Molten Metal Supply Device

Abstract

A molten metal supply device designed to mount a ladle-rotating motor on a support frame and dispose a ladle-rotating rotation transfer mechanism in a predetermined link of a ladle-carrying link mechanism so as to be able to perform precise position control (tilt angle control) of a ladle. The rotation transfer mechanism is driven by the ladle-rotating motor mounted on the support frame so as to rotate the ladle. The rotation transfer mechanism is provided in a link of the ladle-carrying link mechanism for carrying the ladle. The rotation transfer mechanism is constituted by two parallel linkages. Each parallel linkage has a pair of bar links whose opposite ends are attached to two rotors respectively. When the ladle-rotating motor is being stopped, the ladle can be kept in a predetermined posture by the parallel linkages even if the ladle-carrying link mechanism has any operating posture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cutaway plan view showing a main portion of a molten metal supply device according to an embodiment of the present invention;

FIG. 2 is a front view showing a main portion of the molten metal supply device according to the embodiment of the present invention when a ladle is in a melting furnace;

FIG. 3 is a front view showing a main portion of the molten metal supply device according to the embodiment of the present invention when the ladle is being carried;

FIG. 4 is a front view showing a main portion of the molten metal supply device according to the embodiment of the present invention when the ladle is above a shot sleeve;

FIG. 5 is an explanatory view showing a ladle-rotating rotation transfer mechanism in the state of FIG. 2;

FIG. 6 is an explanatory view showing the state where the ladle has been rotated (tilted) to scoop molten metal in the state of FIG. 5;

FIG. 7 is an explanatory view showing the ladle-rotating rotation transfer mechanism in the state of FIG. 3;

FIG. 8 is an explanatory view showing the state where the ladle has been rotated (tilted) into the posture where the ladle can scoop the molten metal in the state of FIG. 7 for a trial operation or the like;

FIG. 9 is an explanatory view showing the ladle-rotating rotation transfer mechanism in the state of FIG. 4;

FIG. 10 is an explanatory view showing the state where the ladle has been rotated (tilted) to inject the molten metal in the state of FIG. 9;

FIG. 11 is a partially removed perspective view showing a main portion of the molten metal supply device according the embodiment of the present invention;

FIG. 12 is a perspective view showing a main portion of the molten metal supply device according the embodiment of the present invention, where a part of members have been removed;

FIG. 13 is a perspective view showing a main portion of the molten metal supply device according the embodiment of the present invention, where a part of members have been removed;

FIG. 14 is a perspective view showing a main portion of the molten metal supply device according the embodiment of the present invention, where a part of members have been removed;

FIG. 15 is a perspective view showing a main portion of the molten metal supply device according the embodiment of the present invention, where a part of members have been removed; and

FIG. 16 is a perspective view showing a main portion of the molten metal supply device according the embodiment of the present invention, where a part of members have been removed.

DETAILED DESCRIPTION OF THE EMBODIMENT

An embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described below with reference to the drawings.

FIGS. 1-10 show a molten metal supply device for use in a cold-chamber die-casting machine according to an embodiment of the present invention. FIG. 1 is a partially cutaway plan view showing a main portion of a molten metal supply device according to an embodiment of the present invention; FIG. 2 is a front view showing a main portion of the molten metal supply device according to the embodiment of the present invention when a ladle is in a melting furnace; FIG. 3 is a front view showing a main portion of the molten metal supply device according to the embodiment of the present invention when the ladle is being carried; FIG. 4 is a front view showing a main portion of the molten metal supply device according to the embodiment of the present invention when the ladle is above a shot sleeve; FIG. 5 is an explanatory view showing a ladle-rotating rotation transfer mechanism in the state of FIG. 2; FIG. 6 is an explanatory view showing the state where the ladle has been rotated (tilted) to scoop molten metal in the state of FIG. 5; FIG. 7 is an explanatory view showing the ladle-rotating rotation transfer mechanism in the state of FIG. 3; FIG. 8 is an explanatory view showing the state where the ladle has been rotated (tilted) into the posture where the ladle can scoop the molten metal in the state of FIG. 7 for a trial operation or the like; FIG. 9 is an explanatory view showing the ladle-rotating rotation transfer mechanism in the state of FIG. 4; and FIG. 10 is an explanatory view showing the state where the ladle has been rotated (tilted) to inject the molten metal in the state of FIG. 9.

In FIGS. 1-10, a support frame 1 is fixedly provided in a site where a die-casting machine has been installed. A ladle-carrying link mechanism 2 is constituted by a five-bar linkage provided on the support frame 1. A ladle 3 is carried between a not-shown melting furnace and a not-shown shot sleeve by the ladle-carrying link mechanism 2. A ladle-carrying motor 4 is mounted on the support frame 1 so as to drive the ladle-carrying link mechanism 2. A ladle-rotating motor 6 is mounted on the support frame 1 so as to rotate (tilt) the ladle 3. A geared motor to which a speed reducing mechanism (speed reducing gear train) is attached integrally is used as each of the ladle-carrying motor 4 and the ladle-rotating motor 6. The ladle-carrying motor 4 rotates a ladle-carrying output shaft 5 (hereinafter referred to as “output shaft 5” simply) with its speed reducing gear train. The ladle-rotating motor 6 rotates a ladle-rotating output shaft 7 (hereinafter referred to as “output shaft 7” simply) with its speed reducing gear train.

The ladle-carrying link mechanism 2 is constituted by a first link 8, a second link 10, a third link 11, a fourth link 12 and a fifth link 13. One end portion of the first link 8 is rotatably retained on the output shaft 7 on the ladle-rotating motor 6 side through a rolling bearing so that the first link 8 can rotate around the output shaft 7. One end portion of the second link 10 is rotatably retained on a first spindle 9 through a rolling bearing. The first spindle 9 is rotatably retained on the other end portion of the first link 8 through a rolling bearing. One end portion of the third link 11 is inserted and fixed into the output shaft 5 on the ladle-carrying motor 4 side so that the third link 11 can be driven to rotate around the one end portion thereof by rotation of the ladle-carrying motor 4. One end portion of the fourth link 12 is rotatably coupled with an intermediate portion of the second link 10. The other end portion of the third link 11 is rotatably coupled with an intermediate portion of the fourth link 12. One end portion of the fifth link 13 is rotatably retained on the support frame 1 through a suitable rotary retention member so that the fifth link 13 can be kept coaxial with the output shaft 7. A base end portion of the ladle 3 is rotatably retained on the other end portion of the second link 10 as will be described later.

In the ladle-carrying link mechanism 2 having the aforementioned structure, the third link 11 which is a driving bar is driven to rotate with the output shaft 5 through a speed reducing mechanism by the ladle-carrying motor 4 so that the other four links 8, 10, 12 and 13 make cooperative motion. Thus, the base end portion of the ladle 3 (rotation center of the ladle 3) is moved along a trajectory shown by the two-dot chain line in FIGS. 2-4.

In FIG. 1 and FIGS. 5-16, a first parallel linkage 14 is included in the first link 8, and a second parallel linkage 15 is included in the second link 10. The two linkages, that is, the first parallel linkage 14 and the second parallel linkage 15 form a ladle-rotating rotation transfer mechanism for rotating (tilting) the ladle 3. When the output shaft 7 is driven to rotate by rotation of the ladle-rotating motor 6, the rotation transfer mechanism (the first parallel linkage 14 and the second parallel linkage 15) is driven by a mechanism which will be described later. As a result, the ladle 3 rotates around its base end portion so that the ladle 3 can be positioned in a desired rotational position.

The first parallel linkage 14 is constituted by a first rotor 16, a pair of first parallel bar links 17A and 17B (forming a parallel linkage), and a second rotor 18. The first rotor 16 is received in one end portion of the first link 8 and rotatably retained on the one end portion of the first link 8 through a rolling bearing. The first rotor 16 is also fixed to the output shaft 7 on the ladle-rotating motor 6 side. Each first bar link 17A, 17B is received in the first link 8 and one end portion of the first bar link 17A, 17B is rotatably coupled with the first rotor 16. The second rotor 18 is received in the other end portion of the first link 8 and fixed to the first spindle 9 so that the second rotor 18 is rotatably retained on the other end portion of the first link 8. The other end portion of each of the paired first bar links 17A and 17B is rotatably coupled with the second rotor 8.

The second parallel linkage 15 is constituted by a third rotor 19, a pair of second parallel bar links 20A and 20B (forming a parallel linkage), and a fourth rotor 22. The third rotor 19 is received in one end portion of the second link 10 and fixed to the first spindle 9 so that the third rotor 19 is rotatably retained on the one end portion of the second link 10. The third rotor 19 rotates integrally with the second rotor 18. Each second bar link 20A, 20B is received in the second link 10 and one end portion of the second bar link 20A, 20B is rotatably coupled with the third rotor 19. The fourth rotor 22 is received in the other end portion of the second link 10 and fixed to the second spindle 21 which is rotatably retained on the other end portion of the second link 10 through a rolling bearing. Thus, the fourth rotor 22 is rotatably retained on the other end portion of the second link 10. The other end portion of each of the paired second bar links 20A and 20B is rotatably coupled with the fourth rotor 22.

The base end portion of the ladle 3 is also fixed to the second spindle 21 which is rotatably retained on the other end portion of the second link 10. The ladle 3 is designed to rotate around its base end portion integrally with the second spindle 21 and the fourth rotor 22.

In this embodiment, the first bar links 17A and 17B and the second bar links 20A and 20B are rigid bars manufactured by cutting a metal plate. The paired first bar links 17A and 17B are attached to the first rotor 16 and the second rotor 18 with a phase difference of 90 degrees from each other. Likewise, the paired second bar links 20A and 20B are attached to the third rotor 19 and the fourth rotor 22 with a phase difference of 90 degrees from each other. The paired parallel bar links are disposed with a phase difference of 90 degrees from each other in order to prevent any dead point from appearing in the operating ranges of the first bar links 17A and 17B and the second bar links 20A and 20B. In this manner, the first parallel linkage 14 and the second parallel linkage 15 can be operated smoothly and reliably.

In the ladle-rotating rotation transfer mechanism (the first parallel linkage 14 and the second parallel linkage 15) configured thus, the rotation of the ladle-rotating motor 6 is decelerated and outputted as the rotation of the output shaft 7. The first rotor 16 fixed to the output shaft 7 is thus driven to rotate integrally with the output shaft 7. As a result, the second rotor 18 and the first spindle 9 are rotated through the paired first bar links 17A and 17B so that the third rotor 19 rotates integrally with the first spindle 9. The fourth rotor 22 and the second spindle 21 are rotated through the paired second bar links 20A and 20B so that the second spindle 21 rotates. Thus, the ladle 3 rotates integrally with the second spindle 21. Accordingly, when the ladle-rotating motor 6 is rotated in a desired direction by a desired quantity of rotation, the ladle 3 can be put into a posture where the ladle 3 can scoop molten metal in the melting furnace, a posture where the ladle 3 can be transported when the ladle 3 is carried, or a posture where the ladle 3 can inject the molten metal into the shot sleeve.

Next, additional description will be made about how the ladle-rotating rotation transfer mechanism (the first parallel linkage 14 and the second parallel linkage 15) can keep the posture where the ladle 3 can be transported when the ladle 3 is carried. When the ladle 3 is carried, the first link 8 rotates (rocks) around the output shaft 7 on the ladle-rotating motor 6 side disposed on the one end side of the first link 8, and the second link 10 rotates (rocks) around the first spindle 9 disposed on the other end side of the first link 8. When the rotation of the output shaft 7 is kept locked in this state, the ladle 3 is kept into a posture corresponding to the position where the rotation of the output shaft 7 is stopped at that time, regardless of the rotation (rocking) angles of the first link 8 and the second link 10, that is, the posture where the first link 8 and the second link 10 are tilted. This is because the first parallel linkage 14 and the second parallel linkage 15 are designed as a parallelogram linkage. That is, the second rotor 18, the third rotor 19 and the fourth rotor 22 coupled with the first bar links 17A and 17B and the second bar links 20A and 20B rotate correspondingly to the angles with which the first link 8 and the second link 10 rotate (rock). Thus, the displacements of the angles are canceled so that the ladle 3 can be put into a fixed posture. In this embodiment, when the ladle 3 is carried, the first link 8 rotates (rocks) at a maximum angle of 150° around the output shaft 7 as its rotation center. Accordingly, the first rotor 16 rotates at a maximum angle of 150° relatively to the first link 8.

Next, additional description will be made about the rotation (tilting) of the ladle 3. With reference to the posture where the ladle 3 is transported (the posture shown in FIGS. 2, 3, 4, 5, 7 and 9), the ladle 3 has to have a posture where the ladle 3 has been turned (tilted) right at a maximum angle of 60° in the carrying position of FIGS. 2 and 5 in order to scoop molten metal in the melting furnace, as shown in FIG. 6. In order to inject the molten metal into the shot sleeve, the ladle 3 has to have a molten metal injection posture where the ladle 3 has been turned left at an angle of 90° in the carrying position of FIGS. 4 and 9, as shown in FIG. 10. That is, the ladle 3 has to be turned (tilted) at a total angle of 150°. For trail operation control or the like, the ladle 3 has to be able to rotate (tilt) at an angle of 150° in any carrying position.

Accordingly, the first parallel linkage 14 has to be designed to provide rotation at an angle of 300° which is a total of the rotation angle of 150° required for keeping the posture of the ladle 3 when the ladle 3 is carried and the rotation angle of 150° required for rotating (tilting) the ladle 3 as described above. In this embodiment, the first parallel linkage 14 is designed to be able to provide rotation at an angle of 310° in consideration of a safety margin.

The second link 10 rotates (rocks) at a maximum angle of 80° around the first spindle 9 when the ladle 3 is carried. Thus, the third rotor 19 and the fourth rotor 22 rotate at a maximum angle of 80° relatively to the second link 10. Accordingly, the second parallel linkage 15 has to be designed to provide rotation at an angle of 230° which is a total of the rotation angle of 80° required for keeping the posture of the ladle 3 when the ladle 3 is carried and the rotation angle of 150° required for rotating (tilting) the ladle 3 as described above. In this embodiment, the second parallel linkage 15 is designed to be able to provide rotation at an angle of 240° in consideration of a safety margin.

In the background art, a sprocket (chain wheel) and a chain (mating winding member) are used to keep the posture of a ladle and rotate the ladle. In such a configuration, not to say, it is easy to attain the aforementioned rotation of 310°, or it is easy to attain rotation of a more angle. However, when a mating winding member such as a chain is used, reduction in transfer accuracy due to looseness, extensional deformation, or the like, cannot be avoided, as described previously. In this embodiment, the aforementioned rotation of 310° or 240° can be attained by the first parallel linkage 14 using the paired bar links 17A and 17B free from extension or bending and the second parallel linkage 15 using the paired bar links 20A and 20B free from extension or bending. In order to secure the required rotation angle and miniaturize the mechanism by use of such rigid bar links, parallel linkages are constituted by rigid rotators and rigid bar links in this embodiment. Further, the required rotation angle is also secured by improving the shapes of end portions of the bar links.

Next, detailed description will be made about the aforementioned end portion shapes of the paired first bar links 17A and 17B and the attachment structures thereof. One end portion (end portion on the first rotor 16 side) of the first bar link 17A which is one of the paired first bar links is rotatably attached to the first rotor 16 through a pin and a bearing in a position outside the end surface of the output shaft 7. Therefore, there is no fear that the one end portion of the first bar link 17A interferes with the output shaft 7 on the ladle-rotating motor 6 side when the first bar link 17A moves in accordance with the rotation of the first link 8 or when the first bar link 17A moves in accordance with the rotation of the first rotor 16 in order to rotate (tilt) the ladle 3. For this reason, the one end portion of the first bar link 17A is formed into a linear shape. On the other hand, one end portion (end portion on the first rotor 16 side) of the first bar link 17B which is the other of the paired first bar links is rotatably attached to the first rotor 16 through a pin and a bearing in a position inside the end surface of the output shaft 7. Therefore, if the one end portion of the first bar link 17B is formed into a linear shape in the same manner as the one end portion of the first bar link 17A, the one end portion of the first bar link 17B will interfere with the output shaft 7 on the ladle-rotating motor 6 side when the first bar link 17B moves in accordance with the rotation of the first link 8 or when the first bar link 17B moves in accordance with the rotation of the first rotor 16 in order to rotate (tilt) the ladle 3. For this reason, the one end portion of the first bar link 17B is formed into a curved shape with a larger curvature radius than the outer diameter of the output shaft 7 in order to avoid interference with the output shaft 7. FIG. 10 shows the state where the one end portion of the first bar link 17B has been close to the output shaft 7. At this time, the one end portion (curved portion) of the first bar link 17B forms a partial ring coaxial with the output shaft 7 due to a slight distance from the outer circumference of the output shaft 7.

The other end portion (end portion on the second rotor 18 side) of the first bar link 17B is rotatably attached to the second rotor 18 through a pin and a bearing in a position outside the end surface of the first spindle 9. Therefore, there is no fear that the other end portion of the first bar link 17B interferes with the first spindle 9 when the first bar link 17B moves. For this reason, the other end portion of the first bar link 17B is formed into a linear shape. On the other hand, the other end portion (end portion on the second rotor 18 side) of the first bar link 17A is rotatably attached to the second rotor 18 through a pin and a bearing in a position inside the end surface of the first spindle 9. Therefore, if the other end portion of the first bar link 17A is formed into a linear shape in the same manner as the other end portion of the first bar link 17B, the other end portion of the first bar link 17A will interfere with the first spindle 9 when the first bar link 17A moves. For this reason, the other end portion of the first bar link 17A is formed into a curved shape with a larger curvature radius than the outer diameter of the first spindle 9 in order to avoid interference with the first spindle 9. FIG. 8 shows the state where the other end portion of the first bar link 17A has been close to the first spindle 9. At this time, the other end portion of the first bar link 17A forms a partial ring coaxial with the first spindle 9 due to a slight distance from the outer circumference of the first spindle 9.

Next, detailed description will be made about the aforementioned end portion shapes of the paired second bar links 20A and 20B and the attachment structures thereof. One end portion (end portion on the third rotor 19 side) of each second bar link 20A, 20B is rotatably attached to the third rotor 19 through a pin and a bearing in a position inside the end surface of the first spindle 9. Therefore, the one end portion of each second bar link 20A, 20B is formed into a curved shape with a larger curvature radius than the outer diameter of the first spindle 9 in order to avoid interference with the first spindle 9. On the other hand, the other end portion (end portion on the fourth rotor 22 side) of each second bar link 20A, 20B is rotatably attached to the fourth rotor 22 through a pin and a bearing in a position inside the end surface of the second spindle 21. Therefore, the other end portion of each second bar link 20A, 20B is formed into a curved shape with a larger curvature radius than the outer diameter of the second spindle 21 in order to avoid interference with the second spindle 21.

FIGS. 11 and 12 are main portion perspective views showing the one-end-portion side shapes of the paired first bar links 17A and 17B and the attachment structures thereof, from which views the first link 8 has been removed. FIG. 11 shows a state close to the posture in FIG. 9, and FIG. 12 shows a state corresponding to the posture in FIG. 10. As shown in FIGS. 11 and 12, there is no fear that the one end portion of the first bar link 17A interferes with the output shaft 7 on the ladle-rotating motor 6 side. As described above, the one end portion of the first bar link 17A is therefore formed into a linear shape. If the one end portion of the first bar link 17B is formed into a linear shape, the one end portion of the first bar link 17B will interfere with the output shaft 7. As described above, the one end portion of the first bar link 17B is therefore formed into a curved shape in order to avoid interference with the output shaft 7. In FIGS. 11 and 12, the reference numeral 31 represents a rotary flange which can fix and retain one end portion of the first link 8 and rotate integrally with the one end portion of the first link 8. The rotary flange 31 is rotatably attached to the circumference of the output shaft 7 on the ladle-rotating motor 6 side.

FIGS. 13 and 14 are main portion perspective views showing the other-end-portion side shapes of the paired first bar links 17A and 17B and the attachment structures thereof, and the one-end-portion side shapes of the paired second bar links 20A and 20B and the attachment structures thereof, from which views the first link 8 and the second link 10 have been removed. FIG. 13 shows a state close to the posture in FIG. 5, and FIG. 14 shows a state close to the posture in FIG. 9. As shown in FIGS. 13 and 14, there is no fear that the other end portion of the first bar link 17B interferes with the first spindle 9. As described above, the one end portion of the first bar link 17B is therefore formed into a linear shape. If the other end portion of the first bar link 17A is formed into a linear shape, the other end portion of the first bar link 17A will interfere with the first spindle 9. As described above, the other end portion of the first bar link 17A is therefore formed into a curved shape in order to avoid interference with the first spindle 9. If the one end portion of each of the paired second bar links 20A and 20B is formed into a linear shape, the one end portion of the second bar link 20A, 20B will interfere with the first spindle 9. As described able, the one end portion of each second bar link 20A, 20B is therefore formed into a curved shape in order to avoid interference with the first spindle 9.

FIGS. 15 and 16 are main portion perspective views showing the other-end-portion side shapes of the paired second bar links 20A and 20B and the attachment structures thereof, from which views the second link 10 and the ladle 3 have been removed. FIGS. 15 and 16 show a state in the posture where the ladle 3 is being transported. There is a difference in perspective angle between FIG. 15 and FIG. 16. As shown in FIGS. 15 and 16, if the other end portion of each paired second bar link 20A, 20B is formed into a linear shape, the other end portion of the second bar link 20A, 20B will interfere with the second spindle 21. As described above, the other end portion of each second bar link 20A, 20B is therefore formed into a curved shape in order to avoid interference with the second spindle 21.

In this embodiment, the one end portions and the other end portions of the second bar links 20A and 20B are disposed in positions inside the end surface of the first spindle 9 or the second spindle 21 as described above. This is because the second bar links 20A and 20B are pinched from their opposite ends in order to secure reliability in mechanical strength of attachment of the second bar links 20A and 20B. To this end, each of the opposite ends of the second bar links 20A and 20B is shaped into a curved shape. However, the attachment structure of each second bar link 20A, 20B may be made similar to that of each first bar link 17A, 17B if reliability in mechanical strength can be secured. In this case, one of the end portions of each second bar link 20A, 20B can be formed into a linear shape in the same manner as that of each first bar link 17A, 17B.

Due to the end portion shapes of the first bar links 17A and 17B and the attachment structures thereof and the end portion shapes of the second bar links 20A and 20B and the attachment structures thereof, the operating range and the function required as this kind of molten metal supply device can be achieved in spite of the parallel linkages using bar links made of rigid bodies free from bending.

As has been described above, in the molten metal supply device according to this embodiment, the ladle-rotating motor 6 is mounted on the support frame 1 side, and the ladle-rotating rotation transfer mechanism is disposed in the first and second links of the ladle-carrying link mechanism 2. Due to this configuration, the ladle-carrying link mechanism can be made comparatively light in weight, and the appearance can be improved. In the molten metal supply device, the ladle-rotating rotation transfer mechanism is constituted by combination of two parallel linkages (the first parallel linkage 14 and the second parallel linkage 15) each having a pair of bar links (the first bar links 17A and 17B or the second bar links 20A and 20B) whose opposite ends are rotatably attached to two rotors respectively. Accordingly, the ladle-rotating rotation transfer mechanism has no looseness or no extensional deformation, but is superior in rotation transfer accuracy. It is therefore possible to perform precise position control (tilt angle control) of the ladle. Thus, the quantity of molten metal scooped by the ladle can be made precisely constant. Each pair of the first bar links 17A and 17B and the second bar links 20A and 20B are attached to their corresponding rotors with a phase difference of 90° from each other. Accordingly, there appears no dead point in the first parallel linkage 14 and the second parallel linkage 15. Thus, the first parallel linkage 14 and the second parallel linkage 15 can be operated smoothly and reliably. Further, at least one of the end portions of each of the paired first bar links 17A and 17B and the paired second bar links 20A and 2DB is formed into a curved shape in order to avoid interference with a shaft member (the output shaft 7, the first spindle 9 or the second spindle 21). Accordingly, each bar link can be displaced with no trouble. It is therefore possible to reliably achieve the operating range and the function required as this kind of molten metal supply device.

Claims

1. A molten metal supply device in which a predetermined quantity of molten metal is scooped from a melting furnace by a ladle, and the molten metal in the ladle carried to an upper side of a supply port of a shot sleeve is injected into the shot sleeve through the supply port, the molten metal supply device comprising: a ladle-carrying link mechanism for carrying the ladle;a ladle-rotating rotation transfer mechanism which is provided in a predetermined link of the ladle-carrying link mechanism; anda ladle-rotating motor for driving the rotation transfer mechanism so as to rotate the ladle, the ladle-rotating motor being mounted on a support frame;wherein the rotation transfer mechanism is constituted by two parallel linkages each having a pair of bar links whose opposite ends are attached to two rotors respectively and which form a parallel linkage, so that the ladle can be kept in a predetermined posture by the parallel linkages even if the ladle-carrying link mechanism has any posture when the ladle-rotating motor is being stopped.

2. A molten metal supply device according to Claim l, wherein at least one end portion of each of the bar links of the parallel linkages is formed into a curved shape so as to avoid interference with any of shaft members rotating integrally with the rotors.

3. A molten metal supply device in which a predetermined quantity of molten metal is scooped from a melting furnace by a ladle, and the molten metal in the ladle carried to an upper side of a supply port of a shot sleeve is injected into the shot sleeve through the supply port, the molten metal supply device comprising: a ladle-carrying motor mounted on a support frame;a ladle-carrying output shaft for decelerating rotation of the ladle-carrying motor and outputting the decelerated rotation;a ladle-rotating motor mounted on the support frame;a ladle-rotating output shaft for decelerating rotation of the ladle-rotating motor and outputting the decelerated rotation;a first link whose one end portion is rotatably retained on the ladle-rotating output shaft;a first spindle rotatably provided on the other end portion of the first link;a second link whose one end portion is rotatably retained on the first spindle;a third link whose one end portion is fixed to the ladle-carrying output shaft;a fourth link whose one end portion is rotatably coupled with an intermediate portion of the second link and which has an intermediate portion with which the other end portion of the third link is rotatably coupled;a fifth link whose one end portion is rotatably retained around the ladle-rotating output shaft and whose other end portion is rotatably coupled with the other end portion of the fourth link;a first rotor which is received in the one end portion of the first link and fixed to the ladle-rotating output shaft;a pair of first bar links which are received in the first link and whose one end portions are rotatably attached to the first rotor so as to form a parallel linkage;a second rotor which is received in the other end portion of the first link and fixed to the first spindle, and to which the other end portions of the pair of the first bar links are rotatably attached respectively;a third rotor which is received in the one end portion of the second link and fixed to the first spindle;a pair of second bar links which are received in the second link and whose one end portions are rotatably attached to the third rotor so as to form a parallel linkage;a fourth rotor which is received in the other end portion of the second link and fixed to a second spindle rotatably retained on the other end portion of the second link and to which the other end portions of the pair of the second bar links are rotatably attached respectively; anda ladle whose base end portion is fixed to the second spindle; wherein:a five-bar link age constituted by the first, second, third, fourth and fifth links is driven by rotation of the ladle-carrying motor so as to carry the ladle;a parallel linkage constituted by the first rotor, the pair of the first bar links and the second rotor and a parallel linkage constituted by the third rotor, the pair of the second bar links and the fourth rotor are driven by rotation of the ladle-rotating motor so as to rotate the ladle; andthe ladle can be kept in a predetermined posture by the two parallel linkages even if the five-bar linkage has any posture when the ladle-rotating motor is being stopped.

4. A molten metal supply device according to claim 3, wherein each pair of the first bar links and the second bar links are attached to their corresponding rotors with a phase difference of 90 degrees from each other.

5. A molten metal supply device according to claim 4, wherein at least one end portion of each of the pair of the first bar links and the pair of the second bar links is formed into a curved shape so as to avoid interference with the ladle-rotating output shaft, the first spindle or the second spindle.