JPS602943B2 - Method for measuring and adjusting moisture in foundry sand - 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 the moldability of foundry sand depending on the amount of water attached to it, and by measuring this, the amount of water in the foundry sand can be determined and the water content can be adjusted accordingly. The method of adjustment is well known.

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

FIG. 1 shows a conventional moisture measuring device. Four-digit intermediate troughs 4, 6 are provided below the upper trough 1 with slits 5, 7, 9 whose spacing gradually increases as they go to the right, and whose bottoms become lower as they go to the right.
, 8, and 10 are provided. Further, a slit 3 is provided in the bottom 2 of the upper trough 1 so as to be located above the intermediate trough 4. Furthermore, a lower trough 11 is located below the intermediate troughs 4, 6, 8, and 10.
are provided and supported by the main body of the upper trough 1, and phototubes 12P, 13P, 14P and floodlights 12P', 13P', for detecting the molding sand 18 falling from the slits 5, 7, 9 on the bottom side wall of the lower trough 11. Light-transmitting holes 12, 13, and 14 of 14P' (FIG. 2) are provided. The molding sand separator 1' having such a configuration is supported by an elastic support 16 equipped with a vibration device 15, and the molding sand 18 is further supplied to the molding sand separator 1' from a kneading device (not shown). A chute 17 is provided. Figure 2 shows the − dot-dashed line in Figure 1.
, is a sectional view seen from the direction of arrow A'.

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

Next, the effect will be explained.

In FIG. 1, the vibration device 15 is operated to vibrate the entire separator 1', and molding sand 18 is supplied from the kneading device (not shown) to the upper trough through the chute 17. 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 spacing between the slits 3 and does not fall from the slits 3, but instead moves to the right on the upper trough and falls from the right end of the bottom part 2. becomes. The foundry sand 18 that has fallen from the slit 3 to the intermediate trough 4 below is further transferred to the intermediate troughs 4, 6,
Move to the right in the order of 8 and 10. During this moving process, the smaller the amount of water, the more it falls into the slits 5, 7, and 9 in this order. However, when the water content exceeds a certain limit, slit 5,
The particles agglomerate to a greater extent than the distance between the slits 5, 7, and 9, and do not fall from the slits 5, 7, and 9, but move to the right and fall from the right end of the intermediate trough 10. The molding sand 18 that has fallen from the slits 5, 7, and 9 moves on the trough 11 to the right again.

The foundry sand 1 that fell from the slit 5 during this movement process
When 8 comes to the position of the hole 12, it is detected by the photocell 12. Similarly, molding sand 18 falling from slits 7 and 9 is detected by phototubes 13P and 14P in holes 13 and 14, respectively. Figure 3 shows the above photocells 12P, 13P, 14.
The actual detection results of P are shown.

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, 14P in Figure 4 are from Figures 1 to 3.
This is the phototube mentioned in the figure. 12S, 13S, 14
S is an output signal when each phototube 12P, 13P, 14P is turned on.

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

23V, 24V, 25V are each output signal 12S, 13S,
These are control valves that operate based on 14S, and the flow rate increases in order.

26 is a mud kneading device for the foundry sand 18.

27 is a control valve 23 for each output signal 12S, 13S, 14S.
This is a regulator for converting into V, 24V, and 25V operation signals.

Next, the effect will be explained.

The output signals 12S, 13S, 14S resulting from the detection of each phototube 12P, 13P, 14P are converted into operation signals 12S', 13S of the control valves 23V, 24V, 25V by the regulator 27.
', 14S'. In this way, the control valve 23V, 2
The amount of water added to the foundry sand 18 in the kneading device 26 is adjusted by opening and closing 4V and 25V. These conventional moisture measurement and moisture adjustment methods include the following three major methods:
Because of the following problems, its utility value for controlling the moisture content of ordinary foundry sand was extremely low.

First of all, regarding moisture measurement, graph 20 in Figure 3,
As shown in 21 and 22, it was not possible to provide instructions for people to estimate the actual moisture content of foundry sand as a numerical value (%).

Therefore, since it is not possible to compare the water content with the target water content, it is extremely difficult for humans to judge whether or not the amount of water added during the straining process is appropriate. In other words, it could not be used as a moisture measurement/instruction device. Second, regarding moisture control, as shown in graphs 20, 21, and 22 in Figure 3, each phototube can be turned from ON to OFF or OFF.
The point is that the time it takes to change from ON to ON is extremely short, so 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 higher the photocell 12P.
, 13P, and 14P are detected in this order. When the foundry sand falls from the slits 5, 7, and 9, although the moisture content is the same as a whole, due to uneven drilling, the influence of clumps, etc., some of the foundry sand Some molding sand may fall from the slit 5, and some molding sand may fall from the slit 7. Furthermore, even in foundry sand detected by the same phototube, for example phototube 12P, there is naturally some 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. It is an object of the present invention to provide a method for measuring and adjusting the moisture content of foundry sand that eliminates the three conventional drawbacks described above by using the measuring device shown in FIG.

The present invention will be explained based on the embodiments shown in FIGS. 5 to 7. 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, and 14P are the phototubes described in FIGS. 1 to 3.

12S, 13S, 14S are respective phototubes 12P, 13P
, 1 This is the output signal when 4P is ON.

30 is a storage/arithmetic device that performs calculations based on the input signals 12S, 13S, and 14S; 30' is an instruction control device that displays the moisture value (%) based on the input signal 30S; and 32 is an operation signal 31.
A control valve operated by S, 33 is a water supply pipe.

Reference numerals 18 and 26 are foundry sand and tumbler devices shown in FIG.

Next, the operation of the present invention will be explained. Each photocell 12P,
Output signals from 13P and 14P 12S. 13S, 14S
is shown in FIG. 3 as explained in the conventional example. Based on the combination of the output signals 12S, 13S, and 14S, that is, the combination of ON and OFF of each phototube 12P, 13P, and 14P, the moisture content is indicated as a numerical value (%).

As shown in Table 1, each photocell 12P, 1
It is assumed that the moisture value (%) corresponding to the ON/OFF combination of 3P and 14P is determined in advance.

(However, Table 1 shows only the main combinations.) The moisture values (%) in Table 1 are hereinafter referred to as set moisture values). The method for determining this set moisture value is based on various moisture values (%
) The foundry sand mixed and adjusted was actually measured using the measuring device shown in Figure 1, and each phototube 12P, corresponding to various moisture values (%),
Photographs can be taken by knowing the ON and OFF states of 13P and 14P. This set moisture value (%) and the corresponding combination of ON and OFF of each phototube are stored in the storage/arithmetic unit 30, and the graphs 20, 21 as shown in FIG.
, 22 (same as in FIG. 3)
For example, a, b, c, d...i (%) in FIG.
), conversion is performed every 0.1 seconds to replace the moisture content with a numerical value (%).

And for every 100 of this converted moisture value (%), the seventh
As shown in the figure, the average moisture values are b', c'...
Calculate e' (%)... That is, as shown by the dotted line every 0.1 seconds, one converted moisture value (%) is updated one after another, and the 100 converted moisture values (%) are always averaged to obtain the average moisture value (%). ) is calculated. Then, this average moisture value (%) is input to the instruction control device 30' as a signal 30S.
Instruct the person to file a self-prosecution. (This makes it possible to solve the first problem of the conventional method.) Next, regarding moisture adjustment, the instruction and control device 30' determines the deviation between the average moisture value (%) and the target moisture value (%). The value is determined and converted into an operation signal 31S for the control valve 32 so as to add water appropriately according to the value.

This operation signal 31S is outputted regularly every 0.1 seconds, so that the operation of the control valve 32 can reliably follow and adjust the valve opening degree. In the above, the average moisture value (%) is calculated every 0.1 seconds, but by appropriately increasing or decreasing the calculation time interval according to the operating characteristics of the control valve 32, the average moisture value (%) can be calculated accurately. It is clear that it is possible to follow the motion of

(This solves the second conventional problem.) Next, the purpose of averaging every 100 converted moisture values (%) as illustrated 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 conventional problem. As mentioned in the third problem with the conventional method, there is variation in the moisture content of the foundry sand detected by the same phototube, and in addition
(FIG. 1), some of the foundry sand may fall from the slit 5 and some from the slit 7 even though they have the same moisture content. In addition to this, considering the setting error of the set moisture value (Table 1), the converted moisture value (%) a every 0.1 seconds shown in Figure 6
, b, c...i (%) is simply the length expressed numerically, and the reliability of the numerical value (%) is extremely low. Therefore, in order to solve this problem, as illustrated above, 100
By calculating the average moisture value (%) obtained by averaging the converted moisture values (%) of 1.0 to 1.0 seconds every 0.1 seconds, it is intended to correct for variations in measurement accuracy. Since the control valve 32 shown in FIG. 5 is controlled as described above based on the average moisture value (%) determined in this way, it is possible to perform appropriate moisture addition while maintaining strict accuracy with respect to the target moisture value. becomes. Specifically expressed in numerical terms, the conventional accuracy is 0.3% to 0.5
% can be improved to ±0.1% or less. To summarize and reiterate the effects of the present invention, firstly, it has made possible to monitor the moisture value (%), which was not possible in the past, and to provide a molding sand moisture measurement and instruction device with improved indication accuracy. did.

Second, it has become possible to provide a molding sand moisture control device in which the operation of the moisture addition control section reliably follows the operation signal from the moisture measurement instruction device. Thirdly, adjust the accuracy of the moisture adjustment device from 0.3% to 0.5% to 0.
．． This is a point that can be improved to 1% or less.

[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 for converting the moisture value from the measurement results shown in FIG. 3 in the present invention, and FIG. 7 is an example diagram for calculating the average value of the converted moisture value according to the present invention. 1, 4, 6, 8, 10: trough, 3, 5, 7.9: slit, 12P, 13P, 14P: sensor, 18: foundry sand, 26: kneading device, 30: memory calculation device, 30': instruction Control device, a, b, c to -i: Converted moisture value, a', b
', c' to e': average moisture value. Nah, 2, 3, 4, 5, 5, O, 7

Claims (1)

[Claims] 1. Feed foundry sand from a kneading device to a trough provided with a plurality of slits of different widths, detect with a plurality of sensors which of the slits it has fallen from, and measure the moisture content, and based on this, In the method of measuring and adjusting the moisture content of foundry sand to adjust the amount of water added so as to maintain the target moisture value, a moisture value corresponding to the combination state of the detection operations of the plurality of sensors is set in advance, and the moisture value is set. A storage/arithmetic device that stores moisture values converts the combination of detection operations sent from the plurality of sensors into moisture values at certain fixed time intervals, and for a certain fixed number of the converted moisture values. The average value of the kneading apparatus is characterized in that the average value of the kneading apparatus is obtained at regular time intervals, and the average moisture value is inputted to the instruction control device to provide a monitorable instruction and to adjust the amount of water added in the kneading device. Method for measuring and adjusting moisture in foundry sand.