Gear test fixture apparatus and method of reducing gear test diametral modal frequency

Abstract

The present invention proposes a gear test fixture device and a method for reducing the pitch modal frequency of a gear test. The fixture device includes a tabletop transition section, a pressing member, and a test piece gear, wherein the pressing member presses and fixes the test piece gear on the tabletop transition section, and the tabletop transition section is fixed on a vibration table; a counterweight is fixed on the test piece gear in a detachable manner. The counterweight includes an upper counterweight and a lower counterweight, wherein the upper counterweight and the lower counterweight are respectively fixed on the upper and lower sides of the test piece gear by clamping. The counterweight is used to reduce the pitch modal frequency of the spur gear. On the one hand, the operating frequency of the vibration table can meet the test frequency requirements; on the other hand, the vibration displacement response of the spur gear can be improved during the test.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aero-engine, and particularly relates to a gear test fixture device and a method for reducing the gear test pitch circle modal frequency. BACKGROUND

[0002] The existing high-cycle fatigue test fixture of the spur gear of the aero-engine accessory drive is directly pressed against the shaft neck of the spur gear by a pressing block and is installed on a vibration table to perform high-cycle fatigue test. During the test, the spur gear produces large displacement amplitude vibration under the excitation of the pitch circle modal frequency, and large stress is generated at the most dangerous cross section of the spur gear to cause fatigue failure.

[0003] The existing technology is to press the upper and lower end faces of the shaft neck of the spur gear and install the spur gear on a vibration table to perform high-cycle fatigue test. However, due to the small size of the spur gear of the aero-engine accessory drive and the high pitch circle modal frequency, on the one hand, the working frequency range of most existing vibration tables cannot meet the requirements, resulting in that the test cannot be performed; on the other hand, even if the working frequency range of a certain type of vibration table can meet the test requirements, it is still very difficult to make the spur gear produce large amplitude vibration displacement at a high frequency, and the vibration displacement response of the spur gear under the maximum thrust of the vibration table cannot cause the spur gear to produce fatigue failure, resulting in that the high-cycle fatigue test results of the spur gear cannot be obtained.

[0004] The spur gear is a key part of the aero-engine accessory drive and often bears alternating loads. The vibration fatigue test of the spur gear is used to determine the fatigue life of the spur gear under different alternating loads or the fatigue limit of the spur gear under a specified life, and can also be used for fault analysis and design improvement verification. The size of the spur gear of the aero-engine accessory drive is small, and the pitch circle modal frequency is high. When the high stress level high-cycle fatigue test of the spur gear is performed on the vibration table, the working frequency range of the vibration table often cannot meet the requirements of the test frequency of the spur gear. Even if the working frequency range of the vibration table can meet the requirements of the test frequency of the spur gear, under a relatively high test frequency, the vibration table cannot obtain the vibration displacement response of the spur gear to produce fatigue failure under the maximum thrust. SUMMARY

[0005] In view of the above problems, the present application provides a high-cycle fatigue test fixture device for the spur gear of an aero-engine, which is configured to set a counterweight structure of a test piece spur gear to counterweight the test piece spur gear and reduce the pitch circle modal frequency of the spur gear.

[0006] The present application provides a gear test fixture device, which comprises a table surface adapter, a pressing member and a test piece gear, wherein the pressing member is configured to press and fix the test piece gear on the table surface adapter, and the table surface adapter is fixed on a vibration table; and the test piece gear is characterized in that a counterweight block is fixed on the test piece gear in a detachable manner.

[0007] Further, the counterweight block includes an upper counterweight block and a lower counterweight block, wherein the upper counterweight block and the lower counterweight block are fixed on the upper side and the lower side of the test gear respectively by clamping.

[0008] Further, the upper counterweight block is uniformly distributed with a plurality of upper counterweight block through holes along the circumference; the lower counterweight block is uniformly distributed with a plurality of lower counterweight block through holes along the circumference; the number of the upper counterweight block through holes is the same as that of the lower counterweight block through holes, and they are one-to-one corresponding.

[0009] Further, a plurality of counterweight bolts pass through the upper counterweight block through holes and the lower counterweight block through holes, and are compressed by a plurality of counterweight nuts, so that the upper counterweight block and the lower counterweight block clamp the test gear.

[0010] Further, the table adapter section is composed of a base and a mounting shaft, the base is provided with a plurality of bolt holes, a plurality of bolts pass through the plurality of bolt holes to fix the table adapter section on the vibration table, and the compression member compresses and fixes the test gear on the mounting shaft of the table adapter section.

[0011] Further, the upper counterweight block has a disc structure, including a thick wall part on the outer side and a thin wall part on the inner side; the upper counterweight block through holes are uniformly distributed on the thin wall part along the circumference; the upper counterweight block is specifically a central symmetric structure, the center of gravity of the upper counterweight block coincides with the shaft center.

[0012] Further, the lower counterweight block has a disc structure, including a thick wall part on the outer side and a thin wall part on the inner side. The lower counterweight block through holes are uniformly distributed on the thin wall part along the circumference; the lower counterweight block is specifically a central symmetric structure, the center of gravity of the lower counterweight block coincides with the shaft center.

[0013] Further, the mounting shaft of the table adapter section is a stepped cylindrical structure, specifically including a large diameter section in the lower part and a small diameter section in the upper part, the connection part of the large diameter section and the small diameter section forms a shoulder structure which can abut against the test gear; the small diameter section includes a smooth rod section in the lower part and a threaded section in the upper part; the mounting shaft of the table adapter section is specifically a central symmetric structure, the center of gravity of the mounting shaft coincides with the shaft center.

[0014] Further, the plurality of bolt holes are arranged in two groups, the first group of the bolt holes are uniformly distributed on the first circumference of the base along the circumference; the second group of the bolt holes are uniformly distributed on the second circumference of the base along the circumference, the diameter of the first circumference is larger than that of the second circumference.

[0015] The application further provides a method for reducing the pitch circle modal frequency of a gear, which uses the gear test fixture device according to any one of the preceding aspects, and is characterized in that the pitch circle modal frequency of the gear is reduced by counterweighting the gear.

[0016] Compared with the prior art, the application has the following advantages:

[0017] The gear test fixture device of the application reduces the pitch circle modal frequency of a spur gear by using a counterweight. On the one hand, the pitch circle modal frequency of the spur gear is reduced to the operating frequency range of the vibration table, so that the operating frequency of the vibration table can meet the test frequency requirement. On the other hand, the vibration displacement response of the spur gear can be improved during the test, so that the spur gear can obtain a larger vibration displacement response and cause fatigue failure under a relatively small output of the vibration table, and the high-cycle fatigue test result of the spur gear can be obtained under a relatively small thrust of the vibration table. Further, the requirement for the frequency and thrust of the vibration table is reduced, the vibration table does not need to be replaced, and the test cost is reduced.

[0018] Other features and advantages of the application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the application or in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0020] Figure 1 A schematic diagram of the main structure of the fixture device in the embodiment of the application is shown;

[0021] Figure 2 A schematic diagram of the table surface adapter section in the embodiment of the application is shown;

[0022] Figure 3 A schematic diagram of the upper counterweight in the embodiment of the application is shown;

[0023] Figure 4 A schematic diagram of the lower counterweight in the embodiment of the application is shown;

[0024] Figure 5 A schematic diagram of the partially assembled fixture device in the embodiment of the application is shown.

[0025] In the figure, 1, mesa adapter section; 2, compression nut; 3, test piece spur gear; 4, counterweight bolt; 5, counterweight nut; 6, upper counterweight block; 7, lower counterweight block; 8, first bolt hole; 9, second bolt hole; 10, third bolt hole; 11, fourth bolt hole; 12, fifth bolt hole; 13, sixth bolt hole; 14, seventh bolt hole; 15, eighth bolt hole; 16, ninth bolt hole; 17, tenth bolt hole; 18, eleventh bolt hole; 19, twelfth bolt hole; 20, first upper counterweight block through hole; 21, second upper counterweight block through hole; 22, third upper counterweight block through hole; 23, fourth upper counterweight block through hole; 24, fifth upper counterweight block through hole; 25, sixth upper counterweight block through hole; 26, seventh upper counterweight block through hole; 27, eighth upper counterweight block through hole; 28, first lower counterweight block through hole; 29, second lower counterweight block through hole; 30, third lower counterweight block through hole; 31, fourth lower counterweight block through hole; 32, fifth lower counterweight block through hole; 33, sixth lower counterweight block through hole; 34, seventh lower counterweight block through hole; 35, eighth lower counterweight block through hole. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0027] The fixture device structure of the present application is shown in Figure 1 The fixture device includes the mesa adapter section 1, the compression nut 2, the test piece spur gear 3, the counterweight bolt 4, the counterweight nut 5, the upper counterweight block 6 and the lower counterweight block 7.

[0028] The mesa adapter section 1 has 12 bolt holes, i.e., the first bolt hole 8, the second bolt hole 9, the third bolt hole 10, the fourth bolt hole 11, the fifth bolt hole 12, the sixth bolt hole 13, the seventh bolt hole 14, the eighth bolt hole 15, the ninth bolt hole 16, the tenth bolt hole 17, the eleventh bolt hole 18 and the twelfth bolt hole 19.

[0029] The mesa adapter section structure of the present application is shown in Figure 2As shown in the drawings, the table adapter 1 is composed of a base and a mounting shaft, and the base is provided with 12 bolt holes, so that the table adapter 1 can be fixed on the vibration table through the 12 bolt holes by bolts; the test piece straight gear 3 is fixed on the mounting shaft of the table adapter 1 through the compression nut 2. The base of the table adapter 1 is a circular table structure, specifically a central symmetric structure, and the center of gravity of the base coincides with the shaft center. The mounting shaft of the table adapter 1 is a stepped cylindrical structure, specifically including a large diameter section in the lower part and a small diameter section in the upper part, and the connecting part of the large diameter section and the small diameter section forms a shaft shoulder structure. The small diameter section includes a light rod section in the lower part and a threaded section in the upper part. The mounting shaft of the table adapter 1 is specifically a central symmetric structure, and the center of gravity of the mounting shaft coincides with the shaft center.

[0030] The first bolt hole 8, the second bolt hole 9, the fourth bolt hole 11, the sixth bolt hole 13, the seventh bolt hole 14, the ninth bolt hole 16, the eleventh bolt hole 18 and the twelfth bolt hole 19 are uniformly distributed on the first circumference of the base along the circumference.

[0031] The third bolt hole 10, the fifth bolt hole 12, the eighth bolt hole 15 and the tenth bolt hole 17 are uniformly distributed on the second circumference of the base along the circumference. The diameter of the first circumference is larger than the diameter of the second circumference.

[0032] The upper counterweight structure of the present application is as shown in the drawings, Figure 3 The upper counterweight 6 has eight through holes, i.e. the first upper counterweight through hole 20, the second upper counterweight through hole 21, the third upper counterweight through hole 22, the fourth upper counterweight through hole 23, the fifth upper counterweight through hole 24, the sixth upper counterweight through hole 25, the seventh upper counterweight through hole 26 and the eighth upper counterweight through hole 27. The upper counterweight 6 has a disc structure, including a thick wall part on the outer side and a thin wall part on the inner side. The eight upper counterweight through holes are uniformly distributed on the thin wall part along the circumference. The upper counterweight 6 is specifically a central symmetric structure, and the center of gravity of the upper counterweight 6 coincides with the shaft center.

[0033] The lower counterweight structure of the present application is as shown in the drawings, Figure 4 The lower counterweight 7 has eight threaded holes, i.e. the first lower counterweight through hole 28, the second lower counterweight through hole 29, the third lower counterweight through hole 30, the fourth lower counterweight through hole 31, the fifth lower counterweight through hole 32, the sixth lower counterweight through hole 33, the seventh lower counterweight through hole 34 and the eighth lower counterweight through hole 35. The lower counterweight 7 has a disc structure, including a thick wall part on the outer side and a thin wall part on the inner side. The eight lower counterweight through holes are uniformly distributed on the thin wall part along the circumference. The lower counterweight 7 is specifically a central symmetric structure, and the center of gravity of the lower counterweight 7 coincides with the shaft center.

[0034] Further, the number of the upper counterweight through holes is the same as that of the lower counterweight through holes, and they are one-to-one corresponding.

[0035] The partial assembly structure of the present application is as shown in the drawings,Figure 5 As shown, the gear edge of the test spur gear 3 is matched with the upper counterweight 6 and the lower counterweight 7, the upper counterweight 6, the test spur gear 3 and the lower counterweight 7 are compressed by the 8 counterweight bolts 4 passing through the 8 upper counterweight through holes of the upper counterweight 6 and the 8 lower counterweight through holes of the lower counterweight 7 and the 8 counterweight nuts 5.

[0036] In addition, the total weight of the counterweight can be flexibly controlled by changing the number of the counterweight bolts 4 and the counterweight nuts 5.

[0037] Based on the above-mentioned high-cycle fatigue test fixture device for the spur gear of an aero-engine, the present application further proposes a method for reducing the gear test pitch circle modal frequency, which uses the above-mentioned gear test fixture device for testing, characterized in that the pitch circle modal frequency of the gear is reduced by counterweighting the gear.

[0038] The test principle of the high-cycle fatigue test of the spur gear of an aero-engine is to press and hold the shaft neck of the spur gear and fix it on the vibration table for high-cycle fatigue test, the test frequency is the pitch circle modal frequency of the spur gear, the spur gear is excited by the vibration table to vibrate at a large amplitude, and a large stress fatigue crack is generated at the most dangerous cross section of the spur gear to obtain the high-cycle fatigue test result of the spur gear. However, since the size of the spur gear of an aero-engine is small, its pitch circle modal frequency is high, and the working frequency range of the vibration table often cannot meet the requirements of the test frequency. Even if the working frequency of the vibration table meets the requirements of the test frequency, the vibration table cannot meet the requirements of the fatigue failure of the spur gear under the maximum thrust, and the vibration table is easily damaged or even destroyed under the working of the maximum thrust for a long time. The high-cycle fatigue test fixture device for the spur gear of an aero-engine designed by the present application reduces the pitch circle modal frequency of the spur gear by counterweighting the spur gear, which can meet the requirements of the high-cycle fatigue test of the spur gear within the working frequency range of the vibration table.

[0039] When the fixture device of the present application is used for testing, the test is carried out at the pitch circle modal frequency of the test spur gear 3, the pitch circle modal frequency of the test spur gear 3 is reduced due to the structure of the counterweight, the working frequency range of the vibration table meets the requirements of the test, in addition, the test spur gear 3 can obtain a larger vibration displacement response and produce fatigue failure under a relatively small output of the vibration table.

[0040] The present invention was applied to high-cycle fatigue testing of a Z8 spur gear on a certain type of aircraft engine. The pitch frequency of this Z8 spur gear exceeded the operating frequency range of a certain vibration table (0-3500Hz). Using the test fixture of the present invention not only reduced the spur gear pitch modal frequency to within the vibration table's operating frequency range, but also improved the vibration displacement response of the test specimen, spur gear 3, during testing. High-cycle fatigue test results for the spur gear were obtained at 60% of the vibration table's maximum thrust. The tests demonstrated that the fixture of the present invention can be used for high-cycle fatigue testing of spur gears on various aircraft engines currently under development.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0043] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gear test fixture device, comprising a tabletop transition section (1), a pressing member (2), and a test piece spur gear (3), wherein the pressing member (2) presses and fixes the test piece spur gear (3) on the tabletop transition section (1), and the tabletop transition section (1) is fixed on a vibration table; characterized in that: A counterweight is fixedly provided on the test piece spur gear (3) in a detachable manner; The counterweight block comprises an upper counterweight block (6) and a lower counterweight block (7), wherein the upper counterweight block (6) and the lower counterweight block (7) are respectively fixed to the upper side and the lower side of the test piece spur gear (3) by clamping; The upper counterweight block (6) has a plurality of upper counterweight block through holes evenly distributed along the circumference; the lower counterweight block (7) has a plurality of lower counterweight block through holes evenly distributed along the circumference; the upper counterweight block through holes are the same in number as the lower counterweight block through holes, and are in one-to-one correspondence; A plurality of counterweight bolts (4) pass through the through hole of the upper counterweight block and the through hole of the lower counterweight block and are compressed by a plurality of counterweight nuts (5), whereby the upper counterweight block (6) and the lower counterweight block (7) clamp the test piece spur gear (3); The upper counterweight (6) has a disc-shaped structure, including a thick-walled portion located on the outside and a thin-walled portion located on the inside; the through holes of the upper counterweight are evenly distributed along the circumference in the thin-walled portion; the upper counterweight (6) is specifically a centrosymmetrical structure, and the center of gravity of the upper counterweight (6) coincides with the axis; The lower counterweight (7) has a disc-shaped structure, including a thick-walled portion located on the outside and a thin-walled portion located on the inside, and the through holes of the lower counterweight are evenly distributed in the thin-walled portion along the circumference; the lower counterweight (7) is specifically a centrosymmetrical structure, and the center of gravity of the lower counterweight (7) coincides with the axis.

2. The gear test fixture device according to claim 1, characterized in that: The tabletop transition section (1) is composed of a base and a mounting shaft. The base is provided with a plurality of bolt holes. A plurality of bolts pass through the plurality of bolt holes to fix the tabletop transition section (1) on the vibration table. The pressing member (2) presses and fixes the test piece spur gear (3) on the mounting shaft of the tabletop transition section (1).

3. The gear test fixture device according to claim 1, characterized in that: The mounting shaft of the tabletop transition section (1) is a stepped cylindrical structure, specifically comprising a large diameter section at the bottom and a small diameter section at the top, wherein a shoulder structure is formed at the connection between the large diameter section and the small diameter section, and the shoulder structure is capable of abutting against the test piece spur gear (3); the small diameter section comprises a polished rod section at the bottom and a threaded section at the top; the mounting shaft of the tabletop transition section (1) is specifically a centrosymmetrical structure, and the center of gravity of the mounting shaft coincides with the axis center.

4. The gear test fixture device according to claim 2, characterized in that: The multiple bolt holes are arranged in two groups. The bolt holes in the first group are evenly distributed along the circumference on the first circumference of the base; the bolt holes in the second group are evenly distributed along the circumference on the second circumference of the base, and the diameter of the first circumference is greater than the diameter of the second circumference.

5. A method for reducing the pitch modal frequency of a gear test, wherein the method comprises: By balancing the gear, the pitch modal frequency of the gear is reduced.

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