JPS58938B2 - Foundry sand moisture control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring and controlling the moisture content of foundry sand.

This type of conventional method focuses on the variation in moldability of molding sand that depends on the amount of moisture adhering to the sand, and by measuring this, the amount of moisture in the molding sand can be determined and water can be added. Moisture control methods are well known.

A conventional example will be explained below based on FIGS. 1 to 4.

FIG. 1 shows a conventional moisture measuring device.

Four intermediate troughs 4, 6 are provided below the upper trough 1 with slits 5, 7.9 whose spacing gradually increases as they move toward the right, and whose bottoms become lower as they move toward the right. 8.10 shall be established.

Further, a slit 3 at the bottom 2 of the upper trough 1 is provided so as to be located above the intermediate trough 4.

Furthermore, below the intermediate troughs 4.6, 8, and 10, there is a lower trough 1.
1 is provided and supported by the body of the upper trough 1, and detects the foundry sand 18 falling from the slits 5, 7.9 on the bottom side wall of the lower trough 11.

13P, 14P and floodlight 12P', 13P', 14P
' (Fig. 2) are provided with holes 12, 13, and 14 for transmitting light.

The foundry sand separator 1' having such a configuration is
5 and is further provided with a chute 17 for feeding the foundry sand 18 from a kneading device (not shown) to the foundry sand separation device 1'.

FIG. 2 is a cross-sectional view of the dashed-dotted line portion in FIG. 1 viewed from the direction of arrows A and R.

1 is an upper trough, 2 is a bottom of the upper trough 1, 8 is an intermediate trough, 11 is a lower trough 12, 13 and 14 are holes for light transmission, and 12P.

13P and 14P are phototubes 12P', 13P' and 14P' are projectors.

Next, the effect will be explained.

In FIG. 1, molding sand 18 is supplied from a kneading device (not shown) to the upper trough 1 through the chute 17 while the vibration device 15 is operated to vibrate the entire separator 1'.

The supplied molding sand 18 moves to the right on the upper trough 1, and most of the molding sand 18 falls from the slit 3.

However, when the moisture content exceeds a certain limit, the foundry sand 18 aggregates larger than the slit 30 interval and does not fall from the slit 3, but instead moves to the right on the upper trough 1 and falls from the right end of the bottom 2. .

Foundry sand 1 falling from slit 3 to intermediate trough 4 below
8 further moves to the right in the order of intermediate troughs 4, 6, 8, and 10.

In this moving process, the smaller the moisture content, the more the slit 5
, 7.9.

However, when the water content exceeds a certain limit, the slits 5 and 7.
The particles aggregate larger than the interval 9 and do not fall from the slits 5 and 7.9, but move to the right and fall from the right end of the intermediate trough 10.

The molding sand 18 that fell from the slits 5 and 7.9 is in the trough 1.
1 Move to the right again.

The foundry sand 1 that fell from the slit 5 during this movement process
8 comes to the position of the hole 12, it is detected by the phototube 12P.

Similarly, the molding sand 18 falling from the slit 7.9 is placed in the holes 13 and 14, respectively, to the phototube 13P.

Detected by 14P.

FIG. 3 shows the actual detection results of the phototubes 12P, 13P, and 14P.

Graphs 20, 21 and 22 are phototubes 12P, 13P, respectively.
Indicates the ON/OFF status of 14P.

FIG. 4 is a diagram showing a conventional example of a moisture adjustment method.

12P, 13P, and 14P in Figure 4 are from Figures 1 to 3.
This is the phototube mentioned in the figure.

12S. 13S and 14S are each phototube 12P, 13P, 1
This is the output signal when 4P is ON.

23, 24, and 25 are water supply pipes whose flow rates are increased in order.

23V. 24V and 25V are the respective output signals 12S and 13S.

These are control valves that operate based on 14S, and the flow rate increases in order.

26 is a kneading device for the foundry sand 18.

27 is each output signal 12S, 1.3S. 14S as control valve 2
This is a regulator for converting into 3V, 24V, and 25V operation signals.

Next, the effect will be explained.

Each photocell 12P. The respective output signals 12S, 13S, 14S resulting from the detection of 13P, 14P are generated by the regulator 27 as operation signals 12S for the control valves 23V, 24V, 25V.

Converted to 13S and 14S.

In this manner, the amount of water added to the foundry sand 18 in the kneading device 26 is adjusted by opening and closing the control valves 23V, 24V, and 25V.

These conventional moisture measurement and moisture control methods have the following four major problems, and therefore have extremely low utility for controlling the moisture content of ordinary foundry sand.

First of all, regarding moisture measurement, graph 20 in Figure 3,
As shown in 21.22, it was not possible to provide instructions for visual reading of the actual moisture content of foundry sand as a numerical percentage.

Therefore, since it is not possible to compare the moisture content with the target moisture value, it is extremely difficult for humans to judge whether or not the amount of moisture added during the kneading process is appropriate.

In other words, it could not be used as a moisture measurement/instruction device.

Second, regarding moisture control, graph 20.21 in Figure 3
, 22, from ON to OFF of each photocell,
Another problem is that the time required to change from ON to OFF is so short that the opening/closing operation of the control valve cannot follow it.

Thirdly, the following problems can also be raised regarding moisture control.

In Figure 1, the lower the moisture content of the foundry sand, the more the photocell 12P
, 13P, 14P are detected in the order of slits 5, 7, 9 . When molding sand falls from the slit 5, some molding sand may fall from the slit 5 and some from the slit 7 due to uneven kneading or the influence of clumps, even though the moisture content is the same as a whole. It is.

Furthermore, even in the molding sand detected by the same phototube, for example, the phototube 12P, there is naturally a variation in the moisture content.

This is natural since there is a limit to the number of slits.

However, in contrast, in the case of water addition in the conventional example, only a single water addition is performed when the same phototube is used for detection.

Therefore, in normal moisture management of foundry sand, it is difficult to maintain strict accuracy in moisture control with respect to the target moisture value.

Furthermore, the fourth drawback will be described below.

In Figure 1, molding sand 1 is poured onto the trough bottom 2 from a kneading device.
8 is not flowing, the detection phototubes 12P, 13P, 1
4P does not detect the foundry sand 18.

Furthermore, even if the foundry sand 18 is flowing from the kneading device, if it becomes larger than the water content limit, it will not fall from the slit 3 but will move to the right, so the phototubes 12P, 13P, and 14P will not detect the foundry sand 18.

In this way, the photocells 12P, 13P, and 14P are connected to the molding sand 18
There are two possible cases in which the above-mentioned cases are not detected.

Therefore, photocell 12P. When 13P and 14P do not detect foundry sand 18, it is not appropriate to judge that this is higher than the water content limit and control water addition accordingly, as in the case of the above two cases. It is necessary to judge which category it belongs to.

Conventionally, the molding sand 18 was spread over the trough bottom 2 in this way.
Because there was no detection device to determine whether or not water was flowing, appropriate moisture measurement and water addition control were not possible.

An object of the present invention is to provide a method for measuring and adjusting the moisture content of foundry sand that eliminates the above four conventional drawbacks by using the measuring device shown in FIG.

The present invention will be explained based on the embodiments shown in FIGS. 5 to 9.

FIG. 5 is an embodiment of the method for measuring and adjusting the moisture content of foundry sand according to the present invention.

12P, 13P. 14P is the phototube described in FIGS. 1-3.

128, 13S, 14S are phototubes 12P, 13P, respectively.
, 14P is the output signal when it is ON.

Reference numeral 30 denotes a storage/arithmetic device, such as a microcomputer, which performs arithmetic operations based on input signals 12S, 13S, and 14S.

Reference numeral 30' indicates an instruction control device that displays the moisture value (%) in response to an input signal 30S, 32 indicates a control valve operated in response to an operation signal 31S, and 33 indicates a water supply pipe.

18 and 26 are foundry sand and kneading devices shown in FIG.

Next, the operation of the present invention will be explained.

Output signal 12S from each phototube 12P, 13P, 14P
.

13S and 14S are shown in FIG. 3 as explained in the conventional example.

This combination of output signals 12S, 13S, 14S, ie, ON of each phototube 12P, 13P, 14P.

The moisture content is indicated as a numerical percentage based on the OFF combination.

As shown in Table 1, each photocell 12P, 13P,
Moisture value (%) corresponding to the combination of 14P ON and OFF
shall be sought.

(However, Table 1 shows only the main combinations.

) The moisture value (%) in Table 1 will be hereinafter referred to as the set moisture value.

The method of determining this set moisture value is to actually measure foundry sand that has been kneaded and adjusted to various moisture values (%) using the measuring device shown in Fig.
P, 14P ON.

This can be obtained by knowing the OFF state.

This set moisture value % and the corresponding ON of each photocell,
The OFF combination is stored in the storage/arithmetic device 30,
Graphs 20, 21, 22 (third
The combination of output signals 128, 138, 148 consisting of
．． Conversion is performed every second to replace the moisture content with a numerical value (%).

Then, as shown in Figure 7 for every 100 converted moisture values (%), the average moisture values a', b', c'...e
′%... is calculated.

In other words, every 0.1 seconds, one converted moisture value % is displayed as shown by the dotted line.
is updated one after another, and the average of 100 converted moisture value % is always calculated to calculate the average moisture value %.

This average moisture value % is then given as an input signal 308 to the instruction control device 30' so that it can be visually read by a person.

(This will solve the first problem of the conventional method.

) Next, regarding moisture adjustment, the instruction control device 30' calculates the deviation value between the average moisture value % and the target moisture value %,
This is converted into an operation signal 31S for the control valve 32 so as to perform appropriate water addition accordingly.

By outputting this operation signal 31S regularly every 0.1 seconds, the operation of the control valve 32 can be reliably followed and the valve opening degree can be adjusted.

Although the average moisture value % is calculated every 0.1 seconds, the operation of the control valve 32 can be accurately controlled by appropriately increasing or decreasing the calculation time interval according to the operating characteristics of the control valve 32. It is clear that it is possible to follow the

(This will solve the second conventional problem.

) Next, the purpose of averaging every 100 converted moisture values as exemplified above will be described.

This is the most important point of the present invention, as it improves the measurement instruction accuracy mentioned above and also solves the third problem of the prior art.

As mentioned in the third problem with the conventional method, there are variations in the moisture content of the foundry sand detected by the same phototube, and furthermore, the foundry sand falls from the slits 5, 7, and 9 (Fig. 1). In this case, some foundry sand may fall from slit 5 and some foundry sand may fall from slit 7 even though the water content is the same.

In addition to this, if we consider the setting error of the set moisture value (Table 1), the converted moisture value % a every 0.1 seconds as shown in Figure 6.
, b, c...j% are merely numerically expressed lengths, and the reliability of these numerical percentages is extremely low.

Therefore, in order to solve this problem, as shown in the example above, 100 converted moisture values (%) are averaged every 0.1 seconds to find the average moisture value %, thereby trying to narrow down the variation in measurement accuracy. It is something.

Since the control valve 32 shown in FIG. 5 is controlled as described above based on the average moisture value % thus obtained, it is possible to perform appropriate moisture addition while maintaining strict accuracy with respect to the target moisture value. .

Specifically expressed in numerical terms, the conventional accuracy is ±0.3% to ±0.
5% can be improved to ±0.1% or less.

Next, the fourth drawback of the conventional method (when the molding sand 18 is not flowing from the kneading device over the trough bottom 2 in FIG. 1, the phototubes 12P, 13P, and 14P do not detect the molding sand 18 The problem is that the moisture value of the foundry sand 18 has become too high to prevent it from falling from the slit 3 to the intermediate troughs 4, 6, 8° 10, and the moisture addition is adjusted accordingly. We will explain how to solve this problem.

FIG. 8 is an embodiment of the present invention related to the above.

Trough bottom 2 of a separating device 1' having the same configuration as in FIG.
A phototube 20P is provided on a support device (not shown) above the trough bottom 2 in order to determine whether or not the foundry sand 18 is flowing above from the kneading device.

The trough bottom 2 is made of a material such as Al, which has an extrusion property and serves as a light projector for the phototube 20P.

FIG. 9 is a sectional view taken along the line A-A' in FIG. 8.

Next, the above effect will be explained.

In FIG. 8, if the molding sand 18 stops flowing on the trough bottom 2 due to circumstances on the kneading device side, the phototube 20P detects that the molding sand 18 is no longer on the trough bottom 2 at the moment it stops flowing. .

Incidentally, at the time after this detection, the foundry sand 18 that was flowing on the bottom 2 of the front cloth trough still flows from the slit 3 to the intermediate trough 4,
6° 8.10 and the foundry sand 18 is falling to the trough bottom 2.
Under normal operating conditions before the phenomenon of no flow occurring above, most of the foundry sand 18 falls through the slits 5, 7 and 9 and passes through the phototubes 12P and 13P.

14P, the moisture value is visually readable based on the various detection combinations, and appropriate moisture addition control is being continued accordingly.

However, when the phototube 20P detects that the molding sand 18 has stopped flowing over the trough bottom 2, the molding sand 18 that had been flowing over the frontmost fabric trough bottom 2 flows from the slit 3 to the intermediate troughs 4, 6, and 8. Falling into °10 and photocell 12
All detections by P, 13P, and 14P are completed.

That is, it becomes impossible to obtain data that serves as the basis for displaying moisture values and adjusting and controlling moisture addition.

Therefore, in the present invention, when it is detected that the foundry sand 18 is not flowing on the trough bottom 2, a display to that effect is displayed, and at the same time as the detection, a control signal for adjusting the water addition at the time of the detection is stored in the arithmetic unit. It is stored in memory at (30 in FIG. 5).

(This is because subsequent moisture measurements cannot be made, so the latest average moisture value when 100 pieces of moisture measurement data have been collected (according to the example of the control method already described) will be determined at the time of this detection. This is because it can only be obtained by

) After the above-mentioned detection, the water addition is controlled by phototube 20P to detect that the foundry sand 18 has flowed onto the trough bottom 2 again.
This control signal stored in the storage/arithmetic unit (30 in FIG. 5) continues until the detection is detected.

In other words, as is clear from what has already been described in the section on how to solve the third drawback of the conventional method according to the present invention, the water addition control method of the present invention is to control the water addition as much as possible during kneading to achieve the target moisture value. It can be said that this is the best strategy to add moisture as close as possible.

(This is because it is not possible to obtain moisture measurement data, which is the basis for controlling the adjustment of water addition. Therefore, interrupting the adjustment control of water addition only while the foundry sand 18 is not flowing on the trough bottom 2 is difficult for the kneading equipment. It is clear that continuous operation is not a good idea in terms of target moisture management.

) To summarize and reiterate the effects of the present invention, firstly, it is possible to monitor the moisture value (c), which was not possible in the past, and also to provide a molding sand moisture measurement and instruction device with improved indication accuracy. And so.

Second, it has become possible to provide a molding sand moisture control device in which the operation of the moisture addition control section can reliably follow the operation signal from the moisture measurement instruction device.

Thirdly, the adjustment accuracy of the moisture adjustment device mentioned above has been improved to ±0 compared to the conventional one.
．． The point is that it can be improved from 3% to ±0.5% to ±0.1% or less.

Fourth, as explained in FIG. 8, the phototubes 12P and 13
If neither P nor 14P detects any foundry sand, either the foundry sand is not detected because it is not flowing from the kneading device to the separator 1', or the foundry sand is flowing to the separator 1'. The phototube 20P determines whether the water content is not detected because the water content has become so high that it does not fall through the slit 3, thereby allowing accurate water content display and adjustment control of water addition.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a conventional moisture measuring device, Fig. 2 is a cross-sectional view of the dashed-dotted line in Fig. 1, viewed from the direction of arrows A and A';
FIG. 3 is a diagram showing the measurement results by the measuring device of FIG. 1, FIG. 4 is an example of the conventional moisture adjustment method, FIG. 5 is an example of the moisture measurement and adjustment method of the present invention, and FIG. The figure is an example diagram of converting the moisture value from the measurement results of Figure 3 in the present invention, Figure 7 is an example diagram of calculating the average value of the converted moisture value according to the present invention, and Figures 8 and 9 are examples of the present invention. FIG. 1.4, 6, 8, 10 Nidraft, 3, 5, 7°9 Nisrit, 12P, 13P, 14P: Sensor, 18: Foundry sand, 20P: Detection device, 26: Kneading device.

Claims (1)

[Claims] 1. Molding sand is supplied from a crosstalk device to a trough provided with a plurality of slits of different widths, and a plurality of sensors detect which of the slits it has fallen from to measure the moisture content, and based on this, A detection device for determining whether or not the foundry sand is being supplied from the crosstalk device to the trough is provided in a foundry sand moisture control device that adjusts the amount of added water so as to maintain a target moisture value. A foundry sand moisture measuring device and regulating device, characterized in that: