WO2024252976A1 - Lower nozzle attachment/detachment device - Google Patents

Abstract

Provided is a lower nozzle attachment/detachment device capable of reliably attaching and detaching a lower nozzle. The present invention provides a lower nozzle attachment/detachment device A for attaching and detaching a lower nozzle 72 made of refractory to or from a lower plate which is made of refractory and which is attached to a sliding nozzle device 7, the lower nozzle attachment/detachment device A including: a holding tool 1 that can be attached to and removed from a holding metal frame for holding the lower nozzle 72; a robot arm 2 having the holding tool 1 at a tip end thereof; a force sensor 3 for detecting a reaction force in a front-back direction and a reaction force in a rotation direction received by the holding tool 1 from the holding metal frame in conjunction with the operation of the robot arm 2; and a control unit 21 for monitoring and controlling the operation of the robot arm 2. The control unit 21 executes attachment/detachment of the lower nozzle 72 by controlling the operation of the robot arm 2 while monitoring each reaction force detected by the force sensor 3, and operating amounts of the robot arm in the front-back direction and the rotation direction.

Description

Lower nozzle attachment/detachment device

The present invention relates to a lower nozzle attachment/detachment device for attaching/detaching a lower nozzle used in a sliding nozzle device that controls the flow rate of molten steel during continuous casting of molten steel.

In sliding nozzle devices used in continuous casting of molten steel, a refractory nozzle, i.e., the lower nozzle, is usually placed on the underside 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 sooner than the plate lifespan expires due to damage caused by splash adhesion and oxygen cleaning. For this reason, the lower nozzle is usually held by a bayonet mechanism via an annular retaining frame that holds the lower nozzle, against a cylindrical sleeve metal fitting fixed to the underside of the plate storage frame that houses the lower plate, so that it can be replaced separately.

As an example of a device for attaching and detaching such a lower nozzle and its retaining metal frame, Patent Document 1 discloses an attachment/detachment device that includes a drive mechanism that can control the torque and rotation angle. Patent Document 2 also discloses a method for rotating the retaining metal frame of the lower nozzle with a specified torque.

Japanese Patent Application Publication No. 6-254670 Special table 2016-525452 publication

After the inventors conducted multiple tests to attach and detach the lower nozzle, they found that it is not possible to reliably attach and detach the lower nozzle by simply controlling the torque and rotation angle as in conventional technology. In other words, the lower nozzle is significantly damaged and its shape changes before and after use, and the metal retaining frame and sleeve metal of the lower nozzle also undergo significant thermal expansion due to temperature changes and deformation due to external forces, resulting in significant changes in frictional resistance when attaching and detaching. For this reason, it is not possible to reliably attach and detach the lower nozzle by simply controlling the torque and rotation angle.

The problem that this invention aims to solve is to provide a lower nozzle attachment/detachment device that can reliably attach and detach the lower nozzle.

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

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.

The present invention allows the lower nozzle to be attached and detached reliably.

FIG. 1 is an overall configuration diagram of a lower nozzle attachment/detachment device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a main portion showing a state in which the lower nozzle attachment/detachment device of FIG. 1 is used. 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 . 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 ; FIG. 2 is a perspective view showing a holder in the lower nozzle attachment/detachment device of FIG. 1 alone. 4 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 ; FIG. 6B is a longitudinal cross-sectional view of FIG. 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. FIG. 7B is a longitudinal cross-sectional view of FIG. 7B is a perspective view of the main part showing the state in which the holder is moved rearward from the state in FIG. 7A to remove the retaining metal frame that holds the lower nozzle from the sleeve metal. FIG. 8B is a longitudinal cross-sectional view of FIG. 8A. 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. FIG. 9B is a longitudinal cross-sectional view of FIG. 9A. 2 is a perspective view of a main part showing a state in which a holding metal frame holding a lower nozzle is attached to a holder in an installation operation of the lower nozzle by the lower nozzle installation/removal device of FIG. 1 ; FIG. 10B is a longitudinal cross-sectional view of FIG. 10B is a perspective view of the main part showing the state in which the holder has been 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. FIG. 11B is a longitudinal cross-sectional view of FIG. 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 shown in FIG. 11A . FIG. 12B is a longitudinal cross-sectional view of FIG. 12A.

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 receiver 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 approximately vertical.
The lower nozzle attachment/detachment device A is a device for attaching and detaching a lower nozzle 72 made of refractory material to a lower plate 71 (see FIG. 2) made of refractory material 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 to a cylindrical sleeve metal 74 fixed to the lower surface side of a plate storage metal frame 73 that stores the lower plate 71.

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 the 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 operation 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 changed.

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 (front-rear reaction forces and rotational reaction forces) detected by the force sensor 3 are always input to the control unit 21. The control unit 21 performs 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 amount of movement of the robot arm 2 in the front-rear direction and the amount of movement in the rotational direction, which will be described in detail later. Note that the amount of movement of the robot arm 2 in the front-rear direction and the amount of movement in the rotational direction are recognized by the robot arm 2 itself. That is, the robot arm 2 has a motor with an encoder for moving in the front-rear direction and the rotational direction, and the control unit 21 recognizes the amount of movement in the front-rear direction and the rotational direction based on the encoder value.

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 FIGS. 3 to 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. 2 , is inserted into the nozzle hole 721 of the lower nozzle 72 to hold the lower nozzle 72 .
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.

The holding metal frame 75, which is attached to and detached from the holder 1, has, at its lower end side, two engagement grooves 751 that engage with the locking pin 13 and two engagement holes 752 into which the locking pin 13 is inserted and engaged. Although details will be described later, the engagement groove 751 engages with the locking pin 13 when the lower nozzle 72 is removed, and the engagement 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 engagement groove 751 so as not to interfere with the locking pin 13 due to the variation in the position of the locking pin 13 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 engagement hole 752 so that the worker can finely adjust the position of the holding metal frame 75. Note that FIG. 2 shows the state at the time of attachment, that is, the state in which the engagement 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 locations on its outer circumferential surface, and the sleeve metal 74 has spiral grooves 741 at three locations into which the protrusions 753 are fitted.

Next, there will be described an operation of the lower nozzle attaching/detaching device A. First, a detaching operation for detaching the lower nozzle will be described.
First, a laser is emitted from the laser irradiator of the stereo sensor 23 toward a marker (not shown) that is a photographing 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.

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 that 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 has been omitted from Figures 6A and 6B. This also applies to the subsequent figures.

6A and 6B, the control unit 21 rotates the holder 1 in a direction in which the bayonet mechanism is loosened (counterclockwise in this embodiment) by controlling the operation of the robot arm 2, and moves the holder 1 in a 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 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 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. Figures 7A and 7B show this state in an oblique 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 shown in FIG. 6A and FIG. 6B to the state shown in FIG. 7A and FIG. 7B is approximately 3 mm and 25 degrees, respectively.

Then, 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. Next, the control unit 21 separates the seal joint between the lower nozzle 72 and the lower plate 71 by moving the robot arm 2, for example, in the vertical direction, as necessary. Then, the control unit 21 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. Furthermore, the control unit 21 controls the operation of the robot arm 2 to tilt the holder 1 downward. This allows only the lower nozzle 72 to fall 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 fall reliably when the holder 1 is tilted downward without the holding frame 75 falling.

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. In other words, the fact that at least one of the reaction forces detected by the force sensor 3 reaches a predetermined set value means that the bayonet mechanism is difficult to loosen due to an increase in friction resistance in the bayonet mechanism, etc., and if the removal operation is continued in this state, there is a risk of damage to the holder 1, 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.

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. Figures 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.

Next, just as in the removal operation described above, 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.

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 that position, and then move it further forward toward the sleeve metal 74. As a result, the upper end surface (seal joint material) of the lower nozzle 72 comes into contact with 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 an oblique view and a vertical cross section.

From this state, the control unit 21 rotates the holder 1 in the direction in which the bayonet mechanism described above tightens (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, i.e., forward. 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 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 predetermined timings and the forward movement amount and 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 completed normally. Figures 12A and 12B show this state in a perspective view and a vertical cross section.

Then, the control unit 21 controls the operation of the robot arm 2 to move the holder 1 backward. As a result, the locking pin 13 of the holder 1 disengages from the engagement hole 752 of the holding metal frame 75, and only the holder 1 moves backward.

On the other hand, when at least one of the 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 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 reaction forces detected by the force sensor 3 reaches a predetermined set value and at least one of the forward movement amount and the rotational movement amount of the robot arm does not reach 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.

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 of the robot arm 2 in the forward and backward directions and the rotational direction. This allows the lower nozzle 72 to be attached and detached reliably.

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 unit 22 Stand 23 Three-dimensional sensor 3 Force sensor 4 Ladle 41 Bottom of ladle 5 Floor 6 Ladle receiving part 7 Sliding nozzle device 71 Lower plate 72 Lower nozzle 721 Nozzle hole 73 Plate storage metal frame 74 Sleeve metal 741 Groove 75 Holding metal frame 751 Engagement groove 752 Engagement hole 753 Protrusion

Claims (5)

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. The lower nozzle attachment/detachment device according to claim 1, wherein the control unit determines that removal of the lower nozzle has been completed normally if the reaction forces detected by the force sensors during removal of the lower nozzle do not reach their respective predetermined set values and the backward movement amount and the rotational movement amount of the robot arm reach their respective predetermined set values. The lower nozzle attachment/detachment device according to claim 2, wherein the control unit determines that an abnormality has occurred in the removal process and stops the operation of the robot arm when at least one of the reaction forces detected by the force sensor reaches a predetermined set value during removal of the lower nozzle. The lower nozzle attachment/detachment device according to claim 1, wherein the control unit determines that removal of the lower nozzle has been completed normally when the reaction forces detected by the force sensors during attachment of the lower nozzle reach their respective predetermined set values, and the forward movement amount and rotational movement amount of the robot arm reach their respective predetermined set values. The lower nozzle attachment/detachment device according to claim 4, wherein 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 when at least one of the reaction forces detected by the force sensor during attachment of the lower nozzle reaches a predetermined set value, the control unit determines that an attachment abnormality has occurred and stops the operation of the robot arm.

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