Machining method for deep hole

Abstract

The invention discloses a machining method for a deep hole. The machining method comprises the steps that two guide holes are oppositely machined in the two sides of a workpiece to be machined; drilling towards the center of the workpiece through the guide holes in the two sides to form two holes with the first hole diameter, and communicating the two holes to form a through hole; reaming the through hole from the first hole diameter to a second hole diameter by adopting a stepped gun drill; the through hole is reversely and roughly bored and reamed through a pull boring cutter, and the hole diameter of the through hole is enlarged to a third hole diameter from a second hole diameter; and fine boring and chambering are conducted on the through hole through a pull boring head, and the hole diameter of the through hole is expanded to a fourth hole diameter from a third hole diameter. According to the machining method for the deep holes, firstly, the gun drill is adopted for drilling the small-diameter deep holes with the half depth from the two ends of the workpiece correspondingly and communicating the small-diameter deep holes, then the stepped gun drill is used for chambering machining, misalignment steps in pipe holes formed in the previous steps are reduced, and finally tolerance is approached in a multi-step layered broaching boring machining mode; and finally, deep holes meeting the requirements are formed through machining.

Description

Technical Field

[0001] The present invention relates to the field of processing deep holes with a large aspect ratio, and in particular to a processing method for deep holes. Background Art

[0002] In the field of machining, when processing deep hole parts with a total length of more than 1.5 meters, a length-to-diameter ratio of 80:1, and an extreme hole bridge (hole bridge as small as 1.9mm), the existing deep hole processing methods can no longer meet the requirements of processing accuracy.

[0003] The existing processing method is to divide the workpiece into multiple sections, punch holes in each section, and then weld each section in pairs to form a whole piece of material. However, due to the small hole bridge, the welding deformation can only be controlled by laser welding inside the tube hole. However, whether it is processed by gun drilling or BTA (Boring and Trepanning Association, deep hole drilling) mode, due to the small hole bridge between adjacent tube holes and the influence of hand material removal strength, the tube holes processed first can ensure good verticality, while the verticality of the subsequent tube holes cannot be guaranteed.

[0004] Therefore, a new deep hole processing method is needed to achieve deep hole processing while ensuring the tube hole processing accuracy and hole bridge clearance. Summary of the invention

[0005] The object of the present invention is to provide a deep hole processing method, which has the advantage of high deep hole processing accuracy.

[0006] To achieve the above object, the present invention provides a deep hole processing method, which comprises:

[0007] S10, machining two guide holes on opposite sides of the workpiece to be machined;

[0008] S20, drilling holes toward the center of the workpiece through the guide holes on both sides to form two holes of the first aperture and connecting them to form a through hole;

[0009] S30, using a step gun drill to expand the through hole from the first hole diameter to a second hole diameter;

[0010] S40, using a boring tool to perform reverse rough boring and expansion on the through hole, so that the aperture of the through hole is expanded from the second aperture to a third aperture;

[0011] S50, using a boring head to perform precision boring and expansion on the through hole, and the aperture of the through hole is expanded from the third aperture to a fourth aperture.

[0012] Optionally, the difference between the second aperture and the first aperture is the first hole expansion amount, the difference between the third aperture and the second aperture is the second hole expansion amount, and the difference between the fourth aperture and the third aperture is the third hole expansion amount; the first hole expansion amount is greater than the second hole expansion amount, and the second hole expansion amount is greater than or equal to the third hole expansion amount.

[0013] Optionally, the first aperture is 18 mm, the second aperture is 18.5 mm, the third aperture is 18.9 mm, and the fourth aperture is 19.1 mm.

[0014] Optionally, after step S50, the method further includes:

[0015] S60, using an inner diameter gauge to detect the inner diameter of the through hole, and testing whether the detection mandrel can pass through the through hole. If the detection mandrel can pass through the through hole, stop processing; if the detection mandrel cannot pass through the through hole, continue to use a boring tool to expand the through hole, and expand the aperture of the through hole from the fourth aperture to the fifth aperture.

[0016] Optionally, the difference between the fifth aperture and the fourth aperture is a fourth hole expansion amount, and the fourth hole expansion amount is less than or equal to the third hole expansion amount.

[0017] Optionally, the fifth aperture is 19.15 mm.

[0018] Optionally, after step S60, the method further includes:

[0019] S70, performing inner hole honing on the through hole.

[0020] Optionally, in step S20, a gun drill is used to drill holes from the guide holes at both ends of the workpiece toward the center.

[0021] Optionally, in step S10, the diameter of the guide hole is the same as the first diameter, and the depth of the guide hole is 25 mm.

[0022] Optionally, before step S10, the method further includes:

[0023] S01. Pre-processing the workpiece to form two parallel surfaces on both side surfaces where guide holes are to be drilled.

[0024] In summary, compared with the prior art, the deep hole processing method provided by the present invention has the following beneficial effects:

[0025] The deep hole processing method of the present invention first uses a gun drill to drill small-diameter deep holes of half the depth from both ends of the workpiece and connect them, then uses a step gun drill to expand the hole to reduce the staggered steps in the tube hole formed in the previous steps, and finally approaches the tolerance through a multi-step layered broaching and boring process to finally form a deep hole that meets the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flow chart of a deep hole processing method.

[0027] Figure 2 Schematic diagram of a workpiece processed in the present invention.

[0028] Description of reference numerals:

[0029] Workpiece 10

[0030] Through hole 110 DETAILED DESCRIPTION

[0031] The following will be combined with the attached embodiment of the present invention Figure 1 ~Attached Figure 2 , the technical solutions, structural features, objectives achieved and effects in the embodiments of the present invention are described in detail.

[0032] It should be noted that the drawings are in a very simplified form and use non-precise proportions. They are only used to conveniently and clearly assist in explaining the embodiments of the present invention, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention.

[0033] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only the elements explicitly listed, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0034] like Figure 1 As shown, the present invention provides a method for processing deep holes, the processing method comprising the following steps:

[0035] S10, two guide holes are machined on both sides of the workpiece 10 to be machined. In this embodiment, the guide holes are blind holes with a diameter of 18 mm and a depth of 25 mm-30 mm. The guide holes are obtained by clamping the workpiece 10 on a milling machine and milling to ensure the machining accuracy of the guide holes. The guide holes are used for the subsequent gun drill bit to be placed in order to perform initial machining drill bit positioning.

[0036] S20, drilling two holes of the first aperture through the guide holes at both sides to the center of the workpiece 10 respectively and connecting them to form a through hole 110. In this embodiment, a gun drill is used to drill holes through the guide holes at both ends of the workpiece 10 to the center, and the first aperture is 18 mm.

[0037] S30, using a step gun drill to expand the through hole 110 from the first hole diameter to the second hole diameter. In this embodiment, the second hole diameter is 18.5 mm. The front end of the step gun drill used in this step has a step of D17 mm. Before using the step gun drill to expand the hole, as a preferred embodiment, it also includes deep boring and milling guide holes on the surfaces of both ends of the workpiece 10 to expand the diameter of the guide holes to The depth of the guide hole is bored and milled to 100 mm. On this basis, the through hole 110 formed in S20 is expanded by a step gun drill, so that the hole diameter is expanded from 18 mm to 18.5 mm. The expansion process of this step can reduce the misalignment step in the pipe hole formed due to the verticality error in the previous process.

[0038] S40, using a boring tool to perform reverse rough boring and expansion of the through hole 110, the aperture of the through hole 110 is expanded from the second aperture to the third aperture. The boring tool performs reverse boring and rough boring on the through hole 110 at a boring speed of 20 to 25 mm / min to bore and expand the hole to a third hole diameter of 18.9 mm.

[0039] Reverse broaching and boring means that the feed direction of the broaching and boring tool is opposite to the drilling direction of the gun drill in the previous step. During the gun drilling process, due to the slender structure of the drill bit itself and the fact that the drill bit is working against the material being drilled, the drill bit will be subjected to a force perpendicular to the drilling direction. The slender structure of the drill rod itself leads to its limited rigidity. The drill rod is bound to bend during the drilling process, resulting in vertical deviations in the holes processed by the drill bit. The broaching and boring process is similar to the cold drawing process. The reverse broaching tool rod has no deflection, so reverse broaching can better ensure the straightness and verticality of the processed pipe hole. This can further remove the misaligned steps formed during the S20 process.

[0040] S50, using a boring head to perform precision boring and expansion of the through hole 110, and the aperture of the through hole 110 is expanded from the third aperture to the fourth aperture. In this embodiment, the boring head is used to perform precision boring and expansion at a broaching speed of 10 to 15 mm / min, and the fourth aperture is 19.1 mm, gradually approaching the target aperture of the through hole 110 and the hole bridge tolerance between the through holes 110.

[0041] After step S50, the method further includes:

[0042] S60. Use an inner diameter gauge to detect the inner diameter of the through hole 110, and test whether the test mandrel can pass through the through hole 110. If the test mandrel can pass through the through hole 110, stop processing; if the test mandrel cannot pass through the through hole 110, continue to use the boring tool to expand the through hole 110, and expand the aperture of the through hole 110 from the fourth aperture to the fifth aperture. The test mandrel is a standard mandrel, which is used to test whether the processed inner hole meets the use requirements. Use the inner diameter gauge and the test mandrel to ensure the roughness of the inner wall of the through hole 110 and whether the tube is passed smoothly. If the test mandrel cannot pass through the tube smoothly, continue to use it. The through hole 110 is finished with a boring tool.

[0043] After step S60, the method further includes:

[0044] S70, honing the inner hole of the through hole 110. The inner hole honing process is used to remove the vibration marks, fine burrs, etc. on the inner wall of the tube hole during the processing, and reduce the roughness of the inner wall of the tube hole. Figure 2 shown.

[0045] In this embodiment, as a preferred solution, before step S10, the following is further included:

[0046] S01, pre-processing the workpiece 10, processing two parallel surfaces on the two sides of the surface where the guide hole is to be drilled. The initial state of the workpiece 10 is The round bar forging is firstly rough milled into an octagon with balanced allowance on each surface. During the rough machining process, the cutting parameters S=1800rpm, F=2200mm / min can be selected, that is, the spindle speed is 1800 rpm, and the cutting feed rate is 2200mm / min. In the process of pre-machining the workpiece 10, it is recommended to use a small diameter tool (for example, tool diameter D=20mm, spindle speed S=2500rpm) for pre-machining, with a small cutting depth (for example, 0.2mm), a large feed rate (for example, 100mm / min), and a mode commonly known as "flying knife" to complete the final pre-machining. In addition, in pre-machining, do not use a face milling cutter disc. Although the face milling cutter disc can greatly improve the cutting efficiency, the processing of stainless steel materials itself is more likely to cause cutting deformation, and the stress accumulated in the forging rod during the forging and heat treatment stages makes it impossible to ensure a good flatness during rough machining, which is not conducive to ensuring the subsequent machining accuracy. Therefore, do not use a face milling cutter disc for rough machining.

[0047] After pre-processing, the workpiece 10 is placed for aging treatment, and after the residual stress formed during the internal pre-processing process is eliminated, it is transferred to the processing table to calibrate the reference and then perform subsequent drilling processing.

[0048] The difference between the second aperture and the first aperture is the first hole expansion amount, the difference between the third aperture and the second aperture is the second hole expansion amount, and the difference between the fourth aperture and the third aperture is the third hole expansion amount; the first hole expansion amount is greater than the second hole expansion amount, and the second hole expansion amount is greater than or equal to the third hole expansion amount. The difference between the fifth aperture and the fourth aperture is the fourth hole expansion amount, and the fourth hole expansion amount is less than or equal to the third hole expansion amount. The hole expansion amount gradually decreases with the improvement of the processing accuracy, and the processing accuracy of the through hole 110 is gradually improved, so that the aperture of the through hole 110 gradually approaches the target size.

[0049] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for processing deep holes, characterized in that: The processing method comprises: S10, machining two guide holes on opposite sides of the workpiece to be machined; S20, drilling holes toward the center of the workpiece through the guide holes on both sides to form two holes of the first aperture and connecting them to form a through hole; S30, using a step gun drill to expand the through hole from the first hole diameter to a second hole diameter; S40, using a boring tool to perform reverse rough boring and expansion on the through hole, so that the aperture of the through hole is expanded from the second aperture to a third aperture; S50, using a boring head to perform precision boring and expansion on the through hole, and the aperture of the through hole is expanded from the third aperture to a fourth aperture.

2. The deep hole processing method according to claim 1, characterized in that: The difference between the second aperture and the first aperture is the first hole expansion amount, the difference between the third aperture and the second aperture is the second hole expansion amount, and the difference between the fourth aperture and the third aperture is the third hole expansion amount; the first hole expansion amount is greater than the second hole expansion amount, and the second hole expansion amount is greater than or equal to the third hole expansion amount.

3. The deep hole processing method according to claim 2, characterized in that: The first aperture is 18 mm, the second aperture is 18.5 mm, the third aperture is 18.9 mm, and the fourth aperture is 19.1 mm.

4. The deep hole processing method according to claim 3, characterized in that: After step S50, the method further includes: S60, using an inner diameter gauge to detect the inner diameter of the through hole, and testing whether the detection mandrel can pass through the through hole. If the detection mandrel can pass through the through hole, stop processing; if the detection mandrel cannot pass through the through hole, continue to use a boring tool to expand the through hole, and expand the aperture of the through hole from the fourth aperture to the fifth aperture.

5. The deep hole processing method according to claim 4, characterized in that: The difference between the fifth aperture and the fourth aperture is a fourth hole expansion amount, and the fourth hole expansion amount is less than or equal to the third hole expansion amount.

6. The deep hole processing method according to claim 5, characterized in that: The fifth aperture is 19.15 mm.

7. The deep hole processing method according to claim 4, characterized in that: After step S60, the method further includes: S70, performing inner hole honing on the through hole.

8. The deep hole processing method according to claim 1, characterized in that: In step S20, a gun drill is used to drill holes from the guide holes passing through the two ends of the workpiece toward the center.

9. The deep hole processing method according to claim 1, characterized in that: In step S10, the diameter of the guide hole is the same as the first diameter, and the depth of the guide hole is 25 mm.

10. The deep hole processing method according to claim 9, characterized in that: Before step S10, the method further includes: S01. Pre-processing the workpiece to form two parallel surfaces on both side surfaces where guide holes are to be drilled.

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