Numerical control milling method for square cambered pocket of retainer

Abstract

This invention proposes a CNC milling method for machining the square arc-shaped pocket of a cage, comprising steps S1-S13. Step S1 involves selecting the machine tool and cutting tools; the machine tool is a five-axis vertical machining center, and the cutting tools are large-diameter end mills, small-diameter end mills, large-diameter ball end mills, and small-diameter ball end mills. Steps S2 and S3 involve workpiece positioning and interference elimination measurements. The remaining steps S4-S13 involve workpiece deflection and milling with different cutting tools, respectively. Using this method, no forming cutter is required; the machining of the inner wall of the square arc-shaped pocket of the cage can be achieved using a standard ball end mill, reducing the ordering of forming cutters and enabling the machining of inverted half-shaped ball-shaped pocket structures of the same type but different sizes using standard end mills.

Description

Technical Field

[0001] The present invention relates to bearing manufacturing technology, especially to the processing technology of bearing cages, and specifically to a numerical control milling method for the square arc-shaped pocket holes of cages. Background Art

[0002] The material of a certain type of cage of a traction motor bearing is aluminum bronze, and its structure is as Figure 1 shown. A number of square pocket holes are evenly distributed along the circumferential direction of the outer diameter surface of the cage. The inner walls of both sides of the pocket hole close to the end face are flush with the end face. The structures of the other two side walls of the pocket hole are the combination surfaces of a section of cylindrical surface and a plane. The opening size of the outer diameter surface of the pocket hole is small, and the opening size of the inner diameter surface is large. The whole structure is an inverted semi-spherical pocket, and empty knife grooves are provided at the four corners.

[0003] To improve the processing efficiency, the pocket hole forming of the above cage is currently processed by a forming tool. The ideal shape of this tool is shown in Figure 3 . When using the tool as shown in Figure 3 , by analyzing the product structure, it is necessary to ensure no interference during processing first. The axial diagram of a single pocket hole is shown in Figure 2 . The customized non-standard tool must ensure that the processing dimensions in the length direction of the pocket hole completely cover the entire pocket hole. During actual processing, the cutting length of the tool should be greater than the wall thickness of the cage.

[0004] When the tool shape is made into the combined shape of the arc surface and the plane of the pocket holes along the circumferential direction, through simulation, when the tool is made into the shape of Figure 3 , if the tool diameter d > E, at this time, except that the middle part is processed to meet the drawing requirements, there will be unprocessed situations on the inner walls of the four combined surfaces near the empty knife grooves (see Figure 4 ). And to solve this situation, it can only be achieved by reducing the tool diameter. First, use a large-diameter tool of the same shape to rough mill to remove large allowances, and then use a smaller-diameter tool to complete the finish milling, such as Figure 3 , Figure 4 , and when the diameter d of the forming tool < E can be completely removed (because if the tool diameter d = E, due to the impact during cutting, there are unstable factors in the actual path of the tool, and it is extremely easy to exceed the tolerance); at this time, because the diameter D of the forming part > d, since the cutting depth of the forming part is inconsistent with the part with a diameter of d, there will be an over-cut phenomenon in the thickness of the parallel plane on the inner wall of the combined surface during processing. To solve this problem, it can only be solved by at least two finish milling operations and continuously fine-tuning the cutting depth, which requires a high level of the operator. In addition, when designing the forming tool, due to the limitation of the pocket hole structure size on the tool diameter, the requirements for the tool are extremely high. Especially for the forming tool, it is difficult to grind, and it is not easy to control the change of the tool's outer dimension after grinding, resulting in a high tool grinding scrap rate and a significant increase in the tool cost.

[0005] Therefore, if conventional cutting tools can be used to process the pockets, it will certainly contribute to reducing costs and increasing efficiency for processing enterprises. Summary of the Invention

[0006] In response to the problems pointed out in the background art, the purpose of this invention is to propose a CNC milling method for the square arc-shaped pocket of a cage. This method uses a standard ball end mill to machine the inner wall of the square arc-shaped pocket of the cage, reducing the ordering of forming milling cutters and enabling the standard end mill to machine the inverted half-shaped ball pocket structure of the same type of cage but different sizes.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A CNC milling method for machining a square arc-shaped pocket on a cage includes the following steps:

[0009] Step S1, Machine tool and cutting tool selection; The machine tool selected is a five-axis vertical machining center, and the cutting tools selected are large-diameter end mills, small-diameter end mills, large-diameter ball end mills, and small-diameter ball end mills;

[0010] Step S2: Fix the cage on the A-axis so that the axis of the cage is collinear with the axis of the A-axis;

[0011] Step S3: Rotate axis A so that the axis of the uppermost pocket of the cage is parallel to the Z-axis. Set the number of the uppermost pocket as 1#. Then, number the remaining pockets in a counterclockwise direction as 2#, 3#, ..., N#, where N is the total number of pockets of the cage. In the YZ plane where the center of pocket 1# is located, set the angle between the line connecting the midpoint of the upper left side of pocket 1# to the center of pocket 1# and the horizontal plane as ∠α. Measure the angle value β of ∠α.

[0012] Step S4: Install the large-diameter end mill on the Z-axis and use the large-diameter end mill to rough mill the overall contour of the #1 pocket hole;

[0013] After rough milling the overall contour of pocket #1 in step S5, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the angle θ between the center lines of the two adjacent pockets, so that pocket #2 is in the machining position. Use a large-diameter end mill to rough mill the overall contour of pocket #2.

[0014] Step S6: Following the overall contour machining steps of hole #2, use a large-diameter end mill to rough mill the overall contours of holes #3, ..., N in sequence;

[0015] Step S7: Reset the No. 1 pocket, change the Z-axis tool to a small diameter end mill, and use the small diameter end mill to machine the empty grooves at the four corners of the No. 1 pocket;

[0016] After the empty grooves at the four corners of pocket #1 are machined in step S8, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the angle θ between the center lines of two adjacent pockets, so that pocket #2 is in the machining position. Use a small-diameter end mill to rough mill the empty grooves at the four corners of pocket #2.

[0017] Step S9: Following the machining steps for the empty grooves at the four corners of the #2 pocket, use a small-diameter end mill to machine the empty grooves at the four corners of the #3, ..., N pockets in sequence;

[0018] Step S10: Reset the No. 1 pocket, change the Z-axis tool to a large diameter ball end mill, and perform semi-finish milling on the No. 1 pocket contour;

[0019] Step S11: After the semi-finish milling of the 1# pocket contour is completed, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the included angle θ between the center lines of the two adjacent pockets, so that the 2# pocket is in the machining position. Use a large diameter ball end mill to semi-finish mill the 2# pocket contour.

[0020] Step S12: Following the semi-finish milling steps for the 2# pocket contour, use a large-diameter ball end mill to sequentially semi-finish mill the 3#, ..., N# pocket contours;

[0021] Step S13: Reset the #1 pocket, change the Z-axis tool to a small-diameter ball end mill; adjust the tool compensation parameters, and repeat steps S10 to S12 to finish mill the contours of pockets #1, #2, #3, ... N in sequence.

[0022] In step S1, the cutting tool diameters are ordered as follows: large diameter end mill > large diameter ball end mill > small diameter ball end mill > small diameter end mill.

[0023] In step S4, the method for rough milling the overall contour of the No. 1 pocket hole with a large-diameter end mill is as follows: Z-axis layer milling is adopted, the depth of cut in a single Z-axis layer does not exceed 1 mm, and the allowance for each contour layer is 0.4-0.8 mm.

[0024] In step S7, the method for machining the empty grooves at the four corners of the No. 1 pocket hole with a small-diameter end mill is as follows: Z-axis layer milling is adopted, the depth of cut in a single Z-axis layer does not exceed 0.5 mm, and no allowance is left for each layer contour.

[0025] In step S10, the semi-finish milling method for the #1 pocket is as follows: Based on the measured angle value β, rotate axis A clockwise. The rotation angle of axis A is equal to β. At this time, the #1 pocket enters the machining position. After machining one side contour of the #1 pocket, the tool is lifted, and axis A is rotated counterclockwise to rotate axis A to the mirror position. Mirror machining is used to mill the other side contour of the #1 pocket. After that, the tool is lifted, axis A is reset, and the semi-finish milling of the #1 pocket ends.

[0026] In step S11, after the 2# pocket is in the machining position, its semi-finish milling method is the same as that of the 1# pocket.

[0027] The beneficial effects of this invention are: by using a standard ball end mill to machine the inner wall of the square arc-shaped pocket of the cage, this invention reduces the ordering of forming milling cutters, enables the standard end mill to machine the inverted half-shaped ball pocket structure of the same type but different sizes of cage, reduces processing costs, and improves enterprise efficiency. Attached Figure Description

[0028] Figure 1 This is a structural schematic diagram of a certain type of cage.

[0029] Figure 2 It is an inverted half-shaped ball-shaped pocket on a certain model of cage.

[0030] Figure 3 The forming blade used in existing technology.

[0031] Figure 4 To address the issue of using a forming tool to process corner protrusions caused by limitations in tool size in existing technologies.

[0032] Figure 5 This is a schematic diagram showing the position of ∠α.

[0033] Figure 6 This is a schematic diagram of the tool movement position during the semi-finish milling of hole #1.

[0034] Figure 7 The coordinate diagram of the subroutine when performing semi-finish milling on the contour of the #1 pocket. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention relates to a cage of a certain type of traction motor bearing, the structure of which is as follows: Figure 1 As shown, its pocket structure is an inverted half-shaped ball-shaped pocket, such as... Figure 2 As shown. In the prior art, the forming tool structure for processing the above-mentioned pocket is as follows. Figure 3 As shown, the cutting edge of the forming tool includes a straight shank cutting part with a diameter of d and a forming part with a maximum diameter of D. When using this forming tool to process the above-mentioned cage pocket hole, the problems exist as described in the background art.

[0037] To address the problems identified in the background art, this invention provides a CNC milling method for machining a square arc-shaped pocket on a cage, comprising the following steps:

[0038] Step S1, Machine tool and cutting tool selection; The machine tool selected is a five-axis vertical machining center, and the cutting tools selected are large-diameter end mills, small-diameter end mills, large-diameter ball end mills, and small-diameter ball end mills;

[0039] Step S2: Fix the cage on the A-axis so that the axis of the cage is collinear with the axis of the A-axis;

[0040] Step S3: Rotate axis A so that the axis of the uppermost pocket of the cage is parallel to the Z-axis. Set the number of the uppermost pocket as 1#. Then, number the remaining pockets in a counterclockwise direction as 2#, 3#, ..., N#, where N is the total number of pockets of the cage. In the YZ plane where the center of pocket 1# is located, set the angle between the line connecting the midpoint of the upper left side of pocket 1# to the center of pocket 1# and the horizontal plane as ∠α. Measure the angle value β of ∠α.

[0041] Step S4: Install the large-diameter end mill on the Z-axis and use the large-diameter end mill to rough mill the overall contour of the #1 pocket hole;

[0042] After rough milling the overall contour of pocket #1 in step S5, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the angle θ between the center lines of the two adjacent pockets, so that pocket #2 is in the machining position. Use a large-diameter end mill to rough mill the overall contour of pocket #2.

[0043] Step S6: Following the overall contour machining steps of hole #2, use a large-diameter end mill to rough mill the overall contours of holes #3, ..., N in sequence;

[0044] Step S7: Reset the No. 1 pocket, change the Z-axis tool to a small diameter end mill, and use the small diameter end mill to machine the empty grooves at the four corners of the No. 1 pocket;

[0045] After the empty grooves at the four corners of pocket #1 are machined in step S8, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the angle θ between the center lines of two adjacent pockets, so that pocket #2 is in the machining position. Use a small-diameter end mill to rough mill the empty grooves at the four corners of pocket #2.

[0046] Step S9: Following the machining steps for the empty grooves at the four corners of the #2 pocket, use a small-diameter end mill to machine the empty grooves at the four corners of the #3, ..., N pockets in sequence;

[0047] Step S10: Reset the No. 1 pocket, change the Z-axis tool to a large diameter ball end mill, and perform semi-finish milling on the No. 1 pocket contour;

[0048] Step S11: After the semi-finish milling of the 1# pocket contour is completed, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the included angle θ between the center lines of the two adjacent pockets, so that the 2# pocket is in the machining position. Use a large diameter ball end mill to semi-finish mill the 2# pocket contour.

[0049] Step S12: Following the semi-finish milling steps for the 2# pocket contour, use a large-diameter ball end mill to sequentially semi-finish mill the 3#, ..., N# pocket contours;

[0050] Step S13: Reset the #1 pocket, change the Z-axis tool to a small-diameter ball end mill; adjust the tool compensation parameters, and repeat steps S10 to S12 to finish mill the contours of pockets #1, #2, #3, ... N in sequence.

[0051] In step S1, the cutting tool diameters are ordered as follows: large diameter end mill > large diameter ball end mill > small diameter ball end mill > small diameter end mill.

[0052] In step S4, the method for rough milling the overall contour of the No. 1 pocket hole with a large-diameter end mill is as follows: Z-axis layer milling is adopted, the depth of cut in a single Z-axis layer does not exceed 1 mm, and the allowance for each contour layer is 0.4-0.8 mm.

[0053] In step S7, the method for machining the empty grooves at the four corners of the No. 1 pocket hole with a small-diameter end mill is as follows: Z-axis layer milling is adopted, the depth of cut in a single Z-axis layer does not exceed 0.5 mm, and no allowance is left for each layer contour.

[0054] In step S10, the semi-finish milling method for pocket #1 is as follows: Based on the measured angle value β, rotate axis A clockwise until the rotation angle of axis A is equal to β. At this time, pocket #1 enters the machining position. After machining one side contour of pocket #1, the tool is lifted, and axis A is rotated counterclockwise to rotate axis A to the mirror position. Mirror machining is then used to mill the other side contour of pocket #1. Afterwards, the tool is lifted, axis A is reset, and the semi-finish milling of pocket #1 is completed. Figure 6 As shown, because the interference between the tool diameter and the pocket contour is eliminated, the tool path will not overcut the pocket contour.

[0055] In step S11, after the 2# pocket is in the machining position, its semi-finish milling method is the same as that of the 1# pocket.

[0056] Because the aforementioned bearing cage has a regular geometric structure, it is suitable for manual programming. According to the method provided by this invention, the manually programmed machining procedure is as follows:

[0057] Processing procedure and instructions:

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] The main program primarily completes... Figure 4 The subroutine calls for processing the n-divided pocket contour and forming the pocket sidewalls.

[0066] Subroutine description:

[0067]

[0068]

[0069]

[0070]

[0071] The coordinate graph of the above subroutine O0315 is as follows: Figure 7 As shown.

[0072] To finish mill a circular arc surface, simply change the tool diameter and initial value in the above subroutine to complete the machining of the circular arc surface of the pocket; further details are omitted.

[0073] The method of this invention is suitable for using macro programs to call subroutines and nested subroutines when compiling CNC programs, and can also utilize the CNC system's... Trigonometric function calculations and other product processing can now be performed in machining centers with 3+2 multi-axis linkage.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0075] The parts of this invention not described in detail are prior art.

Claims

1. A CNC milling method for machining a square arc-shaped pocket on a cage, characterized in that: Includes the following steps: Step S1, Machine tool and cutting tool selection; The machine tool selected is a five-axis vertical machining center, and the cutting tools selected are large-diameter end mills, small-diameter end mills, large-diameter ball end mills, and small-diameter ball end mills; Step S2: Fix the cage on the A-axis so that the axis of the cage is collinear with the axis of the A-axis; Step S3: Rotate axis A so that the axis of the uppermost pocket of the cage is parallel to the Z-axis. Set the number of the uppermost pocket as 1#. Then, number the remaining pockets in a counterclockwise direction as 2#, 3#, ..., N#, where N is the total number of pockets of the cage. In the YZ plane where the center of pocket 1# is located, set the angle between the line connecting the midpoint of the upper left side of pocket 1# to the center of pocket 1# and the horizontal plane as ∠α. Measure the angle value β of ∠α. Step S4: Install the large-diameter end mill on the Z-axis and use the large-diameter end mill to rough mill the overall contour of the #1 pocket hole; After rough milling the overall contour of pocket #1 in step S5, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the angle θ between the center lines of the two adjacent pockets, so that pocket #2 is in the machining position. Use a large-diameter end mill to rough mill the overall contour of pocket #2. Step S6: Following the machining steps for the overall contour of pocket #2, use a large-diameter end mill to rough mill the overall contours of pockets #3, ..., N in sequence; Step S7: Reset the No. 1 pocket, change the Z-axis tool to a small diameter end mill, and use the small diameter end mill to machine the empty grooves at the four corners of the No. 1 pocket; After the empty grooves at the four corners of pocket #1 are machined in step S8, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the angle θ between the center lines of two adjacent pockets, so that pocket #2 is in the machining position. Use a small-diameter end mill to rough mill the empty grooves at the four corners of pocket #2. Step S9: Following the machining steps for the empty grooves at the four corners of the #2 pocket, use a small-diameter end mill to machine the empty grooves at the four corners of the #3, ..., N pockets in sequence; Step S10: Reset the No. 1 pocket, change the Z-axis tool to a large-diameter ball end mill, and perform semi-finish milling on the No. 1 pocket contour; Step S11: After the semi-finish milling of the 1# pocket contour is completed, lift the tool and rotate the A-axis clockwise. The rotation angle of the A-axis is equal to the included angle θ between the center lines of the two adjacent pockets, so that the 2# pocket is in the machining position. Use a large diameter ball end mill to semi-finish mill the 2# pocket contour. Step S12: Following the semi-finish milling steps for the 2# pocket contour, use a large-diameter ball end mill to sequentially semi-finish mill the 3#, ..., N# pocket contours; Step S13: Reset the #1 pocket, change the Z-axis tool to a small diameter ball end mill; adjust the tool compensation parameters, and repeat steps S10 to S12 to finish mill the contours of pockets #1, #2, #3, ... N in sequence.

2. The CNC milling method for a cage with a square arc-shaped pocket according to claim 1, characterized in that: In step S1, the cutting tool diameters are ordered as follows: large diameter end mill > large diameter ball end mill > small diameter ball end mill > small diameter end mill.

3. The CNC milling method for a cage with a square arc-shaped pocket according to claim 1, characterized in that: In step S4, the method for rough milling the overall contour of the No. 1 pocket hole with a large-diameter end mill is as follows: Z-axis layer milling is adopted, the depth of cut in a single Z-axis layer does not exceed 1 mm, and the allowance for each layer contour is 0.4-0.8 mm.

4. The CNC milling method for a cage with a square arc-shaped pocket according to claim 1, characterized in that: In step S7, the method for machining the empty grooves at the four corners of the #1 pocket with a small-diameter end mill is as follows: Z-axis layer milling is adopted, the depth of cut in a single Z-axis layer does not exceed 0.5 mm, and no allowance is left for each layer contour.

5. The CNC milling method for a cage with a square arc-shaped pocket according to claim 1, characterized in that: In step S10, the semi-finish milling method for the #1 pocket is as follows: Based on the measured angle value β, rotate axis A clockwise. The rotation angle of axis A is equal to β. At this time, the #1 pocket enters the machining position. After machining one side contour of the #1 pocket, the tool is lifted, and axis A is rotated counterclockwise to rotate axis A to the mirror position. Mirror machining is used to mill the other side contour of the #1 pocket. After that, the tool is lifted, axis A is reset, and the semi-finish milling of the #1 pocket ends.

6. The CNC milling method for a cage with a square arc-shaped pocket according to claim 1, characterized in that: In step S11, after the 2# pocket is in the machining position, its semi-finish milling method is the same as that of the 1# pocket.

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