CN102840820A - Fine adjustment device for capacitive sensor - Google Patents

Abstract

The invention discloses a fine adjustment device for a capacitive sensor. A fixed sleeve, a spring A, a check ring, a spring B, a one-way thrust ball bearing and a fine adjustment sleeve are sleeved on a capacitive probe from front to back in sequence; the check ring is fixedly connected with the capacitive probe; the fixed sleeve and the fine adjustment sleeve are in slidable nesting with the capacitive probe; the fixed sleeve is in threaded connection with the fine adjustment sleeve; one side of the one-way thrust ball bearing is in contact with the spring B, and the other side of the one-way thrust ball bearing is in contact with the bottom surface of the fine adjustment sleeve; and the rigidity of the spring B is less than the rigidity of the spring A. According to the fine adjustment device, smaller fine adjustment can be realized by using a double-spring fine adjustment structure, and no reverse clearance is formed, so that the fine adjustment for the distance between a probe of the capacitive sensor and a tested workpiece is smaller; and the fine adjustment device is more convenient to adjust.

Description

The micromatic setting of capacitance type sensor

Technical field

The invention belongs to the mechanical measurement technique field, relate to a kind of micromatic setting of capacitance type sensor.

Background technology

Capacitive transducer is made up of two pole plates, can measure the variation of micro-displacement.In the measuring process usually the measurand of metal as a pole plate, capacitance probe is as the another one pole plate.Capacitive transducer is mixed and is measured stand and can carry out various precision measurements, like the thickness of workpiece, internal diameter, external diameter, ovality, the depth of parallelism, linearity, diameter run-out etc., is widely used in length and displacement measurement in the machinery manufacturing industry.

Capacitive transducer need be finely tuned the distance between pole plate when measuring; Existing differential thread micromatic setting, because the pitch restriction, degree of regulation is not high; And there is backlass in screw thread in the adjustment process; For differential thread, adjustment amount is more little, and the accuracy of adjustment amount receives the influence of pitch precision more easily.

Summary of the invention

The micromatic setting that the purpose of this invention is to provide a kind of capacitance type sensor has solved existing differential thread micromatic setting, because pitch restriction, degree of regulation is not high, and there is the problem of backlass in screw thread in the adjustment process.

The technical scheme that the present invention adopted is that a kind of micromatic setting of capacitance type sensor on capacitance probe, is set with fixed muffle, spring A, back-up ring, spring B, single direction thrust ball bearing, fine setting sleeve from front to back successively; Back-up ring is fixedly connected with capacitance probe, and the socket of sliding between fixed muffle and fine setting sleeve and the capacitance probe is adopted thread connection between fixed muffle and the fine setting sleeve; One side of single direction thrust ball bearing contacts with spring B, and the opposite side of single direction thrust ball bearing contacts with the bottom surface of fine setting sleeve.

The invention has the beneficial effects as follows, adopt the dual spring fine tuning structure, can realize littler amount trimmed, and not have backlass, make the amount trimmed of distance between probe and the measured workpiece of capacitive transducer littler, adjust more convenient.With the fine tuning structure of the fixing differential thread of sensitivity relatively, can adapt to the demand of sensor different sensitivity better.Apparatus of the present invention are owing to finely tune quill to direct feeler, and pitch error is not reacted directly in the sensor displacement, on the contrary, can also reduce the influence of pitch error to the sensor displacement through two springs.

Description of drawings

Fig. 1 is the structural representation of the micromatic setting of capacitance type sensor of the present invention.

Among the figure, 1. fixed muffle, 2. spring A, 3. back-up ring, 4. spring B, 5. single direction thrust ball bearing, 6. fine setting sleeve, 7. capacitance probe, 8. holding screw.

Embodiment

With reference to Fig. 1; The micromatic setting structure of capacitance type sensor of the present invention is; On capacitance probe 7; Be set with fixed muffle 1, spring A2, back-up ring 3, spring B 4, single direction thrust ball bearing 5, fine setting sleeve 6 from front to back successively, the rigidity (elasticity) of spring B 4 wherein is less than the rigidity (elasticity) of spring A2; Back-up ring 3 is fixedly connected with capacitance probe 7 through holding screw 8, and the socket of sliding between fixed muffle 1 and fine setting sleeve 6 and the capacitance probe 7 is adopted thread connection between fixed muffle 1 and the fine setting sleeve 6; One side of single direction thrust ball bearing 5 contacts with spring B 4, and the opposite side of single direction thrust ball bearing 5 contacts with the bottom surface of fine setting sleeve 6.

The capacitance probe 7 of sensor connects with two springs simultaneously, and two spring series connection are provided with, and constitute spring-probe-spring structure; Through rotating fine setting sleeve 6, change the decrement of two springs; The amount trimmed of sensor capacitance probe 7 is under fine setting sleeve 6 corner the same terms, and is only relevant with the ratio of rigidity of two springs.

When fine setting sleeve 6 turned over 1rad, the displacement of capacitance probe 7 was called the sensitivity of micromatic setting.The ratio of rigidity of two springs is depended in the sensitivity of device, through changing the ratio of rigidity of two springs, can change the sensitivity of micromatic setting.

Apparatus of the present invention adopt the socket of connect with the capacitance probe 7 of capacitive transducer of the spring of two different-stiffness, through finely tuning pop one's head in 7 the displacement of sleeve 6 control capacittances.Because the rigidity of the spring B 4 of the ratio of rigidity rear end of the spring A2 of front end is big, the axial internal clearance that 6 rotations of fine setting sleeve produce is bigger than capacitance probe 7 amount of movements, thereby realizes (forward) fine setting of capacitive transducer.Because fine setting sleeve 6 bears the acting force of two springs always, there is not backlass during the displacement of reverse adjusting fine setting sleeve 6.

The first, the principle of work of the micromatic setting of capacitance type sensor of the present invention is:

Micromatic setting of the present invention in use, fixed muffle is fixed, regulates the fine setting sleeve and turns over an angle, corresponding axial displacement is Δ, the deflection of spring A is a Δ _y, the deflection of spring B is a Δ _r, because two spring series connection have following relation: Δ _y+ Δ _r=Δ, the equivalent spring rigidity of two serial springs is:

K wherein _yBe the rigidity of spring A, k _rRigidity for spring B.

The suffered power of each spring equates with the stressed of equivalent spring, for

Promptly Because k _r＜k _y+ k _r, Δ must be arranged _y＜Δ, the deflection of spring A, promptly the amount trimmed of sensor probe is less than the axial displacement of fine setting sleeve.Under axial displacement the same terms of fine setting sleeve, the amount trimmed of probe depends on that the ratio of rigidity of two springs is: ${\mathrm{\Δ}}_y=\frac{k_r}{k_y+k_r}\mathrm{\Δ}=\frac{1}{k_y/k_r+1}\mathrm{\Δ}---\left(1\right)$

If the radian that θ turns over for the fine setting sleeve; P is the pitch of bush whorl, and relation is between the axial displacement of sleeve and the corner:

Then formula (1) is transformed to: ${\mathrm{\&Delta;}}_y=\left(\frac{1}{k_y/k_r+1}\right)\left(\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA00002069529100011.png"\; state="\{\{state\}\}">P</figure-callout>}}{2\mathrm{\&pi;}}\right)\mathrm{\&theta;}---\left(2\right)$

Change the ratio of rigidity of two springs, under the identical condition of corner, can obtain different probe amount trimmed Δs _yCompare with the nonadjustable differential thread of amount trimmed, have adaptability preferably.Through changing the spring rate relation, can satisfy the fine setting needs of the sensor of different sensitivity.The displacement of popping one's head in when the sensitivity of micromatic setting turns over 1rad for the fine setting sleeve is represented with ρ.

In addition, can be known by Fig. 1 because the effect that the fine setting sleeve bears the spring extrapolability always, no matter the fine setting sleeve is just changeing still counter-rotating, thread pitch can not influence the displacement of capacitance probe 7.

The second, the fine setting sleeve pitch error in apparatus of the present invention is to the impact analysis of sensor displacement:

Suppose that the fine setting sleeve turns over 1rad, because the quill that pitch error is brought is δ to displacement error, the sensor displacement error that causes then is δ _y, the deflection of spring B is δ _r, then relation is δ between the three _y+ δ _r=δ, owing to have series relationship between two springs, the equivalent stiffness of two springs does

Each spring stress of series connection equates then have with the stressed of equivalent spring

Promptly

Because k _r＜k _y+ k _r, δ must be arranged _y＜δ, the sensor displacement error is less than the pitch error of fine setting sleeve.Work as k _rk _yThe time, think that promptly the pitch error of fine setting sleeve does not influence the sensor displacement, this is the not available advantage of micromatic setting of differential thread.

Embodiment

Make a micromatic setting, require the capacitance probe 7 long H=84mm of sensor, diameter 9mm, the fine setting sensitivity of expectation is 1 μ m/rad.

Step 1 is confirmed the spring rate ratio.Get the pitch P=2mm of screw thread on the fine setting sleeve, known fine setting sensitivity ρ=10 ^-3Mm/rad, substitution formula (2): $\frac{k_y}{k_r}\&ap;318---\left(3\right)$

Step 2 is confirmed the parameter of spring.According to existing disclosed technical literature data, (annotate, refer to by Yang Kezhen " Fundamentals of Machine Design " [M] that Cheng Guangyun, Li Zhongsheng edit and publish jointly at this. Beijing. Higher Education Publishing House, 2006, p308 ~ 318 records), the rigidity of each spring is:

$\left\{\begin{array}{c}{k}_y=\frac{\mathrm{<figure-callout\; id="4"\; label="G\; d\; y"\; filenames="HDA00002069529100011.png"\; state="\{\{state\}\}">G</figure-callout>}{d}_y^{}{}_4^{}}{8{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00002069529100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_2^3{n}_y}\\ k_r=\frac{\mathrm{<figure-callout\; id="4"\; label="G\; d\; r"\; filenames="HDA00002069529100011.png"\; state="\{\{state\}\}">G</figure-callout>}{d}_r^{}{}_4^{}}{8{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00002069529100011.png"\; state="\{\{state\}\}">D</figure-callout>}}_2^3{n}_r}\end{array}\right.---\left(4\right)$

Wherein G is a shear modulus, d _yAnd d _rBe respectively the steel wire diameter of spring A and spring B, D ₂Be mean diameter of coil (two springs are got identical middle footpath), n _yAnd n _rBe respectively the number of turns of spring A and spring B.

The value substitution formula (3) of formula (4) is got: $\frac{d_y^4{n}_r}{d_r^4{n}_y}=318,---\left(5\right)$

Suppose to get d _y=4mm, d _r=1mm, n _y=7, n _r=9, according to above-mentioned open source literature, spring free height (promptly not the height of spring during stand under load) does $\left\{\begin{array}{c}{H}_{0y}=n_y{\mathrm{\&delta;}}_y+(n_{y1}-0.5)d_y\\ H_{0r}=n_r{\mathrm{\&delta;}}_r+(n_{r1}-0.5)d_r\end{array}\right.,---\left(6\right)$ δ _yAnd δ _rBe respectively spring A spacing and spring B spacing, n _Y1And n _R1Be respectively the spring number of total coils, with aforementioned number of coils n _yAnd n _rFollowing relation is arranged: $\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="n\; y"\; filenames="HDA00002069529100011.png"\; state="\{\{state\}\}">n</figure-callout>}}_y=n_y+(1.5~2.5)\\ {\mathrm{<figure-callout\; id="1"\; label="n\; r"\; filenames="HDA00002069529100011.png"\; state="\{\{state\}\}">n</figure-callout>}}_r=n_r+(1.5~2.5)\end{array}\right.,$ The spacing of getting spring A and spring B all is 1mm, gets according to formula (6): $\left\{\begin{array}{c}{H}_{0y}=39\mathrm{Mm}\\ H_{0r}=19\mathrm{Mm}\end{array}\right..---\left(7\right)$

Step 3, the length of check spring.If the back-up ring thickness between two springs is got 10mm, fixed muffle is 3mm with the end surface thickness of fine setting sleeve,

H then _Oy+ H _Or+ 10+3+3=74mm＜84mm, the length that shows micromatic setting meets design requirement less than sensor probe length.

Claims (3)

1. the micromatic setting of a capacitance type sensor; It is characterized in that: on capacitance probe (7), be set with fixed muffle (1), spring A (2), back-up ring (3), spring B (4), single direction thrust ball bearing (5), fine setting sleeve (6) from front to back successively; Back-up ring (3) is fixedly connected with capacitance probe (7), and the socket of sliding between fixed muffle (1) and fine setting sleeve (6) and the capacitance probe (7) is adopted thread connection between fixed muffle (1) and the fine setting sleeve (6); One side of single direction thrust ball bearing (5) contacts with spring B (4), and the opposite side of single direction thrust ball bearing (5) contacts with the bottom surface of fine setting sleeve (6).

2. the micromatic setting of capacitance type sensor according to claim 1, it is characterized in that: the rigidity of described spring B (4) is less than the rigidity of spring A (2).

3. the micromatic setting of capacitance type sensor according to claim 1, it is characterized in that: described back-up ring (3) is fixedly connected through holding screw (8) with capacitance probe (7).

Images