JP4498722B2 - Electric discharge machining method and electric discharge machining apparatus - Google Patents

Description

  The present invention relates to an electric discharge machining method and apparatus for performing electric discharge machining while jumping an electrode having a three-dimensional shape with respect to a workpiece, and in particular, according to machining depth and machining shape change as machining proceeds. The present invention relates to an electric discharge machining method and an electric discharge machining apparatus that can perform machining under optimum jump operation conditions.

  In general, the tool electrode and the workpiece are arranged facing each other at a predetermined interval, and a discharge voltage is applied to both electrodes and the workpiece to generate a discharge between the electrodes and the electrode and the workpiece. 2. Description of the Related Art An electric discharge machining apparatus is known in which a workpiece is processed by being relatively moved so as to be processed into a desired shape. In electrical discharge machining, the electrode is gradually lowered as the machining progresses. However, in machining, the tool electrode eliminates servo control, oscillation control, and machining debris. In general, an operation for separating the workpiece (hereinafter referred to as a jump operation) is controlled. The jump operation is set, for example, with the set ascending time, descending time and speed or distance.

  There are already a wide variety of modes for setting and controlling the jump operation. As a typical example, the operator selects and sets the repetition period and stroke (jump amount, that is, the separation distance) of the jump operation. In addition, there is known a mode in which an operator switches as necessary, and there are various types of automation including this.

  For example, as shown in Patent Document 1, a jump condition switching condition table combining a plurality of large and small jump distances and machining time (cycle) at the time of proximity is prepared, and a machining hole associated with the progress of electric discharge machining is prepared. In response to the increase in the depth of machining and the worsening of the machining state in the machining gap due to the passage of machining time, there is a switch that increases the separation distance of jump operation and shortens the proximity machining time at the time of proximity. is there.

  Also, in recent years, the technique of adjusting the jump cycle and jump distance, which is performed by experienced workers based on experience, has been adopted, and the stability and change of the electrical discharge machining state from the voltage, current values and waveform characteristics detected from the electrical discharge machining gap. Calculate the rate and output the jump period increment and the electrode opening distance increment by the jump operation by fuzzy inference from this stability and the rate of change of stability, and change and control the jump period and distance The thing (for example, refer patent document 2) is proposed.

  As described above, in addition to the configuration in which the state of the machining gap is detected and the jump cycle and jump distance are always controlled to the optimum values according to the state, as part of the machining conditions as proposed in Patent Document 3 Some perform jump operation settings. In the electric discharge machining apparatus disclosed in Patent Document 3, a combination of machining information including items related to the shape and material of the machining electrode, the material of the workpiece, the machining depth, and the machined surface roughness, and machining conditions suitable for the combination Is created, and each item of machining information is input, a machining condition suitable for the combination of each item of machining information is selected from the machining condition table of the database. A machining condition including the selected electrical machining condition and a jump condition suitable for the selected electrical machining condition is set by the numerical controller, and the electric discharge machining is performed.

As described above, the conventional jump condition setting method is broadly divided into a method for setting or changing the jump period and the separation distance in response to the state of the machining gap as shown in Patent Documents 1 and 2. And a method in which jump conditions are set in a database as machining conditions, and jump conditions suitable for the machining are selected and set in advance based on information on machining forms, as shown in Patent Document 3 There is.
Japanese Patent Publication No.54-7998 JP-A-6-170645 JP 2001-38530 A

  By the way, the jump operation during electric discharge machining includes the electrode shape and workpiece shape, the set electrical machining conditions, the current machining depth, the machining area, the supply condition of the machining fluid to the machining gap, and the set machining. Depending on the servo control conditions for maintaining the gap, etc., the jump separation distance, machining time or cycle when approaching, the speed of reciprocating movement, especially the feed speed when opening or approaching, and the combination of these values Each value has its own proper value. Therefore, the optimum value adjustment setting is almost difficult, and even if a certain degree of adjustment setting can be made, if the depth of the processing hole, the processing area, the processing shape, etc. change as the processing progresses, The appropriate value of each jump condition value changes.

  This is considered to be a problem if the method of changing and controlling the jump setting according to the state of the machining gap, which corresponds to the former prior art described above, is not problematic. In principle, machining does not proceed unless machining waste is discharged out of the machining hole, and machining is not stable. In other words, in the conventional machining gap state tracking type jump setting control method, after detecting the deterioration of the machining state caused by machining stagnation in the machining hole, the jump operation is controlled to improve the state. Therefore, it cannot be said that the jump setting that can effectively remove the machining waste is performed. In order to avoid abnormal discharge when the machining state deteriorates, other controls such as control for extending the pause width between machining current pulses and control for reducing machining current pulse energy are simultaneously performed. These controls always control the deterioration of the machining state in the direction of reducing the machining amount to improve the machining gap state, so that the machining speed naturally becomes slow.

  In addition, in this jump operation control method, excessive jump operation is inevitably caused in order to try to remove the machining waste by the jump operation after detecting the state in which the machining waste is not properly discharged from the machining gap. Will be done. In addition, even if the accumulated processing waste can be discharged and the processing state is improved, there is a risk that if the product is immediately returned to the original state, it may fall into the same processing state. The time will be shortened. This tendency becomes more prominent as the processing depth increases.

  Also, as in the latter prior art, from the processing information such as the electrode shape and material, the material of the workpiece, the processing depth processing surface roughness, etc., by selecting and setting jump conditions suitable for the processing from the database, It is possible to set a jump operation suitable for a desired machining form. However, there are a wide variety of electrode shapes used for electric discharge machining, and in the case of the latter prior art, the jump operation suitable for the approximate electrode shape is selected and set from the data table. It is possible to set the jump opening distance, machining time or cycle when approaching, reciprocating speed etc. according to the shape, machining depth, machining area etc. that are actually changing Therefore, in actual machining, the conditions on the safe side are selected and set so that arc discharge does not occur during machining, and the electrode / workpiece does not get a shake. For this reason, the average machining speed must inevitably be reduced from the estimated machining speed or the theoretical machining speed.

  As described above, in the conventional technique, the jump operation setting is determined based on the state of the machining gap and the jump operation is changed and controlled, or jump conditions corresponding to the rough machining shape or electrode shape are called from the database. It is used, and it cannot be said that the optimum jump condition corresponding to the actually machined shape that changes every moment as the machining progresses is set.

  The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to make the jump operation during electric discharge machining an actual machining shape, machining depth, which changes with machining progress, or Electric discharge that can shorten machining time by improving machining efficiency by presetting an optimal jump operation according to the machining area, etc., so that machining waste is always discharged well. To provide a machining method and an electric discharge machining apparatus. Furthermore, the object of the present invention is executed within a preset range even if the machining state deteriorates for some reason even though the machining is performed with the jump setting suitable for the electrode shape and the like. It is an object of the present invention to provide an electric discharge machining method and apparatus capable of performing electric discharge machining without changing the jumping operation therein and reducing the machining efficiency as in the conventional apparatus.

  In the present invention, CAD data (electrode solid model data) related to an electrode model designed by a CAD apparatus having a relational database structure is processed by the electrode model using an identification method for identifying the electrode shape from the characteristics related to the shape. Which electrode shape classification (or processing type classification) belongs is identified. Then, obtain the machining cross-sectional area (or machining volume) for each predetermined depth when machining with the electrode model, and set jumps for machining depths prepared for each machining area for multiple electrode shape classifications Based on the database, a jump setting value corresponding to the machining depth is determined from the database corresponding to the obtained machining area. The determined jump setting data is used to perform electric discharge machining while switching the jump setting as the machining progresses, and the set jump setting is changed within a predetermined range. A controllable configuration is added so that it can cope with a worsening of the machining state.

In order to achieve the above object, the method of the present invention is an electrical discharge machining method for performing electrical discharge machining on a workpiece while jumping a three-dimensional shaped engraving electrode. Based on the modeled data of the engraved electrode, it is classified according to the size of the engraved electrode, then according to the processing depth, and further classified according to attribute information indicating a specific process such as gate processing. The electrodes are classified according to the geometric shape of the tip of the engraved electrode, such as the presence or absence of the edge, the number, the shape of the apex, the number, the curved state of the bottom surface, the presence or absence of the side slope, the angle, and the cross-sectional shape. predetermined electrode shape of the shaped carving electrode from features of the electrode shape including the size and the machining depth and the attribute information of the type Carving electrode using identification techniques for identifying the electrode shape and said geometric properties of shape Divided into electrode shape classification A step of obtaining a machining area for each predetermined depth when machining with the engraved electrode, and a jump associated with a machining depth prepared for each machining area for the plurality of electrode shape classifications A database that matches the classified electrode shape classification is selected from the database in which the setting data is stored, and jump setting data corresponding to the calculated processing area for each predetermined depth is obtained to obtain the shape of the engraved electrode. And a step of determining jump settings for each predetermined depth, characterized in that the electric discharge machining method performs machining while switching the jump settings with the progress of machining using the determined jump settings. .

  Preferably, the state of the machining gap is detected, and when the deterioration of the machining gap state is detected, the jump operation condition is changed and controlled so as to shorten the machining time or increase the jump distance within a preset range. It is an electric discharge machining method characterized by performing electric discharge machining.

In order to achieve the above object, according to a third aspect of the present invention, there is provided an electric discharge machining apparatus according to the present invention, wherein the electric discharge machining apparatus is an electric discharge machining apparatus for electric discharge machining of a workpiece while jumping an engraved electrode. Means for capturing CAD data relating to the engraved electrode model, CAD data analyzing means, attribute information indicating a specific process such as the size, processing depth, and gate processing of the engraved electrode, and the presence or absence of an edge on the bottom surface of the engraved electrode A predetermined electrode shape from the characteristics of the electrode shape, including the shape of the tip of the engraved electrode such as the number, the shape of the apex, the number, the curved surface state of the bottom surface, the presence or absence of the inclination of the side surface, the angle, and the cross-sectional shape A storage device in which an identification method for identifying a classification is stored, and an electrode shape for identifying to which electrode shape classification the processing by the engraved electrode of the CAD data belongs using the identification method A different means, a machining area calculation means for obtaining a machining area for each predetermined depth in machining with the engraved electrode shape of the CAD data, and a jump setting for a machining depth corresponding to the machining area for the plurality of electrode shape classifications Jump setting database in which data is stored and jump setting data corresponding to the machining area for each predetermined depth in the identified electrode shape classification, the setting value of the jump operation for each predetermined machining depth Jump setting means for determining and outputting the value, and configured to perform machining while switching the jump setting with the progress of machining based on the set value.

In order to achieve the above object, an electric discharge machining apparatus according to a fourth aspect of the present invention is an electric discharge machining apparatus that performs electric discharge machining of a workpiece while performing a jump operation of a sculpted electrode. Means for capturing CAD data relating to the engraved electrode model, CAD data analyzing means, attribute information indicating a specific process such as the size, processing depth, and gate processing of the engraved electrode, and the presence or absence of an edge on the bottom surface of the engraved electrode A predetermined electrode shape from the characteristics of the electrode shape, including the shape of the tip of the engraved electrode such as the number, the shape of the apex, the number, the curved surface state of the bottom surface, the presence or absence of the inclination of the side surface, the angle, and the cross-sectional shape A storage device in which an identification method for identifying a classification is stored, and an electrode shape for identifying to which electrode shape classification the processing by the engraved electrode of the CAD data belongs using the identification method A different means, a machining area calculation means for obtaining a machining area for each predetermined depth in machining with the engraved electrode shape of the CAD data, and a jump setting for a machining depth corresponding to the machining area for the plurality of electrode shape classifications A jump setting database in which data is stored and jump setting data corresponding to the machining area for each predetermined depth in the identified electrode shape classification are used to determine a setting value for the jump operation for each predetermined depth A jump setting means for outputting, a machining gap detection means for generating an output signal when the machining gap state is detected and the machining state is deteriorated, and the jump operation in response to the output of the machining gap detection means. Setting value changing means for changing the setting value within a predetermined range, and based on the setting value or the changed setting value, as the processing proceeds And a discharge machining apparatus that performs change control while processing the jump motion Te.

  According to the electric discharge machining method of the present invention, it is possible to use the database most suitable for the electrode shape by identifying the electrode shape from the data of the electrode model already designed by the CAD apparatus and identifying the shape classification. In addition, the optimum jump setting value corresponding to the machining depth is determined corresponding to the machining area that changes every moment as the machining progresses. Since an appropriate jumping operation is performed and the machining chip is always well removed, the machining efficiency can be improved. In addition, unlike the conventional jump control, the change control is not performed after the state of the machining gap has deteriorated, so other controls that reduce machining efficiency are extremely rare, and the machining gap state that always provides the best machining efficiency. Electric discharge machining can be performed with In addition, even if the state of the machining gap deteriorates for some reason, it is changed to a jump setting value that enhances the chip exclusion effect within a preset range, so that the machining efficiency is not reduced more than necessary. There exists an effect that it can process.

  In addition, according to the electric discharge machining apparatus of the present invention, there is provided a means for capturing CAD data (solid model data) of an electrode model that has already been prepared for electrode production, and an identification method for identifying the electrode shape from the features related to the electrode shape. An electrode shape identifying means for calling an identification method from a stored storage device and identifying which electrode shape (or shape classification) the processing of the CAD data by the electrode belongs to using the identification method. Thus, the electrode shape is classified more accurately. Further, a processing area calculating means for obtaining a processing area for each predetermined depth in the processing based on the electrode shape of the CAD data is provided, and a change in the processing area for each predetermined depth is accurately calculated. A jump setting database storing jump setting data for a machining depth corresponding to the machining area is prepared for a plurality of electrode shapes, corresponding to machining depth and area change as well as the electrode shape. Since the jump setting is performed accurately, the machining gap is always maintained in the best state, and the control for reducing the machining speed hardly works. Therefore, the most efficient machining is performed and the machining speed is improved.

  Further, when the electric discharge machining apparatus according to the present invention is provided with a machining gap detection device and the jump operation can be changed and controlled within a predetermined range by the output thereof, the machining dust is only collected when the machining gap deteriorates for some reason. Therefore, the jumping operation is not performed on the safe side more than necessary, and the processing efficiency is not lowered as in the conventional case.

FIG. 1 shows the overall configuration of an electric discharge machining apparatus showing the best mode for carrying out the present invention. In the electric discharge machining apparatus of the present invention, the engraved electrode 1 having a three-dimensional shape is attached to an electrode holding member provided at the lower end of the quill 12 constituting the Z-axis machining head unit 10. In order to enable servo operation and jump operation in the Z-axis direction of the engraved electrode 1, the quill 12 is guided in a vertically movable manner by a linear guide device (not shown) provided in the machining head unit 10. A magnet plate 13 in which a plurality of permanent magnets are arranged is attached to two side surfaces of the quill 12 facing each other, and the quill 12 and the magnet plate are integrated to form a mover of the linear motor. The armatures 11 of the two linear motors are fixed to the housing of the machining head 10 so as to be opposed to the respective magnet plates 13 with a small gap from the magnet plate 13. The armature 11 includes the armature 11 and the magnet plate 13. The linear motor is driven and controlled by the linear motor drive unit 14.

  The processing table 3 is provided with a processing tank for storing a processing liquid, and is configured such that positioning control can be performed in the X and Y axis directions by a linear motor (not shown). The workpiece 2 is placed on the processing table 3, and output lines for supplying electric pulse energy from the discharge power supply device 20 are connected to the workpiece 2 and the engraved electrode 1, respectively. Further, the machining gap detector 21 for monitoring the machining state during the electric discharge machining is applied with the average machining voltage of the electric discharge machining, the voltage value or current value of the machining discharge pulse, and the discharge voltage in order to detect the state of the machining gap. A circuit for detecting a discharge delay time from the start of discharge to the occurrence of discharge is provided, and a detection value detected by the machining gap detector 21 or an evaluation signal output by comparing the detection value with an evaluation value is: It is also used for control of servo operation and control of electric discharge machining pulses such as discharge pause time and discharge current reduction control when the machining state deteriorates. Also in the configuration of the present invention, this conventionally used machining gap detector 21 can be used.

  The jump change control unit 22 is a portion corresponding to the jump operation control unit in the conventional electric discharge machine, and sends a jump operation command to the linear motor driving unit 14 based on the set jump operation rising or falling time and jump speed. Output. The jump change control unit 22 according to the present invention has a predetermined length of time (for example, from 10%) during a period in which a signal indicating deterioration of the machining state output from the machining gap detection unit 21 is output. A portion for additional control to shorten the machining time and / or increase the rise time (in the range of about 20%) is added. Such setting is performed under conditions that are more severe than usual, for example, electric discharge machining in a state where the servo voltage is set to be shorter than the normally set discharge pulse pause time or the average machining voltage is lower. The predetermined range can be easily found by verifying a setting that can eliminate the deterioration of the electric discharge machining state by a jump operation in the environment by an experiment or the like.

  Further, as a method of evaluating the machining state, a method of comparing the detected average machining voltage with a reference value to determine that the machining state is deteriorated when the detected value is equal to or less than the reference value, The machining gap state obtained by calculating the theoretical value data of the electrical discharge machining pulse waveform proposed in, according to the machining conditions, and comparing the actual value data and the theoretical value data of the measured actual electrical discharge machining pulse waveform. A method of judging based on the evaluation value can be adopted.

  The electrode shape identification unit 30, the shape identification method storage unit 31, the jump setting unit 32, the jump setting database 33, and the jump setting storage unit 34 are main parts of the present invention that operate together with the CAD data analysis unit 40 and the machining area calculation unit 41. Based on the data of the three-dimensional model of the electrode designed by the CAD device, the machining shape is identified from the feature of the shape, and the jump setting corresponding to the change of the machining area when machining with the electrode of the shape is predetermined. This is a part that performs a series of operations for each depth.

  Further, the CAD data analysis unit 40 takes in the CAD data of the solid model of the sculpted electrode, and provides information for identifying the electrode shape from the CAD data of the electrode model at the request of the electrode shape identification unit 30. The CAD data analysis unit 40 may have a configuration in which unnecessary portions such as a design-related function, a solid model graphic display function, and a drawing creation function are removed from generally available CAD software functions, such as product dimensions and attribute information. Any function that can analyze solid model data including The processing area calculation unit 41 is a part that calculates the cross-sectional area of the electrode for each predetermined distance from the lower end of the electrode model, the processing volume or the electrode surface area from the lower end to the predetermined distance.

 The CAD data analysis unit 40 and the processing area calculation unit 41 are generally commercially available. For example, Solid Works (registered trademark) CAD software manufactured by Solid Works is installed on a hard disk of a personal computer, and OLE (Object Linking Embedding). Create OEL control by using COM or configure to use volume, surface area or cross-sectional area calculation function of solid model that CAD software has as analysis function by using COM (Component Object Model) be able to.

  More preferably, if the above-mentioned CAD software having a relational database structure is used for the CAD data analysis unit 40 of the implementation apparatus of the present invention, the data of the product model designed by the CAD device for product design is stored in gold. CAD that was created in the upstream stage of design, if it is incorporated in a CAD device for mold design or if the device of the present invention is used to design the sculpted electrode from the data of the product model and use the electrode design data as it is Data can be used without complicated design work and input work.

  The HI unit 50 is a part that handles functions necessary for operating the numerical control device. The HI unit 50 acquires electrode position information from the numerical control device and displays the information on the display device 52, or the processing conditions for the electric discharge machine. This is a part having a function of an interface between the operator and the numerical control device such as setting / editing, creation and execution of an NC program. As the input device 51, a keyboard, a flexible disk reader, a CD or DVD-ROM reader, a LAN connection input unit using Ethernet (registered trademark), or the like can be used. The display device 52 displays the 3D model display of the electrodes and the contents of operations performed in the HI unit 50 serving as an interface between the operator and the numerical control device of the electric discharge machine on a CRT or LCD.

  The configuration from the electrode shape identification unit 30 to the display device 52 can use a general personal computer (hereinafter referred to as a personal computer). A portion expressed using a square frame in FIG. 1 represents software as a functional block. The setting values stored in the shape identification technique storage unit 31, the jump setting database 33, and the jump setting storage unit 34 are stored in a storage device such as a hard disk drive provided in a personal computer or a CDROM using a CD-R / RW. A medium can also be used.

The electrode shape identification unit 30 extracts necessary information from the electrode model data taken into the CAD data analysis unit 40 by OLE control or COM. Here, for example, a case where information necessary for an electrode model is extracted from CAD data in which the solid model data is created with a B-rep (Boundary Representations) structure will be described. In the B-rep structure, solid model data is extracted. There are ridges, vertices, and faces as the constituent elements of the, and the structure is such that the ridge line connects two vertices, the face is surrounded by ridge lines, and the solid is surrounded by faces. Based on the rule that “one ridge line is always shared by two surfaces”, the ridge line, the vertex, and the surface are linked to each other. Necessary data is acquired by searching for components such as vertices and faces so as to follow the B-rep structure. In addition, ridge lines, vertices, and surfaces have various parameter information, such as vertex: coordinate value, ridge line: straight line or curve type, line equation coefficient, surface: plane or curved surface type, and surface equation coefficient. It is linked, and from these pieces of information, it can be determined whether it is a curved surface or a flat surface.

  A plurality of electrode shape identification methods are stored in the shape identification method storage unit 31, and information necessary for this identification method is obtained from the CAD data analysis unit 40 using the OLE control prepared in the electrode shape identification unit 30. get. FIG. 2 illustrates some electrode shapes used for sculpting electric discharge machining. What is described together with the reference numerals (a) to (j) is a name representing the type, shape, or characteristics of the processing. As a general feature, (a) is a processing area or a projected area (a shadow area formed when light is applied from above the electrode, and a cross-sectional area of a hole on the surface of the workpiece that is actually exposed to electric discharge machining). The value of the square root of the processing area S is larger than the processing depth L at 25 square millimeters or less. This is an electrode shape often used for core pin processing of connectors.

  (B) is an electrode shape that is elongated and has a conical tip. Then, the processing is performed so that the processing depth L is larger than three times the square root of the processing area, and generally has a shape that is often used for gate hole processing of an injection mold. In particular, when it is determined that the processing is a gate, the gate processing is classified when the maximum conical area of the portion where the electrode is located in the hole of the workpiece is 90% or more.

In the processing with a certain processing area, it is identified from the topology of the tip of the electrode and the electrode dimensions. (C) is a process in which there is a rectangular flat portion on the bottom surface of the electrode, the length (thickness) of the short side of the electrode is about 3 mm or less, and the processing depth is, for example, 5 times the length of the short side. The electrode to be performed is generally called rib processing. In order to identify the electrode as a rib machining electrode, it can be identified from the dimensions of each part of the electrode and the planned machining depth. Therefore, the above-described values may be determined in advance in the identification method. (D) and (e) are shapes having no flat surface on the bottom surface. If the bottom shape is a horizontal semi-cylindrical shape as shown in the figure and occupies about 90% or more of the processed part, it is recognized as a squirrel-shaped shape. Classify. In such a shape, the so-called oscillating direction and oscillating shape of the oscillating machining, which moves the electrode and the workpiece relative to each other at the time of electric discharge machining, also influences. Can be determined.

  The shape of (f) is identified by having a straight edge portion on the bottom surface and whether the side surface is inclined. In (g) and (h), if there is only one point as the edge on the bottom surface and there is a plane on the electrode side surface, it is classified into a pyramid shape, and if there is no plane and the cross section is a circle, it is classified into a cone shape. Further, as in (i), when the bottom surface is a straight edge and inclined on both sides as in (f) and is smaller than a predetermined processing area, the shape is identified and identified as a wedge-shaped electrode. (J) is a shape in which the processing area is extremely large with respect to the processing depth, for example, is identified as a flat and large area shape having a depth of 10,000 square millimeters or more and a depth of 10 mm or less. Classify.

  In this way, the electrode shape is identified and classified based on the shape characteristics such as the electrode shape, that is, the dimensions of each part of the electrode including the processing area, the presence / absence and angle of the side surface, the shape of the bottom surface, and the number of edges existing on the bottom surface. be able to. Such an identification method is stored in the shape identification method storage unit 31, and the electrode shape identification unit 30 takes necessary information from the CAD analysis unit 40 by OLE control, and identifies and classifies the electrode shape according to the identification method. To do. In the CAD data of the electrode model, values such as the electrode material, the number of parts to be processed, and the processing depth are added as attribute information. Similar to these pieces of information, shape classification information can be added at the time of designing. The electrode shape classification may be performed based on the information, but it is also possible that the criteria for identifying the electrode differ depending on the operator. Therefore, the classification given as attribute information and the result determined by the electrode shape identifying unit 30 It is preferable that processing for confirming that the two match is necessary, and if the judgment is different, the difference in identification is displayed on the display device so that confirmation by the operator can be performed.

  The machining area calculation unit 41 obtains a machining area for each predetermined distance (depth) as the machining progresses when electric discharge machining is performed from the designed electrode model. Specifically, the CAD data analysis unit 40 is requested to calculate the cross-sectional area at a predetermined position in the machining direction from the tip of the electrode model, the value of the machining area is obtained for each depth, and the area data is obtained. This is sent to the jump setting unit 32. The interval for calculating the cross-sectional area naturally varies depending on the electrode shape. For shapes whose machining area changes greatly with machining (for example, shapes such as (f), (g), and (h) in FIG. 2), the cross-sectional area is calculated by narrowing the interval. When there is no change in the processing area like the columnar shape of the electrode, the area of only one cross section of the electrode may be obtained. The interval for obtaining the cross-sectional area of the electrode may be determined in advance for the shape classification, and even when the processing area changes greatly, the depth of 0.1 mm is sufficient. The machining area data obtained in this way is sent to the jump setting unit 32.

  Here, the electrode cross-sectional area is used in the same meaning as the processing area. The machining area is the area of the bottom surface of the electrode since discharge starts at the bottom of the electrode at the beginning of machining. At the position where the machining depth has advanced by a predetermined distance h, the electrode cross section at the top surface position of the workpiece is the machining area. Become. This is sometimes called the projected area of the electrode. In addition to determining the above-mentioned processing area from the electrode model data and configuring it as in the present invention, the method of determining and using the processing volume at each depth from the electrode model, and the electrode surface area (side area at each depth) Can be obtained and used as the processing area, or various combinations can be made by appropriately combining them to obtain the processing area.

  The jump setting unit 32 calls the jump setting for the electrode shape corresponding to the shape classification identified by the electrode shape identification unit 30 from the jump setting database 33, and based on the machining area data sent from the machining area calculation unit. The jump operation descent time, jump speed, and jump up time are determined from the jump setting data that matches the machining area. FIG. 3 is a diagram for explaining data stored in the jump setting database 34. The jump setting database 34 stores a plurality of jump setting data that matches the classification identified by the electrode shape identification unit 30, and each shape classification data is further divided by processing area unit. In FIG. 3, jump setting data for three different machining areas are illustrated in the form of a graph.

  Jump operation setting data is stored as data or function of the relationship between machining depth and descent time for a predetermined machining area range, and jump speed data used at that time. Conversion data or a function for obtaining the time for raising the electrode is prepared. For the electrode rise time, since the rise distance changes in relation to the jump speed, a conversion formula is used, but not limited to this, prepare data so that the electrode rise distance can be set with respect to the machining depth If the distance is set, it is set as the separation distance from the current processing position.

  The optimum jump conditions differ depending on the electrode shape. For example, when machining with an electrode shape called rib machining as shown in FIG. 2C, the electric discharge machining time is shortened (the descent time is shortened), The data is such that the speed is high and the rise time is short, and in the case of slitting with a thin plate electrode, for example, an electrode with an electrode thickness of 0.6 mm or less, electric discharge machining is used. When the time is short and the jump speed is set slow and gate hole machining is performed with the electrode shape as shown in FIG. 2B, the electric discharge machining time is shortened, the jump speed is increased, and the jump rise time is increased. When machining with a shape as shown in FIG. 2 (j), it is necessary to set the jump speed slower because the electrode receives a negative pressure from the machining fluid. As described above, the jump setting database 33 stores jump setting data matched to each electrode shape so that the machining depth can be obtained.

  The jump setting unit 32 sets the jump setting acquired from the jump setting database 33 for the machining area for each predetermined depth h sent from the machining area calculation unit 41 according to the progress of the machining depth position. Will be stored. All jump settings for each predetermined depth h from the machining start point to the machining end depth are determined, and all jump operation settings at each depth position are stored in association with the machining depth position. Based on the stored jump settings, the HI unit 50 can create and output an NC machining program for changing the machining depth and jump settings.

  FIG. 4 shows an example of output as an NC program for performing jump change control. The area A in the figure is the header part of the program in which the machining conditions are registered, and C007 to C011 are program codes for calling the machining conditions. The program codes for calling the machining conditions are combined with the machining condition settings. Yes. Where PL is the electrode machining polarity, ON is the discharge pulse on time, OFF is the discharge pause time, IP is the machining current setting, SV is the machining servo voltage setting, S is the servo speed, UP is the jump operation rising time Setting, DN is the fall time setting of the jump operation, and JS is the jump speed setting. The numbers indicate the setting values for each parameter, not actual values. An area B shows an NC program, which is a program for machining while changing the jump setting by sequentially calling machining condition codes as the machining depth increases. By executing this program, it is possible to implement the method of the present invention in which electric discharge machining is performed while changing jump settings in accordance with changes in machining depth and machining shape.

  In the embodiment apparatus shown in FIG. 1, the jump setting stored together with the machining depth in the jump setting storage unit 34 is stored in response to the machining depth information from a numerical controller (not shown). Is reached, a jump setting signal is output to the jump change control unit 22 to change the jump operation. When the electric discharge machining actually proceeds, depth information is sequentially sent from the numerical control device via the HI unit 50, and the jump setting storage unit 34 outputs the jump setting corresponding to the depth to the jump setting changing unit 22, and the electric discharge. A signal indicating the state of the machining gap is sent from the gap detection unit 21 to the jump setting change unit 22. As described above, when the machining state deteriorates and a signal notifying the state deterioration is output to the jump setting changing unit, the jump setting changing unit changes the jump setting within a preset range to make the jump setting on the safe side. A signal to be changed is output to the linear motor drive unit 14 to change the jump operation.

  Next, the operation of the apparatus of the present invention will be described with reference to the flowchart of FIG. An electrode model data file including electrode model data designed by the CAD apparatus and data attached thereto is input from the input 51 and sent to the CAD data analysis unit 40 (step S1). The electrode model data file is opened by the analysis software of the CAD data analysis unit 40, and the electrode shape model and its attribute information are displayed on the display device 52. When the execution of the present invention is requested by an operator's operation, the electrode shape identification unit 30 executes OLE control, thereby causing the CAD data analysis unit 40 to perform electrode characteristics, that is, electrode dimensions and bottom surface shape. Request and extract information (planar area of the electrode bottom surface, presence / absence of edges, number of edges, electrode thickness, curved state of bottom surface, presence / absence and angle of side surface, processing depth information, etc.) (step S2) ).

  The machining area calculation unit 41 requests the CAD data analysis unit 40 to calculate the projected area (electrode cross-sectional area) when machining is actually performed with the captured electrode model for each predetermined machining feed depth h. The value of the electrode cross-sectional area for each predetermined depth is obtained. This value is output to each part at the request of the electrode shape identifying unit 30 and the jump setting unit 32. The predetermined feed depth h for calculating the cross-sectional area is initially set at an interval of about 0.5 to 1 mm, for example. After identifying the electrode shape, it is desirable to shorten the processing time by resetting the machining feed interval in accordance with the electrode shape and recalculating (step S3).

The electrode shape identifying unit 30 identifies the extracted electrode shape data using the shape identifying method stored in the shape identifying method storage unit 31 and classifies the electrode shapes. The electrodes are identified sequentially based on the dimensions and characteristics relating to the electrodes. Specifically, from the maximum value of the cross-sectional area obtained by the processing area calculation unit 41, first, the size of the electrode is determined, and first classified according to whether the electrode cross-sectional area is larger or smaller than a predetermined size, If the processing depth at that time is deeper or shallower than a predetermined value, small processing (processing like the core pin in FIG. 2A) , and FIG. 2B gate processing based on attribute information indicating gate processing, etc. Identify and classify as Furthermore, if the size of the electrode is larger than a predetermined value, it depends on the geometric characteristics of the tip shape of the electrode, that is, whether there is an edge, the shape of the apex (edge point, line or plane), or the bottom plane. The electrode shape is identified based on whether it is a spherical surface or a curved surface with no edges, and the going electrode shape is classified into one of the prepared electrode shapes. (Step S4)

In order to identify and classify an electrode as shown in FIG. 2 (h), for example, a cone having a cone bottom radius of 10 mm and a vertex angle of 60 degrees with a depth of 15 mm, firstly, The maximum value of the processing area is compared with a predetermined area for determining the size. In this case the maximum working area and not a small processing about 235 square millimeters, shows that the vertex is one looking at the characteristics the shape of the tip, then cross shape was judged, the cross-sectional shape Since it is a circle, the electrode is classified as having a conical shape. Other shapes can be similarly identified and classified by the topology of the tip.

  When the electrode shape is identified and classified by the electrode shape identifying unit 30, the information is sent to the jump setting unit 32, and the jump setting unit 32 receives processing area data for each predetermined depth from the processing area calculation unit 41. Call the jump setting data of the classification that matches the electrode shape, and use the data (or function) that matches the value of the processing area (cross-sectional area of the electrode) when actually processed for each predetermined processing feed depth h The jump fall time, jump speed, and jump rise time are determined (step S5). The determined jump setting is sent to and stored in the jump setting storage unit 34 in association with the depth at that time (step S6).

In step S7, if the operator designates to create a program, the data stored in the jump setting storage unit 34 is sent to the HI unit 50, and the processing depth and processing conditions shown in FIG. Program is created. The electrical machining conditions such as the discharge time, the discharge pause time, and the current peak value can be determined based on the machining area calculated by the machining area calculation unit 41. Regarding the method of setting the machining area and the electrical machining conditions, Detailed description will be omitted.

  If machining is selected in step S8, electric discharge machining is started, and if not machining, the process ends (step S8). When processing is selected, the first jump setting stored in the jump setting storage unit 34 is output to the jump setting changing unit. (Step S9). Electric discharge machining is performed while performing a jump operation with the set jump fall time, speed, and rise time. Information on the current machining depth is always sent from the HI unit 51 to the jump setting storage unit 34, and it is determined whether or not the stored jump setting change depth has been reached (step S10). If not, the process proceeds to step S11. If the machining end depth has not been reached, the process returns to step 10 and machining is continued until the change depth is reached. Further, when the processing end depth is reached, the processing ends.

  When it is determined in step 10 that the jump change depth has been reached, the next jump setting is sent from the jump setting storage unit 34 to the jump change control unit 22 and the jump operation is changed. Between steps S8 to S11, the machining gap detection unit 21 always monitors the machining gap, and when the machining gap deteriorates, a signal notifying the deterioration is output to the jump change control unit 22, and from the jump setting storage unit 34 The jump setting is controlled within a preset range, such as shortening the fall time of the jump setting. Of course, it is desirable to provide a separate control for finishing the machining if the state of the machining gap is not improved for a predetermined time or more even if the jump setting in the predetermined range is changed to the safe side.

  INDUSTRIAL APPLICABILITY The present invention can be used for die-sinking electric discharge machining of a die that forms a hole having the same shape as an electrode shape on a workpiece using an electrode for shaping. In addition, if the CAD data of the electrode created by the CAD apparatus is taken in as it is, the optimum jump operation setting for the machining can be determined from the data, and if the value is output as a machining program, the electric discharge machining The present invention can also be applied to a CAM device for creating a machine NC program. By using the main components of the present invention in combination with a CAD apparatus, it can be used in combination with each apparatus other than an electric discharge machine, such as a CADCAM apparatus for electric discharge machining.

It is a schematic diagram which shows the whole structure of the electric discharge machining apparatus of this invention. It is a figure which illustrates the electrode model shape used for die-sinking electric discharge machining. It is a figure explaining the content of the database for the jump setting memorize | stored according to the shape. It is the example output as NC program which performs change control of jump . It is an operation | movement flowchart figure explaining operation | movement of the electric discharge machining apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shape electrode 2 Work piece 3 Processing table 10 Processing head part 11 Armature 12 Quill 13 Magnet plate 14 Linear motor drive part 20 Discharge power supply device 21 Process gap detection part 22 Jump change control part 30 Electrode shape identification part 31 Shape identification Method storage unit 32 Jump setting unit 33 Jump setting database 34 Jump setting storage unit 40 CAD data analysis unit 41 Processing area calculation unit 50 HI unit 51 Input unit 52 Display unit

Claims (4)

In the electric discharge machining method for electric discharge machining of a workpiece while jumping the three-dimensional shaped electrode, it is classified according to the size of the engraved electrode based on the model data of the electrode designed by the CAD device. Next, it classifies by processing depth and classifies by attribute information indicating a specific processing such as gate processing. Further, the presence / absence and number of edges on the bottom surface of the engraved electrode, the shape and number of vertices, the curved surface state and side surface of the bottom surface The shape of the engraved electrode and the processing depth are determined using an electrode shape identification method that identifies the electrode shape by classifying it according to the geometrical shape of the tip of the engraved electrode, such as the presence or absence, the angle, and the cross-sectional shape of the electrode. a step of Sato classified into the attribute information and the geometric characteristics and the electrode shape the shaped carving electrode of electrode shape a predetermined electrode shape classified features for containing a predetermined time of performing the processing by said shaped carving electrode Every depth A database that matches the classified electrode shape classification from a database that stores the jump setting data associated with the machining depth prepared for each machining area with respect to the plurality of electrode shape classifications, and a step of obtaining a machining area Selecting jump setting data corresponding to the determined processing area for each predetermined depth and determining jump setting for each predetermined depth in the engraved electrode, Electric discharge machining method that uses the jump setting to change the jump setting as the machining progresses.   2. The electric discharge machining method according to claim 1, wherein the state of the machining gap is detected, and when a worsening of the machining gap state is detected, a jump operation is performed so as to shorten the machining time or increase the jump distance within a preset range. An electric discharge machining method for performing electric discharge machining while changing and controlling conditions. In an electric discharge machining apparatus for performing electric discharge machining on a workpiece while causing a jumping operation of a sculpting electrode, means for capturing CAD data relating to the sculpting electrode model designed by the CAD apparatus, CAD data analysis means, Attribute information indicating specific processing such as size, processing depth, gate processing, the presence / absence and number of edges on the bottom surface of the engraved electrode, the shape and number of vertices, the curved state of the bottom surface, the presence / absence of inclination of the side surface, and the angle A storage device storing an identification method for identifying a predetermined electrode shape classification from features relating to the electrode shape including a geometrical characteristic of the tip of the engraved electrode such as a cross-sectional shape; and Electrode shape identifying means for identifying to which electrode shape classification the processing by the sculpting electrode of CAD data belongs, and a predetermined depth in processing by the sculpting electrode shape of the CAD data Machining area calculation means for obtaining a machining area, a jump setting database storing jump setting data for a machining depth corresponding to a machining area for the plurality of electrode shape classifications, and the identified electrode shape classification Jump setting means for determining and outputting a set value of a jump operation for each predetermined depth using jump setting data corresponding to the machining area for each predetermined depth in the above, and based on the set value An electrical discharge machining apparatus characterized in that machining is performed while changing jump settings as machining progresses. In an electric discharge machining apparatus for performing electric discharge machining on a workpiece while causing a jumping operation of a sculpting electrode, means for capturing CAD data relating to the sculpting electrode model designed by the CAD apparatus, CAD data analysis means, Attribute information indicating specific processing such as size, processing depth, gate processing, the presence / absence and number of edges on the bottom surface of the engraved electrode, the shape and number of vertices, the curved state of the bottom surface, the presence / absence of inclination of the side surface, and the angle A storage device storing an identification method for identifying a predetermined electrode shape classification from features relating to the electrode shape including a geometrical characteristic of the tip of the engraved electrode such as a cross-sectional shape; and Electrode shape identifying means for identifying to which electrode shape classification the processing by the sculpting electrode of CAD data belongs, and a predetermined depth in processing by the sculpting electrode shape of the CAD data Machining area calculation means for obtaining a machining area, a jump setting database storing jump setting data for a machining depth corresponding to a machining area for the plurality of electrode shape classifications, and the identified electrode shape classification Jump setting means for determining and outputting a set value of a jump operation for each predetermined depth using jump setting data corresponding to the machining area for each predetermined depth in the machining state by detecting the state of the machining gap Machining gap detecting means for generating an output signal when the deterioration is worsened, and setting value changing means for changing the setting value of the jump operation within a predetermined range in response to the output of the machining gap detecting means. An electric discharge machining apparatus that performs machining while changing and controlling a jump operation as machining progresses based on the set value or the changed set value.

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