Cylinder or tube assembled by a new method of eliminating interference

Abstract

The present invention relates to a method for interference joining concentric cylinders, wherein the smaller cylinder (102) is not assembled into the larger cylinder (101), the method involving the use of an auxiliary cylinder in an assembly chamber (301), so that the interference is temporarily eliminated by isostatic pressing, and one cylinder is assembled into the other cylinder, thereby producing a thicker cylinder with interference joint. The pressure is released and the pressure is removed from the assembly chamber (301), and finally only two cylinders with interference joint are left. Three, ten or even more cylinders can be assembled in the same way, thereby assembling a thick cylinder that is pre-compressed on the inside and pre-stressed on the outside. Several cylinders with interference joints exert the same stress when subjected to maximum pressure, so that the cylinder is subjected to greater pressure than a single cylinder with the same total wall thickness, which usually has the maximum stress on the inside of the wall and the stress is reduced to a lower percentage at the outer edge.

Description

Technical Field

[0001] The present invention relates to a device for applying pressure to an object. Background Art

[0002] When a pressurized fluid is injected into a chamber or a thick-walled cylinder, the reaction stress inside the wall becomes larger toward the center side, while its strength decreases toward the periphery. If the stress is uniform at the maximum pressure, the cylinder will withstand a greater pressure.

[0003] Two tubular pipes are press-fitted because the smaller cylinder cannot be installed inside the larger cylinder (unless a tool is manufactured). These two tubular pipes cause the wall to apply prestress outward and compress inward, while the thick cylinder is not pressurized. A press-fitted cylinder can withstand a greater pressure than a non-press-fitted cylinder.

[0004] Today, press-fitted tubular pipes are manufactured, and when the larger cylinder is heated so that it expands or swells and / or the smaller cylinder is cooled so that it contracts, the interference fit is eliminated; in this way, the interference fit disappears, and the pipes can be assembled or joined by assembling the pipes into a single pipe. After returning to normal temperature, they tend to recover their dimensions but cannot recover the said dimensions, thus maintaining "by interference fit" or "interference fit".

[0005] The interference fit that temporarily disappears due to the influence of temperature change is indeed very small, and the inner diameter of the outer cylinder of the cylinders to be joined must be slightly smaller than the outer diameter of the inner cylinder. In addition, it is difficult to maintain the temperature difference for several minutes to assemble them or assemble a new cylinder into another already assembled cylinder. This material was used to manufacture Blakely guns more than 150 years ago.

[0006] The interference fit that temporarily disappears due to the influence of temperature change may be larger in order to join short parts and join them only once, for example, joining a gear or a railway wheel to an axle. However, it is impossible to tightly join a group of thin cylinders together by the interference fit generated by temperature change.

[0007] The first mechanism for obtaining high isostatic pressure is a thick-walled cylinder chamber, where the width of the wall is measured as a percentage of the cylinder diameter; obviously, the thicker the wall, the greater the pressure it can withstand. But when it becomes thicker, the difference in reaction stress between the inner edge and the outer edge of the chamber wall becomes larger, as Figure 2 can be seen from its description.

[0008] A method for obtaining a higher pressure than a thick-walled cylinder is the "spiral chamber": around the axis of the cylinder, several kilometers of calculated stress plates are joined together, which generates a pressure of up to 600 MPa, twice and three times higher than the pressure of a simple thick-walled chamber with a wall thickness of 30% of the cylinder diameter.

[0009] A serious drawback of the spiral chamber is that it cannot withstand axial reaction stresses, so large "yokes" must be installed outside it for external support to support the caps, which may be at both ends of the cylinder. Each time the chamber is loaded or unloaded, both ends of the cylinder must be fully displaced.

[0010] High-pressure processing (HPP) technology for preparing pasteurized foods or hot isostatic pressing (HIP) technology for metallurgical casting or defect elimination are well-known.

[0011] The HIP technology is not used at such high pressures and can only be used at pressures up to 300 MPa because it uses compressed heated gas (usually argon). In addition, the yokes and hydraulic cylinders required for the chamber closing mechanism make thermal processing more difficult.

[0012] The Blakely cannon was manufactured using the technology of joining by thermal interference because Blakely was the first to manufacture a cannon consisting of concentric tubes with different degrees of elasticity, where the inner tube has greater elasticity because it has to withstand greater pressure. Bands or rings were placed in a slightly conical heated tube so that when they cooled, they would contract and compress the heated tube, putting the cannon in an initial stress state. This enabled Blakely to manufacture very durable, large-caliber, lightweight cannons.

[0013] Only for experimental purposes, in the microscopic dimensions of a diamond anvil cell, pressures of 10 GPa, 100 GPa or even higher can be applied. Since it cannot be done on a natural scale and only thousands of basic studies have been carried out so far, it is expected to conduct applied research on new materials such as lightweight materials, super-hard and tough materials, electrical materials, superconducting materials, etc.

[0014] Multi-wall chambers are another way to generate high pressure, but it can be said that they are attempts at other inventions for the same purpose (see patent application CL 201902913 and patent application CL 201902988). However, a new technical solution has been found that overcomes the disadvantages of the previously mentioned applications and is based on a new joint due to isostatic interference.

[0015] A new type of isostatic interference joining method can be carried out to assemble two, ten or more cylindrical tubes of any size by interference fit, which is beneficial for the manufacture of ultra-high pressure chambers or multi-chambers. Description of the Drawings

[0016] Figure 1 Shows two tubular chambers inside the assembly chamber 301, where the pressure inside the assembly chamber changes the diameter of the tubular chambers because no pressure enters each tubular chamber. Each tubular chamber has a cylindrical tube (101, 102) to be assembled.

[0017] Details:

[0018] View of detail A (left side): Since there is no pressure between the two tubular chambers, the cylinder cannot be joined by interference fit.

[0019] View of detail B (right side): As the pressure in the assembly chamber increases, the inner diameter of the larger tubular chamber increases and the outer diameter of the smaller tubular chamber decreases, which allows one tubular chamber to be inserted into the other.

[0020] Figure 2 The cross-section of a thick-walled cylinder and the pressure P borne by it are shown A The stress generated; adjacent is a cylinder assembled by isostatic interference fit of 6 thin-walled cylinders with the same wall thickness and the same material, and the P borne by this cylinder B is greater than P A , and since it is pre-compressed and prestressed when not pressurized, the stress on all cylinders is the same.

[0021] Figure 3 The tubular pipe 101 to be assembled is shown, which is pre-assembled with a larger auxiliary pipe 201 to form a tubular chamber with annular caps 211 and 212.

[0022] Figure 4 The chamber of a plurality of interference-fitted cylinders is shown, such that the smaller-diameter cylinder is pre-compressed and the larger-diameter cylinder is prestressed, while the chamber is not pressurized. When the chamber is at maximum pressure, both the initially pre-compressed and prestressed cylinders are prestressed at maximum pressure. Detailed Description

[0023] The present invention relates to a method for joining two or more concentric cylinders (101, 102) by isostatic interference fit, which cylinders have a certain roughness or grooves so that they do not slide after assembly.

[0024] In particular, the method of the present invention includes a method for joining two or more concentric cylinder pipes (101, 102) by isostatic interference fit, wherein one or both of the cylinder pipes are cylinder pipes that have already been joined by interference fit, and by means of auxiliary cylinder pipes (201, 202), caps (211, 212, 213, 214) and a high-pressure assembly chamber (301), used as tools for the joining method by isostatic interference, and having elastic and structural guides for pushing one cylinder pipe into the other inside the assembly chamber (301).

[0025] For this purpose, two tubular chambers or auxiliary chambers must be prepared, as Figure 1As shown, these tubular chambers or auxiliary chambers are formed by one of the cylinders (101) to be joined to the auxiliary cylinder (201), and they are placed to be joined concentrically by two annular caps (111) and (112). One cylinder (101) is fitted into another auxiliary cylinder tube (201), where the distance between them does not exceed 15% of the radius, as Figure 3 shown.

[0026] The second tubular chamber is constructed to be slightly smaller than the previous one. Among them, the cylinder (102) to be joined by interference fit can have roughness or grooves on the outside, and the smaller auxiliary cylinder (202) can have roughness or grooves on the inside. As in the previous case, these roughnesses or grooves are joined by two caps (213 and 214). Under normal circumstances, the smaller assembled chamber will not enter the inner cylinder of the larger tubular chamber because they are in interference with each other.

[0027] The tubular chambers continuously withstand high pressure within the assembled chamber (301), so as to keep the inside of each tubular chamber between the caps free of pressure; such that in the larger tubular chamber, the inner diameter of the smaller cylinder increases by δ1, and in the smaller tubular chamber, due to the increased pressure in the assembled chamber, the outer diameter of the larger cylinder decreases by δ2.

[0028] If the dimensions of the tubular chambers when withstanding high pressure are such that the inner diameter of the larger tubular chamber is equal to or greater than the outer diameter of the larger cylinder of the smaller tubular chamber, the pressure interference disappears due to stress, and they can be assembled.

[0029] If the tubular chambers are subjected to forces that force them to displace the smaller tubular chamber into the larger tubular chamber, then when given pressure conditions and the diameters are forced to change, the smaller tubular chamber will enter the larger tubular chamber. It can be by gravity, or an elastic band can be arranged. When the interference disappears, the elastic band forces one tubular chamber into the other tubular chamber and smoothly accommodates the tubular chambers.

[0030] When the pressure in the assembled chamber decreases, the tubular chambers are tightly locked because they tend to return to their diameters. The stuck tubular chambers are removed and disassembled, leaving only the two cylinders joined by interference fit. Then, another cylinder is placed by interference and joined in the same way, and then another cylinder is placed until a cylinder composed of multiple concentric cylinders is formed. Then two caps are placed on the cylinder, and a chamber joined by isostatic interference fit is obtained.

[0031] It should be noted that the cylinders joined by interference fit are prestressed on the outside and pre-compressed on the inside when there is no fluid, but when the pressurized fluid enters the cylinders, the pre-compressed side becomes the compressed side and the stress becomes uniform.

[0032] This cylinder can withstand higher pressures than a simple thick-walled cylinder of the same material and size because when it is at maximum pressure, it generates the same force whether measured or calculated at points more central or more external to the wall, as Figure 2 shown.

[0033] There are alternatives for creating new joints through isostatic interference fits, which are variants of the tubular chamber and are assembled with one, two, or no auxiliary cylinders and caps that are circular in some cases and annular in others.

[0034] It should be noted that the chamber (301) does not require such a large pressure to create a joint through the interference fit of the tube, which can be used to manufacture another chamber designed to withstand high pressures. It is sufficient for the chamber (301) to apply enough pressure such that one of the cylinders to be joined is a thin-walled cylinder and is at maximum force during assembly.

[0035] Alternatively, a tubular chamber can be manufactured using only one cylinder to be joined, while the other cylinder to be joined neither contracts nor expands due to pressure, but the interference fit for the expansion of the smaller cylinder in the tubular chamber is eliminated.

[0036] To avoid the cylinders joined by interference fit from bending due to external pressure when under high external pressure, suitable internal supports are installed.

[0037] Example 1 uses a cylinder or a joint chamber for isostatic interference fit.

[0038] By manufacturing thick interference-fit cylinders, chambers can be easily created by adding solid caps, as Figure 4 shown. This cylinder can be used for the same purpose of making high-pressure pasteurized food, but is much simpler than the HHP system that requires a large pressure winding machine; or it can be applied to metallurgy by replacing the HIP system through a generating system.

[0039] Moreover, this cylinder can also be used as a cylinder for manufacturing a barrel body that is pre-compressed internally and prestressed externally; it is much better than a barrel body using thermal interference; in addition, it can be used for thin barrels with a diameter of Φ0.5 cm or thick barrels with a diameter of Φ50 cm.

[0040] In addition, it can be used in multi-chambers where applying ultra-high pressure is very beneficial, and a spiral chamber cannot be applied due to its external support yoke. It can further be used to produce hydrogen storage tanks made of cylinders joined by isostatic interference fit, which are superior to new spiral tanks without a yoke. It is necessary to produce different models for specific functions (pressure, size, temperature, etc.).

[0041] Reference Signs

[0042] 101, 102: Cylindrical tubes joined by interference fit

[0043] 201, 202: Auxiliary cylinder tubes

[0044] 211, 212, 213, 214: Annular cylinder caps

[0045] 301: Assembly room

Claims

1. A method for isostatic interference joining of two or more concentric cylindrical tubes (101, 102), wherein, One or two of the cylindrical tubes are cylindrical tubes that have been press-fitted, and are used as tools for the joining method by isostatic press-fitting through the auxiliary cylindrical tubes (201, 202), caps (211, 212, 213, 214), and the high-pressure assembly chamber (301). A force selected from the force provided by the elastic band and gravity is used to push one cylindrical tube into the other cylindrical tube inside the assembly chamber (301). It is characterized in that each pair or group of concentric cylindrical tubes (101, 201) and their respective auxiliary cylindrical tubes (102, 202) are each equipped with corresponding caps (211, 212), (213, 214), and the corresponding caps are welded or glued to form two auxiliary chambers or tubular chambers, one larger and one smaller, such that considering that no pressure enters the interior of the tubular chamber through the cap, the auxiliary chamber or tubular chamber bears the pressure of the liquid or gas in the assembly chamber (301); the two tubular chambers are configured such that when the pressure rises and as the pressure increases, the diameter of the cylindrical tube (101) of the larger tubular chamber increases and the diameter of the cylindrical tube (102) of the smaller tubular chamber decreases, the interference fit disappears, and the smaller tubular chamber can be assembled, slid, and inserted into the larger tubular chamber by the applied force, so that the assembly is carried out when the mechanism of this effect is activated, where the mechanism can be located inside or outside the tube with the smaller radius; after the sliding or adjustment occurs, the pressure in the assembly chamber (301) is released from the installed cylindrical tubes, the diameter changes, and the cylindrical tubes (101 and 102) joined by the interference fit tend to return to the initial diameter; the auxiliary cylindrical tubes (201, 202) are removed, and only the two cylindrical tubes are joined together by the interference fit.

2. The method according to claim 1 for joining two or more concentric cylindrical tubes (101, 102) by isostatic interference fit, characterized in that, Prepare a pair of capped cylindrical tubes (101, 201), and also prepare another cylindrical tube (102) with a round cap or without a cap, and the interference fit occurs between the cylindrical tubes (101 and 102); wherein, the pressure in the assembly chamber (301) eliminates the interference fit, then the cylindrical tube (102) slides into the other cylindrical tube (101), the pressure in the assembly chamber is reduced, and the auxiliary cylindrical tube and the cap are disassembled, and the cylindrical tubes are finally joined together by the interference fit.

3. The method according to claim 1 for joining two or more concentric cylindrical tubes (101, 102) by isostatic interference fit, characterized in that, Prepare a pair of capped cylindrical tubes (102, 202), and also prepare another cylindrical tube (101) without a cap; the interference fit also occurs in the cylindrical tubes (101 and 102); the pressure eliminates the interference fit, then the cylindrical tube (102) slides into the other cylindrical tube (101), the pressure in the assembly chamber (301) is reduced, and the auxiliary cylindrical tube and the cap are disassembled, and the cylindrical tubes are finally joined together by the interference fit.

4. A method for joining two or more concentric cylindrical tubes (101, 102) by isostatic interference fit according to claim 1, characterized in that, Prepare a cylindrical tube (102) with a round cap, and also prepare another cylindrical tube (101) without a cap; the pressure eliminates the interference fit, then the cylindrical tube (102) slides into the other cylindrical tube (101), the pressure in the assembly chamber (301) is reduced, the cap is disassembled, and the cylindrical tubes are finally joined together by the interference fit.

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