Combined forging forming method for square strip type forgings

Abstract

The combined forging forming method comprises the following specific steps that S1, a combined forging ring blank is designed by adjusting the distance between products, and forging and ring rolling forming are conducted on a raw material blank to obtain the combined forging ring blank; and S2, after thermal refining is conducted on the combined forging ring blank, the combined forging ring blank is divided into a plurality of forged pieces according to the design size, and a target product is obtained. Near-net forming of the square strip forgings is achieved, the material utilization rate is increased, the production cycle is shortened, the production cost is reduced, and it is ensured that the material performance reaches the standard and is uniform.

Description

Technical Field

[0001] This invention belongs to the field of metal forming technology, and specifically relates to a method for the combined forging of square bar forgings. Background Technology

[0002] Square bar forgings, as basic structural components, are widely used in core load-bearing parts in fields such as engineering machinery, heavy equipment, and marine propulsion. The traditional manufacturing process for these forgings mainly follows the technical route of "forging bar stock / square billet initial forming → heat treatment → CNC precision machining." The following technical problems exist:

[0003] (1) Low material utilization: Conventional forging usually adopts full envelopment. Taking a typical large square bar forging as an example, the net weight of the final forging is only about 900 kg, but the blank weight is as high as 2722 kg, and the material utilization rate is less than 33%.

[0004] (2) After heat treatment, the amount of rough machining is large, and since the near-net-shape is not achieved in the forging stage, the cooling rate from the surface to the core of the forging is significantly different after heat treatment, which leads to a decrease in the uniformity of the cross-sectional structure. In particular, hardness gradient and residual stress concentration are prone to occur in large-size forgings.

[0005] (3) High production costs, long production cycles, and redundant processing allow for machining time of tens of hours per piece, coupled with high power equipment energy consumption, directly increasing manufacturing costs.

[0006] Therefore, the industry urgently needs to develop a new forming method to achieve near-net-shape forming of such forgings and meet the high-performance requirements of forgings. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a method for the combined forging of square bar forgings. By optimizing the forming scheme and heat treatment method, near-net-shape forming of square bar forgings is achieved, improving material utilization, shortening the production cycle, reducing production costs, and ensuring that material performance meets standards and is uniform.

[0008] The main technical solution adopted in this invention is as follows:

[0009] A method for forging a square bar forging, comprising the following steps:

[0010] S1: By adjusting the product spacing, the forged ring blank is designed, and the raw material blank is forged and rolled into a ring to obtain the forged ring blank;

[0011] S2: After the combined forging ring billet is quenched and tempered, it is divided into multiple forgings according to the design dimensions to obtain the target product.

[0012] Preferably, the specific layout design method for the forged ring billet in S1 is as follows:

[0013] S1-1: Given the inner diameter X1 of the product and the included angle β of the product, let O be the center of the inner diameter of the target product. Draw a circle Q with radius r1 through the center O. Establish a coordinate system with the center O as the origin. Translate the center of the product along the horizontal axis of the coordinate system to point O″ on circle Q.

[0014] S1-2: Rotate the product around the origin O of the coordinate system by an angle of β. Let the outer diameter endpoint of the product before rotation be C and the inner diameter endpoint be C′. Let the outer diameter endpoint of the product after rotation be D and the inner diameter endpoint be D′. Then the distance between the product before and after rotation is the arc length between points C and D.

[0015] S1-3: Extend CC′ and DD′ along their respective product center lines, intersecting at points O″ and O″′ of circle Q. Then, line segment CD = O″O″′, and arc CD ≈ CD = O″O″′ ≈ arc O″O″′; where the formula for calculating arc O″O″′ is:

[0016] Arc O″O″′=2Π×r1×(β / 360) (1);

[0017] Therefore, based on formula (1), the distance r1 that the product moves along the horizontal axis of the coordinate system can be calculated according to the length of arc CD;

[0018] S1-4: After translating the product along the horizontal axis of the coordinate system according to the distance r1 obtained in step 1-3, rotate the product N-1 times with the center O of the coordinate system as the rotation point to obtain the layout scheme of the combined forging ring billet, where N is the number of combined forgings of the target product forgings.

[0019] Preferably, in step S1, if the target product forging includes several square strip-like parts of different sizes, the part spacing is adjusted before adjusting the product forging spacing. The method is as follows: Based on the actual spacing between the parts and according to the equipment capacity, the part spacing is determined to be adjusted to M. Then, taking the center point O′ of the end line segment L of one of the parts as the center, a circle P with radius R0 is drawn, where R0 = M. A line segment L1 parallel to the line segment L and tangent to the circle P is drawn. One end of the line segment L1 is extended so that it intersects the inner diameter circle of the target product at point B. The center of the inner diameter circle of the target product is recorded as O, and the endpoint of the end line segment L near the center O is recorded as A. Then ∠AOB is obtained as α. With the center O as the rotation center, the part is rotated by an angle α, and the part spacing is adjusted to the set value M.

[0020] Preferably, in the combined forging layout scheme, the number N of combined forgings for the target product forgings is calculated as follows:

[0021]

[0022] Where β is the included angle of the target product. This indicates rounding down to the nearest integer.

[0023] Preferably, in step S2, the quenching and tempering process includes sequentially performing quenching and tempering processes.

[0024] Beneficial effects: This invention provides a method for the combined forging of square bar forgings, which has the following advantages:

[0025] (1) This invention introduces the concept of moving distance r1, establishes the relationship between r1 and the arc length of the product spacing, and realizes precise design of the size of the forging ring blank. This significantly reduces the weight of the forging through the forging method and increases the material utilization rate from 33% to 39%. At the same time, multiple target products can be processed on a single ring blank. The final processing only requires milling the inclined surfaces at both ends. The remaining parts can be assembled as required and then removed by machining. This improves production efficiency and shortens the production cycle, which is conducive to reducing manufacturing costs.

[0026] (2) The present invention is formed by forging and rolling rings, which results in a large amount of material deformation, effectively improving the internal quality of the forging and obtaining a metal flow line that is closer to the final shape of the product.

[0027] (3) In this invention, the distance to each surface is basically the same, and the performance is more uniform after heat treatment. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the parts in Example 1;

[0029] Figure 2 This is a schematic diagram of the part spacing adjustment in step 1 of Example 1;

[0030] Figure 3 for Figure 2 A magnified view of part A in the diagram;

[0031] Figure 4 This is a schematic diagram of the part after the adjustment in step 1 of Example 1 is completed;

[0032] Figure 5 This is a schematic diagram of the product in Example 1;

[0033] Figure 6 This is a schematic diagram of the product spacing design for step 2-2 of Example 1;

[0034] Figure 7 for Figure 6 A magnified view of part B in the diagram;

[0035] Figure 8 This is a schematic diagram of the design results in step 2-2 of Example 1;

[0036] Figure 9 for Figure 8 A magnified view of part of C;

[0037] Figure 10 This is a schematic diagram of the layout of the forged ring billet in Example 1;

[0038] Figure 11 Schematic diagram of the forging blank dimensions of the comparative product parts Figure 1 ;

[0039] Figure 12 Schematic diagram of the forging blank dimensions of the comparative product parts Figure 2 . Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application are clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0041] Example 1

[0042] Taking a target product composed of two parts of different sizes as an example, the product is made of alloy steel (38X2H2MΦA) and is formed through a forging process for square bars. The specific steps are as follows:

[0043] Step 1: Perform 1:1 forging design for the target product, such as... Figure 1 The diagram shown is a schematic of the parts in Embodiment 1 (the target product consists of two parts of different sizes). The actual distance between the two parts of the target product is 106.05 mm. Based on the equipment capacity required for cutting the forging and the size of the parts, the distance between the parts needs to be reduced to M = 50 mm. The specific method is as follows:

[0044] like Figure 2-3 As shown, with the center point O′ of the end segment L of one part as the center, draw a circle P with radius R0, where R0 = M = 50mm. Draw a line segment L1 parallel to this line segment and tangent to circle P. Extend one end of line segment L1 so that it intersects the inner diameter circle of the target product at point B. Let the center of the inner diameter circle of the target product be O, and the endpoint of the end segment L closest to the center O be A. Then, ∠AOB is α ≈ 0.91°. Rotate the part by an angle α with the center O as the rotation center, and the spacing between the parts can be adjusted to the set value M = 50mm. Figure 4 As shown;

[0045] Step 2: After adjusting the part spacing, the target products need to be laid out on the ring blank, and the forging dimensions need to be calculated. Therefore, the target product spacing needs to be modified first. The specific method is as follows:

[0046] Step 2-1: In the joint forging layout scheme, the number N of joint forgings for the target product forgings is calculated as follows:

[0047]

[0048] Where β is the included angle of the target product. This indicates rounding down to the nearest integer.

[0049] like Figure 5 As shown, the center distance of the target product from the center O is the radius of the product's nominal inner diameter, which is 3695 mm. The included angle β of the target product is 70.46°. Arranging the product 360° around the center O, we can obtain... Therefore, it can be determined that a maximum of 5 products can be produced from each ring blank.

[0050] Step 2-2: As Figure 6-7 As shown, given the inner diameter X1 of the product and the included angle β of the product, let O be the center of the inner diameter of the target product. Draw a circle Q with radius r1 through the center O. Establish a coordinate system with the center O as the origin. Move the center of the product to the left along the horizontal axis of the coordinate system to point O″ on circle Q.

[0051] Step 2-2: Rotate the product by an angle β around the origin O of the coordinate system (i.e., the center O). Let C be the outer diameter endpoint and C′ be the inner diameter endpoint before rotation. Let D be the outer diameter endpoint and D′ be the inner diameter endpoint after rotation. The distance between the product points is the arc length between points C and D. Since the product is essentially a combination of two circular arcs with the same center, C′ and D′ are approximately parallel. Therefore, numerically, arc CD is approximately equal to line segment CD.

[0052] Steps 2-3: (e.g.) Figure 8 As shown, extending CC′ and DD′ along their respective product centers, intersecting at points O″ and O″′ of circle Q, line segment CD = O″O″′. Since line segment O″O″′ and arc O″O″′ are approximately equal in length, numerically, arc CD ≈ CD = O″O″′ ≈ arc O″O″′. The formula for calculating arc O″O″′ is:

[0053] Arc O″O″′=2Π×r1×(β / 360) (1);

[0054] Therefore, the length of arc CD can be designed according to the equipment capacity, and r1 can be obtained based on formula (1), which is the distance the product moves outward.

[0055] In this embodiment 1, as Figure 9 As shown, β=70.46°. According to the cutting equipment capacity (the cutting equipment capacity is ≥50mm), the arc CD is designed to be 55mm. According to formula (1), r1=45mm can be obtained.

[0056] Steps 2-4: After translating the product to the left along the horizontal axis of the coordinate system according to the distance r1 obtained in Step 2-3, rotate the product four times with the center O of the coordinate system as the rotation point to obtain the layout scheme of the forged ring billet. Then, adjust the allowance according to the maximum outer diameter and minimum inner diameter of the outline in this figure to obtain the size of the forged ring billet, such as... Figure 10 As shown. The adjustment here mainly considers actual production, which involves many complex elements and differs greatly from the theoretical value. Irregular deformation of the workpiece will occur during the actual cutting process, which is unavoidable. Therefore, it is necessary to adjust the theoretical layout dimensions based on on-site experience. This is a routine adjustment, mainly reflected in increasing the outer diameter and decreasing the inner diameter.

[0057] Step 3: Based on the ring billet dimensions obtained in Steps 2-4, the raw material billet is forged and rolled into a ring shape to obtain a ring-shaped billet. The specific method is as follows: After smelting 14T electric furnace ingots using EBT+LF+VD, a 70MN high-speed forging hydraulic press is used to forge the billet into an approximately ring-shaped piece. A SMS 10M ring rolling mill is then used to roll the ring. After machining, the forging quality is confirmed according to the ultrasonic flaw detection standard GOST 24507-80; the forging is dense and defect-free. In this Example 1, the EBT+LF+VD smelting method and the size of the 14T electric furnace ingot are determined based on the alloy material and product size. This invention can be selectively designed by those skilled in the art according to actual needs.

[0058] Step 4: Perform quenching and tempering treatment using a heat treatment chamber gas furnace. The specific method is as follows:

[0059] Step 4-1: Quenching the forged ring billet: The furnace loading temperature is ≤500℃, and the temperature is increased to 850±15℃ according to the power. After homogenization, the temperature is held for 5-7 hours, then water-cooled to room temperature without reheating, in order to ensure complete transformation of the internal structure.

[0060] Step 4-2: Tempering the forged ring billet: Furnace loading temperature ≤350℃, heat to 560-580±10℃ according to power, hold for 14-15 hours after homogenization, and air cool to room temperature.

[0061] Step 4-3: After heat treatment, the forged ring billet is machined to a bright finish to remove the oxide layer on its surface. In this Example 1, the hardness of the billet was measured using a Leeb hardness tester: 366-379 HB, with a difference of 13 HB between the high and low points, proving that the hardness performance of the billet is uniform. In this Example 1, the quenching and tempering process parameters were selectively designed based on the characteristics of the raw materials and the required characteristics of the product.

[0062] Step 5: After heat treatment, the forged ring billet is scribing and cutting according to the design dimensions, dividing it into 5 product groups and one sample block. The removed sample block is used to prepare test specimens according to testing standards, and performance and composition tests are performed. After the product body passes physical and chemical testing, the beveled surfaces at both ends are milled, and after milling, the parts are assembled into a complete ring. The height and inner and outer circles are then machined to obtain the target product.

[0063] In this embodiment 1, the raw material contains the following components in the following weight percentages: C: 0.35-0.40; Si: 0.17-0.37; Mn: 0.5-0.7; P: ≤0.008; S: ≤0.008; Cr: 1.50-1.70; Mo: 0.3-0.4; Ni: 2.4-2.6; V: 0.15-0.25; Al: 0.020-0.045; Cu: ≤0.2; the balance is Fe.

[0064] Comparative Example: Using the same raw material, the target product is formed using the traditional square billet forming and forging method, such as... Figure 11 and 12 The diagram shows the dimensions of the forging blanks for two parts of the target product. The blank height is 160mm.

[0065] Various performance tests were conducted on the target products obtained in Example 1 and the comparative example. The test results are shown in Table 1.

[0066] Table 1. Product performance test results for Example 1 and the comparative example.

[0067]

[0068] As shown in Table 1, the product performance of both Example 1 and the comparative example meets the requirements. Compared with the comparative example, Example 1, while ensuring elongation and shrinkage after fracture, also shows improvements in tensile strength, yield strength, and low-temperature impact performance, with a larger margin for acceptance values ​​for each indicator. Furthermore, its low-temperature impact performance is stable, with minimal fluctuations and good uniformity. This is because the metal flow of the product prepared in Example 1 better conforms to the product shape, and the margin distribution during heat treatment is more uniform, thereby further improving the consistency and overall performance level of the product.

[0069] Meanwhile, Example 1 also has significant advantages in terms of production efficiency: multiple target products can be processed simultaneously on a single ring blank, which greatly improves production efficiency, shortens the production cycle, and helps reduce overall manufacturing costs.

[0070] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for forging and forming a square bar-type forging, characterized in that, The specific steps are as follows: S1: By adjusting the product spacing, the forged ring blank is designed, and the raw material blank is forged and rolled into a ring to obtain the forged ring blank; S2: After the combined forging ring billet is quenched and tempered, it is divided into multiple forgings according to the design dimensions to obtain the target product.

2. The method for forging and forming of square bar forgings according to claim 1, characterized in that, The specific layout design method for the forged ring billet in S1 is as follows: S1-1: Given the inner diameter X1 of the product and the included angle β of the product, let O be the center of the inner diameter of the target product. Draw a circle Q with radius r1 through the center O. Establish a coordinate system with the center O as the origin. Translate the center of the product along the horizontal axis of the coordinate system to point O″ on circle Q. S1-2: Rotate the product around the origin O of the coordinate system by an angle of β. Let the outer diameter endpoint of the product before rotation be C and the inner diameter endpoint be C′. Let the outer diameter endpoint of the product after rotation be D and the inner diameter endpoint be D′. Then the distance between the product before and after rotation is the arc length between points C and D. S1-3: Extend CC′ and DD′ along their respective product center lines, intersecting at points O″ and O″′ of circle Q. Then, line segment CD = O″O″′, and arc CD ≈ CD = O″O″′ ≈ arc O″O″′; where the formula for calculating arc O″O″′ is: Arc O″O″′=2Π×r1×(β / 360) (1); Therefore, based on formula (1), the distance r1 that the product moves along the horizontal axis of the coordinate system can be calculated according to the length of arc CD; S1-4: After translating the product along the horizontal axis of the coordinate system according to the distance r1 obtained in step 1-3, rotate the product N-1 times with the center O of the coordinate system as the rotation point to obtain the layout scheme of the combined forging ring billet, where N is the number of combined forgings of the target product forgings.

3. The method for forging and forming of square bar forgings according to claim 1, characterized in that, In step S1, if the target product forging includes several square strip-shaped parts of different sizes, the part spacing is adjusted before adjusting the product forging spacing. The method is as follows: Based on the actual spacing between the parts and according to the equipment capacity, the part spacing is adjusted to M. Then, taking the center point O′ of the end line segment L of one of the parts as the center, a circle P with radius R0 is drawn, where R0 = M. A line segment L1 parallel to the line segment L and tangent to the circle P is drawn. One end of the line segment L1 is extended so that it intersects the inner diameter circle of the target product at point B. The center of the inner diameter circle of the target product is recorded as O, and the endpoint of the end line segment L near the center O is recorded as A. Then ∠AOB is obtained as α. With the center O as the rotation center, the part is rotated by an angle α, and the part spacing is adjusted to the set value M.

4. The method for forging and forming of square bar forgings according to claim 1, characterized in that, In the combined forging layout scheme, the number N of combined forgings for the target product forgings is calculated as follows: Where β is the included angle of the target product. This indicates rounding down to the nearest integer.

5. The method for forging and forming of square bar forgings according to claim 1, characterized in that, In step S2, the quenching and tempering process includes sequentially performing quenching and tempering processes.

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