Method for machining a 3.8 m integral tank bottom with surface features

Abstract

The application provides a processing method of a 3.8m integral box bottom with surface features, which comprises the following steps: processing an inner shape surface of a product blank, sleeving the processed inner shape of the product blank on an outer shape surface of a tooling, clamping the tooling, processing an outer shape surface of the product to remove an excess wall thickness of the outer shape, dividing a large curved surface of a processing area into a plurality of small curved surfaces, and using a T-shaped outer spherical surface pressing mechanism in a fine milling process of the product blank. The application has the beneficial effects that: the processing method design of the product is reasonable in combination with the structure and size precision characteristics of the product; the processing quality of the wall thickness of the box bottom is further controlled by designing a fine milling tooling and reasonably dividing the processing shape surface and the fine milling processing sequence.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of machining of weak-rigidity parts, and particularly relates to a machining method of a 3.8m integral box bottom with surface feature structures. BACKGROUND

[0002] The inner shape of the part is ellipsoidal, the large end has a diameter of 3800mm, the height is about 1200mm, the maximum thickness is 15mm, the thin area of the part has a thickness of 3mm, the spherical surface has multiple flange holes and flanges and flange welding bosses, and the part is a typical weak-rigidity thin-walled product. Figure 1 As shown in the figure.

[0003] The part is used for welding connection with multiple components, and the shape and position tolerances and wall thicknesses of the intermediate positions have high technical requirements. The part has the following machining difficulties: 1) the integral bottom is formed by spinning, and the blank has a small excess amount. The spinning precision of the blank directly affects the machining quality, 2) the box bottom is formed by spinning, and the inner stress is large, and the surface deviation is large. In order to ensure the machining stability in machining, the clamping difficulty is large. 3) In order to ensure the welding quality of the rear box bottom and the weight reduction requirement, the wall thickness of the box bottom is extremely high.

[0004] Due to the large diameter of the product, the structure is extremely poor in rigidity, and the size requirement is high. The machining of the curved surface wall thickness is a machining difficulty of the product. The large machining area of the large-diameter box bottom has a large surface fitting difficulty, and the shape surface has few clamping positions. After the local surface of the product is deformed in machining, it is difficult to ensure the wall thickness of the product by turning. Milling also faces the problem of unstable wall thickness caused by surface deformation. INVENTION CONTENTS

[0005] Therefore, the application aims to provide a machining method of a 3.8m integral box bottom with surface feature structures, so as to solve at least one technical problem in the background art.

[0006] To achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0007] The machining method of the 3.8m integral box bottom with surface feature structures comprises the following steps: machining the inner shape surface of the product blank, then sleeving the machined inner shape of the product blank on the outer shape surface of the tooling, clamping the product blank by using the clamping tooling, machining and removing the excess wall thickness of the outer shape surface of the product after clamping, dividing the large curved surface of the machining area into a plurality of small curved surfaces, and using a T-shaped outer spherical surface pressing mechanism during the finish milling of the product blank.

[0008] Further, the product blank has a length of 150mm or more at the large end, the product has a length of 15mm or more at the outer shape and the inner shape, and the product blank is provided with a plurality of circumferentially distributed corner pieces for clamping at the outer circle of the 150mm area of the large end.

[0009] Further, the small curved surface units are segmented according to the plane deviation of 2-2.5 mm after segmentation.

[0010] Further, the clamping tool includes a base, a clamping structure;

[0011] The clamping structure is arranged around the periphery of the base.

[0012] The clamping structure includes an outer circle clamping assembly, an adjusting support assembly, and a workbench, and the outer circle clamping assembly and the adjusting support assembly are arranged on the workbench along the periphery.

[0013] One end of the workbench is arranged on the base.

[0014] Further, the base is in a semi-spherical shape, and a first circular table corresponding to the product blank and a second circular table for mounting the clamping structure are arranged at the bottom of the base.

[0015] The outer diameter of the first circular table of the base corresponds to the inner diameter of the product blank.

[0016] Further, a I-shaped groove is arranged on the workbench, and the outer circle clamping assembly and the adjusting support assembly are arranged at the I-shaped groove, and the position of the outer circle clamping assembly corresponds to the position of the corner piece.

[0017] The outer circle clamping assembly includes a clamping table, a clamping jack, a clamping guide rod, and a clamping plate.

[0018] The bottom of the clamping table is arranged at the I-shaped groove, the mounting end of the clamping jack is arranged at the end of the clamping table, the clamping plate is arranged at the output end of the clamping jack, and the clamping plate is provided with a through hole through which the clamping guide rod passes.

[0019] The clamping guide rod is arranged on the clamping table and between the clamping table and the adjusting support assembly.

[0020] The upper end of the clamping guide rod is provided with a clamping nut.

[0021] Further, the adjusting support assembly includes an adjusting table and an adjusting jack.

[0022] The bottom of the adjusting table is mounted at the I-shaped groove, and the mounting end of the adjusting jack is arranged at the end of the adjusting table.

[0023] The output end of the mounting end of the adjusting jack corresponds to the periphery of the first circular table.

[0024] Further, the T-shaped outer spherical surface pressing mechanism includes a plurality of T-shaped keels, and the plurality of T-shaped keels are arranged on the product blank through first bolts.

[0025] The end of the T-shaped outer spherical surface pressing assembly is arranged on the base through second bolts.

[0026] Further, the number of T-shaped outer spherical surface compression assemblies is 2.

[0027] Further, the second bolt is a double-row bolt; a plurality of double-row bolts are respectively arranged on the T-shaped keel, and the double-row bolts are arranged along the spherical surface of the base.

[0028] Compared with the prior art, the processing method of the 3.8 m integral box bottom with a surface feature structure has the following advantages:

[0029] 1) The whole set of tooling is designed: since the large-diameter spinning bottom is prone to deformation in the finishing stage, a reasonable clamping tooling is designed to ensure the stability of the clamping state of the part during the machining process, to enhance the overall rigidity of the part, and to maximize the limitation of the deformation of the part, and to ensure the machining accuracy.

[0030] 2) The processing method of reasonable partition of large curved surface: the spherical surface machining area is large, and the single program is large area machining, and there are problems of long machining cycle and easy deformation of the part, therefore, according to the part curved surface data, the curved surface is divided according to the reasonable clamping machinable area, so that the curvature change of the single curved surface after division is small, and the wall thickness change in the machining process is small.

[0031] According to the product structure and size precision characteristics, the product processing process is reasonably designed, the precision milling processing tooling is designed, and the processing surface is reasonably divided and the precision milling processing sequence is further controlled to control the processing quality of the box bottom wall thickness. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the present application and its description are used to explain the present application and are not used to limit the present application. In the drawings:

[0033] Figure 1 The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the present application and its description are used to explain the present application and are not used to limit the present application. In the drawings:

[0034] Figure 2 The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the present application and its description are used to explain the present application and are not used to limit the present application. In the drawings:

[0035] Figure 3 The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the present application and its description are used to explain the present application and are not used to limit the present application. In the drawings:

[0036] Figure 4 The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the present application and its description are used to explain the present application and are not used to limit the present application. In the drawings:

[0037] Explanation of the drawings:

[0038] 1, base; 2, workbench; 3, first circular table; 4, second circular table; 5, I-shaped groove; 6, clamping table; 7, clamping jack; 8, clamping guide rod; 9, clamping plate; 10, clamping nut; 11, adjusting table; 12, adjusting jack; 13, T-shaped keel; 14, first bolt; 15, second bolt; 16, angle piece. DETAILED DESCRIPTION

[0039] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0040] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0041] A processing method of a 3.8m integral box bottom with surface features, comprising the following steps: processing the inner shape surface of the product blank, then sleeving the already processed inner shape of the product blank on the outer shape surface of the tooling, and using the clamping tooling to hold, after clamping, processing the outer shape surface of the product in zones to remove the excess wall thickness of the outer shape, dividing the large curved surface of the processing area into several small curved surfaces, and using a T-shaped outer spherical surface pressing mechanism during the fine milling process of the product blank. There is a 150mm or more excess amount left at the large end of the product blank, and there is a 15mm or more excess amount on the product outer shape and inner shape. The outer circle of the product blank in the 150mm area of the large end is provided with circumferentially distributed angle pieces 16 for clamping. The small curved surface units are segmented according to a planar deviation of 2-2.5mm.

[0042] The clamping tooling comprises a base 1 and a clamping structure; a plurality of clamping structures are arranged along the circumference of the four sides of the base 1; the clamping structure comprises an outer circle clamping assembly, an adjusting support assembly, and a workbench 2, the outer circle clamping assembly and the adjusting support assembly are arranged on the workbench 2 along the circumference; one end of the workbench 2 is arranged on the base 1.

[0043] The base 1 is semispherical, and the bottom is provided with a first circular table 3 corresponding to the blank product and a second circular table 4 for mounting the clamping structure. The outer diameter of the first circular table 3 of the base 1 corresponds to the inner diameter of the product blank.

[0044] The workbench 2 is provided with an I-shaped groove 5, and the outer circle clamping assembly and the adjusting support assembly are arranged at the I-shaped groove 5, and the position of the outer circle clamping assembly corresponds to the position of the angle piece 16; the outer circle clamping assembly comprises a clamping table 6, a clamping jack 7, a clamping guide rod 8, and a clamping plate 9; the bottom of the clamping table 6 is arranged at the I-shaped groove 5, the mounting end of the clamping jack 7 is arranged at the end of the clamping table 6, the clamping plate 9 is arranged at the output end of the clamping jack 7, and the clamping plate 9 is provided with a through hole through which the clamping guide rod 8 can pass; the clamping guide rod 8 is arranged on the clamping table 6 and between the clamping table 6 and the adjusting support assembly; the upper end of the clamping guide rod 8 is provided with a clamping nut 10.

[0045] The adjusting support assembly comprises an adjusting platform 11 and an adjusting jack 12; the bottom of the adjusting platform 11 is mounted at the I-shaped groove 5, and the mounting end of the adjusting jack 12 is arranged at the end of the adjusting platform 11; and the output end of the mounting end of the adjusting jack 12 corresponds to the periphery of the first circular platform 3.

[0046] The T-shaped outer spherical surface pressing mechanism comprises a plurality of T-shaped keels 13 arranged on the product blank through first bolts 14; and the end of the T-shaped outer spherical surface pressing assembly is arranged on the base 1 through second bolts 15.

[0047] The number of the T-shaped outer spherical surface pressing assembly is 2; the second bolts 15 are double-row bolts; and a plurality of sets of double-row bolts are respectively arranged on the T-shaped keels 13 and arranged along the spherical surface of the base 1.

[0048] Since the thin-walled box bottom is prone to deformation in the finishing stage, a reasonable clamping tool needs to be designed to enhance the overall rigidity of the part during the entire machining process, to maximize the limitation of the deformation of the part, to ensure the machining precision, and to effectively control the deformation of the part and reduce the wall thickness deviation during the finish milling stage. The curved surface is reasonably divided into a plurality of small milling units, the single area milling cycle is short, the deformation is small, and the wall thickness tolerance is more easily ensured. At the same time, the milling sequence of the small milling units is reasonably planned, and the influence of the product deformation on the wall thickness machining is further reduced.

[0049] Since the large-diameter thin-walled box bottom is prone to deformation in the finishing stage, a reasonable clamping tool needs to be designed to enhance the overall rigidity of the part during the entire machining process, to maximize the limitation of the deformation of the part, and to ensure the machining precision.

[0050] The product is a sheet metal forming blank, and the outer shape and the inner shape both have a surplus of more than 15 mm; the product blank has a surplus of more than 150 mm at the large end. In order to facilitate the clamping of the subsequent parts, 16 angle pieces 16 are welded on the outer circle of the 150 mm area of the large end for clamping. The process flow is to first machine the inner surface of the product, i.e. to first machine the inner spherical surface of the hemispherical product, to ensure that the inner surface matches the outer spherical surface of the jig. After the inner surface is machined, the product is sleeved on the outer surface of the tooling, so that the inner surface of the product tightly fits the outer surface of the jig. After clamping, the outer surface of the product is machined in zones to remove the excess wall thickness surplus of the outer shape.

[0051] The box bottom is processed by first processing the inner profile surface and then processing the outer profile surface. The wall thickness of the spherical surface is ensured during the processing of the outer profile surface. Therefore, the whole inner support fixture is adopted to support the inner profile surface. Since the inner profile surface has a large bonding area, the part will have a certain roundness deformation after processing. The part and the fixture are assembled by using a clearance fit to ensure the bonding of the inner surface of the part and the fixture. The outer circle 16 of the tool is pressed by the outer circle pressing mechanism to ensure the bonding of the part and the fixture. The lower end surface is uniformly provided with a lower end surface support mechanism which can freely adjust the height, providing an end surface reference for product assembly. At the same time, the large end surface of the part has 16 adjustable support mechanisms which can be adjusted in height before the part is pressed to ensure that the large end surface of the part is horizontal after the part is pressed. At the same time, it can be used as a top opening mechanism when the part is disassembled.

[0052] The profile of the product is gradually thinned during the fine milling process, but only the large end plate of the outer profile surface is fixed on the spherical surface without more support. During the processing, the spherical surface is easy to deform slowly, which affects the processing quality. Therefore, a T-shaped outer spherical surface pressing mechanism is designed outside the tool. The device is composed of a T-shaped profile body. The front and rear ends are connected to the workbench 2 and the top surface of the fixture by bolts, respectively. A plurality of double-row screws are installed on the T-shaped keel 13. The screws move along the normal direction of the spherical surface to press the part tightly, so that the part and the fixture are further bonded and not loose. Two sets of T-shaped outer spherical surface pressing mechanisms can form a relatively stable spherical surface processing area, reducing the deformation of the part during the outer shape processing.

[0053] To further control the wall thickness tolerance, the large curved surface of the processing area is divided into several small curved surfaces. In order to consider the processing efficiency (the curved surface should not be too small), and according to the characteristics of the inconsistent ellipsoidal spherical curved surface, the small curved surface unit plane deviation is 2-2.5mm after segmentation. According to the product processing area (in the region of spherical diameter Φ680-Φ3736).

[0054] Table 1: Axial and circumferential segmentation size of ellipsoidal surface

[0055] Serial number Maximum split arc length in the axial direction Maximum split arc length in the axial direction Remarks 1 125 180 Diameter Φ3736 at the start of the large end 2 125 180 3 140 180 4 150 175 5 160 170 6 175 165 7 190 155 8 200 145 9 215 130 10 225 120 11 225 100 Diameter Φ680 at the start of the small end

[0056] The existing processing method is without external T-shaped outer spherical surface pressing mechanism. The product is segmented according to the axial direction, and the axial segmentation arc length is 300-400mm. According to this method, the maximum and minimum deviation of the wall thickness is about 3-5mm. According to the scheme of the present application, the maximum and minimum deviation of the wall thickness can be reduced to 1.5mm.

[0057] The above description is only a preferred embodiment of the present application and does not limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of machining a 3.8 m integral tank bottom with surface features, characterized by: It comprises the following steps: processing the inner shape of the product blank, then sleeving the processed inner shape of the product blank on the outer shape of the tooling, clamping using the clamping tooling, after clamping, removing the excess wall thickness of the outer shape by processing the outer shape of the product in sections, dividing the large curved surface of the processing area into several small curved surfaces, using a T-shaped outer spherical surface pressing mechanism during the fine milling process of the product blank; The product blank has a 150mm or more excess at the large end, and the product has a 15mm or more excess in the outer shape and the inner shape, and the product blank has a circumferentially distributed corner piece for clamping on the outer circle of the 150mm area at the large end; The small curved surface unit is divided according to a planar deviation of 2-2.5mm; The clamping tooling comprises a base and a clamping structure; The clamping structure is arranged around the periphery of the base; The clamping structure comprises an outer circle clamping assembly, an adjusting support assembly, and a workbench, and the outer circle clamping assembly and the adjusting support assembly are arranged on the workbench along the circumference; One end of the workbench is arranged on the base; The base is semispherical, and the bottom is provided with a first circular table corresponding to the product blank and a second circular table for mounting the clamping structure; The outer diameter of the first circular table of the base corresponds to the inner diameter of the product blank; The T-shaped outer spherical surface pressing mechanism comprises a plurality of T-shaped keels, and the plurality of T-shaped keels are arranged on the product blank through first bolts; The end of the T-shaped outer spherical surface pressing assembly is arranged on the base through second bolts; The second bolts are double-row bolts; a plurality of sets of double-row screws are mounted on the T-shaped keels and arranged along the spherical surface of the base.

2. The method of claim 1, wherein the 3.8 m integrated slab bottom with surface features is characterized by: The workbench is provided with an I-shaped groove, and the outer circle clamping assembly and the adjusting support assembly are arranged at the I-shaped groove, and the position of the outer circle clamping assembly corresponds to the position of the corner piece; The outer circle clamping assembly comprises a clamping table, a clamping jack, a clamping guide rod, and a clamping plate; The bottom of the clamping table is arranged at the I-shaped groove, the mounting end of the clamping jack is arranged at the end of the clamping table, the clamping plate is arranged at the output end of the clamping jack, and the clamping plate is provided with a through hole through which the clamping guide rod passes; The clamping guide rod is arranged on the clamping table and between the clamping table and the adjusting support assembly; The upper end of the clamping guide rod is provided with a clamping nut.

3. The method of claim 1, wherein the 3.8 m integrated slab bottom with surface features is characterized by: The adjusting support assembly comprises an adjusting table and an adjusting jack; The bottom of the adjusting table is mounted at the I-shaped groove, and the mounting end of the adjusting jack is arranged at the end of the adjusting table The output end of the mounting end of the adjusting jack corresponds to the periphery of the first circular table.

4. The method of claim 1, wherein the 3.8 m integrated slab bottom with surface features is characterized by: The number of T-shaped outer spherical surface pressing assemblies is two.

Images