Forging method for forging integral frame forge piece by adopting bar material

Abstract

The invention belongs to the field of forging hot working, and particularly relates to a forging method for forging an integral frame forge piece by adopting a bar material. The method comprises the following steps: blanking; the bar is placed on a hammer anvil to be subjected to upsetting in the height direction; heating the upset bar in a furnace, flattening and forging to obtain a rough blank, upsetting the rough blank along diagonal lines to extrude metal at four corners to increase the local thickness of the rough blank, and finally obtaining a first intermediate blank; punching and chambering the first intermediate blank to obtain a second intermediate blank with two symmetrical through holes; the second intermediate billet is broadened and drawn out, and a third intermediate billet is obtained; the third intermediate blank is subjected to local drawing-out, the drawing-out area is a middle area in the length direction, and rough shape forging is completed; and the rough shape is subjected to pre-forging and finish-forging, and a forge piece is obtained.

Description

Technical Field

[0001] The invention belongs to the field of forging hot processing, and in particular relates to a forging method for forging an integral frame forging by using a bar material. Background Art

[0002] The integral frame forgings for a certain type of aircraft are made of titanium alloy. The forging structure has the characteristics of large outline, large projection area, and thin belly plate. The forging is a bilaterally symmetrical structure with two through holes arranged in the middle of the left and right sides, resembling a glasses frame. The maximum and minimum cross-sectional dimensions of the forging are quite different, with a cross-sectional ratio of 10.4:1, and the forging structure is complex.

[0003] Due to the large weight and projection area of ​​the forgings and the complex structure, the existing raw material bars cannot meet the requirements for forging forming. Therefore, the forging methods currently used are all to use rectangular billets of equal thickness as raw materials, and then use molds or free forging methods to thin the skin (such as patent number CN105215240.A, patent number 113245492.A), and then use special molds made according to the shape and size of the forgings to perform pre-forging and final forging operations to complete the forging forming. In the implementation process of this method, whether it is using a mold or free forging, the main method is to thin the skin. The metal of the skin needs to be removed, the raw material consumption is large, and as the thickness of the skin decreases, the deformation resistance increases sharply, and the demand for equipment tonnage also increases. At the same time, the price of sheet metal is much higher than the price of bar stock, so the production cost of forgings is very high. Summary of the invention

[0004] The purpose of the present invention is to propose a forging method for producing an integral frame, wherein the raw material is a commonly used existing bar material, and a special blank making tool and forging method are used to reduce the consumption of raw materials and the cost of raw materials while ensuring the forging forming. At the same time, the uniformity of the forging deformation of the forging is improved, thereby ensuring the qualified rate.

[0005] Technical solution:

[0006] Provided is a forging method for forging an integral frame forging using bar stock, comprising:

[0007] Cutting materials;

[0008] The bar is placed on the hammer anvil for upsetting in the height direction;

[0009] The bar material after upsetting is returned to the furnace for heating, and then flattened and forged to obtain a blank, and then the blank is upset along the diagonal line to squeeze the metal at the four corners to increase the local thickness of the blank, and finally the first intermediate blank is obtained;

[0010] Punching and expanding the first intermediate blank to obtain a second intermediate blank having two symmetrical through holes;

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

[0012] The third intermediate billet is partially stretched, and the stretching area is the middle area along the length direction, so as to complete the rough forging;

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

[0014] Furthermore, the upper and lower dies of the pre-forging are both provided with an upper punch and a lower punch corresponding to the symmetrical through holes;

[0015] Among them, the upper punch is composed of two square platforms with different slopes and large arc transitions. 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 an slope; there is an arc transition between the square boss and the square platform with an slope.

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

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

[0018] The widths of the four inclined surfaces of the lower punch are all smaller than the corresponding inclined surface widths of the lower platform of the upper punch;

[0019] The width of the four slope surfaces of the upper platform of the upper punch is the same, which is 2.0 to 2.4 times SL1.

[0020] Further, pre-forging, including:

[0021] First fire: press until the vertical distance between the upper and lower dies is 32mm; after forging, lift the rough-shaped pad and air cool to room temperature, and machine to remove the burrs and skin of the forging;

[0022] Second fire: press the upper and lower molds to the required size of the drawing;

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

[0024] Further, the first intermediate blank is punched and expanded to obtain a second intermediate blank having two symmetrical through holes, comprising:

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

[0026] After punching is completed, punch and expand the hole twice.

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

[0028] For bars with a height-to-diameter ratio greater than 4.5, a collar is placed on one end of the bar during upsetting, so that the area outside the collar deforms to achieve local upsetting and ensure that the height-to-diameter ratio is less than 4.5.

[0029] Remove the collar and perform a 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 rod, and the depth of the blind hole is 0.25 to 0.3 times the length of the rod.

[0032] Furthermore, the wall thickness of the sleeve is 0.4 to 0.6 times the diameter of the bar, and the material of the sleeve is ordinary die steel or structural steel.

[0033] Beneficial effects: The forgings obtained by this method have greatly improved the utilization rate of forging materials, and the qualified rate of forgings is high and the quality of forgings is stable. Punches, pre-forging dies and final forging dies are all made of hot working die steel. The beneficial effects of the present invention are that the special punches and special pre-forging dies are used to solve the problem of filling the outer ribs when producing integral frame forgings from bars, improve the qualified rate of forgings, avoid the problem of forgings being scrapped due to lack of meat or clamping, improve the qualified rate of forgings and product stability, and at the same time increase the selection range of raw materials for forgings and reduce the production cost of forgings. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0036] Figure 3 It is a front view of the pre-forging upper mold cavity of the present invention. DETAILED DESCRIPTION

[0037] The present invention provides a method for forging an integral frame titanium alloy, comprising:

[0038] For cutting, first machine both end faces 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 to forging temperature in a heating furnace.

[0040] Step 3: Place the heated bar on the hammer anvil for upsetting. For bars with a height-to-diameter ratio greater than 4.5, a collar is placed on one end of the bar during upsetting to deform the area outside the collar, achieve local upsetting, and avoid double upsetting. Then remove the collar and perform a second upsetting. During this process, the forging temperature is 940°C to 975°C, and the collar material is ordinary hot working die steel.

[0041] Step 4: After upsetting, the bar is returned to the furnace for heating, the heated forging blank is flattened and forged into a square, and then the blank is upset along the diagonal line to squeeze the metal at the four corners to the thickness direction of the blank. This becomes the first intermediate blank, and the length direction of the bar remains the same as the length direction of the blank.

[0042] Step 5: After the forging square is shaped, the first intermediate billet is returned to the furnace for heating, and six punches are heated at the same time, namely, two small punches, two medium punches and two large punches.

[0043] Place the first intermediate blank flat on the hammer anvil, place the heated small punch on the first intermediate blank, and place the punch at the center of the width of the first intermediate blank. Two small punches are symmetrically placed at a center distance of 640 mm in the length direction, and punch. After punching, replace the small punch with a medium punch and perform the first punch expansion. After completion, replace the medium punch with a large punch and perform the second punch expansion. After punching and two expansions, the second intermediate blank is obtained.

[0044] Step 6: Return the second intermediate billet to the furnace for heating. Widen the heated second intermediate billet, lengthen it along the width of the blank, and then lengthen it along the length direction to obtain the third intermediate billet.

[0045] Step 7: Return the third intermediate billet to the furnace for heating. The heated third intermediate billet is stretched again, and the stretching area is the middle area along the length direction. The middle area of ​​the blank is stretched to complete the blank forging.

[0046] The rough-shaped pad is lifted and air-cooled to room temperature, and then the rough-shaped surface defects are eliminated by grinding.

[0047] Step 8: Heat the rough shape; heat the pre-forging die at the same time. After heating, pre-forge; press the first fire until the vertical distance to the upper and lower die bearing surfaces is 25-40mm. After forging, the rough shape is padded and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining, and the surface defects of the rough shape are eliminated by grinding. Heat the rough shape again, and after heating, pre-forge the second fire, and press the second fire until the vertical distance to the upper and lower dies is 8-15mm. Among them, the pressing speed is 4-6mm / s.

[0048] Step 9: The rough-shaped pad is air-cooled to room temperature, and then the burrs and skin of the pre-forged part are removed by machining, and the rough-shaped surface defects are eliminated by grinding.

[0049] Step 10: Heat the rough shape; heat the final forging die at the same time. After heating, pre-forge; press the first fire until the vertical distance between the upper and lower dies is 10-22mm. After forging, the rough shape is padded and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining, leaving 10-22mm of skin, and the surface defects of the rough shape are eliminated by grinding. Heat the rough shape again, and after heating, perform the second die forging fire, and press it to the size required by the drawing. Among them, the pressing speed is 4-6mm / s.

[0050] Step 11: The rough-shaped pad is air-cooled to room temperature, and then the burrs and skin of the forging are removed by machining, and the rough-shaped surface defects are eliminated by grinding.

[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 to 10 mm larger than the diameter of the rod, and the depth of the blind hole is 0.25 to 0.3 times the length of the rod.

[0053] Furthermore, the wall thickness of the sleeve is 0.4 to 0.6 times the diameter of the bar, and the material of the sleeve is ordinary die steel or structural steel.

[0054] The punches in step 5 are all 300mm high and have a truncated cone structure. The diameter of the small end of the truncated cone of a small punch is 200mm, and the diameter of the large end is 300mm; the small end of a medium punch is 10-30mm smaller than the large end of the small punch, and the diameter of the large end is 100-120mm larger than the small end; the diameter of the small end of a large punch is 10-30mm smaller than the large end of a medium punch, and the diameter of the large end is further increased by 100-120mm.

[0055] Furthermore, the raw material selected for the punch is hot working die steel.

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

[0057] The pre-forging die in step 8 is designed and manufactured according to the pre-forging. The pre-forging is simpler in structure than the final forging, and the short ribs are removed. The web thickness is 1.4 to 2.0 times that of the final forging, the outer side structure of the forging is 40 to 60 mm smaller than the final forging on one side, the height of the high rib of the forging is 0.6 to 0.8 times that of the final forging, the side die draft angle of the pre-forging is 3° larger than that of the final forging, and the radius of the concave fillet at the bottom of the rib 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. The die of the pre-forging die corresponding to the inner hole area of ​​the pre-forging is designed to be special-shaped, such as Figure 1 shown.

[0059] The inner hole area of ​​the lower die is mainly composed of a slope surface X2, a plane X1 and a transition arc surface. The height of the slope surface X2 intersecting with the cavity is h2, and the height of the slope surface X2 intersecting with the plane X1 is h1. Figure 2 The width of X2, XL1, XL2, XL3, and XL4, varies at different positions of the mold, among which XL2, XL3, and XL4 are the same, about 1.6 to 2.0 times that of XL1.

[0060] The inner hole area of ​​the upper die is mainly composed of the slope surface S3, S2 and the impact surface S1. The height of the intersection of the slope surface S3 and the cavity is h3, and the height of the intersection with the slope surface S3 is h4. The widths SL1, SL2, SL3, and SL4 of S3 are different at different positions of the mold, among which SL2, SL3, and SL4 are the same, which is 1.6 to 2.0 times of SL1. The width of the slope surface S2 is SL5, and SL5 is 2.0 to 2.4 times of SL1.

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

[0062] The present invention provides a method for forging an integral frame titanium alloy, comprising:

[0063] Step 1: Cutting, first machine both end faces of the raw material bar with a diameter of 450mm and a length of 2400mm to ensure that it is perpendicular to the bar, and round the edges and corners of both ends to R15mm.

[0064] Step 2: Then heat to forging temperature in a heating furnace. Place the heated bar on the hammer anvil for upsetting. For bars with a height-to-diameter ratio greater than 4.5, a collar is placed on one end of the bar during upsetting to deform the area outside the collar, achieve local upsetting, and avoid double drumming. Then remove the collar and perform a second upsetting. The upsetting size is a forging blank with a diameter of 550 mm and a length of 1500 mm. During this process, the forging temperature is 940°C to 975°C. The collar material is ordinary hot working die steel.

[0065] Step 3: After upsetting, the bar is returned to the furnace for heating, and the heated forging blank is flattened and forged into a square, and shaped to 800mm×240mm×~1600mm, and then the blank is upset along the diagonal line, and the metal at the four corners is squeezed to the thickness direction of the blank, and each corner is pressed down about 100mm. It becomes the first intermediate blank, and the length direction of the bar remains the same as the length direction of the blank.

[0066] Step 4: The first intermediate billet after forging and shaping is returned to the furnace for heating, and punches 11, 12, 21, 22, 31 and 32 are heated at the same time, and the heating temperature is 150-250°C.

[0067] Place the two heated punches 11 and 12 on the first intermediate billet for punching. The punches are placed at the center of the width of the first intermediate billet, and are symmetrically placed at a center distance of 640 mm in the length direction. After punching is completed, replace punches 11 and 12 with punches 21 and 22 for the first punch expansion. After completion, replace punches 21 and 22 with punches 31 and 32 for the second punch expansion. After punching and two expansions are completed, the second intermediate billet is obtained. The length of the forging billet is about 1950 mm, the width is about 1020 mm, and the thickness is 240 mm.

[0068] Step 5: Return the second intermediate billet to the furnace for heating. Widen the heated second intermediate billet and stretch it along the width of the blank. The width of the blank is stretched to 1520mm and the thickness of the blank is 170mm. Then stretch the blank along the length direction. The thickness of the blank is 130mm and the length of the blank is 2500mm to obtain the third intermediate billet. In this process, the forging temperature is 940℃~975℃.

[0069] Step 6: Return the third intermediate billet to the furnace for heating. The heated third intermediate billet is stretched again, and the stretching area is the middle area along the length direction. The middle length of the blank is 1700mm, and the blank is stretched to 2550mm. The thickness of the stretched part of the blank is 85mm, and the overall length of the blank is about 3360mm. Among them, the forging temperature is 940℃~975℃, and the blank forging is completed.

[0070] The rough-shaped pad is lifted and air-cooled to room temperature, and then the rough-shaped surface defects are eliminated by grinding.

[0071] Step 7: Heat the rough shape; heat the pre-forging die at the same time. Pre-forging is performed after heating is completed; the first fire is pressed until the vertical distance between the upper and lower dies is 32mm. After forging, the rough shape is padded and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining. The skin is the area with a diameter of 800mm in the middle of the inner hole of the rough shape. The surface defects of the rough shape are eliminated by grinding. Heat the rough shape again, and pre-forge the second fire after heating is completed. The second fire is pressed until the vertical distance between the upper and lower dies is 12mm. Among them, the forging temperature is 940℃~975℃, and the pressing speed is 4~6mm / s.

[0072] Step 8: The rough-shaped pad is air-cooled to room temperature, and then the burrs and skin of the pre-forging are removed by machining, and the rough-shaped surface defects are eliminated by grinding.

[0073] Step 9: Heat the rough shape; heat the final forging die at the same time. After heating, pre-forging is carried out; the first fire is pressed until the vertical distance between the upper and lower dies is 25mm. After forging, the rough shape is padded and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining, leaving 25mm of skin, and the surface defects of the rough shape are eliminated by grinding. Heat the rough shape again, and after heating, perform the second die forging, and press it to the size required by the drawing. Among them, the forging temperature is 940℃~975℃, and the pressing speed is 4~6mm / s.

[0074] Step 10: The rough-shaped pad is air-cooled to room temperature, and then the burrs and skin of the forging are removed by machining, and the rough-shaped surface defects are eliminated by grinding.

[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 to 10 mm larger than the diameter of the rod, and the depth of the blind hole is 0.25 to 0.3 times the length of the rod.

[0077] Furthermore, the wall thickness of the sleeve is 0.4 to 0.6 times the diameter of the bar, and the material of the sleeve is ordinary die steel or structural steel.

[0078] The punches in step 4 are all 300 mm in height. Punches 11 and 12 are of the same size and are of a truncated cone structure. The diameter of the small end of the truncated cone is 200 mm, and the diameter of the large end is 300 mm. Punches 21 and 22 are of the same size and are of a truncated cone structure. The small end is 10 to 30 mm smaller than the large end of punches 11 and 12, and the diameter of the large end is 100 to 120 mm larger than the small end. Punches 31 and 32 are of the same size and are of a truncated cone structure. The diameter of the small end of the truncated cone is 10 to 30 mm smaller than the large end of punches 21 and 22, and the diameter of the large end is 100 to 120 mm larger than the small end.

[0079] Furthermore, the raw material selected for the punch is hot working die steel.

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

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

[0082] Furthermore, the cavity of the pre-forging die is 1.006 times the outer shape of the pre-forging. The die of the pre-forging die corresponding to the inner hole area of ​​the pre-forging is designed to be special-shaped, such as Figure 1 shown.

[0083] The inner hole area of ​​the lower die is mainly composed of a slope surface X2, a plane X1 and a transition arc surface, such as Figure 2 As shown, the height of the slope surface X2 at the intersection with the cavity is h2, and the height of the slope surface X2 at the intersection with the plane X1 is h1. The widths XL1, XL2, XL3, and XL4 of X2 are different at different positions of the mold, among which XL2, XL3, and XL4 are the same, which are about 1.6 to 2.0 times of XL1.

[0084] The inner hole area of ​​the upper die is mainly composed of the slope surface S3, S2 and the impact surface S1. The height of the intersection of the slope surface S3 and the cavity is h3, and the height of the intersection with the slope surface S3 is h4. Figure 3 As shown. The widths SL1, SL2, SL3, and SL4 of S3 are different at different positions of the mold, among which SL2, SL3, and SL4 have the same width, which is 1.6 to 2.0 times of SL1. The width of the slope surface S2 is SL5, and SL5 is 2.0 to 2.4 times of SL1.

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

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

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

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

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

[0090] Example 1

[0091] Take a certain type of aircraft integral frame forging as an example. The forging material is titanium alloy and the forging projection area is 2.8m 2 The forging has an outline size of 3800mm×1800mm×168mm. The forging is a frame structure with high ribs. There are two through holes arranged in the extension direction. The length of the through hole is 1120mm, the width is 950mm, and the through hole area is about 1m 2 Due to the large inner hole, the ratio of the forging cross section is 10.4:1.

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

[0093] Step 1: Cutting, first machine both end faces of the raw material bar with a diameter of 450mm and a length of 2400mm to ensure that it is perpendicular to the bar, and round the edges and corners of both ends to R15mm.

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

[0095] Step 3: Place the heated bar on the hammer anvil for upsetting. For bars with a height-to-diameter ratio greater than 4.5, a collar is placed on one end of the bar during upsetting to deform the area outside the collar, achieve local upsetting, and avoid double drumming. Then remove the collar and upsetting again. The upsetting size is 550mm in diameter and 1500mm in length. The collar material is ordinary hot working die steel.

[0096] Step 4: After upsetting, the bar is returned to the furnace for heating, and the heated forging blank is flattened and forged into a square, and shaped to 800mm×240mm×~1600mm, and then the blank is upset along the diagonal line, and the metal at the four corners is squeezed to the thickness direction of the blank, and each corner is pressed down by about 100mm. It becomes the first intermediate blank, and the length direction of the bar remains the same as the length direction of the blank.

[0097] Step 5: The first intermediate billet after forging and shaping is returned to the furnace for heating, and punches 11, 12, 21, 22, 31 and 32 are heated at the same time, and the heating temperature is 150-250°C.

[0098] Place the first intermediate billet flat on the hammer anvil, place the two heated punches 11 and 12 on the first intermediate billet for punching. The punches are placed at the center of the width of the first intermediate billet, and are symmetrically placed at a center distance of 640 mm in the length direction. After punching, replace punches 11 and 12 with punches 21 and 22 for the first punch expansion. After completion, replace punches 21 and 22 with punches 31 and 32 for the second punch expansion. After punching and two expansions, the second intermediate billet is obtained. The length of the forging billet is about 1950 mm, the width is about 1020 mm, and the thickness is 240 mm.

[0099] Step 6: The second intermediate billet is returned to the furnace for heating at a temperature of 950°C. The heated second intermediate billet is widened and stretched along the width of the blank to 1520 mm and a thickness of 170 mm. The blank is then stretched along the length direction to 130 mm and a length of 2500 mm, thereby obtaining a third intermediate billet.

[0100] Step 7: The third intermediate billet is returned to the furnace for heating at a temperature of 950°C. The heated third intermediate billet is stretched again, and the stretching area is the middle area along the length direction. The middle length area of ​​the rough billet of 1700mm is stretched to 2550mm, the thickness of the stretched part of the rough billet is 85mm, and the overall length of the rough billet is about 3360mm.

[0101] The rough-shaped pad is lifted and air-cooled to room temperature, and then the rough-shaped surface defects are eliminated by grinding.

[0102] Step 8: Heat the rough shape to 950℃; heat the pre-forging die at the same time. Pre-forge after heating; press the first fire until the vertical distance between the upper and lower dies is 32mm. After forging, the rough shape is padded and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining. The skin is the area with a diameter of 800mm in the middle of the inner hole of the rough shape. The surface defects of the rough shape are eliminated by grinding. Heat the rough shape again, and pre-forge the second fire after heating. The second fire is pressed until the vertical distance between the upper and lower dies is 12mm. Among them, the pressing speed is 6mm / s.

[0103] Step 9: The rough-shaped pad is air-cooled to room temperature, and then the burrs and skin of the pre-forged part are removed by machining, and the rough-shaped surface defects are eliminated by grinding.

[0104] Step 10: Heat the rough shape to 950℃; heat the final forging die to 350℃ at the same time. After heating, pre-forge; press the first fire until the vertical distance between the upper and lower dies is 25mm. After forging, the rough shape is padded and air-cooled to room temperature, and the burrs and skin of the forging are removed by machining, leaving 25mm of skin, and the surface defects of the rough shape are eliminated by grinding. Heat the rough shape again, and after heating, perform the second die forging, and press the second fire to the size required by the drawing. Among them, the pressing speed is 6mm / s.

[0105] Step 11: The rough-shaped pad is air-cooled to room temperature, and then the burrs and skin of the forging are removed by machining, and the rough-shaped surface defects are eliminated by grinding.

[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 to 10 mm larger than the diameter of the rod, and the depth of the blind hole is 0.25 to 0.3 times the length of the rod.

[0108] Furthermore, the wall thickness of the sleeve is 0.4 to 0.6 times the diameter of the bar, and the material of the sleeve is ordinary die steel or structural steel.

[0109] The punches in step 5 are all 300 mm in height. Punches 11 and 12 are of the same size and are of a truncated cone structure. The diameter of the small end of the truncated cone is 200 mm, and the diameter of the large end is 300 mm. Punches 21 and 22 are of the same size and are of a truncated cone structure. The small end is 10 to 30 mm smaller than the large end of punches 11 and 12, and the diameter of the large end is 100 to 120 mm larger than the small end. Punches 31 and 32 are of the same size and are of a truncated cone structure. The diameter of the small end of the truncated cone is 10 to 30 mm smaller than the large end of punches 21 and 22, and the diameter of the large end is 100 to 120 mm larger than the small end.

[0110] Furthermore, the raw material selected for the punch is hot working die steel.

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

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

[0113] Furthermore, the cavity of the pre-forging die is 1.006 times the shape of the pre-forging part. The die corresponding to the inner hole area of ​​the pre-forging part is designed to be special-shaped. The inner hole area of ​​the lower die is mainly composed of a slope surface, a plane and a transition arc surface. The height of the slope surface at the intersection with the cavity is 20mm, and the height of the slope surface at the intersection with the plane is 10mm. The height difference between the slope surface and the plane adopts an arc transition. The width of the slope surface on the inner side of the two through holes is 80mm, and the width of the slope surface at other positions is 135mm.

[0114] The inner hole area of ​​the upper die is mainly composed of sloped surfaces and planes. The height of the first sloped surface on the inner side of the two through holes intersecting with the cavity is 20mm, and the height of the intersection of the two sloped surfaces is 10mm. The width of the first sloped surface on the inner side of the two through holes is 120mm, and the width of the first sloped surface at other locations is 220mm. The width of the second sloped surface is 280mm.

[0115] The size, shape and performance of the die forgings obtained by the above scheme all meet the requirements of the drawings. The blank making method of large-sized bars is adopted, which is upsetting with a sleeve and punching with a punch, and the materials and deformation required for rough-shaped forging die forgings are pre-distributed. The production of large integral frame forgings using bars is realized, the material utilization rate is improved, the raw material procurement cycle is shortened, thereby improving the production efficiency of forgings, reducing the procurement cost of raw materials, and reducing the production cost of forgings.

Claims

1. A forging method for forging an integral frame forging using a bar, characterized in that: include: Cutting materials; The bar is placed on the hammer anvil for upsetting in the height direction; The bar material after upsetting is returned to the furnace for heating, and then flattened and forged to obtain a blank, and then the blank is upset along the diagonal line to squeeze the metal at the four corners to increase the local thickness of the blank, and finally the first intermediate blank is obtained; Punching and expanding the first intermediate blank to obtain a second intermediate blank having two symmetrical through holes; The second intermediate billet is widened and lengthened to obtain a third intermediate billet; The third intermediate billet is partially stretched, and the stretching area is the middle area along the length direction, so as to complete the rough forging; The rough shape is pre-forged and final forged to obtain the forging.

2. The method according to claim 1, characterized in that: The upper and lower dies of the pre-forging are both provided with an upper punch and a lower punch corresponding to the symmetrical through holes; Among them, the upper punch is composed of two square platforms with different slopes and large arc transitions. 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 an slope; there is an arc transition between the square boss and the square platform with an slope.

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

4. The method according to claim 1, characterized in that: Pre-forging, including: First fire: press until the vertical distance between the upper and lower dies is 32mm; after forging, lift the rough-shaped pad and air cool to room temperature, and machine to remove the burrs and skin of the forging; Second fire: press the upper and lower molds to the required size of the drawing; Among them, the forging temperature is 940℃~975℃, and the pressing speed is 4~6mm / s.

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

6. The method according to claim 1, characterized in that The bar is placed on the hammer anvil for upsetting in the height direction, including: For bars with a height-to-diameter ratio greater than 4.5, a collar is placed on one end of the bar during upsetting, so that the area outside the collar deforms to achieve local upsetting and ensure that the height-to-diameter ratio is less than 4.

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

7. The method according to claim 6, characterized in that 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 rod, and the depth of the blind hole is 0.25 to 0.3 times the length of the rod.

8. The method according to claim 6, characterized in that The wall thickness of the collar is 0.4 to 0.6 times the diameter of the bar, and the material used for the collar is ordinary die steel or structural steel.

Images