A processing method to improve the measurement pass rate of short oblique holes in the housing

Abstract

This invention belongs to the field of machining and discloses a machining method for improving the metrological qualification rate of short oblique holes in housings. The method involves filling a reference hole in a housing part with a low-melting-point alloy, and after solidification, machining a short oblique hole along one side of the reference hole filled with the low-melting-point alloy to create an extension hole connecting the low-melting-point alloy through hole to the short oblique hole in the housing part. A mandrel is inserted into the extension hole to complete the metrological process of the short oblique hole. Finally, the low-melting-point alloy in the reference hole is cleaned to separate it from the housing part. The design of the extension hole serves two purposes: first, it lengthens the short oblique hole, increasing the mating length between the mandrel and the hole, thus reducing metrological errors; second, it provides better guidance for the mandrel, allowing its axis to coincide more closely with the axis of the oblique hole, further reducing metrological errors and effectively improving the metrological qualification rate.

Description

Technical Field

[0001] This invention belongs to the field of machining, specifically to the field of machining aircraft shells, and specifically relates to a machining method for improving the measurement pass rate of short oblique holes in the shell. Background Technology

[0002] In aerospace housing parts, there are structures with short oil passage holes. Due to their short length and slant, these holes are generally referred to as thin-walled oblique holes or short oblique holes. The axis of the oil passage hole has specific positional dimensional requirements, specifically regarding spatial dimensions, the angle with the end face, and the distance from the intersection of the oil passage hole axis and the end face to the center of the reference hole. For housing parts with short oil passage holes, machining is generally performed on a machining center. After the part is clamped and positioned on the machine tool, it is machined using CNC programming. After machining, the positional dimensions, angles, and intersection distances need to be measured on a coordinate measuring machine. Only when the actual measured positional dimensions meet the tolerance requirements can subsequent normal batch production proceed. Typically, this measurement and inspection is accomplished by inserting a mandrel into the machined hole.

[0003] However, during the machining and measurement of housing parts, positional dimension measurement often fails to meet standards. The main reasons for this are: the machined holes are short and angled, resulting in shape and dimensional errors; uneven gaps exist between the hole and the mandrel; and the short hole length reduces the mandrel's guiding ability. Furthermore, after the mandrel is inserted into the hole, its axis cannot perfectly coincide with the hole's axis, causing significant errors and greatly affecting the accuracy of the measurement results, ultimately leading to compromised quality in subsequent mass production. Current solutions involve using a reamer or boring tool to precisely machine the angled holes, improving their shape accuracy; and ensuring better contact between the mandrel's outer diameter and the hole wall, maximizing the alignment of its axis with the hole's axis to minimize adverse effects on the measurement results. However, this method severely impacts machining efficiency, as the short hole and insufficient guiding ability for the measuring mandrel result in a low first-pass yield rate.

[0004] It is evident that with the existing metrological processing method, the axis of the mandrel cannot be completely aligned with the axis of the processed hole after it is inserted into the hole, resulting in a large error and greatly affecting the accuracy of the metrological results. Summary of the Invention

[0005] The purpose of this invention is to provide a processing method that improves the pass rate of measurement of the position dimension of short oblique holes in the shell, so as to solve the technical problem that when using the existing measurement method, the axis of the mandrel cannot be completely coincident with the axis of the processed hole after being inserted into the hole, resulting in large errors and greatly affecting the accuracy of the measurement results.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A processing method for improving the measurement pass rate of short oblique holes in housings includes the following steps:

[0008] The reference holes of the housing parts are filled with a low-melting-point alloy in a molten state;

[0009] After the low-melting-point alloy solidifies, a short oblique hole is machined on the shell part along the side of the reference hole filled with the low-melting-point alloy. The short oblique hole communicates with the through hole opened in the solidified low-melting-point alloy and forms an extended hole.

[0010] Insert the mandrel into the extension hole to measure the dimensions of the short, oblique hole.

[0011] The low-melting-point alloy of the reference hole is cleaned to separate the low-melting-point alloy from the housing parts.

[0012] Furthermore, a 3-5 mm gap is left between the end face of the low-melting-point alloy filling and the top end face of the reference hole.

[0013] Furthermore, the specific steps for machining short, oblique holes in the housing part along one side of the reference hole filled with a low-melting-point alloy are as follows:

[0014] Use a milling cutter to flatten the opening in the solidified low-melting-point alloy;

[0015] Use a center drill to make dots on the flattened end face;

[0016] Drilling is performed using a drill bit to create through holes in the low-melting-point alloy, forming short, oblique holes in the housing parts. The through holes and short, oblique holes communicate with each other to form an extension hole.

[0017] Furthermore, the specific steps of machining short, oblique holes in the housing part along one side of the reference hole filled with a low-melting-point alloy also include:

[0018] After drilling is completed, the machined housing part is removed from the machine tool, and the burrs produced during machining are removed.

[0019] Furthermore, the specific steps of the measurement process for the position and size of the short oblique hole are as follows:

[0020] Insert the selected mandrel into the extension hole;

[0021] The probe is driven to collect points on the reference hole, and then a model of the measurement reference is established in the metrology software;

[0022] The driving probe collects points on the mandrel, and then a cylindrical model is created in the metrology software, wherein the cylindrical model represents the machined hole;

[0023] In the metrology software, the positional dimensions of the cylindrical model relative to the reference are evaluated, and the metrology results are generated;

[0024] The measurement results are compared with the product requirements to determine whether the measurement results are qualified.

[0025] Furthermore, the mandrel with the smallest gap between itself and the hole is selected as the mandrel used for measurement.

[0026] Furthermore, the specific steps for cleaning the low-melting-point alloy of the reference hole to achieve separation between the low-melting-point alloy and the housing parts are as follows:

[0027] The housing parts are heated in boiling water, causing the low-melting-point alloy to melt completely and flow out from the reference hole of the housing parts, thus separating them from the housing parts.

[0028] Furthermore, the low-melting-point alloy is one of indium gallium alloy, gallium indium tin alloy, and Wood's alloy.

[0029] Furthermore, the length of the mandrel is greater than the length of the extension hole.

[0030] Furthermore, CNC programming is used to machine short, oblique holes in the housing parts.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention provides a processing method to improve the metrological qualification rate of short oblique holes in housings. This method utilizes a molten low-melting-point alloy to fill a reference hole in a housing part. After the low-melting-point alloy solidifies, a short oblique hole is machined along one side of the reference hole filled with the low-melting-point alloy to create an extension hole connecting the low-melting-point alloy through hole and the short oblique hole in the housing part. A mandrel is inserted into the extension hole to complete the metrological process of the short oblique hole's position. Finally, the low-melting-point alloy in the reference hole is cleaned to separate it from the housing part. The design of the extension hole serves two purposes: first, it lengthens the short oblique hole, increasing the mating length between the mandrel and the hole, thus reducing metrological errors; second, the extension hole provides better guidance for the mandrel, allowing its axis to coincide more closely with the axis of the oblique hole, further reducing metrological errors and effectively improving the metrological qualification rate.

[0033] Preferably, in this invention, a certain distance (3-5 mm) is reserved between the end face after the low melting point alloy is filled and the top end face of the reference hole. This facilitates the measurement and detection of the position and size of the short oblique hole during the measurement process, ensuring the accuracy and effect of the measurement and detection.

[0034] Preferably, in this invention, the specific steps for machining short oblique holes along one side of the reference hole filled with low-melting-point alloy include squaring the hole opening, marking points, drilling, etc. The above steps ensure the accuracy and stability of the machining process, which is beneficial to improving machining efficiency and quality.

[0035] More preferably, in this invention, after drilling is completed, the housing part is removed from the machine tool and the burrs are removed. This step reduces errors and defects generated during the processing and further improves the processing quality.

[0036] Preferably, in this invention, the measurement process for the position size of the short oblique hole includes inserting a mandrel, taking data points, establishing a model, and evaluating the position size. The above steps ensure the accuracy and reliability of the measurement process, which is beneficial for accurately determining whether the position size of the short oblique hole in the shell is qualified.

[0037] More preferably, in this invention, the mandrel with the smallest gap between itself and the hole is selected as the mandrel used for measurement, which reduces the error caused by the gap between the mandrel and the hole and improves the accuracy of measurement.

[0038] Preferably, in this invention, the low-melting-point alloy is completely melted and flows out from the reference hole by heating the shell part, thereby achieving separation between the alloy and the shell part. This step is simple and effective, avoiding subsequent processing problems caused by alloy residue.

[0039] Preferably, in this invention, the low-melting-point alloy can be one of indium gallium alloy, gallium indium tin alloy, and Wood's alloy. These materials have good fluidity and low melting point, are easy to fill and clean, and are beneficial to improving processing efficiency and quality.

[0040] Preferably, in this invention, the length of the mandrel is ensured to be greater than the length of the extension hole, so that the mandrel can be fully inserted into the short oblique hole and the through hole opened by the low melting point alloy, thereby accurately measuring the position and size.

[0041] Preferably, in this invention, CNC programming is used to process short oblique holes in the housing parts, which improves the automation and accuracy of the processing, reduces errors caused by human factors, and helps to improve processing efficiency and quality. Attached Figure Description

[0042] Figure 1 A schematic diagram of a thin-walled oblique hole structure for a housing part provided in an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the pre-drilling leveling provided in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the mandrel metering provided in an embodiment of the present invention;

[0045] Figure 4 A schematic diagram showing the offset between the mandrel and the inclined hole axis caused by the gap provided in an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of low-melting-point alloy filling before machining the oblique hole, provided in an embodiment of the present invention.

[0047] Figure 6 This is a schematic diagram of the processing and metering after low-melting-point filling provided in an embodiment of the present invention;

[0048] Figure 7 A flowchart illustrating a processing method for improving the measurement pass rate of short oblique holes in a housing, provided as an embodiment of the present invention.

[0049] Figure label:

[0050] Mandrel-1; Hole axis-2; Low melting point alloy-3; Short oblique hole-4. Detailed Implementation

[0051] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0052] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0053] Example

[0054] As mentioned in the background section, existing aircraft housing parts include a type such as Figure 1The short oil passage hole structure shown is generally referred to as a thin-walled oblique hole, or short oblique hole 4, due to its short length and slant. The hole axis 2 of the short oblique hole 4 has specific positional dimensional requirements, specifically regarding spatial dimensions, the angle α with the end face, and the distance L from the intersection of the oil passage hole axis and the end face to the center of the reference hole. For shell parts with short oil passage holes, machining is generally performed on a machining center. After the part is clamped and positioned on the machine tool, it is machined using CNC programming. After machining, the positional dimensions, angle α, and intersection distance L need to be measured on a coordinate measuring machine. Only when the actual values ​​of the measured positional dimensions meet the tolerance requirements can subsequent normal batch production proceed. Typically, a mandrel is inserted into the machined hole to complete the measurement and inspection. However, due to the short length of the machined hole and its inclined shape, there are always uneven gaps between the hole and the mandrel, resulting in insufficient guidance for the mandrel. After the mandrel is inserted into the hole, its axis cannot be perfectly aligned with the axis of the machined hole, causing significant errors. This greatly affects the accuracy of the measurement results, leading to compromised quality in subsequent mass production. Current solutions to these problems involve using a reamer or boring tool to precisely machine the inclined hole, improving its shape accuracy. This also improves the fit between the mandrel's outer diameter and the hole wall, ensuring its axis aligns as closely as possible with the hole's axis, thus minimizing the negative impact on the measurement results. However, this method severely impacts processing efficiency. The short machined hole's insufficient guidance for the measuring mandrel results in a large deviation between the measurement angle and the actual angle, leading to a still low first-pass yield.

[0055] To address the aforementioned issues, this embodiment provides a processing method for improving the measurement pass rate of short oblique holes in the housing. This method is mainly applied to the measurement and processing of holes with diameters of 2.5–5 mm and hole lengths of less than 10 mm. By effectively extending the short oblique holes, this method ensures that the measurement results of the position dimensions of the short oblique oil passage holes after processing are stable and reliable, significantly improving the first-time measurement pass rate and effectively increasing production efficiency.

[0056] like Figure 7 As shown, this embodiment provides a processing method to improve the measurement pass rate of short oblique holes in the housing, including:

[0057] The reference holes of the housing parts are filled with a low-melting-point alloy 3 in a molten state.

[0058] After the low-melting-point alloy 3 solidifies, a short oblique hole is machined on the shell part along the reference hole filled with the low-melting-point alloy. The short oblique hole 4 communicates with the through hole opened in the solidified low-melting-point alloy 3 and forms an extended hole.

[0059] Insert the mandrel 1 into the extension hole to measure the position of the short, oblique hole.

[0060] The low-melting-point alloy of the reference hole is cleaned to separate the low-melting-point alloy from the housing parts.

[0061] To provide a more detailed description of the processing steps provided in this embodiment, the specific steps include:

[0062] Step 1: As Figure 5 As shown, after the low-melting-point alloy is melted, it is poured into the reference hole (large hole in the figure) of the shell part to fill the reference hole. The 3-5mm range at the opening of the reference hole is not filled. That is, a certain distance is reserved between the end face after the low-melting-point alloy is filled and the top end face of the reference hole. This facilitates the measurement and detection of the position and size of the short and small oblique hole during the measurement process, ensuring the accuracy and effect of the measurement and detection.

[0063] In this embodiment, the low-melting-point alloy is one of indium gallium alloy, gallium indium tin alloy and Wood's alloy, or it can be a Bi-based low-melting-point alloy composed of four elements: bismuth (Bi), lead (Pb), tin (Sn) and antimony (Sb), with a melting point of 75 to 90°C.

[0064] Step Two: After the poured low-melting-point alloy cools and solidifies, the shell part is clamped onto a machining center and machining begins using CNC programming; for example... Figure 2 As shown, the specific steps are as follows:

[0065] (1) First, use a milling cutter to flatten the hole opening;

[0066] (2) Use a center drill to make dots on the flattened end face;

[0067] (3) Then use a drill bit to drill a hole;

[0068] (4) The finished housing parts are removed from the machine tool and the burrs generated during processing are removed;

[0069] After the housing parts are machined, the positional dimensions, including the included angle α and the distance L between the intersection points, need to be measured on a coordinate measuring machine. Only when the actual values ​​of the measured positional dimensions meet the tolerance requirements can subsequent normal batch production be carried out.

[0070] In this embodiment, a through hole is drilled in the low melting point alloy, and then drilling continues in the thin wall between the two reference holes to drill a short oblique hole. It can be seen that the through hole is an extension of the short oblique hole, and the two together form an extended hole.

[0071] Step 3: Place the part on a coordinate measuring machine to measure and check the position and dimensions of the short, oblique hole 4, such as... Figure 5 and Figure 6 As shown, the specific steps are as follows:

[0072] (1) Select mandrel 1 and insert a mandrel of appropriate size into the hole to be measured. The mandrel used for measurement is a standard part, and its outer diameter is generally grouped in intervals of 0.01 mm. In this process, multiple attempts are generally required to ensure that the inner hole of the mandrel is inserted into the hole and that the gap between the mandrel and the hole is minimized.

[0073] (2) During measurement, first drive the probe to collect points on the reference hole (and surface), and then establish a model of the measurement reference (reference hole and orifice plane) in the measurement software.

[0074] (3) Then, drive the probe to collect points on the mandrel, and then build a cylindrical model in the metrology software. This cylindrical model represents the machining hole.

[0075] (4) In the measurement software, evaluate the position and dimensions (including angle) of the machined hole (short oblique hole 4) relative to the reference and generate the measurement results.

[0076] (5) Compare the measurement results with the technical requirements to determine whether the measurement results are qualified.

[0077] It should be noted here that... Figure 3 and Figure 4 This is a conventional measurement method. Figure 5 and Figure 6 The measurement method mentioned in this processing method is adopted, that is, the low melting point alloy 1 is filled in the reference hole, which realizes the extension of the short oblique hole 4, which plays a good guiding role for the mandrel 1 and increases the fitting length between the hole and the mandrel 1; so that the hole axis 2 basically coincides with the center line of the mandrel 1, thereby effectively reducing the measurement error and ensuring the measurement and subsequent batch processing accuracy.

[0078] Step 4: After the measurement is completed, the shell part is placed in boiling water and heated to completely melt the low melting point alloy 1, which then flows out of the shell part and separates from it.

[0079] In this embodiment, the essential function is to extend the length of the machined oblique hole. This allows the machined hole to better guide the mandrel after it is inserted into the hole during measurement, ensuring that the mandrel's axis coincides more closely with the axis of the machined hole. This reduces measurement errors and effectively improves the measurement pass rate. Therefore, the machining method provided in this embodiment for improving the measurement pass rate of short oblique holes in the housing can significantly eliminate measurement failures caused by short hole sections and poor guidance. This method significantly improves the machining measurement pass rate and increases production efficiency.

[0080] In summary, this embodiment provides a processing method to improve the metrological qualification rate of short oblique holes in the housing. Compared with existing metrological processing methods, it has the following advantages:

[0081] This invention provides an innovative metrological processing method that significantly improves the metrological qualification rate of short, oblique holes in housings. This method utilizes a molten low-melting-point alloy to fill the reference hole in the housing part, and after the alloy solidifies, an extension hole communicating with the short, oblique hole is machined along one side. This effectively solves the difficulties in machining and measuring short, oblique holes. The design of the extension hole not only increases the mating length between the mandrel and the oblique hole, improving metrological accuracy, but also provides good guidance, allowing the mandrel's axis to coincide more closely with the axis of the oblique hole, further reducing metrological errors. Furthermore, this method employs several optimized measures during machining and metrology, such as reserving a certain distance for the low-melting-point alloy end face, precise machining steps, deburring, accurate metrological procedures, selecting a mandrel with minimal clearance, a simple and effective alloy cleaning method, high-quality low-melting-point alloy material, ensuring the mandrel length is greater than the extension hole, and using CNC programming machining. These measures collectively improve the accuracy and stability of machining, reduce errors and defects, and ensure the reliability and accuracy of the metrological results. Therefore, this invention not only improves the measurement qualification rate of the short oblique hole position size of the shell, but also improves the processing efficiency and quality, providing strong technical support and guarantee for the processing and manufacturing of aerospace shells.

[0082] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0083] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and the disclosed concept of the present invention, should be covered within the scope of protection of the present invention.

[0084] The further detailed description provided in this publication should not be construed as limiting the specific embodiments of the present invention to this extent. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered as falling within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A processing method for improving the measurement qualification rate of the position dimension of a short and inclined hole in a shell, characterized in that, The method comprises the following steps: Filling the reference hole of the shell part with low-melting alloy in a molten state; After the low-melting alloy solidifies, a short and small inclined hole is processed on the shell part along one side of the reference hole filled with the low-melting alloy, wherein the short and small inclined hole is communicated with a through hole formed in the solidified low-melting alloy and constitutes an extended hole; Inserting a core rod into the extended hole to perform a measurement process of the position and size of the short and small inclined hole; Cleaning the low-melting alloy of the reference hole to separate the low-melting alloy from the shell part; The specific steps of processing the short and small inclined hole on the shell part along one side of the reference hole filled with the low-melting alloy are as follows: Using a milling cutter to flatten the hole mouth on the solidified low-melting alloy; Using a center drill to punch a point on the flattened end face; Using a drill bit to perform drilling to form a through hole in the low-melting alloy and a short and small inclined hole in the shell part, and the through hole is communicated with the short and small inclined hole and constitutes an extended hole; The specific steps of the measurement process of the position and size of the short and small inclined hole are as follows: Inserting the selected core rod into the extended hole; Driving the probe to sample points on the reference hole, and then establishing a model of the measurement reference in the measurement software; Driving the probe to sample points on the core rod, and then establishing a cylindrical model in the measurement software, wherein the cylindrical model represents the processed hole; In the measurement software, evaluating the position and size of the cylindrical model to the reference, and outputting the measurement result; Comparing the measurement result with the product requirement to determine whether the measurement result is qualified.

2. The machining method for improving the pass rate of the position dimension measurement of a short and small inclined hole of a housing according to claim 1, characterized in that, The end face after the low-melting alloy filling and the top end face of the reference hole are reserved by 3-5 mm.

3. The method of claim 1, wherein the method further comprises: The specific steps of processing the short and small inclined hole on the shell part along one side of the reference hole filled with the low-melting alloy further comprise: After the drilling is completed, the processed shell part is taken off from the machine tool, and burrs generated in the processing are removed.

4. The method of claim 1, wherein the method further comprises: The core rod with the smallest gap between the hole is selected as the core rod for measurement.

5. The method of claim 1, wherein the method further comprises: The specific steps of cleaning the low-melting alloy of the reference hole to separate the low-melting alloy from the shell part are as follows: The shell part is heated in boiling water, so that the low-melting alloy is completely melted and flows out of the reference hole of the shell part, and the separation from the shell part is realized.

6. The method of claim 1, wherein the method further comprises: The low-melting alloy uses one of indium-gallium alloy, gallium-indium-tin alloy and Wood's metal.

7. The method of claim 1, wherein the method further comprises: The length of the core rod is greater than the length of the extended hole.

8. The method of claim 1, wherein the method further comprises: The shell part is processed with a short and small inclined hole by numerical control programming.

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