JP6476946B2 - Electrode length measuring device - Google Patents

Description

  The present invention relates to an electrode length measuring device, and more particularly to an electrode length measuring device capable of measuring the length of an electrode used for melting a metal material in an electric furnace.

  In an electric furnace that melts the metal material accommodated in the furnace body using arc discharge, the electrode is consumed and shortened by repeated discharge, but the distance between the metal material and the electrode is adjusted. This is important in controlling the melting conditions of the metal material. For that purpose, it is required to measure the length of the electrode after continuing the discharge to some extent.

  As an electrode length measuring device, for example, one disclosed in Patent Document 1 as an electrode length adjusting device is known. In Patent Document 1, a pedestal for receiving an electrode outside the furnace is provided, and means such as an encoder for detecting the position of the gripper of the electrode lifting device, and an optical sensor for detecting that the lower end of the electrode is in contact with the cradle. And means such as a limit switch. When the electrode grasped by the gripper is lowered and the lower end contacts the cradle, this is detected and the lowering of the gripper is stopped. Then, based on the change in the count number of the encoder, which is a means for detecting the position of the gripper at this time, the electrode protrusion length below the gripper is calculated. In this type of electrode length measuring device, the cradle is usually made of a rigid body such as a refractory block, and the surface with which the lower end of the electrode contacts is formed as a flat surface (see FIG. 1 in Patent Document 1).

JP-A-9-318269

  As shown in FIG. 5A, in the electrode E before discharge, the tip E1 is usually processed so as to have a substantially symmetrical shape around the axis of the electrode E and to be flat. ing. However, when the electrode E is used for discharge, the tip E1 is not always consumed while maintaining an axisymmetric and flat shape. For example, when discharging using a plurality of electrodes, as shown in FIG. 5 (b), wear occurs quickly in a portion on the direction d1 side facing the other electrodes, while on the opposite direction d2 side. The consumption of the part is slow, and the tip E1 may have a sharp shape that is biased toward the direction d2. Alternatively, breakage may occur due to the electrode E colliding with the metal material during discharge, and in this case, the tip E1 can take a complicated shape deviating from axial symmetry.

  As described above, in Patent Document 1, the pedestal for contacting the tip of the electrode has a flat surface, and the tip E1 receives the electrode E in which the tip E1 is axisymmetric and flat as shown in FIG. When contacted with the table, a certain wide area centered on the axis of the electrode E contacts the receiving table, and the contact is easily detected with high sensitivity. However, when the tip E1 deviates from axial symmetry as shown in FIG. 5B and the electrode E having a sharp and complicated shape is brought into contact with the cradle, the position deviated from the position of the electrode axis. Since the pedestal is contacted in a narrow area, the contact of the electrode E becomes difficult to be detected. As a result, there is a possibility that the length of the electrode E cannot be measured stably. For example, as described in Patent Document 1, the means for detecting the contact of the electrode E is an optical sensor, and the contact of the electrode E is detected by detecting that the tip E1 of the electrode E blocks light. Even if the tip E1 of the electrode E contacts the cradle at the pointed portion on the direction d2 side in FIG. 5B, the detection light passes through the portion where the wear on the direction d1 side of the electrode E proceeds. It can happen that it is not blocked. Alternatively, as described in Patent Document 1, the means for detecting contact of the electrode E is a limit switch, and the limit switch is brought into contact with a cradle supported by a spring so that the electrode E contacts the cradle. When the contact is detected by lowering the cradle and energizing the limit switch when the tip E1 on the direction d2 side in FIG. 5B contacts the cradle, Therefore, there is a possibility that the cradle cannot be pushed down sufficiently. Further, because of the asymmetric shape, a downward force is applied to a position deviated from the center of the cradle toward the direction d2, so that the cradle may tilt and the limit switch may not be operated correctly.

  The problem to be solved by the present invention is to provide an electrode length measuring device capable of stably measuring the length of an electrode even when the tip of the electrode has a complicated shape.

  In order to solve the above problems, an electrode length measuring device according to the present invention includes a gripping part that grips an electrode, a lifting part that lifts and lowers the gripping part, and a gripping position detection that detects a vertical position of the gripping part. And a container that descends when a force is applied to the bottom surface from above, and a descent detector that detects descent of the container. The electrode is lowered from the reference position by the electrode contact portion in which the container is filled with a heat-resistant granular material having a melting point higher than the temperature, and the elevating portion, and the descent detecting portion detects the descent of the container And a control unit that detects the length of the electrode from the position of the gripping part to the lower end based on the amount of change in the position of the gripping part detected by the gripping position detection part. And

  Here, sand can be mentioned as the heat resistant powder. Moreover, it is preferable that the said fall detection part can be attached to the several position around the axis | shaft in which the said electrode penetrate | invades into the said container. An example of the lowering detection unit is a limit switch.

  The container integrally has a guide surface extending downward, and is supported above the installation surface via an urging means for urging the container upward. A standing wall facing the guide surface is erected, and one of the guide surface and the standing wall faces the other surface at a portion facing the other surface, so that the guide surface with respect to the standing wall It is preferable that an inclination restricting portion for restricting the inclination of the lens is provided. At this time, the inclination restricting portion is formed of a rod-shaped member fixed along the standing wall and having a circular cross-section in the vertical direction, and the diameter of the cross-section of the rod-shaped member is between the rod-shaped member and the guide surface. A narrower gap may be provided.

  The electrode length measuring apparatus as described above is an electric furnace that melts the metal material by causing a discharge through the electrode in the furnace body containing the metal material, or a furnace body containing the metal material with respect to the axis of the electrode. And can be provided together with a swivel electric furnace that melts the metal material by causing discharge through the electrodes.

  In the electrode length measuring device according to the invention, the inside of the container is filled with powder particles, and when the electrode gripped by the grip portion is lowered by the lifting and lowering portion, the tip of the electrode is granulated from the opening. It will be in contact with the body layers. Then, a downward force is applied to the granular material from the tip of the electrode, and the granular material transmits the force to the bottom surface of the container, so that the container is lowered and detected by the lowering detection unit. Since the force applied from the tip of the electrode is spatially dispersed and transmitted to the bottom surface of the container due to the presence of the powder, the container can be used even when the tip of the electrode has a shape deviating from axial symmetry. Is stably pushed down, and the lowering of the container is more easily detected as compared with the case where no powder particles are present. In addition, even when the tip of the electrode is sharp, the tip is intruded into the powder layer, so that force is transmitted from the large area of the electrode surface to the powder and the container is lowered sufficiently. It becomes easy. As a result, the length of the electrode can be stably measured even when the shape of the tip of the electrode is complicated. In addition, since the granular material has a melting point higher than the temperature of the electrode, the length can be measured even for an electrode in a state where the temperature is high after discharging or energizing. .

  Here, when the heat-resistant granular material is sand, the container can be densely packed, and even when it comes into contact with an electrode in an extremely high temperature state, it is not substantially denatured and is stable in length. The heat-resistant powder that contributes to the measurement can be used at low cost.

  In addition, when the lowering detection unit can be attached at a plurality of positions around the axis where the electrode enters the container, the tip of the electrode has a shape deviating from axial symmetry, so that However, when the container is lowered unevenly and tilted, a drop detection unit is attached at a position where it can easily be lowered, and the drop detection unit detects the drop of the container with high sensitivity. can do.

  Further, the container integrally has a guide surface extending downward, and is supported above the installation surface via an urging means for urging the container upward, and faces the guide surface to the installation surface. An upright wall is erected, and either one of the guide surface and the upright wall is provided with an inclination restricting portion that restricts the inclination of the guide surface relative to the upright wall by contacting the other surface at a portion facing the other surface. If the container is lowered due to contact and insertion of the electrode to the granular material, the container returns to the original position when the electrode is separated, and the electrode length Measurement can be repeated. In addition, when the inclination regulating member is provided between the guide surface integrated with the container and the standing wall fixed to the installation surface, the container supported by the installation surface through the biasing means is moved up and down. Even if it tries to incline, the inclination is regulated and the smooth raising and lowering of the container is assisted. Thereby, the length of the electrode can be measured more stably.

  At this time, the inclination restricting portion is made of a rod-shaped member whose vertical cross section is fixed along the standing wall, and a gap narrower than the diameter of the cross-section of the rod-shaped member is provided between the rod-shaped member and the guide surface. In such a case, even if the container is tilted, the tilting portion can be provided with a simple configuration because the guide surface and the rod-shaped member are in contact with each other so that further tilting is regulated. In addition, since the rod-shaped member has a circular cross section, even when the rod-shaped member and the guide surface come into contact with each other, the vertical movement of the container is smoothly guided. On the other hand, since the gap is provided between the guide surface and the rod-like member, a certain degree of inclination of the container is allowed. Therefore, even when the container has a slight inclination, the length of the electrode can be measured. Can continue.

It is a side view showing the outline of the electrode length measuring device concerning one embodiment of the present invention. It is a fragmentary sectional view showing the electrode contact part of the above-mentioned electrode length measuring device, (a) shows the state where the electrode is not in contact, and (b) shows the state where the electrode is in contact. It is an enlarged view which shows the area | region of the lower part of an electrode contact part. It is a top view of the form which provided three electrode contact apparatuses. It is a side view which shows the shape of the front-end | tip of an electrode, (a) is before using for discharge, (b) has shown the state after using for discharge.

  Hereinafter, an electrode length measuring device according to an embodiment of the present invention will be described with reference to the drawings.

[Outline of electrode length measuring device]
An electrode length measuring device 1 according to an embodiment of the present invention has a configuration as shown in FIG. The electrode length measuring device 1 is installed in the vicinity of an electric furnace that melts a metal material by arc discharge, for example, and is used to measure the length of an electrode used for discharge. An electrode such as a carbon electrode is used for melting a metal material, but this type of electrode is consumed and shortened by discharge. Therefore, from the viewpoint of controlling discharge conditions, the length is measured after a predetermined time of use. It is necessary to grasp the degree of wear. This electrode length measuring device 1 measures the length of this electrode. The electrode length measuring device 1 has the same configuration as the electrode length adjusting device disclosed in Patent Document 1 except for the electrode contact portion 10. The outline will be briefly described below.

  As shown in FIG. 1, the electrode length measuring device 1 drives the movement of the electrode E via the electrode contact portion 10 that detects the contact of the electrode E, the grip portion 30 that grips the electrode E, and the grip portion 30. And a control unit 40 for controlling them. In the electrode length measuring apparatus 1, a long electrode E formed in a substantially cylindrical shape and solid is gripped by the grip portion 30, and the length thereof is measured.

  The gripping part 30 is a clamp-shaped member that sandwiches and grips the electrode E having an axis arranged in the vertical direction from the outer peripheral direction. The grip part 30 can be switched between a state in which the electrode E is gripped and a state in which the grip is released by being opened and closed by a cylinder mechanism 31 controlled by the control unit 40. Even in the state where the gripping by the gripping part 30 is released, the electrode E is held in a state where it does not fall down due to the contact with the gripping part 30.

  The drive part 20 has a hydraulic cylinder, for example as the raising / lowering part 22 which drives a vertical motion. The output shaft of the hydraulic cylinder is connected to the column 21a. And the support | pillar 21b has couple | bonded between the support | pillar 21a and the holding part 30. FIG. Accordingly, when the vertical movement is driven by the elevating unit 22, the gripping unit 30 and the gripped electrode E are moved up and down. The hydraulic cylinder of the elevating unit 22 is provided with a gripping position detection unit 24 made up of a linear encoder, and plays a role of detecting the vertical position of the gripping unit 30. The linear encoder outputs the read count to the control unit 40. In addition, although the form which uses a hydraulic cylinder as the raising / lowering part 22 is shown here, as the patent document 1 shows, you may construct the raising / lowering part 22 using a moving pulley. Further, although a linear encoder is used as the gripping position detection unit 24, as shown in Patent Document 1, an array of optical sensors, limit switches, or the like may be used.

  Although the configuration of the electrode contact portion 10 will be described in detail later, the electrode contact portion 10 is disposed immediately below the grip portion 30, and when the electrode E is lowered by the elevating portion 22 and the tip (lower end) E1 contacts, the contact is detected. To send a signal to the control unit 40. The control part 40 consists of a well-known arithmetic unit.

  When measuring the length of the electrode E, the control unit 40 controls the elevating unit 22 to move the gripping unit 30 from a predetermined reference position where the tip E1 of the electrode E is sufficiently away from the electrode contact unit 10. Lower. When the tip E1 of the electrode E comes into contact with the electrode contact portion 10, a signal indicating that is input to the control portion 40, and the control portion 40 stops the lowering of the grip portion 30 by the elevating portion 22. Then, the control unit 40 calculates the amount of movement of the gripping unit 30 from the reference position based on the amount of change from the reference position in the count number output by the linear encoder of the gripping position detection unit 24. Furthermore, since the height of the upper surface of the electrode contact portion 10 and the reference position from the installation surface P on which the electrode contact portion 10 is installed is known, based on the known height and the calculated movement amount of the grip portion 30, The length of the electrode E from the position of the grip portion 30 to the tip E1 (length under the neck) is calculated.

  Since the electrode E is consumed and shortened when used for discharge, if the under-neck length measured as described above is shorter than a predetermined reference length, before the discharge is performed again, the grip portion It is desirable to move the position gripped at 30 above the electrode E to increase the length under the neck. This is because the discharge condition largely depends on the distance between the metal material in the furnace and the electrode E, and if the distance is too long, the discharge does not occur effectively. Specifically, if the length under the neck calculated by the control unit 40 is shorter than the reference length, the control unit 40 holds the electrode E while keeping the tip E1 of the electrode E in contact with the electrode contact unit 10. After the gripping part 30 is opened by the cylinder mechanism 31 connected to the part 30, the gripping part 30 is raised along the electrode E by the elevating part 22. When the elevating part 22 is raised by a desired distance, the raising is stopped and the gripping part 30 is closed by the cylinder mechanism 31. What is necessary is just to employ | adopt the method described in patent document 1 as the determination method of the raise amount of the holding part 30. FIG.

[Configuration of electrode contact area]
Next, the electrode contact portion 10 will be described in detail. The electrode contact portion 10 has a configuration as shown in FIGS. The electrode contact portion 10 includes a block-shaped refractory 12 and a metal container 14 fixed integrally above the refractory 12. The combination of the refractory 12 and the container 14 is supported above the installation surface P by a coil spring 16 as an urging means disposed with its axis directed in the vertical direction.

  The container 14 is formed in a bottomed cylindrical shape, and has an upper opening through which the tip E1 of the descending electrode E can enter. The container 14 is filled with sand 15. For example, three coil springs 16 are provided so as to stably support the container 14 filled with the refractory 12 and the sand 15 (see FIG. 4). Further, a limit switch 18 is fixed to the installation surface P as a lowering detection unit that detects the lowering of the container 14. A striker 18 a is fixed to the outside of the container 14 above the limit switch 18. A signal output from the limit switch 18 is input to the control unit 40. In the state where the external force in the vertical direction is not applied to the container 14, the limit switch 18 and the striker 18 a are separated from each other in the vertical direction, but the striker 18 a is brought into contact with the limit switch 18 by lowering the container 14 by the external force. A signal is output toward the unit 40.

  A substantially cylindrical standing wall 17 is erected on the installation surface P so as to surround an area where the coil spring 16 is installed. The container 14 is provided with a guide surface 14a with a side wall extending downward. The guide surface 14 a is formed in a substantially cylindrical shape having a larger diameter than the standing wall 17 fixed to the installation surface P, and is disposed to face the surface of the standing wall 17 so as to surround the outside of the standing wall 17. An inclination regulating portion 19 is disposed between the installation surface P and the guide surface 14a at a portion where the installation surface P and the guide surface 14a face each other. The inclination restricting portion 19 is a rod-shaped member having a substantially circular cross section and formed into a substantially annular shape. The inclination restricting portion 19 has an annular inner diameter substantially equal to the outer diameter of the standing wall 17, and is fixed to the standing wall 17 by welding in a state where the center axis of the annular ring is arranged in the vertical direction along the outer periphery of the standing wall 17. Has been. On the other hand, in a state where the container 14 is upright, the inclination regulating portion 19 and the guide surface 14a are not in contact with each other, and there is a gap G therebetween.

  As shown in FIG. 2B, when the tip E1 of the electrode E lowered by the elevating part 22 reaches the region filled with the sand 15 in the container 14, the tip E1 of the electrode E is the surface of the layer of the sand 15. To touch. Alternatively, it further intrudes into the layer of sand 15. Then, a downward force is applied to the layer of sand 15, and the force is transmitted to the bottom surface of the container 14 through the layer of sand 15, and the container 14 descends together with the refractory 12 while compressing the coil spring 16. To do. Then, the striker 18 a fixed to the container 14 contacts the limit switch 18 fixed to the installation surface P, and a signal indicating this is transmitted to the control unit 40. Thereby, the control unit 40 recognizes the descent of the container 14, that is, the contact of the electrode E with the electrode contact unit 10, and stops the descent of the electrode E by the elevating unit 22. Subsequent calculations in the control unit 40 for calculating the neck length of the electrode E are as described above. Since the container 14 is urged upward by the coil spring 16, when the electrode E is raised again and separated from the surface of the layer of the sand 15, the compression of the coil spring 16 is released, and the original FIG. Return to the state. Thereby, it becomes possible to measure the neck length of the electrode E again.

  In many cases, a plurality of electrodes E are used simultaneously as in the case where the melting of the metal material is performed by discharging from the plurality of electrodes E. In this case, the same number of electrode contact portions 10 as the electrodes E are provided, They may be arranged according to the arrangement of the electrodes E. For example, in FIG. 4, the form corresponding to the case where three electrodes E are used is shown as a top view. The three electrode contact portions 10 are installed on a base 50 that serves as a common installation surface P.

  Although one limit switch 18 is provided for one electrode contact portion 10, it is preferable that the limit switch 18 be attachable to a plurality of positions having different angular positions around the central axis of the electrode contact portion 10. For example, in the example shown in FIG. 4, three sets of mounting holes for mounting the limit switch 18 by screw fastening are provided on the base 50 so as to surround the outer periphery of each electrode contact portion 10 and be separated by 120 °. (51a-51c). Further, three attachment pieces for attaching the striker 18a are also provided on the outer wall of the container 14 (52a to 52c). As a result, the limit switch 18 and the striker 18a can be attached by selecting one of the three attachment positions provided around the central axis of the container 14 that is the axis through which the electrode E enters.

  As described above, the electrode contact portion 10 detects the lowering of the container 14 by bringing the tip E1 of the electrode E into contact with or intruding into the layer of the sand 15 filled in the container 14 so that the electrode 14 is lowered. Even if the tip E1 of E has a complicated shape, it is possible to stably detect the descent of the container 14, that is, the contact of the electrode E with the electrode contact portion 10. As shown in FIG. 5B, the tip E1 of the electrode E used for discharge tends to take a shape greatly deviating from axial symmetry or a sharp pointed shape due to uneven wear and breakage. As described in Patent Document 1, when the tip E1 of the electrode E is brought into contact with a rigid body such as a refractory block and the lowering of the rigid body is detected by a limit switch, the downward force applied to the rigid body The situation where the rigid body tilts due to non-uniformity, and the situation where the rigid body does not descend with a sufficient amount of displacement due to the force not being applied to a sufficiently wide region can occur. In these cases, the limit switch does not operate, and the lowering of the rigid body, that is, the contact of the electrode E may not be sufficiently detected.

  On the other hand, in this electrode contact part 10, since the electrode E contacts the surface of the layer of sand 15 and a force is applied to the layer of sand 15, the force is applied to the sand 15 due to the nature of the particles as a granular material. Spatially dispersed in the 15 layers and applied to the bottom surface of the container 14 to lower the container 14. Therefore, as shown in FIG. 5 (b), the portion deviated from the center of the electrode E is pointed, and even if a non-uniform force is applied to the surface of the sand 15 layer, the sand 15 layer is not uniform. And the force is transmitted to a wide area of the bottom surface of the container 14. Thereby, the container 14 is easily lowered with a small inclination and with a large displacement. As a result, when the container 14 is lowered, that is, when the contact of the electrode E with the electrode contact portion 10 is detected, the uncertainty of detection / non-detection due to the shape of the tip E1 of the electrode E is reduced, and the contact of the electrode E is stabilized. Can be detected. Thereby, the accurate measurement of the neck length of the electrode E is possible.

  In particular, when the tip E1 of the electrode E is not only in contact with the surface of the layer of sand 15, but when it is indented into the layer of sand 15 as shown in FIG. Therefore, a force is received from a wide area on the surface of the electrode E. Thereby, the layer of sand 15 disperses the force applied from the electrode E more effectively and transmits it to the bottom surface of the container 14, so that the descent of the container 14 is detected more stably.

  Further, as described above, the electrode length measuring device 1 not only measures the neck length of the electrode E, but also changes the gripping position of the electrode E by the gripping part 30 based on the measurement result. Although functioning as an apparatus is also achieved, the presence of the sand 15 enables stable gripping. While the gripper 30 is moved in the open state for gripping, the electrode E is not fixed to the gripper 30 and is in an unstable state. However, at this time, since the tip E1 of the electrode E is in contact with the layer of sand 15, in particular, is invaginated, it is held stably, so that the state where the electrode E stands substantially vertically is easily maintained. Thereby, the movement of the holding part 30 along the electrode E can be performed smoothly.

  The substance to be filled in the container 14 is not limited to sand, but may be any granular material made of an inorganic material having a melting point higher than the temperature of the tip E1 of the electrode E during length measurement. In the case of the carbon electrode E immediately after the end of the arc discharge, the temperature of the tip E1 is about 2000 ° C. It is required that the granular material in contact with the tip E1 of the electrode E does not undergo denaturation such as melting even at this temperature. Examples of such materials include inorganic oxides, carbides, and nitrides. Sand is very stable even at high temperatures as described above, and can be filled with high density. And since it can obtain cheaply, it is especially suitable.

  Furthermore, in this electrode contact part 10, as shown in FIG. 4, the limit switch 18 which detects the fall of the container 14 can be attached to a several position. For this reason, by selecting a portion where the lowering of the container 14 is easily detected and attaching the limit switch 18, it is possible to increase the sensitivity of detection and to measure the neck length of the electrode E more stably. Specifically, when the part of the tip E1 (in the direction d2 side in FIG. 5B) protrudes from the other part due to uneven consumption of the electrode E, the protruding part Since the electrode contact portion 10 is contacted and a downward force is applied, the container 14 is inclined downward at a position corresponding to the protruding portion, and the amount of lowering tends to be large. As described above, by disposing the sand 15 at the portion that contacts the electrode E and dispersing the force applied from the electrode E to the electrode contact portion 10, the inclination when the container 14 descends can be suppressed, and the amount of descending Although such non-uniformity can be alleviated, there is a possibility that such non-uniformity cannot be completely eliminated. However, if the attachment position close to the part where the descending amount of the container 14 is close and the limit switch 18 is attached, even if there is a part where the descending amount is small in the entire container 14, the container 14 can be lowered with high sensitivity. Can be detected.

  Depending on the shape of the tip E1 of the electrode E, the positional relationship with the furnace body, the relative arrangement of the plurality of electrodes E, and the like, which part of the electrode E is easily consumed is fixed to some extent. For example, when arc discharge is performed by arranging three electrodes E so as to form the apex of a triangle, each electrode has a portion facing the other electrode E (direction d1 in FIG. 5B). ), The output of the arc is increased, and this part is easily consumed. That is, the electrode E is easily consumed at the portion facing the inside of the triangle formed by each electrode E, whereas the electrode E is not easily consumed at the portion facing the outside of the triangle, and the outside protrudes from the inside. . Therefore, as shown in FIG. 4, in the three electrode contact portions 10 arranged at the vertices of the triangle, each of the attachment positions corresponding to the outside of the triangle (in the case of the upper left electrode contact portion 10, the attachment hole 51c and the attachment If the limit switch 18 and the striker 18a are attached to the piece 52c), it is usually possible to detect the descent of the container 14 with the highest sensitivity. However, the spatial pattern of electrode E consumption during discharge can change with each measurement due to various factors such as non-uniformity of metal material in the furnace in each operation. There is sex. Further, when the electrode E is broken, the tip shape may be completely different. In such a case, the limit switch 18 may be attached by selecting an attachment position where the amount of lowering of the container 14 is relatively large.

  Furthermore, in this electrode contact part 10, it fixes to the standing wall 17 fixed to the installation surface P, and the container 14 from a viewpoint of suppressing the inclination of the container 14 resulting from the above nonuniformity of the shape of the electrode E, etc. An inclination regulating portion 19 is disposed between the guide surfaces 14a. The container 14 is supported on the installation surface P via the coil spring 16, and when a force is applied non-uniformly to the bottom surface of the container 14 due to non-uniformity of the tip shape of the electrode E, the coil 14 Although the container 14 tends to incline within a range in which the spring 16 can be bent, the inclination of the container 14 is limited within a predetermined range by the guide surface 14a coming into contact with the inclination restricting portion 19. In this way, a straight descent of the container 14 is induced. Furthermore, since the inclination restricting portion 19 has a smooth curved surface with a substantially circular cross section, the lowering of the container 14 can be smoothly guided even when the guide surface 14a is in contact.

  If tilting of the container 14 is not allowed at all, there is a possibility that the container 14 cannot be lowered to a position where the limit switch 18 can be actuated when an uneven force is applied to the bottom surface of the container 14, and the guide surface 14a There is a possibility that so-called galling may occur between the standing walls 17 and, on the contrary, measurement of a stable electrode length will be hindered. However, since the gap G is provided between the inclination restricting portion 19 and the guide surface 14a, A certain amount of inclination of the container 14 is allowed, and stable detection of the lowering of the container 14 is promoted. The width of the gap G may be selected according to the allowable degree of inclination of the container 14, but from the viewpoint of effectively restricting the inclination of the container 14, the substantially circular cross section of the bar constituting the inclination restricting portion 19. It is preferable that it is narrower than the diameter. A case where the width of the gap G is about 1/6 with respect to the diameter of the bar of the inclination restricting portion 19 can be given as a particularly preferable example. Although the inclination restricting portion 19 is fixed to the standing wall 17 here, it may be fixed to the guide surface 14 a side and a gap G may be provided between the standing wall 17.

[Combination of electrode length measuring device and electric furnace]
As described above, the electrode length measuring device 1 according to the embodiment of the present invention is provided in an electric furnace that melts a metal material by arc discharge, and performs measurement and gripping of the electrode E consumed by the discharge. It can be used suitably. Further, since the discharge condition largely depends on the distance between the metal material and the electrode E, the volume of the unmelted metal material accommodated in the furnace body decreases with the progress of melting of the metal material, and the metal material The position of the electrode E may be lowered using the elevating part 22 when the height position of the upper surface of the electrode is lowered. When the operation of melting the metal material in the electric furnace is repeated many times, the length under the neck of the electrode E is measured by using the electrode length measuring device 1 during the time between the operations. Accordingly, the electrode E may be replaced or replaced.

  In this electrode length measuring device 1, since the length measurement of the electrode E can be performed stably, the length measurement and the gripping change of the electrode E can be performed easily and in a shorter time than when the conventional electrode length measuring device is used. can do. This contributes to efficient melting of the metal material. In addition, as described above, when the control for lowering the height of the electrode E is performed during the melting process in response to the volume change accompanying the melting of the metal material, the electrode E is used in advance by using this electrode device. By measuring the length under the neck with high accuracy, the height of the electrode E can be accurately controlled and the efficiency of melting can be increased.

  Here, the electric furnace may be a swivel electric furnace having a plurality of electrodes E and capable of swiveling a furnace body containing a metal material with respect to the axes of the electrodes E. When a metal material is melted using a plurality of electrodes E, a hot spot where the metal material is easily melted is formed at a portion close to each electrode E, whereas the metal material is hardly melted at a portion between the electrodes. A cold spot is formed, and the molten state of the metal material is unevenly distributed around the axis of the electrode E (see, for example, JP-A-2014-40965). Therefore, the melting state is uneven by rotating the furnace body with respect to the axis of the electrode E in the course of melting, changing the relative positions of the electrode E and the furnace body, and changing the positions of the hot spot and the cold spot. The melting efficiency can be improved. By using both the swivel electric furnace and the electrode length measuring device 1, the entire operation process of alternately repeating the melting of the metal material and the measurement of the length under the neck of the electrode E by utilizing the efficiency provided by both of them. Can be performed with high efficiency.

  Further, when a metal material is melted using a plurality of electrodes E, due to non-uniformity in the size of the lump of metal material charged into the furnace body, around one electrode, around the other electrode The melting of the metal material may be slower than that. In such a case, it is better to reliably melt the metal material around the electrode without turning the furnace body. The distance between the metal material and the electrode E can be estimated by monitoring the magnitude of the current flowing through the electrode E. In this type of electric furnace, the distance between the electrode E and the metal material is usually constant. Feedback control based on the current value is performed. Therefore, if the melting of the metal material around a certain electrode is slower than the surrounding of the other electrode, the height of the electrode becomes higher than that of the other electrode. This is detected as the height of the grip 30 by the grip position detector 24. Then, in the control unit 40 to which the information is input from the gripping position detection unit 24, it is determined that the furnace body is not turned while the height difference between the electrodes is larger than a predetermined reference. That's fine. In this case, as an index for determining whether or not the furnace body can be swung, it is necessary to accurately estimate the height position of each electrode E based on the reading value of the gripping position detection unit 24. It is important to accurately know the length under the neck of each electrode E using the grip position detection unit 24. From this point of view, the length of the neck of the electrode E is estimated with high accuracy using the electrode length measuring device 1 to accurately determine whether or not the furnace body can be swung in the swivel electric furnace. Melting can proceed with high efficiency.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, the limit switch 18 is used as the lowering detection unit for detecting the lowering of the container 14, but the present invention is not limited to this as long as the lowering of the container 14 can be detected, and an optical sensor is installed on the installation surface P. It can be set as the form which detects a part of container 14 which descends.

DESCRIPTION OF SYMBOLS 1 Electrode measuring apparatus 10 Electrode contact part 12 Refractory 14 Container 14a Guide surface 15 Sand (heat resistant powder)
16 Coil spring (biasing means)
17 Standing wall 18 Limit switch (Descent detection part)
18a Strike 19 Inclination restricting part 20 Drive part 22 Lifting part (hydraulic cylinder)
24 Gripping position detector (linear encoder)
30 Gripping part 40 Control part 50 Base 51a-51c Mounting hole 52a-52c Mounting piece E Electrode E1 Electrode tip G Gap P Installation surface

Claims (7)

A gripping part for gripping the electrode;
An elevating part for elevating and lowering the grip part;
A gripping position detector for detecting the vertical position of the gripper;
A container that has an opening through which the electrode can enter and that descends when a force is applied to the bottom surface from above, and a descent detector that detects the descent of the container; An electrode contact portion filled with heat-resistant powder particles having a high melting point in the container;
Based on the amount of change in the position of the gripping part detected by the gripping position detection part until the electrode is lowered from the reference position by the lifting part and the drop detection part detects the descent of the container, An electrode length measuring apparatus comprising: a control unit that detects a length of the electrode from a position of the gripping unit to a lower end.   The electrode length measuring apparatus according to claim 1, wherein the heat-resistant granular material is sand.   3. The electrode length measuring device according to claim 1, wherein the lowering detection unit can be attached to a plurality of positions around an axis through which the electrode enters the container.   The electrode length measuring device according to any one of claims 1 to 3, wherein the lowering detection unit includes a limit switch. The container integrally has a guide surface extending downward, and is supported above the installation surface via a biasing means that biases the container upward,
On the installation surface, a standing wall facing the guide surface is erected,
Either one of the guide surface and the standing wall is provided with an inclination restricting portion that restricts the inclination of the guide surface with respect to the standing wall by contacting the other surface at a portion facing the other surface. The electrode length measuring device according to any one of claims 1 to 4, wherein the electrode length measuring device is provided.   The inclination restricting portion is made of a rod-shaped member that is fixed along the standing wall and has a circular cross section in the vertical direction, and is narrower than the diameter of the cross-section of the rod-shaped member between the rod-shaped member and the guide surface. The electrode length measuring device according to claim 5, wherein a gap is provided.   2. A furnace body containing a metal material can be swiveled with respect to an axis of an electrode, and is provided with a swivel electric furnace that melts the metal material by causing a discharge through the electrode. The electrode length measuring apparatus according to any one of 6.

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