CN115592025A

CN115592025A - Thermal expansion forming die and forming method for titanium alloy thin-wall barrel part with angular rotation center line

Info

Publication number: CN115592025A
Application number: CN202211336948.5A
Authority: CN
Inventors: 王绪坚; 张林嘉; 李英; 张蕾; 戴兴敏; 杜奎; 李兵兵; 曹俊
Original assignee: AECC Guizhou Liyang Aviation Power Co Ltd
Current assignee: AECC Guizhou Liyang Aviation Power Co Ltd
Priority date: 2022-10-28
Filing date: 2022-10-28
Publication date: 2023-01-13

Abstract

The invention discloses a thermal expansion forming die and a forming method for a titanium alloy thin-wall cylinder part with an angle of a rotation center line. A titanium alloy plate is used as a blank, and a plurality of identical hot-stretched parts are processed by hot-stretch forming; cutting the same cut parts on each hot stretching part, welding a plurality of cut parts to form a thermal expansion blank with a single rotary axis, sleeving the thermal expansion blank on the outer side of an expansion block of a thermal expansion forming die, performing thermal expansion on a thermal press, and finishing the end face to obtain the outer wall section. The titanium alloy thin-wall cylinder part with the angle of the rotation center line obtained by the invention has the advantages of good formability, high precision, no rebound and no residual stress.

Description

Thermal expansion forming die and forming method for titanium alloy thin-wall barrel part with angular rotation center line

Technical Field

The invention belongs to the field of machining, and particularly relates to a thermal expansion forming die and a forming method for a titanium alloy thin-wall cylinder part with an angle-shaped rotation center line of an aero-engine.

Background

As shown in figure 1, the part material of the outer wall section of the aircraft engine is a titanium alloy part, the wall thickness is t (t is less than or equal to 5 mm), the formed outer wall section 1 is a thin-wall cylindrical part (D2 = 2R) formed by transition of a cylindrical section with the diameter of D2 at the lower end and a conical section with the small diameter of D1 at the upper end through a spherical surface SR, the distance from the low point of the end surface of the outer wall section 1 to the bottom surface of the cylindrical section of the lower end D2 is Hmin, and the distance from the high point of the end surface of the outer wall section 1 to the bottom surface of the cylindrical section of the lower end D2 is Hmax. The included angle between the cylindrical section and the rotation center line of the conical section is alpha. The technical conditions of the parts require that no more than 6 longitudinal welding seams are formed.

The titanium alloy has strong toughness, large viscosity, poor moisture and heat conductivity, small elastic modulus and strong chemical affinity at normal temperature, so that the titanium alloy part is difficult to form in the normal temperature environment. Because the included angle of the rotation center line of the part exists, all sections in the axial direction of the part are different, and the molded surface of the part is not easy to control by adopting the traditional thermal expansion forming method; the part has conicity, and the part is easy to move upwards during bulging; the bulging die usually causes the lower end of a part to be qualified in size and the upper end of the part to be larger or even out of tolerance in the bulging process due to the existence of friction force in the horizontal direction.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a thermal expansion forming die and a forming method for a titanium alloy thin-wall cylinder part with an angle of a rotation center line, so that the forming quality and precision of the titanium alloy part are improved.

The basic forming thought of the invention is as follows: through designing and manufacturing the special thermal expansion forming die, the modes of adding the guide block between the expansion block and the lower template, adding the limiting pin for preventing upward movement at the lower end of the molded surface of the expansion block, changing the stress point of the expansion block and the like are adopted, the defects existing in the expansion of the traditional expansion die are eliminated, and the titanium alloy part with the advantages of good formability, high precision, no resilience, no residual stress and the like is obtained.

The invention adopts the following technical scheme:

a titanium alloy thin-wall cylinder part thermal expansion forming die with a rotation center line at an angle comprises,

the upper end surface of the lower template is provided with a round hole and T-shaped grooves, the T-shaped grooves are distributed on a circumferential radial line which takes the center of the round hole as the center of a circle, and included angles of the centers of the adjacent T-shaped grooves are equal;

the first guide block and the second guide block are connected in the T-shaped groove in a sliding mode, and a scribed line is marked at one end of the first guide block;

the outer surface of each expansion block is consistent with the inner surface of the titanium alloy thin-wall cylinder part with the rotation center line at an angle, the inner surface of each expansion block is a conical surface, the number of the expansion blocks is more than or equal to two, the upper end surfaces of the two expansion blocks respectively mark a scribed line at the low point of the titanium alloy thin-wall cylinder part with the rotation center line at an angle and a scribed line at the high point, the upper end surfaces of the expansion blocks are also provided with round bosses, the lower ends of the expansion blocks are respectively connected with the first guide block and the second guide block through connecting pieces, and the outer surface of each expansion block is also provided with a positioning hole;

the limiting pin is inserted into the positioning hole of the expansion block;

the cone is inserted into the cone formed by the inner molded surfaces of the expansion blocks;

the first limiting ring is a circular ring-shaped part and is placed in the circular hole of the lower template;

the second spacing collar, the second spacing collar is the ring of boss is taken to the outer lane, and when the cone was pegged graft with the cone that the interior profile of a plurality of blooms formed, the second spacing collar cup jointed on the cone, and boss terminal surface on the second spacing collar and bloated piece up end contactless, the ring inner circle diameter of second spacing collar satisfies when the circular boss side surface on the bloated piece contacts with the interior surface contact of outer lane boss on the second spacing collar, and ring inner circle diameter is greater than the internal diameter of the circular boss of bloated piece on the second spacing collar.

Further, when a plurality of the bloated piece is gathered together and first guide block and second guide block touch the first spacing collar in the round hole along with first guide block and the round hole on the lower bolster, there is the separation clearance between the appearance face of adjacent bloated piece. The separation gap can ensure that the expansion block is folded in place.

Furthermore, the lower end face of the expansion block is provided with a weight reduction groove, and a reinforcing rib is arranged in the weight reduction groove.

Furthermore, the bulging surfaces of the plurality of bulging blocks are surfaces obtained by dividing the inner surface of the titanium alloy thin-wall cylinder part with the rotation center line at an angle by the equal center included angle, namely, the inner surface of the outer wall section is equally divided into a plurality of parts by the equal center included angle by taking the rotation center line of the part as the center.

A method for forming the titanium alloy thin-wall cylinder part with the rotation center line of the thermal expansion forming die at an angle comprises the following steps:

step 1, a titanium alloy plate is used as a blank, a plurality of identical curved surface hot-stretched parts with convex surfaces are processed through hot-stretch forming, and the convex surfaces of the hot-stretched parts at least comprise a first spherical surface with the same radius as the SR spherical surface on the outer wall section;

step 2, cutting each hot stretching part according to the same cutting path to obtain a plurality of completely identical cut parts comprising a first spherical surface;

step 3, splicing a plurality of cut parts and welding the cut parts along a splicing line to form a thermal expansion-shaped blank with a single rotary axis; it should be noted that, on the premise of ensuring that the thermal expansion blank can be normally sleeved into the thermal expansion forming die, the circumferential dimension of the welded thermal expansion blank cannot be too large, and enough expansion deformation must be reserved to ensure that the dimension of the expanded profile is the same as that of the outer wall section;

step 4, sleeving the thermal expansion blank on the outer side of the expansion block of the thermal expansion forming die and then performing thermal expansion;

and step 5, marking the part subjected to thermal bulging by using the scribed lines corresponding to the low points, the scribed lines corresponding to the high points and the scribed lines marked at one end of the first guide block on the bulging block subjected to thermal bulging in the step 4, and cutting the end face of the part subjected to thermal bulging by combining the height Hmin and the height Hmax to finally obtain the titanium alloy thin-wall cylinder part with the rotation center line at the angle. For example, a characteristic section of the outer wall section including the low point and the high point and passing through the axis of the cylindrical section in the outer wall section is obtained by a principle that the three points determine a plane by using a scribed line corresponding to the low point on the expansion block, a scribed line corresponding to the high point and a scribed line marked at one end of the first guide block, and the end face cutting is performed by determining an angle alpha by using the height Hmin and the height Hmax by taking the characteristic section as a reference. Three scribed lines (a low-point scribed line and a high-point scribed line on the two expansion blocks and a scribed line on the end face of the first guide block) are adopted to mark and identify the characteristic points of the part after the thermal bulging, so that the alignment work in the subsequent cutting of the end face is facilitated.

Further, in step 1, the hot-stretching die comprises a lower die plate, a male die, a blank holder and a female die, wherein:

the lower template is provided with a mandril hole;

the shapes of the top surface and the side surface of the male die are consistent with the inner surface of the hot stretching part, the male die is connected with the lower die plate through a fastener, and an avoidance groove is formed in the lower end of the side surface of the male die;

a gap is reserved between the inner ring of the blank holder and the male die, and the height of the blank holder after being lifted is higher than the top surface of the male die;

and the inner cavity and the lower end surface of the female die are consistent with the outer surface of the hot stretching part.

As an option, in the step 1, a hot-stretching die is installed on a workbench of a hot press, the position of a mandril hole of a lower template is consistent with the position of a mandril hole of the hot press, the mandril can jack up a blank holder to move up and down, the hot press and the hot-stretching die are heated to 600-800 ℃, the hot-stretching die is opened, the blank holder is moved up to be flush with the top surface of a male die, a blank material is placed on the blank holder, the outer end surface of the blank material is aligned with a material supporting plate, a part is pressed after preheating, the temperature is reduced after pressure maintaining, and the part is taken out and placed on a cooling pad for natural cooling when the temperature is reduced to 200-400 ℃.

As an alternative to this, the first and second,

in the step 2, a limiting hole corresponding to the positioning hole on the expansion block is machined in the cut part, or in the step 3, a limiting hole corresponding to the positioning hole on the expansion block is machined in the thermal expansion-shaped blank;

and in the step 4, the limiting pin is simultaneously inserted into the positioning hole on the expansion block and the limiting hole on the thermal expansion blank.

Alternatively, in the step 4, the cone in the thermal expansion forming die is taken out, the thermal expansion blank is sleeved after the expansion block is folded, the limit pin is simultaneously inserted into the positioning hole in the expansion block and the limit hole in the thermal expansion blank, and then the cone is installed.

Further, in the step 4, performing thermal bulging on a hot press, mounting a thermal bulging forming die on a workbench of the hot press, heating the hot press and the thermal bulging forming die to 600-800 ℃, starting the thermal bulging, maintaining the pressure for a period of time, and then cooling; when the temperature is reduced to 200-400 ℃, taking out the parts, and placing the parts on a cooling pad for natural cooling.

As an alternative to this, it is possible to provide,

in the step 1, before hot-drawing forming, sequentially brushing a Ti protective coating and a lubricating coating on the surfaces of the blank and the hot-drawing die;

and 4, before thermal expansion, sequentially brushing a Ti protective coating and a lubricating coating on the surfaces of the thermal expansion blank and the thermal expansion forming die.

The forming method and the die of the invention have the following characteristics:

(1) The stress point of an expansion block in a traditional expansion die is changed, a second limiting ring is designed, the second limiting ring is a circular ring with a boss on the outer ring, and when the expansion block expands to the limit position, the diameter of the inner ring of the circular ring on the second limiting ring and the diameter of the circular boss of the expansion block keep a gap (about 0.1-1 mm). At the moment, the expansion block is in a final state, the gap ensures that the second limiting ring does not radially act with the cone, and only the second limiting ring is in contact with the side surface of the circular boss of the expansion block (the side surface of the outer ring) through the surface of the inner ring of the boss in the radial direction to generate an acting force in the radial direction, so that the upper end of the expansion block is folded, the center of gravity of the expansion block is closer to the axis than that of a traditional expansion die, and the phenomenon of 'head turning' of 'larger size of the upper end and smaller size of the lower end' of a product cylinder part can be effectively prevented;

(2) The limiting pin is added, so that the expansion block is prevented from moving upwards in the thermal expansion process;

(3) The whole forming process is divided into two parts of hot stretching and hot bulging, the forming deformation is reasonably distributed, and the deformation stress generated in the forming is eliminated;

(4) Processing a part with a single rotation axis into parts with two rotation axes in a mode of cutting end faces, and accurately ensuring the included angle of a rotation center line;

(5) The cutting reference (respectively corresponding to the highest point, the lowest point and the bottom surface) is determined by the three scribed lines on the thermal expansion forming die, and the operation is simple and easy;

(6) A plurality of identical parts are formed through hot stretching, and then a hot bulging blank with a single rotation axis is formed through cutting and welding, the stress in the bulging process is uniform, and the hot bulging forming quality is guaranteed.

Compared with the prior art, the invention provides the thermal expansion forming die and the forming method for the titanium alloy thin-wall cylinder part with the angle-shaped rotation center line, so that the forming quality and precision of the titanium alloy part are improved, and the requirement of the development of an aero-engine is met.

Drawings

FIG. 1 is a front view of an outer wall section;

FIG. 2 is an isometric view of a hot-drawn part after a hot-drawing process;

FIG. 3 is a front view of a cut part cut in phantom on a hot drawn part;

FIG. 4 isbase:Sub>A cross-sectional view A-A of the part after cutting;

FIG. 5 is a front view of a heat expanded blank part;

FIG. 6 is a schematic view of a hot-stretch mold configuration;

FIG. 7 is a schematic view of a thermal expansion forming die;

FIG. 8 is an isometric view of the lower platen;

FIG. 9 is an isometric view of a first guide block;

FIG. 10 is an isometric view of a second guide block;

FIG. 11 is an isometric view of the expansion block;

in the figure, 1-outer wall section; 2-hot drawing the part; 3-cutting the part; 4-thermal expansion of the blank; 5, a lower template; 6, a male die; 7-blank holder; 8-a female die; 9-a lower template; 10-a first guide block; 11-a first stop collar; 12-a second guide block; 13-a limit pin; 14-expanding blocks; 15-a cone; 16-a second stop collar.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described herein is limited to the following embodiments, and various modifications, substitutions and alterations based on the common general knowledge and practice in the art without departing from the technical spirit of the present invention are included in the scope of the present invention.

As shown in fig. 1, for a titanium alloy thin-wall cylinder part with a rotation center line in an angle to be formed, fig. 1 shows the shape characteristics of an outer wall section 1 of the part, the part is made of a titanium alloy, the material thickness is t (t is less than or equal to 5 mm), the part is a thin-wall cylinder formed by transition of a cylindrical section with a diameter of D2 at the lower end and a conical section with a small diameter of D1 at the upper end through a spherical surface SR, the distance from a low point of an end surface of the outer wall section 1 to a bottom surface of the cylindrical section of the lower end D2 is Hmin, the distance from a high point of the end surface of the outer wall section 1 to a bottom surface of the cylindrical section of the lower end D2 is Hmax, and the included angle between the cylindrical section and the rotation center line of the conical section is alpha. The technical conditions of the parts require that no more than 6 longitudinal welding lines are required;

aiming at the titanium alloy thin-wall cylinder part with the rotation center line in an angle in the figure 1, the processing thought of the invention is as follows: hot forming and cutting are adopted, specifically, a plurality of same curved surfaces (the curved surfaces comprise spherical surfaces with the same radius as that of SR spherical surfaces in the outer wall section 1) are hot stretched firstly, blanks with a single rotation center (the rotation center of the cylindrical section) are formed by welding after cutting, then profiles (including cylindrical surfaces, spherical surfaces and conical surfaces) of the outer wall section 1 are formed by thermal expansion, and finally, the end surfaces are cut to obtain another rotation center (the rotation center of the conical section).

The hot-drawn blank is a square flat plate, the structure of the hot-drawn part 2 formed by drawing is shown in fig. 2, the shape of the convex surface of the hot-drawn part 2 is the same as the spherical surface SR on the outer wall section 1 or at least a part of the convex surface is the same as the spherical surface SR (for example, the convex surface simultaneously comprises the curved surfaces which are the same as the cylindrical surface, SR spherical surface and conical surface on the outer wall section 1, or the convex surface only comprises the curved surface which is the same as the SR spherical surface on the outer wall section 1, if the convex surface adopts the former, the deformation amount of the subsequent thermal bulging is relatively reduced, and if the convex surface adopts the latter, the deformation amount of the subsequent thermal bulging is relatively larger), then the hot-drawn part 2 is cut into the cut part 3 according to the position of the dotted line (cutting path) in fig. 2, and the dotted path in fig. 2 is obtained by a reverse pushing method, that the thermal bulging blank 4 in fig. 5 is equally divided into a plurality of parts along the circumferential surface, the equally divided single parts are used as templates to draw templates, and the cut parts 3 according to the cutting template, or the cut parts 3 are scribed on the hot-drawn.

The hot stretching die is shown in figure 6 and mainly comprises a lower template 5, a male die 6, a blank holder 7 and a female die 8, and the die is made of medium silicon molybdenum nodular cast iron.

Forming a mandril hole on the lower template 5 according to the mandril hole position of the hot forming equipment;

the top surface and the side surface of the male die 6 are consistent with the inner surface of the hot-stretched part 2, the scaling coefficient is calculated according to the die material and the linear expansion coefficient of TA15, and the scaling coefficient = 0.8-1; the male die 6 is connected with the lower die plate 5 through a fastener; the lower end of the side surface of the male die 6 is provided with a step to avoid the lifting of the ejector rod;

the side wall of the upper end of the inner ring of the blank holder 7 keeps a uniform clearance of 1-2 mm with the male die 6; the side wall of the lower end of the inner ring of the blank holder 7 and the male die 6 keep a uniform gap of 1-4 mm; the height of the blank holder 7 after being lifted is higher than the top surface of the convex die 6;

the shape of the inner cavity and the lower end surface of the female die 8 is consistent with that of the outer surface of the hot-stretched part 2, and the uniform clearance t1 is kept between the inner cavity and the molded surface of the male die 6, wherein t1= (1-1.5) t; and hoisting devices are arranged on the outer side surfaces of the female die 8 and the lower template 5.

The hot-drawn part 2 is cut into cut parts 3 (the front view is shown in fig. 3, the view A-A is shown in fig. 4) according to the dotted line position of fig. 2, and then six cut parts 3 are welded to obtainbase:Sub>A single-rotation-axis thermal expansion-shaped blank 4 (shown in fig. 5).

The thermal expansion forming die for thermal expansion is shown in figure 7 and comprises a lower template 9, a first guide block 10, a first limiting ring 11, a second guide block 12, a limiting pin 13, an expansion block 14, a cone 15 and a second limiting ring 16, wherein the die is made of medium silicon-molybdenum nodular cast iron;

the lower template 9 (see figure 8) is a circular plate, and a weight reducing hole is formed in the center of the circular plate; a step hole is formed in the center of the circular plate to place the first limiting ring 11; the circular plate is provided with T-shaped grooves along the diameter direction and is uniformly distributed along the circumferential direction; the hoisting shaft is cast on the outer side of the circular plate;

the first guide block 10 (see fig. 9) is a "T" shaped block connected to the expansion block 14 by a fastener and slidable in a radial direction in a "T" shaped groove of the lower die plate 9; a gap of 1-4 mm is kept between the first guide block 10 and the lower template 9; one end of the part is provided with a small step, the step is provided with a scribed line, and the scribed line corresponds to a high point or a low point of the part (or the expansion block 14) during assembly;

the first limit ring 11 is a circular ring and is placed in a step hole of the lower template 9, and the function of the first limit ring is to limit the distance of the expansion block 14 which contracts inwards along the radial direction;

the second guide block 12 (see fig. 10) is a "T" shaped block connected to the expansion block 14 by fasteners and slidable in a radial direction in a "T" shaped slot of the lower die plate 9; a gap of 1-4 mm is kept between the second guide block 12 and the lower template 9;

the limiting pin 13 is a waist-shaped pin, a corresponding waist-shaped hole is formed in the thermal expansion-shaped blank 4, and the limiting pin 13 is inserted into the waist-shaped hole of the thermal expansion-shaped blank 4 and the waist-shaped hole of the expansion block 14 to prevent the thermal expansion-shaped blank 4 from moving upwards in the expansion process;

the outer surface of the expansion block 14 (see fig. 11) is consistent with the inner surface of the outer wall section 1 (after extension), the scaling factor is calculated according to the die material and the linear expansion coefficient of TA15, and the scaling factor = 0.8-1; the top surfaces of the expansion blocks 14 corresponding to the high points and the low points of the outer wall section 1 are scribed; a bolt hole is formed in the top of the lifting device for lifting; a circular boss is arranged at the top; removing material inside the expansion block 14 from the bottom surface and adding reinforcing ribs; the segmentation expansion blocks 14 are uniformly distributed along the circumferential direction, and the segmentation gaps do not prevent the thermal expansion-shaped blank 4 from being placed and installed after the expansion blocks 14 contract inwards; the inner side of the expansion block 14 is a conical surface, the taper is 2-10 degrees, and the conical surface is attached to the cone 15 in the final die assembly state;

the cone 15 is a cone, the taper is consistent with that of the expansion block 14, and the cone is attached to the expansion block 14 in the final die assembly state; the top of the cone is a circular truncated cone; a weight reducing hole is formed in the middle of the cone 15; after the cone 15 is pressed down, the folded expansion block 14 is pushed out, and the bottom surface of the boss of the cone 15 stops moving after contacting the second limiting ring 16;

the second limiting ring 16 is a circular ring with a boss on the outer ring, when the expansion block 14 expands outwards to the limit position, the side surface of the circular boss on the expansion block 14 contacts with the inner surface of the boss on the outer ring of the second limiting ring 16, at the moment, the diameter of the inner ring of the circular ring on the second limiting ring 16 and the inner diameter of the circular boss of the expansion block 14 keep a gap of 0.1-1 mm (the gap is shown in fig. 7), so that radial acting force is applied to the side surface of the circular boss on the expansion block 14 at the inner surface of the boss on the outer ring of the second limiting ring 16, the upper end of the expansion block 14 keeps tightened, the lower end of the expanded outer wall section 1 is prevented from being qualified in size, but the size of the upper end is larger or even out of tolerance, the bottom surface of the boss does not contact with the surface of the expansion block 14, in order to ensure the precision of the final state of the die, only the second limiting ring 16 and the expansion block 14 can have a surface contact, and the contact surface is the circular boss end surface on the expansion block 14;

the method of forming the outer wall section 1 using the hot-drawing and hot-bulging forming die as described above, the forming steps being as follows:

1. blanking: blanking a titanium alloy part plate, wherein a blank is a square plate, and calculating the size of the plate by using the expanded size of the part and the machining allowance;

2. coating an oxidation resistant layer and a graphite layer: coating Ti1# protective layers (anti-oxidation coating for preventing titanium alloy parts from being oxidized at high temperature) on the upper surface and the lower surface of the blank and the working surface of the hot stretching die by using a brush, after the surfaces of the blank and the hot stretching die are dried at room temperature, coating a graphite aqueous solution lubricant on the surfaces of the blank and the die, and naturally drying at room temperature;

3. thermoforming: forming on a hot press machine, installing a hot stretching die on a workbench of the hot press machine, enabling the position of a mandril hole of a lower template 5 to be consistent with that of a mandril hole of the hot press machine, ensuring that the mandril can jack up a blank holder 7 to move up and down, heating the hot press machine and the hot stretching die to 600-800 ℃, opening the hot stretching die, moving the blank holder 7 up to be flush with the upper end face of a male die 6, placing a blank material on the blank holder 7, aligning the outer end face of the blank material with a material supporting plate, preheating for 10min, pressing a part, keeping the pressure at 20MPa, keeping the pressure for 10min, and then cooling; when the temperature is reduced to 200-400 ℃, taking out the hot stretching part 2, and placing the hot stretching part on a cooling pad for natural cooling;

4. removing graphite, and cleaning the hot stretching part 2;

5. cutting: cutting the hot-drawn part 2 into a cut part 3;

6. welding 6 cut parts 3 to obtain 1 thermal expansion blank 4;

7. coating an oxidation-resistant layer and a graphite layer: coating Ti1# protective layers (anti-oxidation coating for preventing titanium alloy parts from being oxidized at high temperature) on the upper surface and the lower surface of the thermal expansion type blank 4 and the working surface of a thermal expansion forming die by using a brush, coating a graphite aqueous solution lubricant on the surface of the thermal expansion type blank 4 and the working surface of the thermal expansion forming die after the surface of the thermal expansion type blank 4 and the working surface of the thermal expansion forming die are dried at room temperature, and naturally drying at room temperature;

8. loading a thermal expansion-shaped blank 4: taking out the cone 15, drawing in the expansion block 14, then sleeving the thermal expansion-shaped blank 4, inserting the limit pin 13, putting the limit pin into the cone 15, and expanding the expansion block 14 outwards by the cone 15 under the action of gravity until the expansion block cannot be pushed;

9. and (3) thermal bulging: performing bulging on a hot press, mounting a thermal bulging forming die on a workbench of the hot press, heating the hot press and the thermal bulging forming die to 600-800 ℃, pressing the die under the pressure of 2-20 MPa, maintaining the pressure for 5-20 min, and then cooling; drawing the expansion block 14 to take out the part after the temperature is reduced to 200-400 ℃, placing the part on a cooling cushion for natural cooling, and marking marks corresponding to the marks of the high points and the low points of the expansion block 14 and the marks of the scribed lines on the end surface of the first guide block 10 on the upper side of the surface of the part before the part is taken out so as to identify the positions of the high points and the low points of the part and facilitate the alignment when the upper end and the lower end of the part are cut;

10. removing graphite and cleaning parts;

11. trimming: and (3) cutting the upper end face and the lower end face of the part by combining the height Hmin and the height Hmax in the figure 1 and the position marks of the high point, the low point and the lower end marked on the part in the step (9) to obtain the outer wall section 1 with the rotation center in an angle.

Those matters not described in detail in the description of the invention are well within the knowledge of a person skilled in the art in the prior art. Although the illustrative embodiments of the present invention have been described in order to facilitate those skilled in the art to understand the present invention, it is to be understood that the present invention is not limited to the scope of the embodiments, and that various changes may be made apparent to those skilled in the art as long as they are within the spirit and scope of the present invention as defined and defined in the appended claims, and all changes that can be made by the inventive concept are protected.

Claims

1. The titanium alloy thin-wall barrel part thermal expansion forming die with the angle formed by the rotation center line is characterized in that: comprises the steps of (a) preparing a substrate,

the upper end surface of the lower template (9) is provided with a round hole and T-shaped grooves, the T-shaped grooves are distributed on a circumferential radial line taking the center of the round hole as the center of a circle, and included angles of the centers of the adjacent T-shaped grooves are equal;

the guide device comprises a first guide block (10) and a second guide block (12), wherein the first guide block (10) and the second guide block (12) are connected in a T-shaped groove in a sliding mode, and a scribed line is marked at one end of the first guide block (10);

the outer surface of each expansion block (14) is consistent with the inner surface of the titanium alloy thin-wall cylinder part with the rotation center line at an angle, the inner surface of each expansion block (14) is a conical surface, the number of the expansion blocks (14) is more than or equal to two, the upper end surfaces of the two expansion blocks (14) respectively mark a scribed line corresponding to the rotation center line at the low point of the titanium alloy thin-wall cylinder part with the angle and a scribed line corresponding to the high point, the upper end surface of each expansion block (14) is also provided with a circular boss, the lower end of each expansion block (14) is respectively connected with the first guide block (10) and the second guide block (12) through connecting pieces, and the outer surface of each expansion block (14) is also provided with a positioning hole;

the limiting pin (13) is inserted into the positioning hole of the expansion block (14);

the cone (15), the said cone (15) is inserted in the cone formed by inner profile of a plurality of blooms (14);

the first limiting ring (11) is a circular ring-shaped part and is placed in a circular hole of the lower template (9);

the second limiting ring (16) is a circular ring with a boss on the outer ring, when a cone (15) is spliced with a cone formed by inner molded surfaces of a plurality of expansion blocks (14), the second limiting ring (16) is sleeved on the cone (15), the boss end surface on the second limiting ring (16) is not contacted with the upper end surface of the expansion block (14), and the diameter of the inner ring of the second limiting ring (16) meets the condition that the diameter of the inner ring of the second limiting ring (16) is greater than the inner diameter of the circular boss of the expansion block (14) when the side surface of the circular boss on the expansion block (14) is contacted with the inner surface of the boss of the outer ring on the second limiting ring (16).

2. The titanium alloy thin-wall cylinder part thermal expansion forming die with the angle of the rotation center line as claimed in claim 1, characterized in that: when the expansion blocks (14) gather together towards the round hole in the lower template (9) along with the first guide block (10) and the second guide block (12) and the first guide block (10) and the second guide block (12) touch the first limiting ring (11) in the round hole, a separation gap is formed between the outer profiles of the adjacent expansion blocks (14).

3. The thermal expansion forming die for the titanium alloy thin-wall cylinder part with the angle of the rotation center line as claimed in claim 1, characterized in that: the lower end face of the expansion block (14) is provided with a lightening groove, and a reinforcing rib is arranged in the lightening groove.

4. A method for forming a titanium alloy thin-walled cylinder part with an angle of rotation of the center line of rotation of the thermal expansion forming die according to claim 1, which comprises the steps of: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

step 1, a titanium alloy plate is used as a blank, a plurality of identical curved surface hot-drawn parts (2) with convex surfaces are processed through hot-drawing forming, and the convex surfaces of the hot-drawn parts (2) at least comprise a first spherical surface with the same radius as the spherical surface SR on the outer wall section (1);

step 2, cutting each hot stretching part (2) according to the same cutting path to obtain a plurality of completely identical cut parts (3) comprising a first spherical surface;

step 3, splicing a plurality of cut parts (3) and welding the parts along splicing lines to form a thermal expansion blank (4) with a single rotary axis;

step 4, sleeving the thermal expansion blank (4) on the outer side of an expansion block (14) of the thermal expansion forming die of claim 1, and then performing thermal expansion;

and 5, marking the part subjected to thermal bulging by using the scribed lines corresponding to the low points, the scribed lines corresponding to the high points and the scribed lines marked at one end of the first guide block (10) on the bulging block (14) subjected to thermal bulging in the step 4, and cutting the end face of the part subjected to thermal bulging by combining the height Hmin and the height Hmax to finally obtain the titanium alloy thin-wall cylinder part with the rotation center line at the angle.

5. The method for forming the titanium alloy thin-walled cylinder part with the angle of the rotation center line according to claim 4, wherein the method comprises the following steps: in step 1, the hot-drawing die comprises a lower template (5), a male die (6), a blank holder (7) and a female die (8), wherein:

the lower template (5) is provided with a mandril hole;

the shapes of the top surface and the side surface of the male die (6) are consistent with the inner surface of the hot stretching part (2), the male die (6) is connected with the lower die plate (5) through a fastener, and an avoiding groove is formed in the lower end of the side surface of the male die (6);

a gap is reserved between the inner ring of the blank holder (7) and the male die (6), and the height of the lifted blank holder (7) is higher than the top surface of the male die (6);

and the inner cavity and the lower end face of the female die (8) are consistent with the outer surface of the hot-stretched part (2).

6. The method for forming the titanium alloy thin-wall cylinder part with the angle of the rotation center line according to claim 4, characterized in that: in the step 1, a hot stretching die is installed on a workbench of a hot press, the position of an ejector rod hole of a lower template (5) is consistent with that of a hot press ejector rod hole, the ejector rod can be used for jacking a blank holder (7) to move up and down, the hot press and the hot stretching die are heated to 600-800 ℃, the hot stretching die is opened, the blank holder (7) is moved up to be flush with the top surface of a male die (6), a blank material is placed on the blank holder (7), the outer end surface of the blank material is aligned with a material supporting plate, a part is pressed after preheating, the temperature is reduced after pressure maintaining, and the part is taken out and placed on a cooling pad to be naturally cooled when the temperature is reduced to 200-400 ℃.

7. The method for forming the titanium alloy thin-walled cylinder part with the angle of the rotation center line according to claim 4, wherein the method comprises the following steps:

in the step 2, a limiting hole corresponding to a positioning hole on the expansion block (14) is machined in the cut part (3), or in the step 3, a limiting hole corresponding to a positioning hole on the expansion block (14) is machined in the thermal expansion-shaped blank (4);

in the step 4, the limiting pin (13) is simultaneously inserted into the positioning hole on the expansion block (14) and the limiting hole on the thermal expansion-shaped blank (4).

8. The method for forming the titanium alloy thin-wall cylinder part with the angle of the rotation center line according to claim 7, characterized in that: in the step 4, the cone (15) in the thermal expansion forming die is taken out, the thermal expansion shaped blank (4) is sleeved after the expansion block (14) is folded, the limiting pin (13) is simultaneously inserted into the positioning hole on the expansion block (14) and the limiting hole on the thermal expansion shaped blank (4), and then the cone (15) is installed.

9. The method for forming the titanium alloy thin-wall cylinder part with the angle of the rotation center line according to claim 7, characterized in that: in the step 4, performing thermal bulging on a thermal press, mounting a thermal bulging forming die on a workbench of the thermal press, heating the thermal press and the thermal bulging forming die to 600-800 ℃, starting thermal bulging, maintaining the pressure for a period of time, and then cooling; when the temperature is reduced to 200-400 ℃, taking out the part, and placing the part on a cooling pad for natural cooling.

10. The method for forming the titanium alloy thin-wall cylinder part with the angle of the rotation center line according to claim 4, characterized in that:

in the step 1, before hot stretch forming, sequentially brushing a Ti protective coating and a lubricating coating on the surfaces of the blank and the hot stretch die;

and 4, before thermal expansion, sequentially brushing a Ti protective coating and a lubricating coating on the surfaces of the thermal expansion blank (4) and the thermal expansion forming die.