Diesel engine part gland hole machining process

Abstract

A diesel engine part gland hole machining technology comprises the following steps that outer holes in the two ends of a gland hole are machined; an angle milling head is replaced to drill the oil hole with the axis forming an inclined angle with the axis of the gland hole; a forming boring cutter matched with the inner hole diameter and the chamfer angle is assembled on the main shaft; orienting a tool nose to an oil hole inclination angle, and feeding the tool nose into an inner cavity of the gland hole after radial reverse bias; and through radial positive deviation resetting, middle inner hole boring and inner and outer chamfering machining are completed in sequence. Burrs can be synchronously removed by drilling the oil hole and boring the hole, the whole-process machining is completed by a single tool, a facing head is not needed, the problem of tool interference is solved, the machining precision is high, the process is simplified, and the cost is greatly reduced and the efficiency is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of diesel engine manufacturing, and in particular relates to a machining process for grate holes in diesel engine parts. Background Technology

[0002] The glancing hole is a critical precision hole system located at the bottom of the diesel engine cylinder block, used to install the piston rod stuffing box and guide the reciprocating motion of the piston rod. Structurally, it is a typical irregular stepped hole, exhibiting a special shape with small diameters at both ends and a large diameter in the middle. Simultaneously, an oblique lubricating oil hole is designed on the side wall of the middle section. The axis of this oil hole is at a predetermined angle to the vertical central axis of the glancing hole and orthogonally connected to the oil supply thread hole on the bottom surface of the cylinder block, thus creating a forced lubrication channel for the piston rod and stuffing box friction pair. Due to the combined constraints of the stepped structure and the spatially oblique oil hole, the glancing hole cannot be directly machined using conventional through-hole boring processes. During machining, problems such as tool interference, hole wall scratches, oil hole position misalignment, and insufficient chamfering accuracy are highly likely to occur. It is one of the most difficult and precision-controlled critical processes in cylinder block machining.

[0003] Currently, the industry mainly uses two types of process routes for processing this type of glancing hole:

[0004] Machining is performed on a CNC boring machine using a rotary table in conjunction with a cutting tool. The control system drives the rotary table to guide the tool through complex radial tool paths, thereby achieving the forming of stepped holes and positive and negative chamfers. This solution relies on high-cost accessories such as rotary tables, resulting in large equipment investment, complex programming and debugging, and high skill requirements for operators. Furthermore, the long tool overhang and poor rigidity during machining make it prone to vibration and tool deflection, making it difficult to consistently guarantee the hole wall roughness and geometric tolerances.

[0005] The current CNC machine tool employs a multi-tool sequential machining process. First, rough boring is performed on the overall hole positions. Then, a forming disc milling cutter is installed on the spindle, and rough machining is completed along the trajectory of the large central hole through two-axis linkage. Finally, a fine boring tool and a chamfering tool are used sequentially to finish machining the reference holes at both ends and the inner and outer chamfers, respectively. This approach involves cumbersome procedures and numerous tool changes. Multiple clamping and tool changes introduce cumulative positioning errors, resulting in poor consistency in key precision aspects such as coaxiality and chamfer angles. Consequently, the machining efficiency is low and the production cost is high.

[0006] Both of the aforementioned traditional processes employ a procedure of first machining the central large hole and then drilling the oblique lubricating oil hole. The burrs and flanges generated during oil hole drilling are located on the already machined hole wall surface, making them difficult to remove. These burrs can easily scratch the piston rod and damage the sealing ring during diesel engine operation, and may even cause oil passage blockage, affecting lubrication and sealing reliability. Furthermore, the inherent defects of multiple tool changes, complex path control, and post-machining of the oil hole mean that the machining accuracy, production efficiency, and product consistency of the glancing hole cannot meet the high-quality, high-efficiency, and low-cost large-scale manufacturing requirements of modern large-scale low-speed diesel engines, thus hindering further improvements in the manufacturing level of key marine diesel engine components. Summary of the Invention

[0007] The purpose of this invention is to provide a machining process for gland holes in diesel engine parts, in order to solve the technical problems of existing gland hole machining processes, such as the inability to adapt conventional boring methods, easy interference and scratching of cutting tools, difficulty in removing burrs from oil holes, cumbersome procedures, and difficulty in ensuring stable forming accuracy.

[0008] To achieve the above objectives, the specific technical solution of the present invention for machining the gland hole of a diesel engine part is as follows:

[0009] A machining process for a glancing hole in a diesel engine part, wherein the glancing hole is a stepped hole located at the bottom of the diesel engine cylinder block, the diameter of the outer holes at both ends is smaller than the diameter of the inner hole in the middle, and the inner hole is connected to an oil hole. The machining process for the glancing hole includes the following steps:

[0010] S1. External hole machining: The pre-set glancing hole reference hole of the cylinder block is machined in sequence, and the external hole diameter of the reference hole is machined.

[0011] S2. Oil hole machining: Replace the angle milling head and drill the oil hole. The axis of the oil hole is inclined at an angle to the axis of the grate hole.

[0012] S3. Tool assembly: A forming boring tool is assembled on the spindle of the CNC machine tool. The forming angle of the cutting edge of the forming boring tool matches the inner and outer chamfers to be machined in the glan hole, and the outer diameter of the machining tool matches the inner diameter of the glan hole.

[0013] S4. Tool positioning: Orient the tip of the forming boring tool to an inclination angle consistent with the axis of the oil hole, control the tip to deviate in the opposite radial direction, and feed the forming boring tool into the inner cavity of the grate hole along the axis of the grate hole, so that the tip is coaxial with the axis of the oil hole.

[0014] S5. Internal hole machining: Control the tip of the forming boring tool to deviate in the positive radial direction, and perform reciprocating cutting along the axial direction of the grate hole to bore the internal hole of the grate hole;

[0015] S6. Internal chamfering: Orient the tip of the forming boring tool to be parallel to the central axis of the grate hole, control the tip to deviate in the opposite radial direction, feed the forming boring tool into the grate hole to the internal chamfering depth, control the tip to deviate in the positive radial direction, and complete the internal chamfering of the grate hole.

[0016] S7. External chamfering: Orient the tip of the forming boring tool to be parallel to the central axis of the glan hole, control the tip to deviate in the opposite radial direction, move the forming boring tool axially to the reference positions on both outer end faces of the glan hole, and control the tip to deviate in the positive radial direction to complete the external chamfering of the glan hole.

[0017] As a further improvement of the present invention, the bottom of the diesel engine cylinder block is provided with an oil inlet for conveying lubricating oil, and the oil inlet is connected to the oil hole.

[0018] As a further improvement of the present invention, the forming boring tool enters the glancing hole from the bottom of the cylinder block, and the inner chamfer of the glancing hole near the bottom of the cylinder block is a proximal inner chamfer. The single-sided wall of the oil hole is located within the proximal inner chamfer, extends from the glancing hole to the oil inlet hole and is orthogonal to the oil inlet hole.

[0019] As a further improvement of the present invention, the outer hole diameter is 280mm to 285mm, the oil hole diameter is 15mm to 17mm, and the inner hole diameter is 286mm to 295mm.

[0020] As a further improvement of the present invention, the inclination angle between the oil hole axis and the center axis of the gland hole is 15° to 20°.

[0021] As a further improvement of the present invention, the chamfer angle inside the glancing hole is 20° to 25°.

[0022] As a further improvement of the present invention, the radial deviation of the tip of the forming boring tool is 5mm to 8mm.

[0023] As a further improvement of the present invention, the inner hole diameter is 283mm, the oil hole diameter is 16mm, the outer hole diameter is 289mm, the tilt angle is 17°, the chamfer angle is 20°, the principal cutting edge angle of the forming boring tool is 20°, and the radial deviation of the forming boring tool tip is 5mm.

[0024] As a further improvement of the present invention, the same forming boring tool is used to complete S3 to S7, and there is no tool changing operation during the processing.

[0025] As a further improvement of the present invention, the forming boring tool is a single-edged boring tool, whose cutting angle is matched with the angle of the chamfer to be processed, so as to simultaneously complete the boring cutting and chamfer forming processing.

[0026] Beneficial effects:

[0027] This invention employs a process flow that first completes the finishing of the outer holes at both ends of the gland hole, drills the oblique oil holes, and finally bores the middle inner hole, completely different from the conventional machining route of boring the inner hole first and then drilling the oil holes in existing technologies. The subsequent boring of the middle inner hole directly removes burrs and flanges generated on the inner wall of the gland hole during the oil hole drilling process, eliminating the need for a separate deburring process. This completely avoids problems such as piston rod scratches, sealing ring damage, and lubrication circuit blockage caused by burr residue, significantly improving the machining quality of the gland hole and the lubrication and sealing reliability during diesel engine operation. Simultaneously, prioritizing the machining of the outer holes at both ends provides a unified benchmark for the subsequent oil hole drilling, inner hole boring, and chamfering process, ensuring the consistency of dimensional and positional accuracy of each machining step from the source of the process.

[0028] A tool tip orientation and radial deviation in the feed scheme solves the tool interference problem in machining irregular stepped holes. For irregular structures where the diameter of the outer holes at both ends of a grate hole is smaller than the diameter of the inner hole in the middle, the tool tip of the forming boring tool is oriented at an angle consistent with the axis of the oil hole. Combined with a radial deviation in the tool retraction action, the forming boring tool can pass through the smaller outer holes at both ends without contact or scratches and smoothly enter the inner cavity of the grate hole. At the same time, it completely avoids the already machined oblique oil hole, completely avoiding the problem of the tool scraping against the finished outer hole wall and damaging the oil hole structure during the tool entry and exit process. This solves the core problem that conventional boring processes cannot be adapted to the machining of irregular stepped holes.

[0029] This invention integrates the boring of the inner hole and the chamfering of both ends into a single forming process. By assembling a forming boring tool with a cutting edge forming angle that matches the chamfer to be machined and a machining outer diameter that matches the inner hole diameter of the grate hole, the boring of the inner hole of the grate hole and the forming of the inner and outer chamfers can be completed sequentially with the same tool. This eliminates the need for multiple tools to complete the boring and chamfering processes in sequence, greatly simplifying the machining process and avoiding the cumulative positioning errors caused by multiple tools and multiple processes. It can stably guarantee the forming accuracy and coaxiality of the inner hole and the chamfers at both ends. The machined hole wall and chamfer surface are free of defects such as tool marks and chipping, resulting in better forming quality.

[0030] The invention uses a unified machining benchmark throughout the entire process to ensure the overall machining accuracy and assembly compatibility of the gland hole. It uses the outer holes at both ends of the gland hole as a unified machining benchmark. Subsequent oil hole drilling, inner hole boring, and chamfering at both ends are all performed based on this benchmark. This can stably guarantee the form and position tolerances between the outer holes at both ends of the gland hole, the middle inner hole, the oblique oil hole, and the inner and outer chamfers. This ensures the assembly accuracy of the gland hole with the stuffing box and piston rod, provides a reliable guiding and sealing foundation for the stable reciprocating motion of the diesel engine piston rod, and improves the overall operating stability and service life of the diesel engine. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the bottom of the diesel engine cylinder block of the present invention;

[0032] Figure 2 In the processing technology S1 of the present invention Figure 1 AA section view;

[0033] Figure 3 In the processing technology S2 of the present invention Figure 1 AA section view;

[0034] Figure 4 In the processing technology S4 of the present invention Figure 1 AA section view;

[0035] The markings in the diagram are as follows: 1. Diesel engine cylinder block; 2. Gland hole; 21. Outer hole; 22. Inner hole; 23. Inner chamfer; 24. Outer chamfer; 3. Oil hole; 4. Oil inlet hole; 5. Oil hole; 6. Forming boring tool; 7. Inclined angle. Detailed Implementation

[0036] To better understand the purpose, structure, and function of this invention, the following detailed description of a machining process for a grate hole in a diesel engine part is provided in conjunction with the accompanying drawings.

[0037] Implementation example:

[0038] This embodiment discloses a machining process for gland holes in diesel engine parts, applicable to, for example... Figure 1 The shown section describes the machining of the grate hole 2 in the cylinder block 1 of a diesel engine. The low-speed diesel engine is the core power unit of ocean-going vessels, and the cylinder block is the basic load-bearing structural component of the diesel engine. The bottom of the cylinder block is an integrated transverse diaphragm structure, which completely separates the scavenging air box of the cylinder block from the crankcase cavity. The transverse diaphragm has a grate hole 2 opened in the vertical direction. The grate hole corresponds one-to-one with the cylinder liner hole on the upper end face of the cylinder block and is coaxially set. It is a core precision irregular hole used to install the piston rod stuffing box and provide precise guidance for the reciprocating motion of the piston rod.

[0039] The glan hole 2 is a stepped hole that runs vertically through the cylinder block. It has an irregular shape in which the diameter of the outer holes 21 at both ends is smaller than the diameter of the inner hole 22 in the middle. The outer hole that is closer to the bottom of the cylinder block is the proximal outer hole, and the outer hole that is farther away from the bottom and faces the inner cavity of the cylinder block is the distal outer hole. The outer holes 21 at both ends are the reference holes for the installation of the stuffing box and the machining of the glan hole 2. The inner hole in the middle is the lubricating oil reservoir and the piston rod movement clearance cavity.

[0040] An oil inlet hole 4 for conveying lubricating oil is provided on the lower end face of the cylinder block. In this embodiment, it is a G1 / 2 pipe thread hole, which is connected to the main lubrication oil passage of the diesel engine. An oblique oil hole 3 is provided on the side wall of the inner hole in the middle of the glancing hole 2. The single side wall of the oil hole 3 is located within the range of the inner chamfer 23 near the glancing hole. The oil hole 3 extends from the inside of the glancing hole 2 to the oil inlet hole 4. The axis of the oil hole 3 is inclined at a preset angle 7 with the vertical central axis of the glancing hole 2. In this embodiment, the inclination angle 7 between the axis of the oil hole 3 and the central axis of the glancing hole 2 is 17°. The axis of the oil hole 3 is orthogonal to the axis of the oil inlet hole 4, forming a forced lubrication channel for the piston rod-stuffing gland friction pair. The near end (close to the lower end face of the cylinder block bottom) and the far end (towards the inner cavity of the cylinder block) of the glancing hole 2 are respectively provided with inner end chamfers for guiding the stuffing gland assembly, preventing scratches on the piston rod movement, and eliminating stress concentration at the orifice.

[0041] In this embodiment, the machining equipment is a CNC floor-type boring machine equipped with spindle orientation function, CNC radial coordinate offset function, and angle milling head attachment. The entire machining process is completed on the same CNC machine tool. The specific process steps are as follows:

[0042] Step 1: Hoist the cylinder block onto the CNC boring machine table. Using the center of the cylinder liner hole on the upper end face of the cylinder block as the coaxiality reference, align the machining center of the grate hole 2, ensuring that the coaxiality between the grate hole 2 and the corresponding cylinder liner hole is ≤0.02mm. Then, complete the workpiece clamping and fixing. Figure 2 As shown, a rough boring tool is used to rough machine the reference holes at both ends of the glancing hole 2, leaving a 0.3mm finishing allowance on each side; then a fine boring tool is used to finish machine the reference holes at both ends, machining them to the designed hole diameter size φ283mm of the outer hole 21 of the glancing hole, providing a unified coaxiality and dimensional reference for subsequent machining processes.

[0043] Step Two, as follows Figure 3 As shown, after machining the two outer holes 21, the angle milling head is replaced on the CNC boring machine spindle. The machining posture of the angle milling head is adjusted so that the rotation axis of the drill bit is inclined at a 17° angle to the vertical center axis of the grate hole 2, which is completely coincident with the design axis of the oil hole. A φ16mm high-speed steel twist drill is used to drill the inclined oil hole 3. During the drilling process, the axis of the oil hole 3 is kept orthogonal to the axis of the oil inlet hole 4. The drill extends along the axis of the oil hole towards the oil inlet hole 4 to complete the machining of the oil hole 3.

[0044] Step 3: After machining oil hole 3, disassemble the angle milling head and assemble the forming boring tool 6 into the spindle taper hole of the CNC boring machine. In this embodiment, the forming boring tool 6 is a single-edged boring tool with a principal cutting edge angle of 20°, which perfectly matches the chamfer angle of the inner end of the grate hole to be machined. The maximum machining outer diameter of the boring tool is φ289mm, which matches the design diameter of the inner hole in the center of the grate hole. After clamping, execute the spindle orientation command to correct the initial 0° reference position of the tool tip. Subsequent processes are all completed using the same forming boring tool 6, and there is no tool change or re-tool setting operation during the machining process.

[0045] Step 4, as follows Figure 4 As shown, the spindle orientation command is executed, orienting the tip of the forming boring tool 6 to a 17° tilt angle 7 aligned with the axis of the oil hole and locking it. The spindle radial coordinate system is controlled by the CNC system to deviate the tip from the preset offset by 5mm in the opposite radial direction. At this point, the rotation diameter of the boring tool tip is reduced to φ279mm, smaller than the φ283mm diameter of the outer hole 21 of the grate hole, completing the tool deflection action. The spindle 5 is controlled to smoothly feed the forming boring tool into the inner cavity of the grate hole along the axial direction until the tip reaches the axial machining start position of the middle inner hole. At this point, the tip position is completely coaxial with the axis of the oil hole 3, with no contact or scratches throughout the process, completely avoiding the machined outer hole wall and oil hole structure, and without any tool interference.

[0046] Step 5: After the tool tip reaches the designated machining start position, the CNC system controls the spindle radial coordinate system to deviate the tool tip 5mm in the positive radial direction, resetting it to the designed cutting position of the inner hole 22 in the center of the grate hole. At this time, the rotation diameter of the tool tip returns to φ289mm. Start the spindle rotation, setting the spindle speed to 80r / min and the feed rate to 0.15mm / r. Control the spindle to drive the forming boring tool to perform reciprocating layered cutting along the axis of the grate hole, completing the boring of the inner hole in 3 layers, finally machining to the inner hole 22 with a diameter of φ289mm, ensuring that the coaxiality of the inner hole and the outer holes at both ends is ≤0.02mm, the cylindricity is ≤0.015mm, and the surface roughness Ra is ≤1.6μm. During the boring process, the burrs and flanges generated on the inner wall of the grate hole by the oil hole drilling are removed simultaneously, without the need for an additional dedicated deburring process.

[0047] Step Six: After completing the boring of the intermediate inner hole, the spindle stops rotating and the CNC system executes the spindle orientation command to orient the tip of the forming boring tool to a 0° reference position parallel to the center axis of the grate hole and lock it, providing a unified radial reference for subsequent chamfering. The CNC system adjusts the spindle radial coordinate system, controlling the tool tip to deviate from the preset offset by 5mm in the opposite radial direction. At this point, the rotation diameter of the forming boring tool tip is reduced to 279mm, smaller than the 283mm diameter of the outer holes at both ends of the grate hole, completing the tool deflection action and completely avoiding scraping against the finished inner hole wall and the upper outer hole during axial feed. The spindle is controlled to drive the forming boring tool to feed smoothly along the axial direction of the glancing hole until the designed machining depth of the inner chamfer 23 is reached (in this embodiment, the lower end face of the cylinder block is taken as the zero point, and the axial feed depth is 121mm, precisely corresponding to the transition step position between the middle inner hole and the upper outer hole of the glancing hole). After reaching the specified depth, the spindle radial coordinate system is adjusted again through the CNC system, and the tool tip is controlled to deviate 5mm in the positive radial direction, returning to the designed cutting position of the inner chamfer. At this time, the cutting edge of the forming boring tool with a 20° principal cutting edge angle is completely in contact with the surface to be machined for the inner chamfer 23. The spindle rotation is started, the spindle speed is set to 80r / min, and the feed rate is 0.15mm / r. The spindle is controlled to make a quantitative feed motion along the axial direction of the glancing hole to complete the forming machining of the inner end step chamfer of the glancing hole.

[0048] Step 7: After completing the machining of the inner chamfer 23, the spindle stops rotating and remains locked in the 0° reference position of the tool tip. No reorientation, tool change, or tool setting is required; the same forming boring tool is used throughout the machining process. The spindle radial coordinate system is adjusted again via the CNC system, controlling the tool tip to deviate 5mm from the preset offset in the radial direction, reducing the boring tool's rotation diameter to φ279mm again, completing the tool retraction action and preventing scraping against the already machined inner hole, inner chamfer 23, and hole wall structure during axial tool retraction. The spindle is controlled to smoothly retract the forming boring tool along the axial direction of the grate hole until it reaches the reference position on the near-end outer end face of the grate hole 2 (in this embodiment, the zero-point coordinate of the outer port of the grate hole on the lower end face of the cylinder block). After reaching the reference position, the tool tip is controlled to deviate 5mm in the positive radial direction, resetting to the designed cutting position for the outer chamfer, ensuring the forming cutting edge of the forming boring tool is fully engaged with the machined hole opening on the outer end face of the grate hole. Start the spindle 5 to rotate, maintain the same cutting parameters as the inner chamfer 23 machining, control the spindle to make a quantitative feed motion along the axis of the glan hole, and complete the forming machining of the outer chamfer 24 of the glan hole.

[0049] After the proximal outer chamfering is completed, the spindle stops rotating. The tool tip is then controlled to deflect 5mm in the opposite radial direction to complete the tool retraction. The spindle is then controlled to smoothly feed the forming boring bar along the axial direction of the glancing hole until it reaches the reference position on the far outer surface of the glancing hole (the position of the upper outer hole port facing the cylinder body cavity), precisely aligning it with the surface to be machined at the far outer hole opening. After reaching the reference position, the tool tip is controlled to deflect 5mm in the positive radial direction to return to the designed cutting position for the far outer chamfer, with the cutting edge of the forming boring bar engaging with the upper outer surface opening to be machined. The spindle is then started rotating, maintaining the same cutting parameters, and controlled to perform a quantitative feed motion along the axial direction to complete the forming of the outer chamfer on the far outer surface of the glancing hole, thus completing the entire chamfering process for the glancing hole.

[0050] The process of this invention adopts the following steps: first, process the outer holes at both ends, then drill the oil holes, and finally bore the middle inner hole. This is different from the traditional process of boring the inner hole first and then drilling the oil holes. The subsequent boring of the inner hole can remove the burrs of the oil holes at the same time, which completely avoids the risk of burrs leaving scratches on the piston rod and blockage of the oil passage. No additional deburring process is required, which greatly simplifies the processing steps.

[0051] This single-tool, multi-process integrated forming process completely eliminates cumulative errors. This process completes the entire machining process, including boring the inner hole and forming the inner and outer chamfers, with a single forming boring tool. There is no tool changing or re-tool setting, which completely avoids the positioning cumulative errors caused by multi-tool sequential machining. It can stably guarantee the coaxiality of the grate hole, chamfer angle and other key geometric tolerances, and significantly improve the consistency of product machining.

[0052] For irregular structures with small holes at both ends and a large hole in the middle, this process uses a combination of tool tip orientation matching the oil hole angle and radial forward and reverse deviation to allow a large-size boring tool to pass through the small-diameter outer hole without interference, completely avoiding the machined oil hole and the outer hole wall. This solves the core problem that conventional boring methods cannot be adapted to the machining of this irregular structure. It does not require high-cost special accessories such as a rotary table, and greatly reduces equipment investment and programming and debugging difficulty.

[0053] With a unified benchmark throughout the entire process, machining accuracy and assembly adaptability are significantly improved. This process uses the two outer holes at the two ends, which are prioritized for finishing, as a unified benchmark throughout the entire process. Subsequent oil hole drilling, inner hole boring, and chamfering are all performed based on this benchmark, which can stably guarantee the form and position tolerances between the various structures of the gland hole, ensure the assembly accuracy of the gland hole, stuffing box, and piston rod, provide a reliable guide and sealing foundation for the stable reciprocating motion of the diesel engine piston rod, and extend the service life of the entire machine.

[0054] With strong process compatibility and significantly reduced overall manufacturing costs, this process can complete all machining operations on a conventional CNC boring machine without the need for high-cost specialized equipment such as gantry milling machines. It also has a wide range of tool and equipment compatibility. At the same time, it significantly reduces non-cutting auxiliary time, shortens the single-hole machining cycle by more than 40% compared to traditional processes, and reduces tool procurement and maintenance costs by more than 60%. It has extremely high economic efficiency and engineering promotion value, and can fully cover the machining needs of grate holes for low-speed diesel engines of different specifications.

[0055] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A machining process for a grate hole in a diesel engine part, wherein the grate hole is a stepped hole located at the bottom of the diesel engine cylinder block, the diameter of the outer holes at both ends is smaller than the diameter of the inner hole in the middle, and the inner hole is connected to an oil hole, characterized in that, The processing technology of the glancing hole includes the following steps: S1. External hole machining: The pre-set glancing hole reference hole of the cylinder block is machined in sequence, and the external hole diameter of the reference hole is machined. S2. Oil hole machining: Replace the angle milling head and drill the oil hole. The axis of the oil hole is inclined at an angle to the axis of the grate hole. S3. Tool assembly: A forming boring tool is assembled on the spindle of the CNC machine tool. The forming angle of the cutting edge of the forming boring tool matches the inner and outer chamfers to be machined in the glan hole, and the outer diameter of the machining tool matches the inner diameter of the glan hole. S4. Tool positioning: Orient the tip of the forming boring tool to an inclination angle consistent with the axis of the oil hole, control the tip to deviate in the opposite radial direction, and feed the forming boring tool into the inner cavity of the grate hole along the axis of the grate hole, so that the tip is coaxial with the axis of the oil hole. S5. Internal hole machining: Control the tip of the forming boring tool to deviate in the positive radial direction, and perform reciprocating cutting along the axial direction of the grate hole to bore the internal hole of the grate hole; S6. Internal chamfering: Orient the tip of the forming boring tool to be parallel to the central axis of the grate hole, control the tip to deviate in the opposite radial direction, feed the forming boring tool into the grate hole to the internal chamfering depth, control the tip to deviate in the positive radial direction, and complete the internal chamfering of the grate hole. S7. External chamfering: Orient the tip of the forming boring tool to be parallel to the central axis of the glan hole, control the tip to deviate in the opposite radial direction, move the forming boring tool axially to the reference positions on both outer end faces of the glan hole, and control the tip to deviate in the positive radial direction to complete the external chamfering of the glan hole.

2. The machining process for the gland hole of a diesel engine part according to claim 1, characterized in that, The bottom of the diesel engine cylinder block is provided with an oil inlet for conveying lubricating oil, and the oil inlet is connected to the oil hole.

3. The machining process for the gland hole of a diesel engine part according to claim 2, characterized in that, The forming boring tool enters the glancing hole from the bottom of the cylinder block. The inner chamfer inside the glancing hole near the bottom of the cylinder block is a proximal inner chamfer. The single-sided wall of the oil hole is located inside the proximal inner chamfer, extending from the glancing hole to the oil inlet hole and perpendicular to the oil inlet hole.

4. The machining process for the gland hole of a diesel engine part according to claim 1, characterized in that, The outer hole diameter is 280mm to 285mm, the oil hole diameter is 15mm to 17mm, and the inner hole diameter is 286mm to 295mm.

5. The machining process for the gland hole of a diesel engine part according to claim 4, characterized in that, The inclination angle between the oil hole axis and the center axis of the glancing hole is 15° to 20°.

6. The machining process for the gland hole of a diesel engine part according to claim 5, characterized in that, The chamfer angle inside the glancing hole is 20° to 25°.

7. The machining process for the gland hole of a diesel engine part according to claim 6, characterized in that, The radial deviation of the forming boring tool tip is 5mm to 8mm.

8. The machining process for the gland hole of a diesel engine part according to claim 7, characterized in that, The inner hole diameter is 283mm, the oil hole diameter is 16mm, the outer hole diameter is 289mm, the tilt angle is 17°, the chamfer angle is 20°, the principal cutting edge angle of the forming boring tool is 20°, and the radial deviation of the forming boring tool tip is 5mm.

9. The machining process for the gland hole of a diesel engine part according to claim 1, characterized in that, The same forming boring tool is used to complete steps S3 through S7, and there is no tool changing operation during the machining process.

10. The machining process for the gland hole of a diesel engine part according to claim 1 or 9, characterized in that, The forming boring tool is a single-edged boring tool, whose cutting angle matches the angle of the chamfer to be processed, so as to simultaneously complete the boring cutting and chamfer forming process.

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