Baglioni, Giuliano c/o Automazioni Industriali S.r.l. (Via Mainone 2-C-D-E, Lumezzane S.S., I-25065, IT)
| 1. | Device to support the cup (11) or ladle for the freefall casting of molten metal in shells performed by robots, where the robot is equipped with a wrist (10) with a fixed part (12) and a rotating terminal (13), and where the device comprises a shaft (15) fastened to said rotating part of the wrist, in which said device comprises a sensor (19) to measure the amount of metal in the ladle by measuring the flexion of the shaft (15) caused by the presence of metal in the same ladle. |
| 2. | Device according to claim 1, in which said sensor (19) is able to measure the differences in movement between a fairing (17) joined laterally to a fixed part (12) and a stretch of the shaft (15). |
| 3. | Supporting device according to claim 1 or 2, in which said sensor (19) has a fixed part (22) which is joined to the wrist of the robot, a mobile part (20) associated with the support device shaft and at least one torque meter (23) linking the mobile part with the fixed part and destined to measure the torque exercised by the first on the second following the flexion of the shaft. |
| 4. | Supporting device according to claim 3, in which the shaft (15) is inserted inside a fairing (17) joined to the fixed part 12 of the robot's wrist, and in which the fixed part of the sensor is anchored to the same fairing by way of a special support (18). |
| 5. | Supporting device according to claim 4, in which the mobile part of the sensor is made up of a central element (20) with an axial hole (20') in which it rests and which guides the shaft (15) with the insertion of a bearing (21), and in which the fixed part of the sensor is made up of two lateral elements (22), each fastened to the central element by a respective torque meter (23). |
| 6. | Supporting device according to any of the previous claims, in which the shaft is divided into two parts connected by an elastic joint (15') which compensates for any misalignment with the axis. |
| 7. | Device according to claim 1 or 2, in which a fairing (17) coupled with said fixed part (12) in a freely rotating way and cooperates with said sensor for the measurement of the movements of said stretch of shaft. |
| 8. | Supporting device according to claim 7, in which said sensor (19) comprises a central element (20) coupled with said shaft (15) in a freely rotating way. |
| 9. | Device according to claim 8, in which said sensor (19) comprises side elements (22) joined to the fairing (17) and cooperating with said central element (20). |
| 10. | Device according to claim 9, in which torque meters (23) are inserted between said central element (20) and said side elements (22). |
| 11. | Sensor to measure the flexion of a shaft comprising a central element (20) crossed axially by a hole in which said shaft is inserted and guided, two side elements (22) anchored to a fixed support, and two torque meters (23), each of which connects the central element to a side element and destined to measure the torque exercised by the first on the second following the flexion of the shaft. |
| 12. | Device according to claim 1, in which said shaft (15) is fastened to said rotating part of the wrist by a flange (14). |
| 13. | Device according to claim 1, in which said shaft ends in a flange (16) to which the ladle will be fastened in such a way as to remain mobile. |
[0002]. The use of robots to automate the pouring of molten metal from a bath, which can be either a furnace or a ladle, into a shell using the free-fall casting technique is quite common. The robots usually used are equipped with a rotating supporting device to which the ladle destined to collect the molten metal from the bath to pour it into the shell is fastened.
[0003]. One of the problems inherent in these automated casting operations in the determination of the exact amount of molten metal that must be collected by the ladle and poured into the shell, thus successfully creating the cast. This aspect is particularly critical especially when casting brass, as this metal tends to solidify and result in the formation of a crust on the bottom and on the walls of the ladle, which is altered, gradually reducing the amount of metal which can be transported by the same ladle and therefore the mass of molten metal poured into the shell with the same number
of pouring cycles. Obviously it is impossible to forecast the formation of this crust as it depends on the combination of a range of variables, making it difficult to work out the exact amount of molten metal to pour into the shell.
[0004]. The aim of this invention is to eliminate the abovementioned problem in automated free-fall casting systems and to present a device to support the ladle used to collect the molten metal that enables determination of the exact amount of metal in the ladle and therefore the precise control of the amount poured into the shell.
[0005]. Another aim of the invention is to supply a support for the molten metal collection ladle equipped with a sensor capable of measuring the amount of metal inside the ladle even when it is tipped to pour it out, allowing the modulation of the casting depending on the fluidity of the metal.
[0006]. These and other aims and advantages of the invention are achieved with a device to support the cup or ladle for the free-fall casting of molten metal into shells performed by robots, where the robot is equipped with a wrist with a rotating terminal, and where the device comprises a shaft fastened to said rotating part of the wrist by a flange, ending in another flange to which the ladle is fastened in such a way as to remain
mobile. There will be a sensor to measure the amount of metal in the ladle by measuring the flexion of the shaft caused by the presence of metal in the same ladle.
[0007]. The sensor has a fixed part which is joined to the robot, a mobile part associated with the support device shaft and at least one torque meter linking the mobile part with the fixed part and destined to measure the moment, or flexing moment, exercised by the first on the second following the flexion of the shaft.
[0008]. Further details of the invention will become more obvious with the description herein, with reference to the enclosed drawings, which are indicative and not binding, in which: [0009]. Fig. 1 shows the prospective view of the supporting device in question with a ladle mounted onto it; [0010]. Fig. 2 shows an axial section of the supporting device and ladle; [0011]. Fig. 3 shows the supporting device and ladle as seen from above; [0012]. Fig. 4 shows a prospective view of the torsion sensor mounted on the supporting device; [0013]. Fig. 5 shows a front view of the sensor shown in Fig. 4; [0014]. Fig. 6 shows the prospective view of the
supporting device in another version; [0015]. Fig. 7 shows the axial section of the device shown in Fig. 6; [0016]. Fig. 8 shows the device shown in Fig. 6 as seen from above; [00171. Fig. 9 represents a section of the device shown in Fig. 6 according to the B-B section line shown in Fig.
8.
[0018]. In these drawings, the number 10 is used to indicate the wrist of the robot for moving a ladle 11, destined for collecting the molten metal from a bath, which can be either a furnace or a ladle, into a shell using the free-fall casting technique-not shown here.
[0019]. The wrist 10 presents a fixed part 12 and a rotating terminal part 13 to which a shaft 15 is fastened by means of a flange 14. The shaft 15 ends in another flange 16 to which the ladle 11 is fastened in such a way as to be detachable.
[0020]. The shaft 15 can be divided into two parts connected by an elastic joint 15'which compensates for any misalignment with the axis. tO021]. The shaft 15 should preferably be inserted inside a fairing 17 which should preferably be joined to the fixed part 12 of the robot's wrist.
10022]. The shaft 15 is also inserted inside a fairing 17
joined to the fixed part 12 of the robot's wrist.
[0023]. In accordance with the invention, a sensor 19 associated with the shaft 15 and destined for measuring the amount of molten metal inside the ladle 11 is fastened to the fairing 17 by means of a suitable support 18. For this purpose, the sensor 19 is made up of a central element 20 with an axial hole 20'in which it rests and which guides the shaft 15, with the insertion of a bearing 21 and two lateral elements 22 fastened to the support 18, and of a pair of torque meters 23 that connect the central element 20 to the lateral elements 22.
[0024]. The term torque meter refers, in particular, to a sensor element equipped with a deformable portion (elasticated for instance) coupled with sensors which measure its flexion. These sensors can be distributed along the deformable elements in such a way as to accentuate the measurement of the flexion, compensating for the deformations induced by temperature changes where necessary.
[0025]. These torque meters 23 enable the rotation of the central element 20 around the fixed lateral elements 22 and measure the torque or the moment, in other words, the flexing moment, exercised by the first on the second. In particular, the presence of liquid metal in the ladle
causes a flexion of the shaft 15 and, consequently, a rotation of the central element 20 of the sensor associated with it.
[0026]. By using the torsion caused by a new ladle full of metal as the reference value, it is possible to obtain a relationship that precisely links the change in torsion from said reference value measured with the sensor with corresponding changes in the amount of liquid metal present in the ladle, due to the formation of a crust of solidified metal on the bottom and on the walls of the same ladle.
[0027]. It is therefore possible, regardless of the knowledge of the thickness of said crust and the number of casting cycles, to precisely determine the amount of molten metal poured into the shell.
[0028]. It is worth noting that the sensor 19 is also capable of measuring the amount of molten metal in the ladle while the latter is rotating to pour the metal into the shell. This enables, for example, the measurement of the liquidity of the metal and therefore the modulation of the pouring operation.
10029]. By measuring a high number of cycles, it is also possible to monitor the increase in the crust which forms on the bottom and on the walls of the ladle in order to preheat a new ladle so that it is immediately available,
thus avoiding idle time, when it is necessary to replace the ladle in use to remove the crust.
[0030]. Lastly, the sensor 19 also enables the measurement of the level of the liquid metal bath thanks to the hydrostatic thrust that acts on the ladle when it is dipped into the metal to collect it.
[0031]. In another version of the invented supporting device, the fairing 17 is suitable for rotating in relation to the fixed part 12 of the robot (figures 6-9).
[0032]. In particular, the fairing 17 is associated with the fixed part 12 of the robot by a bearing 25 which enables rotation between said fixed part and said fairing.
[0033]. In the abovementioned version, the sensor 19 is connected to the fairing 17 so that is fixed to said fairing.
[0034]. In yet another version, said device comprises a counterweight 27 for association with said fairing 17.
[0035]. This counterweight 27 should preferably comprise a weight 29, such as a metal, rubber or plastic block, and side elements 31a, 31b.
[0036]. In a variant, said side elements 31a, 31b have ends protruding from said weight 29 towards the shaft 15 of the device and surrounding said shaft.
[0037]. While the device is operating, the robot is
controlled in such a way as to bring the ladle into proximity with the shell in which to pour the molten metal.
[0038]. The shaft 15 of the device is rotated by the robot's drive elements and then proceeds to pour the molten metal.
[0039]. While the shaft 15 is rotating, the sensor 19 is stationary, meaning that it does not rotate together with said shaft due to the bearing 21 and the connection to the fairing 17.
[0040]. The weight of the molten metal flexes the shaft 15, as necessary during the metal pouring operation.
[0041]. In line with the stretch of the shaft 15 in which said shaft is associated with the sensor 19 by way of the bearing 21, the flexing of the shaft 15 creates a vertical movement, detected by the torque meters 23, positioned between the central element 20, which follows the stretch of the shaft 15 in its vertical movement, and the side elements 22 of the sensor 19, fastened to the fairing 17.
[0042]. In another operating condition, the ladle 11 is moved by the robot towards the shell after said robot, thanks to the immense freedom it enjoys, has performed movements that take the fixed part 12 of the robot into a position which is not horizontal with the reference
plane.
[0043]. In the variant equipped with a fairing 17 for rotation in relation to the fixed part 12 of the robot, the sensor moves, for any position assumed by said fixed part of the robot, into a position in which it can measure the vertical movement of the stretch of shaft 15 to which said sensor is associated.
[0044]. In other words, the device is equipped with means of positioning the sensor 19 in such a way as to measure the entire vertical movement of said stretch of the shaft 15, this being the movement in accordance with the direction of gravity.
[0045]. In particular, the fairing 17, due to the bearing 25 that associates it with the fixed part 12, is suitable for rotation in relation to said fixed part 12, forced, preferably, by the counterweight 27.
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