Method for machining precise positioning hole of aero-engine central transmission frame

Abstract

The application discloses an aero-engine central transmission frame precision positioning hole position machining method, the central transmission frame has a steel sleeve hole and an axial inner hole, the precision positioning hole is used as a reference to guarantee the position degree of the steel sleeve hole, and comprises the following steps: S1, grinding two steel sleeve holes; S2, using a clamp to clamp the central transmission frame part to perform precision positioning hole boring machining, and the boring machining process comprises the following steps: S21, aligning the clamp supporting surface before machining; S22, aligning the axes of the two steel sleeve holes to perform angular positioning; S23, aligning the axial inner hole reference; and S24, boring machining the precision positioning hole and measuring. The machining method can greatly shorten the measuring time, according to statistics, one batch is machined in 2-3 days before, and quality problems are caused by being easy to adjust and misdirect; and now one batch can be machined in 4 hours, one piece in 10 minutes, and the clamp designed in the application has an error prevention effect, and can prevent unqualified products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision hole machining, in particular to a precision positioning hole machining method for an aero-engine central transmission frame. BACKGROUND

[0002] The central transmission frame, an important part of an aero-engine, needs to take the steel sleeve hole as a reference to machine a precision positioning hole to ensure the hole position degree. In the past, in the grinding process, the grinding of the reference steel sleeve hole needs to ensure a certain positioning hole position degree, and the positioning hole fine boring needs to be adjusted according to the three-coordinate measurement of the grinding process, which is prone to errors and problems such as adjustment of the processing direction offsetting the direction and reversing the direction.

[0003] The above-mentioned traditional processing strategy is as follows: first, grinding the steel sleeve hole to ensure the positioning hole position degree of the steel sleeve reference hole; second, disassembling the part, sending it to the three-coordinate measurement, recording the measurement results, and then installing the part on the precision boring machine to fine bore the hole in the subsequent fine boring process, manually analyzing the measurement results, adjusting the coordinate processing according to the coordinate deviation, and ensuring the positioning hole position degree. Since the measurement results need to be manually judged, errors are prone to occur, and the grinding process requires high skills. The part needs to be clamped twice and measured twice during the boring of the positioning hole, and the auxiliary time is long. The part needs to be 100% measured, and the processing efficiency is low, the value-added value is high, and the processing quality is poor. The grinding flowchart in the traditional processing flow is shown in the accompanying drawings, and the boring flowchart is shown in the accompanying drawings. Figure 1 Figure 2

[0004] Patent No. CN112405122A discloses a high-precision machining method for a center transmission shell bearing hole group of an engine, which includes the following steps: S1, completing the initial clamping of the engine center shell in the precision five-axis machining center; the engine center transmission shell includes a center circle, two chromium-plated bearing holes arranged on both sides of the center circle, and a non-chromium-plated bearing hole located above one of the chromium-plated bearing holes; the plane where the bottom of the chromium-plated bearing hole is located is taken as the Z-direction reference of the machining coordinate system, and the axis of the center circle is taken as the origin and Z-axis direction of the machining coordinate system; S2, determining the accurate position of the engine center transmission shell in the precision five-axis machining center through in-machine measurement; S3, establishing the machining coordinate system of the engine center transmission shell in the precision five-axis machining center; S4, grinding the chromium-plated bearing hole; and S5, boring the non-chromium-plated bearing hole. The present application has the advantages of ensuring the quality stability of the machining of the center transmission shell bearing hole group, improving the processing efficiency, and enabling mass production. Although this patent is also aimed at machining the part hole system on the aero-engine to ensure the position degree, its technical solution is to machine the bearing hole by using the precision five-axis machining center, which has high processing cost and is not suitable for machining the precision positioning hole on the above-mentioned central transmission frame.

[0005] ​​A bearing support bushing hole machining method is disclosed in patent CN115647854A. The side surface of the base away from the bushing hole is taken as the reference end surface A surface. After the remaining surfaces of the bearing support are finished and the part fixing position is converted, the first bushing hole and the reference end surface A surface are finished. The reference end surface A surface is processed first, then calibrated, the center axis of the first bushing hole is reset, and the first bushing hole is precisely bored to ensure the stability of the distance from the center axis of the first bushing hole to the reference end surface A surface, thereby ensuring the position degree of the first bushing hole of the part. The patent also has multiple calibration and measurement operations during the machining process of the bushing hole, and requires 100% measurement, which cannot solve the problem of precise positioning hole machining mentioned above. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the defects of the prior art and provide an aero-engine central transmission frame precise positioning hole hole position machining method which can significantly improve machining efficiency, reduce detection time and has good machining quality.

[0007] The object of the present application is achieved by the following technical solutions:

[0008] An aero-engine central transmission frame precise positioning hole hole position machining method, the central transmission frame has a steel sleeve hole and an axial inner hole, and the precise positioning hole is positioned with the steel sleeve hole as a reference to ensure the position degree, characterized in that it comprises the following steps:

[0009] S1. Grinding two steel sleeve holes;

[0010] S2. Adopting a clamp to clamp the central transmission frame part for precise positioning hole boring machining, and the boring machining process comprises the following steps:

[0011] S21. Aligning the clamp supporting surface before processing;

[0012] S22. Aligning the axes of the two steel sleeve holes for angular positioning;

[0013] S23. Aligning the axial inner hole reference;

[0014] S24. Boring the precise positioning hole and measuring.

[0015] Further, the two steel sleeve holes in S1 are once ground to size.

[0016] Further, in S21, the clamp supporting surface is aligned so that the supporting surface runout is not greater than 0.01.

[0017] Further, in S22, the axes of the two steel sleeve holes are aligned so that the runout is not greater than 0.01.

[0018] Further, in S23, the axial inner hole reference is aligned so that the runout is not greater than 0.01.

[0019] Further, the parts in S24 only need to be measured once.

[0020] Further, in S24, the first, middle and last parts in each batch only need to be measured.

[0021] Further, the fixture in S2 includes a mounting seat provided with an axial hole for mounting the part, a through hole is formed in the sidewall of the mounting seat, a guide seat is mounted in the through hole, the guide seat has an inner hole, a dial indicator is slidably arranged in the inner hole, one end of the dial indicator is provided with a dial indicator, and the other end is provided with a measuring head, and the dial indicator can move axially along the axis of the inner hole so that the end portion with the measuring head enters the two steel sleeve holes of the central transmission frame in sequence.

[0022] Further, the mounting seat further includes a pressing mechanism for pressing the end face of the part.

[0023] Further, in S21, the step of aligning the clamping fixture abutting surface is that the end portion of the dial indicator with the measuring head is withdrawn from the axial hole of the mounting seat, the runout of the dial indicator is determined, and the runout is not greater than 0.01.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1) In the grinding process, the two steel sleeve holes can be directly ground in place without leaving a margin, and the grinding process does not need to be measured, and compared with the traditional machining process, two position degrees can be cancelled, and the actual coordinates of the precise positioning hole do not need to be measured and recorded; in the boring process, only the machining platform, the dial indicator of the fixture and the two steel sleeve holes of the part need to be aligned, so that the axes of the three are consistent, and the precise positioning hole can be directly machined in place, and the boring process needs to be measured only once, and the first, middle and last three parts in each batch can be measured;

[0026] 2) The fixture designed in the present application determines the angular coordinates of the fixture by straightening the outer circle of the dial indicator, quickly straightens the two steel sleeve holes of the part through the dial indicator of the fixture, determines the angular coordinates of the part, and makes the angular coordinates of the fixture and the angular coordinates of the part consistent; and smoothly assists the efficient and high-quality machining of the part;

[0027] 3) The machining method can greatly shorten the measurement time, according to statistics, one batch was processed in 2-3 days before, and the quality problem was caused by easy adjustment error, while now one batch can be processed in 4 hours, one piece in 10 minutes, and the fixture designed in the present application has an error prevention function, which can prevent the occurrence of unqualified products. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The size of the central transmission frame described in embodiment 1 of the present application is shown in the size diagram;

[0029] Figure 2 The grinding machining process diagram in the machining method described in embodiment 1 of the present application is shown in the size diagram;

[0030] Figure 3 Boring machining flow chart for the machining method described in Embodiment 1 of the present application;

[0031] Figure 4 Sectional view of the fixture described in Embodiment 2 of the present application;

[0032] Figure 5 Top view of the fixture described in Embodiment 2 of the present application;

[0033] Figure 6 Dimensional schematic view of the central transmission frame corresponding to the conventional machining method in Comparative Example 1;

[0034] Figure 7 Grinding machining flow chart for the conventional machining method in Comparative Example 1;

[0035] Figure 8 Boring machining flow chart for the conventional machining method in Comparative Example 1. DETAILED DESCRIPTION

[0036] In order to clearly illustrate the technical features of the scheme, the technical scheme will be described below in detail with specific embodiments and in conjunction with the accompanying drawings.

[0037] In the following description, a lot of specific details are set forth in order to facilitate a thorough understanding of the application, however, the application can also be implemented in other ways different from those described herein, therefore, the protection scope of the application is not limited by the specific embodiments disclosed below.

[0038] In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0039] In this application, unless specifically defined otherwise, the terms "mounting", "connected", "connection", "fixed", and the like, should be construed broadly and can be either fixed connections or detachable connections, or integral; can be mechanical connection, or electrical connection, or communication; can be direct connection, or indirect connection through intermediate medium, or the internal communication of two elements, or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0040] In this application, unless specifically defined otherwise, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0041] Embodiment 1

[0042] An aero-engine central transmission frame precision positioning hole hole position processing method, the central transmission frame has a steel sleeve hole and an axial inner hole, the precision positioning hole is referenced to the steel sleeve hole to ensure the position degree, comprising the following steps:

[0043] S1. Grinding two steel sleeve holes, both steel sleeve holes are once ground to size, the specific grinding process is shown in Figure 2 , grinding one steel sleeve hole first, and then grinding the other steel sleeve hole after rotating the two pieces by 180 degrees. In this processing method, the grinding process can cancel the position degree requirement at two places of the steel sleeve hole compared with the traditional grinding, and there is no need to measure Figure 1 The actual coordinates of the W reference precision positioning hole and record the coordinate values.

[0044] S2. The jig (see embodiment 2) is used to clamp the central transmission frame part for precision positioning hole boring processing, and the boring processing flow is shown in Figure 3 , which specifically includes the following steps:

[0045] S21. Before processing, align the clamping support surface to make the support surface runout not greater than 0.01;

[0046] S22. Align the two steel sleeve hole axes to make the runout not greater than 0.01, and realize angular positioning;

[0047] S23. Find the axial inner hole H reference hole (see Figure 1 )jump is not greater than 0.01;

[0048] S24. Boring precision positioning hole and measurement, this step only needs to measure the part, and each batch of parts only needs to measure the first, middle and last three parts, the measurement content is Figure 1 The position of the two steel sleeve holes relative to the W reference precision positioning hole. From Figure 1 It can be seen that the W reference corresponds to the precision positioning hole, and the precision positioning hole is located at the large end of the central transmission frame.

[0049] Among them, S21, S22 and S23 ensure that the three jump amounts are consistent. When machining the precision positioning hole, the steel sleeve hole is checked by the clamp, and there is no need to find the right or three-coordinate auxiliary measurement. The precision positioning hole can be machined in one step, and it can also meet the technical requirements.

[0050] Example 2

[0051] As shown in Figure 4 and Figure 5 , the clamp mentioned in S2 of example 1 includes a mounting seat 1, which is provided with an axial hole 11 for mounting the part. A through hole is formed in the side wall of the mounting seat 1, and a guide seat 2 is mounted in the through hole. The guide seat 2 is fixed on the mounting seat 1 by screws. The guide seat 2 has an inner hole, and a dial rod 3 is slidably penetrated in the inner hole. One end of the dial rod is provided with a dial gauge (the dial clamp 31 for mounting the dial gauge is shown in Figure 4 , and the other end is provided with a probe 32. The probe 32 and the dial gauge work together. The working linkage of the probe on the dial rod and the dial gauge refers to the structure and principle of the inside diameter lever dial gauge. The dial rod 3 can move axially along the axis of the inner hole of the guide seat 2 so that the end of the dial rod with the probe 32 enters the two steel sleeve holes of the central transmission frame in turn. When the part needs to be placed in the clamp for clamping, as shown in Figure 4 , the dial rod 3 is moved right along the inner hole of the guide seat 2, so that the end of the dial rod with the probe 32 enters the inner hole of the guide seat 2, so that the part can be smoothly placed in the axial hole 11 of the mounting seat. Then the dial rod 3 is moved left along the inner hole of the guide seat 2, so that the end of the dial rod with the probe 32 enters the two steel sleeve holes of the part in turn. The probe 32 detects the axial jump of the two steel sleeve holes and feeds back to the dial gauge.

[0052] As shown in Figure 4 , a groove 33 is formed in the length direction of the dial rod 3, and a screw or pin 34 is arranged at the corresponding position of the groove on the guide seat 2. The end of the screw or pin is embedded in the groove, so as to guide the movement of the dial rod 3 in the guide seat 2 and prevent the dial rod 3 from being offset circumferentially to cause jump error.

[0053] In order to facilitate the parts into the mounting seat and smoothly carry out the stable processing of the precision positioning hole, the mounting seat is further provided with a pressing mechanism 4 for pressing the end face of the part. The pressing mechanism can be a conventional combination of a movable pressing block and a screw.

[0054] The clamp of the embodiment mainly straightens two steel sleeve holes of the part through the surface rod, and then aligns the axial hole of the part. The detailed operation is as follows:

[0055] In order to ensure Figure 1 The position degree of the precision positioning hole of the two steel sleeve holes And The position degree of the precision positioning hole The clamp adopts the surface rod to angularly position the two steel sleeve holes. The surface rod has two functions. Firstly, it is convenient to align the clamp (corresponding to S21 in embodiment 1). When clamping the clamp, the surface rod is straightened to make the clamp and the machine tool workbench form a unified axis, thereby achieving the purpose of angularly positioning the clamp. Specifically, the end of the surface rod with a measuring head is withdrawn from the axial hole of the mounting seat and enters the inner hole of the guide seat. Then, a lever dial gauge is installed on the machine tool spindle, and the dial gauge is set on the outer circle of the surface rod to determine the runout of the outer circle of the surface rod. The runout is not greater than 0.01, and the clamp is straightened. Secondly, it is convenient to align the part. After the part is clamped in place in the mounting seat, the surface rod is moved to the left, the end of the surface rod with a measuring head is inserted into the steel sleeve hole, and the angular reference of the part is aligned with the machine tool coordinates by means of the measuring head on the surface rod and the dial gauge. During operation, the part is adjusted to be in the same straight line by contacting the measuring head with the steel sleeve hole and dragging the surface rod by the dial gauge, so that the error is within 0.01 mm. The function of the surface rod is to confirm whether the axis of the surface rod is consistent with the axes of the two steel sleeve holes, and finally the axes of the machine tool, the clamp and the part are consistent. After that, the pressing mechanism presses the part to process the precision positioning hole, thereby fully ensuring the related position degree requirements.

[0056] The right limit position of the above-mentioned surface rod is sufficient to put the part into the mounting seat. The left limit position is that the end of the surface rod with a measuring head can enter the end of the second steel sleeve hole.

[0057] The processing method can greatly improve the efficiency and shorten the measurement time, and can significantly improve the product quality. According to statistics, it takes 2-3 days to process a batch of parts using the traditional processing method, and the direction is easy to adjust during the processing process, which leads to frequent quality problems. However, now it only takes 4 hours to process a batch, and an average of 10 minutes per part. Because the clamp shown in embodiment 2 is used, the mistake-proofing effect is significantly improved, and the occurrence of unqualified products is fully avoided.

[0058] The machining method has been process solidified, and in view of the machining of more than 200 parts in multiple batches, the process is stable, the machining efficiency is improved, the detection time is greatly reduced, the long-term technical bottleneck is broken through, and the requirements of part production and machining are met.

[0059] It should be noted that: Figure 1 The medium size is only used as an example and does not constitute a limitation on the technical solutions of the present patent.

[0060] Comparative Example 1

[0061] Figure 6 The size of the central transmission frame before the improvement of precise positioning hole machining is shown in the schematic diagram, Figure 7 and Figure 8 The traditional grinding and boring process is shown.

[0062] Figure 7 In the grinding, the measurement requirements are: taking N reference as the plane reference; G-H reference is dragged straight to center; the center A-C reference of the two steel sleeves is dragged straight to the angular direction Y, the actual coordinates of the W reference small hole are measured and the measured values are recorded. Each part in the grinding process needs 100% measurement.

[0063] Figure 8 In the boring, the coordinate value offset position is adjusted according to the coordinate value measured in the grinding process. Each batch in the boring process needs 100% measurement, and each part needs to be measured twice.

[0064] Obviously, the above examples are only examples for clearly illustrating the technical solutions of the present application, and are not a limitation on the embodiments of the present application. For ordinary skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for machining precision positioning holes in the central transmission frame of an aero-engine, wherein the central transmission frame has a steel sleeve hole and an axial inner hole, and a precision positioning hole is opened at the large end of the central transmission frame, the precision positioning hole using the steel sleeve hole as a reference to ensure positional accuracy, characterized in that... Includes the following steps: S1. Grind two steel sleeve holes. Both steel sleeve holes are ground to the required dimensions in one pass. Grind one steel sleeve hole first, rotate the two parts 180 degrees, and then grind the other steel sleeve hole. S2. The central transmission frame part is clamped in a fixture for precision boring of the positioning holes. The boring process includes the following steps: S21. Align the fixture support surface before machining; S22. Align the axes of the two steel sleeve holes for angular positioning; S23. Align the axial inner hole reference; S24. Boring and measuring precision positioning holes; In S21, the fixture support surface is aligned to ensure that the runout of the support surface is no greater than 0.

01. In S22, the axial runout of the two steel sleeve holes is aligned to ensure that it is no greater than 0.

01. In S23, the axial inner hole reference runout is aligned to ensure that it is no greater than 0.

01. In S24, only the first, middle, and last three parts of each batch need to be measured. The fixture mentioned in S2 includes a mounting base with an axial hole for mounting parts. A through hole is opened on the side wall of the mounting base, and a guide seat is installed in the through hole. The guide seat has an inner hole, and a dial indicator is slidably installed in the inner hole. A dial indicator is installed at one end of the dial indicator and a probe is installed at the other end. The dial indicator can move axially along the axis of the inner hole so that the end with the probe enters the two steel sleeve holes of the central transmission frame in sequence. The probe detects the axial runout of the two steel sleeve holes and feeds back to the dial indicator.

2. The method for machining the precision positioning hole position of the central transmission frame of an aero-engine according to claim 1, characterized in that, In S24, the parts only need to be measured once.

3. The method for machining the precision positioning hole position of the central transmission frame of an aero-engine according to claim 1, characterized in that, The mounting base also includes a clamping mechanism that clamps the end face of the part.

4. The method for machining the precision positioning hole position of the central transmission frame of an aero-engine according to claim 1, characterized in that, The steps for aligning the fixture support surface in S21 are as follows: the end of the gauge rod with the probe is withdrawn from the axial hole of the mounting seat, and the runout of the outer circle of the gauge rod is determined so that the runout is no greater than 0.01.

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