A method for processing a high-temperature alloy narrow deep long thin-wall end-face groove vehicle

Abstract

The application discloses a high-temperature alloy narrow deep long thin-wall end-face groove turning method, which comprises the following steps in sequence: rough turning a rectangular groove contained in an end-face groove, semi-finishing turning an outside groove wall of the end-face groove and a part of machining allowance of a groove bottom part close to one side of the outside groove wall, semi-finishing turning an inside groove wall of the end-face groove and a part of machining allowance of a remaining groove bottom close to one side of the inside groove wall, semi-finishing turning the part of machining allowance of the groove bottom part close to one side of the outside groove wall of the end-face groove, finishing turning the part of machining allowance of the outside groove wall of the end-face groove and the part of machining allowance of the groove bottom part close to one side of the outside groove wall, finishing turning all machining allowances of the inside groove wall of the end-face groove and all machining allowances of the remaining groove bottom close to one side of the inside groove wall, and finishing turning all machining allowances of the outside groove wall of the end-face groove. The application solves the problems of easy deformation, easy interference, difficult chip removal, poor surface roughness and large tool consumption of GH4169 narrow deep long thin-wall end-face groove turning, and guarantees machining precision and a qualified rate.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine processing and manufacturing technology, specifically a method for machining narrow, deep, thin-walled end faces of aero-engine parts made of high-temperature alloys, involving the design of CNC machining methods and CNC tool design. Background Technology

[0002] like Figure 1 As shown, the material of this part is GH4169. GH4169 has excellent high-temperature strength, good fatigue resistance, creep resistance, oxidation resistance, and corrosion resistance, but poor machinability. GH4169 has a low thermal conductivity, resulting in high cutting forces and high cutting temperatures during machining, severe work hardening, and tool adhesion and rapid wear. Because the part is thin-walled, it is prone to deformation under cutting forces, making it difficult to guarantee the part's dimensions and technical specifications.

[0003] The raw material for the part is a solid forged bar, delivered after rough machining. The part requires machining an end face groove D. The minimum wall thickness of the part is 2.5mm, groove D has a 2mm undercut, and the inlet width of groove D is 1mm. Groove D is a narrow, deep, thin-walled end face groove made of high-temperature alloy material, making machining extremely difficult. The three-dimensional structure of the part is shown below. Figure 1 .

[0004] Previously, the groove depth of the end face of the parts was relatively shallow (generally not exceeding 30mm) and there was no undercut structure. The bottom of the groove was a regular structure, and the CNC machining of the parts could be achieved using conventional tools and turning methods. However, the material of this part is a high-temperature alloy, the groove opening width is 12mm, the bottom of the groove is a slope, and the groove depth is 42mm. The grooving tools that can be used have very small tool widths and very thin tool shanks. When grooving, the contact area between the tool and the workpiece is large, the tool overhang is long, and the rigidity is poor. A large cutting force and vibration are generated during cutting, making chip removal difficult and resulting in poor surface roughness of the groove. Conventional tools cannot be used. There are no precedents to refer to for tool structure design, CNC machining schemes for end face grooves, cutting parameters, etc., so we can only proceed by trial and error.

[0005] To solve the challenge of machining narrow, deep, thin-walled end face grooves in high-temperature alloys, it is necessary to address several aspects, including the planning of CNC machining schemes, cutting parameters, and the design and manufacture of dedicated CNC tools. Summary of the Invention

[0006] This invention aims to provide a machining method for narrow, deep, thin-walled end face grooves in high-temperature alloys, solving the machining problem of narrow, deep, thin-walled end face grooves on difficult-to-machine materials such as GH4169, and planning an efficient and feasible CNC machining scheme for end face grooves.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for machining narrow, deep, thin-walled end face grooves of a high-temperature alloy, the high-temperature alloy grade being GH4169, the groove depth being >30mm, the outer groove wall of the end face groove containing an undercut structure at the groove opening with the groove opening width being less than the groove depth, and the outer groove wall of the end face groove being a thin-walled structure, the machining method including:

[0009] Step 1: Rough machine a rectangular groove contained within the end face groove at the location of the end face groove, and leave machining allowances for the inner wall, outer wall and bottom of the rectangular groove from the corresponding inner wall, outer wall and bottom of the end face groove.

[0010] Step 2: Semi-finish turning removes part of the machining allowance on the outer wall of the end face groove, as well as part of the machining allowance on the bottom of the groove near the outer wall. Semi-finish turning adopts a layered feeding method along the axial direction of the end face groove.

[0011] Step 3: Semi-finish turning removes part of the machining allowance on the inner wall of the end face groove, as well as part of the remaining machining allowance on the bottom of the groove near the inner wall. Semi-finish turning adopts a layered feeding method along the axial direction of the end face groove.

[0012] Step 4: Semi-finish turning removes part of the machining allowance from the bottom of the groove near the outer side of the groove wall on the end face.

[0013] Step 5: Finish turning removes part of the machining allowance on the outer wall of the end face groove, as well as all the machining allowance on the bottom part of the groove near the outer wall, to obtain the partial dimensional features of the transition fillet between the bottom surface of the end face groove and the outer wall, as well as the partial dimensional features and inclination features of the bottom surface of the end face groove. Finish turning adopts a layered feeding method along the axial direction of the end face groove.

[0014] Step 6: Finish turning removes all machining allowances on the inner wall of the end face groove, as well as all machining allowances on the remaining bottom of the groove near the inner wall, to obtain all dimensional features of the inner wall of the end face groove, and all dimensional features and inclination features of the bottom surface of the end face groove. Finish turning adopts a layered feed method along the axial direction of the end face groove.

[0015] Step 7: Finish turn to remove all machining allowances on the outer wall of the end face groove, and obtain the undercut feature at the groove opening of the outer wall of the end face groove, all dimensional features of the outer wall of the end face groove, and all dimensional features of the transition fillet between the bottom surface of the end face groove and the outer wall. The finishing process adopts a machining method of radial layering along the end face groove.

[0016] As an option:

[0017] In steps two, three, and four, a square-headed slotted insert is used for semi-finish turning.

[0018] In steps five, six, and seven, a round-headed grooved insert is used for precision machining.

[0019] Alternatively, both the square-headed and round-headed slotted inserts are TiAlN-coated inserts with a cemented carbide substrate.

[0020] Alternatively, in steps two, three, and four, the cutting speed of the semi-finish turning is 30 m / min, the feed rate is 0.03 mm / r, and the depth of cut is 1.5 mm.

[0021] Alternatively, in steps five, six, and seven, the finishing cutting speed is 30 m / min, the feed rate is 0.1 mm / r, and the depth of cut is 0.5 mm.

[0022] Alternatively, step one may include a stress relief process following rough machining of the rectangular groove between step two.

[0023] As one approach, in step one, the machining allowances reserved on the undercut structures of the inner and outer walls of the rectangular groove are equal to those reserved on the corresponding inner and outer walls of the end face groove.

[0024] As one approach, the machining allowance removed in step two by semi-finish turning at the outer side of the end face groove is equal to the machining allowance removed in step three by semi-finish turning at the inner side of the end face groove.

[0025] As one solution:

[0026] The first tool holder is used in steps two, four and five.

[0027] A second tool holder is used in steps three and six.

[0028] A third tool holder is used in step seven.

[0029] The first, second, and third tool holders include bottom reinforcing ribs, or side reinforcing ribs, or both bottom and side reinforcing ribs. The bottom and side reinforcing ribs are located on the first, second, and third tool holders near the blade and away from the inner or outer groove wall of the end face groove.

[0030] As one option, in step seven, an L-shaped blade is used.

[0031] It should be noted that the aforementioned rectangular groove refers to a groove with a rectangular axial cross-section. The entire rectangular groove is an annular groove with a rectangular axial cross-section. In this case, the wall surface inside the annular groove corresponding to its outer diameter is defined as the outer groove wall, and the wall surface corresponding to its inner diameter is defined as the inner groove wall. The definition method for the outer and inner walls of the end face groove is the same.

[0032] It should be noted that the aforementioned bottom portion near the outer tank wall refers to defining a point on the bottom of the tank. The area from this point to the junction of the outer tank wall and the bottom is defined as the bottom portion near the outer tank wall, and the area from this point to the junction of the inner tank wall and the bottom is defined as the remaining bottom portion near the inner tank wall.

[0033] Compared with existing technologies, this invention explores a machining method for narrow, deep, thin-walled end face grooves in difficult-to-machine materials such as GH4169. It provides a feasible reference for machining such thin-walled, narrow, and deep grooves, ensuring that the groove wall is not easily deformed after machining, there is no interference, chip removal is convenient, surface roughness is good, tool consumption is low, and the machining accuracy and pass rate of the end face groove are high. Attached Figure Description

[0034] Figure 1 It is a three-dimensional structural sketch of the part to be processed;

[0035] Figure 2 This is a schematic diagram of the semi-finish turning and finish turning tool path steps in this invention;

[0036] Figure 3 This is a schematic diagram of blade #1;

[0037] Figure 4 This is a schematic diagram of blade #2;

[0038] Figure 5 This is a schematic diagram of blade #3. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0040] The solution of this invention mainly includes two aspects: a CNC machining method for narrow, deep, and thin-walled end face grooves and CNC tool design.

[0041] Design of CNC turning method for machining narrow, deep, thin-walled end face grooves:

[0042] Based on past machining experience, the key points for machining narrow, deep, thin-walled end face grooves are as follows:

[0043] 1) Select appropriate cutting tools to ensure that they have sufficient rigidity and do not interfere with each other.

[0044] For machining deep and narrow end face grooves, it is essential to select appropriate cutting tools based on the workpiece material. For GH4169 material, coated tools with a carbide substrate are recommended. More importantly, within the limits allowed by the end face groove structure, the rigidity of the tool holder should be maximized by adding reinforcing ribs. A lower cutting speed and feed rate should be used during machining. During the process, ensure the tool is sharp and that coolant is adequately poured. This will effectively reduce cutting temperature, dissipate heat, and ensure smooth chip removal, maximizing the tool's performance. This will significantly improve the vibration problem caused by insufficient tool rigidity, resulting in a substantial improvement in the surface finish of the parts.

[0045] 2) After rough turning, the machining stress of the parts must be fully eliminated before finishing can be carried out in order to eliminate the influence of stress on the machining of the parts.

[0046] For thin-walled parts, a significant amount of material typically needs to be removed from both the outer and inner walls of the end face groove through machining. After this removal, the altered structural characteristics cause an imbalance in the internal stresses, leading to a redistribution and rebalancing of the stresses. This rebalancing process can result in substantial deformation of the part. Therefore, rough machining should be performed first to ensure the part's structure closely resembles the design requirements. Following this, stress-relieving heat treatment should be initiated to remove internal stresses from the material and stresses generated during machining, ensuring the quality of the final finish.

[0047] 3) For machining deep and narrow end face grooves, it is advisable to use axial layering to effectively reduce part deformation and improve the surface quality of the parts.

[0048] Because the grooves on the machined end face are deep and narrow, the grooving cutters that can be used have very small cutter widths and thin shanks. During grooving, the contact area between the cutter and the workpiece is relatively large, the cutter overhang is long, and the rigidity is poor. This generates significant cutting forces and vibrations during cutting, making chip removal difficult and resulting in a low surface roughness of the end face groove. Using an axial layered feed method for grooving, the cutter retracts after each depth of cut, then advances again, retracts, and so on. This facilitates heat dissipation and chip removal, reducing tool wear.

[0049] CNC turning tool design:

[0050] like Figure 1 The bold black lines in the diagram represent the end face groove surface to be machined. Due to the unique structure of end face groove D, it is impossible to machine the part using conventional general-purpose CNC tools. A special cutting tool must be designed and manufactured. To maximize tool rigidity without interference, the tool mainly includes a tool holder, insert, insert positioning groove, insert clamping mechanism, and rigidity enhancement structure. The tool design drawing is shown below. Figures 3-5 This invention designs three types of combined cutting tools, namely... Figure 3 #1 blade in Figure 4#2 blade and Figure 5 The No. 3 cutting tool in the middle.

[0051] Both cutting tools #1 and #2 are grooving tools, differing only in the position of the reinforcing ribs and the placement of the inserts at the cutting tip. The reinforcing rib of cutting tool #1 is designed on the side of the tool shank that avoids the outer groove wall, as the object being machined is the outer groove wall, requiring reinforcement while avoiding machining interference. The reinforcing rib of cutting tool #2 is designed on the side of the tool shank that avoids the inner groove wall, preventing interference when cutting the inner groove wall and increasing the rigidity of the tool shank. The 60° face on the tool shanks of both #1 and #2 facilitates chip removal during grooving. Cutting tool #3 uses L-shaped inserts and is used to machine the recessed section of the undercut structure on the outer groove wall of the end face. The reinforcing rib can only be designed on the outer side of the tool shank; since most of the end face groove material has already been removed during use, chip removal is minimal, and a 60° face is unnecessary.

[0052] like Figures 3-5 As shown, in cutting tools #1 to #3, the tool shank of each tool is represented by a front view and a top view. In each drawing, the top view is the front view, and the bottom view is the top view. The bottom reinforcing rib is the part of the tool head that protrudes from the lower end of the tool shank in the front view, and the side reinforcing rib is the widened part of the tool head that protrudes from the lower end of the tool shank in the top view. That is, compared with the tool shank, the bottom of the tool head is thicker and the sides are wider, thereby increasing rigidity.

[0053] When rough machining the rectangular groove, a 0.5mm semi-finishing / finishing allowance is left on each side of the inner and outer groove walls to the inner and outer groove walls of the end face groove. The allowance at the bottom of the end face groove is quite large, reaching a maximum of 11mm. The groove bottom has a 70° angled structure with respect to the axis. Therefore, the machining path is extremely important during the semi-finishing / finishing of the end face groove. (See...) Figure 2 The proposed semi-finishing / finishing solution for the bolded black lines is as follows:

[0054] The first step is to semi-finish machine the allowance on the outer wall of the end face groove (or the outer diameter, the larger diameter groove wall), see... Figure 2 The machining outline shown in the bold black line: using the tool holder shown in #1 tool + square-headed slotted insert, using an axial layered feed machining method, removing 0.15mm of excess material from the outer wall of the end face slot, with a slot depth of 5mm;

[0055] The second step involves semi-finish machining to remove the allowance from the inner wall of the end face groove (or, in other words, the inner diameter or small diameter groove wall). See [link to relevant documentation]. Figure 2 The machining outline shown in the bold black line: using the tool holder shown in the No. 2 cutting tool and the square-headed slotting insert, the machining method of axial layered feed is adopted to remove 0.15mm of the inner wall of the end face slot and remove the remaining material at the bottom of the slot;

[0056] The third step involves semi-finish machining to remove the excess material at the connection between the outer wall of the end face groove and the bottom of the groove. (See...) Figure 2 The machining outline shown in the bold black line: using the tool holder shown in #1 tool + square-headed slotted insert, remove the remaining material at the bottom of the slot to a depth of 4.2mm.

[0057] Step 4: Finish machine the excess material on the outer side wall of the end face groove, see... Figure 2 The machining outline shown in the bold black line: using the tool holder shown in #1 and a round-headed slotted insert, the machining method of axial layered feed is used to remove the excess material from the outer groove wall and the bottom of the groove. The 70° contour of the bottom of the groove and the transition radius R2 are basically formed.

[0058] Step 5: Finish machine the excess material on the inner wall of the end face groove, see... Figure 2 The machining outline shown in the bold black line: using the tool holder shown in #2 and a round-headed groove insert, the machining method of axial layered feed is used to remove the excess material on the inner wall and bottom of the groove on the end face.

[0059] Step 6: Finish machine the excess material corresponding to the undercut on the outer wall of the end face groove, see... Figure 2 The machining outline shown in the bold black line: using the tool holder shown in #3 and an L-shaped round-headed groove insert, the semi-closed groove outline with a width of 2mm is machined in multiple steps using a radial layering machining method.

[0060] Through continuous cutting experiments, this invention has explored a suitable cutting method. Figure 1 The cutting parameters for semi-finish turning and finish turning of the groove on the upper end face of the part shown are as follows: cutting speed for semi-finish turning of the groove is 30m / min, feed rate is 0.03mm / r, and depth of cut is 1.5mm; cutting speed for finish turning of the groove is 30m / min, feed rate is 0.1mm / r, and depth of cut is 0.5mm.

[0061] The special turning tool designed and manufactured using this invention can effectively avoid machining interference and enhance tool rigidity. By rationally planning the CNC turning scheme of the parts, the machining quality of the products is guaranteed, and the CNC machining qualification rate of the parts is 100%.

[0062] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A method for machining narrow, deep, thin-walled end face grooves of a high-temperature alloy, wherein the high-temperature alloy grade is GH4169, the groove depth is >30mm, the outer groove wall of the end face groove includes an undercut structure at the groove opening and the groove opening width is less than the groove depth, and the outer groove wall of the end face groove is a thin-walled structure, characterized in that... Machining methods include: Step 1: Rough machine a rectangular groove contained within the end face groove at the location of the end face groove, and leave machining allowances for the inner wall, outer wall and bottom of the rectangular groove from the corresponding inner wall, outer wall and bottom of the end face groove. Step 2: Semi-finish turning removes part of the machining allowance on the outer wall of the end face groove, as well as part of the machining allowance on the bottom of the groove near the outer wall. Semi-finish turning adopts a layered feeding method along the axial direction of the end face groove. Step 3: Semi-finish turning removes part of the machining allowance on the inner wall of the end face groove, as well as part of the remaining machining allowance on the bottom of the groove near the inner wall. Semi-finish turning adopts a layered feeding method along the axial direction of the end face groove. Step 4: Semi-finish turning removes part of the machining allowance from the bottom of the groove near the outer side of the groove wall on the end face. Step 5: Finish turning removes part of the machining allowance on the outer wall of the end face groove, as well as all the machining allowance on the bottom part of the groove near the outer wall, to obtain the partial dimensional features of the transition fillet between the bottom surface of the end face groove and the outer wall, as well as the partial dimensional features and inclination features of the bottom surface of the end face groove. Finish turning adopts a layered feeding method along the axial direction of the end face groove. Step 6: Finish turning removes all machining allowances on the inner wall of the end face groove, as well as all machining allowances on the remaining bottom of the groove near the inner wall, to obtain all dimensional features of the inner wall of the end face groove, and all dimensional features and inclination features of the bottom surface of the end face groove. Finish turning adopts a layered feed method along the axial direction of the end face groove. Step 7: Finish turn to remove all machining allowances on the outer wall of the end face groove, and obtain the undercut feature at the groove opening of the outer wall of the end face groove, all dimensional features of the outer wall of the end face groove, and all dimensional features of the transition fillet between the bottom surface of the end face groove and the outer wall of the groove. The finishing process adopts a machining method of radial layering along the end face groove. In steps two, three, and four, a square-headed slotted insert is used for semi-finish turning. In steps five, six and seven, a round-headed grooved insert is used for precision turning. In steps two, three, and four, the cutting speed for semi-finish turning is 30 m / min, the feed rate is 0.03 mm / r, and the depth of cut is 1.5 mm. In steps five, six, and seven, the cutting speed for finish turning is 30 m / min, the feed rate is 0.1 mm / r, and the depth of cut is 0.5 mm. The machining allowance removed from the outer side of the end face groove during semi-finish turning in step two is equal to the machining allowance removed from the inner side of the end face groove during semi-finish turning in step three. The first tool holder is used in steps two, four and five. A second tool holder is used in steps three and six. A third tool holder is used in step seven. The first, second, and third tool holders include bottom reinforcing ribs, or side reinforcing ribs, or both bottom and side reinforcing ribs. The bottom and side reinforcing ribs are located on the first, second, and third tool holders near the blade and away from the inner or outer groove wall of the end face groove.

2. The method for machining narrow, deep, thin-walled end faces of high-temperature alloys according to claim 1, characterized in that: Both the square-headed and round-headed slotted inserts are TiAlN-coated inserts with a cemented carbide substrate.

3. The method for machining narrow, deep, thin-walled end faces of high-temperature alloys according to claim 1, characterized in that: Between step one and step two, there is also a stress removal process after rough machining the rectangular groove.

4. The method for machining narrow, deep, thin-walled end faces of high-temperature alloys according to claim 1, characterized in that: In step one, the machining allowances reserved on the undercut structure of the inner and outer walls of the rectangular groove are equal to those reserved on the corresponding inner and outer walls of the end face groove.

5. The method for machining narrow, deep, thin-walled end faces of high-temperature alloys according to claim 1, characterized in that: In step seven, an L-shaped blade is used.

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