Wire Electrical Discharge Machine

Abstract

A coaxial cable (10) comprises: a core wire part (12) which is linear and which includes a core wire (16) and a tubular insulator (18) that covers the core wire (16); and a shield (14) that covers the core wire part (12). The shield (14) has a braided structure in which a plurality of bundles (20) having strands aligned therein are knit in a mesh shape. The width dimension (WD) of each of the plurality of bundles (20) is at least the radius (RD) of the core wire part (12).

Description

[Technical Field]

[0001] The present invention relates to a coaxial cable, a connectorized coaxial cable including the coaxial cable, and a wire electric discharge machine including the connectorized coaxial cable. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2013-086190 discloses a wire electric discharge machine, which includes a machining power supply (electrical discharge device) and a plurality of power supply lines (coaxial cables).

[0003] The electric discharge device generates electric discharges between the wire electrode and the workpiece (object to be machined) via multiple coaxial cables, and the object to be machined is machined in response to the electric discharges. Summary of the Invention

[0004] A coaxial cable comprises an inner conductor (core wire), an insulator, an outer conductor (shield), and a sheath. The core wire is covered by the insulator. The insulator is covered by the shield. The shield is covered by the sheath.

[0005] The core wire and the shield are connected separately to the discharge device. Therefore, in order to connect the coaxial cable to the discharge device, the core wire and the shield must be separated in advance at the tip of the coaxial cable. However, the process of separating the core wire and the shield takes time during cable manufacturing.

[0006] The present invention aims to solve the above-mentioned problems.

[0007] A first aspect of the present invention is a coaxial cable comprising a linear core portion having a core wire and a tubular insulator covering the core wire, and a shield covering the core portion, wherein the shield has a braided structure in which multiple bundles of arranged wires are braided into a mesh shape, and the width dimension of each of the multiple bundles is equal to or greater than the radius of the core portion.

[0008] A second aspect of the present invention is a coaxial cable with a connector, comprising the coaxial cable of the first aspect and a connector connected to the coaxial cable, wherein the connector comprises a first terminal to which the tip of the core wire drawn out from between the plurality of bundles woven in a mesh pattern is connected, and a second terminal to which the tip of the shield is connected.

[0009] A third aspect of the present invention is a wire electric discharge machine comprising: a coaxial cable with connector of the second aspect; a wire electrode that is movable relative to a workpiece; and a discharge device connected to the connector and that applies a voltage to the wire electrode and the workpiece via the coaxial cable to generate an electric discharge between the workpiece and the wire electrode, wherein the discharge device is connected to one of the wire electrode and the workpiece via the core wire, and to the other of the wire electrode and the workpiece via the shield.

[0010] According to the aspects of the present invention, the spaces between the multiple bundles of the shield can be easily expanded, making it easier for the worker to pull out the core wire from the shield. [Brief explanation of the drawings]

[0011] [Figure 1] Fig. 1A is a schematic diagram of a coaxial cable according to an embodiment, and Fig. 1B is a diagram showing the shield of Fig. 1A with four bundles spread apart. [Figure 2] FIG. 2 is a schematic diagram of a connector-attached coaxial cable including the coaxial cable of FIG. 1A. [Figure 3] FIG. 3 is a schematic diagram of a wire electric discharge machine equipped with the connector-equipped coaxial cable of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Embodiment] FIG. 1A is a schematic diagram of a coaxial cable 10 according to an embodiment.

[0013] The coaxial cable 10 includes a core portion 12 and a braided shield (shield) 14 .

[0014] The core wire portion 12 is a linear member having a core wire 16 and an insulator 18. The core wire 16 is a conductive member (e.g., copper wire). The insulator 18 is a tubular insulating member (e.g., resin) that covers the core wire 16. Part of the insulator 18 in FIG. 1A is omitted in order to illustrate the core wire 16.

[0015] The shield 14 is a conductive member separate from the core 12. The shield 14 covers the insulator 18. Therefore, the shield 14 covers the core 12. Part of the shield 14 in FIG. 1A is omitted in order to illustrate the core 12. The coaxial cable 10 may further include a sheath. The sheath is an insulating member (e.g., resin) that covers the shield 14.

[0016] The shield 14 has a structure (braided structure) in which multiple bundles 20 are woven into a mesh. Each of the multiple bundles 20 is made of multiple aligned conductive wires (strands) 22. Each of the multiple strands 22 is, for example, a copper wire. The multiple strands 22 in each bundle 20 are arranged in parallel along the outer circumferential surface of the core portion 12. The direction in which the multiple strands 22 that make up a bundle 20 are aligned in parallel is defined as the width direction of the bundle 20. The width dimension WD in FIG. 1A indicates the length of the bundle 20 in the width direction.

[0017] 1A is made up of six wires 22. However, the number of wires 22 in each of the bundles 20 is not particularly limited as long as it does not contradict the description that will be given later.

[0018] A braided structure makes it easier to maintain the density of the multiple wires 22 than a structure in which the wires 22 are wound laterally around the circumferential direction of the core portion 12 (a horizontal winding structure). For example, a typical coaxial cable creates bent portions when bent. If the shield of the coaxial cable has a horizontal winding structure, the spacing between the multiple wires is likely to increase at the bent portion of the coaxial cable. In other words, the density of the multiple wires decreases at the bent portion. In contrast, the multiple wires 22 of the shield 14 are woven in a mesh pattern. Therefore, the spacing between the multiple wires 22 is less likely to increase even when the coaxial cable 10 is bent. In other words, the density of the multiple wires 22 is less likely to decrease.

[0019] Furthermore, the shield 14 is more likely to suppress electromagnetic noise leakage and impedance increases than a shield with a horizontal winding structure. For example, as described above, the density of the multiple wires in a shield with a horizontal winding structure is likely to decrease at bends. As a result, electromagnetic noise is more likely to leak at bends. Furthermore, when the density of the multiple wires decreases, the impedance of the shield (multiple wires) increases. In contrast, the density of the multiple wires 22 in the shield 14 is less likely to decrease. Therefore, the shield 14 is less likely to leak electromagnetic noise. Furthermore, an increase in the impedance of the shield 14 (multiple wires 22) is suppressed.

[0020] However, the core wire portion 12 (core wire 16) and the shield 14 are connected to different terminals, and therefore the core wire portion 12 (core wire 16) and the shield 14 are separated in advance before being connected to the respective terminals.

[0021] The core wire 16 and the shield 14 are separated by unraveling the braided structure of the shield 14. However, the shield 14 has a braided structure. Generally, unraveling the braid of thin wires (strands 22) is a time-consuming task. Therefore, simply adopting a braided structure as the structure of the shield 14 may prolong the worker's work time.

[0022] Therefore, each of the multiple bundles 20 in this embodiment has a width dimension WD equal to or greater than the radius RD of the core wire portion 12 (WD≧RD). This makes it easy to separate the core wire portion 12 and the shield 14 at the tip end of the coaxial cable 10 while preventing the impedance of the shield 14 from increasing. The reason for this is as follows.

[0023] FIG. 1B shows the shield 14 of FIG. 1A with the four bundles 20 (201-204) spread apart.

[0024] When an operator applies force, the wires 22 forming the same bundle 20 can be relatively easily displaced together along the width direction of the bundle 20. Here, if the width dimension WD of each of the multiple bundles 20 is equal to or greater than the radius RD of the core wire portion 12, the gap (pulling hole 24) between the four bundles 20 (201-204) can easily expand to a width equivalent to the diameter of the core wire portion 12.

[0025] In this case, the worker can easily pull out the core wire portion 12 from the pull-out hole 24. This separates the core wire portion 12 and the shield 14 at the tip end of the coaxial cable 10 (see FIG. 2).

[0026] Furthermore, the braided structure of the shield 14 remains unchanged except for the four bundles 20 that are moved to widen the drawing hole 24. Therefore, the density of the wires 22 does not decrease in areas other than the drawing hole 24. In other words, the impedance of the shield 14 is unlikely to increase.

[0027] FIG. 2 is a schematic diagram of a connectorized coaxial cable 26 that includes the coaxial cable 10 of FIG. 1A.

[0028] Use of the coaxial cable 10 makes it easy to manufacture the connectorized coaxial cable 26 shown in FIG.

[0029] The connectorized coaxial cable 26 includes a first connector (connector) 28 and a plurality of coaxial cables 10. The connectorized coaxial cable 26 of Fig. 2 includes four coaxial cables 10. However, the number of coaxial cables 10 is not particularly limited.

[0030] The first connector 28 is a coupling device that can be detachably attached to a corresponding second connector 56 (see FIG. 3). The first connector 28 includes a plurality of first terminals 30, a plurality of second terminals 32, and a first housing 34.

[0031] The number of first terminals 30 and second terminals 32 is the same as the number of coaxial cables 10. The first housing 34 is a housing that houses a plurality of first terminals 30 and a plurality of second terminals 32. In the first housing 34 of FIG. 2, the first terminals 30 and the second terminals 32 are arranged alternately. However, the arrangement order of the first terminals 30 and the second terminals 32 in the first housing 34 is not particularly limited.

[0032] Each of the plurality of coaxial cables 10 has a tip end 121 of the core wire portion 12 pulled out from the pull-out hole 24.

[0033] Each of the tip portions 121 of the core portions 12 includes a tip portion (core tip portion) 161 of the core wire 16. The core tip portions 161 are connected (crimped) to different first terminals 30. This allows the core wires 16 to be connected to the second connector 56 via the first terminals 30. Note that insulator 18 of tip portion 121 is removed in advance, if necessary, in order to crimp the core tip portions 161 to the first terminals 30.

[0034] The multiple shield tip portions 141 are connected (crimped) to different second terminals 32. This allows the multiple shields 14 to be connected to the second connector 56 via the multiple second terminals 32.

[0035] From the viewpoint of manufacturing costs, it is preferable to provide the first connector 28 at only one of the two longitudinal (cable length) end portions of the multiple coaxial cables 10. In other words, by intentionally not attaching a connector to the other end portion of the multiple coaxial cables 10, the manufacturing cost of the connectorized coaxial cable 26 can be kept low.

[0036] FIG. 3 is a schematic diagram of a wire electric discharge machine 36 equipped with the connector-equipped coaxial cable 26 of FIG.

[0037] The above-described coaxial cable with connector 26 is provided in, for example, a wire electric discharge machine 36. The wire electric discharge machine 36 is a machine tool that performs electric discharge machining on the workpiece W by generating an electric discharge between a wire electrode 40 and the workpiece W. The wire electric discharge machine 36 includes the coaxial cable with connector 26, a machining tank 38, the wire electrode 40, a table 42, an upper wire guide 44, a lower wire guide 46, and an electric discharge device 48.

[0038] The machining tank 38 is a tank that stores the machining fluid LQ. The machining fluid LQ is a dielectric liquid. The table 42, the upper wire guide 44, and the lower wire guide 46 are disposed in the machining tank 38.

[0039] The wire electrode 40 is a linear conductive member. The wire electrode 40 travels within the machining tank 38. The wire electrode 40 is suspended vertically within the machining tank 38. Note that a mechanism for running the wire electrode 40 while suspending it is known. Therefore, a description of this mechanism will be omitted.

[0040] The table 42 is a base that supports the workpiece W. The table 42 and the workpiece W are immersed in the machining liquid LQ in the machining tank 38. A jig for fixing the workpiece W may be installed on the table 42.

[0041] The table is electrically connected to the plurality of shields 14. As a result, the work-piece W and the plurality of shields 14 are electrically connected via the table .

[0042] The table 42 is connected to rear ends (shield rear ends) 142 of the multiple shields 14. The shield rear ends 142 are the front ends of the shields 14 on the opposite side from the shield front ends 141 that are crimped to the second terminals 32 (see FIG. 3).

[0043] The table 42 disposed within the machining tank 38 and the plurality of shields 14 disposed outside the machining tank 38 are connected via, for example, a known through-hole terminal block and a plurality of earth cables. In this case, the through-hole terminal block is attached to the machining tank 38. The through-hole terminal block penetrates the wall of the machining tank 38. A plurality of earth cables are disposed within the machining tank 38. The plurality of earth cables are connected to the table 42 and the through-hole terminal block. For example, the plurality of earth cables are screwed to the table 42 and the through-hole terminal block. This connects the table 42 and the through-hole terminal block within the machining tank 38. The plurality of earth cables are waterproofed in advance. The rear ends 142 of the plurality of shields are connected to the through-hole terminal block outside the machining tank 38 (machining liquid LQ). For example, the rear ends 142 of the plurality of shields are screwed to the through-hole terminal block. This connects the table 42 and the plurality of shields 14. The plurality of shields 14 are not immersed in the machining liquid LQ. The through terminal block and the plurality of earth cables are not shown.

[0044] The table 42 is also connected to a plurality of servo motors. These servo motors are controlled by a control device of the wire electric discharge machine 36. This control device is, for example, a computerized numerical controller (CNC). The control device controls the plurality of servo motors to move the table 42 in the horizontal direction. The plurality of servo motors and the control device are not shown in the figure.

[0045] As the table 42 moves in the horizontal direction, the workpiece W moves integrally with the table 42 within the processing tank 38. As a result, the relative positional relationship between the workpiece W and the wire electrode 40 within the processing tank 38 changes in the horizontal direction. In other words, the workpiece W and the wire electrode 40 move relative to each other in the horizontal direction.

[0046] 3 does not penetrate the workpiece W. However, actual electric discharge machining may start with the wire electrode 40 having penetrated the workpiece W.

[0047] The upper wire guide 44 is a guide member that is arranged vertically above the workpiece W. The wire electrode 40 is supplied into the machining tank 38 through the upper wire guide 44. The upper wire guide 44 guides the wire electrode 40 toward the workpiece W.

[0048] The upper wire guide 44 includes an electrode pin 50. The electrode pin 50 is electrically connected to the core wire rear end portions 162 of the multiple core wires 16. The core wire rear end portions 162 are the tip ends of the core wires 16 on the opposite side to the core wire tip portions 161 crimped to the first terminals 30 (see FIG. 3).

[0049] The core wire rear end portion 162 can be easily pulled out from the shield 14 through the pull-out hole 24 (242). The pull-out hole 242 is a pull-out hole 24 different from the pull-out hole 24 (241) through which the core wire front end portion 161 is pulled out (see FIG. 3). The pull-out hole 242 easily expands in the same manner as the pull-out hole 241.

[0050] The electrode pin 50 disposed within the machining tank 38 and the multiple core wire rear ends 162 disposed outside the machining tank 38 are connected via, for example, the aforementioned through-hole terminal block, a metal block, and multiple hot cables. In this case, the metal block contacts the electrode pin 50. The multiple hot cables are disposed within the machining tank 38. The multiple hot cables are connected to the metal block and the through-hole terminal block. For example, the multiple hot cables are screwed to the metal block and the through-hole terminal block. This connects the through-hole terminal block and the electrode pin 50. The multiple hot cables are waterproofed in advance. The multiple core wire rear ends 162 are connected to the through-hole terminal block outside the machining tank 38 (machining liquid LQ). For example, the multiple core wire rear ends 162 are screwed to the through-hole terminal block. This connects the electrode pin 50 and the multiple core wire rear ends 162. The multiple core wire rear ends 162 (core wires 16) are not immersed in the machining liquid LQ. The metal block and the hot cables are not shown in the figure. The feed-through terminal block that connects the rear ends 162 of the core wires to the electrode pins 50 may be a terminal block separate from the feed-through terminal block that connects the shields 14 to the table 42.

[0051] Furthermore, the electrode pin 50 comes into contact with the wire electrode 40. This establishes electrical continuity between the wire electrode 40 and the core wires 16.

[0052] The lower wire guide 46 is a guide member that is positioned vertically below the workpiece W. After passing through the workpiece W, the wire electrode 40 is discarded outside the machining tank 38 through the lower wire guide 46. The discarded wire electrode 40 is collected in a collection box (not shown).

[0053] The discharge device 48 is a device that applies a voltage pulse (voltage) to the wire electrode 40 and the workpiece W. The discharge device 48 includes a DC power supply (power supply) 52, a switching element 54, and a second connector 56.

[0054] The power supply 52 has a negative terminal 521 and a positive terminal 522. The negative terminal 521 is connected to the switching element .

[0055] The second connector 56 includes a plurality of third terminals 58, a plurality of fourth terminals 60, and a second housing 62. The second housing 62 is a housing that accommodates the plurality of third terminals 58 and the plurality of fourth terminals 60.

[0056] The third terminals 58 are connected in parallel to one another. The parallel-connected third terminals 58 are connected to the switching element 54. As a result, the third terminals 58 are connected to the negative terminal 521 via the switching element 54.

[0057] Furthermore, when the second connector 56 and the first connector 28 are coupled, the multiple third terminals 58 are connected to different first terminals 30. Therefore, each of the multiple first terminals 30 is connected to the negative terminal 521 via the switching element 54. As a result, the negative terminal 521 and the electrode pin 50 are electrically connected to each other.

[0058] The plurality of fourth terminals 60 are connected in parallel to one another. The plurality of fourth terminals 60 connected in parallel are connected to the plus terminal 522.

[0059] Furthermore, when the second connector 56 and the first connector 28 are coupled together, the multiple fourth terminals 60 are connected to different second terminals 32. Therefore, each of the multiple second terminals 32 is connected to the positive terminal 522. As a result, the positive terminal 522 and the work-piece W are electrically connected to each other.

[0060] The discharge device 48 applies a voltage to the wire electrode 40 and the workpiece W via the connector-equipped coaxial cable 26. This generates a discharge between the wire electrode 40 and the workpiece W. The above-mentioned control device (CNC) may also control the discharge device 48. This completes the description of the exemplary configuration of the wire electric discharge machine 36.

[0061] As described above, the shield 14 can suppress an increase in impedance, and therefore the coaxial cable 10 of this embodiment can cause the machining current to rise more quickly than a typical coaxial cable.

[0062] As a result, the amount of workpiece W removed per unit time in response to the discharge increases, which is expected to improve the machining speed. Also, by suppressing the increase in impedance of the shield 14, a larger machining current can be passed through fewer coaxial cables 10 than in conventional coaxial cables.

[0063] Moreover, the multiple coaxial cables 10 can be connected together to the discharge device 48 via the first connector 28. In this regard, the seller of the wire electric discharge machine 36 may transport the discharge device 48 and the equipment of the wire electric discharge machine 36 other than the discharge device 48 (for example, the machining tank 38) separately to the delivery destination. In this case, the work of connecting each of the electrode pins 50 and the table 42 to the discharge device 48 is performed at the delivery destination.

[0064] Here, the discharge device 48 and the multiple coaxial cables 10 can be easily connected by coupling the first connector 28 and the second connector 56. This allows the wire electric discharge machine 36 to be quickly installed at the delivery destination.

[0065] [Variations] Modifications of the above embodiment are described below. However, descriptions that overlap with the above embodiment will be omitted as much as possible in the following description. Components that have already been described in the above embodiment will be assigned the same reference numerals as in the above embodiment unless otherwise specified.

[0066] (Variation 1) The number of coaxial cables 10 included in the connectorized coaxial cable 26 may be one. In this case, the number of each of the first terminals 30 and second terminals 32 may be one.

[0067] However, even in this case, the second connector 56 may include a plurality of third terminals 58 and a plurality of fourth terminals 60. In other words, the number of each of the third terminals 58 and the fourth terminals 60 may be greater than the number of each of the coaxial cables 10, the first terminals 30, and the second terminals 32.

[0068] The operator of the wire electric discharge machine 36 may replace a plurality of connectorized coaxial cables 26 each having a different number of coaxial cables 10 with the second connector 56 as appropriate.

[0069] (Variation 2) The electrode pin 50 may be provided on the lower wire guide 46. In this case as well, the wire electrode 40 and the multiple core wires 16 are electrically connected via the electrode pin 50.

[0070] Both the upper wire guide 44 and the lower wire guide 46 may be provided with electrode pins 50. In this case, the multiple core wires 16 include multiple core wires 16 connected to the electrode pins 50 of the upper wire guide 44 and multiple core wires 16 connected to the electrode pins 50 of the lower wire guide 46.

[0071] (Variation 3) The connectorized coaxial cable 26 may further include a connector (third connector) for connecting the multiple core wire rear ends 162 and the multiple shield rear ends 142. In this case, a connector (fourth connector) connectable to the third connector may be installed in the processing tank 38. The third connector may be the same type of connector as the first connector 28.

[0072] According to this modification, the coaxial cable 10 can be easily attached to and detached from the electrode pin 50 and the work-piece W. That is, the multiple core wire rear ends 162 are connected to the electrode pin 50 via the fourth connector. Also, the multiple shield rear ends 142 are connected to the work-piece W via the fourth connector.

[0073] The present invention is not limited to the above-described embodiment and modifications, and various configurations can be adopted without departing from the gist of the present invention.

[0074] [Inventions Obtained from the Embodiments] The invention that can be understood from the above-described embodiment and modifications will be described below.

[0075] <First invention> The first invention is a coaxial cable (10) comprising a linear core portion (12) having a core wire (16) and a tubular insulator (18) covering the core wire, and a shield (14) covering the core wire portion, wherein the shield has a braided structure in which a plurality of bundles (20) of arranged wires (22) are braided in a mesh-like pattern, and the width dimension (WD) of each of the plurality of bundles is equal to or greater than the radius (RD) of the core wire portion.

[0076] This allows the spacing between the multiple bundles of the shield to easily expand to a diameter equivalent to the core wire portion, making it easier to pull out the core wire from the shield.

[0077] <Second Invention> The second invention is a coaxial cable with connector (26) comprising the coaxial cable (10) of the first invention and a connector (28) connected to the coaxial cable, wherein the connector comprises a first terminal (30) to which the tip end (161) of the core wire drawn out from between the plurality of bundles woven in a mesh pattern is connected, and a second terminal (32) to which the tip end (141) of the shield is connected.

[0078] This allows the coaxial cable to be easily connected to other devices (electrical circuits) via the connector. The tip of the core wire and the tip of the shield can also be easily separated. Therefore, coaxial cables with connectors are easy to manufacture.

[0079] The coaxial cable with connector may include a plurality of the coaxial cables, and the connector may include a plurality of the first terminals and a plurality of the second terminals, thereby enabling the plurality of coaxial cables to be connected to another device (e.g., a discharge device) all at once.

[0080] <Third invention> The third invention is a wire electric discharge machine (36) comprising the connector-equipped coaxial cable (26) of the second invention, a wire electrode (40) movable relative to a workpiece (W), and an electric discharge device (48) connected to the connector and applying a voltage to the wire electrode and the workpiece via the coaxial cable to generate an electric discharge between the workpiece and the wire electrode, wherein the electric discharge device is connected to one of the wire electrode and the workpiece via the core wire and to the other of the wire electrode and the workpiece via the shield.

[0081] This allows the discharge device and the coaxial cable to be easily connected via the connector. [Explanation of symbols]

[0082] 10...Coaxial cable 12...Core 14...Shield 16...Core 18...Insulator 20...Bundle 22...Bare wire 26...Coaxial cable with connector 28...First connector (connector) 30...First terminal 32... Second terminal 36... Wire electric discharge machine 40...wire electrode 48...discharge device 141...Tip of shield 161...Tip of core wire RD: Radius of core wire W: Workpiece WD: Width of bundle

Claims

1. A coaxial cable with a connector, the coaxial cable having a first connector provided at a first end, which is one end of the coaxial cable; a wire electrode that is movable relative to the workpiece; a discharge device including a second connector connected to the first connector, and applying a voltage to the wire electrode and the workpiece via the connector-equipped coaxial cable to generate a discharge between the workpiece and the wire electrode; Equipped with The coaxial cable is a linear core portion having a core and a cylindrical insulator covering the core; a shield covering the core wire portion; Equipped with The shield has a braided structure in which a plurality of bundles of wires are braided in a mesh pattern, a width dimension of each of the plurality of bundles is equal to or greater than the radius of the core wire portion; The first connector is a first terminal to which a tip end of the core wire drawn out from between the plurality of bundles woven in a mesh pattern at the first end portion is connected; a second terminal of the first end to which a tip end of the shield is connected; A wire electric discharge machine comprising:

2. A wire electric discharge machine according to claim 1, At a second end of the coaxial cable opposite to the first end, the core wire is directly fixed to a terminal block, and is thereby electrically connected to the wire electrode via the terminal block; At the second end, the shield is directly fixed to the terminal block, thereby being electrically connected to the workpiece via the terminal block.

3. 3. The wire electric discharge machine according to claim 1, A plurality of the coaxial cables are provided, The first connector includes a plurality of the first terminals and a plurality of the second terminals.

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