JP2012045561A - Molten metal quantity control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molten metal quantity control system which can correctly recognize molten metal quantity at low cost.SOLUTION: When a molten metal surface contact detection part (detection bar 9) provided at a robot arm 5 is brought into contact with a molten metal surface, the rotation angle Aof the joint 6b in a robot arm 5 is detected by an angle detection part (encoder 10). On the basis of the rotation angle A, the molten metal quantity in a molten metal holding furnace 2 is detected.

Description

  The present invention relates to a system for managing the amount of molten metal in a molten metal holding furnace of a casting apparatus.

  The casting apparatus includes a casting machine such as a die casting machine and a molten metal holding furnace for holding molten metal, and casting is performed by supplying a predetermined amount of molten metal from the molten metal holding furnace to the casting machine. Since the amount of molten metal in the molten metal holding furnace is reduced by repeating the casting, it is necessary to manage the molten metal amount in the molten metal holding furnace and replenish the molten metal when the molten metal amount becomes too small.

  For example, Patent Literature 1 discloses a hot water level detector that detects a hot water surface height with a detection rod that detects contact with the hot water surface.

JP-A-6-229812

  If the detection rod as described above is provided at the full hot water position of the molten metal holding furnace, it can be detected whether or not the molten metal holding furnace is in a full hot water state. Therefore, for example, by supplying hot water to the molten metal holding furnace until it comes into contact with the detection rod, the amount of hot water in the current molten metal holding furnace is reduced by subtracting the amount of hot water for one cup of the ladle for each shot of casting from this state. Can be estimated.

  However, in the method using the detection rod as described above, it is difficult to accurately detect the amount of hot water. For example, since the detection rod is immersed many times in the hot molten metal, it may gradually melt and become shorter. Or the molten metal adhering to a detection rod may hang down from a detection rod, and may solidify in a state like an icicle. Thus, since the length of the detection rod is unstable, it is impossible to accurately detect the height of the hot water surface, and it is not possible to accurately detect the amount of hot water. If the current amount of hot water is calculated by subtracting the amount of hot water for one cup of the ladle from each inaccurate amount of hot water in this way, the calculated value will also be inaccurate. Can't figure out.

  For example, if a plurality of detection rods having different heights are provided, it is possible to detect the amount of hot water by detecting to which height the detection rod is filled with the molten metal. For example, if the detection rod with a height of 80 cm detects contact with the hot water surface, and the detection rod with a height of 100 cm does not detect contact with the hot water surface, the hot water surface height is between 80 cm and 100 cm. Can be detected. However, an error of the difference in height of the detection rod (20 cm in the above example) is unavoidable. For example, the error can be reduced by increasing the number of detection rods and reducing the difference in height, but the molten metal surface height that can still be detected is discontinuous and the number of detection rods that can be installed in the molten metal supply furnace Since there is a limit to this, it cannot be said that this measure can sufficiently increase the detection accuracy of hot water.

  Or it replaces with a detection stick | rod and the method of detecting the amount of hot water with the distance sensor which detects the hot_water | molten_metal surface height by non-contact is also considered. However, since the distance sensor is very expensive, the equipment cost increases, and the surface of the molten metal is glossy, so that accurate measurement by the distance sensor is very difficult.

  Further, as described above, in the method of calculating the current amount of hot water based on the amount of hot water at the time of full hot water, it is necessary to make sure that the molten metal is filled when the molten metal holding furnace is replenished. For example, when replenishing molten metal to a plurality of molten metal holding furnaces, if the hot water is installed in the molten metal holding furnace in turn, the hot water is loaded into the molten metal holding furnace before being distributed to all the molten metal holding furnaces. There is a risk that the molten metal installed will disappear. For this reason, there is a possibility that the molten metal in the molten metal holding furnace is used up and the casting machine is stopped before the hot water supply truck again loads the molten metal and visits again.

  An object of the present invention is to provide a hot water volume management system capable of accurately grasping the current hot water volume at a low cost.

  The present invention, which has been made to achieve the above object, includes a casting machine, a molten metal holding furnace for holding molten metal supplied to the casting machine, and a ladle provided at the tip, and the molten metal scooped with the ladle is used in the casting machine. A hot water amount management system for detecting the amount of molten metal in a molten metal holding furnace in a casting apparatus having a robot arm to be supplied, a hot water surface contact detection unit that is provided in the robot arm and detects contact with the molten metal surface, and a robot An angle detection unit that detects the rotation angle of the joint portion of the arm, and a hot water amount calculation unit that calculates the hot water amount based on the rotation angle of the joint portion when the hot water surface contact detection unit detects contact with the hot water surface. This is a hot water management system.

  As described above, in the hot water amount management system of the present invention, when the hot water surface contact detection unit comes into contact with the hot water surface, the angle of the joint portion of the robot arm is detected, and the hot water amount in the molten metal holding furnace is calculated based on this angle. To do. As a result, the amount of hot water for any angle of the joint can be calculated, so that it is possible to detect the amount of hot water much more accurately than the conventional system that detects the height of the hot water surface by contact with the detection rod. Become. Also, instead of directly detecting the hot water surface height with a detection rod or distance sensor, the amount of hot water is detected indirectly from the angle of the joint of the arm, so that the variation in the length of the detection rod and the distance sensor The amount of hot water can be accurately detected without being affected by the measuring ability. In addition, this hot water volume management system can detect the hot water volume for each shot of casting, so even if there is an error in the hot water volume detected due to fluctuations in the hot water surface, the correct amount of hot water is detected again in the next shot. can do.

  If the above-mentioned hot water amount management system is provided with a display unit that displays the amount of molten metal in the molten metal holding furnace of a plurality of casting apparatuses on a single screen, the driver of the hot water distribution car can see each display unit only by looking at the screen on the display unit. The amount of hot water in the molten metal holding furnace of the apparatus can be confirmed. As a result, hot water can be supplied by the amount necessary for the molten metal holding furnace in which the molten metal is reduced, so that the efficiency of the hot water distribution work is greatly improved.

  As described above, according to the hot water amount management system of the present invention, the current hot water amount can be accurately detected by calculating the hot water amount in the molten metal holding furnace based on the angle of the joint portion of the arm that moves the ladle. it can.

It is a side view of the casting apparatus provided with the hot water amount management system which concerns on embodiment of this invention. It is a side view which expands and shows the said casting apparatus. It is a top view of the casting installation provided with the said casting apparatus. It is a front view of the display part provided in the said casting installation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A casting apparatus 100 shown in FIG. 1 includes a casting machine 1, a molten metal holding furnace 2, and a molten metal supply means 3. The casting machine 1 is, for example, a die casting machine that casts a cylinder block of an engine, and molten metal (for example, molten aluminum) is supplied to a cavity from a supply port (not shown).

  The molten metal supply means 3 is composed of a robot arm 5 provided with a ladle 4 at the tip. The robot arm 5 in the illustrated example has three links 5a, 5b, and 5c, and each link 5a, 5b, and 5c is connected through two joint portions 6a and 6b. The base end portion of the robot arm 5 is rotatably attached to the base 7 via the joint portion 6c. The ladle 4 is rotatably attached to the tip end portion of the robot arm 5 via a rotation shaft 8. The joint portions 6a to 6c and the rotation shaft 8 of the robot arm 5 are respectively driven by a drive unit (not shown) and controlled by a control unit (not shown). By appropriately driving the joint portions 6 a to 6 c and the rotating shaft 8, the molten metal in the molten metal holding furnace 2 is scooped with the ladle 4 and supplied to the supply port of the casting machine 1.

  The amount of hot water held in the molten metal holding furnace 2 of the casting apparatus 100 is managed by the hot water amount management system according to an embodiment of the present invention. As shown in FIG. 2, the hot water amount management system includes a detection bar 9 as a hot water surface contact detection unit provided in the robot arm 5, and an encoder 10 as an angle detection unit provided in a joint part of the robot arm 5. The hot water amount calculation unit 11 that calculates the hot water amount based on signals from the detection rod 9 and the encoder 10 and display units 50 and 60 (see FIG. 3) that display the hot water amount calculated by the hot water amount calculation unit 11 are provided.

  The tip of the detection rod 9 is positioned below the rotary shaft 8 that rotates the ladle 4 relative to the robot arm 5. In the illustrated example, two detection rods 9 protrude downward from the rotating shaft 8. The two detection rods 9 have slightly different lengths, and the tips have slightly different heights. When the detection rod 9 detects contact with the hot water surface, the robot arm 5 automatically stops. As a result, the ladle 4 is disposed at a position where the molten metal can be scooped up, and a situation where the rotary shaft 8 is immersed in the molten metal can be avoided.

  The encoder 10 is provided at a joint portion of the robot arm 5, and in the present embodiment, the encoder 10 is provided at the joint portion 6b at the most distal side among the three joint portions 6a to 6c provided at the robot arm 5. The encoder 10 detects the rotation angle of the joint portion 6b, that is, the angle formed by the link 5b and the link 5c.

  Detection of the amount of hot water by the hot water management system is performed as follows. First, the robot arm 5 is driven to bring the ladle 4 close to the molten metal surface of the molten metal holding furnace 2, and when the detection rod 9 detects contact with the molten metal surface, the robot arm 5 is stopped. The rotation angle of the joint portion 6 b of the robot arm 5 at this time is detected by the encoder 10, and the detected rotation angle is transmitted to the hot water amount calculation unit 11. The hot water amount calculation unit 11 calculates the hot water amount based on the rotation angle of the joint portion 6b, and the calculated hot water amount is displayed on the display units 50 and 60.

Next, calculation of the hot water amount in the hot water amount calculation unit 11 will be described in detail. When casting is repeated and the molten metal in the molten metal holding furnace 2 is decreased, the molten metal surface is lowered as shown by a chain line in FIG. 2, and the stop position of the ladle 4 is moved downward. At this time, the rotation angle of the joint portion 6 b detected by the encoder 10 varies with the stop position of the ladle 4. In the illustrated example, the rotation angle A ₂ of the joint portion 6b in a state where the amount of hot water is reduced (dashed line) is larger than the rotation angle A ₁ in the full hot water state (solid line) (A ₁ <A ₂ ). That is, as the molten metal surface is lowered, the rotation angle of the joint portion 6b is increased. Since the ladle 4 moves along the same trajectory every time, if the correlation between the molten metal surface height and the rotation angle of the joint portion 6b is obtained, the molten metal surface height, and consequently the molten metal holding furnace, based on the rotation angle of the joint portion 6b. The amount of hot water 2 can be detected. Specifically, the correlation between the molten metal surface height and the rotation angle of the joint portion 6 b is stored in the molten metal amount calculation unit 11, and the molten metal surface is calculated from this correlation and the rotation angle of the joint portion 6 b transmitted from the encoder 10. Calculate the height and amount of hot water.

Since the ladle 4 is moved by the robot arm 5 having a plurality of joints, the ladle 4 moves along an arc-shaped locus in the vicinity of the molten metal surface. It is preferable to obtain a correlation between the molten metal surface height and the rotation angle of the joint portion 6b based on the arc-shaped locus. However, since the trajectory of the ladle 4 in the vicinity of the molten metal surface is substantially linear, the above correlation can be simplified by regarding the trajectory of the ladle 4 approximately as a straight line. Specifically, the current hot water amount H (weight) can be expressed by H = M− (A ₁ −A ₂ ) × K ₂ / K ₁ . Here, M is the full weight of the molten metal holding furnace, A ₁ is the rotation angle of the joint portion 6b in the full hot water state, A ₂ is the current rotation angle of the joint portion 6b, and K ₁ is a unit amount change in the molten metal surface height. the amount of change in the rotation angle of the joint portion 6b of the time, K ₂ represents the melt weight per unit molten metal surface level. Of the above parameters, M, A ₁ , K ₁ , and K ₂ are determined by the volume of the molten metal holding furnace 2, the structure of the robot arm 2, the material of the molten metal, and the like. Therefore, the values of M, A ₁ , K ₁ , and K ₂ are input in advance to the correlation equation stored in the hot water amount calculation unit 11, and the correlation equation in this state is transmitted from the encoder 10. By inputting the rotation angle A ₂ , the hot water amount H is calculated.

  According to the hot water amount management system, the hot water amount is calculated based on the rotation angle of the joint portion 6b of the robot arm 5, so that the current hot water amount can be accurately detected. Further, the detection of the amount of hot water is performed for each shot, that is, every time when the molten metal in the molten metal holding furnace 2 is scooped up by the ladle 4, for example, even if an error occurs in the detection result due to fluctuation of the molten metal surface, The accurate amount of hot water can be detected again. Further, when the molten metal is replenished to the molten metal holding furnace 2, it is not always necessary to replenish the molten metal up to a full hot water, and an arbitrary amount of molten metal may be replenished. Also in this case, the amount of hot water after replenishment can be accurately detected in the next shot.

  The rotation angle of the joint portion 6b detected by the encoder 10 is not only used for obtaining the amount of hot water as described above, but also by monitoring whether or not the rotation angle is within a predetermined range, Abnormal operation (for example, operation in which the ladle collides with the molten metal supply furnace) can be prevented.

  FIG. 3 shows a casting facility having a casting apparatus 100 equipped with the hot water management system as described above. This casting equipment includes a hot water supply station 200 and a hot water supply station 300. The hot water distribution station 200 is provided with a plurality (five in the illustrated example) of casting apparatuses 100, and the hot water station 300 is provided with a plurality of (three in the illustrated example) melting furnaces 30. The molten metal melted in the melting furnace 30 is discharged into the hot water supply car 40, and the hot water supply car 40 loaded with the molten metal moves from the hot water supply station 300 to the hot water supply station 200. The hot water supply wheel 40 supplies hot water to the molten metal holding furnace 2 of the casting apparatus 100 in which the molten metal is reduced. The water distribution vehicle 40 that has run out of molten metal returns to the hot water station 300 again, and the molten metal melted in the melting furnace 30 is supplied. By repeating the above, hot water distribution to each casting apparatus 100 is performed.

The casting facility is provided with a display unit that displays the amount of molten metal in the molten metal holding furnace 2 of each casting apparatus 100 on one screen. In the present embodiment, the display unit 50 is provided in the hot water supply station 200 and the display unit 60 is provided in the hot water supply station 300. For example, as shown in FIG. 4, the display unit 50 includes a full hot water amount M (kg) of each casting apparatus 100 (indicated by # 1 to # 5 in the drawing), a rotation angle A ₁ ( °), the current rotation angle A ₂ (°) of the joint portion 6b (in the immediately preceding shot), the amount of change K ₁ (° / mm) of the rotation angle of the joint portion 6b when the molten metal surface drops by ₁ mm, The difference Δh (mm) between the hot water surface height at the time of hot water and the current hot water surface height, the molten metal weight K ₂ (kg / mm) per 1 mm of the hot water surface height, and the present time calculated based on these values The amount of hot water used N (kg) is displayed. Of these, M, A ₁ , K ₁ , and K ₂ are preliminarily inputted with values determined by each casting apparatus 100. On the other hand, A ₂ displays a value detected by the encoder 10 for each shot. Further, as Δh and N, values calculated by the hot water amount calculation unit 11 are displayed based on the set value and the measured value. Note that the display items of the display unit 60 are the same as those of the display unit 50, and thus description thereof is omitted.

  From the difference between the full hot water amount M and the used hot water amount N, the current hot water amount H is calculated. From the current amount H of hot water, the amount of hot water used per shot, and the time per shot, the time until the molten metal in the molten metal holding furnace 2 runs out is calculated. When this time falls below a preset alarm issuing time, an alarm is issued, and for example, the number of the corresponding casting apparatus in the display unit 50 becomes red. The alarm issuing time is set to, for example, the time required for the hot water supply car 40 to go around the casting facility for hot water and hot water supply, and is displayed on the display units 50 and 60. For example, when the time required for the water distribution car 40 to go around the facility is 20 minutes, the molten metal holding furnace 2 of each casting apparatus 100 holds a quantity of molten metal that can continue casting for 20 minutes or more. For example, the casting apparatus 100 does not stop until at least the next hot water supply truck 40 arrives. Note that the alarm issuing time may be set longer than the above in order to reliably prevent the molten metal holding furnace 2 from running out of molten metal.

  The hot water delivery car 40 from which the molten metal has been poured out at the hot water station 300 exits the hot water station 300 and enters the hot water supply station 200. At the entrance of the hot water distribution station 200, a display unit 50 that displays the amount of hot water in the molten metal holding furnace 2 of each casting apparatus 100 is provided. The operator who operates the hot water supply truck 40 determines how much hot water is distributed to which molten metal holding furnace 2 by looking at the display on the display unit 50.

  For example, among the five casting apparatuses 100, when the alarms of the casting apparatuses 100 of # 2, # 4, and # 5 are issued, hot water is preferentially distributed to these casting apparatuses 100. For example, if hot water is supplied from the molten metal holding furnace 2 of the casting apparatus 100 of # 2 until the hot water is filled in sequence while the hot water supply truck 40 is circulated along the path indicated by the arrow in FIG. 3, the casting apparatus 100 of # 5 is reached. There is a risk that the molten metal of the water distribution car 40 will be lost before the operation. In this case, since the molten metal is not supplied to # 5 where the warning is issued, the casting apparatus 100 stops before the water distribution vehicle 40 returns again.

  In the present embodiment, each casting apparatus 100 is provided with a hot water amount management system, and the current accurate hot water amount is displayed on the display unit 50. Therefore, when the alarms of the three casting apparatuses 100 are issued as described above, it is sufficient to supply at least molten metal to the extent that the alarms of the respective casting apparatuses 100 are released. In this way, it is not always necessary to fill the molten metal holding furnace 2 where the alarm is issued, and it is sufficient to replenish the molten metal at least as long as the casting can be continued for at least the alarm time. Accordingly, it is possible to supply the molten metal as much as necessary to the molten metal holding furnace in which the molten metal is reduced, that is, it is possible to perform the hot water distribution just in time. After the hot water is distributed in this way, the amount of hot water is calculated and displayed on the display units 50 and 60 in the next shot, so that even if the molten metal holding furnace 2 is not full, the operator can The amount of hot water can be accurately grasped.

  In the hot water station 300, the ingot is melted in each melting furnace 30 to produce a molten metal. At this time, the ingot may be melted as much as necessary based on the amount of hot water of each casting apparatus 100 displayed on the display unit 50. For example, when the time required for melting the ingot is 10 minutes, and the time required for the hot water supply truck 40 to discharge and distribute the hot water is 20 minutes, each of the molten metals that can be continuously cast for at least 30 minutes. What is necessary is just to be hold | maintained at the molten metal holding furnace 2. FIG. Accordingly, the display unit 60 disposed in the hot water station 300 is set longer by the time required for the alarm issuing time to melt the ingot.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the correlation between the rotation angle A ₂ of the joint portion and the hot water amount H is approximately regarded as a straight line. However, the present invention is not limited to this, and the actual locus of the ladle 4 by the robot arm 5 is obtained. Based on this trajectory, the correlation between the rotation angle A ₂ and the hot water amount H may be obtained. In this case, since a correlation faithful to the actual trajectory is obtained, the amount of hot water can be calculated more accurately.

  In the above embodiment, the encoder as the angle detection unit is provided at the joint 6b on the most distal side of the robot arm. However, the present invention is not limited to this, and the encoder is provided at other joints or at a plurality of locations. May be.

  Moreover, the display item of the display parts 50 and 60 is not restricted to the above, For example, you may make it display only the amount of hot water of each casting apparatus 100. FIG. Moreover, the installation location of the display units 50 and 60 is not limited to the above, and may be provided in a location that is easy for the operator to see.

  Moreover, in said embodiment, although the case where the amount of hot water of a molten metal holding furnace was managed by the weight was shown, it is not restricted to this, For example, the amount of hot water can also be managed by a volume or height.

  In the above embodiment, the casting machine 1 is a die-casting machine. However, if the casting machine supplies a molten metal with a ladle from a molten metal holding furnace, the casting machine 1 may be another casting machine (for example, a low-pressure casting machine). May be.

DESCRIPTION OF SYMBOLS 1 Casting machine 2 Molten metal holding furnace 3 Molten metal supply means 4 Ladle 5 Robot arm 5a, 5b, 5c Link 6a, 6b, 6c Joint part 7 Base 8 Rotating shaft 9 Detection rod (molten surface contact detection part)
10 Encoder (angle detector)
11 Hot water amount calculation unit 30 Melting furnace 40 Hot water distribution car 50 Display unit 100 Casting device 200 Hot water distribution station 300 Hot water station A ₁ Rotation angle of joint (when hot water is full)
A ₂ Rotation angle of joint H Hour amount K ₁ Amount of change in rotation angle of joint when the surface height changes by unit amount K ₂ Molten metal weight per unit surface height M Full hot water amount N Used hot water amount Δh Full hot water The difference between the current level and the current level

Claims (1)

A molten metal holding furnace in a casting apparatus, comprising: a casting machine; a molten metal holding furnace that holds molten metal supplied to the casting machine; and a robot arm that is provided with a ladle at a tip and supplies molten metal scooped with the ladle to the casting machine. A hot water volume management system for managing the hot water volume of
A robot surface detection unit that detects contact with the molten metal surface, an angle detection unit that detects the rotation angle of the joint of the robot arm, and a molten metal surface contact detection unit detects contact with the molten metal surface. A hot water volume management system comprising: a hot water volume calculation unit that calculates the hot water volume based on the rotation angle of the joint when it is done.

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