An isothermal forging die and forging method for titanium alloy blades

Abstract

An isothermal forging die for titanium alloy blades includes a pre-forging die and a forming die. The connection between the tenon pre-forging cavity of the pre-forging die and the blade body pre-forging cavity is achieved through a curved surface, as is the connection between the guide vane pre-forging cavity and the blade body pre-forging cavity. The forming die has outward-facing flow guide channels on both sides of the blade body forming cavity. This invention designs the pre-forging die based on the shape of the intermediate billet. The pre-forging die features multiple blunting and rounded surface transitions instead of chamfers, allowing for uniform deformation of the intermediate billet during forging and effectively reducing forging defects such as missing material and folding. The upper and lower dies of the forming die each have pre-reserved flow guide channels of a certain width, transforming a closed die into a pseudo-open die. This allows for better control of the forging dimensions and forming process. During forging, the coating material can first enter the flow guide channels, enabling the titanium alloy to fill the two curved edges of the blade body forming cavity.

Description

Technical Field

[0001] This invention relates to the field of machinery, and more particularly to isothermal forging technology for complex irregular-shaped parts, especially an isothermal forging die and forging method for titanium alloy blades. Background Technology

[0002] As aircraft engines develop towards lightweight, high-performance, and low-cost designs, engine blades, as key engine components, are crucial for improving engine performance through their design, production, and performance assurance. Titanium alloys, with their high specific strength, high temperature resistance, and corrosion resistance, and the ability to be superplasticized to near-net-shape at certain temperatures, meet the development goals of lightweight, high-performance, and cost-reduced aircraft engines. Currently, titanium alloy blades are widely used in the engine field. Currently, in the research on titanium alloy blade forming, patent document CN201310431900.7 discloses a method for preparing titanium alloy blades by investment casting, and spraying WC-based cermet onto the blades to improve their surface properties; patent document CN201310536829.9 discloses a method for preparing aluminum-titanium alloy blades by casting aluminum-titanium alloy blades, followed by three heat treatments, and then spraying cermet; patent document CN201210336330.9 discloses a forging process for titanium alloy blades, providing a forging process that includes forging temperature, forging speed, and holding time; patent document CN201310660716.X discloses a forging method for titanium alloy blades, which designs matching forging blanks, molds, and final forging dies according to the blade twist angle. The production process includes firstly, free hammer forging of heated billets in the mold to form a blank forging, and the blank forging is carried out in three stages. Then the forging blank is heated and then placed into the final forging die for hammer forging of the forging blank; CN201410624056.4 discloses a forging forming method for titanium alloy blades, which uses two symmetrical left and right half extrusion dies in conjunction with extrusion die sleeves to forge blades. During the forging process, the position of the extrusion die sleeves needs to be moved and the tightness of the die sleeves adjusted so that the left and right half dies can move horizontally so that the press punch can continue to fall and the subsequent titanium alloy can flow smoothly.

[0003] This shows that while much research has been conducted on titanium alloy blade forging in existing technologies, problems remain, including complex production processes, difficulties in forging, and a large workload in post-forming machining. For engine blades, there is still a lack of designs and forging methods that facilitate blade forming and efficient mass production of blade forgings. Taking the forging process of TC6 titanium alloy blades as an example, the TC6 titanium alloy blade has a complex curved surface, multiple blade twists, large deformation of the guide vanes, and tilted tenons. These problems include: 1. The formed forgings are prone to missing material and folding. 2. During forging, a lubricating coating is applied to the intermediate billet. Due to the thinness and small angle of the curved edges on both sides of the blade body, the lubricating coating first enters the curved edges of the cavity and then accumulates inside, hindering the flow of titanium alloy and making it difficult for the titanium alloy to fill the curved edges. Summary of the Invention

[0004] The purpose of this invention is to provide an isothermal forging die and forging method for titanium alloy blades. This isothermal forging die and forging method for titanium alloy blades aims to solve the technical problems in the prior art, such as the easy occurrence of missing material, folding phenomenon, and difficulty in filling the arc edge of titanium alloy.

[0005] The present invention discloses an isothermal forging die for titanium alloy blades, comprising a pre-forging die and a forming die. The cavity of the pre-forging die includes a blade body pre-forging cavity, a tenon pre-forging cavity, and a guide vane pre-forging cavity. The tenon pre-forging cavity is located at the end of the blade body cavity, and the connection between the tenon pre-forging cavity and the blade body pre-forging cavity is achieved through a curved surface. The guide vane pre-forging cavity is located in the middle of the blade body pre-forging cavity, and the connection between the guide vane pre-forging cavity and the blade body pre-forging cavity is achieved through a curved surface. The cavity of the forming die includes a blade body forming cavity, a guide vane forming cavity, and a tenon forming cavity. The guide vane forming cavity is located on the upper and lower sides of the blade body forming cavity. Each of the two arc-shaped edges of the blade body forming cavity has a flow guiding channel extending outward from one end of the blade body forming cavity to the other end.

[0006] Furthermore, both the pre-forging die and the forming die are closed dies.

[0007] Furthermore, the width of the flow guiding channel is 10 mm.

[0008] The present invention also provides a method for forging titanium alloy blades using the isothermal forging die, comprising the following steps:

[0009] 1. Pre-forging: The blank round bar coated with lubricating coating is placed into the pre-forging die and forged to obtain the intermediate billet. The forging temperature is 0~50℃ below the phase transformation point of titanium alloy, the forging pressure is 1000T, and the initial forging speed is less than or equal to 10mm / s.

[0010] 2. Forming and forging: After applying a lubricating coating to the intermediate billet, it is placed in the forming mold. The forging temperature is controlled at 0~50℃ below the phase transformation point of the titanium alloy, the forging pressure is below 1000T, and the forging speed is 0~2mm / s. The titanium alloy is then pressed down to gradually fill the cavity of the forming mold and the flow guide channel to obtain the formed forging.

[0011] 3. Ejection: The formed forging is ejected using an integral ejection method;

[0012] 4. Heat treatment: Remove the false flash formed by the flow guide channel before heat treatment, and anneal the formed forging twice.

[0013] Compared with existing technologies, the advantages of this invention are positive and significant. This invention designs a pre-forging die based on the shape of the intermediate billet. The pre-forging die features multiple blunting and rounded transitions instead of chamfers, allowing for uniform deformation of the intermediate billet during forging. This ensures the titanium alloy fills the cavity of the forming die, guaranteeing uniform forging performance and effectively reducing forging defects such as folding and missing material. The forming die extends 10mm outward along both sides of the blade rim to form a false flash channel. This means that a certain width of flow guide channel is designed in both the upper and lower dies of the forming die, transforming a closed die into a pseudo-open die. This allows for better control of forging dimensions and the forming process. During forging, the coating material can first enter the flow guide channel, leaving space for smoother titanium alloy flow. This allows the titanium alloy to fill the arc-shaped edges on both sides of the blade body forming cavity, ensuring complete filling of the forming die cavity and obtaining a well-formed forging with reduced folding and missing material. Furthermore, by controlling the deformation rate and temperature in the forging method of this invention, forging products with stable and excellent performance can be obtained. Attached Figure Description

[0014] Figure 1 A schematic diagram of an intermediate billet forged using the pre-forging die of this invention.

[0015] Figure 2 A schematic diagram of a forged part produced using the forming mold of this invention.

[0016] Figure 3 This is a cross-sectional view of the blade body cavity of the molding die in this invention.

[0017] Figure 4 This is a cross-sectional view of the guide vane cavity of the molding die in this invention. Detailed Implementation

[0018] The present invention will be further described below with reference to embodiments, but the present invention is not limited to these embodiments. Any similar structures and similar variations of the present invention should be included within the scope of protection of the present invention. The use of directions such as up, down, front, back, left, and right in the present invention is only for the convenience of clear description and is not intended to limit the technical solution of the present invention.

[0019] like Figures 1-4 As shown, an isothermal forging die for a titanium alloy blade according to the present invention includes a pre-forging die and a forming die; the cavity of the pre-forging die includes a blade body pre-forging cavity, a tenon pre-forging cavity, and a guide vane pre-forging cavity, the tenon pre-forging cavity being located at the end of the blade body cavity, and the connection between the tenon pre-forging cavity and the blade body pre-forging cavity is through a curved surface (corresponding to...). Figure 1 The first curved surface 7 of the intermediate billet is connected, and the guide vane pre-forging cavity is located in the middle of the blade body pre-forging cavity. The connection between the guide vane pre-forging cavity and the blade body pre-forging cavity is through a curved surface (corresponding to...). Figure 1 The second curved surface 8 of the intermediate blank is connected; the cavity of the forming mold includes the blade body forming cavity 5, the guide vane forming cavity 6 and the tenon forming cavity. The guide vane forming cavity 6 is located on the upper and lower sides of the blade body forming cavity 5. Each of the two arc-shaped edges of the blade body forming cavity 5 is provided with a flow guide channel 3 extending outward. Both flow guide channels 3 extend from one end of the blade body forming cavity 5 to the other end.

[0020] Furthermore, both the pre-forging die and the forming die are closed dies. The closed die design allows for a more uniform distribution of the original billet.

[0021] Furthermore, the width of the flow guide channel 3 is 10 mm.

[0022] The present invention also provides a method for forging titanium alloy blades using the isothermal forging die, comprising the following steps:

[0023] 1. Pre-forging: The blank round bar coated with lubricating paint is placed in the pre-forging die and forged to obtain an intermediate billet. The forging temperature is 0~50℃ below the phase transformation point of titanium alloy, the forging pressure is 1000T, and the initial forging speed is less than or equal to 10mm / s. This ensures better forming of parts with large deformation, such as tenon 11 and guide vane 12. The resulting intermediate billet is as follows: Figure 1 As shown;

[0024] 2. Forming Forging: After applying a lubricating coating to the intermediate billet, it is placed in a forming mold. The forging temperature is controlled at 0~50℃ below the phase transformation point of the titanium alloy, and the forging pressure is below 1000T. The forging is slowly pressed down at a forging rate of 0~2mm / s, allowing the titanium alloy to gradually fill the cavity of the forming mold and the flow guide channel 3, thus obtaining the formed forging, such as... Figure 2 As shown;

[0025] 3. Ejection: The formed forging is ejected as a whole to avoid blade warping and deformation;

[0026] 4. Heat treatment: Remove the false flash formed by the flow guide channel 3 before heat treatment, and anneal the formed forging twice.

[0027] Specifically, the blade includes the blade body 10, tenon 11, guide vane 12, etc. The forming mold is as follows: Figure 3 , Figure 4 As shown, it includes an upper mold 1, a lower mold 2, and a flow guide channel 3 (false flash channel). Figure 3 The blank section 4 in the blank corresponds to the section of the blade body 10. Figure 4 The cross-section of the billet 4 corresponds to the cross-section of the guide vane 12. During installation, the lower die 2 is fixedly connected to the lower base, and the upper die 1 is fixedly connected to the upper base. During forging, the billet 4 flows along the gap between the dies and gradually fills the cavity. In the later stage of forging, when the titanium alloy flows to the flow guide channel 3, it continues to fill the arc-shaped edges on both sides of the blade body under pressure, thus obtaining the target forging.

[0028] Specifically, the closed mold, lubricating coating, integral ejection method, annealing method, etc. in this embodiment all adopt well-known solutions in the prior art, which are already known to those skilled in the art, and will not be described in detail here.

[0029] The working principle of this embodiment:

[0030] This invention is applicable to complex irregular-shaped parts, such as arc-edged forgings like aircraft engine blades.

[0031] The pre-forging die is designed based on the shape of the intermediate billet. The pre-forging die has many sharp edges and blunt edges, and uses smooth curved surfaces to replace chamfers. This allows the intermediate billet to deform evenly when the forming die is forging, so that the titanium alloy fills the cavity of the forming die. This ensures the uniformity of the forging performance and effectively reduces the phenomenon of missing material and folding in the forging.

[0032] Based on the dimensional parameters of the forging and the intermediate billet, a forming mold is designed. The forming mold is expanded 10mm outward along the rim of both sides of the blade to form a false flash channel. That is, a certain width of flow guide channel 3 is designed and reserved in the upper and lower molds of the forming mold, so that the closed mold becomes a false open mold. This allows for better control of the forging size and forming process. During forging, the coating can first enter the flow guide channel 3, thus leaving space for the titanium alloy to flow more smoothly. This allows the titanium alloy to fill the arc-shaped edges on both sides of the forming cavity 5 of the blade body, thereby ensuring that the titanium alloy fills the cavity of the forming mold, obtaining a well-formed forging, and reducing folding and missing material phenomena.

[0033] This invention only requires two sets of tooling dies, a pre-forging die and a forming die, to forge the target blade. This is beneficial for forging blades with complex shapes, reducing the amount of post-forging machining, reducing machining allowance, lowering manufacturing costs, improving material utilization, and shortening the forging time. It also enables mass production and improves the success rate and production efficiency of blade forging.

[0034] By controlling the deformation rate and temperature in the forging method of this invention, forging products with stable and excellent performance can be obtained.

Claims

1. A method for forging titanium alloy blades using isothermal forging dies, characterized in that: The isothermal forging die includes a pre-forging die and a forming die. The cavity of the pre-forging die includes a blade body pre-forging cavity, a tenon pre-forging cavity, and a guide vane pre-forging cavity. The tenon pre-forging cavity is located at the end of the blade body cavity, and the connection between the tenon pre-forging cavity and the blade body pre-forging cavity is through a curved surface. The guide vane pre-forging cavity is located in the middle of the blade body pre-forging cavity, and the connection between the guide vane pre-forging cavity and the blade body pre-forging cavity is through a curved surface. The cavity of the forming die includes a blade body forming cavity, a guide vane forming cavity, and a tenon forming cavity. The guide vane forming cavity is located on the upper and lower sides of the blade body forming cavity. Each of the two arc-shaped edges of the blade body forming cavity has a flow guide channel extending outward from one end of the blade body forming cavity to the other end. The method for forging titanium alloy blades includes the following steps: (1) Pre-forging: The blank round bar coated with lubricating coating is placed into the pre-forging mold and forged to obtain the intermediate billet. The forging temperature is 0~50℃ below the phase transformation point of titanium alloy, the forging pressure is 1000T, and the initial forging speed is less than or equal to 10mm / s. (2) Forming forging: After applying lubricating coating to the intermediate billet, it is placed in the forming mold. The forging temperature is controlled at 0~50℃ below the phase transformation point of the titanium alloy, the forging pressure is below 1000T, and the forging rate is 0~2mm / s. The titanium alloy is gradually filled into the cavity of the forming mold and the flow guide channel to obtain the formed forging. (3) Ejection: The formed forging is ejected by integral ejection; (4) Heat treatment: Remove the false flash formed by the flow guide channel before heat treatment, and anneal the formed forging twice.

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