JP2008188642A - Mold width changing actuator - Google Patents

Abstract

An object of the present invention is to accurately control the movement of a short side member in a mold without incurring complicated maintenance and troubles.
A ball screw 50 is rotated by driving a stepping motor 70 disposed in an actuator body 20, and a piston rod 30 is moved forward and backward from the tip of the actuator body 20 in accordance with the rotational displacement of the ball screw 50. In the mold width changing actuator 10 for moving the short side member SM, a rotary encoder 80 for detecting the rotational displacement of the ball screw 50 is disposed at the proximal end portion of the actuator body 20.
[Selection] Figure 1

Description

  The present invention relates to an actuator for changing the width of a mold for performing continuous casting.

  A mold for performing continuous casting (particularly, a mold for continuous casting of a steel slab) is generally composed of a pair of long side members and a pair of short side members. In this type of mold, the short side member is slidably disposed with respect to the long side member, and an actuator for changing the mold width is provided for each short side member. It is possible to change the width of the slab during casting by changing the distance between the short side members by driving.

  As the mold width changing actuator, a stepping cylinder is usually used. A stepping cylinder includes a stepping motor as a driving source, a ball screw that is rotated by the stepping motor, and a hydraulic cylinder in which a piston rod moves forward and backward in accordance with the rotational displacement of the ball screw. While the actuator body is held by a fixed body such as a frame, the tip of the piston rod is connected to the short side member of the mold.

  In the mold width changing actuator configured as described above, when a pulse signal is given from the controller, the stepping motor rotates in accordance with the pulse signal, and the ball screw is rotationally driven by this stepping motor. When the ball screw rotates, for example, the position of the spool with respect to the piston rod of the hydraulic cylinder is changed according to the rotational displacement, and the piston rod moves forward and backward with respect to the actuator body. As a result, since the short side member moves with respect to the long side member, the width of the slab passing through the mold is changed.

  In this type of mold width changing actuator, a rotation detector is provided in the stepping motor, and its operation is controlled based on the detection result of the rotation detector (see, for example, Patent Document 1).

JP 2000-50694 A

  By the way, the rotation detector described in Patent Document 1 can detect a shift (step-out) of the rotational displacement of the stepping motor with respect to the pulse signal, but does not directly monitor the forward / backward movement of the piston rod with respect to the actuator body. Absent. Therefore, in order to accurately control the position and posture of the short side member in the mold based on the detection result of the rotation detector, the actual position of the piston rod and the rotational displacement of the stepping motor are frequently adjusted. Therefore, there is a possibility that the maintenance work becomes complicated.

  In order to solve the above-described problem, for example, it is conceivable to provide a displacement sensor for detecting the displacement amount of the piston rod at the tip of the actuator body. However, the mold width changing actuator is in a state where the tip of the actuator body is exposed to high temperature and dust such as mold powder. For this reason, when a displacement sensor is disposed at the tip of the actuator body, troubles such as failure may occur frequently due to the influence of high temperature or the influence of dust.

  In view of the above circumstances, an object of the present invention is to provide a mold width changing actuator capable of accurately controlling the movement of a short side member in a mold without incurring complicated maintenance work and frequent troubles. There is to do.

  In order to achieve the above object, a mold width changing actuator according to claim 1 of the present invention is applied to a continuous casting mold composed of a pair of long side members and a pair of short side members, and the rotation of a ball screw. Rotational displacement that detects the rotational displacement of the ball screw in the mold width changing actuator that moves the short side member relative to the long side member by moving the piston rod back and forth from the tip of the actuator body according to the displacement The detecting means is arranged at the base end portion of the actuator body.

  A mold width changing actuator according to claim 2 of the present invention is the above-described mold width changing actuator according to claim 1, wherein a stepping motor is disposed at the base end portion of the actuator main body, and the base end portion of the actuator main body at the ball screw. The driven gear is fixed to an end corresponding to the rotating gear, and the ball screw is rotated by meshing the driven gear with the driving gear of the stepping motor. On the other hand, the rotational displacement detecting means is connected to the ball screw via the driven gear. Rotational displacement is detected.

  According to a third aspect of the present invention, there is provided the mold width changing actuator according to the first aspect, wherein the stepping motor and the rotational displacement detecting means are disposed on the outer surface of the proximal end portion of the actuator body. Features.

  According to the present invention, there is provided the rotational displacement detecting means for detecting the rotational displacement of the ball screw which is a reference for the forward / backward movement of the piston rod, so that the piston rod can be moved forward and backward based on the detection result of the rotational displacement detecting means. For example, the position and orientation of the short side member in the mold can be controlled more accurately. Moreover, since the rotational displacement detecting means is disposed at the base end portion of the actuator main body separated from the mold, it is possible to reduce the occurrence of trouble due to the influence of high temperature and the influence of dust such as mold powder as much as possible. .

  Exemplary embodiments of a mold width changing actuator according to the present invention will be explained below in detail with reference to the accompanying drawings.

  FIG. 1 shows an actuator for changing a mold width according to an embodiment of the present invention. As illustrated in FIGS. 2 and 3, the mold width changing actuator 10 illustrated here is applied to a mold M for continuous casting constituted by a pair of long side members LM and a pair of short side members SM. The short side member SM is moved with respect to the long side member LM of the mold M.

  As shown in FIG. 1, the mold width changing actuator 10 is a so-called direct acting type, and includes an actuator body 20 and a piston rod 30.

  The actuator body 20 is a base of the mold width changing actuator 10 and has a cylinder chamber 21 therein. The cylinder chamber 21 of the actuator main body 20 is formed in a columnar shape having a uniform circular cross section, and its base end is closed by the base end wall 22 of the actuator main body 20, and its front end is the actuator main body. 20 is opened to the outside through a rod sliding hole 23 a formed in the tip wall 23. The rod sliding hole 23 a is a circular opening formed with a diameter smaller than that of the cylinder chamber 21, and is provided at a position where the center thereof matches the axis C of the cylinder chamber 21.

  The piston rod 30 is configured by integrally forming a piston portion 31 and an operating rod portion 32. The piston portion 31 has a cylindrical shape having an outer diameter that fits into the cylinder chamber 21 of the actuator body 20, and is slidably fitted into the cylinder chamber 21, so that the rod side oil is placed in the cylinder chamber 21. A chamber 21a and a head side oil chamber 21b are defined. The actuating rod portion 32 has a cylindrical shape having an outer diameter that fits into the rod sliding hole 23a of the actuator main body 20, and the axial center C of the piston portion 31 from the end surface located at the rod-side oil chamber 21a. Are provided in a state of matching. The operating rod portion 32 is configured to have a length sufficient to protrude outside from the distal end wall 23 of the actuator body 20 even when the piston rod 30 is disposed at the position where the piston rod 30 is most retracted with respect to the actuator body 20. The tip portion is connected to the short side member SM of the mold M through a connecting pin P so as to be swingable. As shown in FIGS. 2 and 3, in the present embodiment, the mold width changing actuator 10 is connected to the upper part and the lower part of the short side member SM, respectively. The slab width changing device is configured. Each mold width changing actuator 10 is provided so that the connecting pin P extends in the horizontal direction, and can swing relatively around the axis of each connecting pin P with respect to the short side member SM. Is possible.

  Further, as shown in FIG. 1, the piston rod 30 is provided with a sleeve 33 and a screw accommodating portion 34. The sleeve 33 is a cylindrical hole having a relatively large diameter formed around the axis C of the piston rod 30 from the end surface facing the head side oil chamber 21b in the piston portion 31, and the inner end portion of the sleeve 33 is a piston rod. 30 is blocked. The sleeve 33 accommodates a spool 40 therein. The spool 40 has valve portions 42 each having a large cylindrical shape at both ends of a base portion 41 having a cylindrical shape. The spool 40 is fitted to the inner peripheral surface of the sleeve 33 while the valve portion 42 is fitted to the inner peripheral surface of the sleeve 33. It can be moved along the axis C and is arranged in a state in which the rotation around the axis is restricted with respect to the piston rod 30.

  The spool 40 is for switching the connection mode of the three ports 35a, 35b, and 35c opened in the sleeve 33 by changing the occupied position with respect to the piston rod 30. The three ports 35a, 35b, and 35c are opened at different positions along the axial center direction of the sleeve 33, and the first port 35a, the second port 35b, The third ports 35c are sequentially formed. The first port 35a is a sleeve-side open end of the first oil passage 36a that communicates with the rod-side oil chamber 21a, and the second port 35b is a second oil that communicates with the head-side oil chamber 21b. It is the sleeve side opening end of the path 36b. The third port 35 c is a sleeve-side opening end of a third oil passage 36 c that communicates with a drain chamber 37 formed on the outer peripheral surface of the piston portion 31.

  With respect to these three ports 35a, 35b, 35c, the spool 40 closes both the first port 35a and the third port 35c and opens the second port 35b by the valve portion 42 when occupied in the normal position. Maintain state. When the spool 40 is moved from the normal position to the tip end side, the first port 35a is switched to the state in which the third port 35c is closed and the second port 35b is communicated with the rod side oil chamber 21a and the head side oil. The chamber 21b communicates with each other. On the other hand, when the spool 40 is moved from the normal position to the base end side, the third port 35c is switched to the state in which the first port 35a is closed and the third port 35c communicates with the second port 35b. The chamber 37 communicates with the chamber 37. Although not explicitly shown in the drawing, the spool 40 has a female screw hole formed along the axis C at the center thereof.

  The screw accommodating portion 34 is a cylindrical hole having a relatively small diameter formed from the inner end surface of the sleeve 33 around the axis C of the piston rod 30, and the inner end is closed inside the piston rod 30. Yes. The screw accommodating portion 34 accommodates a ball screw 50 therein. The ball screw 50 is a long cylindrical member having an outer diameter that can be accommodated in the screw accommodating portion 34, has a thread groove 50 a on its outer peripheral surface, and has a driven gear 51 on its proximal end portion. is doing.

  The ball screw 50 has a tip portion housed in the screw housing portion 34, an intermediate portion screwed into a female screw hole (not shown) of the spool 40 via a screw groove 50 a, and a driven gear 51. The base end portion protrudes to the outside of the actuator main body 20 through an insertion hole 22 a formed in the base end wall 22 of the actuator main body 20. As is apparent from the figure, the ball screw 50 is allowed to rotate about its own axis C between the ball screw 50 and the proximal end opening of the sleeve 33, and the pressure from the head side oil chamber 21b to the sleeve 33 is allowed. A sleeve-side seal member 52 that prevents oil from entering is provided. Further, between the base end wall 22 of the actuator body 20 and the ball screw 50, the ball screw 50 is allowed to rotate about its own axis C, and the pressure oil in the head side oil chamber 21b passes through the insertion hole 22a. A main body side sealing member 53 is provided to prevent leakage to the outside.

  On the other hand, the mold width changing actuator 10 is provided with a stepping motor 70 and a rotary encoder (rotational displacement detecting means) 80 via a cover member 60 on the base end surface of the actuator body 20. The stepping motor 70 is rotationally displaced stepwise in response to the pulse signal when given, and meshes with the driven gear 51 of the ball screw 50 via the drive gear 71 fixed to the output shaft. ing. The rotary encoder 80 outputs a detection signal corresponding to the rotational displacement when the input gear 81 rotates, and meshes with the driven gear 51 of the ball screw 50 via the input gear 81. The cover member 60 functions as a cover surrounding the driven gear 51 of the ball screw 50, the drive gear 71 of the stepping motor 70, and the input gear 81 of the rotary encoder 80, and the stepping motor 70 and the rotary encoder 80 are connected to the actuator body 20. It functions as a bracket for holding the base end surface.

  The controller 90 shown in FIG. 1 gives a pulse signal corresponding to the target movement amount when the piston rod 30 is moved forward and backward with respect to the actuator body 20, and the actuator 90 based on the detection signal output from the rotary encoder 80. The movement amount of the piston rod 30 with respect to the main body 20 is calculated, and the pulse signal to be given next is determined so that the deviation between the calculated movement amount and the target movement amount becomes zero.

  Hereinafter, the operation of the above-described mold width changing actuator 10 will be described. In the following, as shown in FIG. 1, the hydraulic pump 100 is connected to the rod-side oil chamber 21a of the mold width changing actuator 10, and the drain chamber 37 is connected to the drain tank 101. To do.

  Now, when a pulse signal for moving the piston rod 30 forward is given from the controller 90 to the stepping motor 70, the stepping motor 70 rotates in a predetermined direction according to the pulse signal. When the stepping motor 70 rotates, the ball screw 50 rotates through the drive gear 71 and the driven gear 51, and the spool 40 moves toward the tip end side with respect to the piston rod 30 in accordance with the rotational displacement of the ball screw 50. As a result, the rod-side oil chamber 21a and the head-side oil chamber 21b communicate with each other, so that the hydraulic pressure from the hydraulic pump 100 acts on the oil chambers 21a and 21b. The piston rod 30 moves forward with respect to the main body 20. When the piston rod 30 moves forward, the spool 40 relatively moves to the base end side and returns to the normal position, so that the position is maintained. Thereafter, by continuing to output the pulse signal to the stepping motor 70, the piston rod 30 advances and moves sequentially with respect to the actuator body 20.

  On the other hand, when a pulse signal for causing the piston rod 30 to retract and move from the controller 90 is supplied to the stepping motor 70, the stepping motor 70 rotates in the opposite direction according to the pulse signal. When the stepping motor 70 rotates in the reverse direction, the ball screw 50 rotates in the reverse direction via the drive gear 71 and the driven gear 51, and the spool 40 moves relative to the piston rod 30 in accordance with the rotational displacement of the ball screw 50. Move to the base end side. As a result, the head side oil chamber 21b and the drain chamber 37 communicate with each other, so that the hydraulic pressure from the hydraulic pump 100 acts only on the rod side oil chamber 21a, and the piston rod 30 moves in a contracted manner relative to the actuator body 20. Will do. When the piston rod 30 is retracted, the spool 40 is relatively moved to the tip end side and returned to the normal position, so that the position is maintained. Thereafter, by continuing to output the pulse signal to the stepping motor 70, the piston rod 30 sequentially retracts relative to the actuator body 20.

  During these operations, a detection signal is given from the rotary encoder 80 of the mold width changing actuator 10 to the controller 90, and the amount of movement of the piston rod 30 relative to the actuator body 20 is calculated based on this detection signal. Further, the controller 90 determines a pulse signal to be given next so that the deviation between the calculated movement amount and the target movement amount becomes zero, and outputs the determined pulse signal to the stepping motor 70 of the mold width changing actuator 10. Yes.

  Here, the detection signal output from the rotary encoder 80 is not based on the rotational displacement of the stepping motor 70 itself, but based on the rotational displacement of the driven gear 51 fixed to the base end portion of the ball screw 50. That is, the rotary encoder 80 detects the rotational displacement of the ball screw 50 that is a reference for the forward and backward movement of the piston rod 30 and outputs a detection signal corresponding to the rotational displacement. Therefore, according to the mold width changing actuator 10, it is possible to more accurately control the forward / backward movement of the piston rod 30 with respect to the actuator body 20 without frequently performing adjustment work. Accordingly, as shown in FIG. 2, in the mold M, the short side member SM can be accurately moved with respect to the long side member LM. For example, the slab SG passing through the mold M during continuous casting. It becomes possible to accurately control the width of.

  Moreover, the rotary encoder 80 is disposed at the outer surface of the base end wall 22 located on the base end side of the actuator body 20 that is farthest from the mold M exposed to high temperature and dust such as mold powder. The meshing portion between the driven gear 51 of the ball screw 50 and the input gear 81 of the rotary encoder 80 is covered with the cover member 60. Therefore, the influence of high temperature and the influence of dust on the components of the rotary encoder 80 can be reduced as much as possible, and it is possible to prevent the occurrence of troubles such as failures due to these influences. Therefore, the maintenance work for dealing with these troubles will be significantly reduced.

  In the above-described embodiment, the stepping motor is applied as a driving source for driving the ball screw. However, the stepping motor is not necessarily applied, and is driven to rotate in response to a command signal. If so, other rotary drive sources may be applied.

  In the above-described embodiment, as a means for converting the rotational displacement of the ball screw into the forward / backward movement of the piston rod, the spool engaged with the ball screw is directly moved to switch the connection mode of the oil passage formed on the piston rod. However, these configurations are merely examples, and other means may be applied to convert the rotational displacement of the ball screw into the forward / backward movement of the piston rod.

1 is a sectional side view conceptually showing the structure of a mold width changing actuator according to an embodiment of the present invention. It is a conceptual diagram which shows the slab width changing apparatus of the mold for continuous casting to which the actuator for mold width change shown in FIG. 1 is applied. It is a top view of the slab width changing apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold width change actuator 20 Actuator main body 21 Cylinder chamber 22 Base end wall 23 Front end wall 30 Piston rod 31 Piston part 32 Actuation rod part 33 Sleeve 34 Screw accommodating part 40 Spool 50 Ball screw 50a Screw groove 51 Driven gear 70 Stepping motor 71 Drive Gear 80 Rotary encoder 81 Input gear 90 Controller

Claims (3)

By applying a continuous casting mold constituted by a pair of long side members and a pair of short side members, and moving the piston rod forward and backward from the tip of the actuator body according to the rotational displacement of the ball screw, the long side In the mold width changing actuator for moving the short side member relative to the member,
A mold width changing actuator characterized in that a rotational displacement detecting means for detecting a rotational displacement of the ball screw is disposed at a proximal end portion of the actuator body.   A stepping motor is disposed at the base end portion of the actuator body, and a driven gear is fixed to the end of the ball screw corresponding to the base end portion of the actuator body, and the driving gear of the stepping motor is toothed on the driven gear. 2. The mold width changing actuator according to claim 1, wherein the rotational displacement detecting means detects rotational displacement of the ball screw through the driven gear while rotating the ball screw by combining.   2. The mold width changing actuator according to claim 1, wherein the stepping motor and the rotational displacement detecting means are arranged on the outer surface of the proximal end portion of the actuator body.

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