Large-size deep blind hole shell processing method

Abstract

The application relates to the technical field of machining, and discloses a large-size deep blind hole shell machining method, which comprises the following steps: rough machining of a stepped hole in a blank hole, and then rough machining of a shell cavity; installing a tool bar on a numerical control machine tool and sleeving a flexible tool bar supporting piece on the outer wall of the tool bar, then removing machining allowance of a hole bottom taper section part of the shell cavity by a hole arranging method to form multiple steps with different diameters in the taper section of the shell cavity, and then semi-finishing the hole bottom taper section part of the shell cavity by a numerical control interpolation method; rough machining of an outer circle of the shell; finishing the shell cavity, and then finishing the outer shape surface of the shell; in the finishing stage, two processes are used to machine the hole bottom taper section part, the machining difficulty is reduced, and the machining precision is improved.

Description

Technical Field

[0001] This invention relates to the field of machining technology, and in particular to a method for machining large-size deep blind hole shells. Background Technology

[0002] The large-sized, thick-walled, deep blind hole shell made of high-strength and high-toughness metal material is a key component of a large metal assembly structure. Its head is designed as a conical structure to enhance the structure's penetration stability. However, its large internal depth and the fact that some sections of the internal cavity are spatially curved surfaces with rotating cross-sections necessitate high machining precision, making its processing difficult. Furthermore, the material blank for this large-sized, thick-walled, deep blind hole shell requires high tensile strength and impact toughness after heat treatment, further increasing the difficulty of machining. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a method for processing large-size deep blind hole shells, thereby solving the technical problem that large-size deep blind hole shells are difficult to process in the prior art.

[0004] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: This invention provides a method for machining large-size deep blind hole shells, comprising the following steps: S1. Perform step-hole roughing on the inner hole of the blank, and then perform roughing on the shell cavity; S2. Install a tool holder on a CNC machine tool and fit a flexible tool holder support on the outer wall of the tool holder. Then, use the hole-drilling method to remove the machining allowance of the bottom conical section of the housing cavity to form a multi-stage step with different diameters in the conical section of the housing cavity. Then, use the CNC interpolation method to perform semi-finishing on the bottom conical section of the housing cavity. S3. Perform rough machining on the outer diameter of the shell; S4. Perform precision machining on the shell cavity, and then perform precision machining on the outer surface of the shell.

[0005] Preferably, the rough machining of the outer circle of the shell uses the inner hole after the semi-finishing of the shell cavity as the machining reference.

[0006] Preferably, the tool holder has a cavity inside, and the inner diameter of the cavity gradually decreases in the direction toward which the tool head is mounted on the tool holder; a cooling pipe is provided inside the cavity, and a nozzle is provided at the end of the tool holder.

[0007] Preferably, the CNC machine tool has a detachable tool holder fixing seat on its middle support plate, and the end of the tool holder away from the tool head is fixed to the tool holder fixing seat.

[0008] Preferably, the outer wall of the tool holder support is fitted with a small clearance to the inner hole of the semi-finished housing cavity; the tool holder support includes a flexible body and a rigid pad, the flexible pad is sleeved on the outer wall of the tool holder, and the rigid pad is embedded in the outer wall of the flexible body.

[0009] Preferably, a sliding sleeve is provided on the outer wall of the tool holder, and the sliding sleeve is supported in the inner hole of the shell cavity that has been semi-finished; the sliding sleeve is provided with a groove that runs through the sliding sleeve along the length of the tool holder.

[0010] Preferably, the precision machining of the housing cavity includes the following steps: Perform the machining benchmark process; The inner holes of the shell cavity are machined sequentially from the outside to the inside, and the internal threads of the shell cavity are precision machined; the tapered section at the bottom of the hole of the shell cavity is machined using CNC interpolation.

[0011] Preferably, during the machining of the internal threads of the housing cavity, a tenon support is fixedly provided at the end of the tool holder away from the tool head; a tenon is fixedly connected at the end of the tenon support away from the tool holder, and the other end of the tenon is fixedly connected to the tool holder fixing seat.

[0012] Preferably, the finishing of the outer surface of the housing includes the following steps: First, use the main chuck of the CNC machine tool to clamp and fix the outer circle of the housing head, and use the chuck of the tailstock of the CNC machine tool to support the inner hole of the housing cavity; Then the outer circle and external threads of the car body; The housing is disassembled and its orientation is adjusted. Then, the main chuck uses a jig to clamp the threaded outer circle of the housing and supports the housing with a center frame. Finally, the outer circle process chuck of the housing head is machined.

[0013] Preferably, the diameter of adjacent steps in S2 differs by 2.5 mm.

[0014] Compared with the prior art, the large-size deep blind hole shell processing method provided in this embodiment of the invention has the following advantages: In this invention, to address the problem of the high machining difficulty of the inner cavity of the housing, during the semi-finishing stage of the housing cavity, a hole-drilling method is first used to remove most of the machining allowance, and different steps are machined to approximately form the contour of the required bottom conical section of the hole, reducing the difficulty of subsequent machining. Then, a CNC interpolation machining method is used to further semi-finish the bottom conical section of the housing cavity, so that the bottom conical section of the housing cavity initially reaches the required outer contour, reducing the cutting difficulty of the inner cavity of the housing. At the same time, the segmented machining also improves the machining accuracy of the housing cavity. Attached Figure Description

[0015] Figure 1This is a flowchart illustrating the present invention; Figure 2 This is a schematic diagram of the structure of the blank inner hole after rough machining of the stepped hole according to the present invention; Figure 3 This is a schematic diagram of the shell cavity after rough machining according to the present invention; Figure 4 This is a schematic diagram of the structure of the bottom conical section of the hole of the present invention after the step is machined. Figure 5 This is a simplified structural diagram of the processing state of the present invention; Figure 6 This is another simplified structural diagram of the processing state of the present invention; Figure 7 This is a schematic diagram of the tool holder structure of the present invention; Figure 8 This is a schematic diagram of the structure of the tool holder support component of the present invention; Figure 9 This is a schematic diagram of the sliding sleeve of the present invention; Figure 10 This is a structural schematic diagram of the tenon and groove support member of the present invention; Figure 11 This is a schematic diagram of the finished product structure of the present invention.

[0016] In the diagram: 1. Shell; 11. Conical section at the bottom of the hole; 12. Step 2. Tool holder; 21. Cavity; 22. Cooling pipe; 3. Tool holder fixing seat; 4. Tool holder support; 41. Flexible body; 42. Rigid pad; 5. Sliding sleeve; 51. Slide groove; 6. Mortise and tenon support; 61. Tenon. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] To address the technical difficulties in machining existing shells due to their large internal cavity depth, high machining accuracy requirements, and challenging cutting processes, this invention provides a method for machining large-size deep blind hole shells. This method involves machining the bottom conical section of the shell cavity twice, which reduces machining difficulty while ensuring machining accuracy.

[0019] like Figures 1 to 11 As shown, a preferred embodiment of the present invention provides a method for processing a large-size deep blind hole shell, which includes the following steps: S1. Rough machining of the inner hole of the blank with 12 steps, and then rough machining of the cavity of shell 1; S2. Install the tool holder 2 on the CNC machine tool and fit a flexible tool holder support 4 on the outer wall of the tool holder 2. Then, use the hole-drilling method to remove the machining allowance of the bottom conical section 11 of the cavity of the housing 1 to form a multi-stage step 12 with different diameters in the conical section of the cavity of the housing 1. Then, use the CNC interpolation method to perform semi-finishing on the bottom conical section 11 of the cavity of the housing 1. S3. Perform rough machining on the outer diameter of shell 1; S4. Perform precision machining on the cavity of shell 1, and then perform precision machining on the outer surface of shell 1.

[0020] Specifically, in this embodiment, the inner hole of the raw material bar billet first needs to be rough machined with T-shaped stepped 12 holes. This process requires machining multiple stepped 12 holes in the inner hole of the billet as needed. This machining process is preferably carried out using a deep hole drilling and boring machine, a professional deep hole machining equipment, which can complete the rough machining of the stepped 12 holes more quickly and stably. Then, the cavity of the shell 1 is rough machined using an ordinary horizontal lathe. During this process, a special extended countersinking machine is used to machine the bottom of the cavity of the shell 1 into an arc-shaped surface, which facilitates the subsequent semi-finishing of the cavity of the shell 1.

[0021] Then, a dedicated tool holder 2 is installed on a CNC machine tool to perform semi-finishing on the cavity of housing 1. A flexible tool holder support 4 is fitted onto the outer wall of the tool holder 2. The outer side of the tool holder support 4 abuts against the cavity of housing 1. Its flexible structure can effectively absorb the vibration and impact of the tool holder 2, thereby controlling the elasticity of the tool holder 2 and vibration during the machining process, thus improving the machining accuracy and stability of the tool tip at the end of the tool holder 2, and meeting the needs of subsequent CNC interpolation machining. After the tool holder 2 and the tool holder support 4 are installed, semi-finishing of the cavity of housing 1 can begin. Since the tensile strength and impact toughness requirements of the housing 1 blank are high after heat treatment, the cutting process is relatively difficult. Therefore, this embodiment adjusts the machining process of the cavity of housing 1. The main body of the cavity of housing 1 can be semi-finished normally as required. However, the bottom cone section 11 at the deepest part of the cavity of housing 1 is the most difficult to machine, so it is machined in two sections. For the bottom conical section 11, a hole-drilling method is first used to remove most of the machining allowance during the rough machining stage of the housing 1 cavity, reducing the cutting allowance for subsequent machining and lowering the machining difficulty of subsequent machining processes. Simultaneously, multiple steps 12 of different diameters are machined into the bottom conical section 11 to approximate the required contour of the bottom conical section 11, facilitating subsequent CNC interpolation machining and reducing its difficulty. Then, CNC interpolation is used to perform semi-finishing of the bottom conical section 11, forming the required contour for subsequent finishing processes. In one specific embodiment, the bottom conical section 11 is machined with forty steps 12, with a diameter difference of 2.5 mm between adjacent steps 12. In other embodiments, the number of steps 12 and the diameter difference between adjacent steps 12 can be adjusted according to the required contour dimensions of the bottom conical section 11 and the machining accuracy control requirements.

[0022] It is understandable that after the semi-finishing of the cavity of housing 1, a machining allowance needs to be left for the subsequent finishing process. In a specific embodiment, after the semi-finishing of the cavity of housing 1, a finishing allowance of 2.5 mm needs to be left on one side to facilitate the subsequent finishing process.

[0023] In some embodiments, the rough machining of the outer circle of the housing 1 uses the inner hole after the semi-finishing of the cavity of the housing 1 as the machining reference.

[0024] Specifically, before semi-finishing the cavity of housing 1, it is necessary to first machine and align the reference, and then perform semi-finishing of the cavity of housing 1. Subsequently, during roughing of the outer circle of housing 1, the inner hole of the cavity of housing 1 after semi-finishing is used as the machining reference, thereby ensuring that the inner hole of the cavity of housing 1 and the outer circle of housing 1 remain coaxial.

[0025] In some embodiments, the tool holder 2 has a cavity 21 inside, and the inner diameter of the cavity 21 gradually decreases in the direction toward which the tool head is mounted on the tool holder 2; a cooling pipe 22 is provided inside the cavity 21, and a nozzle is provided at the end of the tool holder 2.

[0026] Specifically, the tool holder 2 is preferably made of a material with high rigidity, and a cavity 21 is provided inside it to reduce the weight of the tool holder 2. The cavity 21 also facilitates the passage of the cooling pipe 22. The cooling pipe 22 and the nozzle (not shown in the figure) are arranged to deliver and spray coolant during the machining process to achieve cooling and chip removal.

[0027] In some embodiments, the middle support plate of the CNC machine tool is detachably provided with a tool holder fixing seat 3, and the end of the tool holder 2 away from the tool head is fixed to the tool holder fixing seat 3.

[0028] Specifically, in this embodiment, a tool holder fixing seat 3 is detachably installed on the middle support plate of the CNC machine tool. Then, the tool center height of the tool holder fixing seat 3 is adjusted to coincide with the tool center height of the CNC lathe. Subsequently, the aforementioned tool holder 2 is fixedly installed on the tool holder fixing seat 3 to facilitate subsequent semi-finishing and finishing of the cavity of the housing 1. Compared to the traditional machining solution of directly fixing the tool holder 2 to the rotary turret of the CNC machine tool, this approach avoids altering the rotary turret of the CNC lathe, preventing potential equipment hazards. Furthermore, the tool holder fixing seat 3 can be easily disassembled and installed, offering greater flexibility and minimizing impact on normal machine operation.

[0029] In some embodiments, the outer wall of the tool holder support 4 is fitted with a small clearance to the inner hole of the housing 1 cavity that has been semi-finished; the tool holder support 4 includes a flexible body 41 and a rigid pad 42, the flexible pad is sleeved on the outer wall of the tool holder 2, and the rigid pad 42 is embedded in the outer wall of the flexible body 41.

[0030] Specifically, the tool holder support 4 is installed at an appropriate position along the outer axial direction of the tool holder 2 according to actual usage requirements. It uses a flexible medium as its body, with the flexible body 41 sleeved on the outer wall of the tool holder 2. This absorbs and dissipates the vibration and impact of the tool holder 2 during machining, thereby controlling the elasticity and vibration of the tool holder 2 during machining. This improves the stability of the tool tip at the end of the tool holder 2 during machining, increases machining accuracy, and facilitates the smooth execution of CNC interpolation processes during semi-finishing and finishing. The rigid pad 42 is embedded in the outer wall of the flexible body 41, abutting against the inner wall of the cavity of the housing 1, thus increasing the wear resistance of the tool holder support 4. It is understood that in some embodiments, multiple tool holder supports 4 may be spaced apart along the length of the tool holder 2.

[0031] In some embodiments, a sliding sleeve 5 is provided on the outer wall of the tool holder 2, and the sliding sleeve 5 is supported in the cavity of the housing 1 that has been semi-finished; the sliding sleeve 5 is provided with a groove 51 that runs through the sliding sleeve 5 along the length of the tool holder 2.

[0032] Specifically, during the semi-finishing and finishing of the cavity of housing 1 using CNC interpolation, a sliding sleeve 5 is additionally provided to meet the requirement of free sliding interpolation of the tool holder 2 along the feed direction. This sliding sleeve 5 is supported in a semi-finished inner hole within the cavity of housing 1 and has a groove 51 on it. The tool holder 2 is positioned within this groove 51. This sliding sleeve 5 ensures that the tool holder 2 can freely slide and interpolate along the feed direction while further preventing severe vibration of the tool holder 2 during machining. It is understood that in some embodiments, multiple sliding sleeves 5 may be spaced apart along the length of the tool holder 2.

[0033] In some embodiments, the finishing of the cavity of housing 1 includes the following steps: Perform the machining benchmark process; The inner hole of the housing 1 cavity is machined sequentially from the outside to the inside, and the internal thread of the housing 1 cavity is precision machined; the bottom cone section 11 of the housing 1 cavity is machined by CNC interpolation.

[0034] Specifically, before finishing the cavity of housing 1, a reference machining process is also required. This mainly involves machining the rear end face of housing 1 away from the bottom cone section 11 and the outer cylindrical sections at both ends of housing 1, serving as a support reference for the alignment belt and the lathe center rest. Subsequently, the inner hole of housing 1 is finished from the outside to the inside, and the bottom cone section 11 is finished using CNC interpolation. The sliding sleeve 5 and the tool holder support 4 ensure that the tool holder 2 can freely slide and interpolate in the feed direction, while also preventing severe vibration and elastic tool deflection during the machining process, thus improving the machining accuracy of the tool head to meet the requirements of CNC interpolation.

[0035] In some embodiments, when machining the internal thread of the housing 1 cavity, a tenon support 6 is fixedly provided at the end of the tool holder 2 away from the tool head; a tenon 61 is fixedly connected at the end of the tenon support 6 away from the tool holder 2, and the other end of the tenon 61 is fixedly connected to the tool holder fixing seat 3.

[0036] Specifically, in this embodiment, the internal threads of the housing 1 cavity also need to be precision machined. These internal threads must be machined according to a CNC program. Since the machine tool cannot apply constraints in the X and Z axes, this embodiment includes a tenon support 6 and a tenon 61. The tenon support 6 has a groove, one end of the tenon 61 is placed in the groove, and the other end is placed in the slot of the tool holder fixing seat, and is fixedly connected to the tool holder fixing seat by bolts. The cooperation between the tenon support 6 and the tenon 61 further increases the rigidity of the tool holder 2, thereby preventing vibration of the tool holder 2 and ensuring the stability and reliability of the internal thread machining accuracy and quality.

[0037] In some embodiments, the finishing of the outer surface of the housing 1 includes the following steps: First, use the main chuck of the CNC machine tool to clamp and fix the outer circle of the head of the housing 1, and use the chuck of the tailstock of the CNC machine tool to support the inner hole of the cavity of the housing 1; Then the outer circle and external threads of the car body 1; Disassemble housing 1 and adjust its orientation. Then, the main chuck uses a jig to clamp the threaded outer circle of housing 1 and supports housing 1 with a center frame. Then, machine the outer circle process chuck at the head of housing 1.

[0038] Specifically, after the cavity of housing 1 is finished, the finishing of the outer surface of housing 1 can begin. First, the outer diameter of the head (conical part) of housing 1 is clamped by the four jaws of the main chuck of the CNC machine tool, and the inner hole of the cavity of housing 1 is supported by the four jaws of the tailstock. Then, the outer diameter and external thread of housing 1 can be machined. The external thread is located at the tail of housing 1. Then, housing 1 is turned around, and the threaded outer diameter is clamped by the four jaws of the main chuck using a fixture. The main body of housing 1 is supported by the center rest. Then, the outer diameter of the head of housing 1 is machined by the process chuck, and finally the machining of housing 1 is completed.

[0039] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for machining large-size deep blind hole shells, characterized in that, Includes the following steps: S1. Perform step-hole roughing on the inner hole of the blank, and then perform roughing on the shell cavity; S2. Install a tool holder on a CNC machine tool and fit a flexible tool holder support on the outer wall of the tool holder. Then, use the hole-drilling method to remove the machining allowance of the bottom conical section of the housing cavity to form a multi-stage step with different diameters in the conical section of the housing cavity. Then, use the CNC interpolation method to perform semi-finishing on the bottom conical section of the housing cavity. S3. Perform rough machining on the outer diameter of the shell; S4. Perform precision machining on the shell cavity, and then perform precision machining on the outer surface of the shell.

2. The method for processing large-size deep blind hole shells according to claim 1, characterized in that, The rough machining of the outer diameter of the shell is based on the inner hole after the semi-finishing of the shell cavity.

3. The method for processing large-size deep blind hole shells according to claim 1, characterized in that, The tool holder has a cavity inside, and the inner diameter of the cavity gradually decreases in the direction toward which the tool head is mounted on the tool holder; a cooling pipe is provided inside the cavity, and a nozzle is provided at the end of the tool holder.

4. The method for processing large-size deep blind hole shells according to claim 3, characterized in that, The CNC machine tool has a detachable tool holder fixing seat on its middle support plate, and the end of the tool holder away from the tool head is fixed to the tool holder fixing seat.

5. The method for processing large-size deep blind hole shells according to claim 4, characterized in that, The outer wall of the tool holder support is fitted with a small clearance to the inner hole of the semi-finished housing cavity; the tool holder support includes a flexible body and a rigid pad, the flexible pad is sleeved on the outer wall of the tool holder, and the rigid pad is embedded in the outer wall of the flexible body.

6. The method for processing large-size deep blind hole shells according to claim 5, characterized in that, The outer wall of the tool holder is fitted with a sliding sleeve, which is supported in the inner hole of the shell cavity that has been semi-finished; the sliding sleeve is provided with a groove that runs through the sliding sleeve along the length of the tool holder.

7. The method for processing large-size deep blind hole shells according to claim 6, characterized in that, The finishing process of the shell cavity includes the following steps: Perform the machining reference process; The inner holes of the shell cavity are machined sequentially from the outside to the inside, and the internal threads of the shell cavity are precision machined; the tapered section at the bottom of the hole of the shell cavity is machined using CNC interpolation.

8. The method for processing large-size deep blind hole shells according to claim 7, characterized in that, When machining the internal threads of the housing cavity, a tenon support is fixedly provided at the end of the tool holder away from the tool head; a tenon is fixedly connected at the end of the tenon support away from the tool holder, and the other end of the tenon is fixedly connected to the tool holder fixing seat.

9. The method for machining large-size deep blind hole shells according to claim 1, characterized in that, The finishing process for the outer surface of the housing includes the following steps: First, use the main chuck of the CNC machine tool to clamp and fix the outer circle of the housing head, and use the chuck of the tailstock of the CNC machine tool to support the inner hole of the housing cavity; Then the outer circle and external threads of the car body; The housing is disassembled and its orientation is adjusted. Then, the main chuck uses a jig to clamp the threaded outer circle of the housing and supports the housing with a center frame. Finally, the outer circle process chuck of the housing head is machined.

10. The method for processing large-size deep blind hole shells according to claim 1, characterized in that, The diameter of adjacent steps in S2 differs by 2.5 mm.

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