Special-shaped part cantilever hole machining method

Abstract

The invention discloses a method for processing a cantilever hole of a special-shaped part, which is characterized in that a positioning mandrel which is processed according to the characteristics of the cantilever hole of the special-shaped part and has expansion and positioning functions is matched with a conical bolt, and during processing, the clamping section of the positioning mandrel is firstly arranged on a three-jaw chuck of a lathe, and a dial indicator or a dial indicator is used for aligning a positioning surface; the radial run-out of the special-shaped part is ensured not to be greater than the form and position required tolerance, then the special-shaped part to be machined with shafting hole machining at one end completed is installed on the positioning mandrel, the conical bolt is tightened to tightly support the special-shaped part, finally, the elements to be machined of the special-shaped part are machined, and the related size of the special-shaped part is ensured; and checking the run-out value of the inner hole of the processed shafting hole by using a dial indicator or a dial indicator. After the special-shaped part is machined, hole systems at the two ends are metered through three coordinates, and the coaxiality of the hole systems at the two ends is checked. According to the invention, the hole system coaxiality requirement of twice positioning, clamping and processing can be effectively ensured.

Description

Technical Field

[0001] The invention belongs to the field of mechanical processing, and in particular relates to a method for positioning and clamping a cantilever hole of a special-shaped part. Background Art

[0002] like Figure 1 The figure shows a valve housing part, which is a typical special-shaped structural part (hereinafter referred to as a special-shaped part). Special-shaped parts are one of the common structural features of aviation products. Such parts are limited by the space and weight of airborne equipment, and the design of the parts' external structure is relatively complex. The wall thickness is relatively thin, and the irregular shape makes it difficult to process, position and clamp the parts. Moreover, such parts often contain shaft system holes of different sizes. Due to the limitations of tools and structures, these holes cannot be positioned and processed at one time, and can only be processed by feeding the tool at both ends of the process, that is, the two ends are processed in different processes. On the one hand, due to the irregular shape of the part, conventional soft claw clamping cannot be used; on the other hand, due to the long cantilever of the part, the clamping is unreliable when using the reverse soft claw clamping, and the tool vibration is easy to occur during processing, and even the part is easy to fall off, and the coaxiality of the hole system is difficult to ensure. However, for some parts, according to their assembly and performance requirements, the coaxiality requirements are relatively high. Deviations in coaxiality will cause assembly difficulties or performance that cannot meet the design index requirements. For this type of parts, most manufacturers currently use more complex special tooling for positioning processing or use high-precision five-axis machining centers, coordinate boring machines and other high-precision equipment for processing assurance, which has high processing costs, low production efficiency, and long R&D and processing cycles. Summary of the invention

[0003] In view of the problems existing in the background technology, the present invention aims to provide a cantilever hole processing method for special-shaped parts, which can solve the positioning and clamping problem of processing a hole at one end of the special-shaped part and then processing a hole at the other end, and can effectively ensure the coaxiality requirements of the hole system processed in two positioning and clamping steps.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for machining a cantilever hole of a special-shaped part, wherein the special-shaped part comprises a plurality of shaft system holes with different hole diameters, and the machining method comprises:

[0006] S1, select any reference surface on the special-shaped part to clamp and position the special-shaped part, and use the reference surface as a reference to machine a part of the shaft system hole on one end face of the special-shaped part, which is recorded as the machined shaft system hole;

[0007] S2, designing a positioning mandrel according to the characteristics of the machined shafting hole, the positioning mandrel comprising a positioning surface and a bulging structure, wherein the positioning surface matches with the inner wall of one hole in the machined shafting hole, and the matching clearance is less than or equal to the coaxiality requirement of the shafting hole, and the outer surface of the bulging structure matches with the inner wall of another hole in the machined shafting hole in a clearance manner;

[0008] S3, processing the positioning mandrel in S2;

[0009] S4, clamp and align the mandrel on the machine tool;

[0010] S5, install the special-shaped part in S1 into the positioning mandrel in S4 through the processed shaft system hole, position the special-shaped part through the positioning surface on the positioning mandrel, then expand the bulging structure of the positioning mandrel to complete the expansion and clamping of the special-shaped part, and process the remaining part of the shaft system hole on the other end face of the special-shaped part.

[0011] Further, in S1, the axial length of the processed shafting hole is greater than the axial length of the remaining part of the shafting hole.

[0012] Further, in S2, a hole in the processed shafting hole that is closest to the end face of the shafting hole is selected as the hole that matches the positioning surface.

[0013] Further, in S2, the expansion structure includes an expansion petal and a conical bolt, wherein the expansion petal is located at the end of the positioning core shaft, and multiple expansion petals are evenly distributed on a circumference centered on the axis of the positioning core shaft, and open grooves are provided between adjacent expansion petals. The inner surfaces of the multiple expansion petals constitute a conical surface and a threaded hole, and the conical surface is coaxial with the threaded hole, and the conical bolt includes a threaded section and a tapered head.

[0014] Furthermore, a hexagonal inner hole is arranged on the tapered head of the tapered bolt.

[0015] Furthermore, the opening groove is processed by wire cutting.

[0016] Furthermore, in S2, the positioning mandrel further includes a clamping section, and the clamping section is a stepped shaft on the positioning mandrel.

[0017] Furthermore, in S3, brass H62 is selected to process the positioning mandrel.

[0018] Furthermore, in S4, the soft jaws are first machined, and then the positioning mandrel is clamped onto the soft jaws, and the positioning surface on the positioning mandrel is aligned.

[0019] Furthermore, the cantilever hole processing method for special-shaped parts also includes S6, using three-coordinates to perform coaxiality inspection on the shaft system hole processed in S1 and the remaining part of the shaft system hole processed in S5.

[0020] The present invention is mainly used for positioning and clamping special-shaped parts in turning processing. Usually, due to the irregular shape of special-shaped parts, processing, clamping, positioning and alignment are relatively difficult. For longer holes that cannot be positioned and processed in one time, it is extremely difficult to ensure the coaxiality requirements of the hole systems at both ends. The present invention provides a solution. After the hole system at one end of the special-shaped part is processed, the inner hole is positioned and clamped when the hole system at the other end is processed to ensure the coaxiality requirements of the hole system at the other end and the processed hole system. The present invention can effectively solve the problems of inner hole processing positioning and clamping of the two-end hole systems of parts with irregular shapes that have high coaxiality requirements, and can also solve the problem of positioning and clamping of the inner hole of longer shaft parts that are processed twice to ensure coaxiality.

[0021] Compared with the prior art, the processing method of the present invention has the following characteristics:

[0022] 1. The present invention provides a reliable processing method for the axial hole system processing of special-shaped parts, which effectively ensures the coaxiality requirements of the hole systems at both ends of the special-shaped parts.

[0023] 2. The positioning mandrel used in the present invention has a short design and manufacturing cycle, which only takes 1 day to complete. It can be customized according to the shaft hole characteristics of special-shaped parts. The use of the positioning mandrel with an expansion structure to process special-shaped parts can greatly shorten the research and development and processing cycle of special-shaped parts, providing a strong technical guarantee for the development of new products.

[0024] 3. The positioning mandrel of the present invention has low manufacturing cost, and can create good economic benefits while ensuring the timely delivery of special-shaped parts with guaranteed quality and quantity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a valve housing parts drawing;

[0026] Figure 2 for Figure 1 A sectional view of the shaft system hole of the middle valve housing part;

[0027] Figure 3 It is a schematic diagram of the positioning mandrel;

[0028] Figure 4 It is a schematic diagram of a tapered bolt;

[0029] Figure 5 for Figure 1 Clamping diagram of the middle valve housing parts and the positioning mandrel. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0031] It should be noted that the special-shaped parts include a cantilever hole structure. The "cantilever" in the cantilever hole here refers to a structure with one end fixed (i.e., no axial, vertical displacement and rotation), and the other end being a free end (which can produce vertical displacement). Therefore, the "cantilever hole" refers to the hole at the free end of the cantilever structure. The cantilever hole processing method in the present invention is to remove the excess on the basis of the valve housing part casting blank to meet the design size and roughness requirements, that is, the valve housing part casting blank already has a shaft system hole (through hole), but the size of the shaft system hole does not meet the requirements. Figure 2 The technical requirements shown require removal of machining allowance.

[0032] The present invention provides a method for machining a cantilever hole of a special-shaped part, which mainly comprises the following steps:

[0033] S1: Use the rough machining reference surface to position and clamp to machine the hole system at one end of the special-shaped part. Generally, the hole system at the end with a deeper hole system is machined first as much as possible. It should be noted that the rough machining reference surface refers to any surface on the special-shaped part that has been machined and is convenient for clamping and positioning. The "rough machining" (such as milling) here is relative to the "fine machining" (such as grinding).

[0034] S2: Design a special positioning mandrel according to the structure of the processed hole;

[0035] S3: Special positioning mandrel processing;

[0036] S4: Positioning mandrel clamping and alignment;

[0037] S5: Clamp the workpiece onto the positioning mandrel and process the hole system at the other end of the part.

[0038] The positioning mandrel designed in S2 is a simple positioning and expansion device, which includes a positioning mandrel and a conical bolt.

[0039] like Figure 3As shown, the positioning mandrel designed by the present invention is usually made of H62 brass material with good elasticity. Its structure mainly includes a positioning surface and a bulging structure. The size of the positioning surface is given based on the large hole on the end face of the special-shaped part to ensure that the clearance between the positioning surface and the large hole is not greater than the coaxiality requirement; the working surface (bulging surface) of the bulging structure is given according to the size of the expanded inner hole to ensure a certain clearance; the bulging structure also includes a bulging cone surface and a guide threaded hole. The taper of the bulging cone surface is usually designed to be less than or equal to 30°. The guide threaded hole needs to be adjusted according to the level of matching accuracy. For special-shaped parts with higher precision, fine pitch threads can be used for matching to improve the tightness of matching. After the working surface of the bulging structure is processed, the bulging working surface is cut along the axial direction through the center by wire cutting to cut multiple evenly distributed open grooves with a width of 2mm to 3mm. One end of the positioning mandrel also includes a clamping section, which is a step shaft on the positioning mandrel.

[0040] like Figure 4 As shown in the figure, the conical bolt designed by the present invention needs to be made of high-strength steel. The material needs to be heat-treated to improve hardness and wear resistance. The hardness needs to be controlled above HRC42. The conical bolt is machined with threads matching the guide threaded holes on the positioning mandrel and an outer cone surface with the same taper as the bulging cone surface on the positioning mandrel. To avoid interference, the head of the conical bolt can adopt a cylindrical head internal hexagonal structure. Of course, if there is no structural restriction, it can also be made into an external hexagonal structure. The conical bolt can be modified with the corresponding standard bolt.

[0041] The working principle of the positioning mandrel is as follows: the conical bolt is screwed into the guide threaded hole at the end of the positioning mandrel. As the conical bolt is screwed in, the outer conical surface of the conical bolt fits with the conical surface (inner conical surface) of the bulging structure. The conical bolt continues to be screwed in, and the working surface of the bulging structure expands, and the outer circle increases, forming a tight fit with the inner hole wall of the shaft system hole of the special-shaped part to be processed, and the inner hole is expanded, thereby clamping the special-shaped part.

[0042] The steps for using the positioning mandrel to clamp and process special-shaped parts are as follows:

[0043] S1. Install the clamping section of the positioning mandrel onto the three-jaw chuck of the lathe, and use a dial indicator or micrometer to align the positioning surface to ensure that its radial runout is no more than half of the required tolerance of the form and position.

[0044] S2. Install the special-shaped part to be processed onto the positioning mandrel, and tighten the conical bolt to tighten the special-shaped part.

[0045] S3. Process the elements to be processed of the special-shaped parts, ensure the relevant dimensions of the special-shaped parts, and then use a dial indicator or micrometer to check the runout of the processed shaft hole. After the special-shaped parts are processed, the three-coordinate measurement is used to measure the hole system at both ends, and the coaxiality of the hole system at both ends is checked.

[0046] The following Figure 1 The valve housing shown in the figure is used as a processing object to specifically introduce the cantilever hole processing method of the special-shaped parts of the present invention. Figure 2 As shown, Figure 1 The shaft system holes to be processed in the middle valve housing include ΦB, ΦC, ΦD, ΦE, ΦF, ΦG, ΦH and ΦI.

[0047] S1, use the bottom surface of the blank mounting seat of the valve housing as the rough reference for positioning and clamping the valve housing. Figure 2 The left end hole system shown includes ΦB, ΦC, ΦD, ΦE, ΦF, etc.;

[0048] S2, take the inner wall of ΦB as the positioning surface and ΦD as the tightening working surface, and design and process as follows Figure 2 , 3 and the positioning mandrel shown in 5, and Figure 4 Conical bolts;

[0049] S3, turn the soft jaws, install the clamping section of the positioning mandrel on the soft jaws, and align the outer circle of the positioning reference surface ΦB' on the positioning mandrel (matching with the ΦB hole), and use a micrometer to check that the outer circle runout should not be greater than 0.01mm;

[0050] S4, press the valve housing parts with the left end hole system processed Figure 5 Install it on the positioning mandrel as shown, tighten the conical bolt, expand the working surface and expand the ΦD inner hole of the valve housing;

[0051] S5, machining the right end hole system of the valve housing;

[0052] S6, check all processing elements of the parts and use a three-coordinate measuring machine to Figure 2 The coaxiality shown requires checking.

[0053] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for machining cantilever holes of special-shaped parts, wherein the special-shaped parts include a plurality of shaft system holes with different hole sizes, characterized in that: Processing methods include: S1, select any reference surface on the special-shaped part to clamp and position the special-shaped part, and use the reference surface as a reference to machine a part of the shaft system hole on one end face of the special-shaped part, which is recorded as the machined shaft system hole; S2, designing a positioning mandrel according to the characteristics of the machined shafting hole, the positioning mandrel comprising a positioning surface and a bulging structure, wherein the positioning surface matches with the inner wall of one hole in the machined shafting hole, and the matching clearance is less than or equal to the coaxiality requirement of the shafting hole, and the outer surface of the bulging structure matches with the inner wall of another hole in the machined shafting hole in a clearance manner; S3, processing the positioning mandrel in S2; S4, clamp and align the mandrel on the machine tool; S5, install the special-shaped part in S1 into the positioning mandrel in S4 through the processed shaft system hole, position the special-shaped part through the positioning surface on the positioning mandrel, then expand the bulging structure of the positioning mandrel to complete the expansion and clamping of the special-shaped part, and process the remaining part of the shaft system hole on the other end face of the special-shaped part.

2. A method for machining cantilever holes of special-shaped parts according to claim 1, characterized in that: In the above-mentioned S1, the axial length of the processed shafting hole is greater than the axial length of the remaining part of the shafting hole.

3. The method for machining cantilever holes of special-shaped parts according to claim 1, characterized in that: In S2, a hole in the processed shafting hole that is closest to the end face of the shafting hole is selected as the hole that matches the positioning surface.

4. The method for machining cantilever holes of special-shaped parts according to claim 1, characterized in that: In S2, the expansion structure includes an expansion petal and a conical bolt, wherein the expansion petal is located at the end of the positioning core shaft, and multiple expansion petals are evenly distributed on a circumference centered on the axis of the positioning core shaft, and open grooves are formed between adjacent expansion petals. The inner surfaces of the multiple expansion petals constitute a conical surface and a threaded hole, and the conical surface is coaxial with the threaded hole, and the conical bolt includes a threaded section and a tapered head.

5. A method for machining cantilever holes of special-shaped parts according to claim 4, characterized in that: A hexagonal inner hole is arranged on the tapered head of the tapered bolt.

6. A method for machining cantilever holes of special-shaped parts according to claim 4, characterized in that: The opening groove is processed by wire cutting.

7. The method for machining cantilever holes of special-shaped parts according to claim 1, characterized in that: In S2, the positioning mandrel further includes a clamping section, and the clamping section is a stepped shaft on the positioning mandrel.

8. The method for machining cantilever holes of special-shaped parts according to claim 1, characterized in that: In S3, brass H62 is selected to process the positioning mandrel.

9. The method for machining cantilever holes of special-shaped parts according to claim 1, characterized in that: In the above S4, the soft jaws are first machined, and then the positioning mandrel is clamped onto the soft jaws, and the positioning surface on the positioning mandrel is aligned.

10. The method for machining cantilever holes of special-shaped parts according to claim 1, characterized in that: It also includes S6, which uses three-coordinate measurement to check the coaxiality of the shaft system hole processed in S1 and the remaining part of the shaft system hole processed in S5.

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