Combined machining method for special-shaped arc structural part and auxiliary clamp tool

Abstract

The invention relates to a combined machining method for a special-shaped arc structural part and an auxiliary clamp tool. The combined machining method comprises the following steps that blanking is conducted; milling is conducted; milling and forming; carrying out linear cutting; boring is conducted; on the horizontal boring and milling center, fine boring of the hole and machining of a step surface are completed through the auxiliary clamp; tapping is conducted; and quality detection. The clamp tool is matched with a horizontal boring and milling center for machining according to the boring procedure of a stainless steel special-shaped part, and comprises a two-piece clamp body and a pressing plate I; the other end of the clamp body is characterized in that two sides of the clamp body are internally arc-shaped, and the clamp body is tightly attached to the outer contour of the special-shaped part to form a V-shaped iron positioning structure. According to the machining method and the auxiliary clamp tool, efficient and precise machining of the special-shaped part is achieved through collaborative optimization of a staged combination process and a special clamp. The precision is improved while clamping innovation is achieved, and the clamp has the advantages of being high in precision, low in cost and large in batch and is suitable for the high-requirement field such as aerospace.

Description

Technical Field

[0001] The present invention relates to the technical field of machining, and in particular to a combined machining method and an auxiliary fixture tooling for special-shaped arc structural parts. Background Art

[0002] In the field of machining, especially for complex support parts required in aerospace and precision instruments, the machining technology of special-shaped arc structural parts faces significant challenges due to their irregular contours, high-precision geometric tolerances, and strict roughness requirements. Such parts are usually made of difficult-to-machine materials such as 316L stainless steel, and their high strength, high toughness, and easy heat deformation characteristics further increase the machining difficulty. In traditional machining methods, due to the irregular shape and large height of the parts, multiple positioning or split fixtures are required during clamping, resulting in insufficient clamping rigidity, easy vibration during machining, and affecting dimensional accuracy (such as out-of-roundness and parallelism deviation) and surface quality.

[0003] In addition, multi-process step-by-step machining (such as milling, wire cutting, boring, etc.) requires frequent tooling changes, and cumulative errors are likely to occur in the process connection. The scrap rate is as high as more than 15%, and the production cycle is long, making it difficult to meet batch requirements. Although there are attempts to use V-blocks or combined fixtures in the prior art, their adaptability is poor and the adjustment is cumbersome, and they cannot balance high precision and high efficiency. Therefore, there is an urgent need for a technical solution integrating efficient machining processes and special auxiliary devices to solve the core problems of poor clamping stability, difficult precision control, and low process coordination efficiency, and to achieve batch high-quality production of complex special-shaped parts. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a combined machining method for special-shaped arc structural parts. The combined machining method is designed for batch production of special-shaped parts with complex shapes, high precision requirements, and difficult clamping of stainless steel, and includes the following steps:

[0005] Step S1: Blanking; Use a band saw to prepare the material, and add a process stub on one side of the blank lengthwise.

[0006] Step S2: Milling; Rough and finish plane the hexahedron, and machine notches on both sides for subsequent fixing by clamp plate I.

[0007] Step S3: Milling forming; Use a vertical machining center to mill the upper and lower half profiles and step surfaces in two clamps.

[0008] Step S4: Wire cutting; Cut the process stub and the internal hole structure.

[0009] Step S5: Boring; On a horizontal boring and milling center, use an auxiliary fixture to complete the fine boring of the holes and the machining of the step surfaces.

[0010] Step S6: Tapping; threading and completing surface treatment, deburring and chamfering.

[0011] In an embodiment of the present invention, in the milling forming process, a vertical machining center uses cemented carbide cutting tools, with a cutting speed of 80 - 120 m / min and a feed rate of 0.1 - 0.2 mm / r.

[0012] In an embodiment of the present invention, in the wire cutting process, a brass electrode wire with a diameter of 0.25 mm is used, and the machining current is 4 - 6 A.

[0013] In an embodiment of the present invention, in the boring process, the spindle speed is 800 - 1000 rpm, and a water-based emulsion is used as the coolant.

[0014] In an embodiment of the present invention, after deburring, the final product part is sent for quality inspection, where a coordinate measuring machine is used to verify the coaxiality of the process hole and the reference.

[0015] The present invention also provides a professional auxiliary fixture tooling based on a special-shaped arc structural part. The fixture tooling is used for machining a special-shaped stainless steel part in the boring process in cooperation with a horizontal boring and milling center, and includes a two-piece fixture body and a pressing plate Ⅰ. One end of the fixture body has a planar feature, and after the planar feature contacts the working plane on the boring and milling center, the planar feature is ground with a flatness ≤ 0.01 mm. At the same time, after the part is assembled and machined on the fixture body, the pressing plate Ⅰ is arranged to squeeze and fix at the notch on the outer side of the part. The other end of the fixture body has two inner arc features on both sides, which closely fit the outer contour of the special-shaped part, with a fitting gap ≤ 0.05 mm. There are two inner arc features, forming a V-shaped iron positioning structure.

[0016] In an embodiment of the present invention, the curvature radius of the inner arc of the fixture body matches the outer contour of the special-shaped part, with a tolerance of ±0.01 mm.

[0017] In an embodiment of the present invention, the side of the fixture body is provided with a quick installation slot, and there is a pressing plate Ⅱ between the interface on the working plane of the boring and milling center. There are four pressing plates Ⅱ in left-right symmetry, and the installation repeat positioning accuracy ≤ 0.01 mm.

[0018] In an embodiment of the present invention, the body of the fixture body is made of 42CrMo alloy steel, quenched and tempered to a hardness of HRC45 - 50, and surface-hard chromium plated.

[0019] The above technical solution of the present invention has the following advantages compared with the prior art: The processing method and the auxiliary fixture tooling of the present invention realize the efficient and precise processing of special-shaped parts through the collaborative optimization of the staged combination process and the special fixture. Precision improvement: The qualified rate of geometric tolerances has increased from 70% to 98%, the roundness is ≤0.006 mm, and the surface roughness Ra is ≤1.6 μm; Clamping innovation: The fitting gap of the two-piece fixture is ≤0.05 mm, the amplitude is ≤0.02 mm, and it is suitable for multiple parts; Efficiency optimization: The collaborative process has shortened the production cycle by 30%, and the scrap rate has decreased from 15% to 3%; It has the advantages of high precision, low cost and batch production, and is suitable for high-demand fields such as aerospace. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below according to the specific embodiments of the present invention in conjunction with the drawings.

[0021] Figure 1 is the assembly structure schematic diagram of the professional auxiliary fixture tooling based on the special-shaped arc structure part of the present invention;

[0022] Figure 2 is the schematic diagram of the special-shaped part of the present invention;

[0023] Figure 3 is the sectional schematic diagram of the special-shaped part of the present invention;

[0024] Figure 4 is the structure diagram of the fixture body of the present invention.

[0025] Figure 5 is the schematic diagram of the geometric requirements of the milling process of the present invention.

[0026] As shown in the figure, 1. Special-shaped part; 2. Fixture body; 3. Press plate I; 4. Press plate II; 5. Working plane. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Example 1

[0028] This embodiment provides a combined processing method for a special-shaped arc structure part. The combined processing method is designed for the batch production of special-shaped parts 1 made of stainless steel with complex shapes, high precision requirements and difficult clamping as shown in Figure 2 , 3 and includes the following steps:

[0029] Step S1: Blanking; Use a band sawing machine to prepare materials. The material is a 316L stainless steel blank with a size of Φ300×472 mm, and a process stub is added by 20 mm on one side in the length direction.

[0030] Step S2: Milling; Rough and finish planing the hexahedron to 172 mm × 290 mm × 470 mm, with the parallelism / perpendicularity controlled within ±0.2 mm; Processing the 40 mm × 10 mm notches on both sides on a gantry planer-miller for fixing the pressing plate Ⅰ of the subsequent vertical machining center;

[0031] Step S3: Milling and forming; Milling the upper and lower half profiles and step surfaces in two setups through a vertical machining center, controlling the dimensions of 138 ± 0.1 mm, 282 ± 0.15 mm, Φ108 ± 0.11 mm and the 4 × R15 arcs;

[0032] Step S4: Wire cutting; Cutting the process lugs on both sides in the total length direction to ensure the total length of 432 ± 0.2 mm; Cutting the 35 × 60 × R5 rectangular hole and the Φ57 and Φ66 holes, with the hole pitch dimension controlled at 150 ± 0.125 mm;

[0033] Step S5: Boring; On a horizontal boring and milling center, and completing the following steps using an auxiliary fixture:

[0034] Boring the Φ72 holes at the left and right ends to a depth of 365 mm and 385 mm, with the hole depth matching the total part dimension;

[0035] Finish boring the Φ60, Φ69, Φ95, Φ96 holes, with the roundness controlled ≤ 0.006 mm and the surface roughness Ra ≤ 1.6 μm;

[0036] Step S6: Thread tapping; Tapping the 6 × M10 - 7H, 4 × M5 - 7H and M14 - 7H threads, deburring and chamfering.

[0037] The specific process flow is as shown in Table 1 below:

[0038]

[0039] Specifically, after obtaining the final product, quality inspection is carried out, where the surface roughness of the inner hole is measured by a surface roughness measuring instrument, the roundness of the inner hole is measured by a roundness measuring instrument, and the coaxiality of each hole is verified by a coordinate measuring machine. After passing the inspection, it is transferred to the next process.

[0040] The items to note in the inspection are as shown in the following table:

[0041]

[0042]

[0043] Example 2

[0044] In addition, as Figure 1 and Figure 2As shown in the figure, this embodiment provides a professional auxiliary fixture tooling based on a special-shaped arc structural part. The fixture tooling is used for the boring process of a special-shaped part 1 made of stainless steel and cooperates with a horizontal boring and milling center for machining. It includes a two-piece fixture body 2 and a pressing plate I 3. One end of the fixture body 2 has a planar feature. After the planar feature contacts the working plane 5 on the boring and milling center, the planar feature is ground, and the flatness is ≤ 0.01 mm. At the same time, after the part is assembled and machined on the fixture body 2, the pressing plate I 3 is arranged at the notch on the outer side of the part and is fixed by extrusion. The other end of the fixture body 2 has inner arc features on both sides, which closely fit the outer contour of the special-shaped part 1, and the fitting gap is ≤ 0.05 mm. There are two inner arc features, that is, a V-shaped iron positioning structure is formed.

[0045] As Figure 2 , Figure 4 shown, the curvature radius of the inner arc of the fixture body 2 matches the outer contour of the special-shaped part, and the tolerance is ±0.01 mm.

[0046] Furthermore, as Figure 1 and Figure 4 shown, the side of the fixture body 2 is provided with a quick installation card slot, and there is a pressing plate II 4 between the upper interface of the working plane of the boring and milling center. It is axisymmetric left and right, and there are four pressing plates II 4 in total, and the installation repeat positioning accuracy is ≤ 0.01 mm.

[0047] At the same time, the body of the fixture body 2 is made of 42CrMo alloy steel, quenched and tempered to a hardness of HRC45 - 50, and the surface is treated with hard chromium plating.

[0048] In the clamping stage of the professional auxiliary fixture tooling described in this embodiment 2: Place the part on the auxiliary device, use the inner arc to fit the outer shape, and press and fasten with the pressing plate. And the planar feature is ground to ensure that the flatness is ≤ 0.01 mm, and the inner arcs on both sides of the upper end closely fit the outer shape of the part, and the fitting gap is ≤ 0.05 mm.

[0049] The specific principle is to adopt the V-shaped iron positioning principle, fix the part through the pressing plate, and ensure that the part does not displace or vibrate during machining. It is used in step S5 to cooperate with the boring and milling center to improve the stability during boring.

[0050] Therefore, the combined machining method in Embodiment 1 is through staged combined machining and special fixtures, and the qualified rate of the form and position tolerance accuracy of the part is increased from 70% to 98%; at the same time, the process connection is tight, the batch production cycle is shortened by 30%, and the scrap rate is reduced from 15% to 3%, significantly saving materials and rework costs.

[0051] In summary, the combined processing method of the present invention's solution meets the requirements of mass production of complex parts in the fields of aerospace, precision instruments, etc. at the present stage. By controlling the processing accuracy in stages through combined processes and using special fixtures to improve the clamping rigidity, the problems of high rejection rate and low efficiency in the processing of special-shaped parts are solved.

[0052] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A combined machining method for special-shaped arc structural parts, the combined machining method is designed for batch production of special-shaped parts made of stainless steel with complex shapes, high precision requirements and difficult clamping, and is characterized in that, It includes the following steps: Step S1: Blanking; Prepare materials using a band saw, and extend the blank unilaterally in the length direction to form a process stub. Step S2: Milling; Rough and finish planing the hexahedron, and machining notches on both sides for subsequent fixing of pressing plate I. Step S3: Milling and forming; Milling the outer shape and step surfaces of the upper and lower halves in two setups through a vertical machining center. Step S4: Wire cutting; Cutting the process stub and the internal hole structure. Step S5: Boring; On a horizontal boring and milling center, and using an auxiliary fixture to complete the fine boring of the hole and the machining of the step surface. Step S6: Thread tapping; Tapping the thread and completing the surface treatment to remove burrs and chamfer the edges.

2. The combined processing method according to claim 1, wherein: In the process of milling and forming, the vertical machining center uses carbide cutting tools, the cutting speed is 80 - 120 m / min, and the feed rate is 0.1 - 0.2 mm / r.

3. The combined processing method according to claim 1, characterized in that: In the process of wire cutting, a brass electrode wire with a diameter of 0.25 mm is used, and the machining current is 4 - 6 A.

4. The combined processing method according to claim 1, characterized in that: In the process of boring, the spindle speed is 800 - 1000 rpm, and water-based emulsion is used as the coolant.

5. The combined processing method according to claim 1, wherein: After deburring, the final product parts are sent for quality inspection, and a coordinate measuring machine is used to verify the coaxiality of the process hole and the datum.

6. A professional auxiliary fixture tooling based on a special-shaped arc structural member, the fixture tooling is for the boring process of the special-shaped parts made of stainless steel in Claim 1, and is used for machining in cooperation with a horizontal boring and milling center, and is characterized in that: It includes a two-piece fixture body and pressing plate I; One end of the fixture body has a planar feature, and after the planar feature contacts the working plane on the boring and milling center, the planar feature is ground. At the same time, after the machining part is assembled on the fixture body, the pressing plate I is arranged to squeeze and fix at the notch on the outer side of the part; The other end of the fixture body has inner arc features on both sides, which are closely fitted with the outer contour of the special-shaped part; Therefore, there are two inner arc features, forming a V-shaped iron positioning structure.

7. The professional auxiliary fixture tooling according to claim 6, characterized in that: The curvature radius of the inner arc of the fixture body matches the outer contour of the special-shaped part, and the tolerance is ±0.01 mm.

8. The professional auxiliary fixture tooling according to claim 6, characterized in that: The side of the fixture body is provided with a quick installation slot, and there is a pressing plate II between the interface on the working plane of the boring and milling center. It is axisymmetric left and right, and there are four pressing plates II in total, and the installation repeat positioning accuracy ≤0.01 mm.

9. The professional auxiliary fixture tooling according to claim 6, characterized in that: The body of the fixture body is made of 42CrMo alloy steel, quenched and tempered to a hardness of HRC45 - 50, and surface-hard chromium-plated.

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