A precision turning method for hard aluminum alloy thin-walled housing parts
By optimizing the heat treatment and turning process, combined with special tooling design, the cutting flutter and assembly difficulties of hard aluminum alloy thin-walled shell parts during the processing process are solved, achieving high-precision and efficient processing effects.
Patent Information
- Application Number
- CN202311035613.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-17
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2043-08-17
AI Technical Summary
During the processing process, hard aluminum alloy thin-walled shell parts have problems such as cutting vibration, cutting phenomenon, difficulty in loading and processing accuracy, especially in applications in the aerospace field, existing methods such as casting paraffin or low-melting alloys have limitations such as cumbersome processes and long-term time.
By optimizing heat treatment processes such as forging, annealing, and solid solution treatment, combined with reasonable turning technology methods, including loading methods, processing parameters and cutting path planning, special tooling is designed, the process parameters and retained volume of rough-cut, semi-finishing and precision-cutting processes are optimized, and artificial aging and natural aging treatment are interspersed to solve the problem of difficult loading and clamping of workpieces, improving rigidity, reducing cutting flutter and cutting tooling.
The effective control wall thickness error is within 0.05mm, the maximum ellipticity of the open end of the part is less than 0.2mm, and the surface roughness is less than Ra1.6, which meets the technical indicators of hard aluminum alloy thin-walled shell parts and improves processing efficiency and accuracy.
Smart Images
Figure CN116787084B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of precision machinery manufacturing, and particularly relates to a precision turning method for hard aluminum alloy thin-walled cover parts. Background Art
[0002] Hard aluminum alloy thin-walled cover parts are widely used in the aerospace field, mainly as dust covers, sealing covers, fairings, etc. for various important instruments. The wall thickness of such parts is usually relatively thin (1 mm - 2 mm). To balance the strength of the parts, heat treatment is generally required to improve the mechanical properties of the parts. However, the thin-walled structure reduces the rigidity of the parts, and heat treatment significantly increases the hardness of the material, thereby greatly increasing the processing difficulty of such parts. On the one hand, the wall thickness of the parts is thin and the material hardness is high, so cutting chatter and tool deflection are likely to occur during the finish machining stage, resulting in poor surface quality of the parts, serious deformation, and large equal-thickness errors at the thin-walled parts. On the other hand, most of the structures of such parts are cylindrical or spherical shell-shaped with one end closed and one end open, making positioning and clamping difficult. If the clamping method is not properly selected, the clamping stress will cause clamping deformation of the parts, affecting the machining accuracy of the parts.
[0003] To ensure the machining accuracy and quality of such parts, the method of pouring paraffin or low-melting alloy is mostly used to increase the rigidity of such parts, or the method of wrapping soft rubber is used to reduce cutting chatter. However, both of these methods have certain limitations, such as cumbersome processes, long time consumption, low processing efficiency, etc., and are less used in mass production machining. Summary of the Invention
[0004] In order to solve the above problems, the present invention provides a precision turning process method for hard aluminum alloy thin-walled cover parts. The aim is to make the internal stress of the hard aluminum alloy thin-walled cover parts evenly distributed through an optimized heat treatment process, and at the same time reduce the surface residual stress caused by mechanical cold processing; and through an optimized turning process method, including clamping methods, machining parameters, cutting path planning, etc., to ensure the machining quality and efficiency of the hard aluminum alloy thin-walled cover parts.
[0005] To achieve the above object, the technical solution proposed by the present invention is as follows:
[0006] A precision turning method for hard aluminum alloy thin-walled cover parts, the method comprising the following steps:
[0007] Step S1, blank forging: According to the volume of the part blank, the raw material is cut into an appropriate length for forging. The number of forging times is not less than 3 times, and flaw detection is carried out before and after forging;
[0008] Step S2, Annealing of the forging: Place the forged blank flat in an air furnace for annealing. The blanks are not stacked to prevent uneven heating rates of the blanks, which may lead to insufficient release of internal forging stresses.
[0009] Step S3, Rough turning of the outer shape: Draw a rough turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled housing parts. Leave a uniform allowance of 3 - 4 mm at each contour feature of the part according to the dimensions marked on the engineering drawing. Reserve a process flange with an appropriate thickness on the outside of the open end of the part, reserve a solid process boss on the inside of the closed end of the part, and reserve a solid process chuck on the outside of the closed end of the part. Then rough turn the contour features of the inner hole and outer circle of the part according to the rough turning process sketch.
[0010] Step S4, Solution treatment: Perform solution treatment on the rough-turned hard aluminum alloy thin-walled housing parts, that is, quenching treatment plus artificial aging, and detect the hardness and conductivity.
[0011] Step S5, First semi-finish turning: Draw a first semi-finish turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled housing parts. Leave a uniform allowance of 1 mm at each contour feature of the part according to the dimensions marked on the engineering drawing. Retain the process flange and the solid process boss, and remove the solid process chuck. Then semi-finish turn the contour features of each part of the part in the order of inner hole first and then outer circle according to the first semi-finish turning process sketch.
[0012] Step S6, Artificial aging: Place the hard aluminum alloy thin-walled housing parts after the first semi-finish turning flat with the open end up in an air furnace for artificial aging treatment.
[0013] Step S7, Second semi-finish turning: Draw a second semi-finish turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled housing parts. Leave a uniform allowance of 0.5 mm at each contour feature of the part according to the dimensions marked on the engineering drawing. Retain the solid process boss and remove the process flange. Then semi-finish turn the contour features of the inner hole of the part and the solid process boss with the help of the first special tooling, and drill and tap an M8 flat-bottom thread hole on the solid process boss, with the depth less than the height of the solid process boss. Finally, semi-finish turn the contour features of the outer circle of the part with the second special tooling and remove the process flange.
[0014] Step S8, Artificial aging: Place the hard aluminum alloy thin-walled housing parts after the second semi-finish turning flat with the open end up in an air furnace for artificial aging treatment.
[0015] Step S9, Finish turning: According to the engineering drawing of the hard aluminum alloy thin-walled housing parts, use the second special tooling and the third special tooling to clamp and align the hard aluminum alloy thin-walled housing parts, and successively finish turning the contour features of the outer circle and inner hole of the hard aluminum alloy thin-walled housing parts to all meet the requirements of the drawing dimensions, and remove the solid process boss.
[0016] Step S10, natural aging: Place the precision-turned hard aluminum alloy thin-walled housing parts with the open end facing up flat on a marble platform for natural aging treatment, and then send them for fine inspection.
[0017] Further, in the step S2, the annealing temperature is 360°C ± 5°C, the holding time is 3 - 4 hours, cool in the furnace to below 260°C, and then air-cool to room temperature. It is required that the temperature gradient during heating and cooling is not greater than 30°C / h.
[0018] Further, in the step S3, the rough turning tool is a conventional aluminum alloy turning tool with a shape of 80° or 55°. The cutting speed is not greater than 260 m / min, the cutting depth is 0.3 - 0.5 mm, and the feed rate is 32 - 38 mm / min. Flushing emulsion or cutting fluid during rough turning.
[0019] Further, in the step S3, the blank is rough-turned in three working steps according to the rough turning process diagram: First, turn the blank into a regular cylinder, then rough-turn the solid process chuck and the outer contour features of the part, and finally clamp the outer circle of the part or the solid process chuck and align it, and rough-turn the process flange and the inner hole contour features.
[0020] Further, in the step S4, the quenching temperature is 495°C - 505°C, hold in an air furnace for 210 - 360 min, water-cool at 20°C - 60°C, and the transfer time of the part from the air furnace to the water tank does not exceed 20 seconds; then perform artificial aging on the part cooled to room temperature, the aging temperature is 185°C - 195°C, and the holding time is 8 - 12 hours. The time interval between quenching and artificial aging is less than 3 hours; the part is placed upright or inclined in the air furnace, and the water entry speed should be fast to prevent uneven distribution of quenching stress caused by uneven contact between the part and cold water.
[0021] Further, in the step S5, the tool is a special aluminum alloy turning tool with a shape of 55°. The cutting speed is not greater than 230 m / min, the cutting depth is 0.1 - 0.3 mm, and the feed rate is 20 - 30 mm / min. Flushing emulsion or cutting fluid during turning, and observe the tool wear condition in real time and replace the tool in time.
[0022] Further, in the step S5, after the first semi-finishing turning process is completed, the process flange is milled into a fan-shaped petal shape, and 8 groups of process threaded through holes are drilled and tapped at the corresponding positions on the end face of the process flange, aiming to weaken the hindrance of the integral circular process flange to the release of internal stress of the part during artificial aging in step S6, and at the same time facilitate the cooperation of the part with the first special fixture in the second semi-finishing turning process in step S7 to realize the end face positioning and clamping of the part.
[0023] Further, in the artificial aging of step S6 and step S8, an air furnace is used as the artificial aging equipment, the holding temperature is 190°C ± 20°C, the holding time is 6 - 8 hours, and the workpiece is taken out after being cooled in the furnace to room temperature. It is required that the temperature gradient of heating and cooling does not exceed 30°C / h.
[0024] Further, in step S7, the tool for the second semi-finishing turning is a special aluminum alloy turning tool with a shape of 55°. The cutting speed does not exceed 180 m / min, the cutting depth is 0.05 - 0.1 mm, the feed rate is 10 - 20 mm / min, and the emulsifying fluid or cutting fluid is flushed during the turning process. The tool wear condition is observed in real time and the tool is replaced in time.
[0025] Further, in step S7, the first special fixture in the second semi-finishing turning process is of a revolving body structure, including a first special fixture solid chuck, a concave cavity, a square process hole and a screw through hole. The first special fixture solid chuck and the concave cavity are located at both ends of the first special fixture and are coaxial. The first special fixture solid chuck is used to connect with the machine tool three-jaw chuck, the concave cavity is used to accommodate the workpiece to be processed, and there is a certain gap between the concave cavity and the workpiece to be processed. There are 8 evenly distributed square process holes on the circumference of the first special fixture, and 8 evenly distributed screw through holes are drilled on the upper end face of the first special fixture, located at the center of the square process hole, and the screw through holes are communicated with the square process holes.
[0026] Further, the second special fixture in step S7 and step S9 is of a revolving body structure, including a second special fixture solid chuck, a positioning stop, a spacer adapter, a spacer, a reverse pull stud and a locking screw. The second special fixture solid chuck, the positioning stop, the spacer adapter, the spacer and the reverse pull stud are coaxial. The second special fixture solid chuck is used to connect with the machine tool three-jaw chuck, the positioning stop is used to cooperate with the inner hole of the workpiece, and the cooperation gap is between 0.1 - 0.2 mm. The spacer adapter and the spacer are connected by a locking screw. The outer end face of the spacer fits with the plane at the center of the inner side of the workpiece, and the reverse pull stud is connected with the flat bottom threaded hole on the solid process boss to realize the positioning and clamping of the hard aluminum alloy thin-walled cover parts.
[0027] Further, in the step S9, the third special tooling in the finish turning process is of a rotary body structure, including a third special tooling solid chuck, an air pipe adapter interface, a process through hole, a workpiece positioning concave cavity, a sealing groove, and an air passage; the third special tooling solid chuck, the air pipe adapter interface, the workpiece positioning concave cavity, and the sealing groove are coaxial; the third special tooling solid chuck is connected to the three-jaw chuck of the machine tool; the air pipe adapter interface is connected to an air pipe adapter, and the air pipe adapter is connected to a vacuum pump through a hose; the process through hole is located on the outer circumference of the third special tooling, facilitating alignment during workpiece clamping and exhausting when the workpiece is taken out; the workpiece positioning concave cavity is used to accommodate the workpiece and can completely fit with the arc surface of the closed end of the workpiece, with a certain gap in the circumferential direction, filled with butter or vacuum grease; a soft elastic sealing ring is installed in the sealing groove; the air passage is connected to the air pipe adapter interface in a cross shape.
[0028] Further, in the step S10, the natural aging treatment time is 96 hours.
[0029] The present invention has the following beneficial effects: The precision turning method for hard aluminum alloy thin-walled cover shell parts provided by the present invention first arranges the process parameters of forging, annealing, and solution treatment reasonably, so that the internal stress of the blank of the hard aluminum alloy thin-walled cover shell parts is evenly distributed, increasing the isotropy of the material and the uniformity of the internal structure; then, by reasonably designing the process diagrams, process parameters, and allowances of rough turning, semi-finish turning, and finish turning processes, and interspersing artificial aging and natural aging treatments, the residual stress caused by cutting processing is fully released, greatly reducing the influence of surface residual stress on part deformation; finally, according to the processing characteristics of different turning processes and the structural strength of the workpiece, corresponding process features (process flanges, solid process chucks, solid process bosses, flat-bottom process threaded holes, etc.) and special toolings are designed, solving the problem of difficult workpiece clamping while improving the rigidity of the workpiece, reducing the influence of cutting chatter and tool deflection phenomena in semi-finish turning and finish turning processes on the surface quality and deformation of the parts, improving the wall thickness uniformity of the hard aluminum alloy thin-walled cover shell parts, and effectively ensuring the processing efficiency and processing accuracy of the hard aluminum alloy thin-walled cover shell parts. Practice has proved that for the parts processed by using the precision turning process method for hard aluminum alloy thin-walled cover shell parts provided by the present invention, after inspection, the equal thickness error of the wall thickness is effectively controlled within 0.05 mm, the maximum ovality of the open end of the part is less than 0.2 mm, and the surface roughness is less than Ra1.6, fully meeting the technical index requirements of the hard aluminum alloy thin-walled cover shell parts. Description of the Drawings
[0030] Figure 1 It is a schematic structural diagram of the hard aluminum alloy thin-walled cover shell parts of the present invention;
[0031] Figure 2Schematic diagram of the rough turning process of the present invention;
[0032] Figure 3 Schematic diagram of the first semi-finishing turning process of the present invention;
[0033] Figure 4 Schematic diagram of the second semi-finishing turning process of the present invention;
[0034] Figure 5 Schematic diagram of the structure of the first special tooling of the present invention;
[0035] Figure 6 Schematic diagram of the structure of the second special tooling of the present invention;
[0036] Figure 7 Schematic diagram of the structure of the third special tooling of the present invention;
[0037] Each label in the figure represents: 2-1 process flange, 2-2 solid process boss, 2-3 solid process chuck; 3-1 sector petal process flange, 3-2 process threaded through-hole; 4-1 M8 flat-bottom threaded hole; 5-1 solid chuck of the first special tooling, 5-2 main body of the first special tooling, 5-3 screw through-hole, 5-4 square process hole, 5-5 concave cavity; 6-1 solid chuck of the second special tooling, 6-2 positioning stop, 6-3 spacer adapter, 6-4 spacer, 6-5 reverse pull stud, 6-6 locking screw; 7-1 solid chuck of the third special tooling, 7-2 air pipe adapter interface, 7-3 process through-hole, 7-4 workpiece positioning concave cavity, 7-5 sealing groove, 7-6 air channel. Detailed implementation manners
[0038] The following describes the detailed implementation manners of the present invention with reference to the accompanying drawings.
[0039] As Figure 1-7As shown in the figure, taking the precision turning of hard aluminum alloy thin-walled cover parts as an example, it is described as a specific embodiment of the present invention. The material of the hard aluminum alloy thin-walled cover parts is forged 2A14, and the final state of the parts is required to be T6 CZ state, with a Brinell hardness greater than 110HBS. The maximum diameter of the parts is Φ260mm, the wall thickness is 1mm, the closed end of the parts is arc-shaped, and the geometric tolerance grade is implemented according to the national standard GB / T1184-k level, that is, the geometric accuracy of the parts should be less than ±0.2mm. The hard aluminum alloy thin-walled cover parts have a thin wall thickness and high material hardness. In the finish machining stage, cutting chatter and tool deflection are likely to occur, affecting the surface quality of the parts and making it difficult to guarantee the geometric accuracy of the parts. In terms of structure, one end of the hard aluminum alloy thin-walled cover parts is a closed free-form surface, and the other end is a thin-walled structure with a long overhang. During the machining process, there are problems such as serious clamping deformation and difficulties in positioning and alignment. To solve the above problems and ensure the machining accuracy, machining efficiency, and machining quality of the hard aluminum alloy thin-walled cover parts, through a large number of tests and summaries, a precision turning method for such hard aluminum alloy thin-walled cover parts is proposed, which specifically includes the following steps:
[0040] S1 Blank forging: According to the volume of the part blank, cut the hard aluminum alloy bar into an appropriate length for forging, requiring at least 3 forging times, and perform flaw detection before and after forging;
[0041] S2 Forged part annealing: Place the forged blank flat in an air furnace for annealing, noting that stacking is not allowed to prevent uneven heating rates of the blank parts and insufficient release of internal forging stresses;
[0042] S3 Rough turning of the outer shape: Draw a rough turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled cover parts, evenly leave a margin of 3-4mm at each contour feature of the part according to the dimensions marked on the engineering drawing, and reserve a process flange 2-1 with an appropriate thickness outside the open end of the part, a solid process boss 2-2 inside the closed end of the part, and a solid process chuck 2-3 outside the closed end of the part; then rough turn the contour features of the inner hole and outer circle of the part according to the rough turning process sketch;
[0043] S4 Solution treatment: Perform solution treatment on the hard aluminum alloy thin-walled cover parts after rough turning, that is, quenching treatment plus artificial aging, and detect the hardness and conductivity of the hard aluminum alloy thin-walled cover parts;
[0044] S5 First semi-finish turning: Draw a first semi-finish turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled cover parts, evenly leave a margin of 1mm at each contour feature of the part according to the dimensions marked on the engineering drawing, retain the process flange 2-1 and the solid process boss 2-2, and remove the solid process chuck 2-3; then semi-finish turn the contour features of the part in the order of inner hole first and then outer circle according to the first semi-finish turning process sketch;
[0045] S6 Artificial aging: Place the open end of the hard aluminum alloy thin-walled cover part after the first semi-finishing turning facing upward and flat in an air furnace for artificial aging treatment;
[0046] S7 Second semi-finishing turning: Draw a second semi-finishing turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled cover part. Leave a uniform allowance of 0.5 mm at each contour feature of the part according to the dimensions marked on the engineering drawing, retain the solid process boss 2-2, and remove the process flange 2-1; then use the first special tooling to semi-finish turn the contour features of each part of the inner hole of the part and the solid process boss 2-2, and drill and tap an M8 flat-bottom threaded hole 4-1 on the solid process boss 2-2, with the depth less than the height of the solid process boss 2-2; finally, use the second special tooling to semi-finish turn the contour features of each part of the outer circle of the part and remove the process flange 2-1;
[0047] S8 Artificial aging: Place the open end of the hard aluminum alloy thin-walled cover part after the second semi-finishing turning facing upward and flat in an air furnace for artificial aging treatment;
[0048] S9 Finish turning: According to the engineering drawing of the hard aluminum alloy thin-walled cover part, use the second special tooling and the third special tooling to clamp and align the hard aluminum alloy thin-walled cover part, and successively finish turn the contour features of each part of the outer circle and the inner hole of the hard aluminum alloy thin-walled cover part to all meet the requirements of the drawing dimensions, and remove the solid process boss 2-2;
[0049] S10 Natural aging: Place the open end of the hard aluminum alloy thin-walled cover part after finish turning facing upward and flat on a marble platform, conduct natural aging treatment for 96 hours, and then send it for fine inspection.
[0050] Further, in the annealing of the S2 forging, the annealing temperature is 360°C ± 5°C, the holding time is 3 - 4 hours, cool it in the furnace to below 260°C, and take it out of the furnace and air-cool it to room temperature. It is required that the temperature gradient during heating and cooling is not greater than 30°C / h.
[0051] Further, in the S3 rough turning of the outer shape process, the rough turning tool is a conventional aluminum alloy turning tool with a shape of 80° or 55°. The cutting speed is not greater than 260 m / min, the cutting depth is 0.3 - 0.5 mm, and the feed speed is 32 - 38 mm / min. Flush the emulsion or cutting fluid during rough turning;
[0052] Further, in the S3 rough turning of the outer shape process, the rough turning of the blank part is carried out in three working steps according to the rough turning process sketch: First, turn the blank part into a regular cylinder, then rough turn the solid process chuck 2-3 and the outer circle contour feature of the part, and finally clamp the outer circle of the part or the solid process chuck 2-3 and align it, and rough turn the process flange 2-1 and the inner hole contour feature;
[0053] Furthermore, in the S4 solution treatment, the quenching temperature is 495°C to 505°C, holding for 210 to 360 minutes in an air furnace, water cooling at 20°C to 60°C, and the transfer time of the part from the air furnace to the water tank does not exceed 20 seconds; then artificial aging is carried out on the part cooled to room temperature, the aging temperature is 185°C to 195°C, and the holding time is 8 to 12 hours. The time interval between quenching and artificial aging is less than 3 hours; the parts are placed upright or inclined in the air furnace, and the water entry speed should be fast to prevent uneven distribution of quenching stress caused by uneven contact between the parts and cold water.
[0054] Furthermore, in the S5 first semi-finishing turning process, a special turning tool for aluminum alloy with a shape of 55° is selected, the cutting speed is not greater than 230 m / min, the cutting depth is 0.1 to 0.3 mm, the feed rate is 20 to 30 mm / min, and emulsion or cutting fluid is flushed during turning. Observe the tool wear condition in real time and replace the tool in time;
[0055] Furthermore, after the S5 first semi-finishing turning process is completed, the process flange 2-1 is numerically controlled milled into a fan-shaped petal process flange 3-1, and 8 groups of process threaded through holes 3-2 are drilled and tapped at the corresponding positions on the end face of the process flange, aiming to weaken the hindrance of the integral circular process flange 2-1 to the internal stress release of the part during the S6 artificial aging, and at the same time facilitate the cooperation between the part and the special tooling 1 in the S7 second semi-finishing turning process to realize the end face positioning and clamping of the part.
[0056] Furthermore, for the S6 artificial aging and S8 artificial aging, an air furnace is selected as the equipment, the holding temperature is 190°C, the holding time is 6 to 8 hours, and the workpiece is taken out after being cooled to room temperature with the furnace. It is required that the temperature gradient of heating and cooling does not exceed 30°C / h.
[0057] Furthermore, in the S7 second semi-finishing turning process, a special turning tool for aluminum alloy with a shape of 55° is selected, the cutting speed is not greater than 180 m / min, the cutting depth is 0.05 to 0.1 mm, the feed rate is 10 to 20 mm / min, and emulsion or cutting fluid is flushed during turning. Observe the tool wear condition in real time and replace the tool in time;
[0058] Furthermore, the first special tooling in the second semi-finishing turning process of S7 is of a revolving body structure, including structures such as a first special tooling solid chuck 5-1, a concave cavity 5-5, a square process hole 5-4, and screw through holes 5-3. The first special tooling solid chuck 5-1 and the concave cavity 5-5 are located at both ends of the first special tooling and are coaxial. The first special tooling solid chuck 5-1 is used to connect with the machine tool three-jaw chuck, and the concave cavity 5-5 is used to accommodate the workpiece to be machined, and there is a certain gap between the concave cavity 5-5 and the workpiece to be machined. There are 8 evenly distributed square process holes 5-4 on the circumference of the first special tooling, and 8 evenly distributed screw through holes 5-3 are drilled on the upper end face of the first special tooling, located at the center of the square process hole 5-4, and the screw through holes 5-3 are communicated with the square process holes 5-4.
[0059] Furthermore, the second special tooling in the second semi-finishing turning process of S7 and the finishing turning process of S9 is of a revolving body structure, including structures such as a second special tooling solid chuck 6-1, a positioning stop 6-2, a pad adapter 6-3, a pad 6-4, a reverse pull stud 6-5, and a locking screw 6-6. The second special tooling solid chuck 6-1, the positioning stop 6-2, the pad adapter 6-3, the pad 6-4, and the reverse pull stud 6-5 are coaxial. The second special tooling solid chuck 6-1 is used to connect with the machine tool three-jaw chuck. The positioning stop 6-2 is used to cooperate with the inner hole of the workpiece, and the cooperation gap is between 0.1 and 0.2 mm. The pad adapter 6-3 and the pad 6-4 are connected by a locking screw 6-6. The outer end face of the pad 6-4 is fitted with the plane at the center of the inner side of the workpiece. The reverse pull stud 6-5 is connected with the M8 flat bottom threaded hole 4-1 on the solid process boss 2-2 to realize the positioning and clamping of the hard aluminum alloy thin-walled cover parts.
[0060] Furthermore, the third special tooling in the S9 finish turning process is of a revolving body structure, including structural features such as a solid chuck 7-1 of the third special tooling, an air pipe adapter interface 7-2, a process through hole 7-3, a workpiece positioning concave cavity 7-4, a sealing groove 7-5, an air passage 7-6, etc. The solid chuck 7-1 of the third special tooling, the air pipe adapter interface 7-2, the workpiece positioning concave cavity 7-4, and the sealing groove 7-5 are coaxial. The solid chuck 7-1 of the third special tooling is connected to the three-jaw chuck of the machine tool. The air pipe adapter interface 7-2 is connected to an air pipe adapter, and the air pipe adapter is connected to a vacuum pump through a hose. The process through hole 7-3 is located on the outer circumference of the special tooling, facilitating alignment during workpiece clamping and exhausting when the workpiece is removed. The workpiece positioning concave cavity 7-4 is used to accommodate the workpiece and can completely fit with the arc surface of the closed end of the workpiece, with a certain gap in the circumferential direction, filled with butter or vacuum grease. A soft elastic sealing ring is installed in the sealing groove 7-5. The air passage 7-6 is connected to the air pipe adapter interface in a cross shape.
[0061] The parts not elaborated in detail in the present invention belong to the well-known technologies in the art.
[0062] The specific embodiments described above are only the preferred embodiments of the present invention, rather than an exhaustive list of the feasible embodiments of the present invention. For those of ordinary skill in the art, any obvious modifications made without departing from the principles and spirit of the present invention should be considered to be included within the protection scope of the claims of the present invention.
Claims
1. A precision turning method for hard aluminum alloy thin-walled cover parts, characterized in that The method includes the following steps: Step S1, blank forging: According to the volume of the part blank, the raw material is cut into an appropriate length for forging. The number of forging times is not less than 3 times. Non-destructive testing is carried out before and after forging. Step S2, annealing of forgings: The forged blank parts are placed flat in an air furnace for annealing treatment. The blank parts are not stacked to prevent uneven heat absorption rate of the blank parts, resulting in insufficient release of internal forging stress. Step S3, rough turning of the outer shape: Draw a rough turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled housing parts. Leave a uniform allowance of 3-4 mm at each contour feature of the part according to the dimensions marked on the engineering drawing. Reserve a process flange with an appropriate thickness outside the open end of the part, reserve a solid process boss inside the closed end of the part, and reserve a solid process chuck outside the closed end of the part. Then rough turn the contour features of the inner hole and outer circle of the part according to the rough turning process sketch. Step S4, solution treatment: The hard aluminum alloy thin-walled housing parts after rough turning are subjected to solution treatment, that is, quenching treatment plus artificial aging, and the hardness and conductivity are detected. Step S5, first semi-finish turning: Draw a first semi-finish turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled housing parts. Leave a uniform allowance of 1 mm at each contour feature of the part according to the dimensions marked on the engineering drawing. Keep the process flange and the solid process boss, and remove the solid process chuck. Then semi-finish turn the contour features of the part in the order of inner hole first and then outer circle according to the first semi-finish turning process sketch. Step S6, artificial aging: The hard aluminum alloy thin-walled housing parts after the first semi-finish turning are placed flat in an air furnace with the open end facing up for artificial aging treatment. Step S7, second semi-finish turning: Draw a second semi-finish turning process sketch according to the engineering drawing of the hard aluminum alloy thin-walled housing parts. Leave a uniform allowance of 0.5 mm at each contour feature of the part according to the dimensions marked on the engineering drawing. Keep the solid process boss and remove the process flange. Then, with the help of the first tooling, semi-finish turn the contour features of the inner hole of the part and the solid process boss, and drill and tap an M8 flat-bottom thread hole on the solid process boss, with the depth less than the height of the solid process boss. Finally, use the second tooling to semi-finish turn the contour features of the outer circle of the part and remove the process flange. Step S8, artificial aging: The hard aluminum alloy thin-walled housing parts after the second semi-finish turning are placed flat in an air furnace with the open end facing up for artificial aging treatment. Step S9, finish turning: According to the engineering drawing of the hard aluminum alloy thin-walled housing parts, use the second tooling and the third tooling to clamp and align the hard aluminum alloy thin-walled housing parts, and successively finish turn all the contour features of the outer circle and inner hole of the hard aluminum alloy thin-walled housing parts to meet the requirements of the drawing dimensions, and remove the solid process boss. Step S10, natural aging: The hard aluminum alloy thin-walled housing parts after finish turning are placed flat on a marble platform with the open end facing up for natural aging treatment, and then sent for precision inspection.
2. The precision turning method for a hard aluminum alloy thin-walled housing part according to claim 1, wherein In the step S2, the annealing temperature is 360°C ± 5°C, the holding time is 3-4 hours, and it is cooled in the furnace to below 260°C and then air-cooled to room temperature. It is required that the temperature gradient during heating and cooling is not greater than 30°C / h.
3. A precision turning method for a hard aluminum alloy thin-walled cover part according to claim 1, characterized in that, In the step S3, an aluminum alloy turning tool with a shape of 80° or 55° is selected. The cutting speed is not greater than 260 m / min, the cutting depth is 0.3 - 0.5 mm, the feed rate is 32 - 38 mm / min, and the cutting fluid is flushed during the rough turning process.
4. A precision turning method for hard aluminum alloy thin-walled housing parts according to claim 1, characterized in that, In the step S3, the rough turning of the blank is carried out in three working steps according to the rough turning process sketch: First, the blank is turned into a regular cylinder, then the solid process chuck and the outer circle contour features of the part are rough turned, and finally, the outer circle of the part or the solid process chuck is clamped and aligned, and the process flange and the inner hole contour features are rough turned.
5. A precision turning method for a hard aluminum alloy thin-walled housing part according to claim 1, characterized in that, In the step S4, the quenching temperature is 495°C - 505°C, it is held in an air furnace for 210 - 360 min, water-cooled at 20°C - 60°C, and the transfer time of the part from the air furnace to the water tank does not exceed 20 seconds; subsequently, artificial aging is carried out on the part cooled to room temperature, the aging temperature is 185°C - 195°C, the holding time is 8 - 12 hours, and the time interval between quenching and artificial aging is less than 3 hours; the part is placed upright or inclined in the air furnace, and the water entry speed should be fast to prevent uneven distribution of quenching stress caused by uneven contact between the part and cold water.
6. A precision turning method for hard aluminum alloy thin-walled housing parts according to claim 1, characterized in that, In the step S5, a 55° aluminum alloy turning tool is selected. The cutting speed is not greater than 230 m / min, the cutting depth is 0.1 - 0.3 mm, the feed rate is 20 - 30 mm / min, the cutting fluid is flushed during the turning process, and the tool wear condition is observed in real time and the tool is replaced in time.
7. A precision turning method for a hard aluminum alloy thin-walled housing part according to claim 1, characterized in that In the step S5, after the first semi-finishing turning process is completed, the process flange is milled into a fan-shaped petal shape, and 8 groups of process threaded through holes are drilled and tapped at the corresponding positions on the end face of the process flange, aiming to weaken the hindrance of the integral circular process flange to the internal stress release of the part during the artificial aging in step S6, and at the same time facilitate the cooperation of the part and the first fixture in the second semi-finishing turning process in step S7 to realize the end face positioning and clamping of the part.
8. A precision turning method for a hard aluminum alloy thin-walled housing part according to claim 1, characterized in that, In the artificial aging of the step S6 and the step S8, an air furnace is used as the artificial aging equipment, the holding temperature is 190°C ± 20°C, the holding time is 6 - 8 hours, and the workpiece is taken out after being cooled to room temperature with the furnace. It is required that the temperature gradient of heating and cooling is not greater than 30°C / h.
9. A precision turning method for hard aluminum alloy thin-walled housing parts according to claim 1, characterized in that, In the step S7, a 55° aluminum alloy turning tool is selected for the second semi-finishing turning. The cutting speed is not greater than 180 m / min, the cutting depth is 0.05 - 0.1 mm, the feed rate is 10 - 20 mm / min, the cutting fluid is flushed during the turning process, and the tool wear condition is observed in real time and the tool is replaced in time.
10. A precision turning method for a hard aluminum alloy thin-walled housing part according to claim 1, characterized in that, In the step S7, the first tooling in the second semi-finishing turning process is of a rotary body structure, including a first tooling solid chuck, a concave cavity, a square process hole and a screw through hole. The first tooling solid chuck and the concave cavity are located at both ends of the first tooling and are coaxial. The first tooling solid chuck is used to connect with the three-jaw chuck of the machine tool. The concave cavity is used to accommodate the workpiece to be machined, and there is a certain gap between the concave cavity and the workpiece to be machined. There are 8 evenly distributed square process holes on the circumference of the first tooling, and 8 evenly distributed screw through holes are drilled on the upper end face of the first tooling, located at the center of the square process holes, and the screw through holes are communicated with the square process holes.
11. A precision turning method for a hard aluminum alloy thin-walled housing part according to claim 1, characterized in that, In the step S7 and the step S9, the second tooling is of a rotary body structure, including a second tooling solid chuck, a positioning stop, a spacer adapter, a spacer, a back-pull stud and a locking screw. The second tooling solid chuck, the positioning stop, the spacer adapter, the spacer and the back-pull stud are coaxial. The second tooling solid chuck is used to connect with the three-jaw chuck of the machine tool. The positioning stop is used to cooperate with the inner hole of the workpiece, and the cooperation gap is between 0.1 and 0.2 mm. The spacer adapter and the spacer are connected by a locking screw. The outer end face of the spacer is fitted with the plane at the center of the inner side of the workpiece. The back-pull stud is connected with the flat-bottom thread hole on the solid process boss to realize the positioning and clamping of the hard aluminum alloy thin-walled cover parts.
12. The precision turning method for a hard aluminum alloy thin-walled cover part according to claim 1, characterized in that, In the step S9, the third tooling in the finishing turning process is of a rotary body structure, including a third tooling solid chuck, an air pipe adapter interface, a process through hole, a workpiece positioning concave cavity, a sealing groove and an air passage. The third tooling solid chuck, the air pipe adapter interface, the workpiece positioning concave cavity and the sealing groove are coaxial. The third tooling solid chuck is connected with the three-jaw chuck of the machine tool. The air pipe adapter interface is connected with an air pipe adapter, and the air pipe adapter is connected with a vacuum pump through a hose. The process through hole is located on the outer circumference of the third tooling, which is convenient for alignment during workpiece clamping and exhaust when the workpiece is taken out. The workpiece positioning concave cavity is used to accommodate the workpiece and can be completely fitted with the arc surface of the closed end of the workpiece, and there is a certain gap in the circumferential direction, which is filled with butter. A soft elastic sealing ring is installed in the sealing groove. The air passage is connected with the air pipe adapter interface in a cross shape.
13. A precision turning method for a hard aluminum alloy thin-walled housing part according to claim 1, characterized in that, In the step S10, the natural aging treatment time is 96 hours.
Citation Information
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