JPH0347647A - Continuous production of sand mold for casting - Google Patents

Abstract

PURPOSE:To prolong a pot life by introducing a part of a resin coated sand consisting of a binder soln. contg. a phenolic resin, etc., and a solvent, and sand into a metallic mold for sand mold casting and adding the solvent for the binder to the remaining part of the above-mentioned resin coated sand by a method for introducing a hardener therein. CONSTITUTION:A part of the resin coated sand consisting of the binder soln. contg. the phenolic resin, polyisocyanate compd. and solvent and the sand is introduced into the metallic mold for sand mold casting and thereafter, the hardener is introduced into the metallic mold. The solvent for the binder is properly added to the remaining part of the above-mentioned resin coated sand. The flowability of the resin coated sand right after the prepn. thereof is nearly assured. The resin coated sand is, therefore, introduced at the sufficient packing density into the metallic mold and the high-strength and mold for casting is produced by curing. Since the pot life of the resin coated sand is greatly extended in this way, the high-strength sand mold for casting is easily, economically and continuously mass produced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for increasing the pot life of resin-coated sand.
This invention relates to a method for continuously manufacturing high-strength foundry sand molds in large quantities.

[Conventional Technology J Conventionally, as an industrial manufacturing method for high-strength foundry sand molds,
The Ashland method (for example, cold box method, no-bake method) is known, which is advantageous in terms of energy consumption because it does not require heating of the resin-coated sand during its production.

As an example, a method for manufacturing a foundry sand mold by the reed 1 land cold box method will be specifically explained as follows.

A first component solution consisting of a phenolic resin and a solvent.

The first one consists of a polyisocyanate compound and a solvent! Resin-coated sand is prepared by mixing the component solution and foundry river sand in a mixer, and is stored in a sand magazine (sand storage tank). The sand magazine is placed above the mold during sand mold making, and by blowing air from the top of the sand magazine, P! 4. Blow into the coated sand mold.

The blown resin-coated sand is then hardened at room temperature by passing through a hardening agent such as amine to form a foundry sand mold.

According to conventional methods, the amount of resin-coated sand stored in the sand magazine was in the range of several tens to hundreds of times the mold capacity, but from the viewpoint of sand mold production efficiency, this multiplier is not large enough. However, as the amount of resin-coated sand to be stored increases, the number of times air is blown into the resin-coated sand during sand mold making increases, and the waiting time for the resin-coated sand also increases, making it difficult to lose the solvent. As a result, the sand movement of the I#l oil coating is reduced. As a result, the packing density of the resin-coated sand into the mold decreases, and the strength of the manufactured sand mold also decreases.

Therefore, in order to efficiently produce high-strength foundry sand molds, we have developed a method for manufacturing resin-coated sand with a long pot life. A method of coating sand with a solvent was known (see Japanese Patent Publication No. 5B-46376).
.

[Problem to be solved by the invention]

However, in particular, ■ When the amount of sand used per hour is small compared to the amount stored in the sand magazine ■ When the amount of sand used per hour is small compared to the number of times of blowing ■ When the sand FM right or in a high humidity environment Even with the manufacturing method of foundry sand molds using resin-coated foundry sand, increasing the amount of resin-coated sand stored in the sand magazine still lowers the packing density of the resin-coated sand and reduces the strength of the sand mold, making it impractical for practical use. There was a problem in that it was not possible to continuously manufacture large quantities of foundry sand molds.

The present invention solves the problems of the conventional continuous manufacturing method of foundry sand molds, and aims to provide a method for continuously manufacturing high-strength foundry sand molds in large quantities.

[Means for Solving the Problems 1] According to the present invention, a part of resin-coated sand made of sand and a binder solution containing a phenol resin, a polyisocyanate compound, and a solvent is introduced into a mold for sand mold production. , a continuous method for manufacturing a foundry sand mold comprising repeating various steps of introducing a curing agent into the mold, characterized in that a binder solvent is appropriately added to the remainder of the resin-coated sand. A flii notation method is provided.

The binder solution used in the present invention comprises a phenolic resin, a polyisocyanate compound and a solvent.

Here, the phenol resin is a phenol having a benzyl ether group in its molecule, a novolak, or a resin derived from these.

Examples of the polyisocyanate compound include diphenylmethane diisocyanate, hexamethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

As the solvent for the binder, any solvent used in the preparation of resin-coated sand in the Ashland process can be used in the present invention.

Specifically, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogenated hydrocarbons.

Organic solvents such as ketones, esters, ethers, and alcohols can be used alone or in combination. From the viewpoint of the temperature during the manufacturing process of the hA fat-covered sand mold, the toxicity of the solvent, odor, economic efficiency, etc., a relatively high boiling point (
For example, using an aliphatic hydrocarbon-based, alicyclic hydrocarbon-based, aromatic hydrocarbon-based, ester-based, or ketone-based organic solvent with a temperature of 180'C or higher) alone or in combination. is preferred.

Specifically, as an aliphatic hydrocarbon solvent.

For example, n-hexane, n-hebutane, isooctane, etc.
Examples include kerosene, light oil, heavy oil, petroleum spirit, petroleum ether, petroleum benzene, and the like. Examples of the alicyclic hydrocarbon solvent include cyclohexane and ethylcyclohexane. Examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, and ethylbenzene. Examples of the halogenated hydrocarbon solvent include trichlene and chlorobenzene. Examples of the ketone solvent include methyl edyl ketone, methyl isobutyl ketone, isophorone, and cyclohexanone.

Ester solvents include ethyl acetate, dimethyl adipate, diethyl adipate, dimethyl glutarate, dimethyl succinate, dibutyl succinate, diethyl oxalate,
Examples include diethyl phthalate. Examples of the ether solvent include isopropyl ether and 1,4-dioxane, and examples of the alcohol solvent include ethanol, ethylene glycol, isopropanol, and furfuryl alcohol.

The binder solution may contain other components such as anti-deterioration agents and anti-drying agents, if desired.

The sand used in the present invention is finely powdered sand.

Although all kinds of sand including viscous sand, recycled sand, etc. are used, ordinary foundry sand is preferable, and sand of about 50 to 600 μm is particularly preferable.

The proportion of phenol resin, polyisocyanate compound, or solvent to sand is determined based on the strength of the sand mold.
Preferably, each content is in the range of 0.01 to 10% by weight, particularly preferably 0.1 to 5.0% by weight, based on the sand.

Preparation of resin-coated sand involves, for example, mixing sand and a binder solution consisting of a phenolic resin, a polyisocyanate compound, and a solvent, preferably at a temperature in the range of -10 to 50°C, using a mixer so that the four components are uniformly mixed. This can be done by thoroughly kneading the mixture.

It is particularly preferable that the binder γ8 liquid is prepared in advance as a phenol resin solution and an incyanate compound solution, and that both are added to the sand at the time of crosstalk with the sand.

The prepared resin-coated sand is stored in a sand magazine, and a desired amount of resin-coated sand is introduced into a sand mold manufacturing mold by, for example, blowing with air. A foundry sand mold is manufactured by introducing into the mold a curing agent commonly used in the land method in an amount sufficient to harden the sand mold.

Next, solvent vapor is continuously added to the unused resin-coated sand remaining in the sand magazine using an oiler, etc., and the desired amount of resin-coated sand is introduced into the sand mold manufacturing mold. Next, by repeating the steps of introducing a hardening agent, foundry sand molds can be manufactured continuously.

The solvent used here is of the same type as the binder solvent described above, but it may be the same or different from the solvent used in preparing the resin-coated sand.

The amount of solvent in the resin MRU sand remaining at any point in the continuous production of foundry sand molds is:

Since it varies depending on various conditions such as the type of solvent used, the temperature during the sand mold manufacturing process, the operating method, and the weight of the sand mold to be manufactured, it is necessary to adjust the amount of solvent added accordingly. From the point of view of extending the pot life of resin-coated sand and ensuring the strength of the sand, for example, the solvent content immediately after preparation of resin-coated sand (i.e., the amount of diaphragm in resin-coated sand is Preferably, 10 to 80% of the initial content ff1) of solvent is added evenly to the resin-coated sand in a continuous sand casting process.

Particular preference is given to adding solvent in an amount of 15 to 50%.

A method of adding a solvent to the remaining resin-coated sand is to add resin 1t1)'I! from the opening at the top of the sand magazine. There are methods such as spraying the solvent directly onto the sand, and using air containing solvent vapor or atomized solvent when introducing the resin-coated sand into the mold.

[Effect]

During the manufacturing process of foundry sand molds, when the solvent in the resin-coated sand is lost, its fluidity is impaired.

Therefore, if a solvent is appropriately added to the resin-coated sand in the production of the second and subsequent foundry sand molds in the continuous production of sand molds, the fluidity of the resin 'IIrH sand immediately after its preparation is almost ensured. Therefore, the resin-coated sand is introduced into the mold at a sufficient packing density, and a high-strength foundry sand mold is manufactured by curing.

That is, by adding a solvent to the resin-coated sand in the continuous production of foundry sand molds, the time during which the resin-coated sand prepared in large quantities at one time can be used for the continuous mass production of sand molds is significantly extended. It became possible to do so.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Hereinafter, all "parts" mean "parts by weight" and all "%" mean "% by weight".

X Kekaiyu Hodogaya Chemical Industry (Kiku made benzyl ether group-containing phenol resin 52.0%, succinic acid dimethyl ester 17.5%
%, petroleum solvent (5W-1800 manufactured by Marukubi Sekiyu ■) 30.
Prepare a solution consisting of 5% and proceed! A component solution was prepared.

Prepare a solution consisting of 75.0% diphenylmethane diisocyanate (MR-200, manufactured by Nippon Polyurethane Industries) and 25.0% petroleum solvent (IP-150, manufactured by Idemitsu Kosan), and add the first) component solution. did.

Adding 3080 parts of the above No. 1 component solution and 3080 parts of the above 1I component solution to 280000 parts of water-washed Enshu sand for foundry, the mixture was kneaded for 60 seconds at 14 Or, p, m using a grade mixer to obtain a resin. 286,160 parts of coated sand were prepared. The prepared resin-coated sand was transferred into a sand magazine.

Air was blown into the sand magazine at a gauge pressure of 3.0 kg/crn twice for 2 seconds each, and the resin-coated sand was blown into the mold for manufacturing the camshaft core. This process was carried out for a total of 4 minutes. Then, resin-coated sand was blown into 60 molds for manufacturing camshaft cores at a rate of 2.5 kg/
After gassing triethylamine with a generator for 1 second at a gauge pressure of crn' and permeating it into the mold for curing, air purging was performed at a gauge pressure of 3.0 kg/crrl, and a camshaft of 250 g was poured into the camshaft. A total of 60 child sand molds were manufactured.The working temperature and the sand temperature were both approximately 20°C, the relative humidity was 56%, and the machine used was a cold box machine manufactured by Shinto Kogyo ■.

A series of the above steps such as blowing the resin-coated sand into the gold and curing were carried out 30 minutes after the preparation of the resin-coated sand.
After 0 minutes, 80 minutes, 100 minutes, 120 minutes, and 140 minutes, the process was repeated 60 times each, for a total of 420 times.A 250g ff1fl camshaft core was produced in 140 minutes from the initial sand mold production. A total of 420 pieces of sand were manufactured. In addition,
Here, resin>1) 1) In the step of blowing sand into the mold (140 minutes), the air is petroleum-based solvent (5W-1800 manufactured by Marukubi Sekiyu and IP-150 manufactured by Idemitsu Kosan).
After preparing the resin-coated sand, 30 minutes, 60 minutes, 80 minutes, 100 minutes, and 120 minutes have passed through an oiler containing this solvent. The series of successive steps was carried out such that 90 parts of the solvent, 540 parts in total, were added evenly to the resin-coated sand.

The tensile strength of the sand mold after 10 minutes of manufacture is 42
6.6 to 17.2 kgf/c rr with all 0 pieces
i'', both of which are within the practical standard of 6.0 kg.
r/cm' and was sufficiently practical.

In the process of blowing resin-coated sand into the mold, air containing atomized petroleum solvent was applied 30 minutes, 60 minutes, 80 minutes, and 100 minutes after preparing the resin-coated sand. , 120
Minutes later, 140 minutes later.

After 160 minutes, after 180 minutes, after 200 minutes, after 220 minutes, 2
A series of the above-mentioned continuous steps such as blowing and curing of the resin-coated sand were carried out in the same manner as in Example 1, except that 125 parts each (1375 parts in total) of the solvent was added evenly to the resin-coated sand after 40 minutes. The process was carried out to produce a total of 720 camshaft core sand molds weighing 250 g. The tensile strength of the sand mold 10 minutes after manufacturing was within the range of 1O32 to 16.5 kgf/c for all 720 Ir pieces, both of which met the practical standard of 6.0 kgf'/crn'.
It was far beyond λ and was sufficiently practical.

In the process of blowing the resin FtLm sand into the mold, air containing atomized petroleum solvent was applied for 30 minutes, 60 minutes, 80 minutes, and 100 minutes after preparing the resin mm sand. After, 1
2 each after 20 minutes, 140 minutes, 160 minutes, and 180 minutes.
A series of continuous steps such as blowing the resin-coated sand and curing were carried out in the same manner as in Example 1, except that a total of 1,800 parts of the solvent was added evenly to the resin-coated sand. A total of 540 camshaft core sands of 250 g of lTlff1 were produced. Manufacture 10
The tensile strength of the sand mold after 10 minutes was within the range of 8.5 to 18.6 kgf/C for all 540 Ir pieces, far exceeding the practical standard of 6.0 kgf/crr/, and sufficient for practical use. It was a target.

Comparison 10: During the process of blowing resin-coated sand into the mold, the air was not mixed with a solvent (1), and the other points were the same as in Example 1. Child sand molds were manufactured continuously.

As a result, a practical sand mold with a tensile strength of 6.0 kgf/crn' or more after 10 minutes of manufacture was obtained at about 80 minutes from the time of manufacture of the first sand mold.

We were able to manufacture 180 pieces. However, sand molds manufactured more than 80 minutes after the initial sand mold manufacture had extremely low tensile strength and could not be put to practical use.

[Effects of the invention 1 As explained above, 1 The method of the present invention makes it possible to significantly extend the usable life of resin-coated sand, making it possible to easily and economically continuously produce large quantities of high-strength foundry sand molds. This makes it possible to do this, and its practical significance is extremely large.

Claims (1)

[Claims] (1) A portion of resin-coated sand consisting of sand and a binder solution containing a phenol resin, a polyisocyanate compound, and a solvent is introduced into a sand mold manufacturing mold, and then a curing agent is introduced into the mold. 1. A continuous method for producing foundry sand molds comprising repeating various steps, characterized in that a binder solvent is appropriately added to the remainder of the resin-coated sand.