U.S. patent application number 16/490067 was filed with the patent office on 2020-04-02 for method and apparatus for reusing green sand.
This patent application is currently assigned to Sintokogio, Ltd.. The applicant listed for this patent is Sintokogio, Ltd.. Invention is credited to Kunihiro HASHIMOTO, Junichi IWASAKI, Hiroyasu MAKINO.
Application Number | 20200101524 16/490067 |
Document ID | / |
Family ID | 64737524 |
Filed Date | 2020-04-02 |
![](/patent/app/20200101524/US20200101524A1-20200402-D00000.png)
![](/patent/app/20200101524/US20200101524A1-20200402-D00001.png)
![](/patent/app/20200101524/US20200101524A1-20200402-D00002.png)
United States Patent
Application |
20200101524 |
Kind Code |
A1 |
MAKINO; Hiroyasu ; et
al. |
April 2, 2020 |
METHOD AND APPARATUS FOR REUSING GREEN SAND
Abstract
A method and an apparatus for effectively reusing the green sand
that would otherwise overflow the line for molding to be disposed
of, even though it is fully usable, are provided. The method for
reusing green sand comprising the steps of treating the green sand
with ultrasonic waves in water; separating a mixture that is
obtained by the step of treating the green sand with ultrasonic
waves to form a suspension and to form residual particles of the
sand; circulating the suspension to then proceed to the step of
treating the green sand with ultrasonic waves so that the
suspension is concentrated; storing the concentrated suspension;
and feeding the stored suspension to green sand by a predetermined
amount when green sand is mulled.
Inventors: |
MAKINO; Hiroyasu; (Aichi,
JP) ; HASHIMOTO; Kunihiro; (Aichi, JP) ;
IWASAKI; Junichi; (Aichi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sintokogio, Ltd. |
Aichi |
|
JP |
|
|
Assignee: |
Sintokogio, Ltd.
Aichi
JP
|
Family ID: |
64737524 |
Appl. No.: |
16/490067 |
Filed: |
January 29, 2018 |
PCT Filed: |
January 29, 2018 |
PCT NO: |
PCT/JP2018/002613 |
371 Date: |
August 29, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22C 5/14 20130101; B22C
5/00 20130101 |
International
Class: |
B22C 5/14 20060101
B22C005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2017 |
JP |
2017-120202 |
Claims
1. A method for reusing green sand comprising the steps of:
treating the green sand with ultrasonic waves in water; separating
a mixture that is obtained by the step of treating the green sand
with ultrasonic waves to form a suspension and to form residual
particles of the sand; circulating the suspension to then proceed
to the step of treating the green sand with ultrasonic waves so
that the suspension is concentrated; storing the concentrated
suspension; and feeding the stored suspension to green sand by a
predetermined amount when green sand is mulled.
2. The method for reusing the green sand of claim 1, further
comprising: a step of removing an Oolitic layer from the residual
particles of the sand that have been separated in the step of
separating.
3. An apparatus for reusing green sand comprising: an ultrasonic
washer for treating green sand with ultrasonic waves in water, the
green sand having been used; a separator for separating a mixture
that is obtained by the ultrasonic washer to form a suspension and
to form residual particles of the sand; an apparatus for
circulating and making the suspension thicker, which apparatus
measures a degree of concentration of the separated suspension,
which apparatus returns the suspension to the ultrasonic washer if
the degree of concentration that is measured equals, or is below, a
predetermined degree of concentration, and which apparatus feeds
the suspension to a storage tank for storing the suspension if the
degree of concentration that is measured is over the predetermined
degree of concentration; the storage tank that stores the
suspension of which the degree of concentration is over the
predetermined degree of concentration; and a volumetric feeder that
feeds the stored suspension by a predetermined amount when the
green sand is mulled.
4. The apparatus for reusing the green sand of claim 3, further
comprising: a system for mechanically reclaiming the green sand
that removes an Oolitic layer from the residual particles of the
sand that have been separated in the separator.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method and an apparatus
to efficiently reuse green sand after molding.
BACKGROUND ART
[0002] In green sand molding, since a core is used, an organic
binder that has been used for forming the core dissipates so that a
part of the core sand become single grains to be mixed in the green
sand. Thus the total amount of the green sand in the line for
molding gradually increases, to overflow. Thus the part of the
green sand that is used in the line for molding must be disposed
of. Further, the clay content is reduced because of the increase of
the amount of the green sand. Thus clay must be added. This
increases costs.
[0003] In this situation, materials that adhere to the surfaces of
the sand are stripped, separated, and removed by mechanical means.
Then the sand is reclaimed to be used for molds. The coating
materials that have been stripped and separated are collected by a
dust collector in the same way as for dust.
[0004] The coating materials that have been stripped and separated
include crushed sand as fine powder and clay that has been
denatured by heat from poured molten metal. However, regarding
active clay, which is an effective hinder, it is difficult to
separate it from the coating materials that have been stripped and
separated. Thus, as in Patent Literature 1, water is added to dust
that has been collected and that includes the coating materials
that have been stripped and separated to be reused as a paste-like
sealing material for molds. But most of the dust is usually
disposed of.
[0005] For example, in Patent Literature 2, a method for collecting
active clay, which is an effective hinder, from the coating
materials that have been stripped and separated, is disclosed. In
that method collected dust that includes the coating materials that
have been stripped and separated is agitated and suspended in
water. Then a supernatant liquid that includes bentonite and
organic materials is separated. The supernatant liquid is used in a
line for molding.
[0006] However, these methods are insufficient to reuse green sand
that is to be disposed of because of overflow, by efficiently
separating active clay, which can be reused.
[0007] The present invention aims to provide a method and an
apparatus for effectively reusing green sand that would otherwise
he disposed of because of overflow, even though it is usable.
PRIOR-ART PUBLICATION
Patent Literature
[0008] [Patent Literature 1]
[0009] Japanese Patent Laid-open Publication No. 2003-290872 [0010]
[Patent Literature 2]
[0011] Published PCT Japanese Translation No. 2004-532129
SUMMARY OF INVENTION
[0012] (Italics: Claim language)
[0013] A method for reusing green sand of the present invention
comprises the step of treating the green sand with ultrasonic waves
in water. It also comprises the step of separating to separate a
mixture that is obtained by the step of treating the green sand
with ultrasonic waves to form a suspension and to form residual
particles of the sand. It also comprises the step of circulating to
circulate the suspension to then proceed to the step of treating
the green sand with ultrasonic waves so that the suspension is
concentrated. It also comprises the step of storing to store the
concentrated suspension. It also comprises the step of feeding to
feed the stored suspension to green sand by a predetermined amount
when green sand is mulled.
[0014] By treating green sand with ultrasonic waves, active clay
can be efficiently separated from it to obtain a suspension that
includes the active clay. By circulating the suspension as water
for treating green sand with ultrasonic waves, the suspension can
be concentrated. Thus the clay of the green sand can be efficiently
reused.
[0015] The method for reusing the green sand of the present
invention preferably includes the step of removing an Oolitic layer
from the residual particles of the sand that have been separated in
the step of separating.
[0016] By removing the Oolitic layer from the residual particles of
the sand, they can be reused as core sand, etc.
[0017] An apparatus for reusing green sand of the present invention
comprises an ultrasonic washer for treating green sand with
ultrasonic waves in water, the green sand having been used. It also
comprises a separator for separating a mixture that is obtained by
the ultrasonic washer to form a suspension and to form residual
particles of the sand. It also comprises an apparatus for
circulating and making the suspension thicker, which apparatus
measures a degree of concentration of the separated suspension,
which apparatus returns the suspension to the ultrasonic washer if
the degree of concentration that is measured equals, or is below, a
predetermined degree of concentration, and which apparatus feeds
the suspension to a storage tank for storing the suspension if the
degree of concentration that is measured is over the predetermined
degree of concentration. It also comprises the storage tank that
stores the suspension of which the degree of concentration is over
the predetermined degree of concentration. It also comprises a
volumetric feeder that feeds the stored suspension by a
predetermined amount when the green sand is mulled.
[0018] By treating the green sand with ultrasonic waves, active
clay is efficiently removed from the green sand to cause the
suspension to contain the active clay. By using such a suspension
as water for the ultrasonic treatment, the suspension can be
concentrated so that the clay can be efficiently used as the clay
content of the green sand.
[0019] The apparatus for reusing the green sand of the present
invention preferably comprises a system for mechanically reclaiming
the green sand that removes an Oolitic layer from the residual
particles of the sand that have been separated in the
separator.
[0020] By removing the Oolitic layer from the residual particles of
the sand, they can be reused as core sand, etc.
[0021] As discussed above, the present invention provides a method
for effectively reusing the green sand that would otherwise
overflow from the line for molding to be disposed of, even though
it is fully usable.
[0022] The basic Japanese patent application, No. 2017-120202,
filed Jun. 20, 2017, is hereby incorporated by reference in its
entirety in the present application.
[0023] The present invention will become more fully understood from
the detailed description given below. However, the detailed
description and the specific embodiments are only illustrations of
the desired embodiments of the present invention, and so are given
only for an explanation. Various possible changes and modifications
will be apparent to those of ordinary skill in the art on the basis
of the detailed description.
[0024] The applicant has no intention to dedicate to the public any
disclosed embodiment. Among the disclosed changes and
modifications, those which may not literally fall within the scope
of the present claims constitute, therefore, a part of the present
invention in the sense of the doctrine of equivalents.
[0025] The use of the articles "a," "an," and "the" and similar
referents in the specification and claims are to be construed to
cover both the singular and the plural form of a noun, unless
otherwise indicated herein or clearly contradicted by the context.
The use of any and all examples, or exemplary language (e.g., "such
as") provided herein is intended merely to better illuminate the
invention, and so does not limit the scope of the invention, unless
otherwise stated.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a system flowchart that illustrates the process
for carrying out the work.
[0027] FIG. 2 is a graph that shows rates of collecting active clay
from green sand by an ultrasonic treatment.
DESCRIPTION OF EMBODIMENTS
[0028] Below the present invention is discussed with reference to
FIG. 1.
[0029] (1) Excess green sand that is generated in a line for
molding is transported to a hopper 0 for sand that has overflowed.
It is temporarily stored there.
[0030] (2) The green sand that has been stored in the hopper for
the sand that has overflowed is fed to the ultrasonic washer 1 by
means of a device for discharging a fixed amount of the sand. Water
that contains no additives, such as a parting agent, is also fed
there when the weight of the water is three to ten times the weight
of the sand. The reason the water that contains no additives, such
as a parting agent, is so fed is based on the cost and toxicity of
the additives. If the degree of concentration of the suspension,
which is discussed in No. (4) below, is equal to, or below, a
reference value, the suspension is supplied to the ultrasonic
washer 1. By the ultrasonic washer 1 ultrasonic waves generated at
20-400 kHz are applied to the mixture of the green sand and the
water for a period that is appropriate for the output of Ultrasonic
waves by an ultrasonic generator (the step of treating the green
sand with ultrasonic waves). The coating materials that adhere to
the surfaces of the green sand are stripped by that ultrasonic
treatment. Thus the suspension wherein the coating materials that
have been stripped are suspended in the water and the residual
particles of the sand from which the coating materials have been
stripped are obtained.
[0031] (3) The mixture of the green sand and the water that has
been subjected to the step of treating the green sand with
ultrasonic waves is fed to the separator 2 to be separated into the
suspension and the residual particles of the sand (the step of
separating). The separator 2 may be a separator of a settling-type
or of a filtering-type.
[0032] (4) The degree of concentration of the suspension is
measured. If it is equal to, or below, the reference value, then
the suspension is circulated to an apparatus 5 for circulating and
making the suspension thicker and fed into the ultrasonic washer 1
so that the suspension is made thicker (the step of circulation).
The degree of concentration of the suspension is measured by any
known densitometer, such as an optical densitometer that uses
reflected light or transmitted light. A fixed amount of the green
sand that has been stored in the hopper 0 for the sand that has
overflowed is fed to the ultrasonic washer 1. The degree of
concentration of the suspension is again measured after the step of
treating the green sand with ultrasonic waves and the step of
separating. If it is still equal to, or below, the reference value,
the process of (4) is repeated so that the suspension is made
thicker. As an example, the reference value for the degree of
concentration of the suspension is about 20 wt %. If the degree of
concentration of the suspension is low, a problem occurs, since too
much water is added when a required amount of the active clay that
is contained in the suspension is added to the green sand.
[0033] (5) A suspension that has a degree of concentration over the
reference value is stored in the storage tank 3 (the step of
storing). The storage tank 3 is preferably equipped with a stirring
device to prevent settling.
[0034] (6) The suspension in the storage tank is fed to an
apparatus 6 for kneading the green sand by a fixed amount by means
of a volumetric feeder 4 (the step of feeding) when the green sand
is kneaded. The volumetric feeder 4 may be a slurry pump. The
active clay that is contained in the suspension is reused through
the steps (1) to (6). In this way about 50% of the active clay that
is to be supplied can be saved.
[0035] (7) The residual particles of the sand that have been
generated in the process to separate the suspension from the
residual particles of the sand are reclaimed by removing the
Oolitic layer by means of the system 7 for mechanically reclaiming
the green sand (the step of removing the layer). The Oolitic layer
that strongly adheres to the surfaces of the residual particles of
the sand can be removed by the system 7 for mechanically reclaiming
the green sand. This system 7 preferably performs a drying process.
It may be any known system. For example, a system for applying
force from friction to the sand may be used, wherein the residual
particles of the sand are supplied to a cup-like rotor that rotates
and wherein blades are provided above the wall of the rotor. When
the rotor rotates, the residual particles of the sand scrub each
other or collide with the blades so that the Oolitic layer is
cracked and stripped from the surfaces of the particles of the
sand. Incidentally, the Oolitic layer is a layer of fine powder
that has low resistance to heat. This layer is strongly burned on
the surfaces of the particles of the sand. The reclaimed sand can
be reused as core sand, etc.
[0036] Working Example
[0037] The degrees of separating active clay from the green sand by
means of ultrasonic waves and by means of mechanical agitation are
tested for comparison. The results are shown in FIG. 2. The results
were evaluated by The Method for Evaluating Active Clay (TJFS-205),
issued by Tokai Branch, Japan Foundry Engineering Society. The
content of the active clay is measured as below. 50 cm.sup.3 of a
2% solution of sodium pyrophosphate is added to 5 g of green sand,
and then is subjected to ultrasonic washing for 10 minutes. The
sodium pyrophosphate has abilities to strip the coating materials
on the surfaces of the particles of the sand and to disperse them.
The supernatant liquid is titrated by a methylene blue solution of
1/100 concentration. The content of the active clay is determined
by the consumption of the solution.
[0038] By this method, sodium pyrophosphate, which has a function
for causing a dispersion, is added. However, in the present
invention no dispersing agent is added. Thus distilled water, which
contains no dispersing agent, is used to compare possible
collections of the active clay by means of ultrasonic waves and by
means of mechanical agitation.
[0039] The green sand is subjected to the ultrasonic treatment by
using distilled water, which contains no dispersing agent, so that
74% of the active clay in the green sand is included in the
suspension to be collected. Thirty-eight percent of the active clay
is separated and collected by means of mechanical agitation.
[0040] From the above experiments, it is seen that 70% or more of
the active clay has been collected by the ultrasonic treatment by
using distilled, water. This method is found to be very
industrially useful.
[0041] The reference signs used in the present specification and
the drawings are as follows: [0042] 0 the hopper for the sand that
has overflowed [0043] 1 the ultrasonic washer [0044] 2 the
separator [0045] 3 the storage tank [0046] 4 the volumetric feeder
[0047] 5 the apparatus for circulating and making the suspension
thicker [0048] 6 the apparatus for kneading the green sand [0049] 7
the system for mechanically reclaiming the green sand
* * * * *