Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/4505—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/04—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to gases
  • B05D3/0493—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to gases using vacuum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D31/00—Cutting-off surplus material, e.g. gates; Cleaning and working on castings
  • B22D31/002—Cleaning, working on castings
  • B22D31/005—Sealing or impregnating porous castings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
  • B22F3/26—Impregnating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L97/00—Compositions of lignin-containing materials
  • C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/02—Processes; Apparatus
  • B27K3/08—Impregnating by pressure, e.g. vacuum impregnation
  • B27K3/10—Apparatus
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/02—Processes; Apparatus
  • B27K3/15—Impregnating involving polymerisation including use of polymer-containing impregnating agents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers

Definitions

• the invention relates to the sealing of pores in porous rigid articles, particularly metal articles such as metal castings and sintered metal products but also materials such as wood or inorganic materials such as brick, stone, or concrete. It is however important that the pores in the material are not so big as to permit leaching out of the impregnant.
• the impregnant of the invention is used to impregnate materials such as paper and cloth.
• porosity can be divided into three types: through poro sity, blind porosity and enclosed porosity.
• Through porosity causes leakage and is the type with which founders are primarily concerned.
• Blind porosity having one entrance to the surface only, will not produce a leakage but can cause surface finishing problems through absorption of treatment fluids.
• Enclosed porosity causes no problems unless present in excess where it can cause structural failure.
• Other similar defects often encountered in the foundry include cold laps, cracks, blow holes, and inclusions ail of which are often referred to, incorrectly, as forms of porosity.
• examination of a casting rejected for leakage and marked by the inspector as porous reveals that it actually has a cold lap, crack or a blow hole.
• Cross linking of the linear polyester by styrene results in a hard, solvent resistant resin which completely fills the pores.
• a typical manufacturing process involves placing the cleaned, cold castings in an autoclave and subjecting them to a vacuum of not less than 12.7 mms of Hg for a minimum of 20 minutes. At this point the impregnant is admitted to the autoclave and brought to a level approximately two inches above the castings. Pressure of 90 to 100 lbs. per sq. in. is then applied to the autoclave for 30 minutes or more.
• the impregnant fluid is then returned to the storage tank to allow the removal of the castings and their transfer to the wash tank for the removal of the surface film left by the sealant.
• the parts are submerged in an oil for 45-60 minutes at 130°C or alternatively placed in a hot air recirculation oven for 11 ⁇ 2 hours.
• the final steps are to transfer the parts to a fresh water rinse to remove surface contamination.
• the present invention has been particularly developed for use with impregnants of the type described in U.K. Patent Specification No. 1547801 but is not limited thereto.
• Such impregnants cure thermally at a temperature of about 90°C and are thus conveniently cured by contacting the casting with hot water, either in the form of a bath or in the form of a spray.
• Impregnation processes previously used have been batch processes but these are not altogether convenient e.g. in the treatment of cylinder blocks for motor vehicles. It is however possible to treat metal castings individually. This generally necessitates blocking off of the casting and pressurising with impregnant from within, or drawing a vacuum and submerging the casting in the impregnant. Neither of these two ways is highly desirable because of the inherent problems of sealing up the openings in the casting.
• an article to be impregnated is placed on a base plate or other support member, a cover such as a cylinder is placed over it in sealing relation with the base plate (in the manner of a bell jar), vacuum (i.e. subatmospheric pressure) is applied to the upper part of the cylinder to remove air from the pores (e.g. for 30 seconds or more), impregnant is admitted (preferably through the base plate) under the action of the vacuum until it at least covers the pores, the vacuum is broken, excess impregnant is removed from the cover (preferably by gravity drainage), and the cover is removed from the base plate.
• the casting may then be removed from the base plate and placed on a conveyor for further treatment e.g. a cold water wash and a not water spray in the case of the impregnant described in Specification No. 1547801.
• cleaning and/or curing is effected within one or more further treatment chambers formed by a cover engaging a support for the article.
• Conveyor means are provided to move the article from one support to the next or the support can be formed, at least in part, by a portion of the conveyor as described in the above-mentioned U.K. Patent Application.
• curing of impregnant in the pores is effected by contact with gas (preferably air) at a temperature in the range 60-130°C.
• gas preferably air
• this not only effects a very rapid cure but "burns off" unwanted impregnant from the surface of the casting before it has a chance to cure. This means that a preliminary thorough cleaning and washing step is not required. If draining is insufficient, or insufficiently rapid, impregnant can be removed by mechanical means such as centrifuging or a gas blast- In other words, after impregnation, the whole treatment can be "dry".
• the hot air may be static but is preferably blown onto the article; this may be done in a tunnel (e.g. with the air current transverse to the direction of movement) or in a static oven. It is desirable that the article is rotated during the hot air treatment.
• Fig. 1 is a side elevation of apparatus according to the invention
• Fig. 2 is an end elevation of the apparatus of Fig. 1,
• Fig. 3 is similar to Fig. 2 but shows a modification for simultaneously treating two articles.
• Fig. 4 is a section through a modified curing station.
• the apparatus comprises a frame 1 having a gantry 2 which supports three air cylinders 4, 5, 6.
• the respective rods of these cylinders carry bell jar covers 10, 1 1, 12 for movement between an upper position shown in full lines and a lower position shown in ghost lines. In their lower positions, the covers 10, 11, 12 cooperate with supports 14 , 15, 16 to provide first, second and third treatment chambers (from right to left in Fig. 1).
• the first treatment chamber is an impregnation chamber and it operates in substantially the same manner as the impregnation chamber described in Figs. 1 - 3 of our above-mentioned U.K. application.
• the cover 10 makes sealing contact with the support 14, a vacuum is drawn through line 18 and impregnant is admitted through the support 14, preferably by releasing vacuum in a simultaneously evacuated impregnant reservoir. After impregnation the vacuum is released in the treatment chamber and impregnant drains back through the support 14.
• the second treatment chamber has a support 15 with an inner area which is rotatable (not shown). This permits the article to be cleaned by centrifuging off impregnant still on its surface.
• the cover 11 has an axial rotary cap (not shown) inside it for engaging the top of the article and keeping it on the turntable provided by the inner area of the support.
• Air jets 20 (three are shown in Fig. 1) are arranged to direct cold air on to the article and blow off excess impregnant. It is however possible to effect cleaning by centrifuging alone or air jets alone. Alternatively it is possible to use a conventional cold water wash with or without jets.
• the third treatment chamber as shown in Fig. 1, has a pipe 22 for supplying hot water to the cover 12, the water passing out through the support 16 after use and being recycled. Hot air or steam can also be used.
• the transfer system comprises a fixed rail 25 secured to the frame 1 and running the full, length thereof.
• the rail 25 has four rollers 26 on which are mounted a movable rail 27 which can be shuttled to and fro by a bracket 28 attached to the rod of a pneumatic cylinder (not shown).
• On the rail 27 is mounted a carrier rail 29 which carries four spaced arms 30.
• each arm 30 has a gripper means 31.
• the article is a carburettor with an opening at the top and the gripper means 31 comprises an air cylinder which is arranged to expand a rubber ring within the opening.
• Two parallel links 32 are used to mount the carrier rail 28 on the rail 27 at each end and a further air cylinder 3* is used to raise and' lower it.
• the four arms 30 thus move up and down at the same time.
• the arms 30 and their gripper means 31 can move articles forward and deposit them on the supports.
• the arms then move to a position between the covers which are then lowered. After the treatments have been completed the arms 30 reengage the articles and move them forwards again.
• each arm 30 has two gripper means 31 for simultaneously transferring two articles in side-by-side relation.
• the support 14 comprises a grille 35 beneath which is disposed a fan 36 having a motor 37 which can rotate it about a vertical axis.
• a sleeve 38 is mounted within the cover 10 by radial arms (not shown) and contains the porous article.
• Black heater elements 39 are disposed in the annular space 41 so formed and in practice air is forced by the fan 36 upwards through the space 41 and down over the article for recirculation. Such recirculation is economical and serves to burn any gases and vapours given off by the article 20 so avoiding air pollution problems.
• the cover 10 is of thin stainless steel. In operation, the transfer system lifts the articles from one conveyor and places them on another conveyor after treatment. It has been found in practice that the total cycle time can often be reduced to about one minute.
• the article is cleaned in the second chamber with an organic solvent and the impregnant recovered therefrom. Any solvent remaining on the article in the third chamber is evaporated.
• a final cure can be effected by placing the articles leaving the apparatus in a muffler oven.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Structural Engineering (AREA)
• Wood Science & Technology (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Coating Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10520315

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (8)

Family Cites Families (5)

• 1982
  • 1982-03-10 GB GB8206974A patent/GB2094674A/en not_active Withdrawn
  • 1982-03-11 JP JP57500842A patent/JPS58500240A/ja active Pending
  • 1982-03-11 IT IT20107/82A patent/IT1150274B/it active
  • 1982-03-11 WO PCT/GB1982/000083 patent/WO1982003030A1/en not_active Application Discontinuation
  • 1982-03-11 AU AU81500/82A patent/AU8150082A/en not_active Abandoned
  • 1982-03-11 EP EP82900653A patent/EP0073783A1/de not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events