Forming method of 7XXX series aluminum alloy small-specification bar blank for bolt

Abstract

The invention relates to a forming method of a 7XXX series aluminum alloy small-specification bar blank for a bolt, in particular to a forming method of a 7XXX series aluminum alloy small-specification bar blank for a bolt. The method aims at solving the problems that an existing 7XXX series aluminum alloy small-specification bar blank for a bolt is long in production period and low in yield due to the fact that an extrusion mode is adopted. The 7XXX series small-specification aluminum alloy bar blank for the bolt is produced in a casting-rolling-drawing mode, a long-root casting rod can be used for directly rolling a wire rod, and finally the wire rod is drawn and cut into the required specification, so that the problem is hopefully solved from the source, the yield is greatly improved, and the production efficiency is remarkably improved. The method is used for forming the 7XXX series aluminum alloy small-specification bar blank for the bolt.

Description

Technical Field

[0001] The invention specifically relates to a method for forming a small-size 7XXX series aluminum alloy bar blank for bolts. Background Art

[0002] In the field of modern industrial manufacturing, bolts are a key connecting component, and their quality and production efficiency have attracted much attention. For small-sized 7XXX series aluminum alloy bar blanks for bolts, the traditional forming process generally follows the process of casting-sawing-extrusion to carry out production operations.

[0003] In this traditional process system, since the aluminum alloy bar billet used in the end is used for bolt manufacturing, its diameter is often small. Based on the demand for such small-diameter finished products, the corresponding cast bar diameter is also designed to be smaller. As a result, in the equipment selection process, in order to adapt to the smaller diameter cast bars, a smaller extruder has to be selected. However, this type of small extruder has a significant limitation, that is, the length of the extrusion billet that can be accommodated is quite limited.

[0004] In actual production, the staff had to cut the long cast bars obtained after aluminum alloy casting, and then put them into the extruder for extrusion one by one. After each extrusion, extrusion residues will be generated, which can no longer be put into the subsequent effective production process. Over time, the yield rate is greatly reduced. For example, in the order task of mass production of aluminum alloy bar blanks for bolts, the frequent occurrence of extrusion residues makes the number of qualified products that can meet the specification requirements far lower than expected, resulting in a waste of raw materials.

[0005] Moreover, the segment-by-segment extrusion method seriously slows down the entire production rhythm. The loading and unloading of each segment of billet, the adjustment of extrusion parameters and other operations require extra time, which greatly prolongs the production cycle. If there is an urgent order or a need for rapid replenishment, the traditional extrusion process is difficult to meet the production demand in a short time, which poses a severe challenge to the company's production scheduling and market responsiveness.

[0006] In view of this, there is an urgent need for a new method for forming small-size 7XXX series aluminum alloy bar billets for bolts to overcome the thorny problems of long production cycle and low yield rate exposed by the existing extrusion method. Summary of the invention

[0007] The present invention aims to solve the problem that the existing 7XXX series aluminum alloy small-sized bar blanks for bolts adopt an extrusion method, which has a long production cycle and a low yield, and provides a forming method for 7XXX series aluminum alloy small-sized bar blanks for bolts.

[0008] A method for forming a 7XXX series aluminum alloy small-size bar blank for bolts is carried out in the following steps:

[0009] The long cast rod formed by casting is heated after milling, and then rolled into a coil after heating to a set temperature to obtain a coil wire; the coil wire is annealed; the annealed coil wire is drawn by a drawing machine, and then subjected to secondary annealing to complete the forming of 7XXX series aluminum alloy small-size bar blanks for bolts.

[0010] Beneficial effects of the present invention:

[0011] The present invention can avoid the casting rod being cut into small sections for use, and at the same time avoid the 10% yield loss caused by cutting off a part of the pressure surplus when each section is extruded, thereby promoting the improvement of the yield. The products produced by this method have a more uniform and dense structure than the original method. The present invention can reduce the waste loss, improve the yield; shorten the production cycle; and optimize the processing adaptability. DETAILED DESCRIPTION

[0012] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0013] Specific implementation method 1: In this implementation method, a method for forming a small-size 7XXX series aluminum alloy bar blank for bolts is carried out according to the following steps:

[0014] The long cast rod formed by casting is heated after milling, and then rolled into a coil after heating to a set temperature to obtain a coil wire; the coil wire is annealed; the annealed coil wire is drawn by a drawing machine, and then subjected to secondary annealing to complete the forming of 7XXX series aluminum alloy small-size bar blanks for bolts.

[0015] This implementation method innovatively adopts the casting-rolling-drawing method to produce 7XXX series small-size aluminum alloy bar billets for bolts. It can use long cast bars to directly roll coils, and finally draw and cut them to the required specifications. It is expected to solve the above-mentioned difficulties from the root, achieve a significant increase in the yield rate and a significant improvement in production efficiency.

[0016] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the length of the long cast rod formed by casting is 3 to 6 meters. Other aspects are the same as the specific embodiment 1.

[0017] Specific implementation method 3: This implementation method is different from the specific implementation method 1 in that the diameter after milling is 130-150 mm. Other aspects are the same as the specific implementation method 1.

[0018] Specific embodiment 4: This embodiment is different from the specific embodiment 1 in that the heating temperature is 400-450° C. The rest is the same as the specific embodiment 1.

[0019] Specific implementation method 5: This implementation method is different from the specific implementation method 1 in that the diameter after rolling is Φ19.5-21.5 mm. The rest is the same as the specific implementation method 1.

[0020] Specific implementation method 6: This implementation method is different from specific implementation method 5 in that the diameter of the disk is 1300-1500 mm. Other aspects are the same as specific implementation method 5.

[0021] Specific embodiment 7: This embodiment is different from specific embodiment 5 in that the annealing temperature is 399-409°C, kept at this temperature for 2-3 hours, cooled to below 204°C, then heated to 227-237°C, kept at this temperature for 3.5-4.5 hours, and then cooled to room temperature. Others are the same as specific embodiment 5.

[0022] Specific implementation example 8: This implementation example is different from the specific implementation example 1 in that the diameter is reduced by drawing to Φ17.9-18 mm and cut to the actual required length. The rest is the same as the specific implementation example 1.

[0023] Specific embodiment 9: This embodiment is different from specific embodiment 1 in that the secondary annealing treatment temperature is 399-409°C, kept at this temperature for 2-3 hours, cooled to below 204°C, then heated to 227-237°C, kept at this temperature for 3.5-4.5 hours, and then cooled to room temperature. Others are the same as specific embodiment 1.

[0024] The following examples are used to verify the beneficial effects of the present invention:

[0025] Embodiment 1: In this embodiment, a method for forming a 7XXX series aluminum alloy small-size bar blank for bolts is carried out according to the following steps:

[0026] The long cast rod formed by casting is heated after milling, and rolled into a round coil after heating to the set temperature to obtain the round coil wire; the round coil wire is annealed; the annealed round coil wire is drawn by a drawing machine, and then subjected to secondary annealing to complete the forming of the 7XXX series aluminum alloy small-size bar blank for bolts. The length of the long cast rod formed by casting is 3 to 6m. The diameter after milling is 130 to 150mm. The heating temperature is 400 to 450℃. The diameter after rolling is Φ19.5 to 21.5mm. The diameter of the round coil is 1300 to 1500mm. The temperature of the annealing treatment is 399 to 409℃, which is kept for 2 to 3h, cooled to below 204℃, and then heated to 227 to 237℃, kept for 3.5 to 4.5h, and then cooled to room temperature. The diameter is reduced to Φ17.9 to 18mm by drawing, and cut to the actual required length at the same time. The secondary annealing treatment is carried out at a temperature of 399-409° C., kept at that temperature for 2-3 hours, cooled to below 204° C., then heated to 227-237° C., kept at that temperature for 3.5-4.5 hours, and then cooled to room temperature.

[0027] The traditional extrusion method uses a small-sized extruder and needs to cut the long cast rods and extrude them in sections, which will produce a lot of extrusion residues. However, this embodiment uses long cast rods (length of 3 to 6 meters) to directly roll the coils, avoiding the waste of residues caused by frequent cutting of cast rods, allowing more raw materials to be converted into finished products, and significantly improving the yield rate.

[0028] During the entire rolling and drawing process, the material continuity is better. From casting rods to coils and then to final drawing and forming, the processing waste in each step is effectively controlled, which greatly reduces the loss of raw materials compared to the inevitable residual materials after each section of billet extrusion in the extrusion process.

[0029] This method adopts a continuous casting-rolling-drawing process, which saves a lot of intermediate pause time compared to the intermittent operation of loading and unloading billets in sections and frequently adjusting extrusion parameters in the traditional extrusion method. After the long cast bar is milled, it is directly heated and rolled into a round coil, followed by annealing, drawing and secondary annealing. The process connection is compact, and the material does not need to be turned over many times, which greatly speeds up the production rhythm.

[0030] Precisely set parameters such as heating temperature (400-450°C), annealing temperature (399-409°C for 2-3h, cooling and reheating to 227-237°C for 3.5-4.5h) ensure that the material properties of each processing link can quickly reach the ideal state and reduce waiting time. The appropriate heating temperature allows the cast rod to soften quickly to a rollable state, and the appropriate annealing temperature eliminates work hardening in time, making the drawing process smoother, shortening the processing time of a single product as a whole, which in turn greatly shortens the production cycle.

[0031] The rolling process can directly roll the cast rods with a diameter of 130-150mm after milling into a round wire with a diameter of Φ19.5-21.5mm. The diameter of the round wire reaches 1300-1500mm. Compared with extrusion, this gradual deformation processing method is more suitable for the forming of small-sized bar billets. It is not easy to have processing stagnation and repeated debugging due to small billet size and difficult adaptation of the extruder, which ensures efficient and stable production, further helps to shorten the production cycle and improve the yield rate. The drawing process reduces the diameter of the round wire to Φ17.9-18mm and cuts it to the actual required length, accurately forming it, reducing the production of defective products, and consolidating the effect of improving the yield rate.

Claims

1. A method for forming a small-size 7XXX series aluminum alloy bar blank for bolts, characterized in that The forming method of 7XXX series aluminum alloy small-size bar blank for bolts is carried out in the following steps: The long cast rod formed by casting is heated after milling, and then rolled into a coil after heating to a set temperature to obtain a coil wire; the coil wire is annealed; the annealed coil wire is drawn by a drawing machine, and then subjected to secondary annealing to complete the forming of 7XXX series aluminum alloy small-size bar blanks for bolts.

2. The method for forming a 7XXX series aluminum alloy small-size bar blank for bolts according to claim 1, characterized in that The length of the long cast rod formed by casting is 3 to 6 meters.

3. The method for forming a 7XXX series aluminum alloy small-size bar blank for bolts according to claim 1, characterized in that The diameter after milling is 130~150mm.

4. The method for forming a 7XXX series aluminum alloy small-size bar blank for bolts according to claim 1, characterized in that The heating temperature is 400-450°C.

5. The method for forming a 7XXX series aluminum alloy small-size bar blank for bolts according to claim 1, characterized in that The diameter after rolling is Φ19.5~21.5mm.

6. The method for forming a 7XXX series aluminum alloy small-size bar blank for bolts according to claim 5, characterized in that The disc diameter is 1300~1500mm.

7. The method for forming a 7XXX series aluminum alloy small-size bar stock for bolts according to claim 5, characterized in that The annealing treatment temperature is 399-409° C., kept at this temperature for 2-3 hours, cooled to below 204° C., then heated to 227-237° C., kept at this temperature for 3.5-4.5 hours, and then cooled to room temperature.

8. The method for forming a 7XXX series aluminum alloy small-size bar stock for bolts according to claim 1, characterized in that The diameter is reduced by drawing to Φ17.9~18mm and cut to the actual required length.

9. The method for forming a 7XXX series aluminum alloy small-size bar stock for bolts according to claim 1, characterized in that The secondary annealing treatment is carried out at a temperature of 399-409° C., kept at that temperature for 2-3 hours, cooled to below 204° C., then heated to 227-237° C., kept at that temperature for 3.5-4.5 hours, and then cooled to room temperature.