CN108673473B

CN108673473B - Flexible mechanical arm structure

Info

Publication number: CN108673473B
Application number: CN201810601609.2A
Authority: CN
Inventors: 王晓东; 罗怡; 牛文婷; 郇岩强; 任同群; 张志勇
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2018-06-06
Filing date: 2018-06-06
Publication date: 2021-03-26
Anticipated expiration: 2038-06-06
Also published as: CN108673473A

Abstract

The invention relates to a flexible mechanical arm structure, and belongs to the technical field of precision assembly. The flexible mechanical arm structure comprises a flexible unit, a clamp unit and a force sensor unit; the flexible unit plays a role in buffering and protecting during operation through two groups of parallel spring piece force transmission structures, and ensures that the force sensor generates vertical parallel micro-displacement when stressed; the clamp unit is mainly used for picking up, carrying and assembling tiny parts with different shapes and sizes; the force sensor unit is used for providing feedback information of the contact force when the mechanical arm operates. The mechanical arm provided by the invention is provided with the flexible unit, can buffer the reaction force applied to the mechanical arm during operation, and has higher rigidity in both an operation state and a non-operation state, so that the precision of the end effector is improved.

Description

Flexible mechanical arm structure

Technical Field

The invention belongs to the technical field of precision assembly, and particularly relates to a flexible mechanical arm structure.

Background

With the continuous development of high-precision processing technology, the miniaturization and diversification of tiny devices are also tending to. The requirements on the assembling precision and quality of the tiny parts are higher and higher in the precision assembling process, wherein the precision of the end effector is greatly influenced by the structure of the mechanical arm.

Patent application No. CN106671134A discloses a robot arm structure capable of adjusting contact force and reducing deformation, which comprises a body, a tool unit and a plunger unit. The body is used for connecting the tool unit and the plunger unit with a guide rail or a platform of the assembly system; the tool unit realizes the fixation of the end effector, the plunger unit controls the action range of the end effector, a part of counterforce can be counteracted by applying downward force to the spring piece, the deformation is reduced, and the magnitude of the contact force can be controlled by adjusting the rotation amount of the screw plug. The invention can reduce the deformation of the mechanical arm after being stressed and the change of the deformation axis angle of the end effector when the mechanical arm works, but the rigidity is lower when the mechanical arm does not work.

Patent application No. CN201520832943.0 discloses a flexible clamp, which comprises a feeding mechanism, a limiting mechanism and an actuating mechanism. The cylindrical gear drives the annular rack to move left and right, so that left and right feeding movement of the clamp is realized, the limiting mechanism limits the clamp to move only along a straight line, the execution mechanism clamps and releases a workpiece of the clamp, the execution mechanism adopts an integrated design, power is applied by using a piezoelectric ceramic driver, and movement is transmitted by using deformation of the flexible hinge. Although the invention has high flexibility, the rigidity of the clamp is low.

Disclosure of Invention

Aiming at the problems in the prior art, the invention designs and invents a flexible mechanical arm structure, and the mechanical arm with a flexible unit has higher rigidity in both an operating state and a non-operating state, thereby improving the precision of an end effector.

The technical scheme of the invention is as follows:

a flexible robot arm structure includes a flexible unit, a clamp unit, and a force sensor unit;

the clamp unit comprises a mechanical clamp and an adsorption clamp; the mechanical clamp comprises a mechanical clamp cylinder, a mechanical clamp gas claw and an L-shaped clamp finger; the side surface of a mechanical clamp cylinder is fixedly connected with a clamp connecting plate, the lower end of the mechanical clamp cylinder is connected with two mechanical clamp gas claws, an L-shaped clamp finger is connected to the mechanical clamp gas claws, and the connection and disconnection of a gas path of the mechanical clamp cylinder control the opening and closing of the mechanical clamp gas claws, so that the clamping and the release of parts are realized; the adsorption type clamp comprises a needle head fixing plate, a needle head mounting shaft, an air passage and a swing piece picking adsorption block; one end of the needle head fixing plate is fixedly connected with the clamp connecting plate, the other end of the needle head fixing plate is hollowed to form an annular wall, air passages and swing piece picking and adsorbing blocks are uniformly arranged on the annular wall, a jackscrew in each air passage fixes a needle head mounting shaft, a needle head is arranged in the needle head mounting shaft, and the needle head is bent by 90 degrees and used for ventilating and picking small parts; the swing piece picking and adsorbing block is in a convex structure, and is provided with air passages for ventilating and adsorbing large-size parts;

the flexible unit comprises an upper spring piece, a lower spring piece and a spring piece fixing block; one end of the upper spring piece or the lower spring piece is fixed on the spring piece fixing block, and the other end of the upper spring piece or the lower spring piece is correspondingly fixed on the force sensor upper fixing plate or the force sensor lower fixing plate to form an upper group of parallel spring piece force transmission structures and a lower group of parallel spring piece force transmission structures; the spring piece fixing block is fixed on the mechanical arm clamp mounting bottom plate;

one end of the force sensor unit is connected with the clamp unit through a clamp connecting plate, and the other end of the force sensor unit is connected with the flexible unit through an upper fixing plate and a lower fixing plate of the force sensor; the force sensor unit comprises a force sensor, a force sensor upper fixing plate, a force sensor lower stop beam, a mechanical arm upper side baffle, a mechanical arm left side baffle, a mechanical arm right side baffle and an elastic plunger; the upper end of the force sensor is fixed with an upper force sensor fixing plate, the lower end of the force sensor is fixed with a lower force sensor fixing plate, and the lower part of the lower force sensor fixing plate is connected with a lower force sensor stop beam; the left side and the right side of a lower beam of the force sensor are respectively connected with a left baffle plate of the mechanical arm and a right baffle plate of the mechanical arm, the upper ends of the left baffle plate of the mechanical arm and the right baffle plate of the mechanical arm are connected with an upper baffle plate of the mechanical arm, and the upper baffle plate of the mechanical arm, the left baffle plate of the mechanical arm and the right baffle plate of the mechanical arm are all fixedly connected with a clamp mounting base plate of the; the elastic plunger is inserted into a plunger hole of the baffle plate on the upper side of the mechanical arm, and a gap is reserved between the elastic plunger and the force sensor; the elastic plunger and the lower stop beam of the force sensor play a role in protecting the force sensor, the elastic plunger is used for limiting the upward bending deformation of the force sensor after the force sensor receives a reaction force, and the lower stop beam of the force sensor is used for limiting the downward bending deformation of the force sensor under the self gravity.

The invention has the beneficial effects that: under the natural state of the mechanical arm, the lower stop beam pair of the force sensor limits downward bending deformation of the mechanical arm under the self gravity. The mechanical arm plays a role in protecting the elastic plunger when being loaded. Besides the rigidity of the machine is improved, the mechanical arm is provided with a flexible unit, and the buffer protection effect is achieved when the mechanical arm is stressed.

Drawings

Fig. 1 is a schematic structural diagram of a flexible mechanical arm.

Fig. 2 is a schematic structural view of the clamp unit.

Fig. 3 is a schematic diagram of a flexible unit structure.

In the figure: 1, an upper side baffle of the mechanical arm; 2, a baffle plate at the left side of the mechanical arm; 3 an elastic plunger; 4, mechanical type clamp; 5, adsorption type clamp; 6, a first gas path; 7, a first needle; 8, a second needle head; 9, a needle head III; 10, needle head four; 11 needle mounting shaft; 12, swinging a pick-up adsorption block; 13 needle fixing plate; 14 clamping the connecting plate; 15 a force sensor; 16 a mechanical arm right baffle; 17, mounting a bottom plate of a mechanical arm clamp; 18 a mechanical clamp cylinder; 19 mechanical clamp gas claw I; a first 20L-shaped clamping finger; 21, a second air passage; 22, a third gas path; 23, a gas path IV; 24, a gas path five; a 25L-shaped clamping finger II; 26 a mechanical type clamp gas claw II; 27 a first square spacer; 28 spring leaf fixing blocks; 29 an upper spring plate; a fixing plate is arranged on the 30-force sensor; 31, a first square nut; a 32-force sensor lower fixing plate; 33, a second square nut; 34, a lower bumper beam of the force sensor; 35 lower spring leaf; 36 square spacers II.

Detailed Description

The following describes the embodiments of the present invention in detail with reference to the technical solutions and the accompanying drawings by taking the operation components as examples.

the clamp unit comprises an adsorption clamp 5 and a mechanical clamp 4; the mechanical clamp 4 comprises a mechanical clamp cylinder 18, a mechanical clamp gas claw I19, a mechanical clamp gas claw II 26, an L-shaped clamp finger I20 and an L-shaped clamp finger II 25. The adsorption type clamp comprises an adsorption type clamp 5, an air passage I6, a needle I7, a needle II 8, a needle III 9, a needle IV 10, a needle mounting shaft 11, a swing sheet picking adsorption block 12, a needle fixing plate 13, an air passage II 21, an air passage III 22, an air passage IV 23 and an air passage V24. The mechanical clamp 4 is connected with the clamp connecting plate 14 through bolts. The mechanical air claw I19 and the mechanical clamp air claw II 26 are respectively connected to two sides of the mechanical clamp air cylinder 18. The first L-shaped clamping finger 20 is connected to the first mechanical clamp air claw 19 through a bolt, and the second L-shaped clamping finger 25 is connected to the second mechanical clamp air claw 26 through a bolt. The opening and closing of the mechanical clamp gas claw I19 and the mechanical clamp gas claw II 26 are controlled through the connection and disconnection of the gas circuit of the mechanical clamp cylinder 18, so that the clamping and the release of the part are realized. The needle fixing plate 13 is fixedly connected with the clamp connecting plate 14 through bolts. The swing piece picking and adsorbing block 12 is in a convex structure and is connected to the rear end of the needle fixing plate 13 through a stud, and an air passage I6 for ventilating and adsorbing parts is distributed on the swing piece picking and adsorbing block and is suitable for parts with slightly larger sizes. The needle head I7, the needle head II 8, the needle head III 9 and the needle head IV 10 are connected to a needle head mounting shaft 11 which is hollow and provided with internal thread lines through threads, the needle head mounting shaft 11 is fixedly fixed in an air passage II 21, an air passage III 22, an air passage IV 23 and an air passage V24 on a needle head fixing plate 13 through jackscrews, the four needle heads are distributed in a circumferential mode, and the needle heads are bent by 90 degrees and used for picking up small circular or arc-shaped parts.

The flexible unit comprises an upper spring leaf 29, a lower spring leaf 35, a first square nut 31, a second square nut 33, a first square gasket 27, a second square gasket 36 and a spring leaf fixing block 28. The spring leaf fixing block 28 is fixedly connected with the mechanical arm clamp mounting bottom plate 17 through bolts. The front end of the upper spring leaf 29 is fixedly connected with the first square gasket 27 and the spring leaf fixing block 28 through bolts. The rear end of the upper spring leaf 29 is fixedly connected with an upper force sensor fixing plate 30 through a bolt and a square nut 31. The front end of the lower spring piece 35 is fixedly connected with the second square gasket 36 and the spring piece fixing block 28 through bolts. The rear end of the lower spring piece 35 is fixedly connected with the second square nut 33 and the lower force sensor fixing plate 32 through bolts. The lower force sensor fixing plate 32 is fixed to the lower force sensor bumper 34 by bolts. The parts of the whole unit are connected through bolts to form two groups of parallel spring piece force transmission structures, so that the force transmission structures play a role in buffering and protecting during operation, and the parallel spring piece structures can generate vertical parallel micro-displacement when the force sensor is stressed.

The force sensor unit comprises a force sensor 15, a mechanical arm clamp mounting base plate 17, a force sensor upper fixing plate 30, a force sensor lower fixing plate 32, a force sensor lower bumper beam 34, a mechanical arm upper side bumper plate 1, a mechanical arm left side bumper plate 2, a mechanical arm right side bumper plate 16 and an elastic plunger 3. The lower baffle beam 34 of the force sensor is connected with the left baffle plate 2 of the mechanical arm and the right baffle plate 16 of the mechanical arm through bolts, and the left baffle plate 2 of the mechanical arm and the right baffle plate 16 of the mechanical arm are connected with the upper baffle plate 1 of the mechanical arm through bolts. The baffle plate 1 at the upper side of the mechanical arm is fixedly connected with a clamp mounting bottom plate 17 of the mechanical arm through bolts. The force sensor 15 is connected to the force sensor upper fixing plate 30 and the force sensor lower fixing plate 32 by bolts. The elastic plunger is inserted into a plunger hole of a baffle plate on the upper side of the mechanical arm, and a part of gap is reserved between the elastic plunger and the force sensor. When the force sensor 15 is bent upwards under the action of the reaction force, the elastic plunger 3 can limit the upward bending deformation of the force sensor 15, so that the protection effect is achieved; the force sensor lower bumper beam 34 restricts the force sensor 15 from bending and deforming downward under its own weight.

The first step is as follows: the picking-up of coil parts is firstly completed, the downward bending deformation of the mechanical arm under the influence of self gravity is reduced due to the limitation of the lower retaining beam 34 of the force sensor when the mechanical arm is in a non-operation state, the mechanical arm moves to the position above the coil placing position of the feeding platform under the assistance of an industrial camera, the adsorption type clamp 5 is contacted with the coil under the feedback of the force sensor, the force sensor 15 in contact can receive an upward reaction force, the upper spring piece 29 and the lower spring piece 35 can be bent and deformed upwards under the reaction force, the buffer effect is realized on the mechanical arm, and the elastic plunger 3 can apply a downward force to the upper fixing plate 30 of the force sensor to offset a part of the reaction force to reduce the deformation. And controlling the electromagnetic valves of the air passage two 21, the air passage three 22, the air passage four 23 and the air passage five 24 to be opened, completing the pickup of the coil by the needle head I7, the needle head II 8, the needle head III 9 and the needle head IV 10 of the adsorption type clamp under the action of vacuum adsorption force, moving the operation mechanical arm to a position to be assembled of the assembly fixture platform workpiece, closing the electromagnetic valves for supplying power to the air passage two 21, the air passage three 22, the air passage four 23 and the air passage five 24, and completing the assembly task of the coil.

The second step is that: the picking of the two cushion blocks is completed, the mechanical arm is in a non-operation state, downward bending deformation of the mechanical arm under the influence of self gravity is reduced due to the limitation of the lower retaining beam 34 of the force sensor, the operation mechanical arm moves to the position above the placement position of the gasket A of the feeding platform under the assistance of the industrial camera, the adsorption type clamp 5 is in contact with the gasket A under the action of the force sensor, the force sensor 15 in contact can receive an upward reaction force, the upper spring piece 29 and the lower spring piece 35 can be bent and deformed upwards under the reaction force, the mechanical arm is buffered, the elastic plunger 3 applies downward force to the upper fixing plate 30 of the force sensor to offset a part of the reaction force to reduce deformation, the electromagnetic valves of the control air passage three 22 and the air passage four 23 are opened, and the adsorption type clamp needle head two 8 and the needle head three 9 can complete the picking of the gasket A under the. And moving the operation mechanical arm to a position to be assembled of the assembly fixture platform workpiece, closing the electromagnetic valves powered by the third air passage 22 and the fourth air passage 23, and completing the assembly task of the gasket. Then the operation mechanical arm moves to the feeding platform to realize the operation of the gasket, the operation mechanical arm moves to the position above the position where the gasket of the feeding platform is placed with the assistance of the industrial camera, the adsorption type clamp 5 is enabled to be in contact with the gasket under the action of the force sensor, the force sensor 15 can receive an upward reaction force in the contact, the upper spring piece 29 and the lower spring piece 35 can be bent upwards and deformed under the reaction force, the buffer effect is achieved on the mechanical arm, the elastic plunger 3 applies a downward force to the upper fixing plate 30 of the force sensor to offset a part of the reaction force to reduce the deformation, the electromagnetic valves of the air passage two 21 and the air passage five 24 are controlled to be opened, and the first 7 and the fourth 10 needle heads of the adsorption type clamp can complete the picking up of the gasket B under the action of. And moving the operation mechanical arm to a position to be assembled of the assembly fixture platform workpiece, closing the electromagnetic valves for supplying power to the second air passage 21 and the fifth air passage 24, and completing the assembly task of the gasket B.

The third step: the picking of the swing piece is completed, the mechanical arm reduces downward bending deformation of the mechanical arm under the influence of self gravity due to the limitation of the lower retaining beam 34 of the force sensor in a non-operation state, the operation mechanical arm moves to the position above the swing piece placing position of the feeding platform under the assistance of an industrial camera, the swing piece picking and adsorbing block 12 is in contact with the swing piece under the action of the force sensor, the force sensor 15 can receive an upward reaction force in the contact, the upper spring piece 29 and the lower spring piece 35 can bend and deform upwards under the reaction force, the mechanical arm is buffered, the elastic plunger 3 applies downward force to the upper fixing plate 30 of the force sensor to offset part of the reaction force to reduce deformation, the electromagnetic valve of a control gas circuit is opened, and the adsorption hole of the swing piece picking and adsorbing block can complete the picking of the swing piece under the action of vacuum adsorption force. And moving the operation mechanical arm to a position to be assembled of the assembly fixture platform workpiece, closing the electromagnetic valve powered by the gas circuit, and completing the assembly task of the swinging piece.

The fourth step: the picking of the pressing frame is completed, the mechanical arm is prevented from bending and deforming downwards under the influence of self gravity due to the limitation of the lower stop beam 34 of the force sensor in a non-operation state, the operation mechanical arm is moved to the feeding platform, the mechanical clamp is moved to the position of picking the pressing piece under the assistance of the industrial camera, and then the first L-shaped clamping finger 20 and the second L-shaped clamping finger 25 are closed through controlling the action of the air cylinder to complete the clamping of the pressing piece. And moving the operation mechanical arm to a to-be-assembled position of the assembly fixture platform workpiece, closing the cylinder to enable the first L-shaped clamping finger 20 and the second L-shaped clamping finger 25 to be opened so as to be separated from the pressing piece to realize release, and completing the assembly task of the pressing piece.

Claims

1. A flexible mechanical arm structure is characterized by comprising a flexible unit, a clamp unit and a force sensor unit;