Machining method of weight-reducing groove in inner cavity of gearbox and gearbox

Abstract

The application discloses a machining method of a casing inner cavity weight-reducing groove and a casing, and the machining method comprises the following steps: using a milling cutter with a diameter greater than twice the radial allowance width of the casing inner cavity weight-reducing groove, and extending the milling cutter into the casing inner cavity along an axial direction; adopting a deep hole peck drilling mode to perform axial plunge milling along the weight-reducing groove, and performing interval plunge milling along a circumferential direction for multiple times to form a plurality of lace grooves and assembly bosses; wherein, when the axial plunge milling is performed, the circumferential direction and the width direction of the radial allowance of the weight-reducing groove are combined into one layer and are milled through by one cutter. The machining method adopts the milling cutter with the diameter greater than twice the radial allowance width, improves the cutting force of the cutter, and reduces vibration and the phenomenon of broken edges in the machining process; the machining method adopts the machining mode of one cutter from top to bottom to penetrate and mill the circumferential direction and the width direction, improves the machining efficiency, and the main stress of the milling cutter in the drilling and milling process is an axial force, so that the acting force on the radial cutting force of the machine tool is greatly reduced, and the deformation of the casing can be reduced.

Description

Technical Field

[0001] This invention relates to the field of machining technology for aero-engine components, and in particular, to a method for machining a weight-reducing groove in the inner cavity of a casing and the casing itself. Background Technology

[0002] Weight reduction is a key consideration in the design of aircraft engine components. Reducing the weight of the engine casing improves aircraft performance and efficiency, while also contributing to increased engine reliability and lifespan. Therefore, many engine casings undergo milling to reduce weight in areas where assembly is unnecessary.

[0003] For example, the low-pressure turbine casing of a certain model is a crucial core component of a certain engine. It has a complex structure, thin walls, a large diameter, high dimensional accuracy, numerous slots, requires milling of a large number of mounting bosses, and necessitates welding of many parts. Machining deformation is a significant concern, affecting its machining accuracy and quality, thus impacting the overall engine performance. The turbine casing is made of GH4169. The turbine casing has a total length of 187.2 mm, a maximum diameter of 682 mm, and a minimum wall thickness of 2.5 mm, making it a typical welded thin-walled component. The inner ring of the turbine casing cavity has a weight-reduction groove 1 (see [reference needed]). Figure 1 Its location is 103.7mm deep inside the casing, and the shortest distance between the groove and the inner wall is 6.5mm. The cutting tool is limited during machining, and there is a lot of allowance. There are 7 assembly surfaces in the middle of the weight reduction groove. Because the lace groove is deep, the machine tool spindle cannot penetrate into the casing cavity with a general integral milling cutter. It is necessary to extend the cutting tool to penetrate into the casing for machining.

[0004] The following problems exist when machining the weight-reducing groove, assembly surface and mounting hole in the inner cavity of the casing: 1) The inner ring weight-reducing groove has a large allowance and is located deep, which limits the machining space, results in poor rigidity, low machining efficiency and high tool cost; 2) There are 7 deep assembly surfaces in the middle of the weight-reducing groove, which have high precision, poor machining rigidity and difficulty in ensuring dimensional accuracy; 3) There are multiple mounting holes on the weight-reducing groove, which results in intermittent cutting, low machining efficiency and high tool wear.

[0005] Currently, there are two methods for processing the weight reduction groove in the inner cavity of the casing: ① The traditional method is used. Layered milling with a shank end mill is necessary because the cutting force is high, full-cut is not possible, the tool overhang is deep, and the tool rigidity is poor. Therefore, layered machining is required in both the X and Z directions. The milling allowance for each layer is approximately 1mm (X direction) and 5mm (Z direction). The weight-reducing groove has larger allowances in the X and Z directions, approximately 6mm and 37.5mm respectively. The X direction is machined in 6 layers (1mm each), and the Z direction in 8 layers (5mm each), requiring a total of 48 milling passes. Each pass consumes one end mill, with each tool costing approximately 1723.89 yuan. The total cost is approximately 82,746 yuan, indicating extremely high tooling costs. Furthermore, the machining time is approximately 43.3min * 48 = 2079min = 34.65h, resulting in extremely low machining efficiency and significant housing deformation. ②Use Layered milling with a T-slot cutter is used. Large-diameter T-slot cutters offer better rigidity and a larger cutting area, while also allowing for increased depth of cut to improve machining efficiency. The X-axis is machined in 3 layers (2mm each), and the Z-axis in 6 layers (7mm each), requiring a total of 18 passes and 18*6=108 inserts. Each insert costs approximately 88.5 yuan, resulting in a total tooling cost of 9558 yuan. While the tooling cost is acceptable, the machining time is approximately 65min*18=1170min=19.5h, indicating low efficiency and significant casing deformation. Therefore, it is necessary to improve the existing machining method for the weight-reducing grooves within the casing cavity. Summary of the Invention

[0006] This invention provides a method for machining a weight-reducing groove in the inner cavity of a casing and a casing itself, in order to solve the technical problems of high tool wear, low machining efficiency and large casing deformation in the prior art.

[0007] According to one aspect of the present invention, a method for machining a weight-reducing groove in the inner cavity of a casing is provided, comprising the following:

[0008] Use a milling cutter with a diameter more than twice the radial allowance width of the weight reduction groove in the casing cavity, and extend the milling cutter axially into the casing cavity;

[0009] The weight reduction groove is milled axially using a deep-hole pecking drill method, and then milled multiple times at intervals along the circumference to form several decorative grooves and assembly bosses.

[0010] In the axial milling process, the radial allowance of the weight reduction groove is combined into one layer in the circumferential and width directions and milled through in one cut.

[0011] Furthermore, the diameter of the milling cutter is 2-4 times the radial allowance of the weight reduction groove.

[0012] Furthermore, the deep hole drilling method involves drilling 2-3 mm downwards along the axial direction and then retracting 0.5-1 mm, repeatedly advancing the cutter until the hole is drilled through.

[0013] Furthermore, the specific method for milling the radial allowance of the weight reduction groove along the axial and circumferential directions using a deep-hole pecking drill includes:

[0014] The mounting holes on the radial allowance of the weight reduction groove in the inner cavity of the casing are first milled using a symmetrical milling method to form several sections of allowance bosses.

[0015] Then, mill the remaining boss along the axial and circumferential directions.

[0016] Furthermore, the symmetrical milling is performed by starting milling from the axial axis of symmetry of the mounting hole, followed by left and right insertion milling, until all the excess material at the mounting hole position is removed.

[0017] Furthermore, the allowance boss is milled along the axial and circumferential directions from any end to form a decorative groove.

[0018] Furthermore, the circumferential step distance of the milling cutter is calculated according to the following formula:

[0019] S = π × D × Z / N;

[0020] Where S is the circumferential step distance; D is the diameter of the milling cutter; Z is the number of teeth of the milling cutter; N is the rotational speed of the milling cutter, wherein the number of teeth of the milling cutter (4) is 6-8, and the rotational speed of the milling cutter (4) is 500-600 r / min.

[0021] Furthermore, the feed rate of the milling cutter is 50-70 mm / r.

[0022] Furthermore, it also includes the adoption of The drill bit cleans the intersection of the lace groove and the assembly boss.

[0023] According to another aspect of the present invention, a housing is also provided, which is manufactured by the above-described method for machining the weight-reducing groove in the housing cavity.

[0024] The present invention has the following beneficial effects:

[0025] This invention employs a milling cutter with a diameter more than twice the width of the radial allowance of the weight-reducing groove in the casing cavity to provide sufficient rigidity and force support. Simultaneously, it ensures that the cutting part of the milling cutter does not exceed the center of the cutter, thereby increasing the cutting force and reducing vibration and chipping during machining. During machining, a deep-hole pecking drill is used for axial milling along the weight-reducing groove, followed by multiple circumferential milling operations. By using a milling cutter with a diameter more than twice the width of the radial allowance of the weight-reducing groove in the casing cavity, this invention enables the milling cutter to combine the circumferential and width directions of the radial allowance of the weight-reducing groove into one during axial milling. The layered, single-cut milling method improves machining efficiency by milling through the circumferential and width directions from top to bottom. Furthermore, the main force on the milling cutter during the drilling and milling process is axial force, which greatly reduces the radial cutting force exerted by the cutter on the housing. Even with a large tool overhang, it still maintains high machining rigidity, reducing housing deformation and ensuring machining stability. The top-to-bottom milling method results in a small contact area between the cutter and the housing, minimizing tool stress and avoiding issues like tool deflection and vibration. Simultaneously, the axial force on the housing during machining prevents housing deformation.

[0026] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The present invention will now be described in further detail. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 This is a schematic diagram of the internal structure of the casing.

[0029] Figure 2 This is a schematic diagram showing the location of the milled mounting holes.

[0030] Figure 3 This is a schematic diagram of a milling allowance boss.

[0031] Figure 4 This is a schematic diagram of the structure after milling.

[0032] Figure 5 This is a schematic diagram of the milling path.

[0033] Figure 6 A photograph of the milling effect of the weight reduction groove for the casing.

[0034] In the diagram: 1-weight reduction groove; 2-lace groove; 3-assembly boss; 4-milling cutter. Detailed Implementation

[0035] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0036] An embodiment of the first aspect of the present invention provides a method for processing a weight-reducing groove 1 in the inner cavity of a casing, comprising the following:

[0037] Using a milling cutter 4 with a diameter more than twice the radial allowance width of the weight reduction groove 1 in the casing cavity, the milling cutter 4 is extended axially into the casing cavity;

[0038] The weight reduction groove 1 is milled along the axial direction using a deep hole pecking drill method, and then milled multiple times along the circumferential direction at intervals to form several decorative grooves 2 and assembly bosses 3. Among them, when milling along the axial direction, the radial allowance of the weight reduction groove 1 is combined into one layer in the circumferential and width directions and milled through from top to bottom.

[0039] Specifically, see Figure 1In this embodiment, the weight-reducing groove 1 is located at a depth of 103.7 mm inside the casing cavity. The shortest distance between the groove and the inner wall is 6.5 mm. It is machined using a solid milling cutter 4. However, the machine tool spindle cannot penetrate deep into the casing cavity, so an extended tool is required to reach deeper into the casing for machining, which results in extremely poor tool rigidity. There is a large machining allowance for the weight-reducing groove 1 inside the casing cavity, requiring the milling of 7 mounting bosses 3 and 7 decorative grooves 2, which are arranged at intervals along the circumference. This invention uses a milling cutter 4 with a diameter more than twice the radial allowance width of the weight reduction groove 1 inside the casing. The cutter diameter cannot be too small to ensure that the cutting rigidity and force can meet the requirements. At the same time, the part of the cutter that participates in the cutting should preferably not be beyond the center of the cutter, because the center of the cutter is the weakest point of cutting force, with a cutting linear velocity of 0, which is in a squeezing state, resulting in increased machining vibration and causing the milling cutter 4 to chip. After the cutter is offset from the center by a certain distance, when machining the casing, the contact point at the bottom of the cutter is no longer at the center of the cutter, avoiding the center of the cutter that does not have cutting function, increasing the cutting force of the cutter, and thus improving the machining efficiency. Moreover, the area participating in the cutting should not be too small, as too small an area will affect the rigidity of the cutter and make it easy to chip. Therefore, it is best to select a cutter with a diameter more than twice the radial allowance width. This invention employs a milling cutter with a diameter more than twice the width of the radial allowance of the weight-reducing groove within the casing cavity. This allows the milling cutter to mill through the circumferential and width directions of the radial allowance of the weight-reducing groove in a single cut during axial milling. This method of milling through both the circumferential and width directions in a single cut improves machining efficiency while reducing the cutting force exerted by the milling cutter on the casing radially, minimizing casing deformation, and ensuring machining stability. In this embodiment, because the radial allowance of the weight-reducing groove 1 is greater than 6mm, to improve machining efficiency, a cutter diameter of 13–25mm is used to mill through both the circumferential and width directions in a single cut. Considering the rigidity of the cutter (due to the depth of the machining position, smaller cutters have lower rigidity) and the material being machined (high-temperature alloys, difficult-to-machine materials), a larger diameter cutter is preferred; therefore, a diameter of 24–25mm is optimal.

[0040] The radial allowance of the weight-reducing groove 1 is milled along the axial and circumferential directions using a deep-hole peck-drilling method. This deep-hole peck-drilling method involves drilling downwards along the axial direction, drilling down approximately 2mm and then retracting approximately 1mm, repeating this process until the entire groove is drilled through. Peck-milling, also known as Z-axis milling, primarily utilizes axial cutting forces, significantly reducing the radial cutting force on the machine tool. Even with a large tool overhang, it maintains high machining rigidity, minimizing casing deformation and ensuring machining stability. Peck-milling the radial allowance of the weight-reducing groove 1 along the axial direction ensures axial stress on the casing, making it less prone to deformation. During axial peck-milling, the circumferential and width directions of the radial allowance of the weight-reducing groove 1 are combined into one layer and milled through in a single pass. This single-pass milling from top to bottom through the circumferential and width allowances improves machining efficiency. The existing technology uses a machining method that involves layered milling along the radial allowance in the circumferential, width, and axial directions. It employs side-cut milling, which involves simultaneous radial and axial forces. The contact area between the tool and the housing is large, resulting in significant forces that can easily cause housing deformation. Furthermore, the machining position is deep, the tool overhang is long, and the tool rigidity is poor, which can easily lead to tool deflection and vibration problems.

[0041] This invention employs a milling cutter 4 with a diameter more than twice the radial allowance width of the weight-reducing groove 1 within the casing to provide sufficient rigidity and force support. Simultaneously, the cutting area of ​​the milling cutter 4 is kept within its center, increasing the cutting force and reducing vibration and chipping during machining. During machining, a deep-hole drilling method is used to mill the radial allowance of the weight-reducing groove 1 along both the axial and circumferential directions. Specifically, during axial milling, the circumferential and width directions of the radial allowance of the weight-reducing groove 1 are combined into one layer and milled through in a single pass. This method of milling the allowance in both the circumferential and width directions from top to bottom improves machining efficiency. Furthermore, the main force on the milling cutter 4 during the drilling and milling process is axial force, significantly reducing the radial cutting force on the machine tool. Even with a large tool overhang, it still possesses high machining rigidity, reducing casing deformation and ensuring machining stability. The milling cutter 4 mills from top to bottom, resulting in a small contact area between the milling cutter 4 and the casing, minimizing the force on the tool and avoiding tool deflection and vibration. Simultaneously, the axial force on the casing during machining does not cause casing deformation. This invention employs a single-cut milling method, with the main cutting position being the bottom edge of the tool. The tool can be re-sharpened after wear, typically requiring 2-3 re-sharpening cycles. Each housing can be machined with a new tool and one re-sharpening cycle, and two housings can be machined with three re-sharpening cycles. In contrast, with layered milling, the side edges cannot be re-sharpened after wear, and the high stress during side milling leads to rapid wear, resulting in a shorter tool life.

[0042] In this embodiment, the diameter of the milling cutter 4 is 2-4 times the radial allowance of the weight reduction groove 1; the number of teeth of the milling cutter 4 is 6-8.

[0043] The milling cutter 4 used in this invention needs to have good rigidity. Since the machining position is at a depth of 103.7 mm inside the casing cavity, the overhang length should be greater than 130 mm, and the diameter of the milling cutter 4 cannot be too small. Preferably, the diameter of the milling cutter 4 is 2-4 times the radial allowance of the weight-reducing groove 1, so that the milling cutter 4 has sufficient rigidity. In addition, the diameter of the milling cutter 4 is 2-4 times the radial allowance of the weight-reducing groove 1, which can ensure that when the milling cutter is inserted along the axial direction, the circumferential and width directions of the radial allowance of the weight-reducing groove are combined into one layer and milled through in one cut. If a small milling cutter 4 with a diameter less than twice the radial allowance of the weight-reducing groove 1 is used for machining, the tool rigidity is poor, the area to be removed is large, and the allowance is large, resulting in low machining efficiency. If a large milling cutter 4 with a diameter greater than four times the radial allowance of the weight-reducing groove 1 is used for layered machining, the tool rigidity can be increased, but the machining contact area is large, the cutting force is large, and it will cause vibration and tool deflection. In addition, the machining position is located deep inside the casing, and the dimensions are inconvenient to measure, resulting in extremely low machining efficiency. The milling cutter 4 has 6-8 teeth. Using a milling cutter 4 with more teeth results in a smaller cutting amount per tooth, and the cutting speed of the milling cutter 4 will be correspondingly faster. This is suitable for situations with high machining difficulty, complex cutting, and large machining volume. The casing of this invention is made of GH4169 alloy. Using a milling cutter 4 with 6-8 teeth can improve machining efficiency and machining quality.

[0044] In this embodiment, it is preferable to use The large allowance is removed by plunge milling with the 4-pole end mill, and then... The shank end mill 4 is used for finishing. The finishing process uses side milling to remove joint marks and ensure dimensions. Since the roughing process uses full cut and the allowance is small, the finishing process can also be completed in one cut.

[0045] In this embodiment, the deep hole pecking drill method involves drilling 2-3mm downwards along the axial direction and then retracting 0.5-1mm, repeatedly advancing the tool until the hole is drilled through. Preferably, the deep hole pecking drill method involves drilling 2mm downwards along the axial direction and then retracting 1mm. Using the deep hole pecking drill method for plunge milling can effectively reduce cutting forces, reduce tool wear, and improve tool life.

[0046] In this embodiment, the specific method for milling the radial allowance of the weight reduction groove 1 along the axial and circumferential directions using deep hole drilling includes:

[0047] The mounting holes on the radial allowance of the weight reduction groove 1 in the inner cavity of the casing are first milled using a symmetrical milling method to form several allowance bosses.

[0048] Then, mill the remaining boss along the axial and circumferential directions.

[0049] See Figure 2The machining location suffers from intermittent cutting due to the presence of a mounting base on the side of the casing. This mounting base has a through hole for housing air and oil pipes, resulting in low machining efficiency and high tool wear. The casing's inner cavity has seven evenly distributed decorative grooves 2, each with one to two oil inlet or return pipes and bleed air mounting holes, totaling 11 holes with diameters of [missing information]. and When the radius of the cutting tool is greater than the cutting tool radius, intermittent cutting occurs during machining, leading to uneven force distribution and issues such as wobbling and tool breakage. If milling is performed sequentially from left to right along the weight-reducing groove 1, the wall thickness becomes thinner after the milled portion is removed, resulting in a corresponding decrease in rigidity. When milling to the hole, because the hole diameter is more than half the cutting tool radius, the cutting position changes from being milled solid to being milled empty and then back to being milled solid, resulting in intermittent cutting and uneven force distribution on the cutting tool, causing tool wobbling and tool breakage, thus reducing tool life. Furthermore, the deformation of the casing is relatively larger in areas with relatively poor rigidity. Therefore, this invention adopts a symmetrical milling method to first mill the mounting holes on the radial allowance of the weight-reducing groove 1 inside the casing cavity. When milling the middle hole position first, the allowance on both sides is not removed during the milling process, resulting in a thicker and more uniform wall thickness and better casing rigidity. When milling the hole position, the cutting tool is limited by the allowance on both sides of the machining position, preventing tool wobbling during intermittent cutting. This eliminates tool breakage and thus improves tool life. Because the casing wall thickness is uniform and the stress is uniform during the processing, the casing deformation is relatively reduced. Deformation data: radial runout before improvement was 0.1~0.12mm, and radial runout after improvement was 0.03~0.05mm.

[0050] The method involves machining the mounting holes first, followed by machining the excess boss. On average, 0.3 milling cutters (4) are needed to machine one housing. Each cutter costs approximately 1723.89 yuan, resulting in a total tooling cost of approximately 517.167 yuan, which is low. The machining time for the seven decorative grooves (2) is approximately 1.5 hours * 7 = 10.5 hours, demonstrating high processing efficiency and stability.

[0051] See Figure 3 After machining the allowance at the mounting hole position, the allowance boss is then milled along the axial and circumferential directions. Milling can start from the right side of the allowance boss and end at another allowance boss, using the same deep hole pecking drilling method, drilling and milling from top to bottom. During the machining process, listen to the milling sound and the tool wear. If any abnormality is found, stop immediately and change the tool.

[0052] In this embodiment, the symmetrical milling begins with the axial axis of symmetry of the mounting hole as the starting point, followed by left and right insertion milling until all the excess material at the mounting hole position is removed. Specifically, a deep-hole drilling method is used, milling from top to bottom, essentially treating the milling cutter 4 as a drill bit for deep-hole drilling. The cutter drills down 2-3mm and retracts 0.5-1mm, repeatedly advancing until the hole is drilled through. After the first cut, the second and third cuts are performed with left and right insertion milling until all the excess material at the hole position is removed. When milling the middle hole position first, the excess material on both sides is not removed during the milling process, resulting in a thicker and more uniform wall thickness and better rigidity of the casing.

[0053] In this embodiment, see Figure 4 and Figure 6 The allowance boss is milled along both the axial and circumferential directions from any end to form the decorative groove 2. Since the diameter of the milling cutter 4 used in this invention is more than twice the radial dimension of the allowance, it can mill through the radial direction in one cut, and then mill the allowance boss along the circumferential direction to form the decorative groove 2. All seven decorative grooves 2 and assembly bosses 3 in this invention are milled using the same machining method. This machining method results in uniform casing wall thickness and stress distribution, and relatively reduced casing deformation.

[0054] In this embodiment, the circumferential step distance of the milling cutter 4 is calculated according to the following formula:

[0055] S = π × D × Z / N;

[0056] Where S is the circumferential step distance; D is the diameter of the milling cutter 4; Z is the number of teeth of the milling cutter 4; N is the rotational speed of the milling cutter 4, wherein the number of teeth of the milling cutter (4) is 6-8, and the rotational speed of the milling cutter (4) is 500-600 r / min.

[0057] In this invention, the weight-reducing groove 1 inside the casing is machined to a relatively deep depth. Therefore, a deep-hole drilling command is used, with seven locations evenly distributed circumferentially with machining allowances. One location is programmed, and the remaining six can be generated in an array. See [link to documentation]. Figure 5 , Figure 5 This represents the milling path. The outermost circle indicates the location to be machined, and the circles and dots are the machining points. The machined circles should not exceed the line of the outermost circle and should be as close as possible to reduce finishing allowance. After determining the machining method, the main tasks are to determine its radial depth of cut and circumferential step distance. These two parameters affect machining efficiency and tool life. Due to the tool diameter... The casing has a relatively large radial allowance of 6-7mm, which is less than half the diameter. It can be machined in one roughing pass. The circumferential step distance can be calculated according to the geometric formula. The step distance formula for milling cutter 4 is: S=π×D×Z / N. According to the machining test, when the speed N is set to 530r / min, the number of teeth Z of milling cutter 4 is set to 8, and D is set to 25mm, the step distance of 1.18mm is the optimal parameter and the best machining effect can be obtained by calculation.

[0058] In this embodiment, the milling cutter 4 rotates at a speed of 500-600 r / min, and its feed rate is 50-70 mm / r. Preferably, the milling cutter 4 rotates at a speed of 530 r / min, and its feed rate is 70 mm / r. The milling cutter 4 of this invention rotates at a speed of 500-600 r / min, and its feed rate (F) is 50-70 mm / r. The cutter speed cannot be too high; a speed exceeding 600 r / min can easily cause excessively high machining temperatures, work hardening of the cutter, and chipping of the cutting edge, affecting tool life. If the feed rate (F) is too high, the cutting depth is too large, affecting the force on the cutter, thus affecting tool life and casing deformation. Multiple machining tests have shown that a speed of 530 r / min and a feed rate of 70 mm / r result in optimal control of tool life, machining time, and machining costs.

[0059] In this embodiment, it also includes the use of The drill bit cleans the intersection of the lace groove and the mounting boss. This invention employs... After the end mill is used for plunge milling, it is still necessary to use... The side milling of the shank end mill is used for finishing, removing joint marks and ensuring the dimensions of the decorative groove and mounting boss, while also employing... The drill bit cleans the root of the intersection of the lace groove and the assembly boss to ensure that the root R1 at the intersection of the lace groove and the assembly boss is qualified and that the excess is removed.

[0060] According to another aspect of the present invention, a housing is also provided, which is manufactured by the above-described method for machining the weight-reducing groove in the housing cavity.

[0061] Table 1 shows a comparison of the process parameters between the conventional milling method and the machining method of the present invention.

[0062] Table 1 compares the traditional milling method with the machining method of the present invention.

[0063]

[0064] Note that in the table, X, Y, and Z represent the circumferential, width, and axial directions of the radial allowance, respectively.

[0065] As can be seen from the table above, by improving the processing method and tool selection, this invention is superior to... The traditional method of layered milling with a shank end mill can save 1449 minutes of milling time, 47.7 tools per piece, and 82229.553 yuan in tooling costs. This invention, compared to... The traditional method of layered milling with a milling cutter can save 540 minutes of milling time, 107.7 tools per piece, and 9040.833 yuan in tool costs.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for machining a weight-reducing groove in the inner cavity of a casing, characterized in that, Includes the following: Using a milling cutter (4) with a diameter of 2-4 times the radial allowance of the weight reduction groove (1) in the casing cavity, the milling cutter (4) is inserted into the casing cavity axially; The weight reduction groove (1) is milled along the axial direction by deep hole drilling and then milled multiple times along the circumferential direction to form several decorative grooves (2) and assembly bosses (3); among them, when milling along the axial direction, the radial allowance of the weight reduction groove (1) is combined into one layer in the circumferential and width directions and milled through from top to bottom. The specific method for milling the radial allowance of the weight reduction groove (1) along the axial and circumferential directions using deep hole pecking drilling includes: The mounting holes on the radial allowance of the weight reduction groove (1) in the inner cavity of the casing are milled using symmetrical milling to form several allowance bosses. Then, mill the remaining boss along the axial and circumferential directions; The symmetrical milling is to start milling from the axial axis of symmetry of the mounting hole, and then perform left and right insertion milling until all the excess material at the mounting hole position is removed. Mill the allowance boss along the axial and circumferential directions from any end of the allowance boss until a lace groove is formed (2).

2. The method for machining the weight-reducing groove in the inner cavity of the casing according to claim 1, characterized in that, The deep hole drilling method involves drilling 2-3mm downwards along the axial direction and then retracting 0.5-1mm, repeatedly advancing the cutter until the hole is drilled through.

3. The method for machining the weight-reducing groove in the inner cavity of the casing according to claim 1, characterized in that, The circumferential step distance of the milling cutter (4) is calculated according to the following formula: S = π × D × Z / N; Where S is the circumferential step distance; D is the diameter of the milling cutter (4); Z is the number of teeth of the milling cutter (4); N is the rotational speed of the milling cutter (4); wherein the number of teeth of the milling cutter (4) is 6-8, and the rotational speed of the milling cutter (4) is 500-600 r / min.

4. The method for machining the weight-reducing groove in the inner cavity of the casing according to claim 3, characterized in that, The feed rate of the milling cutter (4) is 50-70 mm / r.

5. The method for machining the weight-reducing groove in the inner cavity of the casing according to claim 1, characterized in that, It also includes using a φ2mm drill bit to clean the intersection of the lace groove (2) and the mounting boss (3).

6. A casing, characterized in that, It is manufactured using the machining method of the weight reduction groove in the inner cavity of the casing as described in any one of claims 1-5.

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