Water-drop-shaped chip-breaker for fine broaching of mortise of aircraft engine

Abstract

This invention relates to a teardrop-shaped chip divider for precision broaching of tenon grooves in aero-engines, belonging to the field of aero-engine manufacturing technology. The chip divider features a smooth contour composed of arcs and straight lines within a specific range, and is tangentially connected to the back face of the cutting teeth. This results in a large, smooth, streamlined cross-section without sharp points, effectively solving the industry problem of sharp-cornered chip dividers scratching the machined surface of the workpiece during precision broaching. While ensuring chip breaking and chip separation functions, it significantly improves the surface roughness quality of the tenon groove. It is suitable for precision broaching of high-requirement parts such as compressor discs and fan discs, improving blade machining efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of tool structure, and in particular relates to a teardrop-shaped chip divider for precision broaching of tenon grooves in aero-engines. Background Technology

[0002] The tenons and grooves of aero-engine turbine disks and compressor disks are used to connect blades, and their machining quality directly affects the reliability and lifespan of the engine. Currently, broaching is the primary process for machining these high-precision tenons and grooves. Turbine disk tenons and grooves are characterized by complex shapes, high dimensional accuracy requirements, and stringent surface quality requirements, and are typically machined using specialized broaching tools. During precision broaching, especially when machining difficult-to-machine materials such as high-temperature alloys and titanium alloys, chip curl control is crucial to the dimensional accuracy and surface quality of the tenons and grooves. Effective chip separation is one of the key factors affecting the stability and machining quality of the broaching process. However, see... Figure 1 As shown, when traditional chip-breaking groove types (such as 90° or 60° V-grooves or U-grooves) are applied to the cutting teeth of profile broaches, the following defects exist in the finishing stage:

[0003] The sharp points on the edge of the chip divider can scratch and abrade the already formed high-precision tenon groove surface, or leave dents and micro-steps. These damages can seriously compromise the surface integrity of the parts and may become the source of fatigue cracks, thus posing a potential threat to the safe operation of aero engines.

[0004] Therefore, existing broaches cannot simultaneously achieve "effective chip separation" and "ensure surface machining quality," resulting in low efficiency. Summary of the Invention

[0005] In view of this, the present invention uses a teardrop-shaped chip divider for precision broaching of aero-engine tenons and slots, which solves the technical problem of low efficiency in the existing broaching process for blade tenons and slots.

[0006] A teardrop-shaped chip divider is used for precision broaching of tenon grooves in aero-engine components such as turbine disks, press disks, and fan disks. The machining process includes a chip divider body mounted on the cutting teeth of a broach. The body is formed by a smooth contour composed of multiple arcs and straight lines (or no straight lines), and connects with the profile and back face of the broach cutting teeth, such as tangentially, so that the cross-section of the chip groove is a smooth streamline without sharp points. The purpose is to use a smooth and continuous arc surface or a combination of arc surface and straight lines to form a "teardrop-shaped" chip groove. The teardrop-shaped chip groove has the characteristic that all profiles are smooth and unobstructed, and its arcs can keep the chip segments away from the tenon profile, preventing scratches and damage to the tenon profile.

[0007] Preferably or optionally, the body includes at least a first arc r at the bottom of the groove and second arc R on both sides of the first arc r, wherein the center of the second arc R faces the broach body and the center of the first arc r faces the blade profile. The purpose is to protect the machined profile to the greatest extent while effectively separating and controlling the chips, thereby improving surface integrity and part fatigue performance. The profile of the cutting tooth is smoothly tangent to the second arc R, and the two ends of the second arc R and the first arc r are smoothly transitioned. In other words, "the profile of the cutting tooth smoothly transitions to the body through the second arc R, avoiding the formation of sharp points at the edge of the chip groove that could scratch or abrade the already formed high-precision tenon groove profile, or leave dents or micro-steps."

[0008] Preferably or optionally, the included angle between the tangents at the two endpoints of the first arc r is 90°-120°, and the arc length of the first arc r is less than the arc length of the second arc R. The purpose is to improve the structural strength of the cutting tool teeth.

[0009] Preferably or optionally, the ratio of the radii of the first arc r to the second arc R is 1:3 to 1:5. The purpose is to ensure the core functions of chip breaking and chip flow control of the chip divider groove while protecting the profile.

[0010] Preferably, or optionally, the groove reference width of the body is 1mm, the straight lines on both sides of the first arc r form a 100° angle, and are tangent to the second arc R on both sides through straight line segments, wherein, When there is no straight line segment between the second arc R and the first arc r, the first arc r is tangent to the second arc R on both sides.

[0011] Secondly, a broach for finishing is provided, used for machining tenons with a depth greater than or equal to 30mm. The broach has axially spaced cutting teeth, characterized in that at least one cutting tooth has some or all of the chip-breaking grooves described above. The teardrop-shaped chip-breaking groove is composed of a combination of arcs and straight lines within a specific parameter range, forming a smooth, streamlined contour without sharp points. The contour is tangentially connected to the back face of the cutting tooth, and the overall cross-section presents a smooth teardrop shape. The center of arc R faces the broach body, and the center of arc r faces the workpiece surface, achieving the dual goals of smooth chip curling and scratch-free surface protection.

[0012] Preferably or optionally, chip-breaking grooves are provided on all cutting teeth along the length of the broach, and the chip-breaking grooves are staggered along the length of the broach; or, chip-breaking grooves are provided at intervals on the cutting teeth along the length of the broach, and the chip-breaking grooves are staggered along the length of the broach.

[0013] Preferably or optionally, at least one chip-breaking groove is provided on each cutting tooth.

[0014] The beneficial effects of the present invention are as follows: The body features a smooth linear structure formed by multiple arcs, eliminating surface scratches at the source. Its completely smooth, streamlined contour has no sharp edges, thoroughly preventing scratches and damage to the machined surface during precision broaching. This avoids microscopic steps, dents, burrs, and other surface defects, significantly improving the integrity of the tenon groove surface. It effectively optimizes cutting process stability, and the teardrop-shaped streamlined groove guides chips to curl smoothly and break evenly, reducing cutting force and vibration, minimizing abnormal tool wear, and improving dimensional accuracy and surface consistency. It is suitable for long-term continuous batch processing, achieving a balance between chip separation and structural strength. For example, at 100°... The design of the groove angle and double arc ratio ensures efficient chip separation and breaking while significantly improving the structural strength of the chip-splitting groove. It can be adapted to heavy-duty machining conditions of large deep tenon grooves. Therefore, this invention can directly improve the reliability of key engine components. The defect-free smooth surface reduces the stress concentration level of parts and extends fatigue life. It directly enhances the service safety and stability of key components such as turbine disks and compressor disks of aero-engines. It solves the problem of chip separation in precision broaching of large deep tenon grooves with a depth greater than 30mm. It can achieve efficient machining without sacrificing surface quality and is perfectly adapted to the precision broaching requirements of difficult-to-machine aerospace materials such as high-temperature alloys and titanium alloys. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is the structure of a trough in the existing technology; Figure 2 This is a schematic diagram of the main body of the present invention; Figure 3 This is a schematic diagram showing the staggered arrangement of odd-numbered and even-numbered chip grooves on the broach of the present invention. Detailed Implementation

[0017] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0018] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0019] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0020] like Figures 2 to 3 As shown, this invention aims to overcome the technical shortcomings of traditional chip-breaking grooves, which easily scratch the finished surface, and the inability of chip-breaking groove-less structures to meet the chip-breaking requirements of large, deep tenon grooves. Through the design of the main body, it achieves dual assurance of chip-breaking function and the quality of the machined surface during precision broaching, significantly improving the machining accuracy, surface integrity, and fatigue life of aero-engine tenon grooves. Following the standard process for chip-breaking groove-less broaches, the broach's overall profile is ground. Based on the requirements of the tenon groove precision broaching process, the cutting cone is ground, and a standard tooth rise of 0.005–0.02 mm is strictly guaranteed to complete the machining of the broach's basic structure.

[0021] Chip-breaking groove grinding and forming: In the profile grinding process, a special grinding wheel that is perfectly matched with the teardrop-shaped chip-breaking groove is used to grind the back face of the grouped cutting teeth. The teardrop-shaped groove with a 100° included angle straight line, large circle R, and small circle r is smoothly connected in one go, ensuring the parameter accuracy of 1mm groove opening reference width and 0.2~0.4mm groove depth.

[0022] For finishing broaches, the cutting teeth profiles can be staggered: the broach cutting teeth are divided into odd-numbered tooth groups and even-numbered tooth groups, and the two groups are ground using staggered grinding wheel profiles, so that the chip-breaking grooves of adjacent cutting teeth are staggered, avoiding continuous machining marks on the machined surface. Alternatively, chip-breaking grooves can be set at intervals along the cutting teeth along the broach body axis (suitable for cases with large tooth rise, requiring three consecutive cutting teeth as a group, in which case there are at least 3 cutting teeth), and the chip-breaking grooves along the broach body axis are all staggered to meet the needs of large tooth rise machining. They can also be set alternately or at intervals according to the odd and even number of cutting teeth.

[0023] Example 1: Precision broaching of tenon grooves on GH4169 high-temperature alloy turbine disk The object being machined is a tenon groove for an aero-engine turbine disk, with a groove depth of 35mm, and the material is GH4169 nickel-based high-temperature alloy. The broach uses the teardrop-shaped chip-breaking groove of this invention, with structural parameters set as follows: large arc R=0.5mm, small arc r=0.3mm, groove depth 0.3mm, and the chip-breaking grooves are arranged in an alternating pattern. The cutting parameters are set to a broaching speed of 2m / min. Post-machining inspection results show that the chips are evenly divided, smoothly curled, and without tool entanglement or chip blockage; the microstructure of the tenon groove surface is free of defects such as grooves, scratches, and dents; the surface roughness meets the high-precision requirement of Ra≤0.4μm; the dimensional accuracy is stable and meets the standard; and the fatigue performance of the part is improved by more than 20% compared to traditional machining methods.

[0024] Example 2: Precision broaching of tenon grooves on TC6 titanium alloy compressor disc The object being machined is a tenon groove for an aero-engine compressor disk, with a groove depth of 32mm and the material being TC6 titanium alloy. The broach's teardrop-shaped chip-breaking groove parameters are: large radius R=0.5mm, small radius r=0.3mm, groove depth 0.25mm, and the chip-breaking grooves are arranged in an alternating pattern. The cutting parameters are set to a broaching speed of 5m / min.

[0025] During the machining process, the cutting force is reduced by 15%, the cutting vibration is significantly reduced, the surface is free of micro-defects, the surface integrity is excellent, and there are no scratches common in traditional chip grooves, which fully meet the high-precision machining standards for aero-engines.

[0026] Example 3: Batch processing of large deep tenons The machining target was a large tenon groove for a fan disc with a depth of 40mm, made of TC4 titanium alloy. The broach's teardrop-shaped chip flute parameters were: large radius R=1.0mm, small radius r=0.25mm, radius ratio 1:4, and groove depth 0.4mm. During continuous batch machining, the tool wear rate was reduced by 30%, the tenon groove dimensions remained consistent, no surface defects resulted in scrapped parts, and machining efficiency was increased by 25% compared to traditional chip-flute-less broaches, demonstrating excellent stability in engineering applications.

[0027] The teardrop-shaped chip divider features a smooth groove structure, with its arc segment guiding the chips to curl along the arc surface. At each differential point, the chip flow direction is along the normal direction of its respective cutting edge, thus exhibiting a component deviating from the normal direction of the tenon groove surface. The contact tendency between the chip and the tenon groove surface gradually transitions from contact to separation. Simultaneously, when the arc edge of the chip divider slides over the machined surface, its smooth edge does not produce a secondary cutting effect. This effectively avoids scratching the surface by the chip tip, reduces the risk of stress concentration, and its industrial applicability is as follows: The teardrop-shaped chip groove structure of this invention is suitable for precision broaching of tenons and grooves in key components such as turbine disks, compressor disks, and fan disks of aero-engines. It is especially suitable for machining large deep tenons and grooves with a depth greater than 30mm and machining difficult-to-machine materials such as high-temperature alloys and titanium alloys. It can be directly applied to the design and production of precision broaches and batch machining of tenons and grooves in the field of aero-engine manufacturing, which can significantly improve machining quality and efficiency and has outstanding industrial practical value.

[0028] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A teardrop-shaped chip divider for precision broaching of tenon grooves in aero-engines, suitable for machining large face tenon grooves on disc parts, characterized in that, The body includes a chip-breaking groove, which is disposed on the cutting teeth of the broach, wherein, The body is formed by a smooth contour consisting of multiple arcs or a combination of multiple arcs and straight lines, and is tangentially connected to the back face of the cutting teeth on the broach, so that the cross-section of the chip groove is a smooth streamline without sharp points.

2. The chip-distributing groove according to claim 1, characterized in that, The body includes at least a first circular arc r and a second circular arc R, wherein... The center of the second arc R faces the broach body, and the center of the first arc r faces the blade profile. The profile of the cutting tooth is smoothly tangent to the second arc R, and the two ends of the second arc R are smoothly connected to the first arc r.

3. The chip-distributing groove according to claim 2, characterized in that, The angle between the tangents at the two endpoints of the first arc r is 90°-120°, and the arc length of the first arc r is less than the arc length of the second arc R.

4. The chip-distributing groove according to claim 3, characterized in that, The ratio of the radii of the first arc r to the second arc R is 1:3 to 1:

5.

5. The chip-distributing groove according to claim 3, characterized in that, The groove reference width of the body is 1mm, the straight lines on both sides of the first arc r form a 100° angle, and are tangent to the second arc R on both sides through straight line segments. When there is no straight line segment between the second arc R and the first arc r, the first arc r is tangent to the second arc R on both sides.

6. The chip-distributing groove according to claim 1, characterized in that, The depth h of the body is 0.2 to 0.4 mm.

7. A broach for finishing, suitable for machining mortise grooves with a depth greater than or equal to 30 mm, characterized in that, At least one of the cutting teeth is provided with a chip-breaking groove as described in any one of claims 1 to 6.

8. The broach according to claim 7, characterized in that, The chip-breaking grooves are provided on all the cutting teeth along the length of the broach, and the chip-breaking grooves along the length of the broach are staggered. Alternatively, the chip-breaking grooves are provided at intervals on the cutting teeth along the axial direction of the broach body, and the chip-breaking grooves along the length of the broach are staggered.

9. The broach according to claim 8, characterized in that, At least one chip-breaking groove is formed on each cutting tooth.

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