Mold manufacturing method

Patent metadata

Field	Value
Publication number	US-10589345-B2
Application number	US-201716330752-A
Country	US
Kind code	B2
Filing date	Sep 1, 2017
Priority date	Sep 7, 2016
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A mold molding method includes a binder reaction amount calculation step of calculating a reaction amount ΔC(θ, t i ) [wt %] (i=1, 2) of a binder, a specimen room temperature compressive strength calculation step of calculating room temperature compressive strength σ c (θ, t) [MPa] of a specimen, a mold room temperature compressive strength prediction step of predicting room temperature compressive strength σ ca (θ, t) of the mold in advance, and a mold room temperature compressive strength extraction step of extracting room temperature compressive strength σ ce (θ, t) of the mold. When the mold is actually molded, the model is removed just after elapse of the time t 1 , as one of the molding condition parameters which satisfies the room temperature compressive strength σ ce (θ, t).

First claim

The invention claimed is:

1. A mold molding method that molds a mold by filling a frame, in which a model is placed, with self-hardening sand obtained by kneading sand, a binder, and a hardening accelerator, and removing the model after the self-hardening sand is hardened, so that a shape of the model is transferred to the hardened self-hardening sand,
the mold molding method comprising:
a binder reaction amount calculation step of calculating a reaction amount ΔC(θ, t i ) [wt %] (i=1, 2) of the binder based on the following equations (1) and (2) using, as molding condition parameters when a specimen is molded using the self-hardening sand, temperature θ [° C.] of the sand before kneading, time t 1 [min] from an end of the kneading to a time point when the model has been removed from the hardened self-hardening sand, and time t 2 [min] from the time point just after the model has been removed from the hardened self-hardening sand to a time point just before the specimen is subjected to a compression test;
a specimen room temperature compressive strength calculation step of calculating room temperature compressive strength σ c (θ, t) [MPa] of the specimen by substituting the reaction amounts ΔC(θ, t 1 ) and ΔC(θ, t 2 ) calculated in the binder reaction amount calculation step into the following equation (3);
a mold room temperature compressive strength prediction step of predicting room temperature compressive strength σ ca (θ, t) of the mold in advance by applying the room temperature compressive strength σ c (θ, t) of the specimen calculated in the specimen room temperature compressive strength calculation step to room temperature compressive strength σ ca (θ, t) of the mold when the mold is molded using the self-hardening sand under the molding condition parameters; and
a mold room temperature compressive strength extraction step of extracting room temperature compressive strength σ ce (θ, t) of the mold, under which the mold can be molded without damages and the model can be removed, from the predicted room temperature compressive strength σ ca (θ, t) of the mold by a test in advance,
wherein when the mold is actually molded, the model is removed just after elapse of the time t 1 , as one of the molding condition parameters which satisfies the room temperature compressive strength σ ce (θ, t) extracted in the mold room temperature compressive strength extraction step:
Δ C (θ, t i )=Δ C sat ·{1−exp(− k di t i )}  (1)

wherein
ΔC sat : a saturated reaction amount [wt %] of the binder, and
k di (i=1, 2): reaction rate constant [l/min] of the binder;
k di =A i exp(α i θ)  (2)

wherein
A i (i=1, 2) and α i (i=1, 2): parameters dependent on kind of the binder used; and
σ c (θ, t )={tan h (β·Δ C (θ, t 1 ))+γ}+{tan h (ε(θ)·Δ C (θ, t 2 )−η)}  (3)

wherein
β, γ and η: material parameters, and
ε: constant determined by the temperature θ.

2. The mold molding method according to claim 1 , wherein the room temperature compressive strength σ ce (θ, t) satisfies: 0.5 [MPa]≤σ ce (θ, t) [MPa]≤2.2 [MPa].

3. The mold molding method according to claim 2 , wherein the temperature θ of the sand is 5 to 30° C.

4. The mold molding method according to claim 1 , wherein the temperature θ of the sand is 5 to 30° C.

Assignees

• Kobe Steel Ltd

Inventors

• Takagawa Yusaku
• Tsutsumi Kazuyuki

Classifications

• B22C9/00

  Moulds or cores (uniquely adapted to particular casting processes B22D); Moulding processes · CPC title

• B22C9/02 Primary

  Sand moulds or like moulds for shaped castings · CPC title

• B22C1/22 Primary

  of resins or rosins · CPC title