Forging method of hollow shaft forge piece with flanges at two ends

Abstract

The invention relates to a forging method of a hollow shaft forge piece with flanges at two ends, which belongs to the technical field of forging and comprises the following steps: S1, pretreating a steel ingot; s2, upsetting and punching are conducted; s3, primary reaming is conducted, specifically, the blank obtained after upsetting and punching is heated to 1150-1250 DEG C, heat preservation is conducted for 4-8 h, and an inner hole of the heated blank is expanded; s4, primary drawing-out is conducted, specifically, the blank obtained after primary reaming is conducted is heated to 1000-1200 DEG C, heat preservation is conducted for 4-8 h, and the heated blank is drawn out till the outer diameter of the blank is equal to the outer diameter required by the process of the flange; s5, forging flanges and a concave baffle: heating the blank subjected to primary drawing to 1000-1200 DEG C, preserving heat for 4-8 hours, and then forging the flanges at the two ends and the concave baffle in the middle; and S6, drawing-chambering forging is conducted, specifically, the blank obtained after primary forging is heated to 1000-1150 DEG C, heat preservation is conducted for 3-6 h, then a middle concave baffle is drawn out to enable the outer diameter of the concave baffle to be the size required by the technology, then the inner diameter of the blank is expanded to the size required by the technology, and a finished product is obtained. The method can avoid the concave center phenomenon and improve the product quality.

Description

Technical Field

[0001] The invention relates to the technical field of forging, and in particular to a forging method of a hollow shaft forging with flanges at both ends. Background Art

[0002] With the progress of the free forging industry, shaft forgings are also developing in the direction of complex shapes and fine forging, such as double flange solid shafts, single flange hollow shafts, double flange hollow shafts, etc. When forging a hollow shaft with a flange on one end, the metal flow direction is single, and the production difficulty is relatively low. The production of hollow shafts with flanges on both ends is the most difficult. The existing forging process steps of hollow shafts with flanges on both ends include removing water risers, upsetting and punching, drawing, dividing materials, drawing again, forging flanges, and producing finished products. The existing process will have the following problems during the forging process: 1. The flange surfaces at both ends are concave, which makes it very easy to have smaller sizes after subsequent processing; 2. After drawing, the inner hole of the blank is locked with the core rod, and the forging cannot be removed; 3. Coarse grains often occur during ultrasonic testing of forgings. Summary of the invention

[0003] In order to solve the above problems, the present invention proposes a forging method for a hollow shaft forging with flanges at both ends, by first forging to form flanges at both ends and then drawing the concave file, using the principle of minimum flow resistance to solve the concave center problem, and using step-type temperature control to solve the coarse grain problem. The specific technical scheme is as follows: A forging method for a hollow shaft forging with flanges at both ends comprises the following steps: S1. Take the steel ingot and pre-treat it: remove the water riser of the steel ingot to obtain a blank.

[0004] S2. Upsetting and punching: Heat the blank to 1150~1250℃, keep it warm for 15~20h, then upset and punch the heated blank.

[0005] S3. Initial hole expansion: Heat the blank after upsetting and punching to 1150~1250℃, keep it warm for 4~8h, and then expand the inner hole of the heated blank.

[0006] S4. Initial drawing: Heat the blank after the initial hole expansion to 1000~1200℃, keep it warm for 4~8h, and then draw the heated blank until the outer diameter of the blank is equal to the outer diameter required by the flange process.

[0007] S5. Forging flanges and recessed blocks: Heat the blank after the initial drawing to 1000~1200℃, keep it warm for 4~8h, draw the middle part of the blank after indentation and separation, and form flanges at both ends and preliminary recessed blocks.

[0008] S6. Drawing-expansion forging: Heat the blank after the initial forging to 1000~1150℃ and keep it warm for 3~6h. Then, draw the preliminary concave section to make the outer diameter of the concave section reach the process requirements. Then, expand the inner diameter of the blank to the process requirements. The concave center of the flange surface is filled and the length of the concave section reaches the process requirements to obtain the finished product.

[0009] Specifically, in S2, the diameter of the blank after upsetting is 1.25 to 2 times its length, and the punching diameter accounts for 30% to 40% of the diameter of the blank after upsetting.

[0010] Specifically, in S3, the inner diameter of the blank after the initial hole expansion is 1.5-2.5 times the punching size.

[0011] Specifically, in S4, the length of the blank after the initial drawing is 1.45-2.5 times the length of the blank after upsetting.

[0012] Specifically, in S5, the single-side step difference between the flange and the preliminary recess is not less than 150 mm.

[0013] Specifically, in S6, the stretching-expansion forging includes the following steps: S6.1. Insert the mandrel into the hole of the blank, and use the upper flat anvil and the lower V-shaped anvil to lengthen the initial concave block so that the outer diameter of the concave block reaches the required size of the process.

[0014] S6.2. Move the working platform of the press to expand the inner diameter of the blank to the size required by the process, fill the concave center of the flange surface, and make the length of the blank reach the size required by the process to obtain the finished product.

[0015] The beneficial effects of the present invention are: 1. Forge the flange first. At this time, the temperature of the blank is high, and the temperature of each part is uniform, the deformation resistance is small, the deformation resistance of the material in each direction is small, and the consistency of each part of the deformation is good; in the drawing-expansion forging, the change in the shape of the blank during the drawing of the middle concave file causes the temperature of the flanges at both ends to drop more significantly, and the deformation resistance is greater. According to the principle of minimum resistance to metal flow, there are constraints at both ends, and the material will not flow to the flanges at both ends. Forging at this time can avoid the concave phenomenon of the concave file part to the greatest extent, which is beneficial to improving product quality. The excess material generated by the expansion of the inner diameter during the expansion of the hole will be filled into the concave center of the flange surface, thereby eliminating the concave center phenomenon of the flange surface.

[0016] 2. In the finished product stage, the combined forging of drawing and expanding is adopted to avoid the problem that the forging is unable to detach after being stuck to the mandrel, which is conducive to improving production efficiency.

[0017] 3. The use of step-by-step temperature control in each forging process can effectively avoid the coarse grain problem of forgings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 It is a schematic diagram of the drawing in the drawing-expansion forging of the present invention; Figure 2 It is a schematic diagram of hole expansion in the stretching-expansion forging described in the present invention.

[0020] In the figure: 1. upper flat anvil; 2. lower V-shaped anvil; 3. blank; 4. mandrel; 5. mandrel support. DETAILED DESCRIPTION

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] Forged flange outer diameter φ 外法 =2300mm, single-side flange length L1=600mm, outer diameter of the concave part between the two end flanges φ 凹 =1600mm, the length of the concave part between the flanges at both ends L2=6100mm, the inner diameter of the hollow shaft φ 内 =1400mm, hollow shaft length L3=7300mm with flanges at both ends as an example, the present invention provides the following specific implementation scheme: The forging method comprises the following steps: S1. Take the steel ingot and pre-treat it: select a 90T steel ingot made of 21CrMo10 material, use a sawing machine to remove the sprue and riser along the sprue and riser line of the steel ingot, and obtain a blank with a size of φ2000mm×3200mm.

[0023] S2, upsetting and punching: the blank obtained in S1 is placed in a gas-fired heating furnace, heated to a temperature of 1150-1250°C, and kept warm for 15-20 hours. In this embodiment, the heating temperature is 1250°C and the holding time is 18 hours. After the blank is taken out of the furnace, it is upset with an upsetting cover plate so that the diameter of the blank after upsetting is 1.25-2 times its length. In this embodiment, the diameter of the blank after upsetting is 2500mm and the length is 2000mm. Then, punching is performed, and the punching diameter accounts for 30%-40% of the diameter of the blank after upsetting. In this embodiment, the punching diameter is 800mm.

[0024] S3. Initial hole expansion: heat the blank after upsetting and punching to 1150-1250°C and keep it warm for 4-8h. In this embodiment, the heating temperature is 1200°C and the holding time is 8h. After the blank is taken out of the furnace, expand the hole so that the inner diameter of the blank after the initial hole expansion is 1.5-2.5 times the punching size. Specifically, in this embodiment, a 750mm diameter horse bar is inserted into the inner hole of the blank, and the inner hole diameter is expanded to 1200mm with a 1500mm upper flat anvil and a horse rack. At this time, the length of the blank is 2100mm and the outer diameter is 2600mm.

[0025] S4, initial drawing: heat the blank after the initial hole expansion to 1000-1200°C, and keep it warm for 4-8h. In this embodiment, the heating temperature is 1150°C and kept warm for 7h. After the blank is taken out of the furnace, draw the heated blank so that the outer diameter of the blank after the initial drawing is equal to the outer diameter required by the flange process, and the length of the blank after the initial drawing is 1.45-2.5 times the length of the blank after upsetting. Specifically, in this embodiment, a mandrel with a diameter of 1200mm is inserted into the inner hole of the blank, and the blank is drawn to a length of 2900mm with a 1500mm upper flat anvil and a 1500mm lower V-shaped anvil. At this time, the outer diameter is 2300mm.

[0026] S5, forging flange and concave block: heat the blank after the initial drawing to 1000-1200°C and keep it warm for 4-8 hours. In this embodiment, the heating temperature is 1100°C and kept warm for 5 hours; form the flanges at both ends and the preliminary concave block through the following steps: S5.1. Insert the mandrel with a diameter of 1200mm into the hole of the blank, and then make indentations and divide the materials according to the flange length.

[0027] S5.2, the mandrel is matched with a 1500mm upper flat anvil and a 1500mm lower V-shaped anvil, and the blank in the middle part after the indentation and material division is pulled out to form a preliminary concave block. At this time, the flange surfaces at both ends will have a concave center phenomenon, and the single-side step difference between the flange and the preliminary concave block, that is, the radius difference is not less than 150mm. In this embodiment, the single-side step difference between the flange and the preliminary concave block is 250mm. At this time, the inner hole of the forging is 1200mm, the outer diameter of the flange is 2300mm, the length of the single-side flange is 600mm, the outer diameter of the preliminary concave block is 1800mm, and the length of the preliminary concave block is 3650mm.

[0028] S6, drawing-expanding forging: the blank after the initial forging is heated to 1000-1150°C and kept warm for 3-6 hours. In this embodiment, the heating temperature is 1050°C and kept warm for 4 hours. After the blank is taken out of the furnace, the drawing-expanding combined forging is performed to obtain the finished product. Figure 1-2 As shown, the drawing-expansion forging includes the following steps: S6.1, if Figure 1 As shown, a 1500mm upper flat anvil 1, a 1200mm diameter mandrel 4, and a 1400mm lower V-shaped anvil 2 are used. The mandrel 4 passes through the blank 3. The upper flat anvil 1 and the lower V-shaped anvil 2 cooperate to stretch and forge the preliminary concave block so that the outer diameter of the concave block reaches the process requirement. At this time, the outer diameter of the concave block is 1600mm and the length of the concave block is 5900mm.

[0029] S6.2, if Figure 2 As shown, the press working platform is moved, and the core rod 4 with the blank is placed on the lower V-shaped anvil 2 and the core rod support 5. The core rod support 5 is used to balance the core rod 4 to make it horizontal. The upper flat anvil 1 expands the entire blank so that the inner diameter of the blank reaches 1400mm. At this time, for the concave part, the inner diameter is enlarged so that its length increases, and the final length of the blank reaches the process requirement size; for the flange part, the inner diameter is enlarged, and the material flows to the concave part of the flange surface to fill the concave center. The final flange outer diameter φ 外法 =2300mm, single-side flange length L1=600mm, outer diameter of the concave part between the two end flanges φ 凹 =1600mm, hollow shaft inner diameter φ 内 =1400mm, the length of the concave part between the flanges at both ends L2=6100mm, the length of the hollow shaft L3=7300mm, and the finished product is obtained.

[0030] During the forging process of this example, the flanges at both ends were relatively flat without any concave centering phenomenon. In addition, during the last forging, the problem of the inner hole locking the core rod and being unable to be removed, which was inevitable in the past, did not occur. The ultrasonic testing results after forging showed clear waveforms without any coarse grain problems.

[0031] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A forging method for a hollow shaft forging with flanges at both ends, characterized in that: The following steps are included: S1, taking a steel ingot and pre-treating the steel ingot: removing the water riser of the steel ingot to obtain a blank; S2. Upsetting and punching: heat the blank to 1150~1250℃, keep it warm for 15~20h, then upset and punch the heated blank; S3, initial hole expansion: heat the blank after upsetting and punching to 1150~1250℃, keep it warm for 4~8h, and then expand the inner hole of the heated blank; S4, initial drawing: heat the blank after the initial hole expansion to 1000~1200℃, keep it warm for 4~8h, and then draw the heated blank until the outer diameter of the blank is equal to the outer diameter required by the flange process; S5. Forging flange and concave block: Heat the blank after the initial drawing to 1000~1200℃, keep it warm for 4~8h, draw the middle of the blank after indentation and division, and form flanges at both ends and preliminary concave block; S6. Drawing-expansion forging: Heat the blank after the initial forging to 1000~1150℃ and keep it warm for 3~6h. Then, draw the initial concave section to make the outer diameter of the concave section reach the process requirement. Then, expand the inner diameter of the blank to the process requirement. The concave center of the flange surface is filled and the length of the blank reaches the process requirement to obtain the finished product.

2. The forging method of a hollow shaft forging with flanges at both ends according to claim 1, characterized in that: In S2, the diameter of the blank after upsetting is 1.25 to 2 times its length, and the punching diameter accounts for 30% to 40% of the diameter of the blank after upsetting.

3. The forging method of a hollow shaft forging with flanges at both ends according to claim 2, characterized in that: In S3, the inner diameter of the blank after the initial hole expansion is 1.5-2.5 times the punching size.

4. The forging method of a hollow shaft forging with flanges at both ends according to claim 3, characterized in that: In S4, the length of the blank after the initial drawing is 1.45-2.5 times the length of the blank after upsetting.

5. The forging method of a hollow shaft forging with flanges at both ends according to claim 1, characterized in that: In S5, the single-side step difference between the flange and the initial recess is not less than 150mm.

6. The forging method of a hollow shaft forging with flanges at both ends according to claim 1, characterized in that: In S6, the drawing-expansion forging includes the following steps: S6.

1. Insert the mandrel into the hole of the blank, and use the upper flat anvil and the lower V-shaped anvil to lengthen the initial concave block so that the outer diameter of the concave block reaches the required size of the process; S6.

2. Move the working platform of the press to expand the inner diameter of the blank to the size required by the process, fill the concave center of the flange surface, make the length of the blank reach the size required by the process, and obtain the finished product.

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