A rubber bladder inflatable reciprocating feed internal flow channel grinding tool and method of use

Abstract

The application discloses a rubber bag inflation reciprocating feeding type internal flow channel grinding tool and a use method. The tool comprises a tool handle, a plurality of rubber bags and intermediate abrasive grains are connected at the bottom of the tool handle in intervals, and the last intermediate abrasive grain is connected with a head abrasive grain through a rubber bag. A retraction spring is arranged between the tool handle and the first rubber bag, between the rubber bags and the intermediate abrasive grains, between the intermediate abrasive grains and the last rubber bag, and between the last rubber bag and the head abrasive grain, so as to form a tool grinding working part. The air channel of the tool handle is connected with an external air source through a pipeline penetrating through the center of a main shaft of a machine tool, and the tool handle is clamped on a chuck of the main shaft of the machine tool. The external air source with a gas charging and discharging frequency is introduced, so that the tool generates high-frequency reciprocating cutting motion, and the grinding of the internal flow channel is completed in a short time. The application can realize the finishing machining of the additive manufacturing complex internal flow channel, and is beneficial to the improvement of the surface quality of the additive manufacturing part.

Description

Technical Field

[0001] This invention belongs to the field of additive and subtractive composite manufacturing technology, specifically relating to a rubber bladder inflatable reciprocating feed internal flow channel grinding tool and its usage method. Background Technology

[0002] Additive manufacturing technology is widely used in the manufacture of complex structural parts in aerospace due to its significant advantages in rapidly manufacturing complex-shaped parts and shortening the manufacturing cycle of parts.

[0003] Hot-end components of aero-engines must withstand the impact of high-temperature, high-pressure combustion gases. Cooling channels are typically added internally to improve their cooling performance. These components are made of nickel-based superalloys, with small internal flow channel cross-sections (diameter between φ4-φ10mm), requiring high surface roughness (generally less than Ra 0.8μm) and exhibiting a narrow, S-shaped distribution, making them difficult to manufacture using traditional methods. Selective laser melting (SLM) technology, with its advantages of high forming accuracy, strong ability to form complex structures, and high processing speed, has been widely used in the manufacturing of aerospace parts with complex internal flow channels. However, phenomena such as powder spheroidization, powder adhesion, and step effects result in poor surface quality of SLM-processed parts, with surface roughness generally between 10-50μm. This causes poor flow of coolant within the internal channels, low cooling efficiency, and affects the actual performance of parts with complex internal flow channels. Therefore, finishing processing is required for the internal flow channels of additively manufactured aero-engine hot-end components.

[0004] Currently, abrasive flow technology is commonly used to polish internal flow channels. This method requires removing the part from the substrate using wire EDM after the additive manufacturing process is completed, and then mounting it on an abrasive flow polishing machine for finishing. This method increases production costs and extends processing time, and it cannot handle closed internal flow channel structures.

[0005] Therefore, using additive and subtractive manufacturing to treat internal flow channels, with its simultaneous forming and machining characteristics, can effectively improve the surface quality of internal flow channels. However, traditional milling tools (Mu JR, Sun TT, Leung CL, et al. Application of electrochemical polishing in surface treatment of additively manufactured structures: A review[J]. Progress in Materials Science, 2023, 136: 101109) are mostly cylindrical in structure. When machining complex internal flow channels (such as some negative angle and S-shaped flow channel structures), due to the limitations of free-form surfaces and narrow milling operation space, the feed rate of the tool varies in different machining areas, and there may even be interference between the tool and the workpiece. Therefore, it is difficult to obtain a uniform surface roughness, resulting in poor surface quality of internal flow channels and affecting actual service performance. Therefore, it is urgent to develop cutting tools suitable for finishing complex internal flow channels. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention aims to provide a rubber bladder inflatable reciprocating feed internal flow channel grinding tool and its usage method, which can realize the finishing of complex internal flow channels in additive manufacturing and is beneficial to improving the surface quality of additive manufacturing parts.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A rubber bladder-inflated reciprocating feed internal flow channel grinding tool includes a tool holder 1. Several rubber bladders 4 and intermediate abrasive grains 7 are connected at intervals at the bottom of the tool holder 1. The last intermediate abrasive grain 7 is connected to a rubber bladder 4 and an end abrasive grain 8. A return spring 6 is provided between the tool holder 1 and the first rubber bladder 4, between the rubber bladder 4 and the intermediate abrasive grains 7, between the intermediate abrasive grains 7 and the last rubber bladder 4, and between the last rubber bladder 4 and the end abrasive grain 8 to form the tool grinding working part.

[0009] The knife handle 1 includes a knife handle air passage 2 and a knife handle fixing groove 3. The knife handle air passage 2 is located in the center of the knife handle 1, and the inlet of the knife handle air passage 2 is connected to an external air source. The knife handle fixing groove 3 is located at the bottom of the knife handle 1, and a rubber bladder 4 and a retraction spring 6 are fixed on the knife handle fixing groove 3.

[0010] The intermediate abrasive 7 includes a first abrasive layer 71, which wraps around a first substrate 73. An abrasive air passage 74 is provided in the center of the first substrate 73. The abrasive air passage 74, together with the tool holder air passage 2 and the rubber bladder 4, forms an airflow channel. Intermediate abrasive fixing slots 72 are provided at both ends of the first substrate 73. A retraction spring 6 and a rubber bladder 4 are installed in the intermediate abrasive fixing slots 72.

[0011] The first abrasive layer 71 is made of diamond abrasive grains and adhesive, and the first abrasive layer 71 is fixed on the first substrate 73 by adhesive; the first abrasive layer 71 is spherical in shape, and the first cutting edge 75 is evenly arranged on the outer side of the first abrasive layer 71.

[0012] The end abrasive 8 includes a second abrasive layer 81, which wraps around a second substrate 83. The upper part of the second substrate 83 is provided with an end abrasive fixing groove 82, and a retraction spring 6 and a rubber bladder 4 are installed in the end abrasive fixing groove 82.

[0013] The second abrasive layer 81 is spherical in shape, and the second cutting edge 84 is evenly arranged on the outer side of the second abrasive layer 81; the head of the second abrasive layer 81 is designed to be hemispherical, which can guide the tool to move in the complex internal flow channel.

[0014] The retraction spring 6 is in a naturally straight state when installed. After the rubber bladder 4 is inflated, the retraction spring 6 stretches along with the rubber bladder 4. After the rubber bladder 4 is deflated, the retraction spring 6 provides the rubber bladder 4 with a rapid and complete return capability.

[0015] The rubber bladder 4 is installed in the handle fixing slot 3, the intermediate abrasive fixing slot 72 or the end abrasive fixing slot 82, and is in a naturally straight state during installation.

[0016] The upper and lower folding parts of the rubber bladder 4 are fitted with explosion-proof steel rings 5, which are put on the rubber bladder 4 before it is inflated.

[0017] The method of using a rubber bladder-inflated reciprocating feed internal flow channel grinding tool includes: connecting the tool holder air passage 2 to an external air source through a pipe passing through the center of the machine tool spindle, and clamping the tool holder 1 in the chuck of the machine tool spindle; introducing an external air source with an inflation and deflation frequency to make the tool generate a high-frequency reciprocating cutting motion, thereby completing the grinding of the internal flow channel in a short time.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) The present invention uses a rubber bladder 4 and a retraction spring 6 to form an abrasive grain connection mechanism, which can be bent to a certain extent to adapt to internal flow channels of different shapes and realize the finishing process of complex internal flow channels in SLM additive manufacturing.

[0020] (2) The present invention can use a spherical first abrasive layer 71 and a second abrasive layer 81 with a diameter of 4mm. The outer side of the first abrasive layer 71 and the second abrasive layer 81 is provided with 25 evenly distributed first cutting edges 75 and second cutting edges 84, which ensures that the middle abrasive grains 7 and the end abrasive grains 8 can adapt to the complex internal flow channel with a cross-sectional diameter of 4mm, ensuring that there is sufficient contact area between the abrasive grains and the hole wall, and providing sufficient grinding force for the tool.

[0021] (3) The tool holder 1 of the present invention is directly clamped on the machine tool spindle during operation, which has the advantages of easy installation and good replaceability.

[0022] (4) The present invention uses a rubber bladder 4 and a retraction spring 6 to realize the reciprocating feeding motion of the intermediate abrasive grains 7 and the end abrasive grains 8. The mechanical structure is simple and reliable. Under the push of high pressure gas, the grinding force is sufficient to ensure the surface quality of the internal flow channel. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0024] Figure 2 This is a cross-sectional view of the internal structure of the present invention.

[0025] Figure 3 This is a partial enlarged view of the connection part I between the knife handle and the rubber bladder of the present invention.

[0026] Figure 4 This is a partial enlarged view of the connection portion II between the abrasive grains and the rubber capsule in this invention.

[0027] Figure 5 This is a cross-sectional view of the internal structure of the present invention after being filled with high-pressure gas. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0029] like Figures 1-4 As shown, a rubber bladder-inflated reciprocating feed internal flow channel grinding tool includes a tool holder 1. Rubber bladders 4 and intermediate abrasive grains 7 are connected at intervals at the bottom of the tool holder 1. In this embodiment, four rubber bladders 4 and three intermediate abrasive grains 7 are provided. The last intermediate abrasive grain 7 is connected to a rubber bladder 4 and an end abrasive grain 8. Retraction springs 6 are provided between the tool holder 1 and the first rubber bladder 4, between the rubber bladder 4 and the intermediate abrasive grains 7, between the intermediate abrasive grains 7 and the last rubber bladder 4, and between the last rubber bladder 4 and the end abrasive grain 8, forming a complete tool grinding working part.

[0030] The knife handle 1 includes a knife handle air passage 2 and a knife handle fixing groove 3. The knife handle air passage 2 is located in the center of the knife handle 1. The inlet of the knife handle air passage 2 is connected to an external air source to realize the rapid filling and extraction of gas. The bottom of the knife handle 1 is provided with a knife handle fixing groove 3. A rubber bladder 4 and a retraction spring 6 are fixed to the knife handle fixing groove 3 by adhesive bonding.

[0031] The intermediate abrasive 7 includes a first abrasive layer 71, which wraps around a first substrate 73. An abrasive air passage 74 is located at the center of the first substrate 73. This abrasive air passage 74, together with the tool holder air passage 2 and the rubber bladder 4, forms an airflow channel, ensuring smooth airflow within the tool. Intermediate abrasive fixing slots 72 are located at both ends of the first substrate 73, and a retraction spring 6 and a rubber bladder 4 are installed within each slot. The first abrasive layer 71 is composed of diamond abrasive grains and an adhesive, and is fixed to the first substrate 73 by the adhesive. The first abrasive layer 71 has a spherical shape with a diameter of 4mm, allowing it to process internal flow channels with a cross-sectional diameter of 4mm and flexibly adapt to various curvatures of internal surfaces. Twenty-five first cutting edges 75 are evenly arranged on the outer side of the first abrasive layer 71, providing sufficient and reliable grinding force to the tool.

[0032] The end abrasive grain 8 includes a second abrasive layer 81, which wraps around a second substrate 83. The upper part of the second substrate 83 is provided with an end abrasive grain fixing groove 82, in which a retraction spring 6 and a rubber bladder 4 are installed. The second abrasive layer 81 is spherical in shape with a diameter of 4 mm, which can be used to process internal flow channels with a cross-sectional diameter of 4 mm and can flexibly adapt to internal surfaces with various curvatures. 25 second cutting edges 84 are evenly arranged on the outer side of the second abrasive layer 81, which can provide sufficient and reliable grinding force for the tool. The head of the second abrasive layer 81 is designed as a hemispherical shape, which can guide the tool to move in complex internal flow channels.

[0033] The two ends of the retraction spring 6 are installed in the tool holder fixing groove 3 and the intermediate abrasive fixing groove 72. The two ends of the retraction spring 6 are fixed to the two ends of the rubber bladder 4 by adhesive bonding. When installed, the retraction spring 6 is in a naturally straight state. After the rubber bladder 4 is inflated, the retraction spring 6 stretches along with the rubber bladder 4. After the rubber bladder 4 is deflated, the retraction spring 6 can provide the rubber bladder 4 with a fast and complete return capability, which improves the overall operating efficiency of the mechanism.

[0034] The rubber bladder 4 is installed at both ends in the handle fixing slot 3 and the middle abrasive fixing slot 72, and is fixedly connected to the two ends of the tension spring 6 by adhesive bonding to ensure concentricity. It is in a naturally straight state during installation. In addition, explosion-proof steel rings 5 ​​are fitted on the upper and lower folding parts of the rubber bladder 4. The explosion-proof steel rings 5 ​​are put on before the rubber bladder 4 is inflated, which increases the safety of the rubber bladder 4 and the pressure bearing capacity of the force-bearing surface of the rubber bladder 4.

[0035] like Figure 5 As shown, the working principle of this invention is as follows: the rubber bladder inflatable reciprocating feed internal flow channel grinding tool extends to the expected length after inflation. Each rubber bladder 4 expands and extends under the action of high-pressure gas, pushing the intermediate abrasive grains 7 and the end abrasive grains 8 forward. Under the action of high-pressure gas, the intermediate abrasive grains 7 and the end abrasive grains 8 both extend by 2mm (half the diameter of the intermediate abrasive grains 7 and the end abrasive grains 8). The return spring 6 follows the stretching of the rubber bladder 4, storing sufficient elastic potential energy. After the high-pressure gas is extracted, it can provide sufficient and rapid return force for the intermediate abrasive grains 7, the end abrasive grains 8 and the rubber bladder 4, improving the overall operating efficiency of the mechanism. The frequency of inflation and deflation of the external air source can reach 60 times per minute, which can realize the rapid feed and return of the tool in a short time and complete the finishing of the internal flow channel. With the synchronous cooperation of the high-frequency external air source and up to 25 first cutting edges 75 and second cutting edges 84 of each intermediate abrasive grain 7 and the end abrasive grain 8, the finishing of the surface of the internal flow channel can be achieved quickly, so that the surface roughness of the inner surface is <Ra 0.8μm.

[0036] The method of using a rubber bladder inflatable reciprocating feed internal flow channel grinding tool includes:

[0037] Before grinding, the tool holder air passage 2 is connected to an external air source through a pipe passing through the center of the machine tool spindle, and the tool holder 1 is clamped in the machine tool chuck. First, high-pressure gas is introduced to extend the rubber bladder 4 and the return spring 6, ensuring that the tool has a certain rigidity. Then, the machine tool spindle feeds axially along the center line of the internal flow channel, slowly feeding the tool into the internal flow channel. With the cooperation of the spherical intermediate abrasive grains 7 and the end abrasive grains 8, the tool is positioned in the internal flow channel. Then, the high-pressure gas inside the tool is quickly extracted, the rubber bladder 4 contracts, and the intermediate abrasive grains 7 and the end abrasive grains 8 return to their original positions under the elastic force of the return spring 6, completing the tool positioning preparation work before grinding.

[0038] After the tool is positioned, grinding begins. An external air source with a charging and decharging frequency of 60 times per minute is introduced, causing the tool to generate a high-frequency reciprocating cutting motion, completing the grinding of the internal flow channels in a short time. The grinding process consists of multiple single grinding steps, and the working principle of a single grinding step is as follows:

[0039] First, an external air source fills the cutting tool with high-pressure gas, causing the rubber bladder 4 to expand rapidly. This expands the return spring 6, pushing the intermediate abrasive grains 7 and the terminal abrasive grains 8 along the internal flow channel axis. Each rubber bladder 4 extends by 2 mm, and the intermediate abrasive grains 7 and the terminal abrasive grains 8, with a diameter of 4 mm, grind the inner wall of the flow channel with a cross-sectional diameter of 4 mm under the push of the rubber bladder 4. The grinding amount per pass is 2 mm. The 25 first cutting edges 75 and second cutting edges 84 evenly arranged on the first abrasive layer 71 and the second abrasive layer 81 provide uniform grinding force to the inner wall of the flow channel. The explosion-proof steel rings 5 ​​at the upper and lower folding parts of the rubber bladder 4 increase the safety of the rubber bladder 4 and the pressure-bearing capacity of the force-bearing surface of the rubber bladder 4. The return spring 6 extends during inflation, storing sufficient elastic potential energy, which can provide sufficient and rapid return force to the intermediate abrasive grains 7, the terminal abrasive grains 8, and the rubber bladder 4 after the high-pressure gas is extracted, improving the overall operating efficiency of the mechanism.

[0040] Subsequently, the external air source rapidly extracts the high-pressure gas from inside the tool, causing the rubber bladder 4 to contract quickly. Driven by the elastic force stored in the return spring 6, the intermediate abrasive grains 7 and the terminal abrasive grains 8 rapidly retract. The 25 first cutting edges 75 and second cutting edges 84, evenly arranged on the first abrasive layer 71 and the second abrasive layer 81, complete the secondary grinding of the inner wall of the flow channel, further improving the surface quality of the internal flow channel. Under the action of the elastic force of the return spring 6, all rubber bladders 4, intermediate abrasive grains 7, and terminal abrasive grains 8 return to the state of the tool's natural extension. Within one inflation and deflation cycle of the external air source, the tool completes one grinding step of the internal flow channel.

[0041] After one grinding step is completed, the external air source rapidly injects high-pressure gas again, causing the rubber bladder 4 to expand and proceed to the next grinding step. Under the action of the rapid circulation of gas from the external air source, the intermediate abrasive grains 7 and the terminal abrasive grains 8 of the tool reciprocate within the inner hole. The 25 first cutting edges 75 and second cutting edges 84 evenly arranged on the first abrasive layer 71 and the second abrasive layer 81 achieve high-frequency grinding of the hole wall, reaching 60 times per minute, ensuring a high surface quality of the inner wall of the flow channel. The grinding time for a single grinding process is between 20 and 30 seconds, which can achieve a surface quality of <Ra0.8μm for the internal flow channel in additive manufacturing.

[0042] Because the tool performs high-frequency grinding with a small feed rate in each grinding step, the grinding depth of each intermediate abrasive grain 7 and the terminal abrasive grain 8 in a single grinding process is only 2mm, resulting in some inner walls of the internal flow channel not being finished. Therefore, after completing one full grinding process, the machine tool spindle is moved 2mm along the z-axis, and then the unprocessed area is ground. The above process is repeated until all unprocessed areas are ground, achieving the finishing of the internal flow channel and making the surface quality of the internal flow channel < Ra 0.8μm.

[0043] After the grinding work is completed, the machine tool spindle slowly moves upward to complete the tool retraction process and remove the chips from the grinding process, thereby achieving high-quality finishing of the nickel-based superalloy internal flow channel parts manufactured by SLM additive manufacturing and improving the surface quality of the additive manufacturing internal flow channels.

[0044] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rubber bladder-inflated reciprocating feed internal flow channel grinding tool, comprising a tool holder (1), characterized in that: The bottom of the tool holder (1) is connected with several rubber bladders (4) and intermediate abrasive grains (7) at intervals. The last intermediate abrasive grain (7) is connected to a rubber bladder (4) and an end abrasive grain (8). A retraction spring (6) is provided between the tool holder (1) and the first rubber bladder (4), between the rubber bladder (4) and the intermediate abrasive grain (7), between the intermediate abrasive grain (7) and the last rubber bladder (4), and between the last rubber bladder (4) and the end abrasive grain (8) to form the tool grinding working part. The knife handle (1) includes a knife handle air passage (2) and a knife handle fixing slot (3). The knife handle air passage (2) is located in the center of the knife handle (1), and the inlet of the knife handle air passage (2) is connected to an external air source. The knife handle (1) has a knife handle fixing slot (3) at the bottom, and a rubber bag (4) and a retraction spring (6) are fixed on the knife handle fixing slot (3). The intermediate abrasive (7) includes a first abrasive layer (71), which is wrapped around a first substrate (73). An abrasive air passage (74) is provided in the center of the first substrate (73). The abrasive air passage (74), together with the tool holder air passage (2) and the rubber bladder (4), forms an airflow channel. Intermediate abrasive fixing slots (72) are provided at both ends of the first substrate (73). A retraction spring (6) and a rubber bladder (4) are installed in the intermediate abrasive fixing slots (72). The retraction spring (6) is in a naturally straight state when installed. After the rubber bladder (4) is inflated, the retraction spring (6) stretches along with the rubber bladder (4). After the rubber bladder (4) is deflated, the retraction spring (6) provides the rubber bladder (4) with a fast and complete return capability.

2. The cutting tool according to claim 1, characterized in that: The first abrasive layer (71) is made of diamond abrasive grains and adhesive. The first abrasive layer (71) is fixed on the first substrate (73) by adhesive. The first abrasive layer (71) has a spherical shape and the first cutting edge (75) is evenly arranged on the outer side of the first abrasive layer (71).

3. The cutting tool according to claim 1, characterized in that: The end abrasive (8) includes a second abrasive layer (81), which is wrapped around a second substrate (83). The upper part of the second substrate (83) is provided with an end abrasive fixing groove (82), and a retraction spring (6) and a rubber bladder (4) are installed in the end abrasive fixing groove (82).

4. The cutting tool according to claim 3, characterized in that: The second abrasive layer (81) is spherical in shape, and the second cutting edge (84) is evenly arranged on the outer side of the second abrasive layer (81); the head of the second abrasive layer (81) is designed as a hemispherical shape, which can guide the tool to move in the complex internal flow channel.

5. The cutting tool according to claim 3, characterized in that: The rubber bladder (4) is installed in the handle fixing slot (3), the middle abrasive fixing slot (72) or the end abrasive fixing slot (82), and is in a naturally straight state during installation.

6. The cutting tool according to claim 1, characterized in that: The upper and lower folding parts of the rubber bladder (4) are fitted with explosion-proof steel rings (5), which are put on the rubber bladder (4) before it is inflated.

7. A method of using a rubber bladder-inflated reciprocating feed internal flow channel grinding tool according to any one of claims 1-6, characterized in that, include: Connect the tool holder air passage (2) to an external air source through a pipe passing through the center of the machine tool spindle, and clamp the tool holder (1) onto the chuck of the machine tool spindle; An external air source with a charging and discharging frequency is introduced to cause the tool to generate a high-frequency reciprocating cutting motion, which completes the grinding of the internal flow channel in a short time.

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