Grinding tool and grinding method for grinding inner bore of hard and brittle tube having large length-to-diameter ratio
By combining segmented grinding tools with cooling/grinding fluid, the problem of difficult precision machining of the inner hole of ceramic pipes with large length-to-diameter ratio is solved, achieving efficient and low-damage inner hole machining results.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2025-03-05
- Publication Date
- 2026-05-21
AI Technical Summary
Ceramic pipes with large length-to-diameter ratios are prone to damage during the machining of their inner holes and are difficult to precision machine, becoming a pain point restricting my country's energy development.
The segmented grinding tool is divided into a guide section, a tapered section, and a sizing section. Combined with the design of an annular grinding head and annular groove, the guide section passes through and rotates, and the reciprocating motion is combined with the hole enlargement of the tapered section and the sizing section for sizing. With the injection of coolant and grinding fluid, the inner hole of hard and brittle pipe fittings can be finely machined.
It reduces resistance during the grinding process, prevents jamming, improves machining accuracy and coaxiality, reduces scratches on the inner wall caused by grinding debris, and ensures efficient precision machining of hard and brittle pipe fittings.
Smart Images
Figure CN2025080715_21052026_PF_FP_ABST
Abstract
Description
A grinding tool and grinding method for grinding the inner bore of hard and brittle pipe fittings with a large length-to-diameter ratio. Technical Field
[0001] This invention belongs to the field of hard and brittle material processing, and particularly relates to a grinding tool and grinding method for grinding the inner hole of hard and brittle pipes with a large length-to-diameter ratio. Background Technology
[0002] Ceramic tubes possess excellent physicochemical properties and are widely used in semiconductor, nuclear energy, and aerospace fields. For example, silicon carbide ceramic tubes are used as inner linings in nuclear energy, and silicon carbide tubes are used as heat exchange tubes in the semiconductor field. These tubes are typically over 1000mm in length and have an inner diameter of 7-8mm. They not only possess high hardness and brittleness but also feature a very large aspect ratio and thin wall thickness. This makes the large aspect ratio of ceramic tubes prone to damage during internal bore machining, and it is difficult to perform precision machining on the inner wall. This makes the machining of these parts a bottleneck restricting my country's energy development. Summary of the Invention
[0003] In view of this, the present invention provides a grinding tool and grinding method for grinding the inner hole of hard and brittle pipes with a large length-to-diameter ratio. The segmented grinding tool reduces the resistance to the movement of the grinding tool and the inner wall of the pipe, thereby realizing the processing of hard and brittle pipes with a large length-to-diameter ratio.
[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:
[0005] A grinding tool for grinding the inner hole of hard and brittle pipe fittings with a large length-to-diameter ratio is a grinding tool with a large length-to-diameter ratio consisting of annular grinding heads and annular grooves arranged alternately. Along the length direction of the grinding tool, it is divided into three sections: a guide section, a tapered section, and a sizing section. The guide section is used to penetrate the inner hole of the hard and brittle pipe fitting, the tapered section is used for grinding and enlarging the inner hole of the hard and brittle pipe fitting, and the sizing section is used for sizing grinding the inner hole of the hard and brittle pipe fitting.
[0006] The grinding tool passes through the inner hole of the hard and brittle pipe through the guide section and is straightened. The grinding tool rotates, and the hard and brittle pipe moves from the guide section to the sizing section while also reciprocating until the hard and brittle pipe moves to the sizing section and is ground, so as to realize the processing of the inner hole of the hard and brittle pipe.
[0007] Preferably, the length ratio of the guide section, the tapered section, and the sizing section is 1:3:1 to 1:4:1; the length ratio of the rigid and brittle pipe fitting to the guide section is 5:6.
[0008] Preferably, the annular grinding head of the guide section is a guide grinding head of equal diameter.
[0009] Preferably, the annular grinding head of the tapered section is a tapered enlarged diameter grinding head, and the outer diameter of the enlarged diameter grinding head gradually increases along the forward direction of the hard and brittle pipe.
[0010] Preferably, the annular grinding head in the sizing section is a sizing grinding head of equal diameter.
[0011] Preferably, the grinding tool has a liquid injection channel along its length, and a drain hole through the liquid injection channel is opened at the annular groove. Grinding liquid or coolant is injected into the liquid injection channel, and the grinding liquid or coolant is thrown to the annular groove to achieve cooling or grinding of the inner hole of the hard and brittle pipe.
[0012] Preferably, diamond micropowder is electroplated on the surface of the annular grinding head to make it a roughing grinding tool; or the surface of the annular grinding head is textured to make it a finishing grinding tool.
[0013] A method for grinding the inner hole of hard and brittle pipe fittings with a large length-to-diameter ratio, the specific process of which is as follows:
[0014] S1, determine the number of machining operations for the hard and brittle pipe fitting, the number of grinding tools, and the outer diameter of each grinding tool:
[0015] Let the target size of the inner bore of the brittle pipe be D. n The actual minimum inner diameter of the inner bore of a hard and brittle pipe fitting is D. nmin The single grinding amount Δd of the hard and brittle pipe fitting and the taper difference Δa of the taper section of the grinding tool, the number of grinding tools is m; the number of processing times n for the hard and brittle pipe fitting is expressed as:
[0016] The diameter D of the sizing grinding head of the i-th grinding tool i+1 Satisfy the following relationship: D i+1 =Δd+D i ,i∈(0,n)
[0017] The diameter D' of the guide grinding head of the i-th grinding tool satisfies the following relationship: D' = D i+1 -Δa,i∈(0,n)
[0018] S2, according to the number of times the hard and brittle pipe is processed, the inner hole of the hard and brittle pipe is processed in sequence according to the grinding tools from the 1st to the mth pipe;
[0019] S21 Roughing stage: The roughing grinding tool penetrates the inner hole of the hard and brittle pipe and straightens it. While the roughing grinding tool rotates, coolant is kept between the annular groove and the inner wall of the hard and brittle pipe. The hard and brittle pipe moves from the guide section to the sizing section and also moves back and forth until the hard and brittle pipe moves to the sizing section and is ground, so as to achieve roughing of the inner hole of the hard and brittle pipe.
[0020] S22, Finishing stage: The finishing grinding tool penetrates the inner hole of the hard and brittle pipe and straightens it. While the finishing grinding tool rotates, it keeps the grinding fluid between the annular groove and the inner wall of the hard and brittle pipe. The hard and brittle pipe moves from the guide section to the sizing section and also moves back and forth until the hard and brittle pipe moves to the sizing section and is ground, so as to achieve the finishing of the inner hole of the hard and brittle pipe.
[0021] Preferably, in step S1, free-falling coolant is provided on both sides of the roughing grinding tool, and the coolant is drawn into the annular groove of the roughing grinding tool. The hard and brittle tube moves forward to ensure that there is coolant between the annular groove and the inner wall of the hard and brittle tube. In step S2, free-falling polishing fluid is provided on both sides of the finishing grinding tool, and the polishing fluid is drawn into the annular groove of the finishing grinding tool. The hard and brittle tube moves forward to ensure that there is polishing fluid between the annular groove and the inner wall of the hard and brittle tube.
[0022] Preferably, the roughing grinding tool has a liquid injection channel along its length, and a drain hole penetrating the liquid injection channel is opened at the annular groove. Coolant is injected into the liquid injection channel and is thrown to the annular groove to ensure that there is coolant between the annular groove and the inner wall of the hard and brittle pipe. The finishing grinding tool has a liquid injection channel along its length, and a drain hole penetrating the liquid injection channel is opened at the annular groove. Grinding fluid is injected into the liquid injection channel and is thrown to the annular groove to ensure that there is polishing fluid between the annular groove and the inner wall of the hard and brittle pipe.
[0023] The beneficial effects of this invention compared to the prior art are:
[0024] 1. The grinding tool adopts a segmented structure. During the machining of the inner hole of hard and brittle pipes, only the grinding head part contacts the inner wall of the workpiece to achieve the machining of the inner hole. The annular groove part can effectively reduce the contact area between the grinding tool and the inside of the pipe, thereby reducing the resistance during the grinding process and preventing the pipe with a large length-to-diameter ratio from getting stuck with the grinding tool during the grinding process.
[0025] 2. During the machining process, an annular cavity is formed between the annular groove and the inner wall of the workpiece, which can effectively store coolant or grinding fluid. If the annular cavity stores coolant, it can cool the workpiece's inner hole during machining. If the annular cavity stores grinding fluid, the grinding fluid will swirl within the annular cavity during the rotation of the grinding tool, which can, to some extent, grind the inner wall of the fitting, improving the workpiece's machining accuracy. Furthermore, the grinding debris generated during the grinding process can be stored in the coolant or grinding fluid, preventing the debris from scratching the inner wall of the workpiece's inner hole and affecting its machining accuracy. During the reciprocating movement of the workpiece, the grinding fluid or coolant will flow out to clean up the grinding debris.
[0026] 3. Due to the high hardness and brittleness of hard and brittle pipe fittings, during the rotation of the grinding tool and the large-span reciprocating movement of the workpiece, a tapered reaming head can be used to achieve progressive reaming, reducing the probability of damage to the hard and brittle pipe fittings. After reaming, repeated grinding with a sizing head can further ensure the coaxiality of the inner hole of the pipe fitting.
[0027] 4. The length ratio of the guide section, taper section and sizing section of the grinding tool is 1:3:1 to 1:4:1, and the length ratio of the workpiece to the guide section is 5:6. This ensures a reasonable length ratio between the workpiece and the tool, enabling the finishing of the workpiece, without causing the tool to be too long, which would be detrimental to rotation and support.
[0028] 5. This invention can employ two methods to ensure the uniform distribution of coolant and polishing fluid in the grinding area. One method involves creating a fluid injection channel within the grinding tool. Coolant or polishing fluid is then pumped into this channel, ensuring uniform distribution across the grinding area and guaranteeing the grinding quality of the workpiece's inner hole. Since the grinding tool is relatively long, some polishing fluid or coolant may overflow. The drain holes in the un-grinded portions can be plugged, and the opening position of the drain holes can be manually controlled as the grinding process progresses. The other method involves placing free-falling coolant / polishing fluid on both sides of the grinding tool. Based on Bernoulli's principle, a negative pressure is created on the surface of the grinding tool during rotation, drawing the coolant or polishing fluid into the annular groove. As the hard, brittle tube moves forward, it covers the grinding tool, which is coated with coolant or polishing fluid, ensuring that the space between the annular groove and the inner wall of the hard, brittle tube contains coolant / polishing fluid. Attached Figure Description
[0029] The accompanying drawings, which form part of this application, are provided to further illustrate the invention.
[0030] Figure 1 is a schematic diagram of the roughing and grinding tool of the present invention.
[0031] Figure 2 is a schematic diagram of the structure of the finishing grinding tool of the present invention.
[0032] Figure 3 shows the processing method in Example 3 where a liquid spraying method is used to maintain coolant or grinding fluid between the annular groove and the inner wall of the hard and brittle pipe.
[0033] Figure 4 shows the processing method in Example 2 where a pump is used to maintain coolant or grinding fluid between the annular groove and the inner wall of the hard and brittle pipe.
[0034] Figure 5 shows the change in the outer diameter of the grinding tool from the 1st tool to the (n+1th tool).
[0035] Explanation of reference numerals in the attached drawings: 1-Guide section; 1-1-Guide grinding head; 2-Tapered section; 2-1-Expanding grinding head; 3-Sizing section; 3-1-Sizing grinding head; 4-Annular groove; 5-Hard and brittle pipe fitting; 6-Plug. Detailed Implementation
[0036] The invention will be described in detail below with reference to specific embodiments.
[0037] Example 1:
[0038] Referring to Figure 1, this application embodiment provides a grinding tool for grinding the inner hole of a hard and brittle pipe with a large length-to-diameter ratio. It is a segmented grinding tool with a large length-to-diameter ratio, consisting of alternating annular grinding heads and annular grooves 4. Along the length of the grinding tool, it is divided into three sections: a guide section 1 with gradually increasing outer diameter, a tapered section 2, and a sizing section 3. The guide section 1 is used to penetrate the inner hole of the hard and brittle pipe 5, and the annular grinding head of the guide section 1 is a guide grinding head 1-1 of equal diameter. The tapered section 2 is used for grinding and enlarging the inner hole of the hard and brittle pipe 5, and the annular grinding head of the tapered section 2 is an enlarging grinding head 2-1 with a tapered diameter, the outer diameter of the enlarging grinding head 2-1 gradually increasing along the forward direction of the hard and brittle pipe 5. The sizing section 3 is used for grinding the inner hole of the hard and brittle pipe 5, and the annular grinding head of the sizing section 3 is a sizing grinding head 3-1 of equal diameter. During the machining of the hard and brittle pipe fitting 5, the grinding tool passes through the guide section 1 into the inner hole of the hard and brittle pipe fitting 5 and is straightened. The grinding tool rotates, and the hard and brittle pipe fitting 5 moves along the length of the grinding tool from the guide section 1 towards the sizing section 3, while also reciprocating, until the hard and brittle pipe fitting 5 moves to the sizing section 3 and is ground, thereby achieving the machining of the inner hole of the hard and brittle pipe fitting 5. The length of the annular groove 4 and the annular grinding head is generally 20-40 mm, and the groove depth of the annular groove 4 is generally 0.4-0.6 mm.
[0039] In this embodiment, the grinding tool adopts a segmented structure. During the machining of the inner hole of the hard and brittle pipe 5, only the annular grinding head portion, such as the guide grinding head 1-1, the expanding grinding head 2-1, and the sizing grinding head 3-1, contacts the inner wall of the hard and brittle pipe 5 to achieve the machining of the inner hole. The annular groove 4 effectively reduces the contact area between the grinding tool and the inside of the pipe, thereby reducing the resistance during the grinding process and preventing the pipe with a large length-to-diameter ratio from jamming with the grinding tool during the grinding process. At the same time, during the machining process, an annular cavity is formed between the annular groove 4 and the inner wall of the hard and brittle pipe 5, which can effectively store coolant or grinding fluid. If the annular cavity stores coolant, it can cool the machining of the inner hole of the hard and brittle pipe 5. If the annular cavity stores grinding fluid, the grinding fluid will generate swirling flow in the annular cavity during the rotation of the grinding tool, which can produce a grinding effect on the inner wall of the pipe to a certain extent and improve the machining accuracy of the hard and brittle pipe 5. Furthermore, the abrasive shavings generated during the grinding process of the inner hole of the hard and brittle pipe 5 can be stored in the coolant or grinding fluid, preventing the shavings from scratching the inner wall of the inner hole and affecting the machining accuracy of the hard and brittle pipe 5. During the reciprocating movement of the hard and brittle pipe 5, the grinding fluid or coolant will flow out to clean the abrasive shavings. Due to the high hardness and brittleness of the hard and brittle pipe 5, a tapered reaming head 2-1 can be used to achieve progressive reaming during the rotation of the grinding tool and the reciprocating movement of the hard and brittle pipe 5. If the grinding tool is of uniform diameter, it is prone to damage to the hard and brittle pipe 5. After reaming, repeated grinding with the sizing head 3-1 can further ensure the coaxiality of the inner hole of the pipe.
[0040] Since the grinding tool grinds the inner hole of the hard and brittle pipe 5, it needs to be inserted into the inner hole of the hard and brittle pipe 5 for grinding. However, the hard and brittle pipe 5 has a large length-to-diameter ratio, with longer hard and brittle pipe 5s reaching about 4 meters. The inner diameter of the hard and brittle pipe 5 is approximately between 7.5 mm and 8.5 mm. At the same time, the inner hole of the hard and brittle pipe 5 needs to move back and forth significantly during the grinding process. This requires the length of the grinding tool to be at least 5 times the length of the hard and brittle pipe 5. The grinding tool is prone to bending at such a length and with a small outer diameter, which affects the surface processing of the hard and brittle pipe 5. Therefore, it needs to penetrate the inner hole of the hard and brittle pipe 5 and be straightened. The starting position of the hard and brittle pipe 5 before grinding is the guide section 1, so the length of the guide section 1 must be greater than the length of the hard and brittle pipe 5. The sizing section 3 is to ensure the coaxiality of the inner hole of the hard and brittle pipe 5, so the length of the sizing section 3 must also be greater than the length of the hard and brittle pipe 5. Therefore, in this embodiment, the length ratio of the guide section 1, the taper section 2, and the sizing section 3 is 1:3:1 to 1:4:1, and the length ratio of the hard and brittle pipe 5 to the guide section 1 is 5:6. This ensures a reasonable length ratio between the hard and brittle pipe 5 and the tool, enabling the finishing of the hard and brittle pipe 5 without causing the tool to be too long, which would be detrimental to rotation and support. If the ratio of these three parts of the grinding tool is too large, the processing tool will be extremely long. For example, if the length of the pipe to be processed is 1.2 meters, then the length of the sizing section 3 and the guide section 1 must be at least 1.2 meters, the length of the taper section must be at least 3 to 3.6 meters, and the total length of the grinding tool must be at least 5 meters. If the ratio of these three parts of the grinding tool is 1:1:1, the taper span of the taper section will be too large, making it impossible to grind the hard and brittle pipe 5. If the ratio is 1:5:1, the total length of the tool will be too large, which would be detrimental to rotation and support.
[0041] Because coolant or grinding fluid needs to be injected into the annular groove 4 of the grinding tool, but after the hard and brittle tube 5 is fitted onto the grinding tool, a nearly closed annular cavity is formed between the hard and brittle tube 5 and the annular groove 4, the coolant or grinding fluid cannot be injected from the outside. This makes it impossible to cool the hard and brittle tube 5 and the tool, and it is also not conducive to the discharge of grinding debris. Therefore, in this embodiment, a liquid injection channel is opened along the length direction inside the grinding tool. The inner diameter of the liquid injection channel is 2-4mm (since the inner diameter of the hard and brittle tube 5 is only 7.5mm-8.5mm). A drain hole is opened at the annular groove 4, which runs through the liquid injection channel. Grinding liquid or grinding liquid is injected into the liquid injection channel by pumping coolant or grinding liquid. The grinding liquid or coolant is thrown to the annular groove 4 so that the coolant and grinding liquid are evenly distributed in the grinding area, ensuring the grinding quality of the inner hole of the hard and brittle tube 5. Since the grinding tool is long, some grinding liquid or coolant may flow out. The drain hole of the part that is not involved in the grinding can be plugged with a plug 6. As the grinding process proceeds, the opening position of the drain hole is manually controlled. This embodiment offers another method for supplying coolant or polishing fluid: coolant / polishing fluid is freely disposed on both sides of the grinding tool. Based on Bernoulli's principle, a negative pressure is created on the surface of the grinding tool during rotation, drawing the coolant or polishing fluid into the annular groove 4. As the hard, brittle tube 5 moves forward, it covers the grinding tool, ensuring that the space between the annular groove 4 and the inner wall of the hard, brittle tube 5 contains coolant / polishing fluid. This method eliminates the need for injection channels or drilling within the grinding tool, thus maintaining its rigidity. It should also be noted that this embodiment does not use a spraying method to apply coolant or polishing fluid to the grinding tool, as this would create an impact force, affecting the tool's stability during the grinding process and consequently impacting the machining accuracy of the inner hole of the hard, brittle tube 5.
[0042] Since the inner hole of the hard and brittle pipe 5 needs to be processed in two stages—roughing and finishing—the grinding tools in this embodiment include two types. One type is a roughing tool for the roughing stage, in which diamond microparticles are electroplated on the surfaces of the guide grinding head 1-1, the expanding grinding head 2-1, and the sizing grinding head 3-1. The particle size of the abrasive grains is 5–10 μm, and the diameter of the taper section 2 changes by +0.05 mm / m from the guide section 1 to the sizing section 3. The other type is a finishing tool for the finishing stage, in which the surfaces of the guide grinding head 1-1, the expanding grinding head 2-1, and the sizing grinding head 3-1 are textured. The texture type is generally a cross-helix, with a helix width of approximately 1 mm and a depth of approximately 100 μm. The textured surface treatment of the finishing tool can improve the flow of grinding fluid and coolant. The diameter of the taper section 2 changes by +0.01 mm / m from the guide section 1 to the sizing section 3.
[0043] Example 2:
[0044] This embodiment provides a method for grinding the inner hole of hard and brittle pipes with a large length-to-diameter ratio. The method utilizes roughing and finishing grinding tools, and the grinding steps are as follows:
[0045] S1, determine the number of machining operations for the hard and brittle pipe fitting, the number of grinding tools, and the outer diameter of each grinding tool:
[0046] Let the target size of the inner bore of the brittle pipe be D. n The actual minimum diameter of the inner bore of a hard and brittle pipe fitting is D. nmin The single grinding depth Δd and the taper difference Δa (the diameter difference from the starting position to the ending position of the taper segment) of the hard and brittle pipe fitting are given. The number of grinding tools is m. To eliminate the initial dimensional error of the inner hole of the hard and brittle pipe fitting, the inner hole of the hard and brittle pipe fitting is usually pre-treated using the first grinding tool. The diameter of the sizing section of the first grinding tool is the minimum inner diameter D of the hard and brittle pipe fitting. nmin When the minimum inner diameter D of the hard and brittle pipe fitting is used nmin When hard and brittle pipe fittings cannot pass effectively during the sizing section of the grinding tool, the number of pre-treatment grinding cycles should be increased. Therefore, the number of processing cycles n for hard and brittle pipe fittings is expressed as:
[0047] The diameter of the sizing grinding head of the i-th grinding tool satisfies the following relationship: D i+1 =Δd+D i ,i∈(0,n)
[0048] The diameter of the guide grinding head of the i-th grinding tool satisfies the following relationship: D min =D i+1 -Δa,i∈(0,n)
[0049] S2, according to the number of times the hard and brittle pipe is processed, the inner hole of the hard and brittle pipe is processed in sequence according to the grinding tools from the 1st to the mth pipe;
[0050] S21, Rough machining stage: The guide section 1 of the rough machining grinding tool penetrates the inner hole of the hard and brittle pipe 5, straightens the rough machining grinding tool and supports it with a support device. The rough machining grinding tool rotates uniformly at a speed of 100 rpm / min. At the same time, free-falling coolant is provided on both sides of the rough machining grinding tool. The coolant is drawn into the annular groove 4 of the rough machining grinding tool. The hard and brittle pipe 5 moves forward to keep the coolant between the annular groove 4 and the inner wall of the hard and brittle pipe 5. The hard and brittle pipe 5 moves back and forth in a large span from the guide section 1 to the sizing section 3 along the length direction of the rough machining grinding tool until the hard and brittle pipe 5 moves to the sizing section 3 and is ground to achieve rough machining of the inner hole of the hard and brittle pipe 5.
[0051] S22, Finishing stage: The guide section 1 of the finishing grinding tool penetrates the inner hole of the hard and brittle pipe 5, straightens the finishing grinding tool and supports it with a support device, and the finishing grinding tool rotates uniformly at a speed of 100 rpm / min. At the same time, free-falling polishing liquid is provided on both sides of the finishing grinding tool. The polishing liquid is sucked into the annular groove 4 of the finishing grinding tool. The hard and brittle pipe 5 moves forward to ensure that there is polishing liquid between the annular groove 4 and the inner wall of the hard and brittle pipe 5. The hard and brittle pipe 5 moves back and forth in a large span from the guide section 1 to the sizing section 3 along the length direction of the finishing grinding tool until the hard and brittle pipe 5 moves to the sizing section 3 and is ground to achieve the finishing of the inner hole of the hard and brittle pipe 5.
[0052] Example 3:
[0053] This embodiment provides a method for grinding the inner hole of hard and brittle pipes with a large length-to-diameter ratio. It utilizes a roughing grinding tool with a liquid injection channel and a finishing grinding tool with a liquid injection channel. The grinding steps are as follows:
[0054] S1, determine the number of machining operations for the hard and brittle pipe fitting, the number of grinding tools, and the outer diameter of each grinding tool:
[0055] Let the target size of the inner bore of the brittle pipe be D. n The actual minimum diameter of the inner bore of a hard and brittle pipe fitting is D. nmin The single grinding depth Δd and the taper difference Δa (the diameter difference from the starting position to the ending position of the taper segment) of the hard and brittle pipe fitting are given. The number of grinding tools is m. To eliminate the initial dimensional error of the inner hole of the hard and brittle pipe fitting, the inner hole of the hard and brittle pipe fitting is usually pre-treated using the first grinding tool. The diameter of the sizing section of the first grinding tool is the minimum inner diameter D of the hard and brittle pipe fitting. nmin When the minimum inner diameter D of the hard and brittle pipe fitting is used nmin When hard and brittle pipe fittings cannot pass effectively during the sizing section of the grinding tool, the number of pre-treatment grinding cycles should be increased. Therefore, the number of processing cycles n for hard and brittle pipe fittings is expressed as:
[0056] The diameter of the sizing grinding head of the i-th grinding tool satisfies the following relationship: D i+1 =Δd+D i ,i∈(0,n)
[0057] The diameter of the guide grinding head of the i-th grinding tool satisfies the following relationship: D min =D i+1 -Δa,i∈(0,n)
[0058] S2, according to the number of times the hard and brittle pipe is processed, the inner hole of the hard and brittle pipe is processed in sequence according to the grinding tools from the 1st to the mth pipe;
[0059] S21, Rough machining stage: The guide section 1 of the rough machining grinding tool penetrates the inner hole of the hard and brittle pipe 5 and straightens the rough machining grinding tool. The rough machining grinding tool rotates uniformly at a speed of 100 rpm / min. At the same time, coolant is injected into the injection channel by pumping coolant. The coolant is thrown to the annular groove 4 to keep the annular groove 4 and the inner wall of the hard and brittle pipe 5 containing coolant. The hard and brittle pipe 5 moves back and forth from the guide section 1 to the sizing section 3 along the length direction of the rough machining grinding tool until the hard and brittle pipe 5 moves to the sizing section 3 and is ground to achieve rough machining of the inner hole of the hard and brittle pipe 5.
[0060] S22, Finishing stage: The guide section 1 of the finishing grinding tool penetrates the inner hole of the hard and brittle pipe 5 and straightens the finishing grinding tool. The finishing grinding tool rotates uniformly at a speed of 100 rpm / min. At the same time, the grinding fluid is injected into the injection channel by pumping the grinding fluid. The grinding fluid is thrown to the annular groove 4 to ensure that there is polishing fluid between the annular groove 4 and the inner wall of the hard and brittle pipe 5. The hard and brittle pipe 5 moves back and forth along the length direction of the finishing grinding tool towards the sizing section 3 until the hard and brittle pipe 5 moves to the sizing section 3 and is ground to achieve the finishing of the inner hole of the hard and brittle pipe 5.
[0061] Examples 2 and 3 are identical except for the method of fluid flow. Using multiple grinding tools of proportionally increasing size in multiple passes for the same hard and brittle pipe not only ensures the grinding accuracy of the workpiece but also reduces the probability of low-level damage to the hard and brittle pipe. The number of roughing grinding tools used in the roughing stage and the number of finishing grinding tools used in the finishing stage depend on the actual situation.
[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions created by the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions created by the present invention without departing from the essence and scope of the technical solutions created by the present invention.
Claims
1. A lapping tool for lapping the bore of a hard and brittle tubular member of large length-to-diameter ratio, characterized in that, It is a large length-to-diameter ratio grinding tool consisting of annular grinding heads and annular grooves arranged alternately. Along the length of the grinding tool, it is divided into three sections: a guide section, a tapered section, and a sizing section. The guide section is used to penetrate the inner hole of hard and brittle pipes. The tapered section is used for grinding and enlarging the inner hole of hard and brittle pipes. The sizing section is used for sizing grinding the inner hole of hard and brittle pipes. The grinding tool passes through the inner hole of the hard and brittle pipe through the guide section and is straightened. The grinding tool rotates, and the hard and brittle pipe moves from the guide section to the sizing section while also reciprocating until the hard and brittle pipe moves to the sizing section and is ground, so as to realize the processing of the inner hole of the hard and brittle pipe.
2. The abrasive tool for inside grinding of a hard and brittle pipe having a large length-diameter ratio according to claim 1, wherein The length ratio of the guide section, tapered section and sizing section is 1:3:1 to 1:4:1; the length ratio of the rigid and brittle pipe fitting to the guide section is 5:
6.
3. The abrasive tool for inside grinding of a hard and brittle pipe with a large length-diameter ratio according to claim 1, characterized in that, The annular grinding head of the guide section is a guide grinding head of equal diameter.
4. The abrasive tool for abrasive lapping of the bore of a hard and brittle pipe having a large length-to-diameter ratio according to claim 3, characterized in that The tapered annular grinding head is a tapered enlarged diameter grinding head, with the outer diameter of the enlarged diameter grinding head gradually increasing along the forward direction of the hard and brittle pipe.
5. A tool for honing the bore of a hard and brittle tubular element of large length-diameter ratio according to claim 4, characterized in that, The annular grinding head in the sizing section is a sizing grinding head with a constant diameter.
6. The abrasive tool for inside grinding of a hard and brittle pipe with a large length-diameter ratio according to claim 1, characterized in that, The grinding tool has a liquid injection channel along its length, and a drain hole that runs through the liquid injection channel is opened at the annular groove. Grinding liquid or coolant is injected into the liquid injection channel, and the grinding liquid or coolant is thrown to the annular groove to cool or grind the inner hole of the hard and brittle pipe.
7. The abrasive tool for inside grinding of a hard and brittle pipe with a large length-diameter ratio according to claim 5, characterized in that, Diamond micropowder is electroplated onto the surface of the ring grinding head to make it a roughing grinding tool; or the surface of the ring grinding head is textured to make it a finishing grinding tool.
8. A method of honing an internal bore of a hard and brittle tubular member of large length-to-diameter ratio, characterized in that, This is achieved using the grinding tool as described in claim 7, and the specific process is as follows: S1, determine the number of machining operations for the hard and brittle pipe fitting, the number of grinding tools, and the outer diameter of each grinding tool: D is a target dimension of the inner hole of the hard brittle pipe n D is an actual minimum inner diameter of the inner hole of the hard brittle pipe nmin Δd is a single grinding amount of the hard brittle pipe, and Δa is a taper difference of the taper section of the grinding tool, the number of the grinding tools is m; the number of processing n of the hard brittle pipe is expressed as: Diameter D of the sizing cup of the i-th abrasive tool i+1 satisfies the following relation: D i+1 = Δd + D i i ∈ (0, n) The diameter D' of the guide grinding head of the i-th grinding tool satisfies the following relationship: D' = D i+1 - Δa, i ∈ (0, n) S2, according to the number of times the hard and brittle pipe is processed, the inner hole of the hard and brittle pipe is processed in sequence according to the grinding tools from the first to the mth pipe; S21 Roughing stage: The roughing grinding tool penetrates the inner hole of the hard and brittle pipe and straightens it. While the roughing grinding tool rotates, coolant is kept between the annular groove and the inner wall of the hard and brittle pipe. The hard and brittle pipe moves from the guide section to the sizing section and also moves back and forth until the hard and brittle pipe moves to the sizing section and is ground, so as to achieve roughing of the inner hole of the hard and brittle pipe. S22, Finishing stage: The finishing grinding tool penetrates the inner hole of the hard and brittle pipe and straightens it. While the finishing grinding tool rotates, it keeps the grinding fluid between the annular groove and the inner wall of the hard and brittle pipe. The hard and brittle pipe moves from the guide section to the sizing section and also moves back and forth until the hard and brittle pipe moves to the sizing section and is ground, so as to achieve the finishing of the inner hole of the hard and brittle pipe.
9. A method of honing an internal bore of a hard and brittle tubular member of large length-to-diameter ratio according to claim 8, characterized in that, In step S1, free-falling coolant is provided on both sides of the roughing grinding tool. The coolant is drawn into the annular groove of the roughing grinding tool, and the hard and brittle tube moves forward to ensure that there is coolant between the annular groove and the inner wall of the hard and brittle tube. In step S2, free-falling polishing fluid is provided on both sides of the finishing grinding tool. The polishing fluid is drawn into the annular groove of the finishing grinding tool, and the hard and brittle tube moves forward to ensure that there is polishing fluid between the annular groove and the inner wall of the hard and brittle tube.
10. A method of honing an internal bore of a hard and brittle tubular member of large length-to-diameter ratio according to claim 8, characterized in that, The roughing grinding tool has a liquid injection channel along its length, and a drain hole through the liquid injection channel is opened at the annular groove. Coolant is injected into the liquid injection channel and is thrown to the annular groove to ensure that there is coolant between the annular groove and the inner wall of the hard and brittle tube. The finishing grinding tool has a liquid injection channel along its length, and a drain hole through the liquid injection channel is opened at the annular groove. Grinding fluid is injected into the liquid injection channel and is thrown to the annular groove to ensure that there is polishing fluid between the annular groove and the inner wall of the hard and brittle tube.