CN116475294B - A large-diameter, small-bending-radius thin-walled bend integral forming mold and method thereof - Google Patents
A large-diameter, small-bending-radius thin-walled bend integral forming mold and method thereofInfo
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- CN116475294B CN116475294B CN202310598856.2A CN202310598856A CN116475294B CN 116475294 B CN116475294 B CN 116475294B CN 202310598856 A CN202310598856 A CN 202310598856A CN 116475294 B CN116475294 B CN 116475294B
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- forming
- die
- liquid filling
- bending
- punch
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
- B21D26/033—Deforming tubular bodies
- B21D26/047—Mould construction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D37/00—Tools as parts of machines covered by this subclass
- B21D37/14—Particular arrangements for handling and holding in place complete dies
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Bending Of Plates, Rods, And Pipes (AREA)
Abstract
一种大直径小弯曲半径薄壁弯通整体成形模具及其方法，它涉及一种试验台。本发明为了解决现有技术存在大直径、小弯曲半径薄壁弯通管坯难以成形直壁段，内高压成形无法轴向补料，导致弯通外侧厚度减薄严重超差甚至开裂的问题。本发明的成形装置包括预成形装置和内高压成形装置。成形方法：步骤一：将推弯的管坯放入预成形模具成形出带有直壁段的预制管坯；步骤二：把预制管坯两侧的开口端切割成带一定角度的斜面，有效抑制胀形时外侧壁过度减薄，有效控制了整体的壁厚均匀性；步骤三：把切割后的预制管坯放入内高压成形模具成形，获得大直径、小弯曲半径薄壁弯通。本发明用于大直径小弯曲半径薄壁弯通整体成形。
A method for integral forming of a large-diameter, small-radius thin-walled bend is disclosed, which relates to a test bench. This invention addresses the problems in existing technologies where large-diameter, small-radius thin-walled bends are difficult to form straight-wall sections from the billet, and where axial material feeding is impossible during internal high-pressure forming, leading to severe thinning of the outer wall of the bend and even cracking. The forming apparatus of this invention includes a pre-forming device and an internal high-pressure forming device. The forming method is as follows: Step 1: The bent billet is placed into the pre-forming mold to form a pre-formed billet with a straight-wall section; Step 2: The open ends on both sides of the pre-formed billet are cut into bevels with a certain angle, effectively suppressing excessive thinning of the outer wall during bulging and effectively controlling the overall wall thickness uniformity; Step 3: The cut pre-formed billet is placed into the internal high-pressure forming mold to obtain a large-diameter, small-radius thin-walled bend. This invention is used for integral forming of large-diameter, small-radius thin-walled bends.
Description
Technical Field
The invention relates to a bending integral forming die and a method thereof, in particular to a large-diameter small-bending-radius thin-wall bending integral forming die and a method thereof.
Background
The metal thin-wall elbow is widely applied to industries such as aerospace, automobiles, ships and the like, such as pipeline systems of aerospace engines and large-scale gas turbines and the like. In order to meet the requirements of weight reduction, space utilization and high structural strength, integrally formed thin-wall bending with large diameter and small bending radius is always the preferred scheme of a designer. However, when the bending is formed by integral bending, the defects of excessive thinning of the outer side and wrinkling of the inner side are easy to occur, and the processing difficulty is extremely high.
In the prior art, a bent pipe blank is subjected to internal high-pressure forming, and the bent pipe blank is obtained mainly by push bending or numerical control winding. The tube blank formed by the numerical control bending (CNC bending) method has straight wall segments, but the diameter of the tube blank formed by the method is usually limited to less than phi 100mm, and a large-diameter thin-wall bent tube cannot be formed.
In the patent of CN 102554009A, a fluid pressure forming method for small radius elbow is proposed, after the numerical control is selected to bend around or push the elbow, the straight wall section is welded, then the diameter is increased and the bending radius is decreased by bulging to reduce the relative bending radius of the elbow, so that the thin wall small radius elbow is formed. According to the pipe blank, the straight wall sections are required to be welded, and the welding joint is easy to crack in a welding line and a heat affected zone due to poor tensile property during bulging, so that the formed sealing difficulty is improved, the welding line also influences the wall thickness distribution and the dimensional accuracy of a formed pipe fitting, and therefore, the method is complex in process and poor in finished product.
The invention patent with publication number CN 112091048A discloses a small bending radius bent pipe with straight sections at two ends, and a hydraulic forming device and a forming method thereof. According to the method, the numerical control bent pipe with the straight section is selected as the pipe blank for liquid filling bulging, so that the problems of outside cracking and inside wrinkling caused by the fact that a pipe with the straight section at two ends is formed by a traditional method are avoided. However, the diameter of the numerical control bent pipe blank is generally limited to be less than phi 100mm, and the problem of forming straight wall sections of large-diameter pipe blanks is difficult to solve.
Therefore, the prior art has the problems that the straight wall section of the thin-wall bent-through pipe blank with large diameter and small bending radius is difficult to form, the inner high-pressure forming cannot axially supplement materials, and the thickness of the outer side of the bent-through pipe is seriously thinned and is out of tolerance or even cracked.
Disclosure of Invention
The invention aims to solve the problems that in the prior art, a straight wall section is difficult to form in a large-diameter and small-bending-radius thin-wall bent pipe billet, and the thickness of the outer side of the bent pipe billet is seriously too poor and even cracked due to the fact that the inner high-pressure forming cannot be used for axially feeding. Further provides a large-diameter small-bending-radius thin-wall bending integral forming die and a method thereof.
The technical scheme is that the large-diameter small-bending-radius thin-wall bending integral forming die comprises an upper base plate, a lower die holder, a forming hydraulic cylinder, a liquid filling hydraulic cylinder, a forming cylinder seat, a liquid filling cylinder seat and a die body, wherein the upper base plate and the lower base plate are arranged in parallel up and down, the lower base plate is arranged on the lower die holder, the die body is arranged between the upper base plate and the lower base plate, the forming cylinder seat and the liquid filling cylinder seat are arranged between the upper base plate and the lower base plate, the forming hydraulic cylinder is arranged on the forming cylinder seat, the liquid filling hydraulic cylinder is arranged on the liquid filling cylinder seat, the forming hydraulic cylinder is connected with a forming punch of the die body, the liquid filling hydraulic cylinder is connected with a liquid filling punch of the die body, the die body comprises an upper concave die, a lower concave die, a forming punch and a liquid filling punch, the upper concave die and the lower concave die are buckled up and down, a U-shaped groove is formed between the upper concave die and the lower concave die, and the forming punch and the straight wall are respectively inserted in a section of the U-shaped groove in a sealing way.
Further, both ends of the U-shaped groove are in straight wall section shapes, the middle cavity shape of the U-shaped groove is in tube blank shape, and at the moment, the die body is a preformed die.
Further, the head diameters of the forming punch and the liquid filled punch that extend sealingly into the straight wall section taper.
Further, a boss is arranged on an upper female die in the preforming die.
Further, both ends of the U-shaped groove are in straight wall section shapes, the shape of a cavity in the middle of the U-shaped groove is a designed bent-through shape, and at the moment, the die body is an inner high-pressure forming die.
Further, both the forming punch and the liquid-filled punch are stepped punches.
Further, the heads of the forming punch and the liquid filling punch are embedded with sealing rings.
The invention also provides a forming method of the large-diameter small-bending-radius thin-wall bending integral forming die, which comprises the following steps:
Step one, putting the pushed bent tube blank into a pre-forming die, and forming a prefabricated tube blank with straight wall sections;
Cutting the open ends at two sides of the prefabricated pipe blank in the first step into inclined planes with a certain angle;
and thirdly, placing the cut prefabricated pipe blank into an inner high-pressure forming die for forming, and obtaining the thin-wall elbow with large diameter and small bending radius.
In the second step, the cutting angles of the open ends at the two sides of the prefabricated pipe blank are determined in the following manner:
cutting two ends of the preformed tube blank to obtain a design angle alpha, wherein the selection formula of the alpha is as follows:
Wherein D 0 is the diameter of the tube blank, D 1 is the designed bending diameter, R 0 is the bending radius of the tube blank, and R 1 is the designed bending radius.
Further, the forming of the prefabricated pipe blank in the third step in the inner high-pressure forming die B includes the following steps:
controlling a forming hydraulic cylinder and a liquid filling hydraulic cylinder to push a forming punch and a liquid filling punch, so that the outer side walls of inclined plane ports on two sides are deformed and stored preferentially;
step three, controlling the forming punch and the liquid filling punch to continuously push, and controlling the liquid filling hydraulic cylinder to carry out liquid filling pressurization to carry out internal high pressure forming;
Thirdly, controlling the liquid filling hydraulic cylinder to release pressure;
controlling the liquid filling punch to retract;
step three, lifting the upper female die and taking out the part;
and thirdly, cutting the bulging part to obtain the designed pipe.
Compared with the prior art, the invention has the following effects:
1. The application directly obtains the straight wall section on the large-diameter elbow through preforming, which is beneficial to sealing during bulging, meanwhile, the straight wall section can be fed by the axial pressure of the punch during bulging, the pipe material in a deformation area is increased, the flow of the pipe material during deformation is promoted, the axial feeding is facilitated, the excessive thinning of the outer side wall during elbow forming is avoided (the application adopts the following technical means that firstly, the pipe material in the deformation area is increased through the axial feeding of the pipe material during bulging of the straight wall section, and secondly, the punch preferentially pushes the outer side pipe material to store the pipe material during the early stage of bulging through ports with inclined surfaces on two sides, and the pipe material in the outer side deformation area is increased, so that the problem of even breakage is avoided, and meanwhile, the inner high-pressure bulging technology avoids the problem of easy wrinkling and instability during elbow forming (because the deformation area is bidirectional tensile stress during bulging, and wrinkling can be effectively inhibited compared with other technologies).
2. According to the invention, the port cutting strips at the two sides are provided with the inclined planes with the angle alpha through preforming, and during inner high-pressure forming, the preferential deformation and storage of the outer side pipe material (the preferential contact deformation of the outer side pipe material and the flat step punch head are carried out, so that the pipe material in the outer side deformation area is increased, and the outer side pipe material has good fluidity during subsequent bulging), thereby being beneficial to controlling the uniformity of the whole wall thickness of the bent pipe, and further reducing the risk of thinning and even cracking of the outer side wall.
3. The invention selects the large-diameter push bent pipe blank to directly form the straight wall section, overcomes the difficulty that the large-diameter bent pipe blank is difficult to form the straight wall section, reduces the difficulty of integral forming of the large-diameter small-bending-radius thin-wall bent pipe blank, and has the advantages of high forming quality, easiness in manufacturing the pipe blank, low process difficulty, simplicity in operation and the like.
4. The forming quality of the invention is high, and the invention is characterized in that firstly, the integral forming of the pipe fitting avoids welding seams (the traditional manufacturing method is half pipe deep drawing welding forming, and the integral performance is poor and the forming quality is low due to the existence of the welding seams). And the second point is that the wall thickness of the formed pipe fitting is uniformly distributed, excessive thinning and wrinkling thickening are avoided, the service environment with strict requirements on the wall thickness is favorably met, the material consumption can be reduced by accurate forming, and the integral light weight is favorably realized. And the third point is that the surface quality of the formed pipe fitting is high, the pipe material is subjected to bidirectional tensile stress during hydraulic bulging, wrinkling during forming is avoided, and meanwhile, the problem that scratches are easily formed on the surface during forming of the bent pipe fitting is avoided.
Drawings
Fig. 1 is a process flow diagram of the present invention. Fig. 2 is a schematic diagram of a change in the state of the elbow preparation.
Fig. 3 is a schematic view of a preform mold. Fig. 4 is a schematic view of an internal high pressure forming die. FIG. 5 is a schematic diagram of the overall structure of a large diameter, small bend radius thin wall, through-bend, integral forming die.
Detailed Description
In the first embodiment, referring to fig. 3 to 5, a large-diameter small-bending-radius thin-wall bending integral forming die of the first embodiment comprises an upper base plate 1, a lower base plate 2, a lower die holder 3, a forming hydraulic cylinder 4, a liquid filling hydraulic cylinder 5, a forming cylinder holder 6, a liquid filling cylinder holder 7 and a die body, wherein the upper base plate 1 and the lower base plate 2 are arranged in parallel up and down, the lower base plate 2 is arranged on the lower die holder 3, the die body is arranged between the upper base plate 1 and the lower base plate 2, the forming cylinder holder 6 and the liquid filling cylinder holder 7 are arranged between the upper base plate 1 and the lower base plate 2, the forming hydraulic cylinder 4 is arranged on the forming cylinder holder 6, the liquid filling hydraulic cylinder 5 is arranged on the liquid filling cylinder holder 7, the forming hydraulic cylinder 4 is connected with a forming punch of the die body, the liquid filling hydraulic cylinder 5 is connected with a liquid filling punch of the die body, the die body comprises an upper concave die 8, a lower concave die 9, a forming punch 10 and a liquid filling punch 11, the upper concave die 8 and the lower concave die 9 are buckled up and down, a U-shaped groove is formed between the upper die 8 and the concave die 9, the forming punch 10 and the liquid filling punch 11 are respectively inserted in a straight wall in the U-shaped groove in a sealing way.
In the second embodiment, the two ends of the U-shaped groove of the present embodiment are straight-walled sections, the middle cavity of the U-shaped groove is shaped as a tube blank, and the mold body is a preform mold a.
So arranged, for preforming the tube blank. Other compositions and connection relationships are the same as those of the first embodiment.
The upper backing plate 1 and the single-action press machine of the present embodiment are connected with bolts through T-shaped grooves, and the upper die 8 is mounted below the upper backing plate 1 through bolts. The cavity designs of the upper female die 8 and the lower female die 9 are mainly U-shaped grooves as shown in fig. 3, the cavity shape of the middle part of each U-shaped groove is a tube blank shape, and the two ends of each U-shaped groove are designed to be straight wall sections. The forming punch 11 and the forming punch 10 are mounted on the forming hydraulic cylinder 4 and the forming hydraulic cylinder 5 through bolts, the liquid filling pipe is connected with the forming punch 11 through bolts, the forming hydraulic cylinder 4 is mounted on the forming cylinder seat 6 through bolts, the liquid filling hydraulic cylinder 5 is mounted on the liquid filling cylinder seat 7 through bolts, and the forming cylinder seat 6 and the liquid filling cylinder seat 7 are fixedly connected with the lower backing plate 2 through T-shaped grooves and the bolts. The lower die 9 is arranged on the lower base plate 2, the lower base plate 2 is connected with the lower die holder 3 through a T-shaped groove and a bolt, and the lower die holder 3 is connected with the single-action press slide block through a T-shaped groove and a bolt.
Third, the present embodiment will be described with reference to fig. 3, in which the diameter of the head portion of the forming punch 10 and the liquid charging punch 11 which is sealed and inserted into the straight wall section is tapered. By the arrangement, the forming punch 10 and the liquid filling punch 11 can be conveniently and quickly extended into the tube blank, and the outer side walls of the forming punch 10 and the liquid filling punch 11 are used for forming the straight wall section with the corner at the stamping position of the tube blank between the straight wall section and the forming punch 10 and the liquid filling punch 11 in an inner high-pressure forming die under the stamping effect. Other compositions and connection relationships are the same as those of the first or second embodiment.
In the fourth embodiment, a boss 12 is provided on the upper die 8 in the preform mold a according to the present embodiment, as described with reference to fig. 3.
The boss 12 is arranged in such a way that the molded surface of the boss 12 is in the shape of the inner side wall of the preformed pipe blank, the size of the boss 12 is related to the size of the straight wall section and the size of the final formed pipe fitting, the arc line size of the molded surface of the boss 12 is larger than the arc line size of the inner side wall of the final formed pipe fitting, and the sum of the arc line size of the molded surface of the boss 12 and the length size of the straight wall sections on the two sides is the arc line size of the inner side wall of the pipe blank, so that the size of the boss 12 needs to be reduced as much as possible after the size requirement of the final formed pipe fitting is met, the size of the straight wall section is increased, and the purpose is to facilitate axial feeding and bulging sealing.
Other compositions and connection relationships are the same as those of the first, second or third embodiments.
In a fifth embodiment, referring to fig. 4, both ends of the U-shaped groove of the present embodiment are straight-wall sections, and the shape of the cavity in the middle of the U-shaped groove is a designed curved shape, and in this case, the mold body is an inner high-pressure forming mold B.
The arrangement is such that it is convenient to shape a tube blank which has been cut to form an inclined surface with a certain angle. Other compositions and connection relationships are the same as those of the first, second, third or fourth embodiments.
In a sixth embodiment, a description will be given of the present embodiment with reference to fig. 4, in which the forming punch 10 and the charging punch 11 are both stepped punches. The arrangement is convenient for providing the bent pipe which ensures that the punched pipe wall is of a designed size. Other compositions and connection relationships are the same as those in any one of the first to fifth embodiments.
In a seventh embodiment, a seal ring is embedded in each of the heads of the forming punch 10 and the charging punch 11 according to the present embodiment, as described with reference to fig. 4.
So set up, this sealing washer has guaranteed to realize sealedly in the punching press process. Other compositions and connection relationships are the same as those in any one of the first to sixth embodiments.
The first, fifth and seventh embodiments form an inner high pressure forming die B together, wherein the upper mat 1 and the single action press are connected to a bolt through a T-shaped groove, and the upper die 8 is mounted below the upper mat 1 through a bolt.
The cavity designs of the upper die 8 and the lower die 9 are shown as a U-shaped groove in fig. 4, the cavity shape of the middle part of the U-shaped groove is designed in the shape of a pipe material, and the two ends of the U-shaped groove are designed straight wall sections.
Eighth embodiment: the molding method according to the present embodiment is described with reference to fig. 1 and 2, and is characterized by comprising the steps of:
firstly, placing a bent tube blank into a pre-forming die A, and forming a prefabricated tube blank with straight wall sections;
Cutting the open ends at two sides of the prefabricated pipe blank in the first step into inclined planes with a certain angle;
and thirdly, placing the cut prefabricated pipe blank into an inner high-pressure forming die B for forming, and obtaining the thin-wall elbow with large diameter and small bending radius.
In the embodiment, the purpose of the first preforming step is to obtain a prefabricated pipe blank with a straight wall section, so that the sealing and axial feeding of subsequent inner high-pressure bulging are facilitated, the outer side wall is restrained from being thinned during inner high-pressure forming, and the problem that the sealing is difficult for large-diameter pipe fitting in high-pressure forming without the straight wall section is solved;
cutting the open ends at two sides along the inclined plane to facilitate the prior deformation storage of the outer side wall of the inner high-pressure forming, further inhibit the thinning of the outer side wall during the inner high-pressure forming and control the uniformity of the whole wall thickness;
and thirdly, performing internal high-pressure forming on the prefabricated pipe blank, wherein the purpose is to increase the pipe diameter of the deformed part and reduce the bending radius to form a large-diameter small-bending-radius target bend.
The method effectively solves the problem that the large-diameter push-bent pipe blank is difficult to seal during high-pressure bulging, effectively solves the problem that the inner high-pressure forming is difficult to axially supplement materials, effectively controls excessive thinning of the outer side wall in the forming process, effectively reduces the working pressure of the inner high-pressure bulging, and effectively inhibits wrinkling instability during pipe bending forming. The method has the advantages of good forming quality, high light weight level of the workpiece, high adjustable degree, good process stability and the like, and can greatly improve the overall performance of the part, reduce the manufacturing cost and shorten the production period.
In the first step of the embodiment, the preforming hydraulic cylinder is controlled to push the preforming punch and the preforming liquid filling punch, meanwhile, the preforming liquid filling pipe is filled with liquid for pressurization, and the hydraulic pressure in the pipe has a supporting effect on the pipe blank, so that the pipe blank is prevented from being unstable and wrinkled during preforming. The purpose is to directly form a straight wall section on a large-diameter pipe blank, the straight wall section is favorable for sealing and axial feeding of liquid filling bulging, excessive thinning and cracking of the outer side wall in the bulging process are avoided, and the uniformity of the wall thickness of the part is improved.
In the second step of the present embodiment, the open end cutting angle determination method for both sides of the preform is as follows:
cutting two ends of the preformed tube blank to obtain a design angle alpha, wherein the selection formula of the alpha is as follows:
Wherein D 0 is the diameter of the tube blank, D 1 is the designed bending diameter, R 0 is the bending radius of the tube blank, and R 1 is the designed bending radius.
By the arrangement, the thinning of the outer side wall during the inner high-pressure forming is restrained, and the uniformity of the whole wall thickness is controlled. Because the wall thickness distribution of the tube blank is uneven, and the wall thickness distribution of the pushing and bending tube blank of technological parameters such as different materials, friction coefficients, mould gaps, relative bending radius and the like are inconsistent, different cutting angles alpha can be selected for different tube blanks through calculation, and the wall thickness distribution required by the design of the final formed part is met by controlling the preferential deformation and storage of the outer side wall. The thickness distribution of different pipe fittings can be controlled by controlling the angle, so that the problem that the difficult-to-deform material is low in ductility and easy to crack can be avoided, the forming difficulty of difficult-to-form parts can be reduced, and the high uniformity requirement of the pipe fittings in an extreme service environment can be met. Other compositions and connection relationships are the same as those in any one of the first to eighth embodiments.
In a tenth embodiment, the method of forming the preform in the third step of the present embodiment in the inner high pressure forming die B includes the steps of:
step three, controlling a forming hydraulic cylinder 4 and a liquid filling hydraulic cylinder 5 to push a forming punch 10 and a liquid filling punch 11, so that the outer side walls of inclined plane ports on two sides are deformed and stored preferentially;
Step three, controlling the forming punch 10 and the liquid filling punch 11 to continue to advance, and controlling the liquid filling hydraulic cylinder 5 to carry out liquid filling pressurization to carry out internal high pressure forming;
Thirdly, controlling the liquid filling hydraulic cylinder 5 to release pressure;
controlling the liquid filling punch 11 to retract;
step three, lifting the upper female die 8 and taking out the part;
and thirdly, cutting the bulging part to obtain the designed pipe.
So configured, the rate of advancement is related to the magnitude of the hydraulic pressure, which is related to the deformation of the tubing. In general, during bulging, the axial feeding is needed to be performed by controlling the advancing speed of the punch, so that the flow of pipe materials is promoted, the uniformity of the whole wall thickness is improved, and excessive thinning and cracking are avoided. Other compositions and connection relationships are the same as in any one of the first to ninth embodiments.
While the invention has been described with reference to the preferred embodiments, it is not intended to limit the invention, but rather to cover various modifications which may be made by those skilled in the art without departing from the spirit of the invention.
Claims (7)
1. A large-diameter small-bending-radius thin-wall bending integral forming die is characterized by comprising an upper base plate (1), a lower base plate (2), a lower die holder (3), a forming hydraulic cylinder (4), a liquid filling hydraulic cylinder (5), a forming cylinder seat (6), a liquid filling cylinder seat (7) and a die body,
The upper padding plate (1) and the lower padding plate (2) are arranged in parallel up and down, the lower padding plate (2) is arranged on the lower die holder (3), the die body is arranged between the upper padding plate (1) and the lower padding plate (2), the forming cylinder seat (6) and the liquid filling cylinder seat (7) are arranged between the upper padding plate (1) and the lower padding plate (2), the forming hydraulic cylinder (4) is arranged on the forming cylinder seat (6), the liquid filling hydraulic cylinder (5) is arranged on the liquid filling cylinder seat (7), the forming hydraulic cylinder (4) is connected with the forming punch (10) of the die body, and the liquid filling hydraulic cylinder (5) is connected with the liquid filling punch (11) of the die body;
The die body comprises an upper female die (8), a lower female die (9), a forming punch (10) and a liquid filling punch (11), wherein the upper female die (8) and the lower female die (9) are buckled up and down, a U-shaped groove is formed between the upper female die (8) and the lower female die (9), the forming punch (10) and the liquid filling punch (11) are respectively and hermetically inserted in a straight wall section of the U-shaped groove, and the die body comprises a pre-forming die (A) and an inner high-pressure forming die (B);
The two ends of the U-shaped groove are in straight wall section shape, the shape of the middle cavity of the U-shaped groove is a tube blank shape, and at the moment, the die body is a preformed die (A), and a boss (12) is arranged on an upper female die (8) in the preformed die (A);
the two ends of the U-shaped groove are straight wall sections, the shape of the middle cavity of the U-shaped groove is a designed bending shape, and at the moment, the die body is an inner high-pressure forming die (B).
2. A large diameter small bending radius thin wall bending integral forming die as claimed in claim 1, wherein the head diameter of the forming punch (10) and the liquid filling punch (11) extending into the straight wall section in a sealing way is tapered.
3. A large-diameter small-bending-radius thin-wall bending integral forming die as claimed in claim 2, wherein the forming punch (10) and the liquid filling punch (11) are both stepped punches.
4. A large-diameter small-bending-radius thin-wall bending integral forming die as claimed in claim 3, wherein the heads of the forming punch (10) and the liquid filling punch (11) are embedded with sealing rings.
5. A forming method using the large-diameter small-bending-radius thin-wall bending-through integral forming die as claimed in any one of claims 1 to 4, characterized by comprising the following steps:
step one, putting the pushed bent tube blank into a pre-forming die (A) and forming a pre-formed tube blank with straight wall sections;
Cutting the open ends at two sides of the prefabricated pipe blank in the first step into inclined planes with a certain angle;
and thirdly, placing the cut prefabricated pipe blank into an inner high-pressure forming die (B) for forming, and obtaining the thin-wall elbow with large diameter and small bending radius.
6. The method for integrally forming a large-diameter small-bending-radius thin-wall elbow according to claim 5, wherein in the second step, the cutting angles of the open ends at both sides of the prefabricated pipe blank are determined in the following manner:
cutting two ends of the preformed tube blank to obtain a design angle alpha, wherein the selection formula of the alpha is as follows:
Wherein D 0 is the diameter of the tube blank, D 1 is the designed bending diameter, R 0 is the bending radius of the tube blank, and R 1 is the designed bending radius.
7. The method for integrally forming a large-diameter small-bending-radius thin-wall bend as claimed in claim 6, wherein the forming of the preform in the step three in the inner high-pressure forming die (B) comprises the steps of:
Step three, controlling a forming hydraulic cylinder (4) and a liquid filling hydraulic cylinder (5) to push a forming punch (10) and a liquid filling punch (11) so as to lead the outer side walls of inclined plane ports on two sides to deform and store materials preferentially;
Step three, controlling the forming punch (10) and the liquid filling punch (11) to continuously push, and controlling the liquid filling hydraulic cylinder (5) to carry out liquid filling pressurization to carry out internal high pressure forming;
thirdly, controlling the liquid filling hydraulic cylinder (5) to release pressure;
controlling the liquid filling punch (11) to retract;
step three, lifting the upper female die (8) and taking out the part;
and thirdly, cutting the bulging part to obtain the designed pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310598856.2A CN116475294B (en) | 2023-05-25 | 2023-05-25 | A large-diameter, small-bending-radius thin-walled bend integral forming mold and method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310598856.2A CN116475294B (en) | 2023-05-25 | 2023-05-25 | A large-diameter, small-bending-radius thin-walled bend integral forming mold and method thereof |
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| Publication Number | Publication Date |
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| CN116475294A CN116475294A (en) | 2023-07-25 |
| CN116475294B true CN116475294B (en) | 2026-01-30 |
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| JP2002282956A (en) * | 2001-03-27 | 2002-10-02 | Nippon Steel Corp | Hydroform processing method and apparatus |
| US8793850B2 (en) * | 2006-12-11 | 2014-08-05 | Witzenmann Gmbh | Method for producing a tube with a bent progression as a transverse progression |
| CN102554009B (en) * | 2011-12-26 | 2014-11-05 | 北京航空航天大学 | Fluid pressure forming method for small-radius elbow |
| JP2017051957A (en) * | 2015-09-07 | 2017-03-16 | ジョンソンコントロールズ ヒタチ エア コンディショニング テクノロジー（ホンコン）リミテッド | Manufacturing method for three-way branch pipe, three-way branch pipe, and metal mold |
| CN105598265A (en) * | 2015-12-21 | 2016-05-25 | 哈尔滨奔马科技有限公司 | Overall forming method of small-relative-bending-radius and large-diameter-thickness-ratio thin-walled bent pipe fitting |
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