A forging method for integral frame forgings using bar stock

Abstract

This invention belongs to the field of forging hot working, and specifically relates to a forging method for forging integral frame forgings using bar stock. The method includes: blanking; placing the bar stock on an anvil for upsetting along its height; reheating the upset bar stock in a furnace, then flattening it to obtain a blank; further upsetting the blank along its diagonal to compress the metal at the four corners, thus increasing the local thickness of the blank, ultimately obtaining a first intermediate blank; punching and enlarging the first intermediate blank to obtain a second intermediate blank with two symmetrical through holes; widening and elongating the second intermediate blank to obtain a third intermediate blank; locally elongating the third intermediate blank, with the elongation area being the middle region along its length, completing the blank forging; and pre-forging and final forging the blank to obtain the forging.

Description

Technical Field

[0001] This invention belongs to the field of hot forging, and specifically relates to a forging method for forging integral frame forgings using bar stock. Background Technology

[0002] This is a solid frame forging for a certain type of aircraft. The forging material is titanium alloy. The forging structure is characterized by a large outline, a large projected area, and a thin web. The forging has a bilaterally symmetrical structure with two through holes arranged in the middle of each side, resembling an eyeglass frame. The difference between the maximum and minimum cross-sectional dimensions of the forging is significant, with a cross-sectional ratio of 10.4:1, making the forging structure complex.

[0003] Due to the large weight and projected area of ​​forgings, and their complex structure, existing raw material bars cannot meet the forming requirements. Therefore, the current forging methods all use rectangular billets of uniform thickness as raw materials, followed by thinning the connecting skin using a die or free forging method (e.g., patent numbers CN105215240.A and 113245492.A), and then using a special die made according to the shape and size of the forging for pre-forging and final forging operations to complete the forging shape. In the implementation of this method, regardless of whether a die or free forging is used, thinning the connecting skin is the main method. The metal of the connecting skin needs to be removed, resulting in high raw material consumption. Furthermore, as the thickness of the connecting skin decreases, the deformation resistance increases sharply, and the demand for equipment tonnage also increases. At the same time, the price of plate stock is much higher than that of bar stock, so the production cost of forgings is very high. Summary of the Invention

[0004] The purpose of this invention is to propose a forging method for producing integral frames. The raw material used is commonly available bar stock. Through specialized billet-making tools and forging methods, this method ensures the forming of the forging while reducing raw material consumption and lowering raw material costs. Simultaneously, it improves the uniformity of forging deformation, thereby guaranteeing a high yield rate.

[0005] Technical solution:

[0006] A forging method for producing integral frame forgings using bar stock is provided, comprising:

[0007] Material feeding;

[0008] The bar stock is placed on the anvil and upset along the height direction;

[0009] After the upsetting is completed, the bar stock is reheated in the furnace, then flattened and forged to obtain a blank. The blank is then upset along the diagonal to compress the metal at the four corners and increase the local thickness of the blank, finally obtaining the first intermediate billet.

[0010] The first intermediate billet is punched and enlarged to obtain a second intermediate billet with two symmetrical through holes;

[0011] The second intermediate billet is widened and lengthened to obtain the third intermediate billet;

[0012] The third intermediate billet is partially elongated, with the elongation area being the middle area along the length direction, to complete the rough forging.

[0013] The rough shape is pre-forged and then forged to obtain the forging.

[0014] Furthermore, both the upper and lower dies of the pre-forging are equipped with upper and lower punches corresponding to the symmetrical through holes;

[0015] The upper punch consists of two square platforms with different slopes and a large arc transition. The top of the upper platform is removed, and the connecting surfaces of the upper and lower platforms completely overlap. The lower punch includes a square boss and a square platform with a slope. The square boss and the square platform with a slope transition with an arc.

[0016] Furthermore, the width of the inclined surface XL1 near the middle of the lower punch is smaller than the widths of the other three inclined surfaces XL2, XL3, and XL4; XL2, XL3, and XL4 are the same, being 1.6 to 2.0 times XL1.

[0017] The width of the inclined surface SL1 near the middle of the lower platform of the upper punch is smaller than the widths of the other three inclined surfaces SL2, SL3, and SL4; the widths of SL2, SL3, and SL4 are the same, which are 1.6 to 2.0 times SL1.

[0018] The width of the four inclined surfaces of the lower punch is smaller than the width of the corresponding inclined surface of the lower platform of the upper punch;

[0019] The four ramps on the upper platform of the punch are all the same width, which is 2.0 to 2.4 times SL1.

[0020] Further, pre-forging includes:

[0021] First heat: Press until the vertical distance between the upper and lower dies is 32mm; after forging, the rough shape is raised and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining;

[0022] Second heat: Press until the upper and lower molds are to the dimensions required by the drawing;

[0023] The forging temperature is 940℃~975℃, and the pressing speed is 4~6mm / s.

[0024] Furthermore, the first intermediate billet is punched and enlarged to obtain a second intermediate billet with two symmetrical through holes, including:

[0025] For any through hole, place the first intermediate blank flat on the hammer anvil, place the two heated punches on the first intermediate blank, and punch the hole. The punches are placed at the center of the width of the first intermediate blank, and symmetrically placed 320mm away from the center in the length direction.

[0026] After punching is completed, the hole is enlarged twice more.

[0027] Further, the bar stock is placed on a hammer anvil for upsetting along the height direction, including:

[0028] For bar stock with a height-to-diameter ratio greater than 4.5, a collar is attached to one end of the bar stock during upsetting, so that the area of ​​the bar stock outside the collar deforms, achieving local upsetting while ensuring that the height-to-diameter ratio is less than 4.5.

[0029] Remove the collar and proceed with the second upsetting;

[0030] During this process, the forging temperature is 940℃~975℃.

[0031] Furthermore, the collar is a cylindrical structure with a blind hole at one end. The diameter of the blind hole is 5 to 10 mm larger than the diameter of the bar stock, and the depth of the blind hole is 0.25 to 0.3 times the length of the bar stock.

[0032] Furthermore, the wall thickness of the collar is 0.4 to 0.6 times the diameter of the bar stock, and the material used for the collar is ordinary mold steel or structural steel.

[0033] Beneficial effects: Forgings obtained using this method show significantly improved material utilization, high forging pass rate, and stable forging quality. The punch, pre-forging die, and final forging die are all made of hot-work die steel. The beneficial effects of this invention are that the use of dedicated punches and pre-forging dies solves the problem of filling the outer ribs when producing integral frame forgings from bar stock, improving the forging pass rate, avoiding forging scrap due to insufficient material or clamping damage, increasing the forging pass rate and product stability, while also expanding the range of raw materials that can be selected for forgings and reducing forging production costs. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the mold closing mechanism of the pre-forging mold of the present invention;

[0035] Figure 2 This is a front view of the pre-forging lower mold cavity of the present invention;

[0036] Figure 3 This is a front view of the pre-forging upper mold cavity of the present invention. Detailed Implementation

[0037] This invention provides a method for forging an integral frame-type titanium alloy, comprising:

[0038] For material preparation, firstly, machine both ends of the raw material bar to ensure that they are perpendicular to the bar, and round the edges of both ends to R15mm.

[0039] Step 2: Then heat it in a furnace to the forging temperature.

[0040] Step 3: Place the heated bar stock on the anvil for upsetting. For bars with a height-to-diameter ratio greater than 4.5, attach a collar to one end of the bar stock during upsetting. This causes deformation in the area outside the collar, achieving localized upsetting and preventing double upsetting. Then remove the collar and perform a second upsetting. During this process, the forging temperature is 940℃~975℃, and the collar material is ordinary hot work die steel.

[0041] Step 4: After upsetting, the bar stock is reheated in the furnace. The heated billet is flattened and forged into a square. Then, the billet is upset along the diagonal, extruding the metal from the four corners into the thickness direction of the billet. This becomes the first intermediate billet, with the length direction of the bar stock remaining unchanged from the length direction of the billet.

[0042] Step 5: After the first intermediate billet has been shaped, it is reheated in the furnace, while heating six punches at the same time: two small punches, two medium punches and two large punches.

[0043] Place the first intermediate billet flat on the anvil. Place a heated small punch on the billet, centering it at the width of the billet. Two small punches are placed symmetrically along the length of the billet, with a center-to-center distance of 640 mm, and punch holes. After punching, replace the small punch with a medium-sized punch for the first hole enlargement. Then replace the medium-sized punch with a large punch for the second hole enlargement. After punching and the two enlargement operations, the second intermediate billet is obtained.

[0044] Step 6: Reheat the second intermediate billet in the furnace. Widen the heated second intermediate billet, elongate it along the width of the rough billet, and then elongate it along the length to obtain the third intermediate billet.

[0045] Step 7: Reheat the third intermediate billet in the furnace. The heated third intermediate billet is then drawn again, specifically the middle region along its length. This drawing of the middle region of the billet completes the rough forging process.

[0046] The rough shape was then air-cooled to room temperature. Surface defects were then removed by polishing.

[0047] Step 8: Heat the rough shape; simultaneously heat the pre-forging die. After heating, perform pre-forging; the first heat presses the rough shape to a vertical distance of 25-40mm from the impact surfaces of the upper and lower dies. After forging, lift the rough shape and air-cool it to room temperature. Machine-remove burrs and brittle edges from the forging, and polish to remove surface defects. Heat the rough shape again, and after heating, perform a second pre-forging heat, pressing the rough shape to a vertical distance of 8-15mm from the upper and lower dies. The pressing speed is 4-6mm / s.

[0048] Step 9: Air-cool the rough shape to room temperature, then remove the burrs and lining of the pre-forged part by machining, and use grinding to remove surface defects of the rough shape.

[0049] Step 10: Heat the rough shape; simultaneously heat the final forging die. After heating, perform pre-forging; the first forging presses the rough shape to a vertical distance of 10-22mm between the upper and lower dies. After forging, lift the rough shape and air-cool it to room temperature. Machine-remove the burrs and lining skin from the forging, leaving a 10-22mm lining skin. Grind to remove surface defects from the rough shape. Heat the rough shape again; after heating, perform a second forging press, pressing it to the dimensions required by the drawing. The pressing speed is 4-6mm / s.

[0050] Step 11: Air-cool the rough shape to room temperature, then remove the burrs and lining of the forging by machining, and use grinding to remove surface defects of the rough shape.

[0051] Step 12: Heat treat the forging.

[0052] The collar in step 1 is a cylindrical structure with a blind hole at one end. The diameter of the blind hole is 5-10 mm larger than the diameter of the bar stock, and the depth of the blind hole is 0.25-0.3 times the length of the bar stock.

[0053] Furthermore, the wall thickness of the collar is 0.4 to 0.6 times the diameter of the bar stock, and the material used for the collar is ordinary mold steel or structural steel.

[0054] In step 5, all punches are 300mm high and have a frustum structure. The small punch has a diameter of 200mm at the small end and 300mm at the large end; the medium punch has a small end that is 10-30mm smaller than the large end of the small punch, and a large end that is 100-120mm larger than the small end; the large punch has a small end that is 10-30mm smaller than the large end of the medium punch, and a large end that is 100-120mm larger.

[0055] Furthermore, the punch is made of hot work die steel.

[0056] The rough shape in step 7 is a simulated and optimized design with a uniform deformation distribution. To ensure that the forging is completely filled, the length of the rough shape is 110 mm smaller than that of the pre-forging part, and the width is 120 mm smaller than that of the pre-forging part. The deformation of the rough shape during the pre-forging process is in the range of 15% to 30%.

[0057] The pre-forging die in step 8 is designed and manufactured according to the pre-forging part. The pre-forging part has a simpler structure than the final forging part, and the short ribs are removed. The web thickness is 1.4 to 2.0 times that of the final forging part, the outer structure of the forging part is 40 to 60 mm smaller on one side than the final forging part, the height of the high ribs in the forging part is 0.6 to 0.8 times that of the final forging part, the side draft angle of the pre-forging part is 3° greater than that of the final forging part, and the radius of the concave corner of the rib bottom is 80 to 100 mm.

[0058] Furthermore, the cavity of the pre-forging die is 1.006 times the outer shape of the pre-forging part. The pre-forging die corresponding to the inner hole area of ​​the pre-forging part is designed with an irregular shape, such as... Figure 1 As shown.

[0059] The inner cavity area of ​​the lower mold mainly consists of a ramp surface X2, a plane X1, and a transition arc surface. The height at which the ramp surface X2 intersects the cavity is h2, and the height at which it intersects the plane X1 is h1. Figure 2 As shown. The widths of X2, XL1, XL2, XL3, and XL4, vary at different positions in the mold, with XL2, XL3, and XL4 being the same, approximately 1.6 to 2.0 times that of XL1.

[0060] The inner cavity area of ​​the upper mold is mainly composed of ramp surfaces S3 and S2 and the impact surface S1. The height at which ramp surface S3 intersects with the cavity is h3, and the height at which it intersects with the cavity is h4. The widths SL1, SL2, SL3, and SL4 of S3 vary at different positions in the mold, with SL2, SL3, and SL4 being the same, ranging from 1.6 to 2.0 times the width of SL1. The width of ramp surface S2 is SL5, which is 2.0 to 2.4 times the width of SL1.

[0061] Furthermore, h1 is 7–10 mm, h2 is 14–20 mm, h3 is 7–10 mm, h4 is 14–20 mm; XL1 is 50–80 mm, and SL2 is 90–120 mm.

[0062] This invention provides a method for forging an integral frame-type titanium alloy, comprising:

[0063] Step 1: Material preparation. First, machine both ends of the raw material bar with a diameter of 450mm and a length of 2400mm to ensure that they are perpendicular to the bar. Round the edges of both ends to R15mm.

[0064] Step 2: The bar is then heated to the forging temperature in a furnace. The heated bar is placed on an anvil for upsetting. For bars with a height-to-diameter ratio greater than 4.5, a collar is attached to one end of the bar during upsetting, causing deformation in the area outside the collar, achieving localized upsetting and preventing double bulging. The collar is then removed, and a second upsetting is performed. The upsetting size is a forging blank with a diameter of 550mm and a length of 1500mm. During this process, the forging temperature is 940℃~975℃. The collar material is ordinary hot work die steel.

[0065] Step 3: After upsetting, the bar stock is reheated in the furnace. The heated billet is flattened and shaped to 800mm × 240mm × ~1600mm. Then, the billet is upset along the diagonal, pressing the metal at the four corners into the thickness direction of the billet, pressing down about 100mm at each corner. This becomes the first intermediate billet, with the length direction of the bar stock remaining unchanged from the length direction of the billet.

[0066] Step 4: After the first intermediate billet has been forged and shaped, it is reheated in the furnace, while punches 11, 12, 21, 22, 31 and 32 are heated at a temperature of 150-250℃.

[0067] Two heated punches, 11 and 12, are placed on the first intermediate billet for punching. The punches are positioned at the center of the width of the first intermediate billet, symmetrically placed along its length with a center-to-center distance of 640 mm. After punching, punches 11 and 12 are replaced with punches 21 and 22 for the first punch reaming. After this, punches 21 and 22 are replaced with punches 31 and 32 for the second punch reaming. After punching and two reaming operations, the second intermediate billet is obtained, with a length of approximately 1950 mm, a width of approximately 1020 mm, and a thickness of 240 mm.

[0068] Step 5: Reheat the second intermediate billet. Widen the heated second intermediate billet, drawing it lengthwise along the width of the rough billet to 1520mm and the thickness to 170mm. Then, draw it lengthwise to 130mm and the length to 2500mm, obtaining the third intermediate billet. During this process, the forging temperature is 940℃~975℃.

[0069] Step 6: Reheat the third intermediate billet in the furnace. The heated third intermediate billet is then drawn again, extending the middle section along its length. The 1700mm length of the billet is drawn to 2550mm, with the drawn portion having a thickness of 85mm. The overall length of the billet is approximately 3360mm. The forging temperature is 940℃~975℃, completing the rough forging process.

[0070] The rough shape was then air-cooled to room temperature. Surface defects were then removed by polishing.

[0071] Step 7: Heat the rough shape; simultaneously heat the pre-forging die. After heating, perform pre-forging; the first heat is applied until the vertical distance to the upper and lower dies is 32mm. After forging, the rough shape is air-cooled to room temperature, and the burrs and connecting skin are removed by machining. The connecting skin is the 800mm diameter area in the middle of the inner hole of the rough shape, which is removed by grinding to eliminate surface defects. The rough shape is heated again, and after heating, a second pre-forging is performed, with the vertical distance to the upper and lower dies being 12mm. The forging temperature is 940℃~975℃, and the pressing speed is 4~6mm / s.

[0072] Step 8: Air-cool the rough shape to room temperature, then remove the burrs and skin from the pre-forged part by machining, and use grinding to remove surface defects of the rough shape.

[0073] Step 9: Heat the rough shape; simultaneously heat the final forging die. After heating, perform pre-forging; press the die to a vertical distance of 25mm between the upper and lower dies. After forging, lift the rough shape and air-cool it to room temperature. Machine-remove the burrs and lining skin from the forging, leaving a 25mm lining skin. Grind to remove surface defects from the rough shape. Heat the rough shape again, and after heating, perform a second die forging, pressing it to the dimensions required by the drawing. The forging temperature is 940℃~975℃, and the pressing speed is 4~6mm / s.

[0074] Step 10: Air-cool the rough shape to room temperature, then remove the burrs and lining of the forging by machining, and use grinding to eliminate surface defects of the rough shape.

[0075] Step 11: Heat treat the forging.

[0076] The collar in step 1 is a cylindrical structure with a blind hole at one end. The diameter of the blind hole is 5-10 mm larger than the diameter of the bar stock, and the depth of the blind hole is 0.25-0.3 times the length of the bar stock.

[0077] Furthermore, the wall thickness of the collar is 0.4 to 0.6 times the diameter of the bar stock, and the material used for the collar is ordinary mold steel or structural steel.

[0078] In step 4, all punches are 300mm high. Punches 11 and 12 are identical in size and are frustum structures, with a diameter of 200mm at the small end and 300mm at the large end. Punches 21 and 22 are identical in size and are frustum structures, with the small end being 10-30mm smaller than the large end of punches 11 and 12, and the large end being 100-120mm larger than the small end. Punches 31 and 32 are identical in size and are frustum structures, with the small end being 10-30mm smaller than the large end of punches 21 and 22, and the large end being 100-120mm larger than the small end.

[0079] Furthermore, the punch is made of hot work die steel.

[0080] The rough shape in step 6 is a simulated and optimized design with a uniform deformation distribution. To ensure that the forging is completely filled, the length of the rough shape is 110 mm smaller than that of the pre-forging part, and the width is 120 mm smaller than that of the pre-forging part. The deformation of the rough shape during the pre-forging process is in the range of 15% to 30%.

[0081] The pre-forging die in step 7 is designed and manufactured according to the pre-forging part. The pre-forging part has a simpler structure than the final forging part, and the short ribs are removed. The web thickness is 1.4 to 2.0 times that of the final forging part, the outer side structure of the forging part is 40 to 60 mm smaller on one side than the final forging part, the height of the high ribs in the forging part is 0.6 to 0.8 times that of the final forging part, the side draft angle of the pre-forging part is 3° greater than that of the final forging part, and the radius of the concave corner of the rib bottom is 80 mm.

[0082] Furthermore, the cavity of the pre-forging die is 1.006 times the outer shape of the pre-forging part. The pre-forging die corresponding to the inner hole area of ​​the pre-forging part is designed with an irregular shape, such as... Figure 1 As shown.

[0083] The inner cavity area of ​​the lower mold mainly consists of a sloping surface X2, a plane X1, and a transition arc surface, such as... Figure 2 As shown, the height of the intersection of the ramp surface X2 and the cavity is h2, and the height of the intersection of the ramp surface X2 and the plane X1 is h1. The widths XL1, XL2, XL3, and XL4 of X2 vary at different positions in the mold, while XL2, XL3, and XL4 are the same, approximately 1.6 to 2.0 times the width of XL1.

[0084] The inner cavity area of ​​the upper mold is mainly composed of ramp surfaces S3 and S2 and the impact surface S1. The height at which ramp surface S3 intersects with the cavity is h3, and the height at which it intersects with ramp surface S3 is h4. Figure 3 As shown. The widths SL1, SL2, SL3, and SL4 of S3 vary at different positions in the mold, with SL2, SL3, and SL4 having the same width, which is 1.6 to 2.0 times the width of SL1. The width of the ramp surface S2 is SL5, which is 2.0 to 2.4 times the width of SL1.

[0085] Furthermore, h1 is 7–10 mm, h2 is 14–20 mm, h3 is 7–10 mm, h4 is 14–20 mm; XL1 is 50–80 mm, and SL2 is 90–120 mm.

[0086] The length of the upsetting bar stock is 0.9 to 1.0 times the length of the first intermediate billet;

[0087] The length of the first intermediate billet is 0.45 to 0.48 times the length and width of the pre-forging, and the width of the first intermediate billet is 0.47 to 0.5 times the width of the pre-forging.

[0088] The width of the third intermediate billet is 0.95 to 1.0 times the width of the rough shape; the length of the third intermediate billet is 0.7 to 0.75 times the width of the rough shape.

[0089] During forging, the two steps of the upper punch can achieve zoned forging and reduce forging pressure; as the distance between the upper and lower punches decreases, part of the metal on the blank corresponding to the inner hole of the pre-forged part is squeezed into the mold cavity by the inclined surface under the action of the upper and lower punches.

[0090] Example 1

[0091] Taking a certain type of aircraft integral frame forging as an example, the forging material is titanium alloy, and the forging projected area is 2.8m². 2 The forging has an outline dimension of 3800mm × 1800mm × 168mm. It is a frame-like structure with high ribs, and has two through holes arranged along its elongation direction. The through holes are 1120mm long and 950mm wide, with a total area of ​​approximately 1m². 2 Due to the influence of the large-area inner hole, the cross-sectional ratio of the forging reaches 10.4:1.

[0092] The forging method of the present invention includes the following steps:

[0093] Step 1: Material preparation. First, machine both ends of the raw material bar with a diameter of 450mm and a length of 2400mm to ensure that they are perpendicular to the bar. Round the edges of both ends to R15mm.

[0094] Step 2: Then heat to 950°C in a heating furnace.

[0095] Step 3: Place the heated bar stock on the anvil for upsetting. For bars with a height-to-diameter ratio greater than 4.5, attach a collar to one end of the bar stock during upsetting. This causes deformation in the area outside the collar, achieving localized upsetting and preventing double bulging. Then remove the collar and continue upsetting. The upsetting dimensions are for a forging blank with a diameter of 550mm and a length of 1500mm. The collar material is ordinary hot work die steel.

[0096] Step 4: After upsetting, the bar stock is reheated in the furnace. The heated billet is flattened and shaped to 800mm × 240mm × ~1600mm. Then, the billet is upset along the diagonal, pressing the metal at the four corners into the thickness direction of the billet, pressing down about 100mm at each corner. This becomes the first intermediate billet, with the length direction of the bar stock remaining unchanged from the length direction of the billet.

[0097] Step 5: After the first intermediate billet has been forged and shaped, it is reheated in the furnace, while punches 11, 12, 21, 22, 31, and 32 are heated at a temperature of 150-250℃.

[0098] The first intermediate billet is placed flat on the anvil. Two heated punches, 11 and 12, are placed on the billet for punching. The punches are positioned at the center of the billet's width, symmetrically spaced 640mm apart along its length. After punching, punches 11 and 12 are replaced with punches 21 and 22 for the first punch reaming. After this, punches 21 and 22 are replaced with punches 31 and 32 for the second punch reaming. After punching and the two reaming operations, the second intermediate billet is obtained, with a length of approximately 1950mm, a width of approximately 1020mm, and a thickness of 240mm.

[0099] Step 6: Reheat the second intermediate billet in the furnace to a temperature of 950℃. Widen the heated second intermediate billet and elongate it along the width dimension of the billet, elongating the billet to a width of 1520mm and a thickness of 170mm. Then elongate the billet along the length direction, elongating the billet to a thickness of 130mm and a length of 2500mm, to obtain the third intermediate billet.

[0100] Step 7: Reheat the third intermediate billet in the furnace to a temperature of 950℃. Then, draw the heated third intermediate billet again, extending the middle section along its length. Lengthen the 1700mm section of the billet to 2550mm, with the drawn portion having a thickness of 85mm. The overall length of the billet is approximately 3360mm.

[0101] The rough shape was then air-cooled to room temperature. Surface defects were then removed by polishing.

[0102] Step 8: Heat the rough shape to 950℃; simultaneously heat the pre-forging die. After heating, perform pre-forging; the first heat presses the rough shape to a vertical distance of 32mm between the upper and lower dies. After forging, lift the rough shape and air-cool it to room temperature. Machine-machine to remove burrs and burrs from the forging. The burrs are the 800mm diameter area in the center of the rough shape's inner hole; surface defects are removed by grinding. Heat the rough shape again, and after heating, perform a second pre-forging, pressing the rough shape to a vertical distance of 12mm between the upper and lower dies. The pressing speed is 6mm / s.

[0103] Step 9: Air-cool the rough shape to room temperature, then remove the burrs and lining of the pre-forged part by machining, and use grinding to remove surface defects of the rough shape.

[0104] Step 10: Heat the rough shape to 950℃; simultaneously heat the final forging die to 350℃. After heating, perform pre-forging; the first forging presses the rough shape to a vertical distance of 25mm between the upper and lower dies. After forging, air-cool the rough shape to room temperature, then machine to remove burrs and burrs, leaving a 25mm burr. Grind to remove surface defects. Reheat the rough shape, and after heating, perform a second forging press to the dimensions specified in the drawing. The pressing speed is 6mm / s.

[0105] Step 11: Air-cool the rough shape to room temperature, then remove the burrs and lining of the forging by machining, and use grinding to remove surface defects of the rough shape.

[0106] Step 12: Heat treat the forging.

[0107] The collar in step 1 is a cylindrical structure with a blind hole at one end. The diameter of the blind hole is 5-10 mm larger than the diameter of the bar stock, and the depth of the blind hole is 0.25-0.3 times the length of the bar stock.

[0108] Furthermore, the wall thickness of the collar is 0.4 to 0.6 times the diameter of the bar stock, and the material used for the collar is ordinary mold steel or structural steel.

[0109] In step 5, all punches are 300mm high. Punches 11 and 12 are identical in size and are frustum structures, with a diameter of 200mm at the small end and 300mm at the large end. Punches 21 and 22 are identical in size and are frustum structures, with the small end being 10-30mm smaller than the large end of punches 11 and 12, and the large end being 100-120mm larger than the small end. Punches 31 and 32 are identical in size and are frustum structures, with the small end being 10-30mm smaller than the large end of punches 21 and 22, and the large end being 100-120mm larger than the small end.

[0110] Furthermore, the punch is made of hot work die steel.

[0111] The rough shape in step 7 is a simulated and optimized design with a uniform deformation distribution. To ensure that the forging is completely filled, the length of the rough shape is 110 mm smaller than that of the pre-forging part, and the width is 120 mm smaller than that of the pre-forging part. The deformation of the rough shape during the pre-forging process is in the range of 15% to 30%.

[0112] The pre-forging die in step 8 is designed and manufactured according to the pre-forging part. The pre-forging part has a simpler structure than the final forging part, and the short ribs are removed. The web thickness is 1.5 times that of the final forging part, the outer structure of the forging part is 55mm smaller on one side than the final forging part, the height of the high ribs in the forging part is 0.8 times that of the final forging part, the side draft angle of the pre-forging part is 3° larger than that of the final forging part, and the radius of the concave corner of the rib bottom is 80mm.

[0113] Furthermore, the pre-forging die cavity is 1.006 times the outer shape of the pre-forging part. The pre-forging die corresponding to the inner hole area of ​​the pre-forging part is designed with an irregular shape. The inner hole area of ​​the lower die mainly consists of a ramp surface, a plane, and a transition arc surface. The height of the ramp surface intersecting the cavity is 20mm, and the height of the ramp surface intersecting the plane is 10mm. The height difference between the ramp surface and the plane is transitioned by an arc. The width of the ramp surface inside the two through holes is 80mm, and the width of the ramp surface at other locations is 135mm.

[0114] The inner cavity area of ​​the upper mold mainly consists of ramp surfaces and planes. The height at which the first ramp surface on the inner side of the two through holes intersects with the cavity is 20mm, and the height at the intersection of the two ramp surfaces is 10mm. The width of the first ramp surface on the inner side of the two through holes is 120mm, and the width of the first ramp surface at other locations is 220mm. The width of the second ramp surface is 280mm.

[0115] The forgings obtained using the above method meet the dimensions, shape, and performance requirements of the drawings. The billet preparation method, employing large-diameter bars, involves upsetting with rings and punching holes, pre-distributing the material and deformation required for the rough forging process. This enables the production of large integral frame forgings using bar stock, improving material utilization, shortening the raw material procurement cycle, thereby increasing forging production efficiency, reducing raw material procurement costs, and lowering the overall production cost of the forgings.

Claims

1. A forging method for producing integral frame forgings using bar stock, characterized in that, include: Material feeding; The bar stock is placed on the anvil and upset along the height direction; After the upsetting is completed, the bar stock is reheated in the furnace, then flattened and forged to obtain a blank. The blank is then upset along the diagonal to compress the metal at the four corners and increase the local thickness of the blank, finally obtaining the first intermediate billet. Place the first intermediate blank flat on the hammer anvil, place the two heated small punches on the first intermediate blank to punch holes. After punching, replace the small punches with medium punches and perform the first punching hole enlargement to obtain the second intermediate blank with two symmetrical through holes. The second intermediate billet is widened and lengthened to obtain the third intermediate billet; The third intermediate billet is partially elongated, with the elongation area being the middle area along the length direction, to complete the rough forging. The rough shape is pre-forged and final-forged to obtain the forging; The upper and lower dies of the pre-forging are equipped with upper and lower punches corresponding to the symmetrical through holes; The upper punch consists of two square platforms with different slopes and a large arc transition. The top of the upper platform is removed, and the connecting surfaces of the upper and lower platforms completely overlap. The lower punch includes a square boss and a square platform with a slope. The square boss and the square platform with a slope transition with an arc.

2. The method according to claim 1, characterized in that, The width of the inclined surface XL1 near the middle of the lower punch is smaller than the widths of the other three inclined surfaces XL2, XL3, and XL4; XL2, XL3, and XL4 are the same, being 1.6 to 2.0 times XL1. The width of the inclined surface SL1 near the middle of the lower platform of the upper punch is smaller than the widths of the other three inclined surfaces SL2, SL3, and SL4; the widths of SL2, SL3, and SL4 are the same, which are 1.6 to 2.0 times SL1. The width of the four inclined surfaces of the lower punch is smaller than the width of the corresponding inclined surface of the lower platform of the upper punch; the width of the four inclined surfaces of the upper platform of the upper punch is the same, which is 2.0 to 2.4 times SL1.

3. The method according to claim 1, characterized in that, Pre-forging, including: First heat: Press until the vertical distance between the upper and lower dies is 32mm; after forging, the rough shape is raised and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining; Second heat: Press until the upper and lower molds are to the dimensions required by the drawing; The forging temperature is 940℃~975℃, and the pressing speed is 4~6mm / s.

4. The method according to claim 1, characterized in that, The first intermediate billet is punched and enlarged to obtain a second intermediate billet with two symmetrical through holes, comprising: For any through hole, place the first intermediate blank flat on the hammer anvil, place the two heated punches on the first intermediate blank, and punch the hole. The punches are placed at the center of the width of the first intermediate blank, and symmetrically placed 320mm away from the center in the length direction. After punching is completed, the hole is enlarged twice more.

5. The method according to claim 1, characterized in that, The bar stock is placed on a hammer anvil and upset along its height, including: For bar stock with a height-to-diameter ratio greater than 4.5, a collar is attached to one end of the bar stock during upsetting, so that the area of ​​the bar stock outside the collar deforms, achieving local upsetting while ensuring that the height-to-diameter ratio is less than 4.

5. Remove the collar and proceed with the second upsetting; During this process, the forging temperature is 940℃~975℃.

6. The method according to claim 5, characterized in that, The collar is a cylindrical structure with a blind hole at one end. The diameter of the blind hole is 5-10 mm larger than the diameter of the bar stock, and the depth of the blind hole is 0.25-0.3 times the length of the bar stock.

7. The method according to claim 5, characterized in that, The wall thickness of the collar is 0.4 to 0.6 times the diameter of the bar stock, and the material used for the collar is ordinary mold steel or structural steel.

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