Method for machining starting valve hole and starting valve intake hole of marine diesel engine cylinder head

Abstract

A kind of processing method of starting valve hole and starting valve intake hole of marine diesel engine cylinder cover, comprising the following steps: one, processing starting valve hole, first pre-drilling prefabricated hole, then rough machining, after finishing starting valve hole to meet the requirements;Two, rough machining through hole, pre-drilling through hole and leaving margin, three, first inclined hole pre-processing, workpiece rotates to 6 ° position, drills minimum diameter prefabricated hole, four, second inclined hole pre-processing, workpiece rotates to-6 ° position, drills minimum diameter prefabricated hole, five, second inclined hole rough machining, using helical milling method, the rough machining of second inclined hole is carried out, diameter leaves 0.5mm margin, six, first inclined hole rough machining, workpiece turns back to 6 ° position, using helical milling method, the rough machining of first inclined hole is carried out, diameter leaves 0.5mm margin, seven, finishing first inclined hole, second inclined hole and through hole.The product quality of the present application is improved, the processing auxiliary time is reduced, and the processing efficiency is effectively improved, and it can be suitable for the processing of starting valve hole and starting valve intake hole of various types of cylinder cover.

Description

Technical Field

[0001] This invention relates to a processing method for large marine diesel engine components, and particularly to a processing method for the starter valve hole and starter valve intake hole in the cylinder head of a marine diesel engine, belonging to the field of diesel engine manufacturing technology. Background Technology

[0002] The starter valve port of the cylinder head of a large marine diesel engine runs through the cylinder head from top to bottom. Please refer to [link / reference]. Figure 1 The starting valve port 1 is a stepped through-hole; please refer to [link / reference]. Figure 2 The starter valve inlet 2 passes laterally through the cylinder head and connects with the starter valve hole 1. Machining the starter valve hole 1 only requires one drilling, one milling, and one boring operation. There is a sequence issue between machining the starter valve inlet 2 and machining the starter valve inlet 2. If the starter valve inlet 2 is machined first, the milling step of the starter valve hole 1 will need to be done in sections because a noticeable flange will be left when milling to the junction of the starter valve hole 1 and the starter valve inlet 2. This flange needs to be manually removed before further machining, otherwise it will cause tool wear. However, if the starter valve hole 1 is machined first and then the starter valve inlet 2, the final boring operation will result in less flange, which can then be removed by a fitter.

[0003] Taking the X92B cylinder head as an example, please refer to the relevant documentation. Figure 3 , Figure 4 and Figure 5 The structure of the starter valve intake port 2 consists of two parallel intersecting first oblique holes 41 and second oblique holes 42 connected to a through hole 5. The center distance between the starting points of the first oblique holes 41 and second oblique holes 42 is 16mm, their axes intersect at 12°, their diameter is 64mm, their depth is 383mm, and their surface finish requirement is Ra3.2. The inner ends of the first oblique holes 41 and second oblique holes 42 simultaneously communicate with the stepped hole 3 in the middle section of the starter valve port 1. The diameter of the stepped hole 3 is 140mm. The diameter of the through hole 5 is 80mm, and its outer end opens on the cylinder head surface. Because the intersecting first oblique holes 41 and second oblique holes 42 are intersecting and deep from beginning to end, when using traditional processes and tools for machining, there will inevitably be phenomena such as tool deflection, tool knocking, and inability to center. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a machining method for the starting valve hole and starting valve intake hole of the cylinder head of a marine diesel engine. This method solves the overcutting problem caused by tool deflection in traditional machining methods and reduces auxiliary time in the machine tool machining process by rationally arranging the machining route, thereby improving the effective cutting rate.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for machining a starter valve hole and a starter valve inlet hole in a marine diesel engine cylinder head, wherein the starter valve hole is a stepped through-hole penetrating the cylinder head, with a stepped hole in the middle section; the starter valve inlet hole is formed by parallel intersecting first and second oblique holes connecting to the through-hole, the through-hole opening onto the surface of the cylinder head, the axes of the first and second oblique holes intersecting at 12°, and their inner ends simultaneously penetrating the stepped hole; characterized in that the machining method includes the following steps:

[0007] Step 1: Machining the starter valve hole

[0008] First, a small-diameter indexable insert drill bit is used to pre-drill the minimum diameter through pre-drilled hole for spiral milling. Then, a high-feed milling cutter with an indexable insert and a mandrel-type vibration damping rod is used to rough-machine the remaining stepped holes in the starter valve hole according to the spiral trajectory. After that, the starter valve hole is finished by single boring and double boring to meet the drawing requirements.

[0009] Step 2: Rough machining of through holes

[0010] The through hole is pre-drilled using an indexable insert drill bit, leaving a margin, and then the hole opening is chamfered to complete the rough machining of the through hole;

[0011] Step 3: Pre-machine the first inclined hole

[0012] Rotate the workpiece to a 6° position so that the tool axis is at the same angle as the axis of the first inclined hole. First, use a small diameter spiral milling cutter to mill a flat surface at the bottom of the pre-made hole of the through hole. Then, drill the minimum diameter pre-made hole for spiral milling at the position of the first inclined hole, thereby completing the machining of the pre-made hole of the first inclined hole.

[0013] Step 4: Pre-machine the second inclined hole

[0014] Rotate the workpiece to a -6° position so that the tool axis is at the same angle as the axis of the second inclined hole. First, use a small diameter spiral milling cutter to mill a flat surface at the bottom of the pre-made hole of the through hole. Then, drill the minimum diameter pre-made hole for spiral milling at the position of the second inclined hole, thereby completing the machining of the pre-made hole of the second inclined hole.

[0015] Step 5: Rough machining of the second inclined hole

[0016] Using a high-speed milling cutter with a mandrel-type vibration damping rod, the cutter is started at a non-interference position in the second inclined hole. The machining method is helical milling, and the second inclined hole is roughed along the helical trajectory, leaving a diameter allowance of 0.5mm to facilitate subsequent finishing.

[0017] Step 6: Rough machining of the first inclined hole

[0018] The workpiece is rotated back to the 6° position so that the tool axis is at the same angle as the axis of the first inclined hole. A high-speed milling cutter with a mandrel-type vibration damping rod is used to start the cutter at a non-interference position of the first inclined hole. The first inclined hole is roughed by using a spiral milling method and following the spiral trajectory. A diameter allowance of 0.5 mm is left to facilitate subsequent finishing.

[0019] Step 7: Finish machining of the first inclined hole, the second inclined hole, and the through hole.

[0020] Using a double boring tool with a mandrel-type vibration damping rod, the first and second inclined holes are semi-finish bored, leaving a radius allowance of 0.3-0.4mm. Then, using a single boring tool with a damping anti-vibration rod, the first and second inclined holes are finely bored to meet the drawing requirements. The through holes are then precision machined using the same single and double boring methods to meet the drawing requirements.

[0021] Furthermore, in step one, the chamfer inside the starting valve hole is machined using a low-pitch spiral milling method.

[0022] Furthermore, in step seven, the drawings for the first and second oblique holes are required to have a surface finish of Ra3.2.

[0023] Compared with the prior art, the present invention achieves the following beneficial effects:

[0024] This invention solves the problems of tool deflection, tool knocking, and inability to center the tool in traditional machining methods, thus improving product quality. Simultaneously, by rationally arranging the machining process route, it reduces auxiliary time during machining, effectively improving machining efficiency. This invention is applicable to the machining of starter valve holes and starter valve intake holes in cylinder heads of various engine models. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the starter valve port and starter valve intake port on the cylinder head of a marine diesel engine.

[0026] Figure 2 yes Figure 1 AA sectional view.

[0027] Figure 3 This is a schematic diagram of the X92B type starter valve port and starter valve air inlet port.

[0028] Figure 4 yes Figure 3 BB cross-sectional view.

[0029] Figure 5 yes Figure 3 CC section view.

[0030] Figure 6 This is a schematic diagram of the method steps of the present invention.

[0031] In the picture,

[0032] 1—Starter valve hole, 2—Starter valve inlet hole, 3—Step hole, 41—First inclined hole, 42—Second inclined hole, 5—Through hole. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are not intended to limit the scope of the present invention.

[0034] This invention is used for machining the starter valve hole and starter valve intake hole in the cylinder head of a marine diesel engine.

[0035] Example

[0036] Please refer to the following: Figure 3 , Figure 4 and Figure 5 The starter valve hole 1 of the X92B model main engine cylinder head is a stepped through hole that penetrates the cylinder head, with a stepped hole 3 with a diameter of 140mm in the middle section; the starter valve inlet hole 2 is formed by the parallel intersecting first oblique hole 41 and second oblique hole 42 connected to the through hole 5. The diameter of the through hole 5 is 80mm, and its outer end opens on the surface of the cylinder head. The diameter of the first oblique hole 41 and the second oblique hole 42 is 64mm, the depth is 383mm, the surface finish requirement is Ra3.2, the axes intersect at 12°, and the center distance between the starting points is 16mm. The inner ends of the first oblique hole 41 and the second oblique hole 42 are simultaneously connected to the stepped hole 3 with a diameter of 140mm in the starter valve hole 1.

[0037] The specific processing steps are as follows:

[0038] Step 1: Machining the starter valve hole 1;

[0039] First, a 79mm diameter indexable insert drill bit is used to pre-drill the minimum diameter pre-drilled hole using a spiral milling tool. The tool length must be sufficient to drill through the starting valve hole 1. Then, a 63mm diameter high-feed end mill with a mandrel-type vibration damping rod is used to rough-machine the remaining stepped holes in the starting valve hole 1 along a spiral trajectory. At the same time, the chamfers inside the holes are also machined using a low-step spiral milling method. After rough machining, the starting valve hole 1 is finished using single boring and double boring methods to meet the drawing requirements.

[0040] Step 2: Pre-drill a through hole 5 with a diameter of 80mm;

[0041] First, a 79mm diameter indexable insert drill bit is used to pre-drill through hole 5, and at the same time, cross holes are made to avoid tool interference. Then, the hole opening is chamfered to complete the rough machining of through hole 5.

[0042] Step 3: Pre-machine the first inclined hole 41;

[0043] Please see Figure 6 The workpiece is rotated to a 6° position so that the axis of the tool is at the same angle as the axis of the first inclined hole 41. First, a 32mm diameter spiral end mill is used to mill a plane at the bottom of the pre-drilled hole of the through hole 5 that can be machined by the drill bit. A pre-drilled hole with a diameter of 26.5mm and a depth of 370mm is pre-machined at the position of the first inclined hole 41. This pre-drilled hole is to avoid the minimum machining diameter of the subsequent spiral end mill. After the pre-drilled hole of the first inclined hole 41 is completed, the workpiece is rotated back to the 0° position.

[0044] Step 4: Pre-machine the second inclined hole 42;

[0045] Please see Figure 6 The workpiece is rotated to a -6° position so that the tool axis is at the same angle as the axis of the second inclined hole 42. First, a 32mm diameter spiral end mill is used to mill a plane at the bottom of the pre-drilled hole of the through hole 5 that can be machined by the drill bit. A pre-drilled hole with a diameter of 26.5mm and a depth of 370mm is pre-machined at the position of the second inclined hole 42. This pre-drilled hole is to avoid the minimum machining diameter of the subsequent spiral end mill.

[0046] Step 5: Rough machining of the second inclined hole 42;

[0047] Please see Figure 6 Using a 50mm diameter high-speed milling cutter with a mandrel-type vibration damping rod, the cutter is started at a non-interference position of the second inclined hole 42. The second inclined hole 42 is roughed by spiral milling according to the spiral trajectory to a diameter of 63mm and a depth of 383mm, with a 0.5mm allowance in the diameter to facilitate subsequent finishing.

[0048] Step 6: Rough machining of the first inclined hole 41;

[0049] Please see Figure 6 The workpiece is rotated back to the 6° position so that the axis of the tool is at the same angle as the axis of the first inclined hole 41. A 50mm diameter high-speed milling cutter with a mandrel-type vibration damping rod is used to start the cutting at a non-interference position of the first inclined hole 41. The first inclined hole 41 is roughed by spiral milling according to the spiral trajectory to a diameter of 63mm and a depth of 383mm, with a 0.5mm allowance in the diameter for subsequent finishing.

[0050] Step 7: Finish machining the first oblique hole 41, the second oblique hole 42, and the through hole 5 with a diameter of 80mm;

[0051] Using a double boring tool with a mandrel-type vibration damping rod, the first oblique hole 41 and the second oblique hole 42 are semi-finish bored, leaving a radius allowance of 0.3-0.4mm. Then, using a single boring tool with a damping anti-vibration rod, the first oblique hole 41 and the second oblique hole 42 are finish bored to meet the Ra3.2 surface finish requirement of the drawing. The through hole 5 is then finish machined using the same single and double boring methods to meet the drawing requirements.

[0052] The machining method in this embodiment solves the problems of tool deflection, tool knocking, and inability to center the tool that exist in traditional machining methods, so that the machining results meet the requirements of the drawings and the machining process is stable.

[0053] This invention is applicable to the machining of the cylinder head starter valve hole and starter valve intake hole for all current engine models.

[0054] The above description is only the preferred embodiment of the present invention, but the scope of protection claimed by the present invention is not limited to the above embodiments. Any obvious equivalent transformations and alternatives that can be obtained by those skilled in the art within the technical scope disclosed in the present invention without creative labor are all within the scope of the present invention.

Claims

1. A method for machining a starter valve hole and a starter valve inlet hole in a marine diesel engine cylinder head, wherein the starter valve hole is a stepped through-hole penetrating the cylinder head, with a stepped hole in the middle section, and the starter valve inlet hole is formed by parallel intersecting first and second oblique holes connected to the through-hole, the through-hole opening onto the surface of the cylinder head, the axes of the first and second oblique holes intersecting at 12°, and their inner ends simultaneously penetrating the stepped hole; characterized in that: The processing method includes the following steps: Step 1: Machining the starter valve hole First, a small-diameter indexable insert drill bit is used to pre-drill the minimum diameter through pre-drilled hole for spiral milling. Then, a high-feed milling cutter with an indexable insert and a mandrel-type vibration damping rod is used to rough-machine the remaining stepped holes in the starter valve hole according to the spiral trajectory. After that, the starter valve hole is finished by single boring and double boring to meet the drawing requirements. Step 2: Rough machining of through holes The through hole is pre-drilled using an indexable insert drill bit, leaving a margin, and then the hole opening is chamfered to complete the rough machining of the through hole; Step 3: Pre-machine the first inclined hole Rotate the workpiece to a 6° position so that the tool axis is at the same angle as the axis of the first inclined hole. First, use a small diameter spiral milling cutter to mill a flat surface at the bottom of the pre-made hole of the through hole. Then, drill the minimum diameter pre-made hole for spiral milling at the position of the first inclined hole, thereby completing the machining of the pre-made hole of the first inclined hole. Step 4: Pre-machine the second inclined hole Rotate the workpiece to a -6° position so that the tool axis is at the same angle as the axis of the second inclined hole. First, use a small diameter spiral milling cutter to mill a flat surface at the bottom of the pre-made hole of the through hole. Then, drill the minimum diameter pre-made hole for spiral milling at the position of the second inclined hole, thereby completing the machining of the pre-made hole of the second inclined hole. Step 5: Rough machining of the second inclined hole Using a high-speed milling cutter with a mandrel-type vibration damping rod, the cutter is started at a non-interference position in the second inclined hole. The machining method is helical milling, and the second inclined hole is roughed along the helical trajectory, leaving a diameter allowance of 0.5mm to facilitate subsequent finishing. Step 6: Rough machining of the first inclined hole The workpiece is rotated back to the 6° position so that the tool axis is at the same angle as the axis of the first inclined hole. A high-speed milling cutter with a mandrel-type vibration damping rod is used to start the cutter at a non-interference position of the first inclined hole. The first inclined hole is roughed by using a spiral milling method and following the spiral trajectory. A diameter allowance of 0.5 mm is left to facilitate subsequent finishing. Step 7: Finish machining of the first inclined hole, the second inclined hole, and the through hole. Using a double boring tool with a mandrel-type vibration damping rod, the first and second inclined holes are semi-finish bored, leaving a radius allowance of 0.3-0.4mm. Then, using a single boring tool with a damping anti-vibration rod, the first and second inclined holes are finely bored to meet the drawing requirements. The through holes are then precision machined using the same single and double boring methods to meet the drawing requirements.

2. The machining method for the starter valve hole and starter valve inlet hole in the cylinder head of a marine diesel engine according to claim 1, characterized in that: In step one, the chamfer inside the starting valve hole is machined using a low-pitch spiral milling method.

3. The machining method for the starter valve hole and starter valve inlet hole in the cylinder head of a marine diesel engine according to claim 1, characterized in that: In step seven, the drawings for the first and second oblique holes are required to have a surface finish of Ra3.2.

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