JP6153765B2 - Vacuum arc melting device - Google Patents

Description

  The present invention relates to a vacuum arc melting apparatus that melts a sample of metal, mineral, etc. by generating an arc in a vacuum vessel, and more particularly to a vacuum arc melting apparatus that can easily adjust and maintain the distance between an electrode and a sample. .

  The vacuum arc melting method is to place a sample of metal (steel, mineral, alloy) etc. on a hearth and store it in a vacuum vessel, and insert an electrode in the vacuum vessel in an airtight manner. A DC voltage is applied between them to generate an arc discharge, and the sample is melted using the arc heat, which is known as a vacuum arc melting apparatus.

  In the vacuum arc melting process, obtaining a uniform and constant dissolution rate is most important for the quality of the sample after dissolution and solidification, and for this purpose, it is necessary to control the vacuum arc energy that is a heat input source to be constant. is there. In particular, since the amount of arc thermal energy applied to the sample varies greatly depending on the distance between the electrode and the sample molten pool surface (arc gap), it can be said that control of this arc gap is the most important.

  However, the arc gap between the electrode tip and the sample molten pool (metal pool) liquid level constantly fluctuates due to dissolution of the solid sample. In addition, this further changed the melting rate, resulting in fluctuations in the arc gap, and the control thereof was extremely difficult. In order to avoid such a problem, a vacuum arc melting apparatus has been developed that can easily keep the distance between the sample and the electrode constant and can smoothly dissolve the sample.

  The outline is shown below as prior art. For example, in a vacuum arc melting apparatus in which a sample 2 is placed in a vacuum vessel and an arc is generated between the sample 4 and an electrode 4 hermetically inserted in the vacuum vessel to melt the sample. A cylindrical member 8 that is concentrically fixed to the outer portion of the vacuum vessel of the electrode and has an outer diameter screw formed on the outer periphery, and an inner diameter screw that engages with the outer diameter screw of the cylindrical member are formed on the inner circumference. And a cylindrical positioning stopper 7 rotatably held by the electrode, and a fixed stopper 5 which is airtightly fixed to the insertion portion of the electrode of the vacuum vessel and contacts the positioning stopper. A vacuum arc melting apparatus is disclosed. (Refer to Patent Document 1 and reference description in FIG. 2)

  In the vacuum arc melting apparatus having the above configuration, the position of the positioning stopper in the axial direction with respect to the electrode can be finely adjusted by rotating the positioning stopper 7 screwed to the cylindrical member fixed to the electrode. Therefore, the positioning stopper is brought into contact with the fixed stopper 5 fixed to the vacuum vessel side, thereby finely adjusting the distance (arc gap) between the sample placed in the vacuum vessel and the tip of the electrode. Can be kept at a proper interval.

  A mechanism using the cylindrical member 8 for fine adjustment of the vertical movement of the electrodes of the vacuum arc melting apparatus as described above, the positioning stopper 7 screwed to the cylindrical member 5 and the fixed-side stopper (also serving as the spherical axis) will be described below. This is referred to as a position adjustment mechanism 17.

JP 7-318257 A Japanese Utility Model Publication No. 6-22361

  However, in the conventional vacuum arc melting apparatus configured as described above, since the arc position adjustment mechanism is a function for fine adjustment, the amount of vertical movement of the electrode with respect to the rotation operation performed using the positioning stopper Must be small and small. As described above, since the amount of arc heat energy applied to the sample greatly varies depending on the distance between the electrode and the sample molten pool surface (arc gap), it can be said that quick control of the arc gap is most important.

  After fine adjustment of the distance between the electrode and the sample and supply of sufficient arc energy, there are many situations in which it is necessary to suppress the arc energy by quickly moving away from the electrode depending on the dissolution state of the solid sample. In such a case, in the arc position adjusting mechanism described above, there is a delay in the reverse rotation due to manual gripping using the positioning stopper, and there is a delay in the operation of moving the electrode tip away from the sample. In some cases, contact between the sample and the tip of the electrode may occur, or discharge may stop during dissolution. As a result, the excess phenomenon and balance of the arc heat energy supply amount to the sample are lost, and it is difficult to obtain a product of favorable quality. The problem is how to smoothly perform the minute operation of quickly moving the electrode tip, that is, the electrode in the vertical direction.

  The present invention has been made in view of the above, and by providing an arc position adjusting mechanism that can finely adjust the distance between the sample in the vacuum vessel and the electrode tip, and can quickly move the electrode tip up and down. An object of the present invention is to provide a vacuum arc melting apparatus capable of smoothly maintaining the quality of the melting level of a sample.

  To achieve the above object, the present invention places a sample in a vacuum vessel and generates an arc between the electrode hermetically inserted in the vacuum vessel and the sample to dissolve the sample. In the vacuum arc melting apparatus, a coil spring is installed between a positioning stopper of the arc position adjusting mechanism and a fixing stopper contacting the lower side thereof.

  Since the coil spring expands and contracts the distance between the positioning stopper screwed to the electrode and the cylindrical member and the spherical axis, the expansion / contraction dimension simultaneously expands and contracts the distance between the electrode tip and the sample. . There is no limit to the number of coil springs. The coil spring may be a striated body having a similar function. There is no limitation on the spring coefficient of the coil spring, but the coil has a spring strength that can handle only the initial compression deformation against the total weight of the upper positioning stopper, cylindrical member, electrode, clamping handle, etc. supported as a spring. A spring is preferred. Further, by setting a plurality of coil springs having different spring coefficients and lengths, spring outer diameters, etc., the strength setting of the spring repulsive force can be changed according to the compressed dimensions.

  By interposing a coil spring in contact with the bottom surface of the positioning stopper, when the electrode is moved downward together with the positioning stopper, a spring repulsive force of the coil spring that constantly pushes the positioning stopper upward is generated. At the same time, the coil spring also serves as a fixed stopper for the positioning stopper, so that the positioning stopper is fixed at a fixed position by the coil spring. Subsequent screwing screw rotation of the positioning stopper can move only the electrode downward.

  Arc discharge is started after the distance between the electrode tip and the sample is set by the fine adjustment by rotating the positioning stopper as described above. At this time, the vertical fine movement can be performed quickly by adjusting the distance between the electrode tip and the sample. Adjustment is required. This quick minute movement adjustment can be performed directly by the tightening handle via the repulsive force of the coil spring. When the electrode is moved quickly downward, it is pushed down by a small distance against the repulsive force of the coil spring. On the other hand, when the electrode is quickly moved upward, it can be quickly pulled up by utilizing the repulsive force of the coil spring.

  In the vacuum arc melting apparatus, the rotation of the positioning stopper is performed by interposing a spring coil between a positioning stopper, which is an arc position adjusting mechanism for finely adjusting the distance between the electrode and the sample, and a fixing stopper. An arc position adjustment mechanism has been added that makes it possible to smoothly and quickly change the distance between the electrode and the sample when adjusting the arc energy by smoothing the minute movement in the vertical direction without being accompanied. A vacuum arc melting apparatus is provided.

  When it is necessary to finely adjust the distance between the electrode and the sample and supply sufficient arc energy and then quickly move the electrode away to suppress the arc energy, according to the present invention, the manual operation of the positioning stopper in the arc position adjusting mechanism is performed. Since reverse rotation by gripping is not required, the adverse effect of delaying the operation of moving the electrode tip away from the sample can be minimized. This prevents overmelting of the arc heat supply to the sample more than necessary and contact failure between the sample and the electrode, so that the proper arc discharge position can be maintained. It will be possible to obtain a dissolution product of favorable quality.

It is a figure which shows the cross-sectional schematic structure in the vacuum arc melting apparatus which concerns on one Embodiment of this invention. It is a figure which shows the cross-sectional schematic structure in the conventional structure of a vacuum arc melting apparatus. It is a figure which shows the cross-sectional schematic structure of only the arc position adjustment mechanism of the vacuum arc melting apparatus which concerns on one Embodiment of this invention, and shows the aspect at the time of installing two coil springs.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing a conventional vacuum arc melting apparatus and its arc position adjusting mechanism. First, a conventional arc position adjusting mechanism will be described with reference to FIG. A hearth 12 is set on the inner bottom surface of the spherical vacuum vessel 13, and a sample 2 such as metal is placed on the upper surface. Arc discharge is generated according to the distance between the electrode tip 3 and the potential applied to the sample 2, the sample 2 is arc-melted, and a sample melting pool 21 is generated in the hearth 12.

  The electrode 4 penetrates the upper part of the spherical vacuum vessel 13 and is connected to an external charge wiring. The penetrating portion between the spherical vacuum vessel 13 and the electrode 4 is hermetically fixed by the spherical shaft 5 and the spherical bearing 6, and the electrode 4 has a degree of freedom of vertical movement and a slight degree of freedom in the forward / backward / left / right rotation direction by the spherical shaft 5. The structure has a degree.

  The spherical shaft 5 covers the electrode in a cylindrical shape at the upper and lower portions, and gives the degree of freedom of movement of the electrode 4 in the vertical direction while maintaining the sealing degree by the O-ring 14. The spherical shaft 5 has a portion protruding in a cylindrical shape at the upper portion, and thus also functions as a fixing stopper for receiving and fixing the upper positioning stopper 7. The positioning stopper 7 has a cylindrical shape, has an outer diameter screw on the inner diameter side, and is screwed with an inner diameter screw on the outer diameter side of the cylindrical member 8. Since the cylindrical member 8 is in close contact with the electrode 4 in a cylindrical shape and is fixedly connected to the electrode 4 with a screw 15, the electrode 4 can move up and down together with the vertical movement of the cylindrical member 8.

  First, the cylindrical member 8 fixedly connected to the electrode 4 and the positioning stopper 7 screwed to the outer diameter of the cylindrical member 8 are moved downward together with the electrode 4 without rotating, thereby serving as a fixed stopper. The downward movement is stopped by coming into contact with the upper protrusion of 5. Thereafter, by rotating the positioning stopper 7, the cylindrical member 8 and the electrode 4 screwed with the inner diameter thereof can be moved minutely downward together.

  The vertical movement of the electrode due to the rotation of the positioning stopper 7 is the vertical movement due to the rotation of the screw that is screwed together, so that it is possible to finely move the movement amount depending on the screw diameter density. That is, the vertical movement of the electrode tip 3 can be finely adjusted, so that the distance from the sample 2 can be finely adjusted to adjust the amount of arc heat. The mechanism for finely adjusting the vertical movement of the electrode 4 as described above is the arc position adjusting mechanism 17.

  The upper part of the arc adjusting mechanism set for the electrode 4 is a clamping handle base 9 and a clamping handle 10 connected to the positioning stopper 7, and the positioning stopper 7 is rotated by gripping and rotating the clamping handle 10 made of an insulating member. Can do. By gripping and rotating the tightening handle 10, the electrode 4 can be slightly moved up and down. Similarly, by operating the tightening handle, the electrode 4 can be slightly rotated back and forth and left and right using the spherical axis 5. The uppermost portion of the electrode 4 is covered with a polyvinyl chloride insulating cover 11 and connected to an external charging facility.

  As described above, the vertical movement of the electrode 4 is a fine movement that can be finely adjusted by the rotation of the tightening handle 10 urging the rotation of the positioning stopper 7 of the arc position adjusting mechanism 17. In the case where the amount of arc heat generated in the electrode is excessive, the clamping handle 10 must be rapidly rotated in the reverse direction in spite of wanting to move the electrode tip 3 away from the sample 2 quickly. The workability was poor with the arc position adjusting mechanism 17 alone.

  In order to quickly control the amount of arc heat, the gripping rotation by manual operation of the positioning stopper 7 is limited in order to quickly move the distance between the electrode tip 3 and the sample 2 closer to or away from the sample 2. There was a situation in which the delay missed the opportunity to maintain the dissolution quality of Sample 2.

  On the other hand, it is a feature of the present invention that an arc position adjusting mechanism 17 for quickly moving the electrode 4 in the vertical direction in a timely manner in order to control the amount of arc heat is provided. 1 showing a schematic cross-sectional structure in an embodiment of a vacuum arc melting apparatus according to the present invention will be described. 1, the same reference numerals are given to portions corresponding to FIG. 2 of the conventional example, and description thereof will be omitted as appropriate.

  In FIG. 1, the electrode 4 is attached to the upper wall of the spherical vacuum vessel 13 in an airtight manner so as to be freely movable in the axial direction and tiltable via the spherical shaft 5 as in the conventional example of FIG. An arc position adjusting mechanism 17 that is a feature of the present invention is provided on the cylindrical portion of the electrode 4 protruding upward from the spherical axis 5.

  The arc position adjusting mechanism 17 according to the present invention is characterized in that a coil spring 18 is interposed between the positioning stopper 7 and the upper cylindrical protrusion of the spherical shaft 5. There are no particular restrictions on the strength, spring coefficient, and material of the coil spring 18. Moreover, not only a coil spring but the stripe body of another shape may be sufficient. The spring repulsive force of the coil spring 18 corresponds to a force that can be pushed up and moved simultaneously without rotating the positioning stopper 7 and the cylindrical member 8, the electrode 4, and the clamping handle 10 at the upper part thereof.

  The coil spring 18 is fixed in contact with the upper protrusion of the spherical shaft 5 at its lower end, and is held in contact with the lower surface of the positioning stopper 7 at its upper end. The coil spring 18 is set on the outer periphery of an insulating collar 22 that covers the electrode 4 in a cylindrical shape. The outer periphery of the coil spring 18 is surrounded and held by a cylindrical spring cover (lower part) 19 and a spring cover (upper part) 20.

  The outer circumferential diameter of the spring cover (lower part) 19 is smaller than the circumferential inner diameter of the spring cover (upper part) 20, and is configured to come into light contact with the coil spring. When the coil spring 18 is compressed, both spring covers are covered. Are overlapped so that the height dimension is reduced in accordance with the contraction of the coil spring 18.

  The function of the arc position adjusting mechanism 17 of the vacuum arc melting apparatus 1 of the present invention will be described. First, the cylindrical member 8 fixedly connected to the electrode 4 and the positioning stopper 7 screwed and joined to the outer shape of the cylindrical member 8 move downward together with the electrode 4 without rotating. Since the lower surface of the positioning stopper 7 is in contact with the upper part of the coil spring 18, the downward movement is stopped. After that, by rotating the tightening handle 10, the cylindrical member 8 and the electrode 4 screwed together with the inner diameter of the positioning stopper 7 can be moved minutely downward together. At the same time, arc melting between the electrode tip 3 and the sample 2 is performed by arc discharge.

  In the state where the arc melting is set to be feasible, there are the following technical features in starting the arc discharge. Arc discharge does not yet occur at the distance between the electrode tip 3 and the sample 2 to which a constant potential sufficient for arc discharge is set in advance. The trigger for the occurrence of arc discharge is to make the distance between the electrode tip 3 and the sample 2 slightly closer. Arc discharge is generated by obtaining as a trigger the instantaneously lowered insulating atmosphere generated between the electrode tip 3 and the sample 2.

  Once the arc discharge is started, the electrode tip 3 is quickly moved slightly upward again to avoid putting an excessive amount of arc heat into the sample, and the distance from the sample 2 is returned to and maintained at a preset position. There is a need.

  The act as a trigger for generating the arc discharge requires an instantaneous agile operation, and the structure for enabling the operation of the electrode is the structure of the arc position adjusting mechanism 17 of the vacuum arc melting apparatus 1 of the present invention. It is a characteristic part. By interposing the coil spring 18 between the lower portion of the positioning stopper 7 and the upper portion of the spherical shaft 5, the trigger action for generating the arc discharge is not performed by the complicated operation of rotating and reversely rotating the handle 10. In addition, it is possible to perform the operation instantly by a skilled pressing operation to the tightening handle 10.

  That is, the tightening handle 10 using the positioning stopper 7 of the arc position adjusting mechanism 17 is rotated to finely adjust the distance between the electrode tip 3 of the electrode 4 and the sample 2, and a potential necessary for constant arc discharge is obtained. After the charging, the electrode 4 is momentarily pushed down by a small distance against the spring repulsive force of the coil spring 18 to generate arc discharge. Immediately after that, the electrode 4 and the electrode tip 3 are pushed up to the position set instantaneously by using the spring repulsive force, and thereafter, the required amount of arc heat by the constant arc discharge can be uniformly supplied to the sample 2.

  Although the arc position adjusting mechanism 17 according to the present invention has been described with respect to the triggering action for generating arc discharge at the start of arc discharge, the electrode tip 3 is similar to the above even during general use of the vacuum arc melting apparatus. The need for an operation of bringing the sample immediately close to the sample 2 by a minute distance and returning it instantly again occurs. Even in such a case, the arc position adjusting mechanism 17 according to the present invention similarly exhibits a great ability.

  The coil spring 18 used in the arc position adjusting mechanism according to the present invention is not limited to a coil spring, and may be a striated body having another shape. A striped body such as a plate spring may be used, or a stripped body having a structure intervening under the positioning stopper 7 and having the above function may be used. The spring coefficient, material, and number are not limited, but may be set according to the weight of the electrode and the member located above the striated body, and the required amount of fine movement distance from the electrode tip to the sample. That's fine.

  Next, another embodiment of the present invention will be described. FIG. 3 is a diagram showing a schematic cross-sectional structure of the installation portion of the coil spring 18 in another embodiment of the arc position adjusting mechanism 17 of the vacuum arc melting apparatus 1 according to the present invention. This is an embodiment in which a small coil spring 23 is additionally installed inside the coil spring 18.

  For example, when the spring length of the coil spring small 23 is shorter than that of the coil spring 18, the coil spring 18 is compressed and contracted with the downward movement of the positioning stopper 7. Both coil springs are compressed and contract simultaneously. From this point of time, the spring repulsive force becomes large, and it becomes possible to make a more careful movement even when fine adjustment is performed by depressing the electrode 4 and bringing the electrode tip 3 close to the sample 2.

  Similarly, when the electrode tip 3 is moved away from the sample 2 as described in the first embodiment, it can be quickly moved away using a larger spring repulsive force.

  The spring coefficient, the length ratio, and the size ratio of the two coil springs may be arbitrarily set, and may be adapted to the required specifications. The specification required for this coil spring is the distance required from the distance between the electrode tip 3 and the sample 2 and the required arc heat capacity, and the distance at which the subtle vertical movement of the electrode 4 can be easily adjusted accordingly. It is a specification to be generated, and a coil spring specification to satisfy them may be selected. Similarly, the spring coefficient is a specification determined by the weight of a member positioned above the electrode and the coil spring, the friction coefficient between the spherical axis and the electrode, and the coil spring specification for satisfying the specification may be selected.

  As described above, the number of coil springs may be three or more, and may be a spring body such as a plate spring other than the coil spring.

  As described above, according to the vacuum earth melting apparatus of the present invention, after finely adjusting the distance between the electrode and the sample and supplying sufficient arc energy, the electrode is quickly moved away depending on the melting state of the solid sample to suppress the arc energy. When necessary, it is possible to minimize the adverse effect of delaying the operation of moving the electrode tip close to and away from the sample instantaneously. This prevents over-melting of the arc heat supply to the sample more than necessary and prevents contact between the sample 2 and the electrode 4 and maintains an appropriate arc discharge position. A molten sample can be obtained.

  Here, it is needless to say that the above-described embodiment is merely an example, and various modifications or improvements can be made without departing from the gist of the present invention.

  According to the vacuum arc melting apparatus according to the present invention, it is possible to finely adjust the distance between the electrode and the sample, and to maintain a proper arc discharge position and arc heat supply by being able to finely change instantaneously, A high quality arc melt such as metal, steel, and mineral can be obtained. The technical and economic significance of the vacuum arc melting apparatus according to the present invention is great, and the industrial utility value is extremely great.

1 ... Vacuum arc melting device 2 ... Sample (metal, steel, mineral, etc.)
3 ... Electrode tip 4 ... Electrode 5 ... Spherical axis (also serves as fixed side stopper)
6 ... spherical bearing 7 ... positioning stopper 8 ... cylindrical member 9 ... clamping handle base 10 .... clamping handle 11 .... PVC insulation cover 12 .... hearth 13 .... spherical vacuum vessel 14 .... O-ring 15 ・ ・ Screw 16 ・ ・ Threading part 17 ・ ・ Arc position adjustment mechanism 18 ・ ・ Coil spring 19 ・ ・ Spring cover (lower part)
20. ・ Spring cover (top)
21..Sample melting pool 22..Insulation collar 23..Small coil spring

Claims (1)

Wherein the inserted electrodes hermetically in a vacuum vessel by generating an arc between the mounted sample in a vacuum vessel, a vacuum arc melting apparatus for dissolving the sample,
A cylindrical member that is concentrically fixed to the outer portion of the vacuum vessel of the elongated electrode and has an outer diameter screw formed on the outer periphery;
A cylindrical positioning stopper in which an inner diameter screw threadedly engaged with an outer diameter screw of the cylindrical member is formed on the inner periphery and rotatably held by the electrode;
Wherein comprises a coil spring positioned between the spherical shaft fixed airtightly to the insertion portion of the electrode of the vacuum container and the positioning stopper,
The coil springs are a plurality of coil springs having different spring strengths and lengths,
The vertical movement distance of the fine movement of the electrode, vacuum arc melting apparatus, characterized in that caused a step in repulsive force of the coil spring.

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