A tool path calculation method and a blisk machining method

Abstract

A tool path calculation method and a blisk machining method, the tool path calculation method is used for machining of a tool to a workpiece, and the tool path calculation method comprises: obtaining a machining path curve of the workpiece; obtaining a dynamic drive of the tool, under the drive of the dynamic drive, a tool movement path of the tool approximates to the machining path curve; and obtaining a tool path, under the drive of the dynamic drive, the tool movement path is the tool path. The tool path calculation method firstly plans a machining path curve, i.e. an ideal machining path, and then makes the tool movement path of the tool approximate to the machining path curve through the dynamic drive to obtain the tool path.

Description

Technical Field

[0001] This invention relates to the field of machining, specifically to a tool trajectory calculation method and an integral bladed disk machining method. Background Technology

[0002] Forming tools have the characteristic of removing material simultaneously in multiple vector directions. When faced with challenges such as narrow machining space and continuous twisting of the machining surface, the use of forming tools can effectively shorten the machining cycle and reduce machining costs. However, existing CAM (Computer-Aided Manufacturing) engineering software cannot simulate and calculate its tool path. Summary of the Invention

[0003] This invention provides a tool trajectory calculation method and an integral bladed disk machining method to improve the situation where tool trajectories cannot be calculated.

[0004] In a first aspect, the present invention provides a tool trajectory calculation method. According to an embodiment of the present invention, the tool trajectory calculation method is used for machining a workpiece with a tool, and the tool trajectory calculation method includes:

[0005] Obtain the machining path curve of the workpiece;

[0006] The dynamic drive of the cutting tool is obtained, and under the drive of the dynamic drive, the tool motion trajectory of the cutting tool approximates the machining path curve;

[0007] The tool path is obtained, and under the drive of the dynamic drive, the tool motion trajectory is the tool path.

[0008] In one or more embodiments, the processing path curve is obtained through topology operations.

[0009] In one or more embodiments, the topology calculation includes manual topology.

[0010] In one or more embodiments, the dynamic drive is a scalar force, and the tool movement trajectory of the cutting tool approximates the machining path curve under the drive of the scalar force.

[0011] In one or more embodiments, obtaining the scalar force includes:

[0012] Define the cutting point of the tool and constrain the degree of freedom of the cutting point on the machining path curve;

[0013] Define the cutting point of the workpiece, wherein the cutting point is on the machining path curve;

[0014] Define the scalar force, define the cutting point as the point of application of the scalar force, define the point being cut as the point of application of the scalar force, define the magnitude of the scalar force as negative, define the duration of action of the scalar force, and define the point of application and the duration of action such that, driven by the scalar force, the tool movement trajectory at the point of application approximates the machining path curve.

[0015] Secondly, the present invention provides a method for manufacturing an integral bladed disk. According to an embodiment of the present invention, the method for manufacturing an integral bladed disk includes:

[0016] The integral bladed disk is machined using forming tools;

[0017] The tool path of the forming tool is obtained by the tool path calculation method described above.

[0018] In one or more embodiments, the integral bladed disk processing method further includes:

[0019] Based on the tool path and the machine tool motion chain, the machine tool motion trajectory is obtained.

[0020] In one or more embodiments, the machine tool motion trajectory is obtained through motion simulation.

[0021] In one or more embodiments, the integral bladed disk processing method further includes:

[0022] Based on the machine tool's motion trajectory, machine tool motion control commands are obtained.

[0023] The embodiments of the present invention possess at least one of the following beneficial effects:

[0024] The tool path calculation method first plans the machining path curve, that is, plans the ideal machining trajectory, and then uses dynamics to make the tool's motion trajectory approximate the machining path curve, thus opening up a technical route for obtaining tool trajectories using forming tools. Attached Figure Description

[0025] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0026] Figure 1 This is a flowchart illustrating the tool trajectory calculation method.

[0027] Figure 2 A flowchart illustrating the manufacturing process of an integral bladed disk;

[0028] Figure 3 This is a flowchart illustrating the manufacturing process of an integral bladed disk. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0030] It should be noted that the accompanying drawings are for illustrative purposes only and are not drawn in the order of execution of the steps, and should not be used as a limitation on the actual scope of protection of the present invention.

[0031] The machining space of integral bladed disks is narrow, and the machining surface is continuously twisted. Using traditional tools for machining results in large cutting forces, easy blade deformation, easy interference between the tool and the workpiece, and severe wear. Furthermore, due to the limitation of tool size, precise machining is not possible, requiring the purchase of a large number of custom tools. In order to meet the requirements of tool accessibility and reduce workpiece deformation, repeated calculations and iterations are required. The iteration process involves the adjustment of tooling fixtures and machining parameters. Once the solution is determined, it is difficult to optimize and improve it. The machining cycle is long, the repeatability is low, and the machining cost is high.

[0032] Forming tools are non-standard or contouring tools designed for complex machining areas. They have the characteristic of removing material simultaneously in multiple vector directions. Using forming tools with multi-vector machining capabilities to machine integral impellers can significantly reduce the number of tool changes, effectively shorten the machining cycle, and reduce machining costs.

[0033] However, existing CAM (Computer-Aided Manufacturing) engineering software cannot simulate and calculate the tool path for multi-point machining of forming tools. From an algorithmic perspective, existing CAM engineering software can only plan the machining path in a single vector direction. Taking UG (Unigraphics NX) as an example, when performing CAM programming, the tool axis direction needs to be defined. However, the tool axis direction options are based on existing, traditional standard tools, so only one tool axis vector direction can be specified. Then, UG plans the tool path based on the selected tool axis vector direction. Therefore, regardless of whether it is turning, milling, or blue arc EDM, at any given moment during machining, only the material removal trajectory of a single cutting point of a traditional tool in a fixed direction can be calculated. In addition, complex and twisted surfaces with narrow machining spaces will trigger a large number of interference alarms in the CAM engineering software, greatly increasing the simulation calculation time and machining costs.

[0034] The tool path calculation method is used for machining a workpiece using a cutting tool. The following description uses the machining of an integral impeller using a forming tool as an example, where the cutting tool is a forming tool and the workpiece is an integral impeller. In one or more other embodiments, the cutting tool is a different type of tool, and the workpiece is a different type of workpiece.

[0035] Figure 1 The flowchart of the toolpath calculation method is shown. For example... Figure 1 As shown, the tool path calculation method includes step S1, obtaining the machining path curve of the integral bladed disk. The machining path curve is an ideal machining trajectory. The machining path curve of the blades on the integral bladed disk is located on the blade surface. The forming tool moves along the machining path curve to machine the target blade. The "blade surface" where the machining path curve is located is the surface of the target blade obtained through machining. In this way, during the machining process, the tip of the forming tool can remove material according to the machining path curve. Exemplarily, the machining path curve is obtained through topology calculation. Exemplarily, the topology calculation includes manual topology, which manually plans to avoid errors caused by automatically generating machining path curves using CAM engineering software.

[0036] Continue to refer to Figure 1 The tool path calculation method also includes step S2. Step S2 obtains the dynamic drive of the forming tool, which is used to drive the forming tool to make a tool motion trajectory that is close to the machining path curve, so that the tool motion trajectory is close to the ideal machining trajectory. Under the drive of this dynamic drive, the tool motion trajectory of the forming tool approximates the machining path curve.

[0037] The tool path calculation method first plans the machining path curve, that is, plans the ideal machining trajectory, and then uses dynamics to make the tool's motion trajectory approximate the machining path curve, thus opening up a technical route for obtaining tool trajectories using forming tools.

[0038] In this embodiment, the dynamic drive is a scalar force; obtaining the dynamic drive is equivalent to obtaining the scalar force. A vector force has both magnitude and direction, while a "scalar force," after coordinate transformation, only has its magnitude. The advantage of using scalar force to define the dynamic drive is that only the positions of the applying and receiving points need to be defined, along with the magnitude of the scalar force. The relative displacement of the applying and receiving points in Euclidean space is not required. When it is desired that the applying and receiving points attract each other, the magnitude of the scalar force is defined as negative; when it is desired that the applying and receiving points repel each other, the magnitude of the scalar force is defined as positive. Using scalar force as the dynamic drive, the tool motion trajectory of the forming tool approximates the machining path curve can be simulated inversely.

[0039] Continue to refer to Figure 1Obtaining the scalar force includes steps S2.1, S2.2, and S2.3. Step S2.1 defines the cutting point of the forming tool, constraining the degree of freedom of the cutting point to the machining path curve, so that the forming tool cuts along the machining path curve. Step S2.2 defines the cut point of the integral impeller, which is located on the machining path curve, so that the integral impeller is cut along the machining path curve. Step S2.3 defines the scalar force, defining the cutting point as the point of application of the scalar force, and the cut point as the point of application of the scalar force. The magnitude of the scalar force is defined as negative, and the duration of action of the scalar force is defined. The selection of the point of application of the scalar force on the machining path curve, i.e., the cut point, and the setting of the duration of action ensure that, driven by the scalar force, the tool trajectory at the point of application approaches the point of application of the scalar force, thereby making the tool trajectory approximate the machining path curve.

[0040] Scalar force is defined in a simulation environment, such as the simulation environment in UG (Unigraphics NX) software. To ensure that the tool trajectory at the force application point can approximate the machining path curve under the drive of scalar force, the scalar force is iteratively defined. The selection of the force application point on the machining path curve controls the movement of the force application point, i.e., the cutting point, to approximate the machining path curve. The application time is adjusted and set according to the distance between the force application point and the force application point, as well as the motion simulation results.

[0041] To avoid overcutting and interference between the forming tool and the integral bladed disk during actual machining, interference between the forming tool and the integral bladed disk should also be avoided during motion simulation. For example, in UG software, the forming tool and the integral bladed disk are defined as 3D contact.

[0042] The aforementioned "scalar force" is a collection of multiple scalar forces. There are multiple force points on the machining path curve, and each force point defines a scalar force. Multiple force points define multiple scalar forces, and the collection of these multiple scalar forces serves as the dynamic driver, driving the forming tool. The number of force points can be simplified to save motion simulation time. For example, only the start and end points of the machining path curve can be selected as force points, resulting in only two force points, which does not reduce the accuracy of the motion simulation.

[0043] Continue to refer to Figure 1 The tool path calculation method also includes step S3. Step S3: Obtain the tool path. Under the drive of the scalar force, the tool movement trajectory at the point of force application is the tool path. The aforementioned "tool path" is the relative motion trajectory of the forming tool relative to the overall impeller, that is, the motion trajectory of the forming tool machining the stationary overall impeller.

[0044] Figure 2 The process flow of the integral bladed disk manufacturing method is shown. For example... Figure 2As shown, the integral bladed disk machining method includes step M4, which involves machining the integral bladed disk using a forming tool. In this embodiment, the forming tool has a clearance space, and the tool holder is appropriately thickened to form the clearance space, avoiding interference during machining. This effectively improves the feasibility of one-time machining, increases the production efficiency of complex parts, saves tool wear, and reduces the time required for machining process development.

[0045] Continue to refer to Figure 2 The integral bladed disk machining method also includes step M1, which obtains the tool path of the forming tool. The tool path of the forming tool is obtained by the tool path calculation method described above.

[0046] Continue to refer to Figure 2 The integral bladed disk machining method also includes step M2, which involves obtaining the machine tool motion trajectory based on the tool path and the machine tool kinematic chain. As mentioned earlier, the tool path is the relative motion trajectory of the forming tool relative to the integral bladed disk, that is, the motion trajectory of the forming tool machining the stationary integral bladed disk. However, in actual machining, the integral bladed disk is not stationary but moves with the tooling fixture. The motion trajectory of the integral bladed disk and the motion trajectory of the forming tool work together to form the relative motion trajectory of the tool path. In order for the motion trajectories of the integral bladed disk and the forming tool to work together to obtain the target tool path, the components in the machine tool need to move along a certain motion trajectory, which is the machine tool motion trajectory. In this embodiment, the machine tool motion trajectory is obtained through motion simulation, for example, by using motion simulation in UG software based on the tool path and the machine tool kinematic chain to obtain the machine tool motion trajectory.

[0047] Continue to refer to Figure 2 The integral bladed disk machining method also includes step M3, which involves obtaining machine tool motion control commands based on the machine tool motion trajectory. These commands are generated by software based on the machine tool motion trajectory; for example, UG software generates G-code in NC code based on the machine tool motion trajectory.

[0048] Figure 3 The process of machining an integral bladed disk is illustrated in more detail using UG software as an example. Figure 3As shown, the integral bladed disk machining method includes step P1, model establishment. Step P1 includes steps P1.1, P1.2, P1.3, and P1.4. Step P1.1: Establish the integral bladed disk model and plan the machining path curve. The "integral bladed disk model" is the model of the target bladed disk obtained after machining. Step P1.2: Establish the machine tool kinematic chain model. Limit blocks need to be added at appropriate locations according to the actual situation to ensure that each movement direction in the machine tool kinematic chain does not exceed its travel limit. Step P1.3: Establish the forming tool model. The forming tool has clearance space, and the tool holder is appropriately thickened to form clearance space, avoiding interference during machining. Step P1.4: Assemble the integral bladed disk model, the machine tool kinematic chain model, and the forming tool model to form an assembly.

[0049] Continue to refer to Figure 3 The integral bladed disk machining method also includes step P2, defining the mechanical structure. Step P2 includes steps P2.1 and P2.2. Step P2.1 defines the linkage mechanism, defining each component in the assembly as a linkage mechanism, which serves as the operating element for UG motion simulation. Step P2.2 defines kinematic pairs, defining links with linear movement as sliders, links with rotational motion as revolute pairs, and links with fixed positions as fixed pairs, which serve as the basis for UG motion simulation calculations.

[0050] Continue to refer to Figure 3 The integral bladed disk machining method also includes step P3, path constraint. The degree of freedom of the cutting point of the forming tool is constrained on the machining path curve.

[0051] Continue to refer to Figure 3 The integral bladed disk machining method also includes step P4, limit setting. Step P4 includes steps P4.1, P4.2, and P4.3. Step P4.1 defines the forming tool and the integral bladed disk as 3D contact to avoid interference and overcutting. Step P4.2 defines the linear axis in the machine tool kinematic chain model and the machine tool body as 3D contact to avoid overtravel. Step P4.3 defines the rotary axis in the machine tool kinematic chain model and the machine tool body as 3D contact to avoid overtravel. During UG motion simulation calculation, a pair of entities defined as being in 3D contact are considered rigid body structures, preventing interference and also serving a limit function.

[0052] Continue to refer to Figure 3The integral bladed disk machining method also includes step P5, defining the drive. Step P5 includes steps P5.1 and P5.2. In step P5.1, a point is selected on the machining path curve as the cutting point of the integral bladed disk. A scalar force is defined, with the cutting point defined as the application point of the scalar force and the cutting point defined as the receiving point of the scalar force. The magnitude of the scalar force is defined as negative, and the duration of the scalar force is defined. The duration is adjusted based on the distance between the receiving point and the application point, as well as the motion simulation results. The selection of the receiving point (i.e., the cutting point) on the machining path curve and the setting of the duration ensure that, under the drive of the scalar force, the tool trajectory at the application point approximates the machining path curve. In step P5.2, it is determined whether all the receiving points on the integral bladed disk have been traversed. If the result is no, step P5.1 is re-executed; if the result is yes, step P6 is continued. The purpose of this step is to verify whether a scalar force is defined at all the receiving points on the integral bladed disk, ensuring that a scalar force is defined at each receiving point.

[0053] Continue to refer to Figure 3 The integral bladed disk machining method also includes step P6, defining the tracking object. Tracking points are added at the assembly anchor points of the linear and rotary axes of the machine tool kinematic chain model so as to obtain the machine tool motion trajectory with the help of UG motion simulation.

[0054] Continue to refer to Figure 3 The integral bladed disk machining method also includes step P7, UG motion simulation and machine tool motion trajectory post-processing. Step P7 includes steps P7.1 and P7.2. Step P7.1, UG motion simulation, solves the UG motion simulation environment according to the above-set conditions. Step P7.2, through UG motion simulation, obtains the movement trajectory of each tracking point, that is, the machine tool motion trajectory, and converts the coordinate values ​​in the machine tool motion trajectory into G-code in NC code to obtain machine tool motion control instructions.

[0055] Continue to refer to Figure 3 The integral bladed disk machining method also includes step P8, which involves machining the integral bladed disk using a forming tool.

[0056] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention.

Claims

1. A tool trajectory calculation method for machining a workpiece, characterized in that, The tool trajectory calculation method includes: Obtain the machining path curve of the workpiece; The dynamic drive of the tool is obtained, and under the drive of the dynamic drive, the tool movement trajectory of the tool approximates the machining path curve. The dynamic drive is a scalar force. The scalar force is obtained, and under the drive of the scalar force, the tool movement trajectory of the tool approximates the machining path curve. The tool path is obtained, and under the drive of the dynamic drive, the tool motion trajectory is the tool path.

2. The tool trajectory calculation method according to claim 1, characterized in that, The processing path curve is obtained through topology calculation.

3. The tool trajectory calculation method according to claim 2, characterized in that, The topology operations include manual topology.

4. The tool trajectory calculation method according to claim 1, characterized in that, The acquisition of scalar force includes: Define the cutting point of the tool and constrain the degree of freedom of the cutting point on the machining path curve; Define the cutting point of the workpiece, wherein the cutting point is on the machining path curve; Define the scalar force, define the cutting point as the point of application of the scalar force, define the point being cut as the point of application of the scalar force, define the magnitude of the scalar force as negative, define the duration of action of the scalar force, and define the point of application and the duration of action such that, driven by the scalar force, the tool movement trajectory at the point of application approximates the machining path curve.

5. A method for manufacturing an integral bladed disk, characterized in that, The integral bladed disk processing method includes: The integral bladed disk is machined using forming tools; The tool path of the forming tool is obtained by the tool path calculation method as described in any one of claims 1 to 4.

6. The integral bladed disk processing method according to claim 5, characterized in that, The integral bladed disk processing method further includes: Based on the tool path and the machine tool motion chain, the machine tool motion trajectory is obtained.

7. The integral bladed disk processing method according to claim 6, characterized in that, The machine tool motion trajectory is obtained through motion simulation.

8. The integral bladed disk processing method according to claim 6, characterized in that, The integral bladed disk processing method further includes: Based on the machine tool's motion trajectory, machine tool motion control commands are obtained.

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