Extension forming method for large-inner-hole narrow-edge characteristic forge piece

Abstract

The invention relates to the technical field of die forging forming, in particular to an extension forming method for a large-inner-hole narrow-edge characteristic forge piece. Comprising the following steps that S1, an upper die and a lower die are oppositely arranged; s2, the blank is placed between an upper die and a lower die after being heated thoroughly, and a hydraulic machine is started for first-time pressing; s3, a forming device is mounted on the lower surface of the upper die and comprises a mounting plate, the mounting plate is detachably connected with the lower surface of the upper die, and a punch is arranged on the lower surface of the mounting plate; s4, the blank pressed in the S2 is put above a lower die after being molten down and heated thoroughly, and a hydraulic machine is started for pressing; s5, the forming device is detached from the lower surface of the upper die, and then the hydraulic machine is started for pressing; according to the method, the multi-heating-number incremental forming and local extension process is carried out on the blank through the forming tool, the material consumption of the skin connecting part is greatly reduced, material waste caused by traditional multiple times of cutting is avoided, the material utilization rate can be increased by 20% or above, and the method is particularly suitable for production of forgings made of expensive materials such as titanium alloy.

Description

Technical Field

[0001] This invention relates to the field of die forging technology, specifically to a method for extending and forming forgings with large inner holes and narrow sides. Background Technology

[0002] In modern manufacturing, forgings, as important mechanical parts blanks, are widely used in aerospace, automotive, shipbuilding, and many other fields. The production process of forgings with connecting skins has always faced numerous challenges. Traditional forging processes often involve multiple cuts of the connecting skin to obtain forgings that meet dimensional and shape requirements. Under traditional processes, excess connecting skin is formed during forging, and this skin needs to be removed through a specialized cutting process to ensure the forging meets subsequent processing or usage standards. For large or extra-large forgings, the forging force of the equipment often necessitates multiple cutting operations to reduce the load, which undoubtedly increases the complexity and cost of the production process. Figure 1 The large-diameter, narrow-edge forging shown has an inner diameter of 500-1000 mm. Due to its complex shape and large projected area, the traditional process often requires 3-6 consecutive cutting operations in its production. From a material utilization perspective, this multiple cutting process results in significant material waste. Each cut renders some usable material scrap, leading to low material utilization. For example, in the aerospace industry, titanium alloy forgings have high raw material costs, and multiple cutting operations can result in a material waste rate of 20%-30%, increasing production costs and causing unnecessary resource consumption. Furthermore, frequent cutting processes also affect production efficiency. The cumulative effect of multiple cutting operations lengthens the entire production cycle. For large-scale production, this severely restricts efficiency improvements and makes it difficult to meet market demands for rapid product delivery.

[0003] In summary, the traditional method of multiple-cutting of the continuous skin in the production process of die forgings with large inner holes and narrow edges has many drawbacks, such as complex production processes, serious material waste, low production efficiency, and impact on product quality stability. There is an urgent need for a new method to optimize the production process and improve production efficiency and material utilization. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for extending and forming a forging with a large inner hole and narrow edge, thereby reducing the amount of the skin portion and improving the material utilization rate.

[0005] The technical solution adopted by this invention to solve its technical problem is a method for forming a forging with a large inner hole and narrow side feature, comprising the following steps:

[0006] S1: The upper and lower dies are arranged opposite each other. The lower surface of the upper die is provided with a first annular groove, and a first boss is provided between the first annular grooves. The upper surface of the lower die is provided with a second annular groove, and a second boss is provided between the second annular grooves. The first and second annular grooves are used to form the edge of the forging, and the first and second bosses are used to form the inner hole of the forging.

[0007] S2: After the billet is thoroughly heated, it is placed between the upper and lower molds. The hydraulic press is started to perform the first pressing, and the pressing force reaches the maximum load of the hydraulic press.

[0008] S3: A forming device is installed on the lower surface of the upper mold. The forming device includes a mounting plate, which is detachably connected to the lower surface of the upper mold. A punch is provided on the lower surface of the mounting plate. The punch is opposite to the second boss, and the projection of the punch on the horizontal plane is located within the projection of the second boss on the water surface.

[0009] S4: After the billet pressed by S2 is thoroughly heated in the furnace, it is placed above the lower mold, and the hydraulic press is started to press it.

[0010] S5: Remove the forming device from the lower surface of the upper mold, and place the billet that has been pressed by S4 back into the furnace for heat treatment and then place it above the lower mold. Then start the hydraulic press for pressing.

[0011] S6: After removing the connecting skin between the edges of the billet pressed by S5, the target forging is formed.

[0012] Furthermore, the upper and lower surfaces of the punch are transitioned by an inclined surface.

[0013] Furthermore, the cross-section of the punch is circular, rectangular, or equilateral trapezoidal.

[0014] The beneficial effects of this invention are: by using forming fixtures to perform multi-stage progressive forming and local extension processes on the billet, the amount of material used in the connected skin part is greatly reduced, avoiding the material waste caused by traditional multiple cutting, and the material utilization rate can be increased by more than 20%, which is especially suitable for the production of forgings of expensive materials such as titanium alloys. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the forging of the present invention;

[0016] Figure 2 This is a schematic diagram of the molding device installed on the upper mold;

[0017] Figure 3 This is a schematic diagram of the lower mold;

[0018] Figure 4 This is a schematic diagram showing the forging process of the traditional method and the forging of the present invention with the skin still attached.

[0019] Reference numerals: 1-Upper mold; 101-First annular groove; 102-First boss; 2-Lower mold; 201-Second annular groove; 202-Second boss; 3-Mounting plate; 4-Punch; 5-Fasting bolt. 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 1-3 As shown, the present invention provides a method for forming a forging with a large inner hole and narrow side, comprising the following steps:

[0022] S1: The upper mold 1 and the lower mold 2 are arranged opposite to each other. The lower surface of the upper mold 1 is provided with a first annular groove 101, and a first boss 102 is provided between the first annular grooves 101. The upper surface of the lower mold 2 is provided with a second annular groove 201, and a second boss 202 is provided between the second annular grooves 201. The first annular groove 101 and the second annular groove 201 are used to form the edge of the forging, and the first boss 102 and the second boss 202 are used to form the inner hole of the forging. The lower surface of the upper mold 1 is machined with the first annular groove 101 and the first boss 102. The first annular groove 101 is used to form the edge of the forging, and the first boss 102 corresponds to the inner hole area of ​​the forging. The lower mold 2 corresponds to the upper mold 1, and its upper surface is provided with the second annular groove 201 and the second boss 202. The second boss 202 and the first boss 102 together constitute the space for forming the inner hole, and their horizontal projections should completely overlap to ensure the dimensional accuracy of the inner hole.

[0023] S2: After the billet is heated through, it is placed between the upper mold 1 and the lower mold 2. The hydraulic press is started to perform the first pressing, and the pressing force reaches the maximum load of the hydraulic press. The purpose of this step is to fill the cavity with metal and initially form the overall outline of the forging, including the skin structure of the edge and the inner hole.

[0024] S3: A forming device is installed on the lower surface of the upper mold 1. The forming device includes a mounting plate 3, which is detachably connected to the lower surface of the upper mold 1. A punch 4 is provided on the lower surface of the mounting plate 3. The punch 4 is opposite to the second boss 202, and the projection of the punch 4 on the horizontal plane is within the projection of the second boss 202 on the water surface. The forming device includes the mounting plate 3 and the punch 4 fixed to its lower surface. The mounting plate 3 is detachably connected to the upper mold 1 by fastening bolts 5, which facilitates flexible installation and removal at different process stages. To better achieve the installation of the mounting plate 3, a positioning groove can be designed on the lower surface of the upper mold 1 to achieve the positioning of the mounting plate 3. The projection of the punch 4 on the horizontal plane should be completely within the projection range of the second boss 202, so as to achieve local extension of the inner hole connecting skin area in subsequent hot pressing, gradually reduce the connecting skin thickness, and avoid excessive load in one forming.

[0025] S4: After the billet pressed by S2 is reheated in the furnace, it is placed above the lower die 2 and the hydraulic press is started to press it. During this process, the punch 4 applies local pressure to the inner hole skin area, causing the metal in this part to extend to the edge, gradually reducing the skin thickness, while avoiding the distortion of the edge shape.

[0026] S5: Remove the forming device from the lower surface of the upper mold 1, and place the billet after pressing in S4 back into the furnace for heat treatment on the lower mold 2. Then start the hydraulic press for pressing. Since the metal in the skin part extends to the edge after pressing in step S4, the purpose of this pressing is to continue to extend the metal in the skin part to the edge, further reducing the thickness of the skin part.

[0027] S6: After removing the connecting skin between the edges of the billet pressed by S5, the target forging is formed. Since the thickness of the connecting skin has been significantly reduced by the multiple heating processes of the punch, the time required to remove the connecting skin and the material loss are greatly reduced, and the target forging that meets the design requirements is finally obtained.

[0028] To facilitate demolding and to better extend the metal of the connected parts towards the edge, the upper and lower surfaces of the punch 4 are further connected by an inclined surface, and the outer dimensions of the upper surface are larger than those of the lower surface.

[0029] Furthermore, the cross-section of the punch 4 is circular, rectangular, or equilateral trapezoidal. To improve applicability, when the inner hole of the forging is circular, the cross-section of the punch 4 is circular; when the inner hole of the forging is rectangular, the cross-section of the punch 4 is rectangular; and when the edge of the inner hole is arc-shaped, the cross-section of the punch 4 can be equilateral trapezoidal.

[0030] Example 1

[0031] S1: The upper die 1 and the lower die 2 are respectively machined to form a first annular groove 101 and a second annular groove 201, wherein the width of the first annular groove 101 and the second annular groove 201 is consistent with the edge of the target forging. After the molds are closed, the first boss 102 and the second boss 202 are in contact. The punch 4 of the forming device is made of H13 mold steel, and its lower surface is circular with a diameter smaller than that of the second boss 202, ensuring that the projection is completely within the scope of the boss.

[0032] S2: Select standard TC4-DT titanium alloy round billets, preheat them in a heating furnace to 950℃~980℃, and keep them warm for 1.2 minutes per millimeter of billet diameter to ensure thorough heating.

[0033] S3: Place the heated blank into the second cavity of the lower mold 2, and the upper mold 1 moves downward to press it. The pressing force reaches the maximum load of the hydraulic press of 80,000 tons. After holding the pressure for 5 to 40 seconds, the upper mold 1 is lifted.

[0034] S4: Secure the forming device to the lower surface of the upper die 1 using fastening bolts 5, ensuring that the punch 4 and the second boss 202 are aligned. Reheat the blank after the first pressing to the same temperature in the furnace, place it on the lower die 2, and perform a second pressing. The pressing force for this second pressing is 30% to 70% of the maximum load.

[0035] S5: Remove the forming device, return the billet to the furnace for heating, and perform the third and fourth pressing. Each pressing is carried out with a pressing force of 80,000 tons at full capacity, and the holding time is gradually extended.

[0036] S6: After the formed forging is cooled, the connecting skin between the edges is removed by wire cutting or milling to obtain the complete target forging.

[0037] See Figure 4 The diagram shows the final shape of the forging after extrusion and expansion. The skin in the central area has been extruded to 10-30mm, while the traditional method has a skin thickness of 80-100mm, thus reducing the thickness of the skin portion.

[0038] 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 method for forming a forging with a large inner hole and narrow side features, characterized in that, Includes the following steps: S1: The upper mold (1) and the lower mold (2) are arranged opposite to each other. The lower surface of the upper mold (1) is provided with a first annular groove (101) and a first boss (102) is provided between the first annular grooves (101). The upper surface of the lower mold (2) is provided with a second annular groove (201) and a second boss (202) is provided between the second annular grooves (201). The first annular groove (101) and the second annular groove (201) are used to form the edge of the forging, and the first boss (102) and the second boss (202) are used to form the inner hole of the forging. S2: After the billet is heated through, it is placed between the upper mold (1) and the lower mold (2), and the hydraulic press is started for the first pressing. The pressing force reaches the maximum load of the hydraulic press. S3: A forming device is installed on the lower surface of the upper mold (1). The forming device includes a mounting plate (3). The mounting plate (3) is detachably connected to the lower surface of the upper mold (1). A punch (4) is provided on the lower surface of the mounting plate (3). The punch (4) is opposite to the second boss (202), and the projection of the punch (4) on the horizontal plane is located within the projection of the second boss (202) on the water surface. S4: After the billet pressed by S2 is heated through in the furnace, it is placed above the lower mold (2), and the hydraulic press is started to press it; S5: Remove the forming device from the lower surface of the upper mold (1), place the blank after it has been pressed by S4 back into the furnace for heat treatment, and then start the hydraulic press for pressing; S6: After removing the connecting skin between the edges of the billet pressed by S5, the target forging is formed.

2. The method for forming a forging with a large inner hole and narrow side as described in claim 1, characterized in that: The upper and lower surfaces of the punch (4) are transitioned by an inclined surface, and the outer dimensions of the upper surface are larger than those of the lower surface.

3. The method for forming a forging with a large inner hole and narrow side as described in claim 1, characterized in that: The cross-section of the punch (4) is circular, rectangular or equilateral trapezoidal.

Images