Processing method of 3.8 m integral box bottom with surface feature structure

Abstract

The invention provides a machining method for a 3.8 m integral box bottom with a surface feature structure, which comprises the following steps: machining an inner shape surface of a product blank, sleeving the machined inner shape of the product blank on an outer shape surface of a tool, and clamping by using a clamping tool, and after clamping is completed, the outer profile of the product is machined in a partitioned mode to remove redundant wall thickness allowance of the profile, the large curved surface of the machining area is divided into a plurality of small curved surfaces, and a T-shaped outer spherical surface pressing mechanism is used in the finish-milling process of the product blank. The method has the beneficial effects that the product structure and size precision characteristics are combined, the technological method design of product machining is reasonably carried out, and the machining quality of the box bottom wall thickness is further controlled by designing the finish-milling machining tool and reasonably dividing the machining molded surface and the finish-milling machining sequence.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing of weak rigid parts, and in particular relates to a processing method of a 3.8m integral box bottom with a surface feature structure. Background Art

[0002] The inner shape of this type of parts is ellipsoidal, with a large end diameter of 3800mm, a height of about 1200mm, a maximum thickness of 15mm, and a thickness of 3mm in the thin area of ​​the part. There are multiple flange holes and flange and flange welding bosses on the spherical surface. It is a typical weak rigid thin-walled product, such as Figure 1 shown.

[0003] It is used for welding and connecting with multiple components. The geometric tolerance and wall thickness of the indirect position have high technical requirements. This part has the following processing difficulties: 1) The whole bottom is spun, and the blank margin is small. The blank spinning accuracy directly affects the machining quality. 2) The box bottom is spun, and the internal stress large surface deviation is large. It is difficult to clamp it to ensure the stability of the machining during machining. 3) In order to ensure the welding quality and weight reduction of the rear box bottom, the wall thickness of the box bottom is extremely high.

[0004] Due to the large diameter of the product, the structural rigidity is extremely poor and the size requirements are high. The processing of the curved wall thickness during the processing is a difficult point in the processing of the product. The large diameter box bottom processing area has a large surface bonding difficulty, and there are few clamping positions on the outer surface. After the surface is partially deformed during processing, it is even more difficult to ensure the wall thickness of the product by turning. Milling processing also faces the problem of unstable wall thickness caused by surface deformation. Invention content In view of this, the present invention aims to propose a processing method for a 3.8m integral box bottom with a surface feature structure to solve at least one technical problem in the background technology.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: A processing method for a 3.8m overall box bottom with a surface feature structure comprises the following steps: processing the inner surface of a product blank, then fitting the processed inner surface of the product blank onto the outer surface of a tooling, and clamping the tooling for support; after clamping, the outer surface of the product is processed in different areas to remove excess wall thickness, and the large curved surface of the processing area is divided into a number of small curved surfaces; a T-shaped outer spherical surface clamping mechanism is used during the fine milling process of the product blank.

[0007] Furthermore, a margin of more than 150 mm is left at the large end of the product blank, and both the outer shape and inner shape of the product have a margin of more than 15 mm. The outer circle of the product blank in the 150mm area at the large end is provided with circumferentially evenly distributed corner pieces for clamping.

[0008] Furthermore, segmentation is performed according to the plane deviation of the segmented small curved surface unit being 2-2.5 mm.

[0009] Furthermore, the clamping tool comprises a base and a clamping structure; A plurality of clamping structures are arranged around the base along the circumference; The clamping structure includes an outer circle clamping assembly, an adjustment support assembly, and a workbench, wherein the outer circle clamping assembly and the adjustment support assembly are arranged on the workbench along the circumference; One end of the workbench is arranged on the base.

[0010] Furthermore, the base is hemispherical, and the bottom is provided with a first frustum corresponding to the rough product and a second frustum for installing the clamping structure.

[0011] The outer diameter of the first frustum of the base corresponds to the inner diameter of the product blank.

[0012] Furthermore, an I-shaped groove is provided on the workbench, and an external circle clamping assembly and an adjustment support assembly are arranged at the I-shaped groove, and the position of the external circle clamping assembly corresponds to the position of the corner piece; The external cylindrical clamping assembly includes a clamping table, a clamping jack, a clamping guide rod, and a clamping plate; The bottom of the clamping platform is arranged at the I-shaped groove, the mounting end of the clamping jack is arranged at the end of the clamping platform, 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 can pass; The clamping guide rod is arranged on the clamping platform and between the clamping platform and the adjustment support assembly; The upper end of the clamping guide rod is provided with a clamping nut.

[0013] Further, the adjustment support assembly includes an adjustment platform and an adjustment jack; The bottom of the adjustment table is installed in the I-shaped groove, and the installation end of the adjustment jack is set at the end of the adjustment table. The output end of the mounting end of the adjusting jack corresponds to the four sides of the first truncated table.

[0014] Furthermore, 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 a first bolt; The end of the T-shaped outer spherical surface pressing assembly is arranged on the base through a second bolt.

[0015] Furthermore, the number of T-shaped outer spherical clamping assemblies is 2.

[0016] Furthermore, the second bolt is a double-row bolt; a plurality of sets of double-row screws are respectively installed on the T-shaped keel and arranged along the spherical surface of the base through the screws. Compared with the prior art, the processing method of a 3.8m integral box bottom with a surface feature structure created by the present invention has the following advantages: 1) Complete tooling design: Since large-diameter spinning bottoms are prone to deformation during the finishing stage, a set of reasonable clamping tools is designed to ensure the stability of the parts processing process in the clamping state. The overall rigidity of the parts is enhanced during the entire processing process, which limits the deformation of the parts to the maximum extent and ensures the work accuracy.

[0017] 2) The method of reasonable partitioning of large surfaces: The spherical surface processing area is large and the single program has a large area of ​​processing, which has the problem of long processing cycles and easy deformation of parts. Therefore, the surface is divided according to the part surface data and the machinable area of ​​the clamping, so that the curvature of the single surface after division changes little, and the wall thickness changes little during the processing.

[0018] Combined with the product structure and dimensional accuracy characteristics, the process method design of product processing is reasonably carried out. The processing quality of the bottom wall thickness of the box is further controlled by designing fine milling tooling and reasonably dividing the processing surface and the fine milling sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0020] Figure 1 A schematic diagram of a product according to an embodiment of the present invention; Figure 2 A schematic top view of a product according to an embodiment of the present invention; Figure 3 A schematic diagram of the use of the clamping structure described in the embodiment of the present invention; Figure 4 A schematic diagram of the clamping structure described in an embodiment of the present invention.

[0021] Description of reference numerals: 1. Base; 2. Workbench; 3. First round table; 4. Second round 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

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0023] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0024] A processing method for a 3.8m integral box bottom with a surface feature structure includes the following steps: after processing the inner surface of the product blank, the inner shape of the product blank that has been processed is mounted on the outer surface of the tooling, and the clamping tooling is used for support. After the clamping is completed, the outer surface of the product is processed in different areas to remove the excess wall thickness of the outer surface, and the large curved surface in the processing area is divided into a number of small curved surfaces. The product blank uses a T-shaped outer spherical clamping mechanism during the fine milling process. A margin of more than 150mm is left at the large end of the product blank, and the product outer and inner shapes both have a margin of more than 15mm. The outer circle of the product blank in the 150mm area of ​​the large end is provided with circumferentially evenly distributed corner pieces 16 for clamping. The segmentation is performed according to the plane deviation of the small curved surface unit after segmentation within 2-2.5mm.

[0025] The clamping tooling includes a base 1 and a clamping structure; a plurality of clamping structures are arranged around the base 1 along the circumference; the clamping structure includes an outer circle clamping assembly, an adjustment support assembly, and a workbench 2, and the outer circle clamping assembly and the adjustment support assembly are arranged on the workbench 2 along the circumference; one end of the workbench 2 is arranged on the base 1.

[0026] The base 1 is hemispherical, and the bottom is provided with a first truncated cone 3 corresponding to the blank product and a second truncated cone 4 for installing the clamping structure. The outer diameter of the first truncated cone 3 of the base 1 corresponds to the inner diameter of the blank product.

[0027] An I-shaped groove 5 is provided on the workbench 2, and an external cylindrical clamping assembly and an adjusting support assembly are arranged at the I-shaped groove 5, and the position of the external cylindrical clamping assembly corresponds to the position of the angle piece 16; the external cylindrical clamping assembly includes a clamping platform 6, a clamping jack 7, a clamping guide rod 8, and a clamping plate 9; the bottom of the clamping platform 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 platform 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 that allows the clamping guide rod 8 to pass through; the clamping guide rod 8 is arranged on the clamping platform 6, and is arranged between the clamping platform 6 and the adjusting support assembly; the upper end of the clamping guide rod 8 is provided with a clamping nut 10.

[0028] The adjustment support assembly includes an adjustment platform 11 and an adjustment jack 12; the bottom of the adjustment platform 11 is installed on the I-shaped groove 5, and the mounting end of the adjustment jack 12 is arranged at the end of the adjustment platform 11. The output end of the mounting end of the adjustment jack 12 corresponds to the four sides of the first truncated table 3.

[0029] The T-shaped outer spherical surface pressing mechanism comprises a plurality of T-shaped keels 13 , which are arranged on the product blank through first bolts 14 ; the end of the T-shaped outer spherical surface pressing assembly is arranged on the base 1 through second bolts 15 .

[0030] The number of the T-shaped outer spherical surface pressing assemblies is 2. The second bolts 15 are double-row bolts; a plurality of sets of double-row screws are respectively installed on the T-shaped keel 13 and are arranged along the spherical surface of the base 1 through the screws.

[0031] Since the thin-walled box bottom is prone to deformation during the finishing stage, in order to ensure the stability of the processing process of the clamped parts, it is necessary to design a set of reasonable clamping tools to enhance the overall rigidity of the parts during the entire processing process, limit the deformation of the parts to the maximum extent, and ensure the processing accuracy, especially in the finishing milling stage, it can effectively control the deformation of the parts and reduce the wall thickness deviation. Reasonably divide the processing surface and divide the large area milling into multiple small milling units. The milling cycle of a single area is short, the deformation is small, and it is easier to ensure the wall thickness tolerance. At the same time, the milling sequence of the small milling unit is reasonably planned to further reduce the impact of product deformation on wall thickness processing.

[0032] Since the large-diameter thin-walled box bottom is prone to deformation during the finishing stage, in order to ensure the stability of the parts processing process in the clamped state, it is necessary to design a set of reasonable clamping tooling to enhance the overall rigidity of the parts during the entire processing process, minimize the large deformation of the parts, and ensure the processing accuracy.

[0033] The product is a sheet metal forming blank, with both the outer and inner shapes having a margin of more than 15mm, and a margin of more than 150mm at the large end of the product blank. In order to facilitate the clamping of subsequent parts, 16 angle pieces 16 evenly distributed along the circumference are welded on the outer circle of the 150mm area of ​​the large end for clamping. The process flow is to process the inner surface of the product first, that is, to process the inner spherical surface of the hemispherical product first, to ensure that the inner surface matches the outer spherical surface of the mold. After processing the inner surface, the processed inner shape of the product is put on the outer surface of the tooling, so that the inner surface of the product and the outer surface of the mold fit closely. After clamping is completed, the outer surface of the product is processed in sections to remove the excess wall thickness margin of the outer shape.

[0034] The bottom of the box is processed first with the inner surface and then with the outer surface. The spherical wall thickness is ensured during the processing of the outer surface. Therefore, the jig adopts the form of an integral inner support jig to support the inner surface. Due to the large fitting area of ​​the inner surface, the parts will have a certain degree of roundness deformation after processing. The assembly of the parts and the jig requires clearance fit to ensure the fit between the inner surface of the parts and the jig. The jig is pressed by the 16 outer circle clamping mechanisms on the outer circle of the tooling to ensure the fit between the parts and the jig. The lower end surface of the product is evenly installed with lower end surface support mechanisms that can freely adjust the upper and lower heights to provide an end surface reference for the product tire installation. At the same time, the large end surface of the part has 16 adjustable support mechanisms. The height is leveled and calibrated before the part is pressed to ensure that the large end surface of the part is horizontal and not skewed after the part is pressed. It can also be used as a top opening mechanism for disassembly and assembly of parts.

[0035] The product's profile is gradually thinned during the fine milling process, but on the outer surface, there is only the large-end pressure plate to fix the spherical surface without more support. During the processing, the spherical surface is prone to slowly deform, affecting the processing quality. Therefore, a T-shaped external spherical clamping mechanism is designed on the outside of the tooling. The device consists of a T-shaped follower body, and its front and rear ends are respectively connected to the workbench 2 and the top surface of the jig by bolts. Multiple sets of double-row screws are installed on the T-shaped keel 13. The screws move along the normal direction of the spherical surface to tighten the parts so that the parts and the jig are further fitted and not loose. Two sets of T-shaped external spherical clamping mechanisms can form a relatively stable spherical processing area to reduce the deformation of parts during the outer shape processing.

[0036] To further control the wall thickness tolerance, the large curved surface in the processing area is divided into several small curved surfaces. In order to take into account the processing efficiency (the surface division should not be too small) and based on the inconsistent characteristics of the ellipsoidal spherical surface, the small curved surface unit plane deviation after division is 2-2.5mm. According to the product processing area (in the area of ​​spherical diameter Φ680-Φ3736).

[0037] Table 1 Axial and circumferential segmentation dimensions of the ellipsoid Serial number Maximum axial segmentation arc length Maximum circumferential arc length Remark 1 125 180 Large end starting diameter Φ3736 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 Small end starting diameter Φ680 The existing processing method is to cut the product axially without an external T-shaped external spherical clamping mechanism, and the axial cutting 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 solution of this application, the maximum and minimum deviation of the wall thickness can be reduced to 1.5mm.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing a 3.8m integral box bottom with a surface feature structure, characterized in that: The method comprises the following steps: after the inner surface of the product blank is processed, the processed inner shape of the product blank is mounted on the outer surface of the tooling, and a clamping tooling is used for clamping. After the clamping is completed, the outer surface of the product is processed in different areas to remove the excess wall thickness, and the large curved surface of the processing area is divided into several small curved surfaces. The product blank uses a T-shaped outer spherical clamping mechanism during the fine milling process.

2. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 1, characterized in that: A margin of more than 150mm is left at the large end of the product blank, and both the outer and inner shapes of the product have a margin of more than 15mm. The outer circle of the product blank in the 150mm area at the large end is provided with circumferentially evenly distributed corner pieces for clamping.

3. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 1, characterized in that: The segmentation is performed according to the plane deviation of the small curved surface unit after segmentation being 2-2.5mm.

4. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 2, characterized in that: The clamping tooling includes a base and a clamping structure; A plurality of clamping structures are arranged around the base along the circumference; The clamping structure includes an outer circle clamping assembly, an adjustment support assembly, and a workbench, wherein the outer circle clamping assembly and the adjustment support assembly are arranged on the workbench along the circumference; One end of the workbench is arranged on the base.

5. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 4, characterized in that: The base is hemispherical, and the bottom is provided with a first truncated table corresponding to the rough product and a second truncated table for installing the clamping structure; The outer diameter of the first frustum of the base corresponds to the inner diameter of the product blank.

6. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 4, characterized in that: An I-shaped groove is provided on the workbench, and an external circle clamping assembly and an adjustment support assembly are arranged at the I-shaped groove, and the position of the external circle clamping assembly corresponds to the position of the angle piece; The external cylindrical clamping assembly includes a clamping table, a clamping jack, a clamping guide rod, and a clamping plate; The bottom of the clamping platform is arranged at the I-shaped groove, the mounting end of the clamping jack is arranged at the end of the clamping platform, 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 can pass; The clamping guide rod is arranged on the clamping platform and between the clamping platform and the adjustment support assembly; The upper end of the clamping guide rod is provided with a clamping nut.

7. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 6, characterized in that: The adjustment support assembly includes an adjustment platform and an adjustment jack; The bottom of the adjustment platform is installed at the I-shaped groove, and the installation end of the adjustment jack is set at the end of the adjustment platform; The output end of the mounting end of the adjusting jack corresponds to the four sides of the first truncated table.

8. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 1, characterized in that: 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 a first bolt; The end of the T-shaped outer spherical surface pressing assembly is arranged on the base through a second bolt.

9. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 8, characterized in that: The number of T-type outer spherical clamping assemblies is 2.

10. The method for processing a 3.8 m integral box bottom with a surface feature structure according to claim 8, characterized in that: The second bolts are double-row bolts; a plurality of sets of double-row screws are respectively installed on the T-shaped keel and are arranged along the spherical surface of the base through the screws.

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