CN105118358A - Motion mathematic model of balance-amplification mechanism for precision balance - Google Patents
Motion mathematic model of balance-amplification mechanism for precision balance Download PDFInfo
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- CN105118358A CN105118358A CN201510603798.3A CN201510603798A CN105118358A CN 105118358 A CN105118358 A CN 105118358A CN 201510603798 A CN201510603798 A CN 201510603798A CN 105118358 A CN105118358 A CN 105118358A
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- balance
- flexible hinge
- enlarger
- precision
- motion
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Abstract
The invention discloses a motion mathematic model of a balance-amplification mechanism for a precision balance. The motion mathematic model comprises a flexible hinge parallel four-rod mechanism, a lever mechanism, a string draw mechanism and a supporting mechanism, which all form an integral molded rigid body. The flexible hinge parallel four-rod mechanism includes flexible hinges. The lever mechanism includes flexible hinges and rigid bodies at two sides of the hinges. The string draw mechanism includes flexible hinges and corresponding rigid bodes between the hinges. The approximation mathematic model of the motion model, containing parameters such as K1, K2, K3, l, x and y, is shown in the description. To-be-tested force F is forced applied to one end portion of the flexible hinge parallel four-rod mechanism, and D is displacement of the lever mechanism relative to the other end of the flexible hinge parallel four-rod mechanism when the to-be-tested force F generates gravity at the minimum precision quality. The beneficial effects of the invention are that the motion mathematic model of a balance-amplification mechanism is provided for the design of balances that need different precision requirements, a convenient approach is provided for research and development of a precision balance, the research and development time is saved, and the research and development cost is reduced.
Description
Technical field
The present invention relates to a kind of precision balance, particularly relate to one
for the motion mathematical model of the balance-enlarger of precision balance.
Background technology
Along with the progress of science and technology and the raising of manufacturing technology level; the requirement of every profession and trade to high-precision weighing improves constantly; such as in the field such as biomedical engineering and bio-pharmaceuticals; often can run into Tiny Mass analysis; at chemical field; the quality of the accurate reactant of frequent needs, in the industrial production, also usually needs the quality of exact material.For the manufacture of precision balance, it is conventional method that lever balance-amplifying method is weighed, and such as publication number is that the application for a patent for invention of CN104374451A discloses a kind of monomer sensor physical construction for weighing.But the method for designing of used balance-enlarger of weighing for lever balance-amplifying method, temporarily also finds no concrete theory and is described and instructs with clear and definite method for designing.Therefore, the method for designing of applicant to the balance-enlarger of precision balance is studied.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of convenient way developing precision balance balance-enlarger motion mathematical model used.
The technical solution adopted in the present invention is: a kind of
for the motion mathematical model of the balance-enlarger of precision balancecomprise: be integrally formed the flexible hinge parallelogram lindage of shaping rigid body, leverage, strap mechanism and supporting mechanism, described flexible hinge parallelogram lindage comprises flexible hinge, described leverage comprises flexible hinge and this hinge both sides rigid body, described strap mechanism comprises corresponding rigid body between flexible hinge and hinge, and the mathematical model of this motion model is:
Parameter in formula: K
1for the rotational stiffness of flexible hinge, K
2for the rotational stiffness of flexible hinge, K
3for the rotational stiffness of flexible hinge, l is the length of flexible hinge parallelogram lindage, x, y are the length of leverage fulcrum hinge left and right rigid body portion, be an end applied force on flexible hinge parallelogram lindage by dynamometry F, D be by dynamometry F be minimum precision quality produce gravity time the leverage displacement that produces relative to the flexible hinge parallelogram lindage other end.
The maximal value of described parameter l is got and is taken as the balance-height of enlarger headspace and 2/3rds of length respectively, and the maximal value of described parameter x and y is taken as the balance-height of enlarger headspace and 3/4ths of length.
In the scope that described parameter values meets the demands, when optimal value is the gravity applying to be produced by the quality that dynamometry F is measuring accuracy, D value can be made to be the parameter value of maximal value.
Described measurement resolution is the balance of 10mg-0.01mg.
Balance-the enlarger of described precision balance also comprises governor motion, and this mechanism can be provided with adjustment hole, and described adjustment hole is positioned in the symmetrical center line of flexible hinge.
Also comprise position-limit mechanism, the block that one end that described stop means is included in described leverage is arranged, the spacing rigid body of machine-shaping on supporting mechanism.
The invention has the beneficial effects as follows: the balance design required for different accuracy, give the motion mathematical model of balance-enlarger, the research and development for precision balance provide approach easily, save the research and development time, have saved R&D costs.
Accompanying drawing explanation
fig. 1it is the one-piece construction signal of parallel four-bar flexure hinge mechanism of the present invention, leverage and strap mechanism
figure;
fig. 2it is the structural representation of parallel four-bar flexure hinge mechanism
figure;
fig. 3it is the structural representation of leverage
figure;
fig. 4it is the structural representation of strap mechanism
figure;
fig. 5it is the design parameter signal of a kind of balance-enlarger that the present invention relates to
figure;
fig. 6it is the solid signal of balance-enlarger
figure;
fig. 7it is balance design flow process of the present invention
figure.
Embodiment
Below in conjunction with
accompanying drawingwith embodiment, the present invention is described in further detail:
as Fig. 1shown in, the conventional ultimate principle of precision balance is that lever balance-amplifying method is weighed, namely by exerted forces F
blever balance is passed through with the gravity F of measured object, when initial position reaches equilibrium state, the quality of measured object can be tried to achieve by the size and known lever ratio measuring exerted forces, common embodiment is for adopting Photoelectric Detection location method, utilize feedback of electromagnetic force to balance zero-method principle, realize the weighing to weighed object quality.Before loading, balanced controls are in initial equilibrium conditions.After loading, the quality being weighed object is subjected to displacement by the moving part of balance-enlarger, and the size of displacement is directly proportional to the photocurrent of photoelectric sensor, and photo-signal is converted to voltage signal through photoelectric detective circuit.Voltage signal is regulated by PID, an electric current be directly proportional to the quality m of weighed object is provided to solenoid, coil is under the magnetic fields of magnetic cylinder permanent magnet, power F upwards will be produced, the moving part of electromagnetic force equilibrium mechanism is moved up, the output voltage of photoelectric detective circuit is reduced, and PID integral element makes the electric current of flowing through coil continue to increase, until moving part returns to the position of initial balance.Now, the power F that produces under permanent magnet magnetic field action of coil current
ythe gravity produced with the quality being weighed object is by lever balance, and sensor is in equilibrium state.The quality of weighed object can be obtained by the size and lever ratio detecting equilibrium state lower coil electric current.
Balance-the enlarger of precision balance is a kind of Primary Component realizing precision balance,
fig. 2it is the structural representation of parallel four-bar flexure hinge mechanism
figure,
fig. 3it is the structural representation of leverage
figure,
fig. 4it is the structural representation of strap mechanism
figure,
fig. 6it is the solid signal of balance-enlarger
figure.The structure of balance-enlarger involved in the present invention for be formed with flexible hinge parallelogram lindage, leverage, strap mechanism and other practical mechanisms on rigid body.Wherein flexible hinge parallelogram lindage is made up of flexible hinge 1,2,3,4,5,6,7,8 and corresponding rigid body, leverage is made up of the corresponding rigid body of flexible hinge 11 and both sides thereof, strap mechanism is made up of the corresponding rigid body between flexible hinge 9,10 and flexible hinge 9,10, and the geometric parameter of this model is: l is
as Fig. 5the length of shown flexible hinge parallelogram lindage, a is
as Fig. 5the length of shown strap mechanism, x, y are
as Fig. 5the length of shown leverage fulcrum hinge left and right rigid body portion.For the motion model of this mechanism, set up and have the mathematical motion model of this mechanism to be:
In formula, K
1for the rotational stiffness of flexible hinge 1,2,3,4,5,6,7,8, K
2for the rotational stiffness of flexible hinge 9,10, K
3for the rotational stiffness of flexible hinge 11, all the other each parameters
as schemedshow, a is the length of strap mechanism, and a is building
vertical publicin the process of formula, due to minimum on the impact of D, can ignore, in actual applications, the value of a being exhausted may be large, and F is
as Fig. 1shown applied force on flexible hinge parallelogram lindage, D is when being the gravity of minimum precision quality generation by dynamometry F, the displacement that leverage right-hand member produces.
On the basis of above electronic balance principle, to the embodiment of the design of precision electronic balance be: first according to the demand analysis of the balance of required manufacture, determine the size of the accuracy class that reaches and the device such as the equipment size in analyzing according to demand and all the other circuit boards needed for the balance that designs, estimate the scope of the volumetric parameter of this sensor, next determines the external condition that balance is relevant to balance-enlarger, comprise and determine that the dimensional parameters of this balance-each flexible hinge of enlarger that can process is to estimate the rotational stiffness K of each flexible hinge according to processing conditions and feed order
1, K
2and K
3value.Simultaneously also balance-amplify the full accuracy of position according to institute of the signal parameter analysis location mechanism energy stabilizing determination of adopted photoelectric sensor location mechanism.
Then, the ratio of the gravity that the quality of the power that the minimum current value that can detect according to metering circuit can occur and minimum weighing precision produces determines the scope of the lever ratio x/y of this balance-enlarger, measuring accuracy is reached in order to balance can be made, known, the ratio of the gravity that the quality that the scope of lever ratio x/y should be greater than minimum precision produces and the power that minimum current value can occur.According to balance-enlarger take up space and choose l large as far as possible, the value of a, during value should according to this structure take up space and choose as far as possible large but be less than the value of l, then according to x, y value that motion mathematical model is selected lever ratio scope to meet D value to be greater than location mechanism full accuracy distance.As the value of qualified balance-enlarger can not be selected, then can improve the precision of location mechanism, or after the precision of raising metering circuit, re-start Selecting parameter, until suitable parameter can be selected.
Need set during design by dynamometry F the gravity that produces by the quality under this accuracy class, F as the resolving power balance that is 1mg should be 1mg quality the gravity that produces, this value is about 0.000001N, the F of the balance that resolving power is 0.1mg should be the gravity that 0.1mg quality produces, and this value is about 0.0000001N; D is under this F effect, and the displacement of the right side generation of balance-enlarger leverage, the size of this value is relevant with the geometric parameter of balance-enlarger, and can be tried to achieve by the mathematical model of balance-enlarger, this value need be greater than the resolving power of location mechanism.
Embodiment:
as Fig. 7shown in, with precision be 1 milligram, the example that is designed to of the maximum range lab scale that is 200g sets forth the specific embodiment of the present invention:
According to claim 4 and 5, first determine the scope of lever when x/y, at this, we use electric current and electromagnet as power generating means, now, the current detection accuracy of circuit board is 100nA, the power that this electric current can occur is 10E-6N, the gravity of 1 milligram of weight generation is by dynamometry, this value size is 10E-5N, and therefore the value of x/y should be greater than 1/10, and power generating mechanism can stablize the maximum, force produced simultaneously is 0.5N, simultaneously the gravity that produces of the quality of maximum range 200g is for being 2N by dynamometry, and therefore the value of x/y should be less than 1/4.Consider portability, the internal volume length of designed lab scale is within 50cm, width is within 30cm, highly within 8cm, owing to considering that inside also needs to place circuit board, the parts such as protective cover, therefore planning balancing-space of enlarger is long 12cm, wide 9cm, the rectangular parallelepiped space of high 6cm, because of
this hereinthe maximal value of getting dimensional parameters l and a is respectively long and high 2/3rds, is 8cm and 4cm, x and y's and be 9cm.Consider working ability and cost, the straight round flexible hinge of the hinge of parallel four-bar flexure hinge mechanism to be t=0.1mm radius be R=0.9mm width b=18mm, its rotational stiffness is K
1=0.3N.m/rad; The straight round flexible hinge of definition E, F flexible hinge to be minimum thickness t=0.1mm radius be R=0.9mm width b=12mm, its rotational stiffness is K
2=0.2N.m/rad; Definition fulcrum hinge G is minimum thickness t=0.1mm radius is R=0.9mm, and the straight round flexible hinge of width b=18mm, its rotational stiffness is K
3=0.3N.m/rad.The precision of photoelectricity location mechanism is now 100nm, the value of the displacement D that the power that it is 10E-5N that the value of x and y now not in existence range makes by dynamometry produces is greater than 100nm, therefore the precision improving photoelectricity location mechanism is needed, use device that photoelectricity location precision is 10nm from newly designing at this, after the photoelectricity location mechanism using higher standard, the value of the displacement D that the power that it is 10E-5N that the value that there is x and y makes by dynamometry produces is greater than 10nm, therefore the value that there is x and y satisfies condition, the scope of x is less than 6cm for being greater than 0.6cm, because the value of x and y should be greater than 1/10 and be less than 1/4, and x's and y and be 9cm, therefore the span of x is less than 1.8cm for being greater than 0.82cm.The value choosing x and y in order to the optimized design realizing parameter makes equally by value that the displacement D that can produce under the condition of dynamometry is x and y of maximal value.By x's and y be 9cm, K
1, K
2and K
3the condition such as the value mathematical model of bringing balance-enlarger into can obtain the optimal value of the value of x and y, wherein x is 1.8cm, and y is 7.2cm, and the parameters of basic dimensions of this mechanism is to determine.
Finally, after determining above parameters of basic dimensions, in order to ensure the processing of sensor and normal use, also need increase some other practical mechanisms around above parameter, as added governor motion, this mechanism can be arranged to
fig. 6in the form of adjustment hole 12,13, the position of adjustment hole 12,13 is positioned in the symmetrical center line of flexible hinge 5,6.Adjustment hole 12,13 is through hole and rigid structure below hole is provided with threaded hole, conveniently set screw can be installed, the beam at place, hole 12,13 and the distance of rigid structure is below changed by regulating set screw, the balance fine setting of the both sides of Luo Bai Weir mechanism can be realized, make mechanism's leveling to correct mismachining tolerance and rigging error.In addition, also need to arrange required position-limit mechanism in case stop bit moves past cause damage to flexible hinge greatly, as block 14 can be added, above block and below can arrange fixed rigid body 17,18 limit stop motion displacement to limit flexible hinge distortion excessive.In addition, the rigid body supporting construction adding and continue to employ man-hour need be left, and mounting hole is set above assembles use to enable this mechanism, as arranged rigid body 15 so that the solenoid of installing force generating mechanism electromagnetic mechanism, arranging rigid body 16 makes this balance-enlarger can be fixed by mounting screw with balance outer casing base can beat threaded hole below rigid body 16, carrying out balancing-and the assembling of enlarger.
Claims (6)
1. the motion mathematical model for the balance-enlarger of precision balance, comprise: be integrally formed the flexible hinge parallelogram lindage of shaping rigid body, leverage, strap mechanism and supporting mechanism, described flexible hinge parallelogram lindage comprises flexible hinge (1,2,3,4,5,6,7,8), described leverage comprises flexible hinge (11) and this hinge both sides rigid body, described strap mechanism comprises corresponding rigid body between flexible hinge (9,10) and hinge, it is characterized in that: the mathematical model of this motion model is:
Parameter in formula: K
1for the rotational stiffness of flexible hinge (1,2,3,4,5,6,7,8), K
2for the rotational stiffness of flexible hinge (9,10), K
3for the rotational stiffness of flexible hinge (11), l is the length of flexible hinge parallelogram lindage, x, y are the length of leverage fulcrum hinge left and right rigid body portion, be an end applied force on flexible hinge parallelogram lindage by dynamometry F, D be by dynamometry F be minimum precision quality produce gravity time the leverage displacement that produces relative to the flexible hinge parallelogram lindage other end.
2. the motion mathematical model of a kind of balance-enlarger for precision balance according to claim 1, it is characterized in that: the maximal value of described parameter l is got and is taken as the balance-height of enlarger headspace and 2/3rds of length respectively, the maximal value of described parameter x and y is taken as the balance-height of enlarger headspace and 3/4ths of length.
3. the motion mathematical model of a kind of balance-enlarger for precision balance according to claim 1, it is characterized in that: in the scope that described parameter values meets the demands, when optimal value is the gravity applying to be produced by the quality that dynamometry F is measuring accuracy, D value can be made to be the parameter value of maximal value.
4. the motion mathematical model of a kind of balance-enlarger for precision balance according to claim 3, is characterized in that: described measurement resolution is the balance of 10mg-0.01mg.
5. the motion mathematical model of a kind of balance-enlarger for precision balance according to claim 1, it is characterized in that: the balance-enlarger of described precision balance also comprises governor motion, this mechanism can be provided with adjustment hole (12,13), and described adjustment hole (12,13) is positioned in the symmetrical center line of flexible hinge (5,6).
6. the motion mathematical model of a kind of balance-enlarger for precision balance according to claim 1, it is characterized in that: also comprise position-limit mechanism, the block (14) that one end that described stop means is included in described leverage is arranged, the spacing rigid body (17,18) of machine-shaping on supporting mechanism.
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| CN201510603798.3A CN105118358B (en) | 2015-09-20 | 2015-09-20 | Precision balance balance-enlarger with motion mathematical model |
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| CN201510603798.3A CN105118358B (en) | 2015-09-20 | 2015-09-20 | Precision balance balance-enlarger with motion mathematical model |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105738467A (en) * | 2016-02-04 | 2016-07-06 | 天津大学 | Magnetic memory multi-lift-off value pipeline internal detection system and detection method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0706035A2 (en) * | 1994-10-05 | 1996-04-10 | Shimadzu Corporation | Top pan balance |
| CN104374451A (en) * | 2014-11-14 | 2015-02-25 | 天津大学 | Single sensor mechanical structure for weighing |
-
2015
- 2015-09-20 CN CN201510603798.3A patent/CN105118358B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0706035A2 (en) * | 1994-10-05 | 1996-04-10 | Shimadzu Corporation | Top pan balance |
| CN104374451A (en) * | 2014-11-14 | 2015-02-25 | 天津大学 | Single sensor mechanical structure for weighing |
Non-Patent Citations (3)
| Title |
|---|
| 张霖等: "《单平行四杆柔性铰链机构刚度特性分析》", 《华东交通大学学报》 * |
| 曲彬: "《柔性平行导向机构静动力学分析与优化设计研究》", 《中国优秀硕士学位论文数据库》 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105738467A (en) * | 2016-02-04 | 2016-07-06 | 天津大学 | Magnetic memory multi-lift-off value pipeline internal detection system and detection method thereof |
| CN105738467B (en) * | 2016-02-04 | 2019-04-30 | 天津大学 | Magnetic memory multi-lift-off value pipeline internal detection system and detection method thereof |
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| CN105118358B (en) | 2018-11-27 |
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Granted publication date: 20181127 Termination date: 20190920 |