Disclosure of Invention
(1) Technical problem to be solved
The embodiment of the invention provides a thermal forming method of a titanium alloy thin-wall small-angle curved surface flanging, which solves the technical problems of cracks, excessive thinning and peroxide ablation at the flanging position of a titanium alloy part with the small-angle curved surface flanging by adopting thermal forming equipment and a step-by-step die forming process.
(2) Technical scheme
The embodiment of the invention provides a thermoforming method of a titanium alloy thin-wall small-angle curved surface flanging, which comprises the following steps:
forming the titanium alloy thin-wall plate into a titanium alloy thin-wall plate with a curved surface flanging by using a flanging die;
and forming the titanium alloy thin-wall plate with the curved surface flanging into the titanium alloy thin-wall plate with the small-angle curved surface flanging by using a bending die.
Further, the method for forming the titanium alloy thin-wall plate into the titanium alloy thin-wall plate with the curved surface flanging by using the flanging die specifically comprises the following steps:
coating protective paint on the surface of the titanium alloy thin-wall plate;
after the temperature of the flanging die is raised to a first set temperature, the titanium alloy thin-wall plate is loaded into the flanging die, and the titanium alloy thin-wall plate is accurately positioned on the flanging die;
preheating the titanium alloy thin-wall plate at a first set time, pressurizing at a set pressure, and taking out the titanium alloy thin-wall plate with the curved surface flanging after pressure maintaining at a second set time.
Further, the bending die is used for forming the titanium alloy thin-wall plate with the curved surface flanging into the titanium alloy thin-wall plate with the small-angle curved surface flanging, and the method specifically comprises the following steps:
after the temperature of the bending die is raised to a second set temperature, the titanium alloy thin-wall plate with the curved surface flanging is filled;
preheating the titanium alloy thin-wall plate with the curved surface flanging at a third set time, and forming at a set pressing speed until a male die and a female die of the bending die are matched;
and maintaining the pressure for a fourth set time, and taking out the titanium alloy thin-wall plate with the small-angle curved surface flanging.
Further, the first set temperature is 700 ℃ to 750 ℃.
Further, the first set time is 1-5 min, and the second set time is 3-5 min.
Further, the set pressure is 20-40 t.
Further, the second set temperature is 700 ℃ to 750 ℃.
Further, the third set time is 8-15 min.
Further, the set pressing speed is 80-120 mm/min.
Further, the fourth set time is 1-3 min.
(3) Advantageous effects
In conclusion, the process method of the invention adopts the hot forming equipment and the step-by-step die forming, so that the tension-compression stress at the bending position of the small-angle curved surface formed in the second step is reduced; the small-angle curved surface is bent and formed, and anti-instability measures are applied to the inner side and the outer side of the position of the curved surface flanging at the bent position, so that the material instability at the position of the curved surface flanging can be inhibited on the basis of further reducing the forming stress at the position of the curved surface flanging, and the smooth surface is ensured.
Detailed Description
The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the invention and are not intended to limit the scope of the invention, i.e., the invention is not limited to the embodiments described, but covers any modifications, alterations, and improvements in the parts, components, and connections without departing from the spirit of the invention.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
Fig. 1 is a schematic flow diagram of a method for thermoforming a titanium alloy thin-wall small-angle curved surface flange according to an embodiment of the present invention, and fig. 2 is a schematic structural change diagram of a titanium alloy thin-wall plate in the method for thermoforming a titanium alloy thin-wall small-angle curved surface flange according to an embodiment of the present invention, as shown in fig. 1-2, the method for thermoforming a titanium alloy thin-wall small-angle curved surface flange according to an embodiment of the present invention includes the following steps:
and S1, forming the titanium alloy thin-wall plate 1 into the titanium alloy thin-wall plate 2 with the curved surface flanging by using the flanging die.
In the step, the rectangular flat plate type titanium alloy thin-wall plate 2 is formed into a shape with a cambered bottom surface and curved surface flanges at two sides, and the curved surface flange allowance is accurately controlled.
And S2, forming the titanium alloy thin-wall plate 2 with the curved surface flanging into the titanium alloy thin-wall plate 3 with the small-angle curved surface flanging by using a bending die.
In this step, under the precondition of applying an anti-destabilization measure to the bending area and reducing the material deformation rate, the smooth curved surface flanging is formed into a curved surface flanging with a small angle (the embodiment of the invention takes a double-Z-shaped curved surface flanging as an example).
As a preferred embodiment, in step S1, the forming of the titanium alloy thin-walled plate into the titanium alloy thin-walled plate with the curved-surface flange by using the flange mold specifically includes the following steps:
s101, coating protective paint on the surface of the titanium alloy thin-wall plate 1;
s102, after the temperature of the flanging die is raised to a first set temperature, the titanium alloy thin-wall plate 1 is loaded, and the titanium alloy thin-wall plate 1 is accurately positioned on the flanging die;
s103, preheating the titanium alloy thin-wall plate 1 at a first set time, pressurizing at a set pressure, maintaining the pressure at a second set time, and taking out the titanium alloy thin-wall plate 2 with the curved surface flanging.
As a preferred embodiment, in step S2, the method for forming a titanium alloy thin-walled sheet with a curved surface flange into a titanium alloy thin-walled sheet with a small-angle curved surface flange by using a bending die specifically includes the following steps:
s201, heating the bending die to a second set temperature, and then loading the heated bending die into a titanium alloy thin-wall plate 2 with a curved surface flanging;
s202, preheating the titanium alloy thin-wall plate 2 with the curved surface flanging at a third set time, and forming at a set pressing speed until a male die and a female die of a bending die are matched;
and S203, keeping the pressure for a fourth set time, and taking out the titanium alloy thin-wall plate 3 with the small-angle curved surface flanging.
In this embodiment, specifically, fig. 3 is a schematic diagram of a process of bending a titanium alloy thin-walled sheet in a length direction in a thermal forming method of a titanium alloy thin-walled small-angle curved flanging according to an embodiment of the present invention, FIG. 4 is a schematic diagram of a bending process in a width direction of a titanium alloy thin-walled sheet material in a thermal forming method of a titanium alloy thin-walled small-angle curved surface flanging provided by an embodiment of the present invention, as shown in fig. 3-4, a first constraint force a and a second constraint force B are respectively applied at the bending positions at the two ends along the length direction of the titanium alloy thin-walled sheet 2 with the curved surface flanging to form small-angle curved surface flanging, and a third constraint force C and a fourth constraint force D are respectively applied at the bending positions at the two ends along the width direction of the titanium alloy thin-walled sheet 2 with the curved surface flanging, so as to finally form the titanium alloy thin-walled sheet 3 with the small-angle curved surface flanging.
In a preferred embodiment, the first set temperature is 700 ℃ to 750 ℃.
In a preferred embodiment, the first set time is 1-5 min, and the second set time is 3-5 min. The first set time is preferably 3 min.
In a preferred embodiment, the set pressure is 20 to 40 t. Preferably 30 t.
In a preferred embodiment, the second set temperature is 700 ℃ to 750 ℃.
In a preferred embodiment, the third set time is 8 to 15 min. Preferably 10 min.
As a preferred embodiment, the pressing speed is set to 80 to 120 mm/min. Preferably 100mm/min, and the method for adjusting the forming parameters of the platform pressing speed reduces the strain rate of the material and is beneficial to reducing the thinning of the outward flanging position.
In a preferred embodiment, the fourth set time is 1 to 3 min. Preferably for 2 min.
The invention is illustrated below by means of specific examples:
examples
1) Blanking of a blank: precisely blanking a titanium alloy sheet blank in the width direction, wherein the width is equal to the width of the molded surface of the part plus the height of the flanging;
2) flanging and forming: after coating protective coating on the surface of a blank, raising the temperature of a flanging die to 700-750 ℃, starting equipment, loading the blank into the blank, accurately positioning the plate on a forming die, preheating for 3min, pressurizing for 30t, and maintaining the pressure for 3-5 min and taking out;
3) bending and forming: starting the equipment after the temperature of the bending die and the blank rises to 700-750 ℃, loading the bent surface flanging blank into the equipment, preheating for 10min, and adjusting the pressing speed of the platform: forming at a speed of 100mm/min until the male die and the female die are matched;
4) maintaining the pressure for 2min, lifting the upper platform, taking out the part and finishing the forming.
Compared with the prior art, the thermal forming method of the titanium alloy thin-wall small-angle curved surface flanging provided by the embodiment of the invention has the following advantages:
for the curved surface flanging part with the angle, firstly, the curved surface flanging is formed, which is beneficial to improving the profile rigidity of the position, and the wrinkling of the inward flanging position and the excessive thinning of the outward flanging position can be prevented in the subsequent bending forming;
in the curved surface flanging forming (the first step forming), the curved surface flanging size of a formed blank is effectively controlled through a manufacturing process of accurately forming a flanging profile, and the tension-compression stress of a Z-shaped bending position formed in the second step is reduced;
the Z-shaped profile is bent and formed (second step of forming), and anti-instability measures are applied to the inner side and the outer side of the position of the curved surface flanging at the bent position, so that the material instability at the position of the curved surface flanging can be inhibited on the basis of further reducing the forming stress at the curved surface flanging, and the smooth profile is ensured;
by adjusting the forming parameters of the platform pressing speed, the strain rate of the material is reduced, and the reduction of the outward flanging position is facilitated.
It should be clear that the embodiments in this specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the drawings. Also, a detailed description of known process techniques is omitted herein for the sake of brevity.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and alterations to this application will become apparent to those skilled in the art without departing from the scope of this invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.