JPH07227668A - Method for controlling automatic pour of molten metal - Google Patents

Abstract

PURPOSE:To improve the followup ability of molten metal pouring to a teaching pattern and to obtain a casting product having high quality by setting four control ranges based on ladle wt. measured data and changing a successive control method by the variation of the measured weighing value. CONSTITUTION:At the time of teaching a pouring velocity pattern diagram, aimed pouring wt. and aimed pouring time pouring the molten metal in a mold, the pouring wt. pattern diagram 30 to pouring passed time is calculated from the pouring velocity pattern diagram, and four control ranges are set based on the ladle wt. measured data. In the first control range just after starting the tapping of the molten metal, the ladle 1 is tilted by the decided initial stage turning velocity. In the second control range, complex control transited from the initial stage turning to a feedback control is executed. In the third control range, the feedback control using the calculated pouring wt. pattern diagram 30 as a control aim is executed. In the fourth control range, a ladle 1 is turned over at the decided turning velocity Vf. By this method, the molten metal wt. We is flowed out from the ladle 1 in the prescribed time to obtain almost the aimed molten metal pouring wt. Wt.

Description

Detailed Description of the Invention

[0001]

This invention relates to a control method for automatically injecting molten metal into a mold by tilting a ladle.

[0002]

2. Description of the Related Art Various techniques have already been disclosed as control methods for automatically pouring molten metal into a mold. For example, in Japanese Patent Laid-Open No. 62-57758, the variation ratio of the surface area of the molten metal in the ladle when the ladle is tilted in advance from the geometrical shape of the ladle is stored and stored in accordance with the variation ratio. It has been shown that the tilt angle of the ladle is changed to control the outflow amount of the molten metal from the ladle to be constant. Japanese Patent Application Laid-Open No. 4-46665 discloses a method of controlling the tilting angle of the ladle by calculating the pouring speed from the measured value of the weight by means for measuring the total weight of the ladle containing the molten metal. ing.

[0003]

However, when attempting to automatically pour the molten metal into the mold in the desired pouring pattern, the molten metal surface area is calculated from the tilting angle value from the geometrical shape of the ladle, and the molten metal is calculated. In the method of calculating the molten metal head at the outlet from the weight and calculating the pouring speed, the surface area of the molten metal changes every time the shape of the ladle is changed depending on the construction method of the refractory material and the deformation depending on the usage conditions. Therefore, it does not always equal the amount of hot water that flows out. That is, it is difficult to control in a desired pouring pattern by controlling only the fluctuation of the molten metal surface area in the ladle. With the control method that feeds back the tapping weight to the pouring speed, the difference between the target pouring pattern and the measured tapping weight immediately after the start of tapping is small, so the deviation that should be fed back is small and the target pouring speed cannot be obtained. , Tend to deviate from the target pattern. Even if the feedback integral term is considered, it takes time for the integral term to produce an effect, and it is difficult to follow the pouring pattern from the initial point within the target time. It is an object of the present invention to provide an automatic pouring method capable of pouring a desired pouring pattern.

[0004]

According to the present invention, in an automatic pouring device having a means for measuring the weight of a ladle containing molten metal in a ladle, a mold is poured in a speed control of a ladle tilting drive device. When the pouring speed pattern diagram for pouring, the target pouring weight and the target pouring time are taught, the pouring weight pattern diagram for the pouring elapsed time is calculated from the pouring speed pattern diagram, and the ladle weight measurement data is calculated. Based on, set four control areas,
Immediately after tapping starts, the ladle is tilted at the determined initial rotation speed in the first control area, and in the second control area, the composite control is performed in which transition from initial rotation to feedback control is performed.
In the control area, feedback control is performed with the calculated pouring weight pattern diagram as a control target, and in the fourth control area, the ladle is inverted at a predetermined rotation speed. There is also a method of setting a new molten metal weight pattern diagram having a certain offset value to the calculated molten metal weight pattern diagram in the third control area and performing feedback control with this set as a control target. Furthermore, when the upper and lower limit positions of the molten metal in the sprue cup are detected, and when molten metal comes out of this range, the predetermined control at this point is temporarily suspended and the ladle is tilted so that the molten metal returns to within the range. After returning to within the range, the predetermined control is continued again.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, a case is shown in which a new pouring weight pattern diagram having a certain offset value is set in the calculated pouring weight pattern diagram, and feedback control is performed with this set as a control target.

FIG. 1 shows a schematic view of an automatic pouring apparatus for carrying out the present invention. In FIG. 1, 1 is a tiltable ladle for storing molten metal, 2 is a sprue cup provided in a mold 10, 3
Is a servo motor for tilting the ladle 1, 4 is a load cell for measuring the weight of the portion including the ladle 1 and the servo motor 3, 6
Is a control panel containing a CPU 11 and the like, 7 is a joystick for manually tilting the ladle, and 8 is a tap hole sensor for detecting tapping from the ladle 1.

FIG. 2 shows the system configuration of the apparatus shown in FIG. The CPU 11 in the control panel 6 takes in the values of the load cell 4, the encoder 5 of the servomotor 3 and the contents of communication with the sequencer 12, calculates the tilting speed of the ladle 1, and outputs the command voltage to the servomotor amplifier 13. Output. The sequencer 12 receives signals from the tap hole sensor 8, the tapping sensor 9, the molten metal upper limit sensor 15, the molten metal lower limit sensor 16 and the peripheral switch 14, and the communication content from the CPU 11, and controls the automatic pouring device. . 20 is CR
Reference numerals T and 17 denote a mouse and 18 a keyboard, which constitute a teaching means for interactively teaching the pouring speed pattern diagram. Reference numeral 19 is a storage device.

Next, the actual control process will be described. In the pouring pattern creating step 21 of FIG. 6, the mouse 17 and C
The RT 20 and the teaching screen shown in FIG. 3 are used interactively to teach a desired pouring speed pattern. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the pouring speed, which is the weight of pouring per unit time. P1 and P which are points to teach
2, P3, P4 are designated with the mouse. In the total area calculation step 22 of FIG. 6, the total area A of the shaded area is calculated from the teaching screen shown in FIG.

Next, the target pouring weight Wt and the target pouring time T
m, the weight of molten metal We flowing out when the ladle 1 is turned over, and the time Te required for turning off the molten metal are input and taught from the keyboard 18. We and Te are empirical values according to the target ladle shape and pouring weight. This teaching operation is performed for each item to be cast in the mold 10 and stored in the storage device 19.

The area A shown in FIG. 3 is obtained by subtracting the molten metal We flowing out when the ladle is turned over from the target molten metal weight Wt to be poured into the mold 10 in one frame.
-We) is the target pouring control weight, and Mx = (Wt-W
e) / A as a coefficient for converting the area into the weight of the molten metal, C
Calculation is performed by PU11. Similarly, (Tm-Te) is the target pouring control time, and the length of the horizontal axis on the teaching screen is L.
Then, Tx = (Tm-Te) / L is set as a coefficient for converting the time into the time on the teaching screen.
Calculate with PU11.

In the cumulative area calculation step 25 in FIG. 6, from the pouring start time to the sampling time (for example, 10 msec), from the pouring speed pattern diagram on the teaching screen shown in FIG. The cumulative area is calculated, and in the pouring weight calculation step 26 in FIG. 6, the pouring weight is calculated using the conversion factor Mx, and (Tm-
The pouring weight pattern diagram 30 during Te) is calculated. An example of this pouring weight pattern diagram 30 is shown in FIG. 4, which is the desired pouring pattern. This diagram shows that as the diagram descends, the pouring weight increases from zero.

However, the pouring weight pattern diagram 30 of FIG.
If feedback is performed with the control target set as above, there is a problem in followability as described in the problem to be solved by the invention. In the present invention, the entire pouring range is divided into four control regions shown in FIG. 7, and each has a separate control method.
That is, from the initial rotation speed region from the start of pouring to time Tb, the composite control region for smoothly transitioning to the feedback control from time Tb to Tc, the feedback control region from time Tc to Td, and the ladle inversion region after Td. Become. The control contents of each area will be described below.

The initial constant rotation speed region is a region where the ladle continues to tilt at a constant initial rotation speed Vs after the pouring start signal is input. The ladle tare weight Ws at the time when the tap opening sensor 8 detects the start of tapping is measured by the load cell 4, and the CPU 11
Store and store in. The time Ta is set in advance with reference to the time taken to sufficiently distinguish the amplitude of the noise of the load cell signal generated when the ladle is tilted from the weight value poured from the start of tapping, and the time of the load cell 4 during this period is set. Ignore the measured value.

After the time Ta has passed, the following control is performed. Ware tare weight measurement data at sampling time i
Assuming that (i) (Ws> W (i)) and the pouring weight at time i obtained from the pouring weight pattern diagram 30 is W ′ (i), the actual pouring weight and the control target value are obtained. Deviation e (i) of
Is represented by the following formula 1. e (i) = (Ws−W (i)) − W ′ (i) (1) The time when e (i) changes from negative to zero is Tb. The ladle continues to tilt at the initial rotation speed Vs until time. At this time, as shown in FIG. 7, a diagram 32 in which the actual weight is measured
Intersects with the pouring weight pattern diagram 30.

After the time Tb, the combined control region is entered, and the ladle tilting speed is changed from the initial rotation speed Vs to the speed by the feedback control. Here, step 2 of FIG. 5 and FIG.
As shown in Fig. 7, the pouring weight pattern diagram 3 already obtained
A new molten metal weight pattern diagram 31 is created by shifting a certain offset value d with respect to 0, and a target value for feedback is obtained from this.

Ladle tilting speed V at time i after time Tb
(I) is the measured tare weight value W (i), the initial ladle tare weight Ws, the target value W ″ (i) at time i obtained from the new pouring weight pattern diagram 31 and the tilting speed. The feedback proportional coefficient Kp to be converted is used to calculate by the equation 2. V (i) = a (i) * Kp * e (i) + b (i) * Vs ... (2) Here, e (i) = (Ws-W (i))-W '' (i) Further, a (i) is sequentially increased from 0 to 1 at each sampling time between times Tb and Tc. Along with this, b
(I) changes while satisfying the relationship of a (i) + b (i) = 1. The feedback proportional coefficient Kp is an empirical value determined by the shape of the ladle and the pouring weight, and the time from Tb to Tc is fixed.

After the time Tc, the pouring weight pattern diagram 31
Is a target feedback control region, and the ladle tilting speed V (i) is calculated by Equation 3. V (i) = Kp * e (i) + Ki * (e (i) + e (i-1) + ... e (i-m)) ... (3) Here, Ki is inclined from the measured weight value. It is an integral gain that is converted into a rolling speed.

The time Td is the time when the following expression 4 is satisfied for the first time. (Ws-W (i)) <(Wt-We) ... (4) After time Td, the state where the molten metal of (Wt-We) or more has been poured That is, the ladle 1 is tilted in the opposite direction at a preset speed Vf. Within a predetermined time Te, the molten metal weight We flows out from the ladle 1 and becomes almost the target pouring weight Wt.

In FIG. 8, sensors 15 and 16 are sensors for detecting the upper and lower limits of the molten metal surface in the sprue cup 2, and these sensors are radiation thermometers having a spot diameter of several millimeters. When the sensor 15 is ON, the molten metal is above the upper limit, and the sensor 16 is O
When it is FF, it is determined to be below the lower limit, and the pouring speed is controlled by the following method.

When the molten metal surface is below the upper limit and above the lower limit, a command voltage is sent to the servo motor amplifier 13 so as to tilt at the ladle tilting speed calculated by a predetermined control law. When the molten metal surface exceeds the upper limit, until the sensor 15 turns off,
The ladle is returned at a preset tilting speed to prevent the molten metal from overflowing, and after it has been turned off, the original control is resumed. When the molten metal surface falls below the lower limit, the sensor 16 is set to O
Tilt the ladle at a constant speed until it reaches N, increase the pouring speed, prevent the molten metal surface from falling, and return to the original control once it is turned on.

By the above method, automatic pouring is performed with the taught pouring speed pattern while keeping the level of the molten metal in the molten metal cup 2 within a certain range.

As described above, according to the automatic pouring control method of the present invention, the deviation between the target pouring amount immediately after tapping and the actual tapping weight is small, and the noise of the measuring instrument cannot be ignored in the initial period. Since the ladle is tilted at the rotation speed and then the composite control is switched to the feedback control, it is possible to perform the automatic pouring according to the set pouring pattern with good followability and stability.

[Brief description of drawings]

FIG. 1 is a schematic view of an automatic pouring device showing an embodiment of the present invention.

FIG. 2 is a system configuration diagram of the apparatus shown in FIG.

[Figure 3] Example of pouring speed pattern teaching

[Figure 4] Example of pouring weight pattern diagram

FIG. 5: Pouring weight pattern diagram after offset

FIG. 6 is a flowchart showing a process of creating FIG.

[Figure 7] Illustration of pouring process

FIG. 8 is an explanatory view of a molten metal surface upper limit sensor and a molten metal surface lower limit sensor.

[Explanation of symbols]

1 Ladle 2 Gate cup 3 Servo motor 4 Load cell 8 Gate sensor 9 Molten sensor 15 Molten metal upper limit sensor 16 Molten metal lower limit sensor 30 Molten metal weight pattern diagram calculated from molten metal velocity pattern diagram 31 Offset offset Pour weight pattern diagram 32 Plot pattern of actual pouring weight

Claims (3)

[Claims] 1. An automatic pouring control method for pouring the molten metal in a ladle into a mold, which teaches a pouring speed pattern diagram for pouring the mold, a target pouring weight and a target pouring time. Then, a pouring weight pattern diagram for the elapsed pouring time is calculated from the pouring speed pattern diagram, four control areas are set based on the ladle weight measurement data, and the first control immediately after the start of tapping. In the area, tilt the ladle at the determined initial rotation speed,
In the second control region, composite control for transitioning from initial rotation to feedback control is performed, in the third control region, feedback control with the calculated pouring weight pattern diagram as a control target is performed, and in the fourth control region, An automatic pouring control method characterized by inverting the ladle at a predetermined rotation speed. 2. In the third control area, a new pouring weight pattern diagram having a certain offset value is set to the calculated pouring weight pattern diagram, and feedback control is performed with this set as a control target. The automatic pouring control method according to claim 1, wherein 3. When the upper and lower limit positions of the molten metal in the sprue cup of the mold are detected, and when the molten metal comes out of this range, the predetermined control at this point is temporarily interrupted and the molten metal is returned in the range. The automatic pouring control method according to claim 1 or 2, wherein the pan is tilted, and after returning to within the range, the predetermined control is continued again.