Thin-wall weak-rigidity flat casing machining method

Abstract

The invention discloses a thin-wall weak-rigidity flat casing machining method which comprises the following steps that S1, a part is pressed and fixed to a clamp, then a preliminary outline of a precise hole set on a part mounting edge is machined step by step through drilling, hole burying and rough boring, and the rough boring machining amount is controlled within a set range; s2, the part is taken out of the clamp, the part is pressed and fixed again, in the pressing and fixing process, a layered uniform distribution pressing method is adopted to be matched with a torque wrench to press and fix the part layer by layer step by step, the torque wrench is controlled within the set torque, meanwhile, the maximum deformation amount of the part is checked in real time when a pressing plate presses each time, and the maximum deformation amount of the part is determined; it is ensured that the part deformation is controlled within the set run-out value; s3, a complete outline of a precise hole group on the mounting edge of the part is machined step by step through semi-fine boring, fine boring and reaming, and the reaming machining amount is controlled to be a set value; compared with the prior art, the position of the precise hole in the part mounting edge is accurate and reliable, and the machining qualification rate of the part is high.

Description

Technical Field

[0001] The invention relates to the technical field of casing processing, and in particular to a method for processing a thin-walled, weakly rigid, flat casing. Background Art

[0002] In a certain type of aircraft engine, the material composition of the intermediate casing is GH625, GH3030 and other high-temperature alloy materials that are difficult to process, and the radial span of the part is much larger than the axial length. At the same time, the overall cover is flat and bowl-shaped, with a wall thickness of only 2.5 to 3.75. The front and rear mounting edges are connected in the air through a tapered arc-shaped thin wall, and each mounting boss is unevenly welded to the curved arc thin wall on the oblique side of the casing along the circumferential direction. Therefore, the intermediate casing is a typical thin-walled, weakly rigid flat structure. In addition, since the intermediate casing belongs to a certain type of aircraft engine gas generator unit, its front and rear mounting edges are precisely assembled with the centrifugal impeller cover and turbine casing respectively, so the technical requirements and related dimensions of the precision holes on its mounting edges are very high.

[0003] However, when the intermediate casing is clamped and fixed with a fixture, the large end face of the part is usually used for full-surface support, and the pressure plate is evenly distributed at multiple points around the circumference to press. However, when the whole surface of the part is supported, due to the problem of flatness control of the supporting surface of the part itself, unevenness will always occur (even within the qualified range of flatness requirements); therefore, during the clamping process of the clamp pressure plate, the part will always be subject to compression stress deformation. In addition, the existing processing methods include drilling, rough boring, fine boring and reaming. Based on the thin-walled, weak rigidity structural characteristics of the part and the low plasticity and high hardness characteristics, in order to ensure the fine boring allowance, the machining allowance during rough boring is too large, resulting in faster wear of the rough boring tool, greater rough boring cutting force, and serious tool passivation after wear, which further increases the rough boring cutting force. In addition, the reaming allowance reserved after fine boring is large, which makes the cutting force of the part larger when reaming. After the parts are processed, their stress and deformation will be converted and accumulated into changes in the precision hole size and technical requirements of the part end face after the parts deform and rebound, and it is very easy to cause out-of-tolerance; and because precision hole processing is a semi-closed cutting, the high cutting heat and chips that are difficult to break are difficult to remove away from the tool tip in time, the tool wear is more severe, and the axial force of drilling is large, and boring will produce radial force. The required tool is prone to large bending deformation, which affects the processing accuracy of the parts. At the same time, abnormal tool wear and tool hitting are prone to occur during the processing, which makes the part cutting stress deformation large and the qualified rate low. Summary of the invention

[0004] The invention provides a method for processing a thin-walled, weakly rigid flat casing, so as to solve the technical problems of compression stress deformation and cutting stress deformation in the existing intermediate casing processing process, unstable processing of the precision hole position on the installation edge, and low qualified rate.

[0005] According to one aspect of the present invention, a method for processing a thin-walled, weakly rigid, flat casing is provided, comprising the following steps: S1, pressing and fixing a part on a fixture, and then using drilling, burying and rough boring to gradually process the preliminary outline of a precision hole group on the mounting edge of the part, and controlling the rough boring processing amount within a set range; S2, removing the part from the fixture, pressing and fixing the part again, and during the pressing and fixing process, using a layered uniform pressing method in conjunction with a torque wrench to gradually press and fix the part in layers, and controlling the torque wrench within a set torque, and at the same time checking in real time the maximum deformation of the part each time the pressure plate is pressed, to ensure that the deformation of the part is controlled within a set runout; S3, using semi-finishing boring, fine boring and reaming to gradually process the complete outline of the precision hole group on the mounting edge of the part, and controlling the reaming processing amount to a set value.

[0006] As a further improvement of the above technical solution:

[0007] Furthermore, the specific steps of using a layered uniformly distributed pressing method to gradually press and fix the parts in layers are as follows: the parts are pressed into four layers, the first layer is to tighten multiple pressure plate nuts manually in sequence, the second layer is to use a torque wrench with a torque of 6N.m-7N.m to tighten multiple pressure plate nuts in sequence, the third layer is to use a torque wrench with a torque of 7N.m-8N.m to tighten multiple pressure plate nuts in sequence, and the fourth layer is to use a torque wrench with a torque of 8N.m-9N.m to tighten multiple pressure plate nuts in sequence.

[0008] Furthermore, the tightening sequence of the nuts of each laminate is the same.

[0009] Furthermore, the part is clamped at three points, and each pressure plate is clamped in sequence in a clockwise or counterclockwise direction; or the part is clamped at four points, and each pressure plate is clamped in sequence in a cross shape; or the part is clamped at six points, and each pressure plate is clamped in sequence in an interval cross star shape.

[0010] Furthermore, the torque is set to 6N.m-9N.m, and the runout is set to 0.005.

[0011] Further, the setting range is 0.5mm-0.7mm; and / or the setting amount is 0.02mm.

[0012] Furthermore, during the machining process, the rough boring cutter, fine boring cutter and reamer that are severely worn are repaired and replaced.

[0013] Furthermore, the processing parameters of drilling are: speed 500r / min, feed speed 20mm / min; the processing parameters of buried hole are: speed 600r / min, feed speed 10mm / min, cutting depth 0.5mm; the processing parameters of rough boring are: speed 800r / min, feed speed 15mm / min, cutting depth 0.6mm; the processing parameters of semi-finishing boring are: speed 1000r / min, feed speed 15mm / min, cutting depth 0.23mm; the processing parameters of fine boring are: speed 1000r / min, feed speed 12mm / min, cutting depth 0.15mm; the processing parameters of reaming are: speed 500r / min, feed speed 18mm / min, cutting depth 0.02mm.

[0014] Furthermore, the meter method is used to check in real time the maximum deformation of the part each time the pressure plate is pressed. If the deformation of the part exceeds the set runout, the support and pressing point of the pressure plate is adjusted, and the pressing and deformation checks are performed again until the deformation of the part is controlled within the set runout.

[0015] Furthermore, by controlling the processing amount of semi-finishing boring, the processing amount of rough boring is controlled within a set range, and the processing amount of reaming is controlled within a set value.

[0016] The present invention has the following beneficial effects:

[0017] The thin-walled weak-rigidity flat casing processing method of the present invention presses and fixes the parts on the fixture, and then uses drilling, countersinking and rough boring to gradually process the preliminary outline of the precision hole group on the installation edge of the parts, so as to correct the position of the precision holes after drilling by countersinking and rough boring, reduce the position deviation of the precision holes, and control the rough boring processing amount within a set range, avoid large excess feed, and control the rough boring cutting force within a reasonable range; the parts are taken out of the fixture, and the parts are pressed and fixed again, and in the pressing and fixing process, a layered uniform pressing method is used in conjunction with a torque wrench to press and fix the parts in layers step by step, and the torque wrench is controlled within a set torque, and the maximum deformation of the parts is checked in real time each time the pressure plate is pressed, to ensure that the deformation of the parts is controlled within a set runout, to realize the conversion of one pressing into multiple pressings, to reduce the pressing force when the parts are pressed each time, so that the forces on the parts during the pressing process are relatively uniform, and the maximum range is achieved. The clamping stress deformation of parts is reduced to a certain extent, and the deformation is controlled within an appropriate range by precise control of the clamping force to avoid repeated adjustments due to excessive deformation, thereby improving the clamping and fixing efficiency of parts; semi-finishing boring, fine boring and reaming are used to gradually process the complete outline of the precision hole group on the installation side of the parts, and the reaming processing amount is controlled to the set value, while ensuring the quality of precision hole processing, the reaming cutting force is minimized; compared with the prior art, this scheme reduces the cutting stress deformation after drilling by burying holes, reduces the cutting stress deformation of rough boring by semi-finishing boring, and minimizes the cutting stress deformation by precise control of the rough boring processing amount and the reaming processing amount, and minimizes the compression stress deformation by secondary clamping and fixing of parts and layered clamping and fixing, ensuring that the position of the precision holes on the installation side of the parts is accurate and reliable, the parts have a high processing qualification rate, strong practicality, and are suitable for wide promotion and application.

[0018] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 It is a flowchart of the steps of a method for processing a thin-walled, weakly rigid, flat casing according to a preferred embodiment of the present invention;

[0021] Figure 2 It is a structural schematic diagram of a thin-walled weakly rigid flat casing in a method for processing a thin-walled weakly rigid flat casing according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are 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.

[0023] like Figure 1 and Figure 2 As shown, the thin-walled weak rigidity flat casing processing method of this embodiment includes the following steps: S1, pressing and fixing the part on the fixture, and then using drilling, burying and rough boring to gradually process the preliminary outline of the precision hole group on the installation side of the part, and the rough boring processing amount is controlled within a set range; S2, taking the part out of the fixture, re-pressing and fixing the part, and during the pressing and fixing process, using a layered uniform pressing method with a torque wrench to gradually press and fix the part in layers, and the torque wrench is controlled within a set torque, and at the same time, the maximum deformation of the part is checked in real time each time the pressure plate is pressed to ensure that the deformation of the part is controlled within a set runout; S3, using semi-finishing boring, fine boring and reaming to gradually process the complete outline of the precision hole group on the installation side of the part, and the reaming processing amount is controlled to a set value.

[0024] like Figure 1 and Figure 2As shown, specifically, the thin-walled weak rigidity flat casing processing method of the present invention presses and fixes the part on the fixture, and then uses drilling, countersinking and rough boring to gradually process the preliminary outline of the precision hole group on the installation edge of the part, so as to correct the position of the precision hole after drilling by countersinking and rough boring, reduce the position deviation of the precision hole, and control the rough boring processing amount within a set range, avoid large excess feed, and control the rough boring cutting force within a reasonable range; the part is taken out of the fixture, and the part is pressed and fixed again, and during the pressing and fixing process, a layered uniform pressing method is used in conjunction with a torque wrench to gradually press and fix the part in layers, and the torque wrench is controlled within the set torque, and the maximum deformation of the part is checked in real time each time the pressure plate is pressed to ensure that the deformation of the part is controlled within the set runout, so as to realize the conversion of one pressing into multiple pressings, reduce the pressing force when the part is pressed each time, and make the force on the part relatively uniform during the pressing process. , minimize the pressing stress deformation of parts, and control the deformation within an appropriate range through precise control of the pressing force to avoid repeated adjustments due to excessive deformation, thereby improving the clamping and fixing efficiency of parts; semi-finishing boring, fine boring and reaming are used to gradually process the complete outline of the precision hole group on the installation side of the part, and the reaming processing amount is controlled to the set value, while ensuring the quality of precision hole processing, the reaming cutting force is minimized; compared with the prior art, this scheme reduces the cutting stress deformation after drilling by burying holes, reduces the cutting stress deformation of rough boring by semi-finishing boring, and minimizes the cutting stress deformation by precise control of the rough boring processing amount and the reaming processing amount, and minimizes the pressing stress deformation by secondary clamping and fixing of parts and layered clamping and fixing, ensuring that the position of the precision holes on the installation side of the parts is accurate and reliable, the parts have a high processing qualification rate, strong practicality, and are suitable for wide promotion and application.

[0025] It should be understood that the precision hole group refers to all the precision holes on the mounting side of the part.

[0026] It should be understood that buried holes and boring holes are crucial in the processing route. They can correct the hole position and the cutting allowance of the hole in time to avoid uneven hole processing allowance due to hole eccentricity, thereby causing uneven cutting force, and resulting in large local force, which drives the parts to cause hole position deviation; therefore, increasing buried holes and accurately controlling the boring processing amount can greatly improve the qualified rate of parts after processing.

[0027] It should be understood that Figure 2 As shown, due to the structure of the bevel boss on the outer ring of the part and the pipe joint, it is impossible to change the multi-point clamping to the whole surface clamping; and to change the whole surface support to multi-point support, the fixture needs to be modified, but the workload and cycle of fixture modification are large, and the risk of changing the production organization of the fixture is high, so both are not advisable; in addition, under the current process conditions, it is temporarily impossible to completely eliminate the clamping stress deformation during part clamping.

[0028] It should be understood that the processing method of this embodiment is a step-by-step precision hole group processing method, which first performs drilling processing on the precision hole group on the part installation side, then performs countersinking processing on the precision hole group on the part installation side, then performs rough boring processing on the precision hole group on the part installation side, then performs semi-finishing boring processing on the precision hole group on the part installation side, then performs fine boring processing on the precision hole group on the part installation side, and finally performs reaming processing on the precision hole group on the part installation side. Compared with processing the precision holes one by one, this can greatly reduce the cumulative deformation of the parts and improve the processing quality.

[0029] It should be understood that the existing part feed route is rough boring, fine boring and reaming. In this feed route, in order to ensure the fine boring allowance, the machining allowance during rough boring is too large, resulting in faster wear of the rough boring tool, large rough boring cutting force, and serious tool blunting after wear, which further increases the rough boring cutting force. In addition, the reaming allowance reserved after fine boring is large, which makes the cutting force when reaming the part larger. Therefore, in this embodiment, the rough boring amount and reaming amount can be reduced by adding semi-fine boring to reduce the rough boring cutting force and reaming cutting force.

[0030] In this embodiment, the specific steps of using the layered uniformly distributed clamping method to gradually clamp and fix the parts in layers are as follows: the parts are clamped in four layers, the first layer is to tighten the multiple platen nuts manually in sequence, the second layer is to tighten the multiple platen nuts in sequence using a torque wrench with a torque of 6N.m-7N.m, the third layer is to tighten the multiple platen nuts in sequence using a torque wrench with a torque of 7N.m-8N.m, and the fourth layer is to tighten the multiple platen nuts in sequence using a torque wrench with a torque of 8N.m-9N.m. Specifically, by clamping in layers, it is avoided that after one platen is clamped, the part will not be warped and deformed due to uneven force at that place and other parts, and by gradually increasing the torque of the torque wrench of each layer, it is ensured that the force on the part is relatively regular and uniform, which greatly reduces the compression stress deformation of the part.

[0031] In this embodiment, the tightening sequence of the nuts of each laminate is the same. Specifically, by ensuring that the tightening sequence of the nuts of each laminate is the same, the force on the parts is relatively regular and uniform, and the compression stress deformation of the parts is further reduced.

[0032] In this embodiment, the part is pressed at three points, and each pressing plate is pressed clockwise or counterclockwise in sequence. Specifically, when the part is pressed at three points, pressing each pressing plate clockwise or counterclockwise in sequence can ensure that the single-layer part is pressed relatively evenly, so as to reduce the compression deformation stress of the part.

[0033] In another embodiment, the part is pressed at four points, and each pressing plate is pressed in turn in a cross shape. Specifically, when the part is pressed at four points, each pressing plate is pressed in turn in a cross shape, which can ensure that the single-layer part is pressed relatively evenly to reduce the compression stress deformation of the part.

[0034] In another embodiment, the part is pressed at six points, and each pressing plate is pressed in turn by adopting an interval cross star shape. Specifically, when the part is pressed at six points, each pressing plate is pressed in turn by adopting a cross shape, which can ensure that the single-layer part is pressed relatively evenly, so as to reduce the compression stress deformation of the part.

[0035] In this embodiment, the torque is set to 6N.m-9N.m, and the runout is set to 0.005. Specifically, when the design torque is within 6N.m-9N.m, the runout when the parts are pressed can be controlled within 0.005, and the parts are ensured to be pressed to prevent the parts from loosening; when the set torque is less than 6N.m, the parts will still loosen after being pressed; when the set torque is greater than 9N.m, the runout when the parts are pressed is greater than 0.005, and re-pressing and inspection are required. In this embodiment, the setting range is 0.5mm-0.7mm. Specifically, when the setting range is 0.5mm-0.7mm, the processing efficiency and rough boring cutting force are appropriate; when the setting range is less than 0.5mm, the processing efficiency is low; when the setting range is greater than 0.8mm, the rough boring cutting force is too large.

[0036] In this embodiment, the setting amount is 0.02 mm. Specifically, when the setting amount is 0.02 mm, the part qualification rate is high and the reaming cutting force is appropriate; when the setting amount is less than 0.02 mm, the part qualification rate is low; when the setting amount is greater than 0.02 mm, the reaming cutting force is large.

[0037] In this embodiment, during the machining process, the rough boring cutter, fine boring cutter and reamer that are severely worn are ground and replaced. Specifically, by grinding and replacing the rough boring cutter, fine boring cutter and reamer that are severely worn, the blades of the rough boring cutter, fine boring cutter and reamer are ensured to be sharp, thereby reducing the cutting force during the machining process, thereby reducing the cutting stress deformation of the parts.

[0038] In this embodiment, in step S2, the processing parameters of drilling are: rotation speed 500r / min, feed speed 20mm / min; the processing parameters of buried hole are: rotation speed 600r / min, feed speed 10mm / min, cutting depth 0.5mm; the processing parameters of rough boring are: rotation speed 800r / min, feed speed 15mm / min, cutting depth 0.6mm; the processing parameters of semi-finishing boring are: rotation speed 1000r / min, feed speed 15mm / min, cutting depth 0.23mm; the processing parameters of fine boring are: rotation speed 1000r / min, feed speed 12mm / min, cutting depth 0.15mm; the processing parameters of reaming are: tool rotation speed 500r / min, feed speed 18mm / min, cutting depth 0.02mm. Specifically, by precisely controlling the machining parameters, the cutting force at each step can be controlled to ensure that the compression deformation of the parts is within a controllable range, which can greatly improve the process stability and quality reliability of precision hole group machining. In addition, in addition to reaming, the speed is gradually increased, the feed is gradually reduced, and the cutting depth is gradually reduced to reduce the cutting force, reduce tool wear, and improve machining quality.

[0039] In this embodiment, the maximum deformation of the part is checked in real time by the metering method each time the pressure plate is pressed. If the deformation of the part exceeds the set runout, the support and pressing position of the pressure plate is adjusted, and the pressing and deformation are checked again until the deformation of the part is controlled within the set runout. Specifically, in the process of layered pressing and fixing, each time the pressure plate presses the part, the maximum deformation of the part needs to be checked in real time by the metering method, and the deformation is compared with the set runout, so as to press the next pressure block, or re-press and check after adjustment, so as to ensure that the deformation of the part meets the processing accuracy requirements to the greatest extent and improve the processing qualification rate of the part.

[0040] In this embodiment, the rough boring amount is controlled within a set range and the reaming amount is controlled within a set value by controlling the semi-finishing boring amount. Specifically, the rough boring cutting force and the reaming cutting force are reduced by adding the reduction amount of the rough boring amount and the reaming amount to the semi-finishing boring amount, and the rough boring amount is controlled within a set range and the reaming amount is controlled within a set value. After the semi-finishing boring is completed, the part deformation that may be generated during the semi-finishing boring process can be eliminated by fine boring, thereby improving the part processing qualification rate.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for processing a thin-walled, weakly rigid flat casing, characterized in that: The following steps are involved: S1, press and fix the parts on the fixture, and then use drilling, counterboring and rough boring to gradually process the preliminary outline of the precision hole group on the installation side of the parts, and control the rough boring processing amount within the set range; S2, remove the part from the fixture, re-press and fix the part, and during the pressing and fixing process, use the layered uniform pressing method with a torque wrench to gradually press and fix the part in layers, and control the torque wrench within the set torque. At the same time, check the maximum deformation of the part when the pressure plate is pressed each time in real time to ensure that the deformation of the part is controlled within the set runout; S3, semi-finishing boring, finishing boring and reaming are used to gradually machine the complete outline of the precision hole group on the mounting edge of the part, and the reaming processing amount is controlled to the set value.

2. The method for processing a thin-walled, weakly rigid, flat casing according to claim 1, characterized in that: The specific steps of using the layered uniform compression method to gradually compress and fix the parts in layers are as follows: The parts tightening is divided into four levels. The first level is to tighten multiple pressure plate nuts manually in sequence. The second level is to tighten multiple pressure plate nuts in sequence using a torque wrench with a torque of 6N.m-7N.m. The third level is to tighten multiple pressure plate nuts in sequence using a torque wrench with a torque of 7N.m-8N.m. The fourth level is to tighten multiple pressure plate nuts in sequence using a torque wrench with a torque of 8N.m-9N.m.

3. The method for processing a thin-walled, weakly rigid flat casing according to claim 2, characterized in that: The tightening sequence of the nuts for each laminate is the same.

4. The method for processing a thin-walled, weakly rigid, flat casing according to claim 2, characterized in that: The parts are clamped at three points, and each clamp is clamped in turn clockwise or counterclockwise; or The parts are clamped at four points, and each clamp is clamped in turn in a cross pattern; or The parts are clamped at six points, using an interval cross star-shaped pattern to clamp each pressure plate in turn.

5. The method for processing a thin-walled, weakly rigid, flat casing according to any one of claims 1 to 4, characterized in that: Set the torque to 6N.m-9N.m and the runout to 0.

005.

6. The method for processing a thin-walled, weakly rigid, flat casing according to any one of claims 1 to 4, characterized in that: The setting range is 0.5mm-0.7mm; and / or The setting amount is 0.02mm.

7. The method for processing a thin-walled, weakly rigid, flat casing according to any one of claims 1 to 4, characterized in that: During the machining process, the rough boring cutters, fine boring cutters and reamers that are severely worn are reground and replaced.

8. The method for processing a thin-walled, weakly rigid, flat casing according to any one of claims 1 to 4, characterized in that: The machining parameters of drilling are: rotation speed 500r / min, feed speed 20mm / min; The processing parameters of buried holes are: rotation speed 600r / min, feed speed 10mm / min, cutting depth 0.5mm; The machining parameters of rough boring are: speed 800r / min, feed speed 15mm / min, and cutting depth 0.6mm; The machining parameters of semi-finishing boring are: speed 1000r / min, feed speed 15mm / min, and cutting depth 0.23mm; The machining parameters of fine boring are: speed 1000r / min, feed speed 12mm / min, and cutting depth 0.15mm; The processing parameters of reaming are: rotation speed 500r / min, feed speed 18mm / min, and cutting depth 0.02mm.

9. The method for processing a thin-walled, weakly rigid, flat casing according to any one of claims 1 to 4, characterized in that: The maximum deformation of the part is checked in real time each time the pressure plate is clamped by the meter method. If the deformation of the part exceeds the set runout, the support and clamping point of the pressure plate is adjusted, and the clamping and deformation checks are performed again until the deformation of the part is controlled within the set runout.

10. The method for processing a thin-walled, weakly rigid, flat casing according to any one of claims 1 to 4, characterized in that: By controlling the amount of semi-finishing boring, the amount of rough boring can be controlled within the set range, and the amount of reaming can be controlled within the set value.

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