Cylinders or tubes assembled with new means to eliminate interference

Abstract

The present invention relates to a method of interference joining concentric cylinders, where the smaller cylinder (102) does not fit inside the larger cylinder (101), but involves the use of an auxiliary cylinder inside the assembly chamber (301), where the interference is temporarily eliminated by hydrostatic means and one cylinder fits inside the other, resulting in a thicker walled interference joined cylinder. The pressure is released and removed from the assembly chamber (301), leaving two interference joined cylinders. It is possible to assemble three or ten or more cylinders in the same manner to assemble thick walled cylinders that are pre-compressed on the inside and pre-stressed on the outside. Several interference joined cylinders will withstand higher pressures than a single cylinder of the same total wall thickness, exerting the same stress when the cylinders withstand maximum pressure, always reducing the stress from a maximum on the inside of the wall to a lower percentage at the outer edge.

Description

[Technical field]

[0001] The present invention relates to a device used to apply pressure to an object. [Background technology]

[0002] When a pressurized fluid is forced into a chamber or a thick-walled cylinder, the reaction stresses in the walls are greater towards the center and decrease in intensity towards the periphery. If the stresses were uniform at the maximum pressure, the cylinder would withstand a greater pressure.

[0003] Two cylindrical tubes are interference joined, but unless there is some mechanism, the smaller cylinder will not fit inside the larger one, so the walls are prestressed outwards and precompressed inwards, and the thick-walled cylinder is not under pressure. An interference joined cylinder will resist more pressure than a non-interference joined cylinder.

[0004] Today, interference-jointed cylindrical tubes are made and when the larger cylinder is heated to expand or dilate, and / or the smaller is cooled to contract, the interference is removed; thus the interference disappears and the tubes are assembled or joined as one tube. After the temperature is normally restored, they try to regain their dimensions and, since they cannot regain their dimensions, they remain "jointed by interference" or "interference-jointed".

[0005] The interference, which disappears temporarily under the influence of temperature changes, is very slight, and the cylinders to be joined must have an inner diameter of the outer cylinder slightly smaller than the outer diameter of the inner cylinder. Furthermore, it is difficult to maintain the temperature difference for the several minutes it takes to assemble them, or to assemble a new cylinder into another already assembled. This was used to manufacture the Blakely rifle more than 150 years ago.

[0006] The interference, which disappears temporarily under the effect of temperature changes, can be made larger for one-off joining of short sections, for example joining a gear or a railway wheel to an axle, but it is not possible to join a pair of thin-walled cylinders rigidly to each other with the interference achievable by temperature changes.

[0007] The first mechanism for achieving high hydrostatic pressure is a thick-walled cylindrical chamber, where the wall thickness is measured as a percentage of the cylinder diameter, and obviously the thicker it is the higher the pressure it can withstand, but as it gets thicker, there is a greater difference in reaction stresses between the inner and outer ends of the chamber wall, as can be seen in Figure 2 and its description.

[0008] A method of obtaining higher pressures than a thick-walled cylinder is the "coiled chamber": many kilometers of plates loaded with calculated stresses are bonded around the axis of a cylinder, which produces pressures of up to 600 MPa, i.e. two to three times higher than a thick-walled chamber of 30% of a single cylinder diameter.

[0009] Coiled chambers have the serious disadvantage of not being able to accommodate axial reaction stresses, and for external support a large "yoke" is attached to the outside to support the caps, which may be one at each end of the cylinder, which must be fully displaced each time the chamber is loaded or unloaded.

[0010] Well known are the high pressure processing (HPP technique) for preparing pressure sterilized foods or the hot isostatic pressing (HIP technique) used in metallurgy to make castings or to remove defects.

[0011] Since HIP technology uses compressed gas, usually heated argon, it cannot be used at very high pressures, up to 300 MPa at most. Furthermore, the yoke or hydraulic cylinder required for the closing mechanism of the chamber makes hot working more difficult.

[0012] The technique of thermal interference joints was used in the construction of Blakely cannon. He was the first to make cannon with coaxial tubes of different elasticity, the inner tube having the greater elasticity, which had to withstand the greater stress. Cords or rings were placed on the slightly conical red-hot tubes, which, when cooled, contracted and compressed, leaving the cannon at its initial stress. This enabled Blakely to make a very resistant, large-caliber, light cannon.

[0013] At microscopic size in diamond anvil cells, pressures of 10 or even 100 GPa or more have been applied only for experiments. Because it cannot be done at natural size, thousands of fundamental studies have only been carried out, and it is hoped that they will be followed by applied research in new materials, such as light materials, superhard and tough materials, electronic materials, superconducting materials, etc.

[0014] The multi-chamber is another way to generate high pressure, but it can be said to be an attempt of other inventions made for the same purpose (see Chilean applications CL201902913 and CL201902988).However, a new technical solution has been found that overcomes the drawbacks of the above mentioned applications and is based on a new bond by hydrostatic interference. Summary of the Invention

[0015] The new hydrostatic interference method is feasible and useful for assembling two or more cylindrical tubes of any size by interference, facilitating the production of ultra-high pressure chambers or multi-layer chambers. [Brief description of the drawings]

[0016] [Figure 1]FIG. 1 shows two tubular chambers in an assembly chamber 301, where pressure in the assembly chamber changes the diameter of the tubular chambers, since there is no pressure in each tubular chamber. Details: Detail A (left side): There is no pressure between the two tubular chambers, so the cylinders cannot be joined with interference. 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, allowing one tubular chamber to be inserted into the other.

[0017] [Diagram 2] Figure 2 shows a cross section of a thick-walled cylinder with the stresses generated by the pressure PA it withstands; adjacent to it is a cylinder assembled by hydrostatic interference joints, formed by six thinner cylinders of the same wall thickness and material, which withstand a PB greater than PA and have the same stresses in all cylinders as a result of precompression and prestressing when unpressurized.

[0018] [Diagram 3] 3 shows a cylindrical tube 101 to be assembled, which is pre-assembled with a larger auxiliary tube 201, thereby forming a tubular chamber with annular caps 211 and 212. Another tubular chamber has to be assembled with a smaller cylindrical tube 102, which comprises another auxiliary tube 202, which is smaller than the smaller cylindrical tube.

[0019] [Figure 4] Figure 4 shows a chamber of several interference-jointed cylinders, the smaller diameter cylinder being precompressed and the larger diameter being a prestressed, unpressurized chamber. When the chamber is fully pressurized, the cylinders that were initially precompressed and prestressed are all prestressed at their maximum pressure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention relates to a method for joining two or more concentric cylinders (101, 102) by hydrostatic interference, which have a certain roughness and fine grooves that prevent slipping once assembled.

[0021] For this purpose, two tubular or auxiliary chambers must be prepared, one of the cylinders (101) to be joined with the auxiliary cylinder (201) arranged concentrically joined by two annular caps (111 and 112) as shown in Figure 1. One cylinder (101) fits inside the other (201) and they are not separated by more than 15% of their radius, as shown in Figure 3.

[0022] The second tubular chamber is made a little smaller than the previous one, the cylinder (102) to be joined by interference may have a roughness or grooves on the outside, and the smaller auxiliary cylinder (202) may have a roughness or grooves on the inside, and is joined as in the previous case with two caps (113 and 114). Under normal circumstances, due to interference with each other, the smaller tubular chamber does not enter into the inner cylinder of the larger tubular chamber.

[0023] The tubular chambers are continuously exposed to high pressure in the assembly chamber (301), maintaining no pressure inside each tubular chamber between the caps; an increase in pressure in the assembly chamber increases the inner diameter of the smaller cylinder in the larger tubular chamber by δ1, and decreases the outer diameter of the larger cylinder in the smaller tubular chamber by δ2.

[0024] If the dimensions of the tubular chambers when exposed to 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, there will be no pressure interference and they can be assembled.

[0025] When the tubular chambers are exposed to a force that forces the smaller one into the larger one, and a pressure condition is applied to change diameter, the smaller tubular chamber will enter the larger tubular chamber, which can be by gravity or by elastic bands placed that force the tubular chamber into the other when the interference disappears, and is smoothly accommodated.

[0026] When the pressure in the assembly chamber is reduced, the tubular chambers are locked tight because they tend to return to their diameter. The fixed tubular chambers are removed and dismantled, leaving only the two cylinders with interference joints. Then, another cylinder with interference is placed and they are joined in the same way, then another one, and so on, until a cylinder is formed, with several concentric cylinders. Then, both caps are placed on them, resulting in a chamber joined by hydrostatic interference.

[0027] It should be noted that the interference-jointed cylinder is prestressed on the outside and precompressed on the inside in the absence of fluid, but as pressure fluid enters it, the precompressed side turns into a compressed side and the stresses become uniform.

[0028] This cylinder will withstand higher pressures than a single thick-walled cylinder of the same material and size because, at maximum pressure, it will exhibit the same stress whether measured or calculated at a more central point or at a more outer point on the wall as shown in FIG.

[0029] There are alternative means for creating new connections by hydrostatic interference, which are variations of tubular chambers, assembled with one or two auxiliary cylinders or without them, possibly with circular and other annular caps.

[0030] It should be noted that chamber (301) does not need to generate the significant pressure that can be employed to create interference joints of tubes to manufacture other chambers intended to withstand high pressures. Chamber (301) is sufficient to achieve maximum stress when one of the cylinders to be joined is a thin-walled cylinder and assembly is performed with sufficient pressure.

[0031] Alternatively, only one cylinder to be connected to produce a tubular chamber can be used, and the other cylinders to be connected can be neither compressed nor expanded, eliminating interference with the tubular chamber due to the expansion of the smaller cylinder.

[0032] To avoid buckling due to external pressure of the cylinders to be interference connected, if they are under high external pressure, suitable internal supports are provided. EXAMPLES

[0033] Example 1. Use of a cylindrical or bonded chamber for hydrostatic interference

[0034] By making a thick walled interference bonded cylinder, a chamber as shown in Figure 4 can be easily produced by adding a tight cap. It can be used for the same purpose of making high pressure pasteurized foods, but is much simpler than the HHP system which requires a large stress winder, or it can be applied in metallurgy by making a system to replace the HIP system.

[0035] It can also be used as a cylinder to make cannons that are precompressed inside and prestressed outside; much better than thermal interference cannons; and it can be used for thin cannons with diameters of 0.5 cm or thick cannons with diameters of 50 cm.

[0036] In addition, it is very advantageous to exert ultra-high pressure, and can be used in multi-chambers where coil chambers cannot be applied due to having an outer supporting yoke. It can also be used to make hydrogen storage tanks by cylinders joined by hydrostatic interference, which is better than the new coil tank without yoke. It is necessary to make different models for specific functions such as pressure, size, temperature, etc. [Explanation of symbols]

[0037] 101, 102: Cylinders joined by interference fit 201, 202: Auxiliary cylinder 211, 212, 213, 214: Annular cylindrical cap 301: Assembly chamber

Claims

**Claim 1** A method for joining two or more concentric cylindrical tubes (101, 102) by hydrostatic interference, wherein one or two of the cylindrical tubes may be cylindrical tubes that have already been interference - joined. As tools for the method of joining by hydrostatic interference, auxiliary cylindrical tubes (201, 202), caps (211, 212, 213, 214) and a high - pressure assembly chamber (301); inside the assembly chamber (301), a forcing means selected from an elastic band and gravity for pushing one cylindrical tube into the other is used; here, each pair or set of the concentric cylindrical tubes (101, 201) and their respective auxiliary cylindrical tubes (102, 202) are prepared together with their respective welded or adhered caps (211, 212), (213, 214) so as to be exposed to pressure by a liquid or gas within the assembly chamber (301), forming two tubular chambers, one larger and one smaller, and pressure does not enter inside the tubular chambers through the caps. Both of the tubular chambers are continuously placed by the forcing means. When the pressure rises and the interference disappears, the diameter of the cylindrical tube (101) of the tubular chamber with a larger pressure is increased and the diameter of the cylindrical tube (102) of the smaller tubular chamber is decreased, and by the forcing means, the smaller tubular chamber is fitted, slid and placed inside the larger tubular chamber. After sliding or adjustment is performed, the pressure in the assembly chamber (301) is released from the already - fitted cylindrical tubes, a change in diameter occurs, and the interference - joined tubes (101 and 102) tend to return to their original diameters; the auxiliary cylindrical tubes (201, 202) are removed, and only both cylindrical tubes are left joined by interference. **Claim 2** A pair of cylindrical tubes (101 and 201) with caps is prepared, another tube (102) with or without a cap is also prepared, and interference occurs between the tubes (101, 102); the pressure in the assembly chamber (301) removes the interference, then the cylindrical tube (102) slides into the other (101), the pressure in the assembly chamber is decreased and the auxiliary cylindrical tubes and the caps are removed, and the cylindrical tubes are finally joined by interference. The method according to claim 1. **Claim 3** A pair of cylindrical tubes (102 and 202) with caps are provided, and another tube (101) without a cap is also provided; interference occurs between tubes 101 and 102: pressure removes the interference, and then the cylindrical tube (102) slides into the other (101); the pressure in the assembly chamber (301) is reduced and the auxiliary cylindrical tube and the cap are removed, and the cylindrical tubes are finally joined by interference, the method according to claim 1.

4. A cylindrical tube (102) having an annular or circular cap is provided, and another tube (101) without a cap is also provided; pressure removes the interference, and then the cylindrical tube (102) slides into the other (101); the pressure in the assembly chamber (301) is reduced and the cap is removed, and the cylindrical tubes are finally joined by interference, the method according to claim 1.

5. A method of connecting two or more concentric cylindrical tubes by hydrostatic interference, the method comprising the following steps: a. Prepare at least two concentric cylindrical tubes, at least two caps welded or adhered to at least one of the concentric cylindrical tubes, and an assembly chamber, the at least two concentric cylindrical tubes are placed in the assembly chamber, the assembly chamber is provided with means for forcing one of the concentric cylindrical tubes into the other concentric cylindrical tube, the forcing means can be selected from gravity and elastic bands, and the one concentric cylindrical tube has a larger diameter than the other concentric cylindrical tube, b. Expose the at least two concentric cylindrical tubes to high pressure using a liquid or gas in the assembly chamber, c. Using the forcing means, the one concentric cylindrical tube is inserted into the other concentric cylindrical tube by the forcing means, d. Release the pressure in the assembly chamber, and e. Obtain at least two cylindrical tubes connected by hydrostatic interference.

6. The step a. further includes supplying at least one auxiliary tube, connecting the at least one auxiliary tube to one of the at least two concentric cylindrical tubes, the at least one auxiliary tube and one of the at least two concentric cylindrical tubes being coaxially aligned by the at least two caps, the at least two caps being annular caps, and the at least two caps further preventing the liquid or gas from entering between the at least one auxiliary tube and one of the at least two concentric cylindrical tubes, the method according to claim 5. **Claim 7**: The step a. comprises preparing a first auxiliary tube and a second auxiliary tube, and the at least two caps include four caps, the first auxiliary tube is connected to one of the concentric cylindrical tubes by two caps, and the second auxiliary tube is connected to the other concentric cylindrical tube of the concentric cylindrical tubes by the other two caps, and all the caps are annular caps, the method of claim 5. **Claim 8**: The method of claim 5, wherein two of the at least two caps are circular caps.

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