Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/02—Making uncoated products
  • B21C23/20—Making uncoated products by backward extrusion
  • B21C23/205—Making products of generally elongated shape
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/02—Making uncoated products
  • B21C23/20—Making uncoated products by backward extrusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/21—Presses specially adapted for extruding metal
  • B21C23/218—Indirect extrusion presses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/32—Lubrication of metal being extruded or of dies, or the like, e.g. physical state of lubricant, location where lubricant is applied

Definitions

• the invention relates to the field of material forming, namely the method of production of high-pressure cylinder from corrosion-resistant steel using the method of hot backward extrusion solved completely specifically for the possibility to obtain high-pressure seamless cylinder not showing hydrogen embrittlement and inner surface corrosion.
• High-pressure seamless steel cylinders are currently produced using the method of backward extrusion and drawing utilizing the process according to the CZ pat 243247.
• steel blanks are first cut from billets of square or circular section.
• the steel blanks are heated in an induction furnace to the output temperature of 1000 to 1250 °C, after which they are robotically transposed into a descaling device where a high-pressure water jetting is performed to remove the scales from the surface of blanks.
• each individual blank is inserted by stacker into an extrusion press, where it is upset and backward extruded.
• the backward extrusion process is realized in two steps.
• the blank is inserted into a die with a vertically moving ram, cylindrical insert, and piercing mandrel fitted with a piercing head, where a thick- walled hollow semi-product, which is smooth inside without protrusions or bumps, is produced by means of extrusion from the blank.
• a thick- walled hollow semi-product which is smooth inside without protrusions or bumps, is produced by means of extrusion from the blank.
• bottom is pressed in the semi-product basically to the final thickness, however the semi-product has larger diameter than the final product.
• the semiproduct is robotically removed from the extrusion press, turned by 90°, and seated in this position into the horizontal drawing press, where the second step of forming, which is backward drawing, will take place.
• the semi-product is put on a drawing mandrel with the already final inner diameter of the cylinder, after which it is extruded through a stripper ring and roller cartridges fitted with reduction rollers.
• the semi-product on the mandrel is rolled, in which process reshaping of the semi-product wail thickness by approximately 25 % to 85 % will take place, and the semi-product will acquire the desired outer and inner diameter. In addition, the rest of scales will fall off.
• insertion of the semi-product bottom into a sizing die is performed, thus forming the final shape of the cylinder bottom.
• the semi-product is pulled off from the drawing mandrel with the help of stripping jaws.
• the stage of the semi-product processing by rolling is mentioned in the Utility model CZ U 20492.
• the hollow semi-products are aftercooled with air and subsequently necked, i.e. closed by means of rotary forming to create a steel cylinder of typical geometry.
• New method of manufacturing seamless high-pressure cylinder from corrosion-resistant steel is designed allowing the production of thin-walled seamless version of the cylinder from corrosion-resistant steel even for larger and high-volume high- pressure cylinders.
• the invention starts from the existing method of manufacturing seamless high- pressure cylinders.
• the starting part in the form of a steel blank is heated in an induction furnace and then inserted into an extrusion press where it is upset and backward extruded in two steps.
• the blank is inserted into a die with a cylindrical insert and a vertically moving piercing tool, and here it is moulded by means of extrusion until a thick-walled hollow semi-product having an inner cavity, walls and bottom is moulded from it.
• the semiproduct is removed from the extrusion press, turned by 90°, and seated in this position into a horizontal drawing press, where the second step of forming, which is backward drawing, takes place.
• the semi-product is put on a drawing mandrel with the diameter corresponding to the desired final inner diameter of the produced cylinder, while in this drawing press, the semi-product is extruded through a stripper ring and roller cartridges fitted with reduction rollers by means of which it is rolled on the mandrel. This rolling is performed so long until the semi-product acquires the desired outer and inner diameter corresponding to the required final dimensions of the produced cylinder. Then the final shape of the cylinder bottom is formed by insertion of the semi-product bottom into a sizing die and subsequently, in the course of the backward movement of the drawing mandrel, the semi-product Is pulled off from the drawing mandrel with the help of stripping jaws and is aftercooled.
• the semi-product manufactured in this way is necked, by which the shape of the manufactured cylinder is finished.
• the essence of the new solution according to the invention is that even before heating in the induction furnace, at least 85 % of the blank surface is coated with coating from material based on water glass with thickness of 20 to 150 ⁇ , this coating is cured by drying at the temperature of 15 to 60 °C and only after this curing, the blank is subjected to heating in the induction furnace.
• the material based on water glass is applied to the blank for example by spraying with nozzles or brushing in the form of water glass suspension.
• the water glass suspension stands here for suspension containing 20 to 40 % w. w. of sodium silicate or potassium silicate or mixture of these silicates, and 80 to 40 % w. w. of water, while in the case of presence of admixtures such as borosilicates and/or corrosion inhibitors, these admixtures are contained in the amount of maximum 20 % w. w.
• the blank with coating from materia) based on water glass is heated in the induction furnace to the temperature of 1180 °C to 1260 e C.
• the blank with coating is taken out of here, and during persistence of its temperature of minimum 1110 * C, it is inserted into the extrusion press, preferably without performing water descaling between the removal from the induction furnace and insertion into the extrusion press.
• the coating of material based on water glass is broken to pieces by purposeful pushing of the piercing tool to the blank, while it is cracking off during extrusion in the extrusion press until at least its major part is removed, meant as thickness of layer.
• the leftovers of coating based on water glass are preferably removed from the surface of the semi-product by pressure blasting of its outer as well as inner surface with abrasive.
• the blank is made preferably from corrosion-resistant steel while the resulting cylinder is made as a seamless cylinder in the volume range from 5 litres up to 260 litres, as a single necked or double-necked cylinder for any volume within the said range.
• Thin walled seamless high-pressure cylinders of the abovementioned volumes are preferably manufactured with the help of this invention.
• the semi-product wall is pressed to the thickness of 2 to 21.5 mm.
• the invention is utilizable for manufacturing of seamless high-pressure cylinders. It makes possible to manufacture these cylinders from corrosion- resistant steel and that in the corrosion-resistant version, even for larger and high cylinder volumes from 5 to 260 litres.
• the invention makes possible to manufacture these cylinders in the thin-wailed version from significantly wider range of high-strength corrosion-resistant steels than the existing methods. Using this invention, substantial reduction of the mass of high-pressure cylinders is achieved as compared to the present state of art, and savings of material for their production.
• the seamless thin-walled version with these volumes was not possible so far.
• the cylinders according to the invention exhibit high mechanical resistance as well as pressure resistance.
• the cylinders according to the invention are by as much as two thirds lighter.
• the option to use corrosion- resistant steel for the production makes possible to use these cylinders even for raw natural gas and for gases and mixtures that in the case of existing cylinders from common chrome-molybdenum steel are causing hydrogen embrittlement and accelerated corrosion when reacting with the gas under high pressure.
• Fig. 1 shows the blank with applied coating of water glass in cross-section
• Fig. 2 shows the phase of curing of the coating on the blank
• Fig. 3 shows the phase of relocation of the blank from the induction furnace directly into the extrusion press
• Fig. 4 A, B shows process of pressing of the blank in the extrusion press, from which A shows the phase of extrusion of the future cylinder cavity in the blank and B shows the subsequent phase of breaking and falling off of the coating from the semi-product during pressing.
• Example of embodiment of the invention is visually demonstrated with the help of Figs. 1 to 4 and the hereinafter-described method of production of corrosion- resistant high-pressure seamless cylinder for storage, transport, and use of natural gas.
• Parts of the size needed for the manufacture of cylinders of the produced volume are first cut from billets of corrosion-resistant steel having square or circular section.
• Each individual part i.e. the starting steel blank 1
• the thickness of applied layer is 20 to 150 ⁇ .
• Suspension usually called water glass is used as the material based on water glass.
• the suspension based on water glass stands for suspension containing 20 to 40 % w. w. of sodium silicate or potassium silicate or their mixture and 80 to 40 % w. w. of water.
• Admixtures of borosilicates and corrosion inhibitors such as hexamine, fenyiethylamine, phosphates, etc. and/or possible other admixtures can be contained provided they do not exceed the amount of 20 % w. w. in the suspension.
• This coating 2 can be applied by brushing or spraying. After the application, the coating is let to dry at the temperature of 15 to 60 °C until curing. Sufficient curing will not take place in the case of curing below the temperature of 15 °C, so that unwanted cracking and falling-off of the coating 2 layer would take place during subsequent heating in the induction furnace. In the case of curing above 60 °C, unwanted cracking of the coating 2 will take place as soon as during drying. During curing within the said range, creation of homogenous layer acting as a protective jacket on the surface of the blank 1 takes place. For the drying process or after it, the blank 1 is placed into the induction furnace, where it is heated up by gradual heating to the temperature of 1180 °C to 1260 °C.
• the step of descaling by water jetting of scale which is always performed during the existing process between the removal from the induction furnace and insertion into the extrusion press, is skipped.
• Skipping of the up to now necessary step of water jetting of scale is very significant because this is preventing cooling down by more than 80 *C, thus eliminating formation of temperature gradient and temperature fluctuations that are typical during the clearing of high-temperature-heating generated scale by means of high-pressure water jet descaling.
• the possibility of precise control of the blank 1 temperature is achieved by skipping the descaling.
• the blank1 and later the semi-product 5 created from it is upset and backward extruded in two steps. From this, during the first step, the blank 1 is placed at the bottom 6 of the extrusion press die 4 and here it is pressed by vertically moving ram ended with a piercing mandrel constituting the piercing tool 7.
• the blank 1 is moulded here by means of extrusion until a thick-walled hollow semi-product ⁇ having an inner cavity, walls, and bottom is moulded from it, as shown on Figs. 4 A. B.
• the coating 2 of material based on water glass is broken to pieces by pushing of the piercing tool 7 to the blank 1 and the semi-product 5 made of it, the coating 2 cracks off, and approximately ail this coating Z is removed during extrusion in the extrusion press.
• the water glass admixtures will make their way from the coating 2 into the surface layer of the semi-product 5 to the depth of maximum 10 ⁇ , these leftovers are removed later by blasting.
• the aforementioned extrusion takes place during continuation of the semi-product 5 temperature at 1100 to 1200 °C.
• the semi-product 5 is removed from the extrusion press, turned by 90'. and seated in this position into a horizontal drawing press, where the second step of forming in terms of backward drawing takes place.
• the semi-product 5 is put on a drawing mandrel having the diameter corresponding to the desired ftnai inner diameter of the produced cylinder, and in this drawing press, the semi-product ⁇ is extruded through a stripper ring and roller cartridges fitted with reduction rollers by means of which it is rolled on the mandrel. Rolling is performed so long until the semi-product 5 acquires the required outer and inner diameter.
• the final shape of the cylinder bottom is formed by insertion of the semi-product 5 bottom into a sizing die and subsequently, in the course of the backward movement of the drawing mandrel, the semi-product 5 is pulled off from the drawing mandrel with the help of stripping jaws, aftercooled, and subsequently necked by already known method by means of rotary forming or die forging process.
• the shape of the manufactured cylinder is finished in this way.
• Corrosion-resistant seamless pressure cylinders in the volume range from 5 litres up to 260 litres can be manufactured using the method according to the invention for any volume within the said range as single necked or double-necked cylinders.
• the invention allows pressing the semiproduct 5 wall even to the thickness of a thin-walled cylinder without loss of qualitative properties of the manufactured cylinder.
• the semi-product 5 wail is pressed even to the thickness of 2 to 21.5 mm,
• the cylinder wall thickness is selected in concrete terms within the above said range depending on the required cylinder volume, pressure for which the cylinder is designated, and requirements for qualitative properties and mechanical strength of the cylinder.
• FIG. 1 to 4 illustrate only the steps related directly to the new steps of the process of production of the cylinder according to the invention.
• the other steps and processes that are already known in this field and are described in the Background Art paragraph do not need to be illuminated using figures.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Extrusion Of Metal (AREA)
• Containers Having Bodies Formed In One Piece (AREA)
• Forging (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=55452969

Family Applications (1)

Country Status (7)

Families Citing this family (3)

Family Cites Families (11)

• 2015
  • 2015-12-03 CZ CZ2015-855A patent/CZ2015855A3/cs unknown
• 2016
  • 2016-01-08 ES ES16707614T patent/ES2731055T3/es active Active
  • 2016-01-08 RU RU2018123526A patent/RU2710484C1/ru active
  • 2016-01-08 WO PCT/CZ2016/050001 patent/WO2017092721A1/en active Application Filing
  • 2016-01-08 CN CN201680064469.9A patent/CN108348971B/zh active Active
  • 2016-01-08 EP EP16707614.0A patent/EP3365121B1/de active Active
  • 2016-01-08 US US15/768,750 patent/US20180304330A1/en not_active Abandoned

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