Jig and method for determining service life of electrode of plasma cutting torch

Abstract

To provide a jig with a simple constitution capable of determining the service life of the electrode of a plasma cutting torch.SOLUTION: A jig 1 serves for determining a service life of an electrode 22 of a plasma cutting torch 10, and includes: a pin 2 that can be inserted into an opening 31a of a tip 30 surrounding the electrode 22 at a tip of the plasma cutting torch 10; a detection unit 5 that detects that the electrode 22 is in contact with the pin 2 inserted in the opening 31a; and a display unit 6 that displays that the contact between the pin 2 and the electrode 22 is detected by the detection unit 5. The pin 2 is configured to be insertable into the opening 31a by a predetermined length from the opening 31a toward the electrode 22.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a jig and a method for checking the life of an electrode of a plasma cutting torch.

Background Art

[0002] Conventionally, plasma cutting has been used as one of the methods for cutting metal members such as stainless steel. In plasma cutting, a high-temperature plasma arc is generated between the base material and an electrode provided at the tip of the plasma cutting torch, and the base material is cut by the heat of this plasma arc.

[0003] As the electrode of the plasma cutting torch is used, it is consumed in the longitudinal direction. When this consumption progresses and the electrode becomes shorter than a predetermined length, the amount of heat input from the plasma arc to the electrode becomes excessive, resulting in thermal damage to the electrode, or the plasma arc becomes unstable, resulting in the generation of a double arc. As a result, not only processing defects occur in the base material, but the plasma cutting torch may be damaged.

[0004] Therefore, in the case of a plasma cutting torch, it is necessary to monitor so that the electrode can be replaced at a stage before it reaches the end of its life and becomes shorter than the predetermined length. On the other hand, in the case of a plasma cutting torch, due to its structure, it is not easy to externally check the consumption status of the electrode because the periphery of the electrode is surrounded by chips. Although the consumption status of the electrode can be confirmed by disassembling the plasma cutting torch each time, this disassembling work is a heavy burden on the operator.

[0005] As a document disclosing an apparatus for checking the life of an electrode without disassembling a plasma cutting torch, for example, there is Japanese Patent Application Laid-Open No. 6-226452 (Patent Document 1). The apparatus disclosed in the Patent Document 1 is for checking the life of an electrode included in a plasma automatic processing machine that automatically performs plasma cutting, and includes a measuring means, a storage means, a comparison operation means, a comparison determination means, and a warning means. The measuring means measures the position at the center of the tip of the electrode in the plasma cutting torch. The storage means measures the position at the center of the tip of the electrode when the electrode is new and stores the measured value. The comparison operation means measures the position at the center of the tip of the electrode for each number of processing times, stores the measured value, and performs a comparison operation with the measured value of the position at the center of the tip of the new electrode. The comparison determination means compares and determines whether this comparison value is greater than the life determination value. The warning means notifies of the life when this comparison value is greater than the life determination value.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Here, from the viewpoint of reducing manufacturing costs and the risk of failure, etc., the above-described apparatus for checking the life of the electrode of the plasma cutting torch is desirably simply configured. Further, from the viewpoint of reducing the burden on the operator, the above-described method for checking the life of the electrode of the plasma cutting torch is desirably easily performed.

[0008] Therefore, the present invention has been made in view of the above points, and an object thereof is to provide a jig having a simple configuration capable of checking the life of the electrode of the plasma cutting torch, and a method for checking the life of the electrode of the plasma cutting torch that can be easily performed.

Means for Solving the Problems

[0009] The jig according to the present invention is for checking the life of the electrode of a plasma cutting torch, and includes a pin that can be inserted into an opening of a tip surrounding the electrode at the tip of the plasma cutting torch, a detection unit that detects that the electrode has come into contact with the pin inserted into the opening, and a display unit that displays that the contact between the pin and the electrode has been detected by the detection unit. In the jig according to the present invention, the pin is configured to be insertable into the opening by a predetermined length from the opening toward the electrode side.

[0010] With this configuration, the jig can notify the operator whether the electrode needs to be replaced without calculating the absolute value of the electrode consumption amount. Therefore, it is possible to provide a jig with a simple configuration that does not require various devices necessary for calculating the absolute value.

[0011] In the jig according to the present invention, the detection unit is configured by an electric circuit connected to both the pin and the electrode. In that case, it is preferable that the electric circuit detects that the electrode has come into contact with the pin when the electric circuit is conducted by the contact between the pin and the electrode.

[0012] With this configuration, it is possible to detect that the electrode has come into contact with the pin when the electric circuit is conducted by the contact between the pin and the electrode.

[0013] The jig according to the present invention may further include a base portion provided such that the pin protrudes from the main surface, and an elastic body provided on the base portion and elastically biasing the pin in a direction away from the main surface at the tip of the pin. In that case, it is preferable that the detection unit detects that the pin has been displaced by the contact between the pin and the electrode.

[0014] By configuring in this way, since the selection of the material constituting the pin is not restricted by electrical characteristics, the range of material selection for the pin can be widened. Further, by configuring in this way, when the electrode contacts the pin, the impact load received by the pin is alleviated by the elastic body, so that the risk of the pin being damaged can be effectively reduced.

[0015] In the jig according to the present invention, the detection unit may be configured by a pressure sensor.

[0016] By configuring in this way, the detection unit can be made into a simple configuration.

[0017] A method for confirming the life of an electrode of a plasma cutting torch according to the present invention includes inserting a pin configured to be insertable by a predetermined length from the opening of a tip located around the electrode at the tip of the plasma cutting torch toward the electrode side, detecting that the electrode has contacted the pin inserted into the opening, and displaying that the contact between the pin and the electrode has been detected.

[0018] By using such a method, an operator can easily confirm the life of the electrode of the plasma cutting torch.

Effect of the Invention

[0019] According to the present invention, it is possible to provide a jig with a simple configuration capable of confirming the life of an electrode of a plasma cutting torch, and a method for easily confirming the life of an electrode of a plasma cutting torch.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

BEST MODE FOR CARRYING OUT THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments illustrate a case where the present invention is applied to a manual plasma cutting torch manually operated by an operator as an example of a plasma cutting torch. In the following embodiments, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0022] (Embodiment) FIG. 1 is a schematic diagram of a jig according to an embodiment and a tip portion of a plasma cutting torch. Hereinafter, with reference to FIG. 1, first, a schematic configuration of the tip portion of the plasma cutting torch 10 will be described, and then the jig 1 according to the present embodiment will be described.

[0023] As shown in FIG. 1, the plasma cutting torch 10 includes at least an electrode rod 20 and a tip 30 at its tip portion. The electrode rod 20 and the tip 30 are arranged in this order from the inside to the outside in the radial direction of the electrode rod 20. The axis of the tip 30 coincides with the axis of the electrode rod 20.

[0024] The electrode rod 20 includes an electrode base material 21 and an electrode 22. The electrode base material 21 has a substantially cylindrical shape. A concave portion is provided at the end of the electrode base material 21 located on the tip side of the plasma cutting torch 10. The electrode base material 21 is a part for holding the electrode 22 mounted in the concave portion. The electrode 22 has a substantially cylindrical shape. The electrode 22 is inserted into the concave portion of the electrode base material 21. The electrode 22 is a part that generates a plasma arc between itself and the base material when power is supplied thereto.

[0025] The electrode base material 21 is made of, for example, copper or a copper alloy. The electrode 22 is made of a high melting point metal material such as, for example, hafnium or zirconium.

[0026] The electrode 22 is consumed in its longitudinal direction as the plasma cutting torch 10 is used. When this consumption progresses and the electrode 22 becomes shorter than a predetermined length, the electrode 22 is replaced with a new one as having reached the end of its life.

[0027] The tip 30 is a part having a substantially cylindrical shape. The tip 30 is located at the tip of the plasma cutting torch 10, surrounding the tip-side portion of the electrode base material 21 and the electrode 22.

[0028] One end of the tip 30 located on the tip side of the plasma cutting torch 10 has a convex portion 31 formed in a convex shape. An opening 31a is provided in the convex portion 31.

[0029] The inner diameter of the opening 31a is configured to be smaller than the inner diameter of the remaining portion of the tip 30. Also, the inner diameter of the opening 31a is configured to be smaller than the diameter of the electrode 22. The plasma gas passes through the inner space of the tip 30 configured in this way and is ejected to the outside from the opening 31a in a state of being at a high temperature and having an increased flow rate.

[0030] The jig 1 according to this embodiment includes a pin 2, a base portion 3, an elastic body 4, an electric circuit 5, and a display portion 6. As will be described in detail later, the jig 1 is used to check the life of the electrode 22 of the plasma cutting torch 10.

[0031] The pin 2 is provided on the base portion 3 so as to protrude from the first main surface 3a which is the main surface of the base portion 3. The pin 2 has a pointed tip protruding from the first main surface 3a. The pin 2 is preferably made of, for example, a hard and conductive metal material. Thereby, the risk of the pin 2 being damaged can be reduced, and the electrical connection of the electric circuit 5 as a detection portion which will be described in detail later can be realized. In this embodiment, the pin 2 made of stainless steel is used.

[0032] The pin 2 is configured to be insertable into the opening 31a by a predetermined length (see the dimension L in FIG. 4 described later) from the opening 31a of the chip 30 toward the electrode 22 side. This predetermined length means that for an electrode 22 having a consumption amount less than the consumption amount at which it is determined that the life has been reached (that is, the state where replacement is required) (hereinafter, this consumption amount is also referred to as the consumption limit amount), the pin 2 inserted into the opening 31a can contact the electrode 22, and for an electrode 22 having a consumption amount equal to or more than the consumption limit amount, the pin 2 inserted into the opening 31a cannot contact the electrode 22.

[0033] The base portion 3 is formed of a flat plate-like member having a first main surface 3a and a second main surface 3b located on the side opposite to the first main surface 3a. A concave portion 3a1 is provided on the first main surface 3a. The pin 2 protrudes from the center of the bottom surface of the concave portion 3a1 in a direction perpendicular to the bottom surface. The concave portion 3a1 constitutes a receiving portion for receiving the convex portion 31 of the chip 30 described above. Note that the shape of the base portion 3 is not particularly limited to being flat, and can be appropriately changed.

[0034] The material of the base portion 3 is not particularly limited, and is formed of, for example, a metal material or a resin material.

[0035] An elastic body 4 is provided in the base portion 3. One end of the elastic body 4 is embedded in the base portion 3 so as to abut on a portion on the base side of the pin 2. The elastic body 4 elastically biases the pin 2 in a direction away from the first main surface 3a of the pin 2. In the present embodiment, the elastic body 4 formed of a conductive metal coil spring is used.

[0036] A conductive member 3c is provided in the base portion 3 so as to fill the space between the other end of the elastic body 4 and the second main surface 3b of the base portion 3. The conductive member 3c defines a part of the second main surface 3b. The other end of the elastic body 4 abuts on the conductive member 3c.

[0037] The electric circuit 5 includes a power source 5a and a pair of first connection wirings 5b and second connection wirings 5c extending from the power source 5a.

[0038] The power source 5a may be a plasma cutting power source used to supply power to the electrode 22, which is built in a plasma cutting device including the plasma cutting torch 10, or an external power source. In the present embodiment, the plasma cutting power source is used as the power source 5a.

[0039] The first connection wiring 5b is constituted by, for example, an electric cable. The first connection wiring 5b is connected to the conductive member 3c. Thereby, the electric circuit 5 is connected to the pin 2 via the conductive member 3c and the elastic body 4 made of a conductive material. In the present embodiment, an electric cable connected to the base material side when performing plasma cutting is used as the first connection wiring 5b. Note that the first connection wiring 5b is not particularly limited to being connected to the conductive member 3c, and may be connected to the pin 2 or the elastic body 4.

[0040] The second connection wiring 5c is constituted by, for example, an energization component such as an electric cable provided inside the plasma cutting torch 10. Thereby, the electric circuit 5 is connected to the electrode 22 via the energization component.

[0041] The thus configured electric circuit 5 constitutes a detection unit that detects the contact of the electrode 22 with the pin 2. More specifically, when the electrode 22 comes into contact with the pin 2, the electric circuit 5 is electrically connected. Thereby, the electric circuit 5 detects that the electrode 22 has come into contact with the pin 2.

[0042] The display unit 6 is connected to the electric circuit 5. The display unit 6 displays that the contact between the pin 2 and the electrode 22 has been detected by the electric circuit 5. More specifically, when the electric circuit 5 is electrically connected due to the above contact, the display unit 6 gives a predetermined display to the operator.

[0043] As the display unit 6, for example, a monitor or an LED lamp or the like is used. Note that the display unit 6 is not particularly limited to these and can be variously changed. In the present embodiment, as the display unit 6, a monitor connected to the above-described power source for plasma cutting is used.

[0044] FIG. 2 is a flowchart for explaining the flow of a method for confirming the life of the electrode of the plasma cutting torch using the jig shown in FIG. 1. FIG. 3 is a schematic diagram for explaining the state in which the jig shown in FIG. 1 and a plasma cutting torch having an electrode with a consumption amount less than the consumption limit amount are set in the jig. FIG. 4 is a schematic diagram for explaining the state in which the jig shown in FIG. 1 and a plasma cutting torch having an electrode with a consumption amount greater than or equal to the consumption limit amount are set in the jig. Next, with reference to FIGS. 2 to 4, a method for confirming the life of the electrode 22 of the plasma cutting torch 10 using the jig 1 will be described.

[0045] As shown in FIG. 2, when confirming the life of the electrode 22 of the plasma cutting torch 10 using the jig 1, first, in step S1, the tip of the plasma cutting torch 10 is set on the base portion 3 of the jig 1. More specifically, the convex portion 31 located at the tip of the chip 30 is inserted into the concave portion 3a1 provided on the first main surface 3a of the base portion 3. Thereby, the pin 2 of the jig 1 penetrates through the opening 31a of the chip 30 and enters the space inside the chip 30.

[0046] As shown in FIGS. 2 and 3, when the consumption amount of the electrode 22 is less than the consumption limit amount, the tip of the pin 2 is brought into contact with the electrode 22. By conducting the electric circuit 5 in this way, in step S2, the above contact is detected by the electric circuit 5.

[0047] As shown in FIG. 2, when the contact between the pin 2 and the electrode 22 is detected by the electric circuit 5 in step S2 (when YES in step S2), in step S3, the fact that the contact has been detected is displayed on the display unit 6.

[0048] On the other hand, as shown in FIGS. 2 and 4, when the consumption amount of the electrode 22 is greater than or equal to the consumption limit amount, the tip of the pin 2 does not contact the electrode 22, and as a result, the electric circuit 5 is not conducted. That is, in this case, in step S2, the contact between the pin 2 and the electrode 22 is not detected by the electric circuit 5.

[0049] As shown in FIG. 2, when the contact between the pin 2 and the electrode 22 is not detected by the electric circuit 5 in step S2 (when NO in step S2), in step S4, the fact that the contact has not been detected is displayed on the display unit 6.

[0050] As described above, when it is detected that the electrode 22 contacts the pin 2 and that fact is displayed, the operator can confirm that the consumption amount of the electrode 22 is less than the consumption limit amount. When the consumption amount of the electrode 22 is less than the consumption limit amount, the operator can determine that the electrode 22 can continue to be used. On the other hand, when the electrode 22 does not contact the pin 2 and that fact is displayed, the operator can confirm that the consumption amount of the electrode 22 is greater than or equal to the consumption limit amount. When the consumption amount of the electrode 22 is greater than or equal to the consumption limit amount, the operator can determine that the electrode 22 has reached the end of its life. In this case, the electrode 22 is replaced by the operator with a new one.

[0051] In this way, by using the method for confirming the life of the electrode of the plasma cutting torch according to the above-described embodiment, an operator can easily confirm the above life.

[0052] Here, in the jig 1 according to the present embodiment, as described above, by detecting that the pin 2 configured to be insertable into the opening 31a by a predetermined length from the opening 31a of the chip 30 toward the electrode 22 side has contacted the electrode 22, it is indicated that the consumption amount of the electrode 22 is less than the consumption limit amount (that is, the electrode 22 has not reached the end of its life), and the operator is informed by the display unit.

[0053] With this configuration, the jig 1 can inform the operator whether the electrode 22 has reached the end of its life without calculating the absolute value of the consumption amount of the electrode 22. As a result, in the jig 1, there is no need to provide a device for calculating the absolute value (for example, a device for storing the initial position and the current position in the length direction of the electrode 22, an arithmetic device for comparing and calculating these two positions, or a control device for determining whether the electrode needs to be replaced based on this comparison and calculation value, etc.), and thus the configuration of the jig 1 can be simplified.

[0054] Therefore, by using the jig 1 according to the present embodiment, it is possible to confirm the life of the electrode of the plasma cutting torch with a simple configuration.

[0055] Further, in the jig 1 according to the present embodiment, as described above, an elastic body 4 that elastically biases the pin 2 in a direction away from the first main surface 3a is provided on the base portion 3.

[0056] With this configuration, when the electrode 22 contacts the pin 2, the impact load received by the pin 2 is relaxed by the elastic body 4. Therefore, the risk of the pin 2 being damaged can be effectively reduced.

[0057] Furthermore, in the jig 1 according to the present embodiment, as described above, a concave portion 3a1 for receiving the convex portion 31 located at one end of the chip 30 is provided on the first main surface 3a of the base portion 3.

[0058] By configuring in this way, when the tip of the plasma cutting torch 10 is set on the base portion 3, the side surface of the concave portion 3a1 functions as a guide portion for moving one end of the chip 30 along the length direction of the pin 2. Also by this, the risk of the pin 2 being damaged can be effectively reduced.

[0059] Also, in the jig 1 according to the present embodiment, as described above, a plasma cutting power source is used as the power source 5a of the electric circuit 5. Similarly, an electric cable connected to the base material side when performing plasma cutting is used as the first connection wiring 5b of the electric circuit 5, and a current-carrying component such as an electric cable provided inside the plasma cutting torch 10 is used as the second connection wiring 5c.

[0060] By configuring in this way, an existing device used for plasma cutting can be diverted as a detection portion for detecting that the electrode 22 has contacted the pin 2. Also in this regard, the configuration of the jig 1 can be simplified.

[0061] In the above-described present embodiment, the case where the pin 2 and the elastic body 4 have conductivity has been exemplified and described, but the pin 2 and the elastic body 4 may have insulating properties depending on the configuration of the detection portion.

[0062] For example, like the jig 1A according to a modification based on the present embodiment described later, when the detection portion is configured by a pressure-sensitive sensor or the like, the pin 2 and the elastic body 4 may have insulating properties. This is because it is not necessary to ensure the conduction of the electric circuit 5 due to the contact between the pin 2 and the electrode 22.

[0063] In the above-described embodiment, an external power source may be used as the power source 5a of the electric circuit 5, and an electric cable or the like prepared for the jig 1 may be used as the first connection wiring 5b and the second connection wiring 5c of the electric circuit 5.

[0064] Furthermore, in the above-described embodiment, the case where the elastic body 4 abuts on the base side portion of the pin 2 and the pin 2 is configured to be movable in its longitudinal direction has been exemplified and described. However, when the detection unit is configured by the electric circuit 5, it is not always necessary for the pin 2 to be configured to be movable in its longitudinal direction.

[0065] Here, since the consumption limit amount of the electrode of the plasma cutting torch varies depending on the type of the plasma cutting torch or the material of the electrode, etc., it may be necessary to finely adjust the length of the pin 2 that can be inserted from the opening 31a of the chip 30 toward the electrode 22 side. In this regard, in the jig 1 according to the present embodiment, the above fine adjustment can be achieved by inserting a shim between the base side portion of the pin 2 and the elastic body 4, or between the elastic body 4 and the conductive member 3c, etc. Therefore, the jig 1 can be easily customized for different types of plasma cutting torches and the like.

[0066] (Modification example) FIG. 5 is a schematic diagram for explaining a state in which a plasma cutting torch having an electrode with a consumption amount less than the consumption limit amount is set in a jig according to a modification example. Hereinafter, with reference to FIG. 5, a jig 1A according to a modification example based on the above-described embodiment will be described.

[0067] As shown in FIG. 5, the jig 1A according to the present modification example has a different configuration of the detection unit when compared with the jig 1 according to the above-described embodiment.

[0068] More specifically, in the jig 1A, the detection unit for detecting that the electrode 22 has contacted the pin 2 is configured by a pressure-sensitive sensor 7. The pressure-sensitive sensor 7 is connected to the pin 2, for example.

[0069] When the electrode 22 comes into contact with the pin 2 by inserting the pin 2 of the jig 1A configured as described above into the opening 31a of the chip 30, the pin 2 is displaced in its longitudinal direction due to this contact. When the pressure-sensitive sensor 7 detects this displacement of the pin 2, the display unit 6 connected to the pressure-sensitive sensor 7 displays that the above contact has been detected.

[0070] Even in this case, the same effects as those described in the above-described embodiment can be obtained.

[0071] Also, when configured in this way, the pin 2 and the elastic body 4 are not limited to those having conductivity, and may be configured of those having insulating properties. Therefore, since the selection of the materials constituting the pin 2 and the elastic body 4 is not restricted by electrical characteristics, it becomes possible to widen the range of selection of these materials. For example, in this modification, the pin 2 may be configured of a resin molded product or the like, and the elastic body 4 may be configured of rubber or urethane foam or the like.

[0072] (Other forms, etc.) The shapes, configurations, sizes, numbers, materials, etc. of the respective parts shown in the above-described embodiment and its modifications described above can be variously changed as long as they do not depart from the spirit of the present invention.

[0073] Also, the characteristic configurations shown in the above-described embodiment and its modifications of the present invention can be naturally combined with each other within the scope not departing from the spirit of the present invention.

[0074] Thus, the above-described embodiment and its modifications disclosed this time are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the scope of claims, and includes all changes within the meaning and scope equivalent to the description of the scope of claims.

Explanation of Reference Numerals

[0075] 1,1A jig, 2 pins, 3 base part, 3a first main surface, 4 elastic body, 5 electric circuit, 6 display part, 7 pressure sensor, 10 plasma cutting torch, 22 electrodes, 30 chip, 31a opening.

Claims

1. A jig for checking the life of an electrode of a plasma cutting torch, comprising: a pin that can be inserted into an opening of a tip that surrounds the electrode at the tip of the plasma cutting torch; a detection unit that detects that the electrode has come into contact with the pin inserted into the opening; a display unit that displays that the contact between the pin and the electrode has been detected by the detection unit; and the jig, wherein the pin is configured to be insertable into the opening by a predetermined length toward the electrode side from the opening.

2. The detection unit is constituted by an electric circuit connected to both the pin and the electrode, and the jig according to claim 1, wherein the electric circuit detects that the electrode has come into contact with the pin when the electric circuit is conducted by the contact between the pin and the electrode.

3. a base portion provided so that the pin protrudes from the main surface; and an elastic body provided on the base portion and elastically biasing the pin in a direction away from the main surface at the tip of the pin, and the jig according to claim 1, wherein the detection unit detects that the pin has been displaced by the contact between the pin and the electrode.

4. The jig according to claim 3, wherein the detection unit is constituted by a pressure-sensitive sensor.

5. inserting a pin configured to be insertable into an opening of a tip that surrounds the electrode at the tip of the plasma cutting torch by a predetermined length toward the electrode side from the opening; detecting that the electrode has come into contact with the pin inserted into the opening; and a method for checking the life of an electrode of a plasma cutting torch, comprising displaying that the contact between the pin and the electrode has been detected.

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