US3822988A - Manufacture of hollow clayware articles - Google Patents

Manufacture of hollow clayware articles Download PDF

Info

Publication number
US3822988A
US3822988A US00369881A US36988173A US3822988A US 3822988 A US3822988 A US 3822988A US 00369881 A US00369881 A US 00369881A US 36988173 A US36988173 A US 36988173A US 3822988 A US3822988 A US 3822988A
Authority
US
United States
Prior art keywords
mandrel
article
clay
firing
pipe
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US00369881A
Other languages
English (en)
Inventor
J Booth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hepworth Iron Co Ltd
Original Assignee
Hepworth Iron Co Ltd
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 Hepworth Iron Co Ltd filed Critical Hepworth Iron Co Ltd
Application granted granted Critical
Publication of US3822988A publication Critical patent/US3822988A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • B28B21/00—Methods or machines specially adapted for the production of tubular articles
    • B28B21/92—Methods or apparatus for treating or reshaping

Definitions

  • the method may include the step of drying the article to a predetermined hardness before firing.
  • the mandrel may be fitted in the article at any stage before the clay becomes plastic, but is preferably fitted after drying the moulded article.
  • the insertion and removal of the mandrel, referred to as mandrel cycling, may take place entirely within the firing kiln.
  • the relative sizes of the mandrel and the article should be such that when the clay becomes plastic during the firing step, it shrinks onto the mandrel, thereby closely conforming to the mandrel. Contrary to expectations, the clay is not prone to cracking in spite of conforming closely to the mandrel whilst it is in the plastic condition. Immediately, when there is a drop in temperature, the differential shrinkage causes the mandrel to separate from the article.
  • the method may further include the step of freezecooling the article, after it has been fired, by blowing air into the firing kiln.
  • the accuracy of sizing is dependent, naturally, on the accuracy of the mandrels.
  • These may be formed of high heat resistant material, e.g., refractory metals, or heat resistant alloys such as those in the Nimonic (Registered Trade Mark) range, which, even after considerable repeated use, accurately maintain their dimensions and shape.
  • Mandrel materials which can be used to advantage are heat-resisting steels characterised by highresistance to oxidation or scaling and the maintenance of dimensions under stress at elevated temperatures and through thermal cycling.
  • the scaling, or oxidation-resistance, of heat-resisting steels is due primarily to the element chromium and, to a lesser extent, to silicon.
  • the chromium in this class of steels ranges from approximately 8% to whilst silicon may be present in additions up to 4%.
  • the advantage of nickel, from the point of view of oxidation resistance, is only apparent when the nickel content is high, i.e. when the iron is largely replaced by the nickel.
  • Chromium confers good scaling resistance but does not contribute to creep resistance.
  • the most useful element is the. nickel which, when added to a chromium steel in sufficient quantities, makes the steel austenitic in bait and tungsten.
  • a particularly successful heat-resisting steel has been found to be an iron/chromium ferritic alloy containing about 28% chromium.
  • This particular type of alloy was selected as being especially suitable for resisting kiln conditions of temperatures up to l,l00 C in an atmosphere where clayware items are being fired, where high sulphur and oxidation is prevalent and where strength, although not of primary importance, must be given consideration.
  • Another advantage with this material is that it is magnetic and this property can be utilised in the insertion of blanks into the clay.
  • the material also has cost advantages, being cheaper than the high nickel content steels.
  • the method is particularly suited for the sizing of clayware pipes.
  • the method may include the step of inserting a mandrel internally of each end of the pipe for accurately detemiining the dimensions of the ends .of the pipe when fired, the process also having the effect of indirectly determining the external dimensions of the pipe ends. This permits the manufacture of pipes to close tolerances, which is desirable particularly in the cases of pipes of the spigot and socket coupling type where close fitting couplings are advantageous.
  • a spigoted and socketed pipe moulded from clay is stood on its spigoted end over a mandrel supported by a setting ring having a larger outer diameterso as to support the pipe also, and a mandrel is placed in the socketed end.
  • a plain-end (i.e., nonsocketed) pipe may be stood on either end over a mandrel supported by a setting ring having a larger outer diameter so as to support the pipe also, and a mandrel inserted in the upper end with a flange'to rest on the upper end face so as to support that mandrel.
  • both mandrels may be provided with flanges so that either can be used at either end, and both mandrels (and also a mandrel for the spigoted end of a spigoted and socketed pipe) may be provided with a slight taper the larger end of which is adjacent the flange, to facilitate insertion in pipe ends or setting of pipe ends over the mandrels.
  • FIG. 1 shows a sectional side view of a clay pipe supported on a kiln car before firing and with a mandrel fitted in each of its ends;
  • FIG. 2 is a schematic representation of the expansion and contraction curves of the pipe and the mandrels through the firing and cooling stages.
  • FIG. 1 there is shown a clayware pipe 10 having a spigot end 12 and a socket end 14.
  • the pipe 10 is supported upright with the spigot end 12 downwards on a kiln car 16 (only partially shown) by means of a setting ring 18.
  • a spigot mandrel 20 is fitted with clearance in the spigot end 12 of the pipe 10 by supporting it on a second setting ring 21 which is also supported on the kiln car 16.
  • a socket mandrel 22 is fitted with clearance in the socket end 14, the socket end 14 being slightly wider than the body portion of the pipe, thereby forming an internal shoulder 24 which supports the socket mandrel 22.
  • the pipe After moulding or extrusion of the pipe and either before or after mandrel insertion the pipe is dried at a temperature of up to 200 C until the moisture content has been reduced to approximately 1%.
  • the drying process may be carried out in separate drying chambers or on a roller drier conveyor.
  • the pipes may be set directly on the kiln car after extrusion and the car then taken through a drying kiln. The latter method reduces the number of handling operations.
  • Another variation would be first to dry the pipes to an intermediate degree of dryness and then to place them on the kiln car for further drying.
  • the pipe is then placed on the kiln car 16 with the mandrels 20 and 22 in position as shown in FIG. 1.
  • the inside diameters of the pipe ends 12 and 14 are slightly larger than the outside diameters of the mandrels.
  • the mandrels 20 and 22 are made from steel having a high resistance to oxidation or scaling, and which is able to maintain its shape under stress at elevated temperatures and through thermal cycling.
  • a steel found to be particularly suitable was an iron/chromium ferritic alloy having the following composition:
  • This alloy has the additional advantage that it is magnetic, which property may be advantageously utilized in inserting the mandrels into or withdrawing the mandrels from the pipe.
  • the car After the pipe has been placed on the kiln car 16, the car is moved into a firing kiln and the temperature raised to approximately l,040 C to fire the clay.
  • the ppes are freezecooled by blowing air into the kiln (in known manner) whereby their temperature is reduced to approximately 700 C in a period of 4 hours.
  • the mandrels will have contracted more than the pipe and will, at this stage, have separated from the pipe.
  • the mandrels are then removed from the pipe.
  • the chain dotted line 30.1 indicates the expansion curve of one of the mandrels as the firing process proceeds from left to right in the graph. The expansion continues until the maximum temperature 32 is reached and thereafter contracts along chain dotted line 30.2 as the pipe is freezccooled.
  • the solid line 34.1 indicated the expansion of the pipe as it is heated during the first part of the firing process.
  • the initial clearance between the pipe and the mandrel is sufficient to prevent the mandrel from expanding to a larger diameter than that of the pipe during this first part.
  • the clay starts to fuse, causing the pipe to contract along the solid line 34.2.
  • Contraction of the clay begins with the breakdown of the micaceous clay mineral and the liberation of glass forming and fluxing oxides.
  • the clay continues to contract until it has shrunk into contact with the mandrel.
  • fusing commences, the clay becomes plastic and is therefore plastically deformed to a shape corresponding closely with that of the mandrel. Thereafter the clay is forced to expand slightly together with the mandrel along the solid line 34.3 until the maximum temperature 32 is reached.
  • the dotted lines 34.5 and 34.6 indicate the contraction of the pipe which would occur if the mandrel were not present.
  • Socket size Spigot size (ins.) (ins) Design size 10.926 (l.D.) 10.460 (O.D.) Mandrel size,
  • the pipes were fired at a maximum temperature of 1,040 C 1 10 C and a circularity with a tolerance of 0.030 inch in the final product was obtained.
  • a method of sizing a clayware article comprising internally fitting the article before firing with amandrel having a clearance therefrom sufficientto prevent the mandrel from expanding to a larger outer diameter than the internal diameter of the article where the mandrel is fitted until the article becomes plastic during firing, the mandrel having a coefficient of expansion greater than the coefficient of expansion of the clay when fired, firing the article to a temperature at which the clay becomes plastic and conforms to the mandrel, allowing the fired article to cool whereby the mandrel becomes separated from the article by virtue of the differential shrinkage of the fired clay and the material of the mandrel, and removing the mandrel from the article.
  • mandrel is formed from a steel including between 8 to 30% chromium.
  • mandrel is made from an iron/chromium ferritic alloy containing about 28% chromium.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
  • Devices For Post-Treatments, Processing, Supply, Discharge, And Other Processes (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)
  • Rigid Pipes And Flexible Pipes (AREA)
  • Porous Artificial Stone Or Porous Ceramic Products (AREA)
US00369881A 1972-06-15 1973-06-14 Manufacture of hollow clayware articles Expired - Lifetime US3822988A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2809172A GB1390965A (en) 1972-06-15 1972-06-15 Manufacture of hollow clayware articles

Publications (1)

Publication Number Publication Date
US3822988A true US3822988A (en) 1974-07-09

Family

ID=10270121

Family Applications (1)

Application Number Title Priority Date Filing Date
US00369881A Expired - Lifetime US3822988A (en) 1972-06-15 1973-06-14 Manufacture of hollow clayware articles

Country Status (14)

Country Link
US (1) US3822988A (es)
AU (1) AU471115B2 (es)
BE (1) BE800863A (es)
CA (1) CA1000937A (es)
CS (1) CS166844B2 (es)
DD (1) DD104458A5 (es)
DE (1) DE2330620C2 (es)
ES (1) ES415970A1 (es)
FR (1) FR2190048A5 (es)
GB (1) GB1390965A (es)
IE (1) IE38059B1 (es)
IT (1) IT986525B (es)
NL (1) NL172628C (es)
ZA (1) ZA733998B (es)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4770631A (en) * 1986-07-25 1988-09-13 Didier-Werke Ag Apparatus and brick member for supporting a ceramic tube during firing thereof

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1086166B (de) * 1958-09-26 1960-07-28 Hermann Muecher Vorrichtung zum lotrechten Aufeinanderstellen von Muffenrohren aus zu brennenden Werkstoffen waehrend des Brennens

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4770631A (en) * 1986-07-25 1988-09-13 Didier-Werke Ag Apparatus and brick member for supporting a ceramic tube during firing thereof

Also Published As

Publication number Publication date
CS166844B2 (es) 1976-03-29
NL172628C (nl) 1983-10-03
CA1000937A (en) 1976-12-07
DE2330620A1 (de) 1974-01-03
NL172628B (nl) 1983-05-02
FR2190048A5 (es) 1974-01-25
GB1390965A (en) 1975-04-16
ZA733998B (en) 1974-05-29
IE38059B1 (en) 1977-12-21
IE38059L (en) 1973-12-15
NL7308391A (es) 1973-12-18
DD104458A5 (de) 1974-03-12
DE2330620C2 (de) 1982-09-30
AU5684773A (en) 1974-12-12
IT986525B (it) 1975-01-30
AU471115B2 (en) 1976-04-08
ES415970A1 (es) 1976-05-16
BE800863A (fr) 1973-10-01

Similar Documents

Publication Publication Date Title
US4117062A (en) Method for making a plastic container adapted to be grasped by steel drum chime-handling devices
DK153300B (da) Fremgangsmaade til fremstilling af et hullegeme af plastmateriale
US1923148A (en) Method and means of fabricating tubing of vitreous material
SU1749267A1 (ru) Способ изготовлени гофрированного стального пластыр
CN103056180B (zh) 一种薄壁23000mm超长管热挤压工艺
US3822988A (en) Manufacture of hollow clayware articles
US3383900A (en) Method of sizing of metal objects
US1296842A (en) Method of making cartridge-cases.
US4586944A (en) Method of manufacturing hollow glass objects, and apparatus for carrying out the method
US4157111A (en) Method of heat-treating ductile cast iron pipe
KR19980018521A (ko) 냉간가공된 분말금속에 의한 단조품 형성방법
JPH03104805A (ja) 複合管の製造方法
CA2258437A1 (en) Method and apparatus for expanding and conferring a cup shape to the terminal junction segment of bi-axially oriented pipes made of thermoplastic material
US4584170A (en) Method of making pipes by powder metallurgy and pipe blanks (semi-finished products) made in accordance therewith
US760150A (en) Art of manufacturing hollow glass articles.
US4334858A (en) Prevention of thermal spalling in ceramic products
JPH0515763B2 (es)
US500675A (en) Clemens schnell
US20070128443A1 (en) Method for altering the shape of a tube
JP3110357B2 (ja) ポリテトラフルオロエチレン樹脂成形品の製造方法
JPH024551B2 (es)
SU459434A1 (ru) Способ изготовлени сосудов с двойной стенкой из стекла
SU1159669A1 (ru) Способ изготовлени изделий из труднодеформируемых материалов
SU525635A1 (ru) Способ остекловывани металлической трубы
SU384671A1 (ru) Оправка для обжига полых изделий