CN-122007302-A - Method for eliminating defects in forming process of variable-diameter cylindrical forging

Abstract

The invention relates to the technical field of preparation of reducing cylindrical forgings, in particular to a method for eliminating defects in the process of forming the reducing cylindrical forgings, which comprises the following steps of firstly, preparing a blank, preparing the rest cylindrical metal blank, secondly, preprocessing the blank, putting the blank into a van-type resistance furnace, heating to 930 ℃, and preserving heat for two hours; transferring the blank after discharging from the furnace, placing the blank into a die, performing first-time forging on the die, performing surface pre-forging on the cylindrical metal material, wherein the pre-forging temperature is 920 ℃, cooling for standby, performing second-time forging, heating the blank in the second step to 900 ℃, and performing final forging to complete forging. The invention realizes the technical aims of optimizing the forming process of the reducing cylindrical forging and producing the reducing cylindrical forging with high performance.

Inventors

• LI XIA
• ZHANG LIQIANG
• CAO XIUDONG
• SUN XIAOYANG

Assignees

• 烟台大学
• 烟台市清泉特钢锻造制品有限公司

Dates

Publication Date

20260512

Application Date

20260319

Claims (6)

1. 1. The method for eliminating the defects in the forming process of the reducing cylindrical forging is characterized by comprising the following steps of: Step one, preparing a blank, preparing the balance of cylindrical metal blanks, Step two, pretreating the blank, putting the blank into a van-type resistance furnace, heating to 930 ℃, and preserving heat for two hours; Step three, after discharging, transferring the blank into a die, and forging the die with first firing; performing surface pre-forging on the cylindrical metal material, wherein the pre-forging temperature is 920 ℃, and cooling for standby; and fourthly, performing second fire forging, heating the blank in the second step to 900 ℃, and final forging to complete forging.
2. 2. A method of eliminating defects during a reducing forging forming process according to claim 1, wherein in step one, the billet is a cylindrical titanium alloy billet having a geometric dimension of 293mm in diameter and a height of 146.5mm.
3. 3. The method for eliminating defects in the forming process of a reducing cylindrical forging according to claim 1, wherein in the second step, the pretreatment of the blank is to clean surface defects and to smear 0.2mm lubricant, and the lubricant is water-based glass lubricant.
4. 4. The method for eliminating defects in the forming process of the diameter-variable cylindrical forging according to claim 1, wherein a graphite cushion block is placed at the bottom of a blank during heating, the blank is heated at a heating rate of 2.5 ℃ per minute, the blank is kept at 200 ℃ for 2 hours, then is kept at 600 ℃ for 1 hour, and is kept at 930 ℃ for 2 hours.
5. 5. The method for eliminating defects in the process of forming a variable-diameter cylindrical forging according to claim 1, wherein in the third step, the die comprises an upper die and a lower die which are matched with each other, the upper die is a male die, the lower die is a female die, the minimum width of the female die is adapted to the blank, and a limiting block capable of adjusting the forging stroke of the male die is arranged between the male die and the female die.
6. 6. A method of eliminating defects during a reducing forging forming process according to claim 1, wherein in step three, the stroke of the pre-forging is 80mm.

Description

Method for eliminating defects in forming process of variable-diameter cylindrical forging Technical Field The invention relates to the technical field of preparation of reducing cylindrical forgings, in particular to a method for eliminating defects in the process of forming a reducing cylindrical forgings. Background Early torsion cylinder structural parts in China are mainly manufactured by directly processing titanium alloy or forging a tire mold. Although the processes can realize the basic shape and performance of the component, the shape of the torsion cylinder is formed by transition of multiple sections of circular arcs with different curvatures and straight lines, the inner wall thickness and the outer wall thickness are obviously changed along the axial direction and the radial direction, and the section of the local area is greatly changed. Meanwhile, the aerospace torsion cylinder is usually made of high-strength titanium alloy, has low plasticity and high deformation resistance, and is extremely sensitive to forming process parameters. Thus, the formation of the aerospace torque tube is difficult. The forming process in the prior art adopts a blank with the diameter of 192mm and the height of 109mm, and the forming process can be divided into three stages of an extrusion stage, a boss filling stage and an underfilling stage. The material flow at the extrusion stage presents integral radial extrusion characteristics, the metal at the bottom of the blank has relatively low flow speed due to the restriction of the die, and the whole deformation area presents obvious speed gradient distribution, so that the upper profile of the blank starts to be fitted into the die cavity earlier. With further increase of the reduction, the forming process enters a boss filling stage, at this time, the flow of metal to the central area is enhanced, and the boss part gradually has obvious back extrusion trend. Because of the abrupt shrinkage of the mold geometry, the metal needs to pass through a narrower section to fill the boss area, thus requiring greater resistance to deformation. The metal flow direction around the boss is changed from the original radial flow to axial rising and central converging gradually, but the metal in the boundary area is still influenced by friction to lag the flow, so that the material flow speed around the boss root is relatively low. The differential flow pattern means that the boss is difficult to form, and particularly the transition areas at the upper edge and the two sides of the boss are prone to local underfill. After entering the underfill stage, the metal in the bottom region of the blank begins to be extruded by the upper formed geometry forcing the metal to flow down the lower die cavity and achieve bulk filling. At this stage, the metal mainly flows downwards into the bottom of the die, and the metal flow path is long because the bottom space is relatively closed, so that the metal still has high flow resistance in the bottom forming process. The bottom metal is characterized by high concentrated flow, while the sidewall area is limited by friction and deformation, resulting in a significant drop in flow rate. As the metal gradually fills the bottom of the female die, the cavity finally reaches a saturated state, and the forming process is completed. Disclosure of Invention The invention solves the problem of providing a method for eliminating defects in the forming process of the reducing cylindrical forging, and realizes the technical aims of optimizing the forming process of the reducing cylindrical forging and producing the reducing cylindrical forging with high performance. In order to achieve the above purpose, the present invention adopts the following technical scheme: A method for eliminating defects in the forming process of a reducing cylindrical forging comprises the following steps: Step one, preparing a blank, preparing the balance of cylindrical metal blanks, Step two, pretreating the blank, putting the blank into a van-type resistance furnace, heating to 930 ℃, and preserving heat for two hours; Step three, after discharging, transferring the blank into a die, and forging the die with first firing; performing surface pre-forging on the cylindrical metal material, wherein the pre-forging temperature is 920 ℃, and cooling for standby; and fourthly, performing second fire forging, heating the blank in the second step to 900 ℃, and final forging to complete forging. As an improved technical scheme, in the first step, the blank is a cylindrical titanium alloy blank, and the geometric dimension diameter of the blank is 293mm, and the height of the blank is 146.5mm. As an improved technical scheme, in the second step, the pretreatment of the blank is to clean surface defects and smear 0.2mm lubricant, and the lubricant is water-based glass lubricant. In the second step, a graphite cushion block is placed at the bottom of the blank in a cushioning mode, the temp