Efficient diffuser blade milling method without tool connecting marks

Abstract

The invention discloses an efficient diffuser blade milling method without tool marks. The machining quality is improved, and the tool marks on the surface of a blade are reduced. According to the efficient diffuser blade milling method free of the tool connecting marks, the outline of a blade is formed by connecting an inner arc and an outer arc which are smoothly connected, smooth milling is adopted for blade milling, and the tool feeding position and the tool retracting position of the blade are selected on the inner arc of the blade and are adjacent to the arc of the air inlet end of a diffuser. A tangent line tangent to the outline of the blade is arranged to serve as an in-out path of the cutter, the cutter feeding position and the cutter retracting position of the blade are both located on the tangent line, smooth transition can be achieved when the cutter cuts in and out of the blade, and direct collision between the cutter and the surface of the blade is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of superchargers, and in particular to a high-efficiency and non-joint-mark milling method for diffuser blades. Background Art

[0002] As the core component of the supercharger, the performance of the diffuser directly affects the operating efficiency and life of the entire supercharger. With the continuous upgrading of the quality of supercharger products, the surface quality requirements of the diffuser have also risen accordingly. This is not only a challenge to the product precision, but also a severe test of the processing technology. Among the many processing links of the diffuser, milling blades is undoubtedly one of the difficulties. The diffuser has a complex shape, high dimensional accuracy requirements, and also needs to have sufficient strength and wear resistance. Therefore, the processing of milling blades requires not only high precision and high efficiency, but also stability and reliability during the processing.

[0003] In the process of milling diffuser blades, the current method is: first, rough milling is performed to remove most of the material and initially form the blade shape. Then, the blade is fine milled to ensure the accuracy and surface quality of the blade. In the process of fine milling diffuser blades, we currently use a traditional tool path, that is, the method of circular entry and exit from the inner arc position of the blade, and down milling. The blade fine milling method is as follows Figure 6 .

[0004] The main reason for choosing to feed from the inner arc of the blade is that, on the one hand, it can reduce the impact and vibration of the tool during the processing and reduce the wear rate of the tool; on the other hand, it can better adapt to the curved shape of the blade, reduce the resistance during the cutting process, and improve the cutting efficiency. However, after milling, this traditional feed and retract method often leaves obvious tool marks at the feed and retract positions of the blade. These tool marks not only affect the overall appearance of the blade, but also have an adverse effect on the performance and life of the blade. Therefore, it is necessary to find a more effective tool feeding method to improve this problem.

[0005] The idea behind traditional CNC programming of diffuser blade milling is to use tool offset to perform layered milling in the depth direction. Therefore, you only need to draw a diagram to confirm the tool path for fine milling. For rough milling and semi-fine milling, you only need to increase the tool radius on the basis of the tool path for fine milling.

[0006] Steps to confirm the fine milling path trajectory (the diffuser blades are evenly distributed, so only one set of blade and flow path fine milling trajectory needs to be found):

[0007] Step 1: First, draw the milling range of the tool around the blade according to the size of the blank (the flow channel milling range can be confirmed only after confirming two blades), such as Figure 3b, the distance between the blades marked in the figure = the diameter of the tool - the tool fillet. If the tool diameter is directly equal here, then in actual milling, the part of the flow channel bottom that leaves a tool fillet is not milled. It can also be seen from the figure that the triangular flow channel areas on both sides are milled and supplemented, so it is necessary to draw a picture to confirm the milling trajectory of the middle flow channel.

[0008] Step 2: Confirm the milling trajectory of the middle flow channel, such as Figure 4 The secondary trajectory needs to satisfy the requirement that the blank can be milled after the tool diameter is subtracted by 2 times the tool radius. It should be noted that the secondary trajectory needs to ensure that the blade cannot be milled when the tool has no radius, so as to prevent the blade radius from being milled. For example: the tool diameter is 20mm, the tool radius is 1.5mm, and the tool center trajectory is 8.5mm equidistant to complete the milling of the blank, and 10mm equidistant, the blade cannot be milled.

[0009] Step 3: Confirm the tool entry and exit trajectory, such as Figure 5 . Select an arc feed and retract position at a suitable position near the inner arc of the blade at the end point of the runner milling.

[0010] Step 4: Connect the found trajectory points into continuous points to form a fine milling tool trajectory, such as Figure 6 Select a safe cutting point at the outlet end to connect with the runner milling point, entry point, blade profile point and exit point. Summary of the invention

[0011] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a high-efficiency diffuser blade milling method without joint marks, thereby improving the processing quality and reducing the joint marks on the blade surface.

[0012] The object of the present invention is achieved in that:

[0013] The invention discloses an efficient diffuser blade milling method without cutting marks. The blade profile is formed by smoothly connected inner arc and outer arc. Down-cut milling is adopted for blade milling. The blade feed and retract positions are selected on the inner arc of the blade and adjacent to the circular arc of the diffuser inlet end. A tangent line tangent to the blade profile is set as the tool feed and retract path. The blade feed and retract positions are both located on the tangent line, so that the tool can smoothly transition when cutting in and out of the blade, and avoid direct collision between the tool and the blade surface.

[0014] Preferably, the diffuser blades have an airfoil-shaped profile.

[0015] Preferably, the method for confirming the entry and retract positions of the blade is: the entry point is selected at the air inlet end of the diffuser, a straight line segment is drawn through the entry point and is tangent to the arc of the inner arc of the blade, the straight line segment is used as the entry and exit path of the tool, and another straight line is drawn through the right end point of the straight line segment to connect with the end point of the flow channel milling. The two straight line segments form an obtuse angle or a right angle, and the blade is milled close to the end point of the flow channel milling by adopting a left tool deflection method. After the tool starts from the air inlet end of the blade and mills around the blade once, it retracts in the opposite direction from the entry and exit path of the tool, ends the tool deflection, and ends the blade milling.

[0016] On the one hand, the setting of obtuse angle or right angle can ensure that the tool moves along the predetermined path during the cutting process, thereby avoiding overcutting or undercutting and ensuring the processing accuracy. On the other hand, it can reduce the impact and wear of the tool when cutting in and out to a certain extent, and avoid collision or interference between the tool and the workpiece during the cutting process.

[0017] Preferably, the down milling method comprises:

[0018] Step 1: Rough milling

[0019] First, remove most of the diffuser blade excess to preliminarily form the shape of the blade. In this process, in order to ensure the accuracy of milling, the tool radius on the machine tool is set to be 0.1 to 0.2 mm larger than the actual tool radius. Then, the depth direction layered milling method is adopted, and a 0.1 to 0.2 mm excess is left after each milling.

[0020] Reasons to improve milling accuracy:

[0021] 1. Compensation for machining errors: During the rough machining stage, certain machining errors may occur due to factors such as tool wear, machine vibration, and uneven workpiece material. By reserving a margin of 0.1 to 0.2 mm, these errors can be compensated during the fine machining stage to ensure that the final machining dimensions meet the design requirements.

[0022] 2. Ensure surface quality: The main purpose of rough machining is to remove most of the excess and make the workpiece close to the final shape. However, the surface after rough machining is often rough, with defects such as tool marks and burrs. By reserving excess and performing fine machining, the surface quality of the workpiece can be further improved to obtain a smoother and flatter machined surface.

[0023] 3. Improve dimensional accuracy: In the finishing stage, due to the small allowance, the cutting force of the tool is reduced accordingly, and the vibration and deformation of the machine tool will also be controlled. This helps to control the processing size more accurately and improve dimensional accuracy.

[0024] 4. Extend tool life: Reduce the cutting load and wear of the tool during the finishing stage, thereby extending the tool life.

[0025] Step 2: Finishing

[0026] The tool radius on the machine tool is set to the same as the actual tool and processed in the depth direction. Then, the blade is fine-milled according to the pre-set CNC programming trajectory.

[0027] Preferably, the specific rough milling steps are: start feeding from the outlet end of the blade, mill along the flow channel to the inlet end of the blade, and then, along the inlet and outlet path of the tool, use G41 tool offset to perform clockwise milling to complete a full circle of processing around the blade. After completing this circle of milling, retract the tool in the opposite direction of the feed direction, and cancel the tool offset setting at the same time to complete the rough milling of a group of blades. After that, continue to perform the same milling operation on other blades by rotating the machine tool angle.

[0028] The purpose of setting tool offset: Compensating tool size: Since there will be certain dimensional errors and wear in the tool during manufacturing and use, these errors can be compensated by setting tool offset to ensure that the tool can cut according to the predetermined path and size.

[0029] The role of canceling tool offset: In the CNC programming trajectory of the entire diffuser blade milling, tool offset instructions are used for milling blades, but no tool offset instructions are used for milling flow channels. Therefore, the tool offset needs to be canceled after milling the blades to ensure that the tool trajectory for subsequent milling of flow channels matches.

[0030] To put it simply, the tool offset command is not used when milling the flow channel, but is used when milling the blades. Therefore, the tool offset needs to be canceled when retracting the tool after milling the blades. The purpose of using tool offset for milling blades is to avoid the error between the tool diameter used on site and the programmed standard tool diameter caused by tool wear. This error can be compensated by setting the tool diameter or radius on the machine tool.

[0031] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0032] Through this diffuser blade milling method, not only the processing quality of the diffuser blade is improved, but also the smoothness of the blade surface and the overall performance are ensured, the milling efficiency is improved, and the production cost is saved. This improvement helps to improve the performance of the diffuser and also extends the service life of the blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the structure diagram of the diffuser;

[0034] Figure 2 is a three-dimensional diagram of the diffuser;

[0035] Figure 3a Diffuser milling blank;

[0036] Figure 3bSchematic diagram of the milling range of the tool around the blade in the traditional milling method;

[0037] Figure 4 Schematic diagram of the tool's milling trajectory around the blade + flow channel in the traditional milling method;

[0038] Figure 5 Traditional milling method: cutting in and out;

[0039] Figure 6 Traditional finishing tool path;

[0040] Figure 7 Improved finishing milling tool trajectory;

[0041] Figure 8 Improved the rear feed and retract positions;

[0042] Fig. 9 CNC programming trajectory for rough milling blades;

[0043] Fig.10 Rough milling blade allowance diagram;

[0044] Fig.11 Schematic diagram of the position of the feed point and the end point of runner milling. DETAILED DESCRIPTION

[0045] In order to improve the machining quality and reduce the joint marks on the blade surface, we optimized the finishing milling tool path. Our optimization strategy mainly focuses on improving the feed and retract positions. The traditional feed and retract method may cause friction and collision between the tool and the blade surface, leaving obvious joint marks on the blade. To solve this problem, we use the tangential feed and retract method.

[0046] Specifically, at the blade entry and exit positions, we designed a tangent line tangent to the blade contour as the tool entry and exit path. This design allows the tool to smoothly transition when cutting in and out of the blade, effectively avoiding direct collision between the tool and the blade surface, thereby reducing the generation of tool marks.

[0047] When determining the entry and exit positions for fine milling, we need to fully consider the structural characteristics and processing requirements of the blades. The diffuser blades are in the shape of an airfoil, and their inner and outer arcs are connected by smooth arcs, which brings certain challenges to processing.

[0048] In order to meet the processing requirements of advancing and retracting from the inner arc and adopting down milling, we have carefully analyzed and decided to select the best position for advancing and retracting the tool at the position of the inner arc of the blade close to the arc on the left side of the blade. This choice is based on the following considerations:

[0049] First, entering and retracting the tool from the inner arc can ensure that the tool maintains a smooth transition with the blade surface when cutting in and out. On the one hand, it reduces the impact and vibration of the tool during the processing and reduces the wear rate of the tool; on the other hand, it further reduces the resistance during the cutting process and improves the cutting efficiency.

[0050] Secondly, choosing the position close to the arc on the left side of the blade as the entry and retraction point can make full use of the shape characteristics of the blade and make the tool more stable during the processing.

[0051] Finally, the tangential feed and retract method can ensure that the tool is tangent to the blade contour when cutting in and out, thereby avoiding obvious tool marks.

[0052] In summary, the best position for the entry and exit is selected at the position of the inner arc of the blade close to the arc on the left side of the blade, and the tangential entry and exit method is adopted, which is an efficient and high-quality fine milling solution that meets the processing requirements of the diffuser blade. Figure 7 .contrast Figure 6 It can be clearly seen that the improved trajectory is significantly shorter than before, which will correspondingly reduce the milling time and improve efficiency.

[0053] The method for confirming the entry and exit points is: the entry point is selected at the air inlet end of the diffuser, that is, the fillet at the lower left corner of the blade, and a straight line is drawn on the inner arc edge (also the inner arc) to be tangent to the arc, and then a straight line is drawn to connect with the end point of the flow channel milling. These two straight lines can be obtuse angles or right angles, but not acute angles. From the end point of the flow channel milling, the left tool is used to mill close to the blade. After the tool mills around the blade from the air inlet end of the blade, it also withdraws the tool in the straight line segment tangent to the fillet at the lower left corner of the blade (opposite to the entry direction), and the tool deflection is ended at the straight line segment perpendicular to the straight line segment, and the blade milling is ended.

[0054] The specific steps are:

[0055] Step one: rough milling.

[0056] First, we use the machine tool to remove most of the material to initially form the basic shape of the blade. In this process, in order to ensure the accuracy of milling, we deliberately set the tool radius on the machine tool to be 0.1 to 0.2 mm larger than the actual tool radius. Then, we use the method of layered milling in the depth direction and leave a margin of 0.1 to 0.2 mm after each milling.

[0057] The specific milling steps are: start feeding from a safe position at the air outlet of the blade, and mill along the flow channel to the air inlet of the blade. Then, in the tangential direction of the inner arc edge of the fillet at the air inlet end of the blade, we use G41 tool offset (i.e., down milling) to perform clockwise milling, completing a full circle of processing around the blade. After completing this circle of milling, we retract the tool in the tangential direction opposite to the feed position, and cancel the tool offset setting at the same time. In this way, the rough milling of a group of blades is completed. After that, by rotating the machine tool angle, continue to perform the same milling operation on other blades, such as Fig. 9 This is the CNC programming trajectory for milling the diffuser. Fig.10 The blade margin after rough milling is shown, which provides a basis for subsequent finishing.

[0058] Step 2: Fine milling.

[0059] In the fine milling stage of the blade, our goal is to ensure the blade's accuracy and surface quality are optimal. Therefore, on the machine tool, we set the tool radius to a value that is exactly the same as the actual tool and ensure that the depth direction is processed in place. Then, we follow the pre-set CNC programming trajectory (same as rough milling) Fig. 9 The blade is milled according to the trajectory of the blade. This step is crucial because it will directly affect the final accuracy and surface quality of the blade. Through fine milling, we can ensure that the dimensional accuracy, shape accuracy and surface roughness of the blade meet the design requirements, providing reliable guarantee for subsequent use.

[0060] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. An efficient and joint-free diffuser blade milling method, wherein the blade profile is formed by smoothly connected inner and outer arcs, characterized in that: The blade milling adopts down milling. The blade entry and exit positions are selected on the inner arc of the blade and adjacent to the arc of the diffuser inlet end. A tangent line tangent to the blade contour is set as the tool entry and exit path. The blade entry and exit positions are both located on the tangent line, so that the tool can smoothly transition when cutting in and out of the blade, avoiding direct collision between the tool and the blade surface.

2. The method for milling a diffuser blade with high efficiency and without cutting marks according to claim 1, characterized in that: The diffuser blades have an airfoil-shaped appearance.

3. The method for milling a diffuser blade with high efficiency and without cutting marks according to claim 1, characterized in that: The method for confirming the entry and retract positions of the blade is as follows: the entry point is selected at the air inlet end of the diffuser, a straight line segment is drawn through the entry point and tangent to the arc of the inner arc of the blade, the straight line segment is used as the entry and exit path of the tool, and another straight line is drawn through the right end point of the straight line segment to connect with the end point of the flow channel milling. The two straight line segments form an obtuse angle or a right angle, and the left tool deflection is used to approach the blade for milling from the end point of the flow channel milling. After the tool starts from the air inlet end of the blade and mills around the blade once, the tool is retracted in the opposite direction from the entry and exit path of the tool, and the tool deflection is ended to end the blade milling.

4. The method for milling a diffuser blade with high efficiency and without cutting marks according to claim 1, characterized in that: Down milling methods include: Step 1: Rough milling First, remove most of the diffuser blade excess to preliminarily form the shape of the blade. In this process, in order to ensure the accuracy of milling, the tool radius on the machine tool is set to be 0.1~0.2mm larger than the actual tool radius. Then, the depth direction layered milling method is adopted, and a 0.1~0.2mm excess is left after each milling. Step 2: Finishing The tool radius on the machine tool is set to the same as the actual tool and processed in the depth direction. Then, the blade is fine-milled according to the pre-set CNC programming trajectory.

5. The method for milling a diffuser blade with high efficiency and without cutting marks according to claim 4, characterized in that: The specific rough milling steps are: start feeding from the outlet end of the blade, mill along the flow channel to the inlet end of the blade, and then, along the in and out path of the tool, use G41 tool offset to perform clockwise milling to complete a full circle of processing around the blade. After completing this circle of milling, retract the tool in the opposite direction of the feed direction and cancel the tool offset setting to complete the rough milling of a group of blades. After that, continue the same milling operation on other blades by rotating the machine tool angle.

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