CN107655931B - High-precision barrel linear expansion coefficient measuring device and method - Google Patents
High-precision barrel linear expansion coefficient measuring device and method Download PDFInfo
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- CN107655931B CN107655931B CN201710675747.0A CN201710675747A CN107655931B CN 107655931 B CN107655931 B CN 107655931B CN 201710675747 A CN201710675747 A CN 201710675747A CN 107655931 B CN107655931 B CN 107655931B
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/16—Investigating or analyzing materials by the use of thermal means by investigating thermal coefficient of expansion
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- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
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- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
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Abstract
A high-precision cylinder linear expansion coefficient measuring device and a method thereof comprise a connecting beam splitting prism component (1), a quartz tube component (2), a connecting reflector component (3) and a V-shaped block component (4). The connection beam splitting prism component (1) and the connection reflector component (3) are arranged at two ends of an upper flange and a lower flange of the cylinder body (5) to be measured, the quartz tube component (2) is arranged in a V-shaped groove which is connected with the beam splitting prism component (1) and the connection reflector component (3), and when the temperature changes, the difference between the moving amounts of the measurement reflector and the reference reflector represents the difference between the length variation of the part to be measured and the length variation of the reference component, namely the reading of the interferometer. The invention can be used for measuring the linear expansion coefficient of the composite material cylinder structure, and can also be used for adaptively changing the linear expansion coefficient of the composite material rod piece and the truss structure. The measuring device has the characteristics of less equipment requirements, simplicity and convenience in use, strong environmental adaptability, high efficiency and high precision.
Description
Technical Field
The invention relates to a high-precision measuring method for the linear expansion coefficient of a cylinder, in particular to a simple device and a simple method for testing the linear expansion coefficient of a composite material cylinder of a space camera.
Background
The space flight high-resolution camera mostly adopts the cylinder as a supporting structure, and the interval change among all optical parts caused by temperature is determined by the linear expansion coefficient of the cylinder, so the cylinder for the space flight high-resolution camera has the characteristic of small temperature linear expansion coefficient. The carbon silicon carbide (C/SiC) material is a novel composite material developed in recent years, has the characteristics of better thermal stability, higher specific stiffness, light weight and the like, and becomes a preferred material of a space high-resolution camera. However, the carbon silicon carbide (C/SiC) cylinder body is formed by reinforcing carbon fiber three-dimensional woven silicon carbide, the linear expansion coefficient of the carbon silicon carbide (C/SiC) cylinder body is greatly different from that of the carbon fiber, and the linear expansion coefficients of the carbon silicon carbide (C/SiC) cylinder body in three directions are different. In order to ensure that the linear expansion coefficient of the cylinder as a key performance index meets the use requirement, the linear expansion coefficient within the use range is accurately measured, and the key point of the measurement is to measure the small variation of the length of the cylinder caused by the temperature change, and the traditional measurement method has the defects of low measurement accuracy, large device and the like.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method is combined with the principle of interference length measurement, utilizes a contrast measurement method to design a symmetrical measurement light path, eliminates the influence of other factors on the test, ensures the test precision, and provides a method for measuring the linear expansion coefficient of the structure, which is simple and convenient to operate, universal and accurate.
The technical solution of the present invention is realized by the following technical scheme: a high-precision barrel linear expansion coefficient measuring device comprises a connecting beam splitting prism component (1), a quartz tube component (2), a connecting reflecting mirror component (3) and a V-shaped block component (4),
an upper flange and a lower flange are arranged at the two ends of the cylinder body (5) to be measured,
the position and the connection relation of each part are as follows: the connecting beam splitting prism component (1) and the connecting reflector component (3) are arranged at two ends of an upper flange and a lower flange of the cylinder body (5) to be measured, and after the connecting beam splitting prism component (1) and the connecting reflector component (3) are arranged on the cylinder body (5) to be measured, V-shaped grooves are arranged on two opposite surfaces of the connecting beam splitting prism component (1) and the connecting reflector component (3),
two ends of the quartz tube component (2) are respectively arranged in V-shaped grooves in the connecting beam splitting prism component (1) and the connecting reflecting mirror component (3);
a cylinder (5) to be measured is arranged on the V-shaped block assembly (4), the V-shaped block assembly (4) is adjusted to enable the central axis of the cylinder (5) to be horizontal relative to a ground plane, and the relative position relation of the connecting beam splitting prism assembly (1), the quartz tube assembly (2) and the connecting reflector assembly (3) is adjusted to enable an interferometer arranged on the other side of the connecting beam splitting prism assembly (1) to receive the signal which enters the interferometer after being incident from the connecting beam splitting prism assembly (1) and reflected by the connecting reflector assembly (3) to be the maximum;
the device needs to record the length variation of the cylinder (5) to be measured at different temperatures by the interferometer under the condition of temperature control, and finally calculates the linear expansion coefficient of the cylinder (5) to be measured according to the length variation at different temperatures.
The connecting beam splitting prism component (1) comprises a beam splitting prism component (11), a beam splitting prism connecting piece A (12) and a beam splitting prism connecting piece B (13);
the beam splitting prism component (11) and the beam splitting prism connecting piece A (12) are both connected with a beam splitting prism connecting piece B (13), the beam splitting prism connecting piece B (13) is connected with one end of the cylinder body (5) to be tested through a flange, and a V-shaped groove is formed in the beam splitting prism connecting piece A (12);
as shown in fig. 4, the beam splitting prism assembly (11) includes a polarization beam splitting assembly (111), a beam splitting prism mirror chamber (112), a beam splitting prism left cover (113), and a beam splitting prism right cover (114);
the polarization beam splitting component (111) is arranged in the beam splitting prism mirror chamber (112), and the polarization beam splitting component (111) is covered by the beam splitting prism left cover (113) and the beam splitting prism right cover (114) together to play a role in protection;
the polarization light splitting component (111) comprises four prisms, a reflecting mirror 1, a spectroscope 2 and a reflecting mirror 2 are sequentially arranged from top to bottom, the spectroscope 1 and the spectroscope 2 are combined into a square, and the junction of the spectroscope 1 and the spectroscope 2 is a bonding surface of the spectroscope 1 and the spectroscope 2;
laser beams enter from the spectroscope 1, a part of light is transmitted to the connecting reflection mirror assembly (3) through the bonding surface of the spectroscope 1 and the spectroscope 2, is reflected by the connecting reflection mirror assembly (3), enters the spectroscope 2, is reflected to the reflection mirror 2 through the bonding surface of the spectroscope 1 and the spectroscope 2, is reflected by the reflection mirror 2, is transmitted to the reflection mirror 1 through the spectroscope 1 and the spectroscope 2, is reflected to the connecting reflection mirror assembly (3) through the reflection mirror 1, enters the reflection mirror 1 after being reflected by the connecting reflection mirror assembly (3), is reflected by the reflection mirror 1, enters the spectroscope 1, is reflected through the bonding surface of the spectroscope 1 and the spectroscope 2, exits from the spectroscope 1, and emergent light and incident light of the spectroscope 1 are parallel.
The quartz tube assembly (2) comprises a quartz tube (21), a quartz tube fixing connecting piece (22) and a counterweight (23);
the quartz tube fixing connecting piece (22) is arranged at one end in the quartz tube (21), and the balance weight (23) is connected with the quartz tube fixing connecting piece (22) through a connecting wire;
two ends of a quartz tube (21) are respectively inserted into the V-shaped grooves of the beam splitting prism component (1) and the connecting reflector component (3), and a connecting line of the counterweight (23) passes through the V-shaped groove of the beam splitting prism component (1) and freely hangs beside a cylinder to be measured;
the end face of the quartz tube (21) is tightly attached to the beam splitter prism connecting piece A (12) through the dead weight of the counterweight (23), so that the quartz tube (21) is prevented from rotating after the adjustment of the quartz tube assembly (2) and the connecting reflector assembly (3) is completed.
The connecting mirror assembly (3) comprises: a reflector connector A (31), a quartz tube connector (32), a reflector connector B (33) and a reflector assembly (34); the connecting reflector component (3) is connected with the other flange end face of the cylinder (5) through a reflector connecting piece A (31);
a mirror assembly (34) comprising: a reference mirror assembly (341), a measurement mirror assembly (342) and a mirror connection plate (343); the reflector connecting plate (343) is removable, before the reflector connecting plate (343) is removed, the reference reflector assembly (341) and the measurement reflector assembly (342) are connected through the reflector connecting plate (343); the measurement reflector assembly (342) is connected with the reflector connector A (31) through a reflector connector B (33), and after the reflector connecting plate (343) is removed, the reference reflector assembly (341) is connected with the quartz tube (21) through a quartz tube connector (32);
as shown in fig. 7, the reference mirror assembly (341) includes a reference mirror (3411), a reference mirror cap (3412), and a reference mirror chamber (3413);
the measurement reflector assembly (342) comprises a measurement reflector (3421), a measurement reflector cover (3422) and a measurement reflector chamber (3423);
as shown in fig. 8 and 9, the reference mirror (3411) is installed in the reference mirror chamber (3413), the measurement mirror (3421) is installed in the measurement mirror chamber (3423), the reference mirror cover (3412) covers the reference mirror (3411), and the measurement mirror cover (3422) covers the measurement mirror (3421) for protection;
a V-shaped groove is formed on the reflector connecting piece A (31) and can be inserted into the quartz tube (21);
the V-shaped block assembly (4) comprises a base (41) and a baffle (42), wherein the baffle (42) is installed on the base (41), as shown in figure 10.
The V-shaped block assemblies (4) are four in number and two in number, the flanges on two sides of the cylinder body (5) to be tested are respectively supported, and the cylinder wall is not contacted with the V-shaped block assemblies (4); the base (41) plays a role of supporting the flange, and the baffle (42) plays a limiting role of clamping the flange;
and adjusting the distance of the V-shaped block assemblies (4) supporting the flanges at the two sides of the cylinder body (5) to be measured to level the cylinder body.
The metal structural members in the connecting beam splitting prism component (1) and the connecting reflector component (3) are made of 4J 32.
A high-precision cylinder linear expansion coefficient measuring method comprises the following steps:
(1) calibrating and measuring the linear expansion coefficient of the quartz tube (21);
(2) adjusting the V-shaped block assembly (4) to enable the cylinder (5) to be horizontal, adjusting the relative position relation of the connecting beam splitting prism assembly (1), the quartz tube assembly (2) and the connecting reflector assembly (3), and enabling the signal intensity entering the interferometer after the incident light from the connecting beam splitting prism assembly (1) is reflected by the connecting reflector assembly (3) to be maximum;
(3) and controlling the temperature of the measuring device and the cylinder (5) to be measured, and recording the readings of the interferometer at different temperature moments.
(4) According to the reading delta L of the interferometer, the linear expansion coefficient lambda of the cylinder (5) to be measured is calculatedmThe method comprises the following steps:
calculating the length variation delta L of the quartz tube (21) at different temperature moments through the formula (1)c
ΔLc＝λc·Lc·ΔT (1)
Calculating displacement variation Delta L of the measuring reflector by formula (2)m，
ΔLm＝ΔL+ΔLc(2)
Finally, calculating the linear expansion coefficient lambda of the cylinder (5) to be measured according to the formula (3) and the formula (4)m。
ΔLm＝λm·Lm·ΔT (3)
Wherein: Δ L is the interferometer reading, i.e. the measured mirror displacement variation subtracts the reference mirror displacement variation; Δ LmIn order to measure the displacement variation of the reflector, the length variation of the cylinder (5) to be measured along with the temperature is equal to the length variation of the cylinder to be measured along with the temperature in the test; Δ LcIn order to refer to the displacement variation of the reflector, the length variation of the quartz tube (21) along with the temperature is equal in the test; lambda [ alpha ]mIs the linear expansion coefficient, L, of the cylinder (5) to be measuredmFor the length of the cylinder (5) to be measured, delta T represents the temperature variation, lambdacIs the linear expansion coefficient of the quartz tube (21), is calibrated before the test, LcThe length of the quartz tube (21) participating in the light path, namely the length between the connecting beam splitting prism component (1) and the connecting reflecting mirror component (3), is measured on site according to the construction result of the device.
Compared with the prior art, the invention has the advantages that:
(1) the method adopts the laser interferometry to measure the length change, and has the characteristic of high precision compared with the traditional measuring methods such as a lever amplification method, a dial indicator method and the like;
(2) the method designs a thermal balance interference system consisting of a connecting beam splitting prism component and a connecting reflector component by utilizing a laser interference length measuring principle, so that the influence of external factors on a reference light path and a measuring light path is equal, the influence of environmental change on a measuring result is eliminated, and the accuracy of the measuring result is ensured.
(3) The method utilizes comparison measurement, the principle is clear, simple and easy to implement, the reading variation of the interferometer is only related to the length variation of the two types of comparison, and the test time can be greatly shortened.
(4) The method needs fewer testing tools and equipment, only needs to adaptively change the external installation interfaces of the connecting beam splitting prism assembly and the connecting reflector assembly, can be applied to composite structural members with different shapes, and greatly reduces the testing cost;
(5) the device of the method is mostly built in a conventional screw connection mode and has no precise adjustment in the light path debugging process, and is simple and easy to implement;
drawings
FIG. 1 is a schematic diagram of the device for measuring length by interference;
FIG. 2 is a diagram of a test apparatus;
FIG. 3 is a diagram of a connecting beam splitting prism assembly;
FIG. 4 is a diagram of a beam splitting prism assembly;
FIG. 5 is a diagram of a quartz tube assembly;
FIG. 6 is a view of the connecting mirror assembly;
FIG. 7 is a mirror assembly view;
FIG. 8 is a view of the inner mirror assembly;
FIG. 9 is a view of the outer mirror assembly;
FIG. 10 is a view of a V-block assembly;
Detailed Description
The basic idea of the invention is as follows: a high-precision cylinder linear expansion coefficient measuring device and a method thereof comprise a connecting beam splitting prism component (1), a quartz tube component (2), a connecting reflector component (3) and a V-shaped block component (4). The connection beam splitting prism assembly (1) and the connection reflector assembly (3) are arranged at two ends of an upper flange and a lower flange of a cylinder body (5) to be measured, the quartz tube assembly (2) is arranged in a V-shaped groove of the connection beam splitting prism assembly (1) and the connection reflector assembly (3), one end of the quartz tube assembly is attached to the connection beam splitting prism assembly (1), and the whole assembly is arranged on the V-shaped block assembly (4) and placed in a temperature control box. The linear expansion coefficient of the quartz tube is calibrated in advance before measurement and used as a reference piece with a known linear expansion coefficient during measurement, the device is set up and adjusted by means of an interferometer during measurement, the temperature of the whole assembly is changed, the interferometer records readings at different temperature moments, and finally a measurement result is calculated. The device and the method design a comparison measuring device according to a laser interference length measuring principle, eliminate the influence of the environment on a test result to the maximum extent, and realize the comparison measuring by a reference reflector and a measuring reflector in a spectroscope component and a reflector component, wherein when the temperature changes, the difference of the moving amounts of the measuring reflector and the reference reflector represents the difference of the length variation of a piece to be measured and the reference piece, namely the reading of an interferometer. The invention can be used for measuring the linear expansion coefficient of the composite material cylinder structure, and can also be used for adaptively changing the linear expansion coefficient of the composite material rod piece and the truss structure. The measuring device has the characteristics of less equipment requirements, simplicity and convenience in use, strong environmental adaptability, high efficiency and high precision.
The invention discloses a high-precision cylinder linear expansion coefficient measuring device, which is shown in figure 2: the device comprises a connecting beam splitting prism component, a quartz tube component, a connecting reflecting mirror component and a V-shaped block component. The position and the connection relation of each part are as follows: the connection beam splitting prism assembly and the connection reflector assembly are arranged at two ends of an upper flange and a lower flange of the cylinder to be measured, the quartz tube assembly is arranged in a V-shaped groove in the connection beam splitting prism assembly and the connection reflector assembly, one end of the quartz tube assembly is attached to the connection beam splitting prism assembly, the whole assembly is arranged on the V-shaped block assembly, and the cylinder to be measured and the quartz tube can expand freely when the temperature changes.
As shown in fig. 1, the connecting beam splitting prism assembly includes a beam splitting prism assembly, a beam splitting prism connecting piece a and a beam splitting prism connecting piece B; the light emitted by the interferometer is divided into reflected light and transmitted light after passing through the light splitting prism, and the two lights are reflected by the reference reflecting mirror and the measuring reflecting mirror in the reflecting mirror assembly, pass through the light splitting prism again and finally return to the laser interferometer to form interference. The measurement reflector assembly (342) is connected with the reflector connector A (31) through a reflector connector B (33), and the reference reflector assembly (341) is connected with the quartz tube (21) through a quartz tube connector (32); both are initially positioned by the mirror attachment plate as shown in fig. 3.
During testing, the reflector connecting plate is removed, the temperature of the device is changed, the reference reflector and the measuring reflector can generate displacement along with free expansion of the quartz tube and the cylinder, the difference value of displacement variation of the reference reflector and the measuring reflector is recorded by the interferometer, namely, the reading of the interferometer is obtained, and the measuring result can be calculated according to the test data.
The invention will be further described with reference to the accompanying drawings. A high-precision cylinder linear expansion coefficient measuring device comprises: connect beam splitting prism subassembly (1), quartz capsule subassembly (2), connect reflector assembly (3), V type piece subassembly (4), connect beam splitting prism subassembly (1) and connect reflector assembly (3) and install in the flange both ends about the barrel that awaits measuring (5), quartz capsule subassembly (2) are installed in the V type inslot and one end and are connected beam splitting prism subassembly (1) laminating in connecting beam splitting prism subassembly (1) and connecting reflector assembly (3), whole test assembly installs in V type piece subassembly (4).
V-shaped block assemblies (4) at two ends of an upper flange and a lower flange of a cylinder body (5) are adjusted, the front height and the rear height of the cylinder body (5) are consistent, horizontal bubbles can be used for monitoring in the process, the V-shaped block assemblies (4) are fixed after adjustment, a beam splitting prism assembly (1) and a connecting reflector assembly (3) are installed and connected on the end faces of the upper flange and the lower flange of the cylinder body (5), mounting holes in the upper flange and the lower flange correspond to the mounting holes in the beam splitting prism connecting piece A (12) and the reflector connecting piece A (31), the cylinder body (5) is adjusted to roll, the connecting beam splitting prism assembly (1) and the connecting reflector assembly (3) are located right above the cylinder body (5), horizontal bubbles can be used for monitoring in the process, the beam splitting prism connecting piece A (12) and the reflector.
And (2) installing a quartz tube component (2), enabling the quartz tube (21) to be positioned in V-shaped grooves of the beam splitter prism connecting piece A (12) and the reflector connecting piece A (31), determining the length of the quartz tube (21) according to the length to be measured of an object, generally 10-30 cm longer than the object, and matching the diameter of the quartz tube with the size of the V-shaped grooves of the beam splitter prism connecting piece A (12) and the reflector connecting piece A (31). One end of the quartz tube component (2) is jointed with the beam splitting prism connecting piece A (12) through a counterweight (23), the counterweight (23) is not too light, the weight is 2-5 times of that of the quartz tube (21), as shown in fig. 5, the balance weight (23) is connected to the quartz tube fixing connector (22) by a wire, the quartz tube fixing connecting piece (22) is arranged at one end of the quartz tube (21) in advance through cementing and is aligned with the end face of the quartz tube (21), the other end of the quartz tube fixing connecting piece is connected with a quartz tube connecting piece (32) connected with the reference reflector component (341), the quartz tube connecting piece (32) is of a circular hoop structure and can be hooped with the quartz tube (21), meanwhile, an interface of a reflector connector B (33) is arranged on the quartz tube connector (32), the rotation of the quartz tube connector (32) is adjusted, the reflector connector B (33) of the reference reflector assembly (341) is coaxial with the hole of the quartz tube connector (32), and the quartz tube connector (32) is fixed after adjustment.
The mirror connection plate (343) is removed and the reference mirror assembly (341) and the measurement mirror assembly (342) are made independent. The measurement mirror assembly (342) is fixed on the mirror connector A (31) through the mirror connector B (33), and the reference mirror assembly (341) is fixed on the quartz tube (21) through the mirror connector B (33) and the quartz tube connector (32). The reference mirror assembly (341) and the measurement mirror assembly (342) are each a structure with a rotatable handle, rotation and translation of the assemblies being achieved by rotation of the handle and movement along the axis of the handle.
The reference mirror assembly (341) and the measurement mirror assembly (342) are adjusted by the aid of the interferometer, and the strength of signals received by the interferometer is maximized. The method specifically comprises the following steps: the height and the torsion of the measuring reflector component (342) are adjusted by adjusting the up-and-down movement and the rotation around the self axis of a reflector connecting piece B (33) connected with the measuring reflector component (342), and the pitching of the measuring reflector component (342) is adjusted by adjusting the rotation of a handle of a measuring reflector chamber (3423); the height and the torsion of the reference mirror assembly (341) are adjusted by adjusting the up-and-down movement and the rotation around the self axis of the mirror connector B (33) connected with the reference mirror assembly (341), the pitching of the reference mirror assembly (341) is adjusted by adjusting the rotation of the handle of the reference mirror chamber (3413), and the reference mirror assembly (341) and the measuring mirror assembly (342) are fixed after the adjustment is finished.
After the adjustment of the components is finished, the components are slightly knocked in three directions by using a mallet, so that the assembly stress is removed, and the influence of stress release on the accuracy of the measurement result due to the temperature change in the test process is avoided. Upon completion, the measurement mirror assembly (342) and the reference mirror assembly (341) can be fine tuned based on interferometer signal strength. The length of the quartz tube (21) participating in the light path is measured on site by a meter ruler, namely the distance L from one end of the quartz tube (21) positioned at the beam splitting prism connecting piece A (12) to the handle of the reference reflector mirror chamber (3413)cAnd the distance L between the two ends of the upper flange and the lower flange of the cylinder body (5) is measuredMAnd the average value can be obtained through multiple measurements, and the influence of initial errors is eliminated.
And controlling the temperature of the whole testing assembly, and recording the reading of the interferometer at different temperature moments. The reading, namely the balance moment, ensures that the temperature difference between the axial direction and the circumferential direction of the cylinder (5) is not more than 0.5 ℃, the temperature change in half an hour is not more than 0.5 ℃, the environment has no air flow, and temperature measuring points can be distributed on the circumferential direction and the axial direction of the cylinder (5) to be measured and the axial direction of the quartz tube (21) for judging whether the temperature of the device reaches balance or not. During testing, the room temperature of 20 ℃ is generally taken as the middle zero temperature, the interferometer is cleared at the temperature, the testing temperature range is 20 +/-10 ℃, and the temperature interval is 2-5 ℃ during reading. In order to ensure the accuracy of the test result, each temperature moment is measured at least twice, and each temperature moment is an average value of multiple measurements. The linear expansion coefficient of the cylinder (5) to be tested in any temperature interval can be calculated according to the test result.
The length change of the cylinder (5) causes the front and back movement of the measuring reflector component (342), the length change of the quartz tube (21) causes the front and back movement of the reference reflector component (341), the linear expansion coefficient of the quartz tube (21) is calibrated to be a known quantity, and according to the measuring device and the symmetrical measuring light path characteristics, the difference between the front and back movement quantity of the measuring reflector component (342) and the front and back movement quantity of the reference reflector component (341) is the reading of the interferometer, namely the difference between the light paths of the measuring light path and the difference between the light paths of the reference light path is the variable quantity. According to the testing principle, when the linear expansion coefficients of the cylinder (5) to be tested and the quartz tube (21) are basically close to each other, the reading of the interferometer in the temperature change process is basically close to zero. When the linear expansion coefficient of the cylinder (5) to be measured is larger than that of the quartz tube (21), the temperature is higher than zero, the reading of the interferometer is positive, and the reading of the interferometer is negative. When the linear expansion coefficient of the cylinder (5) to be measured is smaller than that of the quartz tube (21), the reading of the interferometer is negative when the temperature is increased relative to the zero position, and the reading of the interferometer is positive when the temperature is decreased. This principle is also confirmed in the actual test process.
According to the reading of the interferometer in the test process, the measurement result of the linear expansion coefficient in any temperature interval of the cylinder (5) can be obtained by calculation as follows:
calculating the length variation delta L of the quartz tube (21) at different temperature moments through the formula (1)c
ΔLc＝λc·Lc·ΔT (1)
Calculating displacement variation Delta L of the measuring reflector by formula (2)m，
ΔLm＝ΔL+ΔLc(2)
Finally, calculating the linear expansion coefficient lambda of the cylinder (5) to be measured according to the formula (3) and the formula (4)m。
ΔLm＝λm·Lm·ΔT (3)
Wherein: Δ L is the interferometer reading, i.e. the measurement optical path variation minus the reference optical path variation; Δ LmIn order to measure the optical path change of the optical path, the length change of the cylinder (5) to be measured along with the temperature is equal in the test; Δ LcFor the change of the optical path of the reference light path, the length change quantity of the quartz tube (21) along with the temperature is equal in the test; lambda [ alpha ]mIs the linear expansion coefficient, L, of the cylinder (5) to be measuredmIs the length, lambda, of the cylinder (5) to be measuredcIs the linear expansion coefficient of the quartz tube (21), is calibrated before the test, LcThe length of the light path is participated in by the quartz tube (21), and the measurement is carried out on site according to the construction result of the device. Calculating the length variation delta L of the quartz tube (21) at different temperature moments through a formula (3)cCalculating the variation DeltaL of the measuring optical path length by the formula (1)mFinally, the linear expansion coefficient lambda of the cylinder (5) to be measured can be calculated according to the formula (4)m。
The method is successfully applied to the temperature linear expansion coefficient test of a certain type of carbon fiber composite material lens barrel, has higher precision which is superior to 0.1 mu m, basically depends on the frequency stabilization precision of the used laser interferometer, and has the precision improved by more than 10 times compared with the traditional contact measurement method with the mu m-level precision. Meanwhile, another quartz tube with a known linear expansion coefficient is retested by the method, the obtained result is basically equal to the calibrated value, the error is less than 5%, and the accuracy of the measuring method is demonstrated.
The interference device used by the invention only consists of the light splitting component, the reflector component and the standard tube, and each component has smaller volume and weight and is easy to build and adjust. Compared with the traditional length measuring device such as a micrometer, a standard measuring rod, a contourgraph, a coordinate instrument and the like, the length measuring device is lighter and smaller, and has stronger adaptability to the space of a field.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Claims (7)
1. A high-precision barrel linear expansion coefficient measuring device is characterized by comprising a connecting beam splitting prism assembly (1), a quartz tube assembly (2), a connecting reflecting mirror assembly (3) and a V-shaped block assembly (4);
an upper flange and a lower flange are arranged at two ends of the cylinder body (5) to be tested;
the connecting beam splitting prism component (1) and the connecting reflector component (3) are arranged at two ends of an upper flange and a lower flange of the cylinder body (5) to be measured, and after the connecting beam splitting prism component (1) and the connecting reflector component (3) are arranged on the cylinder body (5) to be measured, V-shaped grooves are formed in two opposite surfaces of the connecting beam splitting prism component (1) and the connecting reflector component (3);
two ends of the quartz tube component (2) are respectively arranged in V-shaped grooves in the connecting beam splitting prism component (1) and the connecting reflecting mirror component (3);
a cylinder (5) to be measured is arranged on the V-shaped block assembly (4), the V-shaped block assembly (4) is adjusted to enable the central axis of the cylinder (5) to be horizontal relative to a ground plane, and the relative position relation of the connecting beam splitting prism assembly (1), the quartz tube assembly (2) and the connecting reflector assembly (3) is adjusted to enable an interferometer arranged on the other side of the connecting beam splitting prism assembly (1) to receive the signal which enters the interferometer after being incident from the connecting beam splitting prism assembly (1) and reflected by the connecting reflector assembly (3) to be the maximum;
the device needs to record the length variation of the cylinder (5) to be measured at different temperatures by the interferometer under the condition of temperature control, and finally calculates the linear expansion coefficient of the cylinder (5) to be measured according to the length variation at different temperatures.
2. A high-precision barrel linear expansion coefficient measuring device according to claim 1, wherein: the connecting beam splitting prism component (1) comprises a beam splitting prism component (11), a beam splitting prism connecting piece A (12) and a beam splitting prism connecting piece B (13);
the beam splitting prism component (11) and the beam splitting prism connecting piece A (12) are both connected with a beam splitting prism connecting piece B (13), the beam splitting prism connecting piece B (13) is connected with one end of the cylinder body (5) to be tested through a flange, and a V-shaped groove is formed in the beam splitting prism connecting piece A (12);
the beam splitting prism component (11) comprises a polarization beam splitting component (111), a beam splitting prism mirror chamber (112), a beam splitting prism left cover (113) and a beam splitting prism right cover (114);
the polarization beam splitting component (111) is arranged in the beam splitting prism mirror chamber (112), and the polarization beam splitting component (111) is covered by the beam splitting prism left cover (113) and the beam splitting prism right cover (114) together to play a role in protection;
the polarization light splitting component (111) comprises four prisms, a reflecting mirror 1, a spectroscope 2 and a reflecting mirror 2 are sequentially arranged from top to bottom, the spectroscope 1 and the spectroscope 2 are combined into a square, and the junction of the spectroscope 1 and the spectroscope 2 is a bonding surface of the spectroscope 1 and the spectroscope 2;
laser beams enter from the spectroscope 1, a part of light is transmitted to the connecting reflection mirror assembly (3) through the bonding surface of the spectroscope 1 and the spectroscope 2, is reflected by the connecting reflection mirror assembly (3), enters the spectroscope 2, is reflected to the reflection mirror 2 through the bonding surface of the spectroscope 1 and the spectroscope 2, is reflected by the reflection mirror 2, is transmitted to the reflection mirror 1 through the spectroscope 1 and the spectroscope 2, is reflected to the connecting reflection mirror assembly (3) through the reflection mirror 1, enters the reflection mirror 1 after being reflected by the connecting reflection mirror assembly (3), is reflected by the reflection mirror 1, enters the spectroscope 1, is reflected through the bonding surface of the spectroscope 1 and the spectroscope 2, exits from the spectroscope 1, and emergent light and incident light of the spectroscope 1 are parallel.
3. A high-precision barrel linear expansion coefficient measuring device according to claim 2, wherein: the quartz tube assembly (2) comprises a quartz tube (21), a quartz tube fixing connecting piece (22) and a counterweight (23);
the quartz tube fixing connecting piece (22) is arranged at one end in the quartz tube (21), and the balance weight (23) is connected with the quartz tube fixing connecting piece (22) through a connecting wire;
two ends of a quartz tube (21) are respectively inserted into the V-shaped grooves of the beam splitting prism component (1) and the connecting reflector component (3), and a connecting line of the counterweight (23) passes through the V-shaped groove of the beam splitting prism component (1) and freely hangs beside a cylinder to be measured;
the end face of the quartz tube (21) is tightly attached to the beam splitter prism connecting piece A (12) through the dead weight of the counterweight (23), so that the quartz tube (21) is prevented from rotating after the adjustment of the quartz tube assembly (2) and the connecting reflector assembly (3) is completed.
4. A high-precision barrel linear expansion coefficient measuring device according to claim 3, wherein: the connecting mirror assembly (3) comprises: a reflector connector A (31), a quartz tube connector (32), a reflector connector B (33) and a reflector assembly (34); the connecting reflector component (3) is connected with the other flange end face of the cylinder (5) to be measured through a reflector connecting piece A (31);
a mirror assembly (34) comprising: a reference mirror assembly (341), a measurement mirror assembly (342) and a mirror connection plate (343); the reflector connecting plate (343) is removable, before the reflector connecting plate (343) is removed, the reference reflector assembly (341) and the measurement reflector assembly (342) are connected through the reflector connecting plate (343); the measurement reflector assembly (342) is connected with the reflector connector A (31) through a reflector connector B (33), and after the reflector connecting plate (343) is removed, the reference reflector assembly (341) is connected with the quartz tube (21) through a quartz tube connector (32);
the reference mirror assembly (341) comprises a reference mirror (3411), a reference mirror cap (3412), and a reference mirror chamber (3413);
the measurement reflector assembly (342) comprises a measurement reflector (3421), a measurement reflector cover (3422) and a measurement reflector chamber (3423);
the reference reflector (3411) is arranged in a reference reflector chamber (3413), the measuring reflector (3421) is arranged in a measuring reflector chamber (3423), a reference reflector cover (3412) covers the reference reflector (3411), and a measuring reflector cover (3422) covers the measuring reflector (3421) for protection;
the reflector connector A (31) is provided with a V-shaped groove which can be inserted with a quartz tube (21).
5. A high-precision barrel linear expansion coefficient measuring device according to claim 1, wherein: the V-shaped block assembly (4) comprises a base (41) and a baffle plate (42), the baffle plate (42) is arranged on the base (41),
the V-shaped block assemblies (4) are four in number and two in number, the flanges on two sides of the cylinder body (5) to be tested are respectively supported, and the cylinder wall is not contacted with the V-shaped block assemblies (4); the base (41) plays a role of supporting the flange, and the baffle (42) plays a limiting role of clamping the flange;
and adjusting the distance of the V-shaped block assemblies (4) supporting the flanges at the two sides of the cylinder body (5) to be measured to level the cylinder body.
6. A high-precision barrel linear expansion coefficient measuring device according to claim 1, wherein: the metal structural members in the connecting beam splitting prism component (1) and the connecting reflector component (3) are made of 4J 32.
7. A measuring method of a high-precision cylinder linear expansion coefficient measuring device according to any one of claims 3 to 6, characterized by comprising the following steps:
(1) calibrating and measuring the linear expansion coefficient of the quartz tube (21);
(2) adjusting the V-shaped block assembly (4) to enable the cylinder (5) to be horizontal, adjusting the relative position relation of the connecting beam splitting prism assembly (1), the quartz tube assembly (2) and the connecting reflector assembly (3), and enabling the signal intensity entering the interferometer after the incident light from the connecting beam splitting prism assembly (1) is reflected by the connecting reflector assembly (3) to be maximum;
(3) controlling the temperature of the measuring device and the cylinder (5) to be measured, and recording the readings of the interferometer at different temperature moments;
(4) according to the reading delta L of the interferometer, the linear expansion coefficient lambda of the cylinder (5) to be measured is calculatedmThe method comprises the following steps:
calculating the length variation delta L of the quartz tube (21) at different temperature moments through the formula (1)c
ΔLc＝λc·Lc·ΔT (1)
Calculating displacement variation of the measuring reflector by formula (2)ΔLm，
ΔLm＝ΔL+ΔLc(2)
Finally, calculating the linear expansion coefficient lambda of the cylinder (5) to be measured according to the formula (3) and the formula (4)m；
ΔLm＝λm·Lm·ΔT (3)
Wherein: Δ L is the interferometer reading, i.e. the measured mirror displacement variation subtracts the reference mirror displacement variation; Δ LmIn order to measure the displacement variation of the reflector, the length variation of the cylinder (5) to be measured along with the temperature is equal to the length variation of the cylinder to be measured along with the temperature in the test; Δ LcIn order to refer to the displacement variation of the reflector, the length variation of the quartz tube (21) along with the temperature is equal in the test; lambda [ alpha ]mIs the linear expansion coefficient, L, of the cylinder (5) to be measuredmFor the length of the cylinder (5) to be measured, delta T represents the temperature variation, lambdacIs the linear expansion coefficient of the quartz tube (21), is calibrated before the test, LcThe length of the quartz tube (21) participating in the light path, namely the length between the connecting beam splitting prism component (1) and the connecting reflecting mirror component (3), is measured on site according to the construction result of the device.
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|---|---|---|---|---|
| JP2003166959A (en) * | 2001-12-04 | 2003-06-13 | Sumitomo Bakelite Co Ltd | Measuring method of coefficient of linear expansion, and sample-mounting chuck used for the same |
| CN104198438A (en) * | 2014-09-15 | 2014-12-10 | 清华大学 | Measuring system for expansion coefficient of material |
| CN106017333A (en) * | 2016-07-22 | 2016-10-12 | 浙江理工大学 | Phase modulation based dual-laser single-frequency interference nanometer displacement measurement device and method |
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| DE102015113548A1 (en) * | 2015-07-24 | 2017-01-26 | Schott Ag | High-precision method for determining the thermal expansion |
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|---|---|---|---|---|
| JP2003166959A (en) * | 2001-12-04 | 2003-06-13 | Sumitomo Bakelite Co Ltd | Measuring method of coefficient of linear expansion, and sample-mounting chuck used for the same |
| CN104198438A (en) * | 2014-09-15 | 2014-12-10 | 清华大学 | Measuring system for expansion coefficient of material |
| CN106017333A (en) * | 2016-07-22 | 2016-10-12 | 浙江理工大学 | Phase modulation based dual-laser single-frequency interference nanometer displacement measurement device and method |
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