Ladle hot water supply system for die casting machines

Abstract

This disclosure describes a ladle molten metal supply system for a die-casting machine that can stably transport large quantities of molten metal even if the amount of molten metal transported increases due to the enlargement of the die-casting machine. [Solution] The ladle molten metal supply device for a die-casting machine comprises a ladle, a moving unit configured to move the ladle between a forward limit position and a retracted limit position, and a control unit. The moving unit includes an arm, a lifting unit, and a horizontal swivel unit. The control unit is configured to perform a first process of drawing molten metal from a molten metal holding furnace using the ladle when the ladle is in the retracted limit position, a second process of synchronously controlling the operation of the lifting motor and the horizontal swivel motor with respect to the operation of the spindle motor, and a third process of supplying molten metal from the ladle to an injection unit configured to inject molten metal into the die of the die-casting machine when the ladle is in the forward limit position.

Description

Technical Field

[0001] The present disclosure relates to a ladle water supply device for a die-casting machine.

Background Art

[0002] Patent Document 1 discloses a ladle water supply system for supplying molten metal to a die-casting machine. The ladle water supply system is configured to supply molten metal to the injection sleeve of the die-casting machine by using a moving device that moves the entire ladle water supply device and a rotating mechanism that rotates the ladle. Specifically, at the start of the supply operation, the moving mechanism starts to lower the entire ladle water supply device, and the rotating mechanism rotates the ladle. Thereby, by supplying the molten metal while approaching the outflow position of the molten metal from the ladle to the bottom of the injection sleeve, it is intended to mitigate the entrainment of air due to the turbulent flow of the molten metal and suppress the splashing and scattering of the molten metal due to the fall of the molten metal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, for example, for the purpose of reducing costs by reducing the number of parts and manufacturing processes, it has been considered to manufacture complex large parts by integral molding by casting. In this case, it is necessary to supply molten metal to a large or extra-large die-casting machine, but the molten metal pumped out from the molten metal holding furnace by the ladle of the ladle water supply device becomes a larger amount, that is, a higher weight than before. In addition, the moving distance of the ladle from the molten metal holding furnace to the injection sleeve of the die-casting machine also becomes longer. In addition, due to the layout of the die-casting machine and the ladle water supply device, the ladle may not be able to move linearly between the molten metal holding furnace and the injection sleeve, and the moving trajectory may become complicated.

[0005] Therefore, this disclosure describes a ladle molten metal supply system for a die-casting machine that can stably transport large quantities of molten metal even if the amount of molten metal transported increases due to the enlargement of the die-casting machine. [Means for solving the problem]

[0006] An example of a ladle hot water supply system for a die-casting machine comprises a ladle, a moving unit configured to move the ladle between a forward limit position and a backward limit position, and a control unit. The moving unit includes an arm, a lifting unit, and a horizontal swivel unit. The arm includes a tip connected to the ladle and a base end connected to at least one of the lifting unit and the horizontal swivel unit, and includes an arm configured to swivel along a vertical plane, and a spindle motor configured to rotate the base end along the vertical plane. The lifting unit includes a lifting motor configured to move the arm in the vertical direction. The horizontal swivel unit includes a horizontal swivel motor configured to swivel the arm along a horizontal plane. The control unit is configured to perform a first process of pumping molten metal from the molten metal holding furnace using the ladle when the ladle is in the retracted limit position, a second process of synchronously controlling the operation of the lifting motor and the horizontal swivel motor in relation to the operation of the spindle motor, and a third process of supplying molten metal from the ladle to the injection section of the die-casting machine when the ladle is in the forward limit position. [Effects of the Invention]

[0007] According to the ladle molten metal supply system for die-casting machines described herein, even if the amount of molten metal transported increases due to the enlargement of the die-casting machine, it becomes possible to stably transport large quantities of molten metal. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view showing an example of a ladle hot water supply system. [Figure 2] Figure 2 shows a side view of the ladle heating system in Figure 1 and a cross-section of an example of a molten metal holding furnace. [Figure 3] Figure 3 is a diagram illustrating the operation of drawing molten metal from the molten metal holding furnace using a ladle feeding device. [Figure 4] Figure 4 illustrates the process of transporting the molten metal, scooped up by the ladle, towards the injection nozzle of the die-casting machine. [Figure 5] Figure 5 is a diagram illustrating the operation of supplying molten metal, pumped out by a ladle, to the injection section of a die-casting machine. [Figure 6] Figure 6 is a diagram illustrating the timing of the operation of other motors in conjunction with the operation of the spindle motor. [Figure 7] Figure 7 is a flowchart illustrating the process for correcting the amount of rudder descent. [Modes for carrying out the invention]

[0009] In the following descriptions, the same reference numeral will be used for identical elements or elements with the same function, and redundant explanations will be omitted. Furthermore, in this specification, when referring to the top, bottom, right, and left of a figure, the direction of the reference numeral in the figure will be used as the reference.

[0010] [Configuration of a Ladle Hot Water Heating System] First, the configuration of the ladle molten metal supply device 1 will be explained, mainly with reference to Figures 1 and 2. The ladle molten metal supply device 1 is configured to pump out the molten metal M (molten metal) held by the molten metal holding furnace 100 (see Figures 2 to 4) using a ladle 2 and supply the molten metal M to the injection section 200 (see Figure 5) of a die-casting machine (not shown).

[0011] As illustrated in Figures 2 to 4, the molten metal holding furnace 100 is configured to heat the molten metal M, which is a liquid of molten metal (e.g., aluminum alloy), to a predetermined temperature (e.g., about 650°C to 680°C) to maintain the molten state of the molten metal M. As illustrated in Figure 5, the injection unit 200 includes, for example, a cylindrical injection sleeve 210 and a plunger 220. When molten metal M is supplied from an inlet 211 provided on the upper surface of the injection sleeve 210, the plunger advances toward the mold side of the die-casting machine. As a result, the molten metal M is poured into the cavity formed in the mold. Once the filling of the mold cavity with molten metal M is complete, the casting is completed through processes such as mold clamping, mold opening, extrusion, removal, cooling, and post-processing.

[0012] Returning to Figures 1 and 2, the ladle hot water supply device 1 comprises a base 10, a lifting unit 20, a horizontal swivel unit 30, an arm unit 40, a ladle 2, a measuring unit 50 (see Figures 2 to 4), and a controller Ctr (control unit) (see Figure 1).

[0013] The base 10 is a cylindrical body extending vertically, with its lower end fixed to the floor surface. The base 10 is configured to support elements (lifting section 20, horizontal rotation section 30, and arm section 40) positioned above it. A support plate 11 extending along the horizontal plane is provided at the upper end of the base 10.

[0014] The lifting section 20 is provided at the upper end of the base 10. The lifting section 20 supports elements (horizontal swivel section 30 and arm section 40) positioned above it, and is configured to move them up and down (up and down) along the vertical direction. The lifting section 20 includes a guide post 21, a housing 22, and a lifting mechanism 23.

[0015] The guide post 21 is inserted into the base 10 and is configured to move up and down with respect to the base 10. The housing 22 includes a top wall 22a and side walls 22b. The top wall 22a is in the shape of a flat plate extending along a horizontal plane and is connected to the upper end of the guide post 21. The side walls 22b are in the shape of a square cylinder and are connected to the top wall 22a so as to extend downward from the peripheral edge of the top wall 22a. An opening 22c through which a lifting motor 23c (described later) can pass is provided along the vertical direction on one main surface of the side wall 22b.

[0016] The lifting mechanism 23 is, for example, a screw jack. The lifting mechanism 23 may include a screw shaft 23a, a gear case 23b, and a lifting motor 23c. The upper end of the screw shaft 23a is fixed to the top wall 22a of the housing 22 so as to extend downward from the top wall 22a. The gear case 23b and the lifting motor 23c are mounted on the support plate 11 of the base 10. The gear case 23b houses a worm shaft (not shown). The worm shaft is screwed with the screw shaft 23a extending through the gear case 23b and converts its rotation into the up and down movement of the screw shaft 23a.

[0017] The lifting motor 23c is connected to the worm shaft. The lifting motor 23c is configured to operate based on an instruction signal from the controller Ctr and drive the worm shaft to rotate. That is, the rotational force of the lifting motor 23c is transmitted to the screw shaft 23a via the worm shaft, causing the screw shaft 23a to move up and down. Thereby, the elements (the horizontal swing part 30 and the arm part 40) arranged above the lifting part 20 move up and down via the housing 22. In the examples of FIGS. 1 to 5, the lifting part 20 includes two lifting mechanisms 23, but may include at least one lifting mechanism 23.

[0018] The horizontal turning part 30 is provided on the ceiling wall 22a. The horizontal turning part 30 is configured to support an element (arm part 40) arranged above the horizontal turning part 30 and to turn this element along a horizontal plane. The horizontal turning part 30 includes a housing 31, a rotating shaft 32, and a horizontal turning motor 33.

[0019] The housing 31 is fixed on the ceiling wall 22a. As illustrated in FIGS. 1 and 2, the rotating shaft 32 is attached to the housing 31 so as to be rotatable around its central axis Ax1. The upper end part of the rotating shaft 32 is connected to the arm part 40. The horizontal turning motor 33 is connected to the rotating shaft 32 via gears or the like not shown. The horizontal turning motor 33 operates based on an instruction signal from the controller Ctr and is configured to rotationally drive the rotating shaft 32 around its central axis Ax1. That is, the rotational force of the horizontal turning motor 33 is transmitted to the rotating shaft 32 via gears or the like, and the rotating shaft 32 is rotated around its central axis Ax1. Thereby, the arm part 40 connected to the upper end part of the rotating shaft 32 turns (horizontal turning) along a horizontal plane.

[0020] The arm part 40 includes a support member 41, an arm 42, a spindle motor 43, and a ladle drive motor 44. The support member 41 includes a support plate 41a extending along a horizontal plane and a support plate 41b extending along a vertical plane. The support plate 41a is fixed to the upper end part of the rotating shaft 32. The support plate 41b is fixed to the support plate 41a so as to extend upward from the support plate 41a. The support plate 41b supports the arm 42 on one main surface side and supports the spindle motor 43 and the ladle drive motor 44 on the other main surface side.

[0021] The arm 42 is constituted by a link mechanism. In the examples of FIGS. 1 to 5, the arm is constituted by a five-link mechanism including four links that form a substantially parallelogram and function as slave links, and one link that is connected to one of the four links and functions as a prime mover link.

[0022] A ladder 2 is attached to the tip 42a of the arm 42 so as to be rotatable around a rotation axis Ax2 extending horizontally, as illustrated in Figures 1 and 2. The base end 42b of the arm 42 (one end of the link that acts as the driving link) is attached to the support plate 41b so as to be rotatable around a rotation axis Ax3 extending horizontally, as illustrated in Figure 2. In other words, the base end 42b of the arm 42 is indirectly connected to the horizontal swivel section 30 via the support member 41. The base end 42b of the arm 42 may also be directly or indirectly connected to at least one of the lifting section 20 and the horizontal swivel section 30.

[0023] The spindle motor 43 is mounted on the support plate 41b and connected to the base end 42b of the arm 42. The spindle motor 43 operates based on instruction signals from the controller Ctr and is configured to rotate the base end 42b, thereby causing the tip end 42a to pivot around the rotation axis Ax3. As the base end 42b of the arm 42 rotates around the rotation axis Ax3, the tip end 42a of the arm 42 pivots along a vertical plane (vertical rotation).

[0024] The rudder drive motor 44 is mounted on the support plate 41b and connected to a rudder drive mechanism (not shown) that rotates the rudder 2 along a vertical plane. The rudder drive mechanism may be located, for example, within the links that make up the arm 42. The rudder drive mechanism may include, for example, a timing belt that is rotationally driven by the rudder drive motor 44, or a rigid rotating bar configured to rotate in conjunction with the rotation of the timing belt. The rudder drive motor 44 operates based on instruction signals from the controller Ctr and is configured to rotate the rudder drive mechanism, thereby rotating the rudder 2 around the rotation axis Ax2. That is, the rudder 2 rotates along a vertical plane (vertical rotation) in conjunction with the driving of the rudder drive mechanism.

[0025] At least one of the lifting motor 23c, horizontal slewing motor 33, main shaft motor 43, and rudder drive motor 44 may be equipped with a reduction gear. At least one of the lifting motor 23c, horizontal slewing motor 33, main shaft motor 43, and rudder drive motor 44 may be, for example, a servo motor. When a servo motor is used, the resolution is extremely high, making it possible to position the object being moved by the motor with extremely high precision.

[0026] The ladle 2 is a container for scooping molten metal M from the molten metal holding furnace 100. The ladle 2 moves between a forward limit position P1 (see Figure 4) where it is located near the injection unit 200 and a backward limit position P2 (see Figure 4) where it is located near the molten metal holding furnace 100, as the lifting unit 20, horizontal swivel unit 30, and arm unit 40 operate as described above. In other words, the lifting unit 20, horizontal swivel unit 30, and arm unit 40 constitute a moving unit 3 that moves the ladle 2 between the forward limit position P1 and the backward limit position P2.

[0027] As illustrated in Figure 2, the measuring unit 50 is configured to measure the height of the molten metal M held by the molten metal holding furnace 100. The measuring unit 50 is configured to transmit the measured molten metal height data to the controller Ctr. The measuring unit 50 may be, for example, a non-contact height measuring sensor or a contact height measuring sensor.

[0028] The controller Ctr is configured to control the entire ladle water heater 1. Based on, for example, a program recorded on a recording medium (not shown) or operation input from an operator, the controller Ctr generates instruction signals to operate each part of the ladle water heater 1 (e.g., the lifting motor 23c, the horizontal slewing motor 33, the main shaft motor 43, and the ladle drive motor 44), and transmits these instruction signals to each of them.

[0029] The ladle water heater 1 may have one controller Ctr, or it may have a controller group (control unit) composed of multiple controllers Ctr. If the ladle water heater 1 has a controller group, the control of each part of the ladle water heater 1 may be realized by one controller Ctr, or by a combination of two or more controllers Ctr.

[0030] The controller Ctr is configured to execute the process of pumping molten metal M from the molten metal holding furnace 100 using the ladle 2 when the ladle 2 is at the retraction limit position P2. In this case, the controller Ctr may also include the process of controlling the spindle motor 43 to raise and lower the ladle 2 between the retraction limit position P2 and the molten metal holding furnace 100. That is, the controller Ctr may include the process of controlling the spindle motor 43 to lower the ladle 2 from the retraction limit position P2 toward the molten metal holding furnace 100, and the process of raising the ladle 2 from the molten metal holding furnace 100 toward the retraction limit position P2.

[0031] The controller Ctr is configured to perform a process of synchronously controlling the operation of the lifting motor 23c and the horizontal slewing motor 33 in relation to the operation of the spindle motor 43. In this case, the controller Ctr may also include a process of controlling the spindle motor 43, the lifting motor 23c and the horizontal slewing motor 33 to move the rudder 2 between the forward limit position P1 and the backward limit position P2. Here, in this document, "synchronous control" means operating the driven motor (at least one of the lifting motor 23c and the horizontal slewing motor 33) when the position of the tip 42a of the arm 42 (the rotation angle of the spindle motor 43) reaches a preset position. In other words, "synchronous control" in this book does not involve raising and lowering and / or horizontally rotating the arm 42 using mechanical elements (e.g., shafts, cams, gears, clutches, etc.) in conjunction with the operation of the spindle motor 43, but rather uses software (e.g., a programmable logic controller (PLC) or motion controller, etc.) to achieve positional control of the lifting motor 23c and the horizontal rotation motor 33 in conjunction with the operation of the spindle motor 43.

[0032] The controller Ctr is configured to supply molten metal M to the injection unit 200 by the ladder 2 when the ladder 2 is at its forward limit position P1. In this case, the controller Ctr may also include the process of controlling the ladder drive motor 44 to rotate the ladder 2 vertically.

[0033] The controller Ctr is configured to perform a process to correct the amount of descent of the ladle 2 from the retraction limit position P2 toward the molten metal holding furnace 100, based on the value of the molten metal surface height measured by the measuring unit 50. Details of the correction process for the amount of descent of the ladle 2 will be described later.

[0034] [Molten metal supply operation by ladle heating system] Next, with reference to Figures 3 to 6, the operation of supplying molten metal M to the injection section 200 by the ladle molten metal supply device 1 will be explained. In the following explanation, it will be assumed that the ladle 2 starts moving from a state where it is in the retraction limit position P2.

[0035] First, the controller Ctr controls the spindle motor 43 and the rudder drive motor 44 to move the arm 42 and change the orientation of the rudder 2. As a result, the rudder 2 rotates vertically so that it is tilted slightly downward from its neutral position (where the upper opening of the rudder 2 is approximately horizontal; see the rudder 2 drawn with a dashed line in Figure 3) (see the rudder 2 drawn with a solid line in Figure 3). At the same time, the rudder 2 descends from its retraction limit position P2 toward the molten metal holding furnace 100 and is immersed in the molten metal M held in the molten metal holding furnace 100 (see arrow Ar1 in Figure 3 and column (A) in Figure 6).

[0036] Next, the controller Ctr stops the operation of each motor (lifting motor 23c, horizontal slewing motor 33, spindle motor 43, and ladle drive motor 44) until a predetermined time has elapsed while the ladle 2 is immersed in the molten metal M (see column (B) in Figures 3 and 6). This fills the ladle 2 with molten metal M.

[0037] Next, the controller Ctr controls the spindle motor 43 to move the arm 42. This causes the ladle 2 to rise from the molten metal holding furnace 100 toward the retraction limit position P2 (see column (C) in Figure 6).

[0038] Next, the controller Ctr stops the operation of each motor (lifting motor 23c, horizontal slewing motor 33, spindle motor 43, and rudder drive motor 44) until a predetermined time has elapsed while the rudder 2 is in the retraction limit position P2 (see column (D) in Figure 6). As a result, the rudder 2 is left stationary in the retraction limit position P2. Therefore, the molten metal M adhering to the outer surface of the rudder 2 drips into the molten metal holding furnace 100, and the undulation of the molten metal M scooped up by the rudder 2 stops, so that the amount of molten metal M in the rudder 2 becomes appropriate.

[0039] Next, the controller Ctr controls the rudder drive motor 44 to vertically rotate the rudder 2 so that it returns to a neutral position (see column (E) in Figure 6). This keeps the rudder 2 in a neutral position while it moves from the retracted limit position P2 to the forward limit position P1.

[0040] Next, the controller Ctr controls the spindle motor 43 and the lifting motor 23c to advance the arm 42 from the retraction limit position P2 towards the forward limit position P1, while the lifting unit 20 raises the arm 40 (see column (F) in Figure 6). As a result, the ladder 2 (the tip 42a of the arm 42) moves forward and rises. Next, the controller Ctr controls the spindle motor 43 and the horizontal slewing motor 33 to continue advancing the arm 42 towards the forward limit position P1, while the horizontal slewing unit 30 rotates the arm 40 horizontally (see column (G) in Figure 6). As a result, the ladder 2 (the tip 42a of the arm 42) moves forward and rotates horizontally, reaching the forward limit position P1. During the forward rise and forward rotation of the ladder 2, the lifting motor 23c and the horizontal slewing motor 33 are synchronously controlled with respect to the spindle motor 43. Therefore, as illustrated in Figure 4, the rudder 2 moves from the retraction limit position P2 to the advance limit position P1 via a movement trajectory L that exhibits a complex, curved shape.

[0041] Next, the controller Ctr controls the rudder drive motor 44 to vertically rotate the rudder 2 so that it is in an inverted position (with the upper opening of the rudder 2 facing downwards) (see arrow Ar2 in Figure 5 and column (H) in Figure 6). This initiates the supply of molten metal M from the rudder 2 to the injection unit 200.

[0042] Next, the controller Ctr stops the operation of each motor (lifting motor 23c, horizontal slewing motor 33, spindle motor 43, and rudder drive motor 44) until a predetermined time has elapsed while the rudder 2 is in an inverted position (see column (I) in Figure 6). As a result, the entire volume of molten metal M in the rudder 2 is poured into the injection unit 200.

[0043] Next, the controller Ctr controls the rudder drive motor 44 to vertically rotate the rudder 2 so that it returns to a neutral position (see column (J) in Figure 6). This completes the supply of molten metal M from the rudder 2 to the injection unit 200.

[0044] Next, the controller Ctr controls the spindle motor 43 and the horizontal slewing motor 33 to move the arm 42 backward from the forward limit position P1 towards the backward limit position P2, while the horizontal slewing unit 30 rotates the arm 40 horizontally (see column (K) in Figure 6). As a result, the ladder 2 (the tip 42a of the arm 42) rotates horizontally while moving backward. Next, the controller Ctr controls the spindle motor 43 and the lifting motor 23c to continue moving the arm 42 backward towards the backward limit position P2, while the lifting unit 20 lowers the arm 40 (see column (L) in Figure 6). As a result, the ladder 2 (the tip 42a of the arm 42) descends while moving backward and reaches the backward limit position P2. During the backward rotation and backward descent of the ladder 2, the lifting motor 23c and the horizontal slewing motor 33 are synchronously controlled with respect to the spindle motor 43. At this time, the rudder 2 moves from the forward limit position P1 to the reverse limit position P2 via the same movement trajectory L as when it moved forward and upward and when it turned forward.

[0045] With the above steps completed, the series of operations for supplying molten metal M to the injection unit 200 by the ladle molten metal supply device 1 is finished.

[0046] [Correction process for radle descent] Next, with reference to Figure 7, an example of the correction process for the descent of Laddle 2 will be explained. Before starting the correction process, please understand the following: • Amount of molten metal M drawn out per cycle by ladle 2 (e.g., volume of ladle 2) • The initial state before the start of casting by the die-casting machine, the height of the molten metal M held in the molten metal holding furnace 100 (initial molten metal height) H0 • Internal shape of the molten metal holding furnace 100 Furthermore, in the previous cycle, before the molten metal M is pumped out of the molten metal holding furnace 100 by the ladle 2, the measuring unit 50 measures the height of the molten metal M in the molten metal holding furnace 100 (the actual height of the molten metal in the previous cycle) H1, and this data is stored in the controller Ctr.

[0047] When the correction process is initiated, the controller Ctr first calculates the predicted amount of molten metal level drop DA, which is the amount of molten metal M that will be drawn out of the molten metal holding furnace 100 by the ladle 2 during the current casting cycle (see step S1 in Figure 7). For example, if the internal shape of the molten metal holding furnace 100 is such that the opening area OA is approximately equal in the height direction, the amount of molten metal level drop DA during the current casting cycle may be calculated by dividing the amount of molten metal drawn out per cycle A by the opening area OA (i.e., DA = A / OA). Alternatively, if the internal shape of the molten metal holding furnace 100 is such that the opening area OA changes in the height direction (for example, the internal shape of the molten metal holding furnace 100 narrows as it goes downwards), the amount of molten metal level drop DA during the current casting cycle may be calculated by applying a predetermined correction (for example, multiplying by a correction coefficient α) to the value obtained by dividing the amount of molten metal drawn out per cycle A by the opening area OA (i.e., DA = α × A / OA). Furthermore, the molten metal level drop DA calculated as described above is the average drop in the molten metal level M in the molten metal holding furnace 100, and therefore can also be called the average molten metal level drop.

[0048] Next, the controller Ctr calculates the estimated molten metal height H2 that is predicted to occur when the molten metal M is drawn out of the molten metal holding furnace 100 by the ladle 2 during the current casting cycle (see step S2 in Figure 7). In other words, H2 can be said to be the theoretical value of the molten metal height in the molten metal holding furnace 100 after the current casting cycle has been executed (hereinafter also referred to as the estimated molten metal height H2). For example, the estimated molten metal height H2 for the current casting cycle may be calculated by subtracting the amount of molten metal level drop DA from the previous actual molten metal height H1 (H2 = H1 - DA). Here, the previous actual molten metal height H1 is similarly calculated by subtracting the amount of molten metal level drop DA from the actual molten metal height of the cycle before that. Therefore, the estimated molten metal height H2 for the current casting cycle may be calculated by subtracting the value obtained by multiplying the number of times the current casting cycle has been performed (the number of times the molten metal has been drawn out of the molten metal holding furnace 100 by the ladle 2) N by the amount of molten metal level drop DA from the initial molten metal height H0 (H2 = H0 - N × DA).

[0049] Next, the controller Ctr corrects the amount of descent of the ladle 2 in the current casting cycle based on the calculated estimated molten metal height H2. For example, the amount of descent of the ladle 2 in the next casting cycle is corrected so that when the ladle 2 descends from the retraction limit position P2 toward the molten metal holding furnace 100, the entire ladle 2 is submerged in the molten metal M in the molten metal holding furnace 100 (see step S3 in Figure 7). Then, the controller Ctr instructs the spindle motor 43 to a target value to achieve the corrected descent amount, causing the ladle 2 to descend from the retraction limit position P2 toward the molten metal holding furnace 100, and the ladle 2 to pump out the molten metal M from the molten metal holding furnace 100 (see the same).

[0050] Next, the actual molten metal level H3 in the molten metal holding furnace 100 after the current casting cycle has been executed is measured by the measuring unit 50 (see step S4 in Figure 7). Then, the controller Ctr determines whether the amount of molten metal M pumped out from the molten metal holding furnace 100 was appropriate (see step S5 in Figure 7). Specifically, the controller Ctr calculates the pumped-out amount ΔH (i.e., ΔH = H2 - H3) by subtracting the actual molten metal level H3 at the end of the current casting from the estimated molten metal level H2, and determines whether this is within a predetermined range (for example, between thresholds Th1 and Th2) (i.e., whether Th1 ≤ ΔH ≤ Th2). Alternatively, it may be determined whether the value obtained by subtracting the estimated molten metal level H2 from the actual molten metal level H3 is within a predetermined range.

[0051] If the pumping amount ΔH is within a predetermined range (YES in step S5 of Figure 7), the controller Ctr determines that the pumping amount of molten metal M was appropriate and terminates the correction process. On the other hand, if the pumping amount ΔH is outside the predetermined range (NO in step S5 of Figure 7), the controller Ctr determines that the pumping amount ΔH of molten metal M was abnormal, stops the ladle molten metal supply device 1 (see step S6 of Figure 7), and then terminates the correction process. An abnormal pumping amount ΔH may occur, for example, due to insufficient replenishment of molten metal M to the molten metal holding furnace 100 (insufficient pouring), or spillage of molten metal M from the ladle 2. After the ladle molten metal supply device 1 is stopped due to an abnormality in the pumping amount ΔH, an inspection of the ladle molten metal supply device 1 may be performed by an operator to confirm and correct the abnormality.

[0052] [Effect] As shown in the above example, when the main spindle motor 43 operates, the trailing shaft motors 23c and 33 follow suit. Therefore, when the position of the tip 42a of the arm 42 (the rotation angle of the main spindle motor 43) reaches a preset position, the lifting motor 23c or the horizontal swivel motor 33 follows, causing the arm 40 to move up and down or rotate horizontally. Thus, the movement of the tip 42a of the arm 42 can be flexibly set according to the size of the die-casting machine. As a result, even if the amount of molten metal M to be transported increases with the size of the die-casting machine, it becomes possible to stably transport a large amount of molten metal M.

[0053] In the above example, the controller Ctr can control the spindle motor 43 to lower the ladle 2 from the retraction limit position P2 toward the molten metal holding furnace 100. In this case, the ladle 2 is lowered solely by the vertical rotation of the tip 42a of the arm 42 due to the control of the spindle motor 43. Therefore, when the ladle 2 pumps out the molten metal M, the positional accuracy of the ladle 2 is ensured while the ladle 2 moves with the minimum possible distance. Furthermore, in the above example, the controller Ctr can control the spindle motor 43, the lifting motor 23c, and the horizontal slewing motor 33 to move the ladle 2 between the forward limit position P1 and the retraction limit position P2. As a result, not only the spindle motor 43 but also the lifting motor 23c and the horizontal slewing motor 33 are operated, so the ladle 2 moves between the forward limit position P1 and the retraction limit position P2 with the minimum possible distance. Therefore, it is possible to achieve both precise positional accuracy in scooping out the molten metal M by the ladle 2 and a reduction in the movement time of the ladle 2.

[0054] In the above example, the amount of descent of the ladle 2 is corrected based on the value of the molten metal height measured by the measuring unit 50. Therefore, even if the molten metal M held by the molten metal holding furnace 100 drops, it is possible to pump out the required amount of molten metal M with the ladle 2. Furthermore, in the above example, the controller Ctr can appropriately detect whether or not there is an abnormality in the ladle molten metal supply device 1 by making a judgment based on the pumping amount ΔH.

[0055] As shown in the above example, the measuring unit 50 can be a non-contact height measuring sensor. In this case, since the molten metal M does not adhere to the sensor, it becomes possible to measure the height of the molten metal M with high accuracy.

[0056] As shown in the above example, the spindle motor 43 and the ladle drive motor 44 can be servo motors. In this case, using servo motors as the spindle motor 43 and the ladle drive motor 44 allows for high-precision control of the position of the ladle 2. As a result, the ladle 2 descends accurately to an appropriate height relative to the molten metal M held by the molten metal holding furnace 100. Therefore, it becomes possible to pump out the required amount of molten metal M with the ladle 2. Furthermore, because the position of the ladle 2 is controlled with high precision, fluctuations in the molten metal level are reduced when the ladle 2 enters the molten metal M held by the molten metal holding furnace 100. Therefore, even when the molten metal level is measured by a contact-type height measuring sensor, for example, the adhesion of molten metal M to the sensor is limited to a relatively narrow range. Thus, even when using a contact-type height measuring sensor, it becomes possible to detect the molten metal level well.

[0057] [Differentiation] The disclosures herein should be considered in all respects to be illustrative and not restrictive. Various omissions, substitutions, and modifications may be made to the above examples without departing from the claims and the gist thereof.

[0058] (1) The measuring unit 50 may measure the molten metal level of the molten metal holding furnace 100 in real time (continuously). The measuring unit 50 may also measure the molten metal level of the molten metal holding furnace 100 when it receives an instruction signal from the controller Ctr.

[0059] (2) If the amount of molten metal M held in the molten metal holding furnace 100 falls below the lower limit, the measuring unit 50 may detect that the amount has fallen below the lower limit, and the molten metal M may be automatically replenished in the molten metal holding furnace 100. Alternatively, when the measuring unit 50 detects that the amount has fallen below the lower limit, the controller Ctr may notify the operator through a notification unit (e.g., speaker, display, etc.), and the operator may replenish the molten metal M in the molten metal holding furnace 100. In this case, the controller Ctr may stop the ladle molten metal supply device 1 for the operator to replenish the molten metal M.

[0060] [Other examples] Example 1. An example of a ladle hot water supply system for a die-casting machine comprises a ladle, a moving unit configured to move the ladle between a forward limit position and a backward limit position, and a control unit. The moving unit includes an arm, a lifting unit, and a horizontal swivel unit. The arm includes a tip connected to the ladle and a base end connected to at least one of the lifting unit and the horizontal swivel unit, and includes an arm configured to swivel along a vertical plane, and a spindle motor configured to rotate the base end along the vertical plane. The lifting unit includes a lifting motor configured to move the arm in the vertical direction. The horizontal swivel unit includes a horizontal swivel motor configured to swivel the arm along a horizontal plane. The control unit is configured to perform three processes: a first process of scooping molten metal from the molten metal holding furnace using the ladle when the ladle is at its retracted limit position; a second process of synchronously controlling the operation of the lifting motor and the horizontal swivel motor in response to the operation of the spindle motor; and a third process of supplying molten metal from the ladle to the injection section of the die-casting machine when the ladle is at its forward limit position. In this case, when the spindle motor operates, the following shafts, the lifting motor and the horizontal swivel motor, operate in accordance. Therefore, when the position of the tip of the arm (the rotation angle of the spindle motor) reaches a preset position, the lifting motor or the horizontal swivel motor moves in response, causing the arm to move up and down or rotate horizontally. Thus, the movement of the tip of the arm can be flexibly set according to the size of the die-casting machine. As a result, even if the amount of molten metal to be transported increases with the size of the die-casting machine, it becomes possible to stably transport a large amount of molten metal.

[0061] Example 2. In the apparatus of Example 1, the first process may include controlling the spindle motor to lower the ladle from the retracted limit position toward the molten metal holding furnace, and the second process may include controlling the spindle motor, lifting motor, and horizontal swivel motor to move the ladle between the forward limit position and the retracted limit position. In this case, in the first process, the ladle is lowered by the vertical swivel motion of the tip of the arm only, by the control of the spindle motor. Therefore, when scooping out molten metal with the ladle, the positional accuracy of the ladle is ensured while the ladle moves with the minimum possible travel distance. Furthermore, in the second process, not only the spindle motor but also the lifting motor and horizontal swivel motor are operated, so the ladle moves between the forward limit position and the retracted limit position with the minimum possible travel distance. Thus, it is possible to achieve both positional accuracy in scooping out molten metal with the ladle and a reduction in the ladle's travel time.

[0062] Example 3. The apparatus of Example 2 further comprises a measuring unit configured to measure the height of the molten metal held in the molten metal holding furnace, and the first process may further include a process of correcting the amount of ladle descent based on the value of the molten metal height measured by the measuring unit. In this case, the amount of ladle descent is corrected based on the value of the molten metal height measured by the measuring unit. Therefore, even if the level of molten metal held in the molten metal holding furnace drops, it becomes possible to pump out the required amount of molten metal with the ladle.

[0063] Example 4. In the apparatus of Example 3, the measuring unit may be non-contact. In this case, since molten metal does not adhere to the sensor, it becomes possible to measure the molten metal surface height with high accuracy.

[0064] Example 5. In any of the devices in Examples 1 to 4, the moving part further includes a ladle drive motor configured to rotate the ladle along a vertical plane, and the spindle motor and ladle drive motor may be servo motors. In this case, using servo motors as the spindle motor and ladle drive motor allows for high-precision control of the ladle's position. As a result, the ladle descends accurately to an appropriate height relative to the molten metal surface height held by the molten metal holding furnace. Therefore, it becomes possible to scoop out the required amount of molten metal with the ladle. Furthermore, because the ladle's position is controlled with high precision, fluctuations in the molten metal surface height are reduced when the ladle enters the molten metal held by the molten metal holding furnace. Therefore, even when the molten metal surface height is measured by a contact-type height measuring sensor, for example, the adhesion of molten metal to the sensor is limited to a relatively narrow range. Therefore, even when using a contact-type height measuring sensor, it becomes possible to detect the molten metal surface height accurately. [Explanation of symbols]

[0065] 1...Rudder molten metal supply device, 2...Rudder, 20...Lifting section, 23c...Lifting motor, 30...Horizontal swivel section, 33...Horizontal swivel motor, 40...Arm section, 42...Arm, 42a...Tip section, 42b...Base section, 43...Main shaft motor, 44...Rudder drive motor, 50...Measurement section, 100...Molten metal holding furnace, 200...Injection section, Ctr...Controller (control unit), P1...Forward limit position, P2...Reverse limit position.

Claims

1. Ladle and, A moving part configured to move the aforementioned rudder between a forward limit position and a reverse limit position, It includes a control unit, The aforementioned moving part includes an arm, a lifting part, and a horizontal rotating part. The aforementioned arm portion is An arm comprising a tip connected to the ladder and a base connected to at least one of the lifting section and the horizontal swivel section, configured to be rotatable along a vertical plane, The base end includes a spindle motor configured to rotate along a vertical plane, The lifting unit includes a lifting motor configured to move the arm unit in the vertical direction, The horizontal swivel section includes a horizontal swivel motor configured to rotate the arm along a horizontal plane. The control unit, When the ladle is in the retraction limit position, a first process is performed in which the molten metal is pumped out of the molten metal holding furnace by the ladle, A second process that synchronously controls the operation of the lifting motor and the horizontal slewing motor with respect to the operation of the spindle motor, A ladle molten metal supply device for a die-casting machine, configured to perform a third process of supplying molten metal from the ladle to the injection section of the die-casting machine when the ladle is in the forward limit position.

2. The first process includes controlling the spindle motor to lower the ladle from the retraction limit position toward the molten metal holding furnace, The apparatus according to claim 1, wherein the second process includes controlling the spindle motor, the lifting motor, and the horizontal slewing motor to move the rudder between the forward limit position and the reverse limit position.

3. The molten metal holding furnace further comprises a measuring unit configured to measure the height of the molten metal surface, The apparatus according to claim 2, wherein the first process further includes a process of correcting the amount the ladle descends based on the value of the water surface height measured by the measuring unit.

4. The apparatus according to claim 3, wherein the measuring unit is non-contact.

5. The moving part further includes a ladder drive motor configured to rotate the ladder along a vertical plane, The apparatus according to any one of claims 1 to 4, wherein the spindle motor and the rudder drive motor are servo motors.

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