Machining method for Y-hole of cylinder cover of low-speed machine for dual-fuel ship

Abstract

According to the machining method for the triple hole of the cylinder cover of the low-speed machine for the dual-fuel ship, a methanol valve hole of the cylinder cover is composed of a main valve hole, a left air inlet hole, a middle air inlet hole, a right air inlet hole, an inner air inlet hole, a middle air inlet hole and an outer air inlet hole, and the machining method comprises the following steps that firstly, the middle air inlet hole, the inner air inlet hole, the middle air inlet hole and the outer air inlet hole are machined; secondly, fixing screw holes are machined; step 3, processing a filler rod; 4, a filling rod is installed; fifthly, a left air inlet hole is machined; sixthly, the filler rod is dismantled; and seventhly, the filler rod is replaced, the fourth step, the fifth step and the sixth step are repeated, and machining of the right air inlet hole is completed. The machining method solves the problem that a conventional machining method cannot machine deep holes which are crossed in a three-fork mode and provided with greatly-broken sections, cutter knocking and cutter relieving are avoided, and machining of the three-fork air inlet hole with the included angle of 7 degrees of the methanol valve hole of the cylinder cover of the low-speed machine for the dual-fuel ship meets the technical requirement.

Description

Technical Field

[0001] The present invention relates to a processing technology for parts of a large dual-fuel marine diesel engine, and particularly to a processing method for a triple-hole of a cylinder head of a dual-fuel marine low-speed engine, belonging to the technical field of marine diesel engine processing. Background Art

[0002] The gas valve hole is a key part of the cylinder head of a large dual-fuel marine diesel engine. The traditional structure of the gas valve hole of the cylinder head of a large dual-fuel marine diesel engine is shown in Figure 1 . The intake of gas is connected to the gas valve through an outer pipe, and the gas valve is installed in the gas valve hole of the cylinder head. The structure of the gas valve hole of this design is simple, and the processing is also very simple, and it can be directly processed by conventional drills, boring mills and milling cutters.

[0003] However, the gas valve hole of the cylinder head of the large dual-fuel marine low-speed engine described in the present invention is changed to a methanol valve hole, which adopts a relatively special structure. Taking the 10X92DF-M type main engine as an example, please refer to Figure 2 , Figure 3 , Figure 4 and Figure 5 . The methanol valve hole of the cylinder head is composed of a main valve hole D1, a triple intake hole and an outer intake hole. The main valve hole D1 leads downward from the top surface of the cylinder head to the cylinder inner cavity, and the axis of the triple intake hole is horizontally communicated with the main valve hole D1, see Figure 3 , forming a 75° angle with the main valve hole D1; the triple intake hole is composed of a left intake hole D2, a middle intake hole D3 and a right intake hole D4, and the three holes are distributed in a three-axis cross pattern, and the hole walls intersect to form a break shape, see Figure 5 , wherein the left intake hole D2 and the right intake hole D4 respectively form an angle C1 of 7° with the middle intake hole D3 on both sides, see Figure 2 . The left intake hole D2, the middle intake hole D3 and the right intake hole D4 have the same diameter of 20 mm, a depth > 320 mm, and a surface roughness requirement of Ra6.3. The outer intake hole is communicated with the triple intake hole, and the outer end opens on the side surface of the cylinder head. The outer intake hole is on the same level as the triple intake hole and forms a 75° angle with the main valve hole D1; the outer intake hole is a stepped hole, which is composed of an inner intake hole D5, a middle intake hole D6 and an outer intake hole D7 connected in sequence from the inside to the outside, see Figure 3 , and the hole diameters increase in sequence.

[0004] Since the angles between the left intake hole D2, the middle intake hole D3 and the right intake hole D4 are small, the cross section thereof becomes an incomplete circle with three adjacent breaks. Please refer to Figure 5During direct machining, serious tool deflection and chattering occur; moreover, since the diameters of the inner air inlet hole D5, middle air inlet hole D6, and outer air inlet hole D7 on its outer side are not large, and the overall depth is greater than 320 mm, it causes interference with the machine tool spindle. Therefore, the tool needs to be lengthened, resulting in the tool length-diameter ratio of the machining tool exceeding 10 times the diameter. As a result, its machining is much more difficult compared to the gas valve hole of the traditional structure, and it is difficult to complete the machining using conventional drilling, boring, and milling methods. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a machining method for the three-way holes of the cylinder head of a dual-fuel marine low-speed engine to solve the problem of difficult machining of the air inlet holes of the methanol valve hole of the cylinder head of a large dual-fuel marine diesel engine. By scientifically arranging the cutting sequence, designing the tooling, and reasonably using the tools, the technical problem that the conventional machining method cannot machine the deep holes in the form of three-way holes is solved, and the machining of the air inlet holes of the methanol valve hole meets the requirements.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0007] A machining method for the three-way holes of the cylinder head of a dual-fuel marine low-speed engine, wherein the methanol valve hole of the cylinder head is composed of a main valve hole with a vertical axis, a three-way air inlet hole with a horizontal axis, and an outer air inlet hole. The three-way air inlet hole and the outer air inlet hole communicate with the main valve hole and form a 75° angle. The three-way air inlet hole is composed of a left air inlet hole, a middle air inlet hole, and a right air inlet hole with the same diameter of 20 mm, and the depth > 320 mm. The left air inlet hole, the middle air inlet hole, and the right air inlet hole are distributed in a three-axis cross pattern, and the cross-sections of the hole walls are connected to form an incomplete circle with three breaks. Among them, the left air inlet hole and the right air inlet hole form a 7° angle with the middle air inlet hole on both sides respectively. The outer air inlet hole is a stepped hole, which is composed of an inner air inlet hole, a middle air inlet hole, and an outer air inlet hole connected in sequence from the inside to the outside, and the hole diameters increase in sequence. The characteristics of the machining method are as follows:

[0008] Step 1, machine the middle air inlet hole of the three-way air inlet hole, the inner air inlet hole, the middle air inlet hole, and the outer air inlet hole of the outer air inlet hole;

[0009] Step 2, machine fixing screw holes on the bottom surface of the outer air inlet hole;

[0010] Step 3, machine a packing rod from a material similar to the cylinder head. The packing rod includes a small shaft, a middle shaft, a large shaft, and a flange surface connected coaxially. The diameters of the small shaft, the middle shaft, and the large shaft increase in sequence and are in clearance fit with the machined middle air inlet hole, inner air inlet hole, and middle air inlet hole respectively. Fixing through holes matching the fixing screw holes are machined on the flange surface;

[0011] Step 4, fix the packing rod in the middle air inlet hole, inner air inlet hole, and middle air inlet hole through screws;

[0012] Step 5: With the middle air inlet hole as the reference, turn the workpiece by an angle of 7°. First, mill a counterbore on the end face of the packing rod, then pre-drill a shallow hole with a diameter of 20 mm, and then use a Φ20 gun drill to drill through inward to the main valve hole to complete the machining of the left air inlet hole;

[0013] Step 6: Remove the processed incomplete packing rod;

[0014] Step 7: Replace with another identical packing rod, repeat Step 4, Step 5 and Step 6 to complete the machining of the right air inlet hole, thereby completing the machining of the three-way hole.

[0015] Furthermore, the surface roughness requirements for the left air inlet hole, the middle air inlet hole and the right air inlet hole are Ra6.3.

[0016] Furthermore, in Step 5, the diameter of the counterbore is slightly larger than the diameter of the left air inlet hole.

[0017] Furthermore, in Step 5, the machining of the left air inlet hole is carried out by straddle machining on the entity formed by the packing rod and the cylinder head.

[0018] The present invention solves the difficulty of machining deep holes with three-way intersections and large cross-section breaks by conventional machining methods, avoids the occurrence of tool knocking and tool deflection, and enables the machining of the three-way air inlet holes with a 7° angle in the methanol valve hole of the cylinder head of a dual-fuel marine low-speed engine to meet the technical requirements. Description of the Drawings

[0019] Figure 1 is a schematic diagram of a traditional gas valve hole.

[0020] Figure 2 is a schematic diagram of the three-way hole of the cylinder head of the dual-fuel marine low-speed engine of the present invention.

[0021] Figure 3 is Figure 2 the A-A cross-sectional view of.

[0022] Figure 4 is the B-B cross-sectional view in the A-A section.

[0023] Figure 5 is Figure 4 the enlarged view of part C of.

[0024] Figure 6 is the structural schematic diagram of the packing rod.

[0025] Figure 7 is the schematic diagram of the processing flow of the present invention.

[0026] Figure 8It is a schematic diagram of the fourth processing step of the present invention.

[0027] Figure 9 It is a schematic diagram of the fifth processing step of the present invention.

[0028] In the figure,

[0029] D1 - main valve hole, D2 - left intake hole, D3 - middle intake hole, D4 - right intake hole, D5 - inner intake hole, D6 - middle intake hole, D7 - outer intake hole, D8 - small shaft, D9 - middle shaft, D10 - large shaft, D11 - flange surface, D12 - packing rod, D13 - screw, D14 - fixed screw hole, D15 - fixed through hole. Specific embodiments

[0030] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, so that the technical solutions of the present invention can be more easily understood by those skilled in the art, but the protection scope of the present invention cannot be limited thereby.

[0031] Embodiment

[0032] Taking the machining of the intake triple hole of the methanol valve hole of the 10X92DF - M type main engine cylinder head as an example, please refer to Figure 2 , Figure 3 , Figure 4 and Figure 5 , the methanol valve hole is composed of a main valve hole D1, a triple intake hole and an outer intake hole. The triple intake hole with a horizontal axis is connected to the main valve hole D1 with a vertical axis and forms an angle of 75°, and the diameter of the main valve hole D1 at the connection is 182 mm. The triple intake hole is composed of a left intake hole D2, a middle intake hole D3 and a right intake hole D4. The three holes are distributed in a three - axis cross - type, and the cross - section of the hole wall is connected to form an incomplete circle with three breaks, as shown in Figure 5 , where the left intake hole D2 and the right intake hole D4 form an angle C1 of 7° with the middle intake hole D3 on both sides respectively, as shown in Figure 2 . The left intake hole D2, the middle intake hole D3 and the right intake hole D4 have the same diameter of 20 mm, a depth > 320 mm, and the surface roughness requirement is Ra6.3. The outer intake hole is connected to the triple intake hole and is on the same horizontal plane. The outer intake hole is a stepped hole, which is composed of an inner intake hole D5, a middle intake hole D6 and an outer intake hole D7 connected in sequence from inside to outside, as shown in Figure 3 , and the hole diameters increase in sequence.

[0033] The processing method of the triple hole of the cylinder head of the dual - fuel marine low - speed engine of the present invention specifically includes the following steps:

[0034] Step 1, after machining the main valve hole D1, machine the middle intake hole D3 of the three-way intake hole, the inner intake hole D5 of the outer intake hole, the middle intake hole D6, and the outer intake hole D7;

[0035] Step 2, machine the fixing screw holes:

[0036] Refer to Figure 2 , and machine 2 fixing screw holes D14 on the bottom surface of the outer intake hole D7;

[0037] Step 3, machine the packing rod:

[0038] Take a material similar to the cylinder head body, refer to Figure 6 , and machine it into a stepped packing rod D12. The packing rod D12 includes a small shaft D8, a middle shaft D9, a large shaft D10, and a flange surface D11 that are coaxially connected from left to right. The diameters of the small shaft D8, the middle shaft D9, and the large shaft D10 increase in sequence and form a clearance fit with the middle intake hole D3, the inner intake hole D5, and the middle intake hole D6 that have been machined on the cylinder head respectively. 2 fixing through holes D15 are machined on the flange surface D11, and the positions are matched with the fixing screw holes D14;

[0039] Step 4, install the packing rod:

[0040] Refer to Figure 8 , insert the packing rod D12 into the middle intake hole D3, the inner intake hole D5, and the middle intake hole D6, align the 2 fixing through holes D15 on its flange surface D11 with the 2 fixing screw holes D14 on the bottom surface of the outer intake hole D7, and screw in and tighten the screws D13;

[0041] Step 5, machine the left intake hole:

[0042] Refer to Figure 9 , take the middle intake hole D3 as the reference, turn the workpiece by 7° with the same angle as the included angle C1, use a milling cutter to machine a counterbore on the end face of the packing rod D12 with a diameter slightly larger than the left intake hole D2 to create conditions for the subsequent centering of the drill bit, then use a short Φ20 drill bit to pre-drill a shallow hole, and then use a 20 mm diameter gun drill to drill through the entity formed by the packing rod D12 and the cylinder head inward in a straddle manner to the main valve hole D1 to complete the machining of the left intake hole D2;

[0043] Step 6, remove the packing rod:

[0044] Remove the screw D13 and extract the processed and incomplete packing rod D12;

[0045] Step 7, replace it with another identical new packing rod D12, repeat Step 4, Step 5, and Step 6 to complete the machining of the right intake hole D4, thereby completing the machining of the three-way hole.

[0046] The processing method of the triple-hole of the cylinder head of the dual-fuel marine low-speed engine described in the present invention solves the difficulty of processing the triple-deep hole of the cylinder head with triple intersections and large-section breakages by conventional processing methods, avoids the occurrence of tool knocking and tool yielding, and enables the processing of the intake triple-hole of the methanol valve hole to meet the requirements of the drawing.

[0047] The above is only the best embodiment of the present invention, but the scope of protection required by the present invention is not limited to the above embodiments. Any obvious equivalent transformations and alternative solutions that can be obtained by those skilled in the art without creative labor within the technical scope disclosed by the present invention shall fall within the scope of the present invention.

Claims

1. A processing method for the triple-hole of the cylinder head of a dual-fuel marine low-speed engine. The methanol valve hole of the cylinder head is composed of a main valve hole with a vertical axis, a triple-inlet hole with a horizontal axis, and an outer inlet hole. The triple-inlet hole and the outer inlet hole are communicated with the main valve hole and form a 75° angle. The triple-inlet hole is composed of a left inlet hole, a middle inlet hole, and a right inlet hole with the same diameter of 20 mm and a depth > 320 mm. The left inlet hole, the middle inlet hole, and the right inlet hole are distributed in a three-axis cross pattern, and the cross-sections of the hole walls are connected to form an incomplete circle with three breaks. The left inlet hole and the right inlet hole form a 7° angle with the middle inlet hole on both sides respectively. The outer inlet hole is a stepped hole, which is composed of an inner inlet hole, a middle inlet hole, and an outer inlet hole connected in sequence from inside to outside, and the hole diameters increase in sequence. The characteristics are as follows: The described processing method includes the following steps: Step 1, process the middle intake hole of the three-way intake hole, the inner intake hole, the middle intake hole and the outer intake hole of the outer intake hole; Step 2, process the fixing screw holes on the bottom surface of the outer intake hole; Step 3, machine a packing rod from a material similar to the cylinder head. The packing rod includes a small shaft, a middle shaft, a large shaft and a flange surface connected coaxially. The diameters of the small shaft, the middle shaft and the large shaft increase in sequence and are in clearance fit with the processed middle intake hole, inner intake hole and middle intake hole respectively. Fixing through holes matching the fixing screw holes in position are machined on the flange surface; Step 4, fix the packing rod in the middle intake hole, inner intake hole and middle intake hole with screws; Step 5, with the middle intake hole as the reference, turn the workpiece by an angle of 7°. First, mill a counterbore on the end face of the packing rod, then pre-drill a shallow hole with a diameter of 20 mm, and then use a Φ20 gun drill to drill through inward to the main valve hole to complete the processing of the left intake hole; Step 6, remove the processed incomplete packing rod; Step 7, replace it with another identical packing rod, repeat Step 4, Step 5 and Step 6 to complete the processing of the right intake hole, thereby completing the processing of the three-way hole.

2. The machining method of the triple-hole of the cylinder head of the dual-fuel marine low-speed engine according to claim 1, characterized in that: The surface roughness requirements for the left intake hole, middle intake hole and right intake hole are Ra6.

3.

3. The machining method of the triple-hole on the cylinder head of the dual-fuel marine low-speed engine according to claim 1, characterized in that: In the described Step 5, the diameter of the counterbore is slightly larger than the diameter of the left intake hole.

4. The machining method of the triple-hole of the cylinder head of the dual-fuel marine low-speed engine according to claim 1, characterized in that: In the described Step 5, the processing of the left intake hole is carried out as a split-hole machining on the entity formed by the packing rod and the cylinder head.

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