Closed die forging forming method for aluminum alloy component with internal ribs in deep cavity having U-shaped notch

Abstract

Closed die forging forming method for aluminum alloy component with deep cavity rib and U-shaped notch. The present invention belongs to the field of forging. The present invention aims to solve the problems of low material utilization rate, large forming load and difficult demoulding during the forming of internal rib components with complex contours, especially when the centroid is not within the projection contour perpendicular to the loading direction of the press. The method includes: 1. Forging design; 2. Preform design; 3. Die design; 4. Preforming; 5. Demoulding and repairing; 6. Final forming. The present invention is used for the closed die forging forming of aluminum alloy components with deep cavity ribs and U-shaped notches.

Description

Technical Field

[0001] The invention belongs to the field of forging. Background Art

[0002] With the aerospace industry's requirements for higher speed, more agility and more economical aircraft, research on lightweighting has received more and more attention. Aluminum alloys have the advantages of low density, high specific strength and high stiffness, and are widely used in the aerospace field. The design of deep cavity rib structures with complex contours further reduces the weight of parts from the perspective of structural lightweighting. For such components, thick plate machining is usually used for production at this stage, which has relatively poor mechanical properties, causes a large amount of material waste and prolongs the machining time, and has high production costs; open die forging is the most commonly used forming method for die forgings, but the presence of die flash grooves will increase the die volume, and the flash generated by the forgings will also reduce the material utilization rate; closed die forging is a precision volume forming method with high material utilization rate. It is mainly used for rotating body components. For parts with complex shapes, the deformation resistance of one-step forming is too large, and it is difficult for ordinary equipment to meet the requirements. For components with more cross-rib structures, due to the large deformation resistance during rib forming and the large contact area with the die, it is often more difficult to demold the forging in the die to which the rib cavity belongs than in another die. Aluminum alloy is soft at high temperature. For aluminum alloy components whose center of mass is not within the projected contour perpendicular to the loading direction of the press, the forging will be difficult to eject and deform due to the uneven distribution of ejection force during single-point ejection. For two-step or multi-step forming, if the single-step pressing amount is too large, the lubricant between the billet and the mold will be carried away by the metal flow, increasing the friction, and the increase in load will make the compressive stress between the rib metal and the mold cavity too large, which will cause the forging to be difficult to eject and deform. Summary of the invention

[0003] The present invention aims to solve the problems of low material utilization, large forming load and difficult demolding when forming internal rib components with complex contours, especially those whose center of mass is not within the projected contour perpendicular to the loading direction of the press, and provides a closed die forging method for deep-cavity internal rib aluminum alloy components with U-shaped notches.

[0004] A closed die forging method for a deep cavity inner rib aluminum alloy component with a U-shaped notch is carried out according to the following steps:

[0005] 1. Forging design:

[0006] Design forgings based on deep cavity rib aluminum alloy parts with U-shaped notches;

[0007] The aluminum alloy part with internal ribs in a deep cavity having a U-shaped notch is composed of a web and side walls. The web is circular or nearly circular with a U-shaped notch, and there are criss-crossing reinforcing ribs on the web. The side walls are located at the edge of the web and have the same shape as the outer contour of the web; let the total length of the U-shaped notch be L U , let the maximum dimension of the part along the length direction of the U-shaped notch be L p , L U :L p =(0.5 - 0.7):1; let the maximum dimension of the part along the width direction of the U-shaped notch be B p , let the height of the side wall be H pr , when L p >B p , L p :H pr =(4 - 8):1, when L p ≤B p , B p :H pr =(4 - 8):1; let the thickness of the side wall be B pr , H pr :B pr =(3 - 6):1;

[0008] Specifically, for the forging, the bottom arched part of the U-shaped notch in the part is set to be nearly semi-circular, and the nearly semi-circular shape is used as the ejector block, so that the centroid of the forging falls at the center of the ejector block;

[0009] II. Preform design:

[0010] Design the preform according to the forging;

[0011] The preform is a plate-shaped blank with variable thickness. In the direction perpendicular to the loading direction of the press, the projected contour shape of the preform is the same as that of the forging; and along the symmetry plane of the preform, from the side of the preform far from the bottom of the U-shaped notch to the intersection of the top of the U-shaped notch and the preform contour, the thickness gradually increases; when the preform and the forging contours coincide, make a plane parallel to the loading direction of the press and perpendicular to the symmetry plane through the centroid position of the forging. The plane divides the forging and the preform respectively. Let the part not including the U-shaped notch be the front part, and the part including the U-shaped notch be the rear part. The volume ratio of the front and rear parts of the forging is K f , the volume ratio of the front and rear parts of the preform is K b , K f / K b =0.8 - 1;

[0012] III. Die design:

[0013] The forming die has a closed positive extrusion die structure, including an upper die and a lower die. The rib cavity is located in the lower die, and the lower die corresponding to the area where the forging ejection block is located is a movable ejector block. The upper die includes two parts, a fixed upper die and a movable upper die. The fixed upper die is a flat anvil with a heating hole, and the movable upper die is a thick plate. The outer contour shape and size of the thick plate are the same as those of the forging.

[0014] IV. Pre-forming:

[0015] After heating, lubricating and positioning the forming die and the preform blank described in Step III, pre-forming is carried out. During the pre-forming process, the pressing speed of the press is 0.3 mm / s to 3 mm / s. When the stroke of the pre-forming press makes the upper and lower dies reach the underpressure height, the forming is stopped to obtain a preformed part.

[0016] The specific underpressure height is the underpressure height corresponding to when using an equal-thickness plate blank with the same contour and volume as the forging, and the pre-forming reduction is 65% to 75% of the standard total reduction.

[0017] V. Die removal and part repair:

[0018] The preformed part is taken out and air-cooled to room temperature, then pickled and repaired, and finally smoothed to obtain a repaired preformed part.

[0019] VI. Final forming:

[0020] After heating, lubricating and positioning the repaired preformed part and the forming die described in Step III, final forming is carried out. During the final forming process, the pressing speed of the press is 0.3 mm / s to 3 mm / s. When the stroke of the final forming press makes the upper and lower dies reach the underpressure height, the forming is stopped, and the die is removed to obtain a forging.

[0021] The specific underpressure height is the underpressure height corresponding to when using an equal-thickness plate blank with the same contour and volume as the forging, and the total reduction of pre-forming and final forming is 95% to 100% of the standard total reduction.

[0022] The beneficial effects of the present invention are:

[0023] The present invention aims at the problems of low material utilization rate, large forming load, and difficult forging demoulding existing in the forming of large-size deep cavity internal rib aluminum alloy components (with U-shaped notches) whose centroid is not within the projection plane of the part. It designs a forging with the centroid within the projection plane and at the center of the ejector block, so that the ejecting forces received by each position during forging ejection are relatively balanced. It develops a closed die forward extrusion two-step forming process with the rib cavity located in the lower die, improves the material utilization rate, reduces the die volume, and lowers the production cost by means of closed die forging; by adopting the forward extrusion method with the rib cavity placed in the lower die, it prevents the situation that the forging may be stuck in the upper die and difficult to demould. By designing the upper die into two parts, the movable upper die and the fixed upper die, it avoids the situation that the upper and lower dies are locked due to extruded burrs. According to the volume ratio of different positions of the forging, the shape of the preform is reasonably designed to preferentially fill the sharp corners of the U-shaped notch where the forging is difficult to fill, and the intermediate trimming of the two-step forming is adopted to further optimize the distribution of the metal volume. The overall filling speed of the forging is relatively uniform, reducing the forming load and the demoulding difficulty. By reasonably distributing the single-step reduction amount in the two-step forming, it prevents excessive loss of lubricant and excessive increase of the compressive stress between the rib and the die, enabling the forging to be smoothly demoulded, reducing the possible folding depth generated by preforming, and lowering the trimming difficulty. After preforming, the forging is trimmed to a certain extent to cut off the locally overfilled parts, reducing the final forming load and no defects are generated in the final forming.

[0024] The present invention relates to a closed die forging forming method for deep cavity internal rib aluminum alloy components with U-shaped notches. Brief Description of the Drawings

[0025] Figure 1 It is the top view of the deep cavity internal rib aluminum alloy part with a U-shaped notch described in Step 1 of the embodiment, G p is the centroid of the part;

[0026] Figure 2 It is the three-dimensional view of the deep cavity internal rib aluminum alloy part with a U-shaped notch described in Step 1 of the embodiment;

[0027] Figure 3 It is Figure 1 the sectional view along A-A in

[0028] Figure 4 It is the top view of the forging described in Step 1 of the embodiment, G f is the centroid of the forging, P is the plane parallel to the press loading direction and perpendicular to the symmetry plane passing through the centroid position of the forging, F is the front part of the forging, and B is the rear part of the forging;

[0029] Figure 5 It is the three-dimensional view of the forging described in Step 1 of the embodiment;

[0030] Figure 6Schematic diagram of the final forming structure in Step 6 of Embodiment 1, where 1 is the fixed upper die, 2 is the movable upper die, 3 is the lower die, 4 is the movable ejector block, and 5 is the forging;

[0031] Figure 7 Top view of the lower die described in Step 3 of Embodiment 1, where 4 is the movable ejector block;

[0032] Figure 8 Stereogram of the lower die described in Step 3 of Embodiment 1;

[0033] Figure 9 Stereogram of the fixed upper die described in Step 3 of Embodiment 1;

[0034] Figure 10 Stereogram of the movable upper die described in Step 3 of Embodiment 1;

[0035] Figure 11 Top view of the preform described in Step 2 of Embodiment 1, where P is the plane parallel to the loading direction of the press and perpendicular to the symmetry plane passing through the centroid position of the forging when the preform and the forging contours coincide, F is the front part of the preform, and B is the rear part of the preform;

[0036] Figure 12 Stereogram of the preform described in Step 2 of Embodiment 1;

[0037] Figure 13 Top view of the preform described in Step 2 of Comparative Example 1, where P is the plane parallel to the loading direction of the press and perpendicular to the symmetry plane passing through the centroid position of the forging when the preform and the forging contours coincide, F is the front part of the preform, and B is the rear part of the preform;

[0038] Figure 14 Stereogram of the preform described in Step 2 of Comparative Example 1;

[0039] Figure 15 Physical diagram of the preform prepared in Step 4 of Embodiment 1, (a) is the top view, and (b) is the side view;

[0040] Figure 16 Physical diagram of the forging prepared in Step 6 of Embodiment 1;

[0041] Figure 17 Equipment display interface diagram when the press reaches the specified stroke in Step 6 of Embodiment 1;

[0042] Figure 18 Finite element simulation load curve diagram for one-step forming in Comparative Example 2;

[0043] Figure 19 Physical diagram of the preform in Comparative Example 1, (a) is the side view of the preform with graphite lubricant in Step 4, and (b) is the top view of the pickled preform in Step 5. Specific Embodiments

[0044] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination between the specific embodiments.

[0045] Specific Embodiment 1: The closed die forging forming method of the aluminum alloy component with a U-shaped notch in a deep cavity rib described in this embodiment is carried out according to the following steps:

[0046] I. Forging design:

[0047] Design the forging according to the aluminum alloy part with a U-shaped notch in a deep cavity rib;

[0048] The aluminum alloy part with a U-shaped notch in a deep cavity rib is composed of a web and side walls. The web is circular or nearly circular with a U-shaped notch, and there are criss-crossing reinforcing ribs on the web. The side walls are located at the edge of the web and have the same shape as the outer contour of the web; Let the total length of the U-shaped notch be L U , let the maximum dimension of the part along the length direction of the U-shaped notch be L p , L U :L p =(0.5 - 0.7):1; Let the maximum dimension of the part along the width direction of the U-shaped notch be B p , let the height of the side wall be H pr , when L p >B p , L p :H pr =(4 - 8):1, when L p ≤B p , B p :H pr =(4 - 8):1; Let the thickness of the side wall be B pr , H pr :B pr =(3 - 6):1;

[0049] Specifically, the bottom arched part of the U-shaped notch in the part is set as a nearly semi-circular shape, and the nearly semi-circular shape is used as the ejector block, so that the centroid of the forging falls on the center of the ejector block;

[0050] II. Preform design:

[0051] Design the preform according to the forging;

[0052] The preform is a plate-shaped blank with variable thickness. In the direction perpendicular to the loading direction of the press, the projected contour shape of the preform is the same as that of the forging. And along the symmetry plane of the preform, from the side of the preform away from the bottom of the U-shaped notch to the intersection of the top of the U-shaped notch and the preform contour, the thickness gradually increases. When the preform and the forging contour coincide, a plane parallel to the loading direction of the press and perpendicular to the symmetry plane is made through the centroid position of the forging. The plane divides the forging and the preform respectively. Let the part not including the U-shaped notch be the front part, and the part including the U-shaped notch be the rear part. The volume ratio of the front and rear parts of the forging is K f , and the volume ratio of the front and rear parts of the preform is K b , K f / K b = 0.8 - 1;

[0053] III. Die design:

[0054] The forming die is a closed positive extrusion die structure, including an upper die and a lower die. The rib cavity is located in the lower die, and the lower die corresponding to the area where the forging ejector block is located is a movable ejector block. The upper die includes two parts: a fixed upper die and a movable upper die. The fixed upper die is a flat anvil with a heating hole, and the movable upper die is a thick plate, and the outer contour shape and size of the thick plate are the same as those of the forging;

[0055] IV. Preforming:

[0056] After heating, lubricating and positioning the forming die and the preform described in step III, preforming is carried out. During the preforming process, the pressing speed of the press is 0.3 mm / s - 3 mm / s. When the stroke of the preforming press makes the upper and lower dies reach the underpressure height, the forming is stopped to obtain a preformed part;

[0057] The underpressure height specifically refers to the underpressure height corresponding to the case when using an equal-thickness plate blank with the same contour and volume as the forging, and the preforming reduction is 65% - 75% of the standard total reduction;

[0058] V. Die removal and part repair:

[0059] The preformed part is taken out and air-cooled to room temperature, then pickled and part-repaired, and finally smoothed to obtain the preformed part after repair;

[0060] VI. Final forming:

[0061] After heating, lubricating and positioning the preformed part after repair and the forming die described in step III, final forming is carried out. During the final forming process, the pressing speed of the press is 0.3 mm / s - 3 mm / s. When the stroke of the final forming press makes the upper and lower dies reach the underpressure height, the forming is stopped and the die is removed to obtain the forging;

[0062] The specific underpressure height is the underpressure height corresponding to the total reduction in height during preforming and final forming being 95% - 100% of the standard total reduction in height when using an equal-thickness plate-shaped blank with the same volume and contour as the forging.

[0063] The beneficial effects of this embodiment are as follows:

[0064] For the forming of large-sized deep-cavity ribbed aluminum alloy components with a U-shaped notch and the centroid not within the projection plane of the part, which has problems such as low material utilization rate, large forming load, and difficult forging ejection, this embodiment designs a forging with the centroid within the projection plane and at the center of the ejector block, making the ejection force at each position of the forging more balanced during ejection. A closed-die forward extrusion two-step forming process with the rib cavity located in the lower die is developed. By means of closed-die forging, the material utilization rate is increased, the die volume is reduced, and the production cost is lowered; by adopting the forward extrusion method with the rib cavity placed in the lower die, the situation where the forging may get stuck in the upper die and be difficult to eject is prevented. By designing the upper die as two parts, a movable upper die and a fixed upper die, the situation where the upper and lower dies are locked due to extruded burrs is avoided. According to the volume ratio of different positions of the forging, the shape of the preform is reasonably designed to preferentially fill the sharp corners of the U-shaped notch where the forging is difficult to fill, and the method of intermediate trimming during two-step forming is adopted to further optimize the distribution of the metal volume. The overall filling speed of the forging is relatively uniform, reducing the forming load and the ejection difficulty. By reasonably distributing the reduction in height for each step in the two-step forming, excessive loss of lubricant and excessive increase in the compressive stress between the rib and the die are prevented, enabling the forging to be ejected smoothly, reducing the possible folding depth during preforming, and lowering the trimming difficulty. After preforming, the forging is trimmed to a certain extent to cut off the locally overfilled parts, reducing the final forming load and ensuring no defects in the final forming.

[0065] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: the deep-cavity ribbed aluminum alloy part with a U-shaped notch described in Step 1 is a left-right symmetric structure, and the symmetry plane of the U-shaped notch is the symmetry plane of the part. Others are the same as Specific Embodiment 1.

[0066] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that: the machining allowance for each part of the forging described in Step 1 is 3 mm - 8 mm. Others are the same as Specific Embodiment 1 or 2.

[0067] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that: the draft angle of the forging described in Step 1 is 3° - 10°. Others are the same as Specific Embodiments 1 to 3.

[0068] Embodiment 5: The difference between this embodiment and any one of Embodiments 1 to 4 is that in Step 1, the transition fillet radius between the rib and the web on the part is 10 mm to 20 mm, and the fillet radius at the top of the rib is 2 mm to 5 mm. Others are the same as those in Embodiments 1 to 4.

[0069] Embodiment 6: The difference between this embodiment and any one of Embodiments 1 to 5 is that in Step 2, the volume of the preform is 1.05 to 1.15 times the volume of the forging. Others are the same as those in Embodiments 1 to 5.

[0070] Embodiment 7: The difference between this embodiment and any one of Embodiments 1 to 6 is that in Step 3, the edge of the movable upper die is chamfered with a fillet radius r = 7 mm to 15 mm. Others are the same as those in Embodiments 1 to 6.

[0071] Embodiment 8: The difference between this embodiment and any one of Embodiments 1 to 7 is that in Steps 4 and 6, the standard total reduction is the reduction when the upper and lower dies are fully closed. Others are the same as those in Embodiments 1 to 7.

[0072] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is that after the part is repaired in Step 5, 2 mm to 10 mm of the height at the position where the side wall of the preform is filled too fast and the forming height is relatively large is milled off. Others are the same as those in Embodiments 1 to 8.

[0073] Embodiment 10: The difference between this embodiment and any one of Embodiments 1 to 9 is that in Step 5, the preform is taken out and air-cooled to room temperature, then pickled to remove the surface lubricant, the folds and longitudinal burrs are removed, and finally the surface is smoothed to obtain the preform after repair. Others are the same as those in Embodiments 1 to 9.

[0074] The following examples are used to verify the beneficial effects of the present invention:

[0075] Example 1, combined with Figures 1 to 12 Specific description:

[0076] The closed die forging forming method of a deep cavity rib aluminum alloy component with a U-shaped notch is carried out according to the following steps:

[0077] 1. Forging design:

[0078] Design the forging according to the deep cavity rib aluminum alloy part with a U-shaped notch;

[0079] The aluminum alloy part with internal ribs in a deep cavity having a U-shaped notch is composed of a web and side walls. The web is nearly circular with a U-shaped notch, and there are criss-crossing reinforcing ribs on the web. The side walls are located at the edge of the web and have the same shape as the outer contour of the web; the total length of the U-shaped notch is L U = 360 mm, and the maximum dimension of the part along the length direction of the U-shaped notch is L p = 635 mm, L U :L p = 0.57:1; the maximum dimension of the part along the width direction of the U-shaped notch is B p = 708 mm, and the height of the side wall is H pr = 104.5 mm, L p <B p ,B p :H pr = 6.78:1; the thickness of the side wall is B pr = 26 mm, H pr :B pr = 4.02:1;

[0080] Specifically, for the forging, the bottom arched part of the U-shaped notch in the part is set to be nearly semi-circular, and the nearly semi-circular shape is used as the ejector block, so that the centroid of the forging falls on the center of the ejector block;

[0081] II. Preform design:

[0082] Design the preform according to the forging;

[0083] The preform is a plate-shaped blank with a variable thickness. In the direction perpendicular to the loading direction of the press, the projected contour shape of the preform is the same as that of the forging; and along the symmetry plane of the preform, from the side of the preform far from the bottom of the U-shaped notch to the intersection of the top of the U-shaped notch and the preform contour, the thickness gradually increases, with the thinnest part being 63 mm and the thickest part being 109 mm; when the preform and the forging contours coincide, make a plane parallel to the loading direction of the press and perpendicular to the symmetry plane through the centroid position of the forging. The plane divides the forging and the preform respectively. Let the part not including the U-shaped notch be the front part, and the part including the U-shaped notch be the rear part. The volume ratio of the front and rear parts of the forging is K f , and the volume ratio of the front and rear parts of the preform is K b , K f / K b = 0.93;

[0084] III. Die design:

[0085] The forming die is a closed-type forward extrusion die structure, including an upper die and a lower die. The rib cavity is located in the lower die, and the lower die corresponding to the area where the forging ejection block is located is a movable ejector block. The upper die includes two parts: a fixed upper die and a movable upper die. The fixed upper die is a flat anvil with a heating hole, and the movable upper die is a thick plate. The outer contour shape and size of the thick plate are the same as those of the forging.

[0086] IV. Pre-forming:

[0087] After heating, lubricating and positioning the forming die and the preform blank described in step III, pre-forming is carried out. During the pre-forming process, the pressing speed of the press is 2.5 mm / s. When the stroke of the pre-forming press makes the upper and lower dies reach the underpressure height, the forming is stopped to obtain a preformed part.

[0088] The specific underpressure height is the underpressure height corresponding to when using a thick plate blank with the same contour and volume as the forging, and the pre-forming reduction is 75% of the standard total reduction.

[0089] V. Die removal and part repair:

[0090] The preformed part is taken out and air-cooled to room temperature, then pickled and repaired, and finally smoothed to obtain the repaired preformed part.

[0091] VI. Final forming:

[0092] After heating, lubricating and positioning the repaired preformed part and the forming die described in step III, final forming is carried out. During the final forming process, the pressing speed of the press is 2.5 mm / s. When the stroke of the final forming press makes the upper and lower dies reach the underpressure height, the forming is stopped and the die is removed to obtain the forging.

[0093] The specific underpressure height is the underpressure height corresponding to when using a thick plate blank with the same contour and volume as the forging, and the total reduction of pre-forming and final forming is 96% of the standard total reduction.

[0094] The material of the forging designed for the aluminum alloy part with deep cavity ribs and a U-shaped notch described in step I is 5A06 aluminum alloy.

[0095] The aluminum alloy part with deep cavity ribs and a U-shaped notch described in step I is a left-right symmetric structure, and the symmetry plane of the U-shaped notch is the symmetry plane of the part.

[0096] The machining allowance for each part of the forging described in step I is 3 mm to 7.5 mm.

[0097] The draft angle of the forging described in step I is 5° to 7°.

[0098] The transition fillet radius between the stiffener and the web on the part in step I is 10 mm, and the fillet radius at the top of the stiffener is 2 mm.

[0099] The volume of the preform described in Step 2 is 1.15 times the volume of the forging.

[0100] The edge of the movable upper die described in Step 3 is rounded, and the fillet radius r = 10 mm.

[0101] The standard total reduction described in Step 4 and Step 6 is the reduction when the upper and lower dies are fully closed.

[0102] In Step 5, the preform is taken out and air-cooled to room temperature, then pickled to remove the surface lubricant, the folds and longitudinal burrs are removed, then the position with a relatively large forming height caused by excessive local filling on the side wall of the preform is milled off by 2 mm in height, and finally the surface is smoothed to obtain the preform after repair.

[0103] Comparative Example 1, combined with Figure 13 and Figure 14 :

[0104] The difference between this comparative example and Example 1 is as follows: In Step 2, along the symmetry plane of the preform, from the side of the preform far from the bottom of the U-shaped notch to the bottom of the U-shaped notch, the thickness is the same, both 75 mm. Along the symmetry plane of the preform, from the bottom of the U-shaped notch to the intersection of the top of the U-shaped notch and the contour of the preform, the thickness gradually increases, and the thickest part is 109 mm. The underpressure height described in Step 4 is specifically the underpressure height corresponding to when using a thick plate blank with the same contour and volume as the forging and the preforming reduction is 90% of the standard total reduction. The other steps are the same as those in Example 1.

[0105] Comparative Example 2: The difference between this comparative example and Example 1 is that the forging is formed in one step and fully pressed down in place. The other steps are the same as those in Example 1.

[0106] Figure 15 Figure (a) is the top view and Figure (b) is the side view of the physical drawing of the preform prepared in Step 4 of Example 1; Figure 16 Figure is the physical drawing of the forging prepared in Step 6 of Example 1; It can be seen from the figure that no deformation occurs during the demoulding process of the preform and the final formed part.

[0107] Figure 17 Figure is the equipment display interface diagram when the press reaches the specified stroke in Step 6 of Example 1; It can be seen from the figure that in the two-step forming process design of Example 1, the actual maximum load measured by the press during the actual forming process is only 4686 t.

[0108] Figure 18 Figure is the finite element simulation load curve diagram of the one-step forming in Comparative Example 2; It can be seen from the figure that the maximum load reaches more than 10000 t.

[0109] Figure 19It is a physical drawing of the preform for Comparative Example 1. (a) is a side view of the preform with graphite lubricant in Step 4, and (b) is a top view of the pickled preform in Step 5. It can be seen from the figure that due to the excessive reduction in the preforming process, it is very difficult to eject the forged part, and serious ejection deformation occurs on the back of the preform.

Claims

1. Closed die forging forming method for aluminum alloy component with internal ribs in deep cavity having U-shaped notch, characterized in that It is carried out according to the following steps:

1. Forging design: Design the forging according to the aluminum alloy part with deep cavity ribs and a U-shaped notch; The aluminum alloy part with internal ribs in a deep cavity having a U-shaped notch is composed of a web and side walls. The web is circular or nearly circular with a U-shaped notch, and there are criss-crossing reinforcing ribs on the web. The side walls are located at the edge of the web and have the same shape as the outer contour of the web. Let the total length of the U-shaped notch be L U , and let the maximum dimension of the part along the length direction of the U-shaped notch be L p , L U :L p =(0.5 - 0.7):1; Let the maximum dimension of the part along the width direction of the U-shaped notch be B p , and let the height of the side wall be H pr , when L p >B p , L p :H pr =(4 - 8):1, when L p ≤B p , B p :H pr =(4 - 8):1; Let the thickness of the side wall be B pr , H pr :B pr =(3 - 6):1; Specifically, the bottom arched part of the U-shaped notch in the part is set as a nearly semi-circular shape, and the nearly semi-circular shape is used as the ejector block, so that the centroid of the forging falls on the center of the ejector block; 2. Preform design: Design the preform according to the forging; The preform is a plate-shaped blank with variable thickness. In the direction perpendicular to the loading direction of the press, the projection profile shape of the preform is the same as that of the forging. And along the symmetry plane of the preform, the thickness gradually increases from the side of the preform far from the bottom of the U-shaped notch to the intersection of the top of the U-shaped notch and the preform profile. When the preform and the forging profile coincide, a plane parallel to the loading direction of the press and perpendicular to the symmetry plane is made through the centroid position of the forging. The plane divides the forging and the preform respectively. Let the part not including the U-shaped notch be the front part, and the part including the U-shaped notch be the rear part. The volume ratio of the front and rear parts of the forging is K f , the volume ratio of the front and rear parts of the preform is K b , K f / K b = 0.8 to 1; 3. Die design: The forming die is a closed positive extrusion die structure, including an upper die and a lower die. The rib cavity is located in the lower die, and the lower die corresponding to the area where the ejector block of the forging is located is a movable ejector block. The upper die includes two parts, a fixed upper die and a movable upper die. The fixed upper die is a flat anvil with a heating hole, and the movable upper die is a thick plate, and the outer contour shape and size of the thick plate are the same as those of the forging; 4. Preforming: After heating, lubricating and positioning the forming die and the preform described in step 3, preforming is carried out. During the preforming process, the pressing speed of the press is 0.3mm / s to 3mm / s. When the stroke of the preforming press makes the upper and lower dies reach the underpressure height, the forming is stopped to obtain a preformed part; The specific underpressure height is the underpressure height corresponding to when using an equal-thickness plate blank with the same contour and volume as the forging, and the preforming reduction is 65% to 75% of the standard total reduction; 5. Die removal and part repair: Take out the preformed part and air-cool it to room temperature, then pickling and part repair, and finally smooth treatment to obtain the preformed part after repair; 6. Final forming: After heating, lubricating and positioning the preformed part after repair and the forming die described in step 3, final forming is carried out. During the final forming process, the pressing speed of the press is 0.3mm / s to 3mm / s. When the stroke of the final forming press makes the upper and lower dies reach the underpressure height, the forming is stopped and demoulded to obtain the forging; The specific underpressure height is the underpressure height corresponding to when using an equal-thickness plate blank with the same contour and volume as the forging, and the total reduction of preforming and final forming is 95% to 100% of the standard total reduction; 2. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 1, characterized in that The aluminum alloy part with deep cavity ribs and a U-shaped notch described in step 1 has a left-right symmetric structure, and the symmetry plane of the U-shaped notch is the symmetry plane of the part; 3. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 1, characterized in that The machining allowance for each part of the forging described in step 1 is 3mm to 8mm; 4. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 3, characterized in that The draft angle of the forging described in step 1 is 3° to 10°; 5. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 1, characterized in that The transition fillet radius between the stiffener and the web on the part in step 1 is 10mm to 20mm, and the fillet radius at the top of the stiffener is 2mm to 5mm; 6. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 1, characterized in that The volume of the preform described in step 2 is 1.05 times to 1.15 times the volume of the forging; 7. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 1, characterized in that The edge of the movable upper die described in step 3 is rounded, and the fillet radius r = 7mm to 15mm; 8. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 1, characterized in that The standard total reduction described in steps 4 and 6 is the reduction when the upper and lower dies are fully closed; 9. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 1, characterized in that After part repair in step 5, mill 2mm to 10mm in height at the position where the side wall of the preformed part is filled too fast and the forming height is relatively large; 10. The closed die forging forming method of the aluminum alloy component with internal ribs in a deep cavity having a U-shaped notch according to claim 9, characterized in that In step 5, take out the preformed part and air-cool it to room temperature, then pickling to remove the surface lubricant, remove the folds and longitudinal burrs, and finally smooth the surface to obtain the preformed part after repair.

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