WO1996036961A2 - Pieces moulees en ceramique selectionnees et procede de selection de pieces moulees en ceramique exemptes de defauts - Google Patents

Pieces moulees en ceramique selectionnees et procede de selection de pieces moulees en ceramique exemptes de defauts Download PDF

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Publication number
WO1996036961A2
WO1996036961A2 PCT/EP1996/001900 EP9601900W WO9636961A2 WO 1996036961 A2 WO1996036961 A2 WO 1996036961A2 EP 9601900 W EP9601900 W EP 9601900W WO 9636961 A2 WO9636961 A2 WO 9636961A2
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WO
WIPO (PCT)
Prior art keywords
focus
spark
underwater
shock wave
focused
Prior art date
Application number
PCT/EP1996/001900
Other languages
German (de)
English (en)
Other versions
WO1996036961A3 (fr
Inventor
Hans-Andreas Lindner
Jürgen Hennicke
Original Assignee
Bayer Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bayer Aktiengesellschaft filed Critical Bayer Aktiengesellschaft
Publication of WO1996036961A2 publication Critical patent/WO1996036961A2/fr
Publication of WO1996036961A3 publication Critical patent/WO1996036961A3/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
    • B28B17/0063—Control arrangements
    • B28B17/0081—Process control
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/18—Methods or devices for transmitting, conducting or directing sound
    • G10K11/26—Sound-focusing or directing, e.g. scanning
    • G10K11/28—Sound-focusing or directing, e.g. scanning using reflection, e.g. parabolic reflectors
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K15/00—Acoustics not otherwise provided for
    • G10K15/04—Sound-producing devices
    • G10K15/06—Sound-producing devices using electric discharge

Definitions

  • Ceramic molded parts have a number of properties, such as temperature resistance, hardness, low density, low coefficient of thermal expansion, low thermal conductivity and corrosion resistance, etc., which they have for a large number of applications in the high temperature range, under temperature changes, even in a corrosive environment, etc predestine.
  • the high brittleness of molded ceramic parts is a disadvantage. Due to the high brittleness, even the smallest material defects, especially in the case of moving ceramic components, e.g. as components of internal combustion engines, for their destruction.
  • the technique of focused underwater shock waves has been developed especially for the area of kidney stone destruction and has been widely used.
  • One possibility for generating focused underwater shock waves is to bring about a plasma explosion in the focal point of a rotation ellipsoid by means of a discharging spark gap, the pressure wave of the plasma explosion taking the form of a
  • a focusing of the shock wave suitable for the proof test of ceramic components is still achieved with underwater spark gaps, with which an energy of 400 to 800 joules is released.
  • the half-value surface of the focus lies in the range from 3 to 5 cm 2 .
  • the half-value surface of the focus is to be understood as the closed area (approximately an ellipsoid) within which the pressure of the focused shock wave is greater than half the maximum pressure.
  • the present invention accordingly relates to a method for generating a focused underwater shock wave by means of underwater spark discharge in a focus of a hollow ellipsoid, characterized in that the total spark discharge energy is released by at least two simultaneous spark discharges in one focus each of a focusing ellipsoid, the at least two Ellipsoids have a common second focus.
  • At least three underwater spark discharges are preferably triggered simultaneously.
  • the number of spark discharges to be triggered at the same time can only be increased by the geometry, i.e. limited by the expansion of the focusing ellipsoids. According to the invention, it is not excluded to focus up to 12 shock waves in one focus. The achievable according to the invention
  • Maximum pressure in focus can be between 0.5 and 2.5 GPa.
  • the present invention also relates to a device for generating a focused underwater shock wave with high energy density, comprising at least two confocal partial ellipsoids, in the other focus of which a spark gap is provided, and means for generating simultaneous spark discharges in the
  • Part ellipsoids according to the invention are part-hollow rotational ellipsoids, the spark gap being in the focus within the part ellipsoid and the second focus outside the part ellipsoid. At least the partial ellipsoid should extend to a plane perpendicular to the major axis of the ellipsoid, which is twice the distance from the point of penetration of the major axis through the ellipsoid, like the focus. Due to the propagation behavior of the shock wave generated by the spark gap arranged parallel to and in the major axis of the ellipsoid, the energy bundling cannot generally be improved if the partial ellipsoid is larger than 1/2 ellipsoid.
  • Spark discharges are usually generated by a capacitor bank using a capacitor charging unit at voltages of 10 is charged up to 50 kilovolts, and the discharge is ignited via a switching spark gap by means of a trigger generator, which generates a voltage peak in the switching spark gap.
  • the means for generating simultaneous spark discharges can consist in the fact that the several spark gaps are connected in series.
  • Another means of generating simultaneous spark discharges is to trigger the trigger generators for the spark discharges at the same time.
  • Devices according to the invention are preferred which release a total energy of 1 to 5 kilojoules by means of underwater spark discharges, the half-value surface of the focus being less than 5 cm 2 , particularly preferably less than 3 cmr. This corresponds approximately to a focus diameter of 7 to 12 mm.
  • the half-value surface is the ellipsoidal surface enclosing the location of the pressure surge maximum, on which the mean pressure is half the pressure maximum.
  • the present invention also relates to a method for producing fault-free ceramic components by sintering green bodies, which is characterized in that each component is not subjected to a focused underwater shock wave which was generated by means of underwater spark discharge with an energy of 1 to 5 kilojoules before the sintering was carried out and wherein the half-value surface of the focus is less than 5 cm 2 , defective components being eliminated by destruction.
  • the invention further relates to a ceramic molded part selected by exposure to at least one focused underwater shock wave, the underwater shock waves using an underwater spark discharge of an energy of
  • the ceramic moldings are preferably after sintering and before
  • the ceramic components preferably have dimensions in at least one dimension of 5 to 30 mm. Shaped parts that have larger dimensions in at least two dimensions must be subjected to the focused shock wave several times at different points, since otherwise their freedom from errors cannot be guaranteed with certainty. In larger molded parts, the shock wave propagates with weakening, so that points further away from the impinging focus are no longer subjected to sufficient energy.
  • Partial ellipsoids are preferably used, the large elipsoid axis being between 15 and 25 cm and the axis ratio being 1.1 to 1.5, preferably up to 1.3.
  • the spark discharge energy in the range from 1 to 5 kJ is selected in
  • Suitable ceramic materials are Si 3 N 4 , A1N, BN, SiC, B 4 C, the transition metal carbides, nitrides, silicides, borides, the oxides Al 2 O 3 , ZrO 2 , SiO 2 , La-O 3 , Rare earth oxides, Cr 2 O 3 , TiO 2 , titanates, ferrites and any mixtures of these
  • Silicon nitride, aluminum oxide, zirconium oxide, silicon carbide and mixtures thereof are particularly preferred.
  • the molded parts selected according to the invention can initially be characterized as 100% error-free.
  • FIG. 1 shows a device according to the invention with which three underwater spark discharges are focused in a common focus.
  • FIG. 2 shows a horizontal section AA through the device according to FIG. 1.
  • Fig. 3 shows the principle of electrical spark discharge for the simultaneous triggering of two spark discharges.
  • FIG. 4 shows an alternative embodiment of the electrical circuit for simultaneously igniting two spark discharges.
  • FIG. 5 exemplifies the proof test for a valve stem made of silicon nitride.
  • FIG. 6 shows an example of an embodiment of the device according to the invention with 6 confocal spark discharges.
  • the device according to FIG. 1 consists of an upwardly open water tank 1 with a water surface 2 indicated, which in a corner has three circular openings 3 arranged at right angles to one another with respect to its longitudinal axis a and to which semi-ellipsoids 4 which are open from the outside of the container are flanged .
  • a spark gap (not shown) is arranged through an insertion opening provided on the back of the ellipsoid.
  • the second focus of each of the ellipsoids 4 is the common focus F c .
  • the ceramic molding to be tested is arranged in the focus with a surface such that the focused shock waves triggered at the same time can enter the molding as evenly as possible.
  • Fig. 2 shows a horizontal section AA through Fig. 1, which contains the two horizontal axes of the ellipsoids.
  • the spark gap 6 is additionally indicated in these ellipsoids.
  • Fig. 3 shows in principle the switching arrangement for generating the spark discharge.
  • a capacitor battery 10 is provided, which is charged by means of a capacitor charging unit via the charging resistor 12, for example to a voltage of 40 kV.
  • the trigger generator 13 generates a high-voltage pulse in the switching spark gap by means of an electrode 15, by means of which the switching spark gap is ionized, so that the total resistance in the circuit comprising the capacitor bank 10, the switching spark gap 14 and the two spark gaps 6 is reduced in this way that the spark gaps ignite.
  • the fact that the two spark gaps 6 are connected in series ensures that they ignite at the same time. 4, the two spark gaps 6a and 6b have separate identical supply and switching units as shown in FIG. 3.
  • the two trigger generators 13 are connected via a synchronization line 16.
  • valve stem 20 shows as a ceramic component a valve stem 20 with the valve plate 21 and the integrally formed axis 22.
  • the valve stem is arranged in the device according to FIG. 1 with suitable holding devices such that the common focus F c is in the region of the transition from the Valve plate to the valve axis is located.
  • the three arrows I, II and III indicate the relative arrangement of the large ellipse axes from FIG. 1.
  • FIG. 6 shows a device according to the invention with 6 spark gaps 6 arranged in a circular symmetry of the plane and the corresponding partial ellipsoids 4, which focus on the common focus F c .
  • a cylindrical shaped part 3 with an axis perpendicular to the plane of the drawing is shown as an example.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Automation & Control Theory (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

L'invention concerne un procédé et un dispositif permettant de produire des ondes de choc sous-marines focalisées, par décharge sous-marine multiple simultanée d'étincelles et par focalisation à l'aide d'ellipsoïdes à foyer commun. Selon ce procédé, une pression maximale de l'ordre du GPa est produite dans le foyer commun. L'invention concerne également l'utilisation dudit procédé comme test de vérification de pièces moulées en céramique. Les pièces moulées en céramique soumises au test de vérification sont au départ exemptes de défauts.
PCT/EP1996/001900 1995-05-19 1996-05-07 Pieces moulees en ceramique selectionnees et procede de selection de pieces moulees en ceramique exemptes de defauts WO1996036961A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19518408.4 1995-05-19
DE1995118408 DE19518408C2 (de) 1995-05-19 1995-05-19 Selektierte keramische Formteile und Verfahren zur Selektion fehlerfreier keramischer Formteile

Publications (2)

Publication Number Publication Date
WO1996036961A2 true WO1996036961A2 (fr) 1996-11-21
WO1996036961A3 WO1996036961A3 (fr) 1996-12-27

Family

ID=7762347

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1996/001900 WO1996036961A2 (fr) 1995-05-19 1996-05-07 Pieces moulees en ceramique selectionnees et procede de selection de pieces moulees en ceramique exemptes de defauts

Country Status (2)

Country Link
DE (1) DE19518408C2 (fr)
WO (1) WO1996036961A2 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4096738A (en) * 1976-03-25 1978-06-27 Bayer Aktiengesellschaft Method for testing filled glass containers
DE2718847A1 (de) * 1977-04-28 1978-11-02 Eberhard Prof Dr Rer Haeusler Vorrichtung zur zertruemmerung von nierensteinen mittels einer oder mehreren stosswellen
US4421200A (en) * 1981-12-16 1983-12-20 Ferralli Michael W Elliptically shaped transducer enclosure
EP0150843A2 (fr) * 1984-02-02 1985-08-07 COMPAGNIE GENERALE D'ELECTRICITE Société anonyme dite: Dispositif à ondes acoutiques focalisées pour étudier la structure d'un objet
EP0238772A1 (fr) * 1985-09-09 1987-09-30 Moshe Ein-Gal Dispositif pour désagréger des calculs dans le corps
US4734894A (en) * 1984-10-23 1988-03-29 Consiglio Nazionale Delle Ricerche Electroacoustic pulse source for high resolution seismic prospectings

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE375492C (de) * 1923-05-14 Siemens Schuckertwerke G M B H Einrichtung an Pendelhaemmern zur Festigkeitspruefung
DE2348063A1 (de) * 1973-09-25 1975-04-03 Eberhard Prof Dr Haeusler Vorrichtung zur beruehrungsfreien zerstoerung sproeder, in fluessige oder biologische medien eingebetteter einschluesse
DE2610061A1 (de) * 1976-03-11 1977-09-22 Johann Prof Dr I Kleinwaechter Reflektoren zur fokussierung einer drahtexplosionsstosswelle
DE3328068A1 (de) * 1983-08-03 1985-02-21 Siemens AG, 1000 Berlin und 8000 München Einrichtung zum beruehrungslosen zertruemmern von konkrementen
DE3524943A1 (de) * 1984-04-12 1987-01-15 Heye Hermann Fa Vorrichtung zum pruefen von glasbehaeltern
DE3527898C1 (de) * 1985-08-03 1987-03-12 Dornier System Gmbh Einrichtung zum Herausloesen von Mineralen aus dem sie umgebenden Material
DE3634046A1 (de) * 1986-10-06 1988-04-14 Siemens Ag Vorrichtung zum zertruemmern von konkrementen

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4096738A (en) * 1976-03-25 1978-06-27 Bayer Aktiengesellschaft Method for testing filled glass containers
DE2718847A1 (de) * 1977-04-28 1978-11-02 Eberhard Prof Dr Rer Haeusler Vorrichtung zur zertruemmerung von nierensteinen mittels einer oder mehreren stosswellen
US4421200A (en) * 1981-12-16 1983-12-20 Ferralli Michael W Elliptically shaped transducer enclosure
EP0150843A2 (fr) * 1984-02-02 1985-08-07 COMPAGNIE GENERALE D'ELECTRICITE Société anonyme dite: Dispositif à ondes acoutiques focalisées pour étudier la structure d'un objet
US4734894A (en) * 1984-10-23 1988-03-29 Consiglio Nazionale Delle Ricerche Electroacoustic pulse source for high resolution seismic prospectings
EP0238772A1 (fr) * 1985-09-09 1987-09-30 Moshe Ein-Gal Dispositif pour désagréger des calculs dans le corps

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
BIOMEDIZINISCHE TECHNIK, Bd. 34, Nr. 4, April 1989, Seiten 62-72, XP000008231 MULLER M: "DIE FOKUSSIERUNG VON WASSERSTOSSWELLEN ZUR LITHOTRIPSIE DURCH VERSCHIEDENE ELLIPSOIDREFLEKTOREN" *

Also Published As

Publication number Publication date
DE19518408C2 (de) 1998-07-02
WO1996036961A3 (fr) 1996-12-27
DE19518408A1 (de) 1996-11-21

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