Machining method for inner hole symmetrical double key grooves

Abstract

The invention relates to the field of key groove machining, and discloses an inner hole symmetrical double key groove machining method which comprises the following steps that a workpiece is fixed, and the center of an inner hole of the workpiece is aligned with the center of a main shaft of a milling machine; the Y-direction coordinate is kept unchanged, the blade is controlled to move in the X + direction and make contact with an inner hole of the workpiece, X0 is set when the blade makes contact with the workpiece just now, then the blade is controlled to move in the Z direction, and Z0 is set when the blade makes contact with the workpiece; the machining tool is controlled to move to the Y0 position, and the blade on the other side is controlled to move in the X-direction and make contact with the inner hole of the workpiece to be set to be X1; the machining tool is controlled to keep the Y0 coordinate unchanged and conduct cutting in the X + direction till machining of the first key groove is completed; the machining tool is moved to the positions of X1, Y0 and Z0, the machining tool is controlled to keep the coordinate of Y0 unchanged, and cutting is conducted in the X-direction till machining of the second key groove is completed; the Y0 coordinate is locked, the reference positions of the blades on the two sides are determined through two times of tool setting, and it is ensured that the double blades are symmetrically distributed about the center of the inner hole of the workpiece.

Description

Technical Field

[0001] This invention relates to the field of keyway machining, and more specifically to a method for machining symmetrical double keyways with internal holes. Background Technology

[0002] In centrifugal pumps, double keyways are often used to increase torque and connection stability in various components such as impellers and bushings, with a required symmetry of less than 0.03 mm. Keyway symmetry is a core requirement; the working surface of the keyway needs to be symmetrical with the axis to ensure even force distribution on both sides during assembly. Insufficient symmetry will lead to uneven force distribution between the key and keyway, causing stress concentration and affecting the reliability and lifespan of torque transmission.

[0003] Currently, the machining of symmetrical double keyways in internal holes mostly relies on part indexing and recalibration. Milling machines typically employ a single-head, two-stage machining strategy. After the first keyway is machined, the part needs to be repositioned or rotated to machine the second keyway. However, this method depends on precise positioning or the machine's rotation capability. In actual production, human error, clamping limitations, or equipment precision limitations often lead to inconsistent keyway angles or coaxiality errors, severely affecting the assembly accuracy, reliability, and machining efficiency of the parts. To address these issues, we propose a machining method for symmetrical double keyways in internal holes. Summary of the Invention

[0004] The present invention aims to provide a method for machining symmetrical double keyways in internal holes, in order to solve the problem that inconsistent keyway angles or coaxiality errors caused by human error, clamping or equipment precision limitations seriously affect the assembly accuracy, reliability and machining efficiency of parts.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for machining symmetrical double keyways in an internal hole. This machining method is matched with a machining tool, which includes a tool holder, a tool holder, and two inserts. The tool holder is located on the output shaft of a milling machine. The tool holder has a through-hole mounting groove, and the tool holder is located within the mounting groove. The end of the tool holder away from the tool holder has symmetrically formed fixing grooves, and the two inserts are respectively located within the two fixing grooves. The machining method includes the following steps: Step 1, workpiece positioning: Place the workpiece on the chuck of the milling machine, rotate the chuck to fix the workpiece, control the movement of the workpiece and align the center of the inner hole of the workpiece with the center of the milling machine spindle, and set it as Y0; Step 2, First tool setting: Keep the Y-axis unchanged, control one side of the cutting tool to move in the X+ direction and contact the inner hole of the workpiece. Set it to X0 when it just contacts the workpiece. Then control the cutting tool to move in the Z direction and contact the workpiece. Set it to Z0 when it just contacts the workpiece. Step 3, Secondary tool setting: Control the machining tool to move to the Y0 position, and keep the Y and Z coordinates unchanged. Control the other side of the cutting tool to move in the X- direction and contact the inner hole of the workpiece. Set it to X1 when it just contacts the workpiece. Step 4, Machining Settings: Set the feed rate of the machining tool for each movement along the X and Z directions; Step 5, Machining the first keyway: Move the machining tool to the X0, Y0 and Z0 positions, control the machining tool to keep the Y0 coordinate unchanged and cut along the X+ direction until the machining of the first keyway is completed; Step 6, Machining the second keyway: Move the machining tool to the X1, Y0, and Z0 positions, control the machining tool to keep the Y0 coordinate unchanged and cut along the X- direction until the machining of the second keyway is completed.

[0006] The beneficial effects of this solution are as follows: By adopting a double-head machining method, the problems of secondary positioning and error accumulation are avoided. The symmetrical head structure ensures the symmetrical accuracy of the parts, enabling the machining of symmetrical double keyways in a single clamping and positioning. This simplifies the process, shortens machining time, and significantly improves production efficiency. The center of the workpiece's inner hole is precisely aligned with the center of the milling machine spindle and the Y0 coordinate is locked. Two tool settings establish the reference positions of the two side inserts, ensuring that the two inserts are symmetrically distributed about the center of the workpiece's inner hole. This ensures that the symmetry of the machined double keyway strictly meets the high-precision requirement of a through hole within 0.03mm, completely solving the assembly difficulties caused by symmetry deviations. This ensures the smoothness of part assembly and connection stability. The tool holder can be quickly changed according to the machining keyway size, and easily worn inserts can also be replaced efficiently, reducing changeover time costs.

[0007] Preferably, as an improvement, in step four, the X-axis cutting movement amount for each cut is set to 0.02mm-0.05mm.

[0008] The beneficial effects are: the micro-feed of 0.02mm-0.05mm can effectively reduce cutting stress, avoid burrs and chipping on the inner hole and keyway edges of the parts, and ensure that the keyway dimensional tolerance and surface roughness meet the standards.

[0009] Preferably, as an improvement, the outer wall of the tool holder is symmetrically provided with through holes, and each through hole is threaded with a clamping screw, which can pass through the through hole and abut against the outer wall of the tool holder.

[0010] The beneficial effects are as follows: the symmetrically distributed through holes and clamping screws form a bidirectional uniform clamping force, which balances the force on the tool holder in the mounting groove, avoids the tool holder offset and tilting problems caused by unilateral clamping, ensures the coaxiality of the tool holder and the tool holder fixture, and thus ensures the symmetrical accuracy of the double cutter heads about the center of the workpiece inner hole. The tight contact between the clamping screw and the outer wall of the tool holder effectively limits the axial and radial displacement of the tool holder caused by cutting vibration during the machining process, ensures the stability of the tool position during the cutting process, and reduces problems such as keyway size deviation and surface roughness deviation caused by vibration.

[0011] Preferably, as an improvement, the tool holder is provided with symmetrical positioning grooves at one end near the blade, and positioning pins are provided symmetrically on the outer wall of the tool holder, the positioning pins being able to abut against the positioning grooves.

[0012] The benefits are as follows: during assembly, the tool holder can be quickly positioned by simply aligning the positioning pin with the positioning slot, without the need for complex correction and adjustment. Combined with the outer circle positioning and screw clamping design, the tool holder can be quickly changed, significantly reducing the downtime cost of specification switching.

[0013] Preferably, as an improvement, the blade includes an integrally formed fixed section and a cutting section. The fixed section is polygonal and can abut against the inner wall of the mounting groove. The cutting section can cut the workpiece.

[0014] The beneficial effects are: the polygonal fixing section forms a multi-faceted fit with the inner wall of the mounting groove, which, compared with the traditional circular fixing structure, can effectively limit the rotation and radial displacement of the blade in the mounting groove, ensuring that the installation angle of the blade cutting section is accurate and consistent.

[0015] Preferably, as an improvement, a semi-circular groove is provided at the end of the cutting section away from the tool holder fixture.

[0016] The beneficial effects are: the semi-circular groove can guide the chips to be discharged in an orderly manner, avoid the chips from wrapping around the tool or scratching the surface of the machined keyway, and ensure a continuous and smooth cutting process. Attached Figure Description

[0017] Figure 1 This is a partial cross-sectional view of the machining tool according to an embodiment of the present invention; Figure 2 This is a partial cross-sectional view of the tool holder fixture according to an embodiment of the present invention; Figure 3 This is a top view of the blade structure according to an embodiment of the present invention; Figure 4 This is a partial cross-sectional view of the blade according to an embodiment of the present invention. Detailed Implementation

[0018] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: tool holder fixture 1, threaded hole 2, output shaft 3, mounting groove 4, through hole 5, positioning groove 6, positioning pin 7, fixing groove 8, cutting tool 9, fixing section 10, cutting section 11, semi-circular groove 12, and tool holder 13.

[0019] Example The basic implementation examples are as follows: Figures 1-4 As shown, a method for machining symmetrical double keyways in an internal hole is described, which is matched with a machining tool, such as... Figure 1 The machining tool shown includes a tool holder fixture 1, a tool holder 13, and two cutting inserts 9, as follows: Figure 2 The tool holder 1 shown has several threaded holes 2 on the right side of its outer wall, such as... Figure 1 The tool holder 1 shown is fixedly connected to the output shaft 3 of the milling machine via bolts and threaded holes 2. Figure 2 The tool holder 1 shown has a mounting groove 4 extending through its axis in the middle. Symmetrical through holes 5 are formed on the front and rear outer walls of the tool holder 1, and each through hole 5 is threaded with a clamping screw. Figure 1 The upper end of the tool holder 13 is inserted into the mounting groove 4. The clamping screw can penetrate through the through hole 5 and abut against the outer wall of the tool holder 13. The lower end of the tool holder clamp 1 has symmetrically opened positioning grooves 6. The upper outer wall of the tool holder 13 is symmetrically fixedly installed with positioning pins 7, and the positioning pins 7 can abut against the corresponding positioning grooves 6. During assembly, the positioning pins 7 only need to be aligned with the positioning grooves 6 to quickly complete the circumferential positioning of the tool holder 13 without complex correction and adjustment. With the outer circle positioning and screw clamping design, the tool holder 13 can be quickly changed, significantly reducing the downtime cost of specification switching. The lower end of the tool holder 13 has symmetrically opened fixing grooves 8. The two blades 9 are fixedly installed in the two fixing grooves 8 by bolts. Figure 3 The blade 9 shown includes an integrally formed fixing section 10 and a cutting section 11. The fixing section 10 is polygonal; in this embodiment, it is trapezoidal. The fixing section 10 abuts against the inner wall of the mounting groove 4. The polygonal fixing section 10 forms a multi-faceted fit with the inner wall of the mounting groove 4. Compared to the traditional circular fixing structure, this effectively restricts the rotation and radial displacement of the blade 9 within the mounting groove 4, ensuring that the installation angle of the cutting section 11 is precise and consistent. The cutting section 11 can cut the workpiece, such as... Figure 4 The cutting section 11 shown has a semi-circular groove 12 on the upper right side. The semi-circular groove 12 can guide the chips to be discharged in an orderly manner, avoid the chips from wrapping around the tool or scratching the surface of the machined keyway, and ensure that the cutting process is continuous and smooth.

[0020] The processing method includes the following steps: Step 1, workpiece positioning: Place the workpiece on the chuck of the milling machine, rotate the chuck to fix the workpiece, control the movement of the workpiece and align the center of the inner hole of the workpiece with the center of the milling machine spindle, and set it as Y0; Step 2, First tool setting: Keep the Y-axis unchanged, control the blade 9 on one side to move in the X+ direction and contact the inner hole of the workpiece. Set it to X0 when it just contacts the workpiece. Then control the blade 9 to move in the Z direction and contact the workpiece. Set it to Z0 when it just contacts the workpiece. Step 3, Secondary tool setting: Control the machining tool to move to the Y0 position, and keep the Y and Z coordinates unchanged. Control the other side of the cutting tool 9 to move in the X- direction and contact the inner hole of the workpiece. Set it to X1 when it just contacts the workpiece. Step 4, Machining Settings: Set the feed rate of the machining tool for each movement along the X and Z axes. Set the X-axis cutting movement for each movement to 0.02mm-0.05mm. Step 5, Machining the first keyway: Move the machining tool to the X0, Y0 and Z0 positions, control the machining tool to keep the Y0 coordinate unchanged and cut along the X+ direction until the machining of the first keyway is completed; Step 6, Machining the second keyway: Move the machining tool to the X1, Y0, and Z0 positions, control the machining tool to keep the Y0 coordinate unchanged and cut along the X- direction until the machining of the second keyway is completed.

[0021] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for machining symmetrical double keyways in internal holes, characterized in that: This machining method uses a machining tool, which includes a tool holder fixture, a tool holder, and two inserts. The tool holder fixture is located on the output shaft of the milling machine and has a through-hole mounting slot. The tool holder is placed in the mounting slot, and the end of the tool holder away from the tool holder fixture has symmetrical fixing slots. The two inserts are placed in the two fixing slots respectively. The machining method includes the following steps: Step 1, workpiece positioning: Place the workpiece on the chuck of the milling machine, rotate the chuck to fix the workpiece, control the movement of the workpiece and align the center of the inner hole of the workpiece with the center of the milling machine spindle, and set it as Y0; Step 2, First tool setting: Keep the Y-axis unchanged, control one side of the cutting tool to move in the X+ direction and contact the inner hole of the workpiece. Set it to X0 when it just contacts the workpiece. Then control the cutting tool to move in the Z direction and contact the workpiece. Set it to Z0 when it just contacts the workpiece. Step 3, Secondary tool setting: Control the machining tool to move to the Y0 position, and keep the Y and Z coordinates unchanged. Control the other side of the cutting tool to move in the X- direction and contact the inner hole of the workpiece. Set it to X1 when it just contacts the workpiece. Step 4, Machining Settings: Set the feed rate of the machining tool for each movement along the X and Z directions; Step 5, Machining the first keyway: Move the machining tool to the X0, Y0 and Z0 positions, control the machining tool to keep the Y0 coordinate unchanged and cut along the X+ direction until the machining of the first keyway is completed; Step 6, Machining the second keyway: Move the machining tool to the X1, Y0, and Z0 positions, control the machining tool to keep the Y0 coordinate unchanged and cut along the X- direction until the machining of the second keyway is completed.

2. The method for machining a symmetrical double keyway in an internal hole according to claim 1, characterized in that: In step four, the X-axis cutting movement is set to 0.02mm-0.05mm for each cut.

3. The method for machining a symmetrical double keyway in an internal hole according to claim 2, characterized in that: The tool holder has symmetrical through holes on its outer wall, and each through hole is threaded with a clamping screw. The clamping screw can pass through the through hole and abut against the outer wall of the tool holder.

4. The method for machining a symmetrical double keyway in an internal hole according to claim 3, characterized in that: The tool holder has symmetrically arranged positioning grooves at one end near the blade, and symmetrically arranged positioning pins on the outer wall of the tool holder, which can abut against the positioning grooves.

5. The method for machining a symmetrical double keyway in an internal hole according to claim 4, characterized in that: The blade consists of a fixed section and a cutting section formed in one piece. The fixed section is polygonal and can abut against the inner wall of the mounting groove. The cutting section can cut the workpiece.

6. The method for machining a symmetrical double keyway in an internal hole according to claim 5, characterized in that: A semi-circular groove is provided at the end of the cutting section away from the tool holder fixture.

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