CN113070651A

CN113070651A - Machining process method of large titanium and titanium alloy curved surface component

Info

Publication number: CN113070651A
Application number: CN202110327619.3A
Authority: CN
Inventors: 吕逸帆; 刘希林; 孙建刚; 高福洋
Original assignee: 725th Research Institute of CSIC
Current assignee: Luoyang Shipbuilding Materials Research Institute 725th Research Institute Of China Shipbuilding Corp
Priority date: 2021-03-26
Filing date: 2021-03-26
Publication date: 2021-07-06
Anticipated expiration: 2041-03-26
Also published as: CN113070651B

Abstract

The invention provides a machining process method of a large titanium and titanium alloy curved surface component, which belongs to the technical field of metal material machining process manufacturing, wherein machining is firstly combined with the structural characteristics of a melon petal curved surface, a special tool is manufactured to clamp the melon petal, and the problems of vibration, slippage and the like in the workpiece machining process are solved; then, a regular plane is processed in a small-range area selected by the machining allowance part of the spherical shell to be used as a datum plane or a positioning point, so that the problem of machining positioning datum selection is solved; and finally, the machining precision and the positioning precision of the equipment are utilized by combining the tool and the positioning benchmark, and the machining precision of the workpiece is ensured by being assisted by a corresponding advanced measuring means and the like. The invention is innovated in the aspects of tool design, processing positioning reference selection method and the like, so that the machining precision of large titanium and titanium alloy curved surface components can meet high requirements, and the invention has great guiding significance for guiding the machining of workpieces of the same type.

Description

Machining process method of large titanium and titanium alloy curved surface component

Technical Field

The invention belongs to the technical field of machining process manufacturing of metal materials, and mainly relates to a machining process method of a large member consisting of space curved surfaces.

Background

The titanium and the titanium alloy have the characteristics of small density, high specific strength, good heat resistance, excellent corrosion resistance and the like, so the titanium and the titanium alloy are widely applied to the fields of aviation, aerospace, navigation, petroleum, chemical industry, electric power, medical treatment, sports and the like^[1]. With the increasing use amount of titanium and titanium alloy year by year, corresponding machining parts are increased gradually, and the requirement on machining precision of machined components is higher and higher.

Compared with other metals and alloys thereof, the machining characteristics of titanium and titanium alloys are different, and the main machining characteristics are as follows:

1) titanium and titanium alloy have poor thermal conductivity and high chemical activity, so that the temperature of a tool nose is easily and rapidly increased, the red hardness of the tool edge is reduced, and the tool edge is rapidly worn; and the cutting tool is easy to chemically react with surrounding media to cause cutting oxidation, so that the surface of a workpiece is oxidized and hardened, and the cutting tool is rapidly worn or chipped.

2) Titanium and titanium alloy have small elastic modulus, and are easy to generate larger deformation, rebound, distortion, slippage and vibration in the cutting process, so that the geometric shape of a machined part is poor, the precision is reduced, and the surface roughness is increased.

3) Titanium and titanium alloy are seriously stuck to a cutter in the cutting process because the titanium has high affinity and is easily stuck to a cutting edge in the cutting process, so that the friction force between the cutter and a workpiece is greatly increased, the service life of the cutter is greatly reduced by a large amount of heat generated by friction, and the surface roughness is also increased.

The machining characteristics of titanium and titanium alloy lead to the difficult processing of titanium and titanium alloy, and except for the easily ground cutter, the most difficult control lies in that the workpiece is easy to generate larger deformation, rebound, distortion, slippage and vibration in the cutting process, and the cutter is easy to vibrate, so that the geometric shape of the workpiece is poor, the precision is reduced, and the surface roughness is increased. The common titanium and titanium alloy non-curved surface member has regular structure and smaller specification, so the machining difficulty is easy to solve.

The conventional machining method of titanium and titanium alloy components is as follows:

1) and selecting a proper plane of the part as a reference plane.

2) And carrying out other dimension processing by taking the reference plane as a reference. In the processing process, a cutter with better performance is selected, and simultaneously the feed amount and the processing speed are adjusted to overcome the characteristics of cutter abrasion, cutter vibration, cutter adhesion and the like of titanium and titanium alloy.

3) In the machining process, auxiliary measuring tools (calipers, micrometers and the like) are adopted to measure the machining sizes of the workpieces in time, and the influences of deformation, resilience, distortion, slippage, vibration and the like on the sizes of the workpieces in the machining process of the titanium and titanium alloy workpieces are discovered and solved in time, so that the machining precision of the workpieces is ensured.

The machining method of the traditional titanium and titanium alloy component can not meet the machining quality requirement of the large curved surface component, and the main reasons are as follows:

1) the member has large specification, heavy weight and curved surface structure, and is easy to vibrate and slide in the processing process.

2) Each surface of the member is basically a curved surface structure, and a proper plane is not used as a reference plane.

3) The component does not have a proper auxiliary measuring tool to measure the corresponding curved surface dimension in the machining process.

In view of this, a new machining process for titanium and titanium alloy curved surface members with high precision requirements is urgently needed.

Disclosure of Invention

The invention is innovated in the aspects of tool design, processing positioning reference selection method and the like, and provides a machining process method of large titanium and titanium alloy curved surface components, so that the machining precision of the large titanium and titanium alloy curved surface components can meet high requirements, and the method has great guiding significance for guiding the machining of workpieces of the same type. The invention mainly solves the following problems:

1) vibration, slippage and other problems of the large curved surface member in the processing process;

2) the problem of processing positioning reference selection of a large curved surface component in the processing process is solved;

3) the dimensional accuracy of the large curved surface component in the processing process is controlled.

In order to achieve the purpose, the invention adopts the specific scheme that:

a machining process method of a large titanium and titanium alloy curved surface component is characterized in that the curved surface component is a 1/6 melon petal of a titanium alloy hemispherical shell, and the machining process method comprises the following steps:

firstly, manufacturing a special tool by combining the structural characteristics of the curved surface of the melon petal, and then clamping the melon petal and the tool; the tooling is in contact with the melon petal outer spherical surface, the contact part of the tooling and the melon petal outer spherical surface is spherical, and the contact surface of the tooling and the outer spherical surface are processed with the same radius size;

step two, processing a regular plane as a datum plane or a positioning point in a small-range area selected by the machining allowance part of the spherical shell, wherein the processing positioning datum selection method has two schemes:

the first scheme is as follows: selecting machining positioning references at the machining allowance positions of the inner spherical surface, namely machining 4 positioning references on the inner spherical surface near 4 sharp angles of the melon petals;

scheme II: selecting processing positioning reference at the processing allowance positions of the top end and the bottom end surface of the melon petal;

and thirdly, combining the tool and the positioning benchmark, and ensuring the machining precision of the workpiece by utilizing the machining precision and the positioning precision of the equipment and assisting with a corresponding advanced measurement means.

And selecting the small-range area in the step two after rough machining, reserving the small-range area in the finish machining process, and finally re-machining the small-range area under the condition that all other sizes are machined in place and qualified.

In the third processing step, the key size is positioned in real time by referring to the positioning reference by the positioning accuracy of the equipment; the partial size of the melon flap including the width and the chord length of the truncated edge is directly measured by a caliper, and the melon flap is measured by a three-coordinate measuring instrument when the net size allowance is 1mm in other sizes, and is processed again according to the measurement result.

Further, the machining process method adopts the following scheme:

1) marking the melon segments and giving rough machining allowance;

2) processing the external spherical surface of the melon petal and the spherical surface of the tooling in the same radius size;

3) clamping the melon sections in a tool for rough machining;

4) processing 4 positioning references in a small range area of 4 corners of the melon segment;

5) semi-finishing until the margin of a single side is 1mm, positioning the position of the cutter according to 4 positioning references at any time in the machining process, and reasonably controlling all parameters including the feed amount;

6) detecting each size of the melon petals by a three-coordinate measuring instrument;

7) carrying out melon petal fine machining according to a three-coordinate measurement result, positioning the position of a cutter according to 4 positioning references at any time in the machining process, and reasonably controlling various parameters including the feed amount;

8) and (5) final inspection by the three-coordinate measuring instrument.

Has the advantages that:

the spherical shell melon petal manufactured by the machining process method for the large titanium and titanium alloy components completely meets the requirements of various size indexes of design drawings, and compared with the traditional machining process method, the machining precision is greatly improved.

Drawings

FIG. 1 is a schematic view of a melon petal shape;

FIG. 2 is a schematic view of a melon petal groove;

FIG. 3 is a schematic diagram of the included angle and radius of the two side surfaces of the melon petal groove;

FIG. 4 is a schematic view of a hemispherical shell after assembly welding of the segments;

FIG. 5 is a schematic view of the melon petal assembly; wherein, a) the clearance of the truncated edge (less than or equal to 0.5 mm) and b) the misalignment amount of the truncated edge (less than or equal to 0.5 mm);

FIG. 6 is a schematic view of a melon petal processing tool;

fig. 7 is a schematic view of tooling clamping and melon petal machining positioning.

Supplementary explanation:

FIG. 5 illustrates: two main situations can mainly appear due to the influence of single melon lamella machining precision after 6 melon lamella subassemblies are assembled: in case 1, fig. 5 a), there will be a gap (at the top or bottom) between the 2 groove blunt edges; fig. 5 b) shows that in case 2, the inner and outer spherical surfaces of the 6 melon petals are constrained by the same spherical surface, so that the truncated edges of the 2 grooves are staggered, and the subsequent welding cannot be performed if the staggered edge amount is greater than the width of the truncated edge.

FIG. 7 illustrates: according to the shape of the melon petal, the melon petal clamping can be only carried out on 4 side arc surfaces. When a side cambered surface is processed independently, the clamping device of the side cambered surface needs to be removed, so that when 4 side cambered surfaces are processed in sequence, the clamping device is also removed in sequence and then installed in sequence, the workpiece is likely to be clamped and loosened in the process, and further the workpiece is likely to slide. Therefore, it is necessary to perform the repositioning with reference to 4 positioning references from time to time during the machining process.

Detailed Description

The invention is suitable for machining large titanium and titanium alloy curved surface components.

The equipment required in the process of the machining process method of the large titanium and titanium alloy curved surface component comprises the following steps: machining center, three-coordinate measuring apparatu.

The large curved surface member is 1/6 melon petal of titanium alloy semi-spherical shell, the melon petal is composed of a plurality of curved surfaces, the contour size after finish machining is about 1300 multiplied by 1100 multiplied by delta mm, the weight is hundreds of kilograms, and the shape schematic diagram of the melon petal member is shown in figure 1. The two side surfaces of the melon sections are provided with butt welding grooves, and the shape and the size of the grooves are shown in attached figures 2 and 3. After finishing, 6 melon petals are assembled and welded into a hemispherical shell with the radius of about phi 1000mm, as shown in figure 4.

The machining characteristics and difficulty of the titanium alloy melon petal component mainly comprise:

1) the melon petal has large shape and specification, heavy weight and curved surface structure, and is very easy to vibrate and slide in the processing process.

As can be seen from the attached figures 1-4, the inner surface and the outer surface of the melon petal are spherical surfaces, the top end surface is a cylindrical surface vertical to the equatorial plane, the bottom end surface is an equatorial torus, the included angle of the slope surface space on the two sides is 60 degrees, the truncated cone curve is a section of circular arc, and the circular arc is concentric with the inner spherical surface and the outer spherical surface of the melon petal. The surfaces of the melon petal components form an angle and are mutually restricted to form a complex space structure. Because the melon lamella is big, weight is big, and titanium alloy characteristics such as processing easy vibration, shake sword etc. are added to again, these all can cause the stability of melon lamella machine tooling in-process work piece poor, and very easy vibration, slip bring very big degree of difficulty for machining precision control.

2) The melon petal itself has no proper processing positioning datum plane to choose.

The melon petal curved surfaces form angles with each other and are constrained with each other, and a conventional proper plane is not used as a reference plane.

3) The melon lamella groove preparation precision requires highly.

The part that the melon lamella processing degree of difficulty is the processing of both sides groove blunt edge, mainly shows as follows:

a) as can be seen from fig. 2, the bevel blunt radius: r1016 +/-0.1 mm; groove blunt edge width: 2 plus or minus 0.1 mm;

b) as can be seen from fig. 3, the included angle of the truncated edges at the two sides of the groove is 60 degrees; the truncated circular arc of the groove is concentric with the inner and outer spherical surfaces of the melon petal.

The assembly welding of follow-up 6 melon lamella must be considered in single melon lamella processing, and the groove design scheme requires that the groove truncated edge is seamless butt joint, so, although there is not strict tolerance requirement to groove truncated edge contained angle and concentricity, receive the assembly constraint of 6 melon lamella. The assembly requirements after processing of 6 melon petals are shown in the attached figure 5, and are as follows:

a) the deviation of the radius (about R1000 mm) of the hemispherical shell is less than or equal to 1 mm;

b) the maximum gap between the truncated edges of any two melon petal grooves is less than or equal to 0.5 mm;

c) the maximum misalignment amount of the truncated edges of any two melon-petal grooves is less than or equal to 0.5 mm.

d) If the deviation of the included angle alpha of the two grooves is overlarge, the development of subsequent welding work can be influenced, and even the welding quality is influenced.

The assembly precision requirement is high, so the machining precision of a single melon petal must be strictly controlled, and particularly the sizes of the truncated radius R1016mm, the included angle of two grooves on the single melon petal of 60 degrees, the included angle alpha of the two adjacent grooves of the two melon petals, and the concentricity of the truncated circular arc and the inner and outer spherical surfaces are precisely controlled.

Aiming at the processing characteristics and difficulty of the melon segments, the following measures are mainly adopted for solving the problems:

1) the special tool is manufactured by combining the structural characteristics of the melon petal curved surface, so that the problems of vibration, slippage and the like in the workpiece machining process are solved.

The special tool designed and manufactured is shown in the attached figure 6. Because melon lamella itself is great, weight is heavier, so the frock of preparation also should be great relatively and require the rigidity better to guarantee the stability of work piece in the course of working. Frock and melon lamella insert contact, the two contact segment is the sphere, and the frock contact surface is processed with the same radius size with insert, can make the two contact with the face like this to avoid point or line contact.

The tool design and manufacturing method can ensure the stability of the melon-petal component in the machining process and prevent the vibration and the slippage of the workpiece. The melon segments and the tooling are clamped as shown in the attached figure 7.

2) And processing a regular plane as a reference plane or a positioning point in a small-range area selected from the machining allowance part of the spherical shell.

The processing positioning reference selection method is shown in the attached figure 7:

the first scheme is as follows: and (3) selecting a machining positioning reference at the machining allowance position of the inner spherical surface, namely machining 4 positioning references on the inner spherical surface near 4 sharp angles of the melon petal, such as A, B, C, D position in the attached drawing 7.

Scheme II: and (4) selecting processing positioning benchmarks at the processing allowance positions of the top end and the bottom end surfaces of the melon petals, as shown by the position E, F, G, H in the attached figure 7.

By adopting the method to select the machining positioning reference, even if the workpiece has vibration, sliding and other conditions in the machining process, the relative positions of the 4 machining references can be ensured to be fixed, and the machining precision of the size of the workpiece can be ensured by constantly referring to the 4 positioning references to update and position in the machining process. The small-range local area can be selected after rough machining, then reserved in the fine machining process, and finally re-machined under the condition that all other sizes are machined in place and qualified.

3) The machining precision of the workpiece is ensured by combining the tool and the positioning reference, utilizing the machining precision and the positioning precision of the equipment and assisting corresponding advanced measuring means and the like.

The machining equipment selects a machining center with high machining precision to mill the workpiece, and the positioning precision of the equipment is used for positioning critical dimensions such as grooves and the like in real time according to the positioning reference in the machining process. The partial size of the melon lamella such as 2mm of truncated width and chord length can be directly measured by calipers and the like, and other sizes can be measured by an advanced three-coordinate measuring instrument when the net size allowance is about 1mm, and are processed again according to the measurement result, so that the processing precision is ensured.

The machining scheme of the large titanium alloy curved surface component melon petal is as follows:

1) and marking the melon segments and giving rough machining allowance.

2) And processing the external spherical surface of the melon petal and the spherical surface of the tool with the same radius.

3) And (5) clamping the melon sections in the tooling for rough machining.

4) 4 positioning references are processed in a small range area of 4 corners of the melon flap.

5) Semi-finishing to about 1mm of unilateral allowance, positioning the position of the cutter according to 4 positioning references at any time in the machining process, and reasonably controlling parameters such as the feed amount.

6) And detecting each size of the melon petals by a three-coordinate measuring instrument.

7) And carrying out melon petal fine machining according to a three-coordinate measuring result, positioning the position of the cutter according to 4 positioning references at any time in the machining process, and reasonably controlling parameters such as the feed amount.

8) And (5) final inspection by the three-coordinate measuring instrument.

The spherical shell melon petal manufactured by the machining process method of the large titanium and titanium alloy component completely meets the requirements of various size indexes of design drawings. The machining accuracy ratio of the present invention to the conventional machining process is shown in table 1.

Table 1: the precision of the invention is compared with the precision of the traditional machining process.

As can be seen from table 1, the precision of the machining method of the present invention is greatly improved over the precision of the conventional machining method. The traditional machining method has overlarge size deviation after assembly, for example, the truncated edge misalignment amount reaches 3mm and is larger than the truncated edge width by 2mm, and the welding requirements of 6 subsequent melon petals cannot be met.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

Example 1:

the invention has been applied to the manufacture of Ti80 titanium alloy semispherical shell with phi 2200mm specification. The hemispherical shell is formed by separately processing 6 melon petals, then assembling and welding.

The machining scheme of the melon petal of the titanium alloy curved surface component is as follows:

1) and marking the melon segments and giving rough machining allowance.

3) And (5) clamping the melon sections in the tooling for rough machining.

5) Semi-finishing till the unilateral allowance is 1mm, positioning the cutter position according to 4 positioning references at any time in the machining process, and reasonably controlling parameters such as the feed amount.

8) And (5) final inspection by the three-coordinate measuring instrument.

The measured data of the single finished and 6 assembled main sizes of the Ti80 alloy melon petals are shown in the table 2, and the test results completely meet the design tolerance requirements.

Table 2: the Ti80 alloy melon petals were individually finished and 6 measured dimensions after assembly.

Example 2:

the invention has been applied to the manufacture of TC4 titanium alloy spherical cap end sockets with the specification of phi 2800 mm. The spherical cap end socket is formed by separately processing 6 melon petals, then assembling and welding.

The machining scheme of the titanium alloy curved surface component elliptical seal head is as follows:

1) and marking the melon segments and giving rough machining allowance.

2) The outer surface of the melon segment and the tooling surface are processed in the same radius size.

3) And (5) clamping the melon sections in the tooling for rough machining.

8) And (5) final inspection by the three-coordinate measuring instrument.

The actual measurement data of the main sizes of the TC4 titanium alloy melon petals after single finish machining and 6 assembling are shown in the table 3, and the test results completely meet the design tolerance requirements.

Table 3: TC4 alloy melon petals were individually finished and 6 measured dimensions after assembly.

It should be noted that the above-mentioned embodiments illustrate rather than limit the scope of the invention, which is defined by the appended claims. It will be apparent to those skilled in the art that certain insubstantial modifications and adaptations of the present invention can be made without departing from the spirit and scope of the invention.

Claims

1. The machining process method of the large titanium and titanium alloy curved surface component is characterized in that: the curved surface component is 1/6 melon petals of a hemispherical shell, and the machining process method comprises the following steps:

2. The machining process of claim 1, wherein: and step two, selecting the small-range area after rough machining, then reserving the small-range area in the finish machining process, and finally, reprocessing the small-range area under the condition that all other sizes are processed in place and qualified.

3. The machining process of claim 1, wherein: in the third processing step, the key size is positioned in real time by using the positioning precision of the equipment per se and referring to the positioning reference; the partial size of the melon flap including the width and the chord length of the truncated edge is directly measured by a caliper, and the melon flap is measured by a three-coordinate measuring instrument when the net size allowance is 1mm in other sizes, and is processed again according to the measurement result.

4. The machining process of claim 1, wherein: the machining process method comprises the following specific scheme:

1) marking the melon segments and giving rough machining allowance;

3) clamping the melon sections in a tool for rough machining;

8) and (5) final inspection by the three-coordinate measuring instrument.