CN102689300A - Piezoelectric driving micro clamping forceps for precise assembly and method for clamping parts - Google Patents

Abstract

The invention discloses piezoelectric driving micro clamping forceps which are used for precise assembly and provided with a clamping force sensing function, and a method for clamping parts by using the micro clamping forceps. By the piezoelectric driving micro clamping forceps, the motion of the micro clamping forceps can be accurately controlled by controlling the piezoelectricity ceramic driving voltage, so that cross-scale irregularly-shaped parts (0.1mu m to 6mm) are clamped in a lossless mode. In the clamping process, a microscopic visual camera is arranged above the micro clamping forceps, and a proper clamping head is selected according to the sizes of the clamped parts; when the clamping forceps are not contacted with the parts, the head of the clamping forceps is controlled to approach the parts according to a microscopic visual image; and when the clamping forceps are contacted with the parts, clamping force is sensed by a micro force sensor, and the motion of the micro clamping forceps is controlled according to a feedback force signal. By the micro clamping forceps and the method, the accuracy and reliability of the micro clamping forceps can be improved; and the parts can be clamped in the lossless mode, so that the requirement of precise assembly is met.

Description

Be used for the little gripper clamp of Piezoelectric Driving of accurate assembling and the method for clamping part

Technical field

The present invention relates to accurate assembling and field of micro electromechanical technology, be specifically related to a kind of little gripper clamp of Piezoelectric Driving of accurate assembling and method of clamping part of being used for.

Background technology

Development along with Micrometer-Nanometer Processing Technology, microelectric technique, MEMS etc. presses for a plurality of minute yardstick parts is assembled into complication system.Little gripper clamp is as the end effector that directly contacts with the clamping object in little assembly system, and the completion of little fittage is played decisive role.There are following three shortcomings in conventional clamper: the positioning accuracy that 1) can't reach micron level; 2) can not realize striding the parallel clamping of yardstick part; 3) do not possess the perception of chucking power.Therefore, traditional clamper can't be used in the precision assembling.

The little gripper clamp of Piezoelectric Driving possesses advantages such as response is fast, resolution ratio is high, control accuracy is high, chucking power is big, therefore is widely used in various fields.The little gripper clamp of Piezoelectric Driving that research has the chucking power induction is a research focus in the accurate assembling.

Summary of the invention

The object of the present invention is to provide a kind of little gripper clamp of general Piezoelectric Driving with little force sensing function of accurate assembling and method of clamping part of being used for, overcome the deficiency of traditional gripper clamp, realize harmless clamping special-shaped minute yardstick part.

For realizing above-mentioned purpose, according to an aspect of the present invention, a kind of little gripper clamp of Piezoelectric Driving that is used for accurate assembling is proposed; It is characterized in that this little gripper clamp comprises: dismantled and assembled clamping head 1, dismantled and assembled clamping head 18, piezoelectric strain sheet 2, piezoelectric strain sheet 17; Submissive clamping device 3, last fixed cap 6, piezoelectric ceramic actuator 8; Pretension piece 10, top 14 and little gripper clamp base 12;

Dismantled and assembled clamping head 1, dismantled and assembled clamping head 18 are sleeved on the retaining part of submissive clamping device 3; Submissive clamping device 3 is connected with little gripper clamp base 12 with screw 16 through screw 4, screw 5, screw 15; Little gripper clamp base 12 is fixed on the electronic or manual platform, so that little gripper clamp automation or semi-automatic motion; Piezoelectric strain sheet 2, piezoelectric strain sheet 17 stick on the maximum flexible hinge place of submissive clamping device 3 deflections;

Said piezoelectric ceramic actuator 8 profiles are cylinder, and an end inserts the circular hole on little gripper clamp base 12, and the other end contacts with top 14; Last fixed cap 6 is pressed on the piezoelectric ceramic actuator 8, and links to each other with little gripper clamp base 12 with screw 13 through screw 7; Last fixed cap 6 and piezoelectric ceramic actuator 8 contacts site are designed to circular-arc, make piezoelectric ceramic actuator 8 in axial direction promote top 14 motions only; In the semi-circular groove that top 14 is placed on little gripper clamp base 12, an end and submissive clamping device 3 contact, and the other end contacts with piezoelectric ceramic actuator 8;

Pretension piece 10 is connected with little gripper clamp base 12 with screw 11 through screw 9, for piezoelectric ceramic actuator 8 provides pretightning force.

According to a further aspect in the invention, also propose a kind of method of using described little gripper clamp clamping part, it is characterized in that this method may further comprise the steps:

Step 1 will treat that the clamping part is placed on the automatically controlled mobile platform, and select suitable clamping head according to the physical dimension of part to be assembled;

Step 2 is installed the micro-vision camera above little gripper clamp, camera is aimed at the clamping head of little gripper clamp, to gather the position coordinates and the attitude angle at assembly space of part to be assembled;

Step 3, according to said camera collection to position of treating the clamping part and attitude, control and the automatically controlled mobile platform motion that little gripper clamp base is connected make and treat that the clamping part gets into the working range of clamping head;

Step 4 after treating that the clamping part gets into the clamping head working range, is at first confirmed clamping head and is treated the distance between the clamping part through the micro-vision image of gathering; Connect the control power supply of piezoelectric ceramic actuator then, the displacement of piezoelectric ceramic actuator output movement, and with this output displacement pass to submissive clamping device, submissive clamping device is converted into the axial-movement of piezoelectric ceramic actuator the holding action of clamping head; Output displacement through the control piezoelectric ceramic actuator at last makes the clamping head contact treat the clamping part;

Step 5, when clamping head with treat that the clamping part contacts after, as input, the deflection at the flexible hinge place of the detected submissive clamping device of piezoelectric strain sheet is output with the input voltage of piezoelectric ceramic actuator, adopts the PID method to carry out closed-loop control;

Step 6 when chucking power satisfies requiring of clamping part, is cut off the power supply of piezoelectric ceramic actuator, accomplishes the harmless clamping of treating the clamping part.The little gripper clamp of Piezoelectric Driving that the present invention proposes has following advantage: 1) submissive clamping device adopts the configuration mode that lever and parallel four-bar structure combine, and realizes the parallel clamping to the clamping part; 2) contradiction between solution clamping range and the Motion Resolution rate realizes striding clamping resolution ratio higher under the yardstick clamping range; 3) detect clamping deformation through the piezoelectric strain sheet, the size of perception chucking power thus realizes the harmless clamping of part.Said little gripper clamp volume that the present invention proposes is little, in light weight, the limited working space of adaptation fine manipulation microscopically.Compare with other micro clamping device, the present invention has bigger versatility and applicability, has very high practical value.

Description of drawings

Fig. 1 is the vertical view of the little gripper clamp of the present invention.

Fig. 2 is submissive clamping device structure chart.

Fig. 3 is the flexible hinge structure chart.

Fig. 4 is submissive clamping device amplification principle figure.

Fig. 5 is held the sketch map that part is placed on base platform.

Fig. 6 is for using the method flow diagram of little gripper clamp clamping part.

The specific embodiment

For making the object of the invention, technical scheme and advantage clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, to further explain of the present invention.

The present invention can be used for the accurate clamping of part, mobile and assembling.Fig. 1 is the vertical view of the little gripper clamp of the present invention, and as shown in Figure 1, the little gripper clamp of the present invention mainly comprises: dismantled and assembled clamping head 1,18; Piezoelectric strain sheet 2,17, submissive clamping device 3, last fixed cap 6; Piezoelectric ceramic actuator 8, pretension piece 10, top 14 and little gripper clamp base 12.

Dismantled and assembled clamping head 1,18 is sleeved on the retaining part of submissive clamping device 3; Submissive clamping device 3 is connected with little gripper clamp base 12 with 16 through screw 4,5,15; Little gripper clamp base 12 is fixed on the electronic or manual platform, with automation or the semi-automatic motion that realizes little gripper clamp; Piezoelectric strain sheet 2,17 sticks on the maximum flexible hinge place of submissive clamping device 3 deflections; And the maximum strain direction of strain grid sensitive direction and flexible hinge is consistent in the piezoelectric strain sheet, to realize the perception of 2,17 pairs of little gripper clamp chucking powers of piezoelectric strain sheet;

Piezoelectric ceramic actuator 8 can be realized nano level Motion Resolution rate as the drive source of little gripper clamp; Said piezoelectric ceramic actuator 8 profiles are cylinder, and an end inserts the circular hole on little gripper clamp base 12, and the other end contacts with top 14; Use is simultaneously gone up fixed cap 6 and is pressed on the piezoelectric ceramic actuator 8, and links to each other with little gripper clamp base 12 with 13 through screw 7; Last fixed cap 6 and piezoelectric ceramic actuator 8 contacts site are designed to circular-arc, make piezoelectric ceramic actuator 8 in axial direction promote top 14 motions only; In the semi-circular groove that top 14 is placed on little gripper clamp base 12; One end and submissive clamping device 3 contact; The other end contacts with piezoelectric ceramic actuator 8; To come directly towards 14 through pretension piece 10 and be stuck in the middle of submissive clamping device 3 and the piezoelectric ceramic actuator 8, the output displacement and the power output of piezoelectric ceramic actuator 8 passed to submissive clamping device 3;

Pretension piece 10 is connected with little gripper clamp base 12 with 11 through screw 9; For piezoelectric ceramic actuator 8 provides pretightning force; Piezoelectric ceramic actuator 8 closely contacted with submissive clamping device 3 before said pretension piece 10 was used to guarantee the clamping operation on the one hand; Be used to regulate the initial distance (submissive clamping device 3 is converted into the motion between dismantled and assembled clamping head 1 and 18 with the feeding of pretension piece 10, adjusts the distance of little clamping jaw thus) of little clamping jaw on the other hand, to realize the clamping of different scale object;

Submissive clamping device 3 converts piezoelectric ceramic actuator 8 motion in axial direction between dismantled and assembled clamping head 1 and 18 clamping movement.Fig. 2 is the structure chart of submissive clamping device 3, and said submissive clamping device 3 adopts secondary flexible hinge lever and parallel four-bar structure combining.Secondary flexible hinge lever construction amplifies the input secondary of piezoelectric ceramic actuator 8, and wherein one-level is amplified is input as the input displacement y of piezoelectric ceramic actuator 8 along power F direction ₀, be output as the displacement at hinge H2 place; The displacement that is input as hinge H2 place that secondary amplifies is output as the output displacement x of dismantled and assembled clamping head 1 and 18, and is as shown in Figure 2.

H1～H7 is a straight beam type flexible hinge structure, and wherein t is the thickness of flexible hinge thinnest part, and R is the rounding radius, and l is the straight beam partial-length, and b is the thickness of hinge, and is as shown in Figure 3.Parallel four-bar structure on the said submissive clamping device 3 is used to limit secondary flexible hinge lever construction around certain some rotation, realizes the purpose of dismantled and assembled clamping head 1 and 18 parallel clamping part.

The amplification principle of submissive clamping device 3 is as shown in Figure 4, the coordinate (x of the A that sets up an office _A, y _A) be:

$\left\{\begin{array}{c}{x}_A=x_{O^{\&prime;}}+{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\cos {\mathrm{\&theta;}}_1\\ y_A=y_{O^{\&prime;}}+{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_1\sin {\mathrm{\&theta;}}_1\end{array}\right.$

Wherein, (x _{O '}, y _{O '}) be the coordinate of strong point O ', l ₁Be bar l ₁Length, θ ₁Straight line and horizontal angle for AB formation:

Coordinate (the x of point B _B, y _B) be:

$\left\{\begin{array}{c}{x}_B=x_{O^{\&prime;}}-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_2\cos {\mathrm{\&theta;}}_1\\ y_B=y_{O^{\&prime;}}-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_2\sin {\mathrm{\&theta;}}_1\end{array}\right.$

Wherein, l ₂Be bar l ₂Length.

As A end input displacement y upwards ₀The time, bar l ₃Turn clockwise bar l around a B ₂Drive bar l ₃Be rotated counterclockwise around O ', the corner of both direction is all very little and basic identical.Therefore, the coordinate (x of some C _C, y _C) be:

$\left\{\begin{array}{c}{x}_C=x_B\\ y_C=y_B-{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_3\end{array}\right.$

Wherein, l ₃Be bar l ₃Length.

Coordinate (the x of point D _D, y _D) be:

$\left\{\begin{array}{c}{x}_D=x_C-l_4\\ y_D=y_C\end{array}\right.$

Wherein, l ₄Be bar l ₄Length.

Coordinate (the x of point F _F, y _F) be:

$\left\{\begin{array}{c}{x}_F=({\mathrm{<figure-callout\; id="6"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_6+l_7)\cos ({\mathrm{\&theta;}}_2+{\mathrm{\&theta;}}_3)\\ y_F=({\mathrm{<figure-callout\; id="6"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_6+l_7)\sin ({\mathrm{\&theta;}}_2+{\mathrm{\&theta;}}_3)\end{array}\right.$

Wherein, l ₆Be bar l ₆Length, l ₇Be bar l ₇Length,

l ₅Be bar l ₅Length.

Because θ ₁Very little, so cos θ ₁≈ 1, therefore can be imported and export the relation of displacement:

$\mathrm{\&Delta;x}=(l_6+l_7)\cos [\arctan \left(\frac{y_{o^{\&prime;}}-l_3-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HDA00001723277100011.png"\; state="\{\{state\}\}">l</figure-callout>}}_2\frac{{\mathrm{\&Delta;y}}_0}{l_1}}{x_{o^{\&prime;}}-l_2-l_4}\right)+\arctan \frac{l_5}{l_6}],$

According to treating that the clamping accessory size selects rational dismantled and assembled clamping head 1 and 18, the deformation through flexible hinge place on the submissive clamping device 3 of piezoelectric strain sheet 2,17 perception in the clamping process, and gather deformation signal through data acquisition unit.When clamping head 1 with 18 when being held part 19 and contacting, the input voltage according to the deformation signal adjustment piezoelectric ceramic actuator of gathering 8 constitutes closed loop PID control with this, realizes the purpose to the harmless clamping of part.

Fig. 5 is the position view of part to be assembled on the little gripper clamp of the present invention; When precision component is carried out clamping; Being held part 19 is placed on the base platform 20; This base platform is fixed on the vibration-isolating platform, and the electronic or manual platform that fixedly is held little gripper clamp of part 19 also is fixed on the vibration-isolating platform.

The present invention also proposes a kind of method of using said little gripper clamp clamping part simultaneously, and its flow chart is as shown in Figure 6, and this method may further comprise the steps:

Step 1 will treat that the clamping part is placed on the automatically controlled mobile platform, and select suitable clamping head according to the physical dimension of part to be assembled, to realize striding the clamping of yardstick part;

Step 2 is installed the micro-vision camera above little gripper clamp, camera is aimed at the clamping head of little gripper clamp, to gather the position coordinates and the attitude angle at assembly space of part to be assembled;

Step 3, according to said camera collection to the position coordinates of treating the clamping part and attitude angle, control and the automatically controlled mobile platform motion that little gripper clamp base is connected make and treat that the clamping part gets into the working range of clamping head;

Step 4 after treating that the clamping part gets into the clamping head working range, is at first confirmed clamping head and is treated the distance between the clamping part through the micro-vision image of gathering; Connect the control power supply of piezoelectric ceramic actuator then, the displacement of piezoelectric ceramic actuator output movement, and with this output displacement pass to submissive clamping device, submissive clamping device is converted into the axial-movement of piezoelectric ceramic actuator the holding action of clamping head; Output displacement through the control piezoelectric ceramic actuator at last makes the clamping head contact treat the clamping part;

Step 5; When clamping head with treat that the clamping part contacts after; As input, the deflection at the flexible hinge place of the detected submissive clamping device of piezoelectric strain sheet is output with the input voltage of piezoelectric ceramic actuator, adopts the PID method that said deflection is carried out closed-loop control;

The PID closed loop control method is a closed loop control method commonly used in the prior art, does not do at this and gives unnecessary details.

Step 6 when chucking power satisfies requiring of clamping part (deflection at corresponding flexible hinge place arrives certain value), is cut off the power supply of piezoelectric ceramic actuator, accomplishes the harmless clamping of treating the clamping part.

The overall dimensions of little gripper clamp of the present invention is 86mm * 60mm * 5mm (length * wide * height), and the clamping displacement resolution is 20nm, and the clamping repetitive positioning accuracy is 0.15 μ m.The present invention has compact conformation, and characteristics such as working space is big, kinematic accuracy height can realize striding the harmless clamping of yardstick part.

Above-described specific embodiment; The object of the invention, technical scheme and beneficial effect have been carried out further explain, and institute it should be understood that the above is merely specific embodiment of the present invention; Be not limited to the present invention; All within spirit of the present invention and principle, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. the little gripper clamp of Piezoelectric Driving that is used for accurate assembling is characterized in that this little gripper clamp comprises: dismantled and assembled clamping head (1), dismantled and assembled clamping head (18); Piezoelectric strain sheet (2), piezoelectric strain sheet (17); Submissive clamping device (3), last fixed cap (6), piezoelectric ceramic actuator (8); Pretension piece (10), top (14) and little gripper clamp base (12);

Dismantled and assembled clamping head (1), dismantled and assembled clamping head (18) are sleeved on the retaining part of submissive clamping device (3); Submissive clamping device (3) is connected with little gripper clamp base (12) with screw (16) through screw (4), screw (5), screw (15); Little gripper clamp base (12) is fixed on the electronic or manual platform, so that little gripper clamp automation or semi-automatic motion; Piezoelectric strain sheet (2), piezoelectric strain sheet (17) stick on the maximum flexible hinge place of submissive clamping device (3) deflection;

Said piezoelectric ceramic actuator (8) profile is a cylinder, and an end inserts the circular hole on little gripper clamp base (12), and the other end and top (14) contact; Last fixed cap (6) is pressed on the piezoelectric ceramic actuator (8), and links to each other with little gripper clamp base (12) with screw (13) through screw (7); Last fixed cap (6) and piezoelectric ceramic actuator (8) contact site are designed to circular-arc, make piezoelectric ceramic actuator (8) in axial direction promote top (14) motion only; Top (14) is placed in the semi-circular groove on little gripper clamp base (12), and an end and submissive clamping device (3) contact, and the other end contacts with piezoelectric ceramic actuator (8);

Pretension piece (10) is connected with little gripper clamp base (12) with screw (11) through screw (9), for piezoelectric ceramic actuator (8) provides pretightning force.

2. device according to claim 1 is characterized in that, the maximum strain direction of strain grid sensitive direction and flexible hinge is consistent in the said piezoelectric strain sheet, so that little gripper clamp chucking power is carried out perception.

3. device according to claim 2 is characterized in that, said piezoelectric ceramic actuator (8) can be realized nano level Motion Resolution rate as the drive source of little gripper clamp.

4. device according to claim 1; It is characterized in that; Pretension piece (10) will come directly towards (14) and be stuck in the middle of submissive clamping device (3) and the piezoelectric ceramic actuator (8), and the output displacement and the power output of piezoelectric ceramic actuator (8) passed to submissive clamping device (3).

5. device according to claim 1 is characterized in that, piezoelectric ceramic actuator (8) closely contacted with submissive clamping device (3) before said pretension piece (10) was used to guarantee the clamping operation, also was used to regulate the initial distance of little clamping jaw.

6. device according to claim 1 is characterized in that, said submissive clamping device (3) converts piezoelectric ceramic actuator (8) motion in axial direction between dismantled and assembled clamping head (1) and the dismantled and assembled clamping head (18) clamping movement.

7. device according to claim 6 is characterized in that, said submissive clamping device (3) adopts secondary flexible hinge lever and parallel four-bar structure combining, and secondary flexible hinge lever construction amplifies the input secondary of piezoelectric ceramic actuator (8).

8. device according to claim 1; It is characterized in that, when clamping head (1) and clamping head (18) be held part (19) when contacting, according to the input voltage of the deformation signal adjustment piezoelectric ceramic actuator of gathering (8); Part constitutes closed loop PID control, can't harm clamping.

9. method of using the described little gripper clamp clamping part of claim 1 is characterized in that this method may further comprise the steps:

Step 1 will treat that the clamping part is placed on the automatically controlled mobile platform, and select suitable clamping head according to the physical dimension of part to be assembled;

Step 2 is installed the micro-vision camera above little gripper clamp, camera is aimed at the clamping head of little gripper clamp, to gather the position coordinates and the attitude angle at assembly space of part to be assembled;

Step 3, according to said camera collection to the position coordinates of treating the clamping part and attitude angle, control and the automatically controlled mobile platform motion that little gripper clamp base is connected make and treat that the clamping part gets into the working range of clamping head;

Step 4 after treating that the clamping part gets into the clamping head working range, is at first confirmed clamping head and is treated the distance between the clamping part through the micro-vision image of gathering; Connect the control power supply of piezoelectric ceramic actuator then, the displacement of piezoelectric ceramic actuator output movement, and with this output displacement pass to submissive clamping device, submissive clamping device is converted into the axial-movement of piezoelectric ceramic actuator the holding action of clamping head; Output displacement through the control piezoelectric ceramic actuator at last makes the clamping head contact treat the clamping part;

Step 5; When clamping head with treat that the clamping part contacts after; As input, the deflection at the flexible hinge place of the detected submissive clamping device of piezoelectric strain sheet is output with the input voltage of piezoelectric ceramic actuator, adopts the PID method that said deflection is carried out closed-loop control;

Step 6 when chucking power satisfies requiring of clamping part, is cut off the power supply of piezoelectric ceramic actuator, accomplishes the harmless clamping of treating the clamping part.

10. method according to claim 9 is characterized in that, the requirement of said clamping part arrives a certain predetermined value for the deflection at corresponding flexible hinge place.

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