WO2006075211A2 - Dispositif de dosage pour appareil de projection de particules - Google Patents

Dispositif de dosage pour appareil de projection de particules Download PDF

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Publication number
WO2006075211A2
WO2006075211A2 PCT/IB2005/003977 IB2005003977W WO2006075211A2 WO 2006075211 A2 WO2006075211 A2 WO 2006075211A2 IB 2005003977 W IB2005003977 W IB 2005003977W WO 2006075211 A2 WO2006075211 A2 WO 2006075211A2
Authority
WO
WIPO (PCT)
Prior art keywords
conduit
particulate material
screw
turbulence chamber
delivery conduit
Prior art date
Application number
PCT/IB2005/003977
Other languages
English (en)
Other versions
WO2006075211A3 (fr
Inventor
Pierre Rochat
Original Assignee
Exa Sa
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 Exa Sa filed Critical Exa Sa
Publication of WO2006075211A2 publication Critical patent/WO2006075211A2/fr
Publication of WO2006075211A3 publication Critical patent/WO2006075211A3/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
    • B24C7/0046—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier
    • B24C7/0069—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier with means for preventing clogging of the equipment or for preventing abrasive entering the airway

Definitions

  • the invention relates to a dosing device for controlled delivery of a particulate material .
  • the invention relates to a particle blasting apparatus which includes a dosing device for controlled delivery of particulate material to a blasting nozzle .
  • a high volume of air is required to mix with the aggregate in the tank and may stay in contact with the aggregate for a long period or time .
  • the types of aggregate used in blasting operations have a tendency to be sensitive to humidity, the particles of the aggregate tend to bind together, blocking up the adjustable (or non adjustable) metering device .
  • This problem is further complicated by the difficulties involved in providing dry air for pressurising the system, these difficulties including the size and expense of a dryer which is capable of drying the volumes of air involved
  • a dosing device for controlled delivery of a particulate material comprising:
  • - a particulate material container - a particulate material metering device; - a feed conduit adapted to deliver particulate material from the container to the metering device; and - a particulate material delivery conduit adapted to receive metered particulate material from the metering device,
  • feed conduit comprises means for providing a tortuous flow path for the particulate material through the conduit .
  • the means for providing a tortuous flow path comprises a screw, wherein the particulate material flows down the screw in a helical manner along the threads of the screw.
  • the flow path is slanted.
  • the screw and the feed conduit are separate, wherein the screw is dimensioned such that the conduit snugly embraces the screw.
  • the screw and conduit may be integrally formed, or the same effect could be obtained by providing a helical bore arrangement within a solid body. It is important to note that the screw is not adapted to turn within the conduit, rather it remains static and the particulate material flows along the threads in a helical manner under the force of gravity and/or the force of pressure from the pressurised particulate material container .
  • the rate of flow of product along the screw may be varied by using screws of different dimensions , i . e . different pitch of threads , depth of threads , number of turns , etc .
  • the screw is dimensioned to deliver particulate material to the metering device at a desired rate. While any given screw will have a fixed flow rate, the use of a removable screw allows different screws to be used in different application, and in this regard screws may be chosen that provide a fixed maximum flow rates of anything in the range of less than 1 and greater than 100kg/hour (wt/wt) . A preferred maximum flow rate for general blasting operations is about 25 kg/hour . When the dosing device is used for microblasting, i . e . dental application, the screw will be dimensioned to provide a fixed maximum flow rate of anything between 100 and 1000g/hour .
  • the metering device comprises a valve which is adjustable to vary the rate of flow of the particulate material into the delivery conduit .
  • the screw is chosen to provide a maximum flow of 25 kg/hour (wt/wt)
  • the metering device is adjustable to vary to rate of flow of product into the delivery conduit over the range 0 to 25 kg/hour .
  • the delivery conduit comprises a turbulence chamber adapted to receive particulate material from the metering device, and means for generating a depression within the turbulence chamber .
  • the depression within the turbulence chamber is generated by a three-part system comprising the turbulence chamber, a nozzle of narrow bore located upstream of the turbulence chamber, and adapted to deliver pressurised air into the turbulence chamber, and a conduit for receiving a mixture of pressurised air and particulate material, the conduit having a bore larger than that of the nozzle .
  • the depression generating means is adapted to generate a depression within the turbulence chamber of between -0.5 to -1.0 Bar, ideally about -0.7 Bar .
  • the generation of a depression within the turbulence chamber has the effect of mixing the air and the particulate material , and also accelerates the thus-formed mixture of air and particulate material downstream along the delivery conduit .
  • the dosing device further includes a main air flow conduit which is adapted to introduce pressurised air into the delivery conduit downstream of the turbulence chamber .
  • the purpose of the main air flow conduit is to further accelerate the mixture of air and particulate material downstream along the delivery conduit .
  • the invention also relates to a particle blasting apparatus comprising a dosing device according to the invention, a source of compressed air, and a blasting nozzle in fluid communication with the delivery conduit .
  • the invention also relates to a method of operating a particle blasting apparatus according to the invention, comprising the steps of :
  • the means for providing a tortuous path is provided by a screw.
  • the pressurised air provided to the delivery conduit is such as to generate a depression in a turbulence chamber of the delivery conduit of between -0.5 and -1.0 Bar, ideally about -0.7 Bar .
  • the method involves the introduction of pressurised air from a main air conduit into the delivery conduit downstream of the turbulence chamber, and wherein the pressure and volume of air applied in the product material container is less than the pressure and volume of air in the main air flow conduit .
  • the pressure at the depression added to the pressure in the particulate material container is greater than the pressure in the main air flow conduit .
  • the invention in a second aspect, relates to a dosing device for controlled delivery of a particulate material comprising: - a particulate material container; - a particulate material metering device; - a feed conduit adapted to deliver particulate material from the container to the metering device; and - a particulate material delivery conduit adapted to receive metered particulate material from the metering device,
  • the delivery conduit comprises a turbulence chamber adapted to receive particulate material from the metering device, and means for generating a depression within the turbulence chamber
  • the device includes a main air flow conduit which is adapted to introduce pressurised air into the delivery conduit downstream of the turbulence chamber.
  • the depression within the turbulence chamber is generated by three-part system comprising the turbulence chamber, a nozzle of narrow bore located upstream of the turbulence chamber, and adapted to deliver pressurised air into the turbulence chamber, and a receiving conduit for receiving a mixture of pressurised air and particulate material , the receiving conduit having a larger bore than the nozzle .
  • the depression generating means is adapted to generate a depression of between -0.5 to -1.0 Bar, typically between -0.7 and -0.9 Bar.
  • the feed conduit comprises means for providing a tortuous flow path for the particulate material through the conduit .
  • the means for providing a tortuous flow path comprises a screw, wherein the particulate material flows down the screw in a helical manner along the threads of the screw.
  • the screw and the feed conduit are separate, wherein the screw is dimensioned such that the feed conduit snugly embraces the screw.
  • the screw is dimensioned to deliver particulate material to the metering device at a rate of about 25 kg/hour (wt/wt) .
  • the metering device comprises a valve which is adjustable to vary the rate of flow of the particulate material into the delivery conduit .
  • the invention also relates to a particle blasting apparatus comprising a dosing device according to the invention, a source of compressed air, and a blasting nozzle in fluid communication with the delivery conduit .
  • the invention also relates to a method of operating a particle blasting apparatus according to the second aspect of the invention, comprising the steps of : - adjusting the metering device to achieve the desired rate of delivery of particulate material into the delivery conduit ; - pressurising the product material container; and - providing pressurised air to the delivery conduit upstream of the turbulence chamber such that a depression is created in the turbulence chamber and mixture of air and particulate product is accelerated along the delivery conduit ; and - providing pressurised air to the main air flow conduit which further accelerates the mixture of air and particulate product along the delivery conduit towards the blasting nozzle,
  • the pressurised air provided to the delivery conduit is such as to generate a depression in a turbulence chamber of the delivery conduit of between -0.5 and -1.0 Bar, ideally about -0.7 Bar .
  • the pressure in the particulate material container (Pl ) added to the pressure (depression) in the turbulence chamber is greater than the pressure in the main air flow conduit (P4 ) .
  • Fig . 1 is an elevational , partly cut-away, view of a dosing device according to the invention
  • Fig. 2 is a side elevational , partly cut-away, view of the dosing device of Fig. 1 showing a screw and valve in position;
  • Fig. 3 is an elevational, partly cut-away, view of a dosing device according to an alternative embodiment of the invention.
  • Fig . 4 is an elevational , partly cut-away, view of the dosing device of Fig. 3 showing a screw and valve in position.
  • the dosing device comprises a feed conduit 1 formed in a dosing device body 2 which provides fluid communication between a particulate material container (not shown) and a metering device 6 , 7.
  • the metering device 6 , 7 functions to meter the flow of particulate material from the feed conduit 1 to a delivery conduit below the metering device .
  • the feed conduit 1 includes a screw 8 which fits snugly within the conduit 1.
  • the dimensions of the screw are chosen to provide a maximum flow rate in a helical manner along the threads of the screw of about 25 kg/hour .
  • the metering device comprises a cylindrical socket 7 having input aperture 7.1 and a diametrically opposed larger output aperture 7.2.
  • a valve (or tap) 6 comprises a cylindrical plug which is dimensioned to fit within the socket 7 in a tight but sliding manner .
  • the valve 6 includes a through hole (not shown) which when aligned with the input and output apertures allows particulate material to pass into the delivery conduit below. Adjustment of the valve 6 by rotation allows the flow rate through the valve to be varied in the range 5 to 25 kg/hour (wt/wt) , or even fully prevented.
  • the delivery conduit includes a turbulence chamber 5 located directly below and adjacent the output aperture 7.2 of the metering device, and a venturi system consisting of a pressurised air delivery conduit 3 , and a receiving conduit 4 for receiving a mixture of pressurised air and particulate material from the turbulence chamber 5.
  • the pressurised air delivery conduit 3 has a nozzle 3a of narrow bore (about 2mm) located adjacent the turbulence chamber 5.
  • the receiving conduit 4 has a bore of about 5mm.
  • Figs 2 to 4 there is illustrated a further embodiment of the invention in which parts similar to those illustrated with reference to Figs 1 and 2 are assigned the same reference numerals .
  • the downstream elements of the delivery conduit are illustrated.
  • the main air flow conduit 10 provides pressurised air (P4 ) into the delivery conduit downstream of the turbulence chamber 5.
  • the downstream part of the delivery conduit widens to a bore of about 20mm, which is the same bore as that of the main air flow conduit 10.
  • the bore of the delivery conduit remains at about 20mm until it reaches the nozzle .
  • the particulate material container (not shown) is pressurised (Pl ) to a pressure of about 1 Bar .
  • Material in the container flows through the conduit along the threads of the screw 1 is a helical manner.
  • the dimensions of the screw 1 are chosen such that the maximum flow rate along the screw is about 25 kg/hour .
  • Adjustment of the metering device 6 , 7 allows the ultimate flow rate into the turbulence chamber to be accurately varied to between 0 and 25 kg/hour .
  • the working pressure is defined by setting the pressure in the main air flow conduit (P4 ) .
  • the pressure (P2 ) in the pressurised air delivery conduit 3 is set such that a depression (Dep) of about -0.7 Bar is achieved in the turbulence chamber 5.
  • a pressure (P2 ) of between 2 and 4 Bar is sufficient to achieve such a depression.
  • This results in a cumulative pressure in the receiving conduit (Pl + Dep P3 ) of about 1.7 Bar .
  • the pressure at P3 needs to be greater than the pressure in the main air flow conduit P4. Given that P3 is about 1.7 Bar, a working pressure of about 1.5 may be chosen for P4.
  • the pressure in main air flow conduit, P4 (which is approximately equal to the working pressure) must always be less than the pressure in the particulate material container (Pl ) added to the depression in the turbulence chamber (Dep) , i . e . :
  • the depression will be set at a pressure of between -0.5 and -1.0 Bar, usually about -0.7 Bar, and generally will not be varied.
  • the pressures Pl and P4 may be varied to achieve the desired working pressure . If the pressure P4 needs to be changed, the pressure Pl will automatically be changed in a proportional manner, ensuring that the formula P4 ⁇ [Pl + Dep] is adhered to .
  • the generation of a depression in the turbulence chamber helps mix the particulate material with the air, and also assists in the acceleration of the mixture of product and air into the downstream parts of the delivery conduit towards the main air flow.
  • the depression effect created in the turbulence chamber also prevents the generation of any back-pressure in the turbulence chamber, and allows both the pressure, and volume, of air supplied to the particulate material container be minimised. This has the direct effect of minimising the amount of agglomeration or "caking" which occurs in the feed conduit and 1 and metering device 6 , 7.
  • the invention also has a significant effect on the volumes of air used.
  • the pressure required in the particulate material container was greater, thus the volumes of air required were greater ( typically about 60% to 70% of total air came from the pressurised product container .
  • the "push" required from the particulate material container is considerably less , thus less pressure and less air are required.
  • the amount of air required in the product container is only about 20% to 40% of the total air . This means that less moisture is in contact with the particulate material , which results in less agglomeration and caking of the particulate material .

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Nozzles (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

Abstract

L'invention concerne un dispositif de dosage pour la libération régulée de matière particulaire, comprenant un récipient à matière particulaire, un dispositif de dosage de la matière particulaire, un conduit d'amenée conçu pour envoyer de la matière particulaire du récipient au dispositif de dosage, et un conduit de libération de matière particulaire conçu pour recevoir la matière particulaire dosée provenant du dispositif de dosage, le conduit d'amenée comprenant des moyens de formation d'un trajet d'écoulement tortueux pour la matière particulaire dans le conduit. Des procédés de libération régulée d'une matière particulaire et un appareil comportant ledit dispositif de dosage sont également décrits.
PCT/IB2005/003977 2005-01-14 2005-12-12 Dispositif de dosage pour appareil de projection de particules WO2006075211A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0500649A GB0500649D0 (en) 2005-01-14 2005-01-14 Dosing device for a particle blasting apparatus
GB0500649.9 2005-01-14

Publications (2)

Publication Number Publication Date
WO2006075211A2 true WO2006075211A2 (fr) 2006-07-20
WO2006075211A3 WO2006075211A3 (fr) 2006-10-19

Family

ID=34224537

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2005/003977 WO2006075211A2 (fr) 2005-01-14 2005-12-12 Dispositif de dosage pour appareil de projection de particules

Country Status (2)

Country Link
GB (1) GB0500649D0 (fr)
WO (1) WO2006075211A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2911082A1 (fr) * 2007-01-10 2008-07-11 Richard Bodin Procede de decapage ou de nettoyage utilisant des particules abrasives a base de coquillages broyes
WO2013009320A1 (fr) * 2011-07-14 2013-01-17 Bell Helicopter Textron Inc. Régulation d'humidité pour systèmes de projection abrasive

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB191122668A (en) * 1911-10-14 1912-05-16 Ludwig Sauer Improved Sand Blast Apparatus.
US4631871A (en) * 1982-04-19 1986-12-30 Fluid Engineering Products Limited Abrasive fluid jet apparatus
US4735021A (en) * 1986-05-12 1988-04-05 A.L.C. Co., Inc. Abrasive blasting system
WO1997049525A1 (fr) * 1996-06-27 1997-12-31 Wizard Technology Limited Dispositif de projection abrasive

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB191122668A (en) * 1911-10-14 1912-05-16 Ludwig Sauer Improved Sand Blast Apparatus.
US4631871A (en) * 1982-04-19 1986-12-30 Fluid Engineering Products Limited Abrasive fluid jet apparatus
US4735021A (en) * 1986-05-12 1988-04-05 A.L.C. Co., Inc. Abrasive blasting system
WO1997049525A1 (fr) * 1996-06-27 1997-12-31 Wizard Technology Limited Dispositif de projection abrasive

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2911082A1 (fr) * 2007-01-10 2008-07-11 Richard Bodin Procede de decapage ou de nettoyage utilisant des particules abrasives a base de coquillages broyes
WO2013009320A1 (fr) * 2011-07-14 2013-01-17 Bell Helicopter Textron Inc. Régulation d'humidité pour systèmes de projection abrasive
US9168635B2 (en) 2011-07-14 2015-10-27 Textron Innovations Inc. Humidity control for abrasive blasting systems

Also Published As

Publication number Publication date
WO2006075211A3 (fr) 2006-10-19
GB0500649D0 (en) 2005-02-23

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