Forging method for improving end bulging of sheet forging stock

Abstract

The invention relates to the technical field of forging, in particular to a forging method for improving bulging of the end of a sheet forging stock. Comprising the following steps that S1, a bar is blanked and heated, and a cubic blank with the end provided with a bulge is formed through upsetting and drawing-out; s2, an upper flat anvil is pressed downwards through a pressing machine to achieve end bulging, flattening and drawing-out are conducted, and an initial forging stock is obtained; s3, a lower flat anvil is replaced with a plane flat anvil, and after the middle forging stock is subjected to third fire heating, the initial forging stock is placed on a large plane flat anvil; the four corners of the initial forging stock are subjected to local flattening deformation, and a middle forging stock is obtained; s4, the middle forging stock is subjected to fourth fire heating, and after heating is completed, the middle forging stock is placed on a plane flat anvil to be integrally flattened; and S5, the intermediate forging stock treated in the step S4 is integrally trimmed to the target size. According to the method, through the strategy that multi-heating-number segmented forming is combined with local preferential deformation, forming of end bulging is remarkably restrained, and the size precision and shape consistency of the forging stock are improved.

Description

Technical Field

[0001] This invention relates to the field of forging technology, specifically to a forging method for improving the bulging of the ends of thin plate forging billets. Background Technology

[0002] Thin-plate parts are a common type of component in structural assembly. These parts typically have right angles at their edges and corners, and their overall shape is close to a regular cube. In the early stages of development, to meet installation requirements and test service performance, free forgings with shorter production cycles are usually chosen to process these parts. When designing free forgings, considering raw material costs and material utilization, the method of the maximum outer contour envelope is used to obtain a simple, regular cube structure based on the part's structure. Since free forgings are obtained using the upper and lower anvils of forging equipment through simple processes (upsetting, drawing, and flattening), the main common production process involves flattening the billet with a full anvil. According to the theory of metal plastic forming and production experience, due to the large contact area between the upper and lower surfaces of the billet and the tooling, the metal has poor vertical flowability. However, the bulging ends of the billet have almost no contact with the tooling. Therefore, based on the law of least resistance in metal deformation, the metal preferentially flows to the bulging ends during full anvil flattening. The final forged billet has problems such as poor dimensional control accuracy, severe local corner collapse, and large bulging at the ends. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a forging method for improving the bulging at the end of thin plate forging blanks, so as to reduce the bulging at the end of the forging blank.

[0004] The technical solution adopted by this invention to solve its technical problem is a forging method for improving the bulging of the end of thin plate forgings, comprising the following steps:

[0005] S1: The bar stock is cut and heated. The heated bar stock is placed between the upper and lower flat anvils for the first forging. Through upsetting and drawing, a cubic billet with bulging ends is formed.

[0006] S2: After the cubic billet is heated for the second time, the cubic billet is placed vertically between the upper and lower flat anvils. The upper flat anvil is pressed down by the press to shrink the end of the cubic billet. Then the cubic billet is placed horizontally between the upper and lower flat anvils to flatten and elongate it to obtain the initial forging billet.

[0007] S3: Replace the lower flat anvil with a flat flat anvil, heat the intermediate forging billet for the third time, and place the initial forging billet on the flat flat anvil; rotate the initial forging billet 30°~45°, and use the press to drive the upper flat anvil to press down to locally flatten and deform the four corners of the initial forging billet, flattening each corner 1~2 times; to obtain the intermediate forging billet.

[0008] S4: Heat the intermediate forging billet for the fourth time. After heating, place the intermediate forging billet on a flat anvil and flatten it as a whole. Control the number of times the press is pressed down in the same position to not exceed 3 times, and the pressing speed is 8~10mm / s.

[0009] S5: The intermediate forging billet processed by S4 is trimmed to the target size to obtain the target forging billet; wherein, the width W of the upper flat anvil satisfies W>D, the length L of the upper flat anvil satisfies L>B / 2sinθ, θ is the initial forging billet rotation angle, D is the bar diameter, and B is the initial forging billet width.

[0010] Furthermore, the upper flat anvil, lower flat anvil, and flat anvil are all preheated to no less than 200°C before use, and the preheating time is no less than 24 hours.

[0011] Furthermore, the heating temperature of the first and second flames is Tβ-(30℃~50℃), the holding time of the first flame is (0.7~1.1)D, where D is the diameter of the bar stock, and the holding time of the second, third and fourth flames is not less than 30 minutes.

[0012] Furthermore, the initial forging blank thickness H satisfies H=H0+(20~30)mm, where H0 is the target forging blank thickness.

[0013] Furthermore, both the upper and lower flat anvils have rounded edges with a radius of 30-50 mm.

[0014] The beneficial effects of this invention are as follows: By combining multi-stage segmented forming with a localized preferential deformation strategy, the formation of end bulges is significantly suppressed, improving the dimensional accuracy and shape consistency of the forging billet; the use of a specific angle of rotational flattening in conjunction with a large-plane anvil guides the metal flow towards the width direction, reducing end excess material and lowering the risk of corner collapse; strict control of press speed, number of presses, and deformation amount avoids overheating and cracking, improving the internal quality and forming stability of the forging billet. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the present invention;

[0016] Figure 2 This is a schematic diagram of the initial forging billet forming an intermediate forging billet;

[0017] Figure 3 This is a schematic diagram of the intermediate forging billet being flattened;

[0018] Figure 4 yes Figure 3 Sectional view along line AA;

[0019] Figure 5 This is a schematic diagram of the intermediate forging billet trimming. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] like Figures 1-5 As shown, the present invention provides a forging method for improving the bulging of the ends of thin plate forgings, comprising the following steps:

[0022] S1: The bar stock is cut and heated. The heated bar stock is placed between the upper and lower flat anvils for the first forging. Through upsetting and drawing, a cubic billet with bulging ends is formed.

[0023] S2: After the cubic billet undergoes a second heating process, it is placed vertically between the upper and lower anvils. A press is used to press down on the upper anvil to flatten the bulge at the ends of the billet. Then, the billet is placed horizontally between the upper and lower anvils for flattening and elongation, obtaining the initial forging billet. The billet is placed vertically, and the upper and lower anvils apply vertical pressure to the end face, directly acting on the most prominent bulge, effectively reducing its height and making the billet end face relatively flat. After the bulge is reduced, the billet is flattened and elongated, controlling the thickness after flattening to H = H0 + (20~30) mm. This reserved 20-30 mm underpressure provides the necessary deformation space for the final overall flattening, ensuring sufficient deformation force to drive metal flow during final forging.

[0024] See Figure 2S3: Replace the lower flat anvil with a flat flat anvil. After the intermediate forging billet undergoes a third heating process, place the initial forging billet on the flat flat anvil. Rotate the initial forging billet 30°~45° and use a press to drive the upper flat anvil downwards to locally flatten and deform the four corners of the initial forging billet, flattening each corner 1~2 times; this yields the intermediate forging billet. Replacing the lower flat anvil with a flat flat anvil provides a larger and flatter support surface, reduces pressure per unit area, facilitates lateral metal expansion, and provides a stable foundation for subsequent operations. Rotating the initial forging billet 30°~45° is key to breaking symmetry and achieving local deformation. After rotation, the upper flat anvil no longer covers the entire width of the billet simultaneously, but instead prioritizes contact with the corner areas of the billet. In traditional full-anvil flattening, the resistance is least in the direction of the bulge at the end, causing metal to rush in and increase the bulge. However, this step, by locally flattening the corners, generates significant deformation resistance in the corner area, forcing the metal in that area to preferentially flow towards the direction of second least resistance, i.e., the center area of ​​the billet's width and length. This is equivalent to pushing excess metal at the corners to areas prone to future material shortages in advance, locking the four corners to prevent flash or material loss during final flattening. The anvil size is limited, i.e., W>B / 2, L>B / 2sinθ: This ensures the upper anvil has sufficient size to efficiently compact the corners of the billet and still cover a sufficient deformation area after rotation, thus completing local deformation with the fewest flattening passes (1-2 times), improving efficiency and preventing excessive temperature drop in the billet.

[0025] See Figure 3 and Figure 4 S4: The intermediate forging billet undergoes a fourth heating process. After heating, the billet is placed on a flat anvil and flattened as a whole. The number of press strokes in the same position is controlled to not exceed 3, and the pressing speed is 8-10 mm / s. After step S3, the four corners of the billet have been compacted, and the metal distribution is more uniform. At this point, the billet is flattened as well. Since the corner areas have become difficult to flow in, the metal is forced to fill all the flowable spaces evenly. The reserved 20-30 mm underpressure is compressed at this moment, and the metal will preferentially flow to the width direction that is not yet fully filled. Only a small amount of metal flows to the ends, forming a very small bulge. Controlling the number of press strokes in the same position to ≤3 is to prevent excessive local temperature rise, which may lead to coarse grains or surface cracks. Controlling the pressing speed to 8-10 mm / s is to ensure the balance between deformation heat and heat dissipation, and to avoid internal overheating.

[0026] See Figure 5 S5: The intermediate forging billet processed by S4 is trimmed to the target size to obtain the target forging billet; wherein, the width W of the upper flat anvil satisfies W>D, the length L of the upper flat anvil satisfies L>B / 2sinθ, θ is the initial forging billet rotation angle, D is the bar diameter, and B is the initial forging billet width.

[0027] To prevent cracking of the forging surface during deformation due to temperature difference between the forging billet and the tooling, the upper flat anvil, lower flat anvil, and flat flat anvil are all preheated to no less than 200°C and the preheating time is no less than 24 hours before use.

[0028] Furthermore, the heating temperature of the first and second flames is Tβ-(30℃~50℃), the holding time of the first flame is (0.7~1.1)D, where D is the diameter of the bar stock, and the holding time of the second, third and fourth flames is not less than 30 minutes.

[0029] Furthermore, the initial forging blank thickness H satisfies H=H0+(20~30)mm, where H0 is the target forging blank thickness.

[0030] Furthermore, both the upper and lower flat anvils have rounded edges with a radius of 30-50 mm. Rounding the edges of the upper and lower flat anvils (R=30-50mm) effectively reduces folding and cracking during the drawing process.

[0031] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A forging method for improving the bulging at the ends of thin plate forgings, characterized in that, Includes the following steps: S1: The bar stock is cut and heated. The heated bar stock is placed between the upper and lower flat anvils for the first forging. Through upsetting and drawing, a cubic billet with bulging ends is formed. S2: After the cubic billet is heated for the second time, the cubic billet is placed vertically between the upper and lower flat anvils. The upper flat anvil is pressed down by the press to shrink the end of the cubic billet. Then the cubic billet is placed horizontally between the upper and lower flat anvils to flatten and elongate it to obtain the initial forging billet. S3: Replace the lower flat anvil with a flat flat anvil, heat the intermediate forging billet for the third time, and place the initial forging billet on the flat flat anvil; rotate the initial forging billet 30°~45°, and use the press to drive the upper flat anvil to press down to locally flatten and deform the four corners of the initial forging billet, flattening each corner 1~2 times; to obtain the intermediate forging billet. S4: Heat the intermediate forging billet for the fourth time. After heating, place the intermediate forging billet on a flat anvil and flatten it as a whole. Control the number of times the press is pressed down in the same position to not exceed 3 times, and the pressing speed is 8~10mm / s. S5: The intermediate forging billet processed by S4 is trimmed to the target size to obtain the target forging billet; wherein, the width W of the upper flat anvil satisfies W>D, the length L of the upper flat anvil satisfies L>B / 2sinθ, θ is the initial forging billet rotation angle, D is the bar diameter, and B is the initial forging billet width.

2. The forging method for improving the bulging at the ends of thin plate forgings according to claim 1, characterized in that, The upper flat anvil, lower flat anvil, and flat anvil are all preheated to no less than 200°C before use, and the preheating time is no less than 24 hours.

3. The forging method for improving the bulging at the ends of thin plate forgings according to claim 1, characterized in that, The heating temperature of the first and second flames is Tβ-(30℃~50℃), the holding time of the first flame is (0.7~1.1)D, where D is the diameter of the bar stock, and the holding time of the second, third and fourth flames is not less than 30 minutes.

4. The forging method for improving the bulging at the ends of thin plate forgings according to claim 1, characterized in that, The initial forging blank thickness H satisfies H=H0+(20~30)mm, where H0 is the target forging blank thickness.

5. A forging method for improving the bulging at the ends of thin-plate forgings according to claim 1, characterized in that, Both the upper and lower flat anvils have rounded edges with a radius of 30-50 mm.

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