Machining method for improving position dimension metering qualification rate of short and small inclined holes of shell

Abstract

The invention belongs to the field of machining, and discloses a machining method for improving the position size metering qualification rate of a short and small inclined hole of a shell, which comprises the following steps: filling a reference hole of a shell part with a low-melting-point alloy, and performing short and small inclined hole machining on the shell part along one side of the reference hole filled with the low-melting-point alloy after solidification, a low-melting-point alloy through hole and an extension hole communicated with a short and small inclined hole of the shell part are formed, a core rod is inserted into the extension hole to complete the metering process of the position size of the short and small inclined hole, and finally the low-melting-point alloy of the reference hole is cleaned to achieve separation of the low-melting-point alloy and the shell part; the machining design of the extension hole has two effects that firstly, the short and small inclined hole is lengthened and extended, so that the matching length of the core rod and the short and small inclined hole is increased, and the metering error is reduced; secondly, the core rod can be well guided, and the axis of the core rod can coincide with the axis of the inclined hole to a greater extent; the metering error is further reduced, and the metering qualification rate is effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of mechanical processing, in particular to the field of mechanical processing of aviation shells, and specifically relates to a processing method for improving the metrological pass rate of the position size of a short inclined hole of a shell. Background Art

[0002] Aviation shell parts include short oil hole structures. Since the oil hole is short and inclined, it is generally called a thin-walled inclined hole or a short inclined hole. The axis of the oil hole has certain positional dimension requirements, including the spatial dimension, the angle with the end face, and the distance between the intersection of the axis of the oil hole and the end face and the center of the reference hole. Shell parts with short oil holes are generally processed on a machining center. After the parts are clamped on the machine tool for positioning, they are processed using CNC programming. The processed parts need to be measured on a three-coordinate measuring instrument for the positional dimension angle and the intersection distance. The actual value of the measured positional dimension must meet the tolerance requirements before subsequent normal batch processing and production can be carried out. Usually, the measurement and inspection of the processing is completed by inserting a core rod in the processing hole.

[0003] However, in the process of machining and measuring shell parts, the position dimension measurement inspection often fails. The main reasons are: the machining hole is short and it is an inclined hole. There are errors in its shape and size. There is always an uneven gap between the hole and the mandrel. In addition, the hole length is small and the mandrel is not sufficiently guided. After the mandrel is inserted into the hole, its axis cannot completely coincide with the axis of the machining hole, resulting in a large error, which greatly affects the accuracy of the measurement results, and then the quality of subsequent mass production of products cannot be guaranteed. In view of the above problems, the existing solution is to increase the use of reamer or boring tool when machining the inclined hole, perform precision machining on the inclined hole, and improve the shape accuracy of the hole; after the mandrel is inserted into the hole, the fit between the outer circle of the mandrel and the wall of the inclined hole is improved, and its axis is as close to the axis of the hole as possible, reducing the adverse effects on the measurement results; however, this method seriously affects the machining efficiency. Due to the short machining hole, the mandrel is not sufficiently guided, and the one-time measurement pass rate is still low.

[0004] It can be seen that with the existing measurement and processing method, after the core rod is inserted into the hole, its axis cannot completely coincide with the axis of the processed hole, resulting in a large error, which greatly affects the accuracy of the measurement result. Summary of the invention

[0005] The purpose of the present invention is to provide a processing method for improving the qualified rate of the measurement of the position size of the short inclined hole of the shell, so as to solve the technical problem that when using the existing measurement method, after the core rod is inserted into the hole, its axis cannot completely coincide with the axis of the processed hole, resulting in large errors and greatly affecting the accuracy of the measurement results.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A processing method for improving the metrological pass rate of the position size of a short and small inclined hole of a shell comprises the following steps: The reference hole of the shell part is filled with a low melting point alloy in a molten state; After the low melting point alloy solidifies, a short oblique hole is processed on the shell part along one side of the reference hole filled with the low melting point alloy, wherein the short oblique hole is connected with the through hole opened by the solidified low melting point alloy to form an extended hole; Insert the mandrel into the extended hole to measure the position and size of the short and small inclined hole; The low melting point alloy of the reference hole is cleaned to achieve separation between the low melting point alloy and the shell part.

[0007] Furthermore, a gap of 3 to 5 mm is reserved between the end surface after being filled with the low melting point alloy and the top end surface of the reference hole.

[0008] Furthermore, the specific steps of machining a short oblique hole on the shell part along one side of the reference hole filled with the low melting point alloy are as follows: Use a milling cutter to level the hole on the solidified low-melting-point alloy; Use a center drill to make a point on the leveled end surface; A drill is used to drill a hole, a through hole is opened in the low melting point alloy, and a short inclined hole is formed in the shell part. The through hole is connected with the short inclined hole to form an extended hole.

[0009] Furthermore, the specific step of machining a short oblique hole on the shell part along one side of the reference hole filled with the low melting point alloy also includes: After drilling is completed, the machined shell parts are removed from the machine tool and the burrs generated by the machining are removed.

[0010] Furthermore, the specific steps of the measurement process of the position size of the short and small inclined hole are as follows: Insert the selected mandrel into the extended hole; Drive the probe to pick points on the reference hole, and then build a model of the measurement reference in the metrology software; Driving the probe to pick points on the mandrel, and then establishing a cylindrical model in the metrology software, wherein the cylindrical model represents the processed hole; In the metrology software, evaluate the position and size of the cylinder model relative to the benchmark and issue the metrology results; Compare the measurement results with product requirements to determine whether the measurement results are qualified.

[0011] Furthermore, a core rod with the smallest gap between the core rod and the hole is selected as the core rod used for measurement.

[0012] Furthermore, the specific steps of cleaning the low melting point alloy in the reference hole to separate the low melting point alloy from the housing part are as follows: The shell part is placed in boiling water for heating, so that the low melting point alloy is completely melted and flows out from the reference hole of the shell part, thereby being separated from the shell part.

[0013] Furthermore, the low melting point alloy is one of Indium Gallium alloy, Gallium Indium Tin alloy and Wood's alloy.

[0014] Furthermore, the length of the core rod is greater than the length of the extension hole.

[0015] Furthermore, numerical control programming is used to process short and small oblique holes in the shell parts.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a processing method for improving the metrological pass rate of the position size of a short and small inclined hole of a shell. The method uses a molten low-melting-point alloy to fill a reference hole of a shell part. After the low-melting-point alloy solidifies, the shell part is processed for a short and small inclined hole along one side of the reference hole filled with the low-melting-point alloy to open an extended hole connected to the short and small inclined hole of the shell part through a low-melting-point alloy through hole. The measurement process of the position size of the short and small inclined hole is completed by inserting a core rod into the extended hole. Finally, the low-melting-point alloy in the reference hole is cleaned to separate the low-melting-point alloy from the shell part. The processing design of the extended hole plays two roles: first, the short and small inclined hole is lengthened and extended, thereby increasing the matching length of the core rod and the short and small inclined hole and reducing the metrological error; second, the extended hole can play a better guiding role for the core rod, and the axis of the core rod can coincide with the axis of the inclined hole to a greater extent; the metrological error is further reduced, and the metrological pass rate is effectively improved.

[0017] Preferably, in the present invention, a certain distance (3 to 5 mm) is reserved between the end face after filling with the low-melting-point alloy and the top end face of the reference hole. This facilitates measurement and detection of the position size of the short inclined hole during the measurement process, thereby ensuring the accuracy and measurement effect of the measurement and detection.

[0018] Preferably, in the present invention, the specific steps of machining a short inclined hole along one side of a reference hole filled with a low-melting-point alloy include leveling the hole mouth, dotting, drilling, etc. The above steps ensure the accuracy and stability of the machining process, which is conducive to improving machining efficiency and quality.

[0019] Further preferably, in the present invention, after the drilling is completed, the shell part is removed from the machine tool and the burrs are removed. This step reduces the errors and defects generated during the processing and further improves the processing quality.

[0020] Preferably, in the present invention, the measurement process of the position size of the short inclined hole includes inserting a core rod, sampling points, establishing a model, evaluating the position size, etc. The above steps ensure the accuracy and reliability of the measurement process, which is conducive to accurately judging whether the position size of the short inclined hole of the shell is qualified.

[0021] Further preferably, in the present invention, a mandrel with the smallest gap with the hole is selected as the mandrel used for measurement, thereby reducing the error caused by the gap between the mandrel and the hole and improving the accuracy of measurement.

[0022] Preferably, in the present invention, the low-melting-point alloy is completely melted by heating the shell part and flows out from the reference hole, thereby achieving separation between the alloy and the shell part. This step is simple and effective, and avoids subsequent processing problems caused by alloy residue.

[0023] Preferably, in the present invention, the material of 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 conducive to improving processing efficiency and quality.

[0024] Preferably, in the present invention, the length of the core rod is ensured to be greater than the length of the extended hole, so that the core rod can be fully inserted into the short inclined hole and the through hole opened by the low melting point alloy, thereby accurately measuring the position size.

[0025] Preferably, in the present invention, numerical control programming is used to process short and small oblique holes in the shell parts, which improves the automation and accuracy of the processing, reduces errors caused by human factors, and is conducive to improving processing efficiency and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a thin-walled oblique hole structure of a housing part provided in an embodiment of the present invention; Figure 2 A schematic diagram of leveling before drilling provided by an embodiment of the present invention; Figure 3 A schematic diagram of core-insertion rod metering provided in an embodiment of the present invention; Figure 4 A schematic diagram of the offset between the core rod and the oblique hole axis caused by the gap provided in an embodiment of the present invention; Figure 5 A schematic diagram of filling a low melting point alloy before machining an inclined hole provided by an embodiment of the present invention; Figure 6 A schematic diagram of processing and metering after low-melting-point filling provided by an embodiment of the present invention; Figure 7 A flow chart of a processing method for improving the metrological pass rate of the position size of a short oblique hole of a shell provided in an embodiment of the present invention.

[0027] Reference numerals: Core rod-1; hole axis-2; low melting point alloy-3; short inclined hole-4. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0030] Example As mentioned in the background technology, the existing aviation shell parts include a Figure 1The short oil hole structure shown is generally also called a thin-walled inclined hole, or a short inclined hole 4, because the oil hole is short and inclined. The hole axis 2 of the short inclined hole 4 has certain positional dimension requirements, specifically the spatial dimension, the angle α with the end face, and the distance between the intersection of the oil hole axis and the end face and the center of the reference hole L. For shell parts with short oil holes, they are generally processed on a machining center. After the parts are clamped on the machine tool for positioning, they are processed using CNC programming. The parts after processing need to be measured on a three-coordinate measuring instrument for the positional dimension angle α and the intersection distance L. The actual value of the measured positional dimension meets the tolerance requirements before subsequent normal batch processing and production can be carried out. Usually, the measurement and inspection of the processing is completed by inserting a core rod in the processing hole. However, due to the short length of the processed hole and the existence of shape and size errors, there is always an uneven gap between the hole and the mandrel, and the small length of the hole does not provide sufficient guidance for the mandrel. After the mandrel is inserted into the hole, its axis cannot completely coincide with the axis of the processed hole, resulting in a large error, which greatly affects the accuracy of the measurement results, and thus the quality of subsequent mass production of products cannot be guaranteed. In response to the above problems, the existing solution is to increase the use of reamer or boring tool when processing the inclined hole, perform precision processing on the inclined hole, and improve the shape accuracy of the hole; after the mandrel is inserted into the hole, the fit between the outer circle of the mandrel and the wall of the inclined hole is improved, and its axis is as close to the axis of the hole as possible, reducing the adverse effects on the measurement results; however, this method seriously affects the processing efficiency. Due to the short processing hole, the mandrel is not sufficiently guided, and the measurement angle deviates greatly from the actual angle, resulting in a low one-time measurement pass rate.

[0031] In order to solve the above problems, the present embodiment provides a processing method for improving the qualified rate of measurement of the position size of short and small inclined holes in a shell, which is mainly used for the measurement and processing of holes with a diameter of 2.5 to 5 mm and a physical length of the hole less than 10 mm; the present method effectively extends the short and small inclined holes, so that the measurement results of the position size of the short inclined oil circuit holes after processing are stable and reliable, and the qualified rate of one-time measurement is greatly improved, which can effectively improve production efficiency.

[0032] like Figure 7 As shown, this embodiment provides a processing method for improving the metrological pass rate of the position size of a short and small inclined hole of a housing, comprising: The reference hole of the shell part is filled with the low melting point alloy 3 in a molten state; After the low melting point alloy 3 solidifies, a short oblique hole is processed on the shell part along one side of the reference hole filled with the low melting point alloy, wherein the short oblique hole 4 is connected with the through hole opened by the solidified low melting point alloy 3 to form an extended hole; Insert the mandrel 1 into the elongated hole to measure the position and size of the short and small inclined hole; The low melting point alloy of the reference hole is cleaned to achieve separation between the low melting point alloy and the shell part.

[0033] In order to introduce the processing steps provided in this embodiment in more detail, the specific steps include: Step 1: If Figure 5 As shown, after the low-melting-point alloy is melted, it is poured into the reference hole of the shell part (the large hole in the figure) to fill the part reference hole. The range of 3 to 5 mm within the reference hole mouth 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, so as to facilitate the measurement and detection of the position size of the short inclined hole during the measurement process, thereby ensuring the accuracy and measurement effect of the measurement and detection.

[0034] In this embodiment, the low melting point alloy is one of indium gallium alloy, gallium indium tin alloy and Wood's alloy, and can also be a Bi-based low melting point alloy configured with four elements of bismuth (Bi), lead (Pb), tin (Sn) and antimony (Sb), with a melting point of 75 to 90°C.

[0035] Step 2: After the poured low melting point alloy cools and solidifies, the shell parts are clamped on the machining center machine tool and normal processing is started using CNC programming; Figure 2 As shown, the specific steps are as follows: (1) First use a milling cutter to level the hole; (2) Use a center drill to make a point on the leveled end surface; (3) Then use the drill bit to drill holes; (4) The machined shell parts are removed from the machine tool and the burrs generated by the machining are removed; After the shell parts are processed, the position dimension angle α and the intersection distance L need to be measured on a three-coordinate measuring machine. The actual values ​​of the measured position dimensions must meet the tolerance requirements before subsequent normal batch processing and production can be carried out.

[0036] In this embodiment, a through hole is drilled in the low melting point alloy, and then drilling is continued in the thin wall between the two reference holes to drill a short inclined hole. It can be seen that the through hole is an extension of the short inclined hole, and the two constitute an extended hole.

[0037] Step 3: Place the part on a three-coordinate measuring machine to measure and check the position and size of the short inclined hole 4. Figure 5 and Figure 6 As shown, the specific steps are as follows: (1) Select the mandrel 1 and insert the mandrel of appropriate size into the hole to be measured. The mandrel used for measurement is a standard part, and its outer diameter size is generally grouped at 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.

[0038] (2) During measurement, first drive the probe to sample points on the reference hole (and surface), and then create a model of the measurement reference (reference hole and orifice plane) in the metrology software.

[0039] (3) Then, drive the probe to pick points on the core rod, and then create a cylindrical model in the metrology software. This cylindrical model represents the processed hole.

[0040] (4) In the metrology software, evaluate the position and dimensions (including angle) of the processed hole (short inclined hole 4) relative to the reference and provide the metrology results.

[0041] (5) Compare the measurement results with the technical requirements to determine whether they are qualified.

[0042] It should be noted here that Figure 3 and Figure 4 For conventional measurement methods, Figure 5 and Figure 6 The metering method mentioned in the processing method is adopted, that is, a low-melting-point alloy 1 is filled in the reference hole, the short inclined hole 4 is extended, a good guiding effect is played on the core rod 1 and the matching length between the hole and the core rod 1 is increased; the hole axis 2 is basically coincident with the center line of the core rod 1, thereby effectively reducing the metering error and ensuring the metering and subsequent batch processing accuracy.

[0043] Step 4: After the metering is completed, the shell part is placed in boiling water for heating, so that the low-melting-point alloy 1 is completely melted, flows out of the shell part, and is separated from the shell part.

[0044] In this embodiment, its essential function is to lengthen and extend the length of the processed inclined hole, so that when measuring, after the mandrel is inserted into the hole, the processed hole can play a better guiding role for the mandrel, and the axis of the mandrel can also coincide with the axis of the processed hole to a better extent. The error during measurement is reduced, and the measurement pass rate is effectively improved. It can be seen that the processing method provided by this embodiment to improve the measurement pass rate of the position size of the short inclined hole of the shell can significantly eliminate the measurement failure caused by the short physical part of the hole and poor guidance; the use of this method significantly improves the processing measurement pass rate and improves production efficiency.

[0045] In summary, this embodiment provides a processing method for improving the metrological pass rate of the position size of the short and small inclined hole of the housing, which has the following advantages compared with the existing metrological processing method: The present invention provides an innovative metrological processing method, which significantly improves the metrological qualification rate of the position size of the short and small inclined hole of the shell. The method uses a low-melting-point alloy in a molten state to fill the reference hole of the shell part, and after the alloy solidifies, an extended hole connected to the short and small inclined hole is processed along one side thereof, which effectively solves the problem in the processing and measurement of the short and small inclined hole; the design of the extended hole not only increases the matching length of the mandrel and the inclined hole, improves the measurement accuracy, but also plays a good guiding role, so that the axis of the mandrel can coincide with the axis of the inclined hole to a greater extent, further reducing the measurement error. In addition, the method adopts a number of preferred measures in the processing and measurement process, such as reserving a certain distance of the low-melting-point alloy end face, precise processing steps, removing burrs, accurate measurement process, selecting a mandrel with the minimum gap, a simple and effective alloy cleaning method, high-quality low-melting-point alloy material, ensuring that the mandrel length is greater than the extended hole, and using CNC programming processing, etc. These measures jointly improve the accuracy and stability of the processing, reduce errors and defects, and ensure the reliability and accuracy of the measurement results. Therefore, the present invention not only improves the metrological qualification rate of the position size of the short and small inclined holes of the shell, but also improves the processing efficiency and quality, and provides powerful technical support and guarantee for the processing and manufacturing of aerospace shells.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0047] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and the disclosed concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0048] The further detailed description made in the disclosure cannot be used to determine that the specific implementation modes of the present invention are limited to these. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention determined by the submitted claims.

Claims

1. A processing method for improving the metrological qualification rate of the position size of the short and small inclined holes of a housing, characterized in that: The steps include: The reference hole of the shell part is filled with a low melting point alloy in a molten state; After the low melting point alloy solidifies, a short oblique hole is processed on the shell part along one side of the reference hole filled with the low melting point alloy, wherein the short oblique hole is connected with the through hole opened by the solidified low melting point alloy to form an extended hole; Insert the mandrel into the extended hole to measure the position and size of the short and small inclined hole; The low melting point alloy of the reference hole is cleaned to achieve separation between the low melting point alloy and the shell part.

2. The processing method for improving the metrological pass rate of the short and small inclined holes of a housing according to claim 1 is characterized in that: There is a 3 to 5 mm gap between the end face after being filled with the low melting point alloy and the top end face of the reference hole.

3. The processing method for improving the metrological pass rate of the short and small inclined holes of a housing according to claim 1 is characterized in that: The specific steps of machining a short oblique hole on the shell part along one side of the reference hole filled with the low melting point alloy are as follows: Use a milling cutter to level the hole on the solidified low-melting-point alloy; Use a center drill to make a point on the leveled end surface; A drill is used to drill a hole, a through hole is opened in the low melting point alloy, and a short inclined hole is formed in the shell part. The through hole is connected with the short inclined hole to form an extended hole.

4. The processing method for improving the metrological pass rate of the short and small inclined holes of a housing according to claim 3 is characterized in that: The specific step of machining a short oblique hole on the shell part along one side of the reference hole filled with the low melting point alloy also includes: After drilling is completed, the machined shell parts are removed from the machine tool and the burrs generated by the machining are removed.

5. The processing method for improving the metrological pass rate of the position size of the short and small inclined holes of the housing according to claim 1 is characterized in that: The specific steps of the measurement process of the short and small inclined hole position size are as follows: Insert the selected mandrel into the extended hole; Drive the probe to pick points on the reference hole, and then build a model of the measurement reference in the metrology software; Driving the probe to pick points on the mandrel, and then establishing a cylindrical model in the metrology software, wherein the cylindrical model represents the processed hole; In the metrology software, evaluate the position and size of the cylinder model relative to the benchmark and issue the metrology results; Compare the measurement results with product requirements to determine whether the measurement results are qualified.

6. The processing method for improving the metrological pass rate of the short and small inclined holes of a housing according to claim 5 is characterized in that: The mandrel with the smallest gap with the hole is selected as the mandrel used for measurement.

7. The processing method for improving the metrological pass rate of the position size of the short and small inclined holes of the housing according to claim 1 is characterized in that: The specific steps of cleaning the low melting point alloy of the reference hole to separate the low melting point alloy from the housing part are as follows: The shell part is placed in boiling water for heating, so that the low melting point alloy is completely melted and flows out from the reference hole of the shell part, thereby being separated from the shell part.

8. The processing method for improving the metrological pass rate of the short and small inclined holes of a housing according to claim 1 is characterized in that: The low melting point alloy is one of an indium gallium alloy, a gallium indium tin alloy and a Wood's alloy.

9. The processing method for improving the metrological pass rate of the position size of the short and small inclined holes of the housing according to claim 1 is characterized in that: The length of the core rod is greater than the length of the elongated hole.

10. The processing method for improving the metrological pass rate of the position size of the short and small inclined holes of the housing according to claim 1 is characterized in that: CNC programming is used to process short and small oblique holes in shell parts.

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