JP3255347B2 - C / B value control system for kneading sand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for controlling the C / B value of kneaded sand by kneading collected green sand until it reaches a target compactability (hereinafter referred to as C / B value).

[0002]

2. Description of the Related Art Conventionally, green sand is kneaded by a kneading machine, and the kneaded sand reaching a target C / B value is discharged, conveyed by a belt conveyor, a bucket conveyor, and the like, and then applied to an aerator to supply sand to a molding machine. Supplied to the hopper,
The sand is supplied from a sand supply hopper to a mold making machine to mold the mold. However, as described above, even if a mold is molded and cast using sand having a constant C / B value of the kneaded sand discharged from the kneader, casting defects due to insufficient filling of the sand in the mold and sanding of the cast product are caused even when casting is performed. There were problems such as casting defects and kneading sand adhering to the mold making machine to cause mechanical trouble. .

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and causes problems such as insufficient filling of sand in a molding mold, defects of sand in a casting, and adhesion of kneaded sand to a molding machine. It is an object of the present invention to provide a kneaded sand C / B value control system capable of obtaining stable kneaded sand. The inventor of the present invention examined how to change the sand characteristics (particularly the C / B value) by the time the kneaded sand kneaded and adjusted by the kneading machine was introduced into the mold making machine due to the problems of the prior art. As a result of investigations at the equipment, it was found that the C / B value of the kneaded sand at the time of discharge from the kneader tends to decrease at the time of being introduced into the mold making machine, and that the variation width of the C / B value is not constant. Was.

It has been speculated that the tendency of the C / B value to fall is due to the fact that the kneaded sand is discharged, conveyed for a long distance, and subjected to an aerator or the like. It was a situation where the cause of the irregular width could not be grasped. Here, the inventor repeatedly conducted experimental tests to investigate the cause of the above-mentioned inconsistency in the variation width of the C / B value. As a result, the sand temperature at the time of sand kneading by the kneading machine was changed to the kneading sand at the time of sand injection into the mold making machine. It was found that the higher the sand temperature during kneading, the larger the C / B value variation at the mold making machine position.

[0005]

Means for Solving the Problems In order to achieve the above object, a C / B value control system for kneaded sand according to the present invention comprises mixing water by adding water to the recovered green sand and the added binder. A part of the kneading sand is sampled while measuring the C / B value of the kneading sand, and the kneading sand is repeated by repeating the addition of water, kneading and C / B value measurement until a preset target C / B value is reached. In the C / B value control system for the kneaded sand to be discharged, a program for selectively changing the target C / B value according to the sand temperature of the sampled kneaded sand is added.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. In FIG. 1, a part of the kneading sand during kneading is sampled in a kneader 1 to obtain a sand temperature, C /
Automatic sand property measuring device 2 for measuring sand properties such as B value and moisture
The sand property automatic measuring device 2 is connected to a control microcomputer 3 which inputs data such as the amount of water, the amount of sand and the temperature of the recovered sand to be charged into the kneading machine 1 from a measuring device (not shown). It is electrically connected. The control microcomputer 3 is electrically connected to a control device 4 for controlling the addition of water to the kneading machine 1 and outputting a sand characteristic measurement command signal to the automatic sand characteristic measuring device 2.

[0007] In the control microcomputer 3, the above-mentioned structure is added to the recovered sand based on data such as the amount of water, the amount of sand, and the temperature of the recovered sand to be fed into the kneader 1. A command to add the binder and water is output to the control device 4, and the binder and water are supplied to the kneading machine 1 into which the recovered sand has been charged, and kneading is started. Sand kneading progresses and a part of the kneading sand is sampled to automatically measure sand characteristics 2
, The sand characteristics are measured, and the target C / B value of the kneaded sand is selected according to the sand temperature at that time. As an example, when the sand temperature of the kneading sand is 20 ° C., the target C / B value is 44%, and when the sand temperature is 21 to 25 ° C., the target C / B value is 46%, and the sand temperature is 26 to 30 ° C. In this case, the target C / B value is selected to be 48%, and when the sand temperature is 31 ° C. or higher, the target C / B value is selected to be 50%. Based on the difference between the target C / B value selected in this way and the C / B value measured by the automatic sand characteristic measuring device 2, a water addition command is issued from the control microcomputer 3 to the control device 4, Water addition, kneading and C / B value measurement are repeated, and the C / B value of the kneaded sand is selected as the target C / B.
When reaching the value, the kneading sand is discharged. When the kneaded sand discharged in this way reaches the mold making machine, those having a high sand temperature at the time of kneading have a large variation range of the C / B value, and conversely, those having a low sand temperature have a C / B. The variation width of the B value is reduced, and almost entirely constant (standard deviation 1.
The C / B value of 4) (for example, 40%) is obtained, and the molding is performed.

[0008]

According to the present invention, as apparent from the above description, the target C / B is obtained by adding water to the recovered sand and the binder.
In the C / B value control system for kneading sand, which controls kneading until the value reaches the target C / B value,
Since a program is added in which the B value is selectively changed according to the sand temperature of the sampled kneading sand, the kneading sand kneaded by the kneading machine has a substantially constant C / B value at the position of the molding machine. It is effective in solving casting defects and other problems due to the change in sand characteristics of the kneading sand.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a C / B value control system for kneaded sand.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Kneader 2 Sand property automatic measuring device 3 Control microcomputer 4 Control device

Claims (1)

(57) [Claims] 1. A method for measuring the C / B value of a kneaded sand by sampling a portion of the kneaded sand while mixing and kneading water by adding water to the collected green sand and the added binder, and setting a predetermined target. In a C / B value control system for kneaded sand, which discharges kneaded sand by repeating addition of water, kneading and C / B value measurement until the C / B value is reached, the target C / B value is calculated based on the sampled kneaded sand. C / B value control system for kneaded sand, characterized by adding a program which is selectively changed according to the sand temperature