JPH0436780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a quantitative supply device for molten metal.

(Conventional Example) As shown in Japanese Unexamined Patent Publication No. 55-48466, a pouring furnace using pressure control has been known, and molten metal is stored in the pouring machine body, and air pressure is applied to the molten metal through a pressure valve. A metering supply device that supplies molten metal from a tap nozzle of a pouring machine body to a pouring pot, that is, performs cutting, is also well known.

In such a device, if the air pressure is kept constant, there is a linear relationship between the cutting weight, which is the supply weight based on the above-mentioned cutting of the molten metal, and the pressurization time. The weight of the molten metal cut out in this way is detected by detecting the weight of the molten metal in the pouring pot using a weight detector consisting of a load cell, and when the weight reaches a certain value, a pressurizing valve is activated. is controlled to close the exhaust valve and open the exhaust valve to match the cut-out weight W _O set as the target.

In this case, even if you open the exhaust valve at the above point to create atmospheric pressure inside the main body, the cutting will not stop immediately, but will stop only when the molten metal level near the tap nozzle becomes low enough to reach the stopping point. do. This is called afterflow, and this afterflow time is unique to each pouring machine, and it has been empirically determined that for some models it is about 2 seconds.

In this way, it is known that the afterflow time is approximately 2 seconds, so if we calculate that even if the amount of molten metal cut out per unit time increases in the above linear relationship during the afterflow time, it is inevitable that The amount of afterflow will also be determined.

From this, the target cutting weight W _O and afterflow amount W _A are set in advance using a digital switch, and after pressurizing the air, the output of the weight detector becomes (W _O − W _A ). If the exhaust valve is opened when the exhaust valve is used, the calculated amount of WA afterflow will be obtained and the target cut-out weight W _O will be reached.

However, when using such a control method, there are the following problems.

In other words, the cutting weight dw/dt per unit time is
Although it appears to be linear and always maintains a constant value, in reality it has a property that changes over time due to various factors. For example, the flow rate may fluctuate due to slag that does not stick in the intermediate passage leading to the tap nozzle,
The nozzle diameter of the tap nozzle itself changes due to the adhesion of slag, resulting in fluctuations in the cutting speed, or the amount of molten metal inside the pouring machine changes, resulting in fluctuations in the cutting speed, resulting in the afterflow amount. Of course, this will also change.

Therefore, the cutting weight W _O , which is the final target,
Variations occur, and this is where countermeasures are taken.

(Object of the Invention) The present invention was made to eliminate the above-mentioned conventional drawbacks, and aims to always accurately obtain the target final amount of molten metal cut out regardless of fluctuations in the cut-out speed.

(Structure of the Invention) FIG. 1 is an overall block diagram for clearly showing the structure of the invention.

A device that supplies a fixed amount of molten metal for casting, which includes a pressurized chamber that accommodates the molten metal and on which air pressure can be applied, and a tap nozzle that raises the molten metal from the pressurized surface by applying pressure and taps out the metal. a pressurizing valve capable of stopping the supply of pressurized air to the pressurizing chamber; an exhaust valve capable of communicating or shutting off the pressurizing chamber and the atmosphere; and a tapping nozzle for pouring molten metal into a mold. A pouring pot that receives molten metal discharged from the pouring pot, a weight detector that detects the weight of the molten metal in the pouring pot, and a detection value of the weight detector when the pressurizing valve is opened and the metal is poured into the pouring pot. Calculate the rate of increase per unit time and set in advance as the time from the time when the pressurizing valve is closed and the exhaust valve is opened to the time when cutting, which is the supply of molten metal from the tapping nozzle to the pouring pot, is completed. Based on the predetermined time and the increase rate, the cut-out weight, which is the supply weight based on the cut-out after the elapse of the predetermined time from the time of detection by the weight detector, is cut out for a predetermined time at the increase rate. a prediction means for predicting based on the assumption that the predicted value by the prediction means matches the final cutting weight set as a target, a comparison means for outputting a coincidence signal, and a pressurizing valve that operates in response to the coincidence signal. A weight detector 13 detects the changing cutting weight in real time and calculates the increase rate, and also calculates the increase rate and a predetermined time (afterflow time). ), the cutout weight is always predicted after a predetermined time after detection,
The time when the prediction reaches the final cutting weight set as the target is set as the afterflow start time, and the pressurizing valve 4 is closed and the exhaust valve 5 is opened.
The target final cutting weight is accurately obtained as set.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In Figure 2, 1 is the main body of the pouring machine, and the pressurizing chamber 2
and a tapping nozzle 3, a pressurizing valve 4 that pressurizes the pressurizing chamber 2, and an exhaust valve 5 that communicates or blocks the pressurizing chamber 2 with the atmosphere.

The molten metal 6 is stored in the pouring machine body 1, and air pressure P is applied to the pressurizing surface 7 due to the action of the pressurizing valve 4.
acts. This air pressure P acts through the intermediate passage 9 and discharges (cuts out) the molten metal 6 from the tap nozzle 3 of the tap tap 9.

10 is a weir protruding from the bottom of the tap 9;
When the air pressure P is released and the level of the molten metal 6 in the tapping gutter 9 drops to the weir 10, the amount to be cut out is finally regulated. Reference numeral 11 denotes a pouring pot that receives the molten metal 6 discharged from the tapping nozzle 3 for pouring the molten metal 6 into the mold 12, and a weight detector 13 consisting of a load cell is installed at the bottom of the pot. The analog signal from this weight detector 13 is A/D converted by an A/D converter,
Furthermore, significant pulsations in the signal are removed by passing it through an integrating circuit. The thus stabilized signal is read by a microcomputer at regular intervals, and the increase rate (molten metal cutting speed) dw/dt per unit time is calculated here. As shown in Figure 3, this dw/dt is (W ₂ - W ₁ )/(t ₂ - _{t 1} )=
Corresponds to ΔW/Δt (Kg/sec).

The time setting digital switch connected to the microcomputer is a means for predicting the cut weight after a predetermined time period shown in FIG. The time from when the air pressure P is released by closing the exhaust valve 5 and releasing the air pressure P until the actual cutting is completed is determined depending on the model, and the predetermined time is set to, for example, 2 seconds. As a result, the weight W to be cut out two seconds after detection as shown in FIG. 3 is predicted at regular intervals.

The predicted value thus predicted is the sum of the detected value W ₂ by the weight detector 13 in FIG. 2 and the predicted increase value dw/dt×2 for 2 seconds. Also,
The digital switch for setting the cut-out weight is used to set the target final cut-out weight W _O as shown in Fig. 3. With this setting, when the predicted value W matches W _O , the cut-out weight A matching signal is sent from the microcomputer in Figure 2 to the drive circuit, and upon receiving the matching signal, the drive circuit closes the pressurizing valve 4 and opens the exhaust valve 5, thereby causing the inside of the pressurizing chamber 2 to become large. Afterflow starts due to atmospheric pressure. By performing this afterflow at the set time while maintaining the above increase rate dw/dt, the target cutting weight W _O can be obtained as set, and this can be obtained without being affected by slag adhesion or other factors. It is something.

In addition, the correction memory is the final cutting weight that was set.
Difference Ws between W _O and actual final cutting weight W (= W _O −
W), and the correction digital switch is used to set the correction factor α. As a result, the cut weight is corrected at the next cutting time by the weight dWs obtained by multiplying the above difference Ws by the correction factor α. In this case, the correction factor α is 0 to 100.
It can be set up to %, for example, 100% here is
This means a case where correction is made based on the prediction that an error Ws will occur from the previous cutout. In this case, there is a method of correcting afterflow time instead of weight correction as described above. When correcting the afterflow time in this way, the digital switch for correction is set so that correction can be performed using the minimum unit of correction time, for example, 0.1.

A flowchart for executing the above control is shown in FIG. Note that P ₁ to _{P 9} in the figure indicate each step of the flowchart.

First, in _P1 , check whether a pressurization start signal has been issued, and if a start signal has been issued, read the final cutting weight and the setting values of each digital switch in _P2 , and in _P3 , Check that the load cell signal has started rising. Next, at _P4 , sampling is performed based on weight detection signals at different times by the weight detector 13, and the increase rate dw/dt is calculated at fixed time intervals based on the sampling.
At _P5 , a predicted value is calculated based on the increase rate dw/dt and the predetermined time, and it is checked whether the predicted value matches the final cut weight (set value).

If they match, an exhaust signal is output at P ₆ , and the second
The pressurizing valve 4 is controlled to be closed and the exhaust valve 5 is controlled to be open through the drive circuit shown in the figure. At P ₇ , it is determined whether the afterflow has ended or not, and if so,
At _P8 , the actual value (actual pouring amount) W of the final cutting weight is compared with the set value W _O , and it is checked whether the difference is within an acceptable level. Therefore, in P ₉ , read the actual pouring amount using the correction memory,
If it is necessary to correct the set value of the final cutting weight in order to change the actual amount of molten metal poured next time, this will be done by changing the setting of the correction digital switch. Note that the pressurizing valve 4 and the exhaust valve 5 can be configured as three-way valves.

(Effects of the Invention) As explained above, according to the present invention, the weight detector detects the changing cutting weight in real time and calculates the increase rate, and also calculates the increase rate and the predetermined time (afterflow time). Based on this, the weight to be cut out after a predetermined time after detection is always predicted, and when the predicted value reaches the final cutout weight set as the target, the pressurizing valve is closed and the exhaust valve is opened. By doing so, the target final amount of molten metal to be cut out can always be accurately obtained regardless of fluctuations in the cutting speed.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of this invention, Fig. 2 is a block diagram showing an embodiment of this invention, and Fig. 3 is a method of calculating the increase rate at the time of weight detection and the cut-out weight after a predetermined time has elapsed. FIG. 4 is a flowchart showing the predicted values of . 1... Main body of pouring machine, 2... Pressurizing chamber, 3... Tapping nozzle, 4... Pressurizing valve, 5... Exhaust valve, 6... Molten metal, 11... Pouring pot, 12... Mold ,1
3... Weight detector.

Claims (1)

[Scope of Claims] 1. A device for supplying molten metal for casting in fixed amounts at a time, comprising: a pressurizing chamber where air pressure can be applied to the upper part of the molten metal; The main body of the pouring machine has a tapping nozzle that raises and dispenses hot water, a pressurizing valve that can stop the supply of pressurized air to the pressurizing chamber, an exhaust valve that can communicate or shut off the pressurizing chamber and the atmosphere, and a metal mold in the mold. A pouring pot that receives the molten metal discharged from the tap nozzle for pouring, a weight detector that detects the weight of the molten metal in the pouring pot, and a weight detector that detects the weight of the molten metal in the pouring pot. Calculate the rate of increase per unit time of the value detected by the weight detector, and from the time when the pressurizing valve is closed and the exhaust valve is opened until the time when cutting, which is the supply of molten metal from the tapping nozzle to the pouring pot, is completed. Based on a predetermined time set in advance as the time of a prediction means for predicting on the assumption that the weight has been cut out for a predetermined period of time; a comparison means for outputting a coincidence signal when the predicted value by the prediction means matches the final cut weight set as a target; and a coincidence signal. A fixed-quantity supply device for molten metal, comprising: a drive circuit which is activated in response to a pressure valve to close a pressurizing valve and open an exhaust valve;