US3519057A - Eliminating patterns from and hardening of shell molds - Google Patents

Eliminating patterns from and hardening of shell molds Download PDF

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Publication number
US3519057A
US3519057A US659182A US3519057DA US3519057A US 3519057 A US3519057 A US 3519057A US 659182 A US659182 A US 659182A US 3519057D A US3519057D A US 3519057DA US 3519057 A US3519057 A US 3519057A
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United States
Prior art keywords
mold
pattern
furnace
liquid
firing
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Expired - Lifetime
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US659182A
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English (en)
Inventor
Charles L Benson
William N Lenahan
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Howmet Turbine Components Corp
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Howmet Corp
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Assigned to HOWMET TURBINE COMPONENTS CORPORATION, A CORP.OF DE reassignment HOWMET TURBINE COMPONENTS CORPORATION, A CORP.OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HOWMET CORPORATON A CORP. OF DE
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B22C9/04—Use of lost patterns
    • B22C9/043—Removing the consumable pattern

Definitions

  • the art to which this invention pertains is the manufacture of refractory shell molds. It involves making a pattern of the desired casting in wax or similar readily fusible material, then forming a refractory shell mold by dip-coating the pattern a number of times with a liquid suspension of a fine-grained refractory which hardens on the pattern, then eliminating the pattern from within the mold built up in this manner, and finally firing the mold to the desired hardness in a furnace.
  • the pattern is melted out of the mold by burning a flammable liquid soaked into the mold, and the invention relates to improvements in that step of eliminating the pattern and the subsequent step of firing the mold in a furnace.
  • the improvements are predicated on the concept of firing the mold in the furnace very promptly after the flammable liquid has burned, or even commencing the firing prior to completion of the burning of the flammable liquid, so that the mold is not permitted to cool between the steps of burning the flammable liquid and firing in the furnace.
  • By avoiding such cooling little or no carbonized residue is allowed to form as a result of burning the flammable material and the time required for firing is appreciably reduced since only a minimum of oxidized material need be eliminated in the furnace.
  • a mold formed by successive dipping of the pattern in a slurry having a binder of hydrolyzed ethylsilicate or isopropyl silicate can be strengthened in its green state if it is heated, by burning a siliciferous liquid such as an acetone or ethanol based hydrolyzed ethyl silicate.
  • British patent specification No. 800,143 describes a method of eliminating patterns from shell molds which embodies these principles.
  • the present invention is directed to an improvement in methods of making a refractory shell mold as described above wherein the mold is formed on a fusible pattern and then soaked with a flammable liquid, the liquid is burned toheat the mold and melt the pattern material so that it flows therefrom, and the mold is fired to the desired hardness in a furnace.
  • the improvement comprises firing the mold in the furnace without first permitting substantial cooling thereof subsequent to the burning of the flammable liquid.
  • the mold is located in the furnace during burning of the liquid and the firing is commenced before the burning is completed.
  • a pattern of the desired casting is made of wax, a thermoplastic composition, or other suitable material.
  • the pattern is clipped in to a slurry comprising a silicacontaining binder and some other refractory (not necessarily silica) and the dip-coating adhering to the pattern is dusted with a relatively coarse refractory.
  • the slurry dip-coat may have a binder of hydrolyzed ethyl silicate or isopropyl silicate and be gelled in an atmosphere of ammonia gas for two or three minutes, or it may be bonded with colloidal silica. Successive dip-coatings are applied until a shell mold is built up on the pattern. At this point the mold is in the green state and the fusible pattern is to be eliminated.
  • the method of eliminating the pattern and firing the mold in accordance with the invention can be readily carried out on a conveyor 10 as shown in the accompanying drawing. It is adapted to carry molds 11 through a series of process stages indicated as 11A through 11G in the drawing. In the first stage at 11A the mold containing a fusible pattern is soaked by dipping, spraying or other suitable technique with a flammable liquid.
  • the liquid may be a fuel such as gasoline, hexane, acetone or alcohol, any of which is appropriate for use when colloidal silica is used as a bond for the refractory ofthe shell mold.
  • the mold when the slurry contains hydrolyzed ethyl or isopropyl silicate as a binder, the mold can be significantly strengthened by the use of a siliciferous flammable liquid such as an acetone or ethanol based hydrolyzed ethyl silicate, an isopropanol based colloidal silica, or an ethanol based hydrolyzed isopropyl silicate.
  • a siliciferous flammable liquid such as an acetone or ethanol based hydrolyzed ethyl silicate, an isopropanol based colloidal silica, or an ethanol based hydrolyzed isopropyl silicate.
  • the mold containing the pattern permeated with flammable liquid is placed on the conveyor 10 immediately ahead of an extended high temperature furnace 12 (e.g. about 1500 F.) through which the conveyor travels.
  • an extended high temperature furnace 12 e.g. about 1500 F.
  • the flammable liquid with which it is soaked is ignited, perhaps beneath a suitable hood 13 or other means for carrying off the gaseous products of combustion.
  • the conveyor 10 carries the mold into the furnace 12, where, as shown at 11C, burning of the flammable liquid continues.
  • the heat given off by the burning liquid is transferred so rapidly to the pattern that before the bulk of the pattern can undergo critical thermal expansion its outer surface liquefies and drains off.
  • a suitable pan 14 is provided beneath the conveyor 10 in this area at the beginning of the furnace 12 to collect the pattern material melted from the molds and drain it off to a suitable vessel 15.
  • Combustion of the flammable liquid may continue as the mold is carried by the conveyor 10 to a position shown at 11D, but by the time the mold advances appreciably into the furnace 12 as shown at 11E all of the flammable liquid has been consumed and the last remaining flowable pattern material has been melted out and carried away. By this time the heat of the furnace has taken effect and the refractory material begins to undergo hardening. No part of the mold is allowed to cool to any significant degree after combustion of the flamma ble liquid as shown at 11D and before heating by the furnace atmosphere. Consequently, virtually no carbonized Wax residue forms anywhere on or within the mold. It has been discovered that such formations will not take place when interim cooling is avoided.
  • the mold then continues on through the furnace 12 until its full high temperature strength has been developed near the exit of the furnace as shown at 11F. By that time, whatever remaining pattern material may have been left clinging to the mold surface has been oxidized and completely removed without going through a difficult stage of burning away dense carbonized matter. At the conclusion of the process, the mold emerges at 11G completely hardened, free of all undesirable residue, and emptied of its pattern.
  • the total time required for the process from the soaking step at 11A to completion at 11G is far less than for prior methods where the mold was cooled before firing, even disregarding the hold time taken for cooling in the prior method.
  • a method of making a refractory shell mold wherein the mold is formed on a fusible pattern and then soaked with a flammable liquid, the liquid is burned to heat the mold and melt the pattern material so that it flows therefrom, and the mold is fired to the desired hardness in a furnace, the improvement which comprises (a) firing the mold in the furnace without first permitting substantial cooling thereof subsequent to the burning of the flammable liquid, the mold being located in the furnace during at least the latter part of the burning of the liquid, and the firing being commenced before the burning is completed whereby the formation of any substantial amount of carbonized matter is prevented.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
US659182A 1967-08-08 1967-08-08 Eliminating patterns from and hardening of shell molds Expired - Lifetime US3519057A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US65918267A 1967-08-08 1967-08-08

Publications (1)

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US3519057A true US3519057A (en) 1970-07-07

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US659182A Expired - Lifetime US3519057A (en) 1967-08-08 1967-08-08 Eliminating patterns from and hardening of shell molds

Country Status (8)

Country Link
US (1) US3519057A (fr)
BE (1) BE717282A (fr)
CH (1) CH477930A (fr)
ES (1) ES354541A1 (fr)
FR (1) FR1602551A (fr)
GB (1) GB1208511A (fr)
NL (1) NL6809868A (fr)
SE (1) SE324038B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847202A (en) * 1973-03-02 1974-11-12 Trw Inc Microwave dewaxing
US5372177A (en) * 1993-05-13 1994-12-13 Foster; Glenn H. Method and apparatus for removing wax from casting mold
CN103418753A (zh) * 2012-05-18 2013-12-04 无锡蠡湖叶轮制造有限公司 醇基涂料的节能型固化流水线
CN105414478A (zh) * 2015-12-29 2016-03-23 葛全岭 一种精铸件消失模融蜡池结构及其融蜡方法
CN107635694A (zh) * 2015-10-13 2018-01-26 金属铸造技术股份有限公司 熔模模具浆料帘幕设备

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6951239B1 (en) * 2004-04-15 2005-10-04 United Technologies Corporation Methods for manufacturing investment casting shells
DE102005024207A1 (de) * 2005-05-25 2006-11-30 Ashland-Südchemie-Kernfest GmbH Verfahren zur Trocknung von Wasserschlichten

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB716394A (en) * 1952-04-03 1954-10-06 Shaw Processes Ltd Improvements in or relating to moulds for metal casting
US2930089A (en) * 1955-12-16 1960-03-29 Rolls Royce Precision casting
US3348605A (en) * 1962-12-19 1967-10-24 Heron John Aherne Method and apparatus for forming cast objects using expendable patterns

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB716394A (en) * 1952-04-03 1954-10-06 Shaw Processes Ltd Improvements in or relating to moulds for metal casting
US2930089A (en) * 1955-12-16 1960-03-29 Rolls Royce Precision casting
US3348605A (en) * 1962-12-19 1967-10-24 Heron John Aherne Method and apparatus for forming cast objects using expendable patterns

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847202A (en) * 1973-03-02 1974-11-12 Trw Inc Microwave dewaxing
US5372177A (en) * 1993-05-13 1994-12-13 Foster; Glenn H. Method and apparatus for removing wax from casting mold
CN103418753A (zh) * 2012-05-18 2013-12-04 无锡蠡湖叶轮制造有限公司 醇基涂料的节能型固化流水线
CN107635694A (zh) * 2015-10-13 2018-01-26 金属铸造技术股份有限公司 熔模模具浆料帘幕设备
US11786961B2 (en) 2015-10-13 2023-10-17 Metal Casting Technology, Inc. Investment mold slurry curtain apparatus
CN105414478A (zh) * 2015-12-29 2016-03-23 葛全岭 一种精铸件消失模融蜡池结构及其融蜡方法
CN105414478B (zh) * 2015-12-29 2017-12-05 湖南省金峰机械科技有限公司 一种精铸件消失模融蜡池结构及其融蜡方法

Also Published As

Publication number Publication date
BE717282A (fr) 1968-12-02
CH477930A (fr) 1969-09-15
GB1208511A (en) 1970-10-14
SE324038B (fr) 1970-05-19
NL6809868A (fr) 1969-02-11
ES354541A1 (es) 1969-11-16
FR1602551A (fr) 1970-12-28

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Date Code Title Description
AS Assignment

Owner name: HOWMET TURBINE COMPONENTS CORPORATION 825 THIRD AV

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. SUBJECT TO AGREEMENT DATED DECEMBER 31, 1975.;ASSIGNOR:HOWMET CORPORATON A CORP. OF DE;REEL/FRAME:004164/0321

Effective date: 19830705