A new energy vehicle rear end cover blind hole bearing hole processing technology

Abstract

The present invention discloses a blind hole bearing hole processing technology for the rear end cover of a new energy vehicle, comprising the following steps: S1 clamping the rear end cover workpiece on a fixed fixture to make its end face horizontal; S2 using a rough machining tool to perform rough machining of the bearing hole, hollowing out the axis position at the bottom of the rough machining tool to avoid the raised part at the bottom of the bearing hole; S3 cleaning the rough machined bearing hole; S4 turning on the internal cooling of the finishing tool, ensuring that the external spray of the equipment is closed, and moving the finishing tool to the initial position of the machining hole opening; taking the end face of the rear end cover workpiece as 0 mm, the initial position is 0mm~5mm in the positive direction of the z-axis; first machining to a distance of 1mm~3mm from the target depth; then reducing the feed speed to machine to the target depth. The blind hole bearing hole processing technology of the present invention can avoid the situation that aluminum chips cannot be discharged when the external cooling and the internal cooling are turned on at the same time, and ensure the machining accuracy. Through the optimized design of process parameters and tools, the high precision requirements such as the roundness, straightness, and roughness of the bearing hole can be guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of die-cast aluminum alloy machining, and specifically relates to a processing technology for a blind hole bearing hole of a rear end cover of a new energy vehicle. Background Art

[0002] At present, with the rapid development of new energy vehicles and the diversity of automobile products, the product structure of new energy vehicles is becoming more and more complex, and the processing precision requirements are high. The coaxiality of multi-level bearing holes is required to be 0.05, and the roundness and straightness of the bearing holes are required to be 0.006 (the processing tool is a tool body + flange tool body structure).

[0003] The traditional processing technology is to process the surface first and then the hole. During the processing, both external and internal cooling are turned on to ensure chip removal, cooling and lubrication. However, this process is suitable for through-hole processing, but not for processing the bearing hole (blind hole) of the rear end cover. The reference surface, hole and bearing hole (blind hole) of the rear end cover are at the same angle. The aluminum chips generated by the first processing surface will fall into the bottom of the bearing hole (blind hole) to be processed. When the bearing hole (blind hole) is processed again, the aluminum chips that fall into the processing surface cannot be discharged, which will cause scratches on the wall of the bearing hole of the rear end cover, poor dimensional accuracy and large wear on the blade; when processing the bearing hole (blind hole) at the same time, the external and internal cooling are turned on. The internal cooling of the tool discharges the aluminum chips from the bottom to the top, and the external cooling sprays from the top to the bottom, which makes the aluminum chips unable to be discharged, and also causes scratches on the wall of the bearing hole of the rear end cover, and poor dimensional accuracy. Summary of the invention

[0004] In response to one or more of the above defects or improvement needs in the prior art, the present invention provides a blind hole bearing hole processing technology for the rear end cover of a new energy vehicle. During fine processing, only the internal cooling is turned on and the external cooling is kept closed, thereby avoiding the situation where aluminum chips cannot be discharged when both the external cooling and the internal cooling are turned on at the same time, thereby ensuring the processing accuracy.

[0005] To achieve the above object, the present invention provides a new energy vehicle rear end cover blind hole bearing hole processing process, comprising the following steps:

[0006] S1: Clamp the rear end cover workpiece on the fixing fixture so that its end surface is horizontal;

[0007] S2 uses a rough machining tool to perform rough machining of the bearing hole. The axis position at the bottom of the rough machining tool is hollowed out to avoid the raised part at the bottom of the bearing hole.

[0008] S3 cleans the rough-machined bearing hole;

[0009] S4 turns on the internal cooling of the finishing tool, ensures that the external spray of the equipment is closed, and moves the finishing tool to the initial position of the processing hole opening; the end face of the rear end cover workpiece is 0 mm, and the initial position is 0mm ~5mm in the positive direction of the z-axis;

[0010] At a speed of 1500±250r / min and a feed rate of 100±50mm / min, the finishing tool is moved down along the negative direction of the Z axis to a depth of 1mm to 3mm from the target;

[0011] At a rotation speed of 1500±250r / min and a feed speed of 40±10mm / min, the finishing tool is lowered along the negative direction of the Z axis to the target depth;

[0012] At a rotation speed of 1500±250r / min and a feed speed of 100±50mm / min, the finishing tool is moved upward along the positive direction of the Z axis to the initial position, and the finishing of the bearing hole is completed.

[0013] As a further improvement of the present invention, the bearing hole includes a first bearing hole and a second bearing hole, the depth of the second bearing hole is greater than the depth of the first bearing hole, the second bearing hole is first processed according to steps S1 to S4, and then the first bearing hole is processed according to steps S2 to S4.

[0014] As a further improvement of the present invention, in step S2, during rough machining, the single-side allowance of the bearing hole diameter is 0.1 mm to 0.2 mm, and the allowance at the bottom of the hole is 0.1 mm to 0.3 mm.

[0015] As a further improvement of the present invention, in step S2, during rough machining, external cooling of the machining machine tool and internal cooling of the rough machining tool are simultaneously turned on.

[0016] As a further improvement of the present invention, the rough machining tool is a single diameter roughing blade or a combination of roughing blades with different diameters, which corresponds to the number of stages of the bearing holes.

[0017] As a further improvement of the present invention, the finishing tool includes one tool body or multiple tool bodies, corresponding to the number of levels of bearing holes that need to be finished, and the number of tool bodies is not greater than the total number of bearing holes; the multiple tool bodies are arranged in sequence along the axial direction, and the diameters decrease in sequence to match the multi-level apertures.

[0018] As a further improvement of the present invention, the tool body of the finishing tool includes guide bars arranged circumferentially thereof and blades arranged staggered from the guide bars, and the distance between the guide bars and the vertical axis of the tool body is smaller than the distance between the blades and the vertical axis of the tool body.

[0019] As a further improvement of the present invention, in the finishing tool, the cutting edge of the blade needs to be higher than the blade tail in the radial direction.

[0020] As a further improvement of the present invention, the rough machining tool is an integrated structure of a tool handle and a tool body; the tool body of the fine machining tool is connected to the tool handle via a flange.

[0021] As a further improvement of the present invention, after finishing the bearing hole, the reference surface and the reference hole are processed.

[0022] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

[0023] (1) The blind hole bearing hole processing process of the rear end cover of a new energy vehicle of the present invention processes the reference surface and the hole first, and then processes the bearing hole, so as to avoid the problem that the aluminum chips falling into the bearing hole from the processed surface cannot be discharged, resulting in scratches on the wall of the bearing hole of the rear end cover. In addition, during fine processing, only the internal cooling is turned on and the external cooling is kept off, so as to avoid the situation that the aluminum chips cannot be discharged when both the external cooling and the internal cooling are turned on.

[0024] (2) The blind hole bearing hole processing process of the rear end cover of a new energy vehicle of the present invention is to process the deeper bearing holes first and then the shallower bearing holes when there are multiple bearing holes. This can avoid the situation where the aluminum chips cut from the smaller bearing holes fall into the deeper bearing holes when the smaller bearing holes are processed first, thereby affecting the processing thereof.

[0025] (3) The blind hole bearing hole processing technology of the rear end cover of new energy vehicles of the present invention completes the fine processing of the bearing hole, and then processes the reference surface, reference hole and other fine processing parts, thereby avoiding the problem that aluminum chips falling into the processing surface cannot be discharged, resulting in scratches on the wall of the rear end cover bearing hole and poor precision.

[0026] (4) The blind hole bearing hole processing process of the rear end cover of a new energy vehicle of the present invention uses a rough processing tool corresponding to the number of the bearing holes, and a finishing tool corresponding to the number of the bearing holes that need to be finished. One tool can process multiple levels of bearing holes at the same time, effectively ensuring the coaxiality requirements of the bearing holes.

[0027] (5) The blind hole bearing hole processing technology of the rear end cover of a new energy vehicle of the present invention can ensure the high precision requirements of the roundness, cylindricity, straightness, parallelism, roughness, etc. of the bearing hole through the optimization design of process parameters and tools, while ensuring the position requirements of the bearing hole and the reference surface and hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the rear end cover structure of an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the installation of the rear end cover and the fixing fixture of an embodiment of the present invention;

[0030] Figure 3 is a cross-sectional view of a bearing hole according to an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of the rough machining tool structure of an embodiment of the present invention;

[0032] Figure 5A schematic diagram of the structure of a finishing tool according to an embodiment of the present invention;

[0033] Figure 6 A schematic diagram of a finishing tool blade and a tool tail according to an embodiment of the present invention;

[0034] Figure 7 is a processing schematic diagram corresponding to step S41 of an embodiment of the present invention;

[0035] Figure 8 is a processing schematic diagram corresponding to step S42 of an embodiment of the present invention;

[0036] Fig. 9 is a processing schematic diagram corresponding to step S43 of an embodiment of the present invention;

[0037] Fig.10 It is a processing schematic diagram corresponding to step S44 of an embodiment of the present invention.

[0038] In all the drawings, the same figure marks represent the same technical features, specifically: 1-rear end cover workpiece, 2-fixing fixture, 3-first bearing hole, 4-second bearing hole, 5-roughing tool, 6-finishing tool; 51-first roughing blade, 52-second roughing blade, 53-third roughing blade; 61-first tool body unit, 611-first guide bar, 612-first blade; 62-second tool body, 621-second guide bar, 622-second blade; 63-conduit. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] The blind hole bearing hole processing process of the rear end cover of a new energy vehicle according to the embodiment of the present invention is suitable for blind hole bearing hole processing, and comprises the following steps:

[0045] S1: Clamp the rear end cover workpiece on the fixing fixture so that its end surface is horizontal;

[0046] This step can be performed using a fixing fixture of the prior art, such as Figure 2 As shown, a specific embodiment of the present invention provides a specific clamp that uses a hydraulic cylinder to clamp the workpiece, but is not limited to this structure. As long as the end face of the rear end cover workpiece can be horizontally fixed, the error caused by the flipping of the clamp can be avoided, and the position and size of the bearing hole can be better guaranteed.

[0047] S2 bearing hole rough machining;

[0048] Use rough machining tools to perform rough machining of the bearing hole, hollow out the axis position at the bottom of the tool to avoid the raised part at the bottom of the bearing hole to prevent interference;

[0049] The single-side allowance of the bearing hole diameter is 0.1mm~0.2mm, preferably 0.15mm, and the allowance is processed by a finishing tool; the bottom allowance is 0.1mm~0.3mm, preferably 0.2mm, and the bottom allowance is preferably processed by a milling cutter rod.

[0050] The roughing tool is a single diameter roughing blade or a combination of roughing blades with different diameters, which corresponds to the number of stages of the bearing hole. In a specific embodiment of the present invention, three combination roughing tools with different diameters are used to perform roughing of the bearing hole. The roughing of the bearing hole has three processing parts with different diameters, and the present invention can complete the processing with the same tool. Figure 4 As shown, the present invention provides a specific schematic diagram of the roughing tool structure, the roughing tool comprises a first roughing blade 51, a second roughing blade 52, and a third roughing blade 53 of different diameters, which correspond to the three-level apertures of the bearing hole from top to bottom, respectively, and the roughing tool is used to process multiple levels of bearing holes at the same time. The middle part of the tool body is provided with a water inlet pipe along the axial direction, and the pipe passes through a plurality of branch pipes ( Figure 4 The middle dotted line represents a branch pipe) which leads water out from the corresponding blade.

[0051] Preferably, in this step, the external cooling of the processing machine tool and the internal cooling spray of the rough processing tool are turned on at the same time to facilitate rapid cooling. Since the subsequent finishing process is required, the external cooling and the internal cooling are used in this step. Even if the aluminum chips scratch the hole wall, it will not affect the rough processing. Without considering the influence of the aluminum chips, turning on the external cooling and the internal cooling at the same time can achieve rapid cooling.

[0052] S3 cleans the rough-machined bearing hole to prevent residual aluminum chips from affecting the fine machining;

[0053] The cleaning method may adopt existing technology, including but not limited to air gun blowing, cleaning liquid immersion, flushing, etc.

[0054] S4 bearing hole finishing;

[0055] When the spindle is stationary, the S41 finishing tool is turned on with internal cooling, and is moved to the initial position of the machining hole opening, with the end face of the rear end cover workpiece at 0 mm, and the initial position at 0mm to 5mm in the positive direction of the z-axis (the z-axis is the vertical direction, with upward as the positive direction and downward as the negative direction); preferably greater than 0mm, to maintain a safe height to avoid collision between the tool and the product to be processed.

[0056] It should be noted that in this step, the external spray of the equipment must be closed to prevent aluminum chips from being discharged.

[0057] S42, with a rotation speed of 1500±250r / min and a feed speed of 100±50mm / min, the finishing tool moves down along the negative direction of the Z axis to a depth of 1mm~3mm from the target;

[0058] S43, with a rotation speed of 1500±250r / min and a feed speed of 40±10mm / min, the finishing tool moves down along the negative direction of the Z axis to the target depth;

[0059] S44 rotates at a speed of 1500±250r / min and a feed speed of 100±50mm / min. The finishing tool moves upward along the positive direction of the Z axis to the initial position, and the bearing hole finishing is completed.

[0060] Furthermore, after the bearing hole is fine-machined, the reference surface, reference hole and other fine-machined parts are processed again, combined with the tool internal cooling structure processing, to avoid the aluminum chips that fall into the machined surface cannot be discharged, resulting in scratches on the wall of the rear end cover bearing hole and poor accuracy.

[0061] The finishing tool includes one or more cutter bodies, which specifically correspond to the number of levels of finishing required for the bearing hole, so the number of cutter bodies is not greater than the total number of bearing holes; the multiple cutter bodies are arranged in sequence along the axial direction, and the diameters decrease in sequence to match the multi-level apertures.

[0062] like Figure 5 As shown, the present invention provides a specific finishing tool 6, which has two processing parts with different diameters for finishing the bearing hole. Correspondingly, the tool body of the finishing tool 6 includes a first tool body unit 61 and a second tool body 62 arranged at the bottom thereof. The diameter of the first tool body unit 61 is larger than the diameter of the second tool body 62. The first tool body unit 61 and the second tool body 62 correspond to the first-level aperture and the third-level aperture of the bearing hole from top to bottom, respectively, and are used for finishing the same. Since the second-level aperture of the bearing hole has a lower precision requirement in this embodiment, it can be finished in one step during group processing. In this step, the first tool body unit 61 and the second tool body 62 can be used to finish the other two levels of apertures.

[0063] The present invention adopts a finishing tool with the number of tool bodies corresponding to the finishing stages of the multi-stage bearing holes. The same finishing tool can process the multi-stage bearing holes at the same time, effectively ensuring the coaxiality requirements of the two diameters.

[0064] The first tool body unit 61 includes a first guide bar 611 and a first blade 612, and the second tool body 62 includes a second guide bar 621 and a second blade 622. The guide bars are evenly distributed circumferentially on the corresponding tool body, and the blades are installed on the tool body with the guide bars staggered. The blade of the finishing tool is preferably an adjustable tool holder, and the radial size of the blade is adjusted by a top screw.

[0065] Preferably, the distance between the finishing tool guide bar and the vertical axis of the tool body is smaller than the distance between the blade and the vertical axis of the tool body, and the difference between the two is preferably 0.003mm~0.01mm, so as to ensure that the blade can cut smoothly while the guide bar plays a supporting role, ensuring the roundness and straightness requirements of the bearing hole. Figure 5 As shown, taking the second blade body 62 as an example, the distance a between the second guide bar 621 and the vertical axis of the blade body is smaller than the distance b between the second blade 622 and the vertical axis of the blade body.

[0066] Preferably, the blade edge of the blade needs to be higher than the blade tail in radial direction to avoid the blade tail interfering with the hole wall after the blade edge cuts, causing scratches on the hole wall; Figure 6 As shown, the radial difference c between the cutting edge and the cutting tail of the first blade 612 and the second blade 622 is preferably 0.015 mm.

[0067] Furthermore, a conduit 63 is provided in the middle of the blade body along the axial direction, a water inlet is provided at the top thereof to communicate with the outside of the blade body, and a plurality of branch pipes are connected at the bottom thereof ( Figure 5 The middle dotted line represents the branch pipe), the pipe opening of the branch pipe corresponds to the corresponding blade position, the coolant hole in the tool for finishing the bearing hole is sprayed onto the blade and the guide bar, and the blind hole is blocked to flush the aluminum chips out of the hole in the reverse direction.

[0068] Preferably, the axis center position at the bottom of the finishing tool is hollowed out to avoid the raised part at the bottom of the bearing hole to prevent interference.

[0069] Preferably, the rough machining tool 5 is an integrated structure of a tool handle and a tool body, which can enhance the overall strength of the tool and is suitable for rough machining.

[0070] Preferably, the body of the finishing tool 6 is connected to the tool holder 64 by a flange, which is convenient for adjusting the tool runout. When the finishing tool is installed on the machine tool spindle, the runout of the finishing tool holder on the spindle needs to be calibrated before use. Through flange fine-tuning, the runout is preferably adjusted to ≤0.003mm. Further preferably, when the finishing tool and the machine tool spindle are installed, the two are installed in a fixed direction, which can be achieved by setting guide grooves or guide marks, etc., to avoid errors caused by different installation directions.

[0071] The blind hole bearing hole of the rear end cover of the new energy vehicle includes at least one bearing hole. In the specific embodiment shown in the drawings of the present invention, it includes a first bearing hole 3 and a second bearing hole 4 of different depths. The depth of the second bearing hole 4 is greater than the depth of the first bearing hole 3. The multi-level apertures of the two are the same, and the same size of rough machining tool 5 and finishing tool 6 can be used. Preferably, the second bearing hole 4 is first processed according to the above steps S1 to S4, and then the first bearing hole 3 is processed according to steps S2 to S4, so as to avoid the aluminum chips cut from falling into the bearing hole with a larger depth when the bearing hole with a smaller depth is processed first, thereby affecting its processing.

[0072] The blind hole bearing hole processing technology of the rear end cover of the new energy vehicle of the present invention firstly rough-processes the bearing hole (blind hole) and then fine-processes the bearing hole (blind hole). During fine processing, since the bearing hole of the rear end cover is a blind hole, aluminum chips cannot fall out from the bottom of the hole. The guide bar boring tool for fine processing of the bearing hole (blind hole) needs to be designed with an internal cooling structure. In addition, the equipment does not turn on the external spray during processing to prevent the external spray from pressing the aluminum chips into the bearing hole; after the processing is completed, the fine processing tool is retracted, and the retraction speed is the same as the processing speed. After the tool completely withdraws from the product, the spindle stops rotating and the processing is completed. When the present invention fine processes the bearing hole (blind hole), the guide bar tool internal cooling spray is used to discharge the aluminum chips backwards, and the external spray of the equipment is not turned on to discharge the aluminum chips smoothly out of the hole. In addition, the roundness, cylindricity, straightness, parallelism, roughness and other requirements of the bearing hole are guaranteed by combining the process parameters and the optimized design of the tool.

[0073] The following is a specific embodiment provided by the present invention. In this embodiment, the blind hole bearing hole processing process of the rear end cover of the new energy vehicle includes the following steps:

[0074] First, clamp the workpiece on the hydraulic fixture, and the hydraulic cylinder clamps the workpiece, which is the rear end cover; the product is clamped on the hydraulic fixture, and the product always remains in a horizontal state.

[0075] Then the bearing hole is rough-machined. The roughing tool body and the tool handle are an integrated structure to strengthen the tool structure. The tool body is equipped with multiple roughing tool blades to process three multi-level bearing holes with different diameters. The axial position at the bottom of the tool is hollowed out to avoid the raised part at the bottom of the bearing hole to prevent interference; the single-side allowance of the bearing hole diameter is 0.15mm, and the allowance at the bottom of the hole is 0.2mm.

[0076] Then finish the bearing hole. There are two processing parts with different diameters in the finishing bearing hole, which are completed with the same tool. The finishing tool body and the tool handle are flange-connected, which is convenient for adjusting the tool runout; the two diameters are on the same tool body, which effectively guarantees the coaxiality requirements of the two diameters; at the same time, the blade of the finishing tool is adjusted to be 0.003mm higher than the boring blade, and the blade and the tail of the boring blade are required to be 0.015mm higher than the tail; after adjustment, the finishing tool is in the spindle static state, and the finishing bearing hole guide bar tool internal cooling is turned on and Turn off the external spray of the equipment, and quickly move to +5mm above the machining hole opening; maintain the safe height, rotate at 1500r / min, feed at 100mm / min, and move the finishing tool down to -38mm in the negative direction of the Z axis; slow down the feed from 100mm / min to 40mm / min, and move the finishing tool down to -40mm in the negative direction of the Z axis; then move the finishing tool upward along the positive direction of the Z axis at a feed speed of 100mm / min to the position +5mm above the machining hole opening, and the bearing hole finishing is completed.

[0077] According to the above method, the bearing hole with a deeper depth is processed first, and then the bearing hole with a shallower depth is processed.

[0078] After finishing the bearing hole, further process the reference surface, hole and other parts.

[0079] It will be easily understood by those skilled in the art that 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A new energy vehicle rear end cover bearing hole processing technology, the reference surface, reference hole and bearing hole of the rear end cover are at the same angle, and the bearing hole is a blind hole; characterized in that: The steps include: S1: Clamp the rear end cover workpiece on the fixing fixture so that its end surface is horizontal; S2 uses a rough machining tool to perform rough machining of the bearing hole. The axis position at the bottom of the rough machining tool is hollowed out to avoid the raised part at the bottom of the bearing hole. During rough machining, the external cooling of the processing machine tool and the internal cooling of the rough machining tool are turned on at the same time. S3 cleans the rough-machined bearing hole; S4 turns on the internal cooling of the finishing tool, and ensures that the external spray of the equipment is closed to avoid the situation where aluminum chips cannot be discharged when the external cooling and internal cooling are turned on at the same time; in the finishing tool, the blade of the blade must be higher than the tail of the tool in the radial direction; move the finishing tool to the initial position of the processing hole opening; the end face of the rear end cover workpiece is 0 mm, and the initial position is 0mm ~5mm in the positive direction of the z axis; At a speed of 1500±250r / min and a feed rate of 100±50mm / min, the finishing tool is moved down along the negative direction of the Z axis to a depth of 1mm to 3mm from the target; At a rotation speed of 1500±250r / min and a feed speed of 40±10mm / min, the finishing tool is lowered along the negative direction of the Z axis to the target depth; At a rotation speed of 1500±250r / min and a feed speed of 100±50mm / min, the finishing tool moves upward along the positive direction of the Z axis to the initial position, and the finishing of the bearing hole is completed; After finishing the bearing hole, the reference surface and reference hole are processed.

2. The new energy vehicle rear end cover bearing hole processing process according to claim 1 is characterized in that: The bearing hole includes a first bearing hole and a second bearing hole, the depth of the second bearing hole is greater than the depth of the first bearing hole, the second bearing hole is first processed according to steps S1 to S4, and then the first bearing hole is processed according to steps S2 to S4.

3. The new energy vehicle rear end cover bearing hole processing process according to claim 1 is characterized in that: In step S2, during rough machining, the single-side allowance of the bearing hole diameter is 0.1 mm to 0.2 mm, and the allowance at the bottom of the hole is 0.1 mm to 0.3 mm.

4. The new energy vehicle rear end cover bearing hole processing process according to claim 1, characterized in that: The rough machining tool is a single diameter roughing blade or a combination of roughing blades with different diameters, which corresponds to the number of stages of the bearing hole.

5. The new energy vehicle rear end cover bearing hole processing process according to claim 1, characterized in that: The finishing tool includes one or more tool bodies, corresponding to the number of levels of bearing holes that need to be finished, and the number of tool bodies is not greater than the total number of bearing holes; the multiple tool bodies are arranged in sequence along the axial direction, and the diameters decrease in sequence to match the multi-level apertures.

6. The process for machining the bearing hole of the rear end cover of a new energy vehicle according to any one of claims 1 to 5, characterized in that: The tool body of the finishing tool comprises guide bars arranged along the circumference thereof and blades arranged staggered from the guide bars, and the distance between the guide bars and the vertical axis of the tool body is smaller than the distance between the blades and the vertical axis of the tool body.

7. The process for machining the bearing hole of the rear end cover of a new energy vehicle according to any one of claims 1 to 5, characterized in that: The rough machining tool is an integrated structure of a tool handle and a tool body; the tool body and the tool handle of the finishing tool are connected via a flange.

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