JP6054833B2 - Switch box for electrical discharge machining - Google Patents

Description

  The present invention relates to an electric discharge machining switch box that accommodates an electric discharge machining switch used in a wire cut electric discharge machining apparatus, and is particularly suitable for a machining liquid immersion type wire cut electric discharge machining apparatus that performs electric discharge machining in a machining liquid. The present invention relates to a switch box for electric discharge machining that can be used in the field.

  2. Description of the Related Art Conventionally, an electric discharge machining apparatus applies a predetermined pulsed electric discharge machining voltage between a work electrode and a tool electrode arranged opposite to each other with a predetermined machining gap, using an electric discharge machining liquid such as water as a machining medium. It is known as a machine tool for processing a workpiece into a desired shape by relatively moving the tool electrode and the workpiece. In the electric discharge machining apparatus, since it is difficult to install an electric discharge machining power source in the electric discharge machine main unit, the electric power source is installed in a power supply unit provided in the main unit. As the distance between the electrical discharge machining power supply and the machining gap increases, the current pulse waveform is distorted and the loss of electrical energy increases, so the power supply unit and this machine are brought as close together as possible, and only the coaxial cable between them. And so on. In Patent Documents 1 to 3, by arranging a circuit switching device using an electrical discharge machining switch as close to the machining gap as possible, the current pulse has a sharp rising and falling waveform and a high peak value. There is disclosed a wire electric discharge machining apparatus capable of supplying a high-frequency AC voltage with a gap between tool electrodes.

  In general, an electric discharge machining apparatus is a circuit switching apparatus that uses several types of circuits using an electric discharge machining switch according to the machining mode, the required machining speed, the machined surface roughness, or the machining shape accuracy. By switching between the two, the machining current pulse having a required waveform is supplied between both electrodes of the tool electrode and the workpiece, and a desired machining result is obtained. Furthermore, for reasons such as effective cooling of the machining gap and removal of machining debris, electric discharge machining is often performed by placing the workpiece in the machining tank in the electric discharge machining liquid. For example, in Patent Documents 1 to 3, a movable body that can reciprocate a piston in a cylinder body provided in a waterproof switch body, is connected to a first terminal at a rear end, and has a contact surface at a front end. A conductive movable body is provided, and the movable body is moved back and forth toward the conductor connected to the second terminal to bring the contact surface of the movable body and the conductor connected to the second terminal into contact / separation. There has been proposed an electrical discharge machining switch configured to be able to switch electrical contact between a first terminal and a second terminal. Further, these electric discharge machining switches are required to be held in a state in which the machining liquid does not enter the inside in order to maintain the function thereof. For this purpose, it is conceivable to provide a switch box for accommodating the electrical discharge machining switch in the housing and hold the electrical discharge machining switch in a gas space formed by the housing.

JP 2000-71125 A Japanese Patent Laid-Open No. 08-174339 JP 2005-279780 A

  On the other hand, as shown in Patent Documents 2 and 3, as a low-inductance connection cable for connecting the switch to a circuit outside the housing, in order to reduce the attenuation of the machining current and obtain a more desired current waveform, A core wire that is an internal conductor; an insulator film that covers the core wire; an external conductor that includes a plurality of conductive wires that are provided on the outer periphery of the insulator film; and a protective coating that covers the outer periphery of the external conductor In some cases, a coaxial cable is used.

  However, if the switch box is completely waterproof to protect the switch, the housing will be rugged and complex. In addition, if the coaxial cable as described above is used to connect the switch to a circuit outside the housing by providing a terminal in the housing by allowing the machining liquid to enter the switch box, Since the gas can move in the axial direction of the coaxial cable through gaps such as the stitches of the conductors of the external conductor of the cable, soaking the housing containing the switch in the machining fluid increases the water pressure around the housing. Accordingly, there is a possibility that air in the housing is discharged to the outside of the housing through the gap in the coaxial cable, and the machining liquid easily enters the switch. In addition, if the machining liquid is immersed in the opening of the coaxial cable in the housing, problems such as damage to the conductors in the coaxial cable and the circuit connected to the coaxial cable due to the penetration of the machining liquid into the gap of the coaxial cable occur. Therefore, it is required to prevent the machining liquid from entering the opening of the coaxial cable.

  The present invention has been made in view of such a problem, and the object thereof is to connect a switch and a circuit outside the housing using a connection cable capable of moving gas in the axial direction, such as a coaxial cable. However, an object of the present invention is to provide a switch box for electric discharge machining that can reliably hold both the switch and the opening of the connection cable in the gas space formed in the housing with a relatively simple configuration.

The switch box for electric discharge machining according to the present invention is a switch box for a machining liquid immersion type wire cut electric discharge machining apparatus, which has an opening into which a machining liquid can enter at a lower portion, and forms a gas space above the opening. A switch that is disposed in the gas space, includes a first terminal and a second terminal, and is capable of switching an electrical connection between the first terminal and the second terminal. At least one of the terminals is electrically connected to a circuit disposed outside the housing via a connection cable having a gas passage through which gas can move in the axial direction, and the switch is driven to drive the first Driving means for switching electrical connection between the second terminal and the second terminal, and the switch and the opening of the gas passage in the housing are maintained in the gas space. The gas supply means for supplying gas to the gas space, and the gas space and the low pressure space outside the housing are connected, and the gas is prevented from flowing out from the opening of the housing. Discharging means for exhausting from the gas space to the low pressure space is provided, the discharging means being below the opening of the gas passage located in the gas space and the switch, and above the opening of the housing It is characterized by having an exhaust pipe in which the open end is located .

  The “connection cable having a gas passage capable of moving gas in the axial direction” may be any connection cable as long as it has a gas passage capable of moving gas in the axial direction. As an example of such a connection cable, a core wire which is an internal conductor, an insulator film covering the core wire, an external conductor composed of a plurality of conductive wires provided on the outer periphery of the insulator film, and an external conductor The coaxial cable which has a protective film which covers the outer periphery of is mentioned. This is because a gas passage in which gas can move in the axial direction is formed by the gaps between the stitches of the plurality of conductors of the outer conductor of the coaxial cable. Moreover, the gas passage may be formed in the whole connection cable, and may be formed in a part. For example, a connection cable in which a plurality of core wires are encapsulated in a protective coating like a multi-core cable, and the plurality of core wires are exposed from the protective coating at the end and connected to desired terminals, respectively, has a plurality of core wires. In the bundled section, the gaps between the plurality of core wires have gas passages through which gas can move in the axial direction.

  In addition, the switch includes first and second terminals, and any material, structure, and component configuration can be applied as long as the electrical connection between the first and second terminals can be switched. For example, the switch may include additional terminals other than the first and second terminals, and the electrical connection may be switchable for any combination of terminals selected between the first and second terminals and the additional terminals. .

  The driving means may switch the electrical connection of the switch by any driving method as long as it drives the switch to switch the electrical connection between the first and second terminals. The structure and configuration can be adopted.

  Further, “maintaining the state in which the switch and the opening of the gas passage in the housing are located in the gas space” means that the switch is substantially waterproofed at the lower end of the opening of the gas passage in the housing. It means a state in which both lower ends of the power portions are maintained in the gas space. Moreover, the lower end of the opening of a gas passage means the lower end of the opening located most downward among the lower ends of the opening of a plurality of gas passages when there are a plurality of gas passages.

  The “low pressure space” may be any space as long as it has a lower pressure than the pressure of the gas space in the electric discharge machining switch box. For example, the low pressure space may be an atmospheric pressure space outside the machining liquid immersion type wire cut electric discharge machining apparatus.

The discharge means includes an exhaust pipe located below the opening of the gas passage located in the gas space and the switch and having an opening end positioned above the opening of the housing, and the low pressure outside the gas space and the housing. As long as the gas is exhausted from the gas space to the low-pressure space so that the gas in the gas space does not flow out from the opening of the housing, the exhaust means may be any Materials, structures and configurations can be employed.

Further, “below the opening of the gas passage and the switch” means below the lower one of the lower end of the gas passage located in the housing and the lower end of the switch to be substantially waterproofed.

In the present specification, “upper” and “lower” mean “upper” and “lower” in the vertical direction in a state where the switch box for electric discharge machining is arranged in the machining liquid immersion type wire-cut electric discharge machining apparatus, respectively. means.

In the switch box for electric discharge machining according to the present invention, the switch includes a switch body including a sealed first gas chamber and a sealed second gas chamber, and gas is supplied to the first gas chamber. When the gas in the second gas chamber is discharged, an electrical connection between the first and second terminals can be established, and the gas is supplied to the second gas chamber, When the gas is discharged from the gas chamber, the electrical connection between the first and second terminals can be released, and the driving means communicates with the first gas chamber, and connects the first gas chamber to the first gas chamber. A first air supply / exhaust pipe for supplying or exhausting gas; and a second air supply / exhaust pipe communicating with the second gas chamber and supplying or exhausting gas to the second gas chamber. The gas is supplied to the first gas chamber through the air supply / exhaust pipe and the second air supply / exhaust pipe The electrical connection of the switch is established by discharging gas from the second gas chamber, the gas is supplied to the second gas chamber by the second air supply / exhaust pipe, and the first air supply / exhaust pipe The electrical connection of the switch is released by discharging the gas from the first gas chamber, and the gas supply means is a gas supply pipe branched from the first and second supply / exhaust pipes It is preferable that the gas is supplied to the gas space through the gas supply pipe.

Moreover, in the switch box for electric discharge machining according to the present invention, the gas supply pipe supplies the gas to the gas space via a flow rate limiting unit that limits a gas flow rate, and the flow rate limiting unit is a male screw. A male screw member having a female screw part and a female screw member having a female screw part screwed into the male screw part, and allowing the gas to pass through a gap between the male screw part and the female screw part. It is preferable to limit the flow rate.

  The switch box for electric discharge machining according to the present invention is a switch box for a machining liquid immersion type wire-cut electric discharge machining apparatus, which has an opening into which a machining liquid can enter, and forms a gas space above the opening. A switch, which is disposed in a gas space and includes first and second terminals, and is capable of switching an electrical connection between the first and second terminals, wherein at least one of the first and second terminals Is connected to a circuit disposed outside the housing via a connection cable having a gas passage through which gas can move in the axial direction, and between the first and second terminals by driving the switch Driving means for switching electrical connection and gas supply means for supplying gas to the gas space so that the switch and the opening of the gas passage in the housing are maintained in the gas space To connect the gas space and the outside of the housing of the low-pressure space, as gas in the gas space from the opening of the housing does not flow out, and a discharge means for evacuating the low pressure space gas from the gas space. For this reason, even if the switch is electrically connected to a circuit outside the housing by a connection cable having a gas passage, the gas supply means can supply new gas to the gas space in the switch box, and the discharge means. Therefore, it is possible to prevent excess gas from flowing out from the opening of the housing, so that the gas can be surely prevented from being immersed in the machining fluid in both the switch and the gas passage opening of the connection cable with a relatively simple configuration. Space can be maintained. For this reason, it is possible to suitably suppress water from entering the switch and the connection cable, and to suppress the occurrence of problems caused when the machining liquid is immersed in the switch and the connection cable.

It is a block diagram of the periphery of the processing tank of the electric discharge machining apparatus which concerns on one embodiment of this invention. It is a front view of the switch box for electric discharge machining of FIG. It is a top view (BB sectional drawing) of the switch box for electric discharge machining of FIG. 2A. It is a side view (CC sectional view) of the switch box for electric discharge machining of FIG. 2A. It is a bottom view (DD sectional view) of the switch box for electric discharge machining of Drawing 2A. It is a rear view of the switch box for electric discharge machining of FIG. 2A. It is a principal part enlarged view (cutting part end view) of the switch for electrical discharge machining of FIG. 2A. It is a principal part enlarged view of the flow volume restriction | limiting part of FIG. 2A.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of an electric discharge machine to which an electric discharge machining switch can be applied. The electric discharge machine shown in FIG. 1 is a wire-cut electric discharge machine that cuts a workpiece 3 like a yarn saw by electric discharge with a wire electrode 2 that is a tool electrode. In particular, FIG. 1 shows a cross section around a processing tank of a wire cut electric discharge machine.

  As shown in FIG. 1, the electric discharge machine has a pair of upper and lower wire guide assemblies 4 that support the wire electrode 2 separately. In addition to the wire guide body, the wire guide assembly 4 incorporates a nozzle 41 for supplying a jet of processing liquid substantially coaxially in the traveling direction of the wire electrode 2 and a power supply body 42 for energizing the wire electrode. The workpiece 3 is placed on the work stand 6 in a machining tank 5 filled with an electric discharge machining liquid so as to be in contact with a metal surface electrically connected to the workpiece 3 of the work stand 6. Then, the workpiece 3 is energized through a terminal provided on the work stand 6.

  Furthermore, the electric discharge machine is an embodiment of the present invention in which a configuration for applying a high-frequency voltage by switching the voltage circuit is applied to the wire electrode 2 as required for a desired machining request. The switch box 100 is provided. The switch box 100 supplies and exhausts gas to drive the first to fourth switches 1 </ b> A to 1 </ b> D and the first to fourth switches 1 </ b> A to 1 </ b> D, as will be described in detail later, and supplies the gas into the switch box 100. The gas supply means 20 to supply and the discharge means 8 which exhausts from the gas space formed in the switch box 100 to external space (low pressure space) are attached in the processing tank 5 via an attachment member. The electric discharge machine includes a control device 18 configured by a numerical control device or the like and outputting a switching signal in response to an input from an NC program or an operation panel (not shown), and gas supply means is provided by the switching signal output from the control device 18. 20 is controlled.

  In FIG. 1, E1 and E2 are connected to a non-illustrated electric discharge machining power circuit for finishing, and E3 and E4 are connected to an electric discharge machining power circuit for rough machining (not shown). The control device 18 turns on the switches 1A and 1B and turns off the switches 1C and 1D, thereby connecting the work stand 6 and the wire guide assembly 4 to the electric discharge machining power circuit for finishing machining. By turning off 1B and turning on the switches 1C and 1D, the work stand 6 and the wire guide assembly 4 can be selectively switched and connected to the electric discharge machining power circuit for rough machining.

  2A to 2E are diagrams showing a configuration example of the switch box 100 according to the present embodiment. FIG. 2A is a front view of the switch box 100, and FIG. 2B is a plan view of the switch box for electric discharge machining in FIG. 2C is a side view of the switch box for electric discharge machining in FIG. 2A (C-C cross-sectional view), and FIG. 2D is a bottom view of the switch box for electric discharge machining in FIG. 2A (DD cross-section). 2E is a rear view of the electric discharge machining switch box of FIG. 2A. 1 and FIGS. 2A to 2E, the same elements are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  As shown in FIGS. 2A to 2E, the switch box 100 has an opening 70B into which a machining liquid can enter and a housing 70 that forms a gas space 70A above the opening 70B.

  The housing 70 includes a resin back plate 71, side plates 72 and 73, a front plate 74, a top plate 75, and a support plate 76 made of stainless steel fixed to the front plate 74 with fixing screws. The side plates 72 and 73, the front plate 74, and the top plate 75 are integrally formed, and the side plates 72 and 73 and the top plate 75 are packing members such as urethane foam so that there is no gas leakage. Is fixed to the back plate 71 with a tapping screw. As shown in FIG. 3D, the support plate 76 is partially provided at the lower end of the housing 70 in order to support branch valves 21 and 22 to be described later. A portion without 76 forms an opening 70B into which the machining liquid can enter.

  The opening 70B is not limited to the present embodiment, and the position, shape, size, and the like of the opening 70B are provided as long as they are provided below the first to fourth switches 1A to 1D and the opening of the gas passage in the housing. Any configuration may be employed.

  Further, in the gas space 70 </ b> A in the housing, there is a space between a first terminal TA electrically connected to a non-illustrated electric discharge machining power circuit for finishing and a second terminal TW electrically connected to the work stand 6. Are electrically connected to a first switch TB that is electrically connected to a non-illustrated electric discharge machining power supply circuit for finishing, and a lower wire guide assembly 4. The second switch 1B for switching the electrical connection with the connected second terminal TG, the first terminal TC electrically connected to an electric discharge machining power circuit for rough machining (not shown), and the work stand 6 A third switch 1C for switching the electrical connection between the electrically connected second terminals TW, a first terminal TD electrically connected to an electric discharge machining power circuit for rough machining (not shown), Lower wire A fourth switch 1D switching to Ido assembly 4 electrically connected to the electrical connection between the second terminal TG, respectively, are arranged.

  The first terminals TA and TB of the first and second switches 1A and 1B are electrically connected to an electric discharge machining power supply circuit for finishing machining arranged outside the housing via connection cables 91 and 92. Yes. The first terminals TC and TD of the third and fourth switches 1C and 1D are electrically connected to an electric discharge machining power circuit for rough machining disposed outside the housing via a connection cable 93. Each of the connection cables included in the plurality of connection cables 90 including the connection cables 91, 92, and 93 is a coaxial cable, and includes a core wire that is an internal conductor, an insulator film that covers the core wire, and an insulator film. The outer conductor is formed of a plurality of conductive wires knitted to each other and a protective film covering the outer periphery of the outer conductor. The plurality of connection cables 90 are connected to the first terminals TA to TD of the corresponding switches 1A to 1D, respectively, with the internal conductors exposed from the protective coating. As a result, in the plurality of connection cables 90, there is a gas passage through which gas can move in the axial direction from the gas space 70 </ b> A in the housing 70 to the electric discharge machining power circuit outside the electric discharge machine due to gaps between the conductors of the external conductor. It is formed. In addition, the part (for example, the part shown by the code | symbol H of FIG. 2A) from which the protective film of the connection cable 90 in the gas space 70A was removed becomes an opening of the gas passage located in the gas space 70A.

  In such a connection cable 90, when the machining liquid enters the gas passage formed in the connection cable 90, damage to a lead wire in the connection cable 90 or a circuit (not shown) connected to the connection cable 90, etc. May cause problems. For this reason, it is necessary to protect the machining liquid from being submerged from the opening of the gas passage of the connection cable 90.

  In the example of FIG. 2A, in order to reduce the inductance more suitably, the electric discharge machining power supply circuit (not shown) and the first terminal TA of the first switch 1A are formed by using two connection cables 91 and 92. Two connection cables 91 and 92 are collectively connected to the first terminal TA. Similarly, the two connection cables 91 and 92 are connected together at the first terminal TB of the second switch 1B. The first terminal TA of the first switch 1A and the first terminal TC of the third switch are configured in the same shape (see FIG. 3). Similarly, the first terminal TB of the second switch 1B and the first terminal TC The first terminals TD of the four switches are configured in the same shape, but in FIG. 2A, the first terminals TA, 92, 92 are connected to the first terminals TA, TB to indicate that the two connection cables 91, 92 are connected. The terminal shape of TB is modified and described. In addition, as shown in FIG. 3, you may use one connection cable in order to connect the electric discharge machining power supply circuit not shown and the 1st terminal TA of the 1st and 2nd switch 1A, 1B, TB. Further, the present invention is not limited to this embodiment, and in order to connect the electrical discharge machining power supply circuit and each terminal of each switch, any number of one or more connection cables may be used, and any connectionable cable can be connected to each connection cable. A terminal shape may be applied.

  FIG. 3 is an enlarged view (cut-face end view) of a main part showing the configuration and an example of the first switch 1A and the third switch 1C of FIG. As shown in FIG. 3, the first switch 1 </ b> A and the third switch 1 </ b> C are arranged so as to face each other and are integrated as one set switch 13.

  The first switch 1A has a cylindrical body space formed in the switch body, and includes a first terminal TA, a conductive movable contact 12A capable of reciprocating in the cylinder space, and a second terminal TW. . The first terminal TA is connected to a non-illustrated electrical discharge machining power circuit for finishing, and the second terminal TW is electrically connected to the work stand 6 via a relay terminal CW inserted through the terminal member 71E. Has been. The cylinder space is separated into two gas chambers by the movable contact 12A, and forms a sealed first gas chamber PA and a sealed second gas chamber QA. The switch body is provided with a gas supply hole a1 that communicates with the first gas chamber PA and a gas supply hole a2 that communicates with the second gas chamber QA. The gas supply holes a1 and a2 have a movable contact 12A. Are connected to the first air supply / exhaust pipe A1 and the second air supply / exhaust pipe A2, respectively. The movable contact 12A is provided with a substantially truncated cone-shaped recess 12AS on the front side (the right side in FIG. 3) of the movable contact 12A in the moving direction, and the second terminal TW is positioned at a position facing the recess 12AS of the movable contact 12A. A convex portion TWA having a truncated cone shape whose tip corresponds to the concave portion 12AS of the movable contact 12A is provided. The frustoconical taper surface of the concave portion 12AS of the movable contact 12A and the frustoconical taper surface of the convex portion TWA of the terminal TW are configured to come into contact with each other according to the forward movement of the movable contact 12A.

  The third switch 1C has a cylindrical cylinder space formed in the switch body, and includes a first terminal TC, a conductive movable contact 12C capable of reciprocating in the cylinder space, and a second terminal TW. Prepare. The first terminal TC is electrically connected to an electric discharge machining power circuit for rough machining (not shown), and the second terminal TW is electrically connected to the work stand 6. The cylinder space is separated into two gas chambers by the movable contact 12C to form a sealed first gas chamber PC and a sealed second gas chamber QC. The switch body is provided with a gas supply hole c1 that communicates with the first gas chamber PC and a gas supply hole c2 that communicates with the second gas chamber QC. The gas supply holes c1 and c2 have a movable contact 12C. Are connected to the first air supply / exhaust pipe C1 and the second air supply / exhaust pipe C2, respectively. The movable contact 12C is provided with a substantially truncated cone-shaped recess 12CS on the front side (left side in FIG. 3) in the moving direction of the movable contact 12C, and the second terminal TW is located at a position facing the recess 12CS of the movable contact 12C. A convex portion TWC having a truncated cone shape whose tip corresponds to the concave portion 12CS of the movable contact 12C is provided. The frustoconical taper surface of the concave portion 12CS of the movable contact 12C and the frustoconical taper surface of the convex portion TWC of the terminal TW are configured to come into contact with each other according to the forward movement of the movable contact 12C. Here, in the set switch 13, the second terminal TW of the switch 1A and the switch 1C is configured by a common member, but the second terminals of the switch 1A and the switch 1C may be provided separately.

  The second switch 1B and the fourth switch 1D are configured as one set switch 14 having the same configuration as the set switch 13, and the second terminal TG of the set switch 14 is inserted into the terminal member 71F. Except for being electrically connected to the wire guide assembly 4 via the relay terminal CG, the switch 1B and the switch 1A have the same configuration, and the switch 1D and the switch 1C have the same configuration.

  As shown in FIG. 2C, the set switches 13 and 14 are fixed to the back plate 71 of the housing 70 with bolts. A terminal member 71E is fitted into a through hole 71A provided in the back plate 71 of the housing 70, and the relay terminal CW that passes through the terminal member 71E is electrically connected to the second terminal TW of the set switch 13. The In addition, the terminal member 71E is coupled to the metal plate 53 electrically connected to the work stand 6 with a bolt, whereby the relay terminal CW through which the terminal member 71E is inserted is electrically connected to the metal plate 53. As a result, the second terminal TW and the work stand 6 are electrically connected.

  Similarly, a terminal member 71F is fitted in the through hole 71B provided in the back plate 71 of the housing 70, and the relay terminal CG inserted through the terminal member 71F is electrically connected to the second terminal TG of the set switch 13. Is done. Further, the terminal member 71F is connected to the metal plate 54 electrically connected to the lower wire guide assembly 4 with a bolt, whereby the relay terminal CG inserted through the terminal member 71F is electrically connected to the metal plate 54. Is done. Thereby, the second terminal TG and the lower wire guide assembly 4 are electrically connected.

  The present invention is not limited to this embodiment, and as long as it has a function of switching a desired electric discharge machining power supply circuit, the switch mechanism as described above may use any number of switches in any combination. Further, when the switch mechanism is configured using a plurality of switches, the plurality of switches may be formed integrally or separately.

  The switch box 100 is configured to supply gas to the gas space 70A so that the first to fourth switches 1A to 1D and the opening of the gas passage in the housing 70 are positioned in the gas space 70A. Is provided. This gas supply means 20 drives the first to fourth switches 1A to 1D to switch the electrical connection between the first terminals TA, TB, TC, TD and the second terminals TW, TG. It also has the role of

  The gas supply means 20 is a pressure air supply source configured to selectively send air of a predetermined pressure to the first to fourth switches 1A to 1D in response to a switching signal from the control device 18, A plurality of first air supply / exhaust pipes A1, B1, and C1 respectively connected to a first gas chamber PA to PD of a pump (not shown), a valve (not shown), and the first to fourth switches 1A to 1D. , D1, second supply / exhaust pipes A2, B2, C2, D2 connected to the second gas chambers QA to QD of the first to fourth switches 1A to 1D, respectively, and the first supply / exhaust pipe A branch valve 27 provided on the path of C1, D1 and the second supply / exhaust pipes A2, B2, and a path of the first supply / exhaust pipe A1, B1 and the second supply / exhaust pipes C2, D2 are provided. Branch valve 28 and first and second air supply / exhaust pipes A1, A2, B1, B2, C1, C2, 1, a gas which is branched through the branch valve 27 from D2 comprises a gas supply tubes 61 and 62 respectively supply the gas space 70A.

  The first air supply / exhaust pipes C1, D1 and the second air supply / exhaust pipes A2, B2 are integrated into one air supply / exhaust pipe by the first branch valve 21, and the branch valve 21 and a pump (not shown) are connected to each other. The space is configured as one air supply / exhaust pipe 23. Similarly, the first air supply / exhaust pipes A1, B1 and the second air supply / exhaust pipes C2, D2 are integrated into one air supply / exhaust pipe by the second branch valve 22, and the branch valve 22, a pump (not shown), A single air supply / exhaust pipe 24 is formed between the two. Without being limited to this embodiment, the first air supply / exhaust pipe and the second air supply / exhaust are respectively provided to the first gas chambers PA to PD and the second gas chambers QA to QD of the first to fourth switches 1A to 1D. Any configuration may be adopted as long as it is a configuration capable of sucking and exhausting gas by connecting pipes. For example, the switches 1A to 1D and the pump are respectively connected to the independent first supply / exhaust tubes A1, B1, C1, and D1. And the second air supply / exhaust pipes A2, B2, C2, and D2.

  The gas supply means 20 operates an air pump (not shown) and a plurality of valves in response to a switching signal from the control device 18, and from the second air supply / exhaust pipes A2, B2, C2, and D2 to the second gas supply hole a2. , B2, c2, d2 to supply air of a predetermined pressure to the second gas chambers QA to QD, and the first gas supply holes a1, B1, C1, D1 through the first gas supply holes a1, Movable to release the electrical connection between the first terminals TA, TB, TC, TD and the second terminals TW, TG by discharging the gas in the first gas chambers PA to PD via b1, c1, d1. The contact 12 is moved to supply air to the first gas chambers PA to PD through the first gas supply holes a1, b1, c1, and d1, and the second gas supply holes a2, b2, c2, The gas is discharged from the second gas chambers QA to QD through d2. And the first terminal TA, TB, TC, TD and a second terminal TW, moves the movable contact 12 to establish an electrical connection TG.

  The first switch 1A in FIG. 3 will be described in more detail as an example. The movable contact 12A moves to the right in FIG. 3 in accordance with the inflow of a gas having a predetermined pressure from the first gas supply hole a1, and is movable. The electrical connection between the first terminal TA and the second terminal TW is established by the contact between the frustoconical tapered surface of the concave portion 12AS of the contact 12A and the frustoconical tapered surface of the convex portion TWA of the second terminal TW. Is done. Further, the movable contact 12A moves to the left in FIG. 3 in response to the inflow of a gas having a predetermined pressure from the second gas supply hole a2, and the frustoconical tapered surface of the concave portion 12AS of the movable contact 12A and the first When the frustoconical tapered surface of the convex portion TWA of the two terminal TW is separated, the electrical connection between the first terminal TA and the second terminal TW is released. Further, here, in the first to fourth switches 1A to 1D, the atmospheric pressure at the time of gas supply is about 400 kPa, and the discharged gas is discharged from the gas chamber by the movement of each movable contact 12A to 12D. It shall be released to the atmosphere through the exhaust pipe.

  In each switch, the gas supply means 20 is configured such that the first terminals TA to TD and the second terminals TW and TG are maintained when the electrical connection between the first terminals TA to TD and the second terminals TW and TG is maintained. The first gas chambers PA to PD are maintained at a higher atmospheric pressure than the second gas chambers QA to QD so that the contact state between them can be maintained, and the first terminal and the second terminal are not electrically disconnected. In the case of maintaining, the first gas chambers PA to PD are maintained at a lower pressure than the second gas chambers QA to QD so that the state where the first terminal TA and the second terminal TW are separated can be maintained. Be controlled.

  In addition, the electric discharge machining power supply circuit is always connected to the electric discharge machining power supply circuit for rough machining by turning off the first and second switches 1A and 1B and turning on the third and fourth switches 1C and 1D. Or a state in which an electrical discharge machining power supply circuit for finishing machining is connected by turning on the first and second switches 1A, 1B and turning off the third and fourth switches 1C, 1D. Is maintained. Therefore, one of the air supply / exhaust pipes A2, B2, C1, D1 connected to the first branch valve 21 and the air supply / exhaust pipes A1, B1, C2, D2 connected to the second branch valve 22 is always gas. Supply is performed, and the other is controlled so as to discharge gas.

  The gas supply pipes 61 and 62 are connected to the first and second supply / exhaust pipes A1, A2, B1, B2, C1, C2, D1, and D2 via branch valves 27 and 28 provided on the path. The gas branched from the second air supply / exhaust pipes A1, A2, B1, B2, C1, C2, D1, and D2 is supplied to the gas space 70A.

  As described above, the pressure of the gas supplied to the first to fourth switches 1A to 1D via the first and second air supply and exhaust pipes A1, A2, B1, B2, C1, C2, D1, and D2 is About 400 kPa. Further, since the electric discharge machine according to the present embodiment is installed in the atmospheric pressure space, the atmospheric pressure in the gas space 70A in the housing 70 is the sum of the atmospheric pressure and the water pressure accompanying the water depth of the housing 70 in the machining liquid. It is about 105 kPa. In addition, the air supply / exhaust pipe 23 in which the first air supply / exhaust pipes C1, D1 and the second air supply / exhaust pipes A2, B2 are integrated and the gas supply pipe 61 branched from the air supply / exhaust pipe 23 have substantially the same pressure, The supply / exhaust pipe 24 integrating the first supply / exhaust pipes A1, B1 and the second supply / exhaust pipes C2, D2 and the gas supply pipe 62 branched from the supply / exhaust pipe 24 have substantially the same pressure. For this reason, the pressure of the gas supplied to the gas space 70A in the housing 70 through the gas supply pipes 61 and 62 is 400 kPa, and the atmospheric pressure discharged from the gas space 70A through the gas supply pipes 61 and 62 is about 105 kPa. It becomes.

  That is, in this embodiment, the pressure difference (400 kPa−105 kPa = 295 kPa) between the pressure of the pressurized gas supplied to the gas space 70A via the gas supply pipes 61 and 62 and the pressure of the gas space 70A is equal to the gas space 70A. The pressure of the gas supplied and exhausted by the gas supply means 20 to the gas space 70A is controlled so as to be larger than the pressure difference (105 kPa-100 kPa = 5 kPa) between the air pressure and the air pressure at the exhaust destination. For this reason, the gas supply means 20 supplies gas to one gas chamber of the first to fourth switches via the first or second air supply / exhaust pipes A1, A2, B1, B2, C1, C2, D1, D2. Gas supplied to the gas space 70A by one of the gas supply pipes 61 and 62 even when the gas is discharged from the other gas chamber of the first to fourth switches. Since the amount becomes larger than the amount of gas discharged from the gas space 70A by the other of the gas supply pipes 61 and 62, the supply of gas to the gas space 70A can be preferably continued.

  Further, as in the present embodiment, the gas supply means 20 includes gas supply pipes 61 and 62 branched from the first or second air supply / exhaust pipes A1, A2, B1, B2, C1, C2, D1, and D2. When gas is supplied to the gas space 70A via the gas supply pipes 61 and 62, a part of the gas for driving the switches 1A to 1D is supplied to and exhausted from the gas space 70A. The control of the gas supply / exhaust amount to the space 70A can be made common with the control of the gas supply / exhaust amount to the switches 1A to 1D, and it is not necessary to provide a gas supply pump separately from the switch driving pump. The gas can be supplied into the housing with a simple configuration.

  In addition, according to the present embodiment, one of the first air supply / exhaust pipes A1 to D1 and the second air supply / exhaust pipes A2 to D2 is always pressurized so that gas can be supplied and the other is controlled to be able to discharge gas. In addition, the amount of gas supplied from one side is larger than the amount of gas discharged from the other side. For this reason, by supplying and discharging the gas using the gas supply pipes 61 and 62 branched from both the first supply / exhaust pipes A1 to D1 and the second supply / exhaust pipes A2 to D2, respectively, No matter which of the air supply / exhaust pipes A1 to D1 or the second air supply / exhaust pipes A2 to D2 supplies or discharges gas, the other exhaust amount is subtracted from one supply amount of the gas supply pipes 61 and 62. The gas of the minute can be stably supplied to the gas space 70A. Therefore, the risk that the water level of the machining liquid in the housing 70 rises can be reduced as compared with the case where gas is intermittently supplied to the gas space 70A.

  Further, the gas supply pipes 61 and 62 include a flow restriction unit 60 that restricts the gas flow rate, and supplies gas to the gas space 70 </ b> A via the flow restriction unit 60.

  FIG. 4 shows a flow rate restricting unit 60 provided in the gas supply pipe 61 branched from the branch valve 27. 4 is a cross-sectional view of the flow restricting unit 60, an upper right view of FIG. 4 is an EE cross-sectional view of the upper left view of FIG. 4, and a lower left view of FIG. 4 is orthogonal to the upper left view of FIG. 4 is a cross-sectional view taken along the line F-F in the lower left view of FIG. 4. As shown in FIG. 4, the flow restricting portion 60 is a rod-shaped member that is a female screw member having a tip screw 66 that is a male screw member having a male screw portion 66A and a female screw portion 64A that is screwed into the male screw portion 66A. 64, and the gas flow rate is limited by allowing the gas to pass through the gap between the male screw portion 66A and the female screw portion 64A. Here, the nominal diameter of the female screw portion 64A and the male screw portion 66A is M5.

  The rod-shaped member 64 is a hexagonal rod-shaped member formed with a female screw portion 64A so as to penetrate the inside, and is provided with a slit 64B having a width of 1.5 mm and a depth of 1 mm at one end, and the slit 64B A tip screw 66 is screwed with an washer 65 sandwiched from an end provided with. A connecting screw 63 having a through hole formed therein is screwed into the other end of the rod-shaped member 64, and the connecting screw 63 is connected to the gas supply pipe 61 by a connector 61C.

  The gas passing through the gas supply pipe 61 passes through the connector 61C, the connection screw 63, and the through hole in the rod-shaped member 64, and further between the male screw portion 66A of the tip screw 66 and the female screw portion 64A of the rod-shaped member 64. It passes through a spiral flow path constituted by the gap, passes through a flow path formed between the slit 64B and the washer 65, and is supplied from the supply port 61A. In addition, the flow rate limiting unit 60 provided in the gas supply pipe 62 has the same structure as the flow rate limiting unit 60 provided in the gas supply pipe 61.

  As described above, when the flow rate restriction unit 60 is provided in the gas supply pipes 61 and 62 and the flow rate of the gas supplied to the gas space 70A is restricted, an excessive amount of gas is supplied from the supply ports 61A and 62A. This makes it easy to stably maintain the amount and pressure of the gas in the gas space 70A. Further, by restricting the flow rate of the gas supplied to the gas space 70 </ b> A, the pressure in the gas supply pipes 61 and 62 can be suitably maintained, and is connected to the gas supply pipes 61 and 62 via the branch valve 27. The pressures of the first and second air supply / exhaust pipes A1, A2, B1, B2, C1, C2, D1, D2 are also maintained, and the air supply / exhaust pipes A1, A2, B1, B2, C1, C2, D1, D2 are maintained. Therefore, it is possible to satisfactorily ensure the atmospheric pressure and the supply amount necessary for switching the first to fourth switches 1A, 1B, 1C, and 1D on and off. Further, the flow restricting unit 60 can have any configuration capable of restricting the flow rate to the gas space 70A.

  Further, as shown in the above-described embodiment, a tip screw 66 that is a male screw member having a male screw portion 66A, and a rod-like member 64 that is a female screw member having a female screw portion 64A that is screwed into the male screw portion 66A. When the gas flow rate is limited by allowing gas to pass through the gap between the male screw portion 66A and the female screw portion 64A, the gas flow rate can be limited with a simple configuration. Further, the flow rate can be easily reduced by changing the tightening degree of the tip screw 66 of the flow restricting unit 60 or selecting a tip screw having an appropriate screw length from a plurality of tip screws having different screw lengths. Can be adjusted.

  Without being limited to the present embodiment, the flow rate limiting unit 60 may have any configuration capable of limiting the flow rate of the gas supplied to the gas space 70A. In addition, as long as gas can be supplied to the gas space 70 </ b> A via the flow restriction unit 60, the flow restriction unit 60 may be provided at an arbitrary position on the path of the gas supply pipes 61 and 62. It is good also as a structure which provides the flow volume restriction | limiting part 60 only in one of these.

  The switch box 100 includes a discharge unit 8 that connects the gas space and the low-pressure space outside the housing, and exhausts the gas from the gas space to the low-pressure space so that the gas in the gas space does not flow out from the opening of the housing. .

  The discharge means 8 is located below the lower end of the opening of the gas passage of the connection cable 90 located in the gas space 70 </ b> A and the lower ends of the first to fourth switches 1 </ b> A to 1 </ b> D, and the opening 70 </ b> B of the housing 70. It is constituted by an exhaust pipe 81 whose opening end is located further upward. The exhaust pipe 81 includes a connector 82 that connects the through hole 71 </ b> C of the back plate 71 of the housing 70 and the exhaust pipe 81. As shown in FIG. 2A, when the through hole 71C connected to the opening end 81A of the exhaust pipe 81 is located in the gas space 70A, the gas in the gas space 70A passes through the exhaust pipe 81 according to the atmospheric pressure of the gas space 70A. To the outside space (low pressure space). Further, when the machining liquid enters the housing 70 and the water level becomes equal to or higher than the height W of the through hole 71C connected to the opening end 81A of the exhaust pipe 81, the machining liquid flows from the exhaust pipe 81 through the through hole 71C. After being discharged, it is temporarily stored in a processing liquid recovery unit 51 provided adjacent to the processing tank 5 and is transported from the processing liquid recovery unit 51 to a service tank (not shown) of a processing liquid by a pump or the like and recovered.

  Further, as in the present embodiment, the discharge means 8 is provided, the opening of the gas passage formed in the connection cable located in the gas space 70 </ b> A and the switches 1 </ b> A to 1 </ b> D, and the opening of the housing 70. When the water level of the machining liquid is maintained above 70B, the gas space 70A is not filled with gas more than necessary, and unnecessary machining liquid is discharged from the exhaust pipe to form the connection cable. The opening of the gas passage and the switches 1A to 1D can be protected from being immersed in the machining liquid. As a result, it is possible to prevent the machining liquid from entering the connection cable from the opening end of the connection cable and damaging the connection cable and the circuit connected to the connection cable.

  Further, as in the present embodiment, the housing is located below both the lower ends of the first to fourth switches 1A to 1D and the lower end of the opening of the gas passage of the connection cable located in the gas space 70A, and the housing When the exhaust pipe 81 having the opening end 81A connected to the gas space 70A is provided above the opening 70B of the 70, the housing 70 is more reliably disposed above the opening end 81A of the exhaust pipe 81 with a simple configuration. The gas space inside can be maintained.

  The discharge pipe 81 is configured to have a resistance that is less than or equal to the extent that the increased amount of gas in the housing 70 can be discharged out of the housing 70 as necessary and sufficient. Preferably, the discharge pipe 81 is disposed horizontally between a portion where the discharge direction is changed to the opening 81B located in the machining liquid recovery unit 51, or inclined so that the position gradually decreases to the opening 81B. Then, the machining liquid entering the discharge pipe 81 can be more smoothly discharged to the machining liquid recovery unit 51, and the liquid level of the machining liquid in the housing 70 can be more securely held at a predetermined position. Be made possible. The exhaust pipe 81 is connected to the gas space below both the lower end of each switch and the lower end of the opening of the gas passage of the connection cable located in the gas space and above the opening of the housing. If the opening end 81 </ b> A is provided, the opening end 81 </ b> B serving as a gas outlet from the exhaust pipe 81 to the outside of the housing can be allowed in design by increasing the diameter of the exhaust pipe 81 to a necessary and sufficient size. You may provide in arbitrary positions. For example, the exhaust pipe 81 is configured so that the opening end 81A connected to the gas space 70A is directed vertically upward in the processing tank (and outside the housing), near the water surface of the processing liquid in the processing tank (and outside the housing), Or you may provide the opening end 81B which is an exit of the gas from the exhaust pipe 81 above the water surface in a processing tank (and outside a housing).

  As described above, according to the present embodiment, the gas supply means 20 maintains the state where both the first to fourth switches 1A to 1D and the opening of the gas passage of the connection cable 90 are located in the gas space 70A. Since the gas can be supplied to the gas space 70 </ b> A, the first terminals TA to TD of the first to fourth switches 1 </ b> A to 1 </ b> D are electrically connected to a circuit arranged outside the housing 70 by the connection cable 90 having a gas passage. Even if it is connected to the gas space 70A, it is possible to supply more gas than the amount of gas that passes through the gas passage of the connection cable 90 and exits from the gas space in the housing 70 to the outside of the housing. Both the fourth switch 1A to 1D and the opening of the gas passage of the connection cable can be maintained in the gas space. For this reason, it is possible to suitably suppress water from entering the switches 1 </ b> A to 1 </ b> D and the connection cable, and to suppress occurrence of problems caused when the processing liquid is immersed in the switch and the connection cable.

  On the other hand, for example, in order to prevent the gas passages of the connection cables from being flooded, it is conceivable to perform waterproofing on the portions corresponding to the openings of the gas passages of the connection cables 90, respectively. However, in the method of waterproofing each connection cable 90, the work load increases as the number of connection cables 90 increases, and the waterproofing effect of the connection cable 90 is maintained due to aging as the number of waterproof portions of the connection cable 90 increases. There was a problem that the risk of being unable to do so also increased. As in the present embodiment, the gas supply means 20 maintains the state where both the first to fourth switches 1A to 1D and the opening of the gas passage of the connection cable 90 are located in the gas space 70A. When supplying gas to space 70A, even if it is a case where there are many gas passages formed by the inside of a connection cable, generation | occurrence | production of the malfunction which arises when a process liquid immerses in a connection cable suitably can be suppressed.

  Further, according to the present embodiment, since the opening 70B can be provided in an arbitrary shape in the lower portion of the housing 70, the degree of freedom in design is higher than when the housing 70 has a sealed structure, and the lower end of the housing is opened. Thus, the housing can be manufactured in a simpler and more cost-effective manner.

  Moreover, the gas supply means 20 is in a state where both the lower ends of the first to fourth switches 1A to 1D and the lower end of the opening of the gas passage of the connection cable located in the gas space 70A are located in the gas space in the housing. Any material, structure, and configuration may be employed as long as gas is supplied to the gas space so as to maintain the above. For example, the openings 61A and 62A of the gas supply pipes 61 and 62 may be arranged at arbitrary positions where gas can be supplied to the gas space 70A. As used herein, “maintaining the state where the openings of the gas passages are located in the gas space” means that when there are a plurality of gas passages, all of the lower ends of the openings of the plurality of gas passages are located in the gas space. Means to maintain.

  Moreover, you may provide the drive means which drives a switch separately from a gas supply means. When the driving means and the gas supply means are provided separately, the switch includes the first and second terminals, and any material and structure can be used as long as the electrical connection between the first and second terminals can be switched. And component configurations are applicable. For example, the switch may include additional terminals other than the first and second terminals, and the electrical connection may be switchable for any combination of terminals selected between the first and second terminals and the additional terminals. . Further, when the driving means and the gas supply means are provided separately, the driving means can switch the switch by any driving method as long as it drives the switch to switch the electrical connection between the first and second terminals. The electrical connection may be switched and any material, structure and configuration may be employed.

  Without being limited to the present embodiment, the discharging means 8 is located below the opening of the gas passage formed in the connection cable located in the gas space 70 </ b> A and the switches 1 </ b> A to 1 </ b> D and from the opening 70 </ b> B of the housing 70. Exhaust may be performed by any method capable of maintaining the water level of the machining fluid upward, and any material, structure, and configuration may be employed.

  In the above embodiment, the switch is used as a changeover switch for switching between a rough machining electrical discharge machining circuit including a low inductance wire such as a coaxial cable and a finish electrical discharge machining circuit not including a low inductance wire. Although an example has been shown, the switch of the present invention can be applied to a changeover switch of another electric discharge machining circuit in which it is desirable to provide the changeover switch as close as possible between the electrodes. For example, the switch can be used as a changeover switch between an electric discharge machining circuit that supplies a DC pulse and an electric discharge machining circuit that supplies a high-frequency AC pulse including a ferrite ring core.

A1, A2, B1, B2, C1, C2, D1, D2 Supply / exhaust pipe TA-TD First terminal TG, TW Second terminal 1A-1D Switch (Electric discharge machining switch)
2 Wire electrode 3 Work piece 4 Wire guide assembly 5 Processing tank 6 Work stand 8 Discharge means 18 Control device 20 Gas supply means 21, 22, 27, 28 Branch valve 60 Flow restriction parts 61, 62 Gas supply pipe 64 Bar-shaped member ( Female thread member)
64A Female thread part 64B Slit 66 Tip thread (Male thread member)
66A Male thread part 70 Housing 70A Gas space 70B Opening part 81 Exhaust pipe 90 Connection cable 100 Switch box (switch box for electric discharge machining)

Claims (3)

A switch box for a machining liquid immersion type wire-cut electric discharge machine,
A housing having an opening into which the machining liquid can enter at a lower portion and forming a gas space above the opening;
A switch that is disposed in the gas space, includes first and second terminals, and is capable of switching an electrical connection between the first and second terminals, and at least one of the first and second terminals A switch electrically connected to a circuit disposed outside the housing via a connection cable having a gas passage in which gas can move in the axial direction;
Drive means for driving the switch to switch electrical connection between the first and second terminals;
Gas supply means for supplying gas to the gas space so that the switch and the opening of the gas passage in the housing are maintained in the gas space;
A discharge means for connecting the gas space to the low-pressure space outside the housing and exhausting the gas from the gas space to the low-pressure space so that the gas in the gas space does not flow out from the opening of the housing; ,
The exhaust means includes an exhaust pipe having an opening end positioned below the opening of the gas passage and the switch located in the gas space and above the opening of the housing. Switch box for electrical discharge machining. The switch includes a switch body including a sealed first gas chamber and a sealed second gas chamber, and gas is supplied to the first gas chamber, and the gas in the second gas chamber Is discharged, it is possible to establish an electrical connection between the first and second terminals, gas is supplied to the second gas chamber, and gas is discharged from the first gas chamber. The electrical connection between the first and second terminals can be released;
The driving means communicates with the first gas chamber, communicates with the first gas supply / exhaust pipe for supplying or discharging the gas to the first gas chamber, and with the second gas chamber. A second air supply / exhaust pipe that supplies or discharges gas to / from the gas chamber; gas is supplied to the first gas chamber by the first air supply / exhaust pipe; By discharging gas from the gas chamber, the electrical connection of the switch is established, gas is supplied to the second gas chamber by the second air supply / exhaust pipe, and the first gas supply / exhaust pipe supplies the gas to the second gas chamber. The electrical connection of the switch is released by discharging gas from the gas chamber of 1;
The gas supply means includes a gas supply pipe branched from the first and second supply / exhaust pipes, and supplies the gas to the gas space through the gas supply pipe. The switch box for electric discharge machining according to claim 1. The gas supply pipe supplies the gas to the gas space through a flow rate limiting unit that limits a gas flow rate,
The flow restricting portion includes a male screw member having a male screw portion and a female screw member having a female screw portion screwed into the male screw portion, and the gas is provided in a gap between the male screw portion and the female screw portion. The switch box for electric discharge machining according to claim 2, wherein the flow rate of the gas is limited by allowing the gas to pass.

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