rolls with diameters of 7.2±0.2mm, 6.9±0.2mm, 5.7±0.2mm, 5.3±0.2mm, 5.0±0.2mm, and 4.8±0.2mm, respectively. The feed temperature of the tungsten wire is 1500-1700℃, and the discharge temperature is 900-1200℃. The mill speed is 1280r / min (main motor), 1200r / min (auxiliary motor one), and 1300r / min (auxiliary motor two). The combination of these compression ratios, temperatures, and roll speeds ensures that the produced 5.2mm tungsten wire possesses superior mechanical properties and surface quality. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figures 1(a) to 1(f) are metallographic images of tungsten wire obtained by a tungsten wire rolling process in Example 6. Detailed Implementation

[0019] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0020] Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0023] Existing technology processes tungsten rods to 8.9mm and then further processes them into 5.2mm tungsten wire using rotary forging. However, in actual production, the temperature fluctuations during rotary forging are significant, leading to quality defects in the produced rods. Furthermore, the rotary-forged rods exhibit poor grain uniformity, which is detrimental to subsequent processing. Processing a rod from 8.9mm to 5.2mm using rotary forging takes nearly 30 minutes, resulting in low efficiency. This invention addresses these quality and efficiency issues by designing solutions from both equipment and process perspectives.

[0024] Example 1 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.2 mm, 6.9 mm, 5.7 mm, 5.3 mm, 5.0 mm, and 4.8 mm. The rolls are driven by a motor.

[0025] Example 2 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.0 mm, 6.7 mm, 5.5 mm, 5.1 mm, 4.8 mm, and 4.6 mm. The rolls are driven by a motor.

[0026] Example 3 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.4 mm, 7.3 mm, 5.9 mm, 5.5 mm, 5.2 mm, and 5.0 mm. The rolls are driven by a motor.

[0027] Example 4 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.3 mm, 7.0 mm, 5.8 mm, 5.4 mm, 5.1 mm, and 4.9 mm. The rolls are driven by a motor.

[0028] Example 5 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.1 mm, 6.8 mm, 5.6 mm, 5.2 mm, 4.9 mm, and 4.7 mm. The rolls are driven by a motor.

[0029] Comparative Example 1 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.0 mm, 6.5 mm, 5.9 mm, 5.4 mm, 5.2 mm, and 4.9 mm. The rolls are driven by a motor.

[0030] Comparative Example 2 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.0 mm, 6.5 mm, 5.7 mm, 5.3 mm, 5.0 mm, and 4.6 mm. The rolls are driven by a motor.

[0031] Comparative Example 3 A tungsten wire rolling apparatus includes a feeding mechanism, a pre-firing furnace, and a rolling mill arranged sequentially. The rolling mill includes six rolls with decreasing diameters of 7.0 mm, 6.5 mm, 5.7 mm, 5.3 mm, 5.0 mm, and 4.8 mm. The rolls are driven by a motor.

[0032] Example 6 A tungsten wire rolling process is disclosed, wherein a tungsten wire with a diameter of 8.9 mm is rolled using a tungsten wire rolling equipment described in Comparative Examples 1-3 and Example 1, respectively.

[0033] During rolling, the feed temperature of the wire entering the first roll is 1500-1700℃, and the exit temperature from the last roll is 900-1200℃. The feed and exit temperatures are controlled by the pre-firing furnace, which maintains its temperature for 20-30 minutes; in this embodiment, the pre-firing furnace maintains its temperature for 28 minutes. The rolls are driven by motors, including a main motor, auxiliary motor one, and auxiliary motor two. The main motor drives the first, second, third, and fourth rolls; auxiliary motor one drives the fifth roll; and auxiliary motor two drives the sixth roll. The main motor has a higher power than auxiliary motors one and two. The main motor's speed is 1280 r / min; auxiliary motor one's speed is 1200 r / min; and auxiliary motor two's speed is 1300 r / min. The feeding speed of the feeding mechanism is 0.5 m / s.

[0034] Using the process parameters described in this embodiment—feed temperature, discharge temperature, holding time, motor speed, and feeding speed—the effects of wires processed with different roll sizes in Comparative Examples 1-3 and Example 1 are compared, as shown in Table 1. Table 1

[0035] Through research, this invention has found that the roll dimensions described in Example 1, combined with the process parameters in Example 6 regarding feed temperature, discharge temperature, holding time, motor speed, and feeding speed, can produce 5.2mm tungsten wire with superior mechanical properties and surface quality.

[0036] The following section examines temperature: Comparative Example 4 The difference between Comparative Example 4 and Example 6 is that the feed temperature and discharge temperature of Comparative Example 4 are not within the temperature range of Example 6 (feed temperature is 1500-1700℃, discharge temperature is 900-1200℃). The feed temperature of Comparative Example 4 is 1748℃ and the discharge temperature is 1266℃.

[0037] Comparative Example 5 The difference between Comparative Example 5 and Comparative Example 4 is that the feed temperature is 1701℃ and the discharge temperature is 1206℃.

[0038] Example 7 The difference between Example 7 and Comparative Example 5 is that the feed temperature is 1655°C and the discharge temperature is 1162°C, which are within the temperature range of Example 6.

[0039] Example 8 The difference between Example 8 and Example 7 is that the feed temperature is 1589°C and the discharge temperature is 1082°C, which are within the temperature range of Example 6.

[0040] Example 9 The difference between Example 9 and Example 8 is that the feed temperature is 1520°C and the discharge temperature is 998°C, and the feed temperature and discharge temperature are within the temperature range of Example 6.

[0041] Comparative Example 6 The difference between Comparative Example 6 and Example 9 is that the feed temperature is 1499°C and the discharge temperature is 959°C, which are outside the temperature range of Example 6.

[0042] Comparative Example 7 The difference between Comparative Example 7 and Comparative Example 6 is that the feed temperature is 1458°C and the discharge temperature is 959°C, which are outside the temperature range of Example 6.

[0043] Table 2

[0044] As shown in Table 2, when the feed temperature is less than 1500℃ or greater than 1700℃, and the discharge temperature is greater than 1200℃, the final tungsten rod is brittle and prone to splitting, which is detrimental to subsequent processing. In Examples 6-8, when the feed temperature is 1500-1700℃ and the discharge temperature is 900-1200℃, the rod material has a normal feel when tapped and good surface quality.

[0045] Key process parameters of a rolling mill include compression ratio, rolling temperature (feed temperature and discharge temperature), and rolling speed. The roll size controls the compression ratio. Insufficient compression ratio will result in a loose and defective internal structure of the product, leading to substandard mechanical properties; excessive or uneven compression ratio will result in excessive internal stress, thereby causing cracks.

[0046] The feed temperature and discharge temperature together control the temperature of the entire processing. Tungsten has the characteristics of "high toughness and low brittleness." At low temperatures, tungsten material is brittle and will split during rolling. Therefore, the pressure processing of tungsten material must be carried out at high temperatures. However, if the processing temperature is too high, it will cause the tungsten grains to grow excessively, resulting in brittle tungsten rods that are not conducive to subsequent processing. In addition, excessively high processing temperatures will shorten the service life of rolling mill components and increase production costs.

[0047] Besides controlling the compression ratio and feed / discharge temperatures, the rotational speed of the rolls controls the rolling speed and rhythm, and an appropriate rotational speed is crucial. Too low a speed will cause the workpiece to remain in the deformation zone for too long, resulting in severe heat loss, increased deformation resistance, and may even prevent it from rolling in subsequent passes; too high a speed will lead to an excessively high strain rate, reduced plasticity, and increased risk of cracking.

[0048] Therefore, compression ratio, temperature control of feed and discharge materials, and roll speed are challenging aspects of the rolling process.

[0049] Based on the determined motor power and speed of the equipment, this invention studies the size of the rolls, the rolling temperature, and the roll speed to ensure that 8.9mm tungsten wire can be rolled into 5.2mm tungsten wire with superior mechanical properties and surface quality. Existing technology using a rotary hammer to process 8.9mm to 5.2mm tungsten rods requires nearly 30 minutes, while the rolling method of this invention only takes a little over 3 seconds, greatly improving production efficiency. Figure 1 shows the metallographic image of the tungsten wire obtained under the process parameters of Example 6. Figure 1 shows metallographic images of different parts of the same product. The metallographic images show that the formed tungsten wire has uniform grains.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A tungsten wire rolling equipment, characterized in that, The device includes a feeding mechanism, a preheating furnace, and a rolling mill arranged in sequence. The rolling mill includes six rolls with decreasing diameters: 7.2±0.2mm, 6.9±0.2mm, 5.7±0.2mm, 5.3±0.2mm, 5.0±0.2mm, and 4.8±0.2mm.

2. The tungsten wire rolling equipment according to claim 1, characterized in that, The diameters of the six rolls are 7.2mm, 6.9mm, 5.7mm, 5.3mm, 5.0mm and 4.8mm respectively.

3. The tungsten wire rolling equipment according to claim 2, characterized in that, The rollers are driven by a motor.

4. A tungsten wire rolling process, characterized in that, Using the tungsten wire rolling equipment according to any one of claims 1-3, a tungsten wire with a diameter of 8.9 mm is rolled through the six rolls and cooled to form a tungsten wire with a diameter of 5.2 mm.

5. The tungsten wire rolling process according to claim 4, characterized in that, During rolling, the feed temperature of the wire entering the first roll is 1500-1700℃, and the output temperature from the last roll is 900-1200℃.

6. The tungsten wire rolling process according to claim 5, characterized in that, The feed temperature and discharge temperature are controlled by the pre-firing furnace, and the holding time of the pre-firing furnace is 20-30 minutes.

7. The tungsten wire rolling process according to claim 6, characterized in that, The preheating furnace is kept warm for 28 minutes.

8. The tungsten wire rolling process according to claim 5, characterized in that, The rolls are driven by motors, including a main motor, an auxiliary motor one, and an auxiliary motor two. The main motor drives the first, second, third, and fourth rolls, the auxiliary motor one drives the fifth roll, and the auxiliary motor two drives the sixth roll. The power of the main motor is greater than that of the auxiliary motors one and two. The main motor has a rotational speed of 1280 r / min, the auxiliary motor one has a rotational speed of 1200 r / min, and the auxiliary motor two has a rotational speed of 1300 r / min.

9. A tungsten wire rolling process according to claim 8, characterized in that, The feeding speed of the feeding mechanism is 0.4-0.55 m / s.

10. A tungsten wire rolling process according to claim 9, characterized in that, The feeding speed of the feeding mechanism is 0.5 m / s.

Images