A method and device for automatic online measurement and compensation of wire-cut electric discharge machining

Abstract

The present invention discloses a method and device for wire-cut electric discharge machining (WEM) with automatic online measurement and compensation. The method comprises: obtaining trajectory data of an electrode wire and basic machining parameters of a workpiece in a measurement system, wherein the basic machining parameters include a target machining shape; controlling the measurement system based on the trajectory data and the basic machining parameters, operating the electrode wire so that contact measurement is performed between the electrode wire and the workpiece; obtaining a contact point on the workpiece when the electrode wire contacts the workpiece, and obtaining position information of the target point based on the position information of the contact point; performing an error comparison between the actual machining shape of the workpiece obtained by fitting and the target machining shape, and determining whether the error data meets the conditions of the preset machining accuracy requirements. If so, the workpiece machining measurement is completed. The present invention can fit the actual position shape of the workpiece through numerical control system data processing, perform accuracy compensation judgment and design, and ultimately achieve the goal of automated machining and reduce production costs.

Description

Technical Field

[0001] The present invention relates to the technical field of special processing, and in particular to an electric spark wire cutting processing method and device with automatic online measurement and compensation. Background Art

[0002] Wire EDM is a process of machining parts using the discharge principle of electric sparks. Figure 1 As shown, the workpiece is connected to the positive terminal of a pulse power supply, and a molybdenum or copper wire is used as the cutting wire. This wire is connected to the negative terminal of the high-frequency pulse power supply as the tool electrode, and spark discharge is used to cut the workpiece. As a specialty machining technique, wire EDM (Electro-Discharge Machining) breaks free from the limitations of traditional mechanical force and energy and can process materials of any hardness, strength, or brittleness. Due to its strong adaptability, high precision, and low cost, this technology holds a significant position in the machining field and is widely used in various industries, including automotive, machine tool manufacturing, and aerospace. Figure 2 The current wire EDM process is demonstrated. The need to remove the workpiece for measurement, error compensation, trajectory planning, and re-clamping prolongs the machining process and impacts efficiency. Furthermore, re-clamping is closely tied to machining accuracy, placing high demands on the operator and leading to unavoidable errors. Summary of the Invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, the present invention aims to address the existing issues of reduced machining efficiency and precision caused by removing, measuring, and re-clamping. A wire EDM method with automatic online measurement and compensation is proposed. This approach shortens machining steps, saves manpower and resources, and improves machining precision and efficiency.

[0005] Another object of the present invention is to provide an electric spark wire cutting machining device with automatic online measurement and compensation.

[0006] To achieve the above-mentioned object, the present invention provides, on one hand, a wire-cut electric discharge machining method with automatic online measurement and compensation, comprising:

[0007] Acquiring trajectory data of the electrode wire and basic processing parameters of the workpiece in the measurement system, wherein the basic processing parameters include a target processing shape;

[0008] controlling the measurement system based on the trajectory data and the basic machining parameters to operate the wire electrode so as to perform contact measurement between the wire electrode and the workpiece;

[0009] When the electrode wire contacts the workpiece, a contact point on the workpiece is obtained, and position information of the target point is obtained based on position information of the contact point;

[0010] The actual machining shape of the workpiece obtained by fitting the position information of the target point is compared with the target machining shape to obtain error data, and it is determined whether the error data meets the preset machining accuracy requirements. If so, the workpiece machining measurement is completed.

[0011] In addition, the automatic online measurement and compensation wire-cut electric discharge machining method according to the above embodiment of the present invention may also have the following additional technical features:

[0012] Furthermore, in one embodiment of the present invention, the measurement procedure in the measurement system includes: planning of trajectory data and selection of basic processing parameters, and judging whether the error data meets the conditions of the preset processing accuracy requirements. If not, a new round of trajectory data planning and selection of basic processing parameters is performed based on the error data and the relative position data of the electrode wire and the workpiece.

[0013] Furthermore, in one embodiment of the present invention, the contact point on the workpiece is obtained when the electrode wire contacts the workpiece, and the position information of the target point is obtained based on the position information of the contact point, including: when the electrode wire contacts the workpiece, a closed circuit formed by the power supply, the electrode wire and the workpiece is obtained, and the position information of the electrode wire is obtained based on the current in the closed circuit and the feedback information of the machine tool motion system; the position information of the contact point is obtained based on the potential difference method and the electrode wire position information, and multiple target points with a preset density are measured based on the position information of the contact point to obtain the position information of the target point.

[0014] Furthermore, in one embodiment of the present invention, after obtaining the location information of the target point, the method further includes: acquiring a set of location information points obtained by measurement.

[0015] Furthermore, in one embodiment of the present invention, the actual processing shape of the workpiece obtained by fitting the position information of the target point is compared with the target processing shape to obtain error data, including: performing data fitting on the position information point set to obtain a fitting curve, performing image processing on the fitting curve and the target processing shape to obtain an image error; or, determining the key points of the target processing shape based on the position information point set, and using the errors of the discrete corresponding key points as discrete error amounts based on the key point determination results.

[0016] To achieve the above-mentioned object, the present invention further provides an automatic online measurement and compensation wire-cut electric discharge machining device, comprising:

[0017] A data acquisition module, configured to acquire trajectory data of the electrode wire and basic processing parameters of the workpiece in the measurement system, wherein the basic processing parameters include a target processing shape;

[0018] a data measurement module, configured to control the measurement system based on the trajectory data and the basic machining parameters, and operate the electrode wire so as to perform contact measurement between the electrode wire and the workpiece;

[0019] a position acquisition module, configured to obtain a contact point on the workpiece when the electrode wire contacts the workpiece, and obtain position information of the target point based on the position information of the contact point;

[0020] The comparison and judgment module is used to compare the error between the actual processing shape of the workpiece obtained by fitting the position information of the target point and the target processing shape, obtain error data, and judge whether the error data meets the preset processing accuracy requirements. If so, the workpiece processing measurement is completed.

[0021] The embodiments of the present invention provide a method and apparatus for wire EDM machining with automatic online measurement and compensation. These methods include automatic online measurement of machined shapes and precision compensation using this technology. These methods can shorten the machining process, save manpower and resources, and improve machining efficiency and precision.

[0022] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0024] Figure 1 This is the existing wire EDM schematic diagram;

[0025] Figure 2 This is the existing wire EDM process flow chart;

[0026] Figure 3 Flowchart of a wire-cut electric discharge machining method for automatic online measurement and compensation according to an embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of a processing process according to an embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of a measurement process according to an embodiment of the present invention;

[0029] Figure 6is a schematic diagram of contact measurement according to an embodiment of the present invention;

[0030] Figure 7 is a flowchart of an actual process applied to wire electric discharge cutting according to an embodiment of the present invention;

[0031] Figure 8 Schematic diagram of the structure of an electric spark wire cutting machining device with automatic online measurement and compensation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0033] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0034] The following describes a wire-cut electric discharge machining method and apparatus with automatic online measurement and compensation according to an embodiment of the present invention with reference to the accompanying drawings.

[0035] Figure 3 The present invention is a flowchart of an automatic online measurement and compensation wire-cut electric discharge machining method according to an embodiment of the present invention.

[0036] like Figure 3 As shown, the method includes but is not limited to the following steps:

[0037] S1, obtaining trajectory data of the electrode wire and basic processing parameters of the workpiece in the measurement system, wherein the basic processing parameters include a target processing shape;

[0038] S2, controls the measurement system based on the trajectory data and basic processing parameters, and operates the electrode wire so that contact measurement is performed between the electrode wire and the workpiece;

[0039] S3, when the electrode wire contacts the workpiece, a contact point on the workpiece is obtained, and position information of the target point is obtained based on the position information of the contact point;

[0040] S4, performing an error comparison between the actual machining shape of the workpiece obtained by fitting the position information of the target point and the target machining shape to obtain error data, and determining whether the error data meets the preset machining accuracy requirements. If so, the workpiece machining measurement is completed.

[0041] Specifically, Figure 4 The figure shows the wire cutting process of electric spark wire cutting electrode. Figure 4 In (1. Etched area, 2. Electrode wire processing track, 3. Workpiece edge), after each cut, the electrode wire cutting track will leave a gap, which is also the result of material erosion. According to the path information of the previous trajectory planning and the designed processing parameters, the CNC system performs a second trajectory planning, the purpose is to make the electrode wire slightly contact with the workpiece at the target point position, so as to measure the position information. The planned measurement path is as follows Figure 5 As shown, Figure 5 (1. Erosion area, 2. Electrode wire running direction, 3. Workpiece edge, 4. Electrode wire measurement key point trajectory). The measurement principle is: a weak voltage is applied to the electrode wire and the workpiece, such as Figure 6 When the electrode wire touches the workpiece, Figure 6 In the diagram (1. Wire electrode, 2. Workpiece, 3. Contact area), the power supply, wire electrode, and workpiece form a closed circuit, generating a weak current. Feedback from the machine tool's motion system provides the wire electrode position. The potential difference method further determines the contact point on the wire electrode, which is the actual position of the target point. The CNC system automatically records and annotates this position. Subsequently, multiple target point measurements are performed at an appropriate density to determine the target point's position, which is then automatically recorded and annotated by the CNC system.

[0042] After the measurement process is completed, the CNC system can automatically obtain the measured position information point set. The workpiece shape can be obtained through data fitting.

[0043] The measurement method of the present invention overcomes the limitations of existing measurement methods. It eliminates the need to remove the workpiece for measurement. Instead, it utilizes the electrode wire used in wire cutting to automatically measure the workpiece's dimensions and shape directly at the workpiece clamping location. This shortens the processing steps, saves manpower and material resources, improves processing efficiency, and avoids the accuracy errors caused by lengthy non-automated steps.

[0044] Furthermore, after the automatic online measurement is completed, the CNC system records the measured position information points. Next, the actual machining results are compared with the required dimensions and shape, the error is calculated, and the accuracy requirements are checked. If the error meets the machining accuracy requirements, no accuracy compensation is required; if the error does not meet the machining accuracy requirements, accuracy compensation is required.

[0045] For example, two methods can be used to calculate the error. The first is to perform data fitting on the position information point set recorded in the CNC system to obtain a fitting curve, which is the actual processing size and shape. The image is then compared with the required size and shape to obtain the overall image error. Then, based on the accuracy requirements, the optimal compensation amount is obtained using data processing methods such as the least squares method. The second method is to directly determine the key points of the original required size and shape based on the measured position information point set, and use the errors of the discrete corresponding key points as the discrete error amount. Then, the optimal compensation amount is obtained through data processing methods such as the least squares method. Of the two methods, the former can better reflect the actual overall processing situation because it has an overall data fitting process, but the data processing process is complicated and may introduce unnecessary errors. The latter can simplify the data processing steps and reduce unnecessary errors because it uses the original measurement data points.

[0046] This error data is used as the new processing requirement, and combined with the relative position of the electrode wire and the workpiece, a new round of trajectory planning and parameter setting is carried out.

[0047] The method for performing precision compensation based on automatic online measurement results in the embodiments of the present invention overcomes the limitations of existing precision compensation technologies. It eliminates the need for manual input of measured dimensional and shape data into the CNC system, nor does it require manual error and compensation calculations. Instead, the dimensional and shape data obtained through automatic online measurement technology is directly transmitted to the CNC system, where it is automatically compared with the required dimensional and shape data, errors are calculated, and the next step of precision compensation processing is automatically determined, thus achieving truly automatic processing. This method can shorten processing steps, reduce operational difficulty, improve processing efficiency, and avoid precision errors caused by lengthy non-automated steps.

[0048] As an example, the present invention is applied to the actual processing steps of wire electric discharge cutting, such as Figure 7 As shown, the whole process can be divided into three main steps, wherein the third step is the key step of the present invention.

[0049] The first step is manual clamping.

[0050] The second step is to automatically plan the trajectory and set the parameters through the CNC program according to the required processing shape and the basic parameters of the machine tool, and then perform discharge machining after all preparations are completed.

[0051] The third step is to perform the first automatic online measurement. Using the trajectory planning results from the previous step and combined with the machining parameters selected in the previous step, the CNC program automatically generates a measurement program. This measurement program includes the electrode wire trajectory planning and basic control parameters. The measurement program controls the motion system to manipulate the electrode wire, enabling contact measurement between the electrode wire and the workpiece. When the electrode wire contacts the workpiece, the circuit is connected. The point of contact between the electrode wire and the workpiece is the point to be measured on the workpiece selected by the measurement program. The specific location of the contact point is obtained through the potential difference method, and the data information is automatically recorded in the CNC program.

[0052] Using the position information obtained through automated online measurement, the actual workpiece shape is fitted and compared against the desired shape to obtain error data. If the error meets the machining accuracy requirements, subsequent machining processes such as cutting and removal are carried out, and machining is complete. If the error does not meet the machining accuracy requirements, accuracy compensation is performed. This error data is used as the new machining requirement, combined with the relative position of the wire electrode and workpiece, to conduct a new round of trajectory planning and machining parameter selection.

[0053] It should be noted that in the process of finishing, in order to ensure the processing accuracy, it is necessary to minimize the number of processing times, thereby reducing the additional errors caused by factors such as the repeated positioning accuracy of the equipment, thereby improving the processing speed while ensuring the processing accuracy.

[0054] The wire EDM method with automatic online measurement and compensation according to the present invention proposes automatic online measurement of the processed shape and precision compensation using this technology. This automated online measurement and precision compensation can shorten the machining process, save manpower and resources, and improve machining efficiency and precision.

[0055] In order to implement the above embodiment, Figure 8 As shown, this embodiment also provides an automatic online measurement and compensation wire-cut electric discharge machining device 10 , which includes a data acquisition module 100 , a data measurement module 200 , a position acquisition module 300 and a comparison and judgment module 400 .

[0056] The data acquisition module 100 is used to acquire the trajectory data of the electrode wire and the basic processing parameters of the workpiece in the measurement system, wherein the basic processing parameters include the target processing shape;

[0057] a data measurement module 200 for controlling a measurement system based on the trajectory data and the basic machining parameters, and operating the electrode wire so as to perform contact measurement between the electrode wire and the workpiece;

[0058] A position acquisition module 300 is used to obtain a contact point on the workpiece when the electrode wire contacts the workpiece, and obtain position information of the target point based on the position information of the contact point;

[0059] The comparison and judgment module 400 is used to compare the actual processing shape of the workpiece obtained by fitting the position information of the target point with the target processing shape to obtain error data, and judge whether the error data meets the preset processing accuracy requirements. If so, the workpiece processing measurement is completed.

[0060] Furthermore, the measurement procedure in the above-mentioned measurement system includes: planning of trajectory data and selection of basic processing parameters. The above-mentioned comparison and judgment module 400 is also used to:

[0061] If the judgment is not satisfied, a new round of trajectory data planning and basic processing parameters selection will be carried out based on the error data and the relative position data of the electrode wire and the workpiece.

[0062] Furthermore, the location acquisition module 300 is further configured to:

[0063] When the wire electrode contacts the workpiece, a closed circuit is formed by the power supply, the wire electrode, and the workpiece. Based on the current in the closed circuit and the feedback information from the machine tool motion system, the wire electrode position information is obtained.

[0064] The position information of the contact point is obtained based on the potential difference method and the electrode wire position information. Based on the position information of the contact point, multiple target points with a preset density are measured to obtain the position information of the target point.

[0065] Furthermore, the above device 10 further includes:

[0066] The point set acquisition module is used to obtain the measured position information point set.

[0067] Furthermore, the comparison and judgment module 400 is further configured to:

[0068] Perform data fitting on the position information point set to obtain a fitting curve, perform image processing on the fitting curve and the target processing shape to obtain an image error;

[0069] Alternatively, the target processing shape is subjected to key point determination based on the position information point set, and the errors of the discrete corresponding key points are used as the discrete error amount according to the key point determination result.

[0070] The automatic online measurement and compensation wire EDM apparatus according to the present invention proposes automatic online measurement of the processed shape and precision compensation using this technology. This automated online measurement and precision compensation can shorten the machining process, save manpower and resources, and improve machining efficiency and precision.

[0071] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

Claims

1. A wire-cut electric discharge machining method with automatic online measurement and compensation, characterized in that: The following steps are involved: Acquiring trajectory data of the electrode wire and basic processing parameters of the workpiece in the measurement system, wherein the basic processing parameters include a target processing shape; controlling the measurement system based on the trajectory data and the basic machining parameters to operate the wire electrode so as to perform contact measurement between the wire electrode and the workpiece; When the wire electrode contacts the workpiece, a contact point on the workpiece is obtained, and based on the position information of the contact point, the position information of the target point is obtained. The position information is obtained by performing a second trajectory planning based on the previously planned path information and the designed processing parameters through the CNC system, so that the wire electrode makes slight contact with the workpiece at the target point position, and the position information is measured. Comparing the error between the actual machining shape of the workpiece obtained by fitting the position information of the target point and the target machining shape to obtain error data, and determining whether the error data meets the preset machining accuracy requirement. If so, completing the workpiece machining measurement; The measurement program in the measurement system includes: planning trajectory data and selecting basic processing parameters, judging whether the error data meets the preset processing accuracy requirements, and if not, performing a new round of trajectory data planning and basic processing parameter selection based on the error data and the relative position data of the electrode wire and the workpiece; The step of obtaining a contact point on the workpiece when the wire electrode contacts the workpiece, and obtaining position information of the target point based on position information of the contact point, includes: When the wire electrode contacts the workpiece, a closed circuit is formed by the power supply, the wire electrode, and the workpiece, and wire electrode position information is obtained based on the current in the closed circuit and feedback information from the machine tool motion system. Obtaining position information of the contact point based on a potential difference method and the electrode wire position information, and performing measurement of a plurality of target points of a preset density based on the position information of the contact point to obtain position information of the target point; After obtaining the location information of the target point, the method further includes: Obtaining a set of measured location information points; The actual machining shape of the workpiece obtained by fitting the position information of the target point is compared with the target machining shape to obtain error data, including: Performing data fitting on the position information point set to obtain a fitting curve, and performing image processing on the fitting curve and the target processing shape to obtain an image error; Alternatively, the target processed shape is subjected to key point determination based on the position information point set, and the errors of the discrete corresponding key points are used as the discrete error amount according to the key point determination result.

2. An automatic online measurement and compensation electric spark wire cutting device, characterized in that: The following steps are involved: A data acquisition module, configured to acquire trajectory data of the electrode wire and basic processing parameters of the workpiece in the measurement system, wherein the basic processing parameters include a target processing shape; a data measurement module, configured to control the measurement system based on the trajectory data and the basic machining parameters, and operate the electrode wire so as to perform contact measurement between the electrode wire and the workpiece; A position acquisition module is used to obtain the contact point on the workpiece when the wire electrode contacts the workpiece, and obtain the position information of the target point based on the position information of the contact point. The position information is obtained by performing a second trajectory planning through the CNC system based on the path information and the designed processing parameters of the previous trajectory planning, so that the wire electrode makes slight contact with the workpiece at the target point position, and the position information is measured; a comparison and judgment module, configured to compare the error between the actual machining shape of the workpiece obtained by fitting the position information of the target point and the target machining shape, obtain error data, and judge whether the error data meets the preset machining accuracy requirement. If so, the workpiece machining measurement is completed; The measurement program in the measurement system includes: planning of trajectory data and selection of basic processing parameters. The comparison and judgment module is also used to: If the conditions are not met, a new round of trajectory data planning and basic machining parameter selection is performed based on the error data and the relative position data between the electrode wire and the workpiece; The location acquisition module is further used to: When the wire electrode contacts the workpiece, a closed circuit is formed by the power supply, the wire electrode, and the workpiece, and wire electrode position information is obtained based on the current in the closed circuit and feedback information from the machine tool motion system. Obtaining position information of the contact point based on a potential difference method and the electrode wire position information, and performing measurement of a plurality of target points of a preset density based on the position information of the contact point to obtain position information of the target point; The device further comprises: Point set acquisition module, used to obtain the measured position information point set; The comparison and judgment module is further used to: Performing data fitting on the position information point set to obtain a fitting curve, and performing image processing on the fitting curve and the target processing shape to obtain an image error; Alternatively, the target processed shape is subjected to key point determination based on the position information point set, and the errors of the discrete corresponding key points are used as the discrete error amount according to the key point determination result.

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