Control device and estimation method for wire electrical discharge machine

Abstract

The present invention provides a control device (16) and an estimation method for a wire electrical discharge machine (10), which estimate the tension of a wire electrode (12) based on information obtained from a motor (38) included in a feeding mechanism (22) of the wire electrode (12). In a control device (16) of a wire electric discharge machine (10), the wire electric discharge machine (10) includes a first motor (38A) and a second motor (38B) for rotating a first roller (32A) and a second roller (32B) for conveying a wire electrode (12), and the control device (16) of the wire electric discharge machine includes: an acquisition unit (58) for acquiring at least one of an interference load and a torque command of one of the first motor (38A) and the second motor (38B); a feed motor control unit (64) for controlling the first motor (38A) and the second motor (38B) to tension the wire electrode (12); and an estimation unit (60) for estimating tension based on at least one of the interference load and the torque command when the wire electrode (12) is tensioned.

Description

Technical Field

[0001] The present invention relates to a control device and an estimation method for a wire electrical discharge machining machine. In particular, it relates to a control device and an estimation method for a wire electrical discharge machining machine that estimates the tension of a wire electrode of the wire electrical discharge machining machine. Background Art

[0002] A wire electrical discharge machining machine generally includes a tension sensor that detects the tension of a wire electrode. As an example of a tension sensor, for example, a "wire electrode tension sensor" is disclosed in Japanese Patent Application Laid-Open No. 2002-340711. Summary of the Invention

[0003] A general wire electrical discharge machining machine detects the tension of a wire electrode through a tension sensor. Here, it is assumed that if the tension of the wire electrode can be estimated without a tension sensor, it is considered that the tension sensor can be omitted from the structure of the wire electrical discharge machining machine. In addition, if the tension sensor can be omitted from the structure of the wire electrical discharge machining machine, it is considered to be advantageous in terms of simplifying the mechanical structure of the wire electrical discharge machining machine and reducing the cost of components.

[0004] Therefore, an object of the present invention is to provide a control device and an estimation method for a wire electrical discharge machining machine that estimate the tension of a wire electrode based on information obtained from a motor included in a feeding mechanism of the wire electrode.

[0005] One aspect of the present invention is a control device for a wire electrical discharge machining machine, the wire electrical discharge machining machine including: a spool around which a wire electrode is wound; a first roller that conveys the wire electrode wound around the spool to a workpiece to be machined by rotation; a second roller that conveys the wire electrode that has passed through the workpiece to a recovery box by rotation; a first motor that rotates the first roller; and a second motor that rotates the second roller, wherein the control device for the wire electrical discharge machining machine includes: an acquisition unit that acquires at least one of disturbance load based on a drive current of one of the first motor and the second motor selected, i.e., the selected motor, and a torque command for rotating at a predetermined command speed; a feed motor control unit that controls the first motor and the second motor so that the wire electrode is tensioned between the first roller and the second roller; and an estimation unit that estimates the tension of the tensioned wire electrode based on at least one of the disturbance load and the torque command acquired by the acquisition unit when the wire electrode is tensioned between the first roller and the second roller.

[0006] Another aspect of the present invention is a method for estimating a wire electrical discharge machining machine, which includes: a spool that winds a wire electrode; a first roller that conveys the wire electrode wound around the spool to a workpiece by rotation; a second roller that conveys the wire electrode that has passed through the workpiece to a recovery box by rotation; a first motor that rotates the first roller; and a second motor that rotates the second roller. The estimation method estimates the tension of the wire electrode tensioned between the first roller and the second roller. The estimation method includes: a feed motor control step of controlling the first motor and the second motor to tension the wire electrode between the first roller and the second roller, and obtaining at least one of the disturbance load based on the drive current and the torque command for rotating at a predetermined command speed for the selected one of the first motor and the second motor; and an estimation step of estimating the tension based on at least one of the disturbance load and the torque command when the wire electrode is tensioned between the first roller and the second roller.

[0007] According to an aspect of the present invention, there is provided a control device and an estimation method for a wire electrical discharge machining machine, which estimate the tension of a wire electrode based on information obtained from a motor included in a feed mechanism of the wire electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is an overall structure diagram of the wire electrical discharge machining machine of the embodiment.

[0009] Figure 2 It is a simplified structure diagram of a wire electrode feed mechanism included in the wire electrical discharge machining machine of the embodiment.

[0010] Figure 3 It is a simplified structure diagram of a control device of the wire electrical discharge machining machine of the embodiment.

[0011] Figure 4 It is a simplified structure diagram of a spool around which a wire electrode is wound.

[0012] Figure 5 It is a flowchart showing the process of the estimation method of the embodiment.

[0013] Figure 6 It is a chart illustrating the correlation between the disturbance load of the first motor and the torque generated by the torque generating mechanism.

[0014] Figure 7 It is a simplified structure diagram of the control device of Modification 2.

[0015] Figure 8 It is a simplified structure diagram of the control device of Modification 6. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, preferred embodiments will be given, and the control device and estimation method of the wire electrical discharge machining apparatus of the present invention will be described in detail with reference to the accompanying drawings. However, descriptions of known matters may sometimes be omitted.

[0017] [Embodiment]

[0018] Figure 1 It is an overall structural diagram of the wire electrical discharge machining apparatus 10 of the embodiment. Figure 1 In this figure, the X direction, Y direction, and Z direction indicated by the arrows are mutually orthogonal directions.

[0019] The wire electrical discharge machining apparatus 10 is a machine tool that performs electrical discharge machining on the workpiece 25 by generating a discharge between the wire electrode 12 and the workpiece 25 (between the electrodes).

[0020] The wire electrical discharge machining apparatus 10 of the present embodiment includes a machining apparatus main body 14 and a control device 16. The machining apparatus main body 14 is a machine that performs electrical discharge machining with the wire electrode 12. The control device 16 is a device that controls the machining apparatus main body 14, which is generally also called a numerical control device. In the present embodiment, it is a device that particularly estimates the tension of the wire electrode 12.

[0021] Among them, the machining apparatus main body 14 includes a machining tank 18, a support table 20, a feed mechanism 22, and a recovery box 24. The machining tank 18 is a tank that stores machining fluid. The machining fluid is a dielectric liquid, such as deionized water. The support table 20 is a pedestal that is immersed in the machining fluid by being disposed in the machining tank 18 and has a surface that extends in the X direction and the Y direction. The support table 20 supports the workpiece 25 in the machining fluid through this surface.

[0022] Regarding the support table 20, the wire electrical discharge machining apparatus 10 may further include a support table moving mechanism that moves the support table 20 in the X direction, Y direction, and Z direction. The support table moving mechanism is not described in detail in the present embodiment, but it is configured to include, for example, a plurality of servo motors.

[0023] The feed mechanism 22 is a mechanism that conveys the wire electrode 12 along the feeding direction so that the wire electrode 12 passes through the workpiece 25 supported by the support table 20. In addition, the recovery box 24 houses the wire electrode 12 that has passed through the workpiece 25. In addition, the so-called "feeding direction" is the direction toward the first roller 32A when viewed from the spool 30 described later, the direction toward the second roller 32B when viewed from the first roller 32A, and the direction toward the recovery box 24 when viewed from the second roller 32B.

[0024] Figure 2 It is a simplified structural diagram of the feed mechanism 22 of the wire electrode 12 included in the wire electrical discharge machining apparatus 10 of the embodiment.

[0025] The feed mechanism 22 will be further described. The feed mechanism 22 includes: a supply system 26 that conveys the wire electrode 12 toward the workpiece 25; and a recovery system 28 that conveys the wire electrode 12 that has passed through the workpiece 25 toward the recovery box 24.

[0026] The supply system 26 includes a spool 30, a first roller 32A, a first die guide 34A, a torque generation mechanism 35, and a first motor 38A. The spool 30 is a rotatable cylinder around which the wire electrode 12 is wound in a drawable manner. The first roller 32A is a rotatable roller over which the wire electrode 12 drawn from the spool 30 is strung. The first die guide 34A is a die guide that guides the wire electrode 12 from the first roller 32A toward the workpiece 25 and is disposed in the machining groove 18. The first motor 38A is a motor that rotates the first roller 32A integrally with its rotation axis, and is, for example, a servo motor connected to the first roller 32A.

[0027] The torque generation mechanism 35 is a mechanism that generates a torque called "reverse torque" in a predetermined magnitude in the present embodiment and applies this torque to the spool 30. Here, the reverse torque is a torque in a direction opposite to the rotation direction of conveying the wire electrode 12 along the feeding direction. The torque generation mechanism 35 of the present embodiment has a torque motor 36, and the above-mentioned reverse torque is applied to the spool 30 in a predetermined magnitude by this torque motor 36. In addition, the structure of the torque generation mechanism 35 only needs to be a structure capable of generating a reverse torque in a predetermined magnitude, and is not limited to the structure having the torque motor 36.

[0028] An encoder (not shown) is provided in the first motor 38A. Thus, for the first motor 38A, the rotational speed of the rotation axis can be detected. In addition, hereinafter, the "rotation of the rotation axis of the first motor 38A" will also be simply referred to as the "rotation of the first motor 38A".

[0029] The above is the structure of the supply system 26. In addition, as Figure 2 shown, the supply system 26 may further include an auxiliary roller 40 as a roller that strings the wire electrode 12 between the spool 30 and the first roller 32A. The number of the auxiliary rollers 40 included in the supply system 26 may be one or more. In addition, the supply system 26 may include a first die guide moving mechanism (not shown) that moves the first die guide 34A in a direction parallel to the X-Y plane of Figure 1 . The detailed description of the first die guide moving mechanism is omitted in the present embodiment, but it is configured to include a servo motor, for example.

[0030] Next, the structure of the recovery system 28 of the feed mechanism 22 will be described. The recovery system 28 includes a second die guide 34B, a second roller 32B, a third roller 42, and a second motor 38B. The second die guide 34B is a die guide that guides the wire electrode 12 that has passed through the workpiece 25 and is disposed in the machining tank 18. In addition, the second roller 32B and the third roller 42 are rotatable rollers that clamp the wire electrode 12 that has passed through the second die guide 34B. Among them, the third roller 42 is a roller generally referred to as a pinch roller and is configured to be separable from or contact the second roller 32B for clamping and releasing. The second motor 38B is a servo motor in the present embodiment. The rotating shaft of the second motor 38B is connected to the second roller 32B. Thus, when a drive current is supplied to the second motor 38B, the rotating shaft of the second motor 38B rotates integrally with the second roller 32B.

[0031] Similar to the first motor 38A, an encoder is provided in the second motor 38B. The rotation speed of the rotating shaft of the second motor 38B is detected by the encoder provided in the second motor 38B. In addition, hereinafter, similar to the first motor 38A and the torque motor 36, the "rotation of the rotating shaft of the second motor 38B" is also simply referred to as "the rotation of the second motor 38B".

[0032] The above is the structure of the recovery system 28. In addition, the recovery system 28 may also include one or more auxiliary rollers 40 similar to the supply system 26. The auxiliary roller 40 included in the recovery system 28 is, for example, disposed between the second die guide 34B and the second roller 32B (the third roller 42), and the wire electrode 12 is spanned. In addition, the recovery system 28 may include a second die guide moving mechanism (not shown) that moves the second die guide 34B in a direction parallel to the X-Y plane of Figure 1 . The second die guide moving mechanism is similar to the above-described first die guide moving mechanism and is configured to include, for example, a servo motor.

[0033] Figure 3 is a simplified structural diagram of the control device 16 of the wire electrical discharge machine 10 of the present embodiment.

[0034] Next, the structure of the control device 16 of the wire electrical discharge machining machine 10 will be described. The control device 16 includes a storage unit 44, a display unit 46, an operation unit 48, an amplifier 50, and an arithmetic unit 52. The storage unit 44 stores information, which is composed of hardware such as a RAM (Random Access Memory) and a ROM (Read Only Memory), for example. A predetermined program 54 for controlling the feed mechanism 22 is pre-stored in the storage unit 44 in the present embodiment. The display unit 46 displays information, which is a display device having a liquid crystal screen, for example. The operation unit 48 is a component operated by an operator to input information (instructions) to the control device 16, and is composed of a keyboard, a mouse, or a touch panel installed on the screen (liquid crystal screen) of the display unit 46, for example.

[0035] The amplifier 50 is a servo amplifier in the present embodiment, and includes a first amplifier 50A, a second amplifier 50B, and a third amplifier 50C. Among them, the first amplifier 50A and the second amplifier 50B perform feedback control on the first motor 38A and the second motor 38B based on instructions issued from the arithmetic unit 52 described in detail later. In addition, the third amplifier 50C performs feedback control on the torque motor 36 based on an instruction output from the arithmetic unit 52.

[0036] The arithmetic unit 52 processes information through arithmetic operations, and is composed of hardware such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit), for example. The arithmetic unit 52 includes a motor control unit 56, an acquisition unit 58, an estimation unit 60, and a calculation unit 62. These units are realized by the arithmetic unit 52 executing a predetermined program 54.

[0037] Hereinafter, each unit included in the arithmetic unit 52 will be described in sequence. In addition, hereinafter, when the first motor 38A and the second motor 38B are not particularly distinguished and described, both are referred to and only recorded as "feed motor 38". Similarly, when the first roller 32A and the second roller 32B are not particularly distinguished and described, both are referred to and only recorded as "feed roller 32".

[0038] The motor control unit 56 controls the feed motor 38 and the torque motor 36 via the amplifier 50, and includes a feed motor control unit 64 and a torque motor control unit (torque generation mechanism control unit) 66 described below.

[0039] The feed motor control unit 64 controls the feed motor 38 among the feed motor 38 and the torque motor 36. The feed motor control unit 64 issues commands to the first amplifier 50A and the second amplifier 50B in order to rotate the feed motor 38 at a predetermined rotational speed. Hereinafter, the rotational speed represented by this command is also referred to as the "command speed".

[0040] The feed motor control unit 64 indicates the command speed (first command speed) of the first motor 38A to the first amplifier 50A, and indicates the command speed (second command speed) of the second motor 38B to the second amplifier 50B. Among the first command speed and the second command speed, the second command speed is the high speed. Therefore, when the two feed motors 38 rotate at the command speeds respectively, the wire electrode 12 is pulled from the first roller 32A to the second roller 32B and the third roller 42, and is tensioned between the first roller 32A and the second roller 32B.

[0041] However, when the wire electrode 12 is installed between the first roller 32A and the second roller 32B, the rotational speed of the first motor 38A may exceed the first command speed along with the rotational speed of the second motor 38B. In addition, the rotational speed of the second motor 38B may be less than the second command speed along with the rotational speed of the first motor 38A. Therefore, the feed motor control unit 64 issues commands to the first amplifier 50A and the second amplifier 50B indicating the torque generated by the first motor 38A and the second motor 38B. Hereinafter, this command or the torque represented by this command is also referred to as the "torque command".

[0042] The feed motor control unit 64 issues a torque command indicating a torque (reverse torque) in the direction opposite to the rotational direction for feeding the wire electrode 12 along the feeding direction to the first amplifier 50A. Thereby, the first amplifier 50A can cause the first motor 38A to generate the commanded reverse torque and decelerate the rotational speed of the first motor 38A to the first command speed. In addition, the feed motor control unit 64 issues a torque command indicating a torque (hereinafter, also referred to as "forward torque" for convenience) in the rotational direction for feeding the wire electrode 12 along the feeding direction to the second amplifier 50B. Thereby, the second amplifier 50B can cause the second motor 38B to generate the commanded forward torque and increase the rotational speed of the second motor 38B to the second command speed.

[0043] The torque motor control unit 66 issues a torque command indicating a reverse torque of a predetermined magnitude to the third amplifier 50C. The predetermined magnitude can be specified and changed by other units provided in the arithmetic unit 52 or by an operator operating the operation unit 48. Hereinafter, the "reverse torque of a predetermined magnitude" will also be simply referred to as the "predetermined reverse torque". According to the torque command issued from the torque motor control unit 66, the third amplifier 50C causes the torque motor 36 to generate a predetermined reverse torque, and it is possible to prevent the wire electrode 12 from being excessively fed out from the bobbin 30 as the feed motor 38 rotates.

[0044] Next, the acquisition unit 58 will be described. In the present embodiment, the acquisition unit 58 acquires the disturbance load based on the drive current of the selected motor 38' which is one of the two feed motors 38 from the amplifier 50. The selected motor 38' can be selected by the manufacturer of the wire electrical discharge machining machine 10 before the factory shipment stage, or can be appropriately selected by the operator when using the wire electrical discharge machining machine 10.

[0045] In addition, the disturbance load refers to the difference between the drive current when the selected motor 38' rotates at the commanded speed without being affected by the disturbance and the drive current when the selected motor 38' rotates at the commanded speed under the influence of the disturbance.

[0046] For example, assume that the rotational speed of the first motor 38A deviates from the first commanded speed due to the disturbance. As the disturbance here, there are the force exerted on the first motor 38A due to the reverse torque of the torque motor 36, the tension of the wire electrode 12, and the frictional force applied to the wire electrode 12 by the third roller 42. In this case, as described above, the first amplifier 50A adjusts the drive current based on the torque command. The disturbance load of the first motor 38A is obtained based on the adjusted drive current.

[0047] In addition, for example, assume that the rotational speed of the second motor 38B deviates from the second commanded speed due to the disturbance. As the disturbance here, there are the force exerted on the second motor 38B due to the reverse torque of the torque motor 36, the tension of the wire electrode 12, and the frictional force applied to the wire electrode 12 by the third roller 42. In this case, as described above, the second amplifier 50B adjusts the drive current based on the torque command. The disturbance load of the second motor 38B is obtained based on the adjusted drive current.

[0048] The estimation unit 60 estimates the tension of the wire electrode 12 based on the disturbance load acquired by the acquisition unit 58 when the wire electrode 12 is tensioned. More specifically, the estimation unit 60 of the present embodiment estimates the tension based on the difference D1 between the disturbance load when the wire electrode 12 is conveyed and tensioned between the two feed rollers 32 and a predetermined load determined in advance.

[0049] The predetermined load is the interference load of the motor 38' selected when the tension of the wire electrode 12 between the two feed rollers 32 is zero. This can be achieved, for example, when the wire electrode 12 is deflected between the first roller 32A and the second roller 32B by controlling the rotational speed of the feed motor 38. In addition, the predetermined load is not limited to the case where the wire electrode 12 is deflected. It can also be achieved when the wire electrode 12 that is tensioned and conveyed between the first roller 32A and the second roller 32B breaks. In addition, it can also be achieved when the clamping of the wire electrode 12 by the second roller 32B and the third roller 42 is released.

[0050] That is, the predetermined load represents the magnitude of the interference load generated by interference other than the tension of the wire electrode 12 among the interferences received by the selected motor 38'. Moreover, the difference D1 obtained by taking this interference load as the predetermined interference load represents the magnitude of the interference load generated only by the tension of the wire electrode 12. Therefore, by calculating the difference D1, the estimation unit 60 can easily and highly accurately estimate the magnitude of the tension of the wire electrode 12.

[0051] Figure 4 It is a simplified structural diagram of the spool 30 around which the wire electrode 12 is wound. In addition, Figure 2 is from Figure 4 the viewing point observed from the left side in the figure.

[0052] Next, the calculation unit 62 will be described. The calculation unit 62 calculates the radius R2 of the spool 30 around which the wound wire electrode 12 is located based on the feed amount of the wire electrode 12. More specifically, the calculation unit 62 of the present embodiment calculates sequentially by the following formula (1). In addition, hereinafter, R1 is the initial value of the radius R2, is the wire diameter of the wire electrode 12, W is the wire length (the above-mentioned feed amount) of the wire electrode 12 that has been conveyed from the spool 30. In addition, a is the porosity of the wire electrode 12 wound around the spool 30, which is the volume ratio of the gap to the total volume of the wire electrode 12 including the gaps between the wires and between the wire electrode 12 and the spool 30. L is the width orthogonal to the radial direction of the spool 30. Among them, R1, a, and L are known values, and the operator can specify them in advance via the operation unit 48. Regarding R1, it can also be obtained by substituting the predetermined load (F M ) obtained by setting the tension of the wire electrode 12 to zero and the reverse torque (T 35 ) at this time into formula (2) described later. In addition, W can be calculated not only indirectly according to the rotational speed of the spool 30, but also according to the rotational speed of the first motor 38A and the diameter of the first roller 32A, or according to the rotational speed of the second motor 38B and the diameter of the second roller 32B. In short, formula (1) indicates that as the wire electrode 12 is fed out, the radius R2 of the spool 30 gradually becomes smaller.

[0053] [Mathematical formula 1]

[0054]

[0055] The radius R2 of the spool 30 obtained by this formula (1) is between the reverse torque (T 35 ) of the torque generating mechanism 35 and the disturbance load (F M ) generated by disturbances other than the tension of the wire electrode 12, and has a relationship expressed by the following formula (2).

[0056] [Mathematical formula 2]

[0057] F M = T 35 / R2…(2)

[0058] Formula (2) indicates that if the magnitude of the reverse torque of the torque generating mechanism 35 is assumed to be fixed, the magnitude of the disturbance load generated by disturbances other than the tension changes according to the change in the radius R2, and may deviate from the predetermined load. Therefore, in the present embodiment, based on formula (2), the magnitude of the reverse torque of the torque generating mechanism 35 is adjusted so that the disturbance load generated by disturbances other than the tension is consistent with the predetermined load regardless of the radius R2 of the spool 30. In the present embodiment, by controlling the torque motor 36 of the torque generating mechanism 35, the magnitude of the reverse torque can be easily and highly accurately adjusted.

[0059] Specifically, in the present embodiment, the calculation unit 62 calculates the radius R2 of the spool 30 based on formula (1), and further calculates the magnitude of the reverse torque corresponding to the radius R2 and the predetermined load based on formula (2). In addition, the calculation unit 62 sequentially notifies the calculated reverse torque to the torque motor control unit 66. The torque motor control unit 66 controls the torque motor 36 of the torque generating mechanism 35 based on the notified reverse torque. Thereby, it is possible to suppress the deviation between the predetermined load used in the estimation by the estimation unit 60 and the disturbance load generated by disturbances other than the tension.

[0060] The above is an example of the structure of the control device 16 of the present embodiment. Next, a method for estimating the tension of the wire electrode 12 executed by the above control device 16 will be described.

[0061] Figure 5 is a flowchart showing the process of the estimation method of the present embodiment.

[0062] In the estimation method of the present embodiment, as Figure 5As shown, first, a feed motor control step is performed. The feed motor control step is a step of controlling the first motor 38A and the second motor 38B so that the wire electrode 12 is tensioned between the first roller 32A and the second roller 32B, and obtaining the disturbance load based on the drive current of the selected motor 38'. This step can be executed by the cooperation of the feed motor control unit 64 and the obtaining unit 58.

[0063] In addition, in the estimation method of the embodiment, a calculation step and a torque motor control step (torque generation mechanism control step) are also performed. Among them, the calculation step is a step of sequentially calculating the radius R2 of the spool 30 and the magnitude of the reverse torque of the torque generation mechanism 35 corresponding to the radius R2 based on the feed amount W of the wire electrode 12. This step is executed by the calculation unit 62.

[0064] The torque motor control step (torque generation mechanism control step) is a step of sequentially adjusting the reverse torque of the torque motor 36 (torque generation mechanism 35) based on the calculation results in the calculation step. By notifying the calculation results obtained by the calculation unit 62 in the calculation step to the torque motor control unit 66, this step is executed by the torque motor control unit 66. Through this step, the magnitude of the disturbance load generated by disturbances other than the tension in the disturbance load of the first motor 38A is sequentially adjusted to be a predetermined load.

[0065] The estimation step is a step of estimating the tension of the wire electrode 12 based on the obtained disturbance load. This step is executed by the estimation unit 60. As described above, the estimation unit 60 of the present embodiment estimates the tension based on the difference D1 between the disturbance load and the predetermined load.

[0066] By executing the above estimation method, the control device 16 can easily estimate the tension of the wire electrode 12. In addition, when the estimated tension deviates from the allowable range with respect to the tension required for performing accurate electric discharge machining, it can also be determined that an abnormality has occurred in the tensioning of the wire electrode 12.

[0067] In this way, according to the present embodiment, there is provided a control device 16 and an estimation method for a wire electric discharge machining machine 10 that estimate the tension of the wire electrode 12 based on information obtained from the feed motor 38 included in the feed mechanism 22 of the wire electrode 12.

[0068] According to the control device 16 of the present embodiment, it is not necessary to provide a wire electrode 12 tension sensor for the wire electric discharge machining machine 10. Therefore, according to the control device 16 of the present embodiment, in terms of simplifying, miniaturizing the mechanical structure of the wire electric discharge machining machine 10 and reducing the cost of components, it is possible to omit the tension sensor from the structure and be correspondingly advantageous.

[0069] [Modification Example]

[0070] As described above, an embodiment has been described as an example of the present invention. Various changes or improvements can be made to the above embodiment. In addition, as can be seen from the description of the scope of claims, the embodiments to which such changes or improvements are made can be included within the technical scope of the present invention.

[0071] (Modification Example 1)

[0072] In the control device 16 and the estimation method described in the embodiment, the tension is estimated based on the disturbance load of the feed motor 38. However, it is not limited thereto, and the control device 16 and the estimation method may also estimate the tension of the wire electrode 12 based on the torque command instead of the disturbance load.

[0073] That is, the estimation unit 60 may also estimate the tension based on the difference D'1 between the torque command when the wire electrode 12 is tensioned and a predetermined torque command of the selected motor 38'. The predetermined torque command is the torque command of the selected motor 38' when the wire electrode 12 is deflected, broken, or when the third roller 42 is separated from the wire electrode 12.

[0074] The larger the difference D'1 is, the greater the tension of the wire electrode 12 is. Therefore, according to this modification example, the change in the tension of the wire electrode 12 can be estimated based on the change in the difference D'1.

[0075] (Modification Example 2)

[0076] The predetermined load is also obtained as the difference D2 between the disturbance load of the selected motor 38' when the reverse torque of the torque generating mechanism 35 is a predetermined large value and the disturbance load of the selected motor 38' when the reverse torque of the torque generating mechanism 35 is zero, with the rotational speed of the feed motor 38 fixed. In addition, in this modification example, "the rotational speed of the feed motor 38 is fixed" means that the rotational speed of the first motor 38A is fixed at the first command speed, and the rotational speed of the second motor 38B is fixed at the second command speed. As described in the embodiment, the second command speed is the high speed among the first command speed and the second command speed.

[0077] When obtaining the difference D2, in addition to the disturbance load of the selected motor 38' when the reverse torque of the torque generating mechanism 35 is a predetermined large value, it is also necessary to previously obtain the disturbance load of the selected motor 38' when the reverse torque of the torque generating mechanism 35 is zero. Here, as described below, the disturbance load of the selected motor 38' when the reverse torque of the torque generating mechanism 35 is zero can be estimated based on the correlation (first correlation) between the disturbance load of the selected motor 38' and the torque of the torque generating mechanism 35.

[0078] Figure 6It is a graph showing the correlation between the interference load of the selected motor 38' and the torque (reverse torque) of the torque generation mechanism 35. In addition, in Figure 6 it shows the correlation when the selected motor 38' is the first motor 38A, and uses "T' 35 " to represent the predetermined magnitude of the reverse torque generated by the torque generation mechanism 35.

[0079] As Figure 6 shown, by setting the vertical axis to the interference load (the interference load of the selected motor 38') and the horizontal axis to the torque (reverse torque) of the torque generation mechanism 35, the above-mentioned correlation can be represented by a straight line.

[0080] Figure 7 It is a simplified structural diagram of the control device 16 of Modification 2.

[0081] As Figure 7 shown, the control device 16 of this modification is different from the embodiment in that it further includes a relationship determination unit 68. The relationship determination unit 68 determines the above-mentioned correlation relationship ( Figure 6 the straight line). More specifically, the relationship determination unit 68 first calculates the slope of the straight line representing the correlation relationship, and then determines Figure 6 the straight line based on this slope, thereby determining the correlation relationship.

[0082] In order to calculate the slope of the straight line, the relationship determination unit 68 instructs the torque generation mechanism control unit (torque motor control unit) 66 to generate a reverse torque of the first magnitude through the torque generation mechanism 35 (torque motor 36). In addition, the relationship determination unit 68 instructs the acquisition unit 58 to acquire the interference load of the selected motor 38' at this time. In addition, the magnitude of the reverse torque at this time, that is, the first magnitude, may not be the predetermined magnitude when the conveyor line electrode 12 is used, and may not be zero.

[0083] Next, the relationship determination unit 68 instructs the torque generation mechanism control unit 66 to generate a reverse torque of the second magnitude through the torque generation mechanism 35. In addition, the relationship determination unit 68 instructs the acquisition unit 58 to acquire the interference load of the selected motor 38' at this time. In addition, the magnitude of the reverse torque at this time, that is, the second magnitude, only needs to be different from the first magnitude, and may not be the predetermined magnitude when the conveyor line electrode 12 is used, and may not be zero.

[0084] Then, the relationship determination unit 68 calculates based on the first magnitude and the second magnitude commanded to the torque generation mechanism control unit 66 and the two interference loads acquired by the acquisition unit 58 Figure 6The slope of the straight line. That is, as is generally well-known, the slope of a straight line refers to the change in the change in the vertical axis relative to the change in the horizontal axis. In the case of this modified example, the change in the horizontal axis is the difference between the first magnitude and the second magnitude of the command to the torque generating mechanism control unit 66. In addition, the change in the vertical axis is the difference between the disturbance load of the selected motor 38' when the reverse torque of the torque generating mechanism 35 is the first largest and the disturbance load of the selected motor 38' when the reverse torque of the torque generating mechanism 35 is the second largest.

[0085] If the slope is obtained, it is easy to determine the Figure 6 straight line representing the correlation. In addition, if the straight line representing the correlation is determined, it is easy to obtain the difference D2. The estimation unit 60 estimates a predetermined load based on the difference D2, and thus can easily estimate the tension of the wire electrode 12 based on the predetermined load.

[0086] In this way, according to this modified example, the estimation unit 60 can estimate the tension based on the predetermined load obtained without causing the wire electrode 12 to bend or break and the disturbance load of the selected motor 38' when the wire electrode 12 is tensioned.

[0087] (Modified Example 3)

[0088] Modified Example 2 can also be applied to the case of estimating the tension based on the torque command. In addition, in this case, replace the "disturbance load" in Modified Example 2 with "torque command", replace the "predetermined load" with "predetermined torque command", replace the "first correlation" with "second correlation", and replace the "difference D2" with "difference D'2", so the description is omitted here.

[0089] According to this modified example, the estimation unit 60 can estimate the tension based on the predetermined torque command obtained without causing the wire electrode 12 to bend or break and the torque command of the selected motor 38' when the wire electrode 12 is tensioned.

[0090] (Modified Example 4)

[0091] In the embodiment, it is described that the reverse torque of the torque generating mechanism 35 is adjusted according to the change in the radius R2 of the bobbin 30. However, it is not limited thereto, and the reverse torque of the torque generating mechanism 35 can also be fixed to a predetermined magnitude, and the predetermined load and the predetermined torque command can be adjusted according to the change in the radius R2 of the bobbin 30.

[0092] That is, the magnitude of a predetermined load corresponding to the radius R2 of the spool 30 when the reverse torque of the torque generating mechanism 35 is fixed can be sequentially calculated by Equation (2). By sequentially updating the predetermined load based on the calculation result of the calculation unit 62, similarly to the embodiment, it is possible to prevent the predetermined load used by the estimation unit 60 in the estimation from deviating from the disturbance load generated by disturbances other than the tension. Thus, the estimation unit 60 can accurately estimate the tension of the wire electrode 12 based on the predetermined load.

[0093] (Modification 5)

[0094] So far, in the embodiment and each modification, it has been described that the acquisition unit 58 acquires either the disturbance load or the torque command, and the estimation unit 60 estimates the tension based on either the acquired disturbance load or torque command. However, it is not limited thereto, and the acquisition unit 58 may acquire both the disturbance load and the torque command. In addition, the estimation unit 60 may estimate the tension based on the acquired disturbance load and torque command, respectively. The estimation method in this case may be appropriately selected from the estimation methods described in the embodiment and Modifications 1-4.

[0095] In this modification, the tension estimated based on the disturbance load and the tension estimated based on the torque command can be obtained. The estimation unit 60 determines the average value of the multiple estimated tensions as its estimation result. Thus, even if either the tension estimated based on the disturbance load or the tension estimated based on the torque command is affected by noise, the influence of the noise on the tension obtained as the estimation result can be reduced.

[0096] (Modification 6)

[0097] Figure 8 It is a simplified structural diagram of the control device 16 of Modification 6.

[0098] In association with Modification 5, the control device 16 may further include an abnormality estimation unit 70. When estimating the tension based on the disturbance load and the torque command, respectively, the abnormality estimation unit 70 determines whether the deviation between the tensions based on the disturbance load and the torque command exceeds a predetermined range. Through this determination, for example, when the deviation exceeds the predetermined range, the abnormality estimation unit 70 estimates that there may be a malfunction in the wire electrical discharge machine 10.

[0099] Thus, not only can the tension be estimated, but it is also possible to estimate whether there may be a malfunction in the wire electrical discharge machine 10 based on the estimated tension.

[0100] Moreover, the abnormality estimation unit 70 can further estimate the cause of the deviation exceeding a predetermined range by continuously monitoring the change of the deviation. For example, if the deviation exceeding the predetermined range is temporary, the abnormality estimation unit 70 estimates that the deviation is caused only by the influence of noise. In addition, if the deviation exceeding the predetermined range continues, it is estimated that there is a faulty part in the wire electrical discharge machine 10.

[0101] According to this modification example, the maintenance of the wire electrical discharge machine 10 becomes easy. In addition, this modification example can also estimate an abnormality based on the deviation between the tension estimated by one of the first motor 38A and the second motor 38B and the tension estimated by the other. In this case, at least one of the disturbance load and the torque command of the feed motor 38 that is not the selected motor 38' among the first motor 38A and the second motor 38B is required. This can be achieved by making the acquisition unit 58 further acquire at least one of the disturbance load and the torque command of the feed motor 38 that is not the selected motor 38'.

[0102] (Modification Example 7)

[0103] The above-described embodiments and modification examples can be arbitrarily combined within a range that does not cause contradictions.

[0104] [Invention Obtained from the Embodiment]

[0105] The inventions that can be grasped based on the above-described embodiments and modification examples are described below.

[0106] <First Invention>

[0107] A control device (16) for a wire electrical discharge machining machine (10), wherein the wire electrical discharge machining machine (10) includes: a spool (30) that winds a wire electrode (12); a first roller (32A) that conveys the wire electrode (12) wound around the spool (30) to a workpiece (25) by rotation; a second roller (32B) that conveys the wire electrode (12) that has passed through the workpiece (25) to a recovery box (24) by rotation; a first motor (38A) that rotates the first roller (32A); and a second motor (38B) that rotates the second roller (32B), wherein the control device (16) includes: an acquisition unit (58) that acquires at least one of an interference load based on a drive current of a selected one of the first motor (38A) and the second motor (38B), i.e., a selected motor (38'), and a torque command for rotating at a predetermined command speed; a feed motor control unit (64) that controls the first motor (32A) and the second motor (32B) to tension the wire electrode (12) between the first roller (32A) and the second roller (32B); and an estimation unit (60) that estimates the tension of the tensioned wire electrode (12) based on at least one of the interference load and the torque command acquired by the acquisition unit (58) when the wire electrode (12) is tensioned between the first roller (32A) and the second roller (32B).

[0108] Accordingly, a control device (16) for a wire electrical discharge machining machine (10) is provided, which estimates the tension of the wire electrode (12) based on information obtained from a motor (38') included in a feed mechanism (22) of the wire electrode (12).

[0109] Alternatively, the estimation unit (60) may estimate the tension based on at least one of a difference (D1) between the interference load when the wire electrode (12) is tensioned and a predetermined load, and a difference (D'1) between the torque command when the wire electrode (12) is tensioned and a predetermined torque command. Thereby, the tension can be estimated easily and with high accuracy.

[0110] Alternatively, the predetermined load may be the disturbance load of the selected motor (38') when the first motor (38A) and the second motor (38B) rotate in such a manner that the wire electrode (12) deflects between the first roller (38A) and the second roller (38B), and the predetermined torque command may be the torque command of the selected motor (38') when the first motor (38A) and the second motor (38B) rotate in such a manner that the wire electrode (12) deflects between the first roller (32A) and the second roller (32B). Thus, the tension can be easily and highly accurately estimated.

[0111] Alternatively, the predetermined load may be the disturbance load of the selected motor (38') when the wire electrode (12) that is tensioned and conveyed between the first roller (32A) and the second roller (32B) breaks, and the predetermined torque command may be the torque command of the selected motor (38') when the wire electrode (12) that is tensioned and conveyed between the first roller (32A) and the second roller (32B) breaks. Thus, the tension can be easily and highly accurately estimated.

[0112] Alternatively, the wire electrical discharge machine (10) further includes a pinch roller (42) that applies frictional force to the wire electrode (12) by clamping the wire electrode (12) together with the second roller (32B). The predetermined load may be the disturbance load of the selected motor (38') when the pinch roller (42) disengages from the wire electrode (12) that is tensioned and conveyed, and the predetermined torque command may be the torque command of the selected motor (38') when the pinch roller (42) disengages from the wire electrode (12) that is tensioned and conveyed. Thus, the tension can be easily and highly accurately estimated.

[0113] Alternatively, the wire electrical discharge machine (10) further includes: a torque generating mechanism (35) connected to the spool (30) to generate a reverse torque of a predetermined magnitude, the reverse torque being a torque in a direction opposite to the rotation direction for feeding the wire electrode (12) in the feeding direction. The predetermined load is the difference (D2) between the disturbance load of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is the predetermined magnitude and the disturbance load of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is zero, with the first motor (38A) and the second motor (38B) rotating at fixed rotational speeds respectively. The predetermined torque command is the difference (D'2) between the torque command of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is the predetermined magnitude and the torque command of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is zero, with the first motor (38A) and the second motor (38B) rotating at fixed rotational speeds respectively. Thus, the tension can be easily and highly accurately estimated.

[0114] The first invention further includes: a relationship determination unit (68) that determines at least one of a first correlation relationship that is a correlation relationship between the disturbance load and the reverse torque and a second correlation relationship that is a correlation relationship between the torque command and the reverse torque. The relationship determination unit (68) determines the first correlation relationship based on the disturbance load of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the first largest and the disturbance load of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the second largest. The relationship determination unit (68) determines the second correlation relationship based on the torque command of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the first largest and the torque command of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the second largest. The estimation unit (60) estimates the difference between the disturbance load of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the predetermined size and the disturbance load of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is zero based on the first correlation relationship. The estimation unit (60) estimates the difference between the torque command of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the predetermined size and the torque command of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is zero based on the second correlation relationship. Thus, a predetermined load and a predetermined torque command can be obtained without causing the wire electrode (12) to flex or break.

[0115] The first invention further includes: a calculation unit (62) that sequentially calculates the radius (R2) of the spool (30) including the wound wire electrode (12) based on the feed amount of the wire electrode (12); and a torque generation mechanism control unit (66) that changes the predetermined torque of the torque generation mechanism (35) according to the calculated radius (R2), thereby sequentially adjusting the predetermined load and the predetermined torque command to a fixed size. Thus, the estimation unit (60) can keep the predetermined load and the predetermined torque command fixed while accurately and continuously estimating the tension of the wire electrode (12).

[0116] The first invention further includes: a calculation unit (62) that calculates the radius (R2) of the spool (30) including the wound wire electrode (12) based on the feed amount of the wire electrode (12), and sequentially calculates the predetermined load and the predetermined torque command corresponding to the calculated radius (R2). Thereby, the estimation unit (60) can maintain the reverse torque of the torque generating mechanism (35) at a predetermined magnitude while accurately and continuously estimating the tension of the wire electrode (12).

[0117] Alternatively, the acquisition unit (58) may acquire two of the disturbance load and the torque command of the first motor (38A), and the disturbance load and the torque command of the second motor (38B). The estimation unit (60) estimates the tension based on one of the acquired disturbance load and torque command of the first motor (38A) and the disturbance load and torque command of the second motor (38B), and further estimates the tension based on the other. The first invention further includes: an abnormality estimation unit (70) that estimates whether an abnormality has occurred based on whether the deviation between the two tensions estimated by the estimation unit (60) exceeds a predetermined threshold. Thereby, it is possible to estimate whether an abnormality has occurred based on the estimated tension.

[0118] <Second Invention>

[0119] A method for estimating a wire electrical discharge machining machine (10), the wire electrical discharge machining machine (10) comprising: a spool (30) that winds a wire electrode (12); a first roller (32A) that conveys the wire electrode (12) wound around the spool (30) to a workpiece (25) by rotation; a second roller (32B) that conveys the wire electrode (12) that has passed through the workpiece (25) to a recovery box (24) by rotation; a first motor (38A) that rotates the first roller (32A); and a second motor (38B) that rotates the second roller (32B), the estimation method estimating the tension of the wire electrode (12) tensioned between the first roller (32A) and the second roller (32B), wherein the estimation method includes the following steps: a feed motor control step of controlling the first motor (38A) and the second motor (38B) to tension the wire electrode (12) between the first roller (32A) and the second roller (32B), and obtaining at least one of an interference load based on a drive current and a torque command for rotating at a predetermined command speed for a selected motor (38') that is one of the first motor (38A) and the second motor (38B); and an estimation step of estimating the tension based on at least one of the interference load and the torque command when the wire electrode (12) is tensioned between the first roller (32A) and the second roller (32B).

[0120] Thereby, an estimation method for estimating the tension of the wire electrode (12) based on information obtained from the motor (38') included in the feed mechanism (22) of the wire electrode (12) is provided.

[0121] In the estimation step, the tension may also be estimated based on at least one of a difference (D1) between the interference load when the wire electrode (12) is tensioned and a predetermined load and a difference (D'1) between the torque command when the wire electrode (12) is tensioned and a predetermined torque command. Thereby, the tension can be estimated easily and with high precision.

[0122] Alternatively, the predetermined load may be the disturbance load of the selected motor (38') when the first motor (38A) and the second motor (38B) are rotated in such a manner that the wire electrode (12) flexes between the first roller (32A) and the second roller (32B), and the predetermined torque command may be the torque command of the selected motor (38') when the first motor (38A) and the second motor (38B) are rotated in such a manner that the wire electrode (12) flexes between the first roller (32A) and the second roller (32B). Thus, the tension can be easily and highly accurately estimated.

[0123] Alternatively, the predetermined load may be the disturbance load of the selected motor (38') when the wire electrode (12) that is tensioned and conveyed between the first roller (32A) and the second roller (32B) breaks, and the predetermined torque command may be the torque command of the selected motor (38') when the wire electrode (12) that is tensioned and conveyed between the first roller (32A) and the second roller (32B) breaks. Thus, the tension can be easily and highly accurately estimated.

[0124] Alternatively, the wire electrical discharge machine (10) may further include a pinch roller (42) that applies frictional force to the wire electrode (12) by clamping the wire electrode (12) together with the second roller (32B), the predetermined load may be the disturbance load of the selected motor (38') when the pinch roller (42) is separated from the wire electrode (12) that is tensioned and conveyed, and the predetermined torque command may be the torque command of the selected motor (38') when the pinch roller (42) is separated from the wire electrode (12) that is tensioned and conveyed. Thus, the tension can be easily and highly accurately estimated.

[0125] The wire electrical discharge machine (10) further includes: a torque generation mechanism (35) connected to the spool (30) to generate a reverse torque of a predetermined magnitude, the reverse torque being a torque in a direction opposite to the rotation direction for feeding the wire electrode (12) in the feeding direction. The predetermined load is the difference (D2) between the disturbance load of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the predetermined magnitude and the disturbance load of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is zero, in the case where the first motor (38A) and the second motor (38B) rotate at fixed rotational speeds respectively. The predetermined torque command is the difference (D'2) between the torque command of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is the predetermined magnitude and the torque command of the selected motor (38') when the reverse torque of the torque generation mechanism (35) is zero, in the case where the first motor (38A) and the second motor (38B) rotate at fixed rotational speeds respectively. Thus, the tension can be easily and highly accurately estimated.

[0126] The second invention further includes: a relationship determination step that determines at least one of a first correlation relationship that is a correlation relationship between the disturbance load and the reverse torque and a second correlation relationship that is a correlation relationship between the torque command and the reverse torque. In the relationship determination step, based on the disturbance load of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is at a first magnitude and the disturbance load of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is at a second magnitude, the first correlation relationship is determined. Based on the torque command of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is at the first magnitude and the torque command of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is at the second magnitude, the second correlation relationship is determined. In the estimation step, based on the first correlation relationship, the difference (D2) between the disturbance load of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is at the predetermined magnitude and the disturbance load of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is zero is estimated. Based on the second correlation relationship, the difference (D'2) between the torque command of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is at the predetermined magnitude and the torque command of the selected motor (38') when the reverse torque of the torque generating mechanism (35) is zero is estimated. Thereby, a predetermined load and a predetermined torque command can be obtained without causing the wire electrode (12) to bend or break.

[0127] The second invention may further include: a calculation step that sequentially calculates the radius (R2) of the spool (30) that includes the wound wire electrode (12) based on the feed amount of the wire electrode (12); and a torque generating mechanism control step that changes the predetermined torque of the torque generating mechanism (35) according to the calculated radius (R2), thereby sequentially adjusting the predetermined load and the predetermined torque command to a fixed magnitude. Thereby, in the estimation step, a predetermined load and a predetermined torque command can be maintained as fixed while accurately and continuously estimating the tension of the wire electrode (12).

[0128] The second invention may further include: a calculation step that calculates the radius (R2) of the spool (30) that includes the wound wire electrode (12) based on the feed amount of the wire electrode (12), and sequentially calculates the predetermined load and the predetermined torque command corresponding to the calculated radius (R2). Thereby, in the estimation step, the reverse torque of the torque generating mechanism (35) can be maintained at a predetermined magnitude while accurately and continuously estimating the tension of the wire electrode (12).

[0129] In the feed motor control step, two of the disturbance load and the torque command of the first motor (38A), and the disturbance load and the torque command of the second motor (38B) are obtained. In the estimation step, the tension is estimated based on one of the obtained disturbance load and the torque command of the first motor (38A), and the disturbance load and the torque command of the second motor (38B), and the tension is further estimated based on the other. The second invention further includes an abnormality estimation step of estimating whether an abnormality has occurred based on whether the deviation between the two tensions estimated in the estimation step exceeds a predetermined threshold. Thus, it is possible to estimate whether an abnormality has occurred based on the estimated tension.

Claims

1. A control device (16) for a wire electrical discharge machining machine (10), the wire electrical discharge machining machine (10) comprising: A bobbin (30) that winds a wire electrode (12); A first roller (32A) that conveys the wire electrode wound around the bobbin to a workpiece (25) by rotation; A second roller (32B) that conveys the wire electrode that has passed through the workpiece to a recovery box (24) by rotation; A first motor (38A) that rotates the first roller; and A second motor (38B) that rotates the second roller, Characterized in that, The control device (16) of the wire electrical discharge machining machine (10) comprises: An acquisition unit (58) that acquires at least one of a disturbance load based on a drive current of a selected one of the first motor and the second motor, i.e., the selected motor (38'), and a torque command for rotating at a predetermined command speed; A feed motor control unit (64) that controls the first motor and the second motor to keep the wire electrode taut between the first roller and the second roller; and An estimation unit (60) that controls the tension of the taut wire electrode based on at least one of the disturbance load and the torque command acquired by the acquisition unit when the wire electrode is taut between the first roller and the second roller, The estimation unit estimates the tension based on at least one of a difference (D1) between the disturbance load when the wire electrode is taut and a predetermined load, and a difference (D'1) between the torque command when the wire electrode is taut and a predetermined torque command.

2. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that, The predetermined load is the disturbance load of the selected motor when the first motor and the second motor rotate in such a way that the wire electrode bends between the first roller and the second roller, The predetermined torque command is the torque command of the selected motor when the first motor and the second motor rotate in such a way that the wire electrode bends between the first roller and the second roller.

3. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that, The predetermined load is the disturbance load of the selected motor when the wire electrode that is taut and conveyed between the first roller and the second roller breaks, The predetermined torque command is the torque command of the selected motor when the wire electrode that is taut and conveyed between the first roller and the second roller breaks.

4. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that, The wire electrical discharge machining machine further comprises: a pinch roller (42) that applies frictional force to the wire electrode by clamping the wire electrode together with the second roller, The predetermined load is the disturbance load of the selected motor when the pinch roller is separated from the wire electrode that is taut and conveyed. The predetermined torque command is the torque command of the selected motor when the pinch roller is separated from the wire electrode that is tensioned and being conveyed.

5. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that the wire electrical discharge machining machine further includes: a torque generating mechanism (35) connected to the spool, which generates a reverse torque of a predetermined magnitude, and the reverse torque is a torque in a direction opposite to the rotation direction for conveying the wire electrode in the feeding direction. The predetermined load is the difference (D2) between the disturbance load of the selected motor when the reverse torque of the torque generating mechanism is the predetermined magnitude and the disturbance load of the selected motor when the reverse torque of the torque generating mechanism is zero, when the first motor and the second motor rotate at a fixed rotational speed respectively. The predetermined torque command is the difference (D'2) between the torque command of the selected motor when the reverse torque of the torque generating mechanism is the predetermined magnitude and the torque command of the selected motor when the reverse torque of the torque generating mechanism is zero, when the first motor and the second motor rotate at a fixed rotational speed respectively.

6. The control device for a wire electrical discharge machining machine according to claim 5, characterized in that the control device further includes: a relationship determination unit (68) that determines at least one of a first correlation relationship that is a correlation relationship between the disturbance load and the reverse torque and a second correlation relationship that is a correlation relationship between the torque command and the reverse torque. The relationship determination unit determines the first correlation relationship based on the disturbance load of the selected motor when the reverse torque of the torque generating mechanism is a first magnitude and the disturbance load of the selected motor when the reverse torque of the torque generating mechanism is a second magnitude, and determines the second correlation relationship based on the torque command of the selected motor when the reverse torque of the torque generating mechanism is a first magnitude and the torque command of the selected motor when the reverse torque of the torque generating mechanism is a second magnitude. The estimation unit estimates the difference between the disturbance load of the selected motor when the reverse torque of the torque generating mechanism is the predetermined magnitude and the disturbance load of the selected motor when the reverse torque of the torque generating mechanism is zero based on the first correlation relationship, and estimates the difference between the torque command of the selected motor when the reverse torque of the torque generating mechanism is the predetermined magnitude and the torque command of the selected motor when the reverse torque of the torque generating mechanism is zero based on the second correlation relationship.

7. The control device for a wire electrical discharge machining machine according to claim 5 or 6, characterized in that the control device further includes: a calculation unit (62) that sequentially calculates the radius (R2) of the spool including the wound wire electrode based on the feed amount of the wire electrode. The torque generation mechanism control unit (66) changes the predetermined torque of the torque generation mechanism according to the calculated radius, thereby adjusting the predetermined load and the predetermined torque command to fixed magnitudes in sequence.

8. The control device for a wire electrical discharge machining machine according to any one of claims 1 to 6, characterized in that: The control device further includes: a calculation unit (62) that calculates the radius (R2) of the spool including the wound wire electrode based on the feed amount of the wire electrode, and sequentially calculates the predetermined load and the predetermined torque command corresponding to the calculated radius.

9. The control device for a wire electrical discharge machining machine according to any one of claims 1 to 6, characterized in that: The acquisition unit acquires two of the disturbance load and the torque command of the first motor, and the disturbance load and the torque command of the second motor. The estimation unit estimates the tension based on one of the disturbance load and the torque command of the first motor and the disturbance load and the torque command of the second motor acquired, and further estimates the tension based on the other acquired. The control device for a wire electrical discharge machining machine further includes: an abnormality estimation unit (70) that estimates whether an abnormality has occurred based on whether the deviation between the two tensions estimated by the estimation unit exceeds a predetermined threshold.

10. A method for estimating a wire electrical discharge machining machine (10), the wire electrical discharge machining machine (10) including: A spool (30) that winds a wire electrode (12); A first roller (32A) that conveys the wire electrode wound around the spool to a workpiece to be machined by rotation; A second roller (32B) that conveys the wire electrode that has passed through the workpiece to a recovery box (24) by rotation; A first motor (38A) that rotates the first roller; and A second motor (38B) that rotates the second roller, The estimation method estimates the tension of the wire electrode tensioned between the first roller and the second roller. Characterized in that: The estimation method includes: A feed motor control step of controlling the first motor and the second motor to tension the wire electrode between the first roller and the second roller, and for the selected motor (38') which is one of the first motor and the second motor, acquiring at least one of the disturbance load based on the drive current and the torque command for rotating at a predetermined command speed. And An estimation step of estimating the tension based on at least one of the disturbance load and the torque command when the wire electrode is tensioned between the first roller and the second roller. In the estimation step, the tension is estimated based on at least one of the difference (D1) between the disturbance load when the wire electrode is tensioned and a predetermined load, and the difference (D'1) between the torque command when the wire electrode is tensioned and a predetermined torque command.

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