JP5037895B2 - Electric discharge machining apparatus and electric discharge machining method - Google Patents

Description

  The present invention relates to an electric discharge machining apparatus and an electric discharge machining method.

  In machining a workpiece in a conventional electric discharge machining apparatus, there is a possibility that the wire is disconnected due to interference between the water column and the workpiece thickness changing portion due to the nozzle diameter for discharging the machining fluid. Therefore, a technique for preventing wire breakage during wire electric discharge machining has been proposed (see, for example, Patent Document 1). The electric discharge machining apparatus of Patent Document 1 includes a machining condition storage unit that stores machining conditions when a nozzle is in close contact with a workpiece, a liquid flow rate database that stores a relationship between a plate thickness, a nozzle height, and a liquid flow rate, A liquid flow rate determining means for determining a liquid flow rate in rough machining based on this relationship, and a controller for performing electric discharge machining based on the determined liquid flow rate are provided. When the nozzle height is input, the liquid flow rate corresponding to the plate thickness, the upper nozzle height, and the lower nozzle height is extracted from the liquid flow rate database and determined.

International Publication No. 02/034445 Pamphlet

  By the way, the determination of the processing conditions when processing the workpiece in the above-described conventional technique is performed by assuming that the workpiece is a flat plate, that is, assuming that there is no change in the thickness of the workpiece. Then, the entire workpiece is processed under the determined processing conditions. However, there are many cases where a workpiece processed by an actual electric discharge machining apparatus is not a flat plate, and there are steps or holes on the wire machining path, and the thickness of the workpiece may change in the machining range.

  The machining fluid flow rate control in the conventional technology only controls the machining fluid flow rate according to the plate thickness of the entire workpiece. Machining of the vicinity of a characteristic shape causes disturbance of the machining fluid, and the machining servo The processing when it is difficult to remove is not taken into consideration, and there is a problem in that wire breakage occurs with changes in the flow rate of the working fluid.

  The present invention has been made in view of the above, and when wire EDM is performed on a workpiece having a shape that is likely to cause breakage on a machining path, the wire breakage does not occur and an appropriate reduction in machining speed is minimized. An object is to obtain an electric discharge machining apparatus and an electric discharge machining method in which machining is performed.

In order to achieve the above object, an electric discharge machining apparatus according to the present invention is directed to a wire for electric discharge machining a workpiece to be machined into a predetermined shape, and from the extending direction of the wire to a machining portion of the wire and the workpiece. In an electric discharge machining apparatus comprising: a nozzle for supplying machining fluid; and numerical control means for processing the workpiece using the wire based on a numerical control program, on a machining path defined by the numerical control program The shape change position at which the plate thickness of the workpiece changes and the type of the shape are extracted, and the range before and after the shape change position at which the change in the plate thickness of the workpiece affects the electric discharge machining process is a condition a machining path information creating means for creating a machining route information set on the machining path as a change area, the current processing progress of the wire at the work during the electric discharge machining process Machining progress position obtaining means for obtaining a position, machining condition storage means for storing machining conditions in the condition change region for each type of shape formed on the workpiece, and current conditions obtained by the machining progress position obtaining means When the machining progress position reaches the condition change area in the machining path information, the machining condition setting corresponding to the shape type is acquired from the machining condition storage unit and set as a new machining condition. And the numerical control means executes an electric discharge machining process based on the machining conditions set by the machining condition setting means.

  According to the present invention, since control is performed according to the shape characteristics of the workpiece during electric discharge machining, even when the machining fluid flow is disturbed due to the machining shape change position existing on the machining path or in the vicinity of the machining path, the wire It has the effect that disconnection can be prevented.

  Exemplary embodiments of an electric discharge machining apparatus and an electric discharge machining method according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram schematically showing a functional configuration of a first embodiment of an electric discharge machining apparatus according to the present invention. The electric discharge machining apparatus 10 includes a three-dimensional shape information storage unit 11, an NC program storage unit 12, a machining path upper plate thickness information acquisition unit 13, a machining path information creation unit 14, a machining path information storage unit 15, and a machining progress position acquisition unit. 16, a processing condition storage unit 17, a processing condition determination unit 18, a processing condition change unit 19, an output / display unit 20, a numerical control unit 21, and a control unit 22 that controls these processing units.

  The three-dimensional shape information storage unit 11 stores three-dimensional shape information of a workpiece that is a machining target. The three-dimensional shape information is configured by a set of data such as coordinates and thicknesses at the coordinate positions of the shape of a workpiece to be processed. As this three-dimensional shape information, data created by CAD (Computer-Aided Design) can be used. The three-dimensional shape information also includes shape names (holes, steps, etc.) indicating what the shape of each shape characteristic portion in the data is. A technique for identifying and setting the shape of each shape feature in this data is known (for example, see Japanese Patent Application Laid-Open No. 2006-142396 and International Publication No. 01/081035 pamphlet). Omitted. The three-dimensional shape data is created or input by the user of the electric discharge machining apparatus 10.

  The NC program storage unit 12 stores an NC program for machining a workpiece. This NC program includes a machining path for machining a workpiece and machining conditions at a predetermined position on the machining path.

  The machining path thickness information acquisition unit 13 superimposes the 3D shape information of the workpiece in the 3D shape information storage unit 11 and the machining path of the NC program, and acquires the machining path thickness information. The plate thickness information on the machining path is stored in the machining path information storage unit, and the machining path of the NC program is developed in one direction to show the plate thickness at each point on the machining path. That is, the plate thickness corresponding to the processing distance is expressed. It is assumed that the coordinate system in the three-dimensional shape information and the coordinate system in the NC program are the same.

  The machining path information creation unit 14 extracts a shape change position on the machining path, and sets a predetermined range as a condition change region from the shape change position. Specifically, when the wire is viewed as a point on the top view (plan view) of the workpiece, the position at which the thickness of the workpiece changes when this point is moved along the machining path of the NC program Is extracted as a shape change position.

  Thereafter, a predetermined range machining fluid ejection nozzle radius on the machining path centering on the shape change position is set as the condition change region. The nozzle radius is usually about 1 mm. The condition change area is an area that affects the electric discharge machining process by changing the shape of the workpiece, and is set as an area for setting machining conditions different from other normal positions. As shown in FIG. 7-2 to be described later, these shape change position and condition change region are added to the plate thickness information and stored in the machining path information storage unit 15 as machining path information. In this specification, a portion where the thickness of the workpiece changes is called a shape feature. Further, the machining path information creation unit 14 may extract a part where the plate thickness changes from the plate thickness information on the machining path acquired by the machining path plate thickness information acquisition unit 13 as a shape change position. The machining path information creation unit 14 corresponds to machining path information creation means in the claims.

  The machining path information storage unit 15 includes a machining path upper plate thickness information acquired by the machining path upper plate thickness information acquisition unit 13, and a shape change position and a condition change region extracted by the machining path information creation unit 14. Stores route information.

  The machining progress position acquisition unit 16 acquires a machining progress position that indicates where the wire is actually present on the workpiece during wire electric discharge machining. The processing progress position acquisition unit 16 corresponds to processing progress position acquisition means in the claims.

  The machining condition storage unit 17 stores machining conditions obtained in advance so that wire breakage does not occur for each type of shape present in the workpiece being machined. The machining conditions include mechanical conditions such as the moving speed of the wire and electrical conditions such as machining energy in electric discharge machining. FIG. 2 is a diagram illustrating an example of processing conditions. The machining conditions include information including the shape of the workpiece (shape name) and the machining conditions for the shape. In this example, the machining conditions indicate the percentage of the value at which machining is performed compared to the machining conditions at the normal position (specified in the NC program), but the machining speed, machining energy, etc. The mechanical conditions and electrical conditions may be determined more specifically. The machining condition storage unit 17 corresponds to the machining condition storage means in the claims.

  The machining condition determination unit 18 determines whether or not the current machining progress position acquired by the machining progress position acquisition unit 16 is in the condition change area. If the current machining progress position is in the condition change area, Based on the machining conditions in the machining condition storage unit 17, a process for determining a machining condition to be performed at the next position on the machining path is performed. At this time, the shape name included in the three-dimensional shape information is used for the shape of the condition change region.

  The machining condition changing unit 19 changes and sets the machining conditions performed based on the NC program to the machining conditions determined by the machining condition determining unit 18. The machining condition determination unit 18 and the machining condition change unit 19 correspond to the machining condition setting unit in the claims.

  The output / display unit 20 has a function of visually displaying three-dimensional shape information, an NC program, a condition change area, and the like based on a predetermined display program. Generally, it is configured by a display device such as a liquid crystal display device.

  The numerical controller 21 controls an electric discharge machine (not shown) that performs an actual electric discharge machining process such as a stage on which a wire or a workpiece is placed based on the NC program. When the machining condition is changed by the machining condition changing unit 19, the numerical control unit 21 controls the electric discharge machine based on the changed machining condition. Examples of this control include control of mechanical conditions such as wire feed speed and machining fluid flow rate, and electrical conditions such as discharge energy. The numerical control unit 21 corresponds to numerical control means in the claims.

  In normal control, machining instability is detected and special processing is performed. However, the electric discharge machining apparatus 10 having such a configuration uses machining path information having a condition change area to process machining before it becomes unstable. The machining conditions of the electric discharge machining process are controlled so as not to be stable.

  Next, an electric discharge machining procedure in the electric discharge machining apparatus 10 will be described.

  First, the shape feature extraction process on the processing path will be described with a specific example. FIG. 3 is a flowchart showing an example of a procedure for extracting shape information on a machining path, FIG. 4 is a perspective view showing an example of the shape of a workpiece to be subjected to electric discharge machining, and FIG. 4 is a top view of the workpiece of FIG. 4, and FIG. 6 is a diagram showing a machining path of the workpiece of FIG. In FIG. 6, the shape of the workpiece is indicated by a dotted line in order to make it easy to understand which position on the workpiece passes the machining path.

As shown in FIG. 4, the workpiece 101 has a structure in which a hole 111 and a step 112 are provided in one place on a rectangular parallelepiped workpiece having a thickness of T ₁ . The thickness of the workpiece 101 at the hole 111 is T ₂ , and the thickness of the workpiece 101 at the step 112 is T ₃ . The shape of the workpiece 101 and the type of shape provided on the workpiece 101 are stored in the three-dimensional shape information storage unit 11 as three-dimensional shape information. Further, the NC program 120 representing the machining path shown in FIG. 6 is stored in the NC program storage unit 12.

  First, the plate thickness information acquisition unit 13 on the processing path includes the three-dimensional shape information of the workpiece 101 shown in FIG. 4 from the three-dimensional shape information storage unit 11, and the processing path 120 shown in FIG. 6 from the NC program storage unit 12. Are acquired (step S11).

Next, the processing path thickness information acquisition unit 13 superimposes the processing path 120 on the workpiece 101 (step S12). Thereafter, the plate thickness information acquisition unit 13 on the processing path acquires the thickness of each point on the processing path 120 from the three-dimensional shape information, and creates plate thickness information for the processing path 120 (step S13). FIG. 7A is a diagram illustrating plate thickness information on the machining path illustrated in FIG. 6. In FIG. 7A, the horizontal axis indicates the plate thickness, and the vertical axis indicates each point on the machining path. In the Figure 7-1, are illustrated thick portion T _1, part of the thickness T ₂ there are holes 111, thickness there is a step 112 is the portion of T _3. In this plate thickness information, the machining path 120 shown in two dimensions in FIG. 6 is developed in one direction.

  Next, the machining path information creation unit 14 extracts the shape feature of the workpiece 101 using the acquired plate thickness information. Specifically, the shape change position where the plate thickness is changed is extracted (step S14). Further, the machining path information creation unit 14 sets a predetermined range before and after the shape change position on the machining path 120 as a condition change area (step S15), and creates machining path information. 7-2 is a diagram in which a shape change position is added to the plate thickness information in FIG. 7-1, and FIG. 7-3 is a diagram in which a condition change region is further added to FIG. 7-2. As shown in FIG. 7B, the shape change position indicates a portion where the shape (plate thickness) changes on the machining path 120 in the plate thickness information as a point. Further, as shown in FIG. 7C, the condition change area is shown as a predetermined area before and after the shape change position in FIG. Then, the machining path information shown in FIG. 7C is stored in the machining path information storage unit, and the shape feature extraction process is completed.

  Next, the actual electric discharge machining process will be described with reference to the flowchart of FIG. First, it is assumed that the machining process is started in the electric discharge machining apparatus 10 and the process is proceeding based on the NC program. At this time, the numerical control unit 21 performs an electrical discharge machining process on the workpiece based on predetermined machining conditions defined in the NC program stored in the NC program storage unit 12 (step S31).

  The machining progress position acquisition unit 16 acquires the current machining progress position based on the machining speed of the NC program (step S32). Then, the machining progress position acquisition unit 16 determines whether or not the current machining progress position has reached the condition change region with reference to the machining path information acquired in the shape feature extraction process of FIG. 3 (step S33). ). If the condition change area has not been reached (No in step S33), the processing is continued under the conditions up to that point (step S34).

  On the other hand, when the condition change area is reached (Yes in step S33), the machining condition determination unit 18 acquires the shape name from the machining path information (three-dimensional shape information), and responds to the shape name. The machining conditions are extracted from the machining condition storage unit 17 (step S35). For example, when the current processing progress position reaches the condition change region of the position of the hole 111 in FIG. 5 or FIG. 6, information indicating that the position is a hole is included in the processing path information (three-dimensional shape information). Therefore, the machining condition determination unit 18 extracts a machining condition whose shape name corresponds to “hole” from the machining conditions of FIG. Referring to FIG. 2, since the machining condition with the shape name “hole” is to be machined under the condition of 50% of the normal energy, the machining condition for setting the energy up to that to 50% is determined.

  Thereafter, the machining condition determination unit 18 determines the extracted machining condition as a new machining condition (step S36). This processing condition is a processing condition determined so as not to cause a wire breakage according to the shape feature. Next, the machining condition changing unit 19 changes the machining conditions in the NC program set up to now to the machining conditions determined by the machining condition determining unit 18 (step S37), and the numerical control unit 21 is changed. Then, the electric discharge machining process of the workpiece is executed under the new machining conditions (step S38).

  Thereafter, the machining progress position acquisition unit 16 acquires the current machining progress position in consideration of the new machining conditions (step S39). Then, the machining progress position acquisition unit 16 refers to the machining path information acquired in the shape feature extraction process, and determines whether or not the current machining progress position has reached the outside of the condition change region (step S40). If the condition has not been reached outside the condition change area (No in step S40), the process returns to step S38, and the processing is advanced under the changed processing conditions.

  If the condition change area is reached (Yes in step S40), the machining condition determination unit 18 acquires normal machining conditions defined in the NC program (step S41), and changes the machining conditions. The unit 19 changes the machining condition set so far to the acquired machining condition (step S42). Then, the numerical control unit 21 performs an electric discharge machining process on the workpiece under the changed machining conditions (that is, machining conditions defined in the NC program) (step S43).

  Thereafter or after step S34, the machining progress position acquisition unit 16 acquires the current machining progress position (step S44), and refers to the NC program to determine whether the machining has been completed (step S45). If the machining has not ended, the process returns to step S32, and the above-described processing is repeatedly executed until the machining path reaches the end point. Further, when the machining process is finished, the electric discharge machining process is finished.

  According to the first embodiment, based on the three-dimensional shape information of the workpiece to be machined, a change in the shape feature of the workpiece on the machining path is extracted in advance, and the machining conditions are changed based on the shape feature of the workpiece. As a result, even when the shape feature of the workpiece changes during the progress of machining, there is an effect that wire breakage does not occur and proper machining is performed while minimizing a reduction in machining speed.

Embodiment 2. FIG.
In the first embodiment, a point where the shape feature on the machining path changes is acquired, a predetermined range on the machining path is set as a condition change area from the change point of the shape feature, and the current machining is set in the condition change area. When the advancing position is reached, the machining conditions for electrical discharge machining are changed.

However, in the method of the first embodiment, the machining condition can be changed for the change of the shape feature existing on the machining path. However, when there is a region where the shape feature changes in the vicinity of the machining path, The condition cannot be changed.

  Therefore, there is a possibility that wire breakage may occur when processing such a region. Therefore, in the second embodiment, an electric discharge machining apparatus and an electric discharge machining method capable of controlling machining conditions in consideration of a region in which a shape feature changes in the vicinity of the machining path will be described.

  FIG. 9 is a block diagram schematically showing a functional configuration of the second embodiment of the electric discharge machining apparatus according to the present invention. This electric discharge machining apparatus 10 has a configuration further including a workpiece shape influence range creation unit 23 and a machining fluid influence range creation unit 24 in the electric discharge machining apparatus 10 of FIG.

  The workpiece shape influence range creation unit 23 obtains a workpiece shape influence range which is a range of influences of a shape change portion existing in the workpiece on the wire during electric discharge machining. It has become clear from experiments that the work shape influence range is, for example, about 1 mm in the case of step machining.

  Specifically, a predetermined range in a direction perpendicular to the contour from each point on the contour of the workpiece is regarded as a workpiece shape influence range and superimposed on the three-dimensional shape information of the workpiece. 10-1 to 10-3 are diagrams illustrating an example of a method for acquiring a workpiece shape influence range, FIG. 10-1 is a perspective view illustrating an example of a workpiece shape, and FIG. FIG. 10C is a top view of the workpiece shape of FIG. 10A, and FIG. 10C is a diagram in which the workpiece shape influence range is added to the workpiece shape in FIG. Here, for convenience of explanation, a diagram in which a workpiece shape influence range A ′ is added to the top view of the workpiece 101 is shown. As shown in FIG. 10C, a workpiece shape influence range A ′ is created in a predetermined range outside and inside from the contour A of the workpiece. The workpiece shape influence range creation unit 23 corresponds to the workpiece shape influence range creation means in the claims.

  The machining fluid influence range creation unit 24 obtains a range of the influence of machining fluid supplied from the nozzle to the wire on the wire during electric discharge machining. FIG. 11 is a diagram schematically illustrating the machining liquid influence range. As shown in this figure, a predetermined range from the wire W affected by the machining liquid to the wire W regarded as a point when the machining path is obtained is defined as a machining liquid influence range W ′. This machining liquid influence range W ′ indicates the range of the water column of the wire during actual electric discharge machining. When the nozzle radius of the wire is 2 mm, the water column is also 2 mm, so it has been clarified by experiments that the range of influence of the machining fluid is about 2 mm. The machining fluid influence range creation unit 24 corresponds to the machining fluid influence range creation means in the claims.

  In addition to the setting of the condition change area AW described in the first embodiment, the machining path information creation unit 14 corresponds to the workpiece shape influence range on the machining path (corresponding to the workpiece shape influence range on the machining path in the claims). A'W, machining fluid influence range (corresponding to machining fluid influence range on machining path in claims) AW 'and workpiece shape / fluid influence range (work path machining shape / machining in claims) Processing for obtaining A′W ′ corresponding to the liquid influence range is performed. Specifically, the workpiece shape influence range A′W, which is the intersection between the workpiece shape influence range A ′ and the wire W, and the machining fluid influence range, which is the intersection between the workpiece contour A and the machining fluid influence range W ′. Three-dimensional shape information, machining path, workpiece shape influence range, AW ', and workpiece obtained shape / working fluid influence range A'W' which is the intersection of workpiece shape influence range A 'and machining fluid influence range W' The processing liquid influence range is obtained, and the result is stored in the machining path information storage unit 15 as machining path information. The process of extracting the shape change position by the machining path information creation unit 14 is the same as obtaining the intersection between the workpiece contour A and the wire W. Since other components in the electric discharge machining apparatus 10 of FIG. 9 are the same as those in the first embodiment, detailed description thereof is omitted.

  Next, the shape feature extraction processing of the electric discharge machining apparatus according to the second embodiment will be described with reference to the flowchart of FIG. In addition, here, the work 101 having the shape shown in FIGS. 10A to 10B will be described by taking as an example the case where the electric discharge machining process is performed on the machining path shown by the dotted line in FIG. 10B. And

Referring to the work, as shown in Figure 10-1 Figure 10-2, the thickness of the rectangular parallelepiped of T1 workpiece, midway from the thickness of the processing direction becomes smaller T ₂ than T ₁ step 112 Is provided. The step 112 has a structure in which one hole 111 is provided. The thickness of the work portion of the hole 111 is T _3. The shape of the workpiece 101 is stored in the three-dimensional shape information storage unit 11 as three-dimensional shape information. Further, the NC program representing the machining path indicated by the dotted line in FIG. 10-2 is stored in the NC program storage unit 12.

  Next, the shape feature extraction processing will be described. First, the processing path plate thickness information acquisition unit 13 receives the 3D shape information shown in FIG. 10-1 from the 3D shape information storage unit 11 and the NC program storage unit 12. To obtain the machining path shown in FIG. 10-2 (step S61).

Next, the plate thickness information acquisition unit 13 on the processing path superimposes the processing path on the workpiece as shown in FIG. 10-2 (step S62). Thereafter, the plate thickness information acquisition unit 13 on the processing path acquires the thickness of each point on the processing path from the three-dimensional shape information, and creates the plate thickness information for the processing path (step S63). FIG. 13 shows plate thickness information indicating the plate thickness change on the machining path shown in FIG. 10-2. In FIG. 13, the vertical axis indicates the plate thickness, and the horizontal axis indicates each point on the machining path. In FIG. 13, the portion of the thickness of which is not subjected any processing T1, thickness portion of the T ₂ with a step 112, the thickness, which is formed of holes 111 are shown parts of T ₃ .

  Next, the workpiece shape influence range creation unit 23 creates a workpiece shape influence range having a range that is a predetermined distance away from the contour of the workpieces of FIGS. 10A to 10B (step S64). . As shown in FIG. 10C, a line parallel to the contour A is drawn at a position separated by a predetermined distance s from the contour A of the work 101 to the outside and the inside, and an area sandwiched between these two lines is drawn. The workpiece shape influence range A ′.

  In addition, the machining liquid influence range creation unit 24 creates a machining liquid influence range W ′ having a range that is a predetermined distance t away from the wire W represented by a point in a cross-sectional shape perpendicular to the longitudinal direction of the wire. (Step S65). This is shown in FIG. Here, after the creation of the workpiece shape influence range in step S64, the machining fluid influence range is created in step S65, but the order may be reversed.

  Thereafter, the machining path information creation unit 14 extracts the shape change position where the plate thickness of the workpiece is changed using the plate thickness information acquired in step S63 (step S66). Since this shape change position is the same as the intersection between the outline A of the workpiece 101 and the wire W as described above, it is obtained as the intersection between the outline A of the workpiece and the wire W without using the plate thickness information. Also good.

  Next, the machining path information creation unit 14 performs a process of extracting the workpiece shape influence range A′W that is the intersection between the wire W and the three-dimensional shape information to which the workpiece shape influence range A ′ acquired in step S64 is added. This is performed (step S67). Further, the machining path information creation unit 14 is a machining liquid influence range that is an intersection of the workpiece three-dimensional shape information (work outline A) and the wire shape to which the machining liquid influence range W ′ acquired in step S65 is added. A process of extracting AW ′ is performed (step S68). Furthermore, the workpiece shape / working fluid that is the intersection of the three-dimensional shape information to which the workpiece shape influence range A ′ acquired in step S64 is added and the wire shape to which the machining fluid influence range W ′ acquired in step S65 is added. A process of extracting the influence range A ′ W ′ is performed (step S69). Note that the order of the processes in steps S66 to S69 can also be changed.

  FIG. 14 is a diagram illustrating an example of machining path information in which a shape change position, a workpiece shape influence range, a machining fluid influence range, and a workpiece shape / working fluid influence range are added to the plate thickness information. In the shape change position extraction process, the portion where the shape changes is regarded as the intersection between the contour A of the workpiece three-dimensional shape information and the wire W. Therefore, in the figure, the shape change position is indicated as AW.

  In the workpiece shape influence range extraction process, the intersection of the workpiece shape influence range A ′ and the wire W is regarded as the workpiece shape influence range. Therefore, in the drawing, the workpiece shape influence range is indicated as A'W.

  Further, in the machining fluid influence range extraction process, the intersection between the workpiece shape contour A and the wire to which the machining fluid influence range W ′ is added is regarded as the machining fluid influence range. Therefore, in the drawing, the working fluid influence range is indicated as AW ′.

  Furthermore, in the workpiece shape / working fluid influence range extraction process, the intersection of the wires to which the work shape influence range A ′ and the machining fluid influence range W ′ are added is regarded as the work shape / working fluid influence range. Therefore, in the drawing, the workpiece shape / working fluid influence range is indicated as A'W '. As described above, the shape feature extraction process ends.

  Next, an actual electric discharge machining process will be described with reference to the flowchart of FIG. First, it is assumed that the machining process is started in the electric discharge machining apparatus 10 and the process is proceeding based on the NC program. At this time, the numerical control unit 21 performs an electric discharge machining process on the workpiece according to the machining conditions defined in the NC program (step S91).

  The machining progress position acquisition unit 16 acquires the current machining progress position based on the machining speed of the NC program (step S92). Then, the machining progress position acquisition unit 16 refers to the shape feature information acquired by the shape feature extraction process, and determines whether or not the current machining progress position has reached the condition change region (step S93). If the condition change area has not been reached (No in step S93), electric discharge machining is performed under the conditions up to that point (step S94).

  On the other hand, when the condition change area is reached (Yes in step S93), the machining condition determination unit 18 extracts a machining condition corresponding to the shape state from the machining condition storage unit 17 (step S95). Here, the shape state means an overlapping state of the shape change position AW, the workpiece shape influence range A′W, the machining fluid influence range AW ′, and the workpiece shape / working fluid shadow range A′W ′. Generally, the range becomes smaller in the order of A′W ′> [AW ′, A′W]> AW, and wire breakage is likely to occur in this order. Therefore, the processing conditions are selected based on the processing conditions prepared in advance so as to change the processing conditions in accordance with the overlapping state of these regions.

  FIG. 16 is a diagram illustrating an example of processing conditions. These machining conditions include a shape (shape name) which is a shape feature existing on the workpiece, a shape change position AW, a workpiece shape influence range A′W, a machining fluid influence range AW ′, a workpiece shape / working fluid shadow range A ′. W ′ is composed of items including processing conditions. Here, the processing condition is a condition including an electrical condition and a mechanical condition, and the example of this figure shows how much the processing condition is suppressed as compared with the normal processing. Here, the suppression ratio is indicated by a downward triangle mark. Assuming that one downward triangular mark has a predetermined ratio, two downward triangular marks are suppressed by the double amount, and three downward triangular marks are suppressed by the triple amount. Further, as shown in this figure, the shape change position AW, that is, the shape change position AW, the workpiece shape influence range A′W, the machining fluid influence range AW ′, and the workpiece shape / working fluid shadow range A′W ′ are all included. In the overlapping region, the processing conditions are most suppressed, and the rate of suppression decreases as the distance from the shape change position AW increases, that is, as the overlapping state of the shape state decreases.

  Thereafter, the machining condition determination unit 18 determines the extracted machining condition as a new machining condition (step S96). Next, the machining condition changing unit 19 changes the machining condition that has been set so far to the machining condition determined by the machining condition determining unit 18 (step S97), and the numerical control unit 21 uses the changed machining condition. The workpiece is processed (step S98).

  Thereafter, the processing progress position acquisition unit 16 acquires the current processing progress position in consideration of the new processing conditions (step S99). Then, the machining progress position acquisition unit 16 determines whether or not the current machining progress position has reached the outside of the condition change region with reference to the machining path information acquired in the shape feature extraction process of FIG. S100). If the condition change area has not been reached (No in step S100), it is determined whether or not a different condition change area has been reached (step S101). If the different condition change areas have not been reached (No in step S101), the process returns to step S98, and the processing is advanced under the changed processing conditions. If a different condition change area has been reached (Yes in step S101), the process returns to step S95 and the above-described processing is repeatedly executed.

  If the condition change area is reached (Yes in step S100), the machining condition determination unit 18 acquires normal machining conditions defined in the NC program (step S102), and changes the machining conditions. The unit 19 changes the machining conditions set so far to the acquired machining conditions (step S103). Then, the numerical control unit 21 performs an electric discharge machining process on the workpiece under the changed new machining conditions (that is, machining conditions defined in the NC program) (step S104).

  FIG. 17 is a diagram illustrating an example of machining path information when machining the workpiece of FIG. 10-2. In this figure, the plate thickness information is omitted. As shown in this figure, on the machining path, the shape change position AW, the workpiece shape influence range A′W, the machining fluid influence range AW ′, and the workpiece shape / working fluid shadow range A′W ′ overlap, the workpiece shape A region where the influence range A′W, the machining fluid influence range AW ′ and the workpiece shape / working fluid shadow range A′W ′ overlap, a region where the machining fluid influence range AW ′ and the workpiece shape / working fluid shadow range A′W ′ overlap, In addition, it can be roughly divided into regions of only the workpiece shape / working fluid shadow range A′W ′. A portion where the machining conditions of FIG. 16 are applied to each of these regions is a portion indicated as “electrical condition, mechanical condition” in the drawing. In addition, in order to clarify the correspondence with the position of the work, this figure also shows a top view of the work with the work shape influence range added.

  Here, the portion represented by the area A is an end portion of the workpiece 101, and the shape name corresponds to “edge”. Therefore, as the processing conditions for this portion, the shape in FIG. 16 is selected from “edges” according to the shape state. It should be noted that since the ratio of suppressing the machining conditions is the same in any region at the “edge”, all the regions A are processed under the same conditions. This is the same for the part represented by the region B and the part represented by the region C.

  The portions represented by the regions C and D are holes 111, and the shape name corresponds to “hole”. Therefore, as the processing conditions for this portion, the shape of FIG. 16 is selected from “holes” according to the shape state. As shown in FIG. 16, the machining conditions are suppressed in a region where the shape change position AW, the workpiece shape influence range A′W, the machining fluid influence range AW ′, and the workpiece shape / working fluid shadow range A′W ′ all overlap. The area where the workpiece shape influence range A'W, machining fluid influence range AW 'and workpiece shape / working fluid shadow range A'W' overlap, and the machining fluid influence range AW 'and workpiece shape / working fluid shadow In the region where the range A′W ′ overlaps, the rate of suppressing the machining condition is the next largest, and in the region of only the workpiece shape / working liquid shadow range A′W ′, the rate of suppressing the machining condition is the smallest. These machining conditions are shown at each position on the machining path in the figure. That is, the processing is performed while suppressing the machining conditions most at the shape change position, and the rate at which the machining conditions are gradually reduced as the distance from the shape change position increases. In the processing of step S95 to step S101 described above, the machining conditions are controlled as shown in FIG. 17, and the electric discharge machining process is executed.

  After or after step S94, the machining progress position acquisition unit 16 acquires the current machining progress position (step S105), and refers to the NC program to determine whether or not the machining is completed (step S106). If the machining has not ended, the process returns to step S92, and the above-described processing is repeatedly executed until the machining path reaches the end point. Further, when the machining process is finished, the electric discharge machining process is finished.

  In the second embodiment, as the machining state, the shape feature information AW, the workpiece shape influence range A′W, the machining fluid influence range AW ′, and the workpiece shape / working fluid influence range A′W ′ are overlapped on the machining path. The machining conditions are changed accordingly, but any one of the ranges can be selected and processed as in the first embodiment.

  According to the second embodiment, the shape feature information AW, the work shape influence, and the intersecting portion between the wire and the 3D shape information of the work to be machined are considered in consideration of the machining shape influence range and the machining liquid influence range, respectively. The range A'W, the machining fluid influence range AW ', and the workpiece shape / working fluid influence range A'W' are obtained, and the machining conditions are changed in accordance with how these ranges overlap. Even when the shape feature changes, there is an effect that the electric discharge machining can be executed under the condition that the wire breakage does not occur. In addition, there is an effect that the processing conditions can be changed step by step near the region where the thickness changes.

  18 to 19 are diagrams for explaining the characteristics of the second embodiment. FIG. 18 is a diagram illustrating an example of the positional relationship between the shape characteristics in the workpiece and the machining path. FIG. It is a figure which shows an example of the positional relationship of a standing vertical wall and a process path. As shown in FIG. 18, in the case of a machining path A that passes near the center of the two holes 111 formed in the workpiece 101 and a machining path B that passes near the ends of the two holes 111, the embodiment Even with 1, it is possible to perform processing without causing wire breakage. However, when machining the vicinity of the end of the hole 111, such as the machining path C passing through the vicinity of the end of the two holes 111, the flow of the machining fluid changes due to the presence of the hole. In the method, since the machining control based on the shape feature cannot be performed, the wire breakage may occur during the machining process. Further, in the machining paths A, B, and C, the shape of the machining path and the change in the flow of the machining liquid associated therewith are different, so that the machining condition control methods are different. On the other hand, according to the second embodiment described above, since the machining conditions are changed based on the shape state on the machining path, the machining conditions suitable for each of the machining paths A to C are also provided. Since the machining process can be executed in this manner, there is an effect that wire breakage does not occur and appropriate machining is performed with minimal reduction in machining speed.

  Also, as shown in FIG. 19, the flow of the machining fluid changes due to the presence of the standing wall 113 even when the machining path is along the standing wall 113 formed on the workpiece 101. In the second embodiment, even in such a case, since the machining conditions are set in consideration of the machining shape influence range in which the presence of the standing wall 113 affects and the wire shape influence range in which the wire shape affects, There is an effect that wire breakage does not occur and proper machining is performed with minimal reduction in machining speed.

  As described above, the electric discharge machining apparatus according to the present invention is useful for the electric discharge machining of a workpiece having a shape change.

It is a block diagram which shows typically the function structure of Embodiment 1 of the electric discharge machining apparatus by this invention. It is a figure which shows an example of processing conditions. It is a flowchart which shows an example of the procedure of the extraction process of the shape information on a process path. It is a perspective view which shows an example of the shape of the workpiece | work used as the object of electric discharge machining. It is a top view of the workpiece | work of FIG. It is a figure which shows the process path | route of the workpiece | work of FIG. It is a figure which shows the plate | board thickness information on the process path | route shown by FIG. It is the figure which added the shape change position to the plate | board thickness information of FIGS. FIG. 7B is a diagram in which a condition change area is further added to FIG. It is a flowchart which shows an example of the procedure of an electrical discharge machining process. It is a block diagram which shows typically the function structure of Embodiment 2 of the electric discharge machining apparatus by this invention. It is a perspective view which shows an example of the shape of a workpiece | work. It is a top view of the workpiece | work shape of FIGS. 10-1. FIG. 10B is a diagram in which a work shape influence range is added to the work shape. It is a figure which shows a process liquid influence range typically. It is a flowchart which shows an example of the procedure of a shape feature extraction process. It is a figure which shows the board thickness information which shows the board thickness change on the process path | route shown by FIGS. 10-2. It is a figure which shows an example of the process path information which added the shape change position, the workpiece shape influence range, the machining fluid influence range, and the workpiece shape and the machining fluid influence range to the plate thickness information. It is a flowchart which shows an example of the procedure of an electrical discharge machining process. It is a figure which shows an example of processing conditions. It is a figure which shows an example of the process path information at the time of processing the workpiece | work of FIG. 10-2. It is a figure which shows an example of the positional relationship of the shape in a workpiece | work, and a process path. It is a figure which shows an example of the positional relationship of the standing wall in a workpiece | work, and a process path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrical discharge machining apparatus 11 Three-dimensional shape information storage part 12 NC program storage part 13 Machining path board thickness information acquisition part 14 Shape feature extraction part 15 Machining path information creation part 16 Machining path information storage part 17 Machining position acquisition part 18 Machining Condition storage unit 19 Machining condition determination unit 20 Machining condition change unit 21 Output / display unit 22 Numerical control unit 23 Control unit 24 Work shape influence range creation unit 25 Machining fluid influence range creation unit 101 Work 111 Hole 112 Step 113 Standing wall

Claims (9)

A wire for electric discharge machining a workpiece to be machined into a predetermined shape;
A nozzle for supplying a machining fluid from the extending direction of the wire toward a machining portion of the wire and the workpiece;
Numerical control means for processing the workpiece using the wire based on a numerical control program;
In an electric discharge machining apparatus comprising:
The shape change position where the plate thickness of the workpiece changes on the machining path defined by the numerical control program and the type of the shape are extracted, and the shape where the change in the plate thickness of the workpiece affects the electric discharge machining process. a machining path information creating means for creating a machining route information set on the machining path range around around the changed position as a condition change area,
Machining progress position acquisition means for acquiring a current machining progress position of the wire in the workpiece during electric discharge machining;
Machining condition storage means for storing machining conditions in the condition change area for each type of shape formed on the workpiece;
When the current machining progress position acquired by the machining progress position acquisition means reaches the condition change area in the machining path information, a machining condition corresponding to the shape type is acquired from the machining condition storage means. Machining condition setting means for setting as new machining conditions;
With
The electrical discharge machining apparatus, wherein the numerical control means executes an electrical discharge machining process based on the machining conditions set by the machining condition setting means. From the outline of the workpiece, a workpiece shape influence range creating means for creating a workpiece shape influence range of a predetermined range in a direction perpendicular to the outline;
A machining fluid influence range creating means for creating a machining fluid influence range of a predetermined range perpendicular to the extending direction of the wire;
Further comprising
The machining path information creation means includes, as the condition change area, a workpiece shape influence range on a machining path that is an intersection of the workpiece shape influence range and the wire, and an intersection of the workpiece contour and the machining fluid influence range. The machining fluid influence range on the machining path, which is a part, and the workpiece shape / working fluid influence range on the machining path, which is the intersection of the workpiece shape influence range and the machining fluid influence range, were determined and set on the machining path. Create machining path information,
The machining condition storage means indicates, for each type of shape formed on the workpiece, a shape change position on the machining path, a workpiece shape influence range, a machining fluid influence range, and a degree of overlap of the workpiece shape / working fluid influence range. Store machining conditions for each shape state,
The machining condition setting means acquires the machining conditions corresponding to the shape state at the current machining progress position acquired by the machining progress position acquisition means from the machining condition storage means, and sets as new machining conditions. The electric discharge machining apparatus according to claim 1.   The machining condition is characterized in that the greater the degree of overlap between the shape change position on the machining path, the workpiece shape influence range, the machining fluid influence range, and the workpiece shape / working fluid influence range, the more the machining condition is suppressed. The electric discharge machining apparatus according to claim 2.   The electrical discharge machining apparatus according to any one of claims 1 to 3, wherein the type of shape formed on the workpiece is any one of a hole shape, a standing wall, and a step.   5. The machining condition stored in the machining condition storage means is any one of a machine condition including a machining speed or a machining fluid amount and an electrical condition including machining energy. Electrical discharge machining apparatus as described in one.   The electric discharge machining apparatus according to claim 1, further comprising an input unit that inputs a machining condition to the machining condition storage unit.   The workpiece for extracting the shape type is a three-dimensional model, and further comprises three-dimensional shape information storage means for holding information on the three-dimensional model and the shape name of the feature portion of each shape. The electric discharge machining apparatus according to any one of the above. A wire for electric discharge machining a workpiece to be machined into a predetermined shape;
A nozzle for supplying a machining fluid from the extending direction of the wire toward a machining portion of the wire with the workpiece;
Machining condition storage means for storing machining conditions for each type of shape formed on the machining path of the workpiece;
Numerical control means for processing the workpiece using the wire based on a numerical control program;
An electric discharge machining method in an electric discharge machining apparatus comprising:
Extract the shape change position and the shape type of the workpiece thickness on the machining path of the numerical control program, and center on the shape change position where the thickness change of the workpiece affects the EDM process and to set on the machining path range around condition change area, and the machining path information generation step of generating a machining path information,
A machining progress position acquisition step of acquiring a current machining progress position of the wire in the workpiece during an electric discharge machining process;
When the current machining progress position acquired in the machining progress position acquisition step reaches the condition change area in the machining path information, the machining condition corresponding to the type of shape is acquired from the machining condition storage means. A machining condition setting step to set as a new machining condition;
The numerical control means, a machining process step of performing an electric discharge machining process based on the machining conditions set by the machining condition setting step ,
An electrical discharge machining method comprising: From the outline of the work, a work shape influence range creating step for creating a work shape influence range of a predetermined range in a direction perpendicular to the outline;
A working fluid influence range creating step for creating a working fluid influence range of a predetermined range perpendicular to the extending direction of the wire;
Further including
In the machining path information creation step, as the condition change area, a workpiece shape influence range on the machining path which is an intersection of the workpiece shape influence range and the wire, and an intersection of the workpiece contour and the machining fluid influence range The machining fluid influence range on the machining path, which is a part, and the workpiece shape / working fluid influence range on the machining path, which is the intersection of the workpiece shape influence range and the machining fluid influence range, were determined and set on the machining path. Create machining path information,
In the machining condition setting step, the shape change position, the workpiece shape influence range, the machining fluid influence range, and the workpiece shape / machining fluid influence range on the machining path at the current machining progression position acquired in the machining progression position acquisition step . 9. The electric discharge machining method according to claim 8, wherein machining conditions corresponding to the shape state indicating the degree of overlap are acquired from the machining condition storage means and set as new machining conditions.

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