# US 10,766,063 B2 · Evaporative pattern casting method

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- Number: US 10,766,063 B2
- Document ID: US10766063B2
- Status: Granted
- Kind: B2
- Application number: 16/074,203
- Filed: 2017-01-26
- Published: 2019-12-26
- Granted: 2020-09-08
- Earliest claimed: 2016-02-02
- Assignees: Kobe Steel, Ltd.
- Applicants: Kobe Steel, Ltd.
- Inventors: Eisuke Kurosawa; Kazuyuki Tsutsumi
- Web page: https://patentgrep.com/patent/US10766063B2

## CPC

- B22C 3/00: Selection of compositions for coating the surfaces of moulds, cores, or patterns
- B22C 9/046: {Use of patterns which are eliminated by the liquid metal in the mould}
- B22C 7/023: {Patterns made from expanded plastic materials}
- B22C: FOUNDRY MOULDING (moulding refractory materials in general B28B)

## Abstract

A mold wash is used in a casting method using a lost foam to make a casting having a hole with a diameter of 12 mm or less. The casting method includes determining a thermal decomposition amount ΔC(θ,t) [wt %] of a resin binder when the mold wash is exposed at a temperature θ [° C.] for a time t [sec], and determining a room temperature transverse rupture strength σb(θ,t) [MPa] of the mold wash after receiving thermal loads, and performing casting with the mold wash having the room temperature transverse rupture strength σb(θ,t) after receiving thermal loads being equal to or larger than a threshold value σcr [MPa].

## Claims

### Claim 1

A casting method using a lost foam, comprising embedding, in foundry sand, a casting pattern formed by applying a mold wash to a surface of a foam pattern; and pouring a molten metal into the casting pattern and losing the foam pattern to replace the foam pattern with the molten metal, thereby making a casting with a thickness T [mm], the casting including a hole with a diameter of 12 mm or less and a length l [mm],
the casting method comprising the steps of:
determining a thermal decomposition amount ΔC(θ,t) [wt %] of a resin binder when the mold wash is exposed at a temperature θ [° C.] for a time t [sec], from the following formulae (1) to (3), wherein ΔCsat(θ) [wt %] is a critical thermal decomposition amount of the resin binder contained in the mold wash at a temperature θ [° C.], kd [1/sec] is a thermal decomposition rate constant of the resin binder, θs [° C.] is a temperature at which thermal decomposition of the resin binder starts, and A, α, and τ3 are material parameters relying on a material of the mold wash, respectively;
determining a room temperature transverse rupture strength σb(θ,t) [MPa] of the mold wash after receiving thermal loads from the following formula (4), wherein σc0 [MPa] is a room temperature transverse rupture strength of the mold wash before receiving thermal loads, σc1 [MPa] is a room temperature transverse rupture strength of the mold wash after the resin binder is completely thermally decomposed, σs(θ,t) [MPa] is a strength increase caused by reaction and sintering among aggregates contained in the mold wash, and γ is a material parameter relying on the material of the mold wash; and
performing casting with the mold wash having the room temperature transverse rupture strength σb(θ,t) after receiving thermal loads being equal to or larger than a threshold value σcr [MPa]:
ΔC(θ,t)=ΔCsat(θ)·{1−exp(−kdt)} (1)
ΔCsat(θ)=tanh{β(θ−θs)}×100 (2)
kd=A exp(αθ) (3)
σb(θ,t)=σc0−(σc0−σc1)tanh(γΔC(θ,t))+σs(θ,t) (4).

### Claim 2 (depends on 1)

The casting method using a lost foam according to claim 1, wherein the threshold value σcr is 0.56 MPa.

### Claim 3 (depends on 2)

The casting method using a lost foam according to claim 2, wherein the mold wash is twice applied to the foam pattern for making a casting with a thickness T of 25 mm or less, the casting including a hole with a diameter of 8 mm or more and a length l of 100 mm or less.

### Claim 4 (depends on 1)

The casting method using a lost foam according to claim 1, wherein when the thermal decomposition amount ΔC(θ,t) of the resin binder is 83 wt % or more, the threshold value σcr is 0.56 MPa.

### Claim 5 (depends on 4)

The casting method using a lost foam according to claim 4, wherein the mold wash is twice applied to the foam pattern for making a casting with a thickness T of 25 mm or less, the casting including a hole with a diameter of 8 mm or more and a length l of 100 mm or less.

### Claim 6 (depends on 1)

The casting method using a lost foam according to claim 1, wherein the mold wash is twice applied to the foam pattern for making a casting with a thickness T of 25 mm or less, the casting including a hole with a diameter of 8 mm or more and a length l of 100 mm or less.