Lower-nozzle attaching / detaching device

Abstract

To provide a lower-nozzle attaching / detaching device capable of positively attaching / detaching a lower nozzle.SOLUTION: A lower-nozzle attaching / detaching device A for attaching / detaching a lower nozzle 72 made of refractory to / from a lower plate made of refractory attached on a sliding nozzle device 7, comprises: a holding tool 1 that can be attached to / detached from a holding metal frame for holding the lower nozzle 72; a robot arm 2 that has the holding tool 1 at a tip; a force sensor 3 that detects reaction forces in longitudinal and rotational directions that the holding tool 1 receives from the holding metal frame due to movements of the robot arm 2; and a control unit 21 that monitors and controls the movement of the robot arm 2. The control unit 21 controls the movement of the robot arm 2 while monitoring each reaction force detected by the force sensor 3 and amounts of movements in longitudinal and rotational directions of the robot arm 2, thereby executing attaching / detaching the lower nozzle 72.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bottom nozzle attaching / detaching device for attaching / detaching a bottom nozzle used in a sliding nozzle device that controls the flow rate of molten steel in continuous casting of molten steel. [Background technology]

[0002] In a sliding nozzle device used in continuous casting of molten steel, a refractory nozzle, i.e., a lower nozzle, is usually placed on the lower surface of the plate brick, i.e., the lower plate, which controls the flow rate of molten steel, to straighten the flow of molten steel. This lower nozzle needs to be replaced earlier than the plate life span due to damage caused by adhesion of flying splashes and oxygen cleaning. Therefore, the lower nozzle is usually held by a bayonet mechanism via an annular holding frame that holds the lower nozzle, to a cylindrical sleeve metal that is fixed to the lower surface of the plate housing metal frame that houses the lower plate, so that it can be replaced separately.

[0003] As a device for attaching and detaching such a lower nozzle and its retaining metal frame, for example, Patent Document 1 discloses an attachment / detachment device including a drive mechanism capable of controlling torque and rotation angle. Patent Document 2 discloses a method for rotating the retaining metal frame of the lower nozzle with a specified torque. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-254670 [Patent Document 2] Special Publication No. 2016-525452 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors conducted repeated tests to attach and detach the lower nozzle and found that the lower nozzle cannot be attached and detached reliably by simply controlling the torque and rotation angle as in the conventional technology. In other words, the lower nozzle is significantly damaged and its shape changes before and after use, and the lower nozzle's retaining metal frame and sleeve metal are also significantly deformed by thermal expansion due to temperature changes and external forces, so the frictional resistance during attachment and detachment changes significantly. Therefore, the lower nozzle cannot be attached and detached reliably by simply controlling the torque and rotation angle.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a lower nozzle attachment / detachment device that can reliably attach and detach the lower nozzle. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors conducted further tests for attaching and detaching the lower nozzle, and found that it is effective to control the movement of the robot arm when attaching and detaching the lower nozzle by monitoring the reaction forces in the forward / backward and rotational directions acting on the robot arm, as well as the amount of movement of the robot arm in the forward / backward and rotational directions.

[0008] That is, according to one aspect of the present invention, there is provided the following lower nozzle attachment / detachment device. A lower nozzle attachment / detachment device for attaching and detaching a refractory lower nozzle to and from a refractory lower plate attached to a sliding nozzle device, the robot arm includes a holder that is detachable from a holding frame that holds the lower nozzle, a robot arm having the holder at its tip, a force sensor that detects a reaction force in a front-rear direction and a reaction force in a rotational direction that the holder receives from the holding frame as the robot arm moves, and a control unit that monitors and controls the movement of the robot arm, The control unit controls the movement of the robot arm while monitoring the reaction forces detected by the force sensors, as well as the forward / backward movement and rotational movement of the robot arm, thereby performing attachment and detachment of the lower nozzle. Effect of the Invention

[0009] According to the present invention, the lower nozzle can be reliably attached and detached. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an overall configuration diagram of a lower nozzle attachment / detachment device according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of a main part showing a state in which the lower nozzle attachment / detachment device of FIG. 1 is used. [Diagram 3] 2 is an exploded side view showing a holder and a lower nozzle to be attached and detached in the lower nozzle attachment / detachment device of FIG. 1. [Figure 4] 2 is an exploded perspective view showing a holder and a lower nozzle to be attached and detached in the lower nozzle attachment / detachment device of FIG. 1; [Diagram 5] 2 is a perspective view showing a holder in the lower nozzle attachment / detachment device of FIG. 1 alone. FIG. [Figure 6A] 3 is a perspective view of a main part showing a state in which a holder is engaged with a holding metal frame in a lower nozzle removal operation by the lower nozzle installation / removal device of FIG. 1. [Figure 6B] Longitudinal cross-section of FIG. 6A. [Figure 7A] 6B is a perspective view of the main part showing a state in which the holder is rotated counterclockwise and moved rearward from the state in FIG. 6A to remove the lower nozzle. FIG. [Figure 7B] A longitudinal section of FIG. 7A. [Figure 8A] 7B is a perspective view of the main part showing a state in which the holder is moved rearward from the state in FIG. 7A to remove the holding metal frame that holds the lower nozzle from the sleeve metal. [Figure 8B] A longitudinal section of FIG. [Figure 9A] 8B is a perspective view of the main part showing the state in which the holder has been moved rearward from the state shown in FIG. 8A to remove the lower nozzle from the sleeve metal fitting. [Figure 9B] A longitudinal cross-sectional view of FIG. 9A. [Figure 10A] 2 is a perspective view of a main part showing a state in which a holding metal frame that holds a lower nozzle is attached to a holder in the installation operation of the lower nozzle by the lower nozzle installation / removal device of FIG. 1; FIG. [Figure 10B] A longitudinal section of FIG. 10A. [Figure 11A] 10B is a perspective view of the main part showing a state in which the holder is moved forward from the state in FIG. 10A so that the protrusion of the holding metal frame is fitted into the groove of the sleeve metal. [Figure 11B] A longitudinal section of FIG. 11A. [Figure 12A] 11B is a perspective view of the main part showing a state in which the lower nozzle is attached to the lower plate by moving the holder forward while rotating it clockwise from the state in FIG. 11A. [Figure 12B] A longitudinal cross-sectional view of FIG. 12A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Fig. 1 shows the overall configuration of a lower nozzle attachment / detachment device A according to one embodiment of the present invention, and Fig. 2 shows a cross section of a main part of the lower nozzle attachment / detachment device A in use. In Fig. 1, immediately after casting, a ladle 4 is laid on its side on a ladle holder 6 placed on a floor 5. A sliding nozzle device 7 is attached to the bottom 41 of this ladle, and in the state shown in Fig. 1, the sliding direction is nearly vertical. The lower nozzle attachment / detachment device A is a device for attaching and detaching a lower nozzle 72 made of a refractory material to a lower plate 71 (see FIG. 2) made of a refractory material that is attached to the sliding nozzle device 7. As shown in FIG. 2, the lower nozzle 72 is held by a bayonet mechanism via a circular holding frame 75 that holds the lower nozzle 72, relative to a cylindrical sleeve metal 74 fixed to the underside of a plate storage metal frame 73 that stores the lower plate 71.

[0012] The lower nozzle attachment / detachment device A includes a holder 1 that can be attached and detached to a circular ring-shaped holding frame 75 that holds the lower nozzle 72, a robot arm 2 having this holder 1 at its tip, a force sensor 3 that detects the forward / backward reaction force and rotational reaction force that the holder 1 receives from the holding frame 75 as the robot arm 2 moves, and a control unit 21 that monitors and controls the movement of the robot arm 2. As shown in FIG. 1, in this embodiment, the base end of the robot arm 2 is fixed to a robot arm stand 22 installed on a floor 5. A force sensor 3 is attached to the tip of the robot arm 2. At this time, the force sensor 3 and the tip of the robot arm 2 are arranged in series so that their central axes coincide. The force sensor 3 can also be provided on the holder 1 side independently of the robot arm 2. In this case, the force sensor 3 and the tip of the robot arm 2 are also arranged in series so that their central axes coincide. The force sensor that detects the reaction force in this way is also called a force sensor, and a sensor that is generally used in robot arms and the like can be used. In this embodiment, a six-axis force sensor is used as the force sensor 3. The robot arm 2 is a six-axis vertical articulated robot arm, and the attitude and position of the holder 1 attached to the tip of the robot arm 2 can be freely moved.

[0013] In this embodiment, a stereo sensor 23 having a camera and a laser irradiator is attached to the tip of the robot arm 2. The image captured by the camera is input to an image processing device, and the three-dimensional position coordinates are corrected by an image processing method. By inputting this coordinate information to the control unit 21, the robot arm 2 can move the holder 1 to a predetermined position for attaching and detaching the lower nozzle 72. Meanwhile, the above-mentioned reaction forces (reaction forces in the forward and backward directions and reaction forces in the rotation direction) detected by the force sensor 3 are always input to the control unit 21. Then, as will be described in detail later, the control unit 21 executes the attachment and detachment of the lower nozzle 72 by controlling the operation of the robot arm 2 while monitoring the above-mentioned reaction forces detected by the force sensor 3, as well as the movement amount in the forward and backward directions and the movement amount in the rotation direction of the robot arm 2. Note that the movement amount in the forward and backward directions and the movement amount in the rotation direction of the robot arm 2 are recognized by the robot arm 2 itself. That is, the robot arm 2 has a motor with an encoder for performing movement in the forward and backward directions and the rotation direction, and the control unit 21 recognizes the movement amount in the forward and backward directions and the movement amount in the rotation direction based on the encoder value.

[0014] Next, the configuration of the holder 1 will be described. Figures 3 and 4 show an exploded view of the holder 1 and the lower nozzle 72, which is attached and detached by the lower nozzle attachment / detachment device A including the holder 1. Figure 5 shows a perspective view of the holder 1 alone. Note that the plate storage metal frame is omitted in Figures 3 and 4. As shown in FIG. 2 and FIG. 3 to FIG. 5, the holder 1 has a base body 11, and a core rod 12, a locking pin 13, and a clamp 14 attached to the base body 11. The base 11 is an annular structure having a space 111 into which the lower end of the lower nozzle 72 can be inserted, and its base end is attached to the tip of the robot arm 2. The core rod 12 is provided along the central axis of the space 111, and during use, for example, as shown in FIG. The locking pins 13 are provided at two locations so as to protrude further from the tip of the base body 11, and the clamp 14 is provided in the vicinity of one of the locking pins 13. The functions of the locking pins 13 and the clamp 14 will be described later.

[0015] The holding frame 75, which is attached to and detached from the holder 1, has, at its lower end, two engaging grooves 751 that engage with the locking pin 13 and two engaging holes 752 into which the locking pin 13 is inserted and engaged. The details will be described later, but the engaging groove 751 engages with the locking pin 13 when the lower nozzle 72 is removed, and the engaging hole 752 engages with the locking pin 13 when the lower nozzle 72 is attached. That is, when the lower nozzle 72 is removed, the locking pin 13 is engaged with the groove-shaped engaging groove 751 so as not to interfere with the locking pin 13, since the position of the locking pin 13 varies in the rotational direction. On the other hand, when the lower nozzle 72 is attached, the locking pin 13 is engaged with the hole-shaped engaging hole 752 so that the worker can finely adjust the position of the holding frame 75. Note that FIG. 2 shows the state at the time of attachment, that is, the state in which the engaging hole 752 is engaged with the locking pin 13. The retaining metal frame 75 is attached to and detached from the sleeve metal 74 by a bayonet mechanism while holding the lower nozzle 72. Specifically, as the bayonet mechanism, the retaining metal frame 75 has protrusions 753 at three points on its outer circumferential surface, and the sleeve metal 74 has spiral grooves 741 at three points into which the protrusions 753 are fitted.

[0016] Next, we will explain the operation of the lower nozzle attachment / detachment device A. First, we will explain the removal operation when removing the lower nozzle. First, a laser is emitted from the laser irradiator of the stereo sensor 23 toward a marker (not shown) that is a shooting reference portion provided on the sliding nozzle device 7, and the image is photographed by a camera and processed to calculate the deviation from the reference position of the sliding nozzle device 7 and correct the three-dimensional position coordinates of the sliding nozzle device 7. By inputting this corrected position of the sliding nozzle device 7 to the control unit 21, the robot arm 2 operates and the holder 1 attached to the robot arm 2 moves to a predetermined position in front of the lower nozzle 72 attached to the sliding nozzle device 7. Note that FIG. 1 shows a state in the middle of moving to this predetermined position.

[0017] In this embodiment, the control unit 21 controls the operation of the robot arm 2 to move the holder 1 to the above-mentioned predetermined position, stop it at the predetermined position, and then move it further forward toward the lower nozzle 72. As a result, the above-mentioned two locking pins 13 engage with the two engagement grooves 751, respectively, and the core rod 12 is inserted into the nozzle hole 721. Figures 6A and 6B show this state in a perspective view and a vertical cross section. Note that the plate storage metal frame is omitted in Figures 6A and 6B. The same applies to the subsequent figures.

[0018] From the state of FIG. 6A and FIG. 6B, the control unit 21 rotates the holder 1 in the direction in which the above-mentioned bayonet mechanism is loosened (counterclockwise in this embodiment) by controlling the operation of the robot arm 2, and moves the holder 1 in the direction in which the lower nozzle 72 is removed, that is, in the rearward direction. At this time, the control unit 21 controls the operation of the robot arm 2 while monitoring the above-mentioned reaction forces detected by the force sensor 3, as well as the rearward movement amount and the rotational movement amount of the robot arm 2. Specifically, in this embodiment, if the above-mentioned reaction forces detected by the force sensor 3 do not reach their respective predetermined set values, and the rearward movement amount and the rotational movement amount of the robot arm 2 reach their respective predetermined set values ​​at a predetermined timing, it is determined that the removal of the lower nozzle 72 has been completed normally. FIG. 7A and FIG. 7B show this state in a perspective view and a vertical cross section. That is, in this state, the bayonet mechanism is normally released, and it can be determined that the removal of the lower nozzle 72 has been completed at this stage. In this embodiment, the amount of movement of the robot arm 2 in the backward and rotational directions from the state of FIGS. 6A and 6B to the state of FIGS. 7A and 7B is approximately 3 mm and approximately 25 degrees, respectively.

[0019] Thereafter, the control unit 21 controls the operation of the robot arm 2 to move the holder 1 further backward, and removes the holding frame 75 holding the lower nozzle 72 from the sleeve metal 74 as shown in Figs. 8A and 8B. The control unit 21 then controls the operation of the robot arm 2 to separate the seal joint between the lower nozzle 72 and the lower plate 71, for example, by operating the robot arm 2 in the vertical direction as necessary. The control unit 21 then controls the operation of the robot arm 2 to move the holder 1 further backward. This allows the lower nozzle 72 to be removed from the sleeve metal 74 as shown in Figs. 9A and 9B. The control unit 21 further controls the operation of the robot arm 2 to tilt the holder 1 downward. This allows only the lower nozzle 72 to drop and be discarded. When tilting the holder 1 downward, the clamp 14 described above can be operated to reliably engage the locking pin 13 with the engagement groove 751. This allows only the lower nozzle 72 to drop reliably when the holder 1 is tilted downward without the holding frame 75 falling.

[0020] On the other hand, when at least one of the above-mentioned reaction forces detected by the force sensor 3 reaches a predetermined set value at a predetermined timing during removal of the lower nozzle 72, the control unit 21 judges that there is a removal abnormality and stops the operation of the robot arm 2. That is, when at least one of the reaction forces detected by the force sensor 3 reaches a predetermined set value, it means that the bayonet mechanism is difficult to loosen due to an increase in friction resistance in the above-mentioned bayonet mechanism, and if the removal operation is continued in this state, there is a risk of causing damage to the holder 1, the robot arm 2, etc. Therefore, in this embodiment, when at least one of the reaction forces detected by the force sensor 3 reaches a predetermined set value, the control unit 21 judges that there is a removal abnormality and stops the operation of the robot arm 2. Note that, after stopping the operation of the robot arm 2, the control unit 21 can once operate the robot arm 2 in the opposite direction and then resume the above-mentioned removal operation.

[0021] Next, the mounting operation for mounting the lower nozzle will be described. First, the holding metal frame 75 holding the lower nozzle 72 is attached to the holder 1 attached to the tip of the robot arm 2. Specifically, in this embodiment, the holding metal frame 75 holding the lower nozzle 72 is attached to the holder 1 by inserting the locking pin 13 of the holder 1 into the engagement hole 752 of the holding metal frame 75. FIGS. 10A and 10B show this state in a perspective view and a vertical cross section. Note that the above-mentioned work of attaching the holding metal frame 75 holding the lower nozzle 72 to the holder 1 can be performed by an operator. At this time, a seal joint material can be applied or installed on the upper end surface of the lower nozzle 72.

[0022] Next, similarly to the above-mentioned removal operation, a laser is emitted from the laser irradiator of the stereo sensor 23 toward a marker (not shown) that is a shooting reference portion provided on the sliding nozzle device 7, and the image is photographed by a camera and processed to calculate the deviation from the reference position of the sliding nozzle device 7 and correct the three-dimensional position coordinates of the sliding nozzle device 7. By inputting this corrected position of the sliding nozzle device 7 to the control unit 21, the robot arm 2 operates and the holding metal frame 75 and lower nozzle attached to the holder 1 move to a predetermined position just before the sleeve metal 74 fixed to the sliding nozzle device 7.

[0023] In this embodiment, the control unit 21 controls the operation of the robot arm 2 to move the holder 1 to the above-mentioned predetermined position, and after stopping it once at that predetermined position, moves it further forward toward the sleeve metal 74. As a result, the upper end surface (seal joint material) of the lower nozzle 72 contacts the lower plate 71 and the protrusion 753 of the holding metal frame 75 fits into the groove 741 of the sleeve metal 74, resulting in a position where the bayonet mechanism can be configured. Figures 11A and 11B show this state in a perspective view and a vertical cross section.

[0024] From this state, the control unit 21 rotates the holder 1 in the direction in which the bayonet mechanism is tightened (clockwise in this embodiment) by controlling the operation of the robot arm 2, and moves the holder 1 in the direction in which the lower nozzle 72 is attached, that is, in the forward direction. At this time, the control unit 21 controls the operation of the robot arm 2 while monitoring the above-mentioned reaction forces detected by the force sensor 3, as well as the forward movement amount and the rotational movement amount of the robot arm 2. Specifically, in this embodiment, when the above-mentioned reaction forces detected by the force sensor 3 reach their respective predetermined set values ​​at a predetermined timing and the forward movement amount and the rotational movement amount of the robot arm 2 reach their respective predetermined set values, it is determined that the attachment of the lower nozzle 72 has been normally completed. Figures 12A and 12B show this state in a perspective view and a vertical section.

[0025] Thereafter, the control unit 21 moves the holder 1 backward by controlling the operation of the robot arm 2. As a result, the locking pin 13 of the holder 1 is disengaged from the engagement hole 752 of the holding metal frame 75, and only the holder 1 moves backward.

[0026] On the other hand, when at least one of the above-mentioned reaction forces detected by the force sensor 3 reaches a predetermined set value at a predetermined timing during the installation of the lower nozzle 72, if at least one of the forward movement amount and the rotational movement amount of the robot arm does not reach a predetermined set value, the control unit 21 judges that the installation is abnormal and stops the operation of the robot arm 2. In other words, in this case, the bayonet mechanism is difficult to tighten due to an increase in friction resistance in the bayonet mechanism, and if the installation operation is continued as it is, there is a risk of causing damage to the holder 1, the robot arm 2, etc. Therefore, in this embodiment, the control unit 21 judges that the installation is abnormal and stops the operation of the robot arm 2 if at least one of the forward movement amount and the rotational movement amount of the robot arm does not reach a predetermined set value at a time when at least one of the above-mentioned reaction forces detected by the force sensor 3 reaches a predetermined set value. Note that, after stopping the operation of the robot arm 2, the control unit 21 can once operate the robot arm 2 in the reverse direction and then resume the above-mentioned installation operation.

[0027] As described above, in this embodiment, the control unit 21 performs attachment and detachment of the lower nozzle by controlling the operation of the robot arm 2 while monitoring the above-mentioned reaction forces detected by the force sensor 3, as well as the amount of movement in the forward and backward directions and the amount of movement in the rotational direction of the robot arm 2. This allows the lower nozzle 72 to be attached and detached reliably. [Explanation of symbols]

[0028] A Lower nozzle attachment / detachment device 1 Holder 11 Base 111 Space 12 core rod 13 Locking pin 14 Clamp 2. Robot Arm 21 Control section 22 Mounting stand 23 3D Sensor 3 Force Sensor 4 Ladle 41 Bottom of ladle 5 Beds 6 Ladle holder 7. Sliding nozzle device 71 Lower Plate 72 Bottom Nozzle 721 Nozzle hole 73 Plate storage frame 74 Sleeve hardware 741 Groove 75 Holding money frame 751 Engagement groove 752 Engagement hole 753 Protrusion

Claims

1. A lower nozzle attachment / detachment device for attaching and detaching a refractory lower nozzle to and from a refractory lower plate attached to a sliding nozzle device, the robot arm includes a holder that is detachable from a holding frame that holds the lower nozzle, a robot arm having the holder at its tip, a force sensor that detects a reaction force in a front-rear direction and a reaction force in a rotational direction that the holder receives from the holding frame as the robot arm moves, and a control unit that monitors and controls the movement of the robot arm, The control unit controls the movement of the robot arm while monitoring the reaction forces detected by the force sensors, as well as the forward / backward movement and rotational movement of the robot arm, thereby performing attachment and detachment of the lower nozzle.

2. The lower nozzle attachment / detachment device of claim 1, wherein the control unit determines that removal of the lower nozzle has been completed successfully when the reaction forces detected by the force sensors during removal of the lower nozzle do not reach respective predetermined set values ​​and the rearward movement amount and the rotational movement amount of the robot arm reach respective predetermined set values.

3. The lower nozzle attachment / detachment device of claim 2, wherein when at least one of the reaction forces detected by the force sensor during removal of the lower nozzle reaches a predetermined set value, the control unit determines that a removal abnormality has occurred and stops the operation of the robot arm.

4. The lower nozzle attachment / detachment device of claim 1, wherein the control unit determines that removal of the lower nozzle has been completed successfully when each reaction force detected by the force sensor during attachment of the lower nozzle reaches a respective predetermined set value, and when the forward movement amount and rotational movement amount of the robot arm reach respective predetermined set values.

5. The lower nozzle attachment / detachment device according to claim 4, wherein when at least one of the reaction forces detected by the force sensor during attachment of the lower nozzle reaches a predetermined set value, if at least one of the forward movement amount and the rotational movement amount of the robot arm does not reach a predetermined set value, the control unit determines that an attachment abnormality exists and stops the operation of the robot arm.

Images