Machining method for high-hardness thin plate type dense-hole-series part

Abstract

The invention provides a machining method of a high-hardness thin plate type dense hole system part, which comprises the following steps: S1, roughly machining a workpiece, reserving inner and outer circle margins and hole system margins, and releasing residual internal stress; s2, the hole system is subjected to semi-finish machining through low-speed wire cutting, the inner circle of the workpiece is trimmed and cut, all hole sites in the hole system are corrected to be within a preset precision range, and finish reaming allowance is reserved; s3, a tool is used for completely surrounding and fixing the workpiece, a reamer is used for conducting finish reaming machining on the hole system under the constant-temperature cooling condition, a recasting area and a heat affected area generated by low-speed wire cutting are removed, and the final hole diameter and position precision requirements are met; and S4, the tool is dismantled, and the high-hardness thin plate type dense-hole-series part is obtained. A combined machining mode is adopted, various deformation problems are effectively solved, a general technology for effectively controlling position precision is provided for high-hardness thin plate type dense hole series parts, and technical difficulties are overcome for enterprises.

Description

Technical Field

[0001] This invention relates to the field of machining technology, specifically to a machining method for high-hardness thin-plate parts with dense hole systems. Background Technology

[0002] The project consists of thousands of parts. (Positioning accuracy requirement 0.02) A 6mm thick annular sheet composed of pin holes, made of GH4169 nickel-based superalloy. The machining challenges of this part are: it is a thin sheet (diameter-to-thickness ratio greater than 30), the material has high hardness (HRC45), the dense hole system causes plastic deformation and cutting thermal deformation, the material removal rate exceeds 50%, and the release of residual internal stress triggers stress deformation. The design requirement is to control the positional accuracy of the dense hole system within 0.02mm.

[0003] A Chinese patent with publication number CN110977348A discloses a method for improving the machining accuracy of thin-walled parts. It combines and controls aspects such as internal stress relief, machining stress relief, clamping method, tool angle selection, and cutting heat control of thin-walled parts, thereby designing a machining method that effectively overcomes the deformation of thin-walled parts and ensures the machining accuracy of thin-walled parts.

[0004] However, the method for improving the machining accuracy of thin-walled parts disclosed in CN110977348A, as well as the traditional single machining methods of drilling, boring, and reaming, are difficult to eliminate various deformations generated during the machining process: thin-plate parts have large plastic deformation, the tool generates extremely high heat during continuous long-term cutting in the machining of dense hole systems, and after all pin holes are machined, the material removal rate of the parts exceeds 50%, the degree of residual stress deformation is also quite serious, the material properties of the parts themselves are also prone to deformation, and the positional accuracy of the hole system cannot be guaranteed at all. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of this invention is to provide a processing method for high-hardness thin-plate parts with dense hole systems.

[0006] A method for processing high-hardness thin-plate parts with dense hole systems according to the present invention includes:

[0007] Step S1: Roughly machine the workpiece, leaving allowances for the inner and outer circles and the hole system, and release residual internal stress. Step S2: Use slow wire EDM to perform semi-finishing of the hole system, trim the inner circle of the workpiece, correct each hole position in the hole system to the preset accuracy range, and retain the fine reaming allowance. Step S3: Use a tooling fixture to completely surround and fix the workpiece, and use a reamer to perform fine reaming on the hole system under constant temperature cooling conditions to remove the recasting zone and heat-affected zone generated by slow wire cutting, and achieve the final hole diameter and position accuracy requirements. Step S4: Remove the tooling to obtain a high-hardness thin-plate part with a dense hole system.

[0008] Preferably, in step S2, a slow wire EDM machining mode of "cut one and repair six" is used for semi-finishing, and the depth of the maximum heat-affected zone on the workpiece surface is reduced to 15 micrometers.

[0009] Preferably, step S2 further includes, before performing semi-finishing of the hole system using slow wire EDM, performing simulation analysis on the recast layer and heat-affected zone of the workpiece during the machining process using numerical simulation software, and optimizing the machining parameters.

[0010] Preferably, the tooling in step S3 includes a cover plate, a washer ring, and a base plate arranged sequentially from top to bottom; the cover plate is a contoured structure that matches the shape of the workpiece, and the cover plate is provided with guide holes corresponding to the workpiece's hole system, the diameter of the guide holes being larger than the diameter of the high-hardness thin plate type dense hole system part; The workpiece is placed on the base plate, the height of the workpiece is adjusted by the washer, and then the cover plate is placed on the upper surface of the workpiece. The cover plate, washer and base plate are fixed together by axial clamping force, and the fixture completely surrounds and fixes the workpiece.

[0011] Preferably, the workpiece and the cover plate are pre-positioned by a temporary pin.

[0012] Preferably, the reamer is a long-shank reamer, which is used for fine alignment guided by the semi-finished hole.

[0013] Preferably, the processing method for high-hardness thin-plate parts with dense hole systems is carried out in a constant temperature workshop. Before step S1, the workpiece and the processing machine tool are left to stand in the constant temperature workshop until they are fully adapted to the temperature inside the constant temperature workshop.

[0014] Preferably, the machine tool is installed on an independent and stable foundation, and the installation location of the machine tool is far away from the stamping equipment and heavy transport channels.

[0015] Preferably, the rough machining of the workpiece in step S1 includes: roughing on a lathe and finishing on a grinding machine to ensure the flatness and thickness requirements of the part.

[0016] Preferably, in step S3, a cutting fluid constant temperature cooling device is used to cool the machining area of ​​the workpiece, maintain the cutting fluid temperature stable, and reduce temperature fluctuations in the machining environment.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a combined machining process: roughing, slow wire EDM, cold machining after the workpiece is fully enclosed and fixed by a fixture, and fine reaming. The fixture's full enclosure and fixation eliminates plastic deformation and thermal deformation of thin-plate parts during clamping and machining. Combined with a constant-temperature cooling device for the cutting fluid, fine reaming reduces final accuracy deviations caused by machine tool inaccuracies. The extremely high machining precision of slow wire EDM controls the positional accuracy of densely packed holes. By eliminating the recast layer and heat-affected zone caused by electrical discharge during wire EDM, the design requirements for high-hardness thin-plate parts with densely packed holes are ultimately met. This combined machining approach not only effectively solves various deformation problems but also establishes a universal technology for effectively controlling the positional accuracy of high-hardness thin-plate parts with densely packed holes, overcoming technical challenges for enterprises and achieving results that can be accomplished by ordinary production operators. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This invention mainly embodies the process flow diagram of the processing method for high-hardness thin plate parts with dense hole systems; Figure 2 This is a front structural diagram illustrating the main features of the invention: a high-hardness thin-plate part with a dense hole system. Figure 3 This is a side view of a high-hardness thin-plate part with a dense hole system, which is the main feature of this invention. Figure 4 This is a cross-sectional structural diagram of the tooling, which is the main feature of this invention. Figure 5 This is a front structural diagram of the tooling, which is the main feature of this invention.

[0019] The following components are shown in the diagram: 1. Cover plate; 2. Washer ring; 3. Base plate; 4. Temporary pin; 5. Connecting machine tool worktable. Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0021] like Figure 1 As shown, a method for processing a high-hardness thin-plate part with a dense hole system according to the present invention includes: Step S1: Roughly machine the workpiece, leaving allowances for the inner and outer circles and the hole system to prevent the final dimensions from exceeding tolerances due to deformation caused by residual stress, and release residual internal stress; Roughly machine the pin holes of the workpiece to retain a certain allowance and effectively release internal stress.

[0022] Step S2: During the slow wire EDM process, high-energy discharge causes localized heating and rapid cooling of the workpiece, resulting in the formation of a recasting zone and a heat-affected zone on the workpiece surface. The slow wire EDM is used to perform semi-finishing of the hole system and trim the inner circle of the workpiece, correcting each hole position in the hole system to the preset accuracy range and retaining a fine reaming allowance. By using slow wire EDM to leave a fine reaming allowance in the semi-finishing of the hole system, all holes in the hole system are corrected to a very high accuracy range before the final finishing. At the same time, the inner circle of the part is trimmed to ensure the overall positional accuracy of the part.

[0023] Step S3: Use a fixture to completely surround and fix the workpiece, and use a reamer to perform fine reaming on the hole system under constant temperature cooling conditions to remove the recasting zone and heat-affected zone generated by slow wire cutting, and achieve the final hole diameter and position accuracy requirements. Step S4: Remove the tooling to obtain a high-hardness thin-plate part with a dense hole system (e.g., Figure 2 and Figure 3 (As shown).

[0024] This application employs a combined machining approach: roughing, wire EDM, cold machining after securing the workpiece with a fixture, and precision reaming. The fixture eliminates plastic and thermal deformation during clamping and machining of thin-plate parts. Precision reaming, combined with a coolant-controlled cooling system, reduces final accuracy deviations caused by machine tool inaccuracies. The high precision of wire EDM controls the positional accuracy of the dense hole system, eliminating the recast layer and heat-affected zone caused by electrical discharge during wire EDM. This ultimately achieves the design requirements for high-hardness thin-plate parts with dense hole systems. Positional accuracy control of the dense hole system in thin-plate parts involves eliminating and compensating for various deformations during machining, reducing the accumulation of error chains, and meeting the final part design requirements. This combined machining approach not only effectively solves various deformation problems but also explores a universal technology for effectively controlling the positional accuracy of high-hardness thin-plate parts with dense hole systems, overcoming technical challenges for enterprises and achieving results achievable by ordinary production operators.

[0025] In one feasible implementation, step S2 employs a "cut one, repair six" slow wire EDM mode for semi-finishing, reducing the depth of the maximum heat-affected zone on the workpiece surface to 15 micrometers. Numerical simulations of the recast layer and heat-affected zone during the slow wire EDM process using COMSOL simulation software revealed that the heat-affected zone generated by the "cut one, repair three" method ranged from 35 to 45 micrometers, which is basically consistent with the results observed in the metallographic tests of the simulated part (maximum 49.8 micrometers). Further simulations showed that the "cut one, repair six" slow wire EDM method can reduce the depth of the maximum heat-affected zone on the surface to approximately 15 micrometers, effectively reducing the impact of electrical discharge on the microstructure and properties of the base material compared to the conventional "cut one, repair three" method.

[0026] In one feasible implementation, step S2 further includes, before semi-finishing the hole system using slow wire EDM, performing simulation analysis on the recast layer and heat-affected zone of the workpiece during the machining process using numerical simulation software, and optimizing the machining parameters.

[0027] like Figure 4 and Figure 5 As shown, in one feasible implementation, the tooling in step S3 includes a cover plate 1, a washer ring 2, and a base plate 3 arranged sequentially from top to bottom; the cover plate 1 is a contour structure that matches the shape of the workpiece, and the cover plate 1 is provided with guide holes corresponding to the hole system of the workpiece. The diameter of the guide holes is larger than the diameter of the dense hole system parts of high hardness thin plate, so as to ensure that no cutting occurs between the tool and the cover plate 1 during the final fine reaming, and the accuracy of the hole system is not affected.

[0028] Place the workpiece on the base plate 3, adjust the height of the workpiece by using the washer ring 2, then cover the upper surface of the workpiece with the cover plate 1, and fix the cover plate 1, washer ring 2 and base plate 3 into one piece by axial clamping force. The fixture completely surrounds and fixes the workpiece.

[0029] The gasket 2 is placed between the cover plate 1 and the base plate 3, and the gasket 2 allows the base plate 3 to be reused.

[0030] The fixture completely surrounds and fixes the workpiece, and increases the rigidity of the workpiece during machining by using axial clamping force, ensuring that the flatness of the workpiece is not affected by the cutting of the tool and thus does not deform during the machining process.

[0031] The bottom of the base plate 3 is provided with a machine tool worktable 5, through which the tooling can be installed on the machine tool.

[0032] In one feasible implementation, the workpiece and the cover plate 1 are pre-positioned by a temporary pin 4.

[0033] In one feasible implementation, a slender shank reamer is used, which overcomes the problem of the high price of floating reamers. The slender shank reamer is made of carbide and is used for fine reaming with the semi-finished hole as a guide, avoiding damage to the positional accuracy of the original hole system and reducing the final accuracy deviation of the part caused by the accuracy problem of the machine tool itself.

[0034] In one feasible implementation, the machining method for high-hardness thin-plate parts with dense hole systems is carried out in a temperature-controlled workshop. Before step S1, the workpiece and the machine tool are left to stand in the temperature-controlled workshop until they are fully adapted to the temperature. The machining workshop for high-hardness thin-plate parts with dense hole systems should maintain a relatively constant temperature. Temperature changes should be avoided to prevent thermal deformation of the machine tool, workpiece, and measuring tools, which could severely affect accuracy.

[0035] In one feasible implementation, the machine tool is installed on an independent and stable foundation, and the installation location of the machine tool is far away from the stamping equipment and heavy transport channels.

[0036] In one feasible implementation, the rough machining of the workpiece in step S1 includes: ensuring the flatness and thickness requirements of the part by roughing on a lathe and finishing on a grinding machine. During rough machining, because the wall thickness is relatively thin, the flatness and thickness requirements of the workpiece are ensured by roughing on a lathe and finishing on a grinding machine, with a certain allowance left on both the inner and outer circles of the workpiece as the final machining position.

[0037] In one feasible implementation, step S3 employs a cutting fluid constant-temperature cooling device to cool the workpiece's machining area, maintaining a stable cutting fluid temperature and reducing fluctuations in the machining environment temperature. Since the workpiece is a densely packed hole system with a large number of holes, continuous high-speed operation of the machine tool for extended periods can easily lead to spindle overload and the coexistence of spindle and cutting heat, resulting in increased machining environment temperature and causing thermal deformation of the workpiece. Step S3 utilizes a cutting fluid constant-temperature cooling device to cool the workpiece's machining area, ensuring the machine tool's cutting fluid maintains a relatively low liquid temperature during circulation, thus improving the quality of the internal machining environment.

[0038] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0039] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for machining high-hardness thin-plate parts with dense hole systems, characterized in that, include: Step S1: Roughly machine the workpiece, leaving allowances for the inner and outer circles and the hole system, and release residual internal stress. Step S2: Use slow wire EDM to perform semi-finishing of the hole system, trim the inner circle of the workpiece, correct each hole position in the hole system to the preset accuracy range, and retain the fine reaming allowance. Step S3: Use tooling to completely surround and fix the workpiece, and use a reamer to perform fine reaming on the hole system under constant temperature cooling conditions to remove the recasting zone and heat-affected zone generated by slow wire cutting, and achieve the final hole diameter and position accuracy requirements. Step S4: Remove the tooling to obtain a high-hardness thin-plate part with a dense hole system.

2. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 1, characterized in that, In step S2, a "cut one, repair six" slow wire EDM machining mode is used for semi-finishing, and the depth of the maximum heat-affected zone on the workpiece surface is reduced to 15 micrometers.

3. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 2, characterized in that, Step S2 also includes, before using slow wire EDM to semi-finish the hole system, using numerical simulation software to simulate and analyze the recast layer and heat-affected zone of the workpiece during the machining process, and optimizing the machining parameters.

4. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 1, characterized in that, The tooling in step S3 includes a cover plate (1), a washer (2) and a base plate (3) arranged sequentially from top to bottom; the cover plate (1) is a contour structure that matches the shape of the workpiece, and the cover plate (1) is provided with a guide hole corresponding to the hole system of the workpiece, and the diameter of the guide hole is larger than the diameter of the high hardness thin plate type dense hole system part. The workpiece is placed on the base plate (3), the height of the workpiece is adjusted by the washer (2), and then the cover plate (1) is placed on the upper surface of the workpiece. The cover plate (1), washer (2) and base plate (3) are fixed together by axial clamping force, and the fixture completely surrounds and fixes the workpiece.

5. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 4, characterized in that, The workpiece and the cover plate (1) are pre-positioned by a temporary pin (4).

6. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 1, characterized in that, The reamer is a long and thin shank reamer, which is used for fine alignment with the hole formed by semi-finishing.

7. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 1, characterized in that, The machining method for high-hardness thin-plate parts with dense holes is carried out in a constant temperature workshop. Before step S1, the workpiece and the machining tool are left to stand in the constant temperature workshop until they are fully adapted to the temperature inside the workshop.

8. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 1, characterized in that, The machine tool is installed on an independent and stable foundation, and the installation location of the machine tool is far away from the stamping equipment and heavy transport channels.

9. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 1, characterized in that, The rough machining of the workpiece in step S1 includes: roughing on a lathe and finishing on a grinding machine to ensure the flatness and thickness requirements of the part.

10. The processing method for high-hardness thin-plate parts with dense hole systems as described in claim 1, characterized in that, In step S3, a cutting fluid constant temperature cooling device is used to cool the machining area of ​​the workpiece, maintain the cutting fluid temperature stable, and reduce temperature fluctuations in the machining environment.

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