CN113579520B - Preparation method of high-strength small hole for member connection - Google Patents
Preparation method of high-strength small hole for member connection Download PDFInfo
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- CN113579520B CN113579520B CN202110873094.3A CN202110873094A CN113579520B CN 113579520 B CN113579520 B CN 113579520B CN 202110873094 A CN202110873094 A CN 202110873094A CN 113579520 B CN113579520 B CN 113579520B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/38—Removing material by boring or cutting
- B23K26/382—Removing material by boring or cutting by boring
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/60—Preliminary treatment
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
- C21D10/005—Modifying the physical properties by methods other than heat treatment or deformation by laser shock processing
Abstract
The invention belongs to the technical field of hole structure processing and strengthening, and relates to a preparation method of a high-strength small hole for member connection, which comprises the following steps: performing surface impact strengthening treatment on a hole preparation area of a material to be processed by adopting a pulse laser beam to enable the hole preparation area on the surface of the material to be processed to generate macroscopic plastic deformation; and drilling the central position of the pulse laser beam irradiation area by adopting the continuous laser beam to form a hole structure. The method of the invention completes the strengthening treatment of the pore structure before the pore making process, and overcomes the defects of low strength and volatile effect of the pore structure formed by a pure laser drilling method; meanwhile, the unfavorable residual stress hole phenomenon is reasonably utilized, and under the condition that the residual stress hole phenomenon is more obvious, the distribution strength of the residual compressive stress field of the hole wall of the hole structure to be prepared is higher.
Description
Technical Field
The invention belongs to the technical field of hole structure processing and strengthening, and particularly relates to a preparation method of a high-strength small hole for member connection.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
Fasteners are mechanical parts used for fastening connection, and riveting and other connections are often completed through holes in the connection process. In a mechanical device, a hole structure often becomes a fatigue failure prone area due to the existence of a stress concentration effect, and in the current industrial application, technicians often perform extrusion strengthening on the hole structure in a core rod extrusion mode and the like, so that the service performance of the hole structure is improved.
With the development of the industry, the strengthening of the fastening through hole of the thin plate connection such as the aircraft skin is difficult to be carried out due to the limitation of the shape and the size of the hole structure. For example, the through hole depth and the hole diameter of the thin plate are small, and the hard core rod adopted by the conventional hole extrusion technology is difficult to pass through the hole structure smoothly on the premise of not damaging the hole structure. The introduction of high-strength residual compressive stress field distribution into the hole wall of the thin-wall component hole structure becomes a problem to be solved by technical personnel.
Disclosure of Invention
In order to overcome the problems, the invention provides a method for processing high-intensity small holes step by using a double-beam laser. The method can be used for preparing a high-strength small-size pore structure for connecting components.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
in a first aspect of the present invention, there is provided a method for preparing a high-strength eyelet for member connection, comprising:
performing surface impact strengthening treatment on a hole preparation area of a material to be processed by adopting a pulse laser beam to enable the hole preparation area on the surface of the material to be processed to generate macroscopic plastic deformation;
and drilling the central position of the pulse laser beam irradiation area by adopting the continuous laser beam to form a hole structure.
The technical principle of the invention is as follows:
laser light has shown great potential in modern industrial development as a green energy source. The pulsed laser can realize the surface strengthening and modification treatment of the material, in the surface processing process of the pulsed laser, the pulsed laser is induced to form plasma shock waves, and under the force effect formed by the shock waves, the surface strengthening effects such as residual compressive stress introduction, microstructure evolution and the like are generated on the surface of the material; continuous laser generally realizes specific applications such as laser manufacturing, laser welding, laser drilling and the like based on a thermal effect formed by interaction between the continuous laser and a substance. The preparation method of the high-strength small hole takes the surface strengthening of the pulse laser as a core basis, and further achieves the aim of improving the strength of the small hole to be manufactured. In the specific processing process related to the invention, the pulse laser beam firstly acts on a planned hole area of a material to be processed, and high-strength residual compressive stress field distribution is formed on the surface of the material. It is particularly noted that the present invention requires that the residual stress distribution unevenness be increased as much as possible by the residual stress-hole effect, thereby forming a hole-making region having a large stress around the hole and a small stress in the hole.
The residual stress hole effect is a phenomenon of uneven residual stress distribution in a laser irradiation area on the surface of a material after a pulse laser beam acts on the surface of the material. In the laser shock irradiation region, the central position tends to have a lower distribution level of the residual compressive stress with respect to the edge position of the irradiation region.
In the second stage of double-beam hole making, the high-energy beam of continuous laser beam is used to perform laser hole making effect of heat effect accumulation on the central position of the pulse laser beam irradiation area. After this stage is completed, the central position of the pulsed laser beam having a lower level of residual compressive stress distribution forms a small-sized hole structure. The hole making by adopting the laser thermal effect can avoid the damage of the hole making by a mechanical processing mode to the existing residual compressive stress field distribution on the surface of the material, so the hole wall part of the prepared small hole has high-strength residual compressive stress distribution.
In a second aspect of the invention, there is provided a high strength pinhole made by any of the above methods.
In a third aspect of the present invention, there is provided a use of dual beam drilling in the fabrication of a mechanical part, the dual beam drilling comprising: pulse laser surface impact strengthening treatment and continuous laser beam drilling processing.
The invention has the beneficial effects that:
the member connecting small hole manufactured by the method of the invention has the characteristics that:
(1) the size is small, the aperture and the hole depth of the small hole are both small, the aperture is generally not more than 6mm, and the hole depth is generally not more than 3 mm;
(2) the strength is high, the depth of the residual compressive stress layer of the pore wall of the small pore prepared by the method can reach mm magnitude, and the distribution of the residual compressive stress field with higher strength has positive influence on the service performance of the small pore.
The invention is characterized in that:
(1) the full-laser hole making method with double laser beams is provided for the first time, the strengthening treatment of the hole structure is completed before the hole making process, and the defects of low strength and volatile effect of the hole structure formed by a single laser drilling method are overcome;
(2) the unfavorable residual stress hole phenomenon is reasonably utilized, and under the condition that the residual stress hole phenomenon is more obvious, the distribution strength of the residual compressive stress field of the hole wall of the hole structure to be prepared is higher.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic diagram of a residual stress hole phenomenon and a pulsed laser and continuous laser irradiation region involved in the high-intensity small hole preparation principle of the present invention: the distribution state of the residual compressive stress in the irradiation range of the residual stress hole-pulse laser beam is represented as an uneven form of 'weak inside and strong outside'; the double-beam irradiation range-the pulse laser beam irradiation region completely covers the continuous laser beam irradiation region, and the distribution of the large-degree residual compressive stress formed by the material to be processed under the induction of the pulse laser beam (located at the outer side in the pulse laser beam irradiation range) is kept outside the continuous laser irradiation range, and the size of the continuous laser beam irradiation region is basically the same as that of the small hole to be formed.
FIG. 2 is a schematic diagram of a method for preparing a high-intensity pinhole by using dual laser beams according to the present invention: the method comprises the following steps of preparing a thin-wall component to be punched, wherein 1 is a thin-wall component to be punched, 2 is a pulse laser beam, 3 is a schematic diagram of macroscopic plastic deformation of a planned punching area on the surface of a material induced by the pulse laser beam, 4 is a continuous laser beam, and 5 is a forming hole structure corresponding to the size of the continuous laser beam.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
As introduced in the background art, aiming at the difficult problem of introducing the hole extrusion strengthening effect, the invention provides a preparation method of a high-strength small hole for member connection, which specifically comprises the following steps:
1. determining the shape and size of the hole structure to be processed
The shape of the high-strength small hole is circular, and the diameters and the like of the high-strength small hole are determined by technicians according to actual processing requirements.
2. Determining the shape and size of a pulsed laser beam
The steps are established on the premise that the parameters of the pulse laser beam are determined, namely the parameters of the pulse laser such as laser energy, laser wavelength, laser pulse width and the like are determined by technical personnel according to the information such as mechanical property and the like of the material to be processed by combining actual laser impact practical experience.
In the manufacturing process of the double-beam high-intensity small hole, the pulse laser beam is used for presetting the residual compressive stress field in the region to be processed, and a foundation is laid for the characteristic of high intensity of the high-intensity small hole.
The pulsed laser beam is determined to be circular based on the circular shape of the aperture to be processed. The diameter of the pulse laser beam is set to be 2-3 times of the diameter of the small hole to be manufactured.
It should be noted that the center position of the irradiation region of the pulse laser beam is the center of the circle to be used for manufacturing the aperture.
3. Determining shape and size of continuous laser beam
The steps are established on the basis that the parameters of the continuous laser beam are determined, namely the parameters of the laser energy density, the laser wavelength, the laser pulse width and the like of the continuous laser are determined by the prior art personnel according to the information of the mechanical property and the like of the material to be processed by combining the practical laser drilling practical experience.
The continuous laser beam and the pulse laser beam have the same circle center, and the circle centers are the circle centers of the holes to be manufactured.
It is worth mentioning that the continuous laser beam may have the same diameter size as the hole to be formed, but a continuous laser beam with a slightly smaller diameter may be selected according to the actual processing requirements. When the size of the continuous laser beam is slightly smaller, the formed small hole has a certain machining allowance, and technicians can determine the size of the machining allowance according to actual requirements and perform surface finishing treatment on the hole structure formed by laser drilling, so that the shape and the size of the formed small hole meet the machining requirements finally.
4. Hole structure forming processing by determined double laser beam parameters and irradiation positions
The step requires that the determined pulse laser beam parameters and the determined continuous laser beam parameters are adopted to sequentially carry out pulse laser surface shock strengthening treatment and continuous laser drilling treatment on the hole preparation area of the material to be processed.
It should be noted that, the skilled person can select the pulsed laser surface impact strengthening treatment to treat one side or both sides of the intended hole area according to actual needs. The selection can also be made according to the following principle: when the thickness of the sheet material to be processed is not more than 1.5mm, laser shock treatment can be carried out on only one side of the sheet material to be processed; when the thickness of the thin plate material to be processed is in the range of more than 1.5mm and not more than 3mm, the laser shock treatment can be selected to be carried out on both sides of the material to be processed, so that the hole planning region of the thin plate forms enough high residual compressive stress field strength before hole making.
The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.
Example 1:
for example, a circular small hole having a diameter of 2mm was formed in a type 304 austenitic stainless steel plate having a thickness of 2 mm. Determining parameters of a pulse laser beam as laser energy 5J, laser wavelength 1064nm and laser pulse width 18ns, and determining the diameter of the pulse laser beam as 5mm according to the diameter of the small hole to be formed; determiningThe continuous laser beam parameter is the laser energy density 106W/cm2The laser wavelength is 1064nm, the laser pulse width is 1ms, and the diameter of the continuous laser beam is determined to be 1.6mm to ensure the machining allowance of the to-be-formed small hole because the smoothness requirement of the to-be-formed circular small hole wall is higher and the surface roughness is lower than 100 mu m. Performing double-sided laser shock surface strengthening treatment on a hole preparation area of the stainless steel sheet by using the pulse laser beam, and ensuring that the irradiation center of the pulse laser beam is positioned at the circle center of a hole to be formed in the machining process; and carrying out laser drilling treatment on the hole preparation area of the stainless steel sheet by using the continuous laser beam. And finally, carrying out mechanical polishing treatment in the hole wall on the laser-formed small hole of the stainless steel sheet to eliminate machining allowance and meet the finish requirement of the small hole.
And performing wire electrical discharge machining on the small hole formed in the embodiment, exposing the hole wall, and measuring the surface residual stress of the hole wall to be-300 MPa by adopting an X-ray diffraction method, thereby proving that the method forms the high-strength small hole with higher strength residual compressive stress distribution.
Comparative example 1:
for example, a circular small hole having a diameter of 2mm was formed in a type 304 austenitic stainless steel plate having a thickness of 2 mm. Directly adopting continuous laser beam to carry out laser drilling processing, wherein the adopted continuous laser beam parameter is laser energy density 106W/cm2The laser wavelength is 1064nm, the laser pulse width is 1ms, and the diameter of the continuous laser beam is determined to be 1.6mm to ensure the machining allowance of the to-be-formed small hole because the smoothness requirement of the to-be-formed circular small hole wall is higher and the surface roughness is lower than 100 mu m. After the laser-formed hole walls of the stainless steel thin plates were subjected to mechanical polishing treatment in the same manner as in example, the residual stress of the hole walls was measured by wire electrical discharge machining, X-ray diffraction, or other methods. The measurement results show that the residual stress of the pore wall of the small pore in the comparative example is 20MPa, and the pore wall of the small pore prepared by the method in the comparative example is proved not to have the residual compressive stress field distribution.
Therefore, the method of the invention completes the strengthening treatment of the hole structure before the hole making process, and overcomes the defects of low strength and volatile effect of the hole structure formed by a pure laser drilling method; meanwhile, the unfavorable residual stress hole phenomenon is reasonably utilized, and under the condition that the residual stress hole phenomenon is more obvious, the distribution strength of the residual compressive stress field of the hole wall of the hole structure to be prepared is higher.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A method for preparing a high-strength small hole for connecting components is characterized by comprising the following steps:
performing surface impact strengthening treatment on a hole preparation area of a material to be processed by adopting a pulse laser beam, and improving the uneven distribution level of residual stress by means of a residual stress hole effect, so that a hole preparation area with large hole peripheral stress and small hole middle stress is formed, and the hole preparation area on the surface of the material to be processed generates macroscopic plastic deformation; the pore structure is circular; the pulse laser beam is circular; the central position of the irradiation area of the pulse laser beam is the circle center of the intended small hole;
drilling the central position of the pulse laser beam irradiation area by adopting continuous laser beams to form a hole structure; the continuous laser beam and the pulse laser beam have the same circle center, and the circle centers are the circle centers of the small holes to be manufactured.
2. The method of producing a high-strength eyelet for member attachment according to claim 1, wherein the diameter of the pulse laser beam is set to 2 to 3 times the diameter of the eyelet to be produced.
3. A method of making a high intensity orifice for connection of components as claimed in claim 1, wherein the diameter of the continuous laser beam is equal to or less than the diameter of the orifice to be formed.
4. The method of preparing a high-strength eyelet for member attachment according to claim 1, wherein the pulse laser surface impact reinforcement treatment is performed on one side or both sides of the area where the eyelet is to be formed.
5. The method for preparing a high-strength eyelet for member connection according to claim 1, wherein when the thickness of the sheet material to be processed is not more than 1.5mm, the single-sided pulse laser surface impact reinforcement treatment is performed; when the thickness of the thin plate material to be processed is in the range of more than 1.5mm and not more than 3mm, pulse laser surface shock peening treatment is carried out on the two surfaces of the material to be processed.
6. Use of the method according to any one of claims 1 to 5 for the manufacture of mechanical parts.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101024862A (en) * | 2006-09-27 | 2007-08-29 | 江苏大学 | Technical hole wall intensifying method based on laser impaction wave and apparatus |
| CN102517423A (en) * | 2011-12-29 | 2012-06-27 | 江苏大学 | Reinforcement method for small hole |
| CN105880849A (en) * | 2016-06-27 | 2016-08-24 | 哈尔滨工业大学 | Micro-nano machining method and device for laser composite ejection liquid beam |
| CN106319176A (en) * | 2016-09-13 | 2017-01-11 | 江苏大学 | Copious cooling work table, copious cooling laser shock peening experiment system and control method thereof |
| CN107267742A (en) * | 2017-05-18 | 2017-10-20 | 江苏大学 | A kind of different-thickness small-hole components laser shock peening method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080241546A1 (en) * | 2007-03-30 | 2008-10-02 | General Electric Company | Machining features in laser shock peened regions |
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- 2021-07-30 CN CN202110873094.3A patent/CN113579520B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101024862A (en) * | 2006-09-27 | 2007-08-29 | 江苏大学 | Technical hole wall intensifying method based on laser impaction wave and apparatus |
| CN102517423A (en) * | 2011-12-29 | 2012-06-27 | 江苏大学 | Reinforcement method for small hole |
| CN105880849A (en) * | 2016-06-27 | 2016-08-24 | 哈尔滨工业大学 | Micro-nano machining method and device for laser composite ejection liquid beam |
| CN106319176A (en) * | 2016-09-13 | 2017-01-11 | 江苏大学 | Copious cooling work table, copious cooling laser shock peening experiment system and control method thereof |
| CN107267742A (en) * | 2017-05-18 | 2017-10-20 | 江苏大学 | A kind of different-thickness small-hole components laser shock peening method |
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