Spinning forming method for thick-wall aluminum alloy cylindrical structure

Abstract

The invention discloses a spinning forming method for a thick-wall aluminum alloy cylindrical structure, belongs to the technical field of material processing, and aims to solve the problems that in the prior art, a thick-wall aluminum alloy component is high in economic cost, the process is complex and difficult to control, and a large-diameter thick-wall part cannot be processed. The spinning forming method is realized by designing a blank, determining a spinning pass and a thinning rate, debugging spinning equipment and installing the blank, performing for the first pass of thermal strong spinning, performing for the second pass of thermal strong spinning, and machining. The technical problems that the wall thickness reduction rate of a large thick-wall conical structure is large, forming is difficult, hot spinning forming precision is difficult to control, and annealing deformation is large are solved. The large-diameter thick-wall part can be machined, the manufacturing cost is saved, and manpower and material resource consumption is reduced. And meanwhile, the defects of high raw material consumption, unstable product mechanical property and the like are overcome, and the problems of unstable product quality and the like in the production process are fundamentally avoided.

Description

Technical Field

[0001] This article relates to a spinning forming method for thick-walled aluminum alloy cylindrical structures, specifically to an aluminum alloy spinning processing method, belonging to the field of material processing technology. Background Art

[0002] Existing forming processes for thick-walled aluminum alloy cylindrical structures include multi-directional forging and backward extrusion forming. Among them, the equipment used for multi-directional forging and backward extrusion is a hydraulic forging machine. There are many passes in multi-directional forging, and new molds need to be replaced during the process. The repeat positioning accuracy is poor, which affects the quality of workpieces. After backward extrusion forming, the quenching and annealing processes are complex and difficult to control. The existing processes can only be used for small thin-walled parts, and it is very difficult for large-diameter thick-walled parts. Moreover, the economic cost is relatively high.

[0003] As early as in the 19th century, people began to use the method of manual spinning to process various soft metal utensils. A metal sheet or cylindrical blank is fixed to the tail of the spinning machine mold with a mandrel and rotates together with the main shaft. Then, the spinning wheel starts to extrude the blank from the end, causing the blank to continuously undergo plastic deformation point by point. Finally, a processing technology that forms all into a hollow part is spinning. With the further development of related technologies, spinning equipment emerged, changing from traditional manual to electric production. And with the wide application of metals such as copper and aluminum in spinning production, it further meets the social demand for spun parts. At present, the well-known spinning materials have exceeded two hundred kinds. After being classified according to non-ferrous metals and ferrous metals respectively, each accounts for 50%. Metal spinning forming is a new processing technology in metal pressure processing in recent years. This technology combines key production processes such as traditional forging, extrusion, and stretching, and is a production process with less or no cutting. Compared with traditional technologies, the spinning forming tool has obvious advantages and has been widely used in future social production. And in current industries such as aerospace, the demand for metal spinning forming technology is very high, so it has received the attention of relevant personnel.

[0004] In the prior art, the conventional forming methods for thick-walled cylindrical parts are complex in operation, difficult to form, and poor in product uniformity. In current metal spinning processing, metals such as aluminum, copper, and titanium are the most common. Most of these metals are spun at room temperature, and their ultimate thinning rate is about 70%-90%. Therefore, the plastic deformation effect of spinning is ideal. Spinning processing technology is a relatively advanced plastic processing method. It combines the process characteristics of forging, extrusion, rolling, stretching, bending, leveling, etc., and is the main processing method for plastic forming of rotary parts. When spinning, the spinning wheel and the blank are in a point contact state, and metals with high strength, complexity, and difficult deformation can also be easily formed, which can greatly reduce processing costs and energy consumption. Spinning technology has the advantages of simple processes, high product dimensional accuracy, high material utilization rate, non-cutting, easy operation, easy assembly, etc., and is widely used in the fields of aviation, aerospace, military, and civilian products. Spinning has become the main method for precision plastic forming, which can solve the problem of processing large-diameter thick-walled parts, save manufacturing costs, and reduce the consumption of human and material resources. Summary of the Invention

[0005] In order to achieve the above objectives and solve the problems existing in the current technology, such as the appearance of pores, cracks, slag inclusions on the workpiece, complex and uncontrollable processes, and the inability to process large-diameter thick-walled parts, save manufacturing costs, and reduce the consumption of human and material resources, a spinning forming method for a thick-walled aluminum alloy cylindrical structure of the present invention includes the following steps: Step 1: Determine the blank thickness. The blank thickness affects the spinning force and the number of spinning passes. Calculate the blank thickness according to the formula. The selected blank is a circular plate. Set two positioning holes at the center of the blank for positioning and matching with the spinning die. Perform surface treatment and annealing treatment on the blank to obtain the treated blank.

[0006] Step 2: Determine the number of spinning passes and the thinning rate. Determine the number of spinning passes and the thinning rate of the blank according to the cross-sectional shrinkage rate of the material. The cross-sectional shrinkage rate of the aluminum alloy material is 15-40%, and the maximum wall thickness thinning rate is 50-70%. The wall thickness thinning rate of the first-pass preforming is 30%, and the semi-cone angle is 45°. Select a spinning wheel with R30. Determine the number of spinning passes by the thinning rate, and at the same time, calculate the final number of spinning passes according to the spinning process characteristics of the selected spinning wheel.

[0007] Step 3: Debug the spinning equipment and clamp the blank. Select a CNC horizontal spinning machine to install the die. Align and position the blank with the center hole at the top of the die. After the die and the blank are installed, perform the first hot spinning pass to obtain a preformed blank. During the hot spinning process, first preheat the blank and the die. Heat the die to 150°C and the blank to above 250°C before starting the hot spinning. During the first pass, use a spray gun to locally and continuously heat the deformed area during the spinning process to keep the blank temperature above 300°C.

[0008] Step 4: The second hot spinning pass; the workpiece obtained from the first pass is subjected to a second hot spinning using a numerically controlled horizontal spinning machine, and the heating temperature is within the same range as that selected for the first pass; the wall thickness reduction rate at the end of the second pass is 15%, and the radius of the spinning wheel fillet is selected as R30.

[0009] Step 5: Machining; the workpiece from Step 4 is machined.

[0010] The surface treatment and annealing treatment of the blank mentioned in Step 1 are specifically as follows: grind the surface of the blank until there are no cracks, scratches, etc. on the outer surface.

[0011] The ground blank is annealed. The blank is heated to 380 ± 5 °C in a trolley furnace and held for 3 h.

[0012] After the spinning die is installed in Step 3, use a dial indicator to check the runout of the spinning die and make the runout value of the conical surface less than or equal to 0.1 mm.

[0013] During the first pass spinning process in Step 3, the spindle speed of the numerically controlled horizontal spinning machine is 20 r / min, the feed rate is 20 mm / min, and the spinning gap is 45 ± 0.1 mm.

[0014] During the second pass spinning process in Step 4, the spindle speed of the numerically controlled horizontal spinning machine is 20 r / min, the feed is 25 mm / min, and the spinning gap is 35 ± 0.1 mm.

[0015] The beneficial effects of the present invention are as follows: A spinning forming method for a thick-walled aluminum alloy cylindrical structure of the present invention solves the problems of large wall thickness reduction rate and difficult forming of a conical cylindrical structure, and difficult precision control of hot spinning forming. By using a hot spinning forming device and an optimized spinning process, two-pass thick-walled hot spinning forming of a thick-walled aluminum alloy cylindrical structure is realized. Compared with the previous forming process methods such as backward extrusion and multi-directional forging for such components, this method greatly saves the mold manufacturing cost and shortens the product processing cycle. It has accumulated valuable experience for the forming of large-diameter thick-walled material structures and laid a foundation for accelerating the realization of engineering applications. Brief Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the circular plate blank structure of a spinning forming method for a thick-walled aluminum alloy cylindrical structure of the present invention; Figure 2 It is a schematic diagram after the first pass pre-forming in a spinning forming method for a thick-walled aluminum alloy cylindrical structure of the present invention; Figure 3 It is a schematic diagram after the final forming in a spinning forming method for a thick-walled aluminum alloy cylindrical structure of the present invention. Detailed Embodiments

[0017] The embodiments of the present invention will be further described below with reference to the drawings.

[0018] Example 1 A spinning forming method for a thick-walled aluminum alloy cylindrical structure of the present invention includes the following steps: Step 1: Prepare the blank. Refer to Figure 1 . The blank is a circular plate-shaped blank with a diameter of φ1000mm and a thickness of 60mm. A positioning hole for positioning and fitting with the spinning die is reserved at the center of the blank. The surface of the blank is treated and annealed to obtain a treated blank.

[0019] Step 2: Determine the spinning passes and thinning rate. Determine the spinning passes and thinning rate of the blank according to the cross-sectional shrinkage rate of the material. The cross-sectional shrinkage rate of the aluminum alloy material is 15-40%, and the maximum wall thickness thinning rate is 50-70%. The wall thickness thinning rate of the first-pass preforming is 30%, the semi-cone angle is 45°, and a spinning wheel with R30 is selected. Determine the spinning passes by the thinning rate. At the same time, based on the spinning process characteristics of the selected spinning wheel, calculate that the final spinning passes are two passes.

[0020] Step 3: Debug the spinning equipment and clamp the blank. Select a CNC horizontal spinning machine to install the die, and position the blank in cooperation with the central hole at the top of the die. After the die and the blank are installed; Obtain a preformed blank by hot spinning the first pass. During the hot spinning process, first preheat the blank and the die. The die is heated to 150°C and the blank is heated to above 250°C before starting hot spinning. During the first pass, use a spray gun to locally and continuously heat the deformed area during the spinning process to keep the temperature of the blank above 300°C. The large-end diameter of the workpiece in the first pass is 1000mm, the small-end diameter is 300mm, and the height of the workpiece is greater than 480mm; Refer to Figure 2 .

[0021] Step 4: Hot spin the second pass; Use a CNC horizontal spinning machine to perform a second hot spinning on the workpiece obtained in the first pass. The heating temperature is within the same range as the heating temperature selected in the first pass; The wall thickness thinning rate of the final forming in the second pass is 15%. To prevent the material at the front edge of the spinning wheel from bulging too high locally, the spinning wheel fillet radius is selected as R30. The workpiece obtained in the second pass is shown in Figure 3 . Step 5: Machining; Machine the workpiece in Step 4.

[0022] The surface treatment and annealing treatment of the blank mentioned in Step 1 are specifically as follows: Grind the surface of the blank until there are no cracks, scratches, etc. on the surface.

[0023] Anneal the ground blank. The blank is heated to 380±5°C in a trolley furnace and held for 3h.

[0024] After the spinning die is installed in Step 3, use a dial indicator to check the runout of the spinning die and make the runout value of its conical surface less than or equal to 0.1 mm.

[0025] In the first-pass spinning process of Step 3, the spindle speed of the CNC horizontal spinning machine is 20 r / min, the feed rate is 20 mm / min, and the spinning gap is 45 ± 0.1 mm.

[0026] In the second-pass spinning process of Step 4, the spindle speed of the CNC horizontal spinning machine is 20 r / min, the feed is 25 mm / min, and the spinning gap is 35 ± 0.1 mm.

Claims

1. A spinning forming method for a thick-walled aluminum alloy cylindrical structure, characterized in that, It includes the following steps: Step 1: Determine the blank thickness. The blank thickness affects the spinning pressure and the number of spinning passes. Calculate the blank thickness according to the formula. The selected blank is a circular sheet. Set two positioning holes that are positioned and matched with the spinning die at the center of the blank. Perform surface treatment and annealing treatment on the blank to obtain the treated blank; Step 2: Determine the number of spinning passes and the reduction rate. Determine the number of spinning passes and the reduction rate of the blank according to the cross-sectional shrinkage rate of the material. The cross-sectional shrinkage rate of the aluminum alloy material is 15 - 40%, and the maximum wall thickness reduction rate is 50 - 70%. The wall thickness reduction rate of the preforming in one pass is 30%, and the semi-cone angle is 30°. Select a spinning wheel with R30; Determine the number of spinning passes by the reduction rate, and at the same time, calculate the final number of spinning passes based on the spinning process characteristics of the selected spinning wheel; Step 3: Debug the spinning equipment and clamp the blank. Select a CNC horizontal spinning machine to install the die. Position and match the blank with the center hole at the top of the die. After the die and the blank are installed; Obtain the preformed blank through hot spinning in the first pass. During the hot spinning process, preheat the blank and the die first. Start hot spinning when the die is heated to 150°C and the blank is heated to above 250°C. During the first pass, use a spray gun to locally and continuously heat the deformed area during the spinning process to keep the blank temperature above 300°C; Step 4: Hot spin the second pass; Use a CNC horizontal spinning machine to perform the second hot spinning on the workpiece obtained in the first pass. The heating temperature range is the same as that selected in the first pass; The wall thickness reduction rate of the final forming in the second pass is 15%, and the fillet radius of the spinning wheel is selected as R30; Step 5: Machining; Machine the workpiece in Step 4.

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