Machining process for precise deep-hole part

Abstract

The invention discloses a machining technology of a precise deep hole part. The machining technology comprises the following steps that S10, blanking is conducted; s20, solid solution aging; s30, roughly turning an outer circle and chamfering; s40, a middle hole is drilled through a gun; s50, roughly turning the appearance; s60, stress relief aging is carried out; s70, roughly turning the outer circle; s80, the small end is subjected to semi-finish turning; s90, the large end is subjected to semi-finish turning; s100, honing an inner hole; s110, the outer circle is finely ground; and S120, the two ends are subjected to finish turning, and the precise deep hole part is obtained. Compared with the prior art, the technology has the following beneficial effects that 1, the technology is adopted for machining, and the requirement for the coaxiality of 0.02-0.03 of the outer circle of a deep hole in a drawing can be met after machining; 2, the coaxiality of the center hole and the outer circle after gun drill machining can be effectively rectified by adopting the expansion sleeve clamp to roughly turn the outer circle, the subsequent outer circle grinding allowance is reduced, and the machining efficiency is improved;

Description

Technical Field

[0001] This invention belongs to the field of deep hole machining technology for difficult-to-machine materials, and specifically relates to a machining process for precision deep hole parts. Background Technology

[0002] Precipitation-hardening stainless steel possesses comprehensive properties such as high strength, high toughness, high corrosion resistance, and high oxidation resistance, and is widely used in the manufacture of key equipment in aerospace, petroleum, chemical, and power industries. However, due to its high hardness, good toughness, and poor thermal conductivity, this material is prone to work hardening during processing, increasing the difficulty of machining.

[0003] Meanwhile, for deep-hole structural parts with a length-to-diameter ratio of 6 to 20, insufficient tool holder rigidity leads to vibration, heat accumulation during cutting, difficulty in chip removal, and the inability to directly observe the cutting state. For products with high requirements for deep hole diameter and outer diameter tolerances and high surface finish, such as axial holes of shafts and piston cylinders in multi-stage transmission devices, traditional machining methods involve gun drilling followed by machining on a horizontal machining center using a compound reamer or special boring tool. This often results in poor chip removal, excessive coaxiality, and scratches on the inner hole surface. Moreover, the cost of using such special tools remains high. For difficult-to-machine materials with poor machinability and parts with deep holes requiring a coaxiality of 0.02 to 0.03 on the outer diameter, machining quality issues become even more prominent, often posing a major challenge in production.

[0004] Based on the above situation, this invention designs a precision deep hole part machining fixture and a deep hole part machining process and fixture. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention provides a precision deep hole part machining fixture and deep hole part machining process, which improves the machining process of this type of deep hole part, enhances surface finish, meets the requirement of 0.02 to 0.03 coaxiality of the outer diameter of the deep hole in the product drawing, avoids the use of various custom-made special reamers and special boring tools, and reduces tool usage costs.

[0006] The present invention is solved by the following technical solution.

[0007] A machining process for precision deep-hole parts includes the following steps:

[0008] S10: Cutting: Cutting cylindrical blanks into blanks of specified lengths for processing;

[0009] S20: Solution Aging: The blank to be processed in step S10 is subjected to solution aging treatment. This treatment adjusts the microstructure of the blank and controls the precipitated phases to improve its strength, hardness, and corrosion resistance. The process parameters for solution aging are as follows: Quenching 1040±10℃

[0010] *140min, tempering at 660±20℃*180min;

[0011] S30: Rough turning of outer diameter and chamfering: Chamfering is done on both ends of the blank to be processed after solution aging treatment in step S20 to obtain the blank to be processed after rough turning of outer diameter and chamfering, which is used for positioning of gun drill in subsequent process.

[0012] S40: Gun drilling the center hole: Gun drilling the center hole of the blank to be processed after rough turning the outer circle and chamfering in step S30, to obtain the blank to be processed after gun drilling the center hole; according to the finished size of the deep hole part, leave a machining allowance of 0.08~0.1mm on the outer surface for subsequent processing.

[0013] S50: Rough turning of the shape: The blank to be processed after the gun drilling of the middle hole in step S40 is efficiently removed from the outer surface of the blank to be processed to obtain the blank to be processed with the removed material.

[0014] S60: Stress relief aging: Remove the processing stress generated by the rough machining of the blank in step S50 to obtain a stress-relieved blank. The specific process parameters of the stress relief aging are as follows: temperature 500℃, time: 180 minutes.

[0015] S70: Rough turning of the outer diameter: Position the center hole of the stress-relieved blank to be machined by the gun drill in step S60, tighten the center hole with the expansion sleeve clamp, and use the self-centering jaws to clamp the large end outer diameter of the stress-relieved blank to be machined on the CNC lathe to rough turn the small end outer diameter. Leave a machining allowance of 0.1 to 0.15 mm on the small end outer diameter for subsequent machining, and obtain the blank to be machined with rough turned outer diameter;

[0016] S80: Semi-finish turning of the small end: The small end of the blank to be machined, which is held by the rough turning of the outer circle in step S70, is machined on a CNC lathe to obtain a blank to be machined with a small end relief groove. The relief groove is machined to avoid tool collision in subsequent machining.

[0017] S90: Semi-finish turning of the large end: The outer diameter of the small end of the blank to be machined is machined by CNC turning of the outer diameter of the large end, and the outer diameter of the large end is obtained. A machining allowance of 0.1 to 0.15 mm is left for subsequent machining of the outer diameter of the large end.

[0018] S100: Honing the inner hole: The outer circle of the small end of the blank to be processed in step 90 is held by a spring clip and axially positioned by the shoulder surface of the large end. The deep hole is honed on a vertical honing machine using a honing head with honing strips to ensure the inner hole dimensional tolerance and obtain the blank to be processed for honing the deep hole.

[0019] S110: Fine grinding of the outer diameter: Using the honed inner hole of the blank to be machined in step S100 for honing the deep hole, the inner hole is tightened by a hydraulic mandrel clamp, and the outer diameter of the large end and the outer diameter of the small end are finely ground on an external cylindrical grinding machine to ensure that the outer diameter of the large end is coaxial with the outer diameter of the small end and the inner hole is coaxial with the outer diameter of the small end, so as to obtain the blank to be machined with finely ground outer diameter;

[0020] S120: Precision machining of both ends: The small end outer circle of the pre-ground blank with the S110 precision-ground outer circle is clamped on a double-head CNC lathe to machine the sealing ring groove of the large end outer circle, as well as the small end inner hole and the inner hole sealing ring groove, to obtain a precision deep hole part.

[0021] In a preferred embodiment of the present invention, in step S40, in order to control the machining quality of the gun drill hole and avoid poor straightness affecting subsequent machining positioning, a measuring bar is used for detection. The diameter of the measuring bar is controlled to be 0.02 to 0.03 mm smaller than the measured value of the actual machined hole diameter, based on the subsequent honing allowance of 0.08 to 0.1 mm.

[0022] In a preferred embodiment of the present invention, in step S70, the expansion sleeve clamp uses a threaded tapered expansion sleeve and an unthreaded tapered expansion sleeve to tighten the middle hole of the stress-relieved blank to be processed in step S60 by screwing a large end cap and a small end cap onto the two tapered surfaces of the mandrel.

[0023] In a preferred embodiment of the present invention, for ease of assembly and disassembly, the threaded tapered expansion sleeve is pulled out by the rotation of the threads on the tightening cap nut and the threaded tapered expansion sleeve.

[0024] In a preferred embodiment of the present invention, in step S100, the honing head is connected to the main shaft of the equipment via a honing rod, and the honing rod is equipped with a honing strip and is connected by two ball joints on a connecting rod to ensure that the main shaft of the equipment and the honing rod are always in the vertical direction.

[0025] In a preferred embodiment of the present invention, in step S110, the hydraulic mandrel fixture uses the clamping screw at the left end of the mandrel to tighten the internal pressure oil, causing the expansion parts at both ends of the mandrel to expand and tighten the inner hole to finely grind the outer circle. Before processing, two standard rings need to be simultaneously tightened at the left and right ends of the mandrel 1. It is advisable that the runout of the outer circle of the standard ring is within 0.005 on the runout tester. The limit expansion amount of the expansion parts to tighten the inner hole is 0.04mm.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Using this process, the machined surface can meet the requirement of 0.02 to 0.03 coaxiality of the outer diameter of the deep hole on the drawing.

[0028] 2. Using a sleeve clamp for rough turning of the outer diameter can effectively correct the misalignment of the inner hole and the outer diameter after gun drilling, reducing the subsequent outer diameter grinding allowance and improving machining efficiency.

[0029] 3. This process uses a honing head (with honing strips) to hone deep holes. Compared with custom-made composite reamers or special boring tools, it can achieve better surface finish. At the same time, by changing honing rods and honing strips of different specifications, it can process deep hole parts with different hole diameters. It can be widely used in the processing of deep hole parts with such coaxiality requirements, effectively reducing tool usage costs and achieving better economic benefits. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the precision deep hole component in this invention.

[0032] Figure 2 This is a cross-sectional view of the precision deep hole component in this invention.

[0033] Figure 3 This is a schematic diagram of the expansion sleeve clamp in this invention.

[0034] Figure 4 This is a schematic diagram illustrating the honing head principle in this invention.

[0035] Figure 5 This is one of the schematic diagrams of the hydraulic mandrel in this invention.

[0036] Figure 6 This is the second schematic diagram of the hydraulic mandrel in this invention. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0038] A machining process for precision deep-hole parts includes the following steps:

[0039] S10: Cutting: Cutting cylindrical blanks into blanks of specified lengths for processing;

[0040] S20: Solution Aging: The blank to be processed in step S10 is subjected to solution aging treatment. This treatment adjusts the microstructure of the blank and controls the precipitated phases to improve its strength, hardness, and corrosion resistance. The process parameters for solution aging are as follows: Quenching 1040±10℃

[0041] *140min, tempering at 660±20℃*180min;

[0042] S30: Rough turning of outer diameter and chamfering: Chamfering is done on both ends of the blank to be processed after solution aging treatment in step S20 to obtain the blank to be processed after rough turning of outer diameter and chamfering, which is used for positioning of gun drill in subsequent process.

[0043] S40: Gun drilling the center hole: The blank to be machined after rough turning the outer diameter and chamfering in step S30 is gun drilled to obtain the blank to be machined after gun drilling the center hole; according to the finished size of the deep hole part, leave a machining allowance of 0.08~0.1mm on the outer surface for subsequent machining; in step S40, in order to control the machining quality of the gun drilling center hole and avoid the straightness being too poor and affecting the positioning of subsequent machining, a measuring bar is used for inspection. The diameter of the measuring bar is controlled to be 0.02~0.03mm smaller than the measured value of the actual machined hole diameter, according to the subsequent honing allowance of 0.08~0.1mm.

[0044] S50: Rough turning of the shape: The blank to be processed after the gun drilling of the middle hole in step S40 is efficiently removed from the outer surface of the blank to be processed to obtain the blank to be processed with the removed material.

[0045] S60: Stress relief aging: Remove the processing stress generated by the rough machining of the blank in step S50 to obtain a stress-relieved blank. The specific process parameters of the stress relief aging are as follows: temperature 500℃, time: 180 minutes.

[0046] S70: Rough turning of the outer circle: See also Figure 3 Position the center hole of the stress-relief blank to be machined by gun drilling in step S60, and use an expansion sleeve clamp to tighten the center hole. On a CNC lathe, use self-centering jaws to clamp the outer diameter of the large end of the stress-relief blank to be machined and rough machine the outer diameter of the small end. Leave a machining allowance of 0.1 to 0.15 mm on the outer diameter of the small end for subsequent machining, and obtain the blank to be machined with the outer diameter rough machined. The expansion sleeve clamp uses a threaded tapered expansion sleeve 2 and a non-threaded tapered expansion sleeve 5 to tighten the center hole of the stress-relief blank to be machined in step S60 by screwing the large end tightening cap 4 and the small end tightening cap 3 onto the two tapered surfaces. In order to facilitate assembly and disassembly, the threaded tapered expansion sleeve 2 is pulled out by the rotation of the threads on the tightening cap nut 6 and the threaded tapered expansion sleeve 3.

[0047] S80: Semi-finish turning of the small end: The small end of the blank to be machined, which is held by the rough turning of the outer circle in step S70, is machined on a CNC lathe to obtain a blank to be machined with a small end relief groove. The relief groove is machined to avoid tool collision in subsequent machining.

[0048] S90: Semi-finish turning of the large end: The outer diameter of the small end of the blank to be machined is machined by CNC turning of the outer diameter of the large end, and the outer diameter of the large end is obtained. A machining allowance of 0.1 to 0.15 mm is left for subsequent machining of the outer diameter of the large end.

[0049] S100: Honing the inner bore: See Figure 4 The outer circle of the small end of the blank to be machined in step S90 is held by a spring clip and axially positioned by the shoulder surface of the large end. The deep hole is honed on a vertical honing machine using a honing head with honing strips to ensure the inner hole dimensional tolerance, thus obtaining the blank to be machined for honing the deep hole. The honing head 10 is connected to the main shaft of the equipment through the honing rod 30. The honing rod 30 has honing strips and is connected by two ball joints on the connecting rod 20 to ensure that the main shaft of the equipment and the honing rod are always in the vertical direction.

[0050] S110: Fine-ground outer diameter: See [link] Figure 5 and Figure 6 The honed inner hole of the blank to be machined in step S100 is positioned, and the inner hole is tightened by a hydraulic mandrel clamp. The outer diameter of the large end and the outer diameter of the small end are precision ground on an external cylindrical grinding machine to ensure that the outer diameter of the large end and the outer diameter of the small end are coaxial and that the inner hole is coaxial with the outer diameter of the small end, thus obtaining the blank to be machined with a finely ground outer diameter. The hydraulic mandrel clamp is tightened by the clamping screw 50 at the left end of the mandrel 40 to squeeze the internal pressure oil, so that the expansion parts at both ends of the mandrel 40 expand and tighten the inner hole to finely grind the outer diameter. Before machining, two standard rings 60 need to be tightened at both ends of the mandrel 40 at the same time. The runout of the outer diameter of the standard rings 60 should be within 0.005 on the runout meter. The limit expansion amount of the expansion parts to tighten the inner hole is 0.04mm.

[0051] S120: Finishing both ends: The pre-ground small end outer circle of the blank to be machined, with the S110 precision-ground outer circle held on a double-headed CNC lathe, is machined to produce the large end outer circle sealing ring groove, the small end inner hole, and the inner hole sealing ring groove, resulting in a precision deep hole part 70 (see...). Figure 1 and Figure 2 ).

Claims

1. A machining process for precision deep-hole parts, characterized in that, Includes the following steps: S10: Cutting: Cutting cylindrical blanks into blanks of specified lengths for processing; S20: Solution aging: The blank to be processed in step S10 is subjected to solution aging treatment. The solution aging treatment is used to adjust the microstructure of the blank and control the precipitates to improve the strength, hardness and corrosion resistance of the blank. The process parameters for solution aging are as follows: quenching 1040±10℃*140min, tempering 660±20℃*180min. S30: Rough turning of outer diameter and chamfering: Chamfering is done on both ends of the blank to be processed after solution aging treatment in step S20 to obtain the blank to be processed after rough turning of outer diameter and chamfering, which is used for positioning of gun drill in subsequent process. S40: Gun drilling the center hole: Gun drilling the center hole of the blank to be processed after rough turning the outer circle and chamfering in step S30, to obtain the blank to be processed after gun drilling the center hole; according to the finished size of the deep hole part, leave a machining allowance of 0.08~0.1mm on the outer surface for subsequent processing. S50: Rough turning of the shape: The blank to be processed after the gun drilling of the middle hole in step S40 is efficiently removed from the outer surface of the blank to be processed to obtain the blank to be processed with the removed material. S60: Stress relief aging: Remove the processing stress generated by the rough machining of the blank in step S50 to obtain a stress-relieved blank. The specific process parameters of the stress relief aging are as follows: temperature 500℃, time: 180 minutes. S70: Rough turning of the outer diameter: Position the center hole of the stress-relieved blank to be machined by the gun drill in step S60, tighten the center hole with the expansion sleeve clamp, and use the self-centering jaws to clamp the large end outer diameter of the stress-relieved blank to be machined on the CNC lathe to rough turn the small end outer diameter. Leave a machining allowance of 0.1 to 0.15 mm on the small end outer diameter for subsequent machining, and obtain the blank to be machined with rough turned outer diameter; S80: Semi-finish turning of the small end: The small end of the blank to be machined, which is held by the rough turning of the outer circle in step S70, is machined on a CNC lathe to obtain a blank to be machined with a small end relief groove. The relief groove is machined to avoid tool collision in subsequent machining. S90: Semi-finish turning of the large end: The outer diameter of the small end of the blank to be machined is machined by CNC turning of the outer diameter of the large end, and the outer diameter of the large end is obtained. A machining allowance of 0.1 to 0.15 mm is left for subsequent machining of the outer diameter of the large end. S100: Honing the inner hole: The outer circle of the small end of the blank to be processed in step 90 is held by a spring clip and axially positioned by the shoulder surface of the large end. The deep hole is honed on a vertical honing machine using a honing head with honing strips to ensure the inner hole dimensional tolerance and obtain the blank to be processed for honing the deep hole. S110: Fine grinding of the outer diameter: Using the honed inner hole of the blank to be machined in step S100 for honing the deep hole, the inner hole is tightened by a hydraulic mandrel clamp, and the outer diameter of the large end and the outer diameter of the small end are finely ground on an external cylindrical grinding machine to ensure that the outer diameter of the large end is coaxial with the outer diameter of the small end and the inner hole is coaxial with the outer diameter of the small end, so as to obtain the blank to be machined with finely ground outer diameter; S120: Precision machining of both ends: The small end outer circle of the pre-ground blank with the S110 precision-ground outer circle is clamped on a double-head CNC lathe to machine the sealing ring groove of the large end outer circle, as well as the small end inner hole and the inner hole sealing ring groove, to obtain a precision deep hole part.

2. The machining process for a precision deep-hole part according to claim 1, characterized in that, In step S40, in order to control the machining quality of the gun drill hole and avoid poor straightness affecting the subsequent machining positioning, a measuring bar is used for inspection. The diameter of the measuring bar is controlled to be 0.02 to 0.03 mm smaller than the actual machined hole diameter measurement value, based on the subsequent honing allowance of 0.08 to 0.1 mm.

3. The machining process for a precision deep hole part according to claim 1, characterized in that, In step S70, the expansion sleeve clamp uses a threaded tapered expansion sleeve and an unthreaded tapered expansion sleeve, which are tightened on the two tapered surfaces of the mandrel by a large end cap and a small end cap, to tighten the middle hole of the stress-relieved blank to be processed in step S60.

4. The machining process for a precision deep hole part according to claim 3, characterized in that, To facilitate assembly and disassembly, the threaded tapered expansion sleeve is pulled out by the rotation of the threads on the tightening cap nut and the threaded tapered expansion sleeve.

5. The machining process for a precision deep-hole part according to claim 1, characterized in that, In step S100, the honing head is connected to the main shaft of the equipment via a honing rod. The honing rod has a honing strip and is connected by two ball joints on a connecting rod to ensure that the main shaft of the equipment and the honing rod are always in the vertical direction.

6. The machining process for a precision deep-hole part according to claim 1, characterized in that, In step S110, the hydraulic mandrel fixture uses the clamping screw at the left end of the mandrel to tighten the internal pressure oil, causing the expansion parts at both ends of the mandrel to expand and tighten the inner hole to finely grind the outer circle. Before processing, two standard rings need to be simultaneously tightened at the left and right ends of the mandrel 1. The runout of the outer circle of the standard rings should be within 0.005 when tested on the runout meter. The limit expansion amount of the expansion parts to tighten the inner hole is 0.04mm.

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