Technological method for manufacturing sectional material based on hydrostatic pressure

Abstract

The invention discloses a process method for manufacturing a profile based on hydrostatic pressure, which comprises the following steps: (1) drilling a counter bore at one end of a test piece, preparing a stamping cover corresponding to the counter bore, and cleaning for later use; (2) uniformly coating the outer surface of the test piece with a solid lubricating mixture to serve as a first stamping protection layer; (3) smearing the second layer with lubricating oil to obtain a to-be-stamped test piece; (4) loading the to-be-stamped test piece into a stamping die, adding water into the counter bore, and covering with a stamping cover; and (5) the stamping head is aligned with the stamping cover and the to-be-stamped test piece to be pressed into the stamping die, the pressure of the stamping head is adjusted to generate hydrostatic pressure in the to-be-stamped test piece to prepare the profile, and a profile product can be obtained after stamping is completed. The method is simple and high in efficiency, hydrostatic pressure and stamping are combined for machining to obtain a one-time formed product, and the problems of low efficiency, high cost and limited precision of a traditional machining technology (such as turning, milling and grinding) are solved.

Description

Technical Field

[0001] The present invention relates to a hydrostatic pressure forming method, in particular to a process for manufacturing profiles based on hydrostatic pressure. Background Art

[0002] Hydroforming is an advanced metal forming technology that involves disciplines such as material mechanics, mechanical engineering, and manufacturing technology. It uses fluid static pressure to form metal into complex geometric shapes in a closed mold. By regulating the microstructure of metal materials, this technology can significantly improve the mechanical properties of materials, such as increasing tensile strength and toughness, without changing the chemical composition of the materials. In addition, this technology can produce lightweight metal and specialty metal parts by precisely controlling forming parameters, which is of great significance to the aerospace, automotive, and electronics industries.

[0003] The future trends in manufacturing technology are digitalization, intelligence, and sustainability. Hydrostatic forming technology aligns perfectly with these trends. It enables precise manufacturing based on digital models, improving production efficiency and accuracy. It also enhances the level of intelligent production through real-time monitoring and adjustment of forming parameters. Furthermore, this technology generates no hazardous waste during the forming process, helping to reduce environmental pollution and aligning with sustainable development requirements.

[0004] The existing Chinese patent application (CN118357408A) discloses in its specification a composite forming die for titanium alloy disc shaft parts, comprising an upper die connected to the pressure output end of a servo hydraulic press, a lower die coaxially arranged directly below the upper die, the lower die fixedly connected to the rotary table of the servo hydraulic press, a core die coaxially arranged with the lower die is fixedly arranged on the top surface of the rotary table, a funnel-shaped forming die groove is opened in the lower die, a conical forming punch is fixedly arranged at the center of the bottom surface of the upper die, and the upper die and the lower die are molded together. Finally, a forming cavity with a "Y"-shaped cross-section is formed between the bottom surface of the upper die and the forming die groove; during the forming operation, the blank is placed in the top of the forming die groove, the upper die descends, and the forming punch forges the blank. After the blank is forged and deformed until it contacts the inner wall of the forming cavity, it undergoes positive and negative compound extrusion deformation in the forming cavity to fill the forming cavity, forming a pre-forged blank with the basic shape of the formed part with the shaft neck and the disc body integrated. Then the upper die maintains pressure, and the rotary table drives the lower die to rotate. The pre-forged blank undergoes radial-tangential bidirectional shear deformation under high hydrostatic pressure in the forming cavity. It can be seen that this is an improvement to the die, and the stamped finished product does not have an inner hole.

[0005] In addition, the existing hydrostatic pressure technology is used to push the ingot through the mold to obtain the molding material. There are also those used for hydrostatic molding, that is, the hydrostatic elastic mold is generally made of rubber, plastic, etc. When the powder is loaded into the mold, the uniformity of the powder loading has a certain influence on the density and shape of the product, so vibration is usually used to make the powder evenly filled in the mold. A sleeve with holes is tightly put on the outside of the sealed elastic mold, and then pressed. It can be seen that hydrostatic pressure technology has not been applied to stamping molding technology. Therefore, in response to the defects of the existing technology, a process method for making profiles based on hydrostatic pressure has been developed. Summary of the Invention

[0006] The purpose of the present invention is to address the defects of the prior art and provide a process for producing profiles based on hydrostatic pressure. The present invention uses a combination of hydrostatic pressure and stamping to obtain a one-time formed product, which solves the problem that the prior art cannot drill slender holes (holes with a diameter of less than 5 mm). The present invention is efficient in punching out profiles containing slender holes, requires low costs, and the length can be precisely controlled. The present invention supports the one-time forming of parts with complex shapes, significantly improves processing efficiency, and reduces the cost of using molds and tools.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0008] A process for producing a profile based on hydrostatic pressure, the process comprising the following steps:

[0009] (1) Preparation and cleaning of the specimen: Drill a countersink extending along the length of the specimen at the axis of one end of the specimen, and prepare a stamping cover corresponding to the countersink. Then clean the specimen and the stamping cover and set aside.

[0010] (2) Coating protective layer: The outer surface of the specimen is evenly coated with a solid lubricant mixture as the first stamping protective layer;

[0011] (3) Applying lubricating oil: After the first protective layer is applied, a second layer of lubricating oil is applied to obtain the specimen to be stamped;

[0012] (4) Die loading: Place the specimen to be stamped into the stamping die, fill the countersunk hole with water, cover it with a stamping cover, and press the stamping cover into the countersunk hole until its top surface is aligned with the end face of the specimen; use water to squeeze out the air in the countersunk hole.

[0013] (5) Stamping: Use the punching head of the stamping equipment to align the stamping cover and the specimen to be stamped and press them into the stamping die. The hydrostatic pressure applied to the specimen to be stamped is adjusted by the pressure of the punching head. After the stamping is completed, a molded product with the required specifications of the inner hole and the outer shape is obtained.

[0014] Furthermore, the solid lubricant mixture comprises the following raw materials in parts by weight: 1-2 parts of molybdenum disulfide and 10-20 parts of acetone. Molybdenum disulfide is added to acetone and mixed evenly.

[0015] Furthermore, the lubricating oil comprises the following raw materials in percentage: 80% to 90% palm oil and 10% to 20% stearic acid.

[0016] Furthermore, the stamping die includes an upper die, a lower die and a forming die, and the upper die and the lower die clamp and fix the forming die; the forming die is provided with a forming groove and a discharge port; the upper die is provided with a stamping groove, and the axes of the stamping groove, the forming groove and the discharge port are aligned and overlapped with each other; wherein, during stamping, the specimen is inserted into the stamping groove and extends to the forming groove.

[0017] Furthermore, the test piece and the stamping cover are both made of pure copper.

[0018] Furthermore, the diameter of the countersunk hole is 5 to 10 mm.

[0019] Furthermore, the other end of the test piece is chamfered, and the angle of the chamfer is 30° to 60°.

[0020] Furthermore, the specimen is a cylindrical structure.

[0021] Furthermore, the depth of the countersunk hole is 1 / 2 to 7 / 8 of the length of the specimen.

[0022] Furthermore, the stamping conditions are controlled, the stamping pressure is gradually increased, the maximum pressure is controlled below 1100 kN, and the extrusion ratio R is 4-5.

[0023] Furthermore, the inner diameter of the profile product is 2 to 5 mm.

[0024] The present invention has the following improvements over the prior art:

[0025] 1. The present invention can obtain a one-time formed profile by combining hydrostatic pressure with stamping, and the profile includes an inner hole and an outer shape. That is, a countersunk hole is opened in the test piece, the countersunk hole is filled with water, and then a cover is stamped on the countersunk hole cover. Then, the test piece is mounted on the stamping die and fixed, and then the test piece and the stamping cover are stamped with a punch. During the stamping process, the water in the countersunk hole is incompressible and will extend into the interior of the profile punched out of the test piece. When the stamping is completed, a one-time formed profile containing an inner hole and an outer shape is obtained, and it can be processed into a long hole profile with a smaller inner diameter and better forming. However, it is difficult to obtain a fine-pore profile product in one go with ordinary turning, milling, and grinding processes. Multiple processing and replacement of processing tools are required, and the process is complicated.

[0026] 2. This invention reduces reliance on expensive specialized equipment, eases capital burdens, simplifies production processes, improves efficiency, and significantly reduces production costs. This not only enables diverse profile designs to meet the specific needs of various industries, but also allows the production of profiles with complex geometries by precisely controlling pressure distribution during the forming process.

[0027] 3. The present invention can produce lightweight metal and special metal parts by precisely controlling molding parameters, which is of great significance to the aerospace, automobile manufacturing and electronics industries.

[0028] 4. Through research in the present invention, it was found that the inner hole forming effect is particularly excellent for the processing of copper profiles, and the inner hole forming diameter can be controlled below 5mm. Moreover, under high-pressure stamping, the inner hole is straight, without bending and twisting, and only has some burrs within the allowable range of micro-profiles. For example, the length of the test piece in Example 2 of the present invention is 80mm, and when the stamping stroke of the punch head is 40mm, the length of the profile obtained by stamping is 170mm. The extrusion ratio R can be 4 to 5. The inner hole of the profile obtained by stamping is 2mm, which can effectively overcome the defect that the existing technology cannot currently produce hollow profiles with elongated holes with a diameter of less than 5mm. Because the existing drill bit will produce a large swing when it is rotated when it is too long, it is impossible to accurately drill the inner hole, and in deep hole processing, it is difficult to input the cooling lubricant into the cutting area, which will affect the durability of the tool, and it is also difficult to remove chips in deep hole processing.

[0029] 5. The present invention only uses a punching machine to apply pressure to the water in the pre-prepared countersunk hole to generate hydrostatic pressure, thereby forming an inner fine-pore profile in one go, and the forming is good. There is no need to replace equipment during the processing process. It only needs to control and adjust the pressure applied by the punching machine. The operation is simple, the process is short, and the time is fast. It only takes 15 to 30 minutes to complete the punching of the inner straight hole profile. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0031] Figure 1 A schematic diagram of a hand-driven structure of a process method for manufacturing profiles based on hydrostatic pressure according to the present invention;

[0032] Figure 2 This is a schematic diagram of the shape and structure of the test piece of the present invention before stamping;

[0033] Figure 3The figure is a schematic diagram of the profile structure obtained after the test piece is stamped using the present invention. It should be noted that the profile is cut to view the inner hole of the profile. The inner hole diameter shown in the figure is 2 mm.

[0034] Figure 4 A graph showing the relationship between the stamping loading force and the deformation of the specimen during the stamping process of the present invention;

[0035] Names and serial numbers of components in the figure:

[0036] 1-punch head, 2-punch cover, 3-water, 4-bolt, 5-upper die, 6-lower die, 7-forming die, 8-discharge port, 9-punch groove, 10-solid lubricant mixture, 11-test piece, 12-forming groove, 13-finished product groove. DETAILED DESCRIPTION

[0037] In order to enable people skilled in the art to better understand the technical solutions in this application, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application.

[0038] Example 1:

[0039] The stamping die used in the present invention is as follows Figure 1 As shown in the figure, the stamping die includes an upper die 5, a lower die 6, and a forming die 7. The upper and lower dies 5 and 6 clamp and secure the forming die 7; the forming die 7 is provided with a forming groove 12 and a discharge port 8; the upper die 5 is provided with a punching groove 9, and the axes of the punching groove 9, the forming groove 12, and the discharge port 8 are aligned and coincide with each other. During stamping, the test piece 11 is inserted into the punching groove 9 and extends to the forming groove 12.

[0040] During the experiment, the specimen used was a copper specimen with a cylindrical upper part and a chamfered lower part. The angles could be 30°, 35°, 40°, 45°, 50°, 55° or 60°.

[0041] The process for producing profiles based on hydrostatic pressure of the present invention comprises the following steps:

[0042] (1) Preparation and cleaning of the specimen: Drill a countersink extending along the length of the specimen at the axis of one end of the specimen, and prepare a stamping cover corresponding to the countersink. Then clean the specimen and the stamping cover and set aside.

[0043] The available diameter specifications for the countersink are 5 to 10 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, and the depth of the countersink is 1 / 2 to 7 / 8 of the specimen length. The available depths can be 1 / 2, 3 / 5, 5 / 7 or 7 / 8 of the specimen length.

[0044] The countersunk hole does not penetrate the specimen, but is spaced apart from the closest end face. This creates a certain thickness between the bottom of the countersunk hole and the closest end face of the specimen. This allows the specimen to expand outward under the action of hydrostatic pressure and stamping, resulting in a profile with an internal hole and external shape. This also prevents water in the countersunk hole from piercing the specimen end face and spraying outward during the stamping process.

[0045] (2) Coating protective layer: The outer surface of the specimen is evenly coated with a solid lubricating mixture as the first stamping protective layer.

[0046] The first structure of the solid lubricant mixture may be: 1 part of molybdenum disulfide and 10 parts of acetone.

[0047] The second structure of the solid lubricant mixture may be: 2 parts of molybdenum disulfide and 20 parts of acetone.

[0048] The third structure of the solid lubricant mixture may be: 1.5 parts of molybdenum disulfide and 15 parts of acetone.

[0049] Of course, the solid lubricant mixture is not limited to this, and appropriate amounts of molybdenum disulfide and acetone can be selected according to needs and within the prescribed range.

[0050] The preparation method of the solid lubricating mixture is as follows: take appropriate amounts of molybdenum disulfide and acetone respectively as required, then drop the acetone into the molybdenum disulfide until the molybdenum disulfide and acetone are fully blended.

[0051] (3) Applying lubricating oil: After the first protective layer is applied, a second layer of lubricating oil is applied to obtain the specimen to be stamped.

[0052] The first structure of the lubricating oil includes the following raw materials in percentage: 80% palm oil and 20% stearic acid.

[0053] The second structure of the lubricating oil includes the following raw materials in percentage: 90% palm oil and 10% stearic acid.

[0054] The third structure of lubricating oil includes the following raw materials in percentage: 85% palm oil and 15% stearic acid.

[0055] When using the lubricating oil, weigh the corresponding amounts of palm oil and stearic acid, then mix the palm oil and stearic acid evenly before use.

[0056] (4) Die loading: Place the specimen to be stamped into the stamping die, fill the countersunk hole with water, cover it with a stamping cover, and press the stamping cover into the countersunk hole until its top surface is aligned with the end face of the specimen. This prevents air from being trapped between the stamping cover and the water.

[0057] As you can understand, to ensure the stamped cover fits snugly over the countersunk hole, an annular groove is defined around the top of the countersunk hole. The depth of the groove is equal to the thickness of the stamped cover. When the stamped cover fits over the countersunk hole, the bottom surface of the stamped cover aligns with the bottom surface of the annular groove, and the top surface of the stamped cover aligns with the end face of the specimen.

[0058] (5) Stamping: Use the punching head of the stamping equipment to align the stamping cover and the specimen to be stamped and press them into the stamping die. The hydrostatic pressure applied to the specimen to be stamped is adjusted by the pressure of the punching head. After the stamping is completed, a molded product with the required specifications of the inner hole and the outer shape is obtained.

[0059] Example 2:

[0060] This embodiment uses the stamping die of Example 1 to stamp the test piece of this embodiment to prepare the profile. The test piece used is a pure copper cylinder, one end of which is provided with a countersink with a diameter of 5mm and the other end is chamfered with an angle of 45° (such as Figure 2 The test piece and the stamping cover are made of pure copper.

[0061] The process for producing profiles based on hydrostatic pressure comprises the following steps:

[0062] (1) Preparation and cleaning of specimens: Drill a countersink extending along the length of the specimen at the axis of one end of the specimen (e.g. Figure 3 As shown), the diameter of the countersink is 5 mm, the depth of the countersink is 3 / 4 of the length of the specimen, and a stamping cover corresponding to the countersink is prepared, and then the specimen and the stamping cover are cleaned and set aside;

[0063] (2) Protective layer coating: The outer surface of the specimen is evenly coated with a solid lubricant mixture as the first stamping protective layer. The solid lubricant mixture is prepared by fully mixing 2 parts of molybdenum disulfide and 20 parts of acetone.

[0064] (3) Applying lubricating oil: After the first protective layer is applied, a second layer of lubricating oil is applied to obtain the specimen to be stamped.

[0065] The lubricating oil comprises the following raw materials in percentage: 80% palm oil and 20% stearic acid. When used, the palm oil and stearic acid are thoroughly mixed.

[0066] (4) Die loading: Place the specimen to be stamped into the stamping die, fill the countersunk hole with water, cover it with a stamping cover, and press the stamping cover into the countersunk hole until its top surface is aligned with the end face of the specimen. This prevents air from being trapped between the stamping cover and the water.

[0067] (5) Stamping: Use the punch head of the stamping equipment to align the stamping cover and the specimen to be stamped and press them into the stamping die, and adjust the hydrostatic pressure applied to the specimen to be stamped by the pressure of the punch head. The stamping pressure is gradually increased (such as Figure 4 As shown), gradually increase to 1083kN, and control the extrusion ratio R to 5. After the stamping is completed, a profile product with a slender inner hole and an outer shape is obtained (as shown Figure 3 shown).

[0068] like Figure 3 As shown in the figure, the profile obtained after the specimen is stamped is a long cylindrical bar with an inner hole of 2mm. The length of the specimen is 80mm. After stamping, the stamping stroke of the punch head is 40mm (as shown in the figure). Figure 4 It can be seen that the length of the specimen is shortened to 40 mm, that is, the deformation of the specimen is 40 mm, and the length of the profile obtained by stamping is about 170 mm (such as Figure 3 As shown in the figure, the required stamping time is 20 minutes. It can be seen that the present invention can achieve a larger extrusion ratio, thereby achieving a larger deformation amount. It can also stamp out profiles faster, improving work efficiency.

[0069] The present invention combines hydrostatic pressure with stamping to effectively produce profiles containing elongated holes. Stamping the profiles takes 15 to 30 minutes, significantly improving work efficiency. However, existing drill bits that are too long produce significant oscillation during rotation, making it difficult to accurately drill internal holes. Furthermore, during deep hole drilling, cooling and lubricating fluids are difficult to deliver to the cutting zone, affecting tool durability. Furthermore, chip removal during deep hole drilling is difficult. This present invention effectively solves the existing technical problems associated with drilling elongated holes.

[0070] The solid lubricant used in this invention reduces friction and wear between the test piece and the mold and also offers high-pressure resistance. Molybdenum disulfide offers advantages such as good dispersibility, non-stick properties, and oxidation resistance. It can be added to various oils and fats to form a non-sticky colloidal state, thereby enhancing the lubricity and extreme pressure properties of the oil, making it suitable for high-temperature, high-pressure, high-speed, and high-load applications. Acetone has a strong dissolving power and can effectively clean and remove oil stains and contaminants from stamping equipment. This is crucial for maintaining cleanliness and proper operation of the equipment.

[0071] The beneficial effects achieved by mixing molybdenum disulfide with acetone include enhanced lubrication, improved surface treatment, and enhanced corrosion resistance. Molybdenum disulfide itself is an excellent solid lubricant, particularly effective in high-temperature, high-pressure environments. When mixed with acetone, the acetone's solvent action helps the molybdenum disulfide better penetrate the tiny pores on the metal surface, forming a more uniform lubricating film, thereby reducing friction and wear. The surface treatment effect can also be enhanced. The mixture of molybdenum disulfide and acetone can be used to clean and treat metal surfaces. The acetone's solubility helps remove oil and impurities from the metal surface, while the molybdenum disulfide forms a protective film on the cleaned surface, preventing metal oxidation and corrosion.

[0072] The solid lubricant mixture of the present invention is prepared by taking the required weight portions of solid lubricant, molybdenum disulfide, and acetone, first pouring a portion of the acetone into a stirring container, then gradually and evenly adding the molybdenum disulfide into the stirring container while stirring evenly; after the molybdenum disulfide is added, the remaining acetone is added, and stirring is continued for 3 to 5 minutes to obtain the lubricant mixture.

[0073] Palm oil has excellent lubricity and stability, providing stable lubrication during the stamping process, thereby protecting the mold and material surface. Palm oil also has a cooling effect, helping to dissipate heat during the stamping process, preventing mold overheating and extending the mold's lifespan. Stearic acid, as an emulsifier, effectively combines water and oil, making it easier to apply and improving the product's texture and stability. Its lubricating effect plays a vital role in extrusion and calendering. Its excellent lubricity and mold release properties reduce adhesion between the mold and the sheet metal, making it easier to release stamped parts from the mold and minimizing surface defects and mold wear. Stearic acid also improves the mold's corrosion resistance and extends its lifespan. When palm oil and stearic acid are mixed, the two easily combine, allowing for easy application to the surface of the test piece.

[0074] The present invention can process workpieces with high quality and large deformation amount and with inner and outer diameter specifications.

[0075] This invention utilizes a combination of hydrostatic pressure and stamping to produce a single-piece molded product. This overcomes the inefficiency, high cost, and limited precision inherent in traditional machining techniques (such as turning, milling, and grinding). This invention supports the single-piece molding of complex parts, significantly improving processing efficiency and reducing mold and tooling costs. Furthermore, by reducing cutting and grinding, material utilization is improved.

[0076] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A process for producing profiles based on hydrostatic pressure, characterized in that: The method comprises the following steps: (1) Preparation and cleaning of the specimen: a countersink extending along the length of the specimen is drilled at the axis of one end of the specimen, and a stamping cover corresponding to the countersink is prepared. The specimen and the stamping cover are then cleaned and set aside; (2) Coating a protective layer: The outer surface of the specimen is uniformly coated with a solid lubricant mixture as the first stamping protective layer; (3) Applying lubricating oil: After the first protective layer is applied, a second layer of lubricating oil is applied to obtain a test piece to be stamped; (4) Die loading: Place the specimen to be stamped into the stamping die, fill the countersunk hole with water, cover it with a stamping cover, and press the stamping cover into the countersunk hole until its top surface is aligned with the end surface of the specimen; (5) Stamping: Use the punching head of the stamping equipment to align the stamping cover and the specimen to be stamped and press them into the stamping die. The hydrostatic pressure applied to the specimen to be stamped is adjusted by the pressure of the punching head. After the stamping is completed, the profile product with the required specifications of the inner hole and the outer shape is obtained.

2. The process for producing profiles based on hydrostatic pressure according to claim 1, characterized in that: The solid lubricating mixture comprises the following raw materials in parts by weight: 1 to 2 parts of molybdenum disulfide and 10 to 20 parts of acetone.

3. The process for producing profiles based on hydrostatic pressure according to claim 1, characterized in that: The lubricating oil comprises the following raw materials in percentage: 80% to 90% of palm oil and 10% to 20% of stearic acid.

4. The process for producing profiles based on hydrostatic pressure according to claim 1, characterized in that: The stamping die comprises an upper die (5), a lower die (6) and a forming die (7); the upper die (5) and the lower die (6) clamp and fix the forming die (7); the forming die (7) is provided with a forming groove (12) and a discharge port (8); The upper die (5) is provided with a punching groove (9), and the axes of the punching groove (9), the forming groove (12), and the discharge port (8) are aligned and overlapped with each other; During stamping, the test piece (11) is inserted into the stamping groove (9) and extends to the forming groove (12).

5. The process for producing profiles based on hydrostatic pressure according to claim 1, characterized in that: The diameter of the countersunk hole is 5 to 10 mm.

6. The process for producing profiles based on hydrostatic pressure according to claim 1, characterized in that: The other end of the test piece is chamfered, the angle of the chamfer is 30° to 60°, and the test piece is a cylindrical structure.

7. The process for manufacturing profiles based on hydrostatic pressure according to claim 1, characterized in that: The stamping conditions are controlled, the stamping pressure is gradually increased, the maximum pressure is controlled below 1100 kN, and the extrusion ratio R is 4-5.

8. The process for manufacturing profiles based on hydrostatic pressure according to claim 1, characterized in that: The depth of the countersunk hole is 1 / 2 to 7 / 8 of the length of the test piece.

9. The process for manufacturing profiles based on hydrostatic pressure according to claim 1, characterized in that: The inner diameter of the profile product is 2 to 5 mm.

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