Hot water supply equipment and hot water supply method

Abstract

To reduce a load on a motor for ladle transport in response to fluctuations in a torque curve with no particular restriction on selection of a speed reduction mechanism.SOLUTION: A hot water supply device 1 comprises a ladle 4, a transportation part 5 configured to be able to transport the ladle 4 to a supply destination, a drive part 10 configured to be able to drive the transportation part 5, and a casing 6 as a support part supporting the drive part 10 and the transportation part 5. The drive part 10 comprises a main motor 11 that mainly bears a necessary torque Tr required for transportation of the ladle 4 by the transportation part 5, a sub motor 12 that is a servo motor having a smaller capacity than that of the main motor 11 and bearing a necessary torque Tr together with the main motor 11, a drive shaft 10D that is rotated by a torque outputted from the main motor 11 and the sub motor 12 to drive the transportation part 5, and the drive circuit part 122 configured to enable servo-lock control of the sub motor 12.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a hot water supply system and a hot water supply method. [Background technology]

[0002] To supply molten metal used in casting, for example, to the injection sleeve of a die-casting machine, a molten metal supply system is used that pumps the molten metal from the furnace using a ladle and transports it to the destination. The ladle is transported from the furnace to the destination by a transport mechanism that includes a motor, a reduction gear, and a link-type arm that supports the ladle.

[0003] The capacity of the transport motor that delivers the molten metal ladle to the supply destination is selected according to the ladle's carrying capacity. Conventionally, large molten metal supply systems with high carrying capacity are equipped with counterweights on the arms to reduce the load on the transport motor. Since the procurement cost of high-capacity motors is extremely high, counterweights are used to limit the motor capacity. However, the installation of counterweights increases the external dimensions and operating range of the device, thus restricting the placement of surrounding equipment to avoid interference with the counterweights. Furthermore, the increased inertial force makes movement control difficult.

[0004] To reduce the load on the transport motor, in addition to counterweights, springs, dampers, etc., are used. For example, the motor load reduction device for an automatic water heater described in Patent Document 1 includes a worm gear (worm and worm wheel) and a torsion coil spring provided on the drive shaft that drives the water heater arm. Such a load reduction device does not include a counterweight.

[0005] The torque required for ladle transport changes throughout the transport process. According to Patent Document 1, a positive or negative torque is required based on the axial angle of 100 degrees, which is the angle at which the hot water supply arm is in a balanced state and the torque required for transport becomes zero. The torsion coil spring generates torque in the opposite direction to the load direction of the transport motor, based on the 100 degrees at which it is in a free state. In other words, the torque generated by the twisting of the torsion coil spring reduces the torque required for the transport motor. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Publication number 7-23096 [Overview of the project] [Problems that the invention aims to solve]

[0007] When using counterweights, springs, dampers, etc., to reduce the load on the transport motor that drives the arm of a hot water supply system, it is necessary to appropriately design the motor, reduction gear, and mechanical elements such as springs as load reduction means based on the torque characteristics required for transporting a ladder of a predetermined carrying capacity. In order to reduce the motor load using the torsion coil spring described in Patent Document 1, it is a requirement that the torque characteristics (torque curve) with respect to the angle of the drive shaft of the hot water supply arm remain constant.

[0008] However, the torque curve fluctuates due to changes in the load capacity (such as replacing the ladle), adjustments to the ladle's transport trajectory (such as changing the lever ratio of the link mechanism), or changes to the reduction gear. If the torque curve fluctuates, even if torque is generated by the torsion coil spring described in Patent Document 1, it is not necessarily possible to reduce the motor load. According to one calculation of changing the lever ratio of the link mechanism described in Patent Document 1, the motor load increases over a predetermined axial angle range.

[0009] Furthermore, since the torsion coil spring described in Patent Document 1 is installed between the worm wheel and the casing of the drive mechanism, the load reduction device described in Patent Document 1 must employ a worm gear as the reduction mechanism.

[0010] The present invention aims to provide a hot water supply device and a hot water supply method that do not impose any particular restrictions on the selection of a reduction mechanism used with a ladle transport motor, and that can reduce the load on the ladle transport motor in response to fluctuations in the torque curve. [Means for solving the problem]

[0011] The present invention relates to a molten metal supply device for supplying molten metal to a destination, comprising: a ladle configured to draw molten metal from a furnace and inject it into the destination; a transport unit configured to transport the ladle to the destination; a drive unit configured to drive the transport unit; and a support unit that supports the drive unit and the transport unit. The drive unit comprises a main motor that primarily bears the necessary torque required for the conveying of the rudder by the conveying unit, a sub-motor which is a servo motor with a smaller capacity than the main motor and bears the necessary torque together with the main motor, a drive shaft which is rotated by the torque output from the main motor and the sub-motor to drive the conveying unit, and a drive circuit unit configured to enable servo lock control of the sub-motor.

[0012] The present invention relates to a hot water supply method for supplying molten metal to a destination using a hot water supply device configured to transport a ladle, wherein, according to a torque curve corresponding to the ladle transport process, the required torque for transporting the ladle is mainly borne by the main motor, and the required torque is also borne by a sub-motor, which is a servo motor with a smaller capacity than the main motor, and in a certain region of the torque curve, a portion of the required torque is borne by the sub-motor through servo lock control. [Effects of the Invention]

[0013] According to the present invention, by apportioning the required torque for ladle conveyance between the main motor and the sub-motor capable of servo-lock control, and suppressing the required torque by the holding torque of the servo-lock control, it is possible to reduce the load and suppress the capacity of the main motor without providing a counterweight, a spring, or the like. By doing so, it is possible to reduce the procurement cost as a whole of the main motor, the sub-motor, and the reduction gear mechanisms associated therewith, compared to the procurement cost of the motor when the required torque is borne by only one motor, and to suppress the size of the water heater by miniaturizing the motor and the reduction gear mechanisms.

[0014] According to the present invention, it is possible to achieve a reduction in the load of the motor without the need to provide a counterweight, a spring, a damper, or the like, which have conventionally been used to reduce the load. Therefore, it is possible to provide a compact water heater by avoiding an increase in size due to providing load reduction means such as a counterweight and a spring. If the water heater is compact, peripheral equipment can be easily arranged adjacent to the water heater.

[0015] According to the electrical control by the sub-motor as a servo motor, different from the mechanical force by a counterweight, a spring, or the like, it is possible to appropriately control the output torque of the drive unit with respect to the required torque over an appropriate position range in the ladle conveyance process. Therefore, even if the curve of the required torque fluctuates due to a change in the locus of the displacement of the conveyance unit, a change in the design of the lever ratio, an increase or decrease in the portable weight, or the like, it is possible to reduce the load. According to the present invention, in the torque curve, only the required torque in the region where the load is desired to be reduced can be reduced without affecting other regions.

[0016] Furthermore, according to the present invention, there is no need to employ a worm gear as a reduction mechanism, thus avoiding the drawbacks that occur when a worm gear is used in the drive unit of a molten metal supply device. For example, even if the operation of the conveying unit becomes uncontrollable and the conveying unit continues to descend and becomes submerged in the molten metal in the furnace, and is stopped by a mechanical stopper, unlike when a worm gear self-locks (automatically tightens), the conveying unit and the ladle can be pulled out of the molten metal in the furnace by releasing the brake of the main motor. [Brief explanation of the drawing]

[0017] [Figure 1] This is a front view of a hot water supply system according to an embodiment of the present invention. [Figure 2] Figures (a) to (d) show the process by which the ladle is transported toward the supply destination in front by the operation of the link mechanism that constitutes the transport section. [Figure 3] This is a schematic side view of a hot water supply system. [Figure 4] This is a schematic diagram of the drive unit that drives the conveying section that supports the ladle. [Figure 5] This graph shows the torque characteristics (torque curve) required for the ladle's transport process throughout the ladle's conveying process. [Figure 6] This graph shows the overload characteristics of the sub-motor. [Modes for carrying out the invention]

[0018] One embodiment of the present invention will be described below with reference to the attached drawings. [Overall structure] The molten metal supply device 1 shown in Figure 1 supplies molten metal used in casting to, for example, an injection sleeve in the injection device of a die-casting machine. The molten metal supply device 1 uses a ladle 4 to draw out molten metal 3 stored in the furnace 2 schematically shown in Figure 1 and transports it to the location of the pouring opening of the injection sleeve (not shown), which is the supply destination. The hot water supply device 1 in this embodiment corresponds to a large-scale hot water supply device with a large weight (carrying capacity) of molten metal 3 that can be transported by the ladle 4.

[0019] Molten metal 3 corresponds to a metal in a molten state, such as an aluminum alloy, zinc alloy, magnesium alloy, or copper alloy. Furnace 2 corresponds to a holding furnace that maintains the molten metal 3 in a molten state, or a melting and holding furnace that melts metal and maintains it in a molten state.

[0020] The hot water supply device 1 comprises a ladle 4, a transport unit 5 configured to transport the ladle 4 to the supply destination, a drive unit 10 configured to drive the transport unit 5, a casing 6 as a support unit for supporting the drive unit 10 and the transport unit 5, a tilting motor (not shown) for tilting the ladle 4, and a hot water level detection sensor 7 configured to detect the hot water level 3A.

[0021] [Configuration and operation of the conveying unit] The transport unit 5 includes a link mechanism 5L provided on the drive shaft 10D of the drive unit 10, as shown in an example configuration in Figure 1. The drive shaft 10D is arranged horizontally. The link mechanism 5L consists of a plurality of links 50 to 54. Preferably, one end 501 of the drive link 50 is integrally mounted on the drive shaft 10D, which is fixed to the casing 6. In this specification, “integrally mounted” does not mean only being integrally formed. “Integrated mounted” also includes, for example, being integrally assembled by a key and keyway. The other end 502 of the drive link 50 is connected to the first link 51 by joint J0.

[0022] A second link 52 is connected to one end of the first link 51 by a joint J1, and this second link 52 is connected to a third link 53 by a joint J2. Joint J2 is fixed to the casing 6. The link mechanism 5L is fixed to the casing 6 at two points: the position of the drive shaft 10D and the position of joint J2.

[0023] The fourth link 54 is connected to the third link 53 by joint J3 and to the first link 51 by joint J4. Joint J0 is positioned between joint J1 and joint J4. The fourth link 54 extends linearly from joint J3 beyond the position of joint J4. The tip 541 of the fourth link 54 supports the ladder 4 so that it can tilt around the tilt axis 42.

[0024] The molten metal level detection sensor 7 includes detection rods 71 ​​and 72 as a pair of conductors to which a voltage is applied. The pair of detection rods 71 ​​and 72 are arranged along the fourth link 54 and supported by the fourth link 54. When the transport unit 5 descends toward the molten metal 3 in the furnace 2 and the lower ends of the detection rods 71 ​​and 72 come into contact with the molten metal 3, current flows through the closed circuit formed by the detection rods 71 ​​and 72 and the molten metal 3, making it possible to detect the position of the molten metal level 3A. The entry depth of the ladle 4 can be determined relative to this position of the molten metal level 3A. Furthermore, the molten metal level detection sensor 7 is not limited to one that detects the molten metal level 3A by contact with the molten metal 3, but may also be a non-contact type sensor configured to detect the molten metal level 3A using a laser or the like.

[0025] The drive link 50 rotates around the drive shaft 10D due to the torque transmitted to the drive shaft 10D by the drive unit 10. When the drive link 50 rotates clockwise in the direction D1 shown in Figure 1, the ladle 4 supported by the conveying unit 5 descends and retracts toward the furnace 2. Figure 1 shows the conveying unit 5 at its retraction limit RL. When the drive link 50 rotates counterclockwise in the direction D2, the ladle 4 rises and advances toward the molten metal supply destination.

[0026] The transport unit 5 and the ladle 4 operate, for example, as follows, based on commands sent from, for example, the control device of the die-casting machine to the drive unit 10 and the tilting motor. As shown in Figure 1, the ladle 4 is tilted clockwise in the direction d1 at the retraction limit RL, and after the ladle 4 enters the molten metal 3 in the furnace 2, the ladle 4 is tilted counterclockwise in the direction d2, thereby scooping out an amount of molten metal 3 corresponding to the product to be cast using the ladle 4.

[0027] Subsequently, as shown in Figures 2(a) to 2(d) for the transport process of the ladle 4 by the transport unit 5, the ladle 4 is transported to its forward limit FL (position in Figure 2(d)) while displacing the link mechanism 5L in accordance with the rotation of the drive link 50. Then, when the ladle 4 is tilted in a counterclockwise direction d2 at the pouring position at the supply destination (for example, above the pouring opening of the injection sleeve), molten metal is injected from the spout 41 into, for example, the inside of the injection sleeve.

[0028] [Configuration of the drive unit] The configuration of the drive unit 10 will be described with reference to Figures 1, 3, and 4. The drive unit 10 comprises a main motor 11, a sub-motor 12, a reduction unit 13, and a drive shaft 10D. All of these are located in the casing 6. As shown in Figure 1, when the casing 6 is viewed along the axial direction of the drive shaft 10D (front view I), the transport unit 5 is located on the drive shaft 10D on the front side 6F of the casing 6. On the other hand, the output shaft 11A of the main motor 11 and the output shaft 12A of the sub-motor 12 are located on the rear side 6B of the casing 6, as shown in Figure 3, and their output shafts 11A and 12A are arranged parallel to each other.

[0029] (Main motor) The main motor 11 provides the torque required for conveying the ladder 4 (required torque T). r The main motor 11 is, for example, an induction motor to which three-phase alternating current is applied, and comprises a motor body 110, a reduction gear 111 (gearhead) connected to a shaft (not shown) of the motor body 110, an output shaft 11A, a drive circuit section 112, and an electromagnetic brake 113. If the main motor 11 is a general-purpose motor and the rotation angle of the drive link 50 is to be obtained, an encoder (not shown) is provided on the drive shaft 10D. If the main motor 11 is a servo motor, the rotation angle of the drive link 50 can be obtained using the encoder provided on the main motor 11.

[0030] The motor body 110 includes a stator and rotor (not shown) and a case 11C. The reduction gear 111 includes a gear train (not shown). The output shaft 11A is arranged parallel to the axis of the motor body 110.

[0031] The electromagnetic brake 113 is configured to activate when the molten metal level 3A is detected by the molten metal level detection sensor 7. The control to stop the descent of the conveying unit 5 after the ladle 4 has entered the furnace 2 is triggered by the detection signal from the molten metal level detection sensor 7. At this time, if the power supply to the electromagnetic brake 113 is cut off by a command from, for example, the control device of the die-casting machine, the electromagnetic brake 113 will activate immediately.

[0032] Furthermore, if the power supply to the main motor 11 is cut off due to a malfunction in the drive circuit 112 or other components, the electromagnetic brake 113 will immediately activate. This prevents the transport unit 5 from free-falling in the event of a malfunction.

[0033] In other words, the electromagnetic brake 113 is of the de-excitation type, and although detailed illustrations are omitted, it comprises, for example, a brake stator fixed to the case 11C, a brake armature, and a spring member. When the power supply to the coil of the brake stator is stopped and it is de-excited, the brake armature is pressed against the rotor by the spring member, and the lining on the surface of the brake armature comes into close contact with the rotor. At this time, the rotation of the rotor is braked by the frictional force between the lining and the rotor. While the coil of the brake stator is energized, the brake armature is attracted to the brake stator by magnetic force, overcoming the elastic force of the spring member. At this time, the electromagnetic brake 113 is released, and the rotor is rotatable.

[0034] An AC power supply and drive circuit unit 112 (not shown) supply current to the stator coil according to the load on the main motor 11, causing the rotor to rotate and torque to be output from the motor body 110. This torque increases based on the reduction ratio corresponding to the gear ratio of the gear train of the reduction gear 111, and is output from the output shaft 11A and transmitted to the drive shaft 10D. Preferably, the output shaft 11A is integrally provided with the drive shaft 10D.

[0035] Furthermore, instead of the main motor 11 and reduction gear 111, a geared motor with a gear train built into the case 11C as a reduction mechanism can be used as the main motor. The same applies to the sub-motor 12.

[0036] (Sub-motor) Next, the sub-motor 12, together with the main motor 11, provides the required torque T. r The sub-motor 12 has a smaller capacity than the main motor 11. This sub-motor 12 corresponds to a servo motor configured to control at least position among position, speed, and torque.

[0037] The sub-motor 12 is, for example, an induction motor to which a three-phase alternating current is applied, and comprises a motor body 120, a reduction gear 121 (gearhead) connected to a shaft (not shown) of the motor body 120, an output shaft 12A, an encoder 12E and a torque sensor 12T, and a drive circuit unit 122.

[0038] The motor body 120 includes a stator and rotor (not shown) and a case 12C. The reduction gear 121 includes a gear train (not shown). The output shaft 12A is arranged parallel to the axis of the motor body 120.

[0039] A current corresponding to the load on the sub-motor 12 flows through the stator coil via an AC power supply and drive circuit 122 (not shown), causing the rotor to rotate and torque to be output from the motor body 120. This torque increases based on the reduction ratio corresponding to the gear ratio of the gear train of the reduction gear 121 and is output from the output shaft 12A. The output torque of the sub-motor 12 is further increased by the reduction unit 13 and transmitted to the drive shaft 10D.

[0040] (Drive circuit section) The drive circuit 122 detects the rotational position of the output shaft 12A using the encoder 12E and performs position control such as feedback control. In this embodiment, the drive circuit 122 can perform position control by position detection using the encoder 12E, and torque control using the torque sensor 12T.

[0041] The drive circuit unit 122 is equipped with a servo lock control function. Servo lock control refers to the attempt to hold the servo motor at a stopping position (target position) by position control. When the position of the sub-motor 12 is shifted by an external force from the target position, which is the starting position of servo lock control, the drive circuit unit 122 applies current to the stator coil to resist the external force and output a holding torque to hold it at the target position in an attempt to return it to the target position.

[0042] In this embodiment, the servo lock control of the sub-motor 12 is performed using the required torque T. r This is done to have the sub-motor 12 bear part of the load. In this case, the external force is the torque output from the main motor 11 that is transmitted to the output shaft 12A via the drive shaft 10D, the second gear 132, and the first gear 131.

[0043] Furthermore, it is preferable that the drive circuit section 122 is equipped with a torque limiting function that sets an upper limit for the output torque. The torque limiting function makes it possible to accommodate increases or decreases in the carrying capacity due to replacement of the ladle 4, etc. When increasing the carrying capacity, there is no need to add a counterweight to the conveying section 5 as in the conventional method; the upper limit for the output torque can be increased in proportion to the increase in the carrying capacity.

[0044] (Reduction unit) As shown in FIG. 4 which shows an example of the configuration, the reduction unit 13 includes a first gear 131 provided integrally with the output shaft 12A of the sub-motor 12, and a second gear 132 provided integrally with the output shaft 11A and the drive shaft 10D of the main motor 11. Both the first gear 131 and the second gear 132 are, for example, spur gears, and are provided inside the casing 6 in a meshed state. Inside the casing 6, bearings (not shown) for supporting the output shafts 11A, 12A and the drive shaft 10D are also provided.

[0045] If the number of teeth of the first gear 131 is n1 and the number of teeth of the second gear 132 is n2, then n1 < n2. The gear ratio between the first gear 131 and the second gear 132 is 1:(n2 / n1), and the reduction ratio corresponds to 1 / (n2 / n1). Then, the torque output from the output shaft 12A basically increases by (n2 / n1) times.

[0046] The output shaft 11A and the output shaft 12A are arranged in parallel on the back side 6B of the casing 6 via the reduction unit 13. In this case, since the two motors 11 and 12 are installed on the same side (the back side 6B) of the casing 6, it contributes to reducing the space for installing the motors 11 and 12. The reduction unit 13 is not an essential component of the drive unit 10. However, when the drive unit 10 does not include the reduction unit 13, for example, the output shaft 11A of the main motor 11 provided on the back side 6B of the casing 6 is connected to one end of the drive shaft 10D, and the output shaft 12A of the sub-motor 12 provided on the front side 6F of the casing 6 is connected to the other end of the drive shaft 10D. Therefore, the drive unit 10 becomes thicker in the direction of the drive shaft 10D. Moreover, if either one of the motors 11 and 12 is installed on the front side 6F of the casing 6, for example, as shown in FIGS. 2(c) and (d), a part (the third link 53 or the fourth link 54) of the conveying unit 5 interferes with the motor installed on the same axis as the drive shaft 10D. To avoid this, the hot water supply device 1 including the conveying unit 5 becomes even thicker.

[0047] Since there are no particular constraints on the mechanism of the reduction gear 13, the design freedom of the reduction gear 13 is high. For example, the first gear 131 and the second gear 132 may be helical gears. The reduction gear 13 may also include one or more intermediate gears capable of transmitting torque between the first gear 131 and the second gear 132. In order to reduce the capacity of the motors 11 and 12 connected to the reduction unit 13, it is preferable that the efficiency of the reduction unit 13 be as high as possible. Also, in order to reduce the size of the casing 6, it is preferable that the gear train of the reduction unit 13 be arranged as compactly as possible. Here, a configuration in which the arrangement of the main motor 11 and sub-motor 12 is reversed from that of this embodiment is also permissible, that is, a configuration in which the sub-motor 12 is mounted on the drive shaft 10D and the main motor 11 transmits torque to the drive shaft 10D via the reduction unit 13. However, in that case, the reduction unit 13 requires a gear with a larger module. This is because a gear with a larger module suitable for the large torque transmitted from the main motor 11 to the sub-motor 12 is required. In this case, due to the gear ratio relationship, the relationship between the size of the gear diameters is reversed. That is, a large-diameter gear is placed in the position of the first gear 131 in this embodiment, and a small-diameter gear is placed in the position of the second gear 132 in this embodiment. From the viewpoint of minimizing the gear size of the reduction gear 13 and thereby reducing gear cost and backlash, the configuration in this embodiment, in which the output shaft 11A of the main motor 11 is provided on the drive shaft 10D and the sub-motor 12 is connected to the drive shaft 10D via the reduction gear 13, is advantageous. In this embodiment, the reduction gear 13 distributes the required torque T from the first gear 131 to the second gear 132, with the majority of the load borne by the main motor 11. r Since they transmit the remaining torque, the modules of the first gear 131 and the second gear 132 are small.

[0048] The reduction gear 13 may include a bevel gear (e.g., a miter gear). For example, if the output shaft of the motor body 110 is positioned vertically, the torque rotating around the vertical axis may be converted into torque rotating around the horizontal axis via the miter gear and transmitted to the drive shaft 10D. Note that it is preferable to avoid adopting a worm gear as the mechanism of the speed reduction unit 13 for the reasons described later.

[0049] The speed reduction unit 13 is lubricated by an appropriate method. As the lubrication method, it is preferable to adopt a grease lubrication method using grease, or a forced lubrication method such as dropping, injecting, or spraying lubricating oil. Such lubrication methods are more suitable for use in a high-temperature environment near the furnace 2 than the oil bath lubrication method adopted for worm gears.

[0050] 〔Torque characteristics required for ladle conveyance and selection of motor corresponding thereto〕 The required torque T required for conveying the ladle 4 r is, for example, as shown in an example of the torque curve of the required torque T r corresponding to the rotation angle θ of the drive link 50 in FIG. 5, and changes throughout the conveyance process. The torque curve shown in FIG. 5 is based on analysis and calculation. FIG. 5 shows the required torque T required for conveying the ladle 4 containing molten metal throughout the conveyance process of conveying the ladle 4 from the retraction limit RL to the forward limit FL. r Shown. (a) shown in FIG. 5 corresponds to (a) of FIG. 2. The same applies to (b) and (d).

[0051] The required torque T r balances with the torque output to the drive shaft 10D during the conveyance process and becomes "0". In FIG. 5, the rotation angle θ0 at which the drive link 50 coincides with the vertical direction as shown in FIG. 2(b) is used as a reference. In the torque curve shown in FIG. 5, the required torque T r has a positive value in the counterclockwise direction D2 as viewed from the output shafts 11A and 12A (for example, between (a) and (b)), and a negative value in the clockwise direction D1 as viewed from the output shafts 11A and 12A, such as on the retraction limit RL side rather than (a). The required torque T r on the retraction limit RL side is relatively larger in absolute value than the required torque T r on the forward limit FL side. Here, on the reverse limit RL side compared to (a), the required torque T increases as the absolute value of the rotation angle θ increases with respect to the reference rotation angle θ0. r It increases. In other words, the required torque T r The peak torque (hereinafter referred to as peak torque P1) is at the retraction limit RL.

[0052] When selecting a motor, consider the required torque T. r The load and motor capacity must be considered. While various motors exist, generally speaking, the larger the motor capacity, the higher the procurement cost. In particular, for motors with a capacity of 5kW or more, the procurement cost increases exponentially with respect to capacity. Therefore, in this embodiment, the required torque T r As the main motor 11 primarily responsible for this task, we selected a motor with the highest possible rated torque within a realistic cost range, while also considering the required torque T r The deficiency is compensated for by the sub-motor 12. Here, a servo motor is used as the sub-motor 12 in order to keep the sub-motor 12 to the minimum necessary capacity by utilizing the holding torque by servo lock control. This servo motor can be an inexpensive motor with a capacity that is sufficiently smaller than that of the main motor 11. When selecting the main motor 11, for example, the required torque T r The ratios of the average value and peak value to the rated value are set so that the average value and peak value are below the rated torque of the main motor 11.

[0053] Required Torque T r The deficit corresponds, for example, to region 12R (servo lock control region) in the torque curve shown in Figure 5, which includes the peak torque P1. Servo lock control of the sub-motor 12 is performed throughout this region 12R. As a result, the sub-motor 12 generates a holding torque while reducing the rotational speed of the first gear 131 and the second gear 132, in opposition to the rotation of the drive shaft 10D from which the torque of the main motor 11 is output. rThe absolute value of decreases, for example, as shown by the dashed line in Figure 5. Peak torque P1 changes to peak torque P2. The fluctuation in the value in the servo lock control region 12R is due to the inertial torque when operating the transport unit 5.

[0054] [Example of calculation for required capacity, etc.] For example, the rated torque of the sub-motor 12 can be used to support the torque of the main motor 11. An example of calculations regarding capacity, torque, and reduction ratio when using a single motor versus when using both the main motor 11 and the sub-motor 12 is shown. <Main motor proposal 1> Capacity: 8kW Rated torque: 75 N·m Reduction ratio: 1 / 220 Motor torque: 75 × 220 = 16500 [N·m]

[0055] <Main motor proposal 2> Capacity: 6kW Rated torque: 57 N·m Reduction ratio: 1 / 220 Motor torque: 57 × 220 = 12540 [N·m]

[0056] <Torque reduction value due to sub-motor> The following conditions were assumed. Sub-motor rated torque: 10 N·m Reduction ratio: 1 / 100 Reduction ratio by the first and second gears: 1 / 5 Torque reduction value: 10 × 100 × 5 = 5000 [N·m]

[0057] If only one motor is used, assuming a peak torque P1 of 16,000 N·m, an 8kW motor would be required, as in Main Motor Option 1. However, when using both the main motor 11 and the sub-motor 12 as in this embodiment, taking into account the torque reduction due to the sub-motor 12, the peak torque P2 becomes 16,000 - 5,000 = 11,000 [N·m], allowing the use of a 6kW motor, one size smaller than the 8kW motor. Based on the correlation between motor capacity and procurement cost, reducing the capacity from 8kW to 6kW significantly lowers costs. The required torque T is due to the large load capacity. r The larger the value, the greater the cost benefits from reducing motor capacity. For example, reducing capacity from 8kW to 6kW can lower costs significantly more than reducing it from 3.7kW to 2.2kW.

[0058] Figure 6 is a graph showing the overload characteristics of the sub-motor 12. The horizontal axis represents the load factor of the sub-motor 12, and the vertical axis, which is a logarithmic scale, represents the time required until an abnormality occurs during continuous operation. The solid line L1 shows the overload characteristics when servo lock control is not performed, and the dashed line L2 shows the overload characteristics when servo lock control is performed. In the region 12R described above, the sub-motor 12 is subjected to a load exceeding its rated torque. However, the time corresponding to the rotation angle range of region 12R is shorter than the time allowed based on the overload characteristics of the sub-motor 12. Therefore, servo lock control of the sub-motor 12 is required under torque T r This is performed only in region 12R, and servo lock control is not performed in the remaining region, thereby preventing malfunctions of the sub-motor 12 and avoiding placing unnecessary loads on the main motor 11.

[0059] [Effects of this embodiment] The main effects of this embodiment are listed below. Torque T required for conveying Laddle 4 rIn contrast, the capacity of the main motor 11 is kept low, while the minimum necessary capacity is supplied to the sub-motor 12, which is capable of servo lock control, thereby supplying the required torque T to both motors 11 and 12. r By having the load borne by the drive unit 10, for example, a drive unit 10 that drives a large hot water heater 1 with a carrying capacity of 50 to 100 kg or more can reduce the load without having to equip it with counterweights or springs. As a result, it becomes possible to reduce the capacity of the main motor 11 and lower the reduction ratio of the reduction gear 111 of the main motor 11. Then, the required torque T r Compared to the procurement cost of a motor when the load is handled by only one motor, it is possible to reduce the overall procurement cost of the main motor 11, sub-motor 12, and reduction unit 13, and the size of the hot water supply device 1 can be reduced by miniaturizing the motor 11 and reduction unit 111.

[0060] According to this embodiment, it is possible to provide a compact hot water supply device 1 by avoiding the need for a counterweight that expands the operating range, or for springs, dampers, or worm gears that tend to increase the thickness of the casing 6 in the direction of the drive shaft 10D. If the hot water supply device 1 is compact, peripheral equipment such as devices necessary for cleaning molds or applying release agents to molds (e.g., spray devices) and a work floor can be easily placed adjacent to the hot water supply device 1, and it also contributes to reducing packaging and transportation costs for the hot water supply device 1.

[0061] Electrical control by the sub-motor 12 acting as a servo motor, unlike mechanical forces such as counterweights and springs, allows the output torque of the drive unit 10 to be controlled over an appropriate angular range during the transport process of the ladle 4, thereby achieving the required torque T. r This allows for proper control of the required torque T due to changes in the displacement trajectory of the link mechanism 5L, changes in the lever ratio design, increases or decreases in the load capacity, etc. r Even if the curve fluctuates, it becomes possible to reduce the load.

[0062] When a torsion coil spring is used as a load reduction means, as in Patent Document 1, depending on the lever ratio of the link mechanism, it is possible that the load may be reduced in the region on the backward limit RL side of the torque curve, but the load may increase in the region on the forward limit FL side. In contrast, according to this embodiment, the required torque T in the region 12R where the load reduction is to be desired is r This allows for reduction in only that area without affecting other areas.

[0063] In Patent Document 1, a worm gear is used to install a torsion coil spring. However, worm gears are unsuitable for the hot water supply device 1, particularly due to the following reasons caused by self-locking (they do not rotate from the output side). If the operation of the transport unit 5 is uncontrollable and the drive link 50 continues to rotate due to the output torque from motors 11 and 12 at the retraction limit RL position, the fourth link 54 of the transport unit 5, which has inferior heat resistance compared to the ladle 4, will be submerged in the molten metal 3 in the furnace 2. In this case, if a worm gear is used in the reduction unit 13, rotation cannot be transmitted from the worm wheel side to the worm, so the fourth link 54 and the ladle 4 will remain submerged in the molten metal 3 in the furnace 2. In other words, unless the worm rotates due to the rotation of motors 11 and 12, the fourth link 54 and the ladle 4 cannot be pulled out of the molten metal 3.

[0064] As in this embodiment, if a worm gear is not used in the reduction unit 13, even if the rotation of the motors 11 and 12 stops due to an emergency stop, the electromagnetic brake 113 can be manually released, and the fourth link 54 and the ladle 4 can be manually pulled out of the molten metal 3 in the furnace 2.

[0065] In addition to the above, it is possible to select or replace the configurations listed in the above embodiments, or to change them to other configurations as appropriate, as long as it does not deviate from the spirit of the present invention. The transport unit 5 is not limited to a closed-link type as in the above embodiment, but may also include, for example, a first arm that is driven by a first motor and is swingable, and a second arm that is supported by the first arm and is driven by a second motor and is swingable, as disclosed in Japanese Patent Application Publication No. 2020-157356.

[0066] [Note] From the above disclosures, the following configuration can be understood. (1) A hot water supply device that supplies molten metal to a recipient, A ladle configured to draw the molten metal from the furnace and inject it into the supply destination, A conveying unit configured to transport the aforementioned ladle to the supply destination, A drive unit configured to drive the transport unit, The drive unit and the transport unit are supported by a support unit, The aforementioned drive unit is The main motor primarily bears the necessary torque required for the conveying of the ladder by the conveying unit, A servo motor comprising a sub-motor with a smaller capacity than the main motor and which together with the main motor bears the required torque, A drive shaft that is rotated by the torque output from the main motor and the sub-motor to drive the transport unit, The system includes a drive circuit section configured to enable servo lock control of the sub-motor, Hot water supply system.

[0067] (2) The servo lock control causes a portion of the required torque to be borne over a portion of the torque curve corresponding to the conveying process of the rudder, The hot water supply device according to (1), wherein the servo-lock control region as a part of the region includes the peak torque in the torque curve.

[0068] (3) The hot water supply device according to (2), wherein in the servo lock control region, a load greater than or equal to the rated torque is applied to the sub-motor for a period of time shorter than the time permitted based on the overload characteristics of the sub-motor.

[0069] (4) The output shaft of either the main motor or the sub-motor is integrally mounted with the drive shaft. The hot water supply device according to any one of (1) to (3), wherein the drive unit includes a reduction unit that increases the torque output from the other of the main motor and the sub-motor based on a predetermined reduction ratio and transmits it to the drive shaft.

[0070] (5) The reduction unit is The system includes a first gear on which the output shaft of the sub-motor is integrally mounted, and a second gear on which the output shaft of the main motor and the drive shaft are integrally mounted, The hot water supply device according to (4), wherein the torque output from the sub-motor is transmitted to the drive shaft via the first gear and the second gear.

[0071] (6) The transport unit is provided on the drive shaft on the front side of the support when the support unit is viewed in the axial direction of the drive shaft, The hot water supply device according to (4) or (5), wherein the output shaft of the main motor and the output shaft of the sub-motor, which are connected via the reduction gear, are arranged parallel to each other on the rear side of the support portion.

[0072] (7) The hot water supply device according to any one of (1) to (6), wherein the main motor and the sub-motor are each equipped with a reduction mechanism.

[0073] (8) A molten metal level detection sensor configured to detect the molten metal level in the furnace is provided, The hot water supply device according to any one of (1) to (7), wherein the main motor is equipped with an electromagnetic brake configured to operate when the water level is detected by the water level detection sensor.

[0074] (9) A hot water supply method for supplying molten metal to a destination using a hot water supply device configured to transport a ladle, In accordance with the torque curve corresponding to the ladle transport process, the required torque for transporting the ladle is mainly borne by the main motor, and the required torque is also borne by a sub-motor, which is a servo motor with a smaller capacity than the main motor. A hot water supply method wherein, in a certain region of the torque curve, a portion of the required torque is borne by the servo lock control provided in the sub-motor.

[0075] (10) The servo lock control region as a part of the region includes the peak torque in the torque curve, The hot water supply method according to (9), wherein in the servo lock control region, a load greater than or equal to the rated torque is applied to the sub-motor for a period of time shorter than the time permitted based on the overload characteristics of the sub-motor.

[0076] (11) Torque is transmitted to the drive shaft that drives the conveying section supporting the ladle from one of the output shafts of the main motor and the sub-motor, which is integrally provided with the drive shaft, Torque is transmitted to the drive shaft from the other of the output shafts of the main motor and the sub-motor via a reduction unit that increases the torque based on a predetermined reduction ratio. The hot water supply method described in (9) or (10).

[0077] (12) The hot water supply method according to any one of (9) to (11), wherein the torque limit value provided in the sub-motor is adjusted in accordance with an increase or decrease in the carrying capacity of the ladle, or a change in the lever ratio of the link mechanism constituting the transport section that supports the ladle. [Explanation of Symbols]

[0078] 1. Hot water supply system 2 furnace 3. Molten metal 3A hot water surface 4 ladles 5. Conveying section 5L Linkage Mechanism 6. Casing (support part) 6B Rear side 6th floor, front side 7. Water level detection sensor 10 Drive unit 10D drive shaft 11 Main motor 11A output shaft 11C Case 12 Sub-motors 12A output shaft 12C Case 12E Encoder 12T Torque Sensor 12R region (servo lock control region) 13 Reduction section 41 Spout 42. Axis of tilt 50 Drive link 51 Link 1 52 Second Link 53 Third Link 54. Link 4 71, 72 detection rods 110 Motor body 111 Reducer (reduction mechanism) 112 Drive circuit section 113 Electromagnetic brake 120 Motor body 121 Reducer (reduction mechanism) 122 Drive circuit section 131 First gear 132 Second gear 501 One end of drive link 50 502 Other end of drive link 50 541 Tip D1, d1 clockwise direction D2, d2 counterclockwise direction FL forward limit RL Retraction limit J0~J4 Joint L1 Solid line L2 dashed line P1, P2 Peak Torque T r Required Torque θ Rotation angle θ0 Reference rotation angle

Claims

1. A hot water supply device that supplies molten metal to a recipient, A ladle configured to draw the molten metal from the furnace and inject it into the supply destination, A conveying unit configured to transport the aforementioned ladle to the supply destination, A drive unit configured to drive the transport unit, The drive unit and the transport unit are supported by a support unit, The aforementioned drive unit is The main motor primarily bears the necessary torque required for the conveying of the ladder by the conveying unit, A servo motor comprising a sub-motor with a smaller capacity than the main motor and which together with the main motor bears the required torque, The system includes a drive shaft that is rotated by the torque output from the main motor and the sub-motor to drive the transport unit, Hot water supply system.

2. By controlling the sub-motor, a portion of the required torque is borne over a certain region of the torque curve corresponding to the ladle's transport process. The sub-motor control region, as a part of the aforementioned region, includes the peak torque in the torque curve. The hot water supply device according to claim 1.

3. The hot water supply device according to claim 2, wherein in the sub-motor control region, a load greater than or equal to the rated torque is applied to the sub-motor for a period of time shorter than the time permitted based on the overload characteristics of the sub-motor.

4. The output shaft of either the main motor or the sub-motor is integrally mounted on the drive shaft. The drive unit includes a reduction unit that increases the torque output from the main motor and the other of the sub-motor based on a predetermined reduction ratio and transmits it to the drive shaft. A hot water supply device according to any one of claims 1 to 3.

5. The aforementioned deceleration unit is The output shaft of the sub-motor is integrally provided with the first gear, and the output shaft of the main motor The drive shaft is integrally mounted with a second gear, The torque output from the sub-motor is transmitted through the first gear and the second gear. Transmitted to the drive shaft, The hot water supply device according to claim 4.

6. A hot water supply method for supplying molten metal to a destination using a hot water supply device configured to transport a ladle, In accordance with the torque curve corresponding to the ladle transport process, the required torque for transporting the ladle is mainly borne by the main motor, and the required torque is also borne by a sub-motor, which is a servo motor with a smaller capacity than the main motor. A hot water supply method wherein, in a certain region of the torque curve, a portion of the required torque is borne by the control of the sub-motor.

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