JPS6096347A - Method and device for forming casting mold - Google Patents

Abstract

PURPOSE:To part a pattern right after molding and to improve the efficiency of forming a casting mold by spraying the system sand formed by kneading refractory particles of a high temp. with a binder and hardener toward the surface of the pattern and solidifying quickly said sand. CONSTITUTION:Recovered zircon sand is charged into a temp. regulator 5 of a spray molding device and after the sand temp. is regulated with a heater 6, the sand is supplied via a flow rate control mechanism 7 and a shutter gate 8 to a sand mill 9. A binder and hardener are then added from nozzles 10, 11 to the sand and are instantaneously kneaded therewith. The mixed sand is admitted via a chute 12 to a booster 13. Hot wind is blown from the booster 13 to inject the sand into an acceleration chamber 15. A blast hose 16 is connected to the chamber 15. A molding flask 18 is installed on a molding board 17 and a pattern 19 and runner 20 are disposed thereon. After a facing sand layer 21 is molded by a spray molding device, backing sand 22 is sprayed and molded then the sand is immediately solidified. The drag is then upset and a molding flask 18' is installed. A pattern 19' and sprue 20' are installed and similarly the sand is molded. The mold is immediately parted and the casting mold is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold making method and an apparatus therefor, and more particularly to a mold making method capable of rapidly hardening a mold and an apparatus suitable therefor.

When manufacturing cast steel products with a casting weight of 1 ton or less,
Molds are made using borax as the refractory particles, but this method uses a molding sand blowing molding device (Japanese Patent Application No. 57-067470) developed by the applicants, which significantly reduces the number of man-hours required for sand filling. Adopts a spray molding process that reduces
In the case of self-hardening molds, even in the conventional hand molding and spray molding methods, molds are usually made using kneaded sand that has a pot life of 30 minutes or more and takes into account the blending ratio of binders and hardeners. . In this case, the molded model can be released from the mold after one hour at the earliest.
It takes several hours at most, and the rotation and molding efficiency of the model is extremely poor.

On the other hand, when manufacturing cast steel products with a casting weight of 1 ton or more, since scorching occurs on the casting surface, a sand layer with high refractory properties such as zircon sand or chromite sand is used instead of borax. The method has already been proposed in Japanese Patent Application No. 56-170788.

In this method, as shown in Figures 1 and 2, a wire mesh 2 such as expander metal or hexagonal wire mesh is stretched over the model surface 1, and pillars 4 corresponding to the sand layer thickness 3 are installed on the wire mesh according to the model dimensions. ,
A predetermined surface sand layer is formed by taking out several to several tens of sand particles and using a spray molding device.

In this case as well, since ordinary binders and curing agents with long pot life are used, the rotation of the model and the molding efficiency are poor.

The present invention has the following features: (1) rapid mold hardening using kneaded sand made by kneading high-temperature refractory particles, a binder, and a hardening agent; (2) a spray molding device (Japanese Patent Application No. 57-067470) This was done for the purpose of installing a temperature regulator in a sandbox (No. 1) and spraying high-temperature sand into the mold.

That is, the present invention provides a mold making method characterized in that: (1) kneaded sand prepared by kneading high-temperature refractory particles with a binder and a hardening agent is sprayed onto the surface of the model to rapidly solidify the mold and form the mold; (2) a crosstalk machine equipped with a temperature regulator for refractory particles, a binder injection nozzle and a hardening agent injection nozzle, a booster disposed downstream of the discharge port of the crosstalk machine, and a connection to the booster; The present invention relates to a spray molding device characterized by a plastic hose and a spray molding device.

The present invention can be applied to casting parts in general.

Appropriate spraying conditions in the present invention are based on the basic test results described below: 0 temperature is within the range of 70 to 90 degrees Celsius, the amount of binder added is 0.5 to 0.8 weight titLi6/to sand, and the amount of hardener added. It has been confirmed that it is desirable to set the amount of binder to 20 to 30% by weight/binder.

It should be noted that if the binder is less than 0.5 weight factor, the curing speed will be slow, depending on the amount of curing agent added, and if it is more than 0.8 weight factor, the curing speed will be further accelerated. It is unfavorable from the economic point of view (binder cost). In addition, the hardening agent is 20
If it is less than 40% by weight, the curing speed will be slow, depending on the amount of binder added, and if it is more than 40% by weight, the curing speed will be further accelerated, but this is not preferable from an economic point of view. 0 more
It is preferable to select a temperature as low as possible in view of the deformation and durability of the model (wooden pattern).

Moreover, the refractory particles in the present invention are borax.

Zircon sand, chromite sand, etc. are used, the binder is furan-based, phenol-based, phenol/furan-based resin, etc., and the curing agent is xylene sulfonic acid-based.

Para-toluenesulfonic acid type, benzenesulfonic acid type, and phosphoric acid type can be used.

FIG. 3 is a diagram showing an embodiment of the apparatus of the present invention.1 In FIG. 3, the recovered borax or zircon sand passes through a service tank (not shown), etc.
Pour into temperature regulator 5. This heater 6 may be configured to supply a heating medium into a tube provided with a large number of fins, for example. The temperature of the collected borax or zircon sand varies depending on the time of collection, the size of the cast product, etc., so it is controlled to a predetermined temperature by a zero temperature regulator 6. 50-100 at heater 6
Can be adjusted to ℃.

Borax or zircon sand whose temperature has been adjusted to zero is continuously and quantitatively supplied to the crosstalk machine 9 via the flow rate control mechanism 7 and the shutter gate 8 which can be opened and closed.

The mixer 9 is a multi-blade type high-speed rotation type, and the binder injection nozzle 1
0. Hardening agent injection nozzle 11. The binder and curing agent injected and added from the borax or zircon sand are instantaneously kneaded with the borax or zircon sand, and are passed through the chute 12 from the discharge port of the mixer 9 to the booster 1.
5. This booster 13 is configured to inject compressed air supplied through a supply vibrator 14 connected to a compressed air supply source (not shown) into a funnel-shaped acceleration chamber 15. A flexible plastic hose 16 is connected to the lower end of the acceleration chamber 15.

Since compressed air blown from the booster 13 described above causes a drop in the temperature of the kneaded sand, it is desirable to use heated air.

It takes 3 to 4 seconds to mix fire-resistant particles, binder, and hardener with this device, discharge them, accelerate them, and spray them. Rapid hardening progresses.

Next, a basic test conducted to understand the rapid hardening conditions of the mold in the present invention will be explained.

Basic test material (1) Fire-resistant particles: Silica sand (A, F, 135 B), zircon sand (A, F,
5110) (2) Binder: Phenol-furan resin (Koreishi Jizai Kogyo Co., Ltd., mounting product name H1100F) (0.3 to 0.8% by weight/based on sand) (3) Hardening agent: Benzene Sulfonic acid (Gallstone Equipment Industry Kensan product name PB -
20) (10 to 40% by weight/to binder) Spray molding conditions (1) Apparatus: ■ The apparatus shown in FIG. 6 was used.

■ Plast hose; 52mmφX6m ■ Amount of sand coming out i
5tOn/Hr (in case of silica sand); 1.5tO/Hr
(In the case of zircon sand) ■ Sand temperature: 50 to 100°C ■ Injection speed ratio of mixed sand (injection speed of mixed sand divided by the limit speed at which pulsation occurs when mixed sand is transported through the plasto hose) ; S, O (for silica sand) 60 (for zircon sand) (2) Model (wooden pattern), others: ■ Model (for both borax sand and zircon sand); flat plate model (250
mm x 250 mm x 50 mmt), but this model had perpendicular slits made at 50 mm intervals in order to collect anti-pressure test pieces.

■ Spraying angle: Spraying was carried out at an angle of 90° (vertical) to the model surface.

■ Spraying distance: 1 m Test results After carrying out a spraying test by varying the amounts of binder and curing agent added and the zero temperature, anti-pressure test pieces were taken and subjected to the test, and the test results are shown in Table 1. In addition, in this test, sampling was performed 5 minutes after molding, and an anti-pressure test was conducted.The evaluation of this test was that if the anti-pressure of the mold was 20 klil/- or more, there would be no problem with mold release. Based on numerical values.

Table 1 Evaluation test results based on resisting pressure (results for silica sand and zircon sand) (1) Weight 0 inch seconds (2) Weight - 11%/to binder × Resistant pressure 20 or less ○ Resistant pressure 20 kg/cd or more As a result of the above, the proper spraying condition is that the amount of binder added is 0.5.
, 0.8 weight %/to sand, curing agent 20 to 30 weight %/to binder, temperature range from 0 to 70 to 90°C. However, as shown in Table 1, proper spraying conditions are recognized under conditions other than the above. It was also confirmed that a 50 mm thick layer of zircon sand could be formed under these appropriate spraying conditions.

As seen in this result, refractory particles (silica sand).

It has become clear that if the temperature of the zircon sand (zircon sand) is raised to zero, the curing rate increases significantly, so the pot life becomes almost zero, and a rapidly hardening mold can be obtained.

Examples of molding test molds conducted to examine the validity of the appropriate spraying conditions obtained in these basic tests and examples of casting tests using the molds obtained are shown below.

Example test conditions (1) Fire-resistant particles: ■ Skin sand: Recovered zircon sand (A, F, 83B) ■ Back sand: Recovered silica sand (A, F, S 110) (2) Binder: Phenol/furan resin (Gallstone Equipment Co., Ltd. (A) Surface product name: HPloooF) (0.5% by weight/based on sand) (3) Hardening agent: Benzene sulfonic acid (Gallstone Materials Industry Jingken product name pB-2o,) (20% by weight/based on sand) Binder) (4) Shot molding device, ① The device shown in FIG. 3 was used.

■Plast hose 132mmφ×6m■ Amount of sand produced;
5tOn/H (for crushed sand) 1.5tO boat/H (for zircon sand) ■ Sand temperature: 70℃ ■ Injection speed ratio: S, O (for crushed sand) 3.0 (for zircon sand) (5 ) Prototype model: Square model with a product weight of approximately 2 tons (1000mm x 1000IIIIII x 250+
11111) was used.

(6) Spraying distance = 05~1.0 m (7) Spraying angle: 45~90' As shown in Figure 4, the lower mold for the molding test is a casting flask 18 placed on a surface plate 17, and a model 19 placed inside the frame. , 2o hot water channel was installed.

In the spray molding equipment, recovered zircon sand was put into the trench temperature regulator 5, and the sand temperature was adjusted to 90°C using the heater 6 (in order to prevent the sand temperature from decreasing during spraying, the sand temperature was increased by 920°C from the target temperature). ), and hot air of about 1°C was also blown from booster 13.

After molding the skin sand with zircon sand, crushed sand was used as the backing sand, but molding was carried out in the same manner as above.

Under the above circumstances, using the spray molding apparatus of the present invention, after molding the skin layer 21 of zircon sand to a thickness of about 20 mm on the lower mold, the back sand 17 was successively sprayed and molded, but after about 5 minutes of molding. It had solidified, and the lower mold was inverted.

After reversing, as shown in Fig. 5, install the casting flask 18' on top, and place the upper model 19' at the same position as the lower model 19 and the runner 2o.
, a sprue 20' is installed.

After that, molding was carried out in the same manner as for the lower model 19, and solidification was completed after about 5 minutes, so the upper and lower models 19' were molded immediately.
, 19 was released from the mold, and a test mold was completed.

2. Casting test Using the test mold obtained above, cast steel (So 46
) casting test (casting test 1540℃, mold drying temperature approx. 8
As a result, there were no casting defects such as gas defects on the casting surface, and a high-quality cast product could be manufactured.

As is clear from the above results, compared to normal mold making methods (such as manual molding methods), the present invention can reduce the pot life of the mixed sand to almost zero by increasing the sand temperature. Because it can, it has the following effects and effects.

(1) Since the mold can be released immediately after molding, the rotation rate of the model is increased and the molding efficiency is significantly increased.

(2) Binder and curing agent can be saved. For example, in the method of the present invention, the binder is 0.5% and the hardening agent is 20%, whereas in the conventional method, the binder is 1.0% and the hardening agent is 30%.

(3) The molding time can be significantly reduced.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams for explaining a model used in the conventional mold manufacturing method, Figure 6 is a front view showing an example of the apparatus of the present invention, and Figures 4 and 5 are views of the mold made by the present invention. It is a longitudinal cross-sectional view showing an example. 5...Sand temperature regulator, 9...Kneading machine, 10...Binder injection nozzle, 11...Hardening agent injection nozzle, 13...Booster, 16...Plast hose. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (2)

[Claims] (1) A mold making method characterized by spraying kneaded sand prepared by kneading high-temperature refractory particles with a binder and a hardening agent onto the surface of the model, rapidly solidifying the mold, and then forming the mold. (2) A kneading machine equipped with a temperature regulator for refractory particles, a binder injection nozzle and a hardening agent injection nozzle, a booster disposed downstream of the discharge port of the kneading machine, and a A spray molding device comprising a plastic hose.