CN102615642B - Parallel manipulator capable of realizing five-coordinate machining capacity - Google Patents

Abstract

The invention discloses a parallel manipulator capable of realizing five-coordinate processing, which includes a fixed frame, the center of the fixed frame base is connected with a driven branch chain through a moving pair, and uniformly distributed brackets are arranged around the driven branch chain. First, second and third kinematic chains, the first, second and third kinematic chains are fixed on the fixed frame, a moving platform is arranged below the fixed frame, and the moving platform includes the first The first platform and the second platform are two parts; the first platform and the second platform are rotatably connected by bearings; the lower end of the driven branch chain and the first platform pass through a third hinge with two rotational degrees of freedom Connection; the lower end of the first kinematic chain is rotationally connected with the first platform through a fourth hinge with three rotational degrees of freedom, and the second and third kinematic chains are connected to the first platform with the same connection structure. The invention has good fast-forward ability and dynamic performance, high overall rigidity, fast speed, high positioning accuracy and repeat positioning accuracy.

Description

Parallel manipulator capable of five-coordinate machining

technical field

The invention relates to a robot, in particular to a parallel robot capable of realizing five-coordinate processing. the

Background technique

According to patents US4732525 and ZL200510015095.5, it is known that the existing multi-coordinate manipulators are generally implemented in the form of a hybrid structure with a few degrees of freedom parallel mechanism supplemented by a positioning head. The multi-coordinate processing capability includes the position positioning of the moving platform and the attitude positioning of the end effector. Among them, the position positioning of the moving platform of the mechanism is realized by a parallel mechanism with few degrees of freedom, which is mainly performed by adjusting the servo motor installed on the active branch chain; the attitude positioning of the end effector is realized by the positioning head (such as A/C double swing head), It is performed by adjusting a servo motor mounted on a double oscillating head. the

The shortcomings of this type of manipulator are: the positioning head is equipped with a servo motor and a reducer, etc., and the weight is too large, which affects the response ability and dynamic performance of the mechanism. The rigidity and mass of the mechanism are relatively small, and the overall rigidity is difficult to guarantee. the

Contents of the invention

In order to solve the technical problems existing in the known technology, the present invention provides a parallel manipulator capable of five-coordinate processing. The power head has good fast-forward capability and dynamic performance, high overall rigidity, fast speed, positioning accuracy and repeat positioning accuracy. high. the

The technical solution adopted by the present invention to solve the technical problems existing in the known technology is: a parallel manipulator capable of realizing five-coordinate processing, characterized in that it includes a fixed frame, and the center of the fixed frame base passes through the moving pair and the slave The moving branch chain is connected, and the first, second and third kinematic chains are evenly distributed around the driven branch chain, and the first, second and third kinematic chains are fixed on the fixed frame, The first kinematic chain includes the first active branch chain, the second kinematic chain includes the second and the third active branch chain, the third kinematic chain includes the fourth and the fifth active branch chain, and the first, second, and first Three, the structure of the fourth and fifth active branches is the same;

Each of the active branch chains includes a wall plate fixedly connected to the fixed frame, and a servo motor is installed on the top of the wall plate, and the servo motor drives a first ball screw connected to the first ball screw. The first nut, the first nut is fixed in the connection block, the connection block is slidably connected to the guide rail, the guide rail is fixed on the wall plate, and the connection block passes through the second rotation degree of freedom. The two hinges are connected to the upper end of the driven rod; a moving platform is arranged below the fixed frame, and the moving platform includes two parts: the first platform and the second platform; the first platform and the second platform pass through bearings Rotationally connected; the lower end of the driven branch chain is connected to the first platform through a third hinge with two degrees of freedom in rotation; the lower end of the first active branch chain is connected to the first platform through a fourth hinge with three degrees of freedom in rotation A platform is rotationally connected; the lower end of the second active branch chain is hinged to a rotating shaft of the first cross shaft through a fifth hinge with a rotational degree of freedom, and the lower end of the third active branch chain is hinged through a fifth hinge with a rotational degree of freedom. The sixth hinge is hinged to one rotation shaft of the second cross shaft, and the other rotation shafts of the first cross shaft and the second cross shaft are respectively rotatably connected in the first swing shaft, and the first swing shaft is fixedly connected to the first hinge On the shaft, the first hinge shaft is rotatably connected to the first hinge seat, and the first hinge seat is fixedly connected to the first platform; the lower end of the fourth active branch chain passes through a The seventh hinge is hinged to a rotation shaft of the third cross shaft, the lower end of the fifth active branch chain is hinged to a rotation shaft of the fourth cross shaft through an eighth hinge with one degree of freedom of rotation, and the third cross shaft and the second cross shaft are hinged. The other rotating shafts of the four cross shafts are respectively rotatably connected in the second swing shaft, and the second swing shaft is fixedly connected to the second hinge shaft, and the second hinge shaft is rotatably connected to the second hinge seat, and the first The two hinge seats are fixedly connected on the first platform; one end of the first hinge shaft is connected with the first driving bevel gear, and the first driven bevel gear is engaged with the first driven bevel gear, and the first driven bevel gear is engaged with the first driven bevel gear. The bevel gear is fixed on the first rotating shaft, and the first rotating shaft is rotatably connected to the first platform, and the first driving pulley is fixedly connected to the first rotating shaft, and the first driving pulley is connected to the first driving pulley through a belt. A driven pulley is connected, the first driven pulley is fixed on the third rotating shaft, and the third rotating shaft is arranged on the second platform; one end of the second hinge shaft is connected with the second driving bevel gear, The second driving bevel gear is meshed with a second driven bevel gear, the second driven bevel gear is fixed on a second rotating shaft, and the second rotating shaft is rotatably connected to the first platform. The second driving pulley is fixedly connected to the second rotating shaft, and the second driving pulley is connected with the second driven pulley through a belt, and the second driven pulley is fixed on the fourth rotating shaft, and the fourth rotating shaft The lower end goes deep into the second platform through the third rotating shaft, and is fixedly connected with the third driving bevel gear, and the third driven bevel gear is meshed with the third driven bevel gear, and the third driven bevel gear is fixedly connected On the fifth rotating shaft, the fifth rotating shaft is rotatably connected to the second platform. the

The first driving bevel gear is arranged at the inner end of the first hinge shaft, and the second driving bevel gear is arranged at the inner end of the second hinge shaft. the

The advantages and positive effects of the present invention are: the mechanism can not only realize the positioning motion of one translation and two rotations of the moving platform, but also realize the attitude adjustment of the end effector around the A and/or C axis. The form of gear transmission is used to avoid the installation of servo motors in the positioning head, which effectively reduces the quality of the positioning head and improves the positioning accuracy and repeat positioning accuracy of the mechanism. The kinematic chain adopts the form of double active branch chain, which can make the overall rigidity of the mechanism high, and the dynamic performance is high, which has an advantageous feeding direction. the

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a structural representation of an active branched chain in the present invention;

Fig. 3 is the exterior view of the moving platform of the present invention;

Fig. 4 is a schematic diagram of the internal structure of the intermediate moving platform of the present invention. the

Detailed ways

In order to further understand the invention content, characteristics and effects of the present invention, the following examples are given hereby, and detailed descriptions are as follows in conjunction with the accompanying drawings:

Please refer to Figures 1 to 4, a parallel manipulator that can realize five-coordinate machining capabilities. The fixed frame 1 and the moving platform 8 are connected to the first, second, third, and third parts of the fixed frame 1 and the moving platform 8. Four, the fifth active branch chain 2,3,4,5,6, driven branch chain 7 forms. There is an opening in the center of the base of the fixed frame 1 , and the driven branch chain 7 is slidably connected with the fixed frame through a moving pair 9 . The first active branch chain 2 is the first kinematic chain, the second and third active branch chains 3 and 4 are the second kinematic chain, the fourth and fifth active branch chains 5 and 6 are the third kinematic chain, and the The first, second and third kinematic chains are spatially symmetrically distributed on the fixed frame 1 with respect to the driven branch chain. The first, second, third, fourth, and fifth active branch chains 2, 3, 4, 5, and 6 have the same structure, and each of the active branch chains includes a wall plate that is fixedly connected with the fixing frame 10. A servo motor 11 is installed on the upper end of the wall plate 10, the servo motor 11 drives the first ball screw 12, the first ball screw 12 is connected with a first nut, and the first nut is fixedly connected to In the connection block 14, the connection block 14 is slidably connected on the guide rail, and the guide rail is fixed on the wall plate 10, and the connection block connects with the driven rod 16 through the second hinge 15 with two rotational degrees of freedom. The upper ends are connected; the second hinge 15 has two rotational degrees of freedom, and can adopt structural forms such as a Hooke hinge. the

A moving platform 8 is arranged below the fixed frame 1, including a first platform 17 and a second platform 18, and the first platform 17 and the second platform 18 are rotatably connected by bearings. The lower end of the driven branch chain is connected to the first platform through a third hinge 19 with two rotational degrees of freedom, and the third hinge 19 may adopt a structure such as a Hooke hinge. The first active branch chain 2 is rotationally connected with the first platform through a fourth hinge 20, the fourth hinge has three rotational degrees of freedom, and can be in the form of a Hooke's hinge supplemented with a rotation axis, a ball hinge, or the like. The lower end of the second active branch chain 3 is hinged to a rotating shaft of the first cross shaft 23 through a fifth hinge 21 having a rotational degree of freedom, and the lower end of the third active branch chain 4 is hinged through a fifth hinge 21 having a rotational degree of freedom. The six hinges 22 are hinged to one rotating shaft of the second cross shaft 24, and the other rotating shafts of the first cross shaft 23 and the second cross shaft 24 are respectively rotatably connected in the first swing shaft 25, and the first swing shaft 25 is fixed Connected to the first hinge shaft 26 , the first hinge shaft 26 is rotatably connected to the first hinge base 27 , and the first hinge base 27 is fixedly connected to the first platform 17 . the

The connection between the fourth and fifth active branch chains and the first platform is the same as the connection between the third and fourth active branch chains and the first platform. The lower end of the fourth active branch chain 5 is hinged to a rotating shaft of the third cross shaft 30 through the seventh hinge 28 having a rotational degree of freedom, and the lower end of the fifth active branch chain 6 is hinged through the seventh hinge 28 having a rotational degree of freedom. Eight hinges 29 are hinged to one rotating shaft of the fourth cross shaft 31, and the other rotating shafts of the third cross shaft 30 and the fourth cross shaft 31 are respectively rotationally connected in the second swing shaft 32, and the second swing shaft 32 is fixed Connected to the second hinge shaft 33, the second hinge shaft 33 is rotatably connected to the second hinge base 34, and the second hinge base 34 is fixedly connected to the first platform 17; the first and second hinges One end of the shafts 26, 33 is respectively connected with the first and second driving bevel gears 37, 38 arranged in the first platform, the first driving bevel gear 37 is meshed with a first driven bevel gear 39, and the first driving bevel gear 37 is engaged with the first driven bevel gear 39, A driven bevel gear 39 is fixed on the first rotating shaft 35, and the first rotating shaft 35 is rotatably connected to the first platform 17, and the first driving pulley 41 is fixedly connected to the first rotating shaft 35. The first driving pulley 41 is connected with the first driven pulley 42 through a belt, and the first driven pulley 42 is fixed on the third rotating shaft 43, and the third rotating shaft 43 is arranged on the second platform 18; One end of the second hinge shaft 33 is connected with the second driving bevel gear 38, the second driving bevel gear 38 is meshed with a second driven bevel gear 40, and the second driven bevel gear 40 is fixed on the second rotating shaft 36, the second rotating shaft 36 is rotatably connected to the first platform 17, and the second rotating shaft 36 is fixedly connected with a second driving pulley 44, and the second driving pulley 44 is connected to the second driving pulley through a belt. The driven pulley 46 is connected, and the second driven pulley 46 is fixed on the fourth rotating shaft 45, and the lower end of the fourth rotating shaft 45 passes through the third rotating shaft and goes deep into the second platform, and is connected with the third driving bevel gear. 47, the third driven bevel gear 47 is meshed with a third driven bevel gear 49, the third driven bevel gear is fixed on the fifth rotating shaft 48, and the fifth rotating shaft is rotatably connected to the second on the platform. the

Below in conjunction with each figure, the present invention is further described:

As shown in Figures 1 and 2, a parallel manipulator capable of five-coordinate processing in the present invention consists of a fixed frame 1, a moving platform 8, and first, second, third, fourth, and fifth active branch chains. 2,3,4,5,6, driven branch chain 7 forms. Wherein, the first active branch chain 2 is the first kinematic chain, the second active branch chain 3 and the third active branch chain 4 form the second kinematic chain, the fourth active branch chain 5 and the fifth active branch chain 6 form the third movement chain chain. The driven branch chain 7 is located in the central opening of the fixed frame 1 , and the first, second and third kinematic chains are spatially symmetrically arranged on the fixed frame with respect to the driven branch chain 7 . The central opening is connected with the driven branch chain 7 through a moving pair 9 . the

As shown in Figure 3, each active branch chain includes a wall plate 10, a servo motor 11, a first lead screw nut structure, a second guide rail slider structure, a connecting block 14, a second hinge 15 and a driven rod 16 . The wall plate 10 is fixedly connected on the fixed frame, the servo motor 11 is installed on one end of the wall plate, the output shaft of the servo motor is connected with the first ball screw 12 through a coupling, and the second guide rail is arranged on the wall plate 13. The second slider and the first nut are fixedly installed on the connecting block 14, then the first ball screw 12 is threadedly connected with the first nut to form the first screw nut structure, and the second guide rail 13 is slidably connected with the second slider to form The structure of the second rail slider. The connecting block 14 is connected with the driven rod 16 through a second hinge 15, the second hinge 15 has two rotational degrees of freedom, and can adopt a structure such as a Hooke hinge. In this embodiment, the movement of the driven rod driven by the connecting block adopts the drive mode of servo motor-reducer-ball screw, but hydraulic, pneumatic and other structures can also be used as the drive mode. the

As shown in FIG. 4 , the moving platform 8 includes two parts, a first platform 17 and a second platform 18 , and the first platform 17 and the second platform 18 are rotatably connected through bearings. The lower end of the driven branch chain 7 is connected to the first platform 17 through a third hinge with two rotational degrees of freedom, and the third hinge may adopt a structure such as a Hooke hinge. The first active branch chain 2 is connected to the first platform 17 through a fourth hinge 20. The fourth hinge 20 has three rotational degrees of freedom, and can be in the form of a Hooke hinge supplemented by a rotation axis, a ball hinge, and the like. The lower end of the second active branch chain 3 is hinged to a rotating shaft of the first cross shaft 23 through a fifth hinge 21 having a rotational degree of freedom, and the lower end of the third active branch chain 4 is hinged through a fifth hinge 21 having a rotational degree of freedom. The six hinges 22 are hinged to one rotating shaft of the second cross shaft 24, and the other rotating shafts of the first cross shaft 23 and the second cross shaft 24 are respectively rotatably connected in the first swing shaft 25, and the first swing shaft 25 is fixed Connected to the first hinge shaft 26 , the first hinge shaft 26 is rotatably connected to the first hinge base 27 , and the first hinge base 27 is fixedly connected to the first platform 17 . the

As shown in FIG. 4 , the connection between the fourth and fifth active branch chains 5 , 6 and the first platform 17 is the same as the connection between the second and third active branch chains 3 , 4 and the first platform 17 . The lower end of the fourth active branch chain 5 is hinged to a rotating shaft of the third cross shaft 30 through the seventh hinge 28 having a rotational degree of freedom, and the lower end of the fifth active branch chain 6 is hinged through the seventh hinge 28 having a rotational degree of freedom. Eight hinges 29 are hinged with one rotation shaft of the fourth cross shaft 31, and the other rotation shafts of the third cross shaft 31 and the fourth cross shaft 31 are respectively rotatably connected in the second swing shaft 32, and the second swing shaft 32 is fixed Connected to the second hinge shaft 33 , the second hinge shaft 33 is rotatably connected to the second hinge base 34 , and the second hinge base 34 is fixedly connected to the first platform 17 . the

One end of the first hinge shaft 26 is connected with the first driving bevel gear 37 arranged in the first platform 17, and the inside of the first platform 17 is connected to the first rotating shaft 35 by bearing rotation along the axial direction of the driven branch chain, so The first rotating shaft 35 is connected with a first driven bevel gear 39 and a first driving pulley 41 through a key. The first driving pulley 41 is connected to the first driven pulley 42 through a belt, and the first driven pulley 42 is connected to a third rotating shaft 43 through a key, and the third rotating shaft 43 is arranged on the second platform 18 . Then the second kinematic chain, that is, when the servo motors of the second and third active branch chains 3 and 4 have different input values, the first pendulum shaft 25 rotates, driving the first hinge shaft 26 to rotate around its own axis, thereby driving the first hinge shaft 26 to rotate around its own axis. The rotation of the driving bevel gear 37 is transmitted to the first driven bevel gear 39 through gear engagement, and then transmitted to the first driving pulley 41 by the first rotating shaft 35, so that the first driven pulley 42 rotates under the action of the belt , to drive the third rotating shaft 43 and the second platform 18 to rotate around the C axis. In order to make the structure more compact, in this embodiment, the first driving bevel gear 37 is arranged at the inner end of the first hinge shaft 26 . the

One end of the second hinge shaft 33 is keyed to the second driving bevel gear 38 arranged in the first platform 17, and the second rotating shaft 36 is rotatably connected to the first platform 17 along the axial direction of the driven branch chain through a bearing. The second shaft 36 is keyed to the second driven bevel gear 40 and the second driving pulley 44 . The second driving pulley 44 is connected to the second driven pulley 46 through a belt, and the second driven pulley 46 is connected to the fourth rotating shaft 45 through a key. The lower end of the fourth rotating shaft 45 goes deep into the second platform through the third rotating shaft, and is fixedly connected with the third driving bevel gear 47. The third driven bevel gear 49 on the rotating shaft 48 is engaged with each other. Then the third kinematic chain, that is, when the fourth and fifth active branch chains 5 and 6 are driven with different input values, the second pendulum shaft 32 rotates, which drives the second hinge shaft 33 to rotate around its own axis, and then drives the second hinge shaft 33 to rotate around its own axis, thereby driving the first Two driving bevel gears 38 rotate, and the second driving bevel gear 38 meshes with the second driven bevel gear 40, so that the rotation is transmitted to the second rotating shaft 36, and the second rotating shaft 36 drives the second driving pulley 44 to rotate, and is transmitted to the second driving pulley 44 by the belt. The second driven pulley 46 drives the fourth rotating shaft 45 to rotate, and then transmits the rotation to the third driving bevel gear 47. The gear meshing action causes the third driven bevel gear 49 to rotate, and the fifth rotating shaft 48 can realize rotation around A shaft rotation. In order to make the structure more compact, in this embodiment, the second driving bevel gear 38 is arranged at the inner end of the second hinge shaft 33 . the

The novel parallel manipulator capable of five-coordinate processing of the present invention can realize five-degree-of-freedom motion. Since the connecting blocks 14 of the first, second and third kinematic chains can move relative to the fixed frame along the axis of the first ball screw, the connecting blocks connect with the driven rod through the second hinge 15 with two degrees of freedom of rotation. 16 connected, the connection between the first, second, and third kinematic chains and the moving platform has three degrees of freedom of rotation; The hinge is connected with the moving platform, so the moving platform can realize a translation and two rotations under the drive of each kinematic chain servo motor, that is, the mechanism can reach any position in a given working space to realize the positioning function. When the servo motors of the second active branch chain 3 and the third active branch chain 4 in the second kinematic chain have different input values, the rotation generated at the ends of the two branch chains can be transmitted to the second platform 18 through bevel gears and synchronous belts, Realize the rotation of the second platform 18 around the C axis. When the driving devices of the fourth active branch chain 5 and the fifth active branch chain 6 in the third kinematic chain have different input values, the rotation generated at the ends of the two branch chains can be transmitted to the fifth branch chain through bevel gears, synchronous belts, and bevel gears. The rotating shaft 48 realizes the rotation of the fifth rotating shaft around the A-axis, so the mechanism can realize five-degree-of-freedom motion. the

The novel parallel manipulator of the present invention, which can realize five-coordinate processing capability, can not only drive the mechanism to realize the positioning motion of one translation and two rotations at a faster speed, but also enable the dual active branch chain to have different inputs after reaching the designated position. , the drive mechanism produces rotation around the A and/or C axis to achieve attitude adjustment. Therefore, the mass of the positioning head can be effectively reduced, the overall rigidity of the mechanism is improved, the positioning accuracy and repeat positioning accuracy of the positioning head are increased, and the fast-forwarding ability and dynamic performance of the mechanism are improved. the

Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative and not restrictive. Those of ordinary skill in the art Under the enlightenment of the present invention, people can also make many forms without departing from the purpose of the present invention and the scope of protection of the claims, and these all belong to the protection scope of the present invention. the

Claims (2)

1. can realize the parallel manipulator of five coordinate working abilities, it is characterized in that, comprise fixed mount, the base central authorities of described fixed mount are connected with driven side chain by moving sets, around described driven side chain, be provided with uniform first, second and the 3rd kinematic chain, described first, second and the 3rd kinematic chain be fixed on described fixed mount, described the first kinematic chain comprises the first active branched chain, the second kinematic chain comprises second and the 3rd active branched chain, the 3rd kinematic chain comprises the 4th and the 5th active branched chain, described first, second, the 3rd, the 4th is identical with the structure of the 5th active branched chain,

Described in each, active branched chain includes the wallboard being fixedly connected with fixed mount, in described wallboard upper end, servomotor is installed, described driven by servomotor the first ball-screw, on described the first ball-screw, be connected with the first nut, described the first nut is fixed in contiguous block, described contiguous block is slidably connected on guide rail, and described guide rail is fixed on described wallboard, and described contiguous block is connected with follower lever upper end by second hinge with two rotational freedoms;

The below of described fixed mount is provided with a moving platform, and described moving platform comprises the first platform and two parts of the second platform; Described the first platform and described the second platform are rotatedly connected by bearing; The lower end of described driven side chain and described the first platform are by having the 3rd chain connection of double rotation freedom degrees; The lower end of described the first active branched chain is rotatedly connected by the 4th hinge and first platform with three-rotational-freedom;

The lower end of described the second active branched chain is by having the 5th hinge of a rotational freedom and a rotating shaft of the first cross axle is hinged, the lower end of described the 3rd active branched chain is by having the 6th hinge of a rotational freedom and a rotating shaft of the second cross axle is hinged, another rotating shaft of described the first cross axle and the second cross axle is rotatably connected on respectively in the first balance staff, described the first balance staff is fixed on the first hinge axis, described the first hinge axis is connected on the first hinge seat, the inner of described the first hinge axis is positioned at the first platform, described the first hinge seat is fixedly connected on described the first platform,

The lower end of described the 4th active branched chain is by having the 7th hinge of a rotational freedom and a rotating shaft of the 3rd cross axle is hinged, the lower end of described the 5th active branched chain is by having the 8th hinge of a rotational freedom and a rotating shaft of the 4th cross axle is hinged, another rotating shaft of described the 3rd cross axle and the 4th cross axle is rotatably connected on respectively in the second balance staff, described the second balance staff is fixed on the second hinge axis, described the second hinge axis is connected on the second hinge seat, the inner of described the second hinge axis is positioned at the second platform, described the second hinge seat is fixedly connected on the first platform, one end of described the first hinge axis is connected with the first drive bevel gear, in described the first drive bevel gear, be engaged with the first driven wheel of differential, described the first driven wheel of differential is fixed in the first rotating shaft, described the first rotating shaft is rotatably connected on described the first platform, in described the first rotating shaft, be connected with the first driving pulley, described the first driving pulley is connected with the first driven pulley by belt, and described the first driven pulley is fixed in the 3rd rotating shaft, and described the 3rd rotating shaft is arranged on the second platform,

One end of described the second hinge axis is connected with the second drive bevel gear, in described the second drive bevel gear, be engaged with the second driven wheel of differential, described the second driven wheel of differential is fixed in the second rotating shaft, described the second rotating shaft is rotatably connected on described the first platform, in described the second rotating shaft, be connected with the second driving pulley, described the second driving pulley is connected with the second driven pulley by belt, described the second driven pulley is fixed in the 4th rotating shaft, described the 4th rotating shaft lower end is deep in the second platform through the 3rd rotating shaft, and affixed with the 3rd drive bevel gear, in described the 3rd drive bevel gear, be engaged with the 3rd driven wheel of differential, described the 3rd driven wheel of differential is fixed in the 5th rotating shaft, described the 5th rotating shaft is rotatably connected on the second platform.

2. the parallel manipulator that realizes five coordinate working abilities according to claim 1, is characterized in that: described the first drive bevel gear is arranged on the inner of the first hinge axis, described the second drive bevel gear is arranged on the inner of the second hinge axis.

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