CN109540458B - Variable mass counterweight in thin tube and mass adjusting method - Google Patents
Variable mass counterweight in thin tube and mass adjusting method Download PDFInfo
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- CN109540458B CN109540458B CN201811289075.0A CN201811289075A CN109540458B CN 109540458 B CN109540458 B CN 109540458B CN 201811289075 A CN201811289075 A CN 201811289075A CN 109540458 B CN109540458 B CN 109540458B
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- counterweight
- thin tube
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- chute
- fixing bolt
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/08—Aerodynamic models
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
- G01M7/02—Vibration-testing by means of a shake table
Abstract
A variable mass counterweight in a thin tube and a mass adjusting method are disclosed, wherein the counterweight comprises a counterweight chute, a plurality of counterweight sheets and a fixing bolt; at least two counterweight chutes are fixed inside the test thin tube; the bottom shape of the counterweight sliding chute is consistent with the shape of the inner wall of the thin tube, and the size of an opening at the upper end of the counterweight sliding chute is smaller than that of the bottom of the same section; the shape of the counterweight plate is consistent with that of the chute, the counterweight plate can be placed into the chute from the side of the counterweight chute, one end of each of two sides of the counterweight chute is provided with a plug, and the other side of the counterweight chute is provided with a fixing bolt hole; fixing bolt screws into the fixing bolt hole, and the counterweight plate placed in the chute is tightly propped by the fixing bolt, so that the counterweight plate and the counterweight chute are fixed with each other.
Description
Technical Field
The invention discloses a variable mass counterweight in a thin tube, belonging to the field of aerospace engineering.
Background
In some dynamic wind tunnel tests, the design model and the design prototype are required to satisfy dynamic similarity, which is usually realized by mass distribution similarity and rigidity distribution similarity. The conventional practice for mass distribution is similar: and (3) obtaining the due mass distribution of the model by utilizing finite element calculation, processing related balance weights, and installing balance weights at different positions of the model to ensure that the mass distribution of the model is similar.
As shown in fig. 1, the conventional model weight system includes: fixing parts such as thin-wall models, balance weights and rivets. Before the laboratory, the balance weight needs to be installed inside the thin-wall model by rivets, and once the balance weight is installed and fixed, the balance weight cannot be detached.
The existing model counterweight has the following problems:
(1) the test design is difficult, because complicated model design work is required, accurate mass distribution of each position on the simplified model can be obtained, and the balance weight is designed by an equivalent method, the design prototype is often difficult to realize to be completely similar in the design process, thereby bringing design errors.
(2) The counterweight mass is not adjustable, once the counterweight and the model are fixed with each other, the counterweight and the model cannot be disassembled, otherwise, the test model is damaged, and even if a fault occurs in design, the design model cannot be modified by changing the mode of counterweight of the model.
(3) Model design errors cannot be avoided, errors generated in the aspects of finite element calculation, machining, installation, design and the like cannot be eliminated, the actual model dynamics characteristics may be greatly different from expectations, and the model cannot be changed even if a problem is found in a design part in the ground process.
(4) The designed balance weight can not be used repeatedly, and the next test still needs to be redesigned, processed and balanced, so that waste is caused to a certain extent.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the defects of the prior art are overcome, the variable mass balance weight in the thin pipe and the mass adjusting method are provided, the balance weight adjustment of the model can be simply and conveniently carried out after a ground test, and therefore the advantages that the model design difficulty is reduced, the model design accuracy rate and the success rate are increased and the like are achieved.
The technical solution of the invention is as follows: a thin tube internal variable mass counterweight comprising: the counterweight chute, a plurality of counterweight plates and a fixing bolt; at least two counterweight chutes are fixed inside the test thin tube; the bottom shape of the counterweight sliding chute is consistent with the shape of the inner wall of the thin tube, and the size of an opening at the upper end of the counterweight sliding chute is smaller than that of the bottom of the same section; the shape of the counterweight plate is consistent with that of the chute, the counterweight plate can be placed into the chute from the side of the counterweight chute, one end of each of two sides of the counterweight chute is provided with a plug, and the other side of the counterweight chute is provided with a fixing bolt hole; fixing bolt screws into the fixing bolt hole, and the counterweight plate placed in the chute is tightly propped by the fixing bolt, so that the counterweight plate and the counterweight chute are fixed with each other.
Preferably, the number of the counterweight sliding chutes is three, and the counterweight sliding chutes are symmetrically fixed in the test thin tube.
Preferably, when the test thin tube is a thin round tube, the section of the counterweight sliding chute is in a fan-ring shape; when the test thin tube is a square tube, the section of the counterweight sliding chute is trapezoidal.
Preferably, when the number of the counterweight chutes is three, if the test thin tube is a circular tube, the central angle corresponding to the fan ring is not greater than 100 °, and if the test thin tube is a square tube, the angle formed by the two side edges of the trapezoid is not greater than 90 °.
Preferably, when there are three counterweight chutes, if the test thin tube is a circular tube, the central angle corresponding to the fan ring is 60 ° to 100 °, and if the test thin tube is a square tube, the angle formed by the two sides of the trapezoid is 60 ° to 80 °.
Preferably, the fixing bolt hole is a semi-closed threaded hole, and the opening angle b of the threaded hole is 120 degrees +/-10 degrees.
Preferably, the density of the counterweight sliding chute, the counterweight plate and the fixing bolt exceeds 15000kg/m3Alloy or metal.
Preferably, the end of the fixing bolt is a flat head.
Preferably, the thickness of the weight plate is between 1mm and 2 mm.
Preferably, the thickness of the plug is optimally 1 mm-2 mm.
A quality adjusting method for a thin pipe is realized by the following steps:
firstly, performing a ground vibration test on the processed test thin tube to obtain the vibration frequency of the test thin tube;
secondly, comparing the obtained vibration frequency with a corresponding design target frequency, and reducing the weight plates if the vibration frequency is lower than the design target frequency; if the vibration frequency is higher than the design target frequency, adding the counterweight plates; otherwise, the number of the current counterweight plates is not changed; restarting the execution from the first step; executing the third step until the vibration frequency obtained by the test and the design target frequency reach the preset precision requirement;
thirdly, continuing to perform a ground vibration test to obtain the vibration mode of the test thin tube, and turning to the fourth step;
and fourthly, judging according to the vibration mode, if the amplitude of the local position is higher than the design target, adjusting the counterweight plate corresponding to the local position to a position with the amplitude lower than the design target, and turning to the third step until the vibration mode meets the requirement.
Preferably, in the second step, the number of weight plates is adjusted according to the principle that the frequency is proportional to the square of the mass.
Compared with the prior art, the invention has the beneficial effects that:
(1) the fault tolerance of model design is higher, and the traditional test method usually requires the model design to be in place once, must all keep accurate on all aspects of precision, and has great requirements on the model design. The structure and the method shown by the invention can also adjust through the adjustment of the balance weight in the test process even if the design deviation occurs in the initial design stage of the model, thereby increasing the opportunity of model modification and model adjustment and greatly reducing the difficulty of model design.
(2) The model and the model designed by calculation often have deviation in the design and processing process, and under the previous condition, the design deviation can not be adjusted, so that the accuracy of the model test is influenced. The model can be adjusted by adjusting the balance weight, so that model design errors caused by factors such as processing, installation and the like are reduced or even eliminated, the model accuracy is higher, and the corresponding test result is more accurate.
(3) Compared with the traditional disposable balance weight, the adjustable balance weight designed by the invention can be used for disassembling parts such as a relevant model balance weight sheet, a fixing bolt and the like after the test is finished, and the test part can be used repeatedly, so that the test cost can be reduced to a certain extent.
Drawings
FIG. 1 is an isometric view of a prior art counterweight structure;
FIG. 2 is an isometric view of a variable mass counterweight of the present invention;
FIG. 3 is a cross-sectional view of a variable mass counterweight of the present invention;
FIG. 4 is a top view of the variable mass counterweight of the present invention;
FIG. 5 is a schematic view of the shape of a weight plate of the present invention;
FIG. 6 is an assembly view of the variable mass counterweight of the present invention;
FIG. 7 is a schematic diagram of a target mode shape designed and a mode shape obtained by an actual test;
1 thin-wall model, 2 traditional counterweights, 3 rivets, 4 counterweight chutes, 5 counterweight sheets and 6 fixing bolts.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
As shown in fig. 6, the present invention includes: thin wall model 1, rivet 3, counter weight spout 4, counter weight piece 5, fixing bolt 6.
Wherein, a counterweight chute 4 is fixed inside the thin-wall model 1 by using a rivet 3; in this example, the number of the counterweight chutes 4 is three; the bottom shape of the counterweight sliding chute is consistent with the shape of the inner wall of the thin tube, and the size of an opening at the upper end of the counterweight sliding chute is smaller than that of the bottom of the same section; for example, when the thin tube is a thin circular tube, the shape of the bottom of the counterweight sliding chute is as shown in fig. 2 and 3, the shape of the cross section of the counterweight sliding chute is a fan-shaped ring, the central angle a corresponding to the fan-shaped ring is not more than 100 degrees, and the optimal value range is 60-100 degrees. When the test thin tube is a square tube, the section of the counterweight chute is trapezoidal, the angle formed by two side edges of the trapezoid is not more than 90 degrees, and the optimal value range is 60-80 degrees. The shape of the counterweight plate 5 is consistent with that of the chute 4, as shown in fig. 5, the counterweight plate can be placed into the chute from the side of the counterweight chute 4, one end of each of two sides of the counterweight chute is provided with a plug, and the other side of the counterweight chute is provided with a fixing bolt hole; fixing bolt 6 screws into the fixing bolt hole, and the counterweight plate placed in the chute is tightly propped by the fixing bolt, so that the counterweight plate and the counterweight chute are fixed with each other. The thickness of the counterweight plate is between 1mm and 2mm, and the optimal value of the thickness of the plug is 1mm to 2 mm.
As shown in fig. 4, the fixing bolt hole is a semi-closed threaded hole, and the opening angle b of the threaded hole is 120 ° ± 10 °. The density of the counterweight sliding chute, the counterweight plate and the fixing bolt exceeds 15000kg/m3Alloy or metal. The fixing bolt end is preferably a flat head.
As shown in fig. 6, the counterweight chute 4 is placed at a corresponding position inside the thin-wall model 1, and the counterweight chute and the thin-wall model are fixed with each other by using a rivet 3; in the test process, a certain amount of counterweight plates 5 are placed in the counterweight sliding grooves 4 and are compressed and fixed by using fixing bolts 6; if the model counterweight needs to be changed, the fixing bolt 6 is screwed out, and a certain number of counterweight plates 5 are taken out/added. The specific adjustment is processed according to the following steps:
firstly, performing a ground vibration test on the processed test thin tube to obtain the vibration frequency of the test thin tube;
secondly, comparing the obtained vibration frequency with a corresponding design target frequency, and reducing the weight plates if the vibration frequency is lower than the design target frequency; if the vibration frequency is higher than the design target frequency, adding the counterweight plates; otherwise, the number of the current counterweight plates is not changed; restarting the execution from the first step; executing the third step until the vibration frequency obtained by the test and the design target frequency reach the preset precision requirement; the adjustment of the weight plates is optimally adjusted according to the principle that the frequency is proportional to the square of the mass. For example, after model design, in a ground experiment process, as shown in fig. 7, where a dotted line is a design target mode shape and an actual test result mode shape is implemented, it can be seen that the vibration amplitude is larger at the rear box position and smaller at the front position. The rear counterweight can be appropriately reduced and adjusted forward.
Thirdly, continuing to perform a ground vibration test to obtain the vibration mode of the test thin tube, and turning to the fourth step;
and fourthly, judging according to the vibration mode, if the amplitude of the local position is higher than the design target, adjusting the counterweight plate corresponding to the local position to a position with the amplitude lower than the design target, and turning to the third step until the vibration mode meets the requirement.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications, equivalent variations and modifications made to the above embodiment according to the technical spirit of the present invention still fall within the scope of the technical solution of the present invention.
The invention has not been described in detail in part of the common general knowledge of those skilled in the art.
Claims (12)
1. A variable mass counterweight structure inside a thin tube, characterized by comprising: the counterweight chute, a plurality of counterweight plates and a fixing bolt; at least two counterweight chutes are fixed inside the test thin tube; the bottom shape of the counterweight sliding chute is consistent with the shape of the inner wall of the thin tube, and the size of an opening at the upper end of the counterweight sliding chute is smaller than that of the bottom of the same section; the shape of the counterweight plate is consistent with that of the counterweight sliding chute, the counterweight plate can be placed into the sliding chute from the side of the counterweight sliding chute, one end of each of two sides of the counterweight sliding chute is provided with a plug, and the other side of each counterweight sliding chute is provided with a fixing bolt hole; fixing bolt screws into the fixing bolt hole, and the counterweight plate placed in the chute is tightly propped by the fixing bolt, so that the counterweight plate and the counterweight chute are fixed with each other.
2. The thin tube internal variable mass counterweight structure of claim 1, wherein: the number of the counterweight sliding chutes is three, and the counterweight sliding chutes are symmetrically fixed inside the test thin tube.
3. The thin tube internal variable mass counterweight structure of claim 1 or 2, wherein: when the test thin tube is a thin round tube, the section of the counterweight sliding chute is in a fan-ring shape; when the test thin tube is a square tube, the section of the counterweight sliding chute is trapezoidal.
4. The thin tube internal variable mass counterweight structure of claim 3, wherein: when the number of the counterweight chutes is three, if the test thin tube is a round tube, the central angle corresponding to the fan ring is not more than 100 degrees, and if the test thin tube is a square tube, the angle formed by the two side edges of the trapezoid is not more than 90 degrees.
5. The thin tube internal variable mass counterweight structure of claim 4, wherein: when the number of the counterweight chutes is three, if the test thin tube is a circular tube, the central angle corresponding to the fan ring is 60-100 degrees, and if the test thin tube is a square tube, the angle formed by the two side edges of the trapezoid is 60-80 degrees.
6. The thin tube internal variable mass counterweight structure of claim 1, wherein: the fixing bolt hole is a semi-closed threaded hole, and the opening angle b of the threaded hole is 120 degrees +/-10 degrees.
7. The thin tube internal variable mass counterweight structure of claim 1, wherein: the density of the counterweight sliding chute, the counterweight plate and the fixing bolt exceeds 15000kg/m3And (5) manufacturing metal.
8. The thin tube internal variable mass counterweight structure of claim 1, wherein: the end part of the fixing bolt is a flat head.
9. The thin tube internal variable mass counterweight structure of claim 1, wherein: the thickness of the counterweight plate is 1 mm-2 mm.
10. The thin tube internal variable mass counterweight structure of claim 1, wherein: the thickness of the plug ranges from 1mm to 2 mm.
11. A method for adjusting the quality of a thin pipe is characterized by comprising the following steps:
firstly, performing a ground vibration test on the processed test thin tube to obtain the vibration frequency of the test thin tube;
secondly, comparing the obtained vibration frequency with a corresponding design target frequency, and if the vibration frequency is lower than the design target frequency, reducing the counterweight sheets by using the counterweight structure of claim 1; if the vibration frequency is higher than the design target frequency, adding a weight plate by using the weight structure of claim 1; otherwise, the number of the current counterweight plates is not changed; restarting the execution from the first step; executing the third step until the vibration frequency obtained by the test and the design target frequency reach the preset precision requirement;
thirdly, continuing to perform a ground vibration test to obtain the vibration mode of the test thin tube, and turning to the fourth step;
and fourthly, judging according to the vibration mode, if the amplitude of the local position is higher than the design target, adjusting the counterweight plate corresponding to the local position to a position with the amplitude lower than the design target, and turning to the third step until the vibration mode meets the requirement.
12. The method of claim 11, wherein: in the second step, the number of the weight plates is adjusted according to the principle that the frequency is in direct proportion to the square of the mass.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811289075.0A CN109540458B (en) | 2018-10-31 | 2018-10-31 | Variable mass counterweight in thin tube and mass adjusting method |
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| CN201811289075.0A CN109540458B (en) | 2018-10-31 | 2018-10-31 | Variable mass counterweight in thin tube and mass adjusting method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE4311936A1 (en) * | 1993-04-10 | 1993-10-07 | J M Voith Ag St Poelten | Balancing weight positioning system for roller, drum or cylinder casing - using hard positioning pins with pointed ends for penetrating material of cylinder inside wall around central support. |
| EP1184590B1 (en) * | 2000-08-10 | 2005-11-30 | Heidelberger Druckmaschinen Aktiengesellschaft | Procedure and apparatus for balancing a rotating body |
| JP2006090739A (en) * | 2004-09-21 | 2006-04-06 | Toyota Motor Corp | Balancing structure for rotor |
| KR100672339B1 (en) * | 2006-03-29 | 2007-01-24 | 엘지전자 주식회사 | Drum of drum type washing machine |
| CN204027769U (en) * | 2014-08-17 | 2014-12-17 | 中国航空工业集团公司沈阳发动机设计研究所 | A kind of rotor balancing balance weight mechanism |
| CN204605030U (en) * | 2015-04-13 | 2015-09-02 | 南通海国机械有限公司 | A kind of nipper cylinder |
| US10436224B2 (en) * | 2016-04-01 | 2019-10-08 | General Electric Company | Method and apparatus for balancing a rotor |
| US9772004B1 (en) * | 2016-06-20 | 2017-09-26 | American Axle & Manufacturing, Inc. | Shaft assembly with balance weight bonded to shaft member |
| CN205950447U (en) * | 2016-08-24 | 2017-02-15 | 温州市永耀水晶设备制造有限公司 | Rhinestone grinding and polishing machine's cylinder dynamic balance adjustment mechanism |
| CN207652216U (en) * | 2017-12-28 | 2018-07-24 | 杭州奇虎节能技术有限公司 | A kind of the high-precision counter weight construction and p-m rotor of p-m rotor |
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